Purification method for calcium fluoride containing uranium

International Nuclear Information System (INIS)

Ogami, Takeshi

1998-01-01

Calcium fluoride (CaF 2 ) containing uranium is heated in an electrolytic bath having a cathode and an anode to form a molten salt, and the molten salt is electrolytically reduced to form metal uranium deposited on the surface of the cathode. The calcium fluoride molten salt separated by the deposition of generated metal uranium on the surface of the cathode is solidified by cooling. The solidified calcium fluoride is recovered. When metal uranium is deposited on the surface of the cathode by the electrolytic reduction of the molten salt, impurities such as plutonium and neptunium are also deposited on the surface of the anodes entrained by the metal uranium. Impurities having high vapor pressures such as americium and strontium are evaporated and removed from the molten salts. Then, nuclides such as uranium can thus be separated and recovered, and residual CaF 2 can be recovered in a state easily storable and reutilizable. (T.M.)

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

DEFF Research Database (Denmark)

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

2017-01-01

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

Studies on Pu(IV)/(III)-oxalate precipitation from nitric acid containing high concentration of calcium and fluoride ions

International Nuclear Information System (INIS)

Kalsi, P.K.; Pawar, S.M.; Ghadse, D.R.; Joshi, A.R.; Ramakrishna, V.V.; Vaidya, V.N.; Venugopal, V.

2003-01-01

Plutonium (IV)/(III) oxalate precipitation from nitric acid solution, containing large amount of calcium and fluoride ions was investigated. It was observed that direct precipitation of Pu (IV) oxalate from nitric acid containing large amount of calcium and fluoride ions did not give good decontamination of Pu from calcium and fluoride impurities. However, incorporation of hydroxide precipitation using ammonium hydroxide prior to Pu (IV) oxalate precipitation results into PuO 2 with much less calcium and fluoride impurities. Whereas, good decontamination from calcium and fluoride impurities could be obtained by employing Pu (III) oxalate precipitation directly from nitric acid containing large amount of calcium and fluoride ions. A method was also developed to recover Pu from the oxalate waste containing calcium and fluoride ions. (author)

Other Fluoride Products

Science.gov (United States)

... Private Wells Infant Formula Fluorosis Public Health Service Recommendation Water Operators & Engineers Water Fluoridation Additives Shortages of Fluoridation Additives Drinking Water Pipe Systems CDC-Sponsored Water Fluoridation Training Links to Other ...

Electrodeposition of some metals and niobium superconducting alloys from molten fluorides

International Nuclear Information System (INIS)

Cohen, U.

1978-01-01

The major goal of this thesis was to study the feasibility of electrodeposition from molten fluorides of the pure elements niobium, aluminium, tin, germanium and silicon, and the niboium superconducting intermetallic compounds with these elements, and to prepare and study films of these materials in the form of coherent and uniform coatings. Decomposition potential measurements with a gold anode were carried out on the alkali fluoride solvent and the fluoride salt solutions of niobium, aluminum, tin, and germanium to provide important initial thermodynamic data. Attempts to codeposit niobium and aluminum invariably failed, niobium being the exclusive deposit in all cases. Codeposition of niobium--tin alloys was demonstrated. Of the four intermetallic compounds of the niobium--germanium system, three were obtained as single-phase coatings. The superconducting compound (A15 phase) was not successfully electrodeposited in a single-phase form. It was obtained, however, in phase-mixture coatings. Application of alternating square wave pulses produced substantial changes in the morphology of niobium deposits. Silicon electrocrystallization epitaxy (ECE) was demonstrated for the first time. Uniform, coherent, and well adherent coatings of polycrystalline Si with a grain diameter of up to 40 to 50 μm were plated onto nonalloying metal substrates, such as silver and tungsten.These processes offer some attractive features for both integrated circuit technology and silicon solar cell fabrication. Aluminum, tin, and germanium were also electrodeposited from molten fluorides

Effect of xylitol, sodium fluoride and triclosan containing mouth rinse on Streptococcus mutans

Directory of Open Access Journals (Sweden)

Priya Subramaniam

2011-01-01

Full Text Available Introduction : Prevention of dental caries is one of the main strategies in contemporary pediatric dental practice. Mouth rinses are widely used as an adjunct to maintain oral hygiene. It is important for these products to be effective and safe for regular use in children. Objective : The aim of the study was to investigate the efficacy of a newly introduced xylitol, sodium fluoride and triclosan containing mouth rinse in reducing levels of plaque Streptococcus mutans and to compare it with that of a 0.12% chlorhexidine mouth rinse. Materials and Methods : Thirty children were randomly divided into two groups of 15 children each. Group I (study group was given a mouth rinse containing xylitol (5%, sodium fluoride (0.05% and triclosan (0.03% and Group II (control group was given a chlorhexidine (0.12% mouth rinse. Both mouth rinses were alcohol free. Mouth rinsing was carried out twice daily, half an hour after breakfast and half an hour following dinner, for a period of 21 days under the supervision of the investigator. Results: In both groups, there was a significant reduction in the mean S. mutans count at the end of 21 days (P < 0.001. No significant difference was observed between the two mouth rinses. Conclusion: The use of a low fluoride-xylitol based mouth rinse appears to be a suitable choice for regular use in children.

FLUORIDE TOXICITY – A HARSH REALITY

OpenAIRE

Bandlapalli Pavani; Mandava Ragini; David Banji; Otilia J F Banji; N Gouri Pratusha

2011-01-01

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

Grout formulation for disposal of low-level and hazardous waste streams containing fluoride

Science.gov (United States)

McDaniel, E.W.; Sams, T.L.; Tallent, O.K.

1987-06-02

A composition and related process for disposal of hazardous waste streams containing fluoride in cement-based materials is disclosed. the presence of fluoride in cement-based materials is disclosed. The presence of fluoride in waste materials acts as a set retarder and as a result, prevents cement-based grouts from setting. This problem is overcome by the present invention wherein calcium hydroxide is incorporated into the dry-solid portion of the grout mix. The calcium hydroxide renders the fluoride insoluble, allowing the grout to set up and immobilize all hazardous constituents of concern. 4 tabs.

Measuring the sustainability of tin in China.

Science.gov (United States)

Yang, Congren; Tan, Quanyin; Zeng, Xianlai; Zhang, Yuping; Wang, Zhishi; Li, Jinhui

2018-09-01

Tin is a component of many items used in daily activities, including solder in consumer electronics, tin can containing food and beverages, polyvinyl chloride stabilizers in construction products, catalysts in industrial processes, etc. China is the largest producer and consumer of refined tin, and more than 60% of this refined tin is applied in the electronics sector as solder. China is the leader in global economic growth; simultaneously, China is also a major producer and consumer of electrical and electronic equipment (EEE). Thus, future tin supply and demand in China are forecasted, based on the gross domestic product per capita and the average consumption of refined tin in past five years. Current tin reserves and identified resources in China can meet the future two decades of mine production, but import of tin will also be critical for China's future tin consumption. However, there will be a lot of uncertainty for import of tin from other countries. At the same time, virgin mining of geological ores is a process of high energy consumption and destruction of the natural environment. Hence recycling tin from Sn-bearing secondary resources like tailings and waste electrical and electronic equipment (WEEE) can not only address the shortage of tin mineral resources, but also save energy and protect the ecological environment. Copyright © 2018 Elsevier B.V. All rights reserved.

Beryllium production using beryllium fluoride

International Nuclear Information System (INIS)

Hubler, Carlos Henrique

1993-01-01

This work presents the beryllium production by thermal decomposition of the ammonium beryllium fluoride, followed by magnesium reduction, obtained in the small pilot plant of the Brazilian National Nuclear Energy Commission - Nuclear Engineering Institute

Reactivation of a tin oxide-containing catalyst

Science.gov (United States)

Upchurch, Billy T. (Inventor); Miller, Irvin M. (Inventor); Brown, Kenneth G. (Inventor); Hess, Robert V. (Inventor); Schryer, David R. (Inventor); Sidney, Barry D. (Inventor); Wood, George M. (Inventor); Paulin, Patricia A. (Inventor)

1989-01-01

A method for the reactivation of a tin oxide-containing catalyst of a CO.sub.2 laser is provided. First, the catalyst is pretreated by a standard procedure. When the catalyst experiences diminished activity during usage, the heated zone surrounding the catalyst is raised to a temperature which is the operating temperature of the laser and 400.degree. C. for approximately one hour. The catalyst is exposed to the same laser gas mixture during this period. The temperature of the heated zone is then lowered to the operating temperature of the CO.sub.2 laser.

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

NARCIS (Netherlands)

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

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

Tin-containing zeolites are highly active catalysts for the isomerization of glucose in water

OpenAIRE

Moliner, Manuel; Román-Leshkov, Yuriy; Davis, Mark E.

2010-01-01

The isomerization of glucose into fructose is a large-scale reaction for the production of high-fructose corn syrup (HFCS; reaction performed by enzyme catalysts) and recently is being considered as an intermediate step in the possible route of biomass to fuels and chemicals. Here, it is shown that a large-pore zeolite that contains tin (Sn-Beta) is able to isomerize glucose to fructose in aqueous media with high activity and selectivity. Specifically, a 10% (wt/wt) glucose solution containin...

Release path temperatures of shock-compressed tin from dynamic reflectance and radiance measurements

Energy Technology Data Exchange (ETDEWEB)

La Lone, B. M., E-mail: lalonebm@nv.doe.gov; Stevens, G. D.; Turley, W. D. [National Security Technologies, LLC, Special Technologies Laboratory, Santa Barbara, California 93111 (United States); Holtkamp, D. B. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Iverson, A. J. [National Security Technologies, LLC, Los Alamos Operations, Los Alamos, New Mexico 87544 (United States); Hixson, R. S.; Veeser, L. R. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); National Security Technologies, LLC, Los Alamos Operations, Los Alamos, New Mexico 87544 (United States)

2013-08-14

Dynamic reflectance and radiance measurements were conducted for tin samples shock compressed to 35 GPa and released to 15 GPa using high explosives. We determined the reflectance of the tin samples glued to lithium fluoride windows using an integrating sphere with an internal xenon flashlamp as an illumination source. The dynamic reflectance (R) was determined at near normal incidence in four spectral bands with coverage in visible and near-infrared spectra. Uncertainties in R/R{sub 0} are <2%, and uncertainties in absolute reflectance are <5%. In complementary experiments, thermal radiance from the tin/glue/lithium fluoride interface was recorded with similar shock stress and spectral coverage as the reflectance measurements. The two sets of experiments were combined to obtain the temperature history of the tin surface with an uncertainty of <2%. The stress at the interface was determined from photonic Doppler velocimetry and combined with the temperatures to obtain temperature-stress release paths for tin. We discuss the relationship between the experimental release paths and release isentropes that begin on the principal shock Hugoniot.

Shape-selective Valorization of Biomass-derived Glycolaldehyde using Tin-containing Zeolites

DEFF Research Database (Denmark)

Tolborg, Søren; Meier, Sebastian; Shunmugavel, Saravanamurugan

2016-01-01

sugars while hindering consecutive aldol reactions leading to hexose sugars. High yields of tetrose sugars (74 %) with minor amounts of vinyl glycolic acid (VGA), an α-hydroxyacid, are obtained using Sn-MFI with selectivities towards C4 products reaching 97 %. Tin catalysts having large pores or no pore...... structure (Sn-Beta, Sn-MCM-41, Sn-SBA-15, tin chloride) led to lower selectivities for C4 sugars due to formation of hexose sugars. In the case of Sn-Beta, VGA is the main product (30 %), illustrating differences in selectivity of the Sn sites in the different frameworks. Under optimized conditions, GA can...

High Fluoride Dentifrices for Elderly and Vulnerable Adults

DEFF Research Database (Denmark)

Ekstrand, Kim Rud

2016-01-01

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

Combinatorial Effects of Arginine and Fluoride on Oral Bacteria

OpenAIRE

Zheng, X.; Cheng, X.; Wang, L.; Qiu, W.; Wang, S.; Zhou, Y.; Li, M.; Li, Y.; Cheng, L.; Li, J.; Zhou, X.; Xu, X.

2015-01-01

Dental caries is closely associated with the microbial disequilibrium between acidogenic/aciduric pathogens and alkali-generating commensal residents within the dental plaque. Fluoride is a widely used anticaries agent, which promotes tooth hard-tissue remineralization and suppresses bacterial activities. Recent clinical trials have shown that oral hygiene products containing both fluoride and arginine possess a greater anticaries effect compared with those containing fluoride alone, indicati...

Structure-solubility relationships in fluoride-containing phosphate based bioactive glasses

Science.gov (United States)

Shaharyar, Yaqoot

The dissolution of fluoride-containing bioactive glasses critically affects their biomedical applications. Most commercial fluoride-releasing bioactive glasses have been designed in the soda-lime-silica system. However, their relatively slow chemical dissolution and the adverse effect of fluoride on their bioactivity are stimulating the study of novel biodegradable materials with higher bioactivity, such as biodegradable phosphate-based bioactive glasses, which can be a viable alternative for applications where a fast release of active ions is sought. In order to design new biomaterials with controlled degradability and high bioactivity, it is essential to understand the connection between chemical composition, molecular structure, and solubility in physiological fluids.Accordingly, in this work we have combined the strengths of various experimental techniques with Molecular Dynamics (MD) simulations, to elucidate the impact of fluoride ions on the structure and chemical dissolution of bioactive phosphate glasses in the system: 10Na2O - (45-x) CaO - 45P2O5 - xCaF2, where x varies between 0 -- 10 mol.%. NMR and MD data reveal that the medium-range atomic-scale structure of thse glasses is dominated by Q2 phosphate units followed by Q1 units, and the MD simulations further show that fluoride tends to associate with network modifier cations to form alkali/alkaline-earth rich ionic aggregates. On a macroscopic scale, we find that incorporating fluoride in phosphate glasses does not affect the rate of apatite formation on the glass surface in simulated body fluid (SBF). However, fluoride has a marked favorable impact on the glass dissolution in deionized water. Similarly, fluoride incorporation in the glasses results in significant weight gain due to adsorption of water (in the form of OH ions). These macroscopic trends are discussed on the basis of the F effect on the atomistic structure of the glasses, such as the F-induced phosphate network re-polymerization, in a

Use of fluoride systems for some fission product separation from residues of fast reactor spent fuel fluorination

International Nuclear Information System (INIS)

Shishkov, Yu.D.; Khomyakov, V.I.

1977-01-01

Investigated has been a possibility of the use of fluoride systems (acid nitrozyl fluoride and molten salts) for americium extraction from residues of fluorination of irradiated fuel containing mainly fluorides of rare earth compounds, alkali and alkaline earth elements. At treatment of fission product fluorides by acid nitrozyl fluoride only cesium and uranium fluorides dissolve, while americium and rare earth fluorides are practically non-soluble in it. The solubility of cesium, strontium, barium and fluorides of some other rare earth elements in molten cryolite at the temperature of 1000 deg C, Li-NaF and LiF-CaF 2 of eutectic content at 750 and 800 deg C are respectively 15-77 %. Cerium fluoride presents an exception, its solubility in cryolite being only 0.73%. At treatment of mixture of americium and lanthanum fluorides by molten salts in the weight ratio of 1:1, approximately 50% of lanthanum and 65-70% of americium turn into melt independent of the type of melt. The maximum melt output of americium is obtained at treatment of lanthanum and americium fluoride mixture by cryolite melt at the temperature of 1000 deg C. It is shown that the presence of rare earth of fluorides, except lanthanum fluoride, effect significantly of americium distribution over phases in the process of fluoride processing by the fluoride molten salts

Method of converting uranium fluoride to intermediate product for uranium oxide manufacture with recycling or reusing valuable materials

International Nuclear Information System (INIS)

Baran, V.; Moltasova, J.

1982-01-01

Uranium fluoride is acted upon by water with nitrate containing a cation capable of binding fluoride ions. The uranium is extracted, for instance, with tributyl phosphate with the generated organic phase containing the prevalent proportion of uranium and representing the required intermediate product and the aqueous phase from which is isolated the fluorine component which may be used within the fuel cycle. The nitrate component of the aqueous phase is recycled following treatment. It is also possible to act on uranium fluoride directly with an aqueous solution. Here the cations of nitrate form with the fluorides soluble nondissociated complexes and reduce the concentration of free fluoride ions. The nitrate +s mostly used in an amount corresponding to its solubility in the system prior to the introduction of UF 6 . The uranium from the solution with the reduced concentration of free fluoride ions is extracted into the reaction system under such conditions as to make the prevalent majority of fluorides and an amount of uranium smaller than 5x10 -2 mol/l remain in the aqueous phase and that such an amount of fluorides should remain in the organic phase which is smaller than corresponds to the fluorine/uranium molar ratio in the organic phase. Uranium contained in the organic phase is processed into uranium oxide, with advantage into UO 2 . From the isolated compounds of fluorine and the cation of the nitrate gaseous HF is released which is used either inside or outside of the fuel cycle. (J.P.)

Separative recovery with lime of phosphate and fluoride from an acidic effluent containing H3PO4, HF and/or H2SiF6.

Science.gov (United States)

Gouider, Mbarka; Feki, Mongi; Sayadi, Sami

2009-10-30

Fluoride content and flow-rate of fertilizer plant wastewater from phosphoric acid and/or triple superphosphate (TSP) production lead to the discharge of several thousand tons of fluoride (F(-)) per year and even more for phosphate (PO4(3-)). Since sustainability is an important environmental concern, the removal methods should allow phosphorus and fluoride to be recycled as a sustainable products for use as raw materials either in agricultural or industrial applications. In the present work, separative recovery with lime of these two target species was investigated. A preliminary speciation study, carried out on the crude effluent, showed that two forms of fluoride: HF and H2SiF6 are present in a highly acidic medium (pH approximately 2). Evidence that fluoride is present under both free (HF) and combined (H2SiF6) forms, in the phosphate-containing effluent, was provided by comparing potentiometric titration curves of a crude wastewater sample and synthetic acid mixtures containing H3PO4, HF and H2SiF6. In a second step synthetic effluent containing mixtures of the following acids: HF, H2SiF6 and H3PO4, were treated with lime. The behaviour of these compounds under lime treatment was analysed. The data showed that fluoride has a beneficial effect on phosphate removal. Moreover, by acting on the precipitation pH, a "selective" recovery of fluoride and phosphate ions was possible either from phosphoric acid/hydrofluoric acid or phosphoric acid/hexafluorosilicic acid mixtures. Indeed, the first stage of the separative recovery, led to a fluoride removal efficiency of 97-98% from phosphoric acid/hydrofluoric acid mixture. It was of 93-95% from phosphoric acid/hexafluorosilicic acid mixture. During the second stage, the phosphate precipitation reached 99.8% from both acidic mixtures whereas it did not exceed 82% from a solution containing H3PO4 alone. The XRD and IR analyses showed that during lime treatment, a H2SiF6 hydrolysis occurred, instead of CaSiF6 solid

77 FR 34938 - Certain Tin Mill Products From Japan: Continuation of Antidumping Duty Order

Science.gov (United States)

2012-06-12

... DEPARTMENT OF COMMERCE International Trade Administration [A-588-854] Certain Tin Mill Products... duty order on certain tin mill products from Japan would likely lead to continuation or recurrence of...: Background On August 28, 2000, the Department published the antidumping duty order on certain tin mill...

77 FR 5767 - Certain Tin Mill Products From Japan: Rescission of Antidumping Duty Administrative Review

Science.gov (United States)

2012-02-06

... DEPARTMENT OF COMMERCE International Trade Administration [A-588-854] Certain Tin Mill Products... duty order covering certain tin mill products from Japan. The period of review is August 1, 2010... parties to request an administrative review of the antidumping duty order on certain tin mill products...

76 FR 14902 - Certain Tin Mill Products From Japan: Rescission of Antidumping Duty Administrative Review

Science.gov (United States)

2011-03-18

... DEPARTMENT OF COMMERCE International Trade Administration [A-588-854] Certain Tin Mill Products... duty order covering certain tin mill products from Japan. The period of review is August 1, 2009... parties to request an administrative review of the antidumping duty order on certain tin mill products...

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

DEFF Research Database (Denmark)

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

2017-01-01

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

Fluorine uptake into human enamel around fluoride-containing dental materials during cariogenic pH cycling

Energy Technology Data Exchange (ETDEWEB)

Komatsu, H. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan)], E-mail: kom@den.hokudai.ac.jp; Yamamoto, H. [Graduate School of Dentistry, Osaka University, 1-8 Yamada-Oka, Suita 565-0871 (Japan); Nomachi, M. [Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043 (Japan); Yasuda, K. [The Wakasa wan Energy Research Center, 64-52-1 Hase, Tsuruga 914-0192 (Japan); Matsuda, Y.; Kinugawa, M.; Kijimura, T.; Sano, H. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Satou, T.; Oikawa, S.; Kamiya, T. [Advanced Radiation Technology, TARRI, JAEA, 1233 Watanuki-machi, Takasaki 370-1292 (Japan)

2009-06-15

Using PIGE (Proton Induced Gamma Emission) technique at TARRI (Takasaki Advanced Radiation Research Institute), Japan, we measured fluorine (F) uptake into the tooth enamel around two fluoride-containing materials during caries progression using pH cycling. Class V cavities in extracted human teeth were drilled and filled with fluoride-containing materials (i.e. 'Fuji IX' (FN) and 'UniFil flow with MEGA bond' (UF)) and a non-fluoride-containing material (i.e. 'SOLARE with MEGA bond' (SO)). Three 120 {mu}m longitudinal sections including the filling material were obtained from each tooth. In order to simulate daily acid attack occurring in the oral cavity, the pH cycling (pH 6.8-4.5) was carried out for 1, 3 and 5 weeks, separately. After pH cycling, the caries progression in all specimens was observed using transverse microradiography (TMR). The F and calcium distributions of the specimens were evaluated using PIGE and PIXE techniques. The F distribution of the specimens clearly showed the F uptake from FN into enamel adjacent to the filling material, while the F uptakes from UF and SO were not detected. For UF, the MEGA bond (non-fluoride-containing) between the tooth and UniFil flow interfered with the F absorption into the tooth. For FN, the amount of F uptake into the subsurface enamel increased during pH cycling. The amount of F uptake in 5-week pH cycling had significantly higher value compared to those in 1- and 3-week pH cycling. For UF and SO, there were no significant differences between the different durations of pH cycling. Among fluoride-containing materials, there were some differences in the F uptake with increased pH cycling, which could possibly lead to obtaining difference in clinical performance. The data obtained using PIGE and PIXE techniques were useful in understanding the benefit of fluorine by means of fluoride-containing material for preventing caries.

Fluorine uptake into human enamel around fluoride-containing dental materials during cariogenic pH cycling

International Nuclear Information System (INIS)

Komatsu, H.; Yamamoto, H.; Nomachi, M.; Yasuda, K.; Matsuda, Y.; Kinugawa, M.; Kijimura, T.; Sano, H.; Satou, T.; Oikawa, S.; Kamiya, T.

2009-01-01

Using PIGE (Proton Induced Gamma Emission) technique at TARRI (Takasaki Advanced Radiation Research Institute), Japan, we measured fluorine (F) uptake into the tooth enamel around two fluoride-containing materials during caries progression using pH cycling. Class V cavities in extracted human teeth were drilled and filled with fluoride-containing materials (i.e. 'Fuji IX' (FN) and 'UniFil flow with MEGA bond' (UF)) and a non-fluoride-containing material (i.e. 'SOLARE with MEGA bond' (SO)). Three 120 μm longitudinal sections including the filling material were obtained from each tooth. In order to simulate daily acid attack occurring in the oral cavity, the pH cycling (pH 6.8-4.5) was carried out for 1, 3 and 5 weeks, separately. After pH cycling, the caries progression in all specimens was observed using transverse microradiography (TMR). The F and calcium distributions of the specimens were evaluated using PIGE and PIXE techniques. The F distribution of the specimens clearly showed the F uptake from FN into enamel adjacent to the filling material, while the F uptakes from UF and SO were not detected. For UF, the MEGA bond (non-fluoride-containing) between the tooth and UniFil flow interfered with the F absorption into the tooth. For FN, the amount of F uptake into the subsurface enamel increased during pH cycling. The amount of F uptake in 5-week pH cycling had significantly higher value compared to those in 1- and 3-week pH cycling. For UF and SO, there were no significant differences between the different durations of pH cycling. Among fluoride-containing materials, there were some differences in the F uptake with increased pH cycling, which could possibly lead to obtaining difference in clinical performance. The data obtained using PIGE and PIXE techniques were useful in understanding the benefit of fluorine by means of fluoride-containing material for preventing caries.

Hydrolysis of bis(dimethylamido)tin to tin (II) oxyhydroxide and its selective transformation into tin (II) or tin (IV) oxide

KAUST Repository

Khanderi, Jayaprakash; Shi, Lei; Rothenberger, Alexander

2015-01-01

Sn6O4(OH)4, a hydrolysis product of Sn(NMe2)2, is transformed to tin (II) or tin (IV) oxide by solid and solution phase processing. Tin (II) oxide is formed by heating Sn6O4(OH)4 at ≤200 °C in air or under inert atmosphere. Tin (IV) oxide

International strategic minerals inventory summary report; tin

Science.gov (United States)

Sutphin, D.M.; Sabin, A.E.; Reed, B.L.

1990-01-01

The International Strategic Minerals Inventory tin inventory contains records for 56 major tin deposits and districts in 21 countries. These countries accounted for 98 percent of the 10 million metric tons of tin produced in the period 1934-87. Tin is a good alloying metal and is generally nontoxic, and its chief uses are as tinplate for tin cans and as solder in electronics. The 56 locations consist of 39 lode deposits and 17 placers and contain almost 7.5 million metric tons of tin in identified economic resources (R1E) and another 1.5 million metric tons of tin in other resource categories. Most of these resources are in major deposits that have been known for over a hundred years. Lode deposits account for 44 percent of the R1E and 87 percent of the resources in other categories. Placer deposits make up the remainder. Low-income and middle-income countries, including Bolivia and Brazil and countries along the Southeast Asian Tin Belt such as Malaysia, Thailand, and Indonesia account for 91 percent of the R1E resources of tin and for 61 percent of resources in other categories. The United States has less than 0.05 percent of the world's tin R1E in major deposits. Available data suggest that the Soviet Union may have about 4 percent of resources in this category. The industrial market economy countries of the United States, Japan, Federal Republic of Germany, and the United Kingdom are major consumers of tin, whereas the major tin-producing countries generally consume little tin. The Soviet Union and China are both major producers and consumers of tin. At the end of World War II, the four largest tin-producing countries (Bolivia, the Belgian Congo (Zaire), Nigeria, and Malaysia) produced over 80 percent of the world's tin. In 1986, the portion of production from the four largest producers (Malaysia, Brazil, Soviet Union, Indonesia) declined to about 55 percent, while the price of tin rose from about $1,500 to $18,000 per metric ton. In response to tin shortages

Radiodiagnostic complexes employing fluorine-containing tin reducing agents

International Nuclear Information System (INIS)

Hill, B.K.; Kubik, V.M.

1977-01-01

Radiodiagnostic agents for use in mammalian bodies comprising a radiocomplex which is the reaction product of Tc99m-pertechnetate ion, a diagnostic ligand and a tin (II) reducing agent selected from the group consisting of SnF 2 , MSnF 3 , MSn 2 F 5 and mixtures thereof, wherein M is NH 4 , Na, K, Li, Rb or Cs. Radiocomplex precursor compositions and methods of making the radiocomplex and radiodiagnostic agents are described

Fluorine uptake into the human enamel surface from fluoride-containing sealing materials during cariogenic pH cycling

Science.gov (United States)

Yasuhiro, Matsuda; Katsushi, Okuyama; Hiroko, Yamamoto; Hisanori, Komatsu; Masashi, Koka; Takahiro, Sato; Naoki, Hashimoto; Saiko, Oki; Chiharu, Kawamoto; Hidehiko, Sano

2015-04-01

To prevent the formation of caries and reduce dentin hypersensitivity, sealing materials, either with or without fluoride, are generally applied on the tooth in clinical practice. Application of fluoride-free sealing materials results in the formation of an acid-resistant layer on the tooth surface. On the other hand, fluoride-containing sealing materials might not only form an acid-resistant layer but could possibly further provide fluoride to enhance remineralization and reduce demineralization. In this study, the demineralization prevention ability and fluorine uptake rate in human enamel of fluoride-containing sealing materials ["MS coats F" (MSF)] and fluoride-free sealing materials ("hybrid coats 2" [HI]) were evaluated using an automatic pH cycling system. Each material was applied to the original tooth surface, the cut surfaces were covered with sticky wax, and the automatic pH-cycling system simulated daily acid changes (pH 6.8-4.5) occurring in the oral cavity for 4 weeks. Caries progression was analyzed using transverse microradiography (TMR) taken pre and post the 4 weeks of pH cycling. The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the proton-induced gamma emission (PIGE) and proton-induced X-ray (PIXE) techniques, respectively. TMR analysis showed that both MSF and HI had a caries-preventing effect after 4 weeks of pH cycling. PIGE/PIXE analysis demonstrated that only MSF resulted in fluoride uptake in the enamel surface. Therefore, MSF can help to form an acid-resistant layer and provide fluoride to the enamel surface. The presence of fluoride on the enamel surface suggested that MSF could prevent demineralization, even if the acid-resistant layer was removed, in clinical settings. The data obtained using the PIGE and PIXE techniques are useful for understanding the benefits of the use of a fluoride-containing sealing material for preventing caries.

Technical problems associated with the production of technetium Tc 99m tin(II) pyrophosphate kits

International Nuclear Information System (INIS)

Kowalsky, R.J.; Dalton, D.R.

1981-01-01

The amount of tin(II) required for adequate reduction, complexation, and stability of technetium Tc 99m pertechnetate in radiopharmaceutical kits, and methods of preventing the loss of tin(II) during formulation of these lyophilized kits are investigated. Tin(II) loss from stannous chloride solutions was studied under several conditions, including room air versus nitrogen atmospheres, during vial filling in a laminar-flow hood with samples frozen on dry ice versus samples at room temperature, during lyophilization, and during storage under refrigerated, ambient, and elevated temperatures. Various amounts of stannous chloride, ranging from 5 to 1000 microgram/ml, were used in formulating sodium pertechnetate Tc 99m kits containing 100 mCi technetium Tc 99m and 0.4 microgram total technetium. Samples were removed at various times; hydrolyzed technetium, pertechnetate, and technetium Tc 99m pyrophosphate were isolated on instant thin-layer chromatography-silica gel and quantified with a scintillation counter. The time necessary to deoxygenate distilled water by nitrogen purging was measured. Several sources of stannous chloride were assayed for tin(II) content. Tin(II) loss occurs rapidly in solution (15% in one hour) unless continuously protected with nitrogen, and during vial filling in a laminar-flow hood unless frozen with dry ice. No substantial loss of tin(II) was detected during lyophilization or during storage of lyophilized product at any of the three temperatures. A minimum of 400 microgram tin(II) was required to provide 90% technetium Tc 99m pyrophosphate at six hours after preparation. Adequate deoxygenation of small quantities (450 ml) of water was accomplished in less than one hour. Some stannous chloride salts were highly oxidized in the dry state, and only high-purity elemental tin wire gave acceptable yields of tin

method and container for production of diagnostic scanning agents

International Nuclear Information System (INIS)

Ruddock, C.F.

1979-01-01

The pertechnetate ion containing the technetium-99m isotope has limited applications in diagnostic scanning because it does not readily form complexes with materials which locate in specific parts of the body. Stannous salts have been widely used to reduce the pertechnetate to a form which readily complexes with materials. In the present invention, both a container and a more suitable metal reducing agent are discussed for transforming the technetium in pertechnetate for diagnostic scanning use. The vessel contains tin or a tin-containing alloy as a reducing agent for the pertechnetate and a complexant for the reduced technetium; all contents are sterile and dry. The present invention is advantageous over the stannous salts method since (1) problems of stannous salt instability during production, storage and after labelling are eliminated; (2) production procedures are simplified; (3) it is not essential to nitrogen purge vials before sterilisation; (4) it reduces toxicity; (5) the shelf life of diagnostic scanning kits may be dramatically improved; (6) the metal reducing agent may be sterilised by γ-irradiation without deteriorating; (7) the labelling technique can be performed over a wide pH range; and (8) the technique should be unaffected by technetium-99 in the technetium-99m. (U.K.)

Characterization of tin selenides synthesized by high-energy milling

Directory of Open Access Journals (Sweden)

Marcela Achimovičová

2011-12-01

Full Text Available Tin selenides SnSeX (x=1,2 were synthesized from tin and selenium powder precursors by high-energy milling in the planetary ballmill Pulverisette 6 (Fritsch, Germany. The orthorhombic tin selenide SnSe and the hexagonal tin diselenide SnSe2 phases were formed after4 min and 5 min of milling, respectively. Specific surface area of both selenides increased with increasing time of mechanochemicalsynthesis. The particle size distribution analysis demonstrated that the synthesized products contain agglomerated selenide particlesconsisting of numerous idiomorphic tin selenide crystals, measuring from 2 to more than 100 nm in diameter, which were also documentedby TEM. UV-Vis spectrophotometry confirmed that tin selenide particles do not behave as quantum dots.

Health impact of supplying safe drinking water containing fluoride below permissible level on flourosis patients in a fluoride-endemic rural area of West Bengal.

Science.gov (United States)

Majumdar, Kunal Kanti

2011-01-01

The problem of high fluoride concentration in groundwater resources has become one of the most important toxicological and geo-environmental issues in India. Excessive fluoride in drinking water causes dental and skeletal fluorosis, which is encountered in endemic proportions in several parts of the world. World Health Organization (WHO) guideline value and the permissible limit of fluoride as per Bureau of Indian Standard (BIS) is 1.5 mg/L. About 20 states of India, including 43 blocks of seven districts of West Bengal, were identified as endemic for fluorosis and about 66 million people in these regions are at risk of fluoride contamination. Studies showed that withdrawal of sources identified for fluoride often leads reduction of fluoride in the body fluids (re-testing urine and serum after a week or 10 days) and results in the disappearance of non-skeletal fluorosis within a short duration of 10-15 days. To determine the prevalence of signs and symptoms of suspected dental, skeletal, and non-skeletal fluorosis, along with food habits, addictions, and use of fluoride containing toothpaste among participants taking water with fluoride concentration above the permissible limit, and to assess the changes in clinical manifestations of the above participants after they started consuming safe drinking water. A longitudinal intervention study was conducted in three villages in Rampurhat Block I of Birbhum district of West Bengal to assess the occurrence of various dental, skeletal, and non-skeletal manifestations of fluorosis, along with food habits, addictions, and use of fluoride containing toothpaste among the study population and the impact of taking safe water from the supplied domestic and community filters on these clinical manifestations. The impact was studied by follow-up examination of the participants for 5 months to determine the changes in clinical manifestations of the above participants after they started consuming safe drinking water from supplied

The effect of a fluoride dentifrice containing an anticalculus agent on dental caries in children.

Science.gov (United States)

Lu, K H; Yen, D J; Zacherl, W A; Ruhlman, C D; Sturzenberger, O P; Lehnhoff, R W

1985-01-01

In this double-blind caries study, 1160 Taiwanese children (ages 8-15) completed a program using a test dentifrice containing 1.243 percent sodium fluoride and soluble pyrophosphates, or a control dentifrice without these agents. The average reduction of new carious tooth surfaces was 39 percent with the sodium fluoride dentifrice.

Fission products behavior in molten fluoride salts: Speciation of La{sup 3+} and Cs{sup +} in melts containing oxide ions

Energy Technology Data Exchange (ETDEWEB)

Rollet, Anne-Laure [CEMHTI, Conditions Extremes et Materiaux: Haute Temperature et Irradiation, CNRS, Universite d' Orleans, 1D avenue de la recherche scientifique, 45071 Orleans cedex 2 (France); PECSA, Physico-chimie des Electrolytes, Colloiedes et Sciences Analytiques, CNRS-UPMC-ESPCI, 4 place Jussieu, 75005 Paris (France); Veron, Emmanuel [CEMHTI, Conditions Extremes et Materiaux: Haute Temperature et Irradiation, CNRS, Universite d' Orleans, 1D avenue de la recherche scientifique, 45071 Orleans cedex 2 (France); Bessada, Catherine, E-mail: catherine.bessada@cnrs-orleans.fr [CEMHTI, Conditions Extremes et Materiaux: Haute Temperature et Irradiation, CNRS, Universite d' Orleans, 1D avenue de la recherche scientifique, 45071 Orleans cedex 2 (France)

2012-10-15

Graphical abstract: - Abstract: In this paper we address the effects of fission products on the speciation in molten fluoride salts. Numerous systems with cross-connections have been investigated in order to better identify the influence of CsF in a fluoride melt containing rare earth and oxides : LaF{sub 3}-AF (A = Li, Na, K, Rb and Cs), LaF{sub 3}-LiF-CsF, LaF{sub 3}-LiF-CaF{sub 2}, LaF{sub 3}-LiF-CaO, LaF{sub 3}-LiF-CaO-CsF. In this goal, we performed high temperature NMR experiments and followed in situ the evolution of {sup 19}F, {sup 23}Na, {sup 85}Rb, {sup 133}Cs and {sup 139}La NMR chemical shifts. In LaF{sub 3}-AF-CsF and LaF{sub 3}-AF-CaF{sub 2} systems, the coordination number of lanthanum cation ranges from 6 to 8 depending on the LaF{sub 3} concentration and on the polarizability of the other cations. The addition of oxide (CaO) in the latter mixtures leads to the formation of lanthanum oxyfluoride species that precipitate in LaOF when CaO concentration is increased. The addition of CsF to LaF{sub 3}-LiF-CaO yields to a displacement of the dissolved versus precipitated LaOF proportion.

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

Science.gov (United States)

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

2016-05-01

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

Annotated bibliography on the effects of water containing fluorides on container-grown crops

Energy Technology Data Exchange (ETDEWEB)

1962-01-01

Most of the literature on fluorine and plants relates to damage caused by atmospheric pollution, for example HF from aluminium works etc, which causes much greater damage than is possible with uptake through the roots. However a few papers do deal with uptake via the roots as follows: reviews of a general nature; uptake of fluorine and its effect on oxygen consumption; and fluoride induced chlorosis. The remainder deal with the effects of various concentrations of fluoride on container grown crops. One suggests that fluorine may be an essential trace element although its growth promoting action is not confirmed elsewhere. For the rest, the limits of fluorine tolerance are shown to be variable, related perhaps to the normal F content of the plant. No plant species however is recorded to have been damaged by concentrations of F below 10 ppM. The influence of nutrition on the appearance of symptoms of F toxicity, especially Ca nutrition but also N supply, is emphasized in two papers.

Fluorine uptake into the human enamel surface from fluoride-containing sealing materials during cariogenic pH cycling

Energy Technology Data Exchange (ETDEWEB)

Yasuhiro, Matsuda, E-mail: matsuda@den.hokudai.ac.jp [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan); Katsushi, Okuyama [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan); Hiroko, Yamamoto [Graduate School of Dentistry, Osaka University (Japan); Hisanori, Komatsu [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan); Masashi, Koka; Takahiro, Sato [Takasaki Advanced Radiation Research Institute, JAEA (Japan); Naoki, Hashimoto; Saiko, Oki; Chiharu, Kawamoto; Hidehiko, Sano [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan)

2015-04-01

To prevent the formation of caries and reduce dentin hypersensitivity, sealing materials, either with or without fluoride, are generally applied on the tooth in clinical practice. Application of fluoride-free sealing materials results in the formation of an acid-resistant layer on the tooth surface. On the other hand, fluoride-containing sealing materials might not only form an acid-resistant layer but could possibly further provide fluoride to enhance remineralization and reduce demineralization. In this study, the demineralization prevention ability and fluorine uptake rate in human enamel of fluoride-containing sealing materials [“MS coats F” (MSF)] and fluoride-free sealing materials (“hybrid coats 2” [HI]) were evaluated using an automatic pH cycling system. Each material was applied to the original tooth surface, the cut surfaces were covered with sticky wax, and the automatic pH-cycling system simulated daily acid changes (pH 6.8–4.5) occurring in the oral cavity for 4 weeks. Caries progression was analyzed using transverse microradiography (TMR) taken pre and post the 4 weeks of pH cycling. The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the proton-induced gamma emission (PIGE) and proton-induced X-ray (PIXE) techniques, respectively. TMR analysis showed that both MSF and HI had a caries-preventing effect after 4 weeks of pH cycling. PIGE/PIXE analysis demonstrated that only MSF resulted in fluoride uptake in the enamel surface. Therefore, MSF can help to form an acid-resistant layer and provide fluoride to the enamel surface. The presence of fluoride on the enamel surface suggested that MSF could prevent demineralization, even if the acid-resistant layer was removed, in clinical settings. The data obtained using the PIGE and PIXE techniques are useful for understanding the benefits of the use of a fluoride-containing sealing material for preventing caries.

Fluorine uptake into the human enamel surface from fluoride-containing sealing materials during cariogenic pH cycling

International Nuclear Information System (INIS)

Yasuhiro, Matsuda; Katsushi, Okuyama; Hiroko, Yamamoto; Hisanori, Komatsu; Masashi, Koka; Takahiro, Sato; Naoki, Hashimoto; Saiko, Oki; Chiharu, Kawamoto; Hidehiko, Sano

2015-01-01

To prevent the formation of caries and reduce dentin hypersensitivity, sealing materials, either with or without fluoride, are generally applied on the tooth in clinical practice. Application of fluoride-free sealing materials results in the formation of an acid-resistant layer on the tooth surface. On the other hand, fluoride-containing sealing materials might not only form an acid-resistant layer but could possibly further provide fluoride to enhance remineralization and reduce demineralization. In this study, the demineralization prevention ability and fluorine uptake rate in human enamel of fluoride-containing sealing materials [“MS coats F” (MSF)] and fluoride-free sealing materials (“hybrid coats 2” [HI]) were evaluated using an automatic pH cycling system. Each material was applied to the original tooth surface, the cut surfaces were covered with sticky wax, and the automatic pH-cycling system simulated daily acid changes (pH 6.8–4.5) occurring in the oral cavity for 4 weeks. Caries progression was analyzed using transverse microradiography (TMR) taken pre and post the 4 weeks of pH cycling. The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the proton-induced gamma emission (PIGE) and proton-induced X-ray (PIXE) techniques, respectively. TMR analysis showed that both MSF and HI had a caries-preventing effect after 4 weeks of pH cycling. PIGE/PIXE analysis demonstrated that only MSF resulted in fluoride uptake in the enamel surface. Therefore, MSF can help to form an acid-resistant layer and provide fluoride to the enamel surface. The presence of fluoride on the enamel surface suggested that MSF could prevent demineralization, even if the acid-resistant layer was removed, in clinical settings. The data obtained using the PIGE and PIXE techniques are useful for understanding the benefits of the use of a fluoride-containing sealing material for preventing caries

Production of sintered porous metal fluoride pellets

Science.gov (United States)

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)

Moessbauer study of the composition and corrosion behaviour of electrodeposited and cast brass containing 1-4 m% tin

International Nuclear Information System (INIS)

Vertes, A.; Suba, M.; Varsanyi-Lakatos, M.; Czako-Nagy, I.; Pchelnikov, A.P.; Losev, V.V.

1982-01-01

Moessbauer measurements on electrodeposited and cast brass containing 1-4 m% tin were carried out using conversion electron detector. It was found that the tin formed phases with copper but not with zinc. The identified phases were β, γ, epsilon and eta and their ratio depended on the tin concentration and on the preparation process of the brass. The corrosion behaviour of the samples was also studied. (author)

Design of an experiment for the production of a foamed tin sample

Science.gov (United States)

Wernimont, E.

1986-01-01

One of the major experiments in the GAS container is concerned with the experimental production of a foamed metal. A foamed metal is one that contains a significant amount of gas bubbles suspended in its solid volume. Purdue's GAS team proposes to do this with the help of a solid zinc carbonate that gives off carbon dioxide at high temperatures. Because of low energy requirements, the metal used for this experiment is tin. It is hoped that the use of near zero environment will keep the suspended bubbles more uniform than in an Earth based process, hence not depleting the physical strength of the material as greatly as is observed on Earth.

Comparative assessment of gastrointestinal irritant potency in man of tin(II) chloride and tin migrated from packaging.

Science.gov (United States)

Boogaard, Peter J; Boisset, Michel; Blunden, Steve; Davies, Scot; Ong, Teng Jin; Taverne, Jean-Pierre

2003-12-01

Tin is present in low concentrations in most canned foods and beverages, the highest levels being found in products packaged in unlacquered or partially lacquered tinplate cans. A limited number of case-reports of acute gastrointestinal disorders after consumption of food containing 100-500 mg/kg tin have been reported, but these reports suffer many insufficiencies. Controlled clinical studies on acute effects of tin migrated from packaging suggest a threshold concentration for adverse effects (AEs) of >730 mg/kg. Two separate randomised, single-centre, double-blind, crossover studies, enabling comparison of the tolerability of tin added as tin(II) chloride at concentrations of soup in 24 volunteers (Study 2) were carried out. Distribution studies were conducted to get insight in the acute AEs of low molecular weight (clear dose-response relationship was only observed when tin was added as tin(II) chloride in tomato juice. No clinically significant AEs were reported in Study 2 and comparison of the incidence of tin-related AEs showed no difference between the dose levels (including control). Tin species of low molecular weight in supernatant represented 31-32% of total tin in canned tomato soup versus 56-61% in juice freshly spiked with tin(II) chloride. Differences in the incidence of AEs following administration of tomato juice with 161 and 264 mg of tin per kg and tomato soup with 201 and 267 mg of tin per kg likely results from differences in the concentration of low molecular weight tin species and in the nature of tin complexes formed. The results of this work demonstrate that tin levels up to 267 mg/kg in canned food cause no AEs in healthy adults and support the currently proposed tin levels of 200 mg/kg and 250 mg/kg for canned beverages and canned foods, respectively, as safe levels for adults in the general population.

Penetration of fluoride-containing self-gelling liquids into human molar occlusal fissures in vitro.

Science.gov (United States)

Bottenberg, P; Slop, D; Coomans, D

1989-01-01

In this in vitro study the ability and speed of self-gelling liquid compositions to penetrate into fissures were evaluated. Two formulations containing either tetraethylsilicate, ammonium fluoride, and sodium lauryl sulfate or tetraethylsilicate, sodium fluoride, and cetylpyridinium chloride at different concentrations were used. It is shown that fissure penetration occurs when a certain minimum content of surface-active agent is present. Fissure penetration is achieved within 3-4 s, according to the fissure morphology.

Reduction in fluoride-induced genotoxicity in mouse bone marrow cells after substituting high fluoride-containing water with safe drinking water.

Science.gov (United States)

Podder, Santosh; Chattopadhyay, Ansuman; Bhattacharya, Shelley

2011-10-01

Treatment of mice with 15 mg l(-1) sodium fluoride (NaF) for 30 days increased the number of cell death, chromosomal aberrations (CAs) and 'cells with chromatid breaks' (aberrant cells) compared with control. The present study was intended to determine whether the fluoride (F)-induced genotoxicity could be reduced by substituting high F-containing water after 30 days with safe drinking water, containing 0.1 mg F ions l(-1). A significant fall in percentage of CAs and aberrant cells after withdrawal of F-treatment following 30 days of safe water treatment in mice was observed which was highest after 90 days, although their levels still remained significantly high compared with the control group. This observation suggests that F-induced genotoxicity could be reduced by substituting high F-containing water with safe drinking water. Further study is warranted with different doses and extended treatment of safe water to determine whether the induced damages could be completely reduced or not. Copyright © 2011 John Wiley & Sons, Ltd.

Magnesium fluoride recovery method

International Nuclear Information System (INIS)

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

1989-01-01

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

The Influence of Pseudomonas fluorescens on Corrosion Products of Archaeological Tin-Bronze Analogues

Science.gov (United States)

Ghiara, G.; Grande, C.; Ferrando, S.; Piccardo, P.

2018-01-01

In this study, tin-bronze analogues of archaeological objects were investigated in the presence of an aerobic Pseudomonas fluorescens strain in a solution, containing chlorides, sulfates, carbonates and nitrates according to a previous archaeological characterization. Classical fixation protocols were employed in order to verify the attachment capacity of such bacteria. In addition, classical metallurgical analytical techniques were used to detect the effect of bacteria on the formation of uncommon corrosion products in such an environment. Results indicate quite a good attachment capacity of the bacteria to the metallic surface and the formation of the uncommon corrosion products sulfates and sulfides is probably connected to the bacterial metabolism.

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

Directory of Open Access Journals (Sweden)

A Kowsari

2002-02-01

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

Removal of fluoride from water using aluminium containing compounds

Institute of Scientific and Technical Information of China (English)

M. Karthikeyan; K. P. Elango

2009-01-01

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

Fluoride removal from double four-membered ring (D4R) units in As-synthesized Ge-containing zeolites

KAUST Repository

Liu, Xiaolong; Ravon, Ugo; Tuel, Alain

2011-01-01

Fluoride anions can be removed from the framework of as-prepared Ge-containing zeolites ITQ-13 and ITQ-17 without modification of the crystallinity and crystal habit. By contrast to all-silica ITQ-13 for which fluoride could not get out from D4R

Telomere dysfunction and cell survival: roles for distinctTIN2-containing complexes

Energy Technology Data Exchange (ETDEWEB)

Kim, Sahn-Ho; Davalos, Albert R.; Heo, Seok-Jin; Rodier, Francis; Beausejour, Christian; Kaminker, Patrick; Campisi, Judith

2006-11-07

Telomeres are maintained by three DNA binding proteins, TRF1, TRF2 and POT1, and several associated factors. One factor, TIN2, binds TRF1 and TRF2 directly and POT1 indirectly. These and two other proteins form a soluble complex that may be the core telomere-maintenance complex. It is not clear whether subcomplexes exist or function in vivo. Here, we provide evidence for two TIN2 subcomplexes with distinct functions in human cells. TIN2 ablation by RNA interference caused telomere uncapping and p53-independent cell death in all cells tested. However, we isolated two TIN2 complexes from cell lysates, each selectively sensitive to a TIN2 mutant (TIN2-13, TIN2-15C). In cells with wild-type p53 function, TIN2-15C was more potent than TIN2-13 in causing telomere uncapping and eventual growth arrest. In cells lacking p53 function, TIN215C more than TIN2-13 caused genomic instability and cell death. Thus, TIN2 subcomplexes likely have distinct functions in telomere maintenance, and may provide selective targets for eliminating cells with mutant p53.

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

Science.gov (United States)

Santos, Lucineide de Melo; Reis, José Ivo Limeira dos; Medeiros, Maria Perolina de; Ramos, Sheyla Moreira; Araújo, Juliane Mendes de

2009-01-01

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

Well Waters Fluoride in Enugu, Nigeria

Directory of Open Access Journals (Sweden)

ISI Ogbu

2012-03-01

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

Telomere dysfunction and cell survival: Roles for distinct TIN2-containing complexes

Energy Technology Data Exchange (ETDEWEB)

Kim, Sahn-ho; Davalos, Albert R.; Heo, Seok-Jin; Rodier, Francis; Zou, Ying; Beausejour, Christian; Kaminker, Patrick; Yannone, Steven M.; Campisi, Judith

2007-10-02

Telomeres are maintained by three DNA binding proteins (TRF1, TRF2 and POT1), and several associated factors. One factor, TIN2, binds TRF1 and TRF2 directly and POT1 indirectly. Along with two other proteins, TPP1 and hRap1, these form a soluble complex that may be the core telomere maintenance complex. It is not clear whether sub-complexes also exist in vivo. We provide evidence for two TIN2 sub-complexes with distinct functions in human cells. We isolated these two TIN2 sub-complexes from nuclear lysates of unperturbed cells and cells expressing TIN2 mutants TIN2-13, TIN2-15C, which cannot bind TRF2 or TRF1, respectively. In cells with wild-type p53 function, TIN2-15C was more potent than TIN2-13 in causing telomere uncapping and eventual growth arrest. In cells lacking p53 function, TIN2-15C was more potent than TIN2-13 in causing telomere dysfunction and cell death. Our findings suggest that distinct TIN2 complexes exist, and that TIN2-15C-sensitive subcomplexes are particularly important for cell survival in the absence of functional p53.

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

Directory of Open Access Journals (Sweden)

Lucineide de Melo Santos

2009-09-01

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

Tin electrodeposition from sulfate solution containing a benzimidazolone derivative

Directory of Open Access Journals (Sweden)

Said BAKKALI

2016-11-01

Full Text Available Tin electrodeposition in an acidic medium in the presence of N,N’-1,3-bis-[N-3-(6-deoxy-3-O-methyl-D-glucopyranose-6-yl-2-oxobenzimidazol-1-yl]-2-tetradecyloxypropane as an additive was investigated in this work. The adequate current density and the appropriate additive concentration were determined by gravimetric measurements. Chronopotentiometric curves showed that the presence of the additive caused an increase in the overpotential of tin reduction. The investigations by cyclic voltammetry technique revealed that, in the presence and in absence of the additive, there were two peaks, one in the cathodic side attributed to the reduction of Sn2+ and the other one in the anodic side assigned to the oxidation of tin previously formed during the cathodic scan. The surface morphology of the tin deposits was studied by scanning electron microscopy (SEM and XRD.

Light emission from silicon with tin-containing nanocrystals

Directory of Open Access Journals (Sweden)

Søren Roesgaard

2015-07-01

Full Text Available Tin-containing nanocrystals, embedded in silicon, have been fabricated by growing an epitaxial layer of Si1−x−ySnxCy, where x = 1.6 % and y = 0.04 % on a silicon substrate, followed by annealing at various temperatures ranging from 650 ∘C to 900 ∘C. The nanocrystal density and average diameters are determined by scanning transmission-electron microscopy to ≈1017 cm−3 and ≈5 nm, respectively. Photoluminescence spectroscopy demonstrates that the light emission is very pronounced for samples annealed at 725 ∘C, and Rutherford back-scattering spectrometry shows that the nanocrystals are predominantly in the diamond-structured phase at this particular annealing temperature. The origin of the light emission is discussed.

Calculation of vapor pressure of fission product fluorides and oxyfluorides

International Nuclear Information System (INIS)

Roux, J.P.

1976-03-01

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

Electrochemical reduction of trinitrotoluene on core-shell tin-carbon electrodes

International Nuclear Information System (INIS)

Grigoriants, Irena; Markovsky, Boris; Persky, Rachel; Perelshtein, Ilana; Gedanken, Aharon; Aurbach, Doron; Filanovsky, Boris; Bourenko, Tatiana; Felner, Israel

2008-01-01

In this work, we studied the electrochemical process of 2,4,6-trinitrotoluene (TNT) reduction on a new type of electrodes based on a core-shell tin-carbon Sn(C) structure. The Sn(C) composite was prepared from the precursor tetramethyl-tin Sn(CH 3 ) 4 , and the product contained a core of submicron-sized tin particles uniformly enveloped with carbon shells. Cyclic voltammograms of Sn(C) electrodes in aqueous sodium chloride solutions containing TNT show three well-pronounced reduction waves in the potential range of -0.50 to -0.80 V (vs. an Ag/AgCl/Cl - reference electrode) that correspond to the multistep process of TNT reduction. Electrodes containing Sn(C) particles annealed at 800 deg. C under argon develop higher voltammetric currents of TNT reduction (comparing to the as-prepared tin-carbon material) due to stabilization of the carbon shell. It is suggested that the reduction of TNT on core-shell tin-carbon electrodes is an electrochemically irreversible process. A partial oxidation of the TNT reduction products occurred at around -0.20 V. The electrochemical response of TNT reduction shows that it is not controlled by the diffusion of the active species to/from the electrodes but rather by interfacial charge transfer and possible adsorption phenomena. The tin-carbon electrodes demonstrate significantly stable behavior for TNT reduction in NaCl solutions and provide sufficient reproducibility with no surface fouling through prolonged voltammetric cycling. It is presumed that tin nanoparticles, which constitute the core, are electrochemically inactive towards TNT reduction, but Sn or SnO 2 formed on the electrodes during TNT reduction may participate in this reaction as catalysts or carbon-modifying agents. The nitro-groups of TNT can be reduced irreversibly (via two possible paths) by three six-electron transfers, to 2,4,6-triaminotoluene, as follows from mass-spectrometric studies. The tin-carbon electrodes described herein may serve as amperometric sensors

Fluoride-sensitivity of growth and acid production of oral Actinomyces: comparison with oral Streptococcus.

Science.gov (United States)

Kawashima, Junko; Nakajo, Kazuko; Washio, Jumpei; Mayanagi, Gen; Shimauchi, Hidetoshi; Takahashi, Nobuhiro

2013-12-01

Actinomyces are predominant oral bacteria; however, their cariogenic potential in terms of acid production and fluoride sensitivity has not been elucidated in detail and compared with that of other caries-associated oral bacteria, such as Streptococcus. Therefore, this study aimed to elucidate and compare the acid production and growth of Actinomyces and Streptococcus in the presence of bicarbonate and fluoride to mimic conditions in the oral cavity. Acid production from glucose was measured by pH-stat at pH 5.5 and 7.0 under anaerobic conditions. Growth rate was assessed by optical density in anaerobic culture. Although Actinomyces produced acid at a lower rate than did Streptococcus, their acid production was more tolerant of fluoride (IDacid production 50 = 110-170 ppm at pH 7.0 and 10-13 ppm at pH 5.5) than that of Streptococcus (IDacid production 50 = 36-53 ppm at pH 7.0 and 6.3-6.5 ppm at pH 5.5). Bicarbonate increased acid production by Actinomyces with prominent succinate production and enhanced their fluoride tolerance (IDacid production 50 = 220-320 ppm at pH 7.0 and 33-52 ppm at pH 5.5). Bicarbonate had no effect on these variables in Streptococcus. In addition, although the growth rate of Actinomyces was lower than that of Streptococcus, Actinomyces growth was more tolerant of fluoride (IDgrowth 50 = 130-160 ppm) than was that of Streptococcus (IDgrowth 50 = 27-36 ppm). These results indicate that oral Actinomyces are more tolerant of fluoride than oral Streptococcus, and bicarbonate enhances the fluoride tolerance of oral Actinomyces. Because of the limited number of species tested here, further study is needed to generalize these findings to the genus level. © 2013 The Societies and Wiley Publishing Asia Pty Ltd.

76 FR 60001 - Certain Tin Mill Products From Japan; Final Results of the Second Expedited Sunset Review of the...

Science.gov (United States)

2011-09-28

... DEPARTMENT OF COMMERCE International Trade Administration [A-588-854] Certain Tin Mill Products... duty order on certain tin mill products from Japan, pursuant to section 751(c) of the Tariff [[Page... on certain tin mill products from Japan pursuant to section 751(c) of the Act. See Initiation of Five...

[The effects of topical fluoridation of enamel on the growth of cariogenic bacteria contained in the dental plaque].

Science.gov (United States)

Płuciennik-Stronias, Małgorzata; Zarzycka, Beata; Bołtacz-Rzepkowska, Elzbieta

2013-01-01

Dental caries is a bacterial disease. The most important element used in caries prevention is fluoride, which is derived from the air, diet or fluoride-containing preparations and materials, e.g. glass-ionomer restorations. Fluoride can inhibit metabolism and bacterial growth in the dental plaque. The aim of the study was to evaluate the effect of topical fluoridation of the enamel on the growth of Lactobacillus spp. in the dental plaque. The study was carried out in 15 patients with good oral hygiene, in whom three-day dental plaque from the enamel was examined. Next, fluoride was rubbed on the same surface and the examination of three-day dental plaque was repeated. No statistically significant differences (p = 0.475) in the amounts of Lactobacillus spp. in the plaque collected prior to and after the topical fluoridation were revealed. Fluoride rubbed in the enamel, did not affect the amount of Lactobacillus spp. in the dental plaque growing on this material.

Study on the treatment of photovoltaic wastewater using electrocoagulation: Fluoride removal with aluminium electrodes-Characteristics of products

Energy Technology Data Exchange (ETDEWEB)

Drouiche, N., E-mail: nadjibdrouiche@yahoo.fr [Silicon Technology Development Unit (UDTS), 2, Bd Frantz Fanon BP140, Alger-7-merveilles, 16200 (Algeria); Laboratory of Environmental Biotechnologies, Ecole Polytechnique d' Alger - 10, Avenue Pasteur El-Harrach (Algeria); Aoudj, S.; Hecini, M. [Silicon Technology Development Unit (UDTS), 2, Bd Frantz Fanon BP140, Alger-7-merveilles, 16200 (Algeria); Ghaffour, N. [Middle East Desalination Research Center, P.O. Box 21, P.C.133, Muscat (Oman); Lounici, H.; Mameri, N. [Laboratory of Environmental Biotechnologies, Ecole Polytechnique d' Alger - 10, Avenue Pasteur El-Harrach (Algeria)

2009-09-30

In this work, treatment of synthetic fluoride-containing solutions by electrocoagulation method using aluminium electrodes has been studied. Electrocoagulation was investigated for applied potential (10-30 V), electrolysis time and supporting electrolyte (NaCl) concentration (0-100 mg/L). The results showed that with increasing applied potential and electrolysis time, the Al{sup 3+} dosage increases, and thereby favouring the fluoride ions removal. It was also observed that defluoridation is dependant on the concentration of supporting electrolyte. Finally, X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy of X-rays and Fourier transform infrared spectroscopy were used to characterize the solid products formed by aluminium electrodes during the EC process.

Study on the treatment of photovoltaic wastewater using electrocoagulation: Fluoride removal with aluminium electrodes-Characteristics of products

International Nuclear Information System (INIS)

Drouiche, N.; Aoudj, S.; Hecini, M.; Ghaffour, N.; Lounici, H.; Mameri, N.

2009-01-01

In this work, treatment of synthetic fluoride-containing solutions by electrocoagulation method using aluminium electrodes has been studied. Electrocoagulation was investigated for applied potential (10-30 V), electrolysis time and supporting electrolyte (NaCl) concentration (0-100 mg/L). The results showed that with increasing applied potential and electrolysis time, the Al 3+ dosage increases, and thereby favouring the fluoride ions removal. It was also observed that defluoridation is dependant on the concentration of supporting electrolyte. Finally, X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy of X-rays and Fourier transform infrared spectroscopy were used to characterize the solid products formed by aluminium electrodes during the EC process.

Dual-energy CT with tin filter technology for the discrimination of renal lesion proxies containing blood, protein, and contrast-agent. An experimental phantom study

International Nuclear Information System (INIS)

Karlo, Christoph; Lauber, Arno; Goetti, Robert Paul; Baumueller, Stephan; Stolzmann, Paul; Scheffel, Hans; Desbiolles, Lotus; Marincek, Borut; Leschka, Sebastian; Schmidt, Bernhard; Alkadhi, Hatem

2011-01-01

To differentiate proxy renal cystic lesions containing protein, blood, iodine contrast or saline solutions using dual-energy CT (DECT) equipped with a new tin filter technology (TFT). 70 proxies (saline, protein, blood and contrast agent) were placed in unenhanced and contrast-enhanced kidney phantoms. DECT was performed at 80/140 kV with and without tin filtering. Two readers measured the CT attenuation values in all proxies twice. An 80/140 kV ratio was calculated. All intra- and interobserver agreements were excellent (r = 0.93-0.97; p 0.05). The CT attenuation of protein, blood and contrast agent solution differed significantly with tin filtering (p < 0.01-0.05). Significant differences were found between the ratios of protein and blood compared to contrast medium solution (each, p < 0.05) and between the ratios of protein and blood in both phantoms with tin filtering (each, p < 0.05). DECT allows discrimination between a proxy renal lesion containing contrast agent and lesions containing protein and blood through their different attenuation at 80 kV and 140 kV. Further discrimination between protein and blood containing proxies is possible when using a tin filter. (orig.)

Acute toxicity of ingested fluoride.

Science.gov (United States)

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.

Fluoride Concentration in Water, Cow Milk and Cow Urine from Smallholder Dairy Farms in Kiambu- Kenya

International Nuclear Information System (INIS)

Gikunju, J.K.; Maitho, T.E.; Kyule, M.N.; Mitema, E.S.; Mugera, G.M.

1999-01-01

Kiambu district is situated in central part of Kenya. most of the available land is suitable for agricultural use. majority of the farmers are small scale or subsistence farmers and they are involve in a variety of livestock activities e.g. dairy production, pig production and others in combination or as separate operations. excessive fluoride ingestion can cause specific dental and skeletal lesions and in severe cases adversely influence the health and productivity performance of domestic animals.therefore a study was designed to investigate the levels of flouride in urine, milk and water samples from small scale dairy farms in Kiambu. Water, cow urine and milk samples were collected in clean plastic containers from 84 small scale farms belonging to 6 dairy farmers co-operative societies (DFCs). The DFCs in this study were Kiambaa, Lari, Nderi, Kikuyu, Chania and Limuru. The fluoride concentration in water milk and urine were analysed using the potentiometric method of fluoride ion specific electrode. overall urine contained the highest fluoride concentration while milk contained the lowest fluoride levels. Fluoride levels in water, milk and urine were significantly different, (P>0.05). The mean fluoride concentration in water from all societies was 0.29 ppm while the mean fluoride concentration in milk 0.05 ppm. urine samples had the highest fluoride concentration, (1.5 ppm). The cooperative specific mean fluoride concentrations arranged in descending order were as follow: Nderi (2.8 ppm), Kikuyu (2.4 ppm), Kiambaa(1.9 ppm), Chania (1.6 ppm), Limuru (1.3 ppm) and Lari (1.0 ppm). The maximum fluoride concentration encountered in water in this study was 3.4 ppm, however adverse productivity has been reported in dairy animals consuming as low as 2.15 ppm in drinking water. The mean milk production in in kilograms per day per cow ranged from 2.5 to 6.9 when all six dairy co-operative societies were taken into consideration. this is far below the expected production

Recovery of plutonium from nitric acid containing oxalate and fluoride by a macroporous bifunctional phosphinic acid resin (MPBPA)

International Nuclear Information System (INIS)

Venugopal Chetty, K.; Godbole, A.G.; Swarup, R.; Vaidya, V.N.; Venugopal, V.; Vasudeva Rao, P.R.

2006-01-01

The sorption of Pu from nitric acid solutions containing oxalate/fluoride was studied using an indigenously available macroporous bifunctional phosphinic acid (MPBPA) resin. Batch experiments were carried out to obtain the distribution data of Pu(IV) with a view to optimize conditions for its recovery from nitric acid waste solutions containing oxalate or fluoride ions. The measurements showed high distribution ratio (D) values even in the presence of strong complexing ions, like oxalate and fluoride, indicating the possibility of recovery of Pu from these types of waste solution. Column studies were carried out using this resin to recover Pu from the oxalate supernatant waste solution, which showed that up to 99% of Pu could be adsorbed on the resin. Elution of Pu loaded on the resin was studied using different eluting agents. (author)

[The effects of topical fluoridation of Ketac Molar Aplicap glass-ionomer material on the growth of cariogenic bacteria contained in the dental plaque].

Science.gov (United States)

Płuciennik-Stronias, Małgorzata; Zarzycka, Beata; Bołtacz-Rzepkowska, Elzbieta

2013-01-01

Dental caries is a bacterial disease. The most important element used in caries prevention is fluoride, which is derived from the air, diet or fluoride-containing preparations and materials, e.g. glass-ionomer restorations. Modern fluoride-containing restorative materials are capable of releasing fluoride to the environment. Fluoride can be also accumulated in glass-ionomer cements, thus an attempt was made to saturate these materials with fluoride. The aim of the study was to evaluate the effect of topical fluoridation of Ketac Molar Aplicap glass-ionomer cement on the growth of Lactobacillus spp. in the dental plaque. The study was carried out in 15 patients with good oral hygiene, in whom 35 fillings with conventional glass-ionomer material, Ketac Molar Aplicap, were performed. After 6 months, three-day dental plaque from these fillings was examined. Next, fluoride was rubbed on the glass-ionomer surface and the examination of three-day dental plaque was repeated. No statistically significant differences (p = 0.143) in the amounts of Lactobacillus spp. in the plaque collected prior to and after topical fluoridation were revealed. Fluoride rubbed in the conventional glass-ionomer cement, Ketac Molar Aplicap, did not affect the amount of Lactobacillus spp. in the dental plaque growing on this material.

Molecular dynamics simulations of ejecta production from sinusoidal tin surfaces under supported and unsupported shocks

Science.gov (United States)

Wu, Bao; Wu, FengChao; Zhu, YinBo; Wang, Pei; He, AnMin; Wu, HengAn

2018-04-01

Micro-ejecta, an instability growth process, occurs at metal/vacuum or metal/gas interface when compressed shock wave releases from the free surface that contains surface defects. We present molecular dynamics (MD) simulations to investigate the ejecta production from tin surface shocked by supported and unsupported waves with pressures ranging from 8.5 to 60.8 GPa. It is found that the loading waveforms have little effect on spike velocity while remarkably affect the bubble velocity. The bubble velocity of unsupported shock loading remains nonzero constant value at late time as observed in experiments. Besides, the time evolution of ejected mass in the simulations is compared with the recently developed ejecta source model, indicating the suppressed ejection of unmelted or partial melted materials. Moreover, different reference positions are chosen to characterize the amount of ejecta under different loading waveforms. Compared with supported shock case, the ejected mass of unsupported shock case saturates at lower pressure. Through the analysis on unloading path, we find that the temperature of tin sample increases quickly from tensile stress state to zero pressure state, resulting in the melting of bulk tin under decaying shock. Thus, the unsupported wave loading exhibits a lower threshold pressure causing the solid-liquid phase transition on shock release than the supported shock loading.

Fluoride in diet

Science.gov (United States)

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

Advanced inorganic fluorides. Proceedings of the Second International Siberian workshop INTERSIBFLUORINE-2006

International Nuclear Information System (INIS)

Volkov, V.V.; Mit'kin, V.N.; Bujnovskij, A.S.; Sofronov, V.L.

2006-01-01

Proceedings of the Second International Siberian workshop ISIF-2006 on modern inorganic fluorides contain full author's texts of 82 plenary reports and posters on the main trends in chemistry and technology of inorganic fluorides and their various applications. The following new trends are reflected in the ISIF-2006 Proceedings versus the ISIF-2003 ones: production and use of of nano-sized systems and materials based on fluoride phases and fluorinating systems; chemistry of fluorofullerenes, fluorides of graphite and carbon materials; development of research and technical principles of economically viable process of depleted uranium hexafluoride conversion; vitrifying systems based on metal fluorides possessing valuable functional optical properties; mechanochemical processes and phenomena in chemistry of inorganic fluorides [ru

Catalytic Isomerization of Dihydroxyacetone to Lactic Acid and Alkyl Lactates over Hierarchical Zeolites Containing Tin

Directory of Open Access Journals (Sweden)

Agnieszka Feliczak-Guzik

2018-01-01

Full Text Available Hierarchical zeolites containing tin were obtained, characterized and used in a reaction of catalytic isomerization of dihydroxyacetone (DHA to lactic acid and alkyl lactates. These catalysts are characterized by preserved crystallinity and primary microporosity with the simultaneous existence of secondary porosity regarding mesopores, which facilitates access of large molecules of reagents to active centers. Creation of additional porosity was confirmed by X-ray diffraction and low-temperature nitrogen adsorption/desorption studies. The reaction of dihydroxyacetone isomerization was conducted in different reaction media such as methanol, ethanol or water with the use of two heating methods: microwave radiation and conventional heating. The application of microwave radiation enabled to reduce the reaction time to 1 h and achieve dihydroxyacetone conversion of >90% and high yields of the desired reaction products.

Reformulation of Business Strategies for Increasing Sales of TIN Product Stabilizer at PT Timah Industri

OpenAIRE

Sundoyo, Hadi; Hamsal, Mohammad

2013-01-01

PT. Timah Industri (PT TI) is a subsidiary of PT. Timah (Persero) Tbk which exploit comparative advantage of its parent company as the second largest tin producer in the world. With these advantages PT TI entered the downstream PVC stabilizer tin base. Starting from the difficulty of selling their products and then raised the question in inventory management. PT TI should immediately take strategic steps to save the tin chemical business continues to lose money from time to time. From the res...

Oral fluoride levels 1 h after use of a sodium fluoride rinse: effect of sodium lauryl sulfate.

Science.gov (United States)

Vogel, Gerald L; Schumacher, Gary E; Chow, Laurence C; Tenuta, Livia M A

2015-01-01

Increasing the concentration of free fluoride in oral fluids is an important goal in the use of topical fluoride agents. Although sodium lauryl sulfate (SLS) is a common dentifrice ingredient, the influence of this ion on plaque fluid and salivary fluid fluoride has not been examined. The purpose of this study was to investigate the effect of SLS on these parameters and to examine the effect of this ion on total (or whole) plaque fluoride, an important source of plaque fluid fluoride after a sufficient interval following fluoride administration, and on total salivary fluoride, a parameter often used as a surrogate measure of salivary fluid fluoride. Ten subjects accumulated plaque for 48 h before rinsing with a 12 mmol/l NaF (228 µg/g F) rinse containing or not containing 0.5% (w/w) SLS. SLS had no statistically significant effect on total plaque and total saliva fluoride but significantly increased salivary fluid and plaque fluid fluoride (by 147 and 205%, respectively). These results suggest that the nonfluoride components of topical agents can be manipulated to improve the fluoride release characteristics from oral fluoride reservoirs and that statistically significant change may be observed in plaque fluid and salivary fluid fluoride concentrations that may not be observed in total plaque and total saliva fluoride concentrations.

Tin-Containing Silicates: Identification of a Glycolytic Pathway via 3-Deoxyglucosone

DEFF Research Database (Denmark)

Tolborg, Søren; Meier, Sebastian; Sádaba, I.

2016-01-01

a cascade of four to five sequential steps. Currently, there is a limited understanding of the competing glycolytic pathways within these systems. Here we identify dehydration of glucose to 3-deoxyglucosone as an important pathway that occurs in addition to retro-aldol reaction of hexoses when using tin......-containing silicates. It is possible to influence the relative carbon flux through these pathways by controlling the amount of alkali metal salts present in the reaction mixture. In the absence of added potassium carbonate, at least 15–30% carbon flux via 3-deoxyglucosone is observed. Addition of just a few ppm...

Electrochemical dissolution of tin in methanesulphonic acid solutions

NARCIS (Netherlands)

de Greef, R.A.T.; Janssen, L.J.J.

2001-01-01

High-rate electroplating of tin on a moving steel strip is generally carried out in cells with dimensionally stable anodes. To obtain a matt tin deposit a concentrated acidic tin methanesulphonate solution containing a small concentration of sulphuric acid is used. The concentrated tin

In vitro enamel remineralization capacity of composite resins containing sodium trimetaphosphate and fluoride.

Science.gov (United States)

Tiveron, Adelisa Rodolfo Ferreira; Delbem, Alberto Carlos Botazzo; Gaban, Gabriel; Sassaki, Kikue Takebayashi; Pedrini, Denise

2015-11-01

This study evaluated the in vitro enamel remineralization capacity of experimental composite resins containing sodium trimetaphosphate (TMP) combined or not with fluoride (F). Bovine enamel slabs were selected upon analysis of initial surface hardness (SH1) and after induction of artificial carious lesions (SH2). Experimental resins were as follows: resin C (control—no sodium fluoride (NaF) or TMP), resin F (with 1.6% NaF), resin TMP (with 14.1% TMP), and resin TMP/F (with NaF and TMP). Resin samples were made and attached to enamel slabs (n = 12 slabs per material). Those specimens (resin/enamel slab) were subjected to pH cycling to promote remineralization, and then final surface hardness (SH3) was measured to calculate the percentage of surface hardness recovery (%SH). The integrated recovery of subsurface hardness (ΔKHN) and F concentration in enamel were also determined. Data was analyzed by ANOVA and Student-Newman-Keuls test (p Resins F and TMP/F showed similar SH3 values (p = 0.478) and %SH (p = 0.336) and differed significantly from the other resins (p resin TMP/F presented the lowest area of lesion (p resins (p = 0.042), but higher than in the other resins (p composite resin enhanced its capacity for remineralization of enamel in vitro. The combination of two agents with action on enamel favored remineralization, suggesting that composite resins containing sodium trimetaphosphate and fluoride could be indicated for clinical procedures in situations with higher cariogenic challenges.

Corrosion behavior of Ti and TI6Al4V in citrate buffers containing fluoride ions

Directory of Open Access Journals (Sweden)

Anelise Marlene Schmidt

2010-03-01

Full Text Available The effect of fluoride ions concentration on the electrochemical behavior of Ti grade 2 and Ti6Al4V in citrate buffers was studied. Open circuit potential (OCP measurements and voltammetric studies of the samples in the fluoride containing citrate buffers revealed a dissolution process when the pH falls below 5.0 and the NaF content is higher than 0.01 M. However, in citrate pH 7.6 the materials showed a passive behavior even in 0.1 M NaF. Some micrographs of Ti grade 2 obtained after longer immersion times in citrate pH 5.0 with 0.01 M NaF showed a surface attack. EIS (Electrochemical Impedance Sprectroscopy data obtained at the OCP revealed that the film resistance decreases when the immersion time is increased in pH 5.0 containing 0.1 M NaF. In the citrate pH 7.6 the EIS data indicated a two-layer model of an oxide film consisting of a more compact inner layer and a porous outer layer. On the other hand, the EIS results in citrate pH 4.0 change significantly when the fluoride ions concentration increases from 0.01 to 0.05 M. The electrochemical data revealed that the corrosion behavior of Ti grade 2 and Ti6Al4V in the citrate buffers depends on the pH, the fluoride content and the exposure time.

Daya antibakteri obat kumur chlorhexidine, povidone iodine, fluoride suplementasi zinc terhadap, Streptococcus mutans dan Porphyromonas gingivalis (Antibacterial effect of mouth washes containing chlorhexidine, povidone iodine, fluoride plus zinc on Strep

Directory of Open Access Journals (Sweden)

Betadion Rizki Sinaredi

2014-12-01

Full Text Available Background: Dental Caries and periodontal disease prevalence in Indonesian children are still high. Some efforts can be done to overcome the problem; one of them is the use of mouthwash to decrease pathogen microorganisms. The mouthwashes that commercially available in market are chlorhexidine, povidone Iodine and Fluoride with Zinc supplementation. Purpose: The purpose of this study was to examine the anti bacterial effect of the mouthwashes chlorhexidine, povidone iodine and fluoride with zinc supplementation against mix bacteria that found in the plaque, Streptococcus mutans and Porphyromonas gingivalis. Methods: The antibacterial effect was measured using disk diffusion test. The bacteria samples (plaque polybacteria, S.mutans and P. gingivalis were inoculated and spread in the petridish containing MHA. Paper discs containing the mouthwashes were placed in the petridish and incubated for 24 hours at 37oC (anaerobe for P. gingivalis, aerobe for S. mutans and polybacteria. The diameter of inhibition zone surrounding the paper discs were measured and compared between each active ingredient contained in mouthwash. Results: Chlorhexidine had the strongest antibacterial effect than povidone iodine and fluoride. Chlorhexidine was more effective to inhibited the growth of S. mutans than to polybacteria or P.Gingivalis, while Povidone iodine and fluoride were more effective to inhibited the growth of polybacteria. Conclusion: The mouthwash chlorhexidine was more effective to inhibit the growth of plaque polybacteria, Streptoccous mutans and Porphyromonas gingivalis compared with povidone iodine and fluoride with zinc supplementation.Latar belakang: Prevalensi karies gigi dan penyakit periodontal masih tinggi pada anak Indonesia. Usaha mengatasi hal tersebut antara lain melalui melalui penggunaan obat kumur untuk mengurangi jumlah kuman pathogen. Kandungan obat kumur yang beredar di pasar diantaranya adalah chlorhexidine, povidone iodine dan fluoride

Characterization of some tin-contained ancient glass beads found in China by means of SEM-EDS and raman spectroscopy.

Science.gov (United States)

Li, Qinghui; Liu, Song; Su, Bomin; Zhao, Hongxia; Fu, Qiang; Dong, Junqing

2013-02-01

A total of nine tin-contained ancient glass beads were characterized by a combination of scanning electron microscopy coupled with energy-dispersive X-ray spectrometry and Raman spectroscopy. These glass beads dated from 1st century BC to 10th century AD were excavated from the Xinjiang and Guangxi provinces of China. Two kinds of tin-based opacifiers/colorants included crystalline cassiterite (SnO(2)) and lead-tin yellow types II were first found in these soda lime glass beads. The tentative chronology of the tin-based opacifiers/colorants used in ancient glasses from China and the West was compared. In addition, several transition metal ions colorants were also found in these beads. The detailed study of the glassy matrices, crystalline inclusions, and the microstructural heterogeneities for these glass beads has revealed some valuable information to trace the possible making technology and provenances. Copyright © 2012 Wiley Periodicals, Inc.

Molecular dynamics simulations of ejecta production from sinusoidal tin surfaces under supported and unsupported shocks

Directory of Open Access Journals (Sweden)

Bao Wu

2018-04-01

Full Text Available Micro-ejecta, an instability growth process, occurs at metal/vacuum or metal/gas interface when compressed shock wave releases from the free surface that contains surface defects. We present molecular dynamics (MD simulations to investigate the ejecta production from tin surface shocked by supported and unsupported waves with pressures ranging from 8.5 to 60.8 GPa. It is found that the loading waveforms have little effect on spike velocity while remarkably affect the bubble velocity. The bubble velocity of unsupported shock loading remains nonzero constant value at late time as observed in experiments. Besides, the time evolution of ejected mass in the simulations is compared with the recently developed ejecta source model, indicating the suppressed ejection of unmelted or partial melted materials. Moreover, different reference positions are chosen to characterize the amount of ejecta under different loading waveforms. Compared with supported shock case, the ejected mass of unsupported shock case saturates at lower pressure. Through the analysis on unloading path, we find that the temperature of tin sample increases quickly from tensile stress state to zero pressure state, resulting in the melting of bulk tin under decaying shock. Thus, the unsupported wave loading exhibits a lower threshold pressure causing the solid-liquid phase transition on shock release than the supported shock loading.

Fluoride levels in tef [Eragrostis tef (Zucc.) Trotter] and enjera and its ...

African Journals Online (AJOL)

The main objective of this study was to estimate the fluoride levels in tef grain and in enjera, its fermentation product in different regions of Ethiopia, especially in the regions where tef is dominantly cultivated. The effect of water used to bake the enjera was assessed by preparing fluoride-containing water in the laboratory.

Laser-produced plasma EUV source using a colloidal microjet target containing tin dioxide nanoparticles

Science.gov (United States)

Higashiguchi, Takeshi; Dojyo, Naoto; Sasaki, Wataru; Kubodera, Shoichi

2006-10-01

We realized a low-debris laser-produced plasma extreme ultraviolet (EUV) source by use of a colloidal microjet target, which contained low-concentration (6 wt%) tin-dioxide nanoparticles. An Nd:YAG laser was used to produce a plasma at the intensity on the order of 10^11 W/cm^2. The use of low concentration nanoparticles in a microjet target with a diameter of 50 μm regulated the neutral debris emission from a target, which was monitored by a silicon witness plate placed 30 cm apart from the source in a vacuum chamber. No XPS signals of tin and/or oxygen atoms were observed on the plate after ten thousand laser exposures. The low concentration nature of the target was compensated and the conversion efficiency (CE) was improved by introducing double pulses of two Nd:YAG lasers operated at 532 and 1064 nm as a result of controlling the micro-plasma characteristics. The EUV CE reached its maximum of 1.2% at the delay time of approximately 100 ns with the main laser intensiy of 2 x10^11 W/cm^2. The CE value was comparable to that of a tin bulk target, which, however, produced a significant amount of neutral debris.

Effect of dog food containing 460 ppm fluoride on rat reproduction.

Science.gov (United States)

Marks, T A; Schellenberg, D; Metzler, C M; Oostveen, J; Morey, M J

1984-01-01

A one-generation, two-litter rat reproduction study was done in a kennel in Allegan County, Michigan, as part of an investigation of reproductive problems in Shetland sheepdogs (shelties). Since 1970, at least 115 sheltie litters at this kennel have been grossly deformed and/or have died, generally within 3 d of birth. The causative factor(s) appears to be associated with the environment, as the shelties have had successful pregnancies elsewhere. There was some concern that a potential threat to human reproduction also might exist in this area. After it was discovered that fluoride in the dog food had apparently caused mottled teeth and bony exostoses in dogs at this and at least two other kennels, dog-food fluoride content and local well water were investigated as possible causes of the reproductive problems. A two-way factorial statistical design allowed assessment of dietary fluoride content and water source and interaction between the two. UPj:TUC(SD)spf rats, 9 males and 18 females in each group, were assigned to treatment with high-fluoride dog food (460 ppm) and well water; high-fluoride dog food and distilled water; low-fluoride dog food (56 ppm) and well water; and low-fluoride dog food and distilled water. After 60 d in the kennel, the rats were mated. Even after two litters, the only adverse effect was dental fluorosis in the high-fluoride groups. The results indicated that rats cannot be used in the search for the cause(s) of reproductive problems in dogs in this kennel.

Kinetics study of Jatropha oil esterification with ethanol in the presence of tin (II) chloride catalyst for biodiesel production

Science.gov (United States)

Kusumaningtyas, Ratna Dewi; Ratrianti, Naomi; Purnamasari, Indah; Budiman, Arief

2017-01-01

Jatropha oil is one of the promising feedstocks for biodiesel production. Jatropha oil is non-edible oil hence utilization of this oil would not compete with the needs of food. However, crude jatropha oil usually has high free fatty acid (FFA) content. Due to this fact, direct alkaline-catalyzed transesterification of crude jatropha oil for biodiesel production cannot be performed. FFA in crude jatropha oil will react with a base catalyst, resulting in soap as by product and hindering methyl ester (biodiesel) production. Therefore, prior to a transesterification reaction, it is crucial to run a pretreatment step of jatropha oil which can lower the FFA content in the oil. In this work, the pretreatment process was conducted through the esterification reaction of FFA contained in crude jatropha oil with ethanol over tin (II) chloride catalyst to reduce the acid value of the feedstock. The feedstock was Indonesia crude jatropha oil containing 12.03% of FFA. The esterification reaction was carried out in a batch reactor with a molar ratio of FFA to ethanol was 1:60 and total reaction time was 180 minutes. Tin (II) chloride catalyst was varied at 2.5, 5, 7.5, and 10% wt, whereas the effect of the reaction temperature was studied at 35, 34, 55, and 65 °C. The best reaction conversion was 71.55%, achieved at the following condition: a reaction temperature of 65 °C, catalyst concentration of 10% wt, the reaction time of 180 min, and the molar ratio of FFA to ethanol was 1:60. Kinetics study was also conducted in this work. It was found that esterification reaction of jatropha oil FFA with ethanol catalyzed by tin(II) chloride fitted the first-order pseudo-homogeneous kinetics model. It was also revealed that the frequency factor (A) and the activation energy (Ea) were 4.3864 × 106 min-1 and 56.2513 kJ/mole, respectively.

Production and Release of ISOL Beams from Molten Fluoride Salt Targets

CERN Document Server

Mendonca, T M; Ghetta, V; Alibert, M; Heuer, D; Noah, E; Cimmino, S; Delonca, M; Gottberg, A; Kronberger, M; Ramos, J; Seiffert, C; Stora, T; CERN. Geneva. ATS Department

2014-01-01

In the framework of the Beta Beams study, a molten fluoride target has been proposed for the production of the required 1013 18Ne/s. The production and extraction of such rates are obtained on a circulating molten salt with proton beam energy beams at close to 1 MW power. As a most important step to validate the concept, a prototype has been designed and investigated at CERN-ISOLDE using a static target unit. The target material consisted of a binary fluoride system, NaF:LiF (39:61 % mol.), with melting point at 649ºC. The production of Ne beams has been monitored as a function of the target temperature and proton beam intensity. The prototype development and the results of the first online tests with 1.4 GeV proton beam are presented in this paper.

Decontamination of soils and materials containing medium-fired PuO{sub 2} using inhibited fluorides with polymer filtration technology

Energy Technology Data Exchange (ETDEWEB)

Temer, D.J.; Villarreal, R.; Smith, B.F. [Los Alamos National Lab., NM (United States)

1997-10-01

The decontamination of soils and/or materials from medium-fired plutonium oxide (PuO{sub 2}) with an effective and efficient decontamination agent that will not significantly dissolve the matrix requires a new and innovative technology. After testing several decontamination agents and solutions for dissolution of medium-fired PuO{sub 2}, the most successful decontamination solutions were fluoride compounds, which were effective in breaking the Pu-oxide bond but would not extensively dissolve soil constituents and other materials. The fluoride compounds, tetra fluoboric acid (HBF{sub 4}) and hydrofluorosilicic acid (H{sub 2}F{sub 6}Si), were effective in dissolving medium-fired PuO{sub 2}, and did not seem to have the potential to dissolve the matrix. In both compounds, the fluoride atom is attached to a boron or silicon atom that inhibits the reactivity of the fluoride towards other compounds or materials containing atoms less attracted to the fluoride atom in an acid solution. Because of this inhibition of the reactivity of the fluoride ion, these compounds are termed inhibited fluoride compounds or agents. Both inhibited fluorides studied effectively dissolved medium-fired PuO{sub 2} but exhibited a tendency to not attack stainless steel or soil. The basis for selecting inhibited fluorides was confirmed during leaching tests of medium-fired PuO{sub 2} spiked into soil taken from the Idaho National Engineering Laboratory (INEL). When dissolved in dilute HNO{sub 3}, HCl, or HBr, both inhibited fluoride compounds were effective at solubilizing the medium-fired PuO{sub 2} from spiked INEL soil.

Determination of total tin in canned food using inductively coupled plasma atomic emission spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Perring, Loic; Basic-Dvorzak, Marija [Department of Quality and Safety Assurance, Nestle Research Centre, P.O. Box 44, Vers chez-les-Blanc, 1000, Lausanne (Switzerland)

2002-09-01

Tin is considered to be a priority contaminant by the Codex Alimentarius Commission. Tin can enter foods either from natural sources, environmental pollution, packaging material or pesticides. Higher concentrations are found in processed food and canned foods. Dissolution of the tinplate depends on the of food matrix, acidity, presence of oxidising reagents (anthocyanin, nitrate, iron and copper) presence of air (oxygen) in the headspace, time and storage temperature. To reduce corrosion and dissolution of tin, nowadays cans are usually lacquered, which gives a marked reduction of tin migration into the food product. Due to the lack of modern validated published methods for food products, an ICP-AES (Inductively coupled plasma-atomic emission spectroscopy) method has been developed and evaluated. This technique is available in many laboratories in the food industry and is more sensitive than atomic absorption. Conditions of sample preparation and spectroscopic parameters for tin measurement by axial ICP-AES were investigated for their ruggedness. Two methods of preparation involving high-pressure ashing or microwave digestion in volumetric flasks were evaluated. They gave complete recovery of tin with similar accuracy and precision. Recoveries of tin from spiked products with two levels of tin were in the range 99{+-}5%. Robust relative repeatabilities and intermediate reproducibilities were <5% for different food matrices containing >30 mg/kg of tin. Internal standard correction (indium or strontium) did not improve the method performance. Three emission lines for tin were tested (189.927, 283.998 and 235.485 nm) but only 189.927 nm was found to be robust enough with respect to interferences, especially at low tin concentrations. The LOQ (limit of quantification) was around 0.8 mg/kg at 189.927 nm. A survey of tin content in a range of canned foods is given. (orig.)

Fluoride toothpaste containing 1.5% arginine and insoluble calcium as a new standard of care in caries prevention.

Science.gov (United States)

ten Cate, J M; Cummins, D

2013-01-01

In spite of obvious achievements in prevention, caries remains a prevalent disease. Fluorides are effective by inhibiting enamel and dentin demineralization and enhancing remineralization, but have little or no influence on bacterial processes in dental plaque. Dental caries is a continuum of stages from reversible, early lesions to irreversible, pre-cavitated lesions and, ultimately, to cavities. Prevention should focus on strengthening protective and reducing pathological factors, and careful monitoring of the disease state. While fluoride and the mineral aspects of caries have been in focus for decades, new insights into the etiology of caries have generated novel concepts and approaches to its prevention and treatment. The observation that some plaque bacteria can produce alkali metabolites and, thus, raise pH or neutralize acid formed in plaque has long been known. Such pH rise factors are related to caries susceptibility. Nourishing the plaque with substrates that encourage alkali-producing reactions is a protective factor in the caries continuum. This article reviews the results of clinical studies with a novel toothpaste containing 1.5% arginine, an insoluble calcium compound, and fluoride which have demonstrated superior remineralization of white spot enamel lesions and rehardening of root surface lesions, favorable effects on the de-/remineralization balance, as well as superior cavity prevention efficacy compared to toothpaste with fluoride alone. Studies have also confirmed formation of ammonia and elevated pH levels in subjects using the arginine-containing toothpaste. This novel toothpaste effectively combines the established effects of fluoride on de- and remineralization with reduction of caries-inducing pathological factors resulting from plaque metabolism.

The Fitness Cost of Fluoride Resistance for Different Streptococcus mutans Strains in Biofilms

Directory of Open Access Journals (Sweden)

Yanling Cai

2017-08-01

Full Text Available The cariogenic bacterium Streptococcus mutans can develop stable resistance to fluoride through chromosomal mutations in vitro. Fluoride-resistant S. mutans has seldom been isolated in clinical settings, despite the wide application of fluoride in oral-care products. One explanation is that the fluoride-resistant S. mutans strains have decreased fitness. However, so far, there has been no conclusive evidence to support this idea. The aim of this study was to investigate the fitness cost of 48-h biofilms of two fluoride-resistant S. mutans strains, UF35 and UA159-FR (UAFR, using the wild-type fluoride-sensitive strain UA159 as a reference. The engineered UF35 strain contains one point mutation, whereas UAFR, selected from NaF-containing agar plates, has multiple chromosomal mutations. All biofilms were formed for 48 h under a constantly neutral pH or a pH-cycling (8 h of neutral pH and 16 h of pH 5.5 condition in the absence of fluoride. The biomass of the biofilms was quantified with a crystal violet assay. The biofilms were also treated with chlorhexidine or solutions at pH 3.0, after which their lactic acid production was quantified. Compared to the UF35 and UA159 biofilms, the biomass of UAFR biofilms was two–four fold higher, and the UAFR biofilms were more resistant to chlorhexidine and low pH in terms of lactic acid production. No difference in biomass and lactic acid production was detected between UF35 and UA159 biofilms. The fluoride resistance of UAFR and UF35 strains in biofilms was further confirmed by treating the biofilms with NaF solutions. The level of NaF resistance of the three biofilms is generally ranked as follows: UAFR > UF35 > UA159. In conclusion, there is indeed a fitness consequence in UAFR, but surprisingly, this fluoride-resistant strain performs better than UF35 and UA159 under the described conditions. In addition, UF35 did not display a reduced fitness; it performed as well as the wild-type fluoride

Salivary Fluoride level in preschool children after toothbrushing with standard and low fluoride content dentifrice, using the transversal dentifrice application technique: pilot study

Directory of Open Access Journals (Sweden)

Fabiana Jandre Melo

2008-01-01

Full Text Available Objective: To investigate the salivary fluoride concentration in pre-school children after toothbrushing with dentifrice containing standard (1100ppmF/NaF and low (500ppmF/NaF fluoride concentration, using the transversal technique of placing the product on the toothbrush. Methods: Eight children of both sexes, ranging from 4 to 9 years, and 5 years and 6 months of age, participated in the study. The experiment was divided into two phases with a weekly interval. In the first stage, the children used the standard concentration dentifrice for one week, and in the second, the low concentration product. Samples were collected at the end of each experimental stage, at the following times: Before brushing, immediately afterwards, and after 15, 30 and 45 minutes. The fluoride contents were analyzed by the microdiffusion technique. Statistical analysis was done by the analysis of variance ANOVA and Student’s-t test (p<0.05. Results: The salivary fluoride concentration was significantly higher at all times, when the standard concentration product was used. The comparison between the Halogen concentration found before bushing and immediately afterwards, showed that there was a 6.8 times increase in the standard dentifrice (0.19 x 1.29μgF/ml and in the low concentration product, an increase of 20.5 times (0.02 x 0.41μgF/ml. Conclusion: Toothbrushing with both products promoted relevant increases in the salivary fluoride concentration; however, longitudinal studies are necessary to verify the clinical result of this measurement.

Combinatorial effects of arginine and fluoride on oral bacteria.

Science.gov (United States)

Zheng, X; Cheng, X; Wang, L; Qiu, W; Wang, S; Zhou, Y; Li, M; Li, Y; Cheng, L; Li, J; Zhou, X; Xu, X

2015-02-01

Dental caries is closely associated with the microbial disequilibrium between acidogenic/aciduric pathogens and alkali-generating commensal residents within the dental plaque. Fluoride is a widely used anticaries agent, which promotes tooth hard-tissue remineralization and suppresses bacterial activities. Recent clinical trials have shown that oral hygiene products containing both fluoride and arginine possess a greater anticaries effect compared with those containing fluoride alone, indicating synergy between fluoride and arginine in caries management. Here, we hypothesize that arginine may augment the ecological benefit of fluoride by enriching alkali-generating bacteria in the plaque biofilm and thus synergizes with fluoride in controlling dental caries. Specifically, we assessed the combinatory effects of NaF/arginine on planktonic and biofilm cultures of Streptococcus mutans, Streptococcus sanguinis, and Porphyromonas gingivalis with checkerboard microdilution assays. The optimal NaF/arginine combinations were selected, and their combinatory effects on microbial composition were further examined in single-, dual-, and 3-species biofilm using bacterial species-specific fluorescence in situ hybridization and quantitative polymerase chain reaction. We found that arginine synergized with fluoride in suppressing acidogenic S. mutans in both planktonic and biofilm cultures. In addition, the NaF/arginine combination synergistically reduced S. mutans but enriched S. sanguinis within the multispecies biofilms. More importantly, the optimal combination of NaF/arginine maintained a "streptococcal pressure" against the potential growth of oral anaerobe P. gingivalis within the alkalized biofilm. Taken together, we conclude that the combinatory application of fluoride and arginine has a potential synergistic effect in maintaining a healthy oral microbial equilibrium and thus represents a promising ecological approach to caries management. © International & American

Tin-containing zeolites are highly active catalysts for the isomerization of glucose in water.

Science.gov (United States)

Moliner, Manuel; Román-Leshkov, Yuriy; Davis, Mark E

2010-04-06

The isomerization of glucose into fructose is a large-scale reaction for the production of high-fructose corn syrup (HFCS; reaction performed by enzyme catalysts) and recently is being considered as an intermediate step in the possible route of biomass to fuels and chemicals. Here, it is shown that a large-pore zeolite that contains tin (Sn-Beta) is able to isomerize glucose to fructose in aqueous media with high activity and selectivity. Specifically, a 10% (wt/wt) glucose solution containing a catalytic amount of Sn-Beta (150 Sn:glucose molar ratio) gives product yields of approximately 46% (wt/wt) glucose, 31% (wt/wt) fructose, and 9% (wt/wt) mannose after 30 min and 12 min of reaction at 383 K and 413 K, respectively. This reactivity is achieved also when a 45 wt% glucose solution is used. The properties of the large-pore zeolite greatly influence the reaction behavior because the reaction does not proceed with a medium-pore zeolite, and the isomerization activity is considerably lower when the metal centers are incorporated in ordered mesoporous silica (MCM-41). The Sn-Beta catalyst can be used for multiple cycles, and the reaction stops when the solid is removed, clearly indicating that the catalysis is occurring heterogeneously. Most importantly, the Sn-Beta catalyst is able to perform the isomerization reaction in highly acidic, aqueous environments with equivalent activity and product distribution as in media without added acid. This enables Sn-Beta to couple isomerizations with other acid-catalyzed reactions, including hydrolysis/isomerization or isomerization/dehydration reaction sequences [starch to fructose and glucose to 5-hydroxymethylfurfural (HMF) demonstrated here].

Determination of fluoride content in UO2F2 and ADUF solution by ion selective electrode

International Nuclear Information System (INIS)

Samanta, Papu; Kumar, Pradeep; Bagchi, A.C.

2017-01-01

During production of uranium metal powder, liquid solution UO 2 F 2 and ADUF containing high content of fluoride gets generated. Fluoride being corrosive in nature, fluorides concentration needs to determined. Ion selective electrode, LaF 3 (Eu) crystal, has been used. Uranium was found to interfere with fluoride analysis. Study was carried out to selectively remove uranium by solvent extraction employing D2EHPA+Cyanex 923 and TBP in dodecane. The TBP was found effective to remove uranium. (author)

EFFECTIVITY OF TWO BLEACHING AGENT OF 10% CARBAMIDE PEROXIDE WITH AND WITHOUT POTASSIUM NITRATE-FLUORIDE (CLINICAL STUDY

Directory of Open Access Journals (Sweden)

Ayus Lusiyanti

2015-06-01

Full Text Available Tooth bleaching has become a popular treatment for esthetic improvement in dentistry. There are several 10% carbamide peroxide bleaching agents that are available in Indonesia which contained potassium nitrate-fluoride or without potassium nitrate-fluoride. However, there was no clinical report about these products in Indonesia. This study was conducted to compare the effectiveness of two bleaching and sensitivity of tooth and gingiva. Sixty-four participants were divided into 2 groups. The first group was treated with bleaching agent that contained potassium nitrate-fluoride (Opalescence PF, Ultradent. Bleaching treatment was done for 6-8 hours per night over a 2 week-period. Evaluations were performed at the baseline and at 3, 7, 14 day afterwards. Color change was measured using a value-ordered Vita classic shade guide; tooth and gingival sensitivity were examine using Electric Pulp Tester, Gingival Index and patient log. The results showed that there were no statistical differences in degree of color change between the two products. The mean color change after 2 weeks was 7-8 tabs lighter than baseline. Also there was no statistical difference in tooth and gingival sensitivity between the products. It can be concluded that 10% carbamide peroxide containing potassium nitrate-fluoride has the same effectiveness compared to other agent without potassium nitrate-fluoride for tooth color change and tooth and gingival sensitivity.

Tin-antimony oxide oxidation catalysts

Energy Technology Data Exchange (ETDEWEB)

Berry, Frank J. [Open University, Department of Chemistry (United Kingdom)

1998-12-15

Tin-antimony oxide catalysts for the selective oxidation of hydrocarbons have been made by precipitation techniques. The dehydration of the amorphous dried precipitate by calcination at increasingly higher temperatures induces the crystallisation of a rutile-related tin dioxide-type phase and the segregation of antimony oxides which volatilise at elevated temperatures. The rutile-related tin dioxide-type phase contains antimony(V) in the bulk and antimony(III) in the surface. Specific catalytic activity for the oxidative dehydrogenation of butene to butadiene is associated with materials with large concentrations of antimony(III) in the surface.

Method for identifying particulate fluoride compounds

Energy Technology Data Exchange (ETDEWEB)

Tufts, B J

1960-01-01

A method is described for identifying particulates containing fluorides and other complex fluorine compounds such as fluorosilicate in samples collected on membrane filters. The filter is treated with lead chloride to precipitate lead chlorofluoride at each fluoride-containing spot. This microspot is identified by examination in a light microscope. Sulfate and phosphate, which also precipitate if present, can be distinguished and do not interfere. Calibrations are given for the fluorides and the more insoluble salts, relating the original particle size to the reaction site size. Thus, the mass of the particles can be calculated. Results of some field tests in an area of fluoride pollution are given, and compared with standard testing procedures.

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

Science.gov (United States)

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

2017-08-01

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

Crevice corrosion of alloy 22 in fluoride and chloride containing solutions

International Nuclear Information System (INIS)

Carranza, Ricardo M.; Rodriguez, Martin A.

2005-01-01

Alloy 22 (N06022) is highly resistant to localized corrosion. Alloy 22 may be susceptible to crevice corrosion in pure chloride (Cl - ) solutions under aggressive environmental conditions. The effect of the fluoride (F - ) on the susceptibility to crevice corrosion induced by chloride ions is still not well established. The objective of the present work was to explore the crevice corrosion resistance of this alloy to different mixtures of fluorides and chlorides. Cyclic potentiodynamic polarization (CPP) tests were conducted in deaerated aqueous solutions of pure halide ions and also in different mixtures of chloride and fluoride at 90 C degrees and pH 6. The range of chloride concentration [Cl - ] was 0.001 M ≤ [Cl - ] ≤ 1 M and the range of molar fluoride to chloride ratio [F - ]/[Cl - ] was 0.1≤ [F - ]/[Cl - ] ≤ 10. Results showed that Alloy 22 was susceptible to crevice corrosion in all the pure chloride solutions but not in the pure fluoride solutions. A molar ratio [F - ]/[Cl - ] ranging from 5 to 10 was required for the inhibition of crevice corrosion to be complete in the halide mixtures. A moderate or nil inhibitive effect was observed for molar ratios [F - ]/[Cl - ] [es

Tin in canned food: a review and understanding of occurrence and effect.

Science.gov (United States)

Blunden, Steve; Wallace, Tony

2003-12-01

Tinplate is light gauge, steel sheet or strip, coated on both sides with commercially pure tin and has been used for well over a hundred years as a robust form of food packaging. Altogether, about 25,000 million food cans are produced and filled in Europe per annum, about 20% of these having plain internal (unlacquered) tin-coated steel bodies. Worldwide, the total for food packaging is approximately 80,000 million cans. Tinplate is also extensively used for the production of beverage cans. Europe produces and fills over 15,000 million tinplate beverage cans per annum all of which are internally lacquered. The use of tinplate for food and beverage packaging, will result in some tin dissolving into the food content, particularly when plain uncoated internal surfaces are used. The Provisional Tolerable Weekly Intake for tin is 14 mg/kg body weight and recommended maximum permissible levels of tin in food are typically 250 mg/kg (200 mg/kg UK) for solid foods and 150 mg/kg for beverages. However, the question arises as to whether evidence exists that such elevated levels of tin in food in any way constitute a risk to human health. This review considers the factors affecting the dissolution of tin, the reported measurements/surveys of actual levels of tin in canned foods and the studies and reports of acute (short term) toxicity relating to the ingestion of elevated levels of tin in food products. Chronic studies are mentioned, but are not covered in detail, since the review is mainly concerned with possible effects from the ingestion of single high doses. From published data, there appears to be a small amount of evidence suggesting that consumption of food or beverages containing tin at concentrations at or below 200 ppm has caused adverse gastrointestinal effects in an unknown but possibly small proportion of those exposed. However, the evidence supporting this assertion is derived from reports of adverse effects which offer data that are limited, incomplete or of

Fluoride removal from double four-membered ring (D4R) units in As-synthesized Ge-containing zeolites

KAUST Repository

Liu, Xiaolong

2011-11-22

Fluoride anions can be removed from the framework of as-prepared Ge-containing zeolites ITQ-13 and ITQ-17 without modification of the crystallinity and crystal habit. By contrast to all-silica ITQ-13 for which fluoride could not get out from D4R units, F is completely removed from Ge rich zeolites, even from D4R cages. This has been explained by the relaxing effect of germanium, making F less necessary for the stabilization of the small D4R units. Si/Ge ratios are similar in as-prepared and treated zeolites, indicating that the framework composition is not affected by the removal of anions. The fluoride-free zeolites possess XRD patterns similar to those of the as-made solids but their 29Si NMR spectra are significantly different, revealing the sensitivity of the method to the environment of silicon atoms in the framework. The extent of fluoride that can be removed from D4R units depends not only on the framework Ge content but also on the zeolite topology: for similar contents, F is much more easily eliminated from ITQ-17 than from ITQ-13. © 2011 American Chemical Society.

Effect of dentifrice containing fluoride and/or baking soda on enamel demineralization/remineralization: an in situ study.

Science.gov (United States)

Cury, J A; Hashizume, L N; Del Bel Cury, A A; Tabchoury, C P

2001-01-01

The additive effect of baking soda on the anticariogenic effect of fluoride dentifrice is not well established. To evaluate it, a crossover in situ study was done in three phases of 28 days. Volunteers, using acrylic palatal appliances containing four human enamel blocks, two sound (to evaluate demineralization) and two with artificial caries lesions (to evaluate remineralization), took part in this study. During each phase, 10% sucrose solution was dripped (3 times a day) only onto the sound blocks. After 10 min, a slurry of placebo, fluoride (F) or fluoride and baking soda (F+NaHCO(3)) dentifrice was dripped onto all enamel blocks. The results showed a higher F concentration in dental plaque formed during treatment with F+NaHCO(3) than placebo (pbaking soda neither improves nor impairs the effect of F dentifrice on reduction of demineralization and enhancement of remineralization of enamel.

Behavior of americium, curium, and certain fission products in fluoride melts in the presence of s olid extraction agents

International Nuclear Information System (INIS)

Alekseev, V.A.; Klokman, V.R.; Morozova, Z.E.; Ziv, V.S.

1986-01-01

The authors consider the behavior of americium, curium, and certain fission products (europium, cerium, yttrium, and strontium) in fluoride and chlode-fluoride melts in the presence of nonisomorphous solid phases: calcium fluoride and lanthanum and zirconium oxides. It is shown that the trace components enter the solid calcium fluoride in a regular fashion only in the presence of an adequate amount of oxygen in the melt. The effect of oxygen on the coprecipitation with calcium fluoride occurs because oxygen compounds of the elements must be formed in the melt, and these are then coprecipitated with the calcium fluoride

Fluoride export (FEX) proteins from fungi, plants and animals are 'single barreled' channels containing one functional and one vestigial ion pore

Science.gov (United States)

Berbasova, Tetyana; Nallur, Sunitha; Sells, Taylor; Smith, Kathryn D.; Gordon, Patricia B.; Tausta, Susan Lori

2017-01-01

The fluoride export protein (FEX) in yeast and other fungi provides tolerance to fluoride (F-), an environmentally ubiquitous anion. FEX efficiently eliminates intracellular fluoride that otherwise would accumulate at toxic concentrations. The FEX homolog in bacteria, Fluc, is a ‘double-barreled’ channel formed by dimerization of two identical or similar subunits. FEX in yeast and other eukaryotes is a monomer resulting from covalent fusion of the two subunits. As a result, both potential fluoride pores are created from different parts of the same protein. Here we identify FEX proteins from two multicellular eukaryotes, a plant Arabidopsis thaliana and an animal Amphimedon queenslandica, by demonstrating significant fluoride tolerance when these proteins are heterologously expressed in the yeast Saccharomyces cerevisiae. Residues important for eukaryotic FEX function were determined by phylogenetic sequence alignment and functional analysis using a yeast growth assay. Key residues of the fluoride channel are conserved in only one of the two potential fluoride-transporting pores. FEX activity is abolished upon mutation of residues in this conserved pore, suggesting that only one of the pores is functional. The same topology is conserved for the newly identified FEX proteins from plant and animal. These data suggest that FEX family of fluoride channels in eukaryotes are ‘single-barreled’ transporters containing one functional pore and a second non-functional vestigial remnant of a homologous gene fusion event. PMID:28472134

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

Energy Technology Data Exchange (ETDEWEB)

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

2012-08-01

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

Hydrolysis of bis(dimethylamido)tin to tin (II) oxyhydroxide and its selective transformation into tin (II) or tin (IV) oxide

KAUST Repository

Khanderi, Jayaprakash

2015-03-01

Sn6O4(OH)4, a hydrolysis product of Sn(NMe2)2, is transformed to tin (II) or tin (IV) oxide by solid and solution phase processing. Tin (II) oxide is formed by heating Sn6O4(OH)4 at ≤200 °C in air or under inert atmosphere. Tin (IV) oxide nanoparticles are formed in the presence of a carboxylic acid and base in air at room temperature. IR spectroscopy, Raman spectroscopy, thermogravimetry (coupled with infrared spectroscopy), powder X-ray diffraction, high temperature X-ray diffraction, scanning electron and transmission electron microscopy are used for the characterization of Sn6O4(OH)4 and the investigation of its selective decomposition into SnO or SnO2. Spectroscopic and X-ray diffraction results indicate that SnO is formed by the removal of water from crystalline Sn6O4(OH)4. SEM shows octahedral morphology of the Sn6O4(OH)4, SnO and SnO2 with particle size from 400 nm-2 μm during solid state conversion. Solution phase transformation of Sn6O4(OH)4 to SnO2 occurs in the presence of potassium glutarate and oxygen. SnO2 particles are 15-20 nm in size.

Biodegradation of Tributyltin (TBT) by Extremophile Bacteria from Atacama Desert and Speciation of Tin By-products.

Science.gov (United States)

Yáñez, Jorge; Riffo, Paula; Santander, Paola; Mansilla, Héctor D; Mondaca, María Angélica; Campos, Víctor; Amarasiriwardena, Dulasiri

2015-07-01

Biodegradation of tributyltin (TBT) by four tin resistant Gram negative bacteria isolated from extremely contaminated river sediments in the Atacama Desert in Chile was studied. Moraxella osloensis showed the greatest resistance and degradation capability of TBT, producing less toxic by-products, such as dibutyltin (DBT) and inorganic tin. In 7 days, approximately 80 % of TBT degradation was achieved, generating close to 20 % of DBT as degradation product. The degradation rate constant (k) was 0.022 [day(-1)] and TBT half-life (t1/2) in culture was 4.3 days. Debutylation is stated a probable mechanism of TBT degradation.

High temperature EXAFS experiments in molten actinide fluorides: The challenge of a triple containment cell for radioactive and aggressive liquids

Science.gov (United States)

Bessada, Catherine; Zanghi, Didier; Pauvert, Olivier; Maksoud, Louis; Gil-Martin, Ana; Sarou-Kanian, Vincent; Melin, Philippe; Brassamin, Séverine; Nezu, Atsushi; Matsuura, Haruaki

2017-10-01

An airtight double barrier cell with simple geometry has been developed for X-rays absorption measurements at high temperature in solid and molten actinide fluorides. The aim was both to improve the air tightness, to avoid any possible leakage and to maintain the high quality of the signal. The dimensions of the heating chamber were also constrained and minimized to be compatible with the limited space available usually on synchrotron beam lines and with a geometry suitable for absorption/diffraction measurements at high temperature. The design of the double barrier cell was also driven by the safety requirements in every experiment involving radioactive materials. The furnace itself was designed to ensure easy operating modes and disassembly, the aim being to consider the furnace as the ultimate containment. The cell has been tested with different molten fluorides up to more than 1000 °C, starting from non-radioactive LiF-ZrF4 mixtures in order to prove that the cell is absolutely airtight and that not any contamination of the environment occurs. Then it has been successfully applied to thorium fluoride- and uranium fluoride-alkali fluorides mixtures.

Fluoride varnish reduces white spot lesions during orthodontic treatment.

Science.gov (United States)

Shafi, Imran

2008-01-01

This was a randomised controlled trial (RCT) set in a community dental practice. The test varnish was a commercially available product, Fluor Protector (Ivoclar Vivadent, Schaan, Liechtenstein), containing 0.1% fluoride as difluorosilane in a polyurethane varnish base. The placebo varnish applied had an identical composition but without fluoride. The incidence and prevalence of white spot lesions (WSL) on the upper incisors, cuspids and premolars were recorded, as scored from digital photographs by two independent examiners. In the case of disagreement, cases were re-examined until a consensus was achieved. The incidence of WSL during the treatment period was 7.4% in the fluoride varnish group compared with 25.3% placebo group (P <0.001). The mean progression score was significantly lower in the fluoride varnish group than in the placebo group, (0.8 +/- 2.0 vs 2.6 +/- 2.8; P <0.001). The absolute risk reduction was 18% and the number-needed-to-treat was calculated to be 5.5 (95% confidence interval, 3.7-10.9). The results strongly suggest that regular topical fluoride varnish applications may reduce the development of WSL adjacent to the bracket base during treatment with fixed appliances.

Preliminary study of tin slag concrete mixture

Science.gov (United States)

Hashim, Mohd Jamil; Mansor, Ishak; Pauzi Ismail, Mohamad; Sani, Suhairy; Azmi, Azhar; Sayuti, Shaharudin; Zaidi Ibrahim, Mohd; Adli Anuar, Abul; Rahim, Abdul Adha Abdul

2018-01-01

The study focuses on practices to facilitate tin smelting industry to reduce radioactive waste product (Tin Slag) by diluting its radioactivity to a safe level and turning it to a safer infrastructural building product. In the process the concrete mix which include Portland cement, sand, tin slag, water and plasticizer are used to produce interlocking brick pavements, piles and other infrastructural products. The mixing method follows DOE (UK) standard method of mixing targeted at in selected compressive strength suitable for its function and durability. A batching machine is used in the mixing and six test cubes are produced for the test. The testing equipment used are a compressional machine, ultrasonic measurement and a Geiger Muller counter to evaluate of the concrete mix to find the lowest emission of radiation surface dose without compromising the strength of concrete mix. The result obtained indicated the radioactivity of tin slag in the mixing process has reduced to background level that is 0.5μSv/h while the strength and workability of the concrete has not been severely affected. In conclusion, the concrete mix with tin slag has shown the potential it can be turned into a safe beneficial infrastructural product with good strength.

Fluorine uptake into human enamel around a fluoride-containing dental material during cariogenic pH cycling

International Nuclear Information System (INIS)

Komatsu, H.; Yamamoto, H.; Nomachi, M.; Yasuda, K.; Matsuda, Y.; Murata, Y.; Kijimura, T.; Sano, H.; Sakai, T.; Kamiya, T.

2007-01-01

Using PIGE (TIARA, JAPAN) technique, we measured fluorine (F) uptake into the tooth enamel around a fluoride-containing material during caries progression using pH cycling. Class I cavities in the buccal surfaces of 6 extracted human teeth were drilled and filled with fluoride-containing material; a glass ionomer cement (Fuji IX(GC)). Three 300 μm sections through the material were obtained from each tooth. Two of these specimens were utilized to measure the F distribution in enamel adjacent to the material. A 1.7 MeV proton beam accelerated by the TIARA single-ended accelerator was delivered to a micro-beam apparatus. The beam spot size was about 1 μm with a beam current of about 100 pA. A nuclear reaction, 19 F(p, αγ) 16 0, was used to measure the F concentration and the gamma-rays from this reaction were detected with a 4' NaI detector. X-rays induced by proton were detected with a Si(Li) detector to measure calcium concentration and the beam intensity was monitored with the X-ray yield from a copper foil for quantitative analysis. After measurement of F uptake, all specimens were polished to a thickness of 120 μm. In order to simulate daily acid challenges occurring in the oral cavity, the pH cycling (pH6.8-pH4.5) was carried out for 1, 3 and 5 weeks, separately. The duration that the solution remained below pH 5.5 was 37 min per cycle. The cycles were repeated 6 times per day with 2 h interval between cycles, and the specimens were kept in remineralizing solution for the rest of pH cycle. After pH cycling, F and calcium distribution of each specimen was evaluated using PIGE technique. The F distribution of the specimens before pH cycling clearly showed the F uptake from fluoride-containing material into enamel adjacent to the material. After pH cycling, the caries progression in all specimens was observed by the image of transverse microradiography (TMR). The depth of caries and mineral loss progressed with increasing the duration of pH cycling, although

Fluorine uptake into human enamel around a fluoride-containing dental material during cariogenic pH cycling

Energy Technology Data Exchange (ETDEWEB)

Komatsu, H. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan)]. E-mail: kom@den.hokudai.ac.jp; Yamamoto, H. [Graduate School of Dentistry, Osaka University, 1-8 Yamada-Oka, Suita 565-0871 (Japan); Nomachi, M. [Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043 (Japan); Yasuda, K. [Wakasa wan Energy Research Center, 64-52-1 Hase, Tsuruga 914-0192 (Japan); Matsuda, Y. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Murata, Y. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Kijimura, T. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Sano, H. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Sakai, T. [Takasaki Advanced Radiation Research Institute, JAEA, 1233 Watanuki-machi, Takasaki 370-1292 (Japan); Kamiya, T. [Takasaki Advanced Radiation Research Institute, JAEA, 1233 Watanuki-machi, Takasaki 370-1292 (Japan)

2007-07-15

Using PIGE (TIARA, JAPAN) technique, we measured fluorine (F) uptake into the tooth enamel around a fluoride-containing material during caries progression using pH cycling. Class I cavities in the buccal surfaces of 6 extracted human teeth were drilled and filled with fluoride-containing material; a glass ionomer cement (Fuji IX(GC)). Three 300 {mu}m sections through the material were obtained from each tooth. Two of these specimens were utilized to measure the F distribution in enamel adjacent to the material. A 1.7 MeV proton beam accelerated by the TIARA single-ended accelerator was delivered to a micro-beam apparatus. The beam spot size was about 1 {mu}m with a beam current of about 100 pA. A nuclear reaction, {sup 19}F(p, {alpha}{gamma}){sup 16}0, was used to measure the F concentration and the gamma-rays from this reaction were detected with a 4' NaI detector. X-rays induced by proton were detected with a Si(Li) detector to measure calcium concentration and the beam intensity was monitored with the X-ray yield from a copper foil for quantitative analysis. After measurement of F uptake, all specimens were polished to a thickness of 120 {mu}m. In order to simulate daily acid challenges occurring in the oral cavity, the pH cycling (pH6.8-pH4.5) was carried out for 1, 3 and 5 weeks, separately. The duration that the solution remained below pH 5.5 was 37 min per cycle. The cycles were repeated 6 times per day with 2 h interval between cycles, and the specimens were kept in remineralizing solution for the rest of pH cycle. After pH cycling, F and calcium distribution of each specimen was evaluated using PIGE technique. The F distribution of the specimens before pH cycling clearly showed the F uptake from fluoride-containing material into enamel adjacent to the material. After pH cycling, the caries progression in all specimens was observed by the image of transverse microradiography (TMR). The depth of caries and mineral loss progressed with increasing the

Removal of hydrogen fluoride from uranium plant emissions

International Nuclear Information System (INIS)

Ramani, M.P.S.

1997-01-01

Uranium production technology involves the use of hydrogen fluoride at various stages. It is used in the production of uranium tetrafluoride as well as for the production of fluorine for the conversion of tetrafluoride to hexafluoride in isotopic enrichment plants. The sources of HF pollution in the industry, besides accidental spillages and leakages, are the final off-gases from the UF 4 production process or from the hydrogen reduction of hexafluoride (where such process is adopted), venting of tanks and reactors containing HF, safety pressure rupture discs as well as dust collection and ventilation systems

Studies in group IV organometallic chemistry XXX. Synthesis of compounds containing tin---titanium and tin---zirconium bonds

NARCIS (Netherlands)

Creemers, H.M.J.C.; Verbeek, F.; Noltes, J.G.

1968-01-01

Starting from the tetrakis(diethylamino) derivatives of titanium and zirconium and pheyltin hydrides six intermetalic compounds contianing up to nine tin and titanium(or zirconium) atoms have been obtained by hydrostannolysis type reactions.

Current status of fluoride volatility method development

Energy Technology Data Exchange (ETDEWEB)

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

2013-07-01

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

Recovery and Purification of Tin from Tailings from the Penouta Sn–Ta–Nb Deposit

Directory of Open Access Journals (Sweden)

Félix Antonio López

2018-01-01

Full Text Available A concentrate obtained from mining tailings containing mainly cassiterite and columbotantalite was reduced for the production of tin metal. The compounds CaCO3, Na2CO3, K2CO3, and borax were used as fluxes in the pyrometallurgical reduction smelting process, and graphite was employed as the reducing agent. The greatest recovery of Sn (>95% was obtained when using CaCO3 as the flux; the purity of Sn was 96%. A slag equivalent to 25% of the mass of the initial concentrate was produced during the recovery of the Sn. This contained 45% Nb2O5 and Ta2O5, adding extra value to the mine tailings. The tin metal ingot was purified by electrorefining involving a tin and H2SO4 electrolyte solution and a 101.9 A/m2 current applied for 148 h. Under these conditions, 90 wt % of the Sn in the ingot was recovered at a purity of 99.97%.

F-centers in alkaline-earth fluorides. Inadequacy of the muffin-tin approximation

International Nuclear Information System (INIS)

Oliveira, L.E.; Oliveira, P.M.; Maffeo, B.

1977-01-01

The SCF-MSXα (Self Consisting F-centers-Multiple Scattering Xα) method has been applied in the study of the electronic structure of F centers in CaF 2 , SrF 2 and BaF 2 . The predicted optical transition energies are in disagreement with the experimental data. An explanation for the discrepancy is provided showing the inadequacy of the spherical averaging of the potential within the muffin-tin approximation [pt

No calcium-fluoride-like deposits detected in plaque shortly after a sodium fluoride mouthrinse.

Science.gov (United States)

Vogel, G L; Tenuta, L M A; Schumacher, G E; Chow, L C

2010-01-01

Plaque 'calcium-fluoride-like' (CaF(2)-like) and fluoride deposits held by biological/bacterial calcium fluoride (Ca-F) bonds appear to be the source of cariostatic concentrations of fluoride in plaque fluid. The aim of this study was to quantify the amounts of plaque fluoride held in these reservoirs after a sodium fluoride rinse. 30 and 60 min after a 228 microg/g fluoride rinse, plaque samples were collected from 11 volunteers. Each sample was homogenized, split into 2 aliquots (aliquots 1 and 2), centrifuged, and the recovered plaque fluid combined and analyzed using microelectrodes. The plaque mass from aliquot 1 was retained. The plaque mass from aliquot 2 was extracted several times with a solution having the same fluoride, calcium and pH as the plaque fluid in order to extract the plaque CaF(2)-like deposits. The total fluoride in both aliquots was then determined. In a second experiment, the extraction completeness was examined by applying the above procedure to in vitro precipitates containing known amounts of CaF(2)-like deposits. Nearly identical fluoride concentrations were found in both plaque aliquots. The extraction of the CaF(2)-like precipitates formed in vitro removed more than 80% of these deposits. The results suggest that either CaF(2)-like deposits were not formed in plaque or, if these deposits had been formed, they were rapidly lost. The inability to form persistent amounts of CaF(2)-like deposits in plaque may account for the relatively rapid loss of plaque fluid fluoride after the use of conventional fluoride dentifrices or rinses. (c) 2010 S. Karger AG, Basel.

Fluoride exposure and indicators of thyroid functioning in the Canadian population: implications for community water fluoridation.

Science.gov (United States)

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

2017-10-01

There are concerns that altered thyroid functioning could be the result of ingesting too much fluoride. Community water fluoridation (CWF) is an important source of fluoride exposure. Our objectives were to examine the association between fluoride exposure and (1) diagnosis of a thyroid condition and (2) indicators of thyroid functioning among a national population-based sample of Canadians. We analysed data from Cycles 2 and 3 of the Canadian Health Measures Survey (CHMS). Logistic regression was used to assess associations between fluoride from urine and tap water samples and the diagnosis of a thyroid condition. Multinomial logistic regression was used to examine the relationship between fluoride exposure and thyroid-stimulating hormone (TSH) level (low/normal/high). Other available variables permitted additional exploratory analyses among the subset of participants for whom we could discern some fluoride exposure from drinking water and/or dental products. There was no evidence of a relationship between fluoride exposure (from urine and tap water) and the diagnosis of a thyroid condition. There was no statistically significant association between fluoride exposure and abnormal (low or high) TSH levels relative to normal TSH levels. Rerunning the models with the sample constrained to the subset of participants for whom we could discern some source(s) of fluoride exposure from drinking water and/or dental products revealed no significant associations. These analyses suggest that, at the population level, fluoride exposure is not associated with impaired thyroid functioning in a time and place where multiple sources of fluoride exposure, including CWF, exist. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Recovery of Tin and Nitric Acid from Spent Solder Stripping Solutions

International Nuclear Information System (INIS)

Ahn, Jae-Woo; Ryu, Seong-Hyung; Kim, Tae-young

2015-01-01

Spent solder-stripping solutions containing tin, copper, iron, and lead in nitric acid solution, are by-products of the manufacture of printed-circuit boards. The recovery of these metals and the nitric acid, for re-use has economic and environmental benefits. In the spent solder-stripping solution, a systematic method to determine a suitable process for recovery of valuable metals and nitric acid was developed. Initially, more than 90% of the tin was successfully recovered as high-purity SnO 2 by thermal precipitation at 80 ℃ for 3 hours. About 94% of the nitric acid was regenerated effectively from the spent solutions by diffusion dialysis, after which there remained copper, iron, and lead in solution. Leakage of tin through the anion-exchange membrane was the lowest (0.026%), whereas Pb-leakage was highest (4.26%). The concentration of the regenerated nitric acid was about 5.1 N.

Les peintures marines antisalissures à base de polymères organostanniques Antifouling Marine Paints Containing Organo-Tin Polymers

Directory of Open Access Journals (Sweden)

Dawans F.

2006-11-01

Full Text Available Le dépôt des salissures marines sur les ouvrages immergés est influencé par plusieurs facteurs et il entraîne des conséquences néfastes, en particulier pour la maintenance des supports de plates-formes de production du pétrole en mer et pour la consommation d'énergie requise pour la propulsion des navires. Divers moyens de lutte antisalissure ont été envisagés parmi lesquels les peintures marines antisalissures occupent une place de choix. Ces peintures contiennent, en général, un composé métallique toxique envers les organismes marins d'origine animale ou végétale et différents mécanismes d'action ont été proposés. Les dérivés organostanniques sont des agents biocides très efficaces et lorsqu'ils sont liés chimiquement sur un polymère, en particulier sous forme de greffons, on obtient un contrôle amélioré de leur lixiviation dans la phase aqueuse et par conséquent la durée de vie du revêtement antisalissure est prolongée. La synthèse de polymères comportant un cation organostannique toxique peut être effectuée, soit par la polymérisation ou la copolymérisation de monomères insaturés organostanniques, soit par la réaction chimique de composés organostanniques avec un substrat polymère comportant des groupes fonctionnels appropriés. Les avantages et les inconvénients de diverses formulations de peintures à base de dérivés organostanniques sont discutés. Marine fouling deposits on submerged structures are influenced by several factors and bring about harmful consequences, especially with regard to offshore oil-production platform structures and for the energy consumption required for ship propulsion. Various antifouling methods have been considered, including antifouling marine coatings in particular. Such paints generally contain a metallic compound which is toxic with regard to marine organisms of animal or vegetable origin, and various action mechanisms have been proposed. Organo-tin

Effect of fluoride pretreatment on the solubility of synthetic carbonated apatite.

Science.gov (United States)

Barry, A B; Zhuang, H; Baig, A A; Higuchi, W I

2003-03-01

The purpose of this research was to address the following question: How is the solubility of fluoride-pretreated carbonated apatite (CAP) in aqueous acidic media related to the equilibrium solution fluoride and/or the CAP adsorbed fluoride levels? A CAP sample prepared by a precipitation method at 70 degrees C containing approximately 6% carbonate was fluoride-treated (F adsorption from neutral aqueous solutions) to yield a approximately 1000 ppm F CAP and a approximately 3300 ppm F CAP. Metastable equilibrium solubility distributions were determined in acetate buffers at pH 5.0. Solution fluoride, calcium, phosphate, and pH were determined from the equilibrated solutions. The equilibrium solution fluoride levels were extremely low, e.g., as low as approximately 0.10 ppb to approximately 0.30 ppb at 50% dissolved for the two CAP preparations. The approximately 3300 ppm F CAP yielded a lower solubility than the approximately 1000 ppm F CAP (shift in the mean pKHAP value of 1.5-2 units). This can be attributed to the lower solution F(-) for the sample containing approximately 1000 ppm fluoride compared with the approximately 3300 ppm fluoride-containing CAP. These important findings suggest that a fluoride treatment simply may provide an adsorption fluoride depot for subsequent release, providing a solution fluoride effect upon the CAP solubility and not necessarily any intrinsic alteration of the mineral solubility.

The cariostatic mechanisms of fluoride

Directory of Open Access Journals (Sweden)

Kata Rošin-Grget

2013-11-01

Full Text Available This article discusses the possible cariostatic mechanisms of the action of fluoride. In the past, fluoride inhibition of caries was ascribed to reduced solubility of enamel due to incorporation of fluoride (F– into the enamel minerals. The present evidence from clinical and laboratory studies suggests that the caries-preventive mode of action of fluoride is mainly topical. There is convincing evidence that fluoride has a major effect on demineralisation and remineralisation of dental hard tissue. The source of this fluoride could either be fluorapatite (formed due to the incorporation of fluoride into enamel or calcium fluoride (CaF2-like precipitates, which are formed on the enamel and in the plaque after application of topical fluoride. Calcium fluoride deposits are protected from rapid dissolution by a phosphate –protein coating of salivary origin. At lower pH, the coating is lost and an increased dissolution rate of calcium fluoride occurs. The CaF2, therefore, act as an efficient source of free fluoride ions during the cariogenic challenge. The current evidence indicates that fluoride has a direct and indirect effect on bacterial cells, although the in vivo implications of this are still not clear. Conclusion. A better understanding of the mechanisms of the action of fluoride is very important for caries prevention and control. The effectiveness of fluoride as a cariostatic agent depends on the availability of free fluoride in plaque during cariogenic challenge, i.e. during acid production. Thus, a constant supply of low levels of fluoride in biofilm/saliva/dental interference is considered the most beneficial in preventing dental caries.

The cariostatic mechanisms of fluoride.

Science.gov (United States)

Rošin-Grget, Kata; Peroš, Kristina; Sutej, Ivana; Bašić, Krešimir

2013-11-01

This article discusses the possible cariostatic mechanisms of the action of fluoride. In the past, fluoride inhibition of caries was ascribed to reduced solubility of enamel due to incorporation of fluoride (F-) into the enamel minerals. The present evidence from clinical and laboratory studies suggests that the caries-preventive mode of action of fluoride is mainly topical. There is convincing evidence that fluoride has a major effect on demineralisation and remineralisation of dental hard tissue. The source of this fluoride could either be fluorapatite (formed due to the incorporation of fluoride into enamel) or calcium fluoride (CaF2)-like precipitates, which are formed on the enamel and in the plaque after application of topical fluoride. Calcium fluoride deposits are protected from rapid dissolution by a phosphate -protein coating of salivary origin. At lower pH, the coating is lost and an increased dissolution rate of calcium fluoride occurs. The CaF2, therefore, act as an efficient source of free fluoride ions during the cariogenic challenge. The current evidence indicates that fluoride has a direct and indirect effect on bacterial cells, although the in vivo implications of this are still not clear. A better understanding of the mechanisms of the action of fluoride is very important for caries prevention and control. The effectiveness of fluoride as a cariostatic agent depends on the availability of free fluoride in plaque during cariogenic challenge, i.e. during acid production. Thus, a constant supply of low levels of fluoride in biofilm/saliva/dental interference is considered the most beneficial in preventing dental caries. Copyright © 2013 by Academy of Sciences and Arts of Bosnia and Herzegovina.

Anticaries potential of commercial dentifrices as determined by fluoridation and remineralization efficiency.

Science.gov (United States)

Casals, Elias; Boukpessi, Tchilalo; McQueen, Christina M; Eversole, Sandy L; Faller, Robert V

2007-11-01

The aim of this in vitro study was to investigate fluoride uptake in human enamel after use of commercially available toothpastes containing different fluoride compounds, or combinations of fluoride actives formulated into a single product, as a means of determining the efficiency of each formula for delivering caries preventing fluoride to demineralized (caries active) enamel. Four test dentifrices and two controls were assessed and placed in groups as follows: Group 1: Lacer (Spain); Group 2: Positive control-USP Reference Standard 1100 ppm F; Group 3: Fluocaril Bi-Fluoré 250 (France); Group 4: Colgate Fluor Active (Denmark); Group 5: Elmex (France); and Group 6: A placebo (formulated the same as the USP Reference Standard toothpaste with the exception that it contained < 1 ppm F). Cores 3 mm in diameter were removed from erupted human enamel specimens (extracted by local oral surgeons for orthodontic reasons) and stored in 1% Thymol solution prior to use. They were ground and polished to remove the natural fluoride rich enamel layer, then exposed to a demineralization solution, and assessed for surface microhardness to enable randomization for use in the study. Each group of five specimens underwent a daily pH cycling procedure that involved exposure to pooled human saliva (refreshed three times daily). The groups were then exposed to dentifrice slurries four times daily for one minute per exposure and to a demineralization solution for three hours. The cycling procedure was repeated for five days. Specimens were again analyzed for surface microhardness and fluoride uptake upon completion of five days of treatment. Average surface hardness: Groups 2 and 3 showed a statistically significant greater (p<0.05) change indicating greater remineralization compared to all other groups. The average change was 23.45 for Group 2 and 22.65 for Group 3. All other groups had changes ranging from 4.25-8.62. No other statistically significant differences were observed between

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

African Journals Online (AJOL)

EJIRO

conditions, the fluoride removal efficiency from Kuhbonan water by 2.8 mg/L fluoride was 74.64%. Eventually ... industrial wastewater containing fluoride is a key ..... solution using silica ceramic: Adsorption kinetics and equilibrium studies.

Properties of sodium borosilicate glasses/Al2O3 sintered composites containing fluorides. Gan Fukkabutsu hokei san natoriumu garasu to alumina fukugo shoketsutai no bussei

Energy Technology Data Exchange (ETDEWEB)

Ryu, Bonggi; Yasui, I [The Univ. of Tokyo, Tokyo (Japan). Inst. of Industrial Science

1993-06-01

Glass/alumina sintered composites were synthesized from sodium borosilicate glass powder containing fluorides like AlF3 and NaF3, and Al2O3, and change in material properties was examined. Glass compositions of B2O3 and Na2O greatly affected the crystal phase and material properties. Nephelin crystal phase was extracted by the reaction of Na2O, NaF2, SiO2 and Al2O3 when B/Na<1. Coefficient of thermal expansion increased with the increase of Na/Si ratio. The residual amount of fluorides of sintered materials in nitrogen atmosphere was higher than that of air, and differed with the type of fluoride. The F[sup -] of NaF is bonded with Si of glass network and forms quiet stable glass structure, whereas, F[sup -] of AlF3 reacts with Si[sup 4+] forming SiF4 which is vaporized. Sintering temperature and dielectric constant of sintered materials containing fluoride was lower than the sintered materials without fluorides addition, however, at a sintering temperature range of 100 to 150[degree]C, it was inferred that this was because of the increase in voids due to SiF4 formed in the reaction. 16 refs., 17 figs., 3 tabs.

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

OpenAIRE

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

2013-01-01

Although fluoride is plentiful in the environment and is commonly used at high concentrations in oral hygiene products, little has been known about how biological systems overcome the toxic effects of this anion. We demonstrate that a protein called FEX in many fungi is essential for cell survival in the presence of high fluoride concentrations. The protein is required for the rapid expulsion of cytoplasmic fluoride, indicating that many eukaryotic species that carry FEX genes likely avoid fl...

Galvanic Corrosion of and Ion Release from Various Orthodontic Brackets and Wires in a Fluoride-containing Mouthwash.

Science.gov (United States)

Tahmasbi, Soodeh; Ghorbani, Mohammad; Masudrad, Mahdis

2015-01-01

Background and aims. This study compared the galvanic corrosion of orthodontic wires and brackets from various manufacturers following exposure to a fluoride mouthwash. Materials and methods. This study was conducted on 24 lower central incisor 0.022" Roth brackets of four different commercially available brands (Dentaurum, American Orthodontics, ORJ, Shinye). These brackets along with stainless steel (SS) or nickel-titanium (NiTi) orthodontic wires (0.016", round) were immersed in Oral-B mouthwash containing 0.05% sodium fluoride for 28 days. The electric potential (EP) difference of each bracket-wire couple was measured with a Saturated Calomel Reference Electrode (Ag/AgCl saturated with KCl) via a voltmeter. The ions released in the electrolyte weremeasured with an atomic absorption spectrometer. All the specimens were assessed under a stereomicroscope and specimens with corrosion were analyzed with scanning electron microscopy (SEM). Data were analyzed using ANOVA. Results. The copper ions released from specimens with NiTi wire were greater than those of samples containing SS wire. ORJ brackets released more Cu ions than other samples. The Ni ions released from Shinye brackets were significantly more than those of other specimens (P brackets coupled with NiTi wires was higher than that of brackets coupled with SS wires. Light and electron microscopic observations showed greater corrosion of ORJ brackets. Conclusion. In fluoride mouthwash, Shinye and ORJ brackets exhibited greater corrosion than Dentaurum and American Orthodontics brackets. Stainless steel brackets used with NiTi wires showed greater corrosion and thus caution is recommended when using them.

Application of Titanium Compounds to Reduce Fluoride Ion in Water Resources with High Fluoride Ion Contents

Directory of Open Access Journals (Sweden)

Fariborz Riahi

2005-06-01

Full Text Available The present work describes studies on the sorption of fluoride ions from water by titanium compounds used in water treatment to reduce fluoride content in water resources. There are different methods of reducing fluoride ion in water, each associated with specific problems such as secondary contamination, environmental contamination, high costs, or the need for primary and secondary treatment. In this study, application of titanium sulfate and Metatitanic acid produced from titanium ore concentrate (ileminite is investigated in the removal of fluoride ion and the possibility of complete purification of fluorine containing wastewater is examined to determine the optimal conditions. Metatitanic acid has a great sorption property for fluoride ion. Also titanium sulfate is a suitable and more effective material for this purpose. Efficiency of this material in reducing fluoride ion content is 99.9% and it is possible to refresh sorbet material for reuse without problems arising from Ti+4 ion contamination.

Anhydrous hydrogen fluoride electrolyte battery. [Patent application

Science.gov (United States)

Not Available

1972-06-26

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

Fluoride absorption: independence from plasma fluoride levels

International Nuclear Information System (INIS)

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

1986-01-01

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

Fluoride remediation using floating macrophytes

Directory of Open Access Journals (Sweden)

Naba Kumar Mondal

2014-04-01

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

Evaluation of the remineralization capacity of CPP-ACP containing fluoride varnish by different quantitative methods

Directory of Open Access Journals (Sweden)

Selcuk SAVAS

Full Text Available ABSTRACT Objective The aim of this study was to evaluate the efficacy of CPP-ACP containing fluoride varnish for remineralizing white spot lesions (WSLs with four different quantitative methods. Material and Methods Four windows (3x3 mm were created on the enamel surfaces of bovine incisor teeth. A control window was covered with nail varnish, and WSLs were created on the other windows (after demineralization, first week and fourth week in acidified gel system. The test material (MI Varnish was applied on the demineralized areas, and the treated enamel samples were stored in artificial saliva. At the fourth week, the enamel surfaces were tested by surface microhardness (SMH, quantitative light-induced fluorescence-digital (QLF-D, energy-dispersive spectroscopy (EDS and laser fluorescence (LF pen. The data were statistically analyzed (α=0.05. Results While the LF pen measurements showed significant differences at baseline, after demineralization, and after the one-week remineralization period (p0.05. With regards to the SMH and QLF-D analyses, statistically significant differences were found among all the phases (p<0.05. After the 1- and 4-week treatment periods, the calcium (Ca and phosphate (P concentrations and Ca/P ratio were higher compared to those of the demineralization surfaces (p<0.05. Conclusion CPP-ACP containing fluoride varnish provides remineralization of WSLs after a single application and seems suitable for clinical use.

A novel UV-photolysis approach with acetone and isopropyl alcohol for the rapid determination of fluoride in organofluorine-containing drugs by spectrophotometry.

Science.gov (United States)

Mullapudi, Venkata Balarama Krishna; Dheram, Karunasagar

2018-01-01

A UV photolysis decomposition (UVPD) method for the determination of fluoride in fluorine containing pharmaceuticals by spectrophotometry is reported. It is based on the use of high intensity UV-irradiation in the presence of a digesting solution comprising a mixture of acetone and isopropanol. For the optimization of the UVPD procedure, three bulk drugs (levofloxacin, nebivolol and efavirenz) were chosen as representatives of three diverse compounds containing a single fluorine atom, two fluorine atoms, and trifluoromethyl groups respectively. Operational conditions of the UVPD method, such as concentration and volume of reagents (acetone and isopropyl alcohol), and UV irradiation time (1-6 minutes) were optimized. The efficiency of digestion was evaluated by the determination of fluoride in sample digests. Using the developed method, it was possible for complete conversion of the organofluoride to free fluoride ion for its subsequent determination by spectrophotometry based on bleaching of Zr-xylenol orange-color complex. Quantitative recovery (>98%) of the fluorine in the drug samples could be achieved using a mixture of 2% acetone + 2% isopropyl alcohol + 0.003% Na 2 CO 3 in just 5 minutes of UV irradiation, which can be considered an important aspect considering the difficulties involved in the cleavage of the CF bond. Accuracy was evaluated by comparison of results obtained by the UVPD method with the values estimated using formula weight of the compound and no statistical difference was observed between the results. Therefore, the proposed method is suitable for application in routine analysis of fluoride in organofluorine-containing drugs. Copyright © 2016. Published by Elsevier B.V.

Phosphorylated and nucleotide sugar metabolism in relation to cell wall production in Avena coleoptiles treated with fluoride and peroxyacetyl nitrate

International Nuclear Information System (INIS)

Gordon, W.C.; Ordin, L.

1972-01-01

Coleoptile sections of Avena sativa L. were pretreated with sodium fluoride or peroxyacetyl nitrate at levels which inhibit auxin-induced growth but did not affect glucose-uptake or CO production when postincubated for 30 minutes in a 14 C-glucose medium without auxin. Labeling of metabolites involved in cell wall synthesis was measured. Peroxyacetyl nitrate decreased labeling, and it was concluded that the pool size of uridine diphosphoglucose, sucrose, and cell wall polysaccharides decreased compared to control. The changes suggest that peroxyacetyl nitrate inactivated sucrose and cell wall synthesizing enzymes including cellulose synthetase and decreased cell growth by inhibiting production of cell wall constituents. Fluoride treatment had no effect on production of cell wall polysaccharides, with or without indoleacetic acid stimulation of growth. The only change after fluoride treatment was a decrease in uridine diphosphoglucose during incubation without indoleacetic acid, a decrease that disappeared when indoleacetic acid was present. It was concluded that some other aspect of cell wall metabolism, not determined here, was involved in fluoride-induced inhibition of growth. 16 references, 3 figures, 2 tables

Galvanic Corrosion of and Ion Release from Various Orthodontic Brackets and Wires in a Fluoride-containing Mouthwash

Directory of Open Access Journals (Sweden)

Soodeh Tahmasbi

2015-09-01

Full Text Available Background and aims. This study compared the galvanic corrosion of orthodontic wires and brackets from various man-ufacturers following exposure to a fluoride mouthwash. Materials and methods. This study was conducted on 24 lower central incisor 0.022” Roth brackets of four different commercially available brands (Dentaurum, American Orthodontics, ORJ, Shinye. These brackets along with stainless steel (SS or nickel-titanium (NiTi orthodontic wires (0.016", round were immersed in Oral-B mouthwash containing 0.05% sodium fluoride for 28 days. The electric potential (EP difference of each bracket-wire couple was measured with a Satu-rated Calomel Reference Electrode (Ag/AgCl saturated with KCl via a voltmeter. The ions released in the electrolyte weremeasured with an atomic absorption spectrometer. All the specimens were assessed under a stereomicroscope and speci-mens with corrosion were analyzed with scanning electron microscopy (SEM. Data were analyzed using ANOVA. Results. The copper ions released from specimens with NiTi wire were greater than those of samples containing SS wire. ORJ brackets released more Cu ions than other samples. The Ni ions released from Shinye brackets were significantly more than those of other specimens (P < 0.05. Corrosion rate of brackets coupled with NiTi wires was higher than that of brack-ets coupled with SS wires. Light and electron microscopic observations showed greater corrosion of ORJ brackets. Conclusion. In fluoride mouthwash, Shinye and ORJ brackets exhibited greater corrosion than Dentaurum and American Orthodontics brackets. Stainless steel brackets used with NiTi wires showed greater corrosion and thus caution is recom-mended when using them.

Fluoridation Basics

Science.gov (United States)

... return on investment for community water fluoridation (including productivity losses) ranged from $4 in small communities of ... National Center for Chronic Disease Prevention and Health Promotion Email Recommend Tweet YouTube Instagram Listen Watch RSS ...

Conflict minerals in the compute sector: estimating extent of tin, tantalum, tungsten, and gold use in ICT products.

Science.gov (United States)

Fitzpatrick, Colin; Olivetti, Elsa; Miller, Reed; Roth, Richard; Kirchain, Randolph

2015-01-20

Recent legislation has focused attention on the supply chains of tin, tungsten, tantalum, and gold (3TG), specifically those originating from the eastern part of the Democratic Republic of Congo. The unique properties of these so-called “conflict minerals” lead to their use in many products, ranging from medical devices to industrial cutting tools. This paper calculates per product use of 3TG in several information, communication, and technology (ICT) products such as desktops, servers, laptops, smart phones, and tablets. By scaling up individual product estimates to global shipment figures, this work estimates the influence of the ICT sector on 3TG mining in covered countries. The model estimates the upper bound of tin, tungsten, tantalum, and gold use within ICT products to be 2%, 0.1%, 15%, and 3% of the 2013 market share, respectively. This result is projected into the future (2018) based on the anticipated increase in ICT device production.

Study of the behaviour of some heavy elements in solvents containing hydrogen fluoride

International Nuclear Information System (INIS)

Tarnero, M.

1967-01-01

The anhydrous liquid mixtures: dinitrogen tetroxide-hydrogen fluoride and antimony pentafluoride-hydrogen fluoride were studied as solvents for heavy elements interesting nuclear energy: uranium, thorium, zirconium and for some of their compounds. For N 2 O 4 -HF mixtures, electric conductivity measurements and liquid phase infrared spectra were also obtained. Uranium and zirconium tetrafluoride are much more soluble in N 2 O 4 -HF mixtures than in pure hydrogen fluoride. Uranium dissolved in these mixtures is pentavalent. In SbF 5 -HF mixtures, uranium dissolves with hydrogen evolution and becomes trivalent. The solid compound resulting from the dissolution is a fluoro-antimonate: U(SbF 6 ) 3 . (author) [fr

Fluoride varnish or fluoride mouth rinse?

DEFF Research Database (Denmark)

Keller, M K; Klausen, BJ; Twetman, S

2016-01-01

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

Alimentary fluoride intake in preschool children

Directory of Open Access Journals (Sweden)

Lencova Erika

2011-10-01

. These results showed that in preschool children, when trying to maximize the benefit of fluoride in caries prevention and to minimize its risk, caution should be exercised when giving advice on the fluoride containing components of child's diet or prescribing fluoride supplements.

NASA GSFC Tin Whisker Homepage http://nepp.nasa.gov/whisker

Science.gov (United States)

Shaw, Harry

2000-01-01

The NASA GSFC Tin Whisker Homepage provides general information and GSFC Code 562 experimentation results regarding the well known phenomenon of tin whisker formation from pure tin plated substrates. The objective of this www site is to provide a central repository for information pertaining to this phenomenon and to provide status of the GSFC experiments to understand the behavior of tin whiskers in space environments. The Tin Whisker www site is produced by Code 562. This www site does not provide information pertaining to patented or proprietary information. All of the information contained in this www site is at the level of that produced by industry and university researchers and is published at international conferences.

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

International Nuclear Information System (INIS)

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

1997-02-01

The authors have used thermodynamic modeling to examine the reaction of calcium fluoride (CaF 2 ) and magnesium fluoride (MgF 2 ) with water (H 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 2 is found at 1,000 C and a ratio of 40 moles of H 2 O per 1 mole of MgF 2 . For CaF 2 , temperatures as high as 1,400 C are required for complete conversion at a corresponding mole ratio of 40 moles of H 2 O per 1 mole of CaF 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 2 and MgF 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

Review on fluoride-releasing restorative materials--fluoride release and uptake characteristics, antibacterial activity and influence on caries formation.

Science.gov (United States)

Wiegand, Annette; Buchalla, Wolfgang; Attin, Thomas

2007-03-01

The purpose of this article was to review the fluoride release and recharge capabilities, and antibacterial properties, of fluoride-releasing dental restoratives, and discuss the current status concerning the prevention or inhibition of caries development and progression. Information from original scientific full papers or reviews listed in PubMed (search term: fluoride release AND (restorative OR glass-ionomer OR compomer OR polyacid-modified composite resin OR composite OR amalgam)), published from 1980 to 2004, was included in the review. Papers dealing with endodontic or orthodontic topics were not taken into consideration. Clinical studies concerning secondary caries development were only included when performed in split-mouth design with an observation period of at least three years. Fluoride-containing dental materials show clear differences in the fluoride release and uptake characteristics. Short- and long-term fluoride releases from restoratives are related to their matrices, setting mechanisms and fluoride content and depend on several environmental conditions. Fluoride-releasing materials may act as a fluoride reservoir and may increase the fluoride level in saliva, plaque and dental hard tissues. However, clinical studies exhibited conflicting data as to whether or not these materials significantly prevent or inhibit secondary caries and affect the growth of caries-associated bacteria compared to non-fluoridated restoratives. Fluoride release and uptake characteristics depend on the matrices, fillers and fluoride content as well as on the setting mechanisms and environmental conditions of the restoratives. Fluoride-releasing materials, predominantly glass-ionomers and compomers, did show cariostatic properties and may affect bacterial metabolism under simulated cariogenic conditions in vitro. However, it is not proven by prospective clinical studies whether the incidence of secondary caries can be significantly reduced by the fluoride release of

The 1/4 technical scale, continuous process of obtaining the ceramic uranium dioxide from ammonium polyuranates containing fluoride

International Nuclear Information System (INIS)

Wlodarski, R.

1977-01-01

Based on the laboratory results, the 1/4 technical apparatus for the continuous reduction and defluorination of ammonium polyuranate containing fluoride was designed and constructed. The possibility of obtaining the ceramic uranium dioxide in a continuous process has been confirmed. The main part of the apparatus used in this process was the horizontal tubular oven with the extruder transporting material. (author)

Acute toxicity of uranium hexafluoride, uranyl fluoride and hydrogen fluoride

International Nuclear Information System (INIS)

Just, R.A.

1988-01-01

Uranium hexafluoride (UF 6 ) released into the atmosphere will react rapidly with moisture in the air to form the hydrolysis products uranyl fluoride (UO 2 F 2 ) and hydrogen fluoride (HF). Uranium compounds such as UF 6 and UO 2 F 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 6 , UO 2 F 2 , and HF. 4 refs., 2 figs., 5 tabs

Fluorine analysis of human enamel around fluoride-containing materials under different pH-cycling by {mu}-PIGE/PIXE system

Energy Technology Data Exchange (ETDEWEB)

Komatsu, H., E-mail: kom@den.hokudai.ac.jp [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Yamamoto, H. [Graduate School of Dentistry, Osaka University, 1-8 Yamada-Oka, Suita 565-0871 (Japan); Matsuda, Y.; Kijimura, T.; Kinugawa, M.; Okuyama, K. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Nomachi, M. [Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043 (Japan); Yasuda, K. [Wakasa Wan Energy Research Center, 64-52-1 Hase, Tsuruga 914-0192 (Japan); Satoh, T. [Advanced Radiation Technology, TARRI, JAEA, 1233 Watanuki-Machi, Takasaki 370-1292 (Japan); Oikawa, S. [National Institute of Radiological Science, 4-9-1, Anagawa, Inage-ku, Chiba 263-8555 (Japan)

2011-10-15

The caries preventive effect of fluoride-containing materials (FCMs) might depend on the caries risk of the individuals. Two pairs of demineralizing and remineralizing solutions of pH-cycling were prepared for simulating low and high caries risk. The purpose of this study was to determine fluorine (F) uptake into human enamel around FCMs under different pH-cycling using the in-air {mu}-PIGE/PIXE system. Fluoride-containing glass ionomer cement (Fuji IX{sub GP} FAST CAPSULE (FN)), and composite resin (BEAUTIFIL II with FLUORO BOND SHAKE ONE (BS)) were used in this study. The pH-cycling (pH 6.8-4.5) was carried out for 5 weeks. After pH-cycling, the caries progression was analyzed using transverse micro-radiography (TMR). The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the PIGE/PIXE system. From TMR analysis, there was a difference in caries risk between the two kinds of pH-cycling. Although the caries preventive effect of BS and FN was confirmed at low risk, the effect at high risk was confirmed for FN only. From the analysis of the fluorine uptake in the outer 200 {mu}m of the lesion we concluded that there was no significant difference between the pH-cycling solutions. However, we found different fluorine concentrations in the enamel for the two FCMs. The decreased caries progression under high risk for FN indicated that an adequate amount of fluorine supplied from the material is required at higher caries risk. It was confirmed that the caries preventive effect of FCM depends on the caries risk. The fluorine analysis of teeth under various pH-cycling conditions gives information to evaluate the caries preventive effect of fluoride-containing materials according to the caries risk.

Fluorine analysis of human enamel around fluoride-containing materials under different pH-cycling by μ-PIGE/PIXE system

International Nuclear Information System (INIS)

Komatsu, H.; Yamamoto, H.; Matsuda, Y.; Kijimura, T.; Kinugawa, M.; Okuyama, K.; Nomachi, M.; Yasuda, K.; Satoh, T.; Oikawa, S.

2011-01-01

The caries preventive effect of fluoride-containing materials (FCMs) might depend on the caries risk of the individuals. Two pairs of demineralizing and remineralizing solutions of pH-cycling were prepared for simulating low and high caries risk. The purpose of this study was to determine fluorine (F) uptake into human enamel around FCMs under different pH-cycling using the in-air μ-PIGE/PIXE system. Fluoride-containing glass ionomer cement (Fuji IX GP FAST CAPSULE (FN)), and composite resin (BEAUTIFIL II with FLUORO BOND SHAKE ONE (BS)) were used in this study. The pH-cycling (pH 6.8-4.5) was carried out for 5 weeks. After pH-cycling, the caries progression was analyzed using transverse micro-radiography (TMR). The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the PIGE/PIXE system. From TMR analysis, there was a difference in caries risk between the two kinds of pH-cycling. Although the caries preventive effect of BS and FN was confirmed at low risk, the effect at high risk was confirmed for FN only. From the analysis of the fluorine uptake in the outer 200 μm of the lesion we concluded that there was no significant difference between the pH-cycling solutions. However, we found different fluorine concentrations in the enamel for the two FCMs. The decreased caries progression under high risk for FN indicated that an adequate amount of fluorine supplied from the material is required at higher caries risk. It was confirmed that the caries preventive effect of FCM depends on the caries risk. The fluorine analysis of teeth under various pH-cycling conditions gives information to evaluate the caries preventive effect of fluoride-containing materials according to the caries risk.

Directly smelted lead-tin alloys: A historical perspective

Science.gov (United States)

Dube, R. K.

2010-08-01

This paper discusses evidence related to the genesis and occurrence of mixed lead-tin ore deposit consisting of cassiterite and the secondary minerals formed from galena. These evidences belong to a very long time period ranging from pre-historic to as late as the nineteenth century a.d. This type of mixed ore deposits was smelted to prepare lead-tin alloys. The composition of the alloy depended on the composition of the starting ore mixture. A nineteenth century evidence for the production of directly smelted lead-tin alloys in southern Thailand is discussed. A unique and rather uncommon metallurgical terminology in Sanskrit language— Nāgaja—was introduced in India for the tin recovered from impure lead. This suggests that Indians developed a process for recovering tin from lead-tin alloys, which in all probability was based on the general principle of fire refining. It has been shown that in the context of India the possibility of connection between the word Nāgaja and the directly smelted lead-tin alloys cannot be ruled out.

The effect of CPP-ACP containing fluoride on Streptococcus mutans adhesion and enamel roughness

Directory of Open Access Journals (Sweden)

Yulita Kristanti

2013-12-01

Full Text Available Background: Direct contact between the bleaching agent and the enamel surface results in demineralization, alteration in surface roughness and bacterial adhesion. Many studies try to minimize this side effect through different way. Purpose: The aim of this study was to determined the effect of Calcium Phospho Peptide-Amorphous Calcium Phosphate (CPP-ACP containing fluoride application before and after bleaching procedure on the adhesion of S. Mutans and enamel roughness. Methods: The samples were 6 teeth which were divided into 4 groups, and each tooth was cut into four pieces. Group A and C were treated with CPP-ACP after bleaching, while group B and D were treated with CPP-ACP before and after bleaching. CPP-ACP used in group C and D was the one that contain fluoride. After treatment, all samples were sterilized, immersed in steril human saliva for one hour, then immersed into S. mutans suspension of 108 CFU. Samples were incubated overnight. On the next day the samples were put into steril BHI and vortexed for one minute to detach the bacteria. Fifteen ml BHI containing bacteria was poured into TYS agar then incubated 37°Cfor 48 hours. Bacterial colony was counted with colony counter. The SEM examination was done on all samples. Results: Application of desensitizing agent reduced the S.mutans adhesion significantly among groups (p<0.05 except between group A and C. SEM evaluation revealed significant differences among groups. Conclusion: The application of CPP-ACP containing fluoride before and after bleaching was effective to reduce the accumulation of S.mutans colony and enamel roughness.Latar belakang: Kontak langsung antara bahan bleaching dan permukaan enamel menyebabkan demineralisasi, perubahan kekasaran permukaan dan berpengaruh terhadap banyaknya bakteri Streptococcus mutans (S. mutans yang melekat. Banyak peneliti mencoba meminimalkan efek samping ini dengan cara yang beragam. Tujuan: Penelitian ini bertujuan untuk meneliti efek

Adverse effects of fluoride towards thyroid hormone metabolism

Directory of Open Access Journals (Sweden)

Enggar Abdullah Idris MZ

2008-03-01

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

Conversion electron Moessbauer spectroscopic studies on the chemical states of surface layers of corroded tin plates and tin-coated iron plates

International Nuclear Information System (INIS)

Kato, Akinori; Endo, Kazutoyo; Sano, Hirotoshi

1980-01-01

By means of the conversion electron Moessbauer spectroscopy (CEMS), we studied surface layers of ''tin'' plates and tin-coated iron plates corroded by various acids. Transmission Moessbauer spectra and X-ray diffraction patterns were also measured. Metastannic acid was formed, when the ''tin'' plate was corroded by nitric acid solution. In corrosion by phosphoric acid solution, the X-ray diffractometry revealed the formation of tin(IV) pyrophosphate. In corrosion by various organic acid solutions, the formation of oxides was identified by the 119 Sn CEMS, but not by the X-ray diffractometry because of the too thin corrosion layer. In corrosion of tin-coated iron plates, maleic acid, malonic acid, formic acid, and oxalic acid were used. It was determined by CEMS that the corrosion products caused by these acids were tin(IV) oxides, although they could not be identified by the X-ray diffractometry. CEMS also confirmed that the surface of uncorroded tin-coated iron plate was already oxidized by air. Colorimetric determinations of Sn and Fe dissolved from tin-coated iron plates to various acid solutions confirmed that maleic acid had the strongest corrosion effect among the organic acids studied. (author)

Bond durability of adhesives containing modified-monomer with/without-fluoride after aging in artificial saliva and under intrapulpal pressure simulation.

Science.gov (United States)

El-Deeb, H A; Al Sherbiney, H H; Mobarak, E H

2013-01-01

To evaluate the dentin bond strength durability of adhesives containing modified-monomer with/without-fluoride after storage in artificial saliva and under intrapulpal pressure simulation (IPPS). The occlusal enamel of 48 freshly extracted teeth was trimmed to expose midcoronal dentin. Roots were sectioned to expose the pulp chamber and to connect the specimens to the pulpal-pressure assembly. Specimens were assigned into four groups (n=12) according to adhesive system utilized: a two-step etch-and-rinse adhesive system (SB, Adper Single Bond 2, 3M ESPE), a two-step self-etch adhesive system (CSE, Clearfil SE Bond, Kuraray Medical Inc), and two single-step self-etch adhesives with the same modified monomer (bis-acrylamide)-one with fluoride (AOF, AdheSE One F, Ivoclar-Vivadent) and the other without (AO, AdheSE One, Ivoclar-Vivadent). Bonding was carried out while the specimens were subjected to 15-mm Hg IPPS. Resin composite (Valux Plus, 3M ESPE) buildups were made. After curing, specimens were aged in artificial saliva and under 20-mm Hg IPPS at 37°C in a specially constructed incubator either for 24 hours or six months prior to testing. Bonded specimens (n=6/group) were sectioned into sticks (n=24/group) with a cross section of 0.9 ± 0.01 mm(2) and subjected to microtensile bond strength (μTBS) testing using a universal testing machine. Data were statistically analyzed using two-way analysis of variance (ANOVA) with repeated measures, one-way ANOVA tests, and a t-test (partificial saliva and under IPPS, yet these values remained significantly higher than those for the other two adhesives with modified monomers. There was no significant difference in the bond strength values between fluoride-containing and fluoride-free self-etch adhesive systems (AOF and AO) after 24 hours or six months. Modes of failure were mainly adhesive and mixed. Based on the results of this study, 1) Fluoride addition did not affect dentin bond durability; and 2) despite the fact that

Fluoride salts and container materials for thermal energy storage applications in the temperature range 973 - 1400 K

Science.gov (United States)

Misra, Ajay K.; Whittenberger, J. Daniel

1987-01-01

Multicomponent fluoride salt mixtures were characterized for use as latent heat of fusion heat storage materials in advanced solar dynamic space power systems with operating temperatures in the range of 973 to 1400 K. The melting points and eutectic composition for many systems with published phase diagrams were verified, and several new eutectic compositions were identified. Additionally, the heats of fusion of several binary and ternary eutectics and congruently melting intermediate compounds were measured by differential scanning calorimetry. The extent of corrosion of various metals by fluoride melts was estimated from thermodynamic considerations, and equilibrium conditions inside a containment vessel were calculated as functions of the initial moisture content of the salt and free volume above the molten salt. Preliminary experimental data on the corrosion of commercial, high-temperature alloys in LiF-19.5CaF2 and NaF-27CaF2-36MgF2 melts are presented and compared to the thermodynamic predictions.

Comparative evaluation of fluoride release and recharge of pre-reacted glass ionomer composite and nano-ionomeric glass ionomer with daily fluoride exposure: An in vitro study

Directory of Open Access Journals (Sweden)

Jayanthi Mungara

2013-01-01

Full Text Available Aim: This in vitro study was designed to investigate the effects of daily fluoride exposures on fluoride release and recharge by prereacted glass ionomer (PRG composite and nano-ionomeric glass ionomer. Materials and Methods: Seventy-two specimens (36 of each material were prepared and by placing the restorative materials into Teflon mold. Each specimen was subjected to one of three daily treatments (n = 12: (1 No fluoride treatment (control; (2 application of a fluoride dentifrice (1,000 ppm once daily; and (3 the same regimen as (2, plus immersion in a 0.05% sodium fluoride (NaF mouth rinse (225 ppm immediately following the dentifrice application. Specimens were suspended in a storage vial containing 10 ml demineralizing solution for 6 h and transferred to a new test tube containing 10 ml remineralizing solution for 18 h. Fluoride treatments of the specimens were completed every day prior to their immersion in the demineralizing solution. Media solutions were buffered with equal volumes of total ionic strength adjustment buffer (TISAB II; fluoride levels were measured using a digital ion analyzer and fluoride electrode throughout the 21 day duration of the experiment. Results: Nano-ionomeric glass ionomer showed a better amount of fluoride release than PRG composite irrespective of the fluoride treatment supplementation (P < 0.01. Additional fluoride supplementation improved fluoride release and recharge ability for both the materials when compared to their respective control groups. The fluoride recharge for both materials did not show any sustained pattern of release. Conclusion: Nano-ionomeric glass ionomer demonstrated a greater ability to release and recharge compared with that of PRG composite.

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

International Nuclear Information System (INIS)

Cuttress, T.W.; Suckling, G.W.; Gao, J.; Coote, G.E.

1996-01-01

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

EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2013 . Scientific opinion on Dietary Reference Values for fluoride

DEFF Research Database (Denmark)

Tetens, Inge

Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies (NDA) derived Dietary Reference Values (DRVs) for fluoride, which are provided as Adequate Intake (AI) from all sources, including non-dietary sources. Fluoride is not an essential nutrient...... and adults, including pregnant and lactating women. For pregnant and lactating women, the AI is based on the body weight before pregnancy and lactation. Reliable and representative data on the total fluoride intake of the European population are not available. © European Food Safety Authority, 2013...

Lipopolysaccharide and Lipoteichoic Acid Virulence Deactivation by Stannous Fluoride.

Science.gov (United States)

Haught, Chris; Xie, Sancai; Circello, Ben; Tansky, Cheryl S; Khambe, Deepa; Klukowska, Malgorzata; Huggins, Tom; White, Donald J

2016-09-01

Oral bacterial pathogens promote gingivitis and periodontal disease. Bacterial endotoxins, also known as lipopolysaccharides (LPSs) and lipoteichoic acids (LTAs), are known to enhance bacterial pathogenicity through binding with Toll-like receptors (TLRs), a group of pattern recognition receptors critical to the activation of innate immunity, that are expressed on host cells. Both LPS and LTA contain lipophilic domains and anionic charges that may be susceptible to reactivity with stannous fluoride, a commonly used ingredient clinically proven for the treatment and prevention of gingivitis. This study examined the effects of stannous fluoride on Toll-like receptor activation in response to bacterially derived LPS and LTA in select cell lines and secretion of inflammatory cytokines from human primary peripheral monocytes likewise exposed to LPS. TLR4 and TLR2 transfected HEK293 cells and THP1-Dual™ cells were exposed to bacterial LPS and LTA in the presence of increasing concentrations of stannous fluoride. Gene expression was assessed by measurement of secreted embryonic alkaline phosphatase (SEAP) reporter gene for HEK293 cells and SEAP and luciferase for THP-1 cells. Cell viability was confirmed using PrestoBlue. Human primary monocytes were treated with LPS with various concentrations of supplemented stannous fluoride, and cytokine expression was directly measured. Stannous fluoride inhibited gene expression response of TLR4 and TLR2 in HEK293 cells and THP1-Dual™ cells in a dose response fashion, producing complete inhibition at micromolar concentrations. The addition of stannous fluoride suppressed production of TNF-a, IFN-g, IL12p70, IL10, IL-1b, IL2, and IL-6, and also increased secretion of Il-8 in dose response fashion. Viability assays confirmed no effects of LPS or stannous fluoride on viability of HEK293, THP-1, and primary human monocytes. These results support the potential for stannous fluoride to provide clinical gingivitis benefits by directly

Fluoride release from fluoride varnishes under acidic conditions.

Science.gov (United States)

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.

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

Science.gov (United States)

Shannon, I. L.

1975-01-01

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

Fluoride and sodium trimetaphosphate (TMP release from fluoride varnishes supplemented with TMP

Directory of Open Access Journals (Sweden)

Michele Mauricio MANARELLI

2016-01-01

Full Text Available Abstract This study assessed fluoride (F and sodium trimetaphosphate (TMP release into artificial saliva from varnishes containing 0%, 2.5%, and 5% NaF, supplemented or not with 5% TMP. The varnishes were applied on polyester sheets (n = 8/group, and F and TMP released into artificial saliva were measured for up to 24 hours. The amount of F and TMP released were directly related to NaF and TMP concentrations in the varnishes. The highest F release was seen for 5% NaF and 5% NaF + 5% TMP, whereas 5% TMP released the highest amount of TMP. However, the simultaneous addition of NaF and TMP to varnishes significantly reduced the amount of F and TMP released from the products.

A review of radiological hazards associated with tin by-product mineral processing industry in the SEATRAD centre member countries

International Nuclear Information System (INIS)

Udompornwirat, S.

1993-01-01

Radiological hazards associated with the tin by-product mineral processing industry has recently become an issue of concern in the SEATRAD Centre member countries namely, Indonesia, Malaysia and Thailand. The SEATRAD Centre, with the assistance of a United Nations Development Program consultant, carried out an investigation on radioactivity problems at twelve tin by-product mineral processing plants in Malaysia and Thailand. The investigation included a survey of external gamma radiation levels and dust sampling for internal dose estimation as well as characterising the potential sources of radiation exposure in the plants. This paper reviews the nature of the tin by-product mineral processing industry and the general levels of associated radiological hazards. In addition, data provided by the government organisations in the member countries are reviewed. Typical annual effective doses experienced by the industry's workers are estimated on the basis of existing information, and possible measures to reduce exposure are discussed. It is concluded that the estimated median effective dose experienced by the workers is about 18 to 19 mSv per annum. Maximum exposures may exceed 200 mSv per annum. The important exposure pathways are external gamma radiation and internal radiation arising through intake of radioactive dust. 5 refs., 2 tabs., 4 figs

Fluoridated Water

Science.gov (United States)

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

Self-propagating high-temperature synthesis of diamond-containing function-gradient materials with a ceramic matrix based on TiB2-TiN and Ti5Si3-TiN

International Nuclear Information System (INIS)

Levashov, E.A.; Akulinin, P.V.; Sorokin, M.N.; Sviridova, T.A.; Khosomi, S.; Okh'yanagi, M.; Koizumi, S.

2004-01-01

For the first time a study is made into specific features of phase- and structure formation in diamond-bearing functionally gradient materials (FGM) with a ceramic binder on the basis of titanium diboride and nitride TiB 2 -TiN as well as titanium silicide and nitride Ti 5 Si 3 -TiN. For a titanium diboride and nitride base binder the maximum residual strength of diamond grains is 24 N for a specimen with 12.5 vol. % of diamond and 29 N for a specimen with 25 vol. % of diamond in a charge layer when an initial strength of diamond grains is equal to 37 N. For a titanium silicide and nitride base binder the residual strength of diamond in synthesized products is 32.5 and 28.7 N for specimens with 12.5 and 25 vol. % of diamond respectively, the initial strength of diamond grains being the same. A positive effect is shown for a 5% additive of titanium hydride in a charge diamond-bearing layer on the preservation of diamond in a tita nium diboride and nitride binder. Optimal conditions are determined to provide the possibility of obtaining high-quality products with a high degree of preservation and strength of diamond grains [ru

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

Directory of Open Access Journals (Sweden)

Nahid Ramazani

2013-01-01

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

Profile of Fluoride Release from a Nanohybrid Composite Resin

Directory of Open Access Journals (Sweden)

Raquel Assed Bezerra Silva

2015-02-01

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

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

Science.gov (United States)

Lippert, Frank

2017-08-01

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

Fluoride salts and container materials for thermal energy storage applications in the temperature range 973 to 1400 K

Science.gov (United States)

Misra, Ajay K.; Whittenberger, J. Daniel

1987-01-01

Multicomponent fluoride salt mixtures were characterized for use as latent heat of fusion heat storage materials in advanced solar dynamic space power systems with operating temperatures in the range of 973 to 1400 K. The melting points and eutectic composition for many systems with published phase diagrams were verified, and several new eutectic compositions were identified. Additionally, the heats of fusion of several binary and ternary eutectics and congruently melting intermediate compounds were measured by differential scanning calorimetry. The extent of corrosion of various metals by fluoride melts was estimated from thermodynamic considerations, and equilibrium conditions inside a containment vessel were calculated as functions of the initial moisture content of the salt and free volume above the molten salt. Preliminary experimental data on the corrosion of commercial, high-temperature alloys in LiF-19.5CaF2 and NaF-27CaF2-36MgF2 melts are presented and compared to the thermodynamic predictions.

Radiolytic Effects on Fluoride Impurities in a U3O8 Matrix

International Nuclear Information System (INIS)

Icenhour, A.S.

2000-01-01

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

Effects of fluoridated milk on root dentin remineralization.

Directory of Open Access Journals (Sweden)

Wolfgang H Arnold

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

Nickel-Tin Electrode Materials for Nonaqueous Li-Ion Cells

Science.gov (United States)

Ehrlich, Grant M.; Durand, Christopher

2005-01-01

Experimental materials made from mixtures of nickel and tin powders have shown promise for use as the negative electrodes of rechargeable lithium-ion electrochemical power cells. During charging (or discharging) of a lithium-ion cell, lithium ions are absorbed into (or desorbed from, respectively) the negative electrode, typically through an intercalation or alloying process. The negative electrodes (for this purpose, designated as anodes) in state-of-the-art Li-ion cells are made of graphite, in which intercalation occurs. Alternatively, the anodes can be made from metals, in which alloying can occur. For reasons having to do with the electrochemical potential of intercalated lithium, metallic anode materials (especially materials containing tin) are regarded as safer than graphite ones; in addition, such metallic anode materials have been investigated in the hope of obtaining reversible charge/discharge capacities greater than those of graphite anodes. However, until now, each of the tin-containing metallic anode formulations tested has been found to be inadequate in some respect.

PREPARATION AND CHARACTERIZATION OF STRONTIUM FLUORIDE POWDERS ACTIVATED BY NEODYMIUM FLUORIDE

Directory of Open Access Journals (Sweden)

S. V. Kuznetsov

2015-07-01

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

Preparation of sup(99m)Tc-bleomycin with electrogenerated tin(II) ions

Energy Technology Data Exchange (ETDEWEB)

Pihlar, B; Marsel, J; Tasic, D [Ljubljana Univ. (Yugoslavia); Erjavec, M [Institute of Oncology, Ljubljana (Yugoslavia)

1978-01-01

Some parameters influencing the efficiency of labelling bleomycin (BLM) with sup(99m)Tc using tin electrodes for electrolytic production of tin(II) ions were investigated. The results showed clearly the superiority of tin electrodes for labelling BLM with sup(99m)Tc in comparison with Zn electrodes. The alteration of the primary properties of BLM is negligible. The optimal procedure for the labelling of BLM is as follows. Into a vessel (15-20 cm/sup 3/) containing the corresponding amount of BLM in saline, and the desired amount of sup(99m)TcO/sub 4//sup -/ eluate in 0.9% NaCl, 0.5 ml 0.5 M HCl is added and diluted with saline to 10 ml. The electrolysis is performed using tin electrodes with a current density of about 6 mA/cm/sup 2/ for 10 to 20 s with stirring, which is prolonged after electrolysis for a few minutes. After filtration through a 0.22 ..mu..m Millipore filter, the labelled compound can be used for clinical applications. For analytical control of labelled BLM, gel filtration on Sephadex G-25 with UV and radioactivity detection can be recommended. From the results obtained, it has been concluded that gel filtration on Sephadex G-25 can give applicable information about the quality of this radiopharmaceutical.

Evaluation of the suitability of tin slag in cementitious materials: Mechanical properties and Leaching behaviour

Science.gov (United States)

Rustandi, Andi; Wafa' Nawawi, Fuad; Pratesa, Yudha; Cahyadi, Agung

2018-01-01

Tin slag, a by-product of tin production has been used in cementitious application. The present investigation focuses on the suitability of tin slag as primary component in cement and as component that substitute some amount of Portland Cement. The tin slags studied were taken from Bangka, Indonesia. The main contents of the tin slag are SiO2, Al2O3, and Fe2O3 according to the XRF investigation. The aim of this article was to study the mechanical behaviour (compressive strength), microstructure and leaching behaviour of tin slag blended cement. This study used air-cooled tin slag that had been passed through 400# sieve to replace Portland Cement with ratio 0, 10, 20, 30, 40 by weight. Cement pastes and tin slag blended cement pastes were prepared by using water/cement ratio (W/C) of 0.40 by weight and hydrated for various curing ages of 3, 7, 14 days The microstructure of the raw tin slag was investigated using Scanning Electron Microscope (SEM). The phase composition of each cement paste was investigated using X-ray Diffraction (XRD). The aim of the leachability test was to investigate the environmental impacts of tin slag blended cement product in the range 4-8 pH by using static pH-dependent leaching test. The result show that the increase of the tin slag content decreasing the mortar compressive strength at early ages. The use of tin slag in cement provide economic benefits for all related industries.

Electrodeposition, characterization and corrosion behaviour of tin-20 wt.% zinc coatings electroplated from a non-cyanide alkaline bath

International Nuclear Information System (INIS)

Dubent, S.; Mertens, M.L.A.D.; Saurat, M.

2010-01-01

Tin-zinc alloy electroplated coatings are recognized as a potential alternative to toxic cadmium as corrosion resistant deposits because they combine the barrier protection of tin with the cathodic protection afforded by zinc. The coatings containing 20 wt.% zinc, balance tin, offer excellent corrosion protection for steel and do not form gross voluminous white corrosion products like pure zinc or high zinc alloy deposits. In this study, the effects of variables of the process (i.e. cathodic current density, pH and temperature) on deposit composition have been evaluated using a Hull cell to obtain 20 wt.% zinc alloy coatings. The tin-20 wt.% zinc deposits, produced with electroplating optimized conditions, were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), X-ray fluorescence spectrometry (XRF) and glow discharge optical emission spectrometry (GDOES). On the other hand, the corrosion behaviour of tin-zinc alloy electroplated coatings on steel has been investigated using electrochemical methods in a 3 wt.% NaCl solution and the salt spray test. The performance of the deposits was compared with cadmium and zinc-nickel electrodeposited coatings. The results show that the corrosion resistance of tin-20 wt.% zinc alloy coating is superior to that of cadmium and zinc-12 wt.% nickel coatings. Finally, sliding friction tests were conducted.

Xylitol-containing products for preventing dental caries in children and adults.

Science.gov (United States)

Riley, Philip; Moore, Deborah; Ahmed, Farooq; Sharif, Mohammad O; Worthington, Helen V

2015-03-26

to use a random-effects model in the event that there were four or more studies in a meta-analysis. We included 10 studies that analysed a total of 5903 participants. One study was assessed as being at low risk of bias, two were assessed as being at unclear risk of bias, with the remaining seven being at high risk of bias.The main finding of the review was that, over 2.5 to 3 years of use, a fluoride toothpaste containing 10% xylitol may reduce caries by 13% when compared to a fluoride-only toothpaste (PF -0.13, 95% CI -0.18 to -0.08, 4216 children analysed, low-quality evidence).The remaining evidence on children, from small single studies with risk of bias issues and great uncertainty associated with the effect estimates, was insufficient to determine a benefit from xylitol products. One study reported that xylitol syrup (8 g per day) reduced caries by 58% (95% CI 33% to 83%, 94 infants analysed, low quality evidence) when compared to a low-dose xylitol syrup (2.67 g per day) consumed for 1 year.The following results had 95% CIs that were compatible with both a reduction and an increase in caries associated with xylitol: xylitol lozenges versus no treatment in children (very low quality body of evidence); xylitol sucking tablets versus no treatment in infants (very low quality body of evidence); xylitol tablets versus control (sorbitol) tablets in infants (very low quality body of evidence); xylitol wipes versus control wipes in infants (low quality body of evidence).There was only one study investigating the effects of xylitol lozenges, when compared to control lozenges, in adults (low quality body of evidence). The effect estimate had a 95% CI that was compatible with both a reduction and an increase in caries associated with xylitol.Four studies reported that there were no adverse effects from any of the interventions. Two studies reported similar rates of adverse effects between study arms. The remaining studies either mentioned adverse effects but did not

Fluoride uptake from restorative dental materials by human enamel

International Nuclear Information System (INIS)

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

1976-01-01

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

Role of tin as a reducing agent in iron containing heat absorbing ...

Indian Academy of Sciences (India)

Unknown

infrared region and a narrow weak band for Fe3+ ion at its λmax at around 380 nm was observed in the silicate glass. ... Tin reducing agent; iron heat absorption; silicate glass. 1. ... ing point of aluminium metal is far below than the glass.

Anodic polarization of carbon graphite electrodes in chloride fluoride melts zirconium containing

International Nuclear Information System (INIS)

Lyapustin, A.A.; Kanashin, Yu.P.; Nichkov, I.F.; Smyshlyaev, V.Yu.

1985-01-01

Polarization of carbon graphite anodes in zircorium containing chloride fluoride melts of the KCl-K 2 ZrF 6 -KF composition at molar ratios [F]:[Zr] being equal to 6, 12, 18, 24, 30 has been studied. K 2 ZrF 6 concentration constitutes 25; 18.9; 15.2; 12.7; 11.8% (by mass), correspondingly. Vitreous carbon (VC-2500), high purity graphite and graphite EhG-0 have been used as anodic materials. Anodic polarization curves have been obtained under electrotype steady-state conditions at 973, 1023, 1073 K. Influence of concentration of fluorine ions in melt on polarization of carbon graphite anodes is shown. Content growth of fluorine ions in melt leads to shift of steady-state anode potentials to their negative values regardless a graphite mark. The most con siderable potential shift on 0.5 V takes plase at molar ratio [F]:[Zr] increasing from 6 to 12. Temperature increase, as measurements showed, doesn't influence greatly on polarization curve shape

DISSOLUTION OF LANTHANUM FLUORIDE PRECIPITATES

Science.gov (United States)

Fries, B.A.

1959-11-10

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

Preparation of bromine fluoride

International Nuclear Information System (INIS)

Domange, Pr; Duflo, J.

1958-05-01

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

Fluoride reactions with dental enamel following different forms of fluoride supply

International Nuclear Information System (INIS)

Hellstroem, I.; Ericsson, Y.

1976-01-01

The reactions with dental enamel of NaF as tablets dissolved in different beverages or supplied with NaCl, simulating domestic salt fluoridation, were studied in tests with enamel surfaces and enamel powder. It was confirmed that powdered enamel can react quite differently from enamel surfaces under certain conditions. Enamel surfaces took up much more fluoride (F) from orange juice than from water or milk, and neither the low pH nor the citrate content of the juice increased the formation of unstable CaF 2 in the enamel, as judged from a KOH leaching test. The F uptake by enamel surfaces from 0.25 mM NaF in 175 mM NaCl, corresponding to a dish prepared with salt containing 500 parts/10 6 F, was about 80 percent greater than from the same NaF concentration in water. This NaCl concentration did not increase the formation of CaF 2 in the enamel, as judged from the KOH test, while 350 mM NaCl caused a moderate increase. The investigations support the administration of NaF tablets with orange juice and the plans for domestic salt fluoridation. (author)

Electrical and Optical Properties of Fluorine Doped Tin Oxide Thin Films Prepared by Magnetron Sputtering

Directory of Open Access Journals (Sweden)

Ziad Y. Banyamin

2014-10-01

Full Text Available Fluorine doped tin oxide (FTO coatings have been prepared using the mid-frequency pulsed DC closed field unbalanced magnetron sputtering technique in an Ar/O2 atmosphere using blends of tin oxide and tin fluoride powder formed into targets. FTO coatings were deposited with a thickness of 400 nm on glass substrates. No post-deposition annealing treatments were carried out. The effects of the chemical composition on the structural (phase, grain size, optical (transmission, optical band-gap and electrical (resistivity, charge carrier, mobility properties of the thin films were investigated. Depositing FTO by magnetron sputtering is an environmentally friendly technique and the use of loosely packed blended powder targets gives an efficient means of screening candidate compositions, which also provides a low cost operation. The best film characteristics were achieved using a mass ratio of 12% SnF2 to 88% SnO2 in the target. The thin film produced was polycrystalline with a tetragonal crystal structure. The optimized conditions resulted in a thin film with average visible transmittance of 83% and optical band-gap of 3.80 eV, resistivity of 6.71 × 10−3 Ω·cm, a carrier concentration (Nd of 1.46 × 1020 cm−3 and a mobility of 15 cm2/Vs.

An Investigation of Fluoride Concentration in Drinking Water of Sanganer Tehsil, Jaipur District, Rajasthan, India and Defluoridation from Plant Material

Directory of Open Access Journals (Sweden)

Mohammed Arif

2014-01-01

Full Text Available Forty water samples of 20 villages of Sanganer tehsil, Jaipur district were analyzed for determining fluoride ion concentrations. High fluoride containing regions were identified on the basis of fluoride levels of the water samples and also on the prevalence rate of dental and skeletal fluorosis of the study area. Fluoride maps, which distinguish the regions containing the water sources of different ranges of fluoride ion concentrations, were also prepared by isopleth’s technique, a statistical method. Water samples containing high fluoride levels were defluoridated with low-cost materials prepared from plant byproducts. These materials successfully decrease the fluoride ions concentration to an acceptable limit (from 0.5 to 1.5 mg/L without disturbing drinking water quality standards.

Studies on Cementation of Tin on Copper and Tin Stripping from Copper Substrate

Directory of Open Access Journals (Sweden)

Rudnik E.

2016-06-01

Full Text Available Cementation of tin on copper in acid chloride-thiourea solutions leads to the formation of porous layers with a thickness dependent on the immersion time. The process occurs via Sn(II-Cu(I mechanism. Chemical stripping of tin was carried out in alkaline and acid solutions in the presence of oxidizing agents. It resulted in the dissolution of metallic tin, but refractory Cu3Sn phase remained on the copper surface. Electrochemical tin stripping allows complete tin removal from the copper substrate, but porosity and complex phase composition of the tin coating do not allow monitoring the process in unambiguous way.

TIN-X

DEFF Research Database (Denmark)

Cannon, Daniel C; Yang, Jeremy J; Mathias, Stephen L

2017-01-01

between proteins and diseases, based on text mining data processed from scientific literature. In the current implementation, TIN-X supports exploration of data for G-protein coupled receptors, kinases, ion channels, and nuclear receptors. TIN-X supports browsing and navigating across proteins......Motivation: The increasing amount of peer-reviewed manuscripts requires the development of specific mining tools to facilitate the visual exploration of evidence linking diseases and proteins. Results: We developed TIN-X, the Target Importance and Novelty eXplorer, to visualize the association...

Preparation of high quality spray-deposited fluorine-doped tin oxide thin films using dilute di(n-butyl)tin(iv) diacetate precursor solutions

Energy Technology Data Exchange (ETDEWEB)

Premalal, E.V.A., E-mail: vikum777@gmail.com [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu (Japan); Dematage, N. [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu (Japan); Kaneko, S. [SPD Laboratory Inc, Hi-Cube 3-1-7, Wajiyama, Naka-ku, Hamamatsu (Japan); Konno, A. [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu (Japan)

2012-09-01

Fluorine-doped tin oxide (FTO) thin films were prepared, at different substrate temperatures, using dilute precursor solutions of di(n-butyl)tin(iv) diacetate (0.1 M DBTDA) by varying the F{sup -} concentration in the solution. It is noticed that conductivity of FTO film is increasing by increasing the fluorine amount in the solution. Morphology of SEM image reveals that grain size and its distribution are totally affected by the substrate temperature in which conductivity is altered. Among these FTO films, the best film obtained gives an electronic conductivity of 31.85 Multiplication-Sign 10{sup 2} {Omega}{sup -1} cm{sup -1}, sheet resistance of 4.4 {Omega}/{open_square} ({rho} = 3.14 Multiplication-Sign 10{sup -4} {Omega} cm) with over 80% average normal transmittance between the 400 and 800 nm wavelength range. The best FTO film consists of a large distribution of grain sizes from 50 nm to 400 nm range and the optimum conditions used are 0.1 M DBTDA, 0.3 M ammonium fluoride, in a mixture of propan-2-ol and water, at 470 Degree-Sign C substrate temperature. The large distribution of grain sizes can be easily obtained using low DBTDA concentration ({approx} 0.1 M or less) and moderate substrate temperature (470 Degree-Sign C). - Highlights: Black-Right-Pointing-Pointer F-doped SnO{sub 2} (FTO) thin films prepared using di(n-butyl)tin(iv) diacetate (DBTDA). Black-Right-Pointing-Pointer Substrate temperature and DBTDA concentration affect grain size and distribution. Black-Right-Pointing-Pointer Large distribution of grain sizes can optimize the conductivity of FTO film. Black-Right-Pointing-Pointer 0.1 M DBTDA, substrate temperature of 470 Degree-Sign C allows a large grain size distribution.

Organic derivatives of tin (II/IV): Investigation of their structure

Energy Technology Data Exchange (ETDEWEB)

Szirtes, L., E-mail: szirtes@iki.kfki.h [Institute of Isotopes of the Hungarian Academy of Sciences, Budapest H-1525, P.O. Box 77 (Hungary); Megyeri, J., E-mail: megyeri@iki.kfki.h [Institute of Isotopes of the Hungarian Academy of Sciences, Budapest H-1525, P.O. Box 77 (Hungary); Kuzmann, E. [Laboratory of Nuclear Chemistry, CRC of the Hungarian Academy of Science at Eoetvoes University, H-1518 Budapest, P.O. Box 32 (Hungary); Beck, A. [Institute of Isotopes of the Hungarian Academy of Sciences, Budapest H-1525, P.O. Box 77 (Hungary)

2011-07-15

The structures of tin(II)-oxalate, tin(IV)Na-EDTA and tin(IV)Na{sub 8}-inositol hexaphosphate were investigated using XRD analysis. Samples were identified using the Moessbauer study, thermal analysis and FTIR spectrometry. The Moessbauer study determined two different oxidation states of tin atoms, and consequently two different tin surroundings in the end products. The tin oxalate was found to be orthorhombic with space group Pnma, a=9.2066(3) A, b=9.7590(1) A, c=13.1848(5) A, V=1184.62 A{sup 3} and Z=8. SnNa-EDTA was found to be monoclinic with space group P2{sub 1}/c{sub 1}, a=10.7544(3) A, b=10.1455(3) A, c=16.5130(6) A, {beta}=98.59(2){sup o}, V=1781.50(4) A{sup 3} and Z=4. Sn(C{sub 6}H{sub 6}Na{sub 8}O{sub 24}P{sub 6}) was found to be amorphous.

Antibacterial Properties of Calcium Fluoride-Based Composite Materials: In Vitro Study

Science.gov (United States)

Zarzycka, Beata; Grzegorczyk, Janina; Sokołowski, Krzysztof; Półtorak, Konrad; Sokołowski, Jerzy

2016-01-01

The aim of the study was to evaluate antibacterial activity of composite materials modified with calcium fluoride against cariogenic bacteria S. mutans and L. acidophilus. One commercially available conventional light-curing composite material containing fluoride ions (F2) and two commercially available flowable light-curing composite materials (Flow Art and X-Flow) modified with 1.5, 2.5, and 5.0 wt% anhydrous calcium fluoride addition were used in the study. Composite material samples were incubated in 0.95% NaCl at 35°C for 3 days; then dilution series of S. mutans and L. acidophilus strains were made from the eluates. Bacteria dilutions were cultivated on media afterwards. Colony-forming unit per 1 mL of solution (CFU/mL) was calculated. Composite materials modified with calcium fluoride highly reduced (p composite materials containing fluoride compounds. The greatest reduction in bacteria growth was observed for composite materials modified with 1.5% wt. CaF2. All three tested composite materials showed statistically greater antibacterial activity against L. acidophilus than against S. mutans. PMID:28053976

Solubility and fluoride release in ionomers and compomers.

Science.gov (United States)

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

1999-03-01

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

Urinary fluoride as a monitoring tool for assessing successful intervention in the provision of safe drinking water supply in five fluoride-affected villages in Dhar district, Madhya Pradesh, India.

Science.gov (United States)

Srikanth, R; Gautam, Anil; Jaiswal, Suresh Chandra; Singh, Pavitra

2013-03-01

Endemic fluorosis was detected in 31 villages in the Dhar district of Madhya Pradesh, Central India. Out of the 109 drinking water sources that were analyzed, about 67 % were found to contain high concentration of fluoride above the permissible level of 1.0 mg/l. Dental fluorosis among the primary school children in the age between 8 and 15 served as primary indicator for fluoride intoxication among the children. Urinary fluoride levels among the adults were found to be correlated with drinking water fluoride in 10 villages affected by fluoride. Intervention in the form of alternate safe water supply in five villages showed significant reduction in the urinary fluoride concentration when compared to the control village. Urinary fluoride serves as an excellent marker for assessing the effectiveness of intervention program in the fluoride-affected villages.

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

OpenAIRE

Giti Javan; Ehsan Mostaghni; Seyed Mojtaba Jafary; Batoul Amini; Bahram Hematinejad

2006-01-01

Background: Fluoride increases tooth resistance to dental caries, but mild toxicity due to excessive ingestion of fluoride can cause dental fluorosis. Drinking water naturally contains fluoride and is a major source of fluoride. In Bushehr port, drinking water is supplied from limestone springs with normal fluoride levels but dental fluorosis is observed. Methods: A total of 95 native school children (between the ages of 10-12 years old) were randomly selected from four Bushehr port regions. ...

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

Science.gov (United States)

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

2016-01-01

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

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

Science.gov (United States)

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

2004-03-01

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

A Review on Adsorption of Fluoride from Aqueous Solution

Science.gov (United States)

Habuda-Stanić, Mirna; Ergović Ravančić, Maja; Flanagan, Andrew

2014-01-01

Fluoride is one of the anionic contaminants which is found in excess in surface or groundwater because of geochemical reactions or anthropogenic activities such as the disposal of industrial wastewaters. Among various methods used for defluoridation of water such as coagulation, precipitation, membrane processes, electrolytic treatment, ion-exchange, the adsorption process is widely used. It offers satisfactory results and seems to be a more attractive method for the removal of fluoride in terms of cost, simplicity of design and operation. Various conventional and non-conventional adsorbents have been assessed for the removal of fluoride from water. In this review, a list of various adsorbents (oxides and hydroxides, biosorbents, geomaterials, carbonaceous materials and industrial products and by-products) and its modifications from literature are surveyed and their adsorption capacities under various conditions are compared. The effect of other impurities on fluoride removal has also been discussed. This survey showed that various adsorbents, especially binary and trimetal oxides and hydroxides, have good potential for the fluoride removal from aquatic environments. PMID:28788194

The tin mining and heavy mineral processing industry in the Kinta Valley, Perak, Malaysia

International Nuclear Information System (INIS)

Lee Swee Ching

1994-01-01

Overview of the tin mining and heavy mineral processing in the Kinta Valley, Perak, Malaysia was presented. Amang, a mixture composed of tin ore, sand, ilmenite, monazite, zircon, xenotime, struvite, etc , as a product from tin mining activities was discussed too in this paper

Artificial caries formation around fluoride-releasing restorations in roots.

Science.gov (United States)

Dionysopoulos, P; Kotsanos, N; Papadogiannis, Y; Konstantinidis, A

1998-11-01

Secondary caries is one of the most important factors leading to replacement of dental restorations. This investigation assessed the capacity of fluoride-releasing restorative materials to resist caries in vitro when used in roots. Class 5 cavities were prepared in the buccal and lingual surfaces of 30 extracted premolars. The six materials used were: glass-ionomer cement (Fuji), glass-ionomer cement with silver particles added (Ketac-silver), fluoride-containing composite resin (Tetric), composite resin (Silux plus), fluoride-containing amalgam (Fluor-Alloy) and high-copper amalgam (Dispersalloy). After 5 weeks in an acid gel for caries-like lesion formation, the teeth were sectioned longitudinally and examined with polarized light. The results showed that repair with glass-ionomer materials of a carious lesion may be of great importance in the prevention of secondary caries around the restorations in roots.

Protection From Dental Erosion: All Fluorides are Not Equal.

Science.gov (United States)

Faller, Robert V; Noble, Warden H

2018-03-01

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

Sources of fluoride pollution in Kasur district, Pakistan

International Nuclear Information System (INIS)

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

2005-01-01

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

On the electrochemistry of tin oxide coated tin electrodes in lithium-ion batteries

International Nuclear Information System (INIS)

Böhme, Solveig; Edström, Kristina; Nyholm, Leif

2015-01-01

As tin based electrodes are of significant interest in the development of improved lithium-ion batteries it is important to understand the associated electrochemical reactions. In this work it is shown that the electrochemical behavior of SnO_2 coated tin electrodes can be described based on the SnO_2 and SnO conversion reactions, the lithium tin alloy formation and the oxidation of tin generating SnF_2. The CV, XPS and SEM data, obtained for electrodeposited tin crystals on gold substrates, demonstrates that the capacity loss often observed for SnO_2 is caused by the reformed SnO_2 layer serving as a passivating layer protecting the remaining tin. Capacities corresponding up to about 80 % of the initial SnO_2 capacity could, however, be obtained by cycling to 3.5 V vs. Li"+/Li. It is also shown that the oxidation of the lithium tin alloy is hindered by the rate of the diffusion of lithium through a layer of tin with increasing thickness and that the irreversible oxidation of tin to SnF_2 at potentials larger than 2.8 V vs. Li"+/Li is due to the fact that SnF_2 is formed below the SnO_2 layer. This improved electrochemical understanding of the SnO_2/Sn system should be valuable in the development of tin based electrodes for lithium-ion batteries.

Colorimetric visualization of tin corrosion: A method for early stage corrosion detection on printed circuit boards

DEFF Research Database (Denmark)

Verdingovas, Vadimas; Jellesen, Morten Stendahl; Ambat, Rajan

2017-01-01

A majority of printed circuit board surfaces are covered with tin, therefore tin corrosion under humid conditions and movement of tin ions under the influence of an electric field plays an important role in the corrosion failure development. Tracking tin corrosion products spread on the printed c...

Separation of substandard tin ores by x-ray fluorescence method

International Nuclear Information System (INIS)

Kotler, N.I.; Konovalov, V.M.; Kamenskij, Yu.V.; Neverov, A.D.; Ogorodnikov, Yu.V.

1987-01-01

Analysis of pure tin ores on X-ray fluorescence separation (XFS) is carried out. The volumes of lump sampling are substantiated; several variants of technical and economical efficiency of XFS application have been calculated. It is shown that at XFS of -400+25 mm classes conditional as to tin content intermediate product with high efficiency factor may be prepared. Separation of -25+10 mm class is unsuitable, as it doesn't allow to increase tin content to conditional, and the process efficiency is low

Determination of tin, chromium, cadmium and lead in canned fruits from the Czech market

Directory of Open Access Journals (Sweden)

Pavel Diviš

2017-01-01

Full Text Available The global production of metal cans is more than 300 billion cans. Benefits of metal packaging consist mainly from the great strenght, excellent barrier properties and good thermal conductivity. The main problem of used metal packaging are the corrosion processes. The corrosion of metal container causes dissolution of tin which is used as a protective layer of the steel shell of the can and other metallic elements used in the manufacture of cans. In this work 31 samples of canned fruit was analysed and the concentration of tin, chromium, cadmium and lead was determined in fruit and in syrup using ICP-OES and ICP-MS techniques. The results showed no difference between the concentration of analysed elements in fruit and in syrup. In none of the analyzed samples the permitted maximum concentration of tin 200 mg.kg-1 was exceeded. Maximum concentration of tin was measured in canned grepfruit (59.8 ±1.9 mg.kg-1. The age of cans had no significant effect on the concentration of tin in canned fruit. The concentration of tin in fruit packaged in cans with protective layer of lacquer was significantly lower than the concentration of tin in fruit packaged in cans without protective layer of lacquer. Concentration of chromium, cadmium and lead in the analysed samples was very low at the natural levels of occurrence of these metals in fruit and it was impossible to determine unequivocally that the measured concentrations of these metals in canned fruit originate from the corrosion of can. The corrosion of the tinplate was studied using scanning electron microscopy with an energy dispersive spectrometer. By analyzing the SEM pictures and EDS spectra, critical areas of tin plate corrosion were observed. Based on the measured results it can be concluded that the consumption of fresh canned fruit is not a major problem for the inhabitants of the Czech Republic in terms of intake of potentially hazardous metals.

Reduction of Erosive Wear in situ by Stannous Fluoride-Containing Toothpaste.

NARCIS (Netherlands)

Huysmans, M.C.D.N.J.M.; Jager, D.H.; Ruben, J.L.; Unk, D.E.; Klijn, C.P.; Vieira, A.M.

2011-01-01

Background/Aims: Stannous fluoride (SnF) has been suggested as a dental erosion-preventive agent. The aim of this single-centre, randomized, double-blind, in situ study was to evaluate the effect of toothpastes with SnF in the prevention of erosive enamel wear. Methods: A combined split-mouth

Low-debris, efficient laser-produced plasma extreme ultraviolet source by use of a regenerative liquid microjet target containing tin dioxide (SnO2) nanoparticles

Science.gov (United States)

Higashiguchi, Takeshi; Dojyo, Naoto; Hamada, Masaya; Sasaki, Wataru; Kubodera, Shoichi

2006-05-01

We demonstrated a low-debris, efficient laser-produced plasma extreme ultraviolet (EUV) source by use of a regenerative liquid microjet target containing tin-dioxide (SnO2) nanoparticles. By using a low SnO2 concentration (6%) solution and dual laser pulses for the plasma control, we observed the EUV conversion efficiency of 1.2% with undetectable debris.

Low-debris, efficient laser-produced plasma extreme ultraviolet source by use of a regenerative liquid microjet target containing tin dioxide (SnO2) nanoparticles

International Nuclear Information System (INIS)

Higashiguchi, Takeshi; Dojyo, Naoto; Hamada, Masaya; Sasaki, Wataru; Kubodera, Shoichi

2006-01-01

We demonstrated a low-debris, efficient laser-produced plasma extreme ultraviolet (EUV) source by use of a regenerative liquid microjet target containing tin-dioxide (SnO 2 ) nanoparticles. By using a low SnO 2 concentration (6%) solution and dual laser pulses for the plasma control, we observed the EUV conversion efficiency of 1.2% with undetectable debris

Catalytic versatility of Bacillus pumilus β-xylosidase: glycosyl transfer and hydrolysis promoted with α- and β-D-xylosyl fluoride

International Nuclear Information System (INIS)

Kasumi, T.; Tsumuraya, Y.; Brewer, C.F.; Kersters-Hilderson, H.; Claeyssens, M.; Hehre, E.J.

1987-01-01

Bacillus pumilus β-xylosidase, an enzyme considered restricted to hydrolyzing a narrow range of β-D-xylosidic substrates with inversion of configuration, was found to catalyze different stereochemical, essentially irreversible, glycosylation reactions with α- and β-D-xylopyranosyl fluoride. The enzyme promoted the hydrolysis of β-D-xylopyranosyl fluoride at a high rate, V = 6.25 μmol min -1 mg -1 at 0 0 C, in a reaction that obeyed Michaelis-Menten kinetics. In contrast, its action upon α-D-xylopyranosyl fluoride was slow and characterized by an unusual relation between the rate of fluoride release and the substrate concentration, suggesting the possible need for two substrate molecules to be bound at the active center in order for reaction to occur. Moreover, 1 H NMR spectra of a digest of α-D-xylosyl fluoride showed the substrate to be specifically converted to α-D-xylose by the enzyme. The observed retention of configuration is not consistent with direct hydrolysis by this inverting enzyme but is strongly indicative of the occurrence of two successive inverting reactions: xylosyl transfer from α-D-xylosyl fluoride to form a β-D-xylosidic product, followed by hydrolysis of the latter to produce α-D-xylose. The transient intermediate product formed enzymically from α-D-xylosyl fluoride in the presence of [ 14 C]xylose was isolated and shown by its specific radioactivity and 1 H NMR spectrum as well as by methylatino and enzymic analyses to be 4-O-β-D-xylopyranosyl-D-xylopyranose containing one [ 14 C]xylose residue

Moessbauer Studies of Stannous Fluoride Reactivity with Synthetic Tooth Enamel - A Model for the Tooth Cavity Protection Actions of Novel Dentifrices

International Nuclear Information System (INIS)

Denes, Georges; Muntasar, Abdualhafeed; Kozak, Kathy M.; Baig, Arif A.; White, Donald J.

2002-01-01

SnF 2 is an important toothpaste ingredient, added for the provision of clinical efficacy for hard and soft tissue diseases and in breath protection. Synthetic calcium hydroxyapatite powders were exposed to liquid supernates (25 w/w% toothpaste water slurries, centrifuged) of Crest Gum Care (registered) (SnF 2 ) dentifrice. One-minute treatments were followed by 3x water washing, centrifugation and lyophilization. Post treatment, powders were analyzed by Moessbauer spectroscopy with 0.5-1 gram of treated apatite powder. Results show that tooth mineral stannous fluoride interactions include: (1) formation of surface reaction products with both Sn(II) and Sn(IV) oxidation states; (2) Sn-F binding on mineral surfaces with no evidence of SnO. The surface binding is, however, not pure Sn-F but contains contributions of other ligands, probably oxygens from surface phosphates or hydroxyl groups. Results also suggest that surface reacted stannous tin is oxidized with time, even when bound as a layer on the tooth surface. This study demonstrates for the first time the presence of Sn-F on tooth enamel post treatment and the contribution of passivation to long term stannous chemistry on tooth surfaces. The study also illustrates the practical applications of the Moessbauer technique.

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

Energy Technology Data Exchange (ETDEWEB)

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.

Contribution to the study of transport and diffusion properties inside fluoride glasses based on zirconium tetrafluoride

International Nuclear Information System (INIS)

Bobe, Jean-Marc

1995-01-01

This research thesis addresses the study of electric and diffusion properties of fluoride and fluorine-oxide glasses based on zirconium tetrafluoride, and more specifically in the case either of glasses free of alkaline fluoride, or of glasses containing lithium fluoride or sodium fluoride. Some techniques have been systematically used for this purpose: impedance spectroscopy, and NMR of Fluorine 19, lithium 7 or sodium 23 atoms. The objectives were to determine: 1) the presence or absence of different sites for fluorine ions and, should the occasion occurs, the distribution of these ions among the different sites; 2) the nature and number of mobile ions within these materials; 3) the role played by alkaline ions in these materials. After a presentation of experimental techniques, the author reports the comparative study of electric and diffusion properties of some sets of fluorinated glasses free of alkaline fluoride, and, for comparative purposes, of some crystallized phases having a similar composition. Two chapters respectively address the study of fluorinated glasses containing sodium fluoride and of fluorinated glasses containing sodium fluoride. Then, by applying the Almond-West model to some glasses containing NaF, conductivity parameters (number of carriers, mobility, entropic factor, and so on) have been assessed for a wide range of temperatures and frequencies. Movements of F ions determined by impedance spectroscopy are compared with those obtained by NMR. [fr

Biomonitoring Equivalents for interpretation of urinary fluoride.

Science.gov (United States)

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

2015-06-01

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

Preparation and study of chlorine mono-fluoride and of chlorine oxi-fluorides; Preparation et etude du monofluorure et des oxyfluorures de chlore

Energy Technology Data Exchange (ETDEWEB)

Macheteau, Yves

1969-07-01

The objective of this engineering school report was to be a contribution to the study of a family of fluorine compounds: chlorine mono-fluoride (ClF), chlorine fluoride oxide (ClOF), chloryl fluoride (ClO{sub 2}F), perchloryl fluoride (ClO{sub 3}F) and perchloryl oxi-fluoride (ClO{sub 4}F). Such a study required very pure products to be obtained in order to be able to characterize them by different methods (infrared, micro-sublimation, and chromatography). The thermolysis of ClO{sub 2}F and ClO{sub 4}F has been particularly studied, and magnetic resonance has been used to establish a relationship between fluorine chemical displacement and the electro-negativity of the F-X bond where X represents the atom group to which fluorine is bonded.

FLUORIDE: A REVIEW OF USE AND EFFECTS ON HEALTH.

Science.gov (United States)

Kanduti, Domen; Sterbenk, Petra; Artnik, Barbara

2016-04-01

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

Fluoride Consumption and Its Impact on Oral Health

Directory of Open Access Journals (Sweden)

Luis Fernando Jacinto-Alemán

2011-01-01

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

Emissions of fluorides from welding processes.

Science.gov (United States)

Szewczyńska, Małgorzata; Pągowska, Emilia; Pyrzyńska, Krystyna

2015-11-01

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

Fluoride

Science.gov (United States)

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

Analysis of Phone Calls Regarding Fluoride Exposure made to New Jersey Poison Control Center from 2010 to 2012.

Science.gov (United States)

Shah, Sneha; Quek, Samuel; Ruck, Bruce

2016-02-01

,671). Based on the data, there were no reports of lethality or toxicity due to acute fluoride exposure in New Jersey from 2010 through 2012. Symptomatic reports and informational inquiries were few. All adverse outcomes due to excessive fluoride intake were remedied with calcium as the antidote. Dental hygienists should educate patients on safety measures of fluoride-containing products and evaluate overall fluoride exposure prior to making recommendations. However, findings in this study suggest that levels of fluoride in available commercial products will not produce life-threatening events, even if taken in doses higher than recommended. Copyright © 2016 The American Dental Hygienists’ Association.

PRODUCTION OF TRITIUM

Science.gov (United States)

Jenks, G.H.; Shapiro, E.M.; Elliott, N.; Cannon, C.V.

1963-02-26

This invention relates to a process for the production of tritium by subjecting comminuted solid lithium fluoride containing the lithium isotope of atomic mass number 6 to neutron radiation in a self-sustaining neutronic reactor. The lithium fiuoride is heated to above 450 deg C. in an evacuated vacuum-tight container during radiation. Gaseous radiation products are withdrawn and passed through a palladium barrier to recover tritium. (AEC)

Fluoride content and labelling of toothpastes marketed in India.

Science.gov (United States)

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

2015-09-01

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

Production of multifilamentary Nb3Sn composites incorporating a high tin bronze

International Nuclear Information System (INIS)

Petrovich, A.; Zeithlin, B.A.; Walker, M.S.

1977-01-01

The economics and processing methods have been examined for the fabrication of multifilamentary Nb 3 Sn using a high tin bronze reactive matrix. Four conductor configurations utilizing the high tin bronze were compared with a conventional Cu-13 wt % Sn bronze. The most promising of these designs is potentially 40% lower in cost per ampere meter than the conventional composite. Large hydrostatic extrusion facilities, which are required for the high tin processing, are not presently available in this country but can be made by conversion of conventional presses. They exist in Europe. Experiments were conducted to investigate the applicability of hydrostatic extrusion, and billet components were successfully prepared using the hydrostatic extrusion technique. We have concluded that the economics, availability of facilities and initial fabrication results are favorable for this type of conductor and that the next stage in this program of scale up to extrusion and drawing of 2'' to 3'' diameter composite billets should be undertaken

Coupling NMR with Synchrotron radiation at high temperature for the study of molten fluorides : applied to zirconium fluorides

International Nuclear Information System (INIS)

Maksoud, Louis

2013-01-01

Molten fluorides are used in Molten Salt Reactors MSR such as the non moderated fast reactor MSFR, where the molten salt LiF-ThF 4 is the fuel and the coolant. The formation of fission products (FP) such as lanthanides, during the reactor operation, possibly modifies the physicochemical properties of the melt. It is therefore important to characterize the melt from the structural and the dynamics point of view in order to determine its properties. Because of problems related to the radioactivity of thorium, as well as requirements related to spectroscopic methods, the system studied in this thesis is the LiF-ZrF 4 -LaF 3 (zirconium and lanthanum are possible FP). The approach followed in this thesis combines measurements by NMR spectroscopy and EXAFS at 850 C with molecular dynamics simulations. In the molten salt, we have shown the existence of zirconium and lanthanum complexes with different coordination numbers, whose proportions depend on the composition. Depending on the content of ZrF 4 , [ZrF 7 ] 3- species are dominant but change slightly and are further connected between each other's via bridging fluorine. The addition of LaF 3 to the mixture stabilizes the 7 coordination number around the zirconium and tends to enrich the environment of lanthanum with fluorides. A medium-range order is established between the various complexes containing zirconium and lanthanum due to bridging fluorine. Species dynamics is slower when the amount of either ZrF 4 or LaF 3 is higher. We noted a significant effect on the structure and dynamics of species starting 10 mol% LaF 3 added to the medium. The data obtained by this novel approach concerning the chemistry of the molten salt in MSR containing FP, are fundamental to improve the separation of these products and optimize the process. (author)

Inductively coupled plasma atomic emission spectrometric determination of tin in canned food.

Science.gov (United States)

Sumitani, H; Suekane, S; Nakatani, A; Tatsuka, K

1993-01-01

Various canned foods were digested sequentially with HNO3 and HCl, diluted to 100 mL, and filtered, and then tin was determined by inductively coupled plasma atomic emission spectrometry (ICP/AES). Samples of canned Satsuma mandarin, peach, apricot, pineapple, apple juice, mushroom, asparagus, evaporated milk, short-necked clam, spinach, whole tomato, meat, and salmon were evaluated. Sample preparations did not require time-consuming dilutions, because ICP/AES has wide dynamic range. The standard addition method was used to determine tin concentration. Accuracy of the method was tested by analyzing analytical standards containing tin at 2 levels (50 and 250 micrograms/g). The amounts of tin found for the 50 and 250 micrograms/g levels were 50.5 and 256 micrograms/g, respectively, and the repeatability coefficients of variation were 4.0 and 3.8%, respectively. Recovery of tin from 13 canned foods spiked at 2 levels (50 and 250 micrograms/g) ranged from 93.9 to 109.4%, with a mean of 99.2%. The quantitation limit for tin standard solution was about 0.5 microgram/g.

4-phenylbutyrate Mitigates Fluoride-Induced Cytotoxicity in ALC Cells

Directory of Open Access Journals (Sweden)

Maiko Suzuki

2017-05-01

Full Text Available Chronic fluoride over-exposure during pre-eruptive enamel development can cause dental fluorosis. Severe dental fluorosis is characterized by porous, soft enamel that is vulnerable to erosion and decay. The prevalence of dental fluorosis among the population in the USA, India and China is increasing. Other than avoiding excessive intake, treatments to prevent dental fluorosis remain unknown. We previously reported that high-dose fluoride induces endoplasmic reticulum (ER stress and oxidative stress in ameloblasts. Cell stress induces gene repression, mitochondrial damage and apoptosis. An aromatic fatty acid, 4-phenylbutyrate (4PBA is a chemical chaperone that interacts with misfolded proteins to prevent ER stress. We hypothesized that 4PBA ameliorates fluoride-induced ER stress in ameloblasts. To determine whether 4PBA protects ameloblasts from fluoride toxicity, we analyzed gene expression of Tgf-β1, Bcl2/Bax ratio and cytochrome-c release in vitro. In vivo, we measured fluorosis levels, enamel hardness and fluoride concentration. Fluoride treated Ameloblast-lineage cells (ALC had decreased Tgf-β1 expression and this was reversed by 4PBA treatment. The anti-apoptotic Blc2/Bax ratio was significantly increased in ALC cells treated with fluoride/4PBA compared to fluoride treatment alone. Fluoride treatment induced cytochrome-c release from mitochondria into the cytosol and this was inhibited by 4PBA treatment. These results suggest that 4PBA mitigates fluoride-induced gene suppression, apoptosis and mitochondrial damage in vitro. In vivo, C57BL/6J mice were provided fluoridated water for six weeks with either fluoride free control-chow or 4PBA-containing chow (7 g/kg 4PBA. With few exceptions, enamel microhardness, fluorosis levels, and fluoride concentrations of bone and urine did not differ significantly between fluoride treated animals fed with control-chow or 4PBA-chow. Although 4PBA mitigated high-dose fluoride toxicity in vitro, a diet

4-phenylbutyrate Mitigates Fluoride-Induced Cytotoxicity in ALC Cells.

Science.gov (United States)

Suzuki, Maiko; Everett, Eric T; Whitford, Gary M; Bartlett, John D

2017-01-01

Chronic fluoride over-exposure during pre-eruptive enamel development can cause dental fluorosis. Severe dental fluorosis is characterized by porous, soft enamel that is vulnerable to erosion and decay. The prevalence of dental fluorosis among the population in the USA, India and China is increasing. Other than avoiding excessive intake, treatments to prevent dental fluorosis remain unknown. We previously reported that high-dose fluoride induces endoplasmic reticulum (ER) stress and oxidative stress in ameloblasts. Cell stress induces gene repression, mitochondrial damage and apoptosis. An aromatic fatty acid, 4-phenylbutyrate (4PBA) is a chemical chaperone that interacts with misfolded proteins to prevent ER stress. We hypothesized that 4PBA ameliorates fluoride-induced ER stress in ameloblasts. To determine whether 4PBA protects ameloblasts from fluoride toxicity, we analyzed gene expression of Tgf -β 1, Bcl2 / Bax ratio and cytochrome-c release in vitro . In vivo , we measured fluorosis levels, enamel hardness and fluoride concentration. Fluoride treated Ameloblast-lineage cells (ALC) had decreased Tgf -β 1 expression and this was reversed by 4PBA treatment. The anti-apoptotic Blc2 / Bax ratio was significantly increased in ALC cells treated with fluoride/4PBA compared to fluoride treatment alone. Fluoride treatment induced cytochrome-c release from mitochondria into the cytosol and this was inhibited by 4PBA treatment. These results suggest that 4PBA mitigates fluoride-induced gene suppression, apoptosis and mitochondrial damage in vitro . In vivo , C57BL/6J mice were provided fluoridated water for six weeks with either fluoride free control-chow or 4PBA-containing chow (7 g/kg 4PBA). With few exceptions, enamel microhardness, fluorosis levels, and fluoride concentrations of bone and urine did not differ significantly between fluoride treated animals fed with control-chow or 4PBA-chow. Although 4PBA mitigated high-dose fluoride toxicity in vitro , a diet rich

Health effects of fluoride pollution caused by coal burning

Energy Technology Data Exchange (ETDEWEB)

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

2001-04-23

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

Method and container for reducing pertechnetate

International Nuclear Information System (INIS)

Ruddock, C.F.

1980-01-01

A method of reducing the pertechnetate in TcO 4 - comprises mixing together an aqueous solution of pertechnetate, e.g. the eluant from a technetium generator, metallic tin or an alloy thereof as a reducing agent for the pertechnetate, and a soluble salt of a metal below tin in the electrochemical series, e.g. copper, as an activator for the tin metal reducing agent. A complexing agent for the reduced technetium or a colloid stabiliser may also be included. The pH is preferably 3 to 12. Also claimed is a closed container containing the tin reducing agent, the activator, and the complexant or colloid stabiliser if used, preferably in a freeze-dried sterile state, to which the pertechnetate solution may be added. (author)

Proton microprobe study of tin-polymetallic deposits

Energy Technology Data Exchange (ETDEWEB)

Murao, S [Geological Survey of Japan, Tsukuba, Ibaraki (Japan); Sie, S H; Suter, G F [Commonwealth Scientific and Industrial Research Organisation (CSIRO), North Ryde, NSW (Australia). Div. of Exploration Geoscience

1997-12-31

Tin-polymetallic vein type deposits are a complex mixture of cassiterite and sulfides and they are the main source of technologically important rare metals such as indium and bismuth. Constituent minerals are usually fine grained having wide range of chemical composition and often the elements of interest occur as trace elements not amenable to electron microprobe analysis. PIXE with a proton microprobe can be an effective tool to study such deposits by delineating the distribution of trace elements among carrier minerals. Two representative indium-bearing deposits of tin- polymetallic type, Tosham of India (Cu-ln-Bi-Sn-W-Ag), and Mount Pleasant of Canada (Zn-Cu-In-Bi-Sn-W), were studied to delineate the distribution of medical/high-tech rare metals and to examine the effectiveness of the proton probe analysis of such ore. One of the results of the study indicated that indium and bismuth are present in chalcopyrite in the deposits. In addition to these important rare metals, zinc, copper, arsenic, antimony, selenium, and tin are common in chalcopyrite and pyrite. Arsenopyrite contains nickel, copper, zinc, silver, tin, antimony and bismuth. In chalcopyrite and pyrite, zinc, arsenic, indium, bismuth and lead are richer in Mount Pleasant ore, but silver is higher at Tosham. Also thallium and gold were found only in Tosham pyrite. The Tosham deposit is related to S-type granite, while Mount Pleasant to A-type. It appears that petrographic character of the source magma is one of the factors to determine the trace element distribution in tin-polymetallic deposit. 6 refs., 2 figs.

Proton microprobe study of tin-polymetallic deposits

Energy Technology Data Exchange (ETDEWEB)

Murao, S. [Geological Survey of Japan, Tsukuba, Ibaraki (Japan); Sie, S.H.; Suter, G.F. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), North Ryde, NSW (Australia). Div. of Exploration Geoscience

1996-12-31

Tin-polymetallic vein type deposits are a complex mixture of cassiterite and sulfides and they are the main source of technologically important rare metals such as indium and bismuth. Constituent minerals are usually fine grained having wide range of chemical composition and often the elements of interest occur as trace elements not amenable to electron microprobe analysis. PIXE with a proton microprobe can be an effective tool to study such deposits by delineating the distribution of trace elements among carrier minerals. Two representative indium-bearing deposits of tin- polymetallic type, Tosham of India (Cu-ln-Bi-Sn-W-Ag), and Mount Pleasant of Canada (Zn-Cu-In-Bi-Sn-W), were studied to delineate the distribution of medical/high-tech rare metals and to examine the effectiveness of the proton probe analysis of such ore. One of the results of the study indicated that indium and bismuth are present in chalcopyrite in the deposits. In addition to these important rare metals, zinc, copper, arsenic, antimony, selenium, and tin are common in chalcopyrite and pyrite. Arsenopyrite contains nickel, copper, zinc, silver, tin, antimony and bismuth. In chalcopyrite and pyrite, zinc, arsenic, indium, bismuth and lead are richer in Mount Pleasant ore, but silver is higher at Tosham. Also thallium and gold were found only in Tosham pyrite. The Tosham deposit is related to S-type granite, while Mount Pleasant to A-type. It appears that petrographic character of the source magma is one of the factors to determine the trace element distribution in tin-polymetallic deposit. 6 refs., 2 figs.

Proton microprobe study of tin-polymetallic deposits

International Nuclear Information System (INIS)

Murao, S.; Sie, S.H.; Suter, G.F.

1996-01-01

Tin-polymetallic vein type deposits are a complex mixture of cassiterite and sulfides and they are the main source of technologically important rare metals such as indium and bismuth. Constituent minerals are usually fine grained having wide range of chemical composition and often the elements of interest occur as trace elements not amenable to electron microprobe analysis. PIXE with a proton microprobe can be an effective tool to study such deposits by delineating the distribution of trace elements among carrier minerals. Two representative indium-bearing deposits of tin- polymetallic type, Tosham of India (Cu-ln-Bi-Sn-W-Ag), and Mount Pleasant of Canada (Zn-Cu-In-Bi-Sn-W), were studied to delineate the distribution of medical/high-tech rare metals and to examine the effectiveness of the proton probe analysis of such ore. One of the results of the study indicated that indium and bismuth are present in chalcopyrite in the deposits. In addition to these important rare metals, zinc, copper, arsenic, antimony, selenium, and tin are common in chalcopyrite and pyrite. Arsenopyrite contains nickel, copper, zinc, silver, tin, antimony and bismuth. In chalcopyrite and pyrite, zinc, arsenic, indium, bismuth and lead are richer in Mount Pleasant ore, but silver is higher at Tosham. Also thallium and gold were found only in Tosham pyrite. The Tosham deposit is related to S-type granite, while Mount Pleasant to A-type. It appears that petrographic character of the source magma is one of the factors to determine the trace element distribution in tin-polymetallic deposit. 6 refs., 2 figs

Quadtree of TIN: a new algorithm of dynamic LOD

Science.gov (United States)

Zhang, Junfeng; Fei, Lifan; Chen, Zhen

2009-10-01

Currently, Real-time visualization of large-scale digital elevation model mainly employs the regular structure of GRID based on quadtree and triangle simplification methods based on irregular triangulated network (TIN). TIN is a refined means to express the terrain surface in the computer science, compared with GRID. However, the data structure of TIN model is complex, and is difficult to realize view-dependence representation of level of detail (LOD) quickly. GRID is a simple method to realize the LOD of terrain, but contains more triangle count. A new algorithm, which takes full advantage of the two methods' merit, is presented in this paper. This algorithm combines TIN with quadtree structure to realize the view-dependence LOD controlling over the irregular sampling point sets, and holds the details through the distance of viewpoint and the geometric error of terrain. Experiments indicate that this approach can generate an efficient quadtree triangulation hierarchy over any irregular sampling point sets and achieve dynamic and visual multi-resolution performance of large-scale terrain at real-time.

Assessment of organotin and tin-free antifouling paints contamination in the Korean coastal area.

Science.gov (United States)

Lee, Mi-Ri-Nae; Kim, Un-Jung; Lee, In-Seok; Choi, Minkyu; Oh, Jeong-Eun

2015-10-15

Twelve organotins (methyl-, octyl-, butyl-, and phenyl-tin), and eight tin-free antifouling paints and their degradation products were measured in marine sediments from the Korean coastal area, and Busan and Ulsan bays, the largest harbor area in Korea. The total concentration of tin-free antifouling paints was two- to threefold higher than the total concentration of organotins. Principal component analysis was used to identify sites with relatively high levels of contamination in the inner bay area of Busan and Ulsan bays, which were separated from the coastal area. In Busan and Ulsan bays, chlorothalonil and DMSA were more dominant than in the coastal area. However, Sea-Nine 211 and total diurons, including their degradation products, were generally dominant in the Korean coastal area. The concentrations of tin and tin-free compounds were significantly different between the east and west coasts. Copyright © 2015 Elsevier Ltd. All rights reserved.

In vitro effect of calcium-containing prescription-strength fluoride toothpastes on bovine enamel erosion under hyposalivation-simulating conditions.

Science.gov (United States)

Scaramucci, Taís; Borges, Alessandra B; Lippert, Frank; Zero, Domenick T; Hara, Anderson T

2015-02-01

To evaluate the ability of calcium-containing prescription-strength fluoride (F) toothpastes in preventing enamel erosion under low salivary flow simulating conditions. Enamel and dentin bovine specimens were assigned to the following groups: A - placebo; B - 1,100 ppm F/NaF (Aquafresh Advanced); C - 5,000 ppm F/NaF (Prevident 5000 Booster); D - 5000 ppm F/NaF+calcium sodium phosphosilicate (Topex Renew); and E - 5,000 ppm F/NaF+tri-calcium phosphate (Clinpro 5000). Specimens were positioned in custom-made devices, creating a sealed chamber on the surface, connected to peristaltic pumps. Citric acid was injected into the chamber for 2 minutes, followed by artificial saliva (0.05 ml/minute), for 60 minutes, 4x/day, for 3 days. Aquafresh was also tested under normal salivary flow (0.5 ml/minute), as reference (Group F). Specimens were exposed to the toothpastes for 2 minutes, 2x/day. After cycling, surface loss (SL) and concentration of loosely- and firmly-bound F were determined. Data were analyzed by ANOVA. Results: Group A (placebo) presented highest surface loss (SL), while Group F had the lowest, for both substrates. For enamel, none of the dentifrices differed from Group B or among each other. For dentin, none of the dentifrices differed from Group B, but Group E showed greater protection than Group C. Group E presented the highest F concentrations for both substrates, only matched by Group D for firmly-bound fluoride on enamel. All fluoridated dentifrices tested reduced SL, with no additional benefit from higher F concentrations. Some formulations, especially Clinpro 5000, increased F availability on the dental substrates, but no further erosion protection was observed.

Nutritional and water effect on fluoride uptake and respiration of bean seedlings. [Phaseolus vulgaris

Energy Technology Data Exchange (ETDEWEB)

Applegate, H G; Adams, D F

1960-01-01

Bean plants (Phaseolus vulgaris) were grown in an atmosphere containing 2.0 +/- 0.21 g F /mT (1.6 ppb). The effect of N, P, K, Fe, and Ca deficiencies and the effect of osmotic pressures of 0, 1.5, 3.0, 4.5, 6.0 and 7.5 pounds on fluoride uptake and fluoride-mediated respiration were studied. The data showed that P deficient plants took up more fluoride than plants deficient in any of the other elements studied. Fluoride-mediated respiration was phosphorous dependent, however. Plants low in Fe or K showed increased uptake of fluoride. Nitrogen had no effect on fluoride uptake under the conditions of this experiment. Plants low in Fe showed inhibition of oxygen uptake. This inhibition was accentuated by fluoride. The interactions of N, K and Ca with fluoride on respiration were complex. Neither fluoride uptake nor fluoride-mediated respiration appeared to be linked directly to the water economy of the plants. 14 references, 6 tables.

Vanadocene reactions with mixed acylates of silicon, germanium and tin

International Nuclear Information System (INIS)

Latyaeva, V.N.; Lineva, A.N.; Zimina, S.V.; Gordetsov, A.S.; Dergunov, Yu.I.

1981-01-01

Vanadocene interaction with di-and tri-alkyl (aryl)-derivatives of silicon, tin and germanium is studied. Dibutyltin dibenzoate under mild conditions (20 deg C, toluene) oxidates vanadocene to [CpV(OCOC 6 H 5 ) 2 ] 2 , at that, the splitting off of one Cp group in the form of cyclopentadiene and formation of the products of tin-organic fragment disproportionation (tributyltin benzoate, dibutyltin, metallic tin) take place. Tributyltin benzoate oxidates vanadocene at the mole ratio 2:1 and during prolong heating (120 deg C) in the absence of the solvent, [CpV(OCOC 6 H 5 ) 2 ] 2 and hexabutyldistannate are the products of the reaction. Acetates R 3 SnOCOCH 3 react in the similar way. The reactivity of mono- and diacylates of germanium and silicon decreases in the series of derivatives Sn>Ge>Si [ru

Study of arsenopyrite weathering products in mine wastes from abandoned tungsten and tin exploitations

Energy Technology Data Exchange (ETDEWEB)

Murciego, A. [Department of Geology, Plza. de los Caidos s/n. Salamanca University, 37008 Salamanca (Spain); Alvarez-Ayuso, E., E-mail: esther.alvarez@irnasa.csic.es [Department of Environmental Geochemistry, IRNASA (CSIC), Apdo. 257, 37071 Salamanca (Spain); Pellitero, E. [Department of Geology, Plza. de los Caidos s/n. Salamanca University, 37008 Salamanca (Spain); Rodriguez, M.A. [Faculty of Sciences, Crystallography and Mineralogy Area, Avd. Elvas s/n. Extremadura University, 06071 Badajoz (Spain); Garcia-Sanchez, A. [Department of Environmental Geochemistry, IRNASA (CSIC), Apdo. 257, 37071 Salamanca (Spain); Tamayo, A.; Rubio, J.; Rubio, F. [Ceramic and Glass Institute (CSIC), c/Kelsen, 5, 28049 Cantoblanco, Madrid (Spain); Rubin, J. [Material Science Institute of Aragon, CSIC-Zaragoza University, c/Maria de Luna 3, 50009 Zaragoza (Spain)

2011-02-15

Arsenopyrite-rich wastes from abandoned tungsten and tin exploitations were studied to determine the composition and characteristics of the secondary phases formed under natural weathering conditions so as to assess their potential environmental risk. Representative weathered arsenopyrite-bearing rock wastes collected from the mine dumps were analysed using the following techniques: X-ray powder diffraction (XRD) analysis, polarizing microscopy analysis, electron microprobe analysis (EMPA) and microRaman and Moessbauer spectroscopies. Scorodite, pharmacosiderite and amorphous ferric arsenates (AFA) with Fe/As molar ratios in the range 1.2-2.5 were identified as secondary arsenic products. The former showed to be the most abundant and present in the different studied mining areas. Its chemical composition showed to vary in function of the original surrounding rock mineralogy in such a way that phosphoscorodite was found as the mineral variety present in apatite-containing geoenvirons. Other ever-present weathering phases were goethite and hydrous ferric oxides (HFO), displaying, respectively, As retained amounts about 1 and 20% (expressed as As{sub 2}O{sub 5}). The low solubility of scorodite, the relatively low content of AFA and the formation of compounds of variable charge, mostly of amorphous nature, with high capacity to adsorb As attenuate importantly the dispersion of this element into the environment from these arsenopyrite-bearing wastes.

Study of arsenopyrite weathering products in mine wastes from abandoned tungsten and tin exploitations

International Nuclear Information System (INIS)

Murciego, A.; Alvarez-Ayuso, E.; Pellitero, E.; Rodriguez, M.A.; Garcia-Sanchez, A.; Tamayo, A.; Rubio, J.; Rubio, F.; Rubin, J.

2011-01-01

Arsenopyrite-rich wastes from abandoned tungsten and tin exploitations were studied to determine the composition and characteristics of the secondary phases formed under natural weathering conditions so as to assess their potential environmental risk. Representative weathered arsenopyrite-bearing rock wastes collected from the mine dumps were analysed using the following techniques: X-ray powder diffraction (XRD) analysis, polarizing microscopy analysis, electron microprobe analysis (EMPA) and microRaman and Moessbauer spectroscopies. Scorodite, pharmacosiderite and amorphous ferric arsenates (AFA) with Fe/As molar ratios in the range 1.2-2.5 were identified as secondary arsenic products. The former showed to be the most abundant and present in the different studied mining areas. Its chemical composition showed to vary in function of the original surrounding rock mineralogy in such a way that phosphoscorodite was found as the mineral variety present in apatite-containing geoenvirons. Other ever-present weathering phases were goethite and hydrous ferric oxides (HFO), displaying, respectively, As retained amounts about 1 and 20% (expressed as As 2 O 5 ). The low solubility of scorodite, the relatively low content of AFA and the formation of compounds of variable charge, mostly of amorphous nature, with high capacity to adsorb As attenuate importantly the dispersion of this element into the environment from these arsenopyrite-bearing wastes.

SOLVENT FIRE BY-PRODUCTS

Energy Technology Data Exchange (ETDEWEB)

Walker, D; Samuel Fink, S

2006-05-22

Southwest Research Institute (SwRI) conducted a burn test of the Caustic-Side Solvent Extraction (CSSX) solvent to determine the combustion products. The testing showed hydrogen fluoride gas is not a combustion product from a solvent fire when up to 70% of the solvent is consumed. The absence of HF in the combustion gases may reflect concentration of the modifier containing the fluoride groups in the unburned portion. SwRI reported results for other gases (CO, HCN, NOx, formaldehyde, and hydrocarbons). The results, with other supporting information, can be used for evaluating the consequences of a facility fire involving the CSSX solvent inventory.

Identification of an operon involved in fluoride resistance in Enterobacter cloacae FRM

OpenAIRE

Liu, Xiaoqing; Tian, Jian; Liu, Lihui; Zhu, Tao; Yu, Xiaoxia; Chu, Xiaoyu; Yao, Bin; Wu, Ningfeng; Fan, Yunliu

2017-01-01

Fluorine is ubiquitous and the most active non-metal element in nature. While many microorganisms have developed fluoride resistance as a result of the widespread and prolonged application of oral hygiene products, the mechanisms used by these organisms to overcome fluoride toxicity are incompletely understood. In this study, a fluoride-resistant strain, Enterobacter cloacae FRM, was identified which could grow well at a fluoride concentration of 4,000?mg/L. According to comparative genomics,...

Industrial fluoride pollution: chronic fluoride poisoning in Cornwall Island cattle

Energy Technology Data Exchange (ETDEWEB)

Krook, L.; Maylin, G.A.

1979-04-01

An aluminum plant on the south bank of the St. Lawrence River, southwest of Cornwall Island, Ontario, Canada, has emitted 0.816 metric tons of fluoride daily since 1973. Considerably higher amounts were emitted from 1959 to 1973. The plant was designated as the major source of fluoride emissions impacting on Cornwall Island. Cattle located on this island showed signs of chronic fluoride poisoning. This poisoning was manifested clinically by stunted growth and dental fluorosis to a degree of severe interference with drinking and mastication. This Cornwall Island herds study indicates that the established tolerance level of fluoride for performance of dairy and beef cattle is not valid since the tolerance level was set based on experiments with healthy calves which were exposed to dietary fluoride from 3 to 4 months of age and not on cattle which were chronically exposed to fluoride from conception to death. 56 references.

A health risk assessment for fluoride in Central Europe.

Science.gov (United States)

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

2007-04-01

Like many elements, fluorine (which generally occurs in nature as fluoride) is beneficial to human health in trace amounts, but can be toxic in excess. The links between low intakes of fluoride and dental protection are well known; however, fluoride is a powerful calcium-seeking element and can interfere with the calcified structure of bones and teeth in the human body at higher concentrations causing dental or skeletal fluorosis. One of the main exposure routes is via drinking water and the World Health Organisation currently sets water quality guidelines for the element. In Central Europe, groundwater resources that exceed the guideline value of 1.5 mg l-1 are widespread and effects on health of high fluoride in water have been reported. The aim of the current project was to develop a geographic information system (GIS) to aid the identification of areas where high-fluoride waters and fluorosis may be a problem; hence, where water treatment technologies should be targeted. The development of the GIS was based upon the collation and digitisation of existing information relevant to fluoride risk in Ukraine, Moldova, Hungary and Slovakia assembled for the first time in a readily accessible form. In addition, geochemistry and health studies to examine in more detail the relationships between high-fluoride drinking waters and health effects in the population were carried out in Moldova and Ukraine demonstrating dental fluorosis prevalence rates of 60-90% in adolescents consuming water containing 2-7 mg l-1 fluoride.

Occurrence of fluoride in ground waters of Saudi Arabia

Science.gov (United States)

Alabdulaaly, Abdulrahman I.; Al-Zarah, Abdullah I.; Khan, Mujahid A.

2013-09-01

The presence of elevated levels of fluoride in groundwater is considered a global problem. Fluoride in water derives mainly from dissolution of natural minerals in the rocks and soils with which water interacts. The most common fluorine-bearing minerals are fluorite, apatite and micas. Anthropogenic sources of fluoride include agricultural fertilizers and combustion of coal. In the present research, a survey of wells ( n = 1,060) was undertaken in all the 13 regions of the Kingdom of Saudi Arabia to assess the contained fluoride (F) levels. The results indicated variation in fluoride levels from 0.10 to 5.4 mg/L as F throughout the kingdom. The average fluoride levels in milligrams per liter as F were as follows in descending order: 1.80 (Hadwood Shamalyah), 1.37 (Hail), 1.33 (Eastern Province), 1.16 (Al Jouf), 1.11 (Qassim), 1.01 (Riyadh), 0.90 (Madina Al Munnawara), 0.81 (Tabouk), 0.74 (Makkah Al- Mukaramma), 0.73 (Jizan), 0.66 (Asir), 0.64 (Najran), and 0.60 (Al Baha). The results indicated that fluoride levels exceeded the USEPA maximum contaminant limits for drinking water (4 mg/L) in several wells ( n = 7) in different regions of the kingdom and that 13.96 % of the wells exceeded the World Health Organization recommended levels (1.5 mg/L). The results were also compared with the secondary USEPA contaminant standards of 2.0 mg/L for fluorides.

Electrosynthesis of tantalum borides in oxygen-free and oxygen-containing fluoride melts

DEFF Research Database (Denmark)

Polyakova, L.P.; Polyakov, E.G.; Makarova, O.V.

2001-01-01

Results of electrosynthesis of tantalum borides in fluoride and oxyfluoride melts are compared. It is shown that the single-phase X-ray-amorphous micro-layered coatings form only in the latter case. Linear and square-wave voltammetry, complemented by X-ray diffraction analysis, IR spectroscopy...

Milk fluoridation for the prevention of dental caries

Directory of Open Access Journals (Sweden)

Jolán Bánóczy

2013-11-01

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

Milk fluoridation for the prevention of dental caries.

Science.gov (United States)

Bánóczy, Jolán; Rugg-Gunn, Andrew; Woodward, Margaret

2013-11-01

The aim of this review is to give an overview of 55 years experience of milk fluoridation and draw conclusions about the applicability of the method. Fluoridated milk was first investigated in the early 1950s, almost simultaneously in Switzerland, the USA and Japan. Stimulated by the favourable results obtained from these early studies, the establishment of The Borrow Dental Milk Foundation (subsequently The Borrow Foundation) in England gave an excellent opportunity for further research, both clinical and non-clinical, and a productive collaboration with the World Health Organization which began in the early 1980s. Numerous peer-reviewed publications in international journals showed clearly the bioavailability of fluoride in various types of milk. Clinical trials were initiated in the 1980s - some of these can be classed as randomised controlled trials, while most of the clinical studies were community preventive programmes. These evaluations showed clearly that the optimal daily intake of fluoride in milk is effective in preventing dental caries. The amount of fluoride added to milk depends on background fluoride exposure and age of the children: commonly in the range 0.5 to 1.0 mg per day. An advantage of the method is that a precise amount of fluoride can be delivered under controlled conditions. The cost of milk fluoridation programmes is low, about € 2 to 3 per child per year. Fluoridation of milk can be recommended as a caries preventive measure where the fluoride concentration in drinking water is suboptimal, caries experience in children is significant, and there is an existing school milk programme. Copyright © 2013 by Academy of Sciences and Arts of Bosnia and Herzegovina.

Selective Recovery of Mushistonite from Gravity Tailings of Copper–Tin Minerals in Tajikistan

Directory of Open Access Journals (Sweden)

Lei Sun

2017-12-01

Full Text Available Tajikistan has abundant copper–tin resources. In this study, mineralogical analysis of copper–tin ores from the Mushiston deposit of Tajikistan indicates that tin mainly occurred in mushistonite, cassiterite, and stannite, while copper mainly occurred in mushistonite, malachite, azurite, and stannite. The total grades of tin (Sn and copper (Cu were 0.65% and 0.66%, respectively, and the dissemination size of copper–tin minerals ranged from 4 μm to over 200 μm. Coarse particles of copper–tin minerals were partially recovered by shaking table concentrators with a low recovery rate. Based on the mineralogical analysis, flotation recovery was used for the first time on the fine particles of copper–tin minerals, including mushistonite, from shaking table tailings. Single factor flotation experiments, open circuit flotation tests, and closed circuit flotation tests were performed to determine the optimized flotation conditions. Results indicated that benzohydroxamic acid (C6H5CONHOH and lead nitrate could effectively recover the mushistonite, cooperating with other depressants. The final concentrate contained 13.28% Sn, with a recovery rate of 61.56%, and 18.51% Cu, with a recovery rate of 86.52%. This method proved effective for the exploitation and use of this type of copper–tin resource in Tajikistan.

Metabolomic Effects of Xylitol and Fluoride on Plaque Biofilm in Vivo

Science.gov (United States)

Takahashi, N.; Washio, J.

2011-01-01

Dental caries is initiated by demineralization of the tooth surface through acid production from sugar by plaque biofilm. Fluoride and xylitol have been used worldwide as caries-preventive reagents, based on in vitro-proven inhibitory mechanisms on bacterial acid production. We attempted to confirm the inhibitory mechanisms of fluoride and xylitol in vivo by performing metabolome analysis on the central carbon metabolism in supragingival plaque using the combination of capillary electrophoresis and a time-of-flight mass spectrometer. Fluoride (225 and 900 ppm F−) inhibited lactate production from 10% glucose by 34% and 46%, respectively, along with the increase in 3-phosphoglycerate and the decrease in phosphoenolpyruvate in the EMP pathway in supragingival plaque. These results confirmed that fluoride inhibited bacterial enolase in the EMP pathway and subsequently repressed acid production in vivo. In contrast, 10% xylitol had no effect on acid production and the metabolome profile in supragingival plaque, although xylitol 5-phosphate was produced. These results suggest that xylitol is not an inhibitor of plaque acid production but rather a non-fermentative sugar alcohol. Metabolome analyses of plaque biofilm can be applied for monitoring the efficacy of dietary components and medicines for plaque biofilm, leading to the development of effective plaque control. PMID:21940519

Metabolomic effects of xylitol and fluoride on plaque biofilm in vivo.

Science.gov (United States)

Takahashi, N; Washio, J

2011-12-01

Dental caries is initiated by demineralization of the tooth surface through acid production from sugar by plaque biofilm. Fluoride and xylitol have been used worldwide as caries-preventive reagents, based on in vitro-proven inhibitory mechanisms on bacterial acid production. We attempted to confirm the inhibitory mechanisms of fluoride and xylitol in vivo by performing metabolome analysis on the central carbon metabolism in supragingival plaque using the combination of capillary electrophoresis and a time-of-flight mass spectrometer. Fluoride (225 and 900 ppm F(-)) inhibited lactate production from 10% glucose by 34% and 46%, respectively, along with the increase in 3-phosphoglycerate and the decrease in phosphoenolpyruvate in the EMP pathway in supragingival plaque. These results confirmed that fluoride inhibited bacterial enolase in the EMP pathway and subsequently repressed acid production in vivo. In contrast, 10% xylitol had no effect on acid production and the metabolome profile in supragingival plaque, although xylitol 5-phosphate was produced. These results suggest that xylitol is not an inhibitor of plaque acid production but rather a non-fermentative sugar alcohol. Metabolome analyses of plaque biofilm can be applied for monitoring the efficacy of dietary components and medicines for plaque biofilm, leading to the development of effective plaque control.

The Anticaries Efficacy of a 1.5% Arginine and Fluoride Toothpaste.

Science.gov (United States)

Wolff, M S; Schenkel, A B

2018-02-01

Dental caries remains a world-wide disease despite the global distribution of fluoride. It has become apparent that the introduction of significant levels of sugar (fermentable carbohydrate) into the diet has resulted in a change in the biofilm, encouraging acid formation. Further, there has been a shift in the microbiota in the biofilm to a flora that produces acid, and thrives and reproduces in an acidic environment. The management of caries activity under these conditions has focused on brushing to remove the biofilm with fluoride pastes, and high-dose fluoride treatments. Kleinberg, in the 1970s, identified an arginine-containing compound in saliva that several oral biofilm bacterial species metabolize to produce base. Multiple in situ and in vivo studies have been conducted, and have discussed the ability of multiple bacteria to increase the resting pH of the biofilm and even reduce the decrease in pH when the biofilm is challenged with glucose. This shift in resting pH can shift the level of caries formation by the biofilm. Here, we present 8 clinical studies, with different clinical designs, measuring different clinical outcomes, for a diverse, world-wide population. Each of these studies demonstrates reductions in caries formation beyond that seen with fluoride alone and several demonstrate the reversal of early caries lesions. Significant clinical research has been shown that 1.5% arginine combined with fluoride toothpaste has superior anti-caries efficacy to toothpaste containing fluoride alone.

Are there good reasons for fluoride labelling of food and drink?

Science.gov (United States)

Zohoori, F V; Maguire, A

2018-02-23

This opinion piece highlights the importance of controlling systemic fluoride intake from food and drink in early childhood to minimise risk of dental fluorosis whilst maximising caries prevention; the wide range of fluoride contents found in a study of commercially-available food and drinks; and the need for comprehensive fluoride labelling on food and drink products in the UK, particularly those used by infants and young children.

Growth kinetics for the precipitation of zirconium hydroxide from aqueous zirconium and tin bearing solutions by the addition of ammonium hydroxide

Energy Technology Data Exchange (ETDEWEB)

Carleson, T.E. [Idaho Univ., Moscow, ID (United States). Dept. of Chemical Engineering; Chipman, N.A. [Westinghouse Idaho Nuclear Co., Inc., Idaho Falls, ID (United States)

1989-09-11

The precipitation of zirconium hydroxide from an aqueous solution of ammonium hexafluorozirconate occurs rapidly upon addition of ammonium hydroxide. Experimental data indicate growth and nucleation rates between 0.06 and 0.28 microns/minute and around 10 {times} 107 number/L-min, respectively. Experiments with a mixed suspension mixed product removal crystallizer for concentrations of reactants of about 0.05 M ammonium hexafluorozirconate precipitating with 0.002 M ammonium hydroxide showed apparent nonlinear growth rates in some cases but not others. Batch studies indicated that growth rate dispersion is probably not present. When the AFL nonlinear model was used to fit the data, the power coefficient obtained was greater than 1, in disagreement with theory. In addition, for some of the data ``S`` shaped curves of the logarithm of the cumulative number greater than versus size were obtained. These curves can not be fit by the AFL model. A program developed at the University of Arizona was used to simulate the crystallization runs. The program results indicated that some of the nonlinear behavior may be attributed to transient conditions. Experimental data also illustrated this behavior. The effect of trace amounts of tin fluoride (0.008 M) on the nucleation and growth kinetics was also evaluated. For some residence times, the presence of tin resulted in reduced median particle diameters, higher growth rates, and lower number counts.

Purification of Drinking Water from Fluorides by Reverse Osmosis

Directory of Open Access Journals (Sweden)

Aleksander A.

2018-03-01

Full Text Available Introduction: An important task in the sphere of sanitary and epidemiological welfare of the population of the Russian Federation is provision of drinking water. Tap water must not contain pathogenic bacteria and dangerous chemicals. Purification systems regulate the concentration of fluoride ions in drinking water. The aim of this paper is to study the possibility of purifying tap water from fluoride ions by reverse osmosis. Materials and Methods: We used the Alfa Laval PilotUnit 2.5 "RO/NF with a set of spiral-type membrane elements RO99-2517/48 to remove fluoride ions. We measured the concentration of fluoride ions by the potentiometric method using the Hanna HI 2211 (pH/mV/T. Fluoride-selective electrode ELIS 131 F was used as an indicator electrode and the standard chloride-silver electrode EVL-1M3 was used as a reference electrode. Both the calibration and buffer solutions were prepared from chemically pure reagents and A. R. purity for analysis reagents according to GOST 4386-89. Results: A single passage of water through the reverse osmosis membrane reduced the concentration of fluoride ions from 2.29 ± 0.02 to 0.240 ± 0.015 mg/l. Double passage of water reduced the concentration by a factor of two. As the concentration of fluoride ions increased in the retentate, the concentration in the filtrate slightly increased too. Purification of water reduced the concentration of fluoride ions from 20 mg/l, to 0.5 mg/l. Discussion and Conclusions: Thus, using the Alfa Laval PilotUnit 2.5" RO/NF with a set of spiral-type membrane elements RO99-2517/48 filters tap water of ions of fluoride to the maximum allowable concentration. This study opens the perspective of using reverse osmosis to purify tap water with high concentration of fluoride ions.

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

Directory of Open Access Journals (Sweden)

Cecília Claudia Costa Ribeiro

2008-01-01

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

Composition, structure and electrical properties of alumina barrier layers grown in fluoride-containing oxalic acid solutions

Energy Technology Data Exchange (ETDEWEB)

Jagminas, A. [Institute of Chemistry, A. Gostauto 9, LT-01108 Vilnius (Lithuania)], E-mail: jagmin@ktl.mii.lt; Vrublevsky, I. [Department of Microelectricals, Belarusian State University of Informatics and Radioelectricals, 6 Brovka Street, Minsk 220013 (Belarus); Kuzmarskyte, J.; Jasulaitiene, V. [Institute of Chemistry, A. Gostauto 9, LT-01108 Vilnius (Lithuania)

2008-04-15

The composition, structure and electrical properties of alumina barrier layers grown by anodic oxidation in F{sup -}-containing (FC) and F{sup -}-free (FF) oxalic acid solutions were studied using the re-anodizing/dissolution technique, Fourier-transformed infrared and X-ray photoelectron spectroscopy. These results confirmed formation in FC anodizing solutions of films structurally different from ones grown in FF oxalic acid baths. It was found that the barrier layer of FC alumina films is composed of two layers differing in the dissolution rate. These differences are related to the formation in the FC electrolyte of a barrier layer composed of a more microporous outer part and a thin, non-porous and non-scalloped inner part consisting of aluminum oxide and aluminum fluoride.

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

Science.gov (United States)

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

2013-11-19

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

JNK and NADPH Oxidase Involved in Fluoride-Induced Oxidative Stress in BV-2 Microglia Cells

Directory of Open Access Journals (Sweden)

Ling Yan

2013-01-01

Full Text Available Excessive fluoride may cause central nervous system (CNS dysfunction, and oxidative stress is a recognized mode of action of fluoride toxicity. In CNS, activated microglial cells can release more reactive oxygen species (ROS, and NADPH oxidase (NOX is the major enzyme for the production of extracellular superoxide in microglia. ROS have been characterized as an important secondary messenger and modulator for various mammalian intracellular signaling pathways, including the MAPK pathways. In this study we examined ROS production and TNF-α, IL-1β inflammatory cytokines releasing, and the expression of MAPKs in BV-2 microglia cells treated with fluoride. We found that fluoride increased JNK phosphorylation level of BV-2 cells and pretreatment with JNK inhibitor SP600125 markedly reduced the levels of intracellular and NO. NOX inhibitor apocynin and iNOS inhibitor SMT dramatically decreased NaF-induced ROS and NO generations, respectively. Antioxidant melatonin (MEL resulted in a reduction in JNK phosphorylation in fluoride-stimulated BV-2 microglia. The results confirmed that NOX and iNOS played an important role in fluoride inducing oxidative stress and NO production and JNK took part in the oxidative stress induced by fluoride and meanwhile also could be activated by ROS in fluoride-treated BV-2 cells.

JNK and NADPH Oxidase Involved in Fluoride-Induced Oxidative Stress in BV-2 Microglia Cells

Science.gov (United States)

Yan, Ling; Liu, Shengnan; Wang, Chen; Wang, Fei; Song, Yingli; Yan, Nan; Xi, Shuhua; Liu, Ziyou; Sun, Guifan

2013-01-01

Excessive fluoride may cause central nervous system (CNS) dysfunction, and oxidative stress is a recognized mode of action of fluoride toxicity. In CNS, activated microglial cells can release more reactive oxygen species (ROS), and NADPH oxidase (NOX) is the major enzyme for the production of extracellular superoxide in microglia. ROS have been characterized as an important secondary messenger and modulator for various mammalian intracellular signaling pathways, including the MAPK pathways. In this study we examined ROS production and TNF-α, IL-1β inflammatory cytokines releasing, and the expression of MAPKs in BV-2 microglia cells treated with fluoride. We found that fluoride increased JNK phosphorylation level of BV-2 cells and pretreatment with JNK inhibitor SP600125 markedly reduced the levels of intracellular O2 ·− and NO. NOX inhibitor apocynin and iNOS inhibitor SMT dramatically decreased NaF-induced ROS and NO generations, respectively. Antioxidant melatonin (MEL) resulted in a reduction in JNK phosphorylation in fluoride-stimulated BV-2 microglia. The results confirmed that NOX and iNOS played an important role in fluoride inducing oxidative stress and NO production and JNK took part in the oxidative stress induced by fluoride and meanwhile also could be activated by ROS in fluoride-treated BV-2 cells. PMID:24072958

Performance of semi-continuous membrane bioreactor in biogas production from toxic feedstock containing D-Limonene.

Science.gov (United States)

Wikandari, Rachma; Youngsukkasem, Supansa; Millati, Ria; Taherzadeh, Mohammad J

2014-10-01

A novel membrane bioreactor configuration containing both free and encased cells in a single reactor was proposed in this work. The reactor consisted of 120g/L of free cells and 120g/L of encased cells in a polyvinylidene fluoride membrane. Microcrystalline cellulose (Avicel) and d-Limonene were used as the models of substrate and inhibitor for biogas production, respectively. Different concentrations of d-Limonene i.e., 1, 5, and 10g/L were tested, and an experiment without the addition of d-Limonene was prepared as control. The digestion was performed in a semi-continuous thermophilic reactor for 75 days. The result showed that daily methane production in the reactor with the addition of 1g/L d-Limonene was similar to that of control. A lag phase was observed in the presence of 5g/L d-Limonene; however, after 10 days, the methane production increased and reached a similar production to that of the control after 15 days. Copyright © 2014 Elsevier Ltd. All rights reserved.

Manufacturing of Dysprosium-Iron Alloys by Electrolysis in Fluoride-Based Electrolytes: Oxide Solubility Determinations

Science.gov (United States)

Martinez, Ana Maria; Støre, Anne; Osen, Karen Sende

2018-04-01

Electrolytic production of light rare earth elements and alloys takes place in a fluoride-based electrolyte using rare earth oxides as raw material. The optimization of this method, mainly in terms of the energy efficiency and environmental impact control, is rather challenging. Anode effects, evolution of fluorine-containing compounds, and side cathode reactions could largely be minimized by a good control of the amount of rare earth oxide species dissolved in the fluoride-based electrolyte and their dissolution rate. The oxide content of the fluoride melts REF3-LiF (RE = Nd, Dy) at different compositions and temperatures were experimentally determined by carbothermal analysis of melt samples. The highest solubility values of oxide species, added as Dy2O3 and Dy2(CO3)3, were obtained to be of ca. 3 wt pct (expressed as Dy2O3) in the case of the equimolar DyF3-LiF melt at 1323 K (1050 °C). The oxide saturation values increased with the amount of REF3 present in the molten bath and the working temperature.

No Calcium-Fluoride-Like Deposits Detected in Plaque Shortly after a Sodium Fluoride Mouthrinse

OpenAIRE

Vogel, G.L.; Tenuta, L.M.A.; Schumacher, G.E.; Chow, L.C.

2010-01-01

Plaque ‘calcium-fluoride-like’ (CaF2-like) and fluoride deposits held by biological/bacterial calcium fluoride (Ca-F) bonds appear to be the source of cariostatic concentrations of fluoride in plaque fluid. The aim of this study was to quantify the amounts of plaque fluoride held in these reservoirs after a sodium fluoride rinse. 30 and 60 min after a 228 μg/g fluoride rinse, plaque samples were collected from 11 volunteers. Each sample was homogenized, split into 2 aliquots (aliquots 1 and 2...

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

Directory of Open Access Journals (Sweden)

Kelly Polido Kaneshiro Olympio

2009-06-01

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

Influence of noble metals alloying additions on the corrosion behaviour of titanium in a fluoride-containing environment.

Science.gov (United States)

Rosalbino, F; Delsante, S; Borzone, G; Scavino, G

2012-05-01

Titanium alloys exhibit excellent corrosion resistance in most aqueous media due to the formation of a stable oxide film, and some of these alloys (particularly Ti-6Al-7Nb) have been chosen for surgical and odontological implants for their resistance and biocompatibility. Treatment with fluorides (F(-)) is known to be the main method for preventing plaque formation and dental caries. Toothpastes, mouthwashes, and prophylactic gels can contain from 200 to 20,000 ppm F(-) and can affect the corrosion behaviour of titanium alloy devices present in the oral cavity. In this work, the electrochemical corrosion behaviour of Ti-1M alloys (M = Ag, Au, Pd, Pt) was assessed in artificial saliva of pH = 3.0 containing 910 ppm F(-) (0.05 M NaF) through open circuit potential, E(OC), and electrochemical impedance spectroscopy (EIS) measurements. The corrosion behaviour of the Ti-6Al-7Nb commercial alloy was also evaluated for comparison. E (OC) measurements show an active behaviour for all the titanium alloys in fluoridated acidified saliva due to the presence of significant concentrations of HF and HF(2) (-) species that dissolve the spontaneous air-formed oxide film giving rise to surface activation. However, an increase in stability of the passive oxide layer and consequently a decrease in surface activation is observed for the Ti-1M alloys. This behaviour is confirmed by EIS measurements. In fact, the Ti-6Al-7Nb alloy exhibits lower impedance values as compared with Ti-1M alloys, the highest values being measured for the Ti-1Au alloy. The experimental results show that the corrosion resistance of the studied Ti-1M alloys is similar to or better than that of Ti-6Al-7Nb alloy currently used as biomaterial, suggesting their potential for dental applications.

Fluoride Rinses, Gels and Foams

DEFF Research Database (Denmark)

Twetman, Svante; Keller, Mette K

2016-01-01

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

The effect of a toothpaste containing 2% zinc citrate and 0.3% Triclosan on bacterial viability and plaque growth in vivo compared to a toothpaste containing 0.3% Triclosan and 2% copolymer.

Science.gov (United States)

Adams, S E; Theobald, A J; Jones, N M; Brading, M G; Cox, T F; Mendez, A; Chesters, D M; Gillam, D G; Hall, C; Holt, J

2003-12-01

To compare the antimicrobial efficacy and effect on plaque growth of a new silica-based fluoride toothpaste containing 2% zinc citrate/ 0.3% Triclosan with a silica-based fluoride toothpaste containing 0.3% Triclosan/2% copolymer. In Study 1, plaque was collected after one week's use of each toothpaste and assessed for bacterial viability, live/ dead ratio and microbial membrane integrity. In study 2, plaque was measured immediately and 18 hours after a single brushing with the specified toothpastes. The 2% zinc citrate/0.3% Triclosan formulation significantly reduced the total number of viable aerobic and anaerobic bacteria (p = 0.0223 and p = 0.0443 respectively) compared to the 0.3% Triclosan/2% copolymer formulation. Both toothpastes increased the bacterial membrane permeability significantly. However, the proportion of live bacteria for the 2% zinc citrate/0.3% Triclosan product was significantly reduced (p plaque growth 18 hours after using the 2% zinc citrate/0.3% Triclosan toothpaste compared to the 0.3% Triclosan/2% copolymer toothpaste (p fluoride toothpaste containing 2% zinc citrate and 0.3% Triclosan, significantly reduced the viability of plaque bacteria compared to a fluoride toothpaste containing 0.3% Triclosan/ 2% copolymer 12 hours after brushing. In addition, a clinical plaque growth study confirmed that this anti-microbial efficacy leads to a significant reduction in plaque growth.

INTERACTION OF FLUORIDE COMPLEXES DERIVED FROM GLASS-IONOMER CEMENTS WITH HYDROXYAPATITE

Directory of Open Access Journals (Sweden)

Lewis S. M.

2013-09-01

Full Text Available A study has been undertaken of the interaction of complexed fluoride extracted from glass-ionomer dental cements with synthetic hydroxyapatite powder. Extracts were prepared from two commercial glass-ionomers (Fuji IX and ChemFlex under both neutral and acidic conditions. They were analysed by ICP-OES and by fluoride-ion selective electrode with and without added TISAB to decomplex the fluoride. The pH of the acid extracts was 4, conditions under which fluoride complexes with protons as HF or HF2-, it also complexes with aluminium, which was found to be present in higher amounts in the acid extracts. Fluoride was found to be almost completely complexed in acid extracts, but not in neutral extracts, which contained free fluoride ions. Exposure of these extracts to synthetic hydroxyapatite powder showed that fluoride was taken up rapidly (within 5 minutes, whether or not it was complexed. SEM (EDAX study of recovered hydroxyapatite showed only minute traces of aluminium taken up under all conditions. This showed that aluminium interacts hardly at all with hydroxyapatite, and hence is probably not involved in the remineralisation process.

Uranyl fluoride luminescence in acidic aqueous solutions

International Nuclear Information System (INIS)

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

1996-01-01

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

Effect of containers on the quality of Chemlali olive oil during storage.

Science.gov (United States)

Gargouri, Boutheina; Zribi, Akram; Bouaziz, Mohamed

2015-04-01

This study is undertaken to determine the storage stability of Chemlali extra-virgin olive oil (EVOO) in different containers such as clear and dark glass bottles, polyethylene (PE) and tin containers. The different oil samples were stored under light at room temperature. Quality parameters monitored during a 6-month-storage period included: acidity, peroxide value (PV), spectrophotometric indices (K232 and K270), chlorophyll and carotene pigments, fatty acids and sterol compositions, total phenols, Rancimat induction time as well as sensory evaluation. Tin containers and dark glass bottles recorded the lowest oxidation values. In addition, oil packed in tin containers and dark glass bottles showed better physicochemical and organoleptic characteristics than that stored in clear glass bottles and PE containers. A significant decrease (p containers. Such results proved that the storage of oil in tin containers and dark glass bottles appeared most adequate, and showed a gradual loss of quality during storage, especially in PE containers and clear glass bottles. This study has shown that the best packaging materials for the commercial packing of Chemlali extra-virgin olive oil are tin containers and dark glass bottles.

Preventing Tooth Decay: A Guide for Implementing Self-Applied Fluoride in Schools.

Science.gov (United States)

National Inst. of Dental Research (NIH), Bethesda, MD.

This guidebook was developed to assist citizens in initiating programs to prevent tooth decay in young children through the use of fluoridation. It contains outlines for determining the needs of the school and community for fluoride in drinking water, and presents the various steps and activities that are necessary for developing and implementing…

Fluoride and Oral Health.

Science.gov (United States)

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

2016-06-01

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

LIQUID METAL COMPOSITIONS CONTAINING URANIUM

Science.gov (United States)

Teitel, R.J.

1959-04-21

Liquid metal compositions containing a solid uranium compound dispersed therein is described. Uranium combines with tin to form the intermetallic compound USn/sub 3/. It has been found that this compound may be incorporated into a liquid bath containing bismuth and lead-bismuth components, if a relatively small percentage of tin is also included in the bath. The composition has a low thermal neutron cross section which makes it suitable for use in a liquid metal fueled nuclear reactor.

Phononic band gap and wave propagation on polyvinylidene fluoride-based acoustic metamaterials

Directory of Open Access Journals (Sweden)

Oral Oltulu

2016-12-01

Full Text Available In the present work, the acoustic band structure of a two-dimensional phononic crystal (PC containing an organic ferroelectric (PVDF-polyvinylidene fluoride and topological insulator (SnTe was investigated by the plane-wave-expansion (PWE method. Two-dimensional PC with square lattices composed of SnTe cylindrical rods embedded in the PVDF matrix is studied to find the allowed and stop bands for the waves of certain energy. Phononic band diagram ω = ω(k for a 2D PC, in which non-dimensional frequencies ωa/2πc (c-velocity of wave were plotted vs. the wavevector k along the Г–X–M–Г path in the square Brillouin zone shows five stop bands in the frequency range between 10 and 110 kHz. The ferroelectric properties of PVDF and the unusual properties of SnTe as a topological material give us the ability to control the wave propagation through the PC over a wide frequency range of 103–106 Hz. SnTe is a discrete component that allows conducting electricity on its surface but shows insulator properties through its bulk volume. Tin telluride is considered as an acoustic topological insulator as the extension of topological insulators into the field of “topological phononics”.

Discovery of the calcium, indium, tin, and platinum isotopes

International Nuclear Information System (INIS)

Amos, S.; Gross, J.L.; Thoennessen, M.

2011-01-01

Currently, twenty-four calcium, thirty-eight indium, thirty-eight tin, and thirty-nine platinum isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented. - Highlights: Documentation of the discovery of all calcium, indium, tin and platinum isotopes. → Summary of author, journal, year, place and country of discovery for each isotope. → Brief description of discovery history of each isotope.

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

International Nuclear Information System (INIS)

Meublat, L.

1989-10-01

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

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

International Nuclear Information System (INIS)

Meublat, L.

1989-01-01

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

Effects of TiN nanoparticles on the microstructure and properties of W–30Cu composites prepared via electroless plating and powder metallurgy

International Nuclear Information System (INIS)

Huang, Li-Mei; Luo, Lai-Ma; Zhao, Mei-Ling; Luo, Guang-Nan; Zhu, Xiao-Yong; Cheng, Ji-Gui; Zan, Xiang; Wu, Yu-Cheng

2015-01-01

Highlights: • TiN-doped W–Cu composite was successfully prepared by electroless plating and powder metallurgy. • TiN-doped W–Cu significantly affected the microstructure and properties of the composites. • W–Cu composite with 0.25 wt.% TiN possesses the best comprehensive performance. - Abstract: W–30Cu/(0, 0.25, 0.5, 1, and 2) wt.% TiN composites were prepared via electroless plating with simplified pretreatment and powder metallurgy. The phase and morphology of W–Cu/TiN composite powders and sintered W–Cu/TiN samples were characterized via X-ray diffraction and field emission scanning electron microscopy. Transmission electron microscopy was performed to characterize the microstructure of the sintered W–Cu/TiN samples. The relative density, hardness, electrical conductivity, and compressive strength of the sintered samples were examined. Results showed that W–30Cu composite powders with a uniform structure can be obtained using W powder pretreated with nitric acid, ammonium fluoride, and hydrofluoric acid followed by electroless Cu plating. The addition of TiN nanoparticles significantly affected the microstructure and properties of the W–30Cu composites. A good combination of the compressive strength and hardness of the W–30Cu composite material can be obtained by incorporating the TiN additive at 0.25 wt.%. However, the relative density and electrical conductivity slightly decreased

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

Directory of Open Access Journals (Sweden)

Giti Javan

2006-02-01

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

Comparing the Air Abrasion Cutting Efficacy of Dentine Using a Fluoride-Containing Bioactive Glass versus an Alumina Abrasive: An In Vitro Study

Directory of Open Access Journals (Sweden)

Melissa H. X. Tan

2015-01-01

Full Text Available Air abrasion as a caries removal technique is less aggressive than conventional techniques and is compatible for use with adhesive restorative materials. Alumina, while being currently the most common abrasive used for cutting, has controversial health and safety issues and no remineralisation properties. The alternative, a bioactive glass, 45S5, has the advantage of promoting hard tissue remineralisation. However, 45S5 is slow as a cutting abrasive and lacks fluoride in its formulation. The aim of this study was to compare the cutting efficacy of dentine using a customised fluoride-containing bioactive glass Na0SR (38–80 μm versus the conventional alumina abrasive (29 μm in an air abrasion set-up. Fluoride was incorporated into Na0SR to enhance its remineralisation properties while strontium was included to increase its radiopacity. Powder outflow rate was recorded prior to the cutting tests. Principal air abrasion cutting tests were carried out on pristine ivory dentine. The abrasion depths were quantified and compared using X-ray microtomography. Na0SR was found to create deeper cavities than alumina (p<0.05 despite its lower powder outflow rate and predictably reduced hardness. The sharper edges of the Na0SR glass particles might improve the cutting efficiency. In conclusion, Na0SR was more efficacious than alumina for air abrasion cutting of dentine.

Physicochemical characterization of point defects in fluorine doped tin oxide films

Science.gov (United States)

Akkad, Fikry El; Joseph, Sudeep

2012-07-01

The physical and chemical properties of spray deposited FTO films are studied using FESEM, x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), electrical and optical measurements. The results of XRD measurements showed that the films are polycrystalline (grain size 20-50 nm) with Rutile structure and mixed preferred orientation along the (200) and (110) planes. An angular shift of the XRD peaks after F-doping is observed and interpreted as being due to the formation of substitutional fluorine defects (FO) in presence of high concentration of oxygen vacancies (VO) that are electrically neutral. The electrical neutrality of oxygen vacancies is supported by the observation that the electron concentration n is two orders of magnitude lower than the VO concentration calculated from chemical analyses using XPS measurements. It is shown that an agreement between XPS, XRD, and Hall effect results is possible provided that the degree of deviation from stoichiometry is calculated with the assumption that the major part of the bulk carbon content is involved in O-C bonds. High temperature thermal annealing is found to cause an increase in the FO concentration and a decrease in both n and VO concentrations with the increase of the annealing temperature. These results could be interpreted in terms of a high temperature chemical exchange reaction between the SnO2 matrix and a precipitated fluoride phase. In this reaction, fluorine is released to the matrix and Sn is trapped by the fluoride phase, thus creating substitutional fluorine FO and tin vacancy VSn defects. The enthalpy of this reaction is determined to be approximately 2.4 eV while the energy of formation of a VSn through the migration of SnSn host atom to the fluoride phase is approximately 0.45 eV.

Cyclic voltammetric study of tin hexacyanoferrate for aqueous battery applications

Directory of Open Access Journals (Sweden)

Denys Gromadskyi

2016-09-01

Full Text Available A hybrid composite containing 65 mass % of tin hexacyanoferrate mixed with 35 mass % of carbon nanotubes has been synthesized and its electrochemical behavior as a negative electrode in alkali metal-ion batteries has been studied in 1 mol L-1 aqueous solution of sodium sulfate. The specific capacity of pure tin hexacyanoferrate is 58 mAh g-1, whereas the specific capacity normalized per total electrode mass of the composite studied reaches 34 mAh g-1. The estimated maximal specific power of an aqueous alkali-metal ion battery with a tin hexacyanoferrate electrode is ca. 3.6 kW kg-1 being comparable to characteristics of industrial electric double-layer capacitors. The maximal specific energy accumulated by this battery may reach 25.6 Wh kg-1 at least three times exceeding the specific energy for supercapacitors.

Metabolomic Effects of Xylitol and Fluoride on Plaque Biofilm in Vivo

OpenAIRE

Takahashi, N.; Washio, J.

2011-01-01

Dental caries is initiated by demineralization of the tooth surface through acid production from sugar by plaque biofilm. Fluoride and xylitol have been used worldwide as caries-preventive reagents, based on in vitro-proven inhibitory mechanisms on bacterial acid production. We attempted to confirm the inhibitory mechanisms of fluoride and xylitol in vivo by performing metabolome analysis on the central carbon metabolism in supragingival plaque using the combination of capillary electrophores...

NMR as a tool for kinetic studies: application to the assessment of organo tin reactivity

Energy Technology Data Exchange (ETDEWEB)

Fouquet, E.; Roulet, T. [Bordeaux-1 Univ., 33 - Talence (France); Pianet, I. [Bordeaux-1 Univ., 33 -Talence (France) CNRS, Centre d`Etudes Structurales et d`Analyse des Molecules Organiques; Willem, R. [Brussels University (VUB), Brussels (Belgium)

1998-02-01

There is a growing interest for the research of an answer to the environmental problems related to the industrial use of tetra organo tins. An interesting alternative would be to develop the chemistry of mono organo tins because of their lower toxicity and of the easy removal of ``inorganic`` tin side products. In this work, halogen exchange rates are measured for various mono organo tins with NMR techniques (EXSY spectra and 1 D {sup 119} Sn NMR), and an exchange mechanism is proposed. A correlation between kinetic data and the reactivity of the mono organo tins is then exemplified with radical allylic transfer and palladium catalyzed coupling reactions. (authors) 14 refs.

Antimicrobial activity of fluoride and its in vivo importance: identification of research questions.

Science.gov (United States)

Van Loveren, C

2001-01-01

This manuscript discusses the antimicrobial activity of fluoride and its in vivo importance in order to identify research questions. There is a lot of information on mechanisms by which fluoride may interfere with bacterial metabolism and dental plaque acidogenicity. The antimicrobial activity of fluoride products is enhanced when fluoride is associated with antimicrobial cations like Sn(2+) and amine. It is not clear whether the antimicrobial mechanisms of fluoride are operating in vivo or even to what extent antimicrobial activity can contribute to caries prevention. This latter question may be the most important one in research. Copyright 2001 S. Karger AG, Basel.

Hydrothermal synthesis and formation mechanism of hexagonal yttrium hydroxide fluoride nanobundles

International Nuclear Information System (INIS)

Tian, Li; Sun, QiLiang; Zhao, RuiNi; He, HuiLin; Xue, JianRong; Lin, Jun

2013-01-01

Graphical abstract: The formation of yttrium hydroxide fluorides nanobundles can be expressed as a precipitation transformation from cubic NaYF 4 to hexagonal NaYF 4 and to hexagonal Y(OH) 2.02 F 0.98 owing to ion exchange. - Highlights: • Novel Y(OH) 2.02 F 0.98 nanobundles have been successfully prepared by hydrothermal method. • The branched nanobundles composed of numerous oriented-attached nanoparticles has been studied. • The growth mechanism is proposed to be ion exchange and precipitation transformation. - Abstract: This article presents the fabrication of hexagonal yttrium hydroxide fluoride nanobundles via one-pot hydrothermal process, using yttrium nitrate, sodium hydroxide and ammonia fluoride as raw materials to react in propanetriol solvent. The X-ray diffraction pattern clearly reveals that the grown product is pure yttrium hydroxide fluoride, namely Y(OH) 2.02 F 0.98 . The morphology and microstructure of the synthesized product is testified to be nanobundles composed of numerous oriented-attached nanoparticles as observed from the field emission scanning electron microscopy (FESEM). The chemical composition was analyzed by the energy dispersive spectrum (EDS), confirming the phase transformation of the products which was clearly consistent with the result of XRD analysis. It is proposed that the growth of yttrium hydroxide fluoride nanobundles be attributed to ion exchange and precipitation transformation

Reactivation of a Tin-Oxide-Containing Catalyst

Science.gov (United States)

Hess, Robert; Sidney, Barry; Schryer, David; Miller, Irvin; Miller, George; Upchurch, Bill; Davis, Patricia; Brown, Kenneth

2010-01-01

The electrons in electric-discharge CO2 lasers cause dissociation of some CO2 into O2 and CO, and attach themselves to electronegative molecules such as O2, forming negative O2 ions, as well as larger negative ion clusters by collisions with CO or other molecules. The decrease in CO2 concentration due to dissociation into CO and O2 will reduce the average repetitively pulsed or continuous wave laser power, even if no disruptive negative ion instabilities occur. Accordingly, it is the primary object of this invention to extend the lifetime of a catalyst used to combine the CO and O2 products formed in a laser discharge. A promising low-temperature catalyst for combining CO and O2 is platinum on tin oxide (Pt/SnO2). First, the catalyst is pretreated by a standard procedure. The pretreatment is considered complete when no measurable quantity of CO2 is given off by the catalyst. After this standard pretreatment, the catalyst is ready for its low-temperature use in the sealed, high-energy, pulsed CO2 laser. However, after about 3,000 minutes of operation, the activity of the catalyst begins to slowly diminish. When the catalyst experiences diminished activity during exposure to the circulating gas stream inside or external to the laser, the heated zone surrounding the catalyst is raised to a temperature between 100 and 400 C. A temperature of 225 C was experimentally found to provide an adequate temperature for reactivation. During this period, the catalyst is still exposed to the circulating gas inside or external to the laser. This constant heating and exposing the catalyst to the laser gas mixture is maintained for an hour. After heating and exposing for an appropriate amount of time, the heated zone around the catalyst is allowed to return to the nominal operating temperature of the CO2 laser. This temperature normally resides in the range of 23 to 100 C. Catalyst activity can be measured as the percentage conversion of CO to CO2. In the specific embodiment

Fluoride glass fiber optics

CERN Document Server

Aggarwal, Ishwar D

1991-01-01

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

Fabrication of dense panels in lithium fluoride

International Nuclear Information System (INIS)

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

1958-04-01

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

Fluoride metabolism in plants

Energy Technology Data Exchange (ETDEWEB)

Peters, R; Shorthouse, M

1964-04-04

Grass seedlings exposed to inorganic fluoride solutions do not take up appreciable amounts of fluoride until concentrations of more than 1.0 mM (19 p.p.m.) are used. No formation of organic fluoride has been found, even with exposure to 15.75 mM fluoride, indicating that there is no formation of fluoroacetate or similar compounds. 8 references, 2 tables.

Bottled Water and Fluoride

Science.gov (United States)

... Private Wells Infant Formula Fluorosis Public Health Service Recommendation Water Operators & Engineers Water Fluoridation Additives Shortages of Fluoridation Additives Drinking Water Pipe Systems CDC-Sponsored Water Fluoridation Training Links to Other ...

Chemistry of tin compounds and environment

International Nuclear Information System (INIS)

Ali, S.; Mazhar, M.; Mahmood, S.; Bhatti, M.H.; Chaudhary, M.A.

1997-01-01

Of the large volume of tin compounds reported in the literature, possible only 100 are commercially important. Tin compounds are a wide variety of purposes such as catalysts, stabilizers for many materials including polymer, biocidal agents, bactericides, insecticides, fungicides, wood preservatives, acaricides and anti fouling agents in paints, anticancer and antitumour agents, ceramic opacifiers, as textile additives, in metal finishing operations, as food additives and in electro conductive coating. All these applications make the environment much exposed to tin contamination. The application of organotin compounds as biocides account for about 30% of total tin consumption suggesting that the main environmental effects are likely to originate from this sector. Diorgano tins and mono-organo tins are used mainly in plastic industry which is the next big source for environmental pollution. In this presentation all environmental aspects of the use of tin compounds and the recommended preventive measures are discussed. (author)

The Effects of Remineralization via Fluoride Versus Low-Level Laser IR810 and Fluoride Agents on the Mineralization and Microhardness of Bovine Dental Enamel

Directory of Open Access Journals (Sweden)

Edith Lara-Carrillo

2018-01-01

Full Text Available The objective of this study was to assess the mineralization and microhardness of bovine dental enamel surfaces treated with fluoride, tri-calcium phosphate, and infrared (IR 810 laser irradiation. The study used 210 bovine incisors, which were divided into six groups (n = 35 in each: Group A: Untreated (control, Group B: Fluoride (Durapath-Colgate, Group C: Fluoride+Tri-calcium phosphate (Clin-Pro White-3 M, Group D: Laser IR 810 (Quantum, Group E: Fluoride+laser, and Group F: Fluoride+tri-calcium phosphate+laser. Mineralization was measured via UV-Vis spectroscopy for phosphorus and via atomic absorption spectroscopy for calcium upon demineralization and remineralization with proven agents. Microhardness (SMH was measured after enamel remineralization. Mineral loss data showed differences between the groups before and after the mineralizing agents were placed (p < 0.05. Fluoride presented the highest remineralization tendency for both calcium and phosphate, with a Vickers microhardness of 329.8 HV0.1/11 (p < 0.05. It was observed that, if remineralization solution contained fewer minerals, the microhardness surface values were higher (r = −0.268 and −0.208; p < 0.05. This study shows that fluoride has a remineralizing effect compared with calcium triphosphate and laser IR810. This in vitro study imitated the application of different remineralizing agents and showed which one was the most efficient for treating non-cavitated injuries. This can prevent the progression of lesions in patients with white spot lesions.

XRF measurements of tin, copper and zinc in antifouling paints coated on leisure boats

International Nuclear Information System (INIS)

Ytreberg, Erik; Bighiu, Maria Alexandra; Lundgren, Lennart; Eklund, Britta

2016-01-01

Tributyltin (TBT) and other organotin compounds have been restricted for use on leisure boats since 1989 in the EU. Nonetheless, release of TBT is observed from leisure boats during hull maintenance work, such as pressure hosing. In this work, we used a handheld X-ray Fluorescence analyser (XRF) calibrated for antifouling paint matrixes to measure tin, copper and zinc in antifouling paints coated on leisure boats in Sweden. Our results show that over 10% of the leisure boats (n = 686) contain >400 μg/cm 2 of tin in their antifouling coatings. For comparison, one layer (40 μm dry film) of a TBT-paint equals ≈ 800 μg Sn/cm 2 . To our knowledge, tin has never been used in other forms than organotin (OT) in antifouling paints. Thus, even though the XRF analysis does not provide any information on the speciation of tin, the high concentrations indicate that these leisure boats still have OT coatings present on their hull. On several leisure boats we performed additional XRF measurements by progressively scraping off the top coatings and analysing each underlying layer. The XRF data show that when tin is detected, it is most likely present in coatings close to the hull with several layers of other coatings on top. Thus, leaching of OT compounds from the hull into the water is presumed to be negligible. The risk for environmental impacts arises during maintenance work such as scraping, blasting and high pressure hosing activities. The data also show that many boat owners apply excessive paint layers when following paint manufacturers recommendations. Moreover, high loads of copper were detected even on boats sailing in freshwater, despite the more than 20 year old ban, which poses an environmental risk that has not been addressed until now. - Highlights: • A new XRF application for analysing metals in antifouling paints has been used. • Almost 700 leisure boats were analysed for tin, copper and zinc. • Over 10% of the leisure boats contained high, >400�

Organoboron compounds as Lewis acid receptors of fluoride ions in polymeric membranes.

Science.gov (United States)

Jańczyk, Martyna; Adamczyk-Woźniak, Agnieszka; Sporzyński, Andrzej; Wróblewski, Wojciech

2012-07-06

Newly synthesized organoboron compounds - 4-octyloxyphenylboronic acid (OPBA) and pinacol ester of 2,4,6-trifluorophenylboronic acid (PE-PBA) - were applied as Lewis acid receptors of fluoride anions. Despite enhanced selectivity, the polymer membrane electrodes containing the lipophilic receptor OPBA exhibited non-Nernstian slopes of the responses toward fluoride ions in acidic conditions. Such behavior was explained by the lability of the B-O bond in the boronic acids, and the OH(-)/F(-) exchange at higher fluoride content in the sample solution. In consequence, the stoichiometry of the OPBA-fluoride complexes in the membrane could vary during the calibration, changing the equilibrium concentration of the primary anion in membrane and providing super-Nernstian responses. The proposed mechanism was supported by (19)F NMR studies, which indicated that the fluoride complexation proceeds more effectively in acidic solution leading mainly to PhBF(3)(-) species. Finally, the performances of the membranes based on the phenylboronic acid pinacol ester, with a more stable B-O bond, were tested. As it was expected, Nernstian fluoride responses were recorded for such membranes with worsened fluoride selectivity. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesising highly reactive tin oxide using Tin(II2- ethylhexanoate polynucleation as precursor

Directory of Open Access Journals (Sweden)

Alejandra Montenegro Hernández

2009-01-01

Full Text Available Tin oxide is a widely used compound in technological applications, particularity as a catalyst, gas sensor and in making varistors, transparent conductors, electrocatalytic electrodes and photovoltaic cells. An ethylhexanoate tin salt, a carboxylic acid and poly-esterification were used for synthesising highly reactive tin oxide in the present study. Synthesis was controlled by Fourier transform infrared (FTIR spectroscopy and recording changes in viscosity. The tin oxide characteristics so obtained were determined using FTIR spectroscopy, X-ray diffraction (XRD and scanning electron microscopy (SEM. The SnO2 dust synthesised and heat-treated at 550°C yielded high density aggregates, having greater than 50 μm particle size. This result demonstrates the high reactivity of the ceramic powders synthesised here.

Preparation of rare earth fluorides from apatite concentrate

International Nuclear Information System (INIS)

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

1980-01-01

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

The Impact of Selected Fluoridated Toothpastes on Dental Erosion in Profilometric Measurement.

Science.gov (United States)

Fita, Katarzyna; Kaczmarek, Urszula

2016-01-01

Some fluoridated toothpastes, available commercially, are described to have a protective effect against dental erosion. To evaluate the influence of the selected marketed toothpastes on the human enamel exposed to acid beverages. Enamel specimens from extracted human teeth were prepared (n = 40). Specimens were randomly divided into 10 experimental groups, 4 specimens each, which were subjected to acid challenge for 10 min using orange juice (pH 3.79) or Pepsi Cola (pH 2.58) and then immersed for 2 min into a slurry of five marketed toothpastes with distilled water (1 : 3 w/w). The tested toothpastes contained 1450 or 5000 ppm fluoride, CPP-ACP with 900 ppm fluoride, 1450 ppm fluoride with potassium nitrate 5%, all of them as sodium fluoride, and 700 ppm fluoride as amine and sodium fluoride with 3500 ppm SnCl2. Enamel roughness (Ra parameter) by contact profilometer at baseline and after exposure onto soft drinks and slurry was measured. Exposure to both beverages caused a similar increase of enamel surface roughness. After the specimens immersion into slurries of toothpastes with 1450 or 5000 ppm fluoride, 1450 ppm fluoride with potassium nitrate 5% and CPP-ACP with 900 ppm fluoride the significant decrease of Ra values were found, reaching the baseline values. However, toothpaste with 700 ppm fluoride and 3500 ppm SnCl2 did not cause any fall in Ra value, probably due to other mechanism of action. Within the limitation of the study we can conclude that the sodium fluoride toothpastes are able to restore the surface profile of enamel exposed shortly to acidic soft drinks.

Development of technology and equipment for manufacturing fluorides rare-earths via non-aqueous method

International Nuclear Information System (INIS)

Chatalov, V.V.; Kozlov, O.I.; Machirev, V.P.; Zvonarev, E.N.

1998-01-01

Full text: The works on technology and equipment for rare earths (RE) fluorides are very scarce. Presently RE-fluorides are manufactured by various methods. Conventionally they can be divided into two main groups. The first group comprises methods based on precipitation of fluorides from soluble salts of corresponding metals by fluohydric acid (aqueous methods) with following thermal decomposition of aquatic fluorides obtained until anhydric state is reached. The second group (called dry, gaseous or non-aqueous) comprises methods based on direct fluorizating (by fluorine hydride, fluor or other fluorating agents) have several important advantages compared to the aqueous methods: the fluorides obtained are anhydrous; the operations of fluoride precipitation, washing, decantation, filtration are excluded as well as their drying and calcination. The process of calcination is, as a rule, accompanied by pyrohydrolysis. The products manufactured by precipitation are inferior to those obtained by the non-aqueous technique. The world production practice uses both groups of methods. Nevertheless, the method of gaseous hydrofluorination is preferable. In all non-aqueous processes the initial materials are oxides RE which interact with gaseous fluorine hydride. The initial materials - oxides are obtained by thermal decomposition of carbonates, hydroxides, oxalates and so on. One of the best type of apparatus for thermal decomposition processes is a horizontal ring shaped vibrating apparatus with direct heating. The RE - fluorides is synthesized by way of RE-oxide interacting with hydrogen fluoride at 200-550 deg C in single continuous operation: (RE) 2 O 3 + 6 HF → 2 (RE)F 3 + 3 H 2 0 The apparatus consists of a nickel horizontal two tube screw. Reaction time is varied from 2 to 6 hours; the productivity of reactor is defined by feed screw rotation and initial material bulk density. Hydrogen fluoride was passing the reactor opposite to the solid phase. The degree

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

Science.gov (United States)

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

2002-10-01

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

Probing ge distribution in zeolite frameworks by post-synthesis introduction of fluoride in as-made materials

KAUST Repository

Liu, Xiaolong; Ravon, Ugo; Bosselet, Franç oise; Bergeret, Gé rard; Tuel, Alain

2012-01-01

A new method has been developed to introduce fluoride in the structure of as-made germanium-containing zeolites prepared under pure alkaline media. Incorporation of fluoride species occurs without modification of the framework composition (Si

X-ray radiometric separation of low-grade tin ores

Energy Technology Data Exchange (ETDEWEB)

Kotler, N.I.; Neverov, A.D.; Konovalov, V.M.; Mironov, I.I.; Zakharov, S.N.

1984-10-01

The investigations on evaluation of X-ray radiometric separation of off-grade tin ores of one of the deposits are carried out. The experiments have been performed at loboratory and pilot-commerical plants. /sup 241/Am has been used as a radiation source. In the course of facility commercial the ore has been separated by means of a device comprising a separator and gate separatin device. The results of X-ray radiometric separation have shown its high productive efficiency. Concentrates with higher tin content at high extraction from ores are obtained.

X-ray radiometric separation of low-grade tin ores

International Nuclear Information System (INIS)

Kotler, N.I.; Neverov, A.D.; Konovalov, V.M.; Mironov, I.I.; Zakharov, S.N.

1984-01-01

The investigations on evaluation of X-ray radiometric separation of off-grade tin ores of one of the deposits are carried out. The experiments have been performed at loboratory and pilot-commerical plants. 241 Am has been used as a radiation source. In the course of facility commercial the ore has been separated by means of a device comprising a separator and gate separatin device. The results of X-ray radiometric separation have shown its high productive efficiency. Concentrates with higher tin content at high extraction from ores are obtained

Accelerated synthesis of Sn-BEA in fluoride media

DEFF Research Database (Denmark)

Yakimov, Alexander V.; Kolyagin, Yury G.; Tolborg, Søren

2016-01-01

, for which y was fixed to 5.6, 6.8 and 7.7 at x = 0.005 and to 5.6 and 6.8 at x = 0.010. The crystallization time was varied within 0.5 – 60 days. The intermediate and final products obtained were investigated using XRD, FTIR, XRF, SEM, UV-Vis, MAS NMR spectroscopy and nitrogen adsorption......Tin-containing zeotypes, particularly Sn-BEA, are promising heterogeneous catalysts for a number of important industrially relevant reactions. However, the direct hydrothermal synthesis of these materials requires unfavourably long times, which is an obstacle for their industrial application......-desorption techniques. The products obtained with lower water content are shown to have the same structure, textural properties and morphology as materials synthesized with higher water content. Although the size of the crystals is found to decrease with water content in the gel, it does not affect the Sn coordination...

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

KAUST Repository

Drouiche, Nadjib; Aoudj, Salaheddine; Lounici, Hakim; Mahmoudi, Hacè ne; Ghaffour, NorEddine; Goosen, Mattheus F A

2011-01-01

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

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

KAUST Repository

Drouiche, Nadjib

2011-05-01

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

Tin Dioxide as an Effective Antioxidant for Proton Exchange Membrane Fuel Cells

DEFF Research Database (Denmark)

Andersen, Shuang Ma; Nørgaard, Casper Frydendal; Larsen, Mikkel Juul

2015-01-01

Tin dioxide (SnO2) containing electrodes showed significantly lower radical induced polymer degradation under single cell open circuit voltage (OCV) treatment than SnO2 free electrodes. A backbone related segment was detected under 100%RH, and an oxygen containing side chain segment was detected ...

Sources and historical record of tin and butyl-tin species in a Mediterranean bay (Toulon Bay, France).

Science.gov (United States)

Pougnet, Frédérique; Schäfer, Jörg; Dutruch, Lionel; Garnier, Cédric; Tessier, Erwan; Dang, Duc Huy; Lanceleur, Laurent; Mullot, Jean-Ulrich; Lenoble, Véronique; Blanc, Gérard

2014-05-01

Concentrations of inorganic tin (Sn(inorg)), tributyltin (TBT) and its degradation products dibutyltin (DBT) and monobutyltin (MBT) were measured in surface sediments and in two cores from the Toulon Bay, hosting the major French military harbour. Anticipating planned dredging, the aim of the present work is to map and evaluate for the first time the recent and historic contamination of these sediments by inorganic and organic Sn species derived from antifouling paints used for various naval domains including military, trade, tourism and leisure. Tin and butyl-Sn concentrations in the bay varied strongly (4 orders of magnitude), depending on the site, showing maximum values near the shipyards. The concentrations of total Sn (1.3-112 μg g(-1)), TBT (product Sn(inorgBT) is by far the dominant species after 10-12 half-life periods and (c) using recent data to reliably assess former TBT contamination requires the use of a modified butyl-Sn degradation index BDI(mod). Resuspension of extremely contaminated subsurface sediments by the scheduled dredging will probably result in mobilization of important amounts of butyl-Sn species.

Bismuth-, Tin-, and Lead-Containing Metal-Organic Materials: Synthesis, Structure, Photoluminescence, Second Harmonic Generation, and Ferroelectric Properties

Science.gov (United States)

Wibowo, Arief Cahyo

Metal-Organic Materials (MOMs) contain metal moieties and organic ligands that combine to form discrete (e.g. metal-organic polyhedra, spheres or nanoballs, metal-organic polygons) or polymeric structures with one-, two-, or three-dimensional periodicities that can exhibit a variety of properties resulting from the presence of the metal moieties and/or ligand connectors in the structure. To date, MOMs with a range of functional attributes have been prepared, including record-breaking porosity, catalytic properties, molecular magnetism, chemical separations and sensing ability, luminescence and NLO properties, multiferroic, ferroelectric, and switchable molecular dielectric properties. We are interested in synthesizing non-centrosymmetric MOM single crystals possessing one of the ten polar space groups required for non-linear optical properties (such as second harmonic generation) and ferroelectric applications. This thesis is divided into two main parts: materials with optical properties, such as photoluminescence and materials for targeted applications such as second harmonic generation and ferroelectric properties. This thesis starts with an introduction describing material having centrosymmetric, non-polar space groups, single crystals structures and their photoluminescence properties. These crystals exhibit very interesting and rare structures as well as interesting photoluminescence properties. Chapters 2-5 of this thesis focus on photoluminescent properties of new MOMs, and detail the exploratory research involving the comparatively rare bismuth, lead, and tin coordination polymers. Specifically, the formation of single white-light emitting phosphors based on the combination of bismuth or lead with pyridine-2,5-dicarboxylate is discussed (Chapter 2). The observation of a new Bi2O2 layer and a new Bi4O 3 chain in bismuth terephthalate-based coordination polymers is presented in Chapter 3, while the formation of diverse structures of tin-based coordination

In vitro assessment of 3 dentifrices containing fluoride in preventing demineralization of overdenture abutments and root surfaces.

Science.gov (United States)

Goettsche, Zachary S; Ettinger, Ronald L; Wefel, James S; Hogan, Mary M; Harless, Jeffery D; Qian, Fang

2014-11-01

Caries development under overdentures has been a continuing problem and requires the daily use of fluoride to prevent demineralization. The purpose of this in vitro study was to compare the effectiveness of dentifrices containing tricalcium phosphate or calcium phosphosilicate in combination with fluoride to prevent the demineralization of overdenture abutments and root surfaces. A total of 56 caries-free extracted teeth were prepared as overdenture abutments. The teeth were painted with acid-resistant varnish, leaving one 1×4-mm window on occlusal and root surfaces. The teeth were randomly divided into 4 groups: a control group treated with distilled/deionized water only, a group treated with ClinPro 5000, a group treated with ReNew, and a group treated with Prevident 5000 gel. Each tooth was subjected to a demineralizing/remineralizing cycling protocol for 12 days with the appropriate treatment products. The teeth were sectioned longitudinally through both windows. Photomicrographs were made of 3 representative sections from each tooth. A representative section was defined as one that included both windows and was cut from the part of the tooth that had the flattest surface to reduce the edge effect. The depths of the lesions were measured on representative sections from each group. A 1-way MANOVA and a 1-way ANOVA with the post hoc Tukey-Kramer test were used to evaluate the treatment effects on the criterion variables (α=.05). The total lesion depths of the control teeth on the occlusal surface were not statistically significantly deeper than for the 3 dentifrices (P=.7705). However, all 3 dentifrices had narrower cavitation depths than the control (mean cavitation band depth, 43.59 [ReNew] versus 37.99 [Prevident 5000 gel] versus 36.70 [ClinPro 5000] versus 246.86 [control]) (Pteeth treated with Prevident 5000 gel had the shallowest total lesion depth and were statistically significantly different from those treated with ReNew and Clin

Low-temperature Synthesis of Tin(II) Oxide From Tin(II) ketoacidoximate Precursor

KAUST Repository

Alshankiti, Buthainah

2015-01-01

Sn (II) oxide finds numerous applications in different fields such as thin film transistors1, solar cells2 and sensors.3 In this study we present the fabrication of tin monoxide SnO by using Sn (II) ketoacid oximate complexes as precursors. Tin (II

Tin (II Chloride Catalyzed Esterification of High FFA Jatropha Oil: Experimental and Kinetics Study

Directory of Open Access Journals (Sweden)

Ratna Dewi Kusumaningtyas

2014-05-01

Full Text Available Biodiesel is one of the promising energy source alternatives to fossil fuel. To produce biodiesel in a more economical way, the employment of the low-cost feed stocks, such as non-edible oils with high free fatty acid (FFA, is necessary. Accordingly, the esterification reaction of FFA in vegetable oils plays an important role in the biodiesel production. In this work, esterification of FFA contained in Crude Jatropha Oil (CJO in the presence of tin (II chloride catalyst in a batch reactor has been carried out. The esterification reaction was conducted using methanol at the temperature of 40-60 °C for 4 hours. The effect of molar ratio of methanol to oil was studied in the range 15:1 to 120:1. The influence of catalyst loading was investigated in the range of 2.5 to 15% w/w oil. The optimum reaction conversion was obtained at 60 °C with the catalyst loading of 10% w/w oil and molar ratio of methanol to oil of 120:1. A pseudo-homogeneous reversible second order kinetic model for describing the esterification of FFA contained in CJO with methanol over tin (II chloride catalyst was developed based on the experimental data. The kinetic model can fit the data very well.

Evaluation of the Content of Lead, Cadmium, Mercury, Arsenic, Tin, Copper and Zinc during the Production Process Flow of Tomato Broth

Directory of Open Access Journals (Sweden)

Corina Andrei

2013-11-01

Full Text Available Heavy metals are among the largest contaminants of food products. Once metals are present in vegetables, their concentrations are rarely modified by industrial processing techniques, although in some cases washing may decrease the metal content. The main objective of this study was to quantify the effect of industrial processing on the content of lead, cadmium, mercury, arsenic, tin, copper and zinc in tomatoes and products resulting on flow technology of tomato broth. For the determination of essential elements and/or potentially toxic was use atomic absorption spectrometry. The analytical results for quantitative evaluation the concentrations of the investigated elements on the samples of tomatoes taken from the technological process of the production of tomato broth indicated the presence of Pb, Cd, Cu and Zn but with a level of concentration that significantly decreased in the finished product and the absence of metals Hg and As in all investigated samples. Effect of industrial processing on the content of tin in tomato samples analyzed was characterized by fluctuations in the residual content that led to a significant increase in concentration of 0.100 ± 0.041 mg kg-1 (tomatoes - unprocessed to 0.200 ± 0.041 mg kg-1 (tomato broth.

Water Fluoridation Statistics - Percent of PWS population receiving fluoridated water

Data.gov (United States)

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

Water Fluoridation Statistics - Percent of PWS population receiving fluoridated water

Data.gov (United States)

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

Pretreatment of Platinum/Tin Oxide-Catalyst

Science.gov (United States)

Hess, Robert V.; Paulin, Patricia A.; Miller, Irvin M.; Schryer, David R.; Sidney, Barry D.; Wood, George M.; Upchurch, Billy T.; Brown, Kenneth G.

1987-01-01

Addition of CO to He pretreatment doubles catalytic activity. In sealed, high-energy, pulsed CO2 laser, CO and O2 form as decomposition products of CO2 in laser discharge zone. Products must be recombined, because oxygen concentration of more than few tenths of percent causes rapid deterioration of power, ending in unstable operation. Promising low-temperature catalyst for combining CO and O2 is platinum on tin oxide. New development increases activity of catalyst so less needed for recombination process.

FDA Peanut-Containing Product Recall

Data.gov (United States)

U.S. Department of Health & Human Services — The FDA Peanut-Containing Product Recall widget allows you to browse the Food and Drug Administration (FDA) database of peanut butter and peanut-containing products...

The cariostatic mechanisms of fluoride

OpenAIRE

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

2013-01-01

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

Small molecule fluoride toxicity agonists.

Science.gov (United States)

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fluoride varnishes and enamel caries

NARCIS (Netherlands)

Bruyn, Hugo de

1987-01-01

Topical fluoride applications have the aim of increasing the fluoride uptake in enamel and consequently reducing caries. In the early ‘60s fluoride varnishes were introduced because they had a long contact period with the enamel which resulted in a higher fluoride uptake than from other topical

Development of rubidium and niobium containing plastic foams. Final report

International Nuclear Information System (INIS)

Botham, R.A.; McClung, C.E.; Schwendeman, J.I.

1978-01-01

Rubidium fluoride and niobium metal-containing foam samples (rods and sheets) were prepared using two foam sytems: (1) hydrophilic polyurethanes prepared from W.R. Grace Co.'s Hypol prepolymers and (2) polyimides prepared from Monsanto Company's Skybond polyimide resin. The first system was used only for preparation of rubidium fluoride-containing foams while the second was used for both rubidium fluoride and niobium-containing foams. The niobium metal could readily be incorporated into the polyimide foam during molding, to produce foam sheets of the required dimensions and density. The rubidium fluoride-containing polyimide foams were preferably prepared by first rendering the molded polyimide foam hydrophilic with a postcuring treatment, then absorbing the rubidium fluoride from water solution. Similarly, rubidium fluoride was absorbed into the hydrophilic polyurethanes from water solution. Since the high reactive rubidium metal could not be employed, rubidium fluoride, which is very hygroscopic, was used instead, primarily because of its high rubidium content (approximately 82 weight percent). This was important in view of the low total densities and the high weight percentage rubidium required in the foam samples. In addition, at the later request of LLL, a block of rigid Hypol hydrophilic polyurethane foam (with a density of approximately 0.04 g/cm 3 and cell sizes = or <0.2 mm) was prepared without any metal or metal compounds in it. Two shipments of foam samples, which met or closely approximated the project specifications, were submitted to LLL during the course of this project. Information on these samples is contained in Table 1. A complete description of their preparation is given in the Experimental Results and Discussion Section

Structural studies of supported tin catalysts

Science.gov (United States)

Nava, Noel; Viveros, Tomás

1999-11-01

Tin oxide was supported on aluminium oxide, titanium oxide, magnesium oxide and silicon oxide, and the resulting interactions between the components in the prepared samples and after reduction were characterized by Mössbauer spectroscopy. It was observed that in the oxide state, tin is present as SnO2 on alumina, magnesia and silica, but on titania tin occupies Ti sites in the structure. After hydrogen treatment at high temperatures, tin is reduced from Sn(4) to Sn(2) on alumina and titania; it is reduced from Sn(4) to Sn(0) on silica, and is practically not reduced on magnesia. These results reveal the degree of interaction between tin and the different supports studied.

Structural studies of supported tin catalysts

International Nuclear Information System (INIS)

Nava, Noel; Viveros, Tomas

1999-01-01

Tin oxide was supported on aluminium oxide, titanium oxide, magnesium oxide and silicon oxide, and the resulting interactions between the components in the prepared samples and after reduction were characterized by Moessbauer spectroscopy. It was observed that in the oxide state, tin is present as SnO 2 on alumina, magnesia and silica, but on titania tin occupies Ti sites in the structure. After hydrogen treatment at high temperatures, tin is reduced from Sn(4) to Sn(2) on alumina and titania; it is reduced from Sn(4) to Sn(0) on silica, and is practically not reduced on magnesia. These results reveal the degree of interaction between tin and the different supports studied

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

Directory of Open Access Journals (Sweden)

Afshin Maleki

2016-01-01

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

Preparation of uranium ingots from double fluorides

International Nuclear Information System (INIS)

Le Boulbin, E.

1967-05-01

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

Bleaching Gels Containing Calcium and Fluoride: Effect on Enamel Erosion Susceptibility

Directory of Open Access Journals (Sweden)

Alessandra B. Borges

2012-01-01

Full Text Available This in vitro study evaluated the effect of 35% hydrogen peroxide (HP bleaching gel modified or not by the addition of calcium and fluoride on enamel susceptibility to erosion. Bovine enamel samples (3 mm in diameter were divided into four groups (n=15 according to the bleaching agent: control—without bleaching (C; 35% hydrogen peroxide (HP; 35% HP with the addition of 2% calcium gluconate (HP + Ca; 35% HP with the addition of 0.6% sodium fluoride (HP + F. The bleaching gels were applied on the enamel surface for 40 min, and the specimens were subjected to erosive challenge with Sprite Zero and remineralization with artificial saliva for 5 days. Enamel wear was assessed using profilometry. The data were analyzed by ANOVA/ Tukey’s test (P<0.05. There were significant differences among the groups (P=0.009. The most enamel wear was seen for C (3.37±0.80 μm, followed by HP (2.89 ± 0.98 μm and HP + F (2.72 ± 0.64 μm. HP + Ca (2.31 ± 0.92 μm was the only group able to significantly reduce enamel erosion compared to C. The application of HP bleaching agent did not increase the enamel susceptibility to erosion. However, the addition of calcium gluconate to the HP gel resulted in reduced susceptibility of the enamel to erosion.

Flexible organic light-emitting diodes consisting of a platinum doped indium tin oxide anode

International Nuclear Information System (INIS)

Hsu, C-M; Huang, C-Y; Cheng, H-E; Wu, W-T

2009-01-01

This paper demonstrates that a flexible organic light-emitting diode (OLED) with a platinum (Pt)-doped indium tin oxide (ITO) anode could show superior electro-optical characteristics to those of a conventional device. The threshold voltage and turn-on voltage of an OLED device consisting of an aluminium/lithium fluoride/tris(8-hydroxyquinoline) aluminium/N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4, 4'-diamine/Pt-doped ITO/ITO structure were reduced by 1.2 V and 0.8 V, respectively. Current efficiency was found improved for a driving voltage of less than 6.5 V as a result of the enhanced hole-injection rate, attributed mainly to the elevated surface work function and partly reduced surface roughness of ITO by the incorporated Pt atoms in the ITO matrix.

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

Directory of Open Access Journals (Sweden)

Daniela Correia Cavalcante Souza

2010-12-01

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

Anomalous growth of whisker-like bismuth-tin extrusions from tin-enriched tin-Bi deposits

International Nuclear Information System (INIS)

Hu, C.-C.; Tsai, Y.-D.; Lin, C.-C.; Lee, G.-L.; Chen, S.-W.; Lee, T.-C.; Wen, T.-C.

2009-01-01

This article shows the first finding that the anomalous growth of Bi-Sn extrusions from tin-enriched alloys (Sn-xBi with x between 20 and 10 wt.%) can be induced by post-plating annealing in N 2 between 145 and 260 deg. C for 10 min although metal whiskers were commonly formed on the surface of pure metals or alloys of the enriched component. From SEM observations, very similar to Sn whiskers, Bi-Sn extrusions vary in size, shape, length, and diameter with changing the annealing temperature, which are highly important in regarding the potential for failure of electronic products. Annealing resulting in thermal expansion of Sn grains is believed to squeeze the Bi-Sn alloys with relatively low melting points to form whisker-like extrusions although the exact mechanism is unclear

Electrochemical migration of tin in electronics and microstructure of the dendrites

Energy Technology Data Exchange (ETDEWEB)

Minzari, Daniel, E-mail: dmin@mek.dtu.d [Section for Materials and Surface Technology, Department for Mechanical Engineering, Technical University of Denmark (Denmark); Grumsen, Flemming Bjerg; Jellesen, Morten S.; Moller, Per; Ambat, Rajan [Section for Materials and Surface Technology, Department for Mechanical Engineering, Technical University of Denmark (Denmark)

2011-05-15

Graphical abstract: The electrochemical migration of tin in electronics forms dendritic structures, consisting of a metallic tin core, which is surrounded by oxide layers having various thickness. Display Omitted Research highlights: Electrochemical migration occurs if two conductors are connected by condensed moisture. Metallic ions are dissolved and grow in a dendritic structure that short circuit the electrodes. The dendrite consists of a metallic tin core with oxide layers of various thickness surrounding. Detailed microstructure of dendrites is investigated using electron microscopy. The dendrite microstructure is heterogeneous along the growth direction. - Abstract: The macro-, micro-, and nano-scale morphology and structure of tin dendrites, formed by electrochemical migration on a surface mount ceramic chip resistor having electrodes consisting of tin with small amounts of Pb ({approx}2 wt.%) was investigated by scanning electron microscopy and transmission electron microscopy including Energy dispersive X-ray spectroscopy and electron diffraction. The tin dendrites were formed under 5 or 12 V potential bias in 10 ppm by weight NaCl electrolyte as a micro-droplet on the resistor during electrochemical migration experiments. The dendrites formed were found to have heterogeneous microstructure along the growth direction, which is attributed to unstable growth conditions inside the micro-volume of electrolyte. Selected area electron diffraction showed that the dendrites are metallic tin having sections of single crystal orientation and lead containing intermetallic particles embedded in the structure. At certain areas, the dendrite structure was found to be surrounded by an oxide crust, which is believed to be due to unstable growth conditions during the dendrite formation. The oxide layer was found to be of nanocrystalline structure, which is expected to be formed by the dehydration of the hydrated oxide originally formed in solution ex-situ in ambient air.

Ion exchange chromatography on a new form of tin dioxide for the isolation of strontium radioisotopes from fission products: an application to milk samples

International Nuclear Information System (INIS)

Stella, R.; Valentini, M.T.G.; Maggi, L.

1990-01-01

An amorphous, partially-reduced tin dioxide, having properties of an inorganic exchanger, was tested for application to fission product separations. Due to the good sorption of both strontium and barium the application of the exchanger to radiostrontium isolation from fission product mixtures is subjected to important restrictions. An application to 90 Sr determination in milk is proposed. (author)

Antidotal activity of Averrhoa carambola (Star fruit on fluoride induced toxicity in rats

Directory of Open Access Journals (Sweden)

Vasant Rupal A.

2014-06-01

Full Text Available Consumption of fluoride leads to several physiological disturbances in carbohydrate, lipid and antioxidant metabolisms. Averrhoa carambola L. fruit (Star fruit is a commonly consumed fruit in tropical countries and is an ingredient in folklore medicines. As the fruits have high polyphenolic and antioxidant contents, the present study was undertaken to investigate the potential of star fruit as a dietary supplement in attenuating the fluoride induced hyperglycemia, hypercholesterolemia and oxidative stress in laboratory rats. A four-week exposure to fluoride caused sustained hyperglycemia, hyperlipidemia and oxidative stress and, when the diet was supplemented with star fruit powder, carbohydrate, lipid and antioxidant profiles were restored significantly. It is surmised that the antihyperglycemic, antihypercholesterolemic and antioxidant activities of star fruit in fluoride exposed rats could be due to the presence of polyphenols, flavonoids, saponins, phytosterols, ascorbic acid and fibers in the fruit, which are all well known regulators of carbohydrate, lipid and antioxidant metabolisms. These findings suggest that star fruit can be used as a dietary supplement in fluoride endemic regions to contain fluoride induced hyperglycemia, hyperlipidemia and oxidative stress

Antidotal activity of Averrhoa carambola (Star fruit) on fluoride induced toxicity in rats.

Science.gov (United States)

Vasant, Rupal A; Narasimhacharya, A V R L

2014-06-01

Consumption of fluoride leads to several physiological disturbances in carbohydrate, lipid and antioxidant metabolisms. Averrhoa carambola L. fruit (Star fruit) is a commonly consumed fruit in tropical countries and is an ingredient in folklore medicines. As the fruits have high polyphenolic and antioxidant contents, the present study was undertaken to investigate the potential of star fruit as a dietary supplement in attenuating the fluoride induced hyperglycemia, hypercholesterolemia and oxidative stress in laboratory rats. A four-week exposure to fluoride caused sustained hyperglycemia, hyperlipidemia and oxidative stress and, when the diet was supplemented with star fruit powder, carbohydrate, lipid and antioxidant profiles were restored significantly. It is surmised that the antihyperglycemic, antihypercholesterolemic and antioxidant activities of star fruit in fluoride exposed rats could be due to the presence of polyphenols, flavonoids, saponins, phytosterols, ascorbic acid and fibers in the fruit, which are all well known regulators of carbohydrate, lipid and antioxidant metabolisms. These findings suggest that star fruit can be used as a dietary supplement in fluoride endemic regions to contain fluoride induced hyperglycemia, hyperlipidemia and oxidative stress.

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

International Nuclear Information System (INIS)

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

2012-01-01

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

Titanium and zirconium based wrought alloys and bulk metallic glasses for fluoride ion containing 11.5 M HNO3 medium

International Nuclear Information System (INIS)

Jayaraj, J.; Ningshen, S.; Mallika, C.; Kamachi Mudali, U.

2016-01-01

Aqueous reprocessing of plutonium-rich mixed oxide fuels require fluoride as a catalyst in boiling nitric acid for an effective dissolution of the spent fuel. The corrosion behavior of the candidate dissolver materials zircaloy-4 (Zr-4) and commercial pure titanium (CP-Ti grade 2) in boiling 11.5 M HNO 3 + 0.05 M NaF has been established. High corrosion rates were obtained for Zr- 4 and CP-Ti in nitric acid containing fluoride ions. Complexing the fluoride ions either with Al(NO 3 ) 3 or ZrO(NO 3 ) 2 aided in decreasing the corrosion rates of Zr-4 and CP-Ti. High corrosion resistance is claimed as one of the principal property of the amorphous alloy when compared to the crystalline alloy. Thus Ni 60 Nb 40 and Ni 60 Nb 30 Ta 10 amorphous ribbons were prepared and exposed in boiling 11.5 M HNO 3 and 11.5 M HNO 3 + 0.05 M NaF. In nitric acid these alloys did not show any sign of corrosion attack. XPS analysis confirmed that the passivity was due to the formation passive films of thickness ≈3 nm enriched with Nb 2 O 5 and of ≈1.5 nm enriched with both Nb 2 O 5 and Ta 2 O 5 on the respective surfaces of the ribbons. In boiling 11.5 M HNO 3 + 0.05 M NaF, severe corrosion attack was observed on Ni 60 Nb 40 ribbon, due to the instability of the oxide/metal interface. The Ni 60 Nb 30 Ta 10 amorphous ribbon exhibited corrosion resistance of at least an order of magnitude higher than that for Ni 60 Nb 40 ribbon

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

Directory of Open Access Journals (Sweden)

Dhull K

2009-03-01

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

Tin Whisker Formation — A Stress Relieve Phenomenon

Science.gov (United States)

Dittes, M.; Oberndorff, P.; Crema, P.; Su, P.

2006-02-01

With the move towards lead-free electronics also the solderable finish of electronic components' terminations are converted. While the typical finish was containing 5 % to 20 % lead (Pb) and thus was almost whisker free, lead (Pb)-free finishes such as pure tin or high tin alloys are rather prone to grow whisker. These whiskers are spontaneous protrusions that grow to a significant length of up to millimeters with a typical diameter in the range of few microns and are suspect to cause shorts in electronic assemblies. The latest details of the mechanisms are not yet understood. However it appears to be well established that the driving force for tin whisker growth is a compressive stress in the tin layer and that this stress is released by whisker formation. Besides the mechanism for whisker growth therefore the mechanism of the stress induction is of interest. The origin of that stress may have multiple sources. Among others the most important one is the volume increase within the tin layer due the formation of intermetallics at the interface to the base material. This applies to all copper based material. For base materials with a coefficient of thermal expansion (cte) significantly different from the tin finish another mechanism plays the dominant role. This is the induction of stress during thermal cycling due to the different expansion of the materials with every temperature change. Another mechanism for stress induction may be the oxidation of the finish, which also leads to a local volume increase. Based on the knowledge of stress induction various mitigation strategies can be deducted. Most common is the introduction of a diffusion barrier (e.g. Ni) in order to prevent the growth of the Cu-Sn intermetallics, the controlled growth of Cu-Sn intermetallics in order to prevent their irregularity or the introduction of a mechanical buffer material targeting at the minimisation of the cte mismatch between base and finish material. With respect to the stress

Fluoride retention by kaolin clay

DEFF Research Database (Denmark)

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

1997-01-01

To evaluate the potential effectiveness of kaolin clay liners in storage of fluoride contaminated waste, an experimental study of the sorption and desorption behaviour of fluoride in kaolin clay was conducted. The degree of fluoride sorption by kaolin was found to depend on solution p......H and available fluoride concentration with equilibrium being achieved within 24 h. A site activation process involving the uptake of fluoride was also observed at the initial stages of sorption. This behaviour was attributed to a layer expansion process of the clay during sorption. The maximum fluoride sorption...... capacity was found to be 18.3 meq/100 g at pH 6 and 8.6 meq/100 g at pH 7. A competitive Langmuir sorption isotherm where sorption is dependant on both pH and fluoride concentration is employed to characterise the experimental sorption and desorption data. The sorption and desorption isotherms revealed...

The determination, by X-ray-fluorescence spectrometry, of tin and tungsten in ores, concentrates, and residues of scheelite, wolframite, and cassiterite

International Nuclear Information System (INIS)

Balaes, A.M.E.; Jacobs, J.J.; Bray, A.R.; Kendrick, K.

1983-01-01

The method of analysis described is applicable to samples with tin and tungsten contents from 15p.p.m. to 75 per cent. For samples containing tin and tungsten in the range 2000p.p.m. to 75 per cent, the matrix variations are compensated for by the use of briquettes containing coarse river sand, the internal standard, and potassium chloride, the last of which acts as a binder, diluet, and grinding aid. For the samples containing tin and tungsten in the range 15p.p.m. to 2000p.p.m., the potassium chloride is omitted. Zinc and antimony are used as the internal standard for tungsten and tin respectively. Calibration graphs for tin and tungsten are obtained by the use of standard reference materials for cassiterite and scheelite. The precision of the analysis for tin ranges from a relative standard deviation of 0,039 at 50p.p.m. to 0,005 at 75 per cent. The values for tungsten are relatively constant at between 0,015 and 0,008 at concentrations between 50p.p.m. and 50 per cent. The lower limits of detection for tungsten and tin by the high-concentration technique of analysis are 202 and 155p.p.m. respectively, and by the low-concentration technique the corresponding limits are 4 and 2p.p.m. The overall time required for the analysis of ten samples by these techniques is approximately 3 hours. The laboratory method is detailed in an appendix

Fluoride kinetics in saliva after the use of a fluoride-containing chewing gum Cinética de flúor na saliva após o uso de uma goma de mascar fluoretada

Directory of Open Access Journals (Sweden)

Maria Francisca Thereza Borro Bijella

2005-12-01

Full Text Available There is a relationship between the use of fluoride, the reduction of dental caries and the increase of dental fluorosis. The purpose of this study was to analyze the fluoride kinetics in saliva after using the HappydentTM chewing gum, which contains 3.38 mg of fluoride as monofluorophosphate. Fifteen 7-9-year-old volunteers were instructed to chew the gum TridentTM (control and HappydentTM on different days. Total saliva was collected for 3 minutes, at 0, 3, 6, 9, 15, 30 and 45 minutes after starting chewing. Salivary fluoride was analyzed with a fluoride-specific electrode (Orion 96-09 after acid hydrolysis. The data were analyzed by two-way analysis of variance and by Tukey’s post hoc test (p Há uma relação entre o uso de fluoretos, a redução na cárie e o aumento da fluorose dentária. O objetivo deste estudo foi analisar a cinética do flúor na saliva após o uso da goma de mascar Happydent®, que contém 3,38 mg de flúor como monofluorfosfato. A saliva foi coletada de 15 voluntários entre 7 e 9 anos de idade, durante 3 minutos nos intervalos de 0, 3, 6, 9, 15, 30 e 45 minutos. Inicialmente, a coleta foi realizada com o Trident® (controle e, após 24 h, a coleta foi repetida com a goma de mascar Happydent®. O flúor foi analisado com um eletrodo íon-específico (Orion 96-09 após a realização da hidrólise ácida. Os dados foram analisados através da análise de variância a dois critérios e pelo teste de Tukey (p < 0,05. A quantidade média ± dp (mg de flúor liberado na saliva foi 0,276 ± 0,126 e 0,024 ± 0,014 para o Happydent® e o Trident®, respectivamente. A quantidade de flúor nas amostras de saliva após o uso do Happydent® foi significativamente maior do que após o uso do Trident® em todos os tempos experimentais, com exceção dos períodos de 30 e 45 minutos. A alta quantidade de flúor na saliva após o uso do Happydent® poderia ser eficiente na prevenção da cárie dentária, o que deveria ser avaliado

Discrimination of fluoride and phosphate contamination in central Florida for analyses of environmental effects

Science.gov (United States)

Coker, A. E.; Marshall, R.; Thomson, F.

1972-01-01

A study was made of the spatial registration of fluoride and phosphate pollution parameters in central Florida by utilizing remote sensing techniques. Multispectral remote sensing data were collected over the area and processed to produce multispectral recognition maps. These processed data were used to map land areas and waters containing concentrations of fluoride and phosphate. Maps showing distribution of affected and unaffected vegetation were produced. In addition, the multispectral data were processed by single band radiometric slicing to produce radiometric maps used to delineate areas of high ultraviolet radiance, which indicates high fluoride concentrations. The multispectral parameter maps and radiometric maps in combination showed distinctive patterns, which are correlated with areas known to be affected by fluoride and phosphate contamination. These remote sensing techniques have the potential for regional use to assess the environmental impact of fluoride and phosphate wastes in central Florida.

Silver aggregates and twofold-coordinated tin centers in phosphate glass: A photoluminescence study

International Nuclear Information System (INIS)

Jimenez, J.A.; Lysenko, S.; Liu, H.; Fachini, E.; Resto, O.; Cabrera, C.R.

2009-01-01

The optical properties of silver species in various oxidation and aggregation states and of tin centers in melt-quenched phosphate glasses have been assessed by optical absorption and photoluminescence (PL) spectroscopy. Glasses containing silver and tin, or either dopant, were studied. Emission and excitation spectra along with time-resolved and temperature-dependent PL measurements were employed in elucidating the different emitting centers observed and investigating on their interactions. In regard to silver, the data suggests the presence of luminescent single Ag + ions, Ag + -Ag + and Ag + -Ag 0 pairs, and nonluminescent Ag nanoparticles (NPs), where Ag + -Ag 0 →Ag + -Ag + energy transfer is indicated. Tin optical centers appear as twofold-coordinated Sn centers displaying PL around 400 nm ascribed to triplet-to-singlet electronic transitions. The optically active silver centers were observed in glasses where 8 mol% of both Ag 2 O and SnO, and 4 mol% of Ag 2 O were added. Heat treatment (HT) of the glass with the high concentration of silver and tin leads to chemical reduction of ionic silver species resulting in a large volume fraction of silver NPs and the vanishing of silver PL features. Further characterization of such heat-treated glass by transmission electron microscopy and X-ray photoelectron spectroscopy appears consistent with silver being present mainly in nonoxidized form after HT. On the other hand, HT of the glass containing only silver results in the quenching of Ag + -Ag 0 pairs emission that is ascribed to nonradiative energy transfer to Ag NPs due to the positioning of the pairs near the surface of NPs during HT. In this context, an important finding is that a faster relaxation was observed for this nanocomposite in relation to a heat-treated glass containing both silver and tin (no silver pairs) as revealed by degenerate four-wave mixing spectroscopy. Such result is attributed to Ag NP→Ag + -Ag 0 plasmon resonance energy transfer. The

Fluoride analysis

Energy Technology Data Exchange (ETDEWEB)

Brandt, C S

1963-01-01

The methods and procedures for the detection and estimation of fluoride are varied and numerous. The problems of sampling, contamination, and loss in sampling waters, plant and animal tissues and atmospheres are discussed, along with brief descriptors of methods most commonly used. Techniques for separating fluorides from matrixes are discussed, as well as gravimetric, calorimetric, and spectrophotometric analytical techniques.

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

Science.gov (United States)

Bizhang, Mozhgan; Chun, Yong-Hee P; Winterfeld, Mai-Trinh; Altenburger, Markus J; Raab, Wolfgang H M; Zimmer, Stefan

2009-07-23

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

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

Science.gov (United States)

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

2010-05-01

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

Story of Fluoridation

Science.gov (United States)

... Home Health Info Health Topics Fluoride Share The Story of Fluoridation It started as an observation, that ... this time using photospectrographic analysis, a more sophisticated technology than that used by McKay. Churchill asked an ...

Recovery of antimony-125 from tin-124 irradiated by neutrons

International Nuclear Information System (INIS)

Baluev, A.V.; Mityakhina, V.S.; Krasnikov, L.V.; Galkin, B.Ya.; Besnosyuk, V.I.

2003-01-01

Separation of 125 Sb from tin using highly basic, medium-basic, and weakly basic ion-exchangers was studied. The best results were obtained for AN-31 weakly basic anion exchanger. The yield of 125 Sb was 95 -98 % of the initial activity, the yield of tin, 98 ± 0.5% of the initial amount. The separation coefficient is 10 6 -10 7 for one cycle. A procedure based on ion exchange was developed. Extraction procedures of separation of 125 Sb from tin were studied. Isoamyl alcohol, ethyl acetate, and di-n-butyl ether were used as extracting agents. The most efficient extracting agent is di-n-butyl ether. Carrier-free radiochemically pure sample of 125 Sb was produced. More than 20 mCi of the target product was recovered. The extraction recovery procedure of 125 Sb has been developed. (author)

New transition metal oxide fluorides with ReO{sub 3}-type structure

Energy Technology Data Exchange (ETDEWEB)

Nakhal, Suliman; Lerch, Martin [Technische Universitaet Berlin (Germany). Inst. fuer Chemie

2016-08-01

The new niobium oxide fluorides MNbO{sub 2}F{sub 4} [M = (Cr, Fe)], CrNb{sub 2}O{sub 4}F{sub 5}, and Fe{sub 2}Nb{sub 3}O{sub 6}F{sub 9} were prepared by treatment of chromium or iron nitrate with Nb-containing hydrofluoric acid solutions. Crystal structures were investigated by means of X-ray powder diffraction. All new compounds can be structurally refined in the cubic ReO{sub 3}-type. The iron niobium oxide fluorides are reddish orange, and chromium containing phases exhibit a light green color. The niobium atoms are in the highest formal oxidation state.

Private Well Water and Fluoride

Science.gov (United States)

... Private Wells Infant Formula Fluorosis Public Health Service Recommendation Water Operators & Engineers Water Fluoridation Additives Shortages of Fluoridation Additives Drinking Water Pipe Systems CDC-Sponsored Water Fluoridation Training Links to Other ...

Determination of the stability constants of a number of metal fluoride complexes and their rates of formation

International Nuclear Information System (INIS)

Hammer, R.R.

1979-08-01

The stability constants of the fluoride complexes of Al +3 , H 3 BO 3 , Cr +3 , Cr +6 , Fe +3 , Gd +3 , Nb +5 , UO 2 +2 , and Zr +4 were determined in 0.96 and 2.88 M HNO 3 solutions in the temperature range 25 to 60 0 C with a fluoride specific ion electrode. These data can be used to calculate the concentration of chemical species in solution and will be used to correlate solution properties with solution composition. The solubilities of some fluoride precipitates were also measured in nitric acid solutions. The rates of formation of the fluoborates, aluminum fluoride, and zirconium fluoride complexes were measured with a fluoride specific ion electrode at 25, 35, and 45 0 C. The rates of formation of all complexes, except BF 4 - , AlF +2 , and a fluoride complex with aluminum containing more than three fluorides associated with it, were too fast to measure with the instrumentation used

IN VITRO EVALUATION OF FLUORIDE RELEASE OF JELTRATE® DENTAL ALGINATE

Directory of Open Access Journals (Sweden)

Matheus Melo Pithon

2009-04-01

Full Text Available Objective: To evaluate of fluoride release from Jeltrate alginate®. Materials and Methods: Four Trademarks of alginate were divided in four groups: conventional Jeltrate®, Plus Jeltrate®, Chromatic Jeltrate® and Chromatic Ortho Jeltrate®. The alginates were handled following the guidelines of the manufacturers. After this was followed by the construction of evidence bodies using silicone molds of the dimensions of 4 mm in diameter and 4mm in height. After take prey, the evidence bodies were removed from the molds and placed in container with 10 ml of ultra purified water, for 2 min. The fluoride release was measured by selective ion electrode connected to an analyzer of ions. Results: The Plus Jeltrate® showed a higher releasing fluoride 247.85 µg/cm2 followed by Chromatic Ortho Jeltrate® (217.83 µg/cm2, Chromatic Jeltrate ® (138.21 µg/cm2 and Jeltrate® (79.61 µg/cm2. Conclusion: Plus Jeltrate® had the best performance in releasing fluoride, followed by Chromatic Ortho Jeltrate®, Chromatic Jeltrate® and conventional Jeltrate®..

An Overview of Liquid Fluoride Salt Heat Transport Systems

Energy Technology Data Exchange (ETDEWEB)

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

2010-09-01

, and this report also describes more recently developed technologies such as dry gas seals. This report also provides a high-level, parametric evaluation of LSHT loop performance to allow general intercomparisons between heat-transport fluid options as well as provide an overview of the properties and requirements for a representative loop. A compilation of relevant thermophysical properties of useful fluoride salts is also included for salt heat transport systems. Fluoride salts can be highly corrosive depending on the container materials selected, the salt chemistry, and the operating procedures used. The report includes an overview of the state-of-the-art in reduction-oxidation chemistry control methodologies employed to minimize corrosion issues. Salt chemistry control technology, however, remains at too low a level of understanding for widespread industrial usage. Loop operational issues such as start-up procedures and system freeze-up vulnerability are also discussed. Liquid fluoride salts are a leading candidate heat transport medium for high-temperature applications. This report provides an overview of the current status of liquid salt heat transport technology. The report includes a high-level, parametric evaluation of liquid fluoride salt heat transport loop performance to allow intercomparisons between heat-transport fluid options as well as providing an overview of the properties and requirements for a representative loop. Much of the information presented here derives from the earlier molten salt reactor program and a significant advantage of fluoride salts, as high temperature heat transport media is their consequent relative technological maturity. The report also includes a compilation of relevant thermophysical properties of useful heat transport fluoride salts. Fluoride salts are both thermally stable and with proper chemistry control can be relatively chemically inert. Fluoride salts can, however, be highly corrosive depending on the container

Fluoride Levels in Urine, Blood Plasma and Serum of People Living in an Endemic Fluorosis Area in the Thar Desert, Pakistan

International Nuclear Information System (INIS)

Rafique, T.; Shirin, K.; Ahmed, I.; Khan, M. H.; Soomro, F.

2015-01-01

Fluoride (F/sup -/) levels in the urine, blood plasma and serum samples of people living in a village in the Thar Desert have been analysed where fluorosis is endemic and groundwater contains fluoride as high as 9.76 mg/L. Average values of fluoride levels in these human specimens i.e. urine, blood plasma and serum have been found to be 12.98 mg/L, 0.61 mg/L and 0.75 mg/L, respectively. These values are much higher than the normal values reported from other parts of the world. It was observed that urinary fluoride levels increase with age of an individual but with an insignificant correlation (r = 0.116), however, fluoride levels in plasma and serum samples did not vary considerably with age in male and female subjects. It has been found that after the age of 50 years the urinary fluoride decreases with its concomitant increase in serum fluoride level. Since groundwater is the only available source of water for human consumption and it contains higher fluoride (av. 7.09 mg/L) than WHO limit (1.5 mg/L), therefore, it is the main cause of fluorosis in the area. (author)

Enhancement of Saharan groundwater quality by reducing its fluoride concentration using different materials

KAUST Repository

Ramdani, Amina

2014-04-15

According to the environmental protection regulations, fluoride concentration is considered as a substance of priority for assessment of drinking water quality to determine their impacts on the environment and public health. Saharan groundwater (Algeria) contains an excess of fluoride ions. Regular consumption of this water by the population of the region may cause endemic fluorosis. To solve this problem, we propose to treat this water by adsorption on different materials, such as activated alumina (AA), sodium clay (SC), and hydroxyapatite (HAP) in order to enhance its quality by reducing its fluoride concentration. The maximum adsorption is achieved with an adsorption capacity of the order of 0.9, 0.667, and 0.370 mg/g and with a percentage of 90, 83.4, and 73.95% for AA, HAP, and SC, respectively. Indeed, the acidity and alkalinity of the medium significantly affect the adsorption of fluoride ions. Results deduced from the curves of adsorption isotherms of fluoride ions showed that the retention is predictable from these isotherms in agreement with the Langmuir model. The low removal of fluoride ions was observed in presence of (Formula presented.), (Formula presented.), and (Formula presented.) ions. Finally, AA material proved to be the best adsorbent for fluoride ions removal. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.

Fine structure of dielectric function of cadmium fluoride

International Nuclear Information System (INIS)

Kalugin, A.I.; Sobolev, V.V.

2005-01-01

Full text : The electric structure of solids has been extensively investigated for several decades within the density functional theory. However many problems are appeared. One of them, the problem of correct calculation of the transition matrix elements, is very important to calculate the optical properties of crystals. In many papers the results are obtained without taking into account the probabilities of transitions. The goal of this work is the calculation of spectrum with and without taking into account the matrix elements influence of matrix elements on the optical properties of cadmium fluoride. Also localizations of transitions in Brillouin Zone (BZ) were calculated. This work contains interesting information about the electronic structure of cadmium fluoride

Kinetic of the reductive chlorination of niobium pentoxide contained in a tin-bearing slag

International Nuclear Information System (INIS)

Moura, F.J.; Brocchi, E.A.; Kohler, H.M.

1987-01-01

Chlorination experiences were carried out with a tin-bearing slag, using charcoal as reducing agent, aiming to develop a mathematical model to represent the Kinetic of niobium pentoxide gasification. The results show a discrete effect for the initial percentage of reducing agent, when it is compared with the temperature influence. The Kinetic curves obtained by the mathematical equation present excellent agreement with experimental results. (M.C.K.) [pt

Physiology and toxicity of fluoride

Directory of Open Access Journals (Sweden)

Dhar Vineet

2009-01-01

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

Physiology and toxicity of fluoride.

Science.gov (United States)

Dhar, Vineet; Bhatnagar, Maheep

2009-01-01

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

Fluoride barriers in Nb/Pb Josephson junctions

Science.gov (United States)

Asano, H.; Tanabe, K.; Michikami, O.; Igarashi, M.; Beasley, M. R.

1985-03-01

Josephson tunnel junctions are fabricated using a new class of artificial barriers, metal fluorides (Al fluoride and Zr fluoride). These fluoride barriers are deposited on the surface of a Nb base electrode, which are previously cleaned using a CF4 cleaning process, and covered by a Pb counterelectrode. The junctions with both Al fluoride and Zr fluoride barriers exhibit good tunneling characteristics and have low specific capacitance. In the case of Zr fluoride, it is observed that reasonable resistances are obtained even at thickness greater than 100 A. This phenomenon might be explained by tunneling via localized states in Zr fluoride.

Effect of Tin, Copper and Boron on the Hot Ductility of 20CrMnTi Steel between 650 °C and 1100 °C

Science.gov (United States)

Peng, Hong-bing; Chen, Wei-qing; Chen, Lie; Guo, Dong

2015-02-01

The hot ductility of 20CrMnTi steel with x% tin, y% copper and z ppm boron (x = 0, 0.02; y = 0, 0.2; z = 0, 60) was investigated. The results show that tin and copper in 20CrMnTi steel are detrimental to its hot ductility while adding boron can eliminate the adverse effect and enhance hot ductility greatly. Tin is found to segregate to the boundaries tested by EPMA in 20CrMnTi steel containing tin and copper and tin-segregation is suppressed by adding boron, moreover, copper was found not to segregate to boundaries, however, fine copper sulfide was found from carbon extraction replicas using TEM. The adverse effect of tin and copper on the hot ductility was due mainly to tin segregation and fine copper sulfide in the steel. The proeutectoid ferrite film precipitating along the austenite grain boundary causes the ductility trough of the three examined steels. Tin and copper in 20CrMnTi steel can retard the occurrence of dynamic recrystallization (DRX) while boron-addition can compensate for that change. The beneficial effect of boron on 20CrMnTi steel containing tin and copper might be ascribed to the fact that boron segregates to grain boundaries, accelerates onset of DRX, retards austenite/ferrite transformation and promotes intragranular nucleation of ferrite.

Fluoride-associated ultrastructural changes and apoptosis in human renal tubule: a pilot study.

Science.gov (United States)

Quadri, J A; Sarwar, S; Sinha, A; Kalaivani, M; Dinda, A K; Bagga, A; Roy, T S; Das, T K; Shariff, A

2018-01-01

The susceptibility of the kidneys to fluoride toxicity can largely be attributed to its anatomy and function. As the filtrate moves along the complex tubular structure of each nephron, it is concentrated in the proximal and distal tubules and collecting duct. It has been frequently observed that the children suffering from renal impairments also have some symptoms of dental and skeletal fluorosis. The findings suggest that fluoride somehow interferes with renal anatomy and physiology, which may lead to renal pathogenesis. The aim of this study was to evaluate the fluoride-associated nephrotoxicity. A total of 156 patients with childhood nephrotic syndrome were screened and it was observed that 32 of them had significantly high levels ( p ≤ 0.05) of fluoride in urine (4.01 ± 1.83 ppm) and serum (0.1 ± 0.013 ppm). On the basis of urinary fluoride concentration, patients were divided into two groups, namely group 1 (G-1) ( n = 32) containing normal urine fluoride (0.61 ± 0.17 ppm) and group 2 (G-2) ( n = 32) having high urine fluoride concentration (4.01 ± 1.83 ppm). Age-matched healthy subjects ( n = 33) having normal levels of urinary fluoride (0.56 ± 0.15 ppm) were included in the study as control (group 0 (G-0)). Kidney biopsies were taken from G-1 and G-2 only, who were subjected to ultrastructural (transmission electron microscopy) and apoptotic (terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling) analysis. Various subcellular ultrastructural changes including nuclear disintegration, chromosome condensation, cytoplasmic ground substance lysis, and endoplasmic reticulum blebbing were observed. Increased levels of apoptosis were observed in high fluoride group (G-2) compared to normal fluoride group (G-1). Various degrees of fluoride-associated damages to the architecture of tubular epithelia, such as cell swelling and lysis, cytoplasmic vacuolation, nuclear condensation, apoptosis, and necrosis, were observed.

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

Science.gov (United States)

2014-01-01

Fluorine is the world's 13th most abundant element and constitutes 0.08% of the Earth crust. It has the highest electronegativity of all elements. Fluoride is widely distributed in the environment, occurring in the air, soils, rocks, and water. Although fluoride is used industrially in a fluorine compound, the manufacture of ceramics, pesticides, aerosol propellants, refrigerants, glassware, and Teflon cookware, it is a generally unwanted byproduct of aluminium, fertilizer, and iron ore manufacture. The medicinal use of fluorides for the prevention of dental caries began in January 1945 when community water supplies in Grand Rapids, United States, were fluoridated to a level of 1 ppm as a dental caries prevention measure. However, water fluoridation remains a controversial public health measure. This paper reviews the human health effects of fluoride. The authors conclude that available evidence suggests that fluoride has a potential to cause major adverse human health problems, while having only a modest dental caries prevention effect. As part of efforts to reduce hazardous fluoride ingestion, the practice of artificial water fluoridation should be reconsidered globally, while industrial safety measures need to be tightened in order to reduce unethical discharge of fluoride compounds into the environment. Public health approaches for global dental caries reduction that do not involve systemic ingestion of fluoride are urgently needed. PMID:24719570

Evaluation of a dentifrice containing 8% arginine, calcium carbonate, and sodium monofluorophosphate to repair acid-softened enamel using an intra-oral remineralization model.

Science.gov (United States)

Sullivan, R; Rege, A; Corby, P; Klaczany, G; Allen, K; Hershkowitz, D; Goldder, B; Wolff, M

2014-01-01

An intra-oral remineralization study was conducted to compare the ability of a dentifrice containing 8% arginine and calcium carbonate (Pro-Argin Technology), and 1450 ppm fluoride as sodium monofluorophosphate (MFP) to remineralize acid-softened bovine enamel specimens compared to a silica-based dentifrice with 1450 ppm fluoride as MFP. The intra-oral clinical study employed a double blind, two-treatment, crossover design, and used an upper palatal retainer to expose the enamel specimens to the oral environment during product use and periods of remineralization. The retainer was designed to house three partially demineralized bovine enamel samples. The study population was comprised of 30 adults, ages 18 to 70 years. The study consisted of two treatment phases with a washout period lasting seven (+/- three) days preceding each treatment phase. A silica-based dentifrice without fluoride was used during the washout period. The Test Dentifrice used in this study contained 8% arginine, calcium carbonate, and 1450 ppm fluoride as sodium monofluorophosphate (MFP). The Control Dentifrice was silica-based and contained 1450 ppm fluoride as MFP. The treatment period consisted of a three-day lead-in period with the assigned product. The panelists brushed two times per day during the three-day lead-in period with the assigned product. On the fourth day, the panelists began brushing with the assigned product with the retainer in their mouth. The panelists brushed for one minute, followed by a one-minute swish with the slurry and a rinse with 15 ml of water in the morning, in the afternoon, and night with the retainer in the mouth. The panelists brushed only their teeth and not the specimens directly. Changes in mineral content before and after treatment were measured using a Knoop microhardness tester. The results of the study showed that percent remineralization values for the Test Dentifrice and Control Dentifrice were 14.99% and 8.66%, respectively. A statistical analysis

Structure and phase transformation behavior of electroless Ni-P alloys containing tin and tungsten

International Nuclear Information System (INIS)

Balaraju, J.N.; Jahan, S. Millath; Jain, Anjana; Rajam, K.S.

2007-01-01

Autocatalytic ternary Ni-Sn-P, Ni-W-P and quaternary Ni-W-Sn-P films were prepared using alkaline citrate-based baths and compared with binary Ni-P coatings. Energy dispersive analysis of X-ray (EDAX) showed that binary Ni-P deposit contained 11.3 wt.% of phosphorus. Codeposition of tungsten in Ni-P matrix resulted in ternary Ni-W-P with 5 wt.% P and 7.8 wt.% of tungsten. Incorporation of tin led to ternary Ni-Sn-P deposit containing 0.4 wt.% Sn and 10.3 wt.% P. Presence of both sodium tungstate and sodium stannate in the basic bath had resulted in quaternary coating with 6.9 wt.% W, traces of Sn and 6.4 wt.% P. X-ray diffraction patterns of all the deposits revealed a single, broad peak which showed the nanocrystalline nature of the deposits. For the first time in related literature, the presence of a metastable phase Ni 12 P 5 in ternary deposits is reported in the present study. Metallographic cross-sections of all the deposits revealed the banded/lamellar structure. Scanning electron microscopy (SEM) studies of the deposits showed smooth nodules for ternary deposits, but coarse and well-defined nodules for quaternary deposits. DSC studies of phase transformation behavior of the ternary Ni-Sn-P deposit revealed a single sharp exothermic peak at 365 o C. However, ternary Ni-W-P and quaternary Ni-W-Sn-P deposits exhibited a low temperature peak at 300 o C, a split type high temperature peak at 405 and 440 o C and a very high temperature peak at 550 o C. Higher activation energy values were obtained for W-based alloy deposits. Presence of W and Sn has helped to retain high microhardness values even at higher temperatures indicating an improved thermal stability

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

Science.gov (United States)

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 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 for 21st century medical care.

49 CFR 173.163 - Hydrogen fluoride.

Science.gov (United States)

2010-10-01

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

Study of optical characteristics of tin oxide thin film prepared by sol ...

Indian Academy of Sciences (India)

wear-resistant coating on glass containers (Nakagawa et al. 1997), Infrared reflectors for ... Tin oxide is a tetragonal n-type semiconductor having high bandgap energy ... (IV) chloride due to the cost factor and availability. The main purpose of ...

Fluoride in groundwater: toxicological exposure and remedies.

Science.gov (United States)

Jha, S K; Singh, R K; Damodaran, T; Mishra, V K; Sharma, D K; Rai, Deepak

2013-01-01

Fluoride is a chemical element that is found most frequently in groundwater and has become one of the most important toxicological environmental hazards globally. The occurrence of fluoride in groundwater is due to weathering and leaching of fluoride-bearing minerals from rocks and sediments. Fluoride when ingested in small quantities (dental health by reducing dental caries, whereas higher concentrations (>1.5 mg/L) may cause fluorosis. It is estimated that about 200 million people, from among 25 nations the world over, may suffer from fluorosis and the causes have been ascribed to fluoride contamination in groundwater including India. High fluoride occurrence in groundwaters is expected from sodium bicarbonate-type water, which is calcium deficient. The alkalinity of water also helps in mobilizing fluoride from fluorite (CaF2). Fluoride exposure in humans is related to (1) fluoride concentration in drinking water, (2) duration of consumption, and (3) climate of the area. In hotter climates where water consumption is greater, exposure doses of fluoride need to be modified based on mean fluoride intake. Various cost-effective and simple procedures for water defluoridation techniques are already known, but the benefits of such techniques have not reached the rural affected population due to limitations. Therefore, there is a need to develop workable strategies to provide fluoride-safe drinking water to rural communities. The study investigated the geochemistry and occurrence of fluoride and its contamination in groundwater, human exposure, various adverse health effects, and possible remedial measures from fluoride toxicity effects.

Determination of fluoride in spices using microwave induced oxygen combustion

Directory of Open Access Journals (Sweden)

Emanuel Šucman

2012-01-01

Full Text Available Fluorine is essential in human and/or animal nutrition; therefore, so it is important to know its concentration in a diet. One of the possible sources of fluorine for humans is spice, containing various amounts of this trace element. This work describes the method for fluoride determination in various kinds ofspices using microwave-supported sample preparation in high pressure oxygen atmosphere followed by potentiometry with a fluoride ion-selective electrode. Parameters of the microwave device for combustion procedure were checked and optimized in order to find settings ensuring complete sample combustion and/or absorption of the analyte in the absorption solution. For the ion-selective electrode measurement, the technique of standard straight line was chosen. Concentrations of fluorides in spices and spice blends under investigation ranged from 3.15 mg·kg-1 to 26.08 mg·kg-1. In order to check the accuracy of the method Certified Reference Material Fluoride in Vegetation NIST 2695 was used and a good agreement between certified and found values was found. The precision expressed as the relative standard deviation ranged from 0.6% to 5.0%. The method is fast, accurate and reliable for this kind of analysis. In recent literature data on fluoride concentrations in spices and/or spice blends have not been found.

Methods for chemical recovery of non-carrier-added radioactive tin from irradiated intermetallic Ti-Sb targets

Science.gov (United States)

Lapshina, Elena V [Troitsk, RU; Zhuikov, Boris L [Troitsk, RU; Srivastava, Suresh C [Setauket, NY; Ermolaev, Stanislav V [Obninsk, RU; Togaeva, Natalia R [Obninsk, RU

2012-01-17

The invention provides a method of chemical recovery of no-carrier-added radioactive tin (NCA radiotin) from intermetallide TiSb irradiated with accelerated charged particles. An irradiated sample of TiSb can be dissolved in acidic solutions. Antimony can be removed from the solution by extraction with dibutyl ether. Titanium in the form of peroxide can be separated from tin using chromatography on strong anion-exchange resin. In another embodiment NCA radiotin can be separated from iodide solution containing titanium by extraction with benzene, toluene or chloroform. NCA radiotin can be finally purified from the remaining antimony and other impurities using chromatography on silica gel. NCA tin-117m can be obtained from this process. NCA tin-117m can be used for labeling organic compounds and biological objects to be applied in medicine for imaging and therapy of various diseases.

Corrosion resistance of stainless steel, nickel-titanium, titanium molybdenum alloy, and ion-implanted titanium molybdenum alloy archwires in acidic fluoride-containing artificial saliva: An in vitro study

Directory of Open Access Journals (Sweden)

Venith Jojee Pulikkottil

2016-01-01

Full Text Available Objective: (1 To evaluate the corrosion resistance of four different orthodontic archwires and to determine the effect of 0.5% NaF (simulating high fluoride-containing toothpaste of about 2250 ppm on corrosion resistance of these archwires. (2 To assess whether surface roughness (Ra is the primary factor influencing the corrosion resistance of these archwires. Materials and Methods: Four different archwires (stainless steel [SS], nickel-titanium [NiTi], titanium molybdenum alloy [TMA], and ion-implanted TMA were considered for this study. Surface characteristics were analyzed using scanning electron microscopy, atomic force microscopy (AFM, and energy dispersive spectroscopy. Linear polarization test, a fast electrochemical technique, was used to evaluate the corrosion resistance, in terms of polarization resistance of four different archwires in artificial saliva with NaF concentrations of 0% and 0.5%. Statistical analysis was performed by one-way analysis of variance. Results: The potentiostatic study reveals that the corrosion resistance of low-friction TMA (L-TMA > TMA > NiTi > SS. AFM analysis showed the surface Ra of TMA > NiTi > L-TMA > SS. This indicates that the chemical composition of the wire is the primary influential factor to have high corrosion resistance and surface Ra is only secondary. The corrosion resistance of all wires had reduced significantly in 0.5% acidic fluoride-containing artificial saliva due to formation of fluoride complex compound. Conclusion: The presence of 0.5% NaF in artificial saliva was detrimental to the corrosion resistance of the orthodontic archwires. Therefore, complete removal of residual high-fluorinated toothpastes from the crevice between archwire and bracket during tooth brushing is mandatory.

Risk Assessment Study of Fluoride Salts: Probability-Impact Matrix of Renal and Hepatic Toxicity Markers.

Science.gov (United States)

Usuda, Kan; Ueno, Takaaki; Ito, Yuichi; Dote, Tomotaro; Yokoyama, Hirotaka; Kono, Koichi; Tamaki, Junko

2016-09-01

The present risk assessment study of fluoride salts was conducted by oral administration of three different doses of sodium and potassium fluorides (NaF, KF) and zinc fluoride tetrahydrate (ZnF2 •4H2O) to male Wistar rats. The rats were divided into control and nine experimental groups, to which oral injections of 0.5 mL distilled water and 0.5 mL of fluoride solutions, respectively, were given. The dosage of fluoride compounds was adjusted to contain 2.1 mg (low-dose group, LG), 4.3 mg (mid-dose group, MG), and 5.4 mg fluoride per 200 g rat body weight (high-dose group, HG) corresponding to 5, 10, and 12.5 % of LD50 values for NaF. The 24-h urine volume, N-acetyl-β-D-glucosaminidase (NAG) and creatinine clearance (Ccr) were measured as markers of possible acute renal impact. The levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined in serum samples as markers of acute hepatic impact. The levels of serum and urinary fluoride were determined to evaluate fluoride bioavailability. The results reveal that higher doses of NaF, KF, and ZnF2 induced renal damage as indicated by higher urinary NAG (p fluoride is a potential, dose-dependent risk factor of renal tubular damage.

The influence of lifelong exposure to environmental fluoride on bone quality in humans

Science.gov (United States)

Chachra, Debbie

The objective of this study was to determine if lifelong exposure to environmental sources of fluoride (including fluoridated water) had an effect on bone quality in humans. Ninety-two femoral heads were obtained from individuals undergoing total hip arthroplasty in regions with and without fluoridated water (Toronto and Montreal, respectively), so that the donors would have had a wide range of fluoride exposure. As the samples were obtained at surgery, the femoral heads were affected by osteoarthritis (75), osteoporosis (9) and other diseases. The fluoride content of cancellous bone was assessed by instrumental neutron activation analysis. A number of contributors to bone quality were assessed. The compressive and torsional mechanical properties were measured for cancellous cores excised from the centre of the femoral head. The architecture was assessed by image analysis of an x-ray of a 5 mm thick coronal section of the femoral head, as well as of histological sections taken from the superior (weightbearing) and the inferior (nonweightbearing) surface of the femoral head. The degree of mineralization was measured using backscattered electron imaging and microhardness, again at the superior and the inferior surface. Femoral heads from Toronto donors had a greater mean fluoride content than those from Montreal donors (1033 +/- 438 ppm vs. 643 +/- 220 ppm). However, the fluoride content of the Toronto donors ranged approximately twelve-fold (192--2264 ppm) and entirely contained the range of Montreal donors. Therefore, fluoridated water exposure is not the only determinant of fluoride content. The logarithm of the bone fluoride content increased with age. No substantive effect of fluoride, independent of age, was observed for the mechanical properties. Similarly, at the inferior surface, the architecture was affected by age but not by fluoride incorporation but the degree of mineralization was not affected by either. However, the degree of mineralization (measured

Fluoride Uptake Profiles of Selected European Toothpastes into Hard Tissues and Plaque.

Science.gov (United States)

Moore, Joel; Schneiderman, Eva; Farmer, Teresa; Zsiska, Marianne

2017-09-01

To compare the fluoridating potential of selected European toothpastes using a combination of enamel, dentin, and plaque in vitromodels. Four in vitromodels were included: 1) Enamel Fluoride (F) Uptake (EFU); 2) Dentin F Uptake (DFU); 3) Enamel Solubility Reduction (ESR); and 4) Plaque F Uptake (PFU). A core set of marketed products was included in all studies, plus a standard toothpaste (1100 ppm F as NaF/silica) and placebo control (the PFU study did not include a placebo control). Test dentifrices: [A] Fluocaril® Bi-Fluoré 250 (1500 ppm F as NaF+1000 ppm F as SMFP); [B] LacerAnticaries (2500 ppm F as SMFP); [C] Elmex® Caries Professional™ (1450 ppm F as SMFP+1.5% arginine); [D] Colgate® Triple Action (1450 ppm F as SMFP); [E] Placebo (0 ppm F); and [F] standard toothpaste (1100 ppm as NaF/silica). In all studies (EFU, DFU, ESR, and PFU), assessments were compared for each pair using the Tukey-Kramer HSD test (p F = B = C = D > E; DFU: A > F = B = C = D = E; PFU: A = B > F = C = D). In demineralization prevention, the Fluocaril dentifrice [A] also provided the greatest benefit (ESR: A = F = C = B = D > E). In all studies that included a placebo control, all of the F-containing dentifrices performed better than the placebo control. While these results demonstrate that all of the marketed products tested provide effective anticaries benefits, the Fluocaril Bi-Fluoré 250 dentifrice consistently delivered unsurpassed performance. It delivered the highest level of F to plaque, provided greater measures of efficacy in both remineralization and inhibition of demineralization, and delivered substantial improvement in fluoridation of dentin, suggesting the potential for delivering both coronal and root caries benefits.

Physiology and toxicity of fluoride

OpenAIRE

Dhar Vineet; Bhatnagar Maheep

2009-01-01

Fluoride has been described as an essential element needed for normal development and growth of animals and extremely useful for human beings. Fluoride is abundant in the environment and the main source of fluoride to humans is drinking water. It has been proved to be beneficial in recommended doses, and at the same time its toxicity at higher levels has also been well established. Fluoride gets accumulated in hard tissues of the body and has been know to play an important role in mineralizat...

Advantages of liquid fluoride thorium reactor in comparison with light water reactor

Energy Technology Data Exchange (ETDEWEB)

Bahri, Che Nor Aniza Che Zainul, E-mail: anizazainul@gmail.com; Majid, Amran Ab.; Al-Areqi, Wadeeah M. [Nuclear Science Program, School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

2015-04-29

Liquid Fluoride Thorium Reactor (LFTR) is an innovative design for the thermal breeder reactor that has important potential benefits over the traditional reactor design. LFTR is fluoride based liquid fuel, that use the thorium dissolved in salt mixture of lithium fluoride and beryllium fluoride. Therefore, LFTR technology is fundamentally different from the solid fuel technology currently in use. Although the traditional nuclear reactor technology has been proven, it has perceptual problems with safety and nuclear waste products. The aim of this paper is to discuss the potential advantages of LFTR in three aspects such as safety, fuel efficiency and nuclear waste as an alternative energy generator in the future. Comparisons between LFTR and Light Water Reactor (LWR), on general principles of fuel cycle, resource availability, radiotoxicity and nuclear weapon proliferation shall be elaborated.

Recovery of protactinium from molten fluoride nuclear fuel compositions

Science.gov (United States)

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

1973-12-25

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

Thermodynamic investigation of fluoride salts for nuclear energy production

International Nuclear Information System (INIS)

Beilmann, Markus

2013-01-01

In this work thermodynamic properties of molten fluoride salts and salt mixtures are investigated. Fluoride salts have advantageous properties to be used in energy producing systems based on the conversion from heat to energy like i.e in Molten Salt Reactors. For this purpose it is very important to have detailed information about the heat capacity of the pure salts and salt mixtures. To get a better understanding about the heat capacity in mixtures drop calorimetry measurements of mixtures of LiF with other alkali fluorides were conducted and compared. The investigation of fluoride salts at elevated temperatures is complicated by the fact that fluoride vapour is aggressive to many materials. In order to protect our sensitive measurement equipment the salt samples were encapsulated in nickel crucibles using a laser welding technique and afterwards the whole nickel capsule was measured. This method was verified by the measurement of unmixed CsF and KF where in both examples an excellent agreement with literature data was obtained. Afterwards various intermediate compositions of the systems LiF-KF, LiF-CsF and LiF-RbF were investigated and a general trend according to the difference in cation radii could be established. In combination with literature data for the LiF-NaF system the heat capacity of the liquid state follows the order LiF-NaF 2 -LaF 3 phase diagram was obtained. With the help of mathematical models the phase diagrams can be calculated and also higher order systems can be predicted. The LiF-NaF-CaF 2 -LaF 3 system was calculated with the classical polynomial model and the quasi-chemical model in parallel in order to evaluate which of the two models provide a better extrapolation to higher order systems (ternary or quaternary) based on the related binary systems. The two models behaved very similar at the investigated system and the quasi-chemical model was chosen for further assessments of phase diagrams. This model was selected, since it considers the

Experimental facilities for research of properties and behaviour of fluoride salts

International Nuclear Information System (INIS)

Hosnedl, P.; Jilek, M.; Kroc, V.; Pedal, L.; Valenta, V.; Vodicka, J.

1999-01-01

SKODA JS s.r.o. (Czech leading nuclear technology manufacturer) prepared and manufactured experimental loops for research and verification of properties and behaviour of fluoride salts for primary and secondary circuit, construction materials and ADTT systems technological components for the operation in the Nuclear Research Institute Rez plc fluorine chemistry laboratory. This paper presents charts and experimental program for molten fluoride salts experimental loops with natural circulation. Further on, the paper describes extension of the loops for research with forced circulation and next works for steam generator model verification and connection with the loop of Energovyzkum Brno. The loops are designed and constructed to obtain a sufficient amount of experience on ADTT technology. The research and utilisation program covers questions of corrosion and intergranular corrosion of structural materials, research of material properties and welding, research of fluoride fluid properties, measuring of thermo-hydraulic properties of molten salt fluoride fluids, heat transfer and hydraulics, development and tests of some plant components (steam generators, heat exchangers, pumps, valves) and other engineering issues. Two electrolyzers have been manufactured for the research of fuel/coolant fluoride salts mixture purification. One for the production of hydrogen fluoride, and the other for the research of salts purification. (author)

Biological effects data: Fluoride and sulfur dioxide

Energy Technology Data Exchange (ETDEWEB)

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

1975-04-01

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

Fluoride resistance in Streptococcus mutans

NARCIS (Netherlands)

Liao, Ying

2017-01-01

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

Molecular mechanisms of fluoride toxicity.

Science.gov (United States)

Barbier, Olivier; Arreola-Mendoza, Laura; Del Razo, Luz María

2010-11-05

Halfway through the twentieth century, fluoride piqued the interest of toxicologists due to its deleterious effects at high concentrations in human populations suffering from fluorosis and in in vivo experimental models. Until the 1990s, the toxicity of fluoride was largely ignored due to its "good reputation" for preventing caries via topical application and in dental toothpastes. However, in the last decade, interest in its undesirable effects has resurfaced due to the awareness that this element interacts with cellular systems even at low doses. In recent years, several investigations demonstrated that fluoride can induce oxidative stress and modulate intracellular redox homeostasis, lipid peroxidation and protein carbonyl content, as well as alter gene expression and cause apoptosis. Genes modulated by fluoride include those related to the stress response, metabolic enzymes, the cell cycle, cell-cell communications and signal transduction. The primary purpose of this review is to examine recent findings from our group and others that focus on the molecular mechanisms of the action of inorganic fluoride in several cellular processes with respect to potential physiological and toxicological implications. This review presents an overview of the current research on the molecular aspects of fluoride exposure with emphasis on biological targets and their possible mechanisms of involvement in fluoride cytotoxicity. The goal of this review is to enhance understanding of the mechanisms by which fluoride affects cells, with an emphasis on tissue-specific events in humans. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

The determination, by x-ray-fluorescence spectrometry, of tin and zinc in ores, middlings, and residues

International Nuclear Information System (INIS)

Balaes, A.M.E.

1984-01-01

The method of analysis is applicable to samples with tin and zinc contents from 15μg/g upwards. Samples with widely ranging concentrations of the analytes are diluted with river sand. The matrix variations are compensated for by the use of briquettes containing coarse river sand, a styrene copolymer binder, and an internal standard. Tungsten is used as the internal standard for zinc, and antimony for tin. Calibration graphs for zinc and tin are obtained by the use of a reference material for tin and of zinc oxide for zinc. The precision of the analysis for each element does not exeed 0,040 relative standard deviation. The agreement between the analysis and the accepted international values and recommended values for in-house reference materials is better than 3 per cent over the concentration range 50μg/g to 16 per cent. The lower limits of detection are 2μg/g for tin and 3μg/g for zinc. The overall time required for the analysis of 10 samples, one control sample, and five calibration standards is approximately 3 hours

Fluoride-releasing restorative materials and secondary caries.

Science.gov (United States)

Hicks, John; Garcia-Godoy, Franklin; Donly, Kevin; Flaitz, Catherine

2003-03-01

Secondary caries is responsible for 60 percent of all replacement restorations in the typical dental practice. Risk factors for secondary caries are similar to those for primary caries development. Unfortunately, it is not possible to accurately predict which patients are at risk for restoration failure. During the past several decades, fluoride-releasing dental materials have become a part of the dentist's armamentarium. Considerable fluoride is released during the setting reaction and for periods up to eight years following restoration placement. This released fluoride is readily taken up by the cavosurface tooth structure, as well as the enamel and root surfaces adjacent to the restoration. Resistance against caries along the cavosurface and the adjacent smooth surface has been shown in both in vitro and in vivo studies. Fluoride-releasing dental materials provide for improved resistance against primary and secondary caries in coronal and root surfaces. Plaque and salivary fluoride levels are elevated to a level that facilitates remineralization. In addition, the fluoride released to dental plaque adversely affects the growth of lactobacilli and mutans streptococci by interference with bacterial enzyme systems. Fluoride recharging of these dental materials is readily achieved with fluoridated toothpastes, fluoride mouthrinses, and other sources of topical fluoride. This allows fluoride-releasing dental materials to act as intraoral fluoride reservoirs. The improvement in the properties of dental materials with the ability to release fluoride has improved dramatically in the past decade, and it is anticipated that in the near future the vast majority of restorative procedures will employ fluoride-releasing dental materials as bonding agents, cavity liners, luting agents, adhesives for orthodontic brackets, and definitive restoratives.

Consumer Products Containing Radioactive Materials

Science.gov (United States)

Fact Sheet Adopted: February 2010 Health Physics Society Specialists in Radiation Safety Consumer Products Containing Radioactive Materials Everything we encounter in our daily lives contains some radioactive material, ...

Removal of heavy metals from metal-containing effluent by yeast ...

African Journals Online (AJOL)

Removal of heavy metals from metal-containing effluent by yeast biomass. ... Research studies have described this phenomenon of fast initial sorption with a ... chrome and tin from the chrome and tin effluents of a local iron and steel industry.

The synthesis and structural characterization of novel transition metal fluorides

Energy Technology Data Exchange (ETDEWEB)

Casteel, W.J. Jr.

1992-09-01

High purity KMF[sub 6] and K[sub 2]MF[sub 6] salts (M = Mo,Re, Ru, Os, Ir, Pt) are obtained from reduction hexafluorides. A rhombohedral unit cell is observed for KReF[sub 6]. Fluoride ion capture by Lewis acids from the hexafluorometallate (IV) salts affords high purity tetrafluorides for M = Mo, Re, Ru, Os, and Pd. The structure of RuF[sub 4] is determined from X-ray synchrotron and neutron powder data. Unit cells based on theorthorhombic PdF[sub 4] type cell are derived from X-ray powder data for ReF[sub 4] and OsF[sub 4]. Fluoride ion capture from KAgF[sub 4] provides the thermally unstable trifluoride as a bright, red, diamagnetic solid. The structure solution of AgF[sub 3] and redetermination of the AuF[sub 3] structure from X-ray synchrotron and neutron powder data demonstrate that the two are isostnictural. Thermal decomposition product of AgF[sub 3] is the mixed valence compound Ag[sup II]Ag[sub 2][sup III]F[sub 8]. Several new salts containing the (Ag - F)[sub n][sup n+] chain cation are prepared. The first linear (Ag - F)[sub n][sup n+] chain is observed in AgF[sup +]BF[sub 4 [sup [minus

Preparation of bromine fluoride; Preparation du fluorure de brome

Energy Technology Data Exchange (ETDEWEB)

Domange, Pr; Duflo, J.

1958-05-15

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

Synthesis and characterization of titania nanotubes by anodizing of titanium in fluoride containing electrolytes

Science.gov (United States)

Ahmad, Akhlaq; Haq, Ehsan Ul; Akhtar, Waseem; Arshad, Muhammad; Ahmad, Zubair

2017-11-01

Titania nanotubular structure was prepared by anodizing titanium metal in the fluoride containing electrolytes and studied for hydrogen reduction using photo electrochemical cell. Potentiodynamic scan was performed before actual anodizing to optimize the anodizing conditions. The morphology of the TiO2 nanotubes was investigated by SEM and the presence of TiO2 nanotubes was confirmed. Raman spectroscopy was done to confirm the different phases present. Hydrogen generation capability was revealed by electrochemical testing in three-electrode system in dark and in visible light at 200 W power using Gamry Potentiostat. The corrosion potential of TiO2 nanotubes produced was found to be more active side in potassium hydroxide solution under visible light than in the dark condition. Cathodic polarization behavior of specimens in the presence of light showed more activity towards hydrogen generation than in dark condition. In comparison, the hydrogen generation capability of specimen anodized in 2H15 electrolyte was higher than specimens anodized in other electrolytes. Electrochemical impedance spectroscopy was used to study the charge transfer resistance of the nanotubes produced. The results showed that TiO2 nanotubular structure is a promising material for photoelectrochemical cell. Low-charge transfer resistance also depicts that it can be efficiently used to harvest solar energy.

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

Science.gov (United States)

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

1988-01-01

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

Terrestrial bryophytes as indicators of fluoride emission from a phosphorus plant, Long Harbour, Newfoundland, Canada

Energy Technology Data Exchange (ETDEWEB)

Roberts, B.A.; Thompson, L.K.; Sidhu, S.S.

1979-01-01

A study of the effects of fluoride emissions (HF, SiF/sub 4/) on certain species of bryophytes was carried out in the vicinity of an industrial palnt producing elemental phosphorus at Long Harbour, Nfld. Damage symptoms varied from mild phyllid chlorosis (yellowing) to severe browning of up to 95% of the phyllids. Polytrichum commune Hedw. was the main bryophyte species used in the survey. Random collections from 45 sample sites were analysed for total fluoride. The fluoride concentrations in phyllid tissue ranged from a high of 6066 ppm (dry weight) at a distance of 1 km northeast of the emission source to 44 ppm (dry weight) 11.7 km northeast of the emission source in the direction of the prevailing wind. Control samples were obtained from similar sites in areas far removed from the industrial plant and contained, on average, 11.3 ppm (dry weight). The concentration of fluoride in the bryophyte phyllid tissue was inversely correlated with distance from the emission source, in the direction of the prevailing wind. The severity of acropetal scorching was found to be correlated with the concentration of fluoride in the bryophyte phyllid tissue, and in addition, samples high in fluoride had fewer sporophytes. Fluoride concentrations in bryophyte tissue are compared with concentrations of fluoride in the needles of balsam fir, Abies Balsamea I., in four damage zones, and also with available and total fluoride in soil humus and concentrations of fluoride in air. The total area affected by fluoride emissions was increased using bryophytes as the pollution indicator species, especially in areas far from the industrial plant.

Photovoltaic semiconductor materials based on alloys of tin sulfide, and methods of production

Science.gov (United States)

Lany, Stephan

2016-06-07

Photovoltaic thin-film materials comprising crystalline tin sulfide alloys of the general formula Sn.sub.1-x(R).sub.xS, where R is selected from magnesium, calcium and strontium, as well as methods of producing the same, are disclosed.

Sintered indium-tin oxide particles induce pro-inflammatory responses in vitro, in part through inflammasome activation.

Directory of Open Access Journals (Sweden)

Melissa A Badding

Full Text Available Indium-tin oxide (ITO is used to make transparent conductive coatings for touch-screen and liquid crystal display electronics. As the demand for consumer electronics continues to increase, so does the concern for occupational exposures to particles containing these potentially toxic metal oxides. Indium-containing particles have been shown to be cytotoxic in cultured cells and pro-inflammatory in pulmonary animal models. In humans, pulmonary alveolar proteinosis and fibrotic interstitial lung disease have been observed in ITO facility workers. However, which ITO production materials may be the most toxic to workers and how they initiate pulmonary inflammation remain poorly understood. Here we examined four different particle samples collected from an ITO production facility for their ability to induce pro-inflammatory responses in vitro. Tin oxide, sintered ITO (SITO, and ventilation dust particles activated nuclear factor kappa B (NFκB within 3 h of treatment. However, only SITO induced robust cytokine production (IL-1β, IL-6, TNFα, and IL-8 within 24 h in both RAW 264.7 mouse macrophages and BEAS-2B human bronchial epithelial cells. Our lab and others have previously demonstrated SITO-induced cytotoxicity as well. These findings suggest that SITO particles activate the NLRP3 inflammasome, which has been implicated in several immune-mediated diseases via its ability to induce IL-1β release and cause subsequent cell death. Inflammasome activation by SITO was confirmed, but it required the presence of endotoxin. Further, a phagocytosis assay revealed that pre-uptake of SITO or ventilation dust impaired proper macrophage phagocytosis of E. coli. Our results suggest that adverse inflammatory responses to SITO particles by both macrophage and epithelial cells may initiate and propagate indium lung disease. These findings will provide a better understanding of the molecular mechanisms behind an emerging occupational health issue.

Advanced optical modeling of TiN metal hard mask for scatterometric critical dimension metrology

Science.gov (United States)

Ebersbach, Peter; Urbanowicz, Adam M.; Likhachev, Dmitriy; Hartig, Carsten

2017-03-01

The majority of scatterometric production control models assume constant optical properties of the materials and only dimensional parameters are allowed to vary. However, this assumption, especially in case of thin-metal films, negatively impacts model precision and accuracy. In this work we focus on optical modeling of the TiN metal hardmask for scatterometry applications. Since the dielectric function of TiN exhibits thickness dependence, we had to take this fact into account. Moreover, presence of the highly absorbing films influences extracted thicknesses of dielectric layers underneath the metal films. The later phenomenon is often not reflected by goodness of fit. We show that accurate optical modeling of metal is essential to achieve desired scatterometric model quality for automatic process control in microelectronic production. Presented modeling methodology can be applied to other TiN applications such as diffusion barriers and metal gates as well as for other metals used in microelectronic manufacturing for all technology nodes.

Effect of theobromine-containing toothpaste on dentin tubule occlusion in situ.

Science.gov (United States)

Amaechi, Bennett T; Mathews, Sapna M; Mensinkai, Poornima K

2015-01-01

Dentin hypersensitivity (DH) is treated by either occlusion of dentin tubules or nerve desensitization. This in situ study compared dentin tubules occlusion by theobromine-containing dentifrices with (Theodent-classic-F®, TCF) and without (Theodent-classic®, TC) fluoride with 1,500 ppm fluoride toothpaste, Colgate®-Regular (Fluoride) and Novamin®-containing toothpaste, Sensodyne®-5000-Nupro (Novamin®). Each subject wore four intraoral appliances bearing dentin blocks while using one of four test dentifrices (n = 20/dentifrice) twice daily for 7 days. The four appliances were removed successively after 1, 2, 3, and 7 days. Treated blocks and their control (untreated) blocks were examined with scanning electron microscopy (SEM). Effects were compared statistically (ANOVA/Tukey's) based on percentage of surface area covered by deposited precipitate layer (%DPL) and percentage of fully open (%FOT), partially occluded (%POT), and completely occluded (%COT) tubules in each block calculated relative to the number of tubules in their control blocks. SEM observation indicated an increased %COT and %DPL over time. After 1 and 2 days, %COT was comparable with TC and TCF, and significantly (p Theobromine-containing toothpastes with and without fluoride have equal potential in occluding dentin tubules within a shorter time period than Novamin®-containing toothpaste; however, the three demonstrated equal potential after 1 week, but not the fluoride toothpaste. Theobromine-containing toothpaste promoted dentin tubule occlusion thus shows potential to relief DH.

In Vivo Remineralization of Artificial Carious Lesions using Calcifying Solution and Fluoride Solution

Directory of Open Access Journals (Sweden)

Els Sunarsih Budipramana