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Sample records for natural calcium fluoride

  1. Process for converting magnesium fluoride to calcium fluoride

    DOEpatents

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

    1984-12-21

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

  2. Ion chromatography detection of fluoride in calcium carbonate.

    PubMed

    Lefler, Jamie E; Ivey, Michelle M

    2011-09-01

    Fluoride in aquatic systems is increasing due to anthropogenic pollution, but little is known about how this fluoride affects organisms that live in and around aquatic habitats. Fluoride can bioaccumulate in structures comprised of calcium carbonate, such as shells and skeletons of both freshwater and saltwater species as diverse as snails, corals, and coccolithophorid algae. In this article, ion chromatography (IC) techniques are developed to detect and quantify fluoride in a matrix of calcium carbonate. Solid samples are dissolved in hydrochloric acid, pretreated to remove the majority of the chloride ions, and then analyzed using IC. With these methods, the 3σ limit of detection is 0.2 mg of fluoride/kg of calcium carbonate. PMID:21859530

  3. Thermochemistry of calcium oxide and calcium hydroxide in fluoride slags

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, S.; Mitchell, A.

    1990-08-01

    Calcium oxide activity in binary CaF2-CaO and ternary CaF2-CaO-Al2O3 and CaF2-CaO-SiO2 slags has been determined by CO2-slag equilibrium experiments at 1400 °C. The carbonate ca-pacity of these slags has also been computed and compared with sulfide capacity data available in the literature. The similarity in trends suggests the possibility of characterizing carbonate capacity as an alternative basicity index for fluoride-base slags. Slag-D2O equilibrium experi-ments are performed at 1400°C with different fluoride-base slags to determine water solubility at two different partial pressures of D2O, employing a new slag sampling technique. A novel isotope tracer detection technique is employed to analyze water in the slags. The water solubility data found show higher values than the previous literature data by an order of magnitude but show a linear relationship with the square root of water vapor partial pressure. The activity of hydroxide computed from the data is shown to be helpful in estimating water solubility in in-dustrial electroslag remelting (ESR) slags.

  4. A calcium prerinse required to form calcium fluoride in plaque from a sodium fluoride rinse.

    PubMed

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

    2014-01-01

    The purpose of this study is to determine whether a calcium (Ca) prerinse used before a 228 µg/g (ppm) fluoride (F) rinse would induce the formation of 'calcium fluoride-like' (CaF2-like) deposits in human dental plaque. Sixty minutes after the use of the Ca prerinse/F rinse, plaque samples were collected from 10 volunteers, homogenized, and split into 2 aliquots. The plaque mass from one aliquot was then extracted with a 'plaque-like' solution that extracted all the CaF2-like deposits. The total F in both aliquots was then determined and compared. The results demonstrated that, as in previous studies, the Ca prerinse induced large increases in plaque fluid and total plaque F. However, unlike previous results without the Ca prerinse, 30% of the plaque F deposits were CaF2 or CaF2-like. Given that maintaining an elevated F concentration in the vicinity of a developing lesion may play an important role in the cariostatic effect of this ion, and the potential advantages of CaF2-like deposits as an F source, these results suggest that a Ca prerinse may increase the cariostatic effect of topical agents.

  5. Calcium fluoride recovery from fluoride wastewater in a fluidized bed reactor.

    PubMed

    Aldaco, R; Garea, A; Irabien, A

    2007-02-01

    In order to contribute to better resource efficiency and industrial waste management leading to a sustainable production and consumption pattern new processes must be developed, which should be operated in such a way that waste production is reduced or avoided. Fluoride removal by precipitation generates huge amounts of a water rich sludge. Calcium fluoride is not recovered from the waste streams and it is not recycled due to the high water content and the low quality of the sludge. Crystallization process in a fluidized bed reactor (FBR) appears as an alternative technology to the conventional chemical precipitation process. In the crystallization process in a FBR silica sand is usually used as seed material, however silica is a deleterious impurity because it causes losses in the yield of HF and its content should be less than 1%. In this paper, granular calcite has been used as seed material in order to obtain synthetic calcium fluoride. According to the composition (CaF(2)>97%, SiO(2)<1%), the synthetic calcium fluoride from the crystallization process in a FBR is able to be recycled as raw material for the manufacture of hydrofluoric acid leading to a reduction of raw materials consumption. The crystallization process in a FBR to remove fluoride from industrial wastewaters contributes to an environmental friendly production, because it allows to reduce the waste production as well as to increase the recovery of materials.

  6. Pyrochemical recovery of plutonium from calcium fluoride reduction slag

    DOEpatents

    Christensen, D.C.

    A pyrochemical method of recovering finely dispersed plutonium metal from calcium fluoride reduction slag is claimed. The plutonium-bearing slag is crushed and melted in the presence of at least an equimolar amount of calcium chloride and a few percent metallic calcium. The calcium chloride reduces the melting point and thereby decreases the viscosity of the molten mixture. The calcium reduces any oxidized plutonium in the mixture and also causes the dispersed plutonium metal to coalesce and settle out as a separate metallic phase at the bottom of the reaction vessel. Upon cooling the mixture to room temperature, the solid plutonium can be cleanly separated from the overlying solid slag, with an average recovery yield on the order of 96 percent.

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

    PubMed

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

    2012-07-30

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

  8. Characterization of the terbium-doped calcium fluoride single crystal

    NASA Astrophysics Data System (ADS)

    Zheleznov, Dmitry S.; Starobor, Aleksey V.; Palashov, Oleg V.

    2015-08-01

    Optical, thermo-optical and magneto-optical characteristics of the terbium-doped (10 at.%) calcium fluoride sample were investigated. It was made the analysis, confirmed the possibility of development of a Faraday isolator and a cryogenic Faraday isolator based on the studied medium, which will provide more than 30 dB isolation ratio of laser radiation in the "eye-safe" wavelength range (1530-1620 nm) at the 5 and 20 kW power, respectively.

  9. Effect of oral calcium and calcium + fluoride treatments on mouse bone properties during suspension

    NASA Technical Reports Server (NTRS)

    Simske, S. J.; Luttges, M. W.; Allen, K. A.; Spooner, B. S. (Principal Investigator)

    1992-01-01

    The bone effects of oral dosages of calcium chloride with or without supplementary sodium fluoride were assessed in antiorthostatically suspended mice. Two calcium dosages were used to replace half (3.1 mM) or all(6.3 mM) of the dietary calcium lost due to reduced food intake by the suspended mice. Two groups of 6.3 mM CaCl2-treated mice were additionally treated with 0.25 or 2.5 mM NaF. The results indicate that supplementation of the mouse drinking water with calcium salts prevents bone changes induced by short-term suspension, while calcium salts in combination with fluoride are less effective as fluoride dosage increases. However, the calcium supplements change the relationship between the femur mechanical properties and the mineral composition of the bone. Because of this, it appears that oral calcium supplements are effective through a mechanism other than simple dietary supplementation and may indicate a dependence of bone consistency on systemic and local fluid conditions.

  10. Gum containing calcium fluoride reinforces enamel subsurface lesions in situ.

    PubMed

    Kitasako, Y; Sadr, A; Hamba, H; Ikeda, M; Tagami, J

    2012-04-01

    The aim of this study was to assess the effect of chewing gum containing phosphoryl oligosaccharides of calcium (POs-Ca) and a low concentration of fluoride (F) on the hardness of enamel subsurface lesions, utilizing a double-blind, randomized, and controlled in situ model. Fifteen individuals wore removable lingual appliances with 3 bovine-enamel insets containing subsurface demineralized lesions. Three times a day for 14 days, they chewed one of the 3 chewing gums (placebo, POs-Ca, POs-Ca+F). After the treatment period, cross-sectional mineral content, nanoindentation hardness, and fluoride ion mapping by time-of-flight secondary ion mass spectrometry (TOF-SIMS) were evaluated. Although there were no statistical differences in overall mineral content and hardness recovery rates between POs-Ca and POs-Ca+F subsurface lesions (p > 0.05), nanoindentation at 1-μm distance increments from the surface showed statistical differences in hardness recovery rate between POs-Ca and POs-Ca+F in the superficial 20-μm region (p < 0.05). Fluoride mapping revealed distribution of the ion up to 20 μm from the surface in the POs-Ca+F group. Nanoindentation and TOF-SIMS results highlighted the benefits of bioavailability of fluoride ion on reinforcement of the superficial zone of subsurface lesions in situ (NCT01377493).

  11. Antibacterial and physical properties of calcium-phosphate and calcium-fluoride nanocomposites with chlorhexidine

    PubMed Central

    Cheng, Lei; Weir, Michael D.; Xu, Hockin H. K.; Kraigsley, Alison M.; Lin, Nancy J.; Lin-Gibson, Sheng; Zhou, Xuedong

    2012-01-01

    Objectives Previous studies have developed calcium phosphate and fluoride releasing composites. Other studies have incorporated chlorhexidine (CHX) particles into dental composites. However, CHX has not been incorporated in calcium phosphate and fluoride composites. The objectives of this study were to develop nanocomposites containing amorphous calcium phosphate (ACP) or calcium fluoride (CaF2) nanoparticles and CHX particles, and investigate S. mutans biofilm formation and lactic acid production for the first time. Methods Chlorhexidine was frozen via liquid nitrogen and ground to obtain a particle size of 0.62 µm. Four nanocomposites were fabricated with fillers of: Nano ACP; nano ACP+10% CHX; nano CaF2; nano CaF2+10% CHX. Three commercial materials were tested as controls: A resin-modified glass ionomer, and two composites. S. mutans live/dead assay, colony-forming unit (CFU) counts, biofilm metabolic activity, and lactic acid were measured. Results Adding CHX fillers to ACP and CaF2 nanocomposites greatly increased their antimicrobial capability. ACP and CaF2 nanocomposites with CHX that were inoculated with S. mutans had a growth medium pH > 6.5 after 3 d, while the control commercial composites had a cariogenic pH of 4.2. Nanocomposites with CHX reduced the biofilm metabolic activity by 10–20 folds and reduced the acid production, compared to the controls. CFU on nanocomposites with CHX were three orders of magnitude less than that on commercial composite. Mechanical properties of nanocomposites with CHX matched a commercial composite without fluoride. Significance The novel calcium phosphate and fluoride nanocomposites could be rendered antibacterial with CHX to greatly reduce biofilm formation, acid production, CFU and metabolic activity. The antimicrobial and remineralizing nanocomposites with good mechanical properties may be promising for a wide range of tooth restorations with anti-caries capabilities. PMID:22317794

  12. Improved flexibility with grayscale fabrication of calcium fluoride homogenizers

    NASA Astrophysics Data System (ADS)

    Brown, Jeremiah; Brakhage, Peter; Simmons, Lamarr; Mueller, Ralf

    2012-03-01

    High quality and highly uniform illumination is a critical component for advanced lithography systems and wafer inspection tools. Homogenizer elements fabricated in calcium fluoride have demonstrated good performance for deep UV applications. Grayscale photolithography allows for the fabrication of single-sided micro lens array (MLA) elements with excellent optical performance. The MLA offers some significant advantages over crossed cylinders fabricated using grayscale photolithography processes, including the reduction in the number of fabrication steps and the added flexibility of manufacturing noncylindrical surface geometries. This research presentation reviews the fabrication process and compares grayscale crossed cylindrical arrays and MLAs in terms of their capabilities and performance.

  13. Intraoral evaluation of mineralization of cosmetic defects by a toothpaste containing calcium, fluoride, and sodium bicarbonate.

    PubMed

    Litkowski, Leonard J; Quinlan, Kathleen B; Ross, David R; Ghassemi, Annahita; Winston, Anthony; Charig, Andrew; Flickinger, Mark; Vorwerk, Linda

    2004-09-01

    New dual-phase fluoride toothpastes that contain soluble calcium, phosphate, and baking soda have recently been introduced into the market. These toothpastes are designed to fill in small surface defects in tooth enamel and thereby enhance tooth esthetics such as gloss. This two-part study was designed to assess these superficial mineralizing effects from using one of these products compared with an experimental calcium-containing, bicarbonate-free formulation and a conventional fluoride toothpaste using an intraoral model. Enamel specimens with 4 types of defects were mounted into an intraoral appliance and placed in the mouths of volunteers for 1 month. The four types of defects were whitening toothpaste abrasion, coarse abrasion, natural dimpling, and acid etching. Before and after intraoral exposure, scanning electron microscope photographs of the specimens were made. The surface microhardness of the acid-etched specimens also was determined. The volunteers brushed their specimens twice daily with one of three randomly assigned toothpastes. The toothpastes were a two-phase, calcium-containing, bicarbonate-based toothpaste; an experimental, two-phase, calcium-containing, bicarbonate-free toothpaste; and a conventional toothpaste. Only the calcium-containing toothpastes showed unequivocal signs of mineral deposition into surface defects, leading to smoothing of the enamel. All three products significantly increased the hardness of the etched enamel, presumably because of fluoride. However, only the two calcium-containing toothpastes gave significantly greater hardness increases than the conventional toothpaste; the specimens treated with a conventional toothpaste were indistinguishable from those treated with saliva. PMID:15645904

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

    PubMed

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

    2014-01-01

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

  15. Fluoride varnishes with calcium glycerophosphate: fluoride release and effect on in vitro enamel demineralization.

    PubMed

    Carvalho, Thiago Saads; Peters, Bianca Glerean; Rios, Daniela; Magalhães, Ana Carolina; Sampaio, Fabio Correia; Buzalaf, Marília Afonso Rabelo; Bönecker, Marcelo José Strazzeri

    2015-01-01

    The aims of this study were (1) to assess the amount of fluoride (F) released from varnishes containing calcium glycerophosphate (CaGP) and (2) to assess the effect of the experimental varnishes on in vitro demineralization. Six test groups using 5 varnishes: base varnish (no active ingredients); Duraphat® (2.26% NaF); Duofluorid® (5.63% NaF/CaF2); experimental varnish 1 (1% CaGP/5.63% NaF/CaF2); experimental varnish 2 (5% CaGP/5.63% NaF/CaF2); and no varnish were set up. In stage 1, 60 acrylic blocks were randomly distributed into 6 groups (n = 10). Then 300 µg of each varnish was applied to each block. The blocks were immersed in deionized water, which was changed after 1, 8, 12, 24, 48 and 72 hours. Fluoride concentration in the water was analyzed using a fluoride electrode. In stage 2, 60 bovine enamel samples were distributed into 6 groups (n = 10), and treated with 300 µg of the respective varnish. After 6 h the varnish was removed and the samples were subjected to a 7-day in vitro pH cycle (6 h demineralization/18 h remineralization per day). The demineralization was measured using surface hardness. The results showed that both experimental varnishes released more fluoride than Duofluorid® and Duraphat® (p < 0.05), but Duraphat® showed the best preventive effect by decreasing enamel hardness loss (p < 0.05). Therefore, we conclude that even though (1) the experimental varnishes containing CaGP released greater amounts of F, (2) they did not increase in the preventive effect against enamel demineralization. PMID:26176358

  16. Effect of calcium in model plaque on the anticaries activity of fluoride in vitro.

    PubMed

    Blake-Haskins, J C; Mellberg, J R; Snyder, C

    1992-08-01

    The uptake of calcium by a polysaccharide (agarose) gel used as a model for plaque from a two-step treatment (consisting of a calcium rinse followed by a fluoride treatment) and the effect of the deposited calcium in model plaque on caries lesion formation in enamel were determined. Calcium uptake was measured by treatment of the model plaques with [45Ca]-CaCl2 solutions with or without NaF. A two-step treatment consisting of calcium followed by fluoride produced a 100% increase in calcium content of model plaque, presumably due to the formation of CaF2, compared with a treatment with artificial saliva followed by calcium alone. The effects of these increased plaque minerals on caries lesion formation were studied by subjecting model-plaque-covered enamel blocks to a cyclic demineralization-remineralization treatment. Artificial-plaque-covered enamel blocks were treated daily with 180 ppm calcium for ten min, then 100 ppm fluoride for ten min, followed by demineralization for 16 h, and finally, remineralization for seven h and 40 min. After five days, the blocks were sectioned, and lesion formation was determined by microradiography-microdensitometry. Artificial plaque treated with a calcium rinse followed by a fluoride rinse reduced lesion size by 90%, compared with a 68% reduction by a fluoride rinse alone. When the experiment was repeated with a simulated pre-brush calcium rinse (180 ppm calcium) followed by a fluoride dentifrice suspension (110 ppm fluoride), lesion size was reduced by 46%, compared with a 32% reduction by the fluoride dentifrice suspension alone.

  17. Phytic acid plus calcium, but not phytic acid alone, decreases fluoride bioavailability in the rat

    SciTech Connect

    Cerklewski, F.L. )

    1991-03-15

    Results of in vitro studies have suggested that fluoride becomes insoluble when some soy-based infant formulas are diluted with fluoridated water because of the presence of phytate, added calcium or a combination of these factors. The present study was designed to test this hypothesis in vivo. Male albino rats were fed a purified diet containing phytic acid, calcium and fluoride for 4 weeks in a factorial design of treatments. Phytic acid was added to the diet by chemically reacting a phytic acid concentrate with casein prior to diet preparation to mimic a soy-protein. Food intake, weight gain and femur P were unaffected by dietary treatments. Both phytic acid and supplemental calcium alone had little or no effect upon fluoride uptake into either bone or teeth. The combination of phytic acid plus supplemental calcium, however, significantly increased % of fluoride intake found in the feces which was reflected in a significant decrease in fluoride concentration of femur, 2nd molar teeth and vertebrate bone. These results provide evidence that insoluble complex formation produced by a calcium and phytate interaction can explain reduced fluoride solubility in some soy-based infant formulas as well as decreased fluoride absorbability in vivo.

  18. Mechanism of Calcium Fluoride Acceleration for Vacuum Carbothermic Reduction of Magnesia

    NASA Astrophysics Data System (ADS)

    Jiang, Yun; Liu, Yu-qin; Ma, Hong-wen; Zhou, Wei-gong

    2016-04-01

    The use of a small amount of calcium fluoride as an additive greatly accelerated the reduction of magnesia during the preparation of magnesium from magnesia using the vacuum carbothermic reduction method. At 1573 K (1300 °C), the magnesia reaction rates of the samples with 1, 3, and 5 pct CaF2 were all approximately 26 pct, three times that of free CaF2, and they were arranged in order of the calcium fluoride weight percentages at 1673 K (1400 °C). The residues were analyzed using chemical analysis, XRD, SEM, EDS, and XRF. The possible acceleration mechanism was discussed. Calcium fluoride combined with magnesia and silicon dioxide to form a eutectic that melted as a channel to aid the solid-solid reaction between carbon and magnesia at approximately 1573 K (1300 °C). Calcium fluoride in the molten state offered free calcium ions and fluorine ions. Fluorine ions entered and distorted the magnesia crystal lattice. The structural strength and chemical stability of the magnesia crystal lattice decreased, which facilitated the magnesia reduction by carbon. Calcium ions were employed to generate the calcium and magnesium silicate. The easyly evaporating fluorides, including magnesium fluoride and silicon tetrafluoride, were regarded as the main reason for the loss of fluorine.

  19. 229Thorium-doped calcium fluoride for nuclear laser spectroscopy.

    PubMed

    Dessovic, P; Mohn, P; Jackson, R A; Winkler, G; Schreitl, M; Kazakov, G; Schumm, T

    2014-03-12

    The (229)thorium isotope presents an extremely low-energy isomer state of the nucleus which is expected around 7.8 eV, in the vacuum ultraviolet (VUV) regime. This unique system may bridge between atomic and nuclear physics, enabling coherent manipulation and precision spectroscopy of nuclear quantum states using laser light. It has been proposed to implant (229)thorium into VUV transparent crystal matrices to facilitate laser spectroscopy and possibly realize a solid-state nuclear clock. In this work, we validate the feasibility of this approach by computer modelling of thorium doping into calcium fluoride single crystals. Using atomistic modelling and full electronic structure calculations, we find a persistent large band gap and no additional electronic levels emerging in the middle of the gap due to the presence of the dopant, which should allow direct optical interrogation of the nuclear transition.Based on the electronic structure, we estimate the thorium nuclear quantum levels within the solid-state environment. Precision laser spectroscopy of these levels will allow the study of a broad range of crystal field effects, transferring Mössbauer spectroscopy into the optical regime.

  20. Birefringence simulation of annealed ingot of calcium fluoride single crystal

    NASA Astrophysics Data System (ADS)

    Ogino, H.; Miyazaki, N.; Mabuchi, T.; Nawata, T.

    2008-01-01

    We developed a method for simulating birefringence of an annealed ingot of calcium fluoride single crystal caused by the residual stress after annealing process. The method comprises the heat conduction analysis that provides the temperature distribution during the ingot annealing, the elastic thermal stress analysis using the assumption of the stress-free temperature that provides the residual stress after annealing, and the birefringence analysis of an annealed ingot induced by the residual stress. The finite element method was applied to the heat conduction analysis and the elastic thermal stress analysis. In these analyses, the temperature dependence of material properties and the crystal anisotropy were taken into account. In the birefringence analysis, the photoelastic effect gives the change of refractive indices, from which the optical path difference in the annealed ingot is calculated by the Jones calculus. The relation between the Jones calculus and the approximate method using the stress components averaged along the optical path is discussed theoretically. It is found that the result of the approximate method agrees very well with that of the Jones calculus in birefringence analysis. The distribution pattern of the optical path difference in the annealed ingot obtained from the present birefringence calculation methods agrees reasonably well with that of the experiment. The calculated values also agree reasonably well with those of the experiment, when a stress-free temperature is adequately selected.

  1. Effects of fluoride, calcium, and phosphate administration on mineralization in rats.

    PubMed

    Larsen, M J; Fejerskov, O; Jensen, S J

    1980-01-01

    Seven days before a fluoride injection of 20 mg sodium fluoride per kg body weight, 3-month-old rats grown on a standard pellet diet containing 0.8% calcium and 1.4% phosphate were given a diet of rice with only 0.025% calcium and 0.1% phosphate. Microradiographs of the continuously growing incisors showed a hypermineralized and subsequent hypomineralized zone. Blood analysis demonstrated a decrease and a subsequent reestablishment of plasma calcium concentration. In some experiments calcium and phosphate were administered to compensate the hypocalcemia which prevented the hypomineralized zone from arising. A delay of calcium and phosphate administration led to formation of a mineralized band within the hypomineralized zone. The results are discussed with reference to calcium homeostasis.

  2. The Effect of Salivary Calcium and Fluoride Toothpaste on the Formation of KOH-Soluble Fluoride: In Vitro Study

    PubMed Central

    Peroš, Kristina; Šutej, Ivana; Rošin-Grget, Kata

    2015-01-01

    Objective The aim of this in vitro preliminary study was to assess the effect of smokers’ saliva (assuming their higher calcium concentration) in combination with fluoridated toothpaste on the enamel uptake of alkali-soluble (KOH-soluble) fluoride. Materials and methods Four enamel slabs were cut from each of 14 impacted third molars and randomly assigned into 4 groups. Unstimulated saliva samples were collected from two age and sex matched volunteers. One of the samples was taken from a heavy smoker and the other sample was taken from a non-smoker. Two groups (A and B) were shaken in saliva (A in smoker's saliva, B in nonsmoker's saliva) for 5 min and then shaken for 3 min in a toothpaste/deionized water slurry (1:3 w/w). One of the groups (group C) received no saliva treatment and was only shaken in toothpaste slurry for 3 min. The treatment was repeated after a 6-hour period. One of the groups (D) served as a control group with no treatment. Results Calcium concentration in the smoker’s saliva was higher than in the nonsmoker’s saliva. The enamel uptake of KOH-soluble fluoride in group A was significantly higher than that in the other two treatment groups, B and C. The enamel uptake of KOH-soluble fluoride in all 3 groups was statistically different from that in the control group. Conclusion These results demonstrate that saliva collected from a heavy smoker, which had higher salivary calcium concentration, enhances enamel uptake of alkali-soluble fluoride and encourages us to conduct a large-scale study. PMID:27688406

  3. [Natural fluorides. The distinction between technically produced and naturally occurring fluorides in caries prophylaxis].

    PubMed

    Newesely, H

    1977-06-01

    In the controversial discussion of the bio-availability of fluoride in caries prophylaxis by fluoridation, fluorides coming from the geochemical circulation to the biochemical circulation are sometimes differentiated from synthetic fluorides introduced into fluoride medication. The question as to whether such a differentiation is essential can be answered from the physical-chemical point of view. This requires a wide field of scientific research starting with geochemistry and the knowledge of fluoride deposits, sedimentology, hydrology, technology of inorganic and organic fluorine compounds, thermodynamics of dissolved fluorides, up to biocrystallography and biochemistry of fluorine. PMID:267571

  4. Effect of Fluoride, Casein Phosphopeptide–Amorphous Calcium Phosphate and Casein Phosphopeptide–Amorphous Calcium Phosphate Fluoride on Enamel Surface Microhardness After Microabrasion: An in Vitro Study

    PubMed Central

    Ahmadi Zenouz, Ghazaleh; Ezoji, Fariba; Khafri, Soraya

    2015-01-01

    Objectives: This study aimed to assess the effect of applying casein phosphopeptide– amorphous calcium phosphate (CPP-ACP) paste, casein phosphopeptide–amorphous calcium phosphate fluoride (CPP-ACPF) paste and sodium fluoride gel on surface microhardness of enamel after microabrasion. Materials and Methods: Thirty freshly extracted human premolars were selected. All samples were subjected to hardness indentations made with the Vickers hardness machine and the average value was recorded as the initial surface microhardness. The specimens were then randomly divided into three groups (n=10) of CPP-ACPF, fluoride and CPPACP. The teeth were micro-abraded with Opalustre. Microhardness test was performed to assess the post-abrasion hardness. Three remineralization modalities were performed on samples of each group. The enamel surface microhardness measurements were performed. To compare the difference between groups, the rehardening and softening values were defined. One-way ANOVA and Tukey’s post hoc test at a significance level of 5% were used for statistical analysis. Results: The mean microhardness value (MMV) had a significant decrease after microabrasion from baseline. The MMV had a significant increase after remineralization in all groups. The MMV of CPP-ACPF group was significantly more than that of fluoride group (P=0.027). The rehardening value of fluoride group was significantly more than that of other groups (P<0.001). Conclusion: All the remineralizing agents were effective for rehardening the enamel after microabrasion. The CPP-ACP and CPP-ACPF pastes are effective, but to a lesser extent than neutral sodium fluoride gel in remineralizing enamel surface. Incorporation of fluoride to CPP-ACP formulation does not provide any additional remineralizing potential. PMID:27252753

  5. Preparation and optimization of calcium fluoride particles for dental applications.

    PubMed

    Koeser, Joachim; Carvalho, Thiago Saads; Pieles, Uwe; Lussi, Adrian

    2014-07-01

    Fluorides are used in dental care due to their beneficial effect in tooth enamel de-/remineralization cycles. To achieve a desired constant supply of soluble fluorides in the oral cavity, different approaches have been followed. Here we present results on the preparation of CaF2 particles and their characterization with respect to a potential application as enamel associated fluoride releasing reservoirs. CaF2 particles were synthesized by precipitation from soluble NaF and CaCl2 salt solutions of defined concentrations and their morphology analyzed by scanning electron microscopy. CaF2 particles with defined sizes and shapes could be synthesized by adjusting the concentrations of the precursor salt solutions. Such particles interacted with enamel surfaces when applied at fluoride concentrations correlating to typical dental care products. Fluoride release from the synthesized CaF2 particles was observed to be largely influenced by the concentration of phosphate in the solution. Physiological solutions with phosphate concentration similar to saliva (3.5 mM) reduced the fluoride release from pure CaF2 particles by a factor of 10-20 × as compared to phosphate free buffer solutions. Fluoride release was even lower in human saliva. The fluoride release could be increased by the addition of phosphate in substoichiometric amounts during CaF2 particle synthesis. The presented results demonstrate that the morphology and fluoride release characteristics of CaF2 particles can be tuned and provide evidence of the suitability of synthetic CaF2 particles as enamel associated fluoride reservoirs.

  6. Apatite precipitation on a novel fast-setting calcium silicate cement containing fluoride

    PubMed Central

    Ranjkesh, Bahram; Chevallier, Jacques; Salehi, Hamideh; Cuisinier, Frédéric; Isidor, Flemming; Løvschall, Henrik

    2016-01-01

    Abstract Aim: Calcium silicate cements are widely used in endodontics. Novel fast-setting calcium silicate cement with fluoride (Protooth) has been developed for potential applications in teeth crowns including cavity lining and cementation. Objective: To evaluate the surface apatite-forming ability of Protooth compositions as a function of fluoride content and immersion time in phosphate-buffered saline (PBS). Material and methods: Three cement compositions were tested: Protooth (3.5% fluoride and 10% radiocontrast), ultrafast Protooth (3.5% fluoride and 20% radiocontrast), and high fluoride Protooth (15% fluoride and 25% radiocontrast). Powders were cap-mixed with liquid, filled to the molds and immersed in PBS. Scanning electron microscopy, energy dispersive X-ray analysis, and Raman spectroscopy were used to characterize the precipitations morphology and composition after 1, 7, 28, and 56 days. Apatite/belite Raman peak height indicated the apatite thickness. Results: Spherical calcium phosphate precipitations with acicular crystallites were formed after 1-day immersion in PBS and Raman spectra disclosed the phosphate band at 965 cm−1, supporting the apatite formation over Protooth compositions. The apatite deposition continued and more voluminous precipitations were observed after 56 days over the surface of all cements. Raman bands suggested the formation of β-type carbonated apatite over Protooth compositions. High fluoride Protooth showed the most compact deposition with significantly higher apatite/belite ratio compared to Protooth and ultrafast Protooth after 28 and 56 days. Conclusions: Calcium phosphate precipitations (apatite) were formed over Protooth compositions after immersion in PBS with increasing apatite formation as a function of time. High fluoride Protooth exhibited thicker apatite deposition. PMID:27335901

  7. Calcium fluoride windows for high-energy chemical lasers

    NASA Astrophysics Data System (ADS)

    Klein, Claude A.

    2006-10-01

    The development of high-energy lasers requires optical windows capable of handling megajoule beam energies without compromising the system's performance. Calcium fluoride (CaF2) has been identified as a prime candidate for windows operating at chemical laser wavelengths due to very low bulk absorption and exceptionally small thermal lensing coefficients; it is, however, vulnerable to structural failure owing to poor mechanical strength characteristics and a large thermal stress factor. It is, therefore, essential to properly assess the ultimate potential of this material, which we attempt to do here in the following manner: (a) We assemble reliable numbers for all pertinent properties of (111)-oriented CaF2 single crystals and polycrystalline isotropic aggregates (PIAs), such as fusion-cast CaF2, which requires addressing issues relating to the elastic properties, the stress-optic coefficients, and the flexural strength. (b) We provide correct analytical expressions for evaluating the impact of pressure- and beam-induced effects on wave-front phase distortions and mechanical failure modes, taking advantage of a previous investigation [J. Appl. Phys. 98, 043103 (2005)]. (c) We perform detailed calculations on "model" windows made of either (111)CaF2 or (PIA )CaF2 that transmit optimally truncated Gaussian beams at wavelengths of 1.15 and 3.39μm, for run times such that lateral heat conduction and surface cooling can be ignored. Our main conlusions are as follows: (a) With CaF2 windows thermal lensing, as measured in terms of the Strehl ratio and on assuming coating absorptances of no more than 3×10-5, is of no consequence in the sense that catastrophic failure may occur at fluence levels way below the threshold for optical distortion. (b) Evidence of a poor Weibull shape factor (m ≃3.5) degrades the design safety margins, which requires operating at peak intensities of no more than 100kW/cm2 to achieve optimum on-target fluences. (c) Regarding the issue of (111

  8. Loss on drying, calcium concentration and pH of fluoride dentifrices

    PubMed Central

    Brito, Arella Cristina Muniz; Dantas, Lívia Rocha; De Brito, André Luiz Fiquene; Muniz, Ana Cristina Silva; Ramos, Ianny Alves; Cardoso, Andreia Medeiros Rodrigues; Xavier, Alidianne Fábia Cabral; Cavalcanti, Alessandro Leite

    2015-01-01

    Introduction: Fluoride dentifrices containing calcium carbonate have advantages such as control of dental plaque and progression of dental caries, also contributing to oral hygiene, represent most dentifrices marketed in Brazil. Aim: To evaluate the physicochemical properties of seven fluoride dentifrices containing calcium carbonate in relation to hydrogen potential (pH), loss on drying and calcium concentration. Materials and Methods: Data collection was performed using the potentiometric method for pH ranges, gravimetric analysis for loss on drying and atomic absorption spectrometry for the concentration of calcium ions. All tests were performed in triplicate and the analysis was performed entirely at random according to one-way analysis of variance at 5% significance level. Results: The pH values were alkaline and ranged from 8.67 (Oral-B 123®) to 10.03 (Colgate Máxima Proteção Anticáries®). The results of loss on drying ranged from 33.81% (Oral-B 123®) to 61.13% (Close Up®), with significant differences between brands tested. In relation to the calcium content, the highest and lowest concentrations were found in dentifrices Even® (155.55 g/kg) and Colgate Ultra Branco® (129 g/kg), respectively, with significant difference (P < 0.05). Conclusion: Fluoride dentifrices analyzed showed alkaline pH and high levels of loss on drying and calcium concentration. However, these physicochemical characteristics differed according to the different brands tested. PMID:25821380

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

    SciTech Connect

    Yoder Jr, Graydon L; Heatherly, Dennis Wayne; Williams, David F; Elkassabgi, Yousri M.; Caja, Joseph; Caja, Mario; Jordan, John; Salinas, Roberto

    2014-04-01

    A small molten fluoride salt experiment has been constructed and tested to develop experimental techniques for application in liquid fluoride salt systems. There were five major objectives in developing this test apparatus: Allow visual observation of the salt during testing (how can lighting be introduced, how can pictures be taken, what can be seen) Determine if IR photography can be used to examine components submerged in the salt Determine if the experimental configuration provides salt velocity sufficient for collection of corrosion data for future experimentation Determine if a laser Doppler velocimeter can be used to quantify salt velocities. Acquire natural circulation heat transfer data in fluoride salt at temperatures up to 700oC All of these objectives were successfully achieved during testing with the exception of the fourth: acquiring velocity data using the laser Doppler velocimeter. This paper describes the experiment and experimental techniques used, and presents data taken during natural circulation testing.

  10. Fluoride

    MedlinePlus

    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 ...

  11. Physiologic Conditions Affect Toxicity of Ingested Industrial Fluoride

    PubMed Central

    Sauerheber, Richard

    2013-01-01

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

  12. Study on Treatment of acidic and highly concentrated fluoride waste water using calcium oxide-calcium chloride

    NASA Astrophysics Data System (ADS)

    Ren, T.; Gao, X. R.; Zheng, T.; Wang, P.

    2016-08-01

    There are problems with treating acidic waste water containing high concentration fluorine by chemical precipitation, including the low sludge setting velocity and the high difficulty of reaching the criterion. In Heilongjiang province, a graphite factory producing high-purity graphite generates acidic waste water with a high concentration of fluorine. In this paper, the effect of removals on the concentration of fluoride with the combined treatment of calcium oxide and calcium chloride were discussed with regard to acid waste water. The study improved the sludge characteristics by using polyacrylamide (PAM) and polymeric aluminum chloride (PAC). The effect of different coagulants on sludge was evaluated by the sludge settlement ratio (SV), sludge volume index (SVI) and sludge moisture content. The results showed that the optimal combination for 100 ml waste water was calcium oxide addition amount of 14 g, a calcium chloride addition amount of 2.5 g, a PAM addition amount of 350 mg/L, and the effluent fluoride concentration was below 6 mg/L. PAM significantly improved the sludge settling velocity. The sludge settlement ratio reduced from 87.6% to 60%. The process for wastewater treatment was easily operated and involved low expenditure.

  13. Chemical and X-ray analysis of fluoride, phosphorus, and calcium in human foetal blood and hard tissues.

    PubMed

    Montherrat-Carret, L; Perrat-Mabilon, B; Barbey, E; Bouloc, R; Boivin, G; Michelet, A; Magloire, H

    1996-12-01

    To evaluate the beneficial effect of prenatal fluoride supplementation, the presence of fluoride in hard tissues in two populations of human foetuses coming from fluoridated (> or = 0.7 parts/10(6) F in drinking water) and non-fluoridated areas (< or = 0.1 parts/10(6) F in drinking water) were compared by chemical analysis and X-ray microanalysis. The fluoride concentrations measured in maternal and venous cord blood confirmed that placental transfer of fluoride was passive when fluoride intake was low. Total fluoride contents of tooth germs and mandibular bone appeared to increase with fluoride level in drinking water. However, these concentrations were too low to be detected by X-ray microanalysis. Phosphorus and calcium total contents were identical in mandibular and femoral bone of both populations. In incisor germs, phosphorus and calcium concentrations in enamel and dentine close to the amelodentinal junction did not differ significantly between the two populations. It is suggested that the low fluoride concentrations in enamel and dentine formed in utero would not have a significant effect on acid solubility.

  14. In Vitro Properties of Orthodontic Adhesives with Fluoride or Amorphous Calcium Phosphate

    PubMed Central

    Chow, Clara Ka Wai; Wu, Christine D.; Evans, Carla A.

    2011-01-01

    This in vitro study evaluated the efficacy of orthodontic adhesives with fluoride or amorphous calcium phosphate (ACP) in reducing bacterial adhesion and enamel demineralization. Forty human premolars each sectioned buccolingually into three parts were bracketed with control resin (Transbond XT) or adhesives containing ACP (Aegis Ortho) or fluoride (QuickCure). Artificial lesions induced by pH cycling were examined by X-ray photoelectron spectrophotometry (XPS) and polarized light microscopy (PLM). After 28 days, Aegis Ortho demonstrated the lowest calcium and phosphorous content by XPS analysis. After 42 days, reductions in lesion depth areas were 23.6% for Quick Cure and 20.3% for Aegis Ortho (P < 0.05). In the presence of 1% sucrose, adhesion of Streptococcus mutans to Aegis Ortho and Quick Cure was reduced by 41.8% and 37.7% (P < 0.05) as compared to Transbond XT. Composites containing ACP or fluoride reduced bacterial adherence and lesion formation as compared to a composite without ACP or fluoride. PMID:21912546

  15. Report on the Study of Radiation Damage in Calcium Fluoride and Magnesium Fluoride Crystals for use in Excimer Laser Applications

    SciTech Connect

    None, None

    1999-10-04

    A study was performed to investigate the effects of radiation damage in calcium fluoride and magnesium fluoride crystals caused by gamma rays and UV photons from excimer lasers. The purpose was to study and correlate the damage caused by these two different mechanisms in various types of material used for fabricating optical elements in high power excimer lasers and lens systems of lithography tools. These optical systems are easily damaged by the laser itself, and it is necessary to use only the most radiation resistant materials for certain key elements. It was found that a clear correlation exists between the, radiation induced damage caused by high energy gamma rays and that produced by UV photons from the excimer laser. This correlation allows a simple procedure to be developed to select the most radiation resistant material at the ingot level, which would be later used to fabricate various components of the optical system. This avoids incurring the additional cost of fabricating actual optical elements with material that would later be damaged under prolonged use. The result of this screening procedure can result in a considerable savings in the overall cost of the lens and laser system.

  16. Effects of acute sodium fluoride exposure on kidney function, water homeostasis, and renal handling of calcium and inorganic phosphate.

    PubMed

    Santoyo-Sanchez, Mitzi Paola; del Carmen Silva-Lucero, Maria; Arreola-Mendoza, Laura; Barbier, Olivier Christophe

    2013-06-01

    Fluoride compounds are abundant and widely distributed in the environment at a variety of concentrations. Further, fluoride induces toxic effects in target organs such as the liver and kidney. In this study, we performed an early analysis of renal function using a clearance technique in Wistar rats acutely exposed to fluoride at a plasma concentration of 0.625 μg/ml. Our results revealed that fluoride, at a concentration close to the concentration present in the serum after environmental exposure, induced a significant tubular dysfunction, resulting in diluted urine, impaired protein reabsorption, and increased calcium and phosphate urinary excretion. Our work demonstrates that even acute exposures to low concentrations of NaF may induce renal damage and confirms that, after exposure, the kidney participates directly in the calcium and phosphate deficiencies observed in fluoride-exposed populations.

  17. Combinatorial incorporation of fluoride and cobalt ions into calcium phosphates to stimulate osteogenesis and angiogenesis.

    PubMed

    Birgani, Zeinab Tahmasebi; Gharraee, Nazli; Malhotra, Angad; van Blitterswijk, Clemens A; Habibovic, Pamela

    2016-02-29

    Bone healing requires two critical mechanisms, angiogenesis and osteogenesis. In order to improve bone graft substitutes, both mechanisms should be addressed simultaneously. While the individual effects of various bioinorganics have been studied, an understanding of the combinatorial effects is lacking. Cobalt and fluoride ions, in appropriate concentrations, are known to individually favor the vascularization and mineralization processes, respectively. This study investigated the potential of using a combination of fluoride and cobalt ions to simultaneously promote osteogenesis and angiogenesis in human mesenchymal stromal cells (hMSCs). Using a two-step biomimetic method, wells of tissue culture plates were coated with a calcium phosphate (CaP) layer without or with the incorporation of cobalt, fluoride, or both. In parallel, hMSCs were cultured on uncoated well plates, and cultured with cobalt and/or fluoride ions within the media. The results revealed that cobalt ions increased the expression of angiogenic markers, with the effects being stronger when the ions were added as a dissolved salt in cell medium as compared to incorporation into CaP. Cobalt ions generally suppressed the ALP activity, the expression of osteogenic genes, and the level of mineralization, regardless of delivery method. Fluoride ions, individually or in combination with cobalt, significantly increased the expression of many of the selected osteogenic markers, as well as mineral deposition. This study demonstrates an approach to simultaneously target the two essential mechanisms in bone healing: angiogenesis and osteogenesis. The incorporation of cobalt and fluoride into CaPs is a promising method to improve the biological performance of fully synthetic bone graft substitutes.

  18. Combinatorial incorporation of fluoride and cobalt ions into calcium phosphates to stimulate osteogenesis and angiogenesis.

    PubMed

    Birgani, Zeinab Tahmasebi; Gharraee, Nazli; Malhotra, Angad; van Blitterswijk, Clemens A; Habibovic, Pamela

    2016-02-01

    Bone healing requires two critical mechanisms, angiogenesis and osteogenesis. In order to improve bone graft substitutes, both mechanisms should be addressed simultaneously. While the individual effects of various bioinorganics have been studied, an understanding of the combinatorial effects is lacking. Cobalt and fluoride ions, in appropriate concentrations, are known to individually favor the vascularization and mineralization processes, respectively. This study investigated the potential of using a combination of fluoride and cobalt ions to simultaneously promote osteogenesis and angiogenesis in human mesenchymal stromal cells (hMSCs). Using a two-step biomimetic method, wells of tissue culture plates were coated with a calcium phosphate (CaP) layer without or with the incorporation of cobalt, fluoride, or both. In parallel, hMSCs were cultured on uncoated well plates, and cultured with cobalt and/or fluoride ions within the media. The results revealed that cobalt ions increased the expression of angiogenic markers, with the effects being stronger when the ions were added as a dissolved salt in cell medium as compared to incorporation into CaP. Cobalt ions generally suppressed the ALP activity, the expression of osteogenic genes, and the level of mineralization, regardless of delivery method. Fluoride ions, individually or in combination with cobalt, significantly increased the expression of many of the selected osteogenic markers, as well as mineral deposition. This study demonstrates an approach to simultaneously target the two essential mechanisms in bone healing: angiogenesis and osteogenesis. The incorporation of cobalt and fluoride into CaPs is a promising method to improve the biological performance of fully synthetic bone graft substitutes. PMID:26929187

  19. Study of changes in phosphate, calcium and fluoride ions in plaque and saliva after the administration of a fluoride mouth rinse.

    PubMed

    Poureslami, H R; Torkzadeh, M; Sefadini, M R

    2007-01-01

    In this study, the effects of 0.2% sodium fluoride mouthwash solution on calcium, phosphate and fluoride ion contents of saliva and microbial plaque was assessed. Fourteen volunteer students (7-12 years of age) of a boarding educational centre in Kerman City (Iran) were selected and under defined conditions, their saliva and plaque samples were collected. The concentrations of fluoride, calcium and phosphate ions of the samples were determined, and after 14 days, under the same conditions, the students were asked to rinse their mouth with 0.2% sodium fluoride mouthwash solution. The second set of saliva and plaque samples were collected and the concentrations of the ions were determined. Data was analyzed using paired t-test and the results were presented as tables. P < 0.05 was considered as statistically significant. After using 0.2% sodium fluoride mouthwash solution, a significant increase was observed in the F 2 ion concentration both plaque ( P P < 0.000) of all the studied subjects, while the concentration of phosphate decreased in both saliva and plaque; however, this decrease was significant only in plaque ( P < 0.01). The calcium ion concentration decreased in both plaque and saliva; however, in none of them, the decrease was significant ( P> 0.09 and P> 0.2, respectively).

  20. Fluoride-assisted activation of calcium carbide: a simple method for the ethynylation of aldehydes and ketones.

    PubMed

    Hosseini, Abolfazl; Seidel, Daniel; Miska, Andreas; Schreiner, Peter R

    2015-06-01

    The fluoride-assisted ethynylation of ketones and aldehydes is described using commercially available calcium carbide with typically 5 mol % of TBAF·3H2O as the catalyst in DMSO. Activation of calcium carbide by fluoride is thought to generate an acetylide "ate"-complex that readily adds to carbonyl groups. Aliphatic aldehydes and ketones generally provide high yields, whereas aromatic carbonyls afford propargylic alcohols with moderate to good yields. The use of calcium carbide as a safe acetylide ion source along with economic amounts of TBAF·3H2O make this procedure a cheap and operationally simple method for the preparation of propargylic alcohols.

  1. Efficacy of calcium- and fluoride-containing materials for the remineralization of primary teeth with early enamel lesion.

    PubMed

    Memarpour, Mahtab; Soltanimehr, Elham; Sattarahmady, Naghmeh

    2015-09-01

    The aim of the study was to determine the efficacy of different products containing fluoride, calcium and phosphate for enamel remineralization in eroded primary teeth. A total of 90 sound primary canine teeth were randomly divided into 5 groups of 18 teeth each: 1) control (polished enamel), 2) 5% DuraShield sodium fluoride varnish, 3) 500 ppm fluoridated toothpaste, 4) casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) cream, and 5) Clinpro White varnish containing functionalized tri-calcium phosphate (fTCP). Enamel microhardness (EMH) was measured in all samples before and after demineralization and after 28 days of remineralization. Also 8 samples in groups 2 to 5 and four samples of sound and demineralized enamel were examined with atomic force microscopy (AFM). All data were analyzed with one-way ANOVA (p<0.05). Mean microhardness of demineralized enamel was significantly lower than in enamel at baseline (p<0.001). Remineralization significantly increased microharness in groups 2 to 5 compared to the control group (p<0.001). Percent EMH after remineralization with CPP-ACP was significantly higher than after fTCP (p=0.029), toothpaste (p< 0.001) or fluoride varnish (p<0.001); however, there was no significant difference between toothpaste and fluoride varnish (p=0.062). Microhardness increased more after fTCP treatment than after treatment with sodium fluoride varnish (p<0.001) or fluoridated toothpaste (p=0.045). AFM images showed that enamel roughness decreased most after treatment with fTCP, followed by CPP-ACP, toothpaste and fluoride varnish. The efficacy of CPP-ACP cream for remineralizing eroded enamel was greater than fluoride toothpaste, fluoride varnish or fTCP varnish. PMID:26179280

  2. Efficacy of calcium- and fluoride-containing materials for the remineralization of primary teeth with early enamel lesion.

    PubMed

    Memarpour, Mahtab; Soltanimehr, Elham; Sattarahmady, Naghmeh

    2015-09-01

    The aim of the study was to determine the efficacy of different products containing fluoride, calcium and phosphate for enamel remineralization in eroded primary teeth. A total of 90 sound primary canine teeth were randomly divided into 5 groups of 18 teeth each: 1) control (polished enamel), 2) 5% DuraShield sodium fluoride varnish, 3) 500 ppm fluoridated toothpaste, 4) casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) cream, and 5) Clinpro White varnish containing functionalized tri-calcium phosphate (fTCP). Enamel microhardness (EMH) was measured in all samples before and after demineralization and after 28 days of remineralization. Also 8 samples in groups 2 to 5 and four samples of sound and demineralized enamel were examined with atomic force microscopy (AFM). All data were analyzed with one-way ANOVA (p<0.05). Mean microhardness of demineralized enamel was significantly lower than in enamel at baseline (p<0.001). Remineralization significantly increased microharness in groups 2 to 5 compared to the control group (p<0.001). Percent EMH after remineralization with CPP-ACP was significantly higher than after fTCP (p=0.029), toothpaste (p< 0.001) or fluoride varnish (p<0.001); however, there was no significant difference between toothpaste and fluoride varnish (p=0.062). Microhardness increased more after fTCP treatment than after treatment with sodium fluoride varnish (p<0.001) or fluoridated toothpaste (p=0.045). AFM images showed that enamel roughness decreased most after treatment with fTCP, followed by CPP-ACP, toothpaste and fluoride varnish. The efficacy of CPP-ACP cream for remineralizing eroded enamel was greater than fluoride toothpaste, fluoride varnish or fTCP varnish.

  3. Erosion protection by calcium lactate/sodium fluoride rinses under different salivary flows in vitro.

    PubMed

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

    2014-01-01

    This study investigated the effect of a calcium lactate prerinse on sodium fluoride protection in an in vitro erosion-remineralization model simulating two different salivary flow rates. Enamel and dentin specimens were randomly assigned to 6 groups (n = 8), according to the combination between rinse treatments - deionized water (DIW), 12 mM NaF (NaF) or 150 mM calcium lactate followed by NaF (CaL + NaF) - and unstimulated salivary flow rates - 0.5 or 0.05 ml/min - simulating normal and low salivary flow rates, respectively. The specimens were placed into custom-made devices, creating a sealed chamber on the specimen surface connected to a peristaltic pump. Citric acid was injected into the chamber for 2 min, followed by artificial saliva (0.5 or 0.05 ml/min) for 60 min. This cycle was repeated 4×/day for 3 days. Rinse treatments were performed daily 30 min after the 1st and 4th erosive challenges, for 1 min each time. Surface loss was determined by optical profilometry. KOH-soluble fluoride and structurally bound fluoride were determined in specimens at the end of the experiment. Data were analyzed by 2-way ANOVA and Tukey tests (α = 0.05). NaF and CaL + NaF exhibited significantly lower enamel and dentin loss than DIW, with no difference between them for normal flow conditions. The low salivary flow rate increased enamel and dentin loss, except for CaL + NaF, which presented overall higher KOH-soluble and structurally bound fluoride levels. The results suggest that the NaF rinse was able to reduce erosion progression. Although the CaL prerinse considerably increased F availability, it enhanced NaF protection against dentin erosion only under hyposalivatory conditions.

  4. Bleaching gels containing calcium and fluoride: effect on enamel erosion susceptibility.

    PubMed

    Borges, Alessandra B; Torres, Carlos R G; de Souza, Paulo A B; Caneppele, Taciana M F; Santos, Luciana F T F; Magalhães, Ana Carolina

    2012-01-01

    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. PMID:23193404

  5. In vitro enamel remineralization by low-fluoride toothpaste with calcium citrate and sodium trimetaphosphate.

    PubMed

    Hirata, Edo; Danelon, Marcelle; Freire, Isabelle Rodrigues; Delbem, Alberto Carlos Botazzo

    2013-01-01

    The objective of this study was to evaluate in vitro the effect of a low fluoride toothpaste (450 µgF/g, NaF) combined with calcium citrate (Cacit) and sodium trimetaphosphate (TMP) on enamel remineralization. Bovine enamel blocks had the enamel surface polished sequentially to determine the surface hardness. After production of artificial carious lesions, the blocks selected by their surface hardness were submitted to remineralization pH cycling and daily treatment with dentifrice suspensions (diluted in deionized water or artificial saliva): placebo, 275, 450, 550 and 1,100 µgF/g and commercial dentifrice (positive control, 1,100 µgF/g). Finally, the surface and cross-section hardness was determined for calculating the change of surface hardness (%SH) and mineral content (%∆Z). Fluoride in enamel was also determined. The data from %SH, %∆Z and fluoride were subjected to two-way analysis of variance followed by Student-Newman-Keuls's test (p<0.05). The mineral gain (%SH and %∆Z) was higher for toothpastes diluted in saliva (p<0.05), except for the 450 µgF/g dentifrice with Cacit/TMP (p>0.05). The 450 Cacit/TMP toothpaste and the positive control showed similar results (p>0.05) when diluted in water. A dose-response was observed between fluoride concentration in toothpastes and fluoride present in enamel, regardless of dilution. It was concluded that it is possible to enhance the remineralization capacity of low F concentration toothpaste by of organic (Cacit) and inorganic (TMP) compounds with affinity to hydroxyapatite.

  6. In vitro enamel remineralization by low-fluoride toothpaste with calcium citrate and sodium trimetaphosphate.

    PubMed

    Hirata, Edo; Danelon, Marcelle; Freire, Isabelle Rodrigues; Delbem, Alberto Carlos Botazzo

    2013-01-01

    The objective of this study was to evaluate in vitro the effect of a low fluoride toothpaste (450 µgF/g, NaF) combined with calcium citrate (Cacit) and sodium trimetaphosphate (TMP) on enamel remineralization. Bovine enamel blocks had the enamel surface polished sequentially to determine the surface hardness. After production of artificial carious lesions, the blocks selected by their surface hardness were submitted to remineralization pH cycling and daily treatment with dentifrice suspensions (diluted in deionized water or artificial saliva): placebo, 275, 450, 550 and 1,100 µgF/g and commercial dentifrice (positive control, 1,100 µgF/g). Finally, the surface and cross-section hardness was determined for calculating the change of surface hardness (%SH) and mineral content (%∆Z). Fluoride in enamel was also determined. The data from %SH, %∆Z and fluoride were subjected to two-way analysis of variance followed by Student-Newman-Keuls's test (p<0.05). The mineral gain (%SH and %∆Z) was higher for toothpastes diluted in saliva (p<0.05), except for the 450 µgF/g dentifrice with Cacit/TMP (p>0.05). The 450 Cacit/TMP toothpaste and the positive control showed similar results (p>0.05) when diluted in water. A dose-response was observed between fluoride concentration in toothpastes and fluoride present in enamel, regardless of dilution. It was concluded that it is possible to enhance the remineralization capacity of low F concentration toothpaste by of organic (Cacit) and inorganic (TMP) compounds with affinity to hydroxyapatite. PMID:23969915

  7. Effect of Fluoride on the Morphology of Calcium Phosphate Crystals Grown on Acid-Etched Human Enamel

    PubMed Central

    Fan, Y.; Sun, Z.; Moradian-Oldak, J.

    2009-01-01

    The aim of this study was to examine the effect of fluoride ion concentration on the morphology of calcium phosphate crystals grown on acid-etched enamel as a model for tooth enamel erosion. Samples were immersed in calcification solution for 16 h and changes in crystal morphology were monitored by field emission scanning electron microscopy. Without fluoride, plate-like octacalcium phosphate crystals (20 nm thick, 2–10 μm wide) were formed. With 1–10 mg/l fluoride, arrays of denser needle-like nanocrystals (20–30 nm wide, >500 nm in length) were formed. We conclude that there is a minimal fluoride concentration (1 mg/l) that dramatically affects the morphology of calcium phosphate crystals grown on etched enamel in vitro. PMID:19321991

  8. Treatment of Volatile Organic Compounds with Mesoporous Materials Prepared from Calcium Fluoride Sludge.

    PubMed

    Kang, Sv-Yuan; Tsai, Hsiao-Hsin; Nguyen, Nhat-Thien; Chang, Chang-Tang; Tseng, Chao-Heng

    2016-02-01

    Large amount of calcium fluoride sludge was generated by semiconductor industry every year. It also needs high requirement of fuel consumption using rotor concentrator and thermal oxidizer to treat VOCs. The mesoporous catalyst prepared by calcium fluoride sludge was used for VOCs treatment in this study. Acetone is a kind of solvent and used in a large number of laboratories and factories. The serious problems will be caused when it exposed to the environmental. Economic and practical technology is needed to eliminate this kind of hazardous air pollutant. In this research, the adsorption of acetone was tested with CF-MCM (mesoporous silica materials synthesized from calcium fluoride). The raw material was mixed with cationic cetyltrimethyl ammonium bromide (CTAB) surfactants, firstly. The prepared mesoporous silica materials were characterized by nitrogen adsorption and desorption analysis, transmission electron microscope (TEM), scanning electron microscopy (SEM), X-ray powder diffractometer (XRPD) and Fourier transform infrared spectroscopy (FTIR). The results showed that the surface area, large pore volume and pore diameter could be up to 862 m2 g(-1), 0.57 cm3 g(-1) and 2.9 nm, respectively. The crystal patterns of CF-MCM were similar with MCM-41 from TEM image. The adsorption capacity of acetone with CF-MCM was 118, 190, 194 and 201 mg g(-1), respectively, under 500, 1000, 1500 and 2000 ppm. Furthermore, the adsorption capacity of MCM-41 and CF-MCM was almost the same. The effects of operation parameters, such as contact time and mixture concentration, on the performance of CF-MCM were also discussed in this study. PMID:27433709

  9. A scanning electron microscope investigation of calcium fluoride-like material deposited during topical fluoride exposure on sound human enamel in vitro.

    PubMed

    Cruz, R A; Rolla, G

    1994-10-01

    1. The morphological aspects of globules deposited in vitro when a NaF solution is applied to sound human enamel were studied by scanning electron microscopy. 2. Particles, presumably of calcium fluoride-like material, formed on the surfaces of an unerupted tooth and consisted of subunits showing a "cauliflower" appearance, indicating agglomeration of even smaller particles. The number and size of the crystals increased with time of exposure. 3. These particles represent highly resistant fluoride reservoirs and may be of clinical significance.

  10. [Reference values of calcium, vitamin D, phosphorus, magnesium and fluoride for the Venezuelan population].

    PubMed

    Macías-Tomei, Coromoto; Palacios, Cristina; Mariño Elizondo, Mariana; Carías, Diamela; Noguera, Dalmacia; Chávez Pérez, José Félix

    2013-12-01

    The following micronutrients were considered together for their role in bone health: calcium, vitamin D, phosphorus, magnesium and fluoride. Calcium: not enough is known to change current recommendations. In adolescents and adults, limited data suggest that consuming the recommended level is associated with normal bone mass. In older adults, the limited data reported low consumption and a high rate of fractures but there is no information on whether the current values are adequate. Vitamin D: the limited data reported high deficiency in older adults, which was related to osteoporosis. Given the recent increase in North American recommendation for their contribution to bone health, we proposed to increase the recommendation to 400-600 IU/d for Venezuela. Phosphorus, magnesium and fluoride: the lack of local data does not support changing the latest recommendations. Therefore, it highlights the lack of local studies to assess current recommendations. Studies are needed to estimate the intake of these micronutrients in the population and evaluate their interaction and their relation to bone and overall health. Information of the adequacy of these nutrients in human milk for infants is needed. Alto, it is necessary to implement an effective nutrition surveillance system and implement interventions that maximize bone health from an early stage, including the design and implementation of a dairy policy that leads to an increase in production and consumption by the population. PMID:25924466

  11. EFFECT OF FLUORIDE VARNISHES CONTAINING DIFFERENT CALCIUM PHOSPHATE SOURCES ON MINERALIZATION OF INITIAL PRIMARY ENAMEL LESIONS.

    PubMed

    Rirattanapong, Praphasri; Vongsavan, Kadkao; Saengsirinavin, Chavengkiat; Pornmahala, Tuenjai

    2014-11-01

    This study was conducted to evaluate the effect of fluoride varnishes containing different calcium phosphate sources on demineralization of initial primary enamel lesions. Forty-eight sound primary incisors were completely coated with nail varnish except for two 1 x 1 mm windows before being placed in demineralizing solution for 4 days. After demineralization, one of the windows in each tooth was coated with nail varnish. The teeth were randomly divided into four groups (A to D; n = 12), and then the other (exposed) window was treated with: Group A: deionized water, Group B: Duraphat® fluoride varnish, Group C: Clinpro™ White varnish and Group D: Enamel Pro® varnish. The pH-cycling regimen was carried out consisting of demineralization (6 hours) and remineralization (18 hours) for 7 days. Polarized light microscopy was used to evaluate the lesion depth initially and then after a seven-day pH cycle. Lesion depth was measured using a computerized method with the Image-Pro® Plus Program. The pair t-test was used to compare lesion depths before and after treatment. Differences in mean lesion depths among the groups were compared with the one-way ANOVA and Tukey's multiple comparison tests with 95% confidence intervals. The lesion depths had a significant difference between before and after treatment of the all groups. There was a significant increase in lesion depth in Group A compared to the other groups. No significant differences were seen among Groups B, C and D, containing fluoride and the different calcium phosphate sources in inhibiting progression of initial primary enamel lesions. PMID:26466437

  12. Study on the methylene blue adsorption from wastewaters by pore-expanded calcium fluoride sludge adsorbent.

    PubMed

    Hong, Junming; Lin, Bing; Hong, Gui-Bing; Chang, Chang-Tang

    2014-04-01

    The adsorption of methylene blue (MB) onto pore-expanded calcium fluoride sludge (ECF) by the batch adsorption technique was investigated. The results showed that the adsorption capacity increased with increasing MB concentration but decreased as pH was increased. In order to investigate the adsorption mechanisms, three simplified isotherm models and kinetic models were used in this study. The best-fit adsorption isotherm was achieved with the Temkin model. Furthermore, the pseudo-second-order kinetic model agreed very well with the dynamical behavior for the adsorption of MB onto ECF. Thermodynamic studies revealed that the adsorption process of MB onto ECF was spontaneous and exothermic. The results indicated that ECF adsorbed MB efficiently and could be used as a waste adsorbent for the removal of cationic dyes in wastewater treatment.

  13. The effect of supplementation of calcium, vitamin D, boron, and increased fluoride intake on bone mechanical properties and metabolic hormones in rat.

    PubMed

    Ghanizadeh, G; Babaei, M; Naghii, Mohammad Reza; Mofid, M; Torkaman, G; Hedayati, M

    2014-04-01

    Evidence indicates that optimal nutrition plays a role in bone formation and maintenance. Besides major components of mineralization such as calcium, phosphorus, and vitamin D, other nutrients like boron and fluoride have beneficial role, too. In this study, 34 male Wistar rats were divided into five groups: control diet, fluoride, fluoride + boron, fluoride + calcium + vitamin D, and fluoride + boron + calcium + vitamin D. Boron equal to 1.23 mg, calcium and vitamin D equal to 210 mg + 55 IU and fluoride equal to 0.7 mg/rat/day was added to their drinking water for 8 weeks. Plasma blood samples and bones were collected. Findings are evidence that fluoride + boron intake revealed significant positive effects on bone mechanical properties and bone metabolic hormones. These findings suggest that combined intake of these two elements has beneficial effects on bone stiffness and breaking strength comparing to even calcium + vitamin D supplementation. This evidence dealing with health problems related to bone and skeletal system in humans should justify further investigation of the role of boron and fluoride with other elements in relation to bone.

  14. Divalent fluoride doped cerium fluoride scintillator

    DOEpatents

    Anderson, David F.; Sparrow, Robert W.

    1991-01-01

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

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

    PubMed

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

    2016-03-01

    In Northern Thailand, incidences of fluorosis resulting from the consumption of high-fluoride drinking-water have been documented. In this study, we mapped the high-fluoride endemic areas and described the relevant transport processes of fluoride in enriched waters in the provinces of Chiang Mai and Lamphun. Over one thousand surface and sub-surface water samples including a total of 995 collected from shallow (depth: ≤ 30 m) and deep (> 30 m) wells were analysed from two unconnected high-fluoride endemic areas. At the Chiang Mai site, 31% of the shallow wells contained hazardous levels (≥ 1.5 mg/L) of fluoride, compared with the 18% observed in the deep wells. However, at the Lamphun site, more deep wells (35%) contained water with at least 1.5mg/L fluoride compared with the shallow wells (7%). At the Chiang Mai site, the high-fluoride waters originate from a nearby geothermal field. Fluoride-rich geothermal waters are distributed across the area following natural hydrological pathways of surface and sub-surface water flow. At the Lamphun site, a well-defined, curvilinear high-fluoride anomalous zone, resembling that of the nearby conspicuous Mae Tha Fault, was identified. This similarity provides evidence of the existence of an unmapped, blind fault as well as its likely association to a geogenic source (biotite-granite) of fluoride related to the faulted zone. Excessive abstraction of ground water resources may also have affected the distribution and concentration of fluoride at both sites. The distribution of these high-fluoride waters is influenced by a myriad of complex natural and anthropogenic processes which thus created a challenge for the management of water resources for safe consumption in affected areas. The notion of clean and safe drinking water can be found in deeper aquifers is not necessarily true. Groundwater at any depth should always be tested before the construction of wells. PMID:26747991

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

    PubMed

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

    2016-03-01

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

  17. An AC phase measuring interferometer for measuring dn/dT of fused silica and calcium fluoride at 193 nm

    SciTech Connect

    Shagam, R.N.

    1998-09-01

    A novel method for the measurement of the change in index of refraction vs. temperature (dn/dT) of fused silica and calcium fluoride at the 193 nm wavelength has been developed in support of thermal modeling efforts for the development of 193 nm-based photolithographic exposure tools. The method, based upon grating lateral shear interferometry, uses a transmissive linear grating to divide a 193 nm laser beam into several beam paths by diffraction which propagate through separate identical material samples. One diffracted order passing through one sample overlaps the undiffracted beam from a second sample and forms interference fringes dependent upon the optical path difference between the two samples. Optical phase delay due to an index change from heating one of the samples causes the interference fringes to change sinusoidally with phase. The interferometer also makes use of AC phase measurement techniques through lateral translation of the grating. Results for several samples of fused silica and calcium fluoride are demonstrated.

  18. Application of reutilization technology to calcium fluoride sludge from semiconductor manufacturers.

    PubMed

    Liu, Wei-Ting; Li, Kung-Cheh

    2011-01-01

    Glass ceramics were prepared from mixtures of wastes generated from refining of waste glass and semiconductor industrial wastewater sludge. The aim is then indeed to study the possible use and effects of integrating calcium fluoride (CaF2) as present in semiconductor wastewater sludge in the silica (glass) melts. CaF2 sludge was blended with a conditioner according to characteristics of the target. Calcium oxide-silicon dioxide-aluminum oxide system glass ceramics have relatively high melting points. Addition of CaF2 sludge to fluxes can significantly reduce the melting point and hence improve the kinetics of the reactions. CaF2 sludge and waste glass were co-melted in various ratios to elucidate their interactions at various heating temperatures. The results indicate that the lowest melting temperature was 1163 degrees C, obtained for the CaF2 sludge-waste glass mixture at a ratio 6:4 (wt:wt), which is significantly lower than that of CaF2 sludge (1378 degrees C). The benefits of using melting to dispose of sludge are the reduction of waste and the fixation of heavy metals. Heat treatment was used to convert the obtained glass into glass ceramics. Heavy metal leaching tests revealed that melting conditions lowered the heavy metal concentrations in the leachate to an order of magnitude lower than that in the sludge. Consequently, industrial sludge can be safely used as a fine aggregate material for a potentially wide range of construction applications. PMID:21305892

  19. Calcium Prerinse before Fluoride Rinse Reduces Enamel Demineralization: An in situ Caries Study.

    PubMed

    Souza, João Gabriel S; Tenuta, Livia Maria Andaló; Del Bel Cury, Altair Antoninha; Nóbrega, Diego Figueiredo; Budin, Renan R; de Queiroz, Mateus X; Vogel, Gerald L; Cury, Jaime A

    2016-01-01

    A calcium (Ca) prerinse before a fluoride (F) rinse has been shown to increase oral F levels. We tested the anticaries effect of this combination in a dose-response in situ caries model. In a double-blind, crossover experiment, 10 volunteers carried enamel slabs in palatal appliances for 14 days, during which they rinsed twice/day with one of four rinse combinations: (1) a placebo prerinse (150 mM sodium lactate) followed by a distilled water rinse (negative control); (2) a placebo prerinse followed by a 250 ppm F rinse; (3) a placebo prerinse followed by a 1,000 ppm F rinse, or (4) a Ca prerinse (150 mM Ca, as calcium lactate) followed by a 250 ppm F rinse. Sucrose solution was dripped onto the slabs 8×/day to simulate a high cariogenic challenge. The percent surface hardness loss (%SHL) was significantly lower in the Ca prerinse used with the 250 ppm F rinse group (%SHL = 38.0 ± 21.0) when compared with the F rinse alone (%SHL = 59.5 ± 24.1) and similar to the 1,000 ppm F rinse group (%SHL = 42.0 ± 18.3). Compared with the 250 ppm F rinse, the Ca prerinse increased biofilm fluid F only twice (nonsignificant). However, it greatly increased F in biofilm solids (∼22×). The Ca prerinse had little effect on loosely or firmly bound enamel F. The results showed an increased level of protection against demineralization by the use of a Ca prerinse, which seems to be caused by the enhancement of F concentration in the biofilm. PMID:27355353

  20. Enamel caries formation and lesion progression with a fluoride dentifrice and a calcium-phosphate containing fluoride dentifrice: a polarized light microscopic study.

    PubMed

    Hicks, M J; Flaitz, C M

    2000-01-01

    The effects of a fluoride dentifrice (Colgate Total) and a calcium-phosphate containing fluoride dentifrice (Enamelon) on caries-like enamel lesion formation and progression were evaluated in vitro. One quarter from each tooth (n = 12) was assigned to one of the study groups: 1) control group [artificial saliva only]; 2) Colgate Total; and 3) Enamelon. The dentifrices were applied to the enamel windows (3 minutes, 3 time per day for 14 days). Following treatment, enamel lesions were created with an acidified gel. After lesion initiation, sections were obtained for polarized light microscopy. To evaluate lesion progression, enamel windows with caries-like lesions in each test group were treated again for 14 days, returned to acidified gels for lesion progression, and then sections were obtained for polarized light microscopy. Mean lesion depths (polarized light, water imbibition) were as follows: 1) Lesion Initiation: Control 109 +/- 19 microns, Colgate Total 76 +/- 14 microns, Enamelon 63 +/- 17 microns; 2) First Lesion Progression: Control 164; +/- 24 microns, Colgate Total 124 +/- 22 microns, Enamelon 110 +/- 19 microns; 3) Second Lesion Progression: Control 235 +/- 23 microns; Colgate Total 172 +/- 27 microns, Enamelon 153 +/- 18 microns. Both Colgate Total and Enamelon enhanced the resistance of sound enamel and caries-like enamel lesions to a continuous in vitro cariogenic challenge when compared with matched controls (P < .05, ANOVA, DMR). Enamelon provided a further reduction in lesion depth for all periods when compared with Colgate Total (P > .05, ANOVA, DMR). Addition of bioavailable calcium and phosphate ions to a fluoride dentifrice may improve the ability of enamel to resist caries initiation and subsequent lesion progression.

  1. Enamel caries formation and lesion progression with a fluoride dentifrice and a calcium-phosphate containing fluoride dentifrice: a polarized light microscopic study.

    PubMed

    Hicks, M J; Flaitz, C M

    2000-01-01

    The effects of a fluoride dentifrice (Colgate Total) and a calcium-phosphate containing fluoride dentifrice (Enamelon) on caries-like enamel lesion formation and progression were evaluated in vitro. One quarter from each tooth (n = 12) was assigned to one of the study groups: 1) control group [artificial saliva only]; 2) Colgate Total; and 3) Enamelon. The dentifrices were applied to the enamel windows (3 minutes, 3 time per day for 14 days). Following treatment, enamel lesions were created with an acidified gel. After lesion initiation, sections were obtained for polarized light microscopy. To evaluate lesion progression, enamel windows with caries-like lesions in each test group were treated again for 14 days, returned to acidified gels for lesion progression, and then sections were obtained for polarized light microscopy. Mean lesion depths (polarized light, water imbibition) were as follows: 1) Lesion Initiation: Control 109 +/- 19 microns, Colgate Total 76 +/- 14 microns, Enamelon 63 +/- 17 microns; 2) First Lesion Progression: Control 164; +/- 24 microns, Colgate Total 124 +/- 22 microns, Enamelon 110 +/- 19 microns; 3) Second Lesion Progression: Control 235 +/- 23 microns; Colgate Total 172 +/- 27 microns, Enamelon 153 +/- 18 microns. Both Colgate Total and Enamelon enhanced the resistance of sound enamel and caries-like enamel lesions to a continuous in vitro cariogenic challenge when compared with matched controls (P < .05, ANOVA, DMR). Enamelon provided a further reduction in lesion depth for all periods when compared with Colgate Total (P > .05, ANOVA, DMR). Addition of bioavailable calcium and phosphate ions to a fluoride dentifrice may improve the ability of enamel to resist caries initiation and subsequent lesion progression. PMID:10736654

  2. Calcium fluoride nanoparticles induced suppression of Streptococcus mutans biofilm: an in vitro and in vivo approach.

    PubMed

    Kulshrestha, Shatavari; Khan, Shakir; Hasan, Sadaf; Khan, M Ehtisham; Misba, Lama; Khan, Asad U

    2016-02-01

    Biofilm formation on the tooth surface is the root cause of dental caries and periodontal diseases. Streptococcus mutans is known to produce biofilm which is one of the primary causes of dental caries. Acid production and acid tolerance along with exopolysaccharide (EPS) formation are major virulence factors of S. mutans biofilm. In the current study, calcium fluoride nanoparticles (CaF2-NPs) were evaluated for their effect on the biofilm forming ability of S. mutans in vivo and in vitro. The in vitro studies revealed 89 % and 90 % reduction in biofilm formation and EPS production, respectively. Moreover, acid production and acid tolerance abilities of S. mutans were also reduced considerably in the presence of CaF2-NPs. Confocal laser scanning microscopy and transmission electron microscopy images were in accordance with the other results indicating inhibition of biofilm without affecting bacterial viability. The qRT-PCR gene expression analysis showed significant downregulation of various virulence genes (vicR, gtfC, ftf, spaP, comDE) associated with biofilm formation. Furthermore, CaF2-NPs were found to substantially decrease the caries in treated rat groups as compared to the untreated groups in in vivo studies. Scanning electron micrographs of rat's teeth further validated our results. These findings suggest that the CaF2-NPs may be used as a potential antibiofilm applicant against S. mutans and may be applied as a topical agent to reduce dental caries.

  3. Calcium fluoride nanoparticles induced suppression of Streptococcus mutans biofilm: an in vitro and in vivo approach.

    PubMed

    Kulshrestha, Shatavari; Khan, Shakir; Hasan, Sadaf; Khan, M Ehtisham; Misba, Lama; Khan, Asad U

    2016-02-01

    Biofilm formation on the tooth surface is the root cause of dental caries and periodontal diseases. Streptococcus mutans is known to produce biofilm which is one of the primary causes of dental caries. Acid production and acid tolerance along with exopolysaccharide (EPS) formation are major virulence factors of S. mutans biofilm. In the current study, calcium fluoride nanoparticles (CaF2-NPs) were evaluated for their effect on the biofilm forming ability of S. mutans in vivo and in vitro. The in vitro studies revealed 89 % and 90 % reduction in biofilm formation and EPS production, respectively. Moreover, acid production and acid tolerance abilities of S. mutans were also reduced considerably in the presence of CaF2-NPs. Confocal laser scanning microscopy and transmission electron microscopy images were in accordance with the other results indicating inhibition of biofilm without affecting bacterial viability. The qRT-PCR gene expression analysis showed significant downregulation of various virulence genes (vicR, gtfC, ftf, spaP, comDE) associated with biofilm formation. Furthermore, CaF2-NPs were found to substantially decrease the caries in treated rat groups as compared to the untreated groups in in vivo studies. Scanning electron micrographs of rat's teeth further validated our results. These findings suggest that the CaF2-NPs may be used as a potential antibiofilm applicant against S. mutans and may be applied as a topical agent to reduce dental caries. PMID:26610805

  4. Assessing the Influence of Calcium Fluoride on Pyrite Electrochemical Dissolution and Mine Drainage pH.

    PubMed

    Wang, Luying; Liu, Qingyou; Zheng, Kai; Li, Heping

    2016-07-01

    We investigated the influence of dissolved calcium fluoride, CaF(aq), on the electrochemical dissolution of pyrite and the corresponding environmental effects on acid mine drainage (AMD). The experimental results showed that CaF(aq) promotes pyrite electrochemical dissolution. When the CaF(aq) concentration increased from 0 to 10 mg L up to saturation, the promoting efficiency was 15.80 and 57.25%, respectively. The reason for this phenomenon is that F and Fe form FeF, and at a higher scan potential, F and Fe form the ion complex FeF. The mechanisms include: (i) the decreasing charge transfer resistance at the double layer due to the iron fluorine complex formation; and (ii) the decreasing passivation resistance at the cover layer due to the strong penetration of F ions through it into the double layer. Although the hydrolysis reaction of F in solution could increase the pH value of mine drainage, the AMD was significantly aggravated because CaF(aq) promoted the pyrite electrochemical dissolution. PMID:27380083

  5. Water Atomization of Barium Fluoride: Calcium Fluoride for Enhanced Flow Characteristics of PS304 Feedstock Powder Blend

    NASA Technical Reports Server (NTRS)

    Stanford, Malcolm K.; DellaCorte, Christopher

    2003-01-01

    PS304 is a plasma spray deposited solid lubricant coating with feedstock composed of NiCr, Cr2O3, Ag, and BaF2-CaF2 powders. The effects of rounded BaF2-CaF2 particles on the gravity-fed flow characteristics of PS304 feedstock have been investigated. The BaF2-CaF2 powder was fabricated by water atomization using four sets of process parameters. Each of these powders was then characterized by microscopy and classified by screening to obtain 45 to 106 micron particles and added incrementally from 0 to 10 wt% to the other constituents of the PS304 feedstock, namely nichrome, chromia, and silver powders. The relationship between feedstock flow rate, measured with the Hall flowmeter, and concentration of fluorides was found to be linear in each case. The slopes of the lines were between those of the linear relationships previously reported using angular and spherical fluorides and were closer to the relationship predicted using the rule of mixtures. The results offer a fluoride fabrication technique potentially more cost-effective than gas atomization processes or traditional comminution processes.

  6. Systemic fluoride.

    PubMed

    Sampaio, Fábio Correia; Levy, Steven Marc

    2011-01-01

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

  7. Systemic fluoride.

    PubMed

    Sampaio, Fábio Correia; Levy, Steven Marc

    2011-01-01

    There is substantial evidence that fluoride, through different applications and formulas, works to control caries development. The first observations of fluoride's effects on dental caries were linked to fluoride naturally present in the drinking water, and then from controlled water fluoridation programs. Other systemic methods to deliver fluoride were later suggested, including dietary fluoride supplements such as salt and milk. These systemic methods are now being questioned due to the fact that many studies have indicated that fluoride's action relies mainly on its post-eruptive effect from topical contact with the tooth structure. It is known that even the methods of delivering fluoride known as 'systemic' act mainly through a topical effect when they are in contact with the teeth. The effectiveness of water fluoridation in many geographic areas is lower than in previous eras due to the widespread use of other fluoride modalities. Nevertheless, this evidence should not be interpreted as an indication that systemic methods are no longer relevant ways to deliver fluoride on an individual basis or for collective health programs. Caution must be taken to avoid excess ingestion of fluoride when prescribing dietary fluoride supplements for children in order to minimize the risk of dental fluorosis, particularly if there are other relevant sources of fluoride intake - such as drinking water, salt or milk and/or dentifrice. Safe and effective doses of fluoride can be achieved when combining topical and systemic methods. PMID:21701196

  8. Automated ion-selective electrode method for determining fluoride in natural waters

    USGS Publications Warehouse

    Erdmann, D.E.

    1975-01-01

    An automated fluoride method which uses AutoAnalyzer modules in conjunction with a fluoride ion-selective electrode was evaluated. The results obtained on 38 natural water samples are in excellent agreement with those determined by a similar manual method (average difference = 0.026 mg/l). An average fluoride concentration of 0.496 mg/l was found when several natural water samples were spiked with 0.50 mg/l fluoride. Aluminum is the only significant interfering substance, and it can be easily tolerated if its concentration does not exceed 2 mg/l. Thirty samples were analyzed per hour over a concentration range of 0-2 mg/l.

  9. Reuse of hazardous calcium fluoride sludge from the integrated circuit industry.

    PubMed

    Zhu, Ping; Cao, Zhenbang; Ye, YiLi; Qian, Guangren; Lu, Bo; Zhou, Ming; Zhou, Jin

    2013-11-01

    The Chinese integrated circuit industry has been transformed from a small state-owned sector into a global competitor, but chip manufacturing produces large amounts of calcium fluoride sludges (CFS). In China, landfill is a current option for treating CFS. In order to solve the problem of unavailable landfill sites and prevent fluorine from dissolved CFS polluting water sources, CFS was tested as a component for a ceramic product made with sodium borate, sodium phosphate and waste alumina using a low-temperature sintering technology, and the effects of various factors on characteristics of the ceramic were investigated to optimize the process. The best sintering temperature was controlled at 700°C, and the optimal raw material ratio of the ceramic was 11% sodium borate, 54% sodium phosphate, 30% CFS and 5% waste alumina. The CFS ceramic was characterized by a morphological structure and X-ray diffraction. The results indicated that CFS was transformed into Na2Ca(PO4)F as an inert and a main crystalline phase in the ceramic, which was enclosed by the borophosphate glass. Toxicity characteristic leaching procedure, corrosion resistance and compressive strength tests verified CFS ceramic as a qualified construction ceramic material, and the fluorine from CFS was solidified in the inert crystalline phase, which would not be released to cause secondary pollution. This novel technology not only avoids the CFS hydrolyzing reaction forming harmful hydrofluoric acid gas at 800°C and above, but also produces high-performance ceramics as a construction material, in accordance with the concept of sustainable development. PMID:24025370

  10. Reuse of hazardous calcium fluoride sludge from the integrated circuit industry.

    PubMed

    Zhu, Ping; Cao, Zhenbang; Ye, YiLi; Qian, Guangren; Lu, Bo; Zhou, Ming; Zhou, Jin

    2013-11-01

    The Chinese integrated circuit industry has been transformed from a small state-owned sector into a global competitor, but chip manufacturing produces large amounts of calcium fluoride sludges (CFS). In China, landfill is a current option for treating CFS. In order to solve the problem of unavailable landfill sites and prevent fluorine from dissolved CFS polluting water sources, CFS was tested as a component for a ceramic product made with sodium borate, sodium phosphate and waste alumina using a low-temperature sintering technology, and the effects of various factors on characteristics of the ceramic were investigated to optimize the process. The best sintering temperature was controlled at 700°C, and the optimal raw material ratio of the ceramic was 11% sodium borate, 54% sodium phosphate, 30% CFS and 5% waste alumina. The CFS ceramic was characterized by a morphological structure and X-ray diffraction. The results indicated that CFS was transformed into Na2Ca(PO4)F as an inert and a main crystalline phase in the ceramic, which was enclosed by the borophosphate glass. Toxicity characteristic leaching procedure, corrosion resistance and compressive strength tests verified CFS ceramic as a qualified construction ceramic material, and the fluorine from CFS was solidified in the inert crystalline phase, which would not be released to cause secondary pollution. This novel technology not only avoids the CFS hydrolyzing reaction forming harmful hydrofluoric acid gas at 800°C and above, but also produces high-performance ceramics as a construction material, in accordance with the concept of sustainable development.

  11. Factors affecting fluoride and natural organic matter (NOM) removal from natural waters in Tanzania by nanofiltration/reverse osmosis.

    PubMed

    Shen, Junjie; Schäfer, Andrea I

    2015-09-15

    This study examined the feasibility of nanofiltration (NF) and reverse osmosis (RO) in treating challenging natural tropical waters containing high fluoride and natural organic matter (NOM). A total of 166 water samples were collected from 120 sources within northern Tanzania over a period of 16 months. Chemical analysis showed that 81% of the samples have fluoride levels exceeding the WHO drinking guideline of 1.5mg/L. The highest fluoride levels were detected in waters characterized by high ionic strength, high inorganic carbon and on some occasions high total organic carbon (TOC) concentrations. Bench-scale experiments with 22 representative waters (selected based on fluoride concentration, salinity, origin and in some instances organic matter) and 6 NF/RO membranes revealed that ionic strength and recovery affected fluoride retention and permeate flux. This is predominantly due to osmotic pressure and hence the variation of diffusion/convection contributes to fluoride transport. Different membranes had distinct fluoride removal capacities, showing different raw water concentration treatability limits regarding the WHO guideline compliance. BW30, BW30-LE and NF90 membranes had a feed concentration limit of 30-40 mg/L at 50% recovery. NOM retention was independent of water matrices but is governed predominantly by size exclusion. NOM was observed to have a positive impact on fluoride removal. Several mechanisms could contribute but further studies are required before a conclusion could be drawn. In summary, NF/RO membranes were proved to remove both fluoride and NOM reliably even from the most challenging Tanzanian waters, increasing the available drinking water sources.

  12. Factors affecting fluoride and natural organic matter (NOM) removal from natural waters in Tanzania by nanofiltration/reverse osmosis.

    PubMed

    Shen, Junjie; Schäfer, Andrea I

    2015-09-15

    This study examined the feasibility of nanofiltration (NF) and reverse osmosis (RO) in treating challenging natural tropical waters containing high fluoride and natural organic matter (NOM). A total of 166 water samples were collected from 120 sources within northern Tanzania over a period of 16 months. Chemical analysis showed that 81% of the samples have fluoride levels exceeding the WHO drinking guideline of 1.5mg/L. The highest fluoride levels were detected in waters characterized by high ionic strength, high inorganic carbon and on some occasions high total organic carbon (TOC) concentrations. Bench-scale experiments with 22 representative waters (selected based on fluoride concentration, salinity, origin and in some instances organic matter) and 6 NF/RO membranes revealed that ionic strength and recovery affected fluoride retention and permeate flux. This is predominantly due to osmotic pressure and hence the variation of diffusion/convection contributes to fluoride transport. Different membranes had distinct fluoride removal capacities, showing different raw water concentration treatability limits regarding the WHO guideline compliance. BW30, BW30-LE and NF90 membranes had a feed concentration limit of 30-40 mg/L at 50% recovery. NOM retention was independent of water matrices but is governed predominantly by size exclusion. NOM was observed to have a positive impact on fluoride removal. Several mechanisms could contribute but further studies are required before a conclusion could be drawn. In summary, NF/RO membranes were proved to remove both fluoride and NOM reliably even from the most challenging Tanzanian waters, increasing the available drinking water sources. PMID:26005995

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

    PubMed

    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. PMID:24660269

  14. Access to Fluoridated Water and Adult Dental Caries: A Natural Experiment.

    PubMed

    Peres, M A; Peres, K G; Barbato, P R; Höfelmann, D A

    2016-07-01

    Systematic reviews have found no evidence to support a benefit of water fluoridation (WF) to prevent dental caries in adult populations. The aim of this natural experiment was to investigate whether lifetime access to fluoridated water is associated with dental caries experience among adults from Florianópolis, Brazil. The data originated from a population-based cohort study (EpiFloripa Adult) initiated in 2009 (n = 1,720) when participants were aged 20 to 59 years. The second wave was carried out in 2012 (n = 1,140) and included a dental examination and a face-to-face questionnaire. Participants residing at the same address since the age of 7 y or before were included in the primary analyses. Sensitivity analyses were also performed. WF was implemented in the city in 2 different periods of time: 1982 (60% of the population) and 1996. Dental caries was assessed by the decayed, missing, and filled teeth (DMFT) index. A combination of residential status, participant's age, and year of implementation of WF permitted the creation of participants' lifetime access to fluoridated water: >75%, 50% to 75%, and <50% of a participant's lifetime. Covariates included sex, age, socioeconomic mobility, educational attainment, income, pattern of dental attendance, and smoking. Participants who accessed fluoridate water <50% of their lifetime presented a higher mean rate ratio of DMFT (1.39; 95% CI, 1.05-1.84) compared with those living >75% of their lifetime with residential access to fluoridated water. Participants living between 50% and 75% and <50% of their lives in fluoridated areas presented a decayed and filled teeth mean ratio of 1.34 (95% CI, 1.02-1.75) and 1.47 (95% CI, 1.05-2.04) higher than those with residential access to fluoridated water >75% of their lifetime, respectively. Longer residential lifetime access to fluoridated water was associated with less dental caries even in a context of multiple exposures to fluoride. PMID:27053119

  15. The occurrence and geochemistry of fluoride in some natural waters of Kenya

    NASA Astrophysics Data System (ADS)

    Gaciri, S. J.; Davies, T. C.

    1993-03-01

    In recent years the acquisition of considerable additional data on the hydrogeochemical behaviour of fluoride in natural waters of Kenya has been made possible by extensive surface-water and groundwater sampling campaigns as well as by improvements in analytical techniques. Ultimately, the principal source of fluoride relates to emissions from volcanic activity associated with the East African Rift System. Through various intermediate steps, but also directly, fluoride passes into the natural water system and components of the food chain. Ingestion by man is mainly through drinking water and other beverages. River waters in Kenya generally have a fluoride concentration lower than the recommended level (1.3 ppm) for potable water, thus promoting susceptibility to dental caries. Groundwaters and lake waters show considerably higher fluoride contents, resulting in the widespread incidence of fluorosis in areas where groundwater is the major source of drinking water, and lake fish is a regular component of the diet. This paper presents a synthesis of the data so far obtained on the sources and distribution of fluoride in the hydrological system of Kenya, examines the extent of fluorine toxicity and puts forward recommendations to combat or minimise the problem.

  16. Crystallographic nature of fluoride in enameloids of fish.

    PubMed

    LeGeros, R Z; Suga, S

    1980-01-01

    X-ray diffraction studies on calcified tissues (teeth and/or scales) of fish and of shark showed that the presence of fluoride affects the crystallite size and lattice parameters of the apatite phase. An inverse correlation between F contents (ranging from 0.2 to 3.8 wt% F) and alpha-axis dimensions (9.441 to 9.375 +/- 0.003 A) exists for both synthetic and enameloid apatites and is consistent with the F-for-OH substitution in the apatite, idealized as Ca10(PO4)6(OH)2 and Ca10(PO4)6F2, for fluoride-free and maximum fluoride-substituted apatite, respectively. In synthetic systems, the incorporation of F is found to be dependent on the F concentration of the media from which the apatite formed. This dependency is also observed between F content of the dentine apatites and the F concentration of the water from which the fish can (i.e., less than 0.08 ppmF in fresh water, about 1.3 ppm in seawater). However, no such dependency was observed between the F incorporation in fish enameloid apatite and the F concentration in the water of origin. In some cases, the F incorporated in the enameloid apatite is much in excess of what can be expected from the F concentration of water. These observations suggest that in some fish, a fluoride-concentrating mechanism is operative during the formation of the enameloid but not during the formation of the dentine, and this mechanism appears to be specie-related.

  17. Strontium hydroxyapatite and strontium carbonate as templates for the precipitation of calcium-phosphates in the absence and presence of fluoride

    NASA Astrophysics Data System (ADS)

    Sternitzke, Vanessa; Janousch, Markus; Heeb, Michèle B.; Hering, Janet G.; Johnson, C. Annette

    2014-06-01

    The heterogeneous precipitation of calcium-phosphates on calcium hydroxyapatite (Ca10(PO4)6(OH)2 or HAP) in the presence and absence of fluoride is important in the formation of bone and teeth, protection against tooth decay, dental and skeletal fluorosis and defluoridation of drinking water. Strontium hydroxyapatite (Sr10(PO4)6(OH)2 or SrHAP) and strontium carbonate (SrCO3) were used as calcium-free seed templates in precipitation experiments conducted with varying initial calcium-to-phosphate (Ca/P) or calcium-to-phosphate-to-fluoride (Ca/P/F) ratios. Suspensions of SrHAP or SrCO3 seed templates (which were calcium-limited for both templates and phosphate-limited in the case of SrCO3) were reacted at pH 7.3 (25 °C) over 3 days. The resulting solids were examined with Scanning Transmission Electron Microscopy (STEM), X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), and X-ray Photoelectron Spectroscopy (XPS), X-ray Absorption Near Edge Structure (XANES), and Extended X-ray Absorption Fine Structure spectroscopy (EXAFS). Calcium apatite was the predominant phase identified by all techniques independent of the added Ca/P ratios and of the presence of fluoride. It was not possible to make an unambiguous distinction between HAP and fluorapatite (Ca10(PO4)6F2, FAP). The apatite was calcium-deficient and probably contained some strontium.

  18. Stability of fluoride complex with silica and its distribution in natural water systems

    USGS Publications Warehouse

    Roberson, C.E.; Barnes, R.B.

    1978-01-01

    Fluoride reacts with silicic acid to form SiF2-6. A fluoride electrode was used to obtain an equilibrium constant of 1030.18 for the reaction:Si(OH) 0 6 + 6F-+4H+ = SiF 2- 6 + 4H2O at 25??C. Although there may be some experimental evidence for existence of traces of species containing less than six F- ions per silicon (n = 6), the species SiF2-6 predominates for n values from about 0.1 to 6. Silicic-acid complexing with fluoride is important only in solutions which have rather low pH and low concentrations of other cations which compete with silicon for fluoride. Computations for cold volcanic condensates from Hawaii indicate that for some samples much of the silicon is complexed by fluoride as SiF2-6. However, in most cooled acidic natural water samples Al and Fe are more important than Si in complexing fluoride. ?? 1978.

  19. In vitro evaluation of remineralization efficacy of different calcium- and fluoride-based delivery systems on artificially demineralized enamel surface

    PubMed Central

    Gangrade, Aparajita; Gade, Vandana; Patil, Sanjay; Gade, Jaykumar; Chandhok, Deepika; Thakur, Deepa

    2016-01-01

    Background: Caries is the most common dental disease facing the world population. Caries can be prevented by remineralizing early enamel lesions. Aim: To evaluate remineralization efficacy of stannous fluoride (SnF2), casein phosphopeptide-amorphous calcium phosphate with fluoride (CPP-ACPF) and calcium sucrose phosphate (CaSP). Materials and Methods: Fifty enamel samples were taken; they were divided into five groups (n = 10). Demineralization was carried out with Groups A, B, C, and E. Remineralization was carried out with Groups A, B, and C for 7 days using SnF2, CPP-ACPF, and CaSP, respectively. In Group D, no surface treatment was carried out, to mark as positive control whereas Group E was kept as negative control with only surface demineralization of enamel. Enamel microhardness was tested using Vickers's microhardness tester after 7 day remineralization regime. Statistical Analysis: One-way analysis of variance and post hoc Tukey tests were performed. Results: The mean microhardness values in descending order: Positive control > SnF2> CaSP > CPP-ACPF > negative control. Conclusion: All remineralizing agents showed improved surface remineralization. However, complete remineralization did not occur within 7 days. SnF2 showed the highest potential for remineralization followed by CaSP and CPP-ACPF. PMID:27563180

  20. The influence of lithium fluoride on in vitro biocompatibility and bioactivity of calcium aluminate-pMMA composite cement.

    PubMed

    Oh, S H; Choi, S Y; Choi, S H; Lee, Y K; Kim, K N

    2004-01-01

    The objective of this study is to assess the influence of lithium fluoride on in vitro biocompatibility and bioactivity of calcium aluminate (CA)-polymethylmethacrylate (PMMA) composite cement exhibiting quick setting time ( < 15 min), low exothermic temperature (< 47 degrees C), and high compressive strength (> 100 MPa). The biocompatibility was measured by examining cytotoxicity tests such as the agar diffusion test with L929 cell line and the hemolysis test with fresh rabbit blood. To estimate the bioactivity of CA-PMMA composite cement, we determined hydroxyapatite (HAp) formation on the surface of composite cement in the simulated body (SBF) solution by using thin-film XRD, XPS, SEM, EPMA and ICP-AES. The results of biocompatibility tests indicated that all experimental compositions of this study had no cytotoxicity and no hemolysis so that there was no cytotoxicity with regard to non-reacted monomers (MMA and TEGDMA) and lithium fluoride. The results of bioactivity tests revealed that CA-PMMA composite cement without lithium fluoride did not form HAp on its surface after 60 days of soaking in the SBF. On the other hand, LiAl2(OH)7 . 2H2O and HAp were formed on the surface of CA-PMMA composite cement including 1.0% by weight of lithium fluoride after 7 and 15 days of soaking in the SBF, respectively. The 5 microm of LiAl2(OH)7 . 2H2O and HAp mixed layers were formed on the surface of specimen after 60 days of soaking in the SBF.

  1. Competitive adsorption of fluoride and natural organic matter onto activated alumina.

    PubMed

    Mouelhi, Meral; Giraudet, Sylvain; Amrane, Abdeltif; Hamrouni, Béchir

    2016-09-01

    Natural organic matter (NOM) is a major water constituent that affects the performance of water treatment processes. Several studies have shown that NOM can be adsorbed on the surface of oxides and may compete with other ions. The overall goal of this study was essentially to investigate the competitive adsorption between fluoride and NOM on activated alumina (AA). For this purpose, a humic acid (HA) was used as a model compound for NOM. The interaction of NOM with fluoride, the simultaneous competitive adsorption, and the effect of preloading AA with NOM were investigated. The specific absorbance of HA was determined at 254 nm. Size-exclusion chromatography measurements confirmed the adsorption of aromatic fractions of NOM onto AA. The presence of HA in the system inhibited fluoride sorption onto AA and the removal yield using fresh AA decreased from 70.4 % to 51.0 % in the presence of HA. The decrease was more pronounced using AA preloaded with HA, reaching 37.7 %. The interference of coexisting ions and their effect on fluoride removal capacity were evaluated, showing a severe impact of the presence of phosphate on the removal capacity unlike nitrates and sulfates, which slightly improved the fluoride sorption. PMID:26849225

  2. Comparison of aluminum modified natural materials in the removal of fluoride ions.

    PubMed

    Teutli-Sequeira, A; Solache-Ríos, M; Martínez-Miranda, V; Linares-Hernández, I

    2014-03-15

    The removal behaviors of fluoride ions from aqueous solutions and drinking water by aluminum modified hematite, zeolitic tuff and calcite were determined. Drinking water containing naturally 8.29 mg of fluoride ions per liter was characterized. The hematite, zeolitic tuff and calcite were aluminum modified by an electrochemical method. The effects of contact time and the dose of adsorbent were determined. The PZC (point of zero charge) values for aluminum modified hematite, zeolitic tuff and calcite were 6.2, 5.8 and 8.4, respectively. Adsorption kinetic data were best fitted to pseudo-second-order and Elovich models and equilibrium data to Langmuir-Freundlich isotherm model. The highest fluoride sorption capacities (10.25 and 1.16 mg/g for aqueous solutions and drinking water respectively) were obtained for aluminum modified zeolite with an adsorbent dosage of 10 g/L and an initial F(-) concentration of 9 and 8.29 mg/L for aqueous solutions and drinking water respectively (the final concentrations were 0.08 and 0.7 mg/L respectively). The main mechanism involved in the adsorption of fluoride ions is chemisorption on heterogeneous materials according to the results obtained by fitting the data to kinetic and isotherm models respectively. Aluminum modified zeolitic tuff showed the best characteristics for the removal of fluoride ions from water.

  3. Competitive adsorption of fluoride and natural organic matter onto activated alumina.

    PubMed

    Mouelhi, Meral; Giraudet, Sylvain; Amrane, Abdeltif; Hamrouni, Béchir

    2016-09-01

    Natural organic matter (NOM) is a major water constituent that affects the performance of water treatment processes. Several studies have shown that NOM can be adsorbed on the surface of oxides and may compete with other ions. The overall goal of this study was essentially to investigate the competitive adsorption between fluoride and NOM on activated alumina (AA). For this purpose, a humic acid (HA) was used as a model compound for NOM. The interaction of NOM with fluoride, the simultaneous competitive adsorption, and the effect of preloading AA with NOM were investigated. The specific absorbance of HA was determined at 254 nm. Size-exclusion chromatography measurements confirmed the adsorption of aromatic fractions of NOM onto AA. The presence of HA in the system inhibited fluoride sorption onto AA and the removal yield using fresh AA decreased from 70.4 % to 51.0 % in the presence of HA. The decrease was more pronounced using AA preloaded with HA, reaching 37.7 %. The interference of coexisting ions and their effect on fluoride removal capacity were evaluated, showing a severe impact of the presence of phosphate on the removal capacity unlike nitrates and sulfates, which slightly improved the fluoride sorption.

  4. Comparison of a dual-phase fluoride toothpaste containing calcium, phosphate, and sodium bicarbonate with a regular fluoride toothpaste on calculus formation.

    PubMed

    Putt, Mark S; Milleman, Kimberly R; Milleman, Jeffery L; Ghassemi, Annahita

    2004-09-01

    This clinical study compared the effect on dental calculus formation of a dual-phase fluoride dentifrice containing sodium bicarbonate, calcium, and phosphate with that of a regular dentifrice using a short-term clinical model in which calculus formation was facilitated. A total of 87 adult volunteers completed this study, which was a double-blind, parallel-group design, consisting of 2-week pretrial and trial periods separated by a washout period. A partial-mouth technique was used wherein the lower anterior teeth were protected from brushing by a custom-fitted toothshield, which doubled as an applicator for an undiluted dentifrice, twice daily. Calculus was measured on the labial/lingual surfaces of six lower anterior teeth by the Volpe-Manhold Index (V-MI). Subjects used a non-tartar-control dentifrice during the pretrial period to determine calculus formation rates, and these V-MI scores were used as baseline data for random allocation to either a control or test product for the trial period. Subjects who were accepted into the study, based on existing tartar deposits, readily formed calculus during the pretrial period using the toothshield method. During the trial period, subjects who were assigned the test dentifrice had comparable amounts of calculus accumulation to those who used the control dentifrice. However, subjects in the test dentifrice group had significantly lower (16%) calculus scores on lingual surfaces than those in the control group. Intragroup comparisons of V-MI data from the pretrial period with those from the trial period provided similar overall results to the comparisons between groups. This study demonstrated that a dual-phase baking soda dentifrice containing calcium and phosphate did not increase calculus accumulation relative to a regular dentifrice when used by adults with a propensity for developing calculus. PMID:15645907

  5. Biocompatibility of fluoride-coated magnesium-calcium alloys with optimized degradation kinetics in a subcutaneous mouse model.

    PubMed

    Drynda, Andreas; Seibt, Juliane; Hassel, Thomas; Bach, Friedrich Wilhelm; Peuster, Matthias

    2013-01-01

    The principle of biodegradation has been considered for many years in the development of cardiovascular stents, especially for patients with congenital heart defects. A variety of materials have been examined with regard to their suitability for cardiovascular devices. Iron- and magnesium-based stents were investigated intensively during the last years. It has been shown, that iron, or iron based alloys have slow degradation kinetics whereas magnesium-based systems exhibit rapid degradation rates. Recently we have developed fluoride coated binary magnesium-calcium alloys with reduced degradation kinetics. These alloys exhibit good biocompatibility and no major adverse effects toward smooth muscle and endothelial cells in in vitro experiments. In this study, these alloys were investigated in a subcutaneous mouse model. Fluoride coated (fc) magnesium, as well as MgCa0.4%, MgCa0.6%, MgCa0.8%, MgCa1.0%, and a commercially available WE43 alloy were implanted in form of (fc) cylindrical plates into the subcutaneous tissue of NMRI mice. After a 3 and 6 months follow-up, the (fc) alloy plates were examined by histomorphometric techniques to assess their degradation rate in vivo. Our data indicate that all (fc) alloys showed a significant corrosion. For both time points the (fc) MgCa alloys showed a higher corrosion rate in comparison to the (fc) WE43 reference alloy. Significant adverse effects were not observed. Fluoride coating of magnesium-based alloys can be a suitable way to reduce degradation rates. However, the (fc) MgCa alloys did not exhibit decreased degradation kinetics in comparison to the (fc) WE43 alloy in a subcutaneous mouse model.

  6. Combining casein phosphopeptide-amorphous calcium phosphate with fluoride: synergistic remineralization potential of artificially demineralized enamel or not?

    NASA Astrophysics Data System (ADS)

    Elsayad, Iman; Sakr, Amal; Badr, Yahia

    2009-07-01

    Recaldent is a product of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP). The remineralizing potential of CPP-ACP per se, or when combined with 0.22% Fl gel on artificially demineralized enamel using laser florescence, is investigated. Mesial surfaces of 15 sound human molars are tested using a He-Cd laser beam at 441.5 nm with 18-mW power as an excitation source on a suitable setup based on a Spex 750-M monochromator provided with a photomultiplier tube (PMT) for detection of collected autofluorescence from sound enamel. Mesial surfaces are subjected to demineralization for ten days. The spectra from demineralized enamel are measured. Teeth are divided into three groups according to the remineralizing regimen: group 1 Recaldent per se, group 2 Recaldent combined with fluoride gel and ACP, and group 3 artificial saliva as a positive control. After following these protocols for three weeks, the spectra from the remineralized enamel are measured. The spectra of enamel autofluorescence are recorded and normalized to peak intensity at about 540 nm to compare spectra from sound, demineralized, and remineralized enamel surfaces. A slight red shift occurred in spectra from demineralized enamel, while a blue shift may occur in remineralized enamel. Group 2 shows the highest remineralizing potential. Combining fluoride and ACP with CPP-ACP can give a synergistic effect on enamel remineralization.

  7. Improved laser damage threshold performance of calcium fluoride optical surfaces via Accelerated Neutral Atom Beam (ANAB) processing

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, S.; Walsh, M.; Svrluga, R.; Thomas, M.

    2015-11-01

    Optics are not keeping up with the pace of laser advancements. The laser industry is rapidly increasing its power capabilities and reducing wavelengths which have exposed the optics as a weak link in lifetime failures for these advanced systems. Nanometer sized surface defects (scratches, pits, bumps and residual particles) on the surface of optics are a significant limiting factor to high end performance. Angstrom level smoothing of materials such as calcium fluoride, spinel, magnesium fluoride, zinc sulfide, LBO and others presents a unique challenge for traditional polishing techniques. Exogenesis Corporation, using its new and proprietary Accelerated Neutral Atom Beam (ANAB) technology, is able to remove nano-scale surface damage and particle contamination leaving many material surfaces with roughness typically around one Angstrom. This surface defect mitigation via ANAB processing can be shown to increase performance properties of high intensity optical materials. This paper describes the ANAB technology and summarizes smoothing results for calcium fluoride laser windows. It further correlates laser damage threshold improvements with the smoothing produced by ANAB surface treatment. All ANAB processing was performed at Exogenesis Corporation using an nAccel100TM Accelerated Particle Beam processing tool. All surface measurement data for the paper was produced via AFM analysis on a Park Model XE70 AFM, and all laser damage testing was performed at Spica Technologies, Inc. Exogenesis Corporation's ANAB processing technology is a new and unique surface modification technique that has demonstrated to be highly effective at correcting nano-scale surface defects. ANAB is a non-contact vacuum process comprised of an intense beam of accelerated, electrically neutral gas atoms with average energies of a few tens of electron volts. The ANAB process does not apply mechanical forces associated with traditional polishing techniques. ANAB efficiently removes surface

  8. Fluoride in the environment and its metabolism in humans.

    PubMed

    Jha, Sunil Kumar; Mishra, Vinay Kumar; Sharma, Dinesh Kumar; Damodaran, Thukkaram

    2011-01-01

    The presence of environmental fluoride and its impact on human health is well documented. When consumed in adequate quantity, fluoride prevents dental caries, assists in the formation of dental enamels, and prevents deficiencies in bone mineralization. At excessive exposure levels, ingestion of fluoride causes dental fluorosis skeletal fluorosis, and manifestations such as gastrointestinal, neurological, and urinary problems. The distribution of fluoride in the environment is uneven and largely is believed to derive from geogenic causes. The natural sources of fluoride are fluorite, fluorapatite, and cryolite, whereas anthropogenic sources include coal burning, oil refining, steel production, brick-making industries, and phosphatic fertilizer plants, among others. Among the various sources of fluoride in the environment, those of anthropogenic origin have occasionally been considered to be major ones. The gourndwater is more susceptible to fluoride accumulation and contamination than are other environmental media, primarily because of its contact with geological substrates underneath. The high fluoride concentration in water usually reflects the solubility of fluoride (CaF₂). High concentrations are also often associated with soft, alkaline, and calcium-deficient waters. The fluoride compounds that occur naturally in drinking water are almost totally bioavailable (90%) and are completely absorbed from the gastrointestinal tract. As a result, drinking water is considered to be the potential source of fluoride that causes fluorosis. Because the bioavailability of fluoride is generally reduced in humans when consumed with milk or a calcium-rich diet, it is highly recommended that the inhabitants of fluoride-contaminated areas should incorporate calcium-rich foods in their routine diet. Guidelines for limiting the fluoride intake from drinking water have been postulated by various authorities. Such limits are designed to protect public health and should reflect all

  9. What is next for the Dietary Reference Intakes for bone metabolism related nutrients beyond calcium: phosphorus, magnesium, vitamin D, and fluoride?

    PubMed

    Bergman, Christine; Gray-Scott, Darlene; Chen, Jau-Jiin; Meacham, Susan

    2009-02-01

    The science supporting the Dietary Reference Intakes (DRI) for phosphorus, magnesium, vitamin D, and fluoride was examined in this review. Along with the previous article on calcium in this series both of these reviews represent all the DRI for nutrients considered essential for bone metabolism and health, as reported in the Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride (Institute of Medicine, Food and Nutrition Board (FNB), 1997). The Recomended Dietary Allowances (RDA) or adequate intake (AI), and the tolerable upper intake level (UL) were recommended for each of these essential nutrients. For adults and in the case of fluoride, for infants as well, UL were calculated since all of these nutrients have the potential for mild to detrimental side effects. Dietary intake data and controversies regarding the role these nutrients may play in other chronic diseases have also been discussed. Advances and controversies reported since the publication of the DRI for these nutrients were also addressed in this review. A recent Dietary Reference Intake Research Synthesis Workshop report identified an extensive range of suggested future research directions needed to improve our understanding of these bone-related nutrients and their contributions to human health.

  10. What is next for the Dietary Reference Intakes for bone metabolism related nutrients beyond calcium: phosphorus, magnesium, vitamin D, and fluoride?

    PubMed

    Bergman, Christine; Gray-Scott, Darlene; Chen, Jau-Jiin; Meacham, Susan

    2009-02-01

    The science supporting the Dietary Reference Intakes (DRI) for phosphorus, magnesium, vitamin D, and fluoride was examined in this review. Along with the previous article on calcium in this series both of these reviews represent all the DRI for nutrients considered essential for bone metabolism and health, as reported in the Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride (Institute of Medicine, Food and Nutrition Board (FNB), 1997). The Recomended Dietary Allowances (RDA) or adequate intake (AI), and the tolerable upper intake level (UL) were recommended for each of these essential nutrients. For adults and in the case of fluoride, for infants as well, UL were calculated since all of these nutrients have the potential for mild to detrimental side effects. Dietary intake data and controversies regarding the role these nutrients may play in other chronic diseases have also been discussed. Advances and controversies reported since the publication of the DRI for these nutrients were also addressed in this review. A recent Dietary Reference Intake Research Synthesis Workshop report identified an extensive range of suggested future research directions needed to improve our understanding of these bone-related nutrients and their contributions to human health. PMID:18989832

  11. Fluoride coatings make effective lubricants in molten sodium environment

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Coating bearing surfaces with calcium fluoride-barium fluoride film provides effective lubrication against sliding friction in molten sodium and other severe environments at high and low temperatures.

  12. Ab-initio Calculations of Electronic Properties of Calcium Fluoride (CaF2)

    NASA Astrophysics Data System (ADS)

    Bohara, Bir; Franklin, Lashounda; Malozovsky, Yuriy; Bagayoko, Diola

    We have performed first principle, local density approximation (LDA) calculations of electronic and related properties of cubic calcium fluorite (CaF2) . Our non-relativistic computations employed the Ceperley and Alder LDA potential and the linear combination of atomic orbitals (LCAO) formalism. The implementation of the LCAO formalism followed the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). We discuss the electronic energy bands, including the large band gap, total and partial density of states, electron and hole effective masses, and the bulk modulus. Our calculated, indirect (X- Γ) band gap is 12.98 eV; it is 1 eV above an experimental value of 11.8 eV. The calculated bulk modulus (82.89 GPA) is excellent agreement with the experimental result of 82.0 +/-0.7. Our predicted equilibrium lattice constant is 5.42Å. Acknowledgments: This work is funded in part by the National Science Foundation (NSF) and the Louisiana Board of Regents, through LASiGMA [Award Nos. EPS- 1003897, NSF (2010-15)-RII-SUBR], and NSF HRD-1002541, the US Department of Energy, National, Nuclear Security Administration (NNSA) (Award No. DE-NA-0002630), LaSPACE, and LONI-SUBR.

  13. Lubricating Properties of Ceramic-Bonded Calcium Fluoride Coatings on Nickel-Base Alloys from 75 to 1900 deg F

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.

    1962-01-01

    The endurance life and the friction coefficient of ceramic-bonded calcium fluoride (CaF2) coatings on nickel-base alloys were determined at temperatures from 75 F to 1900 F. The specimen configuration consisted of a hemispherical rider (3/16-in. rad.) sliding against the flat surface of a rotating disk. Increasing the ambient temperature (up to 1500 F) or the sliding velocity generally reduced the friction coefficient and improved coating life. Base-metal selection was critical above 1500 F. For instance, cast Inconel sliding against coated Inconel X was lubricated effectively to 1500 F, but at 1600 F severe blistering of the coatings occurred. However, good lubrication and adherence were obtained for Rene 41 sliding against coated Rene 41 at temperatures up to 1900 F; no blisters developed, coating wear life was fairly good, and the rider wear rate was significantly lower than for the unlubricated metals. Friction coefficients were 0.12 at 1500 F, 0.15 at 1700 F, and 0.17 at 1800 F and 1900 F. Because of its ready availability, Inconel X appears to be the preferred substrate alloy for applications in which the temperature does not exceed 1500 F. Rene 41 would have to be used in applications involving higher temperatures. Improved coating life was derived by either preoxidizing the substrate metals prior to the coating application or by applying a very thin (less than 0.0002 in.) burnished and sintered overlay to the surface of the coating. Preoxidation did not affect the friction coefficient. The overlay generally resulted in a higher friction coefficient than that obtained without the overlay. The combination of both modifications resulted in longer coating life and in friction coefficients intermediate between those obtained with either modification alone.

  14. EFFECT OF CARBAMIDE PEROXIDE-BASED BLEACHING AGENTS CONTAINING FLUORIDE OR CALCIUM ON TENSILE STRENGTH OF HUMAN ENAMEL

    PubMed Central

    Giannini, Marcelo; Silva, Alessandra Peres; Cavalli, Vanessa; Leme, Adriana Franco Paes

    2006-01-01

    Objective: The aim of this study was to evaluate the effects of carbamide peroxide-based bleaching agents (CPG) containing fluoride (CF) or calcium (CCa) on the ultimate tensile strength of enamel (UTS). Method: A "cube-like" resin composite structure was built-up on the occlusal surface of twenty-two sound third molars to facilitate specimen preparation for the micro-tensile test. The restored teeth were serially sectioned in buccal-lingual direction in slices with approximate 0.7 mm thickness. Each slice was trimmed with a fine diamond bur to reduce the buccal, internal slope enamel of the cusps to a dumb-bell shape with a cross-sectional area at the "neck" of less than 0.5 mm2. The samples were randomly divided into 12 groups (n=11). The control groups were not submitted to the bleaching regimen. Specimens were treated with 10% CPG gel or with 10% CPG formulations containing CF (0.2% and 0.5%) or CCa (0.05% and 0.2%). Bleached groups received the application of the 10% CPGs for 6 hours/day at 37° C, during 14 consecutive days and were stored in artificial saliva (AS) or 100% relative humidity (RH) among each application. After bleaching, specimens were tested with the microtensile method at 0.5 mm/min. Data were analyzed by two-way ANOVA and Tukey test (5%). Results: No significant difference was observed between groups stored in AS or RH. Specimens treated with CF or CCa presented similar UTS as unbleached control groups. Conclusion: Either 10% CPG formulations containing CF or CCa can preserve the UTS after bleaching regimen. PMID:19089036

  15. Effect of fluoride and low versus high levels of dietary calcium on mRNA expression of osteoprotegerin and osteoprotegerin ligand in the bone of rats.

    PubMed

    Yu, Jun; Gao, Yanhui; Sun, Dianjun

    2013-06-01

    The ratio of osteoprotegerin ligand (OPGL) to osteoprotegerin (OPG) determines the delicate balance between bone resorption and synthesis. The main objective of the present study is to investigate the possible role of OPGL and OPG in the bone metabolism of rats exposed to fluoride and the protective or aggravating effect of calcium (Ca). In a 6-month study, 270 weanling male Sprague-Dawley rats weighing between 70 and 90 g were divided randomly into six groups of 45 rats in each group. Three groups (groups I, III, and V)served as controls and drank deionized water and were fed purified rodent diets containing either 1,000 mg Ca/kg (low Ca), 5,000 mg Ca/kg (normal Ca), or 20,000 mg Ca/kg (high Ca). The three experimental groups (groups II, IV, and VI) were given the same diets but they drank water containing 100 mg F ion/L (from NaF). Every 2 months 15 rats were randomly selected from each group and sacrificed for the study. The ratio of OPGL mRNA to OPG mRNA was significantly increased by the sixth month in the distal femur joints of the F-exposed rats. Serum tartrate-resistant acid phosphatase activity and serum calcitonin activity in the F-exposed groups was increased, although changes were not apparent in the serum alkaline phosphatase or Gla-containing proteins, especially in the low calcium and high calcium diet F-exposed groups. The results indicated that OPG and OPGL may play important roles in skeletal fluorosis, and that fluoride may enhance osteoclast formation and induce osteoclastic bone destruction. A high Ca diet did not play a protective role, but rather may aggravate the damage of fluoride.

  16. Purex Processing of Dissolved Sand, Slag, and Crucible Containing High Levels of Boric Acid and Calcium Fluoride

    SciTech Connect

    Kyser, E.A.

    1998-05-01

    The plutonium solution obtained from the dissolution of SSC in F- Canyon will be high in fluoride. Flowsheet adjustments must be made to increase the plutonium extraction in the solvent extraction cycle to keep Pu losses from being excessive.

  17. Effect of fluoride on calcium ion concentration and expression of nuclear transcription factor kappa-B ρ65 in rat hippocampus.

    PubMed

    Zhang, Jing; Zhu, Wen-Jing; Xu, Xiao-Hong; Zhang, Zi-Gui

    2011-07-01

    The study investigated the neurotoxicity of drinking water fluorosis in rat hippocampus. Just weaning male Sprague-Dawley (SD) rats were given 15, 30, 60 mg/L NaF solution and tap water for 9 months. The calcium ion concentration ([Ca(2+)]) in synaptosomes was measured by double wavelength fluorescence spectrophotometer and the expression level of nuclear transcription factor kappa-B ρ65 (NF-κB ρ65) in hippocampal CA3 region was measured by immunohistochemistry. The results showed that [Ca(2+)] significantly increased (F = 33.218, P < 0.01) in moderate fluoride group compared with the control group, and the expression level of NF-κB ρ65 in CA3 region presented an increasing trend as fluoride concentration increased. These results indicate that increase of synaptosomes [Ca(2+)] and NF-κB ρ65 expression level may be the molecular basis of central nervous system damage caused by chronic fluoride intoxication. NF-κB ρ65 in CA3 region is probably a target molecule for fluorosis.

  18. The effect of casein phosphopeptide-amorphous calcium phosphate paste and sodium fluoride mouthwash on the prevention of dentine erosion: An in vitro study

    PubMed Central

    Moezizadeh, Maryam; Alimi, Azar

    2014-01-01

    Aim: The purpose was to compare the effect of 0.2% sodium fluoride mouthwash and casein phosphopeptide-amorphous calcium phosphate paste on prevention of dentin erosion. Materials and Methods: Buccal surfaces of 36 sound premolar teeth were ground flat and polished with abrasive discs. Half the polished surfaces were covered with tape to maintain a reference surface. Samples were randomly allocated into three groups. Group A was pretreated with tooth mousse (TM) 4 times a day for 5 days. Group B was pretreated with 0.2% sodium fluoride mouthwash 4 times a day for 5 days. Group C was considered as the control group with no pretreatment. In the next step, the samples were exposed to Coca-Cola 4 times a day for 3 days. After each erosive cycle, the samples were rinsed with deionized water and stored in artificial saliva. The surface loss was determined using profilometry. Results: The erosion in both Groups A and B was less than the control group. The surface loss in mouthwash group was significantly lower than in the control group. Erosion in TM group was more than the mouthwash group and less than the control group. Conclusion: Sodium fluoride mouthwash is more effective for prevention of dentin erosion. PMID:24944448

  19. Fluoridation Basics

    MedlinePlus

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

  20. Biomarkers of fluoride in children exposed to different sources of systemic fluoride.

    PubMed

    Buzalaf, M A R; Rodrigues, M H C; Pessan, J P; Leite, A L; Arana, A; Villena, R S; Forte, F D S; Sampaio, F C

    2011-02-01

    There has been no comparison between fluoride concentrations in urine and nails of children exposed to different sources of systemic fluoride. The aim of this study was to compare the relationship between fluoride intake with urinary fluoride excretion and fluoride concentrations in fingernails and toenails of children receiving fluoride from artificially fluoridated water (0.6-0.8 mg F/L, n = 25), naturally fluoridated water (0.6-0.9 mg F/L, n = 21), fluoridated salt (180-200 mg F/Kg, n = 26), and fluoridated milk (0.25 mg F, n = 25). A control population was included (no systemic fluoride, n = 24). Fluoride intake from diet and dentifrice, urinary fluoride excretion, and fluoride concentrations in fingernails/toenails were evaluated. Fluoride was analyzed with an ion-selective electrode. Urinary fluoride excretion in the control community was significantly lower when compared with that in the fluoridated cities, except for the naturally fluoridated community. However, the same pattern was not as evident for nails. Both urinary fluoride output and fluoride concentrations in fingernails/toenails were significantly correlated to total fluoride intake. However, the correlation coefficients for fluoride intake and urinary fluoride output were lower (r = 0.28, p < 0.01) than those observed for fingernails/toenails (r = 0.36, p < 0.001), suggesting that nails might be slightly better indicators of fluoride intake at the individual level.

  1. Nature of the Enhancement in Ferroelectric Properties by Gold Nanoparticles in Vinylidene Fluoride and Trifluoroethylene Copolymer.

    PubMed

    Tsutsumi, Naoto; Kosugi, Ryusei; Kinashi, Kenji; Sakai, Wataru

    2016-07-01

    Ferroelectric polymers are a candidate for versatile and cheap data storage memory devices, with easy processing for a large-scale device. Easy switching and large remanent polarization of preferentially formed β-crystal dipoles in a copolymer of vinylidene fluoride and trifluoroethylene (P(VDF-TrFE)) are promising properties for versatile memory devices. At higher frequency switching, however, the remanent polarization is reduced and a high coercive field, an electric field for polarization switching is required. The addition of a small amount of nanoparticles (NPs) significantly improves these ferroelectric properties in fluoropolymers. Here, we show that the addition of NPs of gold (Au), silver (Ag), and silicon oxide (SiO2) enhanced the ferroelectric properties in P(VDF-TrFE). AuNPs significantly affected a 40% increase of the remanent polarization, 14% reduction of the coercive field, and 100% increase of the switching speed of ferroelectric polarization. The nature of these enhancements due to the addition of NPs is verified. A higher shift of the binding energy of Au (4f7/2 and 4f5/2) and an increase of the fluorine ion (F(-)) was observed in AuNP-doped P(VDF-TrFE). Strong interactions between the AuNPs and the ferroelectric backbone gave rise to the formation of the interfacial polarization, which induced the local electric field to enhance the ferroelectric properties of the increment of the remanent polarization, the reduction of the coercive field, and faster switching speed.

  2. Evaluation and comparison of the efficacy of low fluoridated and calcium phosphate-based dentifrice formulations when used with powered and manual toothbrush in children with autism

    PubMed Central

    Awasthi, Prateek; Peshwani, Bharti; Tiwari, Shilpi; Thakur, Ruchi; Shashikiran, N. D.; Singla, Shilpy

    2015-01-01

    Background: Autism is a neurobiological disorder characterized by impaired social interaction, communication difficulties, and lacking manual dexterity. These limitations make the oral hygiene maintenance very difficult. Aim: The aim of this present study is to evaluate and compare the efficacy of low fluoridated and calcium phosphate-based dentifrice formulations when used with powered and manual toothbrush in children with autism. Setting and Design: Sample comprised 22 children with autism who daily visited a day care and education center named ARUSHI - a center for children with special health care needs in Bhopal. Methods: Children were divided into two groups (Group A and B) according to toothbrush used and further divided into subgroups (A1 and B1 [low fluoridated − Pediflor toothpaste] and A2 and B2 [calcium sucrose phosphate − Enafix toothpaste]). Oral hygiene instructions and brushing technique demonstration were given every day for a period of 1-month. Oral health status was evaluated before and after the study using simplified oral hygiene index (OHI-S) and its Miglani's modification for primary dentition, plaque index (PI), gingival index (GI), and decayed, missing, and filled teeth (DMFT)/deft index. The perception of parents regarding oral hygiene practices for their kids was also evaluated by an awareness and attitude questionnaire. Statistical Analysis: OHI-S, GI, PI, and DMFT/deft were statistically evaluated using Mann–Whitney U- test. Results and Conclusion: Mean value of OHI-S decreased significantly with powered toothbrush (0.035 [P < 0.05]) in both groups. However, PI decreased significantly for Enafix when used with powered toothbrush (0.042 [P < 0.05]). Perception of parents was seen to improve significantly after 1-month study (0.000 [P < 0.05]). PMID:26604573

  3. A health risk assessment for fluoride in Central Europe.

    PubMed

    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.

  4. Mechanism of action of a desensitizing fluoride toothpaste delivering calcium and phosphate ingredients in the treatment of dental hypersensitivity. Part III: Prevention of dye penetration through dentin vs a calcium- and phosphate-free control.

    PubMed

    Winston, Anthony E; Charig, Andrew J; Thong, Stephen

    2010-01-01

    It is generally accepted that the pain of dental hypersensitivity resulting from gum recession is from the movement of fluid within the exposed tubules of dentin, causing changes in pressure on the nerve within the pulpal cavity. One method of treating hypersensitivity is to occlude the tubules, preventing fluid movement. This article discusses the use of a dye penetration technique, which establishes this mechanism of action for a desensitizing fluoride toothpaste containing calcium and phosphate. Two groups of intact teeth were perfectly sealed with enamel paint. Windows 100-micro to 200-micro deep were opened on opposite sides of each tooth at the dentin-enamel junction and briefly etched using 20% polyacrylic acid. One batch of teeth was treated eight times for 30 mins each with a 1:3 slurry of the desensitizing toothpaste and another set with a similar slurry prepared from a calcium- and phosphate-free control. A 0.85% aqueous solution of acid red fuchsin dye was applied to each window and allowed to dry. After a brief rinse, the teeth were sectioned across the windows. Almost no dye penetration was seen in teeth treated with the desensitizing toothpaste; however, extensive penetration through the dentin was visible in the control-treated teeth. The differences in dye penetration for the two sets of teeth were significant by both subjective (P < .001) and objective (P < .01) measures. Tubule occlusion because of calcium and phosphate ions from the desensitizing toothpaste accounts for its tooth desensitizing efficacy.

  5. Fluoride in UK rivers.

    PubMed

    Neal, Colin; Neal, Margaret; Davies, Helen; Smith, Jennifer

    2003-10-01

    concentrations within the more contaminated rivers, and this is indicated by a negative upper bound between fluoride and calcium. The waters are undersaturated with respect to fluorite and oversaturated with respect to calcium fluoro-phosphates. This upper bound may reflect either physical controls, such as the availability and size of point and diffuse sources for fluoride coupled to mixing of these sources with rain and soil runoff of low concentration, or solubility controls for a pure or mixed-phase mineral that cannot be specified here.

  6. Fluoride in UK rivers.

    PubMed

    Neal, Colin; Neal, Margaret; Davies, Helen; Smith, Jennifer

    2003-10-01

    concentrations within the more contaminated rivers, and this is indicated by a negative upper bound between fluoride and calcium. The waters are undersaturated with respect to fluorite and oversaturated with respect to calcium fluoro-phosphates. This upper bound may reflect either physical controls, such as the availability and size of point and diffuse sources for fluoride coupled to mixing of these sources with rain and soil runoff of low concentration, or solubility controls for a pure or mixed-phase mineral that cannot be specified here. PMID:14499534

  7. Natural variations in calcium isotope composition as a monitor of bone mineral balance in humans.

    NASA Astrophysics Data System (ADS)

    Skulan, J.; Anbar, A.; Thomas, B.; Smith, S.

    2004-12-01

    The skeleton is the largest reservoir of calcium in the human body and is responsible for the short term control of blood levels of this element. Accurate measurement of changes in bone calcium balance is critical to understanding how calcium metabolism responds to physiological and environmental changes and, more specifically, to diagnosing and evaluating the effectiveness of treatments for osteoporosis and other serious calcium-related disorders. It is very difficult to measure bone calcium balance using current techniques, however, because these techniques rely either on separate estimates of bone resorption and formation that are not quantitatively comparable, or on complex and expensive studies of calcium kinetics using administered isotopic tracers. This difficulty is even more apparent and more severe for measurements of short-term changes in bone calcium balance that do not produce detectable changes in bone mineral density. Calcium isotopes may provide a novel means of addressing this problem. The foundation of this isotope application is the ca. 1.3 per mil fractionation of calcium during bone formation, favoring light calcium in the bone. This fractionation results in a steady-state isotopic offset between calcium in bone and calcium in soft tissues, blood and urine. Perturbations to this steady state due to changes in the net formation or resorption of bone should be reflected in changes in the isotopic composition of soft tissues and fluids. Here we present evidence that easily detectable shifts in the natural calcium isotope composition of human urine rapidly reflect changes in bone calcium balance. Urine from subjects in a 17-week bed rest study was analyzed for calcium isotopic composition. Bed rest promotes net resorption of bone, shifting calcium from bone to soft tissues, blood and urine. The calcium isotope composition of patients in this study shifted toward lighter values during bed rest, consistent with net resorption of isotopically

  8. Anomalous fluoride concentration in groundwater - is it natural or pollution? A stable isotope approach.

    PubMed

    Marimon, Maria Paula Casagrande; Knöller, Kay; Roisenberg, Ari

    2007-06-01

    Fluoride anomalies (up to 11 mg/l) have been detected in groundwater of the central region of Rio Grande do Sul State, Southern Brazil, in an area where fluorosis is endemic. Two hypotheses are investigated concerning the fluoride origin: lithochemical affiliation from regional rock or contamination by fertilisers application. These hypotheses are discussed based on the stable isotope data of water, nitrate, and sulphate, which indicates that the local precipitation is the main groundwater recharge source. The isotopic composition of groundwater sulphate is similar to that of fertiliser sulphate. However, a conclusive assignment of groundwater sulphate to fertiliser origin is not indicated because further possible sulphate sources fall into the same isotopic range. In contrast, the isotopic composition of dissolved nitrate suggests that there is no direct relationship to the use of NPK fertilisers. Hence, an origin of the high fluoride content in groundwater related to long-term rock-water interactions seems likely.

  9. Topical laser application enhances enamel fluoride uptake and tribological properties.

    PubMed

    Jeng, Y-R; Lin, T-T; Huang, J-S; Peng, S-R; Shieh, D-B

    2013-07-01

    Topical fluoride treatment prevents dental caries. However, the resulting calcium-fluoride-like deposits are soft and have poor wear resistance; therefore, frequent treatment is required. Lasers quickly heat surfaces and can be made portable and suitable for oral remedies. We examined the morphology, nanohardness, elastic modulus, nanowear, and fluoride uptake of fluoride-treated enamel followed by CO2 laser irradiation for 5 and 10 sec, respectively. We found that laser treatments significantly increased the mechanical properties of the calcium-fluoride-like deposits. The wear resistance of the calcium-fluoride-like deposits improved about 34% after laser irradiation for 5 sec and about 40% following irradiation for 10 sec. We also found that laser treatments increased fluoride uptake by at least 23%. Overall, laser treatment significantly improved fluoride incorporation into dental tissue and the wear resistance of the protective calcium-fluoride layer.

  10. Calcium

    MedlinePlus

    ... milligrams) of calcium each day. Get it from: Dairy products. Low-fat milk, yogurt, cheese, and cottage ... lactase that helps digest the sugar (lactose) in dairy products, and may have gas, bloating, cramps, or ...

  11. Calcium

    MedlinePlus

    ... supplements and fortified foods include gluconate, lactate, and phosphate. Calcium absorption is best when a person consumes ... also interfere with the body's ability to absorb iron and zinc, but this effect is not well ...

  12. Optimal Fluoridation

    PubMed Central

    Lee, John R.

    1975-01-01

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

  13. Calcium.

    PubMed

    Williams, Robert J P

    2002-01-01

    This chapter describes the chemical and biological value of the calcium ion. In calcium chemistry, our main interest is in equilibria within static, nonflowing systems. Hence, we examined the way calcium formed precipitates and complex ions in solution. We observed thereafter its uses by humankind in a vast number of materials such as minerals, e.g., marble, concrete, mortars, which parallel the biological use in shells and bones. In complex formation, we noted that many combinations were of anion interaction with calcium for example in the uses of detergents and medicines. The rates of exchange of calcium from bound states were noted but they had little application. Calcium ions do not act as catalysts of organic reactions. In biological systems, interest is in the above chemistry, but extends to the fact that Ca2+ ions can carry information by flowing in one solution or from one solution to another through membranes. Hence, we became interested in the details of rates of calcium exchange. The fast exchange of this divalent ion from most organic binding sites has allowed it to develop as the dominant second messenger. Now the flow can be examined in vitro as calcium binds particular isolated proteins, which it activates as seen in physical mechanical changes or chemical changes and this piece-by-piece study of cells is common. Here, however, we have chosen to stress the whole circuit of Ca2+ action indicating that the cell is organized both at a basal and an activated state kinetic level by the steady state flow of the ion (see Fig. 11). Different time constants of exchange utilizing very similar binding constants lead to: 1) fast responses as in the muscle of an animal; or 2) slower change as in differentiation of an egg or seed. Many other changes of state may relate to Ca2+ steady-state levels of flow in the circuitry and here we point to two: 1) dormancy in reptiles and animals; and 2) sporulation in both bacteria and lower plants. In the other chapters of

  14. Mechanism of action of a desensitizing fluoride toothpaste delivering calcium and phosphate ingredients in the treatment of dental hypersensitivity. Part II: comparison with a professional treatment for tooth hypersensitivity.

    PubMed

    Charig, Andrew J; Thong, Stephen; Flores, Florita; Gupta, Shivank; Major, Elizabeth; Winston, Anthony E

    2009-01-01

    Tooth hypersensitivity can occur when gum recession causes exposure of dentin. Tiny tubules, which permeate dentin, provide open passageways from the mouth to the intradental nerve in the pulpal cavity. Under such circumstances, stimuli in the mouth can cause pressure on the intradental nerve, leading to pain. Sealing the outside of the tubules with an impermeable substance can effectively treat hypersensitivity. One such clinically proven composition is a professionally applied tooth desensitizer, which has been shown to initially produce a layer of amorphous calcium phosphate (ACP) on the surface of dentin. Under the influence of fluoride, ACP reforms as hydroxyapatite (HAP), which has essentially the same composition as tooth mineral. Three fluoride toothpastes that deliver calcium and phosphate salts to the teeth also have been demonstrated in clinical trials to relieve hypersensitivity. This study compared the mechanism of action of these toothpastes to that of the professional desensitizer. A single application of the professional desensitizer or multiple applications of any of the three toothpastes was shown to reduce dentin permeability. A conventional fluoride toothpaste also was found to inhibit fluid flow through the dentin but to a lesser degree than the other toothpastes. The desensitizer and the three toothpastes were found to occlude the dentinal tubules with a layer of calcium phosphate that had a calcium-to-phosphate ratio consistent with the formation of ACP or HAP. The morphology of the coherent mineral layer formed by Arm & Hammer Enamel Care Sensitive was similar, especially to that produced by the desensitizer. In contrast, the conventional toothpaste left localized areas of surface residue composed of silica particles. The mechanism of action of the three toothpastes that deliver calcium and phosphate salts is the same as that of the professional desensitizer.

  15. Mechanism of action of a desensitizing fluoride toothpaste delivering calcium and phosphate ingredients in the treatment of dental hypersensitivity. Part II: comparison with a professional treatment for tooth hypersensitivity.

    PubMed

    Charig, Andrew J; Thong, Stephen; Flores, Florita; Gupta, Shivank; Major, Elizabeth; Winston, Anthony E

    2009-01-01

    Tooth hypersensitivity can occur when gum recession causes exposure of dentin. Tiny tubules, which permeate dentin, provide open passageways from the mouth to the intradental nerve in the pulpal cavity. Under such circumstances, stimuli in the mouth can cause pressure on the intradental nerve, leading to pain. Sealing the outside of the tubules with an impermeable substance can effectively treat hypersensitivity. One such clinically proven composition is a professionally applied tooth desensitizer, which has been shown to initially produce a layer of amorphous calcium phosphate (ACP) on the surface of dentin. Under the influence of fluoride, ACP reforms as hydroxyapatite (HAP), which has essentially the same composition as tooth mineral. Three fluoride toothpastes that deliver calcium and phosphate salts to the teeth also have been demonstrated in clinical trials to relieve hypersensitivity. This study compared the mechanism of action of these toothpastes to that of the professional desensitizer. A single application of the professional desensitizer or multiple applications of any of the three toothpastes was shown to reduce dentin permeability. A conventional fluoride toothpaste also was found to inhibit fluid flow through the dentin but to a lesser degree than the other toothpastes. The desensitizer and the three toothpastes were found to occlude the dentinal tubules with a layer of calcium phosphate that had a calcium-to-phosphate ratio consistent with the formation of ACP or HAP. The morphology of the coherent mineral layer formed by Arm & Hammer Enamel Care Sensitive was similar, especially to that produced by the desensitizer. In contrast, the conventional toothpaste left localized areas of surface residue composed of silica particles. The mechanism of action of the three toothpastes that deliver calcium and phosphate salts is the same as that of the professional desensitizer. PMID:19998729

  16. Fluoride and Oral Health.

    PubMed

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

    2016-06-01

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

  17. Fluoride and Oral Health.

    PubMed

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

    2016-06-01

    The discovery during the first half of the 20th century of the link between natural fluoride, adjusted fluoride levels in drinking water and reduced dental caries prevalence proved to be a stimulus for worldwide on-going research into the role of fluoride in improving oral health. Epidemiological studies of fluoridation programmes have confirmed their safety and their effectiveness in controlling dental caries. Major advances in our knowledge of how fluoride impacts the caries process have led to the development, assessment of effectiveness and promotion of other fluoride vehicles including salt, milk, tablets, toothpaste, gels and varnishes. In 1993, the World Health Organization convened an Expert Committee to provide authoritative information on the role of fluorides in the promotion of oral health throughout the world (WHO TRS 846, 1994). This present publication is a revision of the original 1994 document, again using the expertise of researchers from the extensive fields of knowledge required to successfully implement complex interventions such as the use of fluorides to improve dental and oral health. Financial support for research into the development of these new fluoride strategies has come from many sources including government health departments as well as international and national grant agencies. In addition, the unique role which industry has played in the development, formulation, assessment of effectiveness and promotion of the various fluoride vehicles and strategies is noteworthy. This updated version of 'Fluoride and Oral Health' has adopted an evidence-based approach to its commentary on the different fluoride vehicles and strategies and also to its recommendations. In this regard, full account is taken of the many recent systematic reviews published in peer reviewed literature. PMID:27352462

  18. Fluoride in the UK diet.

    PubMed

    Ruxton, Carrie

    2014-08-12

    Fluoride is a naturally occurring mineral that can be obtained from foods and fluids originating from soils containing fluoride, as well as by drinking water that has been fluoridated. While consuming adequate fluoride intake can deliver benefits for dental and bone health, there have been concerns that excessive fluoride intake could lead to dental fluorosis, or even cause harm to bones. This article considers the balance of evidence in this area, and discusses the benefits and potential risks of fluoride in the UK diet. The role of tea as a major contributor to normal fluoride intake is highlighted, alongside some positive implications of this. Information is also provided to help nurses and midwives communicate the latest advice and guidance on fluoride to their patients. PMID:25095960

  19. Fluoride in the UK diet.

    PubMed

    Ruxton, Carrie

    2014-08-12

    Fluoride is a naturally occurring mineral that can be obtained from foods and fluids originating from soils containing fluoride, as well as by drinking water that has been fluoridated. While consuming adequate fluoride intake can deliver benefits for dental and bone health, there have been concerns that excessive fluoride intake could lead to dental fluorosis, or even cause harm to bones. This article considers the balance of evidence in this area, and discusses the benefits and potential risks of fluoride in the UK diet. The role of tea as a major contributor to normal fluoride intake is highlighted, alongside some positive implications of this. Information is also provided to help nurses and midwives communicate the latest advice and guidance on fluoride to their patients.

  20. On the nature of structural disorder in calcium silicate hydrates with a calcium/silicon ratio similar to tobermorite

    SciTech Connect

    Grangeon, Sylvain; Claret, Francis; Lerouge, Catherine; Warmont, Fabienne; Sato, Tsutomu; Anraku, Sohtaro; Linard, Yannick

    2013-10-15

    Four calcium silicate hydrates (C-S-H) with structural calcium/silicon (Ca/Si) ratios ranging from 0.82 ± 0.02 to 0.87 ± 0.02 were synthesized at room temperature, 50, 80, and 110 °C. Their structure was elucidated by collating information from electron probe micro-analysis, transmission electron microscopy, extended X-ray absorption fine structure spectroscopy, and powder X-ray diffraction (XRD). A modeling approach specific to defective minerals was used because sample turbostratism prevented analysis using usual XRD refinement techniques (e.g. Rietveld analysis). It is shown that C-S-H with Ca/Si ratio of ∼ 0.8 are structurally similar to nano-crystalline turbostratic tobermorite, a naturally occurring mineral. Their structure thus consists of sheets of calcium atoms in 7-fold coordination, covered by ribbons of silicon tetrahedra with a dreierketten (wollastonite-like) organization. In these silicate ribbons, 0.42 Si per bridging tetrahedron are missing. Random stacking faults occur systematically between successive layers (turbostratic stacking). Layer-to-layer distance is equal to 11.34 Å. Crystallites have a mean size of 10 nm in the a–b plane, and a mean number of 2.6–2.9 layers stacked coherently along the c* axis.

  1. Quantitative determination of fluoride as a major pollutant in the emissions from the thermal treatment of clayey raw materials.

    PubMed

    Zannini, Paolo

    2002-01-01

    Three clayey raw materials for production of traditional ceramics, all with medium to high fluorine content, have been investigated for determining their attitude to fluoride emission during firing, at varying parameters of the firing cycle, maximum firing temperature included, and in the presence or in the absence of calcium carbonate either added to the sample or naturally present in it. Different analytical methods for the determination of fluoride have been tested, together with different sample preparation procedures aimed to obtain minimum loss of fluoride in the pre-treatment step.

  2. Characterization of calcium isotopes in natural and synthetic barite

    USGS Publications Warehouse

    Griffith, E.M.; Schauble, E.A.; Bullen, T.D.; Paytan, A.

    2008-01-01

    The mineral barite (BaSO4) accommodates calcium in its crystal lattice, providing an archive of Ca-isotopes in the highly stable sulfate mineral. Holocene marine (pelagic) barite samples from the major ocean basins are isotopically indistinguishable from each other (??44/40Ca = -2.01 ?? 0.15???) but are different from hydrothermal and cold seep barite samples (??44/40Ca = -4.13 to -2.72???). Laboratory precipitated (synthetic) barite samples are more depleted in the heavy Ca-isotopes than pelagic marine barite and span a range of Ca-isotope compositions, ??44/40Ca = -3.42 to -2.40???. Temperature, saturation state, a Ba2 + / a SO42 -, and aCa2+/aBa2+ each influence the fractionation of Ca-isotopes in synthetic barite; however, the fractionation in marine barite samples is not strongly related to any measured environmental parameter. First-principles lattice dynamical modeling predicts that at equilibrium Ca-substituted barite will have much lower 44Ca/40Ca than calcite, by -9??? at 0 ??C and -8??? at 25 ??C. Based on this model, none of the measured barite samples appear to be in isotopic equilibrium with their parent solutions, although as predicted they do record lower ??44/40Ca values than seawater and calcite. Kinetic fractionation processes therefore most likely control the extent of isotopic fractionation exhibited in barite. Potential fractionation mechanisms include factors influencing Ca2+ substitution for Ba2+ in barite (e.g. ionic strength and trace element concentration of the solution, competing complexation reactions, precipitation or growth rate, temperature, pressure, and saturation state) as well as nucleation and crystal growth rates. These factors should be considered when investigating controls on isotopic fractionation of Ca2+ and other elements in inorganic and biogenic minerals. ?? 2008 Elsevier Ltd.

  3. INCREASES IN CYTOSOLIC CALCIUM ION LEVELS IN HUMAN NATURAL KILLER CELLS IN RESPONSE TO BUTYLTIN EXPOSURE

    PubMed Central

    Lane, Rhonda; Ghazi, Sabah O.; Whalen, Margaret M.

    2009-01-01

    This study investigated whether exposures to butyltins (BTs), tributylin (TBT) and dibutyltin (DBT) were able to alter cytosolic calcium levels in human natural killer (NK) cells. Additionally, the effects of cytosolic calcium ion increases on the activation state of mitogen activated protein kinases (MAPKs) in NK cells were also investigated. NK cells are an intital immune defense against the development of tumors or viral infections. TBT and DBT are widespread environmental contaminants, due to their various industrial applications. Both TBT and DBT have been shown to decrease the ability of NK cells to lyse tumor cells (lytic function). TBT has also been shown to activate MAPKs in NK cells. The results of this study indicated that TBT increased cytosolic calcium levels by as much as 100% after a 60 min exposure to 500 nM TBT while DBT increased cytosolic calcium levels to a much smaller extent (and required higher concentrations). The results also indicated that increases in cytosolic calcium could activate MAPKs but only for a short period of time (5 min), while previous studies showed that activation of MAPKs by TBT last for at least 6 hours. Thus, it appears that TBT stimulated increases in cytosolic calcium may contribute to, but are not fully responsible for, TBT-induced activation of MAPKs. PMID:19365649

  4. Fluoride metabolism when added to salt.

    PubMed

    Whitford, Gary M

    2005-01-01

    The purpose of this review is to present the general characteristics of the metabolism of fluoride particularly as it occurs when ingested with fluoridated salt. Following the absorption of salt-borne fluoride from the stomach and intestines, its metabolism is identical to that of water-borne fluoride or other vehicles containing ionized fluoride. Because fluoridated salt is almost always ingested with food, however, absorption from the gastrointestinal tract may be delayed or reduced. Reports dealing with this subject have shown that fluoride absorption is delayed and, therefore, peak plasma concentrations are lower than when fluoride is ingested with water. The amount of ingested fluoride that is finally absorbed, however, is not appreciably affected unless the meal is composed mainly of components with high calcium concentrations. In this case, the extent of absorption can be reduced by as much as 50%. Fluoridated salt is also ingested less frequently than fluoridated water. Data are presented to show that the dose size and frequency of ingestion have only minor effects on fluoride retention in the body and on the concentrations in plasma, bone and enamel. Finally, calculations are presented to show that the risk of acute toxicity from fluoridated salt is virtually non-existent.

  5. Fluoride laser crystals: old and new

    NASA Astrophysics Data System (ADS)

    Jenssen, Hans P.; Cassanho, Arlete

    2006-02-01

    The development of oxide and fluoride materials as gain materials of choice for solid state lasers ranges from early materials such as Calcium Fluoride and Calcium Tungstate crystals to the now ubiquitous Nd hosts YLF, YAG and Vanadate. Among Tunable laser materials, MgF II - an early favorite, gave way to superior oxides such as Alexandrite and Ti:Sapphire only to be followed by development of still newer tunable fluoride media, notably, fluoride colquiriites such as Cr-doped LiSAF and LiCaF. Newer fluoride crystals, such as Barium Yttrium Fluoride BaY II F 8 (BYF), KY 3F 10 (KYF) and the tunable Cr doped LiCaGaF 6 are attractive laser materials, but their growth has not been optimized. Key advantages of two of these new crystals are discussed. Crystal growth results for BYF and Cr:LiCaGaF 6 as well as some material characterization are presented.

  6. Influence of the nature of calcium salts on serum calcium, phosphorus, calcitonin, growth hormone, and somatomedin C.

    PubMed

    Reginster, J Y; Denis, D; Albert, A; Gaspar, S; Heynen, G; Deroisy, R; Franchimont, P

    1988-01-01

    Twenty healthy males were randomly divided into three groups. Each subject received either 405 mg elemental calcium (Ca) as a salt linked to an amino acid precursor, 405 mg CaC12 or 1000 mg Ca as Ca gluconolactate and carbonate. In all three cases, Ca intake led to an increase of serum Ca and TCT production and a decrease of PTH liberation. However, when Ca is linked to the amino acid precursor, an elective stimulation of growth hormone (GH) and somatomedin C (SmC) occurs. Due to the nature of its amino acid precursor, this salt seems to stimulate GH and SmC liberation through hypophysis. This could be a major pathway in decoupling of the sequence resorption-formation and therapy of metabolic bone diseases. PMID:3375576

  7. Natural fluoride and trace metal levels of ground and surface waters in the greater Accra region of Ghana.

    PubMed

    Botchway, C A; Ansa-Asare, O D; Antwi, L A

    1996-01-01

    In a study of levels of fluoride and trace metals in ten different stations of both surface and groundwaters in the Greater Accra Region, Ghana, groundwaters were found to have lower pH than surface water, resulting in groundwaters having higher concentrations of dissolved ions. Groundwaters had higher fluoride levels than surface waters. The correlation coefficient for fluoride on total alkalinity and for fluoride on sodium were 0.56 and 0.27 respectively which implied that rock weathering played a minor role in the recorded fluoride enrichment of the underground waters. A likely mechanism for the higher underground fluoride levels could be bacterial decay of plant materials resulting in the release of fluoride to the underground waters. The levels of Cu, Cd, Pb and Zn fell within the expected background ranges. 90% of the sites had Mn levels above the detection limits in both underground and surface waters. 70% of boreholes in Accra plains had Fe levels higher than the WHO recommended limits of 0.3 mg/l for drinking water. Generally, underground waters had higher concentration of fluoride and trace metals than surface waters.

  8. Natural calcium isotonic composition of urine as a marker of bone mineral balance

    USGS Publications Warehouse

    Skulan, J.; Bullen, T.; Anbar, A.D.; Puzas, J.E.; Shackelford, L.; LeBlanc, A.; Smith, S.M.

    2007-01-01

    Background: We investigated whether changes in the natural isotopic composition of calcium in human urine track changes in net bone mineral balance, as predicted by a model of calcium isotopic behavior in vertebrates. If so, isotopic analysis of natural urine or blood calcium could be used to monitor short-term changes in bone mineral balance that cannot be detected with other techniques. Methods: Calcium isotopic compositions are expressed as ??44Ca, or the difference in parts per thousand between the 44Ca/40Ca of a sample and the 44Ca/ 40Ca of a standard reference material. ??44Ca was measured in urine samples from 10 persons who participated in a study of the effectiveness of countermeasures to bone loss in spaceflight, in which 17 weeks of bed rest was used to induce bone loss. Study participants were assigned to 1 of 3 treatment groups: controls received no treatment, one treatment group received alendronate, and another group performed resistive exercise. Measurements were made on urine samples collected before, at 2 or 3 points during, and after bed rest. Results: Urine ??44Ca values during bed rest were lower in controls than in individuals treated with alendronate (P <0.05, ANOVA) or exercise (P <0.05), and lower than the control group baseline (P <0.05, Mest). Results were consistent with the model and with biochemical and bone mineral density data. Conclusion: Results confirm the predicted relationship between bone mineral balance and calcium isotopes, suggesting that calcium isotopic analysis of urine might be refined into a clinical and research tool. ?? 2007 American Association for Clinical Chemistry.

  9. Crystal structure of complex natural aluminum magnesium calcium iron oxide

    NASA Astrophysics Data System (ADS)

    Rastsvetaeva, R. K.; Aksenov, S. M.; Verin, I. A.

    2010-07-01

    The structure of a new natural oxide found near the Tashelga River (Eastern Siberia) was studied by X-ray diffraction. The pseudo-orthorhombic unit cell parameters are a = 5.6973(1) Å, b = 17.1823(4) Å, c = 23.5718(5) Å, β = 90°, sp. gr. Pc. The structure was refined to R = 0.0516 based on 4773 reflections with | F| > 7σ( F) taking into account the twin plane perpendicular to the z axis (the twin components are 0.47 and 0.53). The crystal-chemical formula ( Z = 4) is Ca2Mg{2/IV}Fe{2/(2+)IV}[Al{14/VI}O31(OH)][Al{2/IV}O][AlIV]ALIV(OH)], where the Roman numerals designate the coordination of the atoms. The structure of the mineral is based on wide ribbons of edge-sharing Al octahedra (an integral part of the spinel layer). The ribbons run along the shortest x axis and are inclined to the y and z axes. The adjacent ribbons are shifted with respect to each other along the y axis, resulting in the formation of step-like layers in which the two-ribbon thickness alternates with the three-ribbon thickness. Additional Al octahedra and Mg and Fe2+ tetrahedra are located between the ribbons. The layers are linked together to form a three-dimensional framework by Al tetrahedra, Ca polyhedra, and hydrogen bonds with the participation of OH groups.

  10. Crystal structure of complex natural aluminum magnesium calcium iron oxide

    SciTech Connect

    Rastsvetaeva, R. K. Aksenov, S. M.; Verin, I. A.

    2010-07-15

    The structure of a new natural oxide found near the Tashelga River (Eastern Siberia) was studied by X-ray diffraction. The pseudo-orthorhombic unit cell parameters are a = 5.6973(1) A, b = 17.1823(4) A, c = 23.5718(5) A, {beta} = 90{sup o}, sp. gr. Pc. The structure was refined to R = 0.0516 based on 4773 reflections with vertical bar F vertical bar > 7{sigma}(F) taking into account the twin plane perpendicular to the z axis (the twin components are 0.47 and 0.53). The crystal-chemical formula (Z = 4) is Ca{sub 2}Mg{sub 2}{sup IV}Fe{sub 2}{sup (2+)IV}[Al{sub 14}{sup VI}O{sub 31}(OH)][Al{sub 2}{sup IV}O][Al{sup IV}]AL{sup IV}(OH)], where the Roman numerals designate the coordination of the atoms. The structure of the mineral is based on wide ribbons of edge-sharing Al octahedra (an integral part of the spinel layer). The ribbons run along the shortest x axis and are inclined to the y and z axes. The adjacent ribbons are shifted with respect to each other along the y axis, resulting in the formation of step-like layers in which the two-ribbon thickness alternates with the three-ribbon thickness. Additional Al octahedra and Mg and Fe{sup 2+} tetrahedra are located between the ribbons. The layers are linked together to form a three-dimensional framework by Al tetrahedra, Ca polyhedra, and hydrogen bonds with the participation of OH groups.

  11. Analysis of Naturally Occurring Fluoride in Commercial Teas and Estimation of Its Daily Intake through Tea Consumption.

    PubMed

    Peng, Chuan-yi; Cai, Hui-mei; Zhu, Xiao-hui; Li, Da-xiang; Yang, Yun-qiu; Hou, Ru-yan; Wan, Xiao-chun

    2016-01-01

    The aim of this study was to determine the levels of fluoride in commercial teas and to estimate the contribution of tea consumption to the fluoride recommended daily allowance. A total of 558 tea products in 6 categories, green tea, black tea, oolong tea, pu'er tea, white tea, and reprocessed tea, were collected in the period from 2010 to 2013. The levels of fluoride in infusions of these teas were determined by a fluoride-ion selective electrode. The mean fluoride level in all of the tea samples was 85.16 mg/kg. For each category of tea, the mean fluoride levels were 63.04, 99.74, 52.19, 101.67, 159.78, and 110.54 mg/kg for green tea, black tea, white tea, pu'er tea, oolong tea, and reprocessed tea, respectively. The fluoride content of tea from 4 tea zones in descending order were Southern tea zone (111.39 mg/kg) > Southwest tea zone (78.78 mg/kg) > Jiangnan tea zone (71.73 mg/kg) > Jiangbei tea zone (64.63 mg/kg). These areas produced teas with lower fluoride levels than available foreign-produced tea (161.11 mg/kg). The mean chronic daily intake (CDI) was 0.02 mg/(kg•day) or 1.27 mg/kg. Generally, consuming tea from these 6 categories does not result in the intake of excessive amounts of fluoride for the general population.

  12. Bottled Water and Fluoride

    MedlinePlus

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

  13. Heat storage material comprising calcium chloride-hexahydrate and a nucleating agent

    SciTech Connect

    Gawron, K.; Schroder, J.

    1980-02-19

    The utility of calcium chloride-hexahydrate as a heat storage material is improved when barium carbonate, strontium carbonate, barium fluoride, barium fluoride-hydrofluoride and/or strontium fluoride is used as a nucleating agent to prevent supercooling.

  14. Fluoride Plus Functionalized β-TCP

    PubMed Central

    Karlinsey, R.L.; Pfarrer, A.M.

    2012-01-01

    With more than 50 years of clinical success, fluoride serves as the gold standard agent for preventing tooth decay. In particular, the action of fluoride facilitates saliva-driven remineralization of demineralized enamel and alters solubility beneficially. Still, tooth decay remains problematic, and one way to address it may be through the development of new mineralizing agents. Laboratory and clinical studies have demonstrated that the combination of fluoride and functionalized β-tricalcium phosphate (fTCP) produces stronger, more acid-resistant mineral relative to fluoride, native β-TCP, or fTCP alone. In contrast to other calcium-based approaches that seem to rely on high levels of calcium and phosphate to drive remineralization, fTCP is a low-dose system designed to fit within existing topical fluoride preparations. The functionalization of β-TCP with organic and/or inorganic molecules provides a barrier that prevents premature fluoride-calcium interactions and aids in mineralization when applied via common preparations and procedures. While additional clinical studies are warranted, supplementing with fTCP to enhance fluoride-based nucleation activity, with subsequent remineralization driven by dietary and salivary calcium and phosphate, appears to be a promising approach. PMID:22899679

  15. In vitro calcium availability in bakery products fortified with tuna bone powder as a natural calcium source.

    PubMed

    Nemati, Mahnaz; Kamilah, Hanisah; Huda, Nurul; Ariffin, Fazilah

    2015-08-01

    Avoidance of dairy products due to lactose intolerance can lead to insufficiency of calcium (Ca) in the body. In an approach to address this problem, tuna bone powder (TBP) was formulated as a calcium supplement to fortify bakery products. In a study, TBP recovered by alkaline treatment contained 38.16 g/100 g of calcium and 23.31 g/100 g of phosphorus. The ratio of Ca:P that was close to 2:1 was hence comparable to that in human bones. The availability of calcium in TBP was 53.93%, which was significantly higher than most calcium salts, tricalcium phosphate (TCP) being the exception. In vitro availability of calcium in TBP-fortified cookies or TCP-fortified cookies were comparable at 38.9% and 39.5%, respectively. These values were higher than the readings from TBP-fortified bread (36.7%) or TCP-fortified bread (37.4%). Sensory evaluation of bakery products containing TBP or TCP elicited comparable scores for the two additives from test panels. Hence, TBP could be used in the production of high calcium bakery products that would enjoy consumer acceptance. PMID:27144766

  16. Fluoride in groundwater: toxicological exposure and remedies.

    PubMed

    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 (<0.5 mg/L) is beneficial in promoting 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.

  17. Indirect determination of trace amounts of fluoride in natural waters by ion chromatography: a comparison of on-line post-column fluorimetry and ICP-MS detectors.

    PubMed

    Bayón, M M; Rodríguez Garcia, A; García Alonso, J I; Sanz-Medel, A

    1999-01-01

    An alternative method for the determination of trace levels of fluoride in drinking and sea-water samples is presented. It is based on the formation of the aluminium monofluoride complex in excess of Al3+ and separation of the two species formed (AlF2+ and Al3+) in a small (5 cm long, CG2) ion exchange guard column. The final determination is accomplished by both ICP-MS specific detection and post column derivatisation with fluorimetric detection. Fundamental studies on the formation kinetics of the complex, ion chromatographic separation and optimum aluminium concentration were carried out using spectrofluorimetric detection by post-column reaction of the species with 8-hydroxyquinoline-5-sulfonic acid in a micellar medium of cetyltrimethylammonium bromide. Fluorimetric detection showed good detection limits, but interferences from cations such as Mg2+ and Zn2+ required the use of the longer CS2 ion exchange column. Iron interfered in relatively large amounts but adding EDTA to the sample solution eliminated the interference. A similar separation methodology was applied using ICP-MS detection for the indirect determination of fluoride, by monitoring aluminium at mass 27. In this case, a detection limit of 0.1 ng ml-1 was obtained using 0.45 M HNO3 as eluent and no interference caused by high concentrations of iron was observed. The proposed method was applied to the determination of very low levels of fluoride in natural waters.

  18. Differences in loosely bound fluoride formation and anticaries effect of resin-based fluoride varnishes.

    PubMed

    Maas, Jorge R S; Junior, Italo M Faraco; Lodi, Carolina S; Delbem, Alberto C B

    2013-05-01

    OBJECTIVE.  Our in vitro study evaluated calcium fluoride formation in enamel and the anticaries effect of seven resin-based varnishes under cariogenic challenge. METHODS.  Enamel blocks were subjected to pH cycling. The experimental groups received fluoride varnish application, the positive control received topical fluoride gel treatment, and the negative control did not receive any treatment. The pH cycling surface hardness (SH1 ) and integrated loss of subsurface hardness (ΔKHN) were then determined. We measured the amount of fluoride released into the demineralizing and remineralizing (DE-RE) solutions used in pH cycling. The fluoride concentration in the enamel was determined 24 h after application of the products as loosely bound fluoride and firmly bound fluoride. RESULTS.  Higher deposits of loosely bound fluoride were observed for Duofluorid, followed by Biophat. For Duraphat, Bifluorid, Duraflur, and Duofluorid, no difference was observed in the SH1 and ΔKHN values, with the lowest mineral loss compared to the other groups. The Bifluorid and Duofluorid groups released high fluoride amounts into the DE-RE, and statistically significant difference was noted between them. CONCLUSIONS.  The anticaries effect showed no correlation with higher deposited fluoride amounts, resin type, or fluoride source.

  19. Biomimetic Synthesis of Calcium-Deficient Hydroxyapatite in a Natural Hydrogel

    SciTech Connect

    Hutchens, Stacy A; Benson, Roberto S.; Evans, Barbara R; O'Neill, Hugh Michael; Rawn, Claudia J

    2006-01-01

    A novel composite material consisting of calcium-deficient hydroxyapatite (CdHAP) biomimetically deposited in a bacterial cellulose hydrogel was synthesized and characterized. Cellulose produced by Gluconacetobacter hansenii was purified and sequentially incubated in solutions of calcium chloride followed by sodium phosphate dibasic. A substantial amount of apatite (50-90% of total dry weight) was homogeneously incorporated throughout the hydrogel after this treatment. X-ray diffractometry (XRD) showed that CdHAP crystallites had formed in the cellulose. XRD further demonstrated that the CdHAP was comprised of 10-50nm anisotropic crystallites elongated in the c-axis, similar to natural bone apatite. Fourier transform infrared (FTIR) spectroscopy demonstrated that hydroxyl IR bands of the cellulose shifted to lower wave numbers indicating that a coordinate bond had possibly formed between the CdHAP and the cellulose hydroxyl groups. FTIR also suggested that the CdHAP had formed from an octacalcium phosphate precursor similar to physiological bone. Scanning electron microscopy (SEM) images confirmed that uniform ?1 mm spherical CdHAP particles comprised of nanosized crystallites with a lamellar morphology had formed in the cellulose. The synthesis of the composite mimics the natural biomineralization of bone indicating that bacterial cellulose can be used as a template for biomimetic apatite formation. This composite may have potential use as an orthopedic biomaterial.

  20. REDUCTION OF FLUORIDE TO METAL

    DOEpatents

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

    1960-08-30

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

  1. Parameters influencing ciprofloxacin, ofloxacin, amoxicillin and sulfamethoxazole retention by natural and converted calcium phosphates.

    PubMed

    Bouyarmane, H; El Hanbali, I; El Karbane, M; Rami, A; Saoiabi, A; Saoiabi, S; Masse, S; Coradin, T; Laghzizil, A

    2015-06-30

    The retention of four antibiotics, ciprofloxacin, ofloxacin, amoxicillin and sulfamethoxazole by a natural phosphate rock (francolite) was studied and compared with a converted hydroxyapatite powder. The maximum sorption capacities were found to correlate with the molecular weight of the molecules. The mechanisms of sorption depended mostly on the charge of the antibiotic whereas the kinetics of the process was sensitive to their hydrophobic/hydrophilic character. The two materials showed slightly distinct affinities for the various antibiotics but exhibited similar maximum sorption capacities despite different specific surface areas. This was mainly attributed to the more pronounced hydrophobic character of the francolite phase constituting the natural phosphate. These data enlighten that the retention properties of these mineral phases depend on a complex interplay between the inter-molecular and molecule-solid interactions. These findings are relevant to understand better the contribution of calcium phosphates in the fate and retention of antibiotics in soils.

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

    NASA Astrophysics Data System (ADS)

    Weldesenbet, S. F.; Wohnlich, S.

    2012-12-01

    The Central Main Ethiopian Rift basin is a continental rift system characterized by volcano-tectonic depression endowed with huge geothermal resource and associated natural geochemical changes on groundwater quality. Chemical composition of groundwater in the study area showed a well defined trend along flow from the highland and escarpment to the rift floor aquifer. The low TDS (< 500mg/l) Ca-Mg-HCO3 dominated water at recharge area in the highlands and escarpments evolve progressively into Ca-Na-HCO3 and Na-Ca-HCO3 type waters along the rift ward groundwater flow paths. These waters finally appear as moderate TDS (mean 960mg/l) Na-HCO3 type and as high TDS (> 1000 mg/l) Na-HCO3-Cl type in volcano-lacustrine aquifers of the rift floor. High concentrations of fluoride (up to 97.2 mg/l) and arsenic (up to 98μg/l) are recognized feature of groundwaters which occur mostly in the vicinity of the geothermal fields and the rift lakes in the basin. Fluoride and arsenic content of dry volcaniclastic sediments close to these areas are in the range 666-2586mg/kg and 10-13mg/kg respectively. The relationship between fluoride and calcium concentrations in groundwaters showed negative correlation. Near-equilibrium state attained between the mineral fluorite (CaF2) and the majority of fluoride-rich (>30mg/l) thermal groundwater and shallow cold groundwater. This indicated that the equilibrium condition control the high concentration of fluoride in the groundwaters. Whereas undersaturation state of fluorite in some relatively low-fluoride (<30mg/l) thermal waters indicated a dilution by cold waters. Laboratory batch leaching experiments showed that fast dissolution of fluoride from the sediment samples suddenly leached into the interacting water at the first one hour and then remain stable throughout the experiment. The concentrations of leached fluoride from the hot spring deposits, the lacustrine sediments, and the pyroclastic rock are usually low (1% of the total or less than

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

    SciTech Connect

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

    1995-02-01

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

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

    PubMed Central

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

    2014-01-01

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

  5. Effects of natural organic matter on calcium and phosphorus co-precipitation.

    PubMed

    Sindelar, Hugo R; Brown, Mark T; Boyer, Treavor H

    2015-11-01

    Phosphorus (P), calcium (Ca) and natural organic matter (NOM) naturally occur in all aquatic ecosystems. However, excessive P loads can cause eutrophic or hyper-eutrophic conditions in these waters. As a result, P regulation is important for these impaired aquatic systems, and Ca-P co-precipitation is a vital mechanism of natural P removal in many alkaline systems, such as the Florida Everglades. The interaction of P, Ca, and NOM is also an important factor in lime softening and corrosion control, both critical processes of drinking water treatment. Determining the role of NOM in Ca-P co-precipitation is important for identifying mechanisms that may limit P removal in both natural and engineered systems. The main goal of this research is to assess the role of NOM in inhibiting Ca and P co-precipitation by: (1) measuring how Ca, NOM, and P concentrations affect NOM's potential inhibition of co-precipitation; (2) determining the effect of pH; and (3) evaluating the precipitated solids. Results showed that Ca-P co-precipitation occurs at pH 9.5 in the presence of high natural organic matter (NOM) (≈30 mg L(-1)). The supersaturation of calcite overcomes the inhibitory effect of NOM seen at lower pH values. Higher initial P concentrations lead to both higher P precipitation rates and densities of P on the calcite surface. The maximum surface density of co-precipitated P on the precipitated calcite surface increases with increasing NOM levels, suggesting that NOM does prevent the co-precipitation of Ca and P.

  6. Carbide/fluoride/silver self-lubricating composite

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E. (Inventor)

    1988-01-01

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

  7. Carbide-fluoride-silver self-lubricating composite

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E. (Inventor)

    1987-01-01

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

  8. The effects of fluoridated water on bone strength.

    PubMed

    Turner, C H; Akhter, M P; Heaney, R P

    1992-07-01

    Fluoride from fluoridated water accumulates not only in the enamel of teeth but also in the skeleton. The effects of fluoridated water on the skeleton are not well understood, yet there is some evidence that fluoridated water consumption increases the incidence of fractures. In the present study, femoral bending strength was measured in rats on fluoride intakes that ranged from low levels to levels well above natural high fluoride drinking water. Bone strength followed a biphasic relationship with bone fluoride content. Fluoride had a positive effect on bone strength for lower fluoride intakes and a negative influence on bone strength for higher fluoride intakes. The vertebral fluoride content at which femoral strength was maximum was between 1,100 and 1,500 ppm. The increase in femoral strength at this fluoride level was not accompanied by an increase in femoral bone density. The optimal fluoride content is within the range of bone fluoride contents found in persons living in regions with fluoridated water (1 ppm) for greater than 10 years.

  9. Study on fluoride emission from soils at high temperature related to brick-making process.

    PubMed

    Xie, Z M; Wu, W H; Xu, J M

    2003-02-01

    Characteristics of fluoride emission from 12 soils at temperatures of 400-1,100 degrees C related to the brick-making process were studied. The results obtained in this study indicate that fluoride emission as gaseous HF and SiF4 was related to the firing temperature, soil total fluoride content, soil composition and calcium compounds added to soils. Soils began to release fluoride at temperatures between 500 and 700 degrees C. Marked increases of the average fluoride mission rate from 57.2% to 85.4% of soil total fluoride were noticed as the heating temperature was increased from 700 to 1,100 degrees C. It was found that the major proportion (over 50%) of the soil total fluoride was emitted from soils at approximate 800 degrees C. The amount of fluoride released into the atmosphere when heated depended on the total fluoride contents in the soils. Correlation analysis showed that the soil composition, such as cation exchange capacity, exchangeable calcium and CaCO3, had some influence on fluoride emission below 900 degrees C, but had no influence at temperatures above 900 degrees C. Addition of four calcium compounds (CaO, CaCO3, Ca(OH)2, and CaSO4) at 1.5% by weight raised the temperature at which fluoride began to be released to 700 degrees C. The greatest decrease in fluoride emission among the four calcium compound treatments was found with CaCO3.

  10. Uses of sodium fluoride varnish in dental practice.

    PubMed

    Chu, C H; Lo, Edward

    2008-06-01

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

  11. Atomic force microscopic comparison of remineralization with casein-phosphopeptide amorphous calcium phosphate paste, acidulated phosphate fluoride gel and iron supplement in primary and permanent teeth: An in-vitro study

    PubMed Central

    Agrawal, Nikita; Shashikiran, N. D.; Singla, Shilpy; Ravi, K. S.; Kulkarni, Vinaya Kumar

    2014-01-01

    Context: Demineralization of tooth by erosion is caused by frequent contact between the tooth surface and acids present in soft drinks. Aim: The present study objective was to evaluate the remineralization potential of casein-phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste, 1.23% acidulated phosphate fluoride (APF) gel and iron supplement on dental erosion by soft drinks in human primary and permanent enamel using atomic force microscopy (AFM). Materials and Methods: Specimens were made from extracted 15 primary and 15 permanent teeth which were randomly divided into three treatment groups: CPP-ACP paste, APF gel and iron supplement. AFM was used for baseline readings followed by demineralization and remineralization cycle. Results and Statistics: Almost all group of samples showed remineralization that is a reduction in surface roughness which was higher with CPP-ACP paste. Statistical analysis was performed using by one-way ANOVA and Mann-Whitney U-test with P < 0.05. Conclusions: It can be concluded that the application of CPP-ACP paste is effective on preventing dental erosion from soft drinks. PMID:24808700

  12. The nature of Earth's building blocks as revealed by calcium isotopes

    NASA Astrophysics Data System (ADS)

    Valdes, Maria C.; Moreira, Manuel; Foriel, Julien; Moynier, Frédéric

    2014-05-01

    Calcium is the fifth most abundant element in the Earth and in chondrites and is a pure lithophile element which does not partition into planetary cores. Therefore, the calcium isotopic composition of the mantle represents the bulk Earth and calcium isotopes have the potential to reveal genetic links between Earth and meteorites. However, whether calcium exhibits significant mass-dependent variations among Earth and the various chondrite groups, and the magnitude of these variations, is still contentious. Here we have developed a new method to analyze calcium isotope ratios with high precision using multiple-collector inductively-coupled-plasma mass-spectrometry. The method has been applied to a range of terrestrial and meteoritic samples. We find that the Earth, the Moon, and the aubrite parent body are indistinguishable from enstatite, ordinary, and CO chondritic meteorites. Therefore, enstatite chondrites cannot be excluded as components of Earth's building blocks based on calcium isotopes, as has been proposed previously. In contrast, CI, CV, CM and CR carbonaceous chondrites are largely enriched in lighter calcium isotopes compared to Earth, and, overall, exhibit a wide range in calcium isotopic composition. Calcium is the only major element, along with oxygen, for which isotopic variations are observed among carbonaceous chondrite groups. These calcium isotope variations cannot be attributed to volatility effects, and it is difficult to ascribe them to the abundance of isotopically light refractory inclusions. The calcium isotope data presented in this study suggest that both ordinary and enstatite chondrites are representative of the bulk of the refractory materials that formed Earth. On the basis of calcium isotopes, carbonaceous chondrites (with the exception of CO) are not representative of the fraction of condensable material that accreted to form the terrestrial planets and can be excluded as unique contenders for the building blocks of Earth; however

  13. Electrochemical behavior and corrosion resistance of Ti-15Mo alloy in naturally-aerated solutions, containing chloride and fluoride ions.

    PubMed

    Rodrigues, A V; Oliveira, N T C; dos Santos, M L; Guastaldi, A C

    2015-01-01

    The electrochemical behavior and corrosion resistance of Ti-15Mo alloy to applications as biomaterials in solutions 0.15 mol L(-1) Ringer, 0.15 mol L(-1) Ringer plus 0.036 mol L(-1) NaF and 0.036 mol L(-1) NaF (containing 1,500 ppm of fluoride ions, F(-)) were investigated using open-circuit potential, cyclic voltammetry, and electrochemical impedance spectroscopy techniques, X-ray photoelectron spectroscopy and scanning electron microscope. Corrosion resistance and electrochemical stability of the Ti-15Mo alloy decreased in solutions containing F(-) ions. In all cases, there were formation and growth of TiO2 and MoO3 (a protector film), not being observed pitting corrosion, which might enable Ti-15Mo alloys to be used as biomedical implant, at least in the studied conditions, since the electrochemical stability and corrosion resistance of the passive films formed are necessary conditions for osseointegration.

  14. Removal of fluoride from fluoride contaminated industrial waste water by electrolysis.

    PubMed

    Joshi, Vijaya A; Nanoti, Madan V

    2003-01-01

    Wastewater containing fluoride are generally treated with lime or calcium salt supplemented with aluminium salts. Wastewater generated from different industries does not always behave in the same way due to the presence of interfering contaminants. A number of techniques have been developed and studied for the removal of excessive fluoride. Most of these are based on use of aluminium salt. In alum coagulation the sorption properties of product of hydrolysis of aluminium salts and capacity of fluoride for complex formation plays a very important role. These hydrolysis products of aluminium can be produced by passing direct current through aluminium electrode. The text presented in the paper deals with the various aspect of removal of fluoride by electrolysis using aluminium electrode from fluoride chemical based industrial wastewater. PMID:14672366

  15. Cellular lightweight concrete containing high-calcium fly ash and natural zeolite

    NASA Astrophysics Data System (ADS)

    Jitchaiyaphum, Khamphee; Sinsiri, Theerawat; Jaturapitakkul, Chai; Chindaprasirt, Prinya

    2013-05-01

    Cellular lightweight concrete (CLC) with the controlled density of approximately 800 kg/m3 was made from a preformed foam, Type-I Portland cement (OPC), fly ash (FA), or natural zeolite (NZ), and its compressive strength, setting time, water absorption, and microstructure of were tested. High-calcium FA and NZ with the median particle sizes of 14.52 and 7.72 μm, respectively, were used to partially replace OPC at 0, 10wt%, 20wt%, and 30wt% of the binder (OPC and pozzolan admixture). A water-to-binder mass ratio (W/B) of 0.5 was used for all mixes. The testing results indicated that CLC containing 10wt% NZ had the highest compressive strength. The replacement of OPC with NZ decreased the total porosity and air void size but increased the capillary porosity of the CLC. The incorporation of a suitable amount of NZ decreased the setting time, total porosity, and pore size of the paste compared with the findings with the same amount of FA. The total porosity and cumulative pore volume decreased, whereas the gel and capillary pores increased as a result of adding both pozzolans at all replacement levels. The water absorption increased as the capillary porosity increased; this effect depended on the volume of air entrained and the type or amount of pozzolan.

  16. Mechanochemical dissociation of calcium carbonate: laboratory data and relation to natural emissions of CO 2

    NASA Astrophysics Data System (ADS)

    Martinelli, Giovanni; Plescia, Paolo

    2004-05-01

    This paper investigates the possible role of mechanochemical CO 2 production due to stimulation from the action of friction on calcite. This experimentation has two objectives: firstly, to obtain information on the effect of the mechanical disassociation of carbon dioxide from the carbonates and, secondly, to simulate the conditions that may arise during a tectonic action. The action of disassociation has been observed on pure calcium carbonate from analyses ground at different times in a ring-roller mill. The ring-roller mill is a grinding system that mainly works through friction and, to a lesser extent, by non-hydrostatic compression. It has been observed that the grinding action determines an abundant release of carbon dioxide, with a non-linear trend that emulates the trend in the decrease in crystallinity. This indicates a close connection between crystallinity and the dissociation of carbonate. The Authors hypothesize a carbon dioxide release mechanism linked to the factures induced by the friction and the increase in the structural disorder induced in the lattice by the plastic sliding. This mechanism could play an important role in the natural release of CO 2, along with the other carbon dioxide sources that are already known of.

  17. The effective use of fluorides in public health.

    PubMed Central

    Jones, Sheila; Burt, Brian A.; Petersen, Poul Erik; Lennon, Michael A.

    2005-01-01

    Dental caries remain a public health problem for many developing countries and for underprivileged populations in developed countries. This paper outlines the historical development of public health approaches to the use of fluoride and comments on their effectiveness. Early research and development was concerned with waterborne fluorides, both naturally occurring and added, and their effects on the prevalence and incidence of dental caries and dental fluorosis. In the latter half of the 20th century, the focus of research was on fluoride toothpastes and mouth rinses. More recently, systematic reviews summarizing these extensive databases have indicated that water fluoridation and fluoride toothpastes both substantially reduce the prevalence and incidence of dental caries. We present four case studies that illustrate the use of fluoride in modern public health practice, focusing on: recent water fluoridation schemes in California, USA; salt fluoridation in Jamaica; milk fluoridation in Chile; and the development of "affordable" fluoride toothpastes in Indonesia. Common themes are the concern to reduce demands for compliance with fluoride regimes that rely upon action by individuals and their families, and the issue of cost. We recommend that a community should use no more than one systemic fluoride (i.e. water or salt or milk fluoridation) combined with the use of fluoride toothpastes, and that the prevalence of dental fluorosis should be monitored in order to detect increases in or higher-than-acceptable levels. PMID:16211158

  18. [Comparative in vitro evaluation of modern glass ionomer cements for adhesion strength and fluoride release].

    PubMed

    Zhitkov, M Yu; Rusanov, F S; Poyurovskaya, I Ya

    2016-01-01

    The study proved similar adhesion strength and fluoride release level in aqueous extracts of glass ionomer cements Cemion (VladMiVa, Russia), Glassin Rest (Omega-Dent, Russia), Cemfil 10 (StomaDent, Russia) and Fuji VIII (GC Corporation, Japan). Despite of close concentrations of fluoride in glasses, the rate of fluoride release in water from calcium and calcium-barium glasses is much higher than that of strontium glasses. PMID:27239999

  19. How Does Fluoride Work?

    MedlinePlus

    ... Help White House Lunch Recipes How Does Fluoride Work? KidsHealth > For Kids > How Does Fluoride Work? Print A A A Text Size There's fluoride ... even in your water. But how does it work to keep teeth healthy? Let's find out. Fluoride ...

  20. Review of fluoride removal from drinking water.

    PubMed

    Mohapatra, M; Anand, S; Mishra, B K; Giles, Dion E; Singh, P

    2009-10-01

    Fluoride in drinking water has a profound effect on teeth and bones. Up to a small level (1-1.5mg/L) this strengthens the enamel. Concentrations in the range of 1.5-4 mg/L result in dental fluorosis whereas with prolonged exposure at still higher fluoride concentrations (4-10mg/L) dental fluorosis progresses to skeletal fluorosis. High fluoride concentrations in groundwater, up to more than 30 mg/L, occur widely, in many parts of the world. This review article is aimed at providing precise information on efforts made by various researchers in the field of fluoride removal for drinking water. The fluoride removal has been broadly divided in two sections dealing with membrane and adsorption techniques. Under the membrane techniques reverse osmosis, nanofiltration, dialysis and electro-dialysis have been discussed. Adsorption, which is a conventional technique, deals with adsorbents such as: alumina/aluminium based materials, clays and soils, calcium based minerals, synthetic compounds and carbon based materials. Studies on fluoride removal from aqueous solutions using various reversed zeolites, modified zeolites and ion exchange resins based on cross-linked polystyrene are reviewed. During the last few years, layered double oxides have been of interest as adsorbents for fluoride removal. Such recent developments have been briefly discussed.

  1. A glass-encapsulated calcium phosphate wasteform for the immobilization of actinide-, fluoride-, and chloride-containing radioactive wastes from the pyrochemical reprocessing of plutonium metal

    NASA Astrophysics Data System (ADS)

    Donald, I. W.; Metcalfe, B. L.; Fong, S. K.; Gerrard, L. A.; Strachan, D. M.; Scheele, R. D.

    2007-03-01

    Chloride-containing radioactive wastes are generated during the pyrochemical reprocessing of Pu metal. Immobilization of these wastes in borosilicate glass or Synroc-type ceramics is not feasible due to the very low solubility of chlorides in these hosts. Alternative candidates have therefore been sought including phosphate-based glasses, crystalline ceramics and hybrid glass/ceramic systems. These studies have shown that high losses of chloride or evolution of chlorine gas from the melt make vitrification an unacceptable solution unless suitable off-gas treatment facilities capable of dealing with these corrosive by-products are available. On the other hand, both sodium aluminosilicate and calcium phosphate ceramics are capable of retaining chloride in stable mineral phases, which include sodalite, Na 8(AlSiO 4) 6Cl 2, chlorapatite, Ca 5(PO 4) 3Cl, and spodiosite, Ca 2(PO 4)Cl. The immobilization process developed in this study involves a solid state process in which waste and precursor powders are mixed and reacted in air at temperatures in the range 700-800 °C. The ceramic products are non-hygroscopic free-flowing powders that only require encapsulation in a relatively low melting temperature phosphate-based glass to produce a monolithic wasteform suitable for storage and ultimate disposal.

  2. Direct estimates of natural selection in Iberia indicate calcium absorption was not the only driver of lactase persistence in Europe.

    PubMed

    Sverrisdóttir, Oddny Ósk; Timpson, Adrian; Toombs, Jamie; Lecoeur, Cecile; Froguel, Philippe; Carretero, Jose Miguel; Arsuaga Ferreras, Juan Luis; Götherström, Anders; Thomas, Mark G

    2014-04-01

    Lactase persistence (LP) is a genetically determined trait whereby the enzyme lactase is expressed throughout adult life. Lactase is necessary for the digestion of lactose--the main carbohydrate in milk--and its production is downregulated after the weaning period in most humans and all other mammals studied. Several sources of evidence indicate that LP has evolved independently, in different parts of the world over the last 10,000 years, and has been subject to strong natural selection in dairying populations. In Europeans, LP is strongly associated with, and probably caused by, a single C to T mutation 13,910 bp upstream of the lactase (LCT) gene (-13,910*T). Despite a considerable body of research, the reasons why LP should provide such a strong selective advantage remain poorly understood. In this study, we examine one of the most widely cited hypotheses for selection on LP--that fresh milk consumption supplemented the poor vitamin D and calcium status of northern Europe's early farmers (the calcium assimilation hypothesis). We do this by testing for natural selection on -13,910*T using ancient DNA data from the skeletal remains of eight late Neolithic Iberian individuals, whom we would not expect to have poor vitamin D and calcium status because of relatively high incident UVB light levels. None of the eight samples successfully typed in the study had the derived T-allele. In addition, we reanalyze published data from French Neolithic remains to both test for population continuity and further examine the evolution of LP in the region. Using simulations that accommodate genetic drift, natural selection, uncertainty in calibrated radiocarbon dates, and sampling error, we find that natural selection is still required to explain the observed increase in allele frequency. We conclude that the calcium assimilation hypothesis is insufficient to explain the spread of LP in Europe. PMID:24448642

  3. Direct estimates of natural selection in Iberia indicate calcium absorption was not the only driver of lactase persistence in Europe.

    PubMed

    Sverrisdóttir, Oddny Ósk; Timpson, Adrian; Toombs, Jamie; Lecoeur, Cecile; Froguel, Philippe; Carretero, Jose Miguel; Arsuaga Ferreras, Juan Luis; Götherström, Anders; Thomas, Mark G

    2014-04-01

    Lactase persistence (LP) is a genetically determined trait whereby the enzyme lactase is expressed throughout adult life. Lactase is necessary for the digestion of lactose--the main carbohydrate in milk--and its production is downregulated after the weaning period in most humans and all other mammals studied. Several sources of evidence indicate that LP has evolved independently, in different parts of the world over the last 10,000 years, and has been subject to strong natural selection in dairying populations. In Europeans, LP is strongly associated with, and probably caused by, a single C to T mutation 13,910 bp upstream of the lactase (LCT) gene (-13,910*T). Despite a considerable body of research, the reasons why LP should provide such a strong selective advantage remain poorly understood. In this study, we examine one of the most widely cited hypotheses for selection on LP--that fresh milk consumption supplemented the poor vitamin D and calcium status of northern Europe's early farmers (the calcium assimilation hypothesis). We do this by testing for natural selection on -13,910*T using ancient DNA data from the skeletal remains of eight late Neolithic Iberian individuals, whom we would not expect to have poor vitamin D and calcium status because of relatively high incident UVB light levels. None of the eight samples successfully typed in the study had the derived T-allele. In addition, we reanalyze published data from French Neolithic remains to both test for population continuity and further examine the evolution of LP in the region. Using simulations that accommodate genetic drift, natural selection, uncertainty in calibrated radiocarbon dates, and sampling error, we find that natural selection is still required to explain the observed increase in allele frequency. We conclude that the calcium assimilation hypothesis is insufficient to explain the spread of LP in Europe.

  4. Influence of the surfactant nature on the calcium carbonate synthesis in water-in-oil emulsion

    NASA Astrophysics Data System (ADS)

    Szcześ, Aleksandra

    2009-02-01

    Calcium carbonate has been precipitated from water-in-oil emulsions consisting of n-hexane/nonionic surfactant (Brij 30) and its mixture with cationic (DTAB) or anionic surfactant (SDS) to which calcium chloride and sodium carbonate were added. It was found that the surfactant kind and its amount can regulate the size, form and morphology of the precipitated particles. In case of nonionic surfactant the water/surfactant ratio is the most important parameter that allows to obtain small and regular calcium carbonate crystals. Addition of the DTAB results in different morphology of particles having the same crystal form, whereas addition of SDS changes the kind of emulsion from water-in-oil to oil-in-water. Moreover, light transmittance and backscattering light measurements have been used as a method to study the kinetics of calcium carbonate precipitation in emulsion systems.

  5. Natural and anthropogenic drivers of calcium depletion in a northern forest during the last millennium

    PubMed Central

    Leys, Bérangère A.; Likens, Gene E.; Craine, Joseph M.; Lacroix, Brice; McLauchlan, Kendra K.

    2016-01-01

    The pace and degree of nutrient limitation are among the most critical uncertainties in predicting terrestrial ecosystem responses to global change. In the northeastern United States, forest growth has recently declined along with decreased soil calcium (Ca) availability, suggesting that acid rain has depleted soil Ca to the point where it may be a limiting nutrient. However, it is unknown whether the past 60 y of changes in Ca availability are strictly anthropogenic or partly a natural consequence of long-term ecosystem development. Here, we report a high-resolution millennial-scale record of Ca and 16 other elements from the sediments of Mirror Lake, a 15-ha lake in the White Mountains of New Hampshire surrounded by northern hardwood forest. We found that sedimentary Ca concentrations had been declining steadily for 900 y before regional Euro-American settlement. This Ca decline was not a result of serial episodic disturbances but instead the gradual weathering of soils and soil Ca availability. As Ca availability was declining, nitrogen availability concurrently was increasing. These data indicate that nutrient availability on base-poor, parent materials is sensitive to acidifying processes on millennial timescales. Forest harvesting and acid rain in the postsettlement period mobilized significant amounts of Ca from watershed soils, but these effects were exacerbated by the long-term pattern. Shifting nutrient limitation can potentially occur within 10,000 y of ecosystem development, which alters our assessments of the speed and trajectory of nutrient limitation in forests, and could require reformulation of global models of forest productivity. PMID:27298361

  6. Natural and anthropogenic drivers of calcium depletion in a northern forest during the last millennium.

    PubMed

    Leys, Bérangère A; Likens, Gene E; Johnson, Chris E; Craine, Joseph M; Lacroix, Brice; McLauchlan, Kendra K

    2016-06-21

    The pace and degree of nutrient limitation are among the most critical uncertainties in predicting terrestrial ecosystem responses to global change. In the northeastern United States, forest growth has recently declined along with decreased soil calcium (Ca) availability, suggesting that acid rain has depleted soil Ca to the point where it may be a limiting nutrient. However, it is unknown whether the past 60 y of changes in Ca availability are strictly anthropogenic or partly a natural consequence of long-term ecosystem development. Here, we report a high-resolution millennial-scale record of Ca and 16 other elements from the sediments of Mirror Lake, a 15-ha lake in the White Mountains of New Hampshire surrounded by northern hardwood forest. We found that sedimentary Ca concentrations had been declining steadily for 900 y before regional Euro-American settlement. This Ca decline was not a result of serial episodic disturbances but instead the gradual weathering of soils and soil Ca availability. As Ca availability was declining, nitrogen availability concurrently was increasing. These data indicate that nutrient availability on base-poor, parent materials is sensitive to acidifying processes on millennial timescales. Forest harvesting and acid rain in the postsettlement period mobilized significant amounts of Ca from watershed soils, but these effects were exacerbated by the long-term pattern. Shifting nutrient limitation can potentially occur within 10,000 y of ecosystem development, which alters our assessments of the speed and trajectory of nutrient limitation in forests, and could require reformulation of global models of forest productivity. PMID:27298361

  7. Natural and anthropogenic drivers of calcium depletion in a northern forest during the last millennium.

    PubMed

    Leys, Bérangère A; Likens, Gene E; Johnson, Chris E; Craine, Joseph M; Lacroix, Brice; McLauchlan, Kendra K

    2016-06-21

    The pace and degree of nutrient limitation are among the most critical uncertainties in predicting terrestrial ecosystem responses to global change. In the northeastern United States, forest growth has recently declined along with decreased soil calcium (Ca) availability, suggesting that acid rain has depleted soil Ca to the point where it may be a limiting nutrient. However, it is unknown whether the past 60 y of changes in Ca availability are strictly anthropogenic or partly a natural consequence of long-term ecosystem development. Here, we report a high-resolution millennial-scale record of Ca and 16 other elements from the sediments of Mirror Lake, a 15-ha lake in the White Mountains of New Hampshire surrounded by northern hardwood forest. We found that sedimentary Ca concentrations had been declining steadily for 900 y before regional Euro-American settlement. This Ca decline was not a result of serial episodic disturbances but instead the gradual weathering of soils and soil Ca availability. As Ca availability was declining, nitrogen availability concurrently was increasing. These data indicate that nutrient availability on base-poor, parent materials is sensitive to acidifying processes on millennial timescales. Forest harvesting and acid rain in the postsettlement period mobilized significant amounts of Ca from watershed soils, but these effects were exacerbated by the long-term pattern. Shifting nutrient limitation can potentially occur within 10,000 y of ecosystem development, which alters our assessments of the speed and trajectory of nutrient limitation in forests, and could require reformulation of global models of forest productivity.

  8. Gramicidin D enhances the antibacterial activity of fluoride.

    PubMed

    Nelson, James W; Zhou, Zhiyuan; Breaker, Ronald R

    2014-07-01

    Fluoride is a toxic anion found in many natural environments. One of the major bacterial defenses against fluoride is the cell envelope, which limits passage of the membrane-impermeant fluoride anion. Accordingly, compounds that enhance the permeability of bacterial membranes to fluoride should also enhance fluoride toxicity. In this study, we demonstrate that the pore-forming antibiotic gramicidin D increases fluoride uptake in Bacillus subtilis and that the antibacterial activity of this compound is potentiated by fluoride. Polymyxin B, another membrane-targeting antibiotic with a different mechanism of action, shows no such improvement. These results, along with previous findings, indicate that certain compounds that destabilize bacterial cell envelopes can enhance the toxicity of fluoride.

  9. Fluoride stimulates ( sup 3 H)thymidine incorporation and alkaline phosphatase production by human osteoblasts

    SciTech Connect

    Khokher, M.A.; Dandona, P. )

    1990-11-01

    The effect of sodium fluoride on alkaline phosphatase (ALP) release and ({sup 3}H)thymidine uptake by human osteoblasts in culture was investigated. Sodium fluoride stimulated both ALP release and ({sup 3}H)thymidine uptake at concentrations of sodium fluoride greater than 250 mumol/L. This stimulation was similar in magnitude to that induced by 1,25-dihydroxycholecalciferol. The fluoride-induced increase in ALP was inhibited by verapamil, a calcium channel blocker. We conclude that sodium fluoride stimulates osteoblasts to proliferate and to release ALP. This stimulation by fluoride is dependent on calcium influx. Fluoride-induced stimulation of human osteoblasts may be relevant to its effect in enhancing bone formation in patients with osteoporosis.

  10. Similar healthy osteoclast and osteoblast activity on nanocrystalline hydroxyapatite and nanoparticles of tri-calcium phosphate compared to natural bone.

    PubMed

    MacMillan, Adam K; Lamberti, Francis V; Moulton, Julia N; Geilich, Benjamin M; Webster, Thomas J

    2014-01-01

    While there have been numerous studies to determine osteoblast (bone forming cell) functions on nanocrystalline compared to micron crystalline ceramics, there have been few studies which have examined osteoclast activity (including tartrate-resistant acid phosphatase, formation of resorption pits, size of resorption pits, and receptor activator of nuclear factor κB [RANK]). This is despite the fact that osteoclasts are an important part of maintaining healthy bone since they resorb bone during the bone remodeling process. Moreover, while it is now well documented that bone formation is enhanced on nanoceramics compared to micron ceramics, some have pondered whether osteoblast functions (such as osteoprotegerin and RANK ligand [RANKL]) are normal (ie, non-diseased) on such materials compared to natural bone. For these reasons, the objective of the present in vitro study was to determine various functions of osteoclasts and osteoblasts on nanocrystalline and micron crystalline hydroxyapatite as well as tri-calcium phosphate materials and compare such results to cortical and cancellous bone. Results showed for the first time similar osteoclast activity (including tartrate-resistant acid phosphatase, formation of resorption pits, size of resorption pits, and RANK) and osteoblast activity (osteoprotegerin and RANKL) on nanocrystalline hydroxyapatite compared to natural bone, whereas osteoclast and osteoblast functions on micron crystalline versions of these ceramics were much different than natural bone. In this manner, this study provides additional evidence that nanocrystalline calcium phosphates can serve as suitable synthetic analogs to natural bone to improve numerous orthopedic applications. It also provides the first data of healthy osteoclast and osteoblast functions on nanocrystalline calcium phosphates compared to natural bone.

  11. Similar healthy osteoclast and osteoblast activity on nanocrystalline hydroxyapatite and nanoparticles of tri-calcium phosphate compared to natural bone

    PubMed Central

    MacMillan, Adam K; Lamberti, Francis V; Moulton, Julia N; Geilich, Benjamin M; Webster, Thomas J

    2014-01-01

    While there have been numerous studies to determine osteoblast (bone forming cell) functions on nanocrystalline compared to micron crystalline ceramics, there have been few studies which have examined osteoclast activity (including tartrate-resistant acid phosphatase, formation of resorption pits, size of resorption pits, and receptor activator of nuclear factor κB [RANK]). This is despite the fact that osteoclasts are an important part of maintaining healthy bone since they resorb bone during the bone remodeling process. Moreover, while it is now well documented that bone formation is enhanced on nanoceramics compared to micron ceramics, some have pondered whether osteoblast functions (such as osteoprotegerin and RANK ligand [RANKL]) are normal (ie, non-diseased) on such materials compared to natural bone. For these reasons, the objective of the present in vitro study was to determine various functions of osteoclasts and osteoblasts on nanocrystalline and micron crystalline hydroxyapatite as well as tri-calcium phosphate materials and compare such results to cortical and cancellous bone. Results showed for the first time similar osteoclast activity (including tartrate-resistant acid phosphatase, formation of resorption pits, size of resorption pits, and RANK) and osteoblast activity (osteoprotegerin and RANKL) on nanocrystalline hydroxyapatite compared to natural bone, whereas osteoclast and osteoblast functions on micron crystalline versions of these ceramics were much different than natural bone. In this manner, this study provides additional evidence that nanocrystalline calcium phosphates can serve as suitable synthetic analogs to natural bone to improve numerous orthopedic applications. It also provides the first data of healthy osteoclast and osteoblast functions on nanocrystalline calcium phosphates compared to natural bone. PMID:25506216

  12. Fluoride and Water (For Parents)

    MedlinePlus

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

  13. Dental enamel around fixed orthodontic appliances after fluoride varnish application.

    PubMed

    Gontijo, Leonardo; Cruz, Roberval de Almeida; Brandão, Paulo Roberto Gomes

    2007-01-01

    Poor oral hygiene has been considered one of the main problems routinely faced in the orthodontic treatment. Orthodontic appliance creates an environment that provides mineral loss from the dental enamel. Such condition is clinically seen as white spot lesions and cavitations in the most severe cases. The aim of this study was to evaluate the effects of a fluoride varnish application as a caries prevention method for clinical orthodontics. The experiment analyzed dental enamel adjacent to orthodontics accessories after treatment. In addition, it was observed the calcium, phosphorus and fluoride contents on enamel treated with a fluoride varnish. The results showed that fluoride varnish application is a simple and fast technique that could be useful in preventing enamel demineralization associated to orthodontic treatment. Scanning electron microscopy revealed significant amount of calcium fluoride-like material deposited on enamel and energy dispersive x-ray analysis demonstrated a large incorporation of calcium and fluoride to the enamel of the treated specimens. It was concluded that fluoride varnish could indeed be considered an efficient preventive method to enhance enamel resistance against the cariogenic challenges during orthodontic therapy.

  14. Preparation and pre-characterization of epoxidized natural rubber (ENR) / poly(vinylidene fluoride) (PVDF) (ENR/PVDF) thin film composite membrane

    NASA Astrophysics Data System (ADS)

    Mod, Norliyana; Othaman, Rizafizah

    2015-09-01

    Epoxidised Natural Rubber (ENR) / Poly (Vinylidene Fluoride) (PVDF) (ENR/PVDF) (60:40 wt%) thin film composite membrane was prepared by using solution casting technique. The focuses of this paper are to prepare ENR/PVDF membrane with ratio of ENR to PVDF 60:40 wt%, and to study the effectiveness of treating Palm Oil Mill Effluent (POME) using the membrane. The prepared membrane was analyzed using optical microscope and the treatment of POME was investigated using dead-end stirred cell. Treated and untreated POME was analyzed to test the percentage of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) removal. Optical microscope micrographs showed that the surface of the membrane was slightly uneven. The rate of flux which passed through the membrane was 0.60 L/hm2. Both BOD and COD decreased by 23.6 % and 49.32 % respectively, after single treatment. This showed that the membrane can be used for POME treatment. The value of BOD and COD removal can be increased by recycling the treated POME for more than two cycles, which will be further studied by authors.

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

    DOEpatents

    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.

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

    PubMed Central

    Kanduti, Domen; Sterbenk, Petra; Artnik, Barbara

    2016-01-01

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

  17. Method for the analysis of total fluoride in fluoride-releasing dental varnishes.

    PubMed

    Carey, C M; Coleman, S S

    2014-01-01

    Today's fluoride-releasing varnishes (F-varnish) contain a wide variety of ingredients which present analytical challenges for measuring their total fluoride content. This study reports improved methods to measure fluoride content in F-varnishes. Six different commercially available F-varnishes that contain difluorosilane (0.1% F) or NaF (2.26% F) alone or in combination with calcium-phosphates were analyzed. In a vial, 1-3 drops (0.05-0.15 g) of varnish product was dispensed, dissolved in chloroform, equilibrated in TISAB and analyzed via fluoride ion-selective electrode. The average weight percentage of fluoride for all F-varnishes containing NaF ranged from 2.03 to 2.24% F, which is within 90% of the declared label concentration of 2.26% F. Analysis of the difluorosilane-containing product required an additional hydrolysis step. ANOVA found no significant difference between the 5% NaF varnishes at p < 0.05. This method for fluoride analysis yields reliable and reproducible results and can be used for a wide variety of F-varnishes. The standard uncertainty for this method is ±4%. This method may become the basis for national and international standards that ensure the F-varnish products used in clinical practice have the fluoride content declared in the product literature.

  18. Impact of uranyl-calcium-carbonato complexes on uranium(VI) adsorption to synthetic and natural sediments

    SciTech Connect

    Stewart, B.D.; Mayes, Melanie; Fendorf, Scott

    2010-01-01

    Adsorption on soil and sediment solids may decrease aqueous uranium concentrations and limit its propensity for migration in natural and contaminated settings. Uranium adsorption will be controlled in large part by its aqueous speciation, with a particular dependence on the presence of dissolved calcium and carbonate. Here we quantify the impact of uranyl speciation on adsorption to both goethite and sediments from the Hanford Clastic Dike and Oak Ridge Melton Branch Ridgetop formations. Hanford sediments were preconditioned with sodium acetate and acetic acid to remove carbonate grains, and Ca and carbonate were reintroduced at defined levels to provide a range of aqueous uranyl species. U(VI) adsorption is directly linked to UO{sub 2}{sup 2+} speciation, with the extent of retention decreasing with formation of ternary uranyl-calcium-carbonato species. Adsorption isotherms under the conditions studied are linear, and K{sub d} values decrease from 48 to 17 L kg{sup -1} for goethite, from 64 to 29 L kg{sup -1} for Hanford sediments, and from 95 to 51 L kg{sup -1} for Melton Branch sediments as the Ca concentration increases from 0 to 1 mM at pH 7. Our observations reveal that, in carbonate-bearing waters, neutral to slightly acidic pH values ({approx}5) and limited dissolved calcium are optimal for uranium adsorption.

  19. Fluoride uptake and inhibition of intra-oral demineralization, following the application of varnishes with different concentrations of fluoride.

    PubMed

    de Bruyn, H; Buskes, J A; Jongebloed, W; Arends, J

    1988-06-01

    The relationship between the amount of fluoride acquired by human enamel after varnish application and the resulting inhibition demineralization of is presented and discussed. Intact human enamel was pretreated with Fluor Protector varnishes with differing fluoride contents (0.7; 0.1; 0.05 and 0 wt% F-) for 24 hours. In a first experiment the amount of fluoride acquired after application was determined. In a second experiment the pretreated enamel was stored intra-orally under constant plaque coverage, in order to create a substantial demineralization challenge. The protection against demineralization, induced by the various varnishes was determined four months after varnish application using microradiography. Under the cariogenic conditions created in this study, the fluoride containing varnishes induced a protection of 53-75%. Although the amount of fluoride uptake was strongly related to the fluoride content in the varnishes, no statistically significant difference in demineralization inhibition between the varnishes was observed. SEM investigation of the enamel lesions revealed globular precipitates inside the fluoridated enamel, presumably consisting of calcium fluoride-like material. The present study indicates that the fluoride content in Fluor Protector varnishes can be decreased without reducing its ability to inhibit demineralization.

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

    PubMed Central

    MOIMAZ, Suzely Adas Saliba; SALIBA, Nemre Adas; SALIBA, Orlando; SUMIDA, Doris Hissako; de SOUZA, Neila Paula; CHIBA, Fernando Yamamoto; GARBIN, Cléa Adas Saliba

    2013-01-01

    Objectives: Fluoride levels in the public water supplies of 40 Brazilian cities were analyzed and classified on the basis of risk/benefit balance. Material and Methods: Samples were collected monthly over a seven-year period from three sites for each water supply source. The samples were analyzed in duplicate in the laboratory of the Center for Research in Public Health - UNESP using an ion analyzer coupled to a fluoride-specific electrode. Results: A total of 19,533 samples were analyzed, of which 18,847 were artificially fluoridated and 686 were not artificially fluoridated. In samples from cities performing water fluoridation, 51.57% (n=9,720) had fluoride levels in the range of 0.55 to 0.84 mg F/L; 30.53% (n=5,754) were below 0.55 mg F/L and 17.90% (n=3,373) were above 0.84 mg F/L (maximum concentration=6.96 mg F/L). Most of the cities performing fluoridation that had a majority of samples with fluoride levels above the recommended parameter had deep wells and more than one source of water supply. There was some variability in the fluoride levels of samples from the same site and between collection sites in the same city. Conclusions: The majority of samples from cities performing fluoridation had fluoride levels within the range that provides the best combination of risks and benefits, minimizing the risk of dental fluorosis while preventing dental caries. The conduction of studies about water distribution systems is suggested in cities with high natural fluoride concentrations in order to optimize the use of natural fluoride for fluoridation costs and avoid the risk of dental fluorosis. PMID:23559106

  1. Prevention of enamel demineralization with a novel fluoride strip: enamel surface composition and depth profile

    PubMed Central

    Lee, Bor-Shiunn; Chou, Po-Hung; Chen, Shu-Yu; Liao, Hua-Yang; Chang, Che-Chen

    2015-01-01

    There is no topically applicable low concentration fluoride delivery device available for caries prevention. This study was aimed to assess the use of a low concentration (1450 ppm) fluoride strip as an effective fluoride delivery system against enamel demineralization. The enamel surface composition and calcium-deficient hydroxyapatite or toothpaste treatments were investigated using X-ray photoelectron spectroscopy. In vitro enamel demineralization was assayed using a pH cycling model and the dissolution of calcium ions from the treated specimens was quantified using ion chromatography. After 24-hr fluoride-strip treatment, the enamel was covered with a CaF2 layer which showed a granular morphology of 1 μm in size. Below the CaF2 layer was a region of mixed fluorapatite and CaF2. Fluoride infiltrated extensively in enamel to produce highly fluorinated fluorohydroxyapatite. In comparison, low-fluoride-level fluorinated fluorohydroxyapatite was formed on the enamel specimen exposed to toothpaste. The treatments with the fluoride strip as short as 1 hr significantly inhibited enamel demineralization. The fluoride strip was effective for topical fluoride delivery and inhibited in vitro demineralization of enamel by forming CaF2 and fluoride-containing apatites at the enamel surface. It exhibited the potential as an effective fluoride delivery device for general use in prevention of caries. PMID:26293361

  2. Effect of ACP-CPP Chewing Gum and Natural Chewable Products on Plaque pH, Calcium and Phosphate Concentration

    PubMed Central

    Sultan, Saima; Chaudhary, Seema; Manuja, Naveen; Kaur, Harsimran; Amit, Sinha Ashish; Lingesha, Ravishankar Telgi

    2016-01-01

    Introduction Numerous epidemiological studies have documented dental caries as the major public health problems throughout the world. It is gradually increasing in the underdeveloped and developing countries especially in children due to increasing popularity of refined sugars. Aim The aim of the study was to evaluate the effect of natural chewable products (Tulsi, sesame seeds, fennel seeds, coconut) and ACP-CPP chewing gum on plaque pH, calcium and phosphate concentration. Materials and Methods A randomized controlled trial, with a cross-over study design, was conducted. Ten subjects aged 15-17 years who agreed to refrain from oral hygiene practice for 48 hours prior to the sample collection were selected for the study. The baseline plaque pH, calcium and phosphate was measured and repeated after 5 and 30 minutes. It was ensured that each study participant was subjected to all the products making an effective sample of ten subjects per product. The data was statistically analysed. Results The mean pH in all the study groups increased after 5 minutes and 30 minutes compared to baseline, except for coconut group at 30 minutes and fennel group at 5 minutes. Highest increase in plaque calcium concentration was found in fennel group followed by recaldent and sesame, respectively. Whereas, the highest increase in plaque phosphate was found in recaldent group followed by sesame group and fennel group respectively. Conclusion Plant products can be effective, inexpensive, easily accessible methods of maintaining oral health. Further studies are recommended to confirm long term effects. PMID:27190943

  3. Serum Estradiol and Testosterone Levels in Kidney Stones Disease with and without Calcium Oxalate Components in Naturally Postmenopausal Women

    PubMed Central

    Ou, Lili; Duan, Xiaolu; Zeng, Guohua

    2013-01-01

    Objective Epidemiological data reveal that the overall risk for kidney stones disease is lower for women compared to age-matched men. However, the beneficial effect for the female sex is lost upon menopause, a time corresponding to the onset of fall in estrogen levels. The aim of this study was to describe the serum estradiol (E2) and testosterone (T) characteristics of naturally postmenopausal women with kidney stones. Methods 113 naturally postmenopausal women with newly diagnosed kidney stones (aged 57.4±4.98 years) and 84 age frequency matched stone-free controls (56.9±4.56 years) were validly recruited in the case-control study. The odds ratios (ORs) for the associations between sex hormones and kidney stones were estimated with logistic regression models, adjusting for demographic data and medical history. Patients were also stratified analyzed according to stone components (calcium oxalate stones [COS]; non-calcium oxalate stones [NCOS]). Results Serum E2 (21.1 vs. 31.1 pg/ml) was significantly lower in kidney stones patients compared to controls. Post-hoc analysis demonstrated that this effect was driven by COS patients (p<0.001). According to tertiles of the E2 levels, a significant higher frequency of COS was seen in the lowest E2 group (p <0.001). Multiple logistic regression analysis identified E2 level as a strong factor that was independently associated with the risk for COS (per 1 SD increase, OR=0.951, 95% confidence interval [CI] = 0.919-0.985; highest: lowest tertile, OR=0.214, 95%CI = 0.069-0.665). However, serum T levels did not significantly differ among the groups. Conclusions Naturally postmenopausal women with higher remaining estradiol levels appear less likely to suffer from kidney calcium oxalate stones. However, no correlation was found between serum T level and kidney stones. These findings support the hypothesis that higher postmenopausal endogenous estrogens may protect against kidney stones with ageing. PMID:24086550

  4. Natural Abundance 43Ca NMR as a Tool for Exploring Calcium Biomineralization: Renal Stone Formation and Growth

    SciTech Connect

    Bowers, Geoffrey M.; Kirkpatrick, Robert J.

    2011-12-07

    Renal stone diseases are a global health issue with little effective therapeutic recourse aside from surgery and shock-wave lithotripsy, primarily because the fundamental chemical mechanisms behind calcium biomineralization are poorly understood. In this work, we show that natural abundance 43Ca NMR at 21.1 T is an effective means to probe the molecular-level Ca2+ structure in oxalate-based kidney stones. We find that the 43Ca NMR resonance of an authentic oxalate-based kidney stone cannot be explained by a single pure phase of any common Ca2+-bearing stone mineral. Combined with XRD results, our findings suggest an altered calcium oxalate monohydrate-like Ca2+ coordination environment for some fraction of Ca2+ in our sample. The evidence is consistent with existing literature hypothesizing that nonoxalate organic material interacts directly with Ca2+ at stone surfaces and is the primary driver of renal stone aggregation and growth. Our findings show that 43Ca NMR spectroscopy may provide unique and crucial insight into the fundamental chemistry of kidney stone formation, growth, and the role organic molecules play in these processes.

  5. Plasma-sprayed metal-glass fluoride coatings for lubrication to 1170 K (1650 F)

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.

    1974-01-01

    Plasma spray of Nichrome matrix composite contains dispersed glass for oxidation protection and calcium fluoride for lubrication. Coatings can be applied to bearing journals and bearing bores. Coating was easily machinable and had excellent bond strength on substrate metal.

  6. Calcium supplements

    MedlinePlus

    ... TYPES OF CALCIUM SUPPLEMENTS Forms of calcium include: Calcium carbonate: Over-the-counter (OTC) antacid products, such as Tums and Rolaids, contain calcium carbonate. These sources of calcium do not cost much. ...

  7. Solubility of calcium salts of unconjugated and conjugated natural bile acids.

    PubMed

    Gu, J J; Hofmann, A F; Ton-Nu, H T; Schteingart, C D; Mysels, K J

    1992-05-01

    The approximate solubility products of the calcium salts of ten unconjugated bile acids and several taurine conjugated bile acids were determined. The formation of micelles, gels, and/or precipitates in relation to Ca2+,Na+, and bile salt concentration was summarized by "phase maps." Because the ratio of Ca2+ to bile salt in the precipitates was ca. 1:2, and the activity of Ca2+ but not that of bile salt (BA-) could be measured, the ion product of aCa2+ [BA-]2 was calculated. The ion product (= Ksp) ranged over nine orders of magnitude and the solubility thus ranged over three orders of magnitude; its value depended on the number and orientation of the hydroxyl groups in the bile acid. Ion products (in units of 10(-9) mol/l)3 were as follows: cholic (3 alpha OH,7 alpha OH,12 alpha OH) 640; ursocholic (3 alpha OH,7 beta OH,12 alpha OH) 2300; hyocholic (3 alpha OH,6 alpha OH,7 alpha OH) 11; ursodeoxycholic (3 alpha OH,7 beta OH) 91; chenodeoxycholic (3 alpha OH,7 alpha OH) 10; deoxycholic (3 alpha OH,12 alpha OH) 1.5; 12-epideoxycholic (lagodeoxycholic, 3 alpha OH,12 beta OH) 2.2; hyodeoxycholic (3 alpha OH,6 alpha OH) 0.7; and lithocholic (3 alpha OH) 0.00005. The critical micellization temperature of the sodium salt of murideoxycholic acid (3 alpha OH,6 beta OH) was greater than 100 degrees C, and its Ca2+ salt was likely to be very insoluble. Taurine conjugates were much more soluble than their corresponding unconjugated derivatives: chenodeoxycholyltaurine, 384; deoxycholyltaurine, 117; and cholyltaurine, greater than 10,000. Calcium salts of unconjugated bile acids precipitated rapidly in contrast to those of glycine conjugates which were metastable for months. Thus, hepatic conjugation of bile acids with taurine or glycine not only enhances solubility at acidic pH, but also at Ca2+ ion concentrations present in bile and intestinal content.

  8. Effects of Sodium and Hydrogen Flourides on the Metabolism of Flourine, Calcium, and Phosphorus in Rats

    PubMed Central

    Macuch, P.; Kortus, J.; Balazova, G.; Mayer, J.

    1968-01-01

    Rats given 4 mg. fluoride/kg./day for eight days excreted more calcium and phosphorus and retained less than the controls. In bone ash from rats given different fluoride doses for 40 days the calcium and phosphorus were maximal after a total dose of about 250 μg. fluoride/rat, but fell to subnormal levels after higher doses. The calcium and phosphorus levels in bone ash from rats given 750 μg. fluoride/day fell with the duration of treatment. Rats exposed to 9·4-11·7 μg. hydrogen fluoride/litre air absorbed fluoride rapidly, as shown by increased urinary excretion, by changes in the enamel of the teeth, and by rising fluoride levels in the teeth and bones. Radiological examination, however, showed no gross changes. Urinary excretion increased with exposure time. PMID:5647974

  9. Streptozotocin Aggravated Osteopathology and Insulin Induced Osteogenesis Through Co-treatment with Fluoride.

    PubMed

    Yang, Chen; Zhang, Mengmeng; Li, Yagang; Wang, Yan; Mao, Weixian; Gao, Yuan; Xu, Hui

    2015-12-01

    The role of insulin in the mechanism underlying the excessive fluoride that causes skeletal lesion was studied. The in vitro bone marrow stem cells (BMSC) collected from Kunming mice were exposed to varying concentrations of fluoride with or without insulin. The cell viability and early differentiation of BMSC co-treated with fluoride and insulin were measured by using cell counting kit-8 and Gomori modified calcium-cobalt method, respectively. We further investigated the in vivo effects of varying dose of fluoride on rats co-treated with streptozotocin (STZ). Wistar rats were divided into six groups which included normal control, 10 mg fluoride/kg day group, 20 mg fluoride/kg day group, STZ control, STZ+10 mg fluoride/kg day group, and STZ+20 mg fluoride/kg day group. The rats were administered with sodium fluoride (NaF) by gavage with water at doses 10 and 20 mg fluoride/kg day for 2 months. In a period of one month, half of rats in every group were treated with streptozotocin (STZ) once through intraperitoneal injection at 52 mg/kg body weight. The serum glucose, HbA1c, and insulin were determined. Bone mineral content and insulin release were assessed. The results showed insulin combined with fluoride stimulated BMSC cell viability in vitro. The bone mineral content reduced in rats treated with higher dose of fluoride and decreased immensely in rat co-treated with fluoride and STZ. Similarly, a combination treatment of a high dose of fluoride and STZ decreased insulin sensitivity and activity. To sum up, these data indicated fluoride influenced insulin release, activity, and sensitivity. Furthermore, the insulin state in vivo interfered in the osteogenesis in turn and implied there was a close relation between insulin and bone pathogenesis in the mechanism of fluoride toxicity.

  10. Palmitoleic acid calcium salt: a lubricant and bactericidal powder from natural lipids.

    PubMed

    Yamamoto, Yoshiaki; Kawamura, Yuki; Yamazaki, Yuki; Kijima, Tatsuro; Morikawa, Toshiya; Nonomura, Yoshimune

    2015-01-01

    Palmitoleic acid is a promising bactericidal agent for cleansing products with alternative bactericidal abilities. In this study, we focus on the physical and biological activity of palmitoleic acid calcium salt (C16:1 fatty acid Ca salt) because it forms via an ion-exchange reaction between palmitoleic acid and Ca ions in tap water, and remains on the skin surface during the cleansing process. Here, we prepared C16:1 fatty acid Ca salt to investigate its crystal structure and physical and bactericidal properties. The Ca salt was a plate-shaped lamellar crystalline powder with a particle diameter of several micrometers to several tens of micrometers; it exhibited significant lubricity and alternative bactericidal activity against Staphylococcus aureus (S. aureus) and Propionibacterium acnes (P. acnes). We also examined other fatty acid Ca salts prepared from lauric acid (C12:0 fatty acid), palmitic acid (C16:0 fatty acid), and oleic acid (C18:1 fatty acid). The bactericidal activities and lubricity of the fatty acid Ca salts changed with the alkyl chain length and the degree of unsaturation. The C16:1 fatty acid Ca salt exhibited the strongest selective bactericidal ability among the four investigated fatty acid Ca salts. These findings suggest that C16:1 fatty acid and its Ca salt have potential applications in cleansing and cosmetic products. PMID:25757432

  11. Distribution of fluoride in ground water of West Virginia

    USGS Publications Warehouse

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

    1993-01-01

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

  12. Nature and origin of the calcium asymmetry-arising during gravitropic response in etiolated pea epicotyls

    SciTech Connect

    Migliaccio, F.; Galston, A.W.

    1987-10-01

    Seven day old etiolated pea epicotyls were loaded symmetrically with /sup 3/H-indole 3-acetic acid (IAA) or /sup 45/Ca/sup 2 +/, then subjected to 1.5 hours of 1g gravistimulation. Epidermal peels taken from top and bottom surfaces after 90 minutes showed an increase in IAA on the lower side and of Ca/sup 2 +/ on the upper side. Inhibitors of IAA movement (TIBA, 9-hydroxyfluorene carboxylic acid) block the development of both IAA and Ca/sup 2 +/ asymmetries, but substances known to interfere with normal Ca/sup 2 +/ transport do not significantly alter either IAA or Ca/sup 2 +/ asymmetries. These substances, however, are active in modifying both Ca/sup 2 +/ uptake and efflux through oat and pea leaf protoplast membranes. The authors conclude that the /sup 45/Ca/sup 2 +/ fed to pea epicotyls occurs largely in the cell wall, and that auxin movement is primary and Ca/sup 2 +/ movement secondary in gravitropism. They hypothesize that apoplastic Ca/sup 2 +/ changes during the graviresponse because it is displaced by H/sup +/ secreted through auxin-induced proton release. This proposed mechanism is supported by localized pH experiments, in which filter paper soaked in various buffers was applied to one side of a carborundum-abraded epicotyls. Buffer at pH 3 increased calcium loss from the side to which it is applied, whereas pH 7 buffer decreases it. Moreover, 10 micromolar IAA and 1 micromolar fusicoccin, which promote H/sup +/ efflux, increase Ca/sup 2 +/ release from pea epicotyl segments, whereas cycloheximide, which inhibits H/sup +/ efflux, has the reverse effect.

  13. PRODUCTION OF THORIUM FLUORIDE

    DOEpatents

    Zachariasen, W.H.

    1959-08-11

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

  14. Bioavailability of fluoride in drinking water: a human experimental study.

    PubMed

    Maguire, A; Zohouri, F V; Mathers, J C; Steen, I N; Hindmarch, P N; Moynihan, P J

    2005-11-01

    It has been suggested that systemic fluoride absorption from drinking water may be influenced by the type of fluoride compound in the water and by water hardness. Using a human double-blind cross-over trial, we conducted this study to measure c(max), T(max), and Area Under the Curve (AUC) for plasma F concentration against time, following the ingestion of naturally fluoridated hard and soft waters, artificially fluoridated hard and soft waters, and a reference water. Mean AUC over 0 to 8 hours was 1330, 1440, 1679, 1566, and 1328 ng F.min.mL(-1) for naturally fluoridated soft, naturally fluoridated hard, artificially fluoridated soft, artificially fluoridated hard, and reference waters, respectively, with no statistically significant differences among waters for AUC, c(max), or T(max). Any differences in fluoride bioavailability between drinking waters in which fluoride is present naturally or added artificially, or the waters are hard or soft, were small compared with large within- and between-subject variations in F absorption. Abbreviations used: F, fluoride; AUC, Area under the Curve for plasma F concentration against time; AUC(0-3), Area under the Curve for plasma F concentration against time for 0 to 3 hours following water ingestion; AUC(0-8), Area under the Curve for plasma F concentration against time for 0 to 8 hours following water ingestion; c(max), maximum plasma F concentration corrected for baseline plasma F and dose (i.e., F concentration of individual waters); T(max), time of c(max).

  15. Dietary fluoride intake by children receiving different sources of systemic fluoride.

    PubMed

    Rodrigues, M H C; Leite, A L; Arana, A; Villena, R S; Forte, F D S; Sampaio, F C; Buzalaf, M A R

    2009-02-01

    There has been no comparison of fluoride (F) intake by pre-school children receiving more traditional sources of systemic F. The aim of this study was to estimate the dietary F intake by children receiving F from artificially fluoridated water (AFW-Brazil, 0.6-0.8 mg F/L), naturally fluoridated water (NFW-Brazil, 0.6-0.9 mg F/L), fluoridated salt (FS-Peru, 180-200 mg F/Kg), and fluoridated milk (FM-Peru, 0.25 mg F). Children (n=21-26) aged 4-6 yrs old participated in each community. A non-fluoridated community (NoF) was evaluated as the control population. Dietary F intake was monitored by the "duplicate plate" method, with different constituents (water, other beverages, and solids). F was analyzed with an ion-selective electrode. Data were tested by Kruskall-Wallis and Dunn's tests (p<0.05). Mean (+/- SD) F intake (mg/Kg b.w./day) was 0.04+/-0.01(b), 0.06+/-0.02(a,b), 0.05+/-0.02(a,b), 0.06+/-0.01(a), and 0.01+/-0.00(c) for AFW/NFW/FS/FM/NoF, respectively. The main dietary contributors for AFW/NFW and FS/FM/NoF were water and solids, respectively. The results indicate that the dietary F intake must be considered before a systemic method of fluoridation is implemented.

  16. Effect of chemical environment on the dynamics of water confined in calcium silicate minerals: natural and synthetic tobermorite.

    PubMed

    Monasterio, Manuel; Gaitero, Juan J; Manzano, Hegoi; Dolado, Jorge S; Cerveny, Silvina

    2015-05-01

    Confined water in the slit mesopores of the mineral tobermorite provides an excellent model system for analyzing the dynamic properties of water confined in cement-like materials. In this work, we use broadband dielectric spectroscopy (BDS) to analyze the dynamic of water entrapped in this crystalline material. Two samples, one natural and one synthetic, were analyzed, and despite their similar structure, the motion of confined water in their zeolitic cavity displays considerably different behavior. The water dynamics splits into two different behaviors depending on the chemical nature of the otherwise identical structural environment: water molecules located in areas where the primary building units are SiO4 relax slowly compared to water molecules located in cavities built with both AlO4 and SiO4. Compared to water confined in regular porous systems, water restricted in tobermorite is slower, indicating that the mesopore structure induces high disorder in the water structure. A comparison with water confined in the C-S-H gel is also discussed in this work. The strong dynamical changes in water due to the presence of aluminum might have important implications in the chemical transport of ions within hydrated calcium silicates, a process that governs the leaching and chemical degradation of cement.

  17. The nature of Earth's building materials as revealed by calcium isotopes

    NASA Astrophysics Data System (ADS)

    Valdes, M. C.; Moreira, M. A.; Boyet, M.; Foriel, J.; Moynier, F.

    2013-12-01

    Isotopic ratios have traditionally been used as tracers of the genetic link between meteorites and the Earth. Of the major primitive meteorite groups, enstatite chondrites (EC) are the most similar to Earth with regard to the isotopic composition of most elements (e.g. Javoy et al., 2010). In contrast to many isotope systems, calcium (Ca) exhibits significant mass-dependent variation between Earth and EC, though the magnitude of the difference is debated. Simon and DePaolo (2010) find a 0.4‰ difference between EC and Earth while Huang and Jacobsen (2012) find EC and Earth to be identical within error bars. Here we have developed a new method to resolve the difference in Ca isotopic composition at the 0.1 permil level. The method has been applied to a range of terrestrial and meteoritic samples, including seven EC, 12 carbonaceous chondrites (CC) representing most subgroups (CI, CV, CO, CM, CB, CR), six ordinary chondrites (OC), five lunar basalts, and six terrestrial rock standards. In addition, we measured 13 ocean island basalt (OIB) samples from a series of compositional ranges (EM1, EM2, HIMU) to better estimate the Ca isotopic composition of the mantle. Calcium was purified by a combination of Eichrom DGA and Sr-Spec resins and the isotope ratios 42Ca/44Ca and 43Ca/44Ca were measured by standard bracketing normalized to NIST SRM 915b in medium or high resolution on a Thermo-Fisher Neptune Plus MC-ICP-MS at Washington University in St. Louis. All data reported below follow a mass-dependent fractionation law with δ42/44Ca ≈ 2 × δ43/44Ca. As is convention in Ca isotope studies performed on TIMS, we present the data as δ44/40Ca (calculated as -2 × δ42/44Ca) and renormalize to SRM 915a. We find the δ44/40Ca value of NIST SRM 915b relative to SRM 915a to be 0.69 × 0.01 (2se), which is in excellent agreement with previously reported values. Our results show that geostandards are in good agreement with previous data (e.g. δ44CaBHVO-1 = 0.88 × 0.02‰, 2

  18. Comparing the Calcium Binding Abilities of Two Soybean Calmodulins: Towards Understanding the Divergent Nature of Plant Calmodulins[W

    PubMed Central

    Gifford, Jessica L.; Jamshidiha, Mostafa; Mo, Jeffrey; Ishida, Hiroaki; Vogel, Hans J.

    2013-01-01

    The discovery that plants contain multiple calmodulin (CaM) isoforms of variable sequence identity to animal CaM suggested an additional level of sophistication in the intracellular role of calcium regulation in plants. Past research has focused on the ability of conserved or divergent plant CaM isoforms to activate both mammalian and plant protein targets. At present, however, not much is known about how these isoforms respond to the signal of an increased cytosolic calcium concentration. Here, using isothermal titration calorimetry and NMR spectroscopy, we investigated the calcium binding properties of a conserved (CaM1) and a divergent (CaM4) CaM isoform from soybean (Glycine max). Both isoforms bind calcium with a semisequential pathway that favors the calcium binding EF-hands of the C-terminal lobe over those of the N-terminal lobe. From the measured dissociation constants, CaM4 binds calcium with a threefold greater affinity than CaM1 (Kd,Ca,mean of 5.0 versus 14.9 μM) but has a significantly reduced selectivity against the chemically similar magnesium cation that binds preferentially to EF-hand I of both isoforms. The implications of a potential magnesium/calcium competition on the activation of CaM1 and CaM4 are discussed in context with their ability to respond to stimulus-specific calcium signatures and their known physiological roles. PMID:24254124

  19. Rapidly assessing changes in bone mineral balance using natural stable calcium isotopes.

    PubMed

    Morgan, Jennifer L L; Skulan, Joseph L; Gordon, Gwyneth W; Romaniello, Stephen J; Smith, Scott M; Anbar, Ariel D

    2012-06-19

    The ability to rapidly detect changes in bone mineral balance (BMB) would be of great value in the early diagnosis and evaluation of therapies for metabolic bone diseases such as osteoporosis and some cancers. However, measurements of BMB are hampered by difficulties with using biochemical markers to quantify the relative rates of bone resorption and formation and the need to wait months to years for altered BMB to produce changes in bone mineral density large enough to resolve by X-ray densitometry. We show here that, in humans, the natural abundances of Ca isotopes in urine change rapidly in response to changes in BMB. In a bed rest experiment, use of high-precision isotope ratio MS allowed the onset of bone loss to be detected in Ca isotope data after about 1 wk, long before bone mineral density has changed enough to be detectable with densitometry. The physiological basis of the relationship between Ca isotopes and BMB is sufficiently understood to allow quantitative translation of changes in Ca isotope abundances to changes in bone mineral density using a simple model. The rate of change of bone mineral density inferred from Ca isotopes is consistent with the rate observed by densitometry in long-term bed rest studies. Ca isotopic analysis provides a powerful way to monitor bone loss, potentially making it possible to diagnose metabolic bone disease and track the impact of treatments more effectively than is currently possible.

  20. Rapidly assessing changes in bone mineral balance using natural stable calcium isotopes

    NASA Astrophysics Data System (ADS)

    Morgan, Jennifer L. L.; Skulan, Joseph L.; Gordon, Gwyneth W.; Romaniello, Stephen J.; Smith, Scott M.; Anbar, Ariel D.

    2012-06-01

    The ability to rapidly detect changes in bone mineral balance (BMB) would be of great value in the early diagnosis and evaluation of therapies for metabolic bone diseases such as osteoporosis and some cancers. However, measurements of BMB are hampered by difficulties with using biochemical markers to quantify the relative rates of bone resorption and formation and the need to wait months to years for altered BMB to produce changes in bone mineral density large enough to resolve by X-ray densitometry. We show here that, in humans, the natural abundances of Ca isotopes in urine change rapidly in response to changes in BMB. In a bed rest experiment, use of high-precision isotope ratio MS allowed the onset of bone loss to be detected in Ca isotope data after about 1 wk, long before bone mineral density has changed enough to be detectable with densitometry. The physiological basis of the relationship between Ca isotopes and BMB is sufficiently understood to allow quantitative translation of changes in Ca isotope abundances to changes in bone mineral density using a simple model. The rate of change of bone mineral density inferred from Ca isotopes is consistent with the rate observed by densitometry in long-term bed rest studies. Ca isotopic analysis provides a powerful way to monitor bone loss, potentially making it possible to diagnose metabolic bone disease and track the impact of treatments more effectively than is currently possible.

  1. Dioxins, furans, biphenyls, arsenic, thorium and uranium in natural and anthropogenic sources of phosphorus and calcium used in agriculture.

    PubMed

    Avelar, A C; Ferreira, W M; Pemberthy, D; Abad, E; Amaral, M A

    2016-05-01

    The aim of this study was to assess the presence of dioxins, furans and biphenyls, and the inorganic contaminants such as arsenic (As), thorium (Th) and uranium (U) in three main products used in Agriculture in Brazil: feed grade dicalcium phosphate, calcined bovine bone meal and calcitic limestone. The first two are anthropogenic sources of phosphorus and calcium, while calcitic limestone is a natural unprocessed mineral. Regarding to dioxin-like substances, all samples analyzed exhibited dioxins (PCDD) and furans (PCDF) and dioxin-like polychlorinated biphenyls (dl-PCBs) concentrations below limit of detection (LOD). In general, achieved is in accordance with regulation in Brazil where is established a maximum limit in limestone used in the citric pulp production (0.50pg WHO-TEQ g(-1)). In addition, reported data revealed very low levels for limestone in comparison with similar materials reported by European legislation. As result for toxic metals, achieved data were obtained using Instrumental Neutron Activation Analysis (INAA). On one hand, limestone sample exhibits the largest arsenic concentration. On another hand, dicalcium phosphate exhibited the largest uranium concentration, which represents a standard in animal nutrition. Therefore, it is phosphorus source in the animal feed industry can be a goal of concern in the feed field. PMID:26901743

  2. Dioxins, furans, biphenyls, arsenic, thorium and uranium in natural and anthropogenic sources of phosphorus and calcium used in agriculture.

    PubMed

    Avelar, A C; Ferreira, W M; Pemberthy, D; Abad, E; Amaral, M A

    2016-05-01

    The aim of this study was to assess the presence of dioxins, furans and biphenyls, and the inorganic contaminants such as arsenic (As), thorium (Th) and uranium (U) in three main products used in Agriculture in Brazil: feed grade dicalcium phosphate, calcined bovine bone meal and calcitic limestone. The first two are anthropogenic sources of phosphorus and calcium, while calcitic limestone is a natural unprocessed mineral. Regarding to dioxin-like substances, all samples analyzed exhibited dioxins (PCDD) and furans (PCDF) and dioxin-like polychlorinated biphenyls (dl-PCBs) concentrations below limit of detection (LOD). In general, achieved is in accordance with regulation in Brazil where is established a maximum limit in limestone used in the citric pulp production (0.50pg WHO-TEQ g(-1)). In addition, reported data revealed very low levels for limestone in comparison with similar materials reported by European legislation. As result for toxic metals, achieved data were obtained using Instrumental Neutron Activation Analysis (INAA). On one hand, limestone sample exhibits the largest arsenic concentration. On another hand, dicalcium phosphate exhibited the largest uranium concentration, which represents a standard in animal nutrition. Therefore, it is phosphorus source in the animal feed industry can be a goal of concern in the feed field.

  3. Direct activation of the mitochondrial calcium uniporter by natural plant flavonoids

    PubMed Central

    2004-01-01

    During cell activation, mitochondria play an important role in Ca2+ homoeostasis due to the presence of a fast and specific Ca2+ channel in its inner membrane, the mitochondrial Ca2+ uniporter. This channel allows mitochondria to buffer local cytosolic [Ca2+] changes and controls the intramitochondrial Ca2+ levels, thus modulating a variety of phenomena from respiratory rate to apoptosis. We have described recently that SB202190, an inhibitor of p38 MAPK (mitogen-activated protein kinase), strongly activated the uniporter. We show in the present study that a series of natural plant flavonoids, widely distributed in foods, produced also a strong stimulation of the mitochondrial Ca2+ uniporter. This effect was of the same magnitude as that induced by SB202190 (an approx. 20-fold increase in the mitochondrial Ca2+ uptake rate), developed without measurable delay and was rapidly reversible. In intact cells, the mitochondrial Ca2+ peak induced by histamine was also largely increased by the flavonoids. Stimulation of the uniporter by either flavonoids or SB202190 did not require ATP, suggesting a direct effect on the uniporter or an associated protein which is not mediated by protein phosphorylation. The most active compound, kaempferol, increased the rate of mitochondrial Ca2+ uptake by 85±15% (mean±S.E.M., n=4) and the histamine-induced mitochondrial Ca2+ peak by 139±19% (mean±S.E.M., n=5) at a concentration of 1 μM. Given that flavonoids can reach this concentration range in plasma after ingestion of flavonoid-rich food, these compounds could be modulating the uniporter under physiological conditions. PMID:15324303

  4. Fluoride in diet

    MedlinePlus

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

  5. Serum fluoride and sialic acid levels in osteosarcoma.

    PubMed

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

    2011-12-01

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

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

    PubMed

    ten Cate, J M

    1999-12-01

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

  7. Fluorides in the new millennium.

    PubMed

    Padilla, O; Davis, M J

    2001-02-01

    Water fluoridation is known to be the most successful public health measure of the 20th century. More than half a century later, we are still reaping the benefits of fluoridation. We now know that the most important mechanism of fluoride action occurs through daily low-dose exposures. The battle between demineralization and remineralization occurs constantly, and fluoride shifts the balance to the latter. This dynamic, daily process far supersedes the pre-eruptive fluoride incorporation in importance. Fluoride, however, is now available in a variety of very different forms, useful in waging the war on caries. Nevertheless, opponents of this therapeutic agent maintain that its widespread use should be curtailed. Although the benefits of fluoride can no longer be disputed, fluoride supplementation must be supported and approached with consideration of total fluoride exposure. PMID:11280144

  8. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium alginate. 184.1187 Section 184.1187 Food... GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Calcium alginate is prepared...

  9. Fluoride-treated bio-resorbable synthetic nonceramic [corrected] hydroxyapatite promotes proliferation and differentiation of human osteoblastic MG-63 cells.

    PubMed

    Ohno, Motofumi; Kimoto, Kazunari; Toyoda, Toshihisa; Kawata, Kazushige; Arakawa, Hirohisa

    2013-04-01

    When resorbable hydroxyapatite (HA) granules, which are used as a bone supplement material, were treated in neutral 4% sodium fluoride (NaF) solution, formation of a reactant resembling calcium fluoride was observed on the surface of the granules. Immediate and slow release of fluoride from fluoridated HA (HA+F) granules was observed after immersion in culture fluid, and the concentration increased over time to 1.25 ± 0.05 ppm F at 0.5 hours, 1.57 ± 0.12 ppm F at 24 hours, and 1.73 ± 0.15 ppm F at 48 hours. On invasion assay, migration of human osteoblast-like MG-63 cells exposed to the released fluoride was confirmed in comparison to the cells incubated with a nonfluoridated control sample (P < .01). In addition, fluoride added to the medium increased MG-63 cell proliferation in a manner dependent on fluoride concentrations up to 2.0 ppm (P < .05). At 5.0 ppm, however, fluoride significantly inhibited cell proliferation (P < .005). Activity of the osteogenic differentiation marker, alkaline phosphatase (ALP), also increased with fluoride after exposure for 1 week, increasing significantly at 1.0 ppm (P < .05). The promotion of MG-63 cell migration and proliferation, as well as increased ALP activity, suggested that fluoride released from the surface of resorbable HA granules, which were fluoridated by prior treatment with neutral 4% NaF solution, can provide a superb method to supply fluoride and promote osteogenic cell differentiation.

  10. Quality of our groundwater resources: arsenic and fluoride

    USGS Publications Warehouse

    Nordstrom, D. Kirk

    2011-01-01

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

  11. Pilot-scale fluoride-containing wastewater treatment by the ballasted flocculation process.

    PubMed

    Wang, Bin-Yuan; Chen, Zhong-Lin; Zhu, Jia; Shen, Ji-Min; Han, Ying

    2013-01-01

    A pilot-scale ballasted flocculation system was used to remove fluoride from one type of industrial wastewater. The system included the formation of calcium fluoride (CaF2) using calcium hydroxide followed by coagulation sedimentation. Calcium fluoride was recycled as nuclei for enhancing CaF2 precipitation and as a ballasting agent for improving fluoride removal and flocculation efficiency. Factors affecting fluoride and turbidity removal efficiencies, including pH in the CaF2-reacting tank and coagulation-mixing tank, sludge recycling ratio, and dosages of FeCl3 and polyacrylamide (PAM), were investigated in the pilot-scale system. The recycled CaF2 precipitates improved CaF2 formation kinetics, enhanced fluoride removal and flocculation performance. Under the optimized condition, the ballast flocculation process reduced fluoride concentration from 288.9 to 10.67 mg/L and the turbidity from 129.6 NTU to below 2.5 NTU. PMID:23823549

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

    PubMed

    Chan, J T; Koh, S H

    1996-01-01

    The fluoride contents of infusions prepared from 44 different brands and types of teas were measured. Fluoride concentrations ranged from 0.34 to 3.71 ppm (mean = 1.50 ppm) in caffeinated tea infusions, 0.02-0.14 ppm (mean = 0.05 ppm) in herbal tea infusions, and 1.01-5.20 ppm (mean = 3.19) in decaffeinated tea infusions. This is the first report of the fluoride content of decaffeinated teas. The mean fluoride content of decaffeinated tea infusions is significantly (p < 0.01) higher than the corresponding caffeinated tea. The use of mineral water containing a naturally high fluoride level during the process of decaffeination is the most likely explanation of the above observation.

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

    PubMed

    Chan, J T; Koh, S H

    1996-01-01

    The fluoride contents of infusions prepared from 44 different brands and types of teas were measured. Fluoride concentrations ranged from 0.34 to 3.71 ppm (mean = 1.50 ppm) in caffeinated tea infusions, 0.02-0.14 ppm (mean = 0.05 ppm) in herbal tea infusions, and 1.01-5.20 ppm (mean = 3.19) in decaffeinated tea infusions. This is the first report of the fluoride content of decaffeinated teas. The mean fluoride content of decaffeinated tea infusions is significantly (p < 0.01) higher than the corresponding caffeinated tea. The use of mineral water containing a naturally high fluoride level during the process of decaffeination is the most likely explanation of the above observation. PMID:8850589

  14. Phosphate reduction in a hydroxyapatite fluoride removal system

    NASA Astrophysics Data System (ADS)

    Egner, A.

    2012-12-01

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

  15. Effect of Oestrogen on Altering the Serum and Urinary Levels of Calcium, Phosphate and Magnesium in Hysterectomised Women Compared to Natural Menopausal South Indian Women: A Case Control Study.

    PubMed

    Sonu, Yeldose; Avinash, S S; Sreekantha; Arun Kumar, K; Malathi, M; Shivashankara, A R

    2016-07-01

    Given the paucity of studies conducted to know the effect of suddenness and earlier onset of endocrinological changes associated with hysterectomy, on the serum and urinary levels of calcium, magnesium and phosphate the present study was conducted to compare the levels of calcium, magnesium and phosphate in serum and urine of hysterectomised and natural menopausal south Indian women. This is a cross-sectional observational study. The study included three groups of 30 healthy premenopausal, 30 early surgical menopausal and 30 natural post menopausal women. Women suffering from any endocrine disease were excluded. Analysis was performed in serum and urine sample. The levels of calcium, magnesium and phosphate in serum and calcium/creatinine, magnesium/creatinine and phosphate/creatinine ratio were estimated in urine by spectrophotometric method. Hysterectomised women (serum calcium: 8.7 ± 0.09 mg/dl; urine calcium/creatinine: 0.16 ± 0.02) have significantly low serum calcium (p < 0.001) and high urinary calcium/creatinine (p = 0.002) ratio and post menopausal women (serum magnesium: 2.1 ± 0.03; serum phosphate: 4.4 ± 0.16; urinary calcium/creatinine: 0.17 ± 0.02; urinary magnesium/creatinine: 0.09 ± 0.01) have significantly high serum magnesium (p = 0.016), serum phosphate (p = 0.043) and high urinary calcium/creatinine (p = 0.002), magnesium/creatinine ratio (p = 0.025) compared to healthy pre menopausal women. Post menopausal women (serum calcium: 9.1 ± 0.08) have significantly high serum calcium and phosphate compared to hysterectomised women (serum phosphate: 3.93 ± 0.11). Hysterectomised women have significantly low serum calcium, oestrogen and high urinary calcium/creatinine ratio compared to healthy premenopausal women and low serum calcium and low serum phosphate compared to natural postmenopausal women. Natural postmenopausal women had low serum oestrogen and high serum magnesium, serum phosphate, urinary calcium

  16. Private Well Water and Fluoride

    MedlinePlus

    ... from my well has less than the recommended level of fluoride for preventing tooth decay? The recommended ... if the water from my well has fluoride levels that are higher than the recommended level for ...

  17. Aqueous geochemistry of fluoride enriched groundwater in arid part of Western India.

    PubMed

    Singh, Chander Kumar; Mukherjee, Saumitra

    2015-02-01

    Fluoride-enriched water has become a major public health issue in India. The present study tries to evaluate the geochemical mechanism of fluoride enrichment in groundwater of western India. Total 100 groundwater samples were collected for the study spreading across the entire study area. The results of the analyzed parameters formed the attribute database for geographical information system (GIS) analysis and final output maps. A preliminary field survey was conducted and fluoride testing was done using Hach make field kits. The fluoride concentration ranges from 0.08 to 6.6 mg/L (mean 2.4 mg/L), with 63 % of the samples containing fluoride concentrations that exceed the World Health Organization (WHO) drinking water guideline value of 1.5 mg/L and 85 % samples exceeding the Bureau of Indian Standards (BIS) guidelines of 1 mg/L. The study also reveals high concentration of nitrate that is found to be above WHO standrads. The dominant geochemical facies present in water are Na-Cl-HCO3 (26 samples), Na-Ca-Cl-HCO3 (20 samples), Na-Cl (14 samples), and Na-Ca-Mg-Cl-HCO3 (11 samples); however, sodium and bicarbonate being the major component in all the water types of 100 samples, which in fact has a tendency to increase fluoride concentration in water by dissolving fluoride from fluorite. The thermodynamic considerations between the activities of calcium, fluoride, and bicarbonate suggest that fluoride concentration is being governed by activity of calcium ion. X-ray diffraction analysis of sediments reveals calcite and fluorite are the main solubility-control minerals controlling the aqueous geochemistry of high fluoride groundwater. The results indicate that the fluoride concentration in groundwater is mainly governed by geochemical composition of rocks, such as metamorphic granites and sedimentary rocks, alkaline hydrogeological environment, climatic conditions, high temperature and lesser rainfall, and geochemical processes such as weathering, evaporation

  18. Potential exposure and risk of fluoride intakes from tea drinks produced in Taiwan.

    PubMed

    Lung, Shih-Chun Candice; Cheng, Hui-Wen; Fu, Chi Betsy

    2008-03-01

    Tea is the second most commonly consumed drink in the world. Excess fluoride intakes from tea drinks may cause health effects. This work assesses infusible fluoride levels in popular tea sold in Taiwan and evaluates potential exposure factors. Lungjing, pouchong, tienguanyin, oolong, pureh, and black tea specimens were purchased from different counties in Taiwan. Fluoride levels were evaluated in one complete cycle of tea making as well as at different calcium carbonate contents in water, with glass or porcelain teapots, and with/without adding sugar. Oolong tea leaves in each manufacturing step were also analyzed for infusible fluoride. Potential fluoride intakes and risks are estimated based on a national survey. Among six kinds of tea, black tea had the highest fluoride concentrations (8.64+/-2.96 mg/l), whereas pureh (1.97+/-2.70 mg/l) had the lowest levels. Higher percentages of infusible fluoride can be rinsed away from tea leaves curved lengthways compared to those curved end-to-end in the first 2.5 min. The use of glass or porcelain teapots and calcium carbonate content (up to 400 mg/l) in water would not affect infusible fluoride levels, whereas adding sugar increased the infusible fluoride in the first few minutes. In addition, it was found that the critical step during the manufacturing process affecting the percentage of infusible fluoride was ball rolling rather than fermentation. Furthermore, intakes of high amounts (> or =5 l/week) of certain tea may result in excess risks of dental or skeletal fluorosis. Tea lovers could be exposed to excess fluoride and may be at risk of fluorosis.

  19. Aqueous geochemistry of fluoride enriched groundwater in arid part of Western India.

    PubMed

    Singh, Chander Kumar; Mukherjee, Saumitra

    2015-02-01

    Fluoride-enriched water has become a major public health issue in India. The present study tries to evaluate the geochemical mechanism of fluoride enrichment in groundwater of western India. Total 100 groundwater samples were collected for the study spreading across the entire study area. The results of the analyzed parameters formed the attribute database for geographical information system (GIS) analysis and final output maps. A preliminary field survey was conducted and fluoride testing was done using Hach make field kits. The fluoride concentration ranges from 0.08 to 6.6 mg/L (mean 2.4 mg/L), with 63 % of the samples containing fluoride concentrations that exceed the World Health Organization (WHO) drinking water guideline value of 1.5 mg/L and 85 % samples exceeding the Bureau of Indian Standards (BIS) guidelines of 1 mg/L. The study also reveals high concentration of nitrate that is found to be above WHO standrads. The dominant geochemical facies present in water are Na-Cl-HCO3 (26 samples), Na-Ca-Cl-HCO3 (20 samples), Na-Cl (14 samples), and Na-Ca-Mg-Cl-HCO3 (11 samples); however, sodium and bicarbonate being the major component in all the water types of 100 samples, which in fact has a tendency to increase fluoride concentration in water by dissolving fluoride from fluorite. The thermodynamic considerations between the activities of calcium, fluoride, and bicarbonate suggest that fluoride concentration is being governed by activity of calcium ion. X-ray diffraction analysis of sediments reveals calcite and fluorite are the main solubility-control minerals controlling the aqueous geochemistry of high fluoride groundwater. The results indicate that the fluoride concentration in groundwater is mainly governed by geochemical composition of rocks, such as metamorphic granites and sedimentary rocks, alkaline hydrogeological environment, climatic conditions, high temperature and lesser rainfall, and geochemical processes such as weathering, evaporation

  20. MOLTEN FLUORIDE NUCLEAR REACTOR FUEL

    DOEpatents

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

    1960-01-01

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

  1. Calcium Carbonate

    MedlinePlus

    Calcium carbonate is a dietary supplement used when the amount of calcium taken in the diet is not ... for healthy bones, muscles, nervous system, and heart. Calcium carbonate also is used as an antacid to relieve ...

  2. Calcium - urine

    MedlinePlus

    High levels of urine calcium (above 300 mg/day) may be due to: Chronic kidney disease High vitamin D levels Leaking of calcium from the kidneys into the urine, which causes calcium kidney stones Sarcoidosis Taking ...

  3. Effect of trimetaphosphate and fluoride association on hydroxyapatite dissolution and precipitation in vitro.

    PubMed

    Delbem, Alberto Carlos Botazzo; Souza, José Antonio Santos; Zaze, Ana Carolina Soares Fraga; Takeshita, Eliana Mitsue; Sassaki, Kikue Takebayashi; Moraes, João Carlos Silos

    2014-01-01

    The present study analyzed the action of sodium trimetaphosphate (TMP) and/or fluoride on hydroxyapatite. Hydroxyapatite powder was suspended in different solutions: deionized water, 500 µg F/mL, 1,100 µg F/mL, 1%TMP, 3%TMP, 500 µg F/mL plus 1%TMP and 500 µg F/mL plus 3%TMP. The pH value of the solutions was reduced to 4.0 and after 30 min, raised to 7.0 (three times). After pH-cycling, the samples were analyzed by X-ray diffraction and infrared spectroscopy. The concentrations of calcium fluoride, fluoride, calcium and phosphorus were also determined. Adding 1% or 3% TMP to the solution containing 500 µg F/mL produced a higher quantity of calcium fluoride compared to samples prepared in a 1,100 µg F/mL solution. Regarding the calcium concentration, samples prepared in solutions of 1,100 µg F/mL and 500 µg F/mL plus TMP were statistically similar and showed higher values. Using solutions of 1,100 µg F/mL and 500 µg F/mL plus TMP resulted in a calcium/phosphorus ratio close to that of hydroxyapatite. It is concluded that the association of TMP and fluoride favored the precipitation of a more stable hydroxyapatite. PMID:25590192

  4. Fluoride inhibition of the hydro-osmotic response of the toad urinary bladder to antidiuretic hormone.

    PubMed

    Yorio, T; Sinclair, R; Henry, S

    1981-11-01

    The hydro-osmotic response of the toad bladder to antidiuretic hormone and cyclic AMP was inhibited by the methoxyflurane metabolite, fluoride. The osmotic transfer of water in the absence of hormone was unaffected by fluoride as was the hydroosmotic response due to hypertonicity of the serosal bathing media. Osmotic water movements across N-ethylmaleimide-"fixed" vasopressin or cyclic AMP-stimulated bladders were likewise unchanged by fluoride, suggesting that fluoride is exerting an action subsequent to the endogenous formation of cyclic AMP but before the final effector mechanism. Fluoride increased intracellular cyclic AMP concentrations even in the presence of added hormone. Fluoride suppressed calmodulin activity and prevented its activation of phosphodiesterase. Fluoride had no effect on oxygen consumption of toad urinary bladder cells but reduced lactate formation and anerobic metabolism. This decrease in the glycolytic energy source did not contribute to the inhibition of the hormonal response since 2-deoxyglucose was without effect on hormonal mediated osmotic-water flow. It is postulated that the fluoride-induced polyuria after methoxyflurane anesthesia may be due in part to the ability of fluoride to interfere with calcium and calmodulin-initiated processes (other than phosphodiesterase activity) that may occur in the stimulus-reabsorption coupling response of antidiuretic hormone.

  5. Fluoride removal from groundwater by limestone treatment in presence of phosphoric acid.

    PubMed

    Gogoi, Sweety; Nath, Suresh K; Bordoloi, Shreemoyee; Dutta, Robin K

    2015-04-01

    Fluoride removal from groundwater has been studied by addition of dilute phosphoric acid (PA) to the influent water before limestone treatment through laboratory plug-flow column experiments and bench-scale plug-flow pilot tests. In this PA-enhanced limestone defluoridation (PAELD) technique, fluoride is removed from 0.526 mM to 0.50-52.60 μM in 3 h with near neutral final pH. The presence of PA increases the fluoride removal capacity of limestone to 1.10 mg/g compared to 0.39 mg/g reported in its absence. The changes in fluoride removal with variation in initial PA concentration, initial fluoride concentration and the final pH have been found to be statistically significant with p < 0.05. The estimated recurring cost is US$ ≈0.58/m(3) water. Simple scrubbing and rinsing is a preferable method for regeneration of limestone as it is almost equally effective with lime or NaOH. Sorption of fluoride by calcium phosphates produced in situ in the reactor is the dominant mechanism of fluoride removal in the PAELD. Precipitation of CaF2 and sorption of fluoride by the limestone also contribute to the fluoride removal. High efficiency, capacity, safety, environment-friendliness, low cost and simplicity of operation make the PAELD a potential technique for rural application. PMID:25621387

  6. Effects of Life-long Fluoride Intake on Bone Measures of Adolescents

    PubMed Central

    Levy, S.M.; Warren, J.J.; Phipps, K.; Letuchy, E.; Broffitt, B.; Eichenberger-Gilmore, J.; Burns, T.L.; Kavand, G.; Janz, K.F.; Torner, J.C.; Pauley, C.A.

    2014-01-01

    Controversy persists concerning the impact of community water fluoridation on bone health in adults, and few studies have assessed relationships with bone at younger ages. Ecological studies of fluoride’s effects showed some increase in bone mineral density of adolescents and young adults in areas with fluoridated water compared with non-fluoridated areas. However, none had individual fluoride exposure measures. To avoid ecological fallacy and reduce bias, we assessed associations of average daily fluoride intake from birth to age 15 yr for Iowa Bone Development Study cohort members with age 15 yr dual-energy x-ray absorptiometry (DXA) bone outcomes (whole body, lumbar spine, and hip), controlling for known determinants (including daily calcium intake, average daily time spent in moderate-to-vigorous intensity physical activity, and physical maturity). Mean (SD) daily fluoride intake was 0.66 mg (0.24) for females and 0.78 mg (0.30) for males. We found no significant relationships between daily fluoride intake and adolescents’ bone measures in adjusted models (for 183 females, all p values ≥ .10 and all partial R2 ≤ 0.02; for 175 males, all p values ≥ .34 and all partial R2 ≤ 0.01). The findings suggest that fluoride exposures at the typical levels for most US adolescents in fluoridated areas do not have significant effects on bone mineral measures. PMID:24470542

  7. Fluoride removal from groundwater by limestone treatment in presence of phosphoric acid.

    PubMed

    Gogoi, Sweety; Nath, Suresh K; Bordoloi, Shreemoyee; Dutta, Robin K

    2015-04-01

    Fluoride removal from groundwater has been studied by addition of dilute phosphoric acid (PA) to the influent water before limestone treatment through laboratory plug-flow column experiments and bench-scale plug-flow pilot tests. In this PA-enhanced limestone defluoridation (PAELD) technique, fluoride is removed from 0.526 mM to 0.50-52.60 μM in 3 h with near neutral final pH. The presence of PA increases the fluoride removal capacity of limestone to 1.10 mg/g compared to 0.39 mg/g reported in its absence. The changes in fluoride removal with variation in initial PA concentration, initial fluoride concentration and the final pH have been found to be statistically significant with p < 0.05. The estimated recurring cost is US$ ≈0.58/m(3) water. Simple scrubbing and rinsing is a preferable method for regeneration of limestone as it is almost equally effective with lime or NaOH. Sorption of fluoride by calcium phosphates produced in situ in the reactor is the dominant mechanism of fluoride removal in the PAELD. Precipitation of CaF2 and sorption of fluoride by the limestone also contribute to the fluoride removal. High efficiency, capacity, safety, environment-friendliness, low cost and simplicity of operation make the PAELD a potential technique for rural application.

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

    PubMed

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

    2016-02-01

    Excessive fluoride in natural water ecosystem has the potential to detrimentally affect thyroid endocrine system, but little is known of such effects or underlying mechanisms in fish. In the present study, we evaluated the effects of fluoride on growth performance, thyroid histopathology, thyroid hormone levels, and gene expressions in the HPT axis in male zebrafish (Danio rerio) exposed to different determined concentrations of 0.1, 0.9, 2.0 and 4.1 M of fluoride to investigate the effects of fluoride on thyroid endocrine system and the potential toxic mechanisms caused by fluoride. The results indicated that the growth of the male zebrafish used in the experiments was significantly inhibited, the thyroid microtrastructure was changed, and the levels of T3 and T4 were disturbed in fluoride-exposed male fish. In addition, the expressional profiles of genes in HPT axis displayed alteration. The expressions of all studied genes were significantly increased in all fluoride-exposed male fish after exposure for 45 days. The transcriptional levels of corticotrophin-releasing hormone (CRH), thyroid-stimulating hormone (TSH), thyroglobulin (TG), sodium iodide symporter (NIS), iodothyronine I (DIO1), and thyroid hormone receptor alpha (TRα) were also elevated in all fluoride-exposed male fish after 90 days of exposure, while the inconsistent expressions were found in the mRNA of iodothyronineⅡ (DIO2), UDP glucuronosyltransferase 1 family a, b (UGT1ab), transthyretin (TTR), and thyroid hormone receptor beta (TRβ). These results demonstrated that fluoride could notably inhibit the growth of zebrafish, and significantly affect thyroid endocrine system by changing the microtrastructure of thyroid, altering thyroid hormone levels and endocrine-related gene expressions in male zebrafish. All above indicated that fluoride could pose a great threat to thyroid endocrine system, thus detrimentally affected the normal function of thyroid of male zebrafish. PMID:26748264

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

    PubMed

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

    2016-02-01

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

  10. Mode of action of fluoride: application of new techniques and test methods to the examination of the mechanism of action of topical fluoride.

    PubMed

    White, D J; Nelson, D G; Faller, R V

    1994-07-01

    Modern techniques in dental research continue to assist in the study of the mode of (anticaries) action of topical fluorides. The Plaque Glycolysis and Regrowth Model (PGRM) facilitates the standardized assessments of antimicrobial effects on plaque following use of test formulations in vivo without complications arising from coincident mineral reactivity. In vivo plaque glycolysis testing demonstrates that topically applied fluoride, at conventional levels found in dentifrices, has only modest effects on the metabolic (acid-producing) activity of dental plaque. Any 'plaque' contribution to fluoride efficacy must come from more subtle effects on plaque acidogenicity than those measured in PGRM. The 19-FMAS NMR (Magic Angle Spinning Nuclear Magnetic Resonance) technique provides unambiguous measures of the reaction products of F-enamel interactions. Studies have revealed a new 'reaction product' of fluoride-enamel interactions--designated as Non-Specifically-Adsorbed Fluoride, NSAF. This species, along with FAP (fluoroapatite), FHAP (fluorohydroxyapatite), and CaF2 (calcium fluoride), contributes to the remineralization/demineralization benefits of fluoride. pH cycling and in situ denture chip studies permit quantitative assessments to be made of the relative benefits of fluoride in promoting remineralization and in inhibiting demineralization. Results from pH cycling/in situ experiments are strongly supportive of Koulourides' 'Acquired Acid Resistance' concept, describing fluoride's decay-preventive effects. The continued application of new analytical/physical techniques and testing regimens to the study of fluoride anticaries mechanisms may lead to the development of improved fluoride agents/treatment modalities for the prevention of dental caries.

  11. Direct measurements of stratospheric fluoride

    NASA Technical Reports Server (NTRS)

    Mroz, E. J.; Lazrus, A. L.; Bonelli, J. E.

    1977-01-01

    Stratospheric fluoride mass mixing ratios were measured by passing stratospheric air through filters half of which is impregnated in a base. Measurements of stratospheric fluoride were obtained at altitudes from 15 to 40 km at latitude 30-33 N and longitude 95-105 W at different months of the year. The significant amount of fluoride collected on the base-impregnated portion of the filters suggests that fluoride is present in the stratosphere as an acid gas. The mixing ratios decrease markedly at altitudes less than 20-25 km, suggesting the troposphere as the major sink for stratospheric fluoride.

  12. Fluorine (soluble fluoride)

    Integrated Risk Information System (IRIS)

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

  13. Other Fluoride Products

    MedlinePlus

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

  14. Ferrimyoglobin-Fluoride.

    ERIC Educational Resources Information Center

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

    1990-01-01

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

  15. Sensitivity of two biomarkers for biomonitoring exposure to fluoride in children and women: A study in a volcanic area.

    PubMed

    Linhares, Diana Paula Silva; Garcia, Patrícia Ventura; Amaral, Leslie; Ferreira, Teresa; Cury, Jaime A; Vieira, Waldomiro; Rodrigues, Armindo Dos Santos

    2016-07-01

    The natural enrichment of water with fluoride is related to natural sources such as volcanic activity, with it being documented that fluorosis, an endemic and widespread disease in volcanic areas, is associated to the ingestion of high levels of fluoride through water. Thus, in this study, we aimed to define the fluoride concentration in drinking waters of volcanic origin and compare the sensitivity of urine and nail clippings as biomarkers for fluoride exposure in adults and children. Samples of drinking water from four villages in São Miguel Island (Azores) were used and the fluoride concentration was determined, as well the fluoride content in urine and toenails clippings from 66 children and 63 adults from these villages. A validated diet questionnaire, assessing sources of fluoride, was recorded for each participant. The fluoride determination in urine and nail clipping samples was made using a fluoride-specific electrode. A positive correlation was found between the fluoride daily intake and fluoride content in children urine (rs = 0.475; p < 0.001) and in their nail clippings (rs = 0.475; p < 0.001), while in adult women, the fluoride daily intake correlated positively with fluoride content nail clippings (rs = 0.495, p < 0.001). This reveals that nail clippings are more reliable as biomarkers of chronic exposure to fluoride than urine for populations of different ages (children vs. adults). Furthermore, nail clippings are more suitable than urine fluoride levels to assess long term exposure to fluoride in areas where the exposure to fluoride in drinking water is considered within, or slightly above, the recommended legal values.

  16. Sensitivity of two biomarkers for biomonitoring exposure to fluoride in children and women: A study in a volcanic area.

    PubMed

    Linhares, Diana Paula Silva; Garcia, Patrícia Ventura; Amaral, Leslie; Ferreira, Teresa; Cury, Jaime A; Vieira, Waldomiro; Rodrigues, Armindo Dos Santos

    2016-07-01

    The natural enrichment of water with fluoride is related to natural sources such as volcanic activity, with it being documented that fluorosis, an endemic and widespread disease in volcanic areas, is associated to the ingestion of high levels of fluoride through water. Thus, in this study, we aimed to define the fluoride concentration in drinking waters of volcanic origin and compare the sensitivity of urine and nail clippings as biomarkers for fluoride exposure in adults and children. Samples of drinking water from four villages in São Miguel Island (Azores) were used and the fluoride concentration was determined, as well the fluoride content in urine and toenails clippings from 66 children and 63 adults from these villages. A validated diet questionnaire, assessing sources of fluoride, was recorded for each participant. The fluoride determination in urine and nail clipping samples was made using a fluoride-specific electrode. A positive correlation was found between the fluoride daily intake and fluoride content in children urine (rs = 0.475; p < 0.001) and in their nail clippings (rs = 0.475; p < 0.001), while in adult women, the fluoride daily intake correlated positively with fluoride content nail clippings (rs = 0.495, p < 0.001). This reveals that nail clippings are more reliable as biomarkers of chronic exposure to fluoride than urine for populations of different ages (children vs. adults). Furthermore, nail clippings are more suitable than urine fluoride levels to assess long term exposure to fluoride in areas where the exposure to fluoride in drinking water is considered within, or slightly above, the recommended legal values. PMID:27155929

  17. The Selection and Prevalence of Natural and Fortified Calcium Food Sources in the Diets of Adolescent Girls

    ERIC Educational Resources Information Center

    Rafferty, Karen; Watson, Patrice; Lappe, Joan M.

    2011-01-01

    Objective: To assess the impact of calcium-fortified food and dairy food on selected nutrient intakes in the diets of adolescent girls. Design: Randomized controlled trial, secondary analysis. Setting and Participants: Adolescent girls (n = 149) from a midwestern metropolitan area participated in randomized controlled trials of bone physiology…

  18. Fluoride rinse effect on retention of CaF2 formed on enamel/dentine by fluoride application.

    PubMed

    Falcão, Amanda; Masson, Nadia; Leitão, Tarcísio Jorge; Botelho, Juliana Nunes; Ferreira-Nóbilo, Naiara de Paula; Tabchoury, Cínthia Pereira Machado; Tenuta, Livia Maria Andaló; Cury, Jaime Aparecido

    2016-01-01

    Calcium fluoride-like materials ("CaF2") formed on dental surfaces after professional fluoride application are unstable in the oral environment but can be retained longer with a daily NaF mouthrinse. We tested the effect of twice daily 0.05% NaF rinses on the retention of "CaF2" formed on enamel and dentine after applying acidulated phosphate fluoride (APF). "CaF2" formed on enamel/dentine by APF application significantly decreased after exposure to artificial saliva and the 0.05% NaF rinse was ineffective to avoid this reduction. These findings suggest that the combination of APF and 0.05% NaF is not clinically relevant, either for caries or dental hypersensitivity. PMID:27050937

  19. Effect of fluoride gels on microhardness and surface roughness of bleached enamel.

    PubMed

    China, Ana L P; Souza, Nayara M; Gomes, Yasmin do S B de L; Alexandrino, Larissa D; Silva, Cecy M

    2014-01-01

    The effect of bleaching treatments containing added calcium and combined with neutral or acidic fluoride gels on tooth enamel was investigated in vitro through Knoop microhardness (KHN) and surface roughness (SR) measurements. A total of 60 bovine incisors were tested, including 30 for SR measurements and 30 for KHN measurements. The specimens were divided into 12 groups and subjected to a bleaching agent with hydrogen peroxide 35% (Whiteness HP 35% Maxx, FGM) or hydrogen peroxide 35% with calcium (Whiteness HP 35% Blue Calcium, FGM) and a fluoride treatment flugel acidulated phosphate fluoride (APF) or flugel neutral fluoride (NF). Control specimens were submitted to bleaching treatments without fluoride. Microhardness tests were performed using a Knoop indentor. Roughness measurements were obtained using a roughness analyzer. Measurements were obtained before and after treatment. The specimens were stored in distilled water at 37 °C between treatments. The results were analyzed using descriptive and inferential statistics. Treatments using APF combined with 35% HP caused a decrease in microhardness, while NF combined with HP 35% Ca increased the enamel hardness. Fluoride gels did not alter the SR of the bleached enamel. PMID:25419249

  20. Effects of fluoride on metamorphosis, thyroid and skeletal development in Bufo gargarizans tadpoles.

    PubMed

    Zhao, Hongfeng; Chai, Lihong; Wang, Hongyuan

    2013-09-01

    This study examined the effects of chronic fluoride exposure on metamorphosis, thyroid and skeletal development in tadpoles of Chinese Toad, Bufo gargarizans. The tadpoles were exposed to fluoride concentrations either at 0, 1, 5, 10, or at 50 mg L(-1) from Gosner stage 26 to Gosner stage 42. Body weight, total length and percentage of tadpoles reaching metamorphosis climax were recorded, and thyroid histological examinations were employed. In addition, mRNA expression of both deiodinase type 2 (D2) and deiodinase type 3 (D3) was analyzed by using RT-PCR and skeletal systems were investigated by using double-staining methodology at stage 42. Results showed that total length and body weight were unaffected by fluoride exposure at all concentrations while metamorphosis was strongly inhibited only by 50 mg L(-1) fluoride. Histomorphological measurements showed the percentage of colloid depletion in thyroid gland increased significantly, while the average diameter of follicles was significantly shorter at 50 mg L(-1) concentration. In addition, fluoride at 5 mg L(-1) can stimulate bone mineralization, while fluoride at 50 mg L(-1) can retard deposition of calcium. In conclusion, our study suggests that 50 mg L(-1) fluoride could damage follicular cells in thyroid gland and induce a sharp reduction in thyroid hormone probably through the up-regulation of D3 mRNA expression, and these influences on thyroid system may delay metamorphosis as well as ossification in bone tissue by inhibiting calcium deposition.

  1. Prevalence of certain inorganic constituents in groundwater samples of Erode district, Tamilnadu, India, with special emphasis on fluoride, fluorosis and its remedial measures.

    PubMed

    Karthikeyan, K; Nanthakumar, K; Velmurugan, P; Tamilarasi, S; Lakshmanaperumalsamy, P

    2010-01-01

    A total of 60 drinking water samples collected from Erode district, Tamilnadu, India were analysed for fluoride contamination, besides water quality parameters such as pH, electrical conductivity, total dissolved solids, total alkalinity, total hardness, fluoride, bicarbonates, calcium, magnesium, nitrate, sulphate, phosphate, sodium and potassium. The results obtained were found to exceed the permissible limits. The concentration of fluoride in the water samples ranged between 0.5 and 8.2 mg/l and revealed that 80% of the water samples contain fluoride above the maximum permissible limit. Similarly, the concentrations of nitrate, hardness, calcium and magnesium in some samples were also more than the permissible level. Pearson's correlation coefficient among the parameters showed a positive correlation of fluoride with total hardness and calcium. It is inferred from the study that these water sources can be used for potable purpose only after prior treatment.

  2. Fluoride occurrence in publicly supplied drinking water in Estonia

    NASA Astrophysics Data System (ADS)

    Karro, Enn; Indermitte, Ene; Saava, Astrid; Haamer, Kadri; Marandi, Andres

    2006-06-01

    A study was undertaken to examine the content and spatial distribution of fluoride in drinking water. Water samples (735) from public water systems covering all Estonian territory were analysed using SPADNS method. In order to specify the natural source of fluoride, the chemistry data from five aquifer systems utilised for water supply were included into the study. Fluoride concentrations in tap water, to a great extent, ranged from 0.01 to 6.95 mg/l. Drinking water in southern Estonia, where terrigenous Middle-Devonian aquifer system is exploited, has a fluoride concentration lower than recommended level (0.5 mg/l), thus promoting susceptibility to dental caries. The western part of the country is supplied by water with excess fluoride content (1.5-6.9 mg/l). Groundwater abstracted for drinking purposes originates from Ordovician and Silurian carbonate rocks. The content of fluoride in Silurian-Ordovician aquifer system is associated with the groundwater abstraction depth and the main controlling factors of dissolved fluoride are the pH value and the chemical type of water.

  3. Butane segregated by fluorides, olefins content at Texas terminals

    SciTech Connect

    Not Available

    1993-03-22

    Texas Eastern Products Pipeline Co., Houston (Teppco), this month has begun segregating butane streams at the company's Mont Belvieu and Baytown, Texas terminals according to fluoride and olefin contents. Streams containing fluoride or an olefin content greater than 1 ppm (or both) currently flow into Teppco's south Mont Belvieu terminal. Those fluoride-free streams with less than 1 ppm of olefins flow to its north Mont Belvieu terminal. Butane processed through an isomerization unit yields isobutane, a key component in MTBE. But high-fluoride butane from crude-oil refineries using hydrofluoric (HF) acid alkylation units cannot be used to produce MTBE because fluoride will damage isomerization units' process catalysts. Olefins also affect the efficiency of isomerization units, but less critically than fluorides. Their presence is higher in refinery product than in fractionated NGL. To extend the life of their process catalysts and to maximize yields, producers (including MTBE and isomerization unit operators) are specifying low-fluoride butanes developed from natural-gas fractionators or from refineries that do not use an HF process.

  4. Health Effects Associated with Water Fluoridation.

    ERIC Educational Resources Information Center

    Richmond, Virginia L.

    1979-01-01

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

  5. Magnesium fluoride recovery method

    DOEpatents

    Gay, Richard L.; McKenzie, Donald E.

    1989-01-01

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

  6. Effects of fluoride on in vitro enamel demineralization analyzed by ¹⁹F MAS-NMR.

    PubMed

    Mohammed, N R; Kent, N W; Lynch, R J M; Karpukhina, N; Hill, R; Anderson, P

    2013-01-01

    The mechanistic action of fluoride on inhibition of enamel demineralization was investigated using (19)F magic angle spinning nuclear magnetic resonance (MAS-NMR). The aim of this study was to monitor the fluoride-mineral phase formed on the enamel as a function of the concentration of fluoride ions [F(-)] in the demineralizing medium. The secondary aim was to investigate fluorapatite formation on enamel in the mechanism of fluoride anti-caries efficacy. Enamel blocks were immersed into demineralization solutions of 0.1 M acetic acid (pH 4) with increasing concentrations of fluoride up to 2,262 ppm. At and below 45 ppm [F(-)] in the solution, (19)F MAS-NMR showed fluoride-substituted apatite formation, and above 45 ppm, calcium fluoride (CaF2) formed in increasing proportions. Further increases in [F(-)] caused no further reduction in demineralization, but increased the proportion of CaF2 formed. Additionally, the combined effect of strontium and fluoride on enamel demineralization was also investigated using (19)F MAS-NMR. The presence of 43 ppm [Sr(2+)] in addition to 45 ppm [F(-)] increases the fraction of fluoride-substituted apatite, but delays formation of CaF2 when compared to the demineralization of enamel in fluoride-only solution. PMID:23712030

  7. IMPACT OF FLUORIDE ON DENTAL HEALTH QUALITY

    PubMed Central

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

    2015-01-01

    Introduction: Fluoride is natural element that strengthens teeth and prevents their decay. Experts believe that the best way to prevent cavities is the use of fluoride from multiple sources. Studies even show that in some cases, fluoride can stop already started damage of the teeth. In children younger than 6 years fluoride is incorporated into the enamel of permanent teeth, making the teeth more resistant to the action of bacterial and acids in food. Goal: The aim of this study is to determine the effects of improving the health status of teeth after six months treatment with the use of topical fluoridation 0.5% NaF, and the level and quality of the impact of treatment with chemical 0.5% NaF on the dental health of children at age from 8 to 15 years, in relation to gender and chronological age. This study included school children aged 8 to 15 years who visited health and dental services dependent in Mostar. Results: It is obvious that after the implementation of treatment with 5% NaF by the method of topical fluoridation, health status of subjects from the experimental group significantly improved, so that at the final review 89.71% or 61 subjects of the experimental group had healthy (cured teeth), tooth with dental caries only 5.88% or 4 respondents tooth with dental caries and filling 4.41% or 3 respondents, extracted baby tooth 14.71% or 10 respondents, while for 13.24% of respondents was identified state with still unerupted teeth. Our findings are indirectly confirmed that the six-month treatment of fluoridation with 5% NaF, contributed to statistically significant improvement in overall oral health of the experimental group compared to the control group which was not treated by any dental treatment. Conclusion: It can be concluded that there is a statistically significant difference in the evaluated parameters of oral health of children in the control group compared to the studied parameters of oral health the experimental group of children at the final

  8. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown...

  9. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown...

  10. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown...

  11. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown...

  12. Influence of Phosphatidylcholine and Calcium on Self-Association and Bile Salt Mixed Micellar Binding of the Natural Bile Pigment, Bilirubin Ditaurate.

    PubMed

    Neubrand, Michael W; Carey, Martin C; Laue, Thomas M

    2015-11-17

    Recently [Neubrand, M. W., et al. (2015) Biochemistry 54, 1542-1557], we determined a concentration-dependent monomer-dimer-tetramer equilibrium in aqueous bilirubin ditaurate (BDT) solutions and explored the nature of high-affinity binding of BDT monomers with monomers and micelles of the common taurine-conjugated bile salts (BS). We now investigate, employing complementary physicochemical methods, including fluorescence emission spectrophotometry and quasi-elastic light scattering spectroscopy, the influence of phosphatidylcholine (PC), the predominant phospholipid of bile and calcium, the major divalent biliary cation, on these self-interactions and heterointeractions. We have used short-chain, lyso and long-chain PC species as models and contrasted our results with those of parallel studies employing unconjugated bilirubin (UCB) as the fully charged dianion. Both bile pigments interacted with the zwitterionic headgroup of short-chain lecithins, forming water-soluble (BDT) and insoluble ion-pair complexes (UCB), respectively. Upon micelle formation, BDT monomers apparently remained at the headgroup mantle of short-chain PCs, but the ion pairs with UCB became internalized within the micelle's hydrophobic core. BDT interacted with the headgroups of unilamellar egg yolk (EY) PC vesicles; however, with the simultaneous addition of CaCl2, a reversible aggregation took place, but not vesicle fusion. With mixed EYPC/BS micelles, BDT became bound to the hydrophilic surface (as with simple BS micelles), and in turn, both BDT and BS bound calcium, but not other divalent cations. The calcium complexation of BDT and BS was enhanced strongly with increases in micellar EYPC, suggesting calcium-mediated cross-bridging of hydrophilic headgroups at the micelle's surface. Therefore, the physicochemical binding of BDT to BS in an artificial bile medium is influenced not only by BS species and concentration but also by long-chain PCs and calcium ions that exert a specific rather

  13. Influence of Phosphatidylcholine and Calcium on Self-Association and Bile Salt Mixed Micellar Binding of the Natural Bile Pigment, Bilirubin Ditaurate.

    PubMed

    Neubrand, Michael W; Carey, Martin C; Laue, Thomas M

    2015-11-17

    Recently [Neubrand, M. W., et al. (2015) Biochemistry 54, 1542-1557], we determined a concentration-dependent monomer-dimer-tetramer equilibrium in aqueous bilirubin ditaurate (BDT) solutions and explored the nature of high-affinity binding of BDT monomers with monomers and micelles of the common taurine-conjugated bile salts (BS). We now investigate, employing complementary physicochemical methods, including fluorescence emission spectrophotometry and quasi-elastic light scattering spectroscopy, the influence of phosphatidylcholine (PC), the predominant phospholipid of bile and calcium, the major divalent biliary cation, on these self-interactions and heterointeractions. We have used short-chain, lyso and long-chain PC species as models and contrasted our results with those of parallel studies employing unconjugated bilirubin (UCB) as the fully charged dianion. Both bile pigments interacted with the zwitterionic headgroup of short-chain lecithins, forming water-soluble (BDT) and insoluble ion-pair complexes (UCB), respectively. Upon micelle formation, BDT monomers apparently remained at the headgroup mantle of short-chain PCs, but the ion pairs with UCB became internalized within the micelle's hydrophobic core. BDT interacted with the headgroups of unilamellar egg yolk (EY) PC vesicles; however, with the simultaneous addition of CaCl2, a reversible aggregation took place, but not vesicle fusion. With mixed EYPC/BS micelles, BDT became bound to the hydrophilic surface (as with simple BS micelles), and in turn, both BDT and BS bound calcium, but not other divalent cations. The calcium complexation of BDT and BS was enhanced strongly with increases in micellar EYPC, suggesting calcium-mediated cross-bridging of hydrophilic headgroups at the micelle's surface. Therefore, the physicochemical binding of BDT to BS in an artificial bile medium is influenced not only by BS species and concentration but also by long-chain PCs and calcium ions that exert a specific rather

  14. Fluoride in groundwater, Varaha River Basin, Visakhapatnam District, Andhra Pradesh, India.

    PubMed

    Rao, N Subba

    2009-05-01

    Excess intake of fluoride through drinking water causes fluorosis on human beings in many States of the country (India), including Andhra Pradesh. Groundwater quality in the Varaha River Basin located in the Visakhapatnam District of Andhra Pradesh has been studied, with reference to fluoride content, for its possible sources for implementing appropriate management measures, according to the controlling mechanism of fluoride concentration in the groundwater. The area occupied by the river basin is underlain by the Precambrian Eastern Ghats, over which the Recent sediments occur. Results of the chemical data of the groundwater suggest that the considerable number of groundwater samples show fluoride content greater than that of the safe limit prescribed for drinking purpose. Statistical analysis shows that the fluoride has a good positive relation, with pH and bicarbonate. This indicates an alkaline environment, as a dominant controlling mechanism for leaching of fluoride from the source material. Other supplementary factors responsible for the occurrence of fluoride in the groundwater are evapotranspiration, long contact time of water with the aquifer material, and agricultural fertilizers. A lack of correlation between fluoride and chloride, and a high positive correlation between fluoride and bicarbonate indicate recharge of the aquifer by the river water. However, the higher concentration of fluoride observed in the groundwater in some locations indicates insufficient dilution by the river water. That means the natural dilution did not perform more effectively. Hence, the study emphasizes the need for surface water management structures, with people's participation, for getting more effective results.

  15. Fluoride in groundwater, Varaha River Basin, Visakhapatnam District, Andhra Pradesh, India.

    PubMed

    Rao, N Subba

    2009-05-01

    Excess intake of fluoride through drinking water causes fluorosis on human beings in many States of the country (India), including Andhra Pradesh. Groundwater quality in the Varaha River Basin located in the Visakhapatnam District of Andhra Pradesh has been studied, with reference to fluoride content, for its possible sources for implementing appropriate management measures, according to the controlling mechanism of fluoride concentration in the groundwater. The area occupied by the river basin is underlain by the Precambrian Eastern Ghats, over which the Recent sediments occur. Results of the chemical data of the groundwater suggest that the considerable number of groundwater samples show fluoride content greater than that of the safe limit prescribed for drinking purpose. Statistical analysis shows that the fluoride has a good positive relation, with pH and bicarbonate. This indicates an alkaline environment, as a dominant controlling mechanism for leaching of fluoride from the source material. Other supplementary factors responsible for the occurrence of fluoride in the groundwater are evapotranspiration, long contact time of water with the aquifer material, and agricultural fertilizers. A lack of correlation between fluoride and chloride, and a high positive correlation between fluoride and bicarbonate indicate recharge of the aquifer by the river water. However, the higher concentration of fluoride observed in the groundwater in some locations indicates insufficient dilution by the river water. That means the natural dilution did not perform more effectively. Hence, the study emphasizes the need for surface water management structures, with people's participation, for getting more effective results. PMID:18509735

  16. Method of repressing the precipitation of calcium fluozirconate

    DOEpatents

    Newby, B.J.; Rhodes, D.W.

    1973-12-25

    Boric acid or a borate salt is added to aqueous solutions of fluoride containing radioactive wastes generated during the reprocessing of zirconium alloy nuclear fuels which are to be converted to solid form by calcining in a fluidized bed. The addition of calcium nitrate to the aqueous waste solutions to prevent fluoride volatility during calcination, causes the precipitation of calcium fluozirconate, which tends to form a gel at fluoride concentrations of 3.0 M or greater. The boron containing species introduced into the solution by the addition of the boric acid or borate salt retard the formation of the calcium fluozirconate precipitate and prevent formation of the gel. These boron containing species can be introduced into the solution by the addition of a borate salt but preferably are introduced by the addition of an aqueous solution of boric acid. (Official Gazette)

  17. Evaluation of natural tracers in an acidic and metal-rich stream

    SciTech Connect

    Bencala, K.E.; McKnight, D.M.; Zellweger, G.W.

    1987-05-01

    In natural waters, a variety of solutes would be appropriate for use as tracers in different situations. Comparisons were made of natural tracers at the confluence of an acidic stream (Snake River) with a pristine stream (Deer Creek) near Montezuma, Colorado. Three comparisons were made during late summer at low-flow conditions to identify the naturally occurring conservative solutes in the stream system: (1) a steady injection of chloride and sodium was used as an artificial, conservative baseline tracer to compare the behavior of silica, sulfate, and fluoride, (2) within the mixing zone of the confluence, comparisons were made of the lateral concentration gradients of sodium, calcium, magnesium, silica, sulfate, and fluoride, and (3) the conservative behavior of naturally occurring calcium, magnesium, silica, sulfate, fluoride, and manganese was evaluated from stream samples collected on four different days. On the basis of the results of these comparisons, manganese and sulfate were used as conservative solutes to demonstrate computation of: (1) the reactive losses of other solutes within the confluence and (2) the ratio of chemical inflows from Deer Creek and the Snake River. The approach used in this evaluation can be applied in the study of chemically similar acidic systems.

  18. Evaluation of Natural Tracers in an Acidic and Metal-Rich Stream

    NASA Astrophysics Data System (ADS)

    Bencala, Kenneth E.; McKnight, Diane M.; Zellweger, Gary W.

    1987-05-01

    In natural waters, a variety of solutes would be appropriate for use as tracers in different situations. Comparisons were made of natural tracers at the confluence of an acidic stream (Snake River) with a pristine stream (Deer Creek) near Montezuma, Colorado. Three comparisons were made during late summer at low-flow conditions to identify the naturally occurring conservative solutes in the stream system: (1) a steady injection of chloride and sodium was used as an artificial, conservative baseline tracer to compare the behavior of silica, sulfate, and fluoride, (2) within the mixing zone of the confluence, comparisons were made of the lateral concentration gradients of sodium, calcium, magnesium, silica, sulfate, and fluoride, and (3) the conservative behavior of naturally occurring calcium, magnesium, silica, sulfate, fluoride, and manganese was evaluated from stream samples collected on four different days. On the basis of the results of these comparisons, manganese and sulfate were used as conservative solutes to demonstrate computation of: (1) the reactive losses of other solutes within the confluence and (2) the ratio of chemical inflows from Deer Creek and the Snake River. The approach used in this evaluation can be applied in the study of chemically similar acidic systems.

  19. A critical study on efficiency of different materials for fluoride removal from aqueous media

    PubMed Central

    2013-01-01

    Fluoride is a persistent and non-biodegradable pollutant that accumulates in soil, plants, wildlife and in human beings. Therefore, knowledge of its removal, using best technique with optimum efficiency is needed. The present survey highlights on efficacy of different materials for the removal of fluoride from water. The most important results of extensive studies on various key factors (pH, agitation time, initial fluoride concentration, temperature, particle size, surface area, presence and nature of counter ions and solvent dose) fluctuate fluoride removal capacity of materials are reviewed. PMID:23497619

  20. Contribution to the physicochemical rationale for the caries reducing effect of fluoride.

    PubMed

    Driessens, F C; Van Dijk, J W; Borggreven, J M; Verbeeck, R M

    1980-09-01

    The effect of fluoride on the stability of apatites containing Na+ and CO3(2)- ions is described qualitatively. Also the boundaries of the apatite stability field in the quasi-septary system CaO - P2O5 - H2O - Na2O - CO2 - NaF - MX are presented. At these boundaries brushite (or monetite), octocalciumphosphate, calcite and calcium fluoride can become stable solid phases. As a consequence, certain mechanisms for the caries reducing effect of fluoride gain probability over other proposed mechanisms. First, it is likely that endemic fluoride yields more fully mineralized enamel which in turn results in a lower initial rate of the caries process. Second, after eruption the mineral in the tooth superficial layer is bound to accumulate fluoride on the surface of its crystals. This causes a slower rate of the crystal surface dissolution at that site and, hence, a thicker and denser intact superficial layer over the lesion. Finally, the formation of a precipitate of fluorhydroxyapatite and perhaps also of calcium fluoride is promoted in the plaque during cycles of metabolic activity. Subsequent dissolution of the CaF2 and transformation of the fluorhydroxyapatite sets free Ca+ and F- ions. Both of these ions promote the remineralization of the lesion during periods of metabolic rest whereby brushite or monetite are transformed back into apatite.

  1. Fluoride Content in Alcoholic Drinks.

    PubMed

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

    2016-06-01

    The aim of the study was to determine the role of alcoholic drinks as a potential source of dietary fluoride by means of measuring fluoride levels in selected alcoholic drinks available on the Polish market that are also diverse in terms of the percentage content of ethanol. The study was conducted on 48 types of drinks with low, medium, and high alcohol content available on the Polish market and offered by various manufacturers, both Polish and foreign. Fluoride concentrations in individual samples were measured by potentiometric method with a fluoride ion-selective electrode. The highest fluoride levels were determined in the lowest percentage drinks (less than 10 % v/v ethanol), with the lowest fluoride levels observed in the highest percentage drinks (above 40 % v/v ethanol). In terms of types of alcoholic drinks, the highest fluoride levels were determined in beers and wines, while the lowest levels were observed in vodkas. These data confirm the fact that alcoholic beverages need to be considered as a significant source of fluoride delivered into the body. PMID:26475300

  2. WET FLUORIDE SEPARATION METHOD

    DOEpatents

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

    1958-11-25

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

  3. Examination of Liquid Fluoride Salt Heat Transfer

    SciTech Connect

    Yoder Jr, Graydon L

    2014-01-01

    The need for high efficiency power conversion and energy transport systems is increasing as world energy use continues to increase, petroleum supplies decrease, and global warming concerns become more prevalent. There are few heat transport fluids capable of operating above about 600oC that do not require operation at extremely high pressures. Liquid fluoride salts are an exception to that limitation. Fluoride salts have very high boiling points, can operate at high temperatures and low pressures and have very good heat transfer properties. They have been proposed as coolants for next generation fission reactor systems, as coolants for fusion reactor blankets, and as thermal storage media for solar power systems. In each case, these salts are used to either extract or deliver heat through heat exchange equipment, and in order to design this equipment, liquid salt heat transfer must be predicted. This paper discusses the heat transfer characteristics of liquid fluoride salts. Historically, heat transfer in fluoride salts has been assumed to be consistent with that of conventional fluids (air, water, etc.), and correlations used for predicting heat transfer performance of all fluoride salts have been the same or similar to those used for water conventional fluids an, water, etc). A review of existing liquid salt heat transfer data is presented, summarized, and evaluated on a consistent basis. Less than 10 experimental data sets have been found in the literature, with varying degrees of experimental detail and measured parameters provided. The data has been digitized and a limited database has been assembled and compared to existing heat transfer correlations. Results vary as well, with some data sets following traditional correlations; in others the comparisons are less conclusive. This is especially the case for less common salt/materials combinations, and suggests that additional heat transfer data may be needed when using specific salt eutectics in heat transfer

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

    SciTech Connect

    Baumann, E.W.

    2003-01-06

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

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  6. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2010 CFR

    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...

  7. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

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

  8. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

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

  9. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

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

  10. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

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

  11. Geochemical controls of high fluoride groundwater in Umarkot Sub-District, Thar Desert, Pakistan.

    PubMed

    Rafique, Tahir; Naseem, Shahid; Ozsvath, David; Hussain, Riaz; Bhanger, Muhammad Iqbal; Usmani, Tanzil Haider

    2015-10-15

    Groundwater samples (n=152) were collected in the Thar Desert of the Umarkot Sub-District, Pakistan to evaluate the geochemical controls on the occurrence of high fluoride (F(-)) levels within the study area. Fluoride concentrations range from 0.06 to 44.4 mg/L, with mean and median values of 5.22 and 4.09 mg/L, respectively; and roughly 84% of the samples contain fluoride concentrations that exceed the 1.5mg/L drinking water standard set by WHO. The overall groundwater quality reflects the influences of silicate mineral weathering and evaporation. Fluoride originates from the weathering of minerals derived from Type-A granite and possibly anion exchange (OH(-) for F(-)) on clays and weathered micas under high pH conditions. High fluoride levels are associated with Na-HCO3 type water produced by calcite precipitation and/or base ion exchange. Depleted calcium levels in groundwater allow higher fluoride concentrations to occur before the solubility limit for fluoride is reached. PMID:26047861

  12. Geochemical controls of high fluoride groundwater in Umarkot Sub-District, Thar Desert, Pakistan.

    PubMed

    Rafique, Tahir; Naseem, Shahid; Ozsvath, David; Hussain, Riaz; Bhanger, Muhammad Iqbal; Usmani, Tanzil Haider

    2015-10-15

    Groundwater samples (n=152) were collected in the Thar Desert of the Umarkot Sub-District, Pakistan to evaluate the geochemical controls on the occurrence of high fluoride (F(-)) levels within the study area. Fluoride concentrations range from 0.06 to 44.4 mg/L, with mean and median values of 5.22 and 4.09 mg/L, respectively; and roughly 84% of the samples contain fluoride concentrations that exceed the 1.5mg/L drinking water standard set by WHO. The overall groundwater quality reflects the influences of silicate mineral weathering and evaporation. Fluoride originates from the weathering of minerals derived from Type-A granite and possibly anion exchange (OH(-) for F(-)) on clays and weathered micas under high pH conditions. High fluoride levels are associated with Na-HCO3 type water produced by calcite precipitation and/or base ion exchange. Depleted calcium levels in groundwater allow higher fluoride concentrations to occur before the solubility limit for fluoride is reached.

  13. Study of fluoride content in groundwater of Nawa Tehsil in Nagaur, Rajasthan.

    PubMed

    Gautam, Radha; Bhardwaj, Nagendra; Saini, Yashoda

    2011-01-01

    There is a severe fluoride problem in Nawa tehsil of Nagaur district. Villagers are suffering from dental fluorosis and skeletal fluorosis. So an extensive geochemical study of 27 villages of eastern, south-eastern and southern zone of Nawa tehsil was done. Total 46 ground water samples were collected and analyzed for various physicochemical parameters as well as fluoride content. The ground water samples collected in clean polyethylene plastic containers were analyzed for pH, electrical conductivity, total dissolved salts, calcium, magnesium, total hardness, chloride and alkalinity. The fluoride concentration in the three different zones ranged from 0.64 to 14.62 mg l(-1) where 13.04% samples were found within permissible limit while 86.96% had fluoride beyond permissible limit (> 1.5 mg l(-1)). It was found that among the three different zones south-eastern zone was under serious fluoride contamination where fluoride concentration ranged between 1.10 to 14.62 mg l(-1). In the eastern zone fluoride concentration was recorded from 1.52 to 5.13 mg l(-1) whereas in the southern zone it was found between 0.64 to 3.63 mg l(-1).

  14. Vapor-liquid equilibria for the systems difluoromethane + hydrogen fluoride, dichlorodifluoromethane + hydrogen fluoride, and chlorine + hydrogen fluoride

    SciTech Connect

    Kang, Y.W.

    1998-01-01

    Isothermal vapor-liquid equilibria for difluoromethane + hydrogen fluoride, dichlorodifluoromethane + hydrogen fluoride, and chlorine + hydrogen fluoride have been measured. The experimental data for the binary systems are correlated with the NRTL equation with the vapor-phase association model for the mixtures containing hydrogen fluoride, and the relevant parameters are presented. The binary system difluoromethane + hydrogen fluoride forms a homogeneous liquid phase, and the others form minimum boiling heterogeneous azeotropes at the experimental conditions.

  15. Separation of cyclotron-produced 44Sc from a natural calcium target using a dipentyl pentylphosphonate functionalized extraction resin

    PubMed Central

    Valdovinos, H.F.; Hernandez, R.; Barnhart, T.E.; Graves, S.; Cai, W.; Nickles, R.J.

    2014-01-01

    Significant interest in 44Sc as a radioactive synthon to label small molecules for positron emission tomography (PET) imaging has been recently observed. Despite the efforts of several research groups, the ideal 44Sc production and separation method remains elusive. Herein, we propose a novel separation method to obtain 44Sc from the proton irradiation of calcium targets based on extraction chromatography, which promises to greatly simplify current production methodologies. Using the commercially available Uranium and Tetravalent Actinides (UTEVA) extraction resin we were able to rapidly (< 20 min) recover > 80% of the activity generated at end of bombardment (EoB) in small ~1 M HCl fractions (400 μL). The chemical purity of the 44Sc eluates was evaluated through chelation with DOTA and DTPA, and by trace metal analysis using microwave induced plasma atomic emission spectrometry. The distribution coefficients (Kd) of Sc(III) and Ca(II) in UTEVA were determined in HCl medium in a range of concentrations from zero to 12.1 M The 44Sc obtained with our method proved to be suitable for the direct labeling of small biomolecules for PET imaging, with excellent specific activities and radiochemical purity. PMID:25464172

  16. Reducing Exposure to High Fluoride Drinking Water in Estonia—A Countrywide Study

    PubMed Central

    Indermitte, Ene; Saava, Astrid; Karro, Enn

    2014-01-01

    Fluoride is a naturally occurring contaminant in groundwater in Estonia. There are several regions in Estonia with fluoride contents in public water supplies as high as 7 mg/L. Long-term exposure to high-fluoride drinking water may have several adverse health effects, primarily dental fluorosis. The opportunities for exposure reduction rely highly on water treatment technologies. Since 2004 public water suppliers in Estonia have made efforts to diminish fluoride content in drinking water systems. A follow-up study on a country level was carried out in 2004–2012 to analyze the changes in population exposure to excessive (over 1.5 mg/L) fluoride in drinking water and to get information about the reduction methods applied by public water supplies (PWS) to optimize the fluoride levels in public water system. The results showed that bigger PWS have been more effective in fluoride reduction measures than small PWS. The main methods used to lower the fluoride content were reverse osmosis technology and replacement of water sources with new ones (new drilled wells). As a result of all the measures taken the overall high-fluoride exposure has been reduced substantially (82%). PMID:24637908

  17. Reducing exposure to high fluoride drinking water in Estonia-a countrywide study.

    PubMed

    Indermitte, Ene; Saava, Astrid; Karro, Enn

    2014-03-14

    Fluoride is a naturally occurring contaminant in groundwater in Estonia. There are several regions in Estonia with fluoride contents in public water supplies as high as 7 mg/L. Long-term exposure to high-fluoride drinking water may have several adverse health effects, primarily dental fluorosis. The opportunities for exposure reduction rely highly on water treatment technologies. Since 2004 public water suppliers in Estonia have made efforts to diminish fluoride content in drinking water systems. A follow-up study on a country level was carried out in 2004-2012 to analyze the changes in population exposure to excessive (over 1.5 mg/L) fluoride in drinking water and to get information about the reduction methods applied by public water supplies (PWS) to optimize the fluoride levels in public water system. The results showed that bigger PWS have been more effective in fluoride reduction measures than small PWS. The main methods used to lower the fluoride content were reverse osmosis technology and replacement of water sources with new ones (new drilled wells). As a result of all the measures taken the overall high-fluoride exposure has been reduced substantially (82%).

  18. Evaluating the impact of municipal water fluoridation on the aquatic environment.

    PubMed Central

    Osterman, J W

    1990-01-01

    Although highly beneficial for dental health, low concentrations of fluoride in environmental waters may be toxic to several organisms. In an era of heightened public awareness about the environment, this may lead city officials to withhold implementing water fluoridation for environmental reasons. This paper presents a mass balance approach to evaluate this perceived risk. Generally speaking, fluoridated water loss during use, dilution of sewage by rain and ground water infiltrate, fluoride removal during secondary sewage treatment, and diffusion dynamics at effluent outfall combine to eliminate fluoridation-related environmental effects. In Montreal, water fluoridation would raise average aquatic fluoride levels in the waste water plume immediately below effluent outfall by only 0.05-0.09 mg/l. Downstream, these changes would be only 0.02-0.05 mg/l at 1 km, and 0.01-0.03 mg/l at 2 km below outfall. Overall river fluoride concentrations theoretically would be raised by 0.001-0.002 mg/l, a value not measurable by current analytical techniques. All resulting concentrations would be well below those recommended for environmental safety and would not exceed natural levels found elsewhere in Quebec. A literature review did not reveal any examples of municipal water fluoridation causing recommended environmental concentrations to be exceeded, although excesses occurred in several cases of severe industrial water pollution. PMID:2400035

  19. Molten fluoride fuel salt chemistry

    NASA Astrophysics Data System (ADS)

    Toth, L. M.; Del Cul, G. D.; Dai, S.; Metcalf, D. H.

    1995-01-01

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior which can be used effectively to reduce the amount of development required for future systems, some significant molten salt chemical questions must still be addressed.

  20. Molten fluoride fuel salt chemistry

    NASA Astrophysics Data System (ADS)

    Toth, L. M.; Delcul, G. D.; Dai, S.; Metcalf, D. H.

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior which can be used effectively to reduce the amount of development required for future systems, some significant molten salt chemical questions must still be addressed.

  1. Molten fluoride fuel salt chemistry

    NASA Astrophysics Data System (ADS)

    Toth, L. M.; Del Cul, G. D.; Dai, S.; Metcalf, D. H.

    1995-09-01

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

  2. Molten fluoride fuel salt chemistry

    SciTech Connect

    Toth, L.M.; Del Cul, G.D.; Dai, S.; Metcalf, D.H.

    1994-09-01

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

  3. Calcium supplement: humanity's double-edged sword.

    PubMed

    Bunyaratavej, Narong; Buranasinsup, Shutipen

    2011-10-01

    The principle aim of the present study is to investigate the dark side of calcium, pollutions in calcium preparation especially lead (Pb), mercury (Hg) and cadmium (Cd). The collected samples were the different calcium salts in the market and 18 preparations which were classified into 3 groups: Calcium carbonate salts, Chelated calcium and natural-raw calcium. All samples were analyzed for lead, cadmium and mercury by inductively Coupled Plasma Mass Spectrometry (ICP-MS) technique, in house method based on AOAC (2005) 999.10 by ICP-MS. The calcium carbonate and the natural-raw calcium in every sample contained lead at 0.023-0.407 mg/kg of calcium powder. Meanwhile, the natural-raw calcium such as oyster, coral and animal bone showed amount of lead at 0.106-0.384 mg/kg with small amounts of mercury and cadmium. The chelated calcium such as calcium gluconate, calcium lactate and calcium citrate are free of lead. PMID:22338928

  4. Fluorination utilizing thermodynamically unstable fluorides and fluoride salts thereof

    SciTech Connect

    Bartlett, Neil; Whalen, J. Marc; Chacon, Lisa

    2000-12-12

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

  5. On the Nature and Origin of the Calcium Asymmetry Arising during Gravitropic Response in Etiolated Pea Epicotyls 1

    PubMed Central

    Migliaccio, Fernando; Galston, Arthur W.

    1987-01-01

    Seven day old etiolated pea epicotyls were loaded symmetrically with 3H-indole 3-acetic acid (IAA) or 45Ca2+, then subjected to 1.5 hours of 1g gravistimulation. Epidermal peels taken from top and bottom surfaces after 90 minutes showed an increase in IAA on the lower side and of Ca2+ on the upper side. Inhibitors of IAA movement (TIBA, 9-hydroxyfluorene carboxylic acid) block the development of both IAA and Ca2+ asymmetries, but substances known to interfere with normal Ca2+ transport (nitrendipine, nisoldipine, Bay K 8644, A 23187) do not significantly alter either IAA or Ca2+ asymmetries. These substances, however, are active in modifying both Ca2+ uptake and efflux through oat and pea leaf protoplast membranes. We conclude that the 45Ca2+ fed to pea epicotyls occurs largely in the cell wall, and that auxin movement is primary and Ca2+ movement secondary in gravitropism. We hypothesize that apoplastic Ca2+ changes during graviresponse because it is displaced by H+ secreted through auxin-induced proton release. This proposed mechanism is supported by localized pH experiments, in which filter paper soaked in various buffers was applied to one side of a carborundum-abraded epicotyls. Buffer at pH 3 increases calcium loss from the side to which it is applied, whereas pH 7 buffer decreases it. Moreover, 10 micromolar IAA and 1 micromolar fusicoccin, which promote H+ efflux, increase Ca2+ release from pea epicotyl segments, whereas cycloheximide, which inhibits H+ efflux, has the reverse effect. We suggest that Ca2+ does not redistribute actively during gravitropism: the asymmetry arises because of its release from the wall adjacent to the region of high IAA concentration, proton secretion, and growth. Thus, the asymmetric distribution of Ca2+ appears to be a consequence of growth stimulation, not a critical step in the early phase of the graviresponse. Images Fig. 1 Fig. 2 PMID:11539707

  6. On the nature and origin of the calcium asymmetry arising during gravitropic response in etiolated pea epicotyls

    NASA Technical Reports Server (NTRS)

    Migliaccio, F.; Galston, A. W.

    1987-01-01

    Seven day old etiolated pea epicotyls were loaded symmetrically with 3H-indole 3-acetic acid (IAA) or 45Ca2+, then subjected to 1.5 hours of 1g gravistimulation. Epidermal peels taken from top and bottom surfaces after 90 minutes showed an increase in IAA on the lower side and of Ca2+ on the upper side. Inhibitors of IAA movement (TIBA, 9-hydroxyfluorene carboxylic acid) block the development of both IAA and Ca2+ asymmetries, but substances known to interfere with normal Ca2+ transport (nitrendipine, nisoldipine, Bay K 8644, A 23187) do not significantly alter either IAA or Ca2+ asymmetries. These substances, however, are active in modifying both Ca2+ uptake and efflux through oat and pea leaf protoplast membranes. We conclude that the 45Ca2+ fed to pea epicotyls occurs largely in the cell wall, and that auxin movement is primary and Ca2+ movement secondary in gravitropism. We hypothesize that apoplastic Ca2+ changes during graviresponse because it is displaced by H+ secreted through auxin-induced proton release. This proposed mechanism is supported by localized pH experiments, in which filter paper soaked in various buffers was applied to one side of a carborundum-abraded epicotyls. Buffer at pH 3 increases calcium loss from the side to which it is applied, whereas pH 7 buffer decreases it. Moreover, 10 micromolar IAA and 1 micromolar fusicoccin, which promote H+ efflux, increase Ca2+ release from pea epicotyl segments, whereas cycloheximide, which inhibits H+ efflux, has the reverse effect. We suggest that Ca2+ does not redistribute actively during gravitropism: the asymmetry arises because of its release from the wall adjacent to the region of high IAA concentration, proton secretion, and growth. Thus, the asymmetric distribution of Ca2+ appears to be a consequence of growth stimulation, not a critical step in the early phase of the graviresponse.

  7. Naturally occurring radioactive material (NORM) from a former phosphoric acid processing plant.

    PubMed

    Beddow, H; Black, S; Read, D

    2006-01-01

    In recent years there has been an increasing awareness of the radiological impact of non-nuclear industries that extract and/or process ores and minerals containing naturally occurring radioactive material (NORM). These industrial activities may result in significant radioactive contamination of (by-) products, wastes and plant installations. In this study, scale samples were collected from a decommissioned phosphoric acid processing plant. To determine the nature and concentration of NORM retained in pipe-work and associated process plant, four main areas of the site were investigated: (1) the 'Green Acid Plant', where crude acid was concentrated; (2) the green acid storage tanks; (3) the Purified White Acid (PWA) plant, where inorganic impurities were removed; and (4) the solid waste, disposed of on-site as landfill. The scale samples predominantly comprise the following: fluorides (e.g. ralstonite); calcium sulphate (e.g. gypsum); and an assemblage of mixed fluorides and phosphates (e.g. iron fluoride hydrate, calcium phosphate), respectively. The radioactive inventory is dominated by 238U and its decay chain products, and significant fractionation along the series occurs. Compared to the feedstock ore, elevated concentrations (< or =8.8 Bq/g) of 238U were found to be retained in installations where the process stream was rich in fluorides and phosphates. In addition, enriched levels (< or =11 Bq/g) of 226Ra were found in association with precipitates of calcium sulphate. Water extraction tests indicate that many of the scales and waste contain significantly soluble materials and readily release radioactivity into solution.

  8. Naturally occurring radioactive material (NORM) from a former phosphoric acid processing plant.

    PubMed

    Beddow, H; Black, S; Read, D

    2006-01-01

    In recent years there has been an increasing awareness of the radiological impact of non-nuclear industries that extract and/or process ores and minerals containing naturally occurring radioactive material (NORM). These industrial activities may result in significant radioactive contamination of (by-) products, wastes and plant installations. In this study, scale samples were collected from a decommissioned phosphoric acid processing plant. To determine the nature and concentration of NORM retained in pipe-work and associated process plant, four main areas of the site were investigated: (1) the 'Green Acid Plant', where crude acid was concentrated; (2) the green acid storage tanks; (3) the Purified White Acid (PWA) plant, where inorganic impurities were removed; and (4) the solid waste, disposed of on-site as landfill. The scale samples predominantly comprise the following: fluorides (e.g. ralstonite); calcium sulphate (e.g. gypsum); and an assemblage of mixed fluorides and phosphates (e.g. iron fluoride hydrate, calcium phosphate), respectively. The radioactive inventory is dominated by 238U and its decay chain products, and significant fractionation along the series occurs. Compared to the feedstock ore, elevated concentrations (< or =8.8 Bq/g) of 238U were found to be retained in installations where the process stream was rich in fluorides and phosphates. In addition, enriched levels (< or =11 Bq/g) of 226Ra were found in association with precipitates of calcium sulphate. Water extraction tests indicate that many of the scales and waste contain significantly soluble materials and readily release radioactivity into solution. PMID:16303218

  9. Fluoride glass: Crystallization, surface tension

    NASA Technical Reports Server (NTRS)

    Doremus, R. H.

    1988-01-01

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

  10. Do Fluoride Ions Protect Teeth?

    ERIC Educational Resources Information Center

    Parkin, Christopher

    1998-01-01

    Begins with the procedure and results from an investigation on the effect of fluoride on the reaction between eggshell (substitute teeth) and dilute ethanoic acid. Describes an elegantly modified and improvised apparatus. (DDR)

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

    PubMed

    Craig, Laura; Lutz, Alexandra; Berry, Kate A; Yang, Wei

    2015-11-01

    Both dental and skeletal fluorosis caused by high fluoride intake are serious public health concerns around the world. Fluorosis is particularly pronounced in developing countries where elevated concentrations of naturally occurring fluoride are present in the drinking water, which is the primary route of exposure. The World Health Organization recommended limit of fluoride in drinking water is 1.5 mg F(-) L(-1), which is also the upper limit for fluoride in drinking water for several other countries such as Canada, China, India, Australia, and the European Union. In the United States the enforceable limit is much higher at 4 mg F(-) L(-1), which is intended to prevent severe skeletal fluorosis but does not protect against dental fluorosis. Many countries, including the United States, also have notably lower unenforced recommended limits to protect against dental fluorosis. One consideration in determining the optimum fluoride concentration in drinking water is daily water intake, which can be high in hot climates such as in northern Ghana. The results of this study show that average water intake is about two times higher in Ghana than in more temperate climates and, as a result, the fluoride intake is higher. The results also indicate that to protect the Ghanaian population against dental fluorosis, the maximum concentration of fluoride in drinking water for children under 6-8 years should be 0.6 mg F(-) L(-1) (and lower in the first two years of life), and the limit for older children and adults should be 1.0 mg F(-) L(-1). However, when considering that water treatment is not cost-free, the most widely recommended limit of 1.5 mg F(-) L(-1) - which is currently the limit in Ghana--may be appropriate for older children and adults since they are not vulnerable to dental fluorosis once the tooth enamel is formed.

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

    PubMed

    Craig, Laura; Lutz, Alexandra; Berry, Kate A; Yang, Wei

    2015-11-01

    Both dental and skeletal fluorosis caused by high fluoride intake are serious public health concerns around the world. Fluorosis is particularly pronounced in developing countries where elevated concentrations of naturally occurring fluoride are present in the drinking water, which is the primary route of exposure. The World Health Organization recommended limit of fluoride in drinking water is 1.5 mg F(-) L(-1), which is also the upper limit for fluoride in drinking water for several other countries such as Canada, China, India, Australia, and the European Union. In the United States the enforceable limit is much higher at 4 mg F(-) L(-1), which is intended to prevent severe skeletal fluorosis but does not protect against dental fluorosis. Many countries, including the United States, also have notably lower unenforced recommended limits to protect against dental fluorosis. One consideration in determining the optimum fluoride concentration in drinking water is daily water intake, which can be high in hot climates such as in northern Ghana. The results of this study show that average water intake is about two times higher in Ghana than in more temperate climates and, as a result, the fluoride intake is higher. The results also indicate that to protect the Ghanaian population against dental fluorosis, the maximum concentration of fluoride in drinking water for children under 6-8 years should be 0.6 mg F(-) L(-1) (and lower in the first two years of life), and the limit for older children and adults should be 1.0 mg F(-) L(-1). However, when considering that water treatment is not cost-free, the most widely recommended limit of 1.5 mg F(-) L(-1) - which is currently the limit in Ghana--may be appropriate for older children and adults since they are not vulnerable to dental fluorosis once the tooth enamel is formed. PMID:26058000

  13. Selective Adsorption of Sodium Aluminum Fluoride Salts from Molten Aluminum

    SciTech Connect

    Leonard S. Aubrey; Christine A. Boyle; Eddie M. Williams; David H. DeYoung; Dawid D. Smith; Feng Chi

    2007-08-16

    Aluminum is produced in electrolytic reduction cells where alumina feedstock is dissolved in molten cryolite (sodium aluminum fluoride) along with aluminum and calcium fluorides. The dissolved alumina is then reduced by electrolysis and the molten aluminum separates to the bottom of the cell. The reduction cell is periodically tapped to remove the molten aluminum. During the tapping process, some of the molten electrolyte (commonly referred as “bath” in the aluminum industry) is carried over with the molten aluminum and into the transfer crucible. The carryover of molten bath into the holding furnace can create significant operational problems in aluminum cast houses. Bath carryover can result in several problems. The most troublesome problem is sodium and calcium pickup in magnesium-bearing alloys. Magnesium alloying additions can result in Mg-Na and Mg-Ca exchange reactions with the molten bath, which results in the undesirable pickup of elemental sodium and calcium. This final report presents the findings of a project to evaluate removal of molten bath using a new and novel micro-porous filter media. The theory of selective adsorption or removal is based on interfacial surface energy differences of molten aluminum and bath on the micro-porous filter structure. This report describes the theory of the selective adsorption-filtration process, the development of suitable micro-porous filter media, and the operational results obtained with a micro-porous bed filtration system. The micro-porous filter media was found to very effectively remove molten sodium aluminum fluoride bath by the selective adsorption-filtration mechanism.

  14. Fluoride enrichment mechanism and geospatial distribution in the volcanic aquifers of the Middle Awash basin, Northern Main Ethiopian Rift

    NASA Astrophysics Data System (ADS)

    Furi, Wakgari; Razack, Moumtaz; Abiye, Tamiru Alemayehu; Ayenew, Tenalem; Legesse, Dagnachew

    2011-07-01

    Considering the anomalous concentration of fluoride in the ground waters of the Middle Awash basin, a comprehensive survey of the enrichment mechanism as well as its association with common hydrochemical variables was conducted using multivariate statistical methods, Hierarchal Cluster Analysis (HCA) and Principal Component Analysis (PCA). The HCA results indicate a marked heterogeneous spatial distribution of the fluoride concentration, the magnitude of which varies more gradually in the SSW-NNE direction along the Wonji Fault Belt (WFB) than it does in the E-W direction away from this belt. This is strongly associated with the geothermal anomaly that is prominent in the basin interior area. Furthermore, the PCA results show that the magnitude of the fluoride concentration is higher in the groundwater derived from non-calcium bearing aquifers, which are widely distributed in the rift floor. Hydrochemical processes involving a cation exchange reaction cause a systematic Ca 2+ removal from solution from highland towards the rift floor. This geochemical reaction enhances the fluoride enrichment of groundwater along the same flow direction. In this regard, the geothermal belt of the basin interior area is a hydrogeological block marked by high loads of fluoride whereas the plateau areas are low-fluoride zones. The geospatial distribution of fluoride at the basin scale was estimated using the kriging procedure. Appropriate discrimination between local and regional aquifers is important in order to secure low-fluoride water supply for the community in the basin.

  15. Fluoride enrichment in groundwater of semi-arid urban area: Khan Younis City, southern Gaza Strip (Palestine)

    NASA Astrophysics Data System (ADS)

    Abu Jabal, Mohamed Shaban; Abustan, Ismail; Rozaimy, Mohd Remy; Al-Najar, Hussam

    2014-12-01

    The aim of this study is to determine fluoride enhancement in the groundwater of semi-arid urban area of Khan Younis City, southern Gaza Strip. Physicochemical data for a total of 200 groundwater samples were analyzed. The fluoride concentrations were varied from 0.3 to 6.45 mg/L with average value of 2.87 mg/L. Correlations between fluorides with other measured ions were relatively observed, negative correlation with calcium and the positive correlation with pH, bicarbonate and sodium increase the dissolution/solubility of fluoride bearing minerals, leading to fluoride leaching into the groundwater. Fluoride enrichment in the groundwater of the area is due to water hydrochemistry, mineral-water interaction (mainly calcite and fluorite), fluorite resulted from fluorapatite dissolution. The saturation indexes evaluation indicated that 42% of the samples are over saturated with respect to calcite and 35.5% under saturated with respect to fluorite, while 40.5% approached equilibrium with respect to both calcite and fluorite. At fluoride concentrations of less than 2.2 mg/L fluorite saturation indexes show under-saturation condition for fluorite and at higher fluoride concentrations show near saturation condition.

  16. Removal of fluoride from aqueous solution by using alum sludge

    SciTech Connect

    Sujana, M.G.; Thakur, R.S.; Rao, S.B.

    1998-10-01

    The ability of treated alum sludge to remove fluoride from aqueous solution has been investigated. The studies were carried out as functions of contact time, concentration of adsorbent and adsorbate, temperature, pH, and effect of concentrations of other anions. The data indicate that treated alum sludge surface sites are heterogeneous in nature and that fits into a heterogeneous site binding model. The optimum pH for complete removal of fluoride from aqueous solution was found to be 6. The rate of adsorption was rapid during the initial 5 minutes, and equilibrium was attained within 240 minutes. The adsorption followed first-order rate kinetics. The present system followed the Langmuir adsorption isotherm model. The loading factor (i.e., the milligram of fluoride adsorbed per gram of alum sludge) increased with initial fluoride concentration, whereas a negative trend was observed with increasing temperature. The influence of addition of anions on fluoride removal depends on the relative affinity of the anions for the surface and the relative concentrations of the anions.

  17. Calcium in diet

    MedlinePlus

    ... of calcium dietary supplements include calcium citrate and calcium carbonate. Calcium citrate is the more expensive form of ... the body on a full or empty stomach. Calcium carbonate is less expensive. It is absorbed better by ...

  18. 21 CFR 184.1206 - Calcium iodate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium iodate. 184.1206 Section 184.1206 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD....1206 Calcium iodate. (a) Calcium iodate , also referred to as lautarite, does not occur naturally...

  19. The circumvention of the natural biopurification of calcium along nutrient pathways by atmospheric inputs of industrial lead

    NASA Astrophysics Data System (ADS)

    Elias, Robert W.; Hirao, Yoshimitsu; Patterson, Clair C.

    1982-12-01

    Biopurification factors for Ca with respect to Sr, Ba, and natural, uncontaminated Pb were measured for different nutrient-consumer pairs in a remote subalpine ecosystem. The factor for Sr is expressed as: (nutrient Sr/Ca) ÷ (consumer Sr/Ca). Similar expressions were used for Ba/Ca and Pb/Ca. It was found that Ca was biopurified of Sr 3-fold, of Ba 16-fold, and of Pb 100-fold in going from rock to sedge leaves. In going from sedge leaf to vole, Ca was biopurified of Sr 4-fold, of Ba 8-fold, and of Pb 16-fold. In going from meadow vole to pine marten, Ca was biopurified of Sr 6-fold, of Ba 7-fold, and of Pb 1.1-fold. Similar ranges of values for these factors were obtained for detrital and amphibian food chains. Fluxes of industrial lead entering the ecosystem as precipitation and dry deposition were measured and it was found that 40% of the lead in soil humus and soil moisture, 82% of the lead in sedge leaves, 92% of the lead in vole, and 97% of the lead in marten was industrial. The natural skeletal Pb/Ca ratio in carnivores (4 × 10 -8) was determined by means of corrections for inputs of industrial lead, food chain relationships, and measured biopurification factors for the ecosystem studied. This represents a 1700-fold reduction of the average Pb/Ca ratio in igneous rocks at the earth's surface (6.4 × 10 -5) by the compounding of successive Pb biopurification factors in transferring Ca from rock to carnivore. The natural ratio is similar to the value of 6 × 10 -8 observed for Pb/Ca in the bones of Peruvians who lived 2000 years ago but is 1/900th of the value of about 3.5 × 10 -5 for the skeletal Pb/Ca ratio found in present day Americans. This study shows experimentally how the Ba/Ca ratio in average surface igneous rock (3 × 10 -3) has been reduced 800-fold through compounding of successive biopurification steps to provide the skeletal Ba/Ca ratio of about 4 × 10 -6 observed in humans. It also provides biopurification factors for Sr and Ba among a

  20. Chronic Fluoride Toxicity: Dental Fluorosis

    PubMed Central

    DenBesten, Pamela; Li, Wu

    2012-01-01

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

  1. Influence of cadmium on caries and the cariostatic properties of fluoride in rats

    SciTech Connect

    Shearer, T.R.; Britton, J.L.; DeSart, D.J.; Johnson, J.R.

    1980-05-01

    Cadmium injections during molar tooth development in the rat were strongly caries-promoting in female rats. Cadmium also partially negated the cariostatic effect of fluoridated drinking water in both male and female rats. The mechanism for the caris-promoting propeties of cadmium is unknown, but may be related to cadmium uptake into enamel and dentin. Cadmium was taken up into molar enamel and dentin in proportion to the amount of cadmium administered, but cadmium did not influence uptake of fluoride onto erupted enamel. Calcium and ash concentrations in molar enamel were not altered by cadmium administration.

  2. Calcium Test

    MedlinePlus

    ... as thyroid disease , parathyroid disorder , malabsorption , cancer, or malnutrition An ionized calcium test may be ordered when ... albumin , which can result from liver disease or malnutrition , both of which may result from alcoholism or ...

  3. Calcium Calculator

    MedlinePlus

    ... with Sarcopenia Skeletal Rare Disorders Data & Publications Facts and Statistics Vitamin D map Fracture Risk Map Hip Fracture ... Training Courses Working Groups Regional Audits Reports Facts and Statistics Popular content Calcium content of common foods What ...

  4. The role of Fe(III) modified montmorillonite on fluoride mobility: adsorption experiments and competition with phosphate.

    PubMed

    Bia, Gonzalo; De Pauli, Carlos P; Borgnino, Laura

    2012-06-15

    Fluoride adsorption onto Fe(III) modified montmorillonite was investigated using batch experiments. The effect of reaction time, pH, ionic strength and phosphate, as a competitive anion, was evaluated. Kinetics indicated that adsorption obeys a pseudo-first-order rate law which involves two steps. The fast one (bulk transport/surface reaction) occurs instantaneously. The slower (diffusion in pores) takes hours to complete. The adsorption rate increases by increasing the fluoride concentration and by decreasing pH. The presence of phosphate reduces fluoride adsorption and reveals that both ions are in competition for surface sites. The reduction in fluoride adsorption when phosphate is present depends on the order of adsorbate addition. The higher fluoride adsorption occurs when both anions are added simultaneously, whereas when either fluoride or phosphate is added first, the fluoride adsorption is lower. The presence of fluoride does not have a measurable effect on phosphate adsorption. The results obtained contribute to our understanding of the mobility of fluoride in surface water which has naturally high levels of fluoride, in both the presence and absence of phosphate.

  5. Classical trajectories studies of DIET from calcium fluoride

    NASA Astrophysics Data System (ADS)

    Ciepliński, L.; Jedrzejek, C.

    1995-10-01

    We investigate desorption of positive ions resulting from the repulsive environment created by core-hole Auger decay from relaxed CaF 2 surfaces. The molecular dynamics simulations in the lamina geometry (with two-dimensional ion-lattice summation) is used. For both (011) and (111) surfaces the simulation with changed charge without providing additional kinetic energy does not lead to the ejection of F + ion due to the lattice rearrangement and trapping of the ion. We also assume that the positive ion gains a substantial amount of kinetic energy at the onset of simulations, crudely mimicking ion-stimulated desorption. For the (011) surface the results are extremely sensitive to the size of the considered system, in sharp contrast to the ejection of positive ions from alkali halides. For a 384 ion system, ejection occurs if the kinetic energy, equal to 0.25 eV or more, is delivered to the F + ion at the start of the simulation. For a 768 ion system ejection occurs only for the initial kinetic energy of 4 eV. This result is probably caused by inadequate classical potential and lack of full convergence of the two-dimensional Ewald summation scheme for a highly disordered system. For the (111) surface with 1536 ions in the cell, ejection occurs for an initial kinetic energy of 0.4 eV.

  6. Calcium Carbonate.

    PubMed

    Al Omari, M M H; Rashid, I S; Qinna, N A; Jaber, A M; Badwan, A A

    2016-01-01

    Calcium carbonate is a chemical compound with the formula CaCO3 formed by three main elements: carbon, oxygen, and calcium. It is a common substance found in rocks in all parts of the world (most notably as limestone), and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. CaCO3 exists in different polymorphs, each with specific stability that depends on a diversity of variables.

  7. Calcium Carbonate.

    PubMed

    Al Omari, M M H; Rashid, I S; Qinna, N A; Jaber, A M; Badwan, A A

    2016-01-01

    Calcium carbonate is a chemical compound with the formula CaCO3 formed by three main elements: carbon, oxygen, and calcium. It is a common substance found in rocks in all parts of the world (most notably as limestone), and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. CaCO3 exists in different polymorphs, each with specific stability that depends on a diversity of variables. PMID:26940168

  8. Calcium orthophosphates

    PubMed Central

    Dorozhkin, Sergey V.

    2011-01-01

    The present overview is intended to point the readers’ attention to the important subject of calcium orthophosphates. This type of materials is of special significance for human beings, because they represent the inorganic part of major normal (bones, teeth and antlers) and pathological (i.e., those appearing due to various diseases) calcified tissues of mammals. For example, atherosclerosis results in blood vessel blockage caused by a solid composite of cholesterol with calcium orthophosphates, while dental caries and osteoporosis mean a partial decalcification of teeth and bones, respectively, that results in replacement of a less soluble and harder biological apatite by more soluble and softer calcium hydrogenphosphates. Therefore, the processes of both normal and pathological calcifications are just an in vivo crystallization of calcium orthophosphates. Similarly, dental caries and osteoporosis might be considered an in vivo dissolution of calcium orthophosphates. Thus, calcium orthophosphates hold a great significance for humankind, and in this paper, an overview on the current knowledge on this subject is provided. PMID:23507744

  9. Using Natural Stable Calcium Isotopes to Rapidly Assess Changes in Bone Mineral Balance Using a Bed Rest Model to Induce Bone Loss

    NASA Technical Reports Server (NTRS)

    Morgan, J. L. L.; Skulan, J. L.; Gordon, G. E.; Smith, Scott M.; Romaniello, S. J.; Anbar, A. D.

    2012-01-01

    Metabolic bone diseases like osteoporosis result from the disruption of normal bone mineral balance (BMB) resulting in bone loss. During spaceflight astronauts lose substantial bone. Bed rest provides an analog to simulate some of the effects of spaceflight; including bone and calcium loss and provides the opportunity to evaluate new methods to monitor BMB in healthy individuals undergoing environmentally induced-bone loss. Previous research showed that natural variations in the Ca isotope ratio occur because bone formation depletes soft tissue of light Ca isotopes while bone resorption releases that isotopically light Ca back into soft tissue (Skulan et al, 2007). Using a bed rest model, we demonstrate that the Ca isotope ratio of urine shifts in a direction consistent with bone loss after just 7 days of bed rest, long before detectable changes in bone mineral density (BMD) occur. The Ca isotope variations tracks changes observed in urinary N-teleopeptide, a bone resorption biomarker. Bone specific alkaline phosphatase, a bone formation biomarker, is unchanged. The established relationship between Ca isotopes and BMB can be used to quantitatively translate the changes in the Ca isotope ratio to changes in BMD using a simple mathematical model. This model predicts that subjects lost 0.25 0.07% ( SD) of their bone mass from day 7 to day 30 of bed rest. Given the rapid signal observed using Ca isotope measurements and the potential to quantitatively assess bone loss; this technique is well suited to study the short-term dynamics of bone metabolism.

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

    PubMed

    Jelenko, Ida; Pokorny, Boštjan

    2010-12-15

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

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

    PubMed

    Jelenko, Ida; Pokorny, Boštjan

    2010-12-15

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

  12. Modified zirconium-eriochrome cyanine R determination of fluoride

    USGS Publications Warehouse

    Thatcher, L.L.

    1957-01-01

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

  13. Efficacy of the Natural Clay, Calcium Aluminosilicate Anti-Diarrheal, in Reducing Medullary Thyroid Cancer–Related Diarrhea and Its Effects on Quality of Life: A Pilot Study

    PubMed Central

    Hu, Mimi I.; Cleeland, Charles; Busaidy, Naifa L.; Habra, Mouhammed; Waguespack, Steven G.; Sherman, Steven I.; Ying, Anita; Fox, Patricia; Cabanillas, Maria E.

    2015-01-01

    Introduction: Medullary thyroid cancer (MTC)–related diarrhea can be debilitating, reduces quality of life (QOL), and may be the only indication for initiating systemic therapy. Conventional antidiarrheal drugs are not always helpful and may have side effects. Calcium aluminosilicate antidiarrheal (CASAD), a natural calcium montmorrilonite clay, safely adsorbs toxins and inflammatory proteins associated with diarrhea. It was hypothesized that CASAD would reduce the severity of diarrhea and improve QOL in MTC patients. Methods: This was a prospective pilot trial (NCT01739634) of MTC patients not on systemic therapy with self-reported diarrhea of three or more bowel movements (BMs) per day for a week or more. The study design included a one-week run-in period followed by one week of CASAD ± a two-week optional continuation period. The primary endpoint was efficacy of one week of CASAD treatment in decreasing the number of BMs per day by ≥20% when compared with the baseline run-in period. Secondary objectives included tolerability and safety and the impact on QOL using the MD Anderson Symptom Inventory-Thyroid questionnaire (MDASI-THY). Results: Ten MTC patients (median age = 52 years, 70% female, 80% white) were enrolled. All had distant metastases, and median calcitonin was 5088 ng/mL (range 1817–42,007 ng/mL). Ninety percent had received prior antidiarrheals, and 40% of these had used two or more drugs, including tincture of opium (30%), loperamide (50%), diphenoxylate/atropine (20%), colestipol (10%), or cholestyramine (10%). Of seven evaluable patients, four (56%) had ≥20% reduction in BMs per day. Six out of seven patients discontinued their prior antidiarrheals. Best response ranged from 7% to 99% reduction in mean BMs/day from baseline. Five out of seven patients considered CASAD a success, and they opted for the two-week continuation period. Improvements in diarrhea and all six interference items assessed by MDASI-THY were noted at weeks

  14. Dietary Fluoride Intake and Associated Skeletal and Dental Fluorosis in School Age Children in Rural Ethiopian Rift Valley.

    PubMed

    Kebede, Aweke; Retta, Negussie; Abuye, Cherinet; Whiting, Susan J; Kassaw, Melkitu; Zeru, Tesfaye; Tessema, Masresha; Kjellevold, Marian

    2016-01-01

    An observational study was conducted to determine dietary fluoride intake, diet, and prevalence of dental and skeletal fluorosis of school age children in three fluorosis endemic districts of the Ethiopian Rift Valley having similar concentrations of fluoride (F) in drinking water (~5 mg F/L). The duplicate plate method was used to collect foods consumed by children over 24 h from 20 households in each community (n = 60) and the foods, along with water and beverages, were analyzed for fluoride (F) content. Prevalence of dental and skeletal fluorosis was determined using presence of clinical symptoms in children (n = 220). Daily dietary fluoride intake was at or above tolerable upper intake level (UL) of 10 mg F/day and the dietary sources (water, prepared food and beverages) all contributed to the daily fluoride burden. Urinary fluoride in children from Fentale and Adamitulu was almost twice (>5 mg/L) the concentration found in urine from children from Alaba, where rain water harvesting was most common. Severe and moderate dental fluorosis was found in Alaba and Adamitulu, the highest severity and prevalence being in the latter district where staple foods were lowest in calcium. Children in all three areas showed evidence of both skeletal and non-skeletal fluorosis. Our data support the hypothesis that intake of calcium rich foods in addition to using rain water for household consumption and preparation of food, may help in reducing risk of fluorosis in Ethiopia, but prospective studies are needed. PMID:27472351

  15. Dietary Fluoride Intake and Associated Skeletal and Dental Fluorosis in School Age Children in Rural Ethiopian Rift Valley

    PubMed Central

    Kebede, Aweke; Retta, Negussie; Abuye, Cherinet; Whiting, Susan J.; Kassaw, Melkitu; Zeru, Tesfaye; Tessema, Masresha; Kjellevold, Marian

    2016-01-01

    An observational study was conducted to determine dietary fluoride intake, diet, and prevalence of dental and skeletal fluorosis of school age children in three fluorosis endemic districts of the Ethiopian Rift Valley having similar concentrations of fluoride (F) in drinking water (~5 mg F/L). The duplicate plate method was used to collect foods consumed by children over 24 h from 20 households in each community (n = 60) and the foods, along with water and beverages, were analyzed for fluoride (F) content. Prevalence of dental and skeletal fluorosis was determined using presence of clinical symptoms in children (n = 220). Daily dietary fluoride intake was at or above tolerable upper intake level (UL) of 10 mg F/day and the dietary sources (water, prepared food and beverages) all contributed to the daily fluoride burden. Urinary fluoride in children from Fentale and Adamitulu was almost twice (>5 mg/L) the concentration found in urine from children from Alaba, where rain water harvesting was most common. Severe and moderate dental fluorosis was found in Alaba and Adamitulu, the highest severity and prevalence being in the latter district where staple foods were lowest in calcium. Children in all three areas showed evidence of both skeletal and non-skeletal fluorosis. Our data support the hypothesis that intake of calcium rich foods in addition to using rain water for household consumption and preparation of food, may help in reducing risk of fluorosis in Ethiopia, but prospective studies are needed. PMID:27472351

  16. Dietary Fluoride Intake and Associated Skeletal and Dental Fluorosis in School Age Children in Rural Ethiopian Rift Valley.

    PubMed

    Kebede, Aweke; Retta, Negussie; Abuye, Cherinet; Whiting, Susan J; Kassaw, Melkitu; Zeru, Tesfaye; Tessema, Masresha; Kjellevold, Marian

    2016-07-26

    An observational study was conducted to determine dietary fluoride intake, diet, and prevalence of dental and skeletal fluorosis of school age children in three fluorosis endemic districts of the Ethiopian Rift Valley having similar concentrations of fluoride (F) in drinking water (~5 mg F/L). The duplicate plate method was used to collect foods consumed by children over 24 h from 20 households in each community (n = 60) and the foods, along with water and beverages, were analyzed for fluoride (F) content. Prevalence of dental and skeletal fluorosis was determined using presence of clinical symptoms in children (n = 220). Daily dietary fluoride intake was at or above tolerable upper intake level (UL) of 10 mg F/day and the dietary sources (water, prepared food and beverages) all contributed to the daily fluoride burden. Urinary fluoride in children from Fentale and Adamitulu was almost twice (>5 mg/L) the concentration found in urine from children from Alaba, where rain water harvesting was most common. Severe and moderate dental fluorosis was found in Alaba and Adamitulu, the highest severity and prevalence being in the latter district where staple foods were lowest in calcium. Children in all three areas showed evidence of both skeletal and non-skeletal fluorosis. Our data support the hypothesis that intake of calcium rich foods in addition to using rain water for household consumption and preparation of food, may help in reducing risk of fluorosis in Ethiopia, but prospective studies are needed.

  17. High-fluoride groundwater.

    PubMed

    Rao, N Subba

    2011-05-01

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

  18. [Adsorption of fluoride ions on a Ca-deficient hydroxyapatite].

    PubMed

    Li, Ling; Zhu, Zhi-Liang; Qiu, Yan-Ling; Zhang, Hua; Zhao, Jian-Fu

    2010-06-01

    A Ca-deficient hydroxyapatite (d-HAp) from the by-product of phosphate wastewater treatment has been used to remove fluoride ions. The effects of pH, coexistent calcium and magnesium ions, and chloride ions on the adsorption efficiency were investigated for the system. The results showed that d-HAp adsorbed F- efficiently within a wide pH range (4-7), and the defluoridation capacity of d-HAp remained 85%. There was no significant effect on removal of fluoride ions with addition of up to 200 times as high a concentration of Ca2+, Mg2+ and Cl-, so it suggested that d-HAp was applicable to high fluoride area. The adsorption kinetics can be described by Pseudo-second-order reaction model and the correlation coefficient R2 was 0.999 0. It was also found that the adsorption of F- on d-HAp followed the Langmuir model. The maximal static adsorption capacity was calculated as 26.11 mg x g(-1). It also suggested that ion exchange was the main mechanism during this adsorptive process. PMID:20698272

  19. Intergranular fracture of lithium fluoride-22 percent calcium fluoride hypereutectic salt at 800 K

    NASA Technical Reports Server (NTRS)

    Raj, Subramanium V.; Whittenberger, J. Daniel

    1990-01-01

    Substantial strain-hardening was noted during the initial stages of deformation in constant-velocity compression tests conducted on as-cast samples of the LiF-22 mol pct CaF2 hypereutectic salt at 800 K. The deformed specimens exhibited extensive grain-boundary cracking and cavitation, suggesting that such cracking, in conjunction with interfacial sliding, is important for cavity nucleation at grain boundaries and at the LiF-CaF2 interfaces. Cavity growth and interlinkage occur through the preferential failure of the weaker LiF phase.

  20. Anhydrous hydrogen fluoride electrolyte battery. [Patent application

    DOEpatents

    Not Available

    1972-06-26

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

  1. The Effect of Fluoride in Osteoporosis.

    ERIC Educational Resources Information Center

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

    1987-01-01

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

  2. A Manual for Rural School Fluoridation.

    ERIC Educational Resources Information Center

    Sprouse, Larman W.; Brooks, John

    The product of a 1972 Dental Health Branch contract with the U.S. Public Health Service, this manual is designed to aid in the development of school fluoridation programs and presents: background information on general concepts relating to the action of fluoride on teeth; discussions dealing with community and school fluoridation studies; and the…

  3. Cytosolic calcium signals elicited by the pathogen-associated molecular pattern flg22 in stomatal guard cells are of an oscillatory nature.

    PubMed

    Thor, Kathrin; Peiter, Edgar

    2014-12-01

    Changes in cytosolic free calcium ([Ca(2+)]cyt) are an early and essential element of signalling networks activated by the perception of pathogen-associated molecular patterns (PAMPs), such as flg22. The flg22-induced calcium signal has been described on whole-plant, but not on single-cell scale so far. Also, the Ca(2+) sources and channels contributing to its generation are still obscure. Ratiometric fluorescence imaging employing the calcium reporter Yellow Cameleon 3.6 was performed to analyse the flg22-induced calcium signature in single guard cells of Arabidopsis thaliana. Calcium stores and channel types involved in its generation were determined by a pharmacological approach. In contrast to the calcium signal determined on whole-plant level, the signature on single-cell level is not characterized by one sustained response, but by oscillations in [Ca(2+)]cyt. These oscillations were abolished by EGTA and lanthanum, as well as by U73122, neomycin and TMB-8, but only partially or not at all affected by inhibitors of glutamate receptor-like channels and cyclic nucleotide-gated channels. Our analyses suggest that the response observed on whole-plant level is the summary of oscillations occurring in single cells. Parallel to external calcium, influx via channels located at internal stores contributes to the signal.

  4. METHOD OF PREPARING METAL FLUORIDES

    DOEpatents

    Katz, J.J.; Sheft, I.

    1959-08-11

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

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Increased ash contents and estimation of dissolution from chemical changes due to in-vitro fluoride treatments.

    PubMed

    Kotha, S P; DePaula, C A; Koike, K; Pan, Y; Ohno, M; Abjornson, C; Rangarajan, S; Guzelsu, N

    2002-01-01

    The in-vitro fluoride treatment technique has been introduced to investigate the composite behavior of bone tissue. Bone tissue with different mechanical properties can be obtained by varying the concentration, pH and immersion time in fluoride ion solutions. The chemical and physical changes in intact pieces of bone treated in-vitro with different concentrations of fluoride ions are studied. The amount of bone mineral that does not contribute to the mechanical behavior of bone tissue is estimated from the dissolution occurring in the fluoride treated bones. Cortical bones from 18-month-old steers were treated in-vitro with 0.145, 0.5 and 2.0 M sodium fluoride (NaF) solutions for three days. The dissolved bone mineral precipitates as calcium fluoride-like (CaF2/P with some phosphate [P] ions) and fluorapatite(FAp)/fluorhydroxyapatite(FHAp)-like materials within the bone tissue. The dissolution estimated from the presence of the precipitated fluoride phases is 5.6, 11.7, and 13.1% of the initial bone mineral content for the 0.145 M, 0.5 M, and 2.0 M NaF treatments respectively. Estimates of dissolution based on the measurements of phosphate and carbonate ions are lower and higher respectively when compared to the fluoride ion measurements. The wet and dry densities decreased slightly due to dissolution and re-precipitation while the ash content (ratio of the ash weight to dry weight) increased a small amount with increasing concentration of fluoride ion treatments. The increased ash content was due to the excess loss of water in the fluoride treated bones as compare to controls (untreated bone samples) during the drying process. The increased removal of water during the drying process may explain the increased ash contents in some in-vivo treatments.

  7. A preliminary investigation of lithogenic and anthropogenic influence over fluoride ion chemistry in the groundwater of the southern coastal city, Tamilnadu, India.

    PubMed

    Selvam, S

    2015-03-01

    A total of 72 groundwater samples were collected from open wells and boreholes during pre- and post-monsoon periods in Tuticorin. Samples were analyzed for physicochemical properties, major cations, and anions in the laboratory using the standard methods given by the American Public Health Association. The fluoride concentration was analyzed in the laboratory using Metrohm 861 advanced compact ion chromatography. The geographic information system-based spatial distribution map of different major elements has been prepared using ArcGIS 9.3. The fluoride concentration ranges between 0.16 mg/l and 4.8 mg/l during pre-monsoon and 0.2-3.2 mg/l during post-monsoon. Alkaline pH, low calcium concentrations, high groundwater temperatures, and semiarid climatic conditions of the study area may cause elevated fluoride concentrations in groundwater, by increasing the solubility of fluoride-bearing formations (fluoride). Linear trend analysis on seasonal and annual basis clearly depicted that fluoride pollution in the study area is increasing significantly. Fluoride concentrations showed positive correlations with those of Na(+) and HCO3 (-) and negative correlations with Ca(2+) and Mg(2+). The alkaline waters were saturated with calcite in spite of the low Ca(2+) concentrations. Northwestern parts of the study area are inherently enriched with fluorides threatening several ecosystems. The saturation index indicates that dissolution and precipitation contribute fluoride dissolution along with mixing apart from anthropogenic activities. PMID:25666649

  8. A preliminary investigation of lithogenic and anthropogenic influence over fluoride ion chemistry in the groundwater of the southern coastal city, Tamilnadu, India.

    PubMed

    Selvam, S

    2015-03-01

    A total of 72 groundwater samples were collected from open wells and boreholes during pre- and post-monsoon periods in Tuticorin. Samples were analyzed for physicochemical properties, major cations, and anions in the laboratory using the standard methods given by the American Public Health Association. The fluoride concentration was analyzed in the laboratory using Metrohm 861 advanced compact ion chromatography. The geographic information system-based spatial distribution map of different major elements has been prepared using ArcGIS 9.3. The fluoride concentration ranges between 0.16 mg/l and 4.8 mg/l during pre-monsoon and 0.2-3.2 mg/l during post-monsoon. Alkaline pH, low calcium concentrations, high groundwater temperatures, and semiarid climatic conditions of the study area may cause elevated fluoride concentrations in groundwater, by increasing the solubility of fluoride-bearing formations (fluoride). Linear trend analysis on seasonal and annual basis clearly depicted that fluoride pollution in the study area is increasing significantly. Fluoride concentrations showed positive correlations with those of Na(+) and HCO3 (-) and negative correlations with Ca(2+) and Mg(2+). The alkaline waters were saturated with calcite in spite of the low Ca(2+) concentrations. Northwestern parts of the study area are inherently enriched with fluorides threatening several ecosystems. The saturation index indicates that dissolution and precipitation contribute fluoride dissolution along with mixing apart from anthropogenic activities.

  9. Fluoride uptake from in situ brushing with a SnF2 and a NaF dentifrice.

    PubMed

    Mobley, M J

    1981-12-01

    Fluoride uptake into decalcified human enamel was determined from in situ brushing with a 0.40% SnF2-calcium pyrophosphate abrasive dentifrice, a 0.243% NaF-silica abrasive dentifrice, and a non-fluoride-silica abrasive placebo dentifrice. Dentifrice treatments were compared using a randomized block test design with 11 panelists, wearing specially fabricated partial dentures that were able to hold two 3-mm-diameter enamel discs in proximal positions. The enamel discs were analyzed for fluoride after two wk of regular use of the test dentifrices. The mean fluoride contents after use of the test dentifrices were 16.0, 8.4, and 4.6 micro/cm2 for the 0.243% NaF, the 0.40% SnF2, and the placebo dentifrice, respectively. The differences in the means were statistically significant. These uptake results correlate well with the reported clinical efficacies of these dentifrices.

  10. Potable groundwater quality in some villages of Haryana, India: focus on fluoride.

    PubMed

    Bishnoi, Mukul; Arora, Shalu

    2007-04-01

    The fluoride concentration in ground water was determined in ten villages of Rohtak district of Haryana state (India). The fluoride concentration in the underground water of these villages varied from 0.034-2.09 mg/l. Various other water quality parameters, viz., pH, electrical conductivity, total dissolved salts, total hardness, total alkalinity sodium, potassium, calcium, magnesium, carbonate, bicarbonate, chloride and sulfate were also measured. A systematic calculation of correlation coefficients among different physicochemical parameters indicated considerable variations among the analyzed samples with respect to their chemical composition. Majority of the samples do not comply with Indian as well as WHO standards for most of the water quality parameters measured. Overall water quality was found unsatisfactory for drinking purposes. Fluoride content was higher than permissible limit in 50% samples.

  11. Fluoride in chilies from southwestern china.

    PubMed

    Li, Bo; Li, Shehong; Wang, Mingguo; Liu, Xiaojing; Zheng, Baoshan

    2008-10-01

    The purpose of this research is to investigate the fluoride contents in the chilies from southwest China and other countries in order to calculate the difference in fluoride levels in the fresh chilies. The standard method in China for analysis of fluoride in food (GB/T 5009.18-2003) was applied to determinate the fluoride content in chilies. By determining the fluoride content in 176 fresh chili samples from 77 counties in southwest China and 31 chili samples from other countries, the research not only aims to find the regularity of fluoride distribution in fresh chili, but also to determine the origin of fluoride in fresh chili in China compared with the foreign samples. The geometric mean of fluoride content in the fresh chili was 8.9 mg kg(-1) (dry weight, 176 samples, confidence level: 95%). According to the study on the contents of fluoride in fresh chili, it seems that the fluoride content standard for vegetables in GB2762-2005 in China is inappropriate for chili, and 24.7 mg kg(-1)(dry weight) and 5.2 mg kg(-1) (fresh weight) in recommend as the fluoride contaminated discrimination values for fresh chili.

  12. Comparison of the antimicrobial efficacy of chlorhexidine, sodium fluoride, fluoride with essential oils, alum, green tea, and garlic with lime mouth rinses on cariogenic microbes

    PubMed Central

    Thomas, Ann; Thakur, Sneha; Mhambrey, Sanjana

    2015-01-01

    Background: A number of natural mouth rinse formulations are being proposed as an alternative to the widely used chemical mouth rinses. Objective: To evaluate and compare the antimicrobial efficacy of chlorhexidine (0.2%), sodium fluoride (0.05%), fluoride with essential oils (0.05%), alum (0.02 M), green tea, and garlic with lime mouth rinses against Streptococcus mutans, lactobacilli, and Candida albicans. Materials and Methods: The three microbes were isolated from the saliva samples collected from children with severe early childhood caries. The zone of minimum inhibition was assessed using agar diffusion method. The data were statistically analyzed using SPSS software. Results: Against S. mutans and lactobacilli, chlorhexidine mouth rinse was found to be the most effective as compared to sodium fluoride (P < 0.001, P < 0.001), fluoride with essential oils (P < 0.001, P < 0.001), alum (P < 0.001, P < 0.001), green tea (P < 0.001, P < 0.001), and garlic with lime (P < 0.001, P < 0.001) mouth rinses, respectively. But against C. albicans, garlic with lime mouth rinse was found to be the most effective as compared to chlorhexidine (P < 0.001), sodium fluoride (P < 0.001), fluoride with essential oils (P < 0.001), alum (P < 0.001), and green tea (P < 0.001) mouth rinses. Against S. mutans and lactobacilli, after chlorhexidine mouth rinse, garlic with lime mouth rinse was found to be significantly more effective than sodium fluoride (P = 0.053, P = 0.001), fluoride with essential oils (P < 0.001, P < 0.001), alum (P < 0.001, P < 0.001), and green tea (P < 0.001, P < 0.001) mouth rinses. Conclusion: As a natural mouth rinse, garlic with lime mouth rinse was found to be the most promising. However, further studies are needed in this field. PMID:26312230

  13. Salt fluoridation in Germany since 1991.

    PubMed

    Schulte, Andreas G

    2005-01-01

    Since 1991, fluoridated salt has been on sale in household-size packages in Germany. Potassium or sodium fluoride is added to iodized salt until the fluoride concentration reaches 250 mg/kg. The use of fluoridated salt to prevent caries is officially recommended by the Deutsche Gesellschaft für Zahn-, Mund- und Kieferheilkunde (DGZMK) and several other associations and groups interested in public health. In the course of the past thirteen years, the market share of fluoridated and iodized domestic salt rose to 63.1% in Germany. However, this positive development must not obscure the fact that fluoridated and iodized salt is still not allowed to be used in restaurant or cafeteria kitchens. This restriction now needs to be revoked in view of the fact that many children, adolescents and adults take their main meals in cafeterias or restaurants. Scientific studies have demonstrated beyond doubt that using fluoridated and iodized salt in cafeteria kitchens poses no problem whatever.

  14. The role of fluoride in erosion therapy.

    PubMed

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

    2014-01-01

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

  15. Special Report: Fluoridation of Water.

    ERIC Educational Resources Information Center

    Hileman, Bette

    1988-01-01

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

  16. [Fluoride accumulation and distribution in mulberry insects near fluoride pollution sources].

    PubMed

    Chen, Yuyin; Lu, Shenggao

    2002-01-01

    Fluoride accumulation and the relative fluoride loading of different body parts in wild mulberry silkworm (Bombyx mandarina M.), mulberry geometrid (Pathonandria atrineata B.), and mulberry silkworm (Bombyx mori L.) near fluoride pollution sources were studied. Comparison of the fluoride content of insect bodies and mulberry leaves showed that insects collected from polluted sites had increased fluoride accumulation. The digestive tract of the insect had much higher fluoride content than the other parts of the body and was considered to be the important organ of fluoride accumulation. There were also wide differences in fluoride accumulation between different insect species within the same polluted site. The highly significantly correlation between fluoride contents of wild mulberry silkworm, mulberry geometrid, and mulberry silkworm with that of the mulberry leaves on which they were collected was found.

  17. The effect of fluoridation and its discontinuation on fluoride profiles in the alveolar bone of rat.

    PubMed

    Ohmi, Kyohei; Nakagaki, Haruo; Tsuboi, Shinji; Okumura, Akihiro; Sugiyama, Tomoko; Thuy, Tran Thu; Robinson, Colin

    2005-10-01

    We investigated the effect of fluoridation and its discontinuation on fluoride content in the alveolar portion of the mandible in rats. Drinking water with three different fluoride contents (0, 50, 100 ppmF) was given to rats for three different periods (4, 13 and 25 weeks). Fluoride concentrations were measured in the crest, the middle, and the apical parts of the alveolar bone and in the body of the mandible. Furthermore, after fluoridated drinking water was given to rats for 4 or 13 weeks, distilled water was given to them for 21 or 12 weeks respectively; and the effect of the discontinuation on fluoride profiles was investigated. Layer samples were analyzed by abrasive microsampling. Fluoride and phosphorus concentrations were determined by ion-specific electrode and colorimetric procedures, respectively. There was an increase in fluoride concentrations in the mandible in proportion to the fluoride content in the drinking water and the duration of fluoridation. After fluoridation was discontinued, fluoride concentrations in the surface layers of the mandible presented a decrease. Among the four different parts of the mandible, the upper part of the alveolar bone and the alveolar crest part presented the highest rates of reduction. The relative reduction rate of fluoride concentration was closely related to the duration of discontinuation. The alveolar crest was affected most by the discontinuation of fluoridation, presenting the greatest reduction.

  18. Get Enough Calcium

    MedlinePlus

    ... Calcium Print This Topic En español Get Enough Calcium Browse Sections The Basics Overview Foods and Vitamins ... 2 of 4 sections Take Action! Take Action: Calcium Sources Protect your bones – get plenty of calcium ...

  19. Calcium carbonate overdose

    MedlinePlus

    Tums overdose; Calcium overdose ... Calcium carbonate can be dangerous in large amounts. ... Some products that contain calcium carbonate are certain: ... and mineral supplements Other products may also contain calcium ...

  20. Calcium cyanide

    Integrated Risk Information System (IRIS)

    Jump to main content . Integrated Risk Information System Recent Additions | Contact Us Search : All EPA IRIS • You are here : EPA Home • Research • Environmental Assessment • IRIS • IRIS Summaries Redirect Page As of September 28 , 2010 , the assessment summary for calcium cyanide is included in th

  1. Alimentary fluoride intake in preschool children

    PubMed Central

    2011-01-01

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

  2. Determining the optimal fluoride concentration in drinking water for fluoride endemic regions in South India.

    PubMed

    Viswanathan, Gopalan; Jaswanth, A; Gopalakrishnan, S; Siva Ilango, S; Aditya, G

    2009-10-01

    Fluoride ion in drinking water is known for both beneficial and detrimental effects on health. The prevalence of fluorosis is mainly due to the intake of large quantities of fluoride through drinking water owing to more than 90% bioavailability. The objective of this study is to predict optimal fluoride level in drinking water for fluoride endemic regions by comprising the levels of fluoride and other water quality parameters in drinking water, prevalence of fluorosis, fluoride intake through water, food and beverages such as tea and coffee and also considering the progressive accumulation of fluoride in animal bones, by comparing with non fluoride endemic areas comprise of the same geological features with the aid of regression analysis. Result of this study shows that increase of fluoride level above 1.33 mg/l in drinking water increases the community fluorosis index (CFI) value more than 0.6, an optimum index value above which fluorosis is considered to be a public health problem. Regression plot between water fluoride and bone fluoride levels indicates that, every increase of 0.5mg/l unit of water fluoride level increases the bone fluoride level of 52 mg/kg unit within 2 to 3 years. Furthermore, the consumption of drinking water containing more than 0.65 mg/l of fluoride can raise the total fluoride intake per day more than 4 mg, which is the optimum fluoride dose level recommended for adults by the Agency for Toxic Substances and Disease Registry. From the result, the people in fluoride endemic areas in South India are advised to consume drinking water with fluoride level within the limit of 0.5 to 0.65 mg/l to avoid further fluorosis risk.

  3. Global affordability of fluoride toothpaste

    PubMed Central

    Goldman, Ann S; Yee, Robert; Holmgren, Christopher J; Benzian, Habib

    2008-01-01

    Objective Dental caries remains the most common disease worldwide and the use of fluoride toothpaste is a most effective preventive public health measure to prevent it. Changes in diets following globalization contribute to the development of dental caries in emerging economies. The aim of this paper is to compare the cost and relative affordability of fluoride toothpaste in high-, middle- and low-income countries. The hypothesis is that fluoride toothpaste is not equally affordable in high-, middle- and low-income countries. Methods Data on consumer prices of fluoride toothpastes were obtained from a self-completion questionnaire from 48 countries. The cost of fluoride toothpaste in high-, middle- and low-income countries was compared and related to annual household expenditure as well as to days of work needed to purchase the average annual usage of toothpaste per head. Results The general trend seems to be that the proportion of household expenditure required to purchase the annual dosage of toothpaste increases as the country's per capita household expenditure decreases. While in the UK for the poorest 30% of the population only 0.037 days of household expenditure is needed to purchase the annual average dosage (182.5 g) of the lowest cost toothpaste, 10.75 days are needed in Kenya. The proportion of annual household expenditure ranged from 0.02% in the UK to 4% in Zambia to buy the annual average amount of lowest cost toothpaste per head. Conclusion Significant inequalities in the affordability of this essential preventive care product indicate the necessity for action to make it more affordable. Various measures to improve affordability based on experiences from essential pharmaceuticals are proposed. PMID:18554382

  4. Anomalous distribution of fluoride and phosphorus forms in surface sediments along eastern Egyptian Mediterranean Sea coast.

    PubMed

    El-Said, Ghada F; Khalil, Mona Kh; Draz, Suzanne E O

    2016-07-01

    The study focused on the distribution of fluoride, total phosphorus, and four phosphorus fractions in some sites along the Egyptian Mediterranean Sea coast. The geochemical parameters and textures of 30 surficial sediment samples from six sectors were determined. The sediment's geochemical parameters (total carbonates (TCO3) and total organic carbon (TOC), exchangeable and carbonate-associated phosphorus (Pex), iron- and aluminum-associated phosphorus (POH), calcium-associated phosphate/apatite (PHCl), residual phosphorus (PR), total phosphorus (TP), calcium (Cas), magnesium (Mgs), and fluoride (Fs)) showed variable values. The rank of phosphorus fractions in the sediments PHCl > PR > POH > Pex reflected that the eastern Egyptian coast was still uncontaminated. Generally, Pex levels gave a gradual increase in the offshore direction, while POH values varied along the stations of each sector. Also, the presented data indicated that the apatite-P fraction was the main storage of the phosphate in the sediments with a contribution to TP ranging from 58 to 87 %. The highest and lowest average fluoride contents (0.49 ± 0.10 and 0.25 ± 0.31 mg/g) were determined in the Port Said and Damietta sectors, respectively. Interestingly, the variability of both phosphorus and fluoride levels in the investigated area seemed to be accompanied with the sediment's character beside the proximity to potential effluent sources. PMID:27053053

  5. Anomalous distribution of fluoride and phosphorus forms in surface sediments along eastern Egyptian Mediterranean Sea coast.

    PubMed

    El-Said, Ghada F; Khalil, Mona Kh; Draz, Suzanne E O

    2016-07-01

    The study focused on the distribution of fluoride, total phosphorus, and four phosphorus fractions in some sites along the Egyptian Mediterranean Sea coast. The geochemical parameters and textures of 30 surficial sediment samples from six sectors were determined. The sediment's geochemical parameters (total carbonates (TCO3) and total organic carbon (TOC), exchangeable and carbonate-associated phosphorus (Pex), iron- and aluminum-associated phosphorus (POH), calcium-associated phosphate/apatite (PHCl), residual phosphorus (PR), total phosphorus (TP), calcium (Cas), magnesium (Mgs), and fluoride (Fs)) showed variable values. The rank of phosphorus fractions in the sediments PHCl > PR > POH > Pex reflected that the eastern Egyptian coast was still uncontaminated. Generally, Pex levels gave a gradual increase in the offshore direction, while POH values varied along the stations of each sector. Also, the presented data indicated that the apatite-P fraction was the main storage of the phosphate in the sediments with a contribution to TP ranging from 58 to 87 %. The highest and lowest average fluoride contents (0.49 ± 0.10 and 0.25 ± 0.31 mg/g) were determined in the Port Said and Damietta sectors, respectively. Interestingly, the variability of both phosphorus and fluoride levels in the investigated area seemed to be accompanied with the sediment's character beside the proximity to potential effluent sources.

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

    PubMed Central

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

    2016-01-01

    It was the aim of this study to investigate differences in fluoride bioavailability in different oral areas after the application of amine fluoride (AmF) and sodium fluoride (NaF). The null hypothesis suggested no differences in the fluoride bioavailability. The tongue coating was removed and biofilm samples from the palate, oral floor and cheeks were collected. All subjects brushed their teeth with toothpaste containing AmF or NaF. Specimens were collected before, as well as immediately after and at 30 and 120 minutes after tooth brushing. The fluoride concentration was determined. The area under the curve was calculated for each location and compared statistically. In the tongue coating, fluoride concentration increased faster after NaF application than after AmF application. After 30 minutes, the fluoride concentration decreased and remained stable until 120 minutes after AmF application and returned to baseline after NaF application. The difference between the baseline and the endpoint measurements was statistically significant. The fluoride concentration in the tongue coating remained at a higher level compared with the baseline for up to 120 minutes post-brushing. This may indicate that the tongue coating is a major reservoir for fluoride bioavailability. The results also indicate an unequal fluoride distribution in the oral cavity. PMID:26727989

  7. Changes in mesophyll element distribution and phytometabolite contents involved in fluoride tolerance of the arid gypsum-tolerant plant species Atractylis serratuloides Sieber ex Cass. (Asteraceae).

    PubMed

    Boukhris, Asma; Laffont-Schwob, Isabelle; Rabier, Jacques; Salducci, Marie-Dominique; El Kadri, Lefi; Tonetto, Alain; Tatoni, Thierry; Chaieb, Mohamed

    2015-05-01

    Atractylis serratuloides is an abundant native spiny species that grows in the surroundings of superphosphate factories in Tunisia. This plant species is adapted to arid environments and tolerates a high level of fluoride pollution in soils. The aim of this study was to better understand the physiological mechanisms of fluoride tolerance of this species, comparing the fluoride-contaminated sites of Gabes and Skhira with the reference site of Smara. Results demonstrated the involvement of leaf element and phytometabolite balances in the in situ response of A. serrulatoides to fluoride. Calcium, sulphur and magnesium were differently distributed between the sites of Gabes and Smara in all plant organs. No specific tissue fluorine accumulation in root, stem and leaf, even in the most contaminated site at Gabes, was detected by EDAX mapping. Lower anthocyan and flavonol levels but enhanced nitrogen balance index were found in A. serrulatoides leaves from Gabes compared to the two other sites. A. serratuloides appeared as a fluoride excluder and its tolerance involved calcium interactions with fluoride. Moreover, an occurrence of dark septate endophytes and arbuscular mycorhizal fungi in root systems of A. serratuloides was reported for the first time, and these symbioses were present but low at all sites. We suggest the use of this plant species for fluoride-polluted soil stabilization. PMID:25510616

  8. Changes in mesophyll element distribution and phytometabolite contents involved in fluoride tolerance of the arid gypsum-tolerant plant species Atractylis serratuloides Sieber ex Cass. (Asteraceae).

    PubMed

    Boukhris, Asma; Laffont-Schwob, Isabelle; Rabier, Jacques; Salducci, Marie-Dominique; El Kadri, Lefi; Tonetto, Alain; Tatoni, Thierry; Chaieb, Mohamed

    2015-05-01

    Atractylis serratuloides is an abundant native spiny species that grows in the surroundings of superphosphate factories in Tunisia. This plant species is adapted to arid environments and tolerates a high level of fluoride pollution in soils. The aim of this study was to better understand the physiological mechanisms of fluoride tolerance of this species, comparing the fluoride-contaminated sites of Gabes and Skhira with the reference site of Smara. Results demonstrated the involvement of leaf element and phytometabolite balances in the in situ response of A. serrulatoides to fluoride. Calcium, sulphur and magnesium were differently distributed between the sites of Gabes and Smara in all plant organs. No specific tissue fluorine accumulation in root, stem and leaf, even in the most contaminated site at Gabes, was detected by EDAX mapping. Lower anthocyan and flavonol levels but enhanced nitrogen balance index were found in A. serrulatoides leaves from Gabes compared to the two other sites. A. serratuloides appeared as a fluoride excluder and its tolerance involved calcium interactions with fluoride. Moreover, an occurrence of dark septate endophytes and arbuscular mycorhizal fungi in root systems of A. serratuloides was reported for the first time, and these symbioses were present but low at all sites. We suggest the use of this plant species for fluoride-polluted soil stabilization.

  9. Fluoride incidence in groundwater: a case study from Talupula, Andhra Pradesh, India.

    PubMed

    Arveti, Nagaraju; Sarma, M R S; Aitkenhead-Peterson, J A; Sunil, K

    2011-01-01

    Fluoride-rich groundwater is well known in granite aquifers in India and the world. This study examines the fluoride content of well water in different parts of Talupula area of Anantapur district, Andhra Pradesh. It also focuses on fluorides and their relationship to water-quality parameters and their impacts on humans through groundwater resources. Most parts of the area covered in this region are inherently enriched with fluorides threatening several ecosystems. The fluoride concentration ranges between 0.78 and 6.10 mg L⁻¹. The alkaline pH and high bicarbonate are responsible for release of fluoride-bearing minerals into groundwater. The arid climate of the region, the granitic rocks and the low freshwater exchange due to periodical drought conditions are the factors responsible for the higher incidence of fluorides in the groundwater resources. Apart from these prevailing natural conditions, years of neglect and lack of restoration programs on terrestrial and aquatic environments have led to accumulative impacts on groundwater, soils, plants, and animals including humans. The people dependent on these groundwater resources are prone to dental fluorosis and mild skeletal fluorosis.

  10. Fluoride incidence in groundwater: a case study from Talupula, Andhra Pradesh, India.

    PubMed

    Arveti, Nagaraju; Sarma, M R S; Aitkenhead-Peterson, J A; Sunil, K

    2011-01-01

    Fluoride-rich groundwater is well known in granite aquifers in India and the world. This study examines the fluoride content of well water in different parts of Talupula area of Anantapur district, Andhra Pradesh. It also focuses on fluorides and their relationship to water-quality parameters and their impacts on humans through groundwater resources. Most parts of the area covered in this region are inherently enriched with fluorides threatening several ecosystems. The fluoride concentration ranges between 0.78 and 6.10 mg L⁻¹. The alkaline pH and high bicarbonate are responsible for release of fluoride-bearing minerals into groundwater. The arid climate of the region, the granitic rocks and the low freshwater exchange due to periodical drought conditions are the factors responsible for the higher incidence of fluorides in the groundwater resources. Apart from these prevailing natural conditions, years of neglect and lack of restoration programs on terrestrial and aquatic environments have led to accumulative impacts on groundwater, soils, plants, and animals including humans. The people dependent on these groundwater resources are prone to dental fluorosis and mild skeletal fluorosis. PMID:20140498

  11. Design, synthesis, and optimization of nanostructured calcium phosphates (NanoCaPs) and natural polymer based 3-D non-viral gene delivery systems

    NASA Astrophysics Data System (ADS)

    Ko, Hsu-Feng

    Sustained delivery of therapeutic genes from a three-dimensional (3-D) scaffold and subsequent gene expression capable of triggering the regeneration of damaged tissues is a tissue engineering strategy that has been gaining increased attention. Nanostructured calcium phosphates (NanoCaPs) are biocompatible and non-toxic biomaterials. Furthermore, their efficient transfection in vitro have rendered them attractive gene delivery carriers compared to other viral- or lipid-based agents that tend to be immunogenic or cytotoxic, leading to undesirable responses when utilized above a critical threshold. However, NanoCaPs are typically characterized by variable transfection and short shelf life due to particle aggregation. A viable solution to this problem is the incorporation of NanoCaPs into 3-D scaffolds. The main objectives of this research are therefore two-fold: (1) Examination of the potential of achieving optimized transfection of NanoCaPs via anionic substitution and (2) high throughput synthesis and screening of non-viral gene delivery systems (GDS) comprised of naturally-derived polymers as scaffolds containing NanoCaPs gene carriers. Results indicated that in addition to the excellent transfection levels exhibited by NanoCaPs in vitro, an additional 20-30% increase was observed for NanoCaPs with 10-25 mol% anion substitution. In contrast, high anion substitution (>60%) yielded a drastic decline in transfection. Structural characterizations verified successful anion substitution with a noticeable increase in lattice parameters indicative of an expanded unit cell due to ionic substitution. All of the anion substituted calcium phosphates exhibited the primary phase of hydroxyapatite. For the first time, GDS composed of various concentrations of alginate (AA), fibronectin (FN), and NanoCaPs-DNA complexes were demonstrated. The presence of AA and FN was effective in immobilizing NanoCaPs and reducing the aggregation. High throughput synthesis and screening

  12. Stability against brushing abrasion and the erosion-protective effect of different fluoride compounds.

    PubMed

    Wiegand, A; Schneider, S; Sener, B; Roos, M; Attin, T

    2014-01-01

    This study aimed to analyse the impact of brushing on the protective effect of different fluoride solutions on enamel and dentin erosion. Bovine enamel and dentin specimens were rinsed once with TiF4, AmF, SnF2 (0.5 M F, 2 min) or water (control). Specimens were either left unbrushed or brushed with 10, 20, 50, 100 or 500 brushing strokes in an automatic brushing machine (2 N, non-fluoridated toothpaste slurry). Ten specimens per group were eroded with hydrochloric acid (HCl) (pH 2.3) for 60 s, and calcium release into the acid was determined by atomic absorption spectroscopy. Additionally, enamel and dentin surfaces were analysed by X-ray energy-dispersive spectroscopy (EDS) (n = 6/group) and scanning electron microscopy (SEM) (n = 2/group) before brushing and after 500 brushing strokes. Statistical analysis (p < 0.05) was performed by three- and one-way ANOVA (calcium release) or repeated measures ANOVA (EDS). TiF4, AmF and SnF2 reduced the erosive calcium loss in unbrushed specimens to 58-67% (enamel) and 23-31% (dentin) of control. Calcium release increased with increasing brushing strokes prior to erosion and amounted to 70-88% (enamel) and 45-78% (dentin) of control after 500 brushing strokes. Brushing reduced the surface concentration of fluoride (AmF), tin (SnF2) and titanium (TiF4). SEM revealed that surface precipitates were affected by long-term brushing. Brushing reduced the protective potential of TiF4, AmF and SnF2 solutions. However, considering a small number of brushing strokes, the protective effect of fluoride solutions is only slightly affected by brushing abrasion.

  13. 21 CFR 177.2510 - Polyvinylidene fluoride resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Polyvinylidene fluoride resins. 177.2510 Section... Repeated Use § 177.2510 Polyvinylidene fluoride resins. Polyvinylidene fluoride resins may be safely used... fluoride resins consist of basic resins produced by the polymerization of vinylidene fluoride. (b)...

  14. [Alternative ways of fluoride supplementation in childhood (author's transl)].

    PubMed

    Bergmann, K E; Bergmann, R L

    1977-02-01

    Fluorine is a nutritionally essential trace element. Fluoride concentration in drinking water of West Germany is very low, with rare exceptions. Fluoride intake with food therefore is inadequate. Consequently, for maintenance of normal dental health, fluoride has to be supplemented by some way. A number of methods of fluoride supplementation are being discussed in this paper and compared to drinking waster fluoridation.

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

    PubMed Central

    Carey, Clifton M.

    2014-01-01

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

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

    PubMed

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

    2014-01-01

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

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

    PubMed

    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. PMID:24173035

  18. Critique of the review of 'Water fluoridation for the prevention of dental caries' published by the Cochrane Collaboration in 2015.

    PubMed

    Rugg-Gunn, A J; Spencer, A J; Whelton, H P; Jones, C; Beal, J F; Castle, P; Cooney, P V; Johnson, J; Kelly, M P; Lennon, M A; McGinley, J; O'Mullane, D; Sgan-Cohen, H D; Sharma, P P; Thomson, W M; Woodward, S M; Zusman, S P

    2016-04-01

    The Cochrane Review on water fluoridation for the prevention of dental caries was published in 2015 and attracted considerable interest and comment, especially in countries with extensive water fluoridation programmes. The Review had two objectives: (i) to evaluate the effects of water fluoridation (artificial or natural) on the prevention of dental caries, and (ii) to evaluate the effects of water fluoridation (artificial or natural) on dental fluorosis. The authors concluded, inter alia, that there was very little contemporary evidence, meeting the Review's inclusion criteria, that evaluated the effectiveness of water fluoridation for the prevention of dental caries. The purpose of this critique is to examine the conduct of the above Review, and to put it into context in the wider body of evidence regarding the effectiveness of water fluoridation. While the overall conclusion that water fluoridation is effective in caries prevention agrees with previous reviews, many important public health questions could not be answered by the Review because of the restrictive criteria used to judge adequacy of study design and risk of bias. The potential benefits of using wider criteria in order to achieve a fuller understanding of the effectiveness of water fluoridation are discussed. PMID:27056513

  19. Salivary fluoride levels after use of high-fluoride dentifrice.

    PubMed

    Vale, Glauber Campos; Cruz, Priscila Figueiredo; Bohn, Ana Clarissa Cavalcante Elvas; de Moura, Marcoeli Silva

    2015-01-01

    The aim of the study was to evaluate salivary fluoride (F) availability after toothbrushing with a high-F dentifrice. Twelve adult volunteers took part in this crossover and blind study. F concentration in saliva was determined after brushing with a high-F dentifrice (5000 µg F/g) or with a conventional F concentration dentifrice (1100 µg F/g) followed by a 15 mL distilled water rinse. Samples of nonstimulated saliva were collected on the following times: before (baseline), and immediately after spit (time = 0) and after 1, 2, 3, 4, 5, 10, 15, 20, 30, 45, 60, 90, and 120 min. F analysis was performed with a fluoride-sensitive electrode and the area under curve of F salivary concentration × time (µg F/mL × min(-1)) was calculated. At baseline, no significant difference was found among dentifrices (P > 0.05). After brushing, both dentifrices caused an elevated fluoride level in saliva; however salivary F concentration was significantly higher at all times, when high-F dentifrice was used (P < 0.01). Even after 120 min, salivary F concentration was still higher than the baseline values for both dentifrices (P < 0.001). High-F dentifrice enhanced the bioavailability of salivary F, being an option for caries management in patients with high caries risk.

  20. The Public Health Reach of High Fluoride Vehicles: Examples of Innovative Approaches.

    PubMed

    Tellez, Marisol; Wolff, Mark S

    2016-01-01

    Fluorides and sealants have been shown to reduce caries in populations, making fluoride interventions a large part of the dental public health effort. Although public health programs have traditionally focused on fluoride vehicles delivering less than 1,000 ppm of fluoride, more recent efforts have shifted toward the use of high fluoride vehicles such as varnishes and prescription toothpastes. In the USA, states are developing innovative strategies to increase access to dental services by using primary care medical providers to deliver early preventive services as part of well-child care visits. Currently, Medicaid programs in 43 states reimburse medical providers for preventive services including varnish application. Still, there is uncertainty about the cost-effectiveness of such interventions. In many resource-strained environments, with shortages of dental health care providers, lack of fluoridated water and lower dental awareness, it is necessary to develop sustainable programs utilizing already established programs, like primary school education, where caries prevention may be set as a priority. Dental caries among the elderly is an ongoing complex problem. The 5,000-ppm F toothpaste may be a reasonable approach for developing public health programs where root caries control is the main concern. Fluoride varnish and high concentration fluoride toothpaste are attractive because they can easily be incorporated into well-child visits and community-based geriatric programs. Additional research on the effectiveness and costs associated with population-based programs of this nature for high risk groups is needed, especially in areas where a community-based fluoride delivery program is not available.

  1. The Public Health Reach of High Fluoride Vehicles: Examples of Innovative Approaches.

    PubMed

    Tellez, Marisol; Wolff, Mark S

    2016-01-01

    Fluorides and sealants have been shown to reduce caries in populations, making fluoride interventions a large part of the dental public health effort. Although public health programs have traditionally focused on fluoride vehicles delivering less than 1,000 ppm of fluoride, more recent efforts have shifted toward the use of high fluoride vehicles such as varnishes and prescription toothpastes. In the USA, states are developing innovative strategies to increase access to dental services by using primary care medical providers to deliver early preventive services as part of well-child care visits. Currently, Medicaid programs in 43 states reimburse medical providers for preventive services including varnish application. Still, there is uncertainty about the cost-effectiveness of such interventions. In many resource-strained environments, with shortages of dental health care providers, lack of fluoridated water and lower dental awareness, it is necessary to develop sustainable programs utilizing already established programs, like primary school education, where caries prevention may be set as a priority. Dental caries among the elderly is an ongoing complex problem. The 5,000-ppm F toothpaste may be a reasonable approach for developing public health programs where root caries control is the main concern. Fluoride varnish and high concentration fluoride toothpaste are attractive because they can easily be incorporated into well-child visits and community-based geriatric programs. Additional research on the effectiveness and costs associated with population-based programs of this nature for high risk groups is needed, especially in areas where a community-based fluoride delivery program is not available. PMID:27099929

  2. Silicon oxidation in fluoride solutions

    NASA Technical Reports Server (NTRS)

    Sancier, K. M.; Kapur, V.

    1980-01-01

    Silicon is produced in a NaF, Na2SiF6, and Na matrix when SiF4 is reduced by metallic sodium. Hydrogen is evolved during acid leaching to separate the silicon from the accompanying reaction products, NaF and Na2SiF6. The hydrogen evolution reaction was studied under conditions simulating leaching conditions by making suspensions of the dry silicon powder in aqueous fluoride solutions. The mechanism for the hydrogen evolution is discussed in terms of spontaneous oxidation of silicon resulting from the cooperative effects of (1) elemental sodium in the silicon that reacts with water to remove a protective silica layer, leaving clean reactive silicon, and (2) fluoride in solution that complexes with the oxidized silicon in solution and retards formation of a protective hydrous oxide gel.

  3. DISSOLUTION OF LANTHANUM FLUORIDE PRECIPITATES

    DOEpatents

    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.

  4. Systematic review of water fluoridation

    PubMed Central

    McDonagh, Marian S; Whiting, Penny F; Wilson, Paul M; Sutton, Alex J; Chestnutt, Ivor; Cooper, Jan; Misso, Kate; Bradley, Matthew; Treasure, Elizabeth; Kleijnen, Jos

    2000-01-01

    Objective To review the safety and efficacy of fluoridation of drinking water. Design Search of 25 electronic databases and world wide web. Relevant journals hand searched; further information requested from authors. Inclusion criteria were a predefined hierarchy of evidence and objectives. Study validity was assessed with checklists. Two reviewers independently screened sources, extracted data, and assessed validity. Main outcome measures Decayed, missing, and filled primary/permanent teeth. Proportion of children without caries. Measure of effect was the difference in change in prevalence of caries from baseline to final examination in fluoridated compared with control areas. For potential adverse effects, all outcomes reported were used. Results 214 studies were included. The quality of studies was low to moderate. Water fluoridation was associated with an increased proportion of children without caries and a reduction in the number of teeth affected by caries. The range (median) of mean differences in the proportion of children without caries was −5.0% to 64% (14.6%). The range (median) of mean change in decayed, missing, and filled primary/permanent teeth was 0.5 to 4.4 (2.25) teeth. A dose-dependent increase in dental fluorosis was found. At a fluoride level of 1 ppm an estimated 12.5% (95% confidence interval 7.0% to 21.5%) of exposed people would have fluorosis that they would find aesthetically concerning. Conclusions The evidence of a beneficial reduction in caries should be considered together with the increased prevalence of dental fluorosis. There was no clear evidence of other potential adverse effects. PMID:11021861

  5. Is fluoride-induced hyperthyroidism a cause of psychosis among East African immigrants to Scandinavia?

    PubMed

    Zachariassen, Karl Erik; Flaten, Trond Peder

    2009-05-01

    East African immigrants to Scandinavia are admitted to mental hospitals far more frequently than native Scandinavians. Most of these patients are admitted for psychosis, commonly ascribed to problems adapting to the new culture. However, psychosis is also known to be associated with hyperthyroidism, and the high frequency of psychosis among East Africans in Scandinavia may at least in part be due to hyperthyroidism rather than cultural problems. Large areas in East Africa are notorious for high natural concentrations of fluoride in water and plants. Fluoride inhibits the production of thyroid hormones. To maintain normal thyroxin levels the body increases the capacity for thyroxin production. Goitre is caused by such a compensatory mechanism, and endemic goitre is widespread in many high-fluoride areas, even where dietary access to iodine is adequate. When people from such areas arrive in a low-fluoride area, their elevated capacity to produce thyroid hormones may lead to hyperthyroidism and subsequently to psychosis. PMID:19201548

  6. Contamination of fluoride in groundwater and its effect on human health: a case study in hard rock aquifers of Siddipet, Telangana State, India

    NASA Astrophysics Data System (ADS)

    Narsimha, A.; Sudarshan, V.

    2016-06-01

    Hydrogeochemical investigation has been carried out in the granitic terrain of Siddipet area, Medak district, Telangana State, India with an aim to understand the distribution of fluoride in the groundwater and to understand the relationship of fluoride with other major ions, and also to identify the high fluoride-bearing groundwater zones. 104 groundwater samples were analyzed in the study area for fluoride and other major ions like calcium, magnesium, chloride, carbonate, bicarbonate, sodium, potassium, sulfate, and nitrate in addition to pH and electrical conductivity. The studies revealed that the concentration of fluoride in groundwater is ranging from 0.2 to 2.2 mg L-1 with a mean of 1.1 mg L-1. Nearly 22 % of groundwater has more than the permissible limit of fluoride (1.5 mg L-1), which is responsible for the endemic dental fluorosis in the area concerned. Geochemical classification of groundwater shows that Na-HCO3, Ca-Cl, and Ca-HCO3-Na are the dominant hydrochemical facies. Gibbs diagram shows rock-water interaction dominance and evaporation dominance, which are responsible for the change in the quality of water in the hard rock aquifer of the study area. The groundwater in villages and its environs are affected by fluoride contamination, and consequently majority of the population living in these villages suffer from dental fluorosis. Hence, they are advised to consume drinking water which has less than 1.5 mg L-1 fluoride to avoid further fluorosis risks.

  7. Fluoride excretion of adults living in border regions with either water or salt fluoridation.

    PubMed

    Guindy, Joseph S; Gysin, Ralph; Kränzlin, Marius; Gasser, Thomas C; Hauck, Kirsten; Meyer, Jürg

    2006-01-01

    The canton of Basel-Stadt was the only canton in Switzerland which introduced drinking water fluoridation (DWF) at 1 ppm (mg/l). All other cantons have relied on fluoridated domestic salt at 250 ppm F as the main vehicle for basic fluoride exposure. It has been suggested that persons living and working in the DWF areas or persons commuting to the DWF areas may be exposed to higher than optimal doses of fluoride. The objective of this present study was to determine the urinary fluoride excretion of adults living and or working in neighboring areas of either salt or water fluoridation. In this study, 24-hour urine was collected from 69 healthy subjects and tested for fluoride concentration. The mean fluoride concentration for all participants was 0.55 +/- 0.25 ppm (mg/l) ranging from 1.14 to 0.09 ppm. The mean fluoride excretion was 0.95 +/- 0.47 mg F/d ranging from 0.18 to 2.12 mg F/d. The 33 subjects living in a DWF region showed a mean urine fluoride concentration of 0.64 +/- 0.24 ppm (mg/l) and a mean fluoride excretion of 1.14 +/- 0.48 mg F/d. Those 36 subjects living in a region without DWF showed a mean urine fluoride concentration of 0.47 +/- 0.24 ppm (mg/l) and a mean fluoride excretion of 0.78 +/- 0.40 mg F/d. A significant difference between the two means of the groups living in regions with or without DWF was detected when the Mann-Whitney statistical test was applied (p < 0.005). The combined intake of fluoridated drinking water and fluoridated table salt in the sub-group of 11 subjects who commuted showed an overall increase in fluoride urine concentration. The measured values, however, were not significantly different from the other sub-groups.

  8. Exposure to High Fluoride Drinking Water and Risk of Dental Fluorosis in Estonia

    PubMed Central

    Indermitte, Ene; Saava, Astrid; Karro, Enn

    2009-01-01

    The purpose of this study was to assess exposure to drinking water fluoride and evaluate the risk of dental fluorosis among the Estonian population. The study covered all 15 counties in Estonia and 93.7% of population that has access to public water supplies. In Estonia groundwater is the main source for public water supply systems in most towns and rural settlements. The content of natural fluoride in water ranges from 0.01 to 7.20 mg/L. The exposure to different fluoride levels was assessed by linking data from previous studies on drinking water quality with databases of the Health Protection Inspectorate on water suppliers and the number of water consumers in water supply systems. Exposure assessment showed that 4% of the study population had excessive exposure to fluoride, mainly in small public water supplies in western and central Estonia, where the Silurian-Ordovician aquifer system is the only source of drinking water. There is a strong correlation between natural fluoride levels and the prevalence of dental fluorosis. Risk of dental fluorosis was calculated to different fluoride exposure levels over 1.5 mg/L. PMID:19440411

  9. FLUORIDATION CHEMISTRY: EQUILIBRIA AND KINETICS OF FLUORIDE AND FLUORO-COMPLEXES

    EPA Science Inventory

    The most common fluoridating agents used by major American waterworks are hexafluorosilicic acid (H2SiF6) and sodium hexxafluorosilicate (Na2SiF6). According to the 1992 Water Fluoridation Census where 10,002 utilities responded affirmatively to fluoridating their water, 59
    % ...

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

    DOEpatents

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

    1958-08-12

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

  11. Spinning up the polymorphs of calcium carbonate

    PubMed Central

    Boulos, Ramiz A.; Zhang, Fei; Tjandra, Edwin S.; Martin, Adam D.; Spagnoli, Dino; Raston, Colin L.

    2014-01-01

    Controlling the growth of the polymorphs of calcium carbonate is important in understanding the changing environmental conditions in the oceans. Aragonite is the main polymorph in the inner shells of marine organisms, and can be readily converted to calcite, which is the most stable polymorph of calcium carbonate. Both of these polymorphs are significantly more stable than vaterite, which is the other naturally occurring polymorph of calcium carbonate, and this is reflected in its limited distribution in nature. We have investigated the effect of high shear forces on the phase behaviour of calcium carbonate using a vortex fluidic device (VFD), with experimental parameters varied to explore calcium carbonate mineralisation. Variation of tilt angle, rotation speed and temperature allow for control over the size, shape and phase of the resulting calcium carbonate. PMID:24448077

  12. Occurrence and problems of high fluoride waters in Turkey: an overview.

    PubMed

    Oruc, Nazmi

    2008-08-01

    Endemic dental fluorosis was first observed in Turkey in Isparta Province, located in the SW of Anatolia, with mottled enamel related to the high levels of fluoride (1.5-4.0 ppm) in drinking waters, about 55 years ago. The origin of fluoride was attributed to the contents of minerals in volcanic rocks, consisting of pyroxene, hornblende, biotite, fluorapatite and glassy groundmass minerals. It was also reported about 35 years ago that severe dental and skeletal fluorosis has been observed in human beings and livestock in Dogubeyazit and Caldiran areas, located around Tendurek Volcano in eastern Turkey, where natural waters contained fluoride levels between 2.5 and 12.5 ppm. It was hypothesised that fluoride, which might be transported by fumaroles or escaped from devitrified lavas, could be held on the surface of some minerals and then exchanged with OH(-) in ground waters with high pH at the foothills of the young Tendurek Volcano. Endemic dental and skeletal fluorosis was also observed in the inhabitants in Kizilcaoren Village of Beylikova Town in Eskişehir Province situated in the midwest of Turkey, where the fluoride content of the drinking waters ranged from 3.9 to 4.8 ppm. The origin of high fluoride in the natural waters was related to the fluorspar deposits, occurring in the catchment area near the village. During the survey in the Güllü Village of Esme-Usak, located in south-midwest of Turkey, it was observed that most of the inhabitants born and raised in the village and aged between 10 and 30 years, showed mild to moderate levels of mottled enamel. The fluoride contents of the deep well waters used for drinking in the village, varied from 0.7 to 2.0 ppm. Amorphous microscopic fluorite existing in the Pliocene lake limestones was considered as a possible origin of fluoride in the waters.

  13. Occurrence and problems of high fluoride waters in Turkey: an overview.

    PubMed

    Oruc, Nazmi

    2008-08-01

    Endemic dental fluorosis was first observed in Turkey in Isparta Province, located in the SW of Anatolia, with mottled enamel related to the high levels of fluoride (1.5-4.0 ppm) in drinking waters, about 55 years ago. The origin of fluoride was attributed to the contents of minerals in volcanic rocks, consisting of pyroxene, hornblende, biotite, fluorapatite and glassy groundmass minerals. It was also reported about 35 years ago that severe dental and skeletal fluorosis has been observed in human beings and livestock in Dogubeyazit and Caldiran areas, located around Tendurek Volcano in eastern Turkey, where natural waters contained fluoride levels between 2.5 and 12.5 ppm. It was hypothesised that fluoride, which might be transported by fumaroles or escaped from devitrified lavas, could be held on the surface of some minerals and then exchanged with OH(-) in ground waters with high pH at the foothills of the young Tendurek Volcano. Endemic dental and skeletal fluorosis was also observed in the inhabitants in Kizilcaoren Village of Beylikova Town in Eskişehir Province situated in the midwest of Turkey, where the fluoride content of the drinking waters ranged from 3.9 to 4.8 ppm. The origin of high fluoride in the natural waters was related to the fluorspar deposits, occurring in the catchment area near the village. During the survey in the Güllü Village of Esme-Usak, located in south-midwest of Turkey, it was observed that most of the inhabitants born and raised in the village and aged between 10 and 30 years, showed mild to moderate levels of mottled enamel. The fluoride contents of the deep well waters used for drinking in the village, varied from 0.7 to 2.0 ppm. Amorphous microscopic fluorite existing in the Pliocene lake limestones was considered as a possible origin of fluoride in the waters. PMID:18335173

  14. Lithological Influences on Occurrence of High-Fluoride Waters in The Central Kenya Rift

    NASA Astrophysics Data System (ADS)

    Olaka, L. A.; Musolff, A.; Mulch, A.; Olago, D.; Odada, E. O.

    2013-12-01

    Within the East African rift, groundwater recharge results from the complex interplay of geology, land cover, geomorphology, climate and on going volcano-tectonic processes across a broad range of spatial and temporal scales. The interrelationships between these factors create complex patterns of water availability, reliability and quality. The hydrochemical evolution of the waters is further complex due to the different climatic regimes and geothermal processes going on in this area. High fluoridic waters within the rift have been reported by few studies, while dental fluorosis is high among the inhabitants of the rift. The natural sources of fluoride in waters can be from weathering of fluorine bearing minerals in rocks, volcanic or fumarolic activities. Fluoride concentration in water depends on a number of factors including pH, temperature, time of water-rock formation contact and geochemical processes. Knowledge of the sources and dispersion of fluoride in both surface and groundwaters within the central Kenya rift and seasonal variations between wet and dry seasons is still poor. The Central Kenya rift is marked by active tectonics, volcanic activity and fumarolic activity, the rocks are majorly volcanics: rhyolites, tuffs, basalts, phonolites, ashes and agglomerates some are highly fractured. Major NW-SE faults bound the rift escarpment while the rift floor is marked by N-S striking faults We combine petrographic, hydrochemistry and structural information to determine the sources and enrichment pathways of high fluoridic waters within the Naivasha catchment. A total of 120 water samples for both the dry season (January-February2012) and after wet season (June-July 2013) from springs, rivers, lakes, hand dug wells, fumaroles and boreholes within the Naivasha catchment are collected and analysed for fluoride, physicochemical parameters and stable isotopes (δ2 H, δ18 O) in order to determine the origin and evolution of the waters. Additionally, 30 soil and

  15. Calcium and Vitamin D

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calcium is required for the bone formation phase of bone remodeling. Typically about 5 nmol (200 mg) of calcium is removed from the adult skeleton and replaced each day. To supply this amount, one would need to consume about 600 mg of calcium, since calcium is not very efficiently absorbed. Calcium ...

  16. Fluoride blocks an inactivation step of transduction in a locust photoreceptor

    PubMed Central

    Payne, Richard

    1982-01-01

    1. Photoreceptors in a superfused retina of a locust compound eye are treated with saline containing 10 mM-NaF, while their intracellular resting potential and responses are recorded using glass micropipettes. 2. Treatment for two minutes with 10 mM-NaF, followed by a series of brief, bright flashes of light, results in an irreversible, noisy depolarization of approximately 10 mV. The final, stable level of depolarization is reached through the summed effect of each of the noisy, depolarizing afterpotentials that follow every response of the cell to a light flash. If kept in darkness after treatment with NaF, the noisy depolarization still develops, but more gradually, over a period of 5 min. 3. The voltage noise induced by NaF mimics light-induced voltage noise when the two are compared at mean depolarizations of more than 15 mV. At very small depolarizations, however, fluoride-induced noise cannot be resolved into the large discrete events (bumps) that are typical of the response of a dark-adapted photoreceptor to a single photon. 4. The complete replacement of the superfusate sodium by choline reversibly reduces the fluoride-induced noise and depolarization to the same extent as it does the light-induced noise and depolarization of an illuminated cell. 5. Increasing the superfusate calcium concentration from 0·5 to 10 mM also reversibly reduces fluoride-induced noise and depolarization to the same extent as it does light-induced noise and depolarization. This action of calcium is accompanied by an increase in a cell's input resistance which opposes the reduction caused by light or fluoride treatment. 6. The results confirm the proposal (Payne, 1981) that anionic metabolic inhibitors cause spontaneous activity in sodium channels that are normally opened by light. A model is proposed in which fluoride acts by blocking the inactivation of a late stage in the transduction mechanism. PMID:6286940

  17. Fluorescent Sensing of Fluoride in Cellular System

    PubMed Central

    Jiao, Yang; Zhu, Baocun; Chen, Jihua; Duan, Xiaohong

    2015-01-01

    Fluoride ions have the important roles in a lot of physiological activities related with biological and medical system, such as water fluoridation, caries treatment, and bone disease treatment. Great efforts have been made to develop new methods and strategies for F- detection in the past decades. Traditional methods for the detection of F- including ion chromatography, ion-selective electrodes, and spectroscopic techniques have the limitations in the biomedicine research. The fluorescent probes for F- are very promising that overcome some drawbacks of traditional fluoride detection methods. These probes exhibit high selectivity, high sensitivity as well as quick response to the detection of fluoride anions. The review commences with a brief description of photophysical mechanisms for fluorescent probes for fluoride, including photo induced electron transfer (PET), intramolecular charge transfer (ICT), fluorescence resonance energy transfer (FRET), and excited-state intramolecular proton transfer (ESIPT). Followed by a discussion about common dyes for fluorescent fluoride probes, such as anthracene, naphalimide, pyrene, BODIPY, fluorescein, rhodamine, resorufin, coumarin, cyanine, and near-infrared (NIR) dyes. We divide the fluorescent probes for fluoride in cellular application systems into nine groups, for example, type of hydrogen bonds, type of cleavage of Si-O bonds, type of Si-O bond cleavage and cylization reactions, etc. We also review the recent reported carriers in the delivery of fluorescent fluoride probes. Seventy-four typical fluorescent fluoride probes are listed and compared in detail, including quantum yield, reaction medium, excitation and emission wavelengths, linear detection range, selectivity for F-, mechanism, and analytical applications. Finally, we discuss the future challenges of the application of fluorescent fluoride probes in cellular system and in vivo. We wish that more and more excellent fluorescent fluoride probes will be developed

  18. Fluoride in drinking water and dental fluorosis.

    PubMed

    Mandinic, Zoran; Curcic, Marijana; Antonijevic, Biljana; Carevic, Momir; Mandic, Jelena; Djukic-Cosic, Danijela; Lekic, Charles P

    2010-08-01

    In this study we determined the fluoride content in drinking water and hair of 12-year-old schoolchildren from different Serbian municipalities, i.e. Valjevo, Veliko Gradiste, Kacarevo and Vranjska Banja. The analyses were performed using composite fluoride ion-selective electrode. Average fluoride levels were 0.10, 0.15, 0.79 and 11 ppm in well water, 0.07, 0.10, 0.17 and 0.15 ppm in tap water, 19.3, 21.5, 25.4, and 32.5 ppm in hair samples, in Valjevo, Veliko Gradiste, Kacarevo and Vranjska Banja, respectively. Correlation analysis indicated statistically significant positive relationship between fluoride in wells water and fluoride in hair, for all municipalities: correlation coefficients were 0.54 (p < 0.05), 0.89, 0.97 and 0.99 (p < 0.001), in Vranjska Banja, Valjevo, Veliko Gradiste, and Kacarevo, respectively. Positive correlation was obtained also between fluoride in tap water and hair samples in all regions under the study, with statistical significance only in Valjevo municipality, p < 0.05. Dental examination of schoolchildren confirmed dental fluorosis only in the region of Vranjska Banja. Moreover, in endemic fluorotic region of Vranjska Banja, positive and statistically significant correlations were confirmed between fluoride in well water and dental fluorosis level (r = 0.61; p < 0.01) and additionally between fluoride in hair and dental fluorosis level (0.62; p < 0.01). The primary findings from this study have shown that fluoride content in hair is highly correlated with fluoride content in drinking water and dental fluorosis level, indicating that hair may be regarded as biomaterial of high informative potential in evaluating prolonged exposure to fluorides and to individuate children at risk of fluorosis regardless of the phase of teeth eruption. PMID:20580811

  19. Comparative Evaluation of Longevity of Fluoride Release From three Different Fluoride Varnishes – An Invitro Study

    PubMed Central

    Roshan, NM; Poornima, P; Nagaveni, NB; Neena, IE; Bharath, KP

    2016-01-01

    Introduction Fluoride varnishes play a pivotal role in inhibition of dental caries by increasing remineralization. Aim To determine the longevity of fluoride release from 3 different fluoride varnishes over a period of time through salivary fluoride estimation. Materials and Methods Twenty four extracted human deciduous anterior teeth were divided into four groups, i.e., ClinproTM XT, Flouritop SR, Flourprotector and Control group. Fluoride varnishes were applied on 3mm x 3mm window on labial surface of the teeth and then the teeth were immersed and stored in artificial saliva. The concentration of fluoride in ppm was measured after 1 week, 1 month, 3 months and 6 months. Fluoride release at each time interval for different groups was statistically analyzed using ANOVA and Post Hoc Tukey’s test. Results Although all the fluoride varnishes released fluoride, with greatest release observed during 1st week by Fluoritop SR (66.92±16.30ppm), ClinproTM XT Varnish released consistently and substantially more fluoride than Fluoritop SR and Fluorprotector during 6 months analysis (p<0.05). Fluorprotector showed the lowest rate of F release among all the groups compared. Conclusion Over a period of 6 months ClinproTM XT Varnish released consistently and substantially more fluoride than other tested products. PMID:27656559

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

    PubMed Central

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

    2008-01-01

    A biomarker for lifetime fluoride exposure would facilitate population-based research and policy making but currently does not exist. This study examined the suitability of primary tooth dentin as a biomarker by comparing dentin fluoride concentration and fluoride exposures. Ninety-nine children's exfoliated primary teeth were collected from 2 fluoridated and 2 fluoride-deficient communities in North Carolina. Coronal dentin was isolated by microdissection and fluoride concentration assayed using the microdiffusion, ion-specific electrode technique. Information on children's fluoride exposures since birth from drinking water, toothpaste, supplements, rinses, food and beverages was collected by a self-reported questionnaire administered to caregivers. Only a small portion of the variance (10%) in incisor dentin fluoride (mean 792, SD 402 mg/kg) was accounted for by the best linear regression model as evaluated by the adjusted R2. A moderate portion of the variance (60%) of molar dentin fluoride (mean 768, SD 489 mg/kg) was predicted by dietary fluoride supplement exposures, community of residence, and frequent tea consumption. Results for molars suggest that primary tooth dentin concentration may prove to be a satisfactory biomarker for fluoride exposure. PMID:18832828

  1. Fluoride concentration in dentin of exfoliated primary teeth as a biomarker for cumulative fluoride exposure.

    PubMed

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

    2008-01-01

    A biomarker for lifetime fluoride exposure would facilitate population-based research and policy making but currently does not exist. This study examined the suitability of primary tooth dentin as a biomarker by comparing dentin fluoride concentration and fluoride exposures. Ninety-nine children's exfoliated primary teeth were collected from 2 fluoridated and 2 fluoride-deficient communities in North Carolina. Coronal dentin was isolated by microdissection and fluoride concentration assayed using the microdiffusion, ion-specific electrode technique. Information on children's fluoride exposures since birth from drinking water, toothpaste, supplements, rinses, food and beverages was collected by a self-reported questionnaire administered to caregivers. Only a small portion of the variance (10%) in incisor dentin fluoride (mean 792, SD 402 mg/kg) was accounted for by the best linear regression model as evaluated by the adjusted R(2). A moderate portion of the variance (60%) of molar dentin fluoride (mean 768, SD 489 mg/kg) was predicted by dietary fluoride supplement exposures, community of residence, and frequent tea consumption. Results for molars suggest that primary tooth dentin concentration may prove to be a satisfactory biomarker for fluoride exposure.

  2. The effect of fluoride contents in fluoridated hydroxyapatite on osteoblast behavior.

    PubMed

    Qu, Haibo; Wei, Mei

    2006-01-01

    Fluoridated hydroxyapatite (FHA) discs with various fluoride contents (0-0.567 mol F(-)/mol) [corrected] have been used to investigate the effect of fluoride content on osteoblastic cell behavior. SAOS-3 rat osteosarcoma cells were cultured on FHA discs for different time periods. The cell behavior was examined in terms of cell attachment, proliferation, morphology and differentiation. The fluoride content in FHA discs strongly affected the cell activities. More cell attachment and proliferation were observed on the fluoride-containing FHA discs than on pure hydroxyapatite (HA). The fluoride content also affected the differentiation behavior of osteoblastic cells. Cells on FHA discs demonstrated a higher alkaline phosphatase (ALP) activity than those on pure HA after 2 [corrected] weeks of culturing. These results suggested that fluoride ions have a significant impact on different osteoblastic cell activities.

  3. Arsenic and fluoride in the groundwater of Mexico.

    PubMed

    Armienta, M A; Segovia, N

    2008-08-01

    Concentrations of arsenic and fluoride above Mexican drinking water standards have been detected in aquifers of various areas of Mexico. This contamination has been found to be mainly caused by natural sources. However, the specific processes releasing these toxic elements into groundwater have been determined in a few zones only. Many studies, focused on arsenic-related health effects, have been performed at Comarca Lagunera in northern México. High concentrations of fluoride in water were also found in this area. The origin of the arsenic there is still controversial. Groundwater in active mining areas has been polluted by both natural and anthropogenic sources. Arsenic-rich minerals contaminate the fractured limestone aquifer at Zimapán, Central México. Tailings and deposits smelter-rich fumes polluted the shallow granular aquifer. Arsenic contamination has also been reported in the San Antonio-El Triunfo mining zone, southern Baja California, and Santa María de la Paz, in San Luis Potosí state. Even in the absence of mining activities, hydrogeochemistry and statistical techniques showed that arsenopyrite oxidation may also contaminate water, as in the case of the Independencia aquifer in the Mexican Altiplano. High concentrations of arsenic have also been detected in geothermal areas like Los Azufres, Los Humeros, and Acoculco. Prevalence of dental fluorosis was revealed by epidemiological studies in Aguascalientes and San Luis Potosí states. Presence of fluoride in water results from dissolution of acid-volcanic rocks. In Mexico, groundwater supplies most drinking water. Current knowledge and the geology of Mexico indicate the need to include arsenic and fluoride determinations in groundwater on a routine basis, and to develop interdisciplinary studies to assess the contaminant's sources in all enriched areas.

  4. Gain-of-function nature of Cav1.4 L-type calcium channels alters firing properties of mouse retinal ganglion cells

    PubMed Central

    Knoflach, Dagmar; Schicker, Klaus; Glösmann, Martin; Koschak, Alexandra

    2015-01-01

    Proper function of Cav1.4 L-type calcium channels is crucial for neurotransmitter release in the retina. Our understanding about how different levels of Cav1.4 channel activity affect retinal function is still limited. In the gain-of-function mouse model Cav1.4-IT we expected a reduction in the photoreceptor dynamic range but still transmission toward retinal ganglion cells. A fraction of Cav1.4-IT ganglion cells responded to light stimulation in multielectrode array recordings from whole-mounted retinas, but showed a significantly delayed response onset. Another significant number of cells showed higher activity in darkness. In addition to structural remodeling observed at the first retinal synapse of Cav1.4-IT mice the functional data suggested a loss of contrast enhancement, a fundamental feature of our visual system. In fact, Cav1.4-IT mouse retinas showed a decline in spatial response and changes in their contrast sensitivity profile. Photoreceptor degeneration was obvious from the nodular structure of cone axons and enlarged pedicles which partly moved toward the outer nuclear layer. Loss of photoreceptors was also expressed as reduced expression of proteins involved in chemical and electrical transmission, as such metabotropic glutamate receptor mGluR6 and the gap junction protein Connexin 36. Such gross changes in retinal structure and function could also explain the diminished visual performance of CSNB2 patients. The expression pattern of the plasma-membrane calcium ATPase 1 which participates in the maintenance of the intracellular calcium homeostasis in photoreceptors was changed in Cav1.4-IT mice. This might be part of a protection mechanism against increased calcium influx, as this is suggested for Cav1.4-IT channels. PMID:26274509

  5. Coronary Calcium Scan

    MedlinePlus

    ... the NHLBI on Twitter. What Is a Coronary Calcium Scan? A coronary calcium scan is a test ... you have calcifications in your coronary arteries. Coronary Calcium Scan Figure A shows the position of the ...

  6. Calcium and bones (image)

    MedlinePlus

    Calcium is one of the most important minerals for the growth, maintenance, and reproduction of the human ... body, are continually being re-formed and incorporate calcium into their structure. Calcium is essential for the ...

  7. Calcium hydroxide poisoning

    MedlinePlus

    Hydrate - calcium; Lime milk; Slaked lime ... Calcium hydroxide ... These products contain calcium hydroxide: Cement Limewater Many industrial solvents and cleaners (hundreds to thousands of construction products, flooring strippers, brick cleaners, cement ...

  8. Calcium source (image)

    MedlinePlus

    Getting enough calcium to keep bones from thinning throughout a person's life may be made more difficult if that person has ... as a tendency toward kidney stones, for avoiding calcium-rich food sources. Calcium deficiency also effects the ...

  9. Geochemistry of fluoride in the Black Creek aquifer system of Horry and Georgetown Counties, South Carolina--and its physiological implications

    USGS Publications Warehouse

    Zack, Allen L.

    1980-01-01

    High concentrations of fluoride in ground-water supplies in certain areas of Horry and Georgetown Counties, S.C., have been the cause of dental fluorosis (tooth mottling) among persons who have lived in these areas and have ingested the water as children. Geochemical evidence and laboratory experiments demonstrate that fluorapatite in the form of fossil shark teeth is the source of fluoride, and that the fluoride ions are liberated to the ground-water system through anion exchange, rather than by dissolution. Calcite-cemented quartz sand in the upper third of the Black Creek Formation of Late Cretaceous age contains the fossil shark teeth. As ground water progresses downdip, the calcite matrix dissolves and hydrolyzes, releasing bicarbonate, hydroxyl, and calcium ions. The calcium ions are immediately exchanged for sodium ions adsorbed on sodium-rich clays, and the bicarbonate ions accumulate. As the shark teeth are exposed, the hydroxyl ions in solution exchange with fluoride ions on fluorapatite surfaces. Experiments using fossil shark teeth show that sodium chloride in solution inhibits the rate of exchange of fluoride ions from tooth surfaces for hydroxyl ions in solution. The amount of fluoride removed from water and exchanged for hydroxyl ions in the presence of pure hydroxylapatite (hog teeth) was greater in saline water than in freshwater.

  10. Crystallinity and solubility behavior of iron-containing fluoridated hydroxyapatites.

    PubMed

    Okazaki, M; Takahashi, J; Kimura, H

    1986-09-01

    Iron-containing fluoridated hydroxyapatites with various fluoride contents were synthesized at 80 degrees C and pH 7.4 using FeCl2 X nH2O as a source of iron. The Fe2+ uptake of fluoridated apatites was independent of fluoride concentration in the solution. a-Axis dimensions of Fe-containing apatites decreased with the degree of fluoridation in addition to the decrease related to the substitution of Fe2+ ions. All Fe-containing fluoridated apatites were less well crystallized than Fe-free fluoridated apatites previously reported, although with increasing degree of fluoridation, the crystallinity behavior of the former apatites appeared analogous to that of the latter apatites. In contrast to this inhibited crystallinity behavior, the apparent solubility of Fe-containing fluoridated apatites decreased more than that of Fe-free fluoridated apatites at low fluoride content.

  11. Fluoride dentifrices: current status and prospects.

    PubMed

    Mellberg, J R

    1991-02-01

    Toothpastes have developed from the poorly effective formulations using incompatible abrasive systems to the highly effective products now being given credit for the decline in dental caries in most developed countries. The earliest toothpastes used sodium fluoride but this was soon replaced by stannous fluoride, sodium monofluorophosphate and amine fluoride. Monofluorophosphate has the advantage that it is compatible with a wide variety of abrasive systems. Although most toothpastes world-wide currently contain monofluorophosphate, sodium fluoride formulations are growing in availability because of the development of compatible abrasives. Clinical caries trials have indicated that, with proper formulation, there is little or no difference in effectiveness among toothpastes prepared with different fluoride agents, but that increasing the fluoride concentration will enhance the anti-caries effect. The addition of other active agents to fluoride toothpaste has been a relatively recent occurrence, and it is important to be assured that they do not interfere with the anti-caries activity of fluoride. Pyrophosphate, a calculus control agent, is one additive that was considered to be a potential problem; however, human and animal tests have shown that both caries and calculus inhibiting effects can be obtained from a single formulation. With the use of modern methodology to evaluate toothpaste formulations before clinical trials, many new products containing anti-calculus and other agents will probably become available in the coming years.

  12. Method of making porous ceramic fluoride

    DOEpatents

    Reiner, Robert H.; Holcombe, Cressie E.

    1990-01-01

    A process for making a porous ceramic composite where fumed silica particles are coated with a nitrate, preferably aluminum nitrate. Next the nitrate is converted to an oxide and formed into a desired configuration. This configuration is heated to convert the oxide to an oxide silicate which is then react with HF, resulting in the fluoride ceramic, preferably aluminum fluoride.

  13. Growth of hollow nickel fluoride whiskers

    SciTech Connect

    Petrov, S. V.; Orekhov, Yu. F.; Fedorov, P. P.

    2009-07-15

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

  14. Xenon fluoride solutions effective as fluorinating agents

    NASA Technical Reports Server (NTRS)

    Hyman, H. H.; Quarterman, L. A.; Sheft, I.

    1967-01-01

    Solutions of xenon fluorides in anhydrous hydrogen fluoride have few disruptive effects and leave a residue consisting of gaseous xenon, which can be recovered and refluorinated. This mild agent can be used with materials which normally must be fluorinated with fluorine alone at high temperatures.

  15. Welsh water should reinstate fluoridation on Anglesey.

    PubMed

    Hulse, G; Kenrick, A; Thomas, C H; Thomas, A; Davies, D J; Lennon, M A

    1995-01-21

    In 1992, Welsh Water withdrew the successful water fluoridation scheme on Anglesey. Despite evidence of the benefits of water fluoridation and the rise in number of children with tooth decay since the scheme's withdrawal, Welsh Water is still not prepared to re-establish the scheme.

  16. Detection of free radicals formed by in vitro metabolism of fluoride using EPR spectroscopy.

    PubMed

    Pawłowska-Góral, Katarzyna; Pilawa, Barbara

    2011-10-01

    In many parts of the globe, where water contains large amount of fluoride, fluorosis is a serious public health problem. It is accompanied by many changes, not only in the bones, but practically in all organs of the body. Since it was discovered that oxidation stress, together with the peroxidation of lipids which accompanies it, results in many diseases, research has been carried out on this aspect of fluorosis. The findings, however, are incomplete and divergent. The aim of our study was to determine the presence of free radicals in hepatocytes exposed to fluoride in concentrations which do not lead to changes in the concentrations of calcium and magnesium ions. Free radical properties of hepatocytes incubated with fluoride were studied by an X-band electron paramagnetic resonance (EPR) spectroscopy. Hepatocytes are paramagnetic and broad unsymmetrical EPR spectra were obtained for them. Oxygen free radicals with g-factor of 2.0032 exist in hepatocytes. The effect of fluoride concentration and the time of incubation on free radicals amount in cells were examined. The amount of free radicals in hepatocytes increases with the increase of fluoride concentration for all the incubation times (10, 30, and 60 min). The amount of free radicals in hepatocytes decreases with the increase of time of incubation for all the used fluoride concentrations (0.002, 0.082, and 0.164 mmol/l). EPR spectra of the studied cells are homogeneously broadened. Continuous microwave saturation of EPR lines indicates that slow spin-lattice relaxation processes exist in the studied cells. Strong dipolar interactions responsible for the broadening (ΔB(pp): 1.45-1.87 mT) of the EPR spectra exist in the hepatocytes.

  17. Discovery of Interstellar Hydrogen Fluoride

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    We report the first detection of interstellar hydrogen fluoride. Using the Long Wavelength Spectrometer of the Infrared Space Observatory (ISO), we have detected the 121.6973 micron J = 2-1 line of HF in absorption toward the far-infrared continuum source Sagittarius B2. The detection is statistically significant at the 13 sigma level. On the basis of our model for the excitation of HF in Sgr B2, the observed line equivalent width of 1.0 nm implies a hydrogen fluoride abundance of approximately 3 x 10(exp -10) relative to H2. If the elemental abundance of fluorine in Sgr B2 is the same as that in the solar system, then HF accounts for approximately 2% of the total number of fluorine nuclei. We expect hydrogen fluoride to be the dominant reservoir of gas-phase fluorine in Sgr B2, because it is formed rapidly in exothermic reactions of atomic fluorine with either water or molecular hydrogen; thus, the measured HF abundance suggests a substantial depletion of fluorine onto dust grains. Similar conclusions regarding depletion have previously been reached for the case of chlorine in dense interstellar clouds. We also find evidence at a lower level of statistical significance (approximately 5 sigma) for an emission feature at the expected position of the 4(sub 32)-4(sub 23) 121.7219 micron line of water. The emission-line equivalent width of 0.5 nm for the water feature is consistent with the water abundance of 5 x 10(exp -6) relative to H2 that has been inferred previously from observations of the hot core of Sgr B2.

  18. Discovery of Interstellar Hydrogen Fluoride

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    We report the first detection of interstellar hydrogen fluoride. Using the Long Wavelength Spectrometer of the Infrared Space Observatory (ISO), we have detected the 121.6973 micron J = 2-1 line of HF in absorption toward the far-infrared continuum source Sagittarius B2. The detection is statistically significant at the 13 sigma level. On the basis of our model for the excitation of HF in Sgr B2, the observed line equivalent width of 1.0 nm implies a hydrogen fluoride abundance of about 3 x 10 (exp -10) relative to H, If the elemental abundance of fluorine in Sgr B2 is the same as that in the solar system, then HF accounts for about 2% of the total number of fluorine nuclei. We expect hydrogen fluoride to be the dominant reservoir of gas-phase fluorine in Sgr B2, because it is formed rapidly in exothermic reactions of atomic fluorine with either water or molecular hydrogen; thus, the measured HF abundance suggests a substantial depletion of fluorine onto dust grains. Similar conclusions regarding depletion have previously been reached for the case of chlorine in dense interstellar clouds. We also find evidence at a lower level of statistical significance (about 5 sigma) for an emission feature at the expected position of the 4(sub 32)-4(sub 23) 121.7219 micron line of water. The emission-line equivalent width of 0.5 mm for the water feature is consistent with the water abundance of 5 x 10(exp -6) relative to H, that has been inferred previously from observations of the hot core of Sgr B2.

  19. Fluoride removal by calcite: evidence for fluorite precipitation and surface adsorption.

    PubMed

    Turner, Brett D; Binning, Philip; Stipp, S L S

    2005-12-15

    Fluoride contamination of groundwater, both anthropogenic and natural, is a major problem worldwide. In this study, fluoride removal by crushed limestone (99% pure calcite) was investigated by batch studies and surface-sensitive techniques from solutions with fluoride concentrations from 150 micromol/L (3 mg/L) to 110 mM (approximately 2100 mg/L). Surface-sensitive techniques, including atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) as well as zeta potential measurements, confirm that, in addition to precipitation reactions, adsorption of fluoride also occurs. Results indicate that fluoride adsorption occurs immediately over the entire calcite surface with fluorite precipitating at step edges and kinks, where dissolved Ca2+ concentration is highest. The PHREEQ geochemical model was applied to the observed data and indicates that existing models, especially at low fluoride concentrations and high pH (>7.5) are not equipped to describe this complex system, largely because the PHREEQ model includes only precipitation reactions, whereas a combination of adsorption and precipitation parameters are required.

  20. Enduring Fluoride Health Hazard for the Vesuvius Area Population: The Case of AD 79 Herculaneum

    PubMed Central

    Petrone, Pierpaolo; Giordano, Michele; Giustino, Stefano; Guarino, Fabio M.

    2011-01-01

    Background The study of ancient skeletal pathologies can be adopted as a key tool in assessing and tracing several diseases from past to present times. Skeletal fluorosis, a chronic metabolic bone and joint disease causing excessive ossification and joint ankylosis, has been only rarely considered in differential diagnoses of palaeopathological lesions. Even today its early stages are misdiagnosed in endemic areas. Methodology/Principal Findings Endemic fluorosis induced by high concentrations of fluoride in water and soils is a major health problem in several countries, particularly in volcanic areas. Here we describe for the first time the features of endemic fluorosis in the Herculaneum victims of the 79 AD eruption, resulting from long-term exposure to high levels of environmental fluoride which still occur today. Conclusions/Significance Our observations on morphological, radiological, histological and chemical skeletal and dental features of this ancient population now suggest that in this area fluorosis was already endemic in Roman times. This evidence merged with currently available epidemiologic data reveal for the Vesuvius area population a permanent fluoride health hazard, whose public health and socio-economic impact is currently underestimated. The present guidelines for fluoridated tap water might be reconsidered accordingly, particularly around Mt Vesuvius and in other fluoride hazard areas with high natural fluoride levels. PMID:21698155

  1. The investigation of kinetic and isotherm of fluoride adsorption onto functionalize pumice stone.

    PubMed

    Asgari, Ghorban; Roshani, Babak; Ghanizadeh, Ghader

    2012-05-30

    In this research work, pumice that is functionalized by the cationic surfactant, hexadecyltrimethyl ammonium (HDTMA), is used as an adsorbent for the removal of fluoride from drinking water. This work was carried out in two parts. The effects of HDTMA loading, pH (3-10), reaction time (5-60 min) and the adsorbent dosage (0.15-2.5 g L(-1)) were investigated on the removal of fluoride as a target contaminate from water through the design of different experimental sets in the first part. The results from this first part revealed that surfactant-modified pumice (SMP) exhibited the best performance at dose 0.5 g L(-1), pH 6, and it adsorbs over 96% of fluoride from a solution containing 10 mg L(-1) fluoride after 30 min of mixing time. The four linear forms of the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms model were applied to determine the best fit of equilibrium expressions. Apart from the regression coefficient (R(2)), four error functions were used to validate the isotherm and kinetics data. The experimental adsorption isotherm complies with Langmuir equation model type 1. The maximum amount of adsorption (Q(max)) was 41 mg g(-1). The kinetic studies indicated that the adsorption of fluoride best fitted with the pseudo-second-order kinetic type 1. Thermodynamic parameters evaluation of fluoride adsorption on SMP showed that the adsorption process under the selected conditions was spontaneous and endothermic. The suitability of SMP in defluoridation at field condition was investigated with natural groundwater samples collected from a nearby fluoride endemic area in the second part of this study. Based on this study's results, SMP was shown to be an affordable and a promising option for the removal of fluoride in drinking water.

  2. Recent advancements in fluoride: A systematic review.

    PubMed

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

    2015-01-01

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

  3. Recent advancements in fluoride: A systematic review

    PubMed Central

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

    2015-01-01

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

  4. Method of treating fluoride contaminated wastes

    SciTech Connect

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

    1988-04-05

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

  5. The kinetics of fluoride sorption by zeolite: Effects of cadmium, barium and manganese.

    PubMed

    Cai, Qianqian; Turner, Brett D; Sheng, Daichao; Sloan, Scott

    2015-01-01

    Industrial wastewaters often consist of a complex chemical cocktail with treatment of target contaminants complicated by adverse chemical reactions. The impact of metal ions (Cd(2+), Ba(2+) and Mn(2+)) on the kinetics of fluoride removal from solution by natural zeolite was investigated. In order to better understand the kinetics, the pseudo-second order (PSO), Hill (Hill 4 and Hill 5) and intra-particle diffusion (IPD) models were applied. Model fitting was compared using the Akaike Information Criterion (AIC) and the Schwarz Bayesian Information Criterion (BIC). The Hill models (Hill 4 and Hill 5) were found to be superior in describing the fluoride removal processes due to the sigmoidal nature of the kinetics. Results indicate that the presence of Mn (100 mg L(-1)) and Cd (100 mg L(-1)) respectively increases the rate of fluoride sorption by a factor of ~28.3 and ~10.9, the maximum sorption capacity is increased by ~2.2 and ~1.7. The presence of Ba (100 mg L(-1)) initially inhibited fluoride removal and very poor fits were obtained for all models. Fitting was best described with a biphasic sigmoidal model with the degree of inhibition decreasing with increasing temperature suggesting that at least two processes are involved with fluoride sorption onto natural zeolite in the presence of Ba.

  6. The kinetics of fluoride sorption by zeolite: Effects of cadmium, barium and manganese.

    PubMed

    Cai, Qianqian; Turner, Brett D; Sheng, Daichao; Sloan, Scott

    2015-01-01

    Industrial wastewaters often consist of a complex chemical cocktail with treatment of target contaminants complicated by adverse chemical reactions. The impact of metal ions (Cd(2+), Ba(2+) and Mn(2+)) on the kinetics of fluoride removal from solution by natural zeolite was investigated. In order to better understand the kinetics, the pseudo-second order (PSO), Hill (Hill 4 and Hill 5) and intra-particle diffusion (IPD) models were applied. Model fitting was compared using the Akaike Information Criterion (AIC) and the Schwarz Bayesian Information Criterion (BIC). The Hill models (Hill 4 and Hill 5) were found to be superior in describing the fluoride removal processes due to the sigmoidal nature of the kinetics. Results indicate that the presence of Mn (100 mg L(-1)) and Cd (100 mg L(-1)) respectively increases the rate of fluoride sorption by a factor of ~28.3 and ~10.9, the maximum sorption capacity is increased by ~2.2 and ~1.7. The presence of Ba (100 mg L(-1)) initially inhibited fluoride removal and very poor fits were obtained for all models. Fitting was best described with a biphasic sigmoidal model with the degree of inhibition decreasing with increasing temperature suggesting that at least two processes are involved with fluoride sorption onto natural zeolite in the presence of Ba. PMID:25909159

  7. Characterization and adsorption properties of a lanthanum-loaded magnetic cationic hydrogel composite for fluoride removal.

    PubMed

    Dong, Shuoxun; Wang, Yili

    2016-01-01

    In this study, a novel lanthanum-loaded magnetic cationic hydrogel (MCH-La) was synthesized for fluoride adsorption from drinking water. The adsorption kinetics, isotherms, and effects of pH and co-existing anions on fluoride uptake by MCH-La were evaluated. FTIR, Raman and XPS were used to analyze the fluoride adsorption mechanism of MCH-La. Results showed that MCH-La had positive zeta potential values of 23.6-8.0 mV at pH 3.0-11.0, with the magnitude of saturation magnetization up to 10.3 emu/g. The fluoride adsorption kinetics by MCH-La fitted well with the fractal-like-pseudo-second-order model, and the adsorption capacity reached 93% of the ultimate adsorption capacity within the first 10 min. The maximum fluoride adsorption capacity for MCH-La was 136.78 mg F(-)/g at an equilibrium fluoride concentration of 29.3 mg/L and pH 7.0. Equilibrium adsorption data showed that the Sips model was more suitable than the Langmuir and Freundlich models. MCH-La still had more than 100 mg of F(-)/g adsorption capacity at a strongly alkaline solution (pH > 10). The adsorption process was highly pH-dependent, and the optimal adsorption was attained at pH 2.8-4.0, corresponding to ligand exchange, electrostatic interactions, and Lewis acid-base interactions. With the exception of both anions of HCO3(-) and SiO4(4-), Cl(-), NO3(-), and SO4(2-) did not evidently prevent fluoride removal by MCH-La at their real concentrations in natural groundwater. The fluoride adsorption capacity of the regenerated MCH-La approached 70% of the fresh MCH-La from the second to fifth recycles. FTIR and Raman spectra revealed that C-O and CO functional groups on MCH contributed to the fluoride adsorption, this finding was also confirmed by the XPS F 1s spectra. Deconvolution of C 1s spectra before and after fluoride adsorption indicated that the carboxyl, anhydride, and phenol groups of MCH were involved in the fluoride removal.

  8. In situ AFM crystal growth and dissolution study of calcite in the presence of aqueous fluoride

    NASA Astrophysics Data System (ADS)

    Vavouraki, A.; Putnis, C. V.; Putnis, A.; Koutsoukos, P. G.

    2009-04-01

    Fluoride is naturally abundant, encountered in rocks, soil and fresh and ocean water. Calcite crystals, during crystal growth may incorporate fluoride ions into their lattice (Okumura et al., 1983). In situ atomic force microscopy (AFM) has been used to study the growth and dissolution of calcite {104} surfaces in aqueous solutions in the presence of fluoride, using a fluid cell in which the supersaturated and the understaturated solutions respectively, flow over a freshly cleaved calcite crystal. For growth experiments, supersaturation index (S.I.) with respect to calcite was equal to 0.89 and the initial solution pH 10.2. The crystal growth rates were measured from the closure of the rhombohedral etch pits along the [010] direction induced by an initial dissolution step using pure water. The spreading rate of 2-dimensional nuclei was also measured along the same direction. In the presence of low fluoride concentrations (≤0.33 mM), the crystal growth rate of calcite was unaffected. At higher concentrations (up to 5 mM) growth rate decreased substantially to 50% of the rate in the absence of fluoride. Potential fluoride sorption over the calcite surface may ascribe the decrease of growth rates. Dissolution experiments were conducted at pH= 7.2 and dissolution rates of calcite were measured from the spreading of rhombohedral etch pits along both [010] and [42] directions. The presence of low concentrations of fluoride (≤1.1 mM) in the undersaturated solutions enhanced the dissolution rate along the [42] direction by 50% in comparison with pure water. The morphology of rhombohedral etch pits changed to hexagonal in the presence of fluoride in the undersaturated solutions. The AFM dissolution experiments suggested that the fluoride ions adsorbed onto the calcite surface. Further increase of fluoride concentrations (up to 1.6 mM) resulted in the decrease of the calcite dissolution rate by 60% in both [010] and [42] directions. Reference: Okumura, M, Kitano, Y

  9. Blood lead concentrations in children and method of water fluoridation in the United States, 1988-1994.

    PubMed

    Macek, Mark D; Matte, Thomas D; Sinks, Thomas; Malvitz, Dolores M

    2006-01-01

    Some have hypothesized that community water containing sodium silicofluoride and hydrofluosilicic acid may increase blood lead (PbB) concentrations in children by leaching of lead from water conduits and by increasing absorption of lead from water. Our analysis aimed to evaluate the relation between water fluoridation method and PbB concentrations in children. We used PbB concentration data (n=9,477) from the Third National Health and Nutrition Examination Survey (1988-1994) for children 1-16 years of age, merged with water fluoridation data from the 1992 Fluoridation Census. The main outcome measure was geometric mean PbB concentration, and covariates included age, sex, race/ethnicity, poverty status, urbanicity, and length of time living in residence. Geometric mean PbB concentrations for each water fluoridation method were 2.40 microg/dL (sodium silicofluoride), 2.34 microg/dL (hydrofluosilicic acid), 1.78 microg/dL (sodium fluoride), 2.24 microg/dL (natural fluoride and no fluoride), and 2.14 microg/dL (unknown/mixed status). In multiple linear and logistic regression, there was a statistical interaction between water fluoridation method and year in which dwelling was built. Controlling for covariates, water fluoridation method was significant only in the models that included dwellings built before 1946 and dwellings of unknown age. Across stratum-specific models for dwellings of known age, neither hydrofluosilicic acid nor sodium silicofluoride were associated with higher geometric mean PbB concentrations or prevalence values. Given these findings, our analyses, though not definitive, do not support concerns that silicofluorides in community water systems cause higher PbB concentrations in children. Current evidence does not provide a basis for changing water fluoridation practices, which have a clear public health benefit.

  10. Altered calcium signaling in cancer cells.

    PubMed

    Stewart, Teneale A; Yapa, Kunsala T D S; Monteith, Gregory R

    2015-10-01

    It is the nature of the calcium signal, as determined by the coordinated activity of a suite of calcium channels, pumps, exchangers and binding proteins that ultimately guides a cell's fate. Deregulation of the calcium signal is often deleterious and has been linked to each of the 'cancer hallmarks'. Despite this, we do not yet have a full understanding of the remodeling of the calcium signal associated with cancer. Such an understanding could aid in guiding the development of therapies specifically targeting altered calcium signaling in cancer cells during tumorigenic progression. Findings from some of the studies that have assessed the remodeling of the calcium signal associated with tumorigenesis and/or processes important in invasion and metastasis are presented in this review. The potential of new methodologies is also discussed. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

  11. Vitamin D-enhanced duodenal calcium transport.

    PubMed

    Wongdee, Kannikar; Charoenphandhu, Narattaphol

    2015-01-01

    For humans and rodents, duodenum is a very important site of calcium absorption since it is exposed to ionized calcium released from dietary complexes by gastric acid. Calcium traverses the duodenal epithelium via both transcellular and paracellular pathways in a vitamin D-dependent manner. After binding to the nuclear vitamin D receptor, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] upregulates the expression of several calcium transporter genes, e.g., TRPV5/6, calbindin-D9k, plasma membrane Ca(2+)-ATPase1b, and NCX1, thereby enhancing the transcellular calcium transport. This action has been reported to be under the regulation of parathyroid-kidney-intestinal and bone-kidney-intestinal axes, in which the plasma calcium and fibroblast growth factor-23 act as negative feedback regulators, respectively. 1,25(OH)2D3 also modulates the expression of tight junction-related genes and convective water flow, presumably to increase the paracellular calcium permeability and solvent drag-induced calcium transport. However, vitamin D-independent calcium absorption does exist and plays an important role in calcium homeostasis under certain conditions, particularly in neonatal period, pregnancy, and lactation as well as in naturally vitamin D-impoverished subterranean mammals.

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

    PubMed

    Death, Clare; Coulson, Graeme; Kierdorf, Uwe; Kierdorf, Horst; Morris, William K; Hufschmid, Jasmin

    2015-11-15

    Particulate and gaseous fluoride emissions contaminate vegetation near fluoride-emitting industries, potentially impacting herbivorous wildlife in neighboring areas. Dental fluorosis has been associated with consumption of fluoride-contaminated foliage by juvenile livestock and wildlife in Europe and North America. For the first time, we explored the epidemiology and comparative pathology of dental fluorosis in Australian marsupials residing near an aluminium smelter. Six species (Macropus giganteus, Macropus rufogriseus, Wallabia bicolor, Phascolarctos cinereus, Trichosurus vulpecula, Pseudocheirus peregrinus) demonstrated significantly higher bone fluoride levels in the high (n=161 individuals), compared to the low (n=67 individuals), fluoride areas (p<0.001). Necropsy examinations of all six species from the high-fluoride area near the smelter revealed dental lesions considered characteristic of dental fluorosis in eutherian mammals. Within the high-fluoride area, 67% of individuals across the six species showed dental enamel lesions, compared to 3% in the low-fluoride areas. Molars that erupted before weaning were significantly less likely to display pathological lesions than those developing later, and molars in the posterior portion of the dental arcade were more severely fluorotic than anterior molars in all six species. The severity of dental lesions was positively associated with increasing bone fluoride levels in all species, revealing a potential biomarker of excess fluoride exposure.

  13. Fluoride-containing bioactive glasses: Glass design, structure, bioactivity, cellular interactions, and recent developments.

    PubMed

    Shah, Furqan A

    2016-01-01

    Bioactive glasses (BGs) are known to bond to both hard and soft tissues. Upon exposure to an aqueous environment, BG undergoes ion exchange, hydrolysis, selective dissolution and precipitation of an apatite layer on their surface, which elicits an interfacial biological response resulting in bioactive fixation, inhibiting further dissolution of the glass, and preventing complete resorption of the material. Fluorine is considered one of the most effective in-vivo bone anabolic factors. In low concentrations, fluoride ions (F(-)) increase bone mass and mineral density, improve the resistance of the apatite structure to acid attack, and have well documented antibacterial properties. F(-) ions may be incorporated into the glass in the form of calcium fluoride (CaF2) either by part-substitution of network modifier oxides, or by maintaining the ratios of the other constituents relatively constant. Fluoride-containing bioactive glasses (FBGs) enhance and control osteoblast proliferation, differentiation and mineralisation. And with their ability to release fluoride locally, FBGs make interesting candidates for various clinical applications, dentinal tubule occlusion in the treatment of dentin hypersensitivity. This paper reviews the chemistry of FBGs and the influence of F(-) incorporation on the thermal properties, bioactivity, and cytotoxicity; and novel glass compositions for improved mechanical properties, processing, and bioactive potential.

  14. Fluoride-containing bioactive glasses: Glass design, structure, bioactivity, cellular interactions, and recent developments.

    PubMed

    Shah, Furqan A

    2016-01-01

    Bioactive glasses (BGs) are known to bond to both hard and soft tissues. Upon exposure to an aqueous environment, BG undergoes ion exchange, hydrolysis, selective dissolution and precipitation of an apatite layer on their surface, which elicits an interfacial biological response resulting in bioactive fixation, inhibiting further dissolution of the glass, and preventing complete resorption of the material. Fluorine is considered one of the most effective in-vivo bone anabolic factors. In low concentrations, fluoride ions (F(-)) increase bone mass and mineral density, improve the resistance of the apatite structure to acid attack, and have well documented antibacterial properties. F(-) ions may be incorporated into the glass in the form of calcium fluoride (CaF2) either by part-substitution of network modifier oxides, or by maintaining the ratios of the other constituents relatively constant. Fluoride-containing bioactive glasses (FBGs) enhance and control osteoblast proliferation, differentiation and mineralisation. And with their ability to release fluoride locally, FBGs make interesting candidates for various clinical applications, dentinal tubule occlusion in the treatment of dentin hypersensitivity. This paper reviews the chemistry of FBGs and the influence of F(-) incorporation on the thermal properties, bioactivity, and cytotoxicity; and novel glass compositions for improved mechanical properties, processing, and bioactive potential. PMID:26478431

  15. Arsenic and fluoride removal from groundwater by electrocoagulation using a continuous filter-press reactor.

    PubMed

    Guzmán, Athziri; Nava, José L; Coreño, Oscar; Rodríguez, Israel; Gutiérrez, Silvia

    2016-02-01

    We investigated simultaneous arsenic and fluoride removal from ground water by electrocoagulation (EC) using aluminum as the sacrificial anode in a continuous filter-press reactor. The groundwater was collected at a depth of 320 m in the Bajío region in Guanajuato Mexico (arsenic 43 µg L(-1), fluoride 2.5 mg L(-1), sulfate 89.6 mg L(-1), phosphate 1.8 mg L(-1), hydrated silica 112.4 mg L(-1), hardness 9.8 mg L(-1), alkalinity 31.3 mg L(-1), pH 7.6 and conductivity 993 µS cm(-1)). EC was performed after arsenite was oxidized to arsenate by addition of 1 mg L(-1) hypochlorite. The EC tests revealed that at current densities of 4, 5 and 6 mA cm(-2) and flow velocities of 0.91 and 1.82 cm s(-1), arsenate was abated and residual fluoride concentration satisfies the WHO standard (CF < 1.5 mg L(-1)). Spectrometric analyses performed on aluminum flocs indicated that these are mainly composed of aluminum-silicates of calcium and magnesium. Arsenate removal by EC involves adsorption on aluminum flocs, while fluoride replaces a hydroxyl group from aluminum aggregates. The best EC was obtained at 4 mA cm(-2) and 1.82 cm s(-1) with electrolytic energy consumption of 0.34 KWh m(-3). PMID:26583293

  16. Alternatives to fluoride in the prevention and treatment of dental erosion.

    PubMed

    Buzalaf, Marília Afonso Rabelo; Magalhães, Ana Carolina; Wiegand, Annette

    2014-01-01

    In recent years, different agents have been discussed as potential alternatives to fluoride in the prevention of dental erosion. These agents are intended to form acid-resistant layers on the surface, to induce repair of eroded lesions by mineral precipitation or to prevent the enzymatic degradation of demineralised collagen. The application of adhesives and/or fissure sealants is considered to be an effective alternative to fluoride, but requires professional application and, depending on the product used, a re-sealing of the surface every several months. Studies testing film-forming products, such as polymers, have suggested the potential effectiveness of some of these approaches, such as chitosan, although further studies are needed to confirm the effectiveness of this approach. Other studies have demonstrated that products designed to deliver calcium and/or phosphate have not been successful at providing a significant anti-erosive effect. In advanced erosive lesions, the demineralised collagenous dentine matrix can be degraded by host enzymes such as matrix metalloproteinases (MMPs). As well as fluorides, epigallocatechin gallate and chlorhexidine have been identified as effective MMP inhibitors, with the potential to reduce the progression of dentine erosion. While fluoride compounds have been shown to have an anti-erosive potential, particularly those containing tin, alternative approaches that provide even greater protective capacity still need to be developed and proven to be effective.

  17. Effects of fluoride on screech owl reproduction: Teratological evaluation, growth, and blood chemistry in hatchlings

    USGS Publications Warehouse

    Hoffman, D.J.; Pattee, O.H.; Wiemeyer, Stanley N.

    1985-01-01

    The effects on reproduction in screech owls (Otus asio) of chronic dietary sodium fluoride administration at 0, 40, and 200 ppm were examined. Fluoride at 40 ppm resulted in a significantly smaller egg volume, while 200 ppm also resulted in lower egg weights and lengths. Day-one hatchlings in the 200 ppm group weighed almost 10% less than controls and had shorter crown-rump lengths. No gross abnormalities were apparent. Skeletal clearing and staining revealed significantly shorter tibiotarsus lengths in the 40 ppm and 200 ppm groups and a shorter radius-ulna length in the 200 ppm group. By 7 days of age, body weights and lengths did not differ from controls, but the tibiotarsus in the 200 ppm group remained shorter. No significant differences were detected in hematocrit, hemoglobin, plasma calcium or alkaline phosphatase. Plasma phosphorus levels were higher in the 40 ppm group than in controls. These results, in combination with the findings of Pattee et al. [25], revealed significant impairment of overall reproduction, suggesting that sodium fluoride could cause slight to moderate reproduction disorders in owls in fluoride-polluted areas.

  18. Arsenic and fluoride removal from groundwater by electrocoagulation using a continuous filter-press reactor.

    PubMed

    Guzmán, Athziri; Nava, José L; Coreño, Oscar; Rodríguez, Israel; Gutiérrez, Silvia

    2016-02-01

    We investigated simultaneous arsenic and fluoride removal from ground water by electrocoagulation (EC) using aluminum as the sacrificial anode in a continuous filter-press reactor. The groundwater was collected at a depth of 320 m in the Bajío region in Guanajuato Mexico (arsenic 43 µg L(-1), fluoride 2.5 mg L(-1), sulfate 89.6 mg L(-1), phosphate 1.8 mg L(-1), hydrated silica 112.4 mg L(-1), hardness 9.8 mg L(-1), alkalinity 31.3 mg L(-1), pH 7.6 and conductivity 993 µS cm(-1)). EC was performed after arsenite was oxidized to arsenate by addition of 1 mg L(-1) hypochlorite. The EC tests revealed that at current densities of 4, 5 and 6 mA cm(-2) and flow velocities of 0.91 and 1.82 cm s(-1), arsenate was abated and residual fluoride concentration satisfies the WHO standard (CF < 1.5 mg L(-1)). Spectrometric analyses performed on aluminum flocs indicated that these are mainly composed of aluminum-silicates of calcium and magnesium. Arsenate removal by EC involves adsorption on aluminum flocs, while fluoride replaces a hydroxyl group from aluminum aggregates. The best EC was obtained at 4 mA cm(-2) and 1.82 cm s(-1) with electrolytic energy consumption of 0.34 KWh m(-3).

  19. Bond strength of a fluoride-releasing bracket adhesive. Experimental study.

    PubMed

    Graf, I; Breier, M; Huck, L; Schwarze, C W

    1999-01-01

    The aim of the study was to examine a new fluoride-releasing light-cured filling composite for its bonding and debonding qualities when used as a bracket adhesive. The material investigated was a hybrid composite containing a chemically modified fluoride apatite, which is claimed to provide the enamel with phosphate, calcium, and fluoride ions in the presence of an acid pH, recharging its resources of these ions through fluoride-containing toothpastes used in daily oral hygiene. Concurrently suitability as an enamel conditioner was tested in a new self-etching primer, which does not require water rinsing but is gently air dried instead. For comparison a conventional light-cure single-component adhesive was used together with 37% orthophosphoric acid. After application of the respective conditioners, mesh-backed metal brackets were bonded to 20 human premolars in each of the 2 adhesive groups and subjected to a shear test. Bond failure location was evaluated using the Adhesive Remnant Index (ARI). Average bond strength of the experimental bracket adhesive and the conventional etchant was 8.96 MPa. Conditioning with the self-etching primer led to a decrease of mean shear bond strength values to 6.55 MPa. Highest bond strength was determined in the control group (12.19 MPa). The bond strength results obtained in the shear test recommend the new material as a bracket adhesive to be used with orthophosphoric acid for etching. PMID:10028788

  20. Co-substitution of carbonate and fluoride in hydroxyapatite: Effect on substitution type and content

    NASA Astrophysics Data System (ADS)

    Zhu, Qing-Xia; Li, Ya-Ming; Han, Dan

    2015-04-01

    The nanosized hydroxyapatite substituted by fluoride and carbonate ions (CFHA) had been synthesized by aqueous precipitation method. CFHA had been considered as potential bone graft material for orthopedic and dental applications. The objective of this study was to determine the effects of simultaneously incorporated CO{3/2-} and F- on the substitution type and content. The morphologies of CFHAs were observed by TEM. The carbonate substitution type and content were characterized by FTIR. The fluoride contents were determined by F-selective electrode. The phase compositions and crystallinity of the samples were investigated by XRD. The fluoride and carbonate contents of CFHA increase with the dopant concentrations nonlinearly. The carbonate substitution has much more obvious effect on morphology compared with the fluoride substitution. The co-existence of CO{3/2-} and F- ions can influence the corresponding substitution fraction. The isomorphic substitution of sodium for calcium in the substitution process of CO{3/2-} can improve crystal degree and favor the B-type substitutions. Due to the closeness of the ion radii and equivalent substitution of F- and OH-, F- will occupy the OH- sites of HA crystals more easily, compelling most of the CO{3/2-} to be located in the B sites.

  1. 21 CFR 872.6870 - Disposable fluoride tray.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Disposable fluoride tray. 872.6870 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6870 Disposable fluoride tray. (a) Identification. A disposable fluoride tray is a device made of styrofoam intended to apply fluoride topically...

  2. 21 CFR 872.6870 - Disposable fluoride tray.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Disposable fluoride tray. 872.6870 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6870 Disposable fluoride tray. (a) Identification. A disposable fluoride tray is a device made of styrofoam intended to apply fluoride topically...

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

    ERIC Educational Resources Information Center

    Rebich, Theodore, Jr.; And Others

    1982-01-01

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

  4. Fluoridation and Defluoridation. Training Module 2.230.2.77.

    ERIC Educational Resources Information Center

    McMullen, L. D.

    This document is an instructional module package prepared in objective form for use by an instructor familiar with fluoridation and fluoride feeding equipment. Enclosed are objectives, an instructor guide, student handouts and transparency masters. The module considers the principles and purposes of fluoridation, methods of feeding fluoride,…

  5. Optical and mechanical properties of thermally evaporated fluoride thin films

    SciTech Connect

    Zhang, K.; Fahey, R.; Jasinski, D.; Scarpino, C.; Dziendziel, R.; Burger, S.; DePoy, D.

    1998-06-08

    As a result of health and safety issues surrounding the use of radioactive materials on coated optical components, there has been renewed interest in coating materials whose optical and mechanical properties approach those offered by their radioactive counterparts. Due to the radioactive nature of ThF{sub 4} and its widespread use in optical coatings, the coating industry is examining other low index and non-radioactive fluorides as possible alternatives. In this paper, the authors present the results of an experimental study on the optical and mechanical properties of thermally evaporated ThF{sub 4}, DyF{sub 3}, CeF{sub 3}, LiF, HfF{sub 4}, IRX, and IRB thin films, where the materials were deposited at different substrate temperatures. The objective is to examine this series of fluorides under comparable deposition conditions and with respect to such material properties as: n and k, film stress, and environmental stability. The optical constants of these fluorides were evaluated over the wavelength region from 1.0 {micro}m to 12.5 {micro}m.

  6. Simultaneous measurement of ciliary beating and intracellular calcium.

    PubMed Central

    Korngreen, A; Priel, Z

    1994-01-01

    A novel system for measuring, simultaneously, ciliary beating and intracellular free calcium is presented. The advantages and dynamic nature of the system are demonstrated by measuring the effects of the calcium ionophore lonomycin and of extracellular ATP on ciliated rabbit trachea. The results are discussed with regard to the ciliary and calcium stimulation. PMID:7919010

  7. Low-fluoride dentifrice and gastrointestinal fluoride absorption after meals.

    PubMed

    Cury, J A; Del Fiol, F S; Tenuta, L M A; Rosalen, P L

    2005-12-01

    A low-fluoride (F) dentifrice has been recommended to reduce the risk of dental fluorosis, but its anti-caries efficacy is questionable compared with that of conventional dentrifices (1000-1100 microg F/g). The tested hypothesis was that conventional dentifrices might be safe if used soon after meals, since food interferes with F absorption. In a crossover, double-blind study, 11 volunteers ingested a dentifrice slurry containing 0 (placebo), 550 (low F), or 1100 microg F/g in 3 gastric content situations: on fasting, or 15 min after breakfast or lunch. F was analyzed in saliva and 24-hour urine samples. The conventional dentifrice ingested after lunch resulted in only 10% higher F absorption than the low-F ingested on fasting. Analysis of the data suggests that the risk of fluorosis could be reduced by the use of either a low-F dentifrice or a conventional dentifrice, if toothbrushing occurred soon after meals.

  8. Current status of fluoride volatility method development

    SciTech Connect

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

    2013-07-01

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

  9. [Fluoride-induced nephrotoxicity: factor fiction?].

    PubMed

    Nuscheler, M; Conzen, P; Schwender, D; Peter, K

    1996-02-01

    In the 1960s, the widespread use of the inhalational anaesthetic methoxyflurane was associated with a significant occurrence of postoperative renal dysfunction. This was attributed to hepatic biotransformation of methoxyflurane and subsequent release of inorganic fluoride ions into the circulation. Based upon the clinical experience with methoxyflurane, serum fluoride concentrations exceeding 50 mumol/l were considered to be nephrotoxic. Without further reevaluation, this 50 mumol/l threshold was subsequently applied to other fluorinated anaesthetics as well. Enflurane and even isoflurane may, when used during prolonged operations, also yield anorganic fluoride levels in excess of 50 mumol/l. Nevertheless, no cases of renal dysfunction attributable to prolonged use of these anesthetics have been reported. About 4% of the new inhalational anaesthetic sevoflurane is metabolized, and fluoride concentrations exceeding those after enflurane are frequently measured. Numerous studies have examined the nephrotoxic potential of sevoflurane degradation products. However, fluoride-related toxicity has been observed neither in animal nor in clinical studies, including prolonged administration and patients with pre-existing renal disease. New insights into the intrarenal metabolisation of volatile anaesthetics may well explain the absence of nephrotoxicity after sevoflurane. The threshold for fluoride nephrotoxicity of 50 mumol/l, still given in many medical text-books, can no longer be applied as an indicator of nephrotoxicity after isoflurane, enflurane or sevoflurane. Therefore, the elevated serum fluoride concentrations consistently recorded following anaesthesia with sevoflurane are devoid of clinical significance. PMID:8775101

  10. Evaluation of Effect of Brushite-Calcite and Two Indigenous Herbs in Removal of Fluoride from Water

    PubMed Central

    Naveenkumar, Puvvadi Gopalakrishna; Prashant, Gouder Manjunath; Sakeenabi, Basha; Allamaprabhu; Vijetha, Kothyala

    2016-01-01

    Introduction The acceptable concentration of fluoride in drinking water is 1.5mg/l. Excess fluoride in drinking water causes fluorosis. Fluorosis is an important public health problem in India. Several treatment technologies suggested in the past for removing excess fluoride generated and causes various chemical byproductswhich are hazardous to public. In recent years, there has been a resurgence of interest to use natural materials due to cost and associated health and environmental concerns of synthetic organic polymers and inorganic chemicals. Aim The aim of this study was to evaluate and compare the defluoridating capability of the brushite-calcite with that of two indigenous herbs, tulsi and wheat grass. Materials and Methods One gram of brushite-calcite combination, tulsi and wheat grass were separately added to 10 containers, each containing 1.0 l of prepared distilled water with a fluoride concentration of 5ppm and naturally fluoridated water at 2ppm. Half of the samples were boiled for one minute in a domestic electric kettle for one minute and allowed to cool. The remaining half of the samples was left un-boiled. Fluoride concentration in all the samples was assessed at the end of 30 minutes and 24 hours using fluoride ion selective electrode method. Data was analyzed using unpaired t-test and one-way ANOVA. Results For water with 2ppm and 5ppm fluoride, brushite-calcite had shown highest de-fluoridation capacity (p=0.001) at the end of both 30 minutes and 24 hours in boiled samples whereas tulsi (p=0.001) was most effective in un-boiled samples. Conclusion The results of the study suggest that tulsi can be used for domestic water defluoridation as it is economic, safe and effective. PMID:27504417

  11. Deposition of fluoride on enamel surfaces released from varnishes is limited to vicinity of fluoridation site

    PubMed Central

    Lennon, A. M.; Yakin, M.; Becker, K.; Buchalla, W.; Attin, R.; Wiegand, A.

    2006-01-01

    The aim of the in-situ study was to determine fluoride uptake in non-fluoridated, demineralized enamel after application of fluoride varnishes on enamel samples located at various distances from the non-fluoridated samples. All enamel samples used were demineralized with acidic hydroxyethylcellulose before the experiment. Intra-oral appliances were worn by ten volunteers in three series: (1, Mirafluorid, 0.15% F; 2, Duraphat, 2.3% F and 3, unfluoridated controls) of 6 days each. Each two enamel samples were prepared from 30 bovine incisors. One sample was used for the determination of baseline fluoride content (BFC); the other was treated according to the respective series and fixed in the intra-oral appliance for 6 days. Additionally, from 120 incisors, each four enamel samples were prepared (one for BFC). Three samples (a–c) were placed into each appliance at different sites: (a) directly neighboured to the fluoridated specimen (=next), (b) at 1-cm distance (=1 cm) and (c) in the opposite buccal aspect of the appliance (=opposite). At these sites, new unfluoridated samples were placed at days 1, 3 and 5, which were left in place for 1 day. The volunteers brushed their teeth and the samples with fluoridated toothpaste twice per day. Both the KOH-soluble and structurally bound fluoride were determined in all samples to determine fluoride uptake and were statistically analyzed. One day, after fluoridation with Duraphat, KOH-soluble fluoride uptake in specimen a (=next) was significantly higher compared to the corresponding samples of both the control and Mirafluorid series, which in turn were not significantly different from each other. At all other sites and time points, fluoride uptake in the enamel samples were not different from controls for both fluoride varnishes. Within the first day after application, intra-oral-fluoride release from the tested fluoride varnish Duraphat leads to KOH-soluble fluoride uptake only in enamel samples located in close

  12. Preparation and characterization of γ-AlOOH @CS magnetic nanoparticle as a novel adsorbent for removing fluoride from drinking water.

    PubMed

    Wan, Zhen; Chen, Wei; Liu, Cheng; Liu, Yu; Dong, Changlong

    2015-04-01

    For this study, a novel adsorbent of γ-AlOOH @CS (pseudoboehmite and chitosan shell) magnetic nanoparticles (ACMN) with magnetic separation capabilities was developed to remove fluoride from drinking water. The adsorbent was first characterized, and then its performance in removing fluoride was evaluated. Kinetic data demonstrated rapid fluoride adsorption with more than 80% fluoride adsorption within the initial 20 min and equilibrium reached in 60 min. Based on the results of kinetic and isotherm models, the fluoride adsorption process on the ACMN's surface was a monolayer adsorption on a homogeneous surface. Thermodynamic parameters presented that the adsorption process is spontaneous and endothermic in nature. The mechanism for the adsorption involved electrostatic interaction and hydrogen bonding. Moreover, the calculated adsorption capacity of the ACMN for fluoride using the Langmuir model was 67.5 mg/g (20°C, pH=7.0±0.1), higher than other fluoride removal adsorbents. This nanoadsorbent performed well over a pH range of 4-10. The study found that PO4(3-) was the co-existing anion most able to hinder the nanoparticle's fluoride adsorption, followed by NO3(-) then Cl(-). Experimental results suggest that ACMN is a promising adsorbent for treating fluoride-contaminated water.

  13. Experimental evaluation of sorptive removal of fluoride from drinking water using iron ore

    NASA Astrophysics Data System (ADS)

    Kebede, Beekam; Beyene, Abebe; Fufa, Fekadu; Megersa, Moa; Behm, Michael

    2016-03-01

    High concentrations of fluoride in drinking water is a public health concern globally and of critical importance in the Rift Valley region. As a low-cost water treatment option, the defluoridation capacity of locally available iron ore was investigated. Residence time, pH, agitation rate, particle size of the adsorbent, sorbent dose, initial fluoride concentration and the effect of co-existing anions were assessed. The sorption kinetics was found to follow pseudo-first-order rate and the experimental equilibrium sorption data fitted reasonably well to the Freundlich model. The sorption capacity of iron ore for fluoride was 1.72 mg/g and the equilibrium was attained after 120 min at the optimum pH of 6. The sorption study was also carried out at natural pH conditions using natural ground water samples and the fluoride level was reduced from 14.22 to 1.17 mg/L (below the WHO maximum permissible limit). Overall, we concluded that iron ore can be used in water treatment for fluoride removal in the Rift Valley region and beyond.

  14. Quantification of fluoride in food by microwave acid digestion and fluoride ion-selective electrode.

    PubMed

    Rocha, René A; Rojas, Dayana; Clemente, María Jesús; Ruiz, Antonio; Devesa, Vicenta; Vélez, Dinoraz

    2013-11-13

    To quantify fluoride in food it is necessary to extract the fluoride from the matrix. Dry ashing (alkali fusion) and facilitated diffusion are the methods most commonly used, but their application requires lengthy treatments. The present study proposes the use of a microwave oven and 7 mol/L nitric acid for simple, rapid digestion of foods for fluoride analysis. The analyte is subsequently quantified by fluoride ion-selective electrode. The various steps of the method were optimized and an in-house validation was performed. The limit of quantification (0.130 mg/kg), trueness (92%), recovery (84-101%), and precision (1-8%) were determined. These analytical characteristics are satisfactory and show the suitability of the method for analysis of fluoride in foods of various kinds. The method's ease of application and the use of equipment normally found in food analysis laboratories may help to further increase research on fluoride concentrations in foods consumed by the population.

  15. Fluoride concentration in drinking water of Karachi city (Pakistan).

    PubMed

    Siddique, Azhar; Mumtaz, Majid; Saied, Sumayya; Karim, Zahida; Zaigham, Nayyer A

    2006-09-01

    The ground and municipal water supply samples of Karachi city were analyzed for their fluoride contents. The fluoride contents in water samples collected from the subsurface and river sources were found below the WHO recommended value for the general health of the people. However, in some industrial areas the groundwater sample showed higher level of fluoride concentration. Continuous monitoring of water resources and cautious fluoridation is suggested to maintain proper status of fluoride concentration in the drinking water.

  16. PROCESS FOR TREATING VOLATILE METAL FLUORIDES

    DOEpatents

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

    1957-10-01

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

  17. The effect of fluoride impregnated dental floss on enamel fluoride uptake in vitro and streptococcus mutans colonization in vivo.

    PubMed

    Chaet, R; Wei, S H

    1977-01-01

    The conclusions reached from this investigation can be summarized as follows: Fluoride can be incorporated into unwaxed dental floss. Placement of the fluoride impregnated dental floss in acid-buffer solution results in the release of most of the fluoride in the floss. Interproximal surfaces of teeth treated in vitro with fluoride impregnated dental floss acquired significantly (approximately three fold) more enamel fluoride than those treated with plain dental floss. The number of in vivo interproximal areas harboring Streptococcus mutans was reduced significantly after treatment with fluoride impregnated dental floss. Further studies should be done to establish the biological, physiochemical, manufacturing, and practical aspects of fluoride impregnated dental floss.

  18. Polymeric Membrane Electrodes with Improved Fluoride Selectivity and Lifetime Based on Zr(IV)- and Al(III)- Tetraphenylporphyrin Derivatives

    PubMed Central

    Pietrzak, Mariusz; Meyerhoff, Mark E.; Malinowska, Elżbieta

    2007-01-01

    Novel aluminum(III)- and zirconium(IV)-tetraphenylporhyrin (TPP) derivatives are examined as fluoride selective ionophores for preparing polymer membrane-based ion-selective electrodes (ISEs). The influence of t-butyl— or dichloro— phenyl ring substituents as well as the nature of the metal ion center (Al(III) vs. Zr(IV)) on the anion complexation constants of TPP derivative ionophores are reported. The anion binding stability constants of the ionophores are characterized by the so-called “sandwich membrane” method. All of the metalloporphyrins examined form their strongest anion complexes with fluoride. The influence of plasticizer as well as the type of lipophilic ionic site additive and their amounts in the sensing membrane are discussed. It is shown that membrane electrodes formulated with the metalloporphyrin derivatives and appropriate anionic or cationic additives exhibit enhanced potentiometric response toward fluoride over all other anions tested. Since selectivity toward fluoride is enhanced in the presence of both anionic and cationic additives, the metalloporphyrins can function as either charged or neutral carriers within the organic membrane phase. In contrast to previously reported fluoride-selective polymeric membrane electrodes based on metalloporphyrins, nernstian or near-nernstian (−51.2 to −60.1 mV decade−1) as well as rapid (t < 80s) and fully reversible potentiometric fluoride responses are observed. Moreover, use of aluminum(III)—t-butyltetraphenylporphyrin as the ionophore provides fluoride sensors with prolonged (7 months) functional life-time. PMID:17631098

  19. Containerless processing of fluoride glass

    NASA Technical Reports Server (NTRS)

    Doremus, Robert H.

    1990-01-01

    Ground-based experiments on glass formation, crystallization, surface tension, vaporization, and chemical durability of a zirconium-barium-lanthanum (ZBL) fluoride glass are summarized. In a container large, columnar grains grew out from the container-glass interface during cooling. The main crystalline phase was alpha BaZrF6. A ZBL glass sphere was levitated acoustically during Shuttle flight STS-11. The glass was melted and then cooled while being levitated (containerless). Crystallization in the recovered sample was very fine and mainly beta BaZr2F10, showing the influence of the container on the nucleation and microstructure of crystallization in the glass. Glass formation should be easier for a containerless glass than in a container.

  20. Fluoride content in plaque solids and fluid after ingestion of fluoridated milk.

    PubMed

    Martínez-Mier, Esperanza A; Soto-Rojas, Armando E; Buckley, Christine; Weitz, Andrea; Villa, Alberto; Zero, Domenick T

    2013-09-01

    This study explored differences in dental biofilm solids and fluid fluoride after ingestion of NaF or Na2FPO3 in milk or non-fluoridated milk. Eighteen volunteers ingested 1 mg fluoride in 200 mL of milk or 200 mL of non-fluoridated milk. Biofilm samples were collected at baseline, 30, 60, and 240 min and biofilm solids and fluid were micro-analyzed for fluoride. Analysis of variance was performed and the total delivery, retention, and clearance of fluoride to biofilm solids and fluid were estimated as the area under the curve between 0 and 240 min. No statistically significant differences were found for baseline values. Biofilm fluid fluoride values ranged from 0.11 ± 0.05 to 0.21 ± 0.08 µg F/mL while biofilm solid values ranged from 0.62 ± 0.39 to 1.75 ± 1.16 µg F/g. Biofilm fluid values were significantly lower at 60 min for Na2FPO3 in milk. Clearance profiles for biofilm fluid diverged after the initial 60 min. Na2FPO3 had a smaller area under the curve from 60 to 240 min than NaF. Results of this study indicate that the release and clearance of fluoride in biofilm vary among fluoridation compounds and that the concentrations in biofilm solids and fluid also vary and are not correlated to each other in many cases.

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

    PubMed

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

    2016-01-01

    With increased awareness of the health benefits of the compounds in green tea, especially polyphenols, its consumption is rising. The main purpose of this study is to determine the effect of different additives on the released fluoride into tea liquor and also daily fluoride intake. The concentrations of fluoride, nitrate, sulfate, and chloride were measured in 15 different flavored green teas (Refah-Lahijan). The fluoride and other anion concentrations were measured by ion chromatography method. The data were analyzed with Statistical Package for the Social Sciences version 16.0. The results showed that the minimum and maximum concentrations of fluoride in the green tea infusions were 0.162 mg/L (cinnamon-flavored green tea) and 3.29 mg/L (bagged peach-flavored green tea), respectively. The mean concentration of fluoride in the green tea leaves was 52 mg/kg, and approximately 89% of the fluoride was released from the green tea leaves into the infusions after brewing. The fluoride concentrations varied significantly among the examined green teas (P < 0.05). However, the additives had no significant effect on the fluoride release into the infusions (P > 0.05). Finally, drinking of the studied green teas cannot make a significant contribution to the daily dietary intake of F for consumers. PMID:27042093

  2. Effects of treatment with sodium fluoride and subsequent starvation on fluoride content of earthworms

    SciTech Connect

    Walton, K.C.

    1987-01-01

    The two experiments described here originated during a long-term investigation into the occurrence and movement of pollutant fluoride in a terrestrial ecosystem. Moles (Talpa europaea) whose diet consist largely of various species of earthworm Lumbricidae, are one of the species under investigation. Bone fluoride in moles was found to be higher, on average, than in foxes or small rodents. Moles probably acquire fluoride from their earthworm diet. Earthworms do not have any readily identifiable tissue in which to store large amounts of fluoride but, for their size, they have a considerable amount of soil in their gut, up oto 20% of their dry weight. Preliminary measurements of fluoride in whole earthworms suggested that observed levels could probably be accounted for by fluoride bound in the mineral part of contained soil and released during preparatory ashing. Two experiments to investigate this situation are described; here their aims were: to expose earthworms kept in soil to different concentrations of sodium fluoride; to measure resulting fluoride in earthworms when soil was removed from their gut by starvation for varying periods of time; and to compare amounts of fluoride in whole starved earthworms with those in starved earthworms from which remaining soil had also been physically removed by dissection and washing.

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

    PubMed Central

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

    2016-01-01

    With increased awareness of the health benefits of the compounds in green tea, especially polyphenols, its consumption is rising. The main purpose of this study is to determine the effect of different additives on the released fluoride into tea liquor and also daily fluoride intake. The concentrations of fluoride, nitrate, sulfate, and chloride were measured in 15 different flavored green teas (Refah-Lahijan). The fluoride and other anion concentrations were measured by ion chromatography method. The data were analyzed with Statistical Package for the Social Sciences version 16.0. The results showed that the minimum and maximum concentrations of fluoride in the green tea infusions were 0.162 mg/L (cinnamon-flavored green tea) and 3.29 mg/L (bagged peach-flavored green tea), respectively. The mean concentration of fluoride in the green tea leaves was 52 mg/kg, and approximately 89% of the fluoride was released from the green tea leaves into the infusions after brewing. The fluoride concentrations varied significantly among the examined green teas (P < 0.05). However, the additives had no significant effect on the fluoride release into the infusions (P > 0.05). Finally, drinking of the studied green teas cannot make a significant contribution to the daily dietary intake of F for consumers. PMID:27042093

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

    PubMed

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

    2016-01-01

    With increased awareness of the health benefits of the compounds in green tea, especially polyphenols, its consumption is rising. The main purpose of this study is to determine the effect of different additives on the released fluoride into tea liquor and also daily fluoride intake. The concentrations of fluoride, nitrate, sulfate, and chloride were measured in 15 different flavored green teas (Refah-Lahijan). The fluoride and other anion concentrations were measured by ion chromatography method. The data were analyzed with Statistical Package for the Social Sciences version 16.0. The results showed that the minimum and maximum concentrations of fluoride in the green tea infusions were 0.162 mg/L (cinnamon-flavored green tea) and 3.29 mg/L (bagged peach-flavored green tea), respectively. The mean concentration of fluoride in the green tea leaves was 52 mg/kg, and approximately 89% of the fluoride was released from the green tea leaves into the infusions after brewing. The fluoride concentrations varied significantly among the examined green teas (P < 0.05). However, the additives had no significant effect on the fluoride release into the infusions (P > 0.05). Finally, drinking of the studied green teas cannot make a significant contribution to the daily dietary intake of F for consumers.

  5. Inhaled magnesium fluoride reverse bronchospasma.

    PubMed

    Gandia, Fedoua; Rouatbi, Sonia; Latiri, Imed; Guénard, Hervé; Tabka, Zouhair

    2010-01-01

    Asthma is a global health problem. Asthma attacks are becoming more severe and more resistant to usual treatment by beta(2) agonists nebulisation. The search for a new product that could reduce the morbidity of asthmatic disease seems necessary. The objective of this study was to compare the effectiveness of inhaled magnesium fluoride (MgF(2)) with that of magnesium sulphate (MgSO(4)) 15% alone and sodium fluoride (NaF) 0.5 M alone in rats pre-contracted by methacholine (MeCh). Fifty six adult male Wistar rats of medium weight 259 +/- 15 g were divided randomly into five groups. They inhaled respectively: MeCh, MgF(2) + NaCl 0.9%, MgF(2) + acetic acid, MgSO(4) 15% single and NaF (0.5 M) single. Airway resistances were measured after each dose of MeCh by pneumomultitest equipment. Results indicated that (1) MgF(2) + NaCl 0.9%, MgF(2) + acetic acid and MgSO(4) reversed significantly the methacholine-induced bronchial constriction in rats and had a bronchodilating effect at the moment of its administration (2) MgF(2) + acetic acid led to a greater decrease (P<0.05) of bronchial resistances when compared to that obtained from MgF(2) + NaCl 0.9%, NaF exclusively and MgSO(4) alone (3) inhaled NaF alone led to a significant bronchorelaxing effect (P<0.05) that starts at the sixth dose of MeCh (17 mg/L). As a matter of fact, MgF(2) dissolved in acetic acid and delivered in aerosol form reduces significantly bronchial spasm. In conclusion, MgF(2) can be used as a bronchodilator for diseases with bronchospasma such as asthma and chronic obstructive pulmonary disease (COPD).

  6. [Fluoride contents of rat molars following the administration of amine-fluoride-containing caries preventives (author's transl)].

    PubMed

    Novikov, L L; Treide, A; Kolesnik, A G; Novikova, N V; Jacobi, J

    1979-01-01

    Experiments on fifty Wistar rats were conducted with the object of studying the incorporation of fluoride into the enamel of molars subsequent to the administration of amine-fluoride-containing caries preventives. - Use of two toothpastes with low fluoride contents of 0.125% and 0.18% F, respectively, and two higher-fluoride (1% F) solutions resulted in a marked increase in the concentration of fluoride in the superficial layers of dental enamel.

  7. Alterations in biochemical parameters during subacute toxicity of fluoride alone and in conjunction with aluminum sulfate in goats.

    PubMed

    Kant, Vinay; Srivastava, Anil Kumar; Verma, Pawan Kumar; Raina, Rajinder

    2009-07-01

    Fluoride toxicity is a serious health problem in many parts of the globe. In present study, sodium fluoride at 20 mg/kg alone and in conjunction with aluminum sulfate at 150 mg/kg was administered orally daily for 30 days in healthy goats of group 1 and 2, respectively, to access the alterations in the various biochemical parameters during subacute toxicity of fluoride alone and in conjunction with aluminum sulfate. In Group 1, significant alterations in plasma glucose, blood urea nitrogen (BUN), creatinine, total protein, albumin, globulin, albumin/globulin ratio, magnesium, and sodium were observed on different days of exposure from their pre-exposure values. However, no significant changes were observed in plasma calcium, phosphorus, and potassium on different days of exposure of sodium fluoride. Similar type of biochemical alterations were noticed in the goats of Group 2 except BUN, total protein magnesium, and sodium. On the basis of results, it could be concluded that sodium fluoride alone and in conjunction with aluminum sulfate produced significant alterations in the various biochemical parameters of the body.

  8. Alterations in biochemical parameters during subacute toxicity of fluoride alone and in conjunction with aluminum sulfate in goats.

    PubMed

    Kant, Vinay; Srivastava, Anil Kumar; Verma, Pawan Kumar; Raina, Rajinder

    2009-07-01

    Fluoride toxicity is a serious health problem in many parts of the globe. In present study, sodium fluoride at 20 mg/kg alone and in conjunction with aluminum sulfate at 150 mg/kg was administered orally daily for 30 days in healthy goats of group 1 and 2, respectively, to access the alterations in the various biochemical parameters during subacute toxicity of fluoride alone and in conjunction with aluminum sulfate. In Group 1, significant alterations in plasma glucose, blood urea nitrogen (BUN), creatinine, total protein, albumin, globulin, albumin/globulin ratio, magnesium, and sodium were observed on different days of exposure from their pre-exposure values. However, no significant changes were observed in plasma calcium, phosphorus, and potassium on different days of exposure of sodium fluoride. Similar type of biochemical alterations were noticed in the goats of Group 2 except BUN, total protein magnesium, and sodium. On the basis of results, it could be concluded that sodium fluoride alone and in conjunction with aluminum sulfate produced significant alterations in the various biochemical parameters of the body. PMID:19148585

  9. Shock Induced Birefringence in Lithium Fluoride

    SciTech Connect

    Holmes, N C

    2001-06-01

    We have used an ellipsometer to measure the birefringence of lithium fluoride in shock compression experiments. In previous x-ray diffraction experiments, single crystal [100] LiF has been reported to remain cubic at moderate pressures.

  10. Synthesis and characterization of fluoride fluorescent sensor

    NASA Astrophysics Data System (ADS)

    Hijji, Yousef M.; Wairia, Gilbert; Edwards, Achelle; Iwunze, Maurice; Kennedy, Alvin P., Sr.; Williams, Richard J.

    2004-12-01

    Due to the importance of fluoride in clinical treatment of osteoporosis and its toxicity from over accumulation in bones there is an increased interest in developing selective optical methods for the detection of fluoride anion. Anion recognition and sensing are of interest because of their importance in biological environmental assays and efforts are paid for developing sensitive methods. We synthesized salicylidene furfurylamine 1 and studied spectral properties. Compound 1 fluoresced strongly and the fluorescence was strongly enhanced in the presence of anions as fluoride at low concentrations. A substantially red-shifted emission in acetonitrile was observed. The excitation at 390 nm and the emission was observed at 469nm. Fluoride showed strong absorption and fluorescence enhancement with a significant Stokes shift. Acetate, dihydrogen phosphate, showed small effect, while chloride, bromide had no significant effect.

  11. AES analysis of barium fluoride thin films

    NASA Astrophysics Data System (ADS)

    Kashin, G. N.; Makhnjuk, V. I.; Rumjantseva, S. M.; Shchekochihin, Ju. M.

    1993-06-01

    AES analysis of thin films of metal fluorides is a difficult problem due to charging and decomposition of such films under electron bombardment. We have developed a simple algorithm for a reliable quantitative AES analysis of metal fluoride thin films (BaF 2 in our work). The relative AES sensitivity factors for barium and fluorine were determined from BaF 2 single-crystal samples. We have investigated the dependence of composition and stability of barium fluoride films on the substrate temperature during film growth. We found that the instability of BaF 2 films grown on GaAs substrates at high temperatures (> 525°C) is due to a loss of fluorine. Our results show that, under the optimal electron exposure conditions, AES can be used for a quantitative analysis of metal fluoride thin films.

  12. Study of fluoride corrosion of nickel alloys

    NASA Technical Reports Server (NTRS)

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

    1969-01-01

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

  13. Musculoskeletal problems and fluoride exposure: A cross-sectional study among metal smelting workers.

    PubMed

    Saha, A; Mukherjee, A K; Ravichandran, B

    2016-09-01

    Frequent and repetitive activities in job and awkward postures are shown as major contributors of musculoskeletal problems in most of the occupational health studies; however, efforts to explore newer risk factor are important to plan interventional measures. In this backdrop, this study examined contribution of fluoride exposure to musculoskeletal complaints. A cross-sectional interviewer-administered questionnaire survey was conducted involving 180 randomly selected subjects from a metal smelting industry. Clinical examination of the subjects was also performed to assess their health status and morbidity details. Assessment of personal exposure to particulate and gaseous fluoride at workplace was conducted. Urinary fluoride level was also examined in post-shift samples collected from study subjects. The mean age of the study subjects was 39.1 (±6.7) years. Majority of the workers (42.5%) were engaged in pot room. About 54% workers were suffering from backache and 66% subjects had joint pain. Exposure of workers to both particulate and gaseous fluoride and post-working shift urinary fluoride level was significantly higher in pot-room workers in comparison with all other workers. It was observed that age (odds ratio (OR): 1.62; 95% confidence interval (CI): 1.18-2.34), drinking untreated water (OR: 1.51; 95% CI: 1.03-2.76), working in pot room (OR: 1.44; 95% CI: 1.13-1.91) and urinary fluoride level (OR: 2.71; 95% CI: 1.81-3.75) had significant effects on musculoskeletal complaints. This study concludes that along with other predictors such as nature of work, posture at work and age of worker, exposure to fluoride also has significant role in the occurrence of musculoskeletal morbidity.

  14. Growth, feed efficiency and blood profile of buffalo calves consuming high levels of fluoride: growth and blood metabolites in buffaloes fed high fluoride.

    PubMed

    Madan, Jyotsana; Puri, J P; Singh, J K

    2009-03-01

    Twelve male buffalo calves of 10 to 12 months of age were divided into 3 groups of four each. They were fed wheat straw+concentrate mixture +3 Kg greens. The chemical composition of the diet was same in all the three groups except fluoride which was added (as NaF) in concentrate mixture of group B and C to make the final fluoride concentration 30 ppm and 60 ppm respectively. The animals were kept on scheduled diet for a period of 90 days. Body weights were recorded at the start of the experiment and at fortnightly interval thereafter. Analysis of data revealed that the dry matter intake decreased non significantly in group B and C as compared to control group. A significant decrease in serum calcium and a significant increase in phosphorus concentration were observed in group C animals. A significant increase was observed in alkaline phosphatase activity in group C animals. A non significant decrease was observed in T4 values in group C animals. On the basis of these results it could be concluded that fluoride in the diet of buffalo calves @ 30 ppm is a safe level whereas 60 ppm has affected the blood metabolites. PMID:18618286

  15. Materials processing apparatus development for fluoride glass

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  16. APPLICATION OF VACUUM SALT DISTILLATION TECHNOLOGY FOR THE REMOVAL OF FLUORIDE

    SciTech Connect

    Pierce, R.; Pak, D.

    2011-08-10

    activities are concerned with the removal of the halide ions associated with plutonium trifluoride (PuF{sub 3}), plutonium tetrafluoride (PuF{sub 4}), calcium fluoride (CaF{sub 2}), and calcium chloride (CaCl{sub 2}). This report discusses non-radioactive testing of small-scale and pilot-scale systems and radioactive testing of a small-scale system. Experiments focused on demonstrating the chemistry for halide removal and addressing the primary engineering questions associated with a change in the process chemistry.

  17. The future of fluorides and other protective agents in erosion prevention.

    PubMed

    Lussi, Adrian; Carvalho, Thiago Saads

    2015-01-01

    The effectiveness of fluoride in caries prevention has been convincingly proven. In recent years, researchers have investigated the preventive effects of different fluoride formulations on erosive tooth wear with positive results, but their action on caries and erosion prevention must be based on different requirements, because there is no sheltered area in the erosive process as there is in the subsurface carious lesions. Thus, any protective mechanism from fluoride concerning erosion is limited to the surface or the near surface layer of enamel. However, reports on other protective agents show superior preventive results. The mechanism of action of tin-containing products is related to tin deposition onto the tooth surface, as well as the incorporation of tin into the near-surface layer of enamel. These tin-rich deposits are less susceptible to dissolution and may result in enhanced protection of the underlying tooth. Titanium tetrafluoride forms a protective layer on the tooth surface. It is believed that this layer is made up of hydrated hydrogen titanium phosphate. Products containing phosphates and/or proteins may adsorb either to the pellicle, rendering it more protective against demineralization, or directly to the dental hard tissue, probably competing with H(+) at specific sites on the tooth surface. Other substances may further enhance precipitation of calcium phosphates on the enamel surface, protecting it from additional acid impacts. Hence, the future of fluoride alone in erosion prevention looks grim, but the combination of fluoride with protective agents, such as polyvalent metal ions and some polymers, has much brighter prospects. PMID:25871415

  18. The future of fluorides and other protective agents in erosion prevention.

    PubMed

    Lussi, Adrian; Carvalho, Thiago Saads

    2015-01-01

    The effectiveness of fluoride in caries prevention has been convincingly proven. In recent years, researchers have investigated the preventive effects of different fluoride formulations on erosive tooth wear with positive results, but their action on caries and erosion prevention must be based on different requirements, because there is no sheltered area in the erosive process as there is in the subsurface carious lesions. Thus, any protective mechanism from fluoride concerning erosion is limited to the surface or the near surface layer of enamel. However, reports on other protective agents show superior preventive results. The mechanism of action of tin-containing products is related to tin deposition onto the tooth surface, as well as the incorporation of tin into the near-surface layer of enamel. These tin-rich deposits are less susceptible to dissolution and may result in enhanced protection of the underlying tooth. Titanium tetrafluoride forms a protective layer on the tooth surface. It is believed that this layer is made up of hydrated hydrogen titanium phosphate. Products containing phosphates and/or proteins may adsorb either to the pellicle, rendering it more protective against demineralization, or directly to the dental hard tissue, probably competing with H(+) at specific sites on the tooth surface. Other substances may further enhance precipitation of calcium phosphates on the enamel surface, protecting it from additional acid impacts. Hence, the future of fluoride alone in erosion prevention looks grim, but the combination of fluoride with protective agents, such as polyvalent metal ions and some polymers, has much brighter prospects.

  19. The epidemic of obesity and changes in food intake: the Fluoride Hypothesis.

    PubMed

    Bray, George A

    2004-08-01

    The epidemic of obesity is worldwide. It will be followed by an epidemic of diabetes. Although there is a genetic basis for obesity and diabetes, the current epidemic reflects the failure of our ancient genes to cope with a modern toxic environment. To put it another way, the genetic background loads the gun, but the environment pulls the trigger. Diet, lifestyle and exercise are the cornerstones of current approaches to treating obesity. However, these approaches that depend on individuals making lifestyle changes have been ineffective in preventing the epidemic. An alternative model views obesity as an epidemiological disease with food(s) and other environmental agents acting on the host to produce disease. The consumption patterns for many foods have changed over the past 30 years, but the increase in the consumption of high-fructose corn syrup (HFCS) for soft drinks is far and away the largest. Moreover, the rise in HFCS intake is an environmental insult that has occurred at exactly the same time as obesity began to increase in prevalence. Rising soft drink consumption is associated with a decrease in milk consumption and a decrease in calcium intake, which has an inverse relationship to body mass index (BMI). To combat the epidemic of obesity, we need new strategies that flow from the epidemiological model. The Fluoride Hypothesis for obesity proposes that we can make environmental changes that when made, will reduce the epidemic of obesity, in much the same way as fluoride reduced the incidence of dental disease. Fluoride-like strategies can work without the personal effort required by changes in lifestyle. In this context, fluoride is also an acronym for treatment and prevention of obesity: For Lowering Universal Obesity Rates are Implement ideas that Don't demand Effort (FLUORIDE).

  20. Voriconazole Enhances the Osteogenic Activity of Human Osteoblasts In Vitro through a Fluoride-Independent Mechanism

    PubMed Central

    Allen, Kahtonna C.; Sanchez, Carlos J.; Niece, Krista L.; Wenke, Joseph C.

    2015-01-01

    Periostitis, which is characterized by bony pain and diffuse periosteal ossification, has been increasingly reported with prolonged clinical use of voriconazole. While resolution of clinical symptoms following discontinuation of therapy suggests a causative role for voriconazole, the biological mechanisms contributing to voriconazole-induced periostitis are unknown. To elucidate potential mechanisms, we exposed human osteoblasts in vitro to voriconazole or fluconazole at 15 or 200 μg/ml (reflecting systemic or local administration, respectively), under nonosteogenic or osteogenic conditions, for 1, 3, or 7 days and evaluated the effects on cell proliferation (reflected by total cellular DNA) and osteogenic differentiation (reflected by alkaline phosphatase activity, calcium accumulation, and expression of genes involved in osteogenic differentiation). Release of free fluoride, vascular endothelial growth factor (VEGF), and platelet-derived growth factor (PDGF) was also measured in cell supernatants of osteoblasts exposed to triazoles, with an ion-selective electrode (for free fluoride) and enzyme-linked immunosorbent assays (ELISAs) (for VEGF and PDGF). Voriconazole but not fluconazole significantly enhanced the proliferation and differentiation of osteoblasts. In contrast to clinical observations, no increases in free fluoride levels were detected following exposure to either voriconazole or fluconazole; however, significant increases in the expression of VEGF and PDGF by osteoblasts were observed following exposure to voriconazole. Our results demonstrate that voriconazole can induce osteoblast proliferation and enhance osteogenic activity in vitro. Importantly, and in contrast to the previously proposed mechanism of fluoride-stimulated osteogenesis, our findings suggest that voriconazole-induced periostitis may also occur through fluoride-independent mechanisms that enhance the expression of cytokines that can augment osteoblastic activity. PMID:26324277

  1. Isothermal vapor-liquid equilibria for the systems 1-chloro-1,1-difluoroethane + hydrogen fluoride, 1,1-dichloro-1-fluoroethane + hydrogen fluoride, and chlorodifluoromethane + hydrogen fluoride

    SciTech Connect

    Kang, Y.W.; Lee, Y.Y.

    1997-03-01

    Isothermal vapor-liquid equilibria for the three binary systems (1-chloro-1,1-difluoroethane + hydrogen fluoride, 1,1-dichloro-1-fluoroethane + hydrogen fluoride, and chlorodifluoromethane + hydrogen fluoride) have been measured. The experimental data for the binary systems are correlated with the NRTL equation with the vapor-phase association model for the mixtures containing hydrogen fluoride, and the relevant parameters are presented. All of the systems form minimum boiling heterogeneous azeotropes.

  2. Well waters fluoride in Enugu, Nigeria.

    PubMed

    Ogbu, I Si; Okoro, O Io; Ugwuja, E I

    2012-04-01

    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. PMID:23022857

  3. Delivery Challenges for Fluoride, Chlorhexidine and Xylitol

    PubMed Central

    Featherstone, John DB

    2006-01-01

    The progression or reversal of dental caries is determined by the balance between pathological and protective factors. It is well established that a) fluoride inhibits demineralization and enhances remineralization, b) chlorhexidine reduces the cariogenic bacterial challenge, and c) xylitol is non-cariogenic and has antibacterial properties. The challenge that we face is how best to deliver these anti-caries entities at true therapeutic levels, over time, to favorably tip the caries balance. High caries risk people, including children with Early Childhood Caries (ECC), are a special challenge, since high cariogenic bacterial activity can override fluoride therapy. Current fluoride and chlorhexidine varnishes deliver all their activity within about 24 hours. Early studies with experimental slow release fluoride devices retained elevated levels of fluoride for months in a therapeutic range but have not been pursued. Preventive dentistry has largely ignored the benefits of reducing the bacterial challenge, partially due to primitive and inadequate delivery systems. For example, Chlorhexidine applied as a rinse partially reduces some bacteria but not others that are hiding within the biofilm. Better antibacterials and better delivery systems are needed. Xylitol delivered by gum or lozenge appears to be effective clinically in reducing cariogenic bacteria and caries levels, but novel systems that deliver therapeutic amounts when needed would be a major advance, especially for young children. Reducing the cariogenic bacterial challenge and enhancing the effect of fluoride by the use of new sustained-delivery systems would have a major effect on dealing with caries as a disease. PMID:16934125

  4. Pump absorption and temperature distribution in erbium-doped double-clad fluoride-glass fibers.

    PubMed

    Gorjan, Martin; Marincek, Marko; Copic, Martin

    2009-10-26

    We investigate diode pump absorption and temperature distribution in three erbium-doped double-clad fluoride fibers. Absorption is measured via fluorescence intensity and temperature distribution is measured with thermal imaging. Ray-tracing calculations of absorption and heat-equation modeling of temperature distribution are also conducted. We found excellent agreement between measurements and calculations for all fibers. Results indicate that erbium-doped fluoride fiber lasers have already reached maximum output powers allowed under natural convection cooling, with fiber end being the most critical. We propose cooling and fiber design optimizations that may allow an order-of-magnitude further power-scaling.

  5. The effect of two remineralizing agents and natural saliva on bleached enamel hardness

    PubMed Central

    Heshmat, Haleh; Ganjkar, Maryam Hoorizad; Miri, Yasaman; Fard, Mohamad Javad Kharrazi

    2016-01-01

    Background: In order to compensate the adverse consequences of bleaching agents, the use of fluoride-containing remineralizing agents has been suggested by many researchers. The aim of this study was to compare the effect of applying two remineralizing materials on bleached enamel hardness and in comparison to natural saliva. Materials and Methods: In this experimental study, 30 enamel samples of sound human permanent molars were prepared for this study. Microhardness (MH) of all specimens was measured and 35% hydrogen peroxide was applied 3 times to the specimens. After completion of the bleaching process, MH of samples was measured and then enamel specimens were divided into three groups each of 10, specimens of groups 1 and 2 were subjected to daily application of hydroxyl apatite (Remin Pro) and casein phosphopeptide amorphous calcium phosphate fluoride (CPP-ACPF) (MI Paste Plus) pastes, respectively, for 15 days. In group 3, the specimens were stored in the operators' natural saliva at room temperature in this period of time. Final MH of all groups was measured. The data were analyzed using repeated measures ANOVA (α = 0.05). Results: The hardness significantly decreased in all groups following bleaching. Application of either Remin Pro, CPP-ACPF or natural saliva increased the hardness significantly. The hardness of the three test groups after 15 days were statistically similar to each other. Conclusion: The hardness of enamel increases eventually after exposure to either MI Paste Plus, Remin Pro or natural saliva. PMID:26962316

  6. Multi-criteria assessment of community-based fluoride-removal technologies for rural Ethiopia.

    PubMed

    Osterwalder, Lars; Johnson, C Annette; Yang, Hong; Johnston, Richard B

    2014-08-01

    Elevated concentrations of naturally-occurring fluoride in groundwater pose a serious health risk to millions of people living in the Ethiopian Rift Valley. In the absence of low-fluoride water resources of sufficient capacity, fluoride removal from drinking water is the accepted mitigation option. To date, five different community-level fluoride-removal technologies have been implemented in Ethiopia, although only a few units have been found in a functional state in the field. Which technology should be promoted and up-scaled is the subject of controversial debate amongst key stakeholders. This paper describes a multi-criteria decision analysis exercise, which was conducted with the participation of stakeholders in Ethiopia during a one-day workshop, to assess in an objective and transparent manner the available technology options. Criteria for technology comparison were selected and weighted, thus enabling the participants to assess the advantages and disadvantages of the different technologies and hear the views of other stakeholders. It was shown that there is no single most-preferable, technical solution for fluoride removal in Ethiopia. Selection of the most suitable solution depends on location-specific parameters and on the relative importance given to different criteria by the stakeholders involved. The data presented in this paper can be used as reference values for Ethiopia.

  7. Substituent effects on fluoride binding by lanthanide complexes of DOTA-tetraamides.

    PubMed

    Blackburn, Octavia A; Routledge, Jack D; Jennings, Laura B; Rees, Nicholas H; Kenwright, Alan M; Beer, Paul D; Faulkner, Stephen

    2016-02-21

    Fluoride binding by a series of europium and ytterbium complexes of DOTA-tetraamide ligands derived from primary, secondary and tertiary amides has been studied by NMR and luminescence spectroscopies. In all the systems studied, fluoride binding results in a change in the nature of the magnetic anisotropy at the metal centre from an easy axis, to an easy plane anisotropy. This results in reversal of the peaks in the NMR spectra, and in changes to the fine structure of the luminescence spectra. Furthermore, changes to the periphery of the binding cavity are implicated in determining the affinity constant for fluoride. There are clear differences in the entropic contribution to the free energy of activation between systems with benzylic amides and those with methylamides. PMID:26765788

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

    PubMed

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

    2000-03-01

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

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

    PubMed

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

    2013-01-01

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

  10. Hydrogen fluoride and deuterium fluoride lasers. Citations from the International Aerospace Abstracts data base

    NASA Technical Reports Server (NTRS)

    Mauk, S. C.

    1980-01-01

    Research cited from the international literature adresses various aspects of hydrogen fluoride and deuterium fluoride lasers. Topics covered include flows, laser outputs, molecular relaxation, molecular rotation, energy conversion efficiency, reaction kinetics, and laser materials. Continous wave and pulsed laser are considered. This updated bibliography contains 283 citations, 53 of which are new additions to the previous edition.

  11. CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING IN CENTER, ...

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

    CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING IN CENTER, CALCIUM CHLORIDE STORAGE BUILDING ON RIGHT WITH SA (SODA ASH) BUILDING IN RIGHT BACKGROUND. - Solvay Process Company, Calcium Chloride Plant, Between Willis & Milton Avenues, Solvay, Onondaga County, NY

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

    PubMed

    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.

  13. Hydrothermal treatment of naturally contaminated maize in the presence of sodium metabisulfite, methylamine and calcium hydroxide; effects on the concentration of zearalenone and deoxynivalenol.

    PubMed

    Rempe, Inga; Kersten, Susanne; Valenta, Hana; Dänicke, Sven

    2013-08-01

    Fusarium toxin-contaminated ground maize was hydrothermally treated in the presence of different combinations of chemicals in order to simultaneously reduce zearalenone (ZEA) and deoxynivalenol (DON) concentrations. Treatments were carried out in a laboratory conditioner at 80 °C and 17 % moisture. Six different treatments were performed, consisting of 3 doses of methylamine (MMA; 2.5, 5 and 10 g/kg maize) at a constant dose of 5 g sodium metabisulfite (SBS)/kg, either with or without the addition of 20 g calcium hydroxide (Ca(OH)2)/kg. The used maize was contaminated with approximately 45.99 mg DON/kg and 3.46 mg ZEA/kg. Without the addition of Ca(OH)2, DON reductions reached approximately 82% after 1-min treatment and the toxin disappeared nearly completely after 10 min when 2.5 or 5 g MMA were applied. ZEA concentrations were only marginally affected. In the presence of Ca(OH)2, reductions in DON concentrations were lower, but were enhanced by increasing doses of MMA. ZEA concentrations were reduced by 72, 85 and 95% within the first 5 min of the treatment at MMA dosages of 2.5, 5 and 10 g/kg maize, respectively. The application of SBS in combination with a strong alkaline during hydrothermal treatment seems to be a promising approach to simultaneously decontaminate even high amounts of DON and ZEA in ground maize and may contribute to reduce the toxin load of diets.

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

    PubMed Central

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

    2016-01-01

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

  15. Calcium quarks.

    PubMed

    Niggli, Ernst; Egger, Marcel

    2002-05-01

    Elementary subcellular Ca2+ signals arising from the opening of single ion channels may offer the possibility to examine the stochastic behavior and the microscopic chemical reaction rates of these channel proteins in their natural environment. Such an analysis can yield detailed information about the molecular function that cannot be derived from recordings obtained from an ensemble of channels. In this review, we summarize experimental evidence suggesting that Ca2+ sparks, elementary Ca2+ signaling events of cardiac and skeletal muscle excitation contraction coupling, may be comprised of a number of smaller Ca2+ signaling events, the Ca2+ quarks.

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

    USGS Publications Warehouse

    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.

  17. Effects of Systemic Fluoride and in vitro Fluoride Treatment on Enamel Crystals

    PubMed Central

    Chen, H.; Czajka-Jakubowska, A.; Spencer, N.J.; Mansfield, J.F.; Robinson, C.; Clarkson, B.H.

    2008-01-01

    Systemically administered fluoride at a concentration of 75 ppm increases the surface roughness of developing enamel crystals in rats, which may be significant in advancing our understanding of the biological mechanism of fluorosis. Thus, the aim of this study was to investigate whether the increased surface roughness may be a result of surface restructuring by the direct action of fluoride at the crystal surface. We examined the fluoride dose-dependent roughening of enamel crystal surfaces in vivo, in the rat, and whether this roughening could be mimicked by the in vitro treatment of rat enamel crystals with neutral pH fluoride solutions. Our results showed that enamel crystal surface roughness increased after treatment with increasing fluoride ion concentrations, whether applied in vitro or administered systemically. This suggests a mechanism, alongside others, for the increased surface roughness of crystals in fluorotic enamel. PMID:17062747

  18. Mechanism of Electrophilic Fluorination with Pd(IV): Fluoride Capture and Subsequent Oxidative Fluoride Transfer†, ‡

    PubMed Central

    Brandt, Jochen R.; Lee, Eunsung; Boursalian, Gregory B.

    2013-01-01

    Electrophilic fluorinating reagents derived from fluoride are desirable for the synthesis of 18F-labeled molecules for positron emission tomography (PET). Here, we study the mechanism by which a Pd(IV)-complex captures fluoride and subsequently transfers it to nucleophiles. The intermediate Pd(IV)-F is formed with high rates even at the nano- to micromolar fluoride concentrations typical for radiosyntheses with 18F due to fast formation of an outer-sphere complex between fluoride and Pd(IV). The subsequent fluorine transfer from the Pd(IV)-F complex is proposed to proceed through an unusual SET/fluoride transfer/SET mechanism. The findings detailed in this manuscript provide a theoretical foundation suitable for addressing a more general approach for electrophilic fluorination with high specific activity 18F PET imaging. PMID:24376910

  19. Calcium and Vitamin D

    MedlinePlus

    ... to your weekly shopping list. Produce Serving Size Estimated Calcium* Collard greens, frozen 8 oz 360 mg ... Oranges 1 whole 55 mg Seafood Serving Size Estimated Calcium* Sardines, canned with bones 3 oz 325 ...

  20. Fenoprofen calcium overdose

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/002649.htm Fenoprofen calcium overdose To use the sharing features on this page, please enable JavaScript. Fenoprofen calcium is a type of medicine called a nonsteroidal ...

  1. Calcium and bones

    MedlinePlus

    ... only gets the calcium it needs through the food you eat, or from supplements. If you do ... materials it needs to build bones. High-calcium foods include: Milk Cheese Ice cream Leafy green vegetables, ...

  2. Calcium in Plants

    PubMed Central

    WHITE, PHILIP J.; BROADLEY, MARTIN R.

    2003-01-01

    Calcium is an essential plant nutrient. It is required for various structural roles in the cell wall and membranes, it is a counter‐cation for inorganic and organic anions in the vacuole, and the cytosolic Ca2+ concentration ([Ca2+]cyt) is an obligate intracellular messenger coordinating responses to numerous developmental cues and environmental challenges. This article provides an overview of the nutritional requirements of different plants for Ca, and how this impacts on natural flora and the Ca content of crops. It also reviews recent work on (a) the mechanisms of Ca2+ transport across cellular membranes, (b) understanding the origins and specificity of [Ca2+]cyt signals and (c) characterizing the cellular [Ca2+]cyt‐sensors (such as calmodulin, calcineurin B‐like proteins and calcium‐dependent protein kinases) that allow plant cells to respond appropriately to [Ca2+]cyt signals. PMID:12933363

  3. Calcium and Mitosis

    NASA Technical Reports Server (NTRS)

    Hepler, P.

    1983-01-01

    Although the mechanism of calcium regulation is not understood, there is evidence that calcium plays a role in mitosis. Experiments conducted show that: (1) the spindle apparatus contains a highly developed membrane system that has many characteristics of sarcoplasmic reticulum of muscle; (2) this membrane system contains calcium; and (3) there are ionic fluxes occurring during mitosis which can be seen by a variety of fluorescence probes. Whether the process of mitosis can be modulated by experimentally modulating calcium is discussed.

  4. Human Health Impact of Fluoride in Groundwater in the Chiang Mai Basin

    NASA Astrophysics Data System (ADS)

    Matsui, Y.; Takizawa, S.; Wattanachira, S.; Wongrueng, A.; Ibaraki, M.

    2005-12-01

    . Groundwater of the other area contains a high fluoride concentration and is Na-bicarbonate dominant. We will present how naturally-occurring fluoride found in this groundwater has impacted the health of a large portion of residents in the Chiang Mai Basin, and we will explain the mechanism that differentiates Ca concentration, which controls fluoride concentration in groundwater, between different areas in the Basin.

  5. Performance of an optimized Zr-based nanoparticle-embedded PSF blend hollow fiber membrane in treatment of fluoride contaminated water.

    PubMed

    He, Jinsong; Siah, Tiong-Shie; Paul Chen, J

    2014-06-01

    Consumption of water that has excessive fluoride can cause adverse health impacts on human beings. A Zr-based nanoparticle-embedded PSF blend hollow fiber membrane was successfully prepared and optimized for removal of fluoride from the aqueous solution. Both static and dynamic adsorption of fluoride on the membrane was investigated. It was showed that the membrane could effectively remove fluoride within a wide pH ranging from 3 to 10. At neutral pH, the adsorption equilibrium was reached within 24 h. The maximum adsorption capacity of the optimized membrane was 60.65 mg/g, much higher than many commercial adsorbents. The presence of NO3(-), SiO3(2-) or HA has insignificant effects on the fluoride removal. However, the removal was retarded as the concentration of HCO3(-) or PO4(3-) was increased. Furthermore, the membrane could remove fluoride efficiently through the continuous filtration, even in presence of natural organic matters. The spent membrane could be regenerated and then reused for the removal of fluoride with great efficiency. The adsorption history could be well described by an intraparticle diffusion model. The XPS analysis showed that the adsorption of fluoride was mainly associated with the ion-exchange between SO4(2-) and F(-) ions. Finally, the toxicity analysis revealed that the treated water was safe for human consumption. PMID:24657326

  6. Biotic Nitrogen Enrichment Regulates Calcium Sources to Forests

    NASA Astrophysics Data System (ADS)

    Pett-Ridge, J. C.; Perakis, S. S.; Hynicka, J. D.

    2015-12-01

    Calcium is an essential nutrient in forest ecosystems that is susceptible to leaching loss and depletion. Calcium depletion can affect plant and animal productivity, soil acid buffering capacity, and fluxes of carbon and water. Excess nitrogen supply and associated soil acidification are often implicated in short-term calcium loss from soils, but the long-term role of nitrogen enrichment on calcium sources and resupply is unknown. Here we use strontium isotopes (87Sr/86Sr) as a proxy for calcium to investigate how soil nitrogen enrichment from biological nitrogen fixation interacts with bedrock calcium to regulate both short-term available supplies and the long-term sources of calcium in montane conifer forests. Our study examines 22 sites in western Oregon, spanning a 20-fold range of bedrock calcium on sedimentary and basaltic lithologies. In contrast to previous studies emphasizing abiotic control of weathering as a determinant of long-term ecosystem calcium dynamics and sources (via bedrock fertility, climate, or topographic/tectonic controls) we find instead that that biotic nitrogen enrichment of soil can strongly regulate calcium sources and supplies in forest ecosystems. For forests on calcium-rich basaltic bedrock, increasing nitrogen enrichment causes calcium sources to shift from rock-weathering to atmospheric dominance, with minimal influence from other major soil forming factors, despite regionally high rates of tectonic uplift and erosion that can rejuvenate weathering supply of soil minerals. For forests on calcium-poor sedimentary bedrock, we find that atmospheric inputs dominate regardless of degree of nitrogen enrichment. Short-term measures of soil and ecosystem calcium fertility are decoupled from calcium source sustainability, with fundamental implications for understanding nitrogen impacts, both in natural ecosystems and in the context of global change. Our finding that long-term nitrogen enrichment increases forest reliance on atmospheric

  7. Analysis of the erosive potential of calcium-containing acidic beverages.

    PubMed

    Hara, Anderson T; Zero, Domenick T

    2008-02-01

    The occurrence and progress of enamel demineralization may be reduced in the presence of its reaction products, such as calcium. Therefore, in this study the hypothesis that lower erosive potential may be expected for calcium-containing beverages was tested. Ten commercially available beverages, five with and five without calcium supplementation, were tested in two phases. In the first phase, the pH, titratable acidity, and concentrations of calcium (total and ionic), phosphorus and fluoride, were analyzed. In the second phase, the ability of the test products to erode enamel was measured, at different time-points. Within the chemical properties tested, pH, calcium-ion concentration, and total calcium showed a strong correlation with enamel demineralization and enamel wear. Lower levels of enamel demineralization and wear were found for most of the calcium-containing beverages than for those without calcium. Calcium-ion content, as well as pH, were found to be good predictors of the erosive potential of the beverages tested. Generally, beverages supplemented with calcium had a reduced capacity to demineralize enamel.

  8. The Northland fluoridation advocacy programme: an evaluation.

    PubMed

    Gowda, Sunitha; Thomas, David R

    2008-12-01

    On 20 July 2006, the Far North District Council resolved to fluoridate Kaitaia and Kaikohe. This was the first such initiative by any Territorial Local Authority (TLA) in New Zealand for 23 years, and resulted from a fluoridation advocacy programme. This paper describes the programme implementation, assesses its consistency with the principles of the Treaty of Waitangi, and critically examines the collaboration between the fluoride advocate and the key stakeholders. Process evaluation identified three main categories of programme implementation: policy advocacy, community action projects, and media advocacy. The collaboration of iwi, Maori health providers and the community suggests that the programme was consistent with the principles (partnership, participation and protection) ofthe Treaty ofWaitangi. Media advocacy played an important role in reflecting and engaging community views on fluoridation, and it influenced decision-making by the Far North District Council. The simultaneous, combined 'top-down and bottom-up' approach was an effective and successful strategy for fluoridation advocacy in the community. Less integrated approaches implemented on their own (such as the 'top down' approach in Whangarei and the 'bottom-up' approach in Dargaville) were not effective. PMID:19180864

  9. Emissions of fluorides from welding processes.

    PubMed

    Szewczyńska, Małgorzata; Pągowska, Emilia; Pyrzyńska, Krystyna

    2015-11-01

    The levels of fluoride airborne particulates emitted from welding processes were investigated. They were sampled with the patented IOM Sampler, developed by J. H. Vincent and D. Mark at the Institute of Occupational Medicine (IOM), personal inhalable sampler for simultaneous collection of the inhalable and respirable size fractions. Ion chromatography with conductometric detection was used for quantitative analysis. The efficiency of fluoride extraction from the cellulose filter of the IOM sampler was examined using the standard sample of urban air particle matter SRM-1648a. The best results for extraction were obtained when water and the anionic surfactant N-Cetyl-N-N-N-trimethylammonium bromide (CTAB) were used in an ultrasonic bath. The limits of detection and quantification for the whole procedure were 8μg/L and 24μg/L, respectively. The linear range of calibration was 0.01-10mg/L, which corresponds to 0.0001-0.1mg of fluorides per m(3) in collection of a 20L air sample. The concentration of fluorides in the respirable fraction of collected air samples was in the range of 0.20-1.82mg/m(3), while the inhalable fraction contained 0.23-1.96mg/m(3) of fluorides during an eight-hour working day in the welding room. PMID:26574102

  10. Emissions of fluorides from welding processes.

    PubMed

    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.

  11. Removing Fluoride Ions with Continously Fed Activated Alumina.

    ERIC Educational Resources Information Center

    Wu, Yeun C.; Itemaking, Isara Cholapranee

    1979-01-01

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

  12. Effects of biochar on air and water permeability and colloid and phosphorus leaching in soils from a natural calcium carbonate gradient.

    PubMed

    Kumari, K G I D; Moldrup, Per; Paradelo, Marcos; Elsgaard, Lars; Hauggaard-Nielsen, Henrik; de Jonge, Lis W

    2014-03-01

    Application of biochar to agricultural fields to improve soil quality has increased in popularity in recent years, but limited attention is generally paid to existing field conditions before biochar application. This study examined the short-term physicochemical effects of biochar amendment in an agricultural field in Denmark with a calcium carbonate (CaCO) gradient. The field comprised four reference plots and four plots to which biochar (birch wood pyrolyzed at 500°C) was applied at a rate of 20 t ha. Five undisturbed soil columns (10 cm diam., 8 cm height) were sampled from each plot 7 mo after biochar application, and a series of leaching experiments was conducted. The leachate was analyzed for tritium (used as a tracer), colloids, and phosphorus concentration. The results revealed that the presence of CaCO has resulted in marked changes in soil structure (bulk density) and soil chemical properties (e.g., pH and ionic strength), which significantly affected air and water transport and colloid and phosphorous leaching. In denser soils (bulk density, 1.57-1.69 g cm) preferential flow dominated the transport and caused an enhanced movement of air and water, whereas in less dense soils (bulk density, 1.38-1.52 g cm) matrix flow predominated the transport. Compared with reference soils, biochar-amended soils showed slightly lower air permeability and a shorter travel time for 5% of the applied tracer (tritium) to leach through the soil columns. Colloid and phosphorus leaching was observed to be time dependent in soils with low CaCO. Biochar-amended soils showed higher colloid and P release than reference soils. Field-scale variations in total colloid and P leaching reflected clear effects of changes in pH and ionic strength due to the presence of CaCO. There was a linear relationship between colloid and P concentrations in the leachate, suggesting that colloid-facilitated P leaching was the dominant P transport mechanism. PMID:25602666

  13. Dietary calcium, phosphorus, and phytase effects on bird performance, intestinal morphology, mineral digestibility, and bone ash during a natural necrotic enteritis episode.

    PubMed

    Paiva, Diego; Walk, Carrie; McElroy, Audrey

    2014-11-01

    The objective of this study was to evaluate the effects of dietary Ca, P, and phytase on performance, intestinal morphology, bone ash, and Ca and P digestibility during a necrotic enteritis (NE) outbreak. The 35-d trial was designed as a 2 × 2 × 2 factorial, which included 2 Ca levels (0.6 and 0.9%), 2 P levels (0.3 and 0.45%), and 2 levels of phytase [0 and 1,000 phytase units (FTU)/kg]. Birds were placed on litter from a previous flock that exhibited clinical signs of NE. Birds and feed were weighed on d 12, 19, and 35, and BW gain, feed intake, and feed conversion were calculated. Mortality was recorded daily, and gastrointestinal pH was measured. Tibias and ileal digesta were also collected. Birds began exhibiting clinical signs of NE on d 9, and NE-associated mortality persisted until d 26. Dietary Ca supplemented at 0.9% or inclusion of 1,000 FTU/kg of phytase significantly increased mortality compared with 0.6% Ca or 0 FTU/kg of phytase, respectively. From d 0 to 12, birds fed 0.9% Ca and 0.45% available P with phytase had greater BW gain compared with birds fed 0.6% Ca, 0.45% available P, and phytase. From d 0 to 19, birds fed diets with 0.9% Ca and 0.3% available P had decreased feed intake and improved feed conversion compared with birds fed 0.9% Ca and 0.45% available P. Calcium at 0.9% increased gizzard (d 19) and jejunum (d 12) pH. Phytase supplementation significantly increased Ca digestibility regardless of Ca and P levels of the diets. In addition, diets containing 0.6% Ca and 1,000 FTU/kg of phytase resulted in a significant increase in P digestibility. The results suggest that dietary Ca level may influence NE-associated mortality. In addition, bird performance was affected by interactions of Ca, P, and phytase during the exposure to Clostridium perfringens and the subsequent NE outbreak. Results showed improvements in bird performance when birds were fed 0.6% Ca and 0.3% P in diets supplemented with phytase, which was likely consequent to the

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

    NASA Astrophysics Data System (ADS)

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

    A study was carried out to determine fluoride concentration in groundwaters of Nathenje area situated in Lilongwe District in the central region of Malawi. Water samples were collected from 176 boreholes and shallow wells during different months in 2001 and 2002. Samples were then analysed for fluoride by using a fluoride electrode and an ion selective meter. The results showed that fluoride concentrations for the rainy season varied from <0.5 to 6.98 ± 0.01 mg/l with 52.9% of the boreholes above the World Health Organisation (WHO) maximum permissible limit of 1.5 mg/l. Fluoride concentrations for dry season ranged from <0.5 to 7.02 ± 0.02 mg/l with 50.8% of boreholes above 1.5 mg/l. Fluoride concentrations for the two seasons were significantly different from each other ( p < 0.05). Fluoride data was used to produce a fluoride distribution map. From the map, it was observed that fluoride concentrations in this area followed a pattern. The central part of Nathenje had high fluoride concentration of between 2 and 7.02 mg/l and these high fluoride values seemed to extend eastwards beyond the boundary of the study area. However, the southern and western parts had <1 mg/l of fluoride. The high groundwater fluoride values seem to be associated with the weathered basement complex containing biotite that is a probable source of fluoride. The other suspected sources of fluoride in Nathenje groundwater could be due to the dissolution of hornblende, fluorite and amphibole, which are reported to occur in rocks and soils in this area. There was evidence of dental fluorosis in areas where the fluoride concentration was high.

  15. METHOD FOR DISSOLVING LANTHANUM FLUORIDE CARRIER FOR PLUTONIUM

    DOEpatents

    Koshland, D.E. Jr.; Willard, J.E.

    1961-08-01

    A method is described for dissolving lanthanum fluoride precipitates which is applicable to lanthanum fluoride carrier precipitation processes for recovery of plutonium values from aqueous solutions. The lanthanum fluoride precipitate is contacted with an aqueous acidic solution containing dissolved zirconium in the tetravalent oxidation state. The presence of the zirconium increases the lanthanum fluoride dissolved and makes any tetravalent plutonium present more readily oxidizable to the hexavalent state. (AEC)

  16. Promotion of beta-glucan synthase activity in corn microsomal membranes by calcium and protein phosphorylation

    NASA Technical Reports Server (NTRS)

    Paliyath, G.; Poovaiah, B. W.

    1988-01-01

    Regulation of the activity of beta-glucan synthase was studied using microsomal preparations from corn coleoptiles. The specific activity as measured by the incorporation of glucose from uridine diphospho-D-[U-14C]glucose varied between 5 to 15 pmol (mg protein)-1 min-1. Calcium promoted beta-glucan synthase activity and the promotion was observed at free calcium concentrations as low as 1 micromole. Kinetic analysis of substrate-velocity curve showed an apparent Km of 1.92 x 10(-4) M for UDPG. Calcium increased the Vmax from 5.88 x 10(-7) mol liter-1 min-1 in the absence of calcium to 9.52 x 10(-7) mol liter-1 min-1 and 1.66 x 10(-6) mol liter-1 min-1 in the presence of 0.5 mM and 1 mM calcium, respectively. The Km values remained the same under these conditions. Addition of ATP further increased the activity above the calcium-promoted level. Sodium fluoride, a phosphoprotein phosphatase inhibitor, promoted glucan synthase activity indicating that phosphorylation and dephosphorylation are involved in the regulation of the enzyme activity. Increasing the concentration of sodium fluoride from 0.25 mM to 10 mM increased glucan synthase activity five-fold over the + calcium + ATP control. Phosphorylation of membrane proteins also showed a similar increase under these conditions. Calmodulin, in the presence of calcium and ATP stimulated glucan synthase activity substantially, indicating that calmodulin could be involved in the calcium-dependent phosphorylation and promotion of beta-glucan synthase activity. The role of calcium in mediating auxin action is discussed.

  17. Barium solubility in colquiriite fluorides

    SciTech Connect

    Yaobo Yin; Keszler, D.A. )

    1993-12-01

    Several crystals in the family of Colquiriite fluorides LiAEMF[sub 6] (AE = Ca, Sr; M = Al, Ga, Cr) have been reported to function as efficient, broadly tunable laser materials when doped with the ion Cr[sup 3+]. The optical characteristics of the Cr[sup 3+] ion are considerably affected by the specific AE atom in the crystal. In this paper the systems LiSr[sub 1[minus]x]Ba[sub x]MF[sub 6](M = Al, Ga) have been studied by powder and single-crystal X-ray diffraction methods. Solubility limits of x = 0.06 for the Al compound and x = 0.20 for the Ga compound have been established. The structures of LiSr[sub 0.94(1)]Ba[sub 0.06]AlF[sub 6] and LiSr[sub 0.80(1)]Ba[sub 0.20]GaF[sub 6] corresponding to these limits are isotypic to the mineral Colquiriite. Each crystallizes in space group P[bar 3]1c: LiSr[sub 0.94]Ba[sub 0.06]AlF[sub 6]: a = 5.096(1) [angstrom], c = 10.269(2) [angstrom], R = 0.034, R[sub w] = 0.041; and LiSr[sub 0.80]Ba[sub 0.20]GaF[sub 6]: a = 5.173(1) [angstrom], c = 10.415(1) [angstrom], R = 0.028, R[sub w] = 0.033. The trigonal F planes about the Al and Ga atoms are rotated, one relative to the other, by 68.0 and 69.0[degrees], respectively.

  18. Mitochondria: the calcium connection.

    PubMed

    Contreras, Laura; Drago, Ilaria; Zampese, Enrico; Pozzan, Tullio

    2010-01-01

    Calcium handling by mitochondria is a key feature in cell life. It is involved in energy production for cell activity, in buffering and shaping cytosolic calcium rises and also in determining cell fate by triggering or preventing apoptosis. Both mitochondria and the mechanisms involved in the control of calcium homeostasis have been extensively studied, but they still provide researchers with long-standing or even new challenges. Technical improvements in the tools employed for the investigation of calcium dynamics have been-and are still-opening new perspectives in this field, and more prominently for mitochondria. In this review we present a state-of-the-art toolkit for calcium measurements, with major emphasis on the advantages of genetically encoded indicators. These indicators can be efficiently and selectively targeted to specific cellular sub-compartments, allowing previously unavailable high-definition calcium dynamic studies. We also summarize the main features of cellular and, in more detail, mitochondrial calcium handling, especially focusing on the latest breakthroughs in the field, such as the recent direct characterization of the calcium microdomains that occur on the mitochondrial surface upon cellular stimulation. Additionally, we provide a major example of the key role played by calcium in patho-physiology by briefly describing the extensively reported-albeit highly controversial-alterations of calcium homeostasis in Alzheimer's disease, casting lights on the possible alterations in mitochondrial calcium handling in this pathology.

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

    PubMed

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

    2014-09-01

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

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

    PubMed Central

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

    2014-01-01

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