Determination of Thermodynamic Properties of Alkaline Earth-liquid Metal Alloys Using the Electromotive Force Technique

PubMed Central

Nigl, Thomas P.; Smith, Nathan D.; Lichtenstein, Timothy; Gesualdi, Jarrod; Kumar, Kuldeep; Kim, Hojong

2017-01-01

A novel electrochemical cell based on a CaF2 solid-state electrolyte has been developed to measure the electromotive force (emf) of binary alkaline earth-liquid metal alloys as functions of both composition and temperature in order to acquire thermodynamic data. The cell consists of a chemically stable solid-state CaF2-AF2 electrolyte (where A is the alkaline-earth element such as Ca, Sr, or Ba), with binary A-B alloy (where B is the liquid metal such as Bi or Sb) working electrodes, and a pure A metal reference electrode. Emf data are collected over a temperature range of 723 K to 1,123 K in 25 K increments for multiple alloy compositions per experiment and the results are analyzed to yield activity values, phase transition temperatures, and partial molar entropies/enthalpies for each composition. PMID:29155770

Trace Elemental Imaging of Rare Earth Elements Discriminates Tissues at Microscale in Flat Fossils

PubMed Central

Gueriau, Pierre; Mocuta, Cristian; Dutheil, Didier B.; Cohen, Serge X.; Thiaudière, Dominique; Charbonnier, Sylvain; Clément, Gaël; Bertrand, Loïc

2014-01-01

The interpretation of flattened fossils remains a major challenge due to compression of their complex anatomies during fossilization, making critical anatomical features invisible or hardly discernible. Key features are often hidden under greatly preserved decay prone tissues, or an unpreparable sedimentary matrix. A method offering access to such anatomical features is of paramount interest to resolve taxonomic affinities and to study fossils after a least possible invasive preparation. Unfortunately, the widely-used X-ray micro-computed tomography, for visualizing hidden or internal structures of a broad range of fossils, is generally inapplicable to flattened specimens, due to the very high differential absorbance in distinct directions. Here we show that synchrotron X-ray fluorescence spectral raster-scanning coupled to spectral decomposition or a much faster Kullback-Leibler divergence based statistical analysis provides microscale visualization of tissues. We imaged exceptionally well-preserved fossils from the Late Cretaceous without needing any prior delicate preparation. The contrasting elemental distributions greatly improved the discrimination of skeletal elements material from both the sedimentary matrix and fossilized soft tissues. Aside content in alkaline earth elements and phosphorus, a critical parameter for tissue discrimination is the distinct amounts of rare earth elements. Local quantification of rare earths may open new avenues for fossil description but also in paleoenvironmental and taphonomical studies. PMID:24489809

Trace elemental imaging of rare earth elements discriminates tissues at microscale in flat fossils.

PubMed

Gueriau, Pierre; Mocuta, Cristian; Dutheil, Didier B; Cohen, Serge X; Thiaudière, Dominique; Charbonnier, Sylvain; Clément, Gaël; Bertrand, Loïc

2014-01-01

The interpretation of flattened fossils remains a major challenge due to compression of their complex anatomies during fossilization, making critical anatomical features invisible or hardly discernible. Key features are often hidden under greatly preserved decay prone tissues, or an unpreparable sedimentary matrix. A method offering access to such anatomical features is of paramount interest to resolve taxonomic affinities and to study fossils after a least possible invasive preparation. Unfortunately, the widely-used X-ray micro-computed tomography, for visualizing hidden or internal structures of a broad range of fossils, is generally inapplicable to flattened specimens, due to the very high differential absorbance in distinct directions. Here we show that synchrotron X-ray fluorescence spectral raster-scanning coupled to spectral decomposition or a much faster Kullback-Leibler divergence based statistical analysis provides microscale visualization of tissues. We imaged exceptionally well-preserved fossils from the Late Cretaceous without needing any prior delicate preparation. The contrasting elemental distributions greatly improved the discrimination of skeletal elements material from both the sedimentary matrix and fossilized soft tissues. Aside content in alkaline earth elements and phosphorus, a critical parameter for tissue discrimination is the distinct amounts of rare earth elements. Local quantification of rare earths may open new avenues for fossil description but also in paleoenvironmental and taphonomical studies.

Process for preparing higher oxides of the alkali and alkaline earth metals

NASA Technical Reports Server (NTRS)

Sadhukhan, P.; Bell, A. (Inventor)

1978-01-01

High purity inorganic higher oxides of the alkali and alkaline earth metals are prepared by subjecting the hydroxide of the alkali and alkaline earth metal to a radio frequency discharge sustained in oxygen. The process is particulary adaptable to the production of high purity potassium superoxide by subjecting potassium hydroxide to glow discharge sustained in oxygen under the pressure of about 0.75 to 1.00 torr.

Diclofenac salts. III. Alkaline and earth alkaline salts.

PubMed

Fini, Adamo; Fazio, Giuseppe; Rosetti, Francesca; Angeles Holgado, M; Iruín, Ana; Alvarez-Fuentes, Josefa

2005-11-01

Diclofenac salts containing the alkaline and two earth alkaline cations have been prepared and characterized by scanning electron microscopy (SEM) and EDAX spectroscopy; and by thermal and thermogravimetric analysis (TGA): all of them crystallize as hydrate when precipitated from water. The salts dehydrate at room temperature and more easily on heating, but recovery the hydration, when placed in a humid environment. X-ray diffraction spectra suggest that on dehydration new peaks appear on diffractograms and the lattice of the salts partially looses crystallinity. This phenomenon is readily visible in the case of the calcium and magnesium salts, whose thermograms display a crystallization exotherm, before melting or decomposing at temperatures near or above 200 degrees C; these last salts appear to form solvates, when prepared from methanol. The thermogram of each salt shows a complex endotherm of dehydration about 100 degrees C; the calcium salt displays two endotherms, well separated at about 120 and 160 degrees C, which disappear after prolonged heating. Decomposition exotherms, before or soon after the melting, appear below 300 degrees C. The ammonium salt is thermally unstable and, when heated to start dehydration, dissociates and leaves acidic diclofenac.

Ab initio study of the alkali and alkaline-earth monohydroxides

NASA Technical Reports Server (NTRS)

Bauschlicher, C. W., Jr.; Langhoff, S. R.; Partridge, H.

1986-01-01

A systematic study of the structures and dissociation energies of all the alkali and alkaline-earth monohydroxides is conducted. A theoretical model for determining accurate dissociation energies of ionic molecules is discussed. The obtained theoretical structures and dissociation energies of the alkali and alkaline-earth monohydroxides, respectively, are compared with experimental data. It is found that the theoretical studies of the bending potentials of BeOH, MgOH, and CaOH reveal the different admixture of covalent character in these systems. The BeOH molecule with the largest degree of covalent character is found to be bent (theta equals 147 deg). The MgOH is also linear. The theoretical dissociation energies for the alkali and akaline-earth hydroxides are thought to be accurate to 0.1 eV.

Temperature Dependence of Mineral Solubility in Water. Part 3. Alkaline and Alkaline Earth Sulfates

NASA Astrophysics Data System (ADS)

Krumgalz, B. S.

2018-06-01

The databases of alkaline and alkaline earth sulfate solubilities in water at various temperatures were created using experimental data from the publications over about the last two centuries. Statistical critical evaluation of the created databases was produced since there were enough independent data sources to justify such evaluation. The reliable experimental data were adequately described by polynomial expressions over various temperature ranges. Using the Pitzer approach for ionic activity and osmotic coefficients, the thermodynamic solubility products for the discussed minerals have been calculated at various temperatures and represented by polynomial expressions.

Temperature Dependence of Mineral Solubility in Water. Part 2. Alkaline and Alkaline Earth Bromides

NASA Astrophysics Data System (ADS)

Krumgalz, B. S.

2018-03-01

Databases of alkaline and alkaline earth bromide solubilities in water at various temperatures were created using experimental data from publications over about the last two centuries. Statistical critical evaluation of the created databases was produced since there were enough independent data sources to justify such evaluation. The reliable experimental data were adequately described by polynomial expressions over various temperature ranges. Using the Pitzer approach for ionic activity and osmotic coefficients, the thermodynamic solubility products for the discussed bromide minerals have been calculated at various temperature intervals and also represented by polynomial expressions.

When VSEPR Fails: Experimental and Theoretical Investigations of the Behavior of Alkaline-Earth-Metal Acetylides

PubMed Central

Guino-o, Marites A.; Alexander, Jacob S.; McKee, Michael L.; Hope, Håkon; Englich, Ulrich B.

2014-01-01

The synthesis, structural, and spectral characterization as well as a theoretical study of a family of alkaline-earth-metal acetylides provides insights into synthetic access and the structural and bonding characteristics of this group of highly reactive compounds. Based on our earlier communication that reported unusual geometry for a family of triphenylsilyl-substituted alkaline-earth-metal acetylides, we herein present our studies on an expanded family of target derivatives, providing experimental and theoretical data to offer new insights into the intensively debated theme of structural chemistry in heavy alkaline-earth-metal chemistry. PMID:19844925

Adsorption of alkali and alkaline earth metal atoms and dimers on monolayer germanium carbide

NASA Astrophysics Data System (ADS)

Gökçe, Aytaç Gürhan; Ersan, Fatih

2017-01-01

First-principles plane wave calculations have been performed to study the adsorption of alkali and alkaline earth metals on monolayer germanium carbide (GeC). We found that the favourable adsorption sites on GeC sheet for single alkali and alkaline earth adatoms are generally different from graphene or germanene. Among them, Mg, Na and their dimers have weakly bounded to GeC due to their closed valence electron shells, so they may have high mobility on GeC. Two different levels of adatom coverage (? and ?) have been investigated and we concluded that different electronic structures and magnetic moments for both coverages owing to alkali and alkaline earth atoms have long range electrostatic interactions. Lithium atom prefers to adsorbed on hollow site similar to other group-IV monolayers and the adsorption results in metallisation of GeC instead of semiconducting behaviour. Na and K adsorption can induce 1 ? total magnetic moment on GeC structures and they have shown semiconductor property which may have potential use in spintronic devices. We also showed that alkali or alkaline earth metal atoms can form dimer on GeC sheet. Calculated adsorption energies suggest that clustering of alkali and alkaline earth atoms is energetically favourable. All dimer adsorbed GeC systems have nonmagnetic semiconductor property with varying band gaps from 0.391 to 1.311 eV which are very suitable values for various device applications.

Recent advances in rare earth doped alkali-alkaline earth borates for solid state lighting applications

NASA Astrophysics Data System (ADS)

Verma, Shefali; Verma, Kartikey; Kumar, Deepak; Chaudhary, Babulal; Som, Sudipta; Sharma, Vishal; Kumar, Vijay; Swart, Hendrik C.

2018-04-01

As a novel class of inorganic phosphor, the alkali-alkaline earth borate phosphors have gained huge attention due to their charming applications in solid-state lighting (SSL) and display devices. The current research drive shows that phosphors based on the alkali-alkaline earth borates have transformed the science and technology due to their high transparency over a broad spectral range, their flexibility in structure and durability for mechanical and high-laser applications. Recent advances in various aspects of rare-earth (RE) doped borate based phosphors and their utilizations in SSL and light emitting diodes are summarized in this review article. Moreover, the present status and upcoming scenario of RE-doped borate phosphors were reviewed in general along with the proper credential from the existing literature. It is believed that this review is a sole compilation of crucial information about the RE-doped borate phosphors in a single platform.

Unified mechanism of alkali and alkaline earth catalyzed gasification reactions of carbon by CO2 and H2O

USGS Publications Warehouse

Chen, S.G.; Yang, R.T.

1997-01-01

From molecular orbital calculations, a unified mechanism is proposed for the gasification reactions of graphite by CO2 and H2O, both uncatalyzed and catalyzed by alkali and alkaline earth catalysts. In this mechanism, there are two types of oxygen intermediates that are bonded to the active edge carbon atoms: an in-plane semiquinone type, Cf(O), and an off-plane oxygen bonded to two saturated carbon atoms that are adjacent to the semiquinone species, C(O)Cf(O). The rate-limiting step is the decomposition of these intermediates by breaking the C-C bonds that are connected to Cf(O). A new rate equation is derived for the uncatalyzed reactions, and that for the catalyzed reactions is readily available from the proposed mechanism. The proposed mechanism can account for several unresolved experimental observations: TPD and TK (transient kinetics) desorption results of the catalyzed systems, the similar activation energies for the uncatalyzed and catalyzed reactions, and the relative activities of the alkali and alkaline earth elements. The net charge of the edge carbon active site is substantially changed by gaining electron density from the alkali or alkaline earth element (by forming C-O-M, where M stands for metal). The relative catalytic activities of these elements can be correlated with their abilities of donating electrons and changing the net charge of the edge carbon atom. As shown previously (Chen, S. G.; Yang, R. T. J. Catal. 1993, 141, 102), only clusters of the alkali compounds are active. This derives from the ability of the clusters to dissociate CO2 and H2O to form O atoms and the mobility of the dissociated O atoms facilitated by the clusters.

Charge-separated and molecular heterobimetallic rare earth-rare earth and alkaline earth-rare earth aryloxo complexes featuring intramolecular metal-pi-arene interactions.

PubMed

Deacon, Glen B; Junk, Peter C; Moxey, Graeme J; Ruhlandt-Senge, Karin; St Prix, Courtney; Zuniga, Maria F

2009-01-01

Treatment of a rare earth metal (Ln) and a potential divalent rare earth metal (Ln') or an alkaline earth metal (Ae) with 2,6-diphenylphenol (HOdpp) at elevated temperatures (200-250 degrees C) afforded heterobimetallic aryloxo complexes, which were structurally characterised. A charge-separated species [(Ln'/Ae)(2)(Odpp)(3)][Ln(Odpp)(4)] was obtained for a range of metals, demonstrating the similarities between the chemistry of the divalent rare earth metals and the alkaline earth metals. The [(Ln'/Ae)(2)(Odpp)(3)](+) cation in the heterobimetallic structures is unusual in that it consists solely of bridging aryloxide ligands. A molecular heterobimetallic species [AeEu(Odpp)(4)] (Ae = Ca, Sr, Ba) was obtained by treating an alkaline earth metal and Eu metal with HOdpp at elevated temperatures. Similarly, [BaSr(Odpp)(4)] was prepared by treating Ba metal and Sr metal with HOdpp. Treatment of [Ba(2)(Odpp)(4)] with [Mg(Odpp)(2)(thf)(2)] in toluene afforded [Ba(2)(Odpp)(3)][Mg(Odpp)(3)(thf)]. Analogous solution-based syntheses were not possible for [(Ln'/Ae)(2)(Odpp)(3)][Ln(Odpp)(4)] complexes, for which the free-metal route was essential. As a result of the absence of additional donor ligands, the crystal structures of the heterobimetallic complexes feature extensive pi-Ph-metal interactions involving the pendant phenyl groups of the Odpp ligands, thus enabling the large electropositive metal atoms to attain coordination saturation. The charge-separated heterobimetallic species were purified by extraction with toluene/thf mixtures at ambient temperature (Ba-containing compounds) or by extraction with toluene under pressure above the boiling point of the solvent (other products). In donor solvents, heterobimetallic complexes other than those containing barium were found to fragment into homometallic species.

Energetics of alkali and alkaline earth ion-exchanged zeolite A

DOE PAGES

Sun, Hui; Wu, Di; Liu, Kefeng; ...

2016-06-30

Alkali and alkaline earth ion-exchanged zeolite A samples were synthesized in aqueous exchange media. They were thoroughly studied by powder X-ray diffraction (XRD), electron microprobe (EMPA), thermogravimetric analysis and differential scanning calorimetry (TG-DSC), and high temperature oxide melt solution calorimetry. The hydration energetics and enthalpies of formation of these zeolite A materials from constituent oxides were determined. Specifically, the hydration level of zeolite A has a linear dependence on the average ionic potential ( Z/r) of the cation, from 0.894 (Rb-A) to 1.317 per TO 2 (Mg-A). The formation enthalpies from oxides (25 °C) range from –93.71 ± 1.77 (K-A)more » to –48.02 ± 1.85 kJ/mol per TO 2 (Li-A) for hydrated alkali ion-exchanged zeolite A, and from –47.99 ± 1.20 (Ba-A) to –26.41 ± 1.71 kJ/mol per TO 2 (Mg-A) for hydrated alkaline earth ion-exchanged zeolite A. As a result, the formation enthalpy from oxides generally becomes less exothermic as Z/r increases, but a distinct difference in slope is observed between the alkali and the alkaline earth series.« less

Oxidation catalysts on alkaline earth supports

DOEpatents

Mohajeri, Nahid

2017-03-21

An oxidation catalyst includes a support including particles of an alkaline earth salt, and first particles including a palladium compound on the support. The oxidation catalyst can also include precious metal group (PMG) metal particles in addition to the first particles intermixed together on the support. A gas permeable polymer that provides a continuous phase can completely encapsulate the particles and the support. The oxidation catalyst may be used as a gas sensor, where the first particles are chemochromic particles.

Alkaline earth cation extraction from acid solution

DOEpatents

Dietz, Mark; Horwitz, E. Philip

2003-01-01

An extractant medium for extracting alkaline earth cations from an aqueous acidic sample solution is described as are a method and apparatus for using the same. The separation medium is free of diluent, free-flowing and particulate, and comprises a Crown ether that is a 4,4'(5')[C.sub.4 -C.sub.8 -alkylcyclohexano]18-Crown-6 dispersed on an inert substrate material.

Electric dipole moments and chemical bonding of diatomic alkali-alkaline earth molecules.

PubMed

Pototschnig, Johann V; Hauser, Andreas W; Ernst, Wolfgang E

2016-02-17

We investigate the properties of alkali-alkaline earth diatomic molecules in the lowest Σ(+) states of the doublet and quartet multiplicity by ab initio calculations. In all sixteen cases studied, the permanent electric dipole moment points in opposite directions for the two spin states. This peculiarity can be explained by molecular orbital theory. We further discuss dissociation energies and bond distances. We analyze trends and provide an empirically motivated model for the prediction of the permanent electric dipole moment for combinations of alkali and alkaline earth atoms not studied in this work.

Theoretical study of the alkali and alkaline-earth monosulfides

NASA Technical Reports Server (NTRS)

Partridge, Harry; Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.

1988-01-01

Ab initio calculations have been used to obtain accurate spectroscopic constants for the X2Pi and A2Sigma(+) states of the alkali sulfides and the X1Sigma(+), a3Pi, and A1Pi states of the alkaline-earth sulfides. In contrast to the alkali oxides, the alkali sulfides are found to have X2Pi ground states, due to the larger electrostatic interaction. Dissociation energies of 3.27 eV for BeS, 2.32 eV for MgS, 3.29 eV for CaS, and 3.41 eV for SrS have been obtained for the X1Sigma(+) states of the alkaline-earth sulfides, in good agreement with experimental results. Core correlation is shown to increase the Te values for the a3Pi and A1Pi states of MgS, CaS, and SrS.

Optical and electronic properties of conductive ternary nitrides with rare- or alkaline-earth elements

NASA Astrophysics Data System (ADS)

Kassavetis, S.; Hodroj, A.; Metaxa, C.; Logothetidis, S.; Pierson, J. F.; Patsalas, P.

2016-12-01

Conductive nitrides, such as TiN, are key engineering materials for electronics, photonics, and plasmonics; one of the essential issues for such applications is the ability of tuning the conduction electron density, the resistivity, and the electron scattering. While enhancing the conduction electron density and blueshifting the intraband absorption towards the UV were easily achieved previously, reducing the conduction electron density and redshifting the intraband absorption into the infrared are still an open issue. The latter is achieved in this work by alloying TiN by rare earth (RE = Sc, Y, La) or alkaline earth (AE = Mg, Ca) atoms in Ti substitutional positions. The produced TixRE1-xN and TixAE1-xN thin film samples were grown by a hybrid arc evaporation/sputtering process, and most of them are stable in the B1 cubic structure. Their optical properties were studied in an extensive spectral range by spectroscopic ellipsometry. The ellipsometric spectra were analyzed and quantified by the Drude-Lorentz model, which provided the conduction electron density, the electron mean free path, and the resistivity. The observed interband transitions are firmly assigned, and the optical and electrical properties of TixRE1-xN and TixAE1-xN are quantitatively correlated with their composition and crystal structure.

Alkali or alkaline earth metal promoted catalyst and a process for methanol synthesis using alkali or alkaline earth metals as promoters

DOEpatents

Tierney, J.W.; Wender, I.; Palekar, V.M.

1995-01-31

The present invention relates to a novel route for the synthesis of methanol, and more specifically to the production of methanol by contacting synthesis gas under relatively mild conditions in a slurry phase with a heterogeneous catalyst comprising reduced copper chromite impregnated with an alkali or alkaline earth metal. There is thus no need to add a separate alkali or alkaline earth compound. The present invention allows the synthesis of methanol to occur in the temperature range of approximately 100--160 C and the pressure range of 40--65 atm. The process produces methanol with up to 90% syngas conversion per pass and up to 95% methanol selectivity. The only major by-product is a small amount of easily separated methyl formate. Very small amounts of water, carbon dioxide and dimethyl ether are also produced. The present catalyst combination also is capable of tolerating fluctuations in the H[sub 2]/CO ratio without major deleterious effect on the reaction rate. Furthermore, carbon dioxide and water are also tolerated without substantial catalyst deactivation.

Alkali or alkaline earth metal promoted catalyst and a process for methanol synthesis using alkali or alkaline earth metals as promoters

DOEpatents

Tierney, John W.; Wender, Irving; Palekar, Vishwesh M.

1995-01-01

The present invention relates to a novel route for the synthesis of methanol, and more specifically to the production of methanol by contacting synthesis gas under relatively mild conditions in a slurry phase with a heterogeneous catalyst comprising reduced copper chromite impregnated with an alkali or alkaline earth metal. There is thus no need to add a separate alkali or alkaline earth compound. The present invention allows the synthesis of methanol to occur in the temperature range of approximately 100.degree.-160.degree. C. and the pressure range of 40-65 atm. The process produces methanol with up to 90% syngas conversion per pass and up to 95% methanol selectivity. The only major by-product is a small amount of easily separated methyl formate. Very small amounts of water, carbon dioxide and dimethyl ether are also produced. The present catalyst combination also is capable of tolerating fluctuations in the H.sub.2 /CO ratio without major deleterious effect on the reaction rate. Furthermore, carbon dioxide and water are also tolerated without substantial catalyst deactivation.

The alkaline earth intercalates of molybdenum disulfide

NASA Technical Reports Server (NTRS)

Somoano, R. B.; Hadek, V.; Rembaum, A.; Samson, S.; Woollam, J. A.

1975-01-01

Molybdenum disulfide has been intercalated with calcium and strontium by means of the liquid ammonia technique. Chemical, X-ray, and superconductivity data are presented. The X-ray data reveal a lowering of crystal symmetry and increase of complexity of the structure upon intercalation with the alkaline earth metals. The Ca and Sr intercalates start to superconduct at 4 and 5.6 K, respectively, and show considerable anisotropy regarding the critical magnetic field.

Pentadienyl chemistry of the heavy alkaline-earth metals revisited.

PubMed

Reiners, Matthias; Fecker, Ann Christin; Freytag, Matthias; Jones, Peter G; Walter, Marc D

2014-05-14

Open-metallocenes of the heavy alkaline-earth metals [(η(5)-Pdl')2M(thf)n] (M = Ca (1), Sr (2), n = 1; M = Ba (3), n = 2; Pdl' = 2,4-tBu2C5H5) are readily prepared by salt-metathesis between MI2 and KPdl' and characterized by NMR spectroscopy and X-ray diffraction studies.

Theoretical study of the alkaline-earth metal superoxides BeO2 through SrO2

NASA Technical Reports Server (NTRS)

Bauschlicher, Charles W., Jr.; Partridge, Harry; Sodupe, Mariona; Langhoff, Stephen R.

1992-01-01

Three competing bonding mechanisms have been identified for the alkaline-earth metal superoxides: these result in a change in the optimal structure and ground state as the alkaline-earth metal becomes heavier. For example, BeO2 has a linear 3Sigma(-)g ground-state structure, whereas both CaO2 and SrO2 have C(2v)1A1 structures. For MgO2, the theoretical calculations are less definitive, as the 3A2 C(2v) structure is computed to lie only about 3 kcal/mol above the 3Sigma(-)g linear structure. The bond dissociation energies for the alkaline-earth metal superoxides have been computed using extensive Gaussian basis sets and treating electron correlation at the modified coupled-pair functional or coupled-cluster singles and doubles level with a perturbational estimate of the triple excitations.

Alkaline earth metal doped tin oxide as a novel oxygen storage material

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

Dong, Qiang, E-mail: dong@tagen.tohoku.ac.jp; Yin, Shu; Yoshida, Mizuki

2015-09-15

Alkaline earth metal doped tin oxide (SnO{sub 2}) hollow nanospheres with a diameter of 50 nm have been synthesized successfully via a facial solvothermal route in a very simple system composed of only ethanol, acetic acid, SnCl{sub 4}·5H{sub 2}O and A(NO{sub 3}){sub 2}·xH{sub 2}O (A = Mg, Ca, Sr, Ba). The synthesized undoped SnO{sub 2} and A-doped SnO{sub 2} hollow nanospheres were characterized by the oxygen storage capacity (OSC), X-ray diffraction, transmission electron microscopy and the Brunauer–Emmet–Teller (BET) technique. The OSC values of all samples were measured using thermogravimetric-differential thermal analysis. The incorporation of alkaline earth metal ion into tinmore » oxide greatly enhanced the thermal stability and OSC. Especially, Ba-doped SnO{sub 2} hollow nanospheres calcined at 1000 °C for 20 h with a BET surface area of 61 m{sup 2} g{sup −1} exhibited the considerably high OSC of 457 μmol-O g{sup −1} and good thermal stability. Alkaline earth metal doped tin oxide has the potential to be a novel oxygen storage material.« less

Alkaline earth-based coordination polymers derived from a cyclotriphosphazene-functionalized hexacarboxylate

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

Ling, Yajing; Bai, Dongjie; Feng, Yunlong

Combination of hexakis(4-carboxylatephenoxy)cyclotriphosphazene with alkaline earth ions of increasing ionic radii (Mg{sup 2+}, Ca{sup 2+} and Ba{sup 2+}) under different solvothermal conditions yielded three new coordination polymers, and their crystal structures were determined by single-crystal X-ray diffraction analysis. The magnesium compound displays a three dimensional (3D) network structure constructed from the deprotonated ligand and the secondary building block Mg(COO){sub 4}, which can be rationalized as a (4,6)-connected topological net with the Schläfli symbol of (4{sup 4}·6{sup 2}){sub 3}(4{sup 9}·6{sup 6}){sub 2}. The calcium compound consists of 1D infinite “Ca-O” inorganic chains connected by the deprotonated ligands to from a 3Dmore » framework. The barium compound exhibits a 3D framework in which 1D “Ba-O” inorganic chains are connected together by the deprotonated organic linkers. Due to the semi-rigid nature, the ligand adopts distinctly different conformations in the three compounds. The metal ions’ influence exerted on the final structure of the resulting coordination polymers is also discussed. When the radii of alkaline earth ions increases descending down the group from Mg(II) to Ba(II), the coordination number becomes larger and more versatile: from 6 in the magnesium compound, to 6,7 and 10 in the calcium compound, and to 8 and 9 in the barium compound, thus substantially influencing the resulting final framework structures. Also, the photophysical properties were investigated systematically, revealing that the three compounds are photoluminscent in the solid state at room temperature. This work demonstrates that although the multiplicity of conformation in the hexacarboxylate ligand based on the inorganic scaffold cyclotriphosphazene makes it difficult to predict how this ligand will form extended network, but provides unique opportunities for the formation of diverse inorganic-organic hybrids exhibiting rich structural

Rare earth elements: end use and recyclability

USGS Publications Warehouse

Goonan, Thomas G.

2011-01-01

Rare earth elements are used in mature markets (such as catalysts, glassmaking, lighting, and metallurgy), which account for 59 percent of the total worldwide consumption of rare earth elements, and in newer, high-growth markets (such as battery alloys, ceramics, and permanent magnets), which account for 41 percent of the total worldwide consumption of rare earth elements. In mature market segments, lanthanum and cerium constitute about 80 percent of rare earth elements used, and in new market segments, dysprosium, neodymium, and praseodymium account for about 85 percent of rare earth elements used. Regardless of the end use, rare earth elements are not recycled in large quantities, but could be if recycling became mandated or very high prices of rare earth elements made recycling feasible.

Advances in the growth of alkaline-earth halide single crystals for scintillator detectors

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

Boatner, Lynn A; Ramey, Joanne Oxendine; Kolopus, James A

2014-01-01

Alkaline-earth scintillators such as strontium iodide and other alkaline-earth halides activated with divalent europium represent some of the most efficient and highest energy resolution scintillators for use as gamma-ray detectors in a wide range of applications. These applications include the areas of nuclear nonproliferation, homeland security, the detection of undeclared nuclear material, nuclear physics and materials science, medical diagnostics, space physics, high energy physics, and radiation monitoring systems for first responders, police, and fire/rescue personnel. Recent advances in the growth of large single crystals of these scintillator materials hold the promise of higher crystal yields and significantly lower detector productionmore » costs. In the present work, we describe new processing protocols that, when combined with our molten salt filtration methods, have led to advances in achieving a significant reduction of cracking effects during the growth of single crystals of SrI2:Eu2+. In particular, we have found that extended pumping on the molten crystal-growth charge under vacuum for time periods extending up to 48 hours is generally beneficial in compensating for variations in the alkaline-earth halide purity and stoichiometry of the materials as initially supplied by commercial sources. These melt-pumping and processing techniques are now being applied to the purification of CaI2:Eu2+ and some mixed-anion europium-doped alkaline-earth halides prior to single-crystal growth by means of the vertical Bridgman technique. The results of initial studies of the effects of aliovalent doping of SrI2:Eu2+ on the scintillation characteristics of this material are also described.« less

Mineral resource of the month: rare earth elements

USGS Publications Warehouse

,

2011-01-01

The article provides information on rare earth elements, which are group of 17 natural metallic elements. The rare earth elements are scandium, yttrium and lanthanides and classified into light rare earth elements (LREE) and heavy rate earth elements (HREE). The principal ores of the rare earth elements are identified. An overview of China's production of 97 percent of the rare earths in the world is provided. Commercial applications of rare earths are described.

Alkaline earth metallocenes coordinated with ester pendants: synthesis, structural characterization, and application in metathesis reactions.

PubMed

Li, Heng; Zhang, Wen-Xiong; Xi, Zhenfeng

2013-09-16

A variety of ester-substituted cyclopentadiene derivatives have been synthesized by one-pot reactions of 1,4-dilithio-1,3-butadienes, CO, and acid chlorides. Direct deprotonation of the ester-substituted cyclopentadienes with Ae[N(SiMe3 )2 ]2 (Ae=Ca, Sr, Ba) efficiently generated members of a new class of heavier alkaline earth (Ca, Sr, Ba) metallocenes in good to excellent yields. Single-crystal X-ray structural analysis demonstrated that these heavier alkaline earth metallocenes incorporated two intramolecularly coordinated ester pendants and multiply-substituted cyclopentadienyl ligands. The corresponding transition metal metallocenes, such as ferrocene derivatives and half-sandwich cyclopentadienyl tricarbonylrhenium complexes, could be generated highly efficiently by metathesis reactions. The multiply-substituted cyclopentadiene ligands bearing an ester pendant, and the corresponding heavier alkaline earth and transition-metal metallocenes, may have further applications in coordination chemistry, organometallic chemistry, and organic synthesis. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Are concentrations of alkaline earth elements in maternal hair associated with risk of neural tube defects?

PubMed

Li, Zhenjiang; Wang, Bin; Huo, Wenhua; Liu, Yingying; Zhu, Yibing; Xie, Jing; Li, Zhiwen; Ren, Aiguo

2017-12-31

The relationship between maternal intake of alkaline earth elements (AEEs) during the period of neural tube closure and the risk of neural tube defects (NTDs) is still unclear. We propose that AEE deficiency during the early period of pregnancy is associated with an elevated risk of NTDs in the offspring. In this study, we recruited 191 women with NTD-affected pregnancies (cases) and 261 women who delivered healthy infants (controls). The concentrations of four AEEs (Ca, Mg, Sr, Ba) in maternal hair sections that grew during early pregnancy were analyzed. Information on the dietary habits of the mothers was also collected by questionnaire. Higher concentrations of the four AEEs in hair had protective effects against the risk of total NTDs, with odds ratios with 95% confidence interval (comparing groups separated by each median level) of 0.44 (0.28-0.68) for Mg, 0.56 (0.36-0.87) for Ca, 0.45 (0.28-0.70) for Sr, and 0.41 (0.26-0.65) for Ba. Significant negative dose-response trends were identified for the relationships between the four AEE concentrations in maternal hair and the risks of anencephaly and spina bifida, but not for encephalocele. The frequencies of maternal consumption of fresh green vegetables, fresh fruit, and meat or fish were positively correlated with the concentrations of AEEs in hair. We concluded that the maternal intake of AEEs may play an important role in preventing NTD formation in offspring, and that this intake is related to maternal dietary habits of consuming fresh green vegetables, fresh fruit, and fish or meat. Copyright © 2017 Elsevier B.V. All rights reserved.

Rare-earth elements

USGS Publications Warehouse

Van Gosen, Bradley S.; Verplanck, Philip L.; Seal, Robert R.; Long, Keith R.; Gambogi, Joseph; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

2017-12-19

The rare-earth elements (REEs) are 15 elements that range in atomic number from 57 (lanthanum) to 71 (lutetium); they are commonly referred to as the “lanthanides.” Yttrium (atomic number 39) is also commonly regarded as an REE because it shares chemical and physical similarities and has affinities with the lanthanides. Although REEs are not rare in terms of average crustal abundance, the concentrated deposits of REEs are limited in number.Because of their unusual physical and chemical properties, the REEs have diverse defense, energy, industrial, and military technology applications. The glass industry is the leading consumer of REE raw materials, which are used for glass polishing and as additives that provide color and special optical properties to the glass. Lanthanum-based catalysts are used in petroleum refining, and cerium-based catalysts are used in automotive catalytic converters. The use of REEs in magnets is a rapidly increasing application. Neodymium-iron-boron magnets, which are the strongest known type of magnets, are used when space and weight are restrictions. Nickel-metal hydride batteries use anodes made of a lanthanum-based alloys.China, which has led the world production of REEs for decades, accounted for more than 90 percent of global production and supply, on average, during the past decade. Citing a need to retain its limited REE resources to meet domestic requirements as well as concerns about the environmental effects of mining, China began placing restrictions on the supply of REEs in 2010 through the imposition of quotas, licenses, and taxes. As a result, the global rare-earth industry has increased its stockpiling of REEs; explored for deposits outside of China; and promoted new efforts to conserve, recycle, and substitute for REEs. New mine production began at Mount Weld in Western Australia, and numerous other exploration and development projects noted in this chapter are ongoing throughout the world.The REE-bearing minerals are

More arrows in the quiver: new pathways and old problems with heavy alkaline earth metal diphenylmethanides.

PubMed

Alexander, Jacob S; Ruhlandt-Senge, Karin

2004-03-05

Progress in the field of sigma-bonded alkaline earth organometallics has been handicapped by numerous complications, such as high reactivity, low solubility, and the limited availability of suitable starting materials. Here we present two synthetic methods, hydrocarbon elimination and desilylation, as alternative routes into this chemistry. A novel barium diphenylmethanide was prepared using these routes delineating that both methods provide a powerful, versatile synthetic access route to an extended library of organometallic alkaline earth derivatives.

Physical and electrochemical properties of alkaline earth doped, rare earth vanadates

NASA Astrophysics Data System (ADS)

Adijanto, Lawrence; Balaji Padmanabhan, Venu; Holmes, Kevin J.; Gorte, Raymond J.; Vohs, John M.

2012-06-01

The effect of partial substitution of alkaline earth (AE) ions, Sr2+ and Ca2+, for the rare earth (RE) ions, La3+, Ce3+, Pr3+, and Sm3+, on the physical properties of REVO4 compounds were investigated. The use of the Pechini method to synthesize the vanadates allowed for high levels of AE substitution to be obtained. Coulometric titration was used to measure redox isotherms for these materials and showed that the addition of the AE ions increased both reducibility and electronic conductivity under typical solid oxide fuel cell (SOFC) anode conditions, through the formation of compounds with mixed vanadium valence. In spite of their high electronic conductivity, REVO4-yttira stabilized zirconia (YSZ) composite anodes exhibited only modest performance when used in SOFCs operating with H2 fuel at 973 K due to their low catalytic activity. High performance was obtained, however, after the addition of a small amount of catalytically active Pd to the anode.

Coordination Chemistry of Alkali and Alkaline-Earth Cations with Macrocyclic Ligands.

ERIC Educational Resources Information Center

Dietrich, Bernard

1985-01-01

Discusses: (l) alkali and alkaline-earth cations in biology (considering naturally occurring lonophores, their X-ray structures, and physiochemical studies); (2) synthetic complexing agents for groups IA and IIA; and (3) ion transport across membranes (examining neutral macrobicyclic ligands as metal cation carriers, transport by anionic carriers,…

First-principles study on interlayer state in alkali and alkaline earth metal atoms intercalated bilayer graphene

NASA Astrophysics Data System (ADS)

Kaneko, Tomoaki; Saito, Riichiro

2017-11-01

Energetics and electronic structures of alkali metal (Li, Na, K, Rb, and Cs) and alkaline earth metal (Be, Mg, Ca, Sr, and Ba) atoms intercalated bilayer graphene are systematically investigated using first-principles calculations based on density functional theory. Formation of alkali and alkaline earth metal atoms intercalated bilayer graphene is exothermic except for Be and Mg. The interlayer state between two graphene layers is occupied for K, Rb, Cs, Ca, Sr, and Ba. We find that the energetic position of the interlayer states between bilayer graphene monotonically shifts downward with increasing of interlayer distance. The interlayer distances of more than 4.5 Å and 4.0 Å, respectively, are necessary for the occupation of the interlayer state in bilayer graphene for alkali and alkaline earth metal atoms, which is almost independent of the intercalant metal species. We discuss the relevance to occurrence of superconductivity for the metal intercalated bilayer graphene in terms of the occupation of the interlayer state and the phonon frequency of metal ions.

Proposal for Laser Cooling of Alkaline Earth Monoalkoxide Free Radicals

NASA Astrophysics Data System (ADS)

Baum, Louis; Kozyryev, Ivan; Matsuda, Kyle; Doyle, John M.

2016-05-01

Cold samples of polyatomic molecules will open new avenues in physics, chemistry, and quantum science. Non-diagonal Franck-Condon factors, technically challenging wavelengths, and the lack of strong electronic transitions inhibit direct laser cooling of nonlinear molecules. We identify a scheme for optical cycling in certain molecules with six or more atoms. Replacing hydrogen in alcohols with an alkaline earth metal (M) leads to alkaline earth monoalkoxide free radicals (MOR), which have favorable properties for laser cooling. M-O bond is very ionic, so the metal orbitals are slightly affected by the nature of R on the ligand. Diagonal Franck-Condon factors, laser accessible transitions, and a small hyperfine structure make MOR molecules suitable for laser cooling. We explore a scheme for optical cycling on the A - X transition of SrOCH3 . Molecules lost to dark vibrational states will be repumped on the B - X transition. Extension to larger species is possible through expansion of the R group since transitions involve the promotion of the metal-centered nonbonding valence electron. We will detail our estimations of the Franck-Condon factors, simulations of the cooling process and describe progress towards the Doppler cooling of MOR polyatomics.

Alkaline-earth elements of scalp hair and presence of hypertension in housewives: A perspective of chronic effect.

PubMed

Wang, Bin; Yan, Lailai; Sun, Ying; Yan, Jingjing; Lu, Qun; Zhang, Jingxu; Li, Zhiwen

2017-08-01

The relationship between population intakes of alkaline-earth elements (AEEs) and hypertension risk remains under discussion. Hair AEE concentrations can indicate their intake levels into human body. Thus, we aimed to investigate an association of hair AEE concentrations with hypertension risk, and the potential effect of dietary habit on this association. We recruited 398 housewives [163 subjects with hypertension (case group) and 235 subjects without hypertension (control group)] in Shanxi Province of north China. The scalp hair grown in the recent 2 years of each subject was collected and analyzed for the four concerned AEEs [i.e. calcium (Ca), magnesium (Mg), strontium (Sr), and barium (Ba)]. Our study results revealed that median concentrations (μg/g hair) of hair AEEs in the case group were systematically lower than those in control group [i.e. 701 vs. 1271 of Ca, 55.2 vs. 88.3 of Mg, 4.60 vs. 10.4 of Sr, and 1.02 vs. 1.68 of Ba]. Lower levels of the four individual AEEs of hair were associated with an increased presence of hypertension, respectively. Moreover, hair AEE concentrations were all positively correlated with the ingestion frequencies of meat, eggs, fresh vegetables, and fruits, while negatively with that of salted vegetables. A high ingestion frequency of fresh vegetables was associated with a lower prevalence of hypertension with or without adjusting confounders, while salted vegetables revealed a reverse tend. It was concluded that low hair AEEs, as markers of their long-term dietary intake, were associated with the presence of hypertension in a rural Chinese women. Copyright © 2017 Elsevier Ltd. All rights reserved.

Alkali element constraints on Earth-Moon relations

NASA Technical Reports Server (NTRS)

Norman, M. D.; Drake, M. J.; Jones, J. H.

1994-01-01

Given their range of volatilities, alkali elements are potential tracers of temperature-dependent processes during planetary accretion and formation of the Earth-Moon system. Under the giant impact hypothesis, no direct connection between the composition of the Moon and the Earth is required, and proto-lunar material does not necessarily experience high temperatures. Models calling for multiple collisions with smaller planetesimals derive proto-lunar materials mainly from the Earth's mantle and explicitly invoke vaporization, shock melting and volatility-related fractionation. Na/K, K/Rb, and Rb/Cs should all increase in response to thermal volatization, so theories which derive the Moon substantially from Earth's mantle predict these ratios will be higher in the Moon than in the primitive mantle of the Earth. Despite the overall depletion of volatile elements in the Moon, its Na/K and K/Rb are equal to or less than those of Earth. A new model presented here for the composition of Earth's continental crust, a major repository of the alkali elements, suggests the Rb/Cs of the Moon is also less than that of Earth. Fractionation of the alkali elements between Earth and Moon are in the opposite sense to predictions based on the relative volatilities of these elements, if the Moon formed by high-T processing of Earth's mantle. Earth, rather than the Moon, appears to carry a signature of volatility-related fractionation in the alkali elements. This may reflect an early episode of intense heating on Earth with the Moon's alkali budget accreting from cooler material.

Preconcentration and determination of rare-earth elements in iron-rich water samples by extraction chromatography and plasma source mass spectrometry (ICP-MS).

PubMed

Hernández González, Carolina; Cabezas, Alberto J Quejido; Díaz, Marta Fernández

2005-11-15

A 100-fold preconcentration procedure based on rare-earth elements (REEs) separation from water samples with an extraction chromatographic column has been developed. The separation of REEs from matrix elements (mainly Fe, alkaline and alkaline-earth elements) in water samples was performed loading the samples, previously acidified to pH 2.0 with HNO(3), in a 2ml column preconditioned with 20ml 0.01M HNO(3). Subsequently, REEs were quantitatively eluted with 20ml 7M HNO(3). This solution was evaporated to dryness and the final residue was dissolved in 10ml 2% HNO(3) containing 1mugl(-1) of cesium used as internal standard. The solution was directly analysed by inductively coupled plasma mass spectrometry (ICP-MS), using ultrasonic nebulization, obtaining quantification limits ranging from 0.05 to 0.10 ngl(-1). The proposed method has been applied to granitic waters running through fracture fillings coated by iron and manganese oxy-hydroxides in the area of the Ratones (Cáceres, Spain) old uranium mine.

Rare earth elements upon assessment of reasons of the geophagy in Sikhote-Alin region (Russian Federation), Africa and other world regions.

PubMed

Panichev, Alexander M; Popov, Vladimir K; Chekryzhov, Igor Yu; Seryodkin, Ivan V; Stolyarova, Tatiana A; Zakusin, Sergey V; Sergievich, Alexandr A; Khoroshikh, Pavel P

2016-12-01

Rocks eaten by wild animals on the Bolshoy Shanduyskiy kudur in the Sikhote-Alin region (Russian Federation) are zeolite-clay mineral complexes-products of weathering of zeolitized vitric tuffs of rhyolite composition, deposited in aqueous medium within the volcanic caldera of about 55 million years ago. By composition of rock-forming oxides, the tuffs refer to high-potassium calc-alkaline series. In trace elements of most favorite kudurites of the Bolshoy Shanduyskiy kudur, there are significantly increased contents of most of rare earth elements (2-5 times in comparison with surrounding rocks). The results of our analysis of geological and geochemical data on kudurs and kudurites in another part of the Sikhote-Alin, as well as on other regions of the world (particularly, in Africa and Indonesia), taking into account new data on the prevalence of rare earth elements in living matter and their medical and biological properties, enable us to consider the version of causal connection of the geophagy with rare earth elements.

Oxidation behavior of Cr(III) during thermal treatment of chromium hydroxide in the presence of alkali and alkaline earth metal chlorides.

PubMed

Mao, Linqiang; Gao, Bingying; Deng, Ning; Liu, Lu; Cui, Hao

2016-02-01

The oxidation behavior of Cr(III) during the thermal treatment of chromium hydroxide in the presence of alkali and alkaline earth metal chlorides (NaCl, KCl, MgCl2, and CaCl2) was investigated. The amounts of Cr(III) oxidized at various temperatures and heating times were determined, and the Cr-containing species in the residues were characterized. During the transformation of chromium hydroxide to Cr2O3 at 300 °C approximately 5% of the Cr(III) was oxidized to form intermediate compounds containing Cr(VI) (i.e., CrO3), but these intermediates were reduced to Cr2O3 when the temperature was above 400 °C. Alkali and alkaline earth metals significantly promoted the oxidation of Cr(III) during the thermal drying process. Two pathways were involved in the influences the alkali and alkaline earth metals had on the formation of Cr(VI). In pathway I, the alkali and alkaline earth metals were found to act as electron transfer agents and to interfere with the dehydration process, causing more intermediate Cr(VI)-containing compounds (which were identified as being CrO3 and Cr5O12) to be formed. The reduction of intermediate compounds to Cr2O3 was also found to be hindered in pathway I. In pathway II, the alkali and alkaline earth metals were found to contribute to the oxidation of Cr(III) to form chromates. The results showed that the presence of alkali and alkaline earth metals significantly increases the degree to which Cr(III) is oxidized during the thermal drying of chromium-containing sludge. Copyright © 2015 Elsevier Ltd. All rights reserved.

Origin of low sodium capacity in graphite and generally weak substrate binding of Na and Mg among alkali and alkaline earth metals.

PubMed

Liu, Yuanyue; Merinov, Boris V; Goddard, William A

2016-04-05

It is well known that graphite has a low capacity for Na but a high capacity for other alkali metals. The growing interest in alternative cation batteries beyond Li makes it particularly important to elucidate the origin of this behavior, which is not well understood. In examining this question, we find a quite general phenomenon: among the alkali and alkaline earth metals, Na and Mg generally have the weakest chemical binding to a given substrate, compared with the other elements in the same column of the periodic table. We demonstrate this with quantum mechanics calculations for a wide range of substrate materials (not limited to C) covering a variety of structures and chemical compositions. The phenomenon arises from the competition between trends in the ionization energy and the ion-substrate coupling, down the columns of the periodic table. Consequently, the cathodic voltage for Na and Mg is expected to be lower than those for other metals in the same column. This generality provides a basis for analyzing the binding of alkali and alkaline earth metal atoms over a broad range of systems.

Rare Earth Elements | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

- Mineral Resources main content Rare Earth Elements Rare earth elements and the supply and demand of these deposits containing rare earth elements to meet the perceived future demand. High prices for rare earth earth element occurrences in the DGGS publications catalog. Department of Natural Resources, Division of

Enhanced NO2 abatement by alkaline-earth modified g-C3N4 nanocomposites for efficient air purification

NASA Astrophysics Data System (ADS)

Papailias, Ilias; Todorova, Nadia; Giannakopoulou, Tatiana; Karapati, Sofia; Boukos, Nikos; Dimotikali, Dimitra; Trapalis, Christos

2018-02-01

The emission of nitrogen dioxide (NO2) is a major problem encountered in photocatalytic NOx removal for air purification. Although the oxidation of nitric oxide (NO) has been extensively studied, the elimination of NO2 byproduct is still in preliminary stage. In this work, alkaline-earth modified graphitic carbon nitride (g-C3N4) is proposed for efficient NOx removal by minimizing the emission of NO2 during the NO oxidation process. The novel photocatalysts were synthesized by annealing mixtures of melamine and various alkaline-earth acetates (magnesium, calcium and barium acetate) at 550 °C for 3 h. The specific surface area of the photocatalysts varied between 4.65 and 11.81 m2/g. The formation of MgO, CaCO3 and BaCO3 was demonstrated by XPS and FT-IR analyses. The initial concentration of each alkaline-earth precursor was 5 and 10 wt%, while the final metal concentration in the nanocomposites was in the range of 7.19-22.39 wt%. The modified photocatalysts showed slightly reduced NO oxidation ability. However, the overall air quality was significantly improved by restraining the NO2 emission. The results were related to the basic character of the nanocomposites due to the presence of alkaline-earths and their enhanced NO2 adsorption capability.

Ab initio calculations on the positive ions of the alkaline-earth oxides, fluorides, and hydroxides

NASA Technical Reports Server (NTRS)

Partridge, H.; Langhoff, S. R.; Bauschlicher, C. W., Jr.

1986-01-01

Theoretical dissociation energies are presented for the alkaline-earth fluoride, hydroxide, and oxide positive ions that are considered to be accurate to 0.1-0.2 eV. The r(e) for the positive ions are found to be consistently shorter than the corresponding neutrals by 0.07 + or -0.02 A. The bonding in the ground states is demonstrated to be of predominantly M + 2 X - character. The a 3 Pi and A 1 Pi are found to lie considerably above the X 1 Sigma + ground states of the alkaline-earth fluoride and hydroxide positive ions. The overall agreement of the theoretical ionization potentials with the available experimental appearance potentials is satisfactory; these values should represent the most accurate and consistent set available.

Effect of alkaline earth modifier on the optical and structural properties of Cu2+ doped phosphate glasses as a bandpass filter

NASA Astrophysics Data System (ADS)

Farouk, M.; Samir, A.; El Okr, M.

2018-02-01

Glasses of composition [16RO-3Al2O3sbnd 6CuOsbnd 20Na2Osbnd 55P2O5], where R is the alkaline earth (R = Mg, Ca, Sr and Ba mol. %), were prepared by conventional melt quenching technique. The glass samples were characterized by X-ray diffraction, infrared spectroscopy, and spectrophotometer. XRD patterns show no sharp peaks indicating the non-crystalline nature of the prepared glasses. The density and molar volume of the glass systems were determined in order to study their structures. These results revealed that addition of alkaline earth elements leads to the formation of non-bridging oxygens (NBOs) and expands (opens up) the structure. The infrared spectra were analyzed to quantify the present phosphate groups. The optical absorption spectra of Cu2+ ions show the characteristic broadband single of Cu2+ ions in octahedral symmetry. The band gap was estimated following two methodologies. The first method considers the band edge of the transmission, while the second approach relays on the estimated values of the optical constants. A decent agreement for the band gap values using the two methods was obtained.

Alkaline quinone flow battery.

PubMed

Lin, Kaixiang; Chen, Qing; Gerhardt, Michael R; Tong, Liuchuan; Kim, Sang Bok; Eisenach, Louise; Valle, Alvaro W; Hardee, David; Gordon, Roy G; Aziz, Michael J; Marshak, Michael P

2015-09-25

Storage of photovoltaic and wind electricity in batteries could solve the mismatch problem between the intermittent supply of these renewable resources and variable demand. Flow batteries permit more economical long-duration discharge than solid-electrode batteries by using liquid electrolytes stored outside of the battery. We report an alkaline flow battery based on redox-active organic molecules that are composed entirely of Earth-abundant elements and are nontoxic, nonflammable, and safe for use in residential and commercial environments. The battery operates efficiently with high power density near room temperature. These results demonstrate the stability and performance of redox-active organic molecules in alkaline flow batteries, potentially enabling cost-effective stationary storage of renewable energy. Copyright © 2015, American Association for the Advancement of Science.

Sign Changes in the Electric Dipole Moment of Excited States in Rubidium-Alkaline Earth Diatomic Molecules

NASA Astrophysics Data System (ADS)

Pototschnig, Johann V.; Lackner, Florian; Hauser, Andreas W.; Ernst, Wolfgang E.

2015-06-01

In a recent series of combined experimental and theoretical studies we investigated the ground state and several excited states of the Rb-alkaline earth molecules RbSr and RbCa. The group of alkali-alkaline earth (AK-AKE) molecules has drawn attention for applications in ultracold molecular physics and the measurement of fundamental constants due to their large permanent electric and magnetic dipole moments in the ground state. These properties should allow for an easy manipulation of the molecules and simulations of spin models in optical lattices. In our studies we found that the permanent electric dipole moment points in different directions for certain electronically excited states, and changes the sign in some cases as a function of bond length. We summarize our results, give possible causes for the measured trends in terms of molecular orbital theory and extrapolate the tendencies to other combinations of AK and AKE - elements. F. Lackner, G. Krois, T. Buchsteiner, J. V. Pototschnig, and W. E. Ernst, Phys. Rev. Lett., 2014, 113, 153001; G. Krois, F. Lackner, J. V. Pototschnig, T. Buchsteiner, and W. E. Ernst, Phys. Chem. Chem. Phys., 2014, 16, 22373; J. V. Pototschnig, G. Krois, F. Lackner, and W. E. Ernst, J. Chem. Phys., 2014, 141, 234309 J. V. Pototschnig, G. Krois, F. Lackner, and W. E. Ernst, J. Mol. Spectrosc., in Press (2015), doi:10.1016/j.jms.2015.01.006 M. Kajita, G. Gopakumar, M. Abe, and M. Hada, J. Mol. Spectrosc., 2014, 300, 99-107 A. Micheli, G. K. Brennen, and P. Zoller, Nature Physics, 2006, 2, 341-347

Promoting effect of alkaline earth metal doping on catalytic activity of HC and NOx conversion over Pd-only three-way catalyst.

PubMed

Yang, Linyan; Lin, Siyu; Yang, Xue; Fang, Weimin; Zhou, Renxian

2014-08-30

The influence of alkaline earth metal (M=Mg, Ca, Sr and Ba) promoter on the structural/textural properties of Ce0.67Zr0.33O2 (designated as CZ) and the catalytic behavior of its supported Pd-only three-way catalyst (Pd/CZM) have been investigated. The results show that the modification with alkaline earth metal obviously improves the catalytic activity for hydrocarbon (HC) and nitrogen oxides (NOx) conversion, especially the introduction of Ba. Furthermore, the operation window of the promoted catalysts has also been widened. The doping of alkaline earth metal leads to the formation of more homogeneous Ce-Zr-M ternary solid solution with higher surface area and smaller crystallite size, and the corresponding Pd/CZM catalysts present improved reducibility of PdO species. The modification with Ca, Sr and Ba improves the thermal aging resistance, especially Ba. DRIFTS results reveal that the doping of alkaline earth metal enhances the oxygen and electron transfer ability and favors the dissociation of NO, which promotes the activation and storage capacity of the acidic atoms like NOx, and leads to enhanced catalytic activity performance. Copyright © 2014 Elsevier B.V. All rights reserved.

Structure and ionic diffusion of alkaline-earth ions in mixed cation glasses A 2O–2MO–4SiO 2 with molecular dynamics simulations

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

Konstantinou, Konstantinos; Sushko, Petr; Duffy, Dorothy M.

2015-05-15

A series of mixed cation silicate glasses of the composition A2O – 2MO – 4SiO2, with A=Li,Na,K and M=Ca,Sr,Ba has been investigated by means of molecular dynamics simulations in order to understand the effect of the nature of the cations on the mobility of the alkaline-earth ions within the glass network. The size of the alkaline-earth cation was found to affect the inter-atomic distances, the coordination number distributions and the bond angle distributions , whereas the medium-range order was almost unaffected by the type of the cation. All the alkaline-earth cations contribute to lower vibrational frequencies but it is observedmore » that that there is a shift to smaller frequencies and the vibrational density of states distribution gets narrower as the size of the alkaline-earth increases. The results from our modeling for the ionic diffusion of the alkaline-earth cations are in a qualitative agreement with the experimental observations in that there is a distinct correlation between the activation energy for diffusion of alkaline earth-ions and the cation radii ratio. An asymmetrical linear behavior in the diffusion activation energy with increasing size difference is observed. The results can be described on the basis of a theoretical model that relates the diffusion activation energy to the electrostatic interactions of the cations with the oxygens and the elastic deformation of the silicate network.« less

IUPAC-NIST Solubility Data Series. 95. Alkaline Earth Carbonates in Aqueous Systems. Part 2. Ca

NASA Astrophysics Data System (ADS)

Vanderdeelen, Jan

2012-06-01

The alkaline earth carbonates are an important class of minerals. This article is part of a volume in the IUPAC-NIST Solubility Data Series that compiles and critically evaluates solubility data of the alkaline earth carbonates in water and in simple aqueous electrolyte solutions. Part 1 outlined the procedure adopted in this volume, and presented the beryllium and magnesium carbonates. Part 2, the current paper, compiles and critically evaluates the solubility data of calcium carbonate. The chemical forms included are the anhydrous CaCO3 types calcite, aragonite, and vaterite, the monohydrate monohydrocalcite (CaCO3. H2O), the hexahydrate ikaite (CaCO3.6H2O), and an amorphous form. The data were analyzed with two model variants, and thermodynamic data of each form consistent with each of the models and with the CODATA key values for thermodynamics are presented.

Accumulation of alkaline earth metals by the green macroalga Bryopsis maxima.

PubMed

Takahashi, Shigekazu; Aizawa, Kyoko; Nakamura, Saki; Nakayama, Katsumi; Fujisaki, Shingo; Watanabe, Soichiro; Satoh, Hiroyuki

2015-04-01

Twenty-five days after the disaster at the Fukushima Daiichi nuclear power plant in 2011, we collected samples of the green macroalga Bryopsis maxima from the Pacific coast of Japan. Bryopsis maxima is a unicellular, multinuclear, siphonous green macroalga. Radiation analysis revealed that B. maxima emitted remarkably high gamma radiation of (131)I, (134)Cs, (137)Cs, and (140)Ba as fission products of (235)U. Interestingly, B. maxima contained naturally occurring radionuclides derived from (226)Ra and (228)Ra. Analysis of element content revealed that B. maxima accumulates many ocean elements, especially high quantities of the alkaline earth metals Sr (15.9 g per dry-kg) and Ba (3.79 g per dry-kg), whereas Ca content (12.5 g per dry-kg) was lower than that of Sr and only 61 % of the mean content of 70 Japanese seaweed species. Time-course analysis determined the rate of radioactive (85)Sr incorporation into thalli to be approximately 0.13 g Sr per dry-kg of thallus per day. Subcellular fractionation of B. maxima cells showed that most of the (85)Sr was localized in the soluble fraction, predominantly in the vacuole or cytosol. Given that (85)Sr radioactivity was permeable through a dialysis membrane, the (85)Sr was considered to be a form of inorganic ion and/or bound with a small molecule. Precipitation analysis with sodium sulfate showed that more than 70% of the Sr did not precipitate as SrSO4, indicating that a proportion of the Sr may bind with small molecules in B. maxima.

Rare Earth Element Mines, Deposits, and Occurrences

USGS Publications Warehouse

Orris, Greta J.; Grauch, Richard I.

2002-01-01

Data on rare earth (including yttrium) mines, deposits, and occurrences were compiled as part of an effort by the USGS and the University of Arizona Center for Mineral Resources to summarize current knowledge on the supply and demand outlook and related topics for this group of elements. Economic competition and environmental concerns are increasingly constraining the mining and processing of rare earths from the Mountain Pass mine in California. For many years, the deposit at Mountain Pass was the world's dominant source of rare earth elements and the United States was essentially self-sufficient. Starting approximately 10 years ago, the U.S. has become increasingly dependent (> 90 percent of separated rare earths) upon imports from China, now the dominant source of rare earths. A knowledge of the known economic and noneconomic sources of rare earths is basic to evaluating the outlook for rare earth supply and associated issues.

Core-Mantle Partitioning of Volatile Elements and the Origin of Volatile Elements in Earth and Moon

NASA Technical Reports Server (NTRS)

Righter, K.; Pando, K.; Danielson, L.; Nickodem, K.

2014-01-01

Depletions of siderophile elements in mantles have placed constraints on the conditions on core segregation and differentiation in bodies such as Earth, Earth's Moon, Mars, and asteroid 4 Vesta. Among the siderophile elements there are a sub-set that are also volatile (volatile siderophile elements or VSE; Ga, Ge, In, As, Sb, Sn, Bi, Zn, Cu, Cd), and thus can help to constrain the origin of volatile elements in these bodies, and in particular the Earth and Moon. One of the fundamental observations of the geochemistry of the Moon is the overall depletion of volatile elements relative to the Earth, but a satisfactory explanation has remained elusive. Hypotheses for Earth include addition during accretion and core formation and mobilized into the metallic core, multiple stage origin, or addition after the core formed. Any explanation for volatile elements in the Earth's mantle must also be linked to an explanation of these elements in the lunar mantle. New metal-silicate partitioning data will be applied to the origin of volatile elements in both the Earth and Moon, and will evaluate theories for exogenous versus endogenous origin of volatile elements.

Structural diversity of alkaline-earth 2,5-thiophenedicarboxylates

NASA Astrophysics Data System (ADS)

Balendra; Ramanan, Arunachalam

2017-03-01

Exploration of the structural landscape of the system containing divalent alkaline-earth metal ion (Mg, Ca and Sr) with the rigid 2,5-thiophenedicarboxylic acid (TDC) under varying solvothermal condition (DMF, DMA and DEF) yielded five new crystals: [Mg(TDC) (DEF)2(H2O)1/2] (1), [Ca(TDC) (DMA)] (2), [Ca(TDC) (DMA) (H2O)] (3), [Sr(TDC) (DMA)] (4) and [Sr(TDC) (DMA) (H2O)] (5) and two known solids. Single crystal structures of all the solids are characteristic of extended coordination interaction between metal and carboxylate ions. While the smaller magnesium ion crystallized into a 2D coordination polymer, the larger calcium and strontium compounds resulted into the growth of 3D metal organic frameworks. All the solids show blue emission arising from intra ligand charge transfer.

Kinetics of the mechanochemical synthesis of alkaline-earth metal amides

NASA Astrophysics Data System (ADS)

Garroni, Sebastiano; Takacs, Laszlo; Leng, Haiyan; Delogu, Francesco

2014-07-01

A phenomenological framework is developed to model the kinetics of the formation of alkaline-earth metal amides by the ball milling induced reaction of their hydrides with gaseous ammonia. It is shown that the exponential character of the kinetic curves is modulated by the increase of the total volume of the powder inside the reactor due to the substantially larger molar volume of the products compared to the reactants. It is claimed that the volume of powder effectively processed during each collision connects the transformation rate to the physical and chemical processes underlying the mechanochemical transformations.

Google Earth locations of USA and seafloor hydrothermal vents with associated rare earth element data

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

Andrew Fowler

Google Earth .kmz files that contain the locations of geothermal wells and thermal springs in the USA, and seafloor hydrothermal vents that have associated rare earth element data. The file does not contain the actual data, the actual data is available through the GDR website in two tier 3 data sets entitled "Compilation of Rare Earth Element Analyses from US Geothermal Fields and Mid Ocean Ridge (MOR) Hydrothermal Vents" and "Rare earth element content of thermal fluids from Surprise Valley, California"

Determination of thorium and of rare earth elements in cerium earth minerals and ores

USGS Publications Warehouse

Carron, M.K.; Skinner, D.L.; Stevens, R.E.

1955-01-01

The conventional oxalate method for precipitating thorium and the rare earth elements in acid solution exhibits definite solubilities of these elements. The present work was undertaken to establish conditions overcoming these solubilities and to find optimum conditions for precipitating thorium and the rare earth elements as hydroxides and sebacates. The investigations resulted in a reliable procedure applicable to samples in which the cerium group elements predominate. The oxalate precipitations are made from homogeneous solution at pH 2 by adding a prepared solution of anhydrous oxalic acid in methanol instead of the more expensive crystalline methyl oxalate. Calcium is added as a carrier. Quantitative precipitation of thorium and the rare earth elements is ascertained by further small additions of calcium to the supernatant liquid, until the added calcium precipitates as oxalate within 2 minutes. Calcium is removed by precipitating the hydroxides of thorium and rare earths at room temperature by adding ammonium hydroxide to pH > 10. Thorium is separated as the sebacate at pH 2.5, and the rare earths are precipitated with ammonium sebacate at pH 9. Maximum errors for combined weights of thorium and rare earth oxides on synthetic mixtures are ??0.6 mg. Maximum error for separated thoria is ??0.5 mg.

IUPAC-NIST Solubility Data Series. 95. Alkaline Earth Carbonates in Aqueous Systems. Part 2. Ca

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

De Visscher, Alex; Vanderdeelen, Jan; Department of Applied Analytical and Physical Chemistry, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent

The alkaline earth carbonates are an important class of minerals. This article is part of a volume in the IUPAC-NIST Solubility Data Series that compiles and critically evaluates solubility data of the alkaline earth carbonates in water and in simple aqueous electrolyte solutions. Part 1 outlined the procedure adopted in this volume, and presented the beryllium and magnesium carbonates. Part 2, the current paper, compiles and critically evaluates the solubility data of calcium carbonate. The chemical forms included are the anhydrous CaCO{sub 3} types calcite, aragonite, and vaterite, the monohydrate monohydrocalcite (CaCO{sub 3}{center_dot} H{sub 2}O), the hexahydrate ikaite (CaCO{sub 3}{center_dot}6H{submore » 2}O), and an amorphous form. The data were analyzed with two model variants, and thermodynamic data of each form consistent with each of the models and with the CODATA key values for thermodynamics are presented.« less

Diffusive exchange of trace elements between alkaline melts: Implications for element fractionation and timescale estimations during magma mixing

NASA Astrophysics Data System (ADS)

González-Garcia, Diego; Petrelli, Maurizio; Behrens, Harald; Vetere, Francesco; Fischer, Lennart A.; Morgavi, Daniele; Perugini, Diego

2018-07-01

The diffusive exchange of 30 trace elements (Cs, Rb, Ba, Sr, Co, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ta, V, Cr, Pb, Th, U, Zr, Hf, Sn and Nb) during the interaction of natural mafic and silicic alkaline melts was experimentally studied at conditions relevant to shallow magmatic systems. In detail, a set of 12 diffusion couple experiments have been performed between natural shoshonitic and rhyolitic melts from the Vulcano Island (Aeolian archipelago, Italy) at a temperature of 1200 °C, pressures from 50 to 500 MPa, and water contents ranging from nominally dry to ca. 2 wt.%. Concentration-distance profiles, measured by Laser Ablation ICP-MS, highlight different behaviours, and trace elements were divided into two groups: (1) elements with normal diffusion profiles (13 elements, mainly low field strength and transition elements), and (2) elements showing uphill diffusion (17 elements including Y, Zr, Nb, Pb and rare earth elements, except Eu). For the elements showing normal diffusion profiles, chemical diffusion coefficients were estimated using a concentration-dependent evaluation method, and values are given at four intermediate compositions (SiO2 equal to 58, 62, 66 and 70 wt.%, respectively). A general coupling of diffusion coefficients to silica diffusivity is observed, and variations in systematics are observed between mafic and silicic compositions. Results show that water plays a decisive role on diffusive rates in the studied conditions, producing an enhancement between 0.4 and 0.7 log units per 1 wt.% of added H2O. Particularly notable is the behaviour of the trivalent-only REEs (La to Nd and Gd to Lu), with strong uphill diffusion minima, diminishing from light to heavy REEs. Modelling of REE profiles by a modified effective binary diffusion model indicates that activity gradients induced by the SiO2 concentration contrast are responsible for their development, inducing a transient partitioning of REEs towards the shoshonitic melt

MaRGEE: Move and Rotate Google Earth Elements

NASA Astrophysics Data System (ADS)

Dordevic, Mladen M.; Whitmeyer, Steven J.

2015-12-01

Google Earth is recognized as a highly effective visualization tool for geospatial information. However, there remain serious limitations that have hindered its acceptance as a tool for research and education in the geosciences. One significant limitation is the inability to translate or rotate geometrical elements on the Google Earth virtual globe. Here we present a new JavaScript web application to "Move and Rotate Google Earth Elements" (MaRGEE). MaRGEE includes tools to simplify, translate, and rotate elements, add intermediate steps to a transposition, and batch process multiple transpositions. The transposition algorithm uses spherical geometry calculations, such as the haversine formula, to accurately reposition groups of points, paths, and polygons on the Google Earth globe without distortion. Due to the imminent deprecation of the Google Earth API and browser plugin, MaRGEE uses a Google Maps interface to facilitate and illustrate the transpositions. However, the inherent spatial distortions that result from the Google Maps Web Mercator projection are not apparent once the transposed elements are saved as a KML file and opened in Google Earth. Potential applications of the MaRGEE toolkit include tectonic reconstructions, the movements of glaciers or thrust sheets, and time-based animations of other large- and small-scale geologic processes.

Biogenesis and early life on Earth and Europa: favored by an alkaline ocean?

PubMed

Kempe, Stephan; Kazmierczak, Jozef

2002-01-01

Recent discoveries about Europa--the probable existence of a sizeable ocean below its ice crust; the detection of hydrated sodium carbonates, among other salts; and the calculation of a net loss of sodium from the subsurface--suggest the existence of an alkaline ocean. Alkaline oceans (nicknamed "soda oceans" in analogy to terrestrial soda lakes) have been hypothesized also for early Earth and Mars on the basis of mass balance considerations involving total amounts of acids available for weathering and the composition of the early crust. Such an environment could be favorable to biogenesis since it may have provided for very low Ca2+ concentrations mandatory for the biochemical function of proteins. A rapid loss of CO2 from Europa's atmosphere may have led to freezing oceans. Alkaline brine bubbles embedded in ice in freezing and impact-thawing oceans could have provided a suitable environment for protocell formation and the large number of trials needed for biogenesis. Understanding these processes could be central to assessing the probability of life on Europa.

NETL’s Rare Earth Elements Research

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

None

The National Energy Technology Laboratory has established a Rare Earth Elements (REE) program. REEs are a series of 17 chemical elements found in the Earth’s crust. They are an essential component to technology, health care, transportation and national defense.

Dynamical Correlation In Some Liquid Alkaline Earth Metals Near Melting

NASA Astrophysics Data System (ADS)

Thakore, B. Y.; Suthar, P. H.; Khambholja, S. G.; Gajjar, P. N.; Jani, A. R.

2010-12-01

The study of dynamical variables: velocity autocorrelation function (VACF) and power spectrum of liquid alkaline earth metals (Ca, Sr, and Ba) have been presented based on the static harmonic well approximation. The effective interatomic potential for liquid metals is computed using our well recognized model potential with the exchange correlation functions due to Hartree, Taylor, Ichimaru and Utsumi, Farid et al. and Sarkar et al. It is observed that the VACF computed using Sarkar et al. gives the good agreement with available molecular dynamics simulation (MD) results [Phys Rev. B 62, 14818 (2000)]. The shoulder of the power spectrum depends upon the type of local field correlation function used.

Assessment of band gaps for alkaline-earth chalcogenides using improved Tran Blaha-modified Becke Johnson potential

NASA Astrophysics Data System (ADS)

Yedukondalu, N.; Kunduru, Lavanya; Roshan, S. C. Rakesh; Sainath, M.

2018-04-01

Assessment of band gaps for nine alkaline-earth chalcogenides namely MX (M = Ca, Sr, Ba and X = S, Se Te) compounds are reported using Tran Blaha-modified Becke Johnson (TB-mBJ) potential and its new parameterization. From the computed electronic band structures at the equilibrium lattice constants, these materials are found to be indirect band gap semiconductors at ambient conditions. The calculated band gaps are improved using TB-mBJ and its new parameterization when compared to local density approximation (LDA) and Becke Johnson potentials. We also observe that TB-mBJ new parameterization for semiconductors below 7 eV reproduces the experimental trends very well for the small band gap semiconducting alkaline-earth chalcogenides. The calculated band profiles look similar for MX compounds (electronic band structures are provided for BaS for representation purpose) using LDA and new parameterization of TB-mBJ potentials.

Solvation structures and dynamics of alkaline earth metal halides in supercritical water: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Keshri, Sonanki; Mandal, Ratnamala; Tembe, B. L.

2016-09-01

Constrained molecular dynamics simulations of alkaline earth metal halides have been carried out to investigate their structural and dynamical properties in supercritical water. Potentials of mean force (PMFs) for all the alkaline earth metal halides in supercritical water have been computed. Contact ion pairs (CIPs) are found to be more stable than all other configurations of the ion pairs except for MgI2 where solvent shared ion pair (SShIP) is more stable than the CIP. There is hardly any difference in the PMFs between the M2+ (M = Mg, Ca, Sr, Ba) and the X- (X = F, Cl, Br, I) ions whether the second X- ion is present in the first coordination shell of the M2+ ion or not. The solvent molecules in the solvation shells diffuse at a much slower rate compared to the bulk. Orientational distribution functions of solvent molecules are sharper for smaller ions.

SEPARATION OF TRANSURANIC ELEMENTS FROM RARE EARTH COMPOUNDS

DOEpatents

Kohman, T.P.

1961-11-21

A process of separating neptunium and plutonium values from rare earths and alkaline earth fission products present on a solid mixed actinide carrier (Th or U(IV) oxalate or fluoride) --fission product carrier (LaF/sub 3/, CeF/sub 3/, SrF/sub 2/, CaF/sub 2/, YF/sub 3/, La oxalate, cerous oxalate, Sr oxalate, Ca oxalate or Y oxalate) by extraction of the actinides at elevated temperature with a solution of ammonium fluoride and/or ammonium oxalate is described. Separation of the fission-product-containing carriers from the actinide solution formed and precipitation of the neptunium and plutonium from the solution with mineral acid are also accomplished. (AEC)

Rare Earth Element Concentration of Wyoming Thermal Waters Update

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

Quillinan, Scott; Nye, Charles; Neupane, Hari

Updated version of data generated from rare earth element investigation of produced waters. These data represent major, minor, trace, isotopes, and rare earth element concentrations in geologic formations and water associated with oil and gas production.

NMR parameters in alkali, alkaline earth and rare earth fluorides from first principle calculations.

PubMed

Sadoc, Aymeric; Body, Monique; Legein, Christophe; Biswal, Mamata; Fayon, Franck; Rocquefelte, Xavier; Boucher, Florent

2011-11-07

(19)F isotropic chemical shifts for alkali, alkaline earth and rare earth of column 3 basic fluorides are measured and the corresponding isotropic chemical shieldings are calculated using the GIPAW method. When using the PBE exchange-correlation functional for the treatment of the cationic localized empty orbitals of Ca(2+), Sc(3+) (3d) and La(3+) (4f), a correction is needed to accurately calculate (19)F chemical shieldings. We show that the correlation between experimental isotropic chemical shifts and calculated isotropic chemical shieldings established for the studied compounds allows us to predict (19)F NMR spectra of crystalline compounds with a relatively good accuracy. In addition, we experimentally determine the quadrupolar parameters of (25)Mg in MgF(2) and calculate the electric field gradients of (25)Mg in MgF(2) and (139)La in LaF(3) using both PAW and LAPW methods. The orientation of the EFG components in the crystallographic frame, provided by DFT calculations, is analysed in terms of electron densities. It is shown that consideration of the quadrupolar charge deformation is essential for the analysis of slightly distorted environments or highly irregular polyhedra. This journal is © the Owner Societies 2011

Rare earth element scavenging in seawater

NASA Astrophysics Data System (ADS)

Byrne, Robert H.; Kim, Ki-Hyun

1990-10-01

Examinations of rare earth element (REE) adsorption in seawater, using a variety of surface-types, indicated that, for most surfaces, light rare earth elements (LREEs) are preferentially adsorbed compared to the heavy rare earths (HREEs). Exceptions to this behavior were observed only for silica phases (glass surfaces, acid-cleaned diatomaceous earth, and synthetic SiO 2). The affinity of the rare earths for surfaces can be strongly affected by thin organic coatings. Glass surfaces which acquired an organic coating through immersion in Tampa Bay exhibited adsorptive behavior typical of organic-rich, rather than glass, surfaces. Models of rare earth distributions between seawater and carboxylate-rich surfaces indicate that scavenging processes which involve such surfaces should exhibit a strong dependence on pH and carbonate complexation. Scavenging models involving carboxylate surfaces produce relative REE abundance patterns in good general agreement with observed shale-normalized REE abundances in seawater. Scavenging by carboxylate-rich surfaces should produce HREE enrichments in seawater relative to the LREEs and may produce enrichments of lanthanum relative to its immediate trivalent neighbors. Due to the origin of distribution coefficients as a difference between REE solution complexation (which increases strongly with atomic number) and surface complexation (which apparently also increases with atomic number) the relative solution abundance patterns of the REEs produced by scavenging reactions can be quite complex.

Optimizing the performance of bandpass photon detectors for inverse photoemission: Transmission of alkaline earth fluoride window crystals

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

Thiede, Christian, E-mail: christian.thiede@uni-muenster.de; Schmidt, Anke B.; Donath, Markus

2015-08-15

Bandpass photon detectors are widely used in inverse photoemission in the isochromat mode at energies in the vacuum-ultraviolet spectral range. The energy bandpass of gas-filled counters is usually formed by the ionization threshold of the counting gas as high-pass filter and the transmission cutoff of an alkaline earth fluoride window as low-pass filter. The transmission characteristics of the window have, therefore, a crucial impact on the detector performance. We present transmission measurements in the vacuum-ultraviolet spectral range for alkaline earth fluoride window crystals in the vicinity of the transmission cutoff as a function of crystal purity, surface finish, surface contamination,more » temperature, and thickness. Our findings reveal that the transmission characteristics of the window crystal and, thus, the detector performance depend critically on these window parameters.« less

Theoretical studies of the local structures and spin Hamiltonian parameters for Cu2+ in alkaline earth alumino borate glasses

NASA Astrophysics Data System (ADS)

Guo, Jia-Xing; Wu, Shao-Yi; Kuang, Min-Quan; Peng, Li; Wu, Li-Na

2018-01-01

The local structures and spin Hamiltonian parameters are theoretically studied for Cu2+ in alkaline earth alumino borate (XAB, X = Mg, Ca and Sr) glasses by using the perturbation calculations for tetragonally elongated octahedral 3d9 groups. The [CuO6]10- groups are subject to the large relative tetragonal elongation ratios of 15.4%, 13.4% and 13.0% for MgAB, CaAB and SrAB glasses, respectively, arising from the Jahn-Teller effect. The decreasing cubic field parameter Dq, orbital reduction factor k and relative elongation ratio with the increase of the radius of alkaline earth ion X from Mg to Ca or Sr are analyzed for the studied systems in a uniform way.

Hyperfine structure of 2Σ molecules containing alkaline-earth-metal atoms

NASA Astrophysics Data System (ADS)

Aldegunde, Jesus; Hutson, Jeremy M.

2018-04-01

Ultracold molecules with both electron spin and an electric dipole moment offer new possibilities in quantum science. We use density-functional theory to calculate hyperfine coupling constants for a selection of molecules important in this area, including RbSr, LiYb, RbYb, CaF, and SrF. We find substantial hyperfine coupling constants for the fermionic isotopes of the alkaline-earth-metal and Yb atoms. We discuss the hyperfine level patterns and Zeeman splittings expected for these molecules. The results will be important both to experiments aimed at forming ultracold open-shell molecules and to their applications.

Liquefaction process for solid carbonaceous materials containing alkaline earth metal humates

DOEpatents

Epperly, William R.; Deane, Barry C.; Brunson, Roy J.

1982-01-01

An improved liquefaction process wherein wall scale and particulate agglomeration during the liquefaction of solid carbonaceous materials containing alkaline earth metal humates is reduced and/or eliminated by subjecting the solid carbonaceous materials to controlled cyclic cavitation during liquefaction. It is important that the solid carbonaceous material be slurried in a suitable solvent or diluent during liquefaction. The cyclic cavitation may be imparted via pressure cycling, cyclic agitation and the like. When pressure cycling or the like is employed an amplitude equivalent to at least 25 psia is required to effectively remove scale from the liquefaction vessel walls.

Formation of H a - hydrogen centers upon additive coloration of alkaline-earth fluoride crystals

NASA Astrophysics Data System (ADS)

Radzhabov, E. A.; Egranov, A. V.; Shendrik, R. Yu.

2017-06-01

The mechanism of coloration of alkaline-earth fluoride crystals CaF2, SrF2, and BaF2 in calcium vapors in an autoclave with a cold zone is studied. It was found that the pressure in the autoclave upon constant evacuation by a vacuum pump within the temperature range of 500-800°C increases due to evaporation of metal calcium. In addition to the optical-absorption bands of color centers in the additively colored undoped crystals or to the bands of divalent ions in the crystals doped with rare-earth Sm, Yb, and Tm elements, there appear intense bands in the vacuum ultraviolet region at 7.7, 7.0, and 6.025 eV in CaF2, SrF2, and BaF2, respectively. These bands belong to the Ha - hydrogen centers. The formation of hydrogen centers is also confirmed by the appearance of the EPR signal of interstitial hydrogen atoms after X-ray irradiation of the additively colored crystals. Grinding of the outer edges of the colored crystals leads to a decrease in the hydrogen absorption-band intensity with depth to complete disappearance. The rate of hydrogen penetration inside the crystal is lower than the corresponding rate of color centers (anion vacancies) by a factor of tens. The visible color density of the outer regions of the hydrogen-containing crystals is several times lower than that of the inner region due to the competition between the color centers and hydrogen centers.

Health Effects of Alkaline Diet and Water, Reduction of Digestive-tract Bacterial Load, and Earthing.

PubMed

Mousa, Haider Abdul-Lateef

2016-04-01

In the article, the author discusses the issue of chronic, low-grade acidosis that is thought to be brought about primarily by 2 factors: (1) advancing age, with a consequent decline in renal function; and (2) diet. An acid-forming diet can induce low-grade metabolic acidosis, which causes very small decreases in blood pH and plasma bicarbonate (HCO3-) that remain within the range considered to be normal. However, if the duration of the acidosis is prolonged or chronically present, even a low degree of acidosis can become significant. This article reviews supporting evidence in the literature that has shown that consumption of abundant alkaline-forming foods can result in improvement in bone mineral density (BMD) and muscle mass, protection from chronic illnesses, reduced tumor-cell invasion and metastasis, and effective excretion of toxins from the body. In addition, a large number of studies showing the benefits of alkaline water (mineral water) have revealed that people consuming water with a high level of total dissolved solids (TDS) (ie, with a high mineral content) have shown a lower incidence of coronary heart disease (CHD), cardiovascular disease (CVD), and cancer and lower total mortality rates. Consumption of alkaline water also may prevent osteoporosis and protect pancreatic beta cells with its antioxidant effects. In addition, this article discusses the literature that shows that reducing digestive-tract bacterial load can play an important role in increasing blood alkalinity toward the normal upper limit. That change occurs through good oral hygiene, flossing of teeth, perfect chewing of food, and bowel evacuation as soon as possible. Finally, the author reviews the literature that shows that earthing (ie, the direct contact of the human body with the earth) can supply a current of plentiful electrons. Earthing has been shown to reduce acute and chronic inflammation, blood glucose in patients with diabetes, red blood cell (RBC) aggregation, and blood

Bioleaching of rare earth elements from monazite sand.

PubMed

Brisson, Vanessa L; Zhuang, Wei-Qin; Alvarez-Cohen, Lisa

2016-02-01

Three fungal strains were found to be capable of bioleaching rare earth elements from monazite, a rare earth phosphate mineral, utilizing the monazite as a phosphate source and releasing rare earth cations into solution. These organisms include one known phosphate solubilizing fungus, Aspergillus niger ATCC 1015, as well as two newly isolated fungi: an Aspergillus terreus strain ML3-1 and a Paecilomyces spp. strain WE3-F. Although monazite also contains the radioactive element Thorium, bioleaching by these fungi preferentially solubilized rare earth elements over Thorium, leaving the Thorium in the solid residual. Adjustments in growth media composition improved bioleaching performance measured as rare earth release. Cell-free spent medium generated during growth of A. terreus strain ML3-1 and Paecilomyces spp. strain WE3-F in the presence of monazite leached rare earths to concentrations 1.7-3.8 times those of HCl solutions of comparable pH, indicating that compounds exogenously released by these organisms contribute substantially to leaching. Organic acids released by the organisms included acetic, citric, gluconic, itaconic, oxalic, and succinic acids. Abiotic leaching with laboratory prepared solutions of these acids was not as effective as bioleaching or leaching with cell-free spent medium at releasing rare earths from monazite, indicating that compounds other than the identified organic acids contribute to leaching performance. © 2015 Wiley Periodicals, Inc.

Gaussian basis sets for use in correlated molecular calculations. XI. Pseudopotential-based and all-electron relativistic basis sets for alkali metal (K-Fr) and alkaline earth (Ca-Ra) elements

NASA Astrophysics Data System (ADS)

Hill, J. Grant; Peterson, Kirk A.

2017-12-01

New correlation consistent basis sets based on pseudopotential (PP) Hamiltonians have been developed from double- to quintuple-zeta quality for the late alkali (K-Fr) and alkaline earth (Ca-Ra) metals. These are accompanied by new all-electron basis sets of double- to quadruple-zeta quality that have been contracted for use with both Douglas-Kroll-Hess (DKH) and eXact 2-Component (X2C) scalar relativistic Hamiltonians. Sets for valence correlation (ms), cc-pVnZ-PP and cc-pVnZ-(DK,DK3/X2C), in addition to outer-core correlation [valence + (m-1)sp], cc-p(w)CVnZ-PP and cc-pwCVnZ-(DK,DK3/X2C), are reported. The -PP sets have been developed for use with small-core PPs [I. S. Lim et al., J. Chem. Phys. 122, 104103 (2005) and I. S. Lim et al., J. Chem. Phys. 124, 034107 (2006)], while the all-electron sets utilized second-order DKH Hamiltonians for 4s and 5s elements and third-order DKH for 6s and 7s. The accuracy of the basis sets is assessed through benchmark calculations at the coupled-cluster level of theory for both atomic and molecular properties. Not surprisingly, it is found that outer-core correlation is vital for accurate calculation of the thermodynamic and spectroscopic properties of diatomic molecules containing these elements.

Membrane assisted solvent extraction for rare earth element recovery

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

Bhave, Ramesh R.; Kim, Daejin; Peterson, Eric S.

Systems and methods for the recovery of rare earth elements are provided. The systems and methods generally include membrane assisted solvent extraction using permeable hollow fibers having an immobilized organic phase within the pores of the hollow fibers. The permeable hollow fibers are generally in contact with an acidic aqueous feed on one side thereof and a strip solution on another side thereof. The systems and methods generally include the simultaneous extraction and stripping of rare earth elements as a continuous recovery process that is well suited for post-consumer products, end-of-life products, and other recovery sources of rare earth elements.

Studies on the interactions between purified bovine caseins and alkaline-earth-metalions

PubMed Central

Dickson, I. R.; Perkins, D. J.

1971-01-01

1. Alkaline-earth-metal cations at low concentrations form soluble complexes with bovine caseins. The relative order of binding capacities is: Mg2+>Ca2+>Ba2+>Sr2+. 2. The cations interact with both free ionized carboxyl groups of aspartic acid and glutamic acid and with monoester phosphate groups covalently bound to serine and threonine; at low concentrations of the cations interactions are predominantly with the phosphate groups. 3. The order of binding capacities for purified components of the casein complex is: αs1-casein>β-casein>κ-casein. PMID:5166590

Enhanced phytoextraction of germanium and rare earth elements - a rhizosphere-based approach

NASA Astrophysics Data System (ADS)

Wiche, Oliver

2016-04-01

Germanium (Ge) and rare earth elements (REEs) are economically valuable raw materials that have become an integral part of our modern high tech society. While most of these elements are not actually rare in terms of general amounts in the earth's crust, they are rarely found in sufficient abundances in single locations for their mining to be economically viable. The average concentration of Ge in soils is estimated at 1.6 μg g-1. The REEs comprise a group of 16 elements including La, the group of lanthanides and Y that are abundant in the earth crust with concentrations varying from 35 μg g-1 (La), 40 μg g-1 (Nd), 6 μg g-1 (Gd) and 3.5 μg g-1 (Er) to 0.5 μg g-1 in Tm. Thus, a promising chance to improve supply of these elements could be phytomining. Unfortunately, bioavailability of Ge and REEs in soils appears to be low, in particular in neutral or alkaline soils. A sequential dissolution analysis of 120 soil samples taken from the A-horizons of soils in the area of Freiberg (Saxony, Germany) revealed that only 0.2% of total Ge and about 0.5% of La, Nd, Gd and Er of bulk concentrations were easily accessible by leaching with NH4-acetate (pH 7). Most of the investigated elements were bound to Fe-/Mn-oxides and silicates and were therefore only poorly available for plant uptake. Here we report an environmentally friendly approach for enhanced phytoextraction of Ge and REEs from soils using mixed cultures of plant species with efficient mechanisms for the acquisition of nutrients in the rhizosphere. The rhizosphere is characterized as the zone in soil sourrounding a plant root that consists of a gradient in chemical, physical and biological soil properties driven by rhizodeposits like carboxylates and protons. Some species like white lupin (Lupinus albus) are able to excrete large amounts of organic acid anions(predominantly citrate and malate) and show a particularly high potential for the acidification of the rhizosphere. In our experiments, mixed cultures

How PNNL Extracts Rare Earth Elements from Geothermal Brine

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

None

2016-07-12

By looking at a problem at a nanoscale level, PNNL researchers are developing an economic way to extract valuable rare earth elements from geothermal fluids. This novel approach may help meet the high demand for rare earth elements that are used in many clean energy technologies.

Rare Earth Element Partition Coefficients from Enstatite/Melt Synthesis Experiments

NASA Technical Reports Server (NTRS)

Schwandt, Craig S.; McKay, Gordon A.

1997-01-01

Enstatite (En(80)Fs(19)Wo(01)) was synthesized from a hypersthene normative basaltic melt doped at the same time with La, Ce, Nd, Sm, Eu, Dy, Er, Yb and Lu. The rare earth element concentrations were measured in both the basaltic glass and the enstatite. Rare earth element concentrations in the glass were determined by electron microprobe analysis with uncertainties less than two percent relative. Rare earth element concentrations in enstatite were determined by secondary ion mass spectrometry with uncertainties less than five percent relative. The resulting rare earth element partition signature for enstatite is similar to previous calculated and composite low-Ca pigeonite signatures, but is better defined and differs in several details. The partition coefficients are consistent with crystal structural constraints.

Wide-band-gap, alkaline-earth-oxide semiconductor and devices utilizing same

DOEpatents

Abraham, Marvin M.; Chen, Yok; Kernohan, Robert H.

1981-01-01

This invention relates to novel and comparatively inexpensive semiconductor devices utilizing semiconducting alkaline-earth-oxide crystals doped with alkali metal. The semiconducting crystals are produced by a simple and relatively inexpensive process. As a specific example, a high-purity lithium-doped MgO crystal is grown by conventional techniques. The crystal then is heated in an oxygen-containing atmosphere to form many [Li].degree. defects therein, and the resulting defect-rich hot crystal is promptly quenched to render the defects stable at room temperature and temperatures well above the same. Quenching can be effected conveniently by contacting the hot crystal with room-temperature air.

The Effect of Alkaline Earth Metal on the Cesium Loading of Ionsiv(R) IE-910 and IE-911

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

Fondeur, F.F.

2001-01-16

This study investigated the effect of variances in alkaline earth metal concentrations on cesium loading of IONSIV(R) IE-911. The study focused on Savannah River Site (SRS) ''average'' solution with varying amounts of calcium, barium and magnesium.

Core-Mantle Partitioning of Volatile Siderophile Elements and the Origin of Volatile Elements in the Earth

NASA Technical Reports Server (NTRS)

Nickodem, K.; Righter, K.; Danielson, L.; Pando, K.; Lee, C.

2012-01-01

There are currently several hypotheses on the origin of volatile siderophile elements in the Earth. One hypothesis is that they were added during Earth s accretion and core formation and mobilized into the metallic core [1], others claim multiple stage origin [2], while some hypothesize that volatiles were added after the core already formed [3]. Several volatile siderophile elements are depleted in Earth s mantle relative to the chondrites, something which continues to puzzle many scientists. This depletion is likely due to a combination of volatility and core formation. The Earth s core is composed of Fe and some lighter constituents, although the abundances of these lighter elements are unknown [4]. Si is one of these potential light elements [5] although few studies have analyzed the effect of Si on metal-silicate partitioning, in particular the volatile elements. As, In, Ge, and Sb are trace volatile siderophile elements which are depleted in the mantle but have yet to be extensively studied. The metal-silicate partition coefficients of these elements will be measured to determine the effect of Si. Partition coefficients depend on temperature, pressure, oxygen fugacity, and metal and silicate composition and can constrain the concentrations of volatile, siderophile elements found in the mantle. Reported here are the results from 13 experiments examining the partitioning of As, In, Ge, and Sb between metallic and silicate liquid. These experiments will examine the effect of temperature, and metal-composition (i.e., Si content) on these elements in or-der to gain a greater understanding of the core-mantle separation which occurred during the Earth s early stages. The data can then be applied to the origin of volatile elements in the Earth.

Scarcity of rare earth elements.

PubMed

de Boer, M A; Lammertsma, K

2013-11-01

Rare earth elements (REEs) are important for green and a large variety of high-tech technologies and are, therefore, in high demand. As a result, supply with REEs is likely to be disrupted (the degree of depends on the REE) in the near future. The 17 REEs are divided into heavy and light REEs. Other critical elements besides REEs, identified by the European Commission, are also becoming less easily available. Although there is no deficiency in the earth's crust of rare earth oxides, the economic accessibility is limited. The increased demand for REEs, the decreasing export from China, and geopolitical concerns on availability contributed to the (re)opening of mines in Australia and the USA and other mines are slow to follow. As a result, short supply of particularly terbium, dysprosium, praseodymium, and neodymium is expected to be problematic for at least the short term, also because they cannot be substituted. Recycling REEs from electronic waste would be a solution, but so far there are hardly any established REE recycling methods. Decreasing the dependency on REEs, for example, by identifying possible replacements or increasing their efficient use, represents another possibility. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Coordination chemistry of vitamin C. Part I. Interaction of L-ascorbic acid with alkaline earth metal ions in the crystalline solid and aqueous solution.

PubMed

Tajmir-Riahi, H A

1990-10-01

The interaction of L-ascorbic acid with alkaline earth metal ions has been investigated in aqueous solution at pH 6-7. The solid salts of the type Mg(L-ascorbate)2.4H2O, Ca(L-ascorbate)2.2H2O, Sr(L-ascorbate)2.2H2O and Ba(L-ascorbate)2.2H2O were isolated and characterized by means of 13C NMR and FT-IR spectroscopy. Spectroscopic and other evidence suggested that in aqueous solution, the binding of the alkaline earth metal ions is through the O-3 atom of the ascorbate anion, while in the solid state the binding of the Mg(II) is different from those of the other alkaline earth metal ion salts. The Mg(II) ion binds to the O-3, O-1 atom of the two ascorbate anions and to two H2O molecules, while the eight-coordination around the Ca(II), Sr(II), and Ba(II) ions would be completed by the coordination of three acid anions, through O-5, O-6 of the first, O-3, O-5, O-6 of the second and O-1 of the third anion as well as to two H2O molecules. The structural properties of the alkaline earth metal-ascorbate salts are different in the solid and aqueous solution.

Alkali and alkaline earth metal salts of tetrazolone: structurally interesting and excellently thermostable.

PubMed

He, Piao; Wu, Le; Wu, Jin-Ting; Yin, Xin; Gozin, Michael; Zhang, Jian-Guo

2017-07-04

Tetrazolone (5-oxotetrazole) was synthesized by a moderate strategy through three steps (addition, cyclization and catalytic hydrogenation) avoiding the unstable intermediate diazonium, as reported during the previous preparation. Alkali and alkaline earth metal salts with lithium (1), sodium (2), potassium (3), rubidium (4) caesium (5), magnesium (6), calcium (7), strontium (8) and barium (9) were prepared and fully characterized using elemental analysis, IR and NMR spectroscopy, DSC and TG analysis. All metal salts were characterized via single-crystal X-ray diffraction. They crystallize in common space groups with high densities ranging from 1.479 (1) to 3.060 g cm -3 (5). Furthermore, the crystal structures of 7, 8 and 9 reveal interesting porous energetic coordination polymers with strong hydrogen bond interactions. All new salts have good thermal stabilities with decomposition temperature between 215.0 °C (4) and 328.2 °C (7), significantly higher than that of the reported nitrogen-rich salt neutral tetrazolone. The sensitivities towards impact and friction were tested using standard methods, and all the tetrazolone-based compounds investigated can be classified into insensitive. The flame test of these metal salts supports their potential use as perchlorate-free pyrotechnics or eco-friendly insensitive energetic materials.

Accumulation of rare earth elements by siderophore-forming Arthrobacter luteolus isolated from rare earth environment of Chavara, India.

PubMed

Emmanuel, E S Challaraj; Ananthi, T; Anandkumar, B; Maruthamuthu, S

2012-03-01

In this study, Arthrobacter luteolus, isolated from rare earth environment of Chavara (Quilon district, Kerala, India), were found to produce catechol-type siderophores. The bacterial strain accumulated rare earth elements such as samarium and scandium. The siderophores may play a role in the accumulation of rare earth elements. Catecholate siderophore and low-molecular-weight organic acids were found to be present in experiments with Arthrobacter luteolus. The influence of siderophore on the accumulation of rare earth elements by bacteria has been extensively discussed.

Effect of high-energy electron irradiation in an electron microscope column on fluorides of alkaline earth elements (CaF2, SrF2, and BaF2)

NASA Astrophysics Data System (ADS)

Nikolaichik, V. I.; Sobolev, B. P.; Zaporozhets, M. A.; Avilov, A. S.

2012-03-01

The effect of high-energy (150 eV) electron irradiation in an electron microscope column on crystals of fluorides of alkaline earth elements CaF2, SrF2, and BaF2 is studied. During structural investigations by electron diffraction and electron microscopy, the electron irradiation causes chemical changes in MF2 crystals such as the desorption of fluorine and the accumulation of oxygen in the irradiated area with the formation of oxide MO. The fluorine desorption rate increases significantly when the electron-beam density exceeds the threshold value of ˜2 × 103 pA/cm2). In BaF2 samples, the transformation of BaO into Ba(OH)2 was observed when irradiation stopped. The renewal of irradiation is accompanied by the inverse transformation of Ba(OH)2 into BaO. In the initial stage of irradiation of all MF2 compounds, the oxide phase is in the single-crystal state with a lattice highly matched with the MF2 matrix. When the irradiation dose is increased, the oxide phase passes to the polycrystalline phase. Gaseous products of MF2 destruction (in the form of bubbles several nanometers in diameter) form a rectangular array with a period of ˜20 nm in the sample.

A deposit model for carbonatite and peralkaline intrusion-related rare earth element deposits: Chapter J in Mineral deposit models for resource assessment

USGS Publications Warehouse

Verplanck, Philip L.; Van Gosen, Bradley S.; Seal, Robert R.; McCafferty, Anne E.

2014-01-01

The greatest environmental challenges associated with carbonatite and peralkaline intrusion-related rare earth element deposits center on the associated uranium and thorium. Considerable uncertainty exists around the toxicity of rare earth elements and warrants further investigation. The acid-generating potential of carbonatites and peralkaline intrusion-related deposits is low due to the dominance of carbonate minerals in carbonatite deposits, the presence of feldspars and minor calcite within the alkaline intrusion deposits, and only minor quantities of potentially acid-generating sulfides. Therefore, acid-drainage issues are not likely to be a major concern associated with these deposits. Uranium has the potential to be recovered as a byproduct, which would mitigate some of its environmental effects. However, thorium will likely remain a waste-stream product that will require management since progress is not being made towards the development of thorium-based nuclear reactors in the United States or other large scale commercial uses. Because some deposits are rich in fluorine and beryllium, these elements may be of environmental concern in certain locations.

Theoretical dissociation energies for the alkali and alkaline-earth monofluorides and monochlorides

NASA Technical Reports Server (NTRS)

Langhoff, S. R.; Bauschlicher, C. W., Jr.; Partridge, H.

1986-01-01

Spectroscopic parameters are accurately determined for the alkali and alkaline-earth monofluorides and monochlorides by means of ab initio self-consistent field and correlated wave function calculations. Numerical Hartree-Fock calculations are performed on selected systems to ensure that the extended Slater basis sets employed are near the Hartree-Fock limit. Since the bonding is predominantly electrostatic in origin, a strong correlation exists between the dissociation energy (to ions) and the spectroscopic parameter r(e). By dissociating to the ionic limits, most of the differential correlation effects can be embedded in the accurate experimental electron affinities and ionization potentials.

An easy access to nanocrystalline alkaline earth metal fluorides - just by shaking

NASA Astrophysics Data System (ADS)

Dreger, M.; Scholz, G.; Kemnitz, E.

2012-04-01

High energy ball milling as fast, direct and solvent free method allows an easy access to nanocrystalline alkaline earth metal fluorides MF2 (M: Mg, Ca, Sr, Ba). Comparable metal sources (acetates, carbonates, hydroxides, alkoxides) were used for the reaction with NH4F as fluorinating agent. Even very simple manual shaking experiments between NH4F and the corresponding hydroxides in the stoichiometric ratio (M:F = 1:2, M: Ca, Sr, Ba) give phase pure fluorides. Moreover, comparable classical thermal reactions in closed crucibles at higher temperatures provide phase pure crystalline fluorides in nearly all cases as well.

Rare earth element recycling from waste nickel-metal hydride batteries.

PubMed

Yang, Xiuli; Zhang, Junwei; Fang, Xihui

2014-08-30

With an increase in number of waste nickel-metal hydride batteries, and because of the importance of rare earth elements, the recycling of rare earth elements is becoming increasingly important. In this paper, we investigate the effects of temperature, hydrochloric acid concentration, and leaching time to optimize leaching conditions and determine leach kinetics. The results indicate that an increase in temperature, hydrochloric acid concentration, and leaching time enhance the leaching rate of rare earth elements. A maximum rare earth elements recovery of 95.16% was achieved at optimal leaching conditions of 70°C, solid/liquid ratio of 1:10, 20% hydrochloric acid concentration, -74μm particle size, and 100min leaching time. The experimental data were best fitted by a chemical reaction-controlled model. The activation energy was 43.98kJ/mol and the reaction order for hydrochloric acid concentration was 0.64. The kinetic equation for the leaching process was found to be: 1-(1-x)(1/3)=A/ρr0[HCl](0.64)exp-439,8008.314Tt. After leaching and filtration, by adding saturated oxalic solution to the filtrate, rare earth element oxalates were obtained. After removing impurities by adding ammonia, filtering, washing with dilute hydrochloric acid, and calcining at 810°C, a final product of 99% pure rare earth oxides was obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

Theoretical study of the dipole moments of selected alkaline-earth halides

NASA Technical Reports Server (NTRS)

Langhoff, S. R.; Bauschlicher, C. W., Jr.; Partridge, H.; Ahlrichs, R.

1986-01-01

Ab initio calculations at the self-consistent-field (SCF), singles-plus-doubles configuration-interaction (SDCI), and coupled-pair functional (CPF) level, are reported for the dipole moments and dipole derivatives of the X2Sigma(+) ground states of BeF, BeCl, MgF, MgCl, CaF, CaCl, and SrF. For comparison, analogous calculations are performed for the X1Sigma(+) state of KCl. The CPF results are found to be in remarkably better agreement with experiment than are the SCF and SDCI results. Apparently higher excitations are required to properly describe the radial extent along the bond axis of the remaining valence electron on the alkaline-earth metal.

Model of Silicon Refining During Tapping: Removal of Ca, Al, and Other Selected Element Groups

NASA Astrophysics Data System (ADS)

Olsen, Jan Erik; Kero, Ida T.; Engh, Thorvald A.; Tranell, Gabriella

2017-04-01

A mathematical model for industrial refining of silicon alloys has been developed for the so-called oxidative ladle refining process. It is a lumped (zero-dimensional) model, based on the mass balances of metal, slag, and gas in the ladle, developed to operate with relatively short computational times for the sake of industrial relevance. The model accounts for a semi-continuous process which includes both the tapping and post-tapping refining stages. It predicts the concentrations of Ca, Al, and trace elements, most notably the alkaline metals, alkaline earth metal, and rare earth metals. The predictive power of the model depends on the quality of the model coefficients, the kinetic coefficient, τ, and the equilibrium partition coefficient, L for a given element. A sensitivity analysis indicates that the model results are most sensitive to L. The model has been compared to industrial measurement data and found to be able to qualitatively, and to some extent quantitatively, predict the data. The model is very well suited for alkaline and alkaline earth metals which respond relatively fast to the refining process. The model is less well suited for elements such as the lanthanides and Al, which are refined more slowly. A major challenge for the prediction of the behavior of the rare earth metals is that reliable thermodynamic data for true equilibrium conditions relevant to the industrial process is not typically available in literature.

Ab initio study of the neutral and anionic alkali and alkaline earth hydroxides: Electronic structure and prospects for sympathetic cooling of OH−

PubMed Central

2017-01-01

We have performed a systematic ab initio study on alkali and alkaline earth hydroxide neutral (MOH) and anionic (MOH−) species where M = Li, Na, K, Rb, Cs or Be, Mg, Ca, Sr, Ba. The CCSD(T) method with extended basis sets and Dirac-Fock relativistic effective core potentials for the heavier atoms has been used to study their equilibrium geometries, interaction energies, electron affinities, electric dipole moment, and potential energy surfaces. All neutral and anionic species exhibit a linear shape with the exception of BeOH, BeOH−, and MgOH−, for which the equilibrium structure is found to be bent. Our analysis shows that the alkaline earth hydroxide anions are valence-bound whereas the alkali hydroxide anions are dipole bound. In the context of sympathetic cooling of OH− by collision with ultracold alkali and alkaline earth atoms, we investigate the 2D MOH− potential energy surfaces and the associative detachment reaction M + OH→− MOH + e−, which is the only energetically allowed reactive channel in the cold regime. We discuss the implication for the sympathetic cooling of OH− and conclude that Li and K are the best candidates for an ultracold buffer gas. PMID:28527437

Biogeochemistry of the rare-earth elements with particular reference to hickory trees

USGS Publications Warehouse

Robinson, W.O.; Bastron, H.; Murata, K.J.

1958-01-01

Hickory trees concentrate the rare-earth elements in their leaves to a phenomenal degree and may contain as much as 2300 p.p.m. of total rare earths based on the dry weight of the leaves. The average proportions of the individual elements (atomic percent of the total rare-earth elements) in the leaves are: Y 36, La 16, Ce 14, Pr 2, Nd 20, Sm 1, Eu 0.7, Gd 3, Tb 0.6, Dy 3, Ho 0.7, Er 2, Tm 0.2, Yb 1, and Lu 0.2. The similarity in the proportions of the rare-earth elements in the leaves and in the exchange complex of the soil on which the hickory trees grow indicates that the trees do not fractionate the rare earths appreciably. The variation of the rare-earth elements in the leaves and soils can be explained generally in terms of the relative abundance of the cerium group and the yttrium group, except for the element cerium. The large fluctuations in the proportion of cerium [Ce/(La + Nd) atomic ratios of 0.16 to 0.86] correlate with oxidation-reduction conditions in the soil profile. The substitution of dilute H2SO3 for dilute HC1 in the determination of available rare-earth elements brings about a large increase in the proportion of cerium that is extracted from an oxygenated subsoil. These relationships strongly suggest that quadrivalent cerium is present in oxygenated subsoil and is less available to plants than the other rare-earth elements that do not undergo such a change in valence. A few parts per billion of rare-earth elements have been detected in two samples of ground water. ?? 1958.

New stable ternary alkaline-earth metal Pb(II) oxides: Ca / Sr / BaPb 2 O 3 and BaPbO 2

DOE PAGES

Li, Yuwei; Zhang, Lijun; Singh, David J.

2017-10-16

The different but related chemical behaviors of Pb(II) oxides compared to Sn(II) oxides, and the existence of known alkali/alkali-earth metal Sn(II) ternary phases, suggest that there should be additional ternary Pb(II) oxide phases. Here, we report structure searches on the ternary alkaline-earth metal Pb(II) oxides leading to four new phases. These are two ternary Pb(II) oxides, SrPb 2O 3 and BaPb 2O 3, which have larger chemical potential stability ranges compared with the corresponding Sn(II) oxides, and additionally two other ternary Pb(II) oxides, CaPb 2O 3 and BaPbO 2, for which there are no corresponding Sn(II) oxides. Those Pb(II) oxidesmore » are stabilized by Pb-rich conditions. These structures follow the Zintl behavior and consist of basic structural motifs of (PbO 3) 4- anionic units separated and stabilized by the alkaline-earth metal ions. They show wide band gaps ranging from 2.86 to 3.12 eV, and two compounds (CaPb 2O 3 and SrPb 2O 3) show rather light hole effective masses (around 2m 0). The valence band maxima of these compounds have a Pb-6s/O-2p antibonding character, which may lead to p-type defect (or doping) tolerant behavior. This then suggests alkaline-earth metal Pb(II) oxides may be potential p-type transparent conducting oxides.« less

New stable ternary alkaline-earth metal Pb(II) oxides: Ca / Sr / BaPb 2 O 3 and BaPbO 2

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

Li, Yuwei; Zhang, Lijun; Singh, David J.

The different but related chemical behaviors of Pb(II) oxides compared to Sn(II) oxides, and the existence of known alkali/alkali-earth metal Sn(II) ternary phases, suggest that there should be additional ternary Pb(II) oxide phases. Here, we report structure searches on the ternary alkaline-earth metal Pb(II) oxides leading to four new phases. These are two ternary Pb(II) oxides, SrPb 2O 3 and BaPb 2O 3, which have larger chemical potential stability ranges compared with the corresponding Sn(II) oxides, and additionally two other ternary Pb(II) oxides, CaPb 2O 3 and BaPbO 2, for which there are no corresponding Sn(II) oxides. Those Pb(II) oxidesmore » are stabilized by Pb-rich conditions. These structures follow the Zintl behavior and consist of basic structural motifs of (PbO 3) 4- anionic units separated and stabilized by the alkaline-earth metal ions. They show wide band gaps ranging from 2.86 to 3.12 eV, and two compounds (CaPb 2O 3 and SrPb 2O 3) show rather light hole effective masses (around 2m 0). The valence band maxima of these compounds have a Pb-6s/O-2p antibonding character, which may lead to p-type defect (or doping) tolerant behavior. This then suggests alkaline-earth metal Pb(II) oxides may be potential p-type transparent conducting oxides.« less

Anthropogenic disturbance of element cycles at the Earth's surface.

PubMed

Sen, Indra S; Peucker-Ehrenbrink, Bernhard

2012-08-21

The extent to which humans are modifying Earth's surface chemistry can be quantified by comparing total anthropogenic element fluxes with their natural counterparts (Klee and Graedel, 2004). We quantify anthropogenic mass transfer of 77 elements from mining, fossil fuel burning, biomass burning, construction activities, and human apportionment of terrestrial net primary productivity, and compare it to natural mass transfer from terrestrial and marine net primary productivity, riverine dissolved and suspended matter fluxes to the ocean, soil erosion, eolian dust, sea-salt spray, cosmic dust, volcanic emissions, and for helium, hydrodynamic escape from the Earth's atmosphere. We introduce an approach to correct for losses during industrial processing of elements belonging to geochemically coherent groups, and explicitly incorporate uncertainties of element mass fluxes through Monte Carlo simulations. We find that at the Earth's surface anthropogenic fluxes of iridium, osmium, helium, gold, ruthenium, antimony, platinum, palladium, rhenium, rhodium and chromium currently exceed natural fluxes. For these elements mining is the major factor of anthropogenic influence, whereas petroleum burning strongly influences the surficial cycle of rhenium. Our assessment indicates that if anthropogenic contributions to soil erosion and eolian dust are considered, anthropogenic fluxes of up to 62 elements surpass their corresponding natural fluxes.

Interatomic Potentials for Structure Simulation of Alkaline-Earth Cuprates

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

Eremin, N.N.; Leonyuk, L.I.; Urusov, V.S.

2001-05-01

A specific potential model of interionic interactions was derived in which the crystal structures of alkaline-earth cuprates were satisfactorily described and some of their physical properties were predicted. It was found that a harmonic three-particle O-Cu-O potential and some Morse-type contributions to the simple Buckingham-type Cu-O repulsive potential enable one to improve essentially the results of crystal structure modeling for cuprates. The obtained potential set seems to be well transferable for different cuprates, despite the variety in linkages of the CuO{sub 4} groups. In the present work this potential set model was applied in the crystal structure modeling for Ca{submore » 2}CuO{sub 3}, CaCuO{sub 2}, SrCuO{sub 3}, (Sr{sub 1.19}Ca{sub 0.73})Cu{sub 2}O{sub 4}, and BaCuO{sub 2}. Some elastic and energetic properties of the compounds under question were predicted.« less

Core-Mantle Partitioning of Volatile Elements and the Origin of Volatile Elements in Earth and Moon

NASA Technical Reports Server (NTRS)

Righter, Kevin; Pando, K.; Danielson, L.; Nickodem, K.

2014-01-01

Depletions of volatile siderophile elements (VSE; Ga, Ge, In, As, Sb, Sn, Bi, Zn, Cu, Cd) in mantles of Earth and Moon, constrain the origin of volatile elements in these bodies, and the overall depletion of volatile elements in Moon relative to Earth. A satisfactory explanation has remained elusive [1,2]. We examine the depletions of VSE in Earth and Moon and quantify the amount of depletion due to core formation and volatility of potential building blocks. We calculate the composition of the Earth's PUM during continuous accretion scenarios with constant and variable fO2. Results suggest that the VSE can be explained by a rather simple scenario of continuous accretion leading to a high PT metal-silicate equilibrium scenario that establishes the siderophile element content of Earth's PUM near the end of accretion [3]. Core formation models for the Moon explain most VSE, but calculated contents of In, Sn, and Zn (all with Tc < 750 K) are all still too high after core formation, and must therefore require an additional process to explain the depletions in the lunar mantle. We discuss possible processes including magmatic degassing, evaporation, condensation, and vapor-liquid fractionation in the lunar disk.

Rare earth element deposits in China

USGS Publications Warehouse

Xie, Yu-Ling; Hou, Zeng-qian; Goldfarb, Richard J.; Guo, Xiang; Wang, Lei

2016-01-01

China is the world’s leading rare earth element (REE) producer and hosts a variety of deposit types. Carbonatite- related REE deposits, the most significant deposit type, include two giant deposits presently being mined in China, Bayan Obo and Maoniuping, the first and third largest deposits of this type in the world, respectively. The carbonatite-related deposits host the majority of China’s REE resource and are the primary supplier of the world’s light REE. The REE-bearing clay deposits, or ion adsorption-type deposits, are second in importance and are the main source in China for heavy REE resources. Other REE resources include those within monazite or xenotime placers, beach placers, alkaline granites, pegmatites, and hydrothermal veins, as well as some additional deposit types in which REE are recovered as by-products. Carbonatite-related REE deposits in China occur along craton margins, both in rifts (e.g., Bayan Obo) and in reactivated transpressional margins (e.g., Maoniuping). They comprise those along the northern, eastern, and southern margins of the North China block, and along the western margin of the Yangtze block. Major structural features along the craton margins provide first-order controls for REE-related Proterozoic to Cenozoic carbonatite alkaline complexes; these are emplaced in continental margin rifts or strike-slip faults. The ion adsorption-type REE deposits, mainly situated in the South China block, are genetically linked to the weathering of granite and, less commonly, volcanic rocks and lamprophyres. Indosinian (early Mesozoic) and Yanshanian (late Mesozoic) granites are the most important parent rocks for these REE deposits, although Caledonian (early Paleozoic) granites are also of local importance. The primary REE enrichment is hosted in various mineral phases in the igneous rocks and, during the weathering process, the REE are released and adsorbed by clay minerals in the weathering profile. Currently, these REE-rich clays are

Contemporaneous alkaline and calc-alkaline series in Central Anatolia (Turkey): Spatio-temporal evolution of a post-collisional Quaternary basaltic volcanism

NASA Astrophysics Data System (ADS)

Dogan-Kulahci, Gullu Deniz; Temel, Abidin; Gourgaud, Alain; Varol, Elif; Guillou, Hervé; Deniel, Catherine

2018-05-01

This study focuses on spatio-temporal evolution of basaltic volcanism in the Central Anatolian post-collisional Quaternary magmatic province which developed along a NE-SW orientation in Turkey. This magmatic province consists of the stratovolcanoes Erciyes (ES) and Hasandag (HS), and the basaltic volcanic fields of Obruk-Zengen (OZ) and Karapınar (KA). The investigated samples range between basic to intermediate in composition (48-56 wt% SiO2), and exhibit calc-alkaline affinity at ES whereas HS, OZ and KA are alkaline in composition. Based on new Ksbnd Ar ages and major element data, the oldest basaltic rock of ES is 1700 ± 40 ka old and exhibits alkaline character, whereas the youngest basaltic trachyandesite is 12 ± 5 ka old and calc-alkaline in composition. Most ES basaltic rocks are younger than 350 ka. All samples dated from HS are alkaline basalts, ranging from 543 ± 12 ka to 2 ± 7 ka old. With the exception of one basalt, all HS basalts are 100 ka or younger in age. Ksbnd Ar ages range from 797 ± 20 ka to 66 ± 7 ka from OZ. All the basalt samples are alkaline in character and are older than the HS alkaline basalts, with the exception of the youngest samples. The oldest and youngest basaltic samples from KA are 280 ± 7 ka and 163 ± 10 ka, respectively, and are calc-alkaline in character. Based on thermobarometric estimates samples from OZ exhibit the highest cpx-liqidus temperature and pressure. For all centers the calculated crystallization depths are between 11 and 28 km and increase from NE to SW. Multistage crystallization in magma chamber(s) located at different depths can explain this range in pressure. Harker variation diagrams coupled with least-squares mass balance calculations support fractional crystallization for ES and, to lesser extend for HS, OZ and KA. All basaltic volcanic rocks of this study are enriched in large-ion lithophile elements (LILE) and light rare earth elements (LREE). The lack of negative anomalies for high field

Earth, Air, Fire and Water in Our Elements

ERIC Educational Resources Information Center

Lievesley, Tara

2007-01-01

The idea that everything is made of the four "elements", earth, air, fire and water, goes back to the ancient Greeks. In this article, the author talks about the origins of ideas about the elements. The author provides an account that attempts to summarise thousands of years of theoretical development of the elements in a thousand words or so.

The elemental abundances (with uncertainties) of the most Earth-like planet

NASA Astrophysics Data System (ADS)

Wang, Haiyang S.; Lineweaver, Charles H.; Ireland, Trevor R.

2018-01-01

To first order, the Earth as well as other rocky planets in the Solar System and rocky exoplanets orbiting other stars, are refractory pieces of the stellar nebula out of which they formed. To estimate the chemical composition of rocky exoplanets based on their stellar hosts' elemental abundances, we need a better understanding of the devolatilization that produced the Earth. To quantify the chemical relationships between the Earth, the Sun and other bodies in the Solar System, the elemental abundances of the bulk Earth are required. The key to comparing Earth's composition with those of other objects is to have a determination of the bulk composition with an appropriate estimate of uncertainties. Here we present concordance estimates (with uncertainties) of the elemental abundances of the bulk Earth, which can be used in such studies. First we compile, combine and renormalize a large set of heterogeneous literature values of the primitive mantle (PM) and of the core. We then integrate standard radial density profiles of the Earth and renormalize them to the current best estimate for the mass of the Earth. Using estimates of the uncertainties in i) the density profiles, ii) the core-mantle boundary and iii) the inner core boundary, we employ standard error propagation to obtain a core mass fraction of 32.5 ± 0.3 wt%. Our bulk Earth abundances are the weighted sum of our concordance core abundances and concordance PM abundances. Unlike previous efforts, the uncertainty on the core mass fraction is propagated to the uncertainties on the bulk Earth elemental abundances. Our concordance estimates for the abundances of Mg, Sn, Br, B, Cd and Be are significantly lower than previous estimates of the bulk Earth. Our concordance estimates for the abundances of Na, K, Cl, Zn, Sr, F, Ga, Rb, Nb, Gd, Ta, He, Ar, and Kr are significantly higher. The uncertainties on our elemental abundances usefully calibrate the unresolved discrepancies between standard Earth models under

Monitoring of photoluminescence decay by alkali and alkaline earth metal cations using a photoluminescent bolaamphiphile self-assembly as an optical probe.

PubMed

Kim, Sunhyung; Kwak, Jinyoung; Lee, Sang-Yup

2014-05-01

Photoluminescence (PL) decay induced by the displacement of an ionic fluorescence component, Tb(3+), with alkali and alkaline earth metal cations was investigated using photoluminescent spherical self-assemblies as optical probes. The photoluminescent spherical self-assembly was prepared by the self-organization of a tyrosine-containing bolaamphiphile molecule with a photosensitizer and Tb(3+) ion. The lanthanide ion, Tb(3+), electrically bound to the carboxyl group of the bolaamphiphile molecule, was displaced by alkali and alkaline earth metal cations that had stronger electrophilicity. The PL of the self-assembly decayed remarkably due to the substitution of lanthanide ions with alkali and alkaline earth metal cations. The PL decay showed a positive correlation with cation concentration and was sensitive to the cation valency. Generally, the PL decay was enhanced by the electrophilicity of the cations. However, Ca(2+) showed greater PL decay than Mg(2+) because Ca(2+) could create various complexes with the carboxyl groups of the bolaamphiphile molecule. Microscopic and spectroscopic investigations were conducted to study the photon energy transfer and displacement of Tb(3+) by the cation exchange. This study demonstrated that the PL decay by the displacement of the ionic fluorescent compound was applied to the detection of various cations in aqueous media and is applicable to the development of future optical sensors. Copyright © 2014 Elsevier B.V. All rights reserved.

Bond-length distributions for ions bonded to oxygen: alkali and alkaline-earth metals.

PubMed

Gagné, Olivier Charles; Hawthorne, Frank Christopher

2016-08-01

Bond-length distributions have been examined for 55 configurations of alkali-metal ions and 29 configurations of alkaline-earth-metal ions bonded to oxygen, for 4859 coordination polyhedra and 38 594 bond distances (alkali metals), and for 3038 coordination polyhedra and 24 487 bond distances (alkaline-earth metals). Bond lengths generally show a positively skewed Gaussian distribution that originates from the variation in Born repulsion and Coulomb attraction as a function of interatomic distance. The skewness and kurtosis of these distributions generally decrease with increasing coordination number of the central cation, a result of decreasing Born repulsion with increasing coordination number. We confirm the following minimum coordination numbers: ([3])Li(+), ([3])Na(+), ([4])K(+), ([4])Rb(+), ([6])Cs(+), ([3])Be(2+), ([4])Mg(2+), ([6])Ca(2+), ([6])Sr(2+) and ([6])Ba(2+), but note that some reported examples are the result of extensive dynamic and/or positional short-range disorder and are not ordered arrangements. Some distributions of bond lengths are distinctly multi-modal. This is commonly due to the occurrence of large numbers of structure refinements of a particular structure type in which a particular cation is always present, leading to an over-representation of a specific range of bond lengths. Outliers in the distributions of mean bond lengths are often associated with anomalous values of atomic displacement of the constituent cations and/or anions. For a sample of ([6])Na(+), the ratio Ueq(Na)/Ueq(bonded anions) is partially correlated with 〈([6])Na(+)-O(2-)〉 (R(2) = 0.57), suggesting that the mean bond length is correlated with vibrational/displacement characteristics of the constituent ions for a fixed coordination number. Mean bond lengths also show a weak correlation with bond-length distortion from the mean value in general, although some coordination numbers show the widest variation in mean bond length for zero distortion, e.g. Li(+) in

Behaviour of Rare Earth Elements during the Earth's core formation

NASA Astrophysics Data System (ADS)

Faure, Pierre; Bouhifd, Mohamed Ali; Boyet, Maud; Hammouda, Tahar; Manthilake, Geeth

2017-04-01

Rare Earth Elements (REE) are classified in the refractory group, which means that they have a high temperature condensation and their volatility-controlled fractionation is limited to high-temperature processes. Anomalies have been measured for Eu, Yb and Sm, which are the REE with the lowest condensation temperatures in CAIs and chondrules (e.g. [1]). REE are particularly abundant in the sulfides of enstatite chondrites, 100 to 1000 times the CI value [e.g. 2,3], proving that these elements are not strictly lithophile under extremely reducing conditions. However by investigating experimentally the impact of Earth's core formation on the behavior of Sm and Nd, we have shown the absence of fractionation between Sm and Nd during the segregation of the metallic phase [4]. Recently, Wohlers and Wood [5] proposed that Nd and Sm could be fractionated in presence of a S-rich alloy phase. However, their results were obtained at pressure and temperature conditions below the plausible conditions of the Earth's core formation. Clearly, large pressure range needs to be covered before well-constrained model can be expected. Furthermore, our preliminary metal-silicate partitioning results show that Ce and Eu have higher metal/silicate partition coefficients than their neighboring elements, and that the presence of sulphur enhances the relative difference between partition coefficients. In this presentation, we will present and discuss new metal-silicate partition coefficients of all REE at a deep magma ocean at pressures ranging from those of the uppermost upper mantle ( 5 GPa) to a maximum pressure expected in the range of 20 GPa, temperatures ranging from 2500 to about 3000 K, and oxygen fugacities within IW-1 to IW-5 (1 to 5 orders of magnitude lower than the iron-wüstite buffer). We will discuss the effect of S, as well as the effect of H2O on the behaviour of REE during the Earth's core formation: recent models suggest that contrary to currently accepted beliefs, the

Uncovering the end uses of the rare earth elements.

PubMed

Du, Xiaoyue; Graedel, T E

2013-09-01

The rare earth elements (REE) are a group of fifteen elements with unique properties that make them indispensable for a wide variety of emerging and conventional established technologies. However, quantitative knowledge of REE remains sparse, despite the current heightened interest in future availability of the resources. Mining is heavily concentrated in China, whose monopoly position and potential restriction of exports render primary supply vulnerable to short term disruption. We have drawn upon the published literature and unpublished materials in different languages to derive the first quantitative annual domestic production by end use of individual rare earth elements from 1995 to 2007. The information is illustrated in Sankey diagrams for the years 1995 and 2007. Other years are available in the supporting information. Comparing 1995 and 2007, the production of the rare earth elements in China, Japan, and the US changed dramatically in quantities and structure. The information can provide a solid foundation for industries, academic institutions and governments to make decisions and develop strategies. Copyright © 2013 Elsevier B.V. All rights reserved.

Alkaline earth metal complexes of a phosphine-borane-stabilized carbanion: synthesis, structures, and stabilities.

PubMed

Izod, Keith; Wills, Corinne; Clegg, William; Harrington, Ross W

2007-05-14

The reaction between either MgI2 or CaI2 and 2 equiv of [(Me3Si)2{Me2(H3B)P}C]K (2) in toluene gives the corresponding organo-alkaline earth metal compounds [(Me3Si)2{Me2(H3B)P}C]2M in moderate to good yields [M = Mg (3), Ca (4)]. Compound 3 crystallizes solvent-free, whereas X-ray quality crystals of 4 could not be obtained in the absence of coordinating solvents; crystallization of 4 from cold methylcyclohexane/THF gives the solvate [(Me3Si)2{Me2(H3B)P}C]2Ca(THF)4 (4a). The corresponding heavier alkaline earth metal complexes [(Me3Si)2{Me2(H3B)P}C]2M(THF)5 [M = Sr (7), Ba (8)] are obtained from the reaction between MI2 and 2 equiv of 2 in THF, followed by recrystallization from cold methylcyclohexane/THF. Compound 3 degrades over a period of several weeks at room-temperature both in the solid state and in toluene solution to give the free phosphine-borane (Me3Si)2{Me2(H3B)P}CH (5) as the sole phosphorus-containing product. In addition, compounds 3, 4, and 4a react rapidly with THF in toluene solution, yielding 5 as the sole phosphorus-containing product; in contrast, compounds 7 and 8 are stable toward this solvent.

Theoretical study of the diatomic alkali and alkaline-earth oxides

NASA Technical Reports Server (NTRS)

Langhoff, S. R.; Bauschlicher, C. W., Jr.; Partridge, H.

1986-01-01

Theoretical dissociation energies for the ground states of the alkali and alkaline earth oxides are presented that are believed to be accurate to 0.1 eV. The 2 Pi - 2 Sigma + separations for the alkali oxides are found to be more sensitive to basis set than to electron correlation. Predicted 2 Pi ground states for LiO and NaO and 2 Sigma + ground states for RbO and CsO are found to be in agreement with previous theoretical and experimental work. For KO, a 2 Sigma + state is found at both the numerical Hartree-Fock (NHF) level and at the singles plus doubles configuration interaction level using a Slater basis set that is within 0.02 eV of the NHF limit. It is found that an accurate balanced treatment of the two states requires correlating the electrons on both the metal and oxide ion.

Magnetic Nanofluid Rare Earth Element Extraction Process Report, Techno Economic Analysis, and Results for Geothermal Fluids

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

Pete McGrail

This GDR submission is an interim technical report and raw data files from the first year of testing on functionalized nanoparticles for rare earth element extraction from geothermal fluids. The report contains Rare Earth Element uptake results (percent removal, mg Rare Earth Element/gram of sorbent, distribution coefficient) for the elements of Neodymium, Europium, Yttrium, Dysprosium, and Cesium. A detailed techno economic analysis is also presented in the report for a scaled up geothermal rare earth element extraction process. All rare earth element uptake testing was done on simulated geothermal brines with one rare earth element in each brine. The raremore » earth element uptake testing was conducted at room temperature.« less

Effect of metal cation replacement on the electronic structure of metalorganic halide perovskites: Replacement of lead with alkaline-earth metals

NASA Astrophysics Data System (ADS)

Pazoki, Meysam; Jacobsson, T. Jesper; Hagfeldt, Anders; Boschloo, Gerrit; Edvinsson, Tomas

2016-04-01

Organic and inorganic lead halogen perovskites, and in particular, C H3N H3Pb I3 , have during the last years emerged as a class of highly efficient solar cell materials. Herein we introduce metalorganic halogen perovskite materials for energy-relevant applications based on alkaline-earth metals. Based on the classical notion of Goldschmidt's rules and quantum mechanical considerations, the three alkaline-earth metals, Ca, Sr, and Ba, are shown to be able to exchange lead in the perovskite structure. The three alkaline-earth perovskites, C H3N H3Ca I3,C H3N H3Sr I3 , and C H3N H3Ba I3 , as well as the reference compound, C H3N H3Pb I3 , are in this paper investigated with density functional theory (DFT) calculations, which predict these compounds to exist as stable perovskite materials, and their electronic properties are explored. A detailed analysis of the projected molecular orbital density of states and electronic band structure from DFT calculations were used for interpretation of the band-gap variations in these materials and for estimation of the effective masses of the electrons and holes. Neglecting spin-orbit effects, the band gap of MACa I3,MASr I3 , and MABa I3 were estimated to be 2.95, 3.6, and 3.3 eV, respectively, showing the relative change expected for metal cation exchange. The shifts in the conduction band (CB) edges for the alkaline-earth perovskites were quantified using scalar relativistic DFT calculations and tight-binding analysis, and were compared to the situation in the more extensively studied lead halide perovskite, C H3N H3Pb I3 , where the change in the work function of the metal is the single most important factor in tuning the CB edge and band gap. The results show that alkaline-earth-based organometallic perovskites will not work as an efficient light absorber in photovoltaic applications but instead could be applicable as charge-selective contact materials. The rather high CB edge and the wide band gap together with the large

Chemical composition of modern and fossil Hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation - Part 2: Alkaline earth elements as tracers of watershed hydrochemistry and provenance

NASA Astrophysics Data System (ADS)

Brügmann, G.; Krause, J.; Brachert, T. C.; Stoll, B.; Weis, U.; Kullmer, O.; Ssemmanda, I.; Mertz, D. F.

2012-03-01

For reconstructing environmental change in terrestrial realms the geochemistry of fossil bioapatite in bones and teeth is among the most promising applications. This study demonstrates that alkaline earth elements in enamel of Hippopotamids, in particular Ba and Sr are tracers for water provenance and hydrochemistry. The studied specimens are molar teeth from Hippopotamids found in modern and fossil lacustrine settings of the Western Branch of the East African Rift system (Lake Kikorongo, Lake Albert, and Lake Malawi) and from modern fluvial environments of the Nile River. Concentrations in enamel vary by ca. two orders of magnitude for Ba (120-9336 μg g-1) as well as for Sr (9-2150 μg g-1). Concentration variations in enamel are partly induced during post-mortem alteration and during amelogenesis, but the major contribution originates from the variable water chemistry in the habitats of the Hippopotamids which is dominated by the lithologies and weathering processes in the watershed areas. Amelogenesis causes a distinct distribution of Ba and Sr in modern and fossil enamel, in that element concentrations increase along profiles from the outer rim towards the enamel-dentin junction by a factor of 1.3-1.5. These elements are well correlated with MgO and Na2O in single specimens, thus suggesting that their distribution is determined by a common, single process. Presuming that the shape of the tooth is established at the end of the secretion process and apatite composition is in equilibrium with the enamel fluid, the maturation process can be modeled by closed system Rayleigh crystallization. Enamel from many Hippopotamid specimens has Sr/Ca and Ba/Ca which are typical for herbivores, but the compositions extend well into the levels of plants and carnivores. Within enamel from single specimens these element ratios covary and provide a specific fingerprint of the Hippopotamid habitat. All specimens together, however, define subparallel trends with different Ba

STABILIZATION OF SPIDER CRAB NERVE MEMBRANES BY ALKALINE EARTHS, AS MANIFESTED IN RESTING POTENTIAL MEASUREMENTS

PubMed Central

Guttman, Rita

1940-01-01

1. The alkaline earths, Ba, Sr, Ca, and Mg, in isotonic solutions of their chlorides, have, in general, no effect upon the resting potential of non-medullated spider crab nerve. 2. Ba, Sr, and Ca can, however, prevent the depressing action of K upon the resting potential. The order of effectiveness of these ions in this regard is the following: Ba > Sr > Ca. 3. Ba, Sr, Ca, and Mg oppose the depressing action of veratrine sulfate upon the resting potential. The order of effectiveness is Ba > Sr > Ca > Mg. The relation between drop in potential caused by veratrine sulfate and the logarithm of the veratrine sulfate concentration is a linear one. 4. The action of various other organic ions and molecules which depress the resting potential: saponin, amyl urethane, chloral hydrate, and Na salicylate is neutralized by Ba. 5. Hypertonic sea water solutions do not affect the resting potential. Also, preliminary experiments indicate that the nerves do not shrink in hypertonic solutions although they swell in hypotonic sea water. 6. The alkaline earths depress excitability reversibly. The various organic agents which depress the resting potential also depress excitability, in most cases, reversibly, but the concentrations necessary to depress excitability are much smaller than those necessary to depress the resting potential. 7. The relation of these findings to theories put forward as possible explanations of resting potential phenomena is considered. PMID:19873160

Health risk assessment of rare earth elements in cereals from mining area in Shandong, China.

PubMed

Zhuang, Maoqiang; Wang, Liansen; Wu, Guangjian; Wang, Kebo; Jiang, Xiaofeng; Liu, Taibin; Xiao, Peirui; Yu, Lianlong; Jiang, Ying; Song, Jian; Zhang, Junli; Zhou, Jingyang; Zhao, Jinshan; Chu, Zunhua

2017-08-29

To investigate the concentrations of rare earth elements in cereals and assess human health risk through cereal consumption, a total of 327 cereal samples were collected from rare earth mining area and control area in Shandong, China. The contents of 14 rare earth elements were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The medians of total rare earth elements in cereals from mining and control areas were 74.22 μg/kg and 47.83 μg/kg, respectively, and the difference was statistically significant (P < 0.05). The wheat had the highest rare earth elements concentrations (109.39 μg/kg and 77.96 μg/kg for mining and control areas, respectively) and maize had the lowest rare earth elements concentrations (42.88 μg/kg and 30.25 μg/kg for mining and control areas, respectively). The rare earth elements distribution patterns for both areas were characterized by enrichment of light rare earth elements. The health risk assessment demonstrated that the estimated daily intakes of rare earth elements through cereal consumption were considerably lower than the acceptable daily intake (70 μg/kg bw). The damage to adults can be neglected, but more attention should be paid to the effects of continuous exposure to rare earth elements on children.

[Physiological effects of rare earth elements and their application in traditional Chinese medicine].

PubMed

Zhou, Jie; Guo, Lanping; Xiao, Wenjuan; Geng, Yanling; Wang, Xiao; Shi, Xin'gang; Dan, Staerk

2012-08-01

The process in the studies on physiological effects of rare earth elements in plants and their action mechanisms were summarized in the aspects of seed germination, photosynthesis, mineral metabolism and stress resistance. And the applications of rare earth elements in traditional Chinese medicine (TCM) in recent years were also overviewed, which will provide reference for further development and application of rare earth elements in TCM.

Anthropogenic Cycles of Rare Earth Elements

NASA Astrophysics Data System (ADS)

Du, X.; Graedel, T. E.

2009-12-01

This research will develop quantitatively resolved anthropogenic cycles and in-use stocks for the rare earth metals specifically cerium, lanthanum and dysprosium in Japan, China, and the U.S. for the year of 2007. Rare earth elements (REE) is a group of 17 scare metals widely used in a growing number of emerging technologies and have been in high demand for emerging technologies as raw materials during past the three decades. New market participants from newly industrializing countries, primarily China, have had strong impacts on the demand of share. Consequently, the importance to sustain a reliable, steady, uninterrupted supply on global market triggered comprehensive research to recognize and understand the life cycles of rare earths. Moreover, because China plays a dominant role in mining production since 1990, it requires the assessment for the countries, which are almost completely dependent on imports from China with respect to rare earth resources. The study aims to analyze the flows and stocks of rare earth elements individually as elemental form in spite of their natural geological co-occurrence and mixed composition in applications. By applying the method of Material Flow Analysis (MFA) work has been done on evaluating current and historical flows of specific technologically significant materials, for example, copper, zinc, nickel, etc., determining the stocks available in different types of reservoirs (e.g., lithosphere, in-use) and the flows among the reservoirs, developing scenarios of possible futures of metal use, and assessing the environmental and policy implications of the results. Therefore, REE as a new target deserves inclusion because of its potential demand-supply conflict and importance to secure the competitive advantage of technical innovation in future. This work will generate a quantitatively resolved anthropogenic life cycle and in-use stocks for REE for the main target countries for a chosen year, 2007, providing flows and stocks from

Multi-objective optimization of chromatographic rare earth element separation.

PubMed

Knutson, Hans-Kristian; Holmqvist, Anders; Nilsson, Bernt

2015-10-16

The importance of rare earth elements in modern technological industry grows, and as a result the interest for developing separation processes increases. This work is a part of developing chromatography as a rare earth element processing method. Process optimization is an important step in process development, and there are several competing objectives that need to be considered in a chromatographic separation process. Most studies are limited to evaluating the two competing objectives productivity and yield, and studies of scenarios with tri-objective optimizations are scarce. Tri-objective optimizations are much needed when evaluating the chromatographic separation of rare earth elements due to the importance of product pool concentration along with productivity and yield as process objectives. In this work, a multi-objective optimization strategy considering productivity, yield and pool concentration is proposed. This was carried out in the frame of a model based optimization study on a batch chromatography separation of the rare earth elements samarium, europium and gadolinium. The findings from the multi-objective optimization were used to provide with a general strategy for achieving desirable operation points, resulting in a productivity ranging between 0.61 and 0.75 kgEu/mcolumn(3), h(-1) and a pool concentration between 0.52 and 0.79 kgEu/m(3), while maintaining a purity above 99% and never falling below an 80% yield for the main target component europium. Copyright © 2015 Elsevier B.V. All rights reserved.

UV-active plasmons in alkali and alkaline-earth intercalated graphene

NASA Astrophysics Data System (ADS)

Despoja, V.; Marušić, L.

2018-05-01

The interband π and π +σ plasmons in pristine graphene and the Dirac plasmon in doped graphene are not applicable, since they are broad or weak, and weakly couple to an external longitudinal or electromagnetic probe. Therefore, the ab initio density functional theory is used to demonstrate that the chemical doping of the graphene by the alkali or alkaline-earth atoms dramatically changes the poor graphene excitation spectrum in the ultraviolet frequency range (4-10 eV). Four prominent modes are detected. Two of them are the intralayer plasmons with square-root dispersion, characteristic of the two-dimensional modes. The remaining two are the interlayer plasmons, very strong in the long-wavelength limit but damped for larger wave vectors. The optical absorption calculations show that the interlayer plasmons are both optically active, which makes these materials suitable for small-organic-molecule sensing. This is particularly intriguing because the optically active two-dimensional plasmons have not been detected in other materials.

Impacts of artificial ocean alkalinization on the carbon cycle and climate in Earth system simulations

NASA Astrophysics Data System (ADS)

González, Miriam Ferrer; Ilyina, Tatiana

2016-06-01

Using the state-of-the-art emissions-driven Max Planck Institute Earth system model, we explore the impacts of artificial ocean alkalinization (AOA) with a scenario based on the Representative Concentration Pathway (RCP) framework. Addition of 114 Pmol of alkalinity to the surface ocean stabilizes atmospheric CO2 concentration to RCP4.5 levels under RCP8.5 emissions. This scenario removes 940 GtC from the atmosphere and mitigates 1.5 K of global warming within this century. The climate adjusts to the lower CO2 concentration preventing the loss of sea ice and high sea level rise. Seawater pH and the carbonate saturation state (Ω) rise substantially above levels of the current decade. Pronounced differences in regional sensitivities to AOA are projected, with the Arctic Ocean and tropical oceans emerging as hot spots for biogeochemical changes induced by AOA. Thus, the CO2 mitigation potential of AOA comes at a price of an unprecedented ocean biogeochemistry perturbation with unknown ecological consequences.

Coal fly ash as a resource for rare earth elements.

PubMed

Franus, Wojciech; Wiatros-Motyka, Małgorzata M; Wdowin, Magdalena

2015-06-01

Rare earth elements (REE) have been recognised as critical raw materials, crucial for many clean technologies. As the gap between their global demand and supply increases, the search for their alternative resources becomes more and more important, especially for the countries which depend highly on their import. Coal fly ash (CFA), which when not utilised is considered waste, has been regarded as the possible source of many elements, including REE. Due to the increase in the energy demand, CFA production is expected to grow, making research into the use of this material a necessity. As Poland is the second biggest coal consumer in the European Union, the authors have studied different coal fly ashes from ten Polish power plants for their rare earth element content. All the fly ashes have a broadly similar distribution of rear earth elements, with light REE being dominant. Most of the samples have REE content relatively high and according to Seredin and Dai (Int J Coal Geol 94: 67-93, 2012) classification can be considered promising REE raw materials.

Boson peak of alkali and alkaline earth silicate glasses: influence of the nature and size of the network-modifying cation.

PubMed

Richet, Nicolas F

2012-01-21

The influence of the size of the alkaline earth cation on the boson peak of binary metasilicate glasses, MSiO(3) (M = Mg, Ca, Sr, Ba), has been investigated from vibrational densities of states determined by inversion of low-temperature heat capacities. As given both by C(p)/T(3) and g(ω)/ω(2), the intensity of the boson peak undergoes a 7-fold increase from Mg to Ba, whereas its temperature and frequency correlatively decrease from 18 to 10 K and from 100 to 20 cm(-1), respectively. The boson peak results from a combination of librations of SiO(4) tetrahedra and localized vibrations of network-modifying cations with non-bridging oxygens whose contribution increases markedly with the ionic radius of the alkaline earth. As a function of ionic radii, the intensity for Sr and Ba varies in the same way as previously found for alkali metasilicate glasses. The localized vibrations involving alkali and heavy alkaline earth cations appear to be insensitive to the overall glass structure. Although the new data are coherent with an almost linear relationship between the temperature of the boson peak and transverse sound velocity, pure SiO(2) and SiO(2)-rich glasses make marked exceptions to this trend because of the weak transverse character of SiO(4) librations. Finally, the universality of the calorimetric boson peak is again borne out because all data for silicate glasses collapse on the same master curve when plotted in a reduced form (C(P)∕/T(3))/(C(P)/T(3))(b) vs. T/T(b). © 2012 American Institute of Physics

U.S. trade dispute with China over rare earth elements

NASA Astrophysics Data System (ADS)

Showstack, Randy

2012-03-01

The U.S. government has brought a new trade case against China over rare earth elements (REE) as well as tungsten and molybdenum, President Barack Obama announced on 13 March. Japan and the European Union also have taken similar actions against China about REEs, which are a group of 17 chemically similar metallic elements that are used in a variety of electronic, optical, magnetic, and catalytic applications. REEs are plentiful in the Earth's crust, although China currently has about 37% of the world's reserves and accounts for more than 95% of the world's production of the elements, according to the British Geological Survey. The United States has requested consultations with China at the World Trade Organization (WTO) concerning "China's unfair export restraints on rare earths, as well as tungsten and molybdenum," the Office of the United States Trade Representative announced in a 13 March statement.

Two main and a new type rare earth elements in Mg alloys: A review

NASA Astrophysics Data System (ADS)

Kong, Linghang

2017-09-01

Magnesium (Mg) alloys stand for the lightest structure engineering materials. Moreover, the strengthening of Mg alloys in ductility, toughness and corrosion predominates their wide applications. With adding rare earth elements in Mg, the mechanical properties will be improved remarkably, especially their plasticity and strength. A brief overview of the addition of rare earth elements for Mg alloys is shown. The basic mechanisms of strengthening Mg alloys with rare earth elements are reviewed, including the solid solution strengthening, grain refinement and long period stacking ordered (LPSO) phase. Furthermore, the available rare earth elements are summarized by type, chemical or physical effects and other unique properties. Finally, some challenge problems that the research is facing and future expectations of ra-re-earth Mg alloys are stated and discussed.

Catalytic Graphitization of Coal-Based Carbon Materials with Light Rare Earth Elements.

PubMed

Wang, Rongyan; Lu, Guimin; Qiao, Wenming; Yu, Jianguo

2016-08-30

The catalytic graphitization mechanism of coal-based carbon materials with light rare earth elements was investigated using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, selected-area electron diffraction, and high-resolution transmission electron microscopy. The interface between light rare earth elements and carbon materials was carefully observed, and two routes of rare earth elements catalyzing the carbon materials were found: dissolution-precipitation and carbide formation-decomposition. These two simultaneous processes certainly accelerate the catalytic graphitization of carbon materials, and light rare earth elements exert significant influence on the microstructure and thermal conductivity of graphite. Moreover, by virtue of praseodymium (Pr), it was found that a highly crystallographic orientation of graphite was induced and formed, which was reasonably attributed to the similar arrangements of the planes perpendicular to (001) in both graphite and Pr crystals. The interface between Pr and carbon was found to be an important factor for the orientation of graphite structure.

Leaching behavior of rare earth elements in Fort Union lignite coals of North America

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

Laudal, Daniel A.; Benson, Steven A.; Addleman, Raymond Shane

Rare earth elements are crucial materials in an incredible array of consumer goods, energy system components and military defense applications. However, the global production and entire value chain for rare earth elements is dominated by China, with the U.S. currently 100% import reliant for these critical materials. Traditional mineral ores including those previously mined in the U.S., however, have several challenges. Chief among these is that the content of the most critical and valuable of the rare earths are deficient, making mining uneconomical. Further, the supply of these most critical rare earths is nearly 100% produced in China from amore » single resource that is only projected to last another 10 to 20 years. The U.S. currently considers the rare earths market an issue of national security. It is imperative that alternative domestic sources of rare earths be identified and methods developed to produce them. Recently, coal and coal byproducts have been identified as one of these promising alternative resources. This paper details the results of a study on characterization of North Dakota lignite and lignite-related feedstocks as an assessment of their feasibility for rare earth element recovery. The abundance, distribution and modes of occurrence of the rare earth elements in the samples collected were determined in this initial study to inform the selection of appropriate extraction and concentration methods to recover the rare earth elements. Materials investigated include the lignite coals, clay-rich sediments associated with the coal seams, and materials associated with a lignite beneficiation system and power plant. The results show that high rare earth element levels exist both in lignite coals and associated sediments. The form of the rare earth elements in the clay materials is primarily as ultra-fine mineral grains. In the lignite coals, approximately 80-95% of the rare earths content is organically associated, primarily as coordination

Fluorescent probes and bioimaging: alkali metals, alkaline earth metals and pH.

PubMed

Yin, Jun; Hu, Ying; Yoon, Juyoung

2015-07-21

All living species and life forms have an absolute requirement for bio-functional metals and acid-base equilibrium chemistry owing to the critical roles they play in biological processes. Hence, a great need exists for efficient methods to detect and monitor biometals and acids. In the last few years, great attention has been paid to the development of organic molecule based fluorescent chemosensors. The availability of new synthetic fluorescent probes has made fluorescence microscopy an indispensable tool for tracing biologically important molecules and in the area of clinical diagnostics. This review highlights the recent advances that have been made in the design and bioimaging applications of fluorescent probes for alkali metals and alkaline earth metal cations, including lithium, sodium and potassium, magnesium and calcium, and for pH determination within biological systems.

Modifying the size and uniformity of upconversion Yb/Er:NaGdF4 nanocrystals through alkaline-earth doping.

PubMed

Lei, Lei; Chen, Daqin; Huang, Ping; Xu, Ju; Zhang, Rui; Wang, Yuansheng

2013-11-21

NaGdF4 is regarded as an ideal upconversion (UC) host material for lanthanide (Ln(3+)) activators because of its unique crystal structure, high Ln(3+) solubility, low phonon energy and high photochemical stability, and Ln(3+)-doped NaGdF4 UC nanocrystals (NCs) have been widely investigated as bio-imaging and magnetic resonance imaging agents recently. To realize their practical applications, controlling the size and uniformity of the monodisperse Ln(3+)-doped NaGdF4 UC NCs is highly desired. Unlike the routine routes by finely adjusting the multiple experimental parameters, herein we provide a facile and straightforward strategy to modify the size and uniformity of NaGdF4 NCs via alkaline-earth doping for the first time. With the increase of alkaline-earth doping content, the size of NaGdF4 NCs increases gradually, while the size-uniformity is still retained. We attribute this "focusing" of size distribution to the diffusion controlled growth of NaGdF4 NCs induced by alkaline-earth doping. Importantly, adopting the Ca(2+)-doped Yb/Er:NaGdF4 NCs as cores, the complete Ca/Yb/Er:NaGdF4@NaYF4 core-shell particles with excellent size-uniformity can be easily achieved. However, when taking the Yb/Er:NaGdF4 NCs without Ca(2+) doping as cores, they could not be perfectly covered by NaYF4 shells, and the obtained products are non-uniform in size. As a result, the UC emission intensity of the complete core-shell NCs increases by about 30 times in comparison with that of the cores, owing to the effective surface passivation of the Ca(2+)-doped cores and therefore protection of Er(3+) in the cores from the non-radiative decay caused by surface defects, whereas the UC intensity of the incomplete core-shell NCs is enhanced by only 3 times.

The elements of the Earth's magnetism and their secular changes between 1550 and 1915

NASA Technical Reports Server (NTRS)

Fritsche, H.

1983-01-01

The results of an investigation about the magnetic agents outside the Earth's surface as well as the Earth's magnetic elements for the epochs 1550, 1900, 1915 are presented. The secular changes of the Earth's magnetic elements during the time interval 1550 - 1900 are also included.

Rare Earth Element Geochemistry for Produced Waters, WY

DOE Data Explorer

Quillinan, Scott; Nye, Charles; McLing, Travis; Neupane, Hari

2016-06-30

These data represent major, minor, trace, isotopes, and rare earth element concentrations in geologic formations and water associated with oil and gas production. *Note - Link below contains updated version of spreadsheet (6/14/2017)

Rare earths and other trace elements in Luna 16 soil.

NASA Technical Reports Server (NTRS)

Helmke, P. A.; Haskin, L. A.

1972-01-01

An analysis has been made of four small samples of material brought to earth by the Luna 16 mission, with the aim to determine rare earths and other trace elements in these samples. The analytical results are tabulated, and the rare earth abundances are compared with the average for chondrites. A comparison is also made with the results of similar analyses of Apollo samples.

Design of ternary alkaline-earth metal Sn(II) oxides with potential good p-type conductivity

DOE PAGES

Du, Mao -Hua; Singh, David J.; Zhang, Lijun; ...

2016-04-19

Oxides with good p-type conductivity have been long sought after to achieve high performance all-oxide optoelectronic devices. Divalent Sn(II) based oxides are promising candidates because of their rather dispersive upper valence bands caused by the Sn-5s/O-2p anti-bonding hybridization. There are so far few known Sn(II) oxides being p-type conductive suitable for device applications. Here, we present via first-principles global optimization structure searches a material design study for a hitherto unexplored Sn(II)-based system, ternary alkaline-earth metal Sn(II) oxides in the stoichiometry of MSn 2O 3 (M = Mg, Ca, Sr, Ba). We identify two stable compounds of SrSn 2O 3 andmore » BaSn 2O 3, which can be stabilized by Sn-rich conditions in phase stability diagrams. Their structures follow the Zintl behaviour and consist of basic structural motifs of SnO 3 tetrahedra. Unexpectedly they show distinct electronic properties with band gaps ranging from 1.90 (BaSn 2O 3) to 3.15 (SrSn 2O 3) eV, and hole effective masses ranging from 0.87 (BaSn 2O 3) to above 6.0 (SrSn 2O 3) m0. Further exploration of metastable phases indicates a wide tunability of electronic properties controlled by the details of the bonding between the basic structural motifs. Lastly, this suggests further exploration of alkaline-earth metal Sn(II) oxides for potential applications requiring good p-type conductivity such as transparent conductors and photovoltaic absorbers.« less

Review of rare earth element concentrations in oil shales of the Eocene Green River Formation

USGS Publications Warehouse

Birdwell, Justin E.

2012-01-01

Concentrations of the lanthanide series or rare earth elements and yttrium were determined for lacustrine oil shale samples from the Eocene Green River Formation in the Piceance Basin of Colorado and the Uinta Basin of Utah. Unprocessed oil shale, post-pyrolysis (spent) shale, and leached shale samples were examined to determine if oil-shale processing to generate oil or the remediation of retorted shale affects rare earth element concentrations. Results for unprocessed Green River oil shale samples were compared to data published in the literature on reference materials, such as chondritic meteorites, the North American shale composite, marine oil shale samples from two sites in northern Tibet, and mined rare earth element ores from the United States and China. The Green River oil shales had lower rare earth element concentrations (66.3 to 141.3 micrograms per gram, μg g-1) than are typical of material in the upper crust (approximately 170 μg g-1) and were also lower in rare earth elements relative to the North American shale composite (approximately 165 μg g-1). Adjusting for dilution of rare earth elements by organic matter does not account for the total difference between the oil shales and other crustal rocks. Europium anomalies for Green River oil shales from the Piceance Basin were slightly lower than those reported for the North American shale composite and upper crust. When compared to ores currently mined for rare earth elements, the concentrations in Green River oil shales are several orders of magnitude lower. Retorting Green River oil shales led to a slight enrichment of rare earth elements due to removal of organic matter. When concentrations in spent and leached samples were normalized to an original rock basis, concentrations were comparable to those of the raw shale, indicating that rare earth elements are conserved in processed oil shales.

[Spectroscopic Research on Slag Nanocrystal Glass Ceramics Containing Rare Earth Elements].

PubMed

Ouyang, Shun-li; Li, Bao-wei; Zhang, Xue-feng; Jia, Xiao-lin; Zhao, Ming; Deng, Lei-bo

2015-08-01

The research group prepared the high-performance slag nanocrystal glass ceramics by utilizing the valuable elements of the wastes in the Chinese Bayan Obo which are characterized by their symbiotic or associated existence. In this paper, inductively coupled plasma emission spectroscopy (ICP), X-ray diffraction (XRD), Raman spectroscopy (Raman) and scanning electron microscopy (SEM) are all used in the depth analysis for the composition and structure of the samples. The experiment results of ICP, XRD and SEM showed that the principal crystalline phase of the slag nanocrystal glass ceramics containing rare earth elements is diopside, its grain size ranges from 45 to 100 nm, the elements showed in the SEM scan are basically in consistent with the component analysis of ICP. Raman analysis indicated that its amorphous phase is a three-dimensional network structure composed by the structural unit of silicon-oxy tetrahedron with different non-bridging oxygen bonds. According to the further analysis, we found that the rare earth microelement has significant effect on the network structure. Compared the nanocrystal slag glass ceramic with the glass ceramics of similar ingredients, we found that generally, the Raman band wavenumber for the former is lower than the later. The composition difference between the glass ceramics and the slag nanocrystal with the similar ingredients mainly lies on the rare earth elements and other trace elements. Therefore, we think that the rare earth elements and other trace elements remains in the slag nanocrystal glass ceramics have a significant effect on the network structure of amorphous phase. The research method of this study provides an approach for the relationship among the composition, structure and performance of the glass ceramics.

Evaluation of Rare Earth Element Extraction from North Dakota Coal-Related Feed Stocks

NASA Astrophysics Data System (ADS)

Laudal, Daniel A.

The rare earth elements consist of the lanthanide series of elements with atomic numbers from 57-71 and also include yttrium and scandium. Due to their unique properties, rare earth elements are crucial materials in an incredible array of consumer goods, energy system components and military defense applications. However, the global production and entire value chain for rare earth elements is dominated by China, with the U.S. currently 100% import reliant for these critical materials. Traditional mineral ores including previously mined deposits in the U.S., however, have several challenges. Chief among these is that the content of the most critical and valuable of the rare earths are deficient, making mining uneconomical. Further, the supply of these most critical rare earths is nearly 100% produced in China from a single resource that is only projected to last another 10 to 20 years. The U.S. currently considers the rare earths market an issue of national security. It is imperative that alternative domestic sources of rare earths be identified and methods developed to produce them. Recently, coal and coal byproducts have been identified as one of these promising alternative resources. This dissertation details a study on evaluation of the technical and economic feasibility of rare earth element recovery from North Dakota lignite coal and lignite-related feedstocks. There were four major goals of this study: i) identify lignite or lignite-related feedstocks with total rare earth element content above 300 parts per million, a threshold dictated by the agency who funded this research as the minimum for economic viability, ii) determine the geochemistry of the feedstocks and understand the forms and modes of occurrence of the rare earth elements, information necessary to inform the development of extraction and concentration methods, iii) identify processing methods to concentrate the rare earth elements from the feedstocks to a target of two weight percent, a value

Extraction of rare earth elements from low-grade Bauxite via precipitation reaction

NASA Astrophysics Data System (ADS)

Kusrini, E.; Nurani, Y.; Bahari, ZJ

2018-03-01

The aim of this research was to determine the optimum hydrometallurgical parameters to extract the rare earth elements (REE) from low-grade bauxite through acid leaching and precipitation reaction. REE or lanthanide recovery by a precipitation method with sodium sulphate and sodium phosphate as precipitation agents is reported where the effect of pH and recovery of REE are described. The metal composition of REE in low-grade bauxite after treatment were analyzed by ICP-OES. The total recovery values of REE elements at the first precipitation reaction using sodium sulphate as the precipitation agent at pH 3.5 showed ~68.2% of lanthanum, ~18.9% cerium, and ~7.8% yttrium. Lanthanum was the rare-earth element present at the highest concentration in the low-grade bauxite after the series treatments. An optimum pH of 3.5 for precipitation of rare-earth elements using sodium sulphate was demonstrated where this method is recommended for the extraction of REE elements from low-grade bauxite.

REDISTRIBUTION OF ALKALINE ELEMENTS IN ASSOCIATION WITH AQUEOUS ACTIVITY IN THE EARLY SOLAR SYSTEM

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

Hidaka, Hiroshi; Higuchi, Takuya; Yoneda, Shigekazu, E-mail: hidaka@hiroshima-u.ac.jp, E-mail: s-yoneda@kahaku.go.jp

2015-12-10

It is known that the Sayama meteorite (CM2) shows an extensive signature for aqueous alteration on the meteorite parent body, and that most of the primary minerals in the chondrules are replaced with phyllosilicates as the result of the aqueous alteration. In this paper, it is confirmed from the observation of two-dimensional Raman spectra that a part of olivine in a chondrule collected from the Sayama chondrite is serperntinized. Ion microprobe analysis of the chondrule showed that alkaline elements such as Rb and Cs are heterogeneously redistributed in the chondrule. The result of higher Rb and Cs contents in serpentinizedmore » phases in the chondrule rather than in other parts suggested the selective adsorption of alkaline elements into the serpentine in association with early aqueous activity on the meteorite parent body. Furthermore Ba isotopic analysis provided variations of {sup 135}Ba/{sup 138}Ba and {sup 137}Ba/{sup 138}Ba in the chondrule. This result was consistent with our previous isotopic data suggesting isotopic evidence for the existence of the presently extinct nuclide {sup 135}Cs in the Sayama meteorite, but the abundance of {sup 135}Cs in the solar system remains unclear because of large analytical uncertainties.« less

Chemical composition of modern and fossil hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation - Part 2: Alkaline earth elements as tracers of watershed hydrochemistry and provenance

NASA Astrophysics Data System (ADS)

Brügmann, G.; Krause, J.; Brachert, T. C.; Stoll, B.; Weis, U.; Kullmer, O.; Ssemmanda, I.; Mertz, D. F.

2012-11-01

This study demonstrates that alkaline earth elements in enamel of hippopotamids, in particular Ba and Sr, are tracers for water provenance and hydrochemistry in terrestrial settings. The studied specimens are permanent premolar and molar teeth found in modern and fossil lacustrine sediments of the Western Branch of the East African Rift system (Lake Kikorongo, Lake Albert, and Lake Malawi) and from modern fluvial environments of the Nile River. Concentrations in enamel vary by two orders of magnitude for Ba (120-9336 μg g-1) as well as for Sr (9-2150 μg g-1). The variations are partially induced during post-mortem alteration and during amelogenesis, but the major contribution originates ultimately from the variable water chemistry in the habitats of the hippopotamids which is controlled by the lithologies and weathering processes in the watershed areas. Amelogenesis causes a distinct distribution of MgO, Ba and Sr in modern and fossil enamel, in that element concentrations increase along profiles from the outer rim towards the enamel-dentin junction by a factor of 1.3-1.9. These elements are well correlated in single specimens, thus suggesting that their distribution is determined by a common, single process, which can be described by closed system Rayleigh crystallization of bioapatite in vivo. Enamel from most hippopotamid specimens has Sr/Ca and Ba/Ca which are typical for herbivores. However, Ba/Sr ranges from 0.1 to 3 and varies on spatial and temporal scales. Thus, Sr concentrations and Ba/Sr in enamel differentiate between habitats having basaltic mantle rocks or Archean crustal rocks as the ultimate sources of Sr and Ba. This provenance signal is modulated by climate change. In Miocene to Pleistocene enamel from the Lake Albert region, Ba/Sr decreases systematically with time from 2 to 0.5. This trend can be correlated with changes in climate from humid to arid, in vegetation from C3 to C4 biomass as well as with increasing evaporation of the lake water

Evaluation of AA5052 alloy anode in alkaline electrolyte with organic rare-earth complex additives for aluminium-air batteries

NASA Astrophysics Data System (ADS)

Wang, Dapeng; Li, Heshun; Liu, Jie; Zhang, Daquan; Gao, Lixin; Tong, Lin

2015-10-01

Behaviours of the AA5052 aluminium alloy anode of the alkaline aluminium-air battery are studied by the hydrogen evolution test, the electrochemical measurements and the surface analysis method. The combination of amino-acid and rare earth as electrolyte additives effectively retards the self-corrosion of AA5052 aluminium alloy in 4 M NaOH solution. It shows that the combination of L-cysteine and cerium nitrate has a synergistic effect owing to the formation of a complex film on AA5052 alloy surface. The organic rare-earth complex can decrease the anodic polarisation, suppress the hydrogen evolution and increase the anodic utilization rate.

Deep-sea mud in the Pacific Ocean as a potential resource for rare-earth elements

NASA Astrophysics Data System (ADS)

Kato, Yasuhiro; Fujinaga, Koichiro; Nakamura, Kentaro; Takaya, Yutaro; Kitamura, Kenichi; Ohta, Junichiro; Toda, Ryuichi; Nakashima, Takuya; Iwamori, Hikaru

2011-08-01

World demand for rare-earth elements and the metal yttrium--which are crucial for novel electronic equipment and green-energy technologies--is increasing rapidly. Several types of seafloor sediment harbour high concentrations of these elements. However, seafloor sediments have not been regarded as a rare-earth element and yttrium resource, because data on the spatial distribution of these deposits are insufficient. Here, we report measurements of the elemental composition of over 2,000 seafloor sediments, sampled at depth intervals of around one metre, at 78 sites that cover a large part of the Pacific Ocean. We show that deep-sea mud contains high concentrations of rare-earth elements and yttrium at numerous sites throughout the eastern South and central North Pacific. We estimate that an area of just one square kilometre, surrounding one of the sampling sites, could provide one-fifth of the current annual world consumption of these elements. Uptake of rare-earth elements and yttrium by mineral phases such as hydrothermal iron-oxyhydroxides and phillipsite seems to be responsible for their high concentration. We show that rare-earth elements and yttrium are readily recovered from the mud by simple acid leaching, and suggest that deep-sea mud constitutes a highly promising huge resource for these elements.

Rare Earth and other Chemical Elements Accumulation in Vines of Fogo Island (Cape Verde)

NASA Astrophysics Data System (ADS)

Marques, Rosa; Prudêncio, Maria Isabel; Rocha, Fernando; Dias, Maria Isabel; Franco, Dulce

2017-04-01

The Fogo Island is the fourth bigger island of the Cape Verde (central Atlantic Ocean). This archipelago is located 570 kilometres off the coast of West Africa, and is characterized by a semi-arid climate. The volcanic soils of the caldera of this island, with an active volcanism during historical times, have been used for viticulture. The study of uptake of chemical elements by vines - absorption and translocation to grapes - grown in soils developed on alkaline pyroclasts is the main goal of this work. The concentrations of 27 chemical elements in bark, leafs and grapes of two vines, as well as in the corresponding soils (< 2 mm) were determined by instrumental neutron activation analysis. Irradiations of milled samples and standards were made in the core grid of the Portuguese Research Reactor (CTN/IST, Bobadela). The distribution patterns of the enrichment factors (EF) in the different parts of the plants are similar for the two sampling sites. Significant EF were found for the majority of the chemical elements studied, in the several parts of the plants, particularly in grapes where Cr, As, Sb and U are accumulated (EF > 50). The bioavailable fraction of Cr and As in these soils may be due to the low percentage of iron oxides (particularly in the form of nanoparticles), which play an important role in the retention of these elements. The factors responsible for the phytoavailability of Sb in soils and its uptake by plants it's still poorly known. Although the Sb concentrations in earth's crust are low, higher concentrations of this element in soils may be related with hydrothermal and volcanic processes. Also, the temperature may influence the accumulation of Sb in plants, with an increase of the Sb uptake by plants at higher temperatures, due to an increased desorption rate of Sb from soil particles. Concerning U, its mobility and dispersion in soils is controlled by its oxidation state, its adsorption capacity in clay minerals or iron oxides, and the ability

Addressing Rare-Earth Element Criticality: An Example from the Aviation Industry

NASA Astrophysics Data System (ADS)

Ku, Anthony Y.; Dosch, Christopher; Grossman, Theodore R.; Herzog, Joseph L.; Maricocchi, Antonio F.; Polli, Drew; Lipkin, Don M.

2014-11-01

Rare-earth (RE) elements are enablers for a wide range of technologies, including high-strength permanent magnets, energy-efficient lighting, high-temperature thermal barrier coatings, and catalysts. While direct material substitution is difficult in many of these applications because of the specific electronic, optical, or electrochemical properties imparted by the individual rare-earth elements, we describe an example from the aviation industry where supply chain optimization may be an option. Ceramic matrix composite engine components require environmental barrier coatings (EBCs) to protect them from extreme temperatures and adverse reactions with water vapor in the hot gas path. EBC systems based on rare-earth silicates offer a unique combination of environmental resistance, thermal expansion matching, thermal conductivity, and thermal stability across the service temperature window. Several pure rare-earth silicates and solid solutions have been demonstrated in EBC applications. However, all rely on heavy rare-earth elements (HREEs) for phase stability. This article considers the possibility of using separation tailings containing a mixture of HREEs as a source material in lieu of using the high-purity HREE oxides. This option arises because the desired properties of RE-silicate EBCs derive from the average cation size rather than the electronic properties of the individual rare-earth cations. Because separation tailings have not incurred the costs associated with the final stages of separation, they offer an economical alternative to high-purity oxides for this emerging application.

Electro-kinetic Separation of Rare Earth Elements Using a Redox-Active Ligand.

PubMed

Fang, Huayi; Cole, Bren E; Qiao, Yusen; Bogart, Justin A; Cheisson, Thibault; Manor, Brian C; Carroll, Patrick J; Schelter, Eric J

2017-10-16

Purification of rare earth elements is challenging due to their chemical similarities. All of the deployed separation methods rely on thermodynamic properties, such as distribution equilibria in solvent extraction. Rare-earth-metal separations based on kinetic differences have not been examined. Herein, we demonstrate a new approach for rare-earth-element separations by exploiting differences in the oxidation rates within a series of rare earth compounds containing the redox-active ligand [{2-(tBuN(O))C 6 H 4 CH 2 } 3 N] 3- . Using this method, a single-step separation factor up to 261 was obtained for the separation of a 50:50 yttrium-lutetium mixture. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Application of ICP-MS to Detect Rare Earth Elements in Three Economic Macroalgaes in China].

PubMed

Zhao, Yan-fang; Shang, De-rong; Zhai, Yu-xiu; Ning, Jin-song; Ding, Hai-yan; Sheng, Xiao-feng

2015-11-01

In order to investigate the content and distribution of rare earth elements (REE) in main economic macroalgaes in our country, fifteen rare earth elements in three economic macroalgaes (including 30 samples of kelp, 30 samples of laver and 15 samples of Enteromorpha) were detected using ICP-MS method. Results showed that the total content of REE in different species of macroalgaes was different. The highest total content of REE was in Enteromorpha (16,012.0 ng · g⁻¹), while in kelp and laver, the total REE was similar for two macroalgaes (3887.4 and 4318.1 ng · g⁻¹ respectively). The content of fifteen rare earth elements in kelp ranged from 7.9 to 1496.4 ng · g⁻¹; in laver, it ranged from 8.2 to 1836.6 ng · g⁻¹. For Enteromorpha, the concentration of 15 rare earth elements were between 19.2 and 6014.5 ng · g⁻¹. In addition, the content and distribution of different rare earth elements in different macroalgaes was also different. For kelp, the highest content of REE was Ce (1 496.4 ng · g⁻¹), and the second was La (689.1 ng · g⁻¹). For laver, the highest was Y (1836.6 ng · g⁻¹), and the second was Ce (682.2 ng · g⁻¹). For Enteromorpha, the highest was Ce (6014.5 ng · g⁻¹), and the second was La (2902.9 ng · g⁻¹). Present results also showed that three macroalgaes accumulated the light rare earth elements much more than the high rare earth elements. The light rare earth elements occupied 90.9%, 87.3% and 91.1% for kelp, laver and Enteromorpha respectively. The result that the Enteromorpha had high content of rare earth elements could provide important support for opening new research directions for the utilization of Enteromorpha.

Isosteric heat of water adsorption and desorption in homoionic alkaline-earth montmorillonites

NASA Astrophysics Data System (ADS)

Belhocine, M.; Haouzi, A.; Bassou, G.; Phou, T.; Maurin, D.; Bantignies, J. L.; Henn, F.

2018-02-01

The aim of the present work is to study by means of thermodynamic measurements and Infrared spectroscopy, the effect of the interlayer cations on the adsorption-desorption of water in the case of a montmorillonite exchanged with alkaline-earth metals. For the first time, the net isosteric heat of water adsorption and desorption is determined from isotherms recorded at three temperatures. The net isosteric heat is a very useful parameter for getting more insights into the sorption mechanism since it provides information about the sorption energy evolution which can be complementary to that obtained from structural or gravimetric measurements. The homoionic montmorillonite samples are prepared from purification and cationic exchanged in aqueous solution of the raw material, i.e. the reference SWy-2 Wyoming material. XRD at the dry state and elemental chemical analysis confirm that the treatment does not deteriorate the clay structure and yield the expected homoionic composition. The sorption isotherms measured at various temperatures show that the nature of the interlayer, i.e. exchangeable, cation changes the adsorbed/desorbed amount of water molecules for a given water relative pressure. The total amount of water adsorbed at P/P∘ = 0.5 follows the cation sequence Ca ∼ Mg>Ba while the sorption isosteric heats follow a slightly different sequence, i.e. Ca > Mg>Ba. This discrepancy between the adsorption and desorption heat is due to the higher irreversibility of water sorption process in the Ca exchanged montmorillonite. Finally, analysis of the IR spectra recorded at room temperature and under a primary vacuum reveals that the amount of adsorbed water follows the same sequence as that of the isosteric heat of adsorption and shows the coexistence of liquid-like and solid-like water confined in the interlayer space.

Assessing rare earth elements in quartz rich geological samples.

PubMed

Santoro, A; Thoss, V; Ribeiro Guevara, S; Urgast, D; Raab, A; Mastrolitti, S; Feldmann, J

2016-01-01

Sodium peroxide (Na2O2) fusion coupled to Inductively Coupled Plasma Tandem Mass Spectrometry (ICP-MS/MS) measurements was used to rapidly screen quartz-rich geological samples for rare earth element (REE) content. The method accuracy was checked with a geological reference material and Instrumental Neutron Activation Analysis (INAA) measurements. The used mass-mode combinations presented accurate results (only exception being (157)Gd in He gas mode) with recovery of the geological reference material QLO-1 between 80% and 98% (lower values for Lu, Nd and Sm) and in general comparable to INAA measurements. Low limits of detection for all elements were achieved, generally below 10 pg g(-1), as well as measurement repeatability below 15%. Overall, the Na2O2/ICP-MS/MS method proved to be a suitable lab-based method to quickly and accurately screen rock samples originating from quartz-rich geological areas for rare earth element content; particularly useful if checking commercial viability. Copyright © 2015 Elsevier Ltd. All rights reserved.

Rare Earth Element Concentrations in Submarine Hydrothermal Fluids

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

Fowler, Andrew; Zierenberg, Robert

Rare earth element concentrations in submarine hydrothermal fluids from Alarcon Rise, East Pacific Rise, REE concentrations in submarine hydrothermal fluids from Pescadero Basin, Gulf of California, and the Cleft vent field, southern Juan de Fuca Ridge. Data are not corrected to zero Mg.

Exploration of dysprosium: the most critical element for Japan

NASA Astrophysics Data System (ADS)

Watanabe, Y.

2012-04-01

Dysprosium (Dy), one of the heavy rare earth elements, is used mainly as an additive for NdFeB permanent magnets which are installed in various modern industrial products such as voice coil motors in computers, factory automation machinery, hybrid and electric vehicles, home electronics, and wind turbine, to improve heat resistance of the magnets. Dy has been produced about 2,000t per year from the ores from ion adsorption type deposits in southern China. However, the produced amount of Dy was significantly reduced in 2011 in China due to reservation of heavy rare earth resources and protection of natural environment, resulting in soaring of Dy price in the world. In order to respond the increasing demand of Dy, unconventional supply sources are inevitably developed, in addition to heavy rare earth enriched ion adsorption type deposits outside China. Heavy rare earth elements including Dy are dominantly hosted in xenotime, fergusonite, zircon, eudialyte, keiviite, kainosite, iimoriite, etc. Concentration of xenotime is found in placer deposits in Malaysia and India, hydrothermal deposits associated with unconformity-type uranium mineralization (Athabasca basin in Canada, Western Australia), iron-oxide fluorite mineralization (South Africa) and Sn-bearing alkaline granite (Brazil). Zircon and fergusontie concentration is found as igneous and hydrothermal products in peralkaline syenite, alkaline granite and pegmatite (e.g., Nechalacho in Canada). Eudialyte concentration is found in some peralkaline syenite bodies in Greenland, Canada, Sweden and Russia. Among these sources, large Dy resources are estimated in the deposits hosted in peralkaline rocks (Nechalacho: 79,000t, Kvanefjeld: 49,000t, Norra Karr: 15,700t, etc.) compared to the present demand of Dy. Thus, Dy will be supplied from the deposits associated with peralkaline and alkaline deposits in future instead of ion adsorption type deposits in southern China.

High-T sub c thin films on low microwave loss alkaline-rare-earth-aluminate crystals

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

Sobolewski, R.; Gierlowski, P.; Kula, W.

1991-03-01

This paper reports on the alkaline-rare-earth aluminates (K{sub 2}NiF{sub 4}-type perovskites) which are an excellent choice as the substrate material for the growth of high-T{sub c} thin films suitable for microwave and far-infrared applications. The CaNdAlO{sub 4}, and SrLaAlO{sub 4} single crystals have been grown by Czochralski pulling and fabricated into the form of (001) oriented wafers. The Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O films deposited on these substrates by a single-target magnetron sputtering exhibited very good superconducting and structural properties.

Chemical bonding analysis on amphoteric hydrogen - alkaline earth ammine borohydrides

NASA Astrophysics Data System (ADS)

Kiruthika, S.; Ravindran, P.

2018-04-01

Usually the ions in solid are in the positive oxidation states or in the negative oxidation state depending upon the chemical environment. It is highly unusual for an ion having both positive as well as negative oxidation state in a particular compound. Structural analysis suggest that the alkaline earth ammine borohydrides (AABH) with the chemical formula M (BH4)2(NH3)2 (M = Mg, Ca, or Sr) where hydrogen is present in +1 and -1 oxidation states. In order to understand the oxidation states of hydrogen and also the character of chemical bond present in AABH we have made charge density, electron localization function, Born effective charge, Bader effective charge, and density of states analyses using result from the density functional calculations. Our detailed analyses show that hydrogen is in amphoteric behavior with hydrogen closer to boron is in negative oxidation state and that closer to nitrogen is in the positive oxidation state. Due to the presence of finite covalent bonding between the consitutents in AABH the oxidation state of hydrogen is non-interger value. The confirmation of the presence of amphtoric behavior of hydrogen in AABH has implication in hydrogen storage applications.

Volatile elements - water, carbon, nitrogen, noble gases - on Earth

NASA Astrophysics Data System (ADS)

Marty, B.

2017-12-01

Understanding the origin and evolution of life-bearing volatile elements (water, carbon, nitrogen) on Earth is a fruitful and debated area of research. In his pioneering work, W.W. Rubey inferred that the terrestrial atmosphere and the oceans formed from degassing of the mantle through geological periods of time. Early works on noble gas isotopes were consistent with this view and proposed a catastrophic event of mantle degassing early in Earth's history. We now have evidence, mainly from noble gas isotopes, that several cosmochemical sources contributed water and other volatiles at different stages of Earth's accretion. Potential contributors include the protosolar nebula gas that equilibrated with magma oceans, inner solar system bodies now represented by chondrites, and comets. Stable isotope ratios suggest volatiles where primarily sourced by planetary bodies from the inner solar system. However, recent measurements by the European Space Agency Rosetta probe on the coma of Comet 67P/Churyumov-Gerasimenko permit to set quantitative constraints on the cometary contribution to the surface of our planet. The surface and mantle reservoirs volatile elements exchanged volatile elements through time, with rates that are still uncertain. Some mantle regions remained isolated from whole mantle convection within the first tens to hundreds million years after start of solar system formation. These regions, now sampled by some mantle plumes (e.g., Iceland, Eifel) preserved their volatile load, as indicated by extinct and extant radioactivity systems. The abundance of volatile elements in the mantle is still not well known. Different approaches, such as high pressure experimental petrology, noble gas geochemistry, modelling, resulted in somewhat contrasted estimates, varying over one order of magnitude for water. Comparative planetology, that is, the study of volatiles on the Moon, Venus, Mars, Vesta, will shed light on the sources and strengths of these elements in the

Concentrations and health risk assessment of rare earth elements in vegetables from mining area in Shandong, China.

PubMed

Zhuang, Maoqiang; Zhao, Jinshan; Li, Suyun; Liu, Danru; Wang, Kebo; Xiao, Peirui; Yu, Lianlong; Jiang, Ying; Song, Jian; Zhou, Jingyang; Wang, Liansen; Chu, Zunhua

2017-02-01

To investigate the concentrations of rare earth elements in vegetables and assess human health risk through vegetable consumption, a total of 301 vegetable samples were collected from mining area and control area in Shandong, China. The contents of 14 rare earth elements were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The total rare earth elements in vegetables from mining and control areas were 94.08 μg kg -1 and 38.67 μg kg -1 , respectively, and the difference was statistically significant (p < 0.05). The leaf vegetable had the highest rare earth elements concentration (984.24 μg kg -1 and 81.24 μg kg -1 for mining and control areas, respectively) and gourd vegetable had the lowest rare earth elements concentration (37.34 μg kg -1 and 24.63 μg kg -1 for mining and control areas, respectively). For both areas, the rare earth elements concentration in vegetables declined in the order of leaf vegetable > taproot vegetable > alliaceous vegetable > gourd vegetable. The rare earth elements distribution patterns for both areas were characterized by enrichment of light rare earth elements. The health risk assessment demonstrated that the estimated daily intakes (0.69 μg kg -1 d -1 and 0.28 μg kg -1 d -1 for mining and control areas, respectively) of rare earth elements through vegetable consumption were significantly lower than the acceptable daily intake (70 μg kg -1 d -1 ). The damage to adults can be neglected, but more attention should be paid to the effects of continuous exposure to low levels of rare earth elements on children. Copyright © 2016 Elsevier Ltd. All rights reserved.

Singular value decomposition approach to the yttrium occurrence in mineral maps of rare earth element ores using laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Romppanen, Sari; Häkkänen, Heikki; Kaski, Saara

2017-08-01

Laser-induced breakdown spectroscopy (LIBS) has been used in analysis of rare earth element (REE) ores from the geological formation of Norra Kärr Alkaline Complex in southern Sweden. Yttrium has been detected in eudialyte (Na15 Ca6(Fe,Mn)3 Zr3Si(Si25O73)(O,OH,H2O)3 (OH,Cl)2) and catapleiite (Ca/Na2ZrSi3O9·2H2O). Singular value decomposition (SVD) has been employed in classification of the minerals in the rock samples and maps representing the mineralogy in the sampled area have been constructed. Based on the SVD classification the percentage of the yttrium-bearing ore minerals can be calculated even in fine-grained rock samples.

Game meat authentication through rare earth elements fingerprinting.

PubMed

Danezis, G P; Pappas, A C; Zoidis, E; Papadomichelakis, G; Hadjigeorgiou, I; Zhang, P; Brusic, V; Georgiou, C A

2017-10-23

Accurate labelling of meat (e.g. wild versus farmed, geographical and genetic origin, organic versus conventional, processing treatment) is important to inform the consumers about the products they buy. Meat and meat products declared as game have higher commercial value making them target to fraudulent labelling practices and replacement with non-game meat. We have developed and validated a new method for authentication of wild rabbit meat using elemental metabolomics approach. Elemental analysis was performed using rapid ultra-trace multi-element measurement by inductively coupled plasma mass spectrometry (ICP-MS). Elemental signatures showed excellent ability to discriminate the wild rabbit from non-wild rabbit meat. Our results demonstrate the usefulness of metabolic markers -rare earth signatures, as well as other trace element signatures for game meat authentication. Copyright © 2017 Elsevier B.V. All rights reserved.

Spectroscopic identification of rare earth elements in phosphate glass

NASA Astrophysics Data System (ADS)

Devangad, Praveen; Tamboli, Maktum; Muhammed Shameem, K. M.; Nayak, Rajesh; Patil, Ajeetkumar; Unnikrishnan, V. K.; Santhosh, C.; Kumar, G. A.

2018-01-01

In this work, rare earth-doped phosphate glasses were synthesized and characterized using three different spectroscopic techniques. The absorption spectra of the prepared praseodymium (Pr) and samarium (Sm) doped glasses, recorded by a UV-VIS-NIR spectrophotometer, show the characteristic absorption bands of these elements. To confirm this inference, laser-induced fluorescence spectra of Pr and Sm were obtained at a laser excitation of 442 nm. Their emission bands are reported here. The elemental analysis of these samples was carried out using a laser-induced breakdown spectroscopy (LIBS) system. Characteristic emission lines of Pr and Sm have been identified and reported by the recorded LIBS spectra of glass samples. Results prove that using these three complimentary spectroscopic techniques (absorption, fluorescence and LIBS), we can meaningfully characterize rare earth-doped glass samples.

Alkaline earth silicate wools - A new generation of high temperature insulation.

PubMed

Brown, Robert C; Harrison, Paul T C

2012-11-01

Intensive study of the natural asbestiform minerals that cause human diseases, and the consequent understanding of their hazardous characteristics, has enabled the development of manufactured fibres whose physical and/or chemical properties, in particular as they relate to biopersistence, have been adjusted to minimize possible harm to health. A strong driver for the developmentof new high temperature insulation materials wasthe perception of the toxicity of refractory ceramic fibres (RCF)and their classification in the EU as a category 2 carcinogen under Directive 67/548/EEC. Such classification carries with it the requirement for substitution by less hazardous materials. This paper focuses on the development of alkaline earth silicate (AES) wools as a new class of high temperature insulation with the capability of such substitution in a number of applications. These wools have only a low potential to cause harm because they do not persist in lung tissue once deposited, and have produced minimal effects in experimental test systems. AES wools are increasingly being used in a wide range of high temperature applications. Copyright © 2012 Elsevier Inc. All rights reserved.

Rare earth elements and permanent magnets (invited)

NASA Astrophysics Data System (ADS)

Dent, Peter C.

2012-04-01

Rare earth (RE) magnets have become virtually indispensible in a wide variety of industries such as aerospace, automotive, electronics, medical, and military. RE elements are essential ingredients in these high performance magnets based on intermetallic compounds RECo5, RE2TM17 (TM: transition metal), and RE2TM14B. Rare earth magnets are known for their superior magnetic properties—high induction, and coercive force. These properties arise due to the extremely high magnetocrystalline anisotropy made possible by unique 3d-4f interactions between transition metals and rare earths. For more than 40 years, these magnets remain the number one choice in applications that require high magnetic fields in extreme operating conditions—high demagnetization forces and high temperature. EEC produces and specializes in RECo5 and RE2TM17 type sintered magnets. Samarium and gadolinium are key RE ingredients in the powder metallurgical magnet production processes which include melting, crushing, jet milling, pressing, sintering, and heat treating. The magnetic properties and applications of these magnets will be discussed. We will also briefly discuss the past, current, and future of the permanent magnet business. Currently, over 95% of all pure rare earth oxides are sourced from China, which currently controls the market. We will provide insights regarding current and potential new magnet technologies and designer choices, which may mitigate rare earth supply chain issues now and into the future.

Scanning Electron Microscope-Cathodoluminescence Analysis of Rare-Earth Elements in Magnets.

PubMed

Imashuku, Susumu; Wagatsuma, Kazuaki; Kawai, Jun

2016-02-01

Scanning electron microscope-cathodoluminescence (SEM-CL) analysis was performed for neodymium-iron-boron (NdFeB) and samarium-cobalt (Sm-Co) magnets to analyze the rare-earth elements present in the magnets. We examined the advantages of SEM-CL analysis over conventional analytical methods such as SEM-energy-dispersive X-ray (EDX) spectroscopy and SEM-wavelength-dispersive X-ray (WDX) spectroscopy for elemental analysis of rare-earth elements in NdFeB magnets. Luminescence spectra of chloride compounds of elements in the magnets were measured by the SEM-CL method. Chloride compounds were obtained by the dropwise addition of hydrochloric acid on the magnets followed by drying in vacuum. Neodymium, praseodymium, terbium, and dysprosium were separately detected in the NdFeB magnets, and samarium was detected in the Sm-Co magnet by the SEM-CL method. In contrast, it was difficult to distinguish terbium and dysprosium in the NdFeB magnet with a dysprosium concentration of 1.05 wt% by conventional SEM-EDX analysis. Terbium with a concentration of 0.02 wt% in an NdFeB magnet was detected by SEM-CL analysis, but not by conventional SEM-WDX analysis. SEM-CL analysis is advantageous over conventional SEM-EDX and SEM-WDX analyses for detecting trace rare-earth elements in NdFeB magnets, particularly dysprosium and terbium.

Rare earth elements in weathering profiles and sediments of Minnesota: Implications for provenance studies

USGS Publications Warehouse

Morey, G.B.; Setterholm, D.R.

1997-01-01

The relative abundance of rare earth elements in sediments has been suggested as a tool for determining their source rocks. This correlation requires that weathering, erosion, and sedimentation do not alter the REE abundances, or do so in a predictable manner. We find that the rare earth elements are mobilized and fractionated by weathering, and that sediments derived from the weathered materials can display modifications of the original pattern of rare earth elements of some due to grain-size sorting of the weathered material. However, the REE distribution pattern of the provenance terrane can be recognized in the sediments.

The effect of melt composition on the partitioning of trace elements between titanite and silicate melt

NASA Astrophysics Data System (ADS)

Prowatke, S.; Klemme, S.

2003-04-01

The aim of this study is to systematically investigate the influence of melt composition on the partitioning of trace elements between titanite and different silicate melts. Titanite was chosen because of its important role as an accessory mineral, particularly with regard to intermediate to silicic alkaline and calc-alkaline magmas [e.g. 1] and of its relative constant mineral composition over a wide range of bulk compositions. Experiments at atmospheric pressure were performed at temperatures between 1150°C and 1050°C. Bulk compositions were chosen to represent a basaltic andesite (SH3 - 53% SiO2), a dacite (SH2 - 65 SiO2) and a rhyolite (SH1 - 71% SiO2). Furthermore, two additional experimental series were conducted to investigate the effect of Al-Na and the Na-K ratio of melts on partitioning. Starting materials consisted of glasses that were doped with 23 trace elements including some selected rare earth elements (La, Ce, Pr, Sm, Gd, Lu), high field strength elements (Zr, Hf, Nb, Ta) and large ion lithophile elements (Cs, Rb, Ba) and Th and U. The experimental run products were analysed for trace elements using secondary ion mass spectrometry at Heidelberg University. Preliminary results indicate a strong effect of melt composition on trace element partition coefficients. Partition coefficients for rare-earth elements uniformly show a convex-upward shape [2, 3], since titanite accommodates the middle rare-earth elements more readily than the light rare-earth elements or the heavy rare-earth elements. Partition coefficients for the rare-earth elements follow a parabolic trend when plotted against ionic radius. The shape of the parabola is very similar for all studied bulk compositions, the position of the parabola, however, is strongly dependent on bulk composition. For example, isothermal rare-earth element partition coefficients (such as La) are incompatible (D<1) in alkali-rich silicate melts and strongly compatible (D>>1) in alkali-poor melt compositions

Statistical Constraints from Siderophile Elements on Earth's Accretion, Differentiation, and Initial Core Stratification

NASA Astrophysics Data System (ADS)

O'Rourke, J. G.; Stevenson, D. J.

2015-12-01

Abundances of siderophile elements in the primitive mantle constrain the conditions of Earth's core/mantle differentiation. Core growth occurred as Earth accreted from collisions between planetesimals and larger embryos of unknown original provenance, so geochemistry is directly related to the overall dynamics of Solar System formation. Recent studies claim that only certain conditions of equilibration (pressure, temperature, and oxygen fugacity) during core formation can reproduce the available data. Typical analyses, however, only consider the effects of varying a few out of tens of free parameters in continuous core formation models. Here we describe the Markov chain Monte Carlo method, which simultaneously incorporates the large uncertainties on Earth's composition and the parameterizations that describe elemental partitioning between metal and silicate. This Bayesian technique is vastly more computationally efficient than a simple grid search and is well suited to models of planetary accretion that involve a plethora of variables. In contrast to previous work, we find that analyses of siderophile elements alone cannot yield a unique scenario for Earth's accretion. Our models predict a wide range of possible light element contents for the core, encompassing all combinations permitted by seismology and mineral physics. Specifically, we are agnostic between silicon and oxygen as the dominant light element, and the addition of carbon or sulfur is also permissible but not well constrained. Redox conditions may have remained roughly constant during Earth's accretion or relatively oxygen-rich material could have been incorporated before reduced embryos. Pressures and temperatures of equilibration, likewise, may only increase slowly throughout accretion. Therefore, we do not necessarily expect a thick (>500 km), compositionally stratified layer that is stable against convection to develop at the top of the core of Earth (or, by analogy, Venus). A thinner stable layer

Alkaline sorbent injection for mercury control

DOEpatents

Madden, Deborah A.; Holmes, Michael J.

2003-01-01

A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

Alkaline sorbent injection for mercury control

DOEpatents

Madden, Deborah A.; Holmes, Michael J.

2002-01-01

A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

Dissolution of glass wool, rock wool and alkaline earth silicate wool: morphological and chemical changes in fibers.

PubMed

Campopiano, Antonella; Cannizzaro, Annapaola; Angelosanto, Federica; Astolfi, Maria Luisa; Ramires, Deborah; Olori, Angelo; Canepari, Silvia; Iavicoli, Sergio

2014-10-01

The behavior of alkaline earth silicate (AES) wool and of other biosoluble wools in saline solution simulating physiological fluids was compared with that of a traditional wool belonging to synthetic vitreous fibers. Morphological and size changes of fibers were studied by scanning electron microscopy (SEM). The elements extracted from fibers were analyzed by inductively coupled plasma atomic emission spectrometry. SEM analysis showed a larger reduction of length-weighted geometric mean fiber diameter at 4.5 pH than at 7.4 pH. At the 7.4 pH, AES wool showed a higher dissolution rate and a dissolution time less than a few days. Their dissolution was highly non-congruent with rapid leaching of calcium. Unlike rock wool, glass wool dissolved more rapidly at physiological pH than at acid pH. Dissolution of AES and biosoluble rock wool is accompanied by a noticeable change in morphology while by no change for glass wool. Biosoluble rock wool developed a leached surface with porous honeycomb structure. SEM analysis showed the dissolution for glass wool is mainly due to breakage transverse of fiber at pH 7.4. AES dissolution constant (Kdis) was the highest at pH 7.4, while at pH 4.5 only biosoluble rockwool 1 showed a higher Kdis. Copyright © 2014 Elsevier Inc. All rights reserved.

The luminescence and decay enhancement by variation in atomic size of alkaline earth metals in Pr3+ incorporated sodium lead borate glass

NASA Astrophysics Data System (ADS)

Lenkennavar, Susheela K.; Madhu, A.; Eraiah, B.; Kokila, M. K.

2018-05-01

The glasses used for the present study are prepared by the melting and quenching techniques of composition 20Na2O-10PbO-10MO-60B2O3-xPr2O3 (where, M=Ba, Ca, Sr and x= 0.5 mol% of Pr3+). For different alkaline considered with same Pr3+ concemtartion incorporation on present work as resulted in interesting facts. Due to the effect of different atomic size, the luminescence and life time of glasses are affected. Only for calcium alkaline earth metal incorporated samples has proved to have highest intensity in emission and longer life time. The detailed studies of them have been reported for the better understanding.

Loparite-(Ce) from the Khibiny Alkaline Pluton, Kola Peninsula, Russia

NASA Astrophysics Data System (ADS)

Konopleva, N. G.; Ivanyuk, G. Yu.; Pakhomovsky, Ya. A.; Yakovenchuk, V. N.; Mikhailova, Yu. A.

2017-12-01

Data on the occurrence, morphology, anatomy, composition, and formation conditions of loparite-(Ce) in the Khibiny alkaline pluton are given. Loparite-(Ce), (Na,Ce,Sr)(Ce,Th)(Ti,Nb)2O6, resulted from metasomatic alteration and assimilation of metamorphic host rocks at the contact with foyaite as well as foyaite on the contact with foidolite. This alteration was the highest in pegmatite, and albitite developed there. A decrease in temperature resulted in enrichment of the perovskite and tausonite endmembers in loparite-(Ce) owing to a decrease in the loparite and lueshite endmembers. La and Ce sharply predominate among rare earth elements in the composition of loparite-(Ce).

A model for Nb-Zr-REE-Ga enrichment in Lopingian altered alkaline volcanic ashes: Key evidence of H-O isotopes

NASA Astrophysics Data System (ADS)

Dai, Shifeng; Nechaev, Victor P.; Chekryzhov, Igor Yu.; Zhao, Lixin; Vysotskiy, Sergei V.; Graham, Ian; Ward, Colin R.; Ignatiev, Alexander V.; Velivetskaya, Tatyana A.; Zhao, Lei; French, David; Hower, James C.

2018-03-01

Clay-altered volcanic ash with highly-elevated concentrations of Nb(Ta), Zr(Hf), rare earth elements (REE), and Ga, is a new type of critical metal deposit with high commercial prospects that has been discovered in Yunnan Province, southwest China. Previous studies showed that the volcanic ashes had been subjected to hydrothermal fluids, the nature of which, however, is not clear. Here we show that the volcanic ashes were originated from alkaline magmatism, followed by a continuous hydrothermal-weathering process. Heated meteoric waters, which were sourced from acidic rains and mixed with CO2 from degassing of the Emeishan plume, have caused partial, but widespread, acidic leaching of Nb, Ta, Zr, Hf, REE, and Ga into ground water and residual enrichment of these elements, along with Al and Ti, in the deeply altered rocks. Subsequent alteration occurring under cooler, neutral or alkaline conditions, caused by water-rock interaction, resulted in precipitation of the leached critical metals in the deposit. Polymetallic mineralization of similar origin may be found in other continental regions subjected to explosive alkaline volcanism associated with deep weathering in humid conditions.

Characteristics and genesis of Rare Earth Element (REE) in western Indonesia

NASA Astrophysics Data System (ADS)

Handoko, A. D.; Sanjaya, E.

2018-02-01

Rare Earth Element (REE) has unique properties that have been used in many hightech applications. The demand of REE increased recently in the world due to its special properties. Although REE concentration in the crust is higher than gold, economically viable deposits are still rare. Reduction of REE exports by China cause increased prices of REE. Due to this condition, exploration of potential REE mines emerged. Indonesia also participates in this phenomenon, and explore the possibility of REE mines in its area. This review will discuss the characteristics and genesis of REE and its occurrence in western Indonesia; focused in Sumatera, Tin Island, and Kalimantan. The review is done based on literature research from several resources about characteristics of rare earth element in general and in the given area. The research shows that the potential REE mines can be found in several different locations in Indonesia, such as Tin Island, Sumatera, and Kalimantan. Most of them are composed of monazite, zircon, and xenotime as rare earth minerals. Monazite iss known for its elevated number of radioactive elements, so study about radioactive content and more environment friendly ore processing becomes compulsory.

Element Abundances in Meteorites and the Earth: Implication for the Accretion of Planetary Bodies

NASA Astrophysics Data System (ADS)

Mezger, K.; Vollstaedt, H.; Maltese, A.

2017-12-01

Essentially all known inner solar system materials show near chondritic relative abundances of refractory elements and depletion in volatile elements. To a first approximation volatile element depletion correlates with the respective condensation temperature (TC) of the elements. Possible mechanisms for this depletion are incomplete condensation and partial loss by evaporation caused by heating prior to or during the planetesimal accretion. The stable isotope compositions of almost all moderately volatile elements in different meteorite classes show only minor, or no evidence for a Rayleigh-type fractionation that could be attributed to partial condensation or evaporation. The different classes of meteorites also show that the degree of depletion in their parent bodies (i.e. mostly planetesimals) is quite variable, but nevertheless systematic. For primitive and least disturbed carbonaceous chondrites the element depletion pattern is a smooth function of TC. The accessible silicate Earth also shows this general depletion pattern, but in detail it is highly complex and requires differentiation processes that are not solely controlled by TC. If only highly lithophile elements are considered the depletion pattern of the silicate Earth reveals a step function that shows that moderately volatile lithophile elements have abundances that are ca. 0.1 times the chondritic value, irrespective of their TC. This element pattern observed for bulk silicate Earth can be modelled as a mixture of two distinct components: ca. 90% of a strongly reduced planetary body that is depleted in highly volatile elements and ca. 10% of a more volatile element rich and oxidized component. This mixture can account for the apparent Pb- paradox observed in melts derived from the silicate Earth and provides a time constraint for the mixing event, which is ca. 70 My after the beginning of the solar system. This event corresponds to the giant impact that also formed the Moon.

Alkaline earth metal and samarium co-doped ceria as efficient electrolytes

NASA Astrophysics Data System (ADS)

Ali, Amjad; Raza, Rizwan; Kaleem Ullah, M.; Rafique, Asia; Wang, Baoyuan; Zhu, Bin

2018-01-01

Co-doped ceramic electrolytes M0.1Sm0.1Ce0.8O2-δ (M = Ba, Ca, Mg, and Sr) were synthesized via co-precipitation. The focus of this study was to highlight the effects of alkaline earth metals in doped ceria on the microstructure, densification, conductivity, and performance. The ionic conductivity comparisons of prepared electrolytes in the air atmosphere were studied. It has been observed that Ca0.1Sm0.1Ce0.8O2-δ shows the highest conductivity of 0.124 Scm-1 at 650 °C and a lower activation energy of 0.48 eV. The cell shows a maximum power density of 630 mW cm-2 at 650 °C using hydrogen fuel. The enhancement in conductivity and performance was due to increasing the oxygen vacancies in the ceria lattice with the increasing dopant concentration. The bandgap was calculated from UV-Vis data, which shows a red shift when compared with pure ceria. The average crystallite size is in the range of 37-49 nm. DFT was used to analyze the co-doping structure, and the calculated lattice parameter was compared with the experimental lattice parameter.

Tipping elements in the Earth's climate system.

PubMed

Lenton, Timothy M; Held, Hermann; Kriegler, Elmar; Hall, Jim W; Lucht, Wolfgang; Rahmstorf, Stefan; Schellnhuber, Hans Joachim

2008-02-12

The term "tipping point" commonly refers to a critical threshold at which a tiny perturbation can qualitatively alter the state or development of a system. Here we introduce the term "tipping element" to describe large-scale components of the Earth system that may pass a tipping point. We critically evaluate potential policy-relevant tipping elements in the climate system under anthropogenic forcing, drawing on the pertinent literature and a recent international workshop to compile a short list, and we assess where their tipping points lie. An expert elicitation is used to help rank their sensitivity to global warming and the uncertainty about the underlying physical mechanisms. Then we explain how, in principle, early warning systems could be established to detect the proximity of some tipping points.

Low frequency vibrational spectra and the nature of metal-oxygen bond of alkaline earth metal acetylacetonates

NASA Astrophysics Data System (ADS)

Fakheri, Hamideh; Tayyari, Sayyed Faramarz; Heravi, Mohammad Momen; Morsali, Ali

2017-12-01

Theoretical quantum chemistry calculations were used to assign the observed vibrational band frequencies of Be, Mg, Ca, Sr, and Ba acetylacetonates complexes. Density functional theory (DFT) calculations have been carried out at the B3LYP level, using LanL2DZ, def2SVP, and mixed, GenECP, (def2SVP for metal ions and 6-311++G** for all other atoms) basis sets. The B3LYP level, with mixed basis sets, was utilized for calculations of vibrational frequencies, IR intensity, and Raman activity. Analysis of the vibrational spectra indicates that there are several bands which could almost be assigned mainly to the metal-oxygen vibrations. The strongest Raman band in this region could be used as a measure of the stability of the complex. The effects of central metal on the bond orders and charge distributions in alkaline earth metal acetylacetonates were studied by the Natural Bond Orbital (NBO) method for fully optimized compounds. Optimization were performed at the B3LYP/6-311++G** level for the lighter alkaline earth metal complexes (Be, Mg, and Ca acetylacetonates) while the B3LYP level, using LanL2DZ (extrabasis, d and f on oxygen and metal atoms), def2SVP and mixed (def2SVP on metal ions and 6-311++G** for all other atoms) basis sets for all understudy complexes. Calculations indicate that the covalence nature of metal-oxygen bonds considerably decreases from Be to Ba complexes. The nature of metal-oxygen bond was further studied by using Atoms In Molecules (AIM) analysis. The topological parameters, Wiberg bond orders, natural charges of O and metal ions, and also some vibrational band frequencies were correlated with the stability constants of understudy complexes.

RARE EARTH ELEMENTS: A REVIEW OF PRODUCTION, PROCESSING, RECYCLING, AND ASSOCIATED ENVIRONMENTAL ISSUES

EPA Science Inventory

Rare earth elements (REEs) are a group of 15 chemical elements in the periodic table, specifically the lanthanides. Two other elements, scandium and yttrium, have a similar physiochemistry to the lanthanides, are commonly found in the same mineral assemblages, and are often refe...

Generation of alkaline magmas in subduction zones by melting of mélange diapirs

NASA Astrophysics Data System (ADS)

Cruz-Uribe, A. M.; Marschall, H.; Gaetani, G. A.; Le Roux, V.

2016-12-01

and Na), and depletion in Nb and Ta. The presence of a light rare earth element (LREE)-bearing accessory phase results in trace element fractionation by a factor of 4.2 for Nd/Hf and 2.6 for Sr/Nd. Melting of mélange diapirs provides a simple, single-stage model for the origin of alkaline magmatism in the arc and backarc regions of subduction zones.

Prolonged QT Syndrome and Seizure Secondary to Alkaline Earth Metal Deficiency: A Case Report.

PubMed

McKinney, A; Keegan, B C

2011-01-01

Introduction. Alkaline earth metal deficiency is recognized as a cause of both seizure and long QT syndrome. Their deficiency can have significant repercussions on the function of cells, tissues, and organs of the body. An understanding of the role of electrolytes allows an appreciation of the significance of depleted levels on cell function. Case Report. A 65-year-old lady was admitted with symptoms of chest discomfort, vomiting, increased stoma output, and dizziness. Two days following admission she suffered a tonic-clonic seizure. ECG review demonstrated a prolonged QTc interval, raising the possibility of an underlying Torsades de Pointes as the precipitant. This was attributed to electrolyte disturbance arising as a result of multiple aetiologies. Discussion. This paper highlights the multisystem effects of electrolyte disturbance, with emphasis upon its role in precipitating cardiac arrhythmia and neurological symptoms.

RARE EARTH ELEMENTS IN FLY ASHES AS POTENTIAL INDICATORS OF ANTHROPOGENIC SOIL CONTAMINATION

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

Mattigod, Shas V.

2003-08-01

Studies of rare earth element (REE) content of disposed fly ashes and their potential mobility were neglected for decades because these elements were believed to be environmentally benign. A number of recent studies have now shown that REE may pose a long-term risk to the biosphere. Therefore, there is a critical need to study the REE concentrations in fly ash and their potential mobilization and dispersal upon disposal in the environment. We analyzed the REE content of bulk, size fractionated, and density separated fractions of three fly ash samples derived from combustion of sub bituminous coals from the western Unitedmore » States and found that the concentrations of these elements in bulk ashes were within the range typical of fly ashes derived from coals from the North American continent. The concentrations of light rare earth elements (LREE) such as La, Ce, and Nd, however, tended towards the higher end of the concentration range whereas, the concentrations of middle rare earth elements (MREE) (Sm and Eu) and heavy rare earth elements (HREE) (Lu) were closer to the lower end of the observed range for North American fly ashes. The concentrations of REE did not show any significant enrichment with decreasing particle size, this is typical of nonvolatile lithophilic element behavior during the combustion process. The lithophilic nature of REE was also confirmed by their concentrations in heavy density fractions of these fly ashes being on average about two times more enriched than the concentrations in the light density fractions. Shale normalized average of REE concentrations of fly ashes and coals revealed significant positive anomalies for Eu and Dy. Because of these distinctive positive anomalies of Eu and Dy, we believe that fly ash contamination of soils can be fingerprinted and distinguished from other sources of anthropogenic REE inputs in to the environment.« less

Indirect ultraviolet detection of alkaline earth metal ions using an imidazolium ionic liquid as an ultraviolet absorption reagent in ion chromatography.

PubMed

Liu, Yong-Qiang; Yu, Hong

2017-04-01

A convenient and versatile method was developed for the separation and detection of alkaline earth metal ions by ion chromatography with indirect UV detection. The chromatographic separation of Mg 2+ , Ca 2+ , and Sr 2+ was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid as the mobile phase, in which the imidazolium ionic liquid acted as an UV-absorption reagent. The effects of imidazolium ionic liquids, detection wavelength, acids in the mobile phase, and column temperature on the retention of Mg 2+ , Ca 2+ , and Sr 2+ were investigated. The main factors influencing the separation and detection were the background UV absorption reagent and the concentration of hydrogen ion in ion chromatography with indirect UV detection. The successful separation and detection of Mg 2+ , Ca 2+ , and Sr 2+ within 14 min were achieved using the selected chromatographic conditions, and the detection limits (S/N = 3) were 0.06, 0.12, and 0.23 mg/L, respectively. A new separation and detection method of alkaline earth metal ions by ion chromatography with indirect UV detection was developed, and the application range of ionic liquids was expanded. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermoelectric Properties of Barium Plumbate Doped by Alkaline Earth Oxides

NASA Astrophysics Data System (ADS)

Eufrasio, Andreza; Bhatta, Rudra; Pegg, Ian; Dutta, Biprodas

Ceramic oxides are now being considered as a new class of thermoelectric materials because of their high stability at elevated temperatures. Such materials are especially suitable for use as prospective thermoelectric power generators because high temperatures are encountered in such operations. The present investigation uses barium plumbate (BaPbO3) as the starting material, the thermoelectric properties of which have been altered by judicious cation substitutions. BaPbO3 is known to exhibit metallic properties which may turn semiconducting as a result of compositional changes without precipitating a separate phase and/or altering the basic perovskite crystal structure. Perovskite structures are noted for their large interstitial spaces which can accommodate a large variety of ``impurity'' ions. As BaPbO3 has high electrical conductivity, σ = 2.43x105Ω-1 m-1 at room temperature, its thermopower, S, is relatively low, 23 μV/K, as expected. With a thermal conductivity, k, of 4.83Wm-1K-1, the figure of merit (ZT =S2 σ Tk-1) of BaPbO3 is only 0.01 at T = 300K. The objective of this investigation is to study the variation of thermoelectric properties of BaPbO3 as Ba and Pb ions are systematically substituted by alkaline earth ions.

Rare Earth Elements in Alberta Oil Sand Process Streams

DOE PAGES

Roth, Elliot; Bank, Tracy; Howard, Bret; ...

2017-04-05

The concentrations of rare earth elements in Alberta, Canada oil sands and six oil sand waste streams were determined using inductively coupled plasma mass spectrometry (ICP–MS). The results indicate that the rare earth elements (REEs) are largely concentrated in the tailings solvent recovery unit (TSRU) sample compared to the oil sand itself. The concentration of lanthanide elements is ~1100 mg/kg (1100 ppm or 0.11 weight %), which represents a >20× increase in the concentration compared to the oil sand itself and a >7× increase compared to the North American Shale Composite (NASC). The process water, which is used to extractmore » the oil from oil sands, and the water fraction associated with the different waste streams had very low concentrations of REEs that were near or below the detection limits of the instrument, with the highest total concentration of REEs in the water fraction being less than 10 μg/L (ppb). Size and density separations were completed, and the REEs and other potentially interesting and valuable metals, such as Ti and Zr, were concentrated in different fractions. These results give insights into the possibility of recovering REEs from waste streams generated from oil sand processing.« less

Rare Earth Elements in Alberta Oil Sand Process Streams

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

Roth, Elliot; Bank, Tracy; Howard, Bret

The concentrations of rare earth elements in Alberta, Canada oil sands and six oil sand waste streams were determined using inductively coupled plasma mass spectrometry (ICP–MS). The results indicate that the rare earth elements (REEs) are largely concentrated in the tailings solvent recovery unit (TSRU) sample compared to the oil sand itself. The concentration of lanthanide elements is ~1100 mg/kg (1100 ppm or 0.11 weight %), which represents a >20× increase in the concentration compared to the oil sand itself and a >7× increase compared to the North American Shale Composite (NASC). The process water, which is used to extractmore » the oil from oil sands, and the water fraction associated with the different waste streams had very low concentrations of REEs that were near or below the detection limits of the instrument, with the highest total concentration of REEs in the water fraction being less than 10 μg/L (ppb). Size and density separations were completed, and the REEs and other potentially interesting and valuable metals, such as Ti and Zr, were concentrated in different fractions. These results give insights into the possibility of recovering REEs from waste streams generated from oil sand processing.« less

Production and precipitation of rare earth elements in acidic to alkaline coal mine discharges, Appalachian Basin, USA

NASA Astrophysics Data System (ADS)

Stewart, B. W.; Capo, R. C.; Hedin, B. C.; Wallrich, I. L. R.; Hedin, R. S.

2016-12-01

Abandoned coal mine discharges are a serious threat to ground and surface waters due to their high metal content and often high acidity. However, these discharges represent a potential source of rare earth elements (REE), many of which are considered to be critical resources. Trace element data from 18 coal mine drainage (CMD) sites within the Appalachian Basin suggest CMD is enriched in total REE by 1-4 orders of magnitude relative to concentrations expected in unaffected surface or ground waters. When normalized to the North American Shale Composite (NASC), the discharges generally show a pattern of enrichment in the middle REE, including several identified as critical resources (Nd, Eu, Dy, Tb). In contrast, shale, sandstone and coal samples from Appalachian Basin coal-bearing units have concentrations and patterns similar to NASC, indicating that the REE in CMD are fractionated during interaction with rock in the mine pool. The highest total REE contents (up to 2800 mg/L) are found in low-pH discharges (acid mine drainage, or AMD). A precipitous drop in REE concentration in CMD with pH ≥6.6 suggests adsorption or precipitation of REE in the mine pool at circumneutral pH. Precipitated solids from 21 CMD active and passive treatment sites in the Appalachian Basin, including Fe oxy-hydroxides, Ca-Mg lime slurries, and Si- and Al-rich precipitates, are enriched in total REE content relative to the average CMD discharges by about four orders of magnitude. Similar REE trends in the discharges and precipitates, including MREE enrichment, suggest minimal fractionation of REE during precipitation; direct comparisons over multiple seasonal cycles are needed to confirm this. Although the data are limited, Al-rich precipitates generally have high REE concentrations, while those in iron oxy-hydroxides tend to be lower. Based on the area of mined coal in the Appalachian Basin, estimated infiltration rates, and the mean REE flux from discharges analyzed in this study and

[Rare earth elements contents and distribution characteristics in nasopharyngeal carcinoma tissue].

PubMed

Zhang, Xiangmin; Lan, Xiaolin; Zhang, Lingzhen; Xiao, Fufu; Zhong, Zhaoming; Ye, Guilin; Li, Zong; Li, Shaojin

2016-03-01

To investigate the rare earth elements(REEs) contents and distribution characteristics in nasopharyngeal carcinoma( NPC) tissue in Gannan region. Thirty patients of NPC in Gannan region were included in this study. The REEs contents were measured by tandem mass spectrometer inductively coupled plasma(ICP-MS/MS) in 30 patients, and the REEs contents and distribution were analyzed. The average standard deviation value of REEs in lung cancer and normal lung tissues was the minimum mostly. Light REEs content was higher than the medium REEs, and medium REEs content was higher than the heavy REEs content. REEs contents changes in nasopharyngeal carcinoma were variable obviously, the absolute value of Nd, Ce, Pr, Gd and other light rare earth elements were variable widely. The degree of changes on Yb, Tb, Ho and other heavy rare earth elements were variable widely, and there was presence of Eu, Ce negative anomaly(δEu=0. 385 5, δCe= 0. 523 4). The distribution characteristic of REEs contents in NPC patients is consistent with the parity distribution. With increasing atomic sequence, the content is decline wavy. Their distribution patterns were a lack of heavy REEs and enrichment of light REEs, and there was Eu , Ce negative anomaly.

A LOW-COST RARE EARTH ELEMENTS RECOVERY TECHNOLOGY - PHASE I

EPA Science Inventory

A first report of rare earth elements in northwestern Mediterranean seaweeds.

PubMed

Squadrone, Stefania; Brizio, Paola; Battuello, Marco; Nurra, Nicola; Sartor, Rocco Mussat; Benedetto, Alessandro; Pessani, Daniela; Abete, Maria Cesarina

2017-09-15

The concentrations of rare earth elements (REE) were determined by ICP-MS in dominant seaweed species, collected from three locations of the northwestern Mediterranean Sea. This is the first study to define levels and patterns of REE in macro algae from these coastal areas. Rare elements are becoming emerging inorganic contaminants in marine ecosystems, due to their worldwide increasing applications in industry, technology, medicine and agriculture. Significant inter-site and interspecies differences were registered, with higher levels of REE in brown and green macro algae than in red seaweeds. Levels of light REE were also observed to be greater compared to heavy REE in all samples. One of the investigated locations (Bergeggi, SV) had higher REE and ΣREE concentrations, probably due to its proximity to an important commercial and touristic harbor, while the other two sites were less affected by anthropogenic contaminations, and showed comparable REE patterns and lower concentrations. Rare earth elements in seaweeds. Copyright © 2017 Elsevier Ltd. All rights reserved.

The History and Use of Our Earth's Chemical Elements: A Reference Guide (by Robert E. Krebs)

NASA Astrophysics Data System (ADS)

Bracken, Reviewed By Jeffrey D.

1999-04-01

Greenwood Press: Westport, CT, 1998. 282 pp + 25 pp glossary + 37 pp index. 15.9 x 24.1 cm. ISBN 0-313-30123-9. $39.95. This book is an excellent resource for chemical educators at the high school and college levels. The format of the text is consistent and the writing style is clear and concise, making it ideally suited for student use also. The first three chapters serve to introduce the reader to a brief history of chemistry, early models of the atom, and the development of the periodic table. Names of the contributing scientists are mentioned whenever necessary, but the overall purpose of these introductory chapters is simply to lay a foundation for the subsequent seven chapters. A complete glossary of important scientific terms mentioned in the text should allow beginning students to use this book without feeling overwhelmed. Each entry for the 112 elements contains the following information: elemental symbol, atomic number, period, common valence, atomic weight, natural state, common isotopes, properties, characteristics, abundance, natural sources, history, common uses and compounds, and safety hazards. This information is well organized, with clear headings and separate sections making the book extremely user-friendly. Readers can easily obtain the information they desire without having to skim the full entry for a chosen element. One very nice feature of this book is that the elements entries are arranged by their locations in the periodic table. For example, chapter 4 contains the alkali metals and alkaline earth metals. This organizational scheme allows one to quickly see the patterns and trends within groups of elements. This format is significantly better than arranging the elements in alphabetical order, which places the entry for sodium far removed from the entries for lithium and potassium. I would highly recommend this book to high school teachers and college chemistry professors. It is well written and is an excellent source of information for

Equilibrium distribution of rare earth elements between molten KCl-LiCl eutectic salt and liquid cadmium

NASA Astrophysics Data System (ADS)

Sakata, Masahiro; Kurata, Masaki; Hijikata, Takatoshi; Inoue, Tadashi

1991-11-01

Distribution experiments for several rare earth elements (La, Ce, Pr, Nd and Y) between molten KCl-LiCl eutectic salt and liquid Cd were carried out at 450, 500 and 600°C. The material balance of rare earth elements after reaching the equilibrium and their distribution and chemical states in a Cd sample frozen after the experiment were examined. The results suggested the formation of solid intermetallic compounds at the lower concentrations of rare earth metals dissolved in liquid Cd than those solubilities measured in the binary alloy system. The distribution coefficients of rare earth elements between two phases (mole fraction in the Cd phase divided by mole fraction in the salt phase) were determined at each temperature. These distribution coefficients were explained satisfactorily by using the activity coefficients of chlorides and metals in salt and Cd. Both the activity coefficients of metal and chloride caused a much smaller distribution coefficient of Y relative to those of other elements.

A miniature single element effusion cell for the vacuum deposition of transition-metal and rare-earth elements

NASA Astrophysics Data System (ADS)

Harris, V. G.; Koon, N. C.

1997-08-01

A miniature single element effusion cell has been fabricated and tested that allows for the high-vacuum deposition of a variety of transition-metal and rare-earth elements. The cell is designed to operate under high-vacuum conditions, ≈10-9 Torr, with low power demands, <200 W. The virtues of this evaporator are the simplicity of design and ease of fabrication, assembly, maintenance, and operation.

Mineralogical, petrological and geochemical aspects of alkaline and alkaline-carbonatite associations from Brazil

NASA Astrophysics Data System (ADS)

Morbidelli, L.; Gomes, C. B.; Beccaluva, L.; Brotzu, P.; Conte, A. M.; Ruberti, E.; Traversa, G.

1995-12-01

A general description of Mesozoic and Tertiary (Fortaleza) Brazilian alkaline and alkaline-carbonatite districts is presented with reference to mineralogy, petrology, geochemistry and geochronology. It mainly refers to scientific results obtained during the last decade by an Italo-Brazilian research team. Alkaline occurrences are distributed across Brazilian territory from the southern (Piratini, Rio Grande do Sul State) to the northeastern (Fortaleza, Ceará State) regions and are mainly concentrated along the borders of the Paraná Basin generally coinciding with important tectonic lineaments. The most noteworthy characteristics of these alkaline and alkaline-carbonatite suites are: (i) prevalence of intrusive forms; (ii) abundance of cumulate assemblages (minor dunites, frequent clinopyroxenites and members of the ijolite series) and (iii) abundance of evolved rock-types. Many data demonstrate that crystal fractionation was the main process responsible for magma evolution of all Brazilian alkaline rocks. A hypothesis is proposed for the genesis of carbonatite liquids by immiscibility processes. The incidence of REE and trace elements for different major groups of lithotypes, belonging both to carbonatite-bearing and carbonatite-free districts, are documented. Sr and preliminary Nd isotopic data are indicative of a mantle origin for the least evolved magmas of all the studied occurrences. Mantle source material and melting models for the generation of the Brazilian alkaline magma types are also discussed.

Bacterial Cell Surface Adsorption of Rare Earth Elements

NASA Astrophysics Data System (ADS)

Jiao, Y.; Park, D.; Reed, D.; Fujita, Y.; Yung, M.; Anderko, A.; Eslamimanesh, A.

2015-12-01

Rare earth elements (REE) play a critical role in many emerging clean energy technologies, including high-power magnets, wind turbines, solar panels, hybrid/electric vehicle batteries and lamp phosphors. In order to sustain demand for such technologies given current domestic REE shortages, there is a need to develop new approaches for ore processing/refining and recycling of REE-containing materials. To this end, we have developed a microbially-mediated bioadsorption strategy with application towards enrichment of REE from complex mixtures. Specifically, the bacterium Caulobacter crescentus was genetically engineered to display lanthanide binding tags (LBTs), short peptides that possess high affinity and specificity for rare earth elements, on its cell surface S-layer protein. Under optimal conditions, LBT-displayed cells adsorbed greater than 5-fold more REE than control cells lacking LBTs. Competition binding experiments with a selection of REEs demonstrated that our engineered cells could facilitate separation of light- from heavy- REE. Importantly, binding of REE onto our engineered strains was much more favorable compared to non-REE metals. Finally, REE bound to the cell surface could be stripped off using citrate, providing an effective and non-toxic REE recovery method. Together, this data highlights the potential of our approach for selective REE enrichment from REE containing mixtures.

Fractionation of rare earth elements in the Mississippi River estuary and river sediments

NASA Astrophysics Data System (ADS)

Adebayo, S. B.; Johannesson, K. H.

2017-12-01

This study presents the first set of data on the fractionation of rare earth elements (REE) in the mixing zone between the Mississippi River and the Gulf of Mexico, as well as the fractionation of REE in the operationally defined fractions of Mississippi River sediments. This subject is particularly important because the Mississippi river is one of the world's major rivers, and contributes a substantial amount of water and sediment to the ocean. Hence, it is a major source of trace elements to the oceans. The geochemistry of the REE in natural systems is principally important because of their unique chemical properties, which prompt their application as tracers of mass transportation in modern and paleo-ocean environments. Another important consideration is the growth in the demand and utilization of REE in the green energy and technology industries, which has the potential to bring about a change in the background levels of these trace elements in the environment. The results of this study show a heavy REE enrichment of both the Mississippi River water and the more saline waters of the mixing zone. Our data demonstrate that coagulation and removal of REE in the low salinity region of the estuary is more pronounced among the Light REE ( 35% for Nd) compared to the Heavy REE. Remarkably, our data also indicate that REE removal in the Mississippi River estuary is significantly less than that observed in other estuaries, including the Amazon River system. We propose that the high pH/alkalinity of the Mississippi River is responsible for the greater stability of REE in the Mississippi River estuary. The results of sequential extraction of river sediments reveal different Sm/Nd ratios for the various fractions, which we submit implies different 143Nd/144Nd ratios of the labile fractions of the sediments. The possible impact of such hypothesized different Nd isotope signatures of labile fractions of the river sediments on Gulf of Mexico seawater is under investigation.

Uptake of alkaline earth metals in Alcyonarian spicules (Octocorallia)

NASA Astrophysics Data System (ADS)

Taubner, I.; Böhm, F.; Eisenhauer, A.; Garbe-Schönberg, D.; Erez, J.

2012-05-01

Alcyonarian corals (Octocorallia) living in shallow tropical seas produce spicules of high-Mg calcite with ˜13 mol% MgCO3. We cultured the tropical alcyonarian coral Rhythisma fulvum in experiments varying temperature (19-32 °C) and pH (8.15-8.44). Alkalinity depletion caused by spicule formation systematically varied in the temperature experiments increasing from 19 to 29 °C. Spicules were investigated for their elemental ratios (Mg/Ca, Sr/Ca) using ICP-OES, δ44/40Ca using TIMS, as well as δ18O and δ13C by IRMS. Mg/Ca increased with temperature from 146 to 164 mmol/mol, in good agreement with the range observed for marine inorganic calcite. Mg/Ca increased by 1.0 ± 0.4 mmol/mol/°C, similar to the sensitivity of Miliolid foraminifera. The pH experiments revealed a linear relationship between Mg/Ca and carbonate ion concentration of +0.03 ± 0.02 mmol/mol/μMol. Sr/Ca ranges from 2.5 to 2.9 mmol/mol being in good agreement with other high-Mg calcites. Temperature and pH experiments showed linear dependencies of Sr/Ca matching inorganic calcite trends and pointing to a decoupling of crystal precipitation rate and calcification rate. Ca isotopes range between 0.7‰ and 0.9‰ in good agreement with aragonitic scleractinian corals and calcitic coccoliths. Presumably Ca isotopes are fractionated by a biological mechanism that may be independent of the skeletal mineralogy. We observe no temperature trend, but a significant decrease of δ44/40Ca with increasing pH. This inverse correlation may characterise biologically controlled intracellular calcification. Oxygen isotope ratios are higher than expected for isotopic equilibrium with a temperature sensitivity of -0.15 ± 0.03‰/°C. Carbon isotope ratios are significantly lower than expected for equilibrium and positively correlated with temperature with a slope of 0.20 ± 0.04‰/°C. Many of our observations on trace element incorporation in R. fulvum may be explained by inorganic processes during crystal

Superconducting critical fields of alkali and alkaline-earth intercalates of MoS2

NASA Technical Reports Server (NTRS)

Woollam, J. A.; Somoano, R. B.

1976-01-01

Results are reported for measurements of the critical-field anisotropy and temperature dependence of group-VIB semiconductor MoS2 intercalated with the alkali and alkaline-earth metals Na, K, Rb, Cs, and Sr. The temperature dependences are compared with present theories on the relation between critical field and transition temperature in the clean and dirty limits over the reduced-temperature range from 1 to 0.1. The critical-field anisotropy data are compared with predictions based on coupled-layers and thin-film ('independent-layers') models. It is found that the critical-field boundaries are steep in all cases, that the fields are greater than theoretical predictions at low temperatures, and that an unusual positive curvature in the temperature dependence appears which may be related to the high anisotropy of the layer structure. The results show that materials with the largest ionic intercalate atom diameters and hexagonal structures (K, Rb, and Cs compounds) have the highest critical temperatures, critical fields, and critical-boundary slopes; the critical fields of these materials are observed to exceed the paramagnetic limiting fields.

Chelating resin immobilizing carboxymethylated polyethyleneimine for selective solid-phase extraction of trace elements: Effect of the molecular weight of polyethyleneimine and its carboxymethylation rate.

PubMed

Kagaya, Shigehiro; Kajiwara, Takehiro; Gemmei-Ide, Makoto; Kamichatani, Waka; Inoue, Yoshinori

2016-01-15

The effect of the molecular weight of polyethyleneimine (PEI), defined as a compound having two or more ethyleneamine units, and of its carboxymethylation rate (CM/N), represented by the ratio of ion-exchange capacity to the amount of N on the resin, on the selective solid-phase extraction ability of the chelating resin immobilizing carboxymethylated (CM) PEI was investigated. The chelating resins (24 types) were prepared by immobilization of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, PEI300 (MW=ca. 300), and PEI600 (MW=ca. 600) on methacrylate resins, followed by carboxymethylation with various amounts of sodium monochloroacetate. When resins with approximately the same CM/N ratio (0.242-0.271) were used, the recovery of Cd, Co, Cu, Fe, Ni, Pb, Ti, Zn, and alkaline earth elements increased with increasing the molecular weight of PEIs under acidic and weakly acidic conditions; however, the extraction behavior of Mo and V was only slightly affected. This was probably due to the increase in N content of the resin, resulting in an increase in carboxylic acid groups; the difference in the molecular weight of PEIs immobilized on the resin exerts an insignificant influence on the selective extraction ability. The CM/N ratio considerably affected the extraction behavior for various elements. Under acidic and neutral conditions, the recovery of Cd, Co, Cu, Fe, Ni, Pb, Ti, and Zn increased with increasing CM/N values. However, under these conditions, the recovery of alkaline earth elements was considerably low when a resin with low CM/N ratio was used. This is presumably attributed to the different stability constants of the complexes of these elements with aminocarboxylic acids and amines, and to the electrostatic repulsion between the elements and the protonated amino groups in the CM-PEI. The recovery of Mo and V decreased or varied with increasing CM/N values, suggesting that the extraction of these elements occurred mainly

Catalyst for elemental sulfur recovery process

DOEpatents

Flytzani-Stephanopoulos, Maria; Liu, Wei

1995-01-01

A catalytic reduction process for the direct recovery of elemental sulfur from various SO.sub.2 -containing industrial gas streams. The catalytic process provides high activity and selectivity, as well as stability in the reaction atmosphere, for the reduction of SO.sub.2 to elemental sulfur product with carbon monoxide or other reducing gases. The reaction of sulfur dioxide and reducing gas takes place over a metal oxide composite catalyst having one of the following empirical formulas: [(OF.sub.2).sub.1-n (RO.sub.1)n].sub.1-k M.sub.k, [(FO.sub.2).sub.1-n (RO.sub.1.5).sub.n ].sub.1-k M.sub.k, or [Ln.sub.x Zr.sub.1-x O.sub.2-0.5x ].sub.1-k M.sub.k wherein FO.sub.2 is a fluorite-type oxide; RO represents an alkaline earth oxide; RO.sub.1.5 is a Group IIIB or rare earth oxide; Ln is a rare earth element having an atomic number from 57 to 65 or mixtures thereof; M is a transition metal or a mixture of transition metals; n is a number having a value from 0.0 to 0.35; k is a number having a value from 0.0 to about 0.5; and x is a number having a value from about 0.45 to about 0.55.

Concentrations of Elements in Sediments and Selective Fractions of Sediments, and in Natural Waters in Contact with Sediments from Lake Roosevelt, Washington, September 2004

USGS Publications Warehouse

Paulson, Anthony J.; Wagner, Richard J.; Sanzolone, Richard F.; Cox, Steven E.

2006-01-01

Twenty-eight composite and replicate sediment samples from 8 Lake Roosevelt sites were collected and analyzed for 10 alkali and alkaline earth elements, 2 non-metals, 20 metals, and 4 lanthanide and actinide elements. All elements were detected in all sediment samples except for silver (95 percent of the elements detected for 1,008 analyses), which was detected only in 4 samples. Sequential selective extraction procedures were performed on single composite samples from the eight sites. The percentage of detections for the 31 elements analyzed ranged from 76 percent for the first extraction fraction using a weak extractant to 93 percent for the four-acid dissolution of the sediments remaining after the third sequential selective extraction. Water samples in various degrees of contact with the sediment were analyzed for 10 alkali and alkaline earth elements, 5 non-metals, 25 metals, and 16 lanthanide and actinide elements. The filtered water samples included 10 samples from the reservoir water column at 8 sites, 32 samples of porewater, 55 samples from reservoir water overlying sediments in 8 cores from the site incubated in a field laboratory, and 24 water samples that were filtered after being tumbled with sediments from 8 sites. Overall, the concentrations of only 37 percent of the 6,776 analyses of the 121 water samples were greater than the reporting limit. Selenium, bismuth, chromium, niobium, silver, and zirconium were not detected in any water samples. The percentage of concentrations for the water samples that were above the reporting limit ranged from 14 percent for the lanthanide and actinide elements to 77 percent for the alkali and alkaline earth elements. Concentrations were greater than reporting limits in only 23 percent of the analyses of reservoir water and 29 percent of the analyses of reservoir water overlying incubation cores. In contrast, 47 and 48 percent of the concentrations of porewater and water samples tumbled with sediments, respectively

Effect of the addition of low rare earth elements (lanthanum, neodymium, cerium) on the biodegradation and biocompatibility of magnesium.

PubMed

Willbold, Elmar; Gu, Xuenan; Albert, Devon; Kalla, Katharina; Bobe, Katharina; Brauneis, Maria; Janning, Carla; Nellesen, Jens; Czayka, Wolfgang; Tillmann, Wolfgang; Zheng, Yufeng; Witte, Frank

2015-01-01

Rare earth elements are promising alloying element candidates for magnesium alloys used as biodegradable devices in biomedical applications. Rare earth elements have significant effects on the high temperature strength as well as the creep resistance of alloys and they improve magnesium corrosion resistance. We focused on lanthanum, neodymium and cerium to produce magnesium alloys with commonly used rare earth element concentrations. We showed that low concentrations of rare earth elements do not promote bone growth inside a 750 μm broad area around the implant. However, increased bone growth was observed at a greater distance from the degrading alloys. Clinically and histologically, the alloys and their corrosion products caused no systematic or local cytotoxicological effects. Using microtomography and in vitro experiments, we could show that the magnesium-rare earth element alloys showed low corrosion rates, both in in vitro and in vivo. The lanthanum- and cerium-containing alloys degraded at comparable rates, whereas the neodymium-containing alloy showed the lowest corrosion rates. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The Marine Geochemistry of the Rare Earth Elements

DTIC Science & Technology

1983-09-01

C3): 2045-2056. BACON, M.P., P.G. BREWER, D.W. SPENCER, T.W. MURRAY & T. GODDARD (1980). Lead - 210 , polonium - 210 , manganese and iron in the Cariaco...191 La and Pr 197 Ce: its oxidation and reduction 197 Eu 207 4.5. Conclusions 210 CHAPTER 5. Behaviour of the Rare Earth Elements in anoxic waters of...seawater and algal food . When the radioactive particles were no longer available, the accumulated radioactivity of the zooplankters was rapidly lost

Rare earth element abundances in presolar SiC

NASA Astrophysics Data System (ADS)

Ireland, T. R.; Ávila, J. N.; Lugaro, M.; Cristallo, S.; Holden, P.; Lanc, P.; Nittler, L.; Alexander, C. M. O'D.; Gyngard, F.; Amari, S.

2018-01-01

Individual isotope abundances of Ba, lanthanides of the rare earth element (REE) group, and Hf have been determined in bulk samples of fine-grained silicon carbide (SiC) from the Murchison CM2 chondrite. The analytical protocol involved secondary ion mass spectrometry with combined high mass resolution and energy filtering to exclude REE oxide isobars and Si-C-O clusters from the peaks of interest. Relative sensitivity factors were determined through analysis of NIST SRM reference glasses (610 and 612) as well as a trace-element enriched SiC ceramic. When normalised to chondrite abundances, the presolar SiC REE pattern shows significant deficits at Eu and Yb, which are the most volatile of the REE. The pattern is very similar to that observed for Group III refractory inclusions. The SiC abundances were also normalised to s-process model predictions for the envelope compositions of low-mass (1.5-3 M⊙) AGB stars with close-to-solar metallicities (Z = 0.014 and 0.02). The overall trace element abundances (excluding Eu and Yb) appear consistent with the predicted s-process patterns. The depletions of Eu and Yb suggest that these elements remained in the gas phase during the condensation of SiC. The lack of depletion in some other moderately refractory elements (like Ba), and the presence of volatile elements (e.g. Xe) indicates that these elements were incorporated into SiC by other mechanisms, most likely ion implantation.

Volatile Element Behavior During Melting and Vaporisation on Earth and Protoplanets.

NASA Astrophysics Data System (ADS)

Wood, B. J.; Norris, C. A.

2017-12-01

During accretion the Earth and many of the smaller bodies which were added to it, underwent periods of partial melting, vaporisation and re-condensation. This resulted in patterns of volatile element depletion relative to CI chondrite which are difficult to interpret. The behavior of moderately volatile elements (Pb, Cd, Zn,Cu, In,Tl etc) during these melting, vaporisation and condensation processes is usually approximated by the temperature of condensation from a gas of solar composition. Thus, Tl and In have low condensation temperatures and are regarded as the most volatile of this group. In order to test this volatility approximation we have studied the vaporisation behavior of 13 elements (Ag,Bi,Cd,Cr,Cu,Ga,Ge,In,Pb,Sb,Sn,Tl,Zn) from molten basalt at 1 atm pressure and oxygen fugacities between Ni-NiO and 2 log units below Fe-FeO. The relative volatilities of the elements turn out to be only weakly correlated with condensation temperature, indicating that the latter is a poor proxy for volatility on molten bodies. Cu, Zn and In for example all have similar volatility in the oxygen fugacity range of concern, despite the condensation temperature of Cu (1037K at 10-4bar) being 500K greater than that of In. The oxygen fugacity dependence of volatility indicates that the volatile species are, for all elements more reduced than the melt species. We addressed the differences between condensation temperature and relative volatility in 2 steps. Firstly we used metal-silicate partitioning experiments to estimate the activity coefficients of the trace element oxides in silicate melts. We then used available thermodynamic data to compute the vapor pressures of the stable species of these 13 elements over the silicate melt at oxygen fugacities ranging from Ni-NiO to about 6 log units below Fe-FeO, which approximates the solar gas. Thus we find that presence of Cl and S in the solar gas and the stable Cl and S species of In,Tl Ga Ge Cd and Sn are important contributing

Intrinsically modified thermoelectric performance of alkaline-earth isovalently substituted [Bi2AE2O4][CoO2]y single crystals

NASA Astrophysics Data System (ADS)

Sun, N.; Dong, S. T.; Zhang, B. B.; Chen, Y. B.; Zhou, J.; Zhang, S. T.; Gu, Z. B.; Yao, S. H.; Chen, Y. F.

2013-07-01

Alkaline-earth elements isovalently substituted into a [Bi2AE2O4][CoO2]y (AE2 = Ca2, Sr2, and CaSr) single crystal with a layered structure were grown by the optical floating zone method. Structural characterization by X-ray diffraction and electron microscopy showed that the layers were oriented perpendicular to the c-axis, as well as the growth of direction was parallel to the ab-plane. The thermoelectric properties, including the Seebeck effect, electrical conductivity and thermal conductivity were investigated. The results of the thermoelectric measurements showed that the full substitution of Ca for Sr in [Bi2Sr2-xCaxO4][CoO2]y has the best overall thermoelectric performance. Compared with the other two cases studied, the full Ca substituted crystal [Bi2Ca2O4][CoO2]y exhibits both reduced resistivity and thermal conductivity, but not a reduced Seebeck coefficient. The enhanced thermoelectric property in [Bi2Ca2O4][CoO2]y is mainly due to lower structural symmetry, which is confirmed by electron microscopy characterization. This work demonstrates that even isovalently substitution can play a crucial role in the thermoelectric effect of layered cobalt oxides.

Melting curve of compressed barium carbonate from in situ ionic conductivity measurements: Implications for the melting behavior of alkaline earth carbonates in Earth's deep carbon cycle

NASA Astrophysics Data System (ADS)

Dong, J.; Li, J.; Zhu, F.; Li, Z.; Farawi, R.

2017-12-01

The whereabouts of subducted carbonates place a major constraint on the Earth's deep carbon cycle, but the fraction of carbon retained in the slab and transported into the deep mantle, compared to that released from the slab and recycled to the surface, is still under debate. Knowledge of the stability of carbonated mantle rocks is pivotal for assessing the ability of slabs to carry carbonates into the deep mantle. Determination and systematic comparison of the melting curves of alkali and alkaline earth carbonates at high pressure can help construct thermodynamic models to predict the melting behavior of complex carbonated mantle rocks. Among alkaline earth carbonates, the melting behavior of barium carbonate (BaCO3) has not been adequately understood. The reported melting point of BaCO3at 1 bar differ by nearly 800 °C and constraints on the melting curve of BaCO3 at high pressure are not available. In this study, the melting temperatures of BaCO3 were determined up to 11 GPa from in situ ionic conductivity measurements using the multi-anvil apparatus at the University of Michigan. The solid-liquid boundary at high pressure was detected on the basis of a steep rise in conductivity through the sample upon melting. The melting point of BaCO3 was found to drop from 1797 °C at 3.3 GPa to 1600 °C at 5.5 GPa and then rise with pressure to 2180 °C at 11 GPa. The observed melting depression point at 5.5 GPa corresponds to the phase transition of BaCO3 from the aragonite structure (Pmcn) to post-aragonite structure (Pmmn) at 6.3 GPa, 877 °C and 8.0 GPa, 727 °C, determined from synchrotron X-ray diffraction measurements using laser-heated DAC experiments at the Advanced Photon Source, Argonne National Laboratory. These results are also compared with ex situ falling marker experiments, and the three methods together place tight constraints on the melting curve of BaCO3 and elucidates the effect of structural phase transitions on its melting behavior.

Rare earth element content of thermal fluids from Surprise Valley, California

DOE Data Explorer

Andrew Fowler

2015-09-23

Rare earth element measurements for thermal fluids from Surprise Valley, California. Samples were collected in acid washed HDPE bottles and acidified with concentrated trace element clean (Fisher Scientific) nitric acid. Samples were pre-concentratated by a factor of approximately 10 using chelating resin with and IDA functional group and measured on magnetic sector ICP-MS. Samples include Seyferth Hot Springs, Surprise Valley Resort Mineral Well, Leonard's Hot Spring, and Lake City Mud Volcano Boiling Spring.

[Leaching of Rare Earth Elements from Coal Ashes Using Acidophilic Chemolithotrophic Microbial Communities].

PubMed

Muravyov, M I; Bulaev, A G; Melamud, V S; Kondrat'eva, T F

2015-01-01

A method for leaching rare earth elements from coal ash in the presence of elemental sulfur using communities of acidophilic chemolithotrophic microorganisms was proposed. The optimal parameters determined for rare element leaching in reactors were as follows: temperature, 45 degrees C; initial pH, 2.0; pulp density, 10%; and the coal ash to elemental sulfur ratio, 10 : 1. After ten days of leaching, 52.0, 52.6, and 59.5% of scandium, yttrium, and lanthanum, respectively, were recovered.

2nd International Symposium on Fundamental Aspects of Rare-earth Elements Mining and Separation and Modern Materials Engineering (REES-2015)

NASA Astrophysics Data System (ADS)

Tavadyan, Levon, Prof; Sachkov, Viktor, Prof; Godymchuk, Anna, Dr.; Bogdan, Anna

2016-01-01

The 2nd International Symposium «Fundamental Aspects of Rare-earth Elements Mining and Separation and Modern Materials Engineering» (REES2015) was jointly organized by Tomsk State University (Russia), National Academy of Science (Armenia), Shenyang Polytechnic University (China), Moscow Institute of Physics and Engineering (Russia), Siberian Physical-technical Institute (Russia), and Tomsk Polytechnic University (Russia) in September, 7-15, 2015, Belokuriha, Russia. The Symposium provided a high quality of presentations and gathered engineers, scientists, academicians, and young researchers working in the field of rare and rare earth elements mining, modification, separation, elaboration and application, in order to facilitate aggregation and sharing interests and results for a better collaboration and activity visibility. The goal of the REES2015 was to bring researchers and practitioners together to share the latest knowledge on rare and rare earth elements technologies. The Symposium was aimed at presenting new trends in rare and rare earth elements mining, research and separation and recent achievements in advanced materials elaboration and developments for different purposes, as well as strengthening the already existing contacts between manufactures, highly-qualified specialists and young scientists. The topics of the REES2015 were: (1) Problems of extraction and separation of rare and rare earth elements; (2) Methods and approaches to the separation and isolation of rare and rare earth elements with ultra-high purity; (3) Industrial technologies of production and separation of rare and rare earth elements; (4) Economic aspects in technology of rare and rare earth elements; and (5) Rare and rare earth based materials (application in metallurgy, catalysis, medicine, optoelectronics, etc.). We want to thank the Organizing Committee, the Universities and Sponsors supporting the Symposium, and everyone who contributed to the organization of the event and to

Selective liquid chromatographic separation of yttrium from heavier rare earth elements using acetic acid as a novel eluent.

PubMed

Kifle, Dejene; Wibetoe, Grethe

2013-09-13

One of the major difficulties in the rare earth elements separation is purification of yttrium from heavy rare earth elements. Thus, an HPLC method using acetic acid as novel eluent was explored for selective separation of yttrium form the heavy rare earth elements. When acetic acid is used as a mobile phase yttrium eluted with the lighter lanthanides. This is contrary to its relative position amongst heavier lanthanides when eluents commonly used for separation of rare earth elements were employed. The shift in elution position of yttrium with acetic acid as eluent may reflect a relatively lower stability constant of the yttrium-AcOH complex (in the same order as for the lighter lanthanides) compared to the corresponding AcOH complexes with heavy lanthanides, enabling selective separation of yttrium from the latter. The method was successfully used for selective separation of yttrium in mixed rare earth sample containing about 80% of yttrium and about 20% of heavy rare earth oxides. Thus, the use of AcOH as eluent is an effective approach for separating and determining the trace amounts of heavy rare earth elements in large amounts of yttrium matrix. Separation was performed on C18 column by running appropriate elution programs. The effluent from the column was monitored with diode array detector at absorbance wavelength of 658nm after post column derivatization with Arsenazo III. Copyright © 2013 Elsevier B.V. All rights reserved.

Unraveling Recrystallization Mechanisms Governing Texture Development from Rare Earth Element Additions to Magnesium

NASA Astrophysics Data System (ADS)

Imandoust, Aidin

The origin of texture components associated with rare-earth (RE) element additions in wrought magnesium (Mg) alloys is a long-standing problem in magnesium technology. The objective of this research is to identify the mechanisms accountable for rare-earth texture during dynamic recrystallization (DRX). Towards this end, we designed binary Mg-Cerium and Mg-Gadolinium alloys along with complex alloy compositions containing zinc, yttrium and Mischmetal. Binary alloys along with pure Mg were designed to individually investigate their effects on texture evolutions, while complex compositions are designed to develop randomized texture, and be used in automotive and aerospace applications. We selected indirect extrusion to thermo-mechanically process our materials. Different extrusion ratios and speeds were designed to produce partially and fully recrystallized microstructures, allowing us to analyze DRX from its early stages to completion. X-ray diffraction, electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) were used to conduct microstructure and texture analyses. Our analyses revealed that rare-earth elements in zinc-containing magnesium alloys promote discontinuous dynamic recrystallization at the grain boundaries. During nucleation, the effect of rare earth elements on orientation selection was explained by the concomitant actions of multiple Taylor axes in the same grain. Isotropic grain growth was observed due to rare earth elements segregating to grain boundaries, which lead to texture randomization. The nucleation in binary Mg-RE alloys took place by continuous formation of necklace structures. Stochastic relaxation of basal and non-basal dislocations into low-angle grain boundaries produced chains of embryos with nearly random orientations. Schmid factor analysis showed a lower net activation of dislocations in RE textured grains compared to ones on the other side of the stereographic triangle. Lower dislocation densities within

Characterization and quantification of biochar alkalinity.

PubMed

Fidel, Rivka B; Laird, David A; Thompson, Michael L; Lawrinenko, Michael

2017-01-01

Lack of knowledge regarding the nature of biochar alkalis has hindered understanding of pH-sensitive biochar-soil interactions. Here we investigate the nature of biochar alkalinity and present a cohesive suite of methods for its quantification. Biochars produced from cellulose, corn stover and wood feedstocks had significant low-pK a organic structural (0.03-0.34 meq g -1 ), other organic (0-0.92 meq g -1 ), carbonate (0.02-1.5 meq g -1 ), and other inorganic (0-0.26 meq g -1 ) alkalinities. All four categories of biochar alkalinity contributed to total biochar alkalinity and are therefore relevant to pH-sensitive soil processes. Total biochar alkalinity was strongly correlated with base cation concentration, but biochar alkalinity was not a simple function of elemental composition, soluble ash, fixed carbon, or volatile matter content. More research is needed to characterize soluble biochar alkalis other than carbonates and to establish predictive relationships among biochar production parameters and the composition of biochar alkalis. Copyright © 2016 Elsevier Ltd. All rights reserved.

The effect of diagenesis and fluid migration on rare earth element distribution in pore fluids of the northern Cascadia accretionary margin

USGS Publications Warehouse

Kim, Ji-Hoon; Torres, Marta E.; Haley, Brian A.; Kastner, Miriam; Pohlman, John W.; Riedel, Michael; Lee, Young-Joo

2012-01-01

Analytical challenges in obtaining high quality measurements of rare earth elements (REEs) from small pore fluid volumes have limited the application of REEs as deep fluid geochemical tracers. Using a recently developed analytical technique, we analyzed REEs from pore fluids collected from Sites U1325 and U1329, drilled on the northern Cascadia margin during the Integrated Ocean Drilling Program (IODP) Expedition 311, to investigate the REE behavior during diagenesis and their utility as tracers of deep fluid migration. These sites were selected because they represent contrasting settings on an accretionary margin: a ponded basin at the toe of the margin, and the landward Tofino Basin near the shelf's edge. REE concentrations of pore fluid in the methanogenic zone at Sites U1325 and U1329 correlate positively with concentrations of dissolved organic carbon (DOC) and alkalinity. Fractionations across the REE series are driven by preferential complexation of the heavy REEs. Simultaneous enrichment of diagenetic indicators (DOC and alkalinity) and of REEs (in particular the heavy elements Ho to Lu), suggests that the heavy REEs are released during particulate organic carbon (POC) degradation and are subsequently chelated by DOC. REE concentrations are greater at Site U1325, a site where shorter residence times of POC in sulfate-bearing redox zones may enhance REE burial efficiency within sulfidic and methanogenic sediment zones where REE release ensues. Cross-plots of La concentrations versus Cl, Li and Sr delineate a distinct field for the deep fluids (z > 75 mbsf) at Site U1329, and indicate the presence of a fluid not observed at the other sites drilled on the Cascadia margin. Changes in REE patterns, the presence of a positive Eu anomaly, and other available geochemical data for this site suggest a complex hydrology and possible interaction with the igneous Crescent Terrane, located east of the drilled transect.

Levels of major and trace elements, including rare earth elements, and ²³⁸U in Croatian tap waters.

PubMed

Fiket, Željka; Rožmarić, Martina; Krmpotić, Matea; Benedik, Ljudmila

2015-05-01

Concentrations of 46 elements, including major, trace, and rare earth elements, and (238)U in Croatian tap waters were investigated. Selected sampling locations include tap waters from various hydrogeological regions, i.e., different types of aquifers, providing insight into the range of concentrations of studied elements and (238)U activity concentrations in Croatian tap waters. Obtained concentrations were compared with the Croatian maximum contaminant levels for trace elements in water intended for human consumption, as well as WHO and EPA drinking water standards. Concentrations in all analyzed tap waters were found in accordance with Croatian regulations, except tap water from Šibenik in which manganese in concentration above maximum permissible concentration (MPC) was measured. Furthermore, in tap water from Osijek, levels of arsenic exceeded the WHO guidelines and EPA regulations. In general, investigated tap waters were found to vary considerably in concentrations of studied elements, including (238)U activity concentrations. Causes of variability were further explored using statistical methods. Composition of studied tap waters was found to be predominately influenced by hydrogeological characteristics of the aquifer, at regional and local level, the existing redox conditions, and the household plumbing system. Rare earth element data, including abundances and fractionation patterns, complemented the characterization and facilitated the interpretation of factors affecting the composition of the analyzed tap waters.

Experimental Parameters Affecting Stripping of Rare Earth Elements from Loaded Sorptive Media in Simulated Geothermal Brines

DOE Data Explorer

Dean Stull

2016-05-24

Experimental results from several studies exploring the impact of pH and acid volume on the stripping of rare earth elements (REEs) loaded onto ligand-based media via an active column. The REEs in this experiment were loaded onto the media through exposure to a simulated geothermal brine with known mineral concentrations. The data include the experiment results, rare earth element concentrations, and the experimental parameters varied.

Structural Responses and Finite Element Modeling of Hakka Tulou Rammed Earth Structures

NASA Astrophysics Data System (ADS)

Sranislawski, Daniel

Hakka Tulous are rammed earth structures that have survived the effects of aging and natural elements upwards of even over a thousand years. These structures have housed the Hakka people of the Fujian Province, China in natural yet modern housing that has provided benefits over newer building materials. The key building material, rammed earth, which is used for the walls of the Hakka Tulou structures, has provided structural stability along with thermal comfort to the respective inhabitants of the Hakka Tulous. Through material testing and analysis this study has examined how the Tulou structures have maintained their structural stability while also providing thermal comfort. Reports of self healing cracks in the rammed earth walls were also analyzed for their validity in this study. The study has found that although the story of the self healing crack cannot be validated, there is reason to believe that with the existence of lime, some type of autogenous healing could occur on a small scale. The study has also found, through the use of nondestructive testing, that both the internal wooden systems (flooring, roof, and column support) and the rammed earth walls, are still structurally sound. Also, rammed earth's high thermal mass along with the use of sufficient shading has allowed for a delay release of heat energy from the walls of the Tulous, thus providing thermal comfort that can be felt during both night and day temperatures. The Hakka Tulou structures have been found to resist destruction from natural disasters such as strong earthquakes even when more modern construction has not. Through finite element modeling, this study has shown that the high volume of rammed earth used in the construction of the Hakka Tulous helps dissipate lateral force energy into much lower stresses for the rammed earth wall. This absorption of lateral force energy allows the rammed earth structures to survive even the strongest of earthquakes experienced in the region. The Hakka

Rare Earth elements in individual minerals in Shergottites

NASA Technical Reports Server (NTRS)

Wadhwa, Meenakshi; Crozaz, Ghislaine

1993-01-01

Shergottites (i.e., Shergotty, Zagami, EETA79001, ALHA77005, and LEW88516) are an important set of achondrites because they comprise the majority of the SNC group of meteorites (nine, in total, known to us), which are likely to be samples of the planet Mars. Study of these meteorites may therefore provide valuable information about petrogenetic processes on a large planetary body other than Earth. Rare earth element (REE) distributions between various mineral phases were found to be useful in geochemically modeling the petrogenesis of various rock types (terrestrial and meteoritic). However, with the exception of a few ion microprobe studies and analyses of mineral separates, there has previously not been any comprehensive effort to characterize and directly compare REE in individual minerals in each of the five known shergottites. Ion microprobe analyses were made on thin sections of each of the shergottites. Minerals analyzed were pyroxenes (pigeonite and augite), maskelynite, and whitlockite. The REE concentrations in each mineral type in each shergottite is given.

Analysis of Rare Earth Elements in Uranium Using Handheld Laser-Induced Breakdown Spectroscopy (HH LIBS)

DOE PAGES

Manard, Benjamin T.; Wylie, E. Miller; Willson, Stephen P.

2018-05-22

In this paper, a portable handheld laser-induced breakdown spectroscopy (HH LIBS) instrument was evaluated as a rapid method to qualitatively analyze rare earth elements in a uranium oxide matrix. This research is motivated by the need for development of a method to perform rapid, at-line chemical analysis in a nuclear facility, particularly to provide a rapid first pass analysis to determine if additional actions or measurements are warranted. This will result in the minimization of handling and transport of radiological and nuclear material and subsequent exposure to their associated hazards. In this work, rare earth elements (Eu, Nd, and Yb)more » were quantitatively spiked into a uranium oxide powder and analyzed by the HH LIBS instrumentation. This method demonstrates the ability to rapidly identify elemental constituents in sub-percent levels in a uranium matrix. Preliminary limits of detection (LODs) were determined with values on the order of hundredths of a percent. Validity of this methodology was explored by employing a National Institute of Standards and Technology (NIST) standard reference materials (SRM) 610 and 612 (Trace Elements in Glass). Finally, it was determined that the HH LIBS method was able to clearly discern the rare earths elements of interest in the glass or uranium matrices.« less

Analysis of Rare Earth Elements in Uranium Using Handheld Laser-Induced Breakdown Spectroscopy (HH LIBS)

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

Manard, Benjamin T.; Wylie, E. Miller; Willson, Stephen P.

In this paper, a portable handheld laser-induced breakdown spectroscopy (HH LIBS) instrument was evaluated as a rapid method to qualitatively analyze rare earth elements in a uranium oxide matrix. This research is motivated by the need for development of a method to perform rapid, at-line chemical analysis in a nuclear facility, particularly to provide a rapid first pass analysis to determine if additional actions or measurements are warranted. This will result in the minimization of handling and transport of radiological and nuclear material and subsequent exposure to their associated hazards. In this work, rare earth elements (Eu, Nd, and Yb)more » were quantitatively spiked into a uranium oxide powder and analyzed by the HH LIBS instrumentation. This method demonstrates the ability to rapidly identify elemental constituents in sub-percent levels in a uranium matrix. Preliminary limits of detection (LODs) were determined with values on the order of hundredths of a percent. Validity of this methodology was explored by employing a National Institute of Standards and Technology (NIST) standard reference materials (SRM) 610 and 612 (Trace Elements in Glass). Finally, it was determined that the HH LIBS method was able to clearly discern the rare earths elements of interest in the glass or uranium matrices.« less

Analysis of Rare Earth Elements in Uranium Using Handheld Laser-Induced Breakdown Spectroscopy (HH LIBS).

PubMed

Manard, Benjamin T; Wylie, E Miller; Willson, Stephen P

2018-01-01

A portable handheld laser-induced breakdown spectroscopy (HH LIBS) instrument was evaluated as a rapid method to qualitatively analyze rare earth elements in a uranium oxide matrix. This research is motivated by the need for development of a method to perform rapid, at-line chemical analysis in a nuclear facility, particularly to provide a rapid first pass analysis to determine if additional actions or measurements are warranted. This will result in the minimization of handling and transport of radiological and nuclear material and subsequent exposure to their associated hazards. In this work, rare earth elements (Eu, Nd, and Yb) were quantitatively spiked into a uranium oxide powder and analyzed by the HH LIBS instrumentation. This method demonstrates the ability to rapidly identify elemental constituents in sub-percent levels in a uranium matrix. Preliminary limits of detection (LODs) were determined with values on the order of hundredths of a percent. Validity of this methodology was explored by employing a National Institute of Standards and Technology (NIST) standard reference materials (SRM) 610 and 612 (Trace Elements in Glass). It was determined that the HH LIBS method was able to clearly discern the rare earths elements of interest in the glass or uranium matrices.

Spectral analysis of rare earth elements using laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Martin, Madhavi Z.; Fox, Robert V.; Miziolek, Andrzej W.; DeLucia, Frank C.; André, Nicolas

2015-06-01

There is growing interest in rapid analysis of rare earth elements (REEs) both due to the need to find new natural sources to satisfy increased demand in their use in various electronic devices, as well as the fact that they are used to estimate actinide masses for nuclear safeguards and nonproliferation. Laser-Induced Breakdown Spectroscopy (LIBS) appears to be a particularly well-suited spectroscopy-based technology to rapidly and accurately analyze the REEs in various matrices at low concentration levels (parts-per-million). Although LIBS spectra of REEs have been reported for a number of years, further work is still necessary in order to be able to quantify the concentrations of various REEs in realworld complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare earth elements of commercial interest are found in the following three matrix groups: 1) raw ores and unrefined materials, 2) as components in refined products such as magnets, lighting phosphors, consumer electronics (which are mostly magnets and phosphors), catalysts, batteries, etc., and 3) waste/recyclable materials (aka e-waste). LIBS spectra for REEs such as Gd, Nd, and Sm found in rare earth magnets are presented.

Spectral Analysis of Rare Earth Elements using Laser-Induced Breakdown Spectroscopy

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

Martin, Madhavi Z; Fox, Dr. Richard V; Miziolek, Andrzej W

2015-01-01

There is growing interest in rapid analysis of rare earth elements (REEs) both due to the need to find new natural sources to satisfy increased demand in their use in various electronic devices, as well as the fact that they are used to estimate actinide masses for nuclear safeguards and nonproliferation. Laser-Induced Breakdown Spectroscopy (LIBS) appears to be a particularly well-suited spectroscopy-based technology to rapidly and accurately analyze the REEs in various matrices at low concentration levels (parts-per-million). Although LIBS spectra of REEs have been reported for a number of years, further work is still necessary in order to bemore » able to quantify the concentrations of various REEs in real-world complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare earth elements of commercial interest are found in the following three matrix groups: 1) raw ores and unrefined materials, 2) as components in refined products such as magnets, lighting phosphors, consumer electronics (which are mostly magnets and phosphors), catalysts, batteries, etc., and 3) waste/recyclable materials (aka e-waste). LIBS spectra for REEs such as Gd, Nd, and Sm found in rare earth magnets are presented.« less

Spectral Analysis of Rare Earth Elements using Laser-Induced Breakdown Spectroscopy

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

Martin, Madhavi Z; Fox, Dr. Richard V; Miziolek, Andrzej W

2015-01-01

There is growing interest in rapid analysis of rare earth elements (REEs) both due to the need to find new natural sources to satisfy increased demand in their use in various electronic devices, as well as the fact that they are used to estimate actinide masses for nuclear safeguards and nonproliferation. Laser-Induced Breakdown Spectroscopy (LIBS) appears to be a particularly well-suited spectroscopy-based technology to rapidly and accurately analyze the REEs in various matrices at low concentration levels (parts-per-million). Although LIBS spectra of REEs have been reported for a number of years, further work is still necessary in order to bemore » able to quantify the concentrations of various REEs in realworld complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare earth elements of commercial interest are found in the following three matrix groups: 1) raw ores and unrefined materials, 2) as components in refined products such as magnets, lighting phosphors, consumer electronics (which are mostly magnets and phosphors), catalysts, batteries, etc., and 3) waste/recyclable materials (aka e-waste). LIBS spectra for REEs such as Gd, Nd, and Sm found in rare earth magnets are presented.« less

Spectral Analysis of Rare Earth Elements using Laser-Induced Breakdown Spectroscopy

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

Madhavi Z. Martin; Robert V. Fox; Andrzej W. Miziolek

2001-05-01

There is growing interest in rapid analysis of rare earth elements (REEs) both due to the need to find new natural sources to satisfy increased demand in their use in various electronic devices, as well as the fact that they are used to estimate actinide masses for nuclear safeguards and nonproliferation. Laser-Induced Breakdown Spectroscopy (LIBS) appears to be a particularly well-suited spectroscopy-based technology to rapidly and accurately analyze the REEs in various matrices at low concentration levels (parts-per-million). Although LIBS spectra of REEs have been reported for a number of years, further work is still necessary in order to bemore » able to quantify the concentrations of various REEs in realworld complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare earth elements of commercial interest are found in the following three matrix groups: 1) raw ores and unrefined materials, 2) as components in refined products such as magnets, lighting phosphors, consumer electronics (which are mostly magnets and phosphors), catalysts, batteries, etc., and 3) waste/recyclable materials (aka e-waste). LIBS spectra for REEs such as Gd, Nd, and Sm found in rare earth magnets are presented.« less

Isomorphous Substitution of Rare-Earth Elements in Lacunary Apatite Pb8Na2(PO4)6.

PubMed

Get'man, Evgeni I; Loboda, Stanislav N; Ignatov, Alexey V; Prisedsky, Vadim V; Abdul Jabar, Mohammed A B; Ardanova, Lyudmyla I

2016-03-07

The substitution of rare-earth elements (REEs) for Pb in the lacunary apatite Pb8Na2(PO4)6 with void structural channels was studied by means of powder X-ray diffraction (including the Rietveld refinement), scanning electron microscopy, energy-dispersive X-ray microanalysis, and IR spectroscopy and also measurements of the electrical conductivity. The substitution limits (xmax in Pb8-xLnxNa2(PO4)6Ox/2) at 800 °C were found to decrease with the atomic number of the REE from 1.40 for La to 0.12 for Yb with a rapid drop from light to heavy lanthanides (between Gd and Tb). The REE atoms substitute for Pb predominantly at Pb2 sites of the apatite structure according to the scheme 2Pb(2+) + □ → 2Ln(3+) + O(2-), where □ is a vacancy in the structural channel. The substitution in lacunary apatite produces quite different changes in the structural parameters compared with broadly studied alkaline-earth hydroxyapatites. In spite of the much lower ionic radii of REE than that of Pb(2+), the mean distances ⟨Pb1-O⟩ somewhat increase, whereas the distances ⟨Pb2-Pb2⟩ and ⟨Pb2-O4⟩ do not change considerably with the degree of substitution. This implies control of the substitution by not only spatial and charge accommodation of REE ions but also the availability of a stereochemically active 6s(2) electron pair on Pb(2+). The high-temperature electrical conductivity shows dependence on the degree of substitution with a minimum at x = 0.2 indicative of a possible change of the type of conductivity.

A Kirkwood-Buff derived force field for alkaline earth halide salts

NASA Astrophysics Data System (ADS)

Naleem, Nawavi; Bentenitis, Nikolaos; Smith, Paul E.

2018-06-01

The activity and function of many macromolecules in cellular environments are coupled with the binding of divalent ions such as calcium or magnesium. In principle, computer simulations can be used to understand the molecular level aspects of how many important macromolecules interact with ions. However, most of the force fields currently available often fail to accurately reproduce the properties of divalent ions in aqueous environments. Here we develop classical non-polarizable force fields for the aqueous alkaline earth metal halides (MX2), where M = Mg2+, Ca2+, Sr2+, Ba2+ and X = Cl-, Br-, I-, which can be used in bimolecular simulations and which are compatible with the Simple Point Charge/Extended (SPC/E) water model. The force field parameters are specifically developed to reproduce the experimental Kirkwood-Buff integrals for aqueous solutions and thereby the experimental activity derivatives, partial molar volumes, and excess coordination numbers. This ensures that a reasonable balance between ion-ion, ion-water, and water-water distributions is obtained. However, this requires a scaling of the cation to water oxygen interaction strength in order to accurately reproduce the integrals. The scaling factors developed for chloride salts are successfully transferable to the bromide and iodide salts. Use of these new models leads to reasonable diffusion constants and dielectric decrements. However, the performance of the models decreases with increasing salt concentration (>4m), and simulations of the pure crystals exhibited unstable behavior.

A Kirkwood-Buff derived force field for alkaline earth halide salts.

PubMed

Naleem, Nawavi; Bentenitis, Nikolaos; Smith, Paul E

2018-06-14

The activity and function of many macromolecules in cellular environments are coupled with the binding of divalent ions such as calcium or magnesium. In principle, computer simulations can be used to understand the molecular level aspects of how many important macromolecules interact with ions. However, most of the force fields currently available often fail to accurately reproduce the properties of divalent ions in aqueous environments. Here we develop classical non-polarizable force fields for the aqueous alkaline earth metal halides (MX 2 ), where M = Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ and X = Cl - , Br - , I - , which can be used in bimolecular simulations and which are compatible with the Simple Point Charge/Extended (SPC/E) water model. The force field parameters are specifically developed to reproduce the experimental Kirkwood-Buff integrals for aqueous solutions and thereby the experimental activity derivatives, partial molar volumes, and excess coordination numbers. This ensures that a reasonable balance between ion-ion, ion-water, and water-water distributions is obtained. However, this requires a scaling of the cation to water oxygen interaction strength in order to accurately reproduce the integrals. The scaling factors developed for chloride salts are successfully transferable to the bromide and iodide salts. Use of these new models leads to reasonable diffusion constants and dielectric decrements. However, the performance of the models decreases with increasing salt concentration (>4m), and simulations of the pure crystals exhibited unstable behavior.

Energetics of Amino Acid Synthesis in Alkaline Hydrothermal Environments

NASA Astrophysics Data System (ADS)

Kitadai, Norio

2015-12-01

Alkaline hydrothermal systems have received considerable attention as candidates for the origin and evolution of life on the primitive Earth. Nevertheless, sufficient information has not yet been obtained for the thermodynamic properties of amino acids, which are necessary components for life, at high temperatures and alkaline pH. These properties were estimated using experimental high-temperature volume and heat capacity data reported in the literature for several amino acids, together with correlation algorithms and the revised Helgeson-Kirkham-Flowers (HKF) equations of state. This approach enabled determination of a complete set of the standard molal thermodynamic data and the revised HKF parameters for the 20 protein amino acids in their zwitterionic and ionization states. The obtained dataset was then used to evaluate the energetics of amino acid syntheses from simple inorganic precursors (CO2, H2, NH3 and H2S) in a simulated alkaline hydrothermal system on the Hadean Earth. Results show that mixing between CO2-rich seawater and the H2-rich hydrothermal fluid can produce energetically favorable conditions for amino acid syntheses, particularly in the lower-temperature region of such systems. Together with data related to the pH and temperature dependences of the energetics of amino acid polymerizations presented in earlier reports, these results suggest the following. Hadean alkaline hydrothermal settings, where steep pH and temperature gradients may have existed between cool, slightly acidic Hadean ocean water and hot, alkaline hydrothermal fluids at the vent-ocean interface, may be energetically the most suitable environment for the synthesis and polymerization of amino acids.

Energetics of Amino Acid Synthesis in Alkaline Hydrothermal Environments.

PubMed

Kitadai, Norio

2015-12-01

Alkaline hydrothermal systems have received considerable attention as candidates for the origin and evolution of life on the primitive Earth. Nevertheless, sufficient information has not yet been obtained for the thermodynamic properties of amino acids, which are necessary components for life, at high temperatures and alkaline pH. These properties were estimated using experimental high-temperature volume and heat capacity data reported in the literature for several amino acids, together with correlation algorithms and the revised Helgeson-Kirkham-Flowers (HKF) equations of state. This approach enabled determination of a complete set of the standard molal thermodynamic data and the revised HKF parameters for the 20 protein amino acids in their zwitterionic and ionization states. The obtained dataset was then used to evaluate the energetics of amino acid syntheses from simple inorganic precursors (CO2, H2, NH3 and H2S) in a simulated alkaline hydrothermal system on the Hadean Earth. Results show that mixing between CO2-rich seawater and the H2-rich hydrothermal fluid can produce energetically favorable conditions for amino acid syntheses, particularly in the lower-temperature region of such systems. Together with data related to the pH and temperature dependences of the energetics of amino acid polymerizations presented in earlier reports, these results suggest the following. Hadean alkaline hydrothermal settings, where steep pH and temperature gradients may have existed between cool, slightly acidic Hadean ocean water and hot, alkaline hydrothermal fluids at the vent-ocean interface, may be energetically the most suitable environment for the synthesis and polymerization of amino acids.

Honeycomb-shaped coordination polymers based on the self-assembly of long flexible ligands and alkaline-earth ions

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

Lian, Chen; Liu, Liu; Guo, Xu

2016-01-15

Two novel coordination polymers, namely, [Ca(NCP){sub 2}]{sub ∞} (I) and [Sr(NCP){sub 2}]{sub ∞} (II) were synthesized under hydrothermal conditions based on 2-(4-carboxyphenyl)imidazo(4,5-f)-(1,10)phenanthroline (HNCP) and characterized by elemental analysis, infrared spectrometry, X-ray powder diffraction and single crystal X-ray diffraction. Findings indicate that I and II are isomorphous and isostructural, containing the unit of M(NCP{sup −}){sub 4} (M=Ca(II) and Sr(II)), based on which to assemble into three-dimensional (3D) porous 4-fold interpenetration honeycomb-shaped neutral coordination polymers (CPs). Between the adjacent lamellar structures in I and II, there exist π–π interactions between the pyridine rings belonging to phenanthroline of NCP{sup −} which stabilize themore » frameworks. Both I and II display stronger fluorescence emissions as well as high thermal stability. - Graphical abstract: One-dimensional nanotubular channels with the cross dimension of 37.1959(20)×23.6141(11)Å{sup 2} in the three-dimensional honeycomb-shaped coordination network of II are observed. The topological analysis of II indicates that there exists a typical diamond framework possessing large adamantanoid cages, which containing four cyclohexane-shaped patterns in chair conformations. - Highlights: • Two isomorphous and isostructural coordination polymers based on flexible ligand and two alkaline-earth metal salts have been synthesized and characterized. • Structural analysis indicates that I and II are assembled into 3D porous honeycomb-shaped metal-organic frameworks. • Both I and II display stronger fluorescence emissions and higher thermal stability.« less

A novel approach for acid mine drainage pollution biomonitoring using rare earth elements bioaccumulated in the freshwater clam Corbicula fluminea.

PubMed

Bonnail, Estefanía; Pérez-López, Rafael; Sarmiento, Aguasanta M; Nieto, José Miguel; DelValls, T Ángel

2017-09-15

Lanthanide series have been used as a record of the water-rock interaction and work as a tool for identifying impacts of acid mine drainage (lixiviate residue derived from sulphide oxidation). The application of North-American Shale Composite-normalized rare earth elements patterns to these minority elements allows determining the origin of the contamination. In the current study, geochemical patterns were applied to rare earth elements bioaccumulated in the soft tissue of the freshwater clam Corbicula fluminea after exposure to different acid mine drainage contaminated environments. Results show significant bioaccumulation of rare earth elements in soft tissue of the clam after 14 days of exposure to acid mine drainage contaminated sediment (ΣREE=1.3-8μg/gdw). Furthermore, it was possible to biomonitor different degrees of contamination based on rare earth elements in tissue. The pattern of this type of contamination describes a particular curve characterized by an enrichment in the middle rare earth elements; a homologous pattern (E MREE =0.90) has also been observed when applied NASC normalization in clam tissues. Results of lanthanides found in clams were contrasted with the paucity of toxicity studies, determining risk caused by light rare earth elements in the Odiel River close to the Estuary. The current study purposes the use of clam as an innovative "bio-tool" for the biogeochemical monitoring of pollution inputs that determines the acid mine drainage networks affection. Copyright © 2017 Elsevier B.V. All rights reserved.

Bonding of Alkali-Alkaline Earth Molecules in the Lowest Σ^+ States of Doublet and Quartet Multiplicity

NASA Astrophysics Data System (ADS)

Pototschnig, Johann V.; Hauser, Andreas W.; Ernst, Wolfgang E.

2016-06-01

n the present study the ground state as well as the lowest ^4Σ^+ state were determined for 16 AK-AKE molecules. Multireference configuration interaction calculations were carried out in order to understand the bonding of diatomic alkali-alkaline earth (AK-AKE) molecules. The correlations between molecular properties (disociation energy, bond distances, electric dipole moment) and atomic properties (electronegativity, polarizability) will be discussed. A correlation between the dissociation energy and the dipole moment of the lowest ^4Σ^+ state was observed, while the dipole moment of the lowest ^2Σ^+ state does not show such a simple dependency. In this case an empirical relation could be established. The class of AK-AKE molecules was selected for this investigation due to their possible applications in ultracold molecular physics. J. V. Pototschnig, A. W. Hauser and W. E. Ernst, Phys. Chem. Chem. Phys., 2016,18, 5964-5973

Rare earth elements in river waters

NASA Technical Reports Server (NTRS)

Goldstein, Steven J.; Jacobsen, Stein B.

1988-01-01

To characterize the input to the oceans of rare earth elements (REE) in the dissolved and the suspended loads of rivers, the REE concentrations were measured in samples of Amazon, Indus, Mississippi, Murray-Darling, and Ohio rivers and in samples of smaller rivers that had more distinct drainage basin lithology and water chemistry. It was found that, in the suspended loads of small rivers, the REE pattern was dependent on drainage basin geology, whereas the suspended loads in major rivers had relatively uniform REE patterns and were heavy-REE depleted relative to the North American Shale composite (NASC). The dissolved loads in the five major rivers had marked relative heavy-REE enrichments, relative to the NASC and the suspended material, with the (La/Yb)N ratio of about 0.4 (as compared with the ratio of about 1.9 in suspended loads).

RARE EARTH ELEMENT IMPACTS ON BIOLOGICAL WASTEWATER TREATMENT

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

Fujita, Y.; Barnes, J.; Fox, S.

Increasing demand for rare earth elements (REE) is expected to lead to new development and expansion in industries processing and or recycling REE. For some industrial operators, sending aqueous waste streams to a municipal wastewater treatment plant, or publicly owned treatment works (POTW), may be a cost effective disposal option. However, wastewaters that adversely affect the performance of biological wastewater treatment at the POTW will not be accepted. The objective of our research is to assess the effects of wastewaters that might be generated by new rare earth element (REE) beneficiation or recycling processes on biological wastewater treatment systems. Wemore » have been investigating the impact of yttrium and europium on the biological activity of activated sludge collected from an operating municipal wastewater treatment plant. We have also examined the effect of an organic complexant that is commonly used in REE extraction and separations; similar compounds may be a component of newly developed REE recycling processes. Our preliminary results indicate that in the presence of Eu, respiration rates for the activated sludge decrease relative to the no-Eu controls, at Eu concentrations ranging from <10 to 660 µM. Yttrium appears to inhibit respiration as well, although negative impacts have been observed only at the highest Y amendment level tested (660 µM). The organic complexant appears to have a negative impact on activated sludge activity as well, although results are variable. Ultimately the intent of this research is to help REE industries to develop environmentally friendly and economically sustainable beneficiation and recycling processes.« less

Evaluating rare earth element availability: a case with revolutionary demand from clean technologies.

PubMed

Alonso, Elisa; Sherman, Andrew M; Wallington, Timothy J; Everson, Mark P; Field, Frank R; Roth, Richard; Kirchain, Randolph E

2012-03-20

The future availability of rare earth elements (REEs) is of concern due to monopolistic supply conditions, environmentally unsustainable mining practices, and rapid demand growth. We present an evaluation of potential future demand scenarios for REEs with a focus on the issue of comining. Many assumptions were made to simplify the analysis, but the scenarios identify some key variables that could affect future rare earth markets and market behavior. Increased use of wind energy and electric vehicles are key elements of a more sustainable future. However, since present technologies for electric vehicles and wind turbines rely heavily on dysprosium (Dy) and neodymium (Nd), in rare-earth magnets, future adoption of these technologies may result in large and disproportionate increases in the demand for these two elements. For this study, upper and lower bound usage projections for REE in these applications were developed to evaluate the state of future REE supply availability. In the absence of efficient reuse and recycling or the development of technologies which use lower amounts of Dy and Nd, following a path consistent with stabilization of atmospheric CO(2) at 450 ppm may lead to an increase of more than 700% and 2600% for Nd and Dy, respectively, over the next 25 years if the present REE needs in automotive and wind applications are representative of future needs.

Trace element partitioning in rock forming minerals of co-genetic, subduction-related alkaline and tholeiitic mafic rocks in the Ural Mountains, Russia

NASA Astrophysics Data System (ADS)

Krause, J.; Brügmann, G. E.; Pushkarev, E. V.

2009-04-01

The partitioning of trace elements between rock forming minerals in igneous rocks is largely controlled by physical and chemical parameters e.g. temperature, pressure and chemical composition of the minerals and the coexisting melt. In the present study partition coefficients for REE between hornblende, orthopyroxene, feldspars, apatite and clinopyroxene in a suite of co-genetic alkaline and tholeiitic mafic rocks from the Ural Mountains (Russia) were calculated. The results give insights to the influence of the chemical composition of the parental melt on the partitioning behaviour of the REE. Nepheline-bearing, alkaline melanogabbros (tilaites) are assumed to represent the most fractionated products of the melt that formed the ultramafic cumulates in zoned mafic-ultramafic complexes in the Ural Mountains. Co-genetic with the latter is a suite of olivine gabbros, gabbronorites and hornblende gabbros formed from a tholeiitic parental melt. Negative anomalies for the HFSE along with low Nb and Ta contents and a positive Sr anomaly indicate a subduction related origin of all parental melts. The nepheline gabbros consist predominantly of coarse-grained clinopyroxene phenocrysts in a matrix of fine grained clinopyroxene, olivine, plagioclase, K-feldspar and nepheline with accessory apatite. The tholeiitic gabbros have equigranular to porphyric textures with phenocrysts of olivine, pyroxene and hornblende in a plagioclase rich matrix with olivine hornblende, pyroxene and accessory apatite. Element concentrations of adjacent matrix grains and rims of phenochrysts were measured with LA-ICPMS. The distribution of REE between hornblende and clinopyroxene in the tholeiitic rocks is similar for most of the elements (DHbl•Cpx(La-Tm) = 2.7-2.8, decreasing to 2.6 and 2.4 for Yb and Lu, respectively). These values are about two times higher than published data (e.g. Ionov et al. 1997). Partition coefficients for orthopyroxene/clinopyroxene systematically decrease from the HREE

Compositional and phase relations among rare earth element minerals

NASA Technical Reports Server (NTRS)

Burt, D. M.

1990-01-01

This paper discusses the compositional and phase relationships among minerals in which rare earth elements (REE) occur as essential constituents (e.g., bastnaesite, monazite, xenotime, aeschynite, allanite). Particular consideration is given to the vector representation of complex coupled substitutions in selected REE-bearing minerals and to the REE partitioning between minerals as related to the acid-base tendencies and mineral stabilities. It is shown that the treatment of coupled substitutions as vector quantities facilitates graphical representation of mineral composition spaces.

Behavior and Distribution of Heavy Metals Including Rare Earth Elements, Thorium, and Uranium in Sludge from Industry Water Treatment Plant and Recovery Method of Metals by Biosurfactants Application

PubMed Central

Gao, Lidi; Kano, Naoki; Sato, Yuichi; Li, Chong; Zhang, Shuang; Imaizumi, Hiroshi

2012-01-01

In order to investigate the behavior, distribution, and characteristics of heavy metals including rare earth elements (REEs), thorium (Th), and uranium (U) in sludge, the total and fractional concentrations of these elements in sludge collected from an industry water treatment plant were determined and compared with those in natural soil. In addition, the removal/recovery process of heavy metals (Pb, Cr, and Ni) from the polluted sludge was studied with biosurfactant (saponin and sophorolipid) elution by batch and column experiments to evaluate the efficiency of biosurfactant for the removal of heavy metals. Consequently, the following matters have been largely clarified. (1) Heavy metallic elements in sludge have generally larger concentrations and exist as more unstable fraction than those in natural soil. (2) Nonionic saponin including carboxyl group is more efficient than sophorolipid for the removal of heavy metals in polluted sludge. Saponin has selectivity for the mobilization of heavy metals and mainly reacts with heavy metals in F3 (the fraction bound to carbonates) and F5 (the fraction bound to Fe-Mn oxides). (3) The recovery efficiency of heavy metals (Pb, Ni, and Cr) reached about 90–100% using a precipitation method with alkaline solution. PMID:22693485

Ternary alkali-metal and transition metal or metalloid acetylides as alkali-metal intercalation electrodes for batteries

DOEpatents

Nemeth, Karoly; Srajer, George; Harkay, Katherine C; Terdik, Joseph Z

2015-02-10

Novel intercalation electrode materials including ternary acetylides of chemical formula: A.sub.nMC.sub.2 where A is alkali or alkaline-earth element; M is transition metal or metalloid element; C.sub.2 is reference to the acetylide ion; n is an integer that is 0, 1, 2, 3 or 4 when A is alkali element and 0, 1, or 2 when A is alkaline-earth element. The alkali elements are Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs) and Francium (Fr). The alkaline-earth elements are Berilium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra). M is a transition metal that is any element in groups 3 through 12 inclusive on the Periodic Table of Elements (elements 21 (Sc) to element 30 (Zn)). In another exemplary embodiment, M is a metalloid element.

Oxygen regime of Siberian alkaline-ultramafic magmas

NASA Astrophysics Data System (ADS)

Ryabchikov, Igor; Kogarko, Liya

2017-04-01

Regimes of S2 and O2 are decisive factors controlling behavior of chalcophile and siderophile elements in magmatic processes. These parameters play important role during magmagenesis and in the course of crystallization and fluid mass transfer in magma chamber. Alkaline-ultramafic magmatism in Maymecha-Kotuy Province (Polar Siberia) is represented by giant intrusive complexes as well as by volcanics and dyke rocks, which include a well-known variety - meimechites. The latter are considered primary magmas of alkaline-ultramafic plutons in the region like for instance Guli intrusive complex. Sulfur content in primitive magmas estimated from the analyses of melt inclusions in olivine megacrysts from meimechites is close to 0.1 %. fO2 values calculated using olivine+clinopyroxene+spinel and spinel+melt oxygen barometers (1, 2) are 2-3 log units above QFM buffer. The relatively high oxygen potential at the early magmatic stage of alkaline-ultramafic Guli pluton provide predominance of sulfates among other forms of sulfur in the melt. This leads to the almost complete absence of sulfides in highly magnesian rocks. The oxidizing conditions exert important effect on behavior of many ore metals. At the stage of magma generation absence of sulfides in mantle materialresults in the presence of siderophile elements in metallic form and saturation of primary magmas in respect of metallic phases at an early stage of injection of the melt into the magma chamber. Later, under favorable circumstances during magma crystallization nuggets of precious metals may be formed. During further evolution of magmatic system fO2 and activity of oxidized sulfur decrease due to intensive crystallization of magnetite during the formation of koswites, then oxygen fugacity becomes even lower as a result serpentinization at a postmagmatic stage. These serpentization processes are caused by the displacement of reactions in the aqueous phase due to cooling towards the formation of methane and other

Advanced technology for extended endurance alkaline fuel cells

NASA Technical Reports Server (NTRS)

Sheibley, D. W.; Martin, R. A.

1987-01-01

Advanced components have been developed for alkaline fuel cells with a view to the satisfaction of NASA Space Station design requirements for extended endurance. The components include a platinum-on-carbon catalyst anode, a potassium titanate-bonded electrolyte matrix, a lightweight graphite electrolyte reservoir plate, a gold-plated nickel-perforated foil electrode substrate, a polyphenylene sulfide cell edge frame material, and a nonmagnesium cooler concept. When incorporated into the alkaline fuel cell unit, these components are expected to yield regenerative operation in a low earth orbit Space Station with a design life greater than 5 years.

Exploring the limits of EDS microanalysis: rare earth element analyses

NASA Astrophysics Data System (ADS)

Ritchie, N. W. M.; Newbury, D. E.; Lowers, H.; Mengason, M.

2018-01-01

It is a great time to be a microanalyst. After a few decades of incremental progress in energy-dispersive X-ray spectrometry (EDS), the last decade has seen the accuracy and precision surge forward. Today, the question is not whether EDS is generally useful but to identify the types of problems for which wavelength-dispersive X-ray spectrometry remains the better choice. The full extent of EDS’s capabilities has surprised many. Low Z, low energy, and trace element detection have been demonstrated even in the presence of extreme peak interferences. In this paper, we will summarise the state-of-the-art and investigate a challenging problem domain, the analysis of minerals bearing multiple rare-earth elements.

Methanol synthesis using a catalyst combination of alkali or alkaline earth salts and reduced copper chromite

DOEpatents

Tierney, J.W.; Wender, I.; Palekar, V.M.

1995-01-24

The present invention relates to a novel route for the synthesis of methanol, and more specifically to the production of methanol by contacting synthesis gas under relatively mild conditions in a slurry phase with a catalyst combination comprising reduced copper chromite and basic alkali salts or alkaline earth salts. The present invention allows the synthesis of methanol to occur in the temperature range of approximately 100--160 C and the pressure range of 40--65 atm. The process produces methanol with up to 90% syngas conversion per pass and up to 95% methanol selectivity. The only major by-product is a small amount of easily separated methyl formate. Very small amounts of water, carbon dioxide and dimethyl ether are also produced. The present catalyst combination also is capable of tolerating fluctuations in the H[sub 2]/CO ratio without major deleterious effect on the reaction rate. Furthermore, carbon dioxide and water are also tolerated without substantial catalyst deactivation.

Process for depositing epitaxial alkaline earth oxide onto a substrate and structures prepared with the process

DOEpatents

McKee, Rodney A.; Walker, Frederick J.

1996-01-01

A process and structure involving a silicon substrate utilize molecular beam epitaxy (MBE) and/or electron beam evaporation methods and an ultra-high vacuum facility to grow a layup of epitaxial alkaline earth oxide films upon the substrate surface. By selecting metal constituents for the oxides and in the appropriate proportions so that the lattice parameter of each oxide grown closely approximates that of the substrate or base layer upon which oxide is grown, lattice strain at the film/film or film/substrate interface of adjacent films is appreciably reduced or relieved. Moreover, by selecting constituents for the oxides so that the lattice parameters of the materials of adjacent oxide films either increase or decrease in size from one parameter to another parameter, a graded layup of films can be grown (with reduced strain levels therebetween) so that the outer film has a lattice parameter which closely approximates that of, and thus accomodates the epitaxial growth of, a pervoskite chosen to be grown upon the outer film.

Methanol synthesis using a catalyst combination of alkali or alkaline earth salts and reduced copper chromite

DOEpatents

Tierney, John W.; Wender, Irving; Palekar, Vishwesh M.

1995-01-01

The present invention relates to a novel route for the synthesis of methanol, and more specifically to the production of methanol by contacting synthesis gas under relatively mild conditions in a slurry phase with a catalyst combination comprising reduced copper chromite and basic alkali salts or alkaline earth salts. The present invention allows the synthesis of methanol to occur in the temperature range of approximately 100.degree.-160.degree. C. and the pressure range of 40-65 atm. The process produces methanol with up to 90% syngas conversion per pass and up to 95% methanol selectivity. The only major by-product is a small amount of easily separated methyl formate. Very small amounts of water, carbon dioxide and dimethyl ether are also produced. The present catalyst combination also is capable of tolerating fluctuations in the H.sub.2 /CO ratio without major deleterious effect on the reaction rate. Furthermore, carbon dioxide and water are also tolerated without substantial catalyst deactivation.

Physical and optical absorption studies of Fe{sup 3+} - ions doped lithium borate glasses containing certain alkaline earths

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

Bhogi, Ashok; Kumar, R. Vijaya; Kistaiah, P., E-mail: pkistaiah@yahoo.com

Iron ion doped lithium borate glasses with the composition 15RO-25Li{sub 2}O-59B{sub 2}O{sub 3}-1Fe{sub 2}O{sub 3} (where R= Ca, Sr and Ba) have been prepared by the conventional melt quenching technique and characterized to investigate the physical and optical properties using XRD, density, molar volume and UV-Visible spectroscopy. The optical absorption spectra exhibit a band at around 460 nm which is assigned to {sup 6}A{sub 1g}(S) → 4E{sub g} (G) of Fe{sup 3+} ions with distorted octahedral symmetry. From ultraviolet absorption edges, the optical band gap and Urbach energies have been evaluated. The effect of alkaline earths on these properties ismore » discussed.« less

Mixed alkali effect on the spectroscopic properties of alkali-alkaline earth oxide borate glasses

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

Srinivas, G., E-mail: srinu123g@gmail.com; Ramesh, B.; Shareefuddin, Md.

2016-05-06

The mixed alkali and alkaline earth oxide borate glass with the composition xK{sub 2}O - (25-x) Li{sub 2}O-12.5BaO-12.5MgO-50B{sub 2}O{sub 3} (x = 0, 5, 10, 15, 20 and 25mol %) and doped with 1mol% CuO were prepared by the melt quenching technique. From the optical absorption spectra the optical band gap, electronic polarizability(α{sub 0}2-), interaction parameter (A), theoretical and experimental optical basicity (Λ) values were evaluated. From the Electron Paramagnetic Resonance (EPR) spectral data the number of spins (N) and susceptibility (χ) were evaluated. The values of (α{sub 0}2-), and (Λ) increases with increasing of K{sub 2}O content and electronicmore » polarizability and interaction parameter show opposite behaviuor which may be due to the creation of non-bridging oxygens and expansion of borate network. The reciprocal of susceptibility (1/χ) and spin concentration (N) as a function of K{sub 2}O content, varied nonlinearly which may be due to creation of non-bridging oxygens in the present glass system. This may be attributed to mixed alkali effect (MAE).« less

Chemical speciation and bioavailability of rare earth elements (REEs) in the ecosystem: a review.

PubMed

Khan, Aysha Masood; Bakar, Nor Kartini Abu; Bakar, Ahmad Farid Abu; Ashraf, Muhammad Aqeel

2017-10-01

Rare earths (RE), chemically uniform group of elements due to similar physicochemical behavior, are termed as lanthanides. Natural occurrence depends on the geological circumstances and has been of long interest for geologist as tools for further scientific research into the region of ores, rocks, and oceanic water. The review paper mainly focuses to provide scientific literature about rare earth elements (REEs) with potential environmental and health effects in understanding the research. This is the initial review of RE speciation and bioavailability with current initiative toward development needs and research perceptive. In this paper, we have also discussed mineralogy, extraction, geochemistry, analytical methods of rare earth elements. In this study, REEs with their transformation and vertical distribution in different environments such as fresh and seawater, sediments, soil, weathering, transport, and solubility have been reported with most recent literature along key methods of findings. Speciation and bioavailability have been discussed in detail with special emphasis on soil, plant, and aquatic ecosystems and their impacts on the environment. This review shows that REE gained more importance in last few years due to their detrimental effects on living organisms, so their speciation, bioavailability, and composition are much more important to evaluate their health risks and are discussed thoroughly as well.

Standard reference water samples for rare earth element determinations

USGS Publications Warehouse

Verplanck, P.L.; Antweiler, Ronald C.; Nordstrom, D. Kirk; Taylor, Howard E.

2001-01-01

Standard reference water samples (SRWS) were collected from two mine sites, one near Ophir, CO, USA and the other near Redding, CA, USA. The samples were filtered, preserved, and analyzed for rare earth element (REE) concentrations (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) by inductively coupled plasma-mass spectrometry (ICP-MS). These two samples were acid mine waters with elevated concentrations of REEs (0.45-161 ??g/1). Seventeen international laboratories participated in a 'round-robin' chemical analysis program, which made it possible to evaluate the data by robust statistical procedures that are insensitive to outliers. The resulting most probable values are reported. Ten to 15 of the participants also reported values for Ba, Y, and Sc. Field parameters, major ion, and other trace element concentrations, not subject to statistical evaluation, are provided.

Tracing sediment movement on semi-arid watershed using Rare Earth Elements 1988

USDA-ARS?s Scientific Manuscript database

A multi-tracer method employing rare earth elements (REE) was used to determine sediment yield and to track sediment movement in a small semiarid watershed. A 0.33 ha watershed near Tombstone, AZ was divided into five morphological units, each tagged with one of five REE oxides. Relative contributi...

A volatile topic: Parsing out the details of Earth's formation through experimental metal-silicate partitioning of volatile and moderately volatile elements

NASA Astrophysics Data System (ADS)

Mahan, B. M.; Siebert, J.; Blanchard, I.; Badro, J.; Sossi, P.; Moynier, F.

2017-12-01

Volatile and moderately volatile elements display different volatilities and siderophilities, as well as varying sensitivity to thermodynamic controls (X, P, T, fO2) during metal-silicate differentiation. The experimental determination of the metal-silicate partitioning of these elements permits us to evaluate processes controlling the distribution of these elements in Earth. In this work, we have combined metal-silicate partitioning data and results for S, Sn, Zn and Cu, and input these characterizations into Earth formation models. Model parameters such as source material, timing of volatile delivery, fO2 path, and degree of impactor equilibration were varied to encompass an array of possible formation scenarios. These models were then assessed to discern plausible sets of conditions that can produce current observed element-to-element ratios (e.g. S/Zn) in the Earth's present-day mantle, while also satisfying current estimates on the S content of the core, at no more than 2 wt%. The results of our models indicate two modes of accretion that can maintain chondritic element-to-element ratios for the bulk Earth and can arrive at present-day mantle abundances of these elements. The first mode requires the late addition of Earth's entire inventory of these elements (assuming a CI-chondritic composition) and late-stage accretion that is marked by partial equilibration of large impactors. The second, possibly more intuitive mode, requires that Earth accreted - at least initially - from volatile poor material preferentially depleted in S relative to Sn, Zn, and Cu. From a chemical standpoint, this source material is most similar to type I chondrule rich (and S poor) materials (Hewins and Herzberg, 1996; Mahan et al., 2017; Amsellem et al., 2017), such as the metal-bearing carbonaceous chondrites.

Hydrometallurgical separation of rare earth elements, cobalt and nickel from spent nickel-metal-hydride batteries

NASA Astrophysics Data System (ADS)

Rodrigues, Luiz Eduardo Oliveira Carmo; Mansur, Marcelo Borges

The separation of rare earth elements, cobalt and nickel from NiMH battery residues is evaluated in this paper. Analysis of the internal content of the NiMH batteries shows that nickel is the main metal present in the residue (around 50% in weight), as well as potassium (2.2-10.9%), cobalt (5.1-5.5%), rare earth elements (15.3-29.0%) and cadmium (2.8%). The presence of cadmium reveals that some Ni-Cd batteries are possibly labeled as NiMH ones. The leaching of nickel and cobalt from the NiMH battery powder with sulfuric acid is efficient; operating variables temperature and concentration of H 2O 2 has no significant effect for the conditions studied. A mixture of rare earth elements is separated by precipitation with NaOH. Finally, solvent extraction with D2EHPA (di-2-ethylhexyl phosphoric acid) followed by Cyanex 272 (bis-2,4,4-trimethylpentyl phosphinic acid) can separate cadmium, cobalt and nickel from the leach liquor. The effect of the main operating variables of both leaching and solvent extraction steps are discussed aiming to maximize metal separation for recycling purposes.

Highly alkaline lavas in a Proterozoic rift zone: Implications for Precambrian mantle metasomatic processes

NASA Astrophysics Data System (ADS)

Gaonac'h, H.; Ludden, J. N.; Picard, C.; Francis, D.

1992-03-01

An occurrence of Proterozoic nephelinite and basanite lavas and pyroclastic rocks and associated phonolites indicates that the processes that generate modern alkaline magmas in intraplate settings were operative in the Early Proterozoic. These lavas occur near the top of a 1.9 Ga continental-margin sequence in the Cape Smith fold and thrust belt of northern Quebec. The lavas are classified as nephelinites, basanites, and phonolites on the basis of high field strength and rare earth element contents, although large ion lithophile elements, including alkalis, appear to have been strongly depleted by greenschist facies metamorphism and alteration. Certain major elements define trends consistent with low-pressure fractionation dominated by clinopyroxene, which is the only mafic phenocryst present in the lavas. The mafic and felsic lavas have identical 143Nd/144Nd ratios, consistent with consanguinity and a lack of contamination by older crust of the Superior province. Values for ɛNd (1.96 Ga) of +2 represent an enriched mantle source relative to +4 to +5 for the contemporaneous mid-oceanic-ridge basalt reservoir.

Rare-earth elements enrichment of Pacific seafloor sediments: the view from volcanic islands of Polynesia

NASA Astrophysics Data System (ADS)

Melleton, Jérémie; Tuduri, Johann; Pourret, Olivier; Bailly, Laurent; Gisbert, Thierry

2014-05-01

Rare-earth elements (REEs) are key metals for «green» technologies such as energy saving lamps or permanent magnets used in, e.g., wind turbines, hard disk drives, portable phone or electric or hybrid vehicles. Since several years, world demand for these metals is therefore drastically increasing. The quasi-monopolistic position of China, which produces around 95 % of global REEs production, generates risks for the industries that depend on a secure supply of REEs. In response, countries are developing and diversifying their supply sources, with new mining projects located outside China and efforts in the area of REEs recycling. Most of these projects focus on deposits related to carbonatites and alkaline-peralkaline magmatism, which are generally enriched in light REEs (LREEs) compared to the heavy REEs (HREEs)-enriched deposits of the ion-adsorption types, located in southern China. However, a recent study revealed new valuable resources corresponding to seafloor sediments located in the south-eastern and north-central Pacific. The deep-sea mud described by these authors show a higher HREE/LREE ratio than ion-adsorption deposits, a feature which significantly increases their economic interest. The authors suggest mid-ocean ridge hydrothermal activity as an explanation to this anomalous enrichment. However, several contributions have documented considerable REEs enrichment in basalts and peridotitic xenoliths from French Polynesia. Several arguments have been exposed in favour of a supergene origin, with a short migration, suggesting that REEs were collected from weathered basalts. The Tahaa volcanic island (Sous-le-Vent Island, Society Archipelago, French Polynesia) is the first location where such enrichment has been described. New petrographic and mineralogical investigations confirm a supergene mobilization of this abnormal occurrence. REE-bearing minerals (mainly phosphates of the rhabdophane group) are primarily located within basalt vesicles but also in

Emission properties of Ce-doped alkaline earth borate glasses for scintillator applications

NASA Astrophysics Data System (ADS)

Torimoto, Aya; Masai, Hirokazu; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

2017-11-01

We investigate the photoluminescence (PL) and X-ray-induced luminescence properties of 0.1 mol% Ce-doped MO-B2O3 (M = Ca, Sr, and Ba) glasses. We also determine the Ce3+/(Ce3++Ce4+) ratio by X-ray absorption near-edge structure analyses. The emission intensities of PL, X-ray scintillation, and thermally stimulated luminescence (TSL) depend on the host glass composition. The order of the PL intensity from highest to lowest is as follows: Ca-substituted glass, Ba-substituted glass, and Sr-substituted glass. Our results suggest that the optical absorption edge and quantum yield (QY) are influenced by the local coordination state of Ce3+, which, in turn, is likely to be affected by the optical basicity. The order of the X-ray scintillation intensity from highest to lowest is reverse of that of the PL intensity. This is probably because the interaction probability of X-rays with matter depends on the effective atomic number of the material and the effective atomic number has a stronger influence on the scintillation intensity than does the QY. Though the TSL glow curves reveal that the density and energy depth of the trap sites depend on the substituted alkaline earth oxides, we are unable to correlate the electron spin resonance (ESR) spectra with the TSL results. Therefore, it is considered that the ESR active sites are not responsible for the TSL in these systems.

Tipping elements in the Earth's climate system

PubMed Central

Lenton, Timothy M.; Held, Hermann; Kriegler, Elmar; Hall, Jim W.; Lucht, Wolfgang; Rahmstorf, Stefan; Schellnhuber, Hans Joachim

2008-01-01

The term “tipping point” commonly refers to a critical threshold at which a tiny perturbation can qualitatively alter the state or development of a system. Here we introduce the term “tipping element” to describe large-scale components of the Earth system that may pass a tipping point. We critically evaluate potential policy-relevant tipping elements in the climate system under anthropogenic forcing, drawing on the pertinent literature and a recent international workshop to compile a short list, and we assess where their tipping points lie. An expert elicitation is used to help rank their sensitivity to global warming and the uncertainty about the underlying physical mechanisms. Then we explain how, in principle, early warning systems could be established to detect the proximity of some tipping points. PMID:18258748

Sustainability of rare earth elements chain: from production to food - a review.

PubMed

Turra, Christian

2018-02-01

Rare earth elements (REE) are a group of chemical elements that include lanthanoids (lanthanum to lutetium), scandium and yttrium. In the last decades, the REE demand in the industry and other areas has increased significantly. In general, REE have shown low concentrations in soils, plants, water and atmosphere, but they may accumulate in such environments due to anthropogenic inputs. In areas where there is REE contamination, the slow accumulation of these elements in the environment could become problematic. Many studies have shown environmental areas contaminated with REE and their toxic effects. Thus, it is important to review, in order to improve the current understanding of these elements in the environment, showing the effects of REE exposure in mining, soil, water, plants and food. Besides, there are few suppliers and a limited quantity of these elements in the world. This paper suggests options to improve the sustainability management of REE chain.

The Earth Based Ground Stations Element of the Lunar Program

NASA Technical Reports Server (NTRS)

Gal-Edd, Jonathan; Fatig, Curtis; Schier, James; Lee, Charles

2007-01-01

The Lunar Architecture Team (LAT) is responsible for developing a concept for building and supporting a lunar outpost with several exploration capabilities such as rovers, colonization, and observatories. The lunar outpost is planned to be located at the Moon's South Pole. The LAT Communications and Navigation Team (C&N) is responsible for defining the network infrastructure to support the lunar outpost. The following elements are needed to support lunar outpost activities: A Lunar surface network based on industry standard wireless 802.xx protocols, relay satellites positioned 180 degrees apart to provide South Pole coverage for the half of the lunar 28-day orbit that is obscured from Earth view, earth-based ground stations deployed at geographical locations 120 degrees apart. This paper will focus on the Earth ground stations of the lunar architecture. Two types of ground station networks are discussed. One provides Direct to Earth (DTE) support to lunar users using Kaband 23/26Giga-Hertz (GHz) communication frequencies. The second supports the Lunar Relay Satellite (LRS) that will be using Ka-band 40/37GHz (Q-band). This paper will discuss strategies to provide a robust operational network in support of various lunar missions and trades of building new antennas at non-NASA facilities, to improve coverage and provide site diversification for handling rain attenuation.

Rare earth elements recycling from waste phosphor by dual hydrochloric acid dissolution.

PubMed

Liu, Hu; Zhang, Shengen; Pan, Dean; Tian, Jianjun; Yang, Min; Wu, Maolin; Volinsky, Alex A

2014-05-15

This paper is a comparative study of recycling rare earth elements from waste phosphor, which focuses on the leaching rate and the technical principle. The traditional and dual dissolution by hydrochloric acid (DHA) methods were compared. The method of dual dissolution by hydrochloric acid has been developed. The Red rare earth phosphor (Y0.95Eu0.05)2O3 in waste phosphor is dissolved during the first step of acid leaching, while the Green phosphor (Ce0.67Tb0.33MgAl11O19) and the Blue phosphor (Ba0.9Eu0.1MgAl10O17) mixed with caustic soda are obtained by alkali sintering. The excess caustic soda and NaAlO2 are removed by washing. The insoluble matter is leached by the hydrochloric acid, followed by solvent extraction and precipitation (the DHA method). In comparison, the total leaching rate of the rare earth elements was 94.6% by DHA, which is much higher than 42.08% achieved by the traditional method. The leaching rate of Y, Eu, Ce and Tb reached 94.6%, 99.05%, 71.45%, and 76.22%, respectively. DHA can decrease the consumption of chemicals and energy. The suggested DHA method is feasible for industrial applications. Copyright © 2014 Elsevier B.V. All rights reserved.

When can ocean acidification impacts be detected from decadal alkalinity measurements?

NASA Astrophysics Data System (ADS)

Carter, B. R.; Frölicher, T. L.; Dunne, J. P.; Rodgers, K. B.; Slater, R. D.; Sarmiento, J. L.

2016-04-01

We use a large initial condition suite of simulations (30 runs) with an Earth system model to assess the detectability of biogeochemical impacts of ocean acidification (OA) on the marine alkalinity distribution from decadally repeated hydrographic measurements such as those produced by the Global Ship-Based Hydrographic Investigations Program (GO-SHIP). Detection of these impacts is complicated by alkalinity changes from variability and long-term trends in freshwater and organic matter cycling and ocean circulation. In our ensemble simulation, variability in freshwater cycling generates large changes in alkalinity that obscure the changes of interest and prevent the attribution of observed alkalinity redistribution to OA. These complications from freshwater cycling can be mostly avoided through salinity normalization of alkalinity. With the salinity-normalized alkalinity, modeled OA impacts are broadly detectable in the surface of the subtropical gyres by 2030. Discrepancies between this finding and the finding of an earlier analysis suggest that these estimates are strongly sensitive to the patterns of calcium carbonate export simulated by the model. OA impacts are detectable later in the subpolar and equatorial regions due to slower responses of alkalinity to OA in these regions and greater seasonal equatorial alkalinity variability. OA impacts are detectable later at depth despite lower variability due to smaller rates of change and consistent measurement uncertainty.

Alkaline-earth metal carboxylates characterized by 43Ca and 87Sr solid-state NMR: impact of metal-amine bonding.

PubMed

Burgess, Kevin M N; Xu, Yang; Leclerc, Matthew C; Bryce, David L

2014-01-06

A series of calcium and strontium complexes featuring aryl carboxylate ligands has been prepared and characterized by alkaline-earth ((43)Ca and (87)Sr) solid-state NMR experiments in a magnetic field of 21.1 T. In the 11 compounds studied as part of this work, a range of coordination motifs are observed including nitrogen atom binding to Ca(2+) and Sr(2+), a binding mode which has not been investigated previously by (43)Ca or (87)Sr solid-state NMR. (43)Ca isotopic enrichment has enabled the full characterization of the (43)Ca electric field gradient (EFG) and chemical shift tensors of the two calcium sites in calcium p-aminosalicylate (Ca(pams)), where both NMR interactions are affected by the presence of a nitrogen atom in the first coordination sphere of one of the metal sites. The (43)Ca isotropic chemical shift is sensitive to the Ca-N distance as exemplified by the NMR parameters of a second form of Ca(pams) and density functional theory (DFT) calculations. Studies of the strontium analogue, Sr(pams), confirm a similar sensitivity of the (87)Sr EFG tensor to the presence or absence of nitrogen in the first coordination sphere. To our knowledge, this is the first systematic (87)Sr NMR study of strontium complexes featuring organic ligands. The |CQ((87)Sr)| values are found to be sensitive to the coordination number about Sr(2+). In general, this work has also established a larger data set of reliable experimental |CQ((43)Ca)| values which correlate well with those obtained using gauge-including projector-augmented-wave (GIPAW) DFT calculations. It is found that the use of a recently recommended quadrupole moment for (43)Ca, -44.4 mbarn, improves the agreement with experimental values. This contribution lays the groundwork for the interpretation of (43)Ca and (87)Sr NMR spectra of more challenging systems, particularly where nitrogen-alkaline earth metal bonding is occurring.

Enhanced separation of rare earth elements

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

Lyon, K.; Greenhalgh, M.; Herbst, R. S.

2016-09-01

Industrial rare earth separation processes utilize PC88A, a phosphonic acid ligand, for solvent extraction separations. The separation factors of the individual rare earths, the equipment requirements, and chemical usage for these flowsheets are well characterized. Alternative ligands such as Cyanex® 572 and the associated flowsheets are being investigated at the pilot scale level to determine if significant improvements to the current separation processes can be realized. These improvements are identified as higher separation factors, reduced stage requirements, or reduced chemical consumption. Any of these improvements can significantly affect the costs associated with these challenging separation proccesses. A mid/heavy rare earthmore » element (REE) separations flowsheet was developed and tested for each ligand in a 30 stage mixer-settler circuit to compare the separation performance of PC88A and Cyanex® 572. The ligand-metal complex strength of Cyanex® 572 provides efficient extraction of REE while significantly reducing the strip acid requirements. Reductions in chemical consumption have a significant impact on process economics for REE separations. Partitioning results summarized Table 1 indicate that Cyanex® 572 offers the same separation performance as PC88A while reducing acid consumption by 30% in the strip section for the mid/heavy REE separation. Flowsheet Effluent Compositions PC88A Cyanex® 572 Raffinate Mid REE Heavy REE 99.40% 0.60% 99.40% 0.60% Rich Mid REE Heavy REE 2.20% 97.80% 0.80% 99.20% Liquor Strip Acid Required 3.4 M 2.3 M Table 1 – Flowsheet results comparing separation performance of PC88A and Cyanex® 572 for a mid/heavy REE separation.« less

Sources of Extraterrestrial Rare Earth Elements:To the Moon and Beyond

NASA Astrophysics Data System (ADS)

McLeod, C. L.; Krekeler, M. P. S.

2017-08-01

The resource budget of Earth is limited. Rare-earth elements (REEs) are used across the world by society on a daily basis yet several of these elements have <2500 years of reserves left, based on current demand, mining operations, and technologies. With an increasing population, exploration of potential extraterrestrial REE resources is inevitable, with the Earth's Moon being a logical first target. Following lunar differentiation at 4.50-4.45 Ga, a late-stage (after 99% solidification) residual liquid enriched in Potassium (K), Rare-earth elements (REE), and Phosphorus (P), (or "KREEP") formed. Today, the KREEP-rich region underlies the Oceanus Procellarum and Imbrium Basin region on the lunar near-side (the Procellarum KREEP Terrain, PKT) and has been tentatively estimated at preserving 2.2 × 10^8 km^3 of KREEP-rich lithologies. The majority of lunar samples (Apollo, Luna, or meteoritic samples) contain REE-bearing minerals as trace phases, e.g., apatite and/or merrillite, with merrillite potentially contributing up to 3% of the PKT. Other lunar REE-bearing lunar phases include monazite, yittrobetafite (up to 94,500 ppm yttrium), and tranquillityite (up to 4.6 wt % yttrium, up to 0.25 wt % neodymium), however, lunar sample REE abundances are low compared to terrestrial ores. At present, there is no geological, mineralogical, or chemical evidence to support REEs being present on the Moon in concentrations that would permit their classification as ores. However, the PKT region has not yet been mapped at high resolution, and certainly has the potential to yield higher REE concentrations at local scales (<10s of kms). Future lunar exploration and mapping efforts may therefore reveal new REE deposits. Beyond the Moon, Mars and other extraterrestrial materials are host to REEs in apatite, chevkinite-perrierite, merrillite, whitlockite, and xenotime. These phases are relatively minor components of the meteorites studied to date, constituting <0.6% of the total sample

Rare earth elements geochemistry in springs from Taftan geothermal area SE Iran

NASA Astrophysics Data System (ADS)

Shakeri, Ata; Ghoreyshinia, Sayedkazem; Mehrabi, Behzad; Delavari, Morteza

2015-10-01

Concentrations of rare earth elements (REEs) were determined in springs and andesitic-dacitic rocks of Taftan geothermal field. Hydrochemical results of major ions indicate that thermal springs are Na-SO4-Cl and Ca-SO4-Cl types. Concentrations of REEs are in ranges of 10- 4 to 1.2 and 49 to 62 times of chondrite for springwater and rock samples, respectively. The thermal (STS and TTS) and the cold (APS) springs with low pH values exhibit a very high REE contents (0.64 to 3.15 mg/l). Saturation index indicates that Fe and Al phases can control dissolved REE concentration in FTS and PF cold springs. The speciation of REE complexes indicates dominant presence of LnSO4+ and free ion in the Taftan thermal springs. In APS cold spring with pH 4, fluoride complexes are dominate over the free ion and sulfate species, while in PF and FTS cold springs with pH 6.4 and 7, respectively, carbonate complexes (LnCO3+) are predominant species. Chondrite-normalized pattern for the low-pH waters show very distinctive gull-wing patterns, characteristic feature of acid-sulfate geothermal systems, and are similar to those of the host rocks. Chemical characteristics of rare earth elements in spring and volcanic rock samples indicate that REEs are originated from the andesitic-dacitic host rocks. Whole-rock-normalized REE patterns and petrographic evidences show that rare earth elements leached mainly from marginal alteration of minerals and matrix decomposition in volcanic rocks. In chondrite-normalized REE patterns, significant negative Eu anomaly in the cold springs compare to the thermal and acidic springs indicates that alteration of plagioclase is more intense in the later, corresponding to increasing in temperature and acidic state of reactant water.

(BRI) Direct and Inverse Design Optimization of Magnetic Alloys with Minimized Use of Rare Earth Elements

DTIC Science & Technology

2016-02-02

Earths ”, MS&T15-Materials Science and Technology 2015 Conference, Columbus, Ohio, October 4-8, 2015. 3. Dulikrvich, G.S., Reddy, S., Orlande, H.R.B...Schwartz, J.and Koch, C.C., “Multi-Objective Design and Optimization of Hard Magnetic Alloys Free of Rare Earths ”, MS&T15-Materials Science and Technology...AFRL-AFOSR-VA-TR-2016-0091 (BRI) Direct and Inverse Design Optimization of Magnetic Alloys with Minimized Use of Rare Earth Elements George

[Rare earth elements content in farmland soils and crops of the surrounding copper mining and smelting plant in Jiangxi province and evaluation of its ecological risk].

PubMed

Jin, Shu-Lan; Huang, Yi-Zong; Wang, Fei; Xu, Feng; Wang, Xiao-Ling; Gao, Zhu; Hu, Ying; Qiao Min; Li, Jin; Xiang, Meng

2015-03-01

Rare earth elements content in farmland soils and crops of the surrounding copper mining and smelting plant in Jiangxi province was studied. The results showed that copper mining and smelting could increase the content of rare earth elements in soils and crops. Rare earth elements content in farmland soils of the surrounding Yinshan Lead Zinc Copper Mine and Guixi Smelting Plant varied from 112.42 to 397.02 mg x kg(-1) and 48.81 to 250.06 mg x kg(-1), and the average content was 254.84 mg x kg(-1) and 144.21 mg x kg(-1), respectively. The average contents of rare earth elements in soils in these two areas were 1.21 times and 0.68 times of the background value in Jiangxi province, 1.36 times and 0.77 times of the domestic background value, 3.59 times and 2.03 times of the control samples, respectively. Rare earth elements content in 10 crops of the surrounding Guixi Smelting Plant varied from 0.35 to 2.87 mg x kg(-1). The contents of rare earth elements in the leaves of crops were higher than those in stem and root. The contents of rare earth elements in Tomato, lettuce leaves and radish leaves were respectively 2.87 mg x kg(-1), 1.58 mg x kg(-1) and 0.80 mg x kg(-1), which were well above the hygienic standard limit of rare earth elements in vegetables and fruits (0.70 mg x kg(-1)). According to the health risk assessment method recommended by America Environmental Protection Bureau (USEPA), we found that the residents' lifelong average daily intake of rare earth elements was 17.72 mg x (kg x d)(-1), lower than the critical value of rare earth elements damage to human health. The results suggested that people must pay attention to the impact of rare earth elements on the surrounding environment when they mine and smelt copper ore in Jiangxi.

Interactions between exogenous rare earth elements and phosphorus leaching in packed soil columns

USDA-ARS?s Scientific Manuscript database

Rare earth elements (REEs) increasingly used in agriculture as an amendment for crop growth may help to lessen environmental losses of phosphorus (P) from heavily fertilized soils. The vertical transport characteristics of P and REEs, lanthanum (La), neodymium (Nd), samarium (Sm), and cerium (Ce), w...

Compositional and phase relations among rare earth element minerals

NASA Technical Reports Server (NTRS)

Burt, D. M.

1989-01-01

A review is presented that mainly treats minerals in which the rare-earth elements are essential constituents, e.g., bastnaesite, monazite, xenotime, aeschynite, allanite. The chemical mechanisms and limits of REE substitution in some rock-forming minerals (zircon, apatite, titanite, garnet) are also derived. Vector representation of complex coupled substitutions in selected REE-bearing minerals is examined and some comments on REE-partitioning between minerals as related to acid-based tendencies and mineral stabilities are presented. As the same or analogous coupled substitutions involving the REE occur in a wide variety of mineral structures, they are discussed together.

Alkali and alkaline earth metallic (AAEM) species leaching and Cu(II) sorption by biochar.

PubMed

Li, Mi; Lou, Zhenjun; Wang, Yang; Liu, Qiang; Zhang, Yaping; Zhou, Jizhi; Qian, Guangren

2015-01-01

Alkali and alkaline earth metallic (AAEM) species water leaching and Cu(II) sorption by biochar prepared from two invasive plants, Spartina alterniflora (SA) and water hyacinth (WH), were explored in this work. Significant amounts of Na and K can be released (maximum leaching for Na 59.0 mg g(-1) and K 79.9 mg g(-1)) from SA and WH biochar when they are exposed to contact with water. Cu(II) removal by biochar is highly related with pyrolysis temperature and environmental pH with 600-700 °C and pH of 6 showing best performance (29.4 and 28.2 mg g(-1) for SA and WH biochar). Cu(II) sorption exerts negligible influence on Na/K/Mg leaching but clearly promotes the release of Ca. Biochars from these two plant species provide multiple benefits, including nutrient release (K), heavy metal immobilization as well as promoting the aggregation of soil particles (Ca) for soil amelioration. AAEM and Cu(II) equilibrium concentrations in sorption were analyzed by positive matrix factorization (PMF) to examine the factors underlying the leaching and sorption behavior of biochar. The identified factors can provide insightful understanding on experimental phenomena. Copyright © 2014 Elsevier Ltd. All rights reserved.

Sustainability evaluation of essential critical raw materials: cobalt, niobium, tungsten and rare earth elements

NASA Astrophysics Data System (ADS)

Tkaczyk, A. H.; Bartl, A.; Amato, A.; Lapkovskis, V.; Petranikova, M.

2018-05-01

The criticality of raw materials has become an important issue in recent years. As the supply of certain raw materials is essential for technologically-advanced economies, the European Commission and other international counterparts have started several initiatives to secure reliable and unhindered access to raw materials. Such efforts include the EU Raw Materials Initiative, European Innovation Partnership on Raw Materials, US Critical Materials Institute, and others. In this paper, the authors present a multi-faceted and multi-national review of the essentials for the critical raw materials (CRMs) Co, Nb, W, and rare earth elements (REEs). The selected CRMs are of specific interest as they are considered relevant for emerging technologies and will thus continue to be of increasing major economic importance. This paper presents a ‘sustainability evaluation’ for each element, including essential data about markets, applications and recycling, and possibilities for substitution have been summarized and analysed. All the presented elements are vital for the advanced materials and processes upon which modern societies rely. These elements exhibit superior importance in ‘green’ applications and products subject to severe conditions. The annual production quantities are quite low compared to common industrial metals. Of the considered CRMs, only Co and REE gross production exceed 100 000 t. At the same time, the prices are quite high, with W and Nb being in the range of 60 USD kg‑1 and some rare earth compounds costing almost 4000 USD kg‑1. Despite valiant effort, in practice some of the considered elements are de facto irreplaceable for many specialized applications, at today’s technological level. Often, substitution causes a significant loss of quality and performance. Furthermore, possible candidates for substitution may be critical themselves or available in considerably low quantities. It can be concluded that one preferred approach for the

Solvo-thermal synthesis of a unique alkaline earth-transition Ba-Cd micro-porous coordination framework as hetero-metallic luminescent sensor for Cu2+ and real-time detection of benzaldehyde

NASA Astrophysics Data System (ADS)

Ding, Bin; Ma, Dian Xue; Zhang, Hui Min; Meng, Xin; Qiu, Rong Rong; Ren, Rong; Wu, Jie; Wu, Xiang Xia; Huo, Jian Zhong; Liu, Yuan Yuan; Shi, Xue Fang

2018-06-01

In this work a unique hetero-metallic alkaline earth-transition Ba-Cd luminescent micro-porous metal-organic framework {[BaCd(μ6-tp)1.5(μ2-Cl)(H2O) (DMF)2]·0.75H2O}n (H2tp = terephthalic acid) (1) has been prepared under solvo-thermal conditions. In 1 infinite 1D {Ba-X-Cd} (X = O, Cl) inorganic chains are linked via these full de-pronated tp2- ligands forming a unique 3D I1O2 type micro-porous coordination framework. PXRD patterns of 1 have been determined confirming pure phases of 1. Luminescence investigations suggested that 1 exhibits highly selective and sensitive sensing for trace amounts of benzaldehyde in ethanol, which provides a facile method for real-time detection of benzaldehyde. Meanwhile 1 also exhibits highly selective and sensitive sensing for Cu2+ over other cations with high quenching efficiency Ksv value 1.15 × 104 L·mol-1. As far as we know, 1 represents the first example of alkaline earth-transition hetero-metallic Ba-Cd micro-porous coordination framework as bi-functional luminescent probes for Cu2+ and benzaldehyde.

Recycling of Rare Earth Elements

NASA Astrophysics Data System (ADS)

Lorenz, Tom; Bertau, Martin

2017-01-01

Any development of an effective process for rare earth (RE) recycling has become more and more challenging, especially in recent years. Since 2011, when commodity prices of REs had met their all-time maximum, prices have dropped rapidly by more than 90 %. An economic process able to offset these fluctuations has to take unconventional methods into account beside well-known strategies like acid/basic leaching or solvent extraction. The solid-state chlorination provides such an unconventional method for mobilizing RE elements from waste streams. Instead of hydrochloric acid this kind of chlorination decomposes NH4Cl thermally to release up to 400 °C hot HCl gas. After cooling the resulting solid metal chlorides may be easily dissolved in pH-adjusted water. Without producing strongly acidic wastes and with NH4Cl as cheap source for hydrogen chloride, solid-state chlorination provides various advantages in terms of costs and disposal. In the course of the SepSELSA project this method was examined, adjusted and optimized for RE recycling from fluorescent lamp scraps as well as Fe14Nd2B magnets. Thereby many surprising influences and trends required various analytic methods to examine the reasons and special mechanisms behind them.

Effect of alkaline earth metals on the liquid-phase hydrogenation of hydroquinone over Ru-based catalysts

NASA Astrophysics Data System (ADS)

Li, Hongwei; Ji, Dong; Li, Yu; Liang, Yalan; Li, Gui Xian

2015-12-01

A series of Ru-based catalysts modified by alkaline earth metals were prepared by the impregnation-precipitation method and characterized using transmission electron microscopy, X-ray diffraction, ICP optical emission spectroscopy, Infrared Spectroscopy of adsorbed pyridine analysis and surface area analysis. The performance of the catalysts was measured via liquid-phase hydroquinone hydrogenation reaction. Results show that the Ru-Sr/NaY catalyst has the best activity and selectivity among those Ru-based catalysts. The conversion of hydroquinone and the selectivity to 1,4-cyclohexanediol reached up to 99.6% and 89.6% at optimum reaction condition (700 r/min, 423 K and 5 MPa pressure of H2 in 3 h). This may be attributed to the fact that the right amount of Strontium is beneficial to the good dispersion of the ruthenium nanoclusters on the surface of NaY and modify the acidic properties of the catalyst. Moreover, IR of adsorbed pyridine analysis suggested the proper ratio of L/B acid of the catalysts played an important role in the performance of the hydroquinone hydrogenation reaction.

Preface to highly siderophile element constraints on Earth and planetary processes

NASA Astrophysics Data System (ADS)

Riches, Amy J. V.

2017-11-01

The geochemical properties of the highly siderophile elements (HSEs; Os, Ir, Ru, Rh, Pt, Pd, Re and Au) - being strongly iron-loving, but also chalcophile (i.e., having an affinity for sulphide), and generally occurring at ultra trace levels in silicate rocks, their weathered products, and oceanic waters - mean that this suite of elements and their isotopic compositions are useful in tracing a wide variety of processes. Thus, the HSEs are useful probes with which to tackle major research questions pertinent to past and present day change at a variety of scales and in a range of Earth and other-worldly environments by constraining reservoir compositions, chemical drivers, and the timing of key events and/or transformation rates.

Quantification of rare earth elements using laser-induced breakdown spectroscopy

DOE PAGES

Martin, Madhavi; Martin, Rodger C.; Allman, Steve; ...

2015-10-21

In this paper, a study of the optical emission as a function of concentration of laser-ablated yttrium (Y) and of six rare earth elements, europium (Eu), gadolinium (Gd), lanthanum (La), praseodymium (Pr), neodymium (Nd), and samarium (Sm), has been evaluated using the laser-induced breakdown spectroscopy (LIBS) technique. Statistical methodology using multivariate analysis has been used to obtain the sampling errors, coefficient of regression, calibration, and cross-validation of measurements as they relate to the LIBS analysis in graphite-matrix pellets that were doped with elements at several concentrations. Each element (in oxide form) was mixed in the graphite matrix in percentages rangingmore » from 1% to 50% by weight and the LIBS spectra obtained for each composition as well as for pure oxide samples. Finally, a single pellet was mixed with all the elements in equal oxide masses to determine if we can identify the elemental peaks in a mixed pellet. This dataset is relevant for future application to studies of fission product content and distribution in irradiated nuclear fuels. These results demonstrate that LIBS technique is inherently well suited for the future challenge of in situ analysis of nuclear materials. Finally, these studies also show that LIBS spectral analysis using statistical methodology can provide quantitative results and suggest an approach in future to the far more challenging multielemental analysis of ~ 20 primary elements in high-burnup nuclear reactor fuel.« less

Assessment of Bioavailable Concentrations of Germanium and Rare Earth Elements in the Rhizosphere of White Lupin (Lupinus albus L.)

NASA Astrophysics Data System (ADS)

Wiche, Oliver; Fischer, Ronny; Moschner, Christin; Székely, Balázs

2015-04-01

Concentrations of Germanium (Ge) and Rare Earth Elements in soils are estimated at 1.5 mg kg -1 (Ge), 25 mg kg -1 (La) and 20 mg kg -1 (Nd), which are only roughly smaller than concentrations of Pb and Zn. Germanium and rare earth elements are thus not rare but widely dispersed in soils and therefore up to date, only a few minable deposits are available. An environmental friendly and cost-effective way for Ge and rare earth element production could be phytomining. However, the most challenging part of a phytomining of these elements is to increase bioavailable concentrations of the elements in soils. Recent studies show, that mixed cultures with white lupine or other species with a high potential to mobilize trace metals in their rhizosphere due to an acidification of the soil and release of organic acids in the root zone could be a promising tool for phytomining. Complexation of Ge and rare earth elements by organic acids might play a key role in controlling bioavailability to plants as re-adsorption on soil particles and precipitation is prevented and thus, concentrations in the root zone of white lupine increase. This may also allow the complexes to diffuse along a concentration gradient to the roots of mixed culture growing species leading to enhanced plant uptake. However, to optimize mixed cultures it would be interesting to know to which extend mobilization of trace metals is dependent from chemical speciation of elements in soil due to the interspecific interaction of roots. A method for the identification of complexes of germanium and rare earth elements with organic acids, predominantly citric acid in the rhizosphere of white lupine was developed and successfully tested. The method is based on coupling of liquid chromatography with ICP-MS using a zic-philic column (SeQuant). As a preliminary result, we were able to show that complexes of germanium with citric acid exist in the rhizosphere of white lupin, what may contribute to the bioavailability of this

Modulation of Cardiac Ryanodine Receptor Channels by Alkaline Earth Cations

PubMed Central

Diaz-Sylvester, Paula L.; Porta, Maura; Copello, Julio A.

2011-01-01

Cardiac ryanodine receptor (RyR2) function is modulated by Ca2+ and Mg2+. To better characterize Ca2+ and Mg2+ binding sites involved in RyR2 regulation, the effects of cytosolic and luminal earth alkaline divalent cations (M2+: Mg2+, Ca2+, Sr2+, Ba2+) were studied on RyR2 from pig ventricle reconstituted in bilayers. RyR2 were activated by M2+ binding to high affinity activating sites at the cytosolic channel surface, specific for Ca2+ or Sr2+. This activation was interfered by Mg2+ and Ba2+ acting at low affinity M2+-unspecific binding sites. When testing the effects of luminal M2+ as current carriers, all M2+ increased maximal RyR2 open probability (compared to Cs+), suggesting the existence of low affinity activating M2+-unspecific sites at the luminal surface. Responses to M2+ vary from channel to channel (heterogeneity). However, with luminal Ba2+or Mg2+, RyR2 were less sensitive to cytosolic Ca2+ and caffeine-mediated activation, openings were shorter and voltage-dependence was more marked (compared to RyR2 with luminal Ca2+or Sr2+). Kinetics of RyR2 with mixtures of luminal Ba2+/Ca2+ and additive action of luminal plus cytosolic Ba2+ or Mg2+ suggest luminal M2+ differentially act on luminal sites rather than accessing cytosolic sites through the pore. This suggests the presence of additional luminal activating Ca2+/Sr2+-specific sites, which stabilize high Po mode (less voltage-dependent) and increase RyR2 sensitivity to cytosolic Ca2+ activation. In summary, RyR2 luminal and cytosolic surfaces have at least two sets of M2+ binding sites (specific for Ca2+ and unspecific for Ca2+/Mg2+) that dynamically modulate channel activity and gating status, depending on SR voltage. PMID:22039534

[Effects of rare earth elements on soil fauna community structure and their ecotoxicity to Holotrichia parallela].

PubMed

Li, Guiting; Jiang, Junqi; Chen, Jie; Zou, Yunding; Zhang, Xincai

2006-01-01

By the method of OECD filter paper contact, this paper studied the effects of applied rare earth elements on soil fauna community structure and their ecological toxicity to Holotrichia parallela in bean field. The results showed that there were no significant differences between the treatments and the control in soil fauna species, quantity of main species, and diversity index. Urgent and chronic toxic test showed that the differences between the treatments and the control were not significant. It was suggested that within the range of test dosages, rare earth elements had little ecological toxicity to Holotrichia parallela, and did not change the soil fauna community structure.

A chemical-spectrochemical method for the determination of rare earth elements and thorium in cerium minerals

USGS Publications Warehouse

Rose, H.J.; Murata, K.J.; Carron, M.K.

1954-01-01

In a combined chemical-spectrochemical procedure for quantitatively determining rare earth elements in cerium minerals, cerium is determined volumetrically, a total rare earths plus thoria precipitate is separated chemically, the ceria content of the precipitate is raised to 80??0 percent by adding pure ceria, and the resulting mixture is analyzed for lanthanum, praseodymium, neodymium, samarium, gadolinium, yttrium, and thorium spectrochemically by means of the d.c. carbon arc. Spectral lines of singly ionized cerium are used as internal standard lines in the spectrochemical determination which is patterned after Fassel's procedure [1]. Results of testing the method with synthetic mixtures of rare earths and with samples of chemically analyzed cerium minerals show that the coefficient of variation for a quadruplicate determination of any element does not exceed 5??0 (excepting yttrium at concentrations less than 1 percent) and that the method is free of serious systematic error. ?? 1954.

The Distribution of Heat-Producing Radioactive Elements in the Deep Earth

NASA Astrophysics Data System (ADS)

Chidester, Bethany A.

The Earth is a heat engine, where large differences in temperature between the interior and the surface drive large-scale movement that manifests as plate tectonics and the geomagnetic field that protects us from the Sun's harmful charged particles. Decay of the long-lived radioactive elements U, Th, and K is expected to contribute as much as 45% of the current heat production in the Earth, and that heat production was five times higher early in Earth's history. It is unclear how this heat source affects the thermal and dynamic evolution of the Earth's core and mantle and how that contribution has changed over geologic time. This dissertation addresses this problem in several different ways. This work represents the first high-pressure, high-temperature metal-silicate partitioning experiments for U, Th, and K in the laser-heated diamond anvil cell at conditions relevant to core formation. A chemical model is developed using parameterization of these partitioning data to constrain the concentrations of each of these elements in the core. Using a numerical calculation, it is then determined how that radioactive heat would contribute to the core's energy and entropy budget through time. One finds that, despite its strong lithophile nature at the surface, U partitions significantly into the metallic phase at increasing temperatures. This may be due to a decrease in U valence from 4+ to 2+ in high-pressure silicate melts, which our data supports. However, K and Th do not exhibit a similar change in behavior at these conditions, and this may drive fractionation between U and Th in the deep mantle. At the most extreme conditions of core formation, enough U could exist in the core to produce up to 4.4 TW of heat 4.5 billion years ago. Potassium could produce much less heat than U early on (< 1 TW), and due to its short half-life, would have decayed away much faster. While this energy source is significantly greater than was previously thought to be possible, it is likely

Survey of the class of isovalent antiperovskite alkaline-earth pnictide compounds

NASA Astrophysics Data System (ADS)

Goh, Wen Fong; Pickett, Warren E.

2018-01-01

The few reported members of the antiperovskite structure class A e3P nAP nB of alkaline-earth (A e =Ca , Sr, Ba) pnictide (P n =N , P, As, Sb, Bi) compounds are all based on the B -site anion P nB=N . All can be categorized as narrow-gap semiconductors, making them of interest for several reasons. Because chemical reasoning suggests that more members of this class may be stable, we provide here a density functional theory (DFT)-based survey of this entire class of 3 ×5 ×5 compounds. We determine first the relative energetic stability of the distribution of pairs of P n ions in the A and B sites of the structure, finding that the B site always favors the small pnictogen anion. The trends of the calculated energy gaps versus the A e cation and P n anions are determined, and we study effects of spin-orbit coupling as well as two types of gap corrections to the conventional DFT electronic spectrum. Because there have been suggestions that this class harbors topological insulating phases, we have given this possibility attention and found that energy gap corrections indicate the cubic structures will provide at most a few topological insulators. Structural instability is addressed by calculating phonon dispersion curves for a few compounds, with one outcome being that distorted structures should be investigated further for thermoelectric and topological character. Examples of the interplay between spin-orbit coupling and strain on the topological nature are provided. A case study of Ca3BiP including the effect of strain illustrates how a topological semimetal can be transformed into a topological insulator and Dirac semimetal.

Composition of the earth's upper mantle. II - Volatile trace elements in ultramafic xenoliths

NASA Technical Reports Server (NTRS)

Morgan, J. W.; Wandless, G. A.; Petrie, R. K.; Irving, A. J.

1980-01-01

Radiochemical neutron activation analysis was used to determine the nine volatile elements Ag, Bi, Cd, In, Sb, Se, Te, Tl, and Zn in 19 ultramafic rocks, consisting mainly of spinel and garnet lherzolites. A sheared garnet lherzolite, PHN 1611, may approximate undepleted mantle material and tends to have a higher volatile element content than the depleted mantle material represented by spinel lherzolites. Comparisons of continental basalts with PHN 1611 and of oceanic ridge basalts with spinel lherzolites show similar basalt: source material partition factors for eight of the nine volatile elements, Sb being the exception. The strong depletion of Te and Se in the mantle, relative to lithophile elements of similar volatility, suggests that 97% of the earth's S, Se and Te may be in the outer core.

[Indirect determination of rare earth elements in Chinese herbal medicines by hydride generation-atomic fluorescence spectrometry].

PubMed

Zeng, Chao; Lu, Jian-Ping; Xue, Min-Hua; Tan, Fang-Wei; Wu, Xiao-Yan

2014-07-01

Based on their similarity in chemical properties, rare earth elements were able to form stable coordinated compounds with arsenazo III which were extractable into butanol in the presence of diphenylguanidine. The butanol was removed under reduced pressure distillation; the residue was dissolved with diluted hydrochloric acid. As was released with the assistance of KMnO4 and determined by hydrogen generation-atomic fluorescence spectrometry in terms of rare earth elements. When cesium sulfate worked as standard solution, extraction conditions, KMnO4 amount, distillation temperature, arsenazo III amount, interfering ions, etc were optimized. The accuracy and precision of the method were validated using national standard certified materials, showing a good agreement. Under optimum condition, the linear relationship located in 0.2-25 microg x mL(-1) and detection limit was 0.44 microg x mL(-1). After the herbal samples were digested with nitric acid and hydrogen peroxide, the rare earth elements were determined by this method, showing satisfactory results with relative standard deviation of 1.3%-2.5%, and recoveries of 94.4%-106.0%. The method showed the merits of convenience and rapidness, simple instrumentation and high accuracy. With the rare earths enriched into organic phase, the separation of analytes from matrix was accomplished, which eliminated the interference. With the residue dissolved by diluted hydrochloric acid after the solvent was removed, aqueous sample introduction eliminated the impact of organic phase on the tubing connected to pneumatic pump.

Catalytic Diversity in Alkaline Hydrothermal Vent Systems on Ocean Worlds

NASA Astrophysics Data System (ADS)

Cameron, Ryan D.; Barge, Laura; Chin, Keith B.; Doloboff, Ivria J.; Flores, Erika; Hammer, Arden C.; Sobron, Pablo; Russell, Michael J.; Kanik, Isik

2016-10-01

Hydrothermal systems formed by serpentinization can create moderate-temperature, alkaline systems and it is possible that this type of vent could exist on icy worlds such as Europa which have water-rock interfaces. It has been proposed that some prebiotic chemistry responsible for the emergence of life on Earth and possibly other wet and icy worlds could occur as a result ofredox potential and pH gradients in submarine alkaline hydrothermal vents (Russell et al., 2014). Hydrothermal chimneys formed in laboratory simulations of alkaline vents under early Earth conditions have precipitate membranes that contain minerals such as iron sulfides, which are hypothesized to catalyze reduction of CO2 (Yamaguchi et al. 2014, Roldan et al. 2014) leading to further organic synthesis. This CO2 reduction process may be affected by other trace components in the chimney, e.g. nickel or organic molecules. We have conducted experiments to investigate catalytic properties of iron and iron-nickel sulfides containing organic dopants in slightly acidic ocean simulants relevant to early Earth or possibly ocean worlds. We find that the electrochemical properties of the chimney as well as the morphology/chemistry of the precipitate are affected by the concentration and type of organics present. These results imply that synthesis of organics in water-rock systems on ocean worlds may lead to hydrothermal precipitates which can incorporate these organic into the mineral matrix and may affect the role of gradients in alkaline vent systems.Therefore, further understanding on the electroactive roles of various organic species within hydrothermal chimneys will have important implications for habitability as well as prebiotic chemistry. This work is funded by NASA Astrobiology Institute JPL Icy Worlds Team and a NAI Director's Discretionary Fund award.Yamaguchi A. et al. (2014) Electrochimica Acta, 141, 311-318.Russell, M. J. et al. (2014), Astrobiology, 14, 308-43.Roldan, A. (2014) Chem. Comm. 51

Substitution of Nd with other rare earth elements in melt spun Nd{sub 2}Fe{sub 14}B magnets

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

Brown, D. N.; Lau, D.; Chen, Z.

2016-05-15

This is a contemporary study of rapidly quenched Nd{sub 1.6}X{sub 0.4}Fe{sub 14}B magnetic materials (where X= Nd, Y, Ce, La, Pr, Gd and Ho). A 20% substitution of the Nd component from Nd{sub 2}Fe{sub 14}B can bring about some commercial advantage. However, there will be some compromise to the magnetic performance. Light rare earth elements are definitely more abundant (Y, Ce, La) than the heavier rare earth elements, but when they are included in RE{sub 2}Fe{sub 14}B magnets they tend to lower magnetic performance and thermal stability. Substituting heavy rare earth elements (Gd, Ho) for Nd in Nd{sub 2}Fe{sub 14}Bmore » improves the thermal stability of magnets but causes a loss in magnet remanence.« less

Rare earth element and rare metal inventory of central Asia

USGS Publications Warehouse

Mihalasky, Mark J.; Tucker, Robert D.; Renaud, Karine; Verstraeten, Ingrid M.

2018-03-06

Rare earth elements (REE), with their unique physical and chemical properties, are an essential part of modern living. REE have enabled development and manufacture of high-performance materials, processes, and electronic technologies commonly used today in computing and communications, clean energy and transportation, medical treatment and health care, glass and ceramics, aerospace and defense, and metallurgy and chemical refining. Central Asia is an emerging REE and rare metals (RM) producing region. A newly compiled inventory of REE-RM-bearing mineral occurrences and delineation of areas-of-interest indicate this region may have considerable undiscovered resources.

Determination of rare-earth elements in Luna 16 regolith sample by chemical spectral method

NASA Technical Reports Server (NTRS)

Stroganova, N. S.; Ryabukhin, V. A.; Laktinova, N. V.; Ageyeva, L. V.; Galkina, I. P.; Gatinskaya, N. G.; Yermakov, A. N.; Karyakin, A. V.

1974-01-01

An analysis was made of regolith from layer A of the Luna 16 sample for rare earth elements, by a chemical spectral method. Chemical and ion exchange concentrations were used to determine the content of 12 elements and Y at the level 0.001 to 0.0001 percent with 10 to 15 percent reproducibility of the emission determination. Results within the limits of reproducibility agree with data obtained by mass spectra, activation, and X-ray fluorescent methods.

Dissolved Rare Earth Elements in the US GEOTRACES North Atlantic Section

NASA Astrophysics Data System (ADS)

Shiller, A. M.

2016-12-01

The rare earth elements (REEs) are a unique chemical set wherein there are systematic changes in geochemical behavior across the series. Furthermore, while most REEs are in the +III oxidation state, Ce and Eu can be in other oxidation states leading to distinct characteristics of those elements. Thus, the geochemical properties of the REEs make them particularly useful tools for inquiring into various geochemical processes. As part of the US GEOTRACES effort, we determined dissolved REEs and Y at 32 stations across the North Atlantic during US cruises GT10 and GT11 along a meridional transect from Lisbon to the Cape Verde Islands and a zonal transect from Cape Cod to the Mauritanian coast. While profiles are similar to previous reports, the high spatial resolution of the section allows for better elucidation of processes. Light rare earths (LREEs) show removal in the upper water column with a minimum at the chlorophyll maximum. LREE concentrations then increase into the oxygen minimum followed by a slight decrease and fairly constant concentrations in the mid-water column followed by an increase into the deep and bottom waters. Heavy rare earths (HREEs) show a more monotonic increase with depth. We also take advantage of a previously published water mass analysis for the section to estimate that most of the deep water changes can be explained by conservative mixing of waters with different pre-formed REE concentrations. Nonetheless, the pattern of LREE shallow water removal followed by regeneration, possible re-scavenging, and then deep water input is still preserved. Other features of note include an increase in LREEs in the strong oxygen minimum zone off Mauritania, consistent with an association of REE cycling with the redox cycles of Fe and Mn. Also along the eastern margin, but below the oxygen minimum, a small but distinct increase in the cerium and europium anomalies is observed, consistent with terrigenous input. In hydrothermally influenced waters along

Determination of rare earth elements concentration at different depth profile of Precambrian pegmatites using instrumental neutron activation analysis.

PubMed

Sadiq Aliyu, Abubakar; Musa, Yahaya; Liman, M S; Abba, Habu T; Chaanda, Mohammed S; Ngene, Nnamani C; Garba, N N

2018-01-01

The Keffi area hosts abundant pegmatite bodies as a result of the surrounding granitic intrusions. Keffi is part of areas that are geologically classified as North Central Basement Complex. Data on the mineralogy and mineralogical zonation of the Keffi pegmatite are scanty. Hence the need to understand the geology and mineralogical zonation of Keffi pegmatites especially at different depth profiles is relevant as a study of the elemental composition of the pegmatite is essential for the estimation of its economic viability. Here, the relative standardization method of instrumental neutron activation analysis (INAA) has been used to investigate the vertical deviations of the elemental concentrations of rare earth elements (REEs) at different depth profile of Keffi pegmatite. This study adopted the following metrics in investigating the vertical variations of REEs concentrations. Namely, the total contents of rare earth elements (∑REE); ratio of light to heavy rare earth elements (LREE/HREE), which defines the enrichment or depletion of REEs; europium anomaly (Eu/Sm); La/Lu ratio relative to chondritic meteorites. The study showed no significant variations in the total content of rare elements between the vertical depth profiles (100-250m). However, higher total concentrations of REEs (~ 92.65ppm) were recorded at the upper depth of the pegmatite and the europium anomaly was consistently negative at all the depth profiles suggesting that the Keffi pegmatite is enriched with light REEs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chromatographic Techniques for Rare Earth Elements Analysis

NASA Astrophysics Data System (ADS)

Chen, Beibei; He, Man; Zhang, Huashan; Jiang, Zucheng; Hu, Bin

2017-04-01

The present capability of rare earth element (REE) analysis has been achieved by the development of two instrumental techniques. The efficiency of spectroscopic methods was extraordinarily improved for the detection and determination of REE traces in various materials. On the other hand, the determination of REEs very often depends on the preconcentration and separation of REEs, and chromatographic techniques are very powerful tools for the separation of REEs. By coupling with sensitive detectors, many ambitious analytical tasks can be fulfilled. Liquid chromatography is the most widely used technique. Different combinations of stationary phases and mobile phases could be used in ion exchange chromatography, ion chromatography, ion-pair reverse-phase chromatography and some other techniques. The application of gas chromatography is limited because only volatile compounds of REEs can be separated. Thin-layer and paper chromatography are techniques that cannot be directly coupled with suitable detectors, which limit their applications. For special demands, separations can be performed by capillary electrophoresis, which has very high separation efficiency.

Geophysical Framework of a Rare Earth Element Enriched Terrane, Mountain Pass, California

NASA Astrophysics Data System (ADS)

Denton, K. M.; Ponce, D. A.; Peacock, J.; Miller, D. M.; Miller, J. S.

2016-12-01

Carbonatite ore deposits continue to be the primary source for rare earth elements (REEs), however large viable REE ore deposits are uncommon. The Mountain Pass carbonatite deposit, located in the eastern Mojave Desert of California, is the largest economic deposit of light REEs in North America. A 1.417 Ga ultrapotassic suite (shonkinite, syenite, and granite) and a 1.375 Ga barite-bastnasite-rich carbonatite (sovite) ore deposit comprise the enclave of REE-enriched outcrops and dikes that occupy a narrow ( 3 km) zone of 1.7 Ga gneiss extending at least 10-km to the southeast from southern Clark Mountain. Modeling of gravity, magnetic, and magnetotelluric (MT) data reveals subsurface features that form the structural framework of the REE terrane. The carbonatite and ultrapotassic mafic suite is associated with a local gravity high that is superimposed on a 4 km-wide gravity terrace, likely related to less dense granitic gneiss basement. Although physical property data indicate that the intrusive suite and carbonatite are essentially and nonmagnetic, aeromagnetic data indicate that these rocks occur along the eastern edge of a prominent north-northwest trending aeromagnetic high. This relationship suggests that they may have been preferentially emplaced along a zone of weakness or fault. The source of the magnetic high is 2-3 km below the surface and coincides with a relatively electrically conductive (3 orders of magnitude higher than surrounding rock) feature. MT data indicate that the western edge of the magnetic feature could be connected to a deeper ( 8 km) conductive feature related to possible intrusions and/or hydrothermal systems. The lack of a magnetic signature of the REE terrane can be explained by alteration of magnetite, given that the terrane lies within a broader alteration zone and observed magnetic low. If so, such an alteration event, capable of remobilizing rare earth elements, likely occurred during or after emplacement of the intrusive suite

Fluid rare earth element anlayses from wells RN-12 and RN-19, Reykjanes, Iceland

DOE Data Explorer

Andrew Fowler

2015-07-24

Results for fluid rare earth elment analyses from Reykjanes wells RN-12 and RN-19. The data have not been corrected for flashing. Samples preconcetrated using chelating resin with IDA functional group (InertSep ME-1). Analyzed using and Element magnetic sctor ICP-MS.

Effect of certain alkaline metals on Pr doped glasses to investigate spectroscopic studies

NASA Astrophysics Data System (ADS)

Lenkennavar Susheela, K.; Madhu, A.; Eraiah, B.; Kokila, M. K.

2018-02-01

Incorporation of different Alkaline earth metal like Barium, Calcium and strontium in sodium lead borate glass doped with Pr3+ is studied. Physical parameters such as density, molar volume, molar refractivity etc have been evaluated. Effect of different atomic size of alkaline metal using optical and physical parameters is analysed. XRD and FTIR were carried out to know the structural behaviour of the glasses. Absorption and Emission spectra are recorded at room temperature and the results were discussed.

Carbon cycling and snowball Earth.

PubMed

Goddéris, Yves; Donnadieu, Yannick

2008-12-18

The possibility that Earth witnessed episodes of global glaciation during the latest Precambrian challenges our understanding of the physical processes controlling the Earth's climate. Peltier et al. suggest that a 'hard snowball Earth' state may have been prevented owing to the release of CO(2) from the oxidation of dissolved organic carbon (DOC) in the ocean as the temperature decreased. Here we show that the model of Peltier et al. is not self-consistent as it implies large fluctuations of the ocean alkalinity content without providing any processes to account for it. Our findings suggest that the hard snowball Earth hypothesis is still valid.

Solvo-thermal synthesis of a unique alkaline earth-transition Ba-Cd micro-porous coordination framework as hetero-metallic luminescent sensor for Cu2+ and real-time detection of benzaldehyde.

PubMed

Ding, Bin; Ma, Dian Xue; Zhang, Hui Min; Meng, Xin; Qiu, Rong Rong; Ren, Rong; Wu, Jie; Wu, Xiang Xia; Huo, Jian Zhong; Liu, Yuan Yuan; Shi, Xue Fang

2018-06-15

In this work a unique hetero-metallic alkaline earth-transition Ba-Cd luminescent micro-porous metal-organic framework {[BaCd(μ 6 -tp) 1.5 (μ 2 -Cl)(H 2 O) (DMF) 2 ]·0.75H 2 O} n (H 2 tp=terephthalic acid) (1) has been prepared under solvo-thermal conditions. In 1 infinite 1D {Ba-X-Cd} (X=O, Cl) inorganic chains are linked via these full de-pronated tp 2- ligands forming a unique 3D I 1 O 2 type micro-porous coordination framework. PXRD patterns of 1 have been determined confirming pure phases of 1. Luminescence investigations suggested that 1 exhibits highly selective and sensitive sensing for trace amounts of benzaldehyde in ethanol, which provides a facile method for real-time detection of benzaldehyde. Meanwhile 1 also exhibits highly selective and sensitive sensing for Cu 2+ over other cations with high quenching efficiency K sv value 1.15×10 4 L·mol -1 . As far as we know, 1 represents the first example of alkaline earth-transition hetero-metallic Ba-Cd micro-porous coordination framework as bi-functional luminescent probes for Cu 2+ and benzaldehyde. Copyright © 2018 Elsevier B.V. All rights reserved.

Decomposition of diverse solid inorganic matrices with molten ammonium bifluoride salt for constituent elemental analysis

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

O'Hara, Matthew J.; Kellogg, Cyndi M.; Parker, Cyrena M.

Ammonium bifluoride (ABF, NH4F·HF) is a well-known reagent for converting metal oxides to fluorides and for its applications in breaking down minerals and ores in order to extract useful components. It has been more recently applied to the decomposition of inorganic matrices prior to elemental analysis. Herein, a sample decomposition method that employs molten ABF sample treatment in the initial step is systematically evaluated across a range of inorganic sample types: glass, quartz, zircon, soil, and pitchblende ore. Method performance is evaluated across the two variables: duration of molten ABF treatment and ABF reagent mass to sample mass ratio. Themore » degree of solubilization of these sample classes are compared to the fluoride stoichiometry that is theoretically necessary to enact complete fluorination of the sample types. Finally, the sample decomposition method is performed on several soil and pitchblende ore standard reference materials, after which elemental constituent analysis is performed by ICP-OES and ICP-MS. Elemental recoveries are compared to the certified values; results indicate good to excellent recoveries across a range of alkaline earth, rare earth, transition metal, and actinide elements.« less

Mimicking the magnetic properties of rare earth elements using superatoms.

PubMed

Cheng, Shi-Bo; Berkdemir, Cuneyt; Castleman, A W

2015-04-21

Rare earth elements (REs) consist of a very important group in the periodic table that is vital to many modern technologies. The mining process, however, is extremely damaging to the environment, making them low yield and very expensive. Therefore, mimicking the properties of REs in a superatom framework is especially valuable but at the same time, technically challenging and requiring advanced concepts about manipulating properties of atom/molecular complexes. Herein, by using photoelectron imaging spectroscopy, we provide original idea and direct experimental evidence that chosen boron-doped clusters could mimic the magnetic characteristics of REs. Specifically, the neutral LaB and NdB clusters are found to have similar unpaired electrons and magnetic moments as their isovalent REs (namely Nd and Eu, respectively), opening up the great possibility in accomplishing rare earth mimicry. Extension of the superatom concept into the rare earth group not only further shows the power and advance of this concept but also, will stimulate more efforts to explore new superatomic clusters to mimic the chemistry of these heavy atoms, which will be of great importance in designing novel building blocks in the application of cluster-assembled nanomaterials. Additionally, based on these experimental findings, a novel "magic boron" counting rule is proposed to estimate the numbers of unpaired electrons in diatomic LnB clusters.

Rare earth element mineralogy, geochemistry, and preliminary resource assessment of the Khanneshin carbonatite complex, Helmand Province, Afghanistan

USGS Publications Warehouse

Tucker, Robert D.; Belkin, Harvey E.; Schulz, Klaus J.; Peters, Stephen G.; Buttleman, Kim P.

2011-01-01

There is increased concern about the future availability of rare earth elements (REE) because of China's dominance as the supplier of more than 95 percent of world REE output, their decision to restrict exports of rare earth products, and the rapid increase in world-wide consumption of rare earth product. As a result, countries such as the United States, Japan, and member nations of the European Union face a future of tight supplies and high prices for rare earth products unless other sources of REE are found and developed (Long and others, 2010; U.S. Geological Survey, 2011, p. 128-129, 184-185). We report and describe a significant new deposit of light rare earth elements (LREE), estimated at 1 Mt, within the Khanneshin carbonatite complex of south Afghanistan. The potential resource is located in a remote and rugged part of the igneous complex in a region previously identified by Soviet geologists in the 1970s. This report reviews the geologic setting of LREE deposit, presents new geochemical data documenting the grade of LREE mineralization, briefly describes the mineralogy and mineralogical associations of the deposit, and presents a preliminary estimate of LREE resources based on our current understanding of the geology.

Rationally designed mineralization for selective recovery of the rare earth elements

NASA Astrophysics Data System (ADS)

Hatanaka, Takaaki; Matsugami, Akimasa; Nonaka, Takamasa; Takagi, Hideki; Hayashi, Fumiaki; Tani, Takao; Ishida, Nobuhiro

2017-05-01

The increasing demand for rare earth (RE) elements in advanced materials for permanent magnets, rechargeable batteries, catalysts and lamp phosphors necessitates environmentally friendly approaches for their recovery and separation. Here, we propose a mineralization concept for direct extraction of RE ions with Lamp (lanthanide ion mineralization peptide). In aqueous solution containing various metal ions, Lamp promotes the generation of RE hydroxide species with which it binds to form hydrophobic complexes that accumulate spontaneously as insoluble precipitates, even under physiological conditions (pH ~6.0). This concept for stabilization of an insoluble lanthanide hydroxide complex with an artificial peptide also works in combination with stable scaffolds like synthetic macromolecules and proteins. Our strategy opens the possibility for selective separation of target metal elements from seawater and industrial wastewater under mild conditions without additional energy input.

Rationally designed mineralization for selective recovery of the rare earth elements.

PubMed

Hatanaka, Takaaki; Matsugami, Akimasa; Nonaka, Takamasa; Takagi, Hideki; Hayashi, Fumiaki; Tani, Takao; Ishida, Nobuhiro

2017-05-26

The increasing demand for rare earth (RE) elements in advanced materials for permanent magnets, rechargeable batteries, catalysts and lamp phosphors necessitates environmentally friendly approaches for their recovery and separation. Here, we propose a mineralization concept for direct extraction of RE ions with Lamp (lanthanide ion mineralization peptide). In aqueous solution containing various metal ions, Lamp promotes the generation of RE hydroxide species with which it binds to form hydrophobic complexes that accumulate spontaneously as insoluble precipitates, even under physiological conditions (pH ∼6.0). This concept for stabilization of an insoluble lanthanide hydroxide complex with an artificial peptide also works in combination with stable scaffolds like synthetic macromolecules and proteins. Our strategy opens the possibility for selective separation of target metal elements from seawater and industrial wastewater under mild conditions without additional energy input.

Enhancing Kondo coupling in alkaline-earth-metal atomic gases with confinement-induced resonances in mixed dimensions

NASA Astrophysics Data System (ADS)

Cheng, Yanting; Zhang, Ren; Zhang, Peng; Zhai, Hui

2017-12-01

The Kondo effect describes the spin-exchange interaction between localized impurities and itinerant fermions. The ultracold alkaline-earth atomic gas provides a natural platform for quantum simulation of the Kondo model, utilizing its long-lived clock state and the nuclear-spin exchange interaction between clock state and ground state. One of the key issue now is whether the Kondo temperature can be high enough to be reached in current experiments, for which we have proposed to use transverse confinement to confine atoms into a one-dimensional tube and to use the confinement-induced resonance to enhance Kondo coupling. In this work, we further consider the (1 +0 ) -dimensional scattering problem when the clock state is further confined by an axial harmonic confinement. We show that this axial confinement for the clock-state atoms not only plays a role for localizing them, but can also act as an additional control knob to reach the confinement-induced resonance. We show that, in the presence of both the transverse and the axial confinements, the confinement-induced resonance can be reached in the practical conditions and the Kondo effect can be attainable in this system.

Theoretical Studies of the Spin Hamiltonian Parameters and Local Distortions for Cu2+ in Alkaline Earth Lead Zinc Phosphate Glasses

NASA Astrophysics Data System (ADS)

Wang, Bo-Kun; Wu, Shao-Yi; Yuan, Zi-Yi; Liu, Zi-Xuan; Jiang, Shi-Xin; Liu, Zheng; Yao, Zi-Jian; Teng, Bao-Hua; Wu, Ming-He

2016-08-01

The spin Hamiltonian parameters and local structures are theoretically studied for Cu2+-doped alkaline earth lead zinc phosphate (RPPZ, R=Mg, Ca, Sr, and Ba) glasses based on the high-order perturbation calculations for a tetragonally elongated octahedral 3d9 cluster. The relative elongation ratios are found to be ρ≈3.2%, 4.4%, 4.6%, and 3.3% for R=Mg, Ca, Sr, and Ba, respectively, because of the Jahn-Teller effect. The whole decreasing crystal-field strength Dq and orbital reduction factor k from Mg to Sr are ascribed to the weakening electrostatic coulombic interactions and the increasing probability of productivity of nonbridge oxygen (and hence increasing Cu2+-O2- electron cloud admixtures) under PbO addition, respectively, with increasing alkali earth ionic radius. The anomalies (the largest Dq and the next highest k among the systems) for R=Ba are attributed to the cross linkage of this large cation in the network. The overall increasing order (Mg≤Ba

Realizing the therapeutic potential of rare earth elements in designing nanoparticles to target and treat glioblastoma.

PubMed

Lu, Victor M; McDonald, Kerrie L; Townley, Helen E

2017-10-01

The prognosis of brain cancer glioblastoma (GBM) is poor, and despite intense research, there have been no significant improvements within the last decade. This stasis implicates the need for more novel therapeutic investigation. One such option is the use of nanoparticles (NPs), which can be beneficial due to their ability to penetrate the brain, overcome the blood-brain barrier and take advantage of the enhanced permeation and retention effect of GBM to improve specificity. Rare earth elements possess a number of interesting natural properties due to their unique electronic configuration, which may prove therapeutically advantageous in an NP formulation. The underexplored exciting potential for rare earth elements to augment the therapeutic potential of NPs in GBM treatment is discussed in this review.

Rare earth element content of cryptocrystalline magnesites of Konya, Turkey

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

Zedef, Veysel, E-mail: vzedef@selcuk.edu.tr; Russell, Michael

We examined the rare earth element content of several cryptocrystalline magnesites as well as hydromagnesite, host rock serpentinites, lake water and hot spring water from Turkey. Southwestern Turkey hosts cryptocrystalline magnesites, sedimentary magnesites with presently forming, biologically mediated hydromagnesites and travertines. Our results show the REE content of the minerals, rocks and waters are well below detection limits. One hydromagnesite sample from Lake Salda has slightly high La (2.38ppb), Ce (3.91 ppb) and Nd (1.68 ppb) when compared to other samples, but these are also still below detection limits of the method we followed.

Geochemical fractions of rare earth elements in soil around a mine tailing in Baotou, China

PubMed Central

Wang, Lingqing; Liang, Tao

2015-01-01

Rare earth mine tailing dumps are environmental hazards because tailing easily leaches and erodes by water and wind. To assess the influence of mine tailing on the geochemical behavior of rare earth elements (REEs) in soil, sixty-seven surface soil samples and three soil profile samples were collected from different locations near China’s largest rare earth mine tailing. The total concentration of REEs in surface soils ranged from 156 to 5.65 × 104 mg·kg−1 with an average value of 4.67 × 103 mg·kg−1, which was significantly higher than the average value in China (181 mg·kg−1). We found obvious fractionation of both light and heavy REEs, which was supported by the North American Shale Composite (NASC) and the Post-Archean Average Australian Shale (PAAS) normalized concentration ratios calculated for selected elements (LaN/YbN, LaN/SmN and GdN/YbN). A slightly positive Ce anomaly and a negative Eu anomaly were also found. For all 14 REEs in soils, enrichment was intensified by the mine tailing sources and influenced by the prevailing wind. PMID:26198417

Geochemical fractions of rare earth elements in soil around a mine tailing in Baotou, China.

PubMed

Wang, Lingqing; Liang, Tao

2015-07-22

Rare earth mine tailing dumps are environmental hazards because tailing easily leaches and erodes by water and wind. To assess the influence of mine tailing on the geochemical behavior of rare earth elements (REEs) in soil, sixty-seven surface soil samples and three soil profile samples were collected from different locations near China's largest rare earth mine tailing. The total concentration of REEs in surface soils ranged from 156 to 5.65 × 10(4) mg·kg(-1) with an average value of 4.67 × 10(3) mg·kg(-1), which was significantly higher than the average value in China (181 mg·kg(-1)). We found obvious fractionation of both light and heavy REEs, which was supported by the North American Shale Composite (NASC) and the Post-Archean Average Australian Shale (PAAS) normalized concentration ratios calculated for selected elements (La(N)/Yb(N), La(N)/Sm(N) and Gd(N)/Yb(N)). A slightly positive Ce anomaly and a negative Eu anomaly were also found. For all 14 REEs in soils, enrichment was intensified by the mine tailing sources and influenced by the prevailing wind.

Development of New Cementitious Caterials by Alkaline Activating Industrial by-Products

NASA Astrophysics Data System (ADS)

Fernández-Jimenez, A.; García-Lodeiro, I.; Palomo, A.

2015-11-01

The alkaline activation of aluminosiliceous industrial by-products such as blast furnace slag and fly ash is widely known to yield binders whose properties make them comparable to or even stronger and more durable than ordinary Portland cement. The present paper discusses activation fundamentals (such as the type and concentration of alkaline activator and curing conditions) as well as the structure of the cementitious gels formed (C-A-S-H, N-A-S-H). The durability and strength of these systems make these materials apt for use in many industrial applications, such as precast concrete elements (masonery blocks, railroad sleepers), protective coatings for materials with low fire ratings and lightweight elements.

The Not-So-Rare Earths.

ERIC Educational Resources Information Center

Muecke, Gunter K.; Moller, Peter

1988-01-01

Describes the characteristics of rare earth elements. Details the physical chemistry of rare earths. Reviews the history of rare earth chemistry and mineralogy. Discusses the mineralogy and crystallography of the formation of rare earth laden minerals found in the earth's crust. Characterizes the geologic history of rare earth elements. (CW)

Modeling viscoelastic deformation of the earth due to surface loading by commercial finite element package - ABAQUS

NASA Astrophysics Data System (ADS)

Kit Wong, Ching; Wu, Patrick

2017-04-01

Wu (2004) developed a transformation scheme to model viscoelatic deformation due to glacial loading by commercial finite element package - ABAQUS. Benchmark tests confirmed that this method works extremely well on incompressible earth model. Bangtsson & Lund (2008),however, showed that the transformation scheme would lead to incorrect results if compressible material parameters are used. Their study implies that Wu's method of stress transformation is inadequate to model the load induced deformation of a compressible earth under the framework of ABAQUS. In light of this, numerical experiments are carried out to find if there exist other methods that serve this purpose. All the tested methods are not satisfying as the results failed to converge through iterations, except at the elastic limit. Those tested methods will be outlined and the results will be presented. Possible reasons of failure will also be discussed. Bängtsson, E., & Lund, B. (2008). A comparison between two solution techniques to solve the equations of glacially induced deformation of an elastic Earth. International journal for numerical methods in engineering, 75(4), 479-502. Wu, P. (2004). Using commercial finite element packages for the study of earth deformations, sea levels and the state of stress. Geophysical Journal International, 158(2), 401-408.

Preliminary study on using rare earth elements to trace non-point source phosphorous loss

USDA-ARS?s Scientific Manuscript database

The environmental fate of phosphorus (P) is of concern as P is a primary cause of freshwater eutrophication. Rare earth elements (REEs) have been successfully used in the analysis of soil erosion and pollutant sources, as well as in the analysis of mineral genesis. To better understand the potential...

[Effects of arbuscular mycorrhizal fungi on the growth and rare earth elements uptake of soybean grown in rare earth mine tailings].

PubMed

Guo, Wei; Zhao, Ren-xin; Zhao, Wen-jing; Fu, Rui-ying; Guo, Jiang-yuan; Zhang, Jun

2013-05-01

A greenhouse pot experiment was conducted to investigate the influence of arbuscular mycorrhizal (AM) fungi Glomus versiforme on the plant growth, nutrient uptake, C: N: P stoichiometric, uptake of heavy metals and rare earth elements by soybean (Glycine max) grown in rare earth mine tailings. The aim was to provide a basis for the revegetation of rare earth mine tailings. The results indicated that soybean had a high mycorrhizal colonization and symbiotic associations were successfully established with G. versiforme, with an average rate of approximately 67%. The colonization of G. versiforme significantly promoted the growth of soybean, increased P, K contents, and decreased C: N: P ratios, supporting the growth rate hypothesis. Inoculation with G. versiforme significantly decreased shoots and roots La, Ce, Pr and Nd concentrations of soybean compared to the control treatment. However, inoculation with G. versiforme had no significant effect on the heavy metal concentrations, except for significantly decreased shoot Fe and Cr concentrations and increased root Cd concentrations. The experiment demonstrates that AM fungi have a potential role for soybean to adapt the composite adversity of rare earth tailings and play a positive role in revegetation of rare earth mine tailings. Further studies on the role of AM fungi under natural conditions should be conducted.

Identification of a Retroelement from the Resurrection Plant Boea hygrometrica That Confers Osmotic and Alkaline Tolerance in Arabidopsis thaliana

PubMed Central

Shen, Chun-Ying; Xu, Guang-Hui; Chen, Shi-Xuan; Song, Li-Zhen; Li, Mei-Jing; Wang, Li-Li; Zhu, Yan; Lv, Wei-Tao; Gong, Zhi-Zhong; Liu, Chun-Ming; Deng, Xin

2014-01-01

Functional genomic elements, including transposable elements, small RNAs and non-coding RNAs, are involved in regulation of gene expression in response to plant stress. To identify genomic elements that regulate dehydration and alkaline tolerance in Boea hygrometrica, a resurrection plant that inhabits drought and alkaline Karst areas, a genomic DNA library from B. hygrometrica was constructed and subsequently transformed into Arabidopsis using binary bacterial artificial chromosome (BIBAC) vectors. Transgenic lines were screened under osmotic and alkaline conditions, leading to the identification of Clone L1-4 that conferred osmotic and alkaline tolerance. Sequence analyses revealed that L1-4 contained a 49-kb retroelement fragment from B. hygrometrica, of which only a truncated sequence was present in L1-4 transgenic Arabidopsis plants. Additional subcloning revealed that activity resided in a 2-kb sequence, designated Osmotic and Alkaline Resistance 1 (OAR1). In addition, transgenic Arabidopsis lines carrying an OAR1-homologue also showed similar stress tolerance phenotypes. Physiological and molecular analyses demonstrated that OAR1-transgenic plants exhibited improved photochemical efficiency and membrane integrity and biomarker gene expression under both osmotic and alkaline stresses. Short transcripts that originated from OAR1 were increased under stress conditions in both B. hygrometrica and Arabidopsis carrying OAR1. The relative copy number of OAR1 was stable in transgenic Arabidopsis under stress but increased in B. hygrometrica. Taken together, our results indicated a potential role of OAR1 element in plant tolerance to osmotic and alkaline stresses, and verified the feasibility of the BIBAC transformation technique to identify functional genomic elements from physiological model species. PMID:24851859

Electronic Excitations of Alkali-Alkaline Earth Diatomic Molecules - Results from AB Initio Calculations

NASA Astrophysics Data System (ADS)

Pototschnig, Johann V.; Krois, Günter; Lackner, Florian; Ernst, Wolfgang E.

2014-06-01

Recently interest in polar diatomic molecules with a magnetic dipole moment has been growing. An example for such molecules is the combination of an alkali metal atom and an alkaline earth metal atom. These systems are quite small, containing only three valence electrons. Nevertheless calculations of excited states are challenging. Ab initio calculations for two sample systems, LiCa and RbSr, will be presented. The potential energy curves and transition dipole moments for the ground state and several excited states were determined, up to 25000 wn for LiCa and up to 22000 wn for RbSr. Multireference configuration interaction calculations (MRCI) based on complete active space self-consistent field wave functions (CASSCF) were used to determine the properties of the system as implemented in the MOLPRO software package. Effective core potentials (ECPs) and core polarization potentials (CCPs) were applied to reduce the computational effort, while retaining accuracy. The similarities and differences of the two systems will be discussed. In both systems the accurate description of the asymptotic values of the PECs corresponding to atomic D-states proved to be difficult. The results will be compared to recent experiments, showing that a combination of theory and experiment gives a reliable description of the systems. G. Krois, J.V. Pototschnig, F. Lackner and W.E. Ernst, J. Phys. Chem. A, 117, 13719-13731 (2013) H.-J. Werner and P. J. Knowles and G. Knizia and F. R. Manby and M. {Schütz} et al., MOLPRO, version 2010.1, see http://www.molpro.net/

Technical Information Resource on Rare Earth Elements Now Available to Public and Private Sector Stakeholders

EPA Science Inventory

A new EPA technical information resource, “Rare Earth Elements: A Review of Production, Processing, Recycling, and Associated Environmental Issues” has been produced as an introductory resource for those interested in learning more about REE mining and alternatives to meet demand...

Rare Earth Element Concentrations in Geothermal Wells at the Puna Geothermal Field, Hawaii

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

Fowler, Andrew; Zierenberg, Robert

Rare earth element concentrations in the geothermal wells at the Puna geothermal field, Hawaii. Samples taken from geothermal wells KS-5, KS-6W, KS-9W, KS-14E, and KS-16N. Includes pH and concentrations for Cerium, Dysprosium, Erbium, Europium, Gadolinium, Holmium, Lanthanum, Lutetium, Neodymium, Praseodymium, Samarium, Terbium, Thulium, Yttrium, and Ytterbium. Samples collected on November 11-17, 2016.

Rationally designed mineralization for selective recovery of the rare earth elements

PubMed Central

Hatanaka, Takaaki; Matsugami, Akimasa; Nonaka, Takamasa; Takagi, Hideki; Hayashi, Fumiaki; Tani, Takao; Ishida, Nobuhiro

2017-01-01

The increasing demand for rare earth (RE) elements in advanced materials for permanent magnets, rechargeable batteries, catalysts and lamp phosphors necessitates environmentally friendly approaches for their recovery and separation. Here, we propose a mineralization concept for direct extraction of RE ions with Lamp (lanthanide ion mineralization peptide). In aqueous solution containing various metal ions, Lamp promotes the generation of RE hydroxide species with which it binds to form hydrophobic complexes that accumulate spontaneously as insoluble precipitates, even under physiological conditions (pH ∼6.0). This concept for stabilization of an insoluble lanthanide hydroxide complex with an artificial peptide also works in combination with stable scaffolds like synthetic macromolecules and proteins. Our strategy opens the possibility for selective separation of target metal elements from seawater and industrial wastewater under mild conditions without additional energy input. PMID:28548098

Rare earth element abundances in rocks and minerals from the Fiskenaesset Complex, West Greenland. [comparison with lunar anorthosites

NASA Technical Reports Server (NTRS)

Henderson, P.; Fishlock, S. J.; Laul, J. C.; Cooper, T. D.; Conard, R. L.; Boynton, W. V.; Schmitt, R. A.

1976-01-01

The paper reports activation-analysis determinations of rare-earth-element (REE) and other trace-element concentrations in selected rocks, plagioclase, and mafic separates from the Fiskenaesset Complex. The REE abundances are found to be very low and atypical in comparison with other terrestrial anorthosites. The plagioclases are shown to be characterized by a deficiency in heavy RE elements relative to light ones and a positive Eu anomaly, while the mafic separates are enriched in heavy rare earths and have no Eu anomaly, except in one sample. It is found that the bulk and trace-element abundances of the plagioclases are similar to those observed in some lunar anorthosites, but the degree of Eu anomaly is less in the plagioclases. The data are taken as confirmation of the idea that fractionation processes were involved in the origin of the Complex, and it is concluded that the Complex may have been produced from a magma generated by partial melting of a garnet-bearing source.

Rare earth elements minimal harvest year variation facilitates robust geographical origin discrimination: The case of PDO "Fava Santorinis".

PubMed

Drivelos, Spiros A; Danezis, Georgios P; Haroutounian, Serkos A; Georgiou, Constantinos A

2016-12-15

This study examines the trace and rare earth elemental (REE) fingerprint variations of PDO (Protected Designation of Origin) "Fava Santorinis" over three consecutive harvesting years (2011-2013). Classification of samples in harvesting years was studied by performing discriminant analysis (DA), k nearest neighbours (κ-NN), partial least squares (PLS) analysis and probabilistic neural networks (PNN) using rare earth elements and trace metals determined using ICP-MS. DA performed better than κ-NN, producing 100% discrimination using trace elements and 79% using REEs. PLS was found to be superior to PNN, achieving 99% and 90% classification for trace and REEs, respectively, while PNN achieved 96% and 71% classification for trace and REEs, respectively. The information obtained using REEs did not enhance classification, indicating that REEs vary minimally per harvesting year, providing robust geographical origin discrimination. The results show that seasonal patterns can occur in the elemental composition of "Fava Santorinis", probably reflecting seasonality of climate. Copyright © 2016 Elsevier Ltd. All rights reserved.

Geochemistry of rare earth elements in Permian coals from the Huaibei Coalfield, China

USGS Publications Warehouse

Zheng, Lingyun; Liu, Gaisheng; Chou, C.-L.; Qi, C.; Zhang, Y.

2007-01-01

The rare earth elements (REEs) in coals are important because of: (a) REE patterns can be an indicator of the nature of source rocks of the mineral matter as well as sedimentary environments; (b) REEs abundance in coal may have industrial-significance. In this study, a total of thirty-four samples of Permian coal, partings, roof, and floor were collected from the Huaibei Coalfield, Anhui Province, China. Abundances of rare earth elements (REEs) and other elements in the samples were determined by inductively coupled-plasma mass spectrometry (ICP-MS) and inductively coupled-plasma atomic emission spectrometry (ICP-AES). The results show that the REEs are enriched in coals in the Huaibei Coalfield as compared with Chinese and U.S. coals and the world coal average. Coals in the Lower Shihezi Formation (No. 7, 5, and 4 Coals) and Upper Shihezi Formation (No. 3) have higher REE abundances than the coals in Shanxi Formation (No. 10). Magmatic intrusion resulted in high enrichment of REEs concentrations in No. 5 and 7 Coals. The REE abundances are positively correlated with the ash content. The mineral matter in these coals is mainly made up of clay minerals and carbonates. The REEs are positively correlated with lithophile elements including Si, Al, Ti, Fe, and Na, which are mainly distributed in clay minerals, indicating that REEs are contained mainly in clay minerals. The REE abundances in coals normalized by the ash are higher than that in partings. REEs abundances of coals cannot be accounted for by the REE content in the mineral matter, and some REEs associated with organic matter in coals. ?? 2007 Elsevier Ltd. All rights reserved.

Carbon footprint assessment of recycling technologies for rare earth elements: A case study of recycling yttrium and europium from phosphor.

PubMed

Hu, Allen H; Kuo, Chien-Hung; Huang, Lance H; Su, Chao-Chin

2017-02-01

Rare earth elements are key raw materials in high-technology industries. Mining activities and manufacturing processes of such industries have caused considerable environmental impacts, such as soil erosion, vegetation destruction, and various forms of pollution. Sustaining the long-term supply of rare earth elements is difficult because of the global shortage of rare earth resources. The diminishing supply of rare earth elements has attracted considerable concern because many industrialized countries regarded such elements as important strategic resources for economic growth. This study aims to explore the carbon footprints of yttrium and europium recovery techniques from phosphor. Two extraction recovery methods, namely, acid extraction and solvent extraction, were selected for the analysis and comparison of carbon footprints. The two following functional units were used: (1) the same phosphor amounts for specific Y and Eu recovery concentrations, and (2) the same phosphor amounts for extraction. For acid extraction method, two acidic solutions (H 2 SO 4 and HCl) were used at two different temperatures (60 and 90°C). For solvent extraction method, acid leaching was performed followed by ionic liquid extraction. Carbon footprints from acid and solvent extraction methods were estimated to be 10.1 and 10.6kgCO 2 eq, respectively. Comparison of the carbon emissions of the two extraction methods shows that the solvent extraction method has significantly higher extraction efficiency, even though acid extraction method has a lower carbon footprint. These results may be used to develop strategies for life cycle management of rare earth resources to realize sustainable usage. Copyright © 2016 Elsevier Ltd. All rights reserved.

Active earth pressure model tests versus finite element analysis

NASA Astrophysics Data System (ADS)

Pietrzak, Magdalena

2017-06-01

The purpose of the paper is to compare failure mechanisms observed in small scale model tests on granular sample in active state, and simulated by finite element method (FEM) using Plaxis 2D software. Small scale model tests were performed on rectangular granular sample retained by a rigid wall. Deformation of the sample resulted from simple wall translation in the direction `from the soil" (active earth pressure state. Simple Coulomb-Mohr model for soil can be helpful in interpreting experimental findings in case of granular materials. It was found that the general alignment of strain localization pattern (failure mechanism) may belong to macro scale features and be dominated by a test boundary conditions rather than the nature of the granular sample.

Alkaline earth lead and tin compounds Ae2Pb, Ae2Sn, Ae = Ca, Sr, Ba, as thermoelectric materials

PubMed Central

Parker, David; Singh, David J

2013-01-01

We present a detailed theoretical study of three alkaline earth compounds Ca2Pb, Sr2Pb and Ba2Pb, which have undergone little previous study, calculating electronic band structures and Boltzmann transport and bulk moduli using density functional theory. We also study the corresponding tin compounds Ca2Sn, Sr2Sn and Ba2Sn. We find that these are all narrow band gap semiconductors with an electronic structure favorable for thermoelectric performance, with substantial thermopowers for the lead compounds at temperature ranges from 300 to 800 K. For the lead compounds, we further find very low calculated bulk moduli—roughly half of the values for the lead chalcogenides, suggestive of soft phonons and hence low lattice thermal conductivity. All these facts indicate that these materials merit experimental investigation as potential high performance thermoelectrics. We find good potential for thermoelectric performance in the environmentally friendly stannide materials, particularly at high temperature. PMID:27877610

Methanol synthesis using a catalyst combination of alkali or alkaline earth salts and reduced copper chromite for methanol synthesis

DOEpatents

Tierney, John W.; Wender, Irving; Palekar, Vishwesh M.

1993-01-01

The present invention relates to a novel route for the synthesis of methanol, and more specifically to the production of methanol by contacting synthesis gas under relatively mild conditions in a slurry phase with a catalyst combination comprising reduced copper chromite and basic alkali salts or alkaline earth salts. The present invention allows the synthesis of methanol to occur in the temperature range of approximately 100.degree.-160.degree. C. and the pressure range of 40-65 atm. The process produces methanol with up to 90% syngas conversion per pass and up to 95% methanol selectivity. The only major by-product is a small amount of easily separated methyl formate. Very small amounts of water, carbon dioxide and dimethyl ether are also produced. The present catalyst combination also is capable of tolerating fluctuations in the H.sub.2 /CO ratio without major deleterious effect on the reaction rate. Furthermore, carbon dioxide and water are also tolerated without substantial catalyst deactivation.

A survey of 16 rare Earth elements in the major foods in China.

PubMed

Jiang, Ding Guo; Yang, Jie; Zhang, Shuo; Yang, Da Jin

2012-06-01

The aim of this survey was to investigate the level of contamination of the most consumed foods in China with 16 rare earth elements (REEs), and to provide the basic data for establishing and revising food safety standards for REEs. Sixteen REEs in foods were measured by inductively coupled plasma-mass spectrometry (ICP-MS) in the labs of the Centers for Disease Control and Prevention of four provinces and two municipalities, during 2009-2010. 1 231 samples were analyzed and 19 121 concentration data of 16 REEs were collected. The REEs levels in the investigated foods varied significantly. The concentrations of cerium (Ce), dysprosium (Dy), yttrium (Y), lanthanum (La), and neodymium (Nd) were relatively high, while the remaining eleven REEs were at low levels. The mean values of total rare earth element oxides (REOs) in cereals, fresh vegetables, fresh aquatic products, fresh meats and eggs varied from 0.052 mg/kg to 0.337 mg/kg. 16 REEs in the major foods were at very low contamination levels in the investigated regions. Copyright © 2012 The Editorial Board of Biomedical and Environmental Sciences. Published by Elsevier B.V. All rights reserved.

Cation exchange properties of zeolites in hyper alkaline aqueous media.

PubMed

Van Tendeloo, Leen; de Blochouse, Benny; Dom, Dirk; Vancluysen, Jacqueline; Snellings, Ruben; Martens, Johan A; Kirschhock, Christine E A; Maes, André; Breynaert, Eric

2015-02-03

Construction of multibarrier concrete based waste disposal sites and management of alkaline mine drainage water requires cation exchangers combining excellent sorption properties with a high stability and predictable performance in hyper alkaline media. Though highly selective organic cation exchange resins have been developed for most pollutants, they can serve as a growth medium for bacterial proliferation, impairing their long-term stability and introducing unpredictable parameters into the evolution of the system. Zeolites represent a family of inorganic cation exchangers, which naturally occur in hyper alkaline conditions and cannot serve as an electron donor or carbon source for microbial proliferation. Despite their successful application as industrial cation exchangers under near neutral conditions, their performance in hyper alkaline, saline water remains highly undocumented. Using Cs(+) as a benchmark element, this study aims to assess the long-term cation exchange performance of zeolites in concrete derived aqueous solutions. Comparison of their exchange properties in alkaline media with data obtained in near neutral solutions demonstrated that the cation exchange selectivity remains unaffected by the increased hydroxyl concentration; the cation exchange capacity did however show an unexpected increase in hyper alkaline media.

Behaviour of elements in soils developed from nephelinites at Mount Etinde (Cameroon): Impact of hydrothermal versus weathering processes

NASA Astrophysics Data System (ADS)

Etame, J.; Gerard, M.; Bilong, P.; Suh, C. E.

2009-05-01

The progressive weathering of 0.65 Ma nephelinites from Mount Etinde (South Western Cameroon) in a humid tropical setting has resulted in the formation of a 150 cm thick weathering crust. The soil profiles consist of three horizons: Ah/Bw/C. A major differentiation of the chemical and mineralogical parameters is related to the complexity of the saprolites, some of which were hydrothermally altered. Bulk geochemical and microgeochemical analyses were performed on selected minerals from the different horizons of two reference profiles, of which one (E 4) was developed from unaltered nephelinite (nephelinite U) while the other (BO 1) formed from hydrothermally altered nephelinite (nephelinite H). The results show that the primary minerals (clinopyroxene, nepheline, leucite, haüyne, titanomagnetite, perovskite, apatite and sphene) experienced differential weathering rates with primary minerals rich in rare earth elements (titanomagnetite, perovskite, apatite and sphene) surviving in the saprolite and the Bw horizons. The weathering of the primary minerals is reflected in the leaching of alkaline and alkaline-earth elements, except for Ba and Rb in the hydrothermalised nephelinite soil. The order of mobility is influenced by hydrothermal processes: Na > K > Rb > Ca > Cs > Sr in nephelinite U soil , Na > K > Sr > Ca > Mg in nephelinite H soil; Rb/Sr and Sr/Mg can be used as indicators of the kinetic of the weathering on nephelinite U and on nephelinite H. Barium enrichment is related to variable concentrations in the nephelinites, to the formation of crandallites and the leaching of surface horizons. The content of metallic elements is higher in nephelinite H soil than in the nephelinite U soil. Results show that hydrothermal alteration leads to an enrichment of light (La, Ce, Nd) and intermediate (Sm, Eu, Dy) rare earth elements. The enrichment in Cr and Pb in the surface horizons is discussed in relation to organic matter activity, the dissolution of magnetites, and

Rare earth element and uranium-thorium variations in tufa deposits from the Mono Basin, CA

NASA Astrophysics Data System (ADS)

Wilcox, E. S.; Tomascak, P. B.; Hemming, N.; Hemming, S. R.; Rasbury, T.; Stine, S.; Zimmerman, S. R.

2009-12-01

Samples of fossil tufa deposits from several localities in the Mono Basin, eastern California, were analyzed for trace element concentrations in order to better understand changes in lake composition in the past. These deposits were formed during the last glacial cycle, mostly during deglaciation (Benson et al., 1990, PPP). Three elevations are represented by the analyses. Samples from near Highway 167 were sampled between 2063 and 2069 m asl. Samples from near Thompson Road were sampled between 2015 and 2021 m. One layered mound was sampled at 1955 m. Concentrations of the lanthanide rare earth elements (REE), in particular the heavy/light (HREE/LREE) distributions, have been shown to be sensitive to alkalinity in modern saline lakes (e.g., Johannesson et al., 1994, GRL, 21, 773-776), and the same has been suggested for U/Th (Anderson et al., 1982, Science, 216, 514-516). Holocene to near-modern tufa towers exist in shallow water and around the current shoreline (1945 m). Tufa towers above 2000 m include a characteristic morphology termed thinolite, interpreted to represent pseudomorphs after the very cold water mineral ikaite. Most lower elevation towers do not have the thinolite morphology, but some layered tufa mounds at low elevations include several layers of thinolite, such as the one sampled for this project. Analyses were made on millimeter-scale bulk samples from tufa towers. Measurements were made on sample solutions with a Varian 820MS quadrupole ICP-MS. Mono Basin tufa samples have total REE concentrations ranging from 0.029 to 0.77 times average shales. Samples have flat to moderately HREE-enriched shale-normalized patterns with limited overall variability ([La/Lu]SN of 1.8 to 9.6) but with some variability in the slope of the HREE portion of the patterns. Tufa towers sampled from three elevations have (Gd/Lu)SN of 0.40 to 1.5. The REE patterns of most samples have small positive Ce anomalies, but a minority of samples, all from the layered tufa mound

Method of treating waste water

DOEpatents

Deininger, J. Paul; Chatfield, Linda K.

1991-01-01

A process of treating water to remove transuranic elements contained therein by adjusting the pH of a transuranic element-containing water source to within the range of about 6.5 to about 14.0, admixing the water source with an alkali or alkaline earth ferrate in an amount sufficient to form a precipitate within the water source, the amount of ferrate effective to reduce the transuranic element concentration in the water source, permitting the precipitate in the admixture to separate and thereby yield a supernatant liquid having a reduced transuranic element concentration, and separating the supernatant liquid having the reduced transuranic element concentration from the admixture is provided. Additionally, a water soluble salt, e.g., a zirconium salt, can be added with the alkali or alkaline earth ferrate in the process to provide greater removal efficiencies. A composition of matter including an alkali or alkaline earth ferrate and a water soluble salt, e.g., a zirconium salt, is also provided.

Structural, optical absorption and photoluminescence spectral studies of Sm3+ ions in Alkaline-Earth Boro Tellurite glasses

NASA Astrophysics Data System (ADS)

Siva Rama Krishna Reddy, K.; Swapna, K.; Mahamuda, Sk.; Venkateswarlu, M.; Srinivas Prasad, M. V. V. K.; Rao, A. S.; Prakash, G. Vijaya

2018-05-01

Sm3+ ions doped Alkaline-Earth Boro Tellurite (AEBT) glasses were prepared by using conventional melt quenching technique and characterized using the spectroscopic techniques such as FT-IR, optical absorption, emission and decay spectral measurements to understand their utility in optoelectronic devices. From absorption spectra, the bonding parameters, nephelauxetic ratios were determined to know the nature of bonding between Sm3+ ions and its surrounding ligands. From the measured oscillator strengths, the Judd-Ofelt (J-O) intensity parameters were evaluated and in turn used to estimate various radiative parameters for the fluorescent levels of Sm3+ ions in AEBT glasses. The PL spectra of Sm3+ ions exhibit three emission bands corresponding to the transitions 4G5/2 → 6H5/2, 6H7/2 and 6H9/2 in the visible region for which the emission cross-sections and branching ratios were evaluated. The decay spectral profiles measured for 4G5/2 → 6H7/2 transition showed single exponential for lower concentration and non-exponential for higher concentration of doped rare earth ion in the as prepared glasses. Conversion of decay spectral profiles from single to non-exponential have been analyzed using Inokuti-Hirayama (I-H) model to understand the energy transfer mechanism involved in the decay process. CIE Chromaticity coordinates were measured using emission spectral data to identify the exact region of emission from the as-prepared glasses. From the evaluated radiative parameters, emission cross-sections and quantum efficiencies, it was observed that AEBT glass with 1 mol% of Sm3+ ions is more suitable for designing optoelectronic devices.

The long-range non-additive three-body dispersion interactions for the rare gases, alkali, and alkaline-earth atoms

NASA Astrophysics Data System (ADS)

Tang, Li-Yan; Yan, Zong-Chao; Shi, Ting-Yun; Babb, James F.; Mitroy, J.

2012-03-01

The long-range non-additive three-body dispersion interaction coefficients Z111, Z112, Z113, and Z122 are computed for many atomic combinations using standard expressions. The atoms considered include hydrogen, the rare gases, the alkali atoms (up to Rb), and the alkaline-earth atoms (up to Sr). The term Z111 arising from three mutual dipole interactions is known as the Axilrod-Teller-Muto coefficient or the DDD (dipole-dipole-dipole) coefficient. Similarly, the terms Z112, Z113, and Z122 arise from the mutual combinations of dipole (1), quadrupole (2), and octupole (3) interactions between atoms and they are sometimes known, respectively, as dipole-dipole-quadrupole, dipole-dipole-octupole, and dipole-quadrupole-quadrupole coefficients. Results for the four Z coefficients are given for the homonuclear trimers, for the trimers involving two like-rare-gas atoms, and for the trimers with all combinations of the H, He, and Li atoms. An exhaustive compilation of all coefficients between all possible atomic combinations is presented as supplementary data.

High contents of rare earth elements (REEs) in stream waters of a Cu-Pb-Zn mining area.

PubMed

Protano, G; Riccobono, F

2002-01-01

Stream waters draining an old mining area present very high rare earth element (REE) contents, reaching 928 microg/l as the maximum total value (sigmaREE). The middle rare earth elements (MREEs) are usually enriched with respect to both the light (LREEs) and heavy (HREEs) elements of this group, producing a characteristic "roof-shaped" pattern of the shale Post-Archean Australian Shales-normalized concentrations. At the Fenice Capanne Mine (FCM), the most important base metal mine of the study area, the REE source coincides with the mine tailings, mostly the oldest ones composed of iron-rich materials. The geochemical history of the REEs released into Noni stream from wastes in the FCM area is strictly determined by the pH, which controls the REE speciation and in-stream processes. The formation of Al-rich and mainly Fe-rich flocs effectively scavenges the REEs, which are readily and drastically removed from the solution when the pH approaches neutrality. Leaching experiments performed on flocs and waste materials demonstrate that Fe-oxides/oxyhydroxides play a key role in the release of lanthanide elements into stream waters. The origin of the "roof-shaped" REE distribution pattern as well as the peculiar geochemical behavior of some lanthanide elements in the aqueous system are discussed.

Influences of alkaline earth metal substitution on the crystal structure and physical properties of magnetic RuSr1.9A0.1GdCu2O8 (A = Ca, Sr, and Ba) superconductors.

PubMed

Hur, Su Gil; Park, Dae Hoon; Hwang, Seong-Ju; Kim, Seung Joo; Lee, J H; Lee, Sang Young

2005-11-24

We have investigated the effect of alkaline earth metal substitution on the crystal structure and physical properties of magnetic superconductors RuSr(1.9)A(0.1)GdCu(2)O(8) (A = Ca, Sr, and Ba) in order to probe an interaction between the magnetic coupling of the RuO(2) layer and the superconductivity of the CuO(2) layer. X-ray diffraction and X-ray absorption spectroscopic analyses demonstrate that the isovalent substitution of Sr ions with Ca or Ba ions makes it possible to tune the interlayer distance between the CuO(2) and the RuO(2) layers. From the measurements of electrical resistance and magnetic susceptibility, it was found that, in contrast to negligible change of magnetization, both of the alkaline earth metal substitutions lead to a notable depression of zero-resistance temperature T(c) (DeltaT(c) approximately 17-19 K). On the basis of the absence of a systematic correlation between the T(c) and the interlayer distance/magnetization, we have concluded that the internal magnetic field of the RuO(2) layer has insignificant influence on the superconducting property of the CuO(2) layer in the ruthenocuprate.

Siderophile and chalcophile element abundances in oceanic basalts, Pb isotope evolution and growth of the earth's core

NASA Technical Reports Server (NTRS)

Newsom, H. E.; White, W. M.; Jochum, K. P.; Hofmann, A. W.

1986-01-01

The hypothesis that the mantle Pb isotope ratios reflect continued extraction of Pb into the earth's core over geologic time is evaluated by studying the depeletion of chalcophile and siderophile elements in the mantle. Oceanic basalt samples are analyzed in order to determine the Pb, Sr, and Nd isotropic compositions and the abundances of siderophile and chalcophile elements and incompatible lithophile elements. The data reveal that there is no systematic variation of siderophile or chalcophile element abundances relative to abundances of lithophile elements and the Pb/Ce ratio of the mantle is constant. It is suggested that the crust formation involves nonmagmatic and magmatic processes.

Hydrogen storage property of alkali and alkaline-earth metal atoms decorated C24 fullerene: A DFT study

NASA Astrophysics Data System (ADS)

Zhang, Yafei; Cheng, Xinlu

2018-04-01

The hydrogen storage behavior of alkali and alkaline-earth metal (AM = Li, Na, K, Mg, Ca) atoms decorated C24 fullerene was investigated by using density functional theory (DFT) study. Our results indicate that the AM atoms prefer to adsorb atop the center of tetragon of C24 fullerene with the largest binding energy than other possible adsorption sites. Moreover, the hydrogen storage gravimetric density of 24H2/6Li/C24, 24H2/6Na/C24 and 36H2/6Ca/C24 configurations reaches up to 12.7 wt%, 10.1 wt% and 12 wt%, higher than the year 2020 target from the US department of energy (DOE). Also, the average adsorption energies of H2 molecules of the 24H2/6Li/C24, 24H2/6Na/C24 and 36H2/6Ca/C24 configurations are -0.198 eV/H2, -0.164 eV/H2 and -0.138 eV/H2, locate the desirable range under the physical adsorption at near ambient conditions. These findings will have important implications on designing new hydrogen storage materials in the future.

Germanium and Rare Earth Element accumulation in woody bioenergy crops

NASA Astrophysics Data System (ADS)

Hentschel, Werner

2016-04-01

Germanium and REEs are strategic elements that are used for high tech devices and engineered systems, however these elements are hardly concentrated into mineable ore deposits. Since these elements occur widely dispersed in the earth crust with concentrations of several mgṡkg-1 (Ge 1.6 mgṡkg-1, Nd 25 mgṡkg-1) a new possibility to gain these elements could be phytomining, a technique that uses plants to extract elements from soils via their roots. Since knowledge about accumulating plant species is quite limited we conducted research on the concentrations of strategic elements in wood and leaves of fast growing tree species (Salix spec., Populus spec., Betula pendula, Alnus glutinosa, Fraxinus excelsior, Acer pseudoplatanus). In total 35 study sites were selected in the mining affected area around Freiberg (Saxony, Germany), differing in their species composition and degree of contamination with toxic trace metals (Pb, As, Cd). On each site plant tissues (wood and leaves, respectively) of different species were sampled. In addition soil samples were taken from a soil depth of 0 - 30 cm and 30 - 60 cm. The aim of our work was to investigate correlations between the concentrations of the target elements in plant tissues and soil characteristics like pH, texture, nutrients and concentrations in six operationally defined soil fractions (mobile, acid soluble, oxidizable, amorphic oxides, crystalline oxides, residual or siliceous). Concentrations of elements in soil extracts and plant tissues were measured with ICP-MS. The element Nd was selected as representative for the group of REEs, since this element showed a high correlation with the concentrations of the other REE We found that the concentration of Nd in the leaves (0.31 mgṡkg-1Nd) were several times higher than in herbaceous species (0.05 mgṡkg-1 Nd). The concentration of Ge in leaves were ten times lower than that of Nd whereas in herbaceous species Nd and Ge were in equal magnitude. Within the tree

METHOD OF MAKING ALLOYS OF SECOND RARE EARTH SERIES METALS

DOEpatents

Baker, R.D.; Hayward, B.R.

1963-01-01

>This invention relates to a process for alloying the second rare earth series metals with Mo, Nb, or Zr. A halide of the rare earth metal is mixed with about 1 to 20 at.% of an oxide of Mo, Nb, or Zr. Iodine and an alkali or alkaline earth metal are added, and the resulting mixture is heated in an inert atmosphere to 350 deg C. (AEC)

Geology and market-dependent significance of rare earth element resources

NASA Astrophysics Data System (ADS)

Simandl, G. J.

2014-12-01

China started to produce rare earth elements (REEs) in the 1980s, and since the mid-1990s, it has become the dominant producer. Rare earth element export quotas first introduced by the Chinese government in the early 2000s were severely reduced in 2010 and 2011. This led to strong government-created disparity between prices within China and the rest of the world. Industrialized countries identified several REEs as strategic metals. Because of rapid price increases of REE outside of China, we have witnessed a world-scale REE exploration rush. The REE resources are concentrated in carbonatite-related deposits, peralkaline igneous rocks, pegmatites, monazite ± apatite veins, ion adsorption clays, placers, and some deep ocean sediments. REE could also be derived as a by-product of phosphate fertilizer production, U processing, mining of Ti-Zr-bearing placers, and exploitation of Olympic Dam subtype iron oxide copper gold (IOCG) deposits. Currently, REEs are produced mostly from carbonatite-related deposits, but ion adsorption clay deposits are an important source of heavy REE (HREE). Small quantities of REE are derived from placer deposits and one peralkaline intrusion-related deposit. The ideal REE development targets would be located in a politically stable jurisdiction with a pro-mining disposition such as Canada and Australia. REE grade, HREE/light REE (LREE) ratio of the mineralization, tonnage, mineralogy, and permissive metallurgy are some of the key technical factors that could be used to screen potential development projects. As REEs are considered strategic metals from economic, national security, and environmental points of view, technical and economic parameters alone are unlikely to be used in REE project development decision-making. Recycling of REE is in its infancy and unless legislated, in the short term, it is not expected to contribute significantly to the supply of REE.

Bioleaching of rare earth elements from waste phosphors and cracking catalysts

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

Reed, David W.; Fujita, Yoshiko; Daubaras, Dayna L.

Four microbial cultures were evaluated for organic acid production and their potential utility for leaching of rare earth elements (REE) from retorted phosphor powder (RPP) and spent fluidized cracking catalyst (FCC). Three of the cultures (2 bacterial, 1 fungal) were isolated from environmental and industrial materials known to contain rare earth elements. The other was the well-known and industrially important bacterium Gluconobacter oxydans. Gluconic acid was the predominant identified organic acid produced by all of the cultures; citric and acetic acid were among the other acids detected. There was also maximum REE leaching by cell free culture supernatants obtained withmore » Gluconobacter and the FCC; 49% of total REE was recovered, with preferential recovery of lanthanum over cerium. The phosphor powder was more difficult to leach; only ~2 % total REE was leached from RPP with Gluconobacter. Tests with the RPP indicated that the extent of REE solubilization was similar whether whole cell cultures or cell-free supernatants were used. However, Gluconobacter cell-free culture supernatants with 10-15 mM gluconic acid outperformed abiotically prepared leaching solutions with 30 mM gluconic acid concentrations. Abiotic tests showed that increasing gluconic acid concentrations increased leaching efficiency; for example, total REE leaching from FCC increased from 24 to 36 to 45% when gluconic acid was increased from 10 to 30 to 90 mM. Our research shows that utilizing microorganisms that produce gluconic acid can result in effective leaching of REE from waste materials, and optimizing gluconic acid production will improve recovery.« less

Bioleaching of rare earth elements from waste phosphors and cracking catalysts

DOE PAGES

Reed, David W.; Fujita, Yoshiko; Daubaras, Dayna L.; ...

2016-08-22

Four microbial cultures were evaluated for organic acid production and their potential utility for leaching of rare earth elements (REE) from retorted phosphor powder (RPP) and spent fluidized cracking catalyst (FCC). Three of the cultures (2 bacterial, 1 fungal) were isolated from environmental and industrial materials known to contain rare earth elements. The other was the well-known and industrially important bacterium Gluconobacter oxydans. Gluconic acid was the predominant identified organic acid produced by all of the cultures; citric and acetic acid were among the other acids detected. There was also maximum REE leaching by cell free culture supernatants obtained withmore » Gluconobacter and the FCC; 49% of total REE was recovered, with preferential recovery of lanthanum over cerium. The phosphor powder was more difficult to leach; only ~2 % total REE was leached from RPP with Gluconobacter. Tests with the RPP indicated that the extent of REE solubilization was similar whether whole cell cultures or cell-free supernatants were used. However, Gluconobacter cell-free culture supernatants with 10-15 mM gluconic acid outperformed abiotically prepared leaching solutions with 30 mM gluconic acid concentrations. Abiotic tests showed that increasing gluconic acid concentrations increased leaching efficiency; for example, total REE leaching from FCC increased from 24 to 36 to 45% when gluconic acid was increased from 10 to 30 to 90 mM. Our research shows that utilizing microorganisms that produce gluconic acid can result in effective leaching of REE from waste materials, and optimizing gluconic acid production will improve recovery.« less

Partitioning of light lithophile elements during basalt eruptions on Earth and application to Martian shergottites

NASA Astrophysics Data System (ADS)

Edmonds, Marie

2015-02-01

An enigmatic record of light lithophile element (LLE) zoning in pyroxenes in basaltic shergottite meteorites, whereby LLE concentrations decrease dramatically from the cores to the rims, has been interpreted as being due to partitioning of LLE into a hydrous vapor during magma ascent to the surface on Mars. These trends are used as evidence that Martian basaltic melts are water-rich (McSween et al., 2001). Lithium and boron are light lithophile elements (LLE) that partition into volcanic minerals and into vapor from silicate melts, making them potential tracers of degassing processes during magma ascent to the surface of Earth and of other planets. While LLE degassing behavior is relatively well understood for silica-rich melts, where water and LLE concentrations are relatively high, very little data exists for LLE abundance, heterogeneity and degassing in basaltic melts. The lack of data hampers interpretation of the trends in the shergottite meteorites. Through a geochemical study of LLE, volatile and trace elements in olivine-hosted melt inclusions from Kilauea Volcano, Hawaii, it can be demonstrated that lithium behaves similarly to the light to middle rare Earth elements during melting, magma mixing and fractionation. Considerable heterogeneity in lithium and boron is inherited from mantle-derived primary melts, which is dominant over the fractionation and degassing signal. Lithium and boron are only very weakly volatile in basaltic melt erupted from Kilauea Volcano, with vapor-melt partition coefficients <0.1. Degassing of LLE is further inhibited at high temperatures. Pyroxene and associated melt inclusion LLE concentrations from a range of volcanoes are used to quantify lithium pyroxene-melt partition coefficients, which correlate negatively with melt H2O content, ranging from 0.13 at low water contents to <0.08 at H2O contents >4 wt%. The observed terrestrial LLE partitioning behavior is extrapolated to Martian primitive melts through modeling. The zoning

Rare earth elements in parasol mushroom Macrolepiota procera.

PubMed

Falandysz, Jerzy; Sapkota, Atindra; Mędyk, Małgorzata; Feng, Xinbin

2017-04-15

This study aimed to investigate occurrence and distribution of 16 rare earth elements (REEs) in edible saprobic mushroom Macrolepiota procera, and to estimate possible intake and risk to human consumer. Mushrooms samples were collected from sixteen geographically diverse sites in the northern regions of Poland. The results showed that for Ce as the most abundant among the RREs in edible caps, the mean concentration was at 0.18±0.29mgkg -1 dry biomass. The mean concentration for Σ16 REEs determined in caps of fungus was 0.50mgkg -1 dry biomass and in whole fruiting bodies was 0.75mgkg -1 dry biomass. From a point of view by consumer, the amounts of REEs contained in edible caps of M. procera could be considered small. Hence, eating a tasty caps of this fungus would not result in a health risk for consumer because of exposure to the REEs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Geochemistry of rare earth elements within waste rocks from the Montviel carbonatite deposit, Québec, Canada.

PubMed

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

2018-04-01

Several rare earth element (REE) mine projects around the world are currently at the feasibility stage. Unfortunately, few studies have evaluated the contamination potential of REE and their effects on the environment. In this project, the waste rocks from the carbonatites within the Montviel proterozoic alkaline intrusion (near Lebel-sur-Quévillon, Quebec, Canada) are assessed in this research. The mineralization is mainly constituted by light REE (LREE) fluorocarbonates (qaqarssukite-Ce, kukharenkoite-Ce), LREE carbonates (burbankite, Sr-Ba-Ca-REE, barytocalcite, strontianite, Ba-REE-carbonates), and phosphates (apatite, monazite). The gangue minerals are biotites, chlorite, albite, ankerite, siderite, and calcite. The SEM-EDS analyses show that (i) the majority of REE are associated with the fine fraction (< 106 μm), (ii) REE are mainly associated with carbonates, (iii) all analyzed minerals preferably contain LREE (La, Ce, Pr, Nd, Sm, Eu), (iv) the sum of LREE in each analyzed mineral varies between ~ 3 and 10 wt%, (v) the heavy REE (HREE) identified are Gd and Yb at < 0.4 wt%, and (vi) three groups of carbonate minerals were observed containing variable concentrations of Ca, Na, and F. Furthermore, the mineralogical composition of REE-bearing minerals, REE mobility, and REE speciation was investigated. The leachability and geochemical behavior of these REE-bearing mine wastes were tested using normalized kinetic testing (humidity cells). Leachate results displayed higher LREE concentrations, with decreasing shale-normalized patterns. Thermodynamical equilibrium calculations suggest that the precipitation of secondary REE minerals may control the REE mobility.

The chemistry of rare earth elements in the solar nebula

NASA Technical Reports Server (NTRS)

Larimer, J. W.; Bartholomay, H. A.; Fegley, B.

1984-01-01

The high concentration of rare earth elements (REE) in primitive CaS suggests that the REE along with the other normally lithophile elements form stable sulfides under the unusual conditions which existed during the formation of enstatite chrondites. In order to acquire a more quantitative framework in which to interpret these data, the behavior of the REE in systems with solar, or slightly fractionated solar, composition is being studied. These new data introduce modest changes in the behavior of some of the REE when compared to previous studies. For example, the largest differences are in the stabilities of the gaseous monoxides of Ce, Eu, Tb, Ho, and Tm, all of which now appear to be less stable than previously thought, and YbO(g) which is somewhat more stable. Much more significant are the changes in REE distribution in the gas phase in fractionated systems, especially those made more reducing by changing the C/O ratio from the solar value of 0.6 to about 1.0. In almost all cases, the exceptions being Eu, Tm and Yb whose elemental gaseous species dominate, the monosulfides become more abundant. Moreover, the solid oxides of Eu, Tm and Yb become less stable under more reducing conditions which, in effect, should reduce the condensation temperature of all REE in more reduced systems.

Chemistry and origin of minor and trace elements in vitrinite concentrates from a rank series from the eastern United States, England, and Australia

USGS Publications Warehouse

Lyons, P.C.; Palmer, C.A.; Bostick, N.H.; Fletcher, J.D.; Dulong, F.T.; Brown, F.W.; Brown, Z.A.; Krasnow, M.R.; Romankiw, L.A.

1989-01-01

A rank series consisting of twelve vitrinite concentrates and companion whole-coal samples from mined coal beds in the eastern United States, England, and Australia were analyzed for C, H, N, O, ash, and 47 trace and minor elements by standard elemental, instrumental neutron activation analysis (INAA), and direct-current-arc spectrographic (DCAS) techniques. The reflectance of vitrinite, atomic H:C and O:C, and ash-free carbon data were used to determine ranks that range from high-volatile C bituminous coal to meta-anthracite. A van Krevelen (atomic H:C vs. O:C) diagram of the vitrinite concentrates shows a smooth curve having its lowest point at H:C = 0.18 and O:C = 0.01. This improves the van Krevelen diagram by the addition of our vitrinite concentrate from meta-anthracite from the Narragansett basin of New England. Boron content (400-450 ppm) in two Illinois basin vitrinite concentrates was about an order of magnitude higher than B contents in other concentrates analyzed. We attribute this to marine origin or hydrothermal activity. The alkaline-earth elements Ca, Mg and Ba (DCAS) have higher concentrations in our vitrinite concentrates from bituminous coals of the Appalachian basin, than they do in vitrinite concentrates from the marine-roofed bituminous coals of the Illinois basin; therefore, a nonmarine origin for these alkaline-earth elements is postulated for the Appalachian basin coals. An ion-exchange mechanism due to high concentrations of these elements as ions in diagenetic water, but probably not recent ground water, may be responsible for the relatively high values of these elements in Appalachian concentrates. Higher concentrations of Ni and Cr in one of the English vitrinite concentrates and of Zr in the Australian concentrate probably indicate organic association and detrital influence, respectively. ?? 1989.

Origin of Volatiles in Earth: Indigenous Versus Exogenous Sources Based on Highly Siderophile, Volatile Siderophile, and Light Volatile Elements

NASA Technical Reports Server (NTRS)

Righter, K.; Danielson, L.; Pando, K. M.; Marin, N.; Nickodem, K.

2015-01-01

Origin of Earth's volatiles has traditionally been ascribed to late accretion of material after major differentiation events - chondrites, comets, ice or other exogenous sources. A competing theory is that the Earth accreted its volatiles as it was built, thus water and other building blocks were present early and during differentiation and core formation (indigenous). Here we discuss geochemical evidence from three groups of elements that suggests Earth's volatiles were acquired during accretion and did not require additional sources after differentiation.

Hydrogen and syngas production by catalytic gasification of algal biomass (Cladophora glomerata L.) using alkali and alkaline-earth metals compounds.

PubMed

Ebadi, Abdol Ghaffar; Hisoriev, Hikmat; Zarnegar, Mohammad; Ahmadi, Hamed

2018-01-02

The steam gasification of algal biomass (Cladophora glomerata L.) in presence of alkali and alkaline-earth metal compounds catalysts was studied to enhance the yield of syngas and reduce its tar content through cracking and reforming of condensable fractions. The commercial catalysts used include NaOH, KHCO 3 , Na 3 PO 4 and MgO. The gasification runs carried out with a research scale, biomass gasification unit, show that the NaOH has a strong potential for production of hydrogen, along with the added advantages of char converting and tar destruction, allowing enhancement of produced syngas caloric value. When the temperature increased from 700°C to 900°C, the tar content in the gas sharply decreased, while the hydrogen yield increased. Increasing steam/biomass ratio significantly increased hydrogen yield and tar destruction; however, the particle size in the range of 0.5-2.5 mm played a minor role in the process.

Fractionation of rare-earth elements in allanite and monazite as related to geology of the Mt. Wheeler mine area, Nevada

USGS Publications Warehouse

Lee, D.E.; Bastron, H.

1967-01-01

Rare-earth contents of 20 allanites and 13 monazites, accessory minerals from a restricted outcrop area of intrusive granitic rocks, are reported. A quantity called sigma (??), which is the sum of the atomic percentages of La, Ce and Pr, is used as an index of composition with respect to the rare-earth elements. Values of sigma vary from 61.3 to 80.9 at.% for these allanites and monazites, representing an appreciable range of composition in terms of the rare-earth elements. Degree of fractionation of rare earths varies directly with CaO content of the granitic rocks, which in turn depends largely on proximity of limestone. Four xenoliths included in the study suggest that spotty mosaic equilibria are superimposed on the regional gradients and that locally the degree of fractionation of rare earths responds to whole rock composition over distances of a few yards or less. The chemistry of the granitic rocks under study appears to be similar in some respects to that of alkalio rocks and carbonatites. Allanites from the most calcium-rich rocks show a pronounced concentration of the most basic rare earths, and whole-rock concentrations of such rare constituents as total cerium earths, Zr, F, Ti, Ba and Sr increase sympathetically with whole-rock calcium. The explanation for the concentration gradients observed in this chemical system must involve assimilation more than magmatic differentiation. ?? 1967.

A set of alkali and alkaline-earth coordination polymers based on the ligand 2-(1H-benzotriazol-1-yl) acetic acid: Effects the radius of metal ions on structures and properties

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

Wang, Jin-Hua; Tang, Gui-Mei, E-mail: meiguit@163.com; Qin, Ting-Xiao

2014-11-15

Four new metal coordination complexes, namely, [Na(BTA)]{sub n} (1), [K{sub 2}(BTA){sub 2}(μ{sub 2}-H{sub 2}O)]{sub n} (2), and [M(BTA){sub 2}(H{sub 2}O){sub 2}]{sub n} (M=Ca(II) and Sr(II) for 3 and 4, respectively) [BTA=2-(1H-benzotriazol-1-yl) acetic anion], have been obtained under hydrothermal condition, by reacting the different alkali and alkaline-earth metal hydroxides with HBTA. Complexes 1–4 were structurally characterized by X-ray single-crystal diffraction, EA, IR, PXRD, and thermogravimetry analysis (TGA). These complexes display low-dimensional features displaying various two-dimensional (2D) and one-dimensional (1D) coordination motifs. Complex 1 displays a 2D layer with the thickness of 1.5 nm and possesses a topologic structure of a 11more » nodal net with Schläfli symbol of (3{sup 18}). Complex 2 also shows a thick 2D sheet and its topologic structure is a 9 nodes with Schläfli symbol of (3{sup 11}×4{sup 2}). Complexes 3 and 4 possess a 1D linear chain and further stack via hydrogen bonding interactions to generate a three-dimensional supramolecular architecture. These results suggest that both the coordination preferences of the metal ions and the versatile nature of this flexible ligand play a critical role in the final structures. The luminescent spectra show strong emission intensities in complexes 1–4, which display violet photoluminescence. Additionally, ferroelectric, dielectric and nonlinear optic (NLO) second-harmonic generation (SHG) properties of 2 are discussed in detail. - Graphical abstract: A set of alkali and alkaline-earth metal coordination polymers were hydrothermally synthesized by 2-(1H-benzotriazol-1-yl)acetic acid, displaying interesting topologic motifs from two-dimension to one-dimension and specific physical properties. - Highlights: • Alkali and alkaline-earth metal coordination polymers have been obtained. • The ligand 2-(1H-benzotriazol-1-yl)acetic acid has been adopted. • The two-dimensional and one

A volatile rich Earth's core?

NASA Astrophysics Data System (ADS)

Morard, G.; Antonangeli, D.; Andrault, D.; Nakajima, Y.

2017-12-01

The composition of the Earth's core is still an open question. Although mostly composed of iron, it contains impurities that lower its density and melting point with respect to pure Fe. Knowledge of the nature and abundance of light elements (O, S, Si, C or H) in the core has major implications for establishing the bulk composition of the Earth and for building the model of Earth's differentiation. Geochemical models of the Earth's formation point out that its building blocks were depleted in volatile elements compared to the chondritic abundance, therefore light elements such as S, H or C cannot be the major elements alloyed with iron in the Earth's core. However, such models should be compatible with the comparison of seismic properties of the Earth's core and physical properties of iron alloys under extreme conditions, such as sound velocity or density of solid and liquid. The present work will discuss the recent progress for compositional model issued from studies of phase diagrams and elastic properties of iron alloys under core conditions and highlight the compatibility of volatile elements with observed properties of the Earth's core, in potential contradiction with models derived from metal-silicate partitioning experiments.

OIB signatures in basin-related lithosphere-derived alkaline basalts from the Batain basin (Oman) - Constraints from 40Ar/39Ar ages and Nd-Sr-Pb-Hf isotopes

NASA Astrophysics Data System (ADS)

Witte, M.; Jung, S.; Pfänder, J. A.; Romer, R. L.; Mayer, B.; Garbe-Schönberg, D.

2017-08-01

Tertiary rift-related intraplate basanites from the Batain basin of northeastern Oman have low SiO2 (< 45.6 wt.%), high MgO (> 9.73 wt.%) and moderate to high Cr and Ni contents (Cr > 261 ppm, Ni > 181 ppm), representing near primary magmas that have undergone fractionation of mainly olivine and magnetite. Rare earth element systematics and p-T estimates suggest that the alkaline rocks are generated by different degrees of partial melting (4-13%) of a spinel-peridotite lithospheric mantle containing residual amphibole. The alkaline rocks show restricted variations of 87Sr/86Sr and 143Nd/144Nd ranging from 0.70340 to 0.70405 and 0.51275 to 0.51284, respectively. Variations in Pb isotopes (206Pb/204Pb: 18.59-18.82, 207Pb/204Pb: 15.54-15.56, 208Pb/204Pb: 38.65-38.98) of the alkaline rocks fall in the range of most OIB. Trace element constraints together with Sr-Nd-Pb isotope composition indicate that assimilation through crustal material did not affect the lavas. Instead, trace element variations can be explained by melting of a lithospheric mantle source that was metasomatized by an OIB-type magma that was accumulated at the base of the lithosphere sometimes in the past. Although only an area of less than 1000 km2 was sampled, magmatic activity lasted for about 5.5 Ma with a virtually continuous activity from 40.7 ± 0.7 to 35.3 ± 0.6 Ma. During this period magma composition was nearly constant, i.e. the degree of melting and the nature of the tapped source did not change significantly over time.

Transition from alkaline to calc-alkaline volcanism during evolution of the Paleoproterozoic Francevillian basin of eastern Gabon (Western Central Africa)

NASA Astrophysics Data System (ADS)

Thiéblemont, Denis; Bouton, Pascal; Préat, Alain; Goujou, Jean-Christian; Tegyey, Monique; Weber, Francis; Ebang Obiang, Michel; Joron, Jean Louis; Treuil, Michel

2014-11-01

We report new geochemical data for the volcanic and subvolcanic rocks associated with the evolution of the Francevillian basin of eastern Gabon during Paleoproterozoic times (c. 2.1-2 Ga). Filling of this basin has proceeded through four main sedimentary or volcano-sedimentary episodes, namely FA, FB, FC and FD. Volcanism started during the FB episode being present only in the northern part of the basin (Okondja sub-basin). This volcanism is ultramafic to trachytic in composition and displays a rather constant alkaline geochemical signature. This signature is typical of a within-plate environment, consistent with the rift-setting generally postulated for the Francevillian basin during the FB period. Following FB, the FC unit is 10-20 m-thick silicic horizon (jasper) attesting for a massive input of silica in the basin. Following FC, the FD unit is a c. 200-400 m-thick volcano-sedimentary sequence including felsic tuffs and epiclastic rocks. The geochemical signatures of these rocks are totally distinct from those of the FB alkaline lavas. High Th/Ta and La/Ta ratios attest for a calc-alkaline signature and slight fractionation between heavy rare-earth suggests melting at a rather low pressure. Such characteristics are comparable to those of felsic lavas associated with the Taupo zone of New Zealand, a modern ensialic back-arc basin. Following FD, the FE detrital unit is defined only in the Okondja region, probably associated with a late-stage collapse of the northern part of the basin. It is suggested that the alkaline to calc-alkaline volcanic transition reflects the evolution of the Francevillian basin from a diverging to a converging setting, in response to the onset of converging movements in the Eburnean Belt of Central Africa.

Earth Observatory Satellite system definition study. Report no. 5: System design and specifications. Part 1: Observatory system element specifications

NASA Technical Reports Server (NTRS)

1974-01-01

The performance, design, and quality assurance requirements for the Earth Observatory Satellite (EOS) Observatory and Ground System program elements required to perform the Land Resources Management (LRM) A-type mission are presented. The requirements for the Observatory element with the exception of the instruments specifications are contained in the first part.

Targeting heavy rare earth elements in carbonatite complexes

NASA Astrophysics Data System (ADS)

Broom-Fendley, S.; Wall, F.; Gunn, A. G.; Dowman, E.

2012-04-01

The world's main sources of the rare earth elements (REE) are concentrated in carbonatite complexes. These have the advantages of high grade and tonnage, combined with low thorium contents, yet they are generally enriched in light rare earths (LREE). The heavy rare earths (HREE, which include Eu-Lu and Y) are more highly sought after because of their role in new and green technologies. HREE are predominantly extracted from ion-adsorption clays in China. These are small, low grade deposits, which are often illegally mined by artisans. Increased government control, environmental legislation and local demand for REE in China have led to high prices and global concerns about the security of supply of the HREE. Alternative sources of the HREE are poorly documented. We present a review of such targets, including: (1) 'abnormal' carbonatites; (2) areas around LREE-rich complexes such as breccia, fenite and latter stage veins; and (3) weathered carbonatites. At Lofdal, Namibia, carbonatite dykes contain xenotime-(Y) together with LREE minerals. The original chemistry of the carbonatite magma, coupled with late-stage magma and fluid evolution, seem to be controlling factors [1, 2]. The Khibina carbonatite, Kola Peninsula, Russia, is an example of where early LREE carbonatites become increasing HREE-enriched as magmas evolve to carbo-hydrothermal fluids [3]. Around carbonatite complexes in Malawi HREE enrichment can be found in breccia and in fenite. Breccia around Songwe shows areas with high Y/La ratios within the matrix caused by narrow zones of xenotime enrichment. Fenite around Kangankunde and Chilwa Island has higher HREE:LREE ratios than the carbonatite [4]. At weathered complexes, such as at Mount Weld in Western Australia, changes in both HREE concentration and LREE:HREE ratios are observed. In currently unworked sections of the deposit, the HREE mineral churchite (YPO4.H2O) has formed concentrations due to groundwater flow [5]. These areas of enrichment are

Alkaline regenerative fuel cell energy storage system for manned orbital satellites

NASA Technical Reports Server (NTRS)

Martin, R. E.; Gitlow, B.; Sheibley, D. W.

1982-01-01

It is pointed out that the alkaline regenerative fuel cell system represents a highly efficient, lightweight, reliable approach for providing energy storage in an orbiting satellite. In addition to its energy storage function, the system can supply hydrogen and oxygen for attitude control of the satellite and for life support. A summary is presented of the results to date obtained in connection with the NASA-sponsored fuel cell technology advancement program, giving particular attention to the requirements of the alkaline regenerative fuel cell and the low-earth mission. Attention is given to system design guidelines, weight considerations, gold-platinum cathode cell performance, matrix development, the electrolyte reservoir plate, and the cyclical load profile tests.

Aegirine as a late-stage phase in an alkaline pluton associated with carbonate assimilation

NASA Astrophysics Data System (ADS)

Barnes, C. G.; Prestvik, T.; Hiller, J.

2006-12-01

The Hortavaer Complex in north-central Norway is a well-documented example of formation of an alkaline magmatic suite due to assimilation of carbonate and calc-silicate rocks (Vogt 1916; Gustavson & Prestvik, 1979; Barnes et al., 2003, 2005). The alkaline nature developed primarily as the result of increased stability and fractionation of Ca-pyroxene at the expense of olivine, resulting in enrichment of Na and K compared to Si. Calcic pyroxene is a common mineral in rocks that range from gabbro through diorite and monzonite to syenite, with a compositional range from augite to hedenbergite. In addition to calcic pyroxene, glassy, pale green aegirine occurs in veins near skarn-like assemblages in a zone where dioritic sheets were emplaced into syenite. Other vein minerals are biotite, albite, K-feldspar, calcite, and ilmenite. The aegirine is almost pure NaFeSi2O6 (Ae = 91.1%, Jd = 7.4%, Q = 1.5%; where Ae is the aegirine component, Jd the jadeite component, and Q the "quadrilateral" pyroxene component). Laser-ablation ICP-MS analysis shows that the aegirine crystals are typically lower in trace element concentrations than the calcic cpx. For example, Sr is < 2 ppm in the aegirine but > 20 ppm in cpx from evolved syenites and > 85 ppm in cpx from dioritic samples. Chondrite-normalized rare earth element (REE) patterns show a prominent cup shape and light REE abundances range from ~0.1X > 10X chondrites. Aegirine occurs in many locations in Norway (Neumann 1985), where it is generally related to alkaline rocks. Compared to the Hortavaer locality, aegirine from the type area in the Permian Oslo Region has 77% of the NaFeSi2O6 (Ae) component, whereas acmite has 89% Ae. Larsen and Raade (1997) presented c. 30 XRF and EMP analyses of pyroxenes from syenite pegmatites of the southern part of Oslo Region. There is a wide range in composition, and some have up to 95% of the Ae component. Most of the Na-rich pyroxenes (Ae > 90) are low in the Jd component (1.6 to 4.7%), and

Rare earth elements exploitation, geopolitical implications and raw materials trading

NASA Astrophysics Data System (ADS)

Chemin, Marie-Charlotte

2015-04-01

Rare earth elements (REE) correspond to seventeen elements of the periodic table. They are used in high technology, cracking, electric cars' magnet, metal alloy for batteries, and also in phone construction or ceramics for electronic card. REEs are an important resource for high technology. This project targets 16 years old students in the subject "personalized aid" and will last six weeks. The purpose of this project is to develop autonomy and research in groups for a transdisciplinary work. This project gathers knowledge in geology, geography and economics. During the first session students analyze the geology applications of the REE. They begin the analysis with learning the composition in different rocks such as basalt and diorite to make the link with crystallization. Then they compare it with adakite to understand the formation of these rocks. In the second session, they study REE exploitation. We can find them as oxides in many deposits. The principal concentrations of rare earth elements are associated with uncommon varieties of igneous rocks, such as carbonatites. They can use Qgis, to localize this high concentration. In the third session, they study the environmental costs of REE exploitation. Indeed, the exploitation produces thorium and carcinogenic toxins: sulphates, ammonia and hydrochloric acid. Processing one ton of rare earths produces 2,000 tons of toxic waste. This session focuses, first, on Baotou's region, and then on an example they are free to choose. In the fourth session, they study the geopolitical issues of REE with a focus on China. In fact this country is the largest producer of REE, and is providing 95% of the overall production. REE in China are at the center of a geopolitical strategy. In fact, China implements a sort of protectionism. Indeed, the export tax on REE is very high so, as a foreign company, it is financially attractive to establish a manufacturing subsidiary in China in order to use REE. As a matter of fact

Application of alkaline solid residue of electric arc furnace dust for neutralization/purification of electroplating wastewaters.

PubMed

Elez, Loris; Orescanin, Visnja; Sofilic, Tahir; Mikulic, Nenad; Ruk, Damir

2008-10-01

The purpose of this work was development of an appropriate procedure for the neutralization/purification of electroplating wastewater (EWW) with alkaline solid residue (ASR) by-product of the alkaline extraction of zinc and lead from electric arc furnace dust (EAFD). Removal efficiency of ASR at optimum purification conditions (pH 8 and mixing time; 20 minutes) for the elements Pb, Cr (VI), Cr (III), Fe, Ni, Cu and Zn were 94.92%, 97.58%, 99.59%, 99.48%, 97.25% and 99.97%, respectively. The concentrations of all elements in the purified wastewater were significantly lower in relation to the upper permissible limit for wastewaters suitable for discharge into the environment. The remaining waste mud was regenerated in the strong alkaline medium and successfully applied once again for the neutralization/purification of EWW. Removal efficiencies of heavy metals accomplished with regenerated waste mud were comparable to these achieved by original ASR. Elemental concentrations in the leachates of the waste mud were in accordance with regulated values.

A Density Functional Theory Study of Codoping Characteristics of Sulfur with Alkaline Earth in Delafossite CuAlO2

NASA Astrophysics Data System (ADS)

Liu, Qi-Jun; Qin, Han; Liu, Zheng-Tang

2016-04-01

The structural, electronic properties and formation energies of sulfur and alkaline earth codoped delafossite CuAlO2 have been investigated using the first-principles density functional theory calculations. Our results reveal that the volume of codoping systems increases with the increasing atomic radius of metal atoms. The formation energies under different growth conditions have been calculated, showing that the codoping systems are formed easily under O-rich growth conditions. Electronic band structures and density of states have been obtained. The decreased bandgaps, enhanced covalence and appearance of electron acceptors after codoping are all good for p-type conductivity. Supported by the National Natural Science Foundation of China under Grant Nos. 11347199, 51402244, and 11547311, the Specialized Research Fund for Doctoral Program of Higher Education of China under Grant No. 20130184120028, the Fundamental Research Fund for the Central Universities, China under Grant Nos. 2682014CX084, 2682014ZT30, and 2682014ZT31, and the fund of the State Key Laboratory of Solidification Processing in NWPU under Grant No. SKLSP201511

Novel alkaline earth copper germanates with ferro and antiferromagnetic S=1/2 chains

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

Brandao, Paula; Reis, Mario S; Gai, Zheng

Two new alkaline earth copper(II) germanates were hydrothermally synthesized: CaCuGeO4 center dot H2O (1) and BaCu2Ge3O9 center dot H2O (2), and their structures determined by single crystal X-ray diffraction. Compound (1) crystallizes in space group P2(1)/c with a=5.1320(2) angstrom, b=16.1637(5) angstrom, c=5.4818(2) angstrom, beta=102.609(2)degrees, V=443.76(3) angstrom(3) and Z=4. This copper germanate contains layers of composition [CuGeO4](infinity)(2-) comprising CuO4 square planes and GeO4 tetrahedra with calcium and water molecules in the inter-layer space. Compound (2) crystallizes in the Cmcm space group with a=5.5593(3) angstrom, b=10.8606(9) angstrom, c=13.5409(8) angstrom, V=817.56(9) angstrom(3) and Z=4. This structure contains GeO6 and CuO6 octahedra as wellmore » as GeO4 tetrahedra, forming a three-dimensional network of interconnecting six-membered ring channels. The magnetic susceptibility for both samples can be interpreted as S=1/2 chains, in agreement with the copper topology observed in the crystal structure. The susceptibility of (1) exhibits a Bonner-Fisher type behavior, resulting from antiferromagnetic intra-chain interactions without three-dimensional ordering down to 5 K-the lowest measured temperature. This observation, together with the absence of super-exchange paths between the copper chains, make this system particularly promising for the study of low dimensional magnetism. The magnetic properties of (2) show a very weak ferromagnetic near-neighbor interaction along the chain. In this compound a peak the chi T plot seems to indicate the onset of interchain antiferromagentic correlations. However, no ordering temperature is detected in the susceptibility data.« less

Toward understanding early Earth evolution: Prescription for approach from terrestrial noble gas and light element records in lunar soils

PubMed Central

Ozima, Minoru; Yin, Qing-Zhu; Podosek, Frank A.; Miura, Yayoi N.

2008-01-01

Because of the almost total lack of geological record on the Earth's surface before 4 billion years ago, the history of the Earth during this period is still enigmatic. Here we describe a practical approach to tackle the formidable problems caused by this lack. We propose that examinations of lunar soils for light elements such as He, N, O, Ne, and Ar would shed a new light on this dark age in the Earth's history and resolve three of the most fundamental questions in earth science: the onset time of the geomagnetic field, the appearance of an oxygen atmosphere, and the secular variation of an Earth–Moon dynamical system. PMID:19001263

Unravelling the sulphur isotope systematics of an alkaline magmatic province: implications for REE mineralization and exploration

NASA Astrophysics Data System (ADS)

Hutchison, W.; Finch, A.; Boyce, A.; Friis, H.; Borst, A. M.; Horsburgh, N. J.

2017-12-01

Some of the world's best alkaline rare earth element (REE) deposits are formed in magmatic systems that are sealed (i.e., those that are autometasomatised and maintain reducing conditions). Conversely, in open systems where oxidizing fluids infiltrate, it is commonly assumed that REE are redistributed over a wider (less concentrated) zone. Sulphur isotope fractionation is sensitive to variations in temperature and redox, and, although sulphide minerals are relatively abundant in alkaline systems, there have been few attempts to test these hypotheses and develop a sulphur isotope proxy for alkaline metasomatism and formation of associated REE deposits. The Gardar Rift Province in southern Greenland was volcanically active in two periods between 1300 and 1100 Ma and is an ideal natural laboratory to explore sulphur isotope systematics because a near-complete alkaline magmatic lineage is exposed. We present new δ34S from across the province with a particular focus on three alkaline systems (Ilímaussaq, Motzfeldt and Ivigtût) that also host major REE deposits. Primitive mafic rocks from regional Gardar dykes and lavas have a restricted range of δ34S between 0 and 3 ‰ and fractional crystallization imparts no observable change in δ34S. In a few cases high-δ34S rocks (>15 ‰) occur when intrusive units have assimilated local sedimentary crust (δ34S = 25 ‰). Most δ34S variation takes place in the roof zones of alkaline intrusions during late-magmatic and hydrothermal stages, and we identify clear differences between the complexes. At Ilímaussaq, where the magmatic series is exceptionally reduced (below QFM buffer), roof zone δ34S remains narrow (0-3 ‰). At Motzfeldt, a more open oxidizing roof zone (MH buffer), δ34S ranges from -12 ‰ in late-stage fluorite veins to +12 ‰ where local crust has been assimilated. Ivigtût is intermediate between these end-members varying between -5 to +5 ‰. The δ34S variations primarily relate to temperature and

Using Rare Earth Element (REE) tracers to identify perferential micro-sites of post-fire aeolian erosion

USDA-ARS?s Scientific Manuscript database

Plant communities in desert environments are spatially anisotropic. We applied Rare Earth Element (REE) tracers to different landscape positions of an anisotropic Northern Chihuahua Desert ecosystem in an effort to study preferential sediment source areas. We delineated three 0.5 m by 6 m plots of...

Structural and Dynamical Properties of Alkaline Earth Metal Halides in Supercritical Water: Effect of Ion Size and Concentration.

PubMed

Keshri, Sonanki; Tembe, B L

2017-11-22

Constant temperature-constant pressure molecular dynamics simulations have been performed for aqueous alkaline earth metal chloride [M 2+ -Cl - (M = Mg, Ca, Sr, and Ba)] solutions over a wide range of concentrations (0.27-5.55 m) in supercritical (SC) and ambient conditions to investigate their structural and dynamical properties. A strong influence of the salt concentration is observed on the ion-ion pair correlation functions in both ambient and SC conditions. In SC conditions, significant clustering is observed in the 0.27 m solution, whereas the reverse situation is observed at room temperature and this is also supported by the residence times of the clusters. The concentration and ion size (cation size) seem to have opposite effects on the average number of hydrogen bonds. The simulation results show that the self-diffusion coefficients of water, cations, and the chloride ion increase with increasing temperature, whereas they decrease with increasing salt concentration. The cluster size distribution shows a strong density dependence in both ambient and SC conditions. In SC conditions, cluster sizes display a near-Gaussian distribution, whereas the distribution decays monotonically in ambient conditions.

Rare Mineralogy in Alkaline Ultramafic Rocks, Western Kentucky Fluorspar District

NASA Astrophysics Data System (ADS)

Anderson, W.

2017-12-01

The alkaline ultramafic intrusive dike complex in the Western Kentucky Fluorspar District contains unusual mineralogy that was derived from mantle magma sources. Lamprophyre and peridotite petrologic types occur in the district where altered fractionated peridotites are enriched in Rare Earth Elements (REE) and some lamprophyre facies are depleted in incompatible elements. Unusual minerals in dikes, determined by petrography and X-ray diffraction, include schorlomite and andradite titanium garnets, astrophyllite, spodumene, niobium rutile, wüstite, fluoro-tetraferriphlogopite, villiaumite, molybdenite, and fluocerite, a REE-bearing fluoride fluorescent mineral. Mixing of MVT sphalerite ore fluids accompanies a mid-stage igneous alteration and intrusion event consistent with paragenetic studies. The presence of lithium in the spodumene and fluoro-tetraferriphlogopite suggests a lithium phase in the mineral fluids, and the presence of enriched REE in dikes and fluorite mineralization suggest a metasomatic event. Several of these rare minerals have never been described in the fluorspar district, and their occurrence suggests deep mantle metasomatism. Several REE-bearing fluoride minerals occur in the dikes and in other worldwide occurrences, they are usually associated with nepheline syenite and carbonatite differentiates. There is an early and late stage fluoride mineralization, which accompanied dike intrusion and was also analyzed for REE content. One fluorite group is enriched in LREE and another in MREE, which suggests a bimodal or periodic fluorite emplacement. Whole-rock elemental analysis was chondrite normalized and indicates that some of the dikes are slightly enriched in light REE and show a classic fractionation enrichment. Variations in major-element content; high titanium, niobium, and zirconium values; and high La/Yb, Zr/Y, Zr/Hf, and Nb/Ta ratios suggest metasomatized lithospheric-asthenospheric mantle-sourced intrusions. The high La/Yb ratios in some

Polymer monolithic capillary microextraction combined on-line with inductively coupled plasma MS for the determination of trace rare earth elements in biological samples.

PubMed

Zhang, Lin; Chen, Beibei; He, Man; Hu, Bin

2013-07-01

A rapid and sensitive method based on polymer monolithic capillary microextraction combined on-line with microconcentric nebulization inductively coupled plasma MS has been developed for the determination of trace/ultratrace rare earth elements in biological samples. For this purpose, the iminodiacetic acid modified poly(glycidyl methacrylate-trimethylolpropane trimethacrylate) monolithic capillary was prepared and characterized by SEM and FTIR spectroscopy. Factors affecting the extraction efficiency, such as sample pH, sample flow rate, sample/eluent volume, and coexisting ions were investigated in detail. Under the optimal conditions, the LODs for rare earth elements were in the range of 0.08 (Er) to 0.97 ng/L (Nd) with a sampling frequency of 8.5 h(-1), and the RSDs were between 1.5% (Sm) and 7.4% (Nd) (c = 20 ng/L, n = 7). The proposed method was successfully applied to the analysis of trace/ultratrace rare earth elements in human urine and serum samples, and the recoveries for the spiked samples were in the range of 82-105%. The developed method was simple, rapid, sensitive, and favorable for the analysis of trace/ultratrace rare earth elements in biological samples with limited sample volume. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Method to Recover Media Ligand Losses During Sorption of Rare Earth Elements from Simulated Geothermal Brines

DOE Data Explorer

Dean Stull

2016-05-24

This document describes the method and results of an in-situ experiment used to confirm that ligand bleed from a sorptive media can be contained. The experiment focused on maintaining the media's sorption of rare earth elements (REE) obtained from a simulated geothermal brine doped with known mineral concentrations.

Rare-earth elements in the Permian Phosphoria Formation: Paleo proxies of ocean geochemistry

USGS Publications Warehouse

Piper, D.Z.; Perkins, R.B.; Rowe, H.D.

2007-01-01

The geochemistry of deposition of the Meade Peak Member of the Phosphoria Formation (MPM) in southeast Idaho, USA, a world-class sedimentary phosphate deposit of Permian age that extends over 300,000 km2, is ascertained from its rare earth element (REE) composition. Ratios of REE:Al2O3 suggest two sources-seawater and terrigenous debris. The seawater-derived marine fraction identifies bottom water in the Phosphoria Sea as O2-depleted, denitrifying (suboxic) most of the time, and seldom sulfate-reducing (anoxic). This interpretation is supported by earlier research that showed progressively greater ratios in the marine sediment fraction of Cr:Ni>V:Ni???Mo:Ni, relative to their ratios in seawater; for which marine Cr, V, and Mo can have a dominantly O2-depleted bottom-water source and Ni a photic-zone, largely algal, source. The water chemistry was maintained by a balance between bacterial oxidation of organic matter settling through the water column, determined largely by primary productivity in the photic zone, and the flux of oxidants into the bottom water via advection of seawater from the open ocean. Samples strongly enriched in carbonate fluorapatite, the dominant REE host mineral, have variable Er/Sm, Tm/Sm, and Yb/Sm ratios. Their distribution may represent greater advection of seawater between the Phosphoria Sea and open ocean during deposition of two ore zones than a center waste and greater upwelling of nutrient-enriched water into the photic zone. However, the mean rate of deposition of marine Ni, a trace nutrient of algae, and PO43-, a limiting nutrient, indicate that primary productivity was probably high throughout the depositional history. An alternative interpretation of the variable enrichments of Er, Tm, and Yb, relative to Sm, is that they may reflect temporally variable carbonate alkalinity of open-ocean seawater in Permian time. A more strongly negative Ce anomaly for all phosphatic units than the Ce anomaly of modern pelletal phosphate is

Rare-earth elements in the Permian Phosphoria Formation: Paleo proxies of ocean geochemistry

NASA Astrophysics Data System (ADS)

Piper, D. Z.; Perkins, R. B.; Rowe, H. D.

2007-06-01

The geochemistry of deposition of the Meade Peak Member of the Phosphoria Formation (MPM) in southeast Idaho, USA, a world-class sedimentary phosphate deposit of Permian age that extends over 300,000 km 2, is ascertained from its rare earth element (REE) composition. Ratios of REE:Al 2O 3 suggest two sources—seawater and terrigenous debris. The seawater-derived marine fraction identifies bottom water in the Phosphoria Sea as O 2-depleted, denitrifying (suboxic) most of the time, and seldom sulfate-reducing (anoxic). This interpretation is supported by earlier research that showed progressively greater ratios in the marine sediment fraction of Cr:Ni>V:Ni≫Mo:Ni, relative to their ratios in seawater; for which marine Cr, V, and Mo can have a dominantly O 2-depleted bottom-water source and Ni a photic-zone, largely algal, source. The water chemistry was maintained by a balance between bacterial oxidation of organic matter settling through the water column, determined largely by primary productivity in the photic zone, and the flux of oxidants into the bottom water via advection of seawater from the open ocean. Samples strongly enriched in carbonate fluorapatite, the dominant REE host mineral, have variable Er/Sm, Tm/Sm, and Yb/Sm ratios. Their distribution may represent greater advection of seawater between the Phosphoria Sea and open ocean during deposition of two ore zones than a center waste and greater upwelling of nutrient-enriched water into the photic zone. However, the mean rate of deposition of marine Ni, a trace nutrient of algae, and PO 43-, a limiting nutrient, indicate that primary productivity was probably high throughout the depositional history. An alternative interpretation of the variable enrichments of Er, Tm, and Yb, relative to Sm, is that they may reflect temporally variable carbonate alkalinity of open-ocean seawater in Permian time. A more strongly negative Ce anomaly for all phosphatic units than the Ce anomaly of modern pelletal phosphate

Seychelles alkaline suite records the culmination of Deccan Traps continental flood volcanism

NASA Astrophysics Data System (ADS)

Owen-Smith, T. M.; Ashwal, L. D.; Torsvik, T. H.; Ganerød, M.; Nebel, O.; Webb, S. J.; Werner, S. C.

2013-12-01

Silhouette and North Islands in the Seychelles represent an alkaline plutonic-volcanic complex, dated at 63 to 63.5 Ma by U-Pb zircon and 40Ar/39Ar methods. This magmatism coincides with the final stages of the cataclysmic Deccan Traps continental flood volcanism in India (67 to 63 Ma), and thus a causal link has been suggested. Recent reconstructions have placed the Seychelles islands adjacent to the Laxmi Ridge and at the western margin of the Réunion mantle plume at the time of formation of the complex. Here we present geochemical evidence in support of the notion that the Seychelles alkaline magmatism was initiated by the peripheral activity of the Réunion mantle plume and is thus part of the Deccan magmatic event. Positive εNd (0.59 to 3.76) and εHf (0.82 to 6.79) and initial Sr of 0.703507 to 0.705643 at 65 Ma indicate derivation of the Seychelles alkaline magmas from a Réunion-like mantle source with an additional minor enriched component, suggesting entrainment of sub-continental lithospheric mantle. The similarity in trace element composition between the Seychelles suite and Deccan alkaline felsic and mafic rocks provides additional evidence for a common mantle source for the Seychelles and Deccan magmatism. Furthermore, we demonstrate the role of fractional crystallisation in the evolution of the alkaline suite. Modelling using major elements suggests that fractional crystallisation and varying degrees of accumulation of olivine, plagioclase, ilmenite, clinopyroxene, alkali feldspar and apatite can describe the spectrum of rock types, from gabbro, through syenite, to granite.

Rare Earth Element Concentrations from Wells at the Don A. Campbell Geothermal Plant, Nevada

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

Fowler, Andrew; Zierenberg, Robert

* Requires permission of originators for use. Rare earth element concentrations in thermal springs from the wells at the Don A. Campbell geothermal plant, Nevada. Samples taken from geothermal wells 85-11, 65-11, 54-11, and 64-11. Includes pH and concentrations for Cerium, Dysprosium, Erbium, Europium, Gadolinium, Holmium, Lanthanum, Lutetium, Neodymium, Praseodymium, Samarium, Terbium, Thulium, Yttrium, and Ytterbium. Samples from Don A. Campbell, Nevada collected on October 14, 2016.

Highly siderophile elements in Earth's mantle as a clock for the Moon-forming impact.

PubMed

Jacobson, Seth A; Morbidelli, Alessandro; Raymond, Sean N; O'Brien, David P; Walsh, Kevin J; Rubie, David C

2014-04-03

According to the generally accepted scenario, the last giant impact on Earth formed the Moon and initiated the final phase of core formation by melting Earth's mantle. A key goal of geochemistry is to date this event, but different ages have been proposed. Some argue for an early Moon-forming event, approximately 30 million years (Myr) after the condensation of the first solids in the Solar System, whereas others claim a date later than 50 Myr (and possibly as late as around 100 Myr) after condensation. Here we show that a Moon-forming event at 40 Myr after condensation, or earlier, is ruled out at a 99.9 per cent confidence level. We use a large number of N-body simulations to demonstrate a relationship between the time of the last giant impact on an Earth-like planet and the amount of mass subsequently added during the era known as Late Accretion. As the last giant impact is delayed, the late-accreted mass decreases in a predictable fashion. This relationship exists within both the classical scenario and the Grand Tack scenario of terrestrial planet formation, and holds across a wide range of disk conditions. The concentration of highly siderophile elements (HSEs) in Earth's mantle constrains the mass of chondritic material added to Earth during Late Accretion. Using HSE abundance measurements, we determine a Moon-formation age of 95 ± 32 Myr after condensation. The possibility exists that some late projectiles were differentiated and left an incomplete HSE record in Earth's mantle. Even in this case, various isotopic constraints strongly suggest that the late-accreted mass did not exceed 1 per cent of Earth's mass, and so the HSE clock still robustly limits the timing of the Moon-forming event to significantly later than 40 Myr after condensation.

Galileo Earth approach navigation using connected-element interferometer phase-delay tracking

NASA Technical Reports Server (NTRS)

Thurman, S. W.

1990-01-01

The application of a Connected-Element Interferometer (CEI) to the navigation of the Galileo spacecraft during its encounter with Earth in December 1990 is investigated. A CEI tracking demonstration is planned for the week of November 11 through 18, 1990, from 27 days to 20 days prior to Earth encounter on December 8. During this period, the spacecraft will be tracked daily with Deep Space Network Stations 13 and 15 at Goldstone. The purpose of this work is twofold: first, to establish and define the navigation performance expected during the tracking demonstration and, second, to study, in a more general sense, the sensitivity of orbit demonstration results obtained with CEI to the data density within CEI tracking passes and to important system parameters, such as baseline orientation errors and the phase-delay measurement accuracy. Computer simulation results indicate that the use of CEI data, coupled with conventional range and Doppler data, may reduce the uncertainty in the declination of the spacecraft's incoming trajectory by 15 to 66 percent compared with the operational solution using range and Doppler data only. The level of improvement depends upon the quantity and quality of the CEI data.

Exploring the anisotropic Kondo model in and out of equilibrium with alkaline-earth atoms

NASA Astrophysics Data System (ADS)

Kanász-Nagy, Márton; Ashida, Yuto; Shi, Tao; Moca, Cǎtǎlin Paşcu; Ikeda, Tatsuhiko N.; Fölling, Simon; Cirac, J. Ignacio; Zaránd, Gergely; Demler, Eugene A.

2018-04-01

We propose a scheme to realize the Kondo model with tunable anisotropy using alkaline-earth atoms in an optical lattice. The new feature of our setup is Floquet engineering of interactions using time-dependent Zeeman shifts, that can be realized either using state-dependent optical Stark shifts or magnetic fields. The properties of the resulting Kondo model strongly depend on the anisotropy of the ferromagnetic interactions. In particular, easy-plane couplings give rise to Kondo singlet formation even though microscopic interactions are all ferromagnetic. We discuss both equilibrium and dynamical properties of the system that can be measured with ultracold atoms, including the impurity spin susceptibility, the impurity spin relaxation rate, as well as the equilibrium and dynamical spin correlations between the impurity and the ferromagnetic bath atoms. We analyze the nonequilibrium time evolution of the system using a variational non-Gaussian approach, which allows us to explore coherent dynamics over both short and long timescales, as set by the bandwidth and the Kondo singlet formation, respectively. In the quench-type experiments, when the Kondo interaction is suddenly switched on, we find that real-time dynamics shows crossovers reminiscent of poor man's renormalization group flow used to describe equilibrium systems. For bare easy-plane ferromagnetic couplings, this allows us to follow the formation of the Kondo screening cloud as the dynamics crosses over from ferromagnetic to antiferromagnetic behavior. On the other side of the phase diagram, our scheme makes it possible to measure quantum corrections to the well-known Korringa law describing the temperature dependence of the impurity spin relaxation rate. Theoretical results discussed in our paper can be measured using currently available experimental techniques.

Compilation of Rare Earth Element Analyses from US Geothermal Fields and Mid Ocean Ridge Hydrothermal Vents

DOE Data Explorer

Andrew Fowler

2015-10-01

Compilation of rare earth element and associated major and minor dissolved constituent analytical data for USA geothermal fields and global seafloor hydrothermal vents. Data is in original units. Reference to and use of this data should be attributed to the original authors and publications according to the provisions outlined therein.

Investigation of recovery and recycling of rare earth elements from waste fluorescent lamp phosphors

NASA Astrophysics Data System (ADS)

Eduafo, Patrick Max

Characterization techniques and experimental measurements were used to evaluate a process for recycling rare earth elements (REEs) from spent fluorescent lamp phosphors. QEMSCAN analysis revealed that over 60% of the rare earth bearing minerals was less than 10 microm. A representative sample of the as-received feed contained 14.59 wt% total rare earth elements (TREE) and upon sieving to below 75 microm, the grade increased to 19.60 wt% REE with 98.75% recovery. Based on experimental work, a new process for extracting the chief REEs from end of life fluorescent lamps has been developed. The proposed flowsheet employs a three-stage leaching and precipitation process for selective extraction and recovery of the REEs. Hydrochloric acid was used as lixiviant in batch leach experiments on the phosphor powder. The maximum extraction obtained was 100% for both yttrium and europium under the following leaching conditions: 2.5 M HCl, 70°C, 1 hour, 180 g/L and 600 rpm. However, the solubility of cerium, lanthanum and terbium remained low at these conditions. Kinetic data of the leaching of yttrium and europium showed best fit to the logarithmic rate expression of the empirical model of leaching. Activation energy was calculated to be 77.49 kJ/mol for Y and 72.75 kJ/mol for Eu in the temperature range of 298 to 343 K. Precipitation tests demonstrate that at least 50% excess the stoichiometric amount of oxalic acid is needed to recover yttrium and europium efficiently to produce a pure (Y, Eu) mixed oxide. Total recovery of the REEs was achieved even at very low pH or without any base added. Over 99% pure mixed rare earth oxide at 99% recovery has been attained. An economic assessment of the developed process using operating and capital cost have be undertaken and based on the analysis of the three economic scenarios, two are economic and one is non-economic.

Rare earth elements as a fingerprint of soil components solubilization

NASA Astrophysics Data System (ADS)

Davranche, M.; Grybos, M.; Gruau, G.; Pédrot, M.; Dia, A.

2009-04-01

The retention of rare earth element (REE) in the soil profile are mainly controlled by three factors, (i) the stability of the primary REE-carrying minerals, (ii) the presence of secondary phases as clays and Fe- and Mn-oxyhydroxides and (ii) the concentration of colloidal organic matter (OM). Considering that each soil phases (mineral or organic) displays (ii) various surface properties, such as specific area, surface sites density and nature and (ii) their own REE distribution inherited from the rock weathering, their mobilization through various chemical reactions (dissolution, colloidal release….) may involve the development of various shaped REE patterns in the soil solutions. REE fractionation from the different soil phases may therefore be used to identify the response of the soil system to a particular chemical process such as reductive and/or acidic dissolution. To test this purpose, an organic-rich wetland soil sample was incubated under anaerobic condition at both pH 5 and uncontrolled pH. The REE patterns developed in the soil solution were then compared to the REE patterns obtained through either aerobic at pH 3 and 7 incubations or a chemical reduction experiment (using hydroxylamine). REE patterns in anaerobic and aerobic at pH 7 experiments exhibited the same middle rare earth element (MREE) downward concavity significant of the complexation of REE with soil OM. By contrast, under acidic condition, the REE pattern exhibited a positive Eu anomaly due to the dissolution of soil feldspar. Finally, REE pattern obtained from the chemical reducing experiment showed an intermediary flat shape corresponding to a mixing between the soil organic and mineral phases dissolution. The comparison of the various REE pattern shapes allowed to conclude that (i) biological reduction of wetland soil involved amorphous Fe(III) colloids linked to OM and, (ii) that the REE mobility was controlled by the dynamic of OM in wetland soil. They also evidence the potential of

Normalized rare earth elements in water, sediments, and wine: identifying sources and environmental redox conditions

USGS Publications Warehouse

Piper, David Z.; Bau, Michael

2013-01-01

The concentrations of the rare earth elements (REE) in surface waters and sediments, when normalized on an element-by-element basis to one of several rock standards and plotted versus atomic number, yield curves that reveal their partitioning between different sediment fractions and the sources of those fractions, for example, between terrestrial-derived lithogenous debris and seawater-derived biogenous detritus and hydrogenous metal oxides. The REE of ancient sediments support their partitioning into these same fractions and further contribute to the identification of the redox geochemistry of the sea water in which the sediments accumulated. The normalized curves of the REE that have been examined in several South American wine varietals can be interpreted to reflect the lithology of the bedrock on which the vines may have been grown, suggesting limited fractionation during soil development.

Prophylactic treatment with alkaline phosphatase in cardiac surgery induces endogenous alkaline phosphatase release.

PubMed

Kats, Suzanne; Brands, Ruud; Hamad, Mohamed A Soliman; Seinen, Willem; Scharnhorst, Volkher; Wulkan, Raymond W; Schönberger, Jacques P; Oeveren, Wim van

2012-02-01

Laboratory and clinical data have implicated endotoxin as an important factor in the inflammatory response to cardiopulmonary bypass. We assessed the effects of the administration of bovine intestinal alkaline phosphatase (bIAP), an endotoxin detoxifier, on alkaline phosphatase levels in patients undergoing coronary artery bypass grafting. A total of 63 patients undergoing coronary artery bypass grafting were enrolled and prospectively randomized. Bovine intestinal alkaline phosphatase (n=32) or placebo (n=31) was administered as an intravenous bolus followed by continuous infusion for 36 hours. The primary endpoint was to evaluate alkaline phosphatase levels in both groups and to find out if administration of bIAP to patients undergoing CABG would lead to endogenous alkaline phosphatase release. No significant adverse effects were identified in either group. In all the 32 patients of the bIAP-treated group, we found an initial rise of plasma alkaline phosphatase levels due to bolus administration (464.27±176.17 IU/L). A significant increase of plasma alkaline phosphatase at 4-6 hours postoperatively was observed (354.97±95.00 IU/L) as well. Using LHA inhibition, it was shown that this second peak was caused by the generation of tissue non specific alkaline phosphatase (TNSALP-type alkaline phosphatase). Intravenous bolus administration plus 8 hours continuous infusion of alkaline phosphatase in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass results in endogenous alkaline phosphatase release. This endogenous alkaline phosphatase may play a role in the immune defense system.

Rare earth elements in fine-grained sediments of major rivers from the high-standing island of Taiwan

NASA Astrophysics Data System (ADS)

Li, Chuan-Shun; Shi, Xue-Fa; Kao, Shuh-Ji; Liu, Yan-Guang; Lyu, Hua-Hua; Zou, Jian-Jun; Liu, Sheng-Fa; Qiao, Shu-Qing

2013-06-01

Thirty-eight sediment samples from 15 primary rivers on Taiwan were retrieved to characterize the rare earth element (REE) signature of fluvial fine sediment sources. Compared to the three large rivers on the Chinese mainland, distinct differences were observed in the REE contents, upper continental crust normalized patterns and fractionation factors of the sediment samples. The average REE concentrations of the Taiwanese river sediments are higher than those of the Changjiang and Huanghe, but lower than the Zhujiang. Light rare earth elements (LREEs) are enriched relative to heavy rare earth elements (HREEs) with ratios from 7.48 to 13.03. We found that the variations in (La/Lu)UCC-(Gd/Lu)UCC and (La/Yb)UCC-(Gd/Yb)UCC are good proxies for tracing the source sediments of Taiwanese and Chinese rivers due to their distinguishable values. Our analyses indicate that the REE compositions of Taiwanese river sediments were primarily determined by the properties of the bedrock, and the intensity of chemical weathering in the drainage areas. The relatively high relief and heavy rainfall also have caused the REEs in the fluvial sediments from Taiwan to be transported to the estuaries down rivers from the mountains, and in turn delivered nearly coincidently to the adjacent seas by currents and waves. Our studies suggest that the REE patterns of the river sediments from Taiwan are distinguishable from those from the other sources of sediments transported into the adjacent seas, and therefore are useful proxies for tracing the provenances and dispersal patterns of sediments, as well as paleoenvironmental changes in the marginal seas.

Constructing and Screening a Metagenomic Library of a Cold and Alkaline Extreme Environment.

PubMed

Glaring, Mikkel A; Vester, Jan K; Stougaard, Peter

2017-01-01

Natural cold or alkaline environments are common on Earth. A rare combination of these two extremes is found in the permanently cold (less than 6 °C) and alkaline (pH above 10) ikaite columns in the Ikka Fjord in Southern Greenland. Bioprospecting efforts have established the ikaite columns as a source of bacteria and enzymes adapted to these conditions. They have also highlighted the limitations of cultivation-based methods in this extreme environment and metagenomic approaches may provide access to novel extremophilic enzymes from the uncultured majority of bacteria. Here, we describe the construction and screening of a metagenomic library of the prokaryotic community inhabiting the ikaite columns.

Complementary rare earth element patterns in unique achondrites, such as ALHA 77005 and shergottites, and in the earth

NASA Technical Reports Server (NTRS)

Ma, M.-S.; Schmitt, R. A.; Laul, J. C.

1982-01-01

Abundances of major, minor, and trace elements are determined in the Antarctic achondrite Allan Hills (ALHA) 77005 via sequential instrumental and radiochemical neutron activation analysis. The rare earth element (REE) abundances of ALHA 77005 reveal a unique chondritic normalized pattern; that is, the REEs are nearly unfractionated from La to Pr at approximately 1.0X chondrites, monotonically increased from Pr to Gd at approximately 3.4X with no Eu anomaly, nearly unfractionated from Gd and Ho and monotonically decreased from Ho to Lu at approximately 2.2X. It is noted that this unique REE pattern of ALHA 77005 can be modeled by a melting process involving a continuous melting and progressive partial removal of melt from a light REE enriched source material. In a model of this type, ALHA 77005 could represent either a crystallized cumulate from such a melt or the residual source material. Calculations show that the parent liquids for the shergottites could also be derived from a light REE enriched source material similar to that for ALHA 77005.

Prebiotic Synthesis of Glycine from Ethanolamine in Simulated Archean Alkaline Hydrothermal Vents

NASA Astrophysics Data System (ADS)

Zhang, Xianlong; Tian, Ge; Gao, Jing; Han, Mei; Su, Rui; Wang, Yanxiang; Feng, Shouhua

2017-12-01

Submarine hydrothermal vents are generally considered as the likely habitats for the origin and evolution of early life on Earth. In recent years, a novel hydrothermal system in Archean subseafloor has been proposed. In this model, highly alkaline and high temperature hydrothermal fluids were generated in basalt-hosted hydrothermal vents, where H2 and CO2 could be abundantly provided. These extreme conditions could have played an irreplaceable role in the early evolution of life. Nevertheless, sufficient information has not yet been obtained for the abiotic synthesis of amino acids, which are indispensable components of life, at high temperature and alkaline condition. This study aims to propose a new method for the synthesis of glycine in simulated Archean submarine alkaline vent systems. We investigated the formation of glycine from ethanolamine under conditions of high temperature (80-160 °C) and highly alkaline solutions (pH = 9.70). Experiments were performed in an anaerobic environment under mild pressure (0.1-8.0 MPa) at the same time. The results suggested that the formation of glycine from ethanolamine occurred rapidly and efficiently in the presence of metal powders, and was favored by high temperatures and high pressures. The experiment provides a new pathway for prebiotic glycine formation and points out the phenomenal influence of high-temperature alkaline hydrothermal vents in origin of life in the early ocean.

Prebiotic Synthesis of Glycine from Ethanolamine in Simulated Archean Alkaline Hydrothermal Vents.

PubMed

Zhang, Xianlong; Tian, Ge; Gao, Jing; Han, Mei; Su, Rui; Wang, Yanxiang; Feng, Shouhua

2017-12-01

Submarine hydrothermal vents are generally considered as the likely habitats for the origin and evolution of early life on Earth. In recent years, a novel hydrothermal system in Archean subseafloor has been proposed. In this model, highly alkaline and high temperature hydrothermal fluids were generated in basalt-hosted hydrothermal vents, where H 2 and CO 2 could be abundantly provided. These extreme conditions could have played an irreplaceable role in the early evolution of life. Nevertheless, sufficient information has not yet been obtained for the abiotic synthesis of amino acids, which are indispensable components of life, at high temperature and alkaline condition. This study aims to propose a new method for the synthesis of glycine in simulated Archean submarine alkaline vent systems. We investigated the formation of glycine from ethanolamine under conditions of high temperature (80-160 °C) and highly alkaline solutions (pH = 9.70). Experiments were performed in an anaerobic environment under mild pressure (0.1-8.0 MPa) at the same time. The results suggested that the formation of glycine from ethanolamine occurred rapidly and efficiently in the presence of metal powders, and was favored by high temperatures and high pressures. The experiment provides a new pathway for prebiotic glycine formation and points out the phenomenal influence of high-temperature alkaline hydrothermal vents in origin of life in the early ocean.

Rare earths, other trace elements and iron in Luna 20 samples.

NASA Technical Reports Server (NTRS)

Helmke, P. A.; Blanchard, D. P.; Jacobs, J. W.; Haskin, L.; Haskin, A.

1973-01-01

The results of the analysis by neutron activation of six samples from the Luna 20 mission and one sample of less than 1 mm fines from Apollo 16 are reported. The concentrations of the rare-earth elements (REE) in the samples of fines from Luna 20 and Apollo 16 are less than those found for corresponding materials from the mare areas but a negative Eu anomaly is still present. The concentrations of the REE in fines from Luna 20 are only about two-thirds as great as in the sample of Apollo 16 fines, but the concentration of Co, Sc and Cr are greater by factors ranging from 1.5 to 2.3.

Light rare earth element depletion during Deepwater Horizon blowout methanotrophy.

PubMed

Shiller, A M; Chan, E W; Joung, D J; Redmond, M C; Kessler, J D

2017-09-04

Rare earth elements have generally not been thought to have a biological role. However, recent work has demonstrated that the light REEs (LREEs: La, Ce, Pr, and Nd) are essential for at least some methanotrophs, being co-factors in the XoxF type of methanol dehydrogenase (MDH). We show here that dissolved LREEs were significantly removed in a submerged plume of methane-rich water during the Deepwater Horizon (DWH) well blowout. Furthermore, incubation experiments conducted with naturally methane-enriched waters from hydrocarbon seeps in the vicinity of the DWH wellhead also showed LREE removal concurrent with methane consumption. Metagenomic sequencing of incubation samples revealed that LREE-containing MDHs were present. Our field and laboratory observations provide further insight into the biochemical pathways of methanotrophy during the DWH blowout. Additionally, our results are the first observations of direct biological alteration of REE distributions in oceanic systems. In view of the ubiquity of LREE-containing MDHs in oceanic systems, our results suggest that biological uptake of LREEs is an overlooked aspect of the oceanic geochemistry of this group of elements previously thought to be biologically inactive and an unresolved factor in the flux of methane, a potent greenhouse gas, from the ocean.

Origin of middle rare earth element enrichments in acid waters of a Canadian high Arctic lake.

NASA Astrophysics Data System (ADS)

Johannesson, Kevin H.; Zhou, Xiaoping

1999-01-01

-Middle rare earth element (MREE) enriched rock-normalized rare earth element (REE) patterns of a dilute acidic lake (Colour Lake) in the Canadian High Arctic, were investigated by quantifying whole-rock REE concentrations of rock samples collected from the catchment basin, as well as determining the acid leachable REE fraction of these rocks. An aliquot of each rock sample was leached with 1 N HNO 3 to examine the readily leachable REE fraction of each rock, and an additional aliquot was leached with a 0.04 M NH 2OH · HCl in 25% (v/v) CH 3COOH solution, designed specifically to reduce Fe-Mn oxides/oxyhydroxides. Rare earth elements associated with the leachates that reacted with clastic sedimentary rock samples containing petrographically identifiable Fe-Mn oxide/oxyhydroxide cements and/or minerals/amorphous phases, exhibited whole-rock-normalized REE patterns similar to the lake waters, whereas whole-rock-normalized leachates from mafic igneous rocks and other clastic sedimentary rocks from the catchment basin differed substantially from the lake waters. The whole-rock, leachates, and lake water REE data support acid leaching or dissolution of MREE enriched Fe-Mn oxides/oxyhydroxides contained and identified within some of the catchment basin sedimentary rocks as the likely source of the unique lake water REE patterns. Solution complexation modelling of the REEs in the inflow streams and lake waters indicate that free metal ions (e.g., Ln 3+, where Ln = any REE) and sulfate complexes (LnSO 4+) are the dominant forms of dissolved REEs. Consequently, solution complexation reactions involving the REEs during weathering, transport to the lake, or within the lake, cannot be invoked to explain the MREE enrichments observed in the lake waters.

Elements and inorganic ions as source tracers in recent Greenland snow

NASA Astrophysics Data System (ADS)

Lai, Alexandra M.; Shafer, Martin M.; Dibb, Jack E.; Polashenski, Chris M.; Schauer, James J.

2017-09-01

Atmospheric transport of aerosols leads to deposition of impurities in snow, even in areas of the Arctic as remote as Greenland. Major ions (e.g. Na+, Ca2+, NH4+, K+, SO42-) are frequently used as tracers for common aerosol sources (e.g. sea spray, dust, biomass burning, anthropogenic emissions). Trace element data can supplement tracer ion data by providing additional information about sources. Although many studies have considered either trace elements or major ions, few have reported both. This study determined total and water-soluble concentrations of 31 elements (Al, As, Ca, Cd, Ce, Co, Cr, Dy, Eu, Fe, Gd, K, La, Mg, Mn, Na, Nb, Nd, Pb, Pr, S, Sb, Si, Sm, Sn, Sr, Ti, V, U, Y, Zn) in shallow snow pits at 22 sampling sites in Greenland, along a transect from Summit Station to sites in the northwest. Black carbon (BC) and inorganic ions were measured in colocated samples. Sodium, which is typically used as a tracer of sea spray, did not appear to have any non-marine sources. The rare earth elements, alkaline earth elements (Mg, Ca, Sr), and other crustal elements (Fe, Si, Ti, V) were not enriched above crustal abundances relative to Al, indicating that these elements are primarily dust sourced. Calculated ratios of non-sea salt Ca (nssCa) to estimated dust mass affirm the use of nssCa as a dust tracer, but suggest up to 50% uncertainty in that estimate in the absence of other crustal element data. Crustal enrichment factors indicated that As, Cd, Pb, non-sea-salt S, Sb, Sn, and Zn were enriched in these samples, likely by anthropogenic sources. Principal component analysis indicated more than one crustal factor, and a variety of factors related to anthropogenically enriched elements. Analysis of trace elements alongside major tracer ions does not change interpretation of ion-based source attribution for sources that are well-characterized by ions, but is valuable for assessing uncertainty in source attribution and identifying sources not represented by major ions.

Distribution and Geochemistry of Rare-Earth Elements in Rivers of Southern and Eastern Primorye (Far East of Russia)

NASA Astrophysics Data System (ADS)

Chudaev, O. V.; Bragin, I. V.; A, Kharitonova N.; Chelnokov, G. A.

2016-03-01

The distribution and geochemistry of rare earth elements (REE) in anthropogenic, technogenic and natural surface waters of southern and eastern Primorye, Far East of Russia, are presented in this study. The obtained results indicated that most of REE (up to 70%) were transported as suspended matter, ratio between dissolved and suspended forms varing from the source to the mouth of rivers. It is shown that all REE (except Ce) in the source of the rivers are predominantly presented in dissolved form, however, the content of light and heavy REE is different. Short-term enrichment of light rare earth elements (LREE) caused by REE-rich runoff from waste dumps and mining is neutralized by the increase in river flow rate. Rivers in urban areas are characterized by high content of LREE in dissolved form and very low in suspended one.

Contemporaneous trachyandesitic and calc-alkaline volcanism of the Huerto Andesite, San Juan Volcanic Field, Colorado, USA

USGS Publications Warehouse

Parat, F.; Dungan, M.A.; Lipman, P.W.

2005-01-01

Locally, voluminous andesitic volcanism both preceded and followed large eruptions of silicic ash-flow tuff from many calderas in the San Juan volcanic field. The most voluminous post-collapse lava suite of the central San Juan caldera cluster is the 28 Ma Huerto Andesite, a diverse assemblage erupted from at least 5-6 volcanic centres that were active around the southern margins of the La Garita caldera shortly after eruption of the Fish Canyon Tuff. These andesitic centres are inferred, in part, to represent eruptions of magma that ponded and differentiated within the crust below the La Garita caldera, thereby providing the thermal energy necessary for rejuvenation and remobilization of the Fish Canyon magma body. The multiple Huerto eruptive centres produced two magmatic series that differ in phenocryst mineralogy (hydrous vs anhydrous assemblages), whole-rock major and trace element chemistry and isotopic compositions. Hornblende-bearing lavas from three volcanic centres located close to the southeastern margin of the La Garita caldera (Eagle Mountain - Fourmile Creek, West Fork of the San Juan River, Table Mountain) define a high-K calc-alkaline series (57-65 wt % SiO2) that is oxidized, hydrous and sulphur rich. Trachyandesitic lavas from widely separated centres at Baldy Mountain-Red Lake (western margin), Sugarloaf Mountain (southern margin) and Ribbon Mesa (20 km east of the La Garita caldera) are mutually indistinguishable (55-61 wt % SiO2); they are characterized by higher and more variable concentrations of alkalis and many incompatible trace elements (e.g. Zr, Nb, heavy rare earth elements), and they contain anhydrous phenocryst assemblages (including olivine). These mildly alkaline magmas were less water rich and oxidized than the hornblende-bearing calc-alkaline suite. The same distinctions characterize the voluminous precaldera andesitic lavas of the Conejos Formation, indicating that these contrasting suites are long-term manifestations of San Juan

A comprehensive analysis of the content of heavy rare-earth elements and platinum in snow samples to assess the ecological hazard of air pollution in urban areas

NASA Astrophysics Data System (ADS)

Vinokurov, S. F.; Tarasova, N. P.; Trunova, A. N.; Sychkova, V. A.

2017-07-01

Snow samples from the territory of the Setun River Valley Wildlife Sanctuary are analyzed for the content of rare-earth elements, heavy metals, and other hazardous elements by the inductively coupled plasma mass-spectrometry method. The changes in the concentrations of rare-earth elements, Pt, Pd, and indicator ratios of elements in the solid fractions of snow are revealed. A trend toward a decrease in the content of several elements northeastward of the Moscow Ring Road (MRR) is established. The level of seasonal atmospheric contamination of the area under study is assessed, and a possible source is identified.

Bioleaching of rare earth and radioactive elements from red mud using Penicillium tricolor RM-10.

PubMed

Qu, Yang; Lian, Bin

2013-05-01

The aim of this work is to investigate biological leaching of rare earth elements (REEs) and radioactive elements from red mud, and to evaluate the radioactivity of the bioleached red mud used for construction materials. A filamentous, acid-producing fungi named RM-10, identified as Penicillium tricolor, is isolated from red mud. In our bioleaching experiments by using RM-10, a total concentration of 2% (w/v) red mud under one-step bioleaching process was generally found to give the maximum leaching ratios of the REEs and radioactive elements. However, the highest extraction yields are achieved under two-step bioleaching process at 10% (w/v) pulp density. At pulp densities of 2% and 5% (w/v), red mud processed under both one- and two-step bioleaching can meet the radioactivity regulations in China. Copyright © 2013 Elsevier Ltd. All rights reserved.

Determination of rare earth elements in tomato plants by inductively coupled plasma mass spectrometry techniques.

PubMed

Spalla, S; Baffi, C; Barbante, C; Turetta, C; Turretta, C; Cozzi, G; Beone, G M; Bettinelli, M

2009-10-30

In recent years identification of the geographical origin of food has grown more important as consumers have become interested in knowing the provenance of the food that they purchase and eat. Certification schemes and labels have thus been developed to protect consumers and genuine producers from the improper use of popular brand names or renowned geographical origins. As the tomato is one of the major components of what is considered to be the healthy Mediterranean diet, it is important to be able to determine the geographical origin of tomatoes and tomato-based products such as tomato sauce. The aim of this work is to develop an analytical method to determine rare earth elements (RRE) for the control of the geographic origin of tomatoes. The content of REE in tomato plant samples collected from an agricultural area in Piacenza, Italy, was determined, using four different digestion procedures with and without HF. Microwave dissolution with HNO3 + H2O2 proved to be the most suitable digestion procedure. Inductively coupled plasma quadrupole mass spectrometry (ICPQMS) and inductively coupled plasma sector field plasma mass spectrometry (ICPSFMS) instruments, both coupled with a desolvation system, were used to determine the REE in tomato plants in two different laboratories. A matched calibration curve method was used for the quantification of the analytes. The detection limits (MDLs) of the method ranged from 0.03 ng g(-1) for Ho, Tm, and Lu to 2 ng g(-1) for La and Ce. The precision, in terms of relative standard deviation on six replicates, was good, with values ranging, on average, from 6.0% for LREE (light rare earth elements) to 16.5% for HREE (heavy rare earth elements). These detection limits allowed the determination of the very low concentrations of REE present in tomato berries. For the concentrations of REE in tomato plants, the following trend was observed: roots > leaves > stems > berries. Copyright 2009 John Wiley & Sons, Ltd.

X-ray Diffraction Studies of the Structure and Thermochemistry of Alkaline-Earth Oxide-Coated Thermionic Cathodes

NASA Technical Reports Server (NTRS)

Karikari, E. K.; Bassey, E.; Wintucky, Edwin G.

1998-01-01

NASA LeRC has a broad, active cathode technology development program in which both experimental and theoretical studies are being employed to further development of thermionic cathodes for use as electron sources in vacuum devices for communications and other space applications. One important type of thermionic cathode under development is the alkaline-earth oxide-coated (BaO, SrO, CaO) cathode. Significant improvements in the emission characteristics of this cathode have been obtained through modification of the chemical composition and morphology of the oxide coating, with the best result thus far coming from the addition of In2O3 and Sc2O3. Whereas the In2O3 produces a finer, more uniform particle structure, the exact chemical state and role of the Sc2O3 in the emission enhancement is unknown. The purpose of this cooperative agreement is to combine the studies of the surface chemistry and electron emission at NASA LeRC of chemically modified oxide coatings with a study of the thermochemistry and crystal structure using X-ray diffraction equipment and expertise at Clark Atlanta University (CAU). The study at CAU is intended to provide the description and understanding of the structure and thermochemistry needed for further improvement and optimization of the modified coatings. A description of the experimental procedure, preliminary X-ray diffraction test results, together with the design of an ultrahigh vacuum chamber necessary for high temperature thermochemistry studies will be presented.

Miocene calc-alkaline heritage in the pliocene postcollisional volcanism of monte arci (Sardinia, Italy)

NASA Astrophysics Data System (ADS)

Cioni, Roberto; Clocchiatti, Robert; Di Paola, Giovanni M.; Santacroce, Roberto; Tonarini, Sonia

1982-10-01

At Monte Arci alkaline (hawaiites to trachytes), subalkaline with a marked calc-alkaline character (basalts to dacites) and rhyolitic lavas were erupted almost simultaneously in Late Pliocene time. Major- and trace-element chemistry, microprobe mineralogy and isotopic data suggest a partial melting origin for both rhyolites and subalkaline rocks. Different sources are however inferred for two rock series: homogeneous, calc-alkaline in nature for subalkaline rocks; unhomogeneous, richer in 87Sr, for rhyolitic ones. Crystal fractionation differentiation from subcrustal alkali-basalts should have been the main process in the genesis of alkaline rocks. Large-scale contaminations with rhyolitic and/or alkaline rocks are evident in many of these lavas. Such a complicated magmatic association characterizes an area where volcanism related to post-collisional tensional movements in Pliocene time superimposes to Middle Miocene calc-alkaline basic volcanism related to previous subduction processes. The Pliocene volcanic history of Monte Arci emphasizes the influence of the paleogeodynamic environment on the nature of magmas erupted in post-continental collision areas, that are frequently difficult to arrange in the usual schemas connecting magma composition with tectonic setting.

Rare earth and precious elements in the urban sewage sludge and lake surface sediments under anthropogenic influence in the Republic of Benin.

PubMed

Yessoufou, Arouna; Ifon, Binessi Edouard; Suanon, Fidèle; Dimon, Biaou; Sun, Qian; Dedjiho, Comlan Achille; Mama, Daouda; Yu, Chang-Ping

2017-11-09

Nowadays, sewage sludge and water bodies are subjected to heavy pollution due to rapid population growth and urbanization. Heavy metal pollution represents one of the main challenges threatening our environment and the ecosystem. The present work aims to evaluate the contamination state of the sewage sludge and lake sediments in the Republic of Benin. Twenty metallic elements including 15 rare earth elements (Eu, Sb, Cs, Nd, Pr, Gd, La, Ce, Tb, Sm, Dy, Ho, Eu, Yb, and Lu) and five precious elements (Ag, Au, Pd, Pt, and Ru) were investigated using inductive plasma-mass spectrometry. Results showed broad range concentrations of the elements. Ce, La, and Nd were present in both sediments and sewage sludge at concentrations ranging 5.80-41.30 mg/kg dry matter (DM), 3.23-15.60 mg/kg DM, and 2.74-19.26 mg/kg DM, respectively. Pr, Sm, Gd, Tb, Dy, Eu, Er, Yb, Cs, Ho, and Tm concentrations were lower (0.02-5.94 mg/kg DM). Among precious elements, Ag was detected at the highest concentration in all sites (0.43-4.72 mg/kg DM), followed by Pd (0.20-0.57 mg/kg DM) and Au (0.01-0.57 mg/kg DM). Ru and Pt concentrations were < 0.20 mg/kg DM in all samples. Pollution indices and enrichment factor indicated a strong to severe enrichment of the elements, mainly Ce and precious elements in both sediments and sewage sludge. This revealed a growing anthropogenic input which was also implied by principal component analysis. The evaluation of pollution loading index (PLI) indicated a moderate to strong contamination (0.12 ≤ PLI ≤ 0.58; 37 ≤ PLI ≤ 114, respectively, for rare earth elements and precious elements), while the degree of contamination indicated a moderate polymetallic contamination for rare earth elements and significant contamination for precious elements.

Trace Element Inputs to the Upper West Pacific from Nd Isotopes and Rare Earth Elements

NASA Astrophysics Data System (ADS)

Behrens, M. K.; Pahnke, K.; Schnetger, B.; Brumsack, H. J.

2015-12-01

Neodymium isotopes (143Nd/144Nd, expressed as ɛNd) and rare earth element (REE) concentrations in the ocean trace water mass transport and margin-seawater exchange processes. The distinct ɛNd and REE signatures of the lithogenic components of margin sediments of the West Pacific allow characterization of trace element inputs to the Pacific Ocean. We present dissolved ɛNdand REE concentrations from twelve vertical profiles of a transect from South Korea to Fiji. Near South Korea, surface waters are marked by unradiogenic ɛNd (as low as -7.3), high REE concentrations (e.g., Nd = 15.3 pmol/kg) and low salinity. Towards the open ocean, these parameters gradually change towards typical Pacific open ocean values (ɛNd = -3.3, [Nd] = 5.55 pmol/kg). Subsurface waters show REE depletions, followed by the typical REE increase with increasing water depth. These distributions indicate trace element input near South Korea and enhanced subsurface scavenging, as indicated by strong heavy REE to light REE fractionation. In the tropical West Pacific (10°N-15°S), high surface and subsurface water ɛNd values (+0.7) and positive Eu anomalies trace the influence of volcanic islands. Yet, absolute REE concentrations are extremely low at these depths (e.g., Nd = 2.77 pmol/kg). Using shale-normalized Nd/Er and Ho/Dy ratios, that show a much stronger surface to subsurface decrease in coastal waters compared to the open ocean, we suggest enhanced scavenging in this area. Eastward flowing intermediate waters (NPIW, AAIW) have ɛNd values up to +1.9 (NPIW) and +3.7 (AAIW) higher than those entering the tropical West Pacific from north and south, respectively. Modified ɛNd at intermediate depths and no change in REE patterns suggest that boundary exchange along volcanic island margins modifies the seawater ɛNd without changing the REE budget.

The origin of life in alkaline hydrothermal vents

NASA Astrophysics Data System (ADS)

Sojo, V.; Herschy, B.; Whicher, A.; Camprubí, E.; Lane, N.

2016-12-01

The origin of life remains one of Science's greatest unresolved questions. The answer will no doubt involve almost all the basic disciplines, including Physics, Chemistry, Astronomy, Geology, and Biology. Chiefly, it is the link between the latter two that must be elucidated: how geochemistry gave rise to biochemistry. Serpentinizing systems such as alkaline hydrothermal vents offer the most robust combination of conditions to have hosted the origin of life on the early Earth, while bearing many parallels to modern living cells. Stark gradients of concentration, pH, oxidation/reduction, and temperature provided the ability to synthesise and concentrate organic products, drive polymerisation reactions, and develop an autotrophic lifestyle independent of foreign sources of organics. In the oxygen-depleted waters of the Hadean, alkaline vents would have acted as electrochemical flow reactors, in which alkaline fluids saturated in H2 mixed with the relatively acidic CO2-rich waters of the ocean, through interconnected micropores made of thin inorganic walls containing catalytic Fe(Ni)S minerals. Perhaps not coincidentally, the unit cells of these Fe(Ni)S minerals closely resemble the active sites of crucial ancestral bioenergetic enzymes. Meanwhile, differences in pH across the thin barriers produced natural proton gradients similar to those used for carbon fixation in modern archaea and bacteria. At the earliest stages, the problem of the origin of life is the problem of the origin of carbon fixation. I will discuss work over the last decade that suggests several possible hypotheses for how simple one-carbon molecules could have given rise to more complex organics, particularly within a serpentinizing alkaline hydrothermal vent. I will discuss the perplexing differences in carbon and energy metabolism in methanogenic archaea and acetogenic bacteria, thought to be the earliest representatives of each domain, to propose a possible ancestral mechanism of CO2 reduction in

Alkaline igneous rocks of Magnet Cove, Arkansas: Mineralogy and geochemistry of syenites

USGS Publications Warehouse

Flohr, M.J.K.; Ross, M.

1990-01-01

Syenites from the Magnet Cove alkaline igneous complex form a diverse mineralogical and geochemical suite. Compositional zoning in primary and late-stage minerals indicates complex, multi-stage crystallization and replacement histories. Residual magmatic fluids, rich in F, Cl, CO2 and H2O, reacted with primary minerals to form complex intergrowths of minerals such as rinkite, fluorite, V-bearing magnetite, F-bearing garnet and aegirine. Abundant sodalite and natrolite formed in pegmatitic segregations within nepheline syenite where Cl- and Na-rich fluids were trapped. During autometasomatism compatible elements such as Mn, Ti, V and Zr were redistributed on a local scale and concentrated in late-stage minerals. Early crystallization of apatite and perovskite controlled the compatible behavior of P and Ti, respectively. The formation of melanite garnet also affected the behaviour of Ti, as well as Zr, Hf and the heavy rare-earth elements. Pseudoleucite syenite and garnet-nepheline syenite differentiated along separate trends, but the two groups are related to the same parental magma by early fractionation of leucite, the presumed precursor of intergrowths of K-feldspar and nepheline. The Diamond Jo nepheline syenite group defines a different differentiation trend. Sphene-nepheline syenite, alkali syenite and several miscellaneous nepheline syenites do not consistently plot with the other syenite groups or each other on element and oxide variation diagrams, indicating that they were derived from still other parental syenite magmas. Mineral assemblages indicate that relatively high f{hook};O2, at or above the fayalite-magnetite-quartz buffer, prevailed throughout the crystallization history of the syenites. ?? 1990.

Characterization of metal binding sites onto biochar using rare earth elements as a fingerprint.

PubMed

Pourret, Olivier; Houben, David

2018-02-01

The ability of biochar to immobilize metals relies on the amount of functional groups at its surface but the contribution of each functional groups (e.g. carboxylic, phenolic) to metal bonding is poorly known. Using a new approach based on previous works on rare earth element (REE) interactions with humic substances, we aim at elucidating the relative contribution of these binding sites to metal sorption under various conditions (i.e. pH and ionic strengths, IS). Using batch experiments, REE sorption onto biochar was analyzed from pH 3 to 9 and IS 10 -1 mol/L to 10 -3 mol/L. Rare earth element patterns show a Middle REE (MREE) downward concavity at acidic pH and low ionic strength. These patterns are in good agreement with existing datasets quantifying REE binding with humic substances. Indeed, the MREE downward concavity displayed by REE-biochar complexation pattern compares well with REE patterns with various organic compounds. This similarity in the REE complexation pattern shapes suggests that carboxylic groups are the main binding sites of REE in biochar. Overall, our results indicate that the strength of the metal bonding with biochar increases when pH and IS increase, suggesting that biochar is more efficient for long-term metal immobilization at near neutral pH and high ionic strength.

Rare earth element analysis indicates micropollutants in an urban estuary

NASA Astrophysics Data System (ADS)

Mohajerin, T. J.; Johannesson, K. H.; Kolker, A.; Burdige, D. J.; Chevis, D.

2011-12-01

Rare earth element analysis of Bayou Bienvenue waters shows anomalously high gadolinium, Gd, concentrations relative to its nearest neighbors in the REE series, europium and terbium. The anomalously high Gd concentrations indicate anthropogenic input from waste-water treatment plants in the area as anthropogenic Gd input can be traced back to its use as a contrast agent in magnetic resonance imaging in hospitals. Others have shown that anomalously high levels of Gd in natural waters are likely to be associated with other micropollutants that also occur in hospital effluent and that are not removed in the wastewater treatment process, including pharmaceuticals in the form of steroids, antihistamines, and antibiotics. Estuaries serve as many important ecological roles and have been shown to act as a filter for pollutants. To better understand the transport, biogeochemical cycling, and ultimate fate of trace elements in estuaries, I collected surface water samples from Bayou Bienvenue, a wetland triangle that covers an area of 427 acres directly adjacent to New Orleans, Louisiana. Water samples from Bayou Bienvenue were collected along the salinity gradient and subsequently filtered through progressively smaller pore-size filters. The resulting fractions were analyzed for trace element concentions, including the REEs, by magnetic sector ICP-MS. The attached figure shows the Gd anomaly present in the particulate (>0.45μm) fraction. Upper continental crust (UCC)-normalized plots of colloidal REEs (0.02μm - 0.45μm) fraction is lacking this anomaly indicating anthropogenic Gd is found chiefly in the particulate fraction in Bayou Bienvenue. No clear relationship between Gd concentration and salinity was apparent.

Advanced Characterization of Rare Earth Elements in Coal Utilization Byproducts

NASA Astrophysics Data System (ADS)

Verba, C.; Scott, M.; Dieterich, M.; Poston, J.; Collins, K.

2016-12-01

Rare earth elements (REE) in various forms (e.g., crystalline mineral phases; adsorbed/absorbed state on and into organic macerals, neoformed glass from flyash or bottom ash) from domestic feedstocks such as coal deposits to coal utilization byproducts (CUB) have the potential to reduce foreign REE dependence and increase domestic resource security. Characterization is critical for understanding environmental risks related to their fate and transport as well as determining the most practical and economical techniques for concentrating the REE and converting them into chemical stocks for manufacturing. Several complementary electron microscopy (SEM-EDS, EPMA-WDS, FIB-SEM, cathodoluminescence, and XRD) and post image processing techniques were used to understand REE transition from coal to CUB. Sites of interest were identified and imaged and respective elemental x-ray maps acquired and montaged. Pixel classification of SEM imagers was completed using image analysis techniques to quantify the distribution of REE associated features. Quantitative elemental analysis of phases were completed using EMPA-WDS followed by FIB-SEM. The FIB-SEM results were reconstructed into 3D volumes and features of interest (e.g. monazite) were analyzed to determine the structure and volumetric estimation of REEs and thus predict detrital REE phases to ICP-MS results. Trace minerals were identified as pyrite, zircon, REE-phosphates' (monazite, xenotime), and barite within the coal tailings. In CUB, amorphous aluminosilicates, iron oxide cenospheres, and calcium oxides were present; monazite appear to be unaltered and unaffected by the combustion process in these samples. Thermal decomposition may have occurred due to presence of detrital zircon and xenotime and subsequent thin Ca-oxide coating enriched in trace REEs.

Fast preconcentration of trace rare earth elements from environmental samples by di(2-ethylhexyl)phosphoric acid grafted magnetic nanoparticles followed by inductively coupled plasma mass spectrometry detection

NASA Astrophysics Data System (ADS)

Yan, Ping; He, Man; Chen, Beibei; Hu, Bin

2017-10-01

In this work, di(2-ethylhexyl)phosphoric acid (P204) grafted magnetic nanoparticles were synthesized by fabricating P204 onto Fe3O4@TiO2 nanoparticles based on Lewis acid-base interaction between Ti and phosphate group under weakly acidic condition. The prepared Fe3O4@TiO2@P204 nanoparticles exhibited excellent selectivity for rare earth elements, and good anti-interference ability. Based on it, a method of magnetic solid phase extraction (MSPE) combined with inductively coupled plasma mass spectrometry (ICP-MS) was developed for fast preconcentration and determination of trace rare earth elements in environmental samples. Under the optimal conditions, the detection limits of rare earth elements were in the range of 0.01 (Tm)-0.12 (Nd) ng L- 1 with an enrichment factor of 100-fold, and the relative standard deviations ranged from 4.9 (Pr) to 10.7% (Er). The proposed method was successfully applied to the determination of rare earth elements in environmental samples, including river water, lake water, seawater and sediment.

Effect of light elements on the sound velocities in solid iron: Implications for the composition of Earth's core

NASA Astrophysics Data System (ADS)

Badro, James; Fiquet, Guillaume; Guyot, François; Gregoryanz, Eugene; Occelli, Florent; Antonangeli, Daniele; d'Astuto, Matteo

2007-02-01

We measured compressional sound velocities in light element alloys of iron (FeO, FeSi, FeS, and FeS2) at high-pressure by inelastic X-ray scattering. This dataset provides new mineralogical constraints on the composition of Earth's core, and completes the previous sets formed by the pressure-density systematics for these compounds. Based on the combination of these datasets and their comparison with radial seismic models, we propose an average composition model of the Earth's core. We show that the incorporation of small amounts of silicon or oxygen is compatible with geophysical observations and geochemical abundances. The effect of nickel on the calculated light element contents is shown to be negligible. The preferred core model derived from our measurements is an inner core which contains 2.3 wt.% silicon and traces of oxygen, and an outer core containing 2.8 wt.% silicon and around 5.3 wt.% oxygen.

Uranium chloride extraction of transuranium elements from LWR fuel

DOEpatents

Miller, William E.; Ackerman, John P.; Battles, James E.; Johnson, Terry R.; Pierce, R. Dean

1992-01-01

A process of separating transuranium actinide values from uranium values present in spent nuclear oxide fuels containing rare earth and noble metal fission products as well as other fission products is disclosed. The oxide fuel is reduced with Ca metal in the presence of Ca chloride and a U-Fe alloy which is liquid at about 800.degree. C. to dissolve uranium metal and the noble metal fission product metals and transuranium actinide metals and rare earth fission product metals leaving Ca chloride having CaO and fission products of alkali metals and the alkali earth metals and iodine dissolved therein. The Ca chloride and CaO and the fission products contained therein are separated from the U-Fe alloy and the metal values dissolved therein. The U-Fe alloy having dissolved therein reduced metals from the spent nuclear fuel is contacted with a mixture of one or more alkali metal or alkaline earth metal halides selected from the class consisting of alkali metal or alkaline earth metal and Fe or U halide or a combination thereof to transfer transuranium actinide metals and rare earth metals to the halide salt leaving the uranium and some noble metal fission products in the U-Fe alloy and thereafter separating the halide salt and the transuranium metals dissolved therein from the U-Fe alloy and the metals dissolved therein.

Uranium chloride extraction of transuranium elements from LWR fuel

DOEpatents

Miller, W.E.; Ackerman, J.P.; Battles, J.E.; Johnson, T.R.; Pierce, R.D.

1992-08-25

A process of separating transuranium actinide values from uranium values present in spent nuclear oxide fuels containing rare earth and noble metal fission products as well as other fission products is disclosed. The oxide fuel is reduced with Ca metal in the presence of Ca chloride and a U-Fe alloy which is liquid at about 800 C to dissolve uranium metal and the noble metal fission product metals and transuranium actinide metals and rare earth fission product metals leaving Ca chloride having CaO and fission products of alkali metals and the alkali earth metals and iodine dissolved therein. The Ca chloride and CaO and the fission products contained therein are separated from the U-Fe alloy and the metal values dissolved therein. The U-Fe alloy having dissolved therein reduced metals from the spent nuclear fuel is contacted with a mixture of one or more alkali metal or alkaline earth metal halides selected from the class consisting of alkali metal or alkaline earth metal and Fe or U halide or a combination thereof to transfer transuranium actinide metals and rare earth metals to the halide salt leaving the uranium and some noble metal fission products in the U-Fe alloy and thereafter separating the halide salt and the transuranium metals dissolved therein from the U-Fe alloy and the metals dissolved therein. 1 figure.

Effects of rare earth elements and REE-binding proteins on physiological responses in plants.

PubMed

Liu, Dongwu; Wang, Xue; Chen, Zhiwei

2012-02-01

Rare earth elements (REEs), which include 17 elements in the periodic table, share chemical properties related to a similar external electronic configuration. REEs enriched fertilizers have been used in China since the 1980s. REEs could enter the cell and cell organelles, influence plant growth, and mainly be bound with the biological macromolecules. REE-binding proteins have been found in some plants. In addition, the chlorophyll activities and photosynthetic rate can be regulated by REEs. REEs could promote the protective function of cell membrane and enhance the plant resistance capability to stress produced by environmental factors, and affect the plant physiological mechanism by regulating the Ca²⁺ level in the plant cells. The focus of present review is to describe how REEs and REE-binding proteins participate in the physiological responses in plants.

COST-EFFECTIVE RARE EARTH ELEMENT RECYCLING PROCESS FROM INDUSTRIAL SCRAP AND DISCARDED ELECTRONIC PRODUCTS TO VALUABLE MAGNETIC ALLOYS AND PERMANENT MAGNETS - PHASE II

EPA Science Inventory

Rare earth element (REE) based Nd-Fe-B and Sm-Co permanent magnets have been widely used because of their excellent magnetic properties. The applications of Nd-Fe-B and Sm-Co rare earth permanent magnets include hybrid electric vehicles (HEVs), power generators for wind tur...

Ir and Rare Earth's Elements determination by Neutron Activation Analysis and ICP - MS in soil samples

NASA Astrophysics Data System (ADS)

Salvini, A.; Cattadori, C.; Broggini, C.; Cagnazzo, M.; Ori, Gian Gabriele; Nisi, S.; Borio, A.; Manera, S.

2006-05-01

The platinum metals depleted in the earth's crust are relative to their cosmic abundance; concentration of these elements in sediments may thus indicate influxes of extraterrestrial material. Analysis of these parameters are done easily by Neutron Activation Analysis (NAA) and comparative results with ICP-MS technique show a good match. Results, adjust parameters and limits of this method will be displayed in tables.

Neutron Activation Analysis of the Rare Earth Elements (REE) - With Emphasis on Geological Materials

NASA Astrophysics Data System (ADS)

Stosch, Heinz-Günter

2016-08-01

Neutron activation analysis (NAA) has been the analytical method of choice for rare earth element (REE) analysis from the early 1960s through the 1980s. At that time, irradiation facilitieswere widely available and fairly easily accessible. The development of high-resolution gamma-ray detectors in the mid-1960s eliminated, formany applications, the need for chemical separation of the REE from the matrix material, making NAA a reliable and effective analytical tool. While not as precise as isotopedilution mass spectrometry, NAA was competitive by being sensitive for the analysis of about half of the rare earths (La, Ce, Nd, Sm, Eu, Tb, Yb, Lu). The development of inductively coupled plasma mass spectrometry since the 1980s, together with decommissioning of research reactors and the lack of installation of new ones in Europe and North America has led to the rapid decline of NAA.

Characterization of Rare Earth Element Minerals in Coal Utilization Byproducts

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

Montross, Scott N.; Verba, Circe A.; Collins, Keith

The United States currently produces over 100 million tons of coal utilization byproducts (CUB) per year in the form of fly ash, bottom ash, slag, and flue gas (American Coal Ash Association (ACCA), 2015). But this “waste material” also contains potentially useful levels of rare earth elements (REE). Rare earth elements are crucial for many existing and emerging technologies, but the U.S. lacks a domestic, sustainable REE source. Our project explored the possibility of developing a supply of REEs for U.S. technologies by extracting REEs from CUBs. This work offers the potential to reduce our dependence on other countries formore » supply of these critical elements (NETL, REE 2016 Project Portfolio). Geologic and diagenetic history, industrial preparation methods, and the specific combustion process all play major roles in the composition of CUB. During combustion, inorganic mineral phases of coal particles are fluidized at temperatures higher than 1400oC, so inorganic mineral materials are oxidized, fused, disintegrated, or agglomerated into larger spherical and amorphous (non-crystalline) particles. The original mineralogy of the coal-containing rock and heating/cooling of the material significantly affects the composition and morphology of the particles in the combustion byproduct (Kutchko and Kim, 2006). Thus, different types of coal/refuse/ash must be characterized to better understand mineral evolution during the combustion process. Our research focused on developing a working model to address how REE minerals behave during the combustion process: this research should help determine the most effective engineering methods for extracting REEs from CUBs. We used multimodal imaging and image processing techniques to characterize six rock and ash samples from different coal power plants with respect to morphology, grain size, presence of mineral phases, and elemental composition. The results of these characterization activities provided thresholds for

Trace elements and rare earth elements in wet deposition of Lijiang, Mt. Yulong region, southeastern edge of the Tibetan Plateau.

PubMed

Guo, Junming; Kang, Shichang; Huang, Jie; Sillanpää, Mika; Niu, Hewen; Sun, Xuejun; He, Yuanqing; Wang, Shijing; Tripathee, Lekhendra

2017-02-01

In order to investigate the compositions and wet deposition fluxes of trace elements and rare earth elements (REEs) in the precipitation of the southeastern edge of the Tibetan Plateau, 38 precipitation samples were collected from March to August in 2012 in an urban site of Lijiang city in the Mt. Yulong region. The concentrations of most trace elements and REEs were higher during the non-monsoon season than during the monsoon season, indicating that the lower concentrations of trace elements and REEs observed during monsoon had been influenced by the dilution effect of increased precipitation. The concentrations of trace elements in the precipitation of Lijiang city were slightly higher than those observed in remote sites of the Tibetan Plateau but much lower than those observed in the metropolises of China, indicating that the atmospheric environment of Lijiang city was less influenced by anthropogenic emissions, and, as a consequence, the air quality was still relatively good. However, the results of enrichment factor and principal component analysis revealed that some anthropogenic activities (e.g., the increasing traffic emissions from the rapid development of tourism) were most likely important contributors to trace elements, while the regional/local crustal sources rather than anthropogenic activities were the predominant contributors to the REEs in the wet deposition of Lijiang city. Our study was relevant not only for assessing the current status of the atmospheric environment in the Mt. Yulong region, but also for specific management actions to be implemented for the control of atmospheric inputs and the health of the environment for the future. Copyright © 2016. Published by Elsevier B.V.

Recovery of rare earth elements from the sulfothermophilic red alga Galdieria sulphuraria using aqueous acid.

PubMed

Minoda, Ayumi; Sawada, Hitomi; Suzuki, Sonoe; Miyashita, Shin-ichi; Inagaki, Kazumi; Yamamoto, Takaiku; Tsuzuki, Mikio

2015-02-01

The demand for rare earth elements has increased dramatically in recent years because of their numerous industrial applications, and considerable research efforts have consequently been directed toward recycling these materials. The accumulation of metals in microorganisms is a low-cost and environmentally friendly method for the recovery of metals present in the environment at low levels. Numerous metals, including rare earth elements, can be readily dissolved in aqueous acid, but the efficiency of metal biosorption is usually decreased under the acidic conditions. In this report, we have investigated the use of the sulfothermophilic red alga Galdieria sulphuraria for the recovery of metals, with particular emphasis on the recovery of rare earth metals. Of the five different growth conditions investigated where G. sulphuraria could undergo an adaptation process, Nd(III), Dy(III), and Cu(II) were efficiently recovered from a solution containing a mixture of different metals under semi-anaerobic heterotrophic condition at a pH of 2.5. G. sulphuraria also recovered Nd(III), Dy(III), La(III), and Cu(II) with greater than 90% efficiency at a concentration of 0.5 ppm. The efficiency remained unchanged at pH values in the range of 1.5-2.5. Furthermore, at pH values in the range of 1.0-1.5, the lanthanoid ions were collected much more efficiently into the cell fractions than Cu(II) and therefore successfully separated from the Cu(II) dissolved in the aqueous acid. Microscope observation of the cells using alizarin red suggested that the metals were accumulating inside of the cells. Experiments using dead cells suggested that this phenomenon was a biological process involving specific activities within the cells.

Major and trace element partitioning between dissolved and particulate phases in Antarctic surface snow.

PubMed

Grotti, M; Soggia, F; Ardini, F; Magi, E

2011-09-01

In order to provide a new insight into the Antarctic snow chemistry, partitioning of major and trace elements between dissolved and particulate (i.e. insoluble particles, >0.45 μm) phases have been investigated in a number of coastal and inland snow samples, along with their total and acid-dissolvable (0.5% nitric acid) concentrations. Alkaline and alkaline-earth elements (Na, K, Ca, Mg, Sr) were mainly present in the dissolved phase, while Fe and Al were predominantly associated with the particulate matter, without any significant difference between inland and coastal samples. On the other hand, partitioning of trace elements depended on the sampling site position, showing a general decrease of the particulate fraction by moving from the coast to the plateau. Cd, Cu, Pb and Zn were for the most part in the dissolved phase, while Cr was mainly associated with the particulate fraction. Co, Mn and V were equally distributed between dissolved and particulate phases in the samples collected from the plateau and preferentially associated with the particulate in the coastal samples. The correlation between the elements and the inter-sample variability of their concentration significantly decreased for the plateau samples compared to the coastal ones, according to a change in the relative contribution of the metal sources and in good agreement with the estimated marine and crustal enrichment factors. In addition, samples from the plateau were characterised by higher enrichment factors of anthropogenic elements (Cd, Cr, Cu, Pb and Zn), compared to the coastal area. Finally, it was observed that the acid-dissolvable metal concentrations were generally lower than the total concentration values, showing that the acid treatment can dissolve only a given fraction of the metal associated with the particulate (<20% for iron and aluminium).

Dual spectra band emissive Eu2+/Mn2+ co-activated alkaline earth phosphates for indoor plant growth novel phosphor converted-LEDs.

PubMed

Yun, Young Jun; Kim, Jin Kyu; Ju, Ji Young; Choi, Seul Ki; Park, Woon Ik; Suh, Jae Yong; Jung, Ha-Kyun; Kim, Yongseon; Choi, Sungho

2017-05-10

This paper reports designing a novel single composition blue/red color illuminating phosphor followed by fabricating "smart" agricultural/horticultural LED lighting. Color-tunable Eu 2+ /Mn 2+ co-activated alkaline earth phosphates, Na(Sr,Ba)PO 4 and Ca 3 Mg 3 (PO 4 ) 4 , are considered, and the stable doping sites for the corresponding activators are identified by using first-principle DFT calculations. We can realize the designated color purity with stable thermal quenching preserved luminescence behavior is induced by the Eu 2+ center positioned at different coordination states with intermixed Sr 2+ /Ba 2+ sites in Na(Sr,Ba)PO 4 hosts. Moreover, we demonstrate that the resultant LED lighting adopting the proposed novel phosphor composition stimulates the enhanced photosynthesis reaction for indoor hydroponics plants, such as oats and onions, which is superior to the narrow line emission band induced by the mixture of conventional red/green/blue LEDs. Thus, using the color-tunable single composition luminescent material may produce an innovative energy-efficient artificial lighting for indoor plant growth.

Pleiotropic effects of mutations involved in the regulation of Escherichia coli K-12 alkaline phosphatase.

PubMed

Morris, H; Schlesinger, M J; Bracha, M; Yagil, E

1974-08-01

Induction of alkaline phosphatase in wild-type Escherichia coli K-12 leads to the appearance of three new proteins in addition to alkaline phosphatase in the periplasmic space of the bacteria. These proteins are detected in autoradiograms of sodium dodecyl sulfate-acrylamide gel electropherograms of extracts from cells labeled with [(35)S]methionine. Studies with constitutive mutants defective in the three genes phoS, phoT, and phoR that have been shown to regulate alkaline phosphatase synthesis indicate that the three periplasmic proteins are coregulated with alkaline phosphatase. A mutant that has a deletion in the alkaline phosphatase structural gene phoA produces the three proteins, but a newly discovered mutant phoB that has a defect in the expression of alkaline phosphatase fails to produce the three proteins. phoB mutants are shown here to be unable to make detectable amounts of alkaline phosphatase polypeptides, as measured by immunoprecipitins or acrylamide gel electropherograms. On the basis of these results we suggest a new model for the regulation of alkaline phosphatase biosynthesis. In this model, a ternary complex composed of phoB(+) and phoR(+) gene products and an internal metabolite functions as a positive control element to regulate the transcription of several cistrons coding for periplasmic proteins.