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Sample records for mixed metal fluorides

  1. Synthesis of nanocrystalline mixed metal fluorides in nonaqueous medium

    Indian Academy of Sciences (India)

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

    2009-12-01

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

  2. Hydrothermal synthesis of mixed rare earth-alkali metal or ammonium fluorides

    Institute of Scientific and Technical Information of China (English)

    由芳田; 黄世华; 时秋峰

    2010-01-01

    The recent results on hydrothermal synthesis of mixed rare earth-alkali or ammonium fluorides were presented. The initial ratios of the starting materials, pH value and reaction temperature were the critical factors for obtaining the single-phase product. Four main types of complex rare earth fluorides, AREF4, A2REF5, ARE2F7 and ARE3F10 (A=Na+, K+, Rb+, NH4+), appeared in the primary hydrothermal reactions. The correlation between cation sizes and the formation of mixed rare earth fluorides under mild hydro...

  3. Mixed-Metal Carbonate Fluorides as Deep-Ultraviolet Nonlinear Optical Materials.

    Science.gov (United States)

    Tran, T Thao; Young, Joshua; Rondinelli, James M; Halasyamani, P Shiv

    2017-01-25

    Noncentrosymmetric mixed-metal carbonate fluorides are promising materials for deep-ultraviolet (DUV) nonlinear optical (NLO) applications. We report on the synthesis, characterization, structure-property relationships, and electronic structure calculations on two new DUV NLO materials: KMgCO3F and Cs9Mg6(CO3)8F5. Both materials are noncentrosymmetric (NCS). KMgCO3F crystallizes in the achiral and nonpolar NCS space group P6̅2m, whereas Cs9Mg6(CO3)8F5 is found in the polar space group Pmn21. The compounds have three-dimensional structures built up from corner-shared magnesium oxyfluoride and magnesium oxide octahedra. KMgCO3F (Cs9Mg6(CO3)8F5) exhibits second-order harmonic generation (SHG) at both 1064 and 532 nm incident radiation with efficiencies of 120 (20) × α-SiO2 and 0.33 (0.10) × β-BaB2O4, respectively. In addition, short absorption edges of <200 and 208 nm for KMgCO3F and Cs9Mg6(CO3)8F5, respectively, are observed. We compute the electron localization function and density of states of these two compounds using first-principles density functional theory, and show that the different NLO responses arise from differences in the denticity and alignment of the anionic carbonate units. Finally, an examination of the known SHG active AMCO3F (A = alkali metal, M = alkaline earth metal, Zn, Cd, or Pb) materials indicates that, on average, smaller A cations and larger M cations result in increased SHG efficiencies.

  4. Heavy Metal Fluoride Glasses.

    Science.gov (United States)

    1987-04-01

    i 2N E ihhhhh1112h MEmhhhhEEEohhhhE I.’....momo 111111111’-20 LA ’Ll2. AFWL-TR-86-37 AFWL-TR- 86-37 oT C ,l C ’-’ N HEAVY METAL FLUORIDE GLASSES 0nI...Secwrit CkasmfcationJ HEAVY METAL FLUORIDE GLASSES 12. PERSONAL AUTHOR(S) Reisfield, Renata; and Eyal, Mrek 13. TYPE OF REPORT 113b. TIME COVERED 114...glasses containing about 50 mole% of ZrF4 [which can be replaced by HfF 4 or TIF 4 (Refs. 1-3) or heavy metal fluorides based on PbF2 and on 3d-group

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

    African Journals Online (AJOL)

    Preferred Customer

    For comparative analysis of fluoride and metals in soil and water, water samples were ..... one is from rapidly soluble fluoride complex like cryolite (Na3AlF6) found in water ..... Atlabachew, M.; Chandravanshi, B.S.; Zewge, F.; Redi, M. Toxicol.

  6. Thermodynamic data-base for metal fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Jae Hyung; Lee, Byung Gik; Kang, Young Ho and others

    2001-05-01

    This study is aimed at collecting useful data of thermodynamic properties of various metal fluorides. Many thermodynamic data for metal fluorides are needed for the effective development, but no report of data-base was published. Accordingly, the objective of this report is to rearrange systematically the existing thermodynamic data based on metal fluorides and is to use it as basic data for the development of pyrochemical process. The physicochemical properties of various metal fluorides and metals were collected from literature and such existing data base as HSC code, TAPP code, FACT code, JANAF table, NEA data-base, CRC handbook. As major contents of the thermodynamic data-base, the physicochemical properties such as formation energy, viscosity, density, vapor pressure, etc. were collected. Especially, some phase diagrams of eutectic molten fluorides are plotted and thermodynamic data of liquid metals are also compiled. In the future, the technical report is to be used as basic data for the development of the pyrochemical process which is being carried out as a long-term nuclear R and D project.

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

    Institute of Scientific and Technical Information of China (English)

    梁鹏; 张艺; 汪东风; 徐莹; 罗斓

    2013-01-01

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

  8. A Process for Making Bulk Heavy Metal Fluoride Glasses.

    Science.gov (United States)

    This invention relates to the preparation of glasses, and, in particular, relates to the preparation of heavy metal fluoride glasses with...reproducible high optical qualities. Considerable effort has been expended to develop heavy metal fluoride glasses ( HMFG ) as a viable family of infrared

  9. Metal Fluoride Complexes of Na,K-ATPase

    Science.gov (United States)

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

    2011-01-01

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

  10. [Mechanism study of fluoride adsorption by hydrous metal oxides].

    Science.gov (United States)

    Guo, Hui-Chao; Li, Wen-Jun; Chang, Zhi-Dong; Wang, Huan-Ying; Zhou, Yue

    2011-08-01

    Hydrous oxides of cerium, aluminum, nickel and copper were prepared by alkaline precipitation method. Langmuir adsorption isotherm was studied and specific surface area was measured by BET method through N2 adsorption-desorption process. IR characterization of hydrous metal oxides before and after fluoride adsorption was also studied. Results show that different hydrous metal oxides have different specific surface areas and their pore size distributions also are not all the same. Adsorption capacity is not directly dependent on the specific surface area. Isotherm study indicates that the adsorption follows Langmuir model and shows the feature of monolayer adsorption. IR study before and after fluoride adsorption shows that different hydrous metal oxides have similar adsorption sites in the same IR region as well as adsorption sites in the different IR region. The comprehensive interaction of these adsorption sites with fluoride ions results in the different adsorption capacity of different hydrous metal oxides.

  11. Crystallization of heavy metal fluoride glasses

    Science.gov (United States)

    Bansal, Narottam P.; Bruce, Allan J.; Doremus, R. H.; Moynihan, C. T.

    1984-01-01

    The kinetics of crystallization of a number of fluorozirconate glasses were studied using isothermal and dynamic differential scanning calorimetry and X-ray diffraction. The addition of the fluorides LiF, NaF, AlF3, LaF3 to a base glass composition of ZrF4-BaF2 reduced the tendency to crystallize, probably by modifying the viscosity-temperature relation. ZrF4-BaF2-LaF3-AlF3-NaF glass was the most stable against devitrification and perhaps is the best composition for optical fibers with low scattering loss. Some glasses first crystallize out into metastable beta-BaZr2F10 and beta-BaZrF6 phases, which transform into the most stable alpha-phases when heated to higher temperatures. The size of the crystallites was estimated to be about 600 A from X-ray diffraction.

  12. Plasma assisted deposition of metal fluorides for 193nm applications

    Science.gov (United States)

    Bischoff, Martin; Sode, Maik; Gaebler, Dieter; Kaiser, Norbert; Tuennermann, Andreas

    2008-10-01

    The ArF lithography technology requires a minimization of optical losses due to scattering and absorption. Consequently it is necessary to optimize the coating process of metal fluorides. The properties of metal fluoride thin films are mainly affected by the deposition methods, their parameters, and the vacuum conditions. Until now the best results were achieved by metal boat evaporation with high substrate temperature and without plasma assistance. In fact, it was demonstrated that the plasma assisted deposition process results in optical thin films with high packing density but the losses due to absorption were extremely high for deep and vacuum ultraviolet applications. This paper will demonstrate that most of the common metal fluorides can be deposited by electron beam evaporation with plasma assistance. In comparison to other deposition methods, the prepared thin films show low absorption in the VUV spectral range, high packing density, and less water content. The densification of the thin films was performed by a Leybold LION plasma source. As working gas, a variable mixture of fluorine and argon gas was chosen. To understand the deposition process and the interaction of the plasma with the deposition material, various characterization methods like plasma emission spectroscopy and ion current measurements were implemented.

  13. Fluoride

    Science.gov (United States)

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

  14. Effects of Gravity on Processing Heavy Metal Fluoride Fibers

    Science.gov (United States)

    Tucker, Dennis S.; Workman, Gary L.; Smith, Guy A.

    1997-01-01

    The effects of gravity on the crystal nucleation of heavy metal fluoride fibers have been studied in preliminary experiments utilizing NASA's KC-135 reduced gravity aircraft and a microgravity sounding rocket flight. Commercially produced fibers were heated to the crystallization temperature in normal and reduced gravity. The fibers processed in normal gravity showed complete crystallization while the fibers processed in reduced gravity did not show signs of crystallization.

  15. Metal Fluoride Inhibition of a P-type H+ Pump

    Science.gov (United States)

    Pedersen, Jesper Torbøl; Falhof, Janus; Ekberg, Kira; Buch-Pedersen, Morten Jeppe; Palmgren, Michael

    2015-01-01

    The plasma membrane H+-ATPase is a P-type ATPase responsible for establishing electrochemical gradients across the plasma membrane in fungi and plants. This essential proton pump exists in two activity states: an autoinhibited basal state with a low turnover rate and a low H+/ATP coupling ratio and an activated state in which ATP hydrolysis is tightly coupled to proton transport. Here we characterize metal fluorides as inhibitors of the fungal enzyme in both states. In contrast to findings for other P-type ATPases, inhibition of the plasma membrane H+-ATPase by metal fluorides was partly reversible, and the stability of the inhibition varied with the activation state. Thus, the stability of the ATPase inhibitor complex decreased significantly when the pump transitioned from the activated to the basal state, particularly when using beryllium fluoride, which mimics the bound phosphate in the E2P conformational state. Taken together, our results indicate that the phosphate bond of the phosphoenzyme intermediate of H+-ATPases is labile in the basal state, which may provide an explanation for the low H+/ATP coupling ratio of these pumps in the basal state. PMID:26134563

  16. Controlling Magnetic and Ferroelectric Order Through Geometry: Synthesis, Ab Initio Theory, Characterization of New Multi-Ferric Fluoride Materials

    Energy Technology Data Exchange (ETDEWEB)

    Halasyamani, Shiv [Univ. of Houston, TX (United States); Fennie, Craig [Cornell Univ., Ithaca, NY (United States)

    2016-11-03

    We have focused on the synthesis, characterization, and ab initio theory on multi-functional mixed-metal fluorides. With funding from the DOE, we have successfully synthesized and characterized a variety of mixed metal fluoride materials.

  17. Preparation and Characterization of High-Purity Metal Fluorides for Photonic Applications

    Science.gov (United States)

    2011-01-01

    Photonics Technol. Lett., 4 446–8 (1992). 8D. F. Anderson, “ Cerium Fluoride – A Scintillator for High-Rate Applica- tions,” Nucl. Instrum. Meth. Phys... Cerium Doped Heavy Metal Fluoride Glasses, a Possible Alternative for Electromagnetic Calorimetry,” Instrum. Meth. Phys. Res. A, 380, 524–36 (1996). 10J...Preparation and Characterization of High-Purity Metal Fluorides for Photonic Applications* Wendy M. Patterson,‡,† Peter C. Stark,§ Thomas M. Yoshida

  18. DISSOLUTION OF PLUTONIUM METAL USING NITRIC ACID SOLUTIONS CONTAINING POTASSIUM FLUORIDE

    Energy Technology Data Exchange (ETDEWEB)

    Rudisill, T.; Crowder, M.; Bronikowski, M.

    2007-10-15

    The deinventory and deactivation of the Savannah River Site's (SRS's) FB-Line facility required the disposition of approximately 2000 items from the facility's vaults. Plutonium (Pu) scraps and residues which do not meet criteria for conversion to a mixed oxide fuel will be dissolved and the solution stored for subsequent disposition. Some of the items scheduled for dissolution are composite materials containing Pu and tantalum (Ta) metals. The preferred approach for handling this material is to dissolve the Pu metal, rinse the Ta metal with water to remove residual acid, and burn the Ta metal. The use of a 4 M nitric acid (HNO{sub 3}) solution containing 0.2 M potassium fluoride (KF) was initially recommended for the dissolution of approximately 500 g of Pu metal. However, prior to the use of the flowsheet in the SRS facility, a new processing plan was proposed in which the feed to the dissolver could contain up to 1250 g of Pu metal. To evaluate the use of a larger batch size and subsequent issues associated with the precipitation of plutonium-containing solids from the dissolving solution, scaled experiments were performed using Pu metal and samples of the composite material. In the initial experiment, incomplete dissolution of a Pu metal sample demonstrated that a 1250 g batch size was not feasible in the HB-Line dissolver. Approximately 45% of the Pu was solubilized in 4 h. The remaining Pu metal was converted to plutonium oxide (PuO{sub 2}). Based on this work, the dissolution of 500 g of Pu metal using a 4-6 h cycle time was recommended for the HB-Line facility. Three dissolution experiments were subsequently performed using samples of the Pu/Ta composite material to demonstrate conditions which reduced the risk of precipitating a double fluoride salt containing Pu and K from the dissolving solution. In these experiments, the KF concentration was reduced from 0.2 M to either 0.15 or 0.175 M. With the use of 4 M HNO{sub 3} and a reduction in

  19. Electrospinning of Polyvinylidene Fluoride and Polyetherimide From Mixed Solvents

    Science.gov (United States)

    Morgret, Leslie D.; Pawlowski, Kristin J.; Hinkley, Jeffrey A.

    2005-01-01

    Polyvinylidene fluoride and Ultem(TradeMark) polyetherimide were dissolved in 50/50 acetone/N,N dimethylformamide (DMF) and 80/20 tetrahydrofuran/DMF, respectively, and electrospun. Polymer solution concentrations and molecular weights were changed while other spinning parameters (voltage, distance, solution feed rate) were held constant. Fiber diameters in the resulting electrospun mats varied from 0.25 to 4.4 microns, increasing with polymer concentration and molecular weight; trends in diameter were compared with trends in viscosities and surface tensions of the spinning solutions.

  20. Preparation of high density heavy metal fluoride glasses with extended ultraviolet and infra red ranges, and such high density heavy metal fluoride glasses

    Science.gov (United States)

    Martin, Steven W. (Inventor); Huebsch, Jesse (Inventor)

    2001-01-01

    A heavy metal fluoride glass composition range (in mol percent) consisting essentially of: (16-30)BaF.sub.2.(8-26)HfF.sub.4.(6-24)InF.sub.3 or GaF.sub.3.(4-16)CdF.sub.2.(6-24)YbF.sub.3.(4-22)ZnF.sub.2. In an alternative embodiment, a heavy metal fluoride glass composition range (in mol percent) comprises (16-30)BaF.sub.2.(8-26)HfF.sub.4.(6-24) of (0-24)InF.sub.3, (0-24)GaF.sub.3 and (0-19)AlF.sub.3.(1-16)CdF.sub.2.(6-24)YbF.sub.3.(4-26)ZnF.sub.2. A preferred heavy metal fluoride glass produced in accordance with the present invention comprises a composition (in mol %) and comprises about 26BaF.sub.2.18HfF.sub.4.7InF.sub.3.5GaF.sub.3.10CdF.sub.2.18YbF.sub.3. 16ZnF.sub.2. A preferred heavy metal fluoride glass has maximum thickness of most preferably about 3 mm. Another preferred heavy metal fluoride glass comprises a composition (in mol %) and comprises about 26BaF.sub.2.18HfF.sub.4.12AlF.sub.3.10CdF.sub.2.18YbF.sub.3.16ZnF.sub.2.

  1. Oxidizing behavior of some platinum metal fluorides. [Xe complexes with Pt, Pd fluorides; Chlorine-2 oxidation by transition metal hexafluorides

    Energy Technology Data Exchange (ETDEWEB)

    Graham, L.

    1978-10-01

    The previously known compounds Xe/sub 2/F/sub 3//sup +/PtF/sub 6//sup -/, XeF/sup +/PtF/sub 6//sup -/ and XeF/sub 2/.2PtF/sub 4/(XePt/sub 2/F/sub 10/) were prepared by the interaction of XeF/sub 2/ with PtF/sub 4/. The new compounds XeF/sub 2/.PdF/sub 4/ and XeF/sub 2/.2PdF/sub 4/(XePd/sub 2/F/sub 10/) were produced by interaction of XeF/sub 2/ with either PdF/sub 4/ or Pd/sub 2/F/sub 6/. A weight loss-versus-time curve indicated the presence of 4:1, 3:1 and 2:1 XeF/sub 2//PdF/sub 4/ complexes. The thermal decomposition of XeFPtF/sub 6/ or XePd/sub 2/F/sub 10/ yields highly pure XeF/sub 4/. Thus the interaction of XeF/sub 2/ with platinum fluorides (PtF/sub 4/ or PtF/sub 5/) or palladium fluorides (Pd/sub 2/F/sub 6/ or PdF/sub 4/) provides for the conversion of XeF/sub 2/ to XeF/sub 4/. The compound XePd/sub 2/F/sub 10/ is a close structural relative of XePt/sub 2/F/sub 10/, and spectroscopic evidence suggests that both are salts of XeF/sup +/ and a polymeric (M/sub 2/F/sub 9/)/sub x//sup x-/ ion. A Xe:PtF/sub 6/ material of approximately 1:1 stoichiometry has been prepared and compared with XePdF/sub 6/(XeF/sub 2/.PdF/sub 4/). The interaction of chlorine with the third-series transition metal hexafluorides has been investigated. Gravimetric and tensimetric evidence indicate that the initial product of the Cl/sub 2/ plus IrF/sub 6/ reaction is a solid of composition Cl/sub 2/IrF/sub 6/. Vibrational spectroscopic and other evidence indicates that this solid yields a sequence of products, of which Cl/sub 3//sup +/IrF/sub 6//sup -/, Cl/sub 3//sup +/Ir/sub 2/F/sub 11//sup -/ and Ir/sub 4/F/sub 20/ have been identified, the last being the ultimate solid product of the room temperature decomposition of the adduct. A new chlorine fluoride generated in the room temperature decomposition of Cl/sub 2/IrF/sub 6/ has been tentatively formulated as Cl/sub 3/F from infrared evidence.

  2. Enhanced half-metallicity in the zigzag graphene nanoribbons by adsorption of the zigzag hydrogen fluoride molecular chains

    Directory of Open Access Journals (Sweden)

    Xue Gong

    2014-06-01

    Full Text Available A comprehensive theoretical study of the half-metallicity in the zigzag graphene nanoribbons (ZGNRs by adsorption of the zigzag hydrogen fluoride chains was presented. The ZGNR by adsorption of the hydrogen fluoride chains could be half-metallic when a critical length of the hydrogen fluoride chain is achieved on the ZGNR at low temperature. It was found that the strong dipole moments of the hydrogen fluoride chains act as the constant electric field. Our results suggest a huge possibility in spintronics device applications for achieving half-metallicity in the ZGNRs without the excessively high external electric fields.

  3. Aluminium fumarate metal-organic framework: A super adsorbent for fluoride from water

    Energy Technology Data Exchange (ETDEWEB)

    Karmakar, Sankha [Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India); Dechnik, Janina [Institut fur Anorganische Chemie und Strukturchemie, Heinrich-Heine-Universität Düsseldorf, 40204 Düsseldorf (Germany); Janiak, Christoph, E-mail: janiak@uni-duesseldorf.de [Institut fur Anorganische Chemie und Strukturchemie, Heinrich-Heine-Universität Düsseldorf, 40204 Düsseldorf (Germany); De, Sirshendu, E-mail: sde@che.iitkgp.ernet.in [Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)

    2016-02-13

    Highlights: • Maximum adsorption of fluoride on AlFu MOF occurred at 293 K. • Maximum adsorption capacity for fluoride was 600 mg/g at 293 K. • The MOF exhibited adequate charge characteristic and high surface area (1156 m{sup 2}/g). • Second order reaction and intra particle diffusion (first 1.5 h) was prevalent. • AlFu MOF exhibited high potential for fluoride removal from water. - Abstract: Potential of aluminium fumarate metal organic framework (MOF) for fluoride removal from groundwater has been explored in this work. The laboratory produced MOF exhibited characteristics similar to the commercial version. MOF was found to be micro-porous with surface area of 1156 m{sup 2}/g and average pore size 17 Å. Scanning electron micrograph of the AlFu MOF showed minute pores and texture was completely different from either of the parent materials. Change in the composition of AlFu MOF after fluoride adsorption was evident from powder X-ray diffraction analysis. Thermal stability of the AlFu MOF up to 700 K was established by thermo-gravimetric analysis. Incorporation of fluoride phase after adsorption was confirmed by X-ray fluorescence analysis. As observed from FTIR study, hydroxyl ions in AlFu MOF were substituted by fluoride. 0.75 g/l AlFu MOF was good enough for complete removal of 30 mg/l fluoride concentration in feed solution. The maximum adsorption capacity for fluoride was 600, 550, 504 and 431 mg/g, respectively, at 293, 303, 313 and 333 K.

  4. Interaction between a transition-metal fluoride and a transition-metal hydride: water-mediated hydrofluoric acid evolution following fluoride solvation.

    Science.gov (United States)

    Chierotti, Michele R; Rossin, Andrea; Gobetto, Roberto; Peruzzini, Maurizio

    2013-11-04

    The reaction between the nickel(II) PCP pincer fluoride complex ((tBu)PCP)Ni(F) [(tBu)PCP = 2,6-C6H3(CH2P(t)Bu2)2] and the tungsten(II) carbonyl hydride CpW(H)(CO)3 (Cp = η(5)-C5H5(-)) leads to hydrofluoric acid evolution and formation of the bimetallic isocarbonylic species [CpW(CO)2(μ-κ,C:κ,O-CO)···Ni((tBu)PCP)]. The process has been monitored through multinuclear ((19)F, (31)P{(1)H}, (1)H) variable-temperature NMR spectroscopy, collecting (19)F T1 data values for a fluoride ligand bound to a transition metal. The extremely short relaxation time (minimum value of 13 ms at 193 K) is ascribed to the large chemical shift anisotropy of the Ni-F bond (688 ppm). The in-depth NMR analysis has revealed that the fluoride-hydride interaction is not direct but water-mediated, at odds with what was previously observed for the "hydride-hydride" case ((tBu)PCP)Ni(H)/CpW(H)(CO)3. Kinetic measurements have unveiled that the first step of the overall mechanism is thought to be solvation of the fluoride ligand (as a result of Ni-F···H2O hydrogen bonding), while further reaction of the solvated fluoride with CpW(H)(CO)3 is extremely slow and competes with the side reaction of fluoride replacement by a water molecule on the nickel center to form the [((tBu)PCP)Ni(H2O)](+) aquo species. Finally, density functional theory analysis of the solvation process through a discrete + continuum model has been accomplished, at the M06//6-31+G(d,p) level of theory, to support the mechanistic hypothesis.

  5. [Concentration of fluoride in mixed saliva of patients with end-stage renal disease undergoing renal replacement therapy].

    Science.gov (United States)

    Gorbaczewski, Andrzej; Buczkowska-Radlińska, Jadwiga; Chlubek, Dariusz; Noceń, Iwona; Samujło, Dorota; Trusewicz, Matylda

    2004-01-01

    This study was carried out on 48 patients with ESRD undergoing hemodialysis treatment (29 males and 19 females, mean age 50.8 years) and renal transplantation (15 females and 33 males, mean age 42.2 years). The results were compared with a group of 44 healthy persons (23 females and 21 males, mean age 49.5 years). The aim of our investigation was to examine the content of fluoride in the mixed unstimulated saliva of the patients undergoing renal replacement therapy and in the control group of healthy persons. We studied the influence of hemodialysis on saliva fluoride levels. Saliva samples were collected by the spitting method according to Navazesh. Samples were collected before and after hemodialysis session and once in graft recipients and controls. Fluoride concentrations were determined with an Orion fluoroselective electrode model 96-09. The fluoride level in healthy persons was 4.92 +/- 2.30 micromol/L. Before hemodialysis, the mean fluoride level was 9.63 +/- 3.90 micromol/L and decreased significantly to 7.52 +/- 2.71 micromol/L after hemodialysis (p < 0.0001). Saliva content of fluorides in patients before and after hemodialysis was significantly higher than in healthy subjects and kidney graft recipients (p < 0.0001). There was no significant difference in fluoride concentration between patients after kidney transplantation and controls. The results suggest the need for individual fluoride supplementation in chronically hemodialysed patients.

  6. Correlation among fluoride and metals in irrigation water and soils of Ethiopian Rift Valley

    Directory of Open Access Journals (Sweden)

    Elias Gizaw

    2014-05-01

    Full Text Available The levels of fluoride and selected metals in Ethiopian Rift Valley soils and irrigation water in the nearby sources were determined by fluoride ion selective electrode and flame atomic absorption spectrophotometer, respectively. The pH, conductivity, salinity and total dissolved solids in water and soil samples were also determined. Accuracy of the optimized procedure was evaluated using standard addition (spiking method and an acceptable percentage recovery was obtained. The fluoride concentrations in water samples were found in the range of 0.14-8.0 mg/L which is below the WHO limit of fluoride concentration for irrigation (less than 10 mg/L. The water soluble and total fluorides in soil were 2.3-16 µg/g and 209-1210 µg/g, respectively and are within the ranges recommended by FAO and WHO. The range of metal concentration in soil samples (µg/g dry weight basis and in water samples (mg/L respectively were: Na (684-6703, 8.6-67, Mg (1608-11229, 23-67, K (1776-4394, 1.1-20, Ca (7547-22998, 17-267, Cr (9.8-79, 0.07-0.17, Mn (143-700, 0.05-37, Co (50-112, 0.35-1.5, Ni (446-1288, 0.27-41, Fe (12180-32681, 6.0-48, Cu (8.9-45, 0.09-0.25 and Zn (31-89, 0.14-0.56. Fluoride was found to have significant correlation with major trace metals (Fe, Cu and Cr, but the correlation with other trace metals was not significant. DOI: http://dx.doi.org/10.4314/bcse.v28i2.7

  7. Stabilization of fluoroindate glasses by magnesium fluoride and other heavy metal fluorides

    Directory of Open Access Journals (Sweden)

    B. J. Costa

    1998-06-01

    Full Text Available Their extended transparency in the IR makes them attractive for use as optical fibers for CO laser power delivery and optical amplification. This paper firstly describes the spectacular stabilizing effect of MgF2 on the binary system InF3-BaF2. The investigation of the InF3-BaF2-MgF2 system led to samples up to 5mm in thickness. Further optimization of this system was achieved by incorporation of limited amounts of other fluorides and resulted in increased resistence to devitrification. The second approach of this work was concerned to the investigation of the pseudo-ternary system InF3-GdF3-GaF3 at constant concentrations of ZnF2-SrF2-BaF2-NaF. Several compositions were studied in this system. The samples presented a better thermal stability when compared to other families of fluoride glasses. Therefore, these glasses seem to be very promising for the fabrication of special optical fibers. Thermal data are reported.

  8. Mixing Metals in the Early Universe

    CERN Document Server

    Ferrara, A; Shchekinov, Yu A; Ferrara, Andrea; Pettini, Max; Shchekinov, Yuri

    2000-01-01

    We investigate the evolution of the metallicity of the intergalactic medium (IGM) with particular emphasis on its spatial distribution. We propose that metal enrichment occurs as a two step process. First, supernova (SN) explosions eject metals into relatively small regions confined to the surroundings of star-forming galaxies. From a comprehensive treatment of blowout we show that SNae by themselves fail by more than one order of magnitude to distribute the products of stellar nucleosynthesis over volumes large enough to pollute the whole IGM to the metallicity levels observed. Thus, a additional (but as yet unknown) physical mechanism must be invoked to mix the metals on scales comparable to the mean distance between the galaxies which are most efficient pollutants. From this simple hypothesis we derive a number of testable predictions for the evolution of the IGM metallicity. Specifically, we find that: (i) the fraction of metals ejected over the star formation history of the universe is about 50% at z=0; ...

  9. Evaluation of hydrogenation properties on MgHx-transition metal fluoride composites by planetary ball milling

    Science.gov (United States)

    Jang, Min-Hyuk; Park, So-Hyun; Kim, Whan-Gi; Hong, Tae-Whan

    2015-11-01

    To improve the disadvantages of Mg hydrides, a few studies were conducted for MgHx intermixed with transition metal fluorides. MgF2 formed from the MgHx-transition metal fluoride system can be replaces the initial surface oxide layer and provides a reactive and protective fluorinated surface for for hydrogen uptake. Thus, the absorption/desorption kinetics will be enhanced. In this research, MgHx-transition metal fluoride composites mixture has been prepared by hydrogen induced planetary ball milling. The synthesized powders were characterized by X-ray diffraction analysis, scanning electron microscopy and simultaneous thermogravimetric, differential scanning calorimetric analysis. The hydrogenation behaviors were evaluated by using a sievert's type automatic pressure-composition-temperature apparatus without any activation treatment. From the characteristics of the absorption kinetics and curves observed, the role of transition metal fluoride was catalyst in hydrogen absorption. The results of Pressure-Composition Isotherm curve, available hydrogen storage amount for MgHx-5 vol% CoF2 composites were 4.85 wt%, for MgHx-5 vol%TiF3 composites were 4.88 wt%. at 623K in the 5th cycle.

  10. An exposure and risk assessment for fluoride and trace metals in black tea

    Energy Technology Data Exchange (ETDEWEB)

    Sofuoglu, Sait C. [Izmir Institute of Technology, Department of Chemical Engineering and Environmental Research Center, Guelbahce, Urla 35430 Izmir (Turkey)], E-mail: cemilsofuoglu@iyte.edu.tr; Kavcar, Pinar [Izmir Institute of Technology, Department of Chemical Engineering and Environmental Research Center, Guelbahce, Urla 35430 Izmir (Turkey)], E-mail: pinarkavcar@iyte.edu.tr

    2008-10-30

    Exposure and associated health risks for fluoride and trace metals in black tea were estimated. Fifty participants were randomly recruited to supply samples from the tea that they drink, and self-administer a questionnaire that inquired about personal characteristics and daily tea intake. Analyzed trace metals included aluminum, arsenic, barium, cadmium, cobalt, chromium, copper, manganese, nickel, strontium, and zinc. Fluoride and four metals (Al, Cr, Mn, Ni) were detected in all samples while barium was detected only in one sample. The remaining metals were detected in >60% of the samples. Fluoride and aluminum levels in instant tea bag samples were greater than in loose tea samples (p < 0.05) while the differences in elemental concentrations of loose and pot bag tea samples were not significant. Median and 90th percentile daily tea intake rates were estimated as 0.35 and 1.1 l/day, respectively. Neither fluoride nor aluminum levels in black tea were found to associate with considerable risks of fluorosis and Alzheimer's disease, respectively. However, carcinogenic risk levels for arsenic were high; R > 1.0 x 10{sup -6} even at the median level. According to sensitivity analysis, daily tea intake was the most influencing variable to the risk except for arsenic for which the concentration distribution was of more importance.

  11. Mechanochemical synthesis, structure, and properties of solid solutions of alkaline earth metal fluorides: Ma1-xMbxF2 (M: Ca, Sr, Ba)

    Science.gov (United States)

    Heise, M.; Scholz, G.; Düvel, A.; Heitjans, P.; Kemnitz, E.

    2016-10-01

    The capability of mechanochemical synthesis for the formation of solid solutions of alkaline earth metal fluorides Ma1-xMbxF2 (M: Ca, Sr, Ba) was tested by fluorination of metal acetates and metal hydroxides with ammonium fluoride directly at milling. Evidence was found for a mutual substitution of cations on their lattice positions in Ca1-xSrxF2 and Ba1-xSrxF2 samples. For the Ba/Ca-system this synthesis route is only partially successful. X-ray diffraction and 19F MAS NMR spectroscopy were used to characterize all samples concerning their crystal structure and local fluorine coordination. Calculations of 19F chemical shifts with the superposition model along with probability calculations for the intensity of the individual 19F lines, performed in dependence on the molar composition of the samples, perfectly agree with the experimental findings. The fluoride ion conductivity of as-prepared samples, determined by temperature dependent DC conductivity measurements, is significantly higher than those of crystalline binary fluorides. Moreover, a higher F- ion conductivity is observed for samples with higher mixing grade in the Ca/Sr-and the Ba/Sr-systems.

  12. Stabilization of Th 3+ ions into mixed-valence thorium fluoride

    Science.gov (United States)

    Dubois, Marc; Dieudonné, Belto; Mesbah, Adel; Bonnet, Pierre; El-Ghozzi, Malika; Renaudin, Guillaume; Avignant, Daniel

    2011-01-01

    The unusual oxidation state +3 of the thorium has been stabilized into a lithium containing non-stoichiometric mixed-valence (III/IV) thorium fluorinated phase with formula Li 2+ xTh 12F 50 (0afore mentioned single phase may be considered as an insertion compound. The Li + insertion is accompanied by the simultaneous reduction of a part of the Th 4+ ions, resulting in a mixed-valence III/IV thorium fluoride. The electrochemical insertion of Li + ions into the open channels of the host matrix has been carried out at 60 °C, using an alkylcarbonate PC-LiClO 4 1 M electrolyte. The Li + and Th 3+ contents, both in the starting composition and the Li + inserted ones, were investigated by high resolution solid state 7Li NMR and EPR, respectively.

  13. Preparation of uniform nanoparticles of ultra-high purity metal oxides, mixed metal oxides, metals, and metal alloys

    Science.gov (United States)

    Woodfield, Brian F.; Liu, Shengfeng; Boerio-Goates, Juliana; Liu, Qingyuan; Smith, Stacey Janel

    2012-07-03

    In preferred embodiments, metal nanoparticles, mixed-metal (alloy) nanoparticles, metal oxide nanoparticles and mixed-metal oxide nanoparticles are provided. According to embodiments, the nanoparticles may possess narrow size distributions and high purities. In certain preferred embodiments, methods of preparing metal nanoparticles, mixed-metal nanoparticles, metal oxide nanoparticles and mixed-metal nanoparticles are provided. These methods may provide tight control of particle size, size distribution, and oxidation state. Other preferred embodiments relate to a precursor material that may be used to form nanoparticles. In addition, products prepared from such nanoparticles are disclosed.

  14. Cerium doped heavy metal fluoride glasses, a possible alternative for electromagnetic calorimetry

    CERN Document Server

    Auffray, Etiennette; Dafinei, I; Fay, J; Lecoq, P; Mares, J A; Martini, M; Mazé, G; Meinardi, F; Moine, B; Nikl, M; Pédrini, C; Poulain, M; Schneegans, M; Tavernier, Stefaan; Vedda, A

    1996-01-01

    The article is an overview of the research activity performed in the framework of the Crystal Clear Collaboration to produce scintillating glasses. The manufacturing of heavy metal fluoride glasses doped with Ce3+ is discussed. The luminescence and scintillation characteristics as well as the radiation hardness properties are extensively studied in the case of Ce doped fluorohafnate , found to be the most convenient glass scintillator for high energy physics applications.

  15. Improved Pr{sup 3+}-doped heavy metal fluoride glasses and fibers

    Energy Technology Data Exchange (ETDEWEB)

    Fajardo, J.; Sigel, G.H. Jr. [Rutgers Univ., Piscataway, NJ (United States)

    1996-12-31

    Praseodymium doped heavy metal fluoride glass preforms were fabricated via a modified suction casting method. A subsequent redraw process was employed to obtain high quality single mode fluoride fiber. Modifications of the ZBLAN composition, including the incorporation of In{sup 3+}, Y{sup 3+} and Cs{sup +}, were undertaken in an attempt to improve optical properties while maintaining the inherent drawability of ZBLAN. Thermal analysis to determine the various draw parameters was conducted using Differential Scanning Calorimetry, while optical characterization included spectral absorption, fluorescence, and fluorescent lifetime measurements for all specimens. The modifications in composition resulted in an increase in the fluorescent lifetime of Pr{sup 3+} at 1.3{mu}m.

  16. Investigation of metal fluoride thermal energy storage materials: availability, cost, and chemistry. Final report, July 15, 1976--December 15, 1976

    Energy Technology Data Exchange (ETDEWEB)

    Eichelberger, J.L.

    1976-12-01

    Storage of thermal energy in the 400 to 1000/sup 0/C range is attracting increasing consideration for use in solar power, central power, vehicular, and commercial process systems. This study investigates the practicality of using metal fluorides as the heat storage medium. The projected availability of metal fluorides has been studied and is shown to be adequate for widespread thermal storage use. Costs are projected and discussed in relation to thermal energy storage applications. Phase diagrams, heats of fusion, heat capacities, vapor pressures, toxicity, stability, volume changes, thermal conductivities, fusion kinetics, corrosion, and container materials of construction for a wide range of fluorides have been examined. Analyses of these data in consideration of thermal energy storage requirements have resulted in selection of the most cost-effective fluoride mixture for each of 23 temperature increments between 400 and 1000/sup 0/C. Thermo-physical properties of these 23 materials are presented. Comparison of fluoride with non-fluoride materials shows that the fluorides are suitable candidates for high temperature applications on the bases of cost, heat capacity/unit volume, heat capacity/unit weight, corrosive properties, and availability.

  17. Preparation of uniform mixed metal oxide and superconductive oxides

    Energy Technology Data Exchange (ETDEWEB)

    Barder, T.J.

    1991-04-30

    This paper describes a method for producing a uniform mixed metal oxide. It includes dissolving metals as their salts of a carboxylic acid in an aliphatic alcohol in the substantial absence of water, the metals are in the same proportions as in the corresponding mixed metal oxide; co-precipitating the metals as their oxalates by mixing the alcohol solution with oxalic acid; separating the co-precipitated metal oxalates and calcining the oxalates in air or oxygen above about 500{degrees} C to convert the oxalates to the corresponding metal oxides.

  18. Fluoride adsorption studies on mixed-phase nano iron oxides prepared by surfactant mediation-precipitation technique

    Energy Technology Data Exchange (ETDEWEB)

    Mohapatra, M., E-mail: mamatamohapatra@yahoo.com [Institute of Minerals and Materials Technology, Acharyavihar, Bhubaneswar 751 013, Orissa (India); Rout, K. [Institute of Minerals and Materials Technology, Acharyavihar, Bhubaneswar 751 013, Orissa (India); Singh, P. [Murdoch University, Perth, Western Australia (Australia); Anand, S. [Institute of Minerals and Materials Technology, Acharyavihar, Bhubaneswar 751 013, Orissa (India); Layek, S.; Verma, H.C. [Indian Institute of Technology, Kanpur (India); Mishra, B.K. [Institute of Minerals and Materials Technology, Acharyavihar, Bhubaneswar 751 013, Orissa (India)

    2011-02-28

    Mixed nano iron oxides powder containing goethite ({alpha}-FeOOH), hematite ({alpha}-Fe{sub 2}O{sub 3}) and ferrihydrite (Fe{sub 5}HO{sub 8}.4H{sub 2}O) was synthesized through surfactant mediation-precipitation route using cetyltrimethyl ammonium bromide (CTAB). The X-ray diffraction, FTIR, TEM, Moessbauer spectroscopy were employed to characterize the sample. These studies confirmed the nano powder contained 77% goethite, 9% hematite and 14% ferrihydrite. Fluoride adsorption onto the synthesized sample was investigated using batch adsorption method. The experimental parameters chosen for adsorption studies were: pH (3.0-10.0), temperature (35-55 deg. C), concentrations of adsorbent (0.5-3.0 g/L), adsorbate (10-100 mg/L) and some anions. Adsorption of fluoride onto mixed iron oxide was initially very fast followed by a slow adsorption phase. By varying the initial pH in the range of 3.0-10.0, maximum adsorption was observed at a pH of 5.75. Presence of either SO{sub 4}{sup 2-} or Cl{sup -} adversely affected the adsorption of fluoride in the order of SO{sub 4}{sup 2-} > Cl{sup -}. The FTIR studies of fluoride loaded adsorbent showed that partly the adsorption on the surface took place at surface hydroxyl sites. Moessbauer studies indicated that the overall absorption had gone down after fluoride adsorption that implies it has reduced the crystalline bond strength. The relative absorption area of ferrihydrite was marginally increased from 14 to 17%.

  19. Fluoride adsorption studies on mixed-phase nano iron oxides prepared by surfactant mediation-precipitation technique.

    Science.gov (United States)

    Mohapatra, M; Rout, K; Singh, P; Anand, S; Layek, S; Verma, H C; Mishra, B K

    2011-02-28

    Mixed nano iron oxides powder containing goethite (α-FeOOH), hematite (α-Fe(2)O(3)) and ferrihydrite (Fe(5)HO(8)·4H(2)O) was synthesized through surfactant mediation-precipitation route using cetyltrimethyl ammonium bromide (CTAB). The X-ray diffraction, FTIR, TEM, Mössbauer spectroscopy were employed to characterize the sample. These studies confirmed the nano powder contained 77% goethite, 9% hematite and 14% ferrihydrite. Fluoride adsorption onto the synthesized sample was investigated using batch adsorption method. The experimental parameters chosen for adsorption studies were: pH (3.0-10.0), temperature (35-55°C), concentrations of adsorbent (0.5-3.0 g/L), adsorbate (10-100 mg/L) and some anions. Adsorption of fluoride onto mixed iron oxide was initially very fast followed by a slow adsorption phase. By varying the initial pH in the range of 3.0-10.0, maximum adsorption was observed at a pH of 5.75. Presence of either SO(4)(2-) or Cl(-) adversely affected the adsorption of fluoride in the order of SO(4)(2-)>Cl(-). The FTIR studies of fluoride loaded adsorbent showed that partly the adsorption on the surface took place at surface hydroxyl sites. Mössbauer studies indicated that the overall absorption had gone down after fluoride adsorption that implies it has reduced the crystalline bond strength. The relative absorption area of ferrihydrite was marginally increased from 14 to 17%. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. Ab Initio Calculation of 19F NMR Chemical Shielding for Alkaline-earth-metal Fluorides

    Institute of Scientific and Technical Information of China (English)

    CAI,Shu-Hui(蔡淑惠); CHEN,Zhong,(陈忠); LU,Xin(吕鑫); CHEN,Zhi-Wei(陈志伟); WAN,Hui-Lin(万惠霖)

    2001-01-01

    Gauge-independent atomic orbital (GIAO) method atHartree-Fock (HF) and density functional theory (DFr) lev-els,respectively,was employed to calculate 19F NMR chemi-cal shieldings of solid state alkaline-earth-metal fluorides MF2 (M = Mg,Ca,Sr,Ba).The results show that,although thecalculated19F chemical shieldings tend to be larger than the experinental values,they have a fairly good linear relation-ship with the observed ones.The calculated results based on different combinations of basis sets show that the B3LYP (ahybrid of DFT with HF) predictions are greatly superior tothe I-IF predictions.When a basis set of metal atom with ef- fecfive core potential (ECP) has well representation of valencewavefunction,especially wavefuncfion of d component,andproper definition of core electron nmnher,it can be applied toobtain 19F chemical shielding which is dose to that of all-elec-tron calculation.Tne variation of 19F chemical shielding of al-kaline-earth-metal fluorides correlates well with the latticefactor A/R2.``

  1. Relationship between Compostion,Density and Refractive Index for Heavy Metal Fluoride Glasses

    Institute of Scientific and Technical Information of China (English)

    ShaukatS.F; HobsonP.R.; 等

    2001-01-01

    The density and the refractive index for various compositions of heavy metal fluoride(HMF) glasses,used to make low-loss optical wave-guides,have been measured by standard archimedes method and by using as Pulfrich refrctometer respectively.The density as a function of composition is calculated considering the effective volume of the ions contained in the glass to be invariant.The refractive index as a function of composition is also calcuated.based on the Lorenz-Lorentz equation,by computing the electronic polarizability of HMF glasses.All calculated results are in good agreement with the observed data.

  2. The study of devitrification processes in heavy-metal fluoride glasses.

    Science.gov (United States)

    Dunkley, Ian R; Smith, Reginald W; Varma, Sudhanshu

    2004-11-01

    Heavy-metal fluoride glasses are very promising optical fiber materials because of their predicted ultralow loss and long transparency range. Although conventional silica fibers have attained their theoretical minimum loss of 0.15 dB/km, fluoride glasses have the potential to yield losses of only 0.001 dB/km. Fluoride glasses also exhibit transparency into mid-IR frequencies, a region inaccessible to silica fibers. However, this group of glasses is very unstable to devitrification during both bulk glass synthesis and fiber-drawing. This instability has limited their commercial exploitation to a small niche market in the laser industry. The ZBLAN glass (53ZrF(4)-20BaF(2)-4LaF(3)-3AlF(3)-20NaF) is the most promising of these materials since its fiber-drawing region lies on the edge, or possibly just outside its crystallization region. It is believed that additional research into understanding the nucleation mechanics involved in the devitrification of fluoride glasses will lead to the development of technology to suppress such nucleation, or at least minimize the associated crystallization temperature region, allowing high optical quality fibers to be produced. It has recently been demonstrated that a microgravity environment can suppress devitrification in ZBLAN glass preform preparation, and that devitrification may be reduced when preparing ZBLAN terrestrially in a containerless facility. It is believed that the role of viscosity is critical in the devitrification mechanism of ZBLAN glass and in determining the optimum fiber-drawing temperature. Unfortunately, viscosity data for fluoride glasses are only available above the melting point and around the glass transition. A piezoelectric viscometer has been developed and is being used to determine the missing viscosity data in the fiber-drawing and crystallization temperature regions. Shear thinning of the glasses and/or the application of hydrostatic pressure on the glasses have been recently proposed to be

  3. Apparent Molal Volumes of Sodium Fluoride in Mixed Aqueous-Ethanol Solvents

    Directory of Open Access Journals (Sweden)

    E. Gomaa

    2010-09-01

    Full Text Available The densities of different molal concentrations of sodium fluoride at ethanol-water mixtures, as solvent, have been measured over the whole composition range at three different temperatures, 293.15, 303.15 and 313.15oK. From the measured densities, the apparent and limiting molal volumes of the electrolytes have been evaluated. The limiting molal volumes for sodium and fluoride ions were estimated by splitting the ionic contributions as an asymmetric assumption.

  4. A new approach to prepare nanoscopic rare earth metal fluorides: the fluorolytic sol-gel synthesis of ytterbium fluoride.

    Science.gov (United States)

    Schmidt, L; Dimitrov, A; Kemnitz, E

    2014-06-25

    A new approach for the preparation of approx. 5 nm sized ytterbium fluoride nanoparticles based on the fluorolytic sol-gel route is reported. DLS, TEM, IR and XRD were used to characterize the particles as well as the aging behavior of the sols. Furthermore, a new Yb(III) complex was isolated from the precursor solution and characterized by X-ray single crystal structure determination.

  5. Perspectives on Li and transition metal fluoride phosphates as cathode materials for a new generation of Li-ion batteries

    Directory of Open Access Journals (Sweden)

    Evgeny V. Antipov

    2015-01-01

    Full Text Available To satisfy the needs of rapidly growing applications, Li-ion batteries require further significant improvements of their key properties: specific energy and power, cyclability, safety and costs. The first generation of cathode materials for Li-ion batteries based on mixed oxides with either spinel or rock-salt derivatives has already been widely commercialized, but the potential to improve the performance of these materials further is almost exhausted. Li and transition metal inorganic compounds containing different polyanions are now considered as the most promising cathode materials for the next generation of Li-ion batteries. Further advances in cathode materials are considered to lie in combining different anions [such as (XO4n− and F−] in the anion sublattice, which is expected to enhance the specific energy and power of these materials. This review focuses on recent advances related to the new class of cathode materials for Li-ion batteries containing phosphate and fluoride anions. Special attention is given to their crystal structures and the relationships between structure and properties, which are important for their possible practical applications.

  6. Perspectives on Li and transition metal fluoride phosphates as cathode materials for a new generation of Li-ion batteries.

    Science.gov (United States)

    Antipov, Evgeny V; Khasanova, Nellie R; Fedotov, Stanislav S

    2015-01-01

    To satisfy the needs of rapidly growing applications, Li-ion batteries require further significant improvements of their key properties: specific energy and power, cyclability, safety and costs. The first generation of cathode materials for Li-ion batteries based on mixed oxides with either spinel or rock-salt derivatives has already been widely commercialized, but the potential to improve the performance of these materials further is almost exhausted. Li and transition metal inorganic compounds containing different polyanions are now considered as the most promising cathode materials for the next generation of Li-ion batteries. Further advances in cathode materials are considered to lie in combining different anions [such as (XO4) (n-) and F(-)] in the anion sublattice, which is expected to enhance the specific energy and power of these materials. This review focuses on recent advances related to the new class of cathode materials for Li-ion batteries containing phosphate and fluoride anions. Special attention is given to their crystal structures and the relationships between structure and properties, which are important for their possible practical applications.

  7. Erosion protection comparison of stabilised SnF2 , mixed fluoride active and SMFP/arginine-containing dentifrices.

    Science.gov (United States)

    Eversole, Sandra L; Saunders-Burkhardt, Kymberly; Faller, Robert V

    2014-03-01

    To investigate the relative erosion protection potential of marketed dentifrices formulated with either stabilised stannous fluoride (SnF2 ), sodium fluoride (NaF) and/or sodium monofluorophosphate (SMFP) using an established laboratory erosion cycling model. Sound enamel cores from extracted, human enamel were cleaned, ground and polished, soaked in pooled saliva (pellicle formation) and treated with a 1:3 slurry of dentifrice and saliva. Specimens were subjected to daily challenges with 1% citric acid, a potentially damaging acid found in common food and drinks. Marketed dentifrices compared were: (1) a stabilised stannous fluoride product formulated with 1,100 ppm F as SnF2 ; (2) a cavity protection product containing 1,100 ppm F as NaF; (3) a cavity protection product comprising a mixed active fluoride system with 1,000 ppm F as SMFP + 450 ppm F as NaF; and (4) a sensitivity product containing 1,450 ppm F as SMFP + 8% arginine bicarbonate. Specimens from Group 1 demonstrated an average loss of 5.5 (±1.2) μm of tooth surface enamel; Groups 2, 3 and 4 lost an average of 18.3 (±0.9) μm, 16.0 (±2.0) μm and 17.1 (±1.1) μm, respectively, of tooth surface enamel. Group 1 provided a statistically significant difference in protection compared with the other products. These results suggest that the marketed dentifrice formulated with stabilised SnF2 may provide enhanced protection of exposed tooth surfaces against dietary acid attack compared with the other products tested. © 2014 FDI World Dental Federation.

  8. Highly sensitive and selective fluoride detection in water through fluorophore release from a metal-organic framework.

    Science.gov (United States)

    Hinterholzinger, Florian M; Rühle, Bastian; Wuttke, Stefan; Karaghiosoff, Konstantin; Bein, Thomas

    2013-01-01

    The detection, differentiation and visualization of compounds such as gases, liquids or ions are key challenges for the design of selective optical chemosensors. Optical chemical sensors employ a transduction mechanism that converts a specific analyte recognition event into an optical signal. Here we report a novel concept for fluoride ion sensing where a porous crystalline framework serves as a host for a fluorescent reporter molecule. The detection is based on the decomposition of the host scaffold which induces the release of the fluorescent dye molecule. Specifically, the hybrid composite of the metal-organic framework NH2-MIL-101(Al) and fluorescein acting as reporter shows an exceptional turn-on fluorescence in aqueous fluoride-containing solutions. Using this novel strategy, the optical detection of fluoride is extremely sensitive and highly selective in the presence of many other anions.

  9. Conversion Reaction Mechanisms in Lithium Ion Batteries: Study of the Binary Metal Fluoride Electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Feng; Robert, Rosa; Chernova, Natasha A.; Pereira, Nathalie; Omenya, Fredrick; Badway, Fadwa; Hua, Xiao; Ruotolo, Michael; Zhang, Ruigang; Wu, Lijun; Volkov, Vyacheslav; Su, Dong; Key, Baris; Whittingham, M. Stanley; Grey, Clare P.; Amatucci, Glenn G.; Zhu, Yimei; Graetz, Jason (Binghamton); (Rutgers); (BNL); (Cambridge); (SBU)

    2015-10-15

    Materials that undergo a conversion reaction with lithium (e.g., metal fluorides MF{sub 2}: M = Fe, Cu, ...) often accommodate more than one Li atom per transition-metal cation, and are promising candidates for high-capacity cathodes for lithium ion batteries. However, little is known about the mechanisms involved in the conversion process, the origins of the large polarization during electrochemical cycling, and why some materials are reversible (e.g., FeF{sub 2}) while others are not (e.g., CuF{sub 2}). In this study, we investigated the conversion reaction of binary metal fluorides, FeF{sub 2} and CuF{sub 2}, using a series of local and bulk probes to better understand the mechanisms underlying their contrasting electrochemical behavior. X-ray pair-distribution-function and magnetization measurements were used to determine changes in short-range ordering, particle size and microstructure, while high-resolution transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) were used to measure the atomic-level structure of individual particles and map the phase distribution in the initial and fully lithiated electrodes. Both FeF{sub 2} and CuF{sub 2} react with lithium via a direct conversion process with no intercalation step, but there are differences in the conversion process and final phase distribution. During the reaction of Li{sup +} with FeF{sub 2}, small metallic iron nanoparticles (<5 nm in diameter) nucleate in close proximity to the converted LiF phase, as a result of the low diffusivity of iron. The iron nanoparticles are interconnected and form a bicontinuous network, which provides a pathway for local electron transport through the insulating LiF phase. In addition, the massive interface formed between nanoscale solid phases provides a pathway for ionic transport during the conversion process. These results offer the first experimental evidence explaining the origins of the high lithium reversibility in FeF{sub 2}. In contrast

  10. Separating and recycling metals from mixed metallic particles of crushed electronic wastes by vacuum metallurgy.

    Science.gov (United States)

    Zhan, Lu; Xu, Zhenming

    2009-09-15

    During the treatment of electronic wastes, a crushing process is usually used to strip metals from various base plates. Several methods have been applied to separate metals from nonmetals. However, mixed metallic particles obtained from these processes are still a mixture of various metals, including some toxic heavy metals such as lead and cadmium. With emphasis on recovering copper and other precious metals, there have hitherto been no satisfactory methods to recover these toxic metals. In this paper, the criterion of separating metals from mixed metallic particles by vacuum metallurgy is built. The results show that the metals with high vapor pressure have been almost recovered completely, leading to a considerable reduction of environmental pollution. In addition, the purity of copper in mixed particles has been improved from about 80 wt % to over 98 wt %.

  11. Applications of Metal/Mixed Metal Oxides as Photocatalyst: (A Review

    Directory of Open Access Journals (Sweden)

    Avnish Kumar Arora

    2016-08-01

    Full Text Available Metal oxides/ Mixed metal oxides have wide applications as catalyst, Adsorbents, Superconductors, semiconductors, ceramics, antifungal agents and also have spacious applications in medicines. This review article is focused on their applications as photocatalyst in various organic reactions.

  12. Metal Fluoride Inhibition of a P-type H+ Pump: STABILIZATION OF THE PHOSPHOENZYME INTERMEDIATE CONTRIBUTES TO POST-TRANSLATIONAL PUMP ACTIVATION

    National Research Council Canada - National Science Library

    Pedersen, Jesper Torbøl; Falhof, Janus; Ekberg, Kira; Buch-Pedersen, Morten Jeppe; Palmgren, Michael

    2015-01-01

    .... In contrast to findings for other P-type ATPases, inhibition of the plasma membrane H(+)-ATPase by metal fluorides was partly reversible, and the stability of the inhibition varied with the activation state...

  13. Sol-Gel/Hydrothermal Synthesis of Mixed Metal Oxide

    African Journals Online (AJOL)

    Mixed metal oxides of titanium and zinc nanocomposites were prepared through sol-gel method under hydrothermal ... the production of TiO -ZnO nanoparticles use. 2 either titanium ... involved using titanium sulphate and thioacetamide for ...

  14. The Effects of Gravity on the Crystallization Behavior of Heavy Metal Fluoride Glasses

    Science.gov (United States)

    Tucker, Dennis S.; Smith, Guy A.

    2004-01-01

    Heavy metal fluoride glasses are used in such applications as fiber lasers and laser amplifiers. ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) is one of the more commonly used heavy metal fluoride glasses. ZBLAN is an infrared transmitter and has a theoretical attenuation coefficient of 0.002 db/km. However, due to impurities and small crystallites this attenuation coefficient has not been achieved to date. ZBLAN is a fragile glass which can lead to rapid crystallization, if the glass is not cooled rapidly to below the glass transition temperature or if the glass is reheated near the crystallization temperature for any period of time. Studies carried on at Marshall Space Flight Center and the University of Alabama in Huntsville since 1993 have shown that heating ZBLAN glass at the crystallization temperature in reduced gravity results in a suppression of crystallization when compared to ZBLAN processed in unit gravity. These studies utilized NASA's KC-135 aircraft and the Conquest sounding rocket. In the first series of experiments, short lengths of ZBLAN fiber were heated to the crystallization temperature in reduced gravity on board the KC- 135 and the Conquest sounding rocket and compared with fibers heated in unit gravity. The fibers processed in reduced gravity showed no evidence of crystallization when studied with x-ray diffraction and scanning electron microscopy. However, the fibers processed in unit gravity were completely crystallized. Subsequent experiments included heating small pieces of ZBLAN glass at the crystallization temperature while viewing with a video camera to follow the crystallization phenomenon. In this experiment crystallization was observed in reduced gravity, however, it was suppressed when compared to heating in unit gravity. In the most recent experiment on board the KC-135, rapid thermal analysis of ZBLAN was performed. A mechanism to explain the observations has been proposed. This mechanism is based on shear thinning whereby, the glass

  15. Dispersive mirrors designed with mixed metal multilayer dielectric stacks

    Institute of Scientific and Technical Information of China (English)

    Jinlong Zhang; Zhanshan Wang; Xinbin Cheng

    2012-01-01

    A different approach to construct dispersive mirrors (DMs) for ultrafast applications is proposed based on the high reflectivity and constant phase property of a novel metal in ultrawide spectral band.A 200-nm bandwidth DM,a high dispersive DM,and a complementary DM are designed with mixed metal multilayer dielectric stacks.The results show that the mixed-metal multilayer dielectric DMs (MMDMs)have much less layers and total thickness compared with an all-dielectric DM under the case of comparable performance.Such an approach will save manufacturing time and remarkably improve the stress of the DM.

  16. Excellent fluoride decontamination and antibacterial efficacy of Fe-Ca-Zr hybrid metal oxide nanomaterial.

    Science.gov (United States)

    Dhillon, Ankita; Nair, Manjula; Bhargava, Suresh K; Kumar, Dinesh

    2015-11-01

    The aim of the present study is to develop an efficient nanomaterial for the removal of fluoride and disinfection of harmful bacteria in order to make water potable according to Environmental Protection Agency (EPA) guidelines. Hydrous hybrid Fe-Ca-Zr oxide nanoadsorbent presented a marked fluoride adsorption capacity of 250 mg/g at pH 7.0 (±0.1) much greater than other commercially accessible adsorbents for both synthetic and real water samples. The adsorption isotherms, Freundlich and Dubinin-Radushkevich (D-R) fitted reasonably well fine having high coefficient of regression values. The adsorption of fluoride was established well using pseudo-second-order kinetics. The fluoride loaded adsorbent was efficiently regenerated by using an alkali solution. Interestingly, the developed nanomaterial not only showed excellent fluoride removal capacity but also demonstrated good antibacterial activity against Escherichia coli with IC50 (25 μg/mL). Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Computational screening of mixed metal halide ammines

    DEFF Research Database (Denmark)

    Jensen, Peter Bjerre; Lysgaard, Steen; Quaade, Ulrich

    Metal halide ammines, e.g. Mg(NH3)6Cl2 and Sr(NH3)8Cl2, can reversibly store ammonia, with high volumetric hydrogen storage capacities. The storage in the halide ammines is very safe, and the salts are therefore highly relevant as a carbon-free energy carrier in future transportation infrastructure...

  18. Colorimetric determination of the fluoride ion - application to uranium metal and to uranous fluoride; Dosage colorimetrique de l'ion fluor - application a l'uranium metal et au fluorure uraneux

    Energy Technology Data Exchange (ETDEWEB)

    Hering, H.; Hure, J.; Legrand, S. [Commissariat a l' Energie Atomique (France)

    1949-12-01

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

  19. Preparation of conversion coating on Ti-6Al-4V alloy in mixed solution of phytic acid and ammonium fluoride through chemical modification

    Science.gov (United States)

    Li, Lanlan; He, Jian; Yang, Xu

    2016-05-01

    Conversion coatings on Ti-6Al-4V alloy was prepared through chemical modification in phytic acid and ammonium fluoride mixed solution. The influences of pH, time and the composition of solution on the microstructure of alloy surface were investigated. Scanning electron microscopy was used to observe the microstructure. The chemical composition of alloy surface before and after modification was investigated by energy dispersive X-ray spectroscopy. The results indicated that a conversion coating could be formed on the Ti-6Al-4V alloy in a mixed solution of phytic acid and ammonium fluoride, the growth and microstructure of the conversion coatings were critically dependent on the pH, time and concentration of phytic acid and ammonium fluoride. In 100 mg/ml phytic acid containing 125 mg/ml ammonium fluoride solution with a pH of 6, a compact conversion coating with the thickness of about 4.7 μm formed after 30 min immersion on Ti-6Al-4V alloy surface. The preliminary evaluation of bioactivity of conversion coating was performed by in vitro cell experiments. The results showed that this chemical modification method is a promising surface modification technique for Ti-6Al-4V alloy inplants.

  20. Ion beam mixing isotopic metal bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Fell, C.J. [Newcastle Univ., NSW (Australia). Dept. of Physics; Kenny, M.J. [CSIRO, Lindfield, NSW (Australia). Div. of Applied Physics

    1993-12-31

    In order to obtain an insight into the mechanisms of ion-solid interactions, bilayer targets can be prepared from two different isotopes. A mixing study SIMS is to be carried out using specially grown monocrystalline bilayers of {sup 58}Ni / {sup 60}Ni. An important aspect of the work is the preparation of high quality single-crystal thin films. The Ni layers will be grown on the (110) surface of pure Ni and verified for crystallinity using Reflection High-Energy Electron Diffraction and Rutherford Backscattering channelling analysis. The Pd bilayers will be grown on a Pd (100) surface. RHEED will be used to confirm the two-dimensional crystallinity of the surface before and after deposition of each layer, and channelling used to confirm bulk film crystallinity. Single crystal substrates are currently being prepared. Analysis of the Ni (110) surface using RHEED at 9 kV shows a streak spacing which corresponds to a lattice spacing of 2.47 {+-} 0.09 Angstroms. 9 refs., 1 fig.

  1. Case study: heavy metals and fluoride contents in the materials of Syrian phosphate industry and in the vicinity of phosphogypsum piles.

    Science.gov (United States)

    Al Attar, L; Al-Oudat, M; Shamali, K; Abdul Ghany, B; Kanakri, S

    2012-01-01

    This study focuses on the determination of heavy metals and fluoride concentrations in the Syrian phosphate industry and in the vicinity of the phosphogypsum (PG) piles. Four sampling campaigns were carried out, in which 86 soil, 139 plant, 30 air particulate, 16 water, 12 PG, 6 phosphate ore (raw and treated) and 3 fertilizer samples were collected. Differential pulse anode stripping voltammetry was used for Pb and Cd determination, atomic absorption spectrometry was used for Zn, Cr and Cu determination, and instrumental neutron activation analysis was used for Se, Ni, As and Hg determination. Fluoride concentration was determined via fluoride ion selective electrode. The data revealed that most of the heavy metals were retained in the fertilizer. Fluoride content in PG was 0.47%. The presence of PG piles showed no impact on the run-off and ground and lake waters in the area. However, fluoride concentration was double the permissible airborne threshold in the sites to the east of the PG piles because of the prevailing wind in the region. Similarly, enhanced concentrations of fluoride were recorded for the eastern soil samples. The content of heavy metals in plants was element- and plant-specific and influenced by the element concentration in soil, the soil texture and the pH. The maximal mean of fluoride was found in the plants species of the eastern sites (699 mg kg(-1)), which mainly related to PG erosion and airborne deposition. Thus, the main impact of the PG piles was to increase the concentration of fluoride in the surrounding area. A national action should be taken to regulate PG piles.

  2. In vitro corrosion of metallic orthodontic brackets: influence of artificial saliva with and without fluorides

    Directory of Open Access Journals (Sweden)

    Mônica Pereira Saporeti

    2012-12-01

    Full Text Available OBJECTIVE: This in vitro study verified the resistance to corrosion of metallic brackets, evaluating the superficial aspects in scanning electron microscopy (SEM and the residual components. METHODS: The sample consisted of 17 sets of brackets of four different metallic alloys: Titanium, Cobalt-Chromium, Stainless steel with low nickel concentration and with titanium nitride coating (NiTi. Twelve sets were submitted to corrosion by immersion in 50 ml of artificial saliva (pH 6.5 and four in saliva (pH 6.5 containing fluoride (2 g/l, all at a temperature of 37 ºC and analyzed after 7, 9 and 11 weeks. One was kept as control set. The analysis consisted in qualitative evaluation of the corrosion by the images obtained on the SEM, in semi-quantitative evaluation of chemical composition of the surface residue by SEM-EDS and the amount of ions released in saliva on evaluation of atomic absorption spectrophotometry. RESULTS: The results showed that the pure titanium brackets and the ones with low nickel concentration were superior regarding resistance to corrosion. The cobalt-chromium alloy showed the greatest corrosion. In the presence of fluoride, it was observed greater variation in all alloys, especially in the ones of NiTi coated steel and the ones of cobalt-chromium. CONCLUSION: Although observed corrosion on the SEM, the spectrophotometry showed low ions release in the artificial saliva, however, the presence of fluoride negatively affected the corrosion resistance.OBJETIVO: este estudo in vitro verificou a resistência à corrosão de braquetes metálicos, avaliando-se os aspectos superficiais em microscopia eletrônica de varredura (MEV e os componentes residuais formados. MÉTODOS: a amostra consistiu de 17 conjuntos de braquetes de quatro diferentes ligas metálicas: titânio, cobalto-cromo, aço inoxidável com baixa concentração de níquel e com cobertura de nitreto de titânio (TiN. Doze conjuntos foram submetidos à corrosão por

  3. Mixed metal oxide crystalline powders and method for the synthesis thereof

    Energy Technology Data Exchange (ETDEWEB)

    Joyce, I.H.; Blonski, R.P.; Maloney, J.J.; Welch, J.J.; Pipoly, R.A.; Byrne, C.J.

    1993-07-20

    A method is described for the solid state synthesis of mixed metal oxide crystalline powders comprising the steps of: preparing a raw material mixture containing at least two different metal cations; adding a template material to said mixture and blending it therewith; initiating formation of a mixed metal oxide by calcination of said mixture and said template material, whereby particles of the mixed metal oxides are formed in powder form; and thereafter recovering said mixed metal oxide particles.

  4. Analysis of heavy metals and fluoride in vegetation by extraction with concentrated mineral acids.

    Science.gov (United States)

    Johnson, M S

    1975-01-01

    A rapid potentiometric method for determining fluoride in vegetation is described. Recovery of flouride by extraction with concentrated mineral acids compares favourably with standard methods of analysis in terms of accuracy and precision. The procedure affords the additional advantage that several citations are also quantitatively extracted and may be determined directly in the acid digest by atomic absorption spectrophotometry.

  5. Evaluation of shielding parameters for heavy metal fluoride based tellurite-rich glasses for gamma ray shielding applications

    Science.gov (United States)

    Sayyed, M. I.; Lakshminarayana, G.; Kityk, I. V.; Mahdi, M. A.

    2017-10-01

    In this work, we have evaluated the γ-ray shielding parameters such as mass attenuation coefficient (μ/ρ), effective atomic number (Zeff), half value layer (HVL), mean free path (MFP) and exposure buildup factors (EBF) for heavy metal fluoride (PbF2) based tellurite-rich glasses. In addition, neutron total macroscopic cross sections (∑R) for these glasses were also calculated. The maximum value for μ/ρ, Zeff and ∑R was found for heavy metal (Bi2O3) oxide introduced glass. The results of the selected glasses have been compared, in terms of MFP with different glass systems. The shielding effectiveness of the selected glasses is found comparable or better than of common ones, which indicates that these glasses with suitable oxides could be developed for gamma ray shielding applications.

  6. BaFAlSi and BaFAlGe: First transition metal-free LaOAgS-type fluoride tetrelides

    Energy Technology Data Exchange (ETDEWEB)

    Charkin, Dmitri O., E-mail: charkin@inorg.chem.msu.ru; Plokhikh, Igor V.; Kuznetsov, Alexey N.; Kazakov, Sergey M.

    2015-04-05

    Highlights: • Two first tetrelide fluorides with the LaOAgS structure have been prepared. • They are also the first transition metal-free representatives of the structure type. • Contrary to pnictides, hydride tetrelides are predicted to have different structures. - Abstract: Studies of the LaOAgS-type compounds among alkaline earth – Al (Ga) fluoride tetrelides revealed the existence of two new compounds BaFAlSi and BaFAlGe which are the first representatives of fluoride tetrelides; they also are the first representatives of the structure type not involving transition metals. No compound of the structure type is formed for strontium and gallium. Quantum chemical calculations indicate that only these two compounds are thermodynamically stable; the structure is probably stabilized by ionic interactions in the FeSe-like anionic slabs, which are relatively weak for bonds formed between triels and tetrels that are close in electronegativity.

  7. Understanding Structure, Metal Distribution, and Water Adsorption in Mixed-Metal MOF-74

    Energy Technology Data Exchange (ETDEWEB)

    Howe, Joshua D.; Morelock, Cody R.; Jiao, Yang; Chapman, Karena W.; Walton, Krista S.; Sholl, David S.

    2017-01-30

    We present a joint computational and experimental study of Mg–Ni-MOF-74 and Mg–Cd-MOF-74 to gain insight into the mixing of metals and understand how metal mixing affects the structure of the undercoordinated open-metal sites. Our calcula tions predict that metal mixing is energetically preferred in these materials. Recent experimental work has demonstrated that Mg–Ni-MOF-74 shows a much greater surface area retention in the presence of water than Mg-MOF-74. To probe this effect, we study H2O adsorption in Mg–Ni-MOF-74, finding that the adsorption en ergetics and electronic structure do not change significantly at the metal sites when compared to Mg-MOF-74 and Ni-MOF-74, respectively. We conclude that the in creased stability of Mg–Ni-MOF-74 is a result of a M–O bond length distortion in mixed-metal MOF-74, consistent with recent work on the stability of MOF-74 under water exposure.

  8. 40 CFR 721.10147 - Acrylate derivative of alkoxysilylalkane ester and mixed metal oxides (generic).

    Science.gov (United States)

    2010-07-01

    ... alkoxysilylalkane ester and mixed metal oxides (generic). 721.10147 Section 721.10147 Protection of Environment... alkoxysilylalkane ester and mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to... ester and mixed metal oxides (PMN P-07-198) is subject to reporting under this section for...

  9. 40 CFR 721.5315 - Nickel, cobalt mixed metal oxide (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Nickel, cobalt mixed metal oxide... Specific Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance... nickel, cobalt mixed metal oxide. (PMN P-02-90) is subject to reporting under this section for the...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-01

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

  11. Fluorescent molecule incorporated metal-organic framework for fluoride sensing in aqueous solution

    Science.gov (United States)

    Zhao, Xudong; Wang, Yuanyang; Hao, Xiuli; Liu, Wen

    2017-04-01

    In this work, the fluorescent molecule (fluorescein sodium, FS) was successfully incorporated in the zirconium-based MOF (UiO-66) via in-situ synthesis method, which can be confirmed by FTIR spectra and fluorescence microscopic images. Based on this in-situ synthesis strategy, FS molecule can be immobilized tightly in the framework. Furthermore, the resulting FS@UiO-66 demonstrates to be a highly selective, real-time and naked-eye chemical sensor for fluoride in aqueous solution, which is mainly due to the release of FS molecule from FS@UiO-66 into the aqueous solution. Meanwhile, to the best of our knowledge, such Zr-MOF-based fluoride sensor is very rare so far. These results provide a promising approach to rationally design novel MOF-based fluorescent sensor for the target molecules.

  12. Alkali metal cation complexation and solvent interactions by robust chromium(III) fluoride complexes

    DEFF Research Database (Denmark)

    Birk, T.; Magnussen, M.J.; Piligkos, Stergios

    2010-01-01

    Interaction of robust chromium(III) fluoride complexes with sodium or lithium cations in solution lead to hypsochromic spectral shifts of increasing magnitude along the series: trans-[CrF2(py)(4)](+), mer-[CrF3(terpy)], and fac-[CrF3(Me(3)tacn)]. Crystalline products isolated from solution exhibit...... mu(2)-bridging by the fluoride ligands in a linear fashion between Na+-ions and chromium centres in catena-[Na(H2O)(4)(mu-F)-trans-{CrF(py)(4))](HCO3)(2) and in the dimers [Li(H2O)(n)(mu-F)-trans-{CrF(py)(4))}](2+) (n = 3, 4). The uncharged chromium complexes fac-[CrF3(Me(3)tacn)] and mer-[CrF3(terpy......)] have been synthesized from mer-[CrF3(py)(3)] and shown to precipitate sodium salts from solution, of which 3[CrF3(Me(3-)tacn)]center dot 2Na(Bph(4)).solv and 6[CrF3(terpy)]center dot 4Na(Bph(4)).solv have been crystallographically characterized. In these clusters, the neutral fluoride complexes bring...

  13. Origins of Large Voltage Hysteresis in High-Energy-Density Metal Fluoride Lithium-Ion Battery Conversion Electrodes.

    Science.gov (United States)

    Li, Linsen; Jacobs, Ryan; Gao, Peng; Gan, Liyang; Wang, Feng; Morgan, Dane; Jin, Song

    2016-03-02

    Metal fluorides and oxides can store multiple lithium ions through conversion chemistry to enable high-energy-density lithium-ion batteries. However, their practical applications have been hindered by an unusually large voltage hysteresis between charge and discharge voltage profiles and the consequent low-energy efficiency (hysteresis are rarely studied and poorly understood. Here we employ in situ X-ray absorption spectroscopy, transmission electron microscopy, density functional theory calculations, and galvanostatic intermittent titration technique to first correlate the voltage profile of iron fluoride (FeF3), a representative conversion electrode material, with evolution and spatial distribution of intermediate phases in the electrode. The results reveal that, contrary to conventional belief, the phase evolution in the electrode is symmetrical during discharge and charge. However, the spatial evolution of the electrochemically active phases, which is controlled by reaction kinetics, is different. We further propose that the voltage hysteresis in the FeF3 electrode is kinetic in nature. It is the result of ohmic voltage drop, reaction overpotential, and different spatial distributions of electrochemically active phases (i.e., compositional inhomogeneity). Therefore, the large hysteresis can be expected to be mitigated by rational design and optimization of material microstructure and electrode architecture to improve the energy efficiency of lithium-ion batteries based on conversion chemistry.

  14. Influence of Fluoride Content of Artificial Saliva on Metal Release from 17-4 PH Stainless Steel Foam for Dental Implant Applications

    Institute of Scientific and Technical Information of China (English)

    Ilven Mutlu; Enver Oktay

    2013-01-01

    Highly porous 17-4 PH stainless steel foam for implant applications was produced by space holder technique.Metal release and weight loss from 17-4 PH stainless steel foams were investigated in fluoride added artificial saliva environment by static immersion test.An inductively coupled plasma-mass spectrometer was employed to measure the concentrations of various metal ions.Effects of fluoride content of artificial saliva on metal release and weight loss from the steel foams were investigated.Effects of immersion time,pH value and process parameters on the weight loss and metal release were determined.Pore morphology,pore size and mechanical properties of the 17-4 PH stainless steel foams were also characterized.

  15. Removal of phosphorus, fluoride and metals from a gypsum mining leachate using steel slag filters.

    Science.gov (United States)

    Claveau-Mallet, Dominique; Wallace, Scott; Comeau, Yves

    2013-03-15

    The objective of this work was to evaluate the capacity of steel slag filters to treat a gypsum mining leachate containing 11-107 mg P/L ortho-phosphates, 9-37 mg/L fluoride, 0.24-0.83 mg/L manganese, 0.20-3.3 zinc and 1.7-8.2 mg/L aluminum. Column tests fed with reconstituted leachates were conducted for 145-222 days and sampled twice a week. Two types of electric arc furnace (EAF) slags and three filter sequences were tested. The voids hydraulic retention time (HRT(v)) of columns ranged between 4.3 and 19.2 h. Precipitates of contaminants present in columns were sampled and analyzed with X-ray diffraction at the end of tests. The best removal efficiencies over a period of 179 days were obtained with sequential filters that were composed of Fort Smith EAF slag operated at a total HRT(v) of 34 h which removed 99.9% of phosphorus, 85.3% of fluoride, 98.0% of manganese and 99.3% of zinc. Mean concentration at this system's effluent was 0.04 mg P/L ortho-phosphates, 4 mg/L fluoride, 0.02 mg/L manganese, 0.02 zinc and 0.5 mg/L aluminum. Thus, slag filters are promising passive and economical systems for the remediation of mining effluents. Phosphorus was removed by the formation of apatite (hydroxyapatite, Ca(5)(PO(4))(3)OH or fluoroapatite, Ca(5)(PO(4))(3)F) as confirmed by visual and X-ray diffraction analyses. The growth rate of apatite was favored by a high phosphorus concentration. Calcite crystals were present in columns and appeared to be competing for calcium and volume needed for apatite formation. The calcite crystal growth rate was higher than that of apatite crystals. Fluoride was removed by precipitation of fluoroapatite and its removal was favored by a high ratio of phosphorus to fluoride in the wastewater.

  16. Surface functionalization of metal organic frameworks for mixed matrix membranes

    Energy Technology Data Exchange (ETDEWEB)

    Albenze, Erik; Lartey, Michael; Li, Tao; Luebke, David R.; Nulwala, Hunaid B.; Rosi, Nathaniel L.; Venna, Surendar R.

    2017-03-21

    Mixed Matrix Membrane (MMM) are composite membranes for gas separation and comprising a quantity of inorganic filler particles, in particular metal organic framework (MOF), dispersed throughout a polymer matrix comprising one or more polymers. This disclosure is directed to MOF functionalized through addition of a pendant functional group to the MOF, in order to improve interaction with a surrounding polymer matrix in a MMM. The improved interaction aids in avoiding defects in the MMM due to incompatible interfaces between the polymer matrix and the MOF particle, in turn increasing the mechanical and gas separation properties of the MMM. The disclosure is also directed to a MMM incorporating the surface functionalized MOF.

  17. Bi–Mn mixed metal organic oxide: A novel 3d-6p mixed metal coordination network

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Fa-Nian, E-mail: fshi@ua.pt [School of Science, Shenyang University of Technology, 110870 Shenyang (China); Department of Chemistry, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Rosa Silva, Ana [Department of Chemistry, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Bian, Liang [Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011, Xinjiang (China)

    2015-05-15

    A new terminology of metal organic oxide (MOO) was given a definition as a type of coordination polymers which possess the feature of inorganic connectivity between metals and the direct bonded atoms and show 1D, 2D or 3D inorganic sub-networks. One such compound was shown as an example. A 3d-6p (Mn–Bi. Named MOOMnBi) mixed metals coordination network has been synthesized via hydrothermal method. The new compound with the molecular formula of [MnBi{sub 2}O(1,3,5-BTC){sub 2}]{sub n} (1,3,5-BTC stands for benzene-1,3,5-tricarboxylate) was characterized via single crystal X-ray diffraction technique that revealed a very interesting 3-dimensional (3D) framework with Bi{sub 4}O{sub 2}(COO){sub 12} clusters which are further connected to Mn(COO){sub 6} fragments into a 2D MOO. The topology study indicates an unprecedented topological type with the net point group of (4{sup 13}.6{sup 2})(4{sup 13}.6{sup 8})(4{sup 16}.6{sup 5})(4{sup 18}.6{sup 10})(4{sup 22}.6{sup 14})(4{sup 3}) corresponding to 3,6,7,7,8,9-c hexa-nodal net. MOOMnBi shows catalytic activity in the synthesis of (E)-α,β-unsaturated ketones. - Graphical abstract: This metal organic framework (MOF) is the essence of a 2D metal organic oxide (MOO). - Highlights: • New concept of metal organic oxide (MOO) was defined and made difference from metal organic framework. • New MOO of MOOMnBi was synthesized by hydrothermal method. • Crystal structure of MOOMnBi was determined by single crystal X-ray analysis. • The catalytic activity of MOOMnBi was studied showing reusable after 2 cycles.

  18. Spin-mixing conductances of metallic and half-metallic magnetic layers.

    Science.gov (United States)

    Turek, I; Carva, K

    2007-09-12

    The spin-mixing conductance of a thin ferromagnetic layer attached epitaxially to two semi-infinite non-magnetic metallic leads is formulated in terms of non-equilibrium Green's functions. The spin-mixing conductance is obtained as a response of the spin torque acting on the ferromagnet with respect to the spin accumulation in one of the leads, while the spin torque is defined as a time derivative of the spin magnetic moment. The equivalence of the derived formula with a previous expression of the Landauer-Büttiker scattering theory is sketched and an implementation within the ab initio tight-binding linear muffin-tin orbital method is briefly described. Applications are made for metallic Co- and Ni-based slabs embedded between Cu(111) leads and for half-metallic Co(2)MnSi films sandwiched by Cr(001) leads. The calculated results throw serious doubts on the general validity of two features: fast convergence of the spin-mixing conductance with increasing thickness of the magnetic layer and negligible values of the imaginary part of the spin-mixing conductance as compared to the real part.

  19. A new adsorbent of a Ce ion-implanted metal-organic framework (MIL-96) with high-efficiency Ce utilization for removing fluoride from water.

    Science.gov (United States)

    Yang, Xuan; Deng, Shuangshuang; Peng, Fumin; Luo, Tao

    2017-02-14

    A novel Ce(iii) ion-implanted aluminum-trimesic metal-organic framework (Ce-MIL-96) was synthesized for the first time via alcohol-solvent incipient wetness impregnation. Compared to previously reported Ce-contained adsorbents, the fluoride adsorption performance of the new ion-implanted metal-organic framework demonstrated much higher adsorption capacity and more efficient regeneration of Ce. In a wide pH range of 3 to 10, Ce-MIL-96 maintained constant adsorption performance for fluoride, and the residual Ce and Al in the treated solution were below the safe limits in drinking water. The maximum adsorption capacity of Ce-MIL-96 was 38.65 mg g(-1) at 298 K. Excluding the contribution of MIL-96, the maximum adsorption capacity of Ce ions was 269.75 mg g(-1), which demonstrated that the service efficiency of cerium in Ce-MIL-96 is about 6 times that in Ce2O3, nearly 10 times that in Ce-mZrp, and double that in Mn-Ce oxides. There was no significant influence on fluoride removal by Ce-MIL-96 due to the presence of chloride, nitrate, sulfate, bicarbonate or phosphate. Moreover, the adsorption capacity of Ce-MIL-96 remained at more than 70% after nine cycles of adsorption-desorption. Due to this excellent adsorption performance and its regeneration properties, Ce-MIL-96 is a promising adsorbent for the removal of fluoride from groundwater.

  20. Does the mixing length parameter depend on metallicity?

    CERN Document Server

    Palmieri, R; Saviane, I; Girardi, L; Castellani, V; Palmieri, Rossella; Piotto, Giampaolo; Saviane, Ivo; Girardi, Leo; Castellani, Vittorio

    2002-01-01

    This paper is a further step in the investigation of the morphology of the color-magnitude diagram of Galactic globular clusters, and the fine-tuning of theoretical models, made possible by the recent observational efforts to build homogeneous photometric databases. In particular, we examine here the calibration of the morphological parameter W(HB) vs. metallicity, originally proposed by Brocato et al. (1998), which essentially measures the color position of the red-giant branch. We show that the parameter can be used to have a first-order estimate of the cluster metallicity, since the dispersion around the mean trend with [Fe/H] is compatible with the measurement errors. The tight W(HB)-[Fe/H] relation is then used to show that variations in helium content or age do not affect the parameter, whereas it is strongly influenced by the mixing-length parameter alpha (as expected). This fact allows us, for the first time, to state that there is no trend of alpha with the metal content of a cluster. A thorough exam...

  1. Mixed-metal chalcogenide tetrahedral clusters with an exo-polyhedral metal fragment.

    Science.gov (United States)

    Yuvaraj, K; Roy, Dipak Kumar; Anju, V P; Mondal, Bijnaneswar; Varghese, Babu; Ghosh, Sundargopal

    2014-12-07

    The reaction of metal carbonyl compounds with group 6 and 8 metallaboranes led us to report the synthesis and structural characterization of several novel mixed-metal chalcogenide tetrahedral clusters. Thermolysis of arachno-[(Cp*RuCO)2B2H6], 1, and [Os3(CO)12] in the presence of 2-methylthiophene yielded [Cp*Ru(CO)2(μ-H){Os3(CO)9}S], 3, and [Cp*Ru(μ-H){Os3(CO)11}], 4. In a similar fashion, the reaction of [(Cp*Mo)2B5H9], 2, with [Ru3(CO)12] and 2-methylthiophene yielded [Cp*Ru(CO)2(μ-H){Ru3(CO)9}S], 5, and conjuncto-[(Cp*Mo)2B5H8(μ-H){Ru3(CO)9}S], 6. Both compounds 3 and 5 can be described as 50-cve (cluster valence electron) mixed-metal chalcogenide clusters, in which a sulfur atom replaces one of the vertices of the tetrahedral core. Compounds 3 and 5 possess a [M3S] tetrahedral core, in which the sulfur is attached to an exo-metal fragment, unique in the [M3S] metal chalcogenide tetrahedral arrangements. All the compounds have been characterized by mass spectrometry, IR, and (1)H, (11)B and (13)C NMR spectroscopy in solution, and the solid state structures were unequivocally established by crystallographic analysis of compounds 3, 5 and 6.

  2. Reactivity of first-row transition metal monocations (Sc+, Ti+, V+, Zn+) with methyl fluoride: a computational study.

    Science.gov (United States)

    Redondo, Pilar; Varela-Álvarez, Adrián; Rayón, Víctor Manuel; Largo, Antonio; Sordo, José Ángel; Barrientos, Carmen

    2013-04-11

    The gas-phase reactivity of methyl fluoride with selected first-row transition metal monocations (Sc(+), Ti(+), V(+), and Zn(+)) has been theoretically investigated. Our thermochemical and kinetics study shows that early transition-metal cations exhibit a much more active chemistry than the latest transition metal monocation Zn(+). The strong C-F bond in methyl fluorine can be activated by scandium, titanium, and vanadium monocations yielding the metal fluorine cation, MF(+). However, the rate efficiencies vary dramatically along the period 0.73 (Sc), 0.91 (Ti), and 0.028 (V) in agreement with the experimental observation. The kinetics results show the relative importance of the entrance and exit channels, apart from the "inner" bottleneck, to control the global rate constant of these reactions. At the mPW1K/QZVPP level our computed kglobal (at 295 K), 1.99 × 10(-9) cm(3) molecule(-1) s(-1) (Sc(+)), 1.29 × 10(-9) cm(3) molecule(-1) s(-1) (Ti(+)), and 3.46 × 10(-10) cm(3) molecule(-1) s(-1) (V(+)) are in good agreement with the experimental data at the same temperature. For the reaction of Zn(+) and CH3F our predicted value for kouter, at 295 K, 3.79 × 10(-9) cm(3) molecule(-1) s(-1), is in accordance with the capture rate constant. Our study suggests that consideration of the lowest excited states for Ti(+) and V(+) is mandatory to reach agreement between calculations and experimental measurements.

  3. Flexible Electronics Powered by Mixed Metal Oxide Thin Film Transistors

    Science.gov (United States)

    Marrs, Michael

    A low temperature amorphous oxide thin film transistor (TFT) and amorphous silicon PIN diode backplane technology for large area flexible digital x-ray detectors has been developed to create 7.9-in. diagonal backplanes. The critical steps in the evolution of the backplane process include the qualification and optimization of the low temperature (200 °C) metal oxide TFT and a-Si PIN photodiode process, the stability of the devices under forward and reverse bias stress, the transfer of the process to flexible plastic substrates, and the fabrication and assembly of the flexible detectors. Mixed oxide semiconductor TFTs on flexible plastic substrates suffer from performance and stability issues related to the maximum processing temperature limitation of the polymer. A novel device architecture based upon a dual active layer improves both the performance and stability. Devices are directly fabricated below 200 ºC on a polyethylene naphthalate (PEN) substrate using mixed metal oxides of either zinc indium oxide (ZIO) or indium gallium zinc oxide (IGZO) as the active semiconductor. The dual active layer architecture allows for adjustment to the saturation mobility and threshold voltage stability without the requirement of high temperature annealing, which is not compatible with flexible plastic substrates like PEN. The device performance and stability is strongly dependent upon the composition of the mixed metal oxide; this dependency provides a simple route to improving the threshold voltage stability and drive performance. By switching from a single to a dual active layer, the saturation mobility increases from 1.2 cm2/V-s to 18.0 cm2/V-s, while the rate of the threshold voltage shift decreases by an order of magnitude. This approach could assist in enabling the production of devices on flexible substrates using amorphous oxide semiconductors. Low temperature (200°C) processed amorphous silicon photodiodes were developed successfully by balancing the tradeoffs

  4. Large resistivity modulation in mixed-phase metallic systems

    Science.gov (United States)

    Lee, Yeonbae; Liu, Zhiqi; Heron, John; Clarkson, James; Hong, Jeongmin; Ko, Changhyun; Biegalski, Michael; Aschauer, Ulrich; Hsu, Shang-Lin; Nowakowski, Mark; Wu, Junqiao; Christen, Hans; Salahuddin, Sayeef; Bokor, Jeffrey; Spaldin, Nicola; Schlom, Darrell; Ramesh, Ramamoorthy

    2015-03-01

    We have investigated the effect of an electric field to FeRh/PMN-PT heterostructures and report 8% change in the electrical resistivity of FeRh films. Such a ``giant'' electroresistance (GER) response is striking in metallic systems, in which external electric fields are screened and thus only weakly influence the carrier concentrations and mobilities. We show that our FeRh films comprise coexisting ferromagnetic and antiferromagnetic phases with different resistivities, and the origin of the GER effect is the strain-mediated change in their relative proportions. The observed behavior is reminiscent of colossal magnetoresistance in perovskite manganites, and illustrates the role of mixed-phase coexistence in achieving large changes in physical properties with low-energy external perturbation.

  5. Selective propene oxidation on mixed metal oxide catalysts

    CERN Document Server

    James, D W

    2002-01-01

    Selective catalytic oxidation processes represent a large segment of the modern chemical industry and a major application of these is the selective partial oxidation of propene to produce acrolein. Mixed metal oxide catalysts are particularly effective in promoting this reaction, and the two primary candidates for the industrial process are based on iron antimonate and bismuth molybdate. Some debate exists in the literature regarding the operation of these materials and the roles of their catalytic components. In particular, iron antimonate catalysts containing excess antimony are known to be highly selective towards acrolein, and a variety of proposals for the enhanced selectivity of such materials have been given. The aim of this work was to provide a direct comparison between the behaviour of bismuth molybdate and iron antimonate catalysts, with additional emphasis being placed on the component single oxide phases of the latter. Studies were also extended to other antimonate-based catalysts, including coba...

  6. Novel polyvinylidene fluoride nanofiltration membrane blended with functionalized halloysite nanotubes for dye and heavy metal ions removal

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Guangyong [State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); Oil & Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); He, Yi, E-mail: heyi@swpu.edu.cn [State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); Oil & Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); Zhan, Yingqing; Zhang, Lei; Pan, Yang; Zhang, Chunli; Yu, Zongxue [State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500 (China)

    2016-11-05

    Highlights: • A novel PVDF nanofiltration membrane was prepared by incorporation of A-HNTs. • HNTs dispersed well in membrane matrix after APTES modification. • The membrane exhibited excellent hydrophilicity and antifouling properties. • A high dye and heavy metal ions removal was realized by membrane separation. - Abstract: Membrane separation is an effective method for the removal of hazardous materials from wastewater. Halloysite nanotubes (HNTs) were functionalized with 3-aminopropyltriethoxysilane (APTES), and novel polyvinylidene fluoride (PVDF) nanofiltration membranes were prepared by blending with various concentrations of APTES grafted HNTs (A-HNTs). The morphology structure of the membranes were characterized by scanning electron microscope (SEM) and atomic force microscopy (AFM). The contact angle (CA), pure water flux (PWF) and antifouling capacity of membranes were investigated in detail. In addition, the separation performance of membranes were reflected by the removal of dye and heavy metal ions in simulated wastewater. The results revealed that the hydrophilicity of A-HNTs blended PVDF membrane (A-HNTs@PVDF) was enhanced significantly. Owing to the electrostatic interaction between membrane surface and dye molecules, the dye rejection ratio of 3% A-HNTs@PVDF membrane reached 94.9%. The heavy metal ions rejection ratio and adsorption capacity of membrane were also improved with the addition of A-HNTs. More importantly, A-HNTs@PVDF membrane exhibited excellent rejection stability and reuse performances after several times fouling and washing tests. It can be expected that the present work will provide insight into a new method for membrane modification in the field of wastewater treatment.

  7. The physical and chemical properties of nanostructured mixed-metal catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Li [Texas A & M Univ., College Station, TX (United States); Goodman, David Wayne [Texas A & M Univ., College Station, TX (United States)

    2016-04-21

    The main targets of this study has been to synthesize well-defined nanoclusters of Ni, Co, Pt, Rh and Pd as well as mixed-metal nanoclusters on ultrathin oxide surfaces and to characterize their detailed morphology using scanning probe techniques. The focus of the research is an understanding of the effects of metal-substrate interactions and overall composition on the structure/stability of single metal and mixed-metal nanoclusters and their catalytic activity.

  8. Agglomerated nanoparticles of hydrous Ce(IV) + Zr(IV) mixed oxide: Preparation, characterization and physicochemical aspects on fluoride adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Abir; Chakrabarti, Sharadindra; Biswas, Krishna; Ghosh, Uday Chand, E-mail: ucghosh@yahoo.co.in

    2014-07-01

    Hydrous Ce(IV)–Zr(IV) oxide (Ce/Zr ~ 1:1, mol/mol) (HCZMO) prepared by simple chemical precipitation was nanoparticles (60–70 nm) agglomerate with irregular surface morphology. The BET surface area, pore volume and pHzpc were estimated to be 185.04 m² g⁻¹, 0.1219 cm³ g⁻¹ and 5.8 (±0.2), respectively. Investigation of fluoride adsorption over HCZMO from its aqueous phase at an optimized pH ~ 6.0 showed that the adsorption kinetics and equilibrium data described, respectively, the pseudo-second order equation (R² = 0.98–0.99) and the Langmuir isotherm (R² > 0.99) very well. Values of the computed Arrhenius activation energy, Ea (1.16 kJ mol⁻¹), Langmuir monolayer capacity, θ (19.5 mg g⁻¹), D–R adsorption energy, ED–R (15.05 kJ mol⁻¹) and isosteric heat of reaction, ΔHr (0.518 kJ mol⁻¹) suggested that the fluoride has high affinity for homogeneous HCZMO surface for adsorption. Evidences appeared from the equal distribution co-efficient values and too well Langmuir isotherm fit. The fluoride adsorption reactions at 298–313 K with HCZMO were spontaneous (ΔG⁰ = negative) despite endothermic nature (ΔH⁰, kJ mol⁻¹ = +3.53, +4.04), owing to the increase of entropy (ΔS⁰, J mol⁻¹ K⁻¹ = +12.4, 13.8). More than 95% fluoride was released from F⁻-HCZMO (24.8 mg F⁻ g⁻¹) by 1.0 M NaOH, confirming the ion-exchange adsorption mechanism inclining to chemisorption. 1 g HCZMO per liter of a groundwater (F⁻: 4.40 mg L⁻¹) can reduce fluoride level below 1.5 mg L⁻¹ in batch treatment.

  9. FLUORIDE TOXICITY – A HARSH REALITY

    Directory of Open Access Journals (Sweden)

    Bandlapalli Pavani

    2011-04-01

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

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

    Science.gov (United States)

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

    2014-08-01

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

  11. Non ideal detonation of emulsion explosives mixed with metal particles

    Science.gov (United States)

    Mendes, Ricardo; Ribeiro, José B.; Plaksin, I.; Campos, Jose

    2012-03-01

    The detonation of ammonium nitrate based compositions like emulsion explosives mixed with metal particles was experimentally investigated. Aluminum powder with a mean particle size of 6 μm was used, and the mass concentration of aluminum on the explosive charge ranged from 0 to 30% wt. The values of the detonation velocity, the pressure attenuation - P(x) - of the shock front amplitude in a standard PMMA monitor and manganin gauges pressure-time histories are shown as a function of the explosive charge porosity and specific mass. All these parameters except the pressuretimes histories have been evaluated using the multi-fiber optical probe (MFOP) method which is based on the use of an optical fiber strip, with 64 independent optical fibers. The MFOP allows a quasicontinuous evaluation of the detonation wave run propagation and the assessment of spatial resolved measurements of the shock wave induced in the PMMA barrier. Results of that characterization process are presented and discussed for aluminized and non-aluminized emulsion explosives. The experimental results have shown that the detonation velocity decreases monotonically with the increase of aluminum content. Nevertheless the peak of detonation pressure profiles presents a non-monotonic behavior increasing its value up to an Al content of 20% wt, after which it starts to decrease.

  12. Non ideal detonation of emulsion explosives mixed with metal particles

    Science.gov (United States)

    Mendes, R.; Ribeiro, J.; Plaksin, I.; Campos, J.

    2011-06-01

    The detonation of ammonium nitrate based compositions like emulsion explosives (EX) mixed with metal particles has been investigated experimentally. Aluminium powder with a mean particle size of 10 μm was used, and the mass concentration of aluminum on the explosive charge was ranged from 0 to 30%. The values of the detonation velocity, the pressure attenuation - P(x) - of detonation front amplitude in a standard PMMA monitor and manganin gauges pressure-time histories are shown as a function of the explosive charge porosity and specific mass. All these parameters except the pressure-times histories have been evaluated using the multi fiber optical probe (MFOP) method which is based on the use of an optical fiber strip, with 64 independent optical fibers. The MFOP allow a quasi continuous evaluation of the detonation wave run propagation and the assessment to spatial resolved measurements of the shock wave induced in the PMMA barrier which in turns allows a detailed characterization of the detonation reaction zone structure. Results of that characterization process are presented and discussed for aluminized and non aluminized EX. Moreover, the effect of the mass concentration of the sensitizing agent (hollow glass micro-balloons) on the non monotonic detonation velocity variation, for EX, will be discussed.

  13. Mechanical stimulated reaction of metal/polymer mixed powders; Kinzoku/kobunshi kongo funmatsu no kikaiteki reiki hanno

    Energy Technology Data Exchange (ETDEWEB)

    Tobita, M.; Sakakibara, A.; Takemoto, Y. [Okayama University, Okayama (Japan). Faculty of Engineering; Iwabu, H. [Kurare Co. Ltd., Osaka (Japan)

    1999-12-15

    Mechanical grinding (MG) with mechanically stimulated reaction was performed on metal/polymer mixed powders. The starting materials used in this study were the metals of Mg, Ti and Mg{sub 2}Ni powders, arid polymer of PTFE, PVC and PE powders. The MG process was investigated using XRD, IR, SEM and TEM. According to XRD results, magnesium fluoride (MgF{sub 2}, TiF{sub 2}) and chloride (MgCl{sub 2}) were detected from MG products of the Mg/PTFE, Ti/PTFE and Mg/PVC blending systems, respectively. Explosive reaction was found during MG of both Mg/PTFE and Ti/PTFE. It was also confirmed by XRD results that the production of MgF{sub 2} had already been formed just before the explosive reaction in Mg/PTFE system. It was found from IR analysis that C-C single bond in the polymers, not only both in PTFE and PVC but also in PE, changed to double bond C=C. Hydrogen produced due to decomposition of PE on blending Mg{sub 2}Ni/PE was absorbed into C-Mg{sub 2}Ni-H as amorphous solutes. These mechanically stimulated reaction was powerful method for decomposition of engineering plastics. (author)

  14. Capillary electrophoresis with contactless conductivity detection for the quantification of fluoride in lithium ion battery electrolytes and in ionic liquids-A comparison to the results gained with a fluoride ion-selective electrode.

    Science.gov (United States)

    Pyschik, Marcelina; Klein-Hitpaß, Marcel; Girod, Sabrina; Winter, Martin; Nowak, Sascha

    2017-02-01

    In this study, an optimized method using capillary electrophoresis (CE) with a direct contactless conductivity detector (C(4) D) for a new application field is presented for the quantification of fluoride in common used lithium ion battery (LIB) electrolyte using LiPF6 in organic carbonate solvents and in ionic liquids (ILs) after contacted to Li metal. The method development for finding the right buffer and the suitable CE conditions for the quantification of fluoride was investigated. The results of the concentration of fluoride in different LIB electrolyte samples were compared to the results from the ion-selective electrode (ISE). The relative standard deviations (RSDs) and recovery rates for fluoride were obtained with a very high accuracy in both methods. The results of the fluoride concentration in the LIB electrolytes were in very good agreement for both methods. In addition, the limit of detection (LOD) and limit of quantification (LOQ) values were determined for the CE method. The CE method has been applied also for the quantification of fluoride in ILs. In the fresh IL sample, the concentration of fluoride was under the LOD. Another sample of the IL mixed with Li metal has been investigated as well. It was possible to quantify the fluoride concentration in this sample.

  15. WHO water quality standards Vs Synergic effect(s) of fluoride, heavy metals and hardness in drinking water on kidney tissues

    Science.gov (United States)

    Wasana, Hewa M. S.; Perera, Gamage D. R. K.; Gunawardena, Panduka De S.; Fernando, Palika S.; Bandara, Jayasundera

    2017-01-01

    Despite WHO standards, waterborne diseases among the human being are rising alarmingly. It is known that the prolong exposure to contaminated water has major impact on public health. The effect of chemical contaminations in drinking water on human being is found to be chronic rather than acute and hence can be defined “consumption of contaminated drinking water could be a silent killer”. As the WHO recommended water quality standards are only for individual element and synergic effects of trace metals and anions have not been considered, investigation of synergic effects of trace metals and anions and their effect on human being is of prime important research. By an animal trial, we investigated the synergic effect(s) of heavy metals, aluminium, arsenic, fluoride and hardness in drinking water on kidney tissues of mice. Our investigation strongly suggests existing of a synergic effect especially among Cd, F and hardness of water which could lead to severe kidney damage in mice, even at WHO maximum recommended levels. Hence, the synergic effect(s) of trace metals, fluoride and hardness present in drinking water should be investigated meticulously when stipulating the water quality at WHO maximum recommended levels. PMID:28195172

  16. WHO water quality standards Vs Synergic effect(s) of fluoride, heavy metals and hardness in drinking water on kidney tissues

    Science.gov (United States)

    Wasana, Hewa M. S.; Perera, Gamage D. R. K.; Gunawardena, Panduka De S.; Fernando, Palika S.; Bandara, Jayasundera

    2017-02-01

    Despite WHO standards, waterborne diseases among the human being are rising alarmingly. It is known that the prolong exposure to contaminated water has major impact on public health. The effect of chemical contaminations in drinking water on human being is found to be chronic rather than acute and hence can be defined “consumption of contaminated drinking water could be a silent killer”. As the WHO recommended water quality standards are only for individual element and synergic effects of trace metals and anions have not been considered, investigation of synergic effects of trace metals and anions and their effect on human being is of prime important research. By an animal trial, we investigated the synergic effect(s) of heavy metals, aluminium, arsenic, fluoride and hardness in drinking water on kidney tissues of mice. Our investigation strongly suggests existing of a synergic effect especially among Cd, F and hardness of water which could lead to severe kidney damage in mice, even at WHO maximum recommended levels. Hence, the synergic effect(s) of trace metals, fluoride and hardness present in drinking water should be investigated meticulously when stipulating the water quality at WHO maximum recommended levels.

  17. WHO water quality standards Vs Synergic effect(s) of fluoride, heavy metals and hardness in drinking water on kidney tissues.

    Science.gov (United States)

    Wasana, Hewa M S; Perera, Gamage D R K; Gunawardena, Panduka De S; Fernando, Palika S; Bandara, Jayasundera

    2017-02-14

    Despite WHO standards, waterborne diseases among the human being are rising alarmingly. It is known that the prolong exposure to contaminated water has major impact on public health. The effect of chemical contaminations in drinking water on human being is found to be chronic rather than acute and hence can be defined "consumption of contaminated drinking water could be a silent killer". As the WHO recommended water quality standards are only for individual element and synergic effects of trace metals and anions have not been considered, investigation of synergic effects of trace metals and anions and their effect on human being is of prime important research. By an animal trial, we investigated the synergic effect(s) of heavy metals, aluminium, arsenic, fluoride and hardness in drinking water on kidney tissues of mice. Our investigation strongly suggests existing of a synergic effect especially among Cd, F and hardness of water which could lead to severe kidney damage in mice, even at WHO maximum recommended levels. Hence, the synergic effect(s) of trace metals, fluoride and hardness present in drinking water should be investigated meticulously when stipulating the water quality at WHO maximum recommended levels.

  18. Dentifrice Fluoride

    Science.gov (United States)

    Rakita, Philip E.

    2004-05-01

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

  19. Transition metal impurities in fluorides: Role of electronic structure of fluorine on spectroscopic properties

    DEFF Research Database (Denmark)

    Trueba, A.; Garcia-Fernandez, P.; García Lastra, Juan Maria

    2011-01-01

    This work examines the relation between optical properties of a MF6q− complex (M=transition–metal cation) and the chemical bonding paying especial attention to the role played by the electronic structure of fluorine. A main goal of the present study is to understand why if the effective Racah...... that the reduction of Racah parameters essentially reflects the global covalency in the bonding. The way of measuring the 2p(F) and 2s(F) admixtures into the mainly 3d(Cr) level through Electron Paramagnetic Resonance data for MF6q− complexes with unpaired σ electrons in the ground state is also explained in some...... detail. At the same time the reasons avoiding its measurement from optical spectra are pointed out as well. The present results stress that the microscopic origin of an optical parameter like 10Dq can certainly be very subtle....

  20. Metathesis synthesis and characterization of complex metal fluoride, KMF3 (M = Mg, Zn, Mn, Ni, Cu and Co) using mechanochemical activation

    Indian Academy of Sciences (India)

    V Manivannan; P Parhi; Jonathan W Kramer

    2008-12-01

    Metathesis synthesis of complex metal fluorides using mechanochemical activation has been reported. The high lattice energy of the byproduct KCl helps the reaction towards product formation in under 20 min. The proposed process, in contrast to the available methods of synthesis, is very rapid, economical and results in products with controlled morphology. The structural, optical and chemical properties of synthesized powders are determined by powder X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, magnetization measurements and diffused reflectance spectra in the UV–VIS range.

  1. Mixed-species biofilms cultured from an oil sand tailings pond can biomineralize metals.

    Science.gov (United States)

    Golby, Susanne; Ceri, Howard; Marques, Lyriam L R; Turner, Raymond J

    2014-07-01

    Here, we used an in vitro biofilm approach to study metal resistance and/or tolerance of mixed-species biofilms grown from an oil sand tailings pond in northern Alberta, Canada. Metals can be inhibitory to microbial hydrocarbon degradation. If microorganisms are exposed to metal concentrations above their resistance levels, metabolic activities and hydrocarbon degradation can be slowed significantly, if not inhibited completely. For this reason, bioremediation strategies may be most effective if metal-resistant microorganisms are used. Viability was measured after exposure to a range of concentrations of ions of Cu, Ag, Pb, Ni, Zn, V, Cr, and Sr. Mixed-species biofilms were found to be extremely metal resistant; up to 20 mg/L of Pb, 16 mg/L of Zn, 1,000 mg/L of Sr, and 3.2 mg/L of Ni. Metal mineralization was observed by visualization with scanning electron microscopy with metal crystals of Cu, Ag, Pb, and Sr exuding from the biofilms. Following metal exposure, the mixed-species biofilms were analyzed by molecular methods and were found to maintain high levels of species complexity. A single species isolated from the community (Rhodococcus erythropolis) was used as a comparison against the mixed-community biofilm and was seen to be much less tolerant to metal stress than the community and did not biomineralize the metals.

  2. Preparation, spectroscopic characterization and antimicrobial activities of mixed metal (Sb and Bi) bridged derivatives with mixed sulfur donor ligands

    Science.gov (United States)

    Joshi, Sapana; Chauhan, H. P. S.; Carpenter, Nitin

    2017-01-01

    This article explores the syntheses of six mixed metal derivatives of antimony(III) and bismuth(III) by the reaction of ethane-1,2-dithiol and metal bis derivatives of dithiocarbamates and/or dithiophosphates ligands in 1:1:1 M stoichiometry. These derivatives have been characterized by physicochemical [elemental analysis (C, H, N, S, Sb and Bi), molecular weight and melting point determinations], spectral [UV-Visible, FTIR, NMR (1H, 13C and 31P)], powder X-ray diffraction studies. These derivatives have nano-ranged crystallite size (8.18-18.04 nm) with monoclinic crystal system. All the synthesized derivatives have two metal centers (Sb and Bi) which elevate the zone of inhibition against four bacterial and two fungal species as compared to single metal species (metal precursors) as well as standard drugs.

  3. Enhanced Antimicrobial Activity Of Antibiotics Mixed With Metal Nanoparticles

    Science.gov (United States)

    Kumar, Sandeep; Kumar, Neeraj; Bhanjana, Gaurav; Thakur, Rajesh; Dilbaghi, Neeraj

    2011-12-01

    Current producers of antimicrobial technology have a long lasting, environmentally safe, non-leaching, water soluble solution that will eventually replace all poisons and heavy metals. The transition metal ions inevitably exist as metal complexes in biological systems by interaction with the numerous molecules possessing groupings capable of complexation or chelation. Nanoparticles of metal oxides offer a wide variety of potential applications in medicine due to the unprecedented advances in nanobiotechnology research. the bacterial action of antibiotics like penicillin, erythryomycin, ampicillin, streptomycin, kanamycin etc. and that of a mixture of antibiotics and metal and metal oxide nanoparticles like zinc oxide, zirconium, silver and gold on microbes was examined by the agar-well-diffusion method, enumeration of colony-forming units (CFU) and turbidimetry.

  4. Thermodynamic properties and mixing thermodynamic parameters of two-phase metallic melts

    Institute of Scientific and Technical Information of China (English)

    Jian Zhang

    2005-01-01

    Based on the calculating model of metallic melts involving eutectic, the calculating equations of mixing thermodynamic parameters for two phase metallic melts have been formulated in the light of those equations of homogeneous solutions. Irrespective as to whether the activity deviation relative to Raoultian behavior is positive or negative, or the deviation is symmetrical or unsymmetrical, the evaluated results not only agree well with experimental values, but also strictly obey the mass action law. This testifies that these equations can authentically reflect the structural reality and mixing thermodynamic characteristics of two-phase metallic melts. The calculating equations of mixing thermodynamic parameters for the model of two phase metallic melts offer two practical criteria (activity and mixing thermodynamic parameters) and one theoretical criterion (the mass action law).

  5. Synthesis and Characterization of Mixed Metal Oxide Nanocomposite Energetic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Gash, A; Pantoya, M; Jr., J S; Zhao, L; Shea, K; Simpson, R; Clapsaddle, B

    2003-11-18

    In the field of composite energetic materials, properties such as ingredient distribution, particle size, and morphology, affect both sensitivity and performance. Since the reaction kinetics of composite energetic materials are typically controlled by the mass transport rates between reactants, one would anticipate new and potentially exceptional performance from energetic nanocomposites. We have developed a new method of making nanostructured energetic materials, specifically explosives, propellants, and pyrotechnics, using sol-gel chemistry. A novel sol-gel approach has proven successful in preparing metal oxide/silicon oxide nanocomposites in which the metal oxide is the major component. Two of the metal oxides are tungsten trioxide and iron(III) oxide, both of which are of interest in the field of energetic materials. Furthermore, due to the large availability of organically functionalized silanes, the silicon oxide phase can be used as a unique way of introducing organic additives into the bulk metal oxide materials. As a result, the desired organic functionality is well dispersed throughout the composite material on the nanoscale. By introducing a fuel metal into the metal oxide/silicon oxide matrix, energetic materials based on thermite reactions can be fabricated. The resulting nanoscale distribution of all the ingredients displays energetic properties not seen in its microscale counterparts due to the expected increase of mass transport rates between the reactants. The synthesis and characterization of these metal oxide/silicon oxide nanocomposites and their performance as energetic materials will be discussed.

  6. Environmental fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Marier, J.R.; Rose, D.

    1971-01-01

    Modern-day man is probably exposed to more environmental fluoride than was heretofore suspected, and consideration must be given to the total ingestion from various sources as well as the types of fluoride present in air, foods, beverages, and other commodities. An effort should also be made to study the symptomology of chronic fluorine intoxication, especially the early non-skeletal manifestations of arthritic-like symptoms that may be complicated by metabolic and/or nutritional inadequacies. Finally, it must be emphasized again that dental fluorosis (i.e. mottling) will only be seen in subjects who have been exposed to fluoride during the time when the enamel of the permanent teeth is being formed, and its absence cannot be assumed to indicate freedom from other fluoride-induced effects including effects of organofluorides and their metabolites. 168 references.

  7. Formation of nuclei during precipitation in metallic mixed crystals

    Science.gov (United States)

    Becker, R.

    1988-01-01

    Assuming that the energy of a mixed crystal can be calculated by simple addition of neighboring bonds, the nuclear formation energy is calculated for precipation in a super-saturated binary mixed crystal. From this can be determined the frequency of the formation of nuclei. From the calculation of a numerical example we can obtain, for the degree of sub-cooling at which the frequency of the formation of nuclei reaches its maximum, satisfactory agreement with available measurements of the rate of precipitation.

  8. Heavy metal-immobilizing organoclay facilitates polycyclic aromatic hydrocarbon biodegradation in mixed-contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, Bhabananda; Sarkar, Binoy [Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes Campus, SA 5095 (Australia); Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, P.O. Box 486, Salisbury, SA 5106 (Australia); Mandal, Asit [Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes Campus, SA 5095 (Australia); Division of Soil Biology, Indian Institute of Soil Science, Bhopal, Madhya Pradesh (India); Naidu, Ravi [Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes Campus, SA 5095 (Australia); Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, P.O. Box 486, Salisbury, SA 5106 (Australia)

    2015-11-15

    Highlights: • A novel metal-immobilizing organoclay (MIOC) synthesized and characterized. • MIOC immobilizes toxic metals and reduces metal bioavailability. • It enhances PAH-bioavailability to soil bacteria. • It improves microbial growth and activities in mixed-contaminated soils. • MIOC facilitates PAH-biodegradation in metal co-contaminated soils. - Abstract: Soils contaminated with a mixture of heavy metals and polycyclic aromatic hydrocarbons (PAHs) pose toxic metal stress to native PAH-degrading microorganisms. Adsorbents such as clay and modified clay minerals can bind the metal and reduce its toxicity to microorganisms. However, in a mixed-contaminated soil, an adsorption process more specific to the metals without affecting the bioavailability of PAHs is desired for effective degradation. Furthermore, the adsorbent should enhance the viability of PAH-degrading microorganisms. A metal-immobilizing organoclay (Arquad{sup ®} 2HT-75-bentonite treated with palmitic acid) (MIOC) able to reduce metal (cadmium (Cd)) toxicity and enhance PAH (phenanthrene) biodegradation was developed and characterized in this study. The MIOC differed considerably from the parent clay in terms of its ability to reduce metal toxicity (MIOC > unmodified bentonite > Arquad–bentonite). The MIOC variably increased the microbial count (10–43%) as well as activities (respiration 3–44%; enzymatic activities up to 68%), and simultaneously maintained phenanthrene in bioavailable form in a Cd-phenanthrene mixed-contaminated soil over a 21-day incubation period. This study may lead to a new MIOC-assisted bioremediation technique for PAHs in mixed-contaminated soils.

  9. Other Fluoride Products

    Science.gov (United States)

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

  10. Bottled Water and Fluoride

    Science.gov (United States)

    ... bottled water and fluoride. Does bottled water contain fluoride? Bottled water products may contain fluoride, depending on ... How can I find out the level of fluoride in bottled water? The FDA does not require ...

  11. Other Fluoride Products

    Science.gov (United States)

    ... Water Fluoridation Journal Articles for Community Water Fluoridation Other Fluoride Products Recommend on Facebook Tweet Share Compartir ... Use the information listed below to compare the other fluoride products that may lower the risk for ...

  12. Synthesis and Characterization of Mixed Metal Oxide Nanocomposite Energetic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Clapsaddle, B; Gash, A; Plantier, K; Pantoya, M; Jr., J S; Simpson, R

    2004-04-27

    In the field of composite energetic materials, properties such as ingredient distribution, particle size, and morphology affect both sensitivity and performance. Since the reaction kinetics of composite energetic materials are typically controlled by the mass transport rates between reactants, one would anticipate new and potentially exceptional performance from energetic nanocomposites. We have developed a new method of making nanostructured energetic materials, specifically explosives, propellants, and pyrotechnics, using sol-gel chemistry. A novel sol-gel approach has proven successful in preparing metal oxide/silicon oxide nanocomposites in which the metal oxide is the major component. By introducing a fuel metal, such as aluminum, into the metal oxide/silicon oxide matrix, energetic materials based on thermite reactions can be fabricated. Two of the metal oxides are tungsten trioxide and iron(III) oxide, both of which are of interest in the field of energetic materials. In addition, due to the large availability of organically functionalized silanes, the silicon oxide phase can be used as a unique way of introducing organic additives into the bulk metal oxide materials. These organic additives can cause the generation of gas upon ignition of the materials, therefore resulting in a composite material that can perform pressure/volume work. Furthermore, the desired organic functionality is well dispersed throughout the composite material on the nanoscale with the other components, and is therefore subject to the same increased reaction kinetics. The resulting nanoscale distribution of all the ingredients displays energetic properties not seen in its microscale counterparts due to the expected increase of mass transport rates between the reactants. The synthesis and characterization of iron(III) oxide/organosilicon oxide nanocomposites and their performance as energetic materials will be discussed.

  13. High-throughput synthesis of mixed-metal electrocatalysts for CO{sub 2} reduction

    Energy Technology Data Exchange (ETDEWEB)

    He, Jingfu; Dettelbach, Kevan E.; Li, Tengfei [Department of Chemistry, The University of British Columbia, Vancouver, BC (Canada); Salvatore, Danielle A. [Department of Chemical and Biological Engineering, The University of British Columbia, Vancouver, BC (Canada); Berlinguette, Curtis P. [Department of Chemistry, The University of British Columbia, Vancouver, BC (Canada); Department of Chemical and Biological Engineering, The University of British Columbia, Vancouver, BC (Canada)

    2017-05-22

    The utilization of CO{sub 2} as a feedstock requires fundamental breakthroughs in catalyst design. The efficiencies and activities of pure metal electrodes towards the CO{sub 2} reduction reaction are established, but the corresponding data on mixed-metal systems are not as well developed. In this study we show that the near-infrared driven decomposition (NIRDD) of solution-deposited films of metal salts and subsequent electrochemical reduction offers the unique opportunity to form an array of mixed-metal electrocatalyst coatings with excellent control of the metal stoichiometries. This synthetic method enabled us to develop an empirical structure-property correlation to help inform the development of optimized CO{sub 2} catalyst compositions. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. A biomimicing approach to the mixed ligand complexes of bivalent transition metal

    Directory of Open Access Journals (Sweden)

    Bipin Bihari Prasad

    2013-03-01

    Full Text Available Metal complexes of the type ML1L2[M=Cu(II, Ni(II, and Co(II, L1=,'-dipyridyl(dipy., L2=2-hydroxybenzalidine anthranilic acid (HBAA] have been synthesized by using ,'-dipyridyl(dipy., 2-hdroxybenzalidine anthranilic acid (HBAA and metal(II acetate. The resulting mixed ligand metal complexes have been characterized on the basis of elemental analysis, IR-spectra, electronic spectra, magnetic susceptibilities and molar conductance measurements. The antifungal and antibacterial activities of ligands and there metal complexes have been screened against Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Escherichia coli and Staphylococcus aureus.

  15. Heavy metal-immobilizing organoclay facilitates polycyclic aromatic hydrocarbon biodegradation in mixed-contaminated soil.

    Science.gov (United States)

    Biswas, Bhabananda; Sarkar, Binoy; Mandal, Asit; Naidu, Ravi

    2015-11-15

    Soils contaminated with a mixture of heavy metals and polycyclic aromatic hydrocarbons (PAHs) pose toxic metal stress to native PAH-degrading microorganisms. Adsorbents such as clay and modified clay minerals can bind the metal and reduce its toxicity to microorganisms. However, in a mixed-contaminated soil, an adsorption process more specific to the metals without affecting the bioavailability of PAHs is desired for effective degradation. Furthermore, the adsorbent should enhance the viability of PAH-degrading microorganisms. A metal-immobilizing organoclay (Arquad(®) 2HT-75-bentonite treated with palmitic acid) (MIOC) able to reduce metal (cadmium (Cd)) toxicity and enhance PAH (phenanthrene) biodegradation was developed and characterized in this study. The MIOC differed considerably from the parent clay in terms of its ability to reduce metal toxicity (MIOC>unmodified bentonite>Arquad-bentonite). The MIOC variably increased the microbial count (10-43%) as well as activities (respiration 3-44%; enzymatic activities up to 68%), and simultaneously maintained phenanthrene in bioavailable form in a Cd-phenanthrene mixed-contaminated soil over a 21-day incubation period. This study may lead to a new MIOC-assisted bioremediation technique for PAHs in mixed-contaminated soils.

  16. Pseudotetragonal structure of Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50): the first mixed valence cerium fluoride.

    Science.gov (United States)

    Renaudin, Guillaume; Dieudonné, Belto; Avignant, Daniel; Mapemba, Elise; El-Ghozzi, Malika; Fleutot, Solène; Martinez, Hervé; Cerný, Radovan; Dubois, Marc

    2010-01-18

    The crystal structure of the new Li(5.5)Ce(12)F(50) compound has been fully characterized by single-crystal and synchrotron powder X-ray diffraction. An accurate pseudotetragonal structure was described in the monoclinic P2(1) space group with 68 independent crystallographic sites. The Li(5.5)Ce(12)F(50) composition belongs to the Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50) solid solution. Its structure consists of an opened fluorine framework where a channel network allows the intercalation of relatively mobile lithium cations, inducing the formation of the mixed-valence cerium (the intercalation of Li(+) leads to the reduction of a part of Ce(4+) to Ce(3+)). One part of the lithium ions, necessary for the electroneutrality of the tetravalent equivalent cerium fluoride (Li(2)Ce(12)F(50) composition), is in a locked fluorine polyhedron. Only the supplementary x amount of lithium is able to be exchanged in Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50). The structure of Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50) is a rearrangement, due to lithium intercalation, of the base CeF(4) structure. Bond valence calculation on Ce sites, Ce coordination polyhedra volumes, and a calculated Ce cationic radius give the indication of a partial long-range ordering of trivalent and tetravalent cerium cations in specific slabs of the structure. (7)Li NMR spectroscopy and XPS analyses have confirmed all of the structure details.

  17. The effect of mixing on metallicity gradients in the ICM

    CERN Document Server

    Brüggen, M

    2002-01-01

    It is generally argued that most clusters of galaxies host cooling flows in which radiative cooling in the centre causes a slow inflow. However, recent observations by Chandra and XMM conflict with the predicted cooling flow rates. It has been suggested that radio jets that are situated at the centre of clusters of galaxies can assist in reducing the deposition of cold gas. Radio jets inflate cavities of hot radio plasma that rise through the cluster atmosphere and thus stir the intra-cluster medium. In this letter it is investigated whether this scenario is consistent with the pronounced metallicity gradients that have been observed in the cores of clusters.

  18. Turbulent metal-silicate mixing, fragmentation, and equilibration in magma oceans

    CERN Document Server

    Deguen, Renaud; Olson, Peter

    2014-01-01

    Much of the Earth was built by high-energy impacts of planetesimals and embryos, many of these impactors already differentiated, with metallic cores of their own. Geochemical data provide critical information on the timing of accretion and the prevailing physical conditions, but their interpretation depends critically on the degree of metal-silicate chemical equilibration during core-mantle differentiation, which is poorly constrained. Efficient equilibration requires that the large volumes of iron derived from impactor cores mix with molten silicates down to scales small enough to allow fast metal-silicate mass transfer. Here we use fluid dynamics experiments to show that large metal blobs falling in a magma ocean mix with the molten silicate through turbulent entrainment, with fragmentation into droplets eventually resulting from the entrainment process. In our experiments, fragmentation of the dense fluid occurs after falling a distance equal to 3-4 times its initial diameter, at which point a sizable volu...

  19. Metal extraction from the artificially contaminated soil using supercritical CO2 with mixed ligands.

    Science.gov (United States)

    Park, Kwangheon; Lee, Jeongken; Sung, Jinhyun

    2013-04-01

    Supercritical fluids have good penetrating power with a high capacity to dissolve certain solutes in the fluid itself, making it applicable for soil cleaning. Supercritical CO2 along with mixed ligands has been used for cleaning artificially contaminated soil. The extraction of metal from the soil was successful, and the molar ratio of ligands to the extracted metal was as low as 3. Complicated structures with a large surface area of the real soil seemed to cause the lower efficiency. Reduced efficiency was also observed over time after the sample preparation, indicating the possibility of chemisorption of the metal ion onto the soil. The use of supercritical CO2 with dissolved mixed ligands was sufficient to extract metal from the soil. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Thermodynamic Properties and Mixing Thermodynamic Parameter of Binary Metallic Melt Involving Compound Formation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jian

    2005-01-01

    Based on the coexistence theory of metallic melts involving compound formation,the theoretical cal culation equations of mixing thermodynamic parameters are established by giving up some empirical parameters in the associated solution model.For Fe-Al,Mn-Al and Ni-Al,the calculated results agree well with the experimental values,testifying that these equations can exactly embody mixing thermodynamic characteristics of these melts.

  1. Observation of a mixed-metal transition in heterobimetallic Au/Ag dicyanide systems.

    Science.gov (United States)

    Hettiarachchi, Samanthika R; Schaefer, Brian K; Yson, Renante L; Staples, Richard J; Herbst-Irmer, Regine; Patterson, Howard H

    2007-08-20

    Crystals of the mixed-metal heterobimetallic Au/Ag dicyanide complex, K[AuxAg1-x(CN)2] (x = 0-->1), were obtained by slow evaporation. The mixed-metal complex K[Au0.44Ag0.56(CN)2] crystallizes in a rhombohedral crystal system, space group R. The crystal structure consists of layers of linear chains of Au(CN)2- and Ag(CN)2- ions and K+ ions that connect the layers through the N atoms. The excitation and emission spectra of single crystals of K[AuxAg1-x(CN)2] were recorded at 4.2-180 K using excitation wavelengths between 230 and 260 nm. Two emission bands due to Ag-Au interactions were observed at 343 and 372 nm. Lifetime measurements indicate the shorter-wavelength emission corresponds to fluorescence and the longer-wavelength band is phosphorescence. These new emission bands are not seen in the pure K[Ag(CN)2] or pure K[Au(CN)2] crystals. Extended Hückel calculations show that the LUMO of the mixed-metal system is bonding while the HOMO is antibonding or very weakly bonding. Moreover, excited-state extended Hückel calculations indicate the formation of exciplexes with shorter metal-metal distances and higher metal-metal overlap populations than the corresponding ground-state oligomers. The luminescence is assigned to a mixed-metal transition from a molecular orbital with Au character to a molecular orbital with Ag character.

  2. Fluoride release from newly marketed fluoride varnishes.

    Science.gov (United States)

    Jablonowski, Beth L; Bartoloni, Joseph A; Hensley, Donna M; Vandewalle, Kraig S

    2012-03-01

    New fluoride varnishes have been marketed that reportedly release more fluoride (Enamel Pro) or release fluoride more slowly (Vanish XT). The purpose of this study was to compare the amount and rate of fluoride release of new fluoride varnishes with other traditional fluoride varnishes. Extracted molars were cut into block sections. The enamel surfaces of the sections were painted with Enamel Pro, Duraphat, Vanish, or Vanish XT fluoride varnishes. One group was not treated and served as a negative control. The tooth sections were immersed in artificial saliva. The concentration of fluoride in parts per million was measured after the first 30 minutes, daily for the first week, and weekly until the level was below the limit of detection. Fluoride release was plotted over time. Cumulative fluoride release and rate of release (slope) were analyzed using one-way ANOVA/Tukey (α = .05). Enamel Pro had the greatest cumulative fluoride release. There was no significant difference between Duraphat and Vanish. Vanish XT had the lowest cumulative fluoride release. The rate of fluoride release from 1 week to limit of detection was Enamel Pro > Vanish > Duraphat > Vanish XT. The two newly marketed fluoride varnishes (Enamel Pro and Vanish XT) had significantly different fluoride release from the two conventional fluoride varnishes (Duraphat and Vanish).

  3. Thermodynamic properties and mixing thermodynamic parameters of binary homogeneous metallic melts

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    After the investigation on the thermodynamic properties and mixing thermodynamic parameters of binary ho-mogeneous metallic melts involving compound, peritectic as well as solid solution, it was found that the equations of mix-ing free energy ΔGm and excess free energy ΔGxs of them can be expressed by the following equations:ΔGm = ∑x[∑NiΔGiθ + RT(∑ Nj ln Nj+∑Ni lnNi)] and ΔGxs = ΔGm-RT(alna+blnb), respectively.

  4. Optical properties of single-walled carbon nanotubes highly separated in semiconducting and metallic tubes functionalized with poly(vinylidene fluoride)

    Science.gov (United States)

    Matea, A.; Baibarac, M.; Baltog, I.

    2017-02-01

    In this paper, the interaction of poly(vinylidene fluoride) (PVDF) with single-walled carbon nanotubes (SWNTs) highly separated in metallic (M) and semiconducting (S) tubes is studied by resonant Raman scattering and FTIR spectroscopy. In this order, the PVDF/SWNTs membranes were prepared by the evaporation of dimethylformamide (DMF) from PVDF solutions containing i) the as-prepared SWNTs samples, i.e., as mixtures of metallic (33%) and semiconducting (66%) tubes (M + S-SWNTs), ii) SWNTs highly separated in metallic tubes (98%, M-SWNTs), and iii) SWNTs highly separated in semiconducting tubes (99%, S-SWNTs). An increase in the PVDF β phase weight, highlighted by the increase in the absorbance of IR band at 843 cm-1, is reported to take place in the presence of M + S-SWNTs and S-SWNTs. An increase of the PVDF γ crystalline phase weight is reported for the PVDF/M + S-SWNTs, PVDF/M-SWNTs and PVDF/S-SWNTs membranes. Using Raman scattering, a donor-acceptor interaction is invoked to take place at the interface PVDF/M + S-SWNTs and PVDF/S-SWNTs. In the case of the membranes based on PVDF and M-SWNTs, the changes reported in Raman spectra of the two constituents are explained on the base induction-interaction forces between the permanent dipole of PVDF and induced dipole of M-SWNTs.

  5. Application of vacuum metallurgy to separate pure metal from mixed metallic particles of crushed waste printed circuit board scraps.

    Science.gov (United States)

    Zhan, Lu; Xu, Zhenming

    2008-10-15

    The principle of separating pure metal from mixed metallic particles (MMPs) byvacuum metallurgy is that the vapor pressures of various metals at the same temperature are different As a result, the metal with high vapor pressure and low boiling point can be separated from the mixed metals through distillation or sublimation, and then it can be recycled through condensation under a certain condition. The vacuum metallurgy separation (VMS) of MMPs of crushed waste printed circuit boards (WPCBs) has been studied in this paper. Theoretical analyses show that the MMPs (copper, zinc, bismuth, lead, and indium, for example) can be separated by vacuum metallurgy. The copper particles (0.15-0.20 mm) and zinc particles (<0.30 mm) were chosen to simulate the MMPs of crushed WPCBs. Experimental results show that the separated efficiency of zinc in the copper-rich particles achieves 96.19 wt % when the vacuum pressure is 0.01-0.10 Pa, the heating temperature is 1123 K, and the heating time is 105 min. Under this operation condition, the separated efficiency of zinc in the copper-rich particles from crushed WPCBs achieves 97.00 wt % and the copper purity increases from 90.68 to 99.84 wt %.

  6. MIXED-METAL COMPLEXES OF MIXED-VALENT DINUCLEAR RUTHENIUM(II,III CARBOXYLATE AND TETRACYANIDONICKELATE(II

    Directory of Open Access Journals (Sweden)

    Masahiro Mikuriya

    2014-06-01

    Full Text Available Mixed-metal chain complexes constructed from lantern-type dinuclear ruthenium(II,III carboxylate unit and tetracyanidonickelate(II, (PPh4n[Ru2(O2CCH34Ni(CN4]n•nH2O (1 and (PPh4n[Ru2{O2CC(CH33}4]3n[Ni(CN4]2n•2nH2O (2, where very weak antiferromagnetic interaction is operating, were synthesized and characterized by elemental analysis and IR and UV-vis spectroscopies and temperature dependence of magnetic susceptibilities (4.5—300K.

  7. Synthesis of metallic glasses and metallic glass based composites in the Cu-Mo-Hf system by ion beam mixing

    Institute of Scientific and Technical Information of China (English)

    BAI Xue; WANG TongLe; CUI YuanYuan; DING Ning; LI JiaHao; LIU BaiXin

    2012-01-01

    Single-phase and dual-phase metallic glasses as well as metallic glass based composites were synthesized in the Cu-Mo-Hf ternary metal system by 200 keV xenon ion beam mixing of far-from-equilibrium.It was found that Mo-Hf-based and Cu-Mo-based single-phase metallic glasses could be obtained at compositions around Cu17Mo20Hf63 and Cu34Mo57Hf9,respectively.Interestingly,at the nearly equal-atomic stoichiometry of Cu38Mo31Hf31,a dual-phase Cu-Mo-Hf metallic glass,consisting both of the Mo-Hf-based and Cu-Mo-based phases,was first obtained at relatively low irradiation doses ranging from (1-5)×1015 Xe+/cm2,and a single-phase metallic glass was eventually obtained at a dose of 7×1015 Xe+/cm2.In addition,two glass-based composites were obtained at the compositions of Cu14Mo62Hf24 and Cu77Mo14Hf9,and they consisted of the Mo-Hf based and Cu-Mo based metallic glasses,dissolved with some uniformly distributed BCC Mo-based and FCC Cu-based crystalline solid solutions,respectively.The formation mechanism of the above described non-equilibrium alloy phases was also discussed in terms of the atomic collision theory.

  8. Fluoridation Basics

    Science.gov (United States)

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

  9. Protective conversion coating on mixed-metal substrates and methods thereof

    Energy Technology Data Exchange (ETDEWEB)

    O' Keefe, Matthew J.; Maddela, Surender

    2016-09-06

    Mixed-metal automotive vehicle bodies-in-white comprising ferrous metal surfaces, zinc surfaces, aluminum alloy surfaces, and magnesium alloy surfaces are cleaned and immersed in an aqueous bath comprising an adhesion promoter and an aqueous electrocoat bath (the adhesion promoter may be in the electrocoat bath. The adhesion promoter, which may be a cerium salt, is selected to react with each metal in the body surfaces to form an oxide layer that provides corrosion resistance for the surface and adherence for the deposited polymeric paint coating. The body is cathodic in the electrocoat deposition.

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

    Directory of Open Access Journals (Sweden)

    Rajković Miloš B.

    2007-01-01

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

  11. Ceria doped mixed metal oxide nanoparticles as oxidation catalysts: Synthesis and their characterization

    Directory of Open Access Journals (Sweden)

    S.S.P. Sultana

    2015-11-01

    Full Text Available Mixed metal nanoparticles (NPs have attracted significant attention as catalysts for various organic transformations. In this study, we have demonstrated the preparation of nickel–manganese mixed metal oxide NPs doped with X% nano cerium oxide (X = 1, 3, 5 mol% by a facile co-precipitation technique using surfactant and surfactant free methodologies. The as-synthesized materials were calcined at different temperatures (300 °C, 400 °C, and 500 °C, and were characterized using various spectroscopic techniques, including, FTIR and XRD. SEM analysis, TEM analysis and TGA were employed to evaluate the structural properties of the as-prepared catalyst. These were evaluated for their catalytic behaviour towards the conversion of benzyl alcohol to benzaldehyde, which was used as a model reaction with molecular oxygen as oxidant. Furthermore, the effect of the variation of the percentage of nano ceria doping and the calcination temperature on the performance of as-prepared mixed metal catalysts was also evaluated. The kinetic studies of the reactions performed employing gas chromatographic technique have revealed that the mixed metal oxide catalyst doped with 5% nano ceria displayed excellent catalytc activity, among various catalysts synthesized.

  12. Thermohaline mixing and gravitational settling in carbon-enhanced metal-poor stars

    NARCIS (Netherlands)

    Stancliffe, R.J.; Glebbeek, E.|info:eu-repo/dai/nl/30483324X

    2008-01-01

    We investigate the formation of carbon-enhanced metal-poor (CEMP) stars via the scenario of mass transfer from a carbon-rich asymptotic giant branch primary to a low-mass companion in a binary system. We explore the extent to which material accreted from a companion star mixes with that of the recip

  13. Processing of mixed uranium/refractory metal carbide fuels for high temperature space nuclear reactors

    Science.gov (United States)

    Knight, Travis; Anghaie, Samim

    2000-01-01

    Single phase, solid-solution mixed uranium/refractory metal carbides have been proposed as an advanced nuclear fuel for high performance, next generation space power and propulsion systems. These mixed carbides such as the pseudo-ternary, (U, Zr, Nb)C, hold significant promise because of their high melting points (typically greater than 3200 K), thermochemical stability in a hot hydrogen environment, and high thermal conductivity. However, insufficient test data exist under nuclear thermal propulsion conditions of temperature and hot hydrogen environment to fully evaluate their performance. Various compositions of (U, Zr, Nb)C were processed with 5% and 10% metal mole fraction of uranium. Stoichiometric samples were processed from the constituent carbide powders while hypostoichiometric samples with carbon-to-metal (C/M) ratios of 0.95 were processed from uranium hydride, graphite, and constituent refractory carbide powders. Processing techniques of cold pressing, sintering, and hot pressing were investigated to optimize the processing parameters necessary to produce dense (low porosity), homogeneous, single phase, solid-solution mixed carbide nuclear fuels for testing. This investigation was undertaken to evaluate and characterize the performance of these mixed uranium/refractory metal carbides for space power and propulsion applications. .

  14. The Impact of Carbon Enhancement on Extra Mixing in Metal-Poor Stars

    CERN Document Server

    Denissenkov, Pavel A

    2007-01-01

    We critically examine the constraints imposed by carbon-enhanced metal-poor (CEMP) stars on the mixing mechanisms that operate in red giants. CEMP stars are created when the surface layers of a metal-poor dwarf are enriched with He-burning products via mass transfer from an evolved donor. The difference between main sequence (MS) and red giant CEMP abundances can be used as a diagnostic of the timescale for the mixing of the processed material into stellar interiors on the MS. Abundance trends with luminosity among red giant CEMP stars test theories of canonical extra mixing for low mass giants with a high bulk metallicity. We find a significant dilution in CN enrichment in giant CEMP stars relative to their MS precursors, and take this as evidence that thermohaline mixing induced by mean molecular weight inversions is ineffective in CEMP stars. This contradicts models that rely on efficient thermohaline mixing induced by small mu gradients in red giants, because such models would predict that MS CEMP stars w...

  15. Molten fluorides for nuclear applications

    Directory of Open Access Journals (Sweden)

    Sylvie. Delpech

    2010-12-01

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

  16. Metal-free flat lens using negative refraction by nonlinear four-wave mixing.

    Science.gov (United States)

    Cao, Jianjun; Zheng, Yuanlin; Feng, Yaming; Chen, Xianfeng; Wan, Wenjie

    2014-11-21

    A perfect lens with unlimited resolution has always posed a challenge to both theoretical and experimental physicists. Recent developments in optical metamaterials promise an attractive approach towards perfect lenses using negative refraction to overcome the diffraction limit, improving resolution. However, those artificially engineered metamaterials are usually accompanied by high losses from metals and are extremely difficult to fabricate. An alternative proposal using negative refraction by four-wave mixing has attracted much interest recently, though most existing experiments still require metals and none of them have been implemented for an optical lens. Here, we experimentally demonstrate a metal-free flat lens for the first time using negative refraction by degenerate four-wave mixing with a thin glass slide. We realize an optical lensing effect utilizing a nonlinear refraction law, which may have potential applications in microscopy.

  17. Metal-Free Flat Lens Using Negative Refraction by Nonlinear Four-wave Mixing

    CERN Document Server

    Cao, Jianjun; Feng, Yaming; Chen, Xianfeng; Wan, Wenjie

    2014-01-01

    A perfect lens with unlimited resolution has always posed a challenge to both theoretical and experimental physicists. Recent developments in optical meta-materials promise an attractive approach towards perfect lenses using negative refraction to overcome the diffraction limit, improving resolution. However, those artificially engineered meta-materials usually company by high losses from metals and are extremely difficult to fabricate. An alternative proposal on using negative refraction by four-wave mixing has attracted much interests recently, though most of existing experiments still require metals and none of them has been implemented for an optical lens. Here we experimentally demonstrate a metal-free flat lens for the first time using negative refraction by degenerate four-wave mixing with a simple thin glass slide. We realize optical lensing utilizing a nonlinear refraction law, which may have potential applications in infrared microscopy and super-resolution imaging.

  18. Encapsulation of ZnO particles by metal fluorides: Towards an application as transparent insulating coatings for windows

    Science.gov (United States)

    Trenque, Isabelle; Mornet, Stéphane; Duguet, Etienne; Majimel, Jérôme; Brüll, Annelise; Teinz, Katharina; Kemnitz, Erhard; Gaudon, Manuel

    2013-01-01

    Because ZnO is a promising candidate for getting efficient films or varnishes with thermal insulating abilities for windows applications, the effect of the encapsulation of ZnO particles in shells of low refractive index material on the improvement of the visible light transmission was investigated. ZnO-MgF2 core-shell particles were synthesized by deposition of fluoride sols on ZnO particles through a vacuum slip casting process like. The transmission behaviours were first indirectly studied by diffuse reflexion measurements on powder beds. Then, particle films were elaborated by a screen printing process which ensured direct transmission measurements. The encapsulation of ZnO particles with a coating shell of 1.3 wt.% of MgF2 improves the visible light transmission of 32%.

  19. The comparison of calculated transition probabilities with luminescence characteristics of erbium(III) in fluoride glasses and in the mixed yttrium-zirconium oxide crystal

    Science.gov (United States)

    Reisfeld, R.; Katz, G.; Jacoboni, C.; De Pape, R.; Drexhage, M. G.; Brown, R. N.; Jørgensen, C. K.

    1983-07-01

    Fluorozirconate glasses containing 2 mole% ErF 3 were prepared by melting the binary fluorides with ammonium bifluoride under an atmosphere of carbon tetrachloride and argon at 850°C. Absorption spectra of these glasses were obtained and the Judd-Ofelt parameters were calculated. Emission spectra and lifetimes of erbium in fluorozirconate glass, in lead-gallium-zinc fluoride glass, and in yttrium-zirconium oxide crystal were measured and compared with the theoretical calculations. Laser emission lines in these materials are deduced from these measurements. It is suggested that materials doped with erbium may serve as light sources for fiber optic waveguides made from the undoped materials.

  20. [Enamel fluoride uptake following fluoride application and fluoride precipitation].

    Science.gov (United States)

    Buchalla, Wolfgang; Lennon, Aine M; Trage, Katrin; Becker, Klaus; Attin, Thomas

    2007-01-01

    This study is on fluoride uptake into enamel following fluoride precipitation with calcium hydroxide. Five specimens each from 12 bovine incisors were polished, covered with a salivary pellicle, and distributed into five groups (n=12). A fluoride solution (43,500 ppm F from magnesiumfluorosilicate, copper-(II)-fluorosilicate and sodium-fluoride, pH 2; Tiefenfluorid Touchierlösung, Humanchemie) and Ca(OH)2-solution (Tiefenfluorid Nachtouchierlösung) were applied subsequently in group TN. "Touchierlosung" only was used in group T, sodium-fluoride (43,500 ppm F, pH 2) in group NaF, and aminefluoride (Elmex fluid, 10,000 ppm F, pH 4) in group EF. No fluoride was used in group NK (negative control). Following rinsing and 24 h storage in artificial saliva surface KOH-soluble fluoride content (KOHF), and structurally bound fluoride content (SBF) from three layers (0-33, 33-66 and 66-99 pm) was determined by fluoride electrode procedures. KOHF (median in microg/cm2) of NK was below the lower limit of quantification of the fluoride electrode. The other group values were significantly higher (Mann-Whitney test, p precipitation reaction with Ca(OH)2 following fluoridation did not increase enamel fluoride uptake.

  1. Application of Hard Metal Weld Deposit in the Area of Mixing Organic Materials

    Directory of Open Access Journals (Sweden)

    Jiří Votava

    2014-01-01

    Full Text Available Any machine part is subject to degradation processes. Intensive wear occurs either when two bearing surfaces come into contact or when loose particles rub the function surface of a machine part. Soil processing machines are a good example. A similar process of abrasive wear occurs also in mixing machines or lines for material transport, such as worm-conveyors. The experiment part of this paper analyses hard metal weld deposit dedicated for renovation of abrasive stressed surfaces. In order to prolong the service life of a blade disc in a mixing machine Kreis-Biogas-Dissolver, the technology of hard surfacing by an electric arc was used. Tested hard metal electrodes were applied on a steel tape class 11 373. To eliminate mixing with the base material, weld beads were applied in two layers. Firstly, the weld bead was visually analyzed on a binocular microscope. Further, weld bead as well as the base material was analyzed from the metallographic point of view, whose aim was to identify the structure of weld metal and the origin of microcracks in weld bead. Moreover, there was also measured microhardness of weld metal. Abrasive resistance was tested according to the norm ČSN 01 5084, which is an abrasive cloth test. As in the mixing process also erosion wear occurs, there was also processed a test on a Bond device simulating stress of test samples by loose abrasive particles. The abrading agents were formed by broken stones of 8–16 mm in size. Based on the results of the individual tests, the recommendation of usage hard metal electrodes for prolonging service life of machine parts will be made.

  2. Magnesium Fluoride Reduction Vessel Liners

    Science.gov (United States)

    1986-03-26

    Carolina Metals, the fluoride is reduced to power by means of a Mikro #2 hemmer mill (Figure 5). The material is then separated into the different...The jolter table previously referred to in the liner pro - ceasing operation, is the knockout station. As shown in Figure 36, the vessel is inverted...was much more extensive than normally performed to establish the quality of thý metal pro - duced using the MgF2 liners. There are no indications of

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

    Science.gov (United States)

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

    2014-01-01

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

  4. Transport and noise properties of a normal metal-superconductor-normal metal junction with mixed singlet and chiral triplet pairings

    Science.gov (United States)

    Paul, Ganesh C.; Dutta, Paramita; Saha, Arijit

    2017-01-01

    We study transport and zero frequency shot noise properties of a normal metal-superconductor-normal metal (NSN) junction, with the superconductor having mixed singlet and chiral triplet pairings. We show that in the subgapped regime when the chiral triplet pairing amplitude dominates over that of the singlet, a resonance phenomena emerges out at zero energy where all the quantum mechanical scattering probabilities acquire a value of 0.25. At the resonance, crossed Andreev reflection mediating through such junction, acquires a zero energy peak. This reflects as a zero energy peak in the conductance as well depending on the doping concentration. We also investigate shot noise for this system and show that shot noise cross-correlation is negative in the subgapped regime when the triplet pairing dominates over the singlet one. The latter is in sharp contrast to the positive shot noise obtained when the singlet pairing is the dominating one.

  5. Leaching heavy metals in municipal solid waste incinerator fly ash with chelator/biosurfactant mixed solution.

    Science.gov (United States)

    Xu, Ying; Chen, Yu

    2015-07-01

    The chelator [S,S]-ethylene diamine disuccinic acid, citric acid, and biosurfactant saponin are selected as leaching agents. In this study, the leaching effect of saponin mixed with either ethylene diamine disuccinic acid or citric acid on the levels of copper, zinc, lead, and cadmium in municipal solid waste incinerator fly ash is investigated. Results indicate that saponin separately mixed with ethylene diamine disuccinic acid and citric acid exhibits a synergistic solubilisation effect on copper, zinc, lead, and cadmium leaching from fly ash. However, saponin and ethylene diamine disuccinic acid mixed solution exhibits a synergistic solubilisation effect that is superior to that of a saponin and citric acid mixed solution. The extraction rate of heavy metal in fly ash leached with a saponin and chelator mixed solution is related to the pH of the leaching solution, and the optimal range of the pH is suggested to be approximately neutral. After leaching with a saponin and chelator mixed solution, copper, zinc, lead, and cadmium contents significantly decreased (p < 0.05) in the extractable or acid-soluble and reducible fractions. By adopting the proposed approach, the leaching concentrations of copper, zinc, lead, and cadmium in treated fly ash are in accordance with Standard for Pollution Control on the Security Landfill Site for Hazardous Wastes GB18598-2001.

  6. Spectral, thermal and X-ray studies on some new bis-hydrazine metal glyoxylates and bis-hydrazine mixed metal glyoxylates

    Energy Technology Data Exchange (ETDEWEB)

    Vikram, L. [Department of Chemistry, Government Arts College, Ooty, The Nilgiris, Udhagamandalam 643002 (India); Sivasankar, B.N. [Department of Chemistry, Government Arts College, Ooty, The Nilgiris, Udhagamandalam 643002 (India)]. E-mail: sivabickol@yahoo.com

    2007-01-01

    Bis-hydrazine complexes of metal glyoxylates and mixed metal glyoxylates of 3d-metal ions of the formula M(OOCCHO){sub 2}(N{sub 2}H{sub 4}){sub 2}, where M = Mg, Mn, Co, Ni, Cu, Zn or Cd and M{sub 1/3}Co{sub 2/3}(OOCCHO){sub 2}(N{sub 2}H{sub 4}){sub 2}, where M = Mg, Mn, Ni, Zn or Cd, respectively, have been prepared and studied. The compositions of the complexes have been determined by chemical analyses. The magnetic moments and electronic spectra suggest a high-spin octahedral geometry for the metal complexes. Infrared spectral data indicate the bidentate bridging by hydrazine molecules and monodentate coordination by glyoxylate ions in both the metal and mixed metal compounds. Thermogravimetry and differential thermal analyses in air have been used to study the thermal behaviour of the complexes. The simultaneous TG-DTA traces of all the complexes show multi-step deg.radation and the final products are found to be the respective metal oxides in the case of metal complexes and metal cobaltites in the case of mixed metal complexes. The final residues were identified by their X-ray powder diffraction patterns. X-ray powder diffraction patterns of the complexes including mixed metal complexes are almost superimposable with in each of the series indicating isomorphism. The metal cobaltites MCo{sub 2}O{sub 4}, where M = Mg, Mn, Ni, Zn or Cd were also prepared by decomposing the respective mixed metal complex in a pre-heated silica crucible at about 300 deg. C, and their identities were confirmed by chemical analyses, infrared spectra and X-ray powder diffraction.

  7. Persistence of Metal-rich Particles Downstream Zones of Acid Drainage Mixing in Andean Rivers

    Science.gov (United States)

    Pasten, P.; Montecinos, M.; Guerra, P. A.; Bonilla, C. A.; Escauriaza, C. R.; Dabrin, A.; Coquery, M.

    2016-12-01

    The Andes mountain range provides the setting for watersheds with high natural background of metals and for mining operations that enhance contaminant mobilization, notably in Northern and Central Chile. Dissolved and solid metal species are actively transported by streams to the Pacific Ocean from area and point sources, like acid drainage. We examine the response of metal rich particle suspensions downstream zones of mixing where shifts in the chemical environment occur. We propose a conceptual model which is used to analyze the fate of copper in the upper Mapocho watershed. The main source of copper is the Yerba Loca river, a naturally impacted stream with pH ranging from 3 to 7 and high concentrations of Cu (0.8 - 6.3 mg/L), Al (1.3 - 7.6 mg/L) and Fe (0.4 - 4.2 mg/L). Steep chemical shifts occur after the confluences with the San Francisco and the Molina rivers. We characterized stream chemistry, hydrological variables and suspended particles, including particle size distribution (PSD), turbidity, and total suspended solids. A marked seasonal behavior was observed, with a higher total Cu flux during smelting periods and a shift towards the dissolved phase during summer. When acid drainage is discharged into a receiving stream, incomplete mixing occurs thereby promoting the formation of a range of metal-rich solids with a characteristic PSD. Similarly, areas of chemical heterogeneity control the partition of metals associated to suspended geomaterials coming from bank and slope erosion. A highly dynamic process ensues where metastable phases shift to new equilibria as fully mixed conditions are reached. Depending on the reaction kinetics, some particles persist despite being exposed to thermodynamically unfavorable chemical environments. The persistence of metal-rich particles downstream zones of acid drainage mixing is important because it ultimately controls the flux of metals being delivered to the ocean by watersheds impacted by acid drainage. Funding from

  8. Structures and heats of formation of simple alkali metal compounds: hydrides, chlorides, fluorides, hydroxides, and oxides for Li, Na, and K.

    Science.gov (United States)

    Vasiliu, Monica; Li, Shenggang; Peterson, Kirk A; Feller, David; Gole, James L; Dixon, David A

    2010-04-01

    Geometry parameters, frequencies, heats of formation, and bond dissociation energies are predicted for simple alkali metal compounds (hydrides, chlorides, fluorides, hydroxides and oxides) of Li, Na, and K from coupled cluster theory [CCSD(T)] calculations including core-valence correlation with the aug-cc-pwCVnZ basis set (n = D, T, Q, and 5). To accurately calculate the heats of formation, the following additional correction were included: scalar relativistic effects, atomic spin-orbit effects, and vibrational zero-point energies. For calibration purposes, the properties of some of the lithium compounds were predicted with iterative triple and quadruple excitations via CCSDT and CCSDTQ. The calculated geometry parameters, frequencies, heats of formation, and bond dissociation energies were compared with all available experimental measurements and are in excellent agreement with high-quality experimental data. High-level calculations are required to correctly predict that K(2)O is linear and that the ground state of KO is (2)Sigma(+), not (2)Pi, as in LiO and NaO. This reliable and consistent set of calculated thermodynamic data is appropriate for use in combustion and atmospheric simulations.

  9. Fluoride retention in human enamel after a single phosphoric acid and mixed phosphoric acid/SnF2 application in vitro

    NARCIS (Netherlands)

    Kalter, P.G.E.; Flissebaalje, T.D.; Groeneveld, A.

    1980-01-01

    Pieces of enamel were treated with either an APF solution or a 1:1 mixture of APF/SnF2 (APF: 1.23 per cent F−, 0.1 M H3PO4; and SnF2: 2 per cent) for 4 min at 37 °C followed by 30 min washing. There was an increase of 1640 parts/106 in the fluoride concentration of APF-treated enamel. Most of the fl

  10. WITNESSING GAS MIXING IN THE METAL DISTRIBUTION OF THE HICKSON COMPACT GROUP HCG 31

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Flores, S.; Alfaro-Cuello, M. [Departamento de Física, Universidad de La Serena, Av. Cisternas 1200, La Serena (Chile); De Oliveira, C. Mendes [Instituto de Astronomia, Geofísica e Ciências Atmosféricas da Universidade de São Paulo, Cidade Universitária, CEP:05508-900, São Paulo, SP (Brazil); Amram, P. [Aix Marseille Université, CNRS, LAM (Laboratoire d' Astrophysique de Marseille) UMR 7326, F-13388, Marseille (France); Carrasco, E. R. [Gemini Observatory/AURA, Southern Operations Center, Casilla 603, La Serena (Chile); De Mello, D. F., E-mail: storres@dfuls.cl [Catholic University of America, Washington, DC 20064 (United States)

    2015-01-01

    We present for the first time direct evidence that in a merger of disk galaxies, the pre-existing central metallicities will mix as a result of gas being transported in the merger interface region along the line that joins the two coalescing nuclei. This is shown using detailed two-dimensional kinematics as well as metallicity measurements for the nearby ongoing merger in the center of the compact group HCG 31. We focus on the emission line gas, which is extensive in the system. The two coalescing cores display similar oxygen abundances. While in between the two nuclei, the metallicity changes smoothly from one nucleus to the other indicating a mix of metals in this region, which is confirmed by the high-resolution Hα kinematics (R = 45,900). This nearby system is especially important because it involves the merging of two fairly low-mass and clumpy galaxies (LMC-like galaxies), making it an important system for comparison with high-redshift galaxies.

  11. Explosive welding: Mixing of metals without mutual solubility (iron-silver)

    Science.gov (United States)

    Greenberg, B. A.; Ivanov, M. A.; Rybin, V. V.; Elkina, O. A.; Inozemtsev, A. V.; Volkova, A. Yu.; Kuz'min, S. V.; Lysak, V. I.

    2012-11-01

    The results obtained for joints of dissimilar metals, iron-silver (earlier, copper-tantalum), which form immiscible liquid suspensions, explain why they are mixed in explosive welding. Inhomogeneities of the wavy interface, such as protrusions and zones of localized melting, were observed. The effect of granulating fragmentation, which is responsible for crushing initial materials into particles, was understood as one of the most efficient ways to dissipate the supplied energy. It is shown that, in the case of joints of metals without mutual solubility, zones of localized melting represent colloidal solutions, which form either emulsions or suspensions. At solidification, the emulsion represents a hazard for joint stability due to possible separation; on the contrary, suspension can enable the dispersion strengthening of the joint. The results can be used in the development of new metal joints without mutual solubility.

  12. Designing mixed metal halide ammines for ammonia storage using density functional theory and genetic algorithms

    DEFF Research Database (Denmark)

    Jensen, Peter Bjerre; Lysgaard, Steen; Quaade, Ulrich J.

    2014-01-01

    Metal halide ammines have great potential as a future, high-density energy carrier in vehicles. So far known materials, e.g. Mg(NH3)6Cl2 and Sr(NH3)8Cl2, are not suitable for automotive, fuel cell applications, because the release of ammonia is a multi-step reaction, requiring too much heat...... to be supplied, making the total efficiency lower. Here, we apply density functional theory (DFT) calculations to predict new mixed metal halide ammines with improved storage capacities and the ability to release the stored ammonia in one step, at temperatures suitable for system integration with polymer...... electrolyte membrane fuel cells (PEMFC). We use genetic algorithms (GAs) to search for materials containing up to three different metals (alkaline-earth, 3d and 4d) and two different halides (Cl, Br and I) – almost 27000 combinations, and have identified novel mixtures, with significantly improved storage...

  13. High Sensitivity Transmission-Type SPR Sensor by Using Metallic-Dielectric Mixed Gratings

    Institute of Scientific and Technical Information of China (English)

    WU Bin; WANG Qing-Kang

    2008-01-01

    We theoretically investigate transmission-type SPR sensors with novel metallic-dielectric mixed gratings by rigorous coupled-wave analysis (RCWA),compared to the conventional dielectric gratings based structure.It is found that the transmittance efficiency and the full width at half-maximum (FWHM) of the transmission curve can be modulated by increasing or decreasing the metallic part.Therefore,appropriate proportion of metal part will induce enhancement factor of sensor merit.Furthermore,this novel structure will also bring enhancement of resonant angle shift,which can be explained by plasmonic interpretation based on a surface limited increase of interaction area and excitation of localized surface plasmons (LSPs).The proposed configuration has a wide range of potential applications not only as sensor but also other optical devices.

  14. Electrolytic decontamination of metal low level waste (LLW) and mixed low level waste (MLLW)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-11-01

    Metal objects resulting from ER activities were decontaminated using electrolytic methods. The project involved about 500 kg of ballistic test projectiles, 23 augers and drill heads, and 50 pieces of shrapnel containing lead. All objects were free-released and either reclaimed as scrap metal or reused. Electrolytic decontamination was proven to be an effective method to decontaminate metal waste objects to free-release standards. A cost analysis showed the process to be economical, especially when applied to decontamination of mixed waste, TRU waste, or when the recovered materials could be reused or recycled. The cost of decontamination of scrap iron is approximately equal to the cost of its land disposal as low level waste.

  15. Effects of enamel sealing on shear bond strength and the adhesive remnant index : Study of three fluoride-releasing adhesives in combination with metal and ceramic brackets.

    Science.gov (United States)

    Hofmann, Elisabeth; Elsner, Laura; Hirschfelder, Ursula; Ebert, Thomas; Hanke, Sebastian

    2017-01-01

    Selected combinations of materials were used to create tooth-adhesive-bracket complexes to evaluate shear bond strength (SBS) and the adhesive remnant index (ARI) with regard to enamel sealing. Four adhesive systems also appropriate for use as enamel sealants were combined with four bracket types, resulting in 16 adhesive-bracket combinations, each of which was tested on 15 permanent bovine incisors. Sealant-adhesives included two recently introduced fluoride-releasing systems (Riva bond LC(®) and go!(®)), one established primer (Opal(®) Seal™), and one commonly used adhesive as control (Transbond™ XT). Brackets included two metal (discovery(®) by Dentaurum and Sprint(®)) and two ceramic (discovery(®) pearl and GLAM(®)) systems. After embedding the bovine teeth, bonding the brackets to their surface, and storing the resultant samples as per DIN 13990-2 with modifications, an SBS test was performed by applying the shear force directly at the bracket base in an incisocervical direction. Then the ARI scores were determined. Discovery(®) + Transbond™ XT yielded the highest (47.2 MPa) and GLAM(®) + go!(®) the lowest (17.0 MPa) mean SBS values. Significant differences (p < 0.0001) were found between metal and ceramic brackets of the same manufacturers (Dentaurum and Forestadent). Our ratings of the failure modes upon debonding predominantly yielded ARI 0 or 1. The high SBS values and low ARI scores observed with discovery(®) + Transbond XT™ were reflected in a high rate of enamel fracture, which occurred on 11 of the 15 tooth specimens in this group. All sealant-bracket combinations were found to yield levels of SBS adequate for clinical application. SBS values and ARI scores varied significantly depending on which sealant-brackets were used.

  16. Studies of high temperature ternary phases in mixed-metal-rich early transition metal sulfide and phosphide systems

    Energy Technology Data Exchange (ETDEWEB)

    Marking, G.A.

    1994-01-04

    Investigations of ternary mixed early transition metal-rich sulfide and phosphide systems resulted in the discovery of new structures and new phases. A new series of Zr and Hf - group V transition metal - sulfur K-phases was synthesized and crystallographically characterized. When the group V transition metal was Nb or Ta, the unit cell volume was larger than any previously reported K-phase. The presence of adventitious oxygen was determined in two K-phases through a combination of neutron scattering and X-ray diffraction experiments. A compound Hf{sub 10}Ta{sub 3}S{sub 3} was found to crystallize in a new-structure type similar to the known gamma brasses. This structure is unique in that it is the only reported {open_quotes}stuffed{close_quotes} gamma-brass type structure. The metal components, Hf and Ta, are larger in size and more electropositive than the metals found in normal gamma brasses (e.g. Cu and Zn) and because of the larger metallic radii, sulfur can be incorporated into the structure where it plays an integral role in stabilizing this phase relative to others. X-ray single-crystal, X-ray powder and neutron powder refinements were performed on this structure. A new structure was found in the ternary Nb-Zr-P system which has characteristics in common with many known early transition metal-rich sulfides, selenides, and phosphides. This structure has the simplest known interconnection of the basic building blocks known for this structural class. Anomalous scattering was a powerful tool for differentiating between Zr and Nb when using Mo K{alpha} X-radiation. The compounds ZrNbP and HfNbP formed in the space group Prima with the simple Co{sub 2}Si structure which is among the most common structures found for crystalline solid materials. Solid solution compounds in the Ta-Nb-P, Ta-Zr-P, Nb-Zr-P, Hf-Nb-P, and Hf-Zr-S systems were crystallographically characterized. The structural information corroborated ideas about bonding in metal-rich compounds.

  17. Occupational fluoride exposure. [Review

    Energy Technology Data Exchange (ETDEWEB)

    Hodge, H.C. (Univ. of California, San Francisco); Smith, F.A.

    1977-01-01

    Effects of airborne fluoride on industrial health are discussed with regard to acute and chronic effects. Injuries to lungs and skin from acute exposures are described. Chronic effects are discussed with regard to industrial sources of fluoride and air concentrations vs. urinary concentrations of fluoride. An extensive literature review is presented in the form of a table showing responses in man exposed to industrial airborne fluorides. Osteosclerosis is discussed with regard to the fluoride air standard, bone fluoride, and air fluoride concentrations. Occupational exposures to fluoride are also discussed with regard to arthritis, shortness of breath, asthma, upper respiratory infections, chronic respiratory disease, effects on kidneys, effects on pregnancy, and indices of fluoride intoxication. A table is presented showing references to studies on responses in neighborhood residents exposed to fluoride emissions. (HLW)

  18. The action of uranium hexafluoride on some metallic fluorides (1962); Action de l'hexafluorure d'uranium sur quelques fluorures metalliques (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Michallet, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-12-15

    A metallic difluoride is inert to UF{sub 6} unless the metal can exist in a higher valency state. In this case, UF{sub 6} acts as an oxidising agent and is transformed into UF{sub 4}. The fluorides of tri- and tetra-valent metals give rise to new compounds when they are maintained at a high temperature (500 deg. C) in the presence of uranium hexachloride vapour. The products obtained are characterized by their X-ray diffraction diagrams. The distributions of the lines of the powder diagrams are very similar to that of U{sub 4}F{sub 17}. Assuming that this resemblance is due to a stacking of identical fluorine atoms, it can be calculated that the corresponding structure is given by the theoretical formulae: MeF{sub 3}, 0,562 UF{sub 6}; MeF{sub 4}, 0,396 UF{sub 6} which are in good agreement with chemical measurements. (author) [French] Un di-fluorure metallique est inerte vis-a-vis de UF{sub 6}, sauf si le metal est susceptible d'exister a une valence plus elevee. Dans ce cas, UF{sub 6} joue le role d'un oxydant et se transforme en UF{sub 4}. Les fluorures de metaux tri et tetravalents donnent naissance a des composes nouveaux quand ils sont maintenus a haute temperature (500 deg. C) en presence de vapeur d'hexafluorure d'uranium. Les produits obtenus sont caracterises par leurs diagrammes de diffraction X. Les distributions de raies des diagrammes de poudre sont tres voisines de celles de U{sub 4}F{sub 17}. En supposant que cette analogie resulte d'un empilement d'ions fluor identique, le calcul conduit aux formules theoriques suivantes: MeF{sub 3}, 0,562 UF{sub 6}; MeF{sub 4}, 0,396 UF{sub 6} en bon accord avec les resultats des dosages chimiques. (auteur)

  19. PT L 3 near edge structure of halogen-bridged mixed-valence pt complexes and pd-pt mixed-metal complexes

    Science.gov (United States)

    Tanino, H.; Oyanagi, H.; Yamashita, M.; Kobayashi, K.

    1985-03-01

    X-ray absorption near edge structure (XANES) of halogen-bridged mixed-valence Pt complexes and halogen-bridged Pd-Pt mixed-metal complexes have been measured using synchrotron radiation with a high energy resolution. In Pd-Pt mixed metal complexes, we demonstrate that the degree of the valence is estimated from the intensity of the white line at the Pt L 3 edge. In the mixed-valence complexes, the electron system is proved to be the Peierls insulator with a charge density wave of renormalized d electrons of Pt, where the total valence of Pt IV- and Pt 11 is conserved without excess electrons from ligands or anions.

  20. Vapor phase hydrogenation of furfural over nickel mixed metal oxide catalysts derived from layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Sulmonetti, Taylor P.; Pang, Simon H.; Claure, Micaela Taborga; Lee, Sungsik; Cullen, David A.; Agrawal, Pradeep K.; Jones, Christopher W.

    2016-05-01

    The hydrogenation of furfural is investigated over various reduced nickel mixed metal oxides derived from layered double hydroxides (LDHs) containing Ni-Mg-Al and Ni-Co-Al. Upon reduction, relatively large Ni(0) domains develop in the Ni-Mg-Al catalysts, whereas in the Ni-Co-Al catalysts smaller metal particles of Ni(0) and Co(0), potentially as alloys, are formed, as evidenced by XAS, XPS, STEM and EELS. All the reduced Ni catalysts display similar selectivities towards major hydrogenation products (furfuryl alcohol and tetrahydrofurfuryl alcohol), though the side products varied with the catalyst composition. The 1.1Ni-0.8Co-Al catalyst showed the greatest activity per titrated site when compared to the other catalysts, with promising activity compared to related catalysts in the literature. The use of base metal catalysts for hydrogenation of furanic compounds may be a promising alternative to the well-studied precious metal catalysts for making biomass-derived chemicals if catalyst selectivity can be improved in future work by alloying or tuning metal-oxide support interactions.

  1. Metallic Glass Formation by Ion Mixing and Calculation of Glass-Forming-Ability from Inter-Atomic Potential in the Binary Metal Systems

    Institute of Scientific and Technical Information of China (English)

    LI Zhengcao; LAI Wensheng; LIU Baixin

    2001-01-01

    In this article,a brief summary of the up-to-date progress of metallic glass formation by ion mixing of metallic multilayers in the binary metal systems is first presented.Secondly,thermodynamic modeling of metallic glass formation is developed with special consideration of the interfacial free energy of the multilayers.Thirdly,results of molecular dynamics simulations for some representative systems are presented to show the calculation of the glass-forming ability directly from the inter-atomic potential of the binary metal systems.

  2. Screening metal-organic framework-based mixed-matrix membranes for CO2/CH4 separations

    OpenAIRE

    Keskin, Seda; Eruçar, İlknur

    2011-01-01

    1 Screening Metal Organic Framework-based Mixed Matrix Membranes for CO2/CH4 Separations Ilknur Erucar† and Seda Keskin‡* †Department of Computational Sciences and Engineering, Koç University, 34450, Istanbul, Turkey ‡Department of Chemical and Biological Engineering, Koç University, 34450, Istanbul, Turkey Submitted to Ind. Eng. Chem. Res. Abstract In this study, the challenge of selecting metal organic frameworks (MOFs) as filler particles in high performance mixe...

  3. 含氟材料在金属防腐和表面防护方面的应用进展%Fluoride Materials for Metal Corrosion and Surface Protection

    Institute of Scientific and Technical Information of China (English)

    张兴凯; 郑锦华; 袁耀锋

    2015-01-01

    含氟材料具有独特的物理化学性能,如耐热性、拒水疏油性和耐腐蚀性,目前已大量应用到电子信息、化工及各类工程建筑等领域。本文简要介绍了含氟聚合物和含氟表面活性剂在金属防腐和表面防护方面的应用,并对比了几种材料在该应用领域的优缺点,提出了一些改进方法和措施,对提高含氟材料在金属表面防腐与防护性能有重要意义。%Fluoride materials possesses unique physical and chemical properties, such as heat resistance, water repellency oleophobic property and corrosion resistance, which has a large number of applications to the fields of electronic information industry, chemical industry and all kinds of engineering construction. After a brief introduction to the fluoride polymers and fluoride surfactants in the applications of metal corrosion and surface protection, some advantages and disadvantages of several kinds of fluoride materials in the field of application were compared. Some methods and measures for improvement were proposed, which had important significance to improve the performance of corrosion and protection in metal surface with containing-fluorine materials.

  4. Private Well Water and Fluoride

    Science.gov (United States)

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

  5. Fluoride and Water (For Parents)

    Science.gov (United States)

    ... Teaching Kids to Be Smart About Social Media Fluoride and Water KidsHealth > For Parents > Fluoride and Water ... in healthy tooth development and cavity prevention. About Fluoride Fluoride, which exists naturally in water sources, is ...

  6. Mixing along the Red Giant Branch in Metal-poor Field Stars

    CERN Document Server

    Carretta, E; Sneden, C; Bragaglia, A; Carretta, Eugenio; Gratton, Raffaele; Sneden, Chris; Bragaglia, Angela

    1999-01-01

    We have determined Li, C, N, O, Na, and Fe abundances, and 12C/13C isotopic ratios for a sample of 62 field metal-poor stars (plus 43 taken from the literature). This large sample was used to show that small mass lower-RGB stars (i.e., fainter than the RGB bump) have abundances of light elements in agreement with theoretical predictions from classical evolutionary models. A second, distinct mixing episode occurs just after the RGB bump, reaching regions of incomplete CNO burning. No O-Na anticorrelation, as observed in globular cluster stars, is found in field stars. This means that the mixing episode is not deep enough to reach regions where ON-burning occurs.

  7. Effects of Transition-Metal Mixing on Na Ordering and Kinetics in Layered P 2 Oxides

    Science.gov (United States)

    Zheng, Chen; Radhakrishnan, Balachandran; Chu, Iek-Heng; Wang, Zhenbin; Ong, Shyue Ping

    2017-06-01

    Layered P 2 oxides are promising cathode materials for rechargeable sodium-ion batteries. In this work, we systematically investigate the effects of transition-metal (TM) mixing on Na ordering and kinetics in the NaxCo1 -yMnyO2 model system using density-functional-theory (DFT) calculations. The DFT-predicted 0-K stability diagrams indicate that Co-Mn mixing reduces the energetic differences between Na orderings, which may account for the reduction of the number of phase transformations observed during the cycling of mixed-TM P 2 layered oxides compared to a single TM. Using ab initio molecular-dynamics simulations and nudged elastic-band calculations, we show that the TM composition at the Na(1) (face-sharing) site has a strong influence on the Na site energies, which in turn impacts the kinetics of Na diffusion towards the end of the charge. By employing a site-percolation model, we establish theoretical upper and lower bounds for TM concentrations based on their effect on Na(1) site energies, providing a framework to rationally tune mixed-TM compositions for optimal Na diffusion.

  8. The Role of Thermohaline Mixing in Intermediate- and Low-Metallicity Globular Clusters

    CERN Document Server

    Angelou, George C; Church, Ross P; Lattanzio, John C; Smith, Graeme H

    2012-01-01

    It is now widely accepted that globular cluster red giant branch stars owe their strange abundance patterns to a combination of pollution from progenitor stars and in situ extra mixing. In this hybrid theory a first generation of stars imprint abundance patterns into the gas from which a second generation forms. The hybrid theory suggests that extra mixing is operating in both populations and we use the variation of [C/Fe] with luminosity to examine how efficient this mixing is. We investigate the observed red giant branches of M3, M13, M92, M15 and NGC 5466 as a means to test a theory of thermohaline mixing. The second parameter pair M3 and M13 are of intermediate metallicity and our models are able to account for the evolution of carbon along the RGB in both clusters. Although, in order to fit the most carbon-depleted main-sequence stars in M13 we require a model whose initial [C/Fe] abundance leads to a carbon abundance lower than is observed. Furthermore our results suggest that stars in M13 formed with s...

  9. Asymmetric partitioning of metals among cluster anions and cations generated via laser ablation of mixed aluminum/Group 6 transition metal targets.

    Science.gov (United States)

    Waller, Sarah E; Mann, Jennifer E; Jarrold, Caroline Chick

    2013-02-28

    While high-power laser ablation of metal alloys indiscriminately produces gas-phase atomic ions in proportion to the abundance of the various metals in the alloy, gas-phase ions produced by moderate-power laser ablation sources coupled with molecular beams are formed by more complicated mechanisms. A mass spectrometric study that directly compares the mass distributions of cluster anions and cations generated from laser ablation of pure aluminum, an aluminum/molybdenum mixed target, and an aluminum/tungsten mixed target is detailed. Mass spectra of anionic species generated from the mixed targets showed that both tungsten and molybdenum were in higher abundance in the negatively charged species than in the target material. Mass spectra of the cationic species showed primarily Al(+) and aluminum oxide and hydroxide cluster cations. No molybdenum- or tungsten-containing cluster cations were definitively assigned. The asymmetric distribution of aluminum and Group 6 transition metals in cation and anion cluster composition is attributed to the low ionization energy of atomic aluminum and aluminum suboxide clusters. In addition, the propensity of both molybdenum and tungsten to form metal oxide cluster anions under the same conditions that favor metallic aluminum cluster anions is attributed to differences in the optical properties of the surface oxide that is present in the metal powders used to prepare the ablation targets. Mechanisms of mixed metal oxide clusters are considered.

  10. Rational design of metallic nanocavities for resonantly enhanced four-wave mixing

    CERN Document Server

    Almeida, Euclides

    2015-01-01

    Optimizing the shape of nanostructures and nano antennas for specific optical properties has evolved to be a very fruitful activity. With modern fabrication tools a large variety of possibilities is available for shaping both nanoparticles and nanocavities; in particular nanocavities in thin metal films have emerged as attractive candidates for new metamaterials and strong linear and nonlinear optical systems. Here we rationally design metallic nanocavities to boost their Four Wave Mixing response by resonating the optical plasmonic resonances with the incoming and generated beams. The linear and nonlinear optical responses as well as the propagation of the electric fields inside the cavities are derived from the solution of Maxwell equations by using the 3D finite-differences time domain method. The observed conversion-efficiency of near infra-red to visible light equals or surpasses that of BBO of equivalent thickness. Implications to further optimization for efficient and broadband ultrathin nonlinear opti...

  11. Rational design of metallic nanocavities for resonantly enhanced four-wave mixing

    Science.gov (United States)

    Almeida, Euclides; Prior, Yehiam

    2015-01-01

    Optimizing the shape of nanostructures and nano-antennas for specific optical properties has evolved to be a very fruitful activity. With modern fabrication tools a large variety of possibilities is available for shaping both nanoparticles and nanocavities; in particular nanocavities in thin metal films have emerged as attractive candidates for new metamaterials and strong linear and nonlinear optical systems. Here we rationally design metallic nanocavities to boost their Four-Wave Mixing response by resonating the optical plasmonic resonances with the incoming and generated beams. The linear and nonlinear optical responses as well as the propagation of the electric fields inside the cavities are derived from the solution of Maxwell’s equations by using the 3D finite-differences time domain method. The observed conversion-efficiency of near-infrared to visible light equals or surpasses that of BBO of equivalent thickness. Implications to further optimization for efficient and broadband ultrathin nonlinear optical materials are discussed. PMID:25974175

  12. Mixed-Metal Oxo Clusters Structurally Derived from Ti6O4(OR)8(OOCR')8.

    Science.gov (United States)

    Artner, Christine; Koyun, Ayse; Czakler, Matthias; Schubert, Ulrich

    2014-10-01

    The mixed-metal oxo clusters FeTi5O4(OiPr)4(OMc)10 (OMc = methacrylate), Zn2Ti4O4(OiPr)2(OMc)10, Cd4Ti2O2(OAc)2(OMc)10(HOiPr)2, [Ca2Ti4O4(OAc)2(OMc)10] n , and [Sr2Ti4O4(OMc)12(HOMc)2] n were obtained from the reaction of titanium alkoxides with the corresponding metal acetates and methacrylic acid. Their structures are derived from Ti clusters with the composition Ti6O4(OR)8(OOCR')8. The Ca and Sr derivatives consist of chains of condensed clusters.

  13. Mixed-Metal Oxo Clusters Structurally Derived from Ti6O4(OR)8(OOCR′)8

    Science.gov (United States)

    Artner, Christine; Koyun, Ayse; Czakler, Matthias; Schubert, Ulrich

    2014-01-01

    The mixed-metal oxo clusters FeTi5O4(OiPr)4(OMc)10 (OMc = methacrylate), Zn2Ti4O4(OiPr)2(OMc)10, Cd4Ti2O2(OAc)2(OMc)10(HOiPr)2, [Ca2Ti4O4(OAc)2(OMc)10]n, and [Sr2Ti4O4(OMc)12(HOMc)2]n were obtained from the reaction of titanium alkoxides with the corresponding metal acetates and methacrylic acid. Their structures are derived from Ti clusters with the composition Ti6O4(OR)8(OOCR′)8. The Ca and Sr derivatives consist of chains of condensed clusters. PMID:25814833

  14. Mixed transition-metal oxides: design, synthesis, and energy-related applications.

    Science.gov (United States)

    Yuan, Changzhou; Wu, Hao Bin; Xie, Yi; Lou, Xiong Wen David

    2014-02-03

    A promising family of mixed transition-metal oxides (MTMOs) (designated as Ax B3-x O4 ; A, B=Co, Ni, Zn, Mn, Fe, etc.) with stoichiometric or even non-stoichiometric compositions, typically in a spinel structure, has recently attracted increasing research interest worldwide. Benefiting from their remarkable electrochemical properties, these MTMOs will play significant roles for low-cost and environmentally friendly energy storage/conversion technologies. In this Review, we summarize recent research advances in the rational design and efficient synthesis of MTMOs with controlled shapes, sizes, compositions, and micro-/nanostructures, along with their applications as electrode materials for lithium-ion batteries and electrochemical capacitors, and efficient electrocatalysts for the oxygen reduction reaction in metal-air batteries and fuel cells. Some future trends and prospects to further develop advanced MTMOs for next-generation electrochemical energy storage/conversion systems are also presented.

  15. Rational design of metallic nanocavities for resonantly enhanced four-wave mixing.

    Science.gov (United States)

    Almeida, Euclides; Prior, Yehiam

    2015-05-14

    Optimizing the shape of nanostructures and nano-antennas for specific optical properties has evolved to be a very fruitful activity. With modern fabrication tools a large variety of possibilities is available for shaping both nanoparticles and nanocavities; in particular nanocavities in thin metal films have emerged as attractive candidates for new metamaterials and strong linear and nonlinear optical systems. Here we rationally design metallic nanocavities to boost their Four-Wave Mixing response by resonating the optical plasmonic resonances with the incoming and generated beams. The linear and nonlinear optical responses as well as the propagation of the electric fields inside the cavities are derived from the solution of Maxwell's equations by using the 3D finite-differences time domain method. The observed conversion-efficiency of near-infrared to visible light equals or surpasses that of BBO of equivalent thickness. Implications to further optimization for efficient and broadband ultrathin nonlinear optical materials are discussed.

  16. Gadolinium(III)-sensitized fluorescence of europium in its mixed-metal compounds with trifluroacetate

    Science.gov (United States)

    Kalinovskaya, I. V.; Zadorozhnaya, A. N.

    2017-04-01

    The fluorescence properties of mixed-metal compounds of Eu(III) and Gd(III) with trifluoroacetic acid, Eu1-xGdx(C2F3O2)3·yD·zH2O, where D - 1,10-phenanthroline, 2,2-dipyridil, diphenylguanidine, x = 0, 0.25, 0.5, or 0.7, were studied. Luminescence spectroscopic evidence and the examination of excitation spectra indicate the occurrence of efficient energy transfer from the gadolinium to the europium ion. The greatest promotion of Eu3+ photoluminescence at 615 nm is observed when Eu:Gd = 1:1.

  17. Rate sensitivity of mixed mode interface toughness of dissimilar metallic materials: Studied at steady state

    DEFF Research Database (Denmark)

    Nielsen, Kim Lau; Niordson, Christian Frithiof

    2012-01-01

    the SSV model [Suo, Z., Shih, C., Varias, A., 1993. A theory for cleavage cracking in the presence of plastic flow. Acta Metall. Mater. 41, 1551–1557] embedded in a steady state finite element formulation, here assuming plane strain conditions and small-scale yielding. Results are presented for a wide...... of the macroscopic fracture toughness under mixed Mode I/II loading. Moreover, special cases of joined similar rate dependent materials, as well as dissimilar materials where one substrate remains either elastic or approaches the rate independent limit is also included. The numerical analysis is carried out using...

  18. Fluoride varnish or fluoride mouth rinse?

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  19. Witnessing Gas Mixing in the Metal Distribution of the Hickson Compact Group HCG 31

    Science.gov (United States)

    Torres-Flores, S.; Mendes de Oliveira, C.; Amram, P.; Alfaro-Cuello, M.; Carrasco, E. R.; de Mello, D. F.

    2015-01-01

    We present for the first time direct evidence that in a merger of disk galaxies, the pre-existing central metallicities will mix as a result of gas being transported in the merger interface region along the line that joins the two coalescing nuclei. This is shown using detailed two-dimensional kinematics as well as metallicity measurements for the nearby ongoing merger in the center of the compact group HCG 31. We focus on the emission line gas, which is extensive in the system. The two coalescing cores display similar oxygen abundances. While in between the two nuclei, the metallicity changes smoothly from one nucleus to the other indicating a mix of metals in this region, which is confirmed by the high-resolution Hα kinematics (R = 45,900). This nearby system is especially important because it involves the merging of two fairly low-mass and clumpy galaxies (LMC-like galaxies), making it an important system for comparison with high-redshift galaxies. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina) - Observing run: GS-2012B-Q-60.

  20. Fluorite and mixed-metal Kagome-related topologies in metal-organic framework compounds: synthesis, structure, and properties.

    Science.gov (United States)

    Mahata, Partha; Raghunathan, Rajamani; Banerjee, Debamalya; Sen, Diptiman; Ramasesha, S; Bhat, S V; Natarajan, S

    2009-06-01

    Two new three-dimensional metal-organic frameworks (MOFs) [Mn(2)(mu(3)-OH)(H(2)O)(2)(BTC)] x 2 H(2)O, I, and [NaMn(BTC)], II (BTC = 1,2,4-benzenetricarboxylate = trimellitate) were synthesized and their structures determined by single-crystal X-ray diffraction (XRD). In I, the Mn(4) cluster, [Mn(4)(mu(3)-OH)(2)(H(2)O)(4)O(12)], is connected with eight trimellitate anions and each trimellitate anion connects to four different Mn(4) clusters, resulting in a fluorite-like structure. In II, the Mn(2)O(8) dimer is connected with two Na(+) ions through carboxylate oxygen to form mixed-metal distorted Kagome-related two-dimensional -M-O-M- layers, which are pillared by the trimellitate anions forming the three-dimensional structure. The extra-framework water molecules in I are reversibly adsorbed and are also corroborated by powder XRD studies. The formation of octameric water clusters involving free and coordinated water molecules appears to be new. Interesting magnetic behavior has been observed for both compounds. Electron spin resonance (ESR) studies indicate a broadening of the signal below the ordering temperature and appear to support the findings of the magnetic studies.

  1. Fluoride in diet

    Science.gov (United States)

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

  2. Mixed

    Directory of Open Access Journals (Sweden)

    Pau Baya

    2011-05-01

    Full Text Available Remenat (Catalan (Mixed, "revoltillo" (Scrambled in Spanish, is a dish which, in Catalunya, consists of a beaten egg cooked with vegetables or other ingredients, normally prawns or asparagus. It is delicious. Scrambled refers to the action of mixing the beaten egg with other ingredients in a pan, normally using a wooden spoon Thought is frequently an amalgam of past ideas put through a spinner and rhythmically shaken around like a cocktail until a uniform and dense paste is made. This malleable product, rather like a cake mixture can be deformed pulling it out, rolling it around, adapting its shape to the commands of one’s hands or the tool which is being used on it. In the piece Mixed, the contortion of the wood seeks to reproduce the plasticity of this slow heavy movement. Each piece lays itself on the next piece consecutively like a tongue of incandescent lava slowly advancing but with unstoppable inertia.

  3. Fluoride release and uptake capacities of fluoride-releasing restorative materials.

    Science.gov (United States)

    Attar, Nuray; Turgut, Melek D

    2003-01-01

    Many fluoride-releasing dental materials are being sold on the basis of their cariostatic properties. However, the amount fluoride release of these materials is still uncertain. This study investigated the fluoride release and uptake characteristics of four flowable resin composites (Heliomolar Flow, Tetric Flow, Wave, Perma Flo), one flowable compomer (Dyract flow), one conventional glass ionomer cement mixed with two different powder/liquid ratios (ChemFlex Syringeable and ChemFlex Condensable), one packable resin composite (SureFil), one ion-releasing composite (Ariston pHc) and one resin-modified glass ionomer cement (Vitremer). Seven discs (6-mm diameter and 1.5-mm height) were prepared for each material. Each disc was immersed in 3.5 ml of deionized water within a plastic vial and stored at 37 degrees C. The deionized water was changed every 24 hours and the release of fluoride was measured for 30 days. At the end of this period, the samples were recharged with 2 ml of 1.23% acidulated phosphate fluoride (APF) gel for four minutes. Then, all samples were reassessed for an additional 10 days. The fluoride release of all samples was measured with a specific fluoride electrode and an ionanalyzer. Statistical analyses were conducted using two-way repeated measure ANOVA and Duncan's multiple range tests. For all tested materials, the greatest fluoride release was observed after the first day of the study (p0.05). Ariston pHc released the highest amount of fluoride, followed by ChemFlex Syringeable, Vitremer and ChemFlex Condensable. There were statistically significant differences among these materials (p<0.05). Fluoride release of all materials were significantly increased after the first day following refluoridation and Ariston pHc released the greatest among all materials (p<0.01). At the end of two days of refluoridation, the fluoride release rate for each material dropped quickly and stabilized within three days.

  4. The role of ions, heavy metals, fluoride, and agrochemicals: critical evaluation of potential aetiological factors of chronic kidney disease of multifactorial origin (CKDmfo/CKDu) and recommendations for its eradication.

    Science.gov (United States)

    Wimalawansa, Sunil J

    2016-06-01

    The pollution of water and food through human waste and anthropogenic activities, including industrial waste and agricultural runoff, is a mounting problem worldwide. Water pollution from microbes causes identifiable diarrhoeal illnesses. The consumption of water contaminated with heavy metals, fluoride, and other toxins causes insidious illnesses that lead to protracted, non-communicable diseases and death. Chronic kidney disease of unusual/uncertain/unknown aetiology is one such example, began to manifest in the mid-1960s in several dry-zonal agricultural societies in developing economies that are located around the equator. In Sri Lanka, such a disease is affecting the North Central Province, the rice bowl of the country that first appeared in the mid-1990s. Several potential causes have been postulated, including heavy metals, fluoride, cyanobacterial and algae toxins, agrochemicals, and high salinity and ionicity in water, but no specific source or causative factor has been identified for CKD of multifactorial origin (CKDmfo). Three large studies conducted in the recent past failed to find any of the postulated components (heavy metals, cyanobacterial toxins, fluoride, salinity, or agrochemicals) at levels higher than those deemed safe by the World Health Organization and the US Environmental Protection Agency. At the reported low levels in water and with the heterogeneous geographical distribution, it is unrealistic to expect any of these components individually could cause this disease. However, the additive or synergistic effects of a combination of factors and components, even at lower exposure levels, together with malnutrition and harmful behaviours, and/or a yet-unidentified (or not investigated) toxin, can cause this epidemic. Because the cause is unknown, scientists need to work on broader hypotheses, so that key causative elements are not missed. Taken together the plausibility of multiple factors in the genesis of this disease, the appropriate

  5. Relationship between Composition, Density and Refractive Index for Heavy Metal Fluoride Glasses%重金属氟化玻璃密度、组分与折射率关系的研究

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The density and the refractive index for various compositions of heavy metal fluoride (HMF) glasses, used to make low-loss optical wave-guides, have been measured by standard archimedes method and by using as Pulfrich refractometer respectively. The density as a function of composition is calculated considering the effective volume of the ions contained in the glass to be invariant. The refractive index as a function of composition is also calculated, based on the Lorenz-Lorentz equation, by computing the electronic polarizability of HMF glasses. All calculated results are in good agreement with the observed data.

  6. Flocculation of metals during mixing of Siyahrud River water with Caspian Sea water.

    Science.gov (United States)

    Biati, Aida; Karbassi, Abdulreza R

    2012-11-01

    Flocculation of dissolved Cu, Mn, Ni, Zn, and Pb during mixing of Siyahrud River water with water sample of Caspian Sea at nine different salinity regimes was investigated. The maximum flocculation of elements occurs in the salinities 1.67‰ to 3.67‰ (except for Zn). The flocculation trend of Zn (80.9) >Mn (58.3) > Cu (30.5) > Ni (25.9) > Pb (19.5) indicates that flocculation of metals have nonlinear behavior towards salinity changes during estuarine mixing. Electrical conductivity shows a linear behavior in different proportions of salinity which is in contrast with the behavior of other studied parameters. Cluster analysis indicates that pH and NO(3) are governing factors in the flocculation of Cu, Mn, and Pb. The results of this research show that 80.9%, 19.5%, 25.9%, 30.5%, and 58.3% of dissolved Zn, Pb, Ni, Cu, and Mn flocculate during estuarine mixing. Total amount of studied dissolved element flowing in to the Caspian Sea would decrease from 5.62 to 2.76 t/year.

  7. Measured rates of fluoride/metal association correlate with rates of superoxide/metal reactions for Fe(III)EDTA(H2O)- and related complexes.

    Science.gov (United States)

    Summers, Jack S; Baker, Joseph B; Meyerstein, Dan; Mizrahi, Amir; Zilbermann, Israel; Cohen, Haim; Wilson, Christopher M; Jones, Jamie R

    2008-02-06

    The effects of 10 paramagnetic metal complexes (Fe(III)EDTA(H2O)-, Fe(III)EDTA(OH)2-, Fe(III)PDTA-, Fe(III)DTPA2-, Fe(III)2O(TTHA)2-, Fe(III)(CN)6(3-), Mn(II)EDTA(H2O)2-, Mn(II)PDTA2-, Mn(II)beta-EDDADP2-, and Mn(II)PO4(-)) on F- ion 19F NMR transverse relaxation rates (R2 = 1/T2) were studied in aqueous solutions as a function of temperature. Consistent with efficient relaxation requiring formation of a metal/F- bond, only the substitution inert complexes Fe(III)(CN)6(3-) and Fe(III)EDTA(OH)2- had no measured effect on T2 relaxation of the F- 19F resonance. For the remaining eight complexes, kinetic parameters (apparent second-order rate constants and activation enthalpies) for metal/F- association were determined from the dependence of the observed relaxation enhancements on complex concentration and temperature. Apparent metal/F- association rate constants for these complexes (k(app,F-)) spanned 5 orders of magnitude. In addition, we measured the rates at which O2*- reacts with Fe(III)PDTA-, Mn(II)EDTA(H2O)2-, Mn(II)PDTA2-, and Mn(II)beta-EDDADP2- by pulse radiolysis. Although no intermediate is observed during the reduction of Fe(III)PDTA- by O2*-, each of the Mn(II) complexes reacts with formation of a transient intermediate presumed to form via ligand exchange. These reactivity patterns are consistent with literature precedents for similar complexes. With these data, both k(app,O2-) and k(app,F-) are available for each of the eight reactive complexes. A plot of log(k(app,O2-)) versus log(k(app,F-)) for these eight showed a linear correlation with a slope approximately 1. This correlation suggests that rapid metal/O2*- reactions of these complexes occur via an inner-sphere mechanism whereas formation of an intermediate coordination complex limits the overall rate. This hypothesis is also supported by the very low rates at which the substitution inert complexes (Fe(III)(CN)6(3-) and Fe(III)EDTA(OH)2-) are reduced by O2*-. These results suggest that F- 19F NMR

  8. Mixed-Valent NaCu4Se3: A Two-Dimensional Metal.

    Science.gov (United States)

    Sturza, Mihai; Bugaris, Daniel E; Malliakas, Christos D; Han, Fei; Chung, Duck Young; Kanatzidis, Mercouri G

    2016-05-16

    The new ternary copper selenide NaCu4Se3 crystallizes in the RbCd4As3 structure type with the trigonal space group R3̅m and lattice constants a = 4.0316(4) Å and c = 31.438(8) Å. Its structure is built from two-dimensional slabs of (2)/∞[Cu4Se3] separated by Na(+) cations. The compound is formally mixed-valent with Se(2-)/Se(-) atoms and exhibits metallic properties. It is a hole conductor with an electrical conductivity of ∼300 S cm(-1) at room temperature and a thermopower of ∼10 μV K(-1). Hall effect measurements indicate holes as the dominant carrier with a concentration of ∼6.12(1) × 10(21) cm(-3) at 300 K. Density functional theory electronic structure calculations indicate p-type metallic behavior for the (2)/∞[Cu4Se3] framework, which is in a good agreement with the experimental metallic conductivity and Pauli paramagnetism.

  9. Dynamics and morphology of the Milky Way spiral arms from the metallicity distribution and radial mixing

    Science.gov (United States)

    Martinez-Medina, L. A.; Pichardo, B.; Peimbert, A.; Carigi, L.

    2017-07-01

    Albeit radial migration must be a ubiquitous process in disc galaxies, its significance in the evolution of stellar discs is not always reflected through global trends. However, there are other key observables, such as the metallicity distribution function (MDF), that may shed some light in this matter. We argue that the shape of the MDF not only tells us whether the stellar disc experienced radial migration but it also contains important clues on the structure that triggered it. Specifically, the MDF contains information about the dynamics and morphology of the spiral pattern. To constrain the spiral parameters, we have included a detailed chemical tagging in our simulations; this allows us to produce a restriction of the structural parameters of the spiral arms in the Milky Way as well as a method to constrain chemical evolution models towards the centre of the Galactic disc, where no chemical model provides information. We also found that it is unlikely that the Sun was formed near its current galactocentric position; therefore, it might be inaccurate to consider the Sun as representative of the chemical abundances in the solar neighbourhood. We also show that a stellar disc of the Milky Way, after evolving dynamically and chemically for 5 Gyr, preserves 80 per cent of its original global metallicity gradient despite having suffered important heating and radial migration; this means that the presence of a metallicity gradient in a given galaxy does not guarantee that radial mixing has not played a role in its evolution.

  10. Designing mixed metal halide ammines for ammonia storage using density functional theory and genetic algorithms.

    Science.gov (United States)

    Jensen, Peter Bjerre; Lysgaard, Steen; Quaade, Ulrich J; Vegge, Tejs

    2014-09-28

    Metal halide ammines have great potential as a future, high-density energy carrier in vehicles. So far known materials, e.g. Mg(NH3)6Cl2 and Sr(NH3)8Cl2, are not suitable for automotive, fuel cell applications, because the release of ammonia is a multi-step reaction, requiring too much heat to be supplied, making the total efficiency lower. Here, we apply density functional theory (DFT) calculations to predict new mixed metal halide ammines with improved storage capacities and the ability to release the stored ammonia in one step, at temperatures suitable for system integration with polymer electrolyte membrane fuel cells (PEMFC). We use genetic algorithms (GAs) to search for materials containing up to three different metals (alkaline-earth, 3d and 4d) and two different halides (Cl, Br and I) - almost 27,000 combinations, and have identified novel mixtures, with significantly improved storage capacities. The size of the search space and the chosen fitness function make it possible to verify that the found candidates are the best possible candidates in the search space, proving that the GA implementation is ideal for this kind of computational materials design, requiring calculations on less than two percent of the candidates to identify the global optimum.

  11. Transport of Indium, Gallium and Thallium Metal Ions Through Chromatographic Fiber Supported Solid Membrane in Acetylacetone Containing Mixed Solvents

    Institute of Scientific and Technical Information of China (English)

    Abaji Gaikwad

    2011-01-01

    The transport of metal ions of indium, gallium and thallium from source solution to receiving phase through the chromatographic fiber supported solid membrane in the acetylacetone (HAA) containing mixed solvent system has been explored. The fibers supported solid membranes were prepared with chemical synthesis from cellulose fibers and citric acid with the carboxylic acid ion exchange groups introduced. The experimental variables, such as concentration of metal ions (10^-2 to 10^-4 mol.L^-1) in the source solution, mixed solvent composition [for exampl, e, acetylacetone, (2,4-pentanedione), (HAA) 20% (by volume), 1,4-dioxane 10% to 60% and HC1 0.25 to 2 mol.L^-1] in the receiving phase and stirring speed (50-130 r.min ) of the bulk source and receiving phase, were explored. The efficiency of mixed solvents for the transport of metal ions from the source to receiving phase through the fiber supported solid membrane was evaluated. The combined ion exchange solvent extraction (CIESE) was observed effective for the selective transport of thallium, indium and gallium metal ions through fiber supported solid membrane in mixed solvents. The oxonium salt formation in the receiving phase enhances thallium, indium and gallium metal ion transport through solid membrane phase. The selective transport of thallium metal ions from source phase was observed from indium and gallium metal ions in the presence of hydrochloric acid in organic solvents in receiving phase. The separation of thallium metal ions from the binary mixtures of Be(II), Ti(IV), AI(III) Ca(II), Mg(II), K (I), La(III) and Y(III) was carried out in the mixed solvent system using cellulose fiber supported solid membrane.

  12. Rational composition control of mixed-lanthanide metal-organic frameworks by an interfacial reaction with metal ion-doped polymer substrates

    Science.gov (United States)

    Tsuruoka, Takaaki; Miyanaga, Ayumi; Ohhashi, Takashi; Hata, Manami; Takashima, Yohei; Akamatsu, Kensuke

    2017-09-01

    A simple composition control route to mixed-lanthanide metal-organic frameworks (MOFs) was developed based on an interfacial reaction with mixed-lanthanide metal ion-doped polymer substrates. By controlling the composition of lanthanide ion (Eu3+ and Tb3+) dopants in polymer substrates to be used as metal ion precursors and scaffolding for the formation of MOFs, [EuxTb2-x(bdc)3(H2O)4]n crystals with a tunable metal composition could be routinely prepared on polymer substrates. Inductively coupled plasma (ICP) measurements revealed that the composition of the obtained frameworks was almost the same as that of the initial polymer substrates. In addition, the resulting [EuxTb2-x(bdc)3(H2O)4]n crystals showed strong phosphorescence because of Eu3+ transitions, indicating that the energy transfer from Tb3+ to Eu3+ ions in the frameworks could be achieved with high efficiency.

  13. Size partitioning and mixing behavior of trace metals and dissolved organic matter in a South China estuary.

    Science.gov (United States)

    Wang, Wenhao; Chen, Min; Guo, Laodong; Wang, Wen-Xiong

    2017-12-15

    The Jiulong River estuary, located in the southeastern China, suffered from metal pollution due to industrial effluent releases. Mixing of effluent and estuarine water may have significantly affected the size distribution of trace metals and their environmental fate. In the present study, colloidal size distribution of organic matter and selected metals were quantified using asymmetric flow field-flow fractionation (AF4) and ICP-MS. We demonstrated a dominance of dissolved metals in the 1-10kDa fraction, and metals such as Cu, Zn, Ni, Co, Pb, Cd and Mn were mostly regulated by terrestrial fulvic acid. The larger inorganic colloids played a limited role, although Fe reduction was likely to affect the size partitioning of colloidal Mn. The holding pond represented a source of trace metals and chromophoric and humic-like dissolved organic matter to the estuary. Scavenging or removal behavior became evident following the intermittent mixing, and the small sized colloidal organic complexes were responsible for binding and stabilizing trace metals. Variations in particle size distributions indicated different sources, fates and geochemical controls of the metals. Our results highlighted the impacts of both natural and anthropogenic processes on the transformation of trace metals among phases in this dynamic estuary system. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Method of CO and/or CO.sub.2 hydrogenation using doped mixed-metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Shekhawat, Dushyant; Berry, David A.; Haynes, Daniel J.; Abdelsayed, Victor; Smith, Mark W.; Spivey, James J.

    2015-10-06

    A method of hydrogenation utilizing a reactant gas mixture comprising a carbon oxide and a hydrogen agent, and a hydrogenation catalyst comprising a mixed-metal oxide containing metal sites supported and/or incorporated into the lattice. The mixed-metal oxide comprises a perovskite, a pyrochlore, a fluorite, a brownmillerite, or mixtures thereof doped at the A-site or the B-site. The metal site may comprise a deposited metal, where the deposited metal is a transition metal, an alkali metal, an alkaline earth metal, or mixtures thereof. Contact between the carbon oxide, hydrogen agent, and hydrogenation catalyst under appropriate conditions of temperature, pressure and gas flow rate generate a hydrogenation reaction and produce a hydrogenated product made up of carbon from the carbon oxide and some portion of the hydrogen agent. The carbon oxide may be CO, CO.sub.2, or mixtures thereof and the hydrogen agent may be H.sub.2. In a particular embodiment, the hydrogenated product comprises an alcohol, an olefin, an aldehyde, a ketone, an ester, an oxo-product, or mixtures thereof.

  15. Method of CO and/or CO.sub.2 hydrogenation to higher hydrocarbons using doped mixed-metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Shekhawat, Dushyant; Berry, David A.; Haynes, Daniel J.; Abdelsayed, Victor; Smith, Mark W.; Spivey, James J.

    2017-03-21

    A method of hydrogenation utilizing a reactant gas mixture comprising a carbon oxide and a hydrogen agent, and a hydrogenation catalyst comprising a mixed-metal oxide containing metal sites supported and/or incorporated into the lattice. The mixed-metal oxide comprises a pyrochlore, a brownmillerite, or mixtures thereof doped at the A-site or the B-site. The metal site may comprise a deposited metal, where the deposited metal is a transition metal, an alkali metal, an alkaline earth metal, or mixtures thereof. Contact between the carbon oxide, hydrogen agent, and hydrogenation catalyst under appropriate conditions of temperature, pressure and gas flow rate generate a hydrogenation reaction and produce a hydrogenated product made up of carbon from the carbon oxide and some portion of the hydrogen agent. The carbon oxide may be CO, CO.sub.2, or mixtures thereof and the hydrogen agent may be H.sub.2. In a particular embodiment, the hydrogenated product comprises olefins, paraffins, or mixtures thereof.

  16. Fluoride glass fiber optics

    CERN Document Server

    Aggarwal, Ishwar D

    1991-01-01

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

  17. Arsenic from community water fluoridation: quantifying the effect.

    Science.gov (United States)

    Peterson, Emily; Shapiro, Howard; Li, Ye; Minnery, John G; Copes, Ray

    2016-04-01

    Community water fluoridation is a WHO recommended strategy to prevent dental carries. One debated concern is that hydrofluorosilicic acid, used to fluoridate water, contains arsenic and poses a health risk. This study was undertaken to determine if fluoridation contributes to arsenic in drinking water, to estimate the amount of additional arsenic associated with fluoridation, and compare this to the National Sanitation Foundation/American National Standards Institute (NSF/ANSI) standard and estimates from other researchers. Using surveillance data from Ontario drinking water systems, mixed effects linear regression was performed to examine the effect of fluoridation status on the difference in arsenic concentration between raw water and treated water samples. On average, drinking water treatment was found to reduce arsenic levels in water in both fluoridated and non-fluoridated systems by 0.2 μg/L. However, fluoridated systems were associated with an additional 0.078 μg/L (95% CI 0.021, 0.136) of arsenic in water when compared to non-fluoridated systems (P = 0.008) while controlling for raw water arsenic concentrations, types of treatment processes, and source water type. Our estimate is consistent with concentrations expected from other research and is less than 10% of the NSF/ANSI standard of 1 μg/L arsenic in water. This study provides further information to inform decision-making regarding community water fluoridation.

  18. The Applications of Mixed Metal Oxides to Capture the CO2 and Convert to Syn-Gas

    Directory of Open Access Journals (Sweden)

    A. G. Gaikwad

    2015-01-01

    Full Text Available AbstractThe applicationsof different mixed metal oxides were explored for the capture of CO2and convert of CO2 to syn-gas. The several samples of the mixedmetal oxides were prepared by the sol gel, solid-solid fusion, precipitation,molten salt and template methods in order to investigate the performance ofmixed mtal oxides to the CO2 applications. These samples werecalcined for the 3h in air at 900 oC. The mixed metal oxides sampleswere characterized by acidity/ basicity, surface area, XRD pattern, SEM imagesand to capture CO2. The basicity and surface area of the samples of mixedmetal oxides were found to be in the range from 0.7 to 15.7 mmol g-1and 2.24 to 138.76 m2 g-1, respectively. The obtainedresults of prepared mixed metal oxides by different method were compared forthe purpose of searching the efficient materials. The temperature profiles of thecaptured CO2 by the samples of mixed metal oxides were obtained inthe range 100 to 800 oC. The captured CO2 was found to bein the range from 7.36 to 26.93 wt%. The conversions of CO2 bymethane were explored to syn-gas over the mixed metal oxides including the calciumiron lanthanum mixed metal oxides and Pd (5 wt %/Al2O3at 700 oC with the gas hourly space velocities (GHSV 6000 ml h-1g-1 of methane, 6000 ml h-1 g-1 of CO2and 24000 ml h-1 g-1 of helium.

  19. Mode-synthesizing atomic force microscopy for volume characterization of mixed metal nanoparticles.

    Science.gov (United States)

    Vitry, P; Bourillot, E; Tétard, L; Plassard, C; Lacroute, Y; Lesniewska, E

    2016-09-01

    Atomic force microscopy (AFM) and other techniques derived from AFM have revolutionized the understanding of materials and biology at the nanoscale, but mostly provide surface properties. The observation of subsurface nanoscale features and properties remains a great challenge in nanometrology. The operating principle of the mode-synthesizing AFM (MSAFM) is based on the interaction of two ultrasonic waves, one launched by the AFM probe fp , a second launched by the sample fs , and their resulting nonlinear frequency mixing. Recent developments highlighted the need for quantitative correlation between the role of the frequency actuation of the probe fp and the sample fs . Here we present the great potential of MSAFM for advanced volume characterization of metallic nanoparticles presenting a multilayered structure composed of a nickel core surrounded by a gold envelope.

  20. Scoping evaluation of the technical capabilities of DOE sites for disposal of hazardous metals in mixed low-level waste

    Energy Technology Data Exchange (ETDEWEB)

    Gruebel, M.M.; Waters, R.D.; Langkopf, B.S.

    1997-05-01

    A team of analysts designed and conducted a scoping evaluation to estimate the technical capabilities of fifteen Department of Energy sites for disposal of the hazardous metals in mixed low-level waste (i.e., waste that contains both low-level radioactive materials and hazardous constituents). Eight hazardous metals were evaluated: arsenic, barium, cadmium, chromium, lead, mercury, selenium, and silver. The analysis considered transport only through the groundwater pathway. The results are reported as site-specific estimates of maximum concentrations of each hazardous metal in treated mixed low-level waste that do not exceed the performance measures established for the analysis. Also reported are site-specific estimates of travel times of each hazardous metal to the point of compliance.

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

    OpenAIRE

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

    2017-01-01

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

  2. Water-Air Mixing Jet Produced by Electro-hydraulic Impulse Technology Strengthening the Quality of Surface of Metal Materials

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Electro-hydraulic impulse water-air mixing jet by which the quality of metal materials can be improved is described in this paper. The experimental results proved that the hardness and the micro-hardness of the surface layer of metal materials can be improved with this method, for example, the microhardness of CrWMn can be increased by 35.62percent.

  3. Effects of Different Soil Amendments on Mixed Heavy Metals Contamination in Vetiver Grass.

    Science.gov (United States)

    Ng, Chuck Chuan; Boyce, Amru Nasrulhaq; Rahman, Md Motior; Abas, Mhd Radzi

    2016-11-01

    Three different types of low cost soil amendments, namely, EDTA, elemental S and N-fertilizer, were investigated with Vetiver grass, Vetiveria zizanioides (Linn.) Nash growing under highly mixed Cd-Pb contamination conditions. A significant increase (p < 0.05) in Cd and Pb accumulation were recorded in the shoots of all EDTA and N-fertilizer assisted treatments. The accumulation of Cd in 25 mmol EDTA/kg soil and 300 mmol N/kg soil showed relatively higher translocation factor (1.72 and 2.15) and percentage metal efficacy (63.25 % and 68.22 %), respectively, compared to other treatments. However, it was observed that the increased application of elemental S may inhibit the availability of Pb translocation from soil-to-root and root-to-shoot. The study suggests that viable application of 25 mmol EDTA/kg, 300 mmol N/kg and 20 mmol S/kg soil have the potential to be used for soil amendment with Vetiver grass growing under contaminated mixed Cd-Pb soil conditions.

  4. Selective oxidation of propane to acrylic acid over mixed metal oxide catalysts

    Institute of Scientific and Technical Information of China (English)

    Wei Zheng; Zhenxing Yu; Ping Zhang; Yuhang Zhang; Hongying Fu; Xiaoli Zhang; Qiquan Sun; Xinguo Hu

    2008-01-01

    The effects of metal atomic ratio, water content, oxygen content, and calcination temperature on the catalytic perfor-mances of MoVTeNbO mixed oxide catalyst system for the selective oxidation of propane to acrylic acid have been investigated and discussed. Among the catalysts studied, it was found that the MoVTeNbO catalyst calcined at a temperature of 600 ℃ showed the best performance in terms of propane conversion and selectivity for acrylic acid under an atmosphere of nitrogen. An effective MoVTeNbO oxide catalyst for propane selective oxidation to acrylic acid was obtained with a combination of a preferred metal atomic ratio (Mo1 V0.31Te0.23Nb0.12). The optimum reaction condition for the selective oxidation of propane was the molar ratio of C3H81 :O2 : H2O : N1 = 4.4 : 12.8 : 15.3 : 36.9. Under such conditions, the conversion of propane and the maximum yield of acrylic acid reached about 50% and 21%, respectively.

  5. Aqueous batteries based on mixed monovalence metal ions: a new battery family.

    Science.gov (United States)

    Chen, Liang; Zhang, Leyuan; Zhou, Xufeng; Liu, Zhaoping

    2014-08-01

    As existing battery technologies struggle to meet the requirements for widespread use in the field of large-scale energy storage, new concepts are urgently needed to build batteries with high energy density, low cost, and good safety. Here, we demonstrate two new aqueous batteries based on two monovalence metal ions (Li(+) /K(+) and Na(+) /K(+) ) as charge-transfer ions, Ni1 Zn1 HCF/TiP2 O7 and Ni1 Zn1 HCF/NaTi2 (PO4 )3 . These new batteries are unlike the conventional "rocking-chair" aqueous metal-ion batteries based on the migration of one type of shuttle ion between cathode and anode. They can deliver specific energy of 46 Wh kg(-1) and 53 Wh kg(-1) based on the total mass of active materials; this is superior to current aqueous battery systems based on sodium-ion and/or potassium-ion technologies. These two new batteries together with the previously developed Li(+) /Na(+) mixed-ion battery not only constitute a new battery family for energy storage, but also greatly broaden our horizons for battery research.

  6. Light alkane (mixed feed selective dehydrogenation using bi-metallic zeolite supported catalyst

    Directory of Open Access Journals (Sweden)

    Zeeshan Nawaz

    2009-12-01

    Full Text Available Light alkanes are the important intermediates of many refinery processes and their catalytic dehydrogenation gives corresponding alkenes. The aim behind this experimentation is to investigate reaction behavior of mixed alkanes during direct catalytic dehydrogenation and emphasis has been given to enhance propene. Bi-metallic zeolite supported catalyst Pt-Sn/ZSM-5 was prepared by sequentional impregnation method and characterized by BET, EDS and XRD. Direct dehydrogenation reaction is highly endothermic and its conversion is thermodynamically limited. Results showed that the increase in temperature increases the conversion to some extent but there is no overall effect on selectivity of propene. Increase in time-on-stream (TOS remarkably improves propene selectivity at the expense of lower conversion. The performances of bi-metallic zeolite based catalyst largely affected by coke deposition. The presence of butane and ethane adversely affected propane conversion. Optimum propene selectivity is about 48 %, obtained at 600 oC and time-on-stream 10 h.

  7. Electrolytic trichloroethene degradation using mixed metal oxide coated titanium mesh electrodes.

    Science.gov (United States)

    Petersen, Matthew A; Sale, Thomas C; Reardon, Kenneth F

    2007-04-01

    Electrochemical systems provide a low cost, versatile, and controllable platform to potentially treat contaminants in water, including chlorinated solvents. Relative to bare metal or noble metal amended materials, dimensionally stable electrode materials such as mixed metal oxide coated titanium (Ti/MMO) have advantages in terms of stability and cost, important factors for sustainable remediation solutions. Here, we report the use of Ti/MMO as an effective cathode substrate for treatment of trichloroethene (TCE). TCE degradation in a batch reactor was measured as the decrease of TCE concentration over time and the corresponding evolution of chloride; notably, this occurred without the formation of commonly encountered chlorinated intermediates. The reaction was initiated when Ti/MMO cathode potentials were less than -0.8 V vs. the standard hydrogen electrode, and the rate of TCE degradation increased linearly with progressively more negative potentials. The maximum pseudo-first-order heterogeneous rate constant was approximately 0.05 cm min(-1), which is comparable to more commonly used cathode materials such as nickel. In laboratory-scale flow-though column reactors designed to simulate permeable reactive barriers (PRBs), TCE concentrations were reduced by 80-90%. The extent of TCE flux reduction increased with the applied potential difference across the electrodes and was largely insensitive to the spacing distance between the electrodes. This is the first report of the electrochemical reduction of a chlorinated organic contaminant at a Ti/MMO cathode, and these results support the use of this material in PRBs as a possible approach to manage TCE plume migration.

  8. Fluoride and lead adsorption on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    WANG Shuguang; LI Yanhui

    2004-01-01

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

  9. Fluoride toothpastes and fluoride mouthrinses for home use

    OpenAIRE

    Andrew Rugg-Gunn; Jolan Bánóczy

    2013-01-01

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

  10. Gas transport in metal organic framework–polyetherimide mixed matrix membranes: The role of the polyetherimide backbone structure

    NARCIS (Netherlands)

    Hegde, Maruti; Shahid, S.; Norder, Ben; Dingemans, Theo J.; Nijmeijer, Dorothea C.

    2015-01-01

    We report on how the morphology of the polymer matrix, i.e. amorphous vs. semi-crystalline, affects the gas transport properties in a series of mixed matrix membranes (MMMs) using Cu3(BTC)2 as the metal organic framework (MOF) filler. The aim of our work is to demonstrate how incorporation of

  11. General synthesis of vanadium-based mixed metal oxides hollow nanofibers for high performance lithium-ion batteries

    Science.gov (United States)

    Xiang, Juan; Yu, Xin-Yao; Paik, Ungyu

    2016-10-01

    Hollow nanostructured mixed metal oxides have recently been intensively investigated as electrode materials for energy storage and conversion due to their remarkable electrochemical properties. Although great efforts have been made, the synthesis of hollow nanostructured vanadium-based mixed metal oxides especially those with one dimensional structure is rarely reported. Vanadium-based mixed metal oxides are promising electrode materials for lithium-ion batteries with high capacity and good rate capability. Here, we develop a facile and general method for the synthesis of one dimensional MxV2O8 (M = Co, Ni, Fe) tubular structure through a simple single-spinneret electrospinning technique followed by a calcination process. As a demonstration, Co3V2O8 hollow nanofibers are evaluated as anode materials for lithium-ion batteries. As expected, benefiting from their unique one dimensional tubular structure, the as-synthesized Co3V2O8 exhibits excellent electrochemical properties for lithium storage. To be specific, it can deliver a high specific capacity of 900 mAh g-1 at 5 A g-1, and long cycling stability up to 2000 cycles. The present work makes a significant contribution to the design and synthesis of mixed metal oxides with one dimensional tubular structure, as well as their potential applications in electrochemical energy storage.

  12. Gas transport in metal organic framework–polyetherimide mixed matrix membranes: The role of the polyetherimide backbone structure

    NARCIS (Netherlands)

    Hegde, Maruti; Shahid, Salman; Norder, Ben; Dingemans, Theo J.; Nijmeijer, Kitty

    2015-01-01

    We report on how the morphology of the polymer matrix, i.e. amorphous vs. semi-crystalline, affects the gas transport properties in a series of mixed matrix membranes (MMMs) using Cu3(BTC)2 as the metal organic framework (MOF) filler. The aim of our work is to demonstrate how incorporation of Cu3(BT

  13. Fluoride and Oral Health.

    Science.gov (United States)

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

    2016-06-01

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

  14. Preparation of a durable superhydrophobic membrane by electrospinning poly (vinylidene fluoride) (PVDF) mixed with epoxy-siloxane modified SiO2 nanoparticles: a possible route to superhydrophobic surfaces with low water sliding angle and high water contact angle.

    Science.gov (United States)

    Wang, Shuai; Li, Yapeng; Fei, Xiaoliang; Sun, Mingda; Zhang, Chaoqun; Li, Yaoxian; Yang, Qingbiao; Hong, Xia

    2011-07-15

    A durable superhydrophobic surface with low water sliding angle (SA) and high water contact angle (CA) was obtained by electrospinning poly (vinylidene fluoride) (PVDF) which was mixed with epoxy-siloxane modified SiO(2) nanoparticles. To increase the roughness, modified SiO(2) nanoparticles were introduced into PVDF precursor solution. Then in the electrospinning process, nano-sized SiO(2) particles irregularly inlayed (it could also be regard as self-assembly) in the surface of the micro-sized PVDF mini-islands so as to form a dual-scale structure. This structure was responsible for the superhydrophobicity and self-cleaning property. In addition, epoxy-siloxane copolymer was used to modify the surface of SiO(2) nanoparticles so that the SiO(2) nanoparticles could stick to the surface of the micro-sized PVDF mini-islands. Through the underwater immersion test, the SiO(2) nanoparticles cannot be separated from PVDF easily so as to achieve the effect of durability. We chiefly explore the surface wettability and the relationship between the mass ratio of modified SiO(2) nanoparticles/PVDF and the CA, SA of electrospun mat. As the content of modified SiO(2) nanoparticles increased, the value of CA increased, ranging from 145.6° to 161.2°, and the water SA decreased to 2.17°, apparently indicating that the membrane we fabricated has a perfect effect of superhydrophobicity.

  15. Mixed-Metal Strategy on Metal-Organic Frameworks (MOFs) for Functionalities Expansion: Co Substitution Induces Aerobic Oxidation of Cyclohexene over Inactive Ni-MOF-74.

    Science.gov (United States)

    Sun, Dengrong; Sun, Fangxiang; Deng, Xiaoyu; Li, Zhaohui

    2015-09-08

    Different amounts of Co-substituted Ni-MOF-74 have been prepared via a post-synthetic metal exchange. Inductively coupled plasma mass spectrometry, powder X-ray diffraction (XRD), N2 adsorption/desorption, and extended X-ray absorption fine structure (EXAFS) analyses indicated the successful metathesis between Co and Ni in Ni-MOF-74 to form the solid-solution-like mixed-metal Co/Ni-MOF-74. It was found that introduction of active Co into the Ni-MOF-74 framework enabled the inert Ni-MOF-74 to show activity for cyclohexene oxidation. Since Co was favorably substituted at positions more accessible to the substrate, the mixed-metal Co/Ni-MOF-74 showed superior catalytic performance, compared with pure Co-MOF-74 containing a similar amount of Co. This study provides a facile method to develop solid-solution-like MOFs for heterogeneous catalysis and highlights the great potential of this mixed-metal strategy in the development of MOFs with specific endowed functionalities.

  16. Process for removing and detoxifying cadmium from scrap metal including mixed waste

    Energy Technology Data Exchange (ETDEWEB)

    Kronberg, J.W.

    1994-07-01

    Cadmium-bearing scrap from nuclear applications, such as neutron shielding and reactor control and safety rods, must usually be handled as mixed waste since it is radioactive and the cadmium in it is both leachable and highly toxic. Removing the cadmium from this scrap, and converting it to a nonleachable and minimally radioactive form, would greatly simplify disposal or recycling. A process now under development will do this by shredding the scrap; leaching it with reagents which selectively dissolve out the cadmium; reprecipitating the cadmium as its highly insoluble sulfide; then fusing the sulfide into a glassy matrix to bring its leachability below EPA limits before disposal. Alternatively, the cadmium may be recovered for reuse. A particular advantage of the process is that all reagents (except the glass frit) can easily be recovered and reused in a nearly closed cycle, minimizing the risk of radioactive release. The process does not harm common metals such as aluminum, iron and stainless steel, and is also applicable to non-nuclear cadmium-bearing scrap such as nickel-cadmium batteries.

  17. Study of mixed ternary transition metal ferrites as potential electrodes for supercapacitor applications

    Science.gov (United States)

    Bhujun, Bhamini; Tan, Michelle T. T.; Shanmugam, Anandan S.

    Nanocrystallites of three mixed ternary transition metal ferrite (MTTMF) were prepared by a facile sol-gel method and adopted as electrode material for supercapacitors. The phase development of the samples was determined using Fourier transform infrared (FT-IR) and thermal gravimetric analysis (TG). X-ray diffraction (XRD) analysis revealed the formation of a single-phase spinel ferrite in CuCoFe2O4 (CuCoF), NiCoFe2O4 (NiCoF) and NiCuFe2O4 (NiCuF). The surface characteristics and elemental composition of the nanocomposites have been studied by means of field emission scanning electron microscopy (FESEM), as well as energy dispersive spectroscopy (EDS). The electrochemical performance of the nanomaterials was evaluated using a two-electrode configuration by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic technique in 1 M KOH electrolyte and was found to be in the order of: CuCoF > NiCoF > NiCuF. A maximum specific capacitance of 221 Fg-1 was obtained with CuCoF at a scan rate of 5 mV s-1. In addition to an excellent cycling stability, an energy density of 7.9 kW kg-1 was obtained at a current density of 1 Ag-1. The high electrochemical performance of the MTTMF nanocomposites obtained indicates that these materials are promising electrodes for supercapacitors.

  18. Thermally induced growth of ZnO nanocrystals on mixed metal oxide surfaces.

    Science.gov (United States)

    Inayat, Alexandra; Makky, Ayman; Giraldo, Jose; Kuhnt, Andreas; Busse, Corinna; Schwieger, Wilhelm

    2014-06-23

    An in situ method for the growth of ZnO nanocrystals on Zn/Al mixed metal oxide (MMO) surfaces is presented. The key to this method is the thermal treatment of Zn/Al layered double hydroxides (Zn/Al LDHs) in the presence of nitrate anions, which results in partial demixing of the LDH/MMO structure and the subsequent crystallization of ZnO crystals on the surface of the forming MMO layers. In a first experimental series, thermal treatment of Zn/Al LDHs with different fractions of nitrate and carbonate in the interlayer space was examined by thermogravimetry coupled with mass spectrometry (TG-MS) and in situ XRD. In a second experimental series, Zn/Al LDHs with only carbonate in the interlayer space were thermally treated in the presence of different amounts of an external nitrate source (NH4NO3). All obtained Zn/Al MMO samples were analysed by electron microscopy, nitrogen physisorption and powder X-ray diffraction. The gas phase formed during nitrate decomposition turned out to be responsible for the formation of crystalline ZnO nanoparticles. Accordingly, both interlayer nitrate and the presence of ammonium nitrate led to the formation of supported ZnO nanocrystals with mean diameters between 100 and 400 nm, and both methods offer the possibility to tailor the amount and size of the ZnO crystals by means of the amount of nitrate.

  19. Fluoride Rinses, Gels and Foams

    DEFF Research Database (Denmark)

    Twetman, Svante; Keller, Mette K

    2016-01-01

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

  20. Fluorides and non-fluoride remineralization systems.

    Science.gov (United States)

    Amaechi, Bennett T; van Loveren, Cor

    2013-01-01

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

  1. Structural influence of mixed transition metal ions on lithium bismuth borate glasses

    Science.gov (United States)

    Yadav, Arti; Dahiya, Manjeet S.; Hooda, A.; Chand, Prem; Khasa, S.

    2017-08-01

    Lithium bismuth borate glasses containing mixed transition metals having composition 7CoO·23Li2O·20Bi2O3·50B2O3 (CLBB), 7V2O5·23Li2O·20Bi2O3·50B2O3 (VLBB) and x(2CoO·V2O5)·(30 - x)Li2O·20Bi2O3·50B2O3 (x = 0.0 (LBB) and x = 2.0, 5.0, 7.0, 10.0 mol% (CVLBB1-4)) are synthesized via melt quench route. The synthesized compositions are investigated for their physical properties using density (D) and molar volume (Vm), thermal properties by analyzing DSC/TG thermo-graphs, structural properties using IR absorption spectra in the mid-IR range and optical properties using UV-Vis-NIR spectroscopy. The Electron Paramagnetic Resonance (EPR) spectra of vanadyl and cobalt ion have been analyzed to study compositional effects on spin-Hamiltonian parameters. The non linear variations in physical properties depict a strong structural influence of Co/V- oxides on the glassy matrix. The compositional variations in characteristic temperatures (glass transition temperature Tg, glass crystallization temperature Tp and glass melting temperature Tm) reveals that Tg for glass samples CLBB is relatively less than that of pure lithium bismuth borate (LBB) glass sample wherein Tg for sample VLBB is higher than that of LBB. The increase in Tg (as compared with LBB) with an enhanced substitution of mixed transition metal oxides (2CoO·V2O5) shows a progressive structure modification of bismuth borate matrix. These predictions are very well corroborated by corresponding compositional trends of Tp and Tm. FTIR studies reveal that Co2+& VO2+ ions lead to structural rearrangements through the conversion of three-coordinated boron into four coordinated boron and thereby reducing number of non-bridging oxygen atoms. Bismuth is found to exist in [BiO6] octahedral units only, whereas boroxol rings are not present in the glass network. The theoretical values of optical basicity (Λth) and corresponding oxide ion polarizability (αo2-) have also been calculated to investigate oxygen covalency of

  2. PRODUCTION OF THORIUM FLUORIDE

    Science.gov (United States)

    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.

  3. Ternary mixed metal Fe-doped NiCo2O4 nanowires as efficient electrocatalysts for oxygen evolution reaction

    Science.gov (United States)

    Yan, Kai-Li; Shang, Xiao; Li, Zhen; Dong, Bin; Li, Xiao; Gao, Wen-Kun; Chi, Jing-Qi; Chai, Yong-Ming; Liu, Chen-Guang

    2017-09-01

    Designing mixed metal oxides with unique nanostructures as efficient electrocatalysts for water electrolysis has been an attractive approach for the storage of renewable energies. The ternary mixed metal spinel oxides FexNi1-xCo2O4 (x = 0, 0.1, 0.25, 0.5, 0.75, 0.9, 1) have been synthesized by a facile hydrothermal approach and calcination treatment using nickel foam as substrate. Fe/Ni ratios have been proved to affect the nanostructures of FexNi1-xCo2O, which imply different intrinsic activity for oxygen evolution reaction (OER). SEM images show that Fe0.5Ni0.5Co2O4 has the uniform nanowires morphology with about 30 nm of the diameter and 200-300 nm of the length. The OER measurements show that Fe0.5Ni0.5Co2O4 exhibits the better electrocatalytic performances with lower overpotential of 350 mV at J = 10 mA cm-2. In addition, the smaller Tafel slope of 27 mV dec-1 than other samples with different Fe/Ni ratios for Fe0.5Ni0.5Co2O4 is obtained. The improved OER activity of Fe0.5Ni0.5Co2O4 may be attributed to the synergistic effects from ternary mixed metals especially Fe-doping and the uniform nanowires supported on NF. Therefore, synthesizing Fe-doped multi-metal oxides with novel nanostructures may be a promising strategy for excellent OER electrocatalysts and it also provides a facile way for the fabrication of high-activity ternary mixed metal oxides electrocatalysts.

  4. Turbulent mixing of metal and silicate during planet accretion — And interpretation of the Hf-W chronometer

    Science.gov (United States)

    Dahl, Tais W.; Stevenson, David J.

    2010-06-01

    In the current view of planet formation, the final assembly of the Earth involved giant collisions between proto-planets (> 1000 km radius), with the Moon formed as a result of one such impact. At this stage the colliding bodies had likely differentiated into a metallic core surrounded by a silicate mantle. During the Moon-forming impact, nearly all metal sank into the Earth's core. We investigate to what extent large self-gravitating iron cores can mix with surrounding silicate and how this influences the short-lived chronometer, Hf-W, used to infer the age of the Moon. We present fluid dynamical models of turbulent mixing in fully liquid systems, attempting to place constraints on the degree of mixing. Erosion of sinking cores driven by Rayleigh-Taylor instability does lead to intimate mixing and equilibration, but large blobs (> 10 km diameter) do not emulsify entirely. Emulsification is enhanced if most of the accreting metal cores deform into thin structures during descent through the Earth's mantle. Yet, only 1-20% of Earth's core would equilibrate with silicate during Earth's accretion. The initial speed of the impactor is of little importance. We proceed to evaluate the mixing potential for shear instabilities where silicate entrainment across vertical walls causes mixing. The turbulent structure indicates that vortices remain at the largest scale and do not mix to centimeter length scale, where diffusion operates and isotopes can equilibrate. Thus, incomplete emulsification and equilibration of accreting iron cores is likely to occur. The extent of metal-silicate equilibration provides key information for interpretation of siderophile budgets and the timing of core formation using the Hf-W chronometer. The time scale of core formation derived from the Hf-W chronometer is usually tied to the last major metal-silicate re-equilibration, believed to coincide with time of the Moon-forming impact. However, we show that large cores have limited ability to reset

  5. Turbulent mixing of metal and silicate during planet accretion — And interpretation of the Hf–W chronometer

    OpenAIRE

    Dahl, Tais W.; Stevenson, David J.

    2010-01-01

    In the current view of planet formation, the final assembly of the Earth involved giant collisions between proto-planets (> 1000 km radius), with the Moon formed as a result of one such impact. At this stage the colliding bodies had likely differentiated into a metallic core surrounded by a silicate mantle. During the Moon-forming impact, nearly all metal sank into the Earth's core. We investigate to what extent large self-gravitating iron cores can mix with surrounding silicate and how this ...

  6. Influence of Anthropogenic Contamination on Fluoride Concentration in Groundwater

    Directory of Open Access Journals (Sweden)

    SUDHAKAR M. RAO

    2012-06-01

    Full Text Available Groundwater Contamination is a serious concern in India. Major geogenic contaminants include fluoride, arsenic and iron, while common anthropogenic contaminants include nitrate, metals, organic and microbial contamination. Besides, known point and diffuse sources, groundwater contamination from infiltration of pit toilet leachate is an emerging concern. The study area of this paper is Kolar district in Karnataka that is hot spot of fluoride contamination. The absence of fluoride contamination in Mulbagal town and the alterations in groundwater chemistry from infiltration of pit toilet leachate motivated the author to examine the possible linkages between anthropogenic contamination and fluoride concentration in groundwater of Mulbagal town. Analysis of the groundwater chemistry revealed that the groundwater in Mulbagal town is under saturated with respect to calcite that suppresses the disolution of fluorite and the fluoride concentration in the groundwater. The slightly acidic pH of the groundwater is considered responsible to facilitate calcite dissolution under saturation.

  7. Fluoride varnishes and enamel caries

    NARCIS (Netherlands)

    Bruyn, Hugo de

    1987-01-01

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

  8. Fluoride varnishes and enamel caries

    NARCIS (Netherlands)

    Bruyn, Hugo de

    1987-01-01

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

  9. Heterogeneous Partial (ammOxidation and Oxidative Dehydrogenation Catalysis on Mixed Metal Oxides

    Directory of Open Access Journals (Sweden)

    Jacques C. Védrine

    2016-01-01

    Full Text Available This paper presents an overview of heterogeneous partial (ammoxidation and oxidative dehydrogenation (ODH of hydrocarbons. The review has been voluntarily restricted to metal oxide-type catalysts, as the partial oxidation field is very broad and the number of catalysts is quite high. The main factors of solid catalysts for such reactions, designated by Grasselli as the “seven pillars”, and playing a determining role in catalytic properties, are considered to be, namely: isolation of active sites (known to be composed of ensembles of atoms, Me–O bond strength, crystalline structure, redox features, phase cooperation, multi-functionality and the nature of the surface oxygen species. Other important features and physical and chemical properties of solid catalysts, more or less related to the seven pillars, are also emphasized, including reaction sensitivity to metal oxide structure, epitaxial contact between an active phase and a second phase or its support, synergy effect between several phases, acid-base aspects, electron transfer ability, catalyst preparation and activation and reaction atmospheres, etc. Some examples are presented to illustrate the importance of these key factors. They include light alkanes (C1–C4 oxidation, ethane oxidation to ethylene and acetic acid on MoVTe(SbNb-O and Nb doped NiO, propene oxidation to acrolein on BiMoCoFe-O systems, propane (ammoxidation to (acrylonitrile acrylic acid on MoVTe(SbNb-O mixed oxides, butane oxidation to maleic anhydride on VPO: (VO2P2O7-based catalyst, and isobutyric acid ODH to methacrylic acid on Fe hydroxyl phosphates. It is shown that active sites are composed of ensembles of atoms whose size and chemical composition depend on the reactants to be transformed (their chemical and size features and the reaction mechanism, often of Mars and van Krevelen type. An important aspect is the fact that surface composition and surface crystalline structure vary with reaction on stream until

  10. Analysis of porosity characteristics in weld metal of high strength aluminum alloy and the effect of mixed shielding gas

    Energy Technology Data Exchange (ETDEWEB)

    Xiaomu Zhang; Zhiyong Zhang; Yun Peng; Zhiling Tian; Changhong He; Hongjun Xiao; Chengyong Ma [Central Iron and Steel Research Inst., Beijing, BJ (China)

    2005-07-01

    Aluminum alloy has being widely used in modern automobile and aeronautic industry. However, the welding of aluminum alloy, especially high strength aluminum alloy is difficult. Porosities are usually brought in the weld metal. In this paper, MIG welding using mixed gas shielding is carried out. The characteristic shapes of porosity in weld metal are described, the mechanism of porosity formation is analyzed, and the factors that influence the tendency of porosity formation are studied. Experiment results indicate that by the use of mixed shielding gas of 38%He+62%Ar, the number of porosity is reduced, the width of HAZ and softened zone is decreased, and the mechanical properties of welded joint is increased. (orig.)

  11. Solvent-Free Selective Oxidation of Toluene with O2 Catalyzed by Metal Cation Modified LDHs and Mixed Oxides

    Directory of Open Access Journals (Sweden)

    Xiaoli Wang

    2016-01-01

    Full Text Available A series of metal cation modified layered-double hydroxides (LDHs and mixed oxides were prepared and used to be the selective oxidation of toluene with O2. The results revealed that the modified LDHs exhibited much higher catalytic performance than their parent LDH and the modified mixed oxides. Moreover, the metal cations were also found to play important roles in the catalytic performance and stabilities of modified catalysts. Under the optimal reaction conditions, the highest toluene conversion reached 8.7% with 97.5% of the selectivity to benzyldehyde; moreover, the catalytic performance remained after nine catalytic runs. In addition, the reaction probably involved a free-radical mechanism.

  12. Dual Electrospray Pyrolysis for Mixed Metal Oxide (and Carbon) Composite Nanoparticle Synthesis with Applications in Energy Storage

    Science.gov (United States)

    Tang, Justin; Liu, Wen; Wang, Hailiang; Gomez, Alessandro

    We present a novel approach to synthesizing mixed metal oxide nanoparticles with a continuous, scalable aerosol flow process using the electrospray. The electrospray is a liquid atomization technique that generates a monodisperse population of highly charged liquid droplets over a broad size range (nanometric to tens of microns). Each liquid droplet serves as a micro-reactor, containing a payload of suitable precursors (such as metal nitrides), allowing for precise control over particle composition and size. By using two electrosprays of opposite polarities, the two highly charged droplets plumes are electrostatically mixed to produce a charge-neutral aerosol. Electrostatically driven droplet-droplet collisions can also be used to control morphology to some degree. This aerosol is passed through a tubular furnace via carrier gas, pyrolizing the precursors to synthesize nanomaterials. We apply this approach to manganese oxide, cobalt oxide, and carbon composite nanoparticles for use in energy storage applications.

  13. Precursor combustion synthesis of nanocrystalline cobalt substituted nickel zinc ferrites from hydrazinated mixed metal fumarates

    Energy Technology Data Exchange (ETDEWEB)

    Gawas, S.G.; Verenkar, V.M.S., E-mail: vmsv@rediffmail.com

    2015-04-10

    Highlights: • Convenient synthesis of hydrazinated mixed metal fumarates under nitrogen atmosphere. • Six hydrazine molecules in precursor provide high exothermicity for the decomposition. • Autocatalytic decomposition of precursors helps in ferritization at 410 °C. • Single domain-superparamagnetic particles of uniform size in the range of 15–30 nm. - Abstract: In present investigation, a systematic approach towards synthesis of nanocrystalline ferrites, Co{sub x}Ni{sub 0.6−x}Zn{sub 0.4}Fe{sub 2}O{sub 4} (x = 0.1 and 0.4) has been reported by room temperature decomposition of precursors, Co{sub x}Ni{sub 0.6−x}Zn{sub 0.4}Fe{sub 2} (C{sub 4}H{sub 2}O{sub 4}){sub 3}·6N{sub 2}H{sub 4} (x = 0.1 and 0.4). The precursor complexes were characterized by Fourier transform infrared spectroscopy (FTIR), chemical analysis and thermal studies like isothermal mass loss, total mass loss, thermogravimetry (TG), derivative of thermogravimetry (DTG) and differential thermal analysis (DTA). The TG–DTG–DTA patterns of both precursors reveal multistep decomposition with complete ferritization at 410 °C. The thermally decomposed products were characterized by X-ray diffractometry (XRD) for phase purity. The FT-IR spectroscopy studies of the same shows complete removal of all organic moieties from decomposed precursors. The nanophasic nature of synthesized ferrites was confirmed by transmission electron microscopy (TEM) analysis as well as from broadening of XRD peaks. The AC magnetization studies show the existence of single domain and superparamagnetic particles, which supports nanosize particles distribution in the ferrite system under study.

  14. Parametric Investigation of Powder Mixed Electrical Discharge Machining of Al-Sic Metal Matrix Composites

    Directory of Open Access Journals (Sweden)

    R. K. Arya

    2012-12-01

    Full Text Available Abstract – In recent few years composite materials have gained pace in engineering application. But they have poor machinability by using conventional machining methods. So it is required to study about these materials for better use in engineering application. To fulfillment of this aim, a study is done by conduct experiments (i.e. Machining on Al/SiC metal matrix composite (MMC. From the non-conventional machining process, Powder Mixed Electrical discharge machining (PMEDM is used to machining of Al/SiC MMC. PMEDM is a technological improvement in conventional EDM, which was previously studied by many researchers to better MRR with good surface roughness (SR. In this study, the controllable machining process parameters (i.e. Peak Current (Ip, Duty Cycle, Powder Concentration (PC, Gap Control and Sensitivity of PMEDM was selected to experimental investigation. The process performance is measured in terms of material removal rate (MRR and surface finish (SR. The research outcome will identify the important parameters and their effect on MRR of Al/SiC MMC in the presence of suspended graphite (Gr powder in a kerosene dielectric of EDM. Response surface methodology (RSM has been used to plan and analyze the experimental results. The experimental results emerged that only sensitivity has non-significant effect on MMR and SR from the selected process parameters, but it gives significant effects with other factors in interaction. Further it found that, the MRR is directly proportional to Ip and inversely proportional to the PC and duty cycle, and the SR improves at lower Ip and optimum range of PC, gap control and duty cycle.

  15. Slow relaxation of the magnetization in non-linear optical active layered mixed metal oxalate chains.

    Science.gov (United States)

    Cariati, Elena; Ugo, Renato; Santoro, Giuseppe; Tordin, Elisa; Sorace, Lorenzo; Caneschi, Andrea; Sironi, Angelo; Macchi, Piero; Casati, Nicola

    2010-12-06

    New Co(II) members of the family of multifunctional materials of general formula [DAMS](4)[M(2)Co(C(2)O(4))(6)]·2DAMBA·2H(2)O (M(III) = Rh, Fe, Cr; DAMBA = para-dimethylaminobenzaldehyde and [DAMS(+)] = trans-4-(4-dimethylaminostyryl)-1-methylpyridinium) have been isolated and characterized. Such new hybrid mixed metal oxalates are isostructural with the previously investigated containing Zn(II), Mn(II), and Ni(II). This allows to preserve the exceptional second harmonic generation (SHG) activity, due to both the large molecular quadratic hyperpolarizability of [DAMS(+)] and the efficiency of the crystalline network which organizes [DAMS(+)] into head-to-tail arranged J-type aggregates, and to further tune the magnetic properties. In particular, the magnetic data of the Rh(III) derivative demonstrate that high spin octacoordinated Co(II) centers behave very similarly to the hexacoordinated Co(II) ones, being dominated by a large orbital contribution. The Cr(III) derivative is characterized by ferromagnetic Cr(III)-Co(II) interactions. Most relevantly, the Fe(III) compound is characterized by a moderate antiferromagnetic interaction between Fe(III) and Co(II), resulting in a ferrimagnetic like structure. Its low temperature dynamic magnetic properties were found to follow a thermally activated behavior (τ(0) = 8.6 × 10(-11) s and ΔE = 21.4 K) and make this a candidate for the second oxalate-based single chain magnet (SCM) reported up to date, a property which in this case is coupled to the second order non linear optical (NLO) ones.

  16. Sensitive Photoacoustic IR Spectroscopy for the Characterization of Amino/Azido Mixed-Linker Metal-Organic Frameworks.

    Science.gov (United States)

    Canivet, Jerome; Lysenko, Vladimir; Lehtinen, Jaakko; Legrand, Alexandre; Wisser, Florian M; Quadrelli, Elsje Alessandra; Farrusseng, David

    2017-08-23

    Photoacoustic Fourier-transform infrared spectroscopy makes it possible to determine the organic composition of mixed-linker metal-organic frameworks. The sound produced upon IR irradiation enables the discrimination of azido and amino linkers in three different MOF platforms with a sensitivity that is two orders of magnitude higher than that achieved using classic IR analysis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Salt fluoridation and oral health

    OpenAIRE

    Thomas M. Marthaler

    2013-01-01

    The aim of this paper is to make known the potential of fluoridated salt in community oral health programs, particularly in South Eastern Europe. Since 1922, the addition of iodine to salt has been successful in Switzerland. Goiter is virtually extinct. By 1945, the cariesprotective effect of fluorides was well established. Based on the success of water fluoridation, a gynecologist started adding of fluoride to salt. The sale of fluoridated salt began in 1956 in the Swiss Canton of Zurich,...

  18. The cariostatic mechanisms of fluoride

    OpenAIRE

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

    2013-01-01

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

  19. Porous ZnCo 2 O 4 nanoparticles derived from a new mixed-metal organic framework for supercapacitors

    KAUST Repository

    Chen, Siru

    2015-01-01

    Cobalt-based oxides have been shown to be promising materials for application in high-energy-density Li-ion batteries and supercapacitors. In this paper, we report a new and simple strategy for the synthesis of a mixed-metal spinel phase (ZnCo2O4) from a zinc and cobalt mixed-metal organic framework (JUC-155). It is important to rationally design a MOF with a precise ratio (Co/Zn) and a synthetic process that is simple and time saving. After solid-state annealing of the mixed-metal MOF precursor at 400 °C for two hours, a pure ZnCo2O4 phase with a high surface area (55 cm2 g−1) was obtained. When used as electrode materials for supercapacitors, an exceptionally high specific capacitance of 451 F g−1 was obtained at the scan rate of 5 mV s−1. The capacitance loss after 1500 cycles was only 2.1% at a current density of 2 A g−1, indicating that this phase has an excellent cycling stability. These remarkable electrochemical performances suggest that this phase is potentially promising for application as an efficient electrode in electrochemical capacitors.

  20. Colloid formation and metal transport through two mixing zones affected by acid mine drainage near Silverton, Colorado

    Science.gov (United States)

    Schemel, L.E.; Kimball, B.A.; Bencala, K.E.

    2000-01-01

    Stream discharges and concentrations of dissolved and colloidal metals (Al, Ca, Cu, Fe, Mg, Mn, Pb, and Zn), SO4, and dissolved silica were measured to identify chemical transformations and determine mass transports through two mixing zones in the Animas River that receive the inflows from Cement and Mineral Creeks. The creeks were the dominant sources of Al, Cu, Fe, and Pb, whereas the upstream Animas River supplied about half of the Zn. With the exception of Fe, which was present in dissolved and colloidal forms, the metals were dissolved in the acidic, high-SO4 waters of Cement Creek (pH 3.8). Mixing of Cement Creek with the Animas River increased pH to near-neutral values and transformed Al and some additional Fe into colloids which also contained Cu and Pb. Aluminium and Fe colloids had already formed in the mildly acidic conditions in Mineral Creek (pH 6.6) upstream of the confluence with the Animas River. Colloidal Fe continued to form downstream of both mixing zones. The Fe- and Al-rich colloids were important for transport of Cu, Pb, and Zn, which appeared to have sorbed to them. Partitioning of Zn between dissolved and colloidal phases was dependent on pH and colloid concentration. Mass balances showed conservative transports for Ca, Mg, Mn, SO4, and dissolved silica through the two mixing zones and small losses (< 10%) of colloidal Al, Fe and Zn from the water column.

  1. Effects of calcination temperature and acid-base properties on mixed potential ammonia sensors modified by metal oxides.

    Science.gov (United States)

    Satsuma, Atsushi; Katagiri, Makoto; Kakimoto, Shiro; Sugaya, Satoshi; Shimizu, Kenichi

    2011-01-01

    Mixed potential sensors were fabriated using yttria-stabilized zirconia (YSZ) as a solid electrolyte and a mixture of Au and various metal oxides as a sensing electrode. The effects of calcination temperature ranging from 600 to 1,000 °C and acid-base properties of the metal oxides on the sensing properties were examined. The selective sensing of ammonia was achieved by modification of the sensing electrode using MoO(3), Bi(2)O(3) and V(2)O(5), while the use of WO(3,) Nb(2)O(5) and MgO was not effective. The melting points of the former group were below 820 °C, while those of the latter group were higher than 1,000 °C. Among the former group, the selective sensing of ammonia was strongly dependent on the calcination temperature, which was optimum around melting point of the corresponding metal oxides. The good spreading of the metal oxides on the electrode is suggested to be one of the important factors. In the former group, the relative response of ammonia to propene was in the order of MoO(3) > Bi(2)O(3) > V(2)O(5), which agreed well with the acidity of the metal oxides. The importance of the acidic properties of metal oxides for ammonia sensing was clarified.

  2. Effects of Calcination Temperature and Acid-Base Properties on Mixed Potential Ammonia Sensors Modified by Metal Oxides

    Directory of Open Access Journals (Sweden)

    Kenichi Shimizu

    2011-02-01

    Full Text Available Mixed potential sensors were fabriated using yttria-stabilized zirconia (YSZ as a solid electrolyte and a mixture of Au and various metal oxides as a sensing electrode. The effects of calcination temperature ranging from 600 to 1,000 °C and acid-base properties of the metal oxides on the sensing properties were examined. The selective sensing of ammonia was achieved by modification of the sensing electrode using MoO3, Bi2O3 and V2O5, while the use of WO3, Nb2O5 and MgO was not effective. The melting points of the former group were below 820 °C, while those of the latter group were higher than 1,000 °C. Among the former group, the selective sensing of ammonia was strongly dependent on the calcination temperature, which was optimum around melting point of the corresponding metal oxides. The good spreading of the metal oxides on the electrode is suggested to be one of the important factors. In the former group, the relative response of ammonia to propene was in the order of MoO3 > Bi2O3 > V2O5, which agreed well with the acidity of the metal oxides. The importance of the acidic properties of metal oxides for ammonia sensing was clarified.

  3. Effects of Calcination Temperature and Acid-Base Properties on Mixed Potential Ammonia Sensors Modified by Metal Oxides

    Science.gov (United States)

    Satsuma, Atsushi; Katagiri, Makoto; Kakimoto, Shiro; Sugaya, Satoshi; Shimizu, Kenichi

    2011-01-01

    Mixed potential sensors were fabriated using yttria-stabilized zirconia (YSZ) as a solid electrolyte and a mixture of Au and various metal oxides as a sensing electrode. The effects of calcination temperature ranging from 600 to 1,000 °C and acid-base properties of the metal oxides on the sensing properties were examined. The selective sensing of ammonia was achieved by modification of the sensing electrode using MoO3, Bi2O3 and V2O5, while the use of WO3, Nb2O5 and MgO was not effective. The melting points of the former group were below 820 °C, while those of the latter group were higher than 1,000 °C. Among the former group, the selective sensing of ammonia was strongly dependent on the calcination temperature, which was optimum around melting point of the corresponding metal oxides. The good spreading of the metal oxides on the electrode is suggested to be one of the important factors. In the former group, the relative response of ammonia to propene was in the order of MoO3 > Bi2O3 > V2O5, which agreed well with the acidity of the metal oxides. The importance of the acidic properties of metal oxides for ammonia sensing was clarified. PMID:22319402

  4. Impacts of a Flaring Star-forming Disc and Stellar Radial Mixing on the Vertical Metallicity Gradient

    CERN Document Server

    Kawata, D; Gibson, B K; Casagrande, L; Hunt, J A S; Brook, C B

    2016-01-01

    Using idealised N-body simulations of a Milky Way-sized disc galaxy, we qualitatively study how the metallicity distributions of the thin disc stars, are modified by the formation of the bar and spiral arm structures. The thin disc of our numerical experiments initially has a tight negative radial metallicity gradient, and a constant vertical scale-height. We show that the radial mixing of stars drives a positive vertical metallicity gradient in the thin disc. On the other hand, if the initial thin disc is flaring, with vertical scale-height increasing with galactocentric radius, the metal poor stars originally in the outer disc become dominant in regions above the disc plane at every radii. This process can drive a negative vertical metallicity gradient, which is consistent with the current observed trend. This model mimics a scenario where the star-forming thin disc was flaring in the outer region at earlier epochs. Our numerical experiments predict that the negative vertical metallicity gradient of the mon...

  5. 45%苯醚·硫酰氟熏蒸剂现场灭蟑药效试验研究%Field test of the biological efficacy of the 45% mixed fumigant of sulfuryl fluoride with d-Cyphenothrin on cockroach control

    Institute of Scientific and Technical Information of China (English)

    黄清臻; 贾瑞忠; 杨振洲; 李彦; 韩华; 石华; 孙成祥; 毛桂宜

    2012-01-01

    Objective To observe the killing efficacy of the 45% mixed fumigant of sulfuryl fluoride with d - Cyphenothrin on cockroaches. Methods The 45% mixed fumigant of sulfuryl fluoride with d - Cyphenothrin was applied at 10-20 g/m3 in the kitchen operating area of a hotel restaurant and the change in the cockroach density was observed. Results The cockroach mortality rate was 88.04%-100% within 6-72 h after application of the mixed fumigant at 10-20 g/m3, with an average decrease of 82.46%-98.53% in the cockroach density 72 hours after the application of the fumigant. Conclusion The 45% mixed fumigant of sulfuryl fluoride with d-Cyphenothrin can be used to kill cockroaches in confined spaces.%目的 观察45%苯醚·硫酰氟熏蒸剂现场熏蒸灭蟑效果.方法 选择宾馆餐厅的操作间施用45%苯醚·硫酰氟熏蒸剂10~20 g/m3,观察72 h蜚蠊密度变化.结果 45%苯醚·硫酰氟熏蒸剂现场使用10~20 g/m3时,标示性蜚蠊6~72 h死亡率为88.04%~100%,处理后72 h蜚蠊密度平均下降率为82.46%~98.53%.结论 45%苯醚·硫酰氟熏蒸剂可用于密闭场所灭蟑.

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    the levels with and without parallel use of fluoride toothpaste. DESIGN: Fifteen healthy children were enrolled to a randomized crossover trial that was performed in two parts: Part I with twice-daily tooth brushing with fluoride toothpaste and Part II with twice-daily brushing with a non-fluoride toothpaste......: There was a statistically significant increase in the 6-h fluoride excretion after application of both experimental varnishes, with and without parallel use of fluoride toothpaste (P toothpaste was used, the mean fluoride excretion was 0.20 mg/6 h after application of Duraphat and 0.29 mg/6 h...... after application of Profluorid Varnish (P = 0.18). CONCLUSIONS: Topical applications of 0.1 mL of fluoride varnish significantly increased the 6-h fluoride excretion. As some individuals displayed excretion levels exceeding the optimal fluoride exposure, a restricted use of fluoride toothpaste...

  7. Mn 3+ stabilization in complex phosphate-fluoride fluxes and its incorporation into langbeinite framework

    Science.gov (United States)

    Ogorodnyk, Ivan V.; Zatovsky, Igor V.; Baumer, Vyacheslav N.; Slobodyanik, Nikolay S.; Shishkin, Oleg V.; Vorona, Igor P.

    2007-10-01

    Two new mixed valence manganese-containing orthophosphates with a langbeinite structure have been obtained from the complex fluoride-phosphate melts using the high-temperature flux technique. MIVF 4 and K 2MIVF 6 ( MIV—Zr, Hf) were used as fluoride and polyvalent metal precursors. Obtained langbeinites were investigated using a single-crystal X-ray diffraction, FTIR-, UV-VIS- and electron paramagnetic resonance (EPR)-spectroscopy. Both compounds crystallize in a cubic system (sp. gr. P2 13) with cell parameters a=10.2106(12) and 10.1896(9) Å for K 1.96Mn 0.57Zr 1.43(PO 4) 3 and K 1.93Mn 0.53Hf 1.47(PO 4) 3, respectively. The rigid langbeinite-like framework is built up from the isolated [MO 6] octahedra and [PO 4] tetrahedra interlinked via oxygen vertices. Potassium cations occupy positions in the large closed cavities of the framework. Statistical distribution of manganese and tetravalent metal over two crystallographic positions in octahedral oxygen environment can be observed. The presence of the mixed valence manganese in the reported phosphates was confirmed using UV-VIS and EPR-spectroscopy.

  8. Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles

    Directory of Open Access Journals (Sweden)

    Timothy A. DeVol

    2010-03-01

    Full Text Available This paper reviews the synthesis, structure and applications of metal fluoride nanoparticles, with particular focus on rare earth (RE doped fluoride nanoparticles obtained by our research group. Nanoparticles were produced by precipitation methods using the ligand ammonium di-n-octadecyldithiophosphate (ADDP that allows the growth of shells around a core particle while simultaneously avoiding particle aggregation. Nanoparticles were characterized on their structure, morphology, and luminescent properties. We discuss the synthesis, properties, and application of heavy metal fluorides; specifically LaF3:RE and PbF2, and group IIA fluorides. Particular attention is given to the synthesis of core/shell nanoparticles, including selectively RE-doped LaF3/LaF3, and CaF2/CaF2 core/(multi-shell nanoparticles, and the CaF2-LaF3 system.

  9. Microbiological-enhanced mixing across scales during in-situ bioreduction of metals and radionuclides at Department of Energy Sites

    Energy Technology Data Exchange (ETDEWEB)

    Valocchi, Albert [Univ. of Illinois, Urbana-Champaign, IL (United States); Werth, Charles [Univ. of Texas, Austin, TX (United States); Liu, Wen-Tso [Univ. of Illinois, Urbana-Champaign, IL (United States); Sanford, Robert [Univ. of Illinois, Urbana-Champaign, IL (United States); Nakshatrala, Kalyan [Univ. of Houston, TX (United States)

    2015-10-20

    Bioreduction is being actively investigated as an effective strategy for subsurface remediation and long-term management of DOE sites contaminated by metals and radionuclides (i.e. U(VI)). These strategies require manipulation of the subsurface, usually through injection of chemicals (e.g., electron donor) which mix at varying scales with the contaminant to stimulate metal reducing bacteria. There is evidence from DOE field experiments suggesting that mixing limitations of substrates at all scales may affect biological growth and activity for U(VI) reduction. Although current conceptual models hold that biomass growth and reduction activity is limited by physical mixing processes, a growing body of literature suggests that reaction could be enhanced by cell-to-cell interaction occurring over length scales extending tens to thousands of microns. Our project investigated two potential mechanisms of enhanced electron transfer. The first is the formation of single- or multiple-species biofilms that transport electrons via direct electrical connection such as conductive pili (i.e. ‘nanowires’) through biofilms to where the electron acceptor is available. The second is through diffusion of electron carriers from syntrophic bacteria to dissimilatory metal reducing bacteria (DMRB). The specific objectives of this work are (i) to quantify the extent and rate that electrons are transported between microorganisms in physical mixing zones between an electron donor and electron acceptor (e.g. U(IV)), (ii) to quantify the extent that biomass growth and reaction are enhanced by interspecies electron transport, and (iii) to integrate mixing across scales (e.g., microscopic scale of electron transfer and macroscopic scale of diffusion) in an integrated numerical model to quantify these mechanisms on overall U(VI) reduction rates. We tested these hypotheses with five tasks that integrate microbiological experiments, unique micro-fluidics experiments, flow cell experiments, and

  10. Analysis of micro vortex metallization and introduction of evaluation factor in mixing process

    Institute of Scientific and Technical Information of China (English)

    HE Jun-guo; WEI Xi-zhu; JIANG Tao; ZHANG Jie

    2009-01-01

    To improve the mixing efficiency in water purification or wastewater treatment process and understand the mechanism of mass transfer, and a suitable evaluation factor is introduced to evaluate the efficiency of mixing process. The diffusion mass transfer under turbulent condition is investigated based on dynamic and mathematical analysis. The results indicate that submicroscopic diffusion is the rate-limiting step in mass transfer,and the inertia effect of micro vortex causes the phase mixing. An excellent efficiency can be obtained by controlling the scale of micro vortex within millimeter. Furthermore, a new indicator named mixing factor (IH) is proposed to evaluate the efficiency of mixing processes, which is more feasible than conventional evaluation methods, because of its connection of mixing extent with energy consumption.

  11. Fluoridation: strategies for success.

    Science.gov (United States)

    Isman, R

    1981-07-01

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

  12. Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles

    OpenAIRE

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

    2010-01-01

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

  13. Unprecedented 1D Mixed-metal Polynuclear Cyclometalated Platinum Complexes: Synthesis,Structural Characterization and Spectroscopic Properties

    Institute of Scientific and Technical Information of China (English)

    CAO Qian-Yong; GAN Xin; ZHANG Jun-Feng; CHI Shao-Ming; LI Hui-Fangjie; FU Wen-Fu

    2007-01-01

    The complexes [Pt2L2(μ-dppm)](ClO4)2.(1) and {[Pt2L2(μ-dppm)Li(CH3CN)2](ClO4)3}n (2),where HL is 6-[4-(diethoxyphosphorylmethyl)phenyl]-2,2'-bipyridinyl and dppm is bis(diphenylphosphino)methane,have been synthesized and characterized.In complex 1 the platinum(Ⅱ) center adopts a distorted square planar coordination geometry.The polymer 2 exhibits a "stairstep" configuration with one-dimensional Pt(Ⅱ)N^N^CPO- Li(Ⅰ)-OPC^N^NPt(Ⅱ) mixed-metal units which are linked through dppm.Both complexes have metal-metal interaction with PtPt distances of 3.325(2) and 3.1432(9) (A),respectively,and display strong metal-metal-to-ligand charge-transfer (MMLCT) triplet state emission.The density-functional-theory calculation was used to interpret the absorption spectra of the complexes.

  14. Synthesis of reagents for fluoride technologies

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

  15. Processing of solid solution, mixed uranium/refractory metal carbides for advanced space nuclear power and propulsion systems

    Science.gov (United States)

    Knight, Travis Warren

    Nuclear thermal propulsion (NTP) and space nuclear power are two enabling technologies for the manned exploration of space and the development of research outposts in space and on other planets such as Mars. Advanced carbide nuclear fuels have been proposed for application in space nuclear power and propulsion systems. This study examined the processing technologies and optimal parameters necessary to fabricate samples of single phase, solid solution, mixed uranium/refractory metal carbides. In particular, the pseudo-ternary carbide, UC-ZrC-NbC, system was examined with uranium metal mole fractions of 5% and 10% and corresponding uranium densities of 0.8 to 1.8 gU/cc. Efforts were directed to those methods that could produce simple geometry fuel elements or wafers such as those used to fabricate a Square Lattice Honeycomb (SLHC) fuel element and reactor core. Methods of cold uniaxial pressing, sintering by induction heating, and hot pressing by self-resistance heating were investigated. Solid solution, high density (low porosity) samples greater than 95% TD were processed by cold pressing at 150 MPa and sintering above 2600 K for times longer than 90 min. Some impurity oxide phases were noted in some samples attributed to residual gases in the furnace during processing. Also, some samples noted secondary phases of carbon and UC2 due to some hyperstoichiometric powder mixtures having carbon-to-metal ratios greater than one. In all, 33 mixed carbide samples were processed and analyzed with half bearing uranium as ternary carbides of UC-ZrC-NbC. Scanning electron microscopy, x-ray diffraction, and density measurements were used to characterize samples. Samples were processed from powders of the refractory mono-carbides and UC/UC 2 or from powders of uranium hydride (UH3), graphite, and refractory metal carbides to produce hypostoichiometric mixed carbides. Samples processed from the constituent carbide powders and sintered at temperatures above the melting point of UC

  16. Sustainable approach for recycling waste lamb and chicken bones for fluoride removal from water followed by reusing fluoride-bearing waste in concrete.

    Science.gov (United States)

    Ismail, Zainab Z; AbdelKareem, Hala N

    2015-11-01

    Sustainable management of waste materials is an attractive approach for modern societies. In this study, recycling of raw waste lamb and chicken bones for defluoridation of water has been estimated. The effects of several experimental parameters including contact time, pH, bone dose, fluoride initial concentration, bone grains size, agitation rate, and the effect of co-existing anions in actual samples of wastewater were studied for fluoride removal from aqueous solutions. Results indicated excellent fluoride removal efficiency up to 99.4% and 99.8% using lamb and chicken bones, respectively at fluoride initial concentration of 10 mg F/L and 120 min contact time. Maximum fluoride uptake was obtained at neutral pH range 6-7. Fluoride removal kinetic was well described by the pseudo-second order kinetic model. Both, Langmuir and Freundlich isotherm models could fit the experimental data well with correlation coefficient values >0.99 suggesting favorable conditions of the process. Furthermore, for complete sustainable management of waste bones, the resulted fluoride-bearing sludge was reused in concrete mixes to partially replace sand. Tests of the mechanical properties of fluoride sludge-modified concrete mixes indicated a potential environmentally friendly approach to dispose fluoride sludge in concrete and simultaneously enhance concrete properties.

  17. Water Fluoridation Statistics - Percent of PWS population receiving fluoridated water

    Data.gov (United States)

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

  18. Water Fluoridation Statistics - Percent of PWS population receiving fluoridated water

    Data.gov (United States)

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

  19. Water Fluoridation Statistics - Percent of PWS population receiving fluoridated water

    Data.gov (United States)

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

  20. Fluoride glasses: properties, technology and applications

    OpenAIRE

    Poulain, M.

    2010-01-01

    Heavy Metal Fluoride Glasses (HMFG) make a group of specialty glasses that require a dry processing, purity control of starting materials and specific thermal procedures. Numerous glass compositions have been identified in different chemical systems: fluorozirconates, fluoroaluminates and fluoroindates. The most commonly used HMFG is the ZBLAN fluorozirconate glass that exhibits the largest stability against devitrification. By comparison to ZBLAN the IR cut-off wavelength is shorter in AlF3-...

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

    Science.gov (United States)

    Nordbö, H; Eriksen, H M

    1976-11-01

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

  2. Synthesis of complex fluorides for optical applications

    Science.gov (United States)

    Stepleton, Seth Eugene

    Large single crystals of alkali metal fluorides are desirable for many reasons. Fluoride laser crystals have a wide transmission range and on account of their low phonon energies, many efficient laser emissions have been obtained from 285 nm to 4.34 microm.1,2 Inorganic fluoride single crystals feature large bandgaps, very wide optical transmittance ranges from vacuum-ultraviolet (VUV) to mid-IR wavelength regions, lower refractive indices than those of oxides, and typically lower phonon energies (which drastically reduce multiphonon relaxation rates of rare earth ions).3 The main goal of this work was to investigate the hydrothermal synthesis of alkali metal fluorides. Melt techniques have been used thoroughly to research a variety of fluoride systems and showed many phases that were inaccessible due to incongruent melting or phase stability. The existence of these phases was shown but never characterized or grown as a crystalline material. Solution growth in supercritical water was an ideal way to attempt the synthesis of novel compounds and phases. New synthetic routes to known phases and compounds also arose as a part of this work. Optically clear colorless crystals of K2BeF4 were synthesized up to 2 mm in size, and showed no phase transitions up to 1029 K, which suggests paraelectricitys at room temperature, contradicting previous reports.4 Attempts to incorporate a rare earth ion into the fluoroberyllate lattice proved unsuccessful however reactions between beryllium fluoride and lanthanide fluorides could be exploited as a synthetic route to single crystal rare earth fluorides. Hydrothermal reactions with KF produced crystals of three different phases: hexagonal KY2F7, trigonal KYF4 and orthorhombic K2YF5. All were optically clear, colorless crystals, with the K2YF5 crystals growing the largest. This compound is beneficial due to its application as a radiation dosimeter and laser host. 5,6 Optical quality colorless crystals of RbY2F7 and CsY2F7 up to 4 mm in

  3. Synthesis and characterization of amine-functionalized mixed-ligand metal-organic frameworks of UiO-66 topology.

    Science.gov (United States)

    Chavan, Sachin M; Shearer, Greig C; Svelle, Stian; Olsbye, Unni; Bonino, Francesca; Ethiraj, Jayashree; Lillerud, Karl Petter; Bordiga, Silvia

    2014-09-15

    A series of amine-functionalized mixed-linker metal-organic frameworks (MOFs) of idealized structural formula Zr6O4(OH)4(BDC)(6-6X)(ABDC)6X (where BDC = benzene-1,4-dicarboxylic acid, ABDC = 2-aminobenzene-1,4-dicarboxylic acid) has been prepared by solvothermal synthesis. The materials have been characterized by thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), and Fourier transform infrared (FTIR) spectroscopy with the aim of elucidating the effect that varying the degrees of amine functionalization has on the stability (thermal and chemical) and porosity of the framework. This work includes the first application of ultraviolet-visible light (UV-vis) spectroscopy in the quantification of ABDC in mixed-linker MOFs.

  4. New organic-inorganic hybrid compounds constructed from polyoxometalates and transition metal mixed-organic-ligand complexes.

    Science.gov (United States)

    Hu, Yang-Yang; Zhang, Ting-Ting; Zhang, Xiao; Zhao, De-Chuan; Cui, Xiao-Bing; Huo, Qi-Sheng; Xu, Ji-Qing

    2016-02-14

    Five new organic-inorganic hybrid compounds based on different polyoxoanions [HxGeW12O40](n-) or [H3As2W18O62](3-) (x = 0, 2; n = 4, 2), namely [Cu3(2,2'-bpy)3(inic)(OH)(H2O)][GeW12O40]·1.5H2O (1), [Cu2(phen)2(μ2-Cl)2(inic)]2[H2GeW12O40]·2H2O (2), [Cu2(phen)2(μ2-Cl)Cl(nic)]2[H2GeW12O40] (3), [Cu2(2,2'-bpy)2(hnic)Cl]2[H2GeW12O40] (4), [Cu(phen)(inic)H2O][Cu2(phen)2(inic)2(H2O)][H3As2W18O62]·3H2O (5) (inic = isonicotinic acid, nic = nicotinic acid, hnic = 2-hydroxy-nicotinic acid, 2,2'-bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline), have been synthesized and characterized by IR, UV-Vis, XRD, cyclic voltammetric measurements and single crystal X-ray diffraction analysis. Single crystal X-ray analysis reveals that compound 1 is isomorphous and isostructural with a compound reported by us recently, the main difference between the two is the heteroatom of the polyoxoanions in the two compounds. Compound 2 is a supramolecular structure constructed from polyoxoanions and transition metal mixed-organic-ligand complexes. Compound 3 is a novel polyoxoanion bi-supported transition metal mixed-organic-ligand complex. Compound 4 is a 1-D chain structure constructed from polyoxoanions and transition metal mixed-organic-ligand complexes. The photodegradation properties of compounds 1-5 have been analyzed.

  5. Turbulent Mixing of Metal and Silicate during Planet Accretion – and interpretation of the Hf-W chronometer

    DEFF Research Database (Denmark)

    Dahl, Tais Wittchen; Stevenson, David

    2010-01-01

    to the last major metal–silicate re-equilibration, believed to coincide with time of the Moon-forming impact. However, we show that large cores have limited ability to reset the Hf–W systemin the silicate Earth. Excess 182W in bulk silicate Earth is more sensitive to early core formation processes than......In the current view of planet formation, the final assembly of the Earth involved giant collisions between protoplanets (N1000 kmradius), with theMoon formed as a result of one such impact.At this stage the colliding bodies had likely differentiated into a metallic core surrounded by a silicate...... mantle. During the Moon-forming impact, nearly all metal sank into the Earth's core. Weinvestigate towhat extent large self-gravitating iron cores can mix with surrounding silicate and howthis influences the short-lived chronometer, Hf–W, used to infer the age of the Moon. We present fluid dynamical...

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

    Science.gov (United States)

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

    2017-01-20

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

  7. Removal of mixed heavy metal ions in wastewater by zeolite 4A and residual products from recycled coal fly ash.

    Science.gov (United States)

    Hui, K S; Chao, C Y H; Kot, S C

    2005-12-09

    The removal performance and the selectivity sequence of mixed metal ions (Co(2+), Cr(3+), Cu(2+), Zn(2+) and Ni(2+)) in aqueous solution were investigated by adsorption process on pure and chamfered-edge zeolite 4A prepared from coal fly ash (CFA), commercial grade zeolite 4A and the residual products recycled from CFA. The pure zeolite 4A (prepared from CFA) was synthesized under a novel temperature step-change method with reduced synthesis time. Batch method was employed to study the influential parameters such as initial metal ions concentration, adsorbent dose, contact time and initial pH of the solution on the adsorption process. The experimental data were well fitted by the pseudo-second-order kinetics model (for Co(2+), Cr(3+), Cu(2+) and Zn(2+) ions) and the pseudo-first-order kinetics model (for Ni(2+) ions). The equilibrium data were well fitted by the Langmuir model and showed the affinity order: Cu(2+) > Cr(3+) > Zn(2+) > Co(2+) > Ni(2+) (CFA prepared and commercial grade zeolite 4A). The adsorption process was found to be pH and concentration dependent. The sorption rate and sorption capacity of metal ions could be significantly improved by increasing pH value. The removal mechanism of metal ions was by adsorption and ion exchange processes. Compared to commercial grade zeolite 4A, the CFA prepared adsorbents could be alternative materials for the treatment of wastewater.

  8. Optical detection of sodium salts of fluoride, acetate and phosphate by a diacylhydrazine ligand by the formation of a colour alkali metal complex

    Indian Academy of Sciences (India)

    Purnandhu Bose; Ranjan Dutta; I Ravikumar; Pradyut Ghosh

    2011-11-01

    A solution of N, N'-diacylhydrazine ligand in organic solvent is potential for colourimetric detection of F−/AcO−/PO$^{3−}_{4}$ via -NH deprotonation, tautomerization and its stabilization as a colour alkali metal complex.

  9. Fluoride retention by kaolin clay

    DEFF Research Database (Denmark)

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

    1997-01-01

    To evaluate the potential effectiveness of kaolin clay liners in storage of fluoride contaminated waste, an experimental study of the sorption and desorption behaviour of fluoride in kaolin clay was conducted. The degree of fluoride sorption by kaolin was found to depend on solution p...

  10. Fluoride Rinses, Gels and Foams

    DEFF Research Database (Denmark)

    Twetman, Svante; Keller, Mette K

    2016-01-01

    AIM: The aim of this conference paper was to systematically review the quality of evidence and summarize the findings of clinical trials published after 2002 using fluoride mouth rinses, fluoride gels or foams for the prevention of dental caries. METHODS: Relevant papers were selected after an el...... brushing with fluoride toothpaste....

  11. Fluoride resistance in Streptococcus mutans

    NARCIS (Netherlands)

    Liao, Ying

    2017-01-01

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

  12. Enhanced extraction of heavy metals in the two-step process with the mixed culture of Lactobacillus bulgaricus and Streptococcus thermophilus.

    Science.gov (United States)

    Chang, Young-Cheol; Choi, DuBok; Kikuchi, Shintaro

    2012-01-01

    For biological extraction of heavy metals from chromated copper arsenate (CCA) treated wood, different bacteria were investigated. The extraction rates of heavy metals using Lactobacillusbulgaricus and Streptococcusthermophilus were highest. The chemical extraction rates were depended on the amounts of pyruvic acid and lactic acid. Especially, the extraction rates using mixed pyruvic acid and lactic acid were increased compared to those of sole one. They were also enhanced in the mixed culture of L. bulgaricus and S. thermophilus. To improve the extraction of CCA, a two-step processing procedure with the mixed culture of L. bulgaricus and S. thermophilus was conducted. A maximum of 93% of copper, 86.5% of chromium, and 97.8% of arsenic were extracted after 4 days. These results suggest that a two-step process with the mixed culture of L. bulgaricus and S. thermophilus is most effective to extract heavy metals from CCA treated wood. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Monitoring of fluoride in water samples using a smartphone

    Energy Technology Data Exchange (ETDEWEB)

    Levin, Saurabh [Akvo Foundation (Netherlands); Krishnan, Sunderrajan [INREM Foundation (India); Rajkumar, Samuel; Halery, Nischal; Balkunde, Pradeep [Akvo Foundation (Netherlands)

    2016-05-01

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

  14. Relationships of human plasma fluoride and bone fluoride to age

    Energy Technology Data Exchange (ETDEWEB)

    Parkins, F.M.; Tinanoff, N.; Moutinho, M.; Anstey, M.B.; Waziri, M.H.

    1976-04-01

    There is evidence that fluoride levels in plasma correlate with the fluoride content in bones. The authors determined whether or not fluoride in plasma and bones might correlate with age. In 41 in-patients at the University Hospital, Iowa City, 36 of whom had been residing in fluoridated communities plasma fluoride was determined in the fasting stage by the fluoride ion selective electrode. The teeth of these children were compared with those of a neighboring city where the natural fluoride content in drinking water was 0.1 ppm. For the second sampling 42 months following the beginning of the program only 10 and 11 year old children - who had been 6 and 7 years old at the beginning of the experiment - were selected. Twenty-five boys and girls in each group were compared with a similar group of children as controls. After 28 months (approximately 33 rinsing with sodium fluoride solution) the DMF index in the fluoride-treated children was 18.4% less than in the controls. In the second group among 10 and 11 year old children after 42 months with 55 rinsings the difference was 35.0%. The author acknowledged that factors other than applications of sodium fluoride may have contributed to the prevention of caries in the fluoride-treated groups.

  15. Fluoride release from fluoride varnishes under acidic conditions.

    Science.gov (United States)

    Lippert, F

    2014-01-01

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

  16. Fluoride adsorption on goethite in relation to different types of surface sites

    NARCIS (Netherlands)

    Hiemstra, T.; Riemsdijk, van W.H.

    2000-01-01

    Metal (hydr)oxides have different types of surface groups. Fluoride ions have been used as a probe to assess the number of surface sites. We have studied the F− adsorption on goethite by measuring the F− and H interaction and F− adsorption isotherms. Fluoride ions exchange against singly coordinated

  17. Mixed polyvalent-monovalent metal coating for carbon-graphite fibers

    Science.gov (United States)

    Harper-Tervet, J.; Tervet, F. W.; Humphrey, M. F. (Inventor)

    1982-01-01

    An improved coating of gasification catalyst for carbon-graphite fibers is provided comprising a mixture of a polyvalent metal such as calcium and a monovalent metal such as lithium. The addition of lithium provides a lighter coating and a more flexible coating when applied to a coating of a carboxyl containing resin such as polyacrylic acid since it reduces the crosslink density. Furthermore, the presence of lithium provides a glass-like substance during combustion which holds the fiber together resulting in slow, even combustion with much reduced evolution of conductive fragments. The coated fibers are utilized as fiber reinforcement for composites.

  18. Solubility of hydrogen and its isotopes in metals from mixed gases

    Science.gov (United States)

    San Marchi, C.; Somerday, B. P.; Larson, R. S.; Rice, S. F.

    2008-01-01

    This short communication reviews the classical thermodynamics governing dissolution of hydrogen in metals. Classical thermodynamics is then applied to equilibrium dissolution of hydrogen and its isotopes in metals from mixtures of their diatomic gases. For simplicity in presentation, we use the specific example of H 2 and D 2 gas mixtures to demonstrate the general principles of equilibrium solubility; however, other systems may be treated analogously. The formation of HD gas is shown to have a significant effect on equilibrium solubility since it affects the chemical potentials of the H 2 and D 2 gases. Finally, we compare this thermodynamic analysis with empirical solutions from the literature.

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

    Science.gov (United States)

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

    2016-11-01

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

  20. Enthalpies of mixing in binary liquid alloys of lutetium with 3d metals

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Michael; Berezutski, Vadim [National Academy of Sciences, Kyiv (Ukraine). I. Frantsevich Institute for Problems of Materials Science; Usenko, Natalia; Kotova, Natalia [Taras Shevchenko National Univ., Kyiv (Ukraine). Dept. of Chemistry

    2017-01-15

    The enthalpies of mixing in binary liquid alloys of lutetium with chromium, cobalt, nickel and copper were determined at 1 773 - 1 947 K by isoperibolic calorimetry. The enthalpies of mixing in the Lu-Cr melts (measured up to 40 at.% Cr) demonstrate endothermic effects (ΔH = 6.88 ± 0.66 kJ . mol{sup -1} at x{sub Lu} = 0.60), whereas significant exothermic enthalpies of mixing have been established within a wide composition region for the Co-Lu, Ni-Lu and Cu-Lu liquid alloys. Minimum values of the integral enthalpy of mixing are as follows: ΔH{sub min} = -23.57 ± 1.41 kJ . mol{sup -1} at x{sub Lu} = 0.38 for the Co-Lu system; ΔH{sub min} = -48.65 ± 2.83 kJ . mol{sup -1} at x{sub Lu} = 0.40 for the Ni-Lu system; ΔH{sub min} = -24.63 ± 1.52 kJ . mol{sup -1} at x{sub Lu} = 0.37 for the Cu-Lu system.

  1. 40 CFR 721.10148 - Acryloxy alkanoic alkane derivative with mixed metal oxides (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Acryloxy alkanoic alkane derivative... Significant New Uses for Specific Chemical Substances § 721.10148 Acryloxy alkanoic alkane derivative with...) The chemical substance identified generically as acryloxy alkanoic alkane derivative with mixed...

  2. A metal ion charged mixed matrix membrane for selective adsorption of hemoglobin

    NARCIS (Netherlands)

    Tetala, K.K.R.; Skrzypek, K.; Levisson, M.; Stamatialis, D.F.

    2013-01-01

    In this work, we developed a mixed matrix membrane by incorporating 20–40 µm size iminodiacetic acid modified immobeads within porous Ethylene vinyl alcohol (EVAL) polymer matrix. The MMM were charged with copper ions for selective adsorption of bovine hemoglobin in presence of bovine serum albumin.

  3. Recovery of protactinium from molten fluoride nuclear fuel compositions

    Science.gov (United States)

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

    1973-12-25

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

  4. Redox Dynamics of Mixed Metal (Mn, Cr, and Fe) Ultrafine Particles

    Energy Technology Data Exchange (ETDEWEB)

    Nico, Peter S.; Kumfer, Benjamin M.; Kennedy, Ian M.; Anastasio, Cort

    2008-08-01

    The impact of particle composition on metal oxidation state, and on changes in oxidation state with simulated atmospheric aging, are investigated experimentally in flame-generated nanoparticles containing Mn, Cr, and Fe. The results demonstrate that the initial fraction of Cr(VI) within the particles decreases with increasing total metal concentration in the flame. In contrast, the initial Mn oxidation state was only partly controlled by metal loading, suggesting the importance of other factors. Two reaction pathways, one reductive and one oxidative, were found to be operating simultaneously during simulated atmospheric aging. The oxidative pathway depended upon the presence of simulated sunlight and O{sub 3}, whereas the reductive pathway occurred in the presence of simulated sunlight alone. The reductive pathway appears to be rapid but transient, allowing the oxidative pathway to dominate with longer aging times, i.e. greater than {approx}8 hours. The presence of Mn within the particles enhanced the importance of the oxidative pathway, leading to more net Cr oxidation during aging implying that Mn can mediate oxidation by removal of electrons from other particulate metals.

  5. Mono- and Dinuclear Macrocyclic Calcium Complexes as Platforms for Mixed-Metal Complexes and Clusters.

    Science.gov (United States)

    Connolly, Emma A; Leeland, James W; Love, Jason B

    2016-01-19

    Mono- and dinuclear calcium complexes of the Schiff-base macrocycles H4L have been prepared and characterized spectroscopically and crystallographically. In the formation of Ca(THF)2(H2L(1)), Ca2(THF)2(μ-THF)(L(1)), and Ca2(THF)4(L(2)), the ligand framework adopts a bowl-shaped conformation instead of the conventional wedge, Pacman-shaped structure as seen with the anthracenyl-hinged complex Ca2(py)5(L(3)). The mononuclear calcium complex Ca(THF)2(H2L(1)) reacts with various equivalents of LiN(SiMe3)2 to form calcium/alkali metal clusters and dinuclear transition metal complexes when reacted subsequently with transition metal salts. The dinuclear calcium complex Ca2(THF)2(μ-THF)(L(1)), when reacted with various equivalents of NaOH, is shown to act as a platform for the formation of calcium/alkali metal hydroxide clusters, displaying alternate wedged and bowl-shaped conformations.

  6. Study on treatment of wastewater containing fluoride and heavy metals by chemical coagulation process%化学-混凝沉淀处理含氟含重金属废水研究

    Institute of Scientific and Technical Information of China (English)

    周芬; 汪晓军

    2012-01-01

    In order to meet the discharge standard of wastewater from an aluminum electroplating factory,the performances and impact factors by using chemical coagulation process were studied for removing fluoride and heavy metals simultaneously.The orthogonal and single factor experiments were used to determine the optimal operation conditions.The results show that when the molar ratio of CaCl2 and fluoride is 5∶1(the dosage of CaCl2 is 4 782 mg/L),the dosage of PAC is 500 mg/L and PAM is 2 mg/L,the pH value is adjusted to 9.5,the content of F-and Cu2+,Ni2+,Cr6+,Zn2+ in effluent can be reduced to 8,0.05,0.07,0.3 and 0.1 mg/L,respectively.The effluent can reach the first level criteria of the second period specified in water pollution discharge limits(DB44/26-2001).%为解决某铝材电镀工业园含氟含重金属废水达标排放的问题,研究了化学混凝沉淀法同时处理该废水中氟与金属的效果及影响因素,采用正交和单因素实验确定了最佳工艺条件。结果表明,当CaCl2投加量与废水中氟离子摩尔比为5∶1(即CaCl2质量4 782 mg/L),聚氯化铝(PAC)用量为500 mg/L,pH为9.5,聚丙烯酰胺(PAM)用量2 mg/L时,出水中残留F离子浓度可降至8 mg/L,Cu2+、Ni2+、Cr6+和Zn2+出水浓度分别降至0.05、0.07、0.3和0.1 mg/L,出水能达到《水污染物排放限值》(DB44/26-2001)第二时段一级标准,且最为经济。

  7. Gender and age differences in mixed metal exposure and urinary excretion

    Energy Technology Data Exchange (ETDEWEB)

    Berglund, Marika, E-mail: Marika.Berglund@ki.se [Institute of Environmental Medicine, Karolinska Institutet, Stockholm (Sweden); Lindberg, Anna-Lena [Institute of Environmental Medicine, Karolinska Institutet, Stockholm (Sweden); Rahman, Mahfuzar; Yunus, Mohammad [International Centre for Diarrhoeal Disease Research (Bangladesh); Grander, Margaretha [Institute of Environmental Medicine, Karolinska Institutet, Stockholm (Sweden); Loennerdal, Bo [Department of Nutrition, University of California, Davis, CA 95616 (United States); Vahter, Marie [Institute of Environmental Medicine, Karolinska Institutet, Stockholm (Sweden)

    2011-11-15

    Background: Little is known about the variation in exposure to toxic metals by age and gender and other potential modifying factors. We evaluated age and gender differences by measurements of metal/element concentrations in urine in a rural population in Matlab, Bangladesh, in three age groups: 8-12 (N=238), 14-15 (N=107) and 30-88 (N=710) years of age, living in an area with no point sources of metal exposure but where elevated water arsenic concentrations are prevalent. Results: We found marked differences in urine concentrations of metals and trace elements by gender, age, tobacco use, socioeconomic and nutritional status. Besides a clearly elevated urinary arsenic concentration in all age groups (medians 63-85 {mu}g As/L), and despite the low degree of contamination from industries and traffic, the urine concentrations of toxic metals such as cadmium and lead were clearly elevated, especially in children (median 0.31 {mu}g Cd/L and 2.9 {mu}g Pb/L, respectively). In general, women had higher urinary concentrations of toxic metals, especially Cd (median 0.81 {mu}g/L) compared to men (0.66 {mu}g/L) and U (median 10 ng/L in women, compared to 6.4 ng/L in men), while men had higher urinary concentrations of the basic and essential elements Ca (69 mg/L in men, 30-50 years, compared to 52 mg/L in women), Mg (58 mg/L in men compared to 50 mg/L in women), Zn (182 {mu}g/L in men compared to 117 {mu}g/L in women) and Se (9.9 {mu}g/L in men compared to 8.7 {mu}g/L in women). Manganese was consistently higher in females than in males in all age groups, suggesting a biological difference between females and males in Mn metabolism. Increasing socioeconomic status decreased the toxic metal exposure significantly in children and especially in men. Poor iron status was detected in 17% of children, adolescents and women, but only in 6% of men. Also zinc deficiency was more prevalent in females than in males. Conclusions: Women and children seemed to be more at risk for toxic

  8. Small molecule fluoride toxicity agonists.

    Science.gov (United States)

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

    2015-04-23

    Fluoride is a ubiquitous anion that inhibits a wide variety of metabolic processes. Here, we report the identification of a series of compounds that enhance fluoride toxicity in Escherichia coli and Streptococcus mutans. These molecules were isolated by using a high-throughput screen (HTS) for compounds that increase intracellular fluoride levels as determined via a fluoride riboswitch reporter fusion construct. A series of derivatives were synthesized to examine structure-activity relationships, leading to the identification of compounds with improved activity. Thus, we demonstrate that small molecule fluoride toxicity agonists can be identified by HTS from existing chemical libraries by exploiting a natural fluoride riboswitch. In addition, our findings suggest that some molecules might be further optimized to function as binary antibacterial agents when combined with fluoride. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Fluoride Rinses, Gels and Foams

    DEFF Research Database (Denmark)

    Twetman, Svante; Keller, Mette K

    2016-01-01

    AIM: The aim of this conference paper was to systematically review the quality of evidence and summarize the findings of clinical trials published after 2002 using fluoride mouth rinses, fluoride gels or foams for the prevention of dental caries. METHODS: Relevant papers were selected after...... an electronic search for literature published in English between 2003 and 2014. The included papers were assessed for their risk of bias and the results were narratively synthesized due to study heterogeneity. The quality of evidence was expressed according to GRADE. RESULTS: A total of 19 papers were included...... (6 on fluoride mouth rinse, 10 on fluoride gel and 3 on fluoride foam); 6 had a low risk of bias while 2 had a moderate risk. All fluoride measures appeared to be beneficial in preventing crown caries and reversing root caries, but the quality of evidence was graded as low for fluoride mouth rinse...

  10. Small Molecule Fluoride Toxicity Agonists

    Science.gov (United States)

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

    2015-01-01

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

  11. Mixed-Valent NaCu 4 Se 3: A Two-Dimensional Metal

    Energy Technology Data Exchange (ETDEWEB)

    Sturza, Mihai; Bugaris, Daniel E.; Malliakas, Christos D.; Han, Fei; Chung, Duck Young; Kanatzidis, Mercouri G.

    2016-05-04

    The new ternary copper selenide NaCu4Se3 crystallizes in the RbCd4As3 structure type with the trigonal space group R3m and lattice constants a = 4.0316(4) angstrom and c = 31.438(8) angstrom. Its structure is built from two-dimensional slabs of 2 [Cu4Se3] separated by Na+ cations. The compound is formally mixed-valent with Se2-/Se- atoms and exhibits metallic properties. It is a hole conductor with an electrical conductivity of similar to 300 S cm-1 at room temperature and a thermopower of similar to 10 mu V K-1. Hall effect measurements indicate holes as the dominant carrier with a concentration of similar to 6.12(1) X 1021 cm-3 at 300 K. Density functional theory electronic structure calculations indicate p -type metallic behavior for the 2 [Cu4Se3] framework, which is in a good agreement with the experimental metallic conductivity and Pauli paramagnetism.

  12. Fermi surfaces, spin-mixing parameter, and colossal anisotropy of spin relaxation in transition metals from ab initio theory

    Science.gov (United States)

    Zimmermann, Bernd; Mavropoulos, Phivos; Long, Nguyen H.; Gerhorst, Christian-Roman; Blügel, Stefan; Mokrousov, Yuriy

    2016-04-01

    The Fermi surfaces and Elliott-Yafet spin-mixing parameter (EYP) of several elemental metals are studied by ab initio calculations. We focus first on the anisotropy of the EYP as a function of the direction of the spin-quantization axis [B. Zimmermann et al., Phys. Rev. Lett. 109, 236603 (2012), 10.1103/PhysRevLett.109.236603]. We analyze in detail the origin of the gigantic anisotropy in 5 d hcp metals as compared to 5 d cubic metals by band structure calculations and discuss the stability of our results against an applied magnetic field. We further present calculations of light (4 d and 3 d ) hcp crystals, where we find a huge increase of the EYP anisotropy, reaching colossal values as large as 6000 % in hcp Ti. We attribute these findings to the reduced strength of spin-orbit coupling, which promotes the anisotropic spin-flip hot loops at the Fermi surface. In order to conduct these investigations, we developed an adapted tetrahedron-based method for the precise calculation of Fermi surfaces of complicated shape and accurate Fermi-surface integrals within the full-potential relativistic Korringa-Kohn-Rostoker Green function method.

  13. Synthesis, Spectroscopic Characterisation, and Biopotential and DNA Cleavage Applications of Mixed Ligand 4-N,N-Dimethylaminopyridine Metal Complexes

    Directory of Open Access Journals (Sweden)

    C. Surendra Dilip

    2013-01-01

    Full Text Available The mixed ligand transition metal complexes of 4-N,N-dimethylaminopyridine (DP and chloride as primary and secondary ligands with the general formula [M(DP3Cl3]; M = Cr(III and Fe(III; [M′(DP4Cl2]M′ = Co(II, Ni(II, Cu(II, and Cd(II were synthesized in a microwave oven. The complexes were characterized by FT-IR and UV, 1HNMR, 13CNMR spectra, TG/DTG, and various physicoanalytical techniques. From the magnetic moment measurements and the electronic spectral data, a distorted octahedral geometry was proposed for the complexes. The complexes express similar trend of thermal behaviour such that they lose water of hydration initially with the subsequent emission of organic and inorganic fragments and leave left the metal oxides as residue. The activation thermodynamic parameters, such as , , , and of the metal complexes, illustrate the spontaneous formation of the complexes. The antimicrobial studies against various pathogenic bacterial and fungal serums insist on that the enhanced potential of the complexes over their ligand and their biopotential properties increases with concentration. The DNA interaction of the synthesized complexes on CT-DNA was investigated by UV-Vis spectroscopy, viscosity, thermal denaturation, and electroanalytical experiments and their binding constants ( were also calculated.

  14. Fluoride and Oral Health

    DEFF Research Database (Denmark)

    O'Mullane, D M; Baez, R J; Jones, S

    2016-01-01

    and strategies is noteworthy. This updated version of ‘Fluoride and Oral Health’ has adopted an evidence-based approach to its commentary on the different fl uoride vehicles and strategies and also to its recommendations. In this regard, full account is taken of the many recent systematic reviews published...

  15. How Does Fluoride Work?

    Science.gov (United States)

    ... A Movies & More Quizzes Kids' Dictionary of Medical Words En Español What Other Kids Are Reading 7 Videos: Kids Talk About ... There's fluoride in your toothpaste and even in your water. But how does it work to keep teeth ...

  16. Histopathological changes of renal tissue following sodium fluoride administration in two consecutive generations of mice. Correlation with the urinary elimination of fluoride.

    Science.gov (United States)

    Dimcevici Poesina, Nicoleta; Bălălău, Cristian; Nimigean, Vanda Roxana; Nimigean, Victor; Ion, Ion; Baconi, Daniela; Bârcă, Maria; Băran Poesina, Violeta

    2014-01-01

    The present study was designed to investigate the toxic effects (evaluated as histopathological changes) of sodium fluoride on the kidney in two consecutive generations of NMRI mice. An attempt to correlate the toxicity with the urinary elimination of fluoride has been made, as urinary fluoride excretion has been widely used as an indicator of fluoride intake and exposure. Six mixed (males and females) animal groups have been constituted by dividing the populations of mice derived from pregnant females (named "mothers" 0.5 mg sodium fluoride) treated with 0.5 mg sodium fluoride by daily gavage and pregnant females (named "mothers" 0.25 mg sodium fluoride) treated with 0.25 mg sodium fluoride by daily gavage; three types of sodium fluoride treatments were administrated: homeopathic, allopathic-homeopathic and allopathic. When the animals reached the adulthood, by randomization, they were selected in pairs for giving birth to the second generation of mice. No treatments were administrated to the second generation of mice; thus, the urinary elimination of fluoride in the second generation is attributed to exposure at sodium fluoride before birth. The administration of sodium fluoride to the first generation (F1) is realized until the mice reached the adulthood. For the first generation, the urine was collected at three times, every three weeks: at the age of four weeks, seven weeks and 11 weeks; single sampling urine, at the age of four weeks, has been conducted for the second generation. The urine samples have been analyzed using the ion selective electrode method for fluoride. For the histopathological examination, the animals were killed by cervical dislocation; the kidneys were collected in a 10% formalin solution. The preparation of samples for optical microscopy was realized with Hematoxylin-Eosin staining. The results indicate that the elimination of fluoride was similar (at the second evaluation, at 7-week-old of the first generation) for the both generations

  17. Salt fluoridation and oral health

    Directory of Open Access Journals (Sweden)

    Thomas M. Marthaler

    2013-11-01

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

  18. Storage capacity and oxygen mobility in mixed oxides from transition metals promoted by cerium

    Science.gov (United States)

    Perdomo, Camilo; Pérez, Alejandro; Molina, Rafael; Moreno, Sonia

    2016-10-01

    The oxygen mobility and storage capacity of Ce-Co/Cu-MgAl or Ce-MgAl mixed oxides, obtained by hydrotalcite precursors, were evaluated using Toluene-temperature-programmed-reaction, 18O2 isotopic exchange and O2-H2 titration. The presence of oxygen vacancies-related species was evaluated by means of Electron Paramagnetic Resonance. A correlation was found between the studied properties and the catalytic activity of the oxides in total oxidation processes. It was evidenced that catalytic activity depends on two related processes: the facility with which the solid can be reduced and its ability to regenerate itself in the presence of molecular oxygen in the gas phase. These processes are enhanced by Cu-Co cooperative effect in the mixed oxides. Additionally, the incorporation of Ce in the Co-Cu catalysts improved their oxygen transport properties.

  19. Control of differential strain during heating and cooling of mixed conducting metal oxide membranes

    Science.gov (United States)

    Carolan, Michael Francis

    2007-12-25

    Method of operating an oxygen-permeable mixed conducting membrane having an oxidant feed side and a permeate side, which method comprises controlling the differential strain between the oxidant feed side and the permeate side by varying either or both of the oxygen partial pressure and the total gas pressure on either or both of the oxidant feed side and the permeate side of the membrane while changing the temperature of the membrane from a first temperature to a second temperature.

  20. Storage capacity and oxygen mobility in mixed oxides from transition metals promoted by cerium

    Energy Technology Data Exchange (ETDEWEB)

    Perdomo, Camilo [Estado Sólido y Catálisis Ambiental (ESCA), Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Carrera 30 45-03, Bogotá (Colombia); Pérez, Alejandro [Grupo de Investigación Fitoquímica (GIFUJ), Departamento de Química, Facultad de Ciencias, Pontificia Universidad Javeriana, Carrera 7 No. 43-82, Bogotá D.C (Colombia); Molina, Rafael [Estado Sólido y Catálisis Ambiental (ESCA), Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Carrera 30 45-03, Bogotá (Colombia); Moreno, Sonia, E-mail: smorenog@unal.edu.co [Estado Sólido y Catálisis Ambiental (ESCA), Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Carrera 30 45-03, Bogotá (Colombia)

    2016-10-15

    Highlights: • Ce addition to the catalysts improves the availability of oxygen in the materials. • Mixed oxide with Co and Cu exhibits the best oxygen transport properties. • Co presence improves O{sub 2} mobility in the catalysts. • The presence of Cu in the solids improves redox properties. - Abstract: The oxygen mobility and storage capacity of Ce-Co/Cu-MgAl or Ce–MgAl mixed oxides, obtained by hydrotalcite precursors, were evaluated using Toluene-temperature-programmed-reaction, {sup 18}O{sub 2} isotopic exchange and O{sub 2}-H{sub 2} titration. The presence of oxygen vacancies-related species was evaluated by means of Electron Paramagnetic Resonance. A correlation was found between the studied properties and the catalytic activity of the oxides in total oxidation processes. It was evidenced that catalytic activity depends on two related processes: the facility with which the solid can be reduced and its ability to regenerate itself in the presence of molecular oxygen in the gas phase. These processes are enhanced by Cu-Co cooperative effect in the mixed oxides. Additionally, the incorporation of Ce in the Co-Cu catalysts improved their oxygen transport properties.

  1. Bioleaching of metal from municipal waste incineration fly ash using a mixed culture of sulfur-oxidizing and iron-oxidizing bacteria.

    Science.gov (United States)

    Ishigaki, Tomonori; Nakanishi, Akane; Tateda, Masafumi; Ike, Michihiko; Fujita, Masanori

    2005-08-01

    We investigated the behavior and characteristics of metal leaching from municipal solid waste incineration (MSWI) fly ash among pure cultures of a sulfur-oxidizing bacterium (SOB) and an iron-oxidizing bacterium (IOB) and a mixed culture. The IOB has a high metal-leaching ability, though its tolerability against the ash addition is low. The SOB might better tolerate an increase in ash addition than the IOB, though metal leaching ability of the SOB is limited. Mixed culture could compensate for these deficiencies, and high metal leachability was exhibited in the 1% ash culture, i.e., 67% and 78% of leachabilities for Cu and Zn, respectively, and 100% for Cr and Cd. Furthermore, comparably high leachabilities such as 42% and 78% for Cu and Zn were observed even in the 3% ash cultures. Characterization of metal leaching by the mixed culture revealed that the acidic and oxidizing condition had remained stable thorough the experimental period. Ferric iron remained in the mixed culture, and the metal leaching was enhanced by redox mechanisms coupling with the leaching by sulfate. An increase of ferrous iron enhanced the Cr, Cu, and As leaching. The optimum concentration of sulfur existed for As and Cr (5 gl(-1)) and Cu (2 gl(-1)). The presence of the degradable and non-degradable organic compound that must be existed in the natural environment or waste landfills made no significant change in the leachability of metals other than Zn. These results suggested that bioleaching using a mixed culture of SOB and IOB is a promising technology for recovering the valuable metals from MSWI fly ash.

  2. Thermodynamic properties and mixing thermodynamic parameters of Ba-Al, Mg-Al, Sr-Al and Cu-Al metallic melts

    Institute of Scientific and Technical Information of China (English)

    张鉴

    2004-01-01

    Application of equations of mixing thermodynamic parameters formulated on the basis of the coexistence theory of metallic melts in Ba-Al, Mg-Al, Sr-A1 and Cu-Al melts leads to fruitful results that not only the evaluated mass action concentrations agree well with the measured activities, but also the calculated mixing thermodynamic parameters are quite coincident with the experimental values. Moreover, the calculated mass action concentrations strictly obey the mass action law. The evaluated mixing thermodynamic parameters have very fine regularity: the mixing free energy is composed of standard free formation energies of all compounds and chemical potentials of all structural units at equilibrium; the mixing enthalpy consists of standard formation enthalpies of all compounds; the mixing entropy is composed of standard entropies of all compounds and configuration entropies of all structural units at equilibrium. As the equations of mixing thermodynamic parameters formulated are widely applicable to metallic melts involving compound formation, they can be used as the second practical criterion to determine whether thermodynamic models of metallic melts are correctly formulated.

  3. Ferroelastic phase transition in cryolite, Na3AlF6, a mixed fluoride perovskite: High temperature single crystal X-ray diffraction study and symmetry analysis of the transition mechanism

    Science.gov (United States)

    Yang, Hexiong; Ghose, Subrata; Hatch, Dorian M.

    1993-04-01

    Cryolite, Na3AlF6[ = 2Na+(Na0.5 +Al0.5 3+)F3] is a mixed fluoride perovskite, in which the corner-sharing octahedral framework is formed by alternating [NaF6] and [AlF6] octahedra and the cavities are occupied by Na+ ions. At 295 K, it is monoclinic ( α phase), space group P2 1/ n with a = 5.4139 (7), b = 5.6012 (5) and c = 7.7769 (8) Å and β = 90.183 (3)∘, Z = 2. A high temperature single crystal X-ray diffraction study in the range 295 900 K indicates a fluctuation-induced first-order phase transition from monoclinic to orthorhombic symmetry at T 0 ˜ 885 K, in contrast to a previous report that it becomes cubic at ˜823 K. The space group of the high temperature β phase is Immm with a = 5.632 (4), b = 5.627 (3) and c = 7.958 (4) Å, Z = 2 at 890 K. Above T 0, the coordination number of the Na+ ion in the cavity increases from eight to twelve and the zigzag Na1 — Al octahedral chains parallel to c become straight with the Na1-F-Al angle = 180 °. The phase transition is driven by two coupled primary order parameters. The first corresponds to the rotation of the nearly rigid [AlF6] group and transforms according to the Γ 4 + irreducible representation of Immm. Coupled to the [AlF6] rotation is a second primary order parameter corresponding to the displacement of the Na2+ ion in the cavity from its equilibrium position. This order parameter transforms according to the X 3 + irreducible representation of Immm. Following Immm → P2 1 / n phase transition, four equivalent domains of P2 1/ n are determined relative to Immm, which are in an antiphase and/or twin relationship. The abrupt shortening of the octahedral Al-F and Na-F bonds and a sudden change in orientations of the atomic thermal vibration ellipsoids above T 0 indicate a crossover from displacive to an order-disorder mechanism near the transition temperature. The β phase is interpreted as a dynamic average of four micro-twin and -antiphase domains of the a phase. This view is consistent with the

  4. Metal releases from a municipal solid waste incineration air pollution control residue mixed with compost.

    Science.gov (United States)

    Van Praagh, M; Persson, K M

    2008-08-01

    The influence of 10 wt.% mature compost was tested on the heavy metal leachate emissions from a calcium-rich municipal solid waste incineration air pollution control residue (MSWI APC). Apart from elongated columns (500 and 1250 mm), an otherwise norm compliant European percolation test setup was used. More than 99% of the metals Al, As, Cd, Cr, Cu, Fe and Ni were left in the APC residue after leaching to a liquid-to-solid ratio (L/S) of 10. Apparent short-term effects of elevated leachate DOC concentrations on heavy metal releases were not detected. Zn and Pb leachate concentrations were one order of magnitude lower for L/S 5 and 10 from the pure APC residue column, which suggests a possible long-term effect of compost on the release of these elements. Prolonging the contact time between the pore water and the material resulted in elevated leachate concentrations at L/S 0.1 to L/S 1 by a factor of 2. Only Cr and Pb concentrations were at their maxima in the first leachates at L/S 0.1. Equilibrium speciation modelling with the PHREEQC code suggested portlandite (Ca(OH)2) to control Ca solubility and pH.

  5. Mixed valence transition metal 2D-oxides: Comparison between delafossite and crednerite compounds

    Science.gov (United States)

    Martin, Christine; Poienar, Maria

    2017-08-01

    Transition metal oxides offer large opportunities to study relationships between structures and properties. Indeed these compounds crystallize in numerous frameworks corresponding to different dimensionalities and, accordingly, show a huge variety of properties (as high Tc superconductivity, colossal magnetoresistivity, multiferroicity..). The control of the oxidation state of the transition metal, via the monitoring of the oxygen content, is of prime importance to understand and optimize the properties, due to the strong coupling that exists between the lattice and the charges and spins of the transition metals. In this large playground for chemists, we reinvestigated several 2D-compounds derived from delafossite structure. Considering this paper as a very short review, we report here the results obtained on CuMO2 compounds (with M = Cr, Mn or Mn+Cu) by using a combination of techniques, as X-ray, neutrons and/or electrons diffraction on poly-crystals for structural characterisations that are correlated with electrical and/or magnetic properties. The complementarity of studies is also addressed by the synthesis and characterization of single crystals in addition to poly-crystals. Moreover the comparison of the structures of similar Cr and Mn based oxides highlights the crucial role of the Jahn-Teller effect of trivalent manganese to lift the degeneracy, which is responsible of the magnetic frustration in CuCrO2.

  6. METHOD OF PRODUCING URANIUM METAL BY ELECTROLYSIS

    Science.gov (United States)

    Piper, R.D.

    1962-09-01

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

  7. Health Effects Associated with Water Fluoridation.

    Science.gov (United States)

    Richmond, Virginia L.

    1979-01-01

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

  8. Industrial fluoride pollution: chronic fluoride poisoning in Cornwall Island cattle

    Energy Technology Data Exchange (ETDEWEB)

    Krook, L.; Maylin, G.A.

    1979-04-01

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

  9. Corrosion investigations on zircaloy-4 and titanium dissolver materials for MOX fuel dissolution in concentrated nitric acid containing fluoride ions

    Science.gov (United States)

    Jayaraj, J.; Krishnaveni, P.; Krishna, D. Nanda Gopala; Mallika, C.; Mudali, U. Kamachi

    2016-05-01

    Aqueous reprocessing of plutonium-rich mixed oxide fuels require fluoride as a dissolution catalyst in boiling nitric acid for an effective dissolution of the spent fuel. High corrosion rates were obtained for the candidate dissolver materials zircaloy-4 (Zr-4) and commercial pure titanium (CP-Ti grade 2) in boiling 11.5 M HNO3 + 0.05 M NaF. Complexing the fluoride ions either with Al(NO3)3 or ZrO(NO3)2 aided in decreasing the corrosion rates of Zr-4 and CP-Ti. From the obtained corrosion rates it is concluded that CP-Ti is a better dissolver material than Zr-4 for extended service life in boiling 11.5 M HNO3 + 0.05 M NaF, when complexed with 0.15 M ZrO(NO3)2. XPS analysis confirmed the presence of TiO2 and absence of fluoride on the surface of CP-Ti samples, indicating that effective complexation had occurred in solution leading to passivation of the metal and imparting high corrosion resistance.

  10. Exchange bias in a mixed metal oxide based magnetocaloric compound YFe0.5Cr0.5O3

    Science.gov (United States)

    Sharma, Mohit K.; Singh, Karan; Mukherjee, K.

    2016-09-01

    We report a detailed investigation of magnetization, magnetocaloric effect and exchange bias studies on a mixed metal oxide YFe0.5Cr0.5O3 belonging to perovskite family. Our results reveal that the compound is in canted magnetic state (CMS) where ferromagnetic correlations are present in an antiferromagnetic state. Magnetic entropy change of this compound follows a power law (∆SM∼Hm) dependence of magnetic field. In this compound, inverse magnetocaloric effect (IMCE) is observed below 260 K while conventional magnetocaloric effect (CMCE) above it. The exponent 'm' is found to be independent of temperature and field only in the IMCE region. Investigation of temperature and magnetic field dependence studies of exchange bias, reveal a competition between effective Zeeman energy of the ferromagnetic regions and anisotropic exchange energy at the interface between ferromagnetic and antiferromagnetic regions. Variation of exchange bias due to temperature and field cycling is also investigated.

  11. Novel metal complexes of mixed piperaquine-acetaminophen and piperaquine-acetylsalicylic acid: Synthesis, characterization and antimicrobial activities

    Directory of Open Access Journals (Sweden)

    Yusuf Oloruntoyin Ayipo

    2016-11-01

    Full Text Available Synthesis of coordination compounds of Zinc(II, Copper(II, Nickel(II, Cobalt(II and Iron(II with mixed piperaquine-acetaminophen and piperaquine-acetylsalicylic acid has been studied. The complexes were characterized via: solubility test, melting point determination, conductivity measurement, Atomic Absorption Spectroscopy, UV-Visible Spectroscopy, FTIR Spectroscopy and magnetic susceptibility. The complexes were proposed to have a stoichiometry ratio of 1:1:1 between each metal salt and the ligands with tetrahedral and octahedral geometry following the reaction pattern of MX.yH2O + L1L2/3 to give ML1L2/3X.yH2O. Biological activities of the synthesized complexes have been evaluated against Escherichia coli and Staphylococcus aureus.

  12. High index fluoride materials for 193nm immersion lithography

    Science.gov (United States)

    Nawata, T.; Inui, Y.; Masada, I.; Nishijima, E.; Satoh, H.; Fukuda, T.

    2006-03-01

    We tried to investigate various kinds of metal fluoride materials which have higher gravity than CaF II and cubic crystal system, and we found out barium lithium fluoride (BaLiF 3) and potassium yttrium fluoride (KY 3F 10) as candidates for the last lens material. We have developed unique Czochralski (CZ) machines and techniques for the growth of large calcium fluoride single crystals. And we applied these technologies to the growth of fluoride high index materials. We have succeeded to grow the large BaLiF 3 single crystal with 120mm in diameter and a KY 3F 10 single crystal, and measured their basic properties such as refractive index, VUV transmittance, birefringence, and so on. As a result of our basic research, we found out that BaLiF 3 single crystal is transparent at VUV region, and the refractive index at 193nm is 1.64, and KY 3F 10 single crystal has the index of 1.59 at the wavelength of 193nm which is slightly higher than fused silica. We expect that these fluoride high index materials are useful for the last lens material of the next generation immersion lithography.

  13. Effect of rotational mixing and metallicity on the hot star wind mass-loss rates

    CERN Document Server

    Krticka, Jiri

    2014-01-01

    Hot star wind mass-loss rates depend on the abundance of individual elements. This dependence is usually accounted for assuming scaled solar chemical composition. However, this approach may not be justified in evolved rotating stars. The rotational mixing brings CNO-processed material to the stellar surface, increasing the abundance of nitrogen at the expense of carbon and oxygen, which potentially influences the mass-loss rates. We study the influence of the modified chemical composition resulting from the rotational mixing on the wind parameters, particularly the wind mass-loss rates. We use our NLTE wind code to predict the wind structure and compare the calculated wind mass-loss rate for the case of scaled solar chemical composition and the composition affected by the CNO cycle. We show that for a higher mass-fraction of heavier elements $Z/Z_\\odot\\gtrsim0.1$ the change of chemical composition from the scaled solar to the CNO-processed scaled solar composition does not significantly affect the wind mass-l...

  14. Synthesis, spectral and thermal studies of some transition metal mixed ligand complexes: modeling of equilibrium composition and biological activity.

    Science.gov (United States)

    Neelakantan, M A; Sundaram, M; Nair, M Sivasankaran

    2011-09-01

    Several mixed ligand Ni(II), Cu(II) and Zn(II) complexes of 2-amino-3-hydroxypyridine (AHP) and imidazoles viz., imidazole (him), benzimidazole (bim), histamine (hist) and L-histidine (his) have been synthesized and characterized by elemental and spectral (vibrational, electronic, 1H NMR and EPR) data as well as by magnetic moment values. On the basis of elemental analysis and molar conductance values, all the complexes can be formulated as [MAB]Cl except histidine complexes as MAB. Thermogravimetric studies reveal the presence of coordinated water molecules in most of the complexes. From the magnetic measurements and electronic spectral data, octahedral structure was proposed for Ni(II) and Cu(II)-AHP-his, tetrahedral for Cu(II)-AHP-him/bim/hist, but square planar for the Cu(II)-AHP complex. The g∥/A∥ calculated supports tetrahedral environment around the Cu(II) in Cu(II)-AHP-him/bim/hist and distorted octahedral for Cu(II)-AHP-his complexes. The morphology of the reported metal complexes was investigated by scanning electron micrographs (SEM). The potentiometric study has been performed in aqueous solution at 37 °C and I=0.15 mol dm(-3) NaClO4. MABH, MAB and MAB2 species has been identified in the present systems. Proton dissociation constants of AHP and stability constants of metal complexes were determined using MINIQUAD-75. The most probable structure of the mixed ligand species is discussed based upon their stability constants. The in vitro biological activity of the complexes was tested against the Gram positive and Gram negative bacteria, fungus and yeast. The oxidative DNA cleavage studies of the complexes were performed using gel electrophoresis method. Cu(II) complexes have been found to promote DNA cleavage in presence of biological reductant such as ascorbate and oxidant like hydrogen peroxide.

  15. Synthesis, spectral and thermal studies of some transition metal mixed ligand complexes: Modeling of equilibrium composition and biological activity

    Science.gov (United States)

    Neelakantan, M. A.; Sundaram, M.; Nair, M. Sivasankaran

    2011-09-01

    Several mixed ligand Ni(II), Cu(II) and Zn(II) complexes of 2-amino-3-hydroxypyridine (AHP) and imidazoles viz., imidazole (him), benzimidazole (bim), histamine (hist) and L-histidine (his) have been synthesized and characterized by elemental and spectral (vibrational, electronic, 1H NMR and EPR) data as well as by magnetic moment values. On the basis of elemental analysis and molar conductance values, all the complexes can be formulated as [MAB]Cl except histidine complexes as MAB. Thermogravimetric studies reveal the presence of coordinated water molecules in most of the complexes. From the magnetic measurements and electronic spectral data, octahedral structure was proposed for Ni(II) and Cu(II)-AHP-his, tetrahedral for Cu(II)-AHP-him/bim/hist, but square planar for the Cu(II)-AHP complex. The g∥/ A∥ calculated supports tetrahedral environment around the Cu(II) in Cu(II)-AHP-him/bim/hist and distorted octahedral for Cu(II)-AHP-his complexes. The morphology of the reported metal complexes was investigated by scanning electron micrographs (SEM). The potentiometric study has been performed in aqueous solution at 37 °C and I = 0.15 mol dm -3 NaClO 4. MABH, MAB and MAB 2 species has been identified in the present systems. Proton dissociation constants of AHP and stability constants of metal complexes were determined using MINIQUAD-75. The most probable structure of the mixed ligand species is discussed based upon their stability constants. The in vitro biological activity of the complexes was tested against the Gram positive and Gram negative bacteria, fungus and yeast. The oxidative DNA cleavage studies of the complexes were performed using gel electrophoresis method. Cu(II) complexes have been found to promote DNA cleavage in presence of biological reductant such as ascorbate and oxidant like hydrogen peroxide.

  16. Synthesis of Mg{sub 2}FeH{sub 6} containing as additives transition metal and transition metal fluorides or carbon; Sintese de Mg{sub 2}FeH{sub 6} contando como aditivos metais de transicao e fluoretos de metais de transicao ou carbono

    Energy Technology Data Exchange (ETDEWEB)

    Zepon, G.; Leiva, D.R.; Botta, W.J., E-mail: guizepon@yahoo.com.b [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais

    2010-07-01

    The Mg{sub 2}FeH{sub 6} is a promising way of storing hydrogen in solid form, composed by elements that have low cost and, at the same time, high volumetric storage density: 150 kg H{sub 2}/m{sup 3}. However, this complex hydride is not easily synthesized as a single phase material. The hydrogen sorption high temperature and slow kinetics are the major limitations for the practical application of the Mg{sub 2}FeH{sub 6} as a hydrogen storage material. Little is known about the effects of additives in Mg{sub 2}FeH{sub 6} based nanocomposites in this work were synthesized by MAE under hydrogen atmosphere nanocomposites based on Mg{sub 2}FeH{sub 6} containing additives as transition metals, transition metals fluorides of transition metals or carbon, in order to obtain information on the effects of the selected additives. To this end, we used characterization techniques such as XRD, SEM and TEM, thermal analysis by DSC and curves made in apparatus PCT.(author)

  17. A MIXED BOOLEAN AND DEPOSIT MODEL FOR THE MODELING OF METAL PIGMENTS IN PAINT LAYERS

    Directory of Open Access Journals (Sweden)

    Enguerrand Couka

    2015-06-01

    Full Text Available Pigments made of metal particles of around 10 µm or 20 µm produce sparkling effects in paints, due to the specular reflection that occurs at this scale. Overall, the optical aspect of paints depend on the density and distribution in space of the particles. In this work, we model the dispersion of metal particles of size up to 50 µm, visible to the eyes, in a paint layer. Making use of optical and scanning electron microscopy (SEM images, we estimate the dispersion of particles in terms of correlation functions. Particles tend to aggregate into clusters, as shown by the presence of oscillations in the correlation functions. Furthermore, the volume fraction of particles is non-uniform in space. It is highest in the middle of the layer and lowest near the surfaces of the layer. To model this microstructure, we explore two models. The first one is a deposit model where particles fall onto a surface. It is unable to reproduce the observed measurements. We then introduce a "stack" model where clusters are first modeled by a 2D Poisson point process, and a bi-directional deposit model is used to implant particles in each cluster. Good agreement is found with respect to SEM images in terms of correlation functions and density of particles along the layer height.

  18. Ligand Symmetry Modulation for Designing Mixed-Ligand Metal-Organic Frameworks: Gas Sorption and Luminescence Sensing Properties.

    Science.gov (United States)

    Chen, Di-Ming; Tian, Jia-Yue; Liu, Chun-Sen

    2016-09-06

    Herein, we report the synthesis of a new mixed-linker Zn(II)-based metal-organic framework (MOF), {[Zn2(atz)2(bpydb)](DMA)8}n (1) (atz = deprotonated 3-amino-1,2,4-triazole, bpydb = deprotonated 4,4'-(4,4'-bipyridine-2,6-diyl) dibenzoic acid, DMA = N,N-dimethylacetamide), through symmetry modulation of a triazole ligand. The desymmetrized triazole linkers not only bond to the Zn(II) ions to result in a new helical Zn-triazolate chain building unit but also lead to the formation of a highly porous framework (N2 uptake: 617 cm(3)/g; BET surface area: 2393 m(2)/g) with 1D helical channels. The adsorption properties of desolved 1 were investigated by H2, C2H2, CO2, and CH4 sorption experiments, which showed that 1 exhibited high uptake capacity for H2 at 77 K and C2H2 around room temperature. More importantly, the high C2H2 uptake capacity but low binding energy makes this MOF a promising candidate for effective C2H2 capture from C2H2/CO2 and C2H2/CH4 mixed gases with low regenerative energy cost. In addition, 1 shows potential application for the luminescence sensing of small aromatic molecules picric acid (PA) and p-xylene (PX).

  19. Mathematical Modelling of the Process of Tungsten Fluorides Reduction by Hydrogen

    OpenAIRE

    Brendakov Roman; Shvab Alexander; Brendakov Vladimir

    2016-01-01

    The process of tungsten fluorides reduction by hydrogen is a component part of Fluoride technology of tungsten conversion. Nowadays the researchers are definitely interested in studying this process. It is connected with common use of metal tungsten products in different sectors of the economy, which is the result of unique qualities of this metal. With the help of physical and mathematical modelling of the process of tungsten hexafluoride reduction by hydrogen, it becomes possible to create ...

  20. Probing the acoustic vibrations of complex-shaped metal nanoparticles with four-wave mixing.

    Science.gov (United States)

    Wu, Jian; Xiang, Dao; Hajisalem, Ghazal; Lin, Fan-Cheng; Huang, Jer-Shing; Kuo, Chun-Hong; Gordon, Reuven

    2016-10-17

    We probe the acoustic vibrations of silver nanoprisms and gold nano-octahedrons in aqueous solution with four-wave mixing. The nonlinear optical response shows two acoustic vibrational modes: an in-plane mode of nanoprisms with vertexial expansion and contraction; an extensional mode of nano-octahedrons with longitudinal expansion and transverse contraction. The particles were also analyzed with electron microscopy and the acoustic resonance frequencies were then calculated by the finite element analysis, showing good agreement with experimental observations. The experimental mode frequencies also fit with theoretical approximations, which show an inverse dependence of the mode frequency on the edge length, for both nanoprisms and nano-octahedrons. This technique is promising for in situ monitoring of colloidal growth.

  1. Ni- and Zn-doped hematite obtained by combustion of mixed metal oxinates

    Energy Technology Data Exchange (ETDEWEB)

    Barrero, C.A. [Instituto de Fisica, Universidad de Antioquia, A.A. 1226 Medellin (Colombia); Arpe, J. [Departamento de Fisica, Comision Nacional de Energia Atomica (CNEA), Centro Atomico Constituyentes, Av General Paz 1499, 1650, San Martin, Buenos Aires (Argentina); Sileo, E. [INQUIMAE y Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellon II, Piso 3, Ciudad Universitaria, C1428EHA, Buenos Aires (Argentina); Sanchez, L.C. [Instituto de Fisica, Universidad de Antioquia, A.A. 1226 Medellin (Colombia); Zysler, R. [Centro Atomico Bariloche (CNEA), 8400 S.C. de Bariloche, RN (Argentina); Saragovi, C. [Departamento de Fisica, Comision Nacional de Energia Atomica (CNEA), Centro Atomico Constituyentes, Av General Paz 1499, 1650, San Martin, Buenos Aires (Argentina)]. E-mail: saragovi@cnea.gov.ar

    2004-12-31

    We have studied the changes in the structural and magnetic properties of hematite obtained by a new method based on the combustion of mixed Fe(III){sub 0.95}, Ni(II){sub 0.05}- and Fe(III){sub 0.95}, Zn(II){sub 0.05}-oxinates. Thermogravimetric analysis shows that the decomposition of the mixed oxinates proceeds in an overall weight loss formed at least by two stages and the weight loss is related to the formation of probably CO{sub 2}, N{sub 2} and H{sub 2}O, and a solid residue. X-ray diffraction and Mossbauer spectroscopy reveal that the residue of the thermally treated Fe(III){sub 0.95}, Zn(II){sub 0.05}-oxinate is {alpha}-Fe{sub 2}O{sub 3} and ZnFe{sub 2}O{sub 4}, whereas in the case of Fe(III){sub 0.95}, Ni(II){sub 0.05}-oxinate is Ni-doped {alpha}-Fe{sub 2}O{sub 3} and NiFe{sub 2}O{sub 4}. Results suggest low Ni incorporation into the hematite structure. However, it was difficult to establish if Zn-for-Fe substitution in hematite had taken place. The comparison between the two hematites obtained in this work with a non-doped one shows reduction in the cell parameters, increment in the saturation hyperfine fields, and reduction in the Neel temperatures. The presence of the dopant, vacancy sites and lattice distortion are responsible for these effects.

  2. Crystal structure of the mixed-metal thiophosphate Nb1.18V0.82PS10

    Directory of Open Access Journals (Sweden)

    Joobin Sun

    2015-03-01

    Full Text Available The mixed-metal thiophosphate, Nb1.18V0.82PS10 (niobium vanadium phosphorus decasulfide, has been prepared though solid state reactions using an alkali-metal halide flux. The title compound is isostructural with two-dimensional Nb2PS10. [M2S12] (M = Nb or V dimers built up from two bicapped trigonal prisms and tetrahedral [PS4] units share sulfur atoms to construct 1∞[M2PS10] chains along the a axis. These chains are linked through the disulfide bonds between [PS4] units in adjacent chains to form layers parallel to the ab plane. These layers then stack on top of each other to complete the three-dimensional structure with van der Waals gaps. The M sites are occupied by 59% of Nb and 41% of V and the average M—S and M—M distances in the title compound are in between those of V2PS10 and Nb2PS10. The classical charge balance of the title compound can be represented by [(Nb/V4+]2[P5+][S2−]3[S−]7.

  3. EFFECTS OF ALTERNATE ANTIFOAM AGENTS, NOBLE METALS, MIXING SYSTEMS AND MASS TRANSFER ON GAS HOLDUP AND RELEASE FROM NONNEWTONIAN SLURRIES

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero, H; Mark Fowley, M; Charles Crawford, C; Michael Restivo, M; Robert Leishear, R

    2007-12-24

    Gas holdup tests performed in a small-scale mechanically-agitated mixing system at the Savannah River National Laboratory (SRNL) were reported in 2006. The tests were for a simulant of waste from the Hanford Tank 241-AZ-101 and featured additions of DOW Corning Q2-3183A Antifoam agent. Results indicated that this antifoam agent (AFA) increased gas holdup in the waste simulant by about a factor of four and, counter intuitively, that the holdup increased as the simulant shear strength decreased (apparent viscosity decreased). These results raised questions about how the AFA might affect gas holdup in Hanford Waste Treatment and Immobilization Plant (WTP) vessels mixed by air sparging and pulse-jet mixers (PJMs). And whether the WTP air supply system being designed would have the capacity to handle a demand for increased airflow to operate the sparger-PJM mixing systems should the AFA increase retention of the radiochemically generated flammable gases in the waste by making the gas bubbles smaller and less mobile, or decrease the size of sparger bubbles making them mix less effectively for a given airflow rate. A new testing program was developed to assess the potential effects of adding the DOW Corning Q2-3183A AFA to WTP waste streams by first confirming the results of the work reported in 2006 by Stewart et al. and then determining if the AFA in fact causes such increased gas holdup in a prototypic sparger-PJM mixing system, or if the increased holdup is just a feature of the small-scale agitation system. Other elements of the new program include evaluating effects other variables could have on gas holdup in systems with AFA additions such as catalysis from trace noble metals in the waste, determining mass transfer coefficients for the AZ-101 waste simulant, and determining whether other AFA compositions such as Dow Corning 1520-US could also increase gas holdup in Hanford waste. This new testing program was split into two investigations, prototypic sparger

  4. Fluoride Content in Alcoholic Drinks

    OpenAIRE

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

    2015-01-01

    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 ...

  5. Reaction pathways for catalytic gas-phase oxidation of glycerol over mixed metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Suprun, W.; Glaeser, R.; Papp, H. [Leipzig Univ. (Germany). Inst. of Chemical Technology

    2011-07-01

    Glycerol as a main by-product from bio-diesel manufacture is a cheap raw material with large potential for chemical or biochemical transformations to value-added C3-chemicals. One possible way of glycerol utilization involves its catalytic oxidation to acrylic acid as an alternative to petrochemical routes. However, this catalytic conversion exhibits various problems such as harsh reaction conditions, severe catalyst coking and large amounts of undesired by-products. In this study, the reaction pathways for gas-phase conversion of glycerol over transition metal oxides (Mo, V und W) supported on TiO{sub 2} and SiO{sub 2} were investigated by two methods: (i) steady state experiments of glycerol oxidation and possible reactions intermediates, i.e., acrolein, 3-hydroxy propionaldehyde and acetaldehyde, and (ii) temperature-programmed surface reaction (TPSR) studies of glycerol conversion in the presence and in the absence of gas-phase oxygen. It is shown that the supported W-, V and Mo-oxides possess an ability to catalyze the oxidation of glycerol to acrylic acid. These investigations allowed us to gain a deeper insight into the reaction mechanism. Thus, based on the obtained results, three possible reactions pathways for the selective oxidation of glycerol to acrylic acid on the transition metal-containing catalysts are proposed. The major pathways in presence of molecular oxygen are a fast successive destructive oxidation of glycerol to CO{sub x} and the dehydration of glycerol to acrolein which is a rate-limiting step. (orig.)

  6. Fluoride Removal From Drinking Water by Electrocoagulation Using Iron and Aluminum Electrodes

    Directory of Open Access Journals (Sweden)

    Takdastan

    2014-07-01

    Full Text Available Background Existence of fluoride in drinking water above the permissible level causes human skeletal fluorosis. Objectives Electrocoagulation by iron and aluminum electrodes was proposed for removing fluoride from drinking water. Materials and Methods Effects of different operating conditions such as treatment time, initial pH, applied voltage, type and number of electrodes, the spaces between aluminum and iron electrodes, and energy consumption during electrocoagulation were investigated in the batch reactor. Variable concentrations of fluoride solution were prepared by mixing proper amounts of sodium fluoride with deionized water. Results Experimental results showed that aluminum electrode is more effective in fluoride removal than iron, as in 40 minutes and initial pH of 7.5 at 20 V, the fluoride removal process reached to 97.86%. The final recommendable limit of fluoride (1.5 mg/L was obtained in 10 minutes at 20 V with the aluminum electrode. Conclusions In electrocoagulation with iron and aluminum electrodes, increase of voltage, number of electrodes and reaction time as well as decrease of the spaces between electrodes, enhanced the fluoride removal efficiency from drinking water. In addition the effect of pH and initial concentration of fluoride varied with types of electrodes.

  7. Mixed-valent metals bridged by a radical ligand: fact or fiction based on structure-oxidation state correlations.

    Science.gov (United States)

    Sarkar, Biprajit; Patra, Srikanta; Fiedler, Jan; Sunoj, Raghavan B; Janardanan, Deepa; Lahiri, Goutam Kumar; Kaim, Wolfgang

    2008-03-19

    Electron-rich Ru(acac)2 (acac- = 2,4-pentanedionato) binds to the pi electron-deficient bis-chelate ligands L, L = 2,2'-azobispyridine (abpy) or azobis(5-chloropyrimidine) (abcp), with considerable transfer of negative charge. The compounds studied, (abpy)Ru(acac)2 (1), meso-(mu-abpy)[Ru(acac)2]2 (2), rac-(mu-abpy)[Ru(acac)2]2 (3), and (mu-abcp)[Ru(acac)2]2 (4), were calculated by DFT to assess the degree of this metal-to-ligand electron shift. The calculated and experimental structures of 2 and 3 both yield about 1.35 A for the length of the central N-N bond which suggests a monoanion character of the bridging ligand. The NBO analysis confirms this interpretation, and TD-DFT calculations reproduce the observed intense long-wavelength absorptions. While mononuclear 1 is calculated with a lower net ruthenium-to-abpy charge shift as illustrated by the computed 1.30 A for d(N-N), compound 4 with the stronger pi accepting abcp bridge is calculated with a slightly lengthened N-N distance relative to that of 2. The formulation of the dinuclear systems with monoanionic bridging ligands implies an obviously valence-averaged Ru(III)Ru(II) mixed-valent state for the neutral molecules. Mixed valency in conjunction with an anion radical bridging ligand had been discussed before in the discussion of MLCT excited states of symmetrically dinuclear coordination compounds. Whereas 1 still exhibits a conventional electrochemical and spectroelectrochemical behavior with metal centered oxidation and two ligand-based one-electron reduction waves, the two one-electron oxidation and two one-electron reduction processes for each of the dinuclear compounds Ru2.5(L*-)Ru2.5 reveal more unusual features via EPR and UV-vis-NIR spectroelectrochemistry. In spite of intense near-infrared absorptions, the EPR results show that the first reduction leads to Ru(II)(L*-)Ru(II) species, with an increased metal contribution for system 4*-. The second reduction to Ru(II)(L2-)Ru(II) causes the

  8. A mixed-valent cyclodiphosphazane: Transition metal chemistry and cis/trans isomerisation

    Indian Academy of Sciences (India)

    Guddekoppa S Ananthnag; Joel T Mague; Maravanji S Balakrishna

    2015-06-01

    The hydrolysis of cis-{ClP(-NBu)2P(NHBu)} (1) produced a mixed PIII/PV derivative of cyclodiphosphazane, cis-{(BuNH)P(-NBu)2P(O)H} (2). The treatment of 2 with elemental selenium resulted in the formation of the monoselenide, trans-{(BuNH)P(Se)(-NBu)2P(O)H} (3) in good yield. The reactions of two equivalent of 2 with [Pd(-Cl)(3-C3H5)]2 or [Ru(6--cymene)(-Cl)Cl]2 in dichloromethane afforded corresponding mononuclear complexes, [(3-C3H5)PdCl{(BuNH)P(-NBu)2P(O)H}] (4) and [((6--cymene)RuCl2){(BuNH)P(-NBu)2P(O)H}] (5). The treatment of 2 with M(COD)Cl2 (M = Pd and Pt) in dichloromethane at room temperature gave [MCl2{(BuNH)P(-NBu)2P(O)H}2] (6 M = Pd; 7 M = Pt) in good yield. Owing to the cis/trans isomerisation of the cyclodiphosphazane rings, the complexes 6 and 7 exist as a mixture of two isomers. Various NMR spectroscopic techniques were employed for structural elucidation. The molecular structures of 5 and 7 were established by single crystal X-ray crystallographic studies.

  9. Metal-semiconductor pair nanoparticles by a physical route based on bipolar mixing.

    Science.gov (United States)

    Kala, Shubhra; Theissmann, Ralf; Rouenhoff, Marcel; Kruis, Frank Einar

    2016-03-29

    In this report a methodology is described and demonstrated for preparing Au-Ge pair nanoparticles with known compositions by extending and modifying the basic steps normally used to synthesize nanoparticles in carrier gas. For the formation of pair nanoparticles by bipolar mixing, two oppositely charged aerosols of nanoparticles having the desired size are produced with the help of two differential mobility analyzers. Then both are allowed to pass through a tube, which provides sufficient residence time to result in nanoparticle pair formation due to Brownian collisions influenced by Coulomb forces. The effect of residence time on the formation of nanoparticle pairs as well as the influence of diffusion and discharging is described. Subsequently, necessary modifications to the experimental setup are demonstrated systematically. The kinetics of nanoparticles pair formation in a carrier gas is also calculated and compared with measurements made with the help of an online aerosol size analysis technique. This synthesis of nanoparticle pairs can be seen as a possible route towards Janus-type nanoparticles.

  10. Compartmentation of metals in foliage of Populus tremula grown on soils with mixed contamination. II. Zinc binding inside leaf cell organelles

    Energy Technology Data Exchange (ETDEWEB)

    Vollenweider, Pierre, E-mail: pierre.vollenweider@wsl.c [Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zuercherstrasse 111, 8903 Birmensdorf (Switzerland); Bernasconi, Petra [Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zuercherstrasse 111, 8903 Birmensdorf (Switzerland); Environmental Protection Office (AfU), Aabachstrasse 5, 6300 Zug (Switzerland); Gautschi, Hans-Peter [Centre for Microscopy and Image Analysis (CMI), University of Zurich, Gloriastrasse 30, 8006 Zuerich (Switzerland); Menard, Terry; Frey, Beat; Guenthardt-Goerg, Madeleine S. [Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zuercherstrasse 111, 8903 Birmensdorf (Switzerland)

    2011-01-15

    The phytoextraction potential of plants for removing heavy metals from polluted soils is determined by their capacity to store contaminants in aboveground organs and complex them safely. In this study, the metal compartmentation, elemental composition of zinc deposits and zinc complexation within leaves from poplars grown on soil with mixed metal contamination was analysed combining several histochemical and microanalytical approaches. Zinc was the only heavy metal detected and was stored in several organelles in the form of globoid deposits showing {beta}-metachromasy. It was associated to oxygen anions and different cations, noteworthy phosphorous. The deposit structure, elemental composition and element ratios indicated that zinc was chelated by phytic acid ligands. Maturation processes in vacuolar vs. cytoplasmic deposits were suggested by differences in size and amounts of complexed zinc. Hence, zinc complexation by phytate contributed to metal detoxification and accumulation in foliage but could not prevent toxicity reactions therein. - Zinc contaminants translocated to symplast of aged leaves were detoxified by phytic acid ligands.

  11. Low-temperature synthesis of Mn-based mixed metal oxides with novel fluffy structures as efficient catalysts for selective reduction of nitrogen oxides by ammonia.

    Science.gov (United States)

    Meng, Bo; Zhao, Zongbin; Chen, Yongsheng; Wang, Xuzhen; Li, Yong; Qiu, Jieshan

    2014-10-21

    A series of Mn-based mixed metal oxide catalysts (Co-Mn-O, Fe-Mn-O, Ni-Mn-O) with high surface areas were prepared via low temperature crystal splitting and exhibited extremely high catalytic activity for the low-temperature selective catalytic reduction of nitrogen oxides with ammonia.

  12. Integrated Water Gas Shift Membrane Reactors Utilizing Novel, Non Precious Metal Mixed Matrix Membrane

    Energy Technology Data Exchange (ETDEWEB)

    Ferraris, John

    2013-09-30

    Nanoparticles of zeolitic imidazolate frameworks and other related hybrid materials were prepared by modifying published synthesis procedures by introducing bases, changing stoichiometric ratios, or adjusting reaction conditions. These materials were stable at temperatures >300 °C and were compatible with the polymer matrices used to prepare mixed- matrix membranes (MMMs). MMMs tested at 300 °C exhibited a >30 fold increase in permeability, compared to those measured at 35 °C, while maintaining H{sub 2}/CO{sub 2} selectivity. Measurements at high pressure (up to 30 atm) and high temperature (up to 300 °C) resulted in an increase in gas flux across the membrane with retention of selectivity. No variations in permeability were observed at high pressures at either 35 or 300 °C. CO{sub 2}-induced plasticization was not observed for Matrimid®, VTEC, and PBI polymers or their MMMs at 30 atm and 300 °C. Membrane surface modification by cross-linking with ethanol diamine resulted in an increase in H{sub 2}/CO{sub 2} selectivity at 35 °C. Spectrometric analysis showed that the cross-linking was effective to temperatures <150 °C. At higher temperatures, the cross-linked membranes exhibit a H{sub 2}/CO{sub 2} selectivity similar to the uncross-linked polymer. Performance of the polybenzimidazole (PBI) hollow fibers prepared at Santa Fe Science and Technology (SFST, Inc.) showed increased flux o to a flat PBI membrane. A water-gas shift reactor has been built and currently being optimized for testing under DOE conditions.

  13. Corrosion investigations on zircaloy-4 and titanium dissolver materials for MOX fuel dissolution in concentrated nitric acid containing fluoride ions

    Energy Technology Data Exchange (ETDEWEB)

    Jayaraj, J.; Krishnaveni, P.; Krishna, D. Nanda Gopala; Mallika, C.; Mudali, U. Kamachi, E-mail: kamachi@igcar.gov.in

    2016-05-15

    Aqueous reprocessing of plutonium-rich mixed oxide fuels require fluoride as a dissolution catalyst in boiling nitric acid for an effective dissolution of the spent fuel. High corrosion rates were obtained for the candidate dissolver materials zircaloy-4 (Zr-4) and commercial pure titanium (CP-Ti grade 2) in boiling 11.5 M HNO{sub 3} + 0.05 M NaF. Complexing the fluoride ions either with Al(NO{sub 3}){sub 3} or ZrO(NO{sub 3}){sub 2} aided in decreasing the corrosion rates of Zr-4 and CP-Ti. From the obtained corrosion rates it is concluded that CP-Ti is a better dissolver material than Zr-4 for extended service life in boiling 11.5 M HNO{sub 3} + 0.05 M NaF, when complexed with 0.15 M ZrO(NO{sub 3}){sub 2}. XPS analysis confirmed the presence of TiO{sub 2} and absence of fluoride on the surface of CP-Ti samples, indicating that effective complexation had occurred in solution leading to passivation of the metal and imparting high corrosion resistance. - Highlights: • Zr-4 and CP-Ti exhibited high corrosion rate in boiling fluorinated nitric acid. • Corrosion rate decreased in fluorinated nitric acid containing ZrO(NO{sub 3}){sub 2} and Al(NO{sub 3}){sub 3}. • High inhibiting efficiency is exhibited by 0.15 M ZrO(NO{sub 3}){sub 2} when compared to Al(NO{sub 3}){sub 3}. • Corrosion rates of CP-Ti were negligible in complexed fluorinated nitric acid. • XPS analysis on CP-Ti confirmed the presence of TiO{sub 2} and absence of fluoride.

  14. Atomic-Resolution Visualization of Distinctive Chemical Mixing Behavior of Ni, Co and Mn with Li in Layered Lithium Transition-Metal Oxide Cathode Materials

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Pengfei [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zheng, Jianming [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lv, Dongping [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wei, Yi [Peking Univ., Beijing (China); Zheng, Jiaxin [Peking Univ., Beijing (China); Wang, Zhiguo [Univ. of Electronic Science and Technology of China, Chengdu (China); Kuppan, Saravanan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Yu, Jianguo [Idaho National Lab. (INL), Idaho Falls, ID (United States); Luo, Langli [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Edwards, Danny J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Olszta, Matthew J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Amine, Khalil [Argonne National Lab. (ANL), Argonne, IL (United States); Liu, Jun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Xiao, Jie [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Pan, Feng [Peking Univ., Beijing (China); Chen, Guoying [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zhang, Jiguang [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wang, Chong M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-07-06

    Capacity and voltage fading of layer structured cathode based on lithium transition metal oxide is closely related to the lattice position and migration behavior of the transition metal ions. However, it is scarcely clear about the behavior of each of these transition metal ions. We report direct atomic resolution visualization of interatomic layer mixing of transition metal (Ni, Co, Mn) and lithium ions in layer structured oxide cathodes for lithium ion batteries. Using chemical imaging with aberration corrected scanning transmission electron microscope (STEM) and DFT calculations, we discovered that in the layered cathodes, Mn and Co tend to reside almost exclusively at the lattice site of transition metal (TM) layer in the structure or little interlayer mixing with Li. In contrast, Ni shows high degree of interlayer mixing with Li. The fraction of Ni ions reside in the Li layer followed a near linear dependence on total Ni concentration before reaching saturation. The observed distinctively different behavior of Ni with respect to Co and Mn provides new insights on both capacity and voltage fade in this class of cathode materials based on lithium and TM oxides, therefore providing scientific basis for selective tailoring of oxide cathode materials for enhanced performance.

  15. Mixed convection and stratification phenomena in a heavy liquid metal pool

    Energy Technology Data Exchange (ETDEWEB)

    Tarantino, Mariano, E-mail: mariano.tarantino@enea.it [Italian National Agency for New Technologies, Energy and Sustainable Economic Development, C.R. ENEA Brasimone (Italy); Martelli, Daniele; Barone, Gianluca [Dipartimento di Ingegneria Civile e Industriale, University of Pisa, Largo Lucio Lazzarino, 1-56100 Pisa Italy (Italy); Di Piazza, Ivan [Italian National Agency for New Technologies, Energy and Sustainable Economic Development, C.R. ENEA Brasimone (Italy); Forgione, Nicola [Dipartimento di Ingegneria Civile e Industriale, University of Pisa, Largo Lucio Lazzarino, 1-56100 Pisa Italy (Italy)

    2015-05-15

    Highlights: • Results related to experiments reproducing PLOHS + LOF accident in CIRCE pool facility. • Vertical thermal stratification in large HLM pool. • Transition from forced to natural circulation in HLM pool under DHR conditions. • Heat transfer coefficient measurement in HLM pin bundle. • Nusselt numbers calculations and comparison with correlations. - Abstract: This work deals with an analysis of the first experimental series of tests performed to investigate mixed convection and stratification phenomena in CIRCE HLM large pool. In particular, the tests concern the transition from nominal flow to natural circulation regime, typical of decay heat removal (DHR) regime. To this purpose the CIRCE pool facility has been updated to host a suitable test section in order to reproduce the thermal-hydraulic behaviour of a HLM pool-type reactor. The test section basically consists of an electrical bundle (FPS) made up of 37 pins arranged in a hexagonal wrapped lattice with a pitch diameter ratio of 1.8. Along the FPS active length, three sections were instrumented to monitor the heat transfer coefficient along the bundle as well as the cladding temperatures at different ranks of the sub-channels. This paper reports the experimental data as well as a preliminary analysis and discussion of the results, focusing on the most relevant tests of the campaign, namely Test I (48 h) and Test II (97 h). Temperatures along three sections of the FPS and at inlet and outlet sections of the main components were reported and the Nusselt number in the FPS sub-channels was investigated together with the void fraction in the riser. Concerning the investigation of in-pool thermal stratification phenomena, the temperatures in the whole LBE pool were monitored at different elevations and radial locations. The analysis of experimental data obtained from Tests I and II underline the occurrence of thermal stratification phenomena in the region placed between the outlet sections of

  16. Modeling and optimization of fluoride and cadmium trapping in phosphogypsum using design methodology

    Energy Technology Data Exchange (ETDEWEB)

    Hajem, Besma; Djebali, Kais; M' nif, Adel [Laboratoire de Valorisation des Ressources Naturelles et des Materiaux de Recuperation, Centre National de Recherches en Sciences des Materiaux, Pole Technologique de Borj Cedria, Hammam Lif (Tunisia)

    2010-09-15

    The manufacturing of phosphoric acid from natural calcium phosphate generates a solid residue containing 25-30% humidity. This solid residue (phosphogypsum) generates acidic solution (pH {approx} 2.5) containing several toxic ionic species, that coat its grains. Fluorides and heavy metals such as cadmium are considered the most harmful species contained in the released solution from phosphogypsum. The purpose of this work is to study the trapping of fluorides and cadmium in phosphogypsum as well as effluent neutralization before its discharge into natural recipient. Therefore, calcium carbonate finely ground was added and fully mixed with wet phosphogypsum. A four factors central composite design was used to model and to optimize the operating parameters that govern the process. The studied factors were temperature, reaction time, mass, and grains size of CaCO{sub 3}. Considered responses were pH, F{sup -}, and Cd{sup 2+} concentrations in the released solution after reaction with CaCO{sub 3}. The optimum operating conditions were quite efficient to trap, respectively, 99% Cd{sup 2+} and 97% of F{sup -} with a final pH of 6.66. So an original, easy, simple, and cost effective method to trap some toxic species on phosphogypsum through CaCO{sub 3} addition would likely to be integrated in phosphoric acid manufacturing plant. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  17. Fluoride Content in Alcoholic Drinks.

    Science.gov (United States)

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

    2016-06-01

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

  18. Conformational diversity of flexible ligand in metal-organic frameworks controlled by size-matching mixed ligands

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Xiu-Ni; Qin, Lan; Yan, Xiao-Zhi; Yu, Lei; Xie, Yi-Xin; Han, Lei, E-mail: hanlei@nbu.edu.cn

    2015-12-15

    Hydrothermal reactions of N-auxiliary flexible exo-bidentate ligand 1,3-bis(4-pyridyl)propane (bpp) and carboxylates ligands naphthalene-2,6-dicarboxylic acid (2,6-H{sub 2}ndc) or 4,4′-(hydroxymethylene)dibenzoic acid (H{sub 2}hmdb), in the presence of cadmium(II) salts have given rise to two novel metal-organic frameworks based on flexible ligands (FL-MOFs), namely, [Cd{sub 2}(2,6-ndc){sub 2}(bpp)(DMF)]·2DMF (1) and [Cd{sub 3}(hmdb){sub 3}(bpp)]·2DMF·2EtOH (2) (DMF=N,N-Dimethylformamide). Single-crystal X-ray diffraction analyses revealed that compound 1 exhibits a three-dimensional self-penetrating 6-connected framework based on dinuclear cluster second building unit. Compound 2 displays an infinite three-dimensional ‘Lucky Clover’ shape (2,10)-connected network based on the trinuclear cluster and V-shaped organic linkers. The flexible bpp ligand displays different conformations in 1 and 2, which are successfully controlled by size-matching mixed ligands during the self-assembly process. - Graphical abstract: Compound 1 exhibits a 3D self-penetrating 6-connected framework based on dinuclear cluster, and 2 displays an infinite 3D ‘Lucky Clover’ shape (2,10)-connected network based on the trinuclear cluster. The flexible 1,3-bis(4-pyridyl)propane ligand displays different conformations in 1 and 2, which successfully controlled by size-matching mixed ligands during the self-assembly process.

  19. Ferroelectric fluoride compositions and methods of making and using same

    Science.gov (United States)

    Halasyamani, P Shiv; Chang, Hong-Young

    2015-04-07

    A method for synthesis of a ferroelectric material characterized by the general formula A.sub.xB.sub.yF.sub.z where A is an alkaline earth metal, B is transition metal or a main group metal, x and y each range from about 1 to about 5, and z ranges from about 1 to about 20 comprising contacting an alkaline earth metal fluoride, a difluorometal compound and a fluoroorganic acid in a medium to form a reaction mixture; and subjecting the reaction mixture to conditions suitable for hydrothermal crystal growth.

  20. From sequential to one-pot synthesis of dipyrrin based grid-type mixed metal-organic frameworks.

    Science.gov (United States)

    Béziau, Antoine; Baudron, Stéphane A; Fluck, Audrey; Hosseini, Mir Wais

    2013-12-16

    Both sequential and one-pot strategies for the preparation of a series of grid-type mixed metal-organic frameworks (MM'MOFs) based on dipyrrin ligands appended with either a pyridyl or a phenyl-imidazolyl moiety have been investigated. For the stepwise approach, the differentiation between the two coordination sites (nature, charge, and denticity) was exploited for the synthesis of a family of five discrete Zn(II), Cu(II), and Pd(II) complexes. Acting as metallatectons, these construction building blocks lead to the formation of a series of MM'MOFs upon self-assembly with CdCl2. In these rhombic grid-type architectures, four consecutive metallatectons are bridged by Cd(II) cations adopting an octahedral coordination geometry with the chloride anions occupying apical positions, thus behaving as square nodes. The shape of the rhombus grids as well as the way they are packed (stacking or interpenetration) in the crystalline phase are controlled by the nature of metallatectons and the solvent molecules present in the crystals. Consequently, the heterometallic assemblies display different accessible voids, although they are built on layers with the same connectivity. More interestingly, as demonstrated by X-ray diffraction on both single crystals and microcrystalline powders, the same MM'MOFs were obtained by a one-pot strategy through direct combinations of dipyrrin derivatives with the corresponding metal salts. This one-pot approach is efficient and more convenient than the sequential alternative, since the isolation, purification, and characterization of the, sometimes insoluble, metallatectons are not required.

  1. Fluoride inhibition of Sporosarcina pasteurii urease: structure and thermodynamics.

    Science.gov (United States)

    Benini, Stefano; Cianci, Michele; Mazzei, Luca; Ciurli, Stefano

    2014-12-01

    Urease is a nickel-dependent enzyme and a virulence factor for ureolytic bacterial human pathogens, but it is also necessary to convert urea, the most worldwide used fertilizer, into forms of nitrogen that can be taken up by crop plants. A strategy to control the activity of urease for medical and agricultural applications is to use enzyme inhibitors. Fluoride is a known urease inhibitor, but the structural basis of its mode of inhibition is still undetermined. Here, kinetic studies on the fluoride-induced inhibition of urease from Sporosarcina pasteurii, a widespread and highly ureolytic soil bacterium, were performed using isothermal titration calorimetry and revealed a mixed competitive and uncompetitive mechanism. The pH dependence of the inhibition constants, investigated in the 6.5-8.0 range, reveals a predominant uncompetitive mechanism that increases by increasing the pH, and a lesser competitive inhibition that increases by lowering the pH. Ten crystal structures of the enzyme were independently determined using five crystals of the native form and five crystals of the protein crystallized in the presence of fluoride. The analysis of these structures revealed the presence of two fluoride anions coordinated to the Ni(II) ions in the active site, in terminal and bridging positions. The present study consistently supports an interaction of fluoride with the nickel centers in the urease active site in which one fluoride competitively binds to the Ni(II) ion proposed to coordinate urea in the initial step of the catalytic mechanism, while another fluoride uncompetitively substitutes the Ni(II)-bridging hydroxide, blocking its nucleophilic attack on urea.

  2. Molecular anions sputtered from fluorides

    CERN Document Server

    Gnaser, H

    2002-01-01

    The emission of negatively charged ions from different fluoride samples (LiF, CaF sub 2 , LaF sub 3 and HfF sub 4) induced by sputtering with a 14.5-keV Cs sup + ion beam was studied. Sputtered ions were detected in a high-sensitivity double-focusing mass spectrometer. In particular, the possible existence of small doubly charged negative molecular ions was investigated. But whereas singly charged species of the general type MF sub n sup - (where M represents a metal atom) were detected with high abundances, stable dianions were observed in an unambiguous way only for one molecule: HfF sub 6 sup 2 sup -. The flight time through the mass spectrometer of approx 35 mu s establishes a lower limit with respect to the intrinsic lifetime of this doubly charged ion. For singly charged anions abundance distributions and, in selected cases, emission-energy spectra were recorded. For two ion species (Ca sup - and HfF sub 5 sup -) isotopic fractionation effects caused by the (velocity dependent) ionization process were d...

  3. Topical fluoride for caries prevention

    Science.gov (United States)

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

    2015-01-01

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

  4. 125 million Yuan has been In-vested in the Aluminium Fluoride Project in Mianchi County,He-nan Province

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>In May this year,Orient Shaoxing Salt Fluoride Co.,Ltd.under China Nonferrous Metals Min- ing Co.,Ltd.launched its 60,000-ton dry- process aluminium fluoride project.Currently, a total of 125 million Yuan has been invested in this project.It is reported that the project,lo-

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

    Science.gov (United States)

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

    2011-01-01

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

  6. On the origin of multi-component bulk metallic glasses: Atomic size mismatches and de-mixing

    Science.gov (United States)

    Zhang, Kai; Dice, Bradley; Liu, Yanhui; Schroers, Jan; Shattuck, Mark D.; O'Hern, Corey S.

    2015-08-01

    The likelihood that an undercooled liquid vitrifies or crystallizes depends on the cooling rate R . The critical cooling rate R c , below which the liquid crystallizes upon cooling, characterizes the glass-forming ability (GFA) of the system. While pure metals are typically poor glass formers with R c > 1 0 12 K/s , specific multi-component alloys can form bulk metallic glasses (BMGs) even at cooling rates below R ˜ 1 K / s . Conventional wisdom asserts that metal alloys with three or more components are better glass formers (with smaller R c ) than binary alloys. However, there is currently no theoretical framework that provides quantitative predictions for R c for multi-component alloys. In this manuscript, we perform simulations of ternary hard-sphere systems, which have been shown to be accurate models for the glass-forming ability of BMGs, to understand the roles of geometric frustration and demixing in determining R c . Specifically, we compress ternary hard sphere mixtures into jammed packings and measure the critical compression rate, below which the system crystallizes, as a function of the diameter ratios σB/σA and σC/σA and number fractions xA, xB, and xC. We find two distinct regimes for the GFA in parameter space for ternary hard spheres. When the diameter ratios are close to 1, such that the largest (A) and smallest (C) species are well-mixed, the GFA of ternary systems is no better than that of the optimal binary glass former. However, when σC/σA ≲ 0.8 is below the demixing threshold for binary systems, adding a third component B with σC < σB < σA increases the GFA of the system by preventing demixing of A and C. Analysis of the available data from experimental studies indicates that most ternary BMGs are below the binary demixing threshold with σC/σA < 0.8.

  7. Nanosheets of Two-Dimensional Magnetic and Conducting Fe(II)/Fe(III) Mixed-Valence Metal-Organic Frameworks.

    Science.gov (United States)

    Benmansour, Samia; Abhervé, Alexandre; Gómez-Claramunt, Patricia; Vallés-García, Cristina; Gómez-García, Carlos J

    2017-08-09

    We report the synthesis, magnetic properties, electrical conductivity, and delamination into thin nanosheets of two anilato-based Fe(II)/Fe(III) mixed-valence two-dimensional metal-organic frameworks (MOFs). Compounds [(H3O)(H2O)(phenazine)3][Fe(II)Fe(III)(C6O4X2)3]·12H2O [X = Cl (1) and Br (2)] present a honeycomb layered structure with an eclipsed packing that generates hexagonal channels containing the water molecules. Both compounds show ferrimagnetic ordering at ca. 2 K coexisting with electrical conductivity (with room temperature conductivities of 0.03 and 0.003 S/cm). Changing the X group from Cl to Br leads to a decrease in the ordering temperature and room temperature conductivity that is correlated with the decrease of the electronegativity of X. Despite the ionic charge of the anilato-based layers, these MOFs can be easily delaminated in thin nanosheets with the thickness of a few monolayers.

  8. Palladium mixed-metal surface-modified AB5-type intermetallides enhance hydrogen sorption kinetics

    Directory of Open Access Journals (Sweden)

    Roman V. Denys

    2010-09-01

    Full Text Available Surface engineering approaches were adopted in the preparation of advanced hydrogen sorption materials, based on ‘low-temperature’, AB5-type intermetallides. The approaches investigated included micro-encapsulation with palladium and mixed-metal mantles using electroless plating. The influence of micro-encapsulation on the surface morphology and kinetics of hydrogen charging were investigated. It was found that palladium-nickel (Pd-Ni co-deposition by electroless plating significantly improved the kinetics of hydrogen charging of the AB5-type intermetallides at low hydrogen pressure and temperature, after long-term pre-exposure to air. The improvement in the kinetics of hydrogen charging was credited to a synergistic effect between the palladium and nickel atoms in the catalytic mantle and the formation of an ‘interfacial bridge’ for hydrogen diffusion by the nickel atoms in the deposited layer. The developed surface-modified materials may find application in highly selective hydrogen extraction, purification, and storage from impure hydrogen feeds.

  9. Metal-organic framework mixed-matrix disks: Versatile supports for automated solid-phase extraction prior to chromatographic separation.

    Science.gov (United States)

    Ghani, Milad; Font Picó, Maria Francesca; Salehinia, Shima; Palomino Cabello, Carlos; Maya, Fernando; Berlier, Gloria; Saraji, Mohammad; Cerdà, Víctor; Turnes Palomino, Gemma

    2017-03-10

    We present for the first time the application of metal-organic framework (MOF) mixed-matrix disks (MMD) for the automated flow-through solid-phase extraction (SPE) of environmental pollutants. Zirconium terephthalate UiO-66 and UiO-66-NH2 MOFs with different size (90, 200 and 300nm) have been incorporated into mechanically stable polyvinylidene difluoride (PVDF) disks. The performance of the MOF-MMDs for automated SPE of seven substituted phenols prior to HPLC analysis has been evaluated using the sequential injection analysis technique. MOF-MMDs enabled the simultaneous extraction of phenols with the concomitant size exclusion of molecules of larger size. The best extraction performance was obtained using a MOF-MMD containing 90nm UiO-66-NH2 crystals. Using the selected MOF-MMD, detection limits ranging from 0.1 to 0.2μgL(-1) were obtained. Relative standard deviations ranged from 3.9 to 5.3% intra-day, and 4.7-5.7% inter-day. Membrane batch-to-batch reproducibility was from 5.2 to 6.4%. Three different groundwater samples were analyzed with the proposed method using MOF-MMDs, obtaining recoveries ranging from 90 to 98% for all tested analytes.

  10. 3D Online Submicron Scale Observation of Mixed Metal Powder's Microstructure Evolution in High Temperature and Microwave Compound Fields

    Directory of Open Access Journals (Sweden)

    Dan Kang

    2014-01-01

    Full Text Available In order to study the influence on the mechanical properties caused by microstructure evolution of metal powder in extreme environment, 3D real-time observation of the microstructure evolution of Al-Ti mixed powder in high temperature and microwave compound fields was realized by using synchrotron radiation computerized topography (SR-CT technique; the spatial resolution was enhanced to 0.37 μm/pixel through the designed equipment and the introduction of excellent reconstruction method for the first time. The process of microstructure evolution during sintering was clearly distinguished from 2D and 3D reconstructed images. Typical sintering parameters such as sintering neck size, porosity, and particle size of the sample were presented for quantitative analysis of the influence on the mechanical properties and the sintering kinetics during microwave sintering. The neck size-time curve was obtained and the neck growth exponent was 7.3, which indicated that surface diffusion was the main diffusion mechanism; the reason was the eddy current loss induced by the external microwave fields providing an additional driving force for mass diffusion on the particle surface. From the reconstructed images and the curve of porosity and average particle size versus temperature, it was believed that the presence of liquid phase aluminum accelerated the densification and particle growth.

  11. Deterioration of yttria-stabilized zirconia by boron carbide alone or mixed with metallic or oxidized Fe, Cr, Zr mixtures

    Energy Technology Data Exchange (ETDEWEB)

    De Bremaecker, A., E-mail: adbremae@sckcen.be [Belgian Nuclear Research Center (SCK-CEN), NMS, Mol (Belgium); Ayrault, L., E-mail: laurent.ayrault@cea.fr [Institut de Radio-Protection et Sûreté Nucléaire/DPAM/SEMIC, Bât 702, CEN de Cadarache BP3, F-13115 Saint-Paul-lez-Durance (France); Clément, B. [Institut de Radio-Protection et Sûreté Nucléaire/DPAM/SEMIC, Bât 702, CEN de Cadarache BP3, F-13115 Saint-Paul-lez-Durance (France)

    2014-08-01

    In the frame of severe accident conditions (PHEBUS FPT3 test), different experiments were carried out on the interactions of 20% yttria-stabilized zirconia (YSZ) and 20% ceria-stab zirconia with boron carbide or its oxidation products (B{sub 2}O{sub 3}): either tests under steam between 1230° and 1700 °C with B{sub 4}C alone or B{sub 4}C mixed with metals, either tests under Ar with boron oxide present in a mixture of iron and chromium oxides. In all cases an interaction was observed with formation of intergranular yttrium borate. At 1700 °C boron oxide is able to “pump out” the Y stabiliser from the YSZ grains but also some trace elements (Ca and Al) and to form a eutectic containing YBO{sub 3} and yttrium calcium oxy-borate (YCOB). At the same time a substantial swelling (“bloating”) of the zirconia happens, qualitatively similar to the foaming of irradiated fuel in contact with a Zr-melt. In all samples the lowering of the Y (or Ce)-content in the YSZ grains is so sharp that in the interaction layers zirconia is no longer stabilized. This is important when YSZ is envisaged as simulant of UO{sub 2} or as inert matrix for Am-transmutation.

  12. Plasmon enhanced molecular absorption: A mixed quantum–classical description of supramolecular complexes attached to a metal nanoparticle

    Energy Technology Data Exchange (ETDEWEB)

    Megow, Jörg, E-mail: megow@physik.hu-berlin.de; May, Volkhard, E-mail: may@physik.hu-berlin.de

    2014-01-15

    Highlights: • Enhancement of molecular absorption was shown for J-aggregate-like coupling between molecules and MNP. • A large number of molecules is required in order to observe the molecular absorption. • Pheos Qx-band coupling to the plasmon resonance is hardly observable in the spectrum. - Abstract: The application of a mixed quantum–classical methodology for an investigation of single pheophorbide-a molecules (Pheos) and respective supramolecular complexes is continued to effects caused by a nearby placed metal nanoparticle (MNP). Therefore, the classical simulation of the molecular nuclear degrees of freedom is combined with a uniform quantum description of the molecular electronic excitations coupled to those of the MNP. To account for the short MNP plasmon life time the quantum dynamics of the electronic degrees of freedom is formulated in the framework of a system-bath theory. Linear absorption spectra are calculated for a spherical 14 nm diameter Au–MNP decorated with isolated Pheos or with P{sub 16} complexes formed by 16 Pheos. The spectra are analyzed with respect to the molecular orientation at the MNP surface. While all studies on P{sub 16} only account for the Pheo Q{sub y}-transition we also present data on the MNP induced change of the single Pheo Q{sub x}-absorption.

  13. 3D online submicron scale observation of mixed metal powder's microstructure evolution in high temperature and microwave compound fields.

    Science.gov (United States)

    Kang, Dan; Xu, Feng; Hu, Xiao-fang; Dong, Bo; Xiao, Yu; Xiao, Ti-qiao

    2014-01-01

    In order to study the influence on the mechanical properties caused by microstructure evolution of metal powder in extreme environment, 3D real-time observation of the microstructure evolution of Al-Ti mixed powder in high temperature and microwave compound fields was realized by using synchrotron radiation computerized topography (SR-CT) technique; the spatial resolution was enhanced to 0.37  μm/pixel through the designed equipment and the introduction of excellent reconstruction method for the first time. The process of microstructure evolution during sintering was clearly distinguished from 2D and 3D reconstructed images. Typical sintering parameters such as sintering neck size, porosity, and particle size of the sample were presented for quantitative analysis of the influence on the mechanical properties and the sintering kinetics during microwave sintering. The neck size-time curve was obtained and the neck growth exponent was 7.3, which indicated that surface diffusion was the main diffusion mechanism; the reason was the eddy current loss induced by the external microwave fields providing an additional driving force for mass diffusion on the particle surface. From the reconstructed images and the curve of porosity and average particle size versus temperature, it was believed that the presence of liquid phase aluminum accelerated the densification and particle growth.

  14. Mixed ligand complexes of essential metal ions with L-glutamine and succinic acid in SLS-water mixtures

    Directory of Open Access Journals (Sweden)

    Bindu Hima Gandham

    2012-01-01

    Full Text Available Speciation of mixed ligand complexes of Co(II, Ni(II and Cu(II with L-glutamine and succinic acid was studied in varying amounts (0.0-2.5% w/v of sodium lauryl sulphate in aqueous solutions maintaining an ionic strength of 0.16 mol L-1 (NaCl at 303.0 K. Titrations were carried out in the presence of different relative concentrations (M : L : X = 1 : 2 : 2, 1 : 4 : 2, 1 : 2 : 4 of metal (M to L-glutamine (L to succinic acid (X with sodium hydroxide. Stability constants of ternary complexes were refined with MINIQUAD75. The best-fit chemical models were selected based on statistical parameters and residual analysis. The species detected were ML2X, MLX, MLXH and MLXH2 for Co(II, Ni(II and Cu(II. Extra stability of ternary complexes compared to their binary complexes was believed to be due to electrostatic interactions of the side chains of ligands, charge neutralization, chelate effect, stacking interactions and hydrogen bonding. The species distribution with pH at different compositions of SLS and plausible equilibria for the formation of species were also presented.

  15. Deterioration of yttria-stabilized zirconia by boron carbide alone or mixed with metallic or oxidized Fe, Cr, Zr mixtures

    Science.gov (United States)

    De Bremaecker, A.; Ayrault, L.; Clément, B.

    2014-08-01

    In the frame of severe accident conditions (PHEBUS FPT3 test), different experiments were carried out on the interactions of 20% yttria-stabilized zirconia (YSZ) and 20% ceria-stab zirconia with boron carbide or its oxidation products (B2O3): either tests under steam between 1230° and 1700 °C with B4C alone or B4C mixed with metals, either tests under Ar with boron oxide present in a mixture of iron and chromium oxides. In all cases an interaction was observed with formation of intergranular yttrium borate. At 1700 °C boron oxide is able to “pump out” the Y stabiliser from the YSZ grains but also some trace elements (Ca and Al) and to form a eutectic containing YBO3 and yttrium calcium oxy-borate (YCOB). At the same time a substantial swelling (“bloating”) of the zirconia happens, qualitatively similar to the foaming of irradiated fuel in contact with a Zr-melt. In all samples the lowering of the Y (or Ce)-content in the YSZ grains is so sharp that in the interaction layers zirconia is no longer stabilized. This is important when YSZ is envisaged as simulant of UO2 or as inert matrix for Am-transmutation.

  16. Carbon dioxide adsorption in amine-functionalized mixed-ligand metal-organic frameworks of UiO-66 topology.

    Science.gov (United States)

    Ethiraj, Jayashree; Albanese, Elisa; Civalleri, Bartolomeo; Vitillo, Jenny G; Bonino, Francesca; Chavan, Sachin; Shearer, Greig C; Lillerud, Karl Petter; Bordiga, Silvia

    2014-12-01

    A series of mixed-ligand [1,4-benzenedicarboxylic acid (BDC)/2-amino-1,4-benzenedicarboxylic acid (ABDC)] UiO-66 metal-organic frameworks (MOFs) synthesized through two different methods (low (LT) and high temperature (HT)) have been investigated for their carbon dioxide adsorption properties from 0 to 1 bar to clarify the role of amino loading on carbon dioxide uptake. Volumetric CO2 isotherms show that the CO2 capacity (normalized to the Langmuir surface area) increases with a degree of functionalization of about 46%; for similar NH2 contents, the same values are found for both synthetic procedures. Microcalorimetric isotherms reveal that amino-functionalized materials have a larger differential heat of adsorption (q(diff) ) towards CO2 ; reaching 27(25) and 20(22) kJ mol(-1) on HT(LT)-UiO-66-NH2 and UiO-66, respectively, at the lowest equilibrium pressures used in this study. All experimental results are supported by values obtained through quantum mechanical calculations.

  17. 49 CFR 173.163 - Hydrogen fluoride.

    Science.gov (United States)

    2010-10-01

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

  18. Growth of fluoride treated Kalanchoe pinnata plants

    Energy Technology Data Exchange (ETDEWEB)

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

    1962-01-01

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

  19. From Mixed-Metal MOFs to Carbon-Coated Core-Shell Metal Alloy@Metal Oxide Solid Solutions: Transformation of Co/Ni-MOF-74 to CoxNi1-x@CoyNi1-yO@C for the Oxygen Evolution Reaction.

    Science.gov (United States)

    Sun, Dengrong; Ye, Lin; Sun, Fangxiang; García, Hermenegildo; Li, Zhaohui

    2017-05-01

    Calcination of the mixed-metal species Co/Ni-MOF-74 leads to the formation of carbon-coated CoxNi1-x@CoyNi1-yO with a metal core diameter of ∼3.2 nm and a metal oxide shell thickness of ∼2.4 nm embedded uniformly in the ligand-derived carbon matrix. The close proximity of Co and Ni in the mixed-metal Co/Ni-MOF-74 promotes the metal alloying and the formation of a solid solution of metal oxide during the calcination process. The presence of the tightly coated carbon shell prohibits particle agglomeration and stabilizes the CoxNi1-x@CoyNi1-yO nanoparticles in small size. The CoxNi1-x@CoyNi1-yO@C derived from Co/Ni-MOF-74 nanocomposites show superior performance for the oxygen evolution reaction (OER). The use of mixed-metal MOFs as precursors represents a powerful strategy for the fabrication of metal alloy@metal oxide solid solution nanoparticles in small size. This method also holds great promise in the development of multifunctional carbon-coated complex core-shell metal/metal oxides owing to the diversified MOF structures and their flexible chemistry.

  20. Fluoride-induced chronic renal failure.

    Science.gov (United States)

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

    1987-08-01

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

  1. High-temperature thermochemical energy storage based on redox reactions using Co-Fe and Mn-Fe mixed metal oxides

    Science.gov (United States)

    André, Laurie; Abanades, Stéphane; Cassayre, Laurent

    2017-09-01

    Metal oxides are potential materials for thermochemical heat storage via reversible endothermal/exothermal redox reactions, and among them, cobalt oxide and manganese oxide are attracting attention. The synthesis of mixed oxides is considered as a way to answer the drawbacks of pure metal oxides, such as slow reaction kinetics, loss-in-capacity over cycles or sintering issues, and the materials potential for thermochemical heat storage application needs to be assessed. This work proposes a study combining thermodynamic calculations and experimental measurements by simultaneous thermogravimetric analysis and calorimetry, in order to identify the impact of iron oxide addition to Co and Mn-based oxides. Fe addition decreased the redox activity and energy storage capacity of Co3O4/CoO, whereas the reaction rate, reversibility and cycling stability of Mn2O3/Mn3O4 was significantly enhanced with added Fe amounts above 15 mol%, and the energy storage capacity was slightly improved. The formation of a reactive cubic spinel explained the improved re-oxidation yield of Mn-based oxides that could be cycled between bixbyite and cubic spinel phases, whereas a low reactive tetragonal spinel phase showing poor re-oxidation was formed below 15 mol% Fe. Thermodynamic equilibrium calculations predict accurately the behavior of both systems. The possibility to identify other suitable mixed oxides becomes conceivable, by enabling the selection of transition metal additives for tuning the redox properties of mixed metal oxides destined for thermochemical energy storage applications.

  2. First stars IX -Mixing in extremely metal-poor giants. Variation of the 12C/13C, [Na/Mg] and [Al/Mg] ratios

    CERN Document Server

    Spite, M; Hill, V; Spite, F; François, P; Plez, B; Bonifacio, P; Molaro, P; Depagne, E; Andersen, J; Barbuy, B; Beers, T C; Nordström, B; Primas, F

    2006-01-01

    Extremely metal-poor (EMP) stars preserve a fossil record of the composition of the ISM when the Galaxy formed. It is crucial, however, to verify whether internal mixing has modified their surface. We aim to understand the CNO abundance variations found in some, but not all EMP field giants analysed earlier. Mixing beyond the first dredge-up of standard models is required, and its origin needs clarification.The 12C/13C ratio is the most robust diagnostic of deep mixing, because it is insensitive to the adopted stellar parameters and should be uniformly high in near-primordial gas. We have measured 12C and 13C abundances in 35 EMP giants from high-quality VLT/UVES spectra. Correlations with other abundance data are used to study the depth of mixing.The 12C/13C ratio is found to correlate with [C/Fe] (and Li/H), and clearly anti-correlate with [N/Fe]. Evidence for such deep mixing is observed in giants above log L/Lsolar = 2.6, brighter than in less metal-poor stars, but matching the bump in the luminosity func...

  3. Portland Water Fluoridation: A Newspaper Analysis.

    Science.gov (United States)

    Bianchi, Allison; Bergren, Martha Dewey; Lewis, Patricia Ryan

    2017-03-01

    Portland, Oregon is the largest city in the United States without community water fluoridation (CWF). A newspaper analysis was conducted of the failed 2013 CWF campaign to evaluate anti-fluoridation and pro-fluoridation messaging provided by newspapers during the campaign. News content was categorized by type and slant (pro-fluoridation, anti-fluoridation, or neutral) and 34 variables were tabulated (23 anti-fluoridation, 11 pro-fluoridation). Results showed overall messaging was slightly pro-fluoridation, as compared to anti-fluoridation or neutral content (35%, 32%, and 33% respectively). Editorial content was 85% pro-fluoridation and 15% anti-fluoridation. The most frequent anti-fluoridation variables were alternatives to water fluoridation, mass/forced medication and concerns about the political process. Conversely, tooth decay and social justice were the most commonly cited pro-fluoridation variables. Newspapers can be influential in shaping public policy opinions in the fight for community water fluoridation. © 2016 Wiley Periodicals, Inc.

  4. Fluorination utilizing thermodynamically unstable fluorides and fluoride salts thereof

    Energy Technology Data Exchange (ETDEWEB)

    Bartlett, Neil (Orinda, CA); Whalen, J. Marc (Corning, NY); Chacon, Lisa (Corning, NY)

    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. Estimated Fluoride Doses from Toothpastes Should be Based on Total Soluble Fluoride

    OpenAIRE

    Cury,Jaime A.; Saul M Paiva; Tenuta,Livia M.A; Oliveira,Maria José L.; Martins, Carolina C.

    2013-01-01

    The fluoride dose ingested by young children may be overestimated if based on levels of total fluoride (TF) rather than levels of bioavailable fluoride (total soluble fluoride-TSF) in toothpaste. The aim of the present study was to compare doses of fluoride intake based on TF and TSF. Fluoride intake in 158 Brazilian children aged three and four years was determined after tooth brushing with their usual toothpaste (either family toothpaste (n = 80) or children's toothpaste (n = 78)). The esti...

  6. Investigating the Intercalation Chemistry of Alkali Ions in Fluoride Perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Tanghong; Chen, Wei; Cheng, Lei; Bayliss, Ryan D.; Lin, Feng; Plews, Michael R.; Nordlund, Dennis; Doeff, Marca M.; Persson, Kristin A.; Cabana, Jordi

    2017-02-07

    Reversible intercalation reactions provide the basis for modern battery electrodes. Despite decades of exploration of electrode materials, the potential for materials in the nonoxide chemical space with regards to intercalation chemistry is vast and rather untested. Transition metal fluorides stand out as an obvious target. To this end, we report herein a new family of iron fluoride-based perovskite cathode materials AxK1–xFeF3 (A = Li, Na). By starting with KFeF3, approximately 75% of K+ ions were subsequently replaced by Li+ and Na+ through electrochemical means. X-ray diffraction and Fe X-ray absorption spectroscopy confirmed the existence of intercalation of alkali metal ions in the perovskite structure, which is associated with the Fe2+/3+ redox couple. A computational study by density functional theory showed agreement with the structural and electrochemical data obtained experimentally, which suggested the possibility of fluoride-based materials as potential intercalation electrodes. This study increases our understanding of the intercalation chemistry of ternary fluorides, which could inform efforts toward the exploration of new electrode materials.

  7. Screening biological traits and fluoride contents of native vegetations in arid environments to select efficiently fluoride-tolerant native plant species for in-situ phytoremediation.

    Science.gov (United States)

    Boukhris, Asma; Laffont-Schwob, Isabelle; Mezghani, Imed; El Kadri, Lefi; Prudent, Pascale; Pricop, Anca; Tatoni, Thierry; Chaieb, Mohamed

    2015-01-01

    High fluoride pollution has been detected in the surrounding soils of the coastal superphosphate industries in the Gulf of Gabes (Southeast of Tunisia). A study was conducted in vicinity of factories analysing plant functional traits combined with plant fluoride accumulation and soil metal concentrations aiming to screen more efficiently native plant species tolerant to this pollution. Aerial parts of 18 plant species out of the 10 most abundant species per site were harvested on two polluted sites of Gabes and Skhira at the vicinity of the factories and on the less polluted site of Smara. Native plant species accumulated fluoride following the gradient of soil pollution. Fluoride contents of plant aerial parts ranged from 37 mg kg(-1) to 360 mg kg(-1) and five plant species were only found in the most polluted site. However these latter had low biomass and soil cover. Crossing biological traits and fluoride contents, a selection grid for potentially restorative plant species enabled the selection of three native perennials i.e. Rhanterium suaveolens, Atractylis serratuloides and, Erodium glaucophyllum as potential candidates for an in-situ phytoremediation program on arid fluoride-polluted sites. This approach may be used in other fluoride-polluted Mediterranean environments.

  8. Nickel, cobalt, chromium, palladium and gold induce a mixed Th1- and Th2-type cytokine response in vitro in subjects with contact allergy to the respective metals.

    Science.gov (United States)

    Minang, J T; Areström, I; Troye-Blomberg, M; Lundeberg, L; Ahlborg, N

    2006-12-01

    Nickel (Ni), the main cause of contact allergy to metals, induces in vitro production of both Th1- and Th2-type cytokines in peripheral blood mononuclear cells (PBMC) from allergic subjects. Because the knowledge of the cellular immune response to other metals involved in contact allergy has been limited, we investigated the cytokine profile induced by Ni, cobalt (Co), chromium (Cr), palladium (Pd) and gold (Au) in PBMC from patients with patch test reactivity to the respective metals. PBMC from patients with patch test reactivity to Ni, Co, Cr, Au and/or Pd (n = 31) and non-allergic controls (n = 5) were stimulated in vitro with corresponding metal salts. Th1- [interleukin (IL)-2 and interferon (IFN)-gamma] and Th2- (IL-4 and IL-13) type cytokine responses were measured by enzyme-linked immunospot (ELISpot) and/or enzyme-linked immunosorbent assay (ELISA). All metals induced a mixed Th1- and Th2-type cytokine production in PBMC from individual patients with patch test reactivity to the corresponding metal, but not in control PBMC. Significantly higher responses in the patient versus controls were found for Cr (IL-2 and IL-13), Pd (IL-2 and IL-4), Au (IL-13 and IFN-gamma) (all P reactivities to metals, respectively, were matched by the in vitro reactivity. In conclusion, our data suggest that sensitization to Co, Cr, Pd and Au results in a cellular immune response of a character similar to the mixed Th1- and Th2-type cytokine profile shown previously to be induced by Ni.

  9. Hydride reactivity of Ni(II)-X-Ni(II) entities: mixed-valent hydrido complexes and reversible metal reduction.

    Science.gov (United States)

    Gehring, Henrike; Metzinger, Ramona; Herwig, Christian; Intemann, Julia; Harder, Sjoerd; Limberg, Christian

    2013-01-28

    After the lithiation of PYR-H(2) (PYR(2-) =[{NC(Me)C(H)C(Me)NC(6)H(3)(iPr)(2)}(2)(C(5)H(3)N)](2-)), which is the precursor of an expanded β-diketiminato ligand system with two binding pockets, its reaction with [NiBr(2) (dme)] led to a dinuclear nickel(II)-bromide complex, [(PYR)Ni(μ-Br)NiBr] (1). The bridging bromide ligand could be selectively exchanged for a thiolate ligand to yield [(PYR)Ni(μ-SEt)NiBr] (3). In an attempt to introduce hydride ligands, both compounds were treated with KHBEt(3). This treatment afforded [(PYR)Ni(μ-H)Ni] (2), which is a mixed valent Ni(I)-μ-H-Ni(II) complex, and [(PYR-H)Ni(μ-SEt)Ni] (4), in which two tricoordinated Ni(I) moieties are strongly antiferromagnetically coupled. Compound 4 is the product of an initial salt metathesis, followed by an intramolecular redox process that separates the original hydride ligand into two electrons, which reduce the metal centres, and a proton, which is trapped by one of the binding pockets, thereby converting it into an olefin ligand on one of the Ni(I) centres. The addition of a mild acid to complex 4 leads to the elimination of H(2) and the formation of a Ni(II)Ni(II) compound, [(PYR)Ni(μ-SEt)NiOTf] (5), so that the original Ni(II) (μ-SEt)Ni(II) X core of compound 3 is restored. All of these compounds were fully characterized, including by X-ray diffraction, and their molecular structures, as well as their formation processes, are discussed.

  10. Comparative Study of MIL-96(Al) as Continuous Metal-Organic Frameworks Layer and Mixed-Matrix Membrane.

    Science.gov (United States)

    Knebel, Alexander; Friebe, Sebastian; Bigall, Nadja Carola; Benzaqui, Marvin; Serre, Christian; Caro, Jürgen

    2016-03-23

    MIL-96(Al) layers were prepared as supported metal-organic frameworks membrane via reactive seeding using the α-alumina support as the Al source for the formation of the MIL-96(Al) seeds. Depending on the solvent mixture employed during seed formation, two different crystal morphologies, with different orientation of the transport-active channels, have been formed. This crystal orientation and habit is predefined by the seed crystals and is kept in the subsequent growth of the seeds to continuous layers. In the gas separation of an equimolar H2/CO2 mixture, the hydrogen permeability of the two supported MIL-96(Al) layers was found to be highly dependent on the crystal morphology and the accompanied channel orientation in the layer. In addition to the neat supported MIL-96(Al) membrane layers, mixed-matrix membranes (MMMs, 10 wt % filler loading) as a composite of MIL-96(Al) particles as filler in a continuous Matrimid polymer phase have been prepared. Five particle sizes of MIL-96(Al) between 3.2 μm and 55 nm were synthesized. In the preparation of the MIL-96(Al)/Matrimid MMM (10 wt % filler loading), the following preparation problems have been identified: The bigger micrometer-sized MIL-96(Al) crystals show a trend toward sedimentation during casting of the MMM, whereas for nanoparticles aggregation and recrystallization to micrometer-sized MIL-96(Al) crystals has been observed. Because of these preparation problems for MMM, the neat supported MIL-96(Al) layers show a relatively high H2/CO2 selectivity (≈9) and a hydrogen permeance approximately 2 magnitudes higher than that of the best MMM.

  11. Trace element composition and U-Pb age of zircons from Estherville: Constraints on the timing of the metal-silicate mixing event on the mesosiderite parent body

    Science.gov (United States)

    Haba, Makiko K.; Yamaguchi, Akira; Kagi, Hiroyuki; Nagao, Keisuke; Hidaka, Hiroshi

    2017-10-01

    Mesosiderites are a group of stony-iron meteorites, which are thought to be the result of mixing of silicates with Fe-Ni metal. In this study, we combined textural observations with geochemical and chronological studies of two zircon grains found in the Estherville mesosiderite. One of the zircons (Zrc1) occurs with pyroxene, plagioclase, troilite, and silica, and the other (Zrc2) is located at a boundary between Fe-Ni metal and a silicate part mainly composed of pyroxene and plagioclase. The textural observations demonstrate that Zrc1 is relatively homogenous, whereas Zrc2 is composed of at least two chemically distinct domains. Trace element analyses of Zrc2 resolve large concentration gradients within this single grain with variations that are an order of magnitude for rare earth elements (REE) and two orders of magnitude for U and Th. The lowest trace element concentration in Zrc2 is more than an order of magnitude lower than those of lunar and eucritic zircons. However, it is similar to those of Zrc1 and a zircon from the Vaca Muerta mesosiderite. The calculated REE composition of the melt in equilibrium with Zrc2 shows that Zrc2 and perhaps also Zrc1 did not crystallize from a melt that was produced by fractional crystallization of the primary magmatic mineral assemblages. The zircons with low REE, U, and Th concentrations can be interpreted to have formed in a residual melt after incorporation of large amounts of REE, U, and Th into secondary phosphate minerals, which formed during the metal-silicate mixing event. The large concentration gradients observed in Zrc2 suggest significant heterogeneities in the melt from which the zircon crystallized. Alternatively, either mixing or diffusion between a relict zircon and a newly formed zircon could explain the observed concentration gradients. However, the REE patterns of Zrc2 cannot be explained by mixing or diffusion between the two distinct generations of zircons. These considerations suggest that Zrc1 and Zrc2

  12. Metal-enhanced fluorescence of mixed coumarin dyes by silver and gold nanoparticles: Towards plasmonic thin-film luminescent solar concentrator

    Energy Technology Data Exchange (ETDEWEB)

    El-Bashir, S.M., E-mail: elbashireg@yahoo.com [Department of Physics and Astronomy, Science College, King Saud University, Riyadh, KSA (Saudi Arabia); Department of Physics Faculty of Science, Benha University (Egypt); Barakat, F.M.; AlSalhi, M.S. [Department of Physics and Astronomy, Science College, King Saud University, Riyadh, KSA (Saudi Arabia)

    2013-11-15

    Poly(methyl methacrylate) (PMMA) nanocomposite films doped with mixed coumarin dyestuffs and noble metal nanoparticles (60 nm silver and 100 nm gold) were prepared by spin coating technique. The effect of silver and gold nanoparticles on the film properties was studied by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV–vis absorption and fluorescence spectroscopy measurements. DSC measurements indicated the increase of the glass transition temperature of the films by increasing nanogold concentration, recommending their promising thermal stability towards hot climates. It was found that the fluorescence signals of the mixed coumarin dyes were amplified by 5.4 and 7.15 folds as a result of metal enhanced fluorescence (MEF). The research outcomes offered a potential application of these films in solar energy conversion by plasmonic thin film luminescent solar concentrator (PTLSC). -- Graphical abstract: Plasmonic thin film luminescent solar concentrators. Highlights: • Metal enhanced fluorescence was achieved for mixed coumarin dyes doped in PMMA nanocomposite films. • The amplification of the fluorescence signals is dependent on the concentration of silver and gold nanoparticles. • These films is considered as potential candidates for plasmonic thin film luminescent solar concentrators (PTLSCs)

  13. High-dielectric polymer composite materials from a series of mixed-metal phenylphosphonates, ATi(C6H5PO3)3 for dielectric energy storage.

    Science.gov (United States)

    Barber, Peter; Pellechia, Perry J; Ploehn, Harry J; zur Loye, H-C

    2010-09-01

    We report the preparation of new polymer composite dielectric materials for energy storage applications. New layered 1:1 mixed A+2/Ti4+ metal phenylphosphonates, ATi(O3PC6H5)3, A=Mg, Ca, Sr, Ba, and Pb, have been prepared via a melt route, in which mixed metal oxides, ATiO3, were reacted with molten phenyl phosphonic acid. The mixed-metal phosphonates were combined with polystyrene (PS) via a solution route and cast as thin films for dielectric permittivity measurements. The ATi(O3PC6H5)3-PS composites exhibit a substantial enhancement in the dielectric permittivity as a function of weight loading relative to the parent ATiO3-PS composites. For both ATiO3-PS and ATi(O3PC6H5)3-PS, the composites' dielectric permittivity increases with A cation polarizability. Unusually large increases for 40 wt% ATi(O3PC6H5)3-PS composites (A=Sr, Ba, and Pb) indicate permittivity enhancement that goes beyond the effect of varying filler composition.

  14. Mixed metal copper(II)-nickel(II) and copper(II)-zinc(II) complexes of multihistidine peptide fragments of human prion protein.

    Science.gov (United States)

    Jószai, Viktória; Turi, Ildikó; Kállay, Csilla; Pappalardo, Giuseppe; Di Natale, Giuseppe; Rizzarelli, Enrico; Sóvágó, Imre

    2012-07-01

    Mixed metal copper(II)-nickel(II) and copper(II)-zinc(II) complexes of four peptide fragments of human prion protein have been studied by potentiometric, UV-vis and circular dichroism spectroscopic techniques. One peptide contained three histidyl residues: HuPrP(84-114) with H85 inside and H96, H111 outside the octarepeat domain. The other three peptides contained two histidyl residues; H96 and H111 for HuPrP(91-115) and HuPrP(84-114)H85A while HuPrP(84-114)H96A contained the histidyl residues at positions 85 and 111. It was found that both histidines of the latter peptides can simultaneously bind copper(II) and nickel(II) ions and dinuclear mixed metal complexes can exist in slightly alkaline solution. One molecule of the peptide with three histidyl residues can bind two copper(II) and one nickel(II) ions. H85 and H111 were identified as the major copper(II) and H96 as the preferred nickel(II) binding sites in mixed metal species. The studies on the zinc(II)-PrP peptide binary systems revealed that zinc(II) ions can coordinate to the 31-mer PrP peptide fragments in the form of macrochelates with two or three coordinated imidazol-nitrogens but the low stability of these complexes cannot prevent the hydrolysis of the metal ion in slightly alkaline solution. These data provide further support for the outstanding affinity of copper(II) ions towards the peptide fragments of prion protein but the binding of nickel(II) can significantly modify the distribution of copper(II) among the available metal binding sites.

  15. Research on an FM/cw ladar system using a 64 × 64 InGaAs metal-semiconductor-metal self-mixing focal plane array of detectors.

    Science.gov (United States)

    Gao, Jian; Sun, Jianfeng; Cong, Mingyu

    2017-04-01

    Frequency-modulated/continuous-wave imaging systems are a focal plane array (FPA) ladar architecture that is applicable to smart munitions, reconnaissance, face recognition, robotic navigation, etc. In this paper, we report a 64×64 pixel FPA ladar system we built using a 1550 nm amplified laser diode transmitter and an InAlAs/InGaAs metal-semiconductor-metal self-mixing detector array and the test results attained over the years it was constructed. Finally, we gained 4D imaging (3D range + 1D intensity) of the target with the range of 220 m.

  16. An Overview of Liquid Fluoride Salt Heat Transport Systems

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-01

    Heat transport is central to all thermal-based forms of electricity generation. The ever increasing demand for higher thermal efficiency necessitates power generation cycles transitioning to progressively higher temperatures. Similarly, the desire to provide direct thermal coupling between heat sources and higher temperature chemical processes provides the underlying incentive to move toward higher temperature heat transfer loops. As the system temperature rises, the available materials and technology choices become progressively more limited. Superficially, fluoride salts at {approx}700 C resemble water at room temperature being optically transparent and having similar heat capacity, roughly three times the viscosity, and about twice the density. Fluoride salts are a leading candidate heat-transport material at high temperatures. Fluoride salts have been extensively used in specialized industrial processes for decades, yet they have not entered widespread deployment for general heat transport purposes. This report does not provide an exhaustive screening of potential heat transfer media and other high temperature liquids such as alkali metal carbonate eutectics or chloride salts may have economic or technological advantages. A particular advantage of fluoride salts is that the technology for their use is relatively mature as they were extensively studied during the 1940s-1970s as part of the U.S. Atomic Energy Commission's program to develop molten salt reactors (MSRs). However, the instrumentation, components, and practices for use of fluoride salts are not yet developed sufficiently for commercial implementation. This report provides an overview of the current understanding of the technologies involved in liquid salt heat transport (LSHT) along with providing references to the more detailed primary information resources. Much of the information presented here derives from the earlier MSR program. However, technology has evolved over the intervening years

  17. An Overview of Liquid Fluoride Salt Heat Transport Systems

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-01

    Heat transport is central to all thermal-based forms of electricity generation. The ever increasing demand for higher thermal efficiency necessitates power generation cycles transitioning to progressively higher temperatures. Similarly, the desire to provide direct thermal coupling between heat sources and higher temperature chemical processes provides the underlying incentive to move toward higher temperature heat transfer loops. As the system temperature rises, the available materials and technology choices become progressively more limited. Superficially, fluoride salts at {approx}700 C resemble water at room temperature being optically transparent and having similar heat capacity, roughly three times the viscosity, and about twice the density. Fluoride salts are a leading candidate heat-transport material at high temperatures. Fluoride salts have been extensively used in specialized industrial processes for decades, yet they have not entered widespread deployment for general heat transport purposes. This report does not provide an exhaustive screening of potential heat transfer media and other high temperature liquids such as alkali metal carbonate eutectics or chloride salts may have economic or technological advantages. A particular advantage of fluoride salts is that the technology for their use is relatively mature as they were extensively studied during the 1940s-1970s as part of the U.S. Atomic Energy Commission's program to develop molten salt reactors (MSRs). However, the instrumentation, components, and practices for use of fluoride salts are not yet developed sufficiently for commercial implementation. This report provides an overview of the current understanding of the technologies involved in liquid salt heat transport (LSHT) along with providing references to the more detailed primary information resources. Much of the information presented here derives from the earlier MSR program. However, technology has evolved over the intervening years

  18. Liquid-metal MHD energy conversion. Status report, March 1976--September 1977. [Coal combustion products are mixed with liquid copper and act as working fluid

    Energy Technology Data Exchange (ETDEWEB)

    Petrick, M; Dunn, P F; Pierson, E S; Dauzvardis, P V; Pollack, I

    1979-05-01

    A new open-cycle coal-fired liquid-metal MHD concept has been developed, in which the combustion products are mixed directly with liquid copper and the mixture is then passed through the MHD generator. This concept yields a system with an efficiency comparable to that of open-cycle plasma MHD at combustor temperatures as much as 1000 K lower and MHD generator temperatures more than 1000 K lower than is the case for open-cycle plasma MHD. Significantly, the liquid-metal system uses components that are close to or within present-day technology, and it appears that readily available containment materials are compatible with the fluids. The first commercial system studies for the liquid-metal Rankine-cycle concept show that it yields a higher conversion efficiency than conventional steam cycles for lower-temperature heat sources, such as a liquid-metal fast-breeder reactor, a light-water reactor, or solar collectors without any potential for hazardous reactions betweeen liquid metals (e.g., sodium) and water. Fabrication of the high-temperature liquid-metal MHD facility has been completed, and shakedown runs have been performed, using a substitute mixer-generator test section. Data obtained in this test section agreed well with existing single-phase and newly-developed two-phase correlations for the pressure gradient.

  19. An in vitro assessment of fluoride uptake by tooth enamel from four different fluoride dentifrices.

    Science.gov (United States)

    Patil, V H; Anegundi, R T

    2014-10-01

    The aim of this study was to evaluate fluoride uptake by tooth enamel with four different fluoride dentifrices. Sixty human premolars extracted for orthodontic purpose were selected for the study. The teeth were covered with nail varnish leaving a window of 4 × 4 mm on the enamel surface of the buccal and lingual sides. The teeth were demineralised and were divided into four groups with 15 teeth in each group. The buccal window served as experimental and the lingual as control. The teeth were immersed in toothpaste slurry containing: sodium fluoride (Group A); sodium monofluorophosphate (Group B); stannous fluoride (Group C) and amine fluoride (Group D). The fluoride content in the etched superficial enamel layer in the windows was analysed using a fluoride ion-specific electrode. Within the parameters of this study, the uptake of fluoride was statistically significant in Group D (p fluoride by tooth enamel in an increasing order was Group A fluoride had the highest fluoride uptake.

  20. Direct selenylation of mixed Ni/Fe metal-organic frameworks to NiFe-Se/C nanorods for overall water splitting

    Science.gov (United States)

    Xu, Bo; Yang, He; Yuan, Lincheng; Sun, Yiqiang; Chen, Zhiming; Li, Cuncheng

    2017-10-01

    Development of low-cost, highly active bifunctional catalyst for efficient overall water splitting based on earth-abundant metals is still a great challenging task. In this work, we report a NiFe-Se/C composite nanorod as efficient non-precious-metal electrochemical catalyst derived from direct selenylation of a mixed Ni/Fe metal-organic framework. The as-obtained catalyst requires low overpotential to drive 10 mA cm-2 for HER (160 mV) and OER (240 mV) in 1.0 M KOH, respectively, and its catalytic activity is maintained for at least 20 h. Moreover, water electrolysis using this catalyst achieves high water splitting current density of 10 mA cm-2 at cell voltage of 1.68 V.

  1. Separation of metallic residues from the dissolution of a high-burnup BWR fuel using nitrogen trifluoride

    Energy Technology Data Exchange (ETDEWEB)

    McNamara, Bruce K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Buck, Edgar C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Soderquist, Chuck Z. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Smith, Frances N. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Mausolf, Edward J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Scheele, Randall D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-03-23

    Nitrogen trifluoride (NF3) was used to fluorinate the metallic residue from the dissolution of a high burnup, boiling water reactor fuel (~70 MWd/kgU). The metallic residue included the noble metal phase (containing ruthenium, rhodium, palladium, technetium, and molybdenum), and smaller amounts of zirconium, selenium, tellurium, and silver. Exposing the noble metal phase to 10% NF3 in argon between 400 and 550°C, removed molybdenum and technetium near 400°C as their volatile fluorides, and ruthenium near 500C as its volatile fluoride. The events were thermally and temporally distinct and the conditions specified are a recipe to separate these transition metals from each other and from the noble metal phase nonvolatile residue. Depletion of the volatile fluorides resulted in substantial exothermicity. Thermal excursion behavior was recorded under non-adiabatic, isothermal conditions that typically minimize heat release. Physical characterization of the metallic noble phase and its thermal behavior are consistent with high kinetic velocity reactions encouraged by the nanoparticulate phase or perhaps catalytic influences of the mixed platinum metals with nearly pure phase structure. Post-fluorination, only two phases were present in the residual nonvolatile fraction. These were identified as a nano-crystalline, metallic palladium cubic phase and a hexagonal rhodium trifluoride (RhF3) phase. The two phases were distinct as the sub-µm crystallites of metallic palladium were in contrast to the RhF3 phase, which grew from the parent nano-crystalline noble-metal phase during fluorination, to acicular crystals exceeding 20-µm in length.

  2. Fluoride bioavailability in saliva and plaque

    Science.gov (United States)

    2012-01-01

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

  3. Studies of fluoride varnishes in Finland.

    Science.gov (United States)

    Seppä, L

    1991-01-01

    Despite the artificial fluoridation of drinking water in Kuopio, part of the children have high caries incidence. We therefore started our studies on fluoride varnishes in 1977 in an attempt to find a feasible means of applying fluoride topically in children at high risk of caries. In our first trial, the sodium fluoride varnish Duraphat was found to be effective in preventing caries, but the effectiveness of the silane fluoride varnish Fluor Protector could not be unequivocally established, despite the fact that Fluor Protector deposited markedly more fluoride in enamel than Duraphat. In a second study in children in a low-fluoride area, use of Duraphat was found to be more effective than fortnightly fluoride rinses or Fluor Protector. Increasing the frequency of application from two to four times a year did not increase the effectiveness of Duraphat even in highly caries-prone children in a 2-year trial. On the basis of peak values of fluoride in parotid saliva after application, use of either fluoride varnishes was considered safe. Although the fluoride content of the enamel remained elevated for at least two years after discontinuation of treatment with both varnishes, the caries preventive effect did not continue after the applications were stopped. This shows that increasing the fluoride content of enamel is not the main mechanism by which fluoride varnishes prevent caries, and that the applications need to be continued as long as caries is a problem.

  4. Chronic Fluoride Toxicity: Dental Fluorosis

    Science.gov (United States)

    DenBesten, Pamela; Li, Wu

    2012-01-01

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

  5. Chronic fluoride toxicity: dental fluorosis.

    Science.gov (United States)

    Denbesten, Pamela; Li, Wu

    2011-01-01

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

  6. Density functional investigation of metal-metal interactions in mixed-valence d2d3 (Cr, Mo, W) and d3d4 (Mn, Tc, Re) face-shared [M2Cl9]2- systems.

    Science.gov (United States)

    Cavigliasso, Germán; Comba, Peter; Stranger, Robert

    2004-10-18

    The molecular and electronic structures of mixed-valence face-shared (Cr, Mo, W) d(2)d(3) and (Mn, Tc, Re) d(3)d(4) [M(2)Cl(9)](2-) dimers have been calculated by density functional methods in order to investigate metal-metal bonding in this series. The electronic structures of these systems have been analyzed using potential energy curves for the broken-symmetry and other spin states arising from the d(2)d(3) and d(3)d(4) coupling modes. In (d(2)d(3)) [Mo(2)Cl(9)](2-) and [W(2)Cl(9)](2-), the global minimum has been found to be a spin-doublet state characterized by delocalization of the metal-based electrons in a multiple metal-metal bond (with a formal bond order of 2.5). In contrast, weak coupling between the metal centers and electron localization are favored in (d(2)d(3)) [Cr(2)Cl(9)](2-), the global minimum for this species being a ferromagnetic S = 5/2 state with a relatively long Cr-Cr separation. The (d(3)d(4)) [Re(2)Cl(9)](2-) system also exhibits a global minimum corresponding to a metal-metal bonded spin-doublet state with a formal bond order of 2.5, reflecting the electron-hole equivalence between d(2)d(3) and d(3)d(4) configurations. Double minima behavior is predicted for (d(3)d(4)) [Tc(2)Cl(9)](2-) and [Mn(2)Cl(9)](2-) due to two energetically close low-lying states (these being S = 3/2 and S = 5/2 states for the former, and S = 5/2 and S = 7/2 states for the latter). A comparison of computational results for the d(2)d(2), d(2)d(3), and d(3)d(3) [W(2)Cl(9)](z-) series and the d(3)d(3), d(3)d(4), and d(4)d(4) [Re(2)Cl(9)](z-) series indicates that the observed trends in metal-metal distances can only be rationalized if changes in both the strength of sigma bonding and metal-metal bond order are taken into consideration. These two factors act conjointly in the W series but in opposition to one another in the Re series. In the case of the [Cr(2)Cl(9)](z-) and [Mn(2)Cl(9)](z-) dimers, the metal-metal bond lengths are significantly shorter for mixed

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

    OpenAIRE

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

    2016-01-01

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

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

    NARCIS (Netherlands)

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

    1997-01-01

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

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

    NARCIS (Netherlands)

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

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

  10. Water Fluoridation Reporting System (Public Water Systems)

    Data.gov (United States)

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

  11. Fluoridering af drikkevandet i Danmark?

    DEFF Research Database (Denmark)

    Arvin, Erik; Spliid, Henrik; Bruvo, M.;

    2010-01-01

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

  12. First-principles molecular dynamics modeling of the molten fluoride salt with Cr solute

    Energy Technology Data Exchange (ETDEWEB)

    Nam, H.O.; Bengtson, A.; Vörtler, K.; Saha, S.; Sakidja, R.; Morgan, D., E-mail: ddmorgan@wisc.edu

    2014-06-01

    Fluoride salts and their interactions with metals are of wide interest for the nuclear community. In this work, first-principles molecular dynamics (FPMD) was employed to study both pure molten fluoride salt and fluoride salt with dissolved solute Cr ions (a common corrosion product) at high temperature (823–1423 K). Two types of molten fluoride salts, namely flibe (LiF–BeF{sub 2}) and flinak (LiF–NaF–KF), with the Cr{sup 0}, Cr{sup 2+} and Cr{sup 3+} ions were chosen as a target system for the FPMD modeling. The prediction of thermo-kinetic properties of pure fluoride salt, such as the equilibrium volume, density, bulk modulus, coefficient of thermal expansion, and self-diffusion coefficient, provide useful extensions of existing data and verify the accuracy of the FPMD simulation in modeling of fluoride salts. The FPMD modeling of solute Cr in fluoride salt shows the effect of Cr valence on diffusivity and local structure in the salt.

  13. Quinoxaline based bio-active mixed ligand transition metal complexes: Synthesis, characterization, electrochemical, antimicrobial, DNA binding, cleavage, antioxidant and molecular docking studies.

    Science.gov (United States)

    Dhanaraj, C Justin; Johnson, Jijo

    2015-10-01

    Co(II), Ni(II), Cu(II) and Zn(II) mixed ligand complexes have been synthesized from N(2), N(3)-bis(4-nitrophenyl)quinoxaline-2,3-diamine and 1,10-phenanthroline. The compounds were characterized by elemental analyses, molar conductance, magnetic susceptibility, IR, UV-Vis., (1)H NMR, mass and ESR spectra. Octahedral geometry has been assigned for Co(II), Ni(II) and Zn(II) complexes and distorted octahedral geometry for Cu(II) complex. Electrochemical behavior of the synthesized complexes was studied using cyclic voltammetry. Grain size and surface morphologies of the complexes were determined by powder XRD and SEM analyses. The mixed ligand metal complexes were screened for antimicrobial activity against bacterial species Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus; fungal species Aspergillus niger, and Candida albicans by disc diffusion method. The DNA binding and DNA cleavage activities of the compounds were determined using electronic absorption titration and agarose gel electrophoresis respectively. The superoxide radical scavenging and free radical scavenging activities of the Cu(II) complex was also evaluated. Molecular docking studies of the synthesized mixed ligand metal complexes were carried out against B-DNA dodecamer and the protein Plasmodium falciparum dihydrofolate reductase (pf DHFR).

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

    Energy Technology Data Exchange (ETDEWEB)

    Just, R.A.

    1988-01-01

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

  15. Synthesis of Fluoridated Hydroxyapatite Containing Potassium and Its Effect on Dentin

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The aim of this work was to produce a nanoscale fluoridated and potassium containing hydroxyapatite via sol-gel method and to observe the effect of occlusion of the dentin tubule under scanning electron microscopy. HF was selected as fluorine-containing reagent which was added into mixed Ca ( NO3 )2-P2 O5 ethanol solutions to obtain dipping sols. All of the resulting samples showed apatite structure in their X- ray diffraction pattern. The lattice parameter a and the crystallite size were calculated to demonstrate the crystalline structure of fluoridated and potassium containing HA. Extracted paired premolars were chosen to obtain a flat surface with opened tubules. It was observed that the tubules were covered by α 10μm layer of fluoridated and potassium containing HA under the SEM. As the experimental results show the nanoscale fluoridated and potassium containing hydroxyapatite occludes the dentin tubules.

  16. Fluoride release from three glass ionomer materials and the effects of varnishing with or without finishing.

    Science.gov (United States)

    McKnight-Hanes, C; Whitford, G M

    1992-01-01

    The release rates of fluoride from discs made from three glass ionomer products, Miracle Mix (MM), Ketac-Silver (KS) and Ketac-Bond (KB), into artificial saliva for 3 weeks were determined. The discs were either not varnished, varnished or varnished and finished. The release rates were not proportional to the fluoride concentrations of the products and were ordered: MM > KB > KS. The rates declined sharply as a function of time regardless of the product or treatment. Varnishing the discs caused a reduction of 61-76% depending on the product. Finishing the varnished discs produced a significant increase in the fluoride release from MM but had no effect on the release from KS or KB. In a separate study with MM, it was determined that the release rate of fluoride was inversely proportional to the powder: liquid ratio used to prepare the discs.

  17. The Effect of Fluoride in Osteoporosis.

    Science.gov (United States)

    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)

  18. Fluoride in African groundwater: Occurrence and mitigation

    NARCIS (Netherlands)

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

    2010-01-01

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

  19. Characterization of nanoscopic calcium fluoride films

    Science.gov (United States)

    Rehmer, A.; Kemnitz, E.

    2016-09-01

    Nano metal fluorides are appropriate materials for different applications e.g. heterogeneous catalysis, ceramic materials for laser applications and antireflective layers on glass, respectively. An easy way to synthesize such nano metal fluorides is the fluorolytic sol-gel synthesis which was developed some few years ago for HS-AlF3 [1] and MgF2.[2] CaF2 exhibits similar optical properties as MgF2, and thus, is a promising candidate for antireflective (AR) coatings. That means, CaF2 exhibits a lower refractive index (n500 = 1.44) as compared to common soda lime glass (n500 = 1.53). Hence, we present an easy synthesis approach toward nanoscaled CaF2 sols to fabricate finally AR-CaF2 films by dip coating. Irrespective of the choice of the calcium precursor, the CaF2 films are porous in comparison to thin dense CaF2 films which are generated by physical vapor deposition. The characterization of CaF2 films was performed by different analytical methods like HR-SEM, XPS, EDX, EP (ellipsometric porosimetry), DLS (dynamic light scattering) and CA (contact angle measurement). Beside the good optical and mechanical properties, we have investigated the surface properties of CaF2 films on glass and silicon wafer e.g. surface morphology with elemental composition, open porosity, zeta potentials at the surfaces as well as the free energy of interaction between water and the CaF2 film.

  20. Fluoride: its role in dentistry

    Directory of Open Access Journals (Sweden)

    Livia Maria Andaló Tenuta

    2010-01-01

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

  1. Microcratering in Polyvinylidene Fluoride

    Science.gov (United States)

    Shu, Anthony John

    Dust is defined as macroparticles as small as a few molecules up to several micrometers in diameter. In the context of space exploration, it was originally seen only as a technical obstacle to applications; dust can damage instrument surfaces, coat mating surfaces preventing proper seals, and impair or obstruct measurements. Because of the ubiquity of dust in the solar system and its role in the origin of planets and other bodies, the study of dust and related phenomena has evolved to a scientific subdiscipline which can provide us insight into the origins and evolution of our solar system. In order to facilitate this, a hypervelocity dust accelerator has been built at the University of Colorado at Boulder and is being used to probe impact phenomena, dust mitigation techniques, dust detection techniques, and more. One such dust detector is a Polyvinylidene Fluoride (PVDF) dust detector. The PVDF dust detector is very lightweight and consumes little power. Due to these properties, PVDF detectors can potentially be used on any spacecraft to gain information on the local dust environment. It is not fully understood how this PVDF dust detector signal is generated, so at present can only be used as a dust counter. In this thesis I discuss the importance of the study of dust phenomena, describe the accelerator experiment, and describe a study conducted to determine the underlying physical principles of PVDF dust detectors. This included measuring crater size scaling laws, measuring the detailed shape of craters, and applying this data to simulations of the signals being generated by PVDF detectors.

  2. High-fluoride groundwater.

    Science.gov (United States)

    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.

  3. Structural stability, acidity, and halide selectivity of the fluoride riboswitch recognition site

    KAUST Repository

    Chawla, Mohit

    2015-01-14

    Using static and dynamics DFT methods we show that the Mg2+/F-/phosphate/water cluster at the center of the fluoride riboswitch is stable by its own and, once assembled, does not rely on any additional factor from the overall RNA fold. Further, we predict that the pKa of the water molecule bridging two Mg cations is around 8.4. We also demonstrate that the halide selectivity of the fluoride riboswitch is determined by the stronger Mg-F bond, which is capable of keeping together the cluster. Replacing F- with Cl- results in a cluster that is unstable under dynamic conditions. Similar conclusions on the structure and energetics of the cluster in the binding pocket of fluoride-inhibited pyrophosphatase suggest that the peculiarity of fluoride is in its ability to establish much stronger metal-halide bonds.

  4. Fast, selective adsorption of Cu2+ from aqueous mixed metal ions solution using 1,4,7-triazacyclononane modified SBA-15 silica adsorbent (SBA-TACN)

    Science.gov (United States)

    Tapaswi, Pradip Kumar; Moorthy, Madhappan Santha; Park, Sung Soo; Ha, Chang-Sik

    2014-03-01

    A new SBA-15 supported 1,4,7-triazacyclononane modified mesoporous silica adsorbent (SBA-TACN) has been synthesized using post grafting route and has thoroughly been characterized by small angle X-ray scattering (SAXS), N2 adsorption-desorption measurements, Fourier-transform infrared (FT-IR), solid-state 29Si MAS and 13C CP MAS NMR spectroscopy, transmission electron (TEM) and scanning electron microscopy (SEM), elemental analysis (EA) and thermogravimetric analysis (TGA). The synthesized material shows excellent copper (II) ion adsorption selectivity at pH 5 in mixed metal ion solution containing Cu2+, Cr3+, Ni2+, Co2+ and Li+. The copper ion adsorption capacity of the SBA-TACN can reach a maximum value of 0.67 mmol/g. Possible adsorption mechanism of metal ions on SBA-TACN has been discussed. The adsorbent can be readily regenerated by HNO3-NH3 treatment.

  5. Use of tube radial distribution of ternary mixed carrier solvents for introduction of absorption reagent for metal ion separation and online detection into capillary.

    Science.gov (United States)

    Fujinaga, Satoshi; Jinno, Naoya; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko

    2011-10-01

    When ternary mixed solvents consisting of water-hydrophilic/hydrophobic organic solvents are fed into a micro-space under laminar flow conditions, the solvent molecules are radially distributed in the micro-space. The specific fluidic behavior of the solvents is called the "tube radial distribution phenomenon (TRDP)". A novel capillary chromatography method was developed based on the TRDP that creates the inner major and outer minor phases in a tube, where the outer phase acts as a pseudo-stationary phase. This is called "tube radial distribution chromatography (TRDC)". In this study, Chrome Azurol S as an absorption reagent was introduced into the TRDC system for metal ion separation and online detection. The fused-silica capillary tube (75 μm id and 110 cm length) and water-acetonitrile-ethyl acetate mixture (3:8:4 volume ratio) including 20 mM Chrome Azurol S as a carrier solution were used. Metal ions, i.e. Co(II), Cu(II), Ni(II), Al(III), and Fe(III), as models were injected into the present TRDC system. Characteristic individual absorption characteristics and elution times were obtained as the result of complex formation between the metal ions and Chrome Azurol S in the water-acetonitrile-ethyl acetate mixture solution. The elution times of the metal ions were examined based on their absorption behavior; Co(II), Ni(II), Al(III), Fe(III), and Cu(II) were eluted in this order over the elution times of 4.7-6.8 min. The elution orders were determined from the molar ratios of metal ion to Chrome Azurol S and Irving-Williams series for bivalent metal ions. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Effect of fluoride on salivary immunoglobulins and sialic acid

    Directory of Open Access Journals (Sweden)

    Kadriye Görkem Ulu Güzel

    Full Text Available Summary Objective: The aim of our study was to evaluate the effect of fluoride on salivary immunoglobulin and sialic acid levels in children with dental fluorosis and healthy teeth who live in places with high fluoride concentration in drinking water. Method: Fifty-one (51 healthy children between 6 and 12 years old with no caries were randomly selected from primary schools enrolled in the dental-care program operated by the Department of Pediatric Dentistry. The children were divided into two groups: group I comprised 26 children with dental fluorosis [Thylstrup-Fejerskov Dental Fluorosis Index (TFI = 4] who lived in Isparta (2.7-2.8 ppm, and group II consisted of 25 children without dental fluorosis who were born in low-fluoride areas and had lived in Isparta for only the previous two years. Stimulated and unstimulated saliva were collected and analyzed for fluoride, salivary immunoglobulins and sialic acid levels. Results: Sialic acid level was correlated negatively with age. Levels of secretory immunoglobulin A (sIgA and secretory immunoglobulin G (sIgG were higher in children with dental fluorosis compared with those in group II, although these differences were not significant. Conclusion: Increased sIgA and sIgG levels may arrest the progression of caries in subjects with dental fluorosis. Given the risks of dental fluorosis, further studies of the effects of different fluoride levels in drinking water on salivary composition of children with mixed dentition are needed to confirm the results of our study and to provide data for comparison.

  7. Photoinitiated Electron Collection in Mixed-Metal Supramolecular Complexes: Development of Photocatalysts for Hydrogen Production DE-FG02-05ER15751 Final Report of Progress August 2017

    Energy Technology Data Exchange (ETDEWEB)

    Tanko, James M. [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

    2017-10-06

    Mixed-metal supramolecular complexes containing one or two RuII light absorbing subunits coupled through polyazine bridging ligands to a RhIII reactive metal center were prepared for use as photocatalysts for the production of solar H2 fuel from H2O. The electrochemical, photophysical, and photochemical properties upon variation of the monodentate, labile ligands coordinated to the Rh reactive metal center were investigated.

  8. Amine-templated one-dimensional metal sulfates including a mixed-valent Fe compound with a half-kagome structure.

    Science.gov (United States)

    Behera, J N; Rao, C N R

    2006-11-20

    Organically templated metal sulfates are relatively new. Six amine-templated transition-metal sulfates with different types of chain structures, including a novel iron sulfate with a chain structure corresponding to one half of the kagome structure, were synthesized by hydro/solvothermal methods. Amongst the one-dimensional metal sulfates, [C10N2H10][Zn(SO4)Cl2] (1) is the simplest, being formed by corner-linked ZnO2Cl2 and SO4 tetrahedra. [C6N2H18][Mn(SO4)2(H2O)2] (2) and [C2N2H10][Ni(SO4)2(H2O)2] (3) have ladder structures comprising four-membered rings formed by SO4 tetrahedra and metal-oxygen octahedra, just as in the mineral kröhnkite. [C4N2H12][V(III)(OH)(SO4)2]H2O (4) and [C4N2H12][VF3(SO4)] (5) exhibit chain topologies of the minerals tancoite and butlerite, respectively. The structure of [C4N2H12][H3O][Fe(III)Fe(II) F6(SO4)] (6) is noteworthy in that it corresponds to half of the hexagonal kagome structure. It exhibits ferrimagnetic properties at low temperatures and the absence of frustration, unlike the mixed-valent iron sulfate with the full kagome structure.

  9. Synthesis, structure characterization and biological activity of selected metal complexes of sulfonamide Schiff base as a primary ligand and some mixed ligand complexes with glycine as a secondary ligand

    Science.gov (United States)

    Sharaby, Carmen M.; Amine, Mona F.; Hamed, Asmaa A.

    2017-04-01

    The current work reports synthesis of metal complexes and mixed ligand complexes of a novel sulfonamide Schiff base ligand (HL) resulted from the condensation of sulfametrole [N‧-(4-methoxy-1,2,5-thiadiazol-3-yl]sulfanilamide and acetyl-acetone as a primary ligand and glycine as a secondary ligand. The metal complexes and mixed ligand complexes of HL Schiff base ligand were synthesized and characterized using different physicochemical studies as elemental analyses, mass spectra, conductivity measurement, IR spectra, 1H NMR spectra, UV-vis Spectra, solid reflectance, magnetic susceptibility, thermal analyses (TGA and DTA) and their microbial and anticancer activities. The spectroscopic data of the complexes suggest their 1:2(L1:M) complex structures and 1:2:2(L1:L2:M) mixed ligand complex structures, where L1 = HL and L2 = glycine. Also, the spectroscopic studies suggested the octahedral structure for all complexes. The synthesized Schiff base, its metal and mixed ligand complexes were screened for their bacterial, antifungal and anticancer activity. The activity data show that the metal complexes and mixed ligand complexes exhibited promising microbial and anticancer activities than their parent HL Schiff base ligand, also the data show that the mixed ligand complexes more effective than the metal complexes.

  10. The role of fluoride in erosion therapy.

    Science.gov (United States)

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

    2014-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Nagpal D

    2007-03-01

    Full Text Available Many industrialized countries have reported a decline in caries prevalence over the past few decades. These reductions have been related to the regular use of fluoride dentifrices. Fluoride dentifrices are the most cost-effective and efficient means of caries prevention. However, there have been concerns regarding the risk of fluorosis in children due to the ingestion of dentifrices. This has led to the use of dentifrices with low concentration of fluoride. Salivary fluoride levels after tooth-brushing have been shown to be related to the anticaries efficacy of fluoride dentifrices. The present study was designed to evaluate the effect of the concentration of fluoride in the dentifrice, on the salivary fluoride level in children. Twenty children in the age group of five to six years were randomly selected and divided into two groups using, either 500ppm or 1000ppm fluoride dentifrice (sodium monofluorophosphate. Salivary fluoride levels at 0, 15, 30, 45, 60, minutes after brushing were estimated. The data collected was statistically evaluated using the unpaired t-test. The results showed that salivary fluoride levels following use of 500ppm fluoride dentifrice were significantly lower than 1000ppm fluoride dentifrice. The low salivary fluoride levels may thereby reduce the anticaries efficacy. Hence, the pros and cons of recommending a low fluoride concentration dentifrice must be judiciously considered.

  12. Impacts of antioxidants on hydroxyl radical production from individual and mixed transition metals in a surrogate lung fluid

    Science.gov (United States)

    Charrier, Jessica G.; Anastasio, Cort

    2011-12-01

    Inhalation of ambient particulate matter causes morbidity and mortality in humans. One hypothesized mechanism of toxicity is the particle-induced formation of reactive oxygen species (ROS) - including the highly damaging hydroxyl radical ( rad OH) - followed by inflammation and a variety of diseases. While past studies have found correlations between ROS formation and a variety of metals, there are no quantitative measurements of rad OH formation from transition metals at concentrations relevant to 24-hour ambient particulate exposure. This research reports specific and quantitative measurements of rad OH formation from 10 individual transition metals (and several mixtures) in a cell-free surrogate lung fluid (SLF) with four antioxidants: ascorbate, citrate, glutathione, and uric acid. We find that Fe and Cu can produce rad OH under all antioxidant conditions as long as ascorbate is present and that mixtures of the two metals synergistically increase rad OH production. Manganese and vanadium can also produce rad OH under some conditions, but given that their ambient levels are typically very low, these metals are not likely to chemically produce significant levels of rad OH in the lung fluid. Cobalt, chromium, nickel, zinc, lead, and cadmium do not produce rad OH under any of our experimental conditions. The antioxidant composition of our SLF significantly affects rad OH production from Fe and Cu: ascorbate is required for rad OH formation, citrate increases rad OH production from Fe, and both citrate and glutathione suppress rad OH production from Cu. MINTEQ ligand speciation modeling indicates that citrate and glutathione affect rad OH production by changing metal speciation, altering the reactivity of the metals. In the most realistic SLF (i.e., with all four antioxidants), Fe generates approximately six times more rad OH than does the equivalent amount of Cu. Since levels of soluble Fe in PM are typically higher than those of Cu, our results suggest that Fe

  13. Fluoride remediation using floating macrophytes

    Directory of Open Access Journals (Sweden)

    Naba Kumar Mondal

    2014-04-01

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

  14. Special Report: Fluoridation of Water.

    Science.gov (United States)

    Hileman, Bette

    1988-01-01

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

  15. Special Report: Fluoridation of Water.

    Science.gov (United States)

    Hileman, Bette

    1988-01-01

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

  16. Alimentary fluoride intake in preschool children

    Science.gov (United States)

    2011-01-01

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

  17. New LaPrCe Mixed RE Alloy (LPC) And Its Application in Non-ferrous Metals

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    New LaPrCe mixed RE alloy (LPC) is a new product that is produced from LPC rare earth chloride. Large stockpile of La, Ce and Pr is concerned by persons in RE industry at home and abroad. Popularization of the alloy is helpful to solve this problem. Today, LPC is applied in many fields. It could substitute for Ce-rich mixed rare earths as the negative pole materials for NiMH batteries. When applied in microalloying steel, LPC could significantly improve the physical and mechanical performances of the materi...

  18. Fissure seal or fluoride varnish?

    Science.gov (United States)

    Deery, Christopher

    2016-09-01

    Data sourcesCochrane Oral Health Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, the US National Institutes of Health Trials Register and the World Health Organization (WHO) Clinical Trials Registry PlatformStudy selectionRandomised controlled trials (RCTs) with at least 12 months follow-up, in which fissure sealants, or fissure sealants together with fluoride varnishes, were compared with fluoride varnishes alone for preventing caries in occlusal surfaces of permanent teeth of children and adolescents.Data extraction and synthesisTwo reviewers independently screened search results, extracted data and assessed risk of bias of included studies. Studies were grouped and analysed on the basis of sealant material type (resin-based sealant and glass ionomer-based sealant, glass ionomer and resin-modified glass ionomer) and different follow-up periods. Odds ratio were calculated for caries or no caries on occlusal surfaces of permanent molar teeth. Mean differences were calculated for continuous outcomes and data. Evidence quality was assessed using GRADE (Grades of Recommendation, Assessment, Development and Evaluation) methods.ResultsEight RCTs involving a total of 1747 children aged five to ten years of age were included. Three trials compared resin-based fissure sealant versus fluoride varnish. Results from two studies (358 children) after two years were combined. Sealants prevented more caries, pooled odds ratio (OR) = 0.69 (95%CI; 0.50 to 0.94). One trial with follow-up at four and nine years found that the caries-preventive benefit for sealants was maintained, with 26% of sealed teeth and 55.8% of varnished teeth having developed caries at nine years. Evidence for glass-ionomer sealants was of low quality. One split-mouth trial analysing 92 children at two-year follow-up found a significant difference in favour of resin-based fissure sealant together with fluoride varnish compared with fluoride varnish only (OR

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    Objective: To assess the urinary fluoride excretion in preschool children after drinking fluoridated milk with 0.185 mg F and 0.375 mg F and to study the impact of use of fluoride toothpaste. Basic research design: Double-blind cross-over study. Participants: Nine healthy children, 2.5-4.5 years...... of age. Intervention: In a randomized order, participants drank 1.5 dl milk once daily for 7 days with no fluoride added (control), 0.185 mg fluoride added and 0.375 mg fluoride added. The experiment was performed twice with (Part I) and without (Part II) parental tooth brushing with 1,000 ppm fluoride...... toothpaste. The fluoride content in the piped drinking water was 0.5 mg F/L. Main outcome measure: Urinary fluoride excretion. Results: The 24-hour urinary fl uoride excretion/kg body weight varied from 0.014 mg F for the placebo intervention and non-fluoride toothpaste to 0.027 mg F for the 0.375 mg...

  20. Global affordability of fluoride toothpaste

    Directory of Open Access Journals (Sweden)

    Holmgren Christopher J

    2008-06-01

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

  1. Synthesis, characterization and antimicrobial activities of mixed ligand transition metal complexes with isatin monohydrazone Schiff base ligands and heterocyclic nitrogen base

    Science.gov (United States)

    Devi, Jai; Batra, Nisha

    2015-01-01

    Mixed ligand complexes of Co(II), Ni(II), Cu(II) and Zn(II) with various uninegative tridentate ligands derived from isatin monohydrazone with 2-hydroxynapthaldehyde/substituted salicylaldehyde and heterocyclic nitrogen base 8-hydroxyquinoline have been synthesized and characterized by elemental analysis, conductometric studies, magnetic susceptibility and spectroscopic techniques (IR, UV-VIS, NMR, mass and ESR). On the basis of these characterizations, it was revealed that Schiff base ligands existed as monobasic tridentate ONO bonded to metal ion through oxygen of carbonyl group, azomethine nitrogen and deprotonated hydroxyl oxygen and heterocyclic nitrogen base 8-hydroxyquinoline existed as monobasic bidentate ON bonded through oxygen of hydroxyl group and nitrogen of quinoline ring with octahedral or distorted octahedral geometry around metal ion. All the compounds have been tested in vitro against various pathogenic Gram positive bacteria, Gram negative bacteria and fungi using different concentrations (25, 50, 100, 200 μg/mL) of ligands and their complexes. Comparative study of antimicrobial activity of ligands, and their mixed complexes indicated that complexes exhibit enhanced activity as compared to free ligands and copper(II) Cu(LIV)(Q)ṡH2O complex was found to be most potent antimicrobial agent.

  2. PROPER RAIL STRUCTURE FOR TRAVELLING OF 320 t HOT METAL MIXING CAR%320 t混铁车走行线合理轨道结构

    Institute of Scientific and Technical Information of China (English)

    熊学政

    2001-01-01

    In light of the problems existing in the travelling line of 320 thot metal mixing car the present paper analyzes and discusses the proper structure of rail and advances certain proposals for the proper structural composition of the rail for travelling of the 320 t hot metal mixing car.The content in the discussion of the present paper is expecially suitable for design of proper structure of extra heavy metallurgical load carrying rail.%针对320t混铁车起行线出现的问题,开展合理轨道结构的分析与探讨。根据轮轨关系及其原理,进行轨道动态参数测试、钢轨试验及分析,以及路基承载力试验后,提出320t混铁车走行线合理轨道结构组成和建议。探讨的内容为特大型冶金运载轨道合理结构。

  3. Pyrochemical recovery of plutonium from calcium fluoride reduction slag

    Science.gov (United States)

    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.

  4. Thermohaline instability and rotation-induced mixing. I - Low- and intermediate-mass solar metallicity stars up to the end of the AGB

    CERN Document Server

    Charbonnel, Corinne

    2010-01-01

    (abridged) Numerous spectroscopic observations provide compelling evidence for non-canonical processes that modify the surface abundances of low- and intermediate-mass stars beyond the predictions of standard stellar theory. We study the effects of thermohaline instability and rotation-induced mixing in the 1-4 Msun range at solar metallicity. We present evolutionary models by considering both thermohaline and rotation-induced mixing in stellar interior. We discuss the effects of these processes on the chemical properties of stars from the zero age main sequence up to the end of the second dredge-up on the early-AGB for intermediate-mass stars and up to the AGB tip for low-mass stars. Model predictions are compared to observational data for lithium,12C/13C,[N/C],[Na/Fe],16O/17O, and 16O/18O in Galactic open clusters and in field stars with well-defined evolutionary status,as well as in planetary nebulae. Thermohaline mixing simultaneously accounts for the observed behaviour of 12C/13C,[N/C], and lithium in lo...

  5. Local source identification of trace metals in urban/industrial mixed land-use areas with daily PM10 limit value exceedances

    Science.gov (United States)

    Fernández-Olmo, Ignacio; Andecochea, Carlos; Ruiz, Sara; Fernández-Ferreras, José Antonio; Irabien, Angel

    2016-05-01

    This study presents the analysis of the concentration levels, inter-site variation and source identification of trace metals at three urban/industrial mixed land-use sites of the Cantabria region (northern Spain), where local air quality plans were recently approved because the number of exceedances of the daily PM10 limit value according to the Directive 2008/50/EC had been relatively high in the last decade (more than 35 instances per year). PM10 samples were collected for over three years at the Torrelavega (TORR) and Los Corrales (CORR) sites and for over two years at the Camargo (GUAR) site and analysed for the presence of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), nickel (Ni), titanium (Ti), vanadium (V), molybdenum (Mo), manganese (Mn), iron (Fe), antimony (Sb) and zinc (Zn). Analysis of enrichment factors revealed an anthropogenic origin of most of the studied elements; Zn, Cd, Mo, Pb and Cu were the most enriched elements at the three sites, with Fe and V as the least enriched elements. Positive Matrix Factorisation (PMF) and pollutant roses (Cu at TORR, Zn at CORR and Mn at GUAR) were used to identify the local sources of the studied metals. Analysis of PMF results revealed the main sources of trace metals at each site as road traffic at the TORR site, iron foundry and casting industry at the CORR site and a ferro-manganese alloy industry at the GUAR site. Other sources were also identified at these sites, but with much lower contributions, such as minor industrial sources, combustion and traffic mixed with the previous sources.

  6. Synthesis, Characterization, and Physicochemical Studies of Mixed Ligand Complexes of Inner Transition Metals with Lansoprazole and Cytosine

    Directory of Open Access Journals (Sweden)

    Sarika Verma

    2013-01-01

    Full Text Available Few complexes of inner transition metals [Th(IV, Ce(IV, Nd(III, Gd(III] have been synthesized by reacting their metal salts with lansoprazole, 2-([3-methyl-4-(2,2,2-trifluoroethoxypyridin-2-yl]methylsulfinyl-1H-benzoimidazole and cytosine. All the complexes were synthesized in ethanolic medium. The yield percentage rangs from 80 to 90%. The complexes are coloured solids. The complexes were characterized through elemental analyses, conductance measurements, and spectroscopic methods (FT IR, FAB Mass, 1H NMR and UV. An IR spectrum indicates that the ligand behaves as bidentate ligands. The metal complexes have been screened for their antifungal activity towards Aspergillus niger fungi. The interaction of inner transition metals with lansoprazole, in presence of cytosine, has also been investigated potentiometrically at two different temperatures 26±1°C and 36±1°C and at 0.1 M (KNO3 ionic strength. The stability constants of ternary complexes indicate the stability order as Th(IV < Ce(IV < Gd(III < Nd(III. logK values obtained are positive and suggest greater stabilization of ternary complexes. The values of thermodynamic parameters (free energy (ΔG, enthalpy (ΔH, and entropy (ΔS are also calculated.

  7. Turbulent Mixing of Metal and Silicate during Planet Accretion – and interpretation of the Hf-W chronometer

    DEFF Research Database (Denmark)

    Dahl, Tais Wittchen; Stevenson, David

    2010-01-01

    In the current view of planet formation, the final assembly of the Earth involved giant collisions between protoplanets (N1000 kmradius), with theMoon formed as a result of one such impact.At this stage the colliding bodies had likely differentiated into a metallic core surrounded by a silicate m...

  8. Modified endophytes for improving phyto remediation and mixed contaminations of heavy metals (Ni) and organic contaminants (Toluene)

    Energy Technology Data Exchange (ETDEWEB)

    Weyens, N.; Barac, T.; Lelie, D. van der; Taghavi, S.; Vangronsveld, J.

    2009-07-01

    Phytoremediation is a promising technology for the remediation of soils and groundwater contaminated with heavy metals and organic pollutants. However, large-scale application of phytoremediation faces a number of obstacles including the levels of pollutants tolerated by the plant, the bioavailability of the contaminants and, in some cases, the evapotranspiration of volatile organic pollutants. (Author)

  9. Focus on fluorides: update on the use of fluoride for the prevention of dental caries.

    Science.gov (United States)

    Carey, Clifton M

    2014-06-01

    Improving the efficacy of fluoride therapies reduces dental caries and lowers fluoride exposure. 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. 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. 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. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Fluoride Varnishes--Is There a Correlation Between Fluoride Release and Deposition on Enamel?

    Science.gov (United States)

    Bolis, Carlo; Härtli, Gian Peider; Lendenmann, Urs

    2015-01-01

    Fluoride uptake of enamel after application of fluoride varnishes was compared with fluoride release into artificial saliva. The hypothesis was that fluoride uptake is higher for products exhibiting faster fluoride release. Fluoride varnishes, i.e. Fluor Protector S, Duraphat, MI Varnish, Clinpro White Varnish, Profluorid Varnish and Enamel Pro Varnish were applied on bovine enamel specimens. Subsequently, specimens were incubated in artificial saliva. After removal of the varnishes, surface bound fluoride was extracted with potassium hydroxide and measured with an ion-selective electrode. Structurally bound fluoride was etched from the same specimens with perchloric acid. Fluoride release of varnish films into artificial saliva was measured for comparison. After 4 h in artificial saliva, the highest total enamel fluoride uptake of 47.9 μg F·cm-² was found with Fluor Protector S, followed by Enamel Pro Varnish with 22.1 μg F·cm-². The other products ranged between 12-16 μg F·cm-². This was several times higher than the negative control. Fluoride uptake did not correlate with release into artificial saliva. During the first 4 h, Duraphat released the lowest and MI Varnish the highest amount of fluoride with 7.7 and 249 μg F·cm-², respectively. The fluoride uptake of these two products was not statistically different. Enamel fluoride uptake cannot be predicted from the fluoride release rate of a product. Hence, based on the results of this study, fluoride release into artificial saliva is no measure for the efficacy of a fluoride varnish.

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

    Science.gov (United States)

    Carey, Clifton M.

    2014-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Daniela Correia Cavalcante SOUZA

    2014-08-01

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

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Science.gov (United States)

    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.

  15. Aerosol synthesis and electrochemical analysis of niobium mixed-metal oxides for the ethanol oxidation reaction in acid and alkaline electrolyte

    Science.gov (United States)

    Konopka, Daniel A.

    Direct ethanol fuel cells are especially important among emerging electrochemical power systems with the potential to offset a great deal of the energy demand currently met through the use of fossil fuels. Ethanol can be refined from petroleum sources or attained from renewable biomass, and is more easily and safely stored and transported than hydrogen, methanol or gasoline. The full energy potential of ethanol in fuel cells can only be realized if the reaction follows a total oxidation pathway to produce CO2. This must be achieved by the development of advanced catalysts that are electrically conductive, stable in corrosive environments, contain a high surface area on which the reaction can occur, and exhibit a bi-functional effect for the ethanol oxidation reaction (EOR). The latter criterion is achievable in mixed-metal systems. Platinum is an effective metal for catalyzing surface reactions of many adsorbates and is usually implemented in the form of Pt nanoparticles supported on inexpensive carbon. This carbon is believed to be neutral in the catalysis of Pt. Instead, carbon can be replaced with carefully designed metals and metal oxides as co-catalysis or support structures that favorably alter the electronic structure of Pt slightly through a strong metal support interaction, while also acting as an oxygen source near adsorbates to facilitate the total oxidation pathway. Niobium mixed-metal-oxides were explored in this study as bi-functional catalyst supports to Pt nanoparticles. We developed a thermal aerosol synthesis process by which mesoporous powders of mixed-metal-oxides decorated with Pt nanoparticles could be obtained from liquid precursors within ˜5 seconds or less, followed by carefully refined chemical and thermal post-treatments. Exceptionally high surface areas of 170--180m2/g were achieved via a surfactant-templated 3D wormhole-type porosity, comparable on a per volume basis to commercial carbon blacks and high surface area silica supports

  16. Study of Ni Metallization in Macroporous Si Using Wet Chemistry for Radio Frequency Cross-Talk Isolation in Mixed Signal Integrated Circuits

    Directory of Open Access Journals (Sweden)

    King-Ning Tu

    2011-05-01

    Full Text Available A highly conductive moat or Faraday cage of through-the-wafer thickness in Si substrate was proposed to be effective in shielding electromagnetic interference thereby reducing radio frequency (RF cross-talk in high performance mixed signal integrated circuits. Such a structure was realized by metallization of selected ultra-high-aspect-ratio macroporous regions that were electrochemically etched in p− Si substrates. The metallization process was conducted by means of wet chemistry in an alkaline aqueous solution containing Ni2+ without reducing agent. It is found that at elevated temperature during immersion, Ni2+ was rapidly reduced and deposited into macroporous Si and a conformal metallization of the macropore sidewalls was obtained in a way that the entire porous Si framework was converted to Ni. A conductive moat was as a result incorporated into p− Si substrate. The experimentally measured reduction of crosstalk in this structure is 5~18 dB at frequencies up to 35 GHz.

  17. 76 FR 37129 - Determination That SODIUM FLUORIDE F 18 (Sodium Fluoride F-18) Injection, 10 to 200 Millicuries...

    Science.gov (United States)

    2011-06-24

    ... HUMAN SERVICES Food and Drug Administration Determination That SODIUM FLUORIDE F 18 (Sodium Fluoride F... Drug Administration (FDA) has determined that SODIUM FLUORIDE F 18 (sodium fluoride F-18) injection, 10... FLUORIDE F 18 injection, 10 to 200 mCi/mL, if all other legal and regulatory requirements are met. FOR...

  18. Conversion of ethanol to 1,3-butadiene over Na doped ZnxZryOz mixed metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Baylon, Rebecca A.; Sun, Junming; Wang, Yong

    2016-01-01

    Despite numerous studies on different oxide catalysts for the ethanol to 1,3-butadiene reaction, few have identified active sites (i.e., type of acidity) correlated to the catalytic performances. In this work, the type of acidity needed for ethanol to 1,3-butadiene conversion has been studied over Zn/Zr mixed oxide catalysts. Specifically, synthesis method, Zn/Zr ratio, and Na doping have been used to control the surface acid-base properties, as confirmed by characterizations such as NH3-TPD and IR-Py techniques. The 2000 ppm Na doped Zn1Zr10Oz-H with balanced base and weak Bronsted acid sites was found to give not only high selectivity to 1,3-butadiene (47%) at near complete ethanol conversion (97%), but also exhibited a much higher 1,3-butadiene productivity than other mixed oxides studied.

  19. Behaviour of fluoride and dissolved silicon in Gouthami Godavari estuarine environment

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, V.V.; Sudhakar, U.; Varaprasad, S.J.D.

    post-monsoon season. However, during premonsoon season, removal of approximately 16% in case of fluoride and 41% in case of dissolved silicon was found during mixing of sea and river waters. The possible mechanisms for removal of both the elements have...

  20. Salivary fluoride levels after use of high-fluoride dentifrice.

    Science.gov (United States)

    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 dentifrices (P dentifrice enhanced the bioavailability of salivary F, being an option for caries management in patients with high caries risk.

  1. Mixing processes during the evolution of red giants with moderate metal deficiencies the role of molecular-weight barriers

    CERN Document Server

    Charbonnel, C; Wallerstein, G; Charbonnel, Corinne; Brown, Jeffery A.; Wallerstein, George

    1997-01-01

    We have assembled accurate abundance data for Li, C, and N as well as the 12C/13C ratio for five field giants with [Fe/H]=-0.6 including Arcturus and two stars in the globular cluster 47 Tuc. Using their very precise Mbol values obtained from HIPPARCOSparallaxes, we can place them into an evolutionary sequence. The sequence shows that the 12C/13C ratios ratios drops from 20 to near 7 between Mbol=+1 and +0.5, while Li disappears. At the same time the 12C/14N ratio diminishes by 0.2 to 0.4 dex. The two stars in 47 Tuc with Mbol near -2.0 show even lower 12C14N ratios by 0.4 dex indicating further mixing as they evolved to the top of the red giant branch. These observations confirm the existence of an extra-mixing process that becomes efficient on the red giant branch only when the low-mass stars reach the so-called luminosity function bump. We use the values of the carbon isotopic ratio observed in our sample to get constraints on the mu-barriers that may shield the central regions of a star from extra-mixing....

  2. Renal fluoride excretion in children following topical application of fluoride varnish.

    Science.gov (United States)

    García-Hoyos, F; Barbería, E; García-Camba, P; Varela, M

    2012-12-01

    To demonstrate that the application of dental fluoride varnishes in children increases urinary fluoride excretion. From a randomly assembled group of 42 children aged between 5 and 8 years, residing in a community with non-fluoridated water, spot urinary samples were taken before the topical application of dental fluoride varnish and 2 hours afterwards. In an age-matched control group of 16 children from the same community, who received no treatment, samples were taken the same way. The urinary excretion of fluoride was analysed by determining fluoride ion (F-) level and fluoride/creatinine (F/Cr) ratio in the urine. In the study group, the average pre- and post-treatment F/Cr ratios were 0.42 and 1.38 mg/g, respectively (p fluoride varnish leads to a significant increase in urine F-, which is attributable to the application of the product.

  3. Fluoride intake from fluids and urinary fluoride excretion by young children in Kuwait: a non-fluoridated community.

    Science.gov (United States)

    Akpata, Enosakhare S; Behbehani, Jawad; Akbar, Jaber; Thalib, Lukman; Mojiminiyi, Olusegun

    2014-06-01

    To determine the pattern of fluid consumption, fluoride intake from the fluids and urinary fluoride excretion by children aged 1-9 years in Kuwait, a nonfluoridated community. Using the cluster sampling technique, children aged 1-9 years were chosen from 2000 randomly selected households in Kuwait. Questionnaires were then administered to their mothers to determine the children's daily fluid intake. Fluoride concentrations in tap water as well as all brands of bottled water and beverages consumed by the children were measured, using the fluoride ion-specific electrode. Fluoride excretion was determined in 400 randomly selected children, based on fluoride/creatinine ratio. The mean daily fluid consumption by the children was high, being 1115-1545 ml. About 40% of the fluid intake was plain (tap and bottled) water and approximately 10% of the children drank bottled water exclusively. Fluoride concentration in tap water was low (0.04±SD 0.02 ppm), but was higher in bottled water (0.28±SD 0.40 ppm). Mean daily fluoride ingestion from fluids was 0.013-0.018 mg/kg body weight (bw). Even after allowing for fluoride ingestion from other sources, mean daily fluoride ingestion was still below 0.1 mg/kg bw set by the United States of America Institute of Medicine as the lowest-observed-adverse-effect level for moderate enamel fluorosis in children aged up to 8 years. Furthermore, the mean daily urinary fluoride excretion of 128-220 μg was below the provisional standard of 360-480 μg for optimal fluoride usage by children aged 3-5 years. Fluoride ingestion from fluids and urinary fluoride excretion by the children were below the recommendations for optimal fluoride usage. Thus, there is room for an upward adjustment of fluoride level in public drinking water supplies in Kuwait, as a caries preventive measure. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Removal and accumulation of cadmium and lead by Typha latifolia exposed to single and mixed metal solutions.

    Science.gov (United States)

    Alonso-Castro, Angel Josabad; Carranza-Alvarez, Candy; Alfaro-De la Torre, Ma Catalina; Chávez-Guerrero, Leonardo; García-De la Cruz, Ramón Fernando

    2009-11-01

    We investigated the effect of Cd and Pb on the growth of the aquatic macrophyte Typha latifolia; the removal from the solution and the accumulation of these elements by the plant were also studied. Thus, small plants of T. latifolia, collected from a noncontaminated site, were exposed for 10 days to Cd and Pb, in a single solution or in mixture solutions, at two concentrations of the metals (5 and 7.5 mg/L). Our results showed that T. latifolia removed effectively Cd and Pb from solutions and was able to accumulate these metals in the roots and, to a lesser extent, in the leaves. Our findings suggested a synergistic effect of Cd and Pb with respect to the toxicity to T. latifolia. Additionally, Cd diminished the Pb absorption by T. latifolia. Our results confirmed, using scanning electron microscopy, the internalization of Cd and Pb in T. latifolia.

  5. Determination of Fluoride in Various Samples and Some Infusions Using a Fluoride Selective Electrode

    OpenAIRE

    TOKALIOĞLU, Şerife; Kartal, Şenol; ŞAHİN, Uğur

    2004-01-01

    The determination of fluoride in some environmental samples was performed using a fluoride ion-selective electrode. Fluoride concentrations were determined in drinking waters (from different provinces, districts and villages in Turkey), fruit juices, bottled water samples, toothpastes and tooth powders, liquors of Turkish coffee, coffee, linden, rose hip, and various brand tea infusions, and dust samples collected from the Erciyes University campus car park. The average fluoride conc...

  6. Estuarine response of fluoride - Investigations in Azhikode Estuary

    Digital Repository Service at National Institute of Oceanography (India)

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

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

  7. Groundwater fluoride enrichment in an active rift setting: Central Kenya Rift case study

    Energy Technology Data Exchange (ETDEWEB)

    Olaka, Lydia A., E-mail: lydiaolaka@gmail.com [Department of Geology, University of Nairobi, P.O Box 30197, Nairobi (Kenya); Wilke, Franziska D.H. [Geoforschungs Zentrum, Telegrafenberg, 14473 Potsdam (Germany); Olago, Daniel O.; Odada, Eric O. [Department of Geology, University of Nairobi, P.O Box 30197, Nairobi (Kenya); Mulch, Andreas [Senckenberg Biodiversity and Climate Research Centre, Senckenberganlage 25, 60325 Frankfurt (Germany); Institut für Geowissenschaften, Goethe Universität Frankfurt, Altenhöferallee 1, 60438 Frankfurt (Germany); Musolff, Andreas [UFZ-Helmholtz-Centre for Environmental Research, Department of Hydrogeology, Permoserstr. 15, 04318 Leipzig (Germany)

    2016-03-01

    in Naivasha as well as similar active rift setting environments. - Highlights: • Rocks and water samples from the Central Kenya Rift, were analyzed for F{sup −}. • 73% of water sources are above the NEMA health guideline (1.5 mg/L) on fluoride. • Fluoride concentration is highly variable in waters in the rift (0.22–74.98 mg/L). • Minerals (cordierite, muscovite, villiaumite) have high fluoride 308–6366 ppm. • Fluoride enriches in water by rock alteration, evaporation and geothermal mixing.

  8. Fluoride Importance in Controlling Caries and Fluorosis

    OpenAIRE

    Gaurav Solanki

    2012-01-01

    The use of fluorides for oral health has always involved a balance between the protective benefit against dental caries and the risk of developing fluorosis. The link between fluoride and dental health was established to determining the causes of dental fluorosis or enamel mottling. Fluorosis in Indian children was highly prevalent in the early 1990s. Policy were introduced to control fluoride exposure and to reduce the prevalence of fluorosis. The study aimed of describing the prevalence, se...

  9. Fluoride Importance in Controlling Caries and Fluorosis

    OpenAIRE

    Gaurav Solanki

    2012-01-01

    The use of fluorides for oral health has always involved a balance between the protective benefit against dental caries and the risk of developing fluorosis. The link between fluoride and dental health was established to determining the causes of dental fluorosis or enamel mottling. Fluorosis in Indian children was highly prevalent in the early 1990s. Policy were introduced to control fluoride exposure and to reduce the prevalence of fluorosis. The study aimed of describing the prevalence, se...

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

    NARCIS (Netherlands)

    Vieira, A; Ruben, JL; Huysmans, MCDNJM

    2005-01-01

    This study aimed at evaluating the effect of 1 and 4% titanium tetrafluoride (TiF4) gels, amine fluoride (AmF) 1 and 0.25% and a fluoride varnish (FP) on the prevention of dental erosion. Two experimental groups served as controls, one with no pretreatment and another one pre-treated with a fluoride

  11. The first barium tin(II) bromide fluoride

    Science.gov (United States)

    Dénès, Georges; Merazig, Hocine; Muntasar, Abdualhafeed; Porterfield, Robyn

    2014-04-01

    In an effort to prepare barium tin(II) bromide fluorides for the first time, possibly similar to the chloride fluorides obtained earlier in our laboratory, precipitation reactions were carried out by mixing aqueous solutions of SnF2 and of BaBr2.2H2O. In contrast with the chloride fluoride system, a single powdered phase was obtained throughout the SnF2 - BaBr2 system, with the yield being maximum at X ≈ 0.25, where X is the molar fraction of barium bromide in the reaction mixture. Phase identification with the JCPDS database failed to produce a match, confirming that a new phase had been produced. The exact chemical composition of the new compound has not been obtained yet. Based on the X value for the maximum yield, the Sn/Ba ratio is likely to be 3/1 or 2/1. The Mössbauer spectrum at ambient conditions shows that bonding to tin(II) is covalent, therefore with the tin lone pair being stereoactive. The Mössbauer parameters ( δ = 3.68 mm/s, Δ = 0.99 mm/s) are similar to those of SnBrF and of Sn2BrF5, thereby showing that tin is bonded to both fluorine and bromine. The larger isomer shift and lower quadrupole splitting than in tin(II) fluorides show that the stereoactivity of the tin lone pair is lower than in the fluorides. The Mössbauer parameters fit well the linear correlation of the quadrupole splitting versus the isomer shift" that has been shown to be present in other series of tin(II) compounds. The linear decrease on this correlation shows that the contribution of non-spherical orbitals ( p and d) to the lone pair is a much larger contributor to the quadrupole splitting than lattice distortions. The structure is likely made of Ba2+ cations and tin(II) fluoride bromide polyatomic anions, with covalent bonding withinthe anions.

  12. Mathematical Modelling of the Process of Tungsten Fluorides Reduction by Hydrogen

    Directory of Open Access Journals (Sweden)

    Brendakov Roman

    2016-01-01

    Full Text Available The process of tungsten fluorides reduction by hydrogen is a component part of Fluoride technology of tungsten conversion. Nowadays the researchers are definitely interested in studying this process. It is connected with common use of metal tungsten products in different sectors of the economy, which is the result of unique qualities of this metal. With the help of physical and mathematical modelling of the process of tungsten hexafluoride reduction by hydrogen, it becomes possible to create an import substitution technology of metal tungsten conversion. Fluoride technology of tungsten conversion allows putting different coverings and make tungsten products of different shapes, which is impossible to get traditionally. The process of tungsten fluorides reduction by hydrogen can be referred to CVD processes (Chemical Vapor Deposition. Common use of CVD technologies for getting metal products and coverings is limited by definite problems, connected with access difficulties to initial components of research and the lack of information about their basic thermal characteristics. Therefore, mathematical description of the initial components mass-moving process, which provides with optimal value of their concentration in gas flow and in precipitation zone, is a question of current importance.

  13. Effect of low-concentration daily topical fluoride application on fluoride release of giomer and compomer: An in vitro study

    Directory of Open Access Journals (Sweden)

    K S Dhull

    2011-01-01

    Full Text Available Aims and Objective: To determine the effect of low-concentration daily topical fluoride application on fluoride release of Giomer and Compomer and to compare the amount of fluoride release from Giomer to that of Compomer. Materials and Methods: Forty-eight specimens of each Giomer and Compomer were divided into four treatment groups, namely, control group, fluoridated dentifrice (500 ppm once-daily group, fluoridated dentifrice (500 ppm twice-daily group and fluoridated dentifrice (500 ppm once-daily + fluoridated mouthwash (225 ppm group. Each specimen was suspended in demineralising solution for 6 h and remineralising solution for 18 h. Fluoride release was measured in both the demineralising solution and the remineralising solution daily for 21 days. Total daily fluoride release for each specimen was calculated by adding the amount released in the demineralising solution to that released in the remineralising solution. Results and Conclusion: The fluoride release (ppm was found to be higher in Giomer when compared with Compomer. The fluoride released from Giomer and Compomer was significantly higher in the acidic demineralising solution than in the neutral remineralising solution. It was found that increasing fluoride exposure significantly increased fluoride release from Giomer and Compomer. It was found that the fluoride release from the subgroups of Giomer and Compomer was in the following order: fluoridated dentifrice twice-daily > fluoridated dentifrice once-daily + fluoridated mouthwash > fluoridated dentifrice once-daily > control group. It was found that Giomer showed a greater fluoride uptake Compomer.

  14. Gramicidin D enhances the antibacterial activity of fluoride

    OpenAIRE

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

    2014-01-01

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

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

    OpenAIRE

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

    2014-01-01

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

  16. Synthesis and characterization of mixed ligand complexes of bio-metals with pyrimidine nucleoside (uridine) and amino acids

    Indian Academy of Sciences (India)

    P Rabindra Reddy; A Mohan Reddy

    2000-12-01

    The mixed ligand complexes of Cu(II), Ni(II) and Co(II) with uridine and amino acids, L-alanine, L-phenylalanine and L-tryptophan were synthesized and characterized by elemental analysis, conductivity data, infrared spectra, electronic spectra and magnetic susceptibility data. In these complexes, the nucleoside (uridine) acts as a monodentate ligand coordinating through O(4) under the conditions of investigation, whereas the amino acids coordinate through the carboxylate oxygen and the amino nitrogen. Distorted octahedral geometry for Cu(II) and octahedral geometries for both Ni(II) and Co(II) are proposed.

  17. Fluoride assay methodology for carbonated beverages.

    Science.gov (United States)

    Heilman, Judith R; Levy, Steven M; Wefel, James S; Patterson, Kristine Y; Cutrufelli, Rena; Pehrsson, Pamela R; Holden, Joanne M

    2006-01-01

    The purpose of this paper was to review different methodological techniques used for the assessment of fluoride in carbonated beverages, and compare results using a fluoride ion electrode direct read method with and without a prior decarbonation treatment. The carbonated beverages in this study were either purchased locally at grocery stores in Iowa City, Iowa, or purchased as part of a national representative sampling approach included in the National Fluoride Database and Intake Assessment Study (NFDIAS). The samples were compared with and without a decarbonating process. Soda pop and beer samples were analyzed by removing a 1-ml sample and adding a 1-ml buffer solution. The fluoride concentration of the sample and buffer combination was then determined using a fluoride ion specific electrode. There was no significant difference in the fluoride concentration of the samples with or without prior decarbonation. The mean absolute difference between the soda pop group with and without decarbonation was 0.01 ppm F, while results from the beer samples showed variation of 0.00 to 0.02 parts per million fluoride (ppm F). These differences were not statistically significant for the soda pop or beer groups (P=.50 and P=.74, respectively). Whether or not decarbonation was conducted prior to analysis, the fluoride assay results were the same. Therefore, decarbonation of soda pop and beer was deemed unnecessary prior to fluoride analysis.

  18. High fluoride exposure in hemodialysis patients.

    Science.gov (United States)

    Bello, V A; Gitelman, H J

    1990-04-01

    The observation of higher plasma flouride levels in our hemodialysis (HD) patients than our continuous ambulatory peritoneal dialysis (CAPD) patients (4.0 +/- 0.5 mumol/L [n = 17] v 2.5 +/- 0.3 mumol/L [n = 17], P less than 0.005) prompted an evaluation of fluoride metabolism during HD. We found that serum fluoride was completely ultrafiltrable across cuprophane membranes (99% +/- 4%) and that HD produced acute changes in plasma fluoride levels that correlated well with the fluoride gradient between plasma and dialysis fluid at the start of dialysis. Our HD fluids contained significantly higher fluoride concentrations than were present in commercially prepared peritoneal dialysis fluid. Our fluids are prepared from fluoridated tap water that is purified by reverse osmosis (RO). We conclude that the different concentrations of fluoride in our dialysis fluids account for the differences in the plasma flouride concentrations between our dialysis groups. Since many HD units rely on RO systems to purify fluoridated tap water, it is likely that many HD patients are being exposed inadvertently to increased concentrations of fluoride.

  19. Application of fluoride iontophoresis to improve remineralization.

    Science.gov (United States)

    Kim, H E; Kwon, H K; Kim, B I

    2009-10-01

    Iontophoresis is generally used to maximize the therapeutic action of drugs in medicine. This technique can be used to improve the remineralization effect of topical fluoride applications in dentistry. The aim of this study was to compare the remineralization effect of fluoride iontophoresis (FI) with the conventional fluoride application (CFA) method in vitro. Sixty bovine enamel specimens were divided into three groups: no fluoride treatment, CFA and FI. Fluoride was applied to the demineralized specimens for 4 min in each experimental group. The types of fluoride system used for application were 1.23% acidulated phosphate fluoride gel (12 300 p.p.m. F, pH 3.5) and 2% sodium fluoride solution (9050 p.p.m. F, pH 7) in the experimental groups. All the specimens were then placed in a remineralizing solution for 24 h. This cycle was repeated five times. An iontophoresis device (0.4 mA, 12 V) was used in the FI groups. The efficacy of this technique was evaluated by measuring changes in the surface microhardness and lesion depth of the specimens using confocal laser scanning microscope (CLSM). Data were analysed using anova and Tukey's post hoc test (P fluoride application methods (P > 0.05). When the lesion depth was measured using CLSM imaging, there was also no significant difference between the FI and CFA groups (P > 0.05). In conclusion, FI was not significantly superior to CFA in terms of the remineralization effect.

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

    Science.gov (United States)

    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.

  1. Four-wave mixing signal enhancement and optical bistability of a hybrid metal nanoparticle-quantum dot molecule in a nanomechanical resonator.

    Science.gov (United States)

    Li, Jian-Bo; Liang, Shan; Xiao, Si; He, Meng-Dong; Kim, Nam-Chol; Chen, Li-Qun; Wu, Gui-Hong; Peng, Yu-Xiang; Luo, Xiao-Yu; Guo, Ze-Ping

    2016-02-08

    We investigate theoretically four-wave mixing (FWM) response and optical bistability (OB) in a hybrid nanosystem composed of a metal nanoparticle (MNP) and a semiconductor quantum dot (SQD) coupled to a nanomechanical resonator (NR). It is shown that the FWM signal is enhanced by more than three orders of magnitude as compared to that of the system without exciton-phonon interaction, and the FWM signal can also be suppressed significantly and broadened due to the exciton-plasmon interaction. As the MNP couples strongly with the SQD, the bistable FWM response can be achieved by adjusting the SQD-MNP distance and the pumping intensity. For a given pumping constant and a fixed SQD-MNP distance, the enhanced exciton-phonon interaction can promote the occurrence of bistability. Our findings not only present a feasible way to detect the spacing between two nanoparticles, but also hold promise for developing quantum switches and nanoscale rulers.

  2. Ferromagnetic exchange anisotropy from antiferromagnetic superexchange in the mixed 3d-5d transition-metal compound Sr3CuIrO6.

    Science.gov (United States)

    Yin, Wei-Guo; Liu, X; Tsvelik, A M; Dean, M P M; Upton, M H; Kim, Jungho; Casa, D; Said, A; Gog, T; Qi, T F; Cao, G; Hill, J P

    2013-08-02

    We report a combined experimental and theoretical study of the unusual ferromagnetism in the one-dimensional copper-iridium oxide Sr(3)CuIrO(6). Utilizing Ir L(3) edge resonant inelastic x-ray scattering, we reveal a large gap magnetic excitation spectrum. We find that it is caused by an unusual exchange anisotropy generating mechanism, namely, strong ferromagnetic anisotropy arising from antiferromagnetic superexchange, driven by the alternating strong and weak spin-orbit coupling on the 5d Ir and 3d Cu magnetic ions, respectively. From symmetry consideration, this novel mechanism is generally present in systems with edge-sharing Cu(2+)O(4) plaquettes and Ir(4+)O(6) octahedra. Our results point to unusual magnetic behavior to be expected in mixed 3d-5d transition-metal compounds via exchange pathways that are absent in pure 3d or 5d compounds.

  3. Nonlinear lattice relaxation of photogenerated charge-transfer excitation in halogen-bridged mixed-valence metal complexes. II. Polaron channel

    Science.gov (United States)

    Mishima, A.; Nasu, K.

    1989-03-01

    The one-dimensional extended Peierls-Hubbard model with half-filled-band electrons is studied in order to clarify the lattice relaxation path of the photogenerated charge-transfer excitation in halogen-bridged mixed-valence metal complexes. The ground and excited states are calculated within mean-field theory for electrons and the adiabatic approximation for phonons. It is concluded that the main origin of the photoinduced absorption is a distant pair of the hole-polaron and the electron-polaron. This distant pair is created not from the ground state of the self-trapped exciton (STE), but from the excited states of the STE through their autodissociation. This is consistent with the experiment on the excitation energy dependence of the photoinduced absorption yield.

  4. Effect of hydrogen fluoride on two pigments in coleus

    Energy Technology Data Exchange (ETDEWEB)

    Lamprecht, W.O. Jr.; Powell, R.D.

    Coleus blumei Benth. Cv. 12th Man was fumigated with hydrogen fluoride gas. The treatment caused the development of lesions which originally involved the mesophyll but spread to and eventually included the epidermis. An anthocyanin, cyanidin-3,5-diglucoside acylated with p-coumaric acid, was destroyed and it was postulated that the flavanonol, dihydrokaempferol, was converted to the flavone, apigenin. The anthocyanin destruction and pigment conversion occurred following membrane injury and mixing of the cellular constituents. 17 references, 1 figure, 1 table.

  5. Effects of different kinds of fluorides on enolase and ATPase activity of a fluoride-sensitive and fluoride-resistant Streptococcus mutans strain

    NARCIS (Netherlands)

    van Loveren, C.; Hoogenkamp, M.A.; Deng, D.M.; ten Cate, J.M.

    2008-01-01

    Enolase and ATPase are sensitive to fluoride. It is unclear whether this sensitivity differs for F-sensitive and F-resistant cells or for different types of fluoride. Permeabilized cells of the fluoride-sensitive strain Streptococcus mutans C180-2 and its fluoride-resistant mutant strain C180-2 FR w

  6. Effects of different kinds of fluorides on enolase and ATPase activity of a fluoride-sensitive and fluoride-resistant Streptococcus mutans strain

    NARCIS (Netherlands)

    van Loveren, C.; Hoogenkamp, M.A.; Deng, D.M.; ten Cate, J.M.

    2008-01-01

    Enolase and ATPase are sensitive to fluoride. It is unclear whether this sensitivity differs for F-sensitive and F-resistant cells or for different types of fluoride. Permeabilized cells of the fluoride-sensitive strain Streptococcus mutans C180-2 and its fluoride-resistant mutant strain C180-2 FR

  7. Optical micro-spectroscopy of single metallic nanoparticles: quantitative extinction and transient resonant four-wave mixing.

    Science.gov (United States)

    Payne, Lukas; Zoriniants, George; Masia, Francesco; Arkill, Kenton P; Verkade, Paul; Rowles, Darren; Langbein, Wolfgang; Borri, Paola

    2015-01-01

    We report a wide-field imaging method to rapidly and quantitatively measure the optical extinction cross-section σ(ext) (also polarisation resolved) of a large number of individual gold nanoparticles, for statistically-relevant single particle analysis. We demonstrate a sensitivity of 5 nm(2) in σ(ext), enabling detection of single 5 nm gold nanoparticles with total acquisition times in the 1 min range. Moreover, we have developed an analytical model of the polarisation resolved σ(ext), which enabled us to extract geometrical particle aspect ratios from the measured σ(ext). Using this method, we have characterized a large number of nominally-spherical gold nanoparticles in the 10-100 nm size range. Furthermore, the method provided measurements of in-house fabricated nanoparticle conjugates, allowing distinction of individual dimers from single particles and larger aggregates. The same particle conjugates were investigated correlatively by phase-resolved transient resonant four-wave mixing micro-spectroscopy. A direct comparison of the phase-resolved response between single gold nanoparticles and dimers highlighted the promise of the four-wave mixing technique for sensing applications with dimers as plasmon rulers.

  8. Role of energetic mixed-oxide-fuel-sodium thermal interactions in liquid metal fast breeder reactor safety

    Energy Technology Data Exchange (ETDEWEB)

    Fauske, H.K.

    1976-01-01

    Based upon analysis, numerous experiments and examination of all known occurrences of large-mass vapor explosions, the following general behavior principle has emerged: Mixing of large quantities of a hot and cold liquid, a necessary condition for developing sustained pressures and large damage potential from thermal interaction, requires spontaneous nucleation upon contact. Since the contact temperature for the mixed-oxide-fuel-sodium system is well below the spontaneous-nucleation temperature for liquid sodium, the current interesting controversy regarding spontaneous nucleation and its role in the vapor-explosion mechanism itself is largely irrelevant for this system. Therefore, current practice is to use the pressure-volume curve determined by the expanding fuel vapor following a postulated hydrodynamic disassembly (which generally results from considering a number of unrealistic physical processes to occur) for safety evaluation. It follows that for reactors like FFTF and CRBR, the extremely unlikely event of a core meltdown is predicted to occur safely, with essentially no energetics involved.

  9. The influence of metal speciation in combustion waste on the efficiency of Cu, Pb, Zn, Cd, Ni and Cr bioleaching in a mixed culture of sulfur-oxidizing and biosurfactant-producing bacteria.

    Science.gov (United States)

    Karwowska, Ewa; Wojtkowska, Małgorzata; Andrzejewska, Dorota

    2015-12-15

    Metal leachability from ash and combustion slag is related to the physico-chemical properties, including their speciation in the waste. Metals speciation is an important factor that influences the efficiency of metal bioleaching from combustion wastes in a mixed culture of acidophilic and biosurfactant-producing bacteria. It was observed that individual metals tended to occur in different fractions, which reflects their susceptibility to bioleaching. Cr and Ni were readily removed from wastes when present with a high fraction bound to carbonates. Cd and Pb where not effectively bioleached when present in high amounts in a fraction bound to organic matter. The best bioleaching results were obtained for power plant slag, which had a high metal content in the exchangeable, bound to carbonates and bound to Fe and Mg oxides fractions- the metal recovery percentage for Zn, Cu and Ni from this waste exceeded 90%.

  10. Using a Consensus Conference to Characterize Regulatory Concerns Regarding Bioremediation of Radionuclides and Heavy Metals in Mixed Waste at DOE Sites

    Energy Technology Data Exchange (ETDEWEB)

    Denise Lach; Stephanie Sanford

    2006-09-01

    A consensus workshop was developed and convened with ten state regulators to characterize concerns regarding emerging bioremediation technology to be used to clean-up radionuclides and heavy metals in mixed wastes at US DOE sites. Two questions were explored: integrated questions: (1) What impact does participation in a consensus workshop have on the knowledge, attitudes, and practices of state regulators regarding bioremediation technology? (2) How effective is a consensus workshop as a strategy for eliciting and articulating regulators’ concerns regarding the use of bioremediation to clean up radionuclides and heavy metals in mixed wastes at U.S. Department of Energy Sites around the county? State regulators met together for five days over two months to learn about bioremediation technology and develop a consensus report of their recommendations regarding state regulatory concerns. In summary we found that panel members: - quickly grasped the science related to bioremediation and were able to effectively interact with scientists working on complicated issues related to the development and implementation of the technology; - are generally accepting of in situ bioremediation, but concerned about costs, implementation (e.g., institutional controls), and long-term effectiveness of the technology; - are concerned equally about technological and implementation issues; and - believed that the consensus workshop approach to learning about bioremediation was appropriate and useful. Finally, regulators wanted decision makers at US DOE to know they are willing to work with DOE regarding innovative approaches to clean-up at their sites, and consider a strong relationship between states and the DOE as critical to any effective clean-up. They do not want perceive themselves to be and do not want others to perceive them as barriers to successful clean-up at their sites.

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

    Directory of Open Access Journals (Sweden)

    Kelly Polido Kaneshiro Olympio

    2009-06-01

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

  12. "Final Report for Grant No. DE-FG02-97ER62492 "Engineering Deinococcus radiodurans for Metal Remediation in Radioactive Mixed Waste Sites"

    Energy Technology Data Exchange (ETDEWEB)

    Michael J. Daly, Ph.D.

    2005-03-17

    The groundwater and sediments of numerous U. S. Department of Energy (DOE) field sites are contaminated with mixtures of heavy metals (e.g., Hg, Cr, Pd) and radionuclides (e.g., U, Tc), as well as the fuel hydrocarbons benzene, toluene, ethylbenzene and xylenes (BTEX); chlorinated hydrocarbons, such as trichloroethylene (TCE); and polychlorinated biphenyls (PCBs). The remediation of such mixed wastes constitutes an immediate and complex waste management challenge for DOE, particularly in light of the costliness and limited efficacy of current physical and chemical strategies for treating mixed wastes. In situ bioremediation via natural microbial processes (e.g., metal reduction) remains a potent, potentially cost-effective approach to the reductive immobilization or detoxification of environmental contaminants. Seventy million cubic meters of soil and three trillion liters of groundwater have been contaminated by leaking radioactive waste generated in the United States during the Cold War. A cleanup technology is being developed based on the extremely radiation resistant bacterium Deinococcus radiodurans. Our recent isolation and characterization of D. radiodurans from a variety of DOE environments, including highly radioactive sediments beneath one of the leaking tanks (SX-108) at the Hanford Site in south-central Washington state, underscores the potential for this species to survive in such extreme environments. Research aimed at developing D. radiodurans for metal remediation in radioactive waste sites was started by this group in September 1997 with support from DOE NABIR grant DE-FG02-97ER62492. Our grant was renewed for the period 2000-2003, which includes work on the thermophilic radiation resistant bacterium Deinococcus geothermalis. Work funded by the existing grant contributed to 18 papers in the period 1997-2004 on the fundamental biology of D. radiodurans and its design for bioremediation of radioactive waste environments. Our progress since September

  13. Assisted phytoremediation of mixed metal(loid)-polluted pyrite waste: effects of foliar and substrate IBA application on fodder radish.

    Science.gov (United States)

    Vamerali, Teofilo; Bandiera, Marianna; Hartley, William; Carletti, Paolo; Mosca, Giuliano

    2011-06-01

    Exogenous application of plant-growth promoting substances may potentially improve phytoremediation of metal-polluted substrates by increasing shoot and root growth. In a pot-based study, fodder radish (Raphanus sativus L. var. oleiformis Pers.) was grown in As-Zn-Cu-Co-Pb-contaminated pyrite waste, and treated with indolebutyric acid (IBA) either by foliar spraying (10 mgL(-1)), or by direct application of IBA to the substrate (0.1 and 1 mgkg(-1)) in association, or not, with foliar spraying. With the exception of foliar spraying, IBA reduced above-ground biomass, whilst direct application of IBA to the substrate surface reduced root biomass (-59%). Trace element concentrations were generally increased, but removals (mg per plant) greatly reduced with IBA application, together with greater metal leaching from the substrate. It is concluded that, in our case, IBA had a negative effect on plant growth and phytoextraction of trace elements, possibly due to unsuitable root indoleacetic acid concentration following soil IBA application, the direct chelating effect of IBA and the low microbial activity in the pyrite waste affecting its breakdown.

  14. Mixed ligand complexation of some transition metal ions in solution and solid state: Spectral characterization, antimicrobial, antioxidant, DNA cleavage activities and molecular modeling

    Science.gov (United States)

    Shobana, Sutha; Dharmaraja, Jeyaprakash; Selvaraj, Shanmugaperumal

    2013-04-01

    Equilibrium studies of Ni(II), Cu(II) and Zn(II) mixed ligand complexes involving a primary ligand 5-fluorouracil (5-FU; A) and imidazoles viz., imidazole (him), benzimidazole (bim), histamine (hist) and L-histidine (his) as co-ligands(B) were carried out pH-metrically in aqueous medium at 310 ± 0.1 K with I = 0.15 M (NaClO4). In solution state, the stoichiometry of MABH, MAB and MAB2 species have been detected. The primary ligand(A) binds the central M(II) ions in a monodentate manner whereas him, bim, hist and his co-ligands(B) bind in mono, mono, bi and tridentate modes respectively. The calculated Δ log K, log X and log X' values indicate higher stability of the mixed ligand complexes in comparison to binary species. Stability of the mixed ligand complex equilibria follows the Irving-Williams order of stability. In vitro biological evaluations of the free ligand(A) and their metal complexes by well diffusion technique show moderate activities against common bacterial and fungal strains. Oxidative cleavage interaction of ligand(A) and their copper complexes with CT DNA is also studied by gel electrophoresis method in the presence of oxidant. In vitro antioxidant evaluations of the primary ligand(A), CuA and CuAB complexes by DPPH free radical scavenging model were carried out. In solid, the MAB type of M(II)sbnd 5-FU(A)sbnd his(B) complexes were isolated and characterized by various physico-chemical and spectral techniques. Both the magnetic susceptibility and electronic spectral analysis suggest distorted octahedral geometry. Thermal studies on the synthesized mixed ligand complexes show loss of coordinated water molecule in the first step followed by decomposition of the organic residues subsequently. XRD and SEM analysis suggest that the microcrystalline nature and homogeneous morphology of MAB complexes. Further, the 3D molecular modeling and analysis for the mixed ligand MAB complexes have also been carried out.

  15. Removal of fluoride impurities from UF.sub.6 gas

    Science.gov (United States)

    Beitz, James V.

    1985-01-01

    A method of purifying a UF.sub.6 gas stream containing one or more metal fluoride impurities composed of a transuranic metal, transition metal or mixtures thereof, is carried out by contacting the gas stream with a bed of UF.sub.5 in a reaction vessel under conditions where at least one impurity reacts with the UF.sub.5 to form a nongaseous product and a treated gas stream, and removing the treated gas stream from contact with the bed. The nongaseous products are subsequently removed in a reaction with an active fluorine affording agent to form a gaseous impurity which is removed from the reaction vessel. The bed of UF.sub.5 is formed by the reduction of UF.sub.6 in the presence of UV light. One embodiment of the reaction vessel includes a plurality of UV light sources as tubes on which UF.sub.5 is formed.

  16. Hydrothermal chemistry, structures, and luminescence studies of alkali hafnium fluorides.

    Science.gov (United States)

    Underwood, Christopher C; McMillen, Colin D; Chen, Hongyu; Anker, Jeffery N; Kolis, Joseph W

    2013-01-07

    This paper describes the hydrothermal chemistry of alkali hafnium fluorides, including the synthesis and structural characterization of five new alkali hafnium fluorides. Two ternary alkali hafnium fluorides are described: Li(2)HfF(6) in space group P31m with a = 4.9748(7) Å and c = 4.6449(9) Å and Na(5)Hf(2)F(13) in space group C2/m with a = 11.627(2) Å, b = 5.5159(11) Å, and c = 8.4317(17) Å. Three new alkali hafnium oxyfluorides are also described: two fluoroelpasolites, K(3)HfOF(5) and (NH(4))(3)HfOF(5), in space group Fm3m with a = 8.9766(10) and 9.4144(11) Å, respectively, and K(2)Hf(3)OF(12) in space group R3m with a = 7.6486(11) Å and c = 28.802(6) Å. Infrared (IR) spectra were obtained for the title solids to confirm the structure solutions. Comparison of these materials was made based on their structures and synthesis conditions. The formation of these species in hydrothermal fluids appears to be dependent upon both the concentration of the alkali fluoride mineralizer solution and the reaction temperature. Both X-ray and visible fluorescence studies were conducted on compounds synthesized in this study and showed that fluorescence was affected by a variety of factors, such as alkali metal size, the presence/absence of oxygen in the compound, and the coordination environment of Hf(4+).

  17. Electrochemical studies on cerium(Ⅲ) in molten fluoride mixtures

    Institute of Scientific and Technical Information of China (English)

    VIRGIL; CONSTANTIN; ANA-MARIA; POPESCU; MIRCEA; OLTEANU

    2010-01-01

    This study aims to determine the principal electrochemical characteristics of the electrodeposition of cerium metal from molten fluoride systems.The cathodic process of Ce3+ ions in LiF-NaF and LiF-NaF-CaF2 molten salts was studied using electrochemical techniques as steady state and cyclic voltammetry methods.The decomposition potential(Ed) and the overvoltage(η) were determined for NaCeF4 using current-potential curves under galvanostatic conditions.The Ed was found to be 2.025 V in LiF-NaF and 2.045 V in...

  18. Fluorescent Sensing of Fluoride in Cellular System

    Science.gov (United States)

    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

  19. Metal-fluxes characterization at a catchment scale: Study of mixing processes and end-member analysis in the Meca River watershed (SW Spain)

    Science.gov (United States)

    Cánovas, C. R.; Macías, F.; Olías, M.; López, R. Pérez; Nieto, J. M.

    2017-07-01

    Fluxes of acidity and contaminants from acid mine drainage (AMD) sources to the receiving surface water bodies were studied in a mining-impacted watershed (Meca River, SW Spain) using a novel methodology based on the joint application of EMMA and MIX codes. The application of EMMA and elemental ratios allowed delimiting the end-members responsible for water quality variations at a catchment scale. The further application of MIX quantified the significant impact of AMD on the river quality; less than 10% of AMD relative contribution is enough to maintain acidic conditions during most of the year. The mixing model also provided information about the element mobility, distinguishing those elements with a quasi-conservative behavior (e.g., Cu, Zn, Al, Co or Ni) from those affected by mineral precipitation/dissolution (e.g., K, Si, Na, Sr, Ca, Fe, Pb, or As). Floods are the main driver of dissolved and, mainly particulate, contaminants in the catchment. Thus, the first rainfall events in November only accounted for 19% of the annual Meca flow but yielded between 26 and 43% of the net acidity and dissolved metal loads (mainly, Fe, As and Pb). Concerning particulate transport, around 332 tons of particulate Fe, 49 tons of Al, 0.79 tons of As and 0.37 tons of Pb were recorded during these first floods. The particulate As concentration can be up to 34 times higher than the dissolved one during floods and between 2 and 4 times higher for Fe, Pb and Cr. This integrated modeling approach could be a promising and useful tool to face future restoration plans in derelict mines worldwide. This approach would allow prioritizing remedial measures, achieving an environmental and cost-effective restoration of degraded areas.

  20. The bioaccumulation of heavy metals in barley (Hordeum vulgare L cultivated on fly ash dump mixed with compost and natural zeolite materials

    Directory of Open Access Journals (Sweden)

    Smaranda Mâșu

    2012-10-01

    Full Text Available The physic-chemical characteristics of the upper layers of fly ash dumps are very important when phytostabilizationplant selection is carried out. Plants with topsoil well developed roots, like cereals are used to stabilize fly ash dumpsin order to eliminate the deflation, erosion, etc. These plant species could be used in thephytostabilization/phytoextraction variant taking into account their metal hyper accumulation capacity, and also inphytostabilization variant by adequate topsoil treatments when a decrease mobility of metals from soil to plants isachieved and thus a less toxic crop is obtained. This study presents a comparative analysis of the metalbioaccumulation degree in plant tissues (grain and straw of barley cultivated on fly ash variants treated withdifferent quantities of compost in the absence/presence of natural zeolite materials, indigenous volcanic tuff. Theaddition of plant debris and sewage sludge compost mixed with natural zeolite materials has lowered thebioaccumulation of Cr with 49%, of Cu with 29%, Fe with more than 77.5%, in grains and straw when compared tountreated fly ash. Barley plants does not allow for Pb and Ni transfer from the fly ash in the aerial part of tissue.

  1. Stability Constants of Mixed Ligand Complexes of Transition Metal(II Ions with Salicylidene-4-methoxyaniline as Primary Ligand and 5-Bromosalicylidene-4-nitroaniline as Secondary Ligand

    Directory of Open Access Journals (Sweden)

    N. G. Nadkarni

    2011-01-01

    Full Text Available Binary and ternary complexes of the type M-Y and M-X-Y [M = Mn(II, Ni(II, Cu(II and Zn(II; X = salicylidene-4-methoxyaniline and Y=5-bromosalicylidene-4-nitroaniline] have been examined pH-metrically at 27±0.5 °C and at constant ionic strength, μ= 0.1 M (KCl in 75 : 25(v/v 1,4-dioxne-water medium. The stability constants for binary (M-Y and ternary (M-X-Y systems were calculated. The relative stability (Δ log KT values of the ternary complexes with corresponding binary complexes for all the metal(II ions in the present study found to be negative indicating that ternary 1:1:1 (M-X-Y complexes are less stable than binary 1:1 (M-Y complexes. In the ternary system studied, the order of stability constants of mixed ligand complexes with respect to the metal ions was found to be Cu(II > NI(II > Mn(II > Zn(II; which is same as in the corresponding binary (M-Y systems.

  2. First stars VI - Abundances of C, N, O, Li, and mixing in extremely metal-poor giants. Galactic evolution of the light elements

    CERN Document Server

    Spite, M; Plez, B; Hill, V; Spite, F; Depagne, E; François, P; Bonifacio, P; Barbuy, B; Beers, T; Andersen, J; Molaro, P; Nordström, B; Primas, F

    2004-01-01

    We have investigated the poorly-understood origin of nitrogen in the early Galaxy by determining N abundances in 35 extremely metal-poor halo giants (22 stars have [Fe/H]<-3.0) using the C and O abundances determined in Paper V. Because any dredge-up of CNO processed material to the surface may complicate the interpretation of CNO abundances in giants, we have also measured the surface abundance of lithium. Our sample shows a clear dichotomy between two groups of stars. The first group shows evidence of C to N conversion through CN cycling and strong Li dilution, a signature of mixing. The second group shows no evidence for C to N conversion, and Li is only moderately diluted, and we conclude that their C and N abundances are very close to those of the gas from which they formed in the early Galaxy. These "unmixed" stars reflect the abundances in the early Galaxy: the [C/Fe] ratio is constant (about +0.2 dex) and the [C/Mg] ratio is close to solar at low metallicity, favouring a high C production by massiv...

  3. Comparative Evaluation of Longevity of Fluoride Release From three Different Fluoride Varnishes – An Invitro Study

    Science.gov (United States)

    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 (pVarnish released consistently and substantially more fluoride than other tested products. PMID:27656559

  4. Fluoride intake and its safety among heavy tea drinkers in a British fluoridated city.

    Science.gov (United States)

    Jenkins, G N

    1991-01-01

    Tea-drinking in very young children has been studied in a British city. The results suggested that the fluoride in tea would, in some cases, be sufficient to influence caries. Clinical findings to some extent supported this. The main purpose of the investigation reported here was to determine maximum possible fluoride intake in adults who were heavy tea drinkers in a fluoridated city and relate it to toxic thresholds. Heavy tea drinkers were traced through Health Visitors and voluntary organizations and the volumes and fluoride concentrations of their drinks were measured. Even the highest intake found (9 mg) is below the probable intake in Bartlett, Texas (8 ppm of fluoride), in relation to which no undesirable symptoms have been reported (Leone et al. 1954). This confirms the safety of fluoridation. The effects on fluoride concentration of evaporating soft and hard fluoride-containing waters to small bulk were compared. The results showed ceilings of 3 ppm of fluoride in hard water and about 14 ppm in soft water, much higher than the levels expected on the basis of the usually stated solubility of CaF2 (16 or 8 ppm of fluoride). However, under normal household conditions, it is most unlikely that dangerous levels of fluoride would be ingested from boiled water.

  5. Simulating Ru L3-edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers

    Energy Technology Data Exchange (ETDEWEB)

    Van Kuiken, Benjamin E.; Valiev, Marat; Daifuku, Stephanie L.; Bannan, Caitlin; Strader, Matthew L.; Cho, Hana; Huse, N.; Schoenlein, R. W.; Govind, Niranjan; Khalil, Munira

    2013-05-01

    Ruthenium L2,3-edge X-ray absorption (XA) spectroscopy probes transitions from core 2p orbitals to the 4d levels of the atom and is a powerful tool for interrogating the local electronic and molecular structure around the metal atom. However, a molecular-level interpretation of the Ru L2,3-edge spectral lineshapes is often complicated by spin–orbit coupling (SOC) and multiplet effects. In this study, we develop spin-free time-dependent density functional theory (TDDFT) as a viable and predictive tool to simulate the Ru L3-edge spectra. We successfully simulate and analyze the ground state Ru L3-edge XA spectra of a series of RuII and RuIII complexes: [Ru(NH3)6]2+/3+, [Ru(CN)6]4-/3-, [RuCl6]4-/3-, and the ground (1A1) and photoexcited (3MLCT) transient states of [Ru(bpy)3]2+ and Ru(dcbpy)2(NCS)2 (termed N3). The TDDFT simulations reproduce all the experimentally observed features in Ru L3-edge XA spectra. The advantage of using TDDFT to assign complicated Ru L3-edge spectra is illustrated by its ability to identify ligand specific charge transfer features in complex molecules. We conclude that the B3LYP functional is the most reliable functional for accurately predicting the location of charge transfer features in these spectra. Experimental and simulated Ru L3-edge XA spectra are presented for the transition metal mixed-valence dimers [(NC)5MII-CN-RuIII(NH3)5]- (where M = Fe or Ru) dissolved in water. We explore the spectral signatures of electron delocalization in Ru L3-edge XA spectroscopy and our simulations reveal that the inclusion of explicit solvent molecules is crucial for reproducing the experimentally determined valencies, highlighting the importance of the role of the solvent in transition metal charge transfer chemistry.

  6. Coordination and metalation bifunctionality of Cu with 5,10,15,20-tetra(4-pyridyl)porphyrin: toward a mixed-valence two-dimensional coordination network.

    Science.gov (United States)

    Li, Yang; Xiao, Jie; Shubina, Tatyana E; Chen, Min; Shi, Ziliang; Schmid, Martin; Steinrück, Hans-Peter; Gottfried, J Michael; Lin, Nian

    2012-04-11

    We investigated the coordination self-assembly and metalation reaction of Cu with 5,10,15,20-tetra(4-pyridyl)porphyrin (2HTPyP) on a Au(111) surface by means of scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory calculations. 2HTPyP was found to interact with Cu through both the peripheral pyridyl groups and the porphyrin core. Pairs of pyridyl groups from neighboring molecules coordinate Cu(0) atoms, which leads to the formation of a supramolecular metal-organic coordination network. The network formation occurs at room temperature; annealing at 450 K enhances the process. The interaction of Cu with the porphyrin core is more complex. At room temperature, formation of an initial complex Cu(0)-2HTPyP is observed. Annealing at 450 K activates an intramolecular redox reaction, by which the coordinated Cu(0) is oxidized to Cu(II) and the complex Cu(II)TPyP is formed. The coordination network consists then of Cu(II) complexes linked by Cu(0) atoms; that is, it represents a mixed-valence two-dimensional coordination network consisting of an ordered array of Cu(II) and Cu(0) centers. Above 520 K, the network degrades and the Cu atoms in the linking positions diffuse into the substrate, while the Cu(II)TPyP complexes form a close-packed structure that is stabilized by weak intermolecular interactions. Density functional theory investigations show that the reaction with Cu(0) proceeds via formation of an initial complex between metal atom and porphyrin followed by formation of Cu(II) porphyrin within the course of the reaction. The activation barrier of the rate limiting step was found to be 24-37 kcal mol(-1) depending on the method used. In addition, linear coordination of a Cu atom by two CuTPyP molecules is favorable according to gas-phase calculations. © 2012 American Chemical Society

  7. Review on fluoride, with special emphasis on calcium fluoride mechanisms in caries prevention.

    Science.gov (United States)

    ten Cate, J M

    1997-10-01

    Low concentrations of fluoride have a beneficial effect on enamel and dentin de- and remineralization. After fluoride treatments, such as topical applications, rinses or dentifrices, salivary fluoride concentrations decrease exponentially in a biphasic manner to very low concentrations within a few hours. For treatments to be effective over periods longer than the brushing and the following salivary clearance, fluoride needs to be deposited and slowly released. Calcium fluoride (or like) deposits act in such a way, owing to a surface covering of phosphate and/or proteins, which makes the CaF2 less soluble under in vivo conditions than in a pure form in inorganic solutions. Moreover, due to the phosphate groups on the surface of the calcium fluoride globules, fluoride is assumed to be released with decreasing pH when the phosphate groups are protonated in the dental plaque.

  8. Preparation, characterization and cytotoxicity studies of some transition metal complexes with ofloxacin and 1,10-phenanthroline mixed ligand

    Science.gov (United States)

    Sadeek, S. A.; El-Hamid, S. M. Abd

    2016-10-01

    [Zn(Ofl)(Phen)(H2O)2](CH3COO)·2H2O (1), [ZrO(Ofl)(Phen)(H2O)]NO3·2H2O (2) and [UO2(Ofl)(Phen)(H2O)](CH3COO)·H2O (3) complexes of fluoroquinolone antibacterial agent ofloxacin (HOfl), containing a nitrogen donor heterocyclic ligand, 1,10-phenathroline monohydrate (Phen), were prepared and their structures were established with the help of elemental analysis, molar conductance, magnetic properties, thermal studies and different spectroscopic studies like IR, UV-Vis., 1H NMR and Mass. The IR data of HOfl and Phen ligands suggested the existing of a bidentate binding involving carboxylate O and pyridone O for HOfl ligand and two pyridine N atoms for Phen ligand. The coordination geometries and electronic structures are determined from electronic absorption spectra and magnetic moment measurements. From molar conductance studies reveals that metal complexes are electrolytes and of 1:1 type. The calculated bond length and force constant, F(Udbnd O), in the uranyl complex are 1.751 Å and 641.04 Nm-1. The thermal properties of the complexes were investigated by thermogravimetry (TGA) technique. The activation thermodynamic parameters are calculated using Coats-Redfern and Horowitz-Metzger methods. Antimicrobial activity of the compounds was evaluated against some bacteria and fungi species. The activity data show that most metal complexes have antibacterial activity than that of the parent HOfl drug. The in vitro cytotoxicities of ligands and their complexes were also evaluated against human breast and colon carcinoma cells.

  9. Fast, selective adsorption of Cu{sup 2+} from aqueous mixed metal ions solution using 1,4,7-triazacyclononane modified SBA-15 silica adsorbent (SBA-TACN)

    Energy Technology Data Exchange (ETDEWEB)

    Tapaswi, Pradip Kumar; Moorthy, Madhappan Santha; Park, Sung Soo; Ha, Chang-Sik, E-mail: csha@pnu.edu

    2014-03-15

    A new SBA-15 supported 1,4,7-triazacyclononane modified mesoporous silica adsorbent (SBA-TACN) has been synthesized using post grafting route and has thoroughly been characterized by small angle X-ray scattering (SAXS), N{sub 2} adsorption–desorption measurements, Fourier-transform infrared (FT-IR), solid-state {sup 29}Si MAS and {sup 13}C CP MAS NMR spectroscopy, transmission electron (TEM) and scanning electron microscopy (SEM), elemental analysis (EA) and thermogravimetric analysis (TGA). The synthesized material shows excellent copper (II) ion adsorption selectivity at pH 5 in mixed metal ion solution containing Cu{sup 2+}, Cr{sup 3+}, Ni{sup 2+}, Co{sup 2+} and Li{sup +}. The copper ion adsorption capacity of the SBA-TACN can reach a maximum value of 0.67 mmol/g. Possible adsorption mechanism of metal ions on SBA-TACN has been discussed. The adsorbent can be readily regenerated by HNO{sub 3}–NH{sub 3} treatment. -- Graphical abstract: A new SBA-15 supported 1,4,7-triazacyclononane (TACN) modified mesoporous silica (SBA-TACN) adsorbent has been developed which shows excellent selectivity in Cu{sup 2+} adsorption from aqueous mixed metal ion solutions at pH 5. The copper ion adsorption capacity of the SBA-TACN can reach a maximum value of 0.67 mmol/g. The adsobent is stable enough to be used atleast for three cycles. Highlights: • Synthesis of a new TACN modified mesoporous silica SBA-15 type adsorbent. • The density of 1,4,7-triazacyclononane on SBA-15 is 1.22 mmol/g. • First report on the selective Cu{sup 2+} adsorption by TACN modified mesoporous silica. • Cu{sup 2+} adsorption capacity of the SBA-TACN can reach a maximum value of 0.67 mmol/g. • Potential candidate for selective removal of Cu{sup 2+} from contaminated water samples.

  10. "Final Report for Grant No. DE-FG02-97ER62492 "Engineering Deinococcus radiodurans for Metal Remediation in Radioactive Mixed Waste Sites"

    Energy Technology Data Exchange (ETDEWEB)

    Michael J. Daly, Ph.D.

    2005-03-17

    The groundwater and sediments of numerous U. S. Department of Energy (DOE) field sites are contaminated with mixtures of heavy metals (e.g., Hg, Cr, Pd) and radionuclides (e.g., U, Tc), as well as the fuel hydrocarbons benzene, toluene, ethylbenzene and xylenes (BTEX); chlorinated hydrocarbons, such as trichloroethylene (TCE); and polychlorinated biphenyls (PCBs). The remediation of such mixed wastes constitutes an immediate and complex waste management challenge for DOE, particularly in light of the costliness and limited efficacy of current physical and chemical strategies for treating mixed wastes. In situ bioremediation via natural microbial processes (e.g., metal reduction) remains a potent, potentially cost-effective approach to the reductive immobilization or detoxification of environmental contaminants. Seventy million cubic meters of soil and three trillion liters of groundwater have been contaminated by leaking radioactive waste generated in the United States during the Cold War. A cleanup technology is being developed based on the extremely radiation resistant bacterium Deinococcus radiodurans. Our recent isolation and characterization of D. radiodurans from a variety of DOE environments, including highly radioactive sediments beneath one of the leaking tanks (SX-108) at the Hanford Site in south-central Washington state, underscores the potential for this species to survive in such extreme environments. Research aimed at developing D. radiodurans for metal remediation in radioactive waste sites was started by this group in September 1997 with support from DOE NABIR grant DE-FG02-97ER62492. Our grant was renewed for the period 2000-2003, which includes work on the thermophilic radiation resistant bacterium Deinococcus geothermalis. Work funded by the existing grant contributed to 18 papers in the period 1997-2004 on the fundamental biology of D. radiodurans and its design for bioremediation of radioactive waste environments. Our progress since September

  11. FLUORIDE LEVELS IN COMMERCIALLY AVAILABLE RICE IN ...

    African Journals Online (AJOL)

    Preferred Customer

    2013-05-05

    May 5, 2013 ... There are several studies reporting the dietary intake of fluoride from water, ..... fluoride in rice samples showed the trend BR > ERR > NERICA > JR > RR > EWR. .... in cooked rice in Iran ranged from 0.2-1.6 mg F/kg [2].

  12. HOUSEHOLD PURIFICATION OF FLUORIDE CONTAMINATED MAGADI (TRONA)

    DEFF Research Database (Denmark)

    1997-01-01

    Purification of fluoride contaminated magadi is studied using bone char sorption and calcium precipitation. The bone char treatment is found to be workable both in columns and in batches where the magadi is dissolved in water prior to treatment. The concentrations in the solutions were 89 g magadi...... treatment method. A procedure for purification of fluoride contaminated magadi at household level is described....

  13. Inhibition of erosive wear by fluoride varnish

    NARCIS (Netherlands)

    Vieira, A.; Jager, D. H. J.; Ruben, J. L.; Huysmans, M. C. D. N. J. M.

    2007-01-01

    It has been suggested that fluoride products with a protective mechanical component are advantageous in the prevention of erosive wear. The aim of this study was to evaluate in situ the effect of fluoride varnish (FV) in the prevention of wear due to erosion and combined erosion and toothbrush abras

  14. Potentiometric Determination of Fluoride Concentration in Beers.

    Science.gov (United States)

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

    2017-04-26

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

  15. Inhibition of erosive wear by fluoride varnish

    NARCIS (Netherlands)

    Vieira, A.; Jager, D. H. J.; Ruben, J. L.; Huysmans, M. C. D. N. J. M.

    2007-01-01

    It has been suggested that fluoride products with a protective mechanical component are advantageous in the prevention of erosive wear. The aim of this study was to evaluate in situ the effect of fluoride varnish (FV) in the prevention of wear due to erosion and combined erosion and toothbrush

  16. Discovery of Interstellar Hydrogen Fluoride

    Science.gov (United States)

    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.

  17. Dipyridyl β-diketonate complexes and their use as metalloligands in the formation of mixed-metal coordination networks.

    Science.gov (United States)

    Burrows, Andrew D; Mahon, Mary F; Renouf, Catherine L; Richardson, Christopher; Warren, Anna J; Warren, John E

    2012-04-14

    The iron(III) and aluminium(III) complexes of 1,3-di(4-pyridyl)propane-1,3-dionato (dppd) and 1,3-di(3-pyridyl)propane-1,3-dionato (dmppd), [Fe(dppd)(3)] 1, [Fe(dmppd)(3)] 2, [Al(dppd)(3)] 3 and [Al(dmppd)(3)] 4 have been prepared. These complexes adopt molecular structures in which the metal centres contain distorted octahedral geometries. In contrast, the copper(II) and zinc(II) complexes [Cu(dppd)(2)] 5 and [Zn(dmppd)(2)] 6 both form polymeric structures in which coordination of the pyridyl groups into the axial positions of neighbouring metal centres links discrete square-planar complexes into two-dimensional networks. The europium complex [Eu(dmppd)(2)(H(2)O)(4)]Cl·2EtOH·0.5H(2)O 7 forms a structure containing discrete cations that are linked into sheets through hydrogen bonds, whereas the lanthanum complex [La(dmppd)(3)(H(2)O)]·2H(2)O 8 adopts a one-dimensional network structure, connected into sheets by hydrogen bonds. The iron complexes 1 and 2 act as metalloligands in reactions with silver(I) salts, with the nature of the product depending on the counter-ions present. Thus, the reaction between 1 and AgBF(4) gave [AgFe(dppd)(3)]BF(4)·DMSO 9, in which the silver centres link the metalloligands into discrete nanotubes, whereas reactions with AgPF(6) and AgSbF(6) gave [AgFe(dppd)(3)]PF(6)·3.28DMSO 10 and [AgFe(dppd)(3)]SbF(6)·1.25DMSO 11, in which the metalloligands are linked into sheets. In all three cases, only four of the six pyridyl groups present on the metalloligands are coordinated. The reaction between 2 and AgNO(3) gave [Ag(2)Fe(dmppd)(3)(ONO(2))]NO(3)·MeCN·CH(2)Cl(2)12. Compound 12 adopts a layer structure in which all pyridyl groups are coordinated to silver centres and, in addition, a nitrate ion bridges between two silver centres. A similar structure is adopted by [Ag(2)Fe(dmppd)(3)(O(2)CCF(3))]CF(3)CO(2)·2MeCN·0.25CH(2)Cl(2)13, with a bridging trifluoroacetate ion playing the same role as the nitrate ion in 12.

  18. Fluoride Importance in Controlling Caries and Fluorosis

    Directory of Open Access Journals (Sweden)

    Gaurav Solanki

    2012-04-01

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

  19. Diethylenetriaminium hexafluoridotitanate(IV fluoride

    Directory of Open Access Journals (Sweden)

    J. Lhoste

    2008-11-01

    Full Text Available The title compound, (C6H21N4[TiF6]F, was synthesized by the reaction of TiO2, tris(2-aminoethylamine, HF and ethanol at 463 K in a microwave oven. The crystal structure consists of two crystallographically independent [TiF6]2− anions, two fluoride anions and two triply-protonated tris(2-aminoethylamine cations. The Ti atoms are coordinated by six F atoms within slightly distorted octahedra. The anions and cations are connected by intermolecular N—H...F hydrogen bonds.

  20. Modeling and multi-objective optimization of powder mixed electric discharge machining process of aluminum/alumina metal matrix composite

    Directory of Open Access Journals (Sweden)

    Gangadharudu Talla

    2015-09-01

    Full Text Available Low material removal rate (MRR and high surface roughness values hinder large-scale application of electro discharge machining (EDM in the fields like automobile, aerospace and medical industry. In recent years, however, EDM has gained more significance in these industries as the usage of difficult-to-machine materials including metal matrix composites (MMCs increased. In the present work, an attempt has been made to fabricate and machine aluminum/alumina MMC using EDM by adding aluminum powder in kerosene dielectric. Results showed an increase in MRR and decrease in surface roughness (Ra compared to those for conventional EDM. Semi empirical models for MRR and Ra based on machining parameters and important thermo physical properties were established using a hybrid approach of dimensional and regression analysis. A multi response optimization was also performed using principal component analysis-based grey technique (Grey-PCA to determine optimum settings of process parameters for maximum MRR and minimum Ra within the experimental range. The recommended setting of process parameters for the proposed process has been found to be powder concentration (Cp = 4 g/l, peak current (Ip = 3 A, pulse on time (Ton = 150 μs and duty cycle (Tau = 85%.