Investigating the stability of cathode materials for rechargeable lithium ion batteries

Science.gov (United States)

Huang, Yiqing

Lithium ion batteries are widely used in portable electronic devices and electric vehicles. However, safety is one of the most important issues for the Li-ion batteries' use. Some cathode materials, such as LiCoO 2, are thermally unstable in the charged state. Upon decomposition these cathode materials release O2, which could react with organic electrolyte, leading to a thermal runaway. Thus understanding the stability of the cathode materials is critical to the safety of lithium ion batteries. Olivine-type LiMnPO4 is a promising cathode material for lithium ion batteries because of its high energy density. We have revealed the critical role of carbon in the stability and thermal behaviour of olivine MnPO 4 obtained by chemical delithiation of LiMnPO4. (Li)MnPO 4 samples with various particle sizes and carbon contents were studied. Carbon-free LiMnPO4 obtained by solid state synthesis in O 2 becomes amorphous upon delithiation. Small amounts of carbon (0.3 wt.%) help to stabilize the olivine structure, so that completely delithiated crystalline olivine MnPO4 can be obtained. Larger amount of carbon (2 wt.%) prevents full delithiation. Heating in air, O2, or N 2 results in structural disorder (cathode materials and the electrolyte. The thermal stability of electrochemically delithiated Li0.1N 0.8C0.15Al0.05O2 (NCA), FePO4 (FP), Mn0.8Fe0.2PO4 (MFP), hydrothermally synthesized VOPO4, LiVOPO4 and electrochemically lithiated Li2VOPO4 is investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis, coupled with mass spectrometry (TGA-MS). The thermal stability is found in the order: NCA< VOPO4< MFP< FP=LiVOPO4=Li2VOPO4. Sealed capsule high pressure experiments show a phase transformation of VOPO4 → HVOPO4 → H2VOPO4 when VOPO4 reacts with electrolyte (1 M LiPF6 in EC: DMC=1:1) between 200 and 300 °C. Finally, we characterize the lithium storage and release mechanism of V2O5 aerogels by x-ray photoelectron spectroscopy (XPS). We study the

Raman and FTIR spectroscopy of methane in olivine

Science.gov (United States)

Smith, A.; Oze, C.; Rossman, G. R.; Celestian, A. J.

2017-12-01

Olivine has been proposed to be a direct source of methane (CH4) in serpentinization systems and experiments. Here, Raman and Fourier Transform Infrared (FTIR) spectroscopy were used to verify the presence and abundance of CH4 in olivine samples from nine localities, including the San Carlos olivine. Raman analyses did not identify any methane in the olivine samples. As olivine is orthorhombic, three polarized FTIR spectra were obtained for the olivine samples. No methane was detected in any of the olivine samples using FTIR. Overall, olivine investigated in this study does not appear to be a primary source of methane.

The formation of phosphoran olivine and stanfieldite from the pyrometamorphic breakdown of apatite in slags from a prehistoric ritual immolation site (Goldbichl, Igls, Tyrol, Austria)

Science.gov (United States)

Schneider, Philipp; Tropper, Peter; Kaindl, Reinhard

2013-04-01

In this study we report P-rich olivine and the tric-calcium phosphate (TCP) stanfieldite in partially molten quartzphyllites from the ritual immolation site at the Goldbichl, near Innsbruck in the Tyrol, Austria. During partial melting, foamy patches of dark glassy material formed at the surface of the rocks and also as layers within the rocks. The pyrometamorphic rocks contain mostly the mineral assemblage olivine + orthopyroxene + plagioclase + spinel + glass. During the investigation of slag samples from this prehistoric ritual immolation site, extremely P-rich, apatite-bearing micro-domains were found. In these domains phosphoran olivine was found whose P contents are approaching the maximum P contents in olivine according to the experimental investigations of Boesenberg and Hewins (Geochim Cosmochim Acta 74:1923-1941, 2010). The textures within these domains indicate strongly disequilibrium conditions. The phosphoran olivines formed due to reactions involving apatite and the mineral assemblage of the quartzphyllites, and coexist with plagioclase and a tri-calcium phosphate phase (TCP) showing stanfieldite Ca4(Mg, Fe2+, Mn2+)5(PO4)6 composition. In terms of its chemical composition, olivine shows a wide range in composition with P ranging from 0.3 to 0.54 a.p.f.u, which corresponds to maximal 23 wt.% P2O5. These are the highest P-contents in olivine reported from rocks so far. The incorporation of P correlates with decreasing Si contents according to the charge balancing scheme 2{{P}^{5+ }}+□{{M}_{1,2 }}=2S{{i}^{4+ }}+{{( {Mg,Fe} )}^{2+ }}{{M}_{1,2 }} . Therefore P can only be incorporated in combination with a vacancy on the M1,2 position. Micro-Raman spectroscopy of phosphoran olivines indicates that these olivines can easily be identified with this method due to the strong signals of the SiO4 and PO4 vibrations. The external vibrations of the M1,2 sites at low wave-numbers are more complex than for P-free olivine. This might be due to the effect of P5+ on

Dynamic Solubility Limits in Nanosized Olivine LiFePO4

NARCIS (Netherlands)

Wagemaker, Marnix; Singh, Deepak P.; Borghols, Wouter J.H.; Lafont, Ugo; Haverkate, Lucas; Peterson, Vanessa K.; Mulder, Fokko M.

2011-01-01

Because of its stability, nanosized olivine LiFePO4 opens the door toward high-power Li-ion battery technology for large-scale applications as required for plug-in hybrid vehicles. Here, we reveal that the thermodynamics of first-order phase transitions in nanoinsertion materials is distinctly

Enhanced electrochemical performance of different morphological C/LiMnPO4 nanoparticles from hollow-sphere Li3PO4 precursor via a delicate polyol-assisted hydrothermal method

Science.gov (United States)

Cui, Yu-Ting; Xu, Ning; Kou, Li-Qin; Wu, Meng-Tao; Chen, Li

2014-03-01

With the hollow-sphere Li3PO4 as precursor, a delicate polyol-assisted hydrothermal method is devised to synthesize high-performance LiMnPO4. Orthorhombic shaped, irregular flaky shaped and sphere-like LiMnPO4 are sequentially prepared by decreasing the water-diethylene glycol (DEG) ratio. The capacity, cycling stability and rate performance of all samples prepared by the new synthesis method are improved significantly. And the C/LiMnPO4 with irregular flaky shape exhibits a capacity of 154.1 mA h g-1 at C/20, 147.4 mA h g-1 at C/10 and 102.5 mA h g-1 at 2 C, which is the best performance ever reported for LiMnPO4 active material with similar carbon additives.

Comparison of electrochemical performances of olivine NaFePO4 in sodium-ion batteries and olivine LiFePO4 in lithium-ion batteries.

Science.gov (United States)

Zhu, Yujie; Xu, Yunhua; Liu, Yihang; Luo, Chao; Wang, Chunsheng

2013-01-21

Carbon-coated olivine NaFePO(4) (C-NaFePO(4)) spherical particles with a uniform diameter of ∼80 nm are obtained by chemical delithiation and subsequent electrochemical sodiation of carbon-coated olivine LiFePO(4) (C-LiFePO(4)), which is synthesized by a solvothermal method. The C-NaFePO(4) electrodes are identical (particle size, particle size distribution, surface coating, and active material loading, etc.) to C-LiFePO(4) except that Li ions in C-LiFePO(4) are replaced by Na ions, making them ideal for comparison of thermodynamics and kinetics between C-NaFePO(4) cathode in sodium-ion (Na-ion) batteries and C-LiFePO(4) in lithium-ion (Li-ion) batteries. In this paper, the equilibrium potentials, reaction resistances, and diffusion coefficient of Na in C-NaFePO(4) are systematically investigated by using the galvanostatic intermittent titration technique (GITT), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and compared to those of the well-known LiFePO(4) cathodes in Li-ion batteries. Due to the lower diffusion coefficient of Na-ion and higher contact and charge transfer resistances in NaFePO(4) cathodes, the rate performance of C-NaFePO(4) in Na-ion batteries is much worse than that of C-LiFePO(4) in Li-ion batteries. However, the cycling stability of C-NaFePO(4) is almost comparable to C-LiFePO(4) by retaining 90% of its capacity even after 100 charge-discharge cycles at a charge-discharge rate of 0.1 C.

Characterization and petrologic interpretation of olivine-rich basalts at Gusev Crater, Mars

Science.gov (United States)

McSween, H.Y.; Wyatt, M.B.; Gellert, Ralf; Bell, J.F.; Morris, R.V.; Herkenhoff, K. E.; Crumpler, L.S.; Milam, K.A.; Stockstill, K.R.; Tornabene, L.L.; Arvidson, R. E.; Bartlett, P.; Blaney, D.; Cabrol, N.A.; Christensen, P.R.; Clark, B. C.; Crisp, J.A.; Des Marais, D.J.; Economou, T.; Farmer, J.D.; Farrand, W.; Ghosh, A.; Golombek, M.; Gorevan, S.; Greeley, R.; Hamilton, V.E.; Johnson, J. R.; Joliff, B.L.; Klingelhofer, G.; Knudson, A.T.; McLennan, S.; Ming, D.; Moersch, J.E.; Rieder, R.; Ruff, S.W.; Schrorder, C.; de Souza, P.A.; Squyres, S. W.; Wanke, H.; Wang, A.; Yen, A.; Zipfel, J.

2006-01-01

Rocks on the floor of Gusev crater are basalts of uniform composition and mineralogy. Olivine, the only mineral to have been identified or inferred from data by all instruments on the Spirit rover, is especially abundant in these rocks. These picritic basalts are similar in many respects to certain Martian meteorites (olivine-phyric shergottites). The olivine megacrysts in both have intermediate compositions, with modal abundances ranging up to 20-30%. Associated minerals in both include low-calcium and high-calcium pyroxenes, plagioclase of intermediate composition, iron-titanium-chromium oxides, and phosphate. These rocks also share minor element trends, reflected in their nickel-magnesium and chromium-magnesium ratios. Gusev basalts and shergottites appear to have formed from primitive magmas produced by melting an undepleted mantle at depth and erupted without significant fractionation. However, apparent differences between Gusev rocks and shergottites in their ages, plagioclase abundances, and volatile contents preclude direct correlation. Orbital determinations of global olivine distribution and compositions by thermal emission spectroscopy suggest that olivine-rich rocks may be widespread. Because weathering under acidic conditions preferentially attacks olivine and disguises such rocks beneath alteration rinds, picritic basalts formed from primitive magmas may even be a common component of the Martian crust formed during ancient and recent times. Copyright 2006 by the American Geophysical Union.

Formation of H2 and CH4 by weathering of olivine at temperatures between 30 and 70°C

Directory of Open Access Journals (Sweden)

Crill Patrick

2011-06-01

Full Text Available Abstract Hydrocarbons such as CH4 are known to be formed through the Fischer-Tropsch or Sabatier type reactions in hydrothermal systems usually at temperatures above 100°C. Weathering of olivine is sometimes suggested to account for abiotic formation of CH4 through its redox lowering and water splitting properties. Knowledge about the CH4 and H2 formation processes at low temperatures is important for the research about the origin and cause of early Earth and Martian CH4 and for CO2 sequestration. We have conducted a series of low temperature, long-term weathering experiments in which we have tested the CH4 and H2 formation potential of forsteritic olivine. The results show low temperature CH4 production that is probably influenced by chromite and magnetite as catalysts. Extensive analyses of a potential CH4 source trapped in the crystal structure of the olivine showed no signs of incorporated CH4. Also, the available sources of organic carbon were not enough to support the total amount of CH4 detected in our experiments. There was also a linear relationship between silica release into solution and the net CH4 accumulation into the incubation bottle headspaces suggesting that CH4 formation under these conditions could be a qualitative indicator of olivine dissolution. It is likely that minerals such as magnetite, chromite and other metal-rich minerals found on the olivine surface catalyze the formation of CH4, because of the low temperature of the system. This may expand the range of environments plausible for abiotic CH4 formation both on Earth and on other terrestrial bodies.

Novel lithium iron phosphate materials for lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Popovic, Jelena

2011-06-15

Conventional energy sources are diminishing and non-renewable, take million years to form and cause environmental degradation. In the 21st century, we have to aim at achieving sustainable, environmentally friendly and cheap energy supply by employing renewable energy technologies associated with portable energy storage devices. Lithium-ion batteries can repeatedly generate clean energy from stored materials and convert reversely electric into chemical energy. The performance of lithium-ion batteries depends intimately on the properties of their materials. Presently used battery electrodes are expensive to be produced; they offer limited energy storage possibility and are unsafe to be used in larger dimensions restraining the diversity of application, especially in hybrid electric vehicles (HEVs) and electric vehicles (EVs). This thesis presents a major progress in the development of LiFePO4 as a cathode material for lithium-ion batteries. Using simple procedure, a completely novel morphology has been synthesized (mesocrystals of LiFePO4) and excellent electrochemical behavior was recorded (nanostructured LiFePO4). The newly developed reactions for synthesis of LiFePO4 are single-step processes and are taking place in an autoclave at significantly lower temperature (200 deg. C) compared to the conventional solid-state method (multi-step and up to 800 deg. C). The use of inexpensive environmentally benign precursors offers a green manufacturing approach for a large scale production. These newly developed experimental procedures can also be extended to other phospho-olivine materials, such as LiCoPO4 and LiMnPO4. The material with the best electrochemical behavior (nanostructured LiFePO4 with carbon coating) was able to deliver a stable 94% of the theoretically known capacity.

Experimental measurements of 3He and 4He mobility in olivine and clinopyroxene at magmatic temperatures

Science.gov (United States)

Trull, T. W.; Kurz, M. D.

1993-03-01

In-vacuo heating of 0.5 -0.7 mm olivine and clinopyroxene grains separated from Hawaiian ultramafic xenoliths leads to complete He loss within hours to days for temperatures of 700-1400°C. Diffusivities calculated from the observed release rates assuming spherical grains and initially homogeneous He distributions define Arrhenius relations with activation energies of 420 ± 20 and 290 ± 40 Kj/mol and log 10D0 of +5.1 ± .7 and +2.1 ± 1.2 cm 2/s in olivine and pyroxene, respectively. Values at 1350°C are 5.3 × 10 -9 cm 2/s in olivine and 10 times faster in pyroxene (4.7 × 10 -8 cm 2/s). These values include small corrections for grain size variations and, in the case of olivine, about 15% prior diffusive He loss. However, an important factor that has not been considered in previous studies of this type, is that the xenolith He resides predominantly within CO 2 rich fluid inclusions. Theoretical description of He loss in such a case demonstrates that the diffusivities calculated using the standard approach actually represent the product of the true volume diffusivity ( D) and the helium solubility, as represented by the distribution coefficient KDv (defined by C crystal/C fluid). Although He solubility in crystals is not well determined, estimates based on the CO 2 concentrations in these samples suggest that it is very low ( KDv of 3 × 10 -4 for pyroxene and 6 × 10 -6 for olivine; which also implies low crystal-melt distribution coefficients of .05 and .001). The resultant corrected diffusion rates are significantly faster than those obtained by the standard approach (~ 10 -4 cm 2/s at 1350°C and are thus higher than basaltic melt values). The most reasonable interpretation of this result is that He release is enhanced by internal grain fractures, including the planar healed cracks along which most fluid inclusions are arrayed. This treatment illustrates the difficulties involved in extrapolating laboratory He release measurements to nature, in particular

Enhanced electrochemical performance of LiMn2O4 by constructing a stable Mn2+-rich interface

Science.gov (United States)

Lu, Zhongpei; Lu, Xiaojun; Ding, Jingjing; Zhou, Ting; Ge, Tao; Yang, Gang; Yin, Fan; Wu, Mingfang

2017-12-01

Spinel LiMn2O4 has drawn continuous attentions due to its low cost, good electrochemical performance, environmental friendliness and natural abundant resources. In view of its severe capacity fading, some types of manganese-based compounds with different Mn oxidation states are selected to protect bare LiMn2O4 by constructing a stable coating layer. In this work, LiMn2O4@LiMnPO4 composite, spherical LiMn2O4 (LMO) as core and Mn2+-rich phase of LiMnPO4 (LMP) as shell, is designed and synthesized. Two composites of LiMn2O4 particles coated with 3 wt% and 10 wt% LiMnPO4 have been compared studied. After 100 cycles at 0.5C rate, the two samples deliver capacity retentions of 96.63% and 93.23% of their initial capacities. Moreover, LMO coated by 3 wt% LiMnPO4 delivers 100.3 mAh g-1 after 200 cycles at 10C rate and 76.3 mAh g-1 after 1000 cycles at 20C rate, much higher than bare LiMn2O4 with 90 mAh g-1 and 45.8 mAh g-1, respectively. This core-shell structure with Mn2+-rich phase as a coating layer effectively enhance the material's cycling performance and rate capacity by reducing the contact of LiMn2O4 with electrolyte.

Cotectic proportions of olivine and spinel in olivine-tholeiitic basalt and evaluation of pre-eruptive processes

Science.gov (United States)

Roeder, Peter; Gofton, Emma; Thornber, Carl

2006-01-01

The volume %, distribution, texture and composition of coexisting olivine, Cr-spinel and glass has been determined in quenched lava samples from Hawaii, Iceland and mid-oceanic ridges. The volume ratio of olivine to spinel varies from 60 to 2800 and samples with >0·02% spinel have a volume ratio of olivine to spinel of approximately 100. A plot of wt % MgO vs ppm Cr for natural and experimental basaltic glasses suggests that the general trend of the glasses can be explained by the crystallization of a cotectic ratio of olivine to spinel of about 100. One group of samples has an olivine to spinel ratio of approximately 100, with skeletal olivine phenocrysts and small (within olivine phenocrysts is thought to be due to skeletal olivine phenocrysts coming into physical contact with spinel by synneusis during the chaotic conditions of ascent and extrusion. A second group of samples tend to have large olivine phenocrysts relatively free of included spinel, a few large (>100 μm) spinel crystals that show evidence of two stages of growth, and a volume ratio of olivine to spinel of 100 to well over 1000. The olivine and spinel in this group have crystallized more slowly with little physical interaction, and show evidence that they have accumulated in a magma chamber.

Fe2+-Mg2+ order in an olivine from the lunar anorthosite 67075 and the significance of cation order in lunar and terrestrial olivines

International Nuclear Information System (INIS)

Ghose, Subrata; Wan, Che'ng; McCallum, I.

1976-01-01

In an olivine, (Fesub(1.010)Mgsub(1.015)Casub(0.002)Mnsub(0.014)SiO 4 , from the lunar anorthosite 67075, Fe 2+ indicates a slight preference for the M1 site, the KD value being 1.197. Available data in synthetic, lunar and terrestrial olivines indicate that for iron-rich olivines (>20 mol percent Fayalite), Fe 2+ prefers the M1 site, the site preference decreasing with decreasing temperature. In magnesium-rich olivines, Fe 2+ prefers the M1 site at high temperature, but may prefer the M2 site at low temperature. The olivine from sample 67075 most likely was cooled from the crystallization temperature to 800 0 C or less in 10 days. (author)

Synthesis of nanometer-sized fayalite and magnesium-iron(II) mixture olivines

Energy Technology Data Exchange (ETDEWEB)

Qafoku, Odeta; Ilton, Eugene S.; Bowden, Mark E.; Kovarik, Libor; Zhang, Xin; Kukkadapu, Ravi K.; Engelhard, Mark H.; Thompson, Christopher J.; Schaef, Herbert T.; McGrail, Bernard Peter; Rosso, Kevin M.; Loring, John S.

2018-04-01

Olivines are divalent orthosilicates with important geologic, biological, and industrial significance and are typically comprised of mixtures of Mg2+ and Fe2+ ranging from forsterite (Mg2SiO4) to fayalite (Fe2SiO4). Investigating the role of Fe(II) in olivine reactivity requires the ability to synthesize olivines that are nanometer-sized, have different percentages of Mg2+ and Fe2+, and have good bulk and surface purity. This article demonstrates a new method for synthesizing nanosized fayalite and Mg-Fe mixture olivines. First, carbonaceous precursors are generated from sucrose, PVA, colloidal silica, Mg2+, and Fe3+. Second, these precursors are calcined in air to burn carbon and create mixtures of Fe(III)-oxides, forsterite, and SiO2. Finally, calcination in reducing CO-CO2 gas buffer leads to Fe(II)-rich olivines. XRD, Mössbauer, and IR analyses verify good bulk purity and composition. XPS indicates that surface iron is in its reduced Fe(II) form, and surface Si is consistent with olivine. SEM shows particle sizes predominately between 50 and 450 nm, and BET surface areas are 2.8-4.2 m2/g. STEM HAADF analysis demonstrates even distributions of Mg and Fe among the available M1 and M2 sites of the olivine crystals. These nanosized Fe(II)-rich olivines are suitable for laboratory studies with in situ probes that require mineral samples with high reactivity at short timescales.

Olivine-Based Blended Compounds as Positive Electrodes for Lithium Batteries

Directory of Open Access Journals (Sweden)

Christian M. Julien

2016-05-01

Full Text Available Blended cathode materials made by mixing LiFePO4 (LFP with LiMnPO4 (LMP or LiNi1/3Mn1/3Co1/3O2 (NMC that exhibit either high specific energy and high rate capability were investigated. The layered blend LMP–LFP and the physically mixed blend NMC–LFP are evaluated in terms of particle morphology and electrochemical performance. Results indicate that the LMP–LFP (66:33 blend has a better discharge rate than the LiMn1−yFeyPO4 with the same composition (y = 0.33, and NMC–LFP (70:30 delivers a remarkable stable capacity over 125 cycles. Finally, in situ voltage measurement methods were applied for the evaluation of the phase evolution of blended cathodes and gradual changes in cell behavior upon cycling. We also discuss through these examples the promising development of blends as future electrodes for new generations of Li-ion batteries.

The P3 kimberlite and P4 lamproite, Wajrakarur kimberlite field, India: mineralogy, and major and minor element compositions of olivines as records of their phenocrystic vs xenocrystic origin

Science.gov (United States)

Shaikh, Azhar M.; Kumar, Satya P.; Patel, Suresh C.; Thakur, Satyajeet S.; Ravi, Subramanian; Behera, Duryadhan

2018-03-01

Distinctly different groundmass mineralogy characterise the hypabyssal facies, Mesoproterozoic diamondiferous P3 and P4 intrusions from the Wajrakarur Kimberlite Field, southern India. P3 is an archetypal kimberlite with macrocrysts of olivine and phlogopite set in a groundmass dominated by phlogopite and monticellite with subordinate amounts of serpentine, spinel, perovskite, apatite, calcite and rare baddeleyite. P4 contains mega- and macrocrysts of olivine set in a groundmass dominated by clinopyroxene and phlogopite with subordinate amounts of serpentine, spinel, perovskite, apatite, and occasional gittinsite, and is mineralogically interpreted as an olivine lamproite. Three distinct populations of olivine, phlogopite and clinopyroxene are recognized based on their microtextural and compositional characteristics. The first population includes glimmerite and phlogopite-clinopyroxene nodules, and Mg-rich olivine macrocrysts (Fo 90-93) which are interpreted to be derived from disaggregated mantle xenoliths. The second population comprises macrocrysts of phlogopite and Fe-rich olivine (Fo 81-89) from P3, megacrysts and macrocrysts of Fe-rich olivine (Fo 85-87) from P4 and a rare olivine-clinopyroxene nodule from P4 which are suggested to have a genetic link with the precursor melt of the respective intrusions. The third population represents clearly magmatic minerals such as euhedral phenocrysts of Fe-rich olivine (Fo 85-90) crystallised at mantle depths, and olivine overgrowth rims formed contemporaneously with groundmass minerals at crustal levels. Close spatial association and contemporaneous emplacement of P3 kimberlite and P4 lamproite is explained by a unifying petrogenetic model which involves the interaction of a silica-poor carbonatite melt with differently metasomatised wall rocks in the lithospheric mantle. It is proposed that the metasomatised wall rock for lamproite contained abundant MARID-type and phlogopite-rich metasomatic veins, while that for

Characterization and luminescent properties of thermally annealed olivines

International Nuclear Information System (INIS)

Colin-Garcia, Maria; Correcher, Virgilio; Garcia-Guinea, Javier; Heredia-Barbero, Alejandro; Roman-Lopez, Jesus; Ortega-Gutierrez, Fernando; Negron-Mendoza, Alicia; Ramos-Bernal, Sergio

2013-01-01

Olivine is an iron-magnesium solid solution silicate (Mg,Fe) 2 SiO 4 and it is probably one of the most abundant mineral phase in the Solar System, it is present in the primitive carbonaceous meteorites (i.e Allende), and in ordinary chondritic meteorite, comets or terrestrial planets. The olivine grains in those bodies have been exposed to different radiation sources like UV, electrons, cosmic radiation, etc. Here, we explore the effect of ionizing and non ionizing radiation on the luminescence emission of the two well-characterised olivine samples from Mexico and Spain by means of cathodoluminescence and thermoluminescence. The analyses by X-ray dispersive energies in the scanning electron microscopy show differences between the samples in the amount of iron and magnesium and also show traces of rare elements. Olivine exhibits spectral cathodoluminescence emissions of low intensity, explained for the quenching of the luminescence of the iron, and sharp signals assigned as impurities. Cathodoluminescence and thermoluminescence glow curves of the natural, and UV induced olivine samples were obtained. Our results show that thermal treatments at 1100 °C change the mineral molecular structure and the luminescence properties of this mineral phase. These results confirm an active participation of physical factors influencing the luminescent properties of olivine. -- Highlights: ► Luminescent properties of two olivines samples (Mexican and Spanish) were explored. ► EDS show different iron and magnesium content and traces of rare elements on both. ► Olivine exhibits spectral CL emissions of low intensity due to the quenching of iron. ► Treatments at 1100 °C change the mineral structure and its response to UV radiation

Magnetism in olivine-type LiCo(1-x)Fe(x)PO4 cathode materials: bridging theory and experiment.

Science.gov (United States)

Singh, Vijay; Gershinsky, Yelena; Kosa, Monica; Dixit, Mudit; Zitoun, David; Major, Dan Thomas

2015-12-14

In the current paper, we present a non-aqueous sol-gel synthesis of olivine type LiCo1-xFexPO4 compounds (x = 0.00, 0.25, 0.50, 0.75, 1.00). The magnetic properties of the olivines are measured experimentally and calculated using first-principles theory. Specifically, the electronic and magnetic properties are studied in detail with standard density functional theory (DFT), as well as by including spin-orbit coupling (SOC), which couples the spin to the crystal structure. We find that the Co(2+) ions exhibit strong orbital moment in the pure LiCoPO4 system, which is partially quenched upon substitution of Co(2+) by Fe(2+). Interestingly, we also observe a non-negligible orbital moment on the Fe(2+) ion. We underscore that the inclusion of SOC in the calculations is essential to obtain qualitative agreement with the observed effective magnetic moments. Additionally, Wannier functions were used to understand the experimentally observed rising trend in the Néel temperature, which is directly related to the magnetic exchange interaction paths in the materials. We suggest that out of layer M-O-P-O-M magnetic interactions (J⊥) are present in the studied materials. The current findings shed light on important differences observed in the electrochemistry of the cathode material LiCoPO4 compared to the already mature olivine material LiFePO4.

Extraction of in situ cosmogenic 14C from olivine

Science.gov (United States)

Pigati, J.S.; Lifton, N.A.; Timothy, Jull A.J.; Quade, Jay

2010-01-01

Chemical pretreatment and extraction techniques have been developed previously to extract in situ cosmogenic radiocarbon (in situ 14C) from quartz and carbonate. These minerals can be found in most environments on Earth, but are usually absent from mafic terrains. To fill this gap, we conducted numerous experiments aimed at extracting in situ 14C from olivine ((Fe,Mg)2SiO4). We were able to extract a stable and reproducible in situ 14C component from olivine using stepped heating and a lithium metaborate (LiBO2) flux, following treatment with dilute HNO3 over a variety of experimental conditions. However, measured concentrations for samples from the Tabernacle Hill basalt flow (17.3 ?? 0.3 ka4) in central Utah and the McCarty's basalt flow (3.0 ?? 0.2 ka) in western New Mexico were significantly lower than expected based on exposure of olivine in our samples to cosmic rays at each site. The source of the discrepancy is not clear. We speculate that in situ 14C atoms may not have been released from Mg-rich crystal lattices (the olivine composition at both sites was ~Fo65Fa35). Alternatively, a portion of the 14C atoms released from the olivine grains may have become trapped in synthetic spinel-like minerals that were created in the olivine-flux mixture during the extraction process, or were simply retained in the mixture itself. Regardless, the magnitude of the discrepancy appears to be inversely proportional to the Fe/(Fe+Mg) ratio of the olivine separates. If we apply a simple correction factor based on the chemical composition of the separates, then corrected in situ 14C concentrations are similar to theoretical values at both sites. At this time, we do not know if this agreement is fortuitous or real. Future research should include measurement of in situ 14C concentrations in olivine from known-age basalt flows with different chemical compositions (i.e. more Fe-rich) to determine if this correction is robust for all olivine-bearing rocks. ?? 2010 by the Arizona

Evaluation of olivine refractories for TES

Science.gov (United States)

Gay, B. M.; Cochrane, R. L.; Palmour, H., III; Paisley, M. J.

1982-02-01

The principal objectives of this program are to (1) experimentally determine the degree of improvement in thermal and mechanical performance that can be obtained with an olivine thermal storage brick made of domestic materials using advanced processing techniques compared with state-of-the-art as represented by commercial European bricks, (2) conduct an assessment of existing German ceramic process technology and determine its adaptability to domestic raw materials and manufacturing practices, and (3) investigate, on a limited basis, method for further improvement of domestic-olivine brick. To date, accomplishments include (1) installation of improved, computer-based instrumentation, (2) the use of this system to determine performance characteristics of a set of heat storage refractories under cyclic use conditions, (3) acquisition of the services of a knowledgeable European consultant, (4) continued lab-scale process/property optimization studies, and (5) comparative testing of olivine-based and magnesite-based heat storage refractories in the calorimetric test facility at Purdue University.

[Phosphate solubilization of Aureobasidium pullulan F4 and its mechanism].

Science.gov (United States)

Wang, Dan; Zhan, Jing; Sun, Qing-Ye

2014-07-01

The Aureobasidium pullulans F4 was isolated from the rhizosphere of Hippochaete ramosissimum in Tongguanshan mine wasteland in Tongling City, Anhui Province. Liquid culture was conducted with four kinds of phosphorus sources, calcium phosphate, aluminum phosphate, ferric phosphate and rock phosphate to determine the pH, dissolved phosphorus, phosphorus in the bacteria and organic acid in the solution. The results showed that the phosphate solubilization by A. pullulans F4 varied with phosphorus sources, which decreased in order of aluminum phosphate > ferric phosphate, calcium phosphate > rock phosphate. The amounts of dissolved phosphorus in the different treatments were all higher than 200 mg x L(-1). The pH of the medium dropped immediately in 48 h, and the aluminum phosphate and ferric phosphate treatments showed a greater decrease in pH than the calcium phosphate and rock phosphate treatments. The organic acid synthesized by A. pullulans F4 included oxalic acid, citric acid and tartaric acid, and oxalic acid, among which oxalic acid was the dominated component. The phosphate dissolving capacity of A. pullulans F4 showed no significant correlation with organic acid, but significantly correlated with the pH. The available phosphorus was significantly improved with the combined application of A. pullulans F4 and glucose, suggesting A. pullulans F4 was a potent candidate for remediation of copper mine wastelands.

Arsenic Sorption on Mechanically Activated Magnetite and Olivine

Directory of Open Access Journals (Sweden)

Zdenka Bujňáková

2012-12-01

Full Text Available Arsenic sorption on mechanically activated minerals such as magnetite Fe3O4 (Kiruna, Sweden and olivine (Mg,Fe2SiO4 (Ǻheim,Norway has been studied and compared in this work. Experiments were carried out with non-activated and mechanically activatedsamples. The activation of both minerals was performed in a planetary mill at different milling conditions. The specific surface areaand consequent sorption activity were enhanced by mechanical activation. The using of olivine seems to be better than magnetite fromthe point of view of milling time, which is necessary for achievement of the same sorption effect.

Emulsion drying synthesis of olivine LiFePO4/C composite and its electrochemical properties as lithium intercalation material

International Nuclear Information System (INIS)

Myung, Seung-Taek; Komaba, Shinichi; Hirosaki, Norimitsu; Yashiro, Hitoshi; Kumagai, Naoaki

2004-01-01

The electroactive LiFePO 4 /C nano-composite has been synthesized by an emulsion drying method. During burning-out the oily emulsion precipitates in an air-limited atmosphere at 300 deg. C, amorphous or low crystalline carbon was generated along with releasing carbon oxide gases, and trivalent iron as a cheap starting material was immediately reduced to the divalent one at this stage as confirmed by X-ray photoelectron spectroscopy, leading to a low crystalline LiFePO 4 /C composite. Heat-treatment of the low crystalline LiFePO 4 /C in an Ar atmosphere resulted in a well-ordered olivine structure, as refined by Rietveld refinement of the X-ray diffraction pattern. From secondary electron microscopic and scanning transmission electron microscopic observations with the corresponding elemental mapping images of iron and phosphorous, it was found that the LiFePO 4 powders are modified by fine carbon. The in situ formation of the nano-sized carbon during crystallization of LiFePO 4 brought about two advantages: (i) an optimized particle size of LiFePO 4 , and (ii) a uniform distribution of fine carbon in the product. These effects of the fine carbon on LiFePO 4 /C composite led to high capacity retention upon cycling at 25 and 50 deg. C and high rate capability, resulting from a great enhancement of electric conductivity as high as 10 -4 S cm -1 . That is, the obtained capacity was higher than 90 mAh (g-phosphate) -1 by applying a higher current density of about 1000 mA g -1 (11 C) at 50 deg. C

Natural fumarolic alteration of fluorapatite, olivine, and basaltic glass, and implications for habitable environments on Mars.

Science.gov (United States)

Hausrath, Elisabeth M; Tschauner, Oliver

2013-11-01

Fumaroles represent a very important potential habitat on Mars because they contain water and nutrients. Global deposition of volcanic sulfate aerosols may also have been an important soil-forming process affecting large areas of Mars. Here we identify alteration from the Senator fumarole, northwest Nevada, USA, and in low-temperature environments near the fumarole to help interpret fumarolic and acid vapor alteration of rocks and soils on Mars. We analyzed soil samples and fluorapatite, olivine, and basaltic glass placed at and near the fumarole in in situ mineral alteration experiments designed to measure weathering under natural field conditions. Using synchrotron X-ray diffraction, we clearly observe hydroxyl-carbonate-bearing fluorapatite as a fumarolic alteration product of the original material, fluorapatite. The composition of apatites as well as secondary phosphates has been previously used to infer magmatic conditions as well as fumarolic conditions on Mars. To our knowledge, the observations reported here represent the first documented instance of formation of hydroxyl-carbonate-bearing apatite from fluorapatite in a field experiment. Retreat of olivine surfaces, as well as abundant NH4-containing minerals, was also characteristic of fumarolic alteration. In contrast, alteration in the nearby low-temperature environment resulted in formation of large pits on olivine surfaces, which were clearly distinguishable from the fumarolic alteration. Raman signatures of some fumarolically impacted surfaces are consistent with detection of the biological molecules chlorophyll and scytenomin, potentially useful biosignatures. Observations of altered minerals on Mars may therefore help identify the environment of formation and understand the aqueous history and potential habitability of that planet.

Experimental constraints on partitioning and zoning of phosphorus in igneous olivine

Science.gov (United States)

Ersoy, Ö.; Nikogosian, I.; Mason, P. R. D.; Van Westrenen, W.; van Bergen, M.

2017-12-01

Fast diffusion and homogenization of divalent cations hamper the preservation of original chemical compositions and zoning patterns of igneous olivine phenocrysts. Sluggish intracrystalline diffusion of phosphorus in igneous olivine on the other hand allows the complex zoning patterns to be retained, making it a crucial element for reconstruction of cooling histories and evolution of the host magma. Crystallization rate variations, diffusion controlled growth or compositional controls on melt-mineral partitioning have been put forward as mechanisms controlling zoning of igneous olivine in phosphorus. Here, we investigate partitioning and zoning of phosphorus in igneous olivines by a comparison of natural and experimentally grown olivines. We explore the importance of variable degrees of undercooling and cooling rates in crystallizing melt (M1) with a starting composition equivalent to that of an Italian high-potassium basalt (Tliq=1274 °C). We examine the extent of compositional control on partitioning by varying the amount of alkali enrichment in starting compositions that are otherwise equivalent to melt M1. Olivine crystallization experiments were conducted in rhenium capsules suspended in a vertical 1-atm gas-mixing furnace at Vrije Universiteit Amsterdam (VUA) with fO2 buffered at 1.4 to 1.7 log units below the Ni-NiO buffer. Sets of dynamic crystallization experiments with various degrees of undercooling and controlled cooling rate experiments with varying cooling rates were performed. We compare the results with our extensive EPMA and LA-ICPMS dataset on olivines from Italian K-rich mafic lavas and olivine hosted primitive melt inclusions (MIs). Phosphorus concentrations in the natural olivines reach 435 ppm P and MIs contain up to 2.2 wt.% P2O5. High resolution (1-4 µm per pixel) element maps show both fine oscillatory, patchy and large scale sector zoning in P, uncorrelated with zoning in any other element. The MIs are almost always found in P-poor zones

Thermal equation of state of (Mg 0.9Fe 0.1) 2SiO 4 olivine

Science.gov (United States)

Liu, Wei; Li, Baosheng

2006-08-01

In situ synchrotron X-ray diffraction measurements have been carried out on San Carlos olivine (Mg 0.9Fe 0.1) 2SiO 4 up to 8 GPa and 1073 K. Data analysis using the high-temperature Birch-Murnaghan (HTBM) equation of state (EoS) yields the temperature derivative of the bulk modulus (∂ KT/∂ T) P = -0.019 ± 0.002 GPa K -1. The thermal pressure (TH) approach gives αKT = 4.08 ± 0.10 × 10 -3 GPa K -1, from which (∂ KT/∂ T) P = -0.019 ± 0.001 GPa K -1 is derived. Fitting the present data to the Mie-Grüneisen-Debye (MGD) formalism, the Grüneisen parameter at ambient conditions γ0 is constrained to be 1.14 ± 0.02 with fixed volume dependence q = 1. Combining the present data with previous results on iron-bearing olivine and fitting to MGD EoS, we obtain γ0 = 1.11 ± 0.01 and q = 0.54 ± 0.36. In this study the thermoelastic parameters obtained from various approaches are in good agreement with one another and previous results.

GATA4-mediated cardiac hypertrophy induced by D-myo-inositol 1,4,5-tris-phosphate

International Nuclear Information System (INIS)

Zhu Zhiming; Zhu Shanjun; Liu Daoyan; Yu Zengping; Yang Yongjian; Giet, Markus van der; Tepel, Martin

2005-01-01

We evaluated the effects of D-myo-inositol 1,4,5-tris-phosphate on cardiac hypertrophy. D-myo-inositol 1,4,5-tris-phosphate augmented cardiac hypertrophy as evidenced by its effects on DNA synthesis, protein synthesis, and expression of immediate-early genes c-myc and c-fos, β-myosin heavy chain, and α-actin. The administration of D-myo-inositol 1,4,5-tris-phosphate increased the expression of nuclear factor of activated T-cells and cardiac-restricted zinc finger transcription factor (GATA4). Real-time quantitative RT-PCR showed that D-myo-inositol 1,4,5-tris-phosphate-induced GATA4 mRNA was significantly enhanced even in the presence of the calcineurin inhibitor, cyclosporine A. The effect of D-myo-inositol 1,4,5-tris-phosphate was blocked after inhibition of inositol-trisphosphate receptors but not after inhibition of c-Raf/mitogen-activated protein kinase kinase (MEK)/mitogen-activated protein kinase (ERK) or p38 mitogen-activated protein kinase pathways. The study shows that D-myo-inositol 1,4,5-tris-phosphate-induced cardiac hypertrophy is mediated by GATA4 but independent from the calcineurin pathway

NiO and Fe/Mn in Fo-rich olivines from OIB, MORB, and mantle peridotites

Science.gov (United States)

Li, H.; Baker, M.; Hofmann, A. E.; Clague, D.; Stolper, E.

2006-12-01

Olivines from mantle peridotites have a narrow range of NiO (0.36±0.03 [1σ] wt%), but NiO of olivines in basalts suggest NiO in mantle olivines is actually more variable: e.g., Hawaiian phenocrysts (Fo>90) have NiO >0.55%, and olivines from continental flood basalts can have >0.5% NiO. At the other end of the spectrum, some basaltic suites (e.g., Iceland, MORBs) have Fo>90 olivines with NiO >0.2%. Partial melting calculations on peridotites show it is difficult to generate liquids that crystallize Fo>90 olivines with >0.4% NiO without resorting to complex processes. Hypotheses to explain the variability of NiO in mantle-derived olivines include (1) reaction of peridotite with silica-rich melts of eclogite results in decreasing modal abundance of olivine and increasing NiO in olivine [1,2]; (2) magmas with NiO-rich olivines come from sources enriched in NiO due to a core-derived component [3]. [4] proposed that high Fe/Mn of Hawaiian vs. Icelandic and MORB lavas reflect a core-derived component in their sources. Possible core incorporation is poorly constrained but FeO and NiO are expected to increase by such processes, leading to correlations between NiO and Fe/Mn in mantle rocks with significant core-derived components. We present high-precision analyses of Fo-rich olivines from OIBs, MORBs, komatiites, and mantle peridotites, focusing on NiO contents and Fe/Mn ratios. Our goal is to test hypotheses to explain elevated NiO of Fo-rich olivines in basalts. Olivines are Fo85.1-93.4; more were analyzed, but we focused on this range to avoid complications due to decreasing NiO in olivine with crystallization. Errors (1σ) are 0.01 wt% in NiO and 1.5 in Fe/Mn (wt). Our data show several features: (1) NiO contents and Fe/Mn ratios of Fo>88 olivines are positively correlated, with the low end of the trend (NiO ~0.23%, Fe/Mn ~61) defined by MORB and Iceland and the high end of the trend (NiO ~0.55%, Fe/Mn ~80) by Reunion and Hawaii. Between these end points, there is a

Texture and Elastic Anisotropy of Mantle Olivine

Science.gov (United States)

Nikitin, A. N.; Ivankina, T. I.; Bourilitchev, D. E.; Klima, K.; Locajicek, T.; Pros, Z.

Eight olivine rock samples from different European regions were collected for neu- tron texture analyses and for P-wave velocity measurements by means of ultrasonic sounding at various confining pressures. The orientation distribution functions (ODFs) of olivine were determined and pole figures of the main crystallographic planes were calculated. The spatial P-wave velocity distributions were determined at confining pressures from 0.1 to 400 MPa and modelled from the olivine textures. In dependence upon the type of rock (xenolith or dunite) different behavior of both the P-wave veloc- ity distributions and the anisotropy coefficients with various confining pressures was observed. In order to explain the interdependence of elastic anisotropy and hydrostatic pressure, a model for polycrystalline olivine rocks was suggested, which considers the influence of the crystallographic and the mechanical textures on the elastic behaviour of the polycrystal. Since the olivine texture depends upon the active slip systems and the deformation temperature, neutron texture analyses enable us to estimate depth and thermodynamical conditions during texture formation.

Change in Frictional Behavior during Olivine Serpentinization

Science.gov (United States)

Xing, T.; Zhu, W.; French, M. E.; Belzer, B.

2017-12-01

Hydration of mantle peridotites (serpentinization) is pervasive at plate boundaries. It is widely accepted that serpentinization is intrinsically linked to hydromechanical processes within the sub-seafloor, where the interplay between cracking, fluid supply and chemical reactions is responsible for a spectrum of fault slip, from earthquake swarms at the transform faults, to slow slip events at the subduction zone. Previous studies demonstrate that serpentine minerals can either promote slip or creep depend on many factors that include sliding velocity, temperature, pressure, interstitial fluids, etc. One missing link from the experimental investigation of serpentine to observations of tectonic faults is the extent of alteration necessary for changing the frictional behaviors. We quantify changes in frictional behavior due to serpentinization by conducting experiments after in-situ serpentinization of olivine gouge. In the sample configuration a layer of powder is sandwiched between porous sandstone blocks with 35° saw-cut surface. The starting material of fine-grained (63 120 µm) olivine powder is reacted with deionized water for 72 hours at 150°C before loading starts. Under the conventional triaxial configuration, the sample is stressed until sliding occurs within the gouge. A series of velocity-steps is then performed to measure the response of friction coefficient to variations of sliding velocity from which the rate-and-state parameters are deduced. For comparison, we measured the frictional behavior of unaltered olivine and pure serpentine gouges.Our results confirm that serpentinization causes reduced frictional strength and velocity weakening. In unaltered olivine gouge, an increase in frictional resistance with increasing sliding velocity is observed, whereas the serpentinized olivine and serpentine gouges favor velocity weakening behaviors at the same conditions. Furthermore, we observed that high pore pressures cause velocity weakening in olivine but

Mineral magnetism of dusty olivine

DEFF Research Database (Denmark)

Lappe, Sophie-Charlotte L. L.; Church, Nathan S.; Kasama, Takeshi

2011-01-01

The magnetic properties of olivine-hosted Fe-Ni particles have been studied to assess the potential of "dusty olivine" to retain a pre-accretionary remanence in chondritic meteorites. Both body-centered (bcc) and face-centered cubic (fcc) Fe-Ni phases were formed by reduction of a terrestrial...... olivine precursor. The presence of Ni complicates the magnetic properties during heating and cooling due to the fcc-bcc martensitic transition. First-order reversal curve (FORC) diagrams contain a central ridge with a broad coercivity distribution extending to 600 mT, attributed to non-interacting single......-domain (SD) particles, and a "butterfly" structure extending to 250 mT, attributed to single-vortex (SV) states. SD and SV states were imaged directly using electron holography. The location of the SD/SV boundary is broadly consistent with theoretical predictions. A method to measure the volume of individual...

Olivine-type cathode for rechargeable batteries: Role of chelating agents

International Nuclear Information System (INIS)

Kandhasamy, Sathiyaraj; Singh, Pritam; Thurgate, Stephen; Ionescu, Mihail; Appadoo, Dominique; Minakshi, Manickam

2012-01-01

Highlights: ► Olivine powder was synthesized by sol–gel method using a range of chelating agents. ► Role of chelating agents in olivine cathode was investigated for battery application. ► Battery was fabricated with olivine cathode, Zn anode and aqueous electrolyte. ► Synergetic effect of additives (CA + TEA + PVP) led to improved storage capacity. - Abstract: Olivine (LiCo 1/3 Mn 1/3 Ni 1/3 PO 4 ) powders were synthesized at 550–600 °C for 6 h in air by a sol–gel method using multiple chelating agents and used as a cathode material for rechargeable batteries. Range of chelating agents like a weak organic acid (citric acid – CA), emulsifier (triethanolamine – TEA) and non-ionic surfactant (polyvinylpyrrolidone – PVP) in sol–gel wet chemical synthesis were used. The dependence of the physicochemical properties of the olivine powders such as particle size, morphology, structural bonding and crystallinity on the chelating agent was extensively investigated. Among the chelating agents used, unique cycling behavior (75 mAh/g after 25 cycles) is observed for the PVP assisted olivine. This is due to volumetric change in trapped organic layer for first few cycles. The trapped organic species in the electrode–electrolyte interface enhances the rate of lithium ion diffusion with better capacity retention. In contrast, CA and TEA showed a gradual capacity fade of 30 and 38 mAh/g respectively after multiple cycles. The combination of all the three mixed chelating agents showed an excellent electrochemical behavior of 100 mAh/g after multiple cycles and the synergistic effect of these agents are discussed.

Evidence for a pressure-induced spin transition in olivine-type LiFePO4 triphylite

Science.gov (United States)

Núñez Valdez, Maribel; Efthimiopoulos, Ilias; Taran, Michail; Müller, Jan; Bykova, Elena; McCammon, Catherine; Koch-Müller, Monika; Wilke, Max

2018-05-01

We present a combination of first-principles and experimental results regarding the structural and magnetic properties of olivine-type LiFePO4 under pressure. Our investigations indicate that the starting P b n m phase of LiFePO4 persists up to 70 GPa. Further compression leads to an isostructural transition in the pressure range of 70-75 GPa, inconsistent with a former theoretical study. Considering our first-principles prediction for a high-spin to low-spin transition of Fe2 + close to 72 GPa, we attribute the experimentally observed isostructural transition to a change in the spin state of Fe2 + in LiFePO4. Compared to relevant Fe-bearing minerals, LiFePO4 exhibits the largest onset pressure for a pressure-induced spin state transition.

Moessbauer spectra of olivine-rich achondrites - Evidence for preterrestrial redox reactions

Science.gov (United States)

Burns, R. G.; Martinez, S. L.

1991-01-01

Moessbauer spectral measurements at 4.2 K were made on several ureilites and the two shergottites found in Antarctica, as well as two ureilite falls, three SNC meteorite falls, and two finds in order to distinguish products of preterrestrial redox reactions from phases formed during oxidative weathering on the earth. The spectra indicated that several ureilites contain major proportions of metallic iron, much of which resulted from preterrestrial carbon-induced reduction of ferrous iron in the outermost 10-100 microns of olivine grains in contact with carbonaceous material in the ureilites. The cryptocrystalline nature of these Fe inclusions in olivine renders the metal extremely vulnerable to aerial oxidation, even in ureilites collected as falls. It is inferred that the nanophase ferric oxides or oxyhydroxides identified in Brachina and Lafayette were produced by terrestrial weather of olivines before the meteorites were found. The absence of goethite in two olivine-bearing Antarctic shergottites suggests that the 2 percent ferric iron determined in their Moessbauer spectra also originated from oxidation on Mars.

Grafted NiO on natural olivine for dry reforming of methane

Directory of Open Access Journals (Sweden)

Grafted NiO on natural olivine for dry reforming of methane C Courson, L Udron, C Petit and A Kiennemann Sci. Technol. Adv. Mater. 3 No 3 (June 2002 271-282 Abstract | References Full text: Acrobat PDF (1.10 MB

2002-01-01

Full Text Available Natural olivine is used for gasification of biomass in a fluidised bed. Characterisations by X-ray diffraction and electron microscopies (SEM and TEM have proved the presence of a (Mg,Fe2SiO4 structure (Mg/Fe ratio: 9/1 with a rather broad distribution in elemental composition. Temperature programmed reduction has revealed equally the presence of iron oxides outside of this structure. The nature of free iron oxides can be both modified by increasing the temperature of calcination and confirmed by measurements of magnetism.The introduction of nickel oxide upon natural olivine is obtained by impregnation with a nitrate salt. The type of interaction of nickel oxide with olivine is different depending upon the preparation method and the calcination temperature. For calcination at 1100 °C, the effects of the amount of NiO and the number of impregnation have been studied. At a high temperature of calcination (1400 °C, NiO is integrated into the olivine structure and the amount of free iron increases. Integrated NiO on olivine is non-reducible, resulting in an inactive catalyst. At lower calcination temperatures grafted NiO is formed, a species which is reduced under catalytic test conditions without aggregation of particles. A single impregnation of nickel (5.5 wt% of NiO gives a stable catalyst activated directly under reaction conditions (CH4+CO2 yielding 96% CO and 76% H2. Catalysts with lower amounts of NiO or a double impregnation of nickel salt lead to a less stable system.Analysis reveals that no change in olivine structure nor size of nickel deposit occurs under test conditions. Equally there are no carbon deposits formed on these catalysts. A model of the evolution of each catalytic system arising from the different preparation methods is proposed. The observed deactivation of such catalysts is attributed to the increase in the amount of free iron, which favours the oxidative properties of the catalytic system.

Olivine-rich asteroids in the near-Earth space

Science.gov (United States)

Popescu, Marcel; Perna, D.; Barucci, M. A.; Fornasier, S.; Doressoundiram, A.; Lantz, C.; Merlin, F.; Belskaya, I. N.; Fulchignoni, M.

2018-06-01

In the framework of a 30-night spectroscopic survey of small near-Earth asteroids (NEAs), we present new results regarding the identification of olivine-rich objects. The following NEAs were classified as A-type using visible spectra obtained with 3.6-m New Technology Telescope: (293726) 2007 RQ17, (444584) 2006 UK, 2012 NP, 2014 YS34, 2015 HB117, 2015 LH, 2015 TB179, 2015 TW144. We determined a relative abundance of 5.4 per cent (8 out of 147 observed targets) A-types at a 100-m size range of NEA population. The ratio is at least five times larger compared with the previously known A-types, which represent less than ˜ 1 per cent of NEAs taxonomically classified. By taking into account that part of our targets may not be confirmed as olivine-rich asteroids by their near-infrared spectra, or they can have a nebular origin, our result provides an upper-limit estimation of mantle fragments at size ranges below 300 m. Our findings are compared with the `battered-to-bits' scenario, claiming that at small sizes the olivine-rich objects should be more abundant when compared with basaltic and iron ones.

Olivine-rich asteroids in the near-Earth space

Science.gov (United States)

Popescu, Marcel; Perna, D.; Barucci, M. A.; Fornasier, S.; Doressoundiram, A.; Lantz, C.; Merlin, F.; Belskaya, I. N.; Fulchignoni, M.

2018-03-01

In the framework of a 30-night spectroscopic survey of small near-Earth asteroids (NEAs) we present new results regarding the identification of olivine-rich objects. The following NEAs were classified as A-type using visible spectra obtained with 3.6 m NTT telescope: (293726) 2007 RQ17, (444584) 2006 UK, 2012 NP, 2014 YS34, 2015 HB117, 2015 LH, 2015 TB179, 2015 TW144. We determined a relative abundance of 5.4% (8 out of 147 observed targets) A-types at hundred meter size range of NEAs population. The ratio is at least five times larger compared with the previously known A-types, which represent less than ˜1% of NEAs taxonomically classified. By taking into account that part of our targets may not be confirmed as olivine-rich asteroids by their near-infrared spectra, or they can have a nebular origin, our result provides an upper-limit estimation of mantle fragments at size ranges bellow 300m. Our findings are compared with the "battered-to-bits" scenario, claiming that at small sizes the olivine-rich objects should be more abundant when compared with basaltic and iron ones.

A new three-dimensional cobalt phosphate: Co5(OH2)4(HPO4)2(PO4)2

International Nuclear Information System (INIS)

Han Zhangang; Tian Aixiang; Peng Jun; Zhai Xueliang

2006-01-01

A three-dimensional (3D) cobalt phosphate: Co 5 (OH 2 ) 4 (HPO 4 ) 2 (PO 4 ) 2 (1), has been synthesized by hydrothermal reaction and characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and magnetic techniques. The title compound is a template free cobalt phosphate. Compound 1 exhibits a complex net architecture based on edge- and corner-sharing of CoO 6 and PO 4 polyhedra. The magnetic susceptibility measurements indicated that the title compound obeys Curie-Weiss behavior down to a temperature of 17 K at which an antiferromagnetic phase transition occurs. - Graphical abstract: A 3D cobalt phosphate with a neutral framework: Co 5 (OH 2 ) 4 (HPO 4 ) 2 (PO 4 ) 2 (1), has been synthesized and characterized. Compound 1 exhibits a complex net architecture based on edge- and corner-sharing of CoO 6 and PO 4 polyhedra. Its magnetic property was researched

H Diffusion in Olivine and Pyroxene from Peridotite Xenoliths and a Hawaiian Magma Speedometer

Science.gov (United States)

Peslier, A. H.; Bizimis, M.

2014-01-01

Hydrogen is present as a trace element in olivine and pyroxene and its content distribution in the mantle results from melting and metasomatic processes. Here we examine how these H contents can be disturbed during decompression. Hydrogen was analyzed by FTIR in olivine and pyroxene of spinel peridotite xenoliths from Salt Lake Crater (SLC) nephelinites which are part of the rejuvenated volcanism at Oahu (Hawaii) [1,2]. H mobility in pyroxene resulting from spinel exsolution during mantle upwelling Most pyroxenes in SLC peridotites exhibit exsolutions, characterized by spinel inclusions. Pyroxene edges where no exsolution are present have less H then their core near the spinel. Given that H does not enter spinel [3], subsolidus requilibration may have concentrated H in the pyroxene adjacent to the spinel exsolution during mantle upwelling. H diffusion in olivine during xenolith transport by its host magma and host magma ascent rates Olivines have lower water contents at the edge and near fractures compared to at their core, while the concentrations of all other chemical elements appear homogeneous. This suggests that some of the initial water has diffused out of the olivine. Water loss from the olivine is thought to occur during host-magma ascent and xenolith transport to the surface [4-6]. Diffusion modeling matches best the data when the initial water content used is that measured at the core of the olivines, implying that mantle water contents are preserved at the core of the olivines. The 3225 cm(sup -1) OH band at times varies independantly of other OH bands, suggesting uneven H distribution in olivine defects likely acquired during mantle metasomatism just prior to eruption and unequilibrated. Diffusion times (1-48 hrs) combined with depths of peridotite equilibration or of magma start of degassing allow to calculate ascent rates for the host nephelinite of 0.1 to 27 m/s.

Ringwoodite growth rates from olivine with ~75 ppmw H₂O: Metastable olivine must be nearly anhydrous to exist in the mantle transition zone

Energy Technology Data Exchange (ETDEWEB)

Du Frane, Wyatt L. [Arizona State Univ., Tempe, AZ (United States). School of Earth and Space Exploration; Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Atmospheric, Earth and Energy Division; Sharp, Thomas G. [Arizona State Univ., Tempe, AZ (United States). School of Earth and Space Exploration; Mosenfelder, Jed L. [California Inst. of Technology (CalTech), Pasadena, CA (United States). Division of Geological and Planetary Sciences; Leinenweber, Kurt [Arizona State Univ., Tempe, AZ (United States). School of Earth and Space Exploration

2013-04-15

It has been previously demonstrated that as little as 300 ppmw H₂O increases wadsleyite and ringwoodite growth rates to magnitudes that are inconsistent with the metastable olivine hypothesis. To further test this hypothesis, we present new ringwoodite growth rate measurements from olivine with ~75 ppmw H₂O at 18 GPa and 700, 900, and 1100 °C. These growth rates are nearly identical to those from olivine with ~300 ppmw H₂O, and significantly higher than those from nominally anhydrous olivine. We infer that transformation of olivine with 75-300 ppmw H₂O is primarily enhanced by hydrolytic weakening of reaction rims, which reduces the elastic strain-energy barrier to growth. We present a new method for fitting nonlinear nominally anhydrous data, to demonstrate that reduction of growth rates by elastic strain energy is an additional requirement for metastable olivine. In conclusion, based on previous thermokinetic modeling, these enhanced growth rates are inconsistent with the persistence of metastable olivine wedges into the mantle transition zone. Metastable persistence of olivine into the mantle transition-zone would therefore require < 75 ppmw H₂O.

Vaporization Studies of Olivine via Knudsen Effusion Mass Spectrometry

Science.gov (United States)

Costa, G. C. C.; Jacobson, N. S.

2014-01-01

Olivine is the major mineral in the Earth's upper mantle occurring predominantly in igneous rocks and has been identified in meteorites, asteroids, the Moon and Mars. Among many other important applications in planetary and materials sciences, the thermodynamic properties of vapor species from olivine are crucial as input parameters in computational modelling of the atmospheres of hot, rocky exoplanets (lava planets). There are several weight loss studies of olivine vaporization in the literature and one Knudsen Effusion Mass Spectrometry (KEMS) study. In this study, we examine a forsterite-rich olivine (93% forsterite and 7% fayalite, Fo93Fa7) with KEMS to further understand its vaporization and thermodynamic properties.

Potential Temperatures of Sources of MORB, OIB and LIPs Based on AL Partitioning Between Olivine and Spinel

Science.gov (United States)

Sobolev, A. V.; Batanova, V. G.; Krasheninnikov, S.; Borisov, A.; Arndt, N.; Kuzmin, D.; Krivolutskaya, N.; Sushevskaya, N.

2013-12-01

Knowledge of potential temperatures of convecting mantle is required for the understanding the global processes on the Earth [1]. The common way to estimate these is the reconstruction of primary melt compositions and liquidus temperatures based on the Fe-Mg partitioning between olivine and melt. This approach requires knowledge of the compositions of primitive melts in equilibrium with olivine alone as well as composition of olivine equilibrium with primary melts. This information is in most cases unavailable or of questionable quality. Here we report a new approach to obtain crystallization temperatures of primary melts based on the olivine-spinel Al-Cr geothermometer [2]. The advantages of this approach are: (1) low rate of diffusion of Al in the olivine, which promises to preserve high magmatic temperatures and (2) common presence of spinel in assemblage with high-Mg olivine. In order to decipher influence of elevated Ti concentrations in spinel we have run several experiments at high temperatures (1400-1200 degree C), atmospheric pressure and controled oxygen fugacity. We also analysed over two thousand spinel inclusions and high-Mg host olivines from different MORB, OIB, LIP and Archean komatiites on the JXA-8230 EPMA at ISTerre, Grenoble, France. Concentrations of Al, Ti, Na, P, Zn, Cr, Mn, Ca, Co, Ni were determined with a precision of 10 ppm (2 standard errors) using a newly developed protocol [3]. When available, we also analysed matrix glass and glass inclusions in olivine and found that temperature estimations from olivine-spinel (Al-Cr) and olivine-melt (Fe-Mg) [4] equilibrium match within (+/-30 degree C). The results show contrasting crystallization temperatures of Mg-rich olivine of the same Fo content from different types of mantle-derived magmas, from the lowest (down to 1220 degree C) for MORB to the highest (up to 1550 degree C) for komatiites and Siberian meimechites. These results match predictions from Fe-Mg olivine-melt equilibrium and

A new three-dimensional cobalt phosphate: Co 5(OH 2) 4(HPO 4) 2(PO 4) 2

Science.gov (United States)

Han, Zhangang; Tian, Aixiang; Peng, Jun; Zhai, Xueliang

2006-10-01

A three-dimensional (3D) cobalt phosphate: Co 5(OH 2) 4(HPO 4) 2(PO 4) 2 ( 1), has been synthesized by hydrothermal reaction and characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and magnetic techniques. The title compound is a template free cobalt phosphate. Compound 1 exhibits a complex net architecture based on edge- and corner-sharing of CoO 6 and PO 4 polyhedra. The magnetic susceptibility measurements indicated that the title compound obeys Curie-Weiss behavior down to a temperature of 17 K at which an antiferromagnetic phase transition occurs.

Dynamic recrystallization and grain growth in olivine rocks

NARCIS (Netherlands)

Kellermann Slotemaker, A.

2006-01-01

A mechanism based description of the rheology of olivine is essential for modeling of upper mantle geodynamics. Previously, mantle flow has been investigated using flow laws for grain size insensitive (GSI) dislocation creep and/or grain size sensitive (GSS) diffusion creep of olivine. Generally,

Vaporization and thermodynamics of forsterite-rich olivine and some implications for silicate atmospheres of hot rocky exoplanets

Science.gov (United States)

Costa, Gustavo C. C.; Jacobson, Nathan S.; Fegley, Bruce, Jr.

2017-06-01

We describe an experimental and theoretical study of olivine [Mg2SiO4 (Fo)-Fe2SiO4 (Fa)] vaporization. The vaporization behavior and thermodynamic properties of a fosterite-rich olivine (Fo95Fa5) have been explored by high-temperature Knudsen effusion mass spectrometry (KEMS) from 1750 to 2250 K. The gases observed (in order of decreasing partial pressure) are Fe, SiO, Mg, O2 and O. We measured the solidus temperature (∼2050 K), partial pressures of individual gases, the total vapor pressure, and thermodynamic activities and partial molar enthalpies of MgO, 'FeO', and SiO2 for the Fo95Fa5 olivine. The results are compared to other measurements and models of the olivine system. Our experimental data show olivine vaporizes incongruently. We discuss this system both as a psuedo-binary of Fo-Fa and a psuedo-ternary of MgO-'FeO'-SiO2. Iron/magnesium molar ratios in the sample before (∼0.05) and after (∼0.04) vaporization are consistent with the small positive deviations from ideality of fayalite (γ ∼ 1.17) in olivine of the composition studied (e.g., Nafziger and Muan, 1967). Our data for olivine + melt confirm prior theoretical models predicting fractional vaporization of Fe relative to Mg from molten silicates (Fegley and Cameron, 1987; Schaefer and Fegley, 2009; Ito et al., 2015). If loss of silicate atmospheres occurs from hot rocky exoplanets with magma oceans the residual planet may be enriched in magnesium relative to iron.

Diffusion of Water through Olivine and Clinopyroxene: Implications for Melt Inclusion Fidelity

Science.gov (United States)

Plank, T. A.; Lloyd, A. S.; Ferriss, E.

2016-12-01

The maximum H2O concentrations measured in olivine-hosted melt inclusions (MIs) from arc tephra fall within a narrow range of 3-5 wt%. A major question is whether this reflects parental water concentrations or diffusive exchange through the host crystal during storage and ascent. Laboratory experiments have shown that water can diffuse through 500 micron olivine in minutes to days at 1100°C. We have tested these predictions with a natural experiment using volatile (H2O, CO2, S) diffusion along melt embayments to constrain ascent rates during the 1974 eruption of Volcan Fuego to 5-8 minutes from 7 km depth [1]. Thus, olivine-hosted MIs may move from their storage region to the surface during some eruptions rapidly enough to retain almost all of their original water. Only the smallest MIs (500 microns) and large melt inclusions (>50 microns), and 4) rapid post-eruptive cooling (< 1min, clast sizes < 1 cm). The rapid diffusion of H through olivine and cpx presents a challenge to MI fidelity, but not necessarily if the above conditions are met. [1] Lloyd et al., 2014, JVGR. [2] Ferriss et al., 2016, AmMin.

Olivine weathering in soil, and its effects on growth and nutrient uptake in Ryegrass (Lolium perenne L.: a pot experiment.

Directory of Open Access Journals (Sweden)

Hein F M ten Berge

Full Text Available Mineral carbonation of basic silicate minerals regulates atmospheric CO(2 on geological time scales by locking up carbon. Mining and spreading onto the earth's surface of fast-weathering silicates, such as olivine, has been proposed to speed up this natural CO(2 sequestration ('enhanced weathering'. While agriculture may offer an existing infrastructure, weathering rate and impacts on soil and plant are largely unknown. Our objectives were to assess weathering of olivine in soil, and its effects on plant growth and nutrient uptake. In a pot experiment with perennial ryegrass (Lolium perenne L., weathering during 32 weeks was inferred from bioavailability of magnesium (Mg in soil and plant. Olivine doses were equivalent to 1630 (OLIV1, 8150, 40700 and 204000 (OLIV4 kg ha(-1. Alternatively, the soluble Mg salt kieserite was applied for reference. Olivine increased plant growth (+15.6% and plant K concentration (+16.5% in OLIV4. At all doses, olivine increased bioavailability of Mg and Ni in soil, as well as uptake of Mg, Si and Ni in plants. Olivine suppressed Ca uptake. Weathering estimated from a Mg balance was equivalent to 240 kg ha(-1 (14.8% of dose, OLIV1 to 2240 kg ha(-1 (1.1%, OLIV4. This corresponds to gross CO(2 sequestration of 290 to 2690 kg ha(-1 (29 10(3 to 269 10(3 kg km(-2. Alternatively, weathering estimated from similarity with kieserite treatments ranged from 13% to 58% for OLIV1. The Olsen model for olivine carbonation predicted 4.0% to 9.0% weathering for our case, independent of olivine dose. Our % values observed at high doses were smaller than this, suggesting negative feedbacks in soil. Yet, weathering appears fast enough to support the 'enhanced weathering' concept. In agriculture, olivine doses must remain within limits to avoid imbalances in plant nutrition, notably at low Ca availability; and to avoid Ni accumulation in soil and crop.

Olivine CPO in non-deformed peridotite due to topotactic replacement of antigorite

Science.gov (United States)

Nagaya, Takayoshi; Wallis, Simon; Kobayashi, Hiroaki; Michibayashi, Katsuyoshi; Mizukami, Tomoyuki; Seto, Yusuke; Miyake, Akira; Matsumoto, Megumi

2014-05-01

Olivine crystallographic preferred orientation (CPO) is thought to be the main cause of seismic anisotropy in the mantle, and its formation is generally considered to be the result of plastic deformation of mantle by dislocation creep. Olivine CPO has been reproduced in laboratory deformation experiments and considerable success has been achieved in understanding the deformation conditions (e.g. stress, temperature and water content) under which different olivine CPO patterns develop. This opens the possibility of mapping conditions in the mantle using seismic anisotropy and has been the subject of considerable study. Here we report an alternative mechanism for olivine CPO without the need for deformation. This process may be important in understanding the seismic properties of mantle in convergent margins. Metamorphic studies show peridotite in the Happo area, central Japan, formed by the dehydration of antigorite-schist related to contact metamorphism around a granite intrusion. Both field and microstructural observations suggest the olivine has not undergone strong plastic deformation. This was confirmed by TEM work that shows the olivine has very low dislocation densities and lacks low angle tilt boundaries. Such tilt boundaries are general stable even after annealing. These features show that peridotite in the Happo area formed in the absence of solid-state deformation. The olivine of the Happo peridotite formed dominantly by the dehydration breakdown of antigorite schist. We propose that the olivine CPO formed as a result of topotactic replacement of antigorite by the newly formed olivine. EBSD measurements in samples where both antigorite and new olivine are present and in contact show a very close crystallographic relationship between the two minerals: the a-axes are parallel, and the b- and c-axes are perpendicular. We conclude the strong olivine CPO in the Happo area was inherited from the original CPO of the antigorite. Such a process is likely to also

Complex phosphates in the Li(Na)3PO4-InPO4 systems

International Nuclear Information System (INIS)

Potapova, A.M.; Zimina, G.V.; Smirnova, I.N.; Novoselov, A.V.; Spiridonov, F.M.; Stefanovich, S.Yu.

2008-01-01

Subsolidus sections in the systems Li 3 PO 4 -InPO 4 (950 deg C) and Na 3 PO 4 -InPO 4 (800, 900, and 1000 deg C) have been studied by X-ray powder diffraction. The compound Li 3 In(PO 4 ) 2 has been synthesized, and the NASICON-type solid solution Li 3(1-x) In 2+x (PO 4 ) 3 (0.67 ≤ x ≤ 0.80) has been found to exist. In the system Na 3 PO 4 -InPO 4 , the solid solution Na 3(1-x) In x/3 PO 4 (0 ≤ x ≤ 0.2) and two complex phosphates exist: Na 3 In(PO 4 ) 2 and Na 3 In 2 (PO 4 ) 3 . These complex phosphates are dimorphic, with the irreversible-transition temperature equal to 675 and 820 deg C, respectively. Na 3 In(PO 4 ) 2 degrades at 920 deg C. Ionic conductivity has been measured in some phases in the system [ru

Crystal structure of 3,4-dihydroxy-2-butanone 4-phosphate synthase of riboflavin biosynthesis

Energy Technology Data Exchange (ETDEWEB)

Liao, D.-I.; Calabrese, J.C.; Wawrzak, Z.; Viitanen, P.V.; Jordan, D.B. (DuPont); (NWU)

2010-03-05

3,4-Dihydroxy-2-butanone-4-phosphate synthase catalyzes a commitment step in the biosynthesis of riboflavin. On the enzyme, ribulose 5-phosphate is converted to 3,4-dihydroxy-2-butanone 4-phosphate and formate in steps involving enolization, ketonization, dehydration, skeleton rearrangement, and formate elimination. The enzyme is absent in humans and an attractive target for the discovery of antimicrobials for pathogens incapable of acquiring sufficient riboflavin from their hosts. The homodimer of 23 kDa subunits requires Mg{sup 2+} for activity. The first three-dimensional structure of the enzyme was determined at 1.4 {angstrom} resolution using the multiwavelength anomalous diffraction (MAD) method on Escherichia coli protein crystals containing gold. The protein consists of an {alpha} + {beta} fold having a complex linkage of {beta} strands. Intersubunit contacts are mediated by numerous hydrophobic interactions and three hydrogen bond networks. A proposed active site was identified on the basis of amino acid residues that are conserved among the enzyme from 19 species. There are two well-separated active sites per dimer, each of which comprise residues from both subunits. In addition to three arginines and two threonines, which may be used for recognizing the phosphate group of the substrate, the active site consists of three glutamates, two aspartates, two histidines, and a cysteine which may provide the means for general acid and base catalysis and for coordinating the Mg{sup 2+} cofactor within the active site.

Chromium valences in ureilite olivine and implications for ureilite petrogenesis

Science.gov (United States)

Goodrich, C. A.; Sutton, S. R.; Wirick, S.; Jercinovic, M. J.

2013-12-01

Ureilites are a group of ultramafic achondrites commonly thought to be residues of partial melting on a carbon-rich asteroid. They show a large variation in FeO content (olivine Fo values ranging from ∼74 to 95) that cannot be due to igneous fractionation and suggests instead variation in oxidation state. The presence of chromite in only a few of the most ferroan (Fo 75-76) samples appears to support such a model. MicroXANES analyses were used in this study to determine the valence states of Cr (previously unknown) in olivine cores of 11 main group ureilites. The goal of this work was to use a method that is independent of Fo to determine the oxidation conditions under which ureilites formed, in order to evaluate whether the ureilite FeO-variation is correlated with oxidation state, and whether it is nebular or planetary in origin. Two of the analyzed samples, LEW 88774 (Fo 74.2) and NWA 766 (Fo 76.7) contain primary chromite; two others, LAP 03587 (Fo 74.4) and CMS 04048 (Fo 76.2) contain sub-micrometer-sized exsolutions of chromite + Ca-rich pyroxene in olivine; and one, EET 96328 (Fo 85.2) contains an unusual chromite grain of uncertain origin. No chromite has been observed in the remaining six samples (Fo 77.4-92.3). Chromium in olivine in all eleven samples was found to be dominated by the divalent species, with valences ranging from 2.10 ± 0.02 (1σ) to 2.46 ± 0.04. The non-chromite-bearing ureilites have the most reduced Cr, with a weighted mean valence of 2.12 ± 0.01, i.e., Cr2+/Cr3+ = 7.33. All low-Fo chromite-bearing ureilites have more oxidized Cr, with valences ranging from 2.22 ± 0.03 to 2.46 ± 0.04. EET 96328, whose chromite grain we interpret as a late-crystallizing phase, yielded a reduced Cr valence of 2.15 ± 0.07, similar to the non-chromite-bearing samples. Based on the measured Cr valences, magmatic (1200-1300 °C) oxygen fugacities (fO2) of the non-chromite-bearing samples were estimated to be in the range IW-1.9 to IW-2.8 (assuming

Chemical zoning and homogenization of olivines in ordinary chondrites and implications for thermal histories of chondrules

Science.gov (United States)

Miyamoto, Masamichi; Mckay, David S.; Mckay, Gordon A.; Duke, Michael B.

1986-01-01

The extent and degree of homogenization of chemical zoning of olivines in type 3 ordinary chondrites is studied in order to obtain some constraints on cooling histories of chondrites. Based on Mg-Fe and CaO zoning, olivines in type 3 chondrites are classified into four types. A single chondrule usually contains olivines with the same type of zoning. Microporphyritic olivines show all four zoning types. Barred olivines usually show almost homogenized chemical zoning. The cooling rates or burial depths needed to homogenize the chemical zoning are calculated by solving the diffusion equation, using the zoning profiles as an initial condition. Mg-Fe zoning of olivine may be altered during initial cooling, whereas CaO zoning is hardly changed. Barred olivines may be homogenized during initial cooling because their size is relatively small. To simulated microporphyritic olivine chondrules, cooling from just below the liquidus at moderately high rates is preferable to cooling from above the liquidus at low rates. For postaccumulation metamorphism of type 3 chondrites to keep Mg-Fe zoning unaltered, the maximum metamorphic temperature must be less than about 400 C if cooling rates based on Fe-Ni data are assumed. Calculated cooling rates for both Fa and CaO homogenization are consistent with those by Fe-Ni data for type 4 chondrites. A hot ejecta blanket several tens of meters thick on the surface of a parent body is sufficient to homogenize Mg-Fe zoning if the temperature of the blanket is 600-700 C. Burial depths for petrologic types of ordinary chondrites in a parent body heated by Al-26 are broadly consistent with those previously proposed.

Recent progress and developments in lithium cobalt phosphate chemistry- Syntheses, polymorphism and properties

Science.gov (United States)

Ludwig, Jennifer; Nilges, Tom

2018-04-01

This review summarizes the development, investigation, and optimization of polymorphic lithium cobalt phosphate LiCoPO4. One of the three polymorphs known to date, olivine-type or Pnma-LiCoPO4, shows intriguing electrochemical properties as a high-voltage cathode material, which are of interest for next-generation lithium-ion batteries with higher energy density. Hence, scientists have developed optimization strategies to improve its performance for commercial applications. Herein, a number of procedures for the synthesis of Pnma-LiCoPO4 is presented, including thermodynamic as well as kinetically controlled approaches. The continuous improvement of its electrochemical performance is illustrated, which was realized by the development of solvothermal techniques that allow a precise particle size and morphology control. In the course of these investigations, two new polymorphs, Pna21-LiCoPO4 and Cmcm-LiCoPO4, have been discovered which show different physical and structural properties compared to Pnma-LiCoPO4. Despite their significantly poorer electrochemical performance, these polymorphs allow interesting insights into the variable structure chemistry of transition-metal phosphates, which canalizes in intriguing magnetic and thermal properties. The similarities and differences in the chemical and physical properties of Pnma-LiCoPO4, Pna21-LiCoPO4, and Cmcm-LiCoPO4 are discussed.

Transfer of olivine crystallographic orientation through a cycle of serpentinisation and dehydration

Science.gov (United States)

Dunkel, Kristina G.; Austrheim, Håkon; Ildefonse, Benoit; Jamtveit, Bjørn

2017-08-01

Our ability to decipher the mechanisms behind metamorphic transformation processes depends in a major way on the extent to which crystallographic and microstructural information is transferred from one stage to another. Within the Leka Ophiolite Complex in the Central Norwegian Caledonides, prograde olivine veins that formed by dehydration of serpentinite veins in dunites exhibit a characteristic distribution of microstructures: The outer part of the veins comprises coarse-grained olivine that forms an unusual, brick-like microstructure. The inner part of the veins, surrounding a central fault, is composed of fine-grained olivine. Where the fault movement included a dilational component, optically clear, equant olivine occurs in the centre. Electron backscatter diffraction mapping reveals that the vein olivine has inherited its crystallographic preferred orientation (CPO) from the olivine in the porphyroclastic host rock; however, misorientation is weaker and associated to different rotation axes. We propose that prograde olivine grew epitaxially on relics of mantle olivine and thereby acquired its CPO. Growth towards pre-existing microfractures along which serpentinisation had occurred led to straight grain boundaries and a brick-like microstructure in the veins. When dehydration embrittlement induced slip, a strong strain localisation on discrete fault planes prevented distortion of the CPO due to cataclastic deformation; grain size reduction did not significantly modify the olivine CPO. This illustrates how a CPO can be preserved though an entire metamorphic cycle, including hydration, dehydration, and deformation processes, and that the CPO and the microstructures (e.g. grain shape) of one phase do not necessarily record the same event.

Abiotic methane formation during experimental serpentinization of olivine.

Science.gov (United States)

McCollom, Thomas M

2016-12-06

Fluids circulating through actively serpentinizing systems are often highly enriched in methane (CH 4 ). In many cases, the CH 4 in these fluids is thought to derive from abiotic reduction of inorganic carbon, but the conditions under which this process can occur in natural systems remain unclear. In recent years, several studies have reported abiotic formation of CH 4 during experimental serpentinization of olivine at temperatures at or below 200 °C. However, these results seem to contradict studies conducted at higher temperatures (300 °C to 400 °C), where substantial kinetic barriers to CH 4 synthesis have been observed. Here, the potential for abiotic formation of CH 4 from dissolved inorganic carbon during olivine serpentinization is reevaluated in a series of laboratory experiments conducted at 200 °C to 320 °C. A 13 C-labeled inorganic carbon source was used to unambiguously determine the origin of CH 4 generated in the experiments. Consistent with previous high-temperature studies, the results indicate that abiotic formation of CH 4 from reduction of dissolved inorganic carbon during the experiments is extremely limited, with nearly all of the observed CH 4 derived from background sources. The results indicate that the potential for abiotic synthesis of CH 4 in low-temperature serpentinizing environments may be much more limited than some recent studies have suggested. However, more extensive production of CH 4 was observed in one experiment performed under conditions that allowed an H 2 -rich vapor phase to form, suggesting that shallow serpentinization environments where a separate gas phase is present may be more favorable for abiotic synthesis of CH 4 .

Network topology of olivine-basalt partial melts

Science.gov (United States)

Skemer, Philip; Chaney, Molly M.; Emmerich, Adrienne L.; Miller, Kevin J.; Zhu, Wen-lu

2017-07-01

The microstructural relationship between melt and solid grains in partially molten rocks influences many physical properties, including permeability, rheology, electrical conductivity and seismic wave speeds. In this study, the connectivity of melt networks in the olivine-basalt system is explored using a systematic survey of 3-D X-ray microtomographic data. Experimentally synthesized samples with 2 and 5 vol.% melt are analysed as a series of melt tubules intersecting at nodes. Each node is characterized by a coordination number (CN), which is the number of melt tubules that intersect at that location. Statistically representative volumes are described by coordination number distributions (CND). Polyhedral grains can be packed in many configurations yielding different CNDs, however widely accepted theory predicts that systems with small dihedral angles, such as olivine-basalt, should exhibit a predominant CN of four. In this study, melt objects are identified with CN = 2-8, however more than 50 per cent are CN = 4, providing experimental verification of this theoretical prediction. A conceptual model that considers the role of heterogeneity in local grain size and melt fraction is proposed to explain the formation of nodes with CN ≠ 4. Correctly identifying the melt network topology is essential to understanding the relationship between permeability and porosity, and hence the transport properties of partial molten mantle rocks.

Carbon determination in natural crystals of olivines of deeporigin

International Nuclear Information System (INIS)

Shilobreeva, S.N.; Kadik, A.A.; Minaev, V.M.; Kazakov, S.S.; Kuz'min, L.E.; Moskovskij Inzhenerno-Fizicheskij Inst.; AN SSSR, Moscow. Inst. Yadernykh Issledovanij)

1987-01-01

Activation analysis and nuclear reaction analysis with registration of energy spectrum of forming prompt particles are used to determine carbon concentration and distribution in monocrystals of olivines. Carbon determination in olivine volume was carried out by activation analysis by 12 C(d, n) 13 N reaction and surface content - by registration of protons resulting from 12 C(d, p) 13 C reaction. The deuteron energy being 1.8-2.7 MeV, carbon determination limit and the analysis error were 10 -3 and 20 relat.%, respectively. By means of IR spectroscopy it is shown that carbon constitutes part of crystal lattice of olivines in monatomic form

Diffusion-driven magnesium and iron isotope fractionation in Hawaiian olivine

Science.gov (United States)

Teng, F.-Z.; Dauphas, N.; Helz, R.T.; Gao, S.; Huang, S.

2011-01-01

Diffusion plays an important role in Earth sciences to estimate the timescales of geological processes such as erosion, sediment burial, and magma cooling. In igneous systems, these diffusive processes are recorded in the form of crystal zoning. However, meaningful interpretation of these signatures is often hampered by the fact that they cannot be unambiguously ascribed to a single process (e.g., magmatic fractionation, diffusion limited transport in the crystal or in the liquid). Here we show that Mg and Fe isotope fractionations in olivine crystals can be used to trace diffusive processes in magmatic systems. Over sixty olivine fragments from Hawaiian basalts show isotopically fractionated Mg and Fe relative to basalts worldwide, with up to 0.4??? variation in 26Mg/24Mg ratios and 1.6??? variation in 56Fe/54Fe ratios. The linearly and negatively correlated Mg and Fe isotopic compositions [i.e., ??56Fe=(??3.3??0.3)????26Mg], co-variations of Mg and Fe isotopic compositions with Fe/Mg ratios of olivine fragments, and modeling results based on Mg and Fe elemental profiles demonstrate the coupled Mg and Fe isotope fractionation to be a manifestation of Mg-Fe inter-diffusion in zoned olivines during magmatic differentiation. This characteristic can be used to constrain the nature of mineral zoning in igneous and metamorphic rocks, and hence determine the residence times of crystals in magmas, the composition of primary melts, and the duration of metamorphic events. With improvements in methodology, in situ isotope mapping will become an essential tool of petrology to identify diffusion in crystals. ?? 2011 Elsevier B.V.

Mantle-derived trace element variability in olivines and their melt inclusions

Science.gov (United States)

Neave, David A.; Shorttle, Oliver; Oeser, Martin; Weyer, Stefan; Kobayashi, Katsura

2018-02-01

Trace element variability in oceanic basalts is commonly used to constrain the physics of mantle melting and the chemistry of Earth's deep interior. However, the geochemical properties of mantle melts are often overprinted by mixing and crystallisation processes during ascent and storage. Studying primitive melt inclusions offers one solution to this problem, but the fidelity of the melt-inclusion archive to bulk magma chemistry has been repeatedly questioned. To provide a novel check of the melt inclusion record, we present new major and trace element analyses from olivine macrocrysts in the products of two geographically proximal, yet compositionally distinct, primitive eruptions from the Reykjanes Peninsula of Iceland. By combining these macrocryst analyses with new and published melt inclusion analyses we demonstrate that olivines have similar patterns of incompatible trace element (ITE) variability to the inclusions they host, capturing chemical systematics on intra- and inter-eruption scales. ITE variability (element concentrations, ratios, variances and variance ratios) in olivines from the ITE-enriched Stapafell eruption is best accounted for by olivine-dominated fractional crystallisation. In contrast, ITE variability in olivines and inclusions from the ITE-depleted Háleyjabunga eruption cannot be explained by crystallisation alone, and must have originated in the mantle. Compatible trace element (CTE) variability is best described by crystallisation processes in both eruptions. Modest correlations between host and inclusion ITE contents in samples from Háleyjabunga suggest that melt inclusions can be faithful archives of melting and magmatic processes. It also indicates that degrees of ITE enrichment can be estimated from olivines directly when melt inclusion and matrix glass records of geochemical variability are poor or absent. Inter-eruption differences in olivine ITE systematics between Stapafell and Háleyjabunga mirror differences in melt

Aqueous synthesis of LiFePO4 with Fractal Granularity

OpenAIRE

Cab?n-Huertas, Zahilia; Ayyad, Omar; Dubal, Deepak P.; G?mez-Romero, Pedro

2016-01-01

Lithium iron phosphate (LiFePO4) electrodes with fractal granularity are reported. They were made from a starting material prepared in water by a low cost, easy and environmentally friendly hydrothermal method, thus avoiding the use of organic solvents. Our method leads to pure olivine phase, free of the impurities commonly found after other water-based syntheses. The fractal structures consisted of nanoparticles grown into larger micro-sized formations which in turn agglomerate leading to hi...

Synthesis and electrochemical properties of olivine LiFePO{sub 4} prepared by a carbothermal reduction method

Energy Technology Data Exchange (ETDEWEB)

Liu, Hui-ping; Wang, Zhi-xing; Li, Xin-hai; Guo, Hua-jun; Peng, Wen-jie; Zhang, Yun-he; Hu, Qi-yang [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China)

2008-10-01

LiFePO{sub 4}/C composite cathode material was prepared by carbothermal reduction method, which uses NH{sub 4}H{sub 2}PO{sub 4}, Li{sub 2}CO{sub 3} and cheap Fe{sub 2}O{sub 3} as starting materials, acetylene black and glucose as carbon sources. The precursor of LiFePO{sub 4}/C was characterized by differential thermal analysis and thermogravimetry. X-ray diffraction (XRD), scanning electron microscopy (SEM) micrographs showed that the LiFePO{sub 4}/C is olivine-type phase, and the addition of the carbon reduced the LiFePO{sub 4} grain size. The carbon is dispersed between the grains, ensuring a good electronic contact. The products sintered at 700 C for 8 h with glucose as carbon source possessed excellent electrochemical performance. The synthesized LiFePO{sub 4} composites showed a high electrochemical capacity of 159.3 mAh g{sup -1} at 0.1C rate, and the capacity fading is only 2.2% after 30 cycles. (author)

Imaging phosphatidylinositol 4-phosphate dynamics in living plant cells

NARCIS (Netherlands)

Vermeer, J.E.M.; Thole, J.M.; Goedhart, J.; Nielsen, E.; Munnik, T.; Gadella, T.W.J.

2009-01-01

Polyphosphoinositides represent a minor group of phospholipids, accounting for less than 1% of the total. Despite their low abundance, these molecules have been implicated in various signalling and membrane trafficking events. Phosphatidylinositol 4-phosphate (PtdIns4P) is the most abundant

Biosynthesis of ribose-5-phosphate and erythrose-4-phosphate in archaea: a phylogenetic analysis of archaeal genomes

Directory of Open Access Journals (Sweden)

Tim Soderberg

2005-01-01

Full Text Available A phylogenetic analysis of the genes encoding enzymes in the pentose phosphate pathway (PPP, the ribulose monophosphate (RuMP pathway, and the chorismate pathway of aromatic amino acid biosynthesis, employing data from 13 complete archaeal genomes, provides a potential explanation for the enigmatic phylogenetic patterns of the PPP genes in archaea. Genomic and biochemical evidence suggests that three archaeal species (Methanocaldococcus jannaschii, Thermoplasma acidophilum and Thermoplasma volcanium produce ribose-5-phosphate via the nonoxidative PPP (NOPPP, whereas nine species apparently lack an NOPPP but may employ a reverse RuMP pathway for pentose synthesis. One species (Halobacterium sp. NRC-1 lacks both the NOPPP and the RuMP pathway but may possess a modified oxidative PPP (OPPP, the details of which are not yet known. The presence of transketolase in several archaeal species that are missing the other two NOPPP genes can be explained by the existence of differing requirements for erythrose-4-phosphate (E4P among archaea: six species use transketolase to make E4P as a precursor to aromatic amino acids, six species apparently have an alternate biosynthetic pathway and may not require the ability to make E4P, and one species (Pyrococcus horikoshii probably does not synthesize aromatic amino acids at all.

Hydration-reduced lattice thermal conductivity of olivine in Earth's upper mantle.

Science.gov (United States)

Chang, Yun-Yuan; Hsieh, Wen-Pin; Tan, Eh; Chen, Jiuhua

2017-04-18

Earth's water cycle enables the incorporation of water (hydration) in mantle minerals that can influence the physical properties of the mantle. Lattice thermal conductivity of mantle minerals is critical for controlling the temperature profile and dynamics of the mantle and subducting slabs. However, the effect of hydration on lattice thermal conductivity remains poorly understood and has often been assumed to be negligible. Here we have precisely measured the lattice thermal conductivity of hydrous San Carlos olivine (Mg 0.9 Fe 0.1 ) 2 SiO 4 (Fo90) up to 15 gigapascals using an ultrafast optical pump-probe technique. The thermal conductivity of hydrous Fo90 with ∼7,000 wt ppm water is significantly suppressed at pressures above ∼5 gigapascals, and is approximately 2 times smaller than the nominally anhydrous Fo90 at mantle transition zone pressures, demonstrating the critical influence of hydration on the lattice thermal conductivity of olivine in this region. Modeling the thermal structure of a subducting slab with our results shows that the hydration-reduced thermal conductivity in hydrated oceanic crust further decreases the temperature at the cold, dry center of the subducting slab. Therefore, the olivine-wadsleyite transformation rate in the slab with hydrated oceanic crust is much slower than that with dry oceanic crust after the slab sinks into the transition zone, extending the metastable olivine to a greater depth. The hydration-reduced thermal conductivity could enable hydrous minerals to survive in deeper mantle and enhance water transportation to the transition zone.

A general solution-chemistry route to the synthesis LiMPO4 (M=Mn, Fe, and Co) nanocrystals with [010] orientation for lithium ion batteries

International Nuclear Information System (INIS)

Su Jing; Wei Bingqing; Rong Jiepeng; Yin Wenyan; Ye Zhixia; Tian Xianqing; Ren Ling; Cao Minhua; Hu Changwen

2011-01-01

A general and efficient solvothermal strategy has been developed for the preparation of lithium transition metal phosphate microstructures (LiMnPO 4 , LiFePO 4 , and LiCoPO 4 ), employing ethanol as the solvent, LiI as the Li source, metal salts as the M sources, H 3 PO 4 as the phosphorus source, and poly(vinyl pyrrolidone) (PVP) as the carbon source and template. This route features low cost, environmental benign, and one-step process for the cathode material production of Li-ion batteries without any complicated experimental setups and sophisticated operations. The as-synthesized LiMPO 4 microstructures exhibit unique, well-shaped and favorable structures, which are self-assembled from microplates or microrods. The b axis is the preferred crystal growth orientation of the products, resulting in a shorter lithium ion diffusion path. The LiFePO 4 microstructures show an excellent cycling stability without capacity fading up to 50 cycles when they are used as a cathode material in lithium-ion batteries. - Graphical abstract: A general and efficient solvothermal strategy has been developed for the preparation of lithium transition metal phosphate microstructures under solvothermal conditions in the presence of PVP. Highlights: → A general and efficient solvothermal strategy has been developed for the preparation of LiMPO 4 microstructures. → This route features low cost, environmental benign, and one-step process. → The LiMPO 4 microstructures exhibit unique, well-shaped, and favorable structures. → The LiFePO 4 microstructures show an excellent cycling stability up to 50 cycles as a cathode material of lithium-ion batteries.

Osh4p exchanges sterols for phosphatidylinositol 4-phosphate between lipid bilayers

OpenAIRE

de Saint-Jean, Maud; Delfosse, Vanessa; Douguet, Dominique; Chicanne, Gaetan; Payrastre, Bernard; Bourguet, William; Antonny, Bruno; Drin, Guillaume

2011-01-01

Osh/Orp proteins transport sterols between organelles and are involved in phosphoinositide metabolism. The link between these two aspects remains elusive. Using novel assays, we address the influence of membrane composition on the ability of Osh4p/Kes1p to extract, deliver, or transport dehydroergosterol (DHE). Surprisingly, phosphatidylinositol 4-phosphate (PI(4)P) specifically inhibited DHE extraction because PI(4)P was itself efficiently extracted by Osh4p. We solve the structure of the Os...

Chemoorganotrophic Bioleaching of Olivine for Nickel Recovery

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Yi Wai Chiang

2014-06-01

Full Text Available Bioleaching of olivine, a natural nickel-containing magnesium-iron-silicate, was conducted by applying chemoorganotrophic bacteria and fungi. The tested fungus, Aspergillus niger, leached substantially more nickel from olivine than the tested bacterium, Paenibacillus mucilaginosus. Aspergillus niger also outperformed two other fungal species: Humicola grisae and Penicillium chrysogenum. Contrary to traditional acid leaching, the microorganisms leached nickel preferentially over magnesium and iron. An average selectivity factor of 2.2 was achieved for nickel compared to iron. The impact of ultrasonic conditioning on bioleaching was also tested, and it was found to substantially increase nickel extraction by A. niger. This is credited to an enhancement in the fungal growth rate, to the promotion of particle degradation, and to the detachment of the stagnant biofilm around the particles. Furthermore, ultrasonic conditioning enhanced the selectivity of A. niger for nickel over iron to a value of 3.5. Pre-carbonating the olivine mineral, to enhance mineral liberation and change metal speciation, was also attempted, but did not result in improvement as a consequence of the mild pH of chemoorganotrophic bioleaching.

Formation of Diastereoisomeric Piperazine-2,5-dione from dl-Alanine in the Presence of Olivine and Water

Science.gov (United States)

Fuchida, Shigeshi; Naraoka, Hiroshi; Masuda, Harue

2017-03-01

dl-Alanine (Ala) was heated with/without powdered olivine and water at 120 °C for 8 days to investigate the formation of the diastereoisomers of piperazine-2,5-dione (diketopiperazine, DKP). When only dl-Ala was heated with a small amount of water, 3.0 % of dl-Ala changed to cis- and trans-DKP after 8 days. DKPs were not detected after heating when no water was added. The presence of a small amount of water is important factor controlling peptide production rates under thermal conditions. When DL-Ala was heated with olivine powder for 8 days, the yields of cis- and trans-DKP were 6.8 and 4.9 %, respectively. The high yield of cis-DKP compared with trans-DKP was attributed to greater thermal stability of cis-DKP. After heating for 8 days, the diastereoisomeric excess of cis-DKP without olivine was 7.3 %, whereas a much higher value of 16.3 % was obtained in the presence of olivine. Taken together, these results show that olivine is not only an efficient catalyst for the formation of DKPs but that it also play a significant role in determining the diastereoisomer selectivity of these cyclic dipeptides.

Origin of spinel lamella and/or inclusions in olivine of harzburgite form the Pauza ultramafic rocks from the Kurdistan region, northeastern Iraq

Science.gov (United States)

Mohammad, Y.; Maekawa, H.; Karim, K.

2009-04-01

Exsolution lamellae and octahedral inclusions of chromian spinel occur in olivine of harzburgite of the Pauza ultramafic rocks, Kurdistan region, northeastern Iraq. The lamella is up to 80μm long and up to 50 μm wide. The lamellae and octahedral inclusions of chromian spinel are distributed heterogeneously in the host olivine crystal. They are depleted in Al2O3 relative to the subhedral spinel grains in the matrix and spinel lamella in orthopyroxene. Olivine (Fo92 - 93) with spinel lamellae occurs as fine-grained crystals around orthopyroxene, whereas olivine (Fo90-91) free from spinel is found in matrix. Based on back-scattered images analyses, enrichments of both Cr # and Fe+3 in the chromian spinel lamella in olivine (replacive olivine) relative to that in adjacent orthopyroxene. As well as the compositions of chromian spinel lamellae host olivine are more Mg-rich than the matrix olivine. Furthermore the restriction of olivine with spinel lamellae and octahedral inclusions on around orthopyroxene, and the similarity of spinel lamella orientations in both olivine and adjacent orthopyroxene. This study concludes that the spinel inclusions in olivine are remnant (inherited from former orthopyroxene) spinel exsolution lamella in orthopyroxene, that has been formed in upper mantle conditions ( T = 1200 °C, P = 2.5 GPa ). Replacive olivine are formed by reaction of ascending silica poor melt and orthopyroxene in harzburgite as pressure decrease the solubility of silica-rich phase (orthopyroxene) in the system increase, therefore ascending melt dissolve pyroxene with spinel exsolution lamella and precipitate replacive olivine with spinel inclusions. We can conclude that the olivines with spinel lamella are not necessary to be original and presenting ultrahigh-pressure and/or ultra deep-mantle conditions as previously concluded. It has been formed by melting of orthopyroxene (orthopyroxene with spinel exsolution lamella = olivine with spinel lamellae and octahedral

Band structure analysis on olivine LiMPO{sub 4} and delithiated MPO{sub 4} (M = Fe, Mn) cathode materials

Energy Technology Data Exchange (ETDEWEB)

Yi, Ting-Feng, E-mail: tfyihit@163.com [School of Chemistry and Chemical Engineering, Anhui University of Technology, Maanshan, Anhui 243002 (China); Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080 (China); Fang, Zi-Kui [School of Chemistry and Chemical Engineering, Anhui University of Technology, Maanshan, Anhui 243002 (China); Xie, Ying, E-mail: xieying@hlju.edu.cn [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080 (China); Zhu, Yan-Rong [School of Chemistry and Chemical Engineering, Anhui University of Technology, Maanshan, Anhui 243002 (China); Dai, Changsong [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China)

2014-12-25

Highlights: • The conductivity of Li{sub x}MPO{sub 4} were discussed relying on first principles technique. • Relationship between structure properties and microscopic bonding was addressed. • A mechanism responsible for the structural instability of MnPO{sub 4} was proposed. - Abstract: Olivine compounds, i.e. Li{sub x}MPO{sub 4} (M = Fe, Mn), are now regarded as the most competitive positive-electrode materials for future applications of large-scale rechargeable lithium batteries. There are significant interests in their electronic structures, because the microscopic information is very important for elucidating the structural stability, electrochemical performance, and electronic conductivity issues of batteries for high-rate applications. The structure stabilities of LiMPO{sub 4} and MPO{sub 4} (M = Fe, Mn) cathode materials are analyzed according to first principles calculations. The result shows that LiMPO{sub 4} (M = Fe, Mn) materials exhibit good structure stability, which is mainly contributed to the extremely strong P-O covalent bonds. Furthermore, the introduction of P ions is also helpful for the chemical potential decrease of the materials. The band structure analysis reveals that the electronic conductance of LiFePO{sub 4}, LiMnPO{sub 4}, and FePO{sub 4} is poor, while MnPO{sub 4} possesses half metallic property. According to the electron distribution, it can be confirmed that Mn-O(II) bonds are weakened after Li{sup +} extractions, which is different from the variation trend of Fe-O(II) bonds. The decrease of Mn-O(II) bond strength is thus favorable for the phase transformation observed in experiments.

Olivine in Martian Meteorite Allan Hills 84001: Evidence for a High-Temperature Origin and Implications for Signs of Life

Science.gov (United States)

Shearer, C. K.; Leshin, L. A.; Adcock, C. T.

1999-01-01

Olivine from Martian meteorite Allan Hills (ALH) 84001 occurs as clusters within orthopyroxene adjacent to fractures containing disrupted carbonate globules and feldspathic shock glass. The inclusions are irregular in shape and range in size from approx. 40 microns to submicrometer. Some of the inclusions are elongate and boudinage-like. The olivine grains are in sharp contact with the enclosing orthopyroxene and often contain small inclusions of chromite The olivine exhibits a very limited range of composition from Fo(sub 65) to Fo(sub 66) (n = 25). The delta(sup 18)O values of the olivine and orthopyroxene analyzed by ion microprobe range from +4.3 to +5.3% and are indistinguishable from each other within analytical uncertainty. The mineral chemistries, O-isotopic data, and textural relationships indicate that the olivine inclusions were produced at a temperature greater than 800 C. It is unlikely that the olivines formed during the same event that gave rise to the carbonates in ALH 84001, which have more elevated and variable delta(sup 18)O values, and were probably formed from fluids that were not in isotopic equilibrium with the orthopyroxene or olivine The reactions most likely instrumental in the formation of olivine could be either the dehydration of hydrous silicates that formed during carbonate precipitation or the reduction of orthopyroxene and spinel If the olivine was formed by either reaction during a postcarbonate beating event, the implications are profound with regards to the interpretations of McKay et al. Due to the low diffusion rates in carbonates, this rapid, high-temperature event would have resulted in the preservation of the fine-scale carbonate zoning' while partially devolatilizing select carbonate compositions on a submicrometer scale. This may have resulted in the formation of the minute magnetite grains that McKay et al attributed to biogenic activity.

Unexpected formation by pulsed laser deposition of nanostructured Fe/olivine thin films on MgO substrates

International Nuclear Information System (INIS)

Legrand, C.; Dupont, L.; Davoisne, C.; Le Marrec, F.; Perriere, J.; Baudrin, E.

2011-01-01

Olivine-type LiFePO 4 thin films were grown on MgO (1 0 0) substrates by pulsed laser deposition (PLD). The formation of an original nanostructure is evidenced by transmission electron microscopy measurements. Indeed, on focused ion beam prepared cross sections of the thin film, we observe, the amazing formation of metallic iron/olivine nanostructures. The appearance of such a structure is explained owing to a topotactic relation between the two phases as well as a strong Mg diffusion from the substrate to the film surface. Magnesium migration is thus concomitant with the creation of metallic iron domains that grow from the core of the film to the surface leading to large protuberances. To the best of our knowledge, this is the first report on iron extrusion from the olivine-type LiFePO 4 . -- Graphical Abstract: HRTEM image of olivine/Fe nanostructure obtained by PLD. Display Omitted Research highlights: → This manuscript describes the attempt to prepare textured LiFePO 4 by PLD. This is presently a challenge to better understand the physical properties of the material, used as cathode in lithium ion batteries. → We describe for the first time the iron extrusion from this material. Indeed, there were recent reports on the possible non-stoichiometry, i.e. lithium or oxygen. However, on the iron side, only some defect were observed for hydrothermally prepared material but the extrusion is new in this paper. → We prepared interesting nanostructures which could be used for different fundamental studies: electric and magnetic measurements.

Diffusion Modeling of Cooling Rates of Relict Olivine in Semarkona Chondrules

Science.gov (United States)

Hewins, R. H.; Ganguly, J.; Mariani, E.

2009-03-01

Diffusive exchange profiles between relict olivine and melt-grown olivine in Semarkona Type IIA chondrules were oriented by EBSD to correct D. Results for Fe-Mg (D from Dohmen) and Cr (Ito and Ganguly) are concordant at 300°-400°C/hr.

Remote compositional analysis of lunar olivine-rich lithologies with Moon Mineralogy Mapper (M3) spectra

Science.gov (United States)

Isaacson, P.J.; Pieters, C.M.; Besse, S.; Clark, R.N.; Head, J.W.; Klima, R.L.; Mustard, J.F.; Petro, N.E.; Staid, M.I.; Sunshine, J.M.; Taylor, L.A.; Thaisen, K.G.; Tompkins, S.

2011-01-01

A systematic approach for deconvolving remotely sensed lunar olivine-rich visible to near-infrared (VNIR) reflectance spectra with the Modified Gaussian Model (MGM) is evaluated with Chandrayaan-1 Moon Mineralogy Mapper (M 3) spectra. Whereas earlier studies of laboratory reflectance spectra focused only on complications due to chromite inclusions in lunar olivines, we develop a systematic approach for addressing (through continuum removal) the prominent continuum slopes common to remotely sensed reflectance spectra of planetary surfaces. We have validated our continuum removal on a suite of laboratory reflectance spectra. Suites of olivine-dominated reflectance spectra from a small crater near Mare Moscoviense, the Copernicus central peak, Aristarchus, and the crater Marius in the Marius Hills were analyzed. Spectral diversity was detected in visual evaluation of the spectra and was quantified using the MGM. The MGM-derived band positions are used to estimate the olivine's composition in a relative sense. Spectra of olivines from Moscoviense exhibit diversity in their absorption features, and this diversity suggests some variation in olivine Fe/Mg content. Olivines from Copernicus are observed to be spectrally homogeneous and thus are predicted to be more compositionally homogeneous than those at Moscoviense but are of broadly similar composition to the Moscoviense olivines. Olivines from Aristarchus and Marius exhibit clear spectral differences from those at Moscoviense and Copernicus but also exhibit features that suggest contributions from other phases. If the various precautions discussed here are weighed carefully, the methods presented here can be used to make general predictions of absolute olivine composition (Fe/Mg content). Copyright ?? 2011 by the American Geophysical Union.

New lithium ion batteries exploiting conversion/alloying anode and LiFe0.25Mn0.5Co0.25PO4 olivine cathode

International Nuclear Information System (INIS)

Lecce, Daniele Di; Verrelli, Roberta; Hassoun, Jusef

2016-01-01

Highlights: • New Li-ion batteries are reported. • LiFe 0.25 Mn 0.5 Co 0.25 PO 4 olivine is used as the cathode. • Either Sn-C or Sn-Fe 2 O 3 -C composites are used as anodes. • The electrode/electrolyte interfaces are monitored by EIS. • The systems are considered suitable for energy storage - Abstract: New Li-ion cells are formed by combining a LiFe 0.25 Mn 0.5 Co 0.25 PO 4 olivine cathode either with Sn-Fe 2 O 3 -C or with Sn-C composite anodes. These active materials exhibit electrochemical properties very attractive in view of practical use, including the higher working voltage of the LiFe 0.25 Mn 0.5 Co 0.25 PO 4 cathode with respect to conventional LiFePO 4 , as well as the remarkable capacity and rate capability of Sn-Fe 2 O 3 -C and Sn-C anodes. The stable electrode/electrolyte interfaces, demonstrated by electrochemical impedance spectroscopy, along with proper mass balancing and anode pre-lithiation, allow stable galvanostatic cycling of the full cells. The two batteries, namely Sn-Fe 2 O 3 -C/LiFe 0.25 Mn 0.5 Co 0.25 PO 4 and Sn-C/LiFe 0.25 Mn 0.5 Co 0.25 PO 4 , reversibly operate revealing promising electrochemical features in terms of delivered capacity, working voltage and stability, thus suggesting these electrodes combinations as suitable alternatives for an efficient energy storage.

Investigating dissolution of mechanically activated olivine for carbonation purposes

International Nuclear Information System (INIS)

Haug, Tove Anette; Kleiv, Rolf Arne; Munz, Ingrid Anne

2010-01-01

Research highlights: → Dissolution of mechanically activated olivine increased with 3 orders of magnitude. → Crystallinity changes of olivine is important for the observed dissolution rates. → Activation probably decreases with the degree of dissolution of each particle. - Abstract: Mineral carbonation is one of several alternatives for CO 2 sequestration and storage. The reaction rates of appropriate minerals with CO 2 , for instance olivine and serpentine with vast resources, are relatively slow in a CO 2 sequestration context and the rates have to be increased to make mineral carbonation a good storage alternative. Increasing the dissolution rate of olivine has been the focus of this paper. Olivine was milled with very high energy intensity using a laboratory planetary mill to investigate the effect of mechanical activation on the Mg extraction potential of olivine in 0.01 M HCl solution at room temperature and pressure. Approximately 30-40% of each sample was dissolved and water samples were taken at the end of each experiment. The pH change was used to calculate time series of the Mg concentrations, which also were compared to the final Mg concentrations in the water samples. Percentage dissolved and the specific reaction rates were estimated from the Mg concentration time series. The measured particle size distributions could not explain the rate constants found, but the specific surface area gave a good trend versus dissolution for samples milled wet and the samples milled with a small addition of water. The samples milled dry had the lowest measured specific surface areas ( 2 /g), but had the highest rate constants. The crystallinity calculated from X-ray diffractograms, was the material parameter with the best fit for the observed differences in the rate constants. Geochemical modelling of mechanically activated materials indicated that factors describing the changes in the material properties related to the activation must be included. The

Possible Association of Ferrous Phosphates and Ferric Sulfates in S-rich Soil on Mars

Science.gov (United States)

Mao, J.; Schroeder, C.; Haderlein, S.

2012-12-01

NASA Mars Exploration Rover (MER) Spirit explored Gusev Crater to look for signs of ancient aqueous activity, assess past environmental conditions and suitability for life. Spirit excavated light-toned, S-rich soils at several locations. These are likely of hydrothermal, possibly fumarolic origin. At a location dubbed Paso Robles the light-toned soil was also rich in P - a signature from surrounding rock. While S is mainly bound in ferric hydrated sulfates [1], the mineralogy of P is ill-constrained [2]. P is a key element for life and its mineralogy constrains its availability. Ferrous phases observed in Paso Robles Mössbauer spectra may represent olivine and pyroxene from surrounding basaltic soil [1] or ferrous phosphate minerals [3]. Phosphate is well-known to complex and stabilize Fe 2+ against oxidation to Fe 3+ . Schröder et al. [3] proposed a formation pathway of ferrous phosphate/ferric sulfate associations: sulfuric acid reacts with basalt containing apatite, forming CaSO4 and phosphoric acid. The phosphoric and/or excess sulfuric acid reacts with olivine, forming Fe2+-phosphate and sulfate. The phosphate is less soluble and precipitates. Ferrous sulfate remains in solution and is oxidized as pH increases. To verify this pathway, we dissolved Fe2+-chloride and Na-phosphate salts in sulfuric acid inside an anoxic glovebox. The solution was titrated to pH 6 by adding NaOH when a first precipitate formed, which was ferrous phosphate according to Mössbauer spectroscopy (MB). At that point the solution was removed from the glovebox and allowed to evaporate in the presence of atmospheric oxygen, leading to the oxidation of Fe2+. The evaporation rate was controlled by keeping the suspensions at different temperatures; pH was monitored during the evaporation process. The final precipitates were analyzed by MB and X-Ray Fluorescence (XRF), comparable to MER MB and Alpha Particle X-ray Spectrometer instrument datasets, and complementary techniques such as X

Olivine Major and Trace Element Compositions in Southern Payenia Basalts, Argentina

DEFF Research Database (Denmark)

Søager, Nina; Portnyagin, Maxim; Hoernle, Kaj

2015-01-01

Olivine major and trace element compositions from 12 basalts from the southern Payenia volcanic province in Argentina have been analyzed by electron microprobe and laser ablation inductively coupled plasma mass spectrometry. The olivines have high Fe/Mn and low Ca/Fe and many fall at the end of t...

RELICT OLIVINES IN MICROMETEORITES: PRECURSORS AND INTERACTIONS IN THE EARTH’S ATMOSPHERE

International Nuclear Information System (INIS)

Rudraswami, N. G.; Prasad, M. Shyam; Dey, S.; Fernandes, D.; Plane, J. M. C.; Feng, W.; Carrillo-Sánchez, J. D.; Taylor, S.

2016-01-01

Antarctica micrometeorites (∼1200) and cosmic spherules (∼5000) from deep sea sediments are studied using electron microscopy to identify Mg-rich olivine grains in order to determine the nature of the particle precursors. Mg-rich olivine (FeO < 5wt%) in micrometeorites suffers insignificant chemical modification during its history and is a well-preserved phase. We examine 420 forsterite grains enclosed in 162 micrometeorites of different types—unmelted, scoriaceous, and porphyritic—in this study. Forsterites in micrometeorites of different types are crystallized during their formation in solar nebula; their closest analogues are chondrule components of CV-type chondrites or volatile rich CM chondrites. The forsteritic olivines are suggested to have originated from a cluster of closely related carbonaceous asteroids that have Mg-rich olivines in the narrow range of CaO (0.1–0.3wt%), Al 2 O 3 (0.0–0.3wt%), MnO (0.0–0.3wt%), and Cr 2 O 3 (0.1–0.7wt%). Numerical simulations carried out with the Chemical Ablation Model (CABMOD) enable us to define the physical conditions of atmospheric entry that preserve the original compositions of the Mg-rich olivines in these particles. The chemical compositions of relict olivines affirm the role of heating at peak temperatures and the cooling rates of the micrometeorites. This modeling approach provides a foundation for understanding the ablation of the particles and the circumstances in which the relict grains tend to survive.

Comparative in situ X-ray Diffraction Study of San Carlos Olivine: Influence of Water on the 410 km Seismic Velocity Jump in Earth’s Mantle

Energy Technology Data Exchange (ETDEWEB)

J Chen; H Liu; J Girard

2011-12-31

A comparative study of the equation of states of hydrous (0.4 wt% H{sub 2}O) and anhydrous San Carlos olivine (<30 ppm H2O) was conducted using synchrotron X-rays up to 11 GPa in a diamond anvil cell (DAC) at ambient temperature. Both samples were loaded in the same high-pressure chamber of the DAC to eliminate the possible pressure difference in different experiments. The obtained compression data were fitted to the third-order Birch-Murnaghan equation of state, yielding a bulk modulus K{sub 0} = 123(3) GPa for hydrous olivine and K{sub 0} = 130(4) GPa for anhydrous olivine as K{sub 0}' is fixed at 4.6. Therefore, 0.4 wt% H{sub 2}2O in olivine results in a 5% reduction in bulk modulus. Previous studies reported bulk modulus reduction by water in olivine's high-pressure polymorph (wadsleyite), to which the transformation from olivine gives rise to the seismic discontinuity at 410 km depth. The new data results in a reduction in the magnitude of the discontinuity by 50% in v{sub P} and 30% in v{sub S} (for 1:5 water partitioning between olivine and wadsleyite) with respect to anhydrous mantle. Previous knowledge of the influence of water on this phase transition has been in opposition to a large amount of water [e.g., 200 ppm by Wood (1995)] existing at 410 km depth. Calculation of the seismic velocities based on newly available elasticity data of the hydrous phases indicates that the presence of water is favorable for the mineral composition model (pyrolite) and seismic observations in terms of the magnitude of the 410 km discontinuity.

Serpentinization and alteration in an olivine cumulate from the Stillwater Complex, Southwestern Montana

Science.gov (United States)

Page, N.J.

1976-01-01

Some of the olivine cumulates of the Ultramafic zone of the Stillwater Complex, Montana, are progressively altered to serpentine minerals and thompsonite. Lizardite and chrysotile developed in the cumulus olivine and postcumulus pyroxenes; thompsonite developed in postcumulus plagioclase. The detailed mineralogy, petrology, and chemistry indicate that olivine and plagioclase react to form the alteration products, except for H2O, without changes in the bulk composition of the rocks. ?? 1976 Springer-Verlag.

Synthesis and crystal structure of 4-fluorobenzylammonium dihydrogen phosphate, [FC6H4CH2NH3]H2PO4

Directory of Open Access Journals (Sweden)

Ali Rayes

2016-12-01

Full Text Available The asymmetric unit of the title salt, [p-FC6H4CH2NH3]+·H2PO4−, contains one 4-fluorobenzylammonium cation and one dihydrogen phosphate anion. In the crystal, the H2PO4− anions are linked by O—H...O hydrogen bonds to build corrugated layers extending parallel to the ab plane. The FC6H4CH2NH3+ cations lie between these anionic layers to maximize the electrostatic interactions and are linked to the H2PO4− anions through N—H...O hydrogen bonds, forming a three-dimensional supramolecular network. Two hydrogen atoms belonging to the dihydrogen phosphate anion are statistically occupied due to disorder along the OH...HO direction.

Steam reforming of bio-oil from coconut shell pyrolysis over Fe/olivine catalyst

International Nuclear Information System (INIS)

Quan, Cui; Xu, Shaoping; Zhou, Congcong

2017-01-01

Highlights: • Steam reforming of the actual bio-oil was investigated with Fe/olivine catalyst. • Most of phenols in bio-oil were converted into gas products. • A carbon conversion of 97.2% was obtained under optimized conditions. - Abstract: Catalytic steam reforming of coconut shell pyrolysis bio-oil over Fe/olivine catalyst was conducted in a fixed-bed quartz reactor. The effects of calcination temperature, iron loading, reaction temperature, steam to carbon ratio (S/C), bio-oil weight hourly space velocity (W b HSV) on gas composition and carbon conversion were investigated. The results indicate that Fe/olivine has good activity for steam reforming of bio-oil, the couple Fe 2+/3+ /Fe 2+ may be sufficiently efficient for C–C, C–O and C–H breaking. After steam reforming, most of the phenolics in pyrolysis oil are converted into light molecular compounds such as H 2 , CO, CO 2 , and CH 4 . The H 2 concentration and carbon conversion were enhanced by increasing reaction temperature from 750 to 800 °C and the S/C from 1.5 to 2, but decreased with increasing calcination temperature. In the W b HSV range of 0.5–0.6, the hydrogen concentration decreased obviously, whereas it decreased slightly by further increasing W b HSV. The highest hydrogen concentration of 47.6 vol% was obtained among the catalysts tested, and the best carbon conversion was 97.2% over 10% Fe/olivine catalyst under the reforming conditions of temperature = 800 °C, W b HSV = 0.5, S/C = 2.

Interaction of adsorption of reactive yellow 4 from aqueous solutions onto synthesized calcium phosphate

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H. El Boujaady

2017-01-01

Full Text Available The interaction of reactive yellow 4 with Apatitic Tricalcium Phosphate (PTCa has been investigated in aqueous medium to understand the mechanism of adsorption and explore the potentiality of this phosphate toward controlling pollution resulting from textile dyes. Transmission electron microscopy (TEM analysis demonstrates that the adsorbent is composed of needle-like nanoparticles and the SAED pattern exhibits spotted sharp and continuous rings that evidence polycrystalline grains. X-ray diffraction results showed that, the crystallinity of the dye decreased after interaction with RY4 indicatating incorporation of the dye into the micropores and macropores of the adsorbent. The results of Fourier transform infrared (FTIR spectroscopy indicate that the adsorption is due to the electrostatic interaction between the –SO3- groups of dye and the surface of the Phosphate. The desorption efficiency was very high at about 99.4%. The presence of calcium ions favored the adsorption of the dye, while the phosphate ions inhibited it.

Transport properties of olivine grain boundaries from electrical conductivity experiments

Science.gov (United States)

Pommier, Anne; Kohlstedt, David L.; Hansen, Lars N.; Mackwell, Stephen; Tasaka, Miki; Heidelbach, Florian; Leinenweber, Kurt

2018-05-01

Grain boundary processes contribute significantly to electronic and ionic transports in materials within Earth's interior. We report a novel experimental study of grain boundary conductivity in highly strained olivine aggregates that demonstrates the importance of misorientation angle between adjacent grains on aggregate transport properties. We performed electrical conductivity measurements of melt-free polycrystalline olivine (Fo90) samples that had been previously deformed at 1200 °C and 0.3 GPa to shear strains up to γ = 7.3. The electrical conductivity and anisotropy were measured at 2.8 GPa over the temperature range 700-1400 °C. We observed that (1) the electrical conductivity of samples with a small grain size (3-6 µm) and strong crystallographic preferred orientation produced by dynamic recrystallization during large-strain shear deformation is a factor of 10 or more larger than that measured on coarse-grained samples, (2) the sample deformed to the highest strain is the most conductive even though it does not have the smallest grain size, and (3) conductivity is up to a factor of 4 larger in the direction of shear than normal to the shear plane. Based on these results combined with electrical conductivity data for coarse-grained, polycrystalline olivine and for single crystals, we propose that the electrical conductivity of our fine-grained samples is dominated by grain boundary paths. In addition, the electrical anisotropy results from preferential alignment of higher-conductivity grain boundaries associated with the development of a strong crystallographic preferred orientation of the grains.

Synthesis of 4-substituted tetrahydropyridines by cross-coupling of enol phosphates

DEFF Research Database (Denmark)

Larsen, U.S.; Martiny, L.; Begtrup, M.

2005-01-01

Enol phosphates, synthesized from 4-piperidone, react by palladium catalyzed cross-coupling with arylboronic acids and by iron and palladium catalyzed cross-coupling with Grignard reagents to give 4-substituted tetrahydropyridines. (c) 2005 Elsevier Ltd. All rights reserved....

RELICT OLIVINES IN MICROMETEORITES: PRECURSORS AND INTERACTIONS IN THE EARTH’S ATMOSPHERE

Energy Technology Data Exchange (ETDEWEB)

Rudraswami, N. G.; Prasad, M. Shyam; Dey, S.; Fernandes, D. [National Institute of Oceanography (Council of Scientific and Industrial Research), Dona Paula, Goa 403004 (India); Plane, J. M. C.; Feng, W.; Carrillo-Sánchez, J. D. [School of Chemistry, University of Leeds, Leeds LS2 9JT (United Kingdom); Taylor, S., E-mail: rudra@nio.org [Cold Regions Research and Engineering Laboratory, 72 Lyme Road, Hanover, New Hampshire 03755-1290 (United States)

2016-11-10

Antarctica micrometeorites (∼1200) and cosmic spherules (∼5000) from deep sea sediments are studied using electron microscopy to identify Mg-rich olivine grains in order to determine the nature of the particle precursors. Mg-rich olivine (FeO < 5wt%) in micrometeorites suffers insignificant chemical modification during its history and is a well-preserved phase. We examine 420 forsterite grains enclosed in 162 micrometeorites of different types—unmelted, scoriaceous, and porphyritic—in this study. Forsterites in micrometeorites of different types are crystallized during their formation in solar nebula; their closest analogues are chondrule components of CV-type chondrites or volatile rich CM chondrites. The forsteritic olivines are suggested to have originated from a cluster of closely related carbonaceous asteroids that have Mg-rich olivines in the narrow range of CaO (0.1–0.3wt%), Al{sub 2}O{sub 3} (0.0–0.3wt%), MnO (0.0–0.3wt%), and Cr{sub 2}O{sub 3} (0.1–0.7wt%). Numerical simulations carried out with the Chemical Ablation Model (CABMOD) enable us to define the physical conditions of atmospheric entry that preserve the original compositions of the Mg-rich olivines in these particles. The chemical compositions of relict olivines affirm the role of heating at peak temperatures and the cooling rates of the micrometeorites. This modeling approach provides a foundation for understanding the ablation of the particles and the circumstances in which the relict grains tend to survive.

Meeting the Continental Crust: the Hidden Olivine Trauma in Subduction Settings

Science.gov (United States)

Salas Reyes, P.; Ruprecht, P.; Rabbia, O. M.; Hernandez, L.

2017-12-01

In a conventional framework, olivine zonation represents concentric growth from an evolving liquid. Alternatively, it has been suggested (e.g. Welsch et al. 2014) that olivine develop dendritic textures and compositional discontinuities due to rapid growth and boundary layer effects, respectively, where any complex zoning is quickly erased through diffusive re-equilibration in the high temperature magmatic environment. In particular, olivine crystals from large volcanic centers in convergent margins rarely preserve such dendritic textures and complex zoning due prolonged magma residence. Small volume, mafic monogenetic vents may bypass such crustal re-equilibration and potentially record the otherwise elusive early olivine growth history. We selected tephra deposits from Los Hornitos, in the Andean arc of Central Chile (35.5˚S), that represents primitive magmas ( 15 wt.% MgO) and contain magnesian olivines (Fo>88) hosting quenched melt inclusions. We obtained detailed quantitative EPMA zoning profiles and measured volatile contents (H, C, S, Cl) in the co-existing melt inclusions. Furthermore, we analyzed mineral morphologies connecting compositional zoning with growth textures. We find that 40% of the olivine crystals retain dendritic shapes while the others are polyhedral with trapped melt inclusions and cavities. The polyhedral crystals are normally zoned (Fo92 to Fo88; Ni 4000 ppm to 1000 ppm), however an oscillatory zonation depicted by concentric -coupled Fo and Ni- enriched layers exist and therefore even those crystals still preserve also a more complete growth history. The related melt inclusions yield values of up to 6000 ppm of S. Such zonation may imply sudden growth during elevated degrees of undercooling (-ΔT > 60°C) as the magmas transit from the hot mantle to the cooler conditions in the crust. Moreover, the preservation of such Fo and Ni zonation requires limited time between crystal growth and eruption. The elevated S content in melt inclusions

Low temperature dissolution creep induced B-type olivine fabric during serpentinization and deformation in mantle wedge

Science.gov (United States)

Liu, W.; Zhang, J.

2017-12-01

The B-type olivine fabric (i.e., the [010]ol axes subnormal to foliation and the [001]ol axes subparallel to the lineation) has been regarded as an important olivine fabric for interpreting global trench-parallel S-wave polarization in fore-arc regions. However, strong serpentinization and cold temperature environment in the mantle wedge should inhibit development of the B-type olivine fabric that requires high temperature to activate solid-state plastic deformation. Here we report fabrics of olivine and antigorite generated at low temperatures (300-370 oC) during serpentinization in a fossil mantle wedge of the Val Malenco area, Central Alps. Olivine in the serpentine matrix develops a pronounced B-type fabric, while antigorite in the same matrix displays a strong crystallographic orientation (CPO) with the (001) and the [010] subparallel to foliation and lineation, respectively. The following evidence leads to the conclusion that the B-type olivine fabric is resulted from dissolution creep assisted by grain boundaries sliding (GBS) and grain rotation, rather than solid-state plastic deformation: (1) serpentinization took place at low temperatures and a fluid-enriched environment, ideal for dissolution-precipitation creep; (2) the voids and zigzag boundaries along the interface between antigorite and olivine suggest a fluid dissolution reaction; (3) the primary coarse olivine develops a nearly random fabric, indicating the B-type fabrics in the fine-grained olivine can't be inherited fabrics. These results document for the first time the B-type olivine CPO formed by dissolution creep at low temperatures during serpentinization and provide a mechanism to reconcile petrofabric observations with geophysical observations of trench parallel fast S-wave seismic anisotropy in fore-arc mantle wedge regions.

Temperature dependence of sulfide and sulfate solubility in olivine-saturated basaltic magmas

Science.gov (United States)

Beermann, O.; Botcharnikov, R. E.; Holtz, F.; Diedrich, O.; Nowak, M.

2011-12-01

The sulfur concentration at pyrrhotite- and anhydrite-saturation in primitive hydrous basaltic melt of the 2001-2002 eruption of Mt. Etna was determined at 200 MPa, T = 1050-1250 °C and at log fO 2 from FMQ to FMQ+2.2 (FMQ is Fayalite-Magnetite-Quartz oxygen buffer). At 1050 °C Au sample containers were used. A double-capsule technique, using a single crystal olivine sample container closed with an olivine piston, embedded in a sealed Au 80Pd 20 capsule, was developed to perform experiments in S-bearing hydrous basaltic systems at T > 1050 °C. Pyrrhotite is found to be a stable phase coexisting with melt at FMQ-FMQ+0.3, whereas anhydrite is stable at FMQ+1.4-FMQ+2.2. The S concentration in the melt increases almost linearly from 0.12 ± 0.01 to 0.39 ± 0.02 wt.% S at FeS-saturation and from 0.74 ± 0.01 to 1.08 ± 0.04 wt.% S at anhydrite-saturation with T ranging from 1050-1250 °C. The relationships between S concentration at pyrrhotite and/or anhydrite saturation, MgO content of the olivine-saturated melt, T, and log fO 2 observed in this study and from previous data are used to develop an empirical model for estimating the magmatic T and fO 2 from the S and MgO concentrations of H 2O-bearing olivine-saturated basaltic melts. The model can also be used to determine maximum S concentrations, if fO 2 and MgO content of the melt are known. The application of the model to compositions of melt inclusions in olivines from Mt. Etna indicates that the most primitive magmas trapped in inclusions might have been stored at log fO 2 slightly higher than FMQ+1 and at T = 1100-1150 °C, whereas more evolved melts could have been trapped at T ⩽ 1100 °C. These values are in a good agreement with the estimates obtained by other independent methods reported in the literature.

Correlations Between Olivine Abundance and Thermal Inertia: Implications for Global Weathering and/or Alteration on Mars

Science.gov (United States)

Hamilton, V. E.; McDowell, M. L.; Koeppen, W. C.

2010-03-01

TES data show no global trend between thermal inertia and olivine abundance. But it is premature to conclude that all dark surfaces were once more mafic OR that olivine is not preferentially removed from olivine-enriched outcrops as they erode.

Limitations on the Estimation of Parental Magma Temperature Using Olivine-melt Equilibria: Hotspots Not So Hot

Science.gov (United States)

Natland, J. H.

2004-12-01

Estimates of temperatures of magmas parental to picritic tholeiites using olivine-melt equilibria and FeO-MgO relationships depend strongly on the assumption that a liquid composition, usually a glass, is related to the most magnesian olivine in the rock, or to an olivine composition in equilibrium with mantle peridotite, along an olivine-controlled liquid line of descent. The liquid Fe2+/Fe3+ also has to be known; where data exist, average values from wet chemical determinations are used. Crystallization histories of tholeiitic picrites from islands, spreading ridges, and large igneous provinces, however, usually reveal them to be hybrid rocks that are assembled by two types of magma mixing: 1) between a) differentiated magmas that are on olivine-plagioclase or olivine-plagioclase-clinopyroxene cotectics and b) crystal sludges with abundant olivine that may have accumulated from liquids crystallizing olivine alone; and 2) between primitive magma strains in which olivine crystallized either alone or with other silicate minerals at elevated pressure on separate liquid lines of descent. Many picrites give evidence that both types of mixing have occurred. If either type has occurred, the assumption of olivine-control linking a glass and an olivine composition can only circumstantially be correct. Oxidation state can also be underestimated and therefore FeO contents overestimated if basalts have degassed S, as at Hawaii. In Case 1, hybrid host glass compositions often have higher FeO at given MgO content than liquids which produced many olivine crystals in the rock. In Case 2, the separate parental melt strains are revealed by diversity of compositions of both melt inclusions and Cr-spinel and are most often interpreted to mean local heterogeneity of the mantle source. The inclusions do not always affirm an olivine-controlled liquid line of descent. Instead, inclusions with Gorgona, but not in MORB. Where fresh glass is lacking (e.g., Gorgona), bulk-rock compositions

Overexpression, crystallization and preliminary X-ray crystallographic analysis of erythronate-4-phosphate dehydrogenase from Pseudomonas aeruginosa

Energy Technology Data Exchange (ETDEWEB)

Ha, Jun Yong; Lee, Ji Hyun; Kim, Kyoung Hoon; Kim, Do Jin; Lee, Hyung Ho; Kim, Hye-Kyung; Yoon, Hye-Jin; Suh, Se Won, E-mail: sewonsuh@snu.ac.kr [Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of)

2006-02-01

Erythronate-4-phosphate dehydrogenase from P. aeruginosa was crystallized and X-ray diffraction data were collected to 2.20 Å resolution. The enzyme erythronate-4-phosphate dehydrogenase catalyses the conversion of erythronate-4-phosphate to 3-hydroxy-4-phospho-hydroxy-α-ketobutyrate. It belongs to the d-isomer-specific 2-hydroxyacid dehydrogenase family. It is essential for de novo biosynthesis of vitamin B{sub 6} (pyridoxine). Erythronate-4-phosphate dehydrogenase from Pseudomonas aeruginosa, a homodimeric enzyme consisting of two identical 380-residue subunits, has been overexpressed in Escherichia coli with a C-terminal purification tag and crystallized at 297 K using 0.7 M ammonium dihydrogen phosphate, 0.4 M ammonium tartrate, 0.1 M sodium citrate pH 5.6 and 10 mM cupric chloride. X-ray diffraction data were collected to 2.20 Å from a crystal grown in the presence of NADH. The crystals belong to the orthorhombic space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 84.77, b = 101.28, c = 142.58 Å. A dimeric molecule is present in the asymmetric unit, giving a crystal volume per protein weight (V{sub M}) of 3.64 Å{sup 3} Da{sup −1} and a solvent content of 66%.

Overexpression, crystallization and preliminary X-ray crystallographic analysis of erythronate-4-phosphate dehydrogenase from Pseudomonas aeruginosa

International Nuclear Information System (INIS)

Ha, Jun Yong; Lee, Ji Hyun; Kim, Kyoung Hoon; Kim, Do Jin; Lee, Hyung Ho; Kim, Hye-Kyung; Yoon, Hye-Jin; Suh, Se Won

2006-01-01

Erythronate-4-phosphate dehydrogenase from P. aeruginosa was crystallized and X-ray diffraction data were collected to 2.20 Å resolution. The enzyme erythronate-4-phosphate dehydrogenase catalyses the conversion of erythronate-4-phosphate to 3-hydroxy-4-phospho-hydroxy-α-ketobutyrate. It belongs to the d-isomer-specific 2-hydroxyacid dehydrogenase family. It is essential for de novo biosynthesis of vitamin B 6 (pyridoxine). Erythronate-4-phosphate dehydrogenase from Pseudomonas aeruginosa, a homodimeric enzyme consisting of two identical 380-residue subunits, has been overexpressed in Escherichia coli with a C-terminal purification tag and crystallized at 297 K using 0.7 M ammonium dihydrogen phosphate, 0.4 M ammonium tartrate, 0.1 M sodium citrate pH 5.6 and 10 mM cupric chloride. X-ray diffraction data were collected to 2.20 Å from a crystal grown in the presence of NADH. The crystals belong to the orthorhombic space group P2 1 2 1 2 1 , with unit-cell parameters a = 84.77, b = 101.28, c = 142.58 Å. A dimeric molecule is present in the asymmetric unit, giving a crystal volume per protein weight (V M ) of 3.64 Å 3 Da −1 and a solvent content of 66%

Dehydration breakdown of antigorite and the formation of B-type olivine CPO

Science.gov (United States)

Nagaya, Takayoshi; Wallis, Simon R.; Kobayashi, Hiroaki; Michibayashi, Katsuyoshi; Mizukami, Tomoyuki; Seto, Yusuke; Miyake, Akira; Matsumoto, Megumi

2014-02-01

Peridotite formed by contact metamorphism and dehydration breakdown of an antigorite schist from the Happo area, central Japan shows a strong olivine crystallographic preferred orientation (Ol CPO). The lack of mesoscale deformation structures associated with the intrusion and the lack of microstructural evidence for plastic deformation of neoblastic grains suggest that olivine CPO in this area did not form as a result of solid-state deformation. Instead, the good correspondence between the original antigorite orientation and the orientation of the newly formed olivine implies the CPO formed by topotactic growth of the olivine after antigorite. Ol CPO is likely to develop by a similar process in subduction zone environments where foliated serpentinite is dragged down to depths where antigorite is no longer stable. The Happo Ol CPO has a strong a-axis concentration perpendicular to the lineation and within the foliation-commonly referred to as B-type Ol CPO. Seismic fast directions parallel to the ocean trench are observed in many convergent margins and are consistent with the presence of B-type Ol CPO in the mantle wedge of these regions. Experimental work has shown that B-type CPO can form by dislocation creep under hydrous conditions at relatively high stresses. There are, however, several discrepancies between the characteristics of natural and laboratory samples with B-type Ol CPO. (1) The formation conditions (stress and temperature) of some natural examples with B-type CPO fall outside those predicted by experiments. (2) In deformation experiments, slip in the crystallographic c-axis direction is important but has not been observed in natural examples of B-type CPO. (3) Experimental work suggests the presence of H2O and either high shear stress or relatively low temperatures are essential for the formation of B-type CPO. These conditions are most likely to be achieved close to subduction boundaries, but these regions are also associated with serpentinization

Preliminary quantification of a shape model for etch-pits formed during natural weathering of olivine

International Nuclear Information System (INIS)

Nowicki, M. Anna; Velbel, Michael A.

2011-01-01

Many etch-pits on olivine grains occur as a pair of cone-shaped pits sharing a base, which consequently appear as diamond-shaped etch-pits in cross-section. Quantitative image analysis of back-scattered electron images establishes empirical dimensions of olivine etch-pits in naturally weathered samples from Hawaii and North Carolina. Images of naturally etched olivine were acquired from polished thin-sections by scanning electron microscopy. An average cone-radius-to-height ratio (r:h) of 1.78 was determined for diamond-shaped cross-sections of etch-pits occurring in naturally weathered olivine grains, largely consistent with previous qualitative results. Olivine etch-pit shape as represented by r:h varies from slightly more than half the average value to slightly more than twice the average. Etch-pit shape does not appear to vary systematically with etch-pit size.

Traces of heavy and superheavy cosmic nuclei in olivins of extraterrestial origin

International Nuclear Information System (INIS)

Ignatova, R.; Taneva, T.

1982-01-01

The paths of traces of WH nuclei from cosmic rays have been measured in olivines from the meteorites Maryalakhti, Eagle Stein, Liposki khutor with radiation ages 175, 45 and 220 million years respectively. 3 cm 3 olivines of these meteorites have been examined and more than 500 traces of nuclei with Z(>=)90 have been found measured including 3 traces 1.5-1.8 times longer than the traces created by the uranium and thorium nuclei. These traces may be left by nuclei with Z(>=)110. The crystals were chosen from localizations situated at 2-7 cm, 8-9 cm and 10-12 cm from the outside atmospheric surface of the meteorite. The abundancy of the Z(>=)50 nuclei in gigantic cosmic rays, averaged for a period of ( =)110 in galactic cosmic rays. It is 1.4 x 10 -9 from that of the iron group nuclei. (authors)

Olivine Dissolution in Seawater: Implications for CO2 Sequestration through Enhanced Weathering in Coastal Environments

Science.gov (United States)

2017-01-01

Enhanced weathering of (ultra)basic silicate rocks such as olivine-rich dunite has been proposed as a large-scale climate engineering approach. When implemented in coastal environments, olivine weathering is expected to increase seawater alkalinity, thus resulting in additional CO2 uptake from the atmosphere. However, the mechanisms of marine olivine weathering and its effect on seawater–carbonate chemistry remain poorly understood. Here, we present results from batch reaction experiments, in which forsteritic olivine was subjected to rotational agitation in different seawater media for periods of days to months. Olivine dissolution caused a significant increase in alkalinity of the seawater with a consequent DIC increase due to CO2 invasion, thus confirming viability of the basic concept of enhanced silicate weathering. However, our experiments also identified several important challenges with respect to the detailed quantification of the CO2 sequestration efficiency under field conditions, which include nonstoichiometric dissolution, potential pore water saturation in the seabed, and the potential occurrence of secondary reactions. Before enhanced weathering of olivine in coastal environments can be considered an option for realizing negative CO2 emissions for climate mitigation purposes, these aspects need further experimental assessment. PMID:28281750

B-type olivine fabric induced by low temperature dissolution creep during serpentinization and deformation in mantle wedge

Science.gov (United States)

Liu, Wenlong; Zhang, Junfeng; Barou, Fabrice

2018-01-01

The B-type olivine fabric (i.e., the [010] axes subnormal to foliation and the [001] axes subparallel to the lineation) has been regarded as an important olivine fabric for interpreting global trench-parallel S-wave polarization in fore-arc regions. However, strong serpentinization and cold temperature environment in the mantle wedge should inhibit development of the B-type olivine fabric that requires high temperature to activate solid-state plastic deformation. Here we report fabrics of olivine and antigorite generated at low temperatures (300-370 °C) during serpentinization in a fossil mantle wedge of the Val Malenco area, Central Alps. Olivine in the serpentine matrix develops a pronounced B-type fabric, while antigorite in the same matrix displays a strong crystallographic preferred orientation (CPO) with the (001) planes and the [010] axes subparallel to foliation and lineation, respectively. The following evidence leads to the conclusion that the B-type olivine fabric results from dissolution creep assisted by grain boundary sliding (GBS) and grain rotation, rather than solid-state plastic deformation: (1) serpentinization took place at low temperatures and a fluid-enriched environment, ideal for dissolution-precipitation creep; (2) the voids and zigzag boundaries along the interface between antigorite and olivine suggest a fluid dissolution reaction; (3) the primary coarse olivine develops a nearly random fabric, indicating the B-type fabrics in the fine-grained olivine may not be inherited fabrics. These results document for the first time the B-type olivine CPO formed by dissolution creep at low temperatures during serpentinization and provide a mechanism to reconcile petrofabric observations with geophysical observations of trench parallel fast S-wave seismic anisotropy in fore-arc mantle wedge regions.

A Tale of Two Olivines: Magma Ascent in the Auckland Volcanic Field, New Zealand

Science.gov (United States)

Smid, E. R.; McGee, L. E.; Smith, I. E.; Lindsay, J. M.

2013-12-01

The Auckland Volcanic Field (AVF) is a nephelinitic to subalkali basaltic monogenetic field centered on the city of Auckland, New Zealand. Lavas are olivine-phyric, and the deposits of several volcanoes in the field contain olivine crystals with chrome spinel (Cr-spinel) inclusions. Microprobe analyses show at least two populations of olivine, categorised by their Mg# and their spinel inclusion compositions: the first has olivines that are euhedral, have compositions slightly less forsteritic than expected for whole rock Mg#, and have Cr-spinel inclusions with relatively low Cr2O3 contents of ~20%. These are interpreted as antecrysts inherited from the mantle source that yielded their host magma. The second population is characterised by olivines that are sub- to euhedral, are significantly more forsteritic than expected from their host whole rock Mg#, and have Cr-spinel inclusons with relatively high Cr2O3 contents of ~50%. These are interpreted as xenocrysts. The composition of these high Cr2O3 spinels very closely resembles the composition of spinels within olivines in dunite sampled from the Dun Mountain Ophiolite on the South Island of New Zealand. The northward extension of the Dun Mountain complex beneath the North Island is defined by the Junction Magnetic Anomaly, marking a crustal terrane boundary that underlies the Auckland Volcanic Field. These data indicate that the magmas that have risen to produce the volcanoes of the Auckland Volcanic Field have carried crystals from an underlying ultramafic crust as well as from their asthenospheric source. Euhedral olivine crystals which do not contain Cr-spinel are also present in AVF lavas and these are interpreted as true phenocrysts that crystallised directly from their host magmas. The lack of reaction textures at crystal margins suggests rapid ascent rates. A crustal origin for the xenocrysts not only has large implications for ascent rate modelling of olivines, but also for the crustal structure of the

Vanadium K XANES of synthetic olivine: Valence determinations and crystal orientation effects

International Nuclear Information System (INIS)

Sutton, S.R.; Newville, M.

2005-01-01

Vanadium can exist in a large number of valence states in nature (2+?, 3+, 4+ and 5+) and determinations of V valence is therefore valuable in defining the oxidation states of earth and planetary materials over a large redox range. Synchrotron-based x-ray absorption near edge structure (XANES) spectroscopy is well-suited for measurements of V valence with ∼micrometer spatial resolution and ∼ppm elemental sensitivity. Applications of microXANES have been demonstrated for basaltic glasses. Applications to minerals are feasible but complicated by orientation effects (e.g. due to polarization of the synchrotron x-ray beam) and some results for spinel have been reported. Here we report initial results for olivine from laboratory crystallization ex-periments. The goal is to define the valence partition-ing between olivine and melt and quantify the magnitude of orientation effects, the latter tested by measuring grains at a variety of orientations in the same charge.

Overexpression, crystallization and preliminary X-ray crystallographic analysis of erythronate-4-phosphate dehydrogenase from Pseudomonas aeruginosa.

Science.gov (United States)

Ha, Jun Yong; Lee, Ji Hyun; Kim, Kyoung Hoon; Kim, Do Jin; Lee, Hyung Ho; Kim, Hye-Kyung; Yoon, Hye-Jin; Suh, Se Won

2006-02-01

The enzyme erythronate-4-phosphate dehydrogenase catalyses the conversion of erythronate-4-phosphate to 3-hydroxy-4-phospho-hydroxy-alpha-ketobutyrate. It belongs to the D-isomer-specific 2-hydroxyacid dehydrogenase family. It is essential for de novo biosynthesis of vitamin B6 (pyridoxine). Erythronate-4-phosphate dehydrogenase from Pseudomonas aeruginosa, a homodimeric enzyme consisting of two identical 380-residue subunits, has been overexpressed in Escherichia coli with a C-terminal purification tag and crystallized at 297 K using 0.7 M ammonium dihydrogen phosphate, 0.4 M ammonium tartrate, 0.1 M sodium citrate pH 5.6 and 10 mM cupric chloride. X-ray diffraction data were collected to 2.20 A from a crystal grown in the presence of NADH. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 84.77, b = 101.28, c = 142.58 A. A dimeric molecule is present in the asymmetric unit, giving a crystal volume per protein weight (VM) of 3.64 A3 Da(-1) and a solvent content of 66%.

Some properties of tetravalent actinide phosphates of M1M42(PO4)3 type and peculiarities of their structure

International Nuclear Information System (INIS)

Burnaeva, A.A.; Volkov, Yu.F.; Kryukova, A.I.; Skiba, O.V.; Spiryakov, V.I.; Korshunov, I.A.; Samojlova, T.K.

1987-01-01

Generalizing analysis of data on crystallographic and IR spectral properties of double phosphates of actinide and alkali elements of M (1) M 2 (4) (PO 4 ) 3 type is conducted. It is shown, that Li - , Na - , K - , Rb - , CsTh 2 (PO 4 ) 3 , Li - , Na - , KU 2 (PO 4 ) 3 , NaNp 2 (PO 4 ) 3 compounds crystallize in a monoclinic type structure and form an isostructural phosphate series. It is ascertained, that in rubidium-uranium, uranium-cesium systems double salt formation is not observed. Plutonium-sodium phosphate has a rhombic-type structure, which points out to the existence of a morphotropic transition in NaM 2 4 (PO 4 ) 3 phosphate series at the Np-Pu boundary. Some regularities of structure and effect of M 1 and M 4 nature on the double phosphate structure are revealed

Investigations on the passivity of iron in borate and phosphate buffers, pH 8.4

International Nuclear Information System (INIS)

Sieber, I.V.; Hildebrand, H.; Virtanen, S.; Schmuki, P.

2006-01-01

In the present work surface analytical experiments (XPS and AES) on the passive film on iron formed in borate and phosphate buffers (pH 8.4) have been carried out. In the passive film formed in phosphate buffer a significant amount of phosphates is found in the outer part of the film. Boron species are not significantly incorporated in the passive film formed in borate buffer. The mechanism of the reduction of the passive film depends strongly on the electrolyte composition. In borate buffer, cathodic polarization leads to reductive dissolution of the passive film whereas in phosphate buffer the passive film is converted into metallic iron without dissolution but via laterally inhomogeneously formation of an intermediate Fe(II) phosphate layer

Structure-based prediction and identification of 4-epimerization activity of phosphate sugars in class II aldolases.

Science.gov (United States)

Lee, Seon-Hwa; Hong, Seung-Hye; An, Jung-Ung; Kim, Kyoung-Rok; Kim, Dong-Eun; Kang, Lin-Woo; Oh, Deok-Kun

2017-05-16

Sugar 4-epimerization reactions are important for the production of rare sugars and their derivatives, which have various potential industrial applications. For example, the production of tagatose, a functional sweetener, from fructose by sugar 4-epimerization is currently constrained because a fructose 4-epimerase does not exist in nature. We found that class II D-fructose-1,6-bisphosphate aldolase (FbaA) catalyzed the 4-epimerization of D-fructose-6-phosphate (F6P) to D-tagatose-6-phosphate (T6P) based on the prediction via structural comparisons with epimerase and molecular docking and the identification of the condensed products of C3 sugars. In vivo, the 4-epimerization activity of FbaA is normally repressed. This can be explained by our results showing the catalytic efficiency of D-fructose-6-phosphate kinase for F6P phosphorylation was significantly higher than that of FbaA for F6P epimerization. Here, we identified the epimerization reactions and the responsible catalytic residues through observation of the reactions of FbaA and L-rhamnulose-1-phosphate aldolases (RhaD) variants with substituted catalytic residues using different substrates. Moreover, we obtained detailed potential epimerization reaction mechanism of FbaA and a general epimerization mechanism of the class II aldolases L-fuculose-1-phosphate aldolase, RhaD, and FbaA. Thus, class II aldolases can be used as 4-epimerases for the stereo-selective synthesis of valuable carbohydrates.

Uptake of CrO{sub 4}{sup 2-} ions by Fe-treated tri-calcium phosphate

Energy Technology Data Exchange (ETDEWEB)

Serrano G, J.; Ramirez S, J. L.; Bonifacio M, J.; Granados C, F.; Badillo A, V. E., E-mail: juan.serrano@inin.gob.m [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

2010-07-01

CrO{sub 4}{sup 2-} ion adsorption of Fe-treated tri-calcium phosphate was studied by batch experiments as a function of contact time, initial concentration of metal ion and temperature. Adsorption results showed that at ph 5.5 and 1.0 x 10{sup -4} M chromium concentration the adsorption capacity of Fe-treated tri-calcium phosphate for CrO{sub 4}{sup 2-} ions was 7.10 x 10{sup -3} mmol/g. Chromium adsorption data on Fe-treated tri-calcium phosphate at various initial concentration fitted the Freundlich isotherm. By temperature studies the thermodynamic parameters {Delta}H{sup 0}, {Delta}G{sup 0} and {Delta}S{sup 0} were estimated and the obtained results showed that the adsorption reaction was endothermic and spontaneous. (Author)

Thermodynamics of the hydrolysis reactions of α-D-galactose 1-phosphate, sn-glycerol 3-phosphate, 4-nitrophenyl phosphate, phosphocreatine, and 3-phospho-D-glycerate

International Nuclear Information System (INIS)

Goldberg, Robert N.; Lang, Brian E.; Lo, Catherine; Ross, David J.; Tewari, Yadu B.

2009-01-01

Microcalorimetry, high-performance liquid chromatography (h.p.l.c.), and an enzymatic assay have been used to conduct a thermodynamic investigation of five phosphate hydrolysis reactions: {α-D-galactose 1-phosphate(aq) + H 2 O(l) = D-galactose(aq) + orthophosphate(aq)} (1), {sn-glycerol 3-phosphate(aq) + H 2 O(l) = glycerol(aq) + orthophosphate(aq)} (2), {4-nitrophenyl phosphate(aq) + H 2 O(l) = 4-nitrophenol(aq) + orthophosphate(aq)} (3), {phosphocreatine(aq) + H 2 O(l) = creatine(aq) + orthophosphate(aq)} (4), and {3-phospho-D-glycerate(aq) + H 2 O(l) = D-glycerate(aq) + orthophosphate(aq)} (5). Calorimetrically determined enthalpies of reaction Δ r H(cal) were measured for reactions (1)-(5) and the apparent equilibrium constant K' was measured for reaction (2). The pKs and standard enthalpies of reaction Δ r H 0 for the H + and Mg 2+ binding reactions of the reactants and products in the aforementioned reactions were obtained either from the literature or by estimation. A chemical equilibrium model was then used to calculate standard equilibrium constants K and standard enthalpies of reaction Δ r H 0 for chemical reference reactions that correspond to the overall biochemical reactions that were studied experimentally. Property values from the literature and thermodynamic network calculations were used to obtain values of the equilibrium constants for the chemical reference reactions that correspond to the overall biochemical reactions (1). These values were compared with other results from the literature and also correlated with structural features. The results obtained in this study can be used in the chemical equilibrium model to calculate values of K', the standard apparent Gibbs free energy changes Δ r G '0 , the standard apparent enthalpy changes Δ r H '0 , changes in binding of the proton Δ r N(H + ), and the position of equilibrium for the overall biochemical reactions considered in this study over a reasonably wide range of temperature, pH, p

Phosphate removal from aqueous solutions using polyaniline/ Ni 0.5 Zn 0.5 Fe 2 O 4 magnetic nanocomposite

Directory of Open Access Journals (Sweden)

Mohammad Hossein Tarmahi

2017-05-01

Full Text Available Background: Phosphorus is an indispensable element for the growth of animals and plants. There are several environmental problems related to phosphate; therefore, the technical and economic methods of removing phosphate are of great importance. This study evaluated the efficiency of polyaniline/ Ni0.5Zn0.5Fe2O4 magnetic nanocomposite in removing phosphate from aqueous environments. Methods: The adsorbent was characterized by several methods, including X-ray diffraction (XRD, scanning electron microscopy (SEM, vibrating sample magnetometer (VSM, and Fourier transform infrared (FT-IR spectroscopy. Then, the potential of the adsorbentto adsorb phosphate was investigated. The effects of the parameters of contact time (5-60 minutes, pH (3-9, adsorbent dosage (0.05-0.6 g, and initial phosphate concentration (2-100 mg/L on the phosphate removal yield were studied. All phosphate ion concentrations were measured using the ammonium molybdate spectrophotometric method. Results: The results showed that a time of 30 minutes, pH of 5, and adsorbent dose of 0.4 g were the optimum conditions for phosphate removal through adsorption. Increasing the initial concentration of phosphate from 2 to 100 mg/L decreased the removal efficiency from 90.3% to 32%. The experimental data was fitted well with the Freundlich isotherm model (R2 = 0.997. Conclusion: Polyaniline/Ni0.5Zn0.5Fe2O4 magnetic nanocomposite removes phosphate from aqueous solutions with a simple and environmentally benign procedure. The maximum adsorption capacity based on Langmuir isotherm (R2 = 0.931 is 85.4 mg/g. This magnetic nanocomposite is applicable in managing water resource pollution caused by phosphate ions.

Rocks Whose Compositions are Determined by Flow Differentiation of Olivine- and Sulfide Droplet-Laden Magma: the Jinchuan Story

Science.gov (United States)

Li, C.; Ripley, E. M.; de Waal, S. A.; Xu, Z.

2002-12-01

The Jinchuan intrusion in western China is an elongated, deeply-dipping dyke-like body of dominantly olivine-rich ultramafic rocks of high magnesium basaltic magma. It hosts the second largest Ni-Cu sulfide deposit in the world. More than 500 million tones of sulfide ore grading 1.2 percent Ni and 0.7 percent Cu occur mostly as next-textured and disseminated sulfide (pyrrhotite, pentlendite and chalcopyrite) with cumulus olivine in about half of the rocks of the intrusion. Based on different petrological zonations, the Jinchuan intrusion is further divided into three segments: eastern, central and western segments. The central segment is characterized by concentric enrichments of cumulus olivine and sulfide, whereas the eastern and western segments are characterized by the increase of both cumulus olivine and sulfide toward the footwall. The forsterite contents of fresh olivine from different segments are similar and vary between 82 and 86 mole percent. The small range of olivine compositional variation corresponds to less than 6 percent of fractional crystallization. Mass balance calculations based on sulfide solubility in basaltic magma indicate that the volume of the parental magma of the sulfide is many times larger than that which is currently represented in the intrusion. Large amounts of cumulus olivine (more than 40 weight percent) in the marginal samples and high concentrations of sulfide in the intrusion are consistent with an interpretation that the Jinchuan intrusion was formed by olivine- and sulfide droplet-laden magma ascending through a subvertical conduit to a higher level. Differentiation processes of the olivine- and sulfide droplet-laden magma varied in different parts of the conduit. Sub-vertical flow differentiation controlled the central segment of the conduit, resulting in further enrichment of olivine crystals and sulfide droplets in the conduit center. In contrast, sub-lateral flow and gravitational differentiation dominated in the eastern

Production and Application of Olivine Nano-Silica in Concrete

Science.gov (United States)

Mardiana, Oesman; Haryadi

2017-05-01

The aim of this research was to produce nano silica by synthesis of nano silica through extraction and dissolution of ground olivine rock, and applied the nano silica in the design concrete mix. The producing process of amorphous silica used sulfuric acid as the dissolution reagent. The separation of ground olivine rock occurred when the rock was heated in a batch reactor containing sulfuric acid. The results showed that the optimum mole ratio of olivine- acid was 1: 8 wherein the weight ratio of the highest nano silica generated. The heating temperature and acid concentration influenced the mass of silica produced, that was at temperature of 90 °C and 3 M acid giving the highest yield of 44.90%. Characterization using Fourier Transform Infrared (FTIR ) concluded that amorphous silica at a wavenumber of 1089 cm-1 indicated the presence of siloxane, Si-O-Si, stretching bond. Characterization using Scanning Electron Microscope - Energy Dispersive Spectroscopy (SEM-EDS) showed the surface and the size of the silica particles. The average size of silica particles was between 1-10 μm due to the rapid aggregation of the growing particles of nano silica into microparticles, caused of the pH control was not fully achieved.

Mixed phosphates of the Na3PO4 - LnPO4 systems

International Nuclear Information System (INIS)

Slivko, T.A.; Smirnova, I.N.; Zimina, G.V.; Spiridonov, F.M.; Chudinova, N.N.

2002-01-01

The phase relationships in the systems Na 3 PO 4 - LnPO 4 (subsolidus 950 Deg C cross-sections), where Ln=Sm, Eu, Tb, Dy, Ho, Tm, Yb, Lu, were studied by X-ray analysis. Reactions of the components were deduced, formed phases were separated and identified. The Na 6 Ln 3 (PO 4 ) 5 (Ln=Dy, Ho, Tm), Na 3 Ln 2 (PO 4 ) 3 (Ln=Tm, Yb, Lu) compounds and phases of the unstable composition Na 6+x Ln 3-x/3 (PO 4 ) 5 (Ln=Yb, Lu, 0 ≤ x ≤ 1.5) were detected for the first time. In all systems the existence of the Na 3-x Ln x/3 PO 4 unstable composition phase on the basis of the high temperature modification of sodium phosphate (sp. gr. Fm3m) is established, suggesting that stabilization of this modification by rare earth ions is possible [ru

Optimization of Liquid Medium for High Phosphate Solubilization by Serratia Marcescens Strain AGKT4

Directory of Open Access Journals (Sweden)

Mohd Yusoff Abd. Samad

2017-12-01

Full Text Available This study is on the optimization of the medium for solubilization of phosphate based on the Box-Behnken design and response surface methodology. Optimization of the liquid medium for phosphate solubilization using Serratia marcescens strain AGKT4 was carried out by varying the concentrations of 3 ingredients; the fructose, peptone and inoculum size of bacteria. A mathematical model derived from the response surface methodology was then validated statistically for the target test variables. The highest phosphate solubilization in the medium was achieved at the optimal concentrations of fructose and peptone at 6% (w/v and 0.6% (w/v, respectively. The maximum phosphate solubilization at these concentrations was 239.12 µg/mL. Under the same conditions, the bacterial growth in the medium was 9 log10 CFU.

Catalytic reforming of toluene as tar model compound: effect of Ce and Ce-Mg promoter using Ni/olivine catalyst.

Science.gov (United States)

Zhang, Ruiqin; Wang, Huajian; Hou, Xiaoxue

2014-02-01

Tar produced by biomass gasification as a route of renewable energy must be removed before the gas can be used. This study was undertaken using toluene as a model tar compound for evaluating its steam reforming conversion with three Ni-based catalysts, Ni/olivine, Ni-Ce/olivine and Ni-Ce-Mg/olivine. Effects of Ce and Mg promoters on the reaction activity and coke deposition were studied. Overall the performance of Ce and Mg promoted Ni/olivine catalysts is better than that of only Ce promoter and Ni/olivine alone. The experimental results indicate that Ni-Ce-Mg/olivine catalysts could improve the resistance to carbon deposition, enhance energy gases yield and resist 10ppm H2S poison at 100mLmin(-1) for up to 400min. Furthermore, the activity of catalysts was related to the steam/carbon (S/C) ratios; at S/C ratio=5, T=790°C, space velocity=782h(-1) and t=2h, the Ni-Ce-Mg/olivine system yielded 89% toluene conversion, 5.6Lh(-1) product gas rate, 62.6mol% H2 content and 10% (mol useful gas mol(-1) toluene) energy yield. Moreover, at low S/C ratio, it had higher reaction activity and better ability to prevent coking. There is a small amount of carbon deposition in the form of amorphous carbon after 7h. Various characterization techniques such as XRD, FTIR and thermogravimetric were performed to investigate the coke deposition of Ni/olivine, Ni-Ce/olivine and Ni-Ce-Mg/olivine. It is suggested that 3% Ni-1% Ce-1% Mg/olivine was the most promising catalyst due to its minimum coke amount and the lower activation energy of coke burning. Copyright © 2014. Published by Elsevier Ltd.

Order-disorder in olivine minerals by synchrotron X-ray absorption near-edge structure (Xane) spectroscopy at the Mg, Fe and Ca K edges

Energy Technology Data Exchange (ETDEWEB)

Wu, Z.; Marcelli, A.; Cibin, G. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati; Mottana, A. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati; Rome Univ. Roma Tre, Rome (Italy). Dipt. di Scienze Geologiche; Paris, E.; Giuli, G [INFM, Camerino Univ., Camerino, MC (Italy). Dipt. di Scienze della Terra

1999-07-01

In this paper, are presented new, high-resolution experimental spectra at the Mg and Fe K edges for the two Fe-Mg end members F o and F a, and for three other olivines. Two are the Ca end members of the family, namely monticellite (Mtc: CaMgSiO4) and kirschsteinite (Krs: CaFeSiO4). The main purpose of this work is to investigate the effects of Mg, Fe, and Ca partition in the Pbnm (or {alpha}) olivine structure on the electronic properties, as well as the relationships that exist between chemical substitutions and features occurring in Xanes spectra. One wants to explore the relationships that intervene between LRO, as determined by XRD, and SRO, as determined by Xanes, on the endmembers and on a well-known intermediate member as well, and deduce from it a model for the behavior of the entire olivine solid-solution system.

Order-disorder in olivine minerals by synchrotron X-ray absorption near-edge structure (Xane) spectroscopy at the Mg, Fe and Ca K edges

International Nuclear Information System (INIS)

Wu, Z.; Marcelli, A.; Cibin, G.; Mottana, A.; Rome Univ. Roma Tre, Rome; Paris, E.; Giuli, G.

1999-01-01

In this paper, are presented new, high-resolution experimental spectra at the Mg and Fe K edges for the two Fe-Mg endmembers F o and F a, and for three other olivines. Two are the Ca endmembers of the family, namely monticellite (Mtc: CaMgSiO4) and kirschsteinite (Krs: CaFeSiO4). The main purpose of this work is to investigate the effects of Mg, Fe, and Ca partition in the Pbnm (or α) olivine structure on the electronic properties, as well as the relationships that exist between chemical substitutions and features occurring in Xanes spectra. One wants to explore the relationships that intervene between LRO, as determined by XRD, and SRO, as determined by Xanes, on the endmembers and on a well-known intermediate member as well, and deduce from it a model for the behavior of the entire olivine solid-solution system

The dissolution of high-FeO olivine rock from the Lovasjaervi intrusion (SE-Finland) at 25 deg. C as a function of pH

International Nuclear Information System (INIS)

Duro, Lara; El Aamrani, Fatima; Rovira, Miquel; Gimenez, Javier; Casas, Ignasi; Pablo, Joan de; Bruno, Jordi

2005-01-01

The high-FeO olivine-rich rock from the Lovasjaervi intrusion (65% olivine, 20% plagioclase, 8% magnetite, 4% pyroxene and 3% serpentine) has been proposed as a potential redox-active backfill-additive in deep high level nuclear waste repositories. In this work, the authors report on kinetic dissolution studies of this solid under different pH and redox conditions performed by using a flow-through methodology. Assuming that silicon is mainly released to solution from the olivine contained in the solid, the experimental results have been adjusted to an empirical rate law as a function of proton concentration. The proton concentration reaction orders agree with results found in the literature for both acidic and alkaline pH ranges. The calculations conducted with the reactive transport code RETRASO show that at alkaline pH, the olivine rock might have a lower redox buffer capacity than expected

Olivine Composition of the Mars Trojan 5261 Eureka: Spitzer IRS Data

Science.gov (United States)

Lim, L. F.; Burt, B. J.; Emery, J. P.; Mueller, M.; Rivkin, A. S.; Trilling, D.

2011-01-01

The largest Mars trojan, 5261 Eureka, is one of two prototype "Sa" asteroids in the Bus-Demeo taxonomy. Analysis of its visible/near-IR spectrum led to the conclusion that it might represent either an angritic analog or an olivine-rich composition such as an R chondrite. Spitzer IRS data (5-30 micrometers) have enabled us to resolve this ambiguity. The thermal-IR spectrum exhibits strong olivine reststrahlen features consistent with a composition of approximately equals Fo60-70. Laboratory spectra of R chondrites, brachinites, and chassignites are dominated by similar features.

Ph effect on tricalcium phosphate (Ca3(PO4)2) thermoluminescence

International Nuclear Information System (INIS)

Barrera V, A.; Zarate M, J.; Lemus R, J.; Sanchez, A.; Rivera M, T.

2015-10-01

The study of the ph effect is presented on thermoluminescent response of calcium phosphates synthesized by precipitation process. For the synthesis by precipitation, were used: calcium nitrate (Ca(NO 3 ) 2 and ammonium phosphate dibasic ((NH 4 ) 2 HPO 4 ) as precursors. Samples were obtained at ph 7, 8, 9 and 10 and subjected to a calcination s temperature of 1100 C. Samples were also irradiated with X rays of 6 MV to a dose of 2 Gy. Samples prior to irradiation showed no luminescence, the irradiated samples displayed a luminescent curve which is due to the X-ray response. Powders synthesized at ph 7 showed a well-defined peak centered at 267 grades C. The rest of the prepared samples showed a luminescent curve composed of several peaks. By analyzing the curve at ph 7 by the method of the shape of the curve, was found to have an order of 1.7, with an activation energy, E = 1.44 ± 0.04 eV. (Author)

Low-temperature plasticity of olivine revisited with in situ TEM nanomechanical testing.

Science.gov (United States)

Idrissi, Hosni; Bollinger, Caroline; Boioli, Francesca; Schryvers, Dominique; Cordier, Patrick

2016-03-01

The rheology of the lithospheric mantle is fundamental to understanding how mantle convection couples with plate tectonics. However, olivine rheology at lithospheric conditions is still poorly understood because experiments are difficult in this temperature range where rocks and mineral become very brittle. We combine techniques of quantitative in situ tensile testing in a transmission electron microscope and numerical modeling of dislocation dynamics to constrain the low-temperature rheology of olivine. We find that the intrinsic ductility of olivine at low temperature is significantly lower than previously reported values, which were obtained under strain-hardened conditions. Using this method, we can anchor rheological laws determined at higher temperature and can provide a better constraint on intermediate temperatures relevant for the lithosphere. More generally, we demonstrate the possibility of characterizing the mechanical properties of specimens, which can be available in the form of submillimeter-sized particles only.

Overexpression, crystallization and preliminary X-­ray crystallographic analysis of erythronate-4-phosphate dehydrogenase from Pseudomonas aeruginosa

Science.gov (United States)

Ha, Jun Yong; Lee, Ji Hyun; Kim, Kyoung Hoon; Kim, Do Jin; Lee, Hyung Ho; Kim, Hye-Kyung; Yoon, Hye-Jin; Suh, Se Won

2006-01-01

The enzyme erythronate-4-phosphate dehydrogenase catalyses the conversion of erythronate-4-phosphate to 3-hydroxy-4-phospho-hydroxy-α-ketobutyrate. It belongs to the d-isomer-specific 2-hydroxyacid dehydrogenase family. It is essential for de novo biosynthesis of vitamin B6 (pyridoxine). Erythronate-4-­phosphate dehydrogenase from Pseudomonas aeruginosa, a homodimeric enzyme consisting of two identical 380-residue subunits, has been overexpressed in Escherichia coli with a C-terminal purification tag and crystallized at 297 K using 0.7 M ammonium dihydrogen phosphate, 0.4 M ammonium tartrate, 0.1 M sodium citrate pH 5.6 and 10 mM cupric chloride. X-ray diffraction data were collected to 2.20 Å from a crystal grown in the presence of NADH. The crystals belong to the orthorhombic space group P212121, with unit-cell parameters a = 84.77, b = 101.28, c = 142.58 Å. A dimeric molecule is present in the asymmetric unit, giving a crystal volume per protein weight (V M) of 3.64 Å3 Da−1 and a solvent content of 66%. PMID:16511285

Phase evolution and photoluminescence enhancement of CePO4 nanowires from a low phosphate concentration system

International Nuclear Information System (INIS)

Xu Pengfei; Yu Ranbo; Zong Lingbo; Wang Jiali; Wang Dan; Deng Jinxia; Chen Jun; Xing Xianran

2013-01-01

Uniform CePO 4 nanowires have been successfully synthesized in a low phosphate concentration system through a single-step hydrothermal process. The low phosphate concentration might decrease the surface PO 4 3− adsorption of the as-synthesized CePO 4 nanowires efficiently and benefit their photoluminescence. The CePO 4 nanowires were identified to go through phase evolution from pure monoclinic to mixed hexagonal and monoclinic phase by only increasing the initial molar ratio of cerium and phosphate source (denoted as Ce/P). Interestingly, the strongest photoluminescence was observed in the CePO 4 nanowires synthesized with the initial Ce/P of 4:1, which proved to be the critical phase evolution point between the hexagonal and monoclinic CePO 4 . Therefore, the strong photoluminescence could be explained by the existence of the structure-sensitive energy level in the CePO 4 . This kind of photoluminescence enhancement would be a meaningful reference for design of other photoluminescent materials, in which the photoluminescent emission might be related to the structure-sensitive energy level. Additionally, the growth processes of CePO 4 nanowires based on related well-designed experiments were proposed.

Relict olivines in micrometeorites: Precursors and interactions in the earth`s atmosphere

Digital Repository Service at National Institute of Oceanography (India)

Rudraswami, N.G.; ShyamPrasad, M.; Dey, S.; Fernandes, D.; Plane, J.M.C.; Feng, W.; Taylor, S.; Carrillo-Sanchez, J.D.

is therefore useful for identifying the range of chondrites that contributes to the flux of micrometeorites (Steele, 1985a,b; Steele, 1992). The survival of the relict grains also 3    constrains the temperature the particle may have experienced during... elements present in the relict mineral helps narrow down the precursor with greater precision than the bulk chemical composition (Steele, 1985a, b; 1992), particularly because Mg-rich olivine can be compared with Mg-rich olivine in chondritic components...

Chemical differences between small subsamples of Apollo 15 olivine-normative basalts

Science.gov (United States)

Shervais, J. W.; Vetter, S. K.; Lindstrom, M. M.

1990-01-01

Results are presented on the chemical and petrological characterization of nine samples of an Apollo 15 mare basalt suite. The results show that all nine samples are low-silica olivine normative basalts (ONBs) similar to those described earlier for low-silica ONBs from Apollo 15 site. The samples were found to vary in texture and grain size, from fine-grained intergranular or subophitic basalts to coarse-grained granular 'microgabbros'. Several displayed macroscopic heterogeneity. Variation diagrams show that the overall trend of the data is consistent with the fractionation of olivine (plus minor Cr-spinel) from a high-MgO parent magma.

Betaine Phosphate (CH3)3N+CH2COO-.H3PO4 Modification Using D2O

International Nuclear Information System (INIS)

Saryati; Ridwan; Deswita; Sugiantoro, Sugik

2002-01-01

Betaine fosfate (CH 3 ) 3 N + CH 2 COO - .H 3 PO 4 modification by using D 2 O has been studied. This modification was carried out by slowly evaporation the saturated Betaine phosphat in the D 2 O solution in the dry box at 40 o C, until the dry crystal were formed. Based on the NMR data, can be concluded that the exchange process with D has been runed well and Betaine phosphate-D (CH 3 ) 3 N + CH 2 COO - .H 3 PO 4 has been resulted. From the X-ray diffraction pattern data can be concluded that there are a deference in the crystal structure between Betaine phosphate and Betaine phosphate modification result. From the Differential Scanning Colorimeter (DSC) diagram at the range temperature from 30 o C to 250 o C, can be shown that the Betaine phosphate-H has two endothermic transition phase, at 99 o C with a very little adsorbed calor and at 221.50 o C with -26.75 cal/g. Modified Betaine phosphate has also two endothermic transition phase, at 99.86 o C with -1.94 cal/g and at 171.01 o C with -3.48 cal/g. It can be conclosed that the D atom substitution on the H atoms in Betaine phosphate, to change the crystal and the endothermic fase temperature and energy

Aptamer-Conjugated Calcium Phosphate Nanoparticles for Reducing Diabetes Risk via Retinol Binding Protein 4 Inhibition.

Science.gov (United States)

Torabi, Raheleh; Ghourchian, Hedayatollah; Amanlou, Massoud; Pasalar, Parvin

2017-06-01

Inhibition of the binding of retinol to its carrier, retinol binding protein 4, is a new strategy for treating type 2 diabetes; for this purpose, we have provided an aptamer-functionalized multishell calcium phosphate nanoparticle. First, calcium phosphate nanoparticles were synthesized and conjugated to the aptamer. The cytotoxicity of nanoparticles releases the process of aptamer from nanoparticles and their inhibition function of binding retinol to retinol binding protein 4. After synthesizing and characterizing the multishell calcium phosphate nanoparticles and observing the noncytotoxicity of conjugate, the optimum time (48 hours) and the pH (7.4) for releasing the aptamer from the nanoparticles was determined. The half-maximum inhibitory concentration (IC 50 ) value for inhibition of retinol binding to retinol binding protein 4 was 210 femtomolar (fmol). The results revealed that the aptamer could prevent connection between retinol and retinol binding protein 4 at a very low IC 50 value (210 fmol) compared to other reported inhibitors. It seems that this aptamer could be used as an efficient candidate not only for decreasing the insulin resistance in type 2 diabetes, but also for inhibiting the other retinol binding protein 4-related diseases. Copyright © 2017 Diabetes Canada. Published by Elsevier Inc. All rights reserved.

Deriving global Olivine distribution on Hayabusa's target (25143) Itokawa using Near-Infrared Spectrometer data

Science.gov (United States)

Nardi, L.; Palomba, E.; Longobardo, A.; Galiano, A.; Dirri, F.

2017-09-01

In 2005 Hayabusa spacecraft visited asteroid Itokawa, bringing back surface samples to Earth in 2010. Near-Infrared data taken by NIRS and samples analysis confirmed hypothesis made through ground-based observations, in particular the one that sees Itokawa as an LL-chondrite like asteroid processed by space weathering. In this work, we apply spectral indices for olivine detection. In particular, we define the BAR* and relate it to the olivine abundance, by means of calibration on laboratory data. We present the distribution of BAR* calculated for nearly 38.000 spectra taken from an altitude of 3.5-7 km, defined as Home Position, which was the longest mission observation phase. In addition, a plot of olivine normalized content versus BAR* for RELAB compounds is given.

Effect of Phosphate Salts (Na3PO4, Na2HPO4, and NaH2PO4) on Ag3PO4 Morphology for Photocatalytic Dye Degradation under Visible Light and Toxicity of the Degraded Dye Products

NARCIS (Netherlands)

Amornpitoksuk, P; Intarasuwan, K; Suwanboon, S; Baltrusaitis, Jonas

2013-01-01

Ag3PO4 was synthesized by the precipitation method using three different types of phosphate salts (Na3PO4, Na2HPO4, and NaH2PO4) as a precipitating agent. Hydrolysis of each phosphate salt gave a specific pH that affected the purity and morphology of the prepared Ag3PO4. The Ag3PO4 prepared from

Melting mode and source lithology inferred from trace element systematic in historical olivine from Lanzarote, Canary Islands

Science.gov (United States)

Gómez-Ulla, Alejandra; Sigmarsson, Olgeir; Guðfinnsson, Guðmundur H.

2017-04-01

Trace element concentrations and ratios in olivine phenocrysts, such as fractionation-corrected Ni x (FeO/MgO) and Fe/Mn, have been shown useful as probes of pyroxenite derived component in mixtures of primary mantle melts (e.g. Sobolev et al., 2007). For instance, higher Ni and lower Mn and Ca contents are expected in partial melts of pyroxenite compared to those of lherzolite. We have measured trace element concentrations in olivine from 1730-1736 AD (Timanfaya) and 1824 AD eruptions in Lanzarote (Canary Islands), which erupted mafic and mantle nodule bearing magmas, ranging in composition from highly silica-undersaturated basanite through alkali basalt to tholeiite. The early basanite exhibit the largest olivine trace element variation covering the range of those from MORB and OIB worldwide, whereas later erupted tholeiite have values typical from pyroxenite derived melts. The Fo value decreased systematically with time during the 1730-36 eruption and the proportion of silica-saturated primary melt increased in the parental magma mixture with time. At the end of the eruption, tholeiite magmas crystallized olivine with, increasing concentrations of Mn and Ca and higher Ca/Al at relatively uniform Ni x (FeO/MgO) and Fe/Mn, all of which is readily explained by increased decompression melting at lower temperature. The basanite from the eruption that took place in 1824 AD has olivine with even higher Fo value and trace element variability similar those of the Timanfaya basanite. The fact that the Lanzarote basanite contain olivine with trace element systematic spanning that of MORB and pyroxenite melt can be explained by CO2-flux melting of a lithologically heterogeneous source, generating the diverse compositions. Initial reactive porous flow through depleted oceanic lithosphere and equilibration with dunitic restite of percolating pyroxenite melt may have amplified the observed Ni depletion in olivine of the earliest basanite. The fact that olivine compositions and

Experiments and geochemical modelling of CO{sub 2} sequestration by olivine: Potential, quantification

Energy Technology Data Exchange (ETDEWEB)

Garcia, B., E-mail: Bruno.Garcia@ifp.fr [Institut Francais du Petrole, 1 et 4 Avenue du Bois Preau, 92852 Rueil Malmaison (France); Beaumont, V.; Perfetti, E.; Rouchon, V.; Blanchet, D. [Institut Francais du Petrole, 1 et 4 Avenue du Bois Preau, 92852 Rueil Malmaison (France); Oger, P.; Dromart, G. [Universite de Lyon, CNRS, UMR 5570, ENS de Lyon, Site Monod, 15 Parvis Rene Descartes BP 7000, Lyon F-69342 (France); Huc, A.-Y.; Haeseler, F. [Institut Francais du Petrole, 1 et 4 Avenue du Bois Preau, 92852 Rueil Malmaison (France)

2010-09-15

Aqueous solutions equilibrated with supercritical CO{sub 2} (150 deg. C and total pressure of 150 bar) were investigated in order to characterize their respective conditions of carbonation. Dissolution of olivine and subsequent precipitation of magnesite with a net consumption of CO{sub 2} were expected. A quantified pure mineral phase (powders with different olivine grain diameter [20-80 {mu}m], [80-125 {mu}m], [125-200 {mu}m] and [>200 {mu}m]), and CO{sub 2} (as dried ice) were placed in closed-batch reactors (soft Au tubes) in the presence of solutions. Different salinities (from 0 to 3400 mM) and different ratios of solution/solid (mineral phase) (from 0.1 to 10) were investigated. Experiments were performed over periods from 2 to 8 weeks. Final solid products were quantified by the Rock-Eval 6 technique, and identified using X-ray diffraction, Raman spectroscopy, electron microprobe and scanning electron microscopy. Gaseous compounds were quantified by a vacuum line equipped with a Toepler pump and identified and measured by gas chromatography (GC). Carbon mass balances were calculated. Olivine reacted completely with CO{sub 2}, trapping up to 57 {+-} 2% (eqC of initial CO{sub 2}) as magnesite; some amorphous silica also formed. Olivine grain diameter and solution/mineral ratios appeared to be the primary controls on the reaction, salinity acting as a second order parameter. During the experiments, fluid analyses may not be performed with approach adopted but, geochemical modelling was attempted to give information about the solution composition. This showed an interesting mineral matrix evolution. Under the experimental conditions, olivine appeared to be a good candidate for CO{sub 2} trapping into a geologically stable carbonate, magnesite. The possible use of mafic and ultramafic rocks for CO{sub 2} sequestration is discussed.

Geometrically necessary dislocation densities in olivine obtained using high-angular resolution electron backscatter diffraction

Energy Technology Data Exchange (ETDEWEB)

Wallis, David, E-mail: davidwa@earth.ox.ac.uk [Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, Oxfordshire, OX1 3AN (United Kingdom); Hansen, Lars N. [Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, Oxfordshire, OX1 3AN (United Kingdom); Ben Britton, T. [Department of Materials, Imperial College London, Royal School of Mines, Exhibition Road, London SW7 2AZ (United Kingdom); Wilkinson, Angus J. [Department of Materials, University of Oxford, Parks Road, Oxford, Oxfordshire, OX1 3PH (United Kingdom)

2016-09-15

Dislocations in geological minerals are fundamental to the creep processes that control large-scale geodynamic phenomena. However, techniques to quantify their densities, distributions, and types over critical subgrain to polycrystal length scales are limited. The recent advent of high-angular resolution electron backscatter diffraction (HR-EBSD), based on diffraction pattern cross-correlation, offers a powerful new approach that has been utilised to analyse dislocation densities in the materials sciences. In particular, HR-EBSD yields significantly better angular resolution (<0.01°) than conventional EBSD (~0.5°), allowing very low dislocation densities to be analysed. We develop the application of HR-EBSD to olivine, the dominant mineral in Earth's upper mantle by testing (1) different inversion methods for estimating geometrically necessary dislocation (GND) densities, (2) the sensitivity of the method under a range of data acquisition settings, and (3) the ability of the technique to resolve a variety of olivine dislocation structures. The relatively low crystal symmetry (orthorhombic) and few slip systems in olivine result in well constrained GND density estimates. The GND density noise floor is inversely proportional to map step size, such that datasets can be optimised for analysing either short wavelength, high density structures (e.g. subgrain boundaries) or long wavelength, low amplitude orientation gradients. Comparison to conventional images of decorated dislocations demonstrates that HR-EBSD can characterise the dislocation distribution and reveal additional structure not captured by the decoration technique. HR-EBSD therefore provides a highly effective method for analysing dislocations in olivine and determining their role in accommodating macroscopic deformation. - Highlights: • Lattice orientation gradients in olivine were measured using HR-EBSD. • The limited number of olivine slip systems enable simple least squares inversion for GND

Mechanisms of electrical conductivity in olivine

International Nuclear Information System (INIS)

Schock, R.N.; Duba, A.G.; Shankland, T.J.

1984-01-01

Data on the electrical conductivity and the thermoelectric effect in single crystals indicate that the charge conduction mechanism in pure magnesium forsterite is electrons. The concentration of electrons can be varied by controlling the number of oxygen vacancies through manipulation of the oxygen pressure. For iron bearing olivine, the conduction mechanism is by electron holes localized on an iron ion. Since iron strongly affects the creep process as well, oxidation of iron is probably accompanied by the production of magnesium vacancies. 15 references

In Situ Laser Coating of Calcium Phosphate on TC4 Surface for Enhancing Bioactivity

Institute of Scientific and Technical Information of China (English)

DENG Chi; WANG Yong; ZHANG Ya-ping; GAO Jia-cheng

2007-01-01

Titanium alloy has been a successful implant material owing to its excellent ratio of strength to weight,toughness, and bio-inert oxide surface. Significant progress has been made in improving the bioactivity of titanium alloy by coating its oxide surface with calcium phosphates. In the present study, in situ coating was reported on Ti6Al4V(TC4) surface with calcium phosphate (Ca-P) bioceramics synthesized and synchronously cladded by laser beam. This coating was grown by first preplacing directly the raw powders, which contain 80% of CaHPO4 ·2H2O, 20% of CaCO3, and dram of rare earth (RE), on the TC4 surfaces, and then exposing the surfaces to the laser beam with a power density of 12. 73-15.27 MW · m-2 and a scanning velocity of 10. 5 m/s. The resultant coating was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis and Different-thermal Scanning (TG-DSC), and Energy Dispersive X-ray Detection (EDX). The results show that these laser ceramics include hydroxyapatite (HA), tricalcium phosphate (TCP), Ca2P2O7, and other Ca-P phases, and the interface between the coating and the TC4 substrate has tighter fixation, in which the chemical bonding is approved. These laser hybrid coatings are useful in enhancing the bioactivity of titanium alloy surfaces.

Synthesis, crystal structure and spectroscopy properties of Na 3AZr(PO 4) 3 ( A=Mg, Ni) and Li 2.6Na 0.4NiZr(PO 4) 3 phosphates

Science.gov (United States)

Chakir, M.; El Jazouli, A.; de Waal, D.

2006-06-01

Na 3AZr(PO 4) 3 ( A=Mg, Ni) phosphates were prepared at 750 °C by coprecipitation route. Their crystal structures have been refined at room temperature from X-ray powder diffraction data using Rietveld method. Li 2.6Na 0.4NiZr(PO 4) 3 was synthesized through ion exchange from the sodium analog. These materials belong to the Nasicon-type structure. Raman spectra of Na 3AZr(PO 4) 3 ( A=Mg, Ni) phosphates present broad peaks in favor of the statistical distribution in the sites around PO 4 tetrahedra. Diffuse reflectance spectra indicate the presence of octahedrally coordinated Ni 2+ ions.

Olivine on Vesta as exogenous contaminants brought by impacts: Constraints from modeling Vesta's collisional history and from impact simulations

Science.gov (United States)

Turrini, D.; Svetsov, V.; Consolmagno, G.; Sirono, S.; Pirani, S.

2016-12-01

The survival of asteroid Vesta during the violent early history of the Solar System is a pivotal constraint on theories of planetary formation. Particularly important from this perspective is the amount of olivine excavated from the vestan mantle by impacts, as this constrains both the interior structure of Vesta and the number of major impacts the asteroid suffered during its life. The NASA Dawn mission revealed that olivine is present on Vesta's surface in limited quantities, concentrated in small patches at a handful of sites not associated with the two large impact basins Rheasilvia and Veneneia. The first detections were interpreted as the result of the excavation of endogenous olivine, even if the depth at which the detected olivine originated was a matter of debate. Later works raised instead the possibility that the olivine had an exogenous origin, based on the geologic and spectral features of the deposits. In this work, we quantitatively explore the proposed scenario of a exogenous origin for the detected vestan olivine to investigate whether its presence on Vesta can be explained as a natural outcome of the collisional history of the asteroid over the last one or more billion years. To perform this study we took advantage of the impact contamination model previously developed to study the origin and amount of dark and hydrated materials observed by Dawn on Vesta, a model we updated by performing dedicated hydrocode impact simulations. We show that the exogenous delivery of olivine by the same impacts that shaped the vestan surface can offer a viable explanation for the currently identified olivine-rich sites without violating the constraint posed by the lack of global olivine signatures on Vesta. Our results indicate that no mantle excavation is in principle required to explain the observations of the Dawn mission and support the idea that the vestan crust could be thicker than indicated by simple geochemical models based on the Howardite

Electrical Investigation of Metal-Olivine Systems and Application to the Deep Interior of Mercury

Science.gov (United States)

Zhang, Zhou; Pommier, Anne

2017-12-01

We report electrical conductivity measurements on metal-olivine systems at about 5 and 6 GPa and up to 1,675°C in order to investigate the electrical properties of core-mantle boundary (CMB) systems. Electrical experiments were conducted in the multianvil apparatus using the impedance spectroscopy technique. The samples are composed of one metal layer (Fe, FeS, FeSi2, or Fe-Ni-S-Si) and one polycrystalline olivine layer, with the metal:olivine ratio ranging from 1:0.7 to 1:9.2. For all samples, we observe that the bulk electrical conductivity increases with temperature from 10-2.5 to 101.8 S/m, which is higher than the conductivity of polycrystalline olivine but lower than the conductivity of the pure metal phase at similar conditions. In some experiments, a conductivity jump is observed at the temperature corresponding to the melting temperature of the metallic phase. Both the metal:olivine ratio and the metal phase geometry control the electrical conductivity of the two-layer samples. By combining electrical results, textural analyses of the samples, and previous studies of the structure and composition of Mercury's interior, we propose an electrical profile of the deep interior of the planet that accounts for a layered CMB-outer core structure. The electrical model agrees with existing conductivity estimates of Mercury's lower mantle and CMB using magnetic observations and thermodynamic calculations, and thus, supports the hypothesis of a layered CMB-outermost core structure in the present-day interior of Mercury. We propose that the layered CMB-outer core structure is possibly electrically insulating, which may influence the planet's structure and cooling history.

Dielectric and mechanical properties of plasma-sprayed olivine

Czech Academy of Sciences Publication Activity Database

Ctibor, Pavel; Neufuss, Karel; Pala, Zdeněk; Kotlan, Jiří; Soumar, J.

2015-01-01

Roč. 67, č. 2 (2015), s. 600-616 ISSN 1221-1451. [International Conference on Plasma Physics and Applications/16./. Magurele, Bucharest, 20.06.2013-25.06.2013] Institutional support: RVO:61389021 Keywords : olivine * plasma spraying * dielectric properties Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.367, year: 2015 www.infim.ro/rrp

Chemical 3D-imaging of glass inclusions from allende (CV3) olivine via SIMS: A new insight on chondrule formation conditions

Science.gov (United States)

Florentin, L.; Deloule, E.; Faure, F.; Mangin, D.

2018-06-01

Natural glass inclusions - hosted in Mg-rich olivines from Allende (CV3) type I chondrules - and synthetic melt inclusions - trapped in forsterite crystallized from CMAS (CaO-MgO-Al2O3-SiO2) melts - were mapped by Secondary Ion Mass Spectrometry (SIMS) for CMAS major oxides. The first ever 3D chemical images of extra-terrestrial glass inclusions were obtained, along with chemical depth profiles for each oxide. Results show similar patterns for both synthetic glass inclusions (trapped in olivine formed by slow crystallization in a magmatic liquid) and natural inclusions from Allende's olivines. No incompatible-rich boundary layer or diffusion pattern was observed in either case. The absence of an incompatible-rich boundary layer suggests that the olivine overgrowth surrounding glass inclusions in Allende's olivines was formed during slow cooling of the host olivine and likely the surrounding chondrule. This provides new constraints on the cooling rates of type I chondrules.

Functional PEG–PAMAM-Tetraphosphonate Capped NaLnF4 Nanoparticles and their Colloidal Stability in Phosphate Buffer

Science.gov (United States)

2015-01-01

Developing surface coatings for NaLnF4 nanoparticles (NPs) that provide long-term stability in solutions containing competitive ions such as phosphate remains challenging. An amine-functional polyamidoamine tetraphosphonate (NH2-PAMAM-4P) as a multidentate ligand for these NPs has been synthesized and characterized as a ligand for the surface of NaGdF4 and NaTbF4 nanoparticles. A two-step ligand exchange protocol was developed for introduction of the NH2-PAMAM-4P ligand on oleate-capped NaLnF4 NPs. The NPs were first treated with methoxy-poly(ethylene glycol)-monophosphoric acid (Mn = 750) in tetrahydrofuran. The mPEG750-OPO3-capped NPs were stable colloidal solutions in water, where they could be ligand-exchanged with NH2-PAMAM-4P. The surface amine groups on the NPs were available for derivatization to attach methoxy-PEG (Mn = 2000) and biotin-terminated PEG (Mn = 2000) chains. The surface coverage of ligands on the NPs was examined by thermal gravimetric analysis, and by a HABA analysis for biotin-containing NPs. Colloidal stability of the NPs was examined by dynamic light scattering. NaGdF4 and NaTbF4 NPs capped with mPEG2000–PAMAM-4P showed colloidal stability in DI water and in phosphate buffer (10 mM, pH 7.4). A direct comparison with NaTbF4 NPs capped with a mPEG2000-lysine-based tetradentate ligand that we reported previously (Langmuir2012, 28, 12861−1287022906305) showed that both ligands provided long-term stability in phosphate buffer, but that the lysine-based ligand provided better stability in phosphate-buffered saline. PMID:24898128

Removal of phosphate from solution by adsorption and precipitation of calcium phosphate onto monohydrocalcite.

Science.gov (United States)

Yagi, Shintaro; Fukushi, Keisuke

2012-10-15

The sorption behavior and mechanism of phosphate on monohydrocalcite (CaCO(3)·H(2)O: MHC) were examined using batch sorption experiments as a function of phosphate concentrations, ionic strengths, temperatures, and reaction times. The mode of PO(4) sorption is divisible into three processes depending on the phosphate loading. At low phosphate concentrations, phosphate is removed by coprecipitation of phosphate during the transformation of MHC to calcite. The sorption mode at the low-to-moderate phosphate concentrations is most likely an adsorption process because the sorption isotherm at the conditions can be fitted reasonably with the Langmuir equation. The rapid sorption kinetics at the conditions is also consistent with the adsorption reaction. The adsorption of phosphate on MHC depends strongly on ionic strength, but slightly on temperature. The maximum adsorption capacities of MHC obtained from the regression of the experimental data to the Langmuir equation are higher than those reported for stable calcium carbonate (calcite or aragonite) in any conditions. At high phosphate concentrations, the amount of sorption deviates from the Langmuir isotherm, which can fit the low-to-moderate phosphate concentrations. Speciation-saturation analyses of the reacted solutions at the conditions indicated that the solution compositions which deviate from the Langmuir equation are supersaturated with respect to a certain calcium phosphate. The obtained calcium phosphate is most likely amorphous calcium phosphate (Ca(3)(PO(4))(2)·xH(2)O). The formation of the calcium phosphate depends strongly on ionic strength, temperature, and reaction times. The solubility of MHC is higher than calcite and aragonite because of its metastability. Therefore, the higher solubility of MHC facilitates the formation of the calcium phosphates more than with calcite and aragonite. Copyright © 2012 Elsevier Inc. All rights reserved.

Anion and cation partitioning between olivine, plagioclase phenocrysts and the host magma

International Nuclear Information System (INIS)

Yurimoto, Hisayoshi; Sueno, Shigeho

1984-01-01

Partition coefficients for -1, -2, -3, +1, +2, +3, +4 and +5 valent ions between the groundmass of tholeiite basalt and coexisting olivine and plagioclase phenocrysts from the Mid-Atlantic Ridge have been determined by secondary ion mass spectrometry. The present cation partitioning strongly supports the 'crystal structure control' mechanism. The partition coefficient for an anion is also under control of the crystal structure, so that each of the cation and anion positions in the crystal structure gives rise to a parabola-shaped peak on the partition coefficient vs. ionic radius diagram. (author)

Enhanced thermal and structural properties of partially phosphorylated polyvinyl alcohol - Aluminum phosphate (PPVA-Alpo4) nanocomposites with aluminium nitrate source

Science.gov (United States)

Saat, Asmalina Mohamed; Johan, Mohd Rafie

2017-12-01

Synthesis of AlPO4 nanocomposite depends on the ratio of aluminum to phosphate, method of synthesis and the source for aluminum and phosphate source used. Variation of phosphate and aluminum source used will form multiple equilibria reactions and affected by ions variability and concentration, stoichiometry, temperature during reaction process and especially the precipitation pH. Aluminum nitrate was used to produce a partially phosphorylated poly vinyl alcohol-aluminum phosphate (PPVA-AlPO4) nanocomposite with various nanoparticle shapes, structural and properties. Synthesis of PPVA-AlPO4 nanocomposite with aluminum nitrate shows enhancement of thermal and structural in comparison with pure PVA and modified PPVA. Thermogravimetric (TGA) analysis shows that the weight residue of PPVA-AlPO4 composite was higher than PPVA and PVA. X-ray diffraction (XRD) pattern of PVA shows a single peak broadening after the addition of phosphoric acid. Meanwhile, XRD pattern of PPVA-AlPO4 demonstrates multiple phases of AlPO4 in the nanocomposite. Field Emission Scanning Electron Microscopy (FESEM) confirmed the existence of multiple geometrical phases and nanosize of spherical particles.

Geoengineering impact of open ocean dissolution of olivine on atmospheric CO2, surface ocean pH and marine biology

International Nuclear Information System (INIS)

Köhler, Peter; Abrams, Jesse F; Völker, Christoph; Hauck, Judith; Wolf-Gladrow, Dieter A

2013-01-01

Ongoing global warming induced by anthropogenic emissions has opened the debate as to whether geoengineering is a ‘quick fix’ option. Here we analyse the intended and unintended effects of one specific geoengineering approach, which is enhanced weathering via the open ocean dissolution of the silicate-containing mineral olivine. This approach would not only reduce atmospheric CO 2 and oppose surface ocean acidification, but would also impact on marine biology. If dissolved in the surface ocean, olivine sequesters 0.28 g carbon per g of olivine dissolved, similar to land-based enhanced weathering. Silicic acid input, a byproduct of the olivine dissolution, alters marine biology because silicate is in certain areas the limiting nutrient for diatoms. As a consequence, our model predicts a shift in phytoplankton species composition towards diatoms, altering the biological carbon pumps. Enhanced olivine dissolution, both on land and in the ocean, therefore needs to be considered as ocean fertilization. From dissolution kinetics we calculate that only olivine particles with a grain size of the order of 1 μm sink slowly enough to enable a nearly complete dissolution. The energy consumption for grinding to this small size might reduce the carbon sequestration efficiency by ∼30%. (letter)

Trace elements in olivine of ultramafic lamprophyres controlled by phlogopite-rich mineral assemblages in the mantle source

Science.gov (United States)

Veter, Marina; Foley, Stephen F.; Mertz-Kraus, Regina; Groschopf, Nora

2017-11-01

Carbonate-rich ultramafic lamprophyres (aillikites) and associated rocks characteristically occur during the early stages of thinning and rifting of cratonic mantle lithosphere, prior to the eruption of melilitites, nephelinites and alkali basalts. It is accepted that they require volatile-rich melting conditions, and the presence of phlogopite and carbonate in the source, but the exact source rock assemblages are debated. Melts similar to carbonate-rich ultramafic lamprophyres (aillikites) have been produced by melting of peridotites in the presence of CO2 and H2O, whereas isotopes and trace elements appear to favor distinct phlogopite-bearing rocks. Olivine macrocrysts in aillikites are usually rounded and abraded, so that it is debated whether they are phenocrysts or mantle xenocrysts. We have analyzed minor and trace element composition in olivines from the type aillikites from Aillik Bay in Labrador, Canada. We characterize five groups of olivines: [1] mantle xenocrysts, [2] the main phenocryst population, and [3] reversely zoned crystals interpreted as phenocrysts from earlier, more fractionated, magma batches, [4] rims on the phenocrysts, which delineate aillikite melt fractionation trends, and [5] rims around the reversely zoned olivines. The main phenocryst population is characterized by mantle-like Ni (averaging 3400 μg g- 1) and Ni/Mg at Mg# of 88-90, overlapping with phenocrysts in ocean island basalts and Mediterranean lamproites. However, they also have low 100 Mn/Fe of 0.9-1.3 and no correlation between Ni and other trace elements (Sc, Co, Li) that would indicate recycled oceanic or continental crust in their sources. The low Mn/Fe without high Ni/Mg, and the high V/Sc (2-5) are inherited from phlogopite in the source that originated by solidification of lamproitic melts at the base of the cratonic lithosphere in a previous stage of igneous activity. The olivine phenocryst compositions are interpreted to result from phlogopite and not high modal

Olivine-bearing lithologies on the Moon: Constraints on origins and transport mechanisms from M3 spectroscopy, radiative transfer modeling, and GRAIL crustal thickness

Science.gov (United States)

Corley, Laura M.; McGovern, Patrick J.; Kramer, Georgiana Y.; Lemelin, Myriam; Trang, David; Gillis-Davis, Jeffrey J.; Taylor, G. Jeffrey; Powell, Kathryn E.; Kiefer, Walter S.; Wieczorek, Mark; Zuber, Maria T.

2018-01-01

High-resolution hyperspectral data from Chandrayaan-1's Moon Mineralogy Mapper (M3) allow detection of olivine on the lunar surface. Olivine exposed at the surface may originate as mantle material or igneous products (intrusive or extrusive). Potential transport mechanisms include excavation of the mantle or lower crustal material by impacts that form basins and complex craters, differentiation of impact melt sheets, or magmatic emplacement of lavas, cumulates, or xenoliths. A sample of the lunar mantle, which has not been conclusively identified in the lunar sample collection, would yield fundamental new insights into the composition, structure, and evolution of the lunar interior. Olivine identified in remote spectral data is generally accepted to originate from the primary mantle, because abundant olivine is expected to exist in the mantle and lower crust, yet have sparse occurrences in the upper crust. In this study, we identified 111 M3 single-pixel spectra with characteristic absorption features consistent with olivine at Crisium, Nectaris, and Humorum basins and near the craters Roche and Tsiolkovsky. In an effort to determine the origins and transport mechanisms that led to these individual exposures, we estimated mineral abundances using radiative transfer modeling and examined crustal thickness estimates, topography and slope maps, and images from the Lunar Reconnaissance Orbiter Camera (LROC). At Crisium basin, where crustal thickness is near 0 km (Wieczorek et al., 2013), mantle olivine may have been exposed by basin-forming impact and deposited on the rim. Picard crater, which is superposed on the floor of Crisium, also exhibits potential mantle olivine in its ejecta. Within Nectaris basin, olivine exposures are confined to the rims of small craters on the mare, which are inferred to excavate a layer of olivine-rich mare basalt. Olivine occurrences on the rim of Humorum basin, including those located on a graben, are likely to be cumulates of shallow

Structural Transformation of LiFePO4 during Ultrafast Delithiation.

Science.gov (United States)

Kuss, Christian; Trinh, Ngoc Duc; Andjelic, Stefan; Saulnier, Mathieu; Dufresne, Eric M; Liang, Guoxian; Schougaard, Steen B

2017-12-21

The prolific lithium battery electrode material lithium iron phosphate (LiFePO 4 ) stores and releases lithium ions by undergoing a crystallographic phase change. Nevertheless, it performs unexpectedly well at high rate and exhibits good cycling stability. We investigate here the ultrafast charging reaction to resolve the underlying mechanism while avoiding the limitations of prevailing electrochemical methods by using a gaseous oxidant to deintercalate lithium from the LiFePO 4 structure. Oxidizing LiFePO 4 with nitrogen dioxide gas reveals structural changes through in situ synchrotron X-ray diffraction and electronic changes through in situ UV/vis reflectance spectroscopy. This study clearly shows that ultrahigh rates reaching 100% state of charge in 10 s does not lead to a particle-wide union of the olivine and heterosite structures. An extensive solid solution phase is therefore not a prerequisite for ultrafast charge/discharge.

Virtual synthesis of crystals using ab initio MD: Case study on LiFePO4

Science.gov (United States)

Mishra, S. B.; Nanda, B. R. K.

2017-05-01

Molecular dynamics simulation technique is fairly successful in studying the structural aspects and dynamics of fluids. Here we study the ability of ab initio molecular dynamics (ab initio MD) to carry out virtual experiments to synthesize new crystalline materials and to predict their structures. For this purpose the olivine phosphate LiFePO4 (LFPO) is used as an example. As transition metal oxides in general are stabilized with layered geometry, we carried out ab initio MD simulations over a hypothetical layered configuration consisting of alternate LiPO2 and FeO2 layers. With intermittent steps of electron minimization, the resulted equilibrium lattice consist of PO4 tetrahedra and distorted Fe-O complexes similar to the one observed in the experimental lattice.

Scrap tire pyrolysis using a new type two-stage pyrolyzer: Effects of dolomite and olivine on producing a low-sulfur pyrolysis oil

International Nuclear Information System (INIS)

Choi, Gyung-Goo; Oh, Seung-Jin; Kim, Joo-Sik

2016-01-01

Scrap tire pyrolysis was performed using a two-stage pyrolyzer consisting of an auger reactor and a fluidized bed reactor to produce a low-sulfur pyrolysis oil. In the experiments, the effect of the residence time of the feed material in the auger reactor was investigated at ∼300 (auger reactor) and 500 °C (fluidized bed reactor). In addition, natural dolomite and olivine and calcined dolomite and olivine were used as the fluidized bed materials to examine their effects on reducing the sulfur content of pyrolysis oil. In the experiments, the yields of the oil from the auger reactor were 1.4–3.7 wt%, and it was enriched with DL-limonene whose content in the oil was 40–50 wt%. The yields of the oil from the fluidized bed reactor were 42–46 wt%. The optimum residence time of the feed material in the auger reactor turned out to be 3.5 min. Calcined dolomite and olivine significantly decreased the sulfur content of pyrolysis oil. Metal oxides of the additives appeared to react with H_2S to form metal sulfides. The sulfur content of pyrolysis oil obtained with calcined olivine was 0.45 wt%. - Highlights: • Scrap tires were successfully pyrolyzed in a new type two-stage pyrolyzer. • The two-stage pyrolyzer is composed of an auger and fluidized bed reactors. • Calcination of olivine and dolomite led to a strong decrease in sulfur. • The lowest sulfur content of pyrolysis oil was 0.45 wt%. • Pyrolysis oil yields from the fluidized bed reactor were 43–46 wt%.

Olivine, dolomite and ceramic filters in one vessel to produce clean gas from biomass.

Science.gov (United States)

Rapagnà, Sergio; Gallucci, Katia; Foscolo, Pier Ugo

2018-01-01

Heavy organic compounds produced during almond shells gasification in a steam and/or air atmosphere, usually called tar, are drastically reduced in the product gas by using simultaneously in one vessel a ceramic filter placed in the freeboard and a mixture of olivine and dolomite particles in the fluidized bed of the gasifier. The content of tar in the product gas during a reference gasification test with air, in presence of fresh olivine particles only, was 8600mg/Nm 3 of dry gas. By gasifying biomass with steam at the same temperature level of 820°C in a bed of olivine and dolomite (20% by weight), and in the presence of a catalytic ceramic filter inserted in the freeboard of the fluidized bed gasifier, the level of tar was brought down to 57mg/Nm 3 of dry producct gas, with a decrease of more than two orders of magnitude. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of water activity on rates of serpentinization of olivine.

Science.gov (United States)

Lamadrid, Hector M; Rimstidt, J Donald; Schwarzenbach, Esther M; Klein, Frieder; Ulrich, Sarah; Dolocan, Andrei; Bodnar, Robert J

2017-07-14

The hydrothermal alteration of mantle rocks (referred to as serpentinization) occurs in submarine environments extending from mid-ocean ridges to subduction zones. Serpentinization affects the physical and chemical properties of oceanic lithosphere, represents one of the major mechanisms driving mass exchange between the mantle and the Earth's surface, and is central to current origin of life hypotheses as well as the search for microbial life on the icy moons of Jupiter and Saturn. In spite of increasing interest in the serpentinization process by researchers in diverse fields, the rates of serpentinization and the controlling factors are poorly understood. Here we use a novel in situ experimental method involving olivine micro-reactors and show that the rate of serpentinization is strongly controlled by the salinity (water activity) of the reacting fluid and demonstrate that the rate of serpentinization of olivine slows down as salinity increases and H 2 O activity decreases.

Effect of water activity on rates of serpentinization of olivine

Science.gov (United States)

Lamadrid, Hector M.; Rimstidt, J. Donald; Schwarzenbach, Esther M.; Klein, Frieder; Ulrich, Sarah; Dolocan, Andrei; Bodnar, Robert J.

2017-07-01

The hydrothermal alteration of mantle rocks (referred to as serpentinization) occurs in submarine environments extending from mid-ocean ridges to subduction zones. Serpentinization affects the physical and chemical properties of oceanic lithosphere, represents one of the major mechanisms driving mass exchange between the mantle and the Earth's surface, and is central to current origin of life hypotheses as well as the search for microbial life on the icy moons of Jupiter and Saturn. In spite of increasing interest in the serpentinization process by researchers in diverse fields, the rates of serpentinization and the controlling factors are poorly understood. Here we use a novel in situ experimental method involving olivine micro-reactors and show that the rate of serpentinization is strongly controlled by the salinity (water activity) of the reacting fluid and demonstrate that the rate of serpentinization of olivine slows down as salinity increases and H2O activity decreases.

Effect of iron content on the creep behavior of Olivine: 2. Hydrous conditions

Science.gov (United States)

Zhao, Yong-Hong; Zimmerman, Mark E.; Kohlstedt, David L.

2018-05-01

We have undertaken an experimental investigation of the effect of iron content on the viscosity of Fe-Mg olivine aggregates deformed under hydrous conditions in order to provide a basis for comparing convection models for the mantle of Earth with those for the more iron-rich mantle of Mars. Fine-grained samples of Fe-bearing olivine with fayalite contents, Fax, of x = 100, 75, 50, 30 and 10 were deformed in triaxial compressive creep primarily in the dislocation creep regime under water-saturated conditions at temperatures of 1273 to 1473 K and a confining pressure of 300 MPa. Nickel sleeves around the samples of Fa10, Fa30 and Fa50 set the oxygen fugacity at the Ni:NiO buffer and thus the water fugacity at ≲300 MPa, while Fe sleeves around samples of Fa75 and Fa100 set the oxygen fugacity at the Fe:FeO buffer and thus the water fugacity at ≲200 MPa. Samples were deformed in triaxial compression to a maximum strain of 0.2 at differential stresses from 10 to 300 MPa and strain rates from 10-7 to 10-3 s-1. In the dislocation creep field at a given temperature, the viscosity of samples of Fa50 is a factor of ∼10 smaller than the viscosity of samples of Fa30, while the viscosity of samples of Fa30 is a factor of ∼10 smaller than that of samples of Fa10. Our experimental results can be described by the flow law ε˙disl =Cdisl(σ/μ) ndisl XFa pdisl exp(-(Qdisl0 +αdislXFa)/RT) fH2Omdisl with Cdisl = 99.7 MPa-5/4 s-1, ndisl = 3.7, pdisl = 0.5, Qdisl0 = 510 kJ/mol, αdisl = -120 kJ/mol, and mdisl = 5/4. This flow law indicates that the viscosity of olivine of a specific Fe:Mg ratio is a factor of ∼10 smaller than its counterpart deformed under anhydrous conditions. In a hydrous environment at the same thermodynamic conditions, the viscosity of the more Fe-rich mantle (∼Fa19) of Mars is a factor of ∼5 lower than that of the mantle (∼Fa8) of Earth.

Polymorphism and piezochromicity in the three-dimensional network-based phosphate RbCuPO4

International Nuclear Information System (INIS)

Henry, Paul F.; Kimber, Simon A.J.; Argyriou, Dimitri N.

2010-01-01

Rubidium copper phosphate, RbCuPO 4 , forms two roomtemperature polymorphs that have been investigated with neutron powder diffraction. Polymorph (II) can be converted quantitatively into (I) by grinding the material or by pelletization, and the phase transition is accompanied by a significant colour change from very pale green to sky blue. Polymorph (II) can be obtained essentially free of (I) by quenching from 723 K. Each polymorph shows two unique Cu atoms: in (I) both sites are four-coordinate in a 2:1 ratio, whereas in (II) the atoms are four- and five-coordinate in a 1:1 ratio. In each case these sites are linked by phosphate tetrahedra to form three-dimensional frameworks based on the 42638-a four-connected net. The Rb atoms are hosted in the six- and eight-ring channels that are similar to those observed in zeolite ABW. The (II)→(I) phase transition is also accompanied by a volume reduction of 2.1% even though the average coordination of the Cu atoms also falls. The structures of the polymorphs are critically examined and compared with those of KNiPO 4 and KCuPO 4 in terms of hexagonal close packing containing ordered phosphate arrays. As a result of buckling of the six-ring layers, one-dimensional chains of dimerized copper polyhedra are identified in (II), chains that become trimers with mirror symmetry in (I). (orig.)

Synthesis and Properties of Biodegradable Copolymers of 9-Phenyl-2,4,8,10-tetraoxaspiro-[5,5]undcane-3-one and Ethylene Ethyl Phosphate

Institute of Scientific and Technical Information of China (English)

Jian XU; Zhi Lan LIU; Ren Xi ZHUO

2006-01-01

Novel biodegradable copolymer poly(CC-co-EEP) was synthesized by ring-opening copolymerization of cyclic carbonate 9-phenyl-2, 4, 8, 10-tetraoxaspiro-[5, 5]undcane-3-one (CC)and ethylene ethyl phosphate (EEP). The obtained poly (CC-co-EEP)s were characterized by FTIR, 1H NMR, 13C NMR and gel permeation chromatography (GPC). In vitro hydrolytic degradation of the copolymers were investigated in phosphate buffer solution (pH=7.4).Hydrophilic phosphate units apparently improved the degradability of poly(carbonate-phosphate).

The Effect of Hydrothermal Treatment on Olivine Nano-Silica

NARCIS (Netherlands)

Griend, van de M.C; Lazaro, A.; Brouwers, H.J.H.

2012-01-01

This paper provides an overview of the effects of ripening the olivine nano-silica to form particles with a lower specific surface area for optimal use in high performance concrete. The nano-silica was ripened using a hydrothermal treatment in a mixed batch reactor at 90 C, pH ranging from 8 to 10

Temperature dependence of the quadrupole splitting of olivine and pyroxene from the Plains of Gusev Crater on Mars

International Nuclear Information System (INIS)

Agresti, David G.

2012-01-01

In the present work, we report application of simultaneous fitting procedures to Mössbauer data acquired on the Plains of Gusev Crater by the MIMOS II spectrometer on board the Mars Exploration Rover Spirit. Based on a quantitative measure of spectrum quality, the 34 best of the ∼126 spectra acquired on the Plains are grouped together for a single simultaneous fit with a common least-squares criterion. Fitted values for the quadrupole splitting (QS) of olivine (Ol) from 200 K to 260 K are shown to lie between reported trend lines for Fo50 and Fo30 olivine, with a temperature gradient of (−11.2 ± 1.2) × 10  − 4 mm/s/K, a nearly five-fold improvement in precision over the previously reported value, enabling extrapolation to QS(Ol) = (2.93 ± 0.01) mm/s at 295 K. QS of pyroxene fit as a single doublet exhibits a temperature gradient of (−7.3 ± 2.3) × 10  − 4 mm/s/K.

Olivine-melt relationships and syneruptive redox variations in the 1959 eruption of Kīlauea Volcano as revealed by XANES

Science.gov (United States)

Helz, Rosalind L.; Cottrell, Elizabeth; Brounce, Maryjo N.; Kelley, Katherine A.

2017-01-01

The 1959 summit eruption of Kīlauea Volcano exhibited high lava fountains of gas-rich, primitive magma, containing olivine + chromian spinel in highly vesicular brown glass. Microprobe analysis of these samples shows that euhedral rims on olivine phenocrysts, in direct contact with glass, vary significantly in forsterite (Fo) content, at constant major-element melt composition, as do unzoned groundmass olivine crystals. Ferric/total iron (Fe+ 3/FeT)ratios for matrix and interstitial glasses, plus olivine-hosted glass inclusions in eight 1959 scoria samples have been determined by micro X-ray absorption near-edge structure spectroscopy (μ-XANES). These data show that much of the variation in Fo content reflects variation in oxidation state of iron in the melt, which varies with sulfur concentration in the glass and (locally) with proximity to scoria edges in contact with air. Data for 24 olivine-melt pairs in the better-equilibrated samples from later in the eruption show KD averaging 0.280 ± 0.03 for the exchange of Fe and Mg between olivine and melt, somewhat displaced from the value of 0.30 ± 0.03 given by Roeder and Emslie (1970). This may reflect the low SiO2 content of the 1959 magmas, which is lower than that in most Kīlauea tholeiites. More broadly, we show the potential of μ-XANES and electron microprobe to revisit and refine the value of KD in natural systems.The observed variations of Fe+ 3/FeT ratios in the glasses reflect two distinct processes. The main process, sulfur degassing, produces steady decrease of the Fe+ 3/FeT ratio. Melt inclusions in olivine are high in sulfur (1060–1500 ppm S), with Fe+ 3/FeT = 0.160–0.175. Matrix glasses are degassed (mostly S eruption and (2) the melts originally had Fe+ 3/FeT ≥ 0.175, consistent with oxygen fugacity (fO2) at least 0.4 log units above the fayalite-magnetite-quartz (FMQ) buffer at 1 atm and magmatic temperature of 1200 °C.The second process is interaction between the

Spectroscopy of olivine basalts using FieldSpec and ASTER data: A ...

Indian Academy of Sciences (India)

Several volcanic episodes occurred during Early- to Late-. Cretaceous are ... produce a new scene that has the best of orig- ... developed from an olivine basalt parent magma, ..... Marcelino E, Formaggio A and Maeda E 2009 Landslide.

Role of Phosphate Transport System Component PstB1 in Phosphate Internalization by Nostoc punctiforme.

Science.gov (United States)

Hudek, L; Premachandra, D; Webster, W A J; Bräu, L

2016-11-01

In bacteria, limited phosphate availability promotes the synthesis of active uptake systems, such as the Pst phosphate transport system. To understand the mechanisms that facilitate phosphate accumulation in the cyanobacterium Nostoc punctiforme, phosphate transport systems were identified, revealing a redundancy of Pst phosphate uptake systems that exists across three distinct operons. Four separate PstB system components were identified. pstB1 was determined to be a suitable target for creating phenotypic mutations that could result in the accumulation of excessive levels of phosphate through its overexpression or in a reduction of the capacity to accumulate phosphate through its deletion. Using quantitative real-time PCR (qPCR), it was determined that pstB1 mRNA levels increased significantly over 64 h in cells cultured in 0 mM added phosphate and decreased significantly in cells exposed to high (12.8 mM) phosphate concentrations compared to the level in cells cultured under normal (0.8 mM) conditions. Possible compensation for the loss of PstB1 was observed when pstB2, pstB3, and pstB4 mRNA levels increased, particularly in cells starved of phosphate. The overexpression of pstB1 increased phosphate uptake by N. punctiforme and was shown to functionally complement the loss of PstB in E. coli PstB knockout (PstB - ) mutants. The knockout of pstB1 in N. punctiforme did not have a significant effect on cellular phosphate accumulation or growth for the most part, which is attributed to the compensation for the loss of PstB1 by alterations in the pstB2, pstB3, and pstB4 mRNA levels. This study provides novel in vivo evidence that PstB1 plays a functional role in phosphate uptake in N. punctiforme IMPORTANCE: Cyanobacteria have been evolving over 3.5 billion years and have become highly adept at growing under limiting nutrient levels. Phosphate is crucial for the survival and prosperity of all organisms. In bacteria, limited phosphate availability promotes the

Use of [18O4] phosphoric acid in the quantitation of phosphate by gas-liquid chromatography-mass spectrometry analysis

International Nuclear Information System (INIS)

Graff, G.; Krick, T.P.; Walseth, T.F.; Goldberg, N.D.

1980-01-01

A procedure is described to quantitate inorganic phosphate in the form of the tris(trimethylsilyl) (TMS) phosphate by gas-liquid chromatography-mass spectrometry (glc-ms) that increases the previously reported detection limit from the microgram to the nanogram range. The sensitivity for detecting TMS-phosphate by glc-ms analysis was shown to be limited by an increasing fractional loss with decreasing concentrations of TMS-phosphate analyzed due to its adsorption on different types of glc column supports. The method developed employs [ 18 O 4 ] phosphoric acid which serves as both an internal standard to permit quantitation and as a carrier to minimize sample adsorption on the glc column support

Ternary phosphates in Ca3(PO4)2-Na3Ln(PO4)2 (Ln-Nd, Eu, Er) systems

International Nuclear Information System (INIS)

Lazoryak, B.I.; Ivanov, L.N.; Strunenkova, T.V.; Golubev, V.N.; Viting, B.N.

1990-01-01

Ternary phosphates, formed in Ca 3 (PO 4 ) 2 -Na 3 Ln(PO 4 ) 2 (Ln-Nd, Eu, Er) systems were investigated by the methods of X-ray phase, luminescent analyses and IR spectroscopy. 5 regions of homogeneity were found. Two of them (I and II) were distinguished for all systems. Samples in the region of up to 14.285 mol.% Na 3 Ln(PO 4 ) 2 crystallize on the basis of β-Ca 3 (PO 4 ) 2 structure, and in other homogeneity regions - on the basis of β-K 2 SO 4 structure

Availability of rock phosphate with low P content in some Albanian soil: use of 32PO4

International Nuclear Information System (INIS)

Fardeau, J.C.; Migadel, F.; Gjermani, A.; Malja, S.

1983-10-01

The availability of a calcareous low P content rock phosphate (4,3% P) was measured. This Albanian ore was used, in pot experiments, on various local soils whose the pH is situated between 4,9 to 7,5. This phosphate was labelled with 32 P and 45 Ca in a reactor. The residual effect of this fertilizer was deduced from the results of isotopic dilution kinetic of phosphate ions realized in soil-solution systemes. The main results can be summarized as follow: 1. When the soil-water pH was higher than 6,1, the utilization coefficient of phosphorus was minus than 1%, even with 5,5 mounths. 2. The ratio of P and Ca derived from fertilizer and taken up by the crop is most generally different of those measured in the fertilizer. It depends of the soil constitution. 3. The analysis of isotopic dilution kinetic of phosphate ions shows that in the major part of these soils, whose the fixing capacity is very high, the rock phosphate and also superphosphate at 230 kg P 2 O 5 .ha -1 rate does not increase available soil phosphorus; it is only with rates over 800 kg P 2 O 5 .ha -1 that this objective can be reached. These results explain again that the fixing capacity of soil for phosphorus is a characteristic more useful for fertilization technique than the available phosphorus quantity [fr

Osh4p is needed to reduce the level of phosphatidylinositol-4-phosphate on secretory vesicles as they mature

OpenAIRE

Ling, Yading; Hayano, Scott; Novick, Peter

2014-01-01

Phosphatidylinositol-4-phosphate (PI4P) is produced on both the Golgi and the plasma membrane. Despite extensive vesicular traffic between these compartments, genetic analysis suggests that the two pools of PI4P do not efficiently mix with one another. Several lines of evidence indicate that the PI4P produced on the Golgi is normally incorporated into secretory vesicles, but the fate of that pool has been unclear. We show here that in yeast the oxysterol-binding proteins Osh1?Osh7 are collect...

Preparation of calcium phosphate paste

International Nuclear Information System (INIS)

Mohd Reusmaazran Yusof; Norzita Yaacob; Idris Besar; Che Seman Mahmood; Rusnah Mustafa

2010-01-01

Calcium phosphate paste were prepared by mixing between calcium sodium potassium phosphate, Ca 2 NaK (PO 4 ) 2 (CSPP) and monocalcium phosphate monohydrate, Ca(H 2 PO 4 ) 2 .H 2 O (MCPM). CSPP were obtained by reaction between calcium hydrogen phosphate (CaHPO 4 ), potassium carbonate (K 2 CO 3 ) and sodium carbonate (Na 2 CO 3 ) in solid state sintering process followed by quenching in air at 1000 degree Celsius. The paste was aging in simulated body fluid (SBF) for 0.5, 1, 3, 6, 12, 24, 48 hrs, 3, 7 and 14 days. The morphological investigation indicated the formation of apatite crystal were first growth after 24 hours. The obvious growth of apatite crystal was shown at 3 days. The obvious growth of apatite crystal was shown in 7 and 14 days indicated the prediction of paste would have rapid reaction with bone after implantation. (author)

Hemodialysis for near-fatal sodium phosphate toxicity in a child receiving sodium phosphate enemas.

Science.gov (United States)

Becknell, Brian; Smoyer, William E; O'Brien, Nicole F

2014-11-01

This study aimed to demonstrate the importance of considering hemodialysis as a treatment option in the management of sodium phosphate toxicity. This is a case report of a 4-year-old who presented to the emergency department with shock, decreased mental status, seizures, and tetany due to sodium phosphate toxicity from sodium phosphate enemas. Traditional management of hyperphosphatemia with aggressive hydration and diuretics was insufficient to reverse the hemodynamic and neurological abnormalities in this child. This is the first report of the use of hemodialysis in a child without preexisting renal failure for the successful management of near-fatal sodium phosphate toxicity. Hemodialysis can safely be used as an adjunctive therapy in sodium phosphate toxicity to rapidly reduce serum phosphate levels and increase serum calcium levels in children not responding to conventional management.

Spinels of Variscan olivine hornblendites related to the Montnegre granitoids revisited (NE Spain): petrogenetic evidence of mafic magma mixing

Energy Technology Data Exchange (ETDEWEB)

Galán, G.; Enrique, P.; Butjosa, L.; Fernández-Roig, L.

2017-07-01

Olivine hornblendites (cortlandtites) form part of the Montnegre mafic complex related to late-Variscan I-type granitoids in the Catalan Coastal Ranges. Two generations of spinel are present in these hornblendites: Spl1 forms euhedral crystals included in both olivine and Spl2. Spl2 forms euhedral to anhedral crystals associated with phlogopite and fibrous colourless amphibole forming pseudomorphs after olivine. Compositions of Spl1 are picotite-Al chromite (Fe#: 77.78-66.60; Cr#: 30.12-52.22; Fe3+/R3+: 6.99-21.89; 0.10< TiO2%< 0.62). Compositions of Spl2 are pleonaste (Fe#: 37.86-52.12; Cr#: 1.00-15.45; Fe3+/R3+: 0.31-5.21; TiO2% <0.10%). The two types of spinel follow a CrAl trend, mainly due to the substitution (Fe2+)-1Cr-1= MgAl, which is interpreted as the result of mixing between two different mantle-derived melts. The compositions of early Spl1 crystals included in olivine are characteristic of Al-rich basalts. More aluminous Spl2 would result from reaction of olivine with a less evolved, Al and K-rich mantle-derived melt after new refilling of the magma chamber or channel. As a whole, spinels from similar examples of Variscan olivine hronblendites also follow a CrAl trend with high Fe# and starting at higher Cr# than other trends of this type. Cr# heterogeneity in the early spinels from these Variscan hornblendites would be inherited from the variable Al content of the mafic melts involved in their genesis.

Syndeformation Chrome Spinels Inclusions in the Plastically Deformed Olivine Aggregates (Kraka Ophiolites, the Southern Urals

Directory of Open Access Journals (Sweden)

D. E. Saveliev

2015-12-01

Full Text Available This article presents the results of structural, petrographic, mineralogical and chemical studies of dunite veinlets in spinel peridotite from the Kraka ophiolites. It is demonstrated that plastic deformation of polycrystalline olivine, which form dunite, was accompanied by precipitation of impurities (aluminum and chrome as newly formed chrome spinels. The thinnest acicular inclusions of 0.3-0.5 micron thick are aligned in olivine grains along [010] axis. Bigger elongated irregular chrome spinel grains usually occur along grain and sub-grain olivine boundaries, and, occasionally, inside the grains along [100] axis. Alteration from the fine xenomorphic grains of chrome spinels to the bigger idiomorphic crystals was observed. Analogically to dynamic ageing (dispersion hardening in metals, the structural and chemical alterations in dunites are interpreted as deformation induced segregation of impurities. It is suggested that the euhedral chrome spinel grains typical for ophiolitic dunites were formed by coalescence and spheroidization. This process may be a key factor in the formation of ophiolitic chrome ore deposits.

Constraining the timescale of magma stagnation beneath Mauna Kea volcano, Hawaii,using diffusion profiles in olivine phenocrysts

Science.gov (United States)

Bloch, E. M.; Ganguly, J.

2009-12-01

Fe-Mg diffusion profiles have been measured in olivine xenocrysts within alkalic basalts in order to constrain the timescales of magma stagnation beneath Mauna Kea volcano, Hawaii. It has been suggested that during the main tholeiitic shield-building stage, and postshield eruptive stages of Mauna Kea, magmas were stalled and stagnated near the Moho, at a depth of ~15 km. Evidence in support of this hypothesis comes from cumulates formed by gravity-settling and in situ crystallization within magma chambers (Fodor and Galar, 1997), and from clinopyroxene-wholerock thermobarometry on Hamakua basalts (Putirka, in press). The cumulates represent a ‘fossil’ magma chamber which formed primarily from tholeiitic basalts; during the later capping-lava stage of Mauna Kea, alkalic basalts tore off chunks of these cumulates during ascent to the surface. We have measured several diffusion profiles in olivine xenocrysts from a single basalt sample. Because these xenocrysts have homogenous core compositions identical to a neighboring dunite cumulate, and because they are much larger and texturally distinct from compositionally dissimilar olivine phenocrysts, they are interpreted to be cumulate olivines which were dislodged during magma recharge/mixing in the stagnation zone. Although the orientations of the phenocrysts are not yet known, the diffusion profiles have been fit using diffusion coefficients parallel to the c and a crystallographic axes (i.e. minimum and maximum values). Modeling diffusion profiles yields ∫Ddt ≤4.5 x 10-5 cm2. Assuming that the xenocrysts were broken off from the cumulate immediately when the magma chamber was recharged, it is possible to calculate the maximum stagnation time of the basalts. Thus, the retrieved ∫Ddt value yields a maximum stagnation time of ~0.7 years. References: Fodor RV, Galar, PA (1997). A View into the Subsurface of Mauna Kea Volcano, Hawaii: Crystallization Processes Interpreted through the Petrology and Petrography of

Rolling stones. Fast weathering of olivine in shallow seas for cost-effective CO2 capture and mitigation of global warming and ocean acidification

Energy Technology Data Exchange (ETDEWEB)

Schuiling, R.D.; De Boer, P.L. [Department of Earth Sciences, Utrecht University, P.O. Box 80.021, 3508TA Utrecht (Netherlands)

2011-07-01

Human CO2 emissions may drive the Earth into a next greenhouse state. They can be mitigated by accelerating weathering of natural rock under the uptake of CO2. We disprove the paradigm that olivine weathering in nature would be a slow process, and show that it is not needed to mill olivine to very fine, 10 {mu}m-size grains in order to arrive at a complete dissolution within 1-2 year. In high-energy shallow marine environments olivine grains and reaction products on the grain surfaces, that otherwise would greatly retard the reaction, are abraded so that the chemical reaction is much accelerated. When kept in motion even large olivine grains rubbing and bumping against each other quickly produce fine clay- and silt-sized olivine particles that show a fast chemical reaction. Spreading of olivine in the world's 2% most energetic shelf seas can compensate a year's global CO2 emissions and counteract ocean acidification against a price well below that of carbon credits.

Oxygen isotopic composition of relict olivine grains in cosmic spherules: Links to chondrules from carbonaceous chondrites

Digital Repository Service at National Institute of Oceanography (India)

Rudraswami, N.G.; ShyamPrasad, M.; Nagashima, K.; Jones, R.H.

aluminium rich inclusions (CAIs), amoeboid olivine aggregates (AOAs), and some porphyritic chondrules from carbonaceous chondrites. These grains appear to have recorded the initial oxygen isotopic composition of the inner solar nebula. Three olivine... to the major components of meteorites such as chondrules and calcium-aluminium-rich inclusions (CAIs). CAIs, the first solar system objects in the solar nebula, are formed by condensation of refractory minerals at high temperatures. They are 16O...

Densification and Grain Growth in Polycrystalline Olivine Rocks Synthesized By Evacuated Hot-Pressing

Science.gov (United States)

Meyers, C. D.; Kohlstedt, D. L.; Zimmerman, M. E.

2017-12-01

Experiments on laboratory-synthesized olivine-rich rocks form the starting material for many investigations of physical processes in the Earth's upper mantle (e.g., creep behavior, ionic diffusion, and grain growth). Typically, a fit of a constitutive law to experimental data provides a description of the kinetics of a process needed to extrapolate across several orders of magnitude from laboratory to geological timescales. Although grain-size is a critical parameter in determining physical properties such as viscosity, broad disagreement persists amongst the results of various studies of grain growth kinetics in olivine-rich rocks. Small amounts of impurities or porosity dramatically affect the kinetics of grain growth. In this study, we developed an improved method for densifying olivine-rich rocks fabricated from powdered, gem-quality single crystals that involves evacuating the pore space, with the aim of refining measurements of the kinetics of mantle materials. In previous studies, olivine powders were sealed in a metal can and hydrostatically annealed at roughly 300 MPa and 1250 °C. These samples, which appear opaque and milky-green, typically retain a small amount of porosity. Consequently, when annealed at 1 atm, extensive pore growth occurs, inhibiting grain growth. In addition, Fourier-transform infrared and confocal Raman spectroscopy reveal absorption peaks characteristic of CO2 in the pores of conventionally hot-pressed material. To avoid trapping of adsorbed contaminants, we developed an evacuated hot-pressing method, wherein the pore space of powder compacts is vented to vacuum during heating and pressurization. This method produces a highly dense, green-tinted, transparent material. No CO2 absorptions peaks exist in evacuated hot-pressed material. When reheated to annealing temperatures at 1 atm, the evacuated hot-pressed material undergoes limited pore growth and dramatically enhanced grain-growth rates. High-strain deformation experiments on

Carbon Sequestration in Olivine and Basalt Powder Packed Beds.

Science.gov (United States)

Xiong, Wei; Wells, Rachel K; Giammar, Daniel E

2017-02-21

Fractures and pores in basalt could provide substantial pore volume and surface area of reactive minerals for carbonate mineral formation in geologic carbon sequestration. In many fractures solute transport will be limited to diffusion, and opposing chemical gradients that form as a result of concentration differences can lead to spatial distribution of silicate mineral dissolution and carbonate mineral precipitation. Glass tubes packed with grains of olivine or basalt with different grain sizes and compositions were used to explore the identity and spatial distribution of carbonate minerals that form in dead-end one-dimensional diffusion-limited zones that are connected to a larger reservoir of water in equilibrium with 100 bar CO 2 at 100 °C. Magnesite formed in experiments with olivine, and Mg- and Ca-bearing siderite formed in experiments with flood basalt. The spatial distribution of carbonates varied between powder packed beds with different powder sizes. Packed beds of basalt powder with large specific surface areas sequestered more carbon per unit basalt mass than powder with low surface area. The spatial location and extent of carbonate mineral formation can influence the overall ability of fractured basalt to sequester carbon.

Surface Modification of LiMn2O4 for Lithium Batteries by Nanostructured LiFePO4 Phosphate

Directory of Open Access Journals (Sweden)

B. Sadeghi

2012-01-01

Full Text Available LiMn2O4 spinel cathode materials have been successfully synthesized by solid-state reaction. Surface of these particles was modified by nanostructured LiFePO4 via sol gel dip coating method. Synthesized products were characterized by thermally analyzed thermogravimetric and differential thermal analysis (TG/DTA, X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, and energy dispersive X-ray spectroscopy (EDX. The results of electrochemical tests showed that the charge/discharge capacities improved and charge retention of battery enhanced. This improved electrochemical performance is caused by LiFePO4 phosphate layer on surfaces of LiMn2O4 cathode particles.

Prevalence of the Ancient Wood-Ljungdahl Pathway in a Subseafloor Olivine Community

Science.gov (United States)

Smith, A. R.; Mueller, R.; Fisk, M. R.; Mason, O. U.; Popa, R.; Kieft, B.; Colwell, F. S.

2018-05-01

The ancient Wood-Ljungdahl pathway used for biosynthesis and energy generation was found to be the predominant metabolic pathway in a microbial community from olivine grains incubated in the Juan de Fuca subseafloor aquifer.

Magma transport and olivine crystallization depths in Kīlauea's east rift zone inferred from experimentally rehomogenized melt inclusions

Science.gov (United States)

Tuohy, Robin M.; Wallace, Paul J.; Loewen, Matthew W.; Swanson, Donald A.; Kent, Adam J. R.

2016-07-01

Concentrations of H2O and CO2 in olivine-hosted melt inclusions can be used to estimate crystallization depths for the olivine host. However, the original dissolved CO2 concentration of melt inclusions at the time of trapping can be difficult to measure directly because in many cases substantial CO2 is transferred to shrinkage bubbles that form during post-entrapment cooling and crystallization. To investigate this problem, we heated olivine from the 1959 Kīlauea Iki and 1960 Kapoho (Hawai'i) eruptions in a 1-atm furnace to temperatures above the melt inclusion trapping temperature to redissolve the CO2 in shrinkage bubbles. The measured CO2 concentrations of the experimentally rehomogenized inclusions (⩽590 ppm for Kīlauea Iki [n = 10]; ⩽880 ppm for Kapoho, with one inclusion at 1863 ppm [n = 38]) overlap with values for naturally quenched inclusions from the same samples, but experimentally rehomogenized inclusions have higher within-sample median CO2 values than naturally quenched inclusions, indicating at least partial dissolution of CO2 from the vapor bubble during heating. Comparison of our data with predictions from modeling of vapor bubble formation and published Raman data on the density of CO2 in the vapor bubbles suggests that 55-85% of the dissolved CO2 in the melt inclusions at the time of trapping was lost to post-entrapment shrinkage bubbles. Our results combined with the Raman data demonstrate that olivine from the early part of the Kīlauea Iki eruption crystallized at <6 km depth, with the majority of olivine in the 1-3 km depth range. These depths are consistent with the interpretation that the Kīlauea Iki magma was supplied from Kīlauea's summit magma reservoir (∼2-5 km depth). In contrast, olivine from Kapoho, which was the rift zone extension of the Kīlauea Iki eruption, crystallized over a much wider range of depths (∼1-16 km). The wider depth range requires magma transport during the Kapoho eruption from deep beneath the summit

Sintering mantle mineral aggregates with submicron grains: examples of olivine and clinopyroxene

Science.gov (United States)

Tsubokawa, Y.; Ishikawa, M.

2017-12-01

Physical property of the major mantle minerals play an important role in the dynamic behavior of the Earth's mantle. Recently, it has been found that nano- to sub-micron scale frictional processes might control faulting processes and earthquake instability, and ultrafine-grained mineral aggregates thus have attracted the growing interest. Here we investigated a method for preparing polycrystalline clinoyproxene and polycrystalline olivine with grain size of sub-micron scale from natural crystals, two main constituents of the upper mantle. Nano-sized powders of both minerals are sintered under argon flow at temperatures ranging from 1130-1350 °C for 0.5-20 h. After sintering at 1180 °C and 1300 °C, we successfully fabricated polycrystalline clinopyroxene and polycrystalline olivine with grain size of physical properties of Earth's mantle.

Multi-scale three-dimensional characterization of iron particles in dusty olivine: Implications for paleomagnetism of chondritic meteorites

DEFF Research Database (Denmark)

Einsle, Joshua F.; Harrison, Richard J.; Kasama, Takeshi

2016-01-01

Dusty olivine (olivine containing multiple sub-micrometer inclusions of metallic iron) in chondritic meteorites is considered an ideal carrier of paleomagnetic remanence, capable of maintaining a faithful record of pre-accretionary magnetization acquired during chondrule formation. Here we show how......-dimensional (3D) volume reconstruction of a dusty olivine grain, obtained by selective milling through a region of interest in a series of sequential 20 nm slices, which are then imaged using scanning electron microscopy. The data provide a quantitative description of the iron particle ensemble, including...... axes of the particles and the remanence vector imparted in different fields. Although the orientation of the vortex core is determined largely by the ellipsoidal geometry (i.e., parallel to the major axis for prolate ellipsoids and parallel to the minor axis for oblate ellipsoids), the core...

Synthesis and stability of α-tricalcium phosphate doped with dicalcium silicate in the system Ca3(PO4)2-Ca2SiO4

International Nuclear Information System (INIS)

Martinez, I.M.; Velasquez, P.A.; De Aza, P.N.

2010-01-01

The aim of this study was to synthesize materials of α-tricalcium phosphate doped with small amounts of dicalcium silicate, by solid state reaction, at high temperature and slow cooling to room temperature. The obtained materials were characterized by X-ray diffraction, Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy, showing that there is a region between 0.5 and 4.0 wt.% of dicalcium silicate where solid solution α-tricalcium phosphate (α-TCPss) is stable to room temperature.

Meningococcal X polysaccharide quantification by high-performance anion-exchange chromatography using synthetic N-acetylglucosamine-4-phosphate as standard.

Science.gov (United States)

Micoli, F; Adamo, R; Proietti, D; Gavini, M; Romano, M R; MacLennan, C A; Costantino, P; Berti, F

2013-11-15

A method for meningococcal X (MenX) polysaccharide quantification by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) is described. The polysaccharide is hydrolyzed by strong acidic treatment, and the peak of glucosamine-4-phosphate (4P-GlcN) is detected and measured after chromatography. In the selected conditions of hydrolysis, 4P-GlcN is the prevalent species formed, with GlcN detected for less than 5% in moles. As standard for the analysis, the monomeric unit of MenX polysaccharide, N-acetylglucosamine-4-phosphate (4P-GlcNAc), was used. This method for MenX quantification is highly selective and sensitive, and it constitutes an important analytical tool for the development of a conjugate vaccine against MenX. Copyright © 2013 Elsevier Inc. All rights reserved.

Crystallization history of enriched shergottites from Fe and Mg isotope fractionation in olivine megacrysts

Science.gov (United States)

Collinet, Max; Charlier, Bernard; Namur, Olivier; Oeser, Martin; Médard, Etienne; Weyer, Stefan

2017-06-01

Martian meteorites are the only samples available from the surface of Mars. Among them, olivine-phyric shergottites are basalts containing large zoned olivine crystals with highly magnesian cores (Fo 70-85) and rims richer in Fe (Fo 45-60). The Northwest Africa 1068 meteorite is one of the most primitive "enriched" shergottites (high initial 87Sr/86Sr and low initial ε143Nd). It contains olivine crystals as magnesian as Fo 77 and is a major source of information to constrain the composition of the parental melt, the composition and depth of the mantle source, and the cooling and crystallization history of one of the younger magmatic events on Mars (∼180 Ma). In this study, Fe-Mg isotope profiles analyzed in situ by femtosecond-laser ablation MC-ICP-MS are combined with compositional profiles of major and trace elements in olivine megacrysts. The cores of olivine megacrysts are enriched in light Fe isotopes (δ56FeIRMM-14 = -0.6 to -0.9‰) and heavy Mg isotopes (δ26MgDSM-3 = 0-0.2‰) relative to megacryst rims and to the bulk martian isotopic composition (δ56Fe = 0 ± 0.05‰, δ26Mg = -0.27 ± 0.04‰). The flat forsterite profiles of megacryst cores associated with anti-correlated fractionation of Fe-Mg isotopes indicate that these elements have been rehomogenized by diffusion at high temperature. We present a 1-D model of simultaneous diffusion and crystal growth that reproduces the observed element and isotope profiles. The simulation results suggest that the cooling rate during megacryst core crystallization was slow (43 ± 21 °C/year), and consistent with pooling in a deep crustal magma chamber. The megacryst rims then crystallized 1-2 orders of magnitude faster during magma transport toward the shallower site of final emplacement. Megacryst cores had a forsterite content 3.2 ± 1.5 mol% higher than their current composition and some were in equilibrium with the whole-rock composition of NWA 1068 (Fo 80 ± 1.5). NWA 1068 composition is thus close to a

Sonochemical precipitation of amorphous uranium phosphates from trialkyl phosphate solutions and their thermal conversion to UP2O7

Czech Academy of Sciences Publication Activity Database

Doroshenko, I.; Žurková, J.; Moravec, Z.; Bezdička, Petr; Pinkas, J.

2015-01-01

Roč. 26, SEP (2015), s. 157-162 ISSN 1350-4177 Institutional support: RVO:61388980 Keywords : Uranium * Phosphates * Sonochemistry * Nuclear waste * Trimethyl phosphate * Triethyl phosphate Subject RIV: CA - Inorganic Chemistry Impact factor: 4.556, year: 2015

PHOSPHATE CRYSTALLURIA IN VARIOUS FORMS OF UROLITHIASIS AND POSSIBILITIES OF ITS PROGNOSTICATION IN PATIENTS WITH PHOSPHATE STONES

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O. V. Konstantinova

2017-01-01

Full Text Available Purpose. Definition of types of crystalluria in various forms of urolithiasis and biochemical signs of phosphate crystals in the urine, while phosphate urolithiasis (infectious origin.Patients and methods. The study involved 144 patients with recurrent urolithiasis — 75 women and 69 men. Of these, 46 — diagnosed calculi with uric acid, 44 — calcium oxalate or mixed with a prevalence of calcium oxalate, in 54 — phosphate rocks (carbonate-apatite and/or struvite. The age of patients ranged from 21 to 74 years. 93 people have been under long-term, within 2–15 years, outpatient observation. The examination included the collection of anamnesis, general and microbiological analysis of urine, biochemical blood serum and urine on 10 indicators, reflecting renal function, state of the protein, water and electrolyte metabolism, uric acid metabolism, the chemical composition of the stone analysis.Results. It was found that in patients with calcium oxalate stones phosphaturia has been diagnosed in 2% of cases. And, along with calcium phosphate crystals they had oxalate crystals. In patients with phosphate urolithiasis phosphaturia observed in 96% of patients, in two patients (4% they determined except phosphates also oxalate salt in urine sediment. Patients with phosphate urolithiasis at occurrence of phosphate crystalluria have metabolic state changes: increased serum uric acid concentration from 0.322 ± 0.009 to 0.367 ± 0.018 mmol/l daily renal excretion of inorganic phosphate 23.94 ± 2.93 mmol/day to 32.12 ± 4.39 mmol/day, and reduced total calcium content in urine 6.61 ± 0.94 mmol/day to 3.37 ± 0.89 mmol/day. The results led to the following conclusion.Conclusion. Biochemical signs of occurrence of phosphate crystalluria in patients with stones of infectious origin can be: the approaching level of excretion in the urine of inorganic phosphates to 32,12 ± 4,39 mmol/day, serum uric acid concentration to 0,367 ± 0,018 mmol/l, and the

Space Weathering Evolution on Airless Bodies - Laboratory Simulations with Olivine

Czech Academy of Sciences Publication Activity Database

Kohout, Tomáš; Čuda, J.; Bradley, T.; Britt, D.; Filip, J.; Tuček, J.; Malina, O.; Kašlík, J.; Šišková, K.; Zbořil, R.

2013-01-01

Roč. 45, č. 9 (2013), s. 25-26 ISSN 0002-7537. [Annual meeting of the Division for Planetary Sciences of the American Astronomical Society /45./. 06.10.2013-11.10.2013, Denver] Institutional support: RVO:67985831 Keywords : space weathering * asteroid * Moon * olivine Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics http://aas.org/files/resources/dps_abstract_book.pdf

Oxysterol-binding Protein Activation at Endoplasmic Reticulum-Golgi Contact Sites Reorganizes Phosphatidylinositol 4-Phosphate Pools*

OpenAIRE

Goto, Asako; Charman, Mark; Ridgway, Neale D.

2015-01-01

Oxysterol-binding protein (OSBP) exchanges cholesterol and phosphatidylinositol 4-phosphate (PI-4P) at contact sites between the endoplasmic reticulum (ER) and the trans-Golgi/trans-Golgi network. 25-Hydroxycholesterol (25OH) competitively inhibits this exchange reaction in vitro and causes the constitutive localization of OSBP at the ER/Golgi interface and PI-4P-dependent recruitment of ceramide transfer protein (CERT) for sphingomyelin synthesis. We used PI-4P probes and mass analysis to de...

Olivine-melt relationships and syneruptive redox variations in the 1959 eruption of K$\\bar{i}$lauea Volcano as revealed by XANES

Energy Technology Data Exchange (ETDEWEB)

Helz, R. T.; Cottrell, E.; Brounce, M. N.; Kelley, K. A.

2017-03-01

The 1959 summit eruption of K$\\bar{i}$lauea Volcano exhibited high lava fountains of gas-rich, primitive magma, containing olivine + chromian spinel in highly vesicular brown glass. Microprobe analysis of these samples shows that euhedral rims on olivine phenocrysts, in direct contact with glass, vary significantly in forsterite (Fo) content, at constant major-element melt composition, as do unzoned groundmass olivine crystals. Ferric/total iron (Fe+ 3/FeT)ratios for matrix and interstitial glasses, plus olivine-hosted glass inclusions in eight 1959 scoria samples have been determined by micro X-ray absorption near-edge structure spectroscopy (μ-XANES). These data show that much of the variation in Fo content reflects variation in oxidation state of iron in the melt, which varies with sulfur concentration in the glass and (locally) with proximity to scoria edges in contact with air. Data for 24 olivine-melt pairs in the better-equilibrated samples from later in the eruption show KD averaging 0.280 ± 0.03 for the exchange of Fe and Mg between olivine and melt, somewhat displaced from the value of 0.30 ± 0.03 given by Roeder and Emslie (1970). This may reflect the low SiO2 content of the 1959 magmas, which is lower than that in most K$\\bar{i}$lauea tholeiites. More broadly, we show the potential of μ-XANES and electron microprobe to revisit and refine the value of KD in natural systems.

Compositional controls on spinel clouding and garnet formation in plagioclase of olivine metagabbros, Adirondack Mountains, New York

Science.gov (United States)

McLelland, J.M.; Whitney, P.R.

1980-01-01

Olivine metagabbros from the Adirondacks usually contain both clear and spinel-clouded plagioclase, as well as garnet. The latter occurs primarily as the outer rim of coronas surrounding olivine and pyroxene, and less commonly as lamellae or isolated grains within plagioclase. The formation of garnet and metamorphic spinel is dependent upon the anorthite content of the plagioclase. Plagioclase more sodic than An38??2 does not exhibit spinel clouding, and garnet rarely occurs in contact with plagioclase more albitic than An36??4. As a result of these compositional controls, the distribution of spinel and garnet mimics and visually enhances original igneous zoning in plagioclase. Most features of the arrangement of clear (unclouded) plagioclase, including the shells or moats of clear plagioclase which frequently occur inside the garnet rims of coronas, can be explained on the basis of igneous zoning. The form and distribution of the clear zones may also be affected by the metamorphic reactions which have produced the coronas, and by redistribution of plagioclase in response to local volume changes during metamorphism. ?? 1980 Springer-Verlag.

Reply to comment by Nozaka (2014) on ;Dehydration breakdown of antigorite and the formation of B-type olivine CPO;

Science.gov (United States)

Nagaya, Takayoshi; Wallis, Simon R.; Kobayashi, Hiroaki; Michibayashi, Katsuyoshi; Mizukami, Tomoyuki; Seto, Yusuke; Miyake, Akira; Matsumoto, Megumi

2014-12-01

We would like to thank Dr. Nozaka for his interest in our work and also for supplying some of the crystal orientation data that we used in our study. He presents a detailed discussion of differences in interpretation between our two studies. The main difference is whether the strong B-type olivine CPO developed as a result of topotactic static growth after breakdown of antigorite (Nagaya et al., 2014) or if it developed due to homoepitaxial growth on a limited number of olivine grains that already showed a general B-type CPO (Nozaka, 2014). In both of our studies static growth of olivine due to the breakdown of antigorite is key in the strengthening or formation of B-type olivine CPO. This conclusion has potentially far reaching implications for the interpretation of mantle seismic anisotropy in subduction zones and is the most important take home message. However, the details of interpretation are also important. In our reply, we focus on what we consider to be the 5 main points of disagreement. We refer to Fig. 1 to explain different microstructural domains.

Comment on ;Dehydration breakdown of antigorite and the formation of B-type olivine CPO; by Nagaya et al. (2014)

Science.gov (United States)

Nozaka, Toshio

2014-12-01

Recently, Nagaya et al. (2014) have reported the B-type crystallographic preferred orientation (CPO) of olivine in thermally metamorphosed serpentinites from the Happo ultramafic complex, central Japan, and interpreted the CPO as a result of topotactic growth of olivine after antigorite. Their conclusions require the reconsideration of the genesis of B-type olivine CPO, which is generally believed to be formed by plastic deformation of hydrous peridotites, and could have an impact on structural models of supra-subduction zones. I appreciate the detailed observations by Nagaya et al. (2014) but have to point out that they committed significant misinterpretation of facts and failed to show robust evidence and rationale for their argument.

Translocation of metal phosphate via the phosphate inorganic transport system of Escherichia coli

NARCIS (Netherlands)

van Veen, H.W; Abee, T.; Kortstee, G.J J; Konings, W.N; Zehnder, A.J B

1994-01-01

P-i transport via the phosphate inorganic transport system (Pit) of Escherichia coil was studied in natural and artificial membranes. P-i uptake via Pit is dependent on the presence of divalent cations, like Mg2+, Ca2+, Co2+, or Mn2+, which form a soluble, neutral metal phosphate (MeHPO(4)) complex.

Stimulation of Eryptosis by Combretastatin A4 Phosphate Disodium (CA4P

Directory of Open Access Journals (Sweden)

Elena Signoretto

2016-03-01

Full Text Available Background/Aims: Combretastatin A4 phosphate disodium (CA4P is utilized for the treatment of malignancy. The substance has previously been shown to trigger suicidal cell death or apoptosis. Similar to apoptosis of nucleated cells, erythrocytes may enter suicidal death or eryptosis, characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Stimulators of eryptosis include increase of cytosolic Ca2+ activity ([Ca2+]i, ceramide, oxidative stress and ATP depletion. The present study explored, whether CA4P induces eryptosis and, if so, to gain insight into mechanisms involved. Methods: Flow cytometry has been employed to estimate phosphatidylserine exposure at the cell surface from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, reactive oxygen species (ROS abundance from DCF fluorescence, glutathione (GSH abundance from CMF fluorescence and ceramide abundance from fluorescent antibodies. In addition cytosolic ATP levels were quantified utilizing a luciferin-luciferase-based assay and hemolysis was estimated from hemoglobin concentration in the supernatant. Results: A 48 hours exposure of human erythrocytes to CA4P (≥ 50 µM significantly increased the percentage of annexin-V-binding cells and significantly decreased forward scatter. CA4P did not appreciably increase hemolysis. Hundred µM CA4P significantly increased Fluo3-fluorescence. The effect of CA4P (100 µM on annexin-V-binding was significantly blunted, but not abolished, by removal of extracellular Ca2+. CA4P (≥ 50 µM significantly decreased GSH abundance and ATP levels but did not significantly increase ROS or ceramide. Conclusions: CA4P triggers cell shrinkage and phospholipid scrambling of the erythrocyte cell membrane, an effect at least in part due to entry of extracellular Ca2+ and energy depletion.

Untypical (VOPO4) Layer in Vanadyl Phosphates with Variant Interlayer Gap of Double - Tiered Template

Czech Academy of Sciences Publication Activity Database

Yang, Y.-Ch.; Lai, Y-Ch.; Salazar, J.R.; Zima, Vítězslav; Lii, K-H.; Wang, S.-L.

2010-01-01

Roč. 49, č. 13 (2010), s. 6196-6202 ISSN 0020-1669 R&D Projects: GA ČR GA203/08/0208 Institutional research plan: CEZ:AV0Z40500505 Keywords : vanadyl * phosphate * structure Subject RIV: CA - Inorganic Chemistry Impact factor: 4.326, year: 2010

Size effects in olivine control strength in low-temperature plasticity regime

Science.gov (United States)

Kumamoto, K. M.; Thom, C.; Wallis, D.; Hansen, L. N.; Armstrong, D. E. J.; Goldsby, D. L.; Warren, J. M.; Wilkinson, A. J.

2017-12-01

The strength of the lithospheric mantle during deformation by low-temperature plasticity controls a range of geological phenomena, including lithospheric-scale strain localization, the evolution of friction on deep seismogenic faults, and the flexure of tectonic plates. However, constraints on the strength of olivine in this deformation regime are difficult to obtain from conventional rock-deformation experiments, and previous results vary considerably. We demonstrate via nanoindentation that the strength of olivine in the low-temperature plasticity regime is dependent on the length-scale of the test, with experiments on smaller volumes of material exhibiting larger yield stresses. This "size effect" has previously been explained in engineering materials as a result of the role of strain gradients and associated geometrically necessary dislocations in modifying plastic behavior. The Hall-Petch effect, in which a material with a small grain size exhibits a higher strength than one with a large grain size, is thought to arise from the same mechanism. The presence of a size effect resolves discrepancies among previous experimental measurements of olivine, which were either conducted using indentation methods or were conducted on polycrystalline samples with small grain sizes. An analysis of different low-temperature plasticity flow laws extrapolated to room temperature reveals a power-law relationship between length-scale (grain size for polycrystalline deformation and contact radius for indentation tests) and yield strength. This suggests that data from samples with large inherent length scales best represent the plastic strength of the coarse-grained lithospheric mantle. Additionally, the plastic deformation of nanometer- to micrometer-sized asperities on fault surfaces may control the evolution of fault roughness due to their size-dependent strength.

Effect of oxygen fugacity on OH dissolution in olivine under peridotite-saturated conditions: An experimental study at 1.5-7 GPa and 1100-1300 °C

Science.gov (United States)

Yang, Xiaozhi

2016-01-01

The dissolution of OH in olivine by experimental studies at simulated conditions has attracted increasing interest over the past three decades, and the influence of pressure, temperature and composition has been relatively well constrained. Oxygen fugacity is highly heterogeneous in the upper mantle, on both temporal and spatial scales, and is an important parameter in characterizing many chemical and physical processes in the mantle. However, less attention has been devoted to the effect of oxygen fugacity on OH dissolution in olivine, and the only few available reports on this topic have led to significant inconsistency and debate. In this study, the correlation between oxygen fugacity and OH solubility in Fe-bearing olivine has been systematically investigated by conducting experiments at 1.5-7 GPa and 1100-1300 °C and under peridotite- and fluid-saturated conditions, with natural gem-quality olivine single crystals and fresh peridotite xenoliths as starting materials and with oxygen fugacity controlled by the Fe-FeO, Ni-NiO and Fe2O3-Fe3O4 oxygen buffer pairs. The water concentrations were determined by polarized analyses using a Fourier-transform infrared spectroscopy. The results show that, at all the experimental conditions, the OH bands at both high frequency (∼3650-3450 cm-1) and low frequency (∼3450-3100 cm-1) are prominent. The intensity of OH bands at ∼3355 and 3325 cm-1 increases positively with oxygen fugacity, suggesting a dominant role of Fe3+ in their incorporation. Under otherwise identical conditions, the water content is gradually enhanced with increasing pressure, temperature or oxygen fugacity. The effect of oxygen fugacity on the enhancement of OH solubility appears not sensitive to temperature (1100-1300 °C) at a given pressure, but becomes progressively stronger with increasing pressure from 1.5 to 7 GPa given the temperature. Relative to oxygen fugacity buffers, the OH solubility is on average increased by ∼50% between Fe-FeO and

High-capacity cathodes for lithium-ion batteries from nanostructured LiFePO4 synthesized by highly-flexible and scalable flame spray pyrolysis

Science.gov (United States)

Hamid, N. A.; Wennig, S.; Hardt, S.; Heinzel, A.; Schulz, C.; Wiggers, H.

2012-10-01

Olivine, LiFePO4 is a promising cathode material for lithium-ion batteries due to its low cost, environmental acceptability and high stability. Its low electric conductivity prevented it for a long time from being used in large-scale applications. Decreasing its particle size along with carbon coating significantly improves electronic conductivity and lithium diffusion. With respect to the controlled formation of very small particles with large specific surface, gas-phase synthesis opens an economic and flexible route towards high-quality battery materials. Amorphous FePO4 was synthesized as precursor material for LiFePO4 by flame spray pyrolysis of a solution of iron acetylacetonate and tributyl phosphate in toluene. The pristine FePO4 with a specific surface from 126-218 m2 g-1 was post-processed to LiFePO4/C composite material via a solid-state reaction using Li2CO3 and glucose. The final olivine LiFePO4/C particles still showed a large specific surface of 24 m2 g-1 and were characterized using X-ray diffraction (XRD), electron microscopy, X-ray photoelectron spectrocopy (XPS) and elemental analysis. Electrochemical investigations of the final LiFePO4/C composites show reversible capacities of more than 145 mAh g-1 (about 115 mAh g-1 with respect to the total coating mass). The material supports high drain rates at 16 C while delivering 40 mAh g-1 and causes excellent cycle stability.

An Analytical Finite-Strain Parameterization for Texture Evolution in Deformed Olivine Polycrystals

Science.gov (United States)

Ribe, N. M.; Castelnau, O.

2017-12-01

Current methods for calculating the evolution of flow-induced seismic anisotropy in the upper mantle describe crystal preferred orientation (CPO) using ensembles of 103-104 individual grains, and are too computationally expensive to be used in three-dimensional time-dependent convection models. We propose a much faster method based on the hypothesis that CPO of olivine polycrystals is a unique function of the finite strain. Our goal is then to determine how the CPO depends on the ratios r12 and r23 of the axes of the finite strain ellipsoid and on the two independent ratios p12 and p23 of the strengths (critical resolved shear stresses) of the three independent slip systems of olivine. To do this, we introduce a new analytical representation of olivine CPO in terms of three `structured basis functions' (SBFs) Fs(g, r12, r23) (s = 1, 2, 3), where g is the set of three Eulerian angles that describe the orientation of a crystal lattice relative to an external reference frame. Each SBF represents the virtual CPO that would be produced by the action of only one of the slip systems of olivine, and can be determined analytically to within an unknown time-dependent amplitude. The amplitudes are then determined by fitting the SBFs to the predictions of the second-order self-consistent (SOSC) model of Ponte-Castaneda (2002). To implement the SBF representation, we express the orientation distribution function (ODF) f(g) of the polycrystal approximately as a linear superposition of SBFs with weighting coefficients Cs. Substituting the superposition into the general evolution equation for the ODF and minimizing the residual error, we find that the weighting coefficients Cs(t) satisfy coupled evolution equations of the form αisCs + βisCs + γs = 0 where the coefficients αis, βis and γs can be calculated in advance from the expressions for the SBFs. These equations are solved numerically for different values of p12 and p23, yielding numerical values of Cs(r12, r23, p12, p23

Phosphate control in dialysis

Directory of Open Access Journals (Sweden)

Cupisti A

2013-10-01

Full Text Available Adamasco Cupisti,1 Maurizio Gallieni,2 Maria Antonietta Rizzo,2 Stefania Caria,3 Mario Meola,4 Piergiorgio Bolasco31Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy; 2Nephrology and Dialysis Unit, San Carlo Borromeo Hospital, Milan, Italy; 3Territorial Department of Nephrology and Dialysis, ASL Cagliari, Italy; 4Sant'Anna School of Advanced Studies, University of Pisa, Pisa, ItalyAbstract: Prevention and correction of hyperphosphatemia is a major goal of chronic kidney disease–mineral and bone disorder (CKD–MBD management, achievable through avoidance of a positive phosphate balance. To this aim, optimal dialysis removal, careful use of phosphate binders, and dietary phosphate control are needed to optimize the control of phosphate balance in well-nourished patients on a standard three-times-a-week hemodialysis schedule. Using a mixed diffusive–convective hemodialysis tecniques, and increasing the number and/or the duration of dialysis tecniques are all measures able to enhance phosphorus (P mass removal through dialysis. However, dialytic removal does not equal the high P intake linked to the high dietary protein requirement of dialysis patients; hence, the use of intestinal P binders is mandatory to reduce P net intestinal absorption. Unfortunately, even a large dose of P binders is able to bind approximately 200–300 mg of P on a daily basis, so it is evident that their efficacy is limited in the case of an uncontrolled dietary P load. Hence, limitation of dietary P intake is needed to reach the goal of neutral phosphate balance in dialysis, coupled to an adequate protein intake. To this aim, patients should be informed and educated to avoid foods that are naturally rich in phosphate and also processed food with P-containing preservatives. In addition, patients should preferentially choose food with a low P-to-protein ratio. For example, patients could choose egg white or protein from a vegetable source

Synthesis, structures and properties of the new lithium cobalt(II) phosphate Li4Co(PO4)2

International Nuclear Information System (INIS)

Glaum, R.; Gerber, K.; Schulz-Dobrick, M.; Herklotz, M.; Scheiba, F.; Ehrenberg, H.

2012-01-01

α-Li 4 Co(PO 4 ) 2 has been synthesized and crystallized by solid-state reactions. The new phosphate crystallizes in the monoclinic system (P2 1 /a, Z=4, a=8.117(3) Å, b=10.303(8) Å, c=8.118(8) Å, β=104.36(8) Å) and is isotypic to α-Li 4 Zn(PO 4 ) 2 . The structure of α-Li 4 Co(PO 4 ) 2 has been determined from single-crystal X-ray diffraction data {R 1 =0.040, wR 2 =0.135, 2278 unique reflections with F o >4σ(F o )}. The crystal structure, which might be regarded as a superstructure of the wurtzite structure type, is build of layers of regular CoO 4 , PO 4 and Li1O 4 tetrahedra. Lithium atoms Li2, Li3 and Li4 are located between these layers. Thermal investigations by in-situ XRPD, DTA/TG and quenching experiments suggest decomposition followed by formation and phase transformation of Li 4 Co(PO 4 ) 2 : α-Li 4 Co(PO 4 ) 2 ⟹ 442°C β-Li 3 PO 4 +LiCoPO 4 ⇌ 773°C β-Li 4 Co(PO 4 ) 2 ⟹ quenchingto25°C α-Li 4 Co(PO 4 ) 2 According to HT-XRPD at θ=850°Cβ-Li 4 Co(PO 4 ) 2 (Pnma, Z=2, 10.3341(8) Å, b=6.5829(5) Å, c=5.0428(3) Å) is isostructural to γ-Li 3 PO 4 . The powder reflectance spectrum of α-Li 4 Co(PO 4 ) 2 shows the typical absorption bands for the tetrahedral chromophore [Co II O 4 ]. - Graphical abstract: The complex formation and decomposition behavior of Li 4 Co(PO 4 ) 2 with temperature has been elucidated. The crystal structure of its α-phase was determined from single crystal data, HT-XRPD allowed derivation of a structure model for the β-phase. Both modifications belong to the Li 3 PO 4 structure family. Highlights: ► Li 4 Co(PO 4 ) 2 exhibits complex thermal behavior. ► The new phosphate belongs to the Li 3 PO 4 structure family. ► A single-crystal structure analysis is provided for the metastable α-Li 4 Co(PO 4 ) 2 . ► From HT-XRPD data a cation distribution model is developed for β-Li 4 Co(PO 4 ) 2 . ► No electrochemical delithiation is observed up to 5 V.

Acid indium strontium phosphate SrIn2[PO3(OH)]4: synthesis and crystal structure

International Nuclear Information System (INIS)

Rusakov, D.A.; Bobylev, A.P.; Komissarova, L.N.; Filaretov, A.A.; Danilov, V.P.

2007-01-01

Acid indium-strontium phosphate SrIn 2 [PO 3 (OH)] 4 is synthesized and characterized. Crystal structure and lattice parameters ate determined. In atoms in SrIn 2 [PO 3 (OH)] 4 structure are in distorted InO 6 octahedrons and form with PO 3 (OH) tetrahedrons mixed paraskeleton {In 2 [PO 3 (OH)] 4 } 3∞ 2- with emptinesses occupied by big Sr 2+ cations. The compound is thermally stable up to 400 Deg C [ru

Availability of rock phosphate with low P content in some Albanian soil: use of /sup 32/PO/sub 4/

Energy Technology Data Exchange (ETDEWEB)

Fardeau, J C; Migadel, F; Gjermani, A; Malja, S

1983-10-01

The availability of a calcareous low P content rock phosphate (4,3% P) was measured. This Albanian ore was used, in pot experiments, on various local soils whose pH is situated between 4,9 to 7,5. This phosphate was labelled with /sup 32/P and /sup 45/Ca in a reactor. The residual effect of this fertilizer was deduced from the results of isotopic dilution kinetics of phosphate ions realized in soil-solution systems. The main results can be summarized as follows: 1. When the soil-water pH was higher than 6,1, the utilization coefficient of phosphorus was minus than 1%, even with 5,5 months. 2. The ratio of P and Ca derived from fertilizer and taken up by the crop is most generally different of those measured in the fertilizer. It depends on the soil constitution. 3. The analysis of isotopic dilution kinetics of phosphate ions shows that in the major part of these soils, whose fixing capacity is very high, the rock phosphate and also superphosphate at 230 kg P/sub 2/O/sub 5/.ha/sup -1/ rate does not increase available soil phosphorus; it is only with rates over 800 kg P/sub 2/O/sub 5/.ha/sup -1/ that this objective can be reached. These results explain again that the fixing capacity of soil for phosphorus is a characteristic more useful for fertilization technique than the available phosphorus quantity.

Chemical Analysis of Reaction Rims on Olivine Crystals in Natural Samples of Black Dacite Using Energy-Dispersive X-Ray Spectroscopy, Lassen Peak, CA.

Science.gov (United States)

Graham, N. A.

2014-12-01

Lassen Volcanic Center is the southernmost volcanic region in the Cascade volcanic arc formed by the Cascadia Subduction Zone. Lassen Peak last erupted in 1915 in an arc related event producing a black dacite material containing xenocrystic olivine grains with apparent orthopyroxene reaction rims. The reaction rims on these olivine grains are believed to have formed by reactions that ensued from a mixing/mingling event that occurred prior to eruption between the admixed mafic andesitic magma and a silicic dacite host material. Natural samples of the 1915 black dacite from Lassen Peak, CA were prepared into 15 polished thin sections and carbon coated for analysis using a FEI Quanta 250 Scanning Electron Microscope (SEM) to identify and measure mineral textures and disequilibrium reaction rims. Observed mineralogical textures related to magma mixing include biotite and amphibole grains with apparent dehydration/breakdown rims, pyroxene-rimmed quartz grains, high concentration of microlites in glass matrix, and pyroxene/amphibole reaction rims on olivine grains. Olivine dissolution is evidenced as increased iron concentration toward convolute edges of olivine grains as observed by Backscatter Electron (BSE) imagery and elemental mapping using NSS spectral imaging software. In an attempt to quantify the area of reaction rim growth on olivine grains within these samples, high-resolution BSE images of 30 different olivine grains were collected along with Energy-Dispersive X-Ray Spectroscopy (EDS) of different phases. Olivine cores and rims were extracted from BSE images using Photoshop and saved as separate image files. ImageJ software was used to calculate the area (μm2) of the core and rim of these grains. Average pyroxene reaction rim width for 30 grains was determined to be 11.68+/-1.65 μm. Rim widths of all 30 grains were averaged together to produce an overall average rim width for the Lassen Peak black dacite. By quantifying the reaction rims on olivine grains

Tracking the Martian Mantle Signature in Olivine-Hosted Melt Inclusions of Basaltic Shergottites Yamato 980459 and Tissint

Science.gov (United States)

Peters, T. J.; Simon, J. I.; Jones, J. H.; Usui, T.; Moriwaki, R.; Economos, R.; Schmitt, A.; McKeegan, K.

2014-01-01

The Martian shergottite meteorites are basaltic to lherzolitic igneous rocks that represent a period of relatively young mantle melting and volcanism, approximately 600-150 Ma (e.g. [1,2]). Their isotopic and elemental composition has provided important constraints on the accretion, evolution, structure and bulk composition of Mars. Measurements of the radiogenic isotope and trace element concentrations of the shergottite meteorite suite have identified two end-members; (1) incompatible trace element enriched, with radiogenic Sr and negative epsilon Nd-143, and (2) incompatible traceelement depleted, with non-radiogenic Sr and positive epsilon 143-Nd(e.g. [3-5]). The depleted component represents the shergottite martian mantle. The identity of the enriched component is subject to debate, and has been proposed to be either assimilated ancient martian crust [3] or from enriched domains in the martian mantle that may represent a late-stage magma ocean crystallization residue [4,5]. Olivine-phyric shergottites typically have the highest Mg# of the shergottite group and represent near-primitive melts having experienced minimal fractional crystallization or crystal accumulation [6]. Olivine-hosted melt inclusions (MI) in these shergottites represent the most chemically primitive components available to understand the nature of their source(s), melting processes in the martian mantle, and origin of enriched components. We present trace element compositions of olivine hosted melt inclusions in two depleted olivinephyric shergottites, Yamato 980459 (Y98) and Tissint (Fig. 1), and the mesostasis glass of Y98, using Secondary Ionization Mass Spectrometry (SIMS). We discuss our data in the context of understanding the nature and origin of the depleted martian mantle and the emergence of the enriched component.

Catalytic decomposition of biomass tars: Use of dolomite and untreated olivine

NARCIS (Netherlands)

Devi, L.; Ptasinski, K.J.; Janssen, F.J.J.G.; Paasen, van S.V.B.; Bergman, P.C.A.; Kiel, J.H.A.

2005-01-01

Although biomass is getting increased attention as a renewable energy source, one of the remaining problems still to be solved is the reduction of the high level of tar present in the product gas from gasification of biomass. The purpose of the present work is to study the activity of olivine and

31P-Nuclear Magnetic Resonance Determination of Phosphate Compartmentation in Leaves of Reproductive Soybeans (Glycine max L.) as Affected by Phosphate Nutrition 1

Science.gov (United States)

Lauer, Michael J.; Blevins, Dale G.; Sierzputowska-Gracz, Hanna

1989-01-01

Most leaf phosphorus is remobilized to the seed during reproductive development in soybean. We determined, using 31P-NMR, the effect phosphorus remobilization has on vacuolar inorganic phosphate pool size in soybean (Glycine max [L.] Merr.) leaves with respect to phosphorus nutrition and plant development. Phosphate compartmentation between cytoplasmic and vacuolar pools was observed and followed in intact tissue grown hydroponically, at the R2, R4, and R6 growth stages. As phosphorus in the nutrient solution decreased from 0.45 to 0.05 millimolar, the vacuolar phosphate peak became less prominent relative to cytoplasmic phosphate and hexose monophosphate peaks. At a nutrient phosphate concentration of 0.05 millimolar, the vacuolar phosphate peak was not detectable. At higher levels of nutrient phosphate, as plants progressed from the R2 to the R6 growth stage, the vacuolar phosphate peak was the first to disappear, suggesting that storage phosphate was remobilized to a greater extent than metabolic phosphate. Under suboptimal phosphate nutrition (≤ 0.20 millimolar), the hexose monophosphate and cytoplasmic phosphate peaks declined earlier in reproductive development than when phosphate was present in optimal amounts. Under low phosphate concentrations (0.05 millimolar) cytoplasmic phosphate was greatly reduced. Carbon metabolism was coincidently disrupted under low phosphate nutrition as shown by the appearance of large, prominent starch grains in the leaves. Cytoplasmic phosphate, and leaf carbon metabolism dependent on it, are buffered by vacuolar phosphate until late stages of reproductive growth. Images Figure 4 PMID:16666705

An experimental study of Fe-Ni exchange between sulfide melt and olivine at upper mantle conditions: implications for mantle sulfide compositions and phase equilibria

Science.gov (United States)

Zhang, Zhou; von der Handt, Anette; Hirschmann, Marc M.

2018-03-01

The behavior of nickel in the Earth's mantle is controlled by sulfide melt-olivine reaction. Prior to this study, experiments were carried out at low pressures with narrow range of Ni/Fe in sulfide melt. As the mantle becomes more reduced with depth, experiments at comparable conditions provide an assessment of the effect of pressure at low-oxygen fugacity conditions. In this study, we constrain the Fe-Ni composition of molten sulfide in the Earth's upper mantle via sulfide melt-olivine reaction experiments at 2 GPa, 1200 and 1400 °C, with sulfide melt X_{{{Ni}}}^{{{Sulfide}}}={{Ni}}/{{Ni+{Fe}}} (atomic ratio) ranging from 0 to 0.94. To verify the approach to equilibrium and to explore the effect of {f_{{{O}2}}} on Fe-Ni exchange between phases, four different suites of experiments were conducted, varying in their experimental geometry and initial composition. Effects of Ni secondary fluorescence on olivine analyses were corrected using the PENELOPE algorithm (Baró et al., Nucl Instrum Methods Phys Res B 100:31-46, 1995), "zero time" experiments, and measurements before and after dissolution of surrounding sulfides. Oxygen fugacities in the experiments, estimated from the measured O contents of sulfide melts and from the compositions of coexisting olivines, were 3.0 ± 1.0 log units more reduced than the fayalite-magnetite-quartz (FMQ) buffer (suite 1, 2 and 3), and FMQ - 1 or more oxidized (suite 4). For the reduced (suites 1-3) experiments, Fe-Ni distribution coefficients K_{{D}}{}={(X_{{{Ni}}}^{{{sulfide}}}/X_{{{Fe}}}^{{{sulfide}}})}/{(X_{{{Ni}}^{{{olivine}}}/X_{{{Fe}}}^{{{olivine}}})}} are small, averaging 10.0 ± 5.7, with little variation as a function of total Ni content. More oxidized experiments (suite 4) give larger values of K D (21.1-25.2). Compared to previous determinations at 100 kPa, values of K D from this study are chiefly lower, in large part owing to the more reduced conditions of the experiments. The observed difference does not seem

LiFePO4/C nanocomposites for lithium-ion batteries

Science.gov (United States)

Eftekhari, Ali

2017-03-01

LiFePO4, as the most famous member of the family of olivine-type lithium transition metal phosphates, is one of the promising candidates for the cathodes of lithium-ion batteries. However, its battery performance is limited by its low electrical conductivity and slow Li solid-state diffusion. Various methods have been attempted to improve the battery performance of lithium iron phosphate. Among them, compositing the LiFePO4 with carbon nanomaterials seems to be the most promising, as it is facile and efficient. Carbon nanomaterials usually serve as a conductive agent to improve the electrical conductivity while increasing the material porosity in which the solid-state diffusion distances are significantly shortened. Owing to the popularity of various carbonaceous nanomaterials, there is no straightforward line of research for comparing the LiFePO4/C nanocomposites. This review aims to provide a general perspective based on the research achievements reported in the literature. While surveying the research findings reported in the literature, controversial issues are also discussed. The possible contribution of pseudocapacitance as a result of functionalized carbon or LiFePO4 lattice defects is described, since from a practical perspective, a LiFePO4/C electrode can be considered as a supercapacitor at high C rates (with a specific capacitance as large as 200 F g-1). The Li diffusion in LiFePO4 has not been well understood yet; while the Li diffusion within the LiFePO4 lattice seems to be quite fast, the peculiar interfacial electrochemistry of LiFePO4 slows down the diffusion within the entire electrode by a few orders of magnitude.

Genetic relationship between deformation and low-Ca content in olivine from magmatic systems: evidence from the Poyi ultramafic intrusion, NW China

Science.gov (United States)

Yao, Zhuo-sen; Qin, Ke-zhang; Xue, Sheng-chao

2017-12-01

The deformation features (e.g., undulose extinction and subgrain boundaries) and low Ca content (causing the widespread deformation observed in Ca-depleted olivine from Poyi and other intrusions. What is more important, this work fills the gaps in the interpretation of this type of olivine in volcanic rocks.

Effects of education on low-phosphate diet and phosphate binder intake to control serum phosphate among maintenance hemodialysis patients: A randomized controlled trial

Directory of Open Access Journals (Sweden)

Eunsoo Lim

2018-03-01

Full Text Available Background : For phosphate control, patient education is essential due to the limited clearance of phosphate by dialysis. However, well-designed randomized controlled trials about dietary and phosphate binder education have been scarce. Methods : We enrolled maintenance hemodialysis patients and randomized them into an education group (n = 48 or a control group (n = 22. We assessed the patients' drug compliance and their knowledge about the phosphate binder using a questionnaire. Results : The primary goal was to increase the number of patients who reached a calcium-phosphorus product of lower than 55. In the education group, 36 (75.0% patients achieved the primary goal, as compared with 16 (72.7% in the control group (P = 0.430. The education increased the proportion of patients who properly took the phosphate binder (22.9% vs. 3.5%, P = 0.087, but not to statistical significance. Education did not affect the amount of dietary phosphate intake per body weight (education vs. control: -1.18 ± 3.54 vs. -0.88 ± 2.04 mg/kg, P = 0.851. However, the dietary phosphate-to-protein ratio tended to be lower in the education group (-0.64 ± 2.04 vs. 0.65 ± 3.55, P = 0.193. The education on phosphate restriction affected neither the Patient-Generated Subjective Global Assessment score (0.17 ± 4.58 vs. -0.86 ± 3.86, P = 0.363 nor the level of dietary protein intake (-0.03 ± 0.33 vs. -0.09 ± 0.18, P = 0.569. Conclusion : Education did not affect the calcium-phosphate product. Education on the proper timing of phosphate binder intake and the dietary phosphate-to-protein ratio showed marginal efficacy.

Deducing Water Concentrations in the Parent Magma of Cumulate Clinopyroxene and Olivine: Implications for a Hydrous Parent Melt of a Primitive Deccan Lava

Science.gov (United States)

Seaman, S. J.

2017-12-01

Water concentrations of clinopyroxene megacrysts in the Powai ankaramite flow, located near Mumbai, Deccan province, India, indicate that the parent magma of the flow hosted at least 4.3 wt.% water, an unusually high water concentration for a continental flood basalt magma. The Powai flow hosts clinopyroxene and olivine phenocrysts. Chatterjee and Sheth (2015) showed that phenocrysts in the flow were part of a cumulate layer intruded by basaltic melt at 6 kb and 1230oC, so the phenocrysts record characteristics of the cumulate parent melt. Clinopyroxene phenocrysts are oscillatorily zoned in water, Mg, Fe, and Ca concentrations, and have concentric bands 100-200 microns thick of 10-20 micron diameter melt inclusions. Olivine phenocrysts host only larger isolated melt inclusions. Zones in the cpx phenocrysts where melt inclusion-rich concentric bands occur have higher concentrations of water than inclusion-free zones. Water concentrations of cpx were used to calculate water concentrations in the melt from which the crystals formed using partition coefficients of Hauri et al. (2004). Water concentrations in the parent magma were between 4.3 and 8.2 wt. % based on water concentrations in cpx. Both Mg and Fe are relatively depleted in the water- and melt inclusion-rich zones in cpx, and Ca is enriched in these zones. Oscillatory zoning in cpx may be a result of repeated growth of cpx in water- richer and water-poorer boundary layers where water lowered melt viscosity and enhanced diffusion and crystal growth rates. Water-enhanced growth rates may have resulted in capture of melt inclusions preserved in water-rich cpx zones. Melt inclusions in olivine phenocrysts preserve lower water concentrations ( 1.2 wt. %) than those indicated by water concentration in cpx phenocrysts. This disparity may be evidence of water loss from melt inclusions in olivine (Gaetani et al., 2009) or may indicate that cpx and ol crystals did not crystallize from the same parent at the same time.

Magma transport and olivine crystallization depths in Kīlauea’s East Rift Zone inferred from experimentally rehomogenized melt inclusions

Science.gov (United States)

Tuohy, Robin M; Wallace, Paul J.; Loewen, Matthew W; Swanson, Don; Kent, Adam J R

2016-01-01

Concentrations of H2O and CO2 in olivine-hosted melt inclusions can be used to estimate crystallization depths for the olivine host. However, the original dissolved CO2concentration of melt inclusions at the time of trapping can be difficult to measure directly because in many cases substantial CO2 is transferred to shrinkage bubbles that form during post-entrapment cooling and crystallization. To investigate this problem, we heated olivine from the 1959 Kīlauea Iki and 1960 Kapoho (Hawai‘i) eruptions in a 1-atm furnace to temperatures above the melt inclusion trapping temperature to redissolve the CO2 in shrinkage bubbles. The measured CO2 concentrations of the experimentally rehomogenized inclusions (⩽590 ppm for Kīlauea Iki [n=10]; ⩽880 ppm for Kapoho, with one inclusion at 1863 ppm [n=38]) overlap with values for naturally quenched inclusions from the same samples, but experimentally rehomogenized inclusions have higher within-sample median CO2 values than naturally quenched inclusions, indicating at least partial dissolution of CO2 from the vapor bubble during heating. Comparison of our data with predictions from modeling of vapor bubble formation and published Raman data on the density of CO2 in the vapor bubbles suggests that 55-85% of the dissolved CO2 in the melt inclusions at the time of trapping was lost to post-entrapment shrinkage bubbles. Our results combined with the Raman data demonstrate that olivine from the early part of the Kīlauea Iki eruption crystallized at <6 km depth, with the majority of olivine in the 1-3 km depth range. These depths are consistent with the interpretation that the Kīlauea Iki magma was supplied from Kīlauea’s summit magma reservoir (∼2-5 km depth). In contrast, olivine from Kapoho, which was the rift zone extension of the Kīlauea Iki eruption, crystallized over a much wider range of depths (∼1-16 km). The wider depth range requires magma transport during the Kapoho eruption from deep beneath the

Partition of Ni between olivine and sulfide: the effect of temperature, f_{{text{O}}_{text{2}} } and f_{{text{S}}_{text{2}} }

Science.gov (United States)

Fleet, M. E.; Macrae, N. D.

1987-03-01

The experimental distribution coefficient for Ni/ Fe exchange between olivine and monosulfide (KD3) is 35.6±1.1 at 1385° C, f_{{text{O}}_{text{2}} } = 10^{ - 8.87} ,f_{{text{S}}_{text{2}} } = 10^{ - 1.02} , and olivine of composition Fo96 to Fo92. These are the physicochemical conditions appropriate to hypothesized sulfur-saturated komatiite magma. The present experiments equilibrated natural olivine grains with sulfide-oxide liquid in the presence of a (Mg, Fe)-alumino-silicate melt. By a variety of different experimental procedures, K D3 is shown to be essentially constant at about 30 to 35 in the temperature range 900 to 1400° C, for olivine of composition Fo97 to FoO, monosulfide composition with up to 70 mol. % NiS, and a wide range of f_{{text{O}}_{text{2}} } and f_{{text{S}}_{text{2}} }.

Hydrogen permeation resistant phosphate coatings

International Nuclear Information System (INIS)

McGuire, J.C.

1979-01-01

A method for reducing hydrogen diffusion through metal wherein the metal is coated with a phosphate-radical-containing, phosphate-glass-forming material on at least one surface thereof. The coating is then heated to at least 350 0 C to form a phosphate glass. This method is especially applicable to nuclear reactors to minimize tritium diffusion. The coating is preferably formed with a solution of phosphoric acid which may also contain compounds such as MnSO 4 , SiO 2 and Na 2 Cr 2 0 7 . (author)

Hydrogen permeation resistant phosphate coatings

International Nuclear Information System (INIS)

McGuire, J.C.

1979-01-01

A method for reducing hydrogen diffusion through metal is described. The metal is coated with a phosphate-radical-containing, phosphate-glass-forming material on at least one surface. The coating is then heated to at least 350 0 C to form a phosphate glass. This method is especially applicable to nuclear reactors to minimize tritium diffusion. The coating is preferably formed with a solution of phosphoric acid which may also contain compounds such as MnSO 4 , SiO 2 and Na 2 Cr 2 O 7 . (author)

Electrical conductivity and reaction with lithium of LiFe{sub 1-y}Mn{sub y}PO{sub 4} olivine-type cathode materials

Energy Technology Data Exchange (ETDEWEB)

Molenda, J.; Ojczyk, W.; Marzec, J. [Faculty of Materials Science and Ceramics, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow (Poland)

2007-12-06

Structural, electrical and electrochemical properties of Mn-substituted phospho-olivines LiFe{sub 1-y}Mn{sub y}PO{sub 4} were investigated and compared to those of LiFePO{sub 4}. Rietvield refined XRD patterns taken in the course of delithiation process showed apparent difference between phase compositions of these cathode materials upon lithium extraction. Contrary to the LiFePO{sub 4} and LiMnPO{sub 4} compositions for which a two-phase mechanism of electrochemical lithium extraction/insertion is observed, in case of Mn-substituted LiFe{sub 1-y}Mn{sub y}PO{sub 4} samples a single-phase mechanism of deintercalation was observed in the studied range of lithium concentration. Electrochemical characterization of the cathode materials were performed in Li/Li{sup +}/Li{sub x}Fe{sub 1-y}Mn{sub y}PO{sub 4}-type cells for y = 0.0, 0.25, 0.55, 0.75 and 1.0 compositions. Voltammery studies showed low reversibility of the lithium extraction process in the high-voltage ''manganese'' range, while in the ''iron'' range the reversibility of lithium extraction is high. Impedance measurements of the LiFe{sub 1-y}Mn{sub y}PO{sub 4} cathode materials, which enabled separation of the ionic and electronic components of their entire electrical conductivity, showed distinct influence of Mn content on the electronic part of conductivity. EIS measurements performed at different states of cell charge revealed that the charge-transfer impedance in Li{sub x}Fe{sub 1-y}Mn{sub y}PO{sub 4} is much lower than that of Li{sub x}FePO{sub 4}. (author)

Luminescence and excited state dynamics in Bi3+-doped LiLaP4O12 phosphates

International Nuclear Information System (INIS)

Babin, V.; Chernenko, K.; Demchenko, P.; Mihokova, E.; Nikl, M.; Pashuk, I.; Shalapska, T.; Voloshinovskii, A.; Zazubovich, S.

2016-01-01

Photo- and X-ray-excited luminescence characteristics of Bi-doped LiLaP 4 O 12 phosphates with different bismuth contents (from 1 to 25 at% in the melt) are investigated in the 4.2–300 K temperature range and compared with the characteristics of the undoped LiLaP 4 O 12 phosphate. The broad 2.95 eV emission band of LiLaP 4 O 12 :Bi excited around 5.4 eV is found to arise from the bismuth dopant. Relatively large FWHM and Stokes shift of the emission band and especially the data on the low-temperature decay kinetics of the 2.95 eV emission and its temperature dependence, indicating a very small spin-orbit splitting energy of the corresponding excited state, allow the conclusion that this emission arises from the radiative decay of the triplet state of an exciton localized around a Bi 3+ ion. No spectral bands are observed, arising from the electron transitions between the energy levels of Bi 3+ ions. Phenomenological model is proposed for the description of the excited state dynamics of the Bi 3+ -related localized exciton in LiLaP 4 O 12 :Bi and the parameters of the triplet localized exciton state are determined. Keywords: Photoluminescence; Time-resolved spectroscopy; Excited states; Bi 3+ centers; LiLaP 4 O 12 :Bi powders

LiFePO4 Nanostructures Fabricated from Iron(III) Phosphate (FePO4 x 2H2O) by Hydrothermal Method.

Science.gov (United States)

Saji, Viswanathan S; Song, Hyun-Kon

2015-01-01

Electrode materials having nanometer scale dimensions are expected to have property enhancements due to enhanced surface area and mass/charge transport kinetics. This is particularly relevant to intrinsically low electronically conductive materials such as lithium iron phosphate (LiFePO4), which is of recent research interest as a high performance intercalation electrode material for Li-ion batteries. Many of the reported works on LiFePO4 synthesis are unattractive either due to the high cost of raw materials or due to the complex synthesis technique. In this direction, synthesis of LiFePO4 directly from inexpensive FePO4 shows promise.The present study reports LiFePO4 nanostructures prepared from iron (III) phosphate (FePO4 x 2H2O) by precipitation-hydrothermal method. The sintered powder was characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Inductive coupled plasma-optical emission spectroscopy (ICP-OES), and Electron microscopy (SEM and TEM). Two synthesis methods, viz. bulk synthesis and anodized aluminum oxide (AAO) template-assisted synthesis are reported. By bulk synthesis, micro-sized particles having peculiar surface nanostructuring were formed at precipitation pH of 6.0 to 7.5 whereas typical nanosized LiFePO4 resulted at pH ≥ 8.0. An in-situ precipitation strategy inside the pores of AAO utilizing the spin coating was utilized for the AAO-template-assisted synthesis. The template with pores filled with the precipitate was subsequently subjected to hydrothermal process and high temperature sintering to fabricate compact rod-like structures.

Electrochemical Reduction of Zinc Phosphate

International Nuclear Information System (INIS)

Kim, Chang Hwan; Lee, Jung Hyun; Shin, Woon Sup

2010-01-01

We demonstrated first that the electrochemical reduction of zinc phosphate in neutral phosphate buffer is possible and potentially applicable to bio-compatible rechargeable battery. The actual redox component is Zn(s)/Zn phosphate(s) and the future research about the control of crystal formation for the better cyclability is required. In lead-acid battery, the electrochemical redox reaction of Pb (s) /PbSO 4(s) is used by reducing Pb(II) and oxidizing Pb(0) in sulfate rich solution. Since both reduced form and oxidized form are insoluble, they cannot diffuse to the opposite electrodes and react. It is a very common strategy to make a stable battery electrode that a metal element is reduced and oxidized in solution containing an abundance of anion readily precipitating with the metal ion. For the application of this strategy to construction of rechargeable battery using bio-compatible electrode materials and electrolytes, the use of phosphate ion can be considered as anion readily precipitating with metal ions. If phosphate buffer with neutral pH is used as electrolyte, the better bio-compatibility will be achieved than most of rechargeable battery using strong acid, strong base or organic solvent as electrolyte solution. There are many metal ions readily precipitating with phos-phate ion, and zinc is one of them

Metal complex derivatives of hydrogen uranyl phosphate

International Nuclear Information System (INIS)

Grohol, D.; Blinn, E.L.

1994-01-01

Derivatives of hydrogen uranyl phosphate were prepared by incorporating transition metal complexes into the uranyl phosphate matrix. The transition metal complexes employed include bis(ethylenediamine)copper(II), bis(1,3-propanediamine)copper(II) chloride, (triethylenetetramine)copper(II), (1,4,8,11-tetraazacyclotetradecane)copper(II), (1,4,8,12-tetraazacyclopentadecane)copper(II), (1,4,8,11-tetraazacyclotetradecane)nickel(II) chloride, (triethylenetetramine)nickel(II) and others. The chemical analyses of these derivatives indicated that the incorporation of the transition metal complexes into the uranyl phosphate matrix via ion exchange was not stoichiometric. The extent of ion exchange is dependent on the size and structure of the transition metal complex. All complexes were characterized by X-ray powder diffractometry, electronic and infrared spectra, thermal analyses and chemical analysis. An attempt was made to correlate the degree of quenching of the luminescence of the uranyl ion to the spacing between the uranyl phosphate layers in the derivatives

Mn-Cr dating of Fe- and Ca-rich olivine from 'quenched' and 'plutonic' angrite meteorites using Secondary Ion Mass Spectrometry

Science.gov (United States)

McKibbin, Seann J.; Ireland, Trevor R.; Amelin, Yuri; Holden, Peter

2015-05-01

angrites Northwest Africa (NWA) 4590 and 4801 we have found initial 53Mn/55Mn values which are consistent with more precise work, at 0.90 (±0.4) × 10-6 and 0.13 (±1.1) × 10-6 respectively. Our work shows that SIMS can usefully constrain and distinguish the ages of angrites of different petrologic groups. In reviewing the petrology of angrites, we suggest that NWA 2999, 4590, and 4801 underwent a secondary partial melting and Cr (+/-Pb) disturbance event that the sub-volcanic Lewis Cliff 86010, and perhaps the plutonic Angra dos Reis, did not. With our higher initial 53Mn/55Mn for D'Orbigny and Sahara 99555 as well as previous data, a combined quenched angrite initial 53Mn/55Mn of 3.47 (±0.12) × 10-6 (2-sigma, MSWD 1.00) yields consistent Mn-Cr and U-Pb intervals between these angrites and Lewis Cliff 86010. Discrepant Mn-Cr timescales for other plutonic and sub-volcanic angrites represents resetting during the secondary partial melting event at ∼4557.2 Ma and indicates a relative order of disturbance of isotope systems: Mn-Cr in olivine before U-Pb in pyroxene, with Hf-W in pyroxene being the most resistant.

Americium and plutonium in phosphates of trigonal structure (NZP type) Am1/3[Zr2(PO4)3] and Pu1/4[Zr2(PO4)3

International Nuclear Information System (INIS)

Bykov, D.M.; Orlova, A.I.; Tomilin, S.V.; Lizin, A.A.; Lukinykh, A.N.

2006-01-01

Am 1/3 [Zr 2 (PO 4 ) 3 ] and Pu 1/4 [Zr 2 (PO 4 ) 3 ] phosphates are synthesized and are investigated by X-ray diffraction method. Compounds have triclinic lattices and lattice parameters are determined. Possibility of actinide inclusion into hollows of framework of NZP type is shown for the first time. It is proposed that inclusion of Pu and Am highly-charged cations into framework hollows decreases crystal structure symmetry up to primitive trigonal one. Rate of Pu leaching from ceramics on Pu 1/4 [Zr 2 (PO 4 ) 3 ] basis are measured [ru

Radiological impact of natural radioactivity in Egyptian phosphate rocks, phosphogypsum and phosphate fertilizers

International Nuclear Information System (INIS)

El-Bahi, S.M.; Sroor, A.; Mohamed, Gehan Y.; El-Gendy, N.S.

2017-01-01

In this study, the activity concentrations of the natural radionuclides in phosphate rocks and its products were measured using a high- purity germanium detector (HPGe). The obtained activity results show remarkable wide variation in the radioactive contents for the different phosphate samples. The average activity concentration of "2"3"5U, "2"3"8U, "2"2"6Ra, "2"3"2Th and "4"0K was found as (45, 1031, 786, 85 and 765 Bq/kg) for phosphate rocks, (28, 1234, 457, 123 and 819 Bq/kg) for phosphate fertilizers, (47, 663, 550, 79 and 870 Bq/kg) for phosphogypsum and (25, 543, 409, 54 and 897 Bq/kg) for single super phosphate respectively. Based on the measured activities, the radiological parameters (activity concentration index, absorbed gamma dose rate in outdoor and indoor and the corresponding annual effective dose rates and total excess lifetime cancer risk) were estimated to assess the radiological hazards. The total excess lifetime cancer risk (ELCR) has been calculated and found to be high in all samples, which related to high radioactivity, representing radiological risk for the health of the population. - Highlights: • Level of radioactivity of phosphate rocks and by-products samples. • The radiological health hazard parameters. • Radiological risk to the health of the population. • The excess lifetime cancer risk factor.

Dislocation Interactions in Olivine Revealed by HR-EBSD

Science.gov (United States)

Wallis, David; Hansen, Lars N.; Britton, T. Ben; Wilkinson, Angus J.

2017-10-01

Interactions between dislocations potentially provide a control on strain rates produced by dislocation motion during creep of rocks at high temperatures. However, it has been difficult to establish the dominant types of interactions and their influence on the rheological properties of creeping rocks due to a lack of suitable observational techniques. We apply high-angular resolution electron backscatter diffraction to map geometrically necessary dislocation (GND) density, elastic strain, and residual stress in experimentally deformed single crystals of olivine. Short-range interactions are revealed by cross correlation of GND density maps. Spatial correlations between dislocation types indicate that noncollinear interactions may impede motion of proximal dislocations at temperatures of 1000°C and 1200°C. Long-range interactions are revealed by autocorrelation of GND density maps. These analyses reveal periodic variations in GND density and sign, with characteristic length scales on the order of 1-10 μm. These structures are spatially associated with variations in elastic strain and residual stress on the order of 10-3 and 100 MPa, respectively. Therefore, short-range interactions generate local accumulations of dislocations, leading to heterogeneous internal stress fields that influence dislocation motion over longer length scales. The impacts of these short- and/or long-range interactions on dislocation velocities may therefore influence the strain rate of the bulk material and are an important consideration for future models of dislocation-mediated deformation mechanisms in olivine. Establishing the types and impacts of dislocation interactions that occur across a range of laboratory and natural deformation conditions will help to establish the reliability of extrapolating laboratory-derived flow laws to real Earth conditions.

Microseismic Monitoring of the Olivine → Spinel Transition in Fayalite Under Non-Hydrostatic Stress

Science.gov (United States)

Officer, T.; Secco, R. A.

2016-12-01

In subduction zones, deep earthquakes are thought to be associated with faulting that arises from phase transformations. In order to test the viability of this mechanism experimentally, it is necessary to make microseismic measurements while the mineral under investigation is subjected to the pressure and temperature (P,T) environment at depth. A system has been developed capable of making in situ acoustic emission (AE) measurements on samples under P,T conditions representative of the upper mantle and transition zone. Experiments are performed in a 3000-ton multi-anvil press using an 18/11 octahedral cell with 6 piezoelectric transducers mounted on the rear side of the anvils. AE signals are collected at a sampling rate of 40 MHz using a triggered system and a data buffer for continuous recording so full waveforms of AE events are captured. The use of multiple transducers distributed in a microseismic array allows for events to be located within the sample through automatic arrival time picking and least squares inversion techniques. The multi-anvil apparatus constitutes an inherently noisy environment both acoustically and electrically, therefore methods of noise reduction were developed and will be discussed. This technique has been used to measure acoustic signals generated from the fracturing of quartz beads during high pressure deformation and to investigate the possibility that the phase transformation from olivine to spinel, known to occur in subduction zones, is associated with deep-focus earthquakes (300 - 690 km depth). The analog material fayalite (Fe2SiO4), the iron end member of olivine, has been examined. Information about its synthesis and sintering will be discussed as well as results of AE experiments on samples experiencing deviatoric stress under high pressure (P = 4-9 GPa) and high temperature (T = 773-1273 K) conditions in the spinel stability field.

Two Dimensional X-Ray Diffraction (2D-XRD) studies on Olivine of U.S.A

International Nuclear Information System (INIS)

Jabeen, S.; Raza, S.M.; Ahmed, M.A.; Zai, M.Y.; Elacher, K.

2011-01-01

The Olivine (Mg, Fe) 2SiO/sub 4/ of USA has been studied with two dimensional X-ray diffractometer (D8 discover with GADDS). The two distinct phases of orthorhombic structure, one with Mg/sub 8/[Fe/sub 2/SiO/sub 4/] and the other with Mg/sub 2/SiO/sub 4/ is observed. We also observed phase transitions due to presence of iron and Silicon preferably the structural change of Mg/sub 8/[Fe/sub 2/SiO/sub 4/] from orthorhombic to spinel like (spinel chord) structure. Magnesium ions in Mg/sub 8/[Fe/sub 2/SiO/sub 4/] shuffle, arrange at the five vertices of a pentagon and the remaining three at the central but with displaced position from the plane of the pentagon, Thus resulting into a three dimensional spinel chord like structure. We evidenced the same from diverse orientations of phase peaks and indeed from Kossel lines. (author)

Na-doped LiMnPO4 as an electrode material for enhanced lithium ...

Indian Academy of Sciences (India)

and electrochemical performance. Lithium manganese ... bond enables good thermal and cycling stability [4,5]. The ... Moreover, the surface morphologies are an essential factor ... work, electrochemically inactive cations were replaced par-.

Layered ordering of vacancies of lead iron phosphate Pb{sub 3}Fe{sub 2}(PO{sub 4}){sub 4}

Energy Technology Data Exchange (ETDEWEB)

Malakho, A.P. [Moscow State Univ., Dept. of Material Science (Russian Federation); Morozov, V.A.; Pokholok, V.; Lazoryak, B.I. [Moscow State Univ., Dept. of Chemisty (Russian Federation); Morozov, V.A.; Van Tendeloo, G. [Antwerp Univ., EMAT (Belgium)

2005-07-01

Lead iron phosphate Pb{sub 3}Fe{sub 2}(PO{sub 4}){sub 4} has been synthesized by solid state method and characterized by X-ray powder and electron diffraction, differential scanning calorimetry, Moessbauer and infrared spectroscopy. A structural model for Pb{sub 3}Fe{sub 2}(PO{sub 4}){sub 4} is proposed and is refined by the Rietveld method. The compound crystallizes in the monoclinic space group P2{sub 1}/c with a=9.0065(6) Angstroms, b=9.0574(6) Angstroms, c=9.3057(6) Angstroms, {beta}=116.880(4) degrees, V=677.10(8) (Angstroms){sup 3}, Z=2, R{sub wp}=3.52%, R{sub p}=2.66%. It exhibits a structure with a three-dimensional open framework. The 3D framework is formed by PO{sub 4} tetrahedra and FeO{sub 6} octahedra connected via common vertices. 3/4 of cavities in the framework are occupied by lead and 1/4 are vacant. (authors)

Decontamination of liquid radioactive waste by thorium phosphate

International Nuclear Information System (INIS)

Rousselle, J.; Grandjean, S.; Dacheux, N.; Genet, M.

2004-01-01

In the field of the complete reexamination of the chemistry of thorium phosphate and of the improvement of the homogeneity of Thorium Phosphate Diphosphate (TPD, Th 4 (PO 4 ) 4 P 2 O 7 ) prepared at high temperature, several crystallized compounds were prepared as initial powdered precursors. Due to the very low solubility products associated to these phases, their use in the field of the efficient decontamination of high-level radioactive liquid waste containing actinides (An) was carefully considered. Two main processes (called 'oxalate' and 'hydrothermal' chemical routes) were developed through a new concept combining the decontamination of liquid waste and the immobilization of the actinides in a ceramic matrix (TPD). In phosphoric media ('hydrothermal route'), the key-precursor was the Thorium Phosphate Hydrogen Phosphate hydrate (Th 2 (PO 4 ) 2 (HPO 4 ). H 2 O, TPHP, solubility product log(K S,0 0 ) ∼ - 67). The replacement of thorium by other tetravalent actinides (U, Np, Pu) in the structure, leading to the preparation of Th 2-x/2 An x/2 (PO 4 ) 2 (HPO 4 ). H 2 O solid solutions, was examined. A second method was also considered in parallel to illustrate this concept using the more well-known precipitation of oxalate as the initial decontamination step. For this method, the final transformation to single phase TPD containing actinides was purchased by heating a mixture of phosphate ions with the oxalate precipitate at high temperature. (authors)

Ultralong Lifespan and Ultrafast Li Storage: Single-Crystal LiFePO4 Nanomeshes.

Science.gov (United States)

Zhang, Yan; Zhang, Hui Juan; Feng, Yang Yang; Fang, Ling; Wang, Yu

2016-01-27

A novel LiFePO4 material, in the shape of a nanomesh, has been rationally designed and synthesized based on the low crystal-mismatch strategy. The LiFePO4 nanomesh possesses several advantages in morphology and crystal structure, including a mesoporous structure, its crystal orientation that is along the [010] direction, and a shortened Li-ion diffusion path. These properties are favorable for their application as cathode in Li-ion batteries, as these will accelerate the Li-ion diffusion rate, improve the Li-ion exchange between the LiFePO4 nanomesh and the electrolyte, and reduce the Li-ion capacitive behavior during Li intercalation. So the LiFePO4 nanomesh exhibits a high specific capacity, enhanced rate capability, and strengthened cyclability. The method developed here can also be extended to other similar systems, for instance, LiMnPO4 , LiCoPO4 , and LiNiPO4 , and may find more applications in the designed synthesis of functional materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Iron phosphate materials as cathodes for lithium batteries

CERN Document Server

Prosini, Pier Paolo

2011-01-01

""Iron Phosphate Materials as Cathodes for Lithium Batteries"" describes the synthesis and the chemical-physical characteristics of iron phosphates, and presents methods of making LiFePO4 a suitable cathode material for lithium-ion batteries. The author studies carbon's ability to increase conductivity and to decrease material grain size, as well as investigating the electrochemical behaviour of the materials obtained. ""Iron Phosphate Materials as Cathodes for Lithium Batteries"" also proposes a model to explain lithium insertion/extraction in LiFePO4 and to predict voltage profiles at variou

3D WO3 /BiVO4 /Cobalt Phosphate Composites Inverse Opal Photoanode for Efficient Photoelectrochemical Water Splitting.

Science.gov (United States)

Zhang, Haifeng; Zhou, Weiwei; Yang, Yaping; Cheng, Chuanwei

2017-04-01

A novel 3D WO 3 /BiVO 4 /cobalt phosphate composite inverse opal is designed for photoeletrochemical (PEC) water splitting, yielding a significantly improved PEC performance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A study of phosphate absorption by magnesium iron hydroxycarbonate.

Science.gov (United States)

Du, Yi; Rees, Nicholas; O'Hare, Dermot

2009-10-21

A study of the mechanism of phosphate adsorption by magnesium iron hydroxycarbonate, [Mg(2.25)Fe(0.75)(OH)(6)](CO(3))(0.37).0.65H(2)O over a range of pH has been carried out. The efficiency of the phosphate removal from aqueous solution has been investigated between pH 3-9 and the resulting solid phases have been studied by elemental analysis, XRD, FT-IR, Raman, HRTEM, EDX and solid-state MAS (31)P NMR. The analytical and spectroscopic data suggest that phosphate removal from solution occurs not by anion intercalation of the relevant phosphorous oxyanion (H(2)PO(4)(-) or HPO(4)(2-)) into the LDH but by the precipitation of either an insoluble iron hydrogen phosphate hydrate and/or a magnesium phosphate hydrate.

The effect of different phosphate ion concentrations and ph of the phosphate buffer on lipase bioproduction by rhizopus oligosporus

International Nuclear Information System (INIS)

Haq, I.; Ali, S.; Awan, U.F.; Javed, W.; Mirza, S.

2005-01-01

In the present investigation, we report the effect of phosphate ion concentration and different ph of the phosphate buffer (as diluent) on lipase bioproduction by Rhizopus oligosporus. For this purpose, solid state fermentation was employed. Different agricultural by-products such as wheat bran, rice husk, almond meal, soybean meal and sunflower meal were used as substrate. The maximum lipase activity (72.60 U/g) was observed with the almond meal. Addition of phosphate ions (K/sub 2/HPO/sub 4/) influenced the lipase production. The ph of the phosphate buffer (7.0) was found to be effective for higher yield of lipase. (author)

Water, lithium and trace element compositions of olivine from Lanzo South replacive mantle dunites (Western Alps): New constraints into melt migration processes at cold thermal regimes

Science.gov (United States)

Sanfilippo, Alessio; Tribuzio, Riccardo; Ottolini, Luisa; Hamada, Morihisa

2017-10-01

Replacive mantle dunites are considered to be shallow pathways for extraction of mantle melts from their source region. Dunites offer a unique possibility to unravel the compositional variability of the melts produced in the upper mantle, before mixing and crystal fractionation modify their original signature. This study includes a quantification of H2O, Li and trace elements (Ni, Mn, Co, Sc, V, Ti, Zr, Y and HREE) in olivine from large replacive dunite bodies (>20 m) within a mantle section exposed in the Western Italian Alps (Lanzo South ophiolite). On the basis of olivine, clinopyroxene and spinel compositions, these dunites were previously interpreted to be formed by melts with a MORB signature. Variations in Ni, Mn, Co and Ca contents in olivine from different dunite bodies suggested formation by different melt batches. The variable H2O and Li contents of these olivines agree with this idea. Compared to olivine from residual peridotites and olivine phenocrysts in MORB (both having H2O 1 ppm), the Lanzo South dunite olivine has high H2O (18-40 ppm) and low Li (0.35-0.83 ppm) contents. Geochemical modelling suggests that the dunite-forming melts were produced by low melting degrees of a mixed garnet-pyroxenite-peridotite mantle source, with a contribution of a garnet pyroxenite component variable from 20 to 80%. The Lanzo dunites experienced migration of melts geochemically enriched and mainly produced in the lowermost part of the melting region. Extraction of enriched melts through dunite channels are probably characteristic of cold thermal regimes, where low temperatures and a thick mantle lithosphere inhibit mixing with melts produced at shallower depths.

Isolation and identification of a phosphate solubilising fungus from soil of a phosphate mine in Chaluse, Iran

Directory of Open Access Journals (Sweden)

Raheleh Jamshidi

2016-07-01

Full Text Available Microbial solubilisation of phosphorus from insoluble phosphates is an environmental friendly and cost effective approach in sustainable soil management. Introducing the indigenous microorganisms to soil requires shorter adaptation period and causes fewer ecological distortions than exogenous microorganisms. This study was conducted to isolate and identify the indigenous fungi for phosphate solubilisation in Mazandaran, Iran. A potent phosphate solubilising fungus was isolated from an Iranian phosphate mine and selected for solubilisation of rock phosphate (RP. The identified fungus was characterised by calmodulin-based polymerase chain reaction method as Aspergillus tubingensis SANRU (Sari Agricultural Sciences and Natural Resources University. The phosphate solubilisation ability of the fungal strain was carried out in shake-flask leaching experiments containing various concentrations of RP (1%, 2%, 4%, or 8% w/v. The maximum P solubilisation rate of 347 mg/l was achieved at 1% of RP concentration on day 9. The regression analysis indicated that the P solubilised mainly through acidification. This study shows the possibility of using A. tubingensis SANRU for application in the management of P fertilisation.

Characterization of iron phosphate glasses prepared by microwave heating

International Nuclear Information System (INIS)

Almeida, Fabio Jesus Moreira de

2006-01-01

Phosphate glasses have been investigated since the fifties, because they are relatively easy to prepare, have low melting temperatures (1000 deg C - 1200 deg C and low glass transition. However, these glasses were very sensitive to humidity, showing a very low chemical durability. Iron phosphate glasses have been prepared by melting inorganic precursors in conventional electric furnaces and induction furnaces. By adding iron, phosphate glasses became chemical resistant and were thought to be used as nuclear waste forms or mechanical resistance fibers. The use of microwaves has been investigated because it makes possible a fast and homogeneous heating of the materials. Microwave promotes the self-heating of the material by the interaction of the external electromagnetic field with the molecules and ions of the material. Niobium phosphate glasses was also produced already through the heating of precursors in microwave ovens. Other glasses containing iron in theirs structure was produced by conventional furnaces and they had your structures analyzed. But even so, it was not still published synthesis of iron phosphate glasses starting from the melting of precursors materials in microwave ovens. In the present work mixtures of (NH 4 ) 2 HPO 4 and Fe 3 O 4 or (NH 4 ) 2 HPO 4 and Fe 2 O 3 were exposed to microwave energy with electromagnetic waves of 2,45 GHz. It was proposed that the absorption of this radiation for the material causes the heating from room temperature to melting temperature. The obtained iron phosphate glasses was analyzed by X-ray diffraction, Moessbauer spectroscopy, and Differential Thermal Analysis. Iron phosphate glasses were also produced in electrical furnaces for comparison. (author)

Characterization of iron phosphate glasses prepared by microwave heating

International Nuclear Information System (INIS)

Almeida, Fabio Jesus Moreira de

2006-01-01

Phosphate glasses have been investigated since the fifties, because they are relatively easy to prepare, have low melting temperatures (1000 deg C - 1200 deg C), and low glass transition. However, these glasses were very sensitive to humidity, showing a very low chemical durability. Iron phosphate glasses have been prepared by melting inorganic precursors in conventional electric furnaces and induction furnaces. By adding iron, phosphate glasses became chemical resistant and were thought to be used as nuclear waste forms or mechanical resistance fibers. The use of microwaves has been investigated because it makes possible a fast and homogeneous heating of the materials. Microwave promotes the self-heating of the material by the interaction of the external electromagnetic field with the molecules and ions of the material. Niobium phosphate glasses was also produced already through the heating of precursors in microwave ovens. Other glasses containing iron in theirs structure was produced by conventional furnaces and they had your structures analyzed. But even so, it was not still published synthesis of iron phosphate glasses starting from the melting of precursors materials in microwave ovens. In the present work mixtures of (NH 4 ) 2 HPO 4 and Fe 3 O 4 or (NH 4 ) 2 HPO 4 and Fe 2 O 3 were exposed to microwave energy with electromagnetic waves of 2,45 GHz. It was proposed that the absorption of this radiation for the material causes the heating from room temperature to melting temperature. The obtained iron phosphate glasses was analyzed by X-ray diffraction, Moessbauer spectroscopy, and Differential Thermal Analysis. Iron phosphate glasses were also produced in electrical furnaces for comparison. (author)

Synthesis and characterization of porous calcium phosphate

International Nuclear Information System (INIS)

Granados C, F.; Serrano G, J.; Bonifacio M, J.

2007-01-01

The porous calcium phosphate was prepared by the continuous precipitation method using Ca(NO 3 ) 2 .4H 2 O and NH 4 H 2 PO 4 salts. The synthesized material was structurally and superficially characterized using the XRD, BET, IR TGA and SEM techniques. The obtained inorganic material was identified as calcium phosphate that presents a great specific area for what can be efficiently used as adsorbent material for adsorption studies in the radioactive wastes treatment present in aqueous solution. (Author)

Structural and Electrochemical Characterization of Pure LiFePO4 and Nanocomposite C-LiFePO4 Cathodes for Lithium Ion Rechargeable Batteries

Directory of Open Access Journals (Sweden)

Arun Kumar

2009-01-01

Full Text Available Pure lithium iron phosphate (LiFePO4 and carbon-coated LiFePO4 (C-LiFePO4 cathode materials were synthesized for Li-ion batteries. Structural and electrochemical properties of these materials were compared. X-ray diffraction revealed orthorhombic olivine structure. Micro-Raman scattering analysis indicates amorphous carbon, and TEM micrographs show carbon coating on LiFePO4 particles. Ex situ Raman spectrum of C-LiFePO4 at various stages of charging and discharging showed reversibility upon electrochemical cycling. The cyclic voltammograms of LiFePO4 and C-LiFePO4 showed only a pair of peaks corresponding to the anodic and cathodic reactions. The first discharge capacities were 63, 43, and 13 mAh/g for C/5, C/3, and C/2, respectively for LiFePO4 where as in case of C-LiFePO4 that were 163, 144, 118, and 70 mAh/g for C/5, C/3, C/2, and 1C, respectively. The capacity retention of pure LiFePO4 was 69% after 25 cycles where as that of C-LiFePO4 was around 97% after 50 cycles. These results indicate that the capacity and the rate capability improved significantly upon carbon coating.

Structure and spectroscopy of rare earth – Doped lead phosphate glasses

International Nuclear Information System (INIS)

Pisarski, Wojciech A.; Żur, Lidia; Goryczka, Tomasz; Sołtys, Marta; Pisarska, Joanna

2014-01-01

Highlights: • Lead phosphate glasses doped with rare earth ions were prepared. • The local structure was examined using X-ray diffraction and spectroscopic methods. • Different structural phosphate groups are present in lead phosphate glasses. • The electron–phonon coupling strength and phonon energy of the glass host was determined. • Several observed emission bands are due to 4f–4f electronic transitions of rare earth ions. -- Abstract: Lead–gallium phosphate glasses doped with rare the earth ions (Eu 3+ , Dy 3+ , Tb 3+ , Er 3+ ) were synthesized. The structure of obtained glasses was examined by means of use: X-ray diffraction (XRD), nuclear magnetic resonance ( 207 Pb and 31 P NMR), fourier transform infrared (FT-IR) and Raman spectroscopy. In contrast to fully amorphous Ln-doped samples (Ln = Eu, Dy, Tb), in Er-doped sample the GaPO 4 crystalline phase was identified. It was found from the NMR, FT-IR and Raman spectroscopic techniques that, different structural phosphate groups were present in lead phosphate glasses. Based on absorption measurements, the UV–VIS cut-off wavelength for lead phosphate glass was determined and its value is close to 305 nm. Excitation and emission spectra of rare earths were also detected. From excitation spectra of Eu 3+ the electron–phonon coupling strength and phonon energy of the glass host were determined. Due to 4f 6 –4f 6 (Eu 3+ ), 4f 8 –4f 8 (Tb 3+ ), 4f 9 –4f 9 (Dy 3+ ) and 4f 11 –4f 11 (Er 3+ ) electronic transitions of trivalent rare earth ions several luminescence bands were stated

Hydrothermal synthesis, structural and physico-chemical characterizations of two Nasicon phosphates: M0.50IITi2(PO4)3 (M = Mn, Co)

International Nuclear Information System (INIS)

Essehli, Rachid; Bali, Brahim El; Benmokhtar, S.; Fejfarova, Karla; Dusek, Michal

2009-01-01

The family of titanium Nasicon-phosphates of generic formula M 0.5 II Ti 2 (PO 4 ) 3 has been revisited using hydrothermal techniques. Two phases have been synthesized: Mn 0.5 II Ti 2 (PO 4 ) 3 (MnTiP) and Co 0.5 II Ti 2 (PO 4 ) 3 (CoTiP). Single crystal diffraction studies show that they exhibit two different structural types. Mn 0.5 II Ti 2 (PO 4 ) 3 phosphate crystallizes in the R-3 space group, with the cell parameters a = 8.51300(10) A and c = 21.0083(3) A (V = 1318.52(3) A 3 and Z = 6). The Co 0.5 II Ti 2 (PO 4 ) 3 phosphate crystallizes in the R-3c space group, with a = 8.4608(9) A and c = 21.174(2) A (V = 1312.7(2) A 3 and Z = 6). These two compounds are clearly related to the parent Nasicon-type rhombohedral structure, which can be described using [Ti 2 (PO 4 ) 3 ] framework composed of two [TiO 6 ] octahedral interlinked via three [PO 4 ] tetrahedra. 31 P magic-angle spinning nuclear magnetic resonance (MAS-NMR) data are presented as supporting data. Curie-Weiss-type behavior is observed in the magnetic susceptibility. The phases are also characterized by IR spectroscopy and UV-visible.

Intercalation compounds of vanadium(5) phosphates with glycerol

International Nuclear Information System (INIS)

Yakovleva, T.N.; Vykhodtseva, K.I.; Tarasova, D.V.; Soderzhinova, M.M.

1997-01-01

Interaction products of glycerol aqueous solutions with vanadium(5) phosphates were investigated by the methods of ESR, X-ray phase and thermal analyses. It is shown that glycerol molecules enter the interlayer space of VOPO 4 · 2H 2 O lattice with formation of disordered intercalated compounds with glycerol on the basis of partially reduced vanadium phosphate form when using α-VOPO 4 . 16 refs., 4 figs., 1 tab

Electrochemical performances of LiNi1−xMnxPO4 (x = 0.05–0.2) olivine cathode materials for high voltage rechargeable lithium ion batteries

DEFF Research Database (Denmark)

Karthikprabhu, S.; Karuppasamy, K.; Vikraman, Dhanasekaran

2018-01-01

This study demonstrated to synthesis of carbon-free lithium nickel phosphate (LiNiPO4) and its analogue of manganese doped LiNi1−xMnxPO4 (x = 0.05–0.2) cathode materials by a facile polyol method and their suitability for use in high voltage lithium ion batteries (LIBs). The physicochemical...

Diversity of minor elements in olivines from mantle xenoliths (Wołek Hill, SW Poland) - PIXE measurements

Science.gov (United States)

Nowak, Monika; Munnik, Frans; Michalak, Przemysław P.; Renno, Axel

2016-04-01

Wołek Hill is one of the best examined exposures of Cenozoic volcanic rocks from SW Poland (Nowak, 2012). This is related with two facts: a great amount of mantle xenoliths were collected from that outcrop and this is one of two occurrences in Poland were modal metasomatism (related with amphibole crystals presence) was recognized. Wołek Hill is a relatively small exposure and belongs to the Złotoryja Volcanic Field, which is one of the volcanic concentrations in the Polish part of the Central European Volcanic Province (Ladenberger et al. 2006). Based on previous observations olivine crystals from the inside part of xenoliths occasionally display internal inhomogeneity visible on a BSE image. Such inhomogeneity has been related to olivine "sub-grains" with slightly shifted crystal axis. Those "sub-grains" are visible in optical microscope as transitional lamellae (Nowak, Stawikowski 2009). Besides the mentioned visible inhomogeneity olivine crystals also show diversity in Ca content inside single crystals (sometimes even more than 200 ppm). EPMA standard measurements (15 kV, 20 nA, time: 40 seconds) were limited to beam size and detection limits of the microprobe (most of the obtained results oscillate close to the detection limits - or even below it). Special conditions EPMA analyses (15 kV, 100nA, time: 100s) confirmed the differences in Ca content in the studied olivines, but did not provide any idea on how to interpret the results (Nowak, 2012). In this short summary we present preliminary data of olivine minor element composition (Ca, Zn, Cr, Ti, Co, K and also Mn, Ni, Fe) obtained with Particle Induced X-ray Emission(PIXE) measurements performed at the HZDR in Dresden using a 3 MeV proton beam, 1-1.5 nA current and an acquisition time of 3 hrs for each scan. The size of individual scans varied from ca. 30 μm up to 60-65 μm, with 8 x 8 measurement points - min. 4 μm in diameter. The measurements have been analysed with the GeoPIXE software (Ryan, 2001

Radical-induced dephosphorylation of fructose phosphates in aqueous solution

International Nuclear Information System (INIS)

Zegota, H.; Sonntag, C. von

1981-01-01

Oxygen free N 2 O-saturated aqueous solutions of D-fructose-1-phosphate and D-fructose-6-phosphate were γ-irradiated. Inorganic phosphate and phosphate free sugars (containing four to six carbon atoms) were identified and their G-values measured. D-Fructose-1-phosphate yields (G-values in parentheses) inorganic phosphate (1.6), hexos-2-ulose (0.12), 6-deoxy-2,5-hexodiulose (0.16), tetrulose (0.05) and 3-deoxytetrulose (0.15). D-Fructose-6-phosphate yields inorganic phosphate (1.7), hexos-5-ulose (0.1), 6-deoxy-2,5-hexodiulose (0.36), 3-deoxy-2,5-hexodiulose and 2-deoxyhexos-5-ulose (together 0.18). On treatment with alkaline phosphatase further deoxy sugars were recognized and in fructose-1-phosphate G(6-deoxy-2,5-hexodiulose) was increased to a G-value of 0.4. Dephosphorylation is considered to occur mainly after OH attack at C-5 and C-1 in fructose-1-phosphate and at C-5 and C-6 in fructose-6-phosphate. Reaction mechanisms are discussed. (orig.)

Direct observation of grafting interlayer phosphate in Mg/Al layered double hydroxides

International Nuclear Information System (INIS)

Shimamura, Akihiro; Kanezaki, Eiji; Jones, Mark I.; Metson, James B.

2012-01-01

The grafting of interlayer phosphate in synthetic Mg/Al layered double hydroxides with interlayer hydrogen phosphate (LDH-HPO 4 ) has been studied by XRD, TG/DTA, FT-IR, XPS and XANES. The basal spacing of crystalline LDH-HPO 4 decreases in two stages with increasing temperature, from 1.06 nm to 0.82 nm at 333 K in the first transition, and to 0.722 nm at 453 K in the second. The first stage occurs due to the loss of interlayer water and rearrangement of the interlayer HPO 4 2− . In the second transition, the interlayer phosphate is grafted to the layer by the formation of direct bonding to metal cations in the layer, accompanied by a change in polytype of the crystalline structure. The grafted phosphate becomes immobilized and cannot be removed by anion-exchange with 1-octanesulfonate. The LDH is amorphous at 743 K but decomposes to Mg 3 (PO 4 ) 2 , AlPO 4 , MgO and MgAl 2 O 4 after heated to 1273 K. - Graphical abstract: The cross section of the synthetic Mg, Al layered double hydroxides in Phase 1, with interlayer hydrogen phosphate Phase 2, and with grafted phosphate, Phase 3. Highlights: ► The grafting of hydrogen phosphate intercalated Mg/Al-LDH has been studied. ► The basal spacing of crystalline LDH-HPO 4 decreases in two stages with increasing temperature. ► The first decrease is due to loss of interlayer water, the second is attributed to phosphate grafting. ► The grafted interlayer phosphate becomes immobilized and cannot be removed by anion-exchange.

The Oxygen Isotopic Composition of Phosphate: A Tracer for Phosphate Sources and Cycling

Energy Technology Data Exchange (ETDEWEB)

Mclaughlin, K. [Southern California Coastal Water Research Project, Costa Mesa, University of California, CA (United States); Young, M. B.; Paytan, A.; Kendall, C. [U.S. Geological Survey, University of California, CA (United States)

2013-05-15

Phosphorus (P) is a limiting macro-nutrient for primary productivity and anthropogenic P-loading to aquatic ecosystems is one of the leading causes of eutrophication in many ecosystems throughout the world. Because P has only one stable isotope, traditional isotope techniques are not possible for tracing sources and cycling of P in aquatic systems. However, much of the P in nature is bonded to four oxygen (O) atoms as orthophosphate (PO{sub 4}{sup 3-}). The P-O bonds in orthophosphate are strongly resistant to inorganic hydrolysis and do not exchange oxygen with water without biological mediation (enzyme-mediated recycling). Thus, the oxygen isotopic composition of dissolved inorganic phosphate ({delta}{sup 18}O{sub p}) may be used as a tracer for phosphate sources and cycling in aquatic ecosystems. Recently, several studies have been conducted utilizing {delta}{sup 18}O{sub p} as a tracer for phosphate sources and cycling in various aquatic environments. Specifically, work to date indicates that {delta}{sup 18}O{sub p} is useful for determining sources of phosphate to aquatic systems if these sources have unique isotopic signatures and phosphate cycling within the system is limited compared to input fluxes. In addition, because various processes imprint specific fractionation effects, the {delta}{sup 18}O{sub p} tracer can be utilized to determine the degree of phosphorous cycling and processing through the biomass. This chapter reviews several of these studies and discusses the potential to utilize the {delta}{sup 18}O{sub p} of phosphate in rivers and streams. (author)

Enhanced phosphate selectivity from wastewater using copper-loaded chelating resin functionalized with polyethylenimine.

Science.gov (United States)

An, Byungryul; Nam, Juhee; Choi, Jae-Woo; Hong, Seok-Won; Lee, Sang-Hyup

2013-11-01

In water and wastewater, phosphate is considered a critical contaminant due to cause algae blooms and eutrophication. To meet the stringent regulation of phosphate in water, a new commercial chelating resin functionalized with polyethylenimine was tested for phosphate removal by loading Cu(2+) and Fe(2+)/Fe(3+) to enhance selectivity for phosphate. Batch and column experiments showed that CR20-Cu exhibited high selectivity for phosphate over other strong anions such as sulfate. The average binary phosphate/nitrate and phosphate/sulfate factors for CR20-Cu were calculated to be 7.3 and 4.8, respectively, which were more than 0.97 and 0.22 for a commercial anion exchanger (AMP16). The optimal pH for the phosphate removal efficiency was determined to be 7. According to the fixed-bed column test, the breakthrough sequence for multiple ions was HPO4(2-)>SO4(2-)>NO3(-)>Cl(-). Saturated CR20-Cu can be regenerated using 4% NaCl at pH 7. More than 95% of the phosphate from CR20-Cu was recovered, and the phosphate uptake capacity for CR20-Cu was not reduced after 7 regeneration cycles. Copyright © 2013 Elsevier Inc. All rights reserved.

Sorption of phosphate onto calcite; results from batch experiments and surface complexation modeling

DEFF Research Database (Denmark)

Sø, Helle Ugilt; Postma, Dieke; Jakobsen, Rasmus

2011-01-01

The adsorption of phosphate onto calcite was studied in a series of batch experiments. To avoid the precipitation of phosphate-containing minerals the experiments were conducted using a short reaction time (3h) and low concentrations of phosphate (⩽50μM). Sorption of phosphate on calcite was stud......The adsorption of phosphate onto calcite was studied in a series of batch experiments. To avoid the precipitation of phosphate-containing minerals the experiments were conducted using a short reaction time (3h) and low concentrations of phosphate (⩽50μM). Sorption of phosphate on calcite...... of a high degree of super-saturation with respect to hydroxyapatite (SIHAP⩽7.83). The amount of phosphate adsorbed varied with the solution composition, in particular, adsorption increases as the CO32- activity decreases (at constant pH) and as pH increases (at constant CO32- activity). The primary effect...... of ionic strength on phosphate sorption onto calcite is its influence on the activity of the different aqueous phosphate species. The experimental results were modeled satisfactorily using the constant capacitance model with >CaPO4Ca0 and either >CaHPO4Ca+ or >CaHPO4- as the adsorbed surface species...

Phosphate homeostasis in Bartter syndrome: a case-control study.

Science.gov (United States)

Bettinelli, Alberto; Viganò, Cristina; Provero, Maria Cristina; Barretta, Francesco; Albisetti, Alessandra; Tedeschi, Silvana; Scicchitano, Barbara; Bianchetti, Mario G

2014-11-01

Bartter patients may be hypercalciuric. Additional abnormalities in the metabolism of calcium, phosphate, and calciotropic hormones have occasionally been reported. The metabolism of calcium, phosphate, and calciotropic hormones was investigated in 15 patients with Bartter syndrome and 15 healthy subjects. Compared to the controls, Bartter patients had significantly reduced plasma phosphate {mean [interquartile range]:1.29 [1.16-1.46] vs. 1.61 [1.54-1.67] mmol/L} and maximal tubular phosphate reabsorption (1.16 [1.00-1.35] vs. 1.41 [1.37-1.47] mmol/L) and significantly increased parathyroid hormone (PTH) level (6.1 [4.5-7.7] vs. 2.8 [2.2-4.4] pmol/L). However, patients and controls did not differ in blood calcium, 25-hydroxyvitamin D, alkaline phosphatase, and osteocalcin levels. In patients, an inverse correlation (P Bartter patients.

Hanford phosphate precipitation filtration process evaluation

International Nuclear Information System (INIS)

Walker, B.W.; McCabe, D.J.

1997-01-01

The purpose of this filter study was to evaluate cross-flow filtration as effective solid-liquid separation technology for treating Hanford wastes, outline operating conditions for equipment, examine the expected filter flow rates, and determine proper cleaning. A proposed Hanford waste pre-treatment process uses sodium hydroxide at high temperature to remove aluminum from sludge. This process also dissolves phosphates. Upon cooling to 40 degrees centigrade the phosphates form a Na7(PO4)2F9H2O precipitate which must be removed prior to further treatment. Filter studies were conducted with a phosphate slurry simulant to evaluate whether 0.5 micron cross-flow sintered metal Mott filters can separate the phosphate precipitate from the wash solutions. The simulant was recirculated through the filters at room temperature and filtration performance data was collected

Fourier transform Raman spectroscopy of synthetic and biological calcium phosphates.

Science.gov (United States)

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

1994-05-01

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

The variable charge of andisols as affected by nanoparticles of rock phosphate and phosphate solubilizing bacteria

Science.gov (United States)

Arifin, M.; Nurlaeny, N.; Devnita, R.; Fitriatin, B. N.; Sandrawati, A.; Supriatna, Y.

2018-02-01

Andisols has a great potential as agriculture land, however, it has a high phosphorus retention, variable charge characteristics and high value of zero net charge or pH0. The research is aimed to study the effects of nanoparticles of rock phosphate (NPRP) and biofertilizer (phosphate solubilizing bacteria/PSB) on soil pH, pHo (zero point of charge, ZPC) and organic-C in one subgroup of Andisols, namely Acrudoxic Durudands, Ciater Region West Java. The research was conducted from October 2016 to February 2017 in Soil Physics Laboratory and Laboratory of Soil Chemistry and Fertility, Soil Science Department, Faculty of Agriculture, Universitas Padjadjaran. This experiment used a completely randomized factorial design, consisting of two factors and three replications. The first factor was nanoparticles of rock phosphate consist of 4 doses 0; 25; 50 and 75 g/1 kg soil and the second factor was biofertilizer dose consist of g/1 kg soil and without biofertilizer. Total treatment combinations were 8 with 3 replications, so there were 24 experimental plots. The results showed that in general NPRR and biofertilizer will decrease the value of soil pH throughout the incubation periods. There is an interaction between nanoparticles of rock phosphate and biofertilizer in decreasing pHo in the first month of incubation, but after 4-month incubation period, NPRP increased. Interaction between 75 g nanoparticles of rock phosphate with 1 g biofertilizer/1 kg soil in fourth months of incubation decreased soil organic-C to 3.35%.

A model of chemical etching of olivine in the vicinity of the trajectory of a swift heavy ion

Energy Technology Data Exchange (ETDEWEB)

Gorbunov, S.A., E-mail: s.a.gorbunov@mail.ru [Lebedev Physical Institute of the Russian Academy of Sciences, Leninskij pr. 53, 119991 Moscow (Russian Federation); Rymzhanov, R.A. [Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation); Starkov, N.I. [Lebedev Physical Institute of the Russian Academy of Sciences, Leninskij pr. 53, 119991 Moscow (Russian Federation); Volkov, A.E. [Lebedev Physical Institute of the Russian Academy of Sciences, Leninskij pr. 53, 119991 Moscow (Russian Federation); Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation); National Research Centre ‘Kurchatov Institute’, Kurchatov Sq. 1, 123182 Moscow (Russian Federation); Malakhov, A.I. [Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation)

2015-12-15

Searching of superheavy elements, the charge spectra of heavy nuclei in Galactic Cosmic Rays was investigated within the OLYMPIA experiment using the database of etched ion tracks in meteorite olivine. Etching results in the formation of hollow syringe-like channels with diameters of 1–10 μm along the trajectories of these swift heavy ions (SHI). According to the activated complex theory, the local chemical activity is determined by an increase of the specific Gibbs energy of the lattice stimulated by structure transformations, long-range elastic fields, and interatomic bonds breaking generated in the vicinity of the ion trajectory. To determine the dependencies of the Gibbs free energy increase in SHI tracks in olivine on the mass, energy and charge of a projectile, we apply a multiscale model of excitation and relaxation of materials in the vicinity of the SHI trajectory (SHI tracks). Effect of spreading of fast electrons from the ion trajectory causing neutralization of metallic atoms resulting in an increase of the chemical activity of olivine at long distances from the ion trajectory (up to 5 μm) is estimated and discussed.

Interfacial Precipitation of Phosphate on Hematite and Goethite

Directory of Open Access Journals (Sweden)

Lijun Wang

2018-05-01

Full Text Available Adsorption and subsequent precipitation of dissolved phosphates on iron oxides, such as hematite and goethite, is of considerable importance in predicting the bioavailability of phosphates. We used in situ atomic force microscopy (AFM to image the kinetic processes of phosphate-bearing solutions interacting with hematite or goethite surfaces. The nucleation of nanoparticles (1.0–4.0 nm in height of iron phosphate (Fe(III-P phases, possibly an amorphous phase at the initial stages, was observed during the dissolution of both hematite and goethite at the earliest crystallization stages. This was followed by a subsequent aggregation stage where larger particles and layered precipitates are formed under different pH values, ionic strengths, and organic additives. Kinetic analysis of the surface nucleation of Fe-P phases in 50 mM NH4H2PO4 at pH 4.5 showed the nucleation rate was greater on goethite than hematite. Enhanced goethite and hematite dissolution in the presence of 10 mM AlCl3 resulted in a rapid increase in Fe-P nucleation rates. A low concentration of citrate promoted the nucleation, whereas nucleation was inhibited at higher concentrations of citrate. By modeling using PHREEQC, calculated saturation indices (SI showed that the three Fe(III-P phases of cacoxenite, tinticite, and strengite may be supersaturated in the reacted solutions. Cacoxenite is predicted to be more thermodynamically favorable in all the phosphate solutions if equilibrium is reached with respect to hematite or goethite, although possibly only amorphous precipitates were observed at the earliest stages. These direct observations at the nanoscale may improve our understanding of phosphate immobilization in iron oxide-rich acid soils.

Kinetics of strontium sorption in calcium phosphate

International Nuclear Information System (INIS)

Bacic, S.; Komarov, V.F.; Vukovic, Z.

1989-01-01

Kinetics of strontium sorption by highly dispersed solids: tricalcium phosphate (Ca 3 (PO 4 ) 2 , TCP) and hydroxyapatite (Ca 5 (PO 4 ) 3 )H, HAP) were investigated. Analysis of sorption data was made taking into consideration composition and morphology of ultra micro particles. Conclusion is that the isomorphous strontium impurity is structurally sensitive element for calcium phosphate. It was determined that the beginning of strontium desorption corresponds to the beginning of transformation of the TCP - HAP (author)

A dose-escalation study of combretastatin A4-phosphate in healthy dogs.

Science.gov (United States)

Abma, E; Smets, P; Daminet, S; Cornelis, I; De Clercq, K; Ni, Y; Vlerick, L; de Rooster, H

2018-03-01

Combretastatin A4-Phosphate (CA4P) is a vascular disrupting agent revealing promising results in cancer treatments for humans. The aim of this study was to investigate the safety and adverse events of CA4P in healthy dogs as a prerequisite to application of CA4P in dogs with cancer. Ten healthy dogs were included. The effects of escalating doses of CA4P on physical, haematological and biochemical parameters, systolic arterial blood pressure, electrocardiogram, echocardiographic variables and general wellbeing were characterised. Three different doses were tested: 50, 75 and 100 mg m -2 . At all 3 CA4P doses, nausea, abdominal discomfort as well as diarrhoea were observed for several hours following administration. Likewise, a low-grade neutropenia was observed in all dogs. Doses of 75 and 100 mg m -2 additionally induced vomiting and elevation of serum cardiac troponine I levels. At 100 mg m -2 , low-grade hypertension and high-grade neurotoxicity were also observed. In healthy dogs, doses up to 75 mg m -2 seem to be well tolerated. The severity of the neurotoxicity observed at 100 mg m -2 , although transient, does not invite to use this dose in canine oncology patients. © 2017 John Wiley & Sons Ltd.

Corona textures in Proterozoic olivine melanorites of the equeefa suite, Natal metamorphic province, South-Africa

CSIR Research Space (South Africa)

Grantham, GH

1993-01-01

Full Text Available took place during a prolonged history of cooling and partial hydration of the magmatic olivine melanorites from over 1000-degrees-C down to approximately 600-degrees-C. The P-T conditions indicated by the reactions suggest this cooling process...

Ab initio identification of the Li-rich phase in LiFePO4.

Science.gov (United States)

Zeng, Hua; Gu, Yue; Teng, Gaofeng; Liu, Yimeng; Zheng, Jiaxin; Pan, Feng

2018-06-27

A recent discovery of anionic redox activity in Li-rich layered compounds opens a new direction for the design of high-capacity cathode materials for lithium-ion batteries. Here using extensive ab initio calculations, the thermodynamic existence of the Li-rich phase in LiFePO4 to form Li1+xFe1-xPO4 with x not exceeding 12.5% has been proved. Anionic redox activity and structural stability during delithiation are further investigated. Interestingly, it is found that Li1+xFe1-xPO4 cannot be delithiated completely and thus cannot achieve extra capacity by anionic redox activity, because the local oxygen-ion redox will cause the fracture of the rigid framework formed by phosphate tetrahedral polyanions. Although an extra capacity cannot be realized, the excess Li-ions at Fe sites can enhance the Li-ion diffusivity along the adjacent [010] channel and contribute to the shift from 1D to 2D/3D diffusion. This study provides a fresh perspective on olivine-type LiFePO4 and offers some important clues on designing Li-rich cathode materials with high energy density.

Inhibition Effect of 1-Butyl-4-Methylpyridinium Tetrafluoroborate on the Corrosion of Copper in Phosphate Solutions

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M. Scendo

2011-01-01

Full Text Available The influence of the concentration of 1-Butyl-4-methylpyridinium tetrafluoroborate (4MBPBF4 as ionic liquid (IL on the corrosion of copper in 0.5 M PO43− solutions of pH 2 and 4 was studied. The research involved electrochemical polarization method, and scanning electron microscopy (SEM technique. The results obtained showed that the inhibition efficiency of corrosion of copper increases with an increase in the concentration of 4MBPBF4 but decreases with increasing temperature. The thermodynamic functions of corrosion analysis and adsorptive behavior of 4MBPBF4 were carried out. During the test, the adsorption of the inhibitor on the copper surface in the phosphate solutions was found to obey the Langmuir adsorption isotherm and had a physical mechanism.

Reduction of nucleotides by ionizing radiation: uridine 5' phosphate, and cytidine 3' phosphate

International Nuclear Information System (INIS)

Box, H.C.; Potter, W.R.; Budzinski, E.E.

1974-01-01

Anions formed by the addition of an electron to the uracil base were observed in single crystals of the barium salt of uridine 5' phosphate x irradiated at 4.2 0 K. The hyperfine coupling tensor for the C 6 -H proton was deduced from ENDOR measurements; the principal values are -59.12, -32.92 and -16.24 MHz. Similar measurements were made on single crystals of cytidine 3' phosphate. The principal values for the C 6 -H proton hyperfine coupling in the anion formed on the cytosine base are -59.26, -33.98 and -14.68 MHz. (U.S.)

Influence of protonation or alkylation of the phosphate group on the e. s. r. spectra and on the rate of phosphate elimination from 2-methoxyethyl phosphate 2-yl radicals. [. gamma. rays

Energy Technology Data Exchange (ETDEWEB)

Behrens, G; Koltzenburg, G; Ritter, A; Schulte-Frohlinde, D [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany, F.R.). Inst. fuer Strahlenchemie

1978-02-01

The e.s.r. spectra of l-yl, 2-yl and 3'-yl methoxethyl phosphate radicals derived from CH/sub 3/OCH/sub 2/CH/sub 2/-OPO/sub 3/H/sub 2/ by hydrogen abstraction have been measured in aqueous solutions and the hyperfine constants determined. The coupling constants vary strongly with protonation or alkylation of the phosphate group. The 2-yl radicals eliminate phosphate. The rate-constants for the elimination (ksub(e)) have been estimated by e.s.r. measurements and by product studies as a function of pH using /sup 60/Co ..gamma..-radiolysis. The ksub(e) values vary from approximately 0.3 s/sup -1/ for the CH/sub 3/OCHCH/sub 2/OPO/sub 3//sup - -/ radical and approximately 10/sup 3/s/sup -1/ for CH/sub 3/OCHCH/sub 2/OPO/sub 3/H/sup -/, to approximately 3 x 10/sup 6/s/sup -1/ for CH/sub 3/OCHCH/sub 2/OPO/sub 3/H/sub 2/. Alkylation of the phosphate group increased the elimination rate-constant to a similar extent as protonation. The results support a recent mechanism which described the OH-radical-induced single-strand breaks of DNA in aqueous solution starting from the C-4' radical of the sugar moiety. It is further concluded the C-4' radical of DNA eliminates the 3'-phosphate group faster than the 5'-phosphate group.

Dental Composites with Calcium / Strontium Phosphates and Polylysine.

Directory of Open Access Journals (Sweden)

Piyaphong Panpisut

Full Text Available This study developed light cured dental composites with added monocalcium phosphate monohydrate (MCPM, tristrontium phosphate (TSrP and antimicrobial polylysine (PLS. The aim was to produce composites that have enhanced water sorption induced expansion, can promote apatite precipitation and release polylysine.Experimental composite formulations consisted of light activated dimethacrylate monomers combined with 80 wt% powder. The powder phase contained a dental glass with and without PLS (2.5 wt% and/or reactive phosphate fillers (15 wt% TSrP and 10 wt% MCPM. The commercial composite, Z250, was used as a control. Monomer conversion and calculated polymerization shrinkage were assessed using FTIR. Subsequent mass or volume changes in water versus simulated body fluid (SBF were quantified using gravimetric studies. These were used, along with Raman and SEM, to assess apatite precipitation on the composite surface. PLS release was determined using UV spectroscopy. Furthermore, biaxial flexural strengths after 24 hours of SBF immersion were obtained.Monomer conversion of the composites decreased upon the addition of phosphate fillers (from 76 to 64% but was always higher than that of Z250 (54%. Phosphate addition increased water sorption induced expansion from 2 to 4% helping to balance the calculated polymerization shrinkage of ~ 3.4%. Phosphate addition promoted apatite precipitation from SBF. Polylysine increased the apatite layer thickness from ~ 10 to 20 μm after 4 weeks. The novel composites showed a burst release of PLS (3.7% followed by diffusion-controlled release irrespective of phosphate addition. PLS and phosphates decreased strength from 154 MPa on average by 17% and 18%, respectively. All formulations, however, had greater strength than the ISO 4049 requirement of > 80 MPa.The addition of MCPM with TSrP promoted hygroscopic expansion, and apatite formation. These properties are expected to help compensate polymerization shrinkage and

Expression of yeast lipid phosphatase Sac1p is regulated by phosphatidylinositol-4-phosphate

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Mayinger Peter

2008-01-01

Full Text Available Abstract Background Phosphoinositides play a central role in regulating processes at intracellular membranes. In yeast, a large number of phospholipid biosynthetic enzymes use a common mechanism for transcriptional regulation. Yet, how the expression of genes encoding lipid kinases and phosphatases is regulated remains unknown. Results Here we show that the expression of lipid phosphatase Sac1p in the yeast Saccharomyces cerevisiae is regulated in response to changes in phosphatidylinositol-4-phosphate (PI(4P concentrations. Unlike genes encoding enzymes involved in phospholipid biosynthesis, expression of the SAC1 gene is independent of inositol levels. We identified a novel 9-bp motif within the 5' untranslated region (5'-UTR of SAC1 that is responsible for PI(4P-mediated regulation. Upregulation of SAC1 promoter activity correlates with elevated levels of Sac1 protein levels. Conclusion Regulation of Sac1p expression via the concentration of its major substrate PI(4P ensures proper maintenance of compartment-specific pools of PI(4P.

Aqueous phosphate removal using nanoscale zero-valent iron

International Nuclear Information System (INIS)

Almeelbi, Talal; Bezbaruah, Achintya

2012-01-01

Nanoscale zero-valent iron (NZVI) particles have been used for the remediation of a wide variety of contaminants. NZVI particles have high reactivity because of high reactive surface area. In this study, NZVI slurry was successfully used for phosphate removal and recovery. Batch studies conducted using different concentrations of phosphate (1, 5, and 10 mg PO 4 3− -P/L with 400 mg NZVI/L) removed ∼96 to 100 % phosphate in 30 min. Efficacy of the NZVI in phosphate removal was found to 13.9 times higher than micro-ZVI (MZVI) particles with same NZVI and MZVI surface area concentrations used in batch reactors. Ionic strength, sulfate, nitrate, and humic substances present in the water affected in phosphate removal by NZVI but they may not have any practical significance in phosphate removal in the field. Phosphate recovery batch study indicated that better recovery is achieved at higher pH and it decreased with lowering of the pH of the aqueous solution. Maximum phosphate recovery of ∼78 % was achieved in 30 min at pH 12. The successful rapid removal of phosphate by NZVI from aqueous solution is expected to have great ramification for cleaning up nutrient rich waters.

Liming effect on P availability from Maardu phosphate rock

International Nuclear Information System (INIS)

Sidlauskas, G.; Masauskas, S.; Ezerinskas, V.

2002-01-01

Thirty years ago phosphate rock from the Maardu deposit was intensively used for soil fertilization in Lithuania. However, the application of finely ground product caused an undesirable dusty operation. Afterwards, a super-phosphate production plant was built in Kedainiai and the use of phosphate rock was completely abandoned. Field experiments with fodder beets and barley were carried out to evaluate the P availability of granulated superphosphate and Maardu phosphate rock. The comparison was made at three acidity levels: a) unlimed acid soil with a high content of Al (pH kcl 4.3-4.4, hydrolytic acidity was 41-44 meq/kg soil), b) soil limed with 0.5n rate CaCO 3 powder limestone based on hydrolytic acidity, and c) soil limed with 1.0n rate CaCO 3 . Two field experiments were carried out with fodder beets. In 1997 the yield increased significantly due to liming. However, no significant yield increases were found due to the application of phosphorus fertilizers. Differences between the effect of superphosphate and phosphate rock were also not observed. This might have been caused by a severe drought during the vegetative growth of plants. In the following year, 1998, a soil with similar acidity was chosen, however it contained even lower amounts of available phosphorus in the arable soil (about 50 mg/kg soil A-L method). In the unlimed soil the yield was low, the effect of superphosphate was better than that of phosphate rock. A good fodder beet yield of 32 to 35 t/ha was obtained and the effect of phosphate rock was better than that of superphosphate at 0.5n CaCO 3 rate. When liming with at the high rate (1.0n CaCO 3 rate according to hydrolytic acidity) the action of phosphate rock declined, and a better yield was obtained with superphosphate. Barley was grown after fodder beets in the 1997 experimental field and the residual effect of superphosphate and phosphate rock was investigated. Weather conditions were favorable for barley growth. Therefore a normal yield

The structural response of gadolinium phosphate to pressure

International Nuclear Information System (INIS)

Heffernan, Karina M.; Ross, Nancy L.; Spencer, Elinor C.; Boatner, Lynn A.

2016-01-01

Accurate elastic constants for gadolinium phosphate (GdPO 4 ) have been measured by single-crystal high-pressure diffraction methods. The bulk modulus of GdPO 4 determined under hydrostatic conditions, 128.1(8) GPa (K′=5.8(2)), is markedly different from that obtained with GdPO 4 under non-hydrostatic conditions (160(2) GPa), which indicates the importance of shear stresses on the elastic response of this phosphate. High pressure Raman and diffraction analysis indicate that the PO 4 tetrahedra behave as rigid units in response to pressure and that contraction of the GdPO 4 structure is facilitated by bending/twisting of the Gd–O–P links that result in increased distortion in the GdO 9 polyhedra. - Graphical abstract: A high-pressure single crystal diffraction study of GdPO 4 with the monazite structure is presented. The elastic behaviour of rare-earth phosphates are believed to be sensitive to shear forces. The bulk modulus of GdPO 4 measured under hydrostatic conditions is 128.1(8) GPa. Compression of the structure is facilitated by bending/twisting of the Gd−O−P links that result in increased distortion in the GdO 9 polyhedra. Display Omitted - Highlights: • The elastic responses of rare-earth phosphates are sensitive to shear forces. • The bulk modulus of GdPO 4 measured under hydrostatic conditions is 128.1(8) GPa. • Twisting of the inter-polyhedral links allows compression of the GdPO 4 structure. • Changes to the GdO 9 polyhedra occur in response to pressure (<7.0 GPa).

Adsorption of Phosphate Ion in Water with Lithium-Intercalated Gibbsite

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Riwandi Sihombing

2015-12-01

Full Text Available In order to enhance adsorption capacity of gibbsite (Al(OH3 as an adsorbent for the adsorption of phosphate in water, gibbsite was modified through lithium-intercalation. The purification method of Tributh and Lagaly was applied prior to intercalation. The Li-Intercalation was prepared by the dispersion of gibbsite into LiCl solution for 24 hours. This intercalation formed an cationic clay with the structure of [LiAl2(OH6]+ and exchangeable Cl- anions in the gibbsite interlayer. A phosphate adsorption test using Lithium-intercalated gibbsite (LIG resulted in optimum adsorption occurring at pH 4.5 with an adsorption capacity of 11.198 mg phosphate/g LIG which is equivalent with 1.04 wt% LIG. The adsorption capacity decreased with decreasing amounts of H2PO4-/HPO4- species in the solution. This study showed that LIG has potential as an adsorbent for phosphate in an aqueous solution with pH 4.5–9.5.

Are Polyphosphates or Phosphate Esters Prebiotic Reagents?

Science.gov (United States)

Keefe, Anthony D.; Miller, Stanley L.

1995-01-01

It is widely held that there was a phosphate compound in prebiotic chemistry that played the role of adenosine triphosphate and that the first living organisms had ribose-phosphate in the backbone of their genetic material. However, there are no known efficient prebiotic synthesis of high-energy phosphates or phosphate esters. We review the occurrence of phosphates in nature, the efficiency of the volcanic synthesis of P4O10, the efficiency of polyphosphate synthesis by heating phosphate minerals under geological conditions, and the use of high-energy organic compounds such as cyanamide or hydrogen cyanide. These are shown to be inefficient processes especially when the hydrolysis of the polyphosphates is taken into account. For example, if a whole atmosphere of methane or carbon monoxide were converted to cyanide which somehow synthesized polyphosphates quantitatively, the polyphosphate concentration in the ocean would still have been insignificant. We also attempted to find more efficient high-energy polymerizing agents by spark discharge syntheses, but without success. There may still be undiscovered robust prebiotic syntheses of polyphosphates, or mechanisms for concentrating them, but we conclude that phosphate esters may not have been constituents of the first genetic material. Phosphoanhydrides are also unlikely as prebiotic energy sources.

Interaction between calcium and phosphate adsorption on goethite

NARCIS (Netherlands)

Rietra, R.P.J.J.; Hiemstra, T.; Riemsdijk, van W.H.

2001-01-01

Quantitatively, little is known about the ion interaction processes that are responsible for the binding of phosphate in soil, water, and sediment, which determine the bioavailability and mobility of phosphate. Studies have shown that metal hydroxides are often responsible for the binding of PO4 in

The role of inorganic phosphate in intact human erythrocytes

International Nuclear Information System (INIS)

Nishiguchi, Eiko; Umeda, Masahiro.

1988-01-01

The role of inorganic phosphate in intact human erythrocytes was investigated by phosphorus-31 nuclear magnetic resonance ( 31 P NMR). When erythrocytes stored for 5 weeks were incubated at 37 deg C, pH 7.4, in medium containing 2 mM adenine and 10 mM inosine, with or without 5 mM glucose, a substance of around 4 ppm, as assessed by 31 P NMR chemical shift, was detected in the mixture. However, this substance disappeared by the addition of inorganic phosphate. When erythrocytes stored for 4 weeks in acid citrate dextrose (ACD) solution were incubated with 2 mM adenine, 10 mM inosine, 5 mM glucose, 50 mM inorganic phosphate and 10 mM pyruvate at 37 deg C, pH 7.4, the 2,3-DPG level increased gradually, whereas the ATP level initially increased and then decreased. Intracellular inorganic phosphate appeared to be used for the synthesis of ATP and 2,3-DPG during the first 30 min. of the reaction. These results suggests that the inorganic phosphate accelerates glycolysis by increasing the activity of glycolytic enzymes rather than its direct involvement in synthesizing organic phosphorus compounds in stored erythrocytes. The results also suggests that the reserve energy from ATP synthesis is not sufficient for the synthesis of 2,3-DPG. (author)

TIE2-expressing macrophages limit the therapeutic efficacy of the vascular disrupting agent, combretastatin A4 phosphate in mice.

OpenAIRE

Welford, Abigail F.; Biziato, Daniela; Coffelt, Seth B.; Nucera, Silvia; Fisher, Matthew; Pucci, Ferdinando; Di Serio, Clelia; Naldini, Luigi; De Palma, Michele; Tozer, Gillian M.; Lewis, Claire E.

2011-01-01

Vascular-disrupting agents (VDAs) such as combretastatin A4 phosphate (CA4P) selectively disrupt blood vessels in tumors and induce tumor necrosis. However, tumors rapidly repopulate after treatment with such compounds. Here, we show that CA4P-induced vessel narrowing, hypoxia, and hemorrhagic necrosis in murine mammary tumors were accompanied by elevated tumor levels of the chemokine CXCL12 and infiltration by proangiogenic TIE2-expressing macrophages (TEMs). Inhibiting TEM recruitment to CA...

Storage of CO2 by mineral carbonation of olivine: Study of the global process for the recovery of the reaction products and the separation of chromite particles by flotation

International Nuclear Information System (INIS)

Turri, Laura

2017-01-01

This work deals with the study of direct carbonation of olivine in solution, for the chemical transformation of CO 2 emitted by the industries. The influence of operating conditions is evaluated in order to optimize the yield of the reaction. However, for environmental acceptability and economic viability of the project, the beneficiation of recoverable metals and products is considered. Chromite particles contained in olivine are unreactive during the carbonation reaction: the separation is developed by flotation upstream of the reaction. According to the results, the extraction of chromite by magnetic separation is also conceivable. Gravimetric separation by sedimentation is considered to recover residual olivine in the reaction products, in order to recycle them in the carbonation process. Products sieving allowed to concentrate carbonates (less than 40 μm) and silica (between 40 and 106 μm). However, the co-precipitation of mixed carbonates due to the presence of iron and nickel included in the magnesium matrix, compromises the purification and the optimal valorization of the solids. Moreover, the formation of a passivation layer on the particles surface limits the conversion of olivine. Pretreatment of olivine is envisaged for the leaching of nickel in ammoniac solution. Besides, preliminary dissolution of olivine and selective precipitation of species with pH control of the solution can be an interesting alternative for higher carbonation extent and more efficient purification of the products. (author)

Geochemistry and oxygen isotope composition of main-group pallasites and olivine-rich clasts in mesosiderites

DEFF Research Database (Denmark)

Greenwood, Richard C.; Barrat, Jean-Alix; Scott, Edward R. D.

2015-01-01

origin. Although the Dawn mission did not detect mesosiderite-like material on Vesta, evidence linking the mesosiderites and HEDs includes: (i) theirnearly identical oxygen isotope compositions; (ii) the presence in both of coarse-grained Mg-rich olivines; (iii) both have synchronous Lu-Hf and Mn-Cr ages...

Phosphate removal from water using lithium intercalated gibbsite.

Science.gov (United States)

Wang, Shan-Li; Cheng, Chia-Yi; Tzou, Yu-Min; Liaw, Ren-Bao; Chang, Ta-Wei; Chen, Jen-Hshuan

2007-08-17

In this study, lithium intercalated gibbsite (LIG) was investigated for its effectiveness at removing phosphate from water and the mechanisms involved. LIG was prepared through intercalating LiCl into gibbsite giving a structure of [LiAl2(OH)6]+ layers with interlayer Cl- and water. The results of batch adsorption experiments showed that the adsorption isotherms at various pHs exhibited an L-shape and could be fitted well using the Langmuir model. The Langmuir adsorption maximum was determined to be 3.0 mmol g(-1) at pH 4.5 and decreased with increasing pH. The adsorption of phosphate was mainly through the displacement of the interlayer Cl- ions in LIG. In conjunction with the anion exchange reaction, the formation of surface complexes or precipitates could also readily occur at lower pH. The adsorption decreased with increasing pH due to decreased H(2)PO(4)(-)/HPO4(2-) molar ratio in solution and positive charges on the edge faces of LIG. Anion exchange is a fast reaction and can be completed within minutes; on the contrary, surface complexation is a slow process and requires days to reach equilibrium. At lower pH, the amount of adsorbed phosphate decreased significantly as the ionic strength was increased from 0.01 to 0.1M. The adsorption at higher pH showed high selectivity toward divalent HPO4(2-) ions with an increase in ionic strength having no considerable effect on the phosphate adsorption. These results suggest that LIG may be an effective scavenger for removal of phosphate from water.

Phosphate removal from water using lithium intercalated gibbsite

International Nuclear Information System (INIS)

Wang, S.-L.; Cheng, C.-Y.; Tzou, Y.-M.; Liaw, R.-B.; Chang, T.-W.; Chen, J.-H.

2007-01-01

In this study, lithium intercalated gibbsite (LIG) was investigated for its effectiveness at removing phosphate from water and the mechanisms involved. LIG was prepared through intercalating LiCl into gibbsite giving a structure of [LiAl 2 (OH) 6 ] + layers with interlayer Cl - and water. The results of batch adsorption experiments showed that the adsorption isotherms at various pHs exhibited an L-shape and could be fitted well using the Langmuir model. The Langmuir adsorption maximum was determined to be 3.0 mmol g -1 at pH 4.5 and decreased with increasing pH. The adsorption of phosphate was mainly through the displacement of the interlayer Cl - ions in LIG. In conjunction with the anion exchange reaction, the formation of surface complexes or precipitates could also readily occur at lower pH. The adsorption decreased with increasing pH due to decreased H 2 PO 4 - /HPO 4 2- molar ratio in solution and positive charges on the edge faces of LIG. Anion exchange is a fast reaction and can be completed within minutes; on the contrary, surface complexation is a slow process and requires days to reach equilibrium. At lower pH, the amount of adsorbed phosphate decreased significantly as the ionic strength was increased from 0.01 to 0.1 M. The adsorption at higher pH showed high selectivity toward divalent HPO 4 2- ions with an increase in ionic strength having no considerable effect on the phosphate adsorption. These results suggest that LIG may be an effective scavenger for removal of phosphate from water

Aqueous synthesis of LiFePO4 with Fractal Granularity

Science.gov (United States)

Cabán-Huertas, Zahilia; Ayyad, Omar; Dubal, Deepak P.; Gómez-Romero, Pedro

2016-06-01

Lithium iron phosphate (LiFePO4) electrodes with fractal granularity are reported. They were made from a starting material prepared in water by a low cost, easy and environmentally friendly hydrothermal method, thus avoiding the use of organic solvents. Our method leads to pure olivine phase, free of the impurities commonly found after other water-based syntheses. The fractal structures consisted of nanoparticles grown into larger micro-sized formations which in turn agglomerate leading to high tap density electrodes, which is beneficial for energy density. These intricate structures could be easily and effectively coated with a thin and uniform carbon layer for increased conductivity, as it is well established for simpler microstructures. Materials and electrodes were studied by means of XRD, SEM, TEM, SAED, XPS, Raman and TGA. Last but not least, lithium transport through fractal LiFePO4 electrodes was investigated based upon fractal theory. These water-made fractal electrodes lead to high-performance lithium cells (even at high rates) tested by CV and galvanostatic charge-discharge, their performance is comparable to state of the art (but less environmentally friendly) electrodes.

Preparation and bioactivity of micro-arc oxidized calcium phosphate coatings

International Nuclear Information System (INIS)

Pan, Y.K.; Chen, C.Z.; Wang, D.G.; Lin, Z.Q.

2013-01-01

Calcium phosphate (CaP) coatings were prepared on ZK60 magnesium alloy by micro-arc oxidation (MAO) in electrolyte containing calcium acetate monohydrate (CH 3 COO) 2 Ca·H 2 O) and disodium hydrogen phosphate dodecahydrate (Na 2 HPO 4 ·12H 2 O). Scanning electron microscope (SEM), energy-dispersive X-ray spectrometry (EDX) and X-ray diffractometer (XRD) were employed to characterize the microstructure, elemental distribution and phase composition of the CaP coatings respectively. Simulated body fluid (SBF) immersion test was used to evaluate the coating degradability and bioactivity. After 30 days of SBF immersion, the CaP coatings effectively reduce the degradation rate. The surfaces of CaP coatings are covered by a new layer formed of numerous needle-like, spherical and columned calcium phosphates. SEM, EDX and XRD results suggest that these calcium phosphates are bioactive calcium phosphate phases such as hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 , HA) and calcium pyrophosphates (Ca 2 P 2 O 7 , CPP). The formation of these calcium phosphates indicates that the CaP coatings have bioactivity. - Highlights: • Bioactive CaP coatings are successfully formed on ZK60 magnesium alloy. • CaP coatings consist of MgO, MgF 2 , CaO, CaF 2 and Ca 3 (PO 4 ) 2 . • Needle-like, spherical and columned calcium phosphates formed in SBF. • CaP coatings exhibit bioactivity and low corrosion rate

Uranium recovery in a pilot plant as by product of the phosphate fertilizers

International Nuclear Information System (INIS)

Dantas, C.C.; Santos, F.S.M. dos; Paula, H.C.B.; Santana, A.O. de

1984-01-01

A process was developed and a piloto plant was installed to recovery uranium from chloridric leach liquor of phosphate rocks. The extractor system is a mixture of di(2-ethylhexyl) phosphoric acid (DEHPA) and tributyl-phosphate (TBP) in a kerosene diluent. The phosphate rocks are leached for dicalcium phosphate (CaHPO 4 ) production, by the reactions: Ca 3 (PO 4 ) 2 + 4 HCl → Ca(H 2 PO 4 ) 2 + CaCl 2 and Ca(H 2 PO 4 ) 2 + Ca(OH) 2 → CaHPO 4 + 2 H 2 O. The uranium recovery process comprises the following steps:extraction, scrubbing, reextraction, iron removal and uranium precipitation. The uranium is precipited as ADU with 80% of U 3 O 8 .(Author) [pt

Effect of sucrose, erythrose-4-phosphate and phenylalanine on biomassa and flavonoid content of callus culture from leaves of Gynura procumbens Merr.

Science.gov (United States)

Nurisa, Aryana; Kristanti, Alfinda Novi; Manuhara, Yosephine Sri Wulan

2017-08-01

The aims of this study were to know the effect of concentration of sucrose, erythrose-4-phosphate and phenylalanine on biomass and flavonoid content of callus cultures from leaves of sambung nyawa (Gynura procumbens Merr.). This study was experimental research with complete randomized design. Callus induction was treated in MS medium supplemented with NAA 2 mg/L, BAP 1 mg/L and sucrose concentration (10 g/L, 30 g/L and 50 g/L) respectively were combined with erythrose-4-phosphate (0 µM, 2,5 µM and 5 µM) and phenylalanine (0 mg/L, 2 mg/L and 3 mg/L), each treatment were repeated four times. After six weeks of culture, fresh and dry weight of calli were measured and extracted with ethanol absolut. Crude extract ethanolic of callus was analyzed used by a modified colorimetric with spectrophotometer method. The best yield of calli biomass (0,672 ± 0,112 gram of fresh weight and 0,033 ± 0,009 gram of dry weight) was obtained in treatment of 30 g/L sucrose of and 5 µM erythrose-4-phosphate. The highest total flavonoid content was obtained of calli treated with 30 g/L of sucrose and 3 mg/L of phenylalanine (3633,4 ppm quercetin/gram dry weight and 15777,8 ppm kaempferol/gram dry weight).

Radiological impacts of uranium recovery in the phosphate industry

International Nuclear Information System (INIS)

Ryan, M.T.

1981-01-01

This article characterizes the occupational and public radiological health impacts associated with phosphate mining and milling. These impacts are related to the phosphate industry's uranium production potential and are compared with those associated with conventional uranium mining and milling. The radiological impacts resulting from occupational and nonoccupational exposures are assessed. Occupational exposures in phosphate facilities are compared to background exposures and radiological population dose assessments, which characterize important radionuclides and exposure pathways. The following conclusions were reached: (1) public consequences of phosphate mining will occur whether or not uranium is recovered as a by-product, (2) radiological consequences of phosphate mining may be comparable to those associated with uranium mining and milling per unit uranium production, (3) radiological impacts via surface waterways and crops fertilized with uranium-bearing phosphates are of minor consequence, and (4) major radiological public health problems associated with phosphate mining are related to radon and radon progeny exposures in structures built on reclaimed lands or with phosphate mining residues, although the magnitudes of these impacts are difficult to evaluate with current data

Vanadate influence on metabolism of sugar phosphates in fungus Phycomyces blakesleeanus.

Directory of Open Access Journals (Sweden)

Milan Žižić

Full Text Available The biological and chemical basis of vanadium action in fungi is relatively poorly understood. In the present study, we investigate the influence of vanadate (V5+ on phosphate metabolism of Phycomyces blakesleeanus. Addition of V5+ caused increase of sugar phosphates signal intensities in 31P NMR spectra in vivo. HPLC analysis of mycelial phosphate extracts demonstrated increased concentrations of glucose 6 phosphate, fructose 6 phosphate, fructose 1, 6 phosphate and glucose 1 phosphate after V5+ treatment. Influence of V5+ on the levels of fructose 2, 6 phosphate, glucosamine 6 phosphate and glucose 1, 6 phosphate (HPLC, and polyphosphates, UDPG and ATP (31P NMR was also established. Increase of sugar phosphates content was not observed after addition of vanadyl (V4+, indicating that only vanadate influences its metabolism. Obtained results from in vivo experiments indicate catalytic/inhibitory vanadate action on enzymes involved in reactions of glycolysis and glycogenesis i.e., phosphoglucomutase, phosphofructokinase and glycogen phosphorylase in filamentous fungi.

Effect of Casein Phosphopeptide-Amorphous Calcium Phosphate and Three Calcium Phosphate on Enamel Microhardness.

Science.gov (United States)

Haghgou, En Hr; Haghgoo, Roza; Roholahi, Mohamad R; Ghorbani, Zahra

2017-07-01

This study aims to investigate the effect of casein phos-phopeptide-amorphous calcium phosphate and three calcium phosphate (CPP-ACP and TCP) on increasing the microhardness of human enamel after induction of erosion. A total of 26 healthy human-impacted third molar teeth were chosen, and their hardness measured using a microhardness testing machine. The samples were immersed in Coca Cola (pH = 4.7) for 8 minutes. Then, micro-hardness was measured again, and these samples were randomly divided into four groups (two control groups and two experimental groups). (1) Negative control group: Artificial saliva was used for 10 minutes, (2) positive control group: Fluoride gel was used for 10 minutes, (3) β-TCP group: TCP was used for 10 minutes, (4) CCP-ACP group: CCP-ACP was used for 10 minutes. The final microhardness of those samples was measured, and the changes in microhardness of teeth within group and between groups were analyzed using the paired and analysis of variance tests respectively. Results were considered statistically significant at a level of p < 0.05. No significant difference was observed in microhard-ness between CPP-ACP group and TCP group (p = 0.368) during the time microhardness significantly dropped after soaking in soda. Casein phosphopeptide-amorphous calcium phosphate and TCP increased the microhardness of teeth. The increase in hardness in the TCP group was higher than in the CPP-ACP group, but this difference was not significant (p = 0.36). Casein phosphopeptide-amorphous calcium phosphate and TCP can affect the remineralization of erosive lesions.

21 CFR 184.1697 - Riboflavin-5′-phosphate (sodium).

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Riboflavin-5â²-phosphate (sodium). 184.1697 Section... SAFE Listing of Specific Substances Affirmed as GRAS § 184.1697 Riboflavin-5′-phosphate (sodium). (a) Riboflavin-5′-phosphate (sodium) (C17H20N4O9PNa·2H2O, CAS Reg. No 130-40-5) occurs as the dihydrate in yellow...

In situ oxygen isotope compositions in olivines of different types of cosmic spherules: An assessment of relationships to chondritic particles

Digital Repository Service at National Institute of Oceanography (India)

Rudraswami, N.G.; ShyamPrasad, M.; Jones, R.H.; Nagashima, K.

bearing cosmic spherules (Rudraswami et al., 2015b). In addition, some Mg-rich relict olivine grains are very 16O-rich, with 17O ranging from −21.9 to -18.7‰, similar to oxygen isotopic compositions observed in calcium aluminium rich inclusions (CAIs... isotope analyses of the olivine grains are provided in Appendix B and Table 1, respectively. 5    Four scoriaceous spherules namely, AAS62-61-P64, AAS62-9-P43, AAS62-9-P51 and AAS62-9- P54 were identified for oxygen isotope studies (Fig. 1a...

Effect of molybdate on phosphating of Nd-Fe-B magnets for corrosion protection

Directory of Open Access Journals (Sweden)

Adonis Marcelo Saliba-Silva

2005-06-01

Full Text Available Nd-Fe-B magnets are highly susceptible to corrosion and need protection against environment attack. The use of organic coatings is one of the main methods of corrosion protection of these materials. Data related to the effect of conversion coatings, such as phosphating, on corrosion performance of these magnets is still scarce. Studies about the effect of phosphating on the corrosion resistance of a commercial Nd-Fe-B sintered magnet indicated that it increases the corrosion resistance of these magnets, compared to non-phosphated magnets. In this study, the solution chemistry of a phosphating bath was altered with the addition of molybdate and its effect on the corrosion resistance of magnets investigated. Sintered magnet specimens were phosphated in solutions of 10 g/L NaH2PO4 (pH 3.8, either with or without molybdate [10-3 M MoO4(2-], to improve their corrosion resistance. The effect of phosphating time was also evaluated, and specimens were phosphated for 4 and 18 hours. To evaluate the corrosion performance of phosphated and unphosphated specimens, a corrosion test based on monitoring hydrogen evolution on the surface of the magnets was used. This technique revealed that the addition of molybdate to the phosphating solution improved the corrosion resistance of the magnets phosphated by immersion for short periods but had no beneficial effect if phosphated by immersion for longer periods.

Absorption spectra and speciation of plutonium(VI) with phosphate

Energy Technology Data Exchange (ETDEWEB)

Weger, H.T.; Reed, D.

1996-02-01

Plutonium(VI)-phosphate species in aqueous solution, at pH < 2.4, formed two species: PuO{sub 2}H{sub 2}PO{sub 4}{sup +} (characterized by an 835 nm absorption band) and the solid phase PuO{sub 2}(H{sub 2}PO{sub 4}){sub 2}. The stability constant {beta} for the PuO{sub 2}H{sub 2}PO{sub 4}{sup +} species was determined to be log {beta} = 2.1 {+-} 0.1 (ionic strength = 0.6--0.9 M) and log {beta}{sup T} = 2.6 {+-} 0.15 (zero ionic strength). Four Pu(VI)-phosphate species (absorption bands at 842, 846, 857, and 866 nm) formed at pH = 2.4 to 12.2 and are characterized by polynuclear behavior, the formation of precipitates, and colloidal properties. The 842 and 846 nm species are believed to be [PuO{sub 2}(HPO{sub 4}){sub m}]{sub n} and [PuO{sub 2}(NaPO{sub 4}){sub m}]{sub n}. The 857 and 866 nm species area as yet unidentified. The speciation of plutonium with phosphate is of interest to radionuclide migration studies because phosphate is present in many groundwaters and may be used as an actinide getter in nuclear waste disposal. An actinide getter is a complexing agent that forms insoluble phases with actinides, thereby reducing their migration.

The reduction of nucleotides by ionizing radiation: uridine 5' phosphate and cytidine 3' phosphate

International Nuclear Information System (INIS)

Box, H.C.; Potter, W.R.; Budzinski, E.E.

1975-01-01

Anions formed by the addition of an electron to the uracil base were observed in single crystals of the barium salt of uridine 5' phosphate x-irradiated at 4.2 degreeK. The hyperfine coupling tensor for the C 6 --H proton was deduced from ENDOR measurements; the principal values are -59.12, -32.92, and -16.24 MHz. Similar measurements were made on single crystals of cytidine 3' phosphate. The principal values for the C 6 --H proton hyperfine coupling in the anion formed on the cytosine base are -59.26, -33.98, and -14.68 MHz

Erbium-doped phosphate glass waveguide on silicon with 4.1 dB/cm gain at 1.535 µm

Science.gov (United States)

Yan, Y. C.; Faber, A. J.; de Waal, H.; Kik, P. G.; Polman, A.

1997-11-01

Erbium-doped multicomponent phosphate glass waveguides were deposited by rf sputtering techniques. The Er concentration was 5.3×1020cm-3. By pumping the waveguide at 980 nm with a power of ˜21 mW, a net optical gain of 4.1 dB at 1.535 μm was achieved. This high gain per unit length at low pump power could be achieved because the Er-Er cooperative upconversion interactions in this heavily Er-doped phosphate glass are very weak [the upconversion coefficient is (2.0±0.5)×10-18 cm3/s], presumably due to the homogeneous distribution of Er in the glass and due to the high optical mode confinement in the waveguide which leads to high pump power density at low pump power.

Crystal structures and magnetic properties of iron (III)-based phosphates: Na4NiFe(PO4)3 and Na2Ni2Fe(PO4)3

International Nuclear Information System (INIS)

Essehli, Rachid; Bali, Brahim El; Benmokhtar, Said; Bouziane, Khalid; Manoun, Bouchaib; Abdalslam, Mouner Ahmed; Ehrenberg, Helmut

2011-01-01

Graphical abstract: A perspective view of the Na 2 Ni 2 Fe(PO 4 ) 3 structure along the [0 0 1] direction. Both compounds seem to exibit antiferromagnetic interactions between magnetic entities at low temperature. Display Omitted Research highlights: → Nasicon and Alluaudite compounds, Iron(III)-based phosphates, Crystal structures of Na 4 NiFe(PO 4 ) 3 and Na 2 Ni 2 Fe(PO 4 ) 3 . → Magnetism behaviours of Na 4 NiFe(PO 4 ) 3 and Na 2 Ni 2 Fe(PO 4 ) 3 . → Antiferromagnetism interactions. → Mossbauer spectroscopy. - Abstract: Crystal structures from two new phosphates Na 4 NiFe(PO 4 ) 3 (I) and Na 2 Ni 2 Fe(PO 4 ) 3 (II) have been determined by single crystal X-ray diffraction analysis. Compound (I) crystallizes in a rhombohedral system (S. G: R-3c, Z = 6, a = 8.7350(9) A, c = 21.643(4) A, R 1 = 0.041, wR 2 =0.120). Compound (II) crystallizes in a monoclinic system (S. G: C2/c, Z = 4, a = 11.729(7) A, b = 12.433(5) A, c = 6.431(2) A, β = 113.66(4) o , R 1 = 0.043, wR 2 =0.111). The three-dimensional structure of (I) is closely related to the Nasicon structural type, consisting of corner sharing [(Ni/Fe)O 6 ] octahedra and [PO 4 ] tetrahedra forming [NiFe(PO 4 ) 3 ] 4+ units which align in chains along the c-axis. The Na + cations fill up trigonal antiprismatic sites within these chains. The crystal structure of (II) belongs to the alluaudite type. Its open framework results from [Ni 2 O 10 ] units of edge-sharing [NiO 6 ] octahedra, which alternate with [FeO 6 ] octahedra that form infinite chains. Coordination of these chains yields two distinct tunnels in which site Na + . The magnetization data of compound (I) reveal antiferromagnetic (AFM) interactions by the onset of deviations from a Curie-Weiss behaviour at low temperature as confirmed by Moessbauer measurements performed at 4.2 K. The corresponding temperature dependence of the reciprocal susceptibility χ -1 follows a typical Curie-Weiss behaviour for T > 105 K. A canted AFM state is proposed for

Synthesis and Characterization of Metal Phosphates for Photocatalytic Applications

KAUST Repository

Al-Sabban, Bedour

2012-07-01

Solar energy is the most abundant efficient and important source of renewable energy. The objective of this study is to develop highly efficient visible light responsive photocatalysts for overall water splitting. This is done by using silver or copper containing materials. Phosphate compounds have caught much attention due to their rigid structure, thermal stability and resistance to chemical attacks. Solid phosphates can be prepared by direct solid-state reaction between metal cations and phosphate anions at high temperatures. Double metal phosphates of the Nasion-type structure had shown further technological importance. It has been reported that well-crystallized double metal phosphate particles have excellent ordering and cationic conduction channels in the Nasicon framework. In this study, several Nasion-type structured materials have been synthesized by solid-state method (e.g. CuTi2(PO4)3 and AgTi2(PO4)3) heated up under different temperatures (400–1100C) in N2 or air atmosphere. These materials were characterized by XRD, SEM, DR-UV-Vis spectroscopy and tested for photocatalytic applications. A new method for direct synthesis of photoelectrode on Ti Plate had been demonstrated. Further investigations on controlling the size and morphology for better performance of single and double metal phosphates will be done.

Development of inhibitors of the 2C-methyl-D-erythritol 4-phosphate (MEP) pathway enzymes as potential anti-infective agents

NARCIS (Netherlands)

Masini, Tiziana; Hirsch, Anna K H

2014-01-01

Important pathogens such as Mycobacterium tuberculosis and Plasmodium falciparum, the causative agents of tuberculosis and malaria, respectively, and plants, utilize the 2C-methyl-D-erythritol 4-phosphate (MEP, 5) pathway for the biosynthesis of isopentenyl diphosphate (1) and dimethylallyl

A new crystal modification of diammonium hydrogen phosphate, (NH42(HPO4

Directory of Open Access Journals (Sweden)

Bernhard Spingler

2010-04-01

Full Text Available The addition of hexafluoridophosphate salts (ammonium, silver, thallium or potassium is usually used to precipitate complex cations from aqueous solutions. It has long been known that PF6− is sensitive towards hydrolysis under acidic conditions [Gebala & Jones (1969. J. Inorg. Nucl. Chem. 31, 771–776; Plakhotnyk et al. (2005. J. Fluorine Chem. 126, 27–31]. During the course of our investigation into coinage metal complexes of diphosphine ligands, we used ammonium hexafluoridophosphate in order to crystallize [Ag(diphosphine2]PF6 complexes. From these solutions we always obtained needle-like crystals which turned out to be the title compound, 2NH4+·HPO42−. It was received as the hydrolysis product of NH4PF6. The crystals are a new modification of diammonium hydrogen phosphate. In contrast to the previously published polymorph [Khan et al. (1972. Acta Cryst. B28, 2065–2069], Z′ of the title compound is 2. In the new modification of the title compound, there are eight molecules of (NH42(HPO4 in the unit cell. The structure consists of PO3OH and NH4 tetrahedra, held together by O—H...O and N—H...O hydrogen bonds.

The structural response of gadolinium phosphate to pressure

Energy Technology Data Exchange (ETDEWEB)

Heffernan, Karina M. [Department of Geosciences, Virginia Tech, Blacksburg, VA 24061 (United States); Ross, Nancy L., E-mail: nross@vt.edu [Department of Geosciences, Virginia Tech, Blacksburg, VA 24061 (United States); Spencer, Elinor C. [Department of Geosciences, Virginia Tech, Blacksburg, VA 24061 (United States); Boatner, Lynn A. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

2016-09-15

Accurate elastic constants for gadolinium phosphate (GdPO{sub 4}) have been measured by single-crystal high-pressure diffraction methods. The bulk modulus of GdPO{sub 4} determined under hydrostatic conditions, 128.1(8) GPa (K′=5.8(2)), is markedly different from that obtained with GdPO{sub 4} under non-hydrostatic conditions (160(2) GPa), which indicates the importance of shear stresses on the elastic response of this phosphate. High pressure Raman and diffraction analysis indicate that the PO{sub 4} tetrahedra behave as rigid units in response to pressure and that contraction of the GdPO{sub 4} structure is facilitated by bending/twisting of the Gd–O–P links that result in increased distortion in the GdO{sub 9} polyhedra. - Graphical abstract: A high-pressure single crystal diffraction study of GdPO{sub 4} with the monazite structure is presented. The elastic behaviour of rare-earth phosphates are believed to be sensitive to shear forces. The bulk modulus of GdPO{sub 4} measured under hydrostatic conditions is 128.1(8) GPa. Compression of the structure is facilitated by bending/twisting of the Gd−O−P links that result in increased distortion in the GdO{sub 9} polyhedra. Display Omitted - Highlights: • The elastic responses of rare-earth phosphates are sensitive to shear forces. • The bulk modulus of GdPO{sub 4} measured under hydrostatic conditions is 128.1(8) GPa. • Twisting of the inter-polyhedral links allows compression of the GdPO{sub 4} structure. • Changes to the GdO{sub 9} polyhedra occur in response to pressure (<7.0 GPa).

On the mechanism of ion exchange in zirconium phosphates

International Nuclear Information System (INIS)

Clearfield, A.; Frianeza, T.N.

1978-01-01

α-titanium phosphate, Ti(HPO 4 ) 2 .H 2 O, was found to form two sodium ion exchanged phases. A half exchanged phase of ideal composition TiNaH(PO 4 ) 2 .4H 2 O formed first. However, before all of the titanium phosphate was converted to this phase a second phase of higher Na + content formed. Thus, a three phase solid existed until sufficient sodium ion uptake (approximately 5.5 meq/g) produced only the two exchanged phases. Finally, the half exchanged phase was converted to the more highly loaded one and this latter phase existed from 6 to 8 meq/g of Na + uptake. Severe disordering of the crystal lattice during exchange is proposed to explain this unusual exchange behavior. A broad range of titanium phosphate-zirconium phosphate solid solutions was found to form. Their behavior towards Na + -H + exchange was determined and interpreted on the basis of the known behavior of the pure phases. Mixed Ti-Zr solid solutions of their pyrophosphates were obtained at elevated temperatures. (author)

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

Science.gov (United States)

Gouider, Mbarka; Feki, Mongi; Sayadi, Sami

2009-10-30

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

Phosphorus release from phosphate rock and iron phosphate by low-molecular-weight organic acids.

Science.gov (United States)

Xu, Ren-kou; Zhu, Yong-guan; Chittleborough, David

2004-01-01

Low-molecular-weight(LMW) organic acids widely exist in soils, particularly in the rhizosphere. A series of batch experiments were carried out to investigate the phosphorus release from rock phosphate and iron phosphate by low-molecular-weight organic acids. Results showed that citric acid had the highest capacity to solubilize P from both rock and iron phosphate. P solubilization from rock phosphate and iron phosphate resulted in net proton consumption. P release from rock phosphate was positively correlated with the pKa values. P release from iron phosphate was positively correlated with Fe-organic acid stability constants except for aromatic acids, but was notcorrelated with pKa. Increase in the concentrations of organic acids enhanced P solubilization from both rock and iron phosphate almost linearly. Addition of phenolic compounds further increased the P release from iron phosphate. Initial solution pH had much more substantial effect on P release from rock phosphate than from iron phosphate.

Water in Pyroxene and Olivine from Martian Meteorites

Science.gov (United States)

Peslier, A. H.

2012-01-01

Water in the interior of terrestrial planets can be dissolved in fluids or melts and hydrous phases, but can also be locked as protons attached to structural oxygen in lattice defects in nominally anhydrous minerals (NAM) like olivine, pyroxene, or feldspar [1-3]. Although these minerals contain only tens to hundreds of ppm H2O, this water can amount to at least one ocean in mass when added at planetary scales because of the modal dominance of NAM in the mantle and crust [4]. Moreover these trace amounts of water can have drastic effects on melting temperature, rheology, electrical and heat conductivity, and seismic wave attenuation [5]. There is presently a debate on how much water is present in the martian mantle. Secondary ionization mass spectrometry (SIMS) studies of NAM [6], amphiboles and glass in melt inclusions [7-10], and apatites [11, 12] from Martian meteorites report finding as much water as in the same phases from Earth's igneous rocks. Most martian hydrous minerals, however, generally have the relevant sites filled with Cl and F instead of H [13, 14], and experiments using Cl [15] in parent melts can reproduce Martian basalt compositions as well as those with water [16]. We are in the process of analyzing Martian meteorite minerals by Fourier transform infrared spectrometry (FTIR) in order to constrain the role of water in this planet s formation and magmatic evolution

Preparation and bioactivity of micro-arc oxidized calcium phosphate coatings

Energy Technology Data Exchange (ETDEWEB)

Pan, Y.K. [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Ji' nan, Shandong 250061 (China); School of Materials Science and Engineering, Shandong University, Ji' nan, Shandong 250061 (China); Chen, C.Z., E-mail: czchen@sdu.edu.cn [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Ji' nan, Shandong 250061 (China); School of Materials Science and Engineering, Shandong University, Ji' nan, Shandong 250061 (China); Wang, D.G.; Lin, Z.Q. [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Ji' nan, Shandong 250061 (China); School of Materials Science and Engineering, Shandong University, Ji' nan, Shandong 250061 (China)

2013-09-16

Calcium phosphate (CaP) coatings were prepared on ZK60 magnesium alloy by micro-arc oxidation (MAO) in electrolyte containing calcium acetate monohydrate (CH{sub 3}COO){sub 2}Ca·H{sub 2}O) and disodium hydrogen phosphate dodecahydrate (Na{sub 2}HPO{sub 4}·12H{sub 2}O). Scanning electron microscope (SEM), energy-dispersive X-ray spectrometry (EDX) and X-ray diffractometer (XRD) were employed to characterize the microstructure, elemental distribution and phase composition of the CaP coatings respectively. Simulated body fluid (SBF) immersion test was used to evaluate the coating degradability and bioactivity. After 30 days of SBF immersion, the CaP coatings effectively reduce the degradation rate. The surfaces of CaP coatings are covered by a new layer formed of numerous needle-like, spherical and columned calcium phosphates. SEM, EDX and XRD results suggest that these calcium phosphates are bioactive calcium phosphate phases such as hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}, HA) and calcium pyrophosphates (Ca{sub 2}P{sub 2}O{sub 7}, CPP). The formation of these calcium phosphates indicates that the CaP coatings have bioactivity. - Highlights: • Bioactive CaP coatings are successfully formed on ZK60 magnesium alloy. • CaP coatings consist of MgO, MgF{sub 2}, CaO, CaF{sub 2} and Ca{sub 3}(PO{sub 4}){sub 2}. • Needle-like, spherical and columned calcium phosphates formed in SBF. • CaP coatings exhibit bioactivity and low corrosion rate.

Interaction between calcium and phosphate adsorption on goethite.

Science.gov (United States)

Rietra, R P; Hiemstra, T; van Riemsdijk, W H

2001-08-15

Quantitatively, little is known about the ion interaction processes that are responsible for the binding of phosphate in soil, water, and sediment, which determine the bioavailability and mobility of phosphate. Studies have shown that metal hydroxides are often responsible for the binding of PO4 in soils and sediments, but the binding behavior of PO4 in these systems often differs significantly from adsorption studies on metal hydroxides in laboratory. The interaction between PO4 and Ca adsorption was studied on goethite because Ca can influence the PO4 adsorption equilibria. Since adsorption interactions are very difficult to discriminate from precipitation reactions, conditions were chosen to prevent precipitation of Ca-PO4 solids. Adsorption experiments of PO4 and Ca, individually and in combination, show a strong interaction between adsorbed Ca and PO4 on goethite for conditions below the saturation index of apatite. It is shown that it is possible to predict the adsorption and interaction of PO4 and Ca on electrostatic arguments using the model parameter values derived from the single-ion systems and without invoking ternary complex formation or precipitation. The model enables the prediction of the Ca-PO4 interaction for environmentally relevant calcium and phosphate concentrations.

Crystal structure and Mössbauer spectroscopy of a new iron phosphate Mg{sub 2.88}Fe{sub 4.12}(PO{sub 4}){sub 6}

Energy Technology Data Exchange (ETDEWEB)

Saad, Y. [UR Matériaux Inorganiques, Faculté des Sciences, 5019 Monastir (Tunisia); Hidouri, M., E-mail: mourad_hidouri@yahoo.fr [UR Matériaux Inorganiques, Faculté des Sciences, 5019 Monastir (Tunisia); Álvarez-Serrano, I.; Veiga, M.L. [Departamento de Química Inorgánica I, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid (Spain); Wattiaux, A. [Institut de Chimie de la Matière Condensée de Bordeaux, CNRS, Université de Bordeaux I, 87 Avenue du Dr. A. Schweitzer, 33608 Pessac-Cedex (France); Amara, Mongi B. [UR Matériaux Inorganiques, Faculté des Sciences, 5019 Monastir (Tunisia)

2014-01-25

Highlights: • This study reports the synthesis and characterization of a new iron phosphate. • The cationic distribution is supported by a Mössbauer spectroscopy study. • The magnetic susceptibility results are discussed. -- Abstract: A new mixed valence iron phosphate Mg{sub 2.88}Fe{sub 4.12}(PO{sub 4}){sub 6} has been prepared as single crystals by the flux method and as a powder by solid state reaction and its crystal structure has been determined by X-ray diffraction. This compound crystallises in the triclinic system with space group P1{sup ¯} and a = 6.325(5) Å, b = 7.911(3) Å, c = 9.271(3) Å, α = 104.62(1)°, β = 108.41(1)° and γ = 101.24(1)° and Z = 1. Its structure is similar to that of the mineral howardevansite. It consists of Fe{sub 2}O{sub 10} bioctahedral units and MgO{sub 5} trigonal bipyramids sharing edges to form infinite zigzag chains. Such chains are linked to each other by MO{sub 6} (0.88 Mg{sup 2+} + 0.12 Fe{sup 2+}) octahedra and PO{sub 4} tetrahedra resulting in a 3D covalent framework. Magnetic measurements indicated two successive transitions at 46 K and 22 K. Mössbauer spectroscopy confirmed the mixed valence of iron and gave accurate information about its local environment.

Removal mechanism of phosphate from aqueous solution by fly ash.

Science.gov (United States)

Lu, S G; Bai, S Q; Zhu, L; Shan, H D

2009-01-15

This work studied the effectiveness of fly ash in removing phosphate from aqueous solution and its related removal mechanism. The adsorption and precipitation of phosphate by fly ash were investigated separately in order to evaluate their role in the removal of phosphate. Results showed that the removal of phosphate by fly ash was rapid. The removal percentage of phosphate in the first 5min reached 68-96% of the maximum removal of phosphate by fly ash. The removal processes of phosphate by fly ash included a fast and large removal representing precipitation, then a slower and longer removal due to adsorption. The adsorption of phosphate on fly ash could be described well by Freundlich isotherm equation. The pH and Ca2+ concentration of fly ash suspension were decreased with the addition of phosphate, which suggests that calcium phosphate precipitation is a major mechanism of the phosphate removal. Comparison of the relative contribution of the adsorption and precipitation to the total removal of phosphate by fly ash showed that the adsorption accounted for 30-34% of the total removal of phosphate, depending on the content of CaO in fly ash. XRD patterns of the fly ash before and after phosphate adsorption revealed that phosphate salt (CaHPO4 x 2H2O) was formed in the adsorption process. Therefore, the removal of phosphate by fly ash can be attributed to the formation of phosphate precipitation as a brushite and the adsorption on hydroxylated oxides. The results suggested that the use of fly ash could be a promising solution to the removal of phosphate in the wastewater treatment and pollution control.

Inhibition of calcium phosphate precipitation under environmentally-relevant conditions

International Nuclear Information System (INIS)

Cao Xinde; Harris, Willie G.; Josan, Manohardeep S.; Nair, Vimala D.

2007-01-01

Precipitation of Ca phosphates plays an important role in controlling P activity and availability in environmental systems. The purpose of this study was to determine inhibitory effects on Ca phosphate precipitation by Mg 2+ , SO 4 2- , CO 3 2- , humic acid, oxalic acid, biogenic Si, and Si-rich soil clay commonly found in soils, sediments, and waste streams. Precipitation rates were determined by measuring decrease of P concentration in solutions during the first 60 min; and precipitated solid phases identified using X-ray diffraction and electron microscopy. Poorly-crystalline hydroxyapatite (HAP: Ca 5 (PO 4 ) 3 OH) formed in control solutions over the experiment period of 24 h, following a second-order dependence on P concentration. Humic acid and Mg 2+ significantly inhibited formation of HAP, allowing formation of a more soluble amorphous Ca phosphate phase (ACP), and thus reducing the precipitation rate constants by 94-96%. Inhibition caused by Mg 2+ results from its incorporation into Ca phosphate precipitates, preventing formation of a well-crystalline phase. Humic acid likely suppressed Ca phosphate precipitation by adsorbing onto the newly-formed nuclei. Presence of oxalic acid resulted in almost complete inhibition of HAP precipitation due to preemptive Ca-oxalate formation. Carbonate substituted for phosphate, decreasing the crystallinity of HAP and thus reducing precipitation rate constant by 44%. Sulfate and Si-rich solids had less impact on formation of HAP; while they reduced precipitation in the early stage, they did not differ from the control after 24 h. Results indicate that components (e.g., Mg 2+ , humic acid) producing relatively soluble ACP are more likely to reduce P stability and precipitation rate of Ca phosphate in soils and sediments than are components (e.g., SO 4 2- , Si) that have less effect on the crystallinity

Water-rock interaction in a high-FeO olivine rock in nature

International Nuclear Information System (INIS)

Hellmuth, K.H.; Lindberg, A.; Tullborg, E.L.

1992-12-01

The long-term behaviour in nature of high-FeO olivine rock in contact with surface water has been studied at the Lovasjaervi instrusion, SE-Finland. The rock has been proposed as a high-capasity, higly reactive redox-buffer backfill in a repository for spent fuel. Favourable groundwater chemistry is a major parameter relevant to safety of such a repository. Reducing conditions favour the retardation of long-lived, redox-sensitive radionuclides. Weathering influences have been studied at the natural outcrop of the rock mass. The interaction of oxidizing surface waters with rock at greater depths has been studied by using fissure filling minerals. Investigation of weathered rock from the outcrop indicates that the olivine rock is highly reactive on a geological time scale and its redox capasity is available although the instrusion as a whole is surprisingly well preserved. The fissure fillings studied allow the conclusion that oxygen seems to be efficiently removed from intruding surface water. Oxidation seem to have caused visible effects only along very conducting fractures and near the contact zones of the surrounding granitic rock. Stable isotope data of fissure filling calcites indicate that the influence of surface waters can be traced clearly down to a depth of about 50 m, but also at greater depths re-equilibration has occurred. Groundwater data from the site were not available. (orig.)

Environmental monitoring at the Seqi olivine mine 2010

DEFF Research Database (Denmark)

Søndergaard, Jens; Asmund, Gert

monitoring studies conducted in 2010. Results from previous years have shown that operation of the mine caused levels of some elements, particularly chromium and nickel, to increase in lichens, blue mussels and seaweed within the surrounding area compared to pre-mining conditions. The main source......The olivine mine at Seqi in West Greenland operated between 2005 and 2010. Since 2004, environmental monitoring studies have been conducted at Seqi every year in order to assess premining conditions and subsequently the impact from mining during operation. This report contains the results from...... of contamination is considered the generation and spreading of metal-contaminated dust from the roads and the ore-crushing facility. Results from 2010 show that levels of chromium and nickel in lichens are still elevated but that dust deposition rates have decreased from 2008 to 2010. Similarly, levels of chromium...

Bulk solubility and speciation of plutonium(VI) in phosphate-containing solutions

International Nuclear Information System (INIS)

Weger, H.T.; Okajima, S.; Cunnane, J.C.; Reed, D.T.

1992-01-01

The solubility and speciation of Pu(VI) with phosphate as a function of pH was investigated to determine the ability of phosphate to act as an actinide getter. The general properties were first investigated and are reported here with the goal of performing more quantitative experiments in the future. Solubility was approached from oversaturation at initial pH = 4, 10 and 13.4. Absorption spectra were recorded, the solution filtered and the filtrate counted. Absorption spectra were obtained at varying phosphate concentrations and at pH of 2.7 to 11.9. The effect of complexation on the 833 mn Pu(VI) band was characterized. Evidence for three phosphate complexes was obtained for pH -5 to 10 -6 M Pu(VI) was measured in the filtrate at pH ≤ 10 that were passed through a 50 mn filter. Pu(VI) complexes with phosphate over hydroxide at pH ≤ 11.6, but at pH ≥ 11.9, only hydrolyzed Pu(VI) was detected. At pH = 12, the concentration of Pu(VI) was as high as 10 -4 M

Hydrothermal synthesis and characterization of a new three-dimensional hybrid zinc phosphate [Zn2(HPO4)2(4,4'-bipy)].3H2O with neutral porous framework

International Nuclear Information System (INIS)

Wang Lei; Yang Ming; Li Guanghua; Shi Zhan; Feng Shouhua

2006-01-01

Employing 4,4'-bipyridine as a bridged ligand, a new three-dimensional (3-D) hybrid zinc phosphate [Zn 2 (HPO 4 ) 2 (4,4'-bipy)].3H 2 O has been prepared under hydrothermal conditions and characterized by single crystal X-ray diffraction. This compound crystallizes in the monoclinic space group C2/c, with cell parameters, a=21.188(4)A, b=10.229(2)A, c=9.0656(18)A, β=90.21(3) o , V=1964.8(7)A 3 and Z=4. The connectivity of the ZnO 3 N and HPO 4 tetrahedra results in a 2-D neutral layer that with interesting 4,8 2 net along the bc plane. Furthermore, the 4,4'-bipyridine molecule links the 4,8 2 net into a 3-D structure. The water molecules sit in the middle of the channels and interact with the framework via hydrogen bonds. The compound exhibits intense photoluminescence at room temperature

Electrochemical potentials of layered oxide and olivine phosphate ...

Indian Academy of Sciences (India)

Lithium ion battery; cathodes; density functional theory; density of states; Bader charge analysis; electrochemical ... voltage, ionic diffusion coefficient, phase stability and charge ... routes to synthesis and fabrication techniques. .... from the lithiated one. ..... Ebner W, Fouchard D and Xie L 1994 Solid State Ionics 69 238.

Luminescence and excited state dynamics in Bi{sup 3+}-doped LiLaP{sub 4}O{sub 12} phosphates

Energy Technology Data Exchange (ETDEWEB)

Babin, V. [Institute of Physics AS CR, Cukrovarnicka 10, 16200 Prague (Czech Republic); Chernenko, K., E-mail: nuclearphys@yandex.ru [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Peter the Great Saint-Petersburg Polytechnic University, Polytekhnicheskaya 29, 195251 St.Petersburg (Russian Federation); Demchenko, P. [Ivan Franko National University of Lviv, Kyryla i Mefodiya 8a, 79005 Lviv (Ukraine); Mihokova, E.; Nikl, M. [Institute of Physics AS CR, Cukrovarnicka 10, 16200 Prague (Czech Republic); Pashuk, I. [Ivan Franko National University of Lviv, Kyryla i Mefodiya 8a, 79005 Lviv (Ukraine); Shalapska, T. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Voloshinovskii, A. [Ivan Franko National University of Lviv, Kyryla i Mefodiya 8a, 79005 Lviv (Ukraine); Zazubovich, S. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia)

2016-08-15

Photo- and X-ray-excited luminescence characteristics of Bi-doped LiLaP{sub 4}O{sub 12} phosphates with different bismuth contents (from 1 to 25 at% in the melt) are investigated in the 4.2–300 K temperature range and compared with the characteristics of the undoped LiLaP{sub 4}O{sub 12} phosphate. The broad 2.95 eV emission band of LiLaP{sub 4}O{sub 12}:Bi excited around 5.4 eV is found to arise from the bismuth dopant. Relatively large FWHM and Stokes shift of the emission band and especially the data on the low-temperature decay kinetics of the 2.95 eV emission and its temperature dependence, indicating a very small spin-orbit splitting energy of the corresponding excited state, allow the conclusion that this emission arises from the radiative decay of the triplet state of an exciton localized around a Bi{sup 3+} ion. No spectral bands are observed, arising from the electron transitions between the energy levels of Bi{sup 3+} ions. Phenomenological model is proposed for the description of the excited state dynamics of the Bi{sup 3+}-related localized exciton in LiLaP{sub 4}O{sub 12}:Bi and the parameters of the triplet localized exciton state are determined. Keywords: Photoluminescence; Time-resolved spectroscopy; Excited states; Bi{sup 3+} centers; LiLaP{sub 4}O{sub 12}:Bi powders.

Quantitative Mechanistic Description of Natural Radionuclide and Iron Sorption on phosphate Fertilizer Materials

International Nuclear Information System (INIS)

Kamel, N.H.M.

2008-01-01

The mean activity values of the radionuclide 226 Ra, 238 U and 232 Th decay series, and the radioactive isotopes of 40 K in Bq/kg dry weight of the phosphate ore (Pho-ore), single super phosphate granules, (SSP-G), single super phosphate powder (SSP-P), triple super phosphate (TSP), and phosphogypsum (CaSO 4 ) samples were determined. CaSO 4 sample was found to contain, 300 Bq/kg of radioactive 238 U which is less than the values found in other studied phosphate samples. CaSO 4 sample was found to contain the highest amount of 226 Ra concentration value of 850 Bq/kg. Phosphate fertilizer components are acidic character, therefore, the solid surfaces will in general acquire a surface electric charge when contact with polar solvent such as water. The net electric charge obtained through uptake or release of potential determining ions (e.g, H + or OH - ). Thus the solid surfaces tend to adsorb and/or release of different ions to maintain neutral. The aim of this study is to determine the electric charge and the surface electric potential at the phosphate fertilizer materials

Transient shallow reservoirs beneath small eruptive centres: Constraints from Mg-Fe interdiffusion in olivine

Science.gov (United States)

Morgado, E.; Parada, M. A.; Morgan, D. J.; Gutiérrez, F.; Castruccio, A.; Contreras, C.

2017-11-01

Small eruptive centres commonly have more primitive lavas than those associated with stratovolcanoes, an observation that has been taken to indicate a short magma residence in the crust relative to those reservoirs below stratovolcanoes. The Caburgua cones of the Andean Southern Volcanic Zone from a basaltic small eruptive centre where this can be tested. Here, we use MELTS simulations, and the available thermobarometry data to determine the conditions of olivine crystal rim formation and the Mg-Fe diffusion modelling to determine the magma residence times of those rims in the crust. Results yield timescales varying from a few days to dozens of days, and if freezing is to be avoided, can only be explained by some form of storage or slow transport through at least one shallow magma body. The longest durations of magma residence seen in the olivine rim zones are up to 471 days. These timescales are shorter than those estimated (decadal) from the nearby, more-differentiated, and well-established stratovolcano, Villarrica, which has a dominantly basaltic andesite composition. For Caburgua cones, we propose the existence of a transient reservoir, in contrast to a long-lived reservoir such as that inferred beneath the adjacent Villarrica stratovolcano.

Water sensitivity of the seismic properties of upper-mantle olivine

Science.gov (United States)

Cline, Christopher; David, Emmanuel; Faul, Ulrich; Berry, Andrew; Jackson, Ian

2017-04-01

The wave speeds and attenuation of seismic waves in the upper mantle are expected to be strongly influenced by the defect chemistry of olivine grain interiors and the associated chemical complexity of grain-boundary regions. Changes in chemical environment (oxygen fugacity and/or water fugacity) can impose different defect chemistries, including the creation and retention of hydrous defects, and therefore can directly influence anelastic relaxation involving stress-induced migration of lattice defects and/or grain-boundary sliding. Here we report the first low-frequency experimental study of the seismic properties of olivine under water-undersaturated conditions. Three synthetic sol-gel derived olivine (Fo90) specimens were fabricated by hot-pressing in welded Pt capsules with various concentrations of hydroxyl, chemically bound as doubly protonated Si vacancies, charge balanced by substitution of Ti on a neighboring M-site (i.e., the Ti-clinohumite-like defect). Hydroxyl contents, determined following the subsequent mechanical testing within Pt sleeves, increased systematically with the amount of added Ti-dopant. Added Ti concentrations ranged between 176 and 802 atom ppm Ti/Si, resulting in concentrations of bound hydrogen in the three samples ranging between 330 and 1150 atom ppm H/Si. Each hot-pressed specimen was precision ground and then sleeved in Pt for mechanical testing in forced torsional oscillation under water-undersaturated conditions. Forced-oscillation tests were conducted at seismic periods of 1 - 1000 s and 200 MPa confining pressure during slow staged cooling from 1200 to 25°C. Each Ti-doped specimen showed mechanical behavior of the high-temperature background type involving monotonically increasing dissipation and decreasing shear modulus with increasing oscillation period and increasing temperature. Comparison of the mechanical data acquired in these water-undersaturated conditions with a similarly tested, but dry, Ti-bearing specimen

Spectroscopic properties of highly Nd-doped lead phosphate glass

Energy Technology Data Exchange (ETDEWEB)

Novais, A.L.F. [Instituto de Física, Universidade Federal de Alagoas, Grupo de Fotônica e Fluidos Complexos, 57072-970 Maceió, AL (Brazil); Dantas, N.O. [Laboratório de Novos Materiais Isolantes e Semicondutores (LNMIS), Instituto de Física, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Guedes, I. [Departamento de Física, Universidade Federal do Ceará, Campus do PICI, Caixa Postal 6030, 60455-760 Fortaleza, CE (Brazil); Vermelho, M.V.D., E-mail: vermelho@fis.ufal.br [Instituto de Física, Universidade Federal de Alagoas, Grupo de Fotônica e Fluidos Complexos, 57072-970 Maceió, AL (Brazil)

2015-11-05

The spectroscopic characteristics of highly Nd{sup 3+}-doped lead phosphate glasses (xNd:Pb{sub 3}(PO{sub 4}){sub 2}) have been investigated. The X-ray spectra show that the matrices are glassy up to 25 wt% of Nd{sup 3+} doping. From the Judd–Ofelt analysis we observe that while the Ω{sub (2)} parameter remains constant indicating that the 4f{sup N} and 4f{sup N−1}5 d{sup 1} configurations are not affected by the Nd{sup 3+} doping, the behavior of both Ω{sub (4)} and Ω{sub (6)} changes for 15 wt% of Nd{sup 3+} doping. The reduction of the Ω{sub (6)} parameter is related to the increase of the covalence bonding between the ligands and the Nd{sup 3+} ions. At this particular concentration, the radiative lifetime has a four-fold enhancement. Such behaviors are likely to be related to a modification in the glass structure for high Nd{sup 3+} concentrations. - Graphical abstract: Highly doped lead-phosphate glass matrix, with nominal concentration of up to 25 wt%, maintain the spectroscopic properties without deterioration. The analysis concerning the point of view of Nd{sup 3+} ions showed that high concentrations only affects the rare earth electronic charge density distribution. - Highlights: • Spectroscopic characterization of Nd{sub 2}O{sub 3} highly doped lead phosphate glasses. • Phosphate glass doped with Nd{sup 3+} for applications in photonic devices. • Judd–Ofelt analysis in phosphate glasses doped with Neodymium.

Products and stability of phosphate reactions with lead under freeze-thaw cycling in simple systems

International Nuclear Information System (INIS)

Hafsteinsdottir, Erla G.; White, Duanne A.; Gore, Damian B.; Stark, Scott C.

2011-01-01

Orthophosphate fixation of metal contaminated soils in environments that undergo freeze-thaw cycles is understudied. Freeze-thaw cycling potentially influences the reaction rate, mineral chemical stability and physical breakdown of particles during fixation. This study determines what products form when phosphate (triple superphosphate [Ca(H 2 PO 4 ) 2 ] or sodium phosphate [Na 3 PO 4 ]) reacts with lead (PbSO 4 or PbCl 2 ) in simple chemical systems in vitro, and assesses potential changes in formation during freeze-thaw cycles. Systems were subjected to multiple freeze-thaw cycles from +10 deg. C to -20 deg. C and then analysed by X-ray diffractometry. Pyromorphite formed in all systems and was stable over multiple freeze-thaw cycles. Low temperature lead orthophosphate reaction efficiency varied according to both phosphate and lead source; the most time-efficient pyromorphite formation was observed when PbSO 4 and Na 3 PO 4 were present together. These findings have implications for the manner in which metal contaminated materials in freezing ground can be treated with phosphate. - Highlights: → Formation of lead phosphate products in cold environments is identified. → Potential change in formation during freeze-thaw cycling is assessed. → Lead phosphate reaction efficiency varies according to phosphate and lead source. → Pyromorphite formation is stable during 240 freeze-thaw cycles. - Pyromorphite, formed from Pb phosphate fixation, is stable during multiple freeze-thaw cycles but the efficiency of the fixation depends on the phosphate source and the type of Pb mineral.

A Novel Framework Antimony (III) Phosphate: Synthesis and Structure of NaSb 3O 2(PO 4) 2

Science.gov (United States)

Adair, Brian A.; de Delgado, Graciela Díaz; Miguel Delgado, J.; Cheetham, Anthony K.

2000-04-01

The antimony (III) phosphate, NaSb3O2(PO4)2, is a framework structure built from SbIII and PV centers; orthorhombic, space group Pca21 (No. 29), a=13.944(3), b=6.6822(13), c=20.886(4) Å, V=1946.1(7) Å3, Z=8. Stereochemically active lone pairs of electrons associated with SbIIIO5 and SbIIIO4 polyhedra point into eight-ring channels, approximately 5×7 Å2, which dominate the architecture of the title compound. Charge-compensating sodium cations occupy the remaining space in the channels.

Phosphate Recovery From Sewage Sludge Containing Iron Phosphate

NARCIS (Netherlands)

Wilfert, P.K.

2018-01-01

The scope of this thesis was to lay the basis for a phosphate recovery technology that can be applied on sewage sludge containing iron phosphate. Such a technology should come with minimal changes to the existing sludge treatment configuration while keeping the use of chemicals or energy as small as

Influence of octacalcium phosphate coating on osteoinductive properties of biomaterials

NARCIS (Netherlands)

Habibovic, Pamela; van der Valk, C.M.; van Blitterswijk, Clemens; de Groot, K.

2004-01-01

In this study, we investigated the influence of octacalcium phosphate (OCP) coating on osteoinductive behaviour of the biomaterials. Porous titanium alloy (Ti6Al4V), hydroxyapatite (HA), biphasic calcium phosphate (BCP) and polyethylene glyco terephtalate/polybuthylene terephtalate (PEGT–PBT)

Ion exchange and electrochemical evaluation of the microporous phosphate Li9Fe7(PO4)10

International Nuclear Information System (INIS)

Becht, Gregory A.; Vaughey, John T.; Britt, Robin L.; Eagle, Cassandra T.; Hwu, Shiou-Jyh

2008-01-01

A new lithium iron(III) phosphate, Li 9 Fe 7 (PO 4 ) 10 , has been synthesized and is currently under electrochemical evaluation as an anode material for rechargeable lithium-ion battery applications. The sample was prepared via the ion exchange reaction of Cs 5 K 4 Fe 7 (PO 4 ) 10 1 in the 1 M LiNO 3 solution under hydrothermal conditions at 200 deg. C. The fully Li + -exchanged sample Li 9 Fe 7 (PO 4 ) 10 2 cannot yet be synthesized by conventional high-temperature, solid-state methods. The parent compound 1 is a member of the Cs 9-x K x Fe 7 (PO 4 ) 10 series that was previously isolated from a high-temperature (750 deg. C) reaction employing the eutectic CsCl/KCl molten salt. The polycrystalline solid 1 was first prepared in a stoichiometric reaction via conventional solid-state method then followed by ion exchange giving rise to 2. Both compounds adopt three-dimensional structures that consist of orthogonally interconnected channels where electropositive ions reside. It has been demonstrated that the Cs 9-x K x Fe 7 (PO 4 ) 10 series possesses versatile ion exchange capabilities with all the monovalent alkali metal and silver cations due to its facile pathways for ion transport. 1 and 2 were subject to electrochemical analysis and preliminary results suggest that the latter can be considered as an anode material. Electrochemical results indicate that Li 9 Fe 7 (PO 4 ) 10 is reduced below 1 V (vs. Li) to most likely form a Fe(0)/Li 3 PO 4 composite material, which can subsequently be cycled reversibly at relatively low potential. An initial capacity of 250 mAh/g was measured, which is equivalent to the insertion of thirteen Li atoms per Li 9+x Fe 7 (PO 4 ) 10 (x = 13) during the charge/discharge process (Fe 2+ + 2e → Fe 0 ). Furthermore, 2 shows a lower reduction potential (0.9 V), by approximately 200 mV, and much better electrochemical reversibility than iron(III) phosphate, FePO 4 , highlighting the value of improving the ionic conductivity of the sample

Phosphate, urea and creatinine clearances: haemodialysis adequacy assessed by weekly monitoring.

Science.gov (United States)

Debowska, Malgorzata; Wojcik-Zaluska, Alicja; Ksiazek, Andrzej; Zaluska, Wojciech; Waniewski, Jacek

2015-01-01

The specific distribution of phosphate and the control mechanisms for its plasma level makes phosphate kinetics during haemodialysis (HD) considerably different from those of urea and creatinine and makes the quantitative evaluation of adequacy of phosphate removal difficult. We propose the application of equivalent continuous clearance (ECC) as a phosphate adequacy parameter and compare it with ECC for creatinine and urea. Three consecutive dialysis sessions were evaluated for 25 patients on maintenance HD. Concentrations of phosphate, urea and creatinine in plasma were measured every 1h during the treatment and 45 min after, and every 30 min in dialysate. ECC was calculated using the removed solute mass assessed in dialysate and weekly solute profile in plasma. Similar calculations were performed also for the midweek dialysis session only. Different versions of the reference concentration for ECC were applied. ECC with peak average reference concentration was 5.4 ± 1.0 for phosphate, 7.0 ± 1.0 for urea and 4.7 ± 1.0 mL/min for creatinine. ECC for urea and creatinine were well correlated in contrast to the correlations of ECC for phosphate versus urea and creatinine. Midweek ECC were higher than weekly ECC, but they were well correlated for urea and creatinine, but only weakly for phosphate. HD adequacy monitoring for phosphate may be performed using ECC, but it is less predictable than similar indices for urea and creatinine. The values of ECC for phosphate are within the range expected for its molecular size compared with those for urea and creatinine. © The Author 2014. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

Preparation and thermogravimetric study of some uranyl phosphates

International Nuclear Information System (INIS)

Schaekers, J.M.

1970-10-01

The preparation of uranyl ammonium phosphate trihydrate (UAP = UO 2 NH 4 PO 4 .3H 2 O), acid uranyl phosphate tetrahydrate(AUP = UO 2 HPO 4 .4H 2 O) and neutral uranyl phosphate tetrahydrate (NUPT = (UO 2 ) 3 (PO 4 ) 2 .4H 2 O) was investigated during the data from the literature. The thermal decomposition in different atmospheres, such as air, oxygen, nitrogen and argon, was studied in the temperature range 25-1000 0 C. It was found that the pyrophosphate U 2 O 3 P 2 O 7 is a stable decomposition product of UAP as well as of AUP. A mixture of U 3 O 8 and U 2 O 3 P 2 O 7 is obtained when the NUPT is decomposed in an oxygen-free atmosphere. NUPT however is stable in an oxidising atmosphere. Hydrogen and carbon reductions were also carried out, and UO 2 or (UO) 2 P 2 O 7 as well as mixtures of these two products can be obtained, depending on the starting material and the reduction temperature. The different reduction and decomposition reactions were studied by means of thermogravimetric analysis, and activation energies were calculated where possible. I.R. spectral analysis was also used to identify various products with the same composition [af

Thermal expansion of NZP-family alkali-metal (Na, K) zirconium phosphates

International Nuclear Information System (INIS)

Orlova, A.I.; Kemenov, D.V.; Pet'kov, V.I.; Samojlov, S.G.; Kazantsev, G.N.

2000-01-01

By means of high-temperature X-ray diffraction one investigated into thermal expansion of alkali-zirconium phosphates crystallizing in NaZr 2 (PO 4 ) 3 structure type within 20-700 deg C temperature range. One synthesized phosphates of A x Zr 2.25-0.25x (PO 4 ) 3 type two series where A-Na (x = 0.5; 1.0; 2.0; 3.0; 4.0; 5.0) and K (x = 1.0; 3.0; 5.0). One calculated for them a and c parameters of the elementary cells and α a and α c linear expansion temperature coefficients. Anisotropy of thermal expansion the maximum one for AZr 2 (PO 4 ) 3 and Na 5 Zr(PO 4 ) 3 phosphates was determined. K 5 Zr(PO 4 ) 3 compound was characterized by the minimum thermal expansion at the near-zero anisotropy of Na 5 Zr(PO 4 ) 3 [ru

Increased serum phosphate concentrations in patients with advanced chronic kidney disease treated with diuretics.

Science.gov (United States)

Caravaca, Francisco; García-Pino, Guadalupe; Martínez-Gallardo, Rocío; Ferreira-Morong, Flavio; Luna, Enrique; Alvarado, Raúl; Ruiz-Donoso, Enrique; Chávez, Edgar

2013-01-01

Serum phosphate concentrations usually show great variability in patients with advanced chronic kidney disease (ACKD) not on dialysis. Diuretics treatment can have an influence over the severity of mineral-bone metabolism alterations related to ACKD, but their effect on serum phosphate levels is less known. This study aims to determine whether diuretics are independently associated with serum phosphate levels, and to investigate the mechanisms by which diuretics may affect phosphate metabolism. 429 Caucasian patients with CKD not on dialysis were included in this cross-sectional study. In addition to conventional serum biochemical measures, the following parameters of renal phosphate excretion were assessed: 24-hours urinary phosphate excretion, tubular maximum phosphate reabsorption (TmP), and fractional excretion of phosphate (FEP). 58% of patients were on treatment with diuretics. Patients on diuretics showed significantly higher mean serum phosphate concentration (4.78 ± 1.23 vs. 4.24 ± 1.04 mg/dl; Pdiuretics. By multivariate linear and logistic regression, significant associations between diuretics and serum phosphate concentrations or hyperphosphataemia remained after adjustment for potential confounding variables. In patients with the highest phosphate load adjusted to kidney function, those treated with diuretics showed significantly lower FEP than those untreated with diuretics. Treatment with diuretics is associated with increased serum phosphate concentrations in patients with ACKD. Diuretics may indirectly interfere with the maximum renal compensatory capacity to excrete phosphate. Diuretics should be considered in the studies linking the relationship between serum phosphate concentrations and cardiovascular alterations in patients with CKD.

Phosphate-a poison for humans?

Science.gov (United States)

Komaba, Hirotaka; Fukagawa, Masafumi

2016-10-01

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

Ferroelectric phase transition in hydrogen-bonded 2-aminopyridine phosphate (NC sub 4 H sub 4 NH sub 2)centre dot H sub 3 PO sub 4

CERN Document Server

Czapla, Z; Waskowska, A

2003-01-01

A new crystal of 2-aminopyridine phosphate (NC sub 4 H sub 4 NH sub 2)centre dot H sub 3 PO sub 4 has been grown and its x-ray structure and physical properties were studied. At room temperature the crystals are monoclinic, space group C2/c. The flat 2-aminopyridine cations are hydrogen bonded to the anionic [PO sub 4 ] groups. The interesting feature of the crystal structure is the three-dimensional network of hydrogen bonds including, among others, two strong, symmetrical O centre dot centre dot centre dot H, H centre dot centre dot centre dot O interactions with disordered proton locations. Symmetrically related PO sub 4 anions linked through these protons form infinite (PO sub 4) subinfinity chains along the crystal a-axis. The anomalies in the temperature dependence of the electric permittivity showed that the crystal undergoes ferroelectric phase transition at T sub c = 103.5 K. The spontaneous polarization takes place along the crystal a-axis, being parallel to the chains of the hydrogen-bonded PO sub ...

Partitioning of water between point defects, dislocations, and grain boundaries in olivine

Science.gov (United States)

Tielke, J. A.; Mecklenburgh, J.; Mariani, E.; Wheeler, J.

2017-12-01

Estimates of the storage capacity of water in the interior of the Earth and other terrestrial planets vary significantly. One interpretation is that water in planetary interiors exists primarily as hydrogen ions, dissociated from liquid water, that are associated with point defects in the crystal structure of nominally anhydrous minerals. However, dislocations and grain boundaries may contribute significantly to the storage capacity of water in planetary interiors, but hydrogen concentrations in dislocations and grain boundaries are difficult to quantify. To measure the water storage capacity of dislocations and grain boundaries, we are analyzing results from high-temperature and high-pressure experiments where deuterium, a stable isotope of hydrogen, was incorporated into olivine, the dominate phase in the upper mantle. Compared to hydrogen, deuterium concentrations can be determined at much higher spatial resolution using secondary-ion mass spectroscopy. The concentration of deuterium in the samples will also be quantified using Fourier transform infrared spectroscopy for comparison to results for hydrogen-bearing olivine. The spatial distribution of regions with different densities of geometrically-necessary dislocations and the locations of grain boundaries will be determined using electron-backscatter diffraction (EBSD) analyses. Correlation of the concentration of deuterium with dislocation densities and grain boundaries will be used to examine the partitioning of water-derived species between the different types of defects. Ultimately, these data will be used to place more realistic bounds on the storage capacity of water in the interior of Earth and of other terrestrial planets.

Consortium inoculum of five thermo-tolerant phosphate solubilizing Actinomycetes for multipurpose biofertilizer preparation.

Science.gov (United States)

Nandimath, Arusha P; Karad, Dilip D; Gupta, Shantikumar G; Kharat, Arun S

2017-10-01

Alkaline pH of the soil facilitates the conversion of phosphate present in phosphate fertilizer applied in the field to insoluble phosphate which is not available to plants. Problem of soluble phosphate deficiency arises, primarily due to needless use of phosphate fertilizer. We sought to biofertilizer with the thermo-tolerant phosphate solubilizing actinomycetes consortium that could convert insoluble phosphate to soluble phosphate at wider temperature range. In the present investigation consortium of five thermo-tolerant phosphate solubilizing actinomycetes was applied for preparation of inoculum to produce multipurpose bio-fertilizer. Phosphates solubilizing thermo-tolerant 32 actinomycetes strains were processed for identification with the use of PIBWIN software and were screened for phosphate solubilizing activity. Amongst these five actinomycetes were selected on the basis of their ability to produce cellulase, chitinase, pectinase, protease, lipase, amylase and phosphate solubilizing enzymes. Ability to produce these enzymes at 28°C and 50°C were examined. Biofertilizer was prepared by using agricultural waste as a raw material. While preparation of bio-fertilizer the pH decreased from 7.5 to 4.3 and temperature increased up to 74°C maximum at the end of 4 th week and in subsequent week it started to decline gradually till it reached around 50°C, which was found to be stable up to eighth week. This thermo-tolerant actinomycetes consortium released soluble phosphate of up to 46.7 μg ml -1 . As the mesophilic organisms die out at high temperature of composting hence thormo-tolerant actinomycetes would be the better substitute for preparation of phosphate solubilizing bio-fertilizer with added potential to degrade complex macromolecules in composting.

SLC37A1 and SLC37A2 are phosphate-linked, glucose-6-phosphate antiporters.

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Chi-Jiunn Pan

Full Text Available Blood glucose homeostasis between meals depends upon production of glucose within the endoplasmic reticulum (ER of the liver and kidney by hydrolysis of glucose-6-phosphate (G6P into glucose and phosphate (P(i. This reaction depends on coupling the G6P transporter (G6PT with glucose-6-phosphatase-α (G6Pase-α. Only one G6PT, also known as SLC37A4, has been characterized, and it acts as a P(i-linked G6P antiporter. The other three SLC37 family members, predicted to be sugar-phosphate:P(i exchangers, have not been characterized functionally. Using reconstituted proteoliposomes, we examine the antiporter activity of the other SLC37 members along with their ability to couple with G6Pase-α. G6PT- and mock-proteoliposomes are used as positive and negative controls, respectively. We show that SLC37A1 and SLC37A2 are ER-associated, P(i-linked antiporters, that can transport G6P. Unlike G6PT, neither is sensitive to chlorogenic acid, a competitive inhibitor of physiological ER G6P transport, and neither couples to G6Pase-α. We conclude that three of the four SLC37 family members are functional sugar-phosphate antiporters. However, only G6PT/SLC37A4 matches the characteristics of the physiological ER G6P transporter, suggesting the other SLC37 proteins have roles independent of blood glucose homeostasis.

Products and stability of phosphate reactions with lead under freeze-thaw cycling in simple systems

Energy Technology Data Exchange (ETDEWEB)

Hafsteinsdottir, Erla G., E-mail: erla.hafsteinsdottir@gmail.com [Department of Environment and Geography, Macquarie University, NSW 2109 (Australia); White, Duanne A., E-mail: duanne.white@mq.edu.au [Department of Environment and Geography, Macquarie University, NSW 2109 (Australia); Gore, Damian B., E-mail: damian.gore@mq.edu.au [Department of Environment and Geography, Macquarie University, NSW 2109 (Australia); Stark, Scott C., E-mail: scott.stark@aad.gov.au [Environmental Protection and Change, Australian Antarctic Division, Department of Sustainability, Environment, Water, Population and Communities, Tasmania 7050 (Australia)

2011-12-15

Orthophosphate fixation of metal contaminated soils in environments that undergo freeze-thaw cycles is understudied. Freeze-thaw cycling potentially influences the reaction rate, mineral chemical stability and physical breakdown of particles during fixation. This study determines what products form when phosphate (triple superphosphate [Ca(H{sub 2}PO{sub 4}){sub 2}] or sodium phosphate [Na{sub 3}PO{sub 4}]) reacts with lead (PbSO{sub 4} or PbCl{sub 2}) in simple chemical systems in vitro, and assesses potential changes in formation during freeze-thaw cycles. Systems were subjected to multiple freeze-thaw cycles from +10 deg. C to -20 deg. C and then analysed by X-ray diffractometry. Pyromorphite formed in all systems and was stable over multiple freeze-thaw cycles. Low temperature lead orthophosphate reaction efficiency varied according to both phosphate and lead source; the most time-efficient pyromorphite formation was observed when PbSO{sub 4} and Na{sub 3}PO{sub 4} were present together. These findings have implications for the manner in which metal contaminated materials in freezing ground can be treated with phosphate. - Highlights: > Formation of lead phosphate products in cold environments is identified. > Potential change in formation during freeze-thaw cycling is assessed. > Lead phosphate reaction efficiency varies according to phosphate and lead source. > Pyromorphite formation is stable during 240 freeze-thaw cycles. - Pyromorphite, formed from Pb phosphate fixation, is stable during multiple freeze-thaw cycles but the efficiency of the fixation depends on the phosphate source and the type of Pb mineral.

Phosphate-enhanced cytotoxicity of zinc oxide nanoparticles and agglomerates.

Science.gov (United States)

Everett, W Neil; Chern, Christina; Sun, Dazhi; McMahon, Rebecca E; Zhang, Xi; Chen, Wei-Jung A; Hahn, Mariah S; Sue, H-J

2014-02-10

Zinc oxide (ZnO) nanoparticles (NPs) have been found to readily react with phosphate ions to form zinc phosphate (Zn3(PO4)2) crystallites. Because phosphates are ubiquitous in physiological fluids as well as waste water streams, it is important to examine the potential effects that the formation of Zn3(PO4)2 crystallites may have on cell viability. Thus, the cytotoxic response of NIH/3T3 fibroblast cells was assessed following 24h of exposure to ZnO NPs suspended in media with and without the standard phosphate salt supplement. Both particle dosage and size have been shown to impact the cytotoxic effects of ZnO NPs, so doses ranging from 5 to 50 μg/mL were examined and agglomerate size effects were investigated by using the bioinert amphiphilic polymer polyvinylpyrrolidone (PVP) to generate water-soluble ZnO ranging from individually dispersed 4 nm NPs up to micron-sized agglomerates. Cell metabolic activity measures indicated that the presence of phosphate in the suspension media can led to significantly reduced cell viability at all agglomerate sizes and at lower ZnO dosages. In addition, a reduction in cell viability was observed when agglomerate size was decreased, but only in the phosphate-containing media. These metabolic activity results were reflected in separate measures of cell death via the lactate dehydrogenase assay. Our results suggest that, while higher doses of water-soluble ZnO NPs are cytotoxic, the presence of phosphates in the surrounding fluid can lead to significantly elevated levels of cell death at lower ZnO NP doses. Moreover, the extent of this death can potentially be modulated or offset by tuning the agglomerate size. These findings underscore the importance of understanding how nanoscale materials can interact with the components of surrounding fluids so that potential adverse effects of such interactions can be controlled. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Development of a phosphating process for corrosion protection in NdFeB magnets

International Nuclear Information System (INIS)

Silva, Adonis Marcelo Saliba

2001-01-01

NdFeB magnets are important materials, which produce better energy efficiency in electrical devices, but they are rather vulnerable to corrosion. In this study, a phosphating treatment for protection against corrosion of NdFeB magnets has been investigated. Phosphating is generally used as a pretreatment in the application of protective coatings. This treatment increases the corrosion assistance in defective areas of the coating as well as improves the adhesion between coating and substrate. A commercial NdFeB magnet produced by powder metallurgy has been used and the effect of the following parameters on phosphating was studied: time of phosphating; pH of phosphating solution; anodic polarization and molybdate addition to the phosphating solution. The results showed a significant increase in the corrosion resistance of magnets phosphated in a solution concentrated between 10-20 g/L NaH 2 PO 4 , pH in the range of 3 to 4.6, acidulated preferably with H 3 PO 4 at room temperature (20±1) deg C. Conversion coatings formed at solutions of pH 3.8 showed better corrosion resistance. Phosphating times longer than 4 hours increased the magnet corrosion resistance 10 to 20 times. This resistance improves with higher immersion times. Anodic polarization of the magnet in the range 200-400 mV SCE accelerated phosphating. Results indicated that molybdate interacts preferentially with Nd rich phase of the magnet. In addition to the newly developed technology in this work for NdFeB corrosion protection, two methodologies have been introduced to facilitate electrochemical analyses: selection of samples of similar electrochemical behavior, based on the current density after 200s of constant anodic polarization; and evaluation of the corrosion protection provided by conversion coatings by monitoring of gas evolution during corrosion in acid solution. (author)

Triphenyl phosphate allergy from spectacle frames

DEFF Research Database (Denmark)

Carlsen, L; Andersen, K E; Egsgaard, Helge

1986-01-01

A case of triphenyl phosphate allergy from spectacle frames is reported. Patch tests with analytical grade triphenyl phosphate, tri-m-cresyl phosphate, and tri-p-cresyl phosphate in the concentrations 5%, 0.5% and 0.05% pet. showed positive reactions to 0.05% triphenyl phosphate and 0.5% tri......-m-cresyl phosphate, but no reaction to tri-p-cresyl phosphate. Gas chromatography of the tricresyl phosphate 5% pet. patch test material supplied from Trolab showed that it contained a mixture of a wide range of triaryl phosphates, including 0.08% triphenyl phosphate which is above the threshold for detecting...

Sorption behavior of Zn(II) ions on synthetic apatitic calcium phosphates

Science.gov (United States)

Sebei, Haroun; Pham Minh, Doan; Nzihou, Ange; Sharrock, Patrick

2015-12-01

The synthesis, characterization and the reactivity of apatitic calcium phosphates (Ca-HA, chemical formula Ca10(PO4)6(OH)2) is reported. Calcium carbonate (CaCO3) and potassium dihydrogen orthophosphate (KH2PO4) were selected as economical starting materials for the synthesis of Ca-HA under atmospheric conditions. Monocalcium phosphate monohydrate (MCPM), dicalcium phosphate dihydrate (DCPD), and octacalcium phosphate pentahydrate (OCP) were identified as the main intermediates of the synthesis reaction. The product obtained after 48 h of reaction contains mainly low-crystalline Ca-HA and small amounts of other calcium phosphates such as octacalcium phosphate (OCP), B-type carbonate apatite (CAP), as well as unreacted calcium carbonate. This Ca-HA was found to be active for the removal of Zn2+ from an aqueous solution. Its sorption capacity reached up to 120 mg of Zn2+ per g of Ca-HA powder after 24 h of reaction. The monitoring of soluble Zn, Ca and P during the sorption experiment allowed characterizing the mechanism of Zn uptake. Dissolution-precipitation, ionic exchange and surface complexation are the three main mechanisms involved in the sorption processes. The contribution of these mechanisms is discussed in detail.

Structural study and physical properties of a new phosphate KCuFe(PO4)2

International Nuclear Information System (INIS)

Badri, Abdessalem; Hidouri, Mourad; Lopez, Maria Luisa; Pico, Carlos; Wattiaux, Alain; Ben Amara, Mongi

2011-01-01

Single crystals of a new phosphate KCuFe(PO 4 ) 2 have been prepared by the flux method and its structural and physical properties have been investigated. This compound crystallizes in the monoclinic system with the space group P2 1 /n and its parameters are: a=7.958(3) A, b=9.931(2) A, c=9.039(2) A, β=115.59(3) o and Z=4. Its structure consists of FeO 6 octahedra sharing corners with Cu 2 O 8 units of edge-sharing CuO 5 polyhedra to form undulating chains extending infinitely along the b-axis. These chains are connected by the phosphate tetrahedra giving rise to a 3D framework with six-sided tunnels parallel to the [101] direction, where the K + ions are located. The Moessbauer spectroscopy results confirm the exclusive presence of octahedral Fe 3+ ions. The magnetic measurements show the compound to be antiferromagnetic with C m =5.71 emu K/mol and θ=-156.5 K. The derived experimental effective moment μ ex =6.76μ B is somewhat higher than the theoretical one of μ th =6.16μ B , calculated taking only into account the spin contribution for Fe 3+ and Cu 2+ cations. Electrical measurements allow us to obtain the activation energy (1.22 eV) and the conductivity measurements suggest that the charge carriers through the structure are the potassium cations. -- Graphical abstract: A projection along the [101] direction of the structure showing the six-edged tunnels, occupied by the K + ions. Display Omitted Highlights: → The reported structure is of a new type. → The structural model is supported by a Moessbauer spectroscopy study. → The magnetic susceptibility results are reported. → The electrical properties are discussed.

Phosphate solubilization and promotion of maize growth in a calcareous soil by penicillium oxalicum P4 and aspergillus niger P85

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Alternative tactics for improving phosphorus nutrition in crop production are needed in China and elsewhere as the over-application of phosphatic fertilizers can adversely impact agricultural sustainability. Penicillium oxalicum P4 and Aspergillus niger P85 were isolated from a calcareous soil in C...

Light-Induced Surface Reactions at the Bismuth Vanadate/Potassium Phosphate Interface.

Science.gov (United States)

Favaro, Marco; Abdi, Fatwa F; Lamers, Marlene; Crumlin, Ethan J; Liu, Zhi; van de Krol, Roel; Starr, David E

2018-01-18

Bismuth vanadate has recently drawn significant research attention as a light-absorbing photoanode due to its performance for photoelectrochemical water splitting. In this study, we use in situ ambient pressure X-ray photoelectron spectroscopy with "tender" X-rays (4.0 keV) to investigate a polycrystalline bismuth vanadate (BiVO 4 ) electrode in contact with an aqueous potassium phosphate (KPi) solution at open circuit potential under both dark and light conditions. This is facilitated by the creation of a 25 to 30 nm thick electrolyte layer using the "dip-and-pull" method. We observe that under illumination bismuth phosphate forms on the BiVO 4 surface leading to an increase of the surface negative charge. The bismuth phosphate layer may act to passivate surface states observed in photoelectrochemical measurements. The repulsive interaction between the negatively charged surface under illumination and the phosphate ions in solution causes a shift in the distribution of ions in the thin aqueous electrolyte film, which is observed as an increase in their photoelectron signals. Interestingly, we find that such changes at the BiVO 4 /KPi electrolyte interface are reversible upon returning to dark conditions. By measuring the oxygen 1s photoelectron peak intensities from the phosphate ions and liquid water as a function of time under dark and light conditions, we determine the time scales for the forward and reverse reactions. Our results provide direct evidence for light-induced chemical modification of the BiVO 4 /KPi electrolyte interface.

Evaluating and quantifying the liming potential of phosphate rocks

International Nuclear Information System (INIS)

Sikora, F.J.

2002-01-01

The liming potential of phosphate rock was evaluated with theoretical calculations and quantified by laboratory titration and soil incubation. Three anions present in the carbonate apatite structure of phosphate rock that can consume protons and cause an increase in pH when dissolved from apatite are PO 4 3- , CO 3 2- , and F - . The pKa for HF is so low that F - has very little effect on increasing pH. The pKa for 2 protons on H 2 PO 4 - and H 2 CO 3 are sufficiently high enough to cause an increase in pH with PO 4 3- and CO 3 2- released into solution if the pH range is between 4 and 6. Because of the greater molar quantity of PO 4 3- compared toCO 3 2- , PO 4 3- exerts a greater affect on the liming potential of P rock. For a variety of phosphate rocks with a axes ranging from 9.322 to 9.374 A in the carbonate apatite structure, the theoretical % calcium carbonate equivalence (CCE) ranges from 59.5 to 62%. With the presence of gangue carbonate minerals from 2.5 to 10% on a weight basis in the phosphate rocks, the theoretical %CCE ranges from 59.5 to 63.1%. Use of AOAC method 955.01 for quantifying the %CCE of North Carolina phosphate rock (NCPR) and Idaho phosphate rock (IDPR) resulted in %CCE ranging from 39.9 to 53.7% which were less than the theoretical values. The lower values measured in the AOAC method was presumed to be due to formation of CaHPO 4 or CaHPO 4 ·2H 2 O precipitates which would result in less than 2 protons neutralized per mole of PO 4 3- released from carbonate apatite. The highly concentrated solution formed in the method was considered not indicative of a soil solution and thus determined %CCE values would be suspect. A soil incubation study was conducted to determine a more appropriate %CCE value in a soil environment using Copper Basin, Tennessee soil with a soil pH of 4.2. Agricultural limestone, NCPR, IDPR, and a granulated IDPR were added to 100 g of soil at rates of 0.1, 0.3, 1, 3, and 10 g/kg soil, incubated for 105 days at field

Polypyrrole electrodeposited on copper from an aqueous phosphate solution: Corrosion protection properties

OpenAIRE

Redondo, Clara; Breslin, Carmel B.

2007-01-01

Highly adherent and homogenous polypyrrole films were electrodeposited at copper from a dihydrogen phosphate solution. The polypyrrole films were electrosynthesized in the overoxidized state by cycling the copper electrode from –0.4 to 1.8 V (SCE) in a pyrrole-containing phosphate solution. The growth of the polypyrrole films was facilitated by the initial oxidation of the copper electrode in the phosphate solution to generate a mixed copper–phosphate, copper oxide or hydroxide layer. This la...

Eigenstates and radiative transition probabilities for Tm3+(4f12) in phosphate and tellurite glasses

International Nuclear Information System (INIS)

Spector, N.; Reisfeld, R.; Boehm, L.

1977-01-01

Electronic wavefunctions of Tm 3+ in intermediate coupling were obtained and used to calculate the Usup((lambda)) matrix elements between all possible states of the 4f 12 configuration. The Judd-Ofelt intensity parameters Ωsub(lambda) obtained for Tm 3+ in phosphate and tellurite glasses were used in conjunction with the Usup((lambda))'s to calculate the forced electric dipole line strengths. The total electric and magnetic radiative transition probabilities are calculated. The entire theoretical spectrum involving the ground and excited levels (from 129 nm to 16447 nm) is given. (Auth.)

Sphingosine 1-phosphate lyase enzyme assay using a BODIPY-labeled substrate

International Nuclear Information System (INIS)

Bandhuvula, Padmavathi; Li Zaiguo; Bittman, Robert; Saba, Julie D.

2009-01-01

Sphingosine 1-phosphate lyase (SPL) is responsible for the irreversible catabolism of sphingosine 1-phosphate, which signals through five membrane receptors to mediate cell stress responses, angiogenesis, and lymphocyte trafficking. The standard assay for SPL activity utilizes a radioactive dihydrosphingosine 1-phosphate substrate and is expensive and cumbersome. In this study, we describe an SPL assay that employs an ω-labeled BODIPY-sphingosine 1-phosphate substrate, allowing fluorescent product detection by HPLC and incorporating advantages of the BODIPY fluorophore. The major aldehyde product is confirmed by reaction with 2,4-dinitrophenylhydrazine. The SPL-catalyzed reaction is linear over a 30 min time period and yields a K m of 35 μM for BODIPY-sphingosine 1-phosphate.

Gadolinium-hydrogen ion exchange of zirconium phosphate

Science.gov (United States)

Liu, D. C.; Power, J. L.

1972-01-01

The Gd(+3)/H(+) ion exchange on a commercial zirconium phosphate ion exchanger was investigated in chloride, sulfate, and phosphate solutions of Gd(+3) at gadolinium concentrations of 0.001 to 1 millimole per cc and in the pH range of 0 to 3.5. Relatively low Gd(+3) capacities, in the range of 0.01 to 0.1 millimole per g of ion exchanger were found at room temperature. A significant difference in Gd(+3) sorption was observed, depending on whether the ion exchanger was converted from initial conditions of greater or lesser Gd(+3) sorption than the specific final conditions. Correlations were found between decrease in Gd(+3) capacity and loss of exchanger phosphate groups due to hydrolysis during washing and between increase in capacity and treatment with H3PO4. Fitting of the experimental data to ideal ion exchange equilibrium expressions indicated that each Gd(+3) ion is sorbed on only one site of the ion exchanger. The selectivity quotient was determined to be 2.5 + or - 0.4 at room temperature on gadolinium desorption in chloride solutions.

Infrared spectroscopy of different phosphates structures.

Science.gov (United States)

Jastrzębski, W; Sitarz, M; Rokita, M; Bułat, K

2011-08-15

Infrared (IR) spectroscopic studies of mineral and synthetic phosphates have been presented. The interpretation of the spectra has been preceded by the isolated [PO(4)](3-) tetrahedron spectra analyse. The K(3)PO(4) saturated aqueous solution was measured in the special cell for liquids. The obtained IR results have been compared with the theoretical number of IR-active modes. The number and positions of the bands due to P-O vibrations have been established. The phase composition of the phosphates has been determined using XRD and IR spectroscopy methods. The influence of non-tetrahedral cations on the shape of the spectra and the positions of bands has been analysed and the crystalline field splitting effect has been discussed. Copyright © 2010 Elsevier B.V. All rights reserved.

Phosphate limitation induces sporulation in the chytridiomycete Blastocladiella emersonii.

Science.gov (United States)

Bongiorno, Vagner Alexandre; Ferreira da Cruz, Angela; Nunis da Silva, Antonio; Corrêa, Luiz Carlos

2012-09-01

The cell cycle is controlled by numerous mechanisms that ensure correct cell division. If growth is not possible, cells may eventually promote autophagy, differentiation, or apoptosis. Microorganisms interrupt their growth and differentiate under general nutrient limitation. We analyzed the effects of phosphate limitation on growth and sporulation in the chytridiomycete Blastocladiella emersonii using kinetic data, phase-contrast, and laser confocal microscopy. Under phosphate limitation, zoospores germinated and subsequently formed 2-4 spores, regardless of the nutritional content of the medium. The removal of phosphate at any time during growth induced sporulation of vegetative cells. If phosphate was later added to the same cultures, growth was restored if the cells were not yet committed to sporulation. The cycles of addition and withdrawal of phosphate from growth medium resulted in cycles of germination-growth, germination-sporulation, or germination-growth-sporulation. These results show that phosphate limitation is sufficient to interrupt cell growth and to induce complete sporulation in B. emersonii. We concluded that the determination of growth or sporulation in this microorganism is linked to phosphate availability when other nutrients are not limiting. This result provides a new tool for the dissection of nutrient-energy and signal pathways in cell growth and differentiation.

Performance of pineapple slips inoculated with diazotrophic phosphate-solubilizing bacteria and rock phosphate

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Lílian Estrela Borges Baldotto

2014-06-01

Full Text Available Besides fixing N2, some diazotrophic bacteria or diazotrophs, also synthesize organic acids and are able to solubilize rock phosphates, increasing the availability of P for plants. The application of these bacteria to pineapple leaf axils in combination with rock phosphate could increase N and P availability for the crop, due to the bacterial activity of biological nitrogen fixation and phosphate solubilization. The objectives of this study were: (i to select and characterize diazotrophs able to solubilize phosphates in vitro and (ii evaluate the initial performance of the pineapple cultivars Imperial and Pérola in response to inoculation with selected bacteria in combination with rock phosphate. The experiments were conducted at Universidade Estadual do Norte Fluminense Darcy Ribeiro, in 2009. In the treatments with bacteria the leaf contents of N, P and K were higher than those of the controls, followed by an increase in plant growth. These results indicate that the combined application of diazotrophic phosphate-solubilizing bacteria Burkholderia together with Araxá rock phosphate can be used to improve the initial performance of pineapple slips.

How do arbuscular mycorrhizal fungi handle phosphate? New insight into fine-tuning of phosphate metabolism.

Science.gov (United States)

Ezawa, Tatsuhiro; Saito, Katsuharu

2018-04-27

Contents Summary I. Introduction II. Foraging for phosphate III. Fine-tuning of phosphate homeostasis IV. The frontiers: phosphate translocation and export V. Conclusions and outlook Acknowledgements References SUMMARY: Arbuscular mycorrhizal fungi form symbiotic associations with most land plants and deliver mineral nutrients, in particular phosphate, to the host. Therefore, understanding the mechanisms of phosphate acquisition and delivery in the fungi is critical for full appreciation of the mutualism in this association. Here, we provide updates on physical, chemical, and biological strategies of the fungi for phosphate acquisition, including interactions with phosphate-solubilizing bacteria, and those on the regulatory mechanisms of phosphate homeostasis based on resurveys of published genome sequences and a transcriptome with reference to the latest findings in a model fungus. For the mechanisms underlying phosphate translocation and export to the host, which are major research frontiers in this field, not only recent advances but also testable hypotheses are proposed. Lastly, we briefly discuss applicability of the latest tools to gene silencing in the fungi, which will be breakthrough techniques for comprehensive understanding of the molecular basis of fungal phosphate metabolism. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

Formulation of single super phosphate fertilizer from rock phosphate of Hazara, Pakistan

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Matiullah Khan

2012-05-01

Full Text Available Phosphorus deficiency is wide spread in soils of Pakistan. It is imperative to explore the potential and economics of indigenous Hazara rock phosphate for preparation of single super phosphate fertilizer. For the subject study rock phosphate was collected from Hazara area ground at 160 mesh level with 26% total P2O5 content for manual preparation of single super phosphate fertilizer. The rock phosphate was treated with various concentrations of sulfuric acid (98.9%, diluted or pure in the field. The treatments comprised of 20 and 35% pure acid and diluted with acid-water ratios of 1:5, 1:2, 1:1 and 2:1 v/v for acidulation at the rate of 60 liters 100 kg-1 rock phosphate. The amount was prior calculated in the laboratory for complete wetting of rock phosphate. A quantity of 150 kg rock phosphate was taken as treatment. The respective amount of acid was applied with the spray pump of stainless steel or poured with bucket. After proper processing, chemical analysis of the products showed a range of available P2O5 content from 9.56 to 19.24% depending upon the amount of acid and its dilution. The results reveal at that 1:1 dilutions gave the highest P2O5 content (19.24%, lowest free acid (6 % and 32% weight increase. The application of acid beyond or below this combination either pure or diluted gave hygroscopic product and higher free acids. The cost incurred upon the manual processing was almost half the prevailing rates in the market. These results lead to conclude that application of sulfuric acid at the rate of 60 liters 100 kg-1 with the dilution of 50% (v/v can yield better kind of SSP from Hazara rock phosphate at lower prices.

Microbial Leaching of Some Valuable Elements From Egyptian Phosphate Rock

International Nuclear Information System (INIS)

Kamal, H.M.; Hassanein, R.A.; Mahdy, H.M.A.; Mahmoud, K.F.; Abouzeid, M.A.

2012-01-01

Four phosphate rock samples representing different phosphate mineralization modes in Egypt were selected from Abu Tartar, Nile valley and Red sea areas. Factors affecting the phosphate rock solubilization and some of the contained valuable elements by Aspergillus niger, Penicillium sp. and Pseudomonas fluorescence, were studied with especial orientation towards the completion of phosphate rock samples solubilization especially die low grade one. Effect of nitrogen source type on leaching efficiency by Aspergillus niger when two nitrogen sources on the phosphate bioleaching efficiency, it is clear that the ammonium chloride is more favorable as nitrogen source than sodium nitrate in the bioleaching of phosphate rocks. When Aspergillus niger was applied under die following conditions: 50 g/1 of sucrose as a carbon source, 0.1 N of ammonium chloride as a nitrogen source, 10 days incubation period, 0.5% solid: liquid ratio for P 2 O 5 and 5% for U and REE and - 270 mesh of grain size. The optimum leaching of P 2 O 5 , U and REE from phosphate rock samples reached (23.27%, 17.4%, 11.4%, respectively), while at -60 mesh they reached to 16.58%, 28.9%, 30.2% respectively. The optimum conditions for the maximal leaching efficiencies of P 2 O 5 , U and REE when applying the Penicillium sp. from the phosphate rock samples were: 100 g/1 of sucrose as a carbon source for P 2 O 5 and U and 10 g/1 for REE, 7,15 and 10 days incubation period for P 2 O 5 , U and REE, respectively, 0.5% solid: liquid ratio for P 2 O 5 and 5% for U and REE. Finally, the application of phosphate rock samples grinded to -270 mesh of grain size for P 2 O 5 and (-60 to -140) for U and REE. The studied leaching efficiency of P 2 O 5 , U and REE gave at -270 mesh 33.66%, 24.3%, 15.9% respectively, while at -60 mesh they gave 33.76%, 26.7%, 17.8% and at -140 mesh gave 31.32%, 27.9%, 17.6%, respectively.The optimum conditions for the P 2 O 5 leaching efficiency when applying the Pseudomonas fluorescence were

Variscite (AlPO4 2H2O from Cioclovina Cave (Sureanu Mountains, Romania: a tale of a missing phosphate

Directory of Open Access Journals (Sweden)

Bogdan P. Onac

2004-04-01

Full Text Available Recent investigations on a phosphatized sediment sequence in the Cioclovina Cave led to the identification of a second occurrence in Romania (first time in the cave environment of variscite, AlPO4·2H2O. The mineral exists as dull-white, tiny crusts and veinlets within the thick argillaceous material accumulated on the cave floor. Under scanning electron microscope (SEM variscite appears as subhedral to euhedral micron-size crystals. The {111} pseudo-octahedral form is rather common. Variscite was further characterized by means of X-ray diffraction, thermal, vibrational FT-IR and FT-Raman spectroscopy, and by SEM energy-dispersive spectrometry (EDS. The calculated orthorhombic cell parameters are a = 9.823(4, b = 8.562(9, c = 9.620(5 Å, and V = 809.167(6 Å3. The ED spectrum of variscite shows well-resolved Al and P lines confirming thus the presence of the major elements in our compound. The formation of variscite is attributed to the reaction between the phosphate-rich leachates derived from guano and the underlying clay sediments.

The Properties of Sintered Calcium Phosphate with [Ca]/[P] = 1.50

Directory of Open Access Journals (Sweden)

Moo-Chin Wang

2012-10-01

Full Text Available In order to obtain the properties of the sintered as-dried calcium phosphate with [Ca]/[P] = 1.50, the characteristics of sintered pellets have been investigated using X-ray diffraction (XRD, inductively coupled plasma-mass spectrometry (ICP-MS, Fourier-transform infrared (FT-IR spectra, Vickers hardness indentation and scanning electron microscopy (SEM. When the pellet samples were sintered between 700 °C and 1200 °C for 4 h, the hydroxyapatite (Ca10(PO46(OH2, HA still maintained the major phase, accompanied with the rhenanite (NaCaPO4 as the secondary phase and β-tricalcium phosphate (β-Ca3(PO42, β-TCP as the minor phases. In addition, the HA partially transformed to α-tricalcium phosphate (α-Ca3(PO42, α-TCP and tetracalcium phosphate (Ca4(PO42O, TTCP, when the pellet samples were sintered at 1300 °C and 1400 °C, respectively, for 4 h. The maximum density and Vickers Hardness (HV of sintered pellet samples were 2.85 g/cm3 (90.18% theoretical density (T.D. and 407, which appeared at 1200 °C and 900 °C, respectively.

Integrated assessment of the phosphate industry

International Nuclear Information System (INIS)

Ryan, M.T.; Cotter, S.J.

1980-05-01

The phosphate industry in the United States includes three major activities, namely, mining and milling of phosphate rock, phosphate product manufacture, and phosphate product use. Phosphatic materials contain uranium, thorium, and their decay products in greater than background amounts. This assessment of the radiological impacts associated with the redistribution of radioactive components of phosphate materials may provide insight into the effects of uranium extraction from phosphate materials for use in the nuclear fuel cycle

Advances in process technology for eco-friendly phosphates by separation of radionuclides

Energy Technology Data Exchange (ETDEWEB)

Singh, H; Mukherjee, T K [Uranium and Rare Earths Extraction Division, Bhabha Atomic Research Centre, Mumbai (India)

1994-06-01

Phosphates are used in the industry for fertilizers, industrial chemicals (detergents, water-treatment chemicals) and food-additives. The source of phosphates for the industry is rock-phosphate. Over 90% of phosphate rocks of the world are associated with uranium and its radioactive daughter products. Processing and use of phosphates is accompanied by radiation hazards. The concentration of radionuclides is low, but in view of large number of persons exposed to the hazards, the cumulative societal pollution load is high, and a matter of concern for international organisations. Chemical engineering techniques have been developed for the reduction of societal radiation hazard from the phosphates. In this paper, brief details of the process and developmental efforts in India are described. (author). 4 refs., 1 fig.

Charge Localization in the Lithium Iron Phosphate Li3Fe2(PO4)3at High Voltages in Lithium-Ion Batteries

DEFF Research Database (Denmark)

Younesi, Reza; Christiansen, Ane Sælland; Loftager, Simon

2015-01-01

Possible changes in the oxidation state of the oxygen ion in the lithium iron phosphate Li3Fe2(PO4)3 at high voltages in lithium-ion (Li-ion) batteries are studied using experimental and computational analysis. Results obtained from synchrotron-based hard X-ray photoelectron spectroscopy...

Reaction between CO2 and phosphate to form carboxyphosphate?

International Nuclear Information System (INIS)

Knight, W.B.; Attwood, P.V.; Cleland, W.W.

1986-01-01

Carboxyphosphate (I) is thought to be an intermediate in the enzymic carboxylation of biotin by bicarbonate and MgATP, and a plausible mechanism of carboxyl transfer to the enolate of biotin involves decarboxylation to CO 2 and phosphate. Such a process would have to be reversible, however, as carboxylase reactions are reversible. To test this possibility, the authors undertook the synthesis of I under anhydrous conditions with a high mole fraction of CO 2 present. CO 2 was distilled into capillary tubes under vacuum containing dry tris-(tetrabutyl-ammonium)-phosphate in dimethylformamide. The tubes were sealed and warmed to -10 or 20 0 C and examined by 31 P NMR. Two resonances (1.7 ppm and -5.0 ppm) in addition to phosphate (3.3 ppm) were observed. The relative ratio of each peak to the phosphate one was dependent on the temperature and the concentrations of PO 4 3- and CO 2 . Upon freezing the tubes, cracking them, and release of the CO 2 , the two additional species decomposed slowly to PO 4 3- , and more rapidly to HPO 4 3- upon the addition of H 2 O. Under some conditions they observed an additional resonance (-7.0 ppm) which is most likely pyrophosphate (PP/sub i/). At high concentrations of PO 4 3- and CO 2 , PP/sub i/ was produced and precipitated from solution. The production of PP/sub i/ is most easily explained by attack of PO 4 3- on I. They are currently trying to identify the unknown species observed in the 31 P NMR spectra

Deformation of Olivine at Subduction Zone Conditions Determined from In situ Measurements with Synchrotron Radiation

Energy Technology Data Exchange (ETDEWEB)

H Long; D Weidner; L Li; J Chen; L Wang

2011-12-31

We report measurements of the deformation stress for San Carlos olivine at pressures of 3-5 GPa, temperatures of 25-1150 C, and strain rates of 10{sup -7}-10{sup -5} s{sup -1}. We determine a deformation stress of approximately 2.5 GPa that is relatively temperature and strain rate independent in the temperature range of 400-900 C. The deformation experiments have been carried out on a deformation DIA (D-DIA) apparatus, Sam85, at X17B2, NSLS. Powder samples are used in these experiments. Enstatite (MgSiO{sub 3}) (3-5% total quality of sample) is used as the buffer to control the activity of silica. Ni foil is used in some experiments to buffer the oxygen fugacity. Water content is confirmed by IR spectra of the recovered samples. Samples are compressed at room temperature and are then annealed at 1200 C for at least 2 h before deformation. The total (plastic and elastic) strains (macroscopic) are derived from the direct measurements of the images taken by X-ray radiograph technique. The differential stresses are derived from the diffraction determined elastic strains. In the regime of 25-400 C, there is a small decrease of stress at steady state as temperature increases; in the regime of 400 C to the 'transition temperature', the differential stress at steady state ({approx}2.5 GPa) is relatively insensitive to the changes of temperature and strain rate; however, it drastically decreases to about 1 GPa and becomes temperature-dependent above the transition temperature and thereafter. The transition temperature is near 900 C. Above the transition temperature, the flow agrees with power law creep measurements of previous investigations. The anisotropy of differential stress in individual planes indicates that the deformation of olivine at low temperature is dominated by [0 0 1](1 0 0). Accounting to a slower strain rate in the natural system, the transition temperature for the olivine in the slab is most likely in the range of 570-660 C.

Characterization, Leaching, and Filtration Testing for Bismuth Phosphate Sludge (Group 1) and Bismuth Phosphate Saltcake (Group 2) Actual Waste Sample Composites

International Nuclear Information System (INIS)

Lumetta, Gregg J.; Buck, Edgar C.; Daniel, Richard C.; Draper, Kathryn; Edwards, Matthew K.; Fiskum, Sandra K.; Hallen, Richard T.; Jagoda, Lynette K.; Jenson, Evan D.; Kozelisky, Anne E.; MacFarlan, Paul J.; Peterson, Reid A.; Shimskey, Rick W.; Sinkov, Sergey I.; Snow, Lanee A.

2009-01-01

A testing program evaluating actual tank waste was developed in response to Task 4 from the M-12 External Flowsheet Review Team (EFRT) issue response plan.() The test program was subdivided into logical increments. The bulk water-insoluble solid wastes that are anticipated to be delivered to the Waste Treatment and Immobilization Plant (WTP) were identified according to type such that the actual waste testing could be targeted to the relevant categories. Eight broad waste groupings were defined. Samples available from the 222S archive were identified and obtained for testing. The actual waste-testing program included homogenizing the samples by group, characterizing the solids and aqueous phases, and performing parametric leaching tests. Two of the eight defined groups - bismuth phosphate sludge (Group 1) and bismuth phosphate saltcake (Group 2) - are the subjects of this report. The Group 1 waste was anticipated to be high in phosphorus and was implicitly assumed to be present as BiPO4 (however, results presented here indicate that the phosphate in Group 1 is actually present as amorphous iron(III) phosphate). The Group 2 waste was also anticipated to be high in phosphorus, but because of the relatively low bismuth content and higher aluminum content, it was anticipated that the Group 2 waste would contain a mixture of gibbsite, sodium phosphate, and aluminum phosphate. Thus, the focus of the Group 1 testing was on determining the behavior of P removal during caustic leaching, and the focus of the Group 2 testing was on the removal of both P and Al. The waste-type definition, archived sample conditions, homogenization activities, characterization (physical, chemical, radioisotope, and crystal habit), and caustic leaching behavior as functions of time, temperature, and hydroxide concentration are discussed in this report. Testing was conducted according to TP-RPP-WTP-467

Procedure for the separation of cerium from rare earth phosphate mixtures

International Nuclear Information System (INIS)

Richter, H.; Grauss, H.; Schmitt, A.; Schade, H.; Lindeholz, M.; Lorenz, E.; Weickart, J.

1986-01-01

The invention is concerned with a procedure for the separation of cerium from rare earth concentrates originating from the partial neutralization of nitric crude phosphate decomposition solutions without preceding elimination of impurities from the raw material. The rare earth phosphates are treated with an excess of concentrated nitric acid through which the Ce 3+ , contained in the solution, is oxidized to Ce 4+ and precipitated as cerium(IV) phosphate by neutralization with alkalis

Effect upon biocompatibility and biocorrosion properties of plasma electrolytic oxidation in trisodium phosphate electrolytes.

Science.gov (United States)

Kim, Yu-Kyoung; Park, Il-Song; Lee, Kwang-Bok; Bae, Tae-Sung; Jang, Yong-Seok; Oh, Young-Min; Lee, Min-Ho

2016-03-01

Surface modification to improve the corrosion resistance and biocompatibility of the Mg-Al-Zn-Ca alloy was conducted via plasma electrolytic oxidation (PEO) in an electrolyte that included phosphate. Calcium phosphate can be easily induced on the surface of a PEO coating that includes phosphate in a physiological environment because Ca(2+) ions in body fluids can be combined with PO4 (3-). Cytotoxicity of the PEO coating formed in electrolytes with various amounts of Na3PO4 was identified. In particular, the effects that PEO films have upon oxidative stress and differentiation of osteoblast activity were studied. As the concentration of Na3PO4 in the electrolyte increased, the oxide layer was found to become thicker, which increased corrosion resistance. However, the PEO coating formed in electrolytes with over 0.2 M of added Na3PO4 exhibited more microcracks and larger pores than those formed in smaller Na3PO4 concentrations owing to a large spark discharge. A nonuniform oxide film that included more phosphate caused more cytotoxicity and oxidative stress, and overabundant phosphate content in the oxide layer interrupted the differentiation of osteoblasts. The corrosion resistance of the magnesium alloy and the thickness of the oxide layer were increased by the addition of Na3PO4 in the electrolyte for PEO treatment. However, excessive phosphate content in the oxide layer led to oxidative stress, which resulted in reduced cell viability and activity.

Zinc phosphate conversion coatings

Science.gov (United States)

Sugama, Toshifumi

1997-01-01

Zinc phosphate conversion coatings for producing metals which exhibit enhanced corrosion prevention characteristics are prepared by the addition of a transition-metal-compound promoter comprising a manganese, iron, cobalt, nickel, or copper compound and an electrolyte such as polyacrylic acid, polymethacrylic acid, polyitaconic acid and poly-L-glutamic acid to a phosphating solution. These coatings are further improved by the incorporation of Fe ions. Thermal treatment of zinc phosphate coatings to generate .alpha.-phase anhydrous zinc phosphate improves the corrosion prevention qualities of the resulting coated metal.

Uptake of CrO42- ions by Fe-treated tri-calcium phosphate

International Nuclear Information System (INIS)

Serrano G, J.; Ramirez S, J. L.; Bonifacio M, J.; Granados C, F.; Badillo A, V. E.

2010-01-01

CrO 4 2- ion adsorption of Fe-treated tri-calcium phosphate was studied by batch experiments as a function of contact time, initial concentration of metal ion and temperature. Adsorption results showed that at ph 5.5 and 1.0 x 10 -4 M chromium concentration the adsorption capacity of Fe-treated tri-calcium phosphate for CrO 4 2- ions was 7.10 x 10 -3 mmol/g. Chromium adsorption data on Fe-treated tri-calcium phosphate at various initial concentration fitted the Freundlich isotherm. By temperature studies the thermodynamic parameters ΔH 0 , ΔG 0 and ΔS 0 were estimated and the obtained results showed that the adsorption reaction was endothermic and spontaneous. (Author)

Effect of exogenous phytase on degradation of inositol phosphate in dairy cows

DEFF Research Database (Denmark)

Brask-Pedersen, Dorte Buus; Glitsø, Lene Vibe; Skov, L.K.

2013-01-01

The effect of exogenous phytase on inositol phosphate degradation in the rumen of dairy cows was investigated in a 4 × 4 Latin square design. Four lactating Danish Holstein cows fitted with ruminal, duodenal, and ileal cannulas were offered a total mixed ration (TMR) with a high content of inositol...... phosphate and supplemented with 1 of 4 concentrations of phytase [none, low, medium, or high, corresponding to 23, 2,023, 3,982, and 6,015 phytase units/kg of dry matter (DM)]. Exogenous phytase lead to a higher rumen pool of phytase. Inositol phosphate content in digesta samples from rumen, duodenum, ileum...... and in samples of the TMR revealed that the exogenous phytase started degrading the inositol phosphate when feeds and phytase were mixed, and thus the InsP6 phosphorus (InsP6-P) content in the TMR was found to decrease with higher doses of phytase (1.69, 1.51, 1.39, and 1.25 g/kg of DM for the none, low, medium...

[H3N(CH2)4NH3]2[Al4(C2O4)(H2PO4)2(PO4)4].4[H2O]: A new layered aluminum phosphate-oxalate

International Nuclear Information System (INIS)

Peng Li; Li Jiyang; Yu Jihong; Li Guanghua; Fang Qianrong; Xu Ruren

2005-01-01

A new layered inorganic-organic hybrid aluminum phosphate-oxalate [H 3 N(CH 2 ) 4 NH 3 ] 2 [Al 4 (C 2 O 4 )(H 2 PO 4 ) 2 (PO 4 ) 4 ].4[H 2 O](AlPO-CJ25) has been synthesized hydrothermally, by using 1,4-diaminobutane (DAB) as structure-directing agent. The structure has been solved by single-crystal X-ray diffraction analysis and further characterized by IR, 31 P MAS NMR, TG-DTA as well as compositional analyses. Crystal data: the triclinic space group P-1, a=8.0484(7) A, b=8.8608(8) A, c=13.2224(11) A, α=80.830(6) deg. , β=74.965(5) deg. , γ=78.782(6) deg. , Z=2, R 1[ I >2 σ ( I )] =0.0511 and wR 2(alldata) =0.1423. The alternation of AlO 4 tetrahedra and PO 4 tetrahedra gives rise to the four-membered corner-sharing chains, which are interconnected through AlO 6 octahedra to form the layered structure with 4,6-net sheet. Interestingly, oxalate ions are bis-bidentately bonded by participating in the coordination of AlO 6 , and bridging the adjacent AlO 6 octahedra. The layers are held with each other through strong H-bondings between the terminal oxygens. The organic ammonium cations and water molecules are located in the large cavities between the interlayer regions. -- Graphical abstract: The alternation of AlO 4 tetrahedra and PO 4 tetrahedra gives rise to the four-membered corner-sharing chains, which are interconnected through AlO 6 octahedra to form the layered structure with 4,6-net sheet. Oxalate ions are bis-bidentately boned by participating in the coordination of AlO 6 , and bridging the adjacent AlO 6 octahedra

Phosphate Recovery from Human Waste via the Formation of Hydroxyapatite during Electrochemical Wastewater Treatment.

Science.gov (United States)

Cid, Clément A; Jasper, Justin T; Hoffmann, Michael R

2018-03-05

Electrolysis of toilet wastewater with TiO 2 -coated semiconductor anodes and stainless steel cathodes is a potentially viable onsite sanitation solution in parts of the world without infrastructure for centralized wastewater treatment. In addition to treating toilet wastewater, pilot-scale and bench-scale experiments demonstrated that electrolysis can remove phosphate by cathodic precipitation as hydroxyapatite at no additional energy cost. Phosphate removal could be predicted based on initial phosphate and calcium concentrations, and up to 80% total phosphate removal was achieved. While calcium was critical for phosphate removal, magnesium and bicarbonate had only minor impacts on phosphate removal rates at concentrations typical of toilet wastewater. Optimal conditions for phosphate removal were 3 to 4 h treatment at about 5 mA cm -2 (∼3.4 V), with greater than 20 m 2 m -3 electrode surface area to reactor volume ratios. Pilot-scale systems are currently operated under similar conditions, suggesting that phosphate removal can be viewed as an ancillary benefit of electrochemical wastewater treatment, adding utility to the process without requiring additional energy inputs. Further value may be provided by designing reactors to recover precipitated hydroxyapatite for use as a low solubility phosphorus-rich fertilizer.

The plastidial 2-C-methyl-D-erythritol 4-phosphate pathway provides the isoprenyl moiety for protein geranylgeranylation in tobacco BY-2 cells.

Science.gov (United States)

Gerber, Esther; Hemmerlin, Andréa; Hartmann, Michael; Heintz, Dimitri; Hartmann, Marie-Andrée; Mutterer, Jérôme; Rodríguez-Concepción, Manuel; Boronat, Albert; Van Dorsselaer, Alain; Rohmer, Michel; Crowell, Dring N; Bach, Thomas J

2009-01-01

Protein farnesylation and geranylgeranylation are important posttranslational modifications in eukaryotic cells. We visualized in transformed Nicotiana tabacum Bright Yellow-2 (BY-2) cells the geranylgeranylation and plasma membrane localization of GFP-BD-CVIL, which consists of green fluorescent protein (GFP) fused to the C-terminal polybasic domain (BD) and CVIL isoprenylation motif from the Oryza sativa calmodulin, CaM61. Treatment with fosmidomycin (Fos) or oxoclomazone (OC), inhibitors of the plastidial 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway, caused mislocalization of the protein to the nucleus, whereas treatment with mevinolin, an inhibitor of the cytosolic mevalonate pathway, did not. The nuclear localization of GFP-BD-CVIL in the presence of MEP pathway inhibitors was completely reversed by all-trans-geranylgeraniol (GGol). Furthermore, 1-deoxy-d-xylulose (DX) reversed the effects of OC, but not Fos, consistent with the hypothesis that OC blocks 1-deoxy-d-xylulose 5-phosphate synthesis, whereas Fos inhibits its conversion to 2-C-methyl-d-erythritol 4-phosphate. By contrast, GGol and DX did not rescue the nuclear mislocalization of GFP-BD-CVIL in the presence of a protein geranylgeranyltransferase type 1 inhibitor. Thus, the MEP pathway has an essential role in geranylgeranyl diphosphate (GGPP) biosynthesis and protein geranylgeranylation in BY-2 cells. GFP-BD-CVIL is a versatile tool for identifying pharmaceuticals and herbicides that interfere either with GGPP biosynthesis or with protein geranylgeranylation.

Analysis and prediction of stacking sequences in intercalated lamellar vanadium phosphates

Energy Technology Data Exchange (ETDEWEB)

Gautier, Romain [Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS - Ecole Nationale Superieure de Chimie de Rennes (France); Centre Nationale de la Recherche Scientifique (CNRS), Institut des Materiaux Jean Rouxel (IMN), Universite de Nantes (France); Fourre, Yoann; Furet, Eric; Gautier, Regis; Le Fur, Eric [Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS - Ecole Nationale Superieure de Chimie de Rennes (France)

2015-04-15

An approach is presented that enables the analysis and prediction of stacking sequences in intercalated lamellar vanadium phosphates. A comparison of previously reported vanadium phosphates reveals two modes of intercalation: (i) 3d transition metal ions intercalated between VOPO{sub 4} layers and (ii) alkali/alkaline earth metal ions between VOPO{sub 4}.H{sub 2}O layers. Both intercalations were investigated using DFT calculations in order to understand the relative shifts of the vanadium phosphate layers. These calculations in addition to an analysis of the stacking sequences in previously reported materials enable the prediction of the crystal structures of M{sub x}(VOPO{sub 4}).yH{sub 2}O (M = Cs{sup +}, Cd{sup 2+} and Sn{sup 2+}). Experimental realization and structural determination of Cd(VOPO{sub 4}){sub 2}.4H{sub 2}O by single-crystal X-ray diffraction confirmed the predicted stacking sequences. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

On the mechanism of ion exchange in zirconium phosphates

International Nuclear Information System (INIS)

Clearfield, A.; Kalnins, J.M.

1978-01-01

The exchange of transition metal (M 2+ ) ions from manganese through cobalt, nickel, copper to zinc with γ-zirconium phosphate was examined. By using acetate salts the hydrogen ion concentration is kept low enough to achieve high loadings. The fully loaded solids have the composition ZrM(PO 4 ) 2 .4H 2 O. Near quantitative uptakes are achieved at 100 0 C. The interlayer spacings change very little with loading indicating that γ-zirconium phosphate is able to accommodate cations and water molecules without appreciable increase in volume. The copper exchanged phase readily forms an acetylacetonate when shaken with 2,4-pentanedione. (author)

The analysis of impurities in the diuranate-determination of phosphate by phosphomolybdate blue spectrophotometric method

International Nuclear Information System (INIS)

Sun Haobo

2014-01-01

Phosphomolybdenum blue spectrophotometric method was used for determination of phosphate in the diuranate. Diuranate was dissolved in nitric acid solution, in which formed a soluble heteropolyacid complex (namely phosphomolybdenum yellow) due to interaction of phosphate and ammonium molybdate. Then phosphomolybdenum yellow was reduced to phosphomolybdenum blue with Bismuth nitrate as catalyst. Colour intensity at 700 nm is in proportion to the content of phosphate determined by spectrophotometric method. This experiment presents good linearity at the range of 30 μg to 245 μg phosphate, and the relative standard deviation of the experimental result is 2.4%, and the recovery rate is from 95% to 105%. The determination result of phosphate content will not be effected under conditions of 4 mg of SiO 2 , 6 mg of Fe, 400 mg of Cl - and 4.5 mg of Ge in the solution. (author)

Column Experiments to Interpret Weathering in Columbia Hills

Science.gov (United States)

Hausrath, E. M.; Morris, R.V.; Ming, D.W.; Golden, D.C.; Galindo, C.; Sutter, B.

2009-01-01

Phosphate mobility has been postulated as an indicator of early aqueous activity on Mars. In addition, rock surfaces analyzed by the Mars Exploration Rover Spirit are consistent with the loss of a phosphate- containing mineral To interpret phosphate alteration behavior on Mars, we performed column dissolution experiments leaching the primary phases Durango fluorapatite, San Carlos olivine, and basalt glass (Stapafjell Volcano, courtesy of S. Gislason, University of Iceland) [3,4]) with acidic solutions. These phases were chosen to represent quickly dissolving phases likely present in Columbia Hills. Column dissolution experiments are closer to natural dissolution conditions than batch experiments, although they can be difficult to interpret. Acidic solutions were used because the leached layers on the surfaces of these rocks have been interpreted as resulting from acid solutions [5].

Adherence to phosphate binders in hemodialysis patients: prevalence and determinants.

Science.gov (United States)

Van Camp, Yoleen P M; Vrijens, Bernard; Abraham, Ivo; Van Rompaey, Bart; Elseviers, Monique M

2014-12-01

Phosphate control is a crucial treatment goal in end-stage renal disease, but poor patient adherence to phosphate binder therapy remains a challenge. This study aimed to estimate the extent of phosphate binder adherence in hemodialysis patients and to identify potential determinants. Phosphate binder adherence was measured blindly in 135 hemodialysis patients for 2 months using the medication event monitoring system. Patient data, gathered at inclusion through medical records, ad hoc questionnaires and the short form (SF)-36 health survey, included: (1) demographics, (2) perceived side-effects, belief in benefit, self-reported adherence to the therapy, (3) knowledge about phosphate binder therapy, (4) social support, and (5) quality of life (SF-36). Phosphatemia data was collected from charts. 'Being adherent' was defined as missing adherent' as missing adherent. Over the entire 8-week period, 22 % of patients were totally adherent. Mean phosphatemia levels were 0.55 mg/dl lower in adherent than nonadherent patients (4.76 vs. 5.31 mg/dl). Determinants for being totally adherent were living with a partner, higher social support (both were interrelated) and higher physical quality of life. Experiencing intake-related inconvenience negatively affected adherence. The social support and quality of life physical score explained 26 % of the variance in adherence. Phosphate binder nonadherence remains a major problem. Interventions should aim, at least, to improve social support. With few associated factors found and yet low adherence, an individualized approach seems indicated.

[Effects of different amounts of phosphate fertilizers on copper, zinc transfer in red soil under the application of KH2PO4].

Science.gov (United States)

Guo, Liang; Li, Zhong-wu; Huang, Bin; Wang, Yan; Zhang, Yan

2014-09-01

In order to study the effects of different phosphate addition amounts on migration and transformation of heavy metals (Cu, Zn) in soil, an indoor leaching experiment using soil columns was carry out to study the leaching behavior of Cu and Zn. The KH2PO4 was chosen as the fertilizer application at the doses of 5 mg.kg-1, 15 mg.kg-1 and 25 mg.kg-1. The results showed that KH2PO4, could reduce the leachate pH, but different phosphate amounts had little effect on leachate pH, pH in leachate kept rising in the whole leaching process. With the application of KH2PO4, Cu migration was mainly in the surface layer while Zn migrated into deeper soil. Concentrations of Cu, Zn in deep soil leachate were low indicating that it was harmless to the shallow groundwater. After leaching, heavy metals mainly existed in the residual form in soil, the proportion of residual form of Cu was around 60% and the proportion of residual form of Zn was around 40%. High concentration of KH2PO4 helps the transformation of Zn from residual organic combination state to exchange state.

Magnitude and nature of the quadratic electro-optic effect in potassium dihydrogen phosphate and ammonium dihydrogen phosphate crystals

International Nuclear Information System (INIS)

Gunning, Mark J.; Raab, Roger E.; Kucharczyk, Wlodimierz

2001-01-01

Measurements of the magnitude and the sign of certain quadratic electro-optic coefficients of potassium dihydrogen phosphate (KDP) and ammonium dihydrogen phosphate (ADP) were made with an actively stabilized Michelson interferometer. The results obtained for these coefficients are, in units of 10 -20 m 2 V -2 (as opposed to literature values of order 10 -18 m 2 V -2 ), as follows: (KDP)g xxxx =-3.4±0.5, g yyxx =-0.2±0.4, and g zzxx =-0.7±0.4; (ADP)g xxxx =-7.4±1.0, g yyxx =-1.7±0.9, and g zzxx =-1.4±0.9. The quadratic Faust--Henry coefficient describing the lattice and the electronic contributions to the quadratic electro-optic effect in KDP and ADP is estimated from our results. These show that the nonlinear susceptibility responsible for the quadratic electro-optic effect in these crystals is due mainly to nonlinear interactions of the low-frequency electric field with the crystal lattice. Copyright 2001 Optical Society of America

Some peculiarities of the relationship between uranium and phosphate of nodular phosphorites of the Russian Platform

Energy Technology Data Exchange (ETDEWEB)

Kozlov, A A [Vsesoyuznyj Nauchno-Issledovatel' skij Inst. Yadernoj Geofiziki i Geokhimii, Moscow (USSR)

1976-02-01

In nodular phosphorites of the Cenomanian stage of the central regions of the Russian platform the uranium content of phosphate ranges within 20 to 50x10/sup -4/%. The maximum concentrations of uranium are found in amorphous phosphates, the richest in humic colloid. Uranium found in the bone phosphate of fossil reptiles is uniformly distributed throughout the bone tissue area, its content amounting to 30 to 40x10/sup -4/%. As bone phosphate reaches its holocrystalline modification, the uranium compounds are substituted and the uranium concentration decreases to 0.2x10/sup -4/%, i.e. it becomes 200 times lower. The most intensive sorption of uranium by phosphate occurs under the reducing conditions of diagenesis which is characterized by the most comprehensive combination of uranium-sorption factors: the existence of various uranium compounds in solution, isomorphic substitutions of all kinds, adsorption of uranium compounds and organic matter on the surfaces of submicron crystalline phosphate compounds. A decrease in the intensity of sorption factors leads to a decrease in the uranium content of phosphate. Under the oxidative conditions prevailed during the formation of Khoperian silicophosphorites, uranium has been sorbed by the phosphate only in negligible amounts (0.1x10/sup -4/%) due to the lack of organic colloids and uranium compounds capable of isomorphic substitution.

Final Report - Assessment of Potential Phosphate Ion-Cementitious Materials Interactions

International Nuclear Information System (INIS)

Naus, Dan J.; Mattus, Catherine H.; Dole, Leslie Robert

2007-01-01

The objectives of this limited study were to: (1) review the potential for degradation of cementitious materials due to exposure to high concentrations of phosphate ions; (2) provide an improved understanding of any significant factors that may lead to a requirement to establish exposure limits for concrete structures exposed to soils or ground waters containing high levels of phosphate ions; (3) recommend, as appropriate, whether a limitation on phosphate ion concentration in soils or ground water is required to avoid degradation of concrete structures; and (4) provide a 'primer' on factors that can affect the durability of concrete materials and structures in nuclear power plants. An assessment of the potential effects of phosphate ions on cementitious materials was made through a review of the literature, contacts with concrete research personnel, and conduct of a 'bench-scale' laboratory investigation. Results of these activities indicate that: no harmful interactions occur between phosphates and cementitious materials unless phosphates are present in the form of phosphoric acid; phosphates have been incorporated into concrete as set retarders, and phosphate cements have been used for infrastructure repair; no standards or guidelines exist pertaining to applications of reinforced concrete structures in high-phosphate environments; interactions of phosphate ions and cementitious materials has not been a concern of the research community; and laboratory results indicate similar performance of specimens cured in phosphate solutions and those cured in a calcium hydroxide solution after exposure periods of up to eighteen months. Relative to the 'primer,' a separate NUREG report has been prepared that provides a review of pertinent factors that can affect the durability of nuclear power plant reinforced concrete structures

Final Report - Assessment of Potential Phosphate Ion-Cementitious Materials Interactions

Energy Technology Data Exchange (ETDEWEB)

Naus, Dan J [ORNL; Mattus, Catherine H [ORNL; Dole, Leslie Robert [ORNL

2007-06-01

The objectives of this limited study were to: (1) review the potential for degradation of cementitious materials due to exposure to high concentrations of phosphate ions; (2) provide an improved understanding of any significant factors that may lead to a requirement to establish exposure limits for concrete structures exposed to soils or ground waters containing high levels of phosphate ions; (3) recommend, as appropriate, whether a limitation on phosphate ion concentration in soils or ground water is required to avoid degradation of concrete structures; and (4) provide a "primer" on factors that can affect the durability of concrete materials and structures in nuclear power plants. An assessment of the potential effects of phosphate ions on cementitious materials was made through a review of the literature, contacts with concrete research personnel, and conduct of a "bench-scale" laboratory investigation. Results of these activities indicate that: no harmful interactions occur between phosphates and cementitious materials unless phosphates are present in the form of phosphoric acid; phosphates have been incorporated into concrete as set retarders, and phosphate cements have been used for infrastructure repair; no standards or guidelines exist pertaining to applications of reinforced concrete structures in high-phosphate environments; interactions of phosphate ions and cementitious materials has not been a concern of the research community; and laboratory results indicate similar performance of specimens cured in phosphate solutions and those cured in a calcium hydroxide solution after exposure periods of up to eighteen months. Relative to the "primer," a separate NUREG report has been prepared that provides a review of pertinent factors that can affect the durability of nuclear power plant reinforced concrete structures.

Phosphate transporter mediated lipid accumulation in Saccharomyces cerevisiae under phosphate starvation conditions.

Science.gov (United States)

James, Antoni W; Nachiappan, Vasanthi

2014-01-01

In the current study, when phosphate transporters pho88 and pho86 were knocked out they resulted in significant accumulation (84% and 43%) of triacylglycerol (TAG) during phosphate starvation. However in the presence of phosphate, TAG accumulation was only around 45% in both pho88 and pho86 mutant cells. These observations were confirmed by radio-labeling, fluorescent microscope and RT-PCR studies. The TAG synthesizing genes encoding for acyltransferases namely LRO1 and DGA1 were up regulated. This is the first report for accumulation of TAG in pho88Δ and pho86Δ cells under phosphate starvation conditions. Copyright © 2013. Published by Elsevier Ltd.

Transformation of ceria nanoparticles in cucumber plants is influenced by phosphate

International Nuclear Information System (INIS)

Rui, Yukui; Zhang, Peng; Zhang, Yanbei; Ma, Yuhui; He, Xiao; Gui, Xin; Li, Yuanyuan; Zhang, Jing; Zheng, Lirong; Chu, Shengqi; Guo, Zhi; Chai, Zhifang; Zhao, Yuliang; Zhang, Zhiyong

2015-01-01

Transformation is a critical factor that affects the fate and toxicity of manufactured nanoparticles (NPs) in the environment and living organisms. This paper aims to investigate the effect of phosphate on the transformation of CeO 2 NPs in hydroponic plants. Cucumber seedlings were treated with 2000 mg/L CeO 2 NPs in nutrient solutions with or without adding phosphate (+P or –P) for 3 weeks. Large quantities of needle-like CePO 4 was found outside the epidermis in the +P group. While in the –P group, CePO 4 only existed in the intercellular spaces and vacuole of root cells. X-ray absorption near edge spectroscopy (XANES) indicates that content and percentage of Ce-carboxylates in the shoots of –P group (418 mg/kg, 67.5%) were much higher than those in the +P group (30.1 mg/kg, 21%). The results suggest that phosphate might influence the transformation process of CeO 2 NPs in plants and subsequently their ultimate fate in the ecosystem. - Highlights: • We compared the transformation of CeO 2 NPs in cucumber plants with and without phosphate in nutrient solutions. • Results of TEM and STXM show that CePO 4 located differently in roots between +P and –P group. • The chemical species distributions of Ce in shoots were different between +P and –P group by XANES. • Phosphate significantly affected the transformation of CeO 2 NPs in plants. - CeO 2 NPs can be partially transformed to CePO 4 and Ce carboxylates in hydroponic plants. Phosphate significantly affected the transformation of CeO 2 NPs and subsequent translocation of Ce species

Kinetic study of the thorium phosphate - diphosphate dissolution

International Nuclear Information System (INIS)

Dacheux, N.; Thomas, A.C.; Brandel, V.; Genet, M.

2000-01-01

The thorium phosphate-diphosphate Th 4 (PO 4 ) 4 P 2 O 7 (TPD) structure allows the replacement of large amounts of thorium by tetravalent actinides leading to the formation of solid solutions. This compound was obtained in powdered or sintered form after pressing at room temperature at 300-800 MPa then heating at 1250 deg. C for 10-30 hours. The resistance of this material to aqueous corrosion was determined by varying several parameters such as surface, leaching flow, acidity or temperature. It was thus possible to independently determine the influence of each parameter on the leaching rate provided that the saturation of the solution was not obtained. In acidic media, the partial order related to [H 3 O + ] was found to be in the 0.31-0.35 range while, in basic media, the partial order related to [OH - ] was almost the same (0.45). The activation energy (42 kJ/mol) was determined between 4 deg. C and 120 deg. C. Moreover, the addition of phosphate in the leachate slightly increased the TPD dissolution rate. When the saturation of the solution is reached, a gelatinous precipitate controls the thorium and phosphate concentrations. The complete characterization of this solid led to the proposed general formula Th 2 (PO 4 ) 2 (HPO 4 ). n H 2 O which conventional solubility product (at I = 0 M) is very low: K * S,0 10 -66.6±1.2 even in very acidic media. (authors)

21 CFR 137.175 - Phosphated flour.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Phosphated flour. 137.175 Section 137.175 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Related Products § 137.175 Phosphated flour. Phosphated flour, phosphated white flour, and phosphated...

Serum phosphate and cognitive function in older men.

Science.gov (United States)

Slinin, Yelena; Vo, Tien; Taylor, Brent C; Murray, Anne M; Schousboe, John; Langsetmo, Lisa; Ensrud, Kristine

2018-01-01

Determine whether serum phosphate is associated with concurrent cognitive impairment and subsequent cognitive decline in older men independent of demographic covariates and atherosclerotic risk factors. In a prospective study of 5529 men enrolled in the Osteoporotic Fractures in Men study, we measured baseline serum phosphate, baseline cognitive function, and change in cognitive function between baseline and follow-up exams an average of 4.6 years later using the Modified Mini-Mental State (3MS) Examination and Trails B. There was no association between serum phosphate and odds of cognitive impairment as assessed by baseline 3MS score or risk of cognitive decline as assessed by longitudinal change in 3MS score. Higher baseline serum phosphate was associated with higher odds of poor executive function as assessed by Trails B with fully adjusted odds ratios 1.12 (95% confidence interval: 0.83-1.52), 1.31 (0.97-1.77), and 1.45 (1.08-1.94) for men in the second, third, and fourth versus the bottom quartile (referent group) of serum phosphate (p-trend 0.007). However, higher phosphate level was not associated with risk of decline in executive function as assessed by longitudinal change in Trails B score with fully adjusted odds ratios 0.94 (95% confidence interval 0.69-1.28), 0.96 (0.70-1.32), and 1.21 (0.89-1.66) for men in the second, third, and fourth versus the bottom quartile (referent group) of serum phosphate (p-trend 0.22). Higher serum phosphate in older men was associated with a higher likelihood of poor executive function, but not with impaired global cognitive function or decline in executive or global cognition. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Third phase formation in the extraction of Th(NO_3)_4 by Tri-sec-butyl phosphate. A comparison with Tri-n-butyl phosphate

International Nuclear Information System (INIS)

Chandrasekar, Aditi; Suresh, A.; Sivaraman, N.

2017-01-01

Earlier studies carried out in our laboratory indicated that Tri-sec-butyl phosphate (TsBP) is a potential extractant for U/Th separation. Also, the third phase formation tendency of TsBP is lower compared to its isomers, Tri-n-butyl-phosphate (TBP) and Tri-iso-butyl phosphate (TiBP). In this context, the extraction and third phase formation behaviour of 1.1 M solutions of TiBP and TsBP in n-dodecane in the extraction of Th(IV) from 1 M HNO_3 at 303 K over a wide range of Th concentrations were investigated in the present study and the results are compared with the literature data on TBP system. Concentrations of Th(IV) and HNO_3 loaded in the organic phase before third phase formation (biphasic region) as well as in third phase and diluent-rich phase after third phase formation (triphasic region) were measured as a function of equilibrium aqueous phase Th(IV) concentration. The density of loaded organic phase was also measured at various Th(IV) concentrations. The extraction profiles in the biphasic region indicated that extraction of Th(IV) by TBP is higher than that of TiBP which in turn is higher than that of TsBP. Extractant concentration in the diluent-rich phase and third phase was measured for the triphasic region.

Studies of alkaline mediated phosphate migration in synthetic phosphoethanolamine l-glycero-d-manno-heptoside derivatives

International Nuclear Information System (INIS)

Stewart, A.; Martin, A.; Richards, J.C.; Bernlind, C.; Oscarson, S.; Schweda, E.K.H.

1998-01-01

Synthetic 2-, 3-, 4- and 6-monophosphate derivatives of methyl α-d-mannopyranosides, the 4-, 6- and 7-monophosphate derivatives of methyl l-glycero-α-d-manno-heptopyranosides and the corresponding phosphoethanolamine derivatives and a 6,7-cyclic phosphate analogue of methyl l-glycero-α-d-manno-heptopyranoside were used to study phosphate migration and hydrolysis when subjected to strong alkaline conditions (4 M KOH, 120 C, 18 h). The resulting products were analyzed by 1 H NMR spectroscopy and electrospray mass spectrometry. It was found that phosphate substituents were stable under these conditions and neither migration nor hydrolysis was observed except for the heptose 7-phosphate, which gave a substantial amount of phosphate hydrolysis. In phosphoethanolamine-substituted compounds migration to adjacent positions with concomitant loss of ethanolamine was found together with hydrolysis. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

The comparison of phosphate-titanate-silicate layers on the titanium and Ti6Al4V alloy base

Science.gov (United States)

Rokita, M.

2011-08-01

The studied layers were composed of two parts: titanate-silicate underlayer for better adhesion and titanate-phosphate-silicate layers for potential bioparameters. The layers with different amounts of hydroxyapatite were deposited on titanium and Ti6Al4V alloy substrates using dipping sol-gel method and electrophoresis. The selection of sol/suspension composition, deposition time and heat treatment conditions have the decisive influence on the layers parameters. The obtained layers should be very thin and almost amorphous. The specific nature of ceramic layers on the metal substrates excludes the use of some measurements methods or makes it difficult to interpret the measurement results. All the obtained samples were compared using XRD analysis data (GID technique), SEM with EDX measurements and FTIR spectroscopy (transmission and reflection techniques) before and after soaking in simulated body fluid. FTIR spectroscopy with mathematical treatment of the spectra (BIO-RAD Win-IR program, Arithmetic-subtract function) was used to detect the increase or decrease of any phosphate phases during SBF soaking. Based on the FTIR results the processes of hydroxyapatite (HAp) growth or layer dissolution were estimated. The layers deposited on titanium substrate are more crystalline then the ones deposited on Ti6Al4V. During SBF soaking process the growth of small amount of microcrystalline carbonate hydroxyapatite was observed on titanium substrate. The layer on Ti6Al4V base contained amorphous carbonate apatite. During heating treatment above about 870-920 K this apatite transforms into carbonate hydroxyapatite. The Ti6Al4V substrate seems to be more advantageous in context of potentially bioactive materials obtaining.

Evaluation of phosphate fertilizers for the immobilization of Cd in contaminated soils.

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Yin Yan

Full Text Available A laboratory investigation was conducted to evaluate the efficiency of four phosphate fertilizers, including diammonium phosphate (DAP, potassium phosphate monobasic (MPP, calcium superphosphateon (SSP, and calcium phosphate tribasic (TCP, in terms of the toxicity and bioavailability of Cd in contaminated soils. The efficiency of immobilization was evaluated on the basis of two criteria: (a the reduction of extractable Cd concentration below the TCLP regulatory level and (b the Cd changes associated with specific operational soil fractions on the basis of sequential extraction data. Results showed that after 50 d immobilization, the extractable concentrations of Cd in DAP, MPP, SSP, and TCP treated soils decreased from 42.64 mg/kg (in the control to 23.86, 21.86, 33.89, and 35.59 mg/kg, respectively, with immobilization efficiency in the order of MPP > DAP > SSP > TCP. Results from the assessment of Cd speciation via the sequential extraction procedure revealed that the soluble exchangeable fraction of Cd in soils treated with phosphate fertilizers, especially TCP, was considerably reduced. In addition, the reduction was correspondingly related to the increase in the more stable forms of Cd, that is, the metal bound to manganese oxides and the metal bound to crystalline iron oxides. Treatment efficiency increased as the phosphate dose (according to the molar ratio of PO4/Cd increased. Immobilization was the most effective under the molar ratio of PO4/Cd at 4:1.