PROCESS OF SEPARATING URANIUM FROM AQUEOUS SOLUTION BY SOLVENT EXTRACTION

DOEpatents

Warf, J.C.

1958-08-19

A process is described for separating uranium values from aqueous uranyl nitrate solutions. The process consists in contacting the uramium bearing solution with an organic solvent, tributyl phosphate, preferably diluted with a less viscous organic liquida whereby the uranyl nitrate is extracted into the organic solvent phase. The uranvl nitrate may be recovered from the solvent phase bv back extracting with an aqueous mediuin.

Rapid Dissolution of Soluble Uranyl Phases in Arid, Mine-Impacted Catchments Near Church Rock, NM

DOE Office of Scientific and Technical Information (OSTI.GOV)

deLemos, J.L.; Bostick, B.C.; Quicksall, A.N.

2009-05-14

We tested the hypothesis that runoff of uranium-bearing particles from mining waste disposal areas was a significant mechanism for redistribution of uranium in the northeastern part of the Upper Puerco River watershed (New Mexico). However, our results were not consistent with this hypothesis. Analysis of >100 sediment and suspended sediment samples collected adjacent to and downstream from uranium source areas indicated that uranium levels in the majority of the samples were not elevated above background. Samples collected within 50 m of a known waste disposal site were subjected to detailed geochemical characterization. Uranium in these samples was found to bemore » highly soluble; treatment with synthetic pore water for 24 h caused dissolution of 10-50% of total uranium in the samples. Equilibrium uranium concentrations in pore water were >4.0 mg/L and were sustained in repeated wetting events, effectively depleting soluble uranium from the solid phase. The dissolution rate of uranium appeared to be controlled by solid-phase diffusion of uranium from within uranium-bearing mineral particles. X-ray adsorption spectroscopy indicated the presence of a soluble uranyl silicate, and possibly a uranyl phosphate. These phases were exhausted in transported sediment suggesting that uranium was readily mobilized from sediments in the Upper Puerco watershed and transported in the dissolved load. These results could have significance for uranium risk assessment as well as mining waste management and cleanup efforts.« less

Rapid Dissolution of Soluble Uranyl Phases in Arid, Mine-Impacted Catchments near Church Rock, NM

PubMed Central

DELEMOS, JAMIE L.; BOSTICK, BENJAMIN C.; QUICKSALL, ANDREW N.; LANDIS, JOSHUA D.; GEORGE, CHRISTINE C.; SLAGOWSKI, NAOMI L.; ROCK, TOMMY; BRUGGE, DOUG; LEWIS, JOHNNYE; DURANT, JOHN L.

2008-01-01

We tested the hypothesis that runoff of uranium-bearing particles from mining waste disposal areas was a significant mechanism for redistribution of uranium in the northeastern part of the Upper Puerco River watershed (New Mexico). However, our results were not consistent with this hypothesis. Analysis of >100 sediment and suspended sediment samples collected adjacent to and downstream from uranium source areas indicated that uranium levels in the majority of the samples were not elevated above background. Samples collected within 50 m of a known waste disposal site were subjected to detailed geochemical characterization. Uranium in these samples was found to be highly soluble; treatment with synthetic pore water for 24 h caused dissolution of 10–50% of total uranium in the samples. Equilibrium uranium concentrations in pore water were >4.0 mg/L and were sustained in repeated wetting events, effectively depleting soluble uranium from the solid phase. The dissolution rate of uranium appeared to be controlled by solid-phase diffusion of uranium from within uranium-bearing mineral particles. X-ray adsorption spectroscopy indicated the presence of a soluble uranyl silicate, and possibly a uranyl phosphate. These phases were exhausted in transported sediment suggesting that uranium was readily mobilized from sediments in the Upper Puerco watershed and transported in the dissolved load. These results could have significance for uranium risk assessment as well as mining waste management and cleanup efforts. PMID:18589950

Bioaccumulation of nickel by intercalation into polycrystalline hydrogen uranyl phosphate deposited via an enzymatic mechanism.

PubMed

Bonthrone, K M; Basnakova, G; Lin, F; Macaskie, L E

1996-05-01

A Citrobacter sp. accumulates uranyl ion (UO2(2+)) as crystalline HUO2PO4.4H2O (HUP), using enzymatically generated inorganic phosphate. Ni was not removed by this mechanism, but cells already loaded with HUP removed Ni2+ by intercalative ion-exchange, forming Ni(UO2PO4)2.7H2O, as concluded by x-ray diffraction (XRD) and proton induced x-ray emission (PIXE) analyses. The loaded biomass became saturated with Ni rapidly, with a molar ratio of Ni:U in the cellbound deposit of approx. 1:6; Ni penetration was probably surface-localized. Cochallenge of the cells with Ni2+ and UO2(2+), and glycerol 2-phosphate (phosphate donor for phosphate release and metal bioprecipitation) gave sustained removal of both metals in a flow through bioreactor, with more extensively accumulated Ni. We propose 'Microbially Enhanced Chemisorption of Heavy Metals' (MECHM) to describe this hybrid mechanism of metal bioaccumulation via intercalation into preformed, biogenic crystals, and note also that MECHM can promote the removal of the transuranic radionuclide neptunium, which is difficult to achieve by conventional methods.

Proteogenomic insights into uranium tolerance of a Chernobyl's Microbacterium bacterial isolate.

PubMed

Gallois, Nicolas; Alpha-Bazin, Béatrice; Ortet, Philippe; Barakat, Mohamed; Piette, Laurie; Long, Justine; Berthomieu, Catherine; Armengaud, Jean; Chapon, Virginie

2018-04-15

Microbacterium oleivorans A9 is a uranium-tolerant actinobacteria isolated from the trench T22 located near the Chernobyl nuclear power plant. This site is contaminated with different radionuclides including uranium. To observe the molecular changes at the proteome level occurring in this strain upon uranyl exposure and understand molecular mechanisms explaining its uranium tolerance, we established its draft genome and used this raw information to perform an in-depth proteogenomics study. High-throughput proteomics were performed on cells exposed or not to 10μM uranyl nitrate sampled at three previously identified phases of uranyl tolerance. We experimentally detected and annotated 1532 proteins and highlighted a total of 591 proteins for which abundances were significantly differing between conditions. Notably, proteins involved in phosphate and iron metabolisms show high dynamics. A large ratio of proteins more abundant upon uranyl stress, are distant from functionally-annotated known proteins, highlighting the lack of fundamental knowledge regarding numerous key molecular players from soil bacteria. Microbacterium oleivorans A9 is an interesting environmental model to understand biological processes engaged in tolerance to radionuclides. Using an innovative proteogenomics approach, we explored its molecular mechanisms involved in uranium tolerance. We sequenced its genome, interpreted high-throughput proteomic data against a six-reading frame ORF database deduced from the draft genome, annotated the identified proteins and compared protein abundances from cells exposed or not to uranyl stress after a cascade search. These data show that a complex cellular response to uranium occurs in Microbacterium oleivorans A9, where one third of the experimental proteome is modified. In particular, the uranyl stress perturbed the phosphate and iron metabolic pathways. Furthermore, several transporters have been identified to be specifically associated to uranyl stress, paving the way to the development of biotechnological tools for uranium decontamination. Copyright © 2017. Published by Elsevier B.V.

Potential New Ligand Systems for Binding Uranyl Ions in Seawater Environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arnold, John

2014-12-13

Work began this quarter on a new project involving a combined computational and biosynthetic approach to selective recognition of uranyl ion in aqueous solution. This project exploits the results of computational studies to discover new ligand classes. Synthetic studies will follow to generate target systems for uranyl binding and determination of binding constants. The process will be iterative, with results from computation informing synthesis, and vice versa. The theme of the ligand classes to be examined initially will be biologically based. New phosphonate-containing α-amino acid N-carboxyanhydride (NCA) monomers were used recently to prepare well-defined phosphonate-containing poly-peptides and block copolypeptides. Ourmore » first approach is to utilize these phosphate- and phosphonate-containing NCAs for the coordination of uranyl. The work includes the laboratory-scale preparation of a series of NCAs and the full thermodynamic and spectroscopic characterization of the resulting uranyl complexes. We are also evaluating the sequestering activity in different physiological and environmental conditions of these copolymers as well as their biodegradability.« less

Periodic density functional theory investigation of the uranyl ion sorption on three mineral surfaces: a comparative study.

PubMed

Roques, Jérôme; Veilly, Edouard; Simoni, Eric

2009-06-04

Canister integrity and radionuclides retention is of prime importance for assessing the long term safety of nuclear waste stored in engineered geologic depositories. A comparative investigation of the interaction of uranyl ion with three different mineral surfaces has thus been undertaken in order to point out the influence of surface composition on the adsorption mechanism(s). Periodic DFT calculations using plane waves basis sets with the GGA formalism were performed on the TiO(2)(110), Al(OH)(3)(001) and Ni(111) surfaces. This study has clearly shown that three parameters play an important role in the uranyl adsorption mechanism: the solvent (H(2)O) distribution at the interface, the nature of the adsorption site and finally, the surface atoms' protonation state.

Periodic Density Functional Theory Investigation of the Uranyl Ion Sorption on Three Mineral Surfaces: A Comparative Study

PubMed Central

Roques, Jérôme; Veilly, Edouard; Simoni, Eric

2009-01-01

Canister integrity and radionuclides retention is of prime importance for assessing the long term safety of nuclear waste stored in engineered geologic depositories. A comparative investigation of the interaction of uranyl ion with three different mineral surfaces has thus been undertaken in order to point out the influence of surface composition on the adsorption mechanism(s). Periodic DFT calculations using plane waves basis sets with the GGA formalism were performed on the TiO2(110), Al(OH)3(001) and Ni(111) surfaces. This study has clearly shown that three parameters play an important role in the uranyl adsorption mechanism: the solvent (H2O) distribution at the interface, the nature of the adsorption site and finally, the surface atoms’ protonation state. PMID:19582222

Performance of a hydrogen uranyl phosphate-carbon double-layer solid capacitor

NASA Astrophysics Data System (ADS)

Pham-Thi, M.; Adet, Ph.; Velasco, G.; Colomban, Ph.

1986-05-01

A mixture of commercially available carbon black (C) powders and hydrogen uranyl phosphate (HUP) precipitate can be used as the electrode material for miniaturized double-layer capacitors. A solid cell of C-HUP/HUP/C-HUP has a capacitance of 1 F which, given the device area and thickness of 0.8 sq cm and 0.2 cm respectively, corresponds to an energy density of more than 5 J/cu cm. The charge x voltage factor is higher than 5 x 10 to the -6th s and the working voltage is over 1.6 V. The leakage current is lower than 3 microamps at room temperature. The electrolyte can be operated up to about 120 C if the device is hermetically sealed.

Interaction of Uranium with Bacterial Cell Surfaces: Inferences from Phosphatase-Mediated Uranium Precipitation.

PubMed

Kulkarni, Sayali; Misra, Chitra Seetharam; Gupta, Alka; Ballal, Anand; Apte, Shree Kumar

2016-08-15

Deinococcus radiodurans and Escherichia coli expressing either PhoN, a periplasmic acid phosphatase, or PhoK, an extracellular alkaline phosphatase, were evaluated for uranium (U) bioprecipitation under two specific geochemical conditions (GCs): (i) a carbonate-deficient condition at near-neutral pH (GC1), and (ii) a carbonate-abundant condition at alkaline pH (GC2). Transmission electron microscopy revealed that recombinant cells expressing PhoN/PhoK formed cell-associated uranyl phosphate precipitate under GC1, whereas the same cells displayed extracellular precipitation under GC2. These results implied that the cell-bound or extracellular location of the precipitate was governed by the uranyl species prevalent at that particular GC, rather than the location of phosphatase. MINTEQ modeling predicted the formation of predominantly positively charged uranium hydroxide ions under GC1 and negatively charged uranyl carbonate-hydroxide complexes under GC2. Both microbes adsorbed 6- to 10-fold more U under GC1 than under GC2, suggesting that higher biosorption of U to the bacterial cell surface under GC1 may lead to cell-associated U precipitation. In contrast, at alkaline pH and in the presence of excess carbonate under GC2, poor biosorption of negatively charged uranyl carbonate complexes on the cell surface might have resulted in extracellular precipitation. The toxicity of U observed under GC1 being higher than that under GC2 could also be attributed to the preferential adsorption of U on cell surfaces under GC1. This work provides a vivid description of the interaction of U complexes with bacterial cells. The findings have implications for the toxicity of various U species and for developing biological aqueous effluent waste treatment strategies. The present study provides illustrative insights into the interaction of uranium (U) complexes with recombinant bacterial cells overexpressing phosphatases. This work demonstrates the effects of aqueous speciation of U on the biosorption of U and the localization pattern of uranyl phosphate precipitated as a result of phosphatase action. Transmission electron microscopy revealed that location of uranyl phosphate (cell associated or extracellular) was primarily influenced by aqueous uranyl species present under the given geochemical conditions. The data would be useful for understanding the toxicity of U under different geochemical conditions. Since cell-associated precipitation of metal facilitates easy downstream processing by simple gravity-based settling down of metal-loaded cells, compared to cumbersome separation techniques, the results from this study are of considerable relevance to effluent treatment using such cells. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Interaction of Uranium with Bacterial Cell Surfaces: Inferences from Phosphatase-Mediated Uranium Precipitation

PubMed Central

Kulkarni, Sayali; Misra, Chitra Seetharam; Gupta, Alka; Ballal, Anand

2016-01-01

ABSTRACT Deinococcus radiodurans and Escherichia coli expressing either PhoN, a periplasmic acid phosphatase, or PhoK, an extracellular alkaline phosphatase, were evaluated for uranium (U) bioprecipitation under two specific geochemical conditions (GCs): (i) a carbonate-deficient condition at near-neutral pH (GC1), and (ii) a carbonate-abundant condition at alkaline pH (GC2). Transmission electron microscopy revealed that recombinant cells expressing PhoN/PhoK formed cell-associated uranyl phosphate precipitate under GC1, whereas the same cells displayed extracellular precipitation under GC2. These results implied that the cell-bound or extracellular location of the precipitate was governed by the uranyl species prevalent at that particular GC, rather than the location of phosphatase. MINTEQ modeling predicted the formation of predominantly positively charged uranium hydroxide ions under GC1 and negatively charged uranyl carbonate-hydroxide complexes under GC2. Both microbes adsorbed 6- to 10-fold more U under GC1 than under GC2, suggesting that higher biosorption of U to the bacterial cell surface under GC1 may lead to cell-associated U precipitation. In contrast, at alkaline pH and in the presence of excess carbonate under GC2, poor biosorption of negatively charged uranyl carbonate complexes on the cell surface might have resulted in extracellular precipitation. The toxicity of U observed under GC1 being higher than that under GC2 could also be attributed to the preferential adsorption of U on cell surfaces under GC1. This work provides a vivid description of the interaction of U complexes with bacterial cells. The findings have implications for the toxicity of various U species and for developing biological aqueous effluent waste treatment strategies. IMPORTANCE The present study provides illustrative insights into the interaction of uranium (U) complexes with recombinant bacterial cells overexpressing phosphatases. This work demonstrates the effects of aqueous speciation of U on the biosorption of U and the localization pattern of uranyl phosphate precipitated as a result of phosphatase action. Transmission electron microscopy revealed that location of uranyl phosphate (cell associated or extracellular) was primarily influenced by aqueous uranyl species present under the given geochemical conditions. The data would be useful for understanding the toxicity of U under different geochemical conditions. Since cell-associated precipitation of metal facilitates easy downstream processing by simple gravity-based settling down of metal-loaded cells, compared to cumbersome separation techniques, the results from this study are of considerable relevance to effluent treatment using such cells. PMID:27287317

A multi-instrumental geochemical study of anomalous uranium enrichment in coal.

PubMed

Havelcová, Martina; Machovič, Vladimír; Mizera, Jiří; Sýkorová, Ivana; Borecká, Lenka; Kopecký, Lubomír

2014-11-01

Contents of uranium in coals from Odeř in the northernmost part of the Sokolov Basin, Czech Republic, in the vicinity of the well known St. Joachimsthal uranium ore deposits, reach extremely high values. In the present work, coal samples with contents of uranium ranging from 0.02 to 6 wt.% were studied. The study employing a whole complex of analytical techniques has been aimed at identification of changes in the structure of coal organic matter, which are associated with the high contents of uranium in coal. The study includes proximate and ultimate analyses, multielement analysis by instrumental neutron and photon activation analyses, micropetrographic analysis by optical microscopy, ESEM/EDX analysis of mineral matter, infrared and Raman spectroscopies, solvent extraction followed by gas chromatography with mass spectroscopy (GC/MS), and analytical pyrolysis (Py-GC/MS). The study has confirmed previously proposed explanation of uraniferous mineralization in sedimentary carboniferous substances by the mechanism of reduction and fixation of soluble U(VI) (uranyl, UO2(2+)) species (e.g., humic, carbonate/hydroxo/phosphate complexes) by sedimentary organic matter under diagenetic or hydrothermal conditions, and formation of insoluble U(IV) species as phosphate minerals and uraninite. The process is accompanied with alteration and destruction of the coal organic matter. The changes in the structure of coal organic matter involve dehydrogenation and oxidation mainly in the aliphatic, aromatic and hydroxyl structures, and an increase in aromaticity, content of ether bonds, and the degree of coalification. Copyright © 2014 Elsevier Ltd. All rights reserved.

Additional studies on mixed uranyl oxide-hydroxide hydrate alteration products of uraninite from the palermo and ruggles granitic pegmatites, grafton county, New Hampshire

USGS Publications Warehouse

Foord, E.E.; Korzeb, S.L.; Lichte, F.E.; Fitzpatrick, J.J.

1997-01-01

Additional studies on an incompletely characterized secondary uranium "mineral" from the Ruggles and Palermo granitic pegmatites, New Hampshire, referred to as mineral "A" by Frondel (1956), reveal a mixture of schoepite-group minerals and related uranyl oxide-hydroxide hydrated compounds. A composite chemical analysis yielded (in wt.%): PbO 4.85 (EMP), UO3 83.5 (EMP), BaO 0.675 (av. of EMP and ICP), CaO 0.167 (av. of EMP and ICP), K2O 2.455 (av. of EMP and ICP), SrO 0.21 (ICP), ThO2 0.85 (ICP), H2O 6.9, ??99.61. Powder-diffraction X-ray studies indicate a close resemblance in patterns between mineral "A" and several uranyl oxide-hydroxide hydrated minerals, including the schoepite family of minerals and UO2(OH)2. The powder-diffraction data for mineral "A" are most similar to those for synthetic UO2.86??1.5H2O and UO2(OH)2, but other phases are likely present as well. TGA analysis of both mineral "A" and metaschoepite show similar weight-loss and first derivative curves. The dominant losses are at 100??C, with secondary events at 400?? and 600??C. IR spectra show the presence of (OH) and H2O. Uraninite from both pegmatites, analyzed by LAM-ICP-MS, shows the presence of Th, Pb, K and Ca.

Biosensing for the Environment and Defence: Aqueous Uranyl Detection Using Bacterial Surface Layer Proteins

PubMed Central

Conroy, David J.R.; Millner, Paul A.; Stewart, Douglas I.; Pollmann, Katrin

2010-01-01

The fabrication of novel uranyl (UO22+) binding protein based sensors is reported. The new biosensor responds to picomolar levels of aqueous uranyl ions within minutes using Lysinibacillus sphaericus JG-A12 S-layer protein tethered to gold electrodes. In comparison to traditional self assembled monolayer based biosensors the porous bioconjugated layer gave greater stability, longer electrode life span and a denser protein layer. Biosensors responded specifically to UO22+ ions and showed minor interference from Ni2+, Cs+, Cd2+ and Co2+. Chemical modification of JG-A12 protein phosphate and carboxyl groups prevented UO22+ binding, showing that both moieties are involved in the recognition to UO22+. PMID:22399904

Decrease of U(VI) Immobilization Capability of the Facultative Anaerobic Strain Paenibacillus sp. JG-TB8 under Anoxic Conditions Due to Strongly Reduced Phosphatase Activity

PubMed Central

Reitz, Thomas; Rossberg, Andre; Barkleit, Astrid; Selenska-Pobell, Sonja; Merroun, Mohamed L.

2014-01-01

Interactions of a facultative anaerobic bacterial isolate named Paenibacillus sp. JG-TB8 with U(VI) were studied under oxic and anoxic conditions in order to assess the influence of the oxygen-dependent cell metabolism on microbial uranium mobilization and immobilization. We demonstrated that aerobically and anaerobically grown cells of Paenibacillus sp. JG-TB8 accumulate uranium from aqueous solutions under acidic conditions (pH 2 to 6), under oxic and anoxic conditions. A combination of spectroscopic and microscopic methods revealed that the speciation of U(VI) associated with the cells of the strain depend on the pH as well as on the aeration conditions. At pH 2 and pH 3, uranium was exclusively bound by organic phosphate groups provided by cellular components, independently on the aeration conditions. At higher pH values, a part (pH 4.5) or the total amount (pH 6) of the dissolved uranium was precipitated under oxic conditions in a meta-autunite-like uranyl phosphate mineral phase without supplying an additional organic phosphate substrate. In contrast to that, under anoxic conditions no mineral formation was observed at pH 4.5 and pH 6, which was clearly assigned to decreased orthophosphate release by the cells. This in turn was caused by a suppression of the indigenous phosphatase activity of the strain. The results demonstrate that changes in the metabolism of facultative anaerobic microorganisms caused by the presence or absence of oxygen can decisively influence U(VI) biomineralization. PMID:25157416

Ferrihydrite in soils

NASA Astrophysics Data System (ADS)

Vodyanitskii, Yu. N.; Shoba, S. A.

2016-07-01

Ferrihydrite—an ephemeral mineral—is the most active Fe-hydroxide in soils. According to modern data, the ferrihydrite structure contains tetrahedral lattice in addition to the main octahedral lattice, with 10-20% of Fe being concentrated in the former. The presence of Fe tetrahedrons influences the surface properties of this mineral. The chemical composition of ferrihydrite samples depends largely on the size of lattice domains ranging from 2 to 6 nm. Chemically pure ferrihydrite rarely occurs in the soil; it usually contains oxyanion (SiO14 4-, PO4 3-) and cation (Al3+) admixtures. Aluminum replace Fe3+ in the structure with a decrease in the mineral particle size. Oxyanions slow down polymerization of Fe3+ aquahydroxomonomers due to the films at the surface of mineral nanoparticles. Si- and Al-ferrihydrites are more resistant to the reductive dissolution than the chemically pure ferrihydrite. In addition, natural ferrihydrite contains organic substance that decreases the grain size of the mineral. External organic ligands favor ferrihydrite dissolution. In the European part of Russia, ferrihydrite is more widespread in the forest soils than in the steppe soils. Poorly crystallized nanoparticles of ferrihydrite adsorb different cations (Zn, Cu) and anions (phosphate, uranyl, arsenate) to immobilize them in soils; therefore, ferrihydrite nanoparticles play a significant role in the biogeochemical cycle of iron and other elements.

Genesis of kasolite associated with aplite-pegmatite at Jabal Sayid, Hijaz region, Kingdom of Saudi Arabia

NASA Astrophysics Data System (ADS)

Dawood, Yehia H.; Harbi, Hesham M.; Abd El-Naby, Hamdy H.

2010-01-01

In this study, we report kasolite Pb(UO 2)SiO 4·(H 2O) for the first time as a main uranyl mineral in the mineralized aplite-pegmatite of Jabal Sayid, Hijaz region. It commonly forms clusters of yellow acicular crystals in the voids and fractures. The mineral chemistry and mineralogical characteristics of kasolite were investigated using different techniques. Calcium, iron and phosphorus are detected in kasolite in addition to its major constituents; uranium, lead and silicon. Lead does not exist as a radiogenic product and not even as a substitute for uranium in the mineral structure. Alternatively, galena mineralization could be considered as a source for lead. The fluoride and carbonate complexes played a significant role in the formation of kasolite. High temperature hydrothermal solutions reacted with pre-existing uranium-bearing metamictized accessory minerals such as pyrochlore, U-rich thorite and zircon to form uranous fluoride complexes. These complexes are predominant in reducing environment and at pH 4. When the fluids approached the surface passing through fracture system, the oxygen fugacity ( fO 2) and the pH increased because of the loss of volatile components. At these conditions, uranous fluorides would convert to uranyl fluoride complexes UO 2F 3-. Further decrease in temperature was associated with the decay of the activity of fluorine ion by the dilution of hydrothermal solutions and precipitation of fluorite. At this condition, uranyl-carbonate complexes are favoured. These complexes were combined later with silica and lead to form kasolite.

Failure of ESI Spectra to Represent Metal-Complex Solution Composition: A Study of Lanthanide-Carboxylate Complexes

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDonald, Luther W.; Campbell, James A.; Clark, Sue B.

2014-01-21

Electrospray ionization - mass spectrometry (ESI-MS) was used for the characterization of uranyl complexed to tributyl phosphate (TBP) and dibutyl phosphate (DBP). The stoichiometry of uranyl with TBP and DBP was determined, and the gas phase speciation was found to be dependent on the cone voltage applied to induce fragmentation on the gas phase complexes. To quantitatively compare the gas phase distribution of species to solution, apparent stability constants were calculated. With a cone voltage of 80V, the apparent stability constants for the complexes UO2(NO3)2•2TBP, UO2(NO3)2(H2O)•2TBP, and UO2(DBP)+ were determined. With a lower cone voltage applied, larger complexes were observedmore » and stability constants for the complexes UO2(NO3)2•3TBP and UO2(DBP)42- were determined.« less

Iron (III) Matrix Effects on Mineralization and Immobilization of Actinides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cynthia-May S. Gong; Tyler A. Sullens; Kenneth R. Czerwinski

2006-01-01

Abstract - A number of models for the Yucca Mountain Project nuclear waste repository use studies of actinide sorption onto well-defined iron hydroxide materials. In the case of a waste containment leak, however, a complex interaction between dissolved waste forms and failed containment vessel components can lead to immediate precipitation of migratory iron and uranyl in the silicate rich near-field environment. Use of the Fe(III) and UO22+ complexing agent acetohydroxamic acid (AHA) as a colorimetric agent for visible spectrophotometry is well-known. Using the second derivative of these spectra a distinct shift in iron complexation in the presence of silicate ismore » seen that is not seen with uranyl or alone. Silica also decreases the ability of uranyl and ferric solutions to absorb hydroxide, hastening precipitation. These ferric silicate precipitates are highly amorphous and soluble. Precipitates formed in the presence of uranyl below ~1 mol% exhibit lower solubility than precipitates from up to 50 mol % and of uranyl silicates alone.« less

Water structure and aqueous uranyl(VI) adsorption equilibria onto external surfaces of beidellite, montmorillonite, and pyrophyllite: results from molecular simulations.

PubMed

Greathouse, Jeffery A; Cygan, Randall T

2006-06-15

Molecular dynamics simulations were performed to provide a systematic study of aqueous uranyl adsorption onto the external surface of 2:1 dioctahedral clays. Our understanding of this key process is critical in predicting the fate of radioactive contaminants in natural groundwaters. These simulations provide atomistic detail to help explain experimental trends in uranyl adsorption onto natural media containing smectite clays. Aqueous uranyl concentrations ranged from 0.027 to 0.162 M. Sodium ions and carbonate ions (0.027-0.243 M) were also present in the aqueous regions to more faithfully model a stream of uranyl-containing groundwater contacting a mineral system comprised of Na-smectite. No adsorption occurred near the pyrophyllite surface, and there was little difference in uranyl adsorption onto the beidellite and montmorillonite, despite the difference in location of clay layer charge between the two. At low uranyl concentration, the pentaaquouranyl complex dominates in solution and readily adsorbs to the clay basal plane. At higher uranyl (and carbonate) concentrations, the mono(carbonato) complex forms in solution, and uranyl adsorption decreases. Sodium adsorption onto beidellite occurred both as inner- and outer-sphere surface complexes, again with little effect on uranyl adsorption. Uranyl surface complexes consisted primarily of the pentaaquo cation (85%) and to a lesser extent the mono(carbonato) species (15%). Speciation diagrams of the aqueous region indicate that the mono(carbonato)uranyl complex is abundant at high ionic strength. Oligomeric uranyl complexes are observed at high ionic strength, particularly near the pyrophyllite and montmorillonite surfaces. Atomic density profiles of water oxygen and hydrogen atoms are nearly identical near the beidellite and montmorillonite surfaces. Water structure therefore appears to be governed by the presence of adsorbed ions and not by the location of layer charge associated with the substrate. The water oxygen density near the pyrophyllite surface is similar to the other cases, but the hydrogen density profile indicates reduced hydrogen bonding between adsorbed water molecules and the surface.

A route to oligosaccharide-appended salicylaldehydes: useful building blocks for the synthesis of metal-salophen complexes.

PubMed

Bedini, Emiliano; Forte, Gianpiero; De Castro, Cristina; Parrilli, Michelangelo; Dalla Cort, Antonella

2013-08-16

A simple and general synthetic protocol to obtain oligosaccharide-appended salicylaldehydes, key intermediates for the synthesis of water-soluble metal-salophen complexes, is here reported. Six new aldehydes have been prepared and fully characterized as well as the corresponding zinc- and uranyl-salophen complexes. These new derivatives show very good solubility in water. Preliminary studies on the association of compound 19-U, that is, the uranyl maltotetraose derivative, with hydrogen phosphate and fluoride provide very encouraging results and open up the possibility of using such compounds for the efficient recognition of anions in pure water.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, Jesse D.; Bowden, Mark; Tom Resch, C.

2017-01-01

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

Effect of pH on uranium(VI) biosorption and biomineralization by Saccharomyces cerevisiae.

PubMed

Zheng, X Y; Shen, Y H; Wang, X Y; Wang, T S

2018-07-01

Biosorption of radionuclides by microorganisms is a promising and effective method for the remediation of contaminated areas. pH is the most important factor during uranium biosorption by Saccharomyces cerevisiae because the pH value not only affects the biosorption rate but also affects the precipitation structure. This study investigated the effect of pH on uranium (VI) biosorption and biomineralization by S. cerevisiae. Cells have the ability to buffer the solution to neutral, allowing the biosorption system to reach an optimal level regardless of the initial pH value. This occurs because there is a release of phosphate and ammonium ions during the interaction between cells and uranium. The uranyl and phosphate ions formed nano-particles, which is chernikovite H 2 (UO 2 ) 2 (PO 4 ) 2 ·8H 2 O (PDF #08-0296), on cell surface under the initial acidic conditions. However, under the initial alkaline conditions, the uranyl, phosphate and ammonium ions formed a large amount of scale-like precipitation, which is uramphite (NH 4 )(UO 2 )PO 4 ·3H 2 O (PDF #42-0384), evenly over on cell surface. Copyright © 2018 Elsevier Ltd. All rights reserved.

Study of Pulsed Columns with the System. Uranyl Nitrate-Nitric Acid-Water- Tributylphosphate; ETUDE DES COLONNES A PULSATIONS A L'AIDE DU SYSTEME NITRATE D'URANYLE-ACIDE NITRIQUEEAU-TRIBUTYLPHOSPHATE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Durandet, J.; Defives, D.; Choffe, B.

1959-10-31

The performsnce of a pulsed column with perforated plates was studied with the aid of a uranyl nitrate-nitric acid --water --tributyl phosphate system. The extraction of uranium from an aqueous acidic solution by an organic solvent and the extraction of uranium from organic solutions by water were the two cases investigated. The variation of the efficiency and the capacity of the pulsed column was determined as a function of the pulse amplitude and frequency, of the total flow rate, of the diameter of the holes, and of the choice of dispersed phase. The results showed that for a given amplitudemore » and total flow rate the efficiency has a maximum with an increase in frequency. (J.S.R.)« less

Identification of Uranium Minerals in Natural U-Bearing Rocks Using Infrared Reflectance Spectroscopy.

PubMed

Beiswenger, Toya N; Gallagher, Neal B; Myers, Tanya L; Szecsody, James E; Tonkyn, Russell G; Su, Yin-Fong; Sweet, Lucas E; Lewallen, Tricia A; Johnson, Timothy J

2018-02-01

The identification of minerals, including uranium-bearing species, is often a labor-intensive process using X-ray diffraction (XRD), fluorescence, or other solid-phase or wet chemical techniques. While handheld XRD and fluorescence instruments can aid in field applications, handheld infrared (IR) reflectance spectrometers can now also be used in industrial or field environments, with rapid, nondestructive identification possible via analysis of the solid's reflectance spectrum providing information not found in other techniques. In this paper, we report the use of laboratory methods that measure the IR hemispherical reflectance of solids using an integrating sphere and have applied it to the identification of mineral mixtures (i.e., rocks), with widely varying percentages of uranium mineral content. We then apply classical least squares (CLS) and multivariate curve resolution (MCR) methods to better discriminate the minerals (along with two pure uranium chemicals U 3 O 8 and UO 2 ) against many common natural and anthropogenic background materials (e.g., silica sand, asphalt, calcite, K-feldspar) with good success. Ground truth as to mineral content was attained primarily by XRD. Identification is facile and specific, both for samples that are pure or are partially composed of uranium (e.g., boltwoodite, tyuyamunite, etc.) or non-uranium minerals. The characteristic IR bands generate unique (or class-specific) bands, typically arising from similar chemical moieties or functional groups in the minerals: uranyls, phosphates, silicates, etc. In some cases, the chemical groups that provide spectral discrimination in the longwave IR reflectance by generating upward-going (reststrahlen) bands can provide discrimination in the midwave and shortwave IR via downward-going absorption features, i.e., weaker overtone or combination bands arising from the same chemical moieties.

Characterization of Uranium Tolerance and Biomineralization Potential of Caulobacter crescentus

NASA Astrophysics Data System (ADS)

Park, D.

2015-12-01

Due to its high toxicity and mobility, U(VI) poses a major environmental threat to ecosystems. The ubiquitous aerobic bacterium Caulobacter cresecentus is an attractive candidate for U(VI) bioremediation because of its ability to survive in low-nutrient environments (5, 6), tolerate high U concentrations and mineralize U(VI) aerobically through the formation of uranyl phosphate (U-Pi) precipitates. Despite these attractive environmental properties, both a systems level understanding of the adaptive response pathways involved in U tolerance and the environmental conditions affecting the biomineralization process and stability of biogenic U-Pi minerals remain limited. By measuring changes in both mRNA and protein expression during exposure to high U levels, we have identified the core stress response pathways involved in U tolerance. Pathways associated with heat shock, lipospolysaccharide biosynthesis and transport, outer membrane lipoprotein transport and outermembrane assembly were highly induced at both the RNA and protein levels. Correspondingly, removal of integral components of proteolysis pathways including clpA, clpS and degP significantly reduced U tolerance under biomineralization conditions. Surprisingly, in contrast to many other heavy metals, U did not cause oxidative stress or DNA damage. Together, these analyses indicate that U predominately targets the outermembrane and causes mis-folding of both cytoplasmic and extracytoplasmic proteins. Efforts are currently underway to characterize the morphological and structural properties of biogenic U-Pi minerals and the environmental factors that influence their production and stability. Preliminary AFM studies suggest that U-Pi minerals formed under biomineralization conditions appear morphologically distinct from those formed abiotically between U(VI) and inorganic phosphate. Additionally, we observed that biomineralization tolerates a wide pH range (pH 6-9). Our long-range goal is the development of a conceptual model of the role of microbes in U cycling under oxidizing conditions across the DOE complex, and ultimately, provide DOE with the scientific basis to support decisions for the remediation of legacy sites.

Uranium immobilization and nanofilm formation on magnesium-rich minerals

DOE PAGES

van Veelen, Arjen; Bargar, John R.; Law, Gareth T. W.; ...

2016-03-18

Polarization-dependent grazing incidence X-ray absorption spectroscopy (XAS) measurements were completed on oriented single crystals of magnesite [MgCO 3] and brucite [Mg(OH) 2] reacted with aqueous uranyl chloride above and below the solubility boundaries of schoepite (500, 50, and 5 ppm) at pH 8.3 and at ambient (P CO2 = 10 –3.5) or reduced partial pressures of carbon dioxide (P CO2 = 10 –4.5). X-ray absorption near edge structure (XANES) spectra show a striking polarization dependence (χ = 0° and 90° relative to the polarization plane of the incident beam) and consistently demonstrated that the uranyl molecule was preferentially oriented withmore » its O axial = U(VI) = O axial linkage at high angles (60–80°) to both magnesite (101¯4) and brucite (0001). Extended X-ray absorption fine structure (EXAFS) analysis shows that the “effective” number of U(VI) axial oxygens is the most strongly affected fitting parameter as a function of polarization. Furthermore, axial tilt in the surface thin films (thickness ~ 21 Å) is correlated with surface roughness [σ]. Our results show that hydrated uranyl(-carbonate) complexes polymerize on all of our experimental surfaces and that this process is controlled by surface hydroxylation. Lastly, these results provide new insights into the bonding configuration expected for uranyl complexes on the environmentally significant carbonate and hydroxide mineral surfaces.« less

Uranium Immobilization and Nanofilm Formation on Magnesium-Rich Minerals.

PubMed

van Veelen, Arjen; Bargar, John R; Law, Gareth T W; Brown, Gordon E; Wogelius, Roy A

2016-04-05

Polarization-dependent grazing incidence X-ray absorption spectroscopy (XAS) measurements were completed on oriented single crystals of magnesite [MgCO3] and brucite [Mg(OH)2] reacted with aqueous uranyl chloride above and below the solubility boundaries of schoepite (500, 50, and 5 ppm) at pH 8.3 and at ambient (PCO2 = 10(-3.5)) or reduced partial pressures of carbon dioxide (PCO2 = 10(-4.5)). X-ray absorption near edge structure (XANES) spectra show a striking polarization dependence (χ = 0° and 90° relative to the polarization plane of the incident beam) and consistently demonstrated that the uranyl molecule was preferentially oriented with its Oaxial═U(VI)═Oaxial linkage at high angles (60-80°) to both magnesite (101̅4) and brucite (0001). Extended X-ray absorption fine structure (EXAFS) analysis shows that the "effective" number of U(VI) axial oxygens is the most strongly affected fitting parameter as a function of polarization. Furthermore, axial tilt in the surface thin films (thickness ∼ 21 Å) is correlated with surface roughness [σ]. Our results show that hydrated uranyl(-carbonate) complexes polymerize on all of our experimental surfaces and that this process is controlled by surface hydroxylation. These results provide new insights into the bonding configuration expected for uranyl complexes on the environmentally significant carbonate and hydroxide mineral surfaces.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehta, Vrajesh; Maillot, Fabien; Wang, Zheming

Uranyl phosphate solids are often found with uranium ores, and their low solubility makes them promising target phases for in situ remediation of uranium-contaminated subsurface environments. The products and solubility of uranium(VI) precipitated with phosphate can be affected by the pH, dissolved inorganic carbon (DIC) concentration, and co-solute composition (e.g. Na+/Ca2+) of the groundwater. Batch experiments were performed to study the effect of these parameters on the products and extent of uranium precipitation induced by phosphate addition. In the absence of co-solute cations, chernikovite [H3O(UO2)(PO4)•3H2O] precipitated despite uranyl orthophosphate [(UO2)3(PO4)2•4H2O] being thermodynamically more favorable under certain conditions. As determined usingmore » X-ray diffraction, electron microscopy, and laser induced fluorescence spectroscopy, the presence of Na+ or Ca2+ as a co-solute led to the precipitation of sodium autunite ([Na2(UO2)2(PO4)2] and autunite [Ca(UO2)2(PO4)2]), which are structurally similar to chernikovite. In the presence of sodium, the dissolved U(VI) concentrations were generally in agreement with equilibrium predictions of sodium autunite solubility. However, in the calcium-containing systems, the observed concentrations were below the predicted solubility of autunite, suggesting the possibility of uranium adsorption to or incorporation in a calcium phosphate precipitate in addition to the precipitation of autunite.« less

ION EXCHANGE SUBSTANCES BY SAPONIFICATION OF ALLYL PHOSPHATE POLYMERS

DOEpatents

Kennedy, J.

1959-04-14

An ion exchange resin having a relatively high adsorption capacity tor uranyl ion as compared with many common cations is reported. The resin comprises an alphyl-allyl hydrogen phosphate polymer, the alphyl group being either allyl or a lower alkyl group having up to 5 carbon atoins. The resin is prepared by polymerizing compounds such as alkyl-diallyl phosphate and triallyl phosphate in the presence of a free radical generating substance and then partially hydrolyzing the resulting polymer to cause partial replacement of organic radicals by cations. A preferred free radical gencrating agent is dibenzoyl peroxide. The partial hydrolysis is brought about by refluxing the polymer with concentrated aqueous NaOH for three or four hours.

U-EXTRACTION--IMPROVEMENTS IN ELIMINATION OF Mo BY USE OF FERRIC ION

DOEpatents

Clark, H.M.; Duffey, D.

1958-06-10

An improved solvent extraction process is described whereby U may be extracted by a water immiscible organic solvent from an aqueous solution of uranyl nitrate. It has been found that Mo in the presence of phosphate ions appears to form a complex with the phosphate which extracts along with the U. This extraction of Mo may be suppressed by providing ferric ion in the solution prior to the extraction step. The ferric ion is preferably provided in the form of ferric nitrate.

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

NASA Astrophysics Data System (ADS)

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

2017-01-01

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

XAFS investigation of polyamidoxime-bound uranyl contests the paradigm from small molecule studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayes, Richard T.; Piechowicz, Marek; Lin, Zekai

In this study, limited resource availability and population growth have motivated interest in harvesting valuable metals from unconventional reserves, but developing selective adsorbents for this task requires structural knowledge of metal binding environments. Amidoxime polymers have been identified as the most promising platform for large-scale extraction of uranium from seawater. However, despite more than 30 years of research, the uranyl coordination environment on these adsorbents has not been positively identified. We report the first XAFS investigation of polyamidoxime-bound uranyl, with EXAFS fits suggesting a cooperative chelating model, rather than the tridentate or η 2 motifs proposed by small molecule andmore » computational studies. Samples exposed to environmental seawater also display a feature consistent with a μ 2-oxo-bridged transition metal in the uranyl coordination sphere, suggesting in situ formation of a specific binding site or mineralization of uranium on the polymer surface. These unexpected findings challenge several long-held assumptions and have significant implications for development of polymer adsorbents with high selectivity.« less

XAFS investigation of polyamidoxime-bound uranyl contests the paradigm from small molecule studies

DOE PAGES

Mayes, Richard T.; Piechowicz, Marek; Lin, Zekai; ...

2015-11-12

In this study, limited resource availability and population growth have motivated interest in harvesting valuable metals from unconventional reserves, but developing selective adsorbents for this task requires structural knowledge of metal binding environments. Amidoxime polymers have been identified as the most promising platform for large-scale extraction of uranium from seawater. However, despite more than 30 years of research, the uranyl coordination environment on these adsorbents has not been positively identified. We report the first XAFS investigation of polyamidoxime-bound uranyl, with EXAFS fits suggesting a cooperative chelating model, rather than the tridentate or η 2 motifs proposed by small molecule andmore » computational studies. Samples exposed to environmental seawater also display a feature consistent with a μ 2-oxo-bridged transition metal in the uranyl coordination sphere, suggesting in situ formation of a specific binding site or mineralization of uranium on the polymer surface. These unexpected findings challenge several long-held assumptions and have significant implications for development of polymer adsorbents with high selectivity.« less

Bio-precipitation of uranium by two bacterial isolates recovered from extreme environments as estimated by potentiometric titration, TEM and X-ray absorption spectroscopic analyses.

PubMed

Merroun, Mohamed L; Nedelkova, Marta; Ojeda, Jesus J; Reitz, Thomas; Fernández, Margarita López; Arias, José M; Romero-González, María; Selenska-Pobell, Sonja

2011-12-15

This work describes the mechanisms of uranium biomineralization at acidic conditions by Bacillus sphaericus JG-7B and Sphingomonas sp. S15-S1 both recovered from extreme environments. The U-bacterial interaction experiments were performed at low pH values (2.0-4.5) where the uranium aqueous speciation is dominated by highly mobile uranyl ions. X-ray absorption spectroscopy (XAS) showed that the cells of the studied strains precipitated uranium at pH 3.0 and 4.5 as a uranium phosphate mineral phase belonging to the meta-autunite group. Transmission electron microscopic (TEM) analyses showed strain-specific localization of the uranium precipitates. In the case of B. sphaericus JG-7B, the U(VI) precipitate was bound to the cell wall. Whereas for Sphingomonas sp. S15-S1, the U(VI) precipitates were observed both on the cell surface and intracellularly. The observed U(VI) biomineralization was associated with the activity of indigenous acid phosphatase detected at these pH values in the absence of an organic phosphate substrate. The biomineralization of uranium was not observed at pH 2.0, and U(VI) formed complexes with organophosphate ligands from the cells. This study increases the number of bacterial strains that have been demonstrated to precipitate uranium phosphates at acidic conditions via the activity of acid phosphatase. Copyright © 2011 Elsevier B.V. All rights reserved.

URANIUM RECOVERY PROCESS

DOEpatents

Hyman, H.H.; Dreher, J.L.

1959-07-01

The recovery of uranium from the acidic aqueous metal waste solutions resulting from the bismuth phosphate carrier precipitation of plutonium from solutions of neutron irradiated uranium is described. The waste solutions consist of phosphoric acid, sulfuric acid, and uranium as a uranyl salt, together with salts of the fission products normally associated with neutron irradiated uranium. Generally, the process of the invention involves the partial neutralization of the waste solution with sodium hydroxide, followed by conversion of the solution to a pH 11 by mixing therewith sufficient sodium carbonate. The resultant carbonate-complexed waste is contacted with a titanated silica gel and the adsorbent separated from the aqueous medium. The aqueous solution is then mixed with sufficient acetic acid to bring the pH of the aqueous medium to between 4 and 5, whereby sodium uranyl acetate is precipitated. The precipitate is dissolved in nitric acid and the resulting solution preferably provided with salting out agents. Uranyl nitrate is recovered from the solution by extraction with an ether such as diethyl ether.

Simultaneous reduction of arsenic(V) and uranium(VI) by mackinawite: role of uranyl arsenate precipitate formation.

PubMed

Troyer, Lyndsay D; Tang, Yuanzhi; Borch, Thomas

2014-12-16

Uranium (U) and arsenic (As) often occur together naturally and, as a result, can be co-contaminants at sites of uranium mining and processing, yet few studies have examined the simultaneous redox dynamics of U and As. This study examines the influence of arsenate (As(V)) on the reduction of uranyl (U(VI)) by the redox-active mineral mackinawite (FeS). As(V) was added to systems containing 47 or 470 μM U(VI) at concentrations ranging from 0 to 640 μM. In the absence of As(V), U was completely removed from solution and fully reduced to nano-uraninite (nano-UO2). While the addition of As(V) did not reduce U uptake, at As(V) concentrations above 320 μM, the reduction of U(VI) was limited due to the formation of a trögerite-like uranyl arsenate precipitate. The presence of U also significantly inhibited As(V) reduction. While less U(VI) reduction to nano-UO2 may take place in systems with high As(V) concentrations, formation of trögerite-like mineral phases may be an acceptable reclamation end point due to their high stability under oxic conditions.

SOLVENT EXTRACTION PROCESS

DOEpatents

Jonke, A.A.

1957-10-01

In improved solvent extraction process is described for the extraction of metal values from highly dilute aqueous solutions. The process comprises contacting an aqueous solution with an organic substantially water-immiscible solvent, whereby metal values are taken up by a solvent extract phase; scrubbing the solvent extract phase with an aqueous scrubbing solution; separating an aqueous solution from the scrubbed solvent extract phase; and contacting the scrubbed solvent phase with an aqueous medium whereby the extracted metal values are removed from the solvent phase and taken up by said medium to form a strip solution containing said metal values, the aqueous scrubbing solution being a mixture of strip solution and an aqueous solution which contains mineral acids anions and is free of the metal values. The process is particularly effective for purifying uranium, where one starts with impure aqueous uranyl nitrate, extracts with tributyl phosphate dissolved in carbon tetrachloride, scrubs with aqueous nitric acid and employs water to strip the uranium from the scrubbed organic phase.

Cellular distribution of uranium after acute exposure of renal epithelial cells: SEM, TEM and nuclear microscopy analysis

NASA Astrophysics Data System (ADS)

Carrière, Marie; Gouget, Barbara; Gallien, Jean-Paul; Avoscan, Laure; Gobin, Renée; Verbavatz, Jean-Marc; Khodja, Hicham

2005-04-01

The major health effect of uranium exposure has been reported to be chemical kidney toxicity, functional and histological damages being mainly observed in proximal tubule cells. Uranium enters the proximal tubule as uranyl-bicarbonate or uranyl-citrate complexes. The aim of our research is to investigate the mechanisms of uranium toxicity, intracellular accumulation and repartition after acute intoxication of rat renal proximal tubule epithelial cells, as a function of its chemical form. Microscopic observations of renal epithelial cells after acute exposure to uranyl-bicarbonate showing the presence of intracellular precipitates as thin needles of uranyl-phosphate localized in cell lysosomes have been published. However the initial site of precipitates formation has not been identified yet: they could either be formed outside the cells before internalization, or directly inside the cells. Uranium solubility as a function and initial concentration was specified by ICP-MS analysis of culture media. In parallel, uranium uptake and distribution in cell monolayers exposed to U-bicarbonate was investigated by nuclear microprobe analyses. Finally, the presence of uranium precipitates was tested out by scanning electron microscopic observations (SEM), while extracellular and/or intracellular precipitates were observed on thin sections of cells by transmission electron microscopy (TEM).

Molecular dynamics simulations of uranyl adsorption and structure on the basal surface of muscovite

DOE PAGES

Teich-McGoldrick, Stephanie L.; Greathouse, Jeffery A.; Cygan, Randall T.

2014-02-05

Anthropogenic activities have led to an increased concentration of uranium on the Earth’s surface and potentially in the subsurface with the development of nuclear waste repositories. Uranium is soluble in groundwater, and its mobility is strongly affected by the presence of clay minerals in soils and in subsurface sediments. We use molecular dynamics simulations to probe the adsorption of aqueous uranyl (UO 2 2+) ions onto the basal surface of muscovite, a suitable proxy for typically ultrafine-grained clay phases. Model systems include the competitive adsorption between potassium counterions and aqueous ions (0.1 M and 1.0 M UO 2Cl 2 ,more » 0.1 M NaCl). We find that for systems with potassium and uranyl ions present, potassium ions dominate the adsorption phenomenon. Potassium ions adsorb entirely as inner-sphere complexes associated with the ditrigonal cavity of the basal surface. Uranyl ions adsorb in two configurations when it is the only ion species present, and in a single configuration in the presence of potassium. Finally, the majority of adsorbed uranyl ions are tilted less than 45° relative to the muscovite surface, and are associated with the Si 4Al 2 rings near aluminum substitution sites.« less

Dehydration of the Uranyl Peroxide Studtite, [UO 2(η 2-O 2)(H 2O) 2]·2H 2O, Affords a Drastic Change in the Electronic Structure: A Combined X-ray Spectroscopic and Theoretical Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vitova, Tonya; Pidchenko, Ivan; Biswas, Saptarshi

The dehydration of studtite, [UO 2(2-O 2)(H 2O)2]·2H 2O, to metastudtite, [UO 2(2-O 2)(H 2O) 2], uranyl peroxide minerals that are major oxidative alteration phases of UO2 under conditions of geological storage, has been studied using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy. XPS of the U 4f region shows small but significant differences between studtite and metastudtite, with the 4f binding energy of studtite the highest reported for a uranyl mineral studied by this technique. Further information on the changes in the electronic structure was elucidated using U M4-edge High Energy Resolution XANES (HR-XANES) spectroscopy, which directly probesmore » f-orbital states. The transition from the 3d to the 5f* orbital is sensitive to variations of the U=Oaxial bond length and to changes in the bond covalency. We report evidences that the covalence in the uranyl fragment decreases upon dehydration. Photoluminescence spectroscopy at near liquid helium temperatures reveals significant spectral differences between the two materials, correlating with the X-ray spectroscopy results. A theoretical investigation has been conducted on the structures of both studtite and metastudtite and benchmarked to the HR-XANES spectra. These illustrate the sensitivity of the 3d to the 5f * transition towards U=Oaxial bond variation.« less

Phosphorus K-edge XANES spectroscopy of mineral standards

PubMed Central

Ingall, Ellery D.; Brandes, Jay A.; Diaz, Julia M.; de Jonge, Martin D.; Paterson, David; McNulty, Ian; Elliott, W. Crawford; Northrup, Paul

2011-01-01

Phosphorus K-edge X-ray absorption near-edge structure (XANES) spectroscopy was performed on phosphate mineral specimens including (a) twelve specimens from the apatite group covering a range of compositional variation and crystallinity; (b) six non-apatite calcium-rich phosphate minerals; (c) 15 aluminium-rich phosphate minerals; (d) ten phosphate minerals rich in either reduced iron or manganese; (e) four phosphate minerals rich in either oxidized iron or manganese; (f) eight phosphate minerals rich in either magnesium, copper, lead, zinc or rare-earth elements; and (g) four uranium phosphate minerals. The identity of all minerals examined in this study was independently confirmed using X-ray powder diffraction. Minerals were distinguished using XANES spectra with a combination of pre-edge features, edge position, peak shapes and post-edge features. Shared spectral features were observed in minerals with compositions dominated by the same specific cation. Analyses of apatite-group minerals indicate that XANES spectral patterns are not strongly affected by variations in composition and crystallinity typical of natural mineral specimens. PMID:21335905

Structural Phase Transitions and Water Dynamics in Uranyl Fluoride Hydrates

DOE PAGES

Miskowiec, Andrew J.; Kirkegaard, Marie C.; Huq, Ashfia; ...

2015-11-17

We report a novel production method for uranium oxy uoride [(UO 2) 7F 14(H 2O) 7] 4H 2O, referred to as structure D. Structure D is produced as a product of hydrating anhydrous uranyl uoride, UO 2F 2, through the gas phase at ambient temperatures fol- lowed by desiccation by equilibration with a dry environment. We follow the structure of [(UO 2) 7F 14(H 2O) 7] 4H 2O through an intermediate, liquid-like phase, wherein the coordination number of the uranyl ion is reduced to 5 (from 6 in the anhydrous struc- ture), and a water molecule binds as an equatorialmore » ligand to the uranyl ion. Quasielas- tic neutron scattering results compare well with previous measurements of mineral hydrates. The two groups of structurally distinct water molecules in D perform re- stricted motion on a length scale commensurate with the O{H bond (r = 0.92 A). The more tightly bound equatorial ligand waters rotate slower (Dr = 2.2 ps -1) than their hydrogen-bonded partners (Dr = 28.7 ps -1).« less

Molten salt flux synthesis and crystal structure of a new open-framework uranyl phosphate Cs{sub 3}(UO{sub 2}){sub 2}(PO{sub 4})O{sub 2}: Spectroscopic characterization and cationic mobility studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yagoubi, S., E-mail: said.yagoubi@cea.fr; Renard, C.; Abraham, F.

2013-04-15

The reaction of triuranyl diphosphate tetrahydrate precursor (UO{sub 2}){sub 3}(PO{sub 4}){sub 2}(H{sub 2}O){sub 4} with a CsI flux at 750 °C yields a yellow single crystals of new compound Cs{sub 3}(UO{sub 2}){sub 2}(PO{sub 4})O{sub 2}. The crystal structure (monoclinic, space group C2/c, a=13.6261 (13) Å, b=8.1081(8) Å, c=12.3983(12) Å, β=114.61(12)°, V=1245.41(20) Å{sup 3} with Z=4) has been solved using direct methods and Fourier difference techniques. A full-matrix least-squares refinement on the basis of F{sup 2} yielded R1=0.028 and wR2=0.071 for 79 parameters and 1352 independent reflections with I≥2σ(I) collected on a BRUKER AXS diffractometer with MoKα radiation and a charge-coupledmore » device detector. The crystal structure is built by two independent uranium atoms in square bipyramidal coordination, connected by two opposite corners to form infinite chains {sup 1}{sub ∞}[UO{sub 5}] and by one phosphorus atom in a tetrahedral environment PO{sub 4}. The two last entities {sup 1}{sub ∞}[UO{sub 5}] and PO{sub 4} are linked by sharing corners to form a three-dimensional structure presenting different types of channels occupied by Cs{sup +} alkaline cations. Their mobility within the tunnels were studied between 280 and 800 °C and compared with other tunneled uranyl minerals. The infrared spectrum shows a good agreement with the values inferred from the single crystal structure analysis of uranyl phosphate compound. - Graphical abstract: Arrhenius plot of the electrical conductivity of tunneled compounds Cs{sub 3}U{sub 2}PO{sub 10} and CsU{sub 2}Nb{sub 2}O{sub 11.5}. Highlights: ► The reaction of (UO{sub 2}){sub 3}(PO{sub 4}){sub 2}(H{sub 2}O){sub 4} in excess of molten CsI leads to single-crystals of new tunneled compound Cs{sub 3}(UO{sub 2}){sub 2}(PO{sub 4})O{sub 2}. ► Ionic conductivity measurements and crystal structure analysis indicate a strong connection of the Cs{sup +} cations to the tunnels. ► A low symmetry in Cs{sub 3}(UO{sub 2}){sub 2}(PO{sub 4})O{sub 2} is the cause of IR activation and splitting of the bands in the IR spectrum.« less

Structure, Kinetics, and Thermodynamics of the Aqueous Uranyl(VI) Cation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kerisit, Sebastien N.; Liu, Chongxuan

2013-08-20

Molecular simulation techniques are employed to gain insights into the structural, kinetic, and thermodynamic properties of the uranyl(VI) cation (UO22+) in aqueous solution. The simulations make use of an atomistic potential model (force field) derived in this work and based on the model of Guilbaud and Wipff (Guilbaud, P.; Wipff, G. J. Mol. Struct. (THEOCHEM) 1996, 366, 55-63). Reactive flux and thermodynamic integration calculations show that the derived potential model yields predictions for the water exchange rate and free energy of hydration, respectively, that are in agreement with experimental data. The water binding energies, hydration shell structure, and self-diffusion coefficientmore » are also calculated and discussed. Finally, a combination of metadynamics and transition path sampling simulations is employed to probe the mechanisms of water exchange reactions in the first hydration shell of the uranyl ion. These atomistic simulations indicate, based on two-dimensional free energy surfaces, that water exchanges follow an associative interchange mechanism. The nature and structure of the water exchange transition states are also determined. The improved potential model is expected to lead to more accurate predictions of uranyl adsorption energies at mineral surfaces using potential-based molecular dynamics simulations.« less

Fourier transform Raman spectroscopy of synthetic and biological calcium phosphates.

PubMed

Sauer, G R; Zunic, W B; Durig, J R; Wuthier, R E

1994-05-01

Fourier-transform (FT) Raman spectroscopy was used to characterize the organic and mineral components of biological and synthetic calcium phosphate minerals. Raman spectroscopy provides information on biological minerals that is complimentary to more widely used infrared methodologies as some infrared-inactive vibrational modes are Raman-active. The application of FT-Raman technology has, for the first time, enabled the problems of high sample fluorescence and low signal-to-noise that are inherent in calcified tissues to be overcome. Raman spectra of calcium phosphates are dominated by a very strong band near 960 cm-1 that arises from the symmetric stretching mode (v1) of the phosphate group. Other Raman-active phosphate vibrational bands are seen at approximately 1075 (v3), 590 (v4), and 435 cm-1 (v2). Minerals containing acidic phosphate groups show additional vibrational modes. The different calcium phosphate mineral phases can be distinguished from one another by the relative positions and shapes of these bands in the Raman spectra. FT-Raman spectra of nascent, nonmineralized matrix vesicles (MV) show a distinct absence of the phosphate v1 band even though these structures are rich in calcium and phosphate. Similar results were seen with milk casein and synthetic Ca-phosphatidyl-serine-PO4 complexes. Hence, the phosphate and/or acidic phosphate ions in these noncrystalline biological calcium phosphates is in a molecular environment that differs from that in synthetic amorphous calcium phosphate. In MV, the first distinct mineral phase to form contained acidic phosphate bands similar to those seen in octacalcium phosphate. The mineral phase present in fully mineralized MV was much more apatitic, resembling that found in bones and teeth.(ABSTRACT TRUNCATED AT 250 WORDS)

Mineral resource of the month: Phosphate rock

USGS Publications Warehouse

Jasinski, Stephen M.

2013-01-01

As a mineral resource, “phosphate rock” is defined as unprocessed ore and processed concentrates that contain some form of apatite, a group of calcium phosphate minerals that is the primary source for phosphorus in phosphate fertilizers, which are vital to agriculture.

XANES and EXAFS investigation of uranium incorporation on nZVI in the presence of phosphate.

PubMed

Qiu, Muqing; Wang, Min; Zhao, Qingzhou; Hu, Baowei; Zhu, Yuling

2018-06-01

Effect of phosphate on the reduction of U(VI) on nZVI was determined by batch, XPS, XANES and EXAFS techniques. The batch experiments showed that nZVI was quite effective for the removal of uranium under the anaerobic conditions, whereas the addition of phosphate enhanced uranium removal over wide pH range. At low pH, the reduction of U(VI) to U(IV) significantly decreased with increasing phosphate concentration by XPS and XANES analysis. According to EXAFS analysis, the occurrence of UU shell at 10 mg/L phosphate and pH 4.0 was similar to that of U (IV) O 2 (s), whereas the UP and UFe shells were observed at 50 mg/L phosphate, revealing that reductive co-precipitate (U (IV) O 2 (s)) and precipitation of uranyl-phosphate were observed at low and high phosphate, respectively. The findings are crucial for the prediction of the effect of phosphate on the speciation and binding of uranium by nZVI at low pH, which is significant in controlling the mobility of U(VI) in contaminated environments. Copyright © 2018 Elsevier Ltd. All rights reserved.

Accumulation of zirconium phosphate by a Serratia sp.: a benign system for the removal of radionuclides from aqueous flows.

PubMed

Mennan, Claire; Paterson-Beedle, Marion; Macaskie, Lynne E

2010-10-01

Metal phosphate deposited enzymatically on Serratia sp. has been used successfully for the removal of radionuclides from aqueous flows. Previous studies using biogenic hydrogen uranyl phosphate (HUP) on Serratia sp. biofilm showed removal of 100% of (90)Sr, (137)Cs, and (60)Co via their intercalation into biogenic HUP crystals. Zirconium phosphates (ZrP) offer a potential non-toxic and non-radioactive alternative to HUP for water decontamination. A method was developed for biomanufacturing ZrP. Biogenic ZrP removed ca. 100% of Sr(2+) and Co(2+) (0.5 mM) from solutions to a molar ratio at saturation of ca. 1:0.6 for both Zr:Sr and Zr:Co. The potential for drinking water decontamination via bio-ZrP is discussed with respect to bio-HUP and also other commercially available materials.

Molecular Simulations of the Diffusion of Uranyl Carbonate Species in Nanosized Mineral Fractures

NASA Astrophysics Data System (ADS)

Kerisit, S.; Liu, C.

2010-12-01

Uranium is a major groundwater contaminant at uranium processing and mining sites as a result of intentional and accidental discharges of uranium-containing waste products into subsurface environments. Recent characterization has shown that uranium preferentially associates with intragrain and intra-aggregate domains in some of the uranium-contaminated sediments collected from the US Department of Energy Hanford Site [1, 2]. In these sediments, uranium existed as precipitated and/or adsorbed phases in grain micropores with nano- to microscale sizes. Desorption and diffusion characterization studies and continuum-scale modeling indicated that ion diffusion in the microfractures is a major mechanism that led to preferential uranium concentration in the microfracture regions and will control the future mobility of uranium in the subsurface sediments [1, 3-4]. However, the diffusion properties of uranyl species in the intragrain regions, especially at the solid-liquid interface, are still poorly understood. Therefore, a general aim of this work is to provide atomic-level insights into the contribution of microscopic surface effects to the slow diffusion process of uranyl species in porous media with nano- to microsized fractures. In this presentation, we will first present molecular dynamics (MD) simulations of feldspar-water interfaces to investigate their interfacial structure and dynamics and establish a theoretical framework for subsequent simulations of water and ion diffusion at these interfaces [5]. We will then report on MD simulations carried out to probe the effects of confinement and of the presence of the mineral surface on the diffusion of water and electrolyte ions in nanosized feldspar fractures [6]. Several properties of the mineral-water interface were varied, such as the fracture width, the ionic strength of the contacting solution, and the surface charge. Our calculations reveal a 2.0-2.5 nm interfacial region within which the diffusion properties of water and that of the electrolyte ions differ significantly from those in bulk aqueous solutions. We will then present MD simulations of the diffusion of a series of alkaline-earth uranyl carbonate species in aqueous solutions [7]. The MD simulations show that the alkaline-earth uranyl carbonate complexes have distinct water exchange dynamics, which could lead to different reactivities. Finally, we will present recent results on the diffusion and adsorption of uranyl carbonate species in intragrain micropores, modeled with the feldspar-water interfaces mentioned in the above, to help interpret the diffusion behavior of uranium in contaminated sediments. [1] Liu C. et al. Geochim. Cosmochim. Acta 68 4519 (2004) [2] McKinley J. P. et al. Geochim. Cosmochim. Acta 70 1873 (2006) [3] Liu C. et al. Water Resour. Res. 42 W12420 (2006) [4] Ilton E. S. et al. Environ. Sci. Technol. 42 1565 (2009) [5] Kerisit S. et al. Geochim. Cosmochim. Acta 72 1481 (2008) [6] Kerisit S. and Liu C. Environ. Sci. Technol. 43 777 (2009) [7] Kerisit S. and Liu C. Geochim. Cosmochim. Acta 74 4937 (2010)

Laser induced phosphorescence uranium analysis

DOEpatents

Bushaw, B.A.

1983-06-10

A method is described for measuring the uranium content of aqueous solutions wherein a uranyl phosphate complex is irradiated with a 5 nanosecond pulse of 425 nanometer laser light and resultant 520 nanometer emissions are observed for a period of 50 to 400 microseconds after the pulse. Plotting the natural logarithm of emission intensity as a function of time yields an intercept value which is proportional to uranium concentration.

Laser induced phosphorescence uranium analysis

DOEpatents

Bushaw, Bruce A.

1986-01-01

A method is described for measuring the uranium content of aqueous solutions wherein a uranyl phosphate complex is irradiated with a 5 nanosecond pulse of 425 nanometer laser light and resultant 520 nanometer emissions are observed for a period of 50 to 400 microseconds after the pulse. Plotting the natural logarithm of emission intensity as a function of time yields an intercept value which is proportional to uranium concentration.

METHOD FOR DECONTAMINATION OF REACTOR SOLUTIONS

DOEpatents

Maraman, W.J.; Baxman, H.R.; Baker, R.D.

1959-05-01

A process for U recovery from phosphate fuel solutions is described. To fuel solution drawn from the reactor is added Fe(NO/sub 3/)/sub 3/ which destroys the U complex and forms ferric phosphate complex. The UO/sub 2/(NO/sub 3/)/sub 2/ formed is extracted into TBP-kerosene in a countercurrent column. The TBP contalning UO/sub 2/(NO/sub 3/)/sub 2/ is further purified by an aqueous Al(NO/ sub 3/)/sub 3/ scrub solution. The pregnant solution then goes to an H/sub 3/PO/ sub 4/ stripping and kerosene washing column. The H/sub 3/PO/sub 4/--uranyl phosphate solution is separated at the bottom and boiled to remove HNO/sub 3/ then diluted to fuel solution make-up strength. (T.R.H.)

Biosorption and Biomineralization of U(VI) by the Marine Bacterium Idiomarina loihiensis MAH1: Effect of Background Electrolyte and pH

PubMed Central

Morcillo, Fernando; González-Muñoz, María T.; Reitz, Thomas; Romero-González, María E.; Arias, José M.; Merroun, Mohamed L.

2014-01-01

The main goal of this study is to compare the effects of pH, uranium concentration, and background electrolyte (seawater and NaClO4 solution) on the speciation of uranium(VI) associated with the marine bacterium Idiomarina loihiensis MAH1. This was done at the molecular level using a multidisciplinary approach combining X-ray Absorption Spectroscopy (XAS), Time-Resolved Laser-Induced Fluorescence Spectroscopy (TRLFS), and High Resolution Transmission Electron Microscopy (HRTEM). We showed that the U(VI)/bacterium interaction mechanism is highly dependent upon pH but also the nature of the used background electrolyte played a role. At neutral conditions and a U concentration ranging from 5·10−4 to 10−5 M (environmentally relevant concentrations), XAS analysis revealed that uranyl phosphate mineral phases, structurally resembling meta-autunite [Ca(UO2)2(PO4)2 2–6H2O] are precipitated at the cell surfaces of the strain MAH1. The formation of this mineral phase is independent of the background solution but U(VI) luminescence lifetime analyses demonstrated that the U(VI) speciation in seawater samples is more intricate, i.e., different complexes were formed under natural conditions. At acidic conditions, pH 2, 3 and 4.3 ([U] = 5·10−4 M, background electrolyte  = 0.1 M NaClO4), the removal of U from solution was due to biosorption to Extracellular Polysaccharides (EPS) and cell wall components as evident from TEM analysis. The L III-edge XAS and TRLFS studies showed that the biosorption process observed is dependent of pH. The bacterial cell forms a complex with U through organic phosphate groups at pH 2 and via phosphate and carboxyl groups at pH 3 and 4.3, respectively. The differences in the complexes formed between uranium and bacteria on seawater compared to NaClO4 solution demonstrates that the actinide/microbe interactions are influenced by the three studied factors, i.e., the pH, the uranium concentration and the chemical composition of the solution. PMID:24618567

Uranyl-Peroxide Clusters Incorporating Iron Trimers and Bridging by Bisphosphonate- and Carboxylate-Containing Ligands.

PubMed

Qiu, Jie; Dong, Sining; Szymanowski, Jennifer E S; Dobrowolska, Malgorzata; Burns, Peter C

2017-04-03

A hybrid uranium-iron cage nanocluster, [(UO 2 ) 24 (FeOH) 24 (O 2 ) 24 (PO 4 ) 8 (CH(COO)(PO 3 ) 2 ) 24 ] 96- (U 24 Fe 24 ), was synthesized using bridging ligands containing bisphosphonate and carboxylate groups. U 24 Fe 24 contains six tetramers of uranyl hexagonal bipyramids and eight iron trimers, each of which consists of three corner-sharing Fe 3+ octahedra and is stabilized by in situ formed phosphate and 2,2-bis(phosphonato)acetate (C 2 P 2 ) groups. Tetramers and trimers are bridged by 24 C 2 P 2 groups into a cage cluster. Crystals of U 24 Fe 24 present a paramagnetic-like behavior. X-ray scattering showed that U 24 Fe 24 forms in the reactant solution prior to crystallization and is stable upon dissolution in water.

Rates and mechanisms of uranyl oxyhydroxide mineral dissolution

NASA Astrophysics Data System (ADS)

Reinoso-Maset, Estela; Steefel, Carl I.; Um, Wooyong; Chorover, Jon; O'Day, Peggy A.

2017-06-01

Uranyl oxyhydroxide minerals are important weathering products in uranium-contaminated surface and subsurface environments that regulate dissolved uranium (U) concentrations. However, dissolution rates for this class of minerals and associated dissolution mechanisms have not been previously reported for circumneutral pH conditions, particularly for the case of flow through porous media. In this work, the dissolution rates of K- and Na-compreignacite (K2(UO2)6O4(OH)6·8H2O and Na2(UO2)6O4(OH)6·8H2O, respectively) were measured using flow-through columns reacted with two simulated background porewater (BPW) solutions of low and high dissolved carbonate concentration (ca. 0.2 and 2.8 mmol L-1). Column materials were characterized before and after reaction with electron microscopy, bulk chemistry, and EXAFS to identify structural and chemical changes during dissolution and to obtain insight into molecular-scale processes. The reactive transport code CrunchFlow was used to calculate overall dissolution rates while accounting for fluid transport and changes in mineral volume and reactive surface area, and results were compared to steady-state dissolution rate calculations. In low carbonate BPW systems, interlayer K and Na were initially leached from both minerals, and in Na-compreignacite, K and minor divalent cations from the input solution were incorporated into the mineral structure. Results of characterization analyses suggested that after reaction both K- and Na-compreignacite resembled a disordered K-compreignacite with altered surfaces. A 10-fold increase in dissolved carbonate concentration and corresponding increase in pH (from 6.65 to 8.40) resulted in a net removal of 58-87% of total U mass from the columns, compared to <1% net loss in low carbonate BPW systems. Steady-state release of dissolved U was not observed with high carbonate solutions and post-reaction characterizations indicated a lack of development of leached or altered surfaces. Dissolution rates (normalized to specific surface area) were 2.5-3 orders-of-magnitude faster in high versus low carbonate BPW systems, with Na-compreignacite dissolving more rapidly than K-compreignacite under both BPW conditions, possibly due to greater ion exchange (1.57 · 10-10 vs. 1.28 · 10-13 mol m-2 s-1 [log R = -9.81 and -12.89] and 5.79 · 10-10 vs. 3.71 · 10-13 mol m-2 s-1 [log R = -9.24 and -12.43] for K- and Na-compreignacite, respectively). Experimental and spectroscopic results suggest that the dissolution rate is controlled by bond breaking of a uranyl group and detachment from polyhedral layers of the mineral structure. With higher dissolved carbonate concentrations, this rate-determining step is accelerated by the formation of Ca-uranyl carbonate complexes (dominant species under these conditions), which resulted in an increase of the dissolution rates. Optimization of both dissolution rate and mineral volume fraction in the reactive transport model to account for U mass removal during dissolution more accurately reproduced effluent data in high carbonate systems, and resulted in faster overall rates compared with a steady-state dissolution assumption. This study highlights the importance of coupling reaction and transport processes during the quantification of mineral dissolution rates to accurately predict the fate of contaminants such as U in porous geomedia.

Rates and mechanisms of uranyl oxyhydroxide mineral dissolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reinoso-Maset, Estela; Steefel, Carl I.; Um, Wooyong

Uranyl oxyhydroxide minerals are important weathering products in uranium-contaminated surface and subsurface environments that regulate dissolved uranium concentrations. However, dissolution rates for this class of minerals and associated dissolution mechanisms have not been previously reported for circumneutral pH conditions, particularly for the case of flow through porous media. In this paper, the dissolution rates of K- and Na-compreignacite (K 2(UO 2) 6O 4(OH) 6·8H 2O and Na 2(UO 2) 6O 4(OH) 6·8H 2O respectively) were measured using flow-through columns reacted with two simulated background porewater (BPW) solutions of low and high dissolved total carbonate content (ca. 0.2 and 2.8 mmolmore » L -1). Column materials were characterized before and after reaction with electron microscopy, bulk chemistry, and EXAFS to identify structural and chemical changes during dissolution and to obtain insight into molecular-scale processes. The reactive transport code CrunchFlow was used to calculate overall dissolution rates while accounting for fluid transport and changes in mineral volume and reactive surface area and results were compared to steady-state dissolution rate calculations. In low carbonate BPW systems, interlayer K and Na were initially leached from both minerals, and in Na-compreignacite, K and minor divalent cations from the input solution were incorporated into the mineral structure. Results of characterization analyses suggested that after reaction both K- and Na-compreignacite resembled a disordered K-compreignacite with altered surfaces. A 10-fold increase in dissolved carbonate concentration and corresponding increase in pH (from 6.65 to 8.40) resulted in a net removal of 58-87% of total uranium mass from the columns, compared to <1% net loss in low carbonate BPW systems. Steady-state release of dissolved uranium was not observed with high carbonate solutions and post-reaction characterizations indicated a lack of development of leached or altered surfaces. Dissolution rates (normalized to specific surface area) were about 2.5-3 orders-of-magnitude faster in high versus low carbonate BPW systems, with Na-compreignacite dissolving more rapidly than K-compreignacite under both BPW conditions, possibly due to greater ion exchange (1.57·10 -10 vs. 1.28·10 -13 mol m -2 s -1 [log R = -9.81 and -12.89] and 5.79·10 -10 vs. 3.71·10 -13 mol m -2 s -1 [log R = -9.24 and -12.43] for K- and Na-compreignacite respectively). Experimental and spectroscopic results suggest that the dissolution rate is controlled by bond breaking of a uranyl group and detachment from polyhedral layers of the mineral structure. With higher dissolved carbonate concentrations, this rate-determining step is accelerated by the formation of Ca-uranyl carbonate complexes (dominant species under these conditions), which resulted in an increase of the dissolution rates. Optimization of both dissolution rate and mineral volume fraction in the reactive transport model to account for uranium mass removal during dissolution more accurately reproduced effluent data in high carbonate systems, and resulted in faster overall rates compared with a steady-state dissolution assumption. Finally, this study highlights the importance of coupling reaction and transport processes during the quantification of mineral dissolution rates to accurately predict the fate of contaminants such as uranium in porous geomedia.« less

Rates and mechanisms of uranyl oxyhydroxide mineral dissolution

DOE PAGES

Reinoso-Maset, Estela; Steefel, Carl I.; Um, Wooyong; ...

2017-06-01

Uranyl oxyhydroxide minerals are important weathering products in uranium-contaminated surface and subsurface environments that regulate dissolved uranium concentrations. However, dissolution rates for this class of minerals and associated dissolution mechanisms have not been previously reported for circumneutral pH conditions, particularly for the case of flow through porous media. In this paper, the dissolution rates of K- and Na-compreignacite (K 2(UO 2) 6O 4(OH) 6·8H 2O and Na 2(UO 2) 6O 4(OH) 6·8H 2O respectively) were measured using flow-through columns reacted with two simulated background porewater (BPW) solutions of low and high dissolved total carbonate content (ca. 0.2 and 2.8 mmolmore » L -1). Column materials were characterized before and after reaction with electron microscopy, bulk chemistry, and EXAFS to identify structural and chemical changes during dissolution and to obtain insight into molecular-scale processes. The reactive transport code CrunchFlow was used to calculate overall dissolution rates while accounting for fluid transport and changes in mineral volume and reactive surface area and results were compared to steady-state dissolution rate calculations. In low carbonate BPW systems, interlayer K and Na were initially leached from both minerals, and in Na-compreignacite, K and minor divalent cations from the input solution were incorporated into the mineral structure. Results of characterization analyses suggested that after reaction both K- and Na-compreignacite resembled a disordered K-compreignacite with altered surfaces. A 10-fold increase in dissolved carbonate concentration and corresponding increase in pH (from 6.65 to 8.40) resulted in a net removal of 58-87% of total uranium mass from the columns, compared to <1% net loss in low carbonate BPW systems. Steady-state release of dissolved uranium was not observed with high carbonate solutions and post-reaction characterizations indicated a lack of development of leached or altered surfaces. Dissolution rates (normalized to specific surface area) were about 2.5-3 orders-of-magnitude faster in high versus low carbonate BPW systems, with Na-compreignacite dissolving more rapidly than K-compreignacite under both BPW conditions, possibly due to greater ion exchange (1.57·10 -10 vs. 1.28·10 -13 mol m -2 s -1 [log R = -9.81 and -12.89] and 5.79·10 -10 vs. 3.71·10 -13 mol m -2 s -1 [log R = -9.24 and -12.43] for K- and Na-compreignacite respectively). Experimental and spectroscopic results suggest that the dissolution rate is controlled by bond breaking of a uranyl group and detachment from polyhedral layers of the mineral structure. With higher dissolved carbonate concentrations, this rate-determining step is accelerated by the formation of Ca-uranyl carbonate complexes (dominant species under these conditions), which resulted in an increase of the dissolution rates. Optimization of both dissolution rate and mineral volume fraction in the reactive transport model to account for uranium mass removal during dissolution more accurately reproduced effluent data in high carbonate systems, and resulted in faster overall rates compared with a steady-state dissolution assumption. Finally, this study highlights the importance of coupling reaction and transport processes during the quantification of mineral dissolution rates to accurately predict the fate of contaminants such as uranium in porous geomedia.« less

Uranium: A Dentist's perspective

PubMed Central

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

2012-01-01

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

Dissolution Rates and Mineral Lifetimes of Phosphate Containing Minerals and Implications for Mars

NASA Astrophysics Data System (ADS)

Adcock, C. T.; Hausrath, E.

2011-12-01

The objectives of NASA's Mars Exploration Program include exploring the planet's habitability and the possibility of past, present, or future life. This includes investigating "possible supplies of bioessential elements" [1]. Phosphate is one such bioessential element for life as we understand it. Phosphate is also abundant on Mars [2], and the phosphate rich minerals chlorapatite, fluorapatite, and merrillite have been observed in Martian meteorites [3]. Surface rock analyses from the MER Spirit also show the loss of a phosphate rich mineral from the rocks Wishstone and Watchtower at Gusev Crater [4,5], implying mineral dissolution. Dissolution rates of phosphate containing minerals are therefore important for characterizing phosphate mobility and bioavailability on Mars. Previous studies have measured dissolution rates of fluorapatite [6-8]. However, chlorapatite and merrillite (a non-terrestrial mineral similar to whitlockite) are more common phosphate minerals found in Martian meteorites [3], and few dissolution data exist for these minerals. We have begun batch dissolution experiments on chlorapatite, synthesized using methods of [9], and whitlockite, synthesized using a method modified from [10]. Additionally, we are dissolving Durango fluorapatite to compare to dissolution rates in literature, and natural Palermo whitlockite to compare to dissolution rates of our synthesized whitlockite. Batch dissolution experiments were performed after [8], using a 0.01 molar KNO3 solution with 0.1500g-0.3000g mineral powders and starting solution volumes of 180ml in LDPE reaction vessels. HNO3 or KOH were used to adjust initial pH as required. Dissolution rates are calculated from the rate of change of elemental concentration in solution as a function of time, and normalized to the mineral surface area as measured by BET. Resulting rates will be used to calculate mineral lifetimes for the different phosphate minerals under potential Mars-like aqueous conditions, and in future reactive transport modeling.

Calcium phosphate mineralization is widely applied in crustacean mandibles.

PubMed

Bentov, Shmuel; Aflalo, Eliahu D; Tynyakov, Jenny; Glazer, Lilah; Sagi, Amir

2016-02-24

Crustaceans, like most mineralized invertebrates, adopted calcium carbonate mineralization for bulk skeleton reinforcement. Here, we show that a major part of the crustacean class Malacostraca (which includes lobsters, crayfishes, prawns and shrimps) shifted toward the formation of calcium phosphate as the main mineral at specified locations of the mandibular teeth. In these structures, calcium phosphate is not merely co-precipitated with the bulk calcium carbonate but rather creates specialized structures in which a layer of calcium phosphate, frequently in the form of crystalline fluorapatite, is mounted over a calcareous "jaw". From a functional perspective, the co-existence of carbonate and phosphate mineralization demonstrates a biomineralization system that provides a versatile route to control the physico-chemical properties of skeletal elements. This system enables the deposition of amorphous calcium carbonate, amorphous calcium phosphate, calcite and apatite at various skeletal locations, as well as combinations of these minerals, to form graded composites materials. This study demonstrates the widespread occurrence of the dual mineralization strategy in the Malacostraca, suggesting that in terms of evolution, this feature of phosphatic teeth did not evolve independently in the different groups but rather represents an early common trait.

Calcium phosphate mineralization is widely applied in crustacean mandibles

PubMed Central

Bentov, Shmuel; Aflalo, Eliahu D.; Tynyakov, Jenny; Glazer, Lilah; Sagi, Amir

2016-01-01

Crustaceans, like most mineralized invertebrates, adopted calcium carbonate mineralization for bulk skeleton reinforcement. Here, we show that a major part of the crustacean class Malacostraca (which includes lobsters, crayfishes, prawns and shrimps) shifted toward the formation of calcium phosphate as the main mineral at specified locations of the mandibular teeth. In these structures, calcium phosphate is not merely co-precipitated with the bulk calcium carbonate but rather creates specialized structures in which a layer of calcium phosphate, frequently in the form of crystalline fluorapatite, is mounted over a calcareous “jaw”. From a functional perspective, the co-existence of carbonate and phosphate mineralization demonstrates a biomineralization system that provides a versatile route to control the physico-chemical properties of skeletal elements. This system enables the deposition of amorphous calcium carbonate, amorphous calcium phosphate, calcite and apatite at various skeletal locations, as well as combinations of these minerals, to form graded composites materials. This study demonstrates the widespread occurrence of the dual mineralization strategy in the Malacostraca, suggesting that in terms of evolution, this feature of phosphatic teeth did not evolve independently in the different groups but rather represents an early common trait. PMID:26906263

Mineral induced formation of sugar phosphates

NASA Technical Reports Server (NTRS)

Pitsch, S.; Eschenmoser, A.; Gedulin, B.; Hui, S.; Arrhenius, G.

1995-01-01

Glycolaldehyde phosphate, sorbed from highly dilute, weakly alkaline solution into the interlayer of common expanding sheet structure metal hydroxide minerals, condenses extensively to racemic aldotetrose-2, 4-diphophates, and aldohexose-2, 4, 6-triphosphates. The reaction proceeds mainly through racemic erythrose-2, 4-phosphate, and terminates with a large fraction of racemic altrose-2, 4, 6-phosphate. In the absence of an inductive mineral phase, no detectable homogeneous reaction takes place in the concentration- and pH range used. The reactant glycolaldehyde phosphate is practically completely sorbed within an hour from solutions with concentrations as low as 50 micron; the half-time for conversion to hexose phosphates is of the order of two days at room temperature and pH 9.5. Total production of sugar phosphates in the mineral interlayer is largely independent of the glycolaldehyde phosphate concentration in the external solution, but is determined by the total amount of GAP offered for sorption up to the capacity of the mineral. In the presence of equimolar amounts of rac-glyceraldehyde-2-phosphate, but under otherwise similar conditions, aldopentose-2, 4, -diphosphates also form, but only as a small fraction of the hexose-2, 4, 6-phosphates.

Summary of the mineralogy of the Colorado Plateau uranium ores

USGS Publications Warehouse

Weeks, Alice D.; Coleman, Robert Griffin; Thompson, Mary E.

1956-01-01

In the Colorado Plateau uranium has been produced chiefly from very shallow mines in carnotite ores (oxidized vanadiferous uranium ores) until recent deeper mining penetrated black unoxidized ores in water-saturated rocks and extensive exploration has discovered many deposits of low to nonvanadiferous ores. The uranium ores include a wide range from highly vanadiferous and from as much as one percent to a trace of copper, and contain a small amount of iron and traces of lead, zinc, molybdenum, cobalt, nickel, silver, manganese, and other metals. Recent investigation indicates that the carnotite ores have been derived by progressive oxidation of primary (unoxidized) black ores that contain low-valent uranium and vanadium oxides and silicates. The uranium minerals, uraninite and coffinite, are associated with coalified wood or other carbonaceous material. The vanadium minerals, chiefly montroseite, roscoelite, and other vanadium silicates, occur in the interstices of the sandstone and in siltstone and clay pellets as well as associated with fossil wood. Calcite, dolomite, barite and minor amounts of sulfides, arsenides, and selenides occur in the unoxidized ore. Partially oxidized vanadiferous ore is blue black, purplish brown, or greenish black in contrast to the black or dark gray unoxidized ore. Vanadium combines with uranium to form rauvite. The excess vanadium is present in corvusite, fernandinite, melanovanadite and many other quadrivalent and quinquevalent vanadium minerals as well as in vanadium silicates. Pyrite and part or all of the calcite are replaced by iron oxides and gypsum. In oxidized vanadiferous uranium ores the uranium is fixed in the relatively insoluble minerals carnotite and tyuyamunite, and the excess vanadium commonly combines with one or more of the following: calcium, sodium, potassium, magnesium, aluminum, iron, copper, manganese, or barium, or rarely it forms the hydrated pentoxide. The relatively stable vanadium silicates are little affected by oxidation. The unoxidized nonvanadiferous ores contain uraninite and coffinite in close association with coalified wood and iron and copper sulfides, and traces of many other sulfides, arsenides and selenides. The oxidized nonvanadiferous ores differ from the vanadiferous ores because, in the absence of vanadium to complex the uranium, a great variety of secondary yellow and greenish-yellow uranyl minerals are formed. The uranyl sulfates and carbonates are more common than the oxides, phosphates, arsenates, and silicates. Because the sulfates and carbonates are much less stable that carnotite, the oxidized nonvanadiferous ores occure only as halos around cores of unoxidized ore and do not form large oxidized deposits close to the surface of the ground as carnotite ores. Oxidation has taken place since the lowering of the water table in the present erosion cycle. Because of local structures and the highly lenticular character of the fluviatile host rocks perched water tables and water-saturated lenses of sandstone are common high above the regional water table. Unoxidized ore has been preserved in these water-saturated rocks and the boundary between oxidized and unoxidized ore is very irregular.

DOE Office of Scientific and Technical Information (OSTI.GOV)

van Veelen, Arjen; Bargar, John R.; Law, Gareth T. W.

Polarization-dependent grazing incidence X-ray absorption spectroscopy (XAS) measurements were completed on oriented single crystals of magnesite [MgCO 3] and brucite [Mg(OH) 2] reacted with aqueous uranyl chloride above and below the solubility boundaries of schoepite (500, 50, and 5 ppm) at pH 8.3 and at ambient (P CO2 = 10 –3.5) or reduced partial pressures of carbon dioxide (P CO2 = 10 –4.5). X-ray absorption near edge structure (XANES) spectra show a striking polarization dependence (χ = 0° and 90° relative to the polarization plane of the incident beam) and consistently demonstrated that the uranyl molecule was preferentially oriented withmore » its O axial = U(VI) = O axial linkage at high angles (60–80°) to both magnesite (101¯4) and brucite (0001). Extended X-ray absorption fine structure (EXAFS) analysis shows that the “effective” number of U(VI) axial oxygens is the most strongly affected fitting parameter as a function of polarization. Furthermore, axial tilt in the surface thin films (thickness ~ 21 Å) is correlated with surface roughness [σ]. Our results show that hydrated uranyl(-carbonate) complexes polymerize on all of our experimental surfaces and that this process is controlled by surface hydroxylation. Lastly, these results provide new insights into the bonding configuration expected for uranyl complexes on the environmentally significant carbonate and hydroxide mineral surfaces.« less

A Raman spectroscopic study of the uranyl sulphate mineral johannite.

PubMed

Frost, Ray L; Erickson, Kristy L; Cejka, Jirí; Reddy, B Jagannadha

2005-09-01

Raman spectroscopy at 298 and 77K has been used to study the secondary uranyl mineral johannite of formula (Cu(UO2)2(SO4)2(OH)2 x 8H2O). Four Raman bands are observed at 3593, 3523, 3387 and 3234cm(-1) and four infrared bands at 3589, 3518, 3389 and 3205cm(-1). The first two bands are assigned to OH- units (hydroxyls) and the second two bands to water units. Estimations of the hydrogen bond distances for these four bands are 3.35, 2.92, 2.79 and 2.70 A. A sharp intense band at 1042 cm(-1) is attributed to the (SO4)2- symmetric stretching vibration and the three Raman bands at 1147, 1100 and 1090cm(-1) to the (SO4)2- anti-symmetric stretching vibrations. The nu2 bending modes were at 469, 425 and 388 cm(-1) at 77K confirming the reduction in symmetry of the (SO4)2- units. At 77K two bands at 811 and 786 cm(-1) are attributed to the nu1 symmetric stretching modes of the (UO2)2+ units suggesting the non-equivalence of the UO bonds in the (UO2)2+ units. The band at 786cm(-1), however, may be related to water molecules libration modes. In the 77K Raman spectrum, bands are observed at 306, 282, 231 and 210cm(-1) with other low intensity bands found at 191, 170 and 149cm(-1). The two bands at 282 and 210 cm(-1) are attributed to the doubly degenerate nu2 bending vibration of the (UO2)2+ units. Raman spectroscopy can contribute significant knowledge in the study of uranyl minerals because of better band separation with significantly narrower bands, avoiding the complex spectral profiles as observed with infrared spectroscopy.

Assessment of calcium addition on the removal of U(VI) in the alkaline conditions created by NH 3 gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katsenovich, Yelena; Cardona, Claudia; Szecsody, Jim

Remediation of uranium (U) contamination in the deep vadose zone (VZ) sediments abundant in calcite mineral is a challenging task considering the formation of highly stable and mobile uranyl complexes with carbonate and calcium in pore water composition. There is a concern that uranium contamination in the VZ can serve as a continued source for groundwater pollution, creating a risk to human health and the environment through the groundwater pathway. This requires in-situ remediation of the radionuclide-contaminated VZ to convert soluble U species to low solubility precipitates that are stable in the natural environment. Injection of reactive gasses (e.g., NHmore » 3) is a promising technology to decrease U mobility in the unsaturated zone without the addition of liquid amendments. The NH 3 injection creates alkaline conditions that can alter the sediment pore water composition due to a release of elements from minerals (via desorption and dissolution) that are present in the sediment. However, it is not known how VZ pore water constituents (Si, Al 3+, HCO 3 -, and Ca 2 +) would affect U(VI) removal/precipitation in alkaline conditions. This study quantified the role of major pore water constituents typically present in the arid and semi-arid environments of the western regions of the U.S and identified solid uranium-bearing phases that could potentially precipitate from solutions approximating pore water compositions after pH manipulations via ammonia gas injections. Triplicate samples were prepared using six Si (5, 50 100, 150, 200, and 250 mM), six HCO 3 - (0, 3, 25, 50, 75, and 100 mM), and two Ca 2+ (5 and 10 mM) concentrations. The concentration of aluminum and uranium was kept constant at 5 mM and 0.0084 mM, respectively, in all synthetic formulations tested. Results showed that the percentage of U(VI) removal was controlled by the Si/Al molar ratios and Ca 2+ concentrations. Regardless of the bicarbonate concentration tested, the percentage of U(VI) removed increased as the Si/Al ratios were increased. However, higher Ca concentrations correlated with higher U(VI) removal, ranging between 96% and 99%, at low Si/Al ratios. The SEM images of dried precipitates displayed dense amorphous regions high in silica content, where EDS elemental analysis unveiled higher U atomic percentages. The formation of uranyl silicate and carbonate minerals was also predicted by the speciation modeling. XRD analysis revealed the presence of uranyl carbonate mineral phases (andersonite, grimselite); however, uranyl silicates predicted (Na-boltwoodite) were not identified experimentally, possibly due to the amorphous nature of the silica solid phases observed in our experiments.« less

Assessment of calcium addition on the removal of U(VI) in the alkaline conditions created by NH 3 gas

DOE PAGES

Katsenovich, Yelena; Cardona, Claudia; Szecsody, Jim; ...

2018-03-06

Remediation of uranium (U) contamination in the deep vadose zone (VZ) sediments abundant in calcite mineral is a challenging task considering the formation of highly stable and mobile uranyl complexes with carbonate and calcium in pore water composition. There is a concern that uranium contamination in the VZ can serve as a continued source for groundwater pollution, creating a risk to human health and the environment through the groundwater pathway. This requires in-situ remediation of the radionuclide-contaminated VZ to convert soluble U species to low solubility precipitates that are stable in the natural environment. Injection of reactive gasses (e.g., NHmore » 3) is a promising technology to decrease U mobility in the unsaturated zone without the addition of liquid amendments. The NH 3 injection creates alkaline conditions that can alter the sediment pore water composition due to a release of elements from minerals (via desorption and dissolution) that are present in the sediment. However, it is not known how VZ pore water constituents (Si, Al 3+, HCO 3 -, and Ca 2 +) would affect U(VI) removal/precipitation in alkaline conditions. This study quantified the role of major pore water constituents typically present in the arid and semi-arid environments of the western regions of the U.S and identified solid uranium-bearing phases that could potentially precipitate from solutions approximating pore water compositions after pH manipulations via ammonia gas injections. Triplicate samples were prepared using six Si (5, 50 100, 150, 200, and 250 mM), six HCO 3 - (0, 3, 25, 50, 75, and 100 mM), and two Ca 2+ (5 and 10 mM) concentrations. The concentration of aluminum and uranium was kept constant at 5 mM and 0.0084 mM, respectively, in all synthetic formulations tested. Results showed that the percentage of U(VI) removal was controlled by the Si/Al molar ratios and Ca 2+ concentrations. Regardless of the bicarbonate concentration tested, the percentage of U(VI) removed increased as the Si/Al ratios were increased. However, higher Ca concentrations correlated with higher U(VI) removal, ranging between 96% and 99%, at low Si/Al ratios. The SEM images of dried precipitates displayed dense amorphous regions high in silica content, where EDS elemental analysis unveiled higher U atomic percentages. The formation of uranyl silicate and carbonate minerals was also predicted by the speciation modeling. XRD analysis revealed the presence of uranyl carbonate mineral phases (andersonite, grimselite); however, uranyl silicates predicted (Na-boltwoodite) were not identified experimentally, possibly due to the amorphous nature of the silica solid phases observed in our experiments.« less

Phosphate toxicity and vascular mineralization.

PubMed

Razzaque, Mohammed S

2013-01-01

Vascular calcification or mineralization is a major complication seen in patients with advanced stages of chronic kidney disease (CKD), and it is associated with markedly increased morbidity and mortality. Most of the CKD-related vascular mineralization is attributable to abnormal mineral ion metabolism. Elevated serum calcium and phosphate levels, along with increased calcium-phosphorus byproduct, and the use of active vitamin D metabolites are thought to be the predisposing factors for developing vascular mineralization in patients with CKD. Recent experimental studies have shown that vascular mineralization can be suppressed by reducing serum phosphate levels, even in the presence of extremely high serum calcium and 1,25-dihydroxyvitamin D levels, indicating that reducing 'phosphate toxicity' should be the important therapeutic priority in CKD patients for minimizing the risk of developing vascular mineralization and the disease progression. Copyright © 2013 S. Karger AG, Basel.

On the mineral characteristics and geochemistry of the Florida phosphate of Four Corners and Hardee County mines

NASA Astrophysics Data System (ADS)

Baghdady, Ashraf R.; Howari, Fares M.; Al-Wakeel, Mohamed I.

2016-08-01

The Florida phosphate deposits in Four Corners and Hardee County mines are composed mainly of phosphate minerals and quartz in addition to subordinate proportions of feldspars, dolomite, calcite, gypsum, kaolinite, attapulgite and montmorillonite. These phosphorites contain three structurally different types of mudclasts: massive mudclasts, mudclasts with concentric structure and mudclasts consisting of agglomerates of apatite microparticles. The latter are represented by particles resembling phosphatized fossil bacteria associated with microbial filaments, and hollow apatite particles having surfacial coatings and connected to microbial filaments. The Florida phosphate particles are reworked and vary in mineral composition, color and shape. They are composed of a mixture of well-crystalline species including carbonate fluorapatite (francolite), carbonate apatite and fluorapatite. The color variation of the phosphate particles is related to difference in mineral composition, extent of diagenetic effects and reworking. The light-colored mudclasts are characterized by the presence of carbonate apatite and aluminum hydroxide phosphate minerals, whereas the dark mudclasts are rich in iron aluminum hydroxide phosphate minerals. The Florida phosphorites are suggested to be formed partially by authigenetic precipitation, replacement of the sea floor carbonate and diatomite, and microbial processes. With respect to elemental geochemistry, the analyzed particles contain small percentages of sulfur and iron which are related to the occurrence of pyrite. Traces of silica and alumina are recorded which may be attributed to the diagenetic. Some of the tested particles are relatively rich in phosphorous, fluorine, calcium, and magnesium, while poor in silicon, potassium and sulfur. Whereas, the bioclasts (especially teeth) are relatively rich in calcium, phosphorous and fluorine while poor in silicon, aluminum, magnesium and potassium. Hence, the microchemical analyses revealed that differential diagenesis affected mudclasts more than bioclasts. There is a complete compositional gradation between clay and phosphate particles which reflects their interaction. This involved kaolinitization of the phosphate particles, phosphatization of the clay mineral particles and production of silica.

Selective flotation of phosphate minerals with hydroxamate collectors

DOEpatents

Miller, Jan D.; Wang, Xuming; Li, Minhua

2002-01-01

A method is disclosed for separating phosphate minerals from a mineral mixture, particularly from high-dolomite containing phosphate ores. The method involves conditioning the mineral mixture by contacting in an aqueous in environment with a collector in an amount sufficient for promoting flotation of phosphate minerals. The collector is a hydroxamate compound of the formula; ##STR1## wherein R is generally hydrophobic and chosen such that the collector has solubility or dispersion properties it can be distributed in the mineral mixture, typically an alkyl, aryl, or alkylaryl group having 6 to 18 carbon atoms. M is a cation, typically hydrogen, an alkali metal or an alkaline earth metal. Preferably, the collector also comprises an alcohol of the formula, R'--OH wherein R' is generally hydrophobic and chosen such that the collector has solubility or dispersion properties so that it can be distributed in the mineral mixture, typically an alkyl, aryl, or alkylaryl group having 6 to 18 carbon atoms.

Separation of uranium from technetium in recovery of spent nuclear fuel

NASA Astrophysics Data System (ADS)

Friedman, H. A.

1984-06-01

A method for decontaminating uranium product from the Purex 5 process is described. Hydrazine is added to the product uranyl nitrate stream from the Purex process, which contains hexavalent (UO2(2+)) uranium and heptavalent technetius (TcO4-). Technetium in the product stream is reduced and then complexed by the addition of oxalic acid (H2O2O4), and the Tc-oxalate complex is readily separated from the 10 uranium by solvent extraction with 30 vol % tributyl phosphate in n-dodecane.

Determination of uranium in zircon

USGS Publications Warehouse

Cuttitta, F.; Daniels, G.J.

1959-01-01

A routine fluorimetric procedure is described for the determination of trace amounts of uranium in zircon. It employs the direct extraction of uranyl nitrate with ethyl acetate using phosphate as a retainer for zirconium. Submicrogram amounts or uranium are separated in the presence of 100,000 times the amount of zirconium. The modified procedure has been worked out using synthetic mixtures of known composition and zircon. Results of analyses have an accuracy of 97-98% of the contained uranium and a standard deviation of less than 2.5%. ?? 1959.

Determination of uranyl incorporation into biogenic manganese oxides using X-ray absorption spectroscopy and scattering

USGS Publications Warehouse

Webb, S.M.; Fuller, C.C.; Tebo, B.M.; Bargar, J.R.

2006-01-01

Biogenic manganese oxides are common and an important source of reactive mineral surfaces in the environment that may be potentially enhanced in bioremediation cases to improve natural attenuation. Experiments were performed in which the uranyl ion, UO22+ (U(VI)), at various concentrations was present during manganese oxide biogenesis. At all concentrations, there was strong uptake of U onto the oxides. Synchrotron-based extended X-ray absorption fine structure (EXAFS) spectroscopy and X-ray diffraction (XRD) studies were carried out to determine the molecular-scale mechanism by which uranyl is incorporated into the oxide and how this incorporation affects the resulting manganese oxide structure and mineralogy. The EXAFS experiments show that at low concentrations (2 mol % U, >4 ??M U(VI) in solution), the presence of U(VI) affects the stability and structure of the Mn oxide to form poorly ordered Mn oxide tunnel structures, similar to todorokite. EXAFS modeling shows that uranyl is present in these oxides predominantly in the tunnels of the Mn oxide structure in a tridentate complex. Observations by XRD corroborate these results. Structural incorporation may lead to more stable U(VI) sequestration that may be suitable for remediation uses. These observations, combined with the very high uptake capacity of the Mn oxides, imply that Mn-oxidizing bacteria may significantly influence dissolved U(VI) concentrations in impacted waters via sorption and incorporation into Mn oxide biominerals. ?? 2006 American Chemical Society.

Spectroscopy and DFT studies of uranyl carbonate, rutherfordine, UO2CO3: a model for uranium transport, carbon dioxide sequestration, and seawater species

NASA Astrophysics Data System (ADS)

Kalashnyk, N.; Perry, D. L.; Massuyeau, F.; Faulques, E.

2017-12-01

Several optical microprobe experiments of the anhydrous uranium carbonate—rutherfordine—are presented in this work and compared to periodic density functional theory results. Rutherfordine is the simplest uranyl carbonate and constitutes an ideal model system for the study of the rich uranium carbonate family relevant for environmental sustainability. Micro-Raman, micro-reflectance, and micro-photoluminescence (PL) spectroscopy studies have been carried out in situ on native, micrometer-sized crystals. The sensitivity of these techniques is sufficient to analyze minute amounts of samples in natural environments without using x-ray analysis. In addition, very intense micro-PL and micro-reflectance spectra that were not reported before add new results on the ground and excited states of this mineral. The optical gap value determined experimentally is found at about 2.6-2.8 eV. Optimized geometry, band structure, and phonon spectra have been calculated. The main vibrational lines are identified and predicted by this theoretical study. This work is pertinent for optical spectroscopy, for identification of uranyl species in various environmental settings, and for nuclear forensic analysis.

Uranium speciation in acid waste-weathered sediments: The role of aging and phosphate amendments

DOE PAGES

Perdrial, Nicolas; Vázquez-Ortega, Angélica; Wang, Guohui; ...

2017-12-05

Uranium speciation and lability are strongly coupled to mineral transformations in silicate sediments, particularly for sediments subjected to weathering in acidic, high-level radioactive waste, as occurred at the Department of Energy's Hanford (WA) site. Here, uncontaminated Hanford sediments were reacted for 365 days with acidic (pH 3), uranium-bearing waste solutions, with and without phosphate in batch experiments, prior to detailed characterizations using electron microscopy, x-ray diffraction and x-ray absorption spectroscopy. In PO 4-reactant free systems, uranium speciation was controlled initially by precipitation of compreignacite [K 2(UO 2) 6O 4(OH) 6·8H 2O]- and becquerelite [Ca(UO 2) 6O 4(OH) 6·8H 2O]-like species.more » Subsequent further removal of uranium coincided with that of Si and accumulation of boltwoodite, [(K, Na)(UO 2) 2O 4(HSiO 4) 2•0.5(H 2O)]-like species of uranium at 180 and 365 days. When present, PO 4 exerted a direct and strong control over U speciation. Furthermore, the detection of meta-ankoleite, [K 2(UO 2) 2O 4(PO 4) 2·6H 2O] at all reaction times when U was present emphasizes the importance of dissolved phosphate as a control on U speciation. Here, meta-ankoleite appears well crystallized and when it occurs as the principal product of sediment weathering, its low solubility is expected to limit dissolved U(VI) concentrations in groundwater. Although boltwoodite solubility is also low, it is formed more slowly (and only when PO 4 is absent), after initial precipitation of more soluble, less crystalline uranyl hydroxides. In the context of Hanford crib waste our results suggest that with PO 4 present, nearly all uranium would have precipitated in the upper soil.« less

Uranium speciation in acid waste-weathered sediments: The role of aging and phosphate amendments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perdrial, Nicolas; Vázquez-Ortega, Angélica; Wang, Guohui

Uranium speciation and lability are strongly coupled to mineral transformations in silicate sediments, particularly for sediments subjected to weathering in acidic, high-level radioactive waste, as occurred at the Department of Energy's Hanford (WA) site. In this study, uncontaminated Hanford sediments were reacted for 365 days with acidic (pH 3), uranium-bearing waste solutions, with and without phosphate in batch experiments, prior to detailed characterizations using electron microscopy, x-ray diffraction and x-ray absorption spectroscopy. In PO(4)(-)reactant free systems, uranium speciation was controlled initially by precipitation of compreignacite [K-2(UO2)(6)O-4(OH)(6)center dot 8H(2)O]-and becquerelite [Ca(UO2)(6)O-4(OH)(6)center dot 8H(2)O]-like species. Subsequent further removal of uranium coincided withmore » that of Si and accumulation of boltwoodite, [(K, Na)(UO2)(2)O-4(HSiO4)(2)center dot 0.5(H2O)]-like species of uranium at 180 and 365 days. When present, PO4 exerted a direct and strong control over U speciation. The detection of meta-ankoleite, [K-2(UO2)(2)O-4(PO4)(2)center dot 6H(2)O] at all reaction times when U was present emphasizes the importance of dissolved phosphate as a control on U speciation. Here, meta-ankoleite appears well crystallized and when it occurs as the principal product of sediment weathering, its low solubility is expected to limit dissolved U(VI) concentrations in groundwater. Although boltwoodite solubility is also low, it is formed more slowly (and only when PO4 is absent), after initial precipitation of more soluble, less crystalline uranyl hydroxides. In the context of Hanford crib waste our results suggest that with PO4 present, nearly all uranium would have precipitated in the upper soil.« less

Uranium speciation in acid waste-weathered sediments: The role of aging and phosphate amendments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perdrial, Nicolas; Vázquez-Ortega, Angélica; Wang, Guohui

Uranium speciation and lability are strongly coupled to mineral transformations in silicate sediments, particularly for sediments subjected to weathering in acidic, high-level radioactive waste, as occurred at the Department of Energy's Hanford (WA) site. Here, uncontaminated Hanford sediments were reacted for 365 days with acidic (pH 3), uranium-bearing waste solutions, with and without phosphate in batch experiments, prior to detailed characterizations using electron microscopy, x-ray diffraction and x-ray absorption spectroscopy. In PO 4-reactant free systems, uranium speciation was controlled initially by precipitation of compreignacite [K 2(UO 2) 6O 4(OH) 6·8H 2O]- and becquerelite [Ca(UO 2) 6O 4(OH) 6·8H 2O]-like species.more » Subsequent further removal of uranium coincided with that of Si and accumulation of boltwoodite, [(K, Na)(UO 2) 2O 4(HSiO 4) 2•0.5(H 2O)]-like species of uranium at 180 and 365 days. When present, PO 4 exerted a direct and strong control over U speciation. Furthermore, the detection of meta-ankoleite, [K 2(UO 2) 2O 4(PO 4) 2·6H 2O] at all reaction times when U was present emphasizes the importance of dissolved phosphate as a control on U speciation. Here, meta-ankoleite appears well crystallized and when it occurs as the principal product of sediment weathering, its low solubility is expected to limit dissolved U(VI) concentrations in groundwater. Although boltwoodite solubility is also low, it is formed more slowly (and only when PO 4 is absent), after initial precipitation of more soluble, less crystalline uranyl hydroxides. In the context of Hanford crib waste our results suggest that with PO 4 present, nearly all uranium would have precipitated in the upper soil.« less

Mineral resource of the month: phosphate rock

USGS Publications Warehouse

Jasinski, Stephen M.

2007-01-01

Phosphate rock minerals provide the only significant global resources of phosphorus, which is an essential element for plant and animal nutrition. Phosphate rock is used primarily as a principal component of nitrogen-phosphorus-potassium fertilizers, but also to produce elemental phosphorus and animal feed.

Uranium extraction from TRISO-coated fuel particles using supercritical CO2 containing tri-n-butyl phosphate.

PubMed

Zhu, Liyang; Duan, Wuhua; Xu, Jingming; Zhu, Yongjun

2012-11-30

High-temperature gas-cooled reactors (HTGRs) are advanced nuclear systems that will receive heavy use in the future. It is important to develop spent nuclear fuel reprocessing technologies for HTGR. A new method for recovering uranium from tristructural-isotropic (TRISO-) coated fuel particles with supercritical CO(2) containing tri-n-butyl phosphate (TBP) as a complexing agent was investigated. TRISO-coated fuel particles from HTGR fuel elements were first crushed to expose UO(2) pellet fuel kernels. The crushed TRISO-coated fuel particles were then treated under O(2) stream at 750°C, resulting in a mixture of U(3)O(8) powder and SiC shells. The conversion of U(3)O(8) into solid uranyl nitrate by its reaction with liquid N(2)O(4) in the presence of a small amount of water was carried out. Complete conversion was achieved after 60 min of reaction at 80°C, whereas the SiC shells were not converted by N(2)O(4). Uranyl nitrate in the converted mixture was extracted with supercritical CO(2) containing TBP. The cumulative extraction efficiency was above 98% after 20 min of online extraction at 50°C and 25 MPa, whereas the SiC shells were not extracted by TBP. The results suggest an attractive strategy for reprocessing spent nuclear fuel from HTGR to minimize the generation of secondary radioactive waste. Copyright © 2012 Elsevier B.V. All rights reserved.

Erythrocytes of uranium miners: the activity of the pentose phosphate pathway

PubMed Central

Vích, Z.; Novosad, F.; Brychtová, V.

1970-01-01

Vích, Z., Novosad, F., and Brychtová, V. (1970).Brit. J. industr. Med.,27, 287-290. Erythrocytes of uranium miners: the activity of the pentose phosphate pathway. The functioning of erythrocytes was studied by determination of the activity of the pentose phosphate pathway in 431 individuals - 221 uranium miners, 42 employees of a uranium ore trimming station (30 of whom were exposed), 36 former uranium miners, 32 coal miners, and 100 persons not working in mines and with no previous exposure. In the groups exposed to long-term occupational radiation, the activity of the pentose phosphate cycle was found to be enhanced. This finding was interpreted as evidence for a change in the functional state of the erythrocytes in exposed persons due to the effects of radiation on the genesis of red cells in the bone marrow. PMID:5448126

International Strategic Minerals Inventory summary report; phosphate

USGS Publications Warehouse

Krauss, Ulrich H.; Saam, Henning G.; Schmidt, Helmut

1984-01-01

Major world resources of phosphate, a strategic mineral commodity, are described in this summary report of information in the International Strategic Minerals Inventory {ISMI}. ISMI is a cooperative data-collection effort of earth-science and mineral-resource agencies in Australia, Canada, the Federal Republic of Germany, the Republic of South Africa, and the United States of America. This report, designed to be of benefit to policy analysts, contains two parts. Part I presents an overview of the resources and potential supply of phosphate on the basis of inventory information. Part II contains tables of some of the geologic information and mineral-resource and production data that were collected by ISMI participants.

Separation of Depleted Uranium From Soil

DTIC Science & Technology

2009-03-01

order to remove the metallic DU present in these soils. This procedure would re- duce the amount of time that metallic uranium could undergo corrosion ...slow corrosion is not sufficient to ignite the uranium . Unfired rod Weathered, unfired rod with yellow uranyl salt deposits Figure 1. Comparison...resulting in less downward movement. Interactions between uranium corrosion products and soil mineral and organic components can also affect

Regulation of Soluble Phosphate on the Ability of Phytate Mineralization and β-Propeller Phytase Gene Expression of Pseudomonas fluorescens JZ-DZ1, a Phytate-Mineralizing Rhizobacterium.

PubMed

Shen, Lan; Wu, Xiao-Qin; Zeng, Qing-Wei; Liu, Hong-Bin

2016-12-01

Phytate-mineralizing rhizobacteria (PMR) play an important role in providing phosphorus for the sustainable plant growth. It is important to investigate the ability of PMR to produce phytase under different phosphate levels for its application. The effects of different concentrations of soluble phosphate on the ability of phytate mineralization of Pseudomonas fluorescens JZ-DZ1, a phytate-mineralizing rhizobacterium, were investigated in both solid and liquid media. The results on solid media showed that halo zone width gradually reduced with concentrations of soluble phosphate increasing from 0.05 to 20 mM, indicating the reduction of the ability of phytate mineralization. The results were consistent with the quantitative detection of phytase activity from the overall trend. An 1866-bp β-propeller phytase (BPP) gene (phyPf) was cloned from the strain, and the deduced amino acid sequence of phyPf shared 98 % of identity with a known BPP from Pseudomonas sp. BS10-3 (AJF36073.1). The results of relative real-time quantitative PCR assay showed that the expression of phyPf was induced by a low concentration (0.1 mM) of soluble phosphate, suggesting that BPP secretion was regulated by gene phyPf. The BPP-harboring bacterium P. fluorescens JZ-DZ1 with low phosphate-inducible ability of phytate mineralization could be potentially applied to promote phosphorus uptake for plants in the future.

Craters of the Moon National Monument as a Terrestrial Mars Analog: Examination of Mars Analog Phosphate Minerals, Phosphate Mineral Shock-Recovery Experiments, and Phosphate Minerals in Martian Meteorites

NASA Astrophysics Data System (ADS)

Adcock, C. T.; Hausrath, E.; Tschauner, O. D.; Udry, A.

2015-12-01

Martian analogs, meteorites, and data from unmanned missions have greatly advanced our understanding of martian surface and near-surface processes. In particular, terrestrial analogs allow us to investigate Mars-relevant geomorphic, geochemical, petrogenetic, and hydrologic processes, as well as potential habitability. Craters of the Moon National Monument (COTM), located on the Snake River Plain of Idaho in the United States, represents a valuable phosphate-rich Mars analog, allowing us to examine phosphate minerals, important as volatile indicators and potential nutrient providers, under Mars-relevant conditions. COTM is in an arid to semi-arid environment with sub-freezing lows much of the year. Though wetter than present day Mars (24 - 38 cm MAP) [1], COTM may be analogous to a warmer and wetter past Mars. The area is also the locale of numerous lava flows, a number of which have been dated (2,000 to >18,000 y.b.p.) [2]. The flows have experienced weathering over time and thus represent a chronosequence with application to weathering on Mars. The flows have unusual chemistries, including high average phosphate contents (P2O5 1.75 wt% n=23 flows) [2], close to those in rocks analyzed at Gusev Crater, Mars (P2O5 1.79 wt% n=18 rocks) [3]. The Mars-like high phosphorus contents indicate a potential petrogenetic link and are also of astrobiological interest. Further, current samples of Mars phosphate minerals are limited to meteorites which have been heavily shocked - COTM represents a potential pre-shock and geochemical analog to Mars. We investigated weathering on COTM basalts and shock effects on Mars-relevant phosphate minerals. We used scanning electron microscopy, backscattered electron imagery, and X-Ray analysis/mapping to investigate COTM thin sections. Synchrotron diffraction was used to investigate martian meteorites and laboratory shocked Mars/COTM-relevant minerals for comparison. Results of our investigations indicate porosity development correlates with flow age, and shock alteration of phosphate minerals obscures the original phosphate mineralogy in martian meteorites. Thus COTM represents an important chronosequence and pre-shock mineralogy analog for Mars. [1] Vaughan et al. (2008) SSSAJ 75, [2] Kuntz, et al. (1992) GSA Mem. 179, [3] Adcock et al. (2013) Nat. Geos. 6.

WET FLUORIDE SEPARATION METHOD

DOEpatents

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

1958-11-25

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

Separation of uranium from technetium in recovery of spent nuclear fuel

DOEpatents

Friedman, H.A.

1984-06-13

A method for decontaminating uranium product from the Purex 5 process comprises addition of hydrazine to the product uranyl nitrate stream from the Purex process, which contains hexavalent (UO/sub 2//sup 2 +/) uranium and heptavalent technetium (TcO/sub 4/-). Technetium in the product stream is reduced and then complexed by the addition of oxalic acid (H/sub 2/C/sub 2/O/sub 4/), and the Tc-oxalate complex is readily separated from the 10 uranium by solvent extraction with 30 vol % tributyl phosphate in n-dodecane.

Separation of uranium from technetium in recovery of spent nuclear fuel

DOEpatents

Friedman, Horace A.

1985-01-01

A method for decontaminating uranium product from the Purex process comprises addition of hydrazine to the product uranyl nitrate stream from the Purex process, which contains hexavalent (UO.sub.2.sup.2+) uranium and heptavalent technetium (TcO.sub.4 -). Technetium in the product stream is reduced and then complexed by the addition of oxalic acid (H.sub.2 C.sub.2 O.sub.4), and the Tc-oxalate complex is readily separated from the uranium by solvent extraction with 30 vol. % tributyl phosphate in n-dodecane.

URANIUM DECONTAMINATION WITH RESPECT TO ZIRCONIUM

DOEpatents

Vogler, S.; Beederman, M.

1961-05-01

A process is given for separating uranium values from a nitric acid aqueous solution containing uranyl values, zirconium values and tetravalent plutonium values. The process comprises contacting said solution with a substantially water-immiscible liquid organic solvent containing alkyl phosphate, separating an organic extract phase containing the uranium, zirconium, and tetravalent plutonium values from an aqueous raffinate, contacting said organic extract phase with an aqueous solution 2M to 7M in nitric acid and also containing an oxalate ion-containing substance, and separating a uranium- containing organic raffinate from aqueous zirconium- and plutonium-containing extract phase.

Fabrication of mineralized electrospun PLGA and PLGA/gelatin nanofibers and their potential in bone tissue engineering.

PubMed

Meng, Z X; Li, H F; Sun, Z Z; Zheng, W; Zheng, Y F

2013-03-01

Surface mineralization is an effective method to produce calcium phosphate apatite coating on the surface of bone tissue scaffold which could create an osteophilic environment similar to the natural extracellular matrix for bone cells. In this study, we prepared mineralized poly(D,L-lactide-co-glycolide) (PLGA) and PLGA/gelatin electrospun nanofibers via depositing calcium phosphate apatite coating on the surface of these nanofibers to fabricate bone tissue engineering scaffolds by concentrated simulated body fluid method, supersaturated calcification solution method and alternate soaking method. The apatite products were characterized by the scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), and X-ray diffractometry (XRD) methods. A large amount of calcium phosphate apatite composed of dicalcium phosphate dihydrate (DCPD), hydroxyapatite (HA) and octacalcium phosphate (OCP) was deposited on the surface of resulting nanofibers in short times via three mineralizing methods. A larger amount of calcium phosphate was deposited on the surface of PLGA/gelatin nanofibers rather than PLGA nanofibers because gelatin acted as nucleation center for the formation of calcium phosphate. The cell culture experiments revealed that the difference of morphology and components of calcium phosphate apatite did not show much influence on the cell adhesion, proliferation and activity. Copyright © 2012 Elsevier B.V. All rights reserved.

Surface catalysis of uranium(VI) reduction by iron(II)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liger, E.; Charlet, L.; Van Cappellen, P.

1999-10-01

Colloidal hematite ({alpha}-Fe{sub 2}O{sub 3}) is used as model solid to investigate the kinetic effect of specific adsorption interactions on the chemical reduction of uranyl (U{sup VI}O{sub 2}{sup 2+}) by ferrous iron. Acid-base titrations and Fe(II) and uranyl adsorption experiments are performed on hematite suspensions, under O{sub 2}- and CO{sub 2}-free conditions. The results are explained in terms of a constant capacitance surface complexation model of the hematite-aqueous solution interface. Two distinct Fe(II) surface complexes are required to reproduce the data: ({equivalent{underscore}to}Fe{sup III}OFe{sup II}){sup +} (or {equivalent{underscore}to}Fe{sup III}OFe{sup II}(OH{sub 2}){sub n}{sup +}) and {equivalent{underscore}to}Fe{sup III}OFe{sup II}OH{sup 0} (or {equivalent{underscore}to}Fe{sup III}OFe{supmore » II}(OH{sub 2}){sub n{minus}1}OH{sup 0}). The latter complex represents a significant fraction of total adsorbed Fe(II) at pH {gt} 6.5. Uranyl binding to the hematite particles is characterized by a sharp adsorption edge between pH 4 and pH 5.5. Because of the absence of competing aqueous carbonate complexes, uranyl remains completely adsorbed at pH {gt} 7. A single mononuclear surface complex accounts for the adsorption of uranyl over the entire range of experimental conditions. Although thermodynamically feasible, no reaction between uranyl and Fe(II) is observed in homogeneous solution at pH 7.5, for periods of up to three days. In hematite suspensions, however, surface-bound uranyl reacts on a time scale of hours. Based on Fourier Transformed Infrared spectra, chemical reduction of U(VI) is inferred to be the mechanism responsible for the disappearance of uranyl. The kinetics of uranyl reduction are quantified by measuring the decrease with time of the concentration of U(VI) extractable from the hematite particles by NaHCO{sub 3}. In the presence of excess Fe(II), the initial rate of U(VI) reduction exhibits a first-order dependence on the concentration of adsorbed uranyl. The pseudo-first-order rate constant varies with pH (range, 6--7.5) and the total (dissolved + adsorbed) concentration of Fe(II) (range, 2--160 {micro}M). When analyzing the rate data in terms of the calculated surface speciation, the variability of the rate constant can be accounted for entirely by changes in the concentration of the Fe(II) monohydroxo surface complex {equivalent{underscore}to}Fe{sup III}OFe{sup II}OH{sup 0}. Therefore, the rate law is derived for the hematite-catalyzed reduction of uranyl by Fe(II), where the bimolecular rate constant {kappa} has a value of 399 {+-} 25 M{sup {minus}1} min{sup {minus}1} at 25 C. The hydroxo surface complex is the rate-controlling reductant species, because it provides the most favorable coordination environment in which electrons are removed from Fe(II). Natural particulate matter collected in the hypolimnion of a seasonally stratified lake also causes the rapid reduction of uranyl by Fe(II), Ferrihydrite, identified in the particulate matter by X-ray diffraction, is one possible mineral phase accelerating the reaction between U(VI) and Fe(II). At near-neutral pH and total Fe(II) levels less than 1 mM, the pseudo-first-order rate constants of chemical U(VI) reduction, measured in the presence of the hematite and lake particles, are of the same order of magnitude as the highest corresponding rate coefficients for enzymatic U(VI) reduction in bacterial cultures. Hence, based on the results of this study, surface-catalyzed U(VI) reduction by Fe(II) is expected to be a major pathway of uranium immobilization in a wide range of redox-stratified environments.« less

Regularities in Low-Temperature Phosphatization of Silicates

NASA Astrophysics Data System (ADS)

Savenko, A. V.

2018-01-01

The regularities in low-temperature phosphatization of silicates are defined from long-term experiments on the interaction between different silicate minerals and phosphate-bearing solutions in a wide range of medium acidity. It is shown that the parameters of the reaction of phosphatization of hornblende, orthoclase, and labradorite have the same values as for clayey minerals (kaolinite and montmorillonite). This effect may appear, if phosphotization proceeds, not after silicate minerals with a different structure and composition, but after a secondary silicate phase formed upon interaction between silicates and water and stable in a certain pH range. Variation in the parameters of the reaction of phosphatization at pH ≈ 1.8 is due to the stability of the silicate phase different from that at higher pH values.

Uranium minerals in Oligocene gypsum near Chadron, Dawes County, Nebraska

USGS Publications Warehouse

Dunham, R.J.

1955-01-01

Carnotite, sabugalite [HAI(UO2)4(PO4)4 • 16H2O] and autunite occur in the basal 25 feet of a 270-foot sequence of nonmarine bedded gypsum and gypsiferous clay in the Brule formation of Oligocene age about 12 miles northeast of Chadron in northeastern Dawes County, Nebraska. Uranium minerals are visible at only two localities and are associated with carbonaceous matter. Elsewhere the basal 25 feet of the gypsum sequence is interbedded with carbonate rocks and is weakly but persistently uraniferous. Uranium probably was emplaced from above by uranyl solutions rich in sulfate.

Bone Alkaline Phosphatase and Tartrate-Resistant Acid Phosphatase: Potential Co-regulators of Bone Mineralization.

PubMed

Halling Linder, Cecilia; Ek-Rylander, Barbro; Krumpel, Michael; Norgård, Maria; Narisawa, Sonoko; Millán, José Luis; Andersson, Göran; Magnusson, Per

2017-07-01

Phosphorylated osteopontin (OPN) inhibits hydroxyapatite crystal formation and growth, and bone alkaline phosphatase (BALP) promotes extracellular mineralization via the release of inorganic phosphate from the mineralization inhibitor inorganic pyrophosphate (PPi). Tartrate-resistant acid phosphatase (TRAP), produced by osteoclasts, osteoblasts, and osteocytes, exhibits potent phosphatase activity towards OPN; however, its potential capacity as a regulator of mineralization has not previously been addressed. We compared the efficiency of BALP and TRAP towards the endogenous substrates for BALP, i.e., PPi and pyridoxal 5'-phosphate (PLP), and their impact on mineralization in vitro via dephosphorylation of bovine milk OPN. TRAP showed higher phosphatase activity towards phosphorylated OPN and PPi compared to BALP, whereas the activity of TRAP and BALP towards PLP was comparable. Bovine milk OPN could be completely dephosphorylated by TRAP, liberating all its 28 phosphates, whereas BALP dephosphorylated at most 10 phosphates. OPN, dephosphorylated by either BALP or TRAP, showed a partially or completely attenuated phosphorylation-dependent inhibitory capacity, respectively, compared to native OPN on the formation of mineralized nodules. Thus, there are phosphorylations in OPN important for inhibition of mineralization that are removed by TRAP but not by BALP. In conclusion, our data indicate that both BALP and TRAP can alleviate the inhibitory effect of OPN on mineralization, suggesting a potential role for TRAP in skeletal mineralization. Further studies are warranted to explore the possible physiological relevance of TRAP in bone mineralization.

Citrate bridges between mineral platelets in bone

PubMed Central

Davies, Erika; Müller, Karin H.; Wong, Wai Ching; Pickard, Chris J.; Reid, David G.; Skepper, Jeremy N.; Duer, Melinda J.

2014-01-01

We provide evidence that citrate anions bridge between mineral platelets in bone and hypothesize that their presence acts to maintain separate platelets with disordered regions between them rather than gradual transformations into larger, more ordered blocks of mineral. To assess this hypothesis, we take as a model for a citrate bridging between layers of calcium phosphate mineral a double salt octacalcium phosphate citrate (OCP-citrate). We use a combination of multinuclear solid-state NMR spectroscopy, powder X-ray diffraction, and first principles electronic structure calculations to propose a quantitative structure for this material, in which citrate anions reside in a hydrated layer, bridging between apatitic layers. To assess the relevance of such a structure in native bone mineral, we present for the first time, to our knowledge, 17O NMR data on bone and compare them with 17O NMR data for OCP-citrate and other calcium phosphate minerals relevant to bone. The proposed structural model that we deduce from this work for bone mineral is a layered structure with thin apatitic platelets sandwiched between OCP-citrate–like hydrated layers. Such a structure can explain a number of known structural features of bone mineral: the thin, plate-like morphology of mature bone mineral crystals, the presence of significant quantities of strongly bound water molecules, and the relatively high concentration of hydrogen phosphate as well as the maintenance of a disordered region between mineral platelets. PMID:24706850

Extracellular matrix mineralization in periodontal tissues: Noncollagenous matrix proteins, enzymes, and relationship to hypophosphatasia and X-linked hypophosphatemia

PubMed Central

McKee, Marc D.; Hoac, Betty; Addison, William N.; Barros, Nilana M.T.; Millán, José Luis; Chaussain, Catherine

2013-01-01

As broadly demonstrated for the formation of a functional skeleton, proper mineralization of periodontal alveolar bone and teeth – where calcium phosphate crystals are deposited and grow within an extracellular matrix – is essential to dental function. Mineralization defects in tooth dentin and cementum of the periodontium invariably lead to a weak (soft or brittle) dentition such that teeth become loose and prone to infection and are lost prematurely. Mineralization of the extremities of periodontal ligament fibres (Sharpey's fibres) where they insert into tooth cementum and alveolar bone is also essential for the function of the tooth suspensory apparatus in occlusion and mastication. Molecular determinants of mineralization in these tissues include mineral ion concentrations (phosphate and calcium), pyrophosphate, small integrin-binding ligand N-linked glycoproteins (SIBLINGs), and matrix vesicles. Amongst the enzymes important in regulating these mineralization determinants, two are discussed at length here with clinical examples given, namely tissue-nonspecific alkaline phosphatase (TNAP) and phosphate-regulating gene with homologies to endopeptidases on the X chromosome (PHEX). Inactivating mutations in these enzymes in humans and in mouse models lead to the soft bones and teeth characteristic of hypophosphatasia (HPP) and X-linked hypophosphatemia (XLH), respectively, where levels of local and systemic circulating mineralization determinants are perturbed. In XLH, in addition to renal phosphate wasting causing low circulating phosphate levels, phosphorylated mineralization-regulating SIBLING proteins such as matrix extracellular phosphoglycoprotein (MEPE) and osteopontin (OPN), and the phosphorylated peptides proteolytically released from them such as the acidic serine- and aspartate-rich motif (ASARM) peptide, may accumulate locally to impair mineralization in this disease. PMID:23931057

FT-IR microscopic mappings of early mineralization in chick limb bud mesenchymal cell cultures

NASA Technical Reports Server (NTRS)

Boskey, A. L.; Camacho, N. P.; Mendelsohn, R.; Doty, S. B.; Binderman, I.

1992-01-01

Chick limb bud mesenchymal cells differentiate into chondrocytes and form a cartilaginous matrix in culture. In this study, the mineral formed in different areas within cultures supplemented with 4 mM inorganic phosphate, or 2.5, 5.0, and 10 mM beta-glycerophosphate (beta GP), was characterized by Fourier-transform infrared (FT-IR) microscopy. The relative mineral-to-matrix ratios, and distribution of crystal sizes at specific locations throughout the matrix were measured from day 14 to day 30. The only mineral phase detected was a poorly crystalline apatite. Cultures receiving 4 mM inorganic phosphate had smaller crystals which were less randomly distributed around the cartilage nodules than those in the beta GP-treated cultures. beta GP-induced mineral consisted of larger, more perfect apatite crystals. In cultures receiving 5 or 10 mM beta GP, the relative mineral-to-matrix ratios (calculated from the integrated intensities of the phosphate and amide I bands, respectively) were higher than in the cultures with 4 mM inorganic phosphate or in the in vivo calcified chick cartilage.

Role of Phosphorus Minerals in the Origin of Life on Earth

NASA Astrophysics Data System (ADS)

Gull, M.; Pasek, M. A.

2013-12-01

In the origin of life, phosphorus (P) plays a vital role as it is a key biologic element (1). However, a big question still remains as to how P was incorporated into the first biomolecules as the availability of dissolved P in water is low. Orthophosphate minerals such as apatite, whitelockite and monetite are the major carriers of phosphate on Earth, but these are poorly soluble in water and are inert. The recent discovery of phosphite in Archean rocks (2) suggests that it is likely that some other source of P was present on the early Earth which could very well mix with Hadean Ocean to generate biomolecules. The meteoritic mineral schreibersite (SC thereafter) may have provided reduced P that would corrode into water and generate reactive inorganic P. In this study we present the significance of some important P minerals including apatite, whitelockite, monazite, struvite, monetite and meteoritic mineral SC (or its synthetic analogue Fe3P). Two major aspects of these P minerals were studied; first the release of P into water and second whether phosphorylation of organic compound (glycerol) could be carried out. It was seen all the phosphate minerals such as apatite, whitelockite, monazite and monetite when heated (65-75oC for 8-10 days) with an aqueous solution of 0.5 M glycerol gave no prominent phosphorylated products (P31NMR & mass spectrometry) and released very little amount of phosphate into water and remained inert. Struvite on heating with glycerol gave around 8-10 % of glycerol monophosphates along with phosphate release in the water. When SC (or Fe3P) was heated in an aqueous solution of glycerol it not only yielded 3-6 % glycerol monophosphates but also some glycerol-di-phosphate along with rich species of inorganic P compounds. SC from the meteorite Seymchan also demonstrated phosphorylation of glycerol. Since the prebiotic role of struvite mineral as a prebiotic P mineral is not clearly known (3), this suggests SC was a potential prebiotic P source (4). The beauty of these bio-geologic reactions is the one-pot synthesis of glycerol-1-phosphate, glycerol-2-phosphate along with glycerol-di-phosphate and many inorganic P species (orthophosphate, pyrophosphate, triphosphate, phosphite). This one-pot synthetic route could possibly be one of the most important steps in the emergence of life. The study focuses on the significance of meteoritic based origin of life and how meteorites would have played a significant role in the origin of biological phosphate esters/life on the early earth. Phosphorylation of organic compounds by meteoritic sources

Phosphate Solubilization and Gene Expression of Phosphate-Solubilizing Bacterium Burkholderia multivorans WS-FJ9 under Different Levels of Soluble Phosphate.

PubMed

Zeng, Qingwei; Wu, Xiaoqin; Wang, Jiangchuan; Ding, Xiaolei

2017-04-28

Phosphate-solubilizing bacteria (PSB) have the ability to dissolve insoluble phosphate and enhance soil fertility. However, the growth and mineral phosphate solubilization of PSB could be affected by exogenous soluble phosphate and the mechanism has not been fully understood. In the present study, the growth and mineral phosphate-solubilizing characteristics of PSB strain Burkholderia multivorans WS-FJ9 were investigated at six levels of exogenous soluble phosphate (0, 0.5, 1, 5, 10, and 20 mM). The WS-FJ9 strain showed better growth at high levels of soluble phosphate. The phosphate-solubilizing activity of WS-FJ9 was reduced as the soluble phosphate concentration increased, as well as the production of pyruvic acid. Transcriptome profiling of WS-FJ9 at three levels of exogenous soluble phosphate (0, 5, and 20 mM) identified 446 differentially expressed genes, among which 44 genes were continuously up-regulated when soluble phosphate concentration was increased and 81 genes were continuously down-regulated. Some genes related to cell growth were continuously up-regulated, which would account for the better growth of WS-FJ9 at high levels of soluble phosphate. Genes involved in glucose metabolism, including glycerate kinase, 2-oxoglutarate dehydrogenase, and sugar ABC-type transporter, were continuously down-regulated, which indicates that metabolic channeling of glucose towards the phosphorylative pathway was negatively regulated by soluble phosphate. These findings represent an important first step in understanding the molecular mechanisms of soluble phosphate effects on the growth and mineral phosphate solubilization of PSB.

Characterization of the phosphatic mineral of the barnacle Ibla cumingi at atomic level by solid-state nuclear magnetic resonance: comparison with other phosphatic biominerals

PubMed Central

Reid, David G.; Mason, Matthew J.; Chan, Benny K. K.; Duer, Melinda J.

2012-01-01

Ibliform barnacles are among the few invertebrate animals harnessing calcium phosphate to construct hard tissue. The 31P solid-state NMR (SSNMR) signal from the shell plates of Ibla cumingi (Iblidae) is broader than that of bone, and shifted by ca 1 ppm to low frequency. 1H–31P heteronuclear correlation (HETCOR) experiments show a continuum of different phosphorus/phosphate atomic environments, close to hydrogen populations with resonance frequencies between ca 10 and 20 ppm. Associated 1H and 31P chemical shifts argue the coexistence of weakly (high 31P frequency, low 1H frequency) to more strongly (lower 31P frequency, higher 1H frequency) hydrogen-bonded hydrogen phosphate-like molecular/ionic species. There is no resolved signal from discrete OH− ions. 13C SSNMR shows chitin, protein and other organic biomolecules but, unlike bone, there are no significant atomic scale organic matrix–mineral contacts. The poorly ordered hydrogen phosphate-like iblid mineral is strikingly different, structurally and compositionally, from both vertebrate bone mineral and the more crystalline fluoroapatite of the linguliform brachiopods. It probably represents a previously poorly characterized calcium phosphate biomineral, the evolution of which may have reflected either the chemical conditions of ancestral seas or the mechanical advantages of phosphatic biomineralization over a calcium carbonate equivalent. PMID:22298816

Characterization and in vitro biological evaluation of mineral/osteogenic growth peptide nanocomposites synthesized biomimetically on titanium

NASA Astrophysics Data System (ADS)

Chen, Cen; Kong, Xiangdong; Zhang, Sheng-Min; Lee, In-Seop

2015-04-01

Nanocomposite layers of mineral/osteogenic growth peptide (OGP) were synthesized on calcium phosphate coated titanium substrates by immersing in calcium-phosphate buffer solution containing OGP. Peptide incorporated mineral was characterized by determining quantity loaded, effects on mineral morphology and structure. Also, the biological activity was investigated by cell adhesion, proliferation assay, and measurement of alkaline phosphatase (ALP) activity. X-ray photoelectron spectroscopy (XPS) and micro-bicinchoninic acid (BCA) assay revealed that OGP was successfully incorporated with mineral and the amount was increased with immersion time. Incorporated OGP changed the mineral morphology from sharp plate-like shape to more rounded one, and the octacalcium phosphate structure of the mineral was gradually transformed into apatite. With confocal microscopy to examine the incorporation of fluorescently labeled peptide, OGP was evenly distributed throughout mineral layers. Mineral/OGP nanocomposites promoted cell adhesion and proliferation, and also increased ALP activity of mesenchymal stem cells (MSCs). Results presented here indicated that the mineral/OGP nanocomposites formed on titanium substrates had the potential for applications in dental implants.

Evaluation of the stability of uranyl peroxo-carbonato complex ions in carbonate media at different temperatures.

PubMed

Kim, Kwang-Wook; Lee, Keun-Young; Chung, Dong-Yong; Lee, Eil-Hee; Moon, Jei-Kwon; Shin, Dong-Woo

2012-09-30

This work studied the stability of peroxide in uranyl peroxo carbonato complex ions in a carbonate solution with hydrogen peroxide using absorption and Raman spectroscopies, and evaluated the temperature dependence of the decomposition characteristics of uranyl peroxo carbonato complex ions in the solution. The uranyl peroxo carbonato complex ions self-decomposed more rapidly into uranyl tris-carbonato complex ions in higher temperature carbonate solutions. The concentration of peroxide in the solution without free hydrogen peroxide represents the concentration of uranyl peroxo carbonato complex ions in a mixture of uranyl peroxo carbonato complex and uranyl tris-carbonato complex ions. The self-decomposition of the uranyl peroxo carbonato complex ions was a first order reaction, and its activation energy was evaluated to be 7.144×10(3) J mol(-1). The precipitation of sodium uranium oxide hydroxide occurred when the amount of uranyl tris-carbonato complex ions generated from the decomposition of the uranyl peroxo carbonato complex ions exceeded the solubility of uranyl tris-carbonato ions in the solution at the solution temperature. Copyright © 2012 Elsevier B.V. All rights reserved.

The ultimate mineral processing challenge: Recovery of rare earths, phosphorus and uranium from Florida phosphatic clay

DOE PAGES

Zhang, Patrick; Liang, Haijun; Jin, Zhen; ...

2017-11-01

We report phosphate beneficiation in Florida generates more than one tonne of phosphatic clay, or slime, per tonne of phosphate rock produced. Since the start of the practice of large-scale washing and desliming for phosphate beneficiation, more than 2 Gt of slime has accumulated, containing approximately 600 Mt of phosphate rock, 600 kt of rare earth elements (REEs) and 80 million kilograms of uranium. The recovery of these valuable elements from the phosphatic clay is one of the most challenging endeavors in mineral processing, because the clay is extremely dilute, with an average solids concentration of 3 percent, and finemore » in size, with more than 50 percent having particle size smaller than 2 μm, and it contains nearly 50 percent clay minerals as well as large amounts of magnesium, iron and aluminum. With industry support and under funding from the Critical Materials Institute, the Florida Industrial and Phosphate Research Institute in conjunction with the Oak Ridge National Laboratory undertook the task to recover phosphorus, rare earths and uranium from Florida phosphatic clay. This paper presents the results from the preliminary testing of two approaches. The first approach involves three-stage cycloning using cyclones with diameters of 12.4 cm (5 in.), 5.08 cm (2 in.) and 2.54 cm (1 in.), respectively, to remove clay minerals followed by flotation and leaching. The second approach is a two-step leaching process. In the first step, selective leaching was conducted to remove magnesium, thus allowing the production of phosphoric acid suitable for the manufacture of diammonium phosphate (DAP) in the second leaching step. The results showed that multistage cycloning with small cyclones is necessary to remove clay minerals. Finally, selective leaching at about pH 3.2 using sulfuric acid was found to be effective for removing more than 80 percent of magnesium from the feed with minimal loss of phosphorus.« less

The ultimate mineral processing challenge: Recovery of rare earths, phosphorus and uranium from Florida phosphatic clay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Patrick; Liang, Haijun; Jin, Zhen

We report phosphate beneficiation in Florida generates more than one tonne of phosphatic clay, or slime, per tonne of phosphate rock produced. Since the start of the practice of large-scale washing and desliming for phosphate beneficiation, more than 2 Gt of slime has accumulated, containing approximately 600 Mt of phosphate rock, 600 kt of rare earth elements (REEs) and 80 million kilograms of uranium. The recovery of these valuable elements from the phosphatic clay is one of the most challenging endeavors in mineral processing, because the clay is extremely dilute, with an average solids concentration of 3 percent, and finemore » in size, with more than 50 percent having particle size smaller than 2 μm, and it contains nearly 50 percent clay minerals as well as large amounts of magnesium, iron and aluminum. With industry support and under funding from the Critical Materials Institute, the Florida Industrial and Phosphate Research Institute in conjunction with the Oak Ridge National Laboratory undertook the task to recover phosphorus, rare earths and uranium from Florida phosphatic clay. This paper presents the results from the preliminary testing of two approaches. The first approach involves three-stage cycloning using cyclones with diameters of 12.4 cm (5 in.), 5.08 cm (2 in.) and 2.54 cm (1 in.), respectively, to remove clay minerals followed by flotation and leaching. The second approach is a two-step leaching process. In the first step, selective leaching was conducted to remove magnesium, thus allowing the production of phosphoric acid suitable for the manufacture of diammonium phosphate (DAP) in the second leaching step. The results showed that multistage cycloning with small cyclones is necessary to remove clay minerals. Finally, selective leaching at about pH 3.2 using sulfuric acid was found to be effective for removing more than 80 percent of magnesium from the feed with minimal loss of phosphorus.« less

Agronomic and environmental consequences of using liquid mineral concentrates on arable farms.

PubMed

Schils, René L M; Postma, Romke; van Rotterdam, Debby; Zwart, Kor B

2015-12-01

In regions with intensive livestock systems, the processing of manure into liquid mineral concentrates is seen as an option to increase the nutrient use efficiency of manures. The agricultural sector anticipates that these products may in future be regarded as regular mineral fertilisers. We assessed the agronomic suitability and impact on greenhouse gas (GHG) and ammonia emissions of using liquid mineral concentrates on arable farms. The phosphate requirements on arable farms were largely met by raw pig slurry, given its large regional availability. After the initial nutrient input by means of pig slurry, the nitrogen/phosphate ratio of the remaining nutrient crop requirements determined the additional amount of liquid mineral concentrates that can be used. For sandy soils, liquid mineral concentrates could supply 50% of the nitrogen requirement, whereas for clay soils the concentrates did not meet the required nitrogen/phosphate ratio. The total GHG emissions per kg of plant available nitrogen ranged from -65 to 33 kg CO2 -equivalents. It increased in the order digestates < mineral fertiliser < raw slurries. Liquid mineral concentrates had limited added value for arable farms. For an increased suitability it is necessary that liquid mineral concentrates do not contain phosphate and that the nitrogen availability is increased. In the manure-processing chain, anaerobic digestion had a dominant and beneficial effect on GHG emissions. © 2015 Society of Chemical Industry.

43 CFR 3511.10 - Do certain leases allow me to mine other commodities as well?

Code of Federal Regulations, 2014 CFR

2014-10-01

... processing or refining of phosphate, phosphate rock, and associated minerals mined from the leased lands. You... (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LEASING OF SOLID MINERALS OTHER THAN COAL AND OIL SHALE Lease Terms and Conditions § 3511.10 Do certain leases allow me to...

43 CFR 3511.10 - Do certain leases allow me to mine other commodities as well?

Code of Federal Regulations, 2013 CFR

2013-10-01

... processing or refining of phosphate, phosphate rock, and associated minerals mined from the leased lands. You... (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LEASING OF SOLID MINERALS OTHER THAN COAL AND OIL SHALE Lease Terms and Conditions § 3511.10 Do certain leases allow me to...

Nanophase iron phosphate, iron arsenate, iron vanadate, and iron molybdate minerals synthesized within the protein cage of ferritin.

PubMed

Polanams, Jup; Ray, Alisha D; Watt, Richard K

2005-05-02

Nanoparticles of iron phosphate, iron arsenate, iron molybdate, and iron vanadate were synthesized within the 8 nm interior of ferritin. The synthesis involved reacting Fe(II) with ferritin in a buffered solution at pH 7.4 in the presence of phosphate, arsenate, vanadate, or molybdate. O2 was used as the oxidant to deposit the Fe(III) mineral inside ferritin. The rate of iron incorporation into ferritin was stimulated when oxo-anions were present. The simultaneous deposition of both iron and the oxo-anion was confirmed by elemental analysis and energy-dispersive X-ray analysis. The ferritin samples containing iron and one of the oxo-anions possessed different UV/vis spectra depending on the anion used during mineral formation. TEM analysis showed mineral cores with approximately 8 nm mineral particles consistent with the formation of mineral phases inside ferritin.

Phosphate mineral formation in Lake Baikal sediments and implications for paleoclimate

NASA Astrophysics Data System (ADS)

Fagel, N.; Alleman, L. Y.; André, L.; Cloots, R.; Hatert, F.; Juvigné, E.; Renson, V.

2003-04-01

The more than 20 million years old Lake Baikal sedimentary record provides a good climate archive. While most paleoclimate reconstructions are mainly based on biotic proxies, we tested in this study other minerogenic tracers. In particular, it was suggested that the formation of authigenic and/or diagenetic phosphate minerals in Baïkal sediments underlines transitions from glacial to interglacial periods (Deike et al., 1997). The phosphate mineral formation previously evidenced (Müller et al., 2002) may be sensitive to suspended sediment concentrations: glacial periods are characterised by high detrital discharge, interglacial intervals are marked by low detrital supply but high biogenic sedimentation. Phosphate minerals were observed in Baïkal sediments from recent to 65 kyr BP. Their abundance was related to the sedimentation rate, the phosphate enrichment layers being particularly common on low sedimentation site, i.e., the Academician Ridge. Major and trace elements have been analysed by ICP-AES and ICP-MS on four cores drilled on topographic hills, in the southern basin (Posolsky bank, CON01-604), in the central part (Academician Ridge, VER98-1-3 and VER98-1-14) and in the northern basin (Continent Ridge, CON01-603). The geochemical signature is consistent with the occurrence of Mn-Fe-phosphate minerals. For instance P2O5 reaches up to 3% wt. relative to a mean value of 0.3 in the background sediment, MnO2 presents an enrichment factor up to 6. There is no associated enrichment in any of the trace elements measured at the same levels. In the sediments, those P-Mn-Fe rich levels are related either to sparse millimetric dark concretions or to a layer (or a group of layers) defined by an alignment of numerous concretions but there is no so-called crusts. The concretions, isolated by >63 mm sieving, present a lamellar morphology. They are identified as Fe-phosphate phases with a variable proportion of Mn. The powder diffraction diagram is consistent with vivianite, a mineral that has been previously characterized in lacustrine sediments worldwide, including Baïkal. However, its precise formation process is not yet fully understood. Dean et al. (2002) emphasize that the occurrence of phosphate minerals in Elk lake (USA) is indicative of the paleo-productivity of the water-column. For Deike et al. (2002), phosphate crusts mainly accumulate under slow sedimentation conditions. We discuss the paleo-environmental implications of the occurrence of phosphate minerals in sediments. By studying the distribution of the phosphate concretions in sedimentary columns characterised under different sedimentary conditions, we would like to point up the implications of phosphate minerals for paleoclimate reconstruction. Dean et al., 2002. A 1500-year record of climatic and environmental change in Elk Lake, Cearwater County, Minnesota II : Geochemistry , mineralogy, and stable isotopes. J. Paleolimn. 27, 301-319. Müller et al., 2002. P, As, Sb, Mo, and other elements in sedimentary Fe/Mn layers of Lake Baïkal, Environmental Science and Technology, 36, 411-420. Deike et al., 1997. Formation of ferric iron crusts in quaternnary sediments of Lake Baikal, Russia and implications for paleoclimate. Marine Geology 139, 21-46.

SEPARATION OF URANIUM FROM ZIRCONIUM AND NIOBIUM BY SOLVENT EXTRACTION

DOEpatents

Voiland, E.E.

1958-05-01

A process for separation of the uranium from zirconium and/or niobium values contained in 3 to 7M aqueous nitric acid solutions is described. This is accomplished by adding phosphoric acid anions to the nitric acid solution containing the uranium, zirconium, and/or niobium in an amount sufficient to make the solution 0.05 to 0.2M in phosphate ion and contacting the solution with an organic water-immiscible solvent such as MEK, whereby the uranyl values are taken up by the extract phase while the zirconium and niobium preferentially remain in the aqueous raffinate.

Paracrystalline Disorder from Phosphate Ion Orientation and Substitution in Synthetic Bone Mineral.

PubMed

Marisa, Mary E; Zhou, Shiliang; Melot, Brent C; Peaslee, Graham F; Neilson, James R

2016-12-05

Hydroxyapatite is an inorganic mineral closely resembling the mineral phase in bone. However, as a biological mineral, it is highly disordered, and its composition and atomistic structure remain poorly understood. Here, synchrotron X-ray total scattering and pair distribution function analysis methods provide insight into the nature of atomistic disorder in a synthetic bone mineral analogue, chemically substituted hydroxyapatite. By varying the effective hydrolysis rate and/or carbonate concentration during growth of the mineral, compounds with varied degrees of paracrystallinity are prepared. From advanced simulations constrained by the experimental pair distribution function and density functional theory, the paracrystalline disorder prevalent in these materials appears to result from accommodation of carbonate in the lattice through random displacement of the phosphate groups. Though many substitution modalities are likely to occur in concert, the most predominant substitution places carbonate into the mirror plane of an ideal phosphate site. Understanding the mineralogical imperfections of a biologically analogous hydroxyapatite is important not only to potential bone grafting applications but also to biological mineralization processes themselves.

Apatite mineralization in elasmobranch skeletons via a polyphosphate intermediate

NASA Astrophysics Data System (ADS)

Omelon, Sidney; Lacroix, Nicolas; Lildhar, Levannia; Variola, Fabio; Dean, Mason

2014-05-01

All vertebrate skeletons are stiffened with apatite, a calcium phosphate mineral. Control of apatite mineralization is essential to the growth and repair of the biology of these skeletons, ensuring that apatite is deposited in the correct tissue location at the desired time. The mechanism of this biochemical control remains debated, but must involve increasing the localized apatite saturation state. It was theorized in 1923 that alkaline phosphatase (ALP) activity provides this control mechanism by increasing the inorganic phosphate (Pi) concentration via dephosphorylation of phosphorylated molecules. The ALP substrate for biological apatite is not known. We propose that polyphosphates (polyPs) produced by mitochondria may be the substrate for biological apatite formation by ALP activity. PolyPs (PO3-)n, also known as condensed phosphates, represent a concentrated, bioavailable Pi-storage strategy. Mitochondria import Pi and synthesize phosphate polymers through an unknown biochemical mechanism. When chelated with calcium and/or other cations, the effective P-concentration of these neutrally charged, amorphous, polyP species can be very high (~ 0.5 M), without inducing phosphate mineral crystallization. This P-concentration in the low Pi-concentration biological environment offers a method of concentrating P well above an apatite supersaturation required for nucleation. Bone is the most studied mineralized skeletal tissue. However, locating and analyzing active mineralizing areas is challenging. We studied calcified cartilage skeletons of elasmobranch fishes (sharks, stingrays and relatives) to analyse the phosphate chemistry in this continually mineralizing skeleton. Although the majority of the elasmobranch skeleton is unmineralized cartilage, it is wrapped in an outer layer of mineralized tissue comprised of small tiles called tesserae. These calcified tesserae continually grow through the formation of new mineral on their borders. Co-localization of ALP and polyPs were identified at the mineralizing tessera borders using Raman spectroscopy, fluorescence microscopy and histological methods. Application of exogenous ALP to skeletal tissue cross-sections resulted in polyP disappearance, and Pi production. It is proposed that elasmobranch skeletal cells produce polyP-containing granules as a concentrated P-source, while ALP activity controls when and where Pi is cleaved from polyP, increasing the apatite supersaturation to nucleate apatite minerals in the skeleton. These data support not only interaction of polyP and ALP as a cell-mediated apatite mineralization control mechanism, but also suggest that this mechanism arose millions of years ago and is common to both bony and cartilaginous skeletal systems.

Effect of phosphate on U(VI) sorption to montmorillonite: Ternary complexation and precipitation barriers

NASA Astrophysics Data System (ADS)

Troyer, Lyndsay D.; Maillot, Fabien; Wang, Zheming; Wang, Zimeng; Mehta, Vrajesh S.; Giammar, Daniel E.; Catalano, Jeffrey G.

2016-02-01

Phosphate addition is a potential treatment method to lower the solubility of U(VI) in soil and groundwater systems by causing U(VI) phosphate precipitation as well as enhancing adsorption. Previous work has shown that iron oxide surfaces may facilitate the nucleation of U(VI) phosphate minerals and, that under weakly acidic conditions, phosphate also enhances U(VI) adsorption to such phases. Like iron oxides, clays are important reactive phases in the subsurface but little is known about the interaction of U(VI) and phosphate with these minerals. The effect of aqueous phosphate on U(VI) binding to Wyoming montmorillonite (SWy-2) in air-equilibrated systems was investigated. Equilibrium U(VI) uptake to montmorillonite was determined at pH 4, 6 and 8 at discrete initial phosphate concentrations between 0 and 100 μM. The observed behavior of U(VI) indicates a transition from adsorption to precipitation with increasing total uranium and phosphate concentrations at all pH values. At the highest phosphate concentration examined at each pH value, a barrier to U(VI) phosphate nucleation is observed. At lower concentrations, phosphate has no effect on macroscopic U(VI) adsorption. To assess the mechanisms of U(VI)-phosphate interactions on smectite surfaces, U(VI) speciation was investigated under selected conditions using laser-induced fluorescence spectroscopy (LIFS) and extended X-ray absorption fine-structure (EXAFS) spectroscopy. Samples above the precipitation threshold display EXAFS and LIFS spectral signatures consistent with the autunite family of U(VI) phosphate minerals. However, at lower U(VI) concentrations, changes in LIFS spectra upon phosphate addition suggest that U(VI)-phosphate ternary surface complexes form on the montmorillonite surface at pH 4 and 6 despite the lack of a macroscopic effect on adsorption. The speciation of solid-associated U(VI) below the precipitation threshold at pH 8 is dominated by U(VI)-carbonate surface complexes. This work reveals that ternary complexation may occur without a macroscopic signature, which is attributed to phosphate not appreciably binding to smectite in the absence of U(VI), with U(VI) surface complexes serving as the sole reactive surface sites for phosphate. This study shows that phosphate does not enhance U(VI) adsorption to smectite clay minerals, unlike oxide phases, and that a barrier to homogeneous nucleation of U(VI) phosphates was not affected by the presence of the smectite surface.

Interfacial Interaction of Titania Nanoparticles and Ligated Uranyl Species: A Relativistic DFT Investigation.

PubMed

Zhao, Hong-Bo; Zheng, Ming; Schreckenbach, Georg; Pan, Qing-Jiang

2017-03-06

To understand interfacial behavior of actinides adsorbed onto mineral surfaces and unravel their structure-property relationship, the structures, electronic properties, and energetics of various ligated uranyl species adsorbed onto TiO 2 surface nanoparticle clusters (SNCs) were examined using relativistic density functional theory. Rutile (110) and anatase (101) titania surfaces, experimentally known to be stable, were fully optimized. For the former, models studied include clean and water-free Ti 27 O 64 H 20 (dry), partially hydrated (Ti 27 O 64 H 20 )(H 2 O) 8 (sol) and proton-saturated [(Ti 27 O 64 H 20 )(H 2 O) 8 (H) 2 ] 2+ (sat), while defect-free and defected anatase SNCs involving more than 38 TiO 2 units were considered. The aquouranyl sorption onto rutile SNCs is energetically preferred, with interaction energies of -8.54, -10.36, and -2.39 eV, respectively. Energy decomposition demonstrates that the sorption is dominated by orbital attractive interactions and modified by steric effects. Greater hydrogen-bonding involvement leads to increased orbital interactions (i.e., more negative energy) from dry to sol/sat complexes, while much larger steric interaction in the sat complex significantly reduces the sorption interaction (i.e., more positive energy). For dry SNC, adsorbates were varied from aquo to aquo-carbonato, to carbonato, to hydroxo uranyl species. Longer U-O surf /U-Ti distances and more positive sorption energies were calculated upon introducing carbonato and hydroxo ligands, indicative of weaker uranyl sorption onto the substrate. This is consistent with experimental observations that the uranyl sorption rate decreases upon raising solution pH value or adding carbon dioxide. Anatase SNCs adsorbing aquouranyl are even more exothermic, because more bonds are formed than in the case of rutile. Moreover, the anatase sorption can be tuned by surface defects as well as its Ti and O stoichiometry. All the aquouranyl-SNC complexes show similar character of molecular orbitals and energetic order although differing in highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gaps and orbital energy levels, but changes can be accomplished by adding carbonato and hydroxo ligands.

Uranyl adsorption and surface speciation at the imogolite-water interface: Self-consistent spectroscopic and surface complexation models

USGS Publications Warehouse

Arai, Y.; McBeath, M.; Bargar, J.R.; Joye, J.; Davis, J.A.

2006-01-01

Macro- and molecular-scale knowledge of uranyl (U(VI)) partitioning reactions with soil/sediment mineral components is important in predicting U(VI) transport processes in the vadose zone and aquifers. In this study, U(VI) reactivity and surface speciation on a poorly crystalline aluminosilicate mineral, synthetic imogolite, were investigated using batch adsorption experiments, X-ray absorption spectroscopy (XAS), and surface complexation modeling. U(VI) uptake on imogolite surfaces was greatest at pH ???7-8 (I = 0.1 M NaNO3 solution, suspension density = 0.4 g/L [U(VI)]i = 0.01-30 ??M, equilibration with air). Uranyl uptake decreased with increasing sodium nitrate concentration in the range from 0.02 to 0.5 M. XAS analyses show that two U(VI) inner-sphere (bidentate mononuclear coordination on outer-wall aluminol groups) and one outer-sphere surface species are present on the imogolite surface, and the distribution of the surface species is pH dependent. At pH 8.8, bis-carbonato inner-sphere and tris-carbonato outer-sphere surface species are present. At pH 7, bis- and non-carbonato inner-sphere surface species co-exist, and the fraction of bis-carbonato species increases slightly with increasing I (0.1-0.5 M). At pH 5.3, U(VI) non-carbonato bidentate mononuclear surface species predominate (69%). A triple layer surface complexation model was developed with surface species that are consistent with the XAS analyses and macroscopic adsorption data. The proton stoichiometry of surface reactions was determined from both the pH dependence of U(VI) adsorption data in pH regions of surface species predominance and from bond-valence calculations. The bis-carbonato species required a distribution of surface charge between the surface and ?? charge planes in order to be consistent with both the spectroscopic and macroscopic adsorption data. This research indicates that U(VI)-carbonato ternary species on poorly crystalline aluminosilicate mineral surfaces may be important in controlling U(VI) mobility in low-temperature geochemical environments over a wide pH range (???5-9), even at the partial pressure of carbon dioxide of ambient air (pCO2 = 10-3.45 atm). ?? 2006 Elsevier Inc. All rights reserved.

Origin of coffinite in sedimentary rocks by a sequential adsorption-reduction mechanism.

USGS Publications Warehouse

Goldhaber, M.B.; Hemingway, B.S.; Mohagheghi, A.; Reynolds, R.L.; Northrop, H.R.

1987-01-01

Coffinite is the dominant ore mineral in the V-U ores of the Tony-M mine in the Henry Mts mineral belt of the Colorado Plateau. This orebody was formed at a density-stratified solution interface between uranyl-ion-bearing meteoric water and a saline fluid which was locally reducing. The localization of U at this solution interface occurred by adsorption onto the surfaces of detrital minerals, this adsorption being related to the pH difference between the two fluids. Experimental evidence is presented showing that the adsorption facilitated the reduction of uranium to U(IV). This adsorbed, reduced uranium bonded with aqueous silica in the ore zone to form coffinite. The high concentration of silica (as a monomeric species) in the ore-forming solution stabilized coffinite in preference to uraninite.-R.A.H.

XAFS and X-Ray and Electron Microscopy Investigations of Radionuclide Transformations at the Mineral-Microbe Interface

NASA Astrophysics Data System (ADS)

Kemner, Ken; O'Loughlin, Ed; Kelly, Shelly; Ravel, Bruce; Boyanov, Maxim; Sholto-Douglas, Deirdre; Lai, Barry; Cook, Russ; Carpenter, Everett; Harris, Vince; Nealson, Ken

2007-02-01

The microenvironment at and adjacent to surfaces of actively metabolizing cells, whether in a planktonic state or adhered to mineral surfaces, can be significantly different from the bulk environment. Microbial polymers (polysaccharides, DNA, RNA, and proteins), whether attached to or released from the cell, can contribute to the development of steep chemical gradients over very short distances. It is currently difficult to predict the behavior of contaminant radionuclides and metals in such microenvironments, because the chemistry there has been difficult or impossible to define. The behavior of contaminants in such microenvironments can ultimately affect their macroscopic fates. We have successfully performed a series of U LIII edge x-ray absorption fine structure (XAFS) spectroscopy, hard x-ray fluorescence (XRF) microprobe (150 nm resolution), and electron microscopy (EM) measurements on lepidocrocite thin films (˜1 micron thickness) deposited on kapton films that have been inoculated with the dissimilatory metal reducing bacterium Shewanella oneidensis MR-1 and exposed to 0.05 mM uranyl acetate under anoxic conditions. Similarly, we have performed a series of U LIII edge EXAFS measurements on lepidocrocite powders exposed to 0.05 mM uranyl acetate and exopolymeric components harvested from S. oneidensis MR-1 grown under aerobic conditions. These results demonstrate the utility of combining bulk XAFS with x-ray and electron microscopies.

Incorporation of Uranium into Hematite during Crystallization from Ferrihydrite

PubMed Central

2014-01-01

Ferrihydrite was exposed to U(VI)-containing cement leachate (pH 10.5) and aged to induce crystallization of hematite. A combination of chemical extractions, TEM, and XAS techniques provided the first evidence that adsorbed U(VI) (≈3000 ppm) was incorporated into hematite during ferrihydrite aggregation and the early stages of crystallization, with continued uptake occurring during hematite ripening. Analysis of EXAFS and XANES data indicated that the U(VI) was incorporated into a distorted, octahedrally coordinated site replacing Fe(III). Fitting of the EXAFS showed the uranyl bonds lengthened from 1.81 to 1.87 Å, in contrast to previous studies that have suggested that the uranyl bond is lost altogether upon incorporation into hematite. The results of this study both provide a new mechanistic understanding of uranium incorporation into hematite and define the nature of the bonding environment of uranium within the mineral structure. Immobilization of U(VI) by incorporation into hematite has clear and important implications for limiting uranium migration in natural and engineered environments. PMID:24580024

Phosphorus Sorption Capacity of Gray Forest Soil as Dependent on Fertilization System

NASA Astrophysics Data System (ADS)

Rogova, O. B.; Kolobova, N. A.; Ivanov, A. L.

2018-05-01

In this paper, the results of the study of changes in the phosphorus sorption capacity of gray forest soils of Vladimir opolie under the impact of different fertilization systems are discussed. The quantitative parameters of the potential buffer capacity of soils for phosphorus (PBCP) and Langmuir sorption isotherms have been calculated. It is shown that the application of organic fertilizers results in a stronger decrease in PBCP than the application of mineral fertilizers. The portion of phosphorus of mineral compounds considerably increases, and the high content of available phosphates is maintained. In the variants with application of mineral phosphorus in combination with manure, the portions of organic and mineral phosphorus are at the level typical of unfertilized soils. The energy of phosphate bonds with the soil is minimal upon the application of a double rate of mineral phosphorus at the maximum capacity in relation to phosphate ions.

Formic acid interaction with the uranyl(VI) ion: structural and photochemical characterization.

PubMed

Lucks, Christian; Rossberg, André; Tsushima, Satoru; Foerstendorf, Harald; Fahmy, Karim; Bernhard, Gert

2013-10-07

Complex formation between the uranyl(VI) ion and formic acid was studied by infrared absorption (IR) and X-ray absorption (EXAFS) spectroscopy as well as density functional theory (DFT) calculations. In contrast to the acetate ion which forms exclusively a bidentate complex with uranyl(VI), the formate ion binds to uranyl(VI) in a unidentate fashion. The photochemistry of the uranyl(VI)-formic acid system was explored by DFT calculations and photoreduction of uranyl(VI) in the presence of formic acid was found to occur via an intermolecular process, that is, hydrogen abstraction from hydrogenformate by the photo-excited uranyl(VI). There is no photo-induced decarboxylation of uranyl(VI) formate via an intramolecular process, presumably due to lack of a C=C double bond.

Influence of calcium, iron and pH on phosphate availability for microbial mineralization of organic chemicals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robertson, B.K.; Alexander, M.

1992-01-01

A study was conducted to determine some of the factors affecting the P requirement for the biodegradation of p-nitrophenol, phenol, and glucose by Pseudomonas and Corynebacterium strains. Mineralization of glucose was rapid and the Pseudomonas sp. grew extensively in solutions with 5 and 10 mM phosphate, but the rate and extent of degradation were low and the bacterial population never became abundant in media with 0.2 mM phosphate. Similar results were obtained with the Corynebacterium sp. growing in media containing p-nitrophenol or phenol and in solutions with a purified phosphate salt. The extent of growth of the Corynebacterium sp. wasmore » reduced with 2 or 10 mM phosphate in media containing high Fe concentrations. Ca at 5 mM but not 0.5 mM inhibited p-nitrophenol mineralization by the Corynebacterium sp. with phosphate concentrations from 0.2 to 5.0 mM. Phenol mineralization by the Pseudomonas sp. in medium with 0.2 mM phosphate was rapid at pH 5.2, but the bacteria had little or no activity at pH 8.0. In contrast, the activity was greater at pH 8.0 than at pH 5.2 when the culture contained 10 mM phosphate. These effects of pH were similar in media with 5 mM Ca or no added Ca. The authors conclude that the effect of P on bacterial degradation can be influenced by the pH and the concentrations of Fe and Ca.« less

Phosphorus availability and microbial immobilization in a Nitisol with the application of mineral and organo-mineral fertilizers.

PubMed

Morais, Francisco A; Gatiboni, Luciano C

2015-01-01

The aim of this study was to evaluate P availability, P and C contained in the microbial biomass, and enzymatic activity (acid phosphatases and β-glucosidases) in a Nitisol with the application of mineral and organo-mineral fertilizers. The experiment was performed in a protected environment with control over air temperature and soil moisture. The experimental design was organized in a "5 x 4" factorial arrangement with five sources of P and four times of soil incubation. The sources were: control (without P), triple superphosphate, diammonium phosphate, natural Arad reactive rock phosphate, and organo-mineral fertilizer. The experimental units consisted of PVC columns filled with agricultural soil. The columns were incubated and broken down for analysis at 1, 20, 40, and 60 days after application of the fertilizers. In each column, samples were taken at the layers of 0-2.5, 2.5-5.0, and 5.0-15.0 cm below the zone of the fertilizers. The application of soluble phosphates and organo-mineral fertilizer temporarily increased P availability in the zone near the fertilizers (0-2.5 cm), with maximum availability occurring at approximately 32 days. Microbial immobilization showed behavior similar to P availability, and the greatest immobilizations occurred at approximately 30 days. The organo-mineral fertilizer was not different from soluble phosphates.

Vibrational spectroscopy of synthetic stercorite H(NH 4)Na(PO 4)·4H 2O—A comparison with the natural cave mineral

NASA Astrophysics Data System (ADS)

Frost, Ray L.; Xi, Yunfei; Palmer, Sara J.; Millar, Graeme J.; Tan, Keqin; Pogson, Ross E.

2011-12-01

In order to mimic the chemical reactions in cave systems, the analogue of the mineral stercorite H(NH 4)Na(PO 4)·4H 2O has been synthesised. X-ray diffraction of the stercorite analogue matches the stercorite reference pattern. A comparison is made with the vibrational spectra of synthetic stercorite analogue and the natural Cave mineral. The mineral in nature is formed by the reaction of bat guano chemicals on calcite substrates. A single Raman band at 920 cm -1 (Cave) and 922 cm -1 (synthesised) defines the presence of hydrogen phosphate in the mineral. In the synthetic stercorite analogue, additional bands are observed and are attributed to the dihydrogen and phosphate anions. The vibrational spectra of synthetic stercorite only partly match that of the natural stercorite. It is suggested that natural stercorite is more pure than that of synthesised stercorite. Antisymmetric stretching bands are observed in the infrared spectrum at 1052, 1097, 1135 and 1173 cm -1. Raman spectroscopy shows the stercorite mineral is based upon the hydrogen phosphate anion and not the phosphate anion. Raman and infrared bands are found and assigned to PO 43-, H 2O, OH and NH stretching vibrations. Raman spectroscopy shows the synthetic analogue is similar to the natural mineral. A mechanism for the formation of stercorite is provided.

Construction of the Syngonium podophyllum-Pseudomonas sp. XNN8 Symbiotic Purification System and Investigation of Its Capability of Remediating Uranium Wastewater.

PubMed

Deng, Qin-Wen; Wang, Yong-Dong; Ding, De-Xin; Hu, Nan; Sun, Jing; He, Jia-Dong; Xu, Fei

2017-02-01

The endophyte Pseudomonas sp. XNN8 was separated from Typha orientalis which can secrete indole-3-acetic acid and 1-aminocyclopropane-1-carboxylate deaminase and siderophores and has strong resistance to uranium it was then colonized in the Syngonium podophyllum; and the S. podophyllum-Pseudomonas sp. XNN8 symbiotic purification system (SPPSPS) for uranium-containing wastewater was constructed. Afterwards, the hydroponic experiments to remove uranium from uranium-containing wastewater by the SPPSPS were conducted. After 24 days of treatment, the uranium concentrations of the wastewater samples with uranium concentrations between 0.5 and 5.0 mg/L were lowered to below 0.05 mg/L. Furthermore, the uranium in the plants was assayed using Fourier transform infrared spectroscopy (FTIR) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The Pseudomonas sp. XNN8 was found to generate substantial organic groups in the roots of the Syngonium podophyllum, which could improve the complexing capability of S. podophyllum for uranium. The uranium in the roots of S. podophyllum was found to be the uranyl phosphate (47.4 %) and uranyl acetate (52.6 %).

Spatially and temporally controlled biomineralization is facilitated by interaction between self-assembled dentin matrix protein 1 and calcium phosphate nuclei in solution.

PubMed

He, Gen; Gajjeraman, Sivakumar; Schultz, David; Cookson, David; Qin, Chunlin; Butler, William T; Hao, Jianjun; George, Anne

2005-12-13

Bone and dentin biomineralization are well-regulated processes mediated by extracellular matrix proteins. It is widely believed that specific matrix proteins in these tissues modulate nucleation of apatite nanoparticles and their growth into micrometer-sized crystals via molecular recognition at the protein-mineral interface. However, this assumption has been supported only circumstantially, and the exact mechanism remains unknown. Dentin matrix protein 1 (DMP1) is an acidic matrix protein, present in the mineralized matrix of bone and dentin. In this study, we have demonstrated using synchrotron small-angle X-ray scattering that DMP1 in solution can undergo oligomerization and temporarily stabilize the newly formed calcium phosphate nanoparticle precursors by sequestering them and preventing their further aggregation and precipitation. The solution structure represents the first low-resolution structural information for DMP1. Atomic force microscopy and transmission electron microscopy studies further confirmed that the nascent calcium phosphate nuclei formed in solution were assembled into ordered protein-mineral complexes with the aid of oligomerized DMP1, recombinant and native. This study reveals a novel mechanism by which DMP1 might facilitate initiation of mineral nucleation at specific sites during bone and dentin mineralization and prevent spontaneous calcium phosphate precipitation in areas in which mineralization is not desirable.

The role of intracellular calcium phosphate in osteoblast-mediated bone apatite formation

PubMed Central

Boonrungsiman, Suwimon; Gentleman, Eileen; Carzaniga, Raffaella; Evans, Nicholas D.; McComb, David W.; Porter, Alexandra E.; Stevens, Molly M.

2012-01-01

Mineralization is a ubiquitous process in the animal kingdom and is fundamental to human development and health. Dysfunctional or aberrant mineralization leads to a variety of medical problems, and so an understanding of these processes is essential to their mitigation. Osteoblasts create the nano-composite structure of bone by secreting a collagenous extracellular matrix (ECM) on which apatite crystals subsequently form. However, despite their requisite function in building bone and decades of observations describing intracellular calcium phosphate, the precise role osteoblasts play in mediating bone apatite formation remains largely unknown. To better understand the relationship between intracellular and extracellular mineralization, we combined a sample-preparation method that simultaneously preserved mineral, ions, and ECM with nano-analytical electron microscopy techniques to examine osteoblasts in an in vitro model of bone formation. We identified calcium phosphate both within osteoblast mitochondrial granules and intracellular vesicles that transported material to the ECM. Moreover, we observed calcium-containing vesicles conjoining mitochondria, which also contained calcium, suggesting a storage and transport mechanism. Our observations further highlight the important relationship between intracellular calcium phosphate in osteoblasts and their role in mineralizing the ECM. These observations may have important implications in deciphering both how normal bone forms and in understanding pathological mineralization. PMID:22879397

Paracrystalline Disorder from Phosphate Ion Orientation and Substitution in Synthetic Bone Mineral

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marisa, Mary E.; Zhou, Shiliang; Melot, Brent C.

Hydroxyapatite is an inorganic mineral closely resembling the mineral phase in bone. However, as a biological mineral, it is highly disordered, and its composition and atomistic structure remain poorly understood. Here, synchrotron X-ray total scattering and pair distribution function analysis methods provide insight into the nature of atomistic disorder in a synthetic bone mineral analogue, chemically substituted hydroxyapatite. By varying the effective hydrolysis rate and/or carbonate concentration during growth of the mineral, compounds with varied degrees of paracrystallinity are prepared. From advanced simulations constrained by the experimental pair distribution function and density functional theory, the paracrystalline disorder prevalent in thesemore » materials appears to result from accommodation of carbonate in the lattice through random displacement of the phosphate groups. Though many substitution modalities are likely to occur in concert, the most predominant substitution places carbonate into the mirror plane of an ideal phosphate site. Understanding the mineralogical imperfections of a biologically analogous hydroxyapatite is important not only to potential bone grafting applications but also to biological mineralization processes themselves.« less

Effect of Phosphate on U(VI) Sorption to Montmorillonite: Ternary Complexation and Precipitation Barriers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Troyer, Lyndsay D.; Maillot, Fabien; Wang, Zheming

Phosphate addition is a potential treatment method to lower the solubility of U(VI) in soil and groundwater systems by causing U(VI) phosphate precipitation as well as enhancing adsorption. Previous work has shown that iron oxide surfaces may facilitate the nucleation of U(VI) phosphate minerals and, that under weakly acidic conditions, phosphate also enhances U(VI) adsorption to such phases. Like iron oxides, clays are important reactive phases in the subsurface but little is known about the interaction of U(VI) and phosphate with these minerals. The effect of aqueous phosphate on U(VI) binding to Wyoming montmorillonite (SWy-2) in air-equilibrated systems was investigated.more » Equilibrium U(VI) uptake to montmorillonite was determined at pH 4, 6 and 8 at discrete initial phosphate concentrations between 0 and 100 μM. The observed behavior of U(VI) indicates a transition from adsorption to precipitation with increasing total uranium and phosphate concentrations at all pH values. At the highest phosphate concentration examined at each pH value, a barrier to U(VI) phosphate nucleation is observed. At lower concentrations, phosphate has no effect on macroscopic U(VI) adsorption. To assess the mechanisms of U(VI)-phosphate interactions on smectite surfaces, U(VI) speciation was investigated under selected conditions using laser-induced fluorescence spectroscopy (LIFS) and extended X-ray absorption fine-structure (EXAFS) spectroscopy. Samples above the precipitation threshold display EXAFS and LIFS spectral signatures consistent with the autunite family of U(VI) phosphate minerals. However, at lower U(VI) concentrations, changes in LIFS spectra upon phosphate addition suggest that U(VI)-phosphate ternary surface complexes form on the montmorillonite surface at pH 4 and 6 despite the lack of a macroscopic effect on adsorption. The speciation of solid-associated U(VI) below the precipitation threshold at pH 8 is dominated by U(VI)-carbonate surface complexes. This work reveals that ternary complexation may occur without a macroscopic signature, which is attributed to phosphate not appreciably binding to smectite in the absence of U(VI), with U(VI) surface complexes serving as the sole reactive surface sites for phosphate. This study shows that phosphate does not enhance U(VI) adsorption to smectite clay minerals, unlike oxide phases, and that a barrier to homogeneous nucleation of U(VI) phosphates was not affected by the presence of the smectite surface« less

Skeletal secretion of FGF-23 regulates phosphate and vitamin D metabolism

PubMed Central

Quarles, L. Darryl

2014-01-01

The discovery of fibroblast growth factor 23 (FGF-23) has expanded our understanding of phosphate and vitamin D homeostasis and provided new insights into the pathogenesis of hereditary hypophosphatemic and hyperphosphatemic disorders, as well as acquired disorders of phosphate metabolism, such as chronic kidney disease. FGF-23 is secreted by osteoblasts and osteocytes in bone and principally targets the kidney to regulate the reabsorption of phosphate, the production and catabolism of 1,25-dihydroxyvitamin D and the expression of α-Klotho, an anti-ageing hormone. Secreted FGF-23 plays a central role in complex endocrine networks involving local bone-derived factors that regulate mineralization of extracellular matrix and systemic hormones involved in mineral metabolism. Inactivating mutations of PHEX, DMP1 and ENPP1, which cause hereditary hypophosphatemic disorders and primary defects in bone mineralization, stimulate FGF23 gene transcription in osteoblasts and osteocytes, at least in part, through canonical and intracrine FGF receptor pathways. These FGF-23 regulatory pathways may enable systemic phosphate and vitamin D homeostasis to be coordinated with bone mineralization. FGF-23 also functions as a counter-regulatory hormone for 1,25-dihydroxyvitamin D in a bone–kidney endocrine loop. FGF-23, through regulation of additional genes in the kidney and extrarenal tissues, probably has broader physiological functions beyond regulation of mineral metabolism that account for the association between FGF-23 and increased mortality and morbidity in chronic kidney disease. PMID:22249518

An infrared and Raman spectroscopic study of natural zinc phosphates.

PubMed

Frost, Ray L

2004-06-01

Zinc phosphates are important in the study of the phosphatisation of metals. Raman spectroscopy in combination with infrared spectroscopy has been used to characterise the zinc phosphate minerals. The minerals may be characterised by the patterns of the hydroxyl stretching vibrations in both the Raman and infrared spectra. Spencerite is characterised by a sharp Raman band at 3516 cm(-1) and tarbuttite by a single band at 3446 cm(-1). The patterns of the Raman spectra of the hydroxyl stretching region of hopeite and parahopeite are different in line with their differing crystal structures. The Raman spectrum of the PO4 stretching region shows better band separated peaks than the infrared spectra which consist of a complex set of overlapping bands. The position of the PO4 symmetric stretching mode can be used to identify the zinc phosphate mineral. It is apparent that Raman spectroscopy lends itself to the fundamental study of the evolution of zinc phosphate films.

Coating electrospun poly(epsilon-caprolactone) fibers with gelatin and calcium phosphate and their use as biomimetic scaffolds for bone tissue engineering.

PubMed

Li, Xiaoran; Xie, Jingwei; Yuan, Xiaoyan; Xia, Younan

2008-12-16

Electrospinning was employed to fabricate fibrous scaffolds of poly(epsilon-caprolactone) in the form of nonwoven mats. The surfaces of the fibers were then coated with gelatin through layer-by-layer self-assembly, followed by functionalization with a uniform coating of bonelike calcium phosphate by mineralization in the 10 times concentrated simulated body fluid for 2 h. Transmission electron microscopy, water contact angle, and scanning electron microscopy measurements confirmed the presence of gelatin and calcium phosphate coating layers, and X-ray diffraction results suggested that the deposited mineral phase was a mixture of dicalcium phosphate dehydrate (a precursor to apatite) and apatite. It was also demonstrated that the incorporation of gelatin promoted nucleation and growth of calcium phosphate. The porous scaffolds could mimic the structure, composition, and biological function of bone extracellular matrix. It was found that the preosteoblastic MC3T3-E1 cells attached, spread, and proliferated well with a flat morphology on the mineralized scaffolds. The proliferation rate of the cells on the mineralized scaffolds was significantly higher (by 1.9-fold) than that on the pristine fibrous scaffolds after culture for 7 days. These results indicated that the hybrid system containing poly(epsilon-caprolactone), gelatin, and calcium phosphate could serve as a new class of biomimetic scaffolds for bone tissue engineering.

Mineralized agar-based nanocomposite films: Potential food packaging materials with antimicrobial properties.

PubMed

Malagurski, Ivana; Levic, Steva; Nesic, Aleksandra; Mitric, Miodrag; Pavlovic, Vladimir; Dimitrijevic-Brankovic, Suzana

2017-11-01

New mineralized, agar-based nanocomposite films (Zn-carbonate and Zn-phosphate/agar) were produced by a combination of in situ precipitation and a casting method. The presence of minerals significantly influenced the morphology, properties and functionality of the obtained nanocomposites. Reinforcement with the Zn-mineral phase improved the mechanical properties of the carbonate-mineralized films, but had a negligible effect on the phosphate-mineralized samples. Both nanocomposites showed improved optical and thermal properties, better Zn(II) release potential in a slightly acidic environment and exhibited antimicrobial activity against S. aureus. These results suggest that Zn-mineralized agar nanocomposite films could be potentially used as affordable, eco-friendly and active food packaging materials. Copyright © 2017 Elsevier Ltd. All rights reserved.

Photochemical water oxidation and origin of nonaqueous uranyl peroxide complexes.

PubMed

McGrail, Brendan T; Pianowski, Laura S; Burns, Peter C

2014-04-02

Sunlight photolysis of uranyl nitrate and uranyl acetate solutions in pyridine produces uranyl peroxide complexes. To answer longstanding questions about the origin of these complexes, we conducted a series of mechanistic studies and demonstrate that these complexes arise from photochemical oxidation of water. The peroxo ligands are easily removed by protonolysis, allowing regeneration of the initial uranyl complexes for potential use in catalysis.

Supramolecular structure of the casein micelle.

PubMed

McMahon, D J; Oommen, B S

2008-05-01

The supramolecular structure of colloidal casein micelles in milk was investigated by using a sample preparation protocol based on adsorption of proteins onto a poly-l-lysine and parlodion-coated copper grid, staining of proteins and calcium phosphate by uranyl oxalate, instantaneous freezing, and drying under a high vacuum. High-resolution transmission electron microscopy stereo-images were obtained showing the interior structure of casein micelles. On the basis of our interpretation of these images, an interlocked lattice model was developed in which both casein-calcium phosphate aggregates and casein polymer chains act together to maintain casein micelle integrity. The caseins form linear and branched chains (2 to 5 proteins long) interlocked by the casein-stabilized calcium phosphate nanoclusters. This model suggests that stabilization of calcium phosphate nanoclusters by phosphoserine domains of alpha(s1)-, alpha(s2)-, or beta-casein, or their combination, would orient their hydrophobic domains outward, allowing interaction and binding to other casein molecules. Other interactions between the caseins, such as calcium bridging, could also occur and further stabilize the supramolecule. The combination of having an interlocked lattice structure and multiple interactions results in an open, sponge-like colloidal supramolecule that is resistant to spatial changes and disintegration. Hydrophobic interactions between caseins surrounding a calcium phosphate nanocluster would prevent complete dissociation of casein micelles when the calcium phosphate nanoclusters are solubilized. Likewise, calcium bridging and other electrostatic interactions between caseins would prevent dissociation of the casein micelles into casein-calcium phosphate nanocluster aggregates when milk is cooled or urea is added to milk, and hydrophobic interactions are reduced. The appearance of both polymer chains and small aggregate particles during milk synthesis would also be expected based on this interlocked lattice model of casein micelles, and its supramolecule structure thus exhibits the principles of self-aggregation, interdependence, and diversity observed in nature.

Confocal laser Raman microspectroscopy of biomineralization foci in UMR 106 osteoblastic cultures reveals temporally synchronized protein changes preceding and accompanying mineral crystal deposition.

PubMed

Wang, Chuanyi; Wang, Yong; Huffman, Nichole T; Cui, Chaoying; Yao, Xiaomei; Midura, Sharon; Midura, Ronald J; Gorski, Jeff P

2009-03-13

Mineralization in UMR 106-01 osteoblastic cultures occurs within extracellular biomineralization foci (BMF) within 12 h after addition of beta-glycerol phosphate to cells at 64 h after plating. BMF are identified by their enrichment with an 85-kDa glycoprotein reactive with Maackia amurensis lectin. Laser Raman microspectroscopic scans were made on individual BMF at times preceding (64-76 h) and following the appearance of mineral crystals (76-88 h). The range of variation between spectra for different BMF in the same culture was rather small. In contrast, significant differences were observed for spectral bands at 957-960, 1004, and 1660 cm(-1) when normalized BMF spectra at different times were compared. Protein-dependent spectral bands at 1004 and 1660 cm(-1) increased and then decreased preceding the detection of hydroxyapatite crystals via the phosphate stretching peak at 959-960 cm(-1). When sodium phosphate was substituted for beta-glycerol phosphate, mineralization occurred 3-6 h earlier. Irrespective of phosphate source, the Raman full peak width at half-maximum ratio for 88 h cultures was similar to that for 10-day-old marrow ablation primary bone. However, if mineralization was blocked with serine protease inhibitor 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride, 64-88-h BMF spectra remained largely invariant. In summary, Raman spectral data demonstrate for the first time that formation of hydroxyapatite crystals within individual BMF is a multistep process. Second, changes in protein-derived signals at 1004 and 1660 cm(-1) reflect events within BMFs that precede or accompany mineral crystal production because they are blocked by mineralization inhibitor 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride. Finally, the low extent of spectral variability detected among different BMF at the same time point indicates that mineralization of individual BMF within a culture is synchronized.

Confocal Laser Raman Microspectroscopy of Biomineralization Foci in UMR 106 Osteoblastic Cultures Reveals Temporally Synchronized Protein Changes Preceding and Accompanying Mineral Crystal Deposition*

PubMed Central

Wang, Chuanyi; Wang, Yong; Huffman, Nichole T.; Cui, Chaoying; Yao, Xiaomei; Midura, Sharon; Midura, Ronald J.; Gorski, Jeff P.

2009-01-01

Mineralization in UMR 106-01 osteoblastic cultures occurs within extracellular biomineralization foci (BMF) within 12 h after addition of β-glycerol phosphate to cells at 64 h after plating. BMF are identified by their enrichment with an 85-kDa glycoprotein reactive with Maackia amurensis lectin. Laser Raman microspectroscopic scans were made on individual BMF at times preceding (64–76 h) and following the appearance of mineral crystals (76–88 h). The range of variation between spectra for different BMF in the same culture was rather small. In contrast, significant differences were observed for spectral bands at 957–960, 1004, and 1660 cm-1 when normalized BMF spectra at different times were compared. Protein-dependent spectral bands at 1004 and 1660 cm-1 increased and then decreased preceding the detection of hydroxyapatite crystals via the phosphate stretching peak at 959–960 cm-1. When sodium phosphate was substituted for β-glycerol phosphate, mineralization occurred 3–6 h earlier. Irrespective of phosphate source, the Raman full peak width at half-maximum ratio for 88 h cultures was similar to that for 10-day-old marrow ablation primary bone. However, if mineralization was blocked with serine protease inhibitor 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride, 64–88-h BMF spectra remained largely invariant. In summary, Raman spectral data demonstrate for the first time that formation of hydroxyapatite crystals within individual BMF is a multistep process. Second, changes in protein-derived signals at 1004 and 1660 cm-1 reflect events within BMFs that precede or accompany mineral crystal production because they are blocked by mineralization inhibitor 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride. Finally, the low extent of spectral variability detected among different BMF at the same time point indicates that mineralization of individual BMF within a culture is synchronized. PMID:19116206

Partitioning of uranyl between ferrihydrite and humic substances at acidic and circum-neutral pH

NASA Astrophysics Data System (ADS)

Dublet, Gabrielle; Lezama Pacheco, Juan; Bargar, John R.; Fendorf, Scott; Kumar, Naresh; Lowry, Gregory V.; Brown, Gordon E.

2017-10-01

As part of a larger study of the reactivity and mobility of uranyl (U(VI)O22+) cations in subsurface environments containing natural organic matter (NOM) and hydrous ferric oxides, we have examined the effect of reference humic and fulvic substances on the sorption of uranyl on 2-line ferrihydrite (Fh), a common, naturally occurring nano-Fe(III)-hydroxide. Uranyl was reacted with Fh at pH 4.6 and 7.0 in the presence and absence of Elliott Soil Humic Acid (ESHA) (0-835 ppm) or Suwanee River Fulvic Acid (SRFA) (0-955 ppm). No evidence was found for reduction of uranyl by either form of NOM after 24 h of exposure. The following three size fractions were considered in this study: (1) ≥0.2 μm (Fh-NOM aggregates), (2) 0.02-0.2 μm (dispersed Fh nanoparticles and NOM macro-molecules), and (3) <0.02 μm (dissolved). The extent to which U(VI) is sorbed in aggregates or dispersed as colloids was assessed by comparing U, Fe, and NOM concentrations in these three size fractions. Partitioning of uranyl between Fh and NOM was determined in size fraction (1) using X-ray absorption spectroscopy (XAS). Uranyl sorption on Fh-NOM aggregates was affected by the presence of NOM in different ways depending on pH and type of NOM (ESHA vs. SRFA). The presence of ESHA in the uranyl-Fh-NOM ternary system at pH 4.6 enhanced uranyl uptake more than the presence of SRFA. In contrast, neither form of NOM affected uranyl sorption at pH 7.0 over most of the NOM concentration range examined (0-500 ppm); at the highest NOM concentrations (500-955 ppm) uranyl uptake in the aggregates was slightly inhibited at pH 7.0, which is interpreted as being due to the dispersion of Fh aggregates. XAS at the U LIII-edge was used to characterize molecular-level changes in uranyl complexation as a result of sorption to the Fh-NOM aggregates. In the absence of NOM, uranyl formed dominantly inner-sphere, mononuclear, bidentate sorption complexes on Fh. However, when NOM concentration was increased at pH 4.6, the proportion of uranyl-Fh inner-sphere sorption complexes decreased relative to uranyl-ESHA or uranyl-SRFA complexes, which comprised up to ∼60% of the total uranyl in the systems studied. At pH 7.0, uranyl-NOM complexes were also present in the Fh-NOM aggregates in the concentration ranges of ESHA or SRFA considered; however, the proportion of these complexes was smaller at pH 7.0 than at pH 4.6 and did not increase significantly with increasing NOM concentration.

Combination of solid phase extraction and dispersive liquid-liquid microextraction for separation/preconcentration of ultra trace amounts of uranium prior to its fiber optic-linear array spectrophotometry determination.

PubMed

Dadfarnia, Shayessteh; Shabani, Ali Mohammad Haji; Shakerian, Farid; Shiralian Esfahani, Golnaz

2013-12-15

A simple and sensitive method for the separation and preconcentration of the ultra trace amounts of uranium and its determination by spectrophotometry was developed. The method is based on the combination of solid phase extraction and dispersive liquid-liquid microextraction. Thus, by passing the sample through the basic alumina column, the uranyl ion and some cations are separated from the sample matrix. The retained uranyl ion along with the cations are eluted with 5 mL of nitric acid (2 mol L(-1)) and after neutralization of the eluent, the extracted uranyl ion is converted to its anionic benzoate complex and is separated from other cations by extraction of its ion pair with malachite green into small volume of chloroform using dispersive liquid-liquid microextraction. The amount of uranium is then determined by the absorption measurement of the extracted ion pair at 621 nm using flow injection spectrophotometry. Under the optimum conditions, with 500 mL of the sample, a preconcentration factor of 1980, a detection limit of 40 ng L(-1), and a relative standard deviation of 4.1% (n=6) at 400 ng L(-1) were obtained. The method was successfully applied to the determination of uranium in mineral water, river water, well water, spring water and sea water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Variations in the uranium isotopic compositions of uranium ores from different types of uranium deposits

NASA Astrophysics Data System (ADS)

Uvarova, Yulia A.; Kyser, T. Kurt; Geagea, Majdi Lahd; Chipley, Don

2014-12-01

Variations in 238U/235U and 234U/238U ratios were measured in uranium minerals from a spectrum of uranium deposit types, as well as diagenetic phosphates in uranium-rich basins and peraluminous rhyolites and associated autunite mineralisation from Macusani Meseta, Peru. Mean δ238U values of uranium minerals relative to NBL CRM 112-A are 0.02‰ for metasomatic deposits, 0.16‰ for intrusive, 0.18‰ for calcrete, 0.18‰ for volcanic, 0.29‰ for quartz-pebble conglomerate, 0.29‰ for sandstone-hosted, 0.44‰ for unconformity-type, and 0.56‰ for vein, with a total range in δ238U values from -0.30‰ to 1.52‰. Uranium mineralisation associated with igneous systems, including low-temperature calcretes that are sourced from U-rich minerals in igneous systems, have low δ238U values of ca. 0.1‰, near those of their igneous sources, whereas uranium minerals in basin-hosted deposits have higher and more variable values. High-grade unconformity-related deposits have δ238U values around 0.2‰, whereas lower grade unconformity-type deposits in the Athabasca, Kombolgie and Otish basins have higher δ238U values. The δ234U values for most samples are around 0‰, in secular equilibrium, but some samples have δ234U values much lower or higher than 0‰ associated with addition or removal of 234U during the past 2.5 Ma. These δ238U and δ234U values suggest that there are at least two different mechanisms responsible for 238U/235U and 234U/238U variations. The 234U/238U disequilibria ratios indicate recent fluid interaction with the uranium minerals and preferential migration of 234U. Fractionation between 235U and 238U is a result of nuclear-field effects with enrichment of 238U in the reduced insoluble species (mostly UO2) and 235U in oxidised mobile species as uranyl ion, UO22+, and its complexes. Therefore, isotopic fractionation effects should be reflected in 238U/235U ratios in uranium ore minerals formed either by reduction of uranium to UO2 or chemical precipitation in the form of U6+ minerals. The δ238U values of uranium ore minerals from a variety of deposits are controlled by the isotopic signature of the uranium source, the efficiency of uranium reduction in the case of UO2 systems, and the degree to which uranium was previously removed from the fluid, with less influence from temperature of ore formation and later alteration of the ore. Uranium isotopes are potentially superb tracers of redox in natural systems.

Low-intensity pulsed ultrasound (LIPUS) stimulates mineralization of MC3T3-E1 cells through calcium and phosphate uptake.

PubMed

Tassinary, João Alberto Fioravante; Lunardelli, Adroaldo; Basso, Bruno de Souza; Dias, Henrique Bregolin; Catarina, Anderson Velasque; Stülp, Simone; Haute, Gabriela Viegas; Martha, Bianca Andrade; Melo, Denizar Alberto da Silva; Nunes, Fernanda Bordignon; Donadio, Márcio Vinícius Fagundes; Oliveira, Jarbas Rodrigues de

2018-03-01

The present study aimed to evaluate the effect of low-intensity pulsed ultrasound (LIPUS) on pre-osteoblast mineralization using in vitro bioassays. Pre-osteoblastic MC3T3-E1 cells were exposed to LIPUS at 1 MHz frequency, 0.2 W/cm 2 intensity and 20% duty cycle for 30 min. The analyses were carried out up to 336 h (14 days) after exposure. The concentration of collagen, phosphate, alkaline phosphatase, calcium and transforming growth factor beta 1 (TGF-β1) in cell supernatant and the presence of calcium deposits in the cells were analyzed. Our results showed that LIPUS promotes mineralized nodules formation. Collagen, phosphate, and calcium levels were decreased in cell supernatant at 192 h after LIPUS exposure. However, alkaline phosphatase and TGF-β1 concentrations remained unchanged. Therapeutic pulsed ultrasound is capable of stimulating differentiation and mineralization of pre-osteoblastic MC3T3-E1 cells by calcium and phosphate uptake with consequent hydroxyapatite formation. Copyright © 2017 Elsevier B.V. All rights reserved.

Incorporation mechanisms of actinide elements into the structures of U 6+ phases formed during the oxidation of spent nuclear fuel

NASA Astrophysics Data System (ADS)

Burns, Peter C.; Ewing, Rodney C.; Miller, Mark L.

1997-05-01

Uranyl oxide hydrate and uranyl silicate phases will form due to the corrosion and alteration of spent nuclear fuel under oxidizing conditions in silica-bearing solution. The actinide elements in the spent fuel may be incorporated into the structures of these secondary U6+ phases during the long-term corrosion of the UO 2 in spent fuel. The incorporation of actinide elements into the crystal structures of the alteration products may decrease actinide mobility. The crystal chemistry of the various oxidation states of the actinide elements of environmental concern is examined to identify possible incorporation mechanisms. The substitutions Pu 6+U 6+ and (Pu 5+, Np 5+)U 6+ should readily occur in many U 6+ structures, although structural modification may be required to satisfy local bond-valence requirements. Crystal-chemical characteristics of the U 6+ phases indicate that An 4+ (An: actinide)U 6+ substitution is likely to occur in the sheets of uranyl polyhedra that occur in the structures of the minerals schoepite, [(UO 2) 8O 2(OH) 12](H 2O) 12, ianthinite, [U 24+ (UO 2) 4O 6(OH) 4(H 2O) 4](H 2O) 5, becquerelite, Ca[(UO 2) 3O 2(OH) 3] 2(H 2O) 8, compreignacite, K 2[(UO 2) 3O 2(OH) 3] 2(H 2O) 8, α-uranophane, Ca[(UO 2)(SiO 3OH)] 2(H 2O) 5, and boltwoodite, K(H 2O)[(UO 2)(SiO 4)], all of which are likely to form due to the oxidation and alteration of the UO 2 in spent fuel. The incorporation of An 3+ into the sheets of the structures of α-uranophane and boltwoodite, as well as interlayer sites of various uranyl phases, may occur.

Homozygous ablation of fibroblast growth factor-23 results in hyperphosphatemia and impaired skeletogenesis, and reverses hypophosphatemia in Phex-deficient mice.

PubMed

Sitara, Despina; Razzaque, Mohammed S; Hesse, Martina; Yoganathan, Subbiah; Taguchi, Takashi; Erben, Reinhold G; Jüppner, Harald; Lanske, Beate

2004-11-01

Fibroblast growth factor-23 (FGF-23), a recently identified molecule that is mutated in patients with autosomal dominant hypophosphatemic rickets (ADHR), appears to be involved in the regulation of phosphate homeostasis. Although increased levels of circulating FGF-23 were detected in patients with different phosphate-wasting disorders such as oncogenic osteomalacia (OOM) and X-linked hypophosphatemia (XLH), it is not yet clear whether FGF-23 is directly responsible for the abnormal regulation of mineral ion homeostasis and consequently bone development. To address some of these unresolved questions, we generated a mouse model, in which the entire Fgf-23 gene was replaced with the lacZ gene. Fgf-23 null (Fgf-23-/-) mice showed signs of growth retardation by day 17, developed severe hyperphosphatemia with elevated serum 1,25(OH)2D3 levels, and died by 13 weeks of age. Hyperphosphatemia in Fgf-23-/- mice was accompanied by skeletal abnormalities, as demonstrated by histological, molecular, and various other morphometric analyses. Fgf-23-/-) mice had increased total-body bone mineral content (BMC) but decreased bone mineral density (BMD) of the limbs. Overall, Fgf-23-/- mice exhibited increased mineralization, but also accumulation of unmineralized osteoid leading to marked limb deformities. Moreover, Fgf-23-/- mice showed excessive mineralization in soft tissues, including heart and kidney. To further expand our understanding regarding the role of Fgf-23 in phosphate homeostasis and skeletal mineralization, we crossed Fgf-23-/- animals with Hyp mice, the murine equivalent of XLH. Interestingly, Hyp males lacking both Fgf-23 alleles were indistinguishable from Fgf-23/-/ mice, both in terms of serum phosphate levels and skeletal changes, suggesting that Fgf-23 is upstream of the phosphate regulating gene with homologies to endopeptidases on the X chromosome (Phex) and that the increased plasma Fgf-23 levels in Hyp mice (and in XLH patients) may be at least partially responsible for the phosphate imbalance in this disorder.

Structural, mechanical and vibrational study of uranyl silicate mineral soddyite by DFT calculations

NASA Astrophysics Data System (ADS)

Colmenero, Francisco; Bonales, Laura J.; Cobos, Joaquín; Timón, Vicente

2017-09-01

Uranyl silicate mineral soddyite, (UO2)2(SiO4)·2(H2O), is a fundamental component of the paragenetic sequence of secondary phases that arises from the weathering of uraninite ore deposits and corrosion of spent nuclear fuel. In this work, soddyite was studied by first principle calculations based on the density functional theory. As far as we know, this is the first time that soddyite structure is determined theoretically. The computed structure of soddyite reproduces the one determined experimentally by X-Ray diffraction (orthorhombic symmetry, spatial group Fddd O2; lattice parameters a = 8.334 Å, b = 11.212 Å; c = 18.668 Å). Lattice parameters, bond lengths, bond angles and X-Ray powder pattern were found to be in very good agreement with their experimental counterparts. Furthermore, the mechanical properties were obtained and the satisfaction of the Born conditions for mechanical stability of the structure was demonstrated by means of calculations of the elasticity tensor. The equation of state of soddyite was obtained by fitting lattice volumes and pressures to a fourth order Birch-Murnahan equation of state. The Raman spectrum was also computed by means of density functional perturbation theory and compared with the experimental spectrum obtained from a natural soddyite sample. The results were also found in agreement with the experimental data. A normal mode analysis of the theoretical spectra was carried out and used in order to assign the main bands of the Raman spectrum.

Uranyl ion coordination

USGS Publications Warehouse

Evans, H.T.

1963-01-01

A review of the known crystal structures containing the uranyl ion shows that plane-pentagon coordination is equally as prevalent as plane-square or plane-hexagon. It is suggested that puckered-hexagon configurations of OH - or H2O about the uranyl group will tend to revert to plane-pentagon coordination. The concept of pentagonal coordination is invoked for possible explanations of the complex crystallography of the natural uranyl hydroxides and the unusual behavior of polynuclear ions in hydrolyzed uranyl solutions.

Influence of long-term fertilization on soil physicochemical properties in a brown soil

NASA Astrophysics Data System (ADS)

Li, Dongdong; Luo, Peiyu; Han, Xiaori; Yang, Jinfeng

2018-01-01

This study aims to explore the influence on soil physicochemical properties under a 38-y long-term fertilization in a brown soil. Soil samples (0-20 cm)were taken from the six treatments of the long-term fertilization trial in October 2016:no fertilizer (CK), N1(mineral nitrogen fertilizer), N1P (mineral nitrogen and phosphate fertilizer), N1PK (mineral nitrogen, phosphate and potassic fertilizer), pig manure (M2), M2N1P (pig manure, mineral nitrogen and phosphate fertilizer).The results showed thatthe long-term application of chemical fertilizers reduced soil pH value, while the application of organic fertilizers increased pH value. Fertilization significantly increased the content of AHN, TN and SOM. Compared with the CK treatment and chemical fertilizer treatments, organic fertilizer treatments significantly increased the content of AP and TP. The content of AK and TK were no significant difference in different treatment.

Fe(III) reduction-mediated phosphate removal as vivianite (Fe3(PO4)2⋅8H2O) in septic system wastewater.

PubMed

Azam, Hossain M; Finneran, Kevin T

2014-02-01

Phosphate is a water contaminant from fertilizers, soaps, and detergents that enters municipal and onsite wastewater from households, businesses, and other commercial operations. Phosphate is a limiting nutrient for algae, and is one of the molecules that promotes eutrophication of water bodies. Phosphate is especially problematic in onsite wastewater because there are few removal mechanisms under normal operating conditions; a system must be amended specifically with compounds to bond to or adsorb phosphate in the septic tank or within the leach field. Vivianite (Fe3(PO4)2⋅8H2O) is a stable mineral formed from ferrous iron and phosphate, often as the result of Fe(III) reducing microbial activity. What was unknown was the concentration of phosphate that could be removed by this process, and whether it was relevant to mixed microbial systems like septic tank wastewater. Data presented here demonstrate that significant concentrations of phosphate (12-14mM) were removed as vivianite in growing cultures of Geobacter metallireducens strain GS-15. Vivianite precipitates were identified on the cell surfaces and within multi cell clusters using TEM-EDX; the mineral phases were directly characterized using XRD. Phosphate was also removed in dilute and raw (undiluted) septic wastewater amended with different forms of Fe(III) including solid phase and soluble Fe(III). Vivianite precipitates were recovered and identified using XRD, along with siderite (ferrous carbonate), which was expected given that the systems were likely bicarbonate buffered. These data demonstrate that ferric iron amendments in septic wastewater increase phosphate removal as the mineral vivianite, and this may be a good strategy for phosphate attenuation in the septic tank portion of onsite wastewater systems. Copyright © 2013 Elsevier Ltd. All rights reserved.

Raman spectroscopy of stercorite H(NH 4)Na(PO 4)·4H 2O--A cave mineral from Petrogale Cave, Madura, Eucla, Western Australia

NASA Astrophysics Data System (ADS)

Frost, Ray L.; Palmer, Sara J.

2011-09-01

Raman spectroscopy complimented with infrared spectroscopy has been used to characterise the mineral stercorite H(NH 4)Na(PO 4)·4H 2O. The mineral stercorite originated from the Petrogale Cave, Madura, Eucla, Western Australia. This cave is one of many caves in the Nullarbor Plain in the South of Western Australia. These caves have been in existence for eons of time and have been dated at more than 550 million years old. The mineral is formed by the reaction of bat guano chemicals on calcite substrates. A single Raman band at 920 cm -1 defines the presence of phosphate in the mineral. Antisymmetric stretching bands are observed in the infrared spectrum at 1052, 1097, 1135 and 1173 cm -1. Raman spectroscopy shows the mineral is based upon the phosphate anion and not the hydrogen phosphate anion. Raman and infrared bands are found and assigned to PO 43-, H 2O, OH and NH stretching vibrations. The detection of stercorite by Raman spectroscopy shows that the mineral can be readily determined; as such the application of a portable Raman spectrometer in a 'cave' situation enables the detection of minerals, some of which may remain to be identified.

Complementary effects of multi-protein components on biomineralization in vitro

PubMed Central

Ba, Xiaolan; Rafailovich, Miriam; Meng, Yizhi; Pernodet, Nadine; Wirick, Sue; Füredi-Milhofer, Helga; Qin, Yi-Xian; DiMasi, Elaine

2016-01-01

The extracellular matrix (ECM) is composed of mixed protein fibers whose precise composition affects biomineralization. New methods are needed to probe the interactions of these proteins with calcium phosphate mineral and with each other. Here we follow calcium phosphate mineralization on protein fibers self-assembled in vitro from solutions of fibronectin, elastin and their mixture. We probe the surface morphology and mechanical properties of the protein fibers during the early stages. The development of mineral crystals on the protein matrices is also investigated. In physiological mineralization solution, the elastic modulus of the fibers in the fibronectin-elastin mixture increases to a greater extent than that of the fibers from either pure protein. In the presence of fibronectin, longer exposure in the mineral solution leads to the formation of amorphous calcium phosphate particles templated along the self-assembled fibers, while elastin fibers only collect calcium without any mineral observed during early stage. TEM images confirm that small needle-shape crystals are confined inside elastin fibers which suppress the release of mineral outside the fibers during late stage, while hydroxyapatite crystals form when fibronectin is present. These results demonstrate complementary actions of the two ECM proteins fibronectin and elastin to collect cations and template mineral, respectively. PMID:20035875

Biomimetic nanoparticles with polynucleotide and PEG mixed-monolayers enhance calcium phosphate mineralization

NASA Astrophysics Data System (ADS)

Vasconcellos, Kayla B.; McHugh, Sean M.; Dapsis, Katherine J.; Petty, Alexander R.; Gerdon, Aren E.

2013-09-01

Biomineralization of hydroxyapatite (Ca10(PO4)6(OH)2) is of significant importance in biomedical applications such as bone and dental repair, and biomimetic control of mineral formation may lead to more effective restorative procedures. Gold nanoparticles are functional scaffolds on which to assemble multi-component monolayers capable of mimicking protein activity in the templated synthesis of calcium phosphate. The goal of this research was to explore nanoparticle templates with mixed-monolayers of uncharged polar polyethylene glycol (PEG) molecules and highly charged polynucleotide and amino acid molecules in their ability to influence mineralization rates and mineral particle size and morphology. This research demonstrates through time-resolved optical density and dynamic light scattering measurements that the combination of tiopronin, PEG, and DNA presented on a nanoparticle surface decreases nanoparticle aggregation from 59 to 21 nm solvated radius, increases mineralization kinetics from 1.5 × 10-3 to 3.1 × 10-3 OD/min, and decreases mineral particle size from 685 to 442 nm average radius. FT-IR and TEM data demonstrate that mineralized material, while initially amorphous, transforms to a semi-crystalline material when guided by template interactions. This demonstrates that surface-tailored monolayer protected cluster scaffolds are successful and controllable mineralization templates with further potential for biomedical applications involving calcium phosphate and other biomaterials.

Competing retention pathways of uranium upon reaction with Fe(II)

NASA Astrophysics Data System (ADS)

Massey, Michael S.; Lezama-Pacheco, Juan S.; Jones, Morris E.; Ilton, Eugene S.; Cerrato, José M.; Bargar, John R.; Fendorf, Scott

2014-10-01

Biogeochemical retention processes, including adsorption, reductive precipitation, and incorporation into host minerals, are important in contaminant transport, remediation, and geologic deposition of uranium. Recent work has shown that U can become incorporated into iron (hydr)oxide minerals, with a key pathway arising from Fe(II)-induced transformation of ferrihydrite, (Fe(OH)3·nH2O) to goethite (α-FeO(OH)); this is a possible U retention mechanism in soils and sediments. Several key questions, however, remain unanswered regarding U incorporation into iron (hydr)oxides and this pathway's contribution to U retention, including: (i) the competitiveness of U incorporation versus reduction to U(IV) and subsequent precipitation of UO2; (ii) the oxidation state of incorporated U; (iii) the effects of uranyl aqueous speciation on U incorporation; and, (iv) the mechanism of U incorporation. Here we use a series of batch reactions conducted at pH ∼7, [U(VI)] from 1 to 170 μM, [Fe(II)] from 0 to 3 mM, and [Ca] at 0 or 4 mM coupled with spectroscopic examination of reaction products of Fe(II)-induced ferrihydrite transformation to address these outstanding questions. Uranium retention pathways were identified and quantified using extended X-ray absorption fine structure (EXAFS) spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. Analysis of EXAFS spectra showed that 14-89% of total U was incorporated into goethite, upon reaction with Fe(II) and ferrihydrite. Uranium incorporation was a particularly dominant retention pathway at U concentrations ⩽50 μM when either uranyl-carbonato or calcium-uranyl-carbonato complexes were dominant, accounting for 64-89% of total U. With increasing U(VI) and Fe(II) concentrations, U(VI) reduction to U(IV) became more prevalent, but U incorporation remained a functioning retention pathway. These findings highlight the potential importance of U(V) incorporation within iron oxides as a retention process of U across a wide range of biogeochemical environments and the sensitivity of uranium retention processes to operative (bio)geochemical conditions.

Competing retention pathways of uranium upon reaction with Fe(II)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Massey, Michael S.; Lezama Pacheco, Juan S.; Jones, Morris

Biogeochemical retention processes, including adsorption, reductive precipitation, and incorporation into host minerals, are important in contaminant transport, remediation, and geologic deposition of uranium. Recent work has shown that U can become incorporated into iron (hydr)oxide minerals, with a key pathway arising from Fe(II)-induced transformation of ferrihydrite, (Fe(OH)3•nH2O) to goethite (α-FeO(OH)); this is a possible U retention mechanism in soils and sediments. Several key questions, however, remain unanswered regarding U incorporation into iron (hydr)oxides and this pathway’s contribution to U retention, including: (i) the competitiveness of U incorporation versus reduction to U(IV) and subsequent precipitation of UO2; (ii) the oxidation statemore » of incorporated U; (iii) the effects of uranyl aqueous speciation on U incorporation; and, (iv) the mechanism of U incorporation. Here we use a series of batch reactions conducted at pH ~7, [U(VI)] from 1 to 170 μM, [Fe(II)] from 0 to 3 mM, and [Ca] at 0 or 4 mM) coupled with spectroscopic examination of reaction products of Fe(II)-induced ferrihydrite transformation to address these outstanding questions. Uranium retention pathways were identified and quantified using extended x-ray absorption fine structure (EXAFS) spectroscopy, x-ray powder diffraction, x-ray photoelectron spectroscopy, and transmission electron microscopy. Analysis of EXAFS spectra showed that 14 to 89% of total U was incorporated into goethite, upon reaction with Fe(II) and ferrihydrite. Uranium incorporation was a particularly dominant retention pathway at U concentrations ≤ 50 μM when either uranyl-carbonato or calcium-uranyl-carbonato complexes were dominant, accounting for 64 to 89% of total U. With increasing U(VI) and Fe(II) concentrations, U(VI) reduction to U(IV) became more prevalent, but U incorporation remained a functioning retention pathway. These findings highlight the potential importance of U(V) incorporation within iron oxides as a retention process of U across a wide range of biogeochemical environments and the sensitivity of uranium retention processes to operative (bio)geochemical conditions.« less

The effects of nocturnal compared with conventional hemodialysis on mineral metabolism: A randomized-controlled trial.

PubMed

Walsh, Michael; Manns, Braden J; Klarenbach, Scott; Tonelli, Marcello; Hemmelgarn, Brenda; Culleton, Bruce

2010-04-01

Hyperphosphatemia is common among patients receiving dialysis and is associated with increased mortality. Nocturnal hemodialysis (NHD) is a long, slow dialytic modality that may improve hyperphosphatemia and disorders of mineral metabolism. We performed a randomized-controlled trial of NHD compared with conventional hemodialysis (CvHD); in this paper, we report detailed results of mineral metabolism outcomes. Prevalent patients were randomized to receive NHD 5 to 6 nights per week for 6to 10 hours per night or to continue CvHD thrice weekly for 6 months. Oral phosphate binders and vitamin D analogs were adjusted to maintain phosphate, calcium and parathyroid hormone (PTH) levels within recommended targets. Compared with CvHD patients, patients in the NHD group had a significant decrease in serum phosphate over the course of the study (0.49 mmol/L, 95% confidence interval 0.24-0.74; P=0.002) despite a significant reduction in the use of phosphate binders. Sixty-one percent of patients in the NHD group compared with 20% in the CvHD group had a decline in intact PTH (P=0.003). Nocturnal hemodialysis lowers serum phosphate, calcium-phosphate product and requirement for phosphate binders. The effects of NHD on PTH are variable. The impact of these changes on long-term cardiovascular and bone-related outcomes requires further investigation.

Comparative study of uranyl(VI) and -(V) carbonato complexes in an aqueous solution.

PubMed

Ikeda, Atsushi; Hennig, Christoph; Tsushima, Satoru; Takao, Koichiro; Ikeda, Yasuhisa; Scheinost, Andreas C; Bernhard, Gert

2007-05-14

Electrochemical, complexation, and electronic properties of uranyl(VI) and -(V) carbonato complexes in an aqueous Na2CO3 solution have been investigated to define the appropriate conditions for preparing pure uranyl(V) samples and to understand the difference in coordination character between UO22+ and UO2+. Cyclic voltammetry using three different working electrodes of platinum, gold, and glassy carbon has suggested that the electrochemical reaction of uranyl(VI) carbonate species proceeds quasi-reversibly. Electrolysis of UO22+ has been performed in Na2CO3 solutions of more than 0.8 M with a limited pH range of 11.7 < pH < 12.0 using a platinum mesh electrode. It produces a high purity of the uranyl(V) carbonate solution, which has been confirmed to be stable for at least 2 weeks in a sealed glass cuvette. Extended X-ray absorption fine structure (EXAFS) measurements revealed the structural arrangement of uranyl(VI) and -(V) tricarbonato complexes, [UO2(CO3)3]n- [n = 4 for uranyl(VI), 5 for uranyl(V)]. The bond distances of U-Oax, U-Oeq, U-C, and U-Odist are determined to be 1.81, 2.44, 2.92, and 4.17 A for the uranyl(VI) complex and 1.91, 2.50, 2.93, and 4.23 A for the uranyl(V) complex, respectively. The validity of the structural parameters obtained from EXAFS has been supported by quantum chemical calculations for the uranyl(VI) complex. The uranium LI- and LIII-edge X-ray absorption near-edge structure spectra have been interpreted in terms of electron transitions and multiple-scattering features.

Structure and chemical composition of the dentin-enamel junction analyzed by Confocal Raman Microscopy

NASA Astrophysics Data System (ADS)

Desoutter, A.; Salehi, H.; Slimani, A.; Marquet, P.; Jacquot, B.; Tassery, H.; Cuisinier, F. J. G.

2014-02-01

The structure and chemical composition of the human dentin-enamel junction (DEJ) was studied using confocal Raman microscopy - a chemical imaging technique. Slices of non-fixed, sound teeth were prepared with an Isomet diamond saw and scanned with Witec Alpha300R system. The combination of different characteristics peaks of phosphate, carbonate and organic matrix (respectively 960, 1072 and 1545 cm-1), generates images representing the chemical composition of the DEJ area. Images are also calculated using peak ratios enabling precise determination of the chemical composition across the DEJ. Then, with two characterized peaks, different pictures are calculated to show the ratio of two components. The images of the spatial distribution of mineral phosphate (960cm-1) to organic matrix (1545 cm-1) ratios, mineral carbonates (1072cm-1) to mineral phosphate ratios; and mineral carbonates to organic matrix ratios were reconstructed. Cross sectional and calculated graphic profile show the variations of the different chemical component ratios through the enamel and the dentin. Phosphate to organic ratio shows an accumulation of organic material under the enamel surface. The cross sectional profile of these pictures shows a high phosphate content compared to enamel in the vicinity of the DEJ. The Confocal Raman imaging technique can be used to further provide full chemical imaging of tooth, particularly of the whole DEJ and to study enamel and dentin decay.

Interactions of phosphate solubilising microorganisms with natural rare-earth phosphate minerals: a study utilizing Western Australian monazite.

PubMed

Corbett, Melissa K; Eksteen, Jacques J; Niu, Xi-Zhi; Croue, Jean-Philippe; Watkin, Elizabeth L J

2017-06-01

Many microbial species are capable of solubilising insoluble forms of phosphate and are used in agriculture to improve plant growth. In this study, we apply the use of known phosphate solubilising microbes (PSM) to the release of rare-earth elements (REE) from the rare-earth phosphate mineral, monazite. Two sources of monazite were used, a weathered monazite and mineral sand monazite, both from Western Australia. When incubated with PSM, the REE were preferentially released into the leachate. Penicillum sp. released a total concentration of 12.32 mg L -1 rare-earth elements (Ce, La, Nd, and Pr) from the weathered monazite after 192 h with little release of thorium and iron into solution. However, cultivation on the mineral sands monazite resulted in the preferential release of Fe and Th. Analysis of the leachate detected the production of numerous low-molecular weight organic acids. Gluconic acid was produced by all microorganisms; however, other organic acids produced differed between microbes and the monazite source provided. Abiotic leaching with equivalent combinations of organic acids resulted in the lower release of REE implying that other microbial processes are playing a role in solubilisation of the monazite ore. This study demonstrates that microbial solubilisation of monazite is promising; however, the extent of the reaction is highly dependent on the monazite matrix structure and elemental composition.

Mineral induction by immobilized phosphoproteins

NASA Technical Reports Server (NTRS)

Saito, T.; Arsenault, A. L.; Yamauchi, M.; Kuboki, Y.; Crenshaw, M. A.

1997-01-01

Dentin phosphoproteins are thought to have a primary role in the deposition of mineral on the collagen of dentin. In this study we determined the type of binding between collagen and phosphoproteins necessary for mineral formation onto collagen fibrils and whether the phosphate esters are required. Bovine dentin phosphophoryn or phosvitin from egg yolk were immobilized on reconstituted skin type I collagen fibrils by adsorption or by covalent cross-linking. In some samples the ester phosphate was removed from the covalently cross-linked phosphoproteins by treatment with acid phosphatase. All samples were incubated at 37 degrees C in metastable solutions that do not spontaneously precipitate. Reconstituted collagen fibrils alone did not induce mineral formation. The phosphoproteins adsorbed to the collagen fibrils desorbed when the mineralization medium was added, and mineral was not induced. The mineral induced by the cross-linked phosphoproteins was apatite, and the crystals were confined to the surface of the collagen fibrils. With decreasing medium saturation the time required for mineral induction increased. The interfacial tensions calculated for apatite formation by either phosphoprotein cross-linked to collagen were about the same as that for phosphatidic acid liposomes and hydroxyapatite. This similarity in values indicates that the nucleation potential of these highly phosphorylated surfaces is about the same. It is concluded that phosphoproteins must be irreversibly bound to collagen fibrils for the mineralization of the collagen network in solutions that do not spontaneously precipitate. The phosphate esters of phosphoproteins are required for mineral induction, and the carboxylate groups are not sufficient.

Data set of world phosphate mines, deposits, and occurrences: Part A. geologic data; Part B. location and mineral economic data

USGS Publications Warehouse

Chernoff, Carlotta B.; Orris, G.J.

2002-01-01

An inventory of more than 1,600 world phosphate mines, deposits, and occurrences was compiled from smaller data sets collected as part of multiple research efforts by Carlotta Chernoff, University of Arizona, and Greta Orris, U.S. Geological Survey. These data have been utilized during studies of black shale depositional environments and to construct phosphate deposit models. The compiled data have been edited for consistency and additional location information has been added where possible. The database of compiled phosphate information is being released in two sections; the geologic data in one section and the location and mineral economic data in the second. This report, U.S. Geological Survey Open-File Report 02–156–A, contains the geologic data and is best used with the complimentary data contained in Open-File Report 02–156–B. U.S. Geological Survey Open-File Report 02–156–B contains commodity data, location and analytical data, a variety of mineral economic data, reference information, and pointers to related records in the U.S. Geological Survey National mineral databases—MASMILS and MRDS.

The phosphate mineral arrojadite-(KFe) and its spectroscopic characterization

NASA Astrophysics Data System (ADS)

Frost, Ray L.; Xi, Yunfei; Scholz, Ricardo; Horta, Laura Frota Campos

2013-05-01

The arrojadite-(KFe) mineral has been analyzed using a combination of scanning electron microscopy and a combination of Raman and infrared spectroscopy. The origin of the mineral is Rapid Creek sedimentary phosphatic iron formation, northern Yukon. The formula of the mineral was determined as KNaCaNa(FeMgMn)Al(PO)10.85(POOH)(OH)2. The complexity of the mineral formula is reflected in the spectroscopy. Raman bands at 975, 991 and 1005 cm-1 with shoulder bands at 951 and 1024 cm-1 are assigned to the PO43- ν1 symmetric stretching modes. The Raman bands at 1024, 1066, 1092, 1123, 1148 and 1187 cm-1 are assigned to the PO43- ν3 antisymmetric stretching modes. A series of Raman bands observed at 540, 548, 557, 583, 604, 615 and 638 cm-1 are attributed to the ν4 out of plane bending modes of the PO4 and H2PO4 units. The ν2 PO4 and H2PO4 bending modes are observed at 403, 424, 449, 463, 479 and 513 cm-1. Hydroxyl and water stretching bands are readily observed. Vibrational spectroscopy enables new information about the complex phosphate mineral arrojadite-(KFe) to be obtained.

Fe-Ca-phosphate, Fe-silicate, and Mn-oxide minerals in concretions from the Monterey Formation

USGS Publications Warehouse

Medrano, M.D.; Piper, D.Z.

1997-01-01

Concentrically zoned phosphatic-enriched concretions were collected at three sites from the Monterey Formation. The following minerals were identified: vivianite, lipscombite, rockbridgeite, leucophosphite, mitridatite, carbonate fluorapatite, nontronite, todorokite, and barite. The mineralogy of the concretions was slightly different at each of the three collection sites. None of the concretions contains all of the minerals, but the spatial distribution of minerals in individual concretions, overlapping mineralogies between different concretions, and the geochemical properties of the separate minerals suggest a paragenesis represented by the above order. Eh increased from the precipitation of vivianite to that of rockbridgeite/lipscombite. The precipitation of leucophosphite, then mitridatite, carbonate fluorapatite and todorokite/Fe-oxide indicates increasing pH. Concretion growth culminated with the precipitation of todorokite, a Mn oxide, and minor amounts of barite along microfractures. Conspicuously absent are Fe-sulfide and Mn-phosphate minerals. The concretions are hosted by finely laminated diatomite. The laminations exhibit little to no deformation around the concretions, requiring that the concretions formed after compaction. We interpret this sediment feature and the paragenesis as recording the evolving pore-water chemistry as the formation was uplifted into the fresh-ground-water zone.

Micro-SHINE Uranyl Sulfate Irradiations at the Linac

DOE Office of Scientific and Technical Information (OSTI.GOV)

Youker, Amanda J.; Kalensky, Michael; Chemerisov, Sergey

2016-08-01

Peroxide formation due to water radiolysis in a uranyl sulfate solution is a concern for the SHINE Medical Technologies process in which Mo-99 is generated from the fission of dissolved low enriched uranium. To investigate the effects of power density and fission on peroxide formation and uranyl-peroxide precipitation, uranyl sulfate solutions were irradiated using a 50-MeV electron linac as part of the micro-SHINE experimental setup. Results are given for uranyl sulfate solutions with both high and low enriched uranium irradiated at different linac powers.

Composition for detecting uranyl

DOEpatents

Baylor, Lewis C.; Stephens, Susan M.

1995-01-01

A composition for detecting the presence and concentration of a substance such as uranyl, comprising an organohalide covalently bonded to an indicator for said substance. The composition has at least one active OH site for forming a complex with the substance to be detected. The composition is made by reacting equimolar amounts of the indicator and the organohalide in a polar organic solvent. The absorbance spectrum of the composition-uranyl complex is shifted with respect to the absorbance spectrum of the indicator-uranyl complex, to provide better spectral resolution for detecting uranyl.

Re-evaluation and reconstruction of water purification system using soil. I. Assessment of soil as a sorbent of humic substances and phosphate ion.

PubMed

Fujikawa, Y; Hamasaki, T; Sugahara, M; Ozaki, H; Prasai, G; Yano, T; Imada, R; Tainaka, Y; Nakamura, W; Haruki, F

2004-01-01

The purpose of our study is to develop a treatment procedure for humic substances (HS hereafter) and phosphate ion in wastewater and environmental water by percolation of the water through a constructed soil layer at the hydraulic loading of a few metres per day. In the present work, batch sorption tests were conducted for more than 80 samples of soil, sludge, mineral and organic materials in order to find good sorbents for fulvic acid (FA hereafter) and phosphate ion. The results showed that the sorption of FA was high for some charcoal, and apatite and goethite minerals. Comparatively high sorption of FA was found for some Andosols and volcanic ash soil. Significant sorption of phosphate ion, on the other hand, was found for various types of soil, sludge from water treatment plants and some waste materials. The linear isotherm was obtained for the sorption of FA to a charcoal, apatite and goethite minerals, and Andosols.

A vibrational spectroscopic study of the silicate mineral lomonosovite Na5Ti2(Si2O7)(PO4)O2

NASA Astrophysics Data System (ADS)

Frost, Ray L.; López, Andrés; Theiss, Frederick L.; Graça, Leonardo M.; Scholz, Ricardo

2015-01-01

The mineral lomonosovite has been studied using a combination of scanning electron microscopy with energy dispersive X-ray analysis and vibrational spectroscopy. Qualitative chemical analysis gave Si, P, Na and Ti as the as major elements with small amounts of Mn, Ca, Fe and Al. The mineral lomonosovite has a formula Na5Ti2(Si2O7)(PO4)O2. Raman bands observed at 909, 925 and 939 cm-1 are associated with phosphate units. Raman bands found at 975, 999, 1070, 1080 and 1084 cm-1 are attributed to siloxane stretching vibrations. The observation of multiple bands in both the phosphate stretching and bending regions supports the concept that the symmetry of the phosphate anion in the structure of lomonosovite is significantly reduced. Infrared spectroscopy identifies bands in the water stretching and bending regions, thus suggesting that water is involved with the structure of lomonosovite either through adsorption on the surface or by bonding to the phosphate units.

Magnetic properties of the Bled El Hadba phosphate-bearing formation (Djebel Onk, Algeria): Consequences of the enrichment of the phosphate ore deposit

NASA Astrophysics Data System (ADS)

Bezzi, Nacer; Aïfa, Tahar; Merabet, Djoudi; Pivan, Jean-Yves

2008-02-01

To improve the enrichment of the Thanetian marine phosphate ore deposit from the quarry of Bled El Hadba (Djebel Onk, Algeria) before its exploitation, we first conducted a joint study using different techniques for comparison. These studies reveal that magnetic minerals play a significant role within the matrix of the central productive unit which is squeezed between two other units. Magnetic separation procedures show that there are some positive correlations between magnetic susceptibility and grain size fraction (80-250 μm). These dolomite-rich fractions are more clearly separated. Different tools were used to characterize the magnetic minerals (X-ray, microprobe, differential scanning calorimetry, thermogravimetric and thermomagnetic analyses). They show correlations between magnetic phases and the presence of associated magnetic minerals within the matrix or included in the phosphate ore deposit. They enabled us to distinguish a series of magnetic minerals (magnetite, hematite, maghemite, goethite, ilmenite, pyrite, iron-titanium oxide and titanium oxide sulphate) and to determine that Fe and Ti are prevalent in the separated fractions, following the same variation as Mg. The phosphorous (phosphate) rate is higher in the non-magnetic material, especially in the layers that are rich in dolomitic carbonates (upper and lower units), which could be trapped within the dolomitic matrix, while Magnesium (dolomite) is more important in the magnetic fraction. The separation of phosphate elements and dolomite carbonates is effective and therefore the ore can be enriched through magnetic procedures. Comparison between products enriched by magnetic separation, flotation and calcination showed important differences, chemically, economically and technically speaking.

Effects of calcium and phosphate on uranium(IV) oxidation: Comparison between nanoparticulate uraninite and amorphous UIV-phosphate

NASA Astrophysics Data System (ADS)

Latta, Drew E.; Kemner, Kenneth M.; Mishra, Bhoopesh; Boyanov, Maxim I.

2016-02-01

The mobility of uranium in subsurface environments depends strongly on its redox state, with UIV phases being significantly less soluble than UVI minerals. This study compares the oxidation kinetics and mechanisms of two potential products of UVI reduction in natural systems, a nanoparticulate UO2 phase and an amorphous UIV-Ca-PO4 analog to ningyoite (CaUIV(PO4)2·1-2H2O). The valence of U was tracked by X-ray absorption near-edge spectroscopy (XANES), showing similar oxidation rate constants for UIVO2 and UIV-phosphate in solutions equilibrated with atmospheric O2 and CO2 at pH 7.0 (kobs,UO2 = 0.17 ± 0.075 h-1 vs. kobs,UIVPO4 = 0.30 ± 0.25 h-1). Addition of up to 400 μM Ca and PO4 decreased the oxidation rate constant by an order of magnitude for both UO2 and UIV-phosphate. The intermediates and products of oxidation were tracked by electron microscopy, powder X-ray diffraction (pXRD), and extended X-ray absorption fine-structure spectroscopy (EXAFS). In the absence of Ca or PO4, the product of UO2 oxidation is Na-uranyl oxyhydroxide (under environmentally relevant concentrations of sodium, 15 mM NaClO4 and low carbonate concentration), resulting in low concentrations of dissolved UVI (<2.5 × 10-7 M). Oxidation of UIV-phosphate produced a Na-autunite phase (Na2(UO2)PO4·xH2O), resulting in similarly low dissolved U concentrations (<7.3 × 10-8 M). When Ca and PO4 are present in the solution, the EXAFS data and the solubility of the UVI phase resulting from oxidation of UO2 and UIV-phosphate are consistent with the precipitation of Na-autunite. Bicarbonate extractions and Ca K-edge X-ray absorption spectroscopy of oxidized solids indicate the formation of a Ca-UVI-PO4 layer on the UO2 surface and suggest a passivation layer mechanism for the decreased rate of UO2 oxidation in the presence of Ca and PO4. Interestingly, the extractions were unable to remove all of the oxidized U from partially oxidized UO2 solids, suggesting that oxidized U is distributed between the interior of the UO2 nanoparticles and the labile surface layer. Accounting for the entire pool of oxidized U by XANES is the likely reason for the higher UO2 oxidation rate constants determined here relative to prior studies. Our results suggest that the natural presence or addition of Ca and PO4 in groundwater could slow the rates of UIV oxidation, but that the rates are still fast enough to cause complete oxidation of UIV within days under fully oxygenated conditions.

Effects of calcium and phosphate on uranium(IV) oxidation: Comparison between nanoparticulate uraninite and amorphous U IV–phosphate

DOE PAGES

Latta, Drew E.; Kemner, Kenneth M.; Mishra, Bhoopesh; ...

2015-11-17

The mobility of uranium in subsurface environments depends strongly on its redox state, with U IV phases being significantly less soluble than U VI minerals. This study compares the oxidation kinetics and mechanisms of two potential products of U VI reduction in natural systems, a nanoparticulate UO 2 phase and an amorphous U IV–Ca–PO 4 analog to ningyoite (CaU IV(PO 4) 2·1–2H 2O). The valence of U was tracked by X-ray absorption near-edge spectroscopy (XANES), showing similar oxidation rate constants for U IVO 2 and U IV–phosphate in solutions equilibrated with atmospheric O 2 and CO 2 at pH 7.0more » (k obs,UO2 = 0.17 ± 0.075 h -1 vs. k obs,U IV PO4 = 0.30 ± 0.25 h -1). Addition of up to 400 μM Ca and PO 4 decreased the oxidation rate constant by an order of magnitude for both UO 2 and U IV–phosphate. The intermediates and products of oxidation were tracked by electron microscopy, powder X-ray diffraction (pXRD), and extended X-ray absorption fine-structure spectroscopy (EXAFS). In the absence of Ca or PO 4, the product of UO 2 oxidation is Na–uranyl oxyhydroxide (under environmentally relevant concentrations of sodium, 15 mM NaClO 4 and low carbonate concentration), resulting in low concentrations of dissolved U VI (<2.5 × 10 -7 M). Oxidation of U IV–phosphate produced a Na-autunite phase (Na 2(UO 2)PO 4·xH 2O), resulting in similarly low dissolved U concentrations (<7.3 × 10 -8 M). When Ca and PO 4 are present in the solution, the EXAFS data and the solubility of the UVI phase resulting from oxidation of UO 2 and UIV–phosphate are consistent with the precipitation of Na-autunite. Bicarbonate extractions and Ca K-edge X-ray absorption spectroscopy of oxidized solids indicate the formation of a Ca–UVI–PO 4 layer on the UO 2 surface and suggest a passivation layer mechanism for the decreased rate of UO 2 oxidation in the presence of Ca and PO 4. Interestingly, the extractions were unable to remove all of the oxidized U from partially oxidized UO 2 solids, suggesting that oxidized U is distributed between the interior of the UO 2 nanoparticles and the labile surface layer. Accounting for the entire pool of oxidized U by XANES is the likely reason for the higher UO 2 oxidation rate constants determined here relative to prior studies. In conclusion, our results suggest that the natural presence or addition of Ca and PO 4 in groundwater could slow the rates of U IV oxidation, but that the rates are still fast enough to cause complete oxidation of U IV within days under fully oxygenated conditions.« less

Precipitation characteristics of uranyl ions at different pHs depending on the presence of carbonate ions and hydrogen peroxide.

PubMed

Kim, Kwang-Wook; Kim, Yeon-Hwa; Lee, Se-yoon; Lee, Jae-Won; Joe, Kih-Soo; Lee, Eil-Hee; Kim, Jong-Seung; Song, Kyuseok; Song, Kee-Chan

2009-04-01

This work studied the dissolution of uranium dioxide and precipitation characteristics of uranyl ions in alkaline and acidic solutions depending on the presence of carbonate ions and H2O2 in the solutions at different pHs controlled by adding HNO3 or NaOH in the solution. The chemical structures of the precipitates generated in different conditions were evaluated and compared by using XRD, SEM, TG-DT, and IR analyses together. The sizes and forms of the precipitates in the solutions were evaluated, as well. The uranyl ions were precipitated in the various forms, depending on the solution pH and the presences of hydrogen peroxide and carbonate ions in the solution. In a 0.5 M Na2CO3 solution with H2O2, where the uranyl ions formed mixed uranyl peroxy-carbonato complexes, the uranyl ions were precipitated as a uranium peroxide of UO4(H20)4 at pH 3-4, and precipitated as a clarkeite of Na2U2Ox(OH)y(H2O)z above pH 13. In the same carbonate solution without H2O2, where the uranyl ions formed uranyl tris-carbonato complex, the uranyl ions were observed to be precipitated as a different form of clarkeite above pH 13. The precipitate of uranyl ions in a nitrate solution without carbonate ions and H2O2 at a high pH were studied together to compare the precipitate forms in the carbonate solutions.

Adsorption of gluconate and uranyl on C-S-H phases: Combination of wet chemistry experiments and molecular dynamics simulations for the binary systems

NASA Astrophysics Data System (ADS)

Androniuk, Iuliia; Landesman, Catherine; Henocq, Pierre; Kalinichev, Andrey G.

2017-06-01

As a first step in developing better molecular scale understanding of the effects of organic additives on the adsorption and mobility of radionuclides in cement under conditions of geological nuclear waste repositories, two complementary approaches, wet chemistry experiments and molecular dynamics (MD) computer simulations, were applied to study the sorption behaviour of two simple model systems: gluconate and uranyl on calcium silicate hydrate phases (C-S-H) - the principal mineral component of hardened cement paste (HCP). Experimental data on sorption and desorption kinetics and isotherms of adsorption for gluconate/C-S-H and U(VI)/C-S-H binary systems were collected and quantitatively analysed for C-S-H samples synthesised with various Ca/Si ratios (0.83, 1.0, 1.4) corresponding to various stages of HCP aging and degradation. Gluconate labelled with 14C isotope was used in order to improve the sensitivity of analytical detection technique (LSC) at particularly low concentrations (10-8-10-5 mol/L). There is a noticeable effect of Ca/Si ratio on the gluconate sorption on C-S-H, with stronger sorption at higher Ca/Si ratios. Sorption of organic anions on C-S-H is mediated by the presence of Ca2+ at the interface and strongly depends on the surface charge and Ca2+ concentration. In parallel, classical MD simulations of the same model systems were performed in order to identify specific surface sorption sites most actively involved in the sorption of gluconate and uranyl on C-S-H and to clarify molecular mechanisms of adsorption.

Connective Tissue Mineralization in Abcc6−/− Mice, a Model for Pseudoxanthoma Elasticum

PubMed Central

Kavukcuoglu, N. Beril; Li, Qiaoli; Pleshko, Nancy; Uitto, Jouni

2012-01-01

Pseudoxanthoma elasticum (PXE) is a heritable multisystem disorder characterized by ectopic mineralization. However, the structure of the mineral deposits, their interactions with the connective tissue matrix, and the details of the progressive maturation of the mineral crystals are currently unknown. In this study, we examined the mineralization processes in Abcc6−/− mice, a model system for PXE, by energy dispersive X-ray, and Fourier transform infrared imaging spectroscopy (FT-IRIS). The results indicated that the principal components of the mineral deposits were calcium and phosphate which co-localized within the histologically demonstrable lesions determined by topographic mapping. The Ca/P ratio increased in samples with progressive mineralization reaching the value comparable to that in endochondral bone. A progressive increase in mineralization was also reflected by increased mineral-to-matrix ratio determined by FT-IRIS. Determination of the mineral phases by FT-IRIS suggested progressive maturation of the mineral deposits from amorphous calcium phosphate to hydroxyapatite. These results provide critical information of the mechanisms of mineralization in PXE, with potential pharmacologic implications. PMID:22421595

Geochemistry of vanadium in an epigenetic, sandstone-hosted vanadium- uranium deposit, Henry Basin, Utah

USGS Publications Warehouse

Wanty, R.B.; Goldhaber, M.B.; Northrop, H.R.

1990-01-01

The epigenetic Tony M vanadium-uranium orebody in south-central Utah is hosted in fluvial sandstones of the Morrison Formation (Upper Jurassic). Measurements of the relative amounts of V+3 and V +4 in ore minerals show that V+3 is more abundant. Thermodynamic calculations show that vanadium was more likely transported to the site of mineralization as V+4. The ore formed as V+4 was reduced by hydrogen sulfide, followed by hydrolysis and precipitation of V+3 in oxide minerals or chlorite. Uranium was transported as uranyl ion (U+6), or some complex thereof, and reduced by hydrogen sulfide, forming coffinite. Detrital organic matter in the rocks served as the carbon source for sulfate-reducing bacteria. Vanadium most likely was derived from the dissolution of iron-titanium oxides. Uranium probably was derived from the overlying Brushy Basin Member of the Morrison Formation. Previous studies have shown that the ore formed at the density-stratified interface between a basinal brine and dilute meteoric water. The mineralization processes described above occurred within the mixing zone between these two fluids. -from Authors

Comparison of the adjuvant activity of aluminum hydroxide and calcium phosphate on the antibody response towards Bothrops asper snake venom.

PubMed

Olmedo, Hidekel; Herrera, María; Rojas, Leonardo; Villalta, Mauren; Vargas, Mariángela; Leiguez, Elbio; Teixeira, Catarina; Estrada, Ricardo; Gutiérrez, José María; León, Guillermo; Montero, Mavis L

2014-01-01

The adjuvanticity of aluminum hydroxide and calcium phosphate on the antibody response in mice towards the venom of the snake Bothrops asper was studied. It was found that, in vitro, most of the venom proteins are similarly adsorbed by both mineral salts, with the exception of some basic phospholipases A2, which are better adsorbed by calcium phosphate. After injection, the adjuvants promoted a slow release of the venom, as judged by the lack of acute toxicity when lethal doses of venom were administered to mice. Leukocyte recruitment induced by the venom was enhanced when it was adsorbed on both mineral salts; however, venom adsorbed on calcium phosphate induced a higher antibody response towards all tested HPLC fractions of the venom. On the other hand, co-precipitation of venom with calcium phosphate was the best strategy for increasing: (1) the capacity of the salt to couple venom proteins in vitro; (2) the venom ability to induce leukocyte recruitment; (3) phagocytosis by macrophages; and (4) a host antibody response. These findings suggest that the chemical nature is not the only one determining factor of the adjuvant activity of mineral salts.

43 CFR 3511.10 - Do certain leases allow me to mine other commodities as well?

Code of Federal Regulations, 2012 CFR

2012-10-01

... phosphate lease allows you to use deposits of silica, limestone or other rock on the lease for use in the processing or refining of phosphate, phosphate rock, and associated minerals mined from the leased lands. You...

43 CFR 3511.10 - Do certain leases allow me to mine other commodities as well?

Code of Federal Regulations, 2011 CFR

2011-10-01

... phosphate lease allows you to use deposits of silica, limestone or other rock on the lease for use in the processing or refining of phosphate, phosphate rock, and associated minerals mined from the leased lands. You...

Phosphate-a poison for humans?

PubMed

Komaba, Hirotaka; Fukagawa, Masafumi

2016-10-01

Maintenance of phosphate balance is essential for life, and mammals have developed a sophisticated system to regulate phosphate homeostasis over the course of evolution. However, due to the dependence of phosphate elimination on the kidney, humans with decreased kidney function are likely to be in a positive phosphate balance. Phosphate excess has been well recognized as a critical factor in the pathogenesis of mineral and bone disorders associated with chronic kidney disease, but recent investigations have also uncovered toxic effects of phosphate on the cardiovascular system and the aging process. Compelling evidence also suggests that increased fibroblastic growth factor 23 and parathyroid hormone levels in response to a positive phosphate balance contribute to adverse clinical outcomes. These insights support the current practice of managing serum phosphate in patients with advanced chronic kidney disease, although definitive evidence of these effects is lacking. Given the potential toxicity of excess phosphate, the general population may also be viewed as a target for phosphate management. However, the widespread implementation of dietary phosphate intervention in the general population may not be warranted due to the limited impact of increased phosphate intake on mineral metabolism and clinical outcomes. Nonetheless, the increasing incidence of kidney disease or injury in our aging society emphasizes the potential importance of this issue. Further work is needed to more completely characterize phosphate toxicity and to establish the optimal therapeutic strategy for managing phosphate in patients with chronic kidney disease and in the general population. Copyright © 2016 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

Calcium, magnesium, and phosphate abnormalities in the emergency department.

PubMed

Chang, Wan-Tsu W; Radin, Bethany; McCurdy, Michael T

2014-05-01

Derangements of calcium, magnesium, and phosphate are associated with increased morbidity and mortality. These minerals have vital roles in the cellular physiology of the neuromuscular and cardiovascular systems. This article describes the pathophysiology of these mineral disorders. It aims to provide the emergency practitioner with an overview of the diagnosis and management of these disorders. Copyright © 2014 Elsevier Inc. All rights reserved.

Homozygous ablation of fibroblast growth factor-23 results in hyperphosphatemia and impaired skeletogenesis, and reverses hypophosphatemia in Phex-deficient mice

PubMed Central

Sitara, Despina; Razzaque, Mohammed S.; Hesse, Martina; Yoganathan, Subbiah; Taguchi, Takashi; Erben, Reinhold G.; Jüppner, Harald; Lanske, Beate

2010-01-01

Fibroblast growth factor-23 (FGF-23), a recently identified molecule that is mutated in patients with autosomal dominant hypophosphatemic rickets (ADHR), appears to be involved in the regulation of phosphate homeostasis. Although increased levels of circulating FGF-23 were detected in patients with different phosphate-wasting disorders such as oncogenic osteomalacia (OOM) and X-linked hypophosphatemia (XLH), it is not yet clear whether FGF-23 is directly responsible for the abnormal regulation of mineral ion homeostasis and consequently bone development. To address some of these unresolved questions, we generated a mouse model, in which the entire Fgf-23 gene was replaced with the lacZ gene. Fgf-23 null (Fgf-23−/−) mice showed signs of growth retardation by day 17, developed severe hyperphosphatemia with elevated serum 1,25(OH)2D3 levels, and died by 13 weeks of age. Hyperphosphatemia in Fgf-23−/− mice was accompanied by skeletal abnormalities, as demonstrated by histological, molecular, and various other morphometric analyses. Fgf-23−/− mice had increased total-body bone mineral content (BMC) but decreased bone mineral density (BMD) of the limbs. Overall, Fgf-23−/− mice exhibited increased mineralization, but also accumulation of unmineralized osteoid leading to marked limb deformities. Moreover, Fgf-23−/− mice showed excessive mineralization in soft tissues, including heart and kidney. To further expand our understanding regarding the role of Fgf-23 in phosphate homeostasis and skeletal mineralization, we crossed Fgf-23−/− animals with Hyp mice, the murine equivalent of XLH. Interestingly, Hyp males lacking both Fgf-23 alleles were indistinguishable from Fgf-23−/− mice, both in terms of serum phosphate levels and skeletal changes, suggesting that Fgf-23 is upstream of the phosphate regulating gene with homologies to endopeptidases on the X chromosome (Phex) and that the increased plasma Fgf-23 levels in Hyp mice (and in XLH patients) may be at least partially responsible for the phosphate imbalance in this disorder. PMID:15579309

Calcium phosphate deposition rate, structure and osteoconductivity on electrospun poly(l-lactic acid) matrix using electrodeposition or simulated body fluid incubation

PubMed Central

He, Chuanglong; Jin, Xiaobing; Ma, Peter X.

2013-01-01

Mineralized nanofibrous scaffolds have been proposed as promising scaffolds for bone regeneration due to their ability to mimic both nanoscale architecture and chemical composition of natural bone extracellular matrix (ECM). In this study, a novel electrodeposition method was compared with an extensively explored simulated body fluid (SBF) incubation method in terms of the deposition rate, chemical composition, and morphology of calcium phosphate formed on electrospun fibrous thin matrices with a fiber diameter in the range from about 200 nm to about 1400 nm prepared using 6, 8, 10 and 12 wt% poly(l-lactic acid) (PLLA) solutions in a mixture of dichloromethane and acetone (2:1 in volume). The effects of the surface modification using the two mineralization techniques on osteoblastic cell (MC3T3-E1) proliferation and differentiation were also examined. It was found that electrodeposition was two to three orders of magnitude faster than the SBF method in mineralizing the fibrous matrices, reducing the mineralization time from about two weeks to an hour to achieve the same amounts of mineralization. The mineralization rate also varied with the fiber diameter but in opposite directions between the two mineralization methods. As a general trend, the increase of fiber diameter resulted in a faster mineralization rate for the electrodeposition method but a slower mineralization rate for the SBF incubation method. Using the electrodeposition method, one can control the chemical composition and morphology of the calcium phosphate by varying the electric deposition potential and electrolyte temperature to tune the mixture of dicalcium phosphate dihydrate (DCPD) and hydroxy apatite (HAp). Using the SBF method, one can only obtain a low crystallinity HAp. The mineralized electrospun PLLA fibrous matrices from either method similarly facilitate the proliferation and osteogenic differentiation of preosteoblastic MC3T3-E1 cells as compared to neat PLLA matrices. Therefore, the electrodeposition method can be utilized as a fast and versatile technique to fabricate mineralized nanofibrous scaffolds for bone tissue engineering. PMID:24012605

Biosorption and biomineralization of uranium(VI) by Saccharomyces cerevisiae-Crystal formation of chernikovite.

PubMed

Zheng, Xin-Yan; Wang, Xiao-Yu; Shen, Yang-Hao; Lu, Xia; Wang, Tie-Shan

2017-05-01

Biosorption of heavy metal elements including radionuclides by microorganisms is a promising and effective method for the remediation of the contaminated places. The responses of live Saccharomyces cerevisiae in the toxic uranium solutions during the biosorption process and the mechanism of uranium biomineralization by cells were investigated in the present study. A novel experimental phenomenon that uranium concentrations have negative correlation with pH values and positive correlation with phosphate concentrations in the supernatant was observed, indicating that hydrogen ions, phosphate ions and uranyl ions were involved in the chernikovite precipitation actively. During the biosorption process, live cells desorb deposited uranium within the equilibrium state of biosorption system was reached and the phosphorus concentration increased gradually in the supernatant. These metabolic detoxification behaviours could significantly alleviate uranium toxicity and protect the survival of the cells better in the environment. The results of microscopic and spectroscopic analysis demonstrated that the precipitate on the cell surface was a type of uranium-phosphate compound in the form of a scale-like substance, and S. cerevisiae could transform the uranium precipitate into crystalline state-tetragonal chernikovite [H 2 (UO 2 ) 2 (PO 4 ) 2 ·8H 2 O]. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of aqueous uranyl speciation on the kinetics of microbial uranium reduction

DOE PAGES

Belli, Keaton M.; DiChristina, Thomas J.; Van Cappellen, Philippe; ...

2015-02-16

The ability to predict the success of the microbial reduction of soluble U(VI) to highly insoluble U(IV) as an in situ bioremediation strategy is complicated by the wide range of geochemical conditions at contaminated sites and the strong influence of aqueous uranyl speciation on the bioavailability and toxicity of U(VI) to metal-reducing bacteria. In order to determine the effects of aqueous uranyl speciation on uranium bioreduction kinetics, incubations and viability assays with Shewanella putrefaciens strain 200 were conducted over a range of pH and dissolved inorganic carbon (DIC), Ca 2+, and Mg 2+ concentrations. A speciation-dependent kinetic model was developedmore » to reproduce the observed time series of total dissolved uranium concentration over the range of geochemical conditions tested. The kinetic model yielded the highest rate constant for the reduction of uranyl non-carbonate species (i.e., the ‘free’ hydrated uranyl ion, uranyl hydroxides, and other minor uranyl complexes), indicating that they represent the most readily reducible fraction of U(VI) despite being the least abundant uranyl species in solution. In the presence of DIC, Ca 2+, and Mg 2+ is suppressed during the formation of more bioavailable uranyl non-carbonate species and resulted in slower bioreduction rates. At high concentrations of bioavailable U(VI), however, uranium toxicity to S. putrefaciens inhibited bioreduction, and viability assays confirmed that the concentration of non-carbonate uranyl species best predicts the degree of toxicity. The effect of uranium toxicity was accounted for by incorporating the free ion activity model of metal toxicity into the bioreduction rate law. These results demonstrate that, in the absence of competing terminal electron acceptors, uranium bioreduction kinetics can be predicted over a wide range of geochemical conditions based on the bioavailability and toxicity imparted on U(VI) by solution composition. Finally, these findings also imply that the concentration of uranyl non-carbonate species, despite being extremely low, is a determining factor controlling uranium bioreduction at contaminated sites.« less

Density functional theory and molecular dynamics study of the uranyl ion (UO₂)²⁺.

PubMed

Rodríguez-Jeangros, Nicolás; Seminario, Jorge M

2014-03-01

The detection of uranium is very important, especially in water and, more importantly, in the form of uranyl ion (UO₂)²⁺, which is one of its most abundant moieties. Here, we report analyses and simulations of uranyl in water using ab initio modified force fields for water with improved parameters and charges of uranyl. We use a TIP4P model, which allows us to obtain accurate water properties such as the boiling point and the second and third shells of water molecules in the radial distribution function thanks to a fictitious charge that corrects the 3-point models by reproducing the exact dipole moment of the water molecule. We also introduced non-bonded interaction parameters for the water-uranyl intermolecular force field. Special care was taken in testing the effect of a range of uranyl charges on the structure of uranyl-water complexes. Atomic charges of the solvated ion in water were obtained using density functional theory (DFT) calculations taking into account the presence of nitrate ions in the solution, forming a neutral ensemble. DFT-based force fields were calculated in such a way that water properties, such as the boiling point or the pair distribution function stand. Finally, molecular dynamics simulations of a water box containing uranyl cations and nitrate anions are performed at room temperature. The three peaks in the oxygen-oxygen radial distribution function for water were found to be kept in the presence of uranyl thanks to the improvement of interaction parameters and charges. Also, we found three shells of water molecules surrounding the uranyl ion instead of two as was previously thought.

Uranium Release from Acidic Weathered Hanford Sediments: Single-Pass Flow-Through and Column Experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Guohui; Um, Wooyong; Wang, Zheming

The reaction of acidic radioactive waste with sediments can induce mineral transformation reactions that, in turn, control contaminant fate. Here, sediment weathering by synthetic uranium-containing acid solutions was investigated using bench-scale experiments to simulate waste disposal conditions at Hanford’s cribs, USA. During acid weathering, the presence of phosphate exerted a strong influence over uranium mineralogy and a rapidly precipitated, crystalline uranium phosphate phase (meta-ankoleite [K(UO2)(PO4)·3H2O]) was identified using spectroscopic and diffraction-based techniques. In phosphate-free system, uranium oxyhydroxide minerals such as K-compreignacite [K2(UO2)6O4(OH)6·7H2O] were formed. Single-pass flow-through (SPFT) and column leaching experiments using synthetic Hanford pore water showed that uranium precipitatedmore » as meta-ankoleite during acid weathering was strongly retained in the sediments, with an average release rate of 2.67E-12 mol g-1 s-1. In the absence of phosphate, uranium release was controlled by dissolution of uranium oxyhydroxide (compreignacite-type) mineral with a release rate of 1.05-2.42E-10 mol g-1 s-1. The uranium mineralogy and release rates determined for both systems in this study support the development of accurate U-release models for prediction of contaminant transport. These results suggest that phosphate minerals may be a good candidate for uranium remediation approaches at contaminated sites.« less

Uranium Release from Acidic Weathered Hanford Sediments: Single-Pass Flow-Through and Column Experiments.

PubMed

Wang, Guohui; Um, Wooyong; Wang, Zheming; Reinoso-Maset, Estela; Washton, Nancy M; Mueller, Karl T; Perdrial, Nicolas; O'Day, Peggy A; Chorover, Jon

2017-10-03

The reaction of acidic radioactive waste with sediments can induce mineral transformation reactions that, in turn, control contaminant fate. Here, sediment weathering by synthetic uranium-containing acid solutions was investigated using bench-scale experiments to simulate waste disposal conditions at Hanford's cribs (Hanford, WA). During acid weathering, the presence of phosphate exerted a strong influence over uranium mineralogy and a rapidly precipitated, crystalline uranium phosphate phase (meta-ankoleite [K(UO 2 )(PO 4 )·3H 2 O]) was identified using spectroscopic and diffraction-based techniques. In phosphate-free system, uranium oxyhydroxide minerals such as K-compreignacite [K 2 (UO 2 ) 6 O 4 (OH) 6 ·7H 2 O] were formed. Single-pass flow-through (SPFT) and column leaching experiments using synthetic Hanford pore water showed that uranium precipitated as meta-ankoleite during acid weathering was strongly retained in the sediments, with an average release rate of 2.67 × 10 -12 mol g -1 s -1 . In the absence of phosphate, uranium release was controlled by dissolution of uranium oxyhydroxide (compreignacite-type) mineral with a release rate of 1.05-2.42 × 10 -10 mol g -1 s -1 . The uranium mineralogy and release rates determined for both systems in this study support the development of accurate U-release models for the prediction of contaminant transport. These results suggest that phosphate minerals may be a good candidate for uranium remediation approaches at contaminated sites.

TRANSIENT AMORPHOUS CALCIUM PHOSPHATE IN FORMING ENAMEL

PubMed Central

Beniash, Elia; Metzler, Rebecca A.; Lam, Raymond S.K.; Gilbert, P.U.P.A.

2009-01-01

Enamel, the hardest tissue in the body, begins as a three-dimensional network of nanometer size mineral particles, suspended in a protein gel. This mineral network serves as a template for mature enamel formation. To further understand the mechanisms of enamel formation we characterized the forming enamel mineral at an early secretory stage using x-ray absorption near-edge structure (XANES) spectromicroscopy, transmission electron microscopy (TEM), FTIR microspectroscopy and polarized light microscopy. We show that the newly formed enamel mineral is amorphous calcium phosphate (ACP), which eventually transforms into apatitic crystals. Interestingly, the size, shape and spatial organization of these amorphous mineral particles and older crystals are essentially the same, indicating that the mineral morphology and organization in enamel is determined prior to its crystallization. Mineralization via transient amorphous phases has been previously reported in chiton teeth, mollusk shells, echinoderm spicules and spines, and recent reports strongly suggest the presence transient amorphous mineral in forming vertebrate bones. The present finding of transient ACP in murine tooth enamel suggests that this strategy might be universal. PMID:19217943

Phosphatase-mediated bioprecipitation of lead by soil fungi.

PubMed

Liang, Xinjin; Kierans, Martin; Ceci, Andrea; Hillier, Stephen; Gadd, Geoffrey Michael

2016-01-01

Geoactive soil fungi were examined for their ability to release inorganic phosphate (Pi ) and mediate lead bioprecipitation during growth on organic phosphate substrates. Aspergillus niger and Paecilomyces javanicus grew in 5 mM Pb(NO3)2-containing media amended with glycerol 2-phosphate (G2P) or phytic acid (PyA) as sole P sources, and liberated Pi into the medium. This resulted in almost complete removal of Pb from solution and extensive precipitation of lead-containing minerals around the biomass, confirming the importance of the mycelium as a reactive network for biomineralization. The minerals were identified as pyromorphite (Pb5(PO4)3Cl), only produced by P. javanicus, and lead oxalate (PbC2O4), produced by A. niger and P. javanicus. Geochemical modelling of lead and lead mineral speciation as a function of pH and oxalate closely correlated with experimental conditions and data. Two main lead biomineralization mechanisms were therefore distinguished: pyromorphite formation depending on organic phosphate hydrolysis and lead oxalate formation depending on oxalate excretion. This also indicated species specificity in biomineralization depending on nutrition and physiology. Our findings provide further understanding of lead geomycology and organic phosphates as a biomineralization substrate, and are also relevant to metal immobilization biotechnologies for bioremediation, metal and P biorecovery, and utilization of waste organic phosphates. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

State summaries: Idaho

USGS Publications Warehouse

Gillerman, V.S.; Weaver, M.J.; Bennett, E.H.

2006-01-01

According to the United States Geological Survey (USGS), Idaho's preliminary nonfuel mineral production value jumped to $893 million in 2005. Principal minerals by value included molybdenum concentrates, phosphate rock, sand and gravel, silver and portland cement. The state ranked second in phosphate and garnet production, third in silver and pumice, fourth in molybdenum concentrate production, and 21st overall. Majority of mining increases for the year were spurred by demand for metals by China's growing economy.

Mahlmoodite, FeZr(PO4).4H2O, a new iron zirconium phosphate mineral from Wilson Springs, Arkansas

USGS Publications Warehouse

Milton, C.; McGee, J.J.; Evans, H.T.

1993-01-01

Small (<0.5 mm) cream white spheres observed in V ore have been identified as ferrous zirconium phosphate tetrahedrate, FeZr(PO4)2.4H2O. This new mineral, named mahlmoodite, occurs as spherules of radiating fibers usually perched on crystals of pyroxene in vugs. The optical and crystallographic properties of mahlmoodite are described. -after Authors

Environmental benefits of using magnesium carbonate minerals as new wildfire retardants instead of commercially available, phosphate-based compounds.

PubMed

Liodakis, S; Tsoukala, M

2010-10-01

A serial batch leaching experiment has been carried out to evaluate the release of elements from the ash of Pinus halepensis needles burned under two test conditions-with and without treatment of the forest species with the carbonate minerals (huntite and hydromagnesite) in aqueous solution (pH 6). The ash (before and after leaching) and leachates were analyzed using atomic absorption spectroscopy and X-ray diffraction. Compared with data from samples treated with the commercially available, phosphate-based fire retardant diammonium phosphate (DAP), we found that use of huntite or hydromagnesite was much more successful in obstructing the release of the toxic elements present in the ash, probably because of the alkaline conditions resulting from decomposition of the minerals during burning. In contrast, DAP tended to be more able to facilitate the extraction of some toxic metals (e.g., Zn, Cu, Mn), probably because of the acidic conditions resulting from its decomposition to phosphoric acid. Data from this study thus lend strong support to the use of magnesium carbonate minerals as new wildfire retardants, because they were shown to be more friendly to the environment (e.g., soil, ground, and underground water streams) than those currently in use (e.g., phosphate or sulfate salt type).

Cleaving Off Uranyl Oxygens through Chelation: A Mechanistic Study in the Gas Phase

DOE PAGES

Abergel, Rebecca J.; de Jong, Wibe A.; Deblonde, Gauthier J. -P.; ...

2017-10-11

Recent efforts to activate the strong uranium-oxygen bonds in the dioxo uranyl cation have been limited to single oxo-group activation through either uranyl reduction and functionalization in solution, or by collision induced dissociation (CID) in the gas-phase, using mass spectrometry (MS). Here, we report and investigate the surprising double activation of uranyl by an organic ligand, 3,4,3-LI(CAM), leading to the formation of a formal U 6+ chelate in the gas-phase. The cleavage of both uranyl oxo bonds was experimentally evidence d by CID, using deuterium and 18O isotopic substitutions, and by infrared multiple photon dissociation (IRMPD) spectroscopy. Density functional theorymore » (DFT) computations predict that the overall reaction requires only 132 kJ/mol, with the first oxygen activation entailing about 107 kJ/mol. Here, combined with analysis of similar, but unreactive ligands, these results shed light on the chelation-driven mechanism of uranyl oxo bond cleavage, demonstrating its dependence on the presence of ligand hydroxyl protons available for direct interactions with the uranyl oxygens.« less

L-Myo-inositol 1-phosphate synthase in the aquatic fern Azolla filiculoides.

PubMed

Benaroya, Rony Oren; Zamski, Eli; Tel-Or, Elisha

2004-02-01

L-Myo-inositol 1-phosphate synthase (INPS EC 5.5.1.4) catalyzes the conversion of D-glucose 6-phosphate to L-myo-inositol 1-phosphate. INPS is a key enzyme involved in the biosynthesis of phytate which is a common form of stored phosphates in higher plants. The present study monitored the increase of INPS expression in Azolla filiculoides resulting from exposure to inorganic phosphates, metals and salt stress. The expression of INPS was significantly higher in Azolla plants that were grown in rich mineral growth medium than those maintained on nutritional growth medium. The expression of INPS protein and corresponding mRNA increased in plants cultured in minimal nutritional growth medium when phosphate or Zn2+, Cd2+ and NaCl were added to the growth medium. When employing rich mineral growth medium, INPS protein content increased with the addition of Zn2+, but decreased in the presence of Cd2+ and NaCl. These results indicated that accumulation of phytate in Azolla is a result of the intensified expression of INPS protein and mRNA, and its regulation may be primarily derived by the uptake of inorganic phosphate, and Zn2+, Cd2+ or NaCl.

Electrodeposition on nanofibrous polymer scaffolds: Rapid mineralization, tunable calcium phosphate composition and topography

PubMed Central

He, Chuanglong; Xiao, Guiyong; Jin, Xiaobing; Sun, Chenghui; Ma, Peter X.

2011-01-01

We developed a straightforward, fast, and versatile technique to fabricate mineralized nanofibrous polymer scaffolds for bone regeneration in this work. Nanofibrous poly(l-lactic acid) scaffolds were fabricated using both electrospinning and phase separation techniques. An electrodeposition process was designed to deposit calcium phosphate on the nanofibrous scaffolds. Such scaffolds contain a high quality mineral coating on the fiber surface with tunable surface topography and chemical composition by varying the processing parameters, which can mimic the composition and structure of natural bone extracellular matrix and provide a more biocompatible interface for bone regeneration. PMID:21673827

The investigations of changes in mineral-organic and carbon-phosphate ratios in the mixed saliva by synchrotron infrared spectroscopy

NASA Astrophysics Data System (ADS)

Seredin, Pavel; Goloshchapov, Dmitry; Kashkarov, Vladimir; Ippolitov, Yuri; Bambery, Keith

The objective of this study was to investigate the efficiency of the saturation of mixed saliva by mineral complexes and groups necessary for the remineralisation of tooth enamel using exogenous and endogenous methods of caries prevention. Using IR spectroscopy and high-intensity synchrotron radiation, changes in the composition of the human mixed saliva were identified when exogenous and endogenous methods of caries prevention are employed. Based on the calculations of mineral/organic and carbon/phosphate ratios, changes in the composition of the human mixed saliva depending on a certain type of prevention were identified. It is shown that the use of a toothpaste (exogenous prevention) alone based on a multi-mineral complex including calcium glycerophosphate provides only a short-term effect of saturating the oral cavity with mineral complexes and groups. Rinsing of the oral cavity with water following the preventive use of a toothpaste completely removes the effect of the saturation of the mixed saliva with mineral groups and complexes. The use of tablets of a multi-mineral complex with calcium glycerophosphate (endogenous prevention) in combination with exogenous prevention causes an average increase of ∼10% in the content of mineral groups and complexes in the mixed saliva and allows long-term saturation of the oral fluid by them. This method outperforms the exogenous one owing to a long-term effect of optimal concentrations of endogenous and biologically available derivatives of phosphates on the enamel surface.

EXTRACTION OF URANYL NITRATE FROM AQUEOUS SOLUTIONS

DOEpatents

Furman, N.H.; Mundy, R.J.

1957-12-10

An improvement in the process is described for extracting aqueous uranyl nitrate solutions with an organic solvent such as ether. It has been found that the organic phase will extract a larger quantity of uranyl nitrate if the aqueous phase contains in addition to the uranyl nitrate, a quantity of some other soluble nitrate to act as a salting out agent. Mentioned as suitable are the nitrates of lithium, calcium, zinc, bivalent copper, and trivalent iron.

Mobility of rare earth elements in mine drainage: Influence of iron oxides, carbonates, and phosphates.

PubMed

Edahbi, Mohamed; Plante, Benoît; Benzaazoua, Mostafa; Ward, Matthew; Pelletier, Mia

2018-05-01

The geochemical behavior of rare earth elements (REE) was investigated using weathering cells. The influence of sorption and precipitation on dissolved REE mobility and fractionation is evaluated using synthetic iron-oxides, carbonates, and phosphates. Sorption cell tests are conducted on the main lithologies of the expected waste rocks from the Montviel deposit. The sorbed materials are characterized using a scanning electron microscope (SEM) equipped with a microanalysis system (energy dispersive spectroscopy EDS) (SEM-EDS), X-ray diffraction (XRD), and X-ray absorption near edge structure (XANES) in order to understand the effect of the synthetic minerals on REE mobility. The results confirm that sorption and precipitation control the mobility and fractionation of REE. The main sorbent phases are the carbonates, phosphates (present as accessory minerals in the Montviel waste rocks), and iron oxides (main secondary minerals generated upon weathering of the Montviel lithologies). The XANES results show that REE are present as trivalent species after weathering. Thermodynamic equilibrium calculations results using Visual Minteq suggest that REE could precipitate as secondary phosphates (REEPO 4 ). Copyright © 2018 Elsevier Ltd. All rights reserved.

Concentration of simple aldehydes by sulfite-containing double-layer hydroxide minerals: implications for biopoesis

NASA Technical Reports Server (NTRS)

Pitsch, S.; Krishnamurthy, R.; Arrhenius, G.; Bada, J. L. (Principal Investigator)

2000-01-01

Environmental conditions play an important role in conceptual studies of prebiotically relevant chemical reactions that could have led to functional biomolecules. The necessary source compounds are likely to have been present in dilute solution, raising the question of how to achieve selective concentration and to reach activation. With the assumption of an initial 'RNA World', the questions of production, concentration, and interaction of aldehydes and aldehyde phosphates, potential precursors of sugar phosphates, come into the foreground. As a possible concentration process for simple, uncharged aldehydes, we investigated their adduct formation with sulfite ion bound in the interlayer of positively charged expanding-sheet-structure double-layer hydroxide minerals. Minerals of this type, initially with chloride as interlayer counter anion, have previously been shown to induce concentration and subsequent aldolization of aldehyde phosphates to form tetrose, pentose, and hexose phosphates. The reversible uptake of the simple aldehydes formaldehyde, glycolaldehyde, and glyceraldehyde by adduct formation with the immobilized sulfite ions is characterized by equilibrium constants of K=1.5, 9, and 11, respectively. This translates into an observable uptake at concentrations exceeding 50 mM.

Production and Characterization of Desmalonichrome Relative Binding Affinity for Uranyl Ions in Relation to Other Siderophores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mo, Kai-For; Dai, Ziyu; Wunschel, David S.

2016-06-24

Siderophores are Fe binding secondary metabolites that have been investigated for their uranium binding properties. Much of the previous work has focused on characterizing hydroxamate types of siderophores, such as desferrioxamine B, for their uranyl binding affinity. Carboxylate forms of these metabolites hold potential to be more efficient chelators of uranyl, yet they have not been widely studied and are more difficult to obtain. Desmalonichrome is a carboxylate siderophore which is not commercially available and so was obtained from the ascomycete fungus Fusarium oxysporum cultivated under Fe depleted conditions. The relative affinity for uranyl binding of desmalonichrome was investigated usingmore » a competitive analysis of binding affinities between uranyl acetate and different concentrations of iron(III) chloride using electrospray ionization mass spectrometry (ESI-MS). In addition to desmalonichrome, three other siderophores, including two hydroxamates (desferrioxamine B and desferrichrome) and one carboxylate (desferrichrome A) were studied to understand their relative affinities for the uranyl ion at two pH values. The binding affinities of hydroxymate siderophores to uranyl ion were found to decrease to a greater degree at lower pH as the concentration of Fe (III) ion increases. On the other hand, lowering pH has little impact on the binding affinities between carboxylate siderophores and uranyl ion. Desmalonichrome was shown to have the greatest relative affinity for uranyl at any pH and Fe(III) concentration. These results suggest that acidic functional groups in the ligands are critical for strong chelation with uranium at lower pH.« less

A Uranyl Peroxide Dimer in the Gas Phase

DOE PAGES

Dau, Phuong D.; Dau, Phuong V.; Rao, Linfeng; ...

2017-03-14

For this study, the gas-phase uranyl peroxide dimer, [(UO 2) 2(O2)(L) 2] 2+ where L = 2,2'-trifluoroethylazanediyl)bis(N,N'-dimethylacetamide), was synthesized by electrospray ionization of a solution of UO 2 2+ and L. Collision-induced dissociation of this dimer resulted in endothermic O atom elimination to give [(UO 2) 2(O)(L) 2] 2+, which was found to spontaneously react with water via exothermic hydrolytic chemisorption to yield [(UO 2) 2(OH) 2(L) 2] 2+. Density functional theory computations of the energies for the gas-phase reactions are in accord with observations. The structures of the observed uranyl dimer were computed, with that of the peroxide ofmore » particular interest, as a basis to evaluate the formation of condensed phase uranyl peroxides with bent structures. The computed dihedral angle in [(UO 2) 2(O 2)(L) 2] 2+ is 145°, indicating a substantial deviation from the planar structure with a dihedral angle of 180°. Energies needed to induce bending in the most elementary gas-phase uranyl peroxide complex, [(UO 2) 2(O 2)] 2+, were computed. It was found that bending from the lowest-energy planar structure to dihedral angles up to 140° required energies of <10 kJ/mol. The gas-phase results demonstrate the inherent stability of the uranyl peroxide moiety and support the notion that the uranyl-peroxide-uranyl structural unit is intrinsically planar, with only minor energy perturbations needed to form the bent structures found in studtite and uranyl peroxide nanostructures.« less

Precipitation of Phosphate Minerals by Microorganisms Isolated from a Fixed-Biofilm Reactor Used for the Treatment of Domestic Wastewater

PubMed Central

Rivadeneyra, Almudena; Gonzalez-Martinez, Alejandro; Gonzalez-Lopez, Jesus; Martin-Ramos, Daniel; Martinez-Toledo, Maria Victoria; Rivadeneyra, Maria Angustias

2014-01-01

The ability of bacteria isolated from a fixed-film bioreactor to precipitate phosphate crystals for the treatment of domestic wastewater in both artificial and natural media was studied. When this was demonstrated in artificial solid media for crystal formation, precipitation took place rapidly, and crystal formation began 3 days after inoculation. The percentage of phosphate-forming bacteria was slightly higher than 75%. Twelve major colonies with phosphate precipitation capacity were the dominant heterotrophic platable bacteria growing aerobically in artificial media. According to their taxonomic affiliations (based on partial sequencing of the 16S rRNA), the 12 strains belonged to the following genera of Gram-negative bacteria: Rhodobacter, Pseudoxanthobacter, Escherichia, Alcaligenes, Roseobacter, Ochrobactrum, Agromyce, Sphingomonas and Paracoccus. The phylogenetic tree shows that most of the identified populations were evolutionarily related to the Alphaproteobacteria (91.66% of sequences). The minerals formed were studied by X-ray diffraction, scanning electron microscopy (SEM), and energy dispersive X-ray microanalysis (EDX). All of these strains formed phosphate crystals and precipitated struvite (MgNH4PO4·6H2O), bobierrite [Mg3(PO4)2·8H2O] and baricite [(MgFe)3(PO4)2·8H2O]. The results obtained in this study show that struvite and spherulite crystals did not show any cell marks. Moreover, phosphate precipitation was observed in the bacterial mass but also near the colonies. Our results suggest that the microbial population contributed to phosphate precipitation by changing the media as a consequence of their metabolic activity. Moreover, the results of this research suggest that bacteria play an active role in the mineral precipitation of soluble phosphate from urban wastewater in submerged fixed-film bioreactors. PMID:24699031

URANIUM PURIFICATION PROCESS

DOEpatents

Ruhoff, J.R.; Winters, C.E.

1957-11-12

A process is described for the purification of uranyl nitrate by an extraction process. A solution is formed consisting of uranyl nitrate, together with the associated impurities arising from the HNO/sub 3/ leaching of the ore, in an organic solvent such as ether. If this were back extracted with water to remove the impurities, large quantities of uranyl nitrate will also be extracted and lost. To prevent this, the impure organic solution is extracted with small amounts of saturated aqueous solutions of uranyl nitrate thereby effectively accomplishing the removal of impurities while not allowing any further extraction of the uranyl nitrate from the organic solvent. After the impurities have been removed, the uranium values are extracted with large quantities of water.

43 CFR 3504.21 - What are the minimum royalty rates?

Code of Federal Regulations, 2012 CFR

2012-10-01

... or phosphate rock and associated or related minerals. (b) Sodium 2% of the quantity or gross value of... LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LEASING OF SOLID MINERALS OTHER... the point of shipment to market. (e) Gilsonite No minimum royalty rate. (f) Hardrock Minerals No...

43 CFR 3504.21 - What are the minimum royalty rates?

Code of Federal Regulations, 2014 CFR

2014-10-01

... or phosphate rock and associated or related minerals. (b) Sodium 2% of the quantity or gross value of... LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LEASING OF SOLID MINERALS OTHER... the point of shipment to market. (e) Gilsonite No minimum royalty rate. (f) Hardrock Minerals No...

43 CFR 3504.21 - What are the minimum royalty rates?

Code of Federal Regulations, 2013 CFR

2013-10-01

... or phosphate rock and associated or related minerals. (b) Sodium 2% of the quantity or gross value of... LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LEASING OF SOLID MINERALS OTHER... the point of shipment to market. (e) Gilsonite No minimum royalty rate. (f) Hardrock Minerals No...

43 CFR 3504.21 - What are the minimum royalty rates?

Code of Federal Regulations, 2011 CFR

2011-10-01

... or phosphate rock and associated or related minerals. (b) Sodium 2% of the quantity or gross value of... LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LEASING OF SOLID MINERALS OTHER... the point of shipment to market. (e) Gilsonite No minimum royalty rate. (f) Hardrock Minerals No...

A Solution-Based Approach for Mo-99 Production: Considerations for Nitrate versus Sulfate Media

DOE PAGES

Youker, Amanda J.; Chemerisov, Sergey D.; Kalensky, Michael; ...

2013-01-01

Molybdenum-99 is the parent of Technetium-99m, which is used in nearly 80% of all nuclear medicine procedures. The medical community has been plagued by Mo-99 shortages due to aging reactors, such as the NRU (National Research Universal) reactor in Canada. There are currently no US producers of Mo-99, and NRU is scheduled for shutdown in 2016, which means that another Mo-99 shortage is imminent unless a potential domestic Mo-99 producer fills the void. Argonne National Laboratory is assisting two potential domestic suppliers of Mo-99 by examining the effects of a uranyl nitrate versus a uranyl sulfate target solution configuration onmore » Mo-99 production. Uranyl nitrate solutions are easier to prepare and do not generate detectable amounts of peroxide upon irradiation, but a high radiation field can lead to a large increase in pH, which can lead to the precipitation of fission products and uranyl hydroxides. Uranyl sulfate solutions are more difficult to prepare, and enough peroxide is generated during irradiation to cause precipitation of uranyl peroxide, but this can be prevented by adding a catalyst to the solution. A titania sorbent can be used to recover Mo-99 from a highly concentrated uranyl nitrate or uranyl sulfate solution; however, different approaches must be taken to prevent precipitation during Mo-99 production.« less

Calcium-phosphate biomineralization induced by alkaline phosphatase activity in Escherichia coli: localization, kinetics and potential signatures in the fossil record

NASA Astrophysics Data System (ADS)

Cosmidis, Julie; Benzerara, Karim; Guyot, François; Skouri-Panet, Fériel; Duprat, Elodie; Férard, Céline; Guigner, Jean-Michel; Babonneau, Florence; Coelho, Cristina

2015-12-01

Bacteria are thought to play an important role in the formation of calcium-phosphate minerals composing marine phosphorites, as supported by the common occurrence of fossil microbes in these rocks. Phosphatase enzymes may play a key role in this process. Indeed, they may increase the supersaturation with respect to Ca-phosphates by releasing orthophosphate ions following hydrolysis of organic phosphorus. However, several questions remain unanswered about the cellular-level mechanisms involved in this model, and its potential signatures in the mineral products. We studied Ca-phosphate precipitation by different strains of Escherichia coli which were genetically modified to differ in the abundance and cellular localization of the alkaline phosphatase (PHO A) produced. The mineral precipitated by either E. coli or purified PHO A was invariably identified as a carbonate-free non-stoichiometric hydroxyapatite. However, the bacterial precipitates could be discriminated from the ones formed by purified PHO A at the nano-scale. PHO A localization was shown to influence the pattern of Ca-phosphate nucleation and growth. Finally, the rate of calcification was proved to be consistent with the PHO A enzyme kinetics. Overall, this study provides mechanistic keys to better understand phosphogenesis in the environment, and experimental references to better interpret the microbial fossil record in phosphorites.

Mineral induced formation of pentose-2,4-bisphosphates

NASA Technical Reports Server (NTRS)

Krishnamurthy, R.; Pitsch, S.; Arrhenius, G.; Bada, J. L. (Principal Investigator)

1999-01-01

Formation of rac.-pentose-2,4-bisphosphates is demonstrated, starting from glycolaldehyde phosphate and glyceraldehyde-2-phosphate, and induced by mixed valence double layer metal hydroxide minerals. The reactions proceed from dilute aqueous reactant solutions (1.5 mM) at near neutral pH. Conditions have been established, where ribose-2,4-bisphosphate is the major product (approximately 48%) among the pentose-2,4-bisphosphates, which are formed with up to 25% yield.

Petro-mineralogical Studies of the Paleoproterozoic Phosphorites in the Sonrai basin, Lalitpur District, Uttar Pradesh, India

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dar, Shamim A., E-mail: sjshamim@gmail.com; Khan, K. F.; Khan, Saif A.

2015-09-15

The Paleoproterozoic phosphorites constitute an economically significant component of the Sonrai basin of Lalitpur district. These are associated with ferruginous shale, ironstone, limestone and quartz breccia. Petro-mineralogical studies of samples of the phosphorites, using X-ray diffractometry and scanning electron microscopy, reveal that the collophane (carbonate-fluorapatite) is the dominant phosphate mineral. Calcite, dolomite, quartz, mica and haematite are the dominant gangue constituents. The phosphate minerals occur as oolites mutually replaced by carbonate and silica. The presence of iron oxides has been found in most of the thin sections. There is meagre evidence of organic matter in the form of filaments ofmore » microbial phosphate laminae in the samples of phosphorite. The mineral assemblages, their texture and various forms in these phosphorites may be due to some environmental vicissitudes followed by replacement processes and biogenic activities.« less

Calixarene cleansing formulation for uranium skin contamination.

PubMed

Phan, Guillaume; Semili, Naïma; Bouvier-Capely, Céline; Landon, Géraldine; Mekhloufi, Ghozlene; Huang, Nicolas; Rebière, François; Agarande, Michelle; Fattal, Elias

2013-10-01

An oil-in-water cleansing emulsion containing calixarene molecule, an actinide specific chelating agent, was formulated in order to improve the decontamination of uranium from the skin. Commonly commercialized cosmetic ingredients such as surfactants, mineral oil, or viscosifying agents were used in preparing the calixarene emulsion. The formulation was characterized in terms of size and apparent viscosity measurements and then was tested for its ability to limit uranyl ion permeation through excoriated pig-ear skin explants in 24-h penetration studies. Calixarene emulsion effectiveness was compared with two other reference treatments consisting of DTPA and EHBP solutions. Application of calixarene emulsion induced the highest decontamination effect with an 87% decrease in uranium diffusion flux. By contrast, EHBP and DTPA solutions only allowed a 50% and 55% reduction of uranium permeation, respectively, and had the same effect as a simple dilution of the contamination by pure water. Uranium diffusion decrease was attributed to uranyl ion-specific chelation by calixarene within the formulation, since no significant effect was obtained after application of the same emulsion without calixarene. Thus, calixarene cleansing emulsion could be considered as a promising treatment in case of accidental contamination of the skin by highly diffusible uranium compounds.

Alterations in mineral properties of zebrafish skeletal bone induced by liliput dtc232 gene mutation

NASA Astrophysics Data System (ADS)

Wang, Xiu-Mei; Cui, Fu-Zhai; Ge, Jun; Ma, Chen

2003-11-01

The alterations of mineral properties of bone by gene mutation in the zebrafish, which is associated with abnormal bone mineralization and bone diseases, were reported for the first time in this paper. Transmission electron microscope (TEM), Fourier transform infrared microspectroscopy (FTIRM) and thermogravimetric analysis (TGA) were used to investigate the changes in the mineral. Significant variations of the morphologies of the minerals and the mineral/matrix ratio after liliputdtc232(lil) gene mutation have been observed. The morphologies of the minerals, examined by TEM, revealed that the mutated mineral was in bigger size and the shape was block shaped but not plate shaped. The results of FTIRM indicated that the lil mutant zebrafish skeleton exhibited a greater mineral/matrix ratio (phosphate/matrix=4.86±0.28) than that of wild-type zebrafish bone (phosphate/matrix=4.17±0.67), which was confirmed by TGA analysis. Furthermore, the mineral of lil bone became less mature and crystalline with more ion substitutions. And the selected areas electron diffraction (SAED) patterns showed that the main crystal phases of the two type fishes were both hydroxyapatite. In addition, we have discussed the relationship among the mineral properties, nanomechanical properties and biomineralization process.

Studies on the protective effect of dietary fish oil on uranyl-nitrate-induced nephrotoxicity and oxidative damage in rat kidney.

PubMed

Priyamvada, Shubha; Khan, Sara A; Khan, Md Wasim; Khan, Sheeba; Farooq, Neelam; Khan, Farah; Yusufi, A N K

2010-01-01

Human and animal exposure demonstrates that uranium is nephrotoxic. However, attempts to reduce it were not found suitable for clinical use. Dietary fish oil (FO) enriched in omega-3 fatty acids reduces the severity of cardiovascular and renal diseases. Present study investigates the protective effect of FO on uranyl nitrate (UN)-induced renal damage. Rats prefed with experimental diets for 15 days, given single nephrotoxic dose of UN (0.5mg/kg body weight) intraperitoneally. After 5d of UN treatment, serum/urine parameters, enzymes of carbohydrate metabolism, brush border membrane (BBM), oxidative stress and phosphate transport were analyzed in rat kidney. UN nephrotoxicity was characterized by increased serum creatinine and blood urea nitrogen. UN increased the activity of lactate dehydrogenase and NADP-malic enzyme whereas decreased malate, isocitrate and glucose-6-phophate dehydrogenases; glucose-6-phophatase, fructose-1, 6-bisphosphatase and BBM enzyme activities. UN caused oxidant/antioxidant imbalances as reflected by increased lipid peroxidation, activities of superoxide dismutase, glutathione peroxidase and decreased catalase activity. Feeding FO alone increased activities of enzymes of glucose metabolism, BBM, oxidative stress and Pi transport. UN-elicited alterations were prevented by FO feeding. However, corn oil had no such effects and was not similarly effective. In conclusion, FO appears to protect against UN-induced nephrotoxicity by improving energy metabolism and antioxidant defense mechanism. Copyright 2009 Elsevier Ltd. All rights reserved.

Different biosorption mechanisms of Uranium(VI) by live and heat-killed Saccharomyces cerevisiae under environmentally relevant conditions.

PubMed

Wang, Tieshan; Zheng, Xinyan; Wang, Xiaoyu; Lu, Xia; Shen, Yanghao

2017-02-01

Uranium adsorption mechanisms of live and heat-killed Saccharomyces cerevisiae in different pH values and biomass concentrations were studied under environmentally relevant conditions. Compared with live cells, the adsorption capacity of heat-killed cells is almost one order of magnitude higher in low biomass concentration and highly acidic pH conditions. To explore the mesoscopic surface interactions between uranium and cells, the characteristic of uranium deposition was investigated by SEM-EDX, XPS and FTIR. Biosorption process of live cells was considered to be metabolism-dependent. Under stimulation by uranyl ions, live cells could gradually release phosphorus and reduce uranium from U(VI) to U(IV) to alleviate uranium toxicity. The uranyl-phosphate complexes were formed in scale-like shapes on cell surface. The metabolic detoxification mechanisms such as reduction and "self-protection" are of significance to the migration of radionuclides. In the metabolism-independent biosorption process of heat-killed cells: the cells cytomembrane was damaged by autoclaving which led to the free diffusion of phosphorous from intracellular, and the rough surface and nano-holes indicated that the dead cells provided larger contact area to precipitate U(VI) as spherical nano-particles. The high biosorption capacity of heat-killed cells makes it become a suitable biological adsorbent for uranium removal. Copyright © 2016 Elsevier Ltd. All rights reserved.

SEPARATION OF FISSION PRODUCT VALUES FROM THE HEXAVALENT PLUTONIUM BY CARRIER PRECIPITATION

DOEpatents

Davies, T.H.

1959-12-15

An improved precipitation of fission products on bismuth phosphate from an aqueous mineral acid solution also containing hexavalent plutonium by incorporating, prior to bismuth phosphate precipitation, from 0.05 to 2.5 grams/ liter of zirconium phosphate, niobium oxide. and/or lanthanum fluoride is described. The plutonium remains in solution.

Phosphate homeostasis and its role in bone health.

PubMed

Penido, Maria Goretti M G; Alon, Uri S

2012-11-01

Phosphate is one of the most abundant minerals in the body, and its serum levels are regulated by a complex set of processes occurring in the intestine, skeleton, and kidneys. The currently known main regulators of phosphate homeostasis include parathyroid hormone (PTH), calcitriol, and a number of peptides collectively known as the "phosphatonins" of which fibroblast growth factor-23 (FGF-23) has been best defined. Maintenance of extracellular and intracellular phosphate levels within a narrow range is important for many biological processes, including energy metabolism, cell signaling, regulation of protein synthesis, skeletal development, and bone integrity. The presence of adequate amounts of phosphate is critical for the process of apoptosis of mature chondrocytes in the growth plate. Without the presence of this mineral in high enough quantities, chondrocytes will not go into apoptosis, and the normal physiological chain of events that includes invasion of blood vessels and the generation of new bone will be blocked, resulting in rickets and delayed growth. In the rest of the skeleton, hypophosphatemia will result in osteomalacia due to an insufficient formation of hydroxyapatite. This review will address phosphate metabolism and its role in bone health.

Effect of phosphate treatment of Acid-etched implants on mineral apposition rates near implants in a dog model.

PubMed

Foley, Christine Hyon; Kerns, David G; Hallmon, William W; Rivera-Hidalgo, Francisco; Nelson, Carl J; Spears, Robert; Dechow, Paul C; Opperman, Lynne A

2010-01-01

This study evaluated the effects of phosphate coating of acid-etched titanium on the mineral apposition rate (MAR) and new bone-to-implant contact (BIC) in a canine model. Titanium implants (2.2 3 4 mm) with acid-etched surfaces that were electrolytically phosphated or not were placed in 48 mandibular sites in six foxhounds. Tetracycline and calcein dyes were administered 1 week after implant placement and 1 week before sacrifice. At 12 weeks after implant placement, the animals were sacrificed. MAR and BIC were evaluated using fluorescence microscopy. Light microscopic and histologic evaluations were performed on undecalcified sections. Microscopic evaluation showed the presence of healthy osteoblasts lining bone surfaces near implants. Similar BIC was observed in phosphated and nonphosphated titanium implant sites. MAR was significantly higher around the nonphosphated titanium implant surfaces than around the phosphated titanium samples. No significant differences were found between dogs or implant sites. Acid-etched implants showed significantly higher MARs compared to acid-etched, phosphate-coated implants. Int J Maxillofac Implants 2010;25:278-286.

Osteo-Renal Regulation of Systemic Phosphate Metabolism

PubMed Central

Razzaque, Mohammed Shawkat

2011-01-01

Summary Impaired kidney function and subsequent skeletal responses play a critical role in disrupting phosphate balance in chronic kidney disease (CKD) patients with mineral and bone disorder (CKD-MBD). In patients with CKD-MBD, the inability of the kidney to maintain normal mineral ion balance affects bone remodeling to induce skeletal fracture and extraskeletal vascular calcification. In physiological conditions, bone-derived fibroblast growth factor 23 (FGF23) acts on the kidney to reduce serum phosphate and 1,25-dihydroxyvitamin D levels. In humans, increased bioactivity of FGF23 leads to increased urinary phosphate excretion, which induces hypophosphatemic diseases (e.g., rickets/osteomalacia). However, reduced FGF23 activity is associated with hyperphosphatemic diseases (e.g., tumoral calcinosis). In patients with CKD, high serum levels of FGF23 fail to reduce serum phosphate levels and lead to numerous complications, including vascular calcification, one of the important determinants of mortality of CKD-MBD patients. Of particular significance, molecular, biochemical and morphological changes in patients with CKD-MBD are mostly due to osteo-renal dysregulation of mineral ion metabolism. Furthermore, hyperphosphatemia can partly contribute to the development of secondary hyperparathyroidism in patients with CKD-MBD. Relatively new pharmacological agents including sevelamer hydrochloride, calcitriol analogs and cinacalcet hydrochloride are used either alone, or in combination, to minimize hyperphosphatemia and hyperparathyroidism associated complications to improve morbidity and mortality of CKD-MBD patients. This article will briefly summarize how osteo-renal miscommunication can induce phosphate toxicity, resulting in extensive tissue injuries. PMID:21438115

Osteo-renal regulation of systemic phosphate metabolism.

PubMed

Razzaque, Mohammed Shawkat

2011-04-01

Impaired kidney function and subsequent skeletal responses play a critical role in disrupting phosphate balance in chronic kidney disease (CKD) patients with mineral and bone disorder (CKD-MBD). In patients with CKD-MBD, the inability of the kidney to maintain normal mineral ion balance affects bone remodeling to induce skeletal fracture and extraskeletal vascular calcification. In physiological conditions, bone-derived fibroblast growth factor 23 (FGF23) acts on the kidney to reduce serum phosphate and 1,25-dihydroxyvitamin D levels. In humans, increased bioactivity of FGF23 leads to increased urinary phosphate excretion, which induces hypophosphatemic diseases (e.g., rickets/osteomalacia). However, reduced FGF23 activity is associated with hyperphosphatemic diseases (e.g., tumoral calcinosis). In patients with CKD, high serum levels of FGF23 fail to reduce serum phosphate levels and lead to numerous complications, including vascular calcification, one of the important determinants of mortality of CKD-MBD patients. Of particular significance, molecular, biochemical and morphological changes in patients with CKD-MBD are mostly due to osteo-renal dysregulation of mineral ion metabolism. Furthermore, hyperphosphatemia can partly contribute to the development of secondary hyperparathyroidism in patients with CKD-MBD. Relatively new pharmacological agents including sevelamer hydrochloride, calcitriol analogs and cinacalcet hydrochloride are used either alone, or in combination, to minimize hyperphosphatemia and hyperparathyroidism associated complications to improve morbidity and mortality of CKD-MBD patients. This article will briefly summarize how osteo-renal miscommunication can induce phosphate toxicity, resulting in extensive tissue injuries. Copyright © 2011 Wiley Periodicals, Inc.

Integration of P, S, Fe, and Zn nutrition signals in Arabidopsis thaliana: potential involvement of PHOSPHATE STARVATION RESPONSE 1 (PHR1)

PubMed Central

Briat, Jean-François; Rouached, Hatem; Tissot, Nicolas; Gaymard, Frédéric; Dubos, Christian

2015-01-01

Phosphate and sulfate are essential macro-elements for plant growth and development, and deficiencies in these mineral elements alter many metabolic functions. Nutritional constraints are not restricted to macro-elements. Essential metals such as zinc and iron have their homeostasis strictly genetically controlled, and deficiency or excess of these micro-elements can generate major physiological disorders, also impacting plant growth and development. Phosphate and sulfate on one hand, and zinc and iron on the other hand, are known to interact. These interactions have been partly described at the molecular and physiological levels, and are reviewed here. Furthermore the two macro-elements phosphate and sulfate not only interact between themselves but also influence zinc and iron nutrition. These intricated nutritional cross-talks are presented. The responses of plants to phosphorus, sulfur, zinc, or iron deficiencies have been widely studied considering each element separately, and some molecular actors of these regulations have been characterized in detail. Although some scarce reports have started to examine the interaction of these mineral elements two by two, a more complex analysis of the interactions and cross-talks between the signaling pathways integrating the homeostasis of these various elements is still lacking. However, a MYB-like transcription factor, PHOSPHATE STARVATION RESPONSE 1, emerges as a common regulator of phosphate, sulfate, zinc, and iron homeostasis, and its role as a potential general integrator for the control of mineral nutrition is discussed. PMID:25972885

Targeted ablation of Fgf23 demonstrates an essential physiological role of FGF23 in phosphate and vitamin D metabolism

PubMed Central

Shimada, Takashi; Kakitani, Makoto; Yamazaki, Yuji; Hasegawa, Hisashi; Takeuchi, Yasuhiro; Fujita, Toshiro; Fukumoto, Seiji; Tomizuka, Kazuma; Yamashita, Takeyoshi

2004-01-01

Inorganic phosphate is essential for ECM mineralization and also as a constituent of important molecules in cellular metabolism. Investigations of several hypophosphatemic diseases indicated that a hormone-like molecule probably regulates serum phosphate concentration. FGF23 has recently been recognized as playing important pathophysiological roles in several hypophosphatemic diseases. We present here the evidence that FGF23 is a physiological regulator of serum phosphate and 1,25-dihydroxyvitamin D (1,25[OH]2D) by generating FGF23-null mice. Disruption of the Fgf23 gene did not result in embryonic lethality, although homozygous mice showed severe growth retardation with abnormal bone phenotype and markedly short life span. The Fgf23–/– mice displayed significantly high serum phosphate with increased renal phosphate reabsorption. They also showed an elevation in serum 1,25(OH)2D that was due to the enhanced expression of renal 25-hydroxyvitamin D-1α-hydroxylase (1α-OHase) from 10 days of age. These phenotypes could not be explained by currently known regulators of mineral homeostasis, indicating that FGF23 is essential for normal phosphate and vitamin D metabolism. PMID:14966565

Targeted ablation of Fgf23 demonstrates an essential physiological role of FGF23 in phosphate and vitamin D metabolism.

PubMed

Shimada, Takashi; Kakitani, Makoto; Yamazaki, Yuji; Hasegawa, Hisashi; Takeuchi, Yasuhiro; Fujita, Toshiro; Fukumoto, Seiji; Tomizuka, Kazuma; Yamashita, Takeyoshi

2004-02-01

Inorganic phosphate is essential for ECM mineralization and also as a constituent of important molecules in cellular metabolism. Investigations of several hypophosphatemic diseases indicated that a hormone-like molecule probably regulates serum phosphate concentration. FGF23 has recently been recognized as playing important pathophysiological roles in several hypophosphatemic diseases. We present here the evidence that FGF23 is a physiological regulator of serum phosphate and 1,25-dihydroxyvitamin D (1,25[OH]2D) by generating FGF23-null mice. Disruption of the Fgf23 gene did not result in embryonic lethality, although homozygous mice showed severe growth retardation with abnormal bone phenotype and markedly short life span. The Fgf23(-/-) mice displayed significantly high serum phosphate with increased renal phosphate reabsorption. They also showed an elevation in serum 1,25(OH)2D that was due to the enhanced expression of renal 25-hydroxyvitamin D-1alpha-hydroxylase (1alpha-OHase) from 10 days of age. These phenotypes could not be explained by currently known regulators of mineral homeostasis, indicating that FGF23 is essential for normal phosphate and vitamin D metabolism.

Vibrational spectroscopic characterization of the phosphate mineral ludlamite (Fe,Mn,Mg)₃(PO₄)₂⋅4H₂O - a mineral found in lithium bearing pegmatites.

PubMed

Frost, Ray L; Xi, Yunfei; Scholz, Ricardo; Belotti, Fernanda M

2013-02-15

The objective of this work is to analyze ludlamite (Fe,Mn,Mg)(3)(PO(4))(2)⋅4H(2)O from Boa Vista mine, Galiléia, Brazil and to assess the molecular structure of the mineral. The phosphate mineral ludlamite has been characterized by EMP-WDS, Raman and infrared spectroscopic measurements. The mineral is shown to be a ferrous phosphate with some minor substitution of Mg and Mn. Raman bands at 917 and 950 cm(-1) are assigned to the symmetric stretching mode of HOPO(3)(2-) and PO(4)(3-) units. Raman bands at 548, 564, 599 and 634 cm(-1) are assigned to the ν(4)PO(4)(3-) bending modes. Raman bands at 2605, 2730, 2896 and 3190 cm(-1) and infrared bands at 2623, 2838, 3136 and 3185 cm(-1) are attributed to water stretching vibrations. By using a Libowitzky empirical function, hydrogen bond distances are calculated from the OH stretching wavenumbers. Strong hydrogen bonds in the structure of ludlamite are observed as determined by their hydrogen bond distances. The application of infrared and Raman spectroscopy to the study of ludlamite enables the molecular structure of the pegmatite mineral ludlamite to be assessed. Copyright © 2012 Elsevier B.V. All rights reserved.

Microbial Mineral Weathering for Nutrient Acquisition Releases Arsenic

NASA Astrophysics Data System (ADS)

Mailloux, B. J.; Alexandrova, E.; Keimowitz, A.; Wovkulich, K.; Freyer, G.; Stolz, J.; Kenna, T.; Pichler, T.; Polizzotto, M.; Dong, H.; Radloff, K. A.; van Geen, A.

2008-12-01

Tens of millions of people in Southeast Asia drink groundwater contaminated with naturally occurring arsenic. The process of arsenic release from the sediment to the groundwater remains poorly understood. Experiments were performed to determine if microbial mineral weathering for nutrient acquisition can serve as a potential mechanism for arsenic mobilization. We performed microcosm experiments with Burkholderia fungorum, phosphate free artificial groundwater, and natural apatite. Controls included incubations with no cells and with killed cells. Additionally, samples were treated with two spikes - an arsenic spike, to show that arsenic release is independent of the initial arsenic concentration, and a phosphate spike to determine whether release occurs at field relevant phosphate conditions. We show in laboratory experiments that phosphate-limited cells of Burkholderia fungorum mobilize ancillary arsenic from apatite as a by-product of mineral weathering for nutrient acquisition. The released arsenic does not undergo a redox transformation but appears to be solubilized from the apatite mineral lattice as arsenate during weathering. Apatite has been shown to be commonly present in sediment samples from Bangladesh aquifers. Analysis of apatite purified from the Ganges, Brahamputra, Meghna drainage basin shows 210 mg/kg of arsenic, which is higher than the average crustal level. Finally, we demonstrate the presence of the microbial phenotype that releases arsenic from apatite in Bangladesh sediments. These results suggest that microbial weathering for nutrient acquisition could be an important mechanism for arsenic mobilization.

Geochemistry of phosphatic-shales and associated authigenic minerals of the Miocene Monterey Formation: Implications for paragenetic evolution

NASA Astrophysics Data System (ADS)

Sandoval, A.; Loyd, S. J.

2016-12-01

The Monterey Formation is a petroleum source and reservoir rock in California that was deposited in several basins during the tectonically-active Middle Miocene. The middle carbonaceous marl member of the Monterey Formation contains intervals of phosphatic-shales that are rhythmically cemented by dolomite as layers and concretions. Diagenetic minerals can form as the result of organic matter remineralization facilitated by microbes utilizing oxygen, nitrate, iron (III), sulfate and fermentation products as electron acceptors. Precipitation of phosphate and carbonate minerals tends to occur in suboxic-anoxic sediments, generally experiencing sulfate reduction, where degradation of organic matter yields alkalinity, sulfide and phosphate ions. Here, we present sulfur and carbon geochemical data in order to better characterize the conditions that led to the precipitation of phosphorous-rich minerals (e.g., carbonate-fluorapatite (CFA)) and dolomite that occur in close stratigraphic proximity. These data include concentration of CFA-associated sulfate, carbonate associated sulfate (CAS) and the respective δ°S values. The concentration of inorganic/organic carbon and associated δC values have been determined for CFA, dolomite and the host-shale, in order to further characterize the diagenetic environment of precipitation. These data indicate that authigenesis occurred in pore waters influenced by multiple microbial reactions, including respiration and methanogenesis reactions, and ultimately highlight the complexity of the Monterey diagenetic environment.

Biomineralization of U(VI) phosphate promoted by microbially-mediated phytate hydrolysis in contaminated soils

NASA Astrophysics Data System (ADS)

Salome, Kathleen R.; Beazley, Melanie J.; Webb, Samuel M.; Sobecky, Patricia A.; Taillefert, Martial

2017-01-01

The bioreduction of uranium may immobilize a significant fraction of this toxic contaminant in reduced environments at circumneutral pH. In oxic and low pH environments, however, the low solubility of U(VI)-phosphate minerals also makes them good candidates for the immobilization of U(VI) in the solid phase. As inorganic phosphate is generally scarce in soils, the biomineralization of U(VI)-phosphate minerals via microbially-mediated organophosphate hydrolysis may represent the main immobilization process of uranium in these environments. In this study, contaminated sediments were incubated aerobically in two pH conditions to examine whether phytate, a naturally-occurring and abundant organophosphate in soils, could represent a potential phosphorous source to promote U(VI)-phosphate biomineralization by natural microbial communities. While phytate hydrolysis was not evident at pH 7.0, nearly complete hydrolysis was observed both with and without electron donor at pH 5.5, suggesting indigenous microorganisms express acidic phytases in these sediments. While the rate of hydrolysis of phytate generally increased in the presence of uranium, the net rate of inorganic phosphate production in solution was decreased and inositol phosphate intermediates were generated in contrast to similar incubations conducted without uranium. These findings suggest uranium stress enhanced the phytate-metabolism of the microbial community, while simultaneously inhibiting phosphatase production and/or activity by the indigenous population. Finally, phytate hydrolysis drastically decreased uranium solubility, likely due to formation of ternary sorption complexes, U(VI)-phytate precipitates, and U(VI)-phosphate minerals. Overall, the results of this study provide evidence for the ability of natural microbial communities to liberate phosphate from phytate in acidic sediments, possibly as a detoxification mechanism, and demonstrate the potential utility of phytate-promoted uranium immobilization in subsurface environments. These processes should be investigated in more detail with pure cultures isolated from these sediments.

The effect of supplemental oral phosphate on the bone mineral changes during prolonged bed rest

PubMed Central

Hulley, Stephen B.; Vogel, John M.; Donaldson, Charles L.; Bayers, Jon H.; Friedman, Ronald J.; Rosen, Sheldon N.

1971-01-01

Five healthy young men were studied during 24-30 wk of continuous bed rest. During the first 12 wk of bed rest, untreated subjects increased calcium excretion in the urine by 109 mg/day and in the feces by 147 mg/day. The rate of total body calcium loss was 0.5-0.7% per month. Losses of central calcaneus mineral, assessed by gamma ray transmission scanning, occurred at a tenfold higher rate, whereas the mineral content of the radius did not change. Changes in phosphorus balance resembled the calcium pattern, and increased excretion of nitrogen and hydroxyproline also occurred during bed rest. Upon reambulation, the subjects' calcium balance became positive in 1 month and recovery of their calcaneus mineral was complete within 10-20 wk. Treatment with potassium phosphate supplements (1327 mg P/day) entirely prevented the hypercalciuria of bed rest, but fecal calcium tended to increase. During the first 12 wk, calcium balance was slightly less negative (mean - 193 mg/day) than during bed rest without added phosphate (mean - 267 mg/day). This effect was not seen during the second 12 wk of bed rest. The patterns of magnesium excretion were similar to those of calcium. Fecal and urinary phosphorus excretions were doubled, and phosphorus balance became positive (+ 113 mg/day). Mineral loss from the central calcaneus was similar to that of untreated subjects. It is concluded that this form of phosphate supplementation reduces urinary calcium excretion but does not prevent bone loss during bed rest. PMID:5129304

Effects of pH on the production of phosphate and pyrophosphate by matrix vesicles' biomimetics.

PubMed

Simão, Ana Maria S; Bolean, Maytê; Hoylaerts, Marc F; Millán, José Luis; Ciancaglini, Pietro

2013-09-01

During endochondral bone formation, chondrocytes and osteoblasts synthesize and mineralize the extracellular matrix through a process that initiates within matrix vesicles (MVs) and ends with bone mineral propagation onto the collagenous scaffold. pH gradients have been identified in the growth plate of long bones, but how pH changes affect the initiation of skeletal mineralization is not known. Tissue-nonspecific alkaline phosphatase (TNAP) degrades extracellular inorganic pyrophosphate (PPi), a mineralization inhibitor produced by ectonucleotide pyrophosphatase/phosphodiesterase-1 (NPP1), while contributing Pi from ATP to initiate mineralization. TNAP and NPP1, alone or combined, were reconstituted in dipalmitoylphosphatidylcholine liposomes to mimic the microenvironment of MVs. The hydrolysis of ATP, ADP, AMP, and PPi was studied at pH 8 and 9 and compared to the data determined at pH 7.4. While catalytic efficiencies in general were higher at alkaline pH, PPi hydrolysis was maximal at pH 8 and indicated a preferential utilization of PPi over ATP at pH 8 versus 9. In addition, all proteoliposomes induced mineral formation when incubated in a synthetic cartilage lymph containing 1 mM ATP as substrate and amorphous calcium phosphate or calcium-phosphate-phosphatidylserine complexes as nucleators. Propagation of mineralization was significantly more efficient at pH 7.5 and 8 than at pH 9. Since a slight pH elevation from 7.4 to 8 promotes considerably more hydrolysis of ATP, ADP, and AMP primarily by TNAP, this small pH change facilitates mineralization, especially via upregulated PPi hydrolysis by both NPP1 and TNAP, further elevating the Pi/PPi ratio, thus enhancing bone mineralization.

Defective Mineralization in X-Linked Hypophosphatemia Dental Pulp Cell Cultures.

PubMed

Coyac, B R; Hoac, B; Chafey, P; Falgayrac, G; Slimani, L; Rowe, P S; Penel, G; Linglart, A; McKee, M D; Chaussain, C; Bardet, C

2018-02-01

X-linked hypophosphatemia (XLH) is a skeletal disease caused by inactivating mutations in the PHEX gene. Mutated or absent PHEX protein/enzyme leads to a decreased serum phosphate level, which cause mineralization defects in the skeleton and teeth (osteomalacia/odontomalacia). It is not yet altogether clear whether these manifestations are caused solely by insufficient circulating phosphate availability for mineralization or also by a direct, local intrinsic effect caused by impaired PHEX activity. Here, we evaluated the local role of PHEX in a 3-dimensional model of extracellular matrix (ECM) mineralization. Dense collagen hydrogels were seeded either with human dental pulp cells from patients with characterized PHEX mutations or with sex- and age-matched healthy controls and cultured up to 24 d using osteogenic medium with standard phosphate concentration. Calcium quantification, micro-computed tomography, and histology with von Kossa staining for mineral showed significantly lower mineralization in XLH cell-seeded scaffolds, using nonparametric statistical tests. While apatitic mineralization was observed along collagen fibrils by electron microscopy in both groups, Raman microspectrometry indicated that XLH cells harboring the PHEX mutation produced less mineralized scaffolds having impaired mineral quality with less carbonate substitution and lower crystallinity. In the XLH cultures, immunoblotting revealed more abundant osteopontin (OPN), dentin matrix protein 1 (DMP1), and matrix extracellular phosphoglycoprotein (MEPE) than controls, as well as the presence of fragments of these proteins not found in controls, suggesting a role for PHEX in SIBLING protein degradation. Immunohistochemistry revealed altered OPN and DMP1 associated with an increased alkaline phosphatase staining in the XLH cultures. These results are consistent with impaired PHEX activity having local ECM effects in XLH. Future treatments for XLH should target both systemic and local manifestations.

Approaches to modelling uranium (VI) adsorption on natural mineral assemblages

USGS Publications Warehouse

Waite, T.D.; Davis, J.A.; Fenton, B.R.; Payne, T.E.

2000-01-01

Component additivity (CA) and generalised composite (GC) approaches to deriving a suitable surface complexation model for description of U(VI) adsorption to natural mineral assemblages are pursued in this paper with good success. A single, ferrihydrite-like component is found to reasonably describe uranyl uptake to a number of kaolinitic iron-rich natural substrates at pH > 4 in the CA approach with previously published information on nature of surface complexes, acid-base properties of surface sites and electrostatic effects used in the model. The GC approach, in which little pre-knowledge about generic surface sites is assumed, gives even better fits and would appear to be a method of particular strength for application in areas such as performance assessment provided the model is developed in a careful, stepwise manner with simplicity and goodness of fit as the major criteria for acceptance.

Investigation of uranium binding forms in selected German mineral waters.

PubMed

Osman, Alfatih A A; Geipel, Gerhard; Bernhard, Gert; Worch, Eckhard

2013-12-01

Cryogenic time-resolved laser-induced fluorescence spectroscopy was successfully used to identify uranium binding forms in selected German mineral waters of extremely low uranium concentrations (<2.0 μg/L). The measurements were performed at a low temperature of 153 K. The spectroscopic data showed a prevalence of aquatic species Ca2UO2(CO3)3 in all investigated waters, while other uranyl-carbonate complexes, viz, UO2CO3(aq) and UO2(CO3)2 (2-), only existed as minor species. The pH value, alkalinity (CO3 (2-)), and the main water inorganic constituents, specifically the Ca(2+) concentration, showed a clear influence on uranium speciation. Speciation modeling was performed using the most recent thermodynamic data for aqueous complexes of uranium. The modeling results for the main uranium binding form in the investigated waters indicated a good agreement with the spectroscopy measurements.

Partitioning of uranyl between ferrihydrite and humic substances at acidic and circum-neutral pH

DOE PAGES

Dublet, Gabrielle; Lezama Pacheco, Juan; Bargar, John R.; ...

2017-07-14

As part of a larger study of the reactivity and mobility of uranyl (U(VI)O 2 2+) cations in subsurface environments containing natural organic matter (NOM) and hydrous ferric oxides, we have examined the effect of reference humic and fulvic substances on the sorption of uranyl on 2-line ferrihydrite (Fh), a common, naturally occurring nano-Fe(III)-hydroxide. Uranyl was reacted with Fh at pH 4.6 and 7.0 in the presence and absence of Elliott Soil Humic Acid (ESHA) (0–835 ppm) or Suwanee River Fulvic Acid (SRFA) (0–955 ppm). Here, no evidence was found for reduction of uranyl by either form of NOM aftermore » 24 h of exposure.« less

Partitioning of uranyl between ferrihydrite and humic substances at acidic and circum-neutral pH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dublet, Gabrielle; Lezama Pacheco, Juan; Bargar, John R.

As part of a larger study of the reactivity and mobility of uranyl (U(VI)O 2 2+) cations in subsurface environments containing natural organic matter (NOM) and hydrous ferric oxides, we have examined the effect of reference humic and fulvic substances on the sorption of uranyl on 2-line ferrihydrite (Fh), a common, naturally occurring nano-Fe(III)-hydroxide. Uranyl was reacted with Fh at pH 4.6 and 7.0 in the presence and absence of Elliott Soil Humic Acid (ESHA) (0–835 ppm) or Suwanee River Fulvic Acid (SRFA) (0–955 ppm). Here, no evidence was found for reduction of uranyl by either form of NOM aftermore » 24 h of exposure.« less

Uranyl interaction with the hydrated (001) basal face of gibbsite: a combined theoretical and spectroscopic study.

PubMed

Veilly, Edouard; Roques, Jérôme; Jodin-Caumon, Marie-Camille; Humbert, Bernard; Drot, Romuald; Simoni, Eric

2008-12-28

The sorption of uranyl cations and water molecules on the basal (001) face of gibbsite was studied by combining vibrational and fluorescence spectroscopies together with density functional theory (DFT) computations. Both the calculated and experimental values of O-H bond lengths for the gibbsite bulk are in good agreement. In the second part, water sorption with this surface was studied to take into account the influence of hydration with respect to the uranyl adsorption. The computed water configurations agreed with previously published molecular dynamics studies. The uranyl adsorption in acidic media was followed by time-resolved laser-induced fluorescence spectroscopy and Raman spectrometry measurements. The existence of only one kind of adsorption site for the uranyl cation was then indicated in good agreement with the DFT calculations. The computation of the uranyl adsorption has been performed by means of a bidentate interaction with two surface oxygen atoms. The optimized structures displayed strong hydrogen bonds between the surface and the -yl oxygen of uranyl. The uranium-surface bond strength depends on the protonation state of the surface oxygen atoms. The calculated U-O(surface) bond lengths range between 2.1-2.2 and 2.6-2.7 A for the nonprotonated and protonated surface O atoms, respectively.

Phosphatic precipitates associated with actinomycetes in speleothems from Grand Cayman, British West Indies

NASA Astrophysics Data System (ADS)

Jones, Brian

2009-07-01

Calcitic speleothems from a cave located on the north central coast of Grand Cayman commonly include corrosion surfaces that developed when calcite precipitation ceased and corrosion mediated by condensates became the operative process. Dissolution features associated with these surfaces, including etched crystal surfaces, microcavities, and solution-widened boundaries between crystals, are commonly occupied by microbes and microbial mats that have been replaced by calcium phosphate and/or coated with calcium phosphate. No mineralized microbes were found in the calcite crystals that form the speleothems. The morphology of the mineralized hyphae (eight morphotypes) and spores (nine morphotypes) are indicative of actinomycetes, a group of microbes that are ideally adapted to life in oligotrophic cave environs. Superb preservation of the delicate hyphae, aerial hyphae, and delicate ornamentation on the hyphae and spores indicate that the microbes underwent rapid mineralized while close to their original life positions. Although these actinomycetes were extremely susceptible to replacement by calcium phosphate, there is no evidence that they directly or indirectly controlled precipitation. Nevertheless, the association between the P-rich precipitates and microbes shows that the use of phosphorus as a proxy for seasonal climate changes in paleoclimate analyses must be treated with caution.

Microbial processes dominate P fluxes in a low-phosphorus temperate forest soil: insights provided by 33P and 18O in phosphate

NASA Astrophysics Data System (ADS)

Pistocchi, Chiara; Tamburini, Federica; Bünemann, Else; Mészáros, Éva; Frossard, Emmanuel

2016-04-01

The classical view of the P cycle in forests is that trees and mycorrhizal fungi associated with them take up most of their phosphorus as phosphate (P) from the soil solution. The soil solution is then replenished by the release of P from sorbed phases, by the dissolution of P containing minerals or by biological mineralization and/or enzymatic hydrolysis of organic P compounds. Direct insight into the processes phosphate goes through at the ecosystem level is, however, missing. Assessing the relevance of inorganic and biological processes controlling P cycling requires the use of appropriate approaches and tracers. Within the German Priority Program "Ecosystem Nutrition: Forest Strategies for limited Phosphorus Resources" we studied P forms and dynamics in organic horizons (Of/Oh) of temperate beech forest soils in Germany with contrasting soil P availability (P-poor and P-rich). We followed the fate of P from the litter into the soil pools, using isotopes as tracers (stable oxygen isotopes in water and phosphate and 33P) and relied on measurements in experimental forest sites and a three-months incubation experiment with litter addition. Using an isotopic dilution approach we were able to estimate gross (7 mg P kg-1 d-1 over the first month) and net mineralization rates (about 5 mg P kg-1 d-1 over the first 10 days) in the P-poor soil. In this soil the immobilization of P in the microbial biomass ranged from 20 to 40% of gross mineralization during the incubation, meaning that a considerable part of mineralized P contributed to replenish the available P pool. In the P-rich soil, physicochemical processes dominated exchangeable P to the point that the contribution of biological/biochemical processes was non-detectable. Oxygen isotopes in phosphate elucidated that organic P mineralization by enzymatic hydrolysis gains more importance with decreasing P availability, both under controlled and under field conditions. In summary, microbial processes dominated P fluxes (70 to 80%) in the P-poor soil, while in the P-rich soil microbial processes could not be detected because of the higher baseline of physicochemical processes. Our results support the hypothesis that organic P has a faster turnover under conditions of low P availability and that net mineralization is the most relevant process providing available P for plants under these conditions.

Biotic and abiotic pathways of phosphorus cycling in minerals and sediments: insights from oxygen isotopes in phosphate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaisi, Deb P.; Kukkadapu, Ravi K.; Stout, Lisa M.

2011-07-06

A key question to address in the development of oxygen isotope ratios in phosphate (18Op) as a tracer of biogeochemical cycling of phosphorus in ancient and modern environments is the nature of isotopic signatures associated with uptake and cycling of mineral-bound phosphate by microorganisms. Here we present experimental results aimed at understanding the biotic and abiotic pathway of P cycling during biological uptake of phosphate sorbed to ferrihydrite and the selective uptake of specific sedimentary phosphate phases by Escherichia coli, Vibrio fischeri and Marinobacter aquaeolei. Results indicate that a significant fraction of ferrihydrite-bound phosphate is biologically available. The fraction ofmore » phosphate taken up by E. coli attained an equilibrium isotopic composition in a short time (<50 hrs) due to efficient O-isotope exchange between phosphate and water (biotic pathway). The difference in isotopic composition between newly equilibrated aqueous and residual sorbed phosphate promoted the exchange of intact phosphate radicals (abiotic pathway) so that this difference gradually became negligible. In sediment containing different P phases, E. coli and V. fischeri ‘extracted’ loosely sorbed phosphate first while M. aquaeolei preferred iron-oxide bound phosphate. Each bacterium imprinted a biotic isotopic signature on each P phase that it took up and cycled. For example, the 18Op value of the sorbed phosphate phase shifted gradually towards equilibrium isotopic composition and the value of Fe oxide-bound phosphate showed slight changes at first, but when new iron oxides were formed, co-precipitated/occluded phosphate retained 18O values of aqueous phosphate at that time. Concentrations and isotopic compositions of authigenic and detrital phosphates did not change, suggesting that these phosphate phases were not utilized by bacteria. These findings support burgeoning applications of 18Op as a tracer of phosphorus cycling in sediments, soils and aquatic environments and as an indicator of paleo- environmental conditions.« less

Hypophosphatemic rickets with hypocalciuria following long-term treatment with aluminum-containing antacid.

PubMed

Foldes, J; Balena, R; Ho, A; Parfitt, A M; Kleerekoper, M

1991-01-01

We present what we believe is the first case of rickets following prolonged treatment with aluminum containing antacids that bind phosphate, in an 18-year-old mentally retarded boy with cerebral palsy and spastic quadriplegia. As expected, serum calcitriol was increased and urinary phosphate excretion was very low. However, in contrast to all published cases of antacid induced hypophosphatemic osteomalacia in adults, despite a substantial increase in bone resorption reflected by urinary total hydroxyproline excretion, urinary calcium excretion was low rather than high, and significant hypocalcemia occurred after antacids were ceased and a phosphate salt administered. We suggest that the skeleton was so under-mineralized because of growth during prolonged phosphate deficiency, possibly augmented by anticonvulsant administration and immobilization, that increased bone resorption did not release enough calcium to cause hypercalciuria, or to prevent hypocalcemia during resumption of normal mineralization.

A surface structural model for ferrihydrite I: Sites related to primary charge, molar mass, and mass density

NASA Astrophysics Data System (ADS)

Hiemstra, Tjisse; Van Riemsdijk, Willem H.

2009-08-01

A multisite surface complexation (MUSIC) model for ferrihydrite (Fh) has been developed. The surface structure and composition of Fh nanoparticles are described in relation to ion binding and surface charge development. The site densities of the various reactive surface groups, the molar mass, the mass density, the specific surface area, and the particle size are quantified. As derived theoretically, molecular mass and mass density of nanoparticles will depend on the types of surface groups and the corresponding site densities and will vary with particle size and surface area because of a relatively large contribution of the surface groups in comparison to the mineral core of nanoparticles. The nano-sized (˜2.6 nm) particles of freshly prepared 2-line Fh as a whole have an increased molar mass of M ˜ 101 ± 2 g/mol Fe, a reduced mass density of ˜3.5 ± 0.1 g/cm 3, both relatively to the mineral core. The specific surface area is ˜650 m 2/g. Six-line Fh (5-6 nm) has a molar mass of M ˜ 94 ± 2 g/mol, a mass density of ˜3.9 ± 0.1 g/cm 3, and a surface area of ˜280 ± 30 m 2/g. Data analysis shows that the mineral core of Fh has an average chemical composition very close to FeOOH with M ˜ 89 g/mol. The mineral core has a mass density around ˜4.15 ± 0.1 g/cm 3, which is between that of feroxyhyte, goethite, and lepidocrocite. These results can be used to constrain structural models for Fh. Singly-coordinated surface groups dominate the surface of ferrihydrite (˜6.0 ± 0.5 nm -2). These groups can be present in two structural configurations. In pairs, the groups either form the edge of a single Fe-octahedron (˜2.5 nm -2) or are present at a single corner (˜3.5 nm -2) of two adjacent Fe octahedra. These configurations can form bidentate surface complexes by edge- and double-corner sharing, respectively, and may therefore respond differently to the binding of ions such as uranyl, carbonate, arsenite, phosphate, and others. The relatively low PZC of ferrihydrite can be rationalized based on the estimated proton affinity constant for singly-coordinated surface groups. Nanoparticles have an enhanced surface charge. The charging behavior of Fh nanoparticles can be described satisfactory using the capacitance of a spherical Stern layer condenser in combination with a diffuse double layer for flat plates.

Preparation of U.sub.3 O.sub.8

DOEpatents

Johnson, David R.

1980-01-01

A method is described for the preparation of U.sub.3 O.sub.8 nuclear fuel material by direct precipitation of uranyl formate monohydrate from uranyl nitrate solution. The uranyl formate monohydrate precipitate is removed, dried and calcined to produce U.sub.3 O.sub.8 having a controlled particle size distribution.

Structure and Reactivity of X-ray Amorphous Uranyl Peroxide, U 2O 7

DOE PAGES

Odoh, Samuel O.; Shamblin, Jacob; Colla, Christopher A.; ...

2016-03-14

Recent accidents resulting in worker injury and radioactive contamination occurred due to pressurization of uranium yellowcake drums produced in the western USA. The drums contained an unexpected X-ray amorphous reactive form of uranium oxide, U 2O7. Heating hydrated uranyl peroxides produced during in situ mining unintentionally produced U 2O 7. It is a hygroscopic anhydrous uranyl peroxide that reacts rapidly with water to release O 2 gas and form metaschoepite, a uranyl-oxide hydrate. Quantum chemical calculations indicate that the most stable U 2O 7 conformer consists of two bent (UO 2) 2+ uranyl ions bridged by a peroxide group bidentatemore » and parallel to each uranyl ion, and a μ2-O atom, resulting in charge neutrality. A pair distribution function from neutron total scattering supports this structural model. The reactivity of U 2O 7 in water and with water in air is much higher than other uranium oxides, and this can be both hazardous and potentially advantageous in the nuclear fuel cycle.« less

Controlling the strontium-doping in calcium phosphate microcapsules through yeast-regulated biomimetic mineralization.

PubMed

Huang, Miaojun; Li, Tianjie; Pan, Ting; Zhao, Naru; Yao, Yongchang; Zhai, Zhichen; Zhou, Jiaan; Du, Chang; Wang, Yingjun

2016-10-01

Yeast cells have controllable biosorption on metallic ions during metabolism. However, few studies were dedicated to using yeast-regulated biomimetic mineralization process to control the strontium-doped positions in calcium phosphate microcapsules. In this study, the yeast cells were allowed to pre-adsorb strontium ions metabolically and then served as sacrificing template for the precipitation and calcination of mineral shell. The pre-adsorption enabled the microorganism to enrich of strontium ions into the inner part of the microcapsules, which ensured a slow-release profile of the trace element from the microcapsule. The co-culture with human marrow stromal cells showed that gene expressions of alkaline phosphatase and Collagen-I were promoted. The promotion of osteogenic differentiation was further confirmed in the 3D culture of cell-material complexes. The strategy using living microorganism as 'smart doping apparatus' to control incorporation of trace element into calcium phosphate paved a pathway to new functional materials for hard tissue regeneration.

The Itataia phosphate-uranium deposit (Ceará, Brazil) new petrographic, geochemistry and isotope studies

NASA Astrophysics Data System (ADS)

Veríssimo, César Ulisses Vieira; Santos, Roberto Ventura; Parente, Clóvis Vaz; Oliveira, Claudinei Gouveia de; Cavalcanti, José Adilson Dias; Nogueira Neto, José de Araújo

2016-10-01

The Itataia phosphate-uranium deposit is located in Santa Quitéria, in central Ceará State, northeastern Brazil. Mineralization has occurred in different stages and involves quartz leaching (episyenitization), brecciation and microcrystalline phase formation of concretionary apatite. The last constitutes the main mineral of Itatiaia uranium ore, namely collophane. Collophanite ore occurs in massive bodies, lenses, breccia zones, veins or episyenite in marble layers, calc-silicate rocks and gneisses of the Itataia Group. There are two accepted theories on the origin of the earliest mineralization phase of Itataia ore: syngenetic (primary) - where the ore is derived from a continental source and then deposited in marine and coastal environments; and epigenetic (secondary) - whereby the fluids are of magmatic, metamorphic and meteoric origin. The characterization of pre- or post-deformational mineralization is controversial, since the features of the ore are interpreted as deformation. This investigation conducted isotopic studies and chemical analyses of minerals in marbles and calc-silicate rocks of the Alcantil and Barrigas Formations (Itataia Group), as well as petrographic and structural studies. Analysis of the thin sections shows at least three phosphate mineral phases associated with uranium mineralizaton: (1) A prismatic fluorapatite phase associated with chess-board albite, arfvedsonite and ferro-eckermannite; (2) a second fluorapatite phase with fibrous radial or colloform habits that replaces calcium carbonate in marble, especially along fractures, with minerals such as quartz, chlorite and zeolite also identified in calc-silicate rocks; and (3) an younger phosphate phase of botryoidal apatite (fluorapatite and hydroxyapatite) related with clay minerals and probably others calcium and aluminum phosphates. Detailed isotopic analysis carried out perpendicularly to the mineralized levels and veins in the marble revealed significant variation in isotopic ratios. Mineralized zones exhibit a decrease in δ13C and δ18O isotope values and a higher 87Sr/86Sr ratio toward the center of the vein. In conjunction with petrographic studies, these changes contesting the hypothesis of a sedimentary origin for uranium and suggest a radiogenic Sr input by alkaline to peralkaline fluids from fertile granites of the end of Brasiliano/Pan-African orogeny, located outside the deposit. The origin of the phosphorous is associated with phosphorite deposits in the same depositional environment of the neoproterozoic supracrustal quartz-pelite-carbonate sediments of the Itataia Group. Considering the studies conducted here and available geological data, three main mineralizing events can be identified in Itataia: (1) an initial high temperature event connected with a sodium metasomatism-related uranium episode, taking place in Borborema Province and its African counterpart; (2) a second lower temperature stage, consisting of a multiphase cataclastic/hydrothermal event limited to fault and paleokarst zones; and (3) a third and final event, developed in frankly oxidizing conditions. The last two involving mixing of hydrothermal and meteoric fluids.

Uranyl sulfate irradiations at the Van de Graaff: A means to combat uranyl peroxide precipitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Youker, Amanda J.; Kalensky, Michael; Quigley, Kevin J.

As part of an effort to support SHINE Medical Technologies in developing a process to produce Mo-99 by neutron-induced fission, a series of irradiation experiments was performed with a 3 MeV Van de Graaff accelerator to generate high radiation doses in 0.5–2 mL uranyl sulfate solutions. The purpose was to determine what conditions result in uranyl peroxide precipitation and what can be done to prevent its formation. The effects of temperature, dose rate, uranium concentration, and the addition of known catalysts for the destruction of peroxide were determined.

JACK CREEK BASIN, MONTANA.

USGS Publications Warehouse

Kiilsgaard, Thor H.; Van Noy, Ronald M.

1984-01-01

A mineral survey of the Jack Creek basin area in Montana revealed that phosphate rock underlies the basin. The phosphate rock is in thin beds that dip steeply and are broken and offset by faults. These features plus the rugged topography of the region would make mining difficult; however, this study finds the area to have a probable mineral-resource potential for phosphate. Sedimentary rock formations favorable for oil and gas also underlie the basin. No oil or gas has been produced from the basin or from nearby areas in southwestern Montana, but oil and gas have been produced from the same favorable formations elsewhere in Montana. The possibility of oil and gas being produced from the basin is slight but it cannot be ignored.

BASIC PEROXIDE PRECIPITATION METHOD OF SEPARATING PLUTONIUM FROM CONTAMINANTS

DOEpatents

Seaborg, G.T.; Perlman, I.

1959-02-10

A process is described for the separation from each other of uranyl values, tetravalent plutonium values and fission products contained in an aqueous acidic solution. First the pH of the solution is adjusted to between 2.5 and 8 and hydrogen peroxide is then added to the solution causing precipitation of uranium peroxide which carries any plutonium values present, while the fission products remain in solution. Separation of the uranium and plutonium values is then effected by dissolving the peroxide precipitate in an acidic solution and incorporating a second carrier precipitate, selective for plutonium. The plutonium values are thus carried from the solution while the uranium remains flissolved. The second carrier precipitate may be selected from among the group consisting of rare earth fluorides, and oxalates, zirconium phosphate, and bismuth lihosphate.

Osteocyte regulation of phosphate homeostasis and bone mineralization underlies the pathophysiology of the heritable disorders of rickets and osteomalacia

PubMed Central

Feng, Jian Q.; Clinkenbeard, Erica L.; Yuan, Baozhi; White, Kenneth E.; Drezner, Marc K.

2013-01-01

Although recent studies have established that osteocytes function as secretory cells that regulate phosphate metabolism, the biomolecular mechanism(s) underlying these effects remain incompletely defined. However, investigations focusing on the pathogenesis of X-linked hypophosphatemia (XLH), autosomal dominant hypophosphatemic rickets (ADHR), and autosomal recessive hypophosphatemic rickets (ARHR), heritable disorders characterized by abnormal renal phosphate wasting and bone mineralization, have clearly implicated FGF23 as a central factor in osteocytes underlying renal phosphate wasting, documented new molecular pathways regulating FGF23 production, and revealed complementary abnormalities in osteocytes that regulate bone mineralization. The seminal observations leading to these discoveries were the following: 1) mutations in FGF23 cause ADHR by limiting cleavage of the bioactive intact molecule, at a subtilisin-like protein convertase (SPC) site, resulting in increased circulating FGF23 levels and hypophosphatemia; 2) mutations in DMP1 cause ARHR, not only by increasing serum FGF23, albeit by enhanced production and not limited cleavage, but also by limiting production of the active DMP1 component, the C-terminal fragment, resulting in dysregulated production of DKK1 and β-catenin, which contributes to impaired bone mineralization; and 3) mutations in PHEX cause XLH both by altering FGF23 proteolysis and production and causing dysregulated production of DKK1 and β-catenin, similar to abnormalities in ADHR and ARHR, but secondary to different central pathophysiological events. These discoveries indicate that ADHR, XLH, and ARHR represent three related heritable hypophosphatemic diseases that arise from mutations in, or dysregulation of, a single common gene product, FGF23 and, in ARHR and XLH, complimentary DMP1 and PHEX directed events that contribute to abnormal bone mineralization. PMID:23403405

Complementary information on in vitro conversion of amorphous (precursor) calcium phosphate to hydroxyapatite from Raman microspectroscopy and wide-angle X-ray scattering.

PubMed

Kazanci, M; Fratzl, P; Klaushofer, K; Paschalis, E P

2006-11-01

In addition to mechanical functions, bones have an essential role in metabolic activity as mineral reservoirs that are able to absorb and release ions. Bioapatite, considered the major component in the mineralized part of mammalian bones, is a calcium phosphate mineral with a structure that closely resembles hydroxyapatite (HA, Ca10[PO4]6[OH]2) with variable chemical substitutions. It is important to note that it continues to be chemically active long after it has been initially deposited. Detailed understanding of changes in the mineral phase as HA matures is essential for understanding how normal bone achieves its remarkable mechanical performance, how it is altered in disease, as well as the effects of therapeutic interventions. A model system for investigation of the in vivo maturation of HA is available, namely, the in vitro conversion of amorphous calcium phosphate (ACP) to HA in a supersaturated solution of calcium and phosphate ions. In the present study, this system was employed to correlate with the changes in chemistry and poorly crystalline HAP crystal size, shape, and habit. The results of the X-ray diffraction as well as Raman analyses showed that as the crystallites mature in the 002 and 310 directions both the full width at half-height and wavelength at maximum of the Raman peaks change as a function of reaction extent and crystallite maturation, size, and shape. Moreover, such analyses can be performed in intact bone specimens through Raman microspectroscopic and imaging analyses with a spatial resolution of 0.6-1 mu, by far superior to the one offered by other microspectroscopic techniques, thus potentially yielding important new information on the organization and mineral quality of normal and fragile bone.

Theoretical insights into the uranyl adsorption behavior on vanadium carbide MXene

NASA Astrophysics Data System (ADS)

Zhang, Yu-Juan; Zhou, Zhang-Jian; Lan, Jian-Hui; Ge, Chang-Chun; Chai, Zhi-Fang; Zhang, Peihong; Shi, Wei-Qun

2017-12-01

Remediation of the contamination by long-lived actinide wastes is extremely important but also challenging. Adsorption based techniques have attracted much research attention for their potential as low-cost and effective methods to reduce the radioactive waste from solution. In this work, we have investigated the adsorption behavior of uranyl species [with the general form UO2(L1)x(L2)y(L3)z, where L1, L2 and L3 stand for ligands H2O, OH and CO3, respectively] on hydroxylated vanadium carbide V2C(OH)2 MXene nanosheets using density functional theory based simulation methods We find that all studied uranyl species can stably bond to hydroxylated MXene with binding energies ranging from -3.3 to -4.6 eV, suggesting that MXenes could be effective adsorbers for uranyl ions. The strong adsorption is achieved by forming two Usbnd O bonds with the hydroxylated Mxene. In addition, the axial oxygen atoms from the uranyl ions form hydrogen bonds with the hydroxylated V2C, further strengthening the adsorption. We have also investigated the effects of F termination on the uranyl adsorption properties of V2C nanosheets. Usbnd F bonds are in general weaker than Usbnd O bonds on the adsorption site, suggesting that F terminated Mexne is less favorable for uranyl adsorption applications.

Self-assembly of silver nanoparticles as high active surface-enhanced Raman scattering substrate for rapid and trace analysis of uranyl(VI) ions

NASA Astrophysics Data System (ADS)

Wang, Shaofei; Jiang, Jiaolai; Wu, Haoxi; Jia, Jianping; Shao, Lang; Tang, Hao; Ren, Yiming; Chu, Mingfu; Wang, Xiaolin

2017-06-01

A facile surface-enhanced Raman scattering (SERS) substrate based on the self-assembly of silver nanoparticles on the modified silicon wafer was obtained, and for the first time, an advanced SERS analysis method basing on this as-prepared substrate was established for high sensitive and rapid detection of uranyl ions. Due to the weakened bond strength of Odbnd Udbnd O resulting from two kinds of adsorption of uranyl species (;strong; and ;weak; adsorption) on the substrate, the ν1 symmetric stretch vibration frequency of Odbnd Udbnd O shifted from 871 cm- 1 (normal Raman) to 720 cm- 1 and 826 cm- 1 (SERS) along with significant Raman enhancement. Effects of the hydrolysis of uranyl ions on SERS were also investigated, and the SERS band at 826 cm- 1 was first used to approximately define the constitution of uranyl species at trace quantity level. Besides, the SERS intensity was proportional to the variable concentrations of uranyl nitrate ranging from 10- 7 to 10- 3 mol L- 1 with an excellent linear relation (R2 = 0.998), and the detection limit was 10- 7 mol L- 1. Furthermore, the related SERS approach involves low-cost substrate fabrication, rapid and trace analysis simultaneously, and shows great potential applications for the field assays of uranyl ions in the nuclear fuel cycle and environmental monitoring.

PO43 Removal by and Permeability of Industrial Byproducts and Minerals: Granulated Blast Furnace Slag, Cement Kiln Dust, Coconut Shell Activated Carbon, Silica Sand and Zeolite

USDA-ARS?s Scientific Manuscript database

Excess aqueous concentration of phosphate degrades the overall water quality of the receiving surface waters in a cumulatively damaging process referred to as eutrophication. Adsorption of excess phosphate has proven to be the most effective, and economical methods of phosphate removal from such wat...

Just-in-time vaccines: Biomineralized calcium phosphate core-immunogen shell nanoparticles induce long-lasting CD8(+) T cell responses in mice.

PubMed

Zhou, Weibin; Moguche, Albanus O; Chiu, David; Murali-Krishna, Kaja; Baneyx, François

2014-04-01

Distributed and on-demand vaccine production could be game-changing for infectious disease treatment in the developing world by providing new therapeutic opportunities and breaking the refrigeration "cold chain". Here, we show that a fusion protein between a calcium phosphate binding domain and the model antigen ovalbumin can mineralize a biocompatible adjuvant in a single step. The resulting 50 nm calcium phosphate core-immunogen shell particles are comparable to soluble protein in inducing ovalbumin-specific antibody response and class switch recombination in mice. However, single dose vaccination with nanoparticles leads to higher expansion of ovalbumin-specific CD8(+) T cells upon challenge with an influenza virus bearing the ovalbumin-derived SIINFEKL peptide, and these cells produce high levels of IFN-γ. Furthermore, mice exhibit a robust antigen-specific CD8(+) T cell recall response when challenged with virus 8 months post-immunization. These results underscore the promise of immunogen-controlled adjuvant mineralization for just-in-time manufacturing of effective T cell vaccines. This paper reports that a fusion protein between a calcium phosphate binding domain and the model antigen ovalbumin can mineralize into a biocompatible adjuvant in a single step, enabling distributed and on-demand vaccine production and eliminating the need for refrigeration of vaccines. The findings highlight the possibility of immunogen-controlled adjuvant mineralization for just-in-time manufacturing of effective T cell vaccines. Copyright © 2014 Elsevier Inc. All rights reserved.

Equatorial coordination of uranyl: Correlating ligand charge donation with the O yl-U-O yl asymmetric stretch frequency

DOE PAGES

Gibson, John K.; de Jong, Wibe A.; van Stipdonk, Michael J.; ...

2017-10-14

In uranyl coordination complexes, UO 2(L) n 2+, uranium in the formally dipositive [O=U=O] 2+ moiety is coordinated by n neutral organic electron donor ligands, L. The extent of ligand electron donation, which results in partial reduction of uranyl and weakening of the U=O bonds, is revealed by the magnitude of the red-shift of the uranyl asymmetric stretch frequency, ν 3 . This phenomenon appears in gas-phase complexes in which uranyl is coordinated by electron donor ligands: the ν 3 red-shift increases as the number of ligands and their proton affinity (PA) increases. Because PA is a measure of themore » enthalpy change associated with a proton-ligand interaction, which is much stronger and of a different nature than metal ion-ligand bonding, it is not necessarily expected that ligand PAs should reliably predict uranyl-ligand bonding and the resulting ν 3 red-shift. In this study, ν 3 was measured for uranyl coordinated by ligands with a relatively broad range of PAs, revealing a surprisingly good correlation between PA and ν 3 frequency. From computed ν 3 frequencies for bare UO 2 cations and neutrals, it is inferred that the effective charge of uranyl in UO 2(L) n 2+ complexes can be reduced to near zero upon ligation by sufficiently strong charge-donor ligands. The basis for the correlation between ν 3 and ligand PAs, as well as limitations and deviations from it, are considered. It is demonstrated that the correlation evidently extends to a ligand that exhibits polydentate metal ion coordination.« less

Surface complexation model of uranyl sorption on Georgia kaolinite

USGS Publications Warehouse

Payne, T.E.; Davis, J.A.; Lumpkin, G.R.; Chisari, R.; Waite, T.D.

2004-01-01

The adsorption of uranyl on standard Georgia kaolinites (KGa-1 and KGa-1B) was studied as a function of pH (3-10), total U (1 and 10 ??mol/l), and mass loading of clay (4 and 40 g/l). The uptake of uranyl in air-equilibrated systems increased with pH and reached a maximum in the near-neutral pH range. At higher pH values, the sorption decreased due to the presence of aqueous uranyl carbonate complexes. One kaolinite sample was examined after the uranyl uptake experiments by transmission electron microscopy (TEM), using energy dispersive X-ray spectroscopy (EDS) to determine the U content. It was found that uranium was preferentially adsorbed by Ti-rich impurity phases (predominantly anatase), which are present in the kaolinite samples. Uranyl sorption on the Georgia kaolinites was simulated with U sorption reactions on both titanol and aluminol sites, using a simple non-electrostatic surface complexation model (SCM). The relative amounts of U-binding >TiOH and >AlOH sites were estimated from the TEM/EDS results. A ternary uranyl carbonate complex on the titanol site improved the fit to the experimental data in the higher pH range. The final model contained only three optimised log K values, and was able to simulate adsorption data across a wide range of experimental conditions. The >TiOH (anatase) sites appear to play an important role in retaining U at low uranyl concentrations. As kaolinite often contains trace TiO2, its presence may need to be taken into account when modelling the results of sorption experiments with radionuclides or trace metals on kaolinite. ?? 2004 Elsevier B.V. All rights reserved.

Geochemical and textural characterization of phosphate accessory phases in the vein assemblage and metasomatically altered Llallagua tin porphyry

NASA Astrophysics Data System (ADS)

Betkowski, Wladyslaw B.; Rakovan, John; Harlov, Daniel E.

2017-09-01

Petrographic and geochemical characterization of phosphate accessory minerals represents a powerful tool in understanding the mineralization and metasomatic history of one of the world's biggest tin deposits, the Siglo XX mine, Salvadora stock, Llallagua, Bolivia. The Llallagua tin deposit lies in a hydrothermally altered porphyry stock that is part of the subduction-related Bolivian tin belt. Despite numerous studies, there is still a debate over the timing and characteristics of mineralization history of the deposit. Primary igneous fluorapatite and monazite (for the first time) were recognized in the altered porphyry. The igneous monazite is enriched in Th, unlike the hydrothermal monazite that is recognized for its low Th concentration. Fluorapatite, monazite, and xenotime also coexist with cassiterite within the hydrothermal vein assemblage. Fluorapatite and xenotime are essentially pristine. Monazite, however, shows various degrees of alteration in the form of regenerative mineral replacement (RMR). This exemplifies differential reactivity and selective mineral replacement/alteration of three accessory phosphate minerals, that are all important geochemical tracers of magmatic and hydrothermal processes, and which can all be used as geochronometers. Mineral textures and composition in the altered porphyry and vein assemblages have been evaluated. Monazite-xenotime geothermometry indicates monazite crystallization beginning around 550 °C. Monazite continues to grow as temperatures gradually decrease to about 300 °C, when most of cassiterite precipitation occurred in the samples studied. The primary mechanism of phosphate alteration has been identified as a coupled dissolution-reprecipitation process, which led to REE exchange in the igneous fluorapatite and hydrothermal monazite. In Type I local alteration, La and Pr-Nd show continuity across the pre- and post- alteration concentric zones indicating that they were not affected by alteration. This is an example of a selective elemental exchange during coupled dissolution-precipitation. Type II, pervasive post-growth alteration, is evident by the presence of micro-porosity and the formation of secondary, reaction induced minerals. Release of HREE from the monazite goes into the formation of void filling xenotime inclusions; the first documentation of this metasomatic alteration product in monazite. A well-documented discrepancy exists among ages determined from the zircon, fluorapatite, monazite, and altered porphyry minerals. These observations, regarding selective alteration of fluorapatite and monazite, may help to elucidate the reasons for this discrepancy.

Fiber optic detector and method for using same for detecting chemical species

DOEpatents

Baylor, Lewis C.; Buchanan, Bruce R.

1995-01-01

An optical sensing device for uranyl and other substances, a method for making an optical sensing device and a method for chemically binding uranyl and other indicators to glass, quartz, cellulose and similar substrates. The indicator, such as arsenazo III, is immobilized on the substrate using a chemical binding process. The immobilized arsenazo III causes uranyl from a fluid sample to bind irreversibly to the substrate at its active sites, thus causing absorption of a portion of light transmitted through the substrate. Determination of the amount of light absorbed, using conventional means, yields the concentration of uranyl present in the sample fluid. The binding of uranyl on the substrate can be reversed by subsequent exposure of the substrate to a solution of 2,6-pyridinedicarboxylic acid. The chemical binding process is suitable for similarly binding other indicators, such as bromocresol green.

Putty-like bone fillers based on CaP ceramics or Biosilicate® combined with carboxymethylcellulose: Characterization, optimization, and evaluation.

PubMed

Gabbai-Armelin, Paulo R; Renno, Ana Cm; Crovace, Murilo C; Magri, Angela Mp; Zanotto, Edgar D; Peitl, Oscar; Leeuwenburgh, Sander Cg; Jansen, John A; van den Beucken, Jeroen Jjp

2017-08-01

Calcium phosphates and bioactive glass ceramics have been considered promising biomaterials for use in surgeries. However, their moldability should be further enhanced. We here thereby report the handling, physicochemical features, and morphological characteristics of formulations consisting of carboxymethylcellulose-glycerol and hydroxyapatite-tricalcium phosphate or Biosilicate® particles. We hypothesized that combining either material with carboxymethylcellulose-glycerol would improve handling properties, retaining their bioactivity. In addition to scanning electron microscopy, cohesion, mineralization, pH, and viscoelastic properties of the novel formulations, cell culture experiments were performed to evaluate the cytotoxicity and cell proliferation. Putty-like formulations were obtained with improved cohesion and moldability. Remarkably, mineralization in simulated body fluid of hydroxyapatite-tricalcium phosphate/carboxymethylcellulose-glycerol formulations was enhanced compared to pure hydroxyapatite-tricalcium phosphate. Cell experiments showed that all formulations were noncytotoxic and that HA-TCP60 and BGC50 extracts led to an increased cell proliferation. We conclude that combining carboxymethylcellulose-glycerol with either hydroxyapatite-tricalcium phosphate or Biosilicate® allows for the generation of moldable putties, improves handling properties, and retains the ceramic bioactivity.

Osteoblast response to zirconia-hybridized pyrophosphate-stabilized amorphous calcium phosphate

PubMed Central

Whited, Bryce M.; Skrtic, Drago; Love, Brian J.

2006-01-01

Calcium phosphate bioceramics, such as hydroxyapatite, have long been used as bone substitutes because of their proven biocompatibility and bone binding properties in vivo. Recently, a zirconia-hybridized pyrophosphate-stabilized amorphous calcium phosphate (Zr-ACP) has been synthesized, which is more soluble than hydroxyapatite and allows for controlled release of calcium and phosphate ions. These ions have been postulated to increase osteoblast differentiation and mineralization in vitro. The focus of this work is to elucidate the physicochemical properties of Zr-ACP and to measure cell response to Zr-ACP in vitro using a MC3T3-E1 mouse calvarial-derived osteoprogenitor cell line. Cells were cultured in osteogenic medium and mineral was added to culture at different stages in cell maturation. Culture in the presence of Zr-ACP showed significant increases in cell proliferation, alkaline phosphatase activity (ALP), and osteopontin (OPN) synthesis, whereas collagen synthesis was unaffected. In addition, calcium and phosphate ion concentrations and medium pH were found to transiently increase with the addition of Zr-ACP, and are hypothesized to be responsible for the osteogenic effect of Zr-ACP. PMID:16278876

Raman spectroscopic study of the mineral qingheiite Na2(Mn2+,Mg,Fe2+)2(Al,Fe3+)(PO4)3, a pegmatite phosphate mineral from Santa Ana pegmatite, Argentina.

PubMed

Frost, Ray L; Xi, Yunfei; Scholz, Ricardo; López, Andrés; Moreira, Caio; de Lena, Jorge Carvalho

2013-10-01

The pegmatite mineral qingheiite Na2(Mn(2+),Mg,Fe(2+))2(Al,Fe(3+))(PO4)3 has been studied by a combination of SEM and EMP, Raman and infrared spectroscopy. The studied sample was collected from the Santa Ana pegmatite, Argentina. The mineral occurs as a primary mineral in lithium bearing pegmatite, in association with beausite and lithiophilite. The Raman spectrum is characterized by a very sharp intense Raman band at 980 cm(-1) assigned to the PO4(3-) symmetric stretching mode. Multiple Raman bands are observed in the PO4(3-) antisymmetric stretching region, providing evidence for the existence of more than one phosphate unit in the structure of qingheiite and evidence for the reduction in symmetry of the phosphate units. This concept is affirmed by the number of bands in the ν4 and ν2 bending regions. No intensity was observed in the OH stretching region in the Raman spectrum but significant intensity is found in the infrared spectrum. Infrared bands are observed at 2917, 3195, 3414 and 3498 cm(-1) are assigned to water stretching vibrations. It is suggested that some water is coordinating the metal cations in the structure of qingheiite. Copyright © 2013 Elsevier B.V. All rights reserved.

75 FR 36701 - Issuance of Environmental Assessment and Finding of No Significant Impact for Modification of...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-28

... in the form of highly water soluble uranyl fluoride. EnergySolutions also proposed the addition of...; the concentration of residual uranyl fluoride in the K-25 piping waste in the railcars would likely... soluble uranyl fluoride in quantities in excess of the limits in Condition 4 of the 2006 Order (i.e., up...

Determination of phosphorus fertilizer soil reactions by Raman and synchrotron infrared microspectroscopy.

PubMed

Vogel, Christian; Adam, Christian; Sekine, Ryo; Schiller, Tara; Lipiec, Ewelina; McNaughton, Don

2013-10-01

The reaction mechanisms of phosphate-bearing mineral phases from sewage sludge ash-based fertilizers in soil were determined by Raman and synchrotron infrared microspectroscopy. Different reaction mechanisms in wet soil were found for calcium and magnesium (pyro-) phosphates. Calcium orthophosphates were converted over time to hydroxyapatite. Conversely, different magnesium phosphates were transformed to trimagnesium phosphate. Since the magnesium phosphates are unable to form an apatite structure, the plant-available phosphorus remains in the soil, leading to better growth results observed in agricultural pot experiments. The pyrophosphates also reacted very differently. Calcium pyrophosphate is unreactive in soil. In contrast, magnesium pyrophosphate quickly formed plant-available dimagnesium phosphate.

Evidence of a Nonphotochemical Mechanism for the Solid-State Formation of Uranyl Peroxide.

PubMed

Kirkegaard, Marie C; Miskowiec, Andrew; Ambrogio, Michael W; Anderson, Brian B

2018-05-21

We have demonstrated the solid-state formation of a uranyl peroxide (UP) species from hydrated uranyl fluoride via a uranyl hydroxide intermediate, the first observation of a UP species formed in a solid-state reaction. Water vapor pressure is shown to be a driving factor of both the loss of fluorine and the subsequent formation of peroxo units. We have ruled out a photochemical mechanism for formation of the UP species by demonstrating that the same reaction occurs in the dark. A radiolytic mechanism is unlikely because of the low radioactivity of the sample material, suggesting the existence of a novel UP formation mechanism.

METHOD OF INHIBITING CORROSION IN URANYL SULFATE SOLUTIONS

DOEpatents

Bohlmann, E.G.; Griess, J.C. Jr.

1960-08-23

A method is given for treating a uranyl sulfate solution to inhibit the corrosiveness of the solution and elevate the phase separation temperature of the solution. Lithium sulfate is added to the solution in an amount ranging from 0.25 to 1.3 times the uranyl sulfate concentration. The corrosiveness of the solution with respect to stainless steel is substantially decreased by this means. This treatment also serves to raise the phase separation temperature of the solution (above 250 deg C), at which time the uranyl sulfate solution separates into two liquid phases of unequal uranium concentration and thus becomes unsuitable as nuclear reactor fuel.

Characterization of UO2(2+) binding to osteopontin, a highly phosphorylated protein: insights into potential mechanisms of uranyl accumulation in bones.

PubMed

Qi, Lei; Basset, Christian; Averseng, Olivier; Quéméneur, Eric; Hagège, Agnès; Vidaud, Claude

2014-01-01

Bones are one of the few organs in which uranyl (UO2(2+)) accumulates. This large dioxo-cation displays affinity for carboxylates, phenolates and phosphorylated functional groups in proteins. The noncollagenous protein osteopontin (OPN) plays an important role in bone homeostasis. It is mainly found in the extracellular matrix of mineralized tissues but also in body fluids such as milk, blood and urine. Furthermore, OPN is an intrinsically disordered protein, which, like other proteins of the SIBLING family, contains a polyaspartic acid sequence and numerous patterns of alternating acidic and phosphorylated residues. All these properties led to the hypothesis that this protein could be prone to UO2(2+) binding. In this work, a simple purification procedure enabling highly purified bovine (bOPN) and human OPN (hOPN) to be obtained was developed. Various biophysical approaches were set up to study the impact of phosphorylations on the affinity of OPN for UO2(2+) as well as the formation of stable complexes originating from structural changes induced by the binding of this metal cation. The results obtained suggest a new mechanism of the interaction of UO2(2+) with bone metabolism and a new role for OPN as a metal transporter.

The mineral phase in the cuticles of two species of Crustacea consists of magnesium calcite, amorphous calcium carbonate, and amorphous calcium phosphate.

PubMed

Becker, Alexander; Ziegler, Andreas; Epple, Matthias

2005-05-21

The cuticules (shells) of the woodlice Porcellio scaber and Armadillidium vulgare were analysed with respect to their content of inorganic material. It was found that the cuticles consist of crystalline magnesium calcite, amorphous calcium carbonate (ACC), and amorphous calcium phosphate (ACP), besides small amounts of water and an organic matrix. It is concluded that the cuticle, which constitutes a mineralized protective organ, is chemically adapted to the biological requirements by this combination of different materials.

Nanobacteria: Fact or Fiction? Characteristics, Detection and Medical Importance of Novel Self-Replicating, Calcifying Nanoparticles

NASA Technical Reports Server (NTRS)

Ciftcioglu, Neva; Mckay, David S.; Mathew, Grace; Kajander, E. Olavi

2006-01-01

There is some debate in microbiology as to whether Nanobacteria (NB) are alive. This paper reviews some aspects of NB. In summary, Nanobacteria is a perfect model for studying biogenic mineralization/calcification because NB a) are self-replicating particles and have less complicated metabolic pathways b) accumulate calcium and phosphate under physiological conditions, c)produce a calcium phosphate mineral similar to bone, d) exist in physical conditions (pH, gravity, temperature, etc) that are easy to manipulate, and which can be replicated for the physiological model.

Polyphosphate-Accumulating Bacteria: Potential Contributors to Mineral Dissolution in the Oral Cavity

PubMed Central

Breiland, Ashley A.; Flood, Beverly E.; Nikrad, Julia; Bakarich, John; Husman, Matthew; Rhee, TaekHyun; Jones, Robert S.

2018-01-01

ABSTRACT Bacteria that accumulate polyphosphates have previously been shown to dynamically influence the solubility of phosphatic minerals in marine settings and wastewater. Here, we show that dental plaque, saliva, and carious lesions all contain abundant polyphosphate-accumulating bacteria. Saturation state modeling results, informed by phosphate uptake experiments using the model organism Lactobacillus rhamnosus, which is known to inhabit advanced carious lesions, suggest that polyphosphate accumulation can lead to undersaturated conditions with respect to hydroxyapatite under some oral cavity conditions. The cell densities of polyphosphate-accumulating bacteria we observed in some regions of oral biofilms are comparable to those that produce undersaturated conditions (i.e., those that thermodynamically favor mineral dissolution) in our phosphate uptake experiments with L. rhamnosus. These results suggest that the localized generation of undersaturated conditions by polyphosphate-accumulating bacteria constitutes a new potential mechanism of tooth dissolution that may augment the effects of metabolic acid production. IMPORTANCE Dental caries is a serious public health issue that can have negative impacts on overall quality of life and oral health. The role of oral bacteria in the dissolution of dental enamel and dentin that can result in carious lesions has long been solely ascribed to metabolic acid production. Here, we show that certain oral bacteria may act as a dynamic shunt for phosphate in dental biofilms via the accumulation of a polymer known as polyphosphate—potentially mediating phosphate-dependent conditions such as caries (dental decay). PMID:29352083

Enhanced attenuation of septic system phosphate in noncalcareous sediments.

PubMed

Robertson, W D

2003-01-01

Review of phosphate behavior in four mature septic system plumes on similar textured sand has revealed a strong correlation between carbonate mineral content and phosphate concentrations. A plume on calcareous sand (Cambridge site, 27 wt % CaCO3 equiv.) has proximal zone PO4 concentrations (4.8 mg/L P average) that are about 75% of the septic tank effluent value, whereas three plumes on noncalcareous sand (Muskoka, L. Joseph, and Nobel sites, <1 wt % CaCO3 equiv.) have proximal zone phosphate concentrations (<0.1 mg/L P) that are consistently less than 2% of the effluent values. Phosphate attenuation at the noncalcareous sites appears to be an indirect result of the development of acidic conditions (site average pH 3.5 to 5.9) and elevated Al concentrations (up to 24 mg/L), which subsequently causes the precipitation of Al-P minerals such as variscite (AlPO4 x 2H2O). This is supported by scanning electron microscope analyses, which show the widespread occurrence of (Al+P)--rich secondary mineral coatings on sand grains below the infiltration beds. All of these septic systems are more than 10 years old, indicating that these attenuation reactions have substantial longevity. A field lysimeter experiment demonstrated that this reaction sequence can be readily incorporated into engineered waste water treatment systems. We feel this important P removal mechanism has not been adequately recognized, particularly for its potential significance in reducing P loading from septic systems in lakeshore environments.

Octreotide Is Ineffective in Treating Tumor-Induced Osteomalacia: Results of a Short-Term Therapy.

PubMed

Ovejero, Diana; El-Maouche, Diala; Brillante, Beth A; Khosravi, Azar; Gafni, Rachel I; Collins, Michael T

2017-08-01

Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome in which unregulated hypersecretion of fibroblast growth factor 23 (FGF23) by phosphaturic mesenchymal tumors (PMT) causes renal phosphate wasting, hypophosphatemia, and osteomalacia. The resulting mineral homeostasis abnormalities and skeletal manifestations can be reversed with surgical resection of the tumor. Unfortunately, PMTs are often difficult to locate, and medical treatment with oral phosphate and vitamin D analogues is either insufficient to manage the disease or not tolerated. Octreotide has been proposed as a potential treatment for TIO due to the presence of somatostatin receptors (SSTR) on PMTs; however, the role of somatostatin signaling in PMTs and the efficacy of treatment of TIOs with somatostatin analogues is not clear. In an effort to evaluate the efficacy of octreotide therapy in TIO, five subjects with TIO were treated with octreotide for 3 days. Blood intact FGF23, phosphate, and 1,25(OH) 2 D 3 , and tubular reabsorption of phosphate (TRP) were measured at frequent time points during treatment. Octreotide's effects were assessed by comparing group means of the biochemical parameters at each time-point to mean baseline values. There were no significant changes in blood phosphate, FGF23, 1,25(OH) 2 D 3 , or TRP during octreotide treatment, consistent with a lack of efficacy of octreotide in treating TIO. © 2017 American Society for Bone and Mineral Research. © 2017 American Society for Bone and Mineral Research.

Backfill composition for secondary barriers in nuclear waste repositories

DOEpatents

Beall, Gary W.; Allard, Bert M.

1982-01-01

A backfill composition for sorbing and retaining hazardous elements of nuclear wastes comprises 50-70% by weight of quartz, 10-30% by weight of montmorillonite, 1-10% by weight of phosphate mineral, 1-10% by weight of ferrous mineral, 1-10% by weight of sulfate mineral and 1-10% by weight of attapulgite.

Fourier transform infrared spectroscopic imaging parameters describing acid phosphate substitution in biologic hydroxyapatite.

PubMed

Spevak, Lyudmila; Flach, Carol R; Hunter, Tracey; Mendelsohn, Richard; Boskey, Adele

2013-05-01

Acid phosphate substitution into mineralized tissues is an important determinant of their mechanical properties and their response to treatment. This study identifies and validates Fourier transform infrared spectroscopic imaging (FTIRI) spectral parameters that provide information on the acid phosphate (HPO4) substitution into hydroxyapatite in developing mineralized tissues. Curve fitting and Fourier self-deconvolution were used to identify subband positions in model compounds (with and without HPO4). The intensity of subbands at 1127 and 1110 cm(-1) correlated with the acid phosphate content in these models. Peak height ratios of these subbands to the ν3 vibration at 1096 cm(-1) found in stoichiometric apatite were evaluated in the model compounds and mixtures thereof. FTIRI spectra of bones and teeth at different developmental ages were analyzed using these spectral parameters. Factor analysis (a chemometric technique) was also conducted on the tissue samples and resulted in factor loadings with spectral features corresponding to the HPO4 vibrations described above. Images of both factor correlation coefficients and the peak height ratios 1127/1096 and 1112/1096 cm(-1) demonstrated higher acid phosphate content in younger vs. more mature regions in the same specimen. Maps of the distribution of acid phosphate content will be useful for characterizing the extent of new bone formation, the areas of potential decreased strength, and the effects of therapies such as those used in metabolic bone diseases (osteoporosis, chronic kidney disease) on mineral composition. Because of the wider range of values obtained with the 1127/1096 cm(-1) parameter compared to the 1110/1096 cm(-1) parameter and the smaller scatter in the slope, it is suggested that this ratio should be the parameter of choice.

FTIRI Parameters describing Acid Phosphate Substitution in Biologic Hydroxyapatite

PubMed Central

Spevak, Lyudmila; Flach, Carol R.; Hunter, Tracey; Mendelsohn, Richard; Boskey, Adele

2013-01-01

Acid phosphate substitution into mineralized tissue is an important determinant of their mechanical properties and their response to treatment. This study identifies and validates Fourier Transform Infrared Spectroscopic Imaging (FTIRI) spectral parameters that provide information on the acid phosphate (HPO4) substitution into hydroxyapatite in developing mineralized tissues. Curve fitting and Fourier self-deconvolution were used to identify subband positions in model compounds (with and without HPO4). The intensity of subbands at 1127 cm−1 and 1110 cm−1 correlated with the acid phosphate content in these models. Peak height ratios of these subbands to the ν3 vibration at 1096 cm−1 found in stoichiometric apatite, were evaluated in the model compounds and mixtures thereof. FTIRI spectra of bones and teeth at different developmental ages were analyzed using these spectral parameters. Factor analysis (a chemometric technique) was also conducted on the tissue samples and resulted in factor loadings with spectral features corresponding to the HPO4 vibrations described above. Images of both factor correlation coefficients and the peak height ratios 1127cm−1/1096cm−1 and 1112cm−1/1096cm−1 demonstrated higher acid phosphate content in younger vs. more mature regions in the same specimen. Maps of the distribution of acid phosphate content will be useful for characterizing the extent of new bone formation, areas of potential decreased strength, and the effects of therapies such as those used in metabolic bone diseases (osteoporosis, chronic kidney disease) on mineral composition. Because of the wider range of values obtained with the 1127 cm−1/1096 cm−1 parameter compared to the 1110 cm−1/1096 cm−1 parameter, and the smaller scatter in the slope, it is suggested that this ratio should be the parameter of choice. PMID:23380987

Origin of sulfide and phosphate deposits in Upper Proterozoic carbonate strata, Irece basin, Bahia, Brazil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kyle, J.R.; Misi, A.

1991-03-01

Carbonate strata of the Una Group represent late Proterozoic platform sedimentation in the Irece basin of north-central Brazil. Stratabound sulfide- and phosphate-rich units occur within a 50-m thick tidal flat sequence of dolomitic limestone and cherty dolomite. Three types of primary phosphate concentrations are present: columnar stromatolitic, laminar stromatolitic, and intraclastic. Resedimented phosphate clasts and phosphatic units interbedded with non phosphatic dolomites suggest early diagenetic replacement of algal carbonate units. Local stratabound Zn-Pb-Ag sulfide concentrations at the Tres Irmas prospect occur within silty dolomite with shallow water sedimentary structures and local disturbed laminae, synsedimentary faults, and breccias. Sulfide minerals includemore » pyrite, sphalerite, galena, marcasite, jordanite, tetrahedrite, and covellite. Pyrite crystal aggregates commonly show bladed forms. Nodular aggregates of length-slow quartz are locally associated with sulfides. Sulfur isotope analyses indicate relatively uniform heavy {delta}{sup 34}S values. Barite shows a {delta}{sup 34}S range from +25.2 to +29.6{per thousand}, CDT. Pyrite and sphalerite representative of a variety of textural types have a {delta}{sup 34}S range of +20.2 to +22.6{per thousand}. Late Proterozoic evaporite sulfates show a wide range of {delta}{sup 34} S values from about +10 to +28{per thousand}. Thus, the {delta}{sup 34}S values for Irece barite could reflect original seawater sulfate values. However, the relatively heavy {delta}{sup 34}S values of the associated sulfides suggests that the original seawater sulfate was modified by bacterial sulfate reduction processes in shallow sea floor sediments. Textural and {delta}{sup 34}S evidence suggests that a later stage of metallic mineralization scavenged sulfur from preexisting sulfides or from direct reduction of evaporitic sulfate minerals.« less

[Impact of the area burden of agrochemicals on tuberculosis morbidity and mortality].

PubMed

Onishchenko, G G; Mamaev, I A; Guseĭnov, G K

2006-01-01

The rate of use of pesticides and mineral fertilizers in the Republic of Daghestan was high in the USSR and Russia and was many times greater than the critical burden (3/93 kg/ha) and ranged from 3.5-4.2 kg/ha in the highlands to 17.0-21.7 kg/ha in the plain. Two-factor analysis indicated that out of the mineral fertilizers, pesticides and phosphate fertilizers had the most adverse effect on the incidence of tuberculosis whereas potash fertilizers exerted a less effect. Phosphate fertilizers and copper-containing pesticides were secondary risk factors of death from tuberculosis. The correlation coefficient was 0.53 for phosphate fertilizers, 0.59 upon total exposure to organochlorine compounds, and 0.68 upon total exposure to copper-containing pesticides.

Fourier transform infrared imaging of femoral neck bone: reduced heterogeneity of mineral-to-matrix and carbonate-to-phosphate and more variable crystallinity in treatment-naive fracture cases compared with fracture-free controls.

PubMed

Gourion-Arsiquaud, Samuel; Lukashova, Lyudmilla; Power, Jon; Loveridge, Nigel; Reeve, Jonathan; Boskey, Adele L

2013-01-01

After the age of 60 years, hip fracture risk strongly increases, but only a fifth of this increase is attributable to reduced bone mineral density (BMD, measured clinically). Changes in bone quality, specifically bone composition as measured by Fourier transform infrared spectroscopic imaging (FTIRI), also contribute to fracture risk. Here, FTIRI was applied to study the femoral neck and provide spatially derived information on its mineral and matrix properties in age-matched fractured and nonfractured bones. Whole femoral neck cross sections, divided into quadrants along the neck's axis, from 10 women with hip fracture and 10 cadaveric controls were studied using FTIRI and micro-computed tomography. Although 3-dimensional micro-CT bone mineral densities were similar, the mineral-to-matrix ratio was reduced in the cases of hip fracture, confirming previous reports. New findings were that the FTIRI microscopic variation (heterogeneity) of the mineral-to-matrix ratio was substantially reduced in the fracture group as was the heterogeneity of the carbonate-to-phosphate ratio. Conversely, the heterogeneity of crystallinity was increased. Increased variation of crystallinity was statistically associated with reduced variation of the carbonate-to-phosphate ratio. Anatomical variation in these properties between the different femoral neck quadrants was reduced in the fracture group compared with controls. Although our treatment-naive patients had reduced rather than increased bending resistance, these changes in heterogeneity associated with hip fracture are in another way comparable to the effects of experimental bisphosphonate therapy, which decreases heterogeneity and other indicators of bone's toughness as a material. Copyright © 2013 American Society for Bone and Mineral Research.

Phosphorus Equilibria Among Mafic Silicate Phases

NASA Technical Reports Server (NTRS)

Berlin, Jana; Xirouchakis, Dimitris

2002-01-01

Phosphorus incorporation in major rock-forming silicate minerals has the following implications: (1) Reactions between phosphorus-hosting major silicates and accessory phosphates, which are also major trace element carriers, may control the stability of the latter and thus may affect the amount of phosphorus and other trace elements released to the coexisting melt or fluid phase. (2) Less of a phosphate mineral is needed to account for the bulk phosphorus of planetaty mantles. (3) During partial melting of mantle mineral assemblages or equilibrium fractional crystallization of basaltic magmas, and in the absence or prior to saturation with a phosphate mineral, silicate melts may become enriched in phosphorus, especially in the geochemically important low melt fraction regime, Although the small differences in the ionic radii of IVp5+, IVSi4+, and IV Al3+ makes phosphoms incorporation into crystalline silicates perhaps unsurprising, isostructural silicate and phosphate crystalline solids do not readily form solutions, e.g., (Fe, Mg)2SiO4 vs. LiMgPO4, SiO)2 VS. AlPO4. Nonetheless, there are reports of, poorly characterized silico-phosphate phases in angrites , 2-4 wt% P2O5 in olivine and pyroxene grains in pallasites and reduced terestrial basalts which are little understood but potentially useful, and up to 17 wt% P2O5 in olivine from ancient slags. However, such enrichments are rare and only underscore the likelihood of phosphoms incorporation in silicate minerals. The mechanisms that allow phosphorus to enter major rock-forming silicate minerals (e.g., Oliv, Px, Gt) remain little understood and the relevant data base is limited. Nonetheless, old and new high-pressure (5-10 GPa) experimental data suggest that P2O5 wt% decreases from silica-poor to silica-rich compositions or from orthosilicate to chain silicate structures (garnet > olivine > orthopyroxene) which implies that phosphorus incorporation in silicates is perhaps more structure-than site-specific. The data also indicate that DXVliQP2O5 decrease in the same order, but DOVLiQP2O5 and DOpx/LiQP205 are likely constant, respectively equal to 0.08(3) and 0.007(4), in contrast, DG1ILiQP205 increases from 0.15(3) to 0.36(10) as garnet becomes majoritic, thus silica-enriched, and may also depend on liquid composition (SiO2, P2O5 and Na2O wt%).

Contributions of Phosphorus from Groundwater to Streams in the Piedmont, Blue Ridge, and Valley and Ridge Physiographic Provinces, Eastern United States

USGS Publications Warehouse

Denver, Judith M.; Cravotta,, Charles A.; Ator, Scott W.; Lindsey, Bruce D.

2011-01-01

Phosphorus from natural and human sources is likely to be discharged from groundwater to streams in certain geochemical environments. Water-quality data collected from 1991 through 2007 in paired networks of groundwater and streams in different hydrogeologic and land-use settings of the Piedmont, Blue Ridge, and Valley and Ridge Physiographic Provinces in the eastern United States were compiled and analyzed to evaluate the sources, fate, and transport of phosphorus. The median concentrations of phosphate in groundwater from the crystalline and siliciclastic bedrock settings (0.017 and 0.020 milligrams per liter, respectively) generally were greater than the median for the carbonate setting (less than 0.01 milligrams per liter). In contrast, the median concentrations of dissolved phosphate in stream base flow from the crystalline and siliciclastic bedrock settings (0.010 and 0.014 milligrams per liter, respectively) were less than the median concentration for base-flow samples from the carbonate setting (0.020 milligrams per liter). Concentrations of phosphorus in many of the stream base-flow and groundwater samples exceeded ecological criteria for streams in the region. Mineral dissolution was identified as the dominant source of phosphorus in the groundwater and stream base flow draining crystalline or siliciclastic bedrock in the study area. Low concentrations of dissolved phosphorus in groundwater from carbonate bedrock result from the precipitation of minerals and (or) from sorption to mineral surfaces along groundwater flow paths. Phosphorus concentrations are commonly elevated in stream base flow in areas underlain by carbonate bedrock, however, presumably derived from in-stream sources or from upland anthropogenic sources and transported along short, shallow groundwater flow paths. Dissolved phosphate concentrations in groundwater were correlated positively with concentrations of silica and sodium, and negatively with alkalinity and concentrations of calcium, magnesium, chloride, nitrate, sulfate, iron, and aluminum. These associations can result from the dissolution of alkali feldspars containing phosphorus; the precipitation of apatite; the precipitation of calcite, iron hydroxide, and aluminum hydroxide with associated sorption of phosphate ions; and the potential for release of phosphate from iron-hydroxide and other iron minerals under reducing conditions. Anthropogenic sources of phosphate such as fertilizer and manure and processes such as biological uptake, evapotranspiration, and dilution also affect phosphorus concentrations. The phosphate concentrations in surface water were not correlated with the silica concentration, but were positively correlated with concentrations of major cations and anions, including chloride and nitrate, which could indicate anthropogenic sources and effects of evapotranspiration on surface-water quality. Mixing of older, mineralized groundwater with younger, less mineralized, but contaminated groundwater was identified as a critical factor affecting the quality of stream base flow. In-stream processing of nutrients by biological processes also likely increases the phosphorus concentration in surface waters. Potential geologic contributions of phosphorus to groundwater and streams may be an important watershed-management consideration in certain hydrogeologic and geochemical environments. Geochemical controls effectively limit phosphorus transport through groundwater to streams in areas underlain by carbonate rocks; however, in crystalline and siliciclastic settings, phosphorus from mineral or human sources may be effectively transported by groundwater and contribute a substantial fraction to base-flow stream loads.

Phosphorus minerals in tonstein; coal seam 405 at Sośnica-Makoszowy coal mine, Upper Silesia, southern Poland

NASA Astrophysics Data System (ADS)

Kokowska-Pawłowska, Magdalena; Nowak, Jacek

2013-06-01

Kokowska-Pawłowska, M. and Nowak, J. 2013. Phosphorus minerals in tonstein; coal seam 405 at Sośnica- Makoszowy coal mine, Upper Silesia, southern Poland. Acta Geologica Polonica, 63 (2), 271-281. Warszawa. The paper presents results of research on tonstein, which constitutes an interburden in coal seam 405 at the Sośnica- Makoszowy coal mine, Makoszowy field (mining level 600 m), Upper Silesia, southern Poland. The mineral and chemical compositions of the tonstein differ from the typical compositions described earlier for tonsteins from Upper Silesia Coal Basin area. Additionally, minerals present in the tonsteins include kaolinite, quartz, kaolinitised biotite and feldspars. The presence of the phosphatic minerals apatite and goyazite has been recognized. The presence of gorceixite and crandallite is also possible. The contents of CaO (5.66 wt%) and P2O5 (6.2 wt%) are remarkably high. Analysis of selected trace elements demonstrated high contents of Sr (4937 ppm) and Ba (4300 ppm), related to the phosphatic minerals. On the basis of mineral composition the tonstein has been identified as a crystalline tonstein, transitional to a multiplied one.

Complementary Enzymes Activities in Organic Phosphorus Mineralization and Cycling by Phosphohydrolases in Soils

USDA-ARS?s Scientific Manuscript database

Inorganic and organic phosphates react strongly with soil constituents, resulting in relatively low concentrations of soluble phosphates in the soil solution. Multiple competing reactions control the solution-phase concentration and the cycling of phosphorus-containing organic substrates and the re...

Mineral phosphate solubilization by Streptomyces sp. CTM396 involves the excretion of gluconic acid and is stimulated by humic acids.

PubMed

Farhat, Mounira Ben; Boukhris, Ines; Chouayekh, Hichem

2015-03-01

The actinomycetes isolates (128) which were taken from agricultural soil samples and collected near a rock phosphate processing unit were screened for mineral phosphate-solubilizing (MPS) ability. A significant MPS activity was observed for 30 isolates on various phosphate sources when grown in the National Botanical Research Institute's phosphate broth. CTM396 and CTM397 strains which showed the highest MPS abilities were identified by 16S rDNA sequencing as members of the genus Streptomyces. Their MPS activity was proved to be concomitant with a drop in pH due to the secretion of gluconic acid (GA). This was correlated with the simultaneous detection by PCR of genes gdh [encoding the glucose dehydrogenase (GDH) responsible for GA production from glucose] and pqq (involved in biosynthesis of the pyrroloquinoline quinone cofactor of GDH), as well as the highlighting of GHD enzyme activity, for the first time in a Streptomyces sp. strain producing GA. Furthermore, the 0.05% of humic acids proved to have a stimulatory effect on the growth and the ability of CTM396 to solubilize Gafsa rock phosphate. According to this study, it is possible to use humic acids and Gafsa rock phosphate in association with spores of ad hoc Streptomyces strains as natural and efficient amendments to improve plant growth with no need of costly and pollutant transformation of Gafsa rock phosphate. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

[Metabolic bone disease osteomalacia].

PubMed

Reuss-Borst, M A

2014-05-01

Osteomalacia is a rare disorder of bone metabolism leading to reduced bone mineralization. Underlying vitamin D deficiency and a disturbed phosphate metabolism (so-called hypophosphatemic osteomalacia) can cause the disease. Leading symptoms are dull localized or generalized bone pain, muscle weakness and cramps as well as increased incidence of falls. Rheumatic diseases, such as polymyalgia rheumatica, rheumatoid arthritis, myositis and fibromyalgia must be considered in the differential diagnosis. Alkaline phosphatase (AP) is typically elevated in osteomalacia while serum phosphate and/or 25-OH vitamin D3 levels are reduced. The diagnosis of osteomalacia can be confirmed by an iliac crest bone biopsy. Histological correlate is reduced or deficient mineralization of the newly synthesized extracellular matrix. Treatment strategies comprise supplementation of vitamin D and calcium and for patients with intestinal malabsorption syndromes vitamin D and calcium are also given parenterally. In renal phosphate wasting syndromes substitution of phosphate is the treatment of choice, except for tumor-induced osteomalacia when removal of the tumor leads to a cure in most cases.

Phosphine from rocks: mechanically driven phosphate reduction?

PubMed

Glindemann, Dietmar; Edwards, Marc; Morgenstern, Peter

2005-11-01

Natural rock and mineral samples released trace amounts of phosphine during dissolution in mineral acid. An order of magnitude more phosphine (average 1982 ng PH3 kg rock and maximum 6673 ng PH3/kg rock) is released from pulverized rock samples (basalt, gneiss, granite, clay, quartzitic pebbles, or marble). Phosphine was correlated to hardness and mechanical pulverization energy of the rocks. The yield of PH3 ranged from 0 to 0.01% of the total P content of the dissolved rock. Strong circumstantial evidence was gathered for reduction of phosphate in the rock via mechanochemical or "tribochemical" weathering at quartz and calcite/marble inclusions. Artificial reproduction of this mechanism by rubbing quartz rods coated with apatite-phosphate to the point of visible triboluminescence, led to detection of more than 70 000 ng/kg PH3 in the apatite. This reaction pathway may be considered a mechano-chemical analogue of phosphate reduction from lightning or electrical discharges and may contribute to phosphine production via tectonic forces and processing of rocks.

Survey of the enthesopathy of X-linked hypophosphatemia and its characterization in Hyp mice.

PubMed

Liang, Guoying; Katz, Lee D; Insogna, Karl L; Carpenter, Thomas O; Macica, Carolyn M

2009-09-01

X-linked hypophosphatemia (XLH) is characterized by rickets and osteomalacia as a result of an inactivating mutation of the PHEX (phosphate-regulating gene with homology to endopeptidases on the X chromosome) gene. PHEX encodes an endopeptidase that, when inactivated, results in elevated circulating levels of FGF-23, a novel phosphate-regulating hormone (a phosphatonin), thereby resulting in increased phosphate excretion and impaired bone mineralization. A generalized and severe mineralizing enthesopathy in patients with XLH was first reported in 1985; we likewise report a survey in which we found evidence of enthesopathy in fibrocartilaginous insertion sites, as well as osteophyte formation, in the majority of patients. Nonetheless, there has been very little focus on the progression and pathogenesis underlying the paradoxical heterotopic calcification of tendon and ligament insertion sites. Such studies have been hampered by lack of a model of mineralizing enthesopathy. We therefore characterized the involvement of the most frequently targeted fibrocartilaginous tendon insertion sites in Hyp mice, a murine model of the XLH mutation that phenocopies the human syndrome in every detail including hypophosphatemia and elevated FGF-23. Histological examination of the affected entheses revealed that mineralizing insertion sites, while thought to involve bone spur formation, were not due to bone-forming osteoblasts but instead to a significant expansion of mineralizing fibrocartilage. Our finding that enthesis fibrocartilage cells specifically express fibroblast growth factor receptor 3 (FGFR3)/Klotho suggests that the high circulating levels of FGF-23, characteristic of XLH and Hyp mice, may be part of the biochemical milieu that underlies the expansion of mineralizing enthesis fibrocartilage.

Expanding the Library of Uranyl Amide Derivatives: New Complexes Featuring the tert-Butyldimethylsilylamide Ligand.

PubMed

Pattenaude, Scott A; Coughlin, Ezra J; Collins, Tyler S; Zeller, Matthias; Bart, Suzanne C

2018-04-16

New uranyl derivatives featuring the amide ligand, -N(SiHMe 2 ) t Bu, were synthesized and characterized by X-ray crystallography, multinuclear NMR spectroscopy, and absorption spectroscopies. Steric properties of these complexes were also quantified using the computational program Solid-G. The increased basicity of the free ligand -N(SiHMe 2 ) t Bu was demonstrated by direct comparison to -N(SiMe 3 ) 2 , a popular supporting ligand for uranyl. Substitutional lability on a uranyl center was also demonstrated by exchange with the -N(SiMe 3 ) 2 ligand. The increased basicity of this ligand and diverse characterization handles discussed here will make these compounds useful synthons for future reactivity.

Evidence of a Nonphotochemical Mechanism for the Solid-State Formation of Uranyl Peroxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirkegaard, Marie C.; Miskowiec, Andrew J.; Ambrogio, Michael W.

Here, we have demonstrated the solid-state formation of a uranyl peroxide (UP) species from hydrated uranyl fluoride via a uranyl hydroxide intermediate, the first observation of a UP species formed in a solid-state reaction. Water vapor pressure is shown to be a driving factor of both the loss of fluorine and the subsequent formation of peroxo units. We have ruled out a photochemical mechanism for formation of the UP species by demonstrating that the same reaction occurs in the dark. A radiolytic mechanism is unlikely because of the low radioactivity of the sample material, suggesting the existence of a novelmore » UP formation mechanism.« less

Evidence of a Nonphotochemical Mechanism for the Solid-State Formation of Uranyl Peroxide

DOE PAGES

Kirkegaard, Marie C.; Miskowiec, Andrew J.; Ambrogio, Michael W.; ...

2018-05-10

Here, we have demonstrated the solid-state formation of a uranyl peroxide (UP) species from hydrated uranyl fluoride via a uranyl hydroxide intermediate, the first observation of a UP species formed in a solid-state reaction. Water vapor pressure is shown to be a driving factor of both the loss of fluorine and the subsequent formation of peroxo units. We have ruled out a photochemical mechanism for formation of the UP species by demonstrating that the same reaction occurs in the dark. A radiolytic mechanism is unlikely because of the low radioactivity of the sample material, suggesting the existence of a novelmore » UP formation mechanism.« less

Magnesium Carbonate‐Containing Phosphate Binder Prevents Connective Tissue Mineralization in Abcc6 −/− Mice–Potential for Treatment of Pseudoxanthoma Elasticum

PubMed Central

Li, Qiaoli; LaRusso, Jennifer; Grand‐Pierre, Alix E.; Uitto, Jouni

2009-01-01

Abstract Pseudoxanthoma elasticum (PXE) is a heritable disorder characterized by ectopic mineralization of connective tissues primarily in the skin, eyes, and the cardiovascular system. PXE is caused by mutations in the ABCC6 gene. While PXE is associated with considerable morbidity and mortality, there is currently no effective or specific treatment. In this study, we tested oral phosphate binders for treatment of a mouse model of PXE which we have developed by targeted ablation of the corresponding mouse gene (Abcc6 −/−). This “knock‐out” (KO) mouse model recapitulates features of PXE and demonstrates mineralization of a number of tissues, including the connective tissue capsule surrounding vibrissae in the muzzle skin which serves as an early biomarker of the mineralization process. Treatment of these mice with a magnesium carbonate‐enriched diet (magnesium concentration being 5‐fold higher than in the control diet) completely prevented mineralization of the vibrissae up to 6 months of age, as demonstrated by computerized morphometric analysis of histopathology as well as by calcium and phosphate chemical assays. The magnesium carbonate‐enriched diet also prevented the progression of mineralization when the mice were placed on that experimental diet at 3 months of age and followed up to 6 months of age. Treatment with magnesium carbonate was associated with a slight increase in the serum concentration of magnesium, with no effect on serum calcium and phosphorus levels. In contrast, concentration of calcium in the urine was increased over 10‐fold while the concentration of phosphorus was markedly decreased, being essentially undetectable after long‐term (>4 month) treatment. No significant changes were noted in the serum parathyroid hormone levels. Computerized axial tomography scan of bones in mice placed on magnesium carbonate‐enriched diet showed no differences in the bone density compared to mice on the control diet, and chemical assays showed a small increase in the calcium and phosphate content of the femurs by chemical assay, in comparison to mice on control diet. Similar experiments with another experimental diet supplemented with lanthanum carbonate did not interfere with the mineralization process in Abcc6 −/− mice. These results suggest that magnesium carbonate may offer a potential treatment modality for PXE, a currently intractable disease, as well as for other conditions characterized by ectopic mineralization of connective tissues. PMID:20443931

Magnesium carbonate-containing phosphate binder prevents connective tissue mineralization in Abcc6(-/-) mice-potential for treatment of pseudoxanthoma elasticum.

PubMed

Li, Qiaoli; Larusso, Jennifer; Grand-Pierre, Alix E; Uitto, Jouni

2009-12-01

Pseudoxanthoma elasticum (PXE) is a heritable disorder characterized by ectopic mineralization of connective tissues primarily in the skin, eyes, and the cardiovascular system. PXE is caused by mutations in the ABCC6 gene. While PXE is associated with considerable morbidity and mortality, there is currently no effective or specific treatment. In this study, we tested oral phosphate binders for treatment of a mouse model of PXE which we have developed by targeted ablation of the corresponding mouse gene (Abcc6(-/-)). This "knock-out" (KO) mouse model recapitulates features of PXE and demonstrates mineralization of a number of tissues, including the connective tissue capsule surrounding vibrissae in the muzzle skin which serves as an early biomarker of the mineralization process. Treatment of these mice with a magnesium carbonate-enriched diet (magnesium concentration being 5-fold higher than in the control diet) completely prevented mineralization of the vibrissae up to 6 months of age, as demonstrated by computerized morphometric analysis of histopathology as well as by calcium and phosphate chemical assays. The magnesium carbonate-enriched diet also prevented the progression of mineralization when the mice were placed on that experimental diet at 3 months of age and followed up to 6 months of age. Treatment with magnesium carbonate was associated with a slight increase in the serum concentration of magnesium, with no effect on serum calcium and phosphorus levels. In contrast, concentration of calcium in the urine was increased over 10-fold while the concentration of phosphorus was markedly decreased, being essentially undetectable after long-term (> 4 month) treatment. No significant changes were noted in the serum parathyroid hormone levels. Computerized axial tomography scan of bones in mice placed on magnesium carbonate-enriched diet showed no differences in the bone density compared to mice on the control diet, and chemical assays showed a small increase in the calcium and phosphate content of the femurs by chemical assay, in comparison to mice on control diet. Similar experiments with another experimental diet supplemented with lanthanum carbonate did not interfere with the mineralization process in Abcc6(-/-) mice. These results suggest that magnesium carbonate may offer a potential treatment modality for PXE, a currently intractable disease, as well as for other conditions characterized by ectopic mineralization of connective tissues.

The desorption of antimony(V) from sediments, hydrous oxides, and clay minerals by carbonate, phosphate, sulfate, nitrate, and chloride.

PubMed

Biver, Marc; Krachler, Michael; Shotyk, William

2011-01-01

The desorption of antimony, Sb(V), from two sediment samples by phosphate, carbonate, sulfate, chloride, and nitrate at pH 8 was examined. One highly contaminated sediment sample was taken from an Sb mine (Goesdorf, Luxembourg); the other sample was the certified reference material PACS-2 (marine sediment). Phosphate was found to have a strong mobilizing ability, whereas that of carbonate was in general weaker. For comparison, and to understand better the possible importance of individual components of the sediments, desorption experiments were performed on pure phases (i.e., hydrous oxides of Fe, Mn, and Al) and the clay minerals kaolinite and montmorillonite. In the cases of hydrous metal oxides, Sb(V) was most effectively desorbed by phosphate, followed by carbonate. Phosphate also desorbed Sb(V) from the clay minerals, whereas carbonate had no effect. The pH dependence of adsorption of Sb(V) in the absence and presence of carbonate revealed that adsorption densities were higher (except in the case of montmorillonite) in the absence of carbonate, suggesting a competition between carbonate and [Sb(OH)] for surface sites generally and a lowering of surface charge in the case of hydrous aluminum oxide. The observations are unlikely to be due to ionic strength effects because activity coefficients in the blank and spiked solutions differ by <4%. Desorption experiments on sediments with varying concentrations of phosphate and carbonate demonstrated that at environmentally relevant concentrations, desorption by phosphate is negligible, whereas the effect of carbonate is not. Sulfate, chloride, and nitrate generally had little effect. The proportion of Sb desorbed in blank experiments coincides with that mobilized in the first fraction of the Bureau Communautaire de Référence (BCR) sequential extraction (easily exchangeable and carbonate-bound fraction). Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Influence of substrate rocks on Fe Mn crust composition

NASA Astrophysics Data System (ADS)

Hein, James R.; Morgan, Charles L.

1999-05-01

Principal Component and other statistical analyses of chemical and mineralogical data of Fe-Mn oxyhydroxide crusts and their underlying rock substrates in the central Pacific indicate that substrate rocks do not influence crust composition. Two ridges near Johnston Atoll were dredged repetitively and up to seven substrate rock types were recovered from small areas of similar water depths. Crusts were analyzed mineralogically and chemically for 24 elements, and substrates were analyzed mineralogically and chemically for the 10 major oxides. Compositions of crusts on phosphatized substrates are distinctly different from crusts on substrates containing no phosphorite. However, that relationship only indicates that the episodes of phosphatization that mineralized the substrate rocks also mineralized the crusts that grew on them. A two-fold increase in copper contents in crusts that grew on phosphatized clastic substrate rocks, relative to crusts on other substrate rock types, is also associated with phosphatization and must have resulted from chemical reorganization during diagenesis. Phosphatized crusts show increases in Sr, Zn, Ca, Ba, Cu, Ce, V, and Mo contents and decreases in Fe, Si, and As contents relative to non-phosphatized crusts. Our statistical results support previous studies which show that crust compositions reflect predominantly direct precipitation from seawater (hydrogenetic), and to lesser extents reflect detrital input and diagenetic replacement of parts of the older crust generation by carbonate fluorapatite.

Influence of substrate rocks on Fe-Mn crust composition

USGS Publications Warehouse

Hein, J.R.; Morgan, C.L.

1999-01-01

Principal Component and other statistical analyses of chemical and mineralogical data of Fe-Mn oxyhydroxide crusts and their underlying rock substrates in the central Pacific indicate that substrate rocks do not influence crust composition. Two ridges near Johnston Atoll were dredged repetitively and up to seven substrate rock types were recovered from small areas of similar water depths. Crusts were analyzed mineralogically and chemically for 24 elements, and substrates were analyzed mineralogically and chemically for the 10 major oxides. Compositions of crusts on phosphatized substrates are distinctly different from crusts on substrates containing no phosphorite. However, that relationship only indicates that the episodes of phosphatization that mineralized the substrate rocks also mineralized the crusts that grew on them. A two-fold increase in copper contents in crusts that grew on phosphatized clastic substrate rocks, relative to crusts on other substrate rock types, is also associated with phosphatization and must have resulted from chemical reorganization during diagenesis. Phosphatized crusts show increases in Sr, Zn, Ca, Ba, Cu, Ce, V, and Mo contents and decreases in Fe, Si, and As contents relative to non-phosphatized crusts. Our statistical results support previous studies which show that crust compositions reflect predominantly direct precipitation from seawater (hydrogenetic), and to lesser extents reflect detrital input and diagenetic replacement of parts of the older crust generation by carbonate fluorapatite.

Synthesis and characterization of heterometallic uranyl pyridinedicarboxylate compounds

NASA Astrophysics Data System (ADS)

Jayasinghe, Ashini S.; Payne, Maurice K.; Forbes, Tori Z.

2017-10-01

The incorporation of transition metals into hybrid uranyl materials can result in more diverse structural topologies and variations in physical and chemical properties. To explore the impact of transition metals on the uranyl cation, five uranium containing bimetallic chain compounds, [(UO2)M(PDC)2(H2O)4]·4(H2O) (PDC = 2,6 pyridinedicarboxylate; M = Ni2+, Co2+, Fe2+, Zn2+, and Cu2+) were synthesized by evaporation of aqueous solutions at room temperature. The uranyl cation is complex by two PDC ligands and the transition metal cations bond to the complex to form a one-dimensional chain topology. The presence of the transition metal leads to the presence of a stronger uranyl oxo bonds as shown by the single-crystal X-ray diffraction data and the Raman spectra. Solid state diffuse reflectance UV/Visible spectra confirmed the presence of the transition metals in the structure by the broad bands that appeared at relevant wavelengths.

First Cationic Uranyl-Organic Framework with Anion-Exchange Capabilities.

PubMed

Bai, Zhuanling; Wang, Yanlong; Li, Yuxiang; Liu, Wei; Chen, Lanhua; Sheng, Daopeng; Diwu, Juan; Chai, Zhifang; Albrecht-Schmitt, Thomas E; Wang, Shuao

2016-07-05

By controlling the extent of hydrolysis during the self-assembly process of a zwitterionic-based ligand with uranyl cations, we observed a structural evolution from the neutral uranyl-organic framework [(UO2)2(TTTPC)(OH)O(COOH)]·1.5DMF·7H2O (SCU-6) to the first cationic uranyl-organic framework with the formula of [(UO2)(HTTTPC)(OH)]Br·1.5DMF·4H2O (SCU-7). The crystal structures of SCU-6 and SCU-7 are layers built with tetranuclear and dinuclear uranyl clusters, respectively. Exchangeable halide anions are present in the interlaminar spaces balancing the positive charge of layers in SCU-7. Therefore, SCU-7 is able to effectively remove perrhenate anions from aqueous solution. Meanwhile, the H2PO4(-)-exchanged SCU-7 material exhibits a moderate proton conductivity of 8.70 × 10(-5) S cm(-1) at 50 °C and 90% relative humidity, representing nearly 80 times enhancement compared to the original material.

Structure of selected basic zinc/copper (II) phosphate minerals based upon near-infrared spectroscopy--implications for hydrogen bonding.

PubMed

Frost, Ray L; Reddy, B Jagannadha; Palmer, Sara J; Keeffe, Eloise C

2011-03-01

The NIR spectra of reichenbachite, scholzite and parascholzite have been studied at 298 K. The spectra of the minerals are different, in line with composition and crystal structural variations. Cation substitution effects are significant in their electronic spectra and three distinctly different electronic transition bands are observed in the near-infrared spectra at high wavenumbers in the 12,000-7600 cm(-1) spectral region. Reichenbachite electronic spectrum is characterised by Cu(II) transition bands at 9755 and 7520 cm(-1). A broad spectral feature observed for ferrous ion in the 12,000-9000 cm(-1) region both in scholzite and parascholzite. Some what similarities in the vibrational spectra of the three phosphate minerals are observed particularly in the OH stretching region. The observation of strong band at 5090 cm(-1) indicates strong hydrogen bonding in the structure of the dimorphs, scholzite and parascholzite. The three phosphates exhibit overlapping bands in the 4800-4000 cm(-1) region resulting from the combinations of vibrational modes of (PO(4))(3-) units. Copyright © 2010 Elsevier B.V. All rights reserved.

URANIUM EXTRACTION

DOEpatents

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

1958-07-01

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gibson, John K.; de Jong, Wibe A.; van Stipdonk, Michael J.

In uranyl coordination complexes, UO 2(L) n 2+, uranium in the formally dipositive [O=U=O] 2+ moiety is coordinated by n neutral organic electron donor ligands, L. The extent of ligand electron donation, which results in partial reduction of uranyl and weakening of the U=O bonds, is revealed by the magnitude of the red-shift of the uranyl asymmetric stretch frequency, ν 3 . This phenomenon appears in gas-phase complexes in which uranyl is coordinated by electron donor ligands: the ν 3 red-shift increases as the number of ligands and their proton affinity (PA) increases. Because PA is a measure of themore » enthalpy change associated with a proton-ligand interaction, which is much stronger and of a different nature than metal ion-ligand bonding, it is not necessarily expected that ligand PAs should reliably predict uranyl-ligand bonding and the resulting ν 3 red-shift. In this study, ν 3 was measured for uranyl coordinated by ligands with a relatively broad range of PAs, revealing a surprisingly good correlation between PA and ν 3 frequency. From computed ν 3 frequencies for bare UO 2 cations and neutrals, it is inferred that the effective charge of uranyl in UO 2(L) n 2+ complexes can be reduced to near zero upon ligation by sufficiently strong charge-donor ligands. The basis for the correlation between ν 3 and ligand PAs, as well as limitations and deviations from it, are considered. It is demonstrated that the correlation evidently extends to a ligand that exhibits polydentate metal ion coordination.« less

DFT study of uranyl peroxo complexes with H2O, F-, OH-, CO3(2-), and NO3(-).

PubMed

Odoh, Samuel O; Schreckenbach, Georg

2013-05-06

The structural and electronic properties of monoperoxo and diperoxo uranyl complexes with aquo, fluoride, hydroxo, carbonate, and nitrate ligands have been studied using scalar relativistic density functional theory (DFT). Only the complexes in which the peroxo ligands are coordinated to the uranyl moiety in a bidentate mode were considered. The calculated binding energies confirm that the affinity of the peroxo ligand for the uranyl group far exceeds that of the F(-), OH(-), CO3(2-), NO3(-), and H2O ligands. The formation of the monoperoxo complexes from UO2(H2O)5(2+) and HO2(-) were found to be exothermic in solution. In contrast, the formation of the monouranyl-diperoxo, UO2(O2)2X2(4-) or UO2(O2)2X(4-/3-) (where X is any of F(-), OH(-), CO3(2-), or NO3(-)), complexes were all found to be endothermic in aqueous solution. This suggests that the monoperoxo species are the terminal monouranyl peroxo complexes in solution, in agreement with recent experimental work. Overall, we find that the properties of the uranyl-peroxo complexes conform to well-known trends: the coordination of the peroxo ligand weakens the U-O(yl) bonds, stabilizes the σ(d) orbitals and causes a mixing between the uranyl π- and peroxo σ- and π-orbitals. The weakening of the U-O(yl) bonds upon peroxide coordination results in uranyl stretching vibrational frequencies that are much lower than those obtained after the coordination of carbonato or hydroxo ligands.

Biological Apatite Formed from Polyphosphate and Alkaline Phosphatase May Exchange Oxygen Isotopes from Water through Carbonate

NASA Astrophysics Data System (ADS)

Omelon, S. J.; Stanley, S. Y.; Gorelikov, I.; Matsuura, N.

2011-12-01

The oxygen isotopic composition in bone mineral phosphate is known to reflect the local water composition, environmental humidity, and diet1. Once ingested, biochemical processes presumably equilibrate PO43- with "body water" by the many biochemical reactions involving PO43- 2. Blake et al. demonstrated that enzymatic release of PO43- from organophosphorus compounds, and microbial metabolism of dissolved orthophosphate, significantly exchange the oxygen in precipitated apatite within environmental water3,4, which otherwise does not exchange with water at low temperatures. One of the enzymes that can cleave phosphates from organic substrates is alkaline phosphastase5, the enzyme also associated with bone mineralization. The literature often states that the mineral in bone in hydroxylapatite, however the mineral in bone is carbonated apatite that also contains some fluoride6. Deprotonation of HPO32- occurs at pH 12, which is impossibly high for biological system, and the predominate carbonate species in solution at neutral pH is HCO3-. To produce an apatite mineral without a significant hydroxyl content, it is possible that apatite biomineralization occurs through a polyphosphate pathway, where the oxygen atom required to transform polyphosphate into individual phosphate ions is from carbonate: [PO3-]n + CO32- -> [PO3-]n-1 + PO43- + CO2. Alkaline phosphatase can depolymerise polyphosphate into orthophosphate5. If alkaline phosphatase cleaves an oxygen atom from a calcium-carbonate complex, then there is no requirement for removing a hydrogen atom from the HCO3- or HPO43- ions of body water to form bioapatite. A mix of 1 mL of 1 M calcium polyphosphate hydogel, or nano-particles of calcium polyphosphate, and amorphous calcium carbonate were reacted with alkaline phosphatase, and maintained at neutral to basic pH. After two weeks, carbonated apatite and other calcium phosphate minerals were identified by powder x-ray diffraction. Orthophosphate and unreacted polyphosphate species were detected by Raman and IR spectroscopy. The oxygen isotope data of the reactants and products will also be presented. The possibility that carbonate acts as an intermediate reagent, transferring the oxygen from water to phosphate in biological apatite mineral formation may explain why biological apatite exhibits a significant carbonate content, and how this mineral is formed with an insignificant hydroxyl content. 1 Kohn, M.J., and Cerling, T.E. Rev Mineral Geochem 2002 (48) 455 2 Kolodny, Y., Luz, B., Navon, O. Earth Planet Sci Lett 1983 (64) 398 3 Blake, R.E., O'Neil, J.R., Garcia, G.A. Geochim et Cosmochim Acta 1997 (61) 4411 4 Blake, R.E., Alt, J.C., and Martini, A.M. PNAS 2001 (98) 2148-2153 5 Liang, Y., and Blake, R.E. Geochim Cosmochim Acta 2009 (73) 3782) 6 Pasteris, J.D. et al. Biomaterials 2004 (35) 229 7 Omelon et al., PLoS ONE 2009 4(5), e5634

Solid state and aqueous behavior of uranyl peroxide cage clusters

NASA Astrophysics Data System (ADS)

Pellegrini, Kristi Lynn

Uranyl peroxide cage clusters include a large family of more than 50 published clusters of a variety of sizes, which can incorporate various ligands including pyrophosphate and oxalate. Previous studies have reported that uranyl clusters can be used as a method to separate uranium from a solid matrix, with potential applications in reprocessing of irradiated nuclear fuel. Because of the potential applications of these novel structures in an advanced nuclear fuel cycle and their likely presence in areas of contamination, it is important to understand their behavior in both solid state and aqueous systems, including complex environments where other ions are present. In this thesis, I examine the aqueous behavior of U24Pp 12, as well as aqueous cluster systems with added mono-, di-, and trivalent cations. The resulting solutions were analyzed using dynamic light scattering and ultra-small angle X-ray scattering to evaluate the species in solution. Precipitates of these systems were analyzed using powder X-ray diffraction, X-ray fluorescence spectrometry, and Raman spectroscopy. The results of these analyses demonstrate the importance of cation size, charge, and concentration of added cations on the aqueous behavior of uranium macroions. Specifically, aggregates of various sizes and shapes form rapidly upon addition of cations, and in some cases these aggregates appear to precipitate into an X-ray amorphous material that still contains U24Pp12 clusters. In addition, I probe aggregation of U24Pp12 and U60, another uranyl peroxide cage cluster, in mixed solvent water-alcohol systems. The aggregation of uranyl clusters in water-alcohol systems is a result of hydrogen bonding with polar organic molecules and the reduction of the dielectric constant of the system. Studies of aggregation of uranyl clusters also allow for comparison between the newer uranyl polyoxometalate family and century-old transition metal polyoxometalates. To complement the solution studies of uranyl cage clusters, solid state analyses of U24Pp12 are presented, including single crystal X-ray diffraction and preliminary single crystal neutron diffraction. Solid state analyses are used to probe the complicated bonding environments between U24Pp12 and crystallized counterions, giving further insight into the importance of cluster protonation and counterions in uranyl cluster systems. The combination of solid state and solution techniques provides information about the complicated nature of uranyl peroxide nanoclusters, and insight towards future applications of clusters in the advanced nuclear fuel cycle and the environment.

[CIP and CAP fragments of parathormone and selected parameters of calcium-phosphate balance in patients with chronic kidney disease treated with repeated haemodialysis].

PubMed

Polak-Jonkisz, Dorota; Zwolińska, Danuta; Nahaczewska, Wiesława

2010-01-01

Chronic kidney disease (CKD) leads to bone and mineral complications, which are manifested, among others, by hyperparathyroidism, calcium-phosphate and vitamin D balance disturbances. The results of investigation assessing the usefulness of CAP/CIP ratio, (cyclase activating PTH/cyclase inactive PTH) as a marker of bone turnover and bone disturbances in this group of patients are contradictory. was to estimate the concentration of CAP and CIP of parathormone, connection with selected calcium-phosphate balance parameters and usefulness of CAP/CIP ratio to differentiate bone mineral density in patients with CKD treated with repeated haemodialysis. The study included 31 children aged 5 to 18 years. Group I - 15 haemodialysed children. Group II - 16 healthy children. The patients underwent the following serum measurements: calcium concentration (Ca), inorganic phosphate (P), 1.25-dihydroxyvitamin D, parathormone (intact PTH), and CAP, CIP were evaluated with Scantibodies Laboratory Inc test. In group I the densitometric examination was done using the Lunar DPX-L system, performing the overall bone measurement. In children from group I the average values of iPTH concentration and both CIP and CAP components were significantly elevated (p<0.05) as compared to group II. CAP/CIP ratio in group I was <1; in healthy children >1. Average concentrations of Ca and 1.25(OH)2D in serum of group I were lowered, although without statistical significance in comparison with group II. CAP/CIP ratio does not differentiate the children with bone disturbances. Densitometric examination revealed osteopenic changes in 3 children and osteoporosis in 2 children. There were no statistically significant correlations between the examined parameters. 1. The CIP/CAP ratio does not differentiate the bone mineral density status and it is not associated with biochemical parameters of calcium-phosphate metabolism. 2. This indicates its poor diagnostic utility with reference to mineralization disturbances in children with chronic kidney disease.

Post-depositional formation of vivianite-type minerals alters sediment phosphorus records

NASA Astrophysics Data System (ADS)

Dijkstra, Nikki; Hagens, Mathilde; Egger, Matthias; Slomp, Caroline P.

2018-02-01

Phosphorus (P) concentrations in sediments are frequently used to reconstruct past environmental conditions in freshwater and marine systems, with high values thought to be indicative of a high biological productivity. Recent studies suggest that the post-depositional formation of vivianite, an iron(II)-phosphate mineral, might significantly alter trends in P with sediment depth. To assess its importance, we investigate a sediment record from the Bornholm Basin that was retrieved during the Integrated Ocean Drilling Program (IODP) Baltic Sea Paleoenvironment Expedition 347 in 2013, consisting of lake sediments overlain by brackish-marine deposits. Combining bulk sediment geochemistry with microanalysis using scanning electron microscope energy dispersive spectroscopy (SEM-EDS) and synchrotron-based X-ray absorption spectroscopy (XAS), we demonstrate that vivianite-type minerals rich in manganese and magnesium are present in the lake deposits just below the transition to the brackish-marine sediments (at 11.5 to 12 m sediment depth). In this depth interval, phosphate that diffuses down from the organic-rich, brackish-marine sediments meets porewaters rich in dissolved iron in the lake sediments, resulting in the precipitation of iron(II) phosphate. Results from a reactive transport model suggest that the peak in iron(II) phosphate originally occurred at the lake-marine transition (9 to 10 m) and moved downwards due to changes in the depth of a sulfidization front. However, its current position relative to the lake-marine transition is stable as the vivianite-type minerals and active sulfidization fronts have been spatially separated over time. Experiments in which vivianite was subjected to sulfidic conditions demonstrate that incorporation of manganese or magnesium in vivianite does not affect its susceptibility to sulfide-induced dissolution. Our work highlights that post-depositional formation of iron(II) phosphates such as vivianite has the potential to strongly alter sedimentary P records particularly in systems that are subject to environmental perturbation, such as a change in primary productivity, which can be associated with a lake-marine transition.

Role of mineralization inhibitors in the regulation of hard tissue biomineralization: relevance to initial enamel formation and maturation

PubMed Central

Margolis, Henry C.; Kwak, Seo-Young; Yamazaki, Hajime

2014-01-01

Vertebrate mineralized tissues, i.e., enamel, dentin, cementum, and bone, have unique hierarchical structures and chemical compositions. Although these tissues are similarly comprised of a crystalline calcium apatite mineral phase and a protein component, they differ with respect to crystal size and shape, level and distribution of trace mineral ions, the nature of the proteins present, and their relative proportions of mineral and protein components. Despite apparent differences, mineralized tissues are similarly derived by highly concerted extracellular processes involving matrix proteins, proteases, and mineral ion fluxes that collectively regulate the nucleation, growth and organization of forming mineral crystals. Nature, however, provides multiple ways to control the onset, rate, location, and organization of mineral deposits in developing mineralized tissues. Although our knowledge is quite limited in some of these areas, recent evidence suggests that hard tissue formation is, in part, controlled through the regulation of specific molecules that inhibit the mineralization process. This paper addresses the role of mineralization inhibitors in the regulation of biological mineralization with emphasis on the relevance of current findings to the process of amelogenesis. Mineralization inhibitors can also serve to maintain driving forces for calcium phosphate precipitation and prevent unwanted mineralization. Recent evidence shows that native phosphorylated amelogenins have the capacity to prevent mineralization through the stabilization of an amorphous calcium phosphate precursor phase, as observed in vitro and in developing teeth. Based on present findings, the authors propose that the transformation of initially formed amorphous mineral deposits to enamel crystals is an active process associated with the enzymatic processing of amelogenins. Such processing may serve to control both initial enamel crystal formation and subsequent maturation. PMID:25309443

Absorption of Some Mineral Salts by Root System of Different Woody Species and Accumulation over a Whole Vegetative Cycle; ABSORPTION DE QUELQUES SELS PAR L'APPAREIL RADICULAIRE DE DIFFERENTES ESPECES LIGNEUSES ET ACCUMULATION AU COURS D'UN CYCLE VEGETATIF COMPLET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gagnaire, J.

1963-01-01

The concentration power of plant tissues and the translocation speed of mineral salts vary considerably with the absorbed salt, the botanical species, the considered tissue, and the part of the vegetative cycle. In Grenoble, with Picea excelsa, the true dormance is short and is accompanied by a pre-dormance period and a post dormance period. In the vegetative period, Picea excelsa leaves concentrate less mineral salt than Acer campestris leaves (coefficient 2 for Ca--3 for phosphates) and Populus nigra leaves (coefficient 3 for Ca, coefficient 5 for phosphates). Results of tracer studies are tabulated. (C.H.)

BRIDGER WILDERNESS AND GREEN-SWEETWATER ROADLESS AREA, WYOMING.

USGS Publications Warehouse

Worl, Ronald G.; Ryan, George S.

1984-01-01

A mineral-resource appraisal of the Bridger Wilderness and contiguous Green-Sweetwater Roadless Area in Wyoming was made. This rugged and remote region is mostly Precambrian crystalline granitic rocks that contain only small and discontinuous areas of mineralization. The area is considered to have little promise for metallic mineral deposits. Sedimentary rocks in the area have minor coal seams and beds of phosphate rock, but the coal beds are thin and of limited extent, and the phosphate rock is low-grade compared to similar rocks elsewhere in the region. A probable potential for oil and gas at depth, assigned to part of the area, is based on the assumption that oil- and gas-bearing rocks exist at depth below a low-angle thrust fault and a wedge of Precambrian crystalline rock.

Natural radionuclide concentrations in processed materials from Thai mineral industries.

PubMed

Chanyotha, S; Kranrod, C; Chankow, N; Kritsananuwat, R; Sriploy, P; Pangza, K

2012-11-01

The naturally occurring radioactive materials (NORMs) distributed in products, by-products and waste produced from Thai mineral industries were investigated. Samples were analysed for radioactivity concentrations of two principal NORM isotopes: (226)Ra and (228)Ra. The enrichment of NORM was found to occur during the treatment process of some minerals. The highest activity of (226)Ra (7 × 10(7) Bq kg(-1)) was in the scale from tantalum processing. The radium concentration in the discarded by-product material from metal ore dressing was also enriched by 3-10 times. Phosphogypsum, a waste produced from the production of phosphate fertilisers, contained 700 times the level of (226)Ra concentration found in phosphate ore. Hence, these residues were also sources of exposure to workers and the public, which needed to be controlled.

Impact of endocrine hyperfunction and phosphate wasting on bone in McCune-Albright syndrome.

PubMed

Lala, R; Matarazzo, P; Andreo, M; Defilippi, C; de Sanctis, C

2002-01-01

Skin dysplasia, as café-au-lait spots, bone fibrous dysplasia and peripheral endocrinopathies are the main clinical features of McCune-Albright syndrome (MAS). This illness is due to activating mutations of the Gsalpha protein and is spread with a mosaic pattern in affected tissues that consist of intermixed areas of normal and mutated cells. Peripheral endocrine secretion, free of hypothalamic pituitary control, is the hallmark of the endocrine syndromes: precocious puberty, Cushing's syndrome, hyperthyroidism and gigantism/acromegaly. In addition, phosphate wasting as hyperphosphaturia is often present. The impact of hormonal hypersecretion and phosphate loss on the bones of patients with MAS is poorly understood both in normal and fibrous bone tissue. As hypercortisolism and hyperthyroidism increase bone resorption, hyperestrogenism and growth hormone hypersecretion stimulate bone growth and mineralization, and phosphate wasting reduces bone mineral content. All these actions can be exerted at varying times and degrees in a single patient on lesional and non-lesional bones. Sonographic evidence of multiple diffused hyperechogenic spots in the testes of patients with MAS do not seem to be related to alterations in calcium-phosphate metabolism but rather to zonal dysplasia/hyperplasia of testicular tissue.

Recombinant DNA technology and click chemistry: a powerful combination for generating a hybrid elastin-like-statherin hydrogel to control calcium phosphate mineralization

PubMed Central

Misbah, Mohamed Hamed; Santos, Mercedes; Quintanilla, Luis; Günter, Christina; Alonso, Matilde; Taubert, Andreas

2017-01-01

Understanding the mechanisms responsible for generating different phases and morphologies of calcium phosphate by elastin-like recombinamers is supreme for bioengineering of advanced multifunctional materials. The generation of such multifunctional hybrid materials depends on the properties of their counterparts and the way in which they are assembled. The success of this assembly depends on the different approaches used, such as recombinant DNA technology and click chemistry. In the present work, an elastin-like recombinamer bearing lysine amino acids distributed along the recombinamer chain has been cross-linked via Huisgen [2 + 3] cycloaddition. The recombinamer contains the SNA15 peptide domains inspired by salivary statherin, a peptide epitope known to specifically bind to and nucleate calcium phosphate. The benefit of using click chemistry is that the hybrid elastin-like-statherin recombinamers cross-link without losing their fibrillar structure. Mineralization of the resulting hybrid elastin-like-statherin recombinamer hydrogels with calcium phosphate is described. Thus, two different hydroxyapatite morphologies (cauliflower- and plate-like) have been formed. Overall, this study shows that crosslinking elastin-like recombinamers leads to interesting matrix materials for the generation of calcium phosphate composites with potential applications as biomaterials. PMID:28487820

Effect of mineral phosphates on growth and nitrogen fixation of diazotrophic cyanobacteria Anabaena variabilis and Westiellopsis prolifica.

PubMed

Yandigeri, Mahesh S; Yadav, Arvind K; Meena, Kamlesh Kumar; Pabbi, Sunil

2010-03-01

The nitrogen fixing cyanobacterial strains namely Anabaena variabilis (Nostocales, Nostocaceae) and Westiellopsis prolifica (Nostocales, Hapalosiphonaceae) were evaluated for their nitrogen fixation and growth potential in response to different concentrations (10, 20 and 30 mg P) of the alternate insoluble P-sources Mussorie Rock Phosphate and Tricalcium Phosphate. Distinct and significant intergeneric differences were observed with respect to nitrogen fixation measured as Acetylene Reduction Activity (ARA) and growth potential as soluble proteins, total carbohydrate content, dry weight and total chlorophyll content in response to different concentrations of Mussorie Rock Phosphate and Tricalcium Phosphate. Both the strains showed higher soluble protein content at 20 mg P (Mussorie Rock Phosphate) that increased with time of incubation in A. variabilis. Both cyanobacteria recorded maximum Acetylene Reduction Activity at 20 mg P (Tricalcium Phosphate) followed by activity in presence of soluble phosphate (K2HPO4). The mean activity at all concentrations of insoluble phosphate (Mussorie Rock Phosphate and Tricalcium Phosphate) was more than in the presence of soluble phosphate.

Ultrastructure of sea urchin calcified tissues after high-pressure freezing and freeze substitution.

PubMed

Ameye, L; Hermann, R; Dubois, P

2000-08-01

The improvements brought by high-pressure freezing/freeze substitution fixation methods to the ultrastructural preservation of echinoderm mineralized tissues are investigated in developing pedicellariae and teeth of the echinoid Paracentrotus lividus. Three freeze substitution (FS) protocols were tested: one in the presence of osmium tetroxide, one in the presence of uranyl acetate, and the last in the presence of gallic acid. FS in the presence of osmium tetroxide significantly improved cell ultrastructure preservation and should especially be used for ultrastructural studies involving vesicles and the Golgi apparatus. With all protocols, multivesicular bodies, suggested to contain Ca(2+), were evident for the first time in skeleton-forming cells. FS in the presence of gallic acid allowed us to confirm the structured and insoluble character of a part of the organic matrix of mineralization in the calcification sites of the tooth, an observation which modifies the current understanding of biomineralization control in echinoderms. Copyright 2000 Academic Press.

URANIUM PURIFICATION PROCESS

DOEpatents

Winters, C.E.

1957-11-12

A method for the preparation of a diethyl ether solution of uranyl nitrate is described. Previously the preparation of such ether solutions has been difficult and expensive, since crystalline uranyl nitrate hexahydrate dissolves very slowly in ether. An improved method for effecting such dissolution has been found, and it comprises adding molten uranyl nitrate hexahydrate at a temperature of 65 to 105 deg C to the ether while maintaining the temperature of the ether solvent below its boiling point.

Synthesis, X-ray crystallography, thermal studies, spectroscopic and electrochemistry investigations of uranyl Schiff base complexes.

PubMed

Asadi, Zahra; Shorkaei, Mohammad Ranjkesh

2013-03-15

Some tetradentate salen type Schiff bases and their uranyl complexes were synthesized and characterized by UV-Vis, NMR, IR, TG, C.H.N. and X-ray crystallographic studies. From these investigations it is confirmed that a solvent molecule occupied the fifth position of the equatorial plane of the distorted pentagonal bipyramidal structure. Also, the kinetics of complex decomposition by using thermo gravimetric methods (TG) was studied. The thermal decomposition reactions are first order for the studied complexes. To examine the properties of uranyl complexes according to the substitutional groups, we have carried out the electrochemical studies. The electrochemical reactions of uranyl Schiff base complexes in acetonitrile were reversible. Copyright © 2012 Elsevier B.V. All rights reserved.

FY-15 Progress Report on Cleanup of irradiated SHINE Target Solutions Containing 140g-U/L Uranyl Sulfate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bennett, Megan E.; Bowers, Delbert L.; Vandegrift, George F.

2015-09-01

During FY 2012 and 2013, a process was developed to convert the SHINE Target Solution (STS) of irradiated uranyl sulfate (140 g U/L) to uranyl nitrate. This process is necessary so that the uranium solution can be processed by the UREX (Uranium Extraction) separation process, which will remove impurities from the uranium so that it can be recycled. The uranyl sulfate solution must contain <0.02 M SO 4 2- so that the uranium will be extractable into the UREXsolvent. In addition, it is desired that the barium content be below 0.0007 M, as this is the limit in the Resourcemore » Conservation and Recovery Act (RCRA).« less

Trace Uranium Partitioning in a Multiphase Nano-FeOOH System.

PubMed

McBriarty, Martin E; Soltis, Jennifer A; Kerisit, Sebastien; Qafoku, Odeta; Bowden, Mark E; Bylaska, Eric J; De Yoreo, James J; Ilton, Eugene S

2017-05-02

The characterization of trace elements in minerals using extended X-ray absorption fine structure (EXAFS) spectroscopy constitutes a first step toward understanding how impurities and contaminants interact with the host phase and the environment. However, limitations to EXAFS interpretation complicate the analysis of trace concentrations of impurities that are distributed across multiple phases in a heterogeneous system. Ab initio molecular dynamics (AIMD)-informed EXAFS analysis was employed to investigate the immobilization of trace uranium associated with nanophase iron (oxyhydr)oxides, a model system for the geochemical sequestration of radiotoxic actinides. The reductive transformation of ferrihydrite [Fe(OH) 3 ] to nanoparticulate iron oxyhydroxide minerals in the presence of uranyl (UO 2 ) 2+ (aq) resulted in the preferential incorporation of U into goethite (α-FeOOH) over lepidocrocite (γ-FeOOH), even though reaction conditions favored the formation of excess lepidocrocite. This unexpected result is supported by atomically resolved transmission electron microscopy. We demonstrate how AIMD-informed EXAFS analysis lifts the strict statistical limitations and uncertainty of traditional shell-by-shell EXAFS fitting, enabling the detailed characterization of the local bonding environment, charge compensation mechanisms, and oxidation states of polyvalent impurities in complex multiphase mineral systems.

Trace Uranium Partitioning in a Multiphase Nano-FeOOH System

DOE Office of Scientific and Technical Information (OSTI.GOV)

McBriarty, Martin E.; Soltis, Jennifer A.; Kerisit, Sebastien

The characterization of trace elements in minerals using extended X-ray absorption fine structure (EXAFS) spectroscopy constitutes a first step toward understanding how impurities and contaminants interact with the host phase and the environment. However, limitations to EXAFS interpretation complicate the analysis of trace concentrations of impurities that are distributed across multiple phases in a heterogeneous system. Ab initio molecular dynamics (AIMD)-informed EXAFS analysis was employed to investigate the immobilization of trace uranium associated with nanophase iron (oxyhydr)oxides, a model system for the geochemical sequestration of radiotoxic actinides. The reductive transformation of ferrihydrite [Fe(OH)3] to nanoparticulate iron oxyhydroxide minerals in themore » presence of uranyl (UO 2) 2+(aq) resulted in the preferential incorporation of U into goethite (α-FeOOH) over lepidocrocite (γ-FeOOH), even though reaction conditions favored the formation of excess lepidocrocite. This unexpected result is supported by atomically resolved transmission electron microscopy. We demonstrate how AIMD-informed EXAFS analysis lifts the strict statistical limitations and uncertainty of traditional shell-by-shell EXAFS fitting, enabling the detailed characterization of the local bonding environment, charge compensation mechanisms, and oxidation states of polyvalent impurities in complex multiphase mineral systems.« less

Phosphate Uptake-Independent Signaling Functions of the Type III Sodium-Dependent Phosphate Transporter, PiT-1, in Vascular Smooth Muscle Cells

PubMed Central

Chavkin, Nicholas W.; Jun Chia, Jia; Crouthamel, Matthew H.; Giachelli, Cecilia M.

2015-01-01

Vascular calcification (VC) is prevalent in chronic kidney disease and elevated serum inorganic phosphate (Pi) is a recognized risk factor. The type III sodium-dependent phosphate transporter, PiT-1, is required for elevated Pi-induced osteochondrogenic differentiation and matrix mineralization in vascular smooth muscle cells (VSMCs). However, the molecular mechanism(s) by which PiT-1 promotes these processes is unclear. In the present study, we confirmed that the Pi concentration required to induce osteochondrogenic differentiation and matrix mineralization of mouse VSMCs was well above that required for maximal Pi uptake, suggesting a signaling function of PiT-1 that was independent of Pi transport. Elevated Pi-induced signaling via ERK1/2 phosphorylation was abrogated in PiT-1 deficient VSMCs, but could be rescued by wild-type (WT) and a Pi transport-deficient PiT-1 mutant. Furthermore, both WT and transport-deficient PiT-1 mutants promoted osteochondrogenic differentiation as measured by decreased SM22α and increased osteopontin mRNA expression. Finally, compared to vector alone, expression of transport-deficient PiT-1 mutants promoted VSMC matrix mineralization, but not to the extent observed with PiT-1 WT. These data suggest that both Pi uptake-dependent and -independent functions of PiT-1 are important for VSMC processes mediating vascular calcification. PMID:25684711

The Role of Poly(Aspartic Acid) in the Precipitation of Calcium Phosphate in Confinement

PubMed Central

Cantaert, Bram; Beniash, Elia

2013-01-01

Many questions remain regarding the formation of ultrathin hydroxapatite (HAP) crystals within the confines of collagen fibrils of bones. These structures form through the interplay of the collagen matrix and non-collagenous proteins, and in vitro mineralization studies employing poly(aspartic acid) (PAsp) as a mimic of the non-collagenous proteins have generated mineralized fibrils with structures comparable to their biogenic counterparts. In this article, we employ the nanoscale cylindrical pores perforating track-etch filtration membranes to investigate the role of PAsp in controlling the infiltration and crystallization of calcium phosphate (CaP) within confined volumes. Oriented polycrystalline HAP and non-oriented octacalcium phosphate (OCP) rods precipitated within the membrane pores via an amorphous calcium phosphate (ACP) precursor, where PAsp increased the proportion of OCP rods. Further, ACP crystallized faster within the membranes than in bulk solution when PAsp was present, suggesting that PAsp inhibits crystallization in solution, but promotes it when bound to a substrate. Finally, in contrast to the collagen system, PAsp reduced the yield of intra-membrane mineral and failed to enhance infiltration. This suggests that a specific interaction between the collagen matrix and ACP/PAsp precursor particles drives effective infiltration. Thus, while orientation of HAP crystals can be achieved by confinement alone, the chemistry of the collagen matrix is necessary for efficient mineralisation with CaP. PMID:24409343

The Role of Poly(Aspartic Acid) in the Precipitation of Calcium Phosphate in Confinement.

PubMed

Cantaert, Bram; Beniash, Elia; Meldrum, Fiona C

2013-12-28

Many questions remain regarding the formation of ultrathin hydroxapatite (HAP) crystals within the confines of collagen fibrils of bones. These structures form through the interplay of the collagen matrix and non-collagenous proteins, and in vitro mineralization studies employing poly(aspartic acid) (PAsp) as a mimic of the non-collagenous proteins have generated mineralized fibrils with structures comparable to their biogenic counterparts. In this article, we employ the nanoscale cylindrical pores perforating track-etch filtration membranes to investigate the role of PAsp in controlling the infiltration and crystallization of calcium phosphate (CaP) within confined volumes. Oriented polycrystalline HAP and non-oriented octacalcium phosphate (OCP) rods precipitated within the membrane pores via an amorphous calcium phosphate (ACP) precursor, where PAsp increased the proportion of OCP rods. Further, ACP crystallized faster within the membranes than in bulk solution when PAsp was present, suggesting that PAsp inhibits crystallization in solution, but promotes it when bound to a substrate. Finally, in contrast to the collagen system, PAsp reduced the yield of intra-membrane mineral and failed to enhance infiltration. This suggests that a specific interaction between the collagen matrix and ACP/PAsp precursor particles drives effective infiltration. Thus, while orientation of HAP crystals can be achieved by confinement alone, the chemistry of the collagen matrix is necessary for efficient mineralisation with CaP.

Characterisation of Phosphate Accumulating Organisms and Techniques for Polyphosphate Detection: A Review

PubMed Central

Tarayre, Cédric; Nguyen, Huu-Thanh; Brognaux, Alison; Delepierre, Anissa; De Clercq, Lies; Charlier, Raphaëlle; Michels, Evi; Meers, Erik; Delvigne, Frank

2016-01-01

Phosphate minerals have long been used for the production of phosphorus-based chemicals used in many economic sectors. However, these resources are not renewable and the natural phosphate stocks are decreasing. In this context, the research of new phosphate sources has become necessary. Many types of wastes contain non-negligible phosphate concentrations, such as wastewater. In wastewater treatment plants, phosphorus is eliminated by physicochemical and/or biological techniques. In this latter case, a specific microbiota, phosphate accumulating organisms (PAOs), accumulates phosphate as polyphosphate. This molecule can be considered as an alternative phosphate source, and is directly extracted from wastewater generated by human activities. This review focuses on the techniques which can be applied to enrich and try to isolate these PAOs, and to detect the presence of polyphosphate in microbial cells. PMID:27258275

Template-assisted mineral formation via an amorphous liquid phase precursor route

NASA Astrophysics Data System (ADS)

Amos, Fairland F.

The search for alternative routes to synthesize inorganic materials has led to the biomimetic route of producing ceramics. In this method, materials are manufactured at ambient temperatures and in aqueous solutions with soluble additives and insoluble matrix, similar to the biological strategy for the formation of minerals by living organisms. Using this approach, an anionic polypeptide additive was used to induce an amorphous liquid-phase precursor to either calcium carbonate or calcium phosphate. This precursor was then templated on either organic or inorganic substrates. Non-equilibrium morphologies, such as two-dimensional calcium carbonate films, one-dimensional calcium carbonate mesostructures and "molten" calcium phosphate spherulites were produced, which are not typical of the traditional (additive-free) solution grown crystals in the laboratory. In the study of calcium carbonate, the amorphous calcium carbonate mineral formed via the liquid-phase precursor, either underwent a dissolution-recrystallization event or a pseudo-solid-state transformation to produce different morphologies and polymorphs of the mineral. Discrete or aggregate calcite crystals were formed via the dissolution of the amorphous phase to allow the reprecipitation of the stable crystal. Non-equilibrium morphologies, e.g., films, mesotubules and mesowires were templated using organic and inorganic substrates and compartments. These structures were generated via an amorphous solid to crystalline solid transformation. Single crystalline tablets and mesowires of aragonite, which are reported to be found only in nature as skeletal structures of marine organisms, such as mollusk nacre and echinoderm teeth, were successfully synthesized. These biomimetic structures were grown via the polymer-induced liquid-phase precursor route in the presence of magnesium. Only low magnesium-bearing calcite was formed in the absence of the polymer. A similar approach of using a polymeric additive was implemented in calcium phosphate. Spherulitic crystals and films, seemingly formed from a molten state, were produced. These structures served as nucleating surfaces for the radial formation of calcium oxalate minerals. The composite calcium phosphate-calcium oxalate assemblies are similar to the core-shell structures found in certain kidney stones.

Backfill composition for secondary barriers in nuclear waste repositories

DOEpatents

Beall, G.W.; Allard, B.M.

1980-05-30

A backfill composition for sorbing and retaining hazardous elements of nuclear wastes comprises 50 to 70% by weight of quartz, 10 to 30% by weight of montmorillonite, 1 to 10% by weight of phosphate mineral, 1 to 10% by weight of ferrous mineral, 1 to 10% by weight of sulfate mineral and 1 to 10% by weight of attapulgite.

Raman spectra of oriented and non-oriented Cu hydroxy-phosphate minerals: libethenite, cornetite, pseudomalachite, reichenbachite and ludjibaite.

PubMed

Kharbish, Sherif; Andráš, Peter; Luptáková, Jarmila; Milovská, Stanislava

2014-09-15

Oriented cornetite [Cu3PO4(OH)3], libethenite [Cu2PO4(OH)] and pseudomalachite [Cu5(PO4)2(OH)4] and non-oriented reichenbachite [Cu5(PO4)2(OH)4] and ludjibaite [Cu5(PO4)2(OH)4] minerals from Ľubietová and Špania Dolina dump fields, Banská Bystrica, Slovakia were examined by polarized Raman spectroscopy. The examined minerals display the characteristic vibrational modes of PO4 and OH groups and further lattice modes. The PO4 stretching and bending vibrations of the investigated minerals occur between 1150 and 900 cm(-1) and between 700 and 350 cm(-1), respectively. On the other hand, the hydroxyl group stretching and bending modes appear above 3350 cm(-1) and between 900 and 700 cm(-1), respectively. The lattice vibrations occur below 350 cm(-1). The different bond distances of the PO4 groups readily explain the shift of the bands to higher or lower wavenumbers among the studied Cu hydroxy-phosphate minerals. Copyright © 2014. Published by Elsevier B.V.

Acute Phosphate Restriction Leads to Impaired Fracture Healing and Resistance to BMP-2

PubMed Central

Wigner, Nathan A; Luderer, Hilary F; Cox, Megan K; Sooy, Karen; Gerstenfeld, Louis C; Demay, Marie B

2010-01-01

Hypophosphatemia leads to rickets and osteomalacia, the latter of which results in decreased biomechanical integrity of bones, accompanied by poor fracture healing. Impaired phosphate-dependent apoptosis of hypertrophic chondrocytes is the molecular basis for rickets. However, the underlying pathophysiology of impaired fracture healing has not been characterized previously. To address the role of phosphate in fracture repair, mice were placed on a phosphate-restricted diet 2 days prior to or 3 days after induction of a mid-diaphyseal femoral fracture to assess the effects of phosphate deficiency on the initial recruitment of mesenchymal stem cells and their subsequent differentiation. Histologic and micro-computed tomographic (µCT) analyses demonstrated that both phosphate restriction models dramatically impaired fracture healing primarily owing to a defect in differentiation along the chondrogenic lineage. Based on Sox9 and Sox5 mRNA levels, neither the initial recruitment of cells to the callus nor their lineage commitment was effected by hypophosphatemia. However, differentiation of these cells was impaired in association with impaired bone morphogenetic protein (BMP) signaling. In vivo ectopic bone-formation assays and in vitro investigations in ST2 stromal cells confirmed that phosphate restriction leads to BMP-2 resistance. Marrow ablation studies demonstrate that hypophosphatemia has different effects on injury-induced intramembranous bone formation compared with endochondral bone formation. Thus phosphate plays an important role in the skeleton that extends beyond mineralized matrix formation and growth plate maturation and is critical for endochondral bone repair. © 2010 American Society for Bone and Mineral Research. PMID:19839770

Mineral deposition in bacteria-filled and bacteria-free calcium bodies in the crustacean Hyloniscus riparius (Isopoda: Oniscidea).

PubMed

Vittori, Miloš; Rozman, Alenka; Grdadolnik, Jože; Novak, Urban; Štrus, Jasna

2013-01-01

Crustacean calcium bodies are epithelial sacs which contain a mineralized matrix. The objectives of this study were to describe the microscopic anatomy of calcium bodies in the terrestrial isopod Hyloniscus riparius and to establish whether they undergo molt-related structural changes. We performed 3D reconstruction of the calcium bodies from paraffin sections and analyzed their structure with light and electron microscopy. In addition, we analyzed the chemical composition of their mineralized matrices with micro-Raman spectroscopy. Two pairs of these organs are present in H. riparius. One pair is filled with bacteria while the other pair is not. In non-molting animals, the bacteria-filled calcium bodies contain apatite crystals and the bacteria-free calcium bodies enclose CaCO3-containing concretions with little organic matrix. During preparation for molt, an additional matrix layer is deposited in both pairs of calcium bodies. In the bacteria-filled calcium bodies it contains a mixture of calcium carbonate and calcium phosphate, whereas only calcium carbonate is present in bacteria-free calcium bodies. After ecdysis, all mineral components in bacteria-free calcium bodies and the additional matrix layer in bacteria-filled calcium bodies are completely resorbed. During calcium resorption, the apical surface of the calcium body epithelium is deeply folded and electron dense granules are present in spaces between epithelial cells. Our results indicate that the presence of bacteria might be linked to calcium phosphate mineralization. Calcium bodies likely provide a source of calcium and potentially phosphate for the mineralization of the new cuticle after molt. Unlike other terrestrial isopods, H. riparius does not form sternal CaCO3 deposits and the bacteria-free calcium bodies might functionally replace them in this species.

Assessing the ability to combine hyperspectral imaging (HSI) data with Mineral Liberation Analyzer (MLA) data to characterize phosphate rocks

NASA Astrophysics Data System (ADS)

Laakso, K.; Middleton, M.; Heinig, T.; Bärs, R.; Lintinen, P.

2018-07-01

Phosphorus (P) is fundamental to manufacturing fertilizers. Phosphorus is predominantly extracted from phosphate rocks which are a finite resource expected to potentially last only a few decades. To investigate the means of using the hyperspectral imaging (HSI) technology to detect the phosphate-bearing mineral apatite in carbonate mineral -rich rocks we analyzed hyperspectral laboratory imagery obtained in the visible-near infrared (VNIR; 400-1000 nm) and short-wave infrared (SWIR; 1000-2500 nm) wavelength regions. These data were analyzed using the Spectral Angle Mapper (SAM) and by focusing on the characteristic absorption features of the minerals. The potential of using the Mineral Liberation Analyzer (MLA) data to guide the HSI data analysis was explored. The results were validated by means of the electron probe microanalyzer (EPMA) and MLA data. The results suggest that the VNIR wavelength region is applicable to map the rare earth element -rich fluorapatite which is featureless in the SWIR wavelength range. As suggested by previous studies, data obtained in the SWIR wavelength region can be successfully used to distinguish the carbonate minerals calcite and dolomite. Despite the benefits of having MLA data to map the mineralogy of the samples, the ability to use these data suffered from the polishing of the rock samples after the HSI data were acquired. Also, the MLA data were only available from the rock surfaces from which the SWIR data were acquired, and thus its applicability to validate the results obtained in the VNIR wavelength region was limited. Despite the non-optimal data acquisition setup, the MLA data were useful in guiding the analysis of the HSI data, and in validating the results thus obtained.

Fourier Transformed Infra-Red Imaging of Femoral Neck Bone: Reduced Heterogeneity of Mineral-to-Matrix and Carbonate-to-Phosphate and more Variable Crystallinity in Treatment-Naïve Fracture Cases compared to Fracture-Free Controls

PubMed Central

Gourion-Arsiquaud, Samuel; Lukashova, Lyudmilla; Power, Jon; Loveridge, Nigel; Reeve, Jonathan; Boskey, Adele L.

2012-01-01

After age 60 hip fracture risk strongly increases, but only a fifth of this increase is attributable to reduced mineral density (BMD, measured clinically). Changes in bone quality, specifically bone composition as measured by Fourier Transform Infrared spectroscopic imaging (FTIRI), also contribute to fracture risk. Here, FTIRI was applied to study the femoral neck and provide spatially derived information on its mineral and matrix properties in age-matched fractured and non-fractured bones. Whole femoral neck cross sections, divided into quadrants along the neck’s axis, from 10 women with hip fracture and 10 cadaveric controls were studied using FTIRI and micro-computed Tomography. Although 3-dimensional micro-CT bone mineral densities were similar, the mineral-to-matrix ratio was reduced in the cases of hip fracture, confirming previous reports. New findings were that the FTIRI microscopic variation (heterogeneity) of the mineral-to-matrix ratio was substantially reduced in the fracture group as was the heterogeneity of the carbonate-to-phosphate ratio. Conversely, the heterogeneity of crystallinity was increased. Increased variation of crystallinity was statistically associated with reduced variation of the carbonate-to-phosphate ratio. Anatomical variation in these properties between the different femoral neck quadrants was reduced in the fracture group compared to controls. While our treatment-naïve patients had reduced rather than increased bending resistance, these changes in heterogeneity associated with hip fracture are in another way comparable to the effects of experimental bisphosphonate therapy, which decreases heterogeneity and other indicators of bone’s toughness as a material. PMID:22865771

Mineral Deposition in Bacteria-Filled and Bacteria-Free Calcium Bodies in the Crustacean Hyloniscus riparius (Isopoda: Oniscidea)

PubMed Central

Vittori, Miloš; Rozman, Alenka; Grdadolnik, Jože; Novak, Urban; Štrus, Jasna

2013-01-01

Crustacean calcium bodies are epithelial sacs which contain a mineralized matrix. The objectives of this study were to describe the microscopic anatomy of calcium bodies in the terrestrial isopod Hyloniscus riparius and to establish whether they undergo molt-related structural changes. We performed 3D reconstruction of the calcium bodies from paraffin sections and analyzed their structure with light and electron microscopy. In addition, we analyzed the chemical composition of their mineralized matrices with micro-Raman spectroscopy. Two pairs of these organs are present in H. riparius. One pair is filled with bacteria while the other pair is not. In non-molting animals, the bacteria-filled calcium bodies contain apatite crystals and the bacteria-free calcium bodies enclose CaCO3-containing concretions with little organic matrix. During preparation for molt, an additional matrix layer is deposited in both pairs of calcium bodies. In the bacteria-filled calcium bodies it contains a mixture of calcium carbonate and calcium phosphate, whereas only calcium carbonate is present in bacteria-free calcium bodies. After ecdysis, all mineral components in bacteria-free calcium bodies and the additional matrix layer in bacteria-filled calcium bodies are completely resorbed. During calcium resorption, the apical surface of the calcium body epithelium is deeply folded and electron dense granules are present in spaces between epithelial cells. Our results indicate that the presence of bacteria might be linked to calcium phosphate mineralization. Calcium bodies likely provide a source of calcium and potentially phosphate for the mineralization of the new cuticle after molt. Unlike other terrestrial isopods, H. riparius does not form sternal CaCO3 deposits and the bacteria-free calcium bodies might functionally replace them in this species. PMID:23554963

Effect of surface modification of nanofibres with glutamic acid peptide on calcium phosphate nucleation and osteogenic differentiation of marrow stromal cells.

PubMed

Karaman, Ozan; Kumar, Ankur; Moeinzadeh, Seyedsina; He, Xuezhong; Cui, Tong; Jabbari, Esmaiel

2016-02-01

Biomineralization is mediated by extracellular matrix (ECM) proteins with amino acid sequences rich in glutamic acid. The objective of this study was to investigate the effect of calcium phosphate deposition on aligned nanofibres surface-modified with a glutamic acid peptide on osteogenic differentiation of rat marrow stromal cells. Blend of EEGGC peptide (GLU) conjugated low molecular weight polylactide (PLA) and high molecular weight poly(lactide-co-glycolide) (PLGA) was electrospun to form aligned nanofibres (GLU-NF). The GLU-NF microsheets were incubated in a modified simulated body fluid for nucleation of calcium phosphate crystals on the fibre surface. To achieve a high calcium phosphate to fibre ratio, a layer-by-layer approach was used to improve diffusion of calcium and phosphate ions inside the microsheets. Based on dissipative particle dynamics simulation of PLGA/PLA-GLU fibres, > 80% of GLU peptide was localized to the fibre surface. Calcium phosphate to fibre ratios as high as 200%, between those of cancellous (160%) and cortical (310%) bone, was obtained with the layer-by-layer approach. The extent of osteogenic differentiation and mineralization of marrow stromal cells seeded on GLU-NF microsheets was directly related to the amount of calcium phosphate deposition on the fibres prior to cell seeding. Expression of osteogenic markers osteopontin, alkaline phosphatase (ALP), osteocalcin and type 1 collagen increased gradually with calcium phosphate deposition on GLU-NF microsheets. Results demonstrate that surface modification of aligned synthetic nanofibres with EEGGC peptide dramatically affects nucleation and growth of calcium phosphate crystals on the fibres leading to increased osteogenic differentiation of marrow stromal cells and mineralization. Copyright © 2013 John Wiley & Sons, Ltd.

Elevated Dietary Magnesium Prevents Connective Tissue Mineralization in a Mouse Model of Pseudoxanthoma Elasticum (Abcc6−/−)

PubMed Central

LaRusso, Jennifer; Li, Qiaoli; Jiang, Qiujie; Uitto, Jouni

2010-01-01

Pseudoxanthoma elasticum (PXE) is an autosomal recessive multi-system disorder characterized by ectopic connective tissue mineralization, with clinical manifestations primarily in the skin, eyes and the cardiovascular system. There is considerable, both intra-and inter-familial variability in the spectrum of phenotypic presentation. Previous studies have suggested that mineral content of the diet may modify the severity of the clinical phenotype in PXE. In this study, we utilized a targeted mutant mouse (Abcc6−/−) as a model system for PXE. We examined the effects of changes in dietary phosphate and magnesium on the mineralization process using calcification of the connective tissue capsule surrounding the vibrissae as an early phenotypic biomarker. Mice placed on custom-designed diets either high or low in phosphate did not show changes in mineralization, which was similar to that noted in Abcc6−/− mice on control diet. However, mice placed on diet enriched in magnesium (5-fold) showed no evidence of connective tissue mineralization in this mouse model of PXE. The inhibitory capacity of magnesium was confirmed in a cell-based mineralization assay system in vitro. Collectively, our observations suggest that assessment of dietary magnesium in patients with PXE may be warranted. PMID:19122649

Effects of copyrolysis of sludge with calcium carbonate and calcium hydrogen phosphate on chemical stability of carbon and release of toxic elements in the resultant biochars.

PubMed

Xu, Xuebin; Hu, Xin; Ding, Zhuhong; Chen, Yijun

2017-12-01

The potential release of toxic elements and the stability of carbon in sludge-based biochars are important on their application in soil remediation and wastewater treatment. In this study, municipal sludge was co-pyrolyzed with calcium carbonate (CaCO 3 ) and calcium dihydrogen phosphate [Ca(H 2 PO 4 ) 2 ] under 300 and 600 °C, respectively. The basic physicochemical properties of the resultant biochars were characterized and laboratory chemical oxidation and leaching experiments of toxic elements were conducted to evaluate the chemical stability of carbon in biochars and the potential release of toxic elements from biochars. Results show that the exogenous minerals changed the physico-chemical properties of the resultant biochars greatly. Biochars with exogenous minerals, especially Ca(H 2 PO 4 ) 2 , decreased the release of Zn, Cr, Ni, Cu, Pb, and As and the release ratios were less than 1%. Tessier's sequential extraction analysis revealed that labile toxic elements were transferred to residual fraction in the biochars with high pyrolysis temperature (600 °C) and exogenous minerals. Low risks for biochar-bound Pb, Zn, Cd, As, Cr, and Cu were confirmed according to risk assessment code (RAC) while the potential ecological risk index (PERI) revealed that the exogenous Ca(H 2 PO 4 ) 2 significantly decreased the risks from considerable to moderate level. Moreover, the exogenous minerals significantly increased the chemical stability of carbon in 600 °C-pyrolyzed biochars by 10-20%. These results indicated that the copyrolysis of sludge with phosphate and carbonate, especially phosphate, were effective methods to prepare the sludge-based biochars with immobilized toxic elements and enhanced chemical stability of carbon. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrolyte and mineral disturbances in septic acute kidney injury patients undergoing continuous renal replacement therapy

PubMed Central

Jung, Su-Young; Kim, Hyunwook; Park, Seohyun; Jhee, Jong Hyun; Yun, Hae-Ryong; Kim, Hyoungnae; Kee, Youn Kyung; Yoon, Chang-Yun; Oh, Hyung Jung; Chang, Tae Ik; Park, Jung Tak; Yoo, Tae-Hyun; Kang, Shin-Wook; Lee, Hajeong; Kim, Dong Ki; Han, Seung Hyeok

2016-01-01

Abstract Electrolyte and mineral disturbances remain a major concern in patients undergoing continuous renal replacement therapy (CRRT); however, it is not clear whether those imbalances are associated with adverse outcomes in patients with septic acute kidney injury (AKI) undergoing CRRT. We conducted a post-hoc analysis of data from a prospective randomized controlled trial. A total of 210 patients with a mean age of 62.2 years (136 [64.8%] males) in 2 hospitals were enrolled. Levels of sodium, potassium, calcium, and phosphate measured before (0 hour) and 24 hours after CRRT initiation. Before starting CRRT, at least 1 deficiency and excess in electrolytes or minerals were observed in 126 (60.0%) and 188 (67.6%) patients, respectively. The excess in these parameters was greatly improved, whereas hypokalemia and hypophosphatemia became more prevalent at 24 hours after CRRT. However, 1 and 2 or more deficiencies in those parameters at the 2 time points were not associated with mortality. However, during 28 days, 89 (71.2%) deaths occurred in patients with phosphate levels at 0 hour of ≥4.5 mg/dL as compared with 49 (57.6%) in patients with phosphate levels <4.5 mg/dL. The 90-day mortality was also significantly higher in patients with hyperphosphatemia. Similarly, in 184 patients who survived at 24 hours after CRRT, hyperphosphatemia conferred a 2.2-fold and 2.6-fold increased risk of 28- and 90-day mortality, respectively. The results remained unaltered when the serum phosphate level was analyzed as a continuous variable. Electrolyte and mineral disturbances are common, and hyperphosphatemia may predict poor prognosis in septic AKI patients undergoing CRRT. PMID:27603344

Kosnarite, KZr2(PO4)3, a new mineral from Mount Mica and Black Mountain, Oxford County, Maine

USGS Publications Warehouse

Brownfield, M.E.; Foord, E.E.; Sutley, S.J.; Botinelly, T.

1993-01-01

Kosnarite, ideally KZr2(PO4)3, has been identified as part of a late-stage, secondary phosphate mineral assemblage from the Mount Mica pegmatite at Paris, and from the Black Mountain pegmatite, Rumford, Oxford County, Maine. Kosnarite from Mount Mica occurs as pseudocubic rhombohedral crystals, as much as 0.9 mm in maximum dimension, that display the dominant {102} form. Color ranges from pale blue to blue-green to nearly colorless. The mineral has a white streak, is transparent, has a vitreous luster, and is nonfluorescent in ultraviolet light. It has a hardness of 4.5, is brittle with a conchoidal fracture, and has perfect {102} cleavage. Kosnarite from Black Mountain is almost pure KZr2(PO4)3 with only trace amounts of Hf, Mn, Na, and Rb. The mineral is one of three known alkali zirconium phosphates; the others are gainesite and the Cs analogue of gainesite. -from Author

Use of ferric-impregnated volcanic ash for arsenate (V) adsorption from contaminated water with various mineralization degrees.

PubMed

Chen, Rongzhi; Zhang, Zhenya; Yang, Yingnan; Lei, Zhongfang; Chen, Nan; Guo, Xu; Zhao, Chao; Sugiura, Norio

2011-01-15

Ferric-impregnated volcanic ash (FVA) which consisted mainly of different forms of iron and aluminum oxide minerals was developed for arsenate (V) removal from an aqueous medium. The adsorption experiments were conducted in both DI water samples and actual water (Lake Kasumigaura, Japan) to investigate the effects of solution mineralization degree on the As(V) removal. Kinetic and equilibrium studies conducted in actual water revealed that the mineralization of water greatly elevated the As(V) adsorption on FVA. The experiment performed in DI water indicated that the existence of multivalence metallic cations significantly enhanced the As(V) adsorption ability, whereas competing anions such as fluoride and phosphate greatly decreased the As(V) adsorption. It is suggested that FVA is a cost-effective adsorbent for As(V) removal in low-level phosphate and fluoride solution. It was important to conduct the batch experiment using the actual water to investigate the arsenic removal on adsorbents. Copyright © 2010 Elsevier Inc. All rights reserved.

Uranyl adsorption kinetics within silica gel: dependence on flow velocity and concentration

NASA Astrophysics Data System (ADS)

Dodd, Brandon M.; Tepper, Gary

2017-09-01

Trace quantities of a uranyl dissolved in water were measured using a simple optical method. A dilute solution of uranium nitrate dissolved in water was forced through nanoporous silica gel at fixed and controlled water flow rates. The uranyl ions deposited and accumulated within the silica gel and the uranyl fluorescence within the silica gel was monitored as a function of time using a light emitting diode as the excitation source and a photomultiplier tube detector. It was shown that the response time of the fluorescence output signal at a particular volumetric flow rate or average liquid velocity through the silica gel can be used to quantify the concentration of uranium in water. The response time as a function of concentration decreased with increasing flow velocity.

The Phosphates of Pleistocene-Holocene Sediments of the Eastern Gallery of Denisova Cave

NASA Astrophysics Data System (ADS)

Shunkov, M. V.; Kulik, N. A.; Kozlikin, M. B.; Sokol, E. V.; Miroshnichenko, L. V.; Ulianov, V. A.

2018-01-01

Authigenic phosphate mineralization was first studied on the territory of Russia on the basis of the Holocene and Pleistocene deposits of Denisova Cave. The formation of phosphates in the eastern gallery is related to biodegradation of the horizons of guano of insectivorous bats, which inhabited the cave in the absence man. The results confirmed the archaeological record of the Holocene and the upper part of Pleistocene sequences of the eastern gallery.

Fabrication and characterization of poly(DL-lactic-co-glycolic acid)/zirconia-hybridized amorphous calcium phosphate composites

PubMed Central

WHITED, BRYCE M.; GOLDSTEIN, AARON S.; SKRTIC, DRAGO; LOVE, BRIAN J.

2010-01-01

Several minerals, such as hydroxyapatite and β-tricalcium phosphate, have been incorporated into bioresorbable polyester bone scaffolds to increase the osteoconductivity both in vitro and in vivo. More soluble forms of calcium phosphate that release calcium and phosphate ions have been postulated as factors that increase osteoblast differentiation and mineralization. Recently, a zirconia-hybridized pyrophosphate-stabilized amorphous calcium phosphate (Zr-ACP) has been synthesized allowing controlled release of calcium and phosphate ions. When incorporated into bioresorbable scaffolds, Zr-ACP has the potential to induce osteoconductivity. In this study, 80–90% (w/v) porous poly(DL-LActic-co-glycolic acid) (PLGA) scaffolds were formed by thermal phase separation from dioxane while incorporating Zr-ACP. Scanning electron microscopy revealed a highly porous structure with a pore size ranging from a few μm to about 100 μm, smaller than we had hoped for. Zr-ACP particles were evenly dispersed in the composite structure and incorporated into the pore walls. The amorphous structure of the Zr-ACP was maintained during composite fabrication, as found by X-ray diffraction. Composite scaffolds had larger compressive yield strengths and moduli compared to pure polymer scaffolds. These initial efforts demonstrate that PLGA/Zr-ACP composites can be formed in ways that ultimately serve as promising bone scaffolds in tissue engineering. PMID:16768292

Polyaspartic Acid Concentration Controls the Rate of Calcium Phosphate Nanorod Formation in High Concentration Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krogstad, Daniel V.; Wang, Dongbo; Lin-Gibson, Sheng

Polyelectrolytes are known to greatly affect calcium phosphate (CaP) mineralization. The reaction kinetics as well as the CaP phase, morphology and aggregation state depend on the relative concentrations of the polyelectrolyte and the inorganic ions in a complex, nonlinear manner. This study examines the structural evolution and kinetics of polyaspartic acid (pAsp) directed CaP mineralization at high concentrations of polyelectrolytes, calcium, and total phosphate (19–30 mg/mL pAsp, 50–100 mM Ca2+, Ca/P = 2). Using a novel combination of characterization techniques including cryogenic transmission electron microscopy (cryo-TEM), spectrophotometry, X-ray total scattering pair distribution function analysis, and attenuated total reflectance Fourier transformmore » infrared spectroscopy (ATR-FTIR), it was determined that the CaP mineralization occurred over four transition steps. The steps include the formation of aggregates of pAsp stabilized CaP spherical nanoparticles (sNP), crystallization of sNP, oriented attachment of the sNP into nanorods, and further crystallization of the nanorods. The intermediate aggregate sizes and the reaction kinetics were found to be highly polymer concentration dependent while the sizes of the particles were not concentration dependent. This study demonstrates the complex role of pAsp in controlling the mechanism as well as the kinetics of CaP mineralization.« less

A new synthetic granular calcium phosphate compound induces new bone in a sinus lift rabbit model.

PubMed

Trbakovic, Amela; Hedenqvist, Patricia; Mellgren, Torbjörn; Ley, Cecilia; Hilborn, Jöns; Ossipov, Dmitri; Ekman, Stina; Johansson, Carina B; Jensen-Waern, Marianne; Thor, Andreas

2018-03-01

The aim of this study was to investigate if a synthetic granular calcium phosphate compound (CPC) and a composite bisphosphonate-linked hyaluronic acid-calcium phosphate hydrogel (HABP·CaP) induced similar or more amount of bone as bovine mineral in a modified sinus lift rabbit model. Eighteen adult male New Zeeland White rabbits, received randomly one of the two test materials on a random side of the face, and bovine mineral as control on the contralateral side. In a sinus lift, the sinus mucosa was elevated and a titanium mini-implant was placed in the alveolar bone. Augmentation material (CPC, HABP·CaP or bovine bone) was applied in the space around the implant. The rabbits were euthanized three months after surgery and qualitative and histomorphometric evaluation were conducted. Histomorphometric evaluation included three different regions of interest (ROIs) and the bone to implant contact on each installed implant. Qualitative assessment (p = <.05), histomorphometric evaluations (p = < .01), and implant incorporation (p = <.05) showed that CPC and bovine mineral induced similar amount of bone and more than the HABP·CaP hydrogel. CPC induced similar amount of bone as bovine mineral and both materials induced more bone than HABP·CaP hydrogel. The CPC is suggested as a synthetic alternative for augmentations in the maxillofacial area. Copyright © 2017 Elsevier Ltd. All rights reserved.

Uranium Biomineralization By Natural Microbial Phosphatase Activities in the Subsurface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taillefert, Martial

This project investigated the geochemical and microbial processes associated with the biomineralization of radionuclides in subsurface soils. During this study, it was determined that microbial communities from the Oak Ridge Field Research subsurface are able to express phosphatase activities that hydrolyze exogenous organophosphate compounds and result in the non-reductive bioimmobilization of U(VI) phosphate minerals in both aerobic and anaerobic conditions. The changes of the microbial community structure associated with the biomineralization of U(VI) was determined to identify the main organisms involved in the biomineralization process, and the complete genome of two isolates was sequenced. In addition, it was determined thatmore » both phytate, the main source of natural organophosphate compounds in natural environments, and polyphosphate accumulated in cells could also be hydrolyzed by native microbial population to liberate enough orthophosphate and precipitate uranium phosphate minerals. Finally, the minerals produced during this process are stable in low pH conditions or environments where the production of dissolved inorganic carbon is moderate. These findings suggest that the biomineralization of U(VI) phosphate minerals is an attractive bioremediation strategy to uranium bioreduction in low pH uranium-contaminated environments. These efforts support the goals of the SBR long-term performance measure by providing key information on "biological processes influencing the form and mobility of DOE contaminants in the subsurface".« less

[Effects of nandrolone decanoate on bone mineral content and intestinal absorption of calcium].

PubMed

Nuti, R; Righi, G A; Turchetti, V; Vattimo, A

1984-01-28

To evaluate the effects of a long-term treatment with nandrolone decanoate on metabolism of the skeleton, a double-blind randomized study was carried out in women with joint diseases without metabolic bone derangement. Ten patients were treated with 50 mg of nandrolone decanoate every three weeks for two years; in six subjects a treatment with placebo was performed. As it concerns plasma calcium and phosphate, serum alkaline phosphatase, urinary excretion of calcium, phosphate, hydroxyproline and cAMP, as parathyroid index, it was not observed significant differences in the two examined groups. While in placebo group at the end of the study the intestinal radiocalcium remained unchanged and bone mineral content showed a slight decrease, on the contrary nandrolone decanoate treatment promoted a significant improvement in intestinal calcium absorption and an increase in bone mineral content.

An artificially constructed Syngonium podophyllum-Aspergillus niger combinate system for removal of uranium from wastewater.

PubMed

He, Jia-dong; Wang, Yong-dong; Hu, Nan; Ding, Dexin; Sun, Jing; Deng, Qin-wen; Li, Chang-wu; Xu, Fei

2015-12-01

Aspergillus niger was inoculated to the roots of five plants, and the Syngonium podophyllum-A. niger combinate system (SPANCS) was found to be the most effective in removing uranium from hydroponic liquid with initial uranium concentration of 5 mg L(-1). Furthermore, the hydroponic experiments on the removal of uranium from the hydroponic liquids with initial uranium concentrations of 0.5, 1.0, and 3.0 mg L(-1) by the SPANCS were conducted, the inhibitory effect of A. niger on the growth of S. podophyllum in the SPANCS was studied, the accumulation characteristics of uranium by S. podophyllum in the SPANCS were analyzed, and the Fourier transform infrared (FT-IR) and extended X-ray absorption fine structure (EXAFS) spectra were measured. The results show that the removal of uranium by the SPANCS from the hydroponic liquids with initial uranium concentrations of 0.5, 1.0, and 3.0 mg L(-1) reached 98.20, 97.90, and 98.50%, respectively, after 37 days of accumulation of uranium; that the uranium concentrations in the hydroponic liquids decreased to 0.009, 0.021, and 0.045 mg L(-1), respectively, which are lower than the stipulated concentration for discharge of 0.050 mg L(-1) by the People's Republic of China; that A. niger helped to generate more groups in the root of S. podophyllum which can improve the complexing capability of S. podophyllum for uranium; and that the uranium accumulated in the root of S. podophyllum was in the form of phosphate uranyl and carboxylic uranyl.

Injectable TEMPO-oxidized nanofibrillated cellulose/biphasic calcium phosphate hydrogel for bone regeneration.

PubMed

Safwat, Engie; Hassan, Mohammad L; Saniour, Sayed; Zaki, Dalia Yehia; Eldeftar, Mervat; Saba, Dalia; Zazou, Mohamed

2018-05-01

Nanofibrillated cellulose, obtained from rice straw agricultural wastes was used as a substrate for the preparation of a new injectable and mineralized hydrogel for bone regeneration. Tetramethyl pyridine oxyl (TEMPO) oxidized nanofibrillated cellulose, was mineralized through the incorporation of a prepared and characterized biphasic calcium phosphate at a fixed ratio of 50 wt%. The TEMPO-oxidized rice straw nanofibrillated cellulose was characterized using transmission electron microscopy, Fourier transform infrared, and carboxylic content determination. The injectability and viscosity of the prepared hydrogel were evaluated using universal testing machine and rheometer testing, respectively. Cytotoxicity and alkaline phosphatase level tests on osteoblast like-cells for in vitro assessment of the biocompatibility were investigated. Results revealed that the isolated rice straw nanofibrillated cellulose is a nanocomposite of the cellulose nanofibers and silica nanoparticles. Rheological properties of the tested materials are suitable for use as injectable material and of nontoxic effect on osteoblast-like cells, as revealed by the positive alkaline phosphate assay. However, nanofibrillated cellulose/ biphasic calcium phosphate hydrogel showed higher cytotoxicity and lower bioactivity test results when compared to that of nanofibrillated cellulose.

PREPARATION OF URANIUM TRIOXIDE

DOEpatents

Buckingham, J.S.

1959-09-01

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

ELECTROLYTIC PRODUCTION OF URANIUM TETRAFLUORIDE

DOEpatents

Lofthouse, E.

1954-08-31

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

Sorption of uranyl ions from various acido systems by amphoteric epoxy amine ion-exchange resins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rychkov, V.N.; Radionov, B.K.; Molochnikov, L.S.

1995-03-01

Sorption of uranyl ions by epoxy amine ampholytes with N-monomethylenephosphonic acid groups modified with pyridine or quaternary ammonium groups was studied under dynamic conditions. Heterocyclic nitrogen favors sorption of uranyl ion from fluoride, sulfate, and fluoride-sulfate solutions. The ESR studies of mono- and bimetallic forms of nitrogen-containing ampholytes with copper(II) as paramagnetic marker revealed the characteristics of uranium(VI) interaction with cation- and anion-exchange groups and its dependence on the fluoride content in solution.

MIH supplementation strategies: prospective clinical and laboratory trial.

PubMed

Baroni, C; Marchionni, S

2011-03-01

The use of calcium-phosphate casein on hypomineralized molars (molar incisor hypomineralization, MIH) has been proposed but not clinically investigated. Qualitative and quantitative effects of supplementation with a calcium-phosphate casein product on MIH molars were monitored over a period of three years. Molar replicas, minimally invasive biopsies and their SEM microphotographs, plus ESEM/EDX semi-quantitative peaks of elements present in affected enamel were evaluated. Mineralization, morphology, and porosity appeared markedly improved, with calcium and phosphate levels reaching almost normal levels at three years' follow-up. The hypothesis tested was rejected, since calcium-phosphate casein improved enamel morphology in vivo.

Electrospinning of calcium phosphate-poly (d,l-lactic acid) nanofibers for sustained release of water-soluble drug and fast mineralization

PubMed Central

Fu, Qi-Wei; Zi, Yun-Peng; Xu, Wei; Zhou, Rong; Cai, Zhu-Yun; Zheng, Wei-Jie; Chen, Feng; Qian, Qi-Rong

2016-01-01

Calcium phosphate-based biomaterials have been well studied in biomedical fields due to their outstanding chemical and biological properties which are similar to the inorganic constituents in bone tissue. In this study, amorphous calcium phosphate (ACP) nanoparticles were prepared by a precipitation method, and used for preparation of ACP-poly(d,l-lactic acid) (ACP-PLA) nanofibers and water-soluble drug-containing ACP-PLA nanofibers by electrospinning. Promoting the encapsulation efficiency of water-soluble drugs in electrospun hydrophobic polymer nanofibers is a common problem due to the incompatibility between the water-soluble drug molecules and hydrophobic polymers solution. Herein, we used a native biomolecule of lecithin as a biocompatible surfactant to overcome this problem, and successfully prepared water-soluble drug-containing ACP-PLA nanofibers. The lecithin and ACP nanoparticles played important roles in stabilizing water-soluble drug in the electrospinning composite solution. The electrospun drug-containing ACP-PLA nanofibers exhibited fast mineralization in simulated body fluid. The ACP nanoparticles played the key role of seeds in the process of mineralization. Furthermore, the drug-containing ACP-PLA nanofibers exhibited sustained drug release which simultaneously occurred with the in situ mineralization in simulated body fluid. The osteoblast-like (MG63) cells with spreading filopodia were well observed on the as-prepared nanofibrous mats after culturing for 24 hours, indicating a high cytocompatibility. Due to the high biocompatibility, sustained drug release, and fast mineralization, the as-prepared composite nanofibers may have potential applications in water-soluble drug loading and release for tissue engineering. PMID:27785016

Modulating Uranium Binding Affinity in Engineered Calmodulin EF-Hand Peptides: Effect of Phosphorylation

PubMed Central

Pardoux, Romain; Sauge-Merle, Sandrine; Lemaire, David; Delangle, Pascale; Guilloreau, Luc; Adriano, Jean-Marc; Berthomieu, Catherine

2012-01-01

To improve our understanding of uranium toxicity, the determinants of uranyl affinity in proteins must be better characterized. In this work, we analyzed the contribution of a phosphoryl group on uranium binding affinity in a protein binding site, using the site 1 EF-hand motif of calmodulin. The recombinant domain 1 of calmodulin from A. thaliana was engineered to impair metal binding at site 2 and was used as a structured template. Threonine at position 9 of the loop was phosphorylated in vitro, using the recombinant catalytic subunit of protein kinase CK2. Hence, the T9TKE12 sequence was substituted by the CK2 recognition sequence TAAE. A tyrosine was introduced at position 7, so that uranyl and calcium binding affinities could be determined by following tyrosine fluorescence. Phosphorylation was characterized by ESI-MS spectrometry, and the phosphorylated peptide was purified to homogeneity using ion-exchange chromatography. The binding constants for uranyl were determined by competition experiments with iminodiacetate. At pH 6, phosphorylation increased the affinity for uranyl by a factor of ∼5, from Kd = 25±6 nM to Kd = 5±1 nM. The phosphorylated peptide exhibited a much larger affinity at pH 7, with a dissociation constant in the subnanomolar range (Kd = 0.25±0.06 nM). FTIR analyses showed that the phosphothreonine side chain is partly protonated at pH 6, while it is fully deprotonated at pH 7. Moreover, formation of the uranyl-peptide complex at pH 7 resulted in significant frequency shifts of the νas(P-O) and νs(P-O) IR modes of phosphothreonine, supporting its direct interaction with uranyl. Accordingly, a bathochromic shift in νas(UO2)2+ vibration (from 923 cm−1 to 908 cm−1) was observed upon uranyl coordination to the phosphorylated peptide. Together, our data demonstrate that the phosphoryl group plays a determining role in uranyl binding affinity to proteins at physiological pH. PMID:22870263

Uranyl nitrate-exposed rat alveolar macrophages cell death: Influence of superoxide anion and TNF α mediators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orona, N.S.; Tasat, D.R., E-mail: deborah.tasat@unsam.edu.ar; School of Dentistry, University of Buenos Aires, M. T. de Alvear 2142

2012-06-15

Uranium compounds are widely used in the nuclear fuel cycle, military and many other diverse industrial processes. Health risks associated with uranium exposure include nephrotoxicity, cancer, respiratory, and immune disorders. Macrophages present in body tissues are the main cell type involved in the internalization of uranium particles. To better understand the pathological effects associated with depleted uranium (DU) inhalation, we examined the metabolic activity, phagocytosis, genotoxicity and inflammation on DU-exposed rat alveolar macrophages (12.5–200 μM). Stability and dissolution of DU could differ depending on the dissolvent and in turn alter its biological action. We dissolved DU in sodium bicarbonate (NaHCO{submore » 3} 100 mM) and in what we consider a more physiological vehicle resembling human internal media: sodium chloride (NaCl 0.9%). We demonstrate that uranyl nitrate in NaCl solubilizes, enters the cell, and elicits its cytotoxic effect similarly to when it is diluted in NaHCO{sub 3}. We show that irrespective of the dissolvent employed, uranyl nitrate impairs cell metabolism, and at low doses induces both phagocytosis and generation of superoxide anion (O{sub 2}{sup −}). At high doses it provokes the secretion of TNFα and through all the range of doses tested, apoptosis. We herein suggest that at DU low doses O{sub 2}{sup −} may act as the principal mediator of DNA damage while at higher doses the signaling pathway mediated by O{sub 2}{sup −} may be blocked, prevailing damage to DNA by the TNFα route. The study of macrophage functions after uranyl nitrate treatment could provide insights into the pathophysiology of uranium‐related diseases. -- Highlights: ► Uranyl nitrate effect on cultured macrophages is linked to the doses and independent of its solubility. ► At low doses uranyl nitrate induces generation of superoxide anion. ► At high doses uranyl nitrate provokes secretion of TNFα. ► Uranyl nitrate induces apoptosis through all the range of doses tested.« less

Vehicle influence on permeation through intact and compromised skin.

PubMed

Gujjar, Meera; Banga, Ajay K

2014-09-10

The purpose of this study was to compare the transdermal permeation of a model compound, diclofenac diethylamine, from a hydrophilic and lipophilic vehicle across in vitro models simulating compromised skin. Mineral oil served as a lipophilic vehicle while 10mM phosphate buffered saline served as a hydrophilic vehicle. Compromised skin was simulated by tape stripping, delipidization, or microneedle application and compared with intact skin as a control. Transepidermal water loss was measured to assess barrier function. Skin compromised with tape stripping and delipidization significantly (p<0.05) increased permeation of diclofenac diethylamine compared to intact and microneedle treated skin with phosphate buffered saline vehicle. A similar trend in permeation was observed with mineral oil as the vehicle. For both vehicles, permeation across skin increased in the same order and correlated with degree of barrier impairment as indicated by transepidermal water loss values: intact

Gypsum, jarosite, and hydrous iron-phosphate in Martian meteorite Roberts Massif 04262: Implications for sulfate geochemistry on Mars.

NASA Astrophysics Data System (ADS)

Greenwood, J. P.

2008-12-01

Gypsum has been identified on Mars by MEX OMEGA [1] and jarosite identified via MER-B lander [2] and both minerals are examples of the importance of calcium and iron sulfates in Martian weathering processes. The weathering of Martian basalt to form Ca and iron sulfates should be an important process on Mars. Martian jarosite has been identified in MIL 03346 [3] and Ca-sulfate has been identified in EETA 79001 [4], but both phases have yet to be identified in the same Martian sample. In Roberts Massif 04262, an olivine-phyric shergottite, iron-sulfide and calcium-phosphate minerals are undergoing reaction (dissolution and reprecipitation?) to form gypsum, jarosite, and an iron-phosphate phase, presumably during the meteorite's residence in Antarctica. If true, then an acidic and oxidizing fluid was present in this meteorite, due to the formation of jarosite which requires fluid of this type to form [5]. The weathering of iron-sulfides on Earth to form acidic and oxidizing fluids is common, thus this can be reconciled with the formation of an acidic fluid in a basic rock. Presumably, under more extensive weathering of silicate minerals in Martian basalt, the pH would be raised to values where jarosite would not be stable. While the weathering of RBT 04262 is likely occurring in Antarctica, a similar susceptibility of the apatite and pyrrhotite to incipient weathering on Mars may be expected. Oxidizing crustal fluids on Mars may attack iron- sulfides first in Martian basalts. The weathering of iron-sulfides leads to increasing acidity of fluids, which would enhance the dissolution of the calcium-phosphate minerals [6]. The formation of jarosite, gypsum, and iron-phosphate minerals during the early stages of weathering of Martian basalts may be an important process on Mars globally. [1] Gendrin, A. et al. (2005) Science, 307, 1587-1591. [2] Klingelhöfer et al. (2004) Science, 306, 1740- 1745. [3] Vicenzi E. P. et al. (2007) LPSC XXXVIII, Abstract 2335. [4] Gooding J. L. et al. (1988) GCA, 52, 909-915. [5] Greenwood J. P. et al. (2005) LPSC XXXVI, Abstract 2348. [6] Greenwood J. P. and Blake R. E. (2006) Geology, 34, 953-956.

NELL-1 increases pre-osteoblast mineralization using both phosphate transporter Pit1 and Pit2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cowan, Catherine M.; Dental and Craniofacial Research Institute and Section of Orthodontics, School of Dentistry, University of California, Los Angeles, 40833 Le Conte Ave, Los Angeles, CA 90095; Zhang, Xinli

2012-06-08

Highlights: Black-Right-Pointing-Pointer NELL-1 accelerates extracellular matrix mineralization in MC3T3-E1 pre-osteoblasts. Black-Right-Pointing-Pointer NELL-1 significantly increases intracellular inorganic phosphate levels. Black-Right-Pointing-Pointer NELL-1 positively regulates osteogenesis but not proliferation in MC3T3-E1 cells. Black-Right-Pointing-Pointer NELL-1 regulates inorganic phosphate transporter activity. -- Abstract: NELL-1 is a potent osteoinductive molecule that enhances bone formation in multiple animal models through currently unidentified pathways. In the present manuscript, we hypothesized that NELL-1 may regulate osteogenic differentiation accompanied by alteration of inorganic phosphate (Pi) entry into the osteoblast via sodium dependent phosphate (NaPi) transporters. To determine this, MC3T3-E1 pre-osteoblasts were cultured in the presence of recombinant human (rh)NELL-1 ormore » rhBMP-2. Analysis was performed for intracellular Pi levels through malachite green staining, Pit-1 and Pit-2 expression, and forced upregulation of Pit-1 and Pit-2. Results showed rhNELL-1 to increase MC3T3-E1 matrix mineralization and Pi influx associated with activation of both Pit-1 and Pit-2 channels, with significantly increased Pit-2 production. In contrast, Pi transport elicited by rhBMP-2 showed to be associated with increased Pit-1 production only. Next, neutralizing antibodies against Pit-1 and Pit-2 completely abrogated the Pi influx effect of rhNELL-1, suggesting rhNELL-1 is dependent on both transporters. These results identify one potential mechanism of action for rhNELL-1 induced osteogenesis and highlight a fundamental difference between NELL-1 and BMP-2 signaling.« less

The molecular structure of the phosphate mineral chalcosiderite - A vibrational spectroscopic study

NASA Astrophysics Data System (ADS)

Frost, Ray L.; Xi, Yunfei; Scholz, Ricardo; Ribeiro, Carlos Augusto de Brito

2013-07-01

The mineral chalcosiderite with formula CuFe6(PO4)4(OH)8ṡ4H2O has been studied by Raman spectroscopy and by infrared spectroscopy. A comparison of the chalcosiderite spectra is made with the spectra of turquoise. The spectra of the mineral samples are very similar in the 1200-900 cm-1 region but strong differences are observed in the 900-100 cm-1 region. The effect of substitution of Fe for Al in chalcosiderite shifts the bands to lower wavenumbers. Factor group analysis (FGA) implies four OH stretching vibrations for both the water and hydroxyl units. Two bands ascribed to water are observed at 3276 and 3072 cm-1. Three hydroxyl stretching vibrations are observed. Calculations using a Libowitzky type formula show that the hydrogen bond distances of the water molecules are 2.745 and 2.812 Å which are considerably shorter than the values for the hydroxyl units 2.896, 2.917 and 2.978 Å. Two phosphate stretching vibrations at 1042 and 1062 cm-1 in line with the two independent phosphate units in the structure of chalcosiderite. Three bands are observed at 1102, 1159 and 1194 cm-1 assigned to the phosphate antisymmetric stretching vibrations. FGA predicts six bands but only three are observed due to accidental degeneracy. Both the ν2 and ν4 bending regions are complex. Four Raman bands observed at 536, 580, 598 and 636 cm-1 are assigned to the ν4 bending modes. Raman bands at 415, 420, 475 and 484 cm-1are assigned to the phosphate ν2 bending modes. Vibrational spectroscopy enables aspects of the molecular structure of chalcosiderite to be assessed.

Preservation and promotion of bone formation in the mandible as a response to a novel calcium-phosphate based biomaterial in mineral deficiency induced low bone mass male versus female rats

PubMed Central

Srinivasan, Kritika; Naula, Diana P.; Mijares, Dindo Q.; Janal, Malvin N.; LeGeros, Raquel Z.; Zhang, Yu

2016-01-01

Calcium and other trace mineral supplements have previously demonstrated to safely improve bone quality. We hypothesize that our novel calcium-phosphate based biomaterial (SBM) preserves and promotes mandibular bone formation in male and female rats on mineral deficient diet (MD). Sixty Sprague-Dawley rats were randomly assigned to receive one of three diets (n = 10): basic diet (BD), MD or mineral deficient diet with 2% SBM. Rats were sacrificed after 6 months. Micro-Computed Tomography (μCT) was used to evaluate bone volume and 3D-microarchitecture while microradiography (Faxitron) was used to measure bone mineral density from different sections of the mandible. Results showed that bone quality varied with region, gender and diet. MD reduced bone mineral density (BMD) and volume and increased porosity. SBM preserved BMD and bone mineral content (BMC) in the alveolar bone and condyle in both genders. In the alveolar crest and mandibular body, while preserving more bone in males, SBM also significantly supplemented female bone. Results indicate that mineral deficiency leads to low bone mass in skeletally immature rats, comparatively more in males. Furthermore, SBM administered as a dietary supplement was effective in preventing mandibular bone loss in all subjects. This study suggests that the SBM preparation has potential use in minimizing low peak bone mass induced by mineral deficiency and related bone loss irrespective of gender. PMID:26914814

Stable Isotope Analyses of Phosphate Oxygen From Micro-samples of Biological Apatite: A new Routine Procedure for Silverphosphate Micro-precipitation and the Removal of Organic Contamination

NASA Astrophysics Data System (ADS)

Wiedemann-Bidlack, F. B.; Colman, A. S.; Fogel, M. L.

2003-12-01

Oxygen isotope analyses in bone and teeth of living and fossil animals are widely used for testing hypotheses about variability of diet and habitat. For the analysis of environmental or dietary changes in the past, tooth enamel has become the preferred study material, because its mineral content is higher than bone and dentine, and the relatively large size of the carbonato-apatite crystals of enamel make it more stable against post mortem diagenetic alteration than dentine or bone. Intra-tooth sampling of dental enamel is increasingly used for the investigation of seasonal climate variability, taking advantage of both the high correlation between an animal's drinking water and the δ 18O in its mineralized tissues and the incremental growth pattern of tooth enamel. The different oxygen-containing ions of bioapatite (phosphate, carbonate, and hydroxyl group) incorporate into the mineral lattice at different rates during enamel mineralization, and differ in their susceptibility against post mortem diagenetic alteration. In addition, it is difficult to account for the different reaction chemistries of phosphate, carbonate, and hydroxyl group using isotope analysis techniques that include all oxygen contained in the enamel (e.g., laser ablation). These problems can be addressed analyzing phosphate oxygen only. However, two major factors limit the potential of δ 18O analyses in dental enamel: A) the starting sample size for isotope analyzes often precludes the use of small teeth or the intra-tooth sampling of a given tooth; B) Small amounts of biogenic organic material in tooth enamel (less than 1% by wt) can reduce the precision and lead to anomalous analytical results in δ 18O measurements on Ag3PO4 produced from tooth enamel. A new procedure was developed for the pre-treatment and δ 18O analysis of phosphate from small samples (500 μ g) of tooth enamel containing organic matter. Ag3PO{4} was precipitated quantitatively for analysis of δ 18Ophosphate using a Thermoquest-Finnigan TC/EA coupled to Delta Plus XL. A sodium hypochlorite sample pre-treatment step was determined to remove organic matter quantitatively without altering the isotopic composition of the phosphate oxygen. The reproducibility of δ 18O values for pretreated samples (0.2-0.3 ‰ , 1σ ) is much better than for samples without pre-treatment (1.2 ‰ , 1σ ). Phosphate oxygen isotope standards processed using this technique gave measured values indistinguishable from the standard composition, demonstrating the accuracy of the new technique.

Phosphatized algal-bacterial assemblages in Late Cretaceous phosphorites of the Voronezh Anteclise

NASA Astrophysics Data System (ADS)

Maleonkina, Svetlana Y.

2003-01-01

Late Cretaceous phosphogenesis of the Voronezh Anteclise has occurred during Cenomanian and Early Campanian. SEM studies show the presence of phosphatized algal-bacterial assemblages both in Cenomanian and Campanian phosphorites. In some Cenomanian nodular phosphorite samples revealed empty tubes 1 - 5 microns in diameter, which are most likely trichomes of cyanobacterial filaments. Other samples contained accumulations of spheres 0,5-3 microns, similar to coccoidal bacteria. Complicated tubular forms with variable diameter 2 - 5 microns occur on surface of some quartz grains in nodules. They are probably pseudomorphs after algae. We found similar formations in the Campanian phosphate grains. Frequently, grain represents a cyanobacterial mat, which is sometimes concentrically coated by phosphatic films. The films of some grains retain the primary structure, their concentric layers are formed by pseudomorphs after different bacterial types and obviously they represent oncolite. In other cases, the primary structure is unobservable because of recrystallization process erases them. Occasionally, the central part retains the coccoidal structure and the recrystallization affects only films. Besides the core of such oncolite can be represented not only by phosphatic grain, but also by grains of other minerals, such as quartz, glauconite and heavy minerals, which serve as a substrate for cyanobacterial colonies. Bacteria also could settle on cavity surfaces and interiors frames of sponge fragments, teeth and bones.

Macroporous Calcium Phosphate/Chitosan Composites Prepared via Unidirectional Ice Segregation and Subsequent Freeze-Drying

PubMed Central

Aranaz, Inmaculada; Martínez-Campos, Enrique; Moreno-Vicente, Carolina; Civantos, Ana; García-Arguelles, Sara; del Monte, Francisco

2017-01-01

Calcium phosphate chitosan-based composites have gained much interest in recent years for biomedical purposes. In this paper, three-dimensional calcium phosphate chitosan-based composites with different mineral contents were produced using a green method called ice segregation induced self-assembly (ISISA). In this methodology, ice crystals were used as a template to produce porous structures from an aqueous solution of chitosan (CS) and hydroxyapatite (Hap) also containing acetic acid (pH = 4.5). For better characterization of the nature of the inorganic matter entrapped within the resulting composite, we performed either oxygen plasma or calcination processes to remove the organic matter. The nature of the phosphate salts was studied by XRD and NMR studies. Amorphous calcium phosphate (ACP) was identified as the mineral phase in the composites submitted to oxygen plasma, whereas crystalline Hap was obtained after calcination. SEM microscopy revealed the formation of porous structures (porosity around 80–85%) in the original composites, as well as in the inorganic matrices obtained after calcination, with porous channels of up to 50 µm in diameter in the former case and of up to 20 µm in the latter. The biocompatibility of the composites was assessed using two different cell lines: C2C12GFP premyoblastic cells and MC3T3 preosteoblastic cells. PMID:28772874

Characterization and obtainment of phosphate rock concentrates of Turmequé, Boyacá

NASA Astrophysics Data System (ADS)

Zanguña, S. Quijano; Lozano Gómez, L. F.; Pineda Triana, Y.

2017-12-01

The work focuses on the use and exploitation of the mineral concentrates from phosphate rock (PR) coming from mines with a low percentage of phosphorus. The procedure was based on the collection of a source of phosphate rock from the department of Boyacá (municipality of Turmequé), using a randomized design with three replications. The samples were initially milled and sifted using meshes between 140 and 200 US standard, homogenizing them and improving the process of solubility of the phosphorus in the soil. We conduced Z-potential tests, which show that by performing a prior wash on the mineral and maintaining certain concentrations and pH defined, better results are achieved in terms of the buoyancy of the particles in the flotation process. The results obtained from the microflotation tests; both direct and inverse, and the results of chemical composition, with X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD), before and after the microflotation process, were carried out to obtain of commercial laws grade phosphate rock concentrate, confirm that the protocol used increases by 9% the value of total phosphorus in the collected sample. These concentrates from phosphate rock, could be used in the future for the attainment of simple superphosphate (SSP), with the help of sulphuric acid and ammonium thiosulphate mixtures.

Protein scaffolds for selective enrichment of metal ions

DOEpatents

He, Chuan; Zhou, Lu; Bosscher, Michael

2016-02-09

Polypeptides comprising high affinity for the uranyl ion are provided. Methods for binding uranyl using such proteins are likewise provided and can be used, for example, in methods for uranium purification or removal.

Uranyl(VI) nitrate salts: modeling thermodynamic properties using the binding mean spherical approximation theory and determination of "fictive" binary data.

PubMed

Ruas, Alexandre; Bernard, Olivier; Caniffi, Barbara; Simonin, Jean-Pierre; Turq, Pierre; Blum, Lesser; Moisy, Philippe

2006-02-23

This work is aimed at a description of the thermodynamic properties of highly concentrated aqueous solutions of uranyl nitrate at 25 degrees C. A new resolution of the binding mean spherical approximation (BIMSA) theory, taking into account 1-1 and also 1-2 complex formation, is developed and used to reproduce, from a simple procedure, experimental uranyl nitrate osmotic coefficient variation with concentration. For better consistency of the theory, binary uranyl perchlorate and chloride osmotic coefficients are also calculated. Comparison of calculated and experimental values is made. The possibility of regarding the ternary system UO(2)(NO(3))(2)/HNO(3)/H(2)O as a "simple" solution (in the sense of Zdanovskii, Stokes, and Robinson) is examined from water activity and density measurements. Also, an analysis of existing uranyl nitrate binary data is proposed and compared with our obtained data. On the basis of the concept of "simple" solution, values for density and water activity for the binary system UO(2)(NO(3))(2)/H(2)O are proposed in a concentration range on which uranyl nitrate precipitates from measurements on concentrated solutions of the ternary system UO(2)(NO(3))(2)/HNO(3)/H(2)O. This new set of binary data is "fictive" in the sense that the real binary system is not stable chemically. Finally, a new, interesting predictive capability of the BIMSA theory is shown.

The role of phosphates for the Lu-Hf chronology of meteorites

NASA Astrophysics Data System (ADS)

Debaille, Vinciane; Van Orman, James; Yin, Qing-Zhu; Amelin, Yuri

2017-09-01

The 176Lu-176Hf isotopic system is widely used for dating and tracing cosmochemical and geological processes, but still suffers from two uncertainties. First, Lu-Hf isochrons for some early Solar System materials have excess slope of unknown origin that should not be expected for meteorites with ages precisely determined with other isotopic chronometers. This observation translates to an apparent Lu decay constant higher than the one calculated by comparing ages obtained with various dating methods on terrestrial samples. Second, unlike the well constrained Sm/Nd value (to within 2%) for the chondritic uniform reservoir (CHUR), the Lu/Hf ratios in chondrites vary up to 18% when considering all chondrites, adding uncertainty to the Lu/Hf CHUR value. In order to better understand the Lu-Hf systematics of chondrites, we analyzed mineral fractions from the Richardton H5 chondrite to construct an internal Lu-Hf isochron, and set up a numerical model to investigate the effect of preferential diffusion of Lu compared to Hf from phosphate, the phase with the highest Lu-Hf ratio in chondrites, to other minerals. The isochron yields an age of 4647 ± 210 million years (Myr) using the accepted 176Lu decay constant of 1.867 ± 0.008 ×10-11yr-1. Combining this study with the phosphate fractions measured in a previous study yields a slope of 0.08855 ± 0.00072, translating to a 176Lu decay constant of 1.862 ± 0.016 ×10-11yr-1 using the Pb-Pb age previously obtained, in agreement with the accepted value. The large variation of the Lu/Hf phosphates combined with observations in the present study identify phosphates as the key in perturbing Lu-Hf dating and generating the isochron slope discrepancy. This is critical as apatite has substantially higher diffusion rates of rare earth elements than most silicate minerals that comprise stony meteorites. Results of numerical modeling depending of temperature peak, size of the grains and duration of the metamorphic event, show that diffusion processes in phosphate can produce an apparently older Lu-Hf isochron, while this effect will remain negligible in perturbing the Sm-Nd chronology. Our results suggest that only type 3 chondrites with the lowest metamorphic grade and large minerals with minimal diffusive effects are suitable for determination of the Lu-Hf CHUR values and the Lu decay constant respectively.

Effect of phytase from Aspergillus niger on plant growth and mineral assimilation in wheat (Triticum aestivum Linn.) and its potential for use as a soil amendment.

PubMed

Gujar, Pradnya D; Bhavsar, Kavita P; Khire, Jayant M

2013-07-01

Extensive use of non-replenishable phosphate reserves as phosphate supplements in agriculture and animal feed poses a threat for environmental pollution and necessitated a search for alternative phosphate sources. Unlocking the phytate phosphorus using microbial phytase can provide an ecofriendly solution in agriculture. The aim of the present work was to evaluate the effect of phytase from Aspergillus niger NCIM 563 in degradation of phytate phosphorus to benefit plant nutrition and soil amendment in comparison with chemical fertilizers. An enzyme dose of 12 IU was sufficient to hydrolyze phytate and increase assimilation of phosphorus by about 74%. Phytase supplementation leads to increase in shoot:total length ratio by about 200%, indicating its growth-promoting effect. Consistency in phytase-induced growth was reflected at pot and tray levels, wherein shoot:total length ratio was observed to be 2.01 and 2.12 respectively. Mineral assimilation due to phytase was more efficient as compared to chemical fertilizers, thus overcoming the constraints of practicability and economics in the agriculture industry. Phytase was efficient in reducing the phytic acid content of soil by about 30% while simultaneously increasing the phytate phosphate availability by 1.18-fold. Phytase from A. niger showed improvement in phytate phosphorus and mineral availability. Besides a plant growth-promoting effect, reduction in use of chemical fertilizers and soil improvement could be achieved simultaneously for maintaining the sustainability of agriculture. © 2012 Society of Chemical Industry.

Recognizing the Effects of Terrestrial Contamination on D/H Ratios in Shergottite Phosphates

NASA Technical Reports Server (NTRS)

Ross, D. K.; Ito, M.; Hervig, R.; Rao, M. N.; Nyquist, L. E.

2011-01-01

Hydrogen isotope ratios in shergottite phosphate minerals have been investigated by SIMS in the meteorites Queen Alexandra Range (QUE) 94201 and Los Angeles. We have also collected electron probe data on these phosphates in order to characterize the phosphate minerals and attempt to document any potential hydrogen isotopic differences between chlor-apatite and whitlockite. In the section of Los Angeles we studied (748), we found both chlor-apatite and whitlockite, but in the section of QUE 94201,38 studied, we found only whitlockite. In both meteorites, D/H ratios (expressed in units of delta D (sub SMOW) vary, from terrestrial values up to approximately 5400%o in QUE 94201, and to approximately 3800%o in Los Angeles. We have carefully examined the ion probed pits with high-resolution FE-SEM. In most cases where the D/H ratios are low, we have iden-tified cracks that instersect the ion probe pit. These cracks are not visible in the optical microscope attached to the SIMS instument, making them impossible to avoid during SIMS data collection. We contend that the low ratios are a function of substantial terrestrial contamination, and that similar contamination is a likely factor in previously published studies on D/H ratios in martian phosphates. Here we highlight the difficulty of attempts to constrain the martian mantle D/H ratio using phosphate data, given that both terrestrial contamination and martian mantle hydrogen will move phosphate D/H ratios in the same direction, toward lower values. We note that our data include some of the most deuterium-rich values ever reported for martian phosphates. It is clear that some of our measurements are only minimally or totally uncontaminated, but the question arises, are intermediate values diminished because of true martian variability, or do they reflect contamination?

30 CFR 46.3 - Training plans.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Training plans. 46.3 Section 46.3 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR EDUCATION AND TRAINING TRAINING AND..., COLLOIDAL PHOSPHATE, OR SURFACE LIMESTONE MINES. § 46.3 Training plans. (a) You must develop and implement a...

Engineered nano-magnetic iron oxide-urea-activated carbon nanolayer sorbent for potential removal of uranium (VI) from aqueous solution

NASA Astrophysics Data System (ADS)

Mahmoud, Mohamed E.; Khalifa, Mohamed A.; El Wakeel, Yasser M.; Header, Mennatllah S.; Abdel-Fattah, Tarek M.

2017-04-01

A novel magnetic nanosorbent was designed using chemical grafting of nano-magnetite (Nano-Fe3O4) with nanolayer of activated carbon (AC) via urea intermediate for the formation of Nano-Fe3O4-Urea-AC. Characterizing was carried out using FT-IR, SEM, HR-TEM, TGA, point of zero charge (Pzc) and surface area analysis. The designed sorbent maintained its magnetic properties and nanosized structure in the range of 8.7-14.1 nm. The surface area was identified as 389 m2/g based on the BET method. Sorption of uranyl ions from aqueous solutions was studied and evaluated in different experimental conditions. Removal of uranyl ions increased with increasing in pH value and the maximum percentage removal was established at pH 5.0. The removal and sorption processes of uranyl ions by Nano-Fe3O4-Urea-AC sorbent were studied and optimized using the batch technique. The key variables affecting removal of uranyl ions were studied including the effect of the contact time, dosage of Nano-Fe3O4-Urea-AC sorbent, reaction temperature, initial uranyl ions concentration and interfering anions and cations.

Immobilization of selenate by iron in aqueous solution under anoxic conditions and the influence of uranyl

NASA Astrophysics Data System (ADS)

Puranen, Anders; Jonsson, Mats; Dähn, Rainer; Cui, Daqing

2009-08-01

In proposed high level radioactive waste repositories a large part of the spent nuclear fuel (SNF) canisters are commonly composed of iron. Selenium is present in spent nuclear fuel as a long lived fission product. This study investigates the influence of iron on the uptake of dissolved selenium in the form of selenate and the effect of the presence of dissolved uranyl on the above interaction of selenate. The iron oxide, and selenium speciation on the surfaces was investigated by Raman spectroscopy. X-ray Absorption Spectroscopy was used to determine the oxidation state of the selenium and uranium on the surfaces. Under the simulated groundwater conditions (10 mM NaCl, 2 mM NaHCO 3, <0.1 ppm O 2) the immobilized selenate was found to be reduced to oxidation states close to zero or lower and uranyl was found to be largely reduced to U(IV). The near simultaneous reduction of uranyl was found to greatly enhance the rate of selenate reduction. These findings suggest that the presence of uranyl being reduced by an iron surface could substantially enhance the rate of reduction of selenate under anoxic conditions relevant for a repository.

Tris-amidoximate uranyl complexes via η2 binding mode coordinated in aqueous solution shown by X-ray absorption spectroscopy and density functional theory methods.

PubMed

Zhang, Linjuan; Qie, Meiying; Su, Jing; Zhang, Shuo; Zhou, Jing; Li, Jiong; Wang, Yu; Yang, Shitong; Wang, Shuao; Li, Jingye; Wu, Guozhong; Wang, Jian Qiang

2018-03-01

The present study sheds some light on the long-standing debate concerning the coordination properties between uranyl ions and the amidoxime ligand, which is a key ingredient for achieving efficient extraction of uranium. Using X-ray absorption fine structure combined with theoretical simulation methods, the binding mode and bonding nature of a uranyl-amidoxime complex in aqueous solution were determined for the first time. The results show that in a highly concentrated amidoxime solution the preferred binding mode between UO 2 2+ and the amidoxime ligand is η 2 coordination with tris-amidoximate species. In such a uranyl-amidoximate complex with η 2 binding motif, strong covalent interaction and orbital hybridization between U 5f/6d and (N, O) 2p should be responsible for the excellent binding ability of the amidoximate ligand to uranyl. The study was performed directly in aqueous solution to avoid the possible binding mode differences caused by crystallization of a single-crystal sample. This work also is an example of the simultaneous study of local structure and electronic structure in solution systems using combined diagnostic tools.

Adsorption and release of amino acids mixture onto apatitic calcium phosphates analogous to bone mineral

NASA Astrophysics Data System (ADS)

El Rhilassi, A.; Mourabet, M.; El Boujaady, H.; Bennani-Ziatni, M.; Hamri, R. El; Taitai, A.

2012-10-01

Study focused on the interaction of adsorbate with poorly crystalline apatitic calcium phosphates analogous to bone mineral. Calcium phosphates prepared in water-ethanol medium at physiological temperature (37 °C) and neutral pH, their Ca/P ratio was between 1.33 and 1.67. Adsorbate used in this paper takes the mixture form of two essential amino acids L-lysine and DL-leucine which have respectively a character hydrophilic and hydrophobic. Adsorption and release are investigated experimentally; they are dependent on the phosphate type and on the nature of adsorbate L-lysine, DL-leucine and their mixture. Adsorption of mixture of amino acids on the apatitic calcium phosphates is influenced by the competition between the two amino acids: L-lysine and DL-leucine which exist in the medium reaction. The adsorption kinetics is very fast while the release kinetics is slow. The chemical composition of apatite has an influence on both adsorption and release. The interactions adsorbate-adsorbent are electrostatic type. Adsorption and release reactions of the amino acid mixture are explained by the existence of the hydrated surface layer of calcium phosphate apatite. The charged sbnd COOsbnd and sbnd NH3+ of adsorbates are the strongest groups that interact with the surface of apatites, the adsorption is mainly due to the electrostatic interaction between the groups sbnd COOsbnd of amino acids and calcium Ca2+ ions of the apatite. Comparative study of interactions between adsorbates (L-lysine, DL-leucine and their mixture) and apatitic calcium phosphates is carried out in vitro by using UV-vis and infrared spectroscopy IR techniques.

A Study of Intumescent Reaction Mechanisms.

DTIC Science & Technology

1984-08-01

Neoprene Fibers Considered Asbestos Metal Fiber (Steel Wool) Kevlar Mica Glass Fiber Mineral Wool Graphite Refrasil -7- • . . . ’ .. I , "’ - . NADC-84 170...Kevlar o Flexible Epoxy e Metal Fiber (Steel Wool) * Mineral Wool Fillers * Borax * Sodium Metasilicate * Ammonium Phosphate o Aluminum Sulfate...reference tables in Section 2.0] . The mineral wool appears to be the least effec- tive of the five fibers. To optimize thermal performance for a set of

Element mobilization and redistribution under extreme tropical weathering of basalts from the Hainan Island, South China

NASA Astrophysics Data System (ADS)

Jiang, Ke; Qi, Hua-Wen; Hu, Rui-Zhong

2018-06-01

Chemical weathering of rocks has substantial influence on the global geochemical cycle. In this paper, the geochemical profile of a well-developed basalt weathering profile (>15 m thick, including soil, saprolite, semi-weathered rock and fresh basalt) on the Island of Hainan (South China) was presented. The soil and saprolite samples from this profile are characterized by high Al2O3 and Fe2O3 concentrations (up to 32.3% and 28.5%, respectively). The mineral assemblage is dominated by kaolinite, Fe-oxides/-hydroxides and gibbsite (or boehmite), indicating extensive desilicate and ferrallitic weathering. The acidic and organic-rich environment in the soil horizon may have promoted elemental remobilization and leaching. The strongest SiO2 depletion and Al2O3 enrichment at about 2.4 m deep indicate that the main kaolinite hydrolysis and gibbsite formation occurred near the soil-saprolite interface. The mild Sr reconcentration at about 3.9 m and 7.1 m deep may be attributed to secondary carbonate precipitation. Mn-oxides/-hydroxides precipitated at 6.1 m deep, accompanied by the strongest enrichment of Ba and Co. Uranium is mildly enriched in the middle part (about 7.1 m and 9.1 m deep) of the weathering profile, and the enrichment may have been caused by the decomposition of uranyl carbonates or the accumulation of zircon. Immobile element (i.e., Zr, Hf, Nb, Ta, Th and Ti) distributions at different depths are mainly controlled by secondary Fe-oxides/-hydroxides, and follow the stability sequence of Nb ≈ Ta ≈ Th > Zr ≈ Hf > Ti. The limited thickness (∼15 cm) of the semi-weathered basalt horizon at the rock-regolith interface (15.28 m deep) suggests that plagioclase and pyroxene are readily altered to kaolinite, smectite and Fe-oxides under tropical climate. The marked enrichment of transitional metals (such as Cu, Zn, Ni, and Sc) along the rock-regolith interface may have associated mainly with increasing pH values, as well as the dissolution of primary apatite and formation of secondary phosphates. Our findings highlight the importance of secondary phosphates in the redistribution of transition metals, and in the possible Mg, Cu, and Ni isotopic fractionation under extreme weathering of basalt in tropic climate.

Phosphate Biomineralization of Cambrian Microorganisms

NASA Technical Reports Server (NTRS)

McKay, David S.; Rozanov, Alexei Yu.; Hoover, Richard B.; Westall, Frances

1998-01-01

As part of a long term study of biological markers (biomarkers), we are documenting a variety of features which reflect the previous presence of living organisms. As we study meteorites and samples returned from Mars, our main clue to recognizing possible microbial material may be the presence of biomarkers rather than the organisms themselves. One class of biomarkers consists of biominerals which have either been precipitated directly by microorganisms, or whose precipitation has been influenced by the organisms. Such microbe-mediated mineral formation may include important clues to the size, shape, and environment of the microorganisms. The process of fossilization or mineralization can cause major changes in morphologies and textures of the original organisms. The study of fossilized terrestrial organisms can help provide insight into the interpretation of mineral biomarkers. This paper describes the results of investigations of microfossils in Cambrian phosphate-rich rocks (phosphorites) that were found in Khubsugul, Northern Mongolia.

Coordination characteristics of uranyl BBP complexes: Insights from an electronic structure analysis

DOE PAGES

Pemmaraju, Chaitanya Das; Copping, Roy; Smiles, Danil E.; ...

2017-03-21

Here, organic ligand complexes of lanthanide/actinide ions have been studied extensively for applications in nuclear fuel storage and recycling. Several complexes of 2,6-bis(2-benzimidazyl)pyridine (H2BBP) featuring the uranyl moiety have been reported recently, and the present study investigates the coordination characteristics of these complexes using density functional theory-based electronic structure analysis. In particular, with the aid of several computational models, the nonplanar equatorial coordination about uranyl, observed in some of the compounds, is studied and its origin traced to steric effects.

Application of electron probe X-ray microanalysis to calcification studies of bone and cartilage.

PubMed

Landis, W J

1979-01-01

The use of electron probe x-ray microanalysis in previous studies of bone and cartilage has been reviewed with emphasis on the results which have contributed to some of the current concepts of the mechanism of mineralization in these tissues. A number of investigations continuing in the author's laboratory utilizing high spatial resolution x-ray microanalysis and anhydrous methods of specimen preparation are described, including aspects concerning the derivation of calibration curves from synthetic calcium phosphate solids, qualitative and quantitative analyses of calcium and phosphorus in bone from embryonic chicks and in growth plate cartilage from rats, and the role of organically-bound phosphorus in mineralizing tissues. The data obtained have helped identify brushite, CaHPO4-2H2O, as the major crystalline solid phase of calcium phosphate in the earliest mineral deposits of bone tissue, brushite and poorly crystalline hydroxyapatite in bone mineral of increasing age, and poorly crystalline hydroxyapatite in the most mature mineral portions of the tissue. Growth plate cartilage examination has revealed calcium and phosphorus in single mitochondrial granules within chondrocytes and in certain extracellular particles distinct from matrix vesicles. These results have provided important information about the possible roles of cells, extracellular components, and the organic matrix in the regulation of mineralization and about the composition, structure, and organization of the mineral phase as a function of progressively increasing age and maturation of the tissues studied.

Degradation processes of reinforced concretes by combined sulfate–phosphate attack

DOE Office of Scientific and Technical Information (OSTI.GOV)

Secco, Michele, E-mail: michele.secco@unipd.it; Department of Civil, Environmental and Architectural Engineering; Lampronti, Giulio Isacco, E-mail: gil21@cam.ac.uk

2015-02-15

A novel form of alteration due to the interaction between hydrated cement phases and sulfate and phosphate-based pollutants is described, through the characterization of concrete samples from an industrial reinforced concrete building. Decalcification of the cement matrices was observed, with secondary sulfate and phosphate-based mineral formation, according to a marked mineralogical and textural zoning. Five alteration layers may be detected: the two outermost layers are characterized by the presence of gypsum–brushite solid solution phases associated with anhydrous calcium sulfates and phosphates, respectively, while a progressive increase in apatite and ammonium magnesium phosphates is observable in the three innermost layers, associatedmore » with specific apatite precursors (brushite, octacalcium phosphate and amorphous calcium phosphate, respectively). The heterogeneous microstructural development of secondary phases is related to the chemical, pH and thermal gradients in the attacked cementitious systems, caused by different sources of pollutants and the exposure to the sun's radiation.« less

Exploring New Assembly Modes of Uranyl Terephthalate: Templated Syntheses and Structural Regulation of a Series of Rare 2D → 3D Polycatenated Frameworks

DOE PAGES

Mei, Lei; Wang, Cong-zhi; Zhu, Liu-zheng; ...

2017-06-23

In this paper, the reaction of uranyl nitrate with terephthalic acid (H 2TP) under hydrothermal conditions in the presence of an organic base, 1,3-(4,4'-bispyridyl)propane (BPP) or 4,4'-bipyridine (BPY), provided four uranyl terephthalate compounds with different entangled structures by a pH-tuning method. [UO 2(TP) 1.5](H 2BPP) 0.5·2H 2O (1) obtained in a relatively acidic solution (final aqueous pH, 4.28) crystallizes in the form of a noninterpenetrated honeycomb-like two-dimensional network structure. An elevation of the solution pH (final pH, 5.21) promotes the formation of a dimeric uranyl-mediated polycatenated framework, [(UO 2) 2(μ-OH) 2(TP) 2] 2(H 2BPP) 2·4.5H 2O (2). Another new polycatenatedmore » framework with a monomeric uranyl unit, [(UO 2) 2(TP) 3](H 2BPP) (3), begins to emerge as a minor accompanying product of 2 when the pH is increased up to 6.61, and turns out to be a significant product at pH 7.00. When more rigid but small-size BPY molecules replace BPP molecules, [UO 2(TP) 1.5](H 2BPP) 0.5 (4) with a polycatenated framework similar to 3 was obtained in a relatively acidic solution (final pH, 4.81). The successful preparation of 2–4 represents the first report of uranyl–organic polycatenated frameworks derived from a simple H 2TP linker. Finally, a direct comparison between these polycatenated frameworks and previously reported uranyl terephthalate compounds suggests that the template and cavity-filling effects of organic bases (such as BPP or BPY), in combination with specific hydrothermal conditions, promote the formation of uranyl terephthalate polycatenated frameworks.« less

An investigation of the mineral in ductile and brittle cortical mouse bone.

PubMed

Rodriguez-Florez, Naiara; Garcia-Tunon, Esther; Mukadam, Quresh; Saiz, Eduardo; Oldknow, Karla J; Farquharson, Colin; Millán, José Luis; Boyde, Alan; Shefelbine, Sandra J

2015-05-01

Bone is a strong and tough material composed of apatite mineral, organic matter, and water. Changes in composition and organization of these building blocks affect bone's mechanical integrity. Skeletal disorders often affect bone's mineral phase, either by variations in the collagen or directly altering mineralization. The aim of the current study was to explore the differences in the mineral of brittle and ductile cortical bone at the mineral (nm) and tissue (µm) levels using two mouse phenotypes. Osteogenesis imperfecta model, oim(-/-) , mice have a defect in the collagen, which leads to brittle bone; PHOSPHO1 mutants, Phospho1(-/-) , have ductile bone resulting from altered mineralization. Oim(-/-) and Phospho1(-/-) were compared with their respective wild-type controls. Femora were defatted and ground to powder to measure average mineral crystal size using X-ray diffraction (XRD) and to monitor the bulk mineral to matrix ratio via thermogravimetric analysis (TGA). XRD scans were run after TGA for phase identification to assess the fractions of hydroxyapatite and β-tricalcium phosphate. Tibiae were embedded to measure elastic properties with nanoindentation and the extent of mineralization with backscattered electron microscopy (BSE SEM). Results revealed that although both pathology models had extremely different whole-bone mechanics, they both had smaller apatite crystals, lower bulk mineral to matrix ratio, and showed more thermal conversion to β-tricalcium phosphate than their wild types, indicating deviations from stoichiometric hydroxyapatite in the original mineral. In contrast, the degree of mineralization of bone matrix was different for each strain: brittle oim(-/-) were hypermineralized, whereas ductile Phospho1(-/-) were hypomineralized. Despite differences in the mineralization, nanoscale alterations in the mineral were associated with reduced tissue elastic moduli in both pathologies. Results indicated that alterations from normal crystal size, composition, and structure are correlated with reduced mechanical integrity of bone. © 2014 American Society for Bone and Mineral Research.

Preliminary experiments on the reduction of the uranyl ion to uraninite by carbonaceous substances

USGS Publications Warehouse

Breger, Irving A.; Moore, Richard T.

1955-01-01

An aqueous solution of uranyl sulfate containing a suspension of subbituminous coal has been heated at 210 C for three days. Examination of the coal at the end of the experiment showed it to contain 31.8 percent uranium recognizable as uraninite by a sharp, strong X-ray diffraction pattern. A similar experiment with degraded spruce wood also led to the formation of uraninite but in lesser quantity and with broader lines in the X-ray diffraction pattern. The ability of coal or wood to reduce the uranyl ion is a critical factor in the correlation of studies of uraniferous coals containing the uranyl ion with studies of uraninite-bearing coalified wood from the Colorado Plateau. Although these results are based an preliminary experiments, they are extremely important geochemically and warrant the development of the series of controlled studies that are proposed.

DOE/SC0001389 Final technical report: Investigation of uranium attenuation and release at column and pore scales in response to advective geochemical gradients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Savage, Kaye S.; Zhu, Wenyi; Barnett, Mark O.

2013-05-13

Experimental approach Column experiments were devised to investigate the role of changing fluid composition on mobility of uranium through a sequence of geologic media. Fluids and media were chosen to be relevant to the ground water plume emanating from the former S-3 ponds at the Oak Ridge Integrated Field Research Challenge (ORIFC) site. Synthetic ground waters were pumped upwards at 0.05 mL/minute for 21 days through layers of quartz sand alternating with layers of uncontaminated soil, quartz sand mixed with illite, quartz sand coated with iron oxides, and another soil layer. Increases in pH or concentration of phosphate, bicarbonate, ormore » acetate were imposed on the influent solutions after each 7 pore volumes while uranium (as uranyl) remained constant at 0.1mM. A control column maintained the original synthetic groundwater composition with 0.1mM U. Pore water solutions were extracted to assess U retention and release in relation to the advective ligand or pH gradients. Following the column experiments, subsamples from each layer were characterized using microbeam X-ray absorption spectroscopy (XANES) in conjunction with X-ray fluorescence mapping and compared to sediment core samples from the ORIFC, at SSRL Beam Line 2-3. Results U retention of 55-67mg occurred in phosphate >pH >control >acetate >carbonate columns. The mass of U retained in the first-encountered quartz layer in all columns was highest and increased throughout the experiment. The rate of increase in acetate- and bicarbonate-bearing columns declined after ligand concentrations were raised. U also accumulated in the first soil layer; the pH-varied column retained most, followed by the increasing-bicarbonate column. The mass of U retained in the upper layers was far lower. Speciation of U, interpreted from microbeam XANES spectra and XRF maps, varied within and among the columns. Evidence of minor reduction to U(IV) was observed in the first-encountered quartz layer in the phosphate, bicarbonate, and pH columns while only U(VI) was observed in the control and acetate columns. In the soil layer, the acetate and bicarbonate columns both indicate minor reduction to U(IV), but U(VI) predominated in all columns. In the ORIFC soils, U was consistently present as U(VI); sorption appears to be the main mechanism of association for U present with Fe and/or Mn, while U occurring with P appears in discrete particles consistent with a U mineral phase. U in soil locations with no other elemental associations shown by XRF are likely uranium oxide phases.« less

In Situ Evaluation of Calcium Phosphate Nucleation Kinetics and Pathways during Intra- and Extrafibrillar Mineralization of Collagen Matrices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Doyoon; Lee, Byeongdu; Thomopoulos, Stavros

Calcium phosphate (CaP) nanocrystals nucleate and grow in intrafibrillar and/or extrafibrillar spaces of collagen fibrils during the mineralization of bones and teeth. Little is known about the early stages of CaP nucleation and distribution in fibrillar matrices, despite their significant influence on the physical and chemical structures of tissue-level constructs. Using in situ small angle X-ray scattering (SAXS), we examined the nucleation and growth of CaP within collagen matrices and elucidated how a nucleation inhibitor, polyaspartic acid (pAsp), governs mineralization kinetics and pathways at multiple length scales. In situ SAXS analysis clearly revealed that nucleation sites, kinetically-controlled by the nucleationmore » inhibitor, determined the pathways of CaP morphological transformation. Mineralization with pAsp led to intrafibrillar CaP plates with a spatial distribution gradient through the depth of the matrix. Mineralization without pAsp led initially to spherical aggregates of CaP in the entire extrafibrillar spaces. With time, the spherical aggregates transformed into plates at the outermost surface of the collagen matrix, preventing intrafibrillar mineralization inside. The results illuminate mineral nucleation kinetics and real-time nanoparticle distributions within organic matrices in solutions containing body fluid components. Because the macroscale mechanical properties of collagen matrices depend on their mineral content, phase, and arrangement at the nanoscale, this study contributes to better design and fabrication of biomaterials for regenerative medicine.« less

Behavior of uranium under conditions of interaction of rocks and ores with subsurface water

NASA Astrophysics Data System (ADS)

Omel'Yanenko, B. I.; Petrov, V. A.; Poluektov, V. V.

2007-10-01

The behavior of uranium during interaction of subsurface water with crystalline rocks and uranium ores is considered in connection with the problem of safe underground insulation of spent nuclear fuel (SNF). Since subsurface water interacts with crystalline rocks formed at a high temperature, the mineral composition of these rocks and uranium species therein are thermodynamically unstable. Therefore, reactions directed toward the establishment of equilibrium proceed in the water-rock system. At great depths that are characterized by hindered water exchange, where subsurface water acquires near-neutral and reducing properties, the interaction is extremely sluggish and is expressed in the formation of micro- and nanoparticles of secondary minerals. Under such conditions, the slow diffusion redistribution of uranium with enrichment in absorbed forms relative to all other uranium species is realized as well. The products of secondary alteration of Fe- and Ti-bearing minerals serve as the main sorbents of uranium. The rate of alteration of minerals and conversion of uranium species into absorbed forms is slow, and the results of these processes are insignificant, so that the rocks and uranium species therein may be regarded as unaltered. Under reducing conditions, subsurface water is always saturated with uranium. Whether water interacts with rock or uranium ore, the equilibrium uranium concentration in water is only ≤10-8 mol/l. Uraninite ore under such conditions always remains stable irrespective of its age. The stability conditions of uranium ore are quite suitable for safe insulation of SNF, which consists of 95% uraninite (UO2) and is a confinement matrix for all other radionuclides. The disposal of SNF in massifs of crystalline rocks at depths below 500 m, where reducing conditions are predominant, is a reliable guarantee of high SNF stability. Under oxidizing conditions of the upper hydrodynamic zone, the rate of interaction of rocks with subsurface water increases by orders of magnitude and subsurface water is commonly undersaturated with uranium. Uranium absorbed by secondary minerals, particularly by iron hydroxides and leucoxene, is its single stable species under oxidizing conditions. The impact of oxygen-bearing water leads to destruction of uranium ore. This process is realized simultaneously at different hypsometric levels even if the permeability of the medium is variable in both the lateral and vertical directions. As a result, intervals containing uranyl minerals and relics of primary uranium ore are combined in ore-bearing zones with intervals of completely dissolved uranium minerals. A wide halo of elevated uranium contents caused by sorption is always retained at the location of uranium ore entirely destroyed by weathering. Uranium ore commonly finds itself in the aeration zone due to technogenic subsidence of the groundwater table caused by open-pit mining or pumping out of water from underground mines. The capillary and film waters that interact with rocks and ores in this zone are supplemented by free water filtering along fractures when rain falls or snow is thawing. The interaction of uranium ore with capillary water results in oxidation of uraninite, accompanied by loosening of the mineral surface, formation of microfractures, and an increase in solubility with enrichment of capillary water in uranium up to 10-4 mol/l. Secondary U(VI) minerals, first of all, uranyl hydroxides and silicates, replace uraninite, and uranium undergoes local diffusion redistribution with its sorption by secondary minerals of host rocks. The influx of free water facilitates the complete dissolution of primary and secondary uranium minerals, the removal of uranium at the sites of groundwater discharge, and its redeposition under reducing conditions at a greater depth. It is evident that the conditions of the upper hydrodynamic zone and the aeration zone are unfit for long-term insulation of SNF and high-level wastes because, after the failure of containers, the leakage of radionuclides into the environment becomes inevitable.

Characterization and modes of occurrence of elements in feed coal and coal combustion products from a power plant utilizing low-sulfur coal from the Powder River Basin, Wyoming

USGS Publications Warehouse

Brownfield, Michael E.; Cathcart, James D.; Affolter, Ronald H.; Brownfield, Isabelle K.; Rice, Cynthia A.; O'Connor, Joseph T.; Zielinski, Robert A.; Bullock, John H.; Hower, James C.; Meeker, Gregory P.

2005-01-01

The U.S. Geological Survey and the University of Kentucky Center for Applied Energy Research are collaborating with an Indiana utility company to determine the physical and chemical properties of feed coal and coal combustion products from a coal-fired power plant. The Indiana power plant utilizes a low-sulfur (0.23 to 0.47 weight percent S) and lowash (4.9 to 6.3 weight percent ash) subbituminous coal from the Wyodak-Anderson coal zone in the Tongue River Member of the Paleocene Fort Union Formation, Powder River Basin, Wyoming. Based on scanning electron microscope and X-ray diffraction analyses of feed coal samples, two mineral suites were identified: (1) a primary or detrital suite consisting of quartz (including beta-form grains), biotite, feldspar, and minor zircon; and (2) a secondary authigenic mineral suite containing alumino-phosphates (crandallite and gorceixite), kaolinite, carbonates (calcite and dolomite), quartz, anatase, barite, and pyrite. The primary mineral suite is interpreted, in part, to be of volcanic origin, whereas the authigenic mineral suite is interpreted, in part, to be the result of the alteration of the volcanic minerals. The mineral suites have contributed to the higher amounts of barium, calcium, magnesium, phosphorus, sodium, strontium, and titanium in the Powder River Basin feed coals in comparison to eastern coals. X-ray diffraction analysis indicates that (1) fly ash is mostly aluminate glass, perovskite, lime, gehlenite, quartz, and phosphates with minor amounts of periclase, anhydrite, hematite, and spinel group minerals; and (2) bottom ash is predominantly quartz, plagioclase (albite and anorthite), pyroxene (augite and fassaite), rhodonite, and akermanite, and spinel group minerals. Microprobe and scanning electron microscope analyses of fly ash samples revealed quartz, zircon, and monazite, euhedral laths of corundum with merrillite, hematite, dendritic spinels/ferrites, wollastonite, and periclase. The abundant calcium and magnesium mineral phases in the fly ash are attributed to the presence of carbonate, clay, and phosphate minerals in the feed coal and their alteration to new phases during combustion. The amorphous diffraction-scattering maxima or glass 'hump' appears to reflect differences in chemical composition of fly ash and bottom ash glasses. In Wyodak-Anderson fly and bottom ashes, the center point of scattering maxima is due to calcium and magnesium content, whereas the glass 'hump' of eastern fly ash reflects variation in aluminum content. The calcium- and magnesium-rich and alumino-phosphate mineral phases in the coal combustion products can be attributed to volcanic minerals deposited in peat-forming mires. Dissolution and alteration of these detrital volcanic minerals occurred either in the peat-forming stage or during coalification and diagenesis, resulting in the authigenic mineral suite. The presence of free lime (CaO) in fly ash produced from Wyodak-Anderson coal acts as a self-contained 'scrubber' for SO3, where CaO + SO3 form anhydrite either during combustion or in the upper parts of the boiler. Considering the high lime content in the fly ash and the resulting hydration reactions after its contact with water, there is little evidence that major amounts of leachable metals are mobilized in the disposal or utilization of this fly ash.

Composites of gellan gum hydrogel enzymatically mineralized with calcium-zinc phosphate for bone regeneration with antibacterial activity.

PubMed

Douglas, Timothy E L; Pilarz, Magdalena; Lopez-Heredia, Marco; Brackman, Gilles; Schaubroeck, David; Balcaen, Lieve; Bliznuk, Vitaliy; Dubruel, Peter; Knabe-Ducheyne, Christine; Vanhaecke, Frank; Coenye, Tom; Pamula, Elzbieta

2017-05-01

Gellan gum hydrogels functionalized with alkaline phosphatase were enzymatically mineralized with phosphates in mineralization medium containing calcium (Ca) and zinc (Zn) to improve their suitability as biomaterials for bone regeneration. The aims of the study were to endow mineralized hydrogels with antibacterial activity by incorporation of Zn in the inorganic phase, and to investigate the effect of Zn incorporation on the amount and type of mineral formed, the compressive modulus of the mineralized hydrogels and on their ability to support adhesion and growth of MC3T3-E1 osteoblast-like cells. Mineralization medium contained glycerophosphate (0.05 m) and three different molar Ca:Zn ratios, 0.05:0, 0.04:0.01 and 0.025:0.025 (all mol/dm 3 ), hereafter referred to as A, B and C, respectively. FTIR, SAED and TEM analysis revealed that incubation for 14 days caused the formation of predominantly amorphous mineral phases in sample groups A, B and C. The presence of Zn in sample groups B and C was associated with a drop in the amount of mineral formed and a smaller mineral deposit morphology, as observed by SEM. ICP-OES revealed that Zn was preferentially incorporated into mineral compared to Ca. Mechanical testing revealed a decrease in compressive modulus in sample group C. Sample groups B and C, but not A, showed antibacterial activity against biofilm-forming, methicillin-resistant Staphylococcus aureus. All sample groups supported cell growth. Zn incorporation increased the viable cell number. The highest values were seen on sample group C. In conclusion, the sample group containing the most Zn, i.e. group C, appears to be the most promising. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Study of Some Mineral Exchangers for Use in Water at High Temperature; ETUDE DE QUELQUES ECHANGEURS MINERAUX UTILISABLES DANS L'EAU A HAUTE TEMPERATURE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hure, J.; Platzer, R.; Bittel, R.

1959-10-31

The study of the use of ion exchangers at high temperatures was made with a view to the purification of water in reactors. Natural ion exchangers with mineral structures (clay of the montmorillonite type), natural mineral compounds so treated as to give them the properties of ion exchangers (activated graphite), and synthetic mineral compounds (zirconium phosphates and hydroxides and thorium hydroxide) were investigated. The preparation of the minerals is described, and the results obtained with them are discussed in detail. (J.S.R.)

Structure-Composition-Property Relationships in Polymeric Amorphous Calcium Phosphate-Based Dental Composites †

PubMed Central

O’Donnell, Justin N.R.; Schumacher, Gary E.; Antonucci, Joseph M.; Skrtic, Drago

2009-01-01

Our studies of amorphous calcium phosphate (ACP)-based materials over the last decade have yielded bioactive polymeric composites capable of protecting teeth from demineralization or even regenerating lost tooth mineral. The anti-cariogenic/re-mineralizing potential of these ACP composites originates from their propensity, when exposed to the oral environment, to release in a sustained manner sufficient levels of mineral-forming calcium and phosphate ions to promote formation of stable apatitic tooth mineral. However, the less than optimal ACP filler/resin matrix cohesion, excessive polymerization shrinkage and water sorption of these experimental materials can adversely affect their physicochemical and mechanical properties, and, ultimately, limit their lifespan. This study demonstrates the effects of chemical structure and composition of the methacrylate monomers used to form the matrix phase of composites on degree of vinyl conversion (DVC) and water sorption of both copolymers and composites and the release of mineral ions from the composites. Modification of ACP surface via introducing cations and/or polymers ab initio during filler synthesis failed to yield mechanically improved composites. However, moderate improvement in composite’s mechanical stability without compromising its remineralization potential was achieved by silanization and/or milling of ACP filler. Using ethoxylated bisphenol A dimethacrylate or urethane dimethacrylate as base monomers and adding moderate amounts of hydrophilic 2-hydroxyethyl methacrylate or its isomer ethyl-α-hydroxymethacrylate appears to be a promising route to maximize the remineralizing ability of the filler while maintaining high DVC. Exploration of the structure/composition/property relationships of ACP fillers and polymer matrices is complex but essential for achieving a better understanding of the fundamental mechanisms that govern dissolution/re-precipitation of bioactive ACP fillers, and, ultimately, the suitability of the composites for clinical evaluation. PMID:21966588

CENTENNIAL MOUNTAINS WILDERNESS STUDY AREA, MONTANA AND IDAHO.

USGS Publications Warehouse

Witkind, Irving J.; Ridenour, James

1984-01-01

A mineral survey conducted within the Centennial Mountains Wilderness study area in Montana and Idaho showed large areas of probable and substantiated resource potential for phosphate. Byproducts that may be derived from processing the phosphate include vanadium, chromium, uranium, silver, fluorine, and the rare earths, lanthanum and yttrium. Results of a geochemical sampling program suggest that there is little promise for the occurrence of base and precious metals in the area. Although the area contains other nonmetallic deposits, such as coal, building stone, and pumiceous ash they are not considered as mineral resources. There is a probable resource potential for oil and gas and significant amounts may underlie the area around the Peet Creek and Odell Creek anticlines.

Effects of three phosphate industrial sites on ground-water quality in central Florida, 1979 to 1980

USGS Publications Warehouse

Miller, R.L.; Sutcliffe, Horace

1984-01-01

Geologic, hydrologic, and water quality data and information on test holes collected in the vicinity of gypsum stack complexes at two phosphate chemical plants and one phosphatic clayey waste disposal pond at a phosphate mine and beneficiation plant in central Florida are presented. The data were collected from September 1979 to October 1980 at the AMAX Phosphate, Inc. chemical plant, Piney Point; the USS Agri-Chemicals chemical plant, Bartow; and the International Minerals and Chemical Corporation Clear Springs mine, Bartow. Approximately 5,400 field and laboratory water quality determinations on water samples collected from about 100 test holes and 28 surface-water , 5 rainfall, and other sampling sites at phosphate industry beneficiation and chemical plant waste disposal operations are tabulated. Maps are included to show sampling sites. (USGS)

Water-quality and hydrogeologic data for three phosphate industry waste-disposal sites in central Florida, 1979-80

USGS Publications Warehouse

Miller, Ronald L.; Sutcliffe, Horace

1982-01-01

This report is a complilation of geologic, hydrologic, and water-quality data and information on test holes collected in the vicinity of gypsum stack complexes at two phosphate chemical plants and one phosphatic clayey waste disposal pond at a phosphate mine and beneficiation plant in central Florida. The data were collected from September 1979 to October 1980 at thee AMAX Phosphate, Inc., chemical plant, Piney Point; the USS AgriChemicals chemical plant, Bartow; and the International Minerals and Chemical Corporation Clear Springs mine, Bartow. Approximmmtely 5,400 field and laboratory water-quality determinations on water samples were collected from about 78 test holes and 31 surface-water, rainfall, and other sampling sites at phosphate industry beneficiation and chemical plant waste-disposal operations. Maps show locations of sampling sites. (USGS)

AN INVESTIGATION OF THE MINERAL IN DUCTILE AND BRITTLE CORTICAL MOUSE BONE

PubMed Central

Rodriguez-Florez, Naiara; Garcia-Tunon, Esther; Mukadam, Quresh; Saiz, Eduardo; Oldknow, Karla J.; Farquharson, Colin; Millán, José Luis; Boyde, Alan; Shefelbine, Sandra J.

2015-01-01

Bone is a strong and tough material composed of apatite mineral, organic matter and water. Changes in composition and organization of these building blocks affect bone’s mechanical integrity. Skeletal disorders often affect bone’s mineral phase, either by variations in the collagen or directly altering mineralization. The aim of the current study was to explore the differences in the mineral of brittle and ductile cortical bone at the mineral (nm) and tissue (µm) levels using two mouse phenotypes. Osteogenesis imperfecta murine (oim−/−) mice were used to model brittle bone; PHOSPHO1 mutants (Phospho1−/−) had ductile bone. They were compared to their respective wild-type controls. Femora were defatted and ground to powder to measure average mineral crystal size using X-ray diffraction (XRD), and to monitor the bulk mineral to matrix ratio via thermogravimetric analysis (TGA). XRD scans were run after TGA for phase identification, to assess the fractions of hydroxyapatite and β-tricalcium phosphate. Tibiae were embedded to measure elastic properties with nanoindentation and the extent of mineralization with backscattered electron microscopy (qbSEM). Interestingly, the mineral of brittle oim−/− and ductile Phospho1−/− bones had many similar characteristics. Both pathology models had smaller apatite crystals, lower mineral to matrix ratio, and showed more thermal conversion to β-tricalcium phosphate than their wild-types, indicating deviations from stoichiometric hydroxyapatite in the original mineral. The degree of mineralization of the bone matrix was different for each strain: oim−/− were hypermineralized, while Phospho1−/− were hypomineralized. However, alterations in the mineral were associated with reduced tissue elastic moduli in both pathologies. Results revealed that despite having extremely different whole bone mechanics, the mineral of oim−/− and Phospho1−/− has several similar trends at smaller length scales. This indicates that alterations from normal crystal size, composition, and structure will reduce the mechanical integrity of bone. PMID:25418329

Margaritasite: a new mineral of hydrothermal origin from the Pena Blanca uranium district, Mexico.

USGS Publications Warehouse

Wenrich, K.J.; Modreski, P.J.; Zielinski, R.A.; Seeley, J.L.

1982-01-01

Margaritasite, (Cs,K,H3O)2(UO2)2V2O8.nH2O (where Cs > K, H3O and n approx 1), a 10.514, b 8.425, c 7.25 A, beta 106.01o, P21/a, Z = 2, is a newly recognized uranium ore mineral named for the Margaritas deposit, Pena Blanca uranium district, Chihuahua, Mexico, at which it was discovered. A Cs-rich analogue of carnotite, margaritasite is the natural equivalent of synthetic Cs-uranyl vanadate (A.M. 43- 799, 50-825). A fine-grained yellow mineral, it is most easily distinguished from carnotite by XRD; X-ray powder patterns (CuKalpha radiation) show that the (001) reflection of margaritasite lies at 12.7o (2theta ), while that of carnotite is found at 13.8o (2theta ). The shift of the (001) reflection in margaritasite reflects the structural changes caused when Cs occupies the sites filled by K in carnotite. Synthesis experiments indicate that margaritasite also differs from carnotite in a higher-T hydrothermal origin. Chemical analyses and XRD data for margaritasite and synthetic Cs- carnotite, and chemical analyses for rocks from Sierra Pena Blanca and vicinity, are tabulated.-J.A.Z.

Uranium speciation as a function of depth in contaminated hanford sediments--a micro-XRF, micro-XRD, and micro- and bulk-XAFS study.

PubMed

Singer, David M; Zachara, John M; Brown, Gordon E

2009-02-01

The distribution and speciation of U and Cu in contaminated vadose zone and aquifer sediments from the U.S. DOE Hanford site (300 Area) were determined using a combination of synchrotron-based micro-X-ray fluorescence (microXRF) imaging, micro-X-ray absorption near edge structure (microXANES) spectroscopy, and micro-X-ray diffraction (microXRD) techniques combined with bulk U LIII-edge X-ray absorption fine structure (XAFS) spectroscopy. Samples were collected from within the inactive North Process Pond (NPP2) at 8 ft (2.4 m, NPP2-8) depth and 12 ft (3.7 m, NPP2-12) depth in the vadose zone, and fines were isolated from turbid groundwater just below the water Table (12-14 ft, approximately 4 m, NPP2-GW). microXRF imaging, microXRD, and microXANES spectroscopy revealed two major U occurrences within the vadose and groundwater zones: (1) low to moderate concentrations of U(VI) associated with fine-textured grain coatings that were consistently found to contain clinochlore (referred to here as chlorite) observed in all three samples, and (2) U(VI)-Cu(II) hotspots consisting of micrometer-sized particles associated with surface coatings on grains of muscovite and chlorite observed in samples NPP2-8' and NPP2-GW. In the aquifer fines (NPP2-GW), these particles were identified as cuprosklodowskite (cps: Cu[(UO2)(SiO2OH)]2 x 6H2O) and metatorbernite (mtb: Cu(UO2)2(PO4)2 x 8H2O). In contrast, the U-Cu-containing particles in the vadose zone were X-ray amorphous. Analyses of U LIII-edge XAFS spectra by linear-combination fitting indicated that U speciation consisted of (1) approximately 75% uranyl sorbed to chlorite and approximately 25% mtb-like X-ray amorphous U-Cu-phosphates (8 ft depth), (2) nearly 100% sorbed uranyl (12 ft depth), and (3) approximately 70% uranyl sorbed to chlorite and approximately 30% cps/mtb (groundwater zone). These findings suggest that dissolution of U(VI)-Cu(II)-bearing solids as well as desorption of U(VI), mainly from phyllosilicates, are important persistent sources of U(VI) to the associated uranium groundwater plume in Hanford Area 300.

How do arbuscular mycorrhizal fungi handle phosphate? New insight into fine-tuning of phosphate metabolism.

PubMed

Ezawa, Tatsuhiro; Saito, Katsuharu

2018-04-27

Contents Summary I. Introduction II. Foraging for phosphate III. Fine-tuning of phosphate homeostasis IV. The frontiers: phosphate translocation and export V. Conclusions and outlook Acknowledgements References SUMMARY: Arbuscular mycorrhizal fungi form symbiotic associations with most land plants and deliver mineral nutrients, in particular phosphate, to the host. Therefore, understanding the mechanisms of phosphate acquisition and delivery in the fungi is critical for full appreciation of the mutualism in this association. Here, we provide updates on physical, chemical, and biological strategies of the fungi for phosphate acquisition, including interactions with phosphate-solubilizing bacteria, and those on the regulatory mechanisms of phosphate homeostasis based on resurveys of published genome sequences and a transcriptome with reference to the latest findings in a model fungus. For the mechanisms underlying phosphate translocation and export to the host, which are major research frontiers in this field, not only recent advances but also testable hypotheses are proposed. Lastly, we briefly discuss applicability of the latest tools to gene silencing in the fungi, which will be breakthrough techniques for comprehensive understanding of the molecular basis of fungal phosphate metabolism. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

High phosphate feeding promotes mineral and bone abnormalities in mice with chronic kidney disease.

PubMed

Lau, Wei Ling; Linnes, Michael; Chu, Emily Y; Foster, Brian L; Bartley, Bryan A; Somerman, Martha J; Giachelli, Cecilia M

2013-01-01

Chronic kidney disease-mineral bone disorder (CKD-MBD) is a systemic syndrome characterized by imbalances in mineral homeostasis, renal osteodystrophy (ROD) and ectopic calcification. The mechanisms underlying this syndrome in individuals with chronic kidney disease (CKD) are not yet clear. We examined the effect of normal phosphate (NP) or high phosphate (HP) feeding in the setting of CKD on bone pathology, serum biochemistry and vascular calcification in calcification-prone dilute brown non-agouti (DBA/2) mice. In both NP and HP-fed CKD mice, elevated serum parathyroid hormone and alkaline phosphatase (ALP) levels were observed, but serum phosphorus levels were equivalent compared with sham controls. CKD mice on NP diet showed trabecular alterations in the long bone consistent with high-turnover ROD, including increased trabecular number with abundant osteoblasts and osteoclasts. Despite trabecular bone and serum biochemical changes, CKD/NP mice did not develop vascular calcification. In contrast, CKD/HP mice developed arterial medial calcification (AMC), more severe trabecular bone alterations and cortical bone abnormalities that included decreased cortical thickness and density, and increased cortical porosity. Cortical bone porosity and trabecular number strongly correlated with the degree of aortic calcification. HP feeding was required to induce the full spectrum of CKD-MBD symptoms in CKD mice.

Minerals in the gut: scoping a Cambrian digestive system

NASA Astrophysics Data System (ADS)

Strang, K. M.; Armstrong, H. A.; Harper, D. A. T.

2016-11-01

The Sirius Passet Lagerstätte of North Greenland contains the first exceptionally preserved mat-ground community of the Cambrian, dominated, in terms of abundance, by trilobites but particularly characterized by iconic arthropods and lobopods, some also occurring in the Burgess shale. High-resolution photography, scanning electron imaging and elemental mapping have been carried out on a variety of specimens of the non-mineralized arthropod Campanamuta mantonae (Budd 2011 J. Syst. Palaeontol. 9, 217-260 (doi:10.1080/14772019.2010.492644)) which has three-dimensional gut and muscle preservation. Results show that the guts contain a high concentration of calcium phosphate (approximating to the mineral francolite), whereas the adjacent muscles are silicified. This indicates a unique, tissue-specific taphonomy for this Cambrian taxon. We hypothesize that the precipitation of calcium phosphate in the guts occurs rapidly after death by `crystal seed' processes in suboxic, slightly acidic conditions; critically, the gut wall remained intact during precipitation. We postulate that the calcium phosphate was derived from ingested cellular material. Silicification of the muscles followed as the localized water chemistry became saturated in silica, high in Fe2+, and low in oxygen and sulfate. We document here the unique occurrence of two distinct but mechanistically similar taphonomic pathways within a diverse suite of possibilities in an Early Cambrian Lagerstätte.

Uranyl peroxide enhanced nuclear fuel corrosion in seawater.

PubMed

Armstrong, Christopher R; Nyman, May; Shvareva, Tatiana; Sigmon, Ginger E; Burns, Peter C; Navrotsky, Alexandra

2012-02-07

The Fukushima-Daiichi nuclear accident brought together compromised irradiated fuel and large amounts of seawater in a high radiation field. Based on newly acquired thermochemical data for a series of uranyl peroxide compounds containing charge-balancing alkali cations, here we show that nanoscale cage clusters containing as many as 60 uranyl ions, bonded through peroxide and hydroxide bridges, are likely to form in solution or as precipitates under such conditions. These species will enhance the corrosion of the damaged fuel and, being thermodynamically stable and kinetically persistent in the absence of peroxide, they can potentially transport uranium over long distances.

M4FT-15OR03100415 - Update on COF-based Adsorbent Survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayes, Richard T.; Dai, Sheng

2015-02-01

This letter report provides an update on activities focused on generating nanoporous adsorbents involving covalent organic frameworks (COF) and zeolitic imidazolium frameworks (ZIF). The adsorbents have been generated and screened in a uranyl-spiked brine (6 ppm U) to understand uranyl-binding behavior. Porous organic polymers (POP) also qualify under this title and are similar to the COF PPN-6 that is discussed herein. Seven COF/POP and one 1 ZIF were synthesized and screened for uranyl adsorption. Seawater screening is on-going via batch testing while flow screening systems are being developed at PNNL.

Method for loading resin beds

DOEpatents

Notz, Karl J.; Rainey, Robert H.; Greene, Charles W.; Shockley, William E.

1978-01-01

An improved method of preparing nuclear reactor fuel by carbonizing a uranium loaded cation exchange resin provided by contacting a H.sup.+ loaded resin with a uranyl nitrate solution deficient in nitrate, comprises providing the nitrate deficient solution by a method comprising the steps of reacting in a reaction zone maintained between about 145.degree.-200.degree. C, a first aqueous component comprising a uranyl nitrate solution having a boiling point of at least 145.degree. C with a second aqueous component to provide a gaseous phase containing HNO.sub.3 and a reaction product comprising an aqueous uranyl nitrate solution deficient in nitrate.

Uranyl peroxide enhanced nuclear fuel corrosion in seawater

PubMed Central

Armstrong, Christopher R.; Nyman, May; Shvareva, Tatiana; Sigmon, Ginger E.; Burns, Peter C.; Navrotsky, Alexandra

2012-01-01

The Fukushima-Daiichi nuclear accident brought together compromised irradiated fuel and large amounts of seawater in a high radiation field. Based on newly acquired thermochemical data for a series of uranyl peroxide compounds containing charge-balancing alkali cations, here we show that nanoscale cage clusters containing as many as 60 uranyl ions, bonded through peroxide and hydroxide bridges, are likely to form in solution or as precipitates under such conditions. These species will enhance the corrosion of the damaged fuel and, being thermodynamically stable and kinetically persistent in the absence of peroxide, they can potentially transport uranium over long distances. PMID:22308442

Octacalcium phosphate: osteoconductivity and crystal chemistry.

PubMed

Suzuki, O

2010-09-01

Octacalcium phosphate (OCP), which is structurally similar to hydroxyapatite (HA), is a possible precursor of bone apatite crystals. Although disagreement remains as to whether OCP comprises the initial mineral crystals in the early stage of bone mineralization, the results of recent biomaterial studies using synthetic OCP indicate the potential role of OCP as a bone substitute material, owing to its highly osteoconductive and biodegradable characteristics. OCP tends to convert to HA not only in an in vitro environment, but also as an implant in bone defects. Several lines of evidence from both in vivo and in vitro studies suggest that the conversion process could be involved in the stimulatory capacity of OCP for osteoblastic differentiation and osteoclast formation. However, the osteoconductivity of OCP cannot always be secured if an OCP with distinct crystal characteristics is used, because the stoichiometry and microstructure of OCP crystals greatly affect bone-regenerative properties. Osteoconductivity and stimulatory capabilities may be caused by the chemical characteristics of OCP, which allows the release or exchange of calcium and phosphate ions with the surrounding of this salt, and its tendency to grow towards specific crystal faces, which could be a variable of the synthesis condition. This paper reviews the effect of calcium phosphates on osteoblastic activity and bone regeneration, with a special emphasis on OCP, since OCP seems to be performing better than other calcium phosphates in vivo. 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Phosphate and phytate adsorption and precipitation on ferrihydrite surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Xiaoming; Hu, Yongfeng; Tang, Yadong

Phosphorous (P) sorption on mineral surfaces largely controls P mobility and bioavailability, hence its pollution potential, but the sorption speciation and mechanism remain poorly understood. In this study, we have identified and quantified the speciation of both phosphate and phytate sorbed on ferrihydrite with various P loadings at pH 3–8 using differential atomic pair distribution function (d-PDF) analysis, synchrotron-based X-ray diffraction (XRD), and P and Fe K-edge X-ray absorption near edge structure (XANES) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. With increasing P sorption loading for both phosphate and phytate, the sorption mechanism transits from bidentate-binuclear surface complexation tomore » unidentified ternary complexation and to precipitation of amorphous FePO 4 and amorphous Fe-phytate. At a given P sorption loading, phosphate precipitates more readily than phytate. Both phosphate and phytate promote ferrihydrite dissolution with phytate more intensively, but the dissolved FeIII concentration in the bulk solution is low because the majority of the released Fe III precipitate with the anions. Results also show that amorphous FePO 4 and amorphous Fe-phytate have similar PO 4 local coordination environment. In conclusion, these new insights into the P surface complexation and precipitation, and the ligand-promoted dissolution behavior improve our understanding of P fate in soils, aquatic environment and water treatment systems as mediated by mineral-water interfacial reactions.« less

Phosphate and phytate adsorption and precipitation on ferrihydrite surfaces

DOE PAGES

Wang, Xiaoming; Hu, Yongfeng; Tang, Yadong; ...

2017-09-26

Phosphorous (P) sorption on mineral surfaces largely controls P mobility and bioavailability, hence its pollution potential, but the sorption speciation and mechanism remain poorly understood. In this study, we have identified and quantified the speciation of both phosphate and phytate sorbed on ferrihydrite with various P loadings at pH 3–8 using differential atomic pair distribution function (d-PDF) analysis, synchrotron-based X-ray diffraction (XRD), and P and Fe K-edge X-ray absorption near edge structure (XANES) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. With increasing P sorption loading for both phosphate and phytate, the sorption mechanism transits from bidentate-binuclear surface complexation tomore » unidentified ternary complexation and to precipitation of amorphous FePO 4 and amorphous Fe-phytate. At a given P sorption loading, phosphate precipitates more readily than phytate. Both phosphate and phytate promote ferrihydrite dissolution with phytate more intensively, but the dissolved FeIII concentration in the bulk solution is low because the majority of the released Fe III precipitate with the anions. Results also show that amorphous FePO 4 and amorphous Fe-phytate have similar PO 4 local coordination environment. In conclusion, these new insights into the P surface complexation and precipitation, and the ligand-promoted dissolution behavior improve our understanding of P fate in soils, aquatic environment and water treatment systems as mediated by mineral-water interfacial reactions.« less

Prevention of bone mineral changes induced by bed rest: Modification by static compression simulating weight bearing, combined supplementation of oral calcium and phosphate, calcitonin injections, oscillating compression, the oral diophosphonatedisodium etidronate, and lower body negative pressure

NASA Technical Reports Server (NTRS)

Schneider, V. S.; Hulley, S. B.; Donaldson, C. L.; Vogel, J. M.; Rosen, S. N.; Hantman, D. A.; Lockwood, D. R.; Seid, D.; Hyatt, K. H.; Jacobson, L. B.

1974-01-01

The phenomenon of calcium loss during bed rest was found to be analogous to the loss of bone material which occurs in the hypogravic environment of space flight. Ways of preventing this occurrence are investigated. A group of healthy adult males underwent 24-30 weeks of continuous bed rest. Some of them were given an exercise program designed to resemble normal ambulatory activity; another subgroup was fed supplemental potassium phosphate. The results from a 12-week period of treatment were compared with those untreated bed rest periods. The potassium phosphate supplements prevented the hypercalciuria of bed rest, but fecal calcium tended to increase. The exercise program did not diminish the negative calcium balance. Neither treatment affected the heavy loss of mineral from the calcaneus. Several additional studies are developed to examine the problem further.

A vibrational spectroscopic study of the phosphate mineral vantasselite Al4(PO4)3(OH)3·9H2O

NASA Astrophysics Data System (ADS)

Frost, Ray L.; Scholz, Ricardo; Belotti, Fernanda Maria; López, Andrés; Theiss, Frederick L.

2015-08-01

We have studied the phosphate mineral vantasselite Al4(PO4)3(OH)3·9H2O using a combination of SEM with EDX and Raman and infrared spectroscopy. Qualitative chemical analysis shows Al, Fe and P. Raman bands at 1013 and 1027 cm-1 are assigned to the PO43- ν1 symmetric stretching mode. The observation of two bands suggests the non-equivalence of the phosphate units in the vantasselite structure. Raman bands at 1051, 1076 and 1090 cm-1 are attributed to the PO43- ν3 antisymmetric stretching vibration. A comparison is made with the spectroscopy of wardite. Strong infrared bands at 1044, 1078, 1092, 1112, 1133, 1180 and 1210 cm-1 are attributed to the PO43- ν3 antisymmetric stretching mode. Some of these bands may be due to δAl2OH deformation modes. Vibrational spectroscopy offers a mechanism for the study of the molecular structure of vantasselite.

Biomimetic remineralization of dentin

PubMed Central

Niu, Li-na; Zhang, Wei; Pashley, David H.; Breschi, Lorenzo; Mao, Jing; Chen, Ji-hua; Tay, Franklin R.

2013-01-01

Objectives Remineralization of demineralized dentin is important for improving dentin bonding stability and controlling primary and secondary caries. Nevertheless, conventional dentin remineralization strategy is not suitable for remineralizing completely-demineralized dentin within hybrid layers created by etch-and-rinse and moderately aggressive self-etch adhesive systems, or the superficial part of a caries-affected dentin lesion left behind after minimally invasive caries removal. Biomimetic remineralization represents a different approach to this problem by attempting to backfill the demineralized dentin collagen with liquid-like amorphous calcium phosphate nanoprecursor particles that are stabilized by biomimetic analogs of noncollagenous proteins. Methods This paper reviewed the changing concepts in calcium phosphate mineralization of fibrillar collagen, including the recently discovered, non-classical particle-based crystallization concept, formation of polymer-induced liquid- precursors (PILP), experimental collagen models for mineralization, and the need for using phosphate-containing biomimetic analogs for biomimetic mineralization of collagen. Published work on the remineralization of resin-dentin bonds and artificial caries-like lesions by various research groups was then reviewed. Finally, the problems and progress associated with the translation of a scientifically-sound concept into a clinically-applicable approach are discussed. Results and Significance The particle-based biomimetic remineralization strategy based on the PILP process demonstrates great potential in remineralizing faulty hybrid layers or caries-like dentin. Based on this concept, research in the development of more clinically feasible dentin remineralization strategy, such as incorporating poly(anionic) acid-stabilized amorphous calcium phosphate nanoprecursor-containing mesoporous silica nanofillers in dentin adhesives, may provide a promising strategy for increasing of the durability of resin-dentin bonding and remineralizing caries-affected dentin. PMID:23927881

Weathering Profiles in Phosphorus-Rich Rocks at Gusev Crater, Mars, Suggest Dissolution of Phosphate Minerals into Potentially Habitable Near-Neutral Waters.

PubMed

Adcock, Christopher T; Hausrath, Elisabeth M

2015-12-01

Abundant evidence indicates that significant surface and near-surface liquid water has existed on Mars in the past. Evaluating the potential for habitable environments on Mars requires an understanding of the chemical and physical conditions that prevailed in such aqueous environments. Among the geological features that may hold evidence of past environmental conditions on Mars are weathering profiles, such as those in the phosphorus-rich Wishstone-class rocks in Gusev Crater. The weathering profiles in these rocks indicate that a Ca-phosphate mineral has been lost during past aqueous interactions. The high phosphorus content of these rocks and potential release of phosphorus during aqueous interactions also make them of astrobiological interest, as phosphorus is among the elements required for all known life. In this work, we used Mars mission data, laboratory-derived kinetic and thermodynamic data, and data from terrestrial analogues, including phosphorus-rich basalts from Idaho, to model a conceptualized Wishstone-class rock using the reactive transport code CrunchFlow. Modeling results most consistent with the weathering profiles in Wishstone-class rocks suggest a combination of chemical and physical erosion and past aqueous interactions with near-neutral waters. The modeling results also indicate that multiple Ca-phosphate minerals are likely in Wishstone-class rocks, consistent with observations of martian meteorites. These findings suggest that Gusev Crater experienced a near-neutral phosphate-bearing aqueous environment that may have been conducive to life on Mars in the past. Mars-Gusev Crater-Wishstone-Reactive transport modeling-CrunchFlow-Aqueous interactions-Neutral pH-Habitability.

The interrelationship of microstructure and hardness of human coronal dentin using reference point indentation technique and micro-Raman spectroscopy.

PubMed

Seyedmahmoud, Rasoul; McGuire, Jacob D; Wang, Yong; Thiagarajan, Ganesh; Walker, Mary P

2017-10-01

The aim of this paper is to determine the interrelationship between the microstructure - in terms of chemical composition and crystallinity - to the microhardness of coronal dentin. Dentin microhardness was tested by a novel reference point indenter and compared to the traditional Knoop hardness method. Micro-Raman spectroscopy was used to determine the chemical composition and crystallinity of dentin. From the occlusal groove to the border of the coronal pulp chamber, dentin hardness decreased from superficial dentin (SD) to deep dentin (DD). Mineral/organic matrix ratios (phosphate/CH and phosphate/amide I) also decreased from SD to DD; however, this change was significant (P<0.05) in the phosphate/amide I ratio only. The phosphate/carbonate ratio decreased significantly by varying position from SD to DD. The degree of the crystallinity, as measured by the full width at half maximum (FWHM) of the peak at 960cm -1 , decreased significantly going from superficial to deep dentin. For the first time, the interrelationship between the microstructure and the mechanical properties of coronal dentin was determined by using the novel reference point indentation technique and micro-Raman spectroscopy. We hypothesize that the decrease in hardness from superficial to deep dentin can potentially be explained by decreased mineral content and increased carbonate content, which is also associated with decreased crystallinity. Collectively, there is a positive association between dentin hardness and mineral content and a negative association between dentin hardness and carbonate content. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Nanoscale Confinement Controls the Crystallization of Calcium Phosphate: Relevance to Bone Formation

PubMed Central

Cantaert, Bram; Beniash, Elia; Meldrum, Fiona C.

2015-01-01

A key feature of biomineralization processes is that they take place within confined volumes, in which the local environment can have significant effects on mineral formation. Herein, we investigate the influence of confinement on the formation mechanism and structure of calcium phosphate (CaP). This is of particular relevance to the formation of dentine and bone, structures of which are based on highly mineralized collagen fibrils. CaP was precipitated within 25–300 nm diameter, cylindrical pores of track etched and anodised alumina membranes under physiological conditions, in which this system enables systematic study of the effects of the pore size in the absence of a structural match between the matrix and the growing crystals. Our results show that the main products were polycrystalline hydroxapatite (HAP) rods, together with some single crystal octacalcium phosphate (OCP) rods. Notably, we demonstrate that these were generated though an intermediate amorphous calcium phosphate (ACP) phase, and that ACP is significantly stabilised in confinement. This effect may have significance to the mineralization of bone, which can occur through a transient ACP phase. We also show that orientation of the HAP comparable, or even superior to that seen in bone can be achieved through confinement effects alone. Although this simple experimental system cannot be considered, a direct mimic of the in vivo formation of ultrathin HAP platelets within collagen fibrils, our results show that the effects of physical confinement should not be neglected when considering the mechanisms of formation of structures, such as bones and teeth. PMID:24115275

Nanoscale confinement controls the crystallization of calcium phosphate: relevance to bone formation.

PubMed

Cantaert, Bram; Beniash, Elia; Meldrum, Fiona C

2013-10-25

A key feature of biomineralization processes is that they take place within confined volumes, in which the local environment can have significant effects on mineral formation. Herein, we investigate the influence of confinement on the formation mechanism and structure of calcium phosphate (CaP). This is of particular relevance to the formation of dentine and bone, structures of which are based on highly mineralized collagen fibrils. CaP was precipitated within 25-300 nm diameter, cylindrical pores of track etched and anodised alumina membranes under physiological conditions, in which this system enables systematic study of the effects of the pore size in the absence of a structural match between the matrix and the growing crystals. Our results show that the main products were polycrystalline hydroxapatite (HAP) rods, together with some single crystal octacalcium phosphate (OCP) rods. Notably, we demonstrate that these were generated though an intermediate amorphous calcium phosphate (ACP) phase, and that ACP is significantly stabilised in confinement. This effect may have significance to the mineralization of bone, which can occur through a transient ACP phase. We also show that orientation of the HAP comparable, or even superior to that seen in bone can be achieved through confinement effects alone. Although this simple experimental system cannot be considered, a direct mimic of the in vivo formation of ultrathin HAP platelets within collagen fibrils, our results show that the effects of physical confinement should not be neglected when considering the mechanisms of formation of structures, such as bones and teeth. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Conterminous United States Mineral Assessment Program; background information to accompany folio of geologic, geochemical, remote sensing, and mineral resources maps of the Butte 1 degree x 2 degrees Quadrangle, Montana

USGS Publications Warehouse

Elliott, James E.; Trautwein, C.M.; Wallace, C.A.; Lee, G.K.; Rowan, L.C.; Hanna, W.F.

1993-01-01

The Butte 1?x2 ? quadrangle in west-central Montana was investigated as part of the U.S. Geological Survey's Conterminous United States Mineral Assessment Program (CUSMAP). These investigations included geologic mapping, geochemical surveys, gravity and aeromagnetic surveys, examinations of mineral deposits, and specialized geochronologic and remote-sensing studies. The data collected during these studies were compiled, combined with available published and unpublished data, analyzed, and used in a mineral-resource assessment of the quadrangle. The results, including data, interpretations, and mineral-resource assessments for nine types of mineral deposits, are published separately as a folio of maps. These maps are accompanied by figures, tables, and explanatory text. This circular provides background information on the Butte quadrangle, summarizes the studies and published maps, and lists a selected bibliography of references pertinent to the geology, geochemistry, geophysics, and mineral resources of the quadrangle. The Butte quadrangle, which includes the world-famous Butte mining district, has a long history of mineral production. Many mining districts within the quadrangle have produced large quantities of many commodities; the most important in dollar value of production were copper, gold, silver, lead, zinc, manganese, molybdenum, and phosphate. At present, mines at several locations produce copper, molybdenum, gold, silver, lead, zinc, and phosphate. Exploration, mainly for gold, has indicated the presence of other mineral deposits that may be exploited in the future. The results of the investigations by the U.S. Geological Survey indicate that many areas of the quadrangle are highly favorable for the occurrence of additional undiscovered resources of gold, silver, copper, molybdenum, tungsten, and other metals in several deposit types.

The role of extracellular DNA in uranium precipitation and biomineralisation.

PubMed

Hufton, Joseph; Harding, John H; Romero-González, Maria E

2016-10-26

Bacterial extra polymeric substances (EPS) have been associated with the extracellular precipitation of uranium. Here we report findings on the biomineralisation of uranium, with extracellular DNA (eDNA) used as a model biomolecule representative of EPS. The complexation and precipitation of eDNA with uranium were investigated as a function of pH, ionic strength and varying concentrations of reactants. The role of phosphate moieties in the biomineralisation mechanism was studied by enzymatically releasing phosphate (ePO 4 ) from eDNA compared to abiotic phosphate (aPO 4 ). The eDNA-uranium precipitates and uranium minerals obtained were characterised by Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FT-IR) spectroscopy, Scanning Electron Microscopy-Energy Dispersive X-Ray analysis (SEM-EDX), X-Ray Powder Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS). ATR-FT-IR showed that at pH 5, the eDNA-uranium precipitation mechanism was predominantly mediated by interactions with phosphate moieties from eDNA. At pH 2, the uranium interactions with eDNA occur mainly through phosphate. The solubility equilibrium was dependent on pH with the formation of precipitate reduced as the pH increased. The XRD data confirmed the formation of a uranium phosphate precipitate when synthesised using ePO 4 . XPS and SEM-EDX studies showed the incorporation of carbon and nitrogen groups from the enzymatic orthophosphate hydrolysis on the obtained precipitated. These results suggested that the removal of uranium from solution occurs via two mechanisms: complexation by eDNA molecules and precipitation of a uranium phosphate mineral of the type (UO 2 HPO 4 )·xH 2 O by enzymatic orthophosphate hydrolysis. This demonstrated that eDNA from bacterial EPS is a key contributor to uranium biomineralisation.

Effect of early nutritional intake on long-term growth and bone mineralization of former very low birth weight infants.

PubMed

Christmann, V; van der Putten, M E; Rodwell, L; Steiner, K; Gotthardt, M; van Goudoever, J B; van Heijst, A F J

2018-03-01

Preterm infants are at risk for impaired bone mineralization and growth in length later in life due to inadequate nutritional intake in the early postnatal period. To investigate whether increased nutritional supplementation of calcium, phosphate and protein in Very Low Birth Weight (VLBW) infants during the first 14days after birth was associated with improvement in length and bone development until 9-10years of age. Observational follow-up study of VLBW infants (birth weight<1500g or gestational age<32weeks) born in two consecutive years (eligible infants: 2004 n: 63 and 2005: n: 66). Cohort 2005 received higher intake of calcium, phosphate and protein with parenteral nutrition compared to Cohort 2004. Anthropometric data were collected during standard follow-up visits until five years, and additionally at 9-10years of age including measurements of bone mineral content, bone mineral density of the whole body and lumbar spine determined by dual-energy X-ray absorptiometry. Long-term growth trajectories of both cohorts were evaluated separately for participants born appropriate (AGA) and small for gestational age (SGA), stratified by gender. Multivariate linear regression was used to examine the effect of nutritional intake and clinical covariates on length and bone mineralization. Both cohorts achieved a catch-up in length to SDS within the normal range by 6months (length SDS: estimated mean (95% confidence interval (CI): 6months: Cohort 2004: -0.7 (-1.1, -0.3) Cohort 2005: -0.5 (-0.8, -0.2)). Bone mineral content and density were within the normal range and not different between the cohorts. SGA children achieved a catch-up in length at 5years with bone mineralization comparable to AGA children. Only for girls birth weight was significantly associated with length SDS (per gram: β 0.001; 95% CI (0.000, 0.003); p=0.03) There was no evidence of an association between early nutritional intake and bone mineralization. Children born as appropriate or small for gestational age preterm infants are able to catch up in length after the postnatal period, and achieve a normal length and bone mineralization at age nine-ten years. An improvement of calcium and phosphate intake during the first 14days after birth was not associated with improvement in length and bone development. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Influence of uranyl speciation and iron oxides on uranium biogeochemical redox reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stewart, B.D.; Amos, R.T.; Nico, P.S.

2010-03-15

Uranium is a pollutant of concern to both human and ecosystem health. Uranium's redox state often dictates its partitioning between the aqueous- and solid-phases, and thus controls its dissolved concentration and, coupled with groundwater flow, its migration within the environment. In anaerobic environments, the more oxidized and mobile form of uranium (UO{sub 2}{sup 2+} and associated species) may be reduced, directly or indirectly, by microorganisms to U(IV) with subsequent precipitation of UO{sub 2}. However, various factors within soils and sediments may limit biological reduction of U(VI), inclusive of alterations in U(VI) speciation and competitive electron acceptors. Here we elucidate themore » impact of U(VI) speciation on the extent and rate of reduction with specific emphasis on speciation changes induced by dissolved Ca, and we examine the impact of Fe(III) (hydr)oxides (ferrihydrite, goethite and hematite) varying in free energies of formation on U reduction. The amount of uranium removed from solution during 100 h of incubation with S. putrefaciens was 77% with no Ca or ferrihydrite present but only 24% (with ferrihydrite) and 14% (no ferrihydrite) were removed for systems with 0.8 mM Ca. Imparting an important criterion on uranium reduction, goethite and hematite decrease the dissolved concentration of calcium through adsorption and thus tend to diminish the effect of calcium on uranium reduction. Dissimilatory reduction of Fe(III) and U(VI) can proceed through different enzyme pathways, even within a single organism, thus providing a potential second means by which Fe(III) bearing minerals may impact U(VI) reduction. We quantify rate coefficients for simultaneous dissimilatory reduction of Fe(III) and U(VI) in systems varying in Ca concentration (0 to 0.8 mM), and using a mathematical construct implemented with the reactive transport code MIN3P, we reveal the predominant influence of uranyl speciation, specifically the formation of uranyl-calcium-carbonato complexes, and ferrihydrite on the rate and extent of uranium reduction in complex geochemical systems.« less

Incorporation of oxidized uranium into Fe (hydr)oxides during Fe(II) catalyzed remineralization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nico, Peter S.; Stewart, Brandy D.; Fendorf, Scott

2009-07-01

The form of solid phase U after Fe(II) induced anaerobic remineralization of ferrihydrite in the presence of aqueous and absorbed U(VI) was investigated under both abiotic batch and biotic flow conditions. Experiments were conducted with synthetic ground waters containing 0.168 mM U(VI), 3.8 mM carbonate, and 3.0 mM Ca{sup 2+}. In spite of the high solubility of U(VI) under these conditions, appreciable removal of U(VI) from solution was observed in both the abiotic and biotic systems. The majority of the removed U was determined to be substituted as oxidized U (U(VI) or U(V)) into the octahedral position of the goethitemore » and magnetite formed during ferrihydrite remineralization. It is estimated that between 3% and 6% of octahedral Fe(III) centers in the new Fe minerals were occupied by U(VI). This site specific substitution is distinct from the non-specific U co-precipitation processes in which uranyl compounds, e.g. uranyl hydroxide or carbonate, are entrapped with newly formed Fe oxides. The prevalence of site specific U incorporation under both abiotic and biotic conditions and the fact that the produced solids were shown to be resistant to both extraction (30 mM KHCO{sub 3}) and oxidation (air for 5 days) suggest the potential importance of sequestration in Fe oxides as a stable and immobile form of U in the environment.« less

Sensitive life detection strategies for low-biomass environments: optimizing extraction of nucleic acids adsorbing to terrestrial and Mars analogue minerals.

PubMed

Direito, Susana O L; Marees, Andries; Röling, Wilfred F M

2012-07-01

The adsorption of nucleic acids to mineral matrixes can result in low extraction yields and negatively influences molecular microbial ecology studies, in particular for low-biomass environments on Earth and Mars. We determined the recovery of nucleic acids from a range of minerals relevant to Earth and Mars. Clay minerals, but also other silicates and nonsilicates, showed very low recovery (< 1%). Consequently, optimization of DNA extraction was directed towards clays. The high temperatures and acidic conditions used in some methods to dissolve mineral matrices proved to destruct DNA. The most efficient method comprised a high phosphate solution (P/EtOH; 1 M phosphate, 15% ethanol buffer at pH 8) introduced at the cell-lysing step in DNA extraction, to promote chemical competition with DNA for adsorption sites. This solution increased DNA yield from clay samples spiked with known quantities of cells up to nearly 100-fold. DNA recovery was also enhanced from several mineral samples retrieved from an aquifer, while maintaining reproducible DGGE profiles. DGGE profiles were obtained for a clay sample for which no profile could be generated with the standard DNA isolation protocol. Mineralogy influenced microbial community composition. The method also proved suitable for the recovery of low molecular weight DNA (< 1.5 kb). © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Microbially induced selective flotation of sphalerite from galena using mineral-adapted strains of Bacillus megaterium.

PubMed

Vasanthakumar, B; Ravishankar, H; Subramanian, S

2013-12-01

The selective flotation of sphalerite from a sphalerite-galena mineral mixture has been achieved using cells and extracellular secretions of Bacillus megaterium after adaptation to the chosen minerals. The extracellular secretions obtained after thermolysis of bacterial cells adapted to sphalerite yield the highest flotation recovery of sphalerite with a selectivity index value of 24.5, in comparison to the other cellular and extra-cellular bio-reagents studied. The protein profile for the unadapted and mineral-adapted cells has been found to differ distinctly, attesting to variation in the yield and nature of extra-cellular polymeric substances (EPS). The changes induced in the bacterial cell wall components after adaptation to sphalerite or galena with respect to the contents of phosphate, uronic acid and acetylated sugars of B. megaterium have been quantified. The role of the dissolved metal ions from the minerals as well as that of the constituents of extracellular secretions in modulating the surface charge of the bacterial cells as well as the minerals under study has been confirmed using various enzymatic treatments of the bacterial cells. It has been demonstrated that the induction of additional molecular weight protein fractions as well as the higher amount of extracellular proteins and phosphate secreted after adaptation to sphalerite vis-à-vis galena are contributory factors for the selective separation of sphalerite from galena. Copyright © 2013 Elsevier B.V. All rights reserved.

Anomalous REE patterns in unequilibrated enstatite chondrites: Evidence and implications

NASA Technical Reports Server (NTRS)

Crozaz, Ghislaine; Hsu, Weibiao

1993-01-01

We present here a study of Rare Earth Element (REE) microdistributions in unequilibrated enstatite chondrites (EOC's). Although the whole rock REE contents are similar in both unequilibrated and equilibrated chondrites, the host minerals of these refractory elements are different. In the least equilibrated ordinary chondrites (UOC's), the REE reside mainly in glass whereas, in their more equilibrated counterparts, the bulk of the REE is in calcium phosphate, a metamorphic mineral that formed by oxidation of phosphorous originally contained in metal. In the smaller group of enstatite (E) chondrites, calcium phosphate is absent and the phase that contains the highest REE concentrations is a minor mineral, CaS (oldhamite), which contains approximately 50 percent of the total Ca present. In E chondrites, elements typically considered to be lithophiles (such as Ca and Mn) occur in sulfides rather than silicates. This indicates formation under extremely reducing conditions, thus in a region of the solar nebula distinct from those that supplied the more abundant ordinary and carbonaceous chondrites. Previously, we observed a variety of REE patterns in the oldhamite of UEC's; they range from almost flat to some with pronounced positive Eu and Yb anomalies. Here, we searched for complementary REE patterns in other minerals from E chondrites and found them in the major mineral, enstatite. Whenever Eu and Yb anomalies are present in this mineral, they are always negative.

Highly Sensitive and Selective Uranium Detection in Natural Water Systems Using a Luminescent Mesoporous Metal-Organic Framework Equipped with Abundant Lewis Basic Sites: A Combined Batch, X-ray Absorption Spectroscopy, and First Principles Simulation Investigation.

PubMed

Liu, Wei; Dai, Xing; Bai, Zhuanling; Wang, Yanlong; Yang, Zaixing; Zhang, Linjuan; Xu, Lin; Chen, Lanhua; Li, Yuxiang; Gui, Daxiang; Diwu, Juan; Wang, Jianqiang; Zhou, Ruhong; Chai, Zhifang; Wang, Shuao

2017-04-04

Uranium is not only a strategic resource for the nuclear industry but also a global contaminant with high toxicity. Although several strategies have been established for detecting uranyl ions in water, searching for new uranium sensor material with great sensitivity, selectivity, and stability remains a challenge. We introduce here a hydrolytically stable mesoporous terbium(III)-based MOF material compound 1, whose channels are as large as 27 Å × 23 Å and are equipped with abundant exposed Lewis basic sites, the luminescence intensity of which can be efficiently and selectively quenched by uranyl ions. The detection limit in deionized water reaches 0.9 μg/L, far below the maximum contamination standard of 30 μg/L in drinking water defined by the United States Environmental Protection Agency, making compound 1 currently the only MOF material that can achieve this goal. More importantly, this material exhibits great capability in detecting uranyl ions in natural water systems such as lake water and seawater with pH being adjusted to 4, where huge excesses of competing ions are present. The uranyl detection limits in Dushu Lake water and in seawater were calculated to be 14.0 and 3.5 μg/L, respectively. This great detection capability originates from the selective binding of uranyl ions onto the Lewis basic sites of the MOF material, as demonstrated by synchrotron radiation extended X-ray adsorption fine structure, X-ray adsorption near edge structure, and first principles calculations, further leading to an effective energy transfer between the uranyl ions and the MOF skeleton.

Crystal Chemistry of the Potassium and Rubidium Uranyl Borate Families Derived from Boric Acid Fluxes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Shuao; Alekseev, Evgeny V.; Stritzinger, Jared T.

2010-07-19

The reaction of uranyl nitrate with a large excess of molten boric acid in the presence of potassium or rubidium nitrate results in the formation of three new potassium uranyl borates, K{sub 2}[(UO{sub 2}){sub 2}B{sub 12}O{sub 19}(OH){sub 4}]·0.3H{sub 2}O (KUBO-1), K[(UO{sub 2}){sub 2}B{sub 10}O{sub 15}(OH){sub 5}] (KUBO-2), and K[(UO{sub 2}){sub 2}B{sub 10}O{sub 16}(OH){sub 3}]·0.7H{sub 2}O (KUBO-3) and two new rubidium uranyl borates Rb{sub 2}[(UO{sub 2}){sub 2}B{sub 13}O{sub 20}(OH){sub 5}] (RbUBO-1) and Rb[(UO{sub 2}){sub 2}B{sub 10}O{sub 16}(OH){sub 3}]·0.7H{sub 2}O (RbUBO-2). The latter is isotypic with KUBO-3. These compounds share a common structural motif consisting of a linear uranyl, UO{sub 2}{sup 2+},more » cation surrounded by BO{sub 3} triangles and BO{sub 4} tetrahedra to create an UO{sub 8} hexagonal bipyramidal environment around uranium. The borate anions bridge between uranyl units to create sheets. Additional BO{sub 3} triangles extend from the polyborate layers and are directed approximately perpendicular to the sheets. All of these compounds adopt layered structures. With the exception of KUBO-1, the structures are all centrosymmetric. All of these compounds fluoresce when irradiated with long-wavelength UV light. The fluorescence spectrum yields well-defined vibronically coupled charge-transfer features.« less

Zooplankton fecal pellets link fossil fuel and phosphate deposits

USGS Publications Warehouse

Porter, K.G.; Robbins, E.I.

1981-01-01

Fossil zooplankton fecal pellets found in thinly bedded marine and lacustrine black shales associated with phosphate, oil, and coal deposits, link the deposition of organic matter and biologically associated minerals with planktonic ecosystems. The black shales were probably formed in the anoxic basins of coastal marine waters, inland seas, and rift valley lakes where high productivity was supported by runoff, upwelling, and outwelling. Copyright ?? 1981 AAAS.

Long-term treatment with tenofovir in Asian-American chronic hepatitis B patients is associated with abnormal renal phosphate handling.

PubMed

Tien, Connie; Xu, Jason J; Chan, Linda S; Chang, Mimi; Lim, Carolina; Lee, Sue; Huh, Brian; Shinada, Shuntaro; Bae, Ho S; Fong, Tse-Ling

2015-02-01

Increased risk of defective urinary phosphate reabsorption and osteoporosis has been reported in HIV and chronic hepatitis B (CHB) patients treated with tenofovir disoproxil fumarate (TDF). Goals of this study were to evaluate the prevalence of renal phosphate wasting and abnormal bone mineral density in CHB patients taking TDF compared to CHB patients treated with entecavir (ETV) and untreated CHB patients. This is a cross-sectional study of 146 consecutive Asian-American CHB patients who were treatment naïve (n = 60) or treated with either TDF (n = 42) or ETV (n = 44). Proximal tubular handling of phosphate was assessed by the maximal rate of tubular reabsorption of phosphate (TmPO4) divided by glomerular filtration rate (GFR) (TmPO4/GFR). Bone mineral density (BMD) was measured using dual X-ray absorptiometry. TmPO4/GFR was similar among CHB patients treated with TDF compared to untreated patients and patients taking ETV. However, among patients treated with ≥18 months of TDF or ETV, prevalence of abnormal TmPO4/GFR was higher among patients treated with TDF compared to ETV (48.5 % (16/33) vs. 12.5 % (3/24), p = 0.005). Overall prevalence of osteoporosis in this cohort of CHB patients was 14 %, with no significant difference between the three groups. Renal phosphate handling did not correlate with osteoporosis. Chronic hepatitis B patients treated with ≥18 months of TDF experienced an increased risk of proximal tubular dysfunction. TDF did not increase the risk of osteoporosis. Longitudinal studies are needed to confirm these findings.

Kinetics of apatite formation on a calcium-silicate cement for root-end filling during ageing in physiological-like phosphate solutions.

PubMed

Gandolfi, Maria Giovanna; Taddei, Paola; Tinti, Anna; De Stefano Dorigo, Elettra; Rossi, Piermaria Luigi; Prati, Carlo

2010-12-01

The bioactivity of calcium silicate mineral trioxide aggregate (MTA) cements has been attributed to their ability to produce apatite in presence of phosphate-containing fluids. This study evaluated surface morphology and chemical transformations of an experimental accelerated calcium-silicate cement as a function of soaking time in different phosphate-containing solutions. Cement discs were immersed in Dulbecco's phosphate-buffered saline (DPBS) or Hank's balanced salt solution (HBSS) for different times (1-180 days) and analysed by scanning electron microscopy connected with an energy dispersive X-ray analysis (SEM-EDX) and micro-Raman spectroscopy. SEM-EDX revealed Ca and P peaks after 14 days in DPBS. A thin Ca- and P-rich crystalline coating layer was detected after 60 days. A thicker multilayered coating was observed after 180 days. Micro-Raman disclosed the 965-cm(-1) phosphate band at 7 days only on samples stored in DPBS and later the 590- and 435-cm(-1) phosphate bands. After 60-180 days, a layer approximately 200-900 μm thick formed displaying the bands of carbonated apatite (at 1,077, 965, 590, 435 cm(-1)) and calcite (at 1,088, 713, 280 cm(-1)). On HBSS-soaked, only calcite bands were observed until 90 days, and just after 180 days, a thin apatite-calcite layer appeared. Micro-Raman and SEM-EDX demonstrated the mineralization induction capacity of calcium-silicate cements (MTAs and Portland cements) with the formation of apatite after 7 days in DPBS. Longer time is necessary to observe bioactivity when cements are immersed in HBSS.

Nectar minerals as regulators of flower visitation in stingless bees and nectar hoarding wasps.

PubMed

Afik, Ohad; Delaplane, Keith S; Shafir, Sharoni; Moo-Valle, Humberto; Quezada-Euán, J Javier G

2014-05-01

Various nectar components have a repellent effect on flower visitors, and their adaptive advantages for the plant are not well understood. Persea americana (avocado) is an example of a plant that secretes nectar with repellent components. It was demonstrated that the mineral constituents of this nectar, mainly potassium and phosphate, are concentrated enough to repel honey bees, Apis mellifera, a pollinator often used for commercial avocado pollination. Honey bees, however, are not the natural pollinator of P. americana, a plant native to Central America. In order to understand the role of nectar minerals in plant-pollinator relationships, it is important to focus on the plant's interactions with its natural pollinators. Two species of stingless bees and one species of social wasp, all native to the Yucatan Peninsula, Mexico, part of the natural range of P. americana, were tested for their sensitivity to sugar solutions enriched with potassium and phosphate, and compared with the sensitivity of honey bees. In choice tests between control and mineral-enriched solutions, all three native species were indifferent for mineral concentrations lower than those naturally occurring in P. americana nectar. Repellence was expressed at concentrations near or exceeding natural concentrations. The threshold point at which native pollinators showed repellence to increasing levels of minerals was higher than that detected for honey bees. The results do not support the hypothesis that high mineral content is attractive for native Hymenopteran pollinators; nevertheless, nectar mineral composition may still have a role in regulating flower visitors through different levels of repellency.

Insight into hydrogen bonding of uranyl hydroxide layers and capsules by use of 1H magic-angle spinning NMR spectroscopy [Insight into the hydrogen bonding for uranyl hydroxides using 1H MAS NMR spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alam, Todd M.; Liao, Zuolei; Nyman, May

Solid-state 1H magic-angle spinning (MAS) NMR was used to investigate local proton environments in anhydrous [UO 2(OH) 2] (α-UOH) and hydrated uranyl hydroxide [(UO 2) 4O(OH) 6·5H 2O (metaschoepite). For the metaschoepite material, proton resonances of the μ 2-OH hydroxyl and interlayer waters were resolved, with two-dimensional (2D) double-quantum (DQ) 1H– 1H NMR correlation experiments revealing strong dipolar interactions between these different proton species. The experimental NMR results were combined with first-principles CASTEP GIPAW (gauge including projector-augmented wave) chemical shift calculations to develop correlations between hydrogen-bond strength and observed 1H NMR chemical shifts. Furthermore, these NMR correlations allowed characterization ofmore » local hydrogen-bond environments in uranyl U 24 capsules and of changes in hydrogen bonding that occurred during thermal dehydration of metaschoepite.« less

Sorption of uranium in uranyl nitrate solutions on strong cationic resins and its elution with ammonium sulfate. II. Effects of EDTA on thorium decontamination; Estudos de sorpcao de uranio contido em solucoes de nitrato de uranilo por resina cationica forte e sua eluicao com sulfato de amonio. Parte II: efeito de EDTA na descontaminacao do torio (in Portuguese)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ribas, Antonio G.S.; Abrao, Alcidio

1970-05-15

This paper describes the studies of decontamination of thorium present as impurity in uranyl nitrate solutions, which was carried out through strong cationic resin where the thorium was partially retained. Then, the final decontamination was performed percolating the uranyl solution on a second cationic resin, after complexation of thorium (and other impurities) with EDTA. The thorium decontamination and the uranium retention were studied as a function of EDTA/U ratio, uranium concentration and acidity of the influent uranyl nitrate. The elution conditions were also studied as a function of eluent flow rate, concentration and acidity. Several tables and graphs showing themore » final results are included. (tr-auth)« less

Synthesis and characterization of new ion-imprinted polymer for separation and preconcentration of uranyl (UO2(2+)) ions.

PubMed

Ahmadi, Seyed Javad; Noori-Kalkhoran, Omid; Shirvani-Arani, Simindokht

2010-03-15

UO(2)(2+) ion-imprinted polymer materials used for solid-phase extraction were prepared by copolymerization of a ternary complex of uranyl ions with styrene and divinyl benzene in the presence of 2,2'-azobisisobutyronitrile. The imprinted particles were leached by HCl 6M. Various parameters in polymerization steps such as DVB/STY ratio, time of polymerization and temperature of polymerization were varied to achieve the most efficient uranyl-imprinted polymer. X-ray diffraction (XRD), infra-red spectroscopy (IR), thermo gravimetric analysis (TGA), UV-vis and nitrogen sorption were used to characterize the polymer particles. The XRD results showed that uranyl ions were completely removed from the polymer after leaching process. IR Analysis indicated that the N,N'-ethylenebis(pyridoxylideneiminato) remained intact in the polymer even after leaching. Some parameters such as pH, weight of the polymer, elution time, eluent volume and aqueous phase volume which affects the efficiency of the polymer were studied. (c) 2009 Elsevier B.V. All rights reserved.

Predicting Stability Constants for Uranyl Complexes Using Density Functional Theory

DOE PAGES

Vukovic, Sinisa; Hay, Benjamin P.; Bryantsev, Vyacheslav S.

2015-04-02

The ability to predict the equilibrium constants for the formation of 1:1 uranyl:ligand complexes (log K 1 values) provides the essential foundation for the rational design of ligands with enhanced uranyl affinity and selectivity. We also use density functional theory (B3LYP) and the IEFPCM continuum solvation model to compute aqueous stability constants for UO 2 2+ complexes with 18 donor ligands. Theoretical calculations permit reasonably good estimates of relative binding strengths, while the absolute log K 1 values are significantly overestimated. Accurate predictions of the absolute log K 1 values (root mean square deviation from experiment < 1.0 for logmore » K 1 values ranging from 0 to 16.8) can be obtained by fitting the experimental data for two groups of mono and divalent negative oxygen donor ligands. The utility of correlations is demonstrated for amidoxime and imide dioxime ligands, providing a useful means of screening for new ligands with strong chelate capability to uranyl.« less

Insight into hydrogen bonding of uranyl hydroxide layers and capsules by use of 1H magic-angle spinning NMR spectroscopy [Insight into the hydrogen bonding for uranyl hydroxides using 1H MAS NMR spectroscopy

DOE PAGES

Alam, Todd M.; Liao, Zuolei; Nyman, May; ...

2016-04-27

Solid-state 1H magic-angle spinning (MAS) NMR was used to investigate local proton environments in anhydrous [UO 2(OH) 2] (α-UOH) and hydrated uranyl hydroxide [(UO 2) 4O(OH) 6·5H 2O (metaschoepite). For the metaschoepite material, proton resonances of the μ 2-OH hydroxyl and interlayer waters were resolved, with two-dimensional (2D) double-quantum (DQ) 1H– 1H NMR correlation experiments revealing strong dipolar interactions between these different proton species. The experimental NMR results were combined with first-principles CASTEP GIPAW (gauge including projector-augmented wave) chemical shift calculations to develop correlations between hydrogen-bond strength and observed 1H NMR chemical shifts. Furthermore, these NMR correlations allowed characterization ofmore » local hydrogen-bond environments in uranyl U 24 capsules and of changes in hydrogen bonding that occurred during thermal dehydration of metaschoepite.« less

Uranium XAFS analysis of kidney from rats exposed to uranium

PubMed Central

Kitahara, Keisuke; Numako, Chiya; Terada, Yasuko; Nitta, Kiyohumi; Homma-Takeda, Shino

2017-01-01

The kidney is the critical target of uranium exposure because uranium accumulates in the proximal tubules and causes tubular damage, but the chemical nature of uranium in kidney, such as its chemical status in the toxic target site, is poorly understood. Micro-X-ray absorption fine-structure (µXAFS) analysis was used to examine renal thin sections of rats exposed to uranyl acetate. The U L III-edge X-ray absorption near-edge structure spectra of bulk renal specimens obtained at various toxicological phases were similar to that of uranyl acetate: their edge position did not shift compared with that of uranyl acetate (17.175 keV) although the peak widths for some kidney specimens were slightly narrowed. µXAFS measurements of spots of concentrated uranium in the micro-regions of the proximal tubules showed that the edge jump slightly shifted to lower energy. The results suggest that most uranium accumulated in kidney was uranium (VI) but a portion might have been biotransformed in rats exposed to uranyl acetate. PMID:28244440

Uranium XAFS analysis of kidney from rats exposed to uranium.

PubMed

Kitahara, Keisuke; Numako, Chiya; Terada, Yasuko; Nitta, Kiyohumi; Shimada, Yoshiya; Homma-Takeda, Shino

2017-03-01

The kidney is the critical target of uranium exposure because uranium accumulates in the proximal tubules and causes tubular damage, but the chemical nature of uranium in kidney, such as its chemical status in the toxic target site, is poorly understood. Micro-X-ray absorption fine-structure (µXAFS) analysis was used to examine renal thin sections of rats exposed to uranyl acetate. The U L III -edge X-ray absorption near-edge structure spectra of bulk renal specimens obtained at various toxicological phases were similar to that of uranyl acetate: their edge position did not shift compared with that of uranyl acetate (17.175 keV) although the peak widths for some kidney specimens were slightly narrowed. µXAFS measurements of spots of concentrated uranium in the micro-regions of the proximal tubules showed that the edge jump slightly shifted to lower energy. The results suggest that most uranium accumulated in kidney was uranium (VI) but a portion might have been biotransformed in rats exposed to uranyl acetate.

Enhanced cellular preservation by clay minerals in 1 billion-year-old lakes.

PubMed

Wacey, David; Saunders, Martin; Roberts, Malcolm; Menon, Sarath; Green, Leonard; Kong, Charlie; Culwick, Timothy; Strother, Paul; Brasier, Martin D

2014-07-28

Organic-walled microfossils provide the best insights into the composition and evolution of the biosphere through the first 80 percent of Earth history. The mechanism of microfossil preservation affects the quality of biological information retained and informs understanding of early Earth palaeo-environments. We here show that 1 billion-year-old microfossils from the non-marine Torridon Group are remarkably preserved by a combination of clay minerals and phosphate, with clay minerals providing the highest fidelity of preservation. Fe-rich clay mostly occurs in narrow zones in contact with cellular material and is interpreted as an early microbially-mediated phase enclosing and replacing the most labile biological material. K-rich clay occurs within and exterior to cell envelopes, forming where the supply of Fe had been exhausted. Clay minerals inter-finger with calcium phosphate that co-precipitated with the clays in the sub-oxic zone of the lake sediments. This type of preservation was favoured in sulfate-poor environments where Fe-silicate precipitation could outcompete Fe-sulfide formation. This work shows that clay minerals can provide an exceptionally high fidelity of microfossil preservation and extends the known geological range of this fossilization style by almost 500 Ma. It also suggests that the best-preserved microfossils of this time may be found in low-sulfate environments.

Enhanced cellular preservation by clay minerals in 1 billion-year-old lakes

PubMed Central

Wacey, David; Saunders, Martin; Roberts, Malcolm; Menon, Sarath; Green, Leonard; Kong, Charlie; Culwick, Timothy; Strother, Paul; Brasier, Martin D.

2014-01-01

Organic-walled microfossils provide the best insights into the composition and evolution of the biosphere through the first 80 percent of Earth history. The mechanism of microfossil preservation affects the quality of biological information retained and informs understanding of early Earth palaeo-environments. We here show that 1 billion-year-old microfossils from the non-marine Torridon Group are remarkably preserved by a combination of clay minerals and phosphate, with clay minerals providing the highest fidelity of preservation. Fe-rich clay mostly occurs in narrow zones in contact with cellular material and is interpreted as an early microbially-mediated phase enclosing and replacing the most labile biological material. K-rich clay occurs within and exterior to cell envelopes, forming where the supply of Fe had been exhausted. Clay minerals inter-finger with calcium phosphate that co-precipitated with the clays in the sub-oxic zone of the lake sediments. This type of preservation was favoured in sulfate-poor environments where Fe-silicate precipitation could outcompete Fe-sulfide formation. This work shows that clay minerals can provide an exceptionally high fidelity of microfossil preservation and extends the known geological range of this fossilization style by almost 500 Ma. It also suggests that the best-preserved microfossils of this time may be found in low-sulfate environments. PMID:25068404

Structural optimization and amorphous calcium phosphate mineralization in sensory setae of a terrestrial crustacean (Isopoda: Oniscidea).

PubMed

Vittori, Miloš; Srot, Vesna; Bussmann, Birgit; Predel, Felicitas; van Aken, Peter A; Štrus, Jasna

2018-06-09

Terrestrial isopods possess large sensory setae on their walking legs. Increased fracture resistance of these elongated structures is of crucial importance, making the exoskeleton forming the setae an interesting durable material that may inspire biomimetic designs. We studied the cuticle of the sensory setae with analytical electron microscopy in order to gain detailed insights into its structure and composition at the nanometer scale and identify features that increase the fracture resistance of these minute skeletal elements. The setae are stiff structures formed by mineralized cuticle that are connected to the leg exoskeleton by a non-mineralized joint membrane. Our results demonstrate that different layers of the setal cuticle display contrasting organizations of the chitin-protein fibers and mineral particles. While in the externally positioned exocuticle organic fibers shift their orientation helicoidally in sequential layers, the fibers are aligned axially in the internally positioned endocuticle. In the setal cuticle, layers of structurally anisotropic cuticle likely providing strength in the axial direction are combined with layers of isotropic cuticle which may allow the setae to better resist perpendicular loading. They are further strengthened with amorphous calcium phosphate, a highly fracture resistant mineral rarely observed in invertebrate skeletons. Copyright © 2018 Elsevier Ltd. All rights reserved.

Vibrational spectroscopy of the phosphate mineral kovdorskite - Mg2PO4(OH)ṡ3H2O

NASA Astrophysics Data System (ADS)

Frost, Ray L.; López, Andrés; Xi, Yunfei; Granja, Amanda; Scholz, Ricardo; Lima, Rosa Malena Fernandes

2013-10-01

The mineral kovdorskite Mg2PO4(OH)ṡ3H2O was studied by electron microscopy, thermal analysis and vibrational spectroscopy. A comparison of the vibrational spectroscopy of kovdorskite is made with other magnesium bearing phosphate minerals and compounds. Electron probe analysis proves the mineral is very pure. The Raman spectrum is characterized by a band at 965 cm-1 attributed to the PO43- ν1 symmetric stretching mode. Raman bands at 1057 and 1089 cm-1 are attributed to the PO43- ν3 antisymmetric stretching modes. Raman bands at 412, 454 and 485 cm-1 are assigned to the PO43- ν2 bending modes. Raman bands at 536, 546 and 574 cm-1 are assigned to the PO43- ν4 bending modes. The Raman spectrum in the OH stretching region is dominated by a very sharp intense band at 3681 cm-1 assigned to the stretching vibration of OH units. Infrared bands observed at 2762, 2977, 3204, 3275 and 3394 cm-1 are attributed to water stretching bands. Vibrational spectroscopy shows that no carbonate bands are observed in the spectra; thus confirming the formula of the mineral as Mg2PO4(OH)ṡ3H2O.

Calcium Bioavailability from Mineral Waters with Different Mineralization in Comparison to Milk and a Supplement.

PubMed

Greupner, Theresa; Schneider, Inga; Hahn, Andreas

2017-07-01

The aim of the present study was to compare the bioavailability of calcium from 3 mineral waters with different concentrations of minerals with that of milk and a calcium supplement. A single-center, randomized controlled trial with a crossover design with 21 healthy men and women was conducted at the Institute of Food Science and Human Nutrition, Leibniz University Hannover. The participants consumed the 5 test products providing 300 mg of calcium each on 5 examination days with 1-week wash-out phases in between. Primary outcome variables were the area under the curve of serum calcium levels for 10-hour (AUC 0-10h ) and 24-hour urinary calcium excretion. In all groups, no significant differences in the AUC 0-10h of serum calcium levels as well as in the 24-hour urinary calcium excretion were observed. Likewise, mean changes in serum phosphate and urinary phosphate, as well as serum parathormone, showed no differences between the groups. Given an equivalent bioavailability of calcium in all test products, neither a high concentration of SO 4 2- or of HCO 3 influenced the bioavailability of calcium. Accordingly, the use of mineral water with high concentrations of calcium constitutes a calorie-free calcium source that can improve calcium supply.

Nucleation of hydroxyapatite by bone sialoprotein.

PubMed Central

Hunter, G K; Goldberg, H A

1993-01-01

Bone sialoprotein (BSP) and osteopontin, the major phosphorylated proteins of mammalian bone, have been proposed to function in the initiation of mineralization. To test this hypothesis, the effects of BSP and osteopontin on hydroxyapatite crystal formation were determined by using a steady-state agarose gel system. At low calcium phosphate concentrations, no accumulation of calcium and phosphate occurred in control gels or gels containing osteopontin. Gels containing BSP at 1-5 micrograms/ml, however, exhibited a visible precipitation band and significantly elevated Ca + PO4 contents. By powder x-ray diffraction, the precipitate formed in the presence of BSP was shown to be hydroxyapatite. These findings suggest that bone sialoprotein may be involved in the nucleation of hydroxyapatite at the mineralization front of bone. Images Fig. 4 PMID:8397409

Uranyl coordination in ionic liquids: the competition between ionic liquid anions, uranyl counterions, and Cl- anions investigated by extended X-ray absorption fine structure and UV-visible spectroscopies and molecular dynamics simulations.

PubMed

Gaillard, C; Chaumont, A; Billard, I; Hennig, C; Ouadi, A; Wipff, G

2007-06-11

The first coordination sphere of the uranyl cation in room-temperature ionic liquids (ILs) results from the competition between its initially bound counterions, the IL anions, and other anions (e.g., present as impurities or added to the solution). We present a joined spectroscopic (UV-visible and extended X-ray absorption fine structure)-simulation study of the coordination of uranyl initially introduced either as UO2X2 salts (X-=nitrate NO3-, triflate TfO-, perchlorate ClO4-) or as UO2(SO4) in a series of imidazolium-based ILs (C4mimA, A-=PF6-, Tf2N-, BF4- and C4mim=1-methyl-3-butyl-imidazolium) as well as in the Me3NBuTf2N IL. The solubility and dissociation of the uranyl salts are found to depend on the nature of X- and A-. The addition of Cl- anions promotes the solubilization of the nitrate and triflate salts in the C4mimPF6 and the C4mimBF4 ILs via the formation of chloro complexes, also formed with other salts. The first coordination sphere of uranyl is further investigated by molecular dynamics (MD) simulations on associated versus dissociated forms of UO2X2 salts in C4mimA ILs as a function of A- and X- anions. Furthermore, the comparison of UO2Cl(4)2-, 2 X- complexes with dissociated X- anions, to the UO2X2, 4 Cl- complexes with dissociated chlorides, shows that the former is more stable. The case of fluoro complexes is also considered, as a possible result of fluorinated IL anion's degradation, showing that UO2F42- should be most stable in solution. In all cases, uranyl is found to be solvated as formally anionic UO2XnAmClp2-n-m-p complexes, embedded in a cage of stabilizing IL imidazolium or ammonium cations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brommage, Jr., Robert J.

The skeleton is recognized as a crucial organ in the minute-to-minute regulation of the blood levels of calcium and phosphate. The fluxes of calcium and phosphate to and from bone greatly exceed the entry and exit of these ions occurring in the intestine and kidneys. Parathyroid hormone, calcitonin, and 1,25-dihydroxyvitamin D 3 (1,25-(OH) 2D 3 are known to influence the transfer of calcium and phosphate from bone to blood. Three mechanisms have been proposed to explain the hormonal control of the calcium and phosphate effluxes from bone. The concept of a bone membrane maintaining a distinct bone extracellular fluid compositionmore » has led to the pump and pH gradient theories. An alternate solubilizer theory proposes that bone cells secrete a substance which increases the solubility of the bone mineral. The bone membrane concept was originally proposed to explain the presence of the apparent anomalously high concentrations of potassium in the bone extracellular fluid. However, the available evidence does not allow an unambiguous decision concerning the presence of a bone membrane. Calvarial lactate production was unaltered by 1,25-(OH) 2D 3 treatment and consequently 1,25-(OH) 2D 3 does not appear to promote the mobilization of bone mineral through a lactate-mediated pH gradient mechanism. 1,25-(OH) 2D 3 did increase the solubility of non-vital bone, clearly demonstrating that the solubilizer mechanism is at least partially responsible for the mobilization of bone mineral and the regulation of blood levels of calcium and phosphate. Vitamin D-deficient female rats fed a 0.2% calcium, 0.4% phosphorous diet and supplemented with daily injections of 0.75 pmole of 1,25-(OH) 2D 3 were shown to be capable of bearing young. When the injections of 1,25-(OH) 2D 3 were terminated at delivery, the dams and pups showed signs of vitamin D deficiency approximately one week later.« less

The molecular structure of the phosphate mineral kidwellite NaFe93+(PO4)6(OH)11ṡ3H2O - A vibrational spectroscopic study

NASA Astrophysics Data System (ADS)

Frost, Ray L.; López, Andrés; Theiss, Frederick L.; Scholz, Ricardo; Souza, Larissa

2014-09-01

The mineral kidwellite, a hydrated hydroxy phosphate of ferric iron and sodium of approximate formula NaFe93+(PO4)6(OH)11ṡ3H2O, has been studied using a combination of electron microscopy with EDX and vibrational spectroscopic techniques. Raman spectroscopy identifies an intense band at 978 cm-1 and 1014 cm-1. These bands are attributed to the PO43- ν1 symmetric stretching mode. The ν3 antisymmetric stretching modes are observed by a large number of Raman bands. The series of Raman bands at 1034, 1050, 1063, 1082, 1129, 1144 and 1188 cm-1 are attributed to the ν3 antisymmetric stretching bands of the PO43- and HOPO32- units. The observation of these multiple Raman bands in the symmetric and antisymmetric stretching region gives credence to the concept that both phosphate and hydrogen phosphate units exist in the structure of kidwellite. The series of Raman bands at 557, 570, 588, 602, 631, 644 and 653 cm-1are assigned to the PO43- ν2 bending modes. The series of Raman bands at 405, 444, 453, 467, 490 and 500 cm-1 are attributed to the PO43- and HOPO32- ν4 bending modes. The spectrum is quite broad but Raman bands may be resolved at 3122, 3231, 3356, 3466 and 3580 cm-1. These bands are assigned to water stretching vibrational modes. The number and position of these bands suggests that water is in different molecular environments with differing hydrogen bond distances. Infrared bands at 3511 and 3359 cm-1 are ascribed to the OH stretching vibration of the OH units. Very broad bands at 3022 and 3299 cm-1 are attributed to the OH stretching vibrations of water. Vibrational spectroscopy offers insights into the molecular structure of the phosphate mineral kidwellite.

A vibrational spectroscopic study of the phosphate mineral lulzacite Sr2Fe2+(Fe2+,Mg)2Al4(PO4)4(OH)10

NASA Astrophysics Data System (ADS)

Frost, Ray L.; López, Andrés; Belotti, Fernanda M.; Xi, Yunfei; Scholz, Ricardo

2014-06-01

The mineral lulzacite from Saint-Aubin des Chateaux mine, France, with theoretical formula Sr2Fe2+(Fe2+,Mg)2Al4(PO4)4(OH)10 has been studied using a combination of electron microscopy with EDX and vibrational spectroscopic techniques. Chemical analysis shows a Sr, Fe, Al phosphate with minor amounts of Ga, Ba and Mg. Raman spectroscopy identifies an intense band at 990 cm-1 with an additional band at 1011 cm-1. These bands are attributed to the PO43-ν1 symmetric stretching mode. The ν3 antisymmetric stretching modes are observed by a large number of Raman bands. The Raman bands at 1034, 1051, 1058, 1069 and 1084 together with the Raman bands at 1098, 1116, 1133, 1155 and 1174 cm-1 are assigned to the ν3 antisymmetric stretching vibrations of PO43- and the HOPO32- units. The observation of these multiple Raman bands in the symmetric and antisymmetric stretching region gives credence to the concept that both phosphate and hydrogen phosphate units exist in the structure of lulzacite. The series of Raman bands at 567, 582, 601, 644, 661, 673 and 687 cm-1 are assigned to the PO43-ν2 bending modes. The series of Raman bands at 437, 468, 478, 491, 503 cm-1 are attributed to the PO43- and HOPO32-ν4 bending modes. No Raman bands of lulzacite which could be attributed to the hydroxyl stretching unit were observed. Infrared bands at 3511 and 3359 cm-1 are ascribed to the OH stretching vibration of the OH units. Very broad bands at 3022 and 3299 cm-1 are attributed to the OH stretching vibrations of water. Vibrational spectroscopy offers insights into the molecular structure of the phosphate mineral lulzacite.

Effect of Biomineralization Ability on Push-out Strength of Proroot Mineral Trioxide Aggregate, Mineral Trioxide Aggregate Branco, and Calcium Phosphate Cement on Dentin: An In vitro Evaluation.

PubMed

Revankar, Vanita D; Prathap, M S; Shetty, K Harish Kumar; Shahul, Azmin; Sahana, K

2017-11-01

Biomineralization is a process which leads to the formation of an interfacial layer with tag-like structures at the cement-dentin interface. It is due to interaction of mineral trioxide aggregate (MTA) and Portland cement with dentin in phosphate-buffered solution (PBS). This study is aimed to evaluate the effect of influence of biomineralization process on push-out bond strength of ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK, USA), MTA Branco (Angelus Soluc¸o˜es Odontolo´gicas, Londrina, PR, Brazil) and calcium phosphate cement (BioGraft CPC). The aim of this study was to evaluate the effect of biomineralization process on the push-out strength of ProRoot MTA, MTA Branco, and CPC after mixing with 0.2% chlorhexidine gluconate solution (0.2% CHX) and 2% lidocaine solution (2% LA) on the bond strength of MTA-dentin. Dentin discs with uniform cavities were restored with ProRoot MTA, MTA Branco, and calcium phosphate cement after mixing with 0.2% CHX solution and 2% lidocaine solution. The samples were uniformly distributed into two groups. Experimental group being immersed in PBS solution and control group being immersed in saline for 2 months. Instron testing machine (Model 4444; Instron Corp., Canton, MA, USA) was used to determine the bond strength. A two-way analysis of variance and post hoc analysis by Bonferroni test. All samples immersed in experimental group displayed a significantly greater resistance to displacement than that observed for the samples in control group ( P < 0.05). MTAs displayed a significantly greater resistance to displacement than calcium phosphate cements. The main conclusion of this study was that the push-out bond strength of the cements, mainly the MTA groups, was positively influenced by the biomineralization process.

Ultrastructure and biological function of matrix vesicles in bone mineralization.

PubMed

Hasegawa, Tomoka

2018-04-01

Bone mineralization is initiated by matrix vesicles, small extracellular vesicles secreted by osteoblasts, inducing the nucleation and subsequent growth of calcium phosphate crystals inside. Although calcium ions (Ca 2+ ) are abundant throughout the tissue fluid close to the matrix vesicles, the influx of phosphate ions (PO4 3- ) into matrix vesicles is a critical process mediated by several enzymes and transporters such as ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), ankylosis (ANK), and tissue nonspecific alkaline phosphatase (TNSALP). The catalytic activity of ENPP1 in osteoblasts generates inorganic pyrophosphate (PPi) intracellularly and extracellularly, and ANK may allow the intracellular PPi to pass through the plasma membrane to the outside of the osteoblasts. Although the extracellular PPi binds to growing hydroxyapatite crystals to prevent crystal overgrowth, TNSALP on the osteoblasts and matrix vesicles hydrolyzes PPi into PO4 3- monomers: the prevention of crystal growth is blocked, and PO4 3- monomers are supplied to matrix vesicles. In addition, PHOSPHO1 is thought to function inside matrix vesicles to catalyze phosphocoline, a constituent of the plasma membrane, consequently increasing PO4 3- in the vesicles. Accumulation of Ca 2+ and PO4 3- inside the matrix vesicles then initiates crystalline nucleation associated with the inner leaflet of the matrix vesicles. Calcium phosphate crystals elongate radially, penetrate the matrix vesicle's membrane, and finally grow out of the vesicles to form calcifying nodules, globular assemblies of needle-shaped mineral crystals retaining some of those transporters and enzymes. The subsequent growth of calcifying nodules appears to be regulated by surrounding organic compounds, finally leading to collagen mineralization.

Removal of uranyl ions by p-hexasulfonated calyx[6]arene acid

NASA Astrophysics Data System (ADS)

Popescu (Hoştuc), Ioana-Carmen; Petru, Filip; Humelnicu, Ionel; Mateescu, Marina; Militaru, Ecaterina; Humelnicu, Doina

2014-10-01

Radioactive pollution is a significant threat for the people's health. Therefore highly effective radioactive decontamination methods are required. Ion exchange, biotechnologies and phytoremediation in constructed wetlands have been used as radioactive decontamination technologies for uranium contaminated soil and water remediation. Recently, beside those classical methods the calix[n]arenic derivatives' utilization as radioactive decontaminators has jogged attention. The present work aims to present the preliminary research results of uranyl ion sorption studies on the p-hexasulfonated calyx[6]arenic acid. The effect of temperature, contact time, sorbent amount and uranyl concentration variation on sorption efficiency was investigated. Isotherm models revealed that the sorption process fit better Langmuir isotherm.

Effects of pH on the Production of Phosphate and Pyrophosphate by Matrix Vesicles' Biomimetics

PubMed Central

Simão, Ana Maria S.; Bolean, Maytê; Hoylaerts, Marc F.; Millán, José Luis; Ciancaglini, Pietro

2013-01-01

During endochondral bone formation, chondrocytes and osteoblasts synthesize and mineralize the extracellular matrix through a process that initiates within matrix vesicles (MVs) and ends with bone mineral propagation onto the collagenous scaffold. pH gradients have been identified in the growth plate of long bones, but how pH changes affect the initiation of skeletal mineralization is not known. Tissue-nonspecific alkaline phosphatase (TNAP) degrades extracellular inorganic pyrophosphate (ePPi), a mineralization inhibitor produced by ectonucleotide pyrophosphatase/ phosphodiesterase-1 (NPP1), while contributing Pi from ATP to initiate mineralization. TNAP and NPP1, alone or combined, were reconstituted in dipalmitoylphosphatidylcholine (DPPC) liposomes to mimic the microenvironment of MVs. The hydrolysis of ATP, ADP, AMP and PPi was studied at pH 8 and 9 and compared to the data determined at pH 7.4. While catalytic efficiencies in general were higher at alkaline pH, PPi hydrolysis was maximal at pH 8 and indicated a preferential utilization of PPi over ATP, at pH 8 versus 9. In addition, all proteoliposomes induced mineral formation when incubated in a synthetic cartilage lymph (SCL) containing 1 mM ATP as substrate and amorphous calcium phosphate (ACP) or calciumphosphate- phosphatidylserine complexes (PS-CPLX) as nucleators. Propagation of mineralization was significantly more efficient at pHs 7.5 and 8 than at pH 9. Since a slight pH elevation from 7.4 to 8 promotes considerably more hydrolysis of ATP, ADP and AMP primarily by TNAP, this small pH change facilitates mineralization, especially via upregulated PPi hydrolysis by both NPP1 and TNAP, further elevating the Pi/PPi ratio, thus enhancing bone mineralization. PMID:23942722

A systematic study of multiple minerals precipitation modelling in wastewater treatment.

PubMed

Kazadi Mbamba, Christian; Tait, Stephan; Flores-Alsina, Xavier; Batstone, Damien J

2015-11-15

Mineral solids precipitation is important in wastewater treatment. However approaches to minerals precipitation modelling are varied, often empirical, and mostly focused on single precipitate classes. A common approach, applicable to multi-species precipitates, is needed to integrate into existing wastewater treatment models. The present study systematically tested a semi-mechanistic modelling approach, using various experimental platforms with multiple minerals precipitation. Experiments included dynamic titration with addition of sodium hydroxide to synthetic wastewater, and aeration to progressively increase pH and induce precipitation in real piggery digestate and sewage sludge digestate. The model approach consisted of an equilibrium part for aqueous phase reactions and a kinetic part for minerals precipitation. The model was fitted to dissolved calcium, magnesium, total inorganic carbon and phosphate. Results indicated that precipitation was dominated by the mineral struvite, forming together with varied and minor amounts of calcium phosphate and calcium carbonate. The model approach was noted to have the advantage of requiring a minimal number of fitted parameters, so the model was readily identifiable. Kinetic rate coefficients, which were statistically fitted, were generally in the range 0.35-11.6 h(-1) with confidence intervals of 10-80% relative. Confidence regions for the kinetic rate coefficients were often asymmetric with model-data residuals increasing more gradually with larger coefficient values. This suggests that a large kinetic coefficient could be used when actual measured data is lacking for a particular precipitate-matrix combination. Correlation between the kinetic rate coefficients of different minerals was low, indicating that parameter values for individual minerals could be independently fitted (keeping all other model parameters constant). Implementation was therefore relatively flexible, and would be readily expandable to include other minerals. Copyright © 2015 Elsevier Ltd. All rights reserved.

Undiscovered phosphate resources in the Caribbean region and their potential value for agricultural development

USGS Publications Warehouse

Sheldon, Richard Porter; Davidson, D.F.; Riggs, S.R.; Burnett, W.C.

1985-01-01

The countries of the world's humid tropical regions lack the soil fertility necessary for high agricultural productivity. A recently developed agricultural technology that increases soil fertility can make tropical agriculture highly productive, but the technique requires large inputs into the soil of phosphorus and other fertilizers and soil amendments. Use of fertilizers derived from phosphate rock is increasing greatly throughout the world, and fertilizer raw materials are being produced more and more frequently from phosphate rock deposits close to the areas of use. An increased understanding of the origin of phosphate rock in ancient oceans has enabled exploration geologists to target areas of potential mineral resource value and to search directly for deposits. However, because of the difficulty of prospecting for mineral deposits in forested tropical regions, phosphate rock deposits are not being explored for in the countries of the humid tropics, including most countries of the Caribbean region. As a result, the countries of the Caribbean must import phosphate rock or phosphorus fertilizer products. In the present trade market, imports of phosphate are too low for the initiation of new agricultural technology in the Caribbean and Central American region. A newly proposed program of discovery and development of undiscovered phosphate rock deposits revolves around reconnaissance studies, prospecting by core drilling, and analysis of bulk samples. The program should increase the chance of discovering economic phosphate rock deposits. The search for and evaluation of phosphate rock resources in the countries of the Caribbean region would take about 5 years and cost an average of $15 million per country. The program is designed to begin with high risk-low cost steps and end with low risk-high cost steps. A successful program could improve the foreign exchange positions of countries in the Caribbean region by adding earnings from agricultural product exports and by substituting domestically produced phosphate rock and fertilizer products for imported phosphate fertilizers. A successful program also could provide enough domestically produced phosphorus fertilizer products to allow initiation of new agricultural technology in the region and thus increase domestic food production. Finally, a new phosphorus fertilizer industry would create new jobs in the mining, chemical, and transportation industries of the Caribbean region.

Process for the extraction of technetium from uranium

DOEpatents

Gong, Cynthia-May S.; Poineau, Frederic; Czerwinski, Kenneth R.

2010-12-21

A spent fuel reprocessing method contacts an aqueous solution containing Technetium(V) and uranyl with an acidic solution comprising hydroxylamine hydrochloride or acetohydroxamic acid to reduce Tc(V) to Tc(II, and then extracts the uranyl with an organic phase, leaving technetium(II) in aqueous solution.

Negative Stains Containing Trehalose: Application to Tubular and Filamentous Structures

NASA Astrophysics Data System (ADS)

Harris, J. Robin; Gerber, Max; Gebauer, Wolfgang; Wernicke, Wolfgang; Markl, Jürgen

1996-02-01

Several examples are presented that show the successful application of uranyl acetate and ammonium molybdate negative staining in the presence of trehalose for TEM studies of filamentous and tubular structures. The principal benefit to be gained from the inclusion of trehalose stems from the considerably reduced flattening of the large tubular structures and the greater orientational freedom of single molecules due to an increased depth of the negative stain in the presence of trehalose. Trehalose is likely to provide considerable protection to protein molecules and their assemblies during the drying of negatively stained specimens. Some reduction in the excessive density imparted by uranyl acetate around large assemblies is also achieved. Nevertheless, in the presence of 1% (w/v) trehalose, it is desirable to increase the concentration of negative stain to 5% (w/v) for ammonium molybdate and to 4% for uranyl acetate to produce satisfactory image contrast. In general, the ammonium molybdate-trehalose negative stain is more satisfactory than the uranyl acetate-trehalose combination, because of the greater electron beam sensitivity of the uranyl negative stain. Reassembled taxol-stabilized pig brain microtubules, together with collagen fibrils, sperm tails, helical filaments, and reassociated hemocyanin (KLH2), all from the giant keyhole limpet Megathura crenulata, have been studied by negative staining in the presence of trehalose. In all cases satisfactory TEM imaging conditions were readily obtained on the specimens, as long as regions of excessively deep stain were avoided.

Inhibition of poly(ADP-ribose)polymerase-1 and DNA repair by uranium

PubMed Central

Cooper, Karen L.; Dashner, Erica J.; Tsosie, Ranalda; Cho, Young Mi; Lewis, Johnnye

2015-01-01

Uranium has radiological and non-radiological effects within biological systems and there is increasing evidence for genotoxic and carcinogenic properties attributable to uranium through its heavy metal properties. In this study, we report that low concentrations of uranium (as uranyl acetate; <10 μM) is not cytotoxic to human embryonic kidney cells or normal human keratinocytes; however, uranium exacerbates DNA damage and cytotoxicity induced by hydrogen peroxide, suggesting that uranium may inhibit DNA repair processes. Concentrations of uranyl acetate in the low micromolar range inhibited the zinc finger DNA repair protein poly(ADP-ribose) polymerase (PARP)-1 and caused zinc loss from PARP-1 protein. Uranyl acetate exposure also led to zinc loss from the zinc finger DNA repair proteins Xeroderma Pigmentosum, Complementation Group A (XPA) and aprataxin (APTX). In keeping with the observed inhibition of zinc finger function of DNA repair proteins, exposure to uranyl acetate enhanced retention of induced DNA damage. Co-incubation of uranyl acetate with zinc largely overcame the impact of uranium on PARP-1 activity and DNA damage. These findings present evidence that low concentrations of uranium can inhibit DNA repair through disruption of zinc finger domains of specific target DNA repair proteins. This may provide a mechanistic basis to account for the published observations that uranium exposure is associated with DNA repair deficiency in exposed human populations. PMID:26627003

Inhibition of poly(ADP-ribose)polymerase-1 and DNA repair by uranium.

PubMed

Cooper, Karen L; Dashner, Erica J; Tsosie, Ranalda; Cho, Young Mi; Lewis, Johnnye; Hudson, Laurie G

2016-01-15

Uranium has radiological and non-radiological effects within biological systems and there is increasing evidence for genotoxic and carcinogenic properties attributable to uranium through its heavy metal properties. In this study, we report that low concentrations of uranium (as uranyl acetate; <10 μM) is not cytotoxic to human embryonic kidney cells or normal human keratinocytes; however, uranium exacerbates DNA damage and cytotoxicity induced by hydrogen peroxide, suggesting that uranium may inhibit DNA repair processes. Concentrations of uranyl acetate in the low micromolar range inhibited the zinc finger DNA repair protein poly(ADP-ribose) polymerase (PARP)-1 and caused zinc loss from PARP-1 protein. Uranyl acetate exposure also led to zinc loss from the zinc finger DNA repair proteins Xeroderma Pigmentosum, Complementation Group A (XPA) and aprataxin (APTX). In keeping with the observed inhibition of zinc finger function of DNA repair proteins, exposure to uranyl acetate enhanced retention of induced DNA damage. Co-incubation of uranyl acetate with zinc largely overcame the impact of uranium on PARP-1 activity and DNA damage. These findings present evidence that low concentrations of uranium can inhibit DNA repair through disruption of zinc finger domains of specific target DNA repair proteins. This may provide a mechanistic basis to account for the published observations that uranium exposure is associated with DNA repair deficiency in exposed human populations. Copyright © 2015 Elsevier Inc. All rights reserved.

Rietveld Refinement on X-Ray Diffraction Patterns of Bioapatite in Human Fetal Bones

PubMed Central

Meneghini, Carlo; Dalconi, Maria Chiara; Nuzzo, Stefania; Mobilio, Settimio; Wenk, Rudy H.

2003-01-01

Bioapatite, the main constituent of mineralized tissue in mammalian bones, is a calcium-phosphate-based mineral that is similar in structure and composition to hydroxyapatite. In this work, the crystallographic structure of bioapatite in human fetuses was investigated by synchrotron radiation x-ray diffraction (XRD) and microdiffraction (μ-XRD) techniques. Rietveld refinement analyses of XRD and μ-XRD data allow for quantitative probing of the structural modifications of bioapatite as functions of the mineralization process and gestational age. PMID:12609904

McCrillisite, NaCs(Be,Li)Zr2(PO4)4.1-2H2O, a new mineral species from Mount Mica, Oxford County, Maine, and new data for gainesite

USGS Publications Warehouse

Foord, E.E.; Brownfield, M.E.; Lichte, F.E.; Davis, A.M.; Sutley, S.J.

1994-01-01

McCrillisite, a member of the gainesite group, occurs in the Mount Mica granitic pegmatite, South Paris, Oxford County, Maine. The mineral is a product of late-stage hydrothermal alteration and is associated with approximately 20 other silicate, oxide, carbonate, arsenite and phosphate minerals. Crystals occur in mm- to cm-sized cavities, and individuals are up to 1.2 mm in maximum dimension. The crystallography and mineral chemistry of McCrillisite are described. -from Authors

Development of a new biofertilizer with a high capacity for N2 fixation, phosphate and potassium solubilization and auxin production.

PubMed

Leaungvutiviroj, Chaveevan; Ruangphisarn, Pimtida; Hansanimitkul, Pikul; Shinkawa, Hidenori; Sasaki, Ken

2010-01-01

Biofertilizers that possess a high capacity for N(2) fixation (Azotobacter tropicalis), and consist of phosphate solubilizing bacteria (Burkhoderia unamae), and potassium solubilizing bacteria (Bacillus subtilis) and produce auxin (KJB9/2 strain), have a high potential for growth and yield enhancement of corn and vegetables (Chinese kale). For vegetables, the addition of biofertilizer alone enhanced growth 4 times. Moreover, an enhancement of growth by 7 times was observed due to the addition of rock phosphate and K-feldspar, natural mineral fertilizers, in combination with the biofertilizer.

Geology and phosphate resources of the Hawley Creek area, Lemhi County, Idaho

USGS Publications Warehouse

Oberlindacher, Peter; Hovland, Robert David

1979-01-01

Phosphate resources occur within the Retort Phosphatic Shale Member of the Permian Phosphoria Formation in the Hawley Creek area, near Leadore, in east-central Idaho. About 12 square miles (31 km2 ) of the Retort Member and enclosing rocks were mapped at a scale of 1:12,000 to evaluate the leasable Federal mineral resources. The Retort has an average thickness of 73 feet (22.3 m) and 12.9 linear miles (20.8 linear km) of outcrop within the area mapped. Rock samples taken from a bulldozer trench were analyzed for phosphate content and for minor trace elements. Analyses show a cumulative thickness of 8.7 feet ( 2.7 m) of medium-grade phosphate rock ( 24 to 31 percent P2O5) and 33.4 feet (10.2 m) of low-grade phosphate rock (16 to 24 percent P2O5). Minor elements in the Retort include uranium, vanadium, fluorine, cadmium, chromium, nickel, molybdenum, silver, and rare earths. These minor elements are potential byproducts of any future phosphate production in the Hawley Creek area. In addition, analyses of six phosphate rock samples taken from a prospect trench show a cumulative thickness of 14.9 ft (4.5 m) at 17.6 percent P2O5. Indicated phosphate resources are calculated for phosphate beds under less than 600 feet (183.0 m) of overburden. Approximately 36.5 feet (11.1 m), representing 50 percent of the total Retort Member, were measured in trench CP-71. There are 80.42 million short tons (72.96 million metric tons) of medium-grade phosphate rock, and 308.76 million short tons ( 280.10 million metric tons) of low-grade phosphate rock in the Retort Member within the map area. Because the thickness and grade of the phosphate beds for each block are based on the recovered section from CP-71, the calculated phosphate resource estimates represent a minimum. Other mineral resources in the area are thorium (35 ppm) in a Precambrian (?) granite body located immediately west of the Hawley Creek area; oil and gas accumulations may occur beneath the Medicine Lodge thrust system in this part of the Beaverhead Mountains. Paleozoic, Mesozoic, and Cenozoic rocks are present in the Hawley Creek area. Fold axes and thrust faults have a dominant northwest trend. These thrusts and folds are probably associated with the northeast-oriented stress field that existed in Late Cretaceous time. Evidence of younger, high-angle normal and reverse faults in the area also exists.

Polymeric additives to enhance the functional properties of calcium phosphate cements

PubMed Central

Perez, Roman A; Kim, Hae-Won

2012-01-01

The vast majority of materials used in bone tissue engineering and regenerative medicine are based on calcium phosphates due to their similarity with the mineral phase of natural bone. Among them, calcium phosphate cements, which are composed of a powder and a liquid that are mixed to obtain a moldable paste, are widely used. These calcium phosphate cement pastes can be injected using minimally invasive surgery and adapt to the shape of the defect, resulting in an entangled network of calcium phosphate crystals. Adding an organic phase to the calcium phosphate cement formulation is a very powerful strategy to enhance some of the properties of these materials. Adding some water-soluble biocompatible polymers in the calcium phosphate cement liquid or powder phase improves physicochemical and mechanical properties, such as injectability, cohesion, and toughness. Moreover, adding specific polymers can enhance the biological response and the resorption rate of the material. The goal of this study is to overview the most relevant advances in this field, focusing on the different types of polymers that have been used to enhance specific calcium phosphate cement properties. PMID:22511991

Probing hydrogen and halogen-oxo interactions in uranyl coordination polymers: a combined crystallographic and computational study

DOE PAGES

Carter, Korey P.; Kalaj, Mark; Kerridge, Andrew; ...

2018-01-01

Four uranyl compounds containing either benzoic acid ( 1 ), m -chlorobenzoic acid ( 2 ), m -bromobenzoic acid ( 3 ), or m -iodobenzoic acid ( 4 ) are described, and the latter two compounds are used to probe non-covalent interaction strengths via structural, vibrational, and computational means.

Short-term effects of mineral particle sizes on cellular degradation activity after implantation of injectable calcium phosphate biomaterials and the consequences for bone substitution.

PubMed

Gauthier, O; Bouler, J M; Weiss, P; Bosco, J; Aguado, E; Daculsi, G

1999-08-01

This in vivo study investigated the influence of two calcium phosphate particle sizes (40-80 microm and 200-500 microm) on the cellular degradation activity associated with the bone substitution process of two injectable bone substitutes (IBS). The tested biomaterials were obtained by associating a biphasic calcium phosphate (BCP) ceramic mineral phase and a 3% aqueous solution of a cellulosic polymer (hydroxypropylmethylcellulose). Both were injected into osseous defects at the distal end of rabbit femurs for 2- and 3-week periods. Quantitative results for tartrate-resistant acid phosphatase (TRAP) cellular activity, new bone formation, and ceramic resorption were studied for statistical purposes. Positive TRAP-stained degradation cells were significantly more numerous for IBS 40-80 than IBS 200-500, regardless of implantation time. BCP degradation was quite marked during the first 2 weeks for IBS 40-80, and bone colonization occurred more extensively for IBS 40-80 than for IBS 200-500. The resorption-bone substitution process occurred earlier and faster for IBS 40-80 than IBS 200-500. Both tested IBS displayed similar biological efficiency, with conserved in vivo bioactivity and bone-filling ability. Differences in calcium phosphate particle sizes influenced cellular degradation activity and ceramic resorption but were compatible with efficient bone substitution.

δ18O of apatite phosphate in small pelagic fish: insights from wild-caught and tank-grown specimens

NASA Astrophysics Data System (ADS)

Lambert, T.; Javor, B.; Paytan, A.

2011-12-01

Oxygen isotope ratios of mineralized structures in fish reflect the temperature and isotopic composition of the water in which they grow. For bulk samples (e.g., whole scales, bones, and otoliths), understanding how this signal is integrated across time and space is critical, especially for organisms exposed to high variability in growth conditions. Here, we assess the response of fish scale δ18O (from apatite phosphate) to experimentally manipulated water conditions. Wild-caught sardines were grown at controlled temperatures (13°C, 17°C, and 21°C) for 11 months. Higher growth temperatures correlated to lower δ18O values, representing a combination of scale apatite deposited before and after the temperature manipulation. Models that account for both biomineral allometry and exposure to varying water properties (e.g., by overlaying migration routes, isoscapes, and temperature maps) have the potential to quantify the varying contributions of minerals grown under different conditions. We use this method to predict δ18O of apatite phosphate for small pelagic fish found in California coastal waters, then compare expected values to those obtained from collected samples. Since phosphate oxygen is relatively resistant to diagenesis, this modern calibration establishes a framework for paleo studies.

Dental caries in diabetes mellitus: role of salivary flow rate and minerals.

PubMed

Jawed, Muhammad; Shahid, Syed M; Qader, Shah A; Azhar, Abid

2011-01-01

This study was designed to evaluate the possible protective role of salivary factors like salivary flow rate and adequate level of calcium, phosphate, and fluoride in diabetes mellitus type 2 patients with dental caries. A total of 398 diabetes mellitus type 2 patients with dental caries and 395 age- and sex-matched non-diabetic subjects with dental caries were included as controls, all of whom gave informed consent. All subjects were divided into four groups according to their age. Decayed, missed, and filled teeth (DMFT) were scored to indicate the severity of dental caries. Saliva was collected, flow rate was noted, and calcium, phosphate, and fluoride were analyzed. The blood glucose, HbA1c, and DMFT indices were found to be significantly high in diabetic patients as compared to controls. The salivary flow rate, calcium, phosphate, and fluoride were found to be significantly low whereas no significant difference was found in salivary magnesium in patients as compared to controls. Optimum salivary flow rate is responsible for establishing protective environment against dental caries. Adequate level of salivary calcium, phosphate, and fluoride is also involved in significant deposition of these minerals in plaque, which greatly reduces the development of caries in the adjacent enamel of teeth. Copyright © 2011 Elsevier Inc. All rights reserved.

Tooth dentin defects reflect genetic disorders affecting bone mineralization

PubMed Central

Vital, S. Opsahl; Gaucher, C.; Bardet, C.; Rowe, P.S.; George, A.; Linglart, A.; Chaussain, C.

2012-01-01

Several genetic disorders affecting bone mineralization may manifest during dentin mineralization. Dentin and bone are similar in several aspects, especially pertaining to the composition of the extracellular matrix (ECM) which is secreted by well-differentiated odontoblasts and osteoblasts, respectively. However, unlike bone, dentin is not remodelled and is not involved in the regulation of calcium and phosphate metabolism. In contrast to bone, teeth are accessible tissues with the shedding of deciduous teeth and the extractions of premolars and third molars for orthodontic treatment. The feasibility of obtaining dentin makes this a good model to study biomineralization in physiological and pathological conditions. In this review, we focus on two genetic diseases that disrupt both bone and dentin mineralization. Hypophosphatemic rickets is related to abnormal secretory proteins involved in the ECM organization of both bone and dentin, as well as in the calcium and phosphate metabolism. Osteogenesis imperfecta affects proteins involved in the local organization of the ECM. In addition, dentin examination permits evaluation of the effects of the systemic treatment prescribed to hypophosphatemic patients during growth. In conclusion, dentin constitutes a valuable tool for better understanding of the pathological processes affecting biomineralization. PMID:22296718

Loss of DMP1 causes rickets and osteomalacia and identifies a role for osteocytes in mineral metabolism

PubMed Central

Feng, Jian Q; Ward, Leanne M; Liu, Shiguang; Lu, Yongbo; Xie, Yixia; Yuan, Baozhi; Yu, Xijie; Rauch, Frank; Davis, Siobhan I; Zhang, Shubin; Rios, Hector; Drezner, Marc K; Quarles, L Darryl; Bonewald, Lynda F; White, Kenneth E

2007-01-01

The osteocyte, a terminally differentiated cell comprising 90%–95% of all bone cells1,2, may have multiple functions, including acting as a mechanosensor in bone (re)modeling3. Dentin matrix protein 1 (encoded by DMP1) is highly expressed in osteocytes4 and, when deleted in mice, results in a hypomineralized bone phenotype5. We investigated the potential for this gene not only to direct skeletal mineralization but also to regulate phosphate (Pi) homeostasis. Both Dmp1- null mice and individuals with a newly identified disorder, autosomal recessive hypophosphatemic rickets, manifest rickets and osteomalacia with isolated renal phosphate-wasting associated with elevated fibroblast growth factor 23 (FGF23) levels and normocalciuria. Mutational analyses showed that autosomal recessive hypophosphatemic rickets family carried a mutation affecting the DMP1 start codon, and a second family carried a 7-bp deletion disrupting the highly conserved DMP1 C terminus. Mechanistic studies using Dmp1-null mice demonstrated that absence of DMP1 results in defective osteocyte maturation and increased FGF23 expression, leading to pathological changes in bone mineralization. Our findings suggest a bone-renal axis that is central to guiding proper mineral metabolism. PMID:17033621

Wilderness study area, mineral resources of the Sleeping Giant, Lewis and Clark County, Montana

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tysdal, G.; Reynold, M.W.; Carlson, R.R.

1991-01-01

A Mineral resource survey was conducted in 1987 by the U.S. Geological Survey and the U.S. Bureau of Mines to evaluate mineral resources (known) and mineral resource potential (undiscovered) of the Sleeping Giant Wilderness Study Area (MT-075-111) in Lewis and Clark County, Montana. The only economic resource in the study area is an inferred 1.35-million-ton reserve of decorative stone (slate); a small gold placer resource is subeconomic. A high resource potential for decorative slate exists directly adjacent to the area of identified slate resource and in the northeastern part of the study area. The rest of the study area hasmore » a low potential for decorative slate. The westernmost part of the study area has a moderate resource potential for copper and associated silver in state-bound deposits in green beds and limestone; potential is low in the rest of the study are. The study area has a low resource potential for sapphires in placer deposits, gold in placer deposits (exclusive of subeconomic resource mentioned above), phosphate in the Spokane Formation, diatomite in lake deposits, uranium, oil, gas, geothermal energy, and no resource potential for phosphate in the Phosphoria Formation.« less

Investigating Microbial Biofilm Formations on Crustal Rock Substrates

NASA Astrophysics Data System (ADS)

Weiser, M.; D'Angelo, T.; Carr, S. A.; Orcutt, B.

2017-12-01

Ocean crust hosts microbial life that, in some cases, alter the component rocks as a means of obtaining energy. Variations in crust lithology, included trace metal and mineral content, as well as the chemistry of the fluids circulating through them, provide substrates for some microbes to metabolize, leading to formation of biofilm community structures. Microbes have different parameters for the situations in which they will form biofilms, but they must have some source of energy in excess at the site of biofilm formation for them to become stationary and form the carbohydrate-rich structures connecting the cells to one another and the substrate. Generally, the requirements for microbes to form biofilms on crustal minerals are unclear. We designed two experiments to test (1) mineral preference and biofilm formation rates by natural seawater microbial communities, and (2) biofilm development as a function of phosphate availability for an organism isolated from subseafloor ocean crust. In Experiment 1, we observed that phyric basalt groundmass is preferentially colonized over aphyric basalt or metal sulfides in a shallow water and oxic seawater environment. In experiment 2, tests of the anaerobic heterotroph Thalassospira bacteria isolated from oceanic crustal fluids showed that they preferentially form biofilms, lose motility, and increase exponentially in number over time in higher-PO4 treatments (50 micromolar), including with phosphate-doped basalts, than in treatments with low phosphate concentrations (0.5 micromolar) often found in crustal fluids. These observations suggest phosphate as a main driver of biofilm formation in subsurface crust. Overall, these data suggest that the drivers of microbial biofilm formation on crustal substrates are selective to the substrate conditions, which has important implications for estimating the global biomass of life harbored in oceanic crust.

Sucrose dependent mineral phosphate solubilization in Enterobacter asburiae PSI3 by heterologous overexpression of periplasmic invertases.

PubMed

Kumar, Chanchal; Wagh, Jitendra; Archana, G; Naresh Kumar, G

2016-12-01

Enterobacter asburiae PSI3 solubilizes mineral phosphates in the presence of glucose by the secretion of gluconic acid generated by the action of a periplasmic pyrroloquinoline quinone dependent glucose dehydrogenase. In order to achieve mineral phosphate solubilization phenotype in the presence of sucrose, plasmids pCNK4 and pCNK5 containing genes encoding the invertase enzyme of Zymomonas mobilis (invB) and of Saccharomyces cerevisiae (suc2) under constitutive promoters were constructed with malE signal sequence (in case of invB alone as the suc2 is secreted natively). When introduced into E. asburiae PSI3, E. a. (pCNK4) and E. a. (pCNK5) transformants secreted 21.65 ± 0.94 and 22 ± 1.3 mM gluconic acid, respectively, in the presence of 75 mM sucrose and they also solubilized 180 ± 4.3 and 438 ± 7.3 µM P from the rock phosphate. In the presence of a mixture of 50 mM sucrose and 25 mM glucose, E. a. (pCNK5) secreted 34 ± 2.3 mM gluconic acid and released 479 ± 8.1 µM P. Moreover, in the presence of a mixture of eight sugars (10 mM each) in the medium, E. a. (pCNK5) released 414 ± 5.3 µM P in the buffered medium. Thus, this study demonstrates incorporation of periplasmic invertase imparted P solubilization ability to E. asburiae PSI3 in the presence of sucrose and mixture of sugars.

Biomimetic remineralization of dentin.

PubMed

Niu, Li-Na; Zhang, Wei; Pashley, David H; Breschi, Lorenzo; Mao, Jing; Chen, Ji-Hua; Tay, Franklin R

2014-01-01

Remineralization of demineralized dentin is important for improving dentin bonding stability and controlling primary and secondary caries. Nevertheless, conventional dentin remineralization strategy is not suitable for remineralizing completely demineralized dentin within hybrid layers created by etch-and-rinse and moderately aggressive self-etch adhesive systems, or the superficial part of a caries-affected dentin lesion left behind after minimally invasive caries removal. Biomimetic remineralization represents a different approach to this problem by attempting to backfill the demineralized dentin collagen with liquid-like amorphous calcium phosphate nanoprecursor particles that are stabilized by biomimetic analogs of noncollagenous proteins. This paper reviewed the changing concepts in calcium phosphate mineralization of fibrillar collagen, including the recently discovered, non-classical particle-based crystallization concept, formation of polymer-induced liquid-precursors (PILP), experimental collagen models for mineralization, and the need for using phosphate-containing biomimetic analogs for biomimetic mineralization of collagen. Published work on the remineralization of resin-dentin bonds and artificial caries-like lesions by various research groups was then reviewed. Finally, the problems and progress associated with the translation of a scientifically sound concept into a clinically applicable approach are discussed. The particle-based biomimetic remineralization strategy based on the PILP process demonstrates great potential in remineralizing faulty hybrid layers or caries-like dentin. Based on this concept, research in the development of more clinically feasible dentin remineralization strategy, such as incorporating poly(anionic) acid-stabilized amorphous calcium phosphate nanoprecursor-containing mesoporous silica nanofillers in dentin adhesives, may provide a promising strategy for increasing of the durability of resin-dentin bonding and remineralizing caries-affected dentin. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Is bone transplantation the gold standard for repair of alveolar bone defects?

PubMed

Raposo-Amaral, Cassio Eduardo; Bueno, Daniela Franco; Almeida, Ana Beatriz; Jorgetti, Vanda; Costa, Cristiane Cabral; Gouveia, Cecília Helena; Vulcano, Luiz Carlos; Fanganiello, Roberto D; Passos-Bueno, Maria Rita; Alonso, Nivaldo

2014-01-01

New strategies to fulfill craniofacial bone defects have gained attention in recent years due to the morbidity of autologous bone graft harvesting. We aimed to evaluate the in vivo efficacy of bone tissue engineering strategy using mesenchymal stem cells associated with two matrices (bovine bone mineral and α-tricalcium phosphate), compared to an autologous bone transfer. A total of 28 adult, male, non-immunosuppressed Wistar rats underwent a critical-sized osseous defect of 5 mm diameter in the alveolar region. Animals were divided into five groups. Group 1 (n = 7) defects were repaired with autogenous bone grafts; Group 2 (n = 5) defects were repaired with bovine bone mineral free of cells; Group 3 (n = 5) defects were repaired with bovine bone mineral loaded with mesenchymal stem cells; Group 4 (n = 5) defects were repaired with α-tricalcium phosphate free of cells; and Group 5 (n = 6) defects were repaired with α-tricalcium phosphate loaded with mesenchymal stem cells. Groups 2-5 were compared to Group 1, the reference group. Healing response was evaluated by histomorphometry and computerized tomography. Histomorphometrically, Group 1 showed 60.27% ± 16.13% of bone in the defect. Groups 2 and 3 showed 23.02% ± 8.6% (p = 0.01) and 38.35% ± 19.59% (p = 0.06) of bone in the defect, respectively. Groups 4 and 5 showed 51.48% ± 11.7% (p = 0.30) and 61.80% ± 2.14% (p = 0.88) of bone in the defect, respectively. Animals whose bone defects were repaired with α-tricalcium phosphate and mesenchymal stem cells presented the highest bone volume filling the defects; both were not statistically different from autogenous bone.

Characteristics of a root hair-less line of Arabidopsis thaliana under physiological stresses.

PubMed

Tanaka, Natsuki; Kato, Mariko; Tomioka, Rie; Kurata, Rie; Fukao, Yoichiro; Aoyama, Takashi; Maeshima, Masayoshi

2014-04-01

The plasma membrane-associated Ca(2+)-binding protein-2 of Arabidopsis thaliana is involved in the growth of root hair tips. Several transgenic lines that overexpress the 23 residue N-terminal domain of this protein under the control of the root hair-specific EXPANSIN A7 promoter lack root hairs completely. The role of root hairs under normal and stress conditions was examined in one of these root hair-less lines (NR23). Compared with the wild type, NR23 showed a 47% reduction in water absorption, decreased drought tolerance, and a lower ability to adapt to heat. Growth of NR23 was suppressed in media deficient in phosphorus, iron, calcium, zinc, copper, or potassium. Also, the content of an individual mineral in NR23 grown in normal medium, or in medium lacking a specific mineral, was relatively low. In wild-type plants, the primary and lateral roots produce numerous root hairs that become elongated under phosphate-deficient conditions; NR23 did not produce root hairs. Although several isoforms of the plasma membrane phosphate transporters including PHT1;1-PHT1;6 were markedly induced after growth in phosphate-deficient medium, the levels induced in NR23 were less than half those observed in the wild type. In phosphate-deficient medium, the amounts of acid phosphatase, malate, and citrate secreted from NR23 roots were 38, 9, and 16% of the levels secreted from wild-type roots. The present results suggest that root hairs play significant roles in the absorption of water and several minerals, secretion of acid phosphatase(s) and organic acids, and in penetration of the primary roots into gels.

Synthesis, characterization, and in-vitro cytocompatibility of amorphous β-tri-calcium magnesium phosphate ceramics.

PubMed

Singh, Satish S; Roy, Abhijit; Lee, Boeun; Banerjee, Ipsita; Kumta, Prashant N

2016-10-01

Biphasic mixtures of crystalline β-tricalcium magnesium phosphate (β-TCMP) and an amorphous calcium magnesium phosphate have been synthesized and reported to support enhanced hMSC differentiation in comparison to β-tricalcium phosphate (β-TCP) due to the release of increased amounts of bioactive ions. In the current study, completely amorphous β-TCMP has been synthesized which is capable of releasing increased amounts of Mg(2+) and PO4(3-) ions, rather than a biphasic mixture as earlier reported. The amorphous phase formed was observed to crystallize between temperatures of 400-600°C. The scaffolds prepared with amorphous β-TCMP were capable of supporting enhanced hMSC proliferation and differentiation in comparison to commercially available β-TCP. However, a similar gene expression of mature osteoblast markers, OCN and COL-1, in comparison to biphasic β-TCMP was observed. To further study the role of Mg(2+) and PO4(3-) ions in regulating hMSC osteogenic differentiation, the capability of hMSCs to mineralize in growth media supplemented with Mg(2+) and PO4(3-) ions was studied. Interestingly, 5mM PO4(3-) supported mineralization while the addition of 5mM Mg(2+) to 5mM PO4(3-) inhibited mineralization. It was therefore concluded that the release of Ca(2+) ions from β-TCMP scaffolds also plays a role in regulating osteogenic differentiation on these scaffolds and it is noted that further work is required to more accurately determine the exact role of Mg(2+) in regulating hMSC osteogenic differentiation. Copyright © 2016 Elsevier B.V. All rights reserved.

The molecular structure of the phosphate mineral beraunite Fe2+Fe53+(PO4)4(OH)5ṡ4H2O - A vibrational spectroscopic study

NASA Astrophysics Data System (ADS)

Frost, Ray L.; López, Andrés; Scholz, Ricardo; Xi, Yunfei; Lana, Cristiano

2014-07-01

The mineral beraunite from Boca Rica pegmatite in Minas Gerais with theoretical formula Fe2+Fe53+(PO4)4(OH)5ṡ4H2O has been studied using a combination of electron microscopy with EDX and vibrational spectroscopic techniques. Raman spectroscopy identifies an intense band at 990 cm-1 and 1011 cm-1. These bands are attributed to the PO43- ν1 symmetric stretching mode. The ν3 antisymmetric stretching modes are observed by a large number of Raman bands. The Raman bands at 1034, 1051, 1058, 1069 and 1084 together with the Raman bands at 1098, 1116, 1133, 1155 and 1174 cm-1 are assigned to the ν3 antisymmetric stretching vibrations of PO43- and the HOPO32- units. The observation of these multiple Raman bands in the symmetric and antisymmetric stretching region gives credence to the concept that both phosphate and hydrogen phosphate units exist in the structure of beraunite. The series of Raman bands at 567, 582, 601, 644, 661, 673, and 687 cm-1 are assigned to the PO43- ν2 bending modes. The series of Raman bands at 437, 468, 478, 491, 503 cm-1 are attributed to the PO43- and HOPO32- ν4 bending modes. No Raman bands of beraunite which could be attributed to the hydroxyl stretching unit were observed. Infrared bands at 3511 and 3359 cm-1 are ascribed to the OH stretching vibration of the OH units. Very broad bands at 3022 and 3299 cm-1 are attributed to the OH stretching vibrations of water. Vibrational spectroscopy offers insights into the molecular structure of the phosphate mineral beraunite.

Quantification of octacalcium phosphate, authigenic apatite and detrital apatite in coastal sediments using differential dissolution and standard addition

NASA Astrophysics Data System (ADS)

Oxmann, J. F.; Schwendenmann, L.

2014-06-01

Knowledge of calcium phosphate (Ca-P) solubility is crucial for understanding temporal and spatial variations of phosphorus (P) concentrations in water bodies and sedimentary reservoirs. In situ relationships between liquid- and solid-phase levels cannot be fully explained by dissolved analytes alone and need to be verified by determining particular sediment P species. Lack of quantification methods for these species limits the knowledge of the P cycle. To address this issue, we (i) optimized a specifically developed conversion-extraction (CONVEX) method for P species quantification using standard additions, and (ii) simultaneously determined solubilities of Ca-P standards by measuring their pH-dependent contents in the sediment matrix. Ca-P minerals including various carbonate fluorapatite (CFAP) specimens from different localities, fluorapatite (FAP), fish bone apatite, synthetic hydroxylapatite (HAP) and octacalcium phosphate (OCP) were characterized by XRD, Raman, FTIR and elemental analysis. Sediment samples were incubated with and without these reference minerals and then sequentially extracted to quantify Ca-P species by their differential dissolution at pH values between 3 and 8. The quantification of solid-phase phosphates at varying pH revealed solubilities in the following order: OCP > HAP > CFAP (4.5% CO3) > CFAP (3.4% CO3) > CFAP (2.2% CO3) > FAP. Thus, CFAP was less soluble in sediment than HAP, and CFAP solubility increased with carbonate content. Unspiked sediment analyses together with standard addition analyses indicated consistent differential dissolution of natural sediment species vs. added reference species and therefore verified the applicability of the CONVEX method in separately determining the most prevalent Ca-P minerals. We found surprisingly high OCP contents in the coastal sediments analyzed, which supports the hypothesis of apatite formation by an OCP precursor mechanism.

Quantification of octacalcium phosphate, authigenic apatite and detrital apatite in coastal sediments using differential dissolution and standard addition

NASA Astrophysics Data System (ADS)

Oxmann, J. F.; Schwendenmann, L.

2014-01-01

Knowledge of calcium phosphate (Ca-P) solubility is crucial for understanding temporal and spatial variations of phosphorus (P) concentrations in water bodies and sedimentary reservoirs. In-situ relationships between liquid and solid-phase levels cannot be fully explained by dissolved analytes alone and need to be verified by determination of particular sediment P species. Lack of quantification methods for these species limits the knowledge of the P cycle. To address this issue, we (i) optimized a specifically developed conversion-extraction (CONVEX) method for P species quantification using standard additions; and (ii) simultaneously determined solubilities of Ca-P standards by measuring their pH-dependent contents in the sediment matrix. Ca-P minerals including various carbonate fluorapatite (CFAP) specimens from different localities, fluorapatite (FAP), fish bone apatite, synthetic hydroxylapatite (HAP) and octacalcium phosphate (OCP) were characterized by XRD, Raman, FTIR and elemental analysis. Sediment samples were incubated with and without these reference minerals and then sequentially extracted to quantify Ca-P species by their differential dissolution at pH values between 3 and 8. The quantification of solid-phase phosphates at varying pH revealed solubilities in the following order: OCP > HAP > CFAP (4.5% CO3) > CFAP (3.4% CO3) > CFAP (2.2% CO3) > FAP. Thus, CFAP was less soluble in sediment than HAP, and CFAP solubility increased with carbonate content. Unspiked sediment analyses together with standard addition analyses indicated consistent differential dissolution of natural sediment species vs. added reference species and therefore verified the applicability of the CONVEX method in separately determining the most prevalent Ca-P minerals. We found surprisingly high OCP contents in the analyzed coastal sediments which supports the hypothesis of apatite formation by an OCP precursor.

Regulatory inhibition of biological tissue mineralization by calcium phosphate through post-nucleation shielding by fetuin-A

NASA Astrophysics Data System (ADS)

Chang, Joshua C.; Miura, Robert M.

2016-04-01

In vertebrates, insufficient availability of calcium and inorganic phosphate ions in extracellular fluids leads to loss of bone density and neuronal hyper-excitability. To counteract this problem, calcium ions are usually present at high concentrations throughout bodily fluids—at concentrations exceeding the saturation point. This condition leads to the opposite situation where unwanted mineral sedimentation may occur. Remarkably, ectopic or out-of-place sedimentation into soft tissues is rare, in spite of the thermodynamic driving factors. This fortunate fact is due to the presence of auto-regulatory proteins that are found in abundance in bodily fluids. Yet, many important inflammatory disorders such as atherosclerosis and osteoarthritis are associated with this undesired calcification. Hence, it is important to gain an understanding of the regulatory process and the conditions under which it can go awry. In this manuscript, we extend mean-field continuum classical nucleation theory of the growth of clusters to encompass surface shielding. We use this formulation to study the regulation of sedimentation of calcium phosphate salts in biological tissues through the mechanism of post-nuclear shielding of nascent mineral particles by binding proteins. We develop a mathematical description of this phenomenon using a countable system of hyperbolic partial differential equations. A critical concentration of regulatory protein is identified as a function of the physical parameters that describe the system.

Regulatory inhibition of biological tissue mineralization by calcium phosphate through post-nucleation shielding by fetuin-A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Joshua C., E-mail: joshchang@ucla.edu; Miura, Robert M., E-mail: miura@njit.edu

In vertebrates, insufficient availability of calcium and inorganic phosphate ions in extracellular fluids leads to loss of bone density and neuronal hyper-excitability. To counteract this problem, calcium ions are usually present at high concentrations throughout bodily fluids—at concentrations exceeding the saturation point. This condition leads to the opposite situation where unwanted mineral sedimentation may occur. Remarkably, ectopic or out-of-place sedimentation into soft tissues is rare, in spite of the thermodynamic driving factors. This fortunate fact is due to the presence of auto-regulatory proteins that are found in abundance in bodily fluids. Yet, many important inflammatory disorders such as atherosclerosis andmore » osteoarthritis are associated with this undesired calcification. Hence, it is important to gain an understanding of the regulatory process and the conditions under which it can go awry. In this manuscript, we extend mean-field continuum classical nucleation theory of the growth of clusters to encompass surface shielding. We use this formulation to study the regulation of sedimentation of calcium phosphate salts in biological tissues through the mechanism of post-nuclear shielding of nascent mineral particles by binding proteins. We develop a mathematical description of this phenomenon using a countable system of hyperbolic partial differential equations. A critical concentration of regulatory protein is identified as a function of the physical parameters that describe the system.« less

Mineral Ecology: Surface Specific Colonization and Geochemical Drivers of Biofilm Accumulation, Composition, and Phylogeny

PubMed Central

Jones, Aaron A.; Bennett, Philip C.

2017-01-01

This study tests the hypothesis that surface composition influences microbial community structure and growth of biofilms. We used laboratory biofilm reactors (inoculated with a diverse subsurface community) to explore the phylogenetic and taxonomic variability in microbial communities as a function of surface type (carbonate, silicate, aluminosilicate), media pH, and carbon and phosphate availability. Using high-throughput pyrosequencing, we found that surface type significantly controlled ~70–90% of the variance in phylogenetic diversity regardless of environmental pressures. Consistent patterns also emerged in the taxonomy of specific guilds (sulfur-oxidizers/reducers, Gram-positives, acidophiles) due to variations in media chemistry. Media phosphate availability was a key property associated with variation in phylogeny and taxonomy of whole reactors and was negatively correlated with biofilm accumulation and α-diversity (species richness and evenness). However, mineral-bound phosphate limitations were correlated with less biofilm. Carbon added to the media was correlated with a significant increase in biofilm accumulation and overall α-diversity. Additionally, planktonic communities were phylogenetically distant from those in biofilms. All treatments harbored structurally (taxonomically and phylogenetically) distinct microbial communities. Selective advantages within each treatment encouraged growth and revealed the presence of hundreds of additional operational taxonomix units (OTU), representing distinct consortiums of microorganisms. Ultimately, these results provide evidence that mineral/rock composition significantly influences microbial community structure, diversity, membership, phylogenetic variability, and biofilm growth in subsurface communities. PMID:28400754

Attenuation and Transport Mechanisms of Depleted Uranium in Groundwater at Lawrence Livermore National Laboratory Site 300

NASA Astrophysics Data System (ADS)

Danny, K. R.; Taffet, M. J.; Brusseau, M. L. L.; Chorover, J.

2015-12-01

Lawrence Livermore National Laboratory (LLNL) Site 300 was established in 1955 to support weapons research and development. Depleted uranium was used as a proxy for fissile uranium-235 (235U) in open-air explosives tests conducted at Building 812. As a result, oxidized depleted uranium was deposited on the ground, eventually migrating to the underlying sandstone aquifer. Uranium (U) groundwater concentrations exceed the California and Federal Maximum Contaminant Level of 20 pCi L-1 (30 ug L-1). However, the groundwater plume appears to attenuate within 60 m of the source, beyond which no depleted U is detected. This study will determine the relative contribution of physical (e.g. dilution), chemical (e.g. surface adsorption, mineral precipitation), and biological (e.g. biotransformation) processes that contribute to the apparent attenuation of U, which exists as uranyl (UO22+) complexes, at the site. Methods of investigation include evaluating 15 yr of hydrogeologic and chemical data, creating a site conceptual model, and applying equilibrium (e.g. aqueous species complexation, mineral saturation indices) and reactive transport models using Geochemist's WorkbenchTM. Reactive transport results are constrained by direct field observations, including U major ion, and dissolved O2 concentrations, pH, and others, under varying chemical and hydraulic conditions. Aqueous speciation calculations indicate that U primarily exists as anionic CaUO2(CO3)32- or neutral Ca2UO2(CO3)30 species. Additionally, nucleation and growth of Ca/Mg uranyl carbonate solids are predicted to affect attenuation. Initial reactive transport results suggest surface adsorption (e.g. ion exchange, surface complexation) to layer silicate clays is limited under the aqueous geochemical conditions of the site. Current and future work includes XRD analysis of aquifer solids to constrain iron and aluminum (oxy)hydroxides, and coupling advective-dispersive transport with the chemical and physical processes. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-675707.

CONTINUOUS PRECIPITATION METHOD FOR CONVERSION OF URANYL NITRATE TO URANIUM HEXAFLUORIDE

DOEpatents

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

1962-11-13

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

On the origin of the cation templated self-assembly of uranyl-peroxide nanoclusters.

PubMed

Miró, Pere; Pierrefixe, Simon; Gicquel, Mickaël; Gil, Adrià; Bo, Carles

2010-12-22

Uranyl-peroxide nanoclusters display different topologies based on square, pentagonal and hexagonal building blocks. Computed complexation energies of different cations (Li(+), Na(+), K(+), Rb(+), and Cs(+)) with [UO(2)(O(2))(H(2)O)](n) (n = 4, 5, and 6) macrocycles suggest a strong cation templating effect. The inherent bent structure of a U-O(2)-U model dimer is demonstrated and justified through the analysis of its electronic structure, as well as of the inherent curvature of the four-, five-, and six-uranyl macrocyles. The curvature is enhaced by cation coordination, which is suggested to be the driving force for the self-assembly of the nanocapsules.

ANALYTICAL METHOD FOR THE DETERMINATION OF BORON IN URANYL NITRATE SOLUTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1962-01-01

A method was developed for the determination of boron in uranyl nitrate solutions. The boron is separated from uranium and other impurities by distillation of methyl borate. It is determined absorptiometrically by means of curcumin in the presence of orthochlorophenol, perchloric acid, and acetic anhydride. The limit of detection is judged to be not greater than 0.05 mu g, but is dependent on the purity of the reagents used. The coefficient of variation on 210 results at the 0.2 mu g boron level was 26% with a bias of -25%. The method may be applied to depleted uranyl nitrate solutionsmore » and uranium slag recovery liquors. (auth)« less

The Rachitic Tooth

PubMed Central

Nociti, Francisco H.; Somerman, Martha J.

2014-01-01

Teeth are mineralized organs composed of three unique hard tissues, enamel, dentin, and cementum, and supported by the surrounding alveolar bone. Although odontogenesis differs from osteogenesis in several respects, tooth mineralization is susceptible to similar developmental failures as bone. Here we discuss conditions fitting under the umbrella of rickets, which traditionally referred to skeletal disease associated with vitamin D deficiency but has been more recently expanded to include newly identified factors involved in endocrine regulation of vitamin D, phosphate, and calcium, including phosphate-regulating endopeptidase homolog, X-linked, fibroblast growth factor 23, and dentin matrix protein 1. Systemic mineral metabolism intersects with local regulation of mineralization, and factors including tissue nonspecific alkaline phosphatase are necessary for proper mineralization, where rickets can result from loss of activity of tissue nonspecific alkaline phosphatase. Individuals suffering from rickets often bear the additional burden of a defective dentition, and transgenic mouse models have aided in understanding the nature and mechanisms involved in tooth defects, which may or may not parallel rachitic bone defects. This report reviews dental effects of the range of rachitic disorders, including discussion of etiologies of hereditary forms of rickets, a survey of resulting bone and tooth mineralization disorders, and a discussion of mechanisms, known and hypothesized, involved in the observed dental pathologies. Descriptions of human pathology are augmented by analysis of transgenic mouse models, and new interpretations are brought to bear on questions of how teeth are affected under conditions of rickets. In short, the rachitic tooth will be revealed. PMID:23939820

PHOSPHO1 is essential for mechanically competent mineralization and the avoidance of spontaneous fractures

PubMed Central

Huesa, Carmen; Yadav, Manisha C.; Finnilä, Mikko A.J.; Goodyear, Simon R.; Robins, Simon P.; Tanner, K. Elizabeth; Aspden, Richard M.; Millán, José Luis; Farquharson, Colin

2011-01-01

Phosphatases are essential for the mineralization of the extracellular matrix within the skeleton. Their precise identities and functions however remain unclear. PHOSPHO1 is a phosphoethanolamine/phosphocholine phosphatase involved in the generation of inorganic phosphate for bone mineralization. It is highly expressed at sites of mineralization in bone and cartilage. The bones of Phospho1−/− mice are hypomineralized, bowed and present with spontaneous greenstick fractures at birth. In this study we show that PHOSPHO1 is essential for mechanically competent mineralization that is able to withstand habitual load. Long bones from Phospho1−/− mice did not fracture during 3- point bending but deformed plastically. With dynamic loading nanoindentation the elastic modulus and hardness of Phospho1−/− tibiae were significantly lower than wild-type tibia. Raman microscopy revealed significantly lower mineral:matrix ratios and lower carbonate substitutions in Phospho1−/− tibia. The altered dihydroxylysinonorleucine/hydroxyllysinonorleucine and pyridoline/deoxypyridinoline collagen crosslink ratios indicated possible changes in lysyl hydroxylase-1 activity and/or bone mineralization status. The bone formation and resorption markers, N-terminal propeptide and C-terminal telopeptide of Type I collagen, were both increased in Phospho1−/− mice and this we associated with increased bone remodelling during fracture repair or an attempt to remodel a mechanically competent bone capable of withstanding physiological load. In summary these data indicate that Phospho1−/− bones are hypomineralized and, consequently, are softer and more flexible. An inability to withstand physiological loading may explain the deformations noted. We hypothesize that this phenotype is due to the reduced availability of inorganic phosphate to form hydroxyapatite during mineralization, creating an undermineralized yet active bone. PMID:21272676

Tolerance Induction of Temperature and Starvation with Tricalcium Phosphate on Preservation and Sporulation in Bacillus amyloliquefaciens Detected by Flow Cytometry.

PubMed

Shahrokh Esfahani, Samaneh; Emtiazi, Giti; Shafiei, Rasoul; Ghorbani, Najmeh; Zarkesh Esfahani, Seyed Hamid

2016-09-01

The Bacillus species have many applications in the preparation of various enzymes, probiotic, biofertilizer, and biomarkers for which the survival of resting cells and spore formation under different conditions are important. In this study, water and saline along with different mineral substances such as calcium carbonate, calcium phosphate, and silica were used for the detection of survival and preservation of Bacillus amyloliquefaciens. The results showed intensive death of resting cells at 8 °C, but significant survival at 28 °C after one month. However, preservation by minerals significantly decreased the rate of death and induced sporulation at both the temperatures. The resting cells were maintained at room temperature (about 60 % of the initial population survived after a month) in the presence of tricalcium phosphate. The results showed that temperature has more effect on sporulation compare with starvation. The sporulation in normal saline at 28 °C was 70 times more than that at 8 °C; meanwhile, addition of tricalcium phosphate increases sporulation by 90 times. Also, the FTIR data showed the interaction of tricalcium phosphate with spores and resting cells. The discrimination of sporulation from non-sporulation state was performed by nucleic acid staining with thiazole orange and detected by flow cytometry. The flow cytometric studies confirmed that the rates of sporulation in pure water were significantly more at 28 °C. This is the first report on the detection of bacterial spore with thiazole orange by flow cytometry and also on the interaction of tricalcium phosphate with spores by FTIR analyses.

Micro-x-ray fluorescence, micro-x-ray absorption spectroscopy, and micro-x-ray diffraction investigation of lead speciation after the addition of different phosphorus amendments to a smelter-contaminated soil.

PubMed

Baker, Lucas R; Pierzynski, Gary M; Hettiarachchi, Ganga M; Scheckel, Kirk G; Newville, Matthew

2014-03-01

The stabilization of Pb on additions of P to contaminated soils and mine spoil materials has been well documented. It is clear from the literature that different P sources result in different efficacies of Pb stabilization in the same contaminated material. We hypothesized that the differences in the efficacy of Pb stabilization in contaminated soils on fluid or granular P amendment addition is due to different P reaction processes in and around fertilizer granules and fluid droplets. We used a combination of several synchrotron-based techniques (i.e., spatially resolved micro-X-ray fluorescence, micro-X-ray absorption near-edge structure spectroscopy, and micro-X-ray diffraction) to speciate Pb at two incubation times in a smelter-contaminated soil on addition of several fluid and granular P amendments. The results indicated that the Pb phosphate mineral plumbogummite was an intermediate phase of pyromorphite formation. Additionally, all fluid and granular P sources were able to induce Pb phosphate formation, but fluid phosphoric acid (PA) was the most effective with time and distance from the treatment. Granular phosphate rock and triple super phosphate (TSP) amendments reacted to generate Pb phosphate minerals, with TSP being more effective at greater distances from the point of application. As a result, PA and TSP were the most effective P amendments at inducing Pb phosphate formation, but caution needs to be exercised when adding large amounts of soluble P to the environment. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Influences of bicarbonate on processes of enamel subsurface remineralization and demineralization: assessment using micro-Raman spectroscopy and transverse microradiography.

PubMed

Kuramochi, Erika; Iizuka, Junko; Mukai, Yoshiharu

2016-12-01

In the present study, we investigated, using micro-Raman spectroscopy (Raman) and transverse microradiography, the influence of bicarbonate [sodium hydrogen carbonate (NaHCO 3 )] on the effects of carbonate ions in the mineral phase during demineralization (acid resistance test) of subsurface lesions. Baseline lesions were created by demineralizing bovine enamel, and specimens were then exposed to remineralization solutions containing 0, 5, or 50 mM bicarbonate. Acid resistance tests were performed on remineralized and sound enamel specimens. Raman spectra showed that carbonate and phosphate were incorporated into both surface layers and lesion bodies during remineralization in the presence of bicarbonate. Moreover, the presence of bicarbonate did not affect the rates of remineralization, although the average mineral profiles of remineralized enamel differed from those of sound enamel after acid resistance tests. Raman analyses enabled close evaluation of site-specific characteristics of carbonate and phosphate in subsurface lesions. In conclusion, incorporation of carbonate and phosphate ions into enamel subsurface lesions during remineralization does not affect the magnitude of remineralization or acid resistance. © 2016 Eur J Oral Sci.

Calcium phosphate stabilization of fly ash with chloride extraction.

PubMed

Nzihou, Ange; Sharrock, Patrick

2002-01-01

Municipal solid waste incinerator by products include fly ash and air pollution control residues. In order to transform these incinerator wastes into reusable mineral species, soluble alkali chlorides must be separated and toxic trace elements must be stabilized in insoluble form. We show that alkali chlorides can be extracted efficiently in an aqueous extraction step combining a calcium phosphate gel precipitation. In such a process, sodium and potassium chlorides are obtained free from calcium salts, and the trace metal ions are immobilized in the calcium phosphate matrix. Moderate calcination of the chemically treated fly ash leads to the formation of cristalline hydroxylapatite. Fly ash spiked with copper ions and treated by this process shows improved stability of metal ions. Leaching tests with water or EDTA reveal a significant drop in metal ion dissolution. Hydroxylapatite may trap toxic metals and also prevent their evaporation during thermal treatments. Incinerator fly ash together with air pollution control residues, treated by the combined chloride extraction and hydroxylapatite formation process may be considered safe to use as a mineral filler in value added products such as road base or cement blocks.

Just-in-time vaccines: Biomineralized calcium phosphate core-immunogen shell nanoparticles induce long-lasting CD8+ T cell responses in mice

PubMed Central

Zhou, Weibin; Moguche, Albanus; Chiu, David; Murali-Krishna, Kaja; Baneyx, François

2014-01-01

Distributed and on-demand vaccine production could be game-changing for infectious disease treatment in the developing world by providing new therapeutic opportunities and breaking the refrigeration “cold chain”. Here, we show that a fusion protein between a calcium phosphate binding domain and the model antigen ovalbumin can mineralize a biocompatible adjuvant in a single step. The resulting 50 nm calcium phosphate core-immunogen shell particles are comparable to soluble protein in inducing ovalbumin-specific antibody response and class switch recombination in mice. However, single dose vaccination with nanoparticles leads to higher expansion of ovalbumin-specific CD8+ T cells upon challenge with an influenza virus bearing the ovalbumin-derived SIINFEKL peptide, and these cells produce high levels of IFN-γ. Furthermore, mice exhibit a robust antigen-specific CD8+ T cell recall response when challenged with virus 8 months post-immunization. These results underscore the promise of immunogen-controlled adjuvant mineralization for just-in-time manufacturing of effective T cell vaccines. PMID:24275478

ELECTROLYTIC PREPARATION OF UF$sub 4$

DOEpatents

Allen, A.L.; Anderson, R.W.; Powell, E.W.

1958-11-01

A method is presented for converting hexavalent aranium to uranium tetrafluoride. The method consists of electrolyzing a solution of uranyl fluoride in hydrofluoric acld at about 90 icient laborato C. The uranyl ions are reduced at the cathode and a hydrated uranium tetrafluoride precipitates. The precipitate is separated and subsequently dehydrated to UF/sub 4/.

Immunogold Staining of Ultrathin Thawed Cryosections for Transmission Electron Microscopy (TEM).

PubMed

Skepper, Jeremy N; Powell, Janet M

2008-06-01

INTRODUCTIONA pre-embedding method of immunochemical staining is used if antigens are damaged by resin embedding, or if the best preservation of membranes is required. Applying immunogold reagents to sections of lightly fixed tissue, free of embedding medium, can be a very sensitive method of immunochemical staining. Cells or tissues are fixed as strongly as possible and then treated with a cryoprotectant, which is usually a mixture of sucrose and polyvinylpyrrolidone (PVP). They are frozen onto pins in liquid nitrogen and sectioned at approximately -100°C. The frozen sections are thaw-mounted on to Formvar/nickel film grids and the cryoprotectant is removed by floating the grids on drops of phosphate-buffered saline (PBS). The immunogold staining is performed on the unembedded sections, which are subsequently contrast counterstained and infiltrated with a mixture of methylcellulose and uranyl acetate. In this protocol, samples are sectioned at low temperature, thaw-mounted onto film grids, immunochemically stained, contrast counterstained, and embedded/encapsulated in situ on the grid before viewing by transmission electron microscopy (TEM).