Sample records for na2o cao k2o

  1. Multicomponent Diffusion in Silicate Melts: SiO2-TiO2-Al2O3-MgO-CaO-Na2O-K2O System

    NASA Astrophysics Data System (ADS)

    Guo, C.; Zhang, Y.

    2014-12-01

    Multicomponent diffusion in silicate melts is a very important process for mass transport in natural systems. It plays a large role in mixing and contamination of magmas, double-diffusive convection of magmas, and growth or dissolution of minerals in magma. The often-observed uphill diffusion profiles in natural systems and experiments require multicomponent diffusion treatment, but that has not been done. Instead, effective binary diffusion approximation has been widely used to treat chemical diffusion of components without uphill diffusion, even though it doesn't offer a consistent model for diffusion in a multicomponent system. In this report, we follow a long series of efforts in studying multicomponent diffusion in various melt systems (including SiO2-Al2O3-CaO, SiO2-Al2O3-MgO, SiO2-Al2O3-MgO-CaO, SiO2-Al2O3-Na2O-K2O-H2O and a basaltic melt). Chemical diffusion experiments in a haplobasaltic melt SiO2-TiO2-Al2O3-MgO-CaO-Na2O-K2O (50% SiO2, 1.5% TiO2, 15% Al2O3, 10% MgO, 19% CaO, 3% Na2O, 1.5% K2O) were conducted at 1500°C and 1 GPa. Nine successful experiments were carried out, of which 8 had initial compositions differing in only one independent component by 3 wt% (and compensated by SiO2). The concentration profiles in all 9 experiments were simultaneously fit using the Levenberg-Marquardt algorithm to obtain the 6 × 6 diffusion matrix. All features in the 7 concentration profiles of 9 experiments are well reproduced by the obtained diffusion matrix. More experiments will be carried out to further understand multicomponent diffusion, and we will use the diffusion matrix to simulate diffusion in natural systems.

  2. Characteristics and biocompatibility of Na 2O–K 2O–CaO–MgO–SrO–B 2O 3–P 2O 5 borophosphate glass fibers

    Microsoft Academic Search

    Kai Zheng; Shengbing Yang; Jiaojiao Wang; Christian R?ssel; Changsheng Liu; Wen Liang

    A novel Na2O–K2O–CaO–MgO–SrO–B2O3–P2O5 borophosphate glass fiber is prepared. The thermal properties including differential thermal analysis (DTA) and viscosity measurement of the glass were presented. The tensile strength of the glass fiber is measured. The reaction of the glass fibers in the SBF solution is characterized by XRD, FTIR and SEM. XRD and FTIR indicate that the carbonate hydroxyapatite has formed

  3. Synthesis of (Na2O,PbO)-Nb2O5, (Na2O,BaO)-Nb2O5, and (K2O,SrO)-Nb2O5 thin films using sol-gel method

    SciTech Connect

    Peng, Fei; Li, Dongsheng

    2010-09-01

    Homogeneous pore free Ba2NaNb5O15, KSr2Nb5O15, and 2•Na2O-PbO-6•Nb2O5 thin films were fabricated on sapphire substrates using the sol-gel technique. By controlling the gelation and coating process, thickness of thin films fabricated was controllable from ~40 nm to ~10 ?m. Synthesized thin films possessed highly preferred orientated microstructure. Another advantage of this method is the subsequent heat treatment temperature dramatically decreased compared with other methods. This increases stoichiometry control and makes the large scale fabrication more feasible and efficient.

  4. The effect of Er 3+ and Sm 3+ on phase separation and crystallization in Na 2O\\/K 2O\\/BaF 2\\/BaO\\/Al 2O 3\\/SiO 2 glasses

    Microsoft Academic Search

    Jordana Rocha Barros; Christian Bocker; Christian Rüssel

    2010-01-01

    Thermal annealing of Sm+3 or Er+3 doped Na2O\\/K2O\\/BaF2\\/BaO\\/Al2O3\\/SiO2 glasses led to the precipitation of nanocrystalline BaF2. The mean crystallite sizes were in the range from 9 to 15 nm as shown by XRD line broadening. Whereas glasses without rare earth oxides showed crystallites homogenously dispersed in the amorphous matrix, those doped with 0.05 mol% ErF3 or SmF3 showed highly agglomerated crystals. The

  5. Mixed Alkali Effect in (40-x)K2O-xLi2O-10Na2O-50B2O3 Glasses - Physical and Optical Absorption Studies

    NASA Astrophysics Data System (ADS)

    Samee, M. A.; Ahmmad, Shaikh Kareem; Taqiullah, Sair. Md.; Edukondalu, A.; Bale, Shashidhar; Rahman, Syed

    So far only a handful of publications have been concerned with the study of the mixed alkali effect in borate glasses containing three types of alkali ions. In the present work, the mixed alkali effect (MAE) has been investigated in the glass system (40-x) K2O-x Li2O -10Na2O-50B2O3.(0?x?40 mol%) through density and modulated DSC studies. The density and glass transition temperature of the present glasses varies non-linearly exhibiting mixed alkali effect. We report the mixed alkali effect in the present glasses through optical properties. From the absorption edge studies, the various values of optical band gap (Eo) and Urbach energy (?E) have been evaluated. The values of Eo and ?E show non-linear behavior with compositional parameter showing the mixed alkali effect. The band gap energy based average electronic polarizability of oxide ions ?O2-(Eo), optical basicity A(Eo), and Yamashita-Kurosawa’s interaction parameter A(Eo) have been examined to check the correlations among them and bonding character. Based on good correlation among electronic polarizability of oxide ions, optical basicity and interaction parameter, the present K2O- Li2O-Na2O-B2O3 glasses are classified as normal ionic (basic) oxides.

  6. EPR and optical absorption by Cu2+ ions in ZnO-Li2O-Na2O-K2O-B2O3 glasses

    NASA Astrophysics Data System (ADS)

    Hameed, Abdul; Ramadevudu, G.; Shareefuddin, Md.; Chary, M. Narasimha

    2014-04-01

    Electron Paramagnetic Resonance (EPR) studies at room temperature in the x-band frequencies on xZnO-10Li2O-10Na2O-10K2O-(69-x)B2O3-1CuO (x=0,2,4,6 and 8 mole%) glass systems were reported. The non-linear variation of spin-Hamiltonian parameters with ZnO content indicated the change in the ligand field strength around Cu2+ ions in the host glass. The ground state of Cu2+ ions in the glass is designated as dx2-y2 orbital (2B1g) while the observed symmetry around it is tetragonally distorted octahedral. The molecular orbital coefficients ?2, ?2 and ?12 are evaluated for Cu2+ doped samples. The non-linear variation in the values of parameters indicated mixed alkali effect in the glasses.

  7. The effect of Er 3+ and Sm 3+ on phase separation and crystallization in Na 2O/K 2O/BaF 2/BaO/Al 2O 3/SiO 2 glasses

    NASA Astrophysics Data System (ADS)

    Barros, Jordana Rocha; Bocker, Christian; Rüssel, Christian

    2010-12-01

    Thermal annealing of Sm +3 or Er +3 doped Na 2O/K 2O/BaF 2/BaO/Al 2O 3/SiO 2 glasses led to the precipitation of nanocrystalline BaF 2. The mean crystallite sizes were in the range from 9 to 15 nm as shown by XRD line broadening. Whereas glasses without rare earth oxides showed crystallites homogenously dispersed in the amorphous matrix, those doped with 0.05 mol% ErF 3 or SmF 3 showed highly agglomerated crystals. The latter was due to droplet phase separation in the rare earth doped glasses as proved by transmission electron microscopy while in the undoped glasses phase separation did not occur. Furthermore, the size of the droplets depended on the BaO-concentration. Fluorescence emission spectra of a samarium doped sample showed higher intensities than in the glasses they were prepared from.

  8. First Measurements of Time-Dependent Nucleation as a Function of Composition in Na2O.2CaO.3SiO2 Glasses

    NASA Technical Reports Server (NTRS)

    Kelton, K. F.; Narayan, K. Lakshmi

    1996-01-01

    The first measurements in any system of the composition dependence of the time-dependent nucleation rate are presented Nucleation rates of the stoichiometric crystalline phase, Na2O.2CaO.3SiO2, from quenched glasses made with different SiO2 concentrations were determined as a function of temperature and glass composition. A strong compositional dependence of the nucleation rates and a weak dependence for the induction times are observed. Using measured values of the liquidus temperatures and growth velocities as a function of glass composition, these data are shown to be consistent with predictions from the classical theory of nucleation, assuming a composition-dependent interfacial energy.

  9. The Meaning of High K2O Volcanism In the U.S. Cordillera

    NASA Astrophysics Data System (ADS)

    Putirka, K. D.; Busby, C.

    2010-12-01

    K2O contents provide a highly effective discriminant between volcanic rocks erupted in the Cascades and Basin-and Range-provinces, with Cascades volcanics having lower K2O contents at a given SiO2. To differentiate these suites, we use a K-index, where K-index = K2Oobserved - 0.12[SiO2] + 5.1 (oxides in wt. %). In the Sierra Nevada, regional K2O contents are not controlled by wall-rock assimilation. In addition, none are candidates for K-metasomatism, and none are likely to be derived by partial melting of a K-metasomatized source. As to the latter issue, even volcanic rocks with the highest K2O in the Sierra Nevada have K2O/Na2O <5, and most such ratios are <3. In contrast, K-metasomatized rocks have K2O/Na2O >5, and as high as 30-40 (Brooks and Snee (1996). Also, Sierra-wide K2O variations are not connected to indices of subduction-related mantle enrichments (such as La/Nb, Ba/Nb or Sr/P2O5), and so K2O is unconnected to regional variations in source composition. K2O contents are instead controlled by the degree of partial melting (F) in the mantle source and fractional crystallization. Putirka and Busby (2007) show that maximum K2O in the Sierra increases with increasing crust thickness, and this relationship also holds across the U.S. the Cordillera (at 39oN latitude). This relationship implies that low F magmas more easily transit thick, low-density upper crust (Putirka and Busby, 2007), which is a consequence of the fact that low F melts are enriched not just in K2O, but also in H2O, which greatly lowers magma density (Ochs and Lange, 1999). This model can explain the contrast in Cascade and Basin-and-Range K2O contents: the modern Cascades are built on the thinner crust of accreted terranes, while typical Basin-and-Range volcanics are erupted on older, and thicker, cratonized crust. Mean crust density, however, cannot be the only explanation of high K2O. In the central Sierra Nevada, the Colorado River Extensional Corridor, and at the Lunar Crater/Nevada Test site area of NV, eruptions of high K2O magmas (K-index>1.65) coincide in time and space with episodes of high extensional strain, as determined by field relationships. One possible explanation for this coincidence is provided by Takada (1994), who shows that under conditions of high differential stress, small, deep-seated dikes are less likely to coalesce; small degree partial melts contained in such are thus more likely to erupt. In summary, we conclude that mean crust density and differential stress are the two most important controls on K2O. The southern Sierra Nevada provides a good example; there, a very thick low-density granitoid batholith generally prohibits the eruption of basaltic magmas, unless the lithosphere experiences a high differential stress state, at which point small amounts of low density, low F melts are able to erupt. Pulses of high K-index volcanism are thus not monitors of discrete delamination events, but are indicators of extensional strain. In the Sierra Nevada, these pulses occur at 10-9 Ma and 3-3.5 Ma, perhaps signaling episodes of range uplift.

  10. Thermodynamics of Na 2 O-SiO 2 melts

    Microsoft Academic Search

    A. I. Zaitsev; N. E. Shelkova; B. M. Mogutnov

    2000-01-01

    The thermodynamic properties of Na2O-SiO2 solid (942-1285 K) and liquid (1103-1719 K, 19.5-61.8 mol % Na2O) silicates were studied by Knudsen cell mass spectrometry. To determine the activities of the constituent oxides, these\\u000a were reduced to volatile suboxides directly in effusion cells. Mass spectra of the saturated vapor over Na2O-SiO2 showed the presence of the Na+, Na2O+, NaO+, O\\u000a 2

  11. Liquidus Equilibria in the System K2O^Na2O^Al2O3^SiO2^F2O1^H2O

    E-print Network

    Long, Bernard

    fluorine-bearing granitic and rhyolitic magmas. Topaz and cryolite are stable saturating solid phases: granite; rhyolite; topaz; cryolite; magmatic differentiation I N T RODUC T ION In natural, fluorine. The rock sequence granite/rhyolite^topaz granite/ongonite^quartz topazite is characterized

  12. Nqrs Data for H4Na2O6W [Na2O4W·2(H2O)] (Subst. No. 2287)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume B 'Substances Containing C10H16 … Zn' of Volume 48 'Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains an extract of Section '3.2 Data tables' of the Chapter '3 Nuclear quadrupole resonance data' providing the NQRS data for H4Na2O6W [Na2O4W·2(H2O)] (Subst. No. 2287)

  13. Effects of Na2O on the Thermal Shock Resistance of Aluminosilicate Refractory Ceramics

    Microsoft Academic Search

    W. O. Soboyejo; E. T. Akpan; I. B. Bashir; J. Zimba; N. Hosannah; S. Allameh

    2007-01-01

    This report presents the results of an experimental study of the effects of Na2O on the thermal shock resistance (number of cold shock cycles to failure) of aluminosilicate refractory ceramics. The addition of 4–6% mole is shown to improve the thermal shock resistance, which is characterized by the number of shock cycles to failure. The Na2O changes the viscosity-temperature characteristics,

  14. Shear modulus, heat capacity, viscosity and structural relaxation time of Na 2 O–Al 2 O 3 –SiO 2 and Na 2 O–Fe 2 O 3 –Al 2 O 3 –SiO 2 melts

    Microsoft Academic Search

    Katarzyna Falenty; Sharon L. Webb

    2010-01-01

    The configurational heat capacity, shear modulus and shear viscosity of a series of Na2O–Fe2O3–Al2O3–SiO2 melts have been determined as a function of composition. A change in composition dependence of each of the physical properties\\u000a is observed as Na2O\\/(Na2O + Al2O3) is decreased, and the peralkaline melts become peraluminous and a new charge-balanced Al-structure appears in the melts.\\u000a Of special interest are the

  15. Heat treatment of Na2O-CaO-P2O5-SiO2 bioactive glasses: densification processes and postsintering bioactivity.

    PubMed

    Sola, A; Bellucci, D; Raucci, M G; Zeppetelli, S; Ambrosio, L; Cannillo, V

    2012-02-01

    Because of their excellent bioactivity, bioactive glasses are increasingly diffused to produce biomedical devices for bone prostheses, to face the dysfunctions that may be caused by traumatic events, diseases, or even natural aging. However, several processing routes, such as the production of scaffolds or the deposition of coatings, include a thermal treatment to apply or sinter the glass. The exposure to high temperature may induce a devetrification phenomenon, altering the properties and, in particular, the bioactivity of the glass. The present contribution offers an overview of the thermal behavior and properties of two glasses belonging to the Na2O-CaO-P2O5-SiO2 system, to be compared to the standard 45S5 Bioglass(®). The basic goal is to understand the effect of both the original composition and the thermal treatment on the performance of the sintered glasses. The new glasses, the one (BG_Na) with a high content of Na2O, the other (BG_Ca) with a high content of CaO, were fully characterized and sintering tests were performed to define the most interesting firing cycles. The sintered samples, treated at 880°C and 800°C respectively, were investigated from a microstructural point of view and their mechanical properties were compared to those of the bulk (not sintered) glass counterparts. The effect of sintering was especially striking on the BG_Ca material, whose Vickers hardness increased from 598.9 ± 46.7 HV to 1053.4 ± 35.0 HV. The in vitro tests confirmed the ability of the glasses, both in bulk and sintered form, of generating a hydroxyapatite surface layer when immersed in a simulated body fluid. More accurate biological tests performed on the sintered glasses proved the high bioactivity of the CaO-rich composition even after a heat treatment. PMID:22052581

  16. Boron Removal from Silicon by CaO-Na2O-SiO2 Ternary Slag

    NASA Astrophysics Data System (ADS)

    Safarian, Jafar; Tranell, Gabriella; Tangstad, Merete

    2015-06-01

    Boron removal from silicon is an important issue for solar-grade silicon feedstock production. In the present study, the removal of B from liquid silicon by a CaO-Na2O-SiO2 slag is studied and it is shown that B can be rapidly removed from silicon within short refining times. Based on mass balance and chemical analysis of the reacted silicon and slag, it is indicated that the kinetics of B removal is dependent on the Na2O in the slag, the main reactive agent for B removal from the system. The transported B into the slag is gasified at the slag-gas interface through sodium metaborate evaporation, which is a rate controlling reaction for B transport to the gas phase. It is indicated that B removal rate by CaO-Na2O-SiO2 slag is considerably higher than that by CaO-SiO2 slags. It is proposed that boron oxide (B2O3) is better embedded in the structure of CaO-SiO2 slags than Na2O-containing slags.

  17. Investigation of SiO2:Na2O ratio as a corrosion inhibitor for metal alloys

    NASA Astrophysics Data System (ADS)

    Mohamad, N.; Othman, N. K.; Jalar, A.

    2013-11-01

    The silicate is one of the potential compounds used as a corrosion inhibitor for metal alloys. The mixture between silica and sodium hydroxide (NaOH) succeeded to produce the silicate product. The formulation of a silicate product normally variable depended by the different ratio of SiO2:Na2O. This research utilized the agriculture waste product of paddy using its rice husk. In this study, the amorphous silica content in rice husk ash was used after rice husk burnt in a muffle furnace at a certain temperature. The X-ray diffraction (XRD) analysis was done to determine the existence of amorphous phase of silica in the rice husk ash. There are several studies that recognized rice husk as an alternative source that obtained high silica content. The X-ray fluorescence (XRF) analysis was carried out to clarify the percentage amount of Si and O elements, which referred the silica compound in rice husk ash. The preparation of sodium silicate formulation were differ based on the SiO2:Na2O ratio (SiO2:Na2O ratio = 1.00, 2.00 and 3.00). These silicate based corrosion inhibitors were tested on several testing samples, which were copper (99.9%), aluminum alloy (AA 6061) and carbon steel (SAE 1045). The purpose of this study is to determine the appropriate SiO2:Na2O ratio and understand how this SiO2:Na2O ratio can affect the corrosion rate of each metal alloys immersed in acidic medium. In order to investigate this study, weight loss test was conducted in 0.5 M hydrochloric acid (HCl) for 24 hours at room temperature.

  18. Study of Phase Separation in Na 2O–B 2O 3 Glass System by Nuclear Magnetic Resonance

    Microsoft Academic Search

    Wei-Fang Du; Koji Kuraoka; Tomoko Akai; Tetsuo Yazawa

    2000-01-01

    The 11B nuclear magnetic resonance (NMR) spectra, together with X-ray diffraction (XRD) and scanning electron microscopy (SEM), have been used to investigate the phase separation in 15Na2O–85B2O3 binary glass. Based on the present investigation we suggest that the phase equilibrium in sodium borate glasses is controlled by the rate competition of the nucleation and crystal growth between two immiscible phases

  19. The sulfur partition ratio and the sulfide capacity of Na2O-SiO2 slags at 1200 °C

    Microsoft Academic Search

    Allen H. Chan; R. J. Fruehan

    1986-01-01

    The sulfur partition ratio between carbon-saturated iron and Na2O-SiO2 slags and the sulfide capacity of these slags have been measured at 1200 °C. The two measurements are consistent with each other and the results are compared with other investigations. These slags have higher sulfide capacities and partition ratios than equivalent CaO-based slags and are thus attractive desulfurizers. Both the sulfide

  20. The sulfur partition ratio and the sulfide capacity of Na 2 O-SiO 2 slags at 1200 °C

    Microsoft Academic Search

    Allen H. Chan; R. J. Fruehan

    1986-01-01

    The sulfur partition ratio between carbon-saturated iron and Na2O-SiO2 slags and the sulfide capacity of these slags have been measured at 1200 ?C. The two measurements are consistent with each\\u000a other and the results are compared with other investigations. These slags have higher sulfide capacities and partition ratios\\u000a than equivalent CaO-based slags and are thus attractive desulfurizers. Both the sulfide

  1. Ion-Conducting Defect Pyrochlore Phases in the K 2 O–Sb 2 O 3 –WO 3 System

    Microsoft Academic Search

    V. A. Burmistrov; D. A. Zakhar'evich

    2003-01-01

    Potassium tungstate antimonates were prepared by calcining aK2CO3 + ßSb2O3 + 2(1 – a – ß)WO3 mixtures in air. Data on the phase composition of the obtained materials were used to locate the pyrochlore phase region in the Sb2Oz–W2O6 – K2O composition triangle at 1170 K. The distributions of the constituent ions and lattice defects over the crystallographic positions of

  2. The Influence of Na2O on the Solidification and Crystallization Behavior of CaO-SiO2-Al2O3-Based Mold Flux

    NASA Astrophysics Data System (ADS)

    Gao, Jinxing; Wen, Guanghua; Sun, Qihao; Tang, Ping; Liu, Qiang

    2015-05-01

    The reaction between [Al] and SiO2 sharply increased the Al2O3 and decreased SiO2 contents in mold flux during the continuous casting of high-Al steels. These changes converted original CaO-SiO2-based flux into CaO-SiO2-Al2O3-based flux, promoting the crystallization and deteriorating the mold lubrication. Therefore, study on the solidification and crystallization behavior of CaO-SiO2-Al2O3-based mold flux, with the applicable fluidizers, is of importance. The effect of Na2O, predominantly used as the fluidizer in mold flux, on the solidification and crystallization behavior of CaO-SiO2-Al2O3-based mold flux needs to be investigated. In this study, a CaO-SiO2-Al2O3-based mold flux containing 6.5 wt pct Li2O was designed; the effect of Na2O on the solidification and crystallization behavior of these mold fluxes was investigated using the single hot thermocouple technique (SHTT) and the double hot thermocouple technique (DHTT). Moreover, the slag film obtained by a heat flux simulator was analyzed using X-ray diffraction (XRD). The results indicate that the solid fraction of molten slag (Fs) and the crystalline fraction of solid slag (Fc) in the mold slag films decrease with increasing Na2O content from 0 to 2 wt pct. However, Fs and Fc increased when the Na2O content increased from 2 to 6 wt pct. The critical cooling rates initially decreases and then increases with increasing Na2O content. The XRD analysis results show that LiAlO2 and CaF2 were the basic crystals for all the mold fluxes. Increasing the Na2O content both inhibits the Ca2Al2SiO7 formation and promotes the production of Ca12Al14O33, indicating that the mold lubrication deteriorated because of the high melting-point phase formation of Ca2Al2SiO7 in the CaO-SiO2-Al2O3-based mold flux containing 6.5 wt pct Li2O, without Na2O. The strong crystallization tendency also deteriorated the mold lubrication for the mold flux with a higher Na2O content. Therefore, the addition of Na2O was less than 2 wt pct in the CaO-SiO2-Al2O3-based mold flux to suppress crystallization and enhance mold lubrication.

  3. Metamorphic evolution of eclogites at Qinglongshan: modeling in system Na2O-CaO-K2O-FeO-MgO-Al2O3-SiO2-H2O-TiO2-Fe2O3

    NASA Astrophysics Data System (ADS)

    Yan, R.; Yang, J.; Zhang, Z.

    2011-12-01

    Eclogite at Qinglongshan in NE Jiangsu province is one of the research objects which are investigated frequently and products are remarkable in ultra-high pressure (UHP) metamorphic petrology and geochemistry nearly twenty years. Though scholars in China and abroad have made abundant petrological work, there are opposite perspectives to some important petrological questions such as peak assemblage, crystalization time and condition of epidote porphyroblasts which contain coesite, peak assemblage contains talc or not, lawsonite has occurred in the rock or not. This paper choose eclogites in Qinglongshan. Besides traditional petrological work, we applied phase diagram modeling to mineral assemblage and chemical composition, quantitatively investigating the change with temperature and pressure. With the help of petrographic observation the petrological questiones can be solved. Eclogites in Qinglongshan can be divided into three categories: porphyroblastic foliated eclogites, granular massive eclogites and banded eclogites. The peak assemblage in three kinds of eclogites is garnet + omphacite + phengite + kyanite +rutile + coesite. The minerals in the peak assemblage show shape preferred orientation defining the rock foliation in porphyroblastic eclogites. The peak assemblage defined by garnet compositional isopleths in the calculated phase diagram is garnet +omphacite + phengite + kyanite + rutile + coesite + lawsonite + talc in porphyroblastic eclogites, and is garnet + omphacite + phengite + kyanite + rutile +coesite + lawsonite in banded eclogites, both inconsistent with the petrographic observation. This discrepancy probably resulted from the assumption of pure water as the ultrahigh-pressure (UHP) fluid phase. Three stages of metamorphism are established for Qinglongshan eclogites. Prograde inclusions such as amphibole, epidote, plagioclase, chlorite, muscovite, paragonite and albite coexist in the area of < 0.8GPa and < 575. It can infer from mineral assemblage that peak temperature and pressure are higher than 710 and 2.9GPa in porphyroblastic eclogites and >620 and 2.9GPa in banded eclogites. Both petrography and phase diagram modelling demonstrate a crystallization sequence of kyanite-epidote-talc, with the first two having begun to crystallize at UHP condition and hence including coesite. The mode of epidote increases dramatically at < 2 GPa resulting in the formation of large porphyroblasts. The randomly oriented porphyroblasts overprint the rock foliation, implying that they crystallized later than the peak assemblage under a weak shear stress field. Kyanite begun to crystallize at early retrogression in banded eclogites. Epidote begun to develop at low pressure, so there is no coesite in banded eclogites. Symplectite is the product of late retrograde metamorphism. The P-T paths of porphyroblastic eclogites and banded eclogites defined by the mineral assemblages are both typically the hair-pin type. The amounts of hydrous minerals increased during retrogression, implying continuous ingress of fluids into the rock.

  4. Phase equilibria in the oxide system Nd 2O 3–K 2O–P 2O 5

    Microsoft Academic Search

    Irena Szczygiel; Teresa Znamierowska; Dagmara Mizer

    2010-01-01

    A phase equilibria diagram of the partial system NdPO4–K3PO4–KPO3 has been developed as part of the research aimed at determining the phase equilibrium relationships in the oxide system Nd2O3–K2O–P2O5. The investigations were conducted using thermoanalytical techniques, X-ray powder diffraction analysis and reflected-light microscopy. Three isopleths existing between: K3Nd(PO4)2–K4P2O7, NdPO4–K5P3O10 and NdPO4–K4P2O7 have been identified in the partial NdPO4–K3PO4–KPO3 system. Previously

  5. Phosphorus distribution between carbon-saturated iron at 1350 °C and lime-based slags containing Na 2 O and CaF 2

    Microsoft Academic Search

    W. H. Van Niekerk; R. J. Dippenaar

    1998-01-01

    The Corex process is capable of consistently producing hot metal with very low silicon contents (<0.1 pct), and as a consequence,\\u000a its hot metal is ideally suited for the external removal of phosphorus. Various studies have shown that small additions of\\u000a Na2O significantly enhance the ability of lime-based slags to dephosphorize liquid iron. Additions of fluxes (such as CaF2) may

  6. Effect of the SiO 2\\/Na 2O ratio on the alkali activation of fly ash. Part II: 29Si MAS-NMR Survey

    Microsoft Academic Search

    M. Criado; A. Fernández-Jiménez; A. Palomo; I. Sobrados; J. Sanz

    2008-01-01

    29Si MAS-NMR spectroscopy was used to characterize the reaction products resulting from the alkali activation of a type F fly ash. Specifically, analyses focused on the degree of polymerization of the activating solution (SiO2\\/Na2O ratio=0.0, 0.19, 0.69 and 1.17) and thermal curing time (from 8h to 180 days at 85°C). The results obtained showed that the degree of polymerization of

  7. Ionic conductivity of alkaline (Li 2O, Na 2O) and alkaline-earth (BaO) borates in crystallization (vitrification) region

    NASA Astrophysics Data System (ADS)

    Solntsev, V. P.; Davydov, A. V.

    2011-11-01

    In this paper we report the existence of abnormal behavior of electric properties of alkaline (Li 2O,Na 2O) and alkaline-earth (BaO) borate in the melt—a crystal (glass) transition region. Results of measurement of conductivity in the mentioned interval evidence the existence of a strong variation of electric properties depending on the concentration of alkaline and alkaline-earth ions. The reasons of such behavior are discussed.

  8. Radiation-induced color centers in ?-irradiated glasses in the Na 2 O-Nb 2 O 5 -P 2 O 5 system

    Microsoft Academic Search

    E. V. Avdeeva; T. V. Bocharova; G. O. Karapetyan; A. M. Mironov

    2006-01-01

    The specific features of the induced optical absorption spectra of glasses in the 45Na2O xNb2O5 (55 ? x)P2O5 system with Nb2O5 contents x = 5, 10, 20, 25, 30, and 35 mol % are investigated as functions of the irradiation dose and the heat treatment time. The\\u000a spectra are decomposed into Gaussian components with the use of computer processing. It

  9. Medium-term phase stability of Na 2O–Al 2O 3–SiO 2–H 2O geopolymer systems

    Microsoft Academic Search

    Pre De Silva; Kwesi Sagoe-Crenstil

    2008-01-01

    The phase evolution and microstructural development of a series of geopolymer mixtures comprising SiO2, Al2O3, Na2O and H2O prepared by alkali reaction of metakaolin, have been studied. The study also included the effects of cure duration and its impact on physical properties such as compressive strength. The characteristic molar ratios of the geopolymer mixtures were of the range SiO2\\/Al2O3 [2.50–5.01

  10. Spectral analysis of RE 3+ (RE = Sm, Dy, and Tm): P 2O 5–Al 2O 3–Na 2O glasses

    Microsoft Academic Search

    G. Lakshminarayana; Rong Yang; Mengfei Mao; Jianrong Qiu

    2009-01-01

    Phosphate glasses in the compositions of 70P2O5–15Al2O3–14Na2O–1RE3+ (RE=Sm, Dy, and Tm) (mol%) were prepared by melt-quenching technique and characterized optically. The differential thermal analysis (DTA) profile of the host glass was carried out to confirm its thermal stability. For all the glasses absorption, photoluminescence and decay measurements have also been carried out. These glasses have shown strong emission and absorption

  11. Sol–gel processed TiO 2–K 2O–LiZnVO 4 ceramic thin films as innovative humidity sensors

    Microsoft Academic Search

    Jierong Ying; Chunrong Wan; Peijiong He

    2000-01-01

    Active elements for humidity sensors based on TiO2–K2O–LiZnVO4 ceramic thin films have been prepared by the sol–gel technique. The films heated to 600°C, whose composition is Ti:K:Li:Zn:V:O=1:0.04:0.1:0.1:0.1:2.42 (molar ratios), are composed of semiconductor ceramics (rutile TiO2), alkali metal oxide (K2O) and glass (LiZnVO4). At the frequency of 40 Hz, the elements' impedance (Zp), resistance (Rp) and capacitance (Cp) vs. relative

  12. Effect of Al 2O 3 and K 2O content on structure, properties and devitrification of glasses in the Li 2O–SiO 2 system

    Microsoft Academic Search

    Hugo R. Fernandes; Dilshat U. Tulyaganov; Ashutosh Goel; Manuel J. Ribeiro; Maria J. Pascual; José M. F. Ferreira

    2010-01-01

    The effect of Al2O3 and K2O content on structure, sintering and devitrification behaviour of glasses in the Li2O–SiO2 system along with the properties of the resultant glass–ceramics (GCs) was investigated. Glasses containing Al2O3 and K2O and featuring SiO2\\/Li2O molar ratios (3.13–4.88) far beyond that of lithium disilicate (Li2Si2O5) stoichiometry were produced by conventional melt-quenching technique along with a bicomponent glass

  13. Physical, optical and structural properties of xNa2O-(50-x)Bi2O3-10ZnO-40B2O3 glasses

    NASA Astrophysics Data System (ADS)

    Dahiya, Sajjan; Maan, A. S.; Punia, R.; Kundu, R. S.; Murugavel, S.

    2013-02-01

    Glasses with composition xNa2O-(50-x)Bi2O3-10ZnO-40B2O3 with 0 ? x? 20 have been synthesized by conventional melt quench method. Density and molar volume decreases with increase in Na2O content. The optical absorption studies revealed that the cutoff wavelength decreases and optical band gap (Eopt) increases with increase in Na2O content and the present glass system shows indirect allowed transitions. The IR studies indicate that these glasses are made up of [BiO3] [BiO6], [BO3] and [BO4] basic structural units. Na2O acts a network modifier and modify the glass structure.

  14. Investigation of thermal and spectroscopic properties of Bi2O3-GeO2-Ga2O3-Na2O glasses doped with Er3+ ions

    NASA Astrophysics Data System (ADS)

    Ragin, Tomasz; Czajkowski, Karol; ?mojda, Jacek; Kochanowicz, Marcin; Dorosz, Dominik

    2014-11-01

    Heavy metal oxide glasses based on the Bi2O3-GeO2-Ga2O3-Na2O system doped with Er3+ ions have been presented.. The influence of glass composition on thermal stability and luminescent properties has been presented. Fabricated glass exhibits emission at 1538 nm (Er3+: 4I13/2 --> 4I15/2) under 980 nm laser diode excitation. Due to different molar content of oxides in samples, various luminescence intensity was observed. High absorption cross-section allowed to determine the gain coefficient at the level of 3.47 cm-1 at the wavelength of 1538 nm. According to the results, fabricated bismuthgermanate glasses should be used for construction of optical waveguides operating in the range of near-infrared.

  15. Upconversion fluorescence spectroscopy of Er3+/Yb3+-doped heavy metal Bi2O3-Na2O-Nb2O5-GeO2 glass

    NASA Astrophysics Data System (ADS)

    Oliveira, A. S.; de Araujo, M. T.; Gouveia-Neto, A. S.; Sombra, A. S. B.; Medeiros Neto, J. A.; Aranha, N.

    1998-01-01

    Upconversion fluorescence emission of Er3+/Yb3+-doped Bi2O3-Na2O-Nb2O5-GeO2 heavy metal glass samples excited at 1.06 ?m is experimentally investigated. The results reveal the existence of intense emission bands centered around 520, 545, and 655 nm. The germano-niobate based host glass presents high transparency in the region of 400-2700 nm, the capability of incorporating high dopant concentrations, high melting temperature, and large resistance to atmospheric moisture. The observed intensity of the green fluorescence emission, suggested that the niobium based host glass material plays an important role in the efficiency of the upconversion process. Emission lines centered at 425, 483, 503, 608, and 628 nm were also observed.

  16. Gels and gel-derived glasses in the system Na2O-B2O3-SiO2

    NASA Technical Reports Server (NTRS)

    Mukherjee, S. P.

    1983-01-01

    The containerless melting of high-purity multicomponent homogeneous gels and gel monoliths offers a unique approach to making ultrapure multicomponent optical glasses in the reduced gravity environment of space. Procedures for preparing and characterizing gels and gel-derived glasses in the system Na2O-B2O3-SiO2 are described. Preparation is based on the polymerization reactions of alkoxysilane with trimethyl borate or boric acid and a suitable sodium compound. The chemistry of the gelling process is discussed in terms of process parameters and the gel compositions. The physicochemical nature of gels prepared by three different procedures was found to be significantly different. Infrared absorption spectra indicate finite differences in the molecular structures of the different gels. The melting of the gel powders and the transformation of porous gel monoliths to transparent 'glass' without melting are described.

  17. Gels and gel-derived glasses in the Na2O-B2O3-SiO2 system. [containerless melting in space

    NASA Technical Reports Server (NTRS)

    Mukherjee, S. P.

    1982-01-01

    The containerless melting of high-purity multicomponent homogeneous gels and gel-monoliths offers a unique approach to making ultrapure multicomponent optical glasses in the reduced gravity environment of space. Procedures for preparing and characterizing gels and gel-derived glasses in the Na2O-B2O3-SiO2 system are described. Preparation is based on the polymerization reactions of alkoxysilane with trimethyl borate or boric acid and a suitable sodium compound. The chemistry of the gelling process is discussed in terms of process parameters and the gel compositions. The physicochemical nature of gels prepared by three different procedures were found to be significantly different. IR absorption spectra indicate finite differences in the molecular structures of the different gels. The melting of the gel powders and the transformation of porous gel-monoliths to transparent 'glass' without melting are described.

  18. Structural variation in gamma ray irradiated PbO-Na2O-B2O3-SiO2 glasses

    NASA Astrophysics Data System (ADS)

    Kaur, Ravneet; Singh, Surinder; Pandey, O. P.

    2014-06-01

    Glasses with compositions xPbO-15Na2O-(70-x) B2O3-15SiO2 where x=5, 10, 15, 20 and 25 (mol%) have been prepared using the melt quenching technique. The structural properties of these glasses have been investigated using the FTIR spectroscopy. The effect of the presence of modifier PbO on the glass system is also studied. The FT-IR spectral investigation of these glasses exhibits characteristic vibrations of BO4 and BO3 units together with SiO4 as well as PbOn (n=4,6) groups. The gamma ray interaction of the present glass system in the dose range 0.1-60 kGy is investigated. The results indicate that gamma rays result in the structural rearrangements in glass affecting the bridging and non bridging oxygens.

  19. Synthesis and properties of lithium disilicate glass-ceramics in the system SiO 2–Al 2O 3–K 2O–Li 2O

    Microsoft Academic Search

    D. U. Tulyaganov; S. Agathopoulos; I. Kansal; P. Valério; M. J. Ribeiro; J. M. F. Ferreira

    2009-01-01

    The purpose of this study was the synthesis of lithium disilicate glass-ceramics in the system SiO2–Al2O3–K2O–Li2O. A total of 8 compositions from three series were prepared. The starting glass compositions 1 and 2 were selected in the leucite–lithium disilicate system with leucite\\/lithium disilicate weight ratio of 50\\/50 and 25\\/75, respectively. Then, production of lithium disilicate glass-ceramics was attempted via solid-state

  20. Role of B2O3 on the Viscosity and Structure in the CaO-Al2O3-Na2O-Based System

    NASA Astrophysics Data System (ADS)

    Kim, Gi Hyun; Sohn, Il

    2013-10-01

    The effect of B2O3 on the viscosity and structure in the calcium-aluminate melt flux system containing Na2O was studied. An increase in the B2O3 content at fixed CaO/Al2O3 ratio lowered the viscosity. Higher CaO/Al2O3 ratio at fixed B2O3 content also decreased the viscosity. The alumino-borate structures were confirmed through Fourier transformed infrared (FTIR) and Raman spectroscopy and consisted of [AlO4]-tetrahedral structural units, [BO3]-triangular structural units, and [BO4]-tetrahedral structural units, which could be correlated to the viscosity. At fixed CaO/Al2O3 ratio, B2O3 additions decreased the [AlO4]-tetrahedral structural units and transformed the 3-D network structures such as pentaborate and tetraborate into 2-D network structures of boroxol and boroxyl rings by breaking the bridged oxygen atoms (O0) to produce non-bridged oxygen atoms (O-) leading to a decrease in the molten flux viscosity. At fixed B2O3 contents and higher CaO/Al2O3 ratio, 3-D complex network structures become 3-D simple and 2-D isolated network structures, resulting in lower viscosities. The apparent activation energy for viscous flow varied from 132 to 249 kJ/mol according to the composition of B2O3 and CaO/Al2O3 ratio.

  1. Phosphorus and boron speciation in K 2O-B 2O 3-SiO 2-P 2O 5 glasses

    NASA Astrophysics Data System (ADS)

    Gan, Hao; Hess, Paul C.; Kirkpatrick, R. James

    1994-11-01

    Raman, 11B and 31P MAS NMR spectra of yP2O5 · (1 - y) [(20 - x)% K2O · x% B2O3 · 80% SiO2] glasses ( y = 0 to 0.03 and x = 5 to 13) show that dimers (P 1) and chains (P 2) are the dominant structural units for phosphate species; six-member rings (3B and 3O) and SiOB(IV) bonds are the major bonding types for boron-bearing species. Some of the B(IV)'s in the silicate network may be in structural sites similar to danburite. The coordination of B is strongly controlled by P in the glasses. The relative proportion of B(IV) to total B decreases significantly after adding less than 3 mol% P 2O 5. Homogeneous equilibria are determined from the spectral data to generalize the observed structural changes for each group of glasses with a fixed K 2O /B 2O 3 ratio. The DELL and BRAY (1983) model for B coordination is partially revised to meet the new data of B speciation derived from 11B MAS NMR spectra.

  2. doi:10.1016/j.gca.2005.07.006 Thermodynamic modeling of melts in the system Na2O-NaAlO2-SiO2-F2O 1

    E-print Network

    Long, Bernard

    doi:10.1016/j.gca.2005.07.006 Thermodynamic modeling of melts in the system Na2O-NaAlO2-SiO2-F2O 1) Abstract--Fluorine is a common volatile element in magmatic-hydrothermal systems, but its solution equilibria and spectroscopic information on melt structure. The model is applicable to crystallization

  3. Influence of CaF2 and Li2O on the Viscous Behavior of Calcium Silicate Melts Containing 12 wt pct Na2O

    NASA Astrophysics Data System (ADS)

    Park, Hyun Shik; Kim, Hyuk; Sohn, Il

    2011-04-01

    Understanding the viscous behavior of silica-based molten fluxes is essential in maintaining the reliability of steel casting operations and in preventing breakouts. In particular, high concentrations of aluminum in recently developed transformation induced plasticity (TRIP) and twinning induced plasticity (TWIP) steels tend to promote reduction of silica in the mold fluxes that result in the formation of alumina, which in turn increases the viscosity. To counteract this effect, significant amounts of fluidizers such as CaF2 and Li2O are required to ensure that mold fluxes have acceptable lubrication and heat transfer characteristics. The viscous behavior of the slag system based on CaO-SiO2-12 wt pct Na2O with various concentrations of CaF2 and Li2O has been studied using the rotating spindle method to understand the effects on the viscosity with these additives. CaF2 additions up to 8 wt pct were effective in decreasing the viscosity by breaking the network structure of molten fluxes, but CaF2 concentrations above this level had a negligible effect on viscosity. Li2O additions up to 2 wt pct were also effective in decreasing the viscosity, but the effect was comparatively negligible above 2 wt pct. Using Fourier transform infrared (FTIR) analysis of as-quenched slag samples, it was concluded that the viscosity was controlled more effectively by changing the larger complex silicate structures of rings and chains than by changing the amounts of simpler dimers and monomers.

  4. In vitro bioactivity evaluation, mechanical properties and microstructural characterization of Na2O-CaO-B2O3-P2O5 glasses

    NASA Astrophysics Data System (ADS)

    Abo-Naf, Sherief M.; Khalil, El-Sayed M.; El-Sayed, El-Sayed M.; Zayed, Hamdia A.; Youness, Rasha A.

    2015-06-01

    Na2O-CaO-B2O3-P2O5 glasses have been prepared by the melt-quenching method. B2O3 content was systematically increased from 5 to 30 mol%, at the expense of P2O5, in the chemical composition of these glasses. Density, Vickers microhardness and fracture toughness of the prepared glasses were measured. In vitro bioactivity of the glasses was assessed by soaking in the simulated body fluid (SBF) at 37 ± 0.5 °C for 3, 7, 14 and 30 days. The glasses were tested in the form of glass grains as well as bulk slabs. The structure and composition of the solid reaction products were analyzed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). The kinetics of degradation of the glass particles were monitored by measuring the weight loss of the particles and the ionic concentration of Ca, P and B in the SBF solution using inductive coupled plasma-atomic emission spectroscopy (ICP-AES). The obtained results revealed the formation of a bioactive hydroxyapatite (HA) layer, composed of nano-crystallites, on the surface of glass grains after the in vitro assays. The results have been used to understand the formation of HA as a function of glass composition and soaking time in the SBF. It can be pointed out that increasing B2O3 content in glass composition enhances the bioactivity of glasses. The nanometric particle size of the formed HA and in vitro bioactivity of the studied glasses make them possible candidates for tissue engineering application.

  5. Visible absorption structure of chromium doped (80-x)Sb2O3-20K2O-xPbO glasses

    NASA Astrophysics Data System (ADS)

    Petkova, P.; Ghamri, A.; Vasilev, P.; Ismailov, I.; Soltani, M. T.

    2014-09-01

    Chromium doped glasses in the (80-x)Sb2O3-20K2O-xPbO:Cr system (x = 10–30 mol. %) have been investigated by absorption spectra in the 1–2,2 eV (8065–17 730 cm?1) spectral range. The synthesis of glasses has been carried out by using the melt-quenching method. The observed absorption band is due to the Cr-impurity in the visible spectral region. The absorption bands of glasses do not contain information about the exact energy position of the Cr levels. Therefore, we have calculated the second derivative of absorption curves. It is established that Cr3+ and Cr4+ ions are surrounded by distorted octahedral coordination in the investigated glasses. The energy level structure of the Cr3+ and Cr4+ ions in the samples are also presented. The crystal field parameter Dq and the Racah parameters B and C have been calculated.

  6. Optical absorption and emission of Ni-doped (80-x)Sb2O3-20K2O-xMoO3 glasses

    NASA Astrophysics Data System (ADS)

    Petkova, P.; Houhou, S.; Soltani, M. T.

    2013-11-01

    New antimony oxide glasses were synthesized by the conventional method in the ternary system (80-x)Sb2O3-20K2O-xMoO3 (x = 30 and 40 mol%) doped with 0.1 mol% of NiO. The optical absorption spectra of Ni-doped glasses in the spectral range 750-900 nm consist of two maxima around 780 and 850 nm that are related to Ni2+ in the octahedral environment. The maxima intensity decreases with increasing Sb2O3 and decreasing MoO3. The Condon-Shortley parameters F0, F2 and F4 have been used to determine the crystal field parameters of Ni2+ in these glasses. Racah's parameters have also been calculated. Visible emission at 560 nm has been obtained at room temperature.

  7. The effect of TiO 2 on phase separation and crystallization of glass-ceramics in CaO–MgO–Al 2O 3–SiO 2–Na 2O system

    Microsoft Academic Search

    Mingsheng Ma; Wen Ni; Yali Wang; Zhongjie Wang; Fengmei Liu

    2008-01-01

    The experiments were carried out on studying the effect of phase separation on nucleation and crystallization in the glass based on the system of CaO–MgO–Al2O3–SiO2–Na2O. In the experiments, TiO2 was chosen as nucleating agent. Three batches of 5, 8 and 10wt% TiO2 substitution were investigated by the techniques of DSC, XRD, FTIR and FESEM equipped with EDS. XRD and FTIR

  8. Rheology and Structure of Chlorine, Fluorine and Water-Bearing Na2O-CaO-Al2O3-SiO2 Melts

    NASA Astrophysics Data System (ADS)

    Baasner, A.; Schmidt, B.; Webb, S. L.; Dupree, R.

    2012-12-01

    The effect of chlorine (Cl), fluorine (F) and water (H2O), alone and in combination, on the rheology and structure of synthetic peralkaline Na2O-CaO-Al2O3-SiO2 melts as an analog for highly evolved alkaline melts is investigated. We also investigated a peraluminous counterpart to study how the effect of Cl and F depends on the (Na+Ca)/Al ratio. The volatile-free melts were produced from oxide and carbonate powders at 1 atm and temperatures between 1200 and 1650 °C. Amounts of 0.5 to 1.3 mol% of Cl and 0.5 to 18 mol% F were added as NH4Cl, NH4F, NaCl, NaF, CaCl2 and CaF2. The composition of the samples was analysed by electron microprobe. The melts were hydrated with 0.5 to 4 wt% H2O. For the hydration of the peralkaline melts we used an internally heated pressure vessel at 1200 to 1250 °C and 1.5 to 3 kbar. Because of their high liquidus temperatures, the peraluminous melts were hydrated at 1600 to 1675°C and 5 kbar in a piston cylinder apparatus. Water contents were determined by Karl-Fischer-titration, thermogravimetry and IR-spectroscopy. The viscosities of the dry and hydrous peralkaline and peraluminous melts were measured with micropenetration and parallel plate techniques between 13 log10(Pa s) and 5.5 log10(Pa s). We found that the addition of 1.1 mol% Cl to peralkaline melts increased the viscosity by 0.8 log10(Pa s) while 1.9 mol% F decreased the viscosity by 1.2 log10(Pa s) relative to a viscosity of 12 log10(Pa s) of the halogen-free melt. In peralkaline melts containing equal amounts of both, Cl and F, the viscosity is 0.5 log10(Pa s) lower than the volatile-free melt, independent of the total amount of halogens. The effects of Cl and F seem to buffer each other. If there is twice as much F in the melt as Cl, the viscosity is reduced by 0.7 log10(Pa s). In peraluminous melts containing Cl and F the viscosity decreases with increasing volatile content independent of the ratio between the two volatiles. The addition of H2O decreases the viscosity of the peralkaline halogen-free melt by 3.4 log10(Pa s) at ~0.5 wt% H2O and 9.2 log10(Pa s) at ~4 wt% H2O. In both melts F and Cl seem to have no strong influence on the viscosity lowering effect of H2O. The local glass structure was investigated with 19F and 35Cl MAS NMR. Our data show that the F environment has at least 4 sites in the peralkaline melts, more than in the peraluminous melts, where there are 2 different sites. In the peralkaline melts there is a speciation change of F depending on the total amount of F. Cl is located in "salt-like" mixed Ca and Na environments in the peralkaline and peraluminous melts. As the Ca/(Na+Ca) ratio is ~0.16, Na is more prominent in the mixed sites. However, compared to the peralkaline melts Ca becomes slightly more important in the Cl-environment in the peraluminous melts.

  9. Coupled Market Behavior Based Financial Crisis Detection Wei Cao, Longbing Cao and Yin Song

    E-print Network

    Cao, Longbing

    Coupled Market Behavior Based Financial Crisis Detection Wei Cao, Longbing Cao and Yin Song Abstract-- Financial crisis detection is a long-standing chal- lenging issue with significant practical, in particular, the nonlinear and dynamic characteristics associated with financial crisis. Most of existing

  10. Mineralogy, major and trace element geochemistry of riverbed sediments in the headwaters of the Yangtze, Tongtian River and Jinsha River

    Microsoft Academic Search

    Weihua Wu; Shijun Xu; Huayu Lu; Jiedong Yang; Hongwei Yin; Wen Liu

    2011-01-01

    We collected riverbed sediments of the headwaters of the Yangtze River (Chumaer River, Tuotuo River, Gaerqu River and Buqu River), Tongtian River and Jinsha River (HTJR) flowing on the eastern Tibetan Plateau and analyzed their mineralogical features, major and trace element contents. The results show: (i) very poor correlations of Na2O, K2O, CaO, Ba, and Sr to SiO2, LREE to

  11. Structural and optical properties of 60B2O3-(20-x)Na2O-10PbO-10Al2O3:xTiO2:yNd2O3 glasses

    NASA Astrophysics Data System (ADS)

    de Souza, N. C. A.; Santos, C. C.; Guedes, I.; Dantas, N. O.; Vermelho, M. V. D.

    2013-10-01

    In this work we investigate the effect of replacing Na2O by TiO2 on the structural and spectroscopic characteristics of the Nd2O3-doped 60B2O3-(20-x)Na2O-10PbO-10Al2O3:xTiO2:yNd2O3 borate glass matrix. Measurements of X-ray patterns, glass temperatures (Tg), vibrational (Raman and infrared (IR)) and optical (absorption and emission) spectra were carried out. The trend of Tg, the Judd-Ofelt parameters and Nephelauxetic ratio as the TiO2 and Nd2O3 concentration increases was interpreted quantitatively and qualitatively in terms of the network bonds and coordination numbers. Measurements of Tg across the Nd-doped glass series for different levels of Ti suggests changes in the rigidity of the matrix due to change of coordination of boron oxide resulting from the BO4-BO3 back conversion effect. The changes observed in the Raman and IR spectra are related to the BO3 ? BO4 conversion effect. The variation of the Judd-Ofelt parameters ? and ? indicates that the average rare earth-ligand radius decreases establishing an electronic density distribution when Nd3+ concentration increases. This effect is interpreted in terms of Judd-Ofelt parameters and by the bonding parameter b due to Nephelauxetic effect.

  12. CSE 513: Distributed Systems Instructor: Guohong Cao

    E-print Network

    Cao, Guohong

    CSE 513: Distributed Systems Instructor: Guohong Cao OÆce, Phone, Email: 310 pond lab, 863 Systems, M. Singhal and N. Shivaratri References: Distributed Systems Concepts and Design, G. Coulouris, J. Course Outline: 1. Architectures of Distributed Systems { System models, networking and inter

  13. LA TEORÍA DEL CAOS EN LA ECONOMÍA

    Microsoft Academic Search

    Fredy H. Wompner G

    2008-01-01

    En el presente trabajo se examinan los conceptos generales al uso sobre el caos. Se catalogan los conceptos clave que pueden ser útiles y que históricamente han conformado una teoría del desorden y su situación actual en diversas publicaciones. Se analiza desde su historia, evolución, principios e implicancias en otras disciplinas como en la economía. En esta dirección se realiza

  14. Ruptura y caos en Timeball de Joel Cano

    E-print Network

    Seda, Laurietz

    1996-10-01

    conceptos del margen, del centro y del 6 LATIN AMERICAN THEATRE REVIEW tiempo. Mediante las ideas básicas que propone la teoría del caos se demuestra aquí cómo esta obra rechaza toda estructura tradicional de orden, tiempo y forma a la misma vez que... pueblo cubano). Puede decirse que la teoría del caos es relativamente nueva. Sin embargo, el caos como tal siempre ha existido. El concepto del caos nace en el siglo XIX cuando Henry Poincaré (al que muchas personas consideran el padre del caos) se...

  15. Investigation of phase equilibria in the system Nd 2O 3–Na 2O–P 2O 5. The partial system NdPO 4–Na 4P 2O 7–NaPO 3

    Microsoft Academic Search

    Teresa Znamierowska; Szymon Bandrowski

    2008-01-01

    The NdPO4–Na4P2O7–NaPO3 system being part of the Nd2O3–Na2O–P2O5 oxide system was investigated by thermoanalytical methods, X-ray powder diffraction and microscopy in reflected light. On the basis of the obtained results its phase diagram is proposed. The investigated partial system is bounded by three subsystems (i) NdPO4–NaPO3, (ii) Na4P2O7–NaPO3 and (iii) NdPO4–Na4P2O7. In the system NdPO4–NaPO3 an intermediate compound – NaNdP2O7

  16. Analysis of the d.c. and a.c. properties of K 2 O-doped porous Ba 0.5 Sr 0.5 TiO 3 ceramic humidity sensor

    Microsoft Academic Search

    Y. C. Yeh; T. Y. Tseng

    1989-01-01

    A humidity sensor using K2O-doped porous Ba0.5Sr0.5TiO3 ceramic is investigated. This ceramic humidity sensor exhibits a porous structure. The porous ceramic easily absorbs water\\u000a vapour throughout the pores. The log-conductance against relative humidity (r.h.) sensitivity of this sensor is greater than\\u000a 4 orders of magnitude in the range of 15?95% r.h. at 400 Hz and 25C. The adsorption process of

  17. The effect of P 2O 5 on the crystallization and microstructure of glass-ceramics in the SiO 2–Li 2O–K 2O–ZnO–P 2O 5 system

    Microsoft Academic Search

    Sascha Cramer von Clausbruch; Marcel Schweiger; Wolfram Höland; Volker Rheinberger

    2000-01-01

    Six glasses in the SiO2–Li2O–K2O–ZnO–P2O5 system were prepared, varying the P2O5 content from 0.0 to 2.5 mol% with the molar ratios of the other components being invariant. Crystallization processes of these glasses were investigated using high temperature XRD and differential scanning calorimetry. Morphology and microstructure of the glass-ceramics were studied using scanning electron microscopy. Crystallization of these glasses occurred in

  18. In vitro cellular adhesion and antimicrobial property of SiO 2 –MgO–Al 2 O 3 –K 2 O–B 2 O 3 –F glass ceramic

    Microsoft Academic Search

    Sushma Kalmodia; Atiar Rahaman Molla; Bikramjit Basu

    2010-01-01

    The aim of the present study was to examine the cellular functionality and antimicrobial properties of SiO2–MgO–Al2O3–K2O–B2O3–F glass ceramics (GC) containing fluorophlogopite as major crystalline phase. The cellular morphology and cell adhesion study\\u000a using human osteoblast-like Saos-2 cells and mouse fibroblast L929 cells reveals good in vitro cytocompatibility of GC. The\\u000a potential use of the GC for biomedical application was

  19. Updated: 9/10/2013 1 Xinyu (Jason) CAO

    E-print Network

    Levinson, David M.

    Investigator: David Levinson; Investigator: Jason Cao, Yingling Fan, Greg Lindsey, Michael Iacono), MnDOT, $261-motorized traffic, 2011-2013. (Principal Investigator: Greg Lindsey; Investigator: Jason Cao), MnDOT, $99,948. 6, planning, engineering, health, law, and humanities, 2009-2010, (Principal Investigators: Greg Lindsey

  20. Effect of pH values on surface modification and solubility of phosphate bioglass-ceramics in the CaO-P 2O 5-Na 2O-SrO-ZnO system

    NASA Astrophysics Data System (ADS)

    Li, Xudong; Cai, Shu; Zhang, Wenjuang; Xu, Guohua; Zhou, Wei

    2009-08-01

    The bioactive glass-ceramics in the CaO-P 2O 5-Na 2O-SrO-ZnO system were synthesized by the sol-gel technique, and then chemically treated at different pH values to study the solubility and surface modification. Samples sintered at 650 °C for 4 h consisted of the crystalline phase ?-Ca 2P 2O 7 and the glass matrix. After soaking in the solution at pH 1.0, the residual glass matrix on the surface appeared entirely dissolved and no new phase could be detected. Whereas at pH 3.0, web-like layer exhibiting peaks corresponding to CaP 2O 6 was formed and covered the entire surface of the sample. When conducted at pH 10.0, only part of the glass matrix was dissolved and a new phase Ca 4P 6O 19 was precipitated, forming the petaline layer. The chemical treatment can easily change the surface morphologies and phase composition of this bioactive glass-ceramics. The higher level of surface roughness resulting from the new-formed layer would improve the interface bonding and benefit for cell adhesion.

  1. Enhanced 1.53-?m and lowered upconversion luminescence in Er3+-doped Ga2O3-GeO2-Bi2O3-Na2O glass by codoping rare earths

    NASA Astrophysics Data System (ADS)

    Shi, D. M.; Zhao, Y. G.; Wang, X. F.

    2011-07-01

    Spectroscopic properties and energy transfer (ET) in Ga2O3-GeO2-Bi2O3-Na2O (GGBN, glass doped with Er3+ and rare earths (RE3+; RE3+=Ce3+, Tb3+) have been investigated. Intense 1.53-?m emission with the peak emission cross-section achieved to 7.58×10-21 cm2 from Er3+-doped GGBN glass has been obtained upon excitation at 980 nm. Effects of RE3+ (RE3+=Ce3+, Tb3+) codoping on the optical properties of Er3+-doped GGBN glass have been investigated and the possible ET mechanisms involved have also been discussed. Significant enhancement of the 1.53 ?m emission intensity and decrease of upconversion (UC) fluorescence with increasing Ce3+ concentration have been observed. The incorporation of Tb3+ into Er3+-doped GGBN glass could significantly decrease the UC emission intensity, but meanwhile decrease the 1.53 ?m emission intensity due to the ET from Er3+:4I13/2 to Tb3+:7F2. The results indicate that the incorporation of Ce3+ into Er3+-doped GGBN glass can effectively improve 1.53-?m and lower UC luminescence, which makes GGBN glass more attractive for use in C-band optical fiber amplifiers.

  2. Structure vs. composition: A solid-state 1H and 29Si NMR study of quenched glasses along the Na 2O-SiO 2-H 2O join

    NASA Astrophysics Data System (ADS)

    Cody, George D.; Mysen, Bjorn O.; Lee, Sung Keun

    2005-05-01

    A suite of six hydrous (7 wt.% H 2O) sodium silicate glasses spanning sodium octasilicate to sodium disilicate in composition were analyzed using 29Si single pulse (SP) magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, 1H- 29Si cross polarization (CP) MAS NMR, and fast MAS 1H-NMR. From the 29Si SPMAS data it is observed that at low sodium compositions dissolved water significantly depolymerizes the silicate network. At higher sodium contents, however, dissolved H 2O does not affect a significant increase in depolymerization over that predicted based on the Na/Si ratio alone. The fast MAS 1H-NMR data reveal considerable complexity in proton environments in each of the glasses studied. The fast MAS 1H-NMR spectra of the highest sodium concentration glasses do not exhibit evidence of signficantly greater fractions of dissolved water as molecular H 2O than the lower sodium concentration glasses requiring that the decrease in polymerization at high sodium contents involves a change in sodium solution mechanism. Variable contact time 1H- 29Si cross polarization (CP) MAS NMR data reveal an increase in the rotating frame spin lattice relaxation rate constant ( T1?*) for various Q n species with increasing sodium content that correlates with a reduction in the average 1H- 29Si coupling strength. At the highest sodium concentration, however, T1?* drops significantly, consistent with a change in the Na 2O solution mechanism.

  3. Thermal Stability and Infrared-To Upconversion Emissions of Er3+/Yb3+ Co-Doped 70GeO2-20PbO-10K2O Glasses

    NASA Astrophysics Data System (ADS)

    Ahmed, Samah M.; Shaltout, I.; Badr, Y.

    2011-06-01

    Er3+/Yb3+ co-doped potassium-lead-germanate (70GeO2-20PbO-10K2O) glasses with a fixed concentration of Er3+ ions (0.5 mol. %) and different concentrations of Yb3+ ions (0, 0.5, 1.5, and 2.5 mol. %), have been synthesized by the conventional melting and quenching method. The structure and vibrational modes of the glass network were investigated by the infrared absorption and Raman spectroscopy. The thermal behavior of all glass samples was investigated by the differential thermal analysis. Infrared-to-visible frequency upconversion process was investigated in all glasses. Intense green and red upconversion emission bands centered at around 532, 546, and 655 nm were observed, underallglasses.Intense excitation at 980 nm of diode laser at room temperature. The dependence of these emissions on the excitation power was investigated.

  4. Magnetic and optical investigation of 40SiO2·30Na2O·1Al2O3·(29 - x)B2O3·xFe2O3 glass matrix

    NASA Astrophysics Data System (ADS)

    Dantas, Noelio O.; Ayta, Walter E. F.; Silva, Anielle C. A.; Cano, Nilo F.; Rodriguez, Anselmo F. R.; Oliveira, Aderbal C.; Garg, Vijayendra K.; Morais, Paulo C.

    2012-08-01

    Samples of 40SiO2·30Na2O·1Al2O3·(29 - x)B2O3·xFe2O3 (mol%), with 0.0 ? x ? 17.5, were prepared by the fusion method and investigated by electron paramagnetic resonance (EPR), optical absorption (OA) and Mössbauer spectroscopy (MS). The EPR spectra of the as-synthesized samples exhibit two well-defined EPR signals around g = 4.27 and g = 2.01 and a visible EPR shoulder around g = 6.4, assigned to isolated Fe3+ ion complexes (g = 4.27 and g = 6.4) and Fe3+-based clusters (g = 2.01). Analyses of both EPR line intensity and line width support the model picture of Fe3+-based clusters built in from two sources of isolated ions, namely Fe2+ and Fe3+; the ferrous ion being used to build in iron-based clusters at lower x-content (below about x = 2.5%) whereas the ferric ion is used to build in iron-based clusters at higher x-content (above about x = 2.5%). The presence of Fe2+ ions incorporated within the glass template is supported by OA data with a strong band around 1100 nm due to the spin-allowed 5Eg-5T2g transition in an octahedral coordination with oxygen. Additionally, Mössbauer data (isomer shift and quadrupole splitting) confirm incorporation of both Fe2+ and Fe3+ ions within the template, more likely in tetrahedral-like environments. We hypothesize that ferrous ions are incorporated within the glass template as FeO4 complex resulting from replacing silicon in non-bridging oxygen (SiO3O-) sites whereas ferric ions are incorporated as FeO4 complex resulting from replacing silicon in bridging-like oxygen silicate groups (SiO4).

  5. Physicochemical properties of Cs borosilicate glasses containing CaO

    Microsoft Academic Search

    D. Banerjee; V. Sudarsan; A. Joseph; I. J. Singh; J. Nuwad; C. G. S. Pillai; P. K. Wattal; D. Das

    2011-01-01

    A series of Cs-borosilicate glasses of general formula (mol%): 17.5Na2O–2.5Cs2O–45SiO2–(35-x)B2O3–xCaO, where x varies from 0 to 10, were prepared by conventional melt quenching technique. Physicochemical properties like glass transition temperature, extent of volatilization loss of Cs and chemical durability of these glasses have been investigated in detail. Based on the Tg values obtained from DSC studies, it is confirmed that

  6. CAOS spectroscopy of Am stars Kepler targets

    NASA Astrophysics Data System (ADS)

    Catanzaro, G.; Ripepi, V.; Biazzo, K.; Busá, I.; Frasca, A.; Leone, F.; Giarrusso, M.; Munari, M.; Scuderi, S.

    2015-07-01

    The Kepler space mission and its K2 extension provide photometric time series data with unprecedented accuracy. These data challenge our current understanding of the metallic-lined A stars (Am stars) for what concerns the onset of pulsations in their atmospheres. It turns out that the predictions of current diffusion models do not agree with observations. To understand this discrepancy, it is of crucial importance to obtain ground-based spectroscopic observations of Am stars in the Kepler and K2 fields in order to determine the best estimates of the stellar parameters. In this paper, we present a detailed analysis of high-resolution spectroscopic data for seven stars previously classified as Am stars. We determine the effective temperatures, surface gravities, projected rotational velocities, microturbulent velocities and chemical abundances of these stars using spectral synthesis. These spectra were obtained with CAOS, a new instrument recently installed at the observing station of the Catania Astrophysical Observatory on Mt Etna. Three stars have already been observed during quarters Q0-Q17, namely: HD 180347, HD 181206 and HD 185658, while HD 43509 was already observed during K2 C0 campaign. We confirm that HD 43509 and HD 180347 are Am stars, while HD 52403, HD 50766, HD 58246, HD 181206 and HD 185658 are marginal Am stars. By means of non-LTE (local thermodynamic equilibrium) analysis, we derived oxygen abundances from O I ?7771-5 Å triplet and we also discussed the results obtained with both non-LTE and LTE approaches.

  7. The 1.53 ?m spectroscopic properties and thermal stability in Er3+/Ce3+ codoped TeO2-WO3-Na2O-Nb2O5 glasses

    NASA Astrophysics Data System (ADS)

    Zheng, Shichao; Zhou, Yaxun; Yin, Dandan; Xu, Xingchen; Qi, Yawei; Peng, Shengxi

    2013-05-01

    Er3+/Ce3+ codoped tellurite-based glasses with composition of TeO2-WO3-Na2O-Nb2O5 were prepared by high-temperature melt-quenching technique and a detailed study of the 1.53 ?m band spectroscopic properties and thermal stability was presented in this paper. The absorption spectra, visible upconversion spectra, 1.53 ?m band fluorescence spectra, fluorescence lifetimes, Raman spectra, differential scanning calorimeter (DSC) and X-ray diffraction (XRD) curves of glass samples were measured and investigated, together with the quantitative calculations and analyses of Judd-Ofelt intensity parameters, stimulated emission and absorption cross-sections, amplification quality factors, energy transfer rates and quantum transition efficiencies. It was found that the prepared glass samples have good thermal stability (Tg>425 °C), large Judd-Ofelt intensity parameter (?6>0.80×10-20 cm2) and bandwidth quality factor (?ep×FWHM>360×10-21 cm2 nm) of Er3+. With the increasing of Ce3+ doped concentration, the visible upconversion emission decreased while the 1.53 ?m band fluorescence intensity improved significantly due to the enhanced energy transfer of Er3+:4I11/2+Ce3+:2F5/2?Er3+:4I13/2+Ce3+:2F7/2 owing to the moderate phonon energy (˜930 cm-1) of glass host, which was beneficial in compensating for the existing energy mismatch between the Er3+:4I11/2?4I13/2 emission and Ce3+:2F5/2?2F7/2 absorption transitions. Compared with the Er3+ single-doped case, the 1.53 ?m band fluorescence intensity in Er3+/Ce3+ codoped glass sample could increase by about 30%. The results indicate that the prepared tellurite-based glass with a suitable Er3+/Ce3+ codoping concentration is an excellent gain medium applied for broadband EDFA pumped with a 980 nm laser diode.

  8. Ionic conductivity of mixed glass former 0.35Na(2)O + 0.65[xB(2)O(3) + (1 - x)P(2)O(5)] glasses.

    PubMed

    Christensen, Randilynn; Olson, Garrett; Martin, Steve W

    2013-12-27

    The mixed glass former effect (MGFE) is defined as a nonlinear and nonadditive change in the ionic conductivity with changing glass former fraction at constant modifier composition between two binary glass forming compositions. In this study, mixed glass former (MGF) sodium borophosphate glasses, 0.35Na2O + 0.65[xB2O3 + (1 - x)P2O5], 0 ? x ? 1, have been prepared, and their sodium ionic conductivity has been studied. The ionic conductivity exhibits a strong, positive MGFE that is caused by a corresponding strongly negative nonlinear, nonadditive change in the conductivity activation energy with changing glass former content, x. We describe a successful model of the MGFE in the conductivity activation energy terms of the underlying short-range order (SRO) phosphate and borate glass former structures present in these glasses. To do this, we have developed a modified Anderson-Stuart (A-S) model to explain the decrease in the activation energy in terms of the atomic level composition dependence (x) of the borate and phosphate SRO structural groups, the Na(+) ion concentration, and the Na(+) mobility. In our revision of the A-S model, we carefully improve the treatment of the cation jump distance and incorporate an effective Madelung constant to account for many body coulomb potential effects. Using our model, we are able to accurately reproduce the composition dependence of the activation energy with a single adjustable parameter, the effective Madelung constant, that changes systematically with composition, x, and varies by no more than 10% from values typical of oxide ceramics. Our model suggests that the decreasing columbic binding energies that govern the concentration of the mobile cations are sufficiently strong in these glasses to overcome the increasing volumetric strain energies (mobility) caused by strongly increasing glass-transition temperatures combined with strongly decreasing molar volumes of these glasses. The dependence of the columbic binding energy term on the relative high-frequency dielectric permittivity suggests that the increased polarizability of the bridging oxygens connecting SRO tetrahedral boron units to phosphorus units causes further charge delocalization away from the negatively charged tetrahedral boron units, leading to a lowering of the charge density, and is the underlying cause of the MGFE. PMID:24295052

  9. Understanding Structural Properties of Carbonate-Silicate Melts: An EXAFS Study on Y and Sr in the System Na2O-CaO-Al2O3-SiO2-CO2

    NASA Astrophysics Data System (ADS)

    Pohlenz, J.; Pascarelli, S.; Mathon, O.; Belin, S.; Shiryaev, A.; Safonov, O.; Murzin, V.; Shablinskaya, K.; Irifune, T.; Wilke, M.

    2014-12-01

    Carbonatite volcanism generally occurs in intra-plate settings associated with continental rifting. The only active carbonatitic volcano is the Oldoinyo Lengai, Tanzania, which generates sodium-rich carbonatites in close association with phonolites and nephelinites1. The processes of carbonatite genesis are still unresolved, however carbonate-bearing melts evidently play a crucial role during mantle melting, in diamond formation and as metasomatic agents. Carbonate melts show extraordinary properties, especially in regard to their low melt viscosities and densities, high surface tensions and electrical conductivities as well as distinct geochemical affinities to a wide range of trace elements2. Understanding the structural properties of carbonate-bearing melts is fundamental to explaining their chemical and physical behaviour as well as modeling processes operating in the deep Earth. Extended X-ray absorption fine structure (EXAFS) spectroscopy is a versatile tool for element specific investigation of the short to medium range structure of melts and glasses. This study focuses on unraveling the influence of carbonate concentration on the structural incorporation of the geochemically important trace elements Y and Sr in silicate and carbonate melts in the system Na2O-CaO-Al2O3-SiO2-CO2. First, we present structural data of silicate glasses with up to 10 wt% CO2, quenched from melts under high temperature and pressure, which indicate that the local structure of Y and Sr is not or only slightly affected by CO2. Melts with higher CO2 contents could not be quenched to glass, so far. Second, we show results of high pressure, high temperature experiments conducted in the Paris Edinburgh-Press, which provides in-situ insight into carbonate-silicate melts. All EXAFS measurements were performed at the synchrotron facility beamlines SAMBA (SOLEIL) and BM23 (ESRF). Information derived from the trace elements' local structure is used to develop a structural model for carbonate-silicate melts. The ultimate goal is to gain insight into the structural control on chemical fractionation processes in carbonate-bearing magmatic systems in the deep Earth. 1. Klaudius, J & Keller, J, Lithos 91, 173-190 (2006). 2. Jones, AP, Genge, M & Carmody, L, Rev. Mineral. Geochem. 75, 289-322 (2013).

  10. In-situ measurements of D/H fractionation between melt and coexisting aqueous fluids in the Na2O-Al2O3-SiO2-H2O system

    NASA Astrophysics Data System (ADS)

    Dalou, C.; Le Losq, C.; Mysen, B. O.

    2014-12-01

    Hydrogen isotope partitioning (as H2O and D2O) between water-saturated silicate melts and coexisting silicate-saturated aqueous fluids with several different initial D/H ratios in the Na2O-Al2O3-SiO2-H2O system has been determined. In-situ measurements in a hydrothermal diamond anvil cell (HDAC) with the fluid and melt at the desired temperatures (?800?C) and pressures (?1115 MPa) were carried out with microRaman and FTIR spectroscopy techniques. For bulk D/H ratios were used: 0.05 ±0.02, 0.13 ±0.05, 0.53 ±0.01 and 2.35 ±0.04. Three experimental series (D/H: 0.05, 0.13, 0.53) with coexisting fluid and melt have comparable pressure/temperature trajectories (350-650 ºC/322-626, 313-741 and MPa; 248-648 MPa, respectively), whereas the experimental series with D/H=2.35 had a lower pressure/temperature trajectory (400-680 ºC/192-496 MPa). In these pressure/temperature ranges, the D/H ratios of fluids barely change with temperature, with an average small negative ?Hfluid -1.2 ±0.5 kJ/mol. In contrast, the D/H ratios of coexisting melts display strong temperature dependence. The ?Hmelt decreases from 14.6 ±2.2 to -3.7 ±1.1 kJ/mol with the D/H ratio increasing from 0.05 ±0.02 to 2.35 ±0.04. Consequently, the (D,H) exchange equilibrium between melt and fluid is temperature dependent, and varies so that its ?H increases from -15.9 ±2.7 to 0.3 ±0.4 kJ/mol with increasing D/H ratios. Hydrogen isotope fractionation between silicate melts and low density phases (aqueous fluids or gases) may affect the ?D values during, for example degassing of mantle derived-magmatic liquids. Moreover, D/H fractionation between silicate minerals and melts in the Earth's interior can be affected by the significant temperature and composition-dependent D/H fractionation in silicate melts at high temperatures and pressures.

  11. Optical properties of nanocrystalline potassium lithium niobate in the glass system (100-x) TeO2-x(1.5K2O-Li2O-2.5Nb2O5).

    PubMed

    Ahamad, M Niyaz; Varma, K B R

    2009-08-01

    Optically clear glasses of various compositions in the system (100-x) TeO2-x(1.5K2O-Li2O-2.5Nb2O5) (2 < or = x < or = 12, in molar ratio) were prepared by the melt-quenching technique. The glassy nature of the as-quenched samples was established via differential scanning calorimetry (DSC). The amorphous and the crystalline nature of the as-quenched and heat-treated samples were confirmed by the X-ray powder diffraction and transmission electron microscopic (TEM) studies. Transparent glasses comprising potassium lithium niobate (K3Li2Nb5O15) microcrystallites on the surface and nanocrystallites within the glass were obtained by controlled heat-treatment of the as-quenched glasses just above the glass transition temperature (T(g)). The optical transmission spectra of these glasses and glass-crystal composites of various compositions were recorded in the 200-2500 nm wavelength range. Various optical parameters such as optical band gap, Urbach energy, refractive index were determined. Second order optical non-linearity was established in the heat-treated samples by employing the Maker-Fringe method. PMID:19928168

  12. Effects of nano-YAG (Y 3Al 5O 12) crystallization on the structure and photoluminescence properties of Nd 3+-doped K 2O-SiO 2-Y 2O 3-Al 2O 3 glasses

    NASA Astrophysics Data System (ADS)

    Tarafder, Anal; Molla, Atiar Rahaman; Karmakar, Basudeb

    2010-10-01

    Nd 3+-doped precursor glass in the K 2O-SiO 2-Y 2O 3-Al 2O 3 (KSYA) system was prepared by the melt-quench technique. The transparent Y 3Al 5O 12 (YAG) glass-ceramics were derived from this glass by a controlled crystallization process at 750 °C for 5-100 h. The formation of YAG crystal phase, size and morphology with progress of heat-treatment was examined by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Fourier transformed infrared reflectance spectroscopy (FT-IRRS). The crystallite sizes obtained from XRD are found to increase with heat-treatment time and vary in the range 25-40 nm. The measured photoluminescence spectra have exhibited emission transitions of 4F 3/2 ? 4I J ( J = 9/2, 11/2 and 13/2) from Nd 3+ ions upon excitation at 829 nm. It is observed that the photoluminescence intensity and excited state lifetime of Nd 3+ ions decrease with increase in heat-treatment time. The present study indicates that the incorporation of Nd 3+ ions into YAG crystal lattice enhance the fluorescence performance of the glass-ceramic nanocomposites.

  13. Phosphate base laser glasses

    SciTech Connect

    Izumitani, T.; Tsuru, M.

    1980-12-16

    A phosphate base laser glass comprising 55-70% P2O5, 1-15% Al2O3, 0-25% Li2O, 0-25% Na2O, 0-8% K2O, the total proportion of Li2O, Na2O, and K2O being 10-25%, 0-15% BaO, 0-15% ZnO, 0-15% CaO , 0-15%, sro, 0-15% MgO, the total proportion of BaO, ZnO, CaO, SrO, and MgO being 5-15%, 0-5% Y2O3, 0-5% La2O3, 0-5% GeO2, 0-5% CeO2, 0-3% Nb2O5, 0-3% MnO2, 0-2% Ta2O5, 0-1% Sb2O3, and 0.01-5% Nd2O3, all % being mole %. The phosphate base laser glass of this invention has a high induced emission cross section, a low non-linear refractive index coefficient, and excellent acid resistance and divitrification resistance. By replacing partially or wholely one or more of LiO2, Na2O, K2O, BaO, ZnO, CaO, SrO, MgO or Al2O3 by LiF, NaF, KF , BaF2ZnF2, CaF2, SrF2, MgF2 or AlF3, respectively, the above properties of the laser glass are further improved.

  14. Effect of Bi2O3 addition on electron paramagnetic resonance, optical absorption, and conductivity in vanadyl-doped Li2O-K2O-Bi2O3-B2O3 glasses.

    PubMed

    Subhadra, M; Kistaiah, P

    2011-02-17

    Glasses with composition 15Li(2)O-15K(2)O-xBi(2)O(3)-(65 - x)-B(2)O(3)/5V(2)O(5) (3 ? x ? 15) have been prepared by the conventional melt quench technique. The electron paramagnetic resonance spectra of VO(2+) in these glasses have been recorded in the X-band frequency (?9.3 GHz) at room temperature. The spin Hamiltonian parameters and covalency rates were evaluated. It was found that the V(4+) ions exist as vanadyl (VO(2+)) ions and are in an octahedral coordination with a tetragonal compression. The covalency rates (1 - ?(2)) and (1 - ?(2)) indicate moderate covalency for the ?- and ?-bonds. It was observed that the spin-Hamiltonian parameters depend slightly on the relative concentration of Bi(2)O(3). The optical properties of this glass system are studied from the optical absorption spectra recorded in the wavelength range 200-800 nm. The fundamental absorption edge has been identified from the optical absorption spectra. The values of optical band gap for indirect allowed transitions have been determined using available theories. The direct current electrical conductivity, ?, has been measured in the temperature range 373-573 K. The conductivity decreases with the increase in Bi(2)O(3) concentration. This has been discussed in terms of the decrease in the number of mobile ions and their mobility. An attempt is made to correlate the EPR, optical, and electrical results and to find the effect of Bi(2)O(3) content on these parameters. PMID:21247083

  15. Optical and dielectric properties of isothermally crystallized nano-KNbO3 in Er3+-doped K2O-Nb2O5-SiO2 glasses.

    PubMed

    Chaliha, Reenamoni Saikia; Annapurna, K; Tarafder, Anal; Tiwari, V S; Gupta, P K; Karmakar, Basudeb

    2010-01-01

    Precursor glass of composition 25K(2)O-25Nb(2)O(5)-50SiO(2) (mol%) doped with Er(2)O(3) (0.5 wt% in excess) was isothermally crystallized at 800 degrees C for 0-100 h to obtain transparent KNbO(3) nanostructured glass-ceramics. XRD, FESEM, TEM, FTIRRS, dielectric constant, refractive index, absorption and fluorescence measurements were carried out to analyze the morphology, dielectric, structure and optical properties of the glass-ceramics. The crystallite size of KNbO(3) estimated from XRD and TEM is found to vary in the range 7-23 nm. A steep rise in the dielectric constant of glass-ceramics with heat-treatment time reveals the formation of ferroelectric nanocrystalline KNbO(3) phase. The measured visible photoluminescence spectra have exhibited green emission transitions of (2)H(11/2), (4)S(3/2)-->(4)I(15/2) upon excitation at 377 nm ((4)I(15/2)-->(4)G(11/2)) absorption band of Er(3+) ions. The near infrared (NIR) emission transition (4)I(13/2)-->(4)I(15/2) is detected around 1550 nm on excitation at 980 nm ((4)I(15/2)-->(4)I(11/2)) of absorption bands of Er(3+) ions. It is observed that photoluminescent intensity at 526 nm ((2)H(11/2)-->(4)I(15/2)), 550 nm ((4)S(3/2)-->(4)I(15/2)) and 1550 nm ((4)I(13/2)-->(4)I(15/2)) initially decrease and then gradually increase with increase in heat-treatment time. The measured lifetime (tau(f)) of the (4)I(13/2)-->(4)I(15/2) transition also possesses a similar trend. The measured absorption and fluorescence spectra reveal that the Er(3+) ions gradually enter into the KNbO(3) nanocrystals. PMID:19910241

  16. Behavior of rare earth elements in a paleoweathering profile on granodiorite in the Front Range, Colorado, USA

    Microsoft Academic Search

    Kent C. Condie; Jessie Dengate; Robert L. Cullers

    1995-01-01

    A Paleoweathering profile on the Boulder granodiorite in northern Colorado provides an opportunity to trace the behavior of REEs from parent rock, through a weathering profile, into unconformably overlying Permian sediments. With progressive upward weathering of the granodiorite, Na2O, CaO, SiO2, TaHf, CoTh, CrSc, CrTh, ZrHf, LaSc, ZrY, and LaTh decrease; Al2O3 and Fe2O3T increase; and TiO2, MgO, K2O, P2O5,

  17. Development of glass-ceramics by sintering and crystallization of fine powders of calcium-magnesium-aluminosilicate glass

    Microsoft Academic Search

    D. U. Tulyaganov; M. J. Ribeiro; J. A. Labrincha

    2002-01-01

    Natural raw materials normally used in the ceramic and glass industry were studied for the production of calcium–magnesium–aluminosilicate glass or glass-ceramic materials. Sintering and crystallization processes of fine powders of parent glass with chemical composition (wt.%) 46.00 SiO2, 15.90 Al2O3, 1.20 Fe2O3, 0.42 TiO2, 23.50 CaO, 9.37 MgO, 0.04 Na2O, 0.98 K2O, 1.95 P2O5 and 0.35 CaF2 were studied. Crystallization

  18. Geochemistry of Oceanic Igneous Rocks—Ridges, Islands, and Arcs—with Emphasis on Manganese, Scandium, and Vanadium

    Microsoft Academic Search

    Bruce R. Doe

    1997-01-01

    A database on a number of elements in oceanic volcanic rocks is presented, including the principal major-element oxides-SiO2, TiO2, Al2O3, Fe2O3(T), MnO, MgO, CaO, Na2O, K2O, and P2O5 (where T refers to total iron)–and the trace elements–Ba, Ce, Cr, Cu, Ni, Sc, Sr, V, Pb (mainly by isotope dilution), Yb, Zn, and Zr. Interpretations are given for transition metals, with

  19. Heat capacities and entropies of silicate liquids and glasses

    Microsoft Academic Search

    J. F. Stebbins; I. S. E. Carmichael; L. K. Moret

    1984-01-01

    The heat capacities of several dozen silicate glasses and liquids composed of SiO2, TiO2, Al2O3, Fe2O3, FeO, MgO, CaO, BaO, Li2O, Na2O, K2O, and Rb2O have been measured by differential scanning and drop calorimetry. These results have been combined with data from the literature to fit Cpas a function of composition. A model assuming ideal mixing (linear combination) of partial

  20. Evaluation of distribution, mobility and binding behaviour of heavy metals in surficial sediments of Louro River (Galicia, Spain) using chemometric analysis: a case study

    Microsoft Academic Search

    A. V. Filgueiras; I. Lavilla; C. Bendicho

    2004-01-01

    Contents of total and extractable heavy metals, carbonates, MnO and Fe2O3, organic matter, and matrix components such as SiO2, Al2O3, CaO, Na2O, MgO, TiO2, K2O and P2O5 are used along with principal component analysis (PCA) for studying distribution, mobility and binding behaviour of Cd, Cr, Cu, Ni and Pb in the Louro River (Galicia, Spain). Eleven surficial sediment samples were

  1. Electrical properties of carbon fiber\\/shirasu glass composite

    Microsoft Academic Search

    Yoshihiro Hirata; Yasuo Fukushige; Hiroshi Kuwazuru; Ryoko Yamashita; Soichiro Sameshima; Yoshitake Kamino

    1997-01-01

    A kind of aluminosilicate glass, shirasu glass, with a chemical composition (mass%) of 75.4 SiO2, 14.6 Al2O3, 0.2 TiO2, 1.7 Fe2O3, 0.2 MgO, 1.5 CaO, 3.0 Na2O and 3.6 K2O was pressureless-sintered to full density in air at 1000 °C. The dense glass showed specific resistivity of 1440 ?m at 350 °C and activation energy of 71.7 kJ\\/ mol at

  2. Influence of alkali and alkali-earth metal oxide substitutions on the properties of lithium–iron–phosphate glasses

    Microsoft Academic Search

    Ruijuan Yang; Yinghui Wang; Xiaopeng Hao; Jie Zhan; Shiquan Liu

    2011-01-01

    The influences of different alkali and alkali-earth oxide substitutions on the properties of lithium–iron–phosphate (LIP) glasses have been studied. Na2O, K2O, MgO, CaO and BaO were used to substitute Li2O to prepare LIP glasses with molar compositions of (20?x)Li2O?xR2O(RO)?30Fe2O3?50P2O5 (x=2.4, 4, 5.6 and 7.2). The glass transition temperature (Tg) was determined by the differential thermal analysis technique. The density and

  3. Geochemistry of Henbury impact glass

    Microsoft Academic Search

    S. R. Taylor; P. Kolbe

    1965-01-01

    Glass due to meteorite impact, found north of the main crater at Henbury, Northern Territory, Australia (24° 35' S; 133° 09' E) has the following composition: SiO2 69.5%; Al2O3 11.37%; FeO 11.45%; MgO 2.18%; CaO 0.61%; Na2O 0.83%; K2O 2.98%; TiO2 0.82%. P 150 ppm; Cr 80 ppm; Li 35 ppm; Ni 3300 ppm; Co 300 ppm; Cu 42 ppm;

  4. Apodized multilevel diffractive lenses Q. Cao and J. Jahns

    E-print Network

    Jahns, Jürgen

    Apodized multilevel diffractive lenses Q. Cao and J. Jahns Focusing and imaging are everlasting topics in optical science and optical engineering. In the visible spectral region, the focusing can be realized by refractive lenses and/or multi- level diffractive lenses. And in the spectral regions of soft x

  5. Multi-Strategy Integration for Actionable Trading Agents Longbing Cao

    E-print Network

    Cao, Longbing

    Multi-Strategy Integration for Actionable Trading Agents Longbing Cao Faculty of Information Technology, University of Technology, Sydney, Australia lbcao@it.uts.edu.au Abstract Trading agents are very useful for developing and back-testing quality trading strategies to support smart trading actions

  6. Grid Load Balancing Using Intelligent Agents Junwei Cao1

    E-print Network

    Jarvis, Stephen

    - 1 - Grid Load Balancing Using Intelligent Agents Junwei Cao1 , Daniel P. Spooner* , Stephen A grid load balancing. Each agent is a representative of a local grid resource and utilises predictive application performance data and iterative heuristic algorithms to engineer local load balancing across

  7. Video Synchronization and Its Application on Object Xiaochun Cao a

    E-print Network

    Foroosh, Hassan

    of the linear-combination. Caspi and Irani [6] proposed a direct approach to align two surveillance videosVideo Synchronization and Its Application on Object Transfer Xiaochun Cao a , Lin Wu b , Jiangjian Xiao c , Hassan Foroosh d aObjectVideo Inc., Reston, VA 20191, USA bSchool of Computer Science

  8. Un caos perfecto: El cine de Emir Kusturica

    Microsoft Academic Search

    Evelyn ERLIJ

    Desentrañar la vida de este cineasta, capaz de conv ertir el caos en perfección, es una tortura exquisita sólo para quien tenga en el c uerpo una sobredosis de él suficiente como para soportarla. Aunque su nombre ya está inserto en la historia del séptimo arte como el director que más premios ha ganado en el Festival de Cannes, el

  9. Phase relations in the greenschist-blueschist-amphibolite-eclogite facies in the system Na 2 O-CaO-FeO-MgO-Al 2 O 3 SiO 2 -H 2 O (NCFMASH), with application to metamorphic rocks from Samos, Greece

    Microsoft Academic Search

    Thomas Will; Martin Okrusch; Esther Schmädicke; Guoli Chen

    1998-01-01

    Calculated phase equilibria among the minerals sodic amphibole, calcic amphibole, garnet, chloritoid, talc, chlorite, paragonite,\\u000a margarite, omphacite, plagioclase, carpholite, zoisite\\/clinozoisite, lawsonite, pyrophyllite, kyanite, sillimanite, quartz\\u000a and H2O are presented for the model system Na2O-CaO-FeO-MgO-Al2O3-SiO2-H2O (NCFMASH), which is relevant for many greenschist, blueschist, amphibolite and eclogite facies rocks. Using the activity-composition\\u000a relationships for multicomponent amphiboles constrained by Will and Powell (1992),

  10. Bounded Conjunctive Queries Yang Cao1,2

    E-print Network

    Fan, Wenfei

    Bounded Conjunctive Queries Yang Cao1,2 Wenfei Fan1,2 Tianyu Wo2 Wenyuan Yu3 1 University@act.buaa.edu.cn wyu@fb.com ABSTRACT A query Q is said to be effectively bounded if for all datasets D, there exists a subset DQ of D such that Q(D) = Q(DQ), and the size of DQ and time for fetching DQ are indepen- dent

  11. Steam catalysis in CaO carbonation under low steam partial pressure

    SciTech Connect

    Yang, S.J.; Xiao, Y.H. [Chinese Academy of Science, Beijing (China)

    2008-06-15

    CaO was widely used to capture CO{sub 2} in direct hydrogen production process, where steam always existed simultaneously. The effect of steam on CaO carbonation performance under low steam partial pressure was investigated using a pressurized thermogravimetric apparatus. The experimental results revealed that steam improved CaO carbonation performance significantly no matter whether Ca(OH){sub 2} was produced or not. At 823 K and 0.5 MPa of steam partial pressure, effect of steam on CaO carbonation performance could not be attributed mainly to production of Ca(OH){sub 2} because the hydration rate of CaO was very slow. The main reason was steam catalysis in CaO carbonation. Enhancement of steam on CaO carbonation performance without Ca(OH){sub 2} production could not be attributed to improvement of steam on the physical property, but to catalytic effect of steam. Effects of CaO precursors, CO{sub 2} partial pressure, steam partial pressure, and temperature with steam addition on CaO carbonation performance were also investigated.

  12. Vladykinite, Na3Sr4(Fe2+ )Si8O24: A new complex sheet silicate from peralkaline rocks of

    E-print Network

    Chakhmouradian, Anton

    syenite in the north-central part of the Murun complex in eastern Siberia, Russia (Lat. 58° 22 48 N; LongRoduCtion Potassic peralkaline syenites [wt% K2O > wt% Na2O; mol% Na2O+K2O > mol% Al2O3] are an uncommon type

  13. [Determination of major elements in superphosphate by X-ray fluorescence spectrometry].

    PubMed

    Rui, Yu-Kui; Li, He; Shen, Jian-Bo; Zhang, Fu-Suo

    2008-11-01

    Phosphate fertilizer is one of the most important fertilizers. The authors determined nine kinds of major elements in superphosphate, the most important phosphate fertilizer, by X-ray fluorescence spectrometry. The detection range of SiO2, Al2O3, TFe2O3, MnO, MgO, CaO, Na2O, K2O and P2O5 is 15.0%-90.0%, 0.20%-25.0%, 0.20%-25.0%, 0.01%-0.35%, 0.20%-40.0%, 0.10%-35.0%, 0.10%-7.50%, 0.05%-7.50% and 1.00%-100.00% respectively, and the precision of the method for SiO2, Al2O3, TFe2O3, MnO, MgO, CaO, Na2O, K2O and P2O5 range from 0.20% to 0.005%, so the method of X-ray fluorescence spectrometry is a fast and effectual method for detecting the composition of phosphate fertilizer. The contents of the above elements showed (1) the detected superphosphate content is 18.101% of P2O5, which is accordant to the labeled level (> or = 16%); (2) the detected superphosphate contains much SiO2, TFe2O3, MgO, CaO and K2O, which are necessary for plant growth and the content of which is 16.954%, 1.495%, 1.580%, 21.428% and 1.585% respectively. These data showed that phosphate fertilizer sometimes can supply some trace elements for plants, but we should eliminate the interference effect of these elements when we research the role of phosphorus; (3) superphosphate contains 3.225% of Al2O3, so the authors should attention to the aluminium poison when superphosphate is used chronically. PMID:19271522

  14. CaO as drop-in colloidal catalysts for the synthesis of higher polyglycerols.

    PubMed

    Kirby, Fiona; Nieuwelink, Anne-Eva; Kuipers, Bonny W M; Kaiser, Anton; Bruijnincx, Pieter C A; Weckhuysen, Bert M

    2015-03-23

    Glycerol is an attractive renewable building block for the synthesis of polyglycerols, which find application in the cosmetic and pharmaceutical industries. The selective etherification of glycerol to higher oligomers was studied in the presence of CaO colloids and the data are compared with those obtained from NaOH and CaO. The materials were prepared by dispersing CaO, CaCO3 , or Ca(OH)2 onto a carbon nanofiber (CNF) support. Colloidal nanoparticles were subsequently dispensed from the CNF into the reaction mixture to give CaO colloids that have a higher activity than equimolar amounts of bulk CaO and NaOH. Optimization of the reaction conditions allowed us to obtain a product with Gardner color number <2, containing no acrolein and minimal cyclic byproducts. The differences in the CaO colloids originating from CNF and bulk CaO were probed using light scattering and conductivity measurements. The results confirmed that the higher activity of the colloids originating from CaO/CNF was due to their more rapid formation and smaller size compared with colloids from bulk CaO. We thus have developed a practical method for the synthesis of polyglycerols containing low amounts of Ca. PMID:25684403

  15. CaO as Drop-In Colloidal Catalysts for the Synthesis of Higher Polyglycerols

    PubMed Central

    Kirby, Fiona; Nieuwelink, Anne-Eva; Kuipers, Bonny W M; Kaiser, Anton; Bruijnincx, Pieter C A; Weckhuysen, Bert M

    2015-01-01

    Glycerol is an attractive renewable building block for the synthesis of polyglycerols, which find application in the cosmetic and pharmaceutical industries. The selective etherification of glycerol to higher oligomers was studied in the presence of CaO colloids and the data are compared with those obtained from NaOH and CaO. The materials were prepared by dispersing CaO, CaCO3, or Ca(OH)2 onto a carbon nanofiber (CNF) support. Colloidal nanoparticles were subsequently dispensed from the CNF into the reaction mixture to give CaO colloids that have a higher activity than equimolar amounts of bulk CaO and NaOH. Optimization of the reaction conditions allowed us to obtain a product with Gardner color number <2, containing no acrolein and minimal cyclic byproducts. The differences in the CaO colloids originating from CNF and bulk CaO were probed using light scattering and conductivity measurements. The results confirmed that the higher activity of the colloids originating from CaO/CNF was due to their more rapid formation and smaller size compared with colloids from bulk CaO. We thus have developed a practical method for the synthesis of polyglycerols containing low amounts of Ca. PMID:25684403

  16. Thermal reactions of aromatics with CaO. Technical progress report, April 1-August 31, 1983

    SciTech Connect

    Longwell, J.P.; Lai, C.K.; Williams, G.C.; Peters, W.A.

    1983-11-01

    The pyrolysis of m-cresol and 1-methylanthracene was studied over both CaO and quartz over the temperature range of 350 to 800/sup 0/C. Vapor-phase concentration of the model compound was 5 mole percent for m-cresol and 1.8 mole percent for 1-methylanthracene. The calcium oxide significantly increased the rates and extents of pyrolysis of the aromatics, reducing the temperature for a given amount of conversion by at least 120/sup 0/C. A proposed mechanism for pyrolysis of m-cresol over CaO involves formation of calcium-cresol salts, which then undergo further cracking at temperatures above 500/sup 0/C to yield coke, CO, CH/sub 4/, toluene and C/sub 3/H/sub 6/. Chemical condensation reactions were the predominant reactions observed in the pyrolysis of 1-methylanthracene over CaO. A comparison of the pyrolysis results of 1-methylanthracene with those of 9-methylanthracene (studied earlier) indicated that the 1-methyl isomer was slightly less reactive over both solids, and that some of the thermal reactions over CaO were also structure specific. Deactivation of CaO was studied by measuring loss of cumulative cracking activity during pyrolysis of 1-methylanthracene. The decay of CaO activity with overall utilization time (or cumulative amount of feed reacted), was well-fitted by a power-law model. Coke burnoff in O/sub 2/ at temperatures between 600-700/sup 0/C regenerated approx.80 percent of the CaO initial activity. The 20 percent loss is attributed to either formation of CaCO/sub 3/ from the CaO or sintering of the CaO particles during regeneration. 7 refs., 11 figs., 1 tab.

  17. The mineralogy and geochemistry of quartz-tourmaline schlieren in the granites of the Primorsky Complex, Western Baikal Region

    NASA Astrophysics Data System (ADS)

    Savel'eva, V. B.; Bazarova, E. P.; Kanakin, S. V.

    2014-12-01

    Quartz-tourmaline schlieren have been found within rapakivi-like granites of the Early Proterozoic Primorsky Complex in the Western Baikal Region. These rocks are biotite leucogranites with normal alkalinity (A/CNK = 1.00-1.04); a high iron mole fraction (92-95%); a K2O/Na2O value of about 2.0; relatively high F, Li, Rb, Cs, Sn, Pb, Th, and U contents; and low Ba, Sr, Eu, Zn, Sc, and V contents. The schlieren composed of quartz and tourmaline with relics of feldspar also contain fluorite, rare muscovite, chlorite, and accessory rutile, ilmenite, zircon, monazite, xenotime, and bastnäsite. B2O3 and F contents in the schlieren are 2.29-2.63 and 0.30-0.47 wt %, respectively. Fe2O3 (4.8-5.4 wt %), F, and H2O contents are higher in these schlieren than in the host granite, while SiO2, CaO, Na2O, K2O, and P2O5 contents are lower than in host rocks. K2O/Na2O values decrease in the schlieren down to 0.4. Enrichment of the schlieren in Fe and other ore elements (Zn, Co, Cu, Sn, etc.), together with B, F, H2O, and Na, suggests that they crystallized from fluid-saturated melt segregated from aluminosilicate melt in the apical part of a shallow-seated intrusion. The formation of tourmaline may be related to the interaction of the fluid with feldspars in the crystallizing granites; it was accompanied by a separation of fluid F-CO2. Quartz precipitated at the next stage, due to the acidic character of the aqueous fluid. In general, the relationships of minerals in the schlieren indicate distinct fractionation of LREE, HREE, and Y in the fluid-saturated melt.

  18. Variations in Compressive Strength of Geopolymer due to the CaO Added Fly Ash

    NASA Astrophysics Data System (ADS)

    Zhao, Yuqing; Koumoto, Tatsuya; Kondo, Fumiyoshi

    Recently, geopolymer has been a noteworthy material which can be used as a replacement for portland cement. The mechanical characteristics and consistency of the geopolymer are strongly affected by its chemical components of fly ash. The variations in compressive strength of geopolymer due to the CaO added fly ash were investigated in this paper. The compressive strengths of geopolymer were increased with an increase in the curing period, and the characteristics changed from the one of plastic soil material to brittle material such as concrete, regardless of CaO content. Also, the results of compressive strength and modulus of deformation showed their maximum value in the case of 8-10% CaO content. From this result, the maximum characteristics of the strengths were assumed to be exerted in case which the water draining process of geopolymer was balanced with the water absorbing process of additional CaO.

  19. Ubiquitous Intelligence in Agent Mining Longbing Cao, Dan Luo, and Chengqi Zhang

    E-print Network

    Cao, Longbing

    in- telligence, network and web intelligence, organizational intelligence, and social intelligence intelligence, ­ Human intelligence, ­ Domain intelligence, ­ Network intelligence, ­ OrganizationalUbiquitous Intelligence in Agent Mining Longbing Cao, Dan Luo, and Chengqi Zhang Faculty

  20. Physical Interference Driven Dynamic Spectrum Lei Yang, Lili Cao and Heather Zheng

    E-print Network

    Almeroth, Kevin C.

    Physical Interference Driven Dynamic Spectrum Management Lei Yang, Lili Cao and Heather Zheng and difficult process. Current proposals make the problem tractable by simplifying interference con- straints as conflict graphs, but they face potential performance degradation from inaccurate interference estimation

  1. Sensitivity Analysis of Discrete Stochastic Systems Rudiyanto Gunawan,* Yang Cao,y

    E-print Network

    Cao, Yang

    Sensitivity Analysis of Discrete Stochastic Systems Rudiyanto Gunawan,* Yang Cao,y Linda Petzold, University of California, Santa Barbara, California ABSTRACT Sensitivity analysis quantifies the dependence of system behavior on the parameters that affect the process dynamics. Classical sensitivity analysis

  2. Removal of Fluoride from Aqueous Solution by CaO Nanoparticles

    Microsoft Academic Search

    Gaurang Patel; Usha Pal; Shobhana Menon

    2009-01-01

    Colloidal particles of CaO were synthesized by the sol-gel method. The particle morphology was characterized by FT-IR, TGA, DTA, and TEM analysis. The ability of the CaO nanoparticles for removal of fluoride from aqueous solution through adsorption has been investigated. All the experiments were carried out by batch mode. The effect of various parameters viz. contact time, pH effect (pH

  3. Thermal reactions of aromatics with CaO. Final report. [1-Methylanthracene, 9-methylanthracene

    SciTech Connect

    Longwell, J.P.; Ellig, D.L.; Lai, C.K.; Mead, D.W.; Williams, G.C.; Peters, W.A.

    1985-05-01

    The pyrolysis of benzene, toluene, 1-methylnaphthalene, 1-methylanthracene, 9-methylanthracene, m-cresol, and n-heptane was studied over CaO and quartz in a fixed-bed reactor under atmosphere pressure. The reaction temperature spanned the range of 350 to 900/sup 0/C with vapor phase residence time kept between 1 and 2 seconds. Compared to quartz, CaO significantly increased the rates and extents of pyrolysis of the aromatic hydrocarbons, reducing the temperature for a given amount of conversion by at least 100/sup 0/C. The magnitude of this enhancement effect increased with increasing aromaticity, or molecular size, of the compounds. For the light aliphatic, n-heptane, the effect of CaO is minor, with pyrolysis results similar to those observed over quartz and in vapor phase cracking. Coke was the major product for pyrolysis of aromatic compounds over either solid. Detailed examination of the distribution of the volatile products suggests that: (1) condensation reactions were the major pyrolysis reactions over CaO, and (2) some of the active sites on the CaO surface may be related to anion defects in the CaO lattice. CaO deactivation studies show that coke deposits from pyrolysis quickly destroy the CaO activity. Oxygen burnoff of the coke at temperatures between 650 and 800/sup 0/C regenerated 70 to 80% of the initial CaO activity. Pyrolysis of m-cresol on CaO surfaces exhibited acid-base behavior over the temperature range 0 to 550/sup 0/C. The initial pyrolysis rate was rapid but formation of calcium salts of cresol, which have much larger molar volumes than the substrate limited the accessibility of reactant gas to the inner unreacted surface, thus drastically reducing the overall rate of conversion with increasing stone utilization. At temperatures above 550/sup 0/C, these calcium salts decomposed to yield coke, CO, H/sub 2/O and other light hydrocarbon gases. 20 refs., 26 figs., 4 tabs.

  4. Chemical durability and Structural approach of the glass series (40-y) Na2O-yFe2O3-5Al2O3-55P2O5-by IR, X-ray diffraction and Mössbauer Spectroscopy

    NASA Astrophysics Data System (ADS)

    Aqdim, S.; Sayouty, El H.; Elouad, B.; Greneche, J. M.

    2012-02-01

    The relationship between the composition and structure for the glasses of general composition (40-y)Na2O-yFe2O3-5Al2O3-55P2O5 (5<=y<=20), has been studied. The chemical durability and density of these glasses increase with increasing Fe2O3 content. The dissolution rate (DR), calculated from the weight loss in distilled water at 90°C for up to 20 days was ? 3.10-9 g/cm2/mn which is 30 times lower than that of window glass. The structure and valence states of the iron ions in the glasses were investigated using, X-ray diffraction, 57Fe Mössbauer spectrometry, potentiometric analysis, and infrared spectroscopy. Both Mössbauer spectrometry and potentiometric analysis allow to estimate both Fe2+ and Fe3+ contents in all these glasses. X-ray diffraction indicates that the local structure of iron phosphate glasses is related to the short range structures of NaFeP2O7. Infrared spectra indicate the formation of P-O-Fe bonds in the pyrophosphate glasses that replace P-O-Na bonds. The presence of a small content of Al2O3 in the glass seems to play a role as a network modifier. The addition of Fe2O3 to Al2O3 in phosphate glasses favours the enhancement of the formation of pyrophosphate units because iron ions have stronger effect on the depolymerization of metaphosphate chains than the aluminium ions. Finally, the I.R spectra indicate that the presence of P-O-Fe bands of these glasses containing more than 15 mol%Fe2O3 is consistent with their good chemical durability.

  5. Zircon saturation in felsic liquids: Experimental results and applications to trace element geochemistry

    Microsoft Academic Search

    E. Bruce Watson

    1979-01-01

    Hydrothermal experiments were carried out at 2 kbar water pressure, 700 °–800 ° C, with the objective of determining the level of dissolved Zr required for precipitation of zircon from melts in the system SiO2-Al2O3-Na2O-K2O. The saturation level depends strongly upon molar (Na2O + K2O)\\/Al2O3 of the melts, with remarkably little sensitivity to temperature, SiO2 concentration, or melt Na2O\\/ K2O.

  6. Combined effects of Fenton peroxidation and CaO conditioning on sewage sludge thermal drying.

    PubMed

    Liu, Huan; Liu, Peng; Hu, Hongyun; Zhang, Qiang; Wu, Zhenyu; Yang, Jiakuan; Yao, Hong

    2014-12-01

    Joint application of Fenton's reagent and CaO can dramatically enhance sludge dewaterability, thus are also likely to affect subsequent thermal drying process. This study investigated the synergistic effects of the two conditioners on the thermal drying behavior of sewage sludge and the emission characteristics of main sulfur-/nitrogen-containing gases. According to the results, Fenton peroxidation combined with CaO conditioning efficiently promoted sludge heat transfer, reduced the amounts of both free and bound water, and created porous structure in solids to provide evaporation channels, thus producing significant positive effects on sludge drying performance. In this case, the required time for drying was shortened to one-third. Additionally, joint usage of Fenton's reagent and CaO did not increase the losses of organic matter during sludge drying process. Meanwhile, they facilitated the formation of sulfate and sulfonic acid/sulfone, leading to sulfur retention in dried sludge. Both of Fenton peroxidation and CaO conditioning promoted the oxidation, decomposition, and/or dissolution of protein and inorganic nitrogen in sludge pre-treatment. As a consequence, the emissions of sulfurous and nitrogenous gases from dewatered sludge drying were greatly suppressed. These indicate that combining Fenton peroxidation with CaO conditioning is a promising strategy to improve drying efficiency of sewage sludge and to control sulfur and nitrogen contaminants during sludge thermal drying process. PMID:25289973

  7. Thermodynamics of strained vanadium dioxide single crystals Yijia Gu, Jinbo Cao, Junqiao Wu, and Long-Qing Chen

    E-print Network

    Chen, Long-Qing

    Thermodynamics of strained vanadium dioxide single crystals Yijia Gu, Jinbo Cao, Junqiao Wu by grain growth and interface barrier Appl. Phys. Lett. 99, 212105 (2011) Strain control of orbital;Thermodynamics of strained vanadium dioxide single crystals Yijia Gu,1,a Jinbo Cao,2 Junqiao Wu,2 and Long

  8. Chlorophyll antenna size adjustments by irradiance in Dunaliella salina involve coordinate regulation of chlorophyll a oxygenase (CAO)

    E-print Network

    ) regulation of both CAO and Lhcb gene expression by irradiance. Inhibitor studies and transient activation regulation of chlorophyll a oxygenase (CAO) and Lhcb gene expression Tatsuru Masuda, Ayumi Tanaka, Anastasios addressed the regulation of expression of genes encoding a variety of chlorophyll biosynthesis enzymes

  9. Petrology and geochemistry of potassic and ultrapotassic volcanism in central Italy: petrogenesis and inferences on the evolution of the mantle sources

    NASA Astrophysics Data System (ADS)

    Conticelli, Sandro; Peccerillo, Angelo

    1992-11-01

    Major, trace element, Sr isotopic and mineral chemical data are reported for mafic volcanic rocks (Mg-value ? 65) from the northern-central sector of the potassic volcanic belt of Central Italy. The rocks investigated range from potassic series (KS) and high-K series (HKS) to lamproitic (LMP) and kamafugitic (KAM) through a transitional series (TRANS), thus covering the entire compositional spectrum of potassic and ultrapotassic magmas. KAM rocks are strongly silica undersaturated and, compared with the other rock series, have low SiO 2, Al 2O 3, Na 2O, Sc and V and high CaO, K/Na, (Na + K)/Al. KS and HKS have high Al 2O 3, CaO and variable enrichment in K 2O and incompatible elements. LMP rocks are saturated in silica and have high SiO 2, K 2O, K 2O/Na 2, MgO, Ni and Cr and low Al 2O 3, CaO, Na 2O, Sc and V. TRANS rocks display intermediate compositional characteristics between LMP and KS. All the rocks under study have fractionated hygromagmaphile element patterns with high LIL/HFS element values and negative anomalies of Ti, Ta, Nb and Ba. Negative Sr anomalies are observed in the LMP and TRANS rocks. LIL elements show overall positive correlations with K 2O, whereas different trends of Sr and HFSE vs. K 2O are defined by LMP-TRANS and KS-HKS-KAM. 87Sr/ 86Sr range from about 0.710 to 0.716. KS, HKS and KAM rocks have similar 87Sr/ 86Sr values clustering around 0.710. LMP and TRANS rocks have the highest 87Sr/ 86Sr values. Geochemical and isotopic data reported for the most primitive Italian potassic and ultrapotassic rocks support the hypothesis that the interaction between crustal and mantle reservoirs was a main process in the genesis of Italian potassic magmatism. Simple mass balance calculations exclude, however, an important role of crustal assimilation during ascent of subcrustal magmas to the surface and indicate that the sources of Central Italy volcanics underwent contamination with fluids and/or melts released by upper crustal material previously brought into the mantle by subduction processes. Different trends of incompatible elements vs. K 2O observed in the studied rocks suggest distinct metasomatic processes for the sources of the investigated magmas. Liquids derived by bulk melting of pelitic sediments are believed to be the most likely contaminants of the source of LMP rocks. Fluids or melts rich in Ca, Sr and with high LILE/HFSE value and Sr isotopic composition around 0.710 are the most likely contaminant of the source region of KS, HKS and KAM volcanics. Variations in CaO, Na 2O and ferromagnesian element abundances and ratios suggest that, in some zones, the mantle source of potassic magmas experienced partial melting with extraction of basaltic liquids prior to metasomatism.

  10. Experimental derivation of nepheline syenite and phonolite liquids by partial melting of upper mantle peridotites

    NASA Astrophysics Data System (ADS)

    Laporte, Didier; Lambart, Sarah; Schiano, Pierre; Ottolini, Luisa

    2014-10-01

    Piston-cylinder experiments were performed to characterize the composition of liquids formed at very low degrees of melting of two fertile lherzolite compositions with 430 ppm and 910 ppm K2O at 1 and 1.3 GPa. We used the microdike technique (Laporte et al., 2004) to extract the liquid phase from the partially molten peridotite, allowing us to analyze liquid compositions at degrees of melting F down to 0.9%. At 1.3 GPa, the liquid is in equilibrium with olivine + orthopyroxene + clinopyroxene + spinel in all the experiments; at 1 GPa, plagioclase is present in addition to these four mineral phases up to about 5% of melting (T?1240 °C). Important variations of liquid compositions are observed with decreasing temperature, including strong increases in SiO2, Na2O, K2O, and Al2O3 concentrations, and decreases in MgO, FeO, and CaO concentrations. The most extreme liquid compositions are phonolites with 57% SiO2, 20-22% Al2O3, Na2O + K2O up to 14%, and concentrations of MgO, FeO, and CaO as low as 2-3%. Reversal experiments confirm that low-degree melts of a fertile lherzolite have phonolitic compositions, and pMELTS calculations show that the amount of phonolite liquid generated at 1.2 GPa increases from 0.3% in a source with 100 ppm K2O to 3% in a source with 2000 ppm K2O. The enrichment in silica and alkalis with decreasing melt fraction is coupled with an increase of the degree of melt polymerization, which has important consequences for the partitioning of minor and trace elements. Thus Ti4+ in our experiments and, by analogy with Ti4+, other highly charged cations, and rare earth elements become less incompatible near the peridotite solidus. Our study brings a strong support to the hypothesis that phonolitic lavas or their plutonic equivalents (nepheline syenites) may be produced directly by partial melting of upper mantle rock-types at moderate pressures (1-1.5 GPa), especially where large domains of the subcontinental lithospheric mantle has been enriched in potassium by metasomatism. The circulation of low-degree partial melts of peridotites into the upper mantle may be responsible for a special kind of metasomatism characterized by Si- and alkali-enrichment. When they are unable to escape by porous flow, low-degree melts will ultimately be trapped inside neighboring olivine grains and give rise to the silica- and alkali-rich glass inclusions found in peridotite xenoliths.

  11. Postcombustion Capture of CO2 with CaO in a Circulating Fluidized Bed Carbonator

    NASA Astrophysics Data System (ADS)

    Alonso, M.; Rodriguez, N.; González, B.; Grasa, G.; Murillo, R.; Abanades, J. C.

    There is an emerging postcombustion capture technology that uses CaO to capture CO2 from combustion flue gases in a circulating fluidized bed reactor. This paper summarizes recent work conducted at CSIC to understand and develop this technology. The paper includes experimental results at conditions close to those expected in the real system, carried out in continuous mode in a 30kW test facility made up of two interconnected circulating fluidized bed reactors. In one of the reactors, CO2 is captured from the gas phase by the CaO continuously circulating from a calciner. In the second reactor, the CaCO3 formed in the carbonator is regenerated to CaO and CO2 by calcination. Modeling of the system at process level, at reactor level (in particular the CFB carbonator), and at particle level (decay in capture capability of CaO) is also outlined. The work carried out so far confirms that the carbonator reactors can be designed to attain capture efficiencies between 70-90%, operating at fluid dynamic conditions close to those present in circulating fluidized bed combustors.

  12. Sensor Relocation in Mobile Sensor Networks Guiling Wang, Guohong Cao, Tom La Porta, and Wensheng Zhang

    E-print Network

    Zhang, Wensheng

    Sensor Relocation in Mobile Sensor Networks Guiling Wang, Guohong Cao, Tom La Porta, and Wensheng of research on using mobility in sensor networks to assist in the initial deployment of nodes. Mobile sensors. This paper explores the motion capability to relocate sensors to deal with sensor failure or respond to new

  13. On the data complexity of relative information completeness Yang Cao a,b

    E-print Network

    Antwerpen, Universiteit

    On the data complexity of relative information completeness Yang Cao a,b , Ting Deng b,n , Wenfei Fan a,b , Floris Geerts c a School of Informatics, University of Edinburgh, 10 Crichton Street XueYuan Road, Haidian District, Beijing, China c Department of Mathematics and Computer Science

  14. Strain effects in low-dimensional transition metal oxides Jinbo Cao a,b,

    E-print Network

    Wu, Junqiao

    Strain effects in low-dimensional transition metal oxides Jinbo Cao a,b, *, Junqiao Wu a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 1.1. Spin­lattice­charge coupling in transition metal oxides/nanowires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 3.2. Phase transitions and domain physics under strain

  15. Brownian motion in dynamically disordered media James B. Witkoskie, Shilong Yang, and Jianshu Cao*

    E-print Network

    Cao, Jianshu

    Brownian motion in dynamically disordered media James B. Witkoskie, Shilong Yang, and Jianshu Cao April 2002; revised manuscript received 12 August 2002; published 26 November 2002 The motion of Brownian test particles in a model random potential with time dependent correlations is investigated using

  16. Organic cosolvents and hen egg white lysozyme folding Bing Lai, Aoneng Cao, Luhua Lai *

    E-print Network

    Luhua, Lai

    Organic cosolvents and hen egg white lysozyme folding Bing Lai, Aoneng Cao, Luhua Lai * State Key July 2000; accepted 3 August 2000 Abstract Studies on the influence of organic cosolvents on lysozyme soluble organic cosolvents on hen egg white lysozyme heat induced denaturation and refolding dynamics

  17. Synthesis and Electrochemical Properties of V2O5 Nanostructures Ying Wang and Guozhong Cao*

    E-print Network

    Cao, Guozhong

    by Fontenot et al. [11] with V2O5 (Alfa Aesar) and 30% H2O2 (J.T.Baker) as precursors. Applied voltage was 0Synthesis and Electrochemical Properties of V2O5 Nanostructures Ying Wang and Guozhong Cao synthesis and template-based electrodeposition. Processing, morphology, structure and electrochemical

  18. Developing Actionable Trading Strategies for Trading Agents Longbing Cao, Chao Luo, Chengqi Zhang

    E-print Network

    Cao, Longbing

    Developing Actionable Trading Strategies for Trading Agents Longbing Cao, Chao Luo, Chengqi Zhang,chengqi}@it.uts.edu.au Abstract Trading agents are very useful for developing and back- testing quality trading strategies for actions taking in the real world. However, the existing trading agent research mainly focuses

  19. Studies on additives of high-temperature CaO sulfation

    SciTech Connect

    Fan, H.; Zhang, M.; Yao, Q.; Cao, X.; Cen, K.

    1999-07-01

    It is known that FSI (Furnace Sorbent Injection) is a kind of simple method for SO{sub 2} control. However, SO{sub 2} removal efficiency is low because of low sorbent utilization efficiency. In this paper, additives of CaO sulfation were studied. Through experiments, it can be found that some alkaline-metal compounds (NaCl, etc) and Al{sub 2}O{sub 3} can enhance CaO sulfation. The removal efficiencies can reach 89%(NaCl) and 78%(Al{sub 2}O{sub 3}) respectively at Ca/S=1.6. Meanwhile, the results also show that, compared with alkaline-metal compounds, Al{sub 2}O{sub 3} is more effective in high-temperature zone. Through SEM and X-ray diffraction analyses, the mechanism is thought as the follows: alkaline-metal compounds can change microstructure of CaO, and Al{sub 2}O{sub 3} can make stable product (3CaO {sm{underscore}bullet} 3Al{sub 2}O{sub 3} {sm{underscore}bullet} CaSO{sub 4}) formed in high-temperature desulfurization process.

  20. The Informational Content of an Open Limit Order Book Charles Cao Oliver Hansch Xiaoxin Wang

    E-print Network

    Kearns, Michael

    The Informational Content of an Open Limit Order Book Charles Cao Oliver Hansch Xiaoxin Wang June Informational Content of an Open Limit Order Book Abstract We assess the informational content of an open limit order book from three directions: (1) Does the limit order book allow better inferences about a security

  1. Testing Service Composition Using TGSE tool Tien-Dung Cao 1

    E-print Network

    Paris-Sud XI, Université de

    Testing Service Composition Using TGSE tool Tien-Dung Cao 1 , Patrick F´elix 1 , Richard Castanet 1 Rochelle, France. Email: ismail.berrada@univ-lr.fr Abstract This paper proposes an approach to test (actively and passively) a Web service composition described in BPEL using the TGSE (Test Generation

  2. Quantum control of dissipative systems: Exact solutions Jianshu Cao, Michael Messina, and Kent R. Wilson

    E-print Network

    Cao, Jianshu

    t HM Hint , 1.2 where the molecular term is HM Hg g g He e e and the interaction term is Hint E(t) g eQuantum control of dissipative systems: Exact solutions Jianshu Cao, Michael Messina, and Kent R. Wilson Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla

  3. Agent-Based Grid Load Balancing Using Performance-Driven Task Scheduling Junwei Cao*1

    E-print Network

    Jarvis, Stephen

    Agent-Based Grid Load Balancing Using Performance-Driven Task Scheduling Junwei Cao*1 , Daniel P This work was carried out when the author was with the University of Warwick. Abstract Load balancing-driven task scheduler that has been developed for local grid load balancing. Each grid scheduler utilises

  4. A Data Stream Outlier Delection Algorithm Based On Reverse K Nearest Neighbors Cao Lijun 1

    E-print Network

    Morik, Katharina

    capture the phenomenon of concept drift of data stream in time. Results of experiments conducted on bothA Data Stream Outlier Delection Algorithm Based On Reverse K Nearest Neighbors Cao Lijun 1 , Liu-MAIL:Misscao6666@163.com, liuxiyin2003@sina.com, zamjam99@yahoo.cn Abstract--A new data stream outlier detection

  5. Evaluation of biological cell properties using dynamic indentation measurement Guoxin Cao* and Namas Chandra

    E-print Network

    Farritor, Shane

    Evaluation of biological cell properties using dynamic indentation measurement Guoxin Cao February 2010 Viscoelastic mechanical properties of biological cells are commonly measured using atomic on numerical simulation is built to determine the cell mechanical properties. It is shown that the existing

  6. Making Routers Last Longer with ViAggre Hitesh Ballani, Paul Francis, Tuan Cao and Jia

    E-print Network

    Greenberg, Albert

    Making Routers Last Longer with ViAggre Hitesh Ballani, Paul Francis, Tuan Cao and Jia Wang Cornell deployment Routing Table stored in Forwarding Information Base (FIB) on Routers Large Routing Table More FIB space on Routers #12;Does FIB Size Matter? The problem is Scaling Properties of FIB memory (low volume

  7. Context-Dependent Term Relations for Information Retrieval Jing Bai Jian-Yun Nie Guihong Cao

    E-print Network

    Nie, Jian-Yun

    Context-Dependent Term Relations for Information Retrieval Jing Bai Jian-Yun Nie Guihong Cao DIRO,nie,caogui}@iro.umontreal.ca Abstract Co-occurrence analysis has been used to determine related words or terms in many NLP-related applications such as query expansion in Information Retrieval (IR). However, related words are usually

  8. ANNUAL TREE GROWTH PREDICTIONS FROM PERIODIC MEASUREMENTS Quang V. Cao1

    E-print Network

    Cao, Quang V.

    ANNUAL TREE GROWTH PREDICTIONS FROM PERIODIC MEASUREMENTS Quang V. Cao1 Abstract--Data from annual techniques were employed to model annual changes of individual trees in terms of diameters, heights used to fit the same tree growth equations. Two methods of estimating parameters of the annual growth

  9. Modelling Business Energy Consumption using Agent-based Simulation Modelling Jason Wong and Kay Cao1

    E-print Network

    Modelling Business Energy Consumption using Agent-based Simulation Modelling Jason Wong and Kay Cao to estimate business energy consumption taking into account business decision-making process in responding feasibility. I. Introduction Current modelling techniques employed for deriving non-survey energy consumption

  10. Multi-GPU Load Balancing for In-situ Visualization R. Hagan and Y. Cao

    E-print Network

    Cao, Yong

    Multi-GPU Load Balancing for In-situ Visualization R. Hagan and Y. Cao Department of Computer simulations. Multi-GPU computing, on the other hand, allows concurrent computation of simulation and rendering that decreases utilization and performance. This work proposes load balancing for in-situ visualization

  11. Coupled Attribute Analysis on Numerical Data Can Wang, Zhong She, Longbing Cao

    E-print Network

    Cao, Longbing

    Coupled Attribute Analysis on Numerical Data Can Wang, Zhong She, Longbing Cao Advanced Analytics. This paper proposes a framework of the coupled at- tribute analysis to capture the global dependency and coupled via explicit or implicit relationships. Limited re- search has been conducted on analyzing such at

  12. Linear theory for optimal control of molecular wave packets Jianshu Cao and Kent R. Wilson

    E-print Network

    Cao, Jianshu

    Linear theory for optimal control of molecular wave packets Jianshu Cao and Kent R. Wilson-0339 Received 14 August 1996 A linear theory for optimizing optical fields to achieve a molecular configuration wave packets used by Averbukh and Shapiro Phys. Rev. A 47, 5086 1993 . A numerical example

  13. Semimicro chemical and x-ray fluorescence analysis of lunar samples

    USGS Publications Warehouse

    Rose, H.J., Jr.; Cuttitta, F.; Dwornik, E.J.; Carron, M.K.; Christian, R.P.; Lindsay, J.R.; Ligon, D.T.; Larson, R.R.

    1970-01-01

    Major and selected minor elements were determined in seven whole rock fragments, five portions of pulverized lunar rock, and the lunar soil. Three different rock types were represented: vesicular, fine-grained basaltic rocks; medium-to coarse-grained, vuggy gabbroic rocks; and breccia. The ranges (in percent) for the major constituents of the lunar samples are: SiO2, 38 to 42; Al2O3, 8 to 14; total iron as FeO, 15 to 20; MgO, 6 to 8; CaO, 10 to 12; Na2O, 0.5 to 1; K2O, 0.05 to 0.4; TiO2, 8 to 13; MnO, 0.2 to 0.3; and Cr2O3, 0.2 to 0.4. The high reducing capacity of the samples strongly suggests the presence of Ti(III).

  14. Major and trace elements in igneous rocks from Apollo 15.

    NASA Technical Reports Server (NTRS)

    Helmke, P. A.; Blanchard, D. P.; Haskin, L. A.; Telander, K.; Weiss, C.; Jacobs, J. W.

    1973-01-01

    The concentrations of major and trace elements have been determined in igneous rocks from Apollo 15. All materials analyzed have typical depletions of Eu except for minerals separated from sample 15085. Four samples have concentrations of trace elements that are similar to those of KREEP. The samples of mare basalt from Apollo 15 have higher concentrations of FeO, MgO, Mn, and Cr and lower concentrations of CaO, Na2O, K2O, and rare-earth elements (REE) as compared to the samples of mare basalt from Apollos 11, 12, and 14. The samples can be divided into two groups on the basis of their normative compositions. One group is quartz normative and has low concentrations of FeO while the other is olivine normative and has high concentrations of FeO. The trace element data indicate that the samples of olivine normative basalt could be from different portions of a single lava flow.

  15. Antibacterial glass-composite coatings for protection of special purpose steel panels

    NASA Astrophysics Data System (ADS)

    Savvova, O.; Bragina, L.; Babich, E.

    2011-12-01

    It has been established that the most informative and universal method for determination of biocide properties of vitreous coatings is qualitative method that takes into account the growth level of biotest microorganisms inoculated into liquid nutrient media. It is shown, that biocidity of glass-composite coatings on the basis of glasses of Na2O - K2O - CaO - ZrO2 - TiO2 - Al2O3 - P2O5 - B2O3 - SiO2 system is determined by the presence of calcium phosphates in them and depends on the type of bactericide filler. The most effective ones by the action on Pseudomonas aeruginosa bacterium and Aspergillus niger and Candida albicans fungi are zinc titanate and Ag+, to Escherichia coli- only zinc phosphate.

  16. Biomineral nanostructures of manganese oxides in oceanic ferromanganese nodules

    NASA Astrophysics Data System (ADS)

    Lysyuk, G. N.

    2008-12-01

    Manganese oxides, which are widespread and of great practical importance, are formed and transformed by the active role of microorganisms. Manganese aggregates occur as both crystallized varieties and disordered fine-grained phases with significant ore grade and up to 50-60 vol % of X-ray amorphous components. X-ray amorphous nanosized Mn oxides in Fe-Mn nodules from the Pacific Ocean floor were examined from the standpoint of their biogenic origin. SEM examination showed abundant mineralized biofilms on the studied samples. The chemical composition of bacterial mass is as follows (wt %): 28.34 MnO, 17.14 Fe2O3, 7.11 SiO2, 2.41 CaO, 17.90 TiO2, 1.74 Na2O, 1.73 Al2O3, 1.30 MgO, 1.25 P2O5, 1.25 SO3, 0.68 CoO, 0.54 CuO, 0.53 NiO, and 0.50 K2O. The chemical composition of fossilized cyanobacterial mats within the interlayer space of nodulesis as follows (wt %): 48.35 MnO, 6.23 Fe2O3, 8.76 MgO, 5.05 Al2O3, 4.45 SiO2, 3.63 NiO, 2.30 Na2O, 2.19 CuO, 1.31 CaO, and 0.68 K2O is direct evidence for participation of bacteria in Mn oxide formation. This phase consists of mineralized glycocalix consisting of nanosized flakes of todorokite. Native metals (Cu, Fe, and Zn) as inclusions 10-20 ?m in size were identified in ferromanganese nodules as well. The formation of nativemetals can be explained by their crystallization at highly reducing conditions maintained by organic matter.

  17. Biomineral microstructures in ferromanganese nodules: evidence of the biological and abiogenous origin

    NASA Astrophysics Data System (ADS)

    Lysyuk, G. N.

    2011-10-01

    Manganese oxides, which are widespread and of great practical importance, are formed and transformed by the active role of microorganisms. Manganese aggregates occur as both crystallized varieties and disordered fine-grained phases with significant ore grade and up to 50-60 vol % of X-ray amorphous components. X-ray amorphous nanosizedMn oxides in Fe-Mn nodules from the Pacific Ocean floor were examined from the standpoint of their biogenic origin. SEM examination showed abundant mineralized biofilms on the studied samples. The chemical composition of bacterial mass is as follows (wt %): 28.34 MnO, 17.14 Fe2O3, 7.11 SiO2, 2.41 CaO, 17.90 TiO2, 1.74Na2O,1.73 A12O3,1.30 MgO, 1.25P2O5,1.25 SO3,0.68 CoO, 0.54 CuO, 0.53 NiO, and 0.50 K2O. The chemical composition of fossilized cyanobacterial mats within the interlayer space of nodules is as follows (wt %): 48.35 MnO, 6.23 Fe2O3, 8.76 MgO, 5.05 A12O3, 4.45 SiO2, 3.63 NiO, 2.30 Na2O, 2.19 CuO, 1.31 CaO, and 0.68 K2O is direct evidence for participation of bacteria in Mn oxide formation. This phase consists of mineralized glycocalix consisting of nanosized flakes of todorokite. Native metals (Cu, Fe, and Zn) as inclusions 10-20 ?m in size were identified in ferromanganese nodules as well. The formation of native metals can be explained by their crystallization at highly reducing conditions maintained by organic matter.

  18. Materials compatibility during the chlorination of molten CaCl/sub 2/. CaO salts. [CaCl/sub 2/. CaO salt

    SciTech Connect

    Rense, C.E.C.; Fife, K.W.; Bowersox, D.F.; Ferran, M.D.

    1987-01-01

    As part of our effort to develop a semicontinuous PuO/sub 2/ reduction process, we are investigating promising materials for containing a 900/sup 0/C molten CaCl/sub 2/ . CaO chlorination reaction. We want the material to contain this reaction and to be reusable. We tested candidate materials in a simulated salt (no plutonium) using anhydrous HCl as the chlorinating agent. Data are presented on the performance of 36 metals and alloys, 9 ceramics, and 3 coatings.

  19. GPU Accelerated Fuzzy Connected Image Segmentation by using CUDA Ying Zhuge, Yong Cao, Jayaram K. Udupa, and Robert W. Miller

    E-print Network

    Cao, Yong

    ], upper airway segmentation in children via MRI for studying obstructive sleep apnea [6], electron {zhugey, rwmiller}@mail.nih.gov Yong Cao is with Computer Science Department, Virginia Poly- technic

  20. Ruben Armiana Chair; President, SSU Andrew Rogerson Co-Chair; Provost, CAO and Vice President for Academic Affairs

    E-print Network

    Ravikumar, B.

    Ruben Armiñana Chair; President, SSU Andrew Rogerson Co-Chair; Provost, CAO and Vice President for University Affairs Matthew Lopez-Phillips Chief Student Affairs Officer Erik Greeny Interim Vice President

  1. Modéles de lignes simples et couplées, idéales et à pertes, pour la CAO des circuits gigabits

    Microsoft Academic Search

    Arimyaou Zounon; Paul Crozat; Robert Adde

    1990-01-01

    Résumé  Cet article expose les principes de conception d’une bibliothéque de modéles de lignes simples et couplées, idéales et à pertes,\\u000a pour la cao des circuits gigabits. Les modèles sont basés sur une description des lignes, dans le cadre de l’approximation\\u000a quasi-TEM, qui utilise la méthode des ondes mobiles et la simulation directe dans le domaine temporel pour des raisons de

  2. Breathing shell model in molecular dynamics simulation: Application to MgO and CaO

    Microsoft Academic Search

    Masanori Matsui

    1998-01-01

    Molecular dynamics (MD) simulation is used to calculate the elastic constants of both MgO and CaO at zero pressure, and their temperature dependences, as well as the temperature-pressure-volume equation of states of the two oxides. The interionic potential is taken to be the sum of pairwise additive Coulomb, van der Waals, and repulsive interactions. In order to account for the

  3. Treatability of PCB-contaminated soils with quicklime (CaO)

    Microsoft Academic Search

    D. Mauro; B. B. Taylor

    1992-01-01

    The possibility that quicklime (calcium oxide, CaO) can destroy PCBs has received much attention over the past year. Observations at an EPA remediation site, where lime-containing kiln dusts were used for interim stabilization of PCB-containing wastes prompted the EPA to sponsor a small research project to investigate quicklime-PCB interactions. That study reported decreases in PCB content in synthetic, PCB-spiked soil

  4. The CaO distribution to mineral phases in a high calcium fly ash from Eastern Germany

    SciTech Connect

    Enders, M. [WWU, Muenster (Germany)] [WWU, Muenster (Germany)

    1996-02-01

    High Calcium Fly Ashes (HCFA) are increasingly important as an admixture to mortar and concrete. The reactivity of HCFA is related to mineral phases like free lime, glassy spheres, anhydrite and yee`liminite. The occurrence of CaO in several crystalline phases and at least one non-crystalline mineral phase complicates the quantification of any of those mineral phases. This study focuses on a direct assessment of free lime and an indirect method for determination of CaO bounded in glassy spheres and anhydrite. CaO is enriched in fine particle size ranges. Glassy spheres are the most important CaO bearing mineral phase in the examined HCFA. The maximum CaO content bound in a glassy matrix is close to the composition of anorthite (<25 wt%). This is probably due to the restricted solubility of chemical species in a cooling melt of anorthitic composition. At the end of the high temperature process an equilibrium is attained between free lime, anhydrite and glassy spheres. The distribution of CaO among mineral phases is controlled by the availability of SO{sub 3} and free lime.

  5. Development of CaO coatings by thermal and chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Natesan, K.; Uz, M.; Smith, D. L.

    2002-12-01

    We conducted several experiments to test electrically insulating CaO coatings on a V-4Cr-4Ti alloy for application in the Li environment of liquid metal blankets in fusion reactors. Two processes that involve double Ca deposition/oxidation steps were developed to successfully coat V-4Cr-4Ti alloy samples with stable CaO. During the study, we examined several geometrical arrangements, using tabs and/or rod specimens. After Ca deposition from the vapor phase, the specimens were oxidized in an Ar-10 vppm O 2 environment at ?600 °C to convert the deposited metal into oxide, whereupon they exhibited insulating characteristics. Several coated specimens were then exposed to Li-2.8 at.%Ca at 500-700 °C to determine chemical compatibility and mechanical integrity. Depth profile analysis of the coatings was conducted to evaluate the compositional changes in the coatings and to assess the transport, if any, of substrate and coating constituents. Microstructural characteristics of the coatings were evaluated by scanning electron microscopy. The preliminary results indicate that CaO is a viable coating for V-Li advanced blankets.

  6. Interfacial Phenomena among Liquid Iron-Carbon Alloy, Liquid Slag, and Solid CaO

    NASA Astrophysics Data System (ADS)

    Taniguchi, Yoshinori; Seetharaman, Seshadri

    2012-06-01

    Interfacial phenomena between hot metal, liquid slag and solid CaO are important to the understanding of the desulfurization reaction in hot-metal treatment processes. In the current work, the surface tension of molten iron-carbon alloy and liquid slag as well as the interfacial tensions among molten iron-carbon alloy-solid CaO, liquid slag-solid CaO, as well as molten iron-carbon alloy-liquid slag were measured in the temperature range 1623 K to 1723 K (1350 °C to 1450 °C). The sessile drop method has been used for these measurements. To analyze the experimental results, two types of graphical analysis programs have been developed to determine the coordinates of the X-ray shadow or charge-coupled device (CCD) image of the droplet. Furthermore, a software package that uses the Gauss-Newton method to minimize an error function between the physically observed and a theoretical Laplacian curve has also been developed in this work.

  7. An experimental approach to manufacturing technology of historical glass (XIII-XV centuries). Comparison with current glassmaking technology.

    NASA Astrophysics Data System (ADS)

    Tarrago, Mariona; Gimeno, Domingo; Bazzocchi, Flavia; Garcia-Valles, Maite; Martinez, Salvador

    2015-04-01

    One of the major and less explored issues in the characterization of historical glasses is the determination of their viscosity as a function of temperature in order to constrain technological aspects of glass production. Until now, assumptions on temperatures have been based on mathematical models based on chemical compositions. Hence, the topic of this work is to explore the technology of stained glass production related to the workability and melting process of the glass by experimental laboratory measurements. This work presents the analysis of viscosity of glasses from different historical sites and chemical compositions: four from Santes Creus (Tarragona, XIII century), two of classical medieval stained glass window from Santa Maria de Pedralbes (Barcelona, mid XIV century), and three of evolved late-medieval type from Santa Maria del Mar (Barcelona first half of XV century), and one sample of soda-lime industrial glass by means of Hot-Stage Microscopy and glass transformation temperature Tg by dilatometry. These data are then compared to the predictions on theoretical viscosity obtained from mathematical models based on chemical composition. These samples are classified according to their major modifier in: Na-rich (12-17% of Na2O, between 65-77% of SiO2 and less than 3 % of K2O); Ca-rich (29% of CaO, 54% of SiO2, 4% of K2O, and 4% of Na2O); K-Ca-rich (17 to 21% of K2O, more than 14% of CaO, 49-55% of SiO2and less than 2% of Na2O); Na-Ca-rich (12-14% of Na2O, 9-15% of CaO, 57-71% of SiO2 and < 6% of K2O). Glass transition temperature (Tg) is correlated to chemical composition: 464-492 °C for Na-rich, 645 °C for Ca-rich, 582-586 °C for K-Ca-rich and 497-542 °C for Na-Ca-rich glasses. Experimental viscosity-temperature curves are traced using Tg and fixed viscosity points measured by Hot-Stage microscopy (according to German standard 51730) in order to provide more accurate insight into the phases of glass production process (melting, working, conditioning and annealing ranges). These results are also compared to mathematical models of glass viscosity based on chemical composition. The annealing range (viscosity between 1013.5 and 1012 Pa-s) is reached at temperatures between 484-633°C (strain point) and 509-664°C (upper limit). The working point (viscosity of 103 Pa-s) has temperature values in the range between 958 and 1097°C.

  8. DUSTER: collection of meteoric CaO and carbon smoke particles in the upper stratosphere

    NASA Astrophysics Data System (ADS)

    Rietmeijer, F. J. M.; Della Corte, V.; Rotundi, A.; Ferrari, M.; Palumbo, P.

    2014-04-01

    Nanometer CaO and pure carbon smoke particles were collected at 38-km altitude in the upper stratosphere in the Arctic during June 2008 using DUSTER (Dust in the Upper Stratosphere Tracking Experiment and Retrieval), a balloon-borne instrument for the non-destructive collection of solid particles between 200 nm to 40 microns. We report the collection of micron sized CaCO3 (calcite) grains. Their morphologies show evidence of melting and condensation after vaporization suggest at temperatures of approximately 3500 K. The formation environment of the collected grains was probably a dense dust cloud formed by the disintegration of a carbonaceous meteoroid during deceleration in the Earth's atmosphere.

  9. Copyrighted (Textbook) Fei Hu and Xiaojun Cao, Wireless Sensor Networks: Principles and Practice, CRC Press Page 1 Chapter 3: Medium Access Control in

    E-print Network

    Hu, Fei

    , CRC Press Page 1 Chapter 3: Medium Access Control in Wireless Sensor Networks 3.1 Introduction;Copyrighted (Textbook) Fei Hu and Xiaojun Cao, Wireless Sensor Networks: Principles and Practice, CRC Press (Textbook) Fei Hu and Xiaojun Cao, Wireless Sensor Networks: Principles and Practice, CRC Press Page 3 power

  10. Copyrighted (Textbook) Fei Hu and Xiaojun Cao, Wireless Sensor Networks: Principles and Practice, CRC Press Page 1 Chapter 6: Operating System in Sensors

    E-print Network

    Hu, Fei

    , CRC Press Page 1 Chapter 6: Operating System in Sensors Although operating system (OS) is a typical;Copyrighted (Textbook) Fei Hu and Xiaojun Cao, Wireless Sensor Networks: Principles and Practice, CRC Press and Xiaojun Cao, Wireless Sensor Networks: Principles and Practice, CRC Press Page 3 event handler immediately

  11. Copyrighted (Textbook) Fei Hu and Xiaojun Cao, Wireless Sensor Networks: Principles and Practice, CRC Press Page 1 Chapter 5: Transport Layer in Wireless

    E-print Network

    Hu, Fei

    , CRC Press Page 1 Chapter 5: Transport Layer in Wireless Sensor Networks As we recall from general Cao, Wireless Sensor Networks: Principles and Practice, CRC Press Page 2 follows: [YIyer05] 1) Generic Cao, Wireless Sensor Networks: Principles and Practice, CRC Press Page 3 6) Scalability: Sensor

  12. Development of natural crude drug resources from Taiwan (X). Pharmacognostical studies on the Chinese crude drug "han-lian-cao".

    PubMed

    Chen, J Y; Lin, C C; Namba, T

    1992-01-01

    In a previous paper(1), it was reported that the drug "Han-lian-cao", in Taiwan was derived from the entire plant or aerial part of Eclipta prostrata L. and Alternanthera sessilis R. Brown. In this paper, the histological studies of "Han-lian-cao" derived from Wedelia and Hypericum plants, and of 3 species of Wedelia related plants distributed in Taiwan were made. The results showed that it was possible to classify these species by their external and internal characteristics. In addition, a key to the characteristics of the whole plants of Eclipta, Alternanthera, Wedelia and Hypericum plants are hereby given. PMID:1605130

  13. Self-healing of defects in CaO coatings on V-5%Cr-5%Ti in liquid lithium

    SciTech Connect

    Park, J.H.; Kassner, T.F.

    1994-11-01

    In-situ electrical resistance of CaO coatings produced on V-5%Cr-5%Ti by exposure of the alloy to liquid Li that contained 0.5-85 wt % dissolved Ca was measured as a function of time at temperatures between 250 and 600{degrees}C. Examination of the specimens after cooling to room temperature revealed no spallation, but homogeneous crazing cracks were present in the CaO coating. Additional tests to investigate the in-situ self-healing behavior of the cracks indicated that rapid healing occurred at >360{degrees}C.

  14. Calcium precursors for the production of CaO sorbents for multicycle CO2 capture.

    PubMed

    Liu, Wenqiang; Low, Nathanael W L; Feng, Bo; Wang, Guoxiong; Diniz da Costa, João C

    2010-01-15

    A screening of potential calcium precursors for the production of CaO sorbents for CO(2) capture at high temperature was conducted in this work. The precursors studied include microsized calcium carbonate (CC-CaO), calcium hydroxide (CH-CaO), nanosized (<70 nm) calcium carbonate (CC70 nm-CaO), nanosized (<160 nm) calcium oxide (CaO160 nm-CaO), calcium acetate hydrate (CA-CaO), calcium l-lactate hydrate (CL-CaO), calcium formate (CF-CaO), calcium citrate tetrahydrate (CCi-CaO), and calcium d-gluconate monohydrate (CG-CaO). The capture capability of these sorbents was investigated using a thermogravimetric analyzer (TGA) for multiple capture cycles. CG-CaO exhibited the best capacity for capturing CO(2) with a 1-min conversion of 65.9% and a 30-min conversion of 83.8% at the ninth cycle. Subsequently, a further parametric study was conducted to examine the effect of reaction conditions such as reaction temperature (550-750 degrees C) and CO(2) gas concentration (1-15%) on the capture capacity of CG-CaO. The sorbent CG-CaO also showed a much lower decomposition temperature and higher predicted residual conversion after prolonged cycles, compared with CC-CaO. PMID:20030311

  15. Comparison of experimental results from three dual fluidized bed test facilities capturing CO 2 with CaO

    Microsoft Academic Search

    Nuria Rodríguez; Mónica Alonso; Juan Carlos Abanades; Alexander Charitos; Craig Hawthorne; Günter Scheffknecht; Dennis Y. Lu; Edward J. Anthony

    2011-01-01

    Postcombustion CO2 capture technologies using CaO as a regenerable solid sorbent have emerged as a promising route to reduce the electricity penalty and the cost of CO2 capture from flue gases of both new and existing fossil fu elled power plants. Rapid progress is taking place in the understanding of these processes at different levels. However, experimental information, validating the

  16. Scalable and High Performance HPC Architecture with Optical Interconnects Zheng Cao, Roberto Proietti, and S.J.B. Yoo

    E-print Network

    Yoo, S. J. Ben

    Scalable and High Performance HPC Architecture with Optical Interconnects Zheng Cao, Roberto, California, 95616, USA, e-mail: sbyoo@ucdavis.edu Abstract: We propose a HPC architecture that overcomes I become one of the main limitations in scaling High Performance Computing (HPC) performance. 1) Chip

  17. Optimal pump-dump control: Linearization and symmetry relation YiJing Yan, Jianshu Cao,a)

    E-print Network

    Cao, Jianshu

    Optimal pump-dump control: Linearization and symmetry relation YiJing Yan, Jianshu Cao of phase-unlocked pump-dump fields in the control of pure state molecular systems in the weak response regime. The associated eigenvalues are further correlated to the yields of pump-dump control, thus

  18. PROOF OF CORRECTNESS OF THE DIGITAL DELAUNAY TRIANGULATION THANH-TUNG CAO, HERBERT EDELSBRUNNER, AND TIOW-SENG TAN

    E-print Network

    Tan, Tiow Seng

    PROOF OF CORRECTNESS OF THE DIGITAL DELAUNAY TRIANGULATION ALGORITHM THANH-TUNG CAO, HERBERT. This provides the proof of correctness for recently developed GPU algorithms that outperform traditional CPU algorithms for constructing two-dimensional Delaunay triangulations. Key words. Graphics processing unit, GPU

  19. OCAO Computer Refreshment Policy The NOAA CAO is responsible for budgeting and procuring all personal computers and other

    E-print Network

    6/20/2007 OCAO Computer Refreshment Policy Purpose: The NOAA CAO is responsible for budgeting and procuring all personal computers and other support computers used by OCAO staff. To facilitate adequate capital planning and clarify acquisition policies, the following Computer Refreshment Policy

  20. HALL: A Hierarchical All-to-All Optical Interconnect Architecture Zheng Cao, Roberto Proietti, and S.J.B. Yoo

    E-print Network

    Kolner, Brian H.

    HALL: A Hierarchical All-to-All Optical Interconnect Architecture Zheng Cao, Roberto Proietti propose a hierarchical all-to-all optical interconnection architecture that implements packet switching logic into a single chip as a system-on-a-chip. All-to-all communica- tion [4] is particularly important

  1. High rate compression of CAD meshes based on subdivision Compression de maillages CAO base sur la subdivision inverse

    E-print Network

    Dupont, Florent

    High rate compression of CAD meshes based on subdivision inversion Compression de maillages CAO. In this paper we present a new framework, based on subdivision surface approximation, for efficient compression after several subdivision steps, without artifacts or cracks, like traditional lossy compression schemes

  2. An Air Traffic Prediction Model based on Kernel Density Estimation Yi Cao,1 Lingsong Zhang,2 and Dengfeng Sun3

    E-print Network

    Sun, Dengfeng

    through sophisticated flight dynamics [1]. However, for the Air Traffic Control Sys- tem Command Center at an Air Route Traffic Control Center (simply denoted as Center hereafter) level [2]. It forecasts aircraftAn Air Traffic Prediction Model based on Kernel Density Estimation Yi Cao,1 Lingsong Zhang,2

  3. An Admission Control Scheme for QoS-Sensitive Cellular Networks Sunho Lim, Guohong Cao, and Chita R. Das

    E-print Network

    Lim, Sunho

    An Admission Control Scheme for QoS-Sensitive Cellular Networks Sunho Lim, Guohong Cao, and Chita R load is high. Therefore, admission control is an inte- gral part of the call management mechanism, PA 16802 Abstract--We propose an admission control scheme to guarantee a cer- tain level of QoS to on

  4. Hopping versus bulk conductivity in transparent oxides: 12CaO7Al2O3 J. E. Medvedevaa)

    E-print Network

    Medvedeva, Julia E.

    Hopping versus bulk conductivity in transparent oxides: 12CaO·7Al2O3 J. E. Medvedevaa) and A. J. This results in a transition from variable range-hopping behavior with a Coulomb gap in H-doped UV is provided by vari- able range hopping, while C12A7:2e- shows bulk conduc- tivity. In addition

  5. Making Routers Last Longer with ViAggre Hitesh Ballani, Paul Francis, Tuan Cao and Jia Wang

    E-print Network

    Keinan, Alon

    1 Making Routers Last Longer with ViAggre Hitesh Ballani, Paul Francis, Tuan Cao and Jia Wang), a "configuration-only" approach to shrinking the routing table on routers. ViAggre does not require any changes to router software and routing protocols and can be deployed independently and autonomously by any ISP. Vi

  6. A Robust Panel Extraction Method for Manga Xufang Pang, Ying Cao, Rynson W.H. Lau, and Antoni B. Chan

    E-print Network

    Lau, W. H. Nynson

    A Robust Panel Extraction Method for Manga Xufang Pang, Ying Cao, Rynson W.H. Lau, and Antoni B, au- tomatic panel extraction for manga, i.e., Japanese comics, can be especially challenging, largely. In this paper, we propose a ro- bust method for automatically extracting panels from digi- tal manga pages. Our

  7. Steam-Coal Gasification Using CaO and KOH for in Situ Carbon and Sulfur Capture

    E-print Network

    Litster, Shawn

    Steam-Coal Gasification Using CaO and KOH for in Situ Carbon and Sulfur Capture Nicholas S. SiefertO to capture carbon dioxide decreased roughly 2-4% per CaO-CaCO3 cycle. We also discuss an important with and without the addition of calcium oxide and potassium hydroxide as dual-functioning catalyst-capture agents

  8. Etude par frottement intrieur et impdance complexe d'une zircone calcie cubique ZrO2-CaO

    E-print Network

    Paris-Sud XI, Université de

    1979 Etude par frottement intérieur et impédance complexe d'une zircone calciée cubique ZrO2-CaO S échantillons monocristallins de zircone cubique stabilisée à la chaux. L'étude en fréquence des spectres partir des solutions solides de zircone soient très répandues, les aspects fondamentaux des propriétés de

  9. Agglomeration characteristics of river sand and wheat stalk ash mixture at high temperatures

    NASA Astrophysics Data System (ADS)

    Shang, Linlin; Li, Shiyuan; Lu, Qinggang

    2013-02-01

    The agglomeration characteristics of river sand and wheat stalk ash mixture at various temperatures are investigated using a muffle furnace. The surface structural changes, as well as the elemental makeup of the surface and cross-section of the agglomerates, are analyzed by polarized light microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX). Multi-phase equilibrium calculation is performed with FactSage in identifying the melting behavior of the river sand-wheat stalk ash mixture at high temperatures. No indication of agglomeration is detected below 850°C. At a temperature of 900-1000°C, however, obvious agglomeration is observed and the agglomerates solidify further as temperature increases. The presence of potassium and calcium enrichment causes the formation of a sticky sand surface that induces agglomeration. The main component of the agglomerate surface is K2O-CaO-SiO2, which melts at low temperatures. The formation of molten silicates causes particle cohesion. The main ingredient of the binding phase in the cross-section is K2O-SiO2-Na2O-Al2O3-CaO; the agglomeration is not the result of the melting behavior of wheat stalk ash itself but the comprehensive results of chemical reaction and the melting behavior at high temperatures. The multi-phase equilibrium calculations agree well with the experimental results.

  10. Micro-Raman and micro-XRF analysis of glass beads from the Chungde site, Taiwan

    NASA Astrophysics Data System (ADS)

    Liou, Y. S.; Wang, S. C.; Liu, Y. C.

    2014-12-01

    A large number of ancient glass beads dating back from Late Neolithic Age to early Historical Period (ca. 2300-400 BP) of Taiwan have been uncovered from archaeological sites. These glass beads with variant colors, shapes, and stylistics have long been considered to possess socio-cultural significance. Due to the color and chemical composition of glass bead might be determined by raw materials, fluxing agents, colorants, opacifiers and stabilizers. In addition, ancient glass beads are rare and precious, non-destructive analysis has been employed to decipher about the provenances, manufacturing techniques, and exchange/trade routes. In this work, micro-Raman spectroscopy and micro X-ray fluorescent spectrometer (?-XRF) were used to examine ten ancient glass beads excavated from the Chungde site, Hualien, Taiwan, dating back to 1500-800 BP, to unravel the mineralogical and chemical compositions. Micro Raman experimental results show that glass and anorthite glass are the main constituents accompanying with trace level of quartz, albite, siderite, ankerite, and amazonite. The Raman Index of Polymerization (Ip) indicate that the sintering temperature of the glass beads is in the range of 1000~1400°C. Furthermore, the chemical compositions are corresponding to the maximum stretching vibration peak wave number (?max Si-O Stretching) and the maximum bending vibration peak wave number (?max Si-O Bending), which are essentially consistent with that of the India-Pacific beads. The ?-XRF results indicate the presence of oxides including SiO2, Al2O3, Fe2O3, Na2O, K2O, CaO, MgO, SnO2, TiO2, CuO, etc., and could be classified to high aluminum of soda-lime glass system. According to ternary phase diagram analysis of CaO-K2O-Na2O and K2O-Al2O3-CaO, the ancient glass beads analyzed could be attributed to the India-Pacific beads, and is in accordance with that of Raman spectra. The combination of these facts leads to the conclusion that glass beads obtained from the Chungde site may be ascribed to the India-Pacific beads.

  11. Raman study on B 2O 3-CaO glasses

    NASA Astrophysics Data System (ADS)

    Maniu, D.; Iliescu, T.; Ardelean, I.; Cinta-Pinzaru, S.; Tarcea, N.; Kiefer, W.

    2003-06-01

    Glasses are of special interest nowadays mainly because of the large applications that they span. Raman spectroscopy is an experimental technique appropriate for providing information about the structure of local arrangements of the atoms in glasses. The influence of CaO content on the structure of borate glasses was investigated by Raman spectroscopy. At low calcium oxide content the structure of calcium borate glass consists mainly of boroxol groups and a smaller number of pentaborate groups. In the vitreous network there are few diborate groups, chain type metaborate groups and pyroborate groups. At high calcium oxide content, pentaborate, orthoborate and metaborate groups appear. The increase of calcium oxide content yields an increase in number of non-bridging oxygen ions. Therefore, we conclude that calcium ions act as network modifiers in borate glasses.

  12. The effect of composition on the viscosity, crystallization and dissolution of simple borate glasses and compositional design of borate based bioactive glasses

    NASA Astrophysics Data System (ADS)

    Goetschius, Kathryn Lynn

    Borate glasses have recently been developed for a variety of medical applications, but much less is known about their structures and properties than more common silicate glasses. Melt properties and crystallization tendency for compositions in the Na2O-CaO-B2O3 system were characterized using differential thermal analysis and viscosity measurements. Characteristic viscosity (isokom) temperatures varied with the ratio between the modifier content (Na2O+CaO) and B2O3, particularly at lower temperatures, consistent with the changes in the relative concentrations of tetrahedral borons in the glass structure. Similar glasses were used to study dissolution processes in water. These alkali-alkaline earth glasses dissolve congruently and follow linear dissolution kinetics. The dissolution rates were dependent on the glass structure, with slower rates associated with greater fractions of four-coordinated boron. For glasses with a fixed alkaline earth identity, the dissolution rates increased in the order LiNa2O, K2O, MgO, CaO, B2O3, SiO2, and P2O5) mixture model design was used to predict composition-property relationships to optimize the properties of new borate-based bioactive compositions for specific applications. Melt viscosity, thermal expansion coefficient, liquidus temperature and crystallization tendency were determined, as were dissolution rates in simulated body fluid (SBF).

  13. [11] A. Y. Cao, X. F. Zhang, C. L. Xu, J. Liang, D. H. Wu, B. Q. Wei, Appl. Surf. Sci. 2001, 181, 234.

    E-print Network

    Huang, Yanyi

    . Liu, G. Yu, C. Xu, J. Zhang, D. Zhu, J. Phys. Chem. B 2001, 105, 9422. [18] W. A. de Heer, W. S. Bacsa[11] A. Y. Cao, X. F. Zhang, C. L. Xu, J. Liang, D. H. Wu, B. Q. Wei, Appl. Surf. Sci. 2001, 181. 2003, 15, 1105. [13] S. Huang, A. H. W. Mau, Appl. Phys. Lett. 2003, 82, 796. [14] A. Y. Cao, B. Q. Wei

  14. Characterization of forest biodiversity in Western Amazon using CAO-VSWIR imaging spectroscopy

    NASA Astrophysics Data System (ADS)

    Féret, J.; Asner, G. P.

    2012-12-01

    Mapping canopy species richness is a key to the study and conservation of biological diversity in tropical forests, but to date, no reliable methods exist for operational biodiversity mapping of tropical regions. Airborne imaging spectroscopy has proven potential for the discrimination of canopy tree species, as a combination of high spectral and spatial resolution allows measurement of subtle spectral variations among individual tree crowns, corresponding to the chemical properties of the leaves in different species. We developed a method to estimate the Shannon diversity index, a popular biodiversity indicator, of a forest canopy from airborne spectral data by building upon the Spectral Variation Hypothesis, which relates biological diversity to spectral variability. We collected and analyzed hyperspectral data acquired by the Carnegie Airborne Observatory (CAO) Airborne Taxonomic Mapping System (AToMS) over the Los Amigos Conservation Concession in the Peruvian Amazon. The data have a spatial resolution of 2.0 m and 217 bands evenly spaced between 380 nm and 2510 nm. The method relies on a k-means clustering of a subset of pixels randomly selected from a site, each cluster serving as a proxy for different species. Each pixel in the image is then assigned to the nearest 'proxy-species', the Shannon index is computed for a given area, i.e. 1 ha, and the process is repeated several times to obtain the average estimated Shannon index. To test our approach, we applied the method to two types of data acquired by CAO AToMS. The first was an artificial gradient of biological diversity generated using pixels corresponding to species identified during a field campaign. This artificial gradient allowed total control on the number of species (ranging from 1 to 36 species per ha), and accurate quantification of the results. The spectral diversity index mapped using our method showed a strong correlation with the actual Shannon diversity index (R^2=0.81). The second dataset was a 2000 ha mapped area covering patches of primary and secondary forests and logging areas, resulting in a large range of Shannon index values. The assessed values on this second dataset also proved correlated with field measurements, and additional field measurements are currently being collected for validation. The method developed here is computationally efficient and reliable when processing large areas. Future directions include applications to watershed and regional scales, which will provide important inputs for tropical forest conservation and management.

  15. Fingerprint methods for suspended sediment transport processes by using X-ray fluorescence analysis

    NASA Astrophysics Data System (ADS)

    Nakayama, K.; Beitia, C.; Ohtsu, N.; Yamasaki, S.; Yasuyuki, M.; Yamane, M.

    2014-12-01

    Suspended sediment (SS) can have significant impacts on ecological system, and high SS concentration can have significant impacts on human life. In the previous studies, radionuclide analysis has been applied to evaluate the production of SS in the river basins, which demonstrated that the surface soil erosion can be estimated by using radionuclide Pb-210ex. However, radionuclide analysis cannot indicate the relative amounts of SS transported from each individual sub-basin to the downstream end. Thus, X-ray Fluorescence Analysis (XRF Analysis) can be considered as an alternative method to radionuclide analysis because the XRF Analysis can measure 21 chemical compositions, Na2O, MgO, Al2O3, SiO2, P2O5, SO3, Cl, K2O, CaO, TiO2, Cr2O3, MnO, Fe2O3, Co2O3, NiO, CuO, ZnO, Rb2O, SrO, BaO, and Y2O3 by using X-ray Fluorescence Analyzer. In June of 2007, high turbidity, which is more than 10,000 (NTU), was measured in the Oromushi River basin of Hokkaido in Japan. Therefore, this study aims to clarify the mechanism of the transport of SS in the Oromushi River basin. We measured chemical compositions of soil with diameter less than 63 ?m in the Oromushi River basin in order to pay attention to SS by using XRF. The Principal Component Analysis revealed that SiO2, Al2O3, Fe2O3, CaO and Na2O are the dominant chemical compositions. Although the predominant composition was the same in a river basin including the downstream end, significant differences were found in the pattern of chemical compositions. Therefore, by using the chemical compositions of SiO2, Al2O3, Fe2O3, CaO and Na2O, the Mixing Stable Isotope Analysis in R model (MixSIAR) based on Bayesian statistics was applied to estimate the transportation rate of SS from each sub-basin to the downstream end, which agreed with the field experiment results very well. As a result, spatial patterns of SS transportation rate are found to be strongly related to surface soil type.

  16. Periodic Hartree-Fock study of B1 &rlhar2; B2 reactions: phase transition in CaO

    Microsoft Academic Search

    Philippe D'Arco; Luc-Henri Jolly; Bernard Silvi

    1992-01-01

    The periodic Hartree-Fock method has been used to sample the potential energy hypersurface of CaO to determine a collective reaction pathway between the low-pressure (NaCl) and high-pressure (CsCl) phases. The predicted transition pressure, 68 GPa, is in good agreement with both experimental data and previous theoretical studies. At low pressure the enthalpy (E + PV) surface presents only one minimum

  17. Fabrication of room temperature-stable 12CaO · 7Al 2 O 3 electride: a review

    Microsoft Academic Search

    Sung-Wng Kim; Satoru Matsuishi; Masashi Miyakawa; Katsuro Hayashi; Masahiro Hirano; Hideo Hosono

    2007-01-01

    12CaO · 7Al2O3 (C12A7) electride, which is synthesized by replacing free oxygen ions in cages with electron anions, has distinct advantages\\u000a over electrides reported so far in respect of thermal and chemical stability and flexible preparation of various sample forms\\u000a including single crystal, thin film, polycrystalline bulk and powder. These advantages, together with the fact that the concentration\\u000a of the electron anions

  18. Heat recovery from a thermal energy storage based on the Ca(OH) 2\\/CaO cycle

    Microsoft Academic Search

    M. N. Azpiazu; J. M. Morquillas; A. Vazquez

    2003-01-01

    Thermal energy storage is very important in many applications related to the use of waste heat from industrial processes, renewable energies or from other sources. Thermochemical storage is very interesting for long-term storage as it can be carried out at room temperature with no energy losses.Dehydration\\/hydration cycle of Ca(OH)2\\/CaO has been applied for thermal energy storage in two types of

  19. Micelle-Assisted Synthesis of Al2O3·CaO Nanocatalyst: Optical Properties and Their Applications in Photodegradation of 2,4,6-Trinitrophenol

    PubMed Central

    Imtiaz, Ayesha; Khaleeq-ur-rahman, Muhammad; Adnan, Rohana

    2013-01-01

    Calcium oxide (CaO) nanoparticles are known to exhibit unique property due to their high adsorption capacity and good catalytic activity. In this work the CaO nanocatalysts were prepared by hydrothermal method using anionic surfactant, sodium dodecyl sulphate (SDS), as a templating agent. The as-synthesized nanocatalysts were further used as substrate for the synthesis of alumina doped calcium oxide (Al2O3·CaO) nanocatalysts via deposition-precipitation method at the isoelectric point of CaO. The Al2O3·CaO nanocatalysts were characterized by FTIR, XRD, TGA, TEM, and FESEM techniques. The catalytic efficiencies of these nanocatalysts were studied for the photodegradation of 2,4,6-trinitrophenol (2,4,6-TNP), which is an industrial pollutant, spectrophotometrically. The effect of surfactant and temperature on size of nanocatalysts was also studied. The smallest particle size and highest percentage of degradation were observed at critical micelle concentration of the surfactant. The direct optical band gap of the Al2O3·CaO nanocatalyst was found as 3.3?eV. PMID:24311980

  20. Micelle-assisted synthesis of Al2O3·CaO nanocatalyst: optical properties and their applications in photodegradation of 2,4,6-trinitrophenol.

    PubMed

    Imtiaz, Ayesha; Farrukh, Muhammad Akhyar; Khaleeq-ur-rahman, Muhammad; Adnan, Rohana

    2013-01-01

    Calcium oxide (CaO) nanoparticles are known to exhibit unique property due to their high adsorption capacity and good catalytic activity. In this work the CaO nanocatalysts were prepared by hydrothermal method using anionic surfactant, sodium dodecyl sulphate (SDS), as a templating agent. The as-synthesized nanocatalysts were further used as substrate for the synthesis of alumina doped calcium oxide (Al2O3·CaO) nanocatalysts via deposition-precipitation method at the isoelectric point of CaO. The Al2O3·CaO nanocatalysts were characterized by FTIR, XRD, TGA, TEM, and FESEM techniques. The catalytic efficiencies of these nanocatalysts were studied for the photodegradation of 2,4,6-trinitrophenol (2,4,6-TNP), which is an industrial pollutant, spectrophotometrically. The effect of surfactant and temperature on size of nanocatalysts was also studied. The smallest particle size and highest percentage of degradation were observed at critical micelle concentration of the surfactant. The direct optical band gap of the Al2O3·CaO nanocatalyst was found as 3.3?eV. PMID:24311980

  1. Li/Mo codoping of CaO films: a means to tailor the equilibrium shape of Au deposits.

    PubMed

    Shao, Xiang; Nilius, Niklas; Freund, Hans-Joachim

    2012-02-01

    Using scanning tunneling microscopy, we have investigated how the doping of CaO thin films affects the growth behavior of gold. Whereas 3D deposits develop on pristine films, 2D islands form after inserting 4% of Mo into the CaO lattice. Adding small amounts of Li to the Mo-doped CaO reinstalls the initial 3D growth regime. We assign this morphology crossover to charge transfer processes between the dopants and the ad-metal. Whereas Mo acts as an electron donor and provides excess charges to be transferred into the gold, Li creates electron traps in the oxide lattice that interrupt the charge flow toward the metal. The different Au charge states in the presence of the dopants are derived from different growth morphologies with anionic gold favoring a 2D mode due to an enhanced interface adhesion. Our work demonstrates how oxide doping can be exploited to tailor the equilibrium geometry of ad-particles on supported metal catalysts. PMID:22280016

  2. CaO insulator coatings and self-healing of defects on V-Cr-Ti alloys in liquid lithium

    SciTech Connect

    Park, J.H.; Kassner, T.F.

    1996-02-01

    Electrically insulating and corrosion-resistant coatings are required at the liquid metal/structural interface in fusion first-wall/blanket applications. The electrical resistance of CaO coatings produced on V-5%Cr-5%Ti by exposure of the alloy to liquid Li that contained 0.5--85 wt.% dissolved Ca was measured as a function of time at temperatures between 250 and 600{degrees}C. The solute element, Ca in liquid Li, reacted with the alloy substrate at 400--420{degrees}C to produce a CaO coating. Resistance of the coating layer measured in-situ in liquid Li was {approx}10{sup 6} {Omega} at 400{degrees}C. Thermal cycling between 300 and 700{degrees}C changed the coating layer resistance. which followed insulator behavior. These results suggest that thin homogeneous coatings can be produced on variously shaped surfaces by controlling the exposure time, temperature, and composition of the liquid metal. The technique can be applied to various shapes(e.g., inside/outside of tubes, complex geometrical shapes) because the coating is formed by liquid-phase reaction. Examination of the specimens after cooling to room temperature revealed no spallation, but homogeneous crazing cracks were present in the CaO coating. Additional tests to investigate the in-situ self-healing behavior of the cracks indicated that rapid healing occurred at {ge}360{degrees}C.

  3. [Determination of multi-element contents in gypsum by ICP-AES].

    PubMed

    Guo, Zhong-bao; Bai, Yong-zhi; Cui, Jin-hua; Mei, Yi-fei; Ma, Zhen-zhu

    2014-08-01

    The content of multi-element in gypsum was determined by ICP-AES. The sample was pretreated by acid-soluble method or alkali-fusion method. Acid-soluble method is suitable for the determination of CaO, SOs, Al2O3, Fe2O3, MgO, K2O, Na2O, TiO2, P2O5, MnO, SrO and BaO. Alkali-fusion method is suitable for the determination of CaO, SO3, SiO2, Al2O3, Fe2O3, MgO, TiO2, P2O5, MnO, SrO, BaO and B2O3. Different series standard solutions were prepared considering the properties and content of elements and solution matrix. The limit of detection and quantification were confirmed for each element under their best analysis spectral lines. The recoveries of the two pretreatment methods were from 93% to 110%, besides that for TiO2 was 81%-87% as pretreated by acid-soluble method. All RSDs (n=6) of tests were from 0.70%-3.42%. The accuracies of CaO and SO3 with ICP-AES method were less than the chemical analysis method. The determination of CaO and SO3 with ICP-AES method is only suitable for the case of low accuracy requirement. The results showed that the method can be used for the determination of multi-element contents in gypsum, with simple operation, fast analysis and reliable results. Total elements can be analysed with both acid-soluble method and alkali-fusion method. PMID:25508750

  4. Alkali activation of fly ash: Effect of the SiO 2\\/Na 2O ratio

    Microsoft Academic Search

    M. Criado; A. Fernández-Jiménez; A. Palomo

    2007-01-01

    In this paper the main reaction products formed in alkali activated fly ash systems have been studied by using Infrared Spectroscopy. The main variables of work were: soluble silica content in the alkaline activating solution (0% SiO2; 1.62% SiO2; 5.40% SiO2 and 9.07% SiO2) and thermal curing time (8h, 60 and 180 days). The results obtained have shown that the

  5. Materials Data on Na2O2 (SG:189) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  6. Materials Data on Na2O2 (SG:189) by Materials Project

    DOE Data Explorer

    Kristin Persson

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  7. Boroaluminosilicate glasses as ion exchange materials

    Microsoft Academic Search

    Jayshree Ramkumar; S. Chandramouleeswaran; V. Sudarsan; R. K. Vatsa; S. Shobha; V. K. Shrikhande; G. P. Kothiyal; T. Mukherjee

    2010-01-01

    Sodium boroaluminosilicate glasses, (Na2O)0.22(K2O)0.029(B2O3)0.05(SiO2)0.69(Al2O3)0.011 and (Na2O)0.05(K2O)0.029(B2O3)0.22(SiO2)0.69(Al2O3)0.011 having different B2O3 to Na2O mole ratio of 0.23 and 4.4 respectively were investigated for their uptake characteristics of cationic dyes, namely Rhodamine 6G and methylene blue, from aqueous solutions. Both the glasses have been found to adsorb these dyes. However, the glass with B2O3 to Na2O ratio of 0.23 is found to have

  8. Geochemistry of sedimentary-derived migmatite from NE Sardinia, Italy

    NASA Astrophysics Data System (ADS)

    Cruciani, Gabriele; Fancello, Dario; Franceschelli, Marcello; Scodina, Massimo

    2015-04-01

    In NE Sardinia at Porto Ottiolu, about 30 km south of Olbia (NE Sardinia), crops out a sequence of migmatized ortho and paragneiss, belonging to the Variscan basement's axial zone. Sedimentary-derived migmatite, which have a layered appearance in the field, were affected by three major variscan folding phase. D2, which is characterized by tight folds, is the most widespread deformation in the field. Leucosomes consists of discontinuous centimetre-thick, coarse-grained layers, that follow the S2 schistosity and are folded by D2 deformation phase. The contact with mesosome is sharp and sometimes marked by melanosome trails. They consist of quartz, plagioclase, very rare K-feldspar, muscovite, biotite, fibrolite, and rare kyanite. Plagioclase is unzoned oligoclase, though in some cases a thin albite rim is observed. Muscovite occurs as: i) single small- to medium-grained flakes enclosed in feldspar; ii) coarse grained crystals associated to biotite, fibrolite, and opaques, iii) in intergrowth with biotite to form thin elongated, slightly oriented trails, marking the faint foliation. Mesosomes are medium-grained, well foliated rocks, consisting of quartz, plagioclase muscovite, , biotite, fibrolite ± K-feldspar ± garnet. Fibrolite, muscovite and biotite are associated, to form strongly oriented, thick levels. Muscovite also occurs as unoriented crystals, showing quartz exsolutions and thin rims. A few mm-thick melanosome is usually present at the boundary between the leucosomes and mesosomes. Leucosomes are characterized by: SiO2: 75.4-77.9; Al2O3: 13.2-14.5; Fe2O3tot: 0.3-0.5; MgO: 0.1-0.2; CaO: 2.7- 3.7; Na2O: 3.9-4.6; K2O: 0.4-0.6 wt.%. An interesting feature is the relative high calcium content already described in other sedimentary-derived migmatite from Sardinia (Cruciani et al., 2008). In the normative Ab-An-Or diagram (Barker, 1979) the leucosomes plot at the boundary between trondhjemite/tonalite fields. All leucosomes are corundum normative and peraluminous. Mesosomes show a lower content of silica and higher content of iron, magnesium and potash. Major elements ranges are: SiO2: 69.9-70.2; Al2O3: 12.8-13.3; Fe2O3tot: 5.4-5.6; MgO: 2.1-2.3; CaO: 2.0-2.1; Na2O: 2.4-2.5; K2O: 2.2-2.4 wt%. Chondrite-normalized REE pattern, shows that all leucosomes are characterized by a positive Eu anomaly and a significant enrichment in LREE. Mesosomes pattern shows a marked negative Eu anomaly, an enrichment in LREE and a depletion in HREE. Total REE content is higher in mesosomes (132-156 ppm) than in leucosomes (51-58 ppm). Trondjhemite/tonalite composition with high CaO, Na2O and low K2O of the leucosomes will be discussed in relation to their significance and origin. References: Barker, F., 1979, Trondhjemite: definition, environment and hypotheses of origin. In: Barker, F. (Ed.), Trondhjemites, dacites, and related rocks. Developments in petrology, vol. 6. Elsevier,Amsterdam, pp. 1-12. Cruciani, G., Franceschelli, M., Elter, F.M., Puxeddu, M., Utzeri, D., 2008, Petrogenesis of Al-silicate-bearing trondhjemitic migmatites from NE Sardinia, Italy. Lithos v. 102, p. 554-574.

  9. Fusing Hyperspectral and LiDAR data from CAO-VSWIR for Increased Data Dimensionality

    NASA Astrophysics Data System (ADS)

    Knapp, D. E.; Asner, G. P.; Boardman, J. W.; Kennedy-Bowdoin, T.; Eastwood, M.; Anderson, C.; Martin, R. E.; Green, R. O.

    2012-12-01

    The use of multi-sensor platforms for scientific data collection requires precise co-location in order to gain maximum data dimensionality for Earth system research. The different types of collection mechanisms of the sensors (e.g., scanning and pushbroom) can make it difficult to precisely match data from multiple sensors, even when the sensors are flown on the same aircraft at the same time. To overcome these problems, the Carnegie Airborne Observatory (CAO) AToMS sensor suite uses a method that maximizes the match between the Light Detection and Ranging (LiDAR), Visible-to-Near Infrared (VNIR), and Visible-to-Shortwave Infrared (VSWIR) sensors. This is done by generating an intensity image from the LiDAR data that serves as a base on which the spectrometers (VNIR and VSWIR) are matched using ground control points (GCPs). To do so, we employ the use of automated tie point matching in the overlap regions of the spectrometers to improve the co-location between flightlines. The combination of the GCPs and tie points produce data that is used to build camera models for the VNIR and VSWIR spectrometers such that they will match the LiDAR data. The result produces a matched hyper-dimensional data set with great scientific information content. We compare the data dimensionality of two contrasting scenes - a built environment at Stanford University and a lowland tropical forest in Amazonia. Principal components analysis revealed 336 dimensions (degrees of freedom) in the Stanford case, and 218 dimensions in the Amazon. The Amazon case presents what could be the highest level of remotely sensed data dimensionality ever reported for a forested ecosystem. Simulated misalignment of data streams reduced the effective information content by up to 48%, highlighting the critical role of achieving high precision when undertaking multi-sensor fusion. The instrumentation and methods described here are a pathfinder for future airborne applications undertaken by the National Ecological Observatory Network (NEON) and other organizations.

  10. On the use of ocean-atmosphere-wave models during an extreme CAO event: the importance of being coupled

    NASA Astrophysics Data System (ADS)

    Carniel, Sandro; Barbariol, Francesco; Benetazzo, Alvise; Bonaldo, Davide; Falcieri, Francesco M.; Miglietta, Mario M.; Ricchi, Antonio; Sclavo, Mauro

    2015-04-01

    During winter 2012 an extreme meteorological event stroke the whole Europe and particularly its central-southern sector. A strong and persistent spit of cold air coming from Siberian region (a Cold Air Outbreak, CAO) insisted on northern Italy and the Adriatic sea basin, leading to decreases in the sea temperatures up to 6 °C in less than two weeks, ice formation on the Venice lagoon and an exceptional snow fall in the Apennine region. In the sea the CAO was associated to a significant episode of dense water formation (DWF), a crucial phenomenon that heavily impacts the whole Adriatic Sea (from the sinking of water masses and associated ventilation of the northernmost shelf, to the flow along the western coast, until the flushing of southern Adriatic open slope and submarine canyons, with associated sediment transport and bottom reshaping). The extent of the DWF event in the Northern Adriatic sub-basin was estimated by means of coastal observatories, ad hoc measurements and, until now, results from existing one-way coupled atmosphere-ocean models. These are characterized by no SST feedback from the ocean to the atmosphere, and therefore by turbulent heat fluxes that may heavily reflect a non-consistent ocean state. The study proposes an investigation of the 2012 CAO using a fully coupled, three components, ocean-atmosphere-wave system (COAWST). Results highlight that, although the energy interplays between air and sea do not seem to significantly impact the wind forecasts, when providing heat fluxes that are consistent with the ocean temperature we find modified heat fluxes and air sea temperatures figures. Moreover, the consistent description of thermal exchanges adopted in the fully coupled model can affect the basin circulation, the quantification of dense water produced mass, and the description of its migration pathways and rates of off-shelf descent.

  11. A study on A-type granites in Suzhou, China

    Microsoft Academic Search

    Zhang Xinglong; Wang Jiabing; Shen Bochun

    1988-01-01

    The Suzhou granite suite is the anorogenic product, which is located on the inactive continental margin of east China. It\\u000a was emplaced about 141 Ma ago, occurring as a stock with a polygonal outline on the surface, belonging to alkali potash-feldspar\\u000a granites with K2O > Na2O, Reit’s alkali coefficient = 0.694, SiO2 = 74.95, and Al2O3\\/(K2O + Na2O)mol= 1. Besides

  12. Nonlinear optical response in alkali-silicate glasses at 800 nm femtosecond irradiations

    Microsoft Academic Search

    Kazem Jamshidi Ghaleh; Nastaran Mansour; David Ashkenasi; Hans-Juergen Hoffmann

    2005-01-01

    Nonlinear optical response of three alkali-silicate glasses by irradiation of a focused 200 femtosecond pulsed laser were investigated using transmittance measurement at 800 nm. The studied glasses are Na2O–CaO–SiO2, K2O–CaO–SiO2 and Cs2O–CaO–SiO2. The nonlinear transmissions are observed for incident pulse energies of above 35 ?J for Cs2O–CaO–SiO2 sample, 60 ?J for Na2O–CaO–SiO2 sample and 70 ?J for K2O–CaO–SiO2 sample. Femtosecond

  13. Interplay of excitonic effects and van Hove singularities in optical spectra: CaO and AlN polymorphs

    Microsoft Academic Search

    A. Riefer; F. Fuchs; C. Rödl; A. Schleife; F. Bechstedt; R. Goldhahn

    2011-01-01

    The quasiparticle band structures and fundamental energy gaps of the rock-salt (rs), zinc-blende (zb), and wurtzite (wz) polymorphs of CaO and AlN are calculated within the G0W0 approximation on top of a self-consistent solution of the generalized Kohn-Sham equation with the hybrid functional HSE03. Based on these reliable electronic structures, the dielectric functions of rs-CaO, zb-AlN, and wz-AlN including excitonic

  14. Steam-Coal Gasification Using CaO and KOH for in Situ Carbon and Sulfur Capture

    SciTech Connect

    Siefert, Nicholas S.; Shekhawat, Dushyant; Litster, Shawn; Berry, David, A

    2013-08-01

    We present experimental results of coal gasification with and without the addition of calcium oxide and potassium hydroxide as dual-functioning catalyst–capture agents. Using two different coal types and temperatures between 700 and 900 °C, we studied the effect of these catalyst–capture agents on (1) the syngas composition, (2) CO{sub 2} and H{sub 2}S capture, and (3) the steam–coal gasification kinetic rate. The syngas composition from the gasifier was roughly 20% methane, 70% hydrogen, and 10% other species when a CaO/C molar ratio of 0.5 was added. We demonstrated significantly enhanced steam–coal gasification kinetic rates when adding small amounts of potassium hydroxide to coal when operating a CaO–CaCO{sub 3} chemical looping gasification reactor. For example, the steam–coal gasification kinetic rate increased 250% when dry mixing calcium oxide at a Ca/C molar ratio of 0.5 with a sub-bituminous coal, and the kinetic rate increased 1000% when aqueously mixing calcium oxide at a Ca/C molar ratio of 0.5 along with potassium hydroxide at a K/C molar ratio of 0.06. In addition, we conducted multi-cycle studies in which CaCO{sub 3} was calcined by heating to 900 °C to regenerate the CaO, which was then reused in repeated CaO–CaCO{sub 3} cycles. The increased steam–coal gasification kinetics rates for both CaO and CaO + KOH persisted even when the material was reused in six cycles of gasification and calcination. The ability of CaO to capture carbon dioxide decreased roughly 2–4% per CaO–CaCO{sub 3} cycle. We also discuss an important application of this combined gasifier–calciner to electricity generation and selling the purge stream as a precalcined feedstock to a cement kiln. In this scenario, the amount of purge stream required is fixed not by the degradation in the capture ability but rather by the requirements at the cement kiln on the amount of CaSO{sub 4} and ash in the precalcined feedstock.

  15. Reconnaissance study of the Taylor Mountains pluton, southwestern Alaska

    USGS Publications Warehouse

    Hudson, Travis L.; Miller, Marti L.; Klimasauskas, Edward P.; Layer, Paul W.

    2010-01-01

    The Taylor Mountains pluton is a Late Cretaceous to early Tertiary (median age 65 + or ? 2 Ma) epizonal, composite biotite granite stock located about 235 km (145 mi) northeast of Dillingham in southwestern Alaska. This 30 km2 (12 mi2) pluton has sharp and discordant contacts with hornfels that developed in Upper Cretaceous clastic sedimentary rocks of the Kuskokwim Group. The three intrusive phases in the Taylor Mountains pluton, in order of emplacement, are (1) porphyritic granite containing large K-feldspar phenocrysts in a coarse-grained groundmass, (2) porphyritic granite containing large K-feldspar and smaller, but still coarse, plagioclase, quartz, and biotite phenocrysts in a fine-grained groundmass, and (3) fine-grained, leucocratic, equigranular granite. The porphyritic granites have different emplacement histories, but similar compositions; averages are 69.43 percent SiO2, 1.62 percent CaO, 5.23 percent FeO+MgO, 3.11 percent Na2O, and 4.50 percent K2O. The fine-grained, equigranular granite is distinctly felsic compared to porphyritic granite; it averages 75.3 percent SiO2, 0.49 percent CaO, 1.52 percent FeO+MgO, 3.31 percent Na2O, and 4.87 percent K2O. Many trace elements including Ni, Cr, Sc, V, Ba, Sr, Zr, Y, Nb, La, Ce, Th, and Nd are strongly depleted in fine-grained equigranular granite. Trace elements are not highly enriched in any of the granites. Known hydrothermal alteration is limited to one tourmaline-quartz replacement zone in porphyritic granite. Mineral deposits in the Taylor Mountains area are primarily placer gold (plus wolframite, cassiterite, and cinnabar); sources for these likely include scattered veins in hornfels peripheral to the Taylor Mountain pluton. The granite magmas that formed the Taylor Mountains pluton are thought to represent melted continental crust that possibly formed in response to high heat flow in the waning stage of Late Cretaceous subduction beneath interior Alaska.

  16. Fault controlled Carboniferous A-type magmatism in the proto-Andean foreland (Sierras Pampeanas, Argentina): Geochemical constraints and petrogenesis

    NASA Astrophysics Data System (ADS)

    Dahlquist, Juan A.; Alasino, Pablo H.; Eby, G. Nelson; Galindo, Carmen; Casquet, César

    2010-03-01

    The intrusion of granitoids into the Eastern Sierras Pampeanas in the Early Carboniferous took place after a long period of mainly compressional deformation that included the Famatinian (Ordovician) and Achalian (Devonian) orogenies. These granitoids occur as small scattered plutons emplaced in a dominant extensional setting, within older metamorphic and igneous rocks, and many of them are arranged along a reactivated large shear zone. A set of 46 samples from different granitic rocks: Huaco granitic complex, San Blas pluton, and the La Chinchilla stock from the Sierra de Velasco, Zapata granitic complex from Sierra de Zapata, and the Los Árboles pluton from Sierra de Fiambalá, display high and restricted SiO 2 contents between 69.2 and 76.4 wt.%. On both FeO/(FeO + MgO) vs. SiO 2 and [(Na 2O + K 2O) - CaO] vs. SiO 2 plots the samples plot in the ferroan and alkaline-calcic to calco-alkaline fields (FeO/(FeO + MgO) = 0.88-1.0%;[(Na 2O + K 2O) - CaO] = 6.3-8.3%), thus showing an A-type granitoid signature. The high concentrations for the High Field Strength Elements (HSFE), such as Y, Nb, Ga, Ta, U, Th, etc. and flat REE patterns showing significant negative Eu anomalies are also typical features of A-type granites. Our petrogenetic model supports progressive fractional crystallization with dominant fractionation of feldspar and a source mineral assemblage enriched in plagioclase. Biotites have distinctive compositions with high FeO/MgO ratios (7.8-61.5), F (360-5610 ppm), and Cl (120-1050 ppm). The FeO/MgO ratios together with the F and Cl content of igneous biotites seem to reflect the nature of their parental host magmas and may be useful in identifying A-type granitoids. The isotopic data (Rb-Sr and Sm-Nd) confirm that the A-type granites represent variable mixtures of asthenospheric mantle and continental crust and different mixtures lead to different subtypes of A-type granite (illustrating the lack of consensus about A-type magma origin). We conclude that prominent shear zones play an important role in providing suitable conduits for ascending asthenospheric material and heat influx in the crust, a hypothesis that is in accord with other recent work on A-type granites.

  17. Solution of MgO, CaO, and TiO[sub 2] in [alpha]-Al[sub 2]O[sub 3

    SciTech Connect

    Grimes, R.W. (Royal Institution of Great Britain, London (United Kingdom). Davy Faraday Research Lab.)

    1994-02-01

    Atomistic simulation methods are used to predict the preferred solution mechanisms and their associated energies. Both full- and partial-charge models are discussed. It was found that defect clustering always results in a significant lowering of the solution energies but does not change the preferred solution reaction of any of the oxides. The large size of the Ca[sup 2+] ion results not only in a higher solution energy (lower solubility) for CaO compared to MgO but also to a different preferred compensation mechanism. The predicted energy for the cosolution of MgO and TiO[sub 2] is dramatically smaller than for either oxide separately. Conversely, whereas solution of TiO[sub 2] aids the solution of CaO, additions of CaO do not support TiO[sub 2] solution.

  18. White luminescence of Dy3+ ions doped 12CaO 7Al2O3 nanopowders under UV light excitation.

    PubMed

    Zhu, Hancheng; Liu, Yuxue; Yan, Duanting; Yan, Xiaolei; Liu, Chunguang; Xu, Changshan

    2011-11-01

    12CaO 7Al2O3:Dy3+ nanopowders were successfully synthesized by the chemical co-precipitation method. X-ray diffraction result shows that the single 12CaO 7Al2O3 phase is formed with Dy3+ ions to replace the Ca2+ ions in the host of 12CaO 7Al2O3. The yellow and blue emissions, attributed to the forced electric dipole transition of 4F(9/2) --> 6H(13/2) centered at 571 nm and the magnetic dipole transition of 4F(9/2) --> 6H(15/2) centered at 480 nm, respectively, were observed. The integrated intensity ratios of yellow to blue increase from 1.63 to 1.70 with Dy3+ concentration increasing from 0.8 to 2.0% for the as-prepared 12CaO 7Al2O3:xDy3+ phosphor. The significantly enhanced emission intensities of 12CaO 7Al2O3:1.0% Dy3+ phosphor annealed at 900 degrees C for 2 hours in vacuum ambient could be ascribed to the decrease of OH(-) groups and the change of the surface topography. The thermal stability and the Commission International de l'Eclairage coordinates were also investigated. All the photoluminescence characteristics indicate that Dy3+ ions doped 12CaO 7Al2O3 may be a good candidate for the solid state lighting phosphor as well as white light-emitting diodes. PMID:22413330

  19. The rates of desulfurization of liquid iron by solid CaO and CaO-saturated liquid iron oxide at 1600‡c

    Microsoft Academic Search

    A. Saelim; D. R. Gaskell

    1983-01-01

    The rates of desulfurization of Fe-O-S melts by CaO crucibles and by CaO-saturated liquid iron oxide have been measured at\\u000a 1600 ‡C. It was found that irons containing 1.62 wt pct and 0.64 wt pct sulfur and 0.070 wt pct oxygen are desulfurized by\\u000a a reaction with the containing CaO crucible which does not involve the formation of a CaS

  20. Charge competition with oxygen molecules determines the growth of gold particles on doped CaO films.

    PubMed

    Cui, Yi; Huang, Kai; Nilius, Niklas; Freund, Hans-Joachim

    2013-01-01

    The influence of gas-phase oxygen on the growth of Au nanoparticles on Mo-doped CaO films has been investigated by means of low temperature scanning tunnelling microscopy and X-ray photoelectron spectroscopy. Whereas at ideal vacuum conditions, only 2D Au islands develop on the oxide surface, the fraction of 3D deposits increases with increasing O2 pressure until they become the dominant species in 106 mbar oxygen. The morphology crossover arises from changes in the interfacial electron flow between Mo donors in the CaO lattice and different ad-species on the oxide surface. In the absence of 02 molecules, the donor electrons are predominately transferred to the Au ad-atoms, which consequently experience enhanced binding to the oxide surface and agglomerate into 2D islands. In an oxygen atmosphere, on the other hand, a substantial fraction of the excess electrons is trapped by adsorbed O2 molecules, while the Au atoms remain neutral and assemble into tall 3D particles that are typical for non-doped oxides. Our experiments demonstrate how the competition for charge between different adsorbates governs the physical and chemical properties of doped oxides, so widely used in heterogeneous catalysis. PMID:24015581

  1. Thermal conductivity and Seebeck coefficient of 12CaO?7Al2O3 electride with a cage structure

    NASA Astrophysics Data System (ADS)

    Kim, Sung Wng; Tarumi, Ryuichi; Iwasaki, Hideo; Ohta, Hiromichi; Hirano, Masahiro; Hosono, Hideo

    2009-08-01

    Thermal conductivity (?) and Seebeck coefficient (?) of electron-doped light-metal oxide 12CaO?7Al2O3 (C12A7 electride) with a subnanometer-sized cage structure are reported on single crystals with various electron concentrations (Ne) . The semiconducting C12A7 electride exhibits n -type conduction with the highest ? value of -100?VK-1 at 300 K. The ? exhibits an amorphouslike T2 dependence at low temperatures and varies between 2.3 and 4.5Wm-1K-1 at 300 K. This is an order-of-magnitude lower than that of the constituents, CaO (15Wm-1K-1) and Al2O3 (30Wm-1K-1) . These properties are attributed to the cage structure, suggesting that the semiconducting electride should be regarded as a phonon glass and electron crystal material. The thermoelectric performance of electrides evaluated by a dimensionless figure of merit (ZT) shows an optimized value of 2×10-3 at 300 K for the semiconducting electride with Ne of 5×1020cm-3 .

  2. Evolution of the electronic structure of CaO thin films following Mo interdiffusion at high temperature

    NASA Astrophysics Data System (ADS)

    Cui, Yi; Pan, Yi; Pascua, Leandro; Qiu, Hengshan; Stiehler, Christian; Kuhlenbeck, Helmut; Nilius, Niklas; Freund, Hans-Joachim

    2015-01-01

    The electronic structure of CaO films of 10-60 monolayer thickness grown on Mo(001) has been investigated with synchrotron-mediated x-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). Upon annealing or reducing the thickness of the film, a rigid shift of the CaO bands to lower energy is revealed. This evolution is explained with a temperature-induced diffusion of Mo ions from the metal substrate to the oxide and their accumulation in the interface region of the film. The Mo substitutes divalent Ca species in the rocksalt lattice and is able to release electrons to the system. The subsequent changes in the Mo oxidation state have been followed with high-resolution XPS measurements. While near-interface Mo transfers extra electrons back to the substrate, generating an interface dipole that gives rise to the observed band shift, near-surface species are able to exchange electrons with adsorbates bound to the oxide surface. For example, exposure of O2 results in the formation of superoxo species on the oxide surface, as revealed from STM measurements. Mo interdiffusion is therefore responsible for the pronounced donor character of the initially inert oxide, and largely modifies its adsorption and reactivity behavior.

  3. Petrological and experimental phase equilibria constraints on magma storage conditions beneath Cerro Uturuncu, Bolivia

    NASA Astrophysics Data System (ADS)

    Muir, D. D.; Blundy, J. D.; Rust, A.; Brooker, R.

    2011-12-01

    Volcanic unrest manifest as surface deformation detected with InSAR recently drew attention to Cerro Uturuncu, a dormant dacitic stratovolcano in the Bolivian altiplano that last erupted 271 ka. Magma intrusion in the mid to upper crust is thought to be responsible for the deformation calculated as 1-2 cm/yr central uplift rate between 1992 and 2006. Using petrological and experimental phase equilibrium experiments designed to replicate natural mineral assemblages, phase proportions and phase compositions, we aim to constrain the pre-eruptive pressure, temperature, fO2 and fH2O storage conditions of Uturuncu magmas. Plagioclase, orthopyroxene, biotite, titaniferous magnetite, ilmenite, apatite and a rhyolitic glassy matrix are ubiquitous in all 50 thin sections of Uturuncu lava samples studied. All of the lavas are porphyritic with examples of normal and reverse zoning in plagioclase and orthopyroxene phenocrysts. Biotite commonly has dehydration reaction rims. Magmatic temperatures of ~870°C and fO2s around NNO+1.3 have been estimated from coexisting Fe-Ti oxides. A water content of 3.6 wt%, similar to those calculated in melt inclusions using the by-difference method, was estimated using plagioclase-melt equilibria and, assuming the magma was water saturated, VolatileCalc indicates a magma storage pressure of at least 91 MPa. Several previous studies have experimentally investigated phase equilibria of silicic magmatic systems including Volcan San Pedro (Chile), Mount Unzen (Japan), and Fish Canyon and Mount St. Helens (USA). Compared to these systems, Uturuncu lavas have higher SiO2 by 1.0-4.2 wt%; higher K2O by 0.5-3.3 wt%; and Na2O lower by 1.9-2.8 wt%, and are unique in crystallising biotite in the absence of hornblende. Crystallisation experiments are being performed in cold-seal hydrothermal pressure apparatuses with two synthetic starting materials that replicate the bulk dacite and rhyolite glass chemistry of a glassy lava sample with a relatively low microlite content and a total crystallinity of 36 vol%. The dacite composition is SiO2 67.0 wt%, Al2O3 15.9 wt%, K2O 4.5 wt%, FeO 4.0 wt%, CaO 3.6 wt%, Na2O 2.1 wt%, MgO 1.5 wt%; the rhyolitic composition is SiO2 75.1 wt%, Al2O3 13.4 wt%, K2O 6.7 wt%, FeO 1.1 wt%, CaO 0.8 wt%, Na2O 2.2 wt%, MgO 0.2 wt%. Experiments are being conducted at temperatures between 800-900°C and pressures between 50-300 MPa at water saturated conditions. The results will be compared to natural samples to assess storage conditions of the 890-271 ka eruptions at Uturuncu, and the storage depths inferred today from geophysical data.

  4. Comparison of the safety of drug delivery via HFA- and CFC-metered dose inhalers in CAO.

    PubMed

    Huchon, G; Hofbauer, P; Cannizzaro, G; Iacono, P; Wald, F

    2000-04-01

    The objective of this study was to compare the long-term safety of a fixed combination of fenoterol hydrobromide (50 microg) and ipratropium bromide (20 microg) delivered using a metered dose inhaler (MDI) formulated with a non-chlorinated propellant, hydrofluoroalkanel34a (HFA-MDI), with delivery using the conventional chlorofluorocarbon propellant (CFC-MDI, Berodual/Bronchodual). The study was designed according to Safety Assessment of Marketed Medicines (SAMM) guidelines, to reflect as far as possible the use of MDls under normal prescribing conditions. Two thousand and twenty-seven patients with chronic airways obstruction (CAO) were enrolled from 99 centres in France, 95 centres in Germany and 24 centres in Italy. Following a 2-week run-in period, patients were randomized on a 2:1 basis (1,348 patients to HFA-MDI, 679 patients to CFC-MDI) to receive a flexible dose regimen of the combination (2 puffs, 2-4 times a day, as prescribed by the investigator) during a 12-week open label phase. The overall incidence of adverse events was comparable between both groups. In addition, the incidence of respiratory side effects was also similar, with CAO exacerbations or bronchitis the most frequently recorded events. The safety profile of the HFA formulation was comparable to those of the marketed CFC-MDIs used in Germany and France/Italy. No clinically significant differences were detected between HFA134a or CFC driven inhalers on the switch from CFC- to HFA-MDI (2 weeks before randomisation versus 2 weeks after randomization). There was a trend for taste complaints to be reported more frequently by patients in the HFA-MDI group (0.7% before randomization versus 3.4% after randomization). This, however, was an expected finding as the HFA134a formulation does have a different taste to the CFC formulation. No difference between formulations was observed in the incidences of coughing or paradoxical bronchospasm. The incidence of falls in FEV1 >15% within 15 min following inhalation at each of the clinic visits was 1.2% for both CFC- and HFA-MDIs. In conclusion, administration of a fenoterol/ipratropium bromide combination via hydrofluoroalkane-metered dose inhaler is as safe as delivery by the currently available chlorofluorocarbon-metered dose inhaler, in an extended population of patients with CAO under normal prescribing conditions. PMID:10780756

  5. Genomic Variants of ATF3 in Patients With Hypospadias Nicolas Kalfa, Benchun Liu, Ophir Klein, Ming-Hsieh Wang, Mei Cao and Laurence S. Baskin*

    E-print Network

    Klein, Ophir

    Genomic Variants of ATF3 in Patients With Hypospadias Nicolas Kalfa, Benchun Liu, Ophir Klein, Ming-Hsieh Wang, Mei Cao and Laurence S. Baskin* From the Center for the Study and Treatment of Hypospadias expressed during genital development, could be implicated in the etiology of hypospadias. ATF3 is up

  6. A picosecond electron gun for surface analysis M. Aeschlimann,a) E. Hull, J. Cao,b) C. A. Schmuttenmaer, L. G. Jahn,@ Y. Gao,b)

    E-print Network

    Cao, Jianming

    A picosecond electron gun for surface analysis M. Aeschlimann,a) E. Hull, J. Cao,b) C. A investigations for a new design of an ultrashort pulsed laser activated electron gun for time resolved surface gun, in spite of an unusually long focal length and a small convergence angle of the pulsed electron

  7. 1930 IEEE TRANSACTIONS ON AUTOMATIC CONTROL, VOL. 46, NO. 12, DECEMBER 2001 [24] Y. Y. Cao, J. Lames, and Y. X. Sun, "Static output feedback stabilization

    E-print Network

    Fridman, Emilia

    1930 IEEE TRANSACTIONS ON AUTOMATIC CONTROL, VOL. 46, NO. 12, DECEMBER 2001 [24] Y. Y. Cao, J a linearized model with distributed delay for the feeding system and the combustion chamber in a liquid mono- propellant rocket motor with pressure feeding. In this model a non- steady flow was assumed and nonuniform

  8. FOURIER TRANSFORM INFRARED PHOTOACOUSTIC SPECTROSCOPY CHARACTERIZATION OF SULFUR-OXYGEN SPECIES RESULTING FROM THE REACTION OF SO2 WITH CAO AND CACO3

    EPA Science Inventory

    Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) has been used to investigate the reaction of SO2 in He with CaO and CaCO3 particles at temperatures between 25 and 900 C. SO2 reacts with CaC at 25 C, while the reaction of Ca-CO3 with SO2 is first evident at 550 C ...

  9. DETERMINATION DE LA POSITION DES ATOMES D'HYDROGNE DANS L'HYDROGRINAT Al2O3, 3CaO, 6H2O

    E-print Network

    Paris-Sud XI, Université de

    100 °C. Un spectre de résonance magnétique nucléaire a été enregistré sur l'aluminate en poudre ; le of water at 100 °C. A nuclear magnetic résonance spectrum of the powdered aluminate was recorded cristallographique d 3~ 0, ~). Dans l'aluminate 3CaO, ce site ne comporte pas d'atomes. Les quatre atomes d

  10. LUSTER: Wireless Sensor Network for Environmental Research L. Selavo, A. Wood, Q. Cao, T. Sookoor, H. Liu, A. Srinivasan, Y. Wu, W. Kang,

    E-print Network

    Stankovic, John A.

    LUSTER: Wireless Sensor Network for Environmental Research L. Selavo, A. Wood, Q. Cao, T. Sookoor, H. Liu, A. Srinivasan, Y. Wu, W. Kang, J. Stankovic, D. Young, J. Porter Department of Computer Commonwealth University University of Virginia {selavo|wood|qc9b|sookoor|hl4d|av3b|yw5s|wk5f

  11. Highly unidirectional InAs/InGaAs/GaAs quantum-dot ring lasers Hongjun Cao, Hui Deng, Hai Ling, Chiyu Liu, Vladimir A. Smagley,

    E-print Network

    New Mexico, University of

    Highly unidirectional InAs/InGaAs/GaAs quantum-dot ring lasers Hongjun Cao, Hui Deng, Hai Ling 2005 We report fabrication and characterization of semiconductor ring lasers with quantum-dot active region. The InAs/InGaAs/GaAs "dots-in-a-well" ridge-waveguide ring lasers are monolithically integrated

  12. Online Testing Framework for Web Services Composition Tien-Dung Cao1, Patrick Felix1, Richard Castanet1 and Ismail Berrada2

    E-print Network

    Paris-Sud XI, Université de

    Online Testing Framework for Web Services Composition Tien-Dung Cao1, Patrick F´elix1, Richard Rochelle, France. Email: ismail.berrada@univ-lr.fr Abstract--Testing conceptually consists of three activities: test case generation, test case execution and verdict assignment. Using online testing, test

  13. Testing Web Services Composition using the TGSE Tool Tien-Dung Cao1, Patrick Felix1, Richard Castanet1 and Ismail Berrada2

    E-print Network

    Testing Web Services Composition using the TGSE Tool Tien-Dung Cao1, Patrick F´elix1, Richard Rochelle, France. Email: ismail.berrada@univ-lr.fr Abstract This paper proposes an approach to test (actively and passively) Web services composition described in BPEL using TGSE (Test Generation, Simulation

  14. A Progress Report on Flexible Neurotransmitters Sensors H. Cao, C. M. Nguyen, A-L. Li, Y. Peng, and J-C. Chiao

    E-print Network

    Chiao, Jung-Chih

    A Progress Report on Flexible Neurotransmitters Sensors H. Cao, C. M. Nguyen, A-L. Li, Y. Peng, and J-C. Chiao Introduction: L-glutamate, which is the most abundant excitatory neurotransmitter in vivo. In this work, the progress on our implantable probes for sensing neurotransmitters and recording

  15. Growth of Thin InAlP Native Oxides for GaAs Metal-Oxide-Semiconductor Devices Mr. Ying Cao1

    E-print Network

    Growth of Thin InAlP Native Oxides for GaAs Metal-Oxide-Semiconductor Devices Mr. Ying Cao1 ; Ms thermal native oxides towards thicknesses suitable for use in GaAs metal-oxide-semiconductor (MOS) devices, we observed that thin 7 nm oxide films showed Schottky-diode-like behavior with relatively large

  16. Copyrighted (Textbook) Fei Hu and Xiaojun Cao, Wireless Sensor Networks: Principles and Practice, CRC Press Page 1 Chapter 2: Hardware Sensor Mote

    E-print Network

    Hu, Fei

    , CRC Press Page 1 Chapter 2: Hardware Sensor Mote Architecture and Design In this chapter, we;Copyrighted (Textbook) Fei Hu and Xiaojun Cao, Wireless Sensor Networks: Principles and Practice, CRC Press, CRC Press Page 3 Signal Processing) chips. After receiving those raw analog data, a CPU must

  17. Analysis of the kinetic slowing down during carbonation of CaO by CO2 Lydie Rouchon, Loc Favergeon, Michle Pijolat

    E-print Network

    Paris-Sud XI, Université de

    ,5], chemical heat pump [6-9], energy's storage [10-11], reaction integrated gasification process for H2 cause of climate change [1]. So, decrease of CO2 emitted by large industrial combustion sources or power at an industrial scale [3]. CaO (s) + CO2 (g) CaCO3 (s) (R1) This carbonation reaction has been studied from

  18. L. Cao, H. Sihler, U. Platt and E. Gutheil: Chemical mechanisms for ozone depletion and halogen release: Supplement 1 1 Chemical reaction mechanisms

    E-print Network

    Meskhidze, Nicholas

    release: Supplement 1 1 Chemical reaction mechanisms: Mechanism for bromine containing species: Reaction kL. Cao, H. Sihler, U. Platt and E. Gutheil: Chemical mechanisms for ozone depletion and halogen [(molec. cm-3 )1-n s-1 ] Reaction order n Reference Reaction No. O3 +h O(1 D)+O2 4.70 10-7 1 Lehrer et al

  19. Chlorophyll antenna size adjustments by irradiance in Dunaliella salina involve coordinate regulation of chlorophyll a oxygenase ( CAO ) and Lhcb gene expression

    Microsoft Academic Search

    Tatsuru Masuda; Ayumi Tanaka; Anastasios Melis

    2003-01-01

    To elucidate the mechanism of irradiance-dependent adjustments in the chlorophyll antenna size of photosynthesis, we addressed the regulation of expression of genes encoding a variety of chlorophyll biosynthesis enzymes and that of the Lhcb genes in the model organism Dunaliella salina. Among the chlorophyll biosynthesis enzymes tested, only the chlorophyll a oxygenase (CAO) gene responded to changes in the level

  20. NUMERICAL SIMULATIONS OF AIR FLOW AND HEAT TRANSFER VIA PDES Fei Cao, Luz Angelica Caudillo-Mata, Natalia Iwanski, Yong Li, Kamran Sadiq,

    E-print Network

    NUMERICAL SIMULATIONS OF AIR FLOW AND HEAT TRANSFER VIA PDES By Fei Cao, Luz Angelica Caudillo://www.ima.umn.edu #12;IMA Mathematical Modeling in Industry XVII Workshop: Numerical Simulations of Air Flow and Heat of a simplified PDE model for simulating air flow and heat transfer, with the aim of gaining experience

  1. Periodic Hartree-Fock study of B1 ? B2 reactions: phase transition in CaO

    NASA Astrophysics Data System (ADS)

    D'Arco, Philippe; Jolly, Luc-Henri; Silvi, Bernard

    1992-08-01

    The periodic Hartree-Fock method has been used to sample the potential energy hypersurface of CaO to determine a collective reaction pathway between the low-pressure (NaCl) and high-pressure (CsCl) phases. The predicted transition pressure, 68 GPa, is in good agreement with both experimental data and previous theoretical studies. At low pressure the enthalpy ( E + PV) surface presents only one minimum corresponding to the B1 (NaCl) structure. A second minimum appears at the B2 (CsCl) geometry when the pressure is increased. The transformation kinetics is estimated using the Johnson-Mehl model coupled to random nucleation and interface-controlled growth. Independently of the interfacial energy, the kinetics is highly pressure dependent. A pressure hysteresis loop is predicted. The results presented are in qualitative agreement with available data.

  2. X-ray fluorescence analysis with micro glass beads using milligram-scale siliceous samples for archeology and geochemistry

    NASA Astrophysics Data System (ADS)

    Ichikawa, Shintaro; Nakamura, Toshihiro

    2014-06-01

    A micro glass bead technique was developed to assay precious siliceous samples for geochemical and archeological analyses. The micro-sized (approximately 3.5 mm in diameter and 0.8 mm in height) glass beads were prepared by mixing and fusing 1.1 mg of the powdered sample and 11.0 mg of the alkali lithium tetraborate flux for wavelength-dispersive X-ray fluorescence determination of major oxides (Na2O, MgO, Al2O3, SiO2, P2O5, K2O, CaO, TiO2, MnO, and total Fe2O3). The preparation parameters, including temperature and agitation during the fusing process, were optimized for the use of a commercial platinum crucible rather than a custom-made crucible. The procedure allows preparation of minute sample amounts of siliceous samples using conventional fusing equipment. Synthetic calibration standards were prepared by compounding chemical reagents such as oxides, carbonates, and diphosphates. Calibration curves showed good linearity with r values > 0.997, and the lower limits of detection were in the 10s to 100s of ?g g- 1 range (e.g., 140 ?g g- 1 for Na2O, 31 ?g g- 1 for Al2O3, and 8.9 ?g g- 1 for MnO). Using the present method, we determined ten major oxides in igneous rocks, stream sediments, ancient potteries, and obsidian. This was applicable to siliceous samples with various compositions, because of the excellent agreement between the analytical and recommended values of six geochemical references. This minimal-scale analysis may be available for precious and limited siliceous samples (e.g., rock, sand, soil, sediment, clay, and archeological ceramics) in many fields such as archeology and geochemistry.

  3. Production of smoke particles condensed from K+N2O or Zn+O2 vapor

    NASA Astrophysics Data System (ADS)

    Hecht, J.; Norton, M. A.

    1981-04-01

    K and Zn metal were evaporated in an inert gas and oxidant atmosphere at pressures of 1-50 Torr. The resultant smoke was analyzed as to size and composition by light scattering and electron microscopy techniques. The formation of K2O and ZnO particles was consistent with previous work on Na2O particle formation.

  4. A Structurally Based Viscosity Model for Oxide Melts

    NASA Astrophysics Data System (ADS)

    Zhang, Guo-Hua; Chou, Kuo-Chih; Mills, Ken

    2014-04-01

    A structurally based viscosity model is proposed to represent the viscosity of oxide melts as functions of both temperature and composition; The oxide melts cover the following constituents: Li2O, Na2O, K2O, MgO, CaO, SrO, BaO, FeO, MnO, Al2O3, SiO2, CaF2, TiO2, Fe2O3, and P2O5. The model describes the slag structure in terms of the various forms of oxygen ions which are classified according to the metal cations they bond with. Approximate methods for calculating the concentrations of these oxygen ions are proposed and are then used to describe the effect of melt structure on viscosity. The model provides a good description of the variations in viscosity with composition and temperature. The measured viscosities were compared with values calculated with the model, and the current model was found to provide reliable estimates of viscosities of slags used in various industrial processes ( e.g., blast furnace, basic oxygen steelmaking, ladle refining, continuous casting of steel, coal gasification, and electroslag remelting).

  5. Liquidus Temperature of High-Level Waste Borosilicate Glasses with Spinel Primary Phase

    SciTech Connect

    Hrma, Pavel R. (BATTELLE (PACIFIC NW LAB)); Vienna, John D. (BATTELLE (PACIFIC NW LAB)); Crum, Jarrod V. (BATTELLE (PACIFIC NW LAB)); Piepel, Gregory F. (BATTELLE (PACIFIC NW LAB)); Mika, Martin (ASSOC WESTERN UNIVERSITY); Robert W. Smith; David W. Shoesmith

    2000-01-01

    Liquidus temperatures (TL) were measured for high-level waste (HLW) borosilicate glasses covering a Savannah River composition region. The primary crystallization phase for most glasses was spinel, a solid solution of trevorite (NiFe2O4) with other oxides (FeO, MnO, and Cr2O3). The TL values ranged from 859 to 1310?C. Component additions increased the TL (per mass%) as Cr2O3 261?C, NiO 85?C, TiO2 42?C, MgO 33?C, Al2O3 18?C, and Fe2O3 18?C and decreased the TL (per mass%) as Na2O -29?C, Li2O -28?C, K2O -20?C, and B2O3 -8?C. Other oxides (CaO, MnO, SiO2, and U3O8) had little effect. The effect of RuO2 is not clear.

  6. Fluorescence properties of Eu3+-doped alumino silicate glasses

    NASA Astrophysics Data System (ADS)

    Herrmann, Andreas; Kuhn, Stefan; Tiegel, Mirko; Rüssel, Christian

    2014-11-01

    Alumino silicate glasses of a very broad range of molar compositions doped with 1 ? 1020 Eu3+ cm-3 (about 0.2 mol% Eu2O3) were prepared. As network modifier oxides Li2O, Na2O, K2O, MgO, CaO, SrO, BaO, ZnO, PbO, Y2O3 and La2O3 have been used. All glasses show relatively broad fluorescence excitation and emission spectra. For most glasses only a weak effect of the glass composition on the excitation and emission spectra is observed. Although the glasses should be structurally similar, notable differences are found for the fluorescence lifetimes. These increase steadily with decreasing mean atomic weight, decreasing refractive index and decreasing optical basicity of the glasses, which may be explained by local field effects. An exception from this rule are the strontium, barium and potassium containing glasses, which show significantly increased fluorescence lifetimes despite of their high refractive index, optical basicity and molecular weight. The non mono-exponential fluorescence decay curves as well as the fluorescence spectra indicate a massive change in the local surroundings of the doped rare earth ions for these glasses.

  7. Straczekite, a new calcium barium potassium vanadate mineral from Wilson Springs, Arkansas.

    USGS Publications Warehouse

    Evans, H.T., Jr.; Nord, G.; Marinenko, J.; Milton, C.

    1984-01-01

    Straczekite occurs as a rare secondary mineral in fibrous seams, along with other V minerals (A.M. 64-713), in ore from the vanadium mine in Wilson Springs (formerly Potash Sulfur Springs), Garland County, Arkansas. It forms soft, thin laths of dark greenish black crystals up to 0.5 mm in length. Indexed XRD data are tabulated; strongest lines 3.486(100), 10.449(50), 1.8306(50), 1.9437(15) A; a 11.679, b 3.6608, c 10.636 A, beta 100.53o; space group C2/m, C2 or Cm. Chemical analysis gave V2O5 66.4, V2O4 15.3, Fe2O3 0.9, Na2O 0.4, K2O 1.8, CaO 2.5, BaO 5.5, H2O 7.2, = 100.0, leading to the formula (Ca0.39Ba0.31K0.33Na0.11)- 196(V4+1.59V5+6.31Fe3+0.10)O20.02(H2O)2.9; Dcalc. 3.21 g/cm3. A possible layer structure is discussed. The name is for J. A. Straczek, Chief Geologist at Union Carbide Corp.-R.A.H.

  8. High-Temperature Viscosity Of Commercial Glasses

    SciTech Connect

    Hrma, Pavel R.; See, Clem A.; Lam, Oanh P.; Minister, Kevin B.

    2005-01-01

    Viscosity was measured for six types of commercial glasses: low-expansion-borosilicate glasses, E glasses, fiberglass wool glasses, TV panel glasses, container glasses, and float glasses. Viscosity data were obtained with rotating spindle viscometers within the temperature range between 900°C and 1550°C; the viscosity varied from 1 Pa?s to 750 Pa?s. Arrhenius coefficients were calculated for individual glasses and linear models were applied to relate them to the mass fractions of 11 major components (SiO2, CaO, Na2O, Al2O3, B2O3, BaO, SrO, K2O, MgO, PbO, and ZrO2) and 12 minor components (Fe2O3, ZnO, Li2O, TiO2, CeO2, F, Sb2O3, Cr2O3, As2O3, MnO2, SO3, and Co3O4). The models are recommended for glasses containing 42 to 84 mass% SiO2 to estimate viscosities or temperatures at a constant viscosity for melts within both the temperature range from 1100°C to 1550°C and viscosity range from 10 to 400 Pa?s.

  9. Environmental changes in the western Amazônia: morphological framework, geochemistry, palynology and radiocarbon dating data.

    PubMed

    Horbe, Adriana M C; Behling, Hermann; Nogueira, Afonso C R; Mapes, Russell

    2011-09-01

    The sediments from the Coari lake, a "terra firme" lake sculpted into Plio-Pleistocene deposits, and the Acará lake, a flooding-type lake developed on Quaternary sediments in the floodplain of the mid-Solimões river, in the western Amazônia, Brazil, were studied to investigate the environmental condition of their developing. This study includes mineral composition, geochemistry, Pb isotope, palinology, radiocarbon-age and morphological framework of the lakes obtained from SRTM satellite images. The geological and the environmental conditions in the two lakes are highly variable and suggest that their evolution reflect autogenic processes under humid rainforest condition. Although kaolinite, quartz, muscovite, illite, and smectite are the main minerals in both lakes, the geochemistry indicates distinct source, the Acará lake sediments have higher concentrations of Al(2)O(3), Fe(2)O(3), FeO, CaO, K(2)O, MgO, Na(2)O, P(2)O(5), Ba, V, Cu, Ni, Zn, Pb, Sr, Li, Y and La and have more radiogenic Pb than the Coari lake sediments. The radiocarbon ages suggest that at 10160 yr BP the Coari lake started to be developed due to avulsion of the Solimões river, and the Acará lake was formed by the meander abandonment of Solimões river retaining its grass dominated shore at ca. 3710 yr BP. PMID:21830005

  10. Calculation of Oxygen Fugacity in High Pressure Metal-Silicate Experiments and Comparison to Standard Approaches

    NASA Technical Reports Server (NTRS)

    Righter, K.; Ghiorso, M.

    2009-01-01

    Calculation of oxygen fugacity in high pressure and temperature experiments in metal-silicate systems is usually approximated by the ratio of Fe in the metal and FeO in the silicate melt: (Delta)IW=2*log(X(sub Fe)/X(sub FeO)), where IW is the iron-wustite reference oxygen buffer. Although this is a quick and easy calculation to make, it has been applied to a huge variety of metallic (Fe- Ni-S-C-O-Si systems) and silicate liquids (SiO2, Al2O3, TiO2, FeO, MgO, CaO, Na2O, K2O systems). This approach has surely led to values that have little meaning, yet are applied with great confidence, for example, to a terrestrial mantle at "IW-2". Although fO2 can be circumvented in some cases by consideration of Fe-M distribution coefficient, these do not eliminate the effects of alloy or silicate liquid compositional variation, or the specific chemical effects of S in the silicate liquid, for example. In order to address the issue of what the actual value of fO2 is in any given experiment, we have calculated fO2 from the equilibria 2Fe (metal) + SiO2 (liq) + O2 = Fe2SiO4 (liq).

  11. Characterization of zinc-releasing three-dimensional bioactive glass scaffolds and their effect on human adipose stem cell proliferation and osteogenic differentiation.

    PubMed

    Haimi, Suvi; Gorianc, Giada; Moimas, Loredana; Lindroos, Bettina; Huhtala, Heini; Räty, Sari; Kuokkanen, Hannu; Sándor, George K; Schmid, Chiara; Miettinen, Susanna; Suuronen, Riitta

    2009-10-01

    While the addition of zinc ions to bioactive ceramics has been shown to enhance the proliferation and osteogenic differentiation of osteoblast-like cells, contradictory results have been found. Therefore, the effect of zinc-releasing ceramics on cell proliferation and differentiation into osteogenic lineages requires further clarification. The aim of this study was to evaluate the effects of zinc addition on the degradation profile of three-dimensional bioactive glass scaffold, and on the proliferation and osteogenesis of human adipose stem cells (hASCs) in these scaffolds. Bioactive glass scaffolds containing Na(2)O, K(2)O, MgO, CaO, B(2)O(3), TiO(2), P(2)O(5) and SiO(2) were prepared. The degradation was evaluated by weight loss measurement, scanning electron microscopy and elemental analysis. The degradation profile of bioactive glass was shown to slow down with the addition of zinc. Qualitative live/dead staining showed that zinc addition to bioactive glass inhibits cell spreading and proliferation of hASCs. However, zinc addition had no significant effect on DNA content, alkaline phosphatase activity and osteopontin concentration of hASCs when measured quantitatively. Our results suggest that the possible stimulatory effect of addition of zinc on hASC proliferation and osteogenesis was not detected because addition of zinc slowed down the degradation rate of the studied bioactive glass scaffolds. PMID:19428318

  12. Reactions of yttria-stabilized zirconia with oxides and sulfates of various elements

    NASA Technical Reports Server (NTRS)

    Zaplatynsky, I.

    1978-01-01

    The reactions between partially stabilized zirconia, containing 8 weight-percent yttria, and oxides and sulfates of various elements were studied at 1200, 1300, and 1400 C for times to 800, 400, and 200 hours, respectively. These oxides and sulfates represent impurities and additives potentially present in gas turbine fuels or impurities in the turbine combustion air as well as the elements of the substrate alloys in contact with zirconia. Based on the results, these compounds can be classified in four groups: (1) compounds which did not react with zirconia (Na2SO4, K2SO4, Cr2O3, Al2O3 and NiO); (2) compounds that reached completely with both zirconia phases (CaO, BaO, and BaSO4); (3) compounds that reacted preferentially with monoclinic zirconia (Na2O, K2O, CoO, Fe2O3, MgO, SiO2, and ZnO); and (4) compounds that reacted preferentially with cubic zirconia (V2O5, P2O5).

  13. Principal Component Analysis of Chinese Porcelains from the Five Dynasties to the Qing Dynasty

    NASA Astrophysics Data System (ADS)

    Yap, C. T.; Hua, Younan

    1992-10-01

    This is a study of the possibility of identifying antique Chinese porcelains according to the period or dynasty, using major and minor chemical components (SiO2 , Al2O3 , Fe2O3 , K2O, Na2O, CaO and MgO) from the body of the porcelain. Principal component analysis is applied to published data on 66 pieces of Chinese procelains made in Jingdezhen during the Five Dynasties and the Song, Yuan, Ming and Qing Dynasties. It is shown that porcelains made during the Five Dynasties and the Yuan (or Ming) and Qing Dynasties can be segregated completely without any overlap. However, there is appreciable overlap between the Five Dynasties and the Song Dynasty, some overlap between the Song and Ming Dynasties and also between the Yuan and Ming Dynasties. Interestingly, Qing procelains are well separated from all the others. The percentage of silica in the porcelain body decreases and that of alumina increases with recentness with the exception of the Yuan and Ming Dynasties, where this trend is reversed.

  14. The Oro Grande, New Mexico, chondrite and its lithic inclusion.

    NASA Technical Reports Server (NTRS)

    Fodor, R. V.; Keil, K.; Jarosewich, E.

    1972-01-01

    The Oro Grande, New Mexico, U.S.A., chondrite was found in 1971. Electron microprobe analyses and microscopic examination show the following mineralogy: olivine (Fa 19.3 mole %), orthopyroxene (Fs 16.2 mole %), diopside, feldspar (An 13.6 mole %), chlorapatite, whitlockite, kamacite, taenite, troilite, chromite, and an iron-bearing terrestrial weathering product. A bulk chemical analysis of the meteorite shows the following results (weight %): Fe 0.84, Ni 1.46, Co 0.07, FeS 3.62, SiO2 34.18, TiO2 0.14, Al2O3 1.83, Cr2O3 0.55, Fe2O3 21.25, FeO 9.13, MnO 0.31, MgO 21.52, CaO 1.72, Na2O 0.70, K2O 0.08, P2O5 0.25, H2O(+) 2.14, H2O(-) 0.40, C 0.22, sum 100.41. On the basis of composition and texture the Oro Grande meteorite is classified as an H5 chondrite.

  15. Novel systems for tailored neurotrophic factor release based on hydrogel and resorbable glass hollow fibers.

    PubMed

    Novajra, G; Tonda-Turo, C; Vitale-Brovarone, C; Ciardelli, G; Geuna, S; Raimondo, S

    2014-03-01

    A novel system for the release of neurotrophic factor into a nerve guidance channel (NGC) based on resorbable phosphate glass hollow fibers (50P2O5-30CaO-9Na2O-3SiO2-3MgO-2.5K2O-2.5TiO2 mol%) in combination with a genipin-crosslinked agar/gelatin hydrogel (A/G_GP) is proposed. No negative effect on the growth of neonatal olfactory bulb ensheathing cell line (NOBEC) as well as on the expression of pro- and anti-apoptotic proteins was measured in vitro in the presence of fiber dissolution products in the culture medium. For the release studies, fluorescein isothiocyanate-dextran (FD-20), taken as growth factor model molecule, was solubilized in different media and introduced into the fiber lumen exploiting the capillary action. The fibers were filled with i) FD-20/phosphate buffered saline (PBS) solution, ii) FD-20/hydrogel solution before gelation and iii) hydrogel before gelation, subsequently lyophilized and then filled with the FD-20/PBS solution. The different strategies used for the loading of the FD-20 into the fibers resulted in different release kinetics. A slower release was observed with the use of A/G_GP hydrogel. At last, poly(?-caprolactone) (PCL) nerve guides containing the hollow fibers and the hydrogel have been fabricated. PMID:24433883

  16. The lunar regolith - Chemistry, mineralogy, and petrology

    NASA Technical Reports Server (NTRS)

    Papike, J. J.; Simon, S. B.; Laul, J. C.

    1982-01-01

    The data base on the lunar regolith is surveyed to form a synthesis of the lunar regolith chemistry, mineralogy, and petrology. The data were derived from samples collected by the Apollo missions 11-17 and the Luna 16, 20, and 24 probes. The missions were sent to sample formations and areas which typified the common observed features of the lunar surface. Drive tubes were used to extract samples from beneath the surface in order to study the relationship between the regolith and the bedrock, as well as to identify the processes that formed the regolith, which is regarded as the prime source of raw materials for early lunar industrial activities. Regolith origins are now understood to be destructive processes of comminution and constructional processes of agglutinate formation. Mixing occurs on the local scale, although lateral transport is inefficient on the moon. The usual contents of the fraction of regolith less than 10 microns in diameter are Al2O3, CaO, Na2O, K2O, light REE, and Th.

  17. Multielement chemical and statistical analyses from a uranium hydrogeochemical and stream-sediment survey in and near the Elkhorn Mountains, Jefferson County, Montana; Part II, Stream sediments

    USGS Publications Warehouse

    Suits, V.J.; Wenrich, K.J.

    1982-01-01

    Fifty-two stream-sediment samples, collected from an area south of Helena, Jefferson County, Montana, were sieved into two size fractions (50 ppm for the fine fraction) were encountered in samples from the Warm Springs Creek drainage area, along Prickly Pear Creek near Welmer and Golconda Creeks and along Muskrat Creek. All groups showed a significant correlation at the 99 percent confidence level (r between 0.73 and 0.77) between U and Th. Uranium was found to correlate significantly only with Th (as mentioned above) and with -Ni in the fine fraction of the volcanics group. U correlates significantly with -Al2O3, Ba, organic C, -K2O, -Sr and Y in both size fractions for the Boulder batholith. Correlations between U and each of several elements differ for the fine and coarse fractions of the Boulder batholith group, suggesting that the U distribution in these stream sediments is in large part controlled by grain size. Correlations were found between U and CaO, Cr, Fe203, -Na2O, Sc, -SiO2, TiO2, Yb and Zr in the coarse fraction but not in the fine fraction. U correlates weakly (to the 90% confidence level, crc<.37) with -Co and -Cu in the fine but not the coarse fraction. These results are compared to a previous study in the northern Absaroka mountains. Correlation coefficients between all other elements determined from these samples are also shown in Tables 12 to 15.

  18. A comparison of the chemical composition and bioactive ingredients of the Chinese medicinal mushroom DongChongXiaCao, its counterfeit and mimic, and fermented mycelium of Cordyceps sinensis

    Microsoft Academic Search

    Tai-Hao Hsu; Li-Hua Shiao; Chienyan Hsieh; Der-Ming Chang

    2002-01-01

    The Chinese herbal drug DongChongXiaCao, a medicinal and edible mushroom originating from the fungus Cordyceps sp., has been developed into health foods. Counterfeit and mimic types are frequently found in markets. Mycelial preparations of Cordyceps sinensis, via submerged fermentation, have been commercialized and also named DongChongXiaCao. This investigation endeavours to characterize the proximate composition, amino acid profiles, and contents of

  19. MgO and CaO stabilized ZrO 2 thin films obtained by Metal Organic Chemical Vapor Deposition

    Microsoft Academic Search

    Giovanni Carta; Naida El Habra; Gilberto Rossetto; Pierino Zanella; Maurizio Casarin; Davide Barreca; Cinzia Maragno; Eugenio Tondello

    2007-01-01

    Metal Organic Chemical Vapor Deposition of cubic stabilized zirconia was investigated by the addiction of the alkaline-earth oxides MgO and CaO. While Cp2ZrMe2 [(Cp=–C5H5, Me=–CH3)] was used as precursor for ZrO2, two different Mg compounds were tested for the MgO deposition, namely bis-(?5-methylcyclopentadienyl)Mg(II) [(Mg(Cp-Me)2] and bis-(2,2,6,6-tetramethyl-3,5-heptanedionate)(tetramethylethylenediamine)Mg(II) [Mg(tmhd)2·tmeda]. Bis-(2,2,6,6-tetramethyl-3,5-heptanedionate)(triethyleneglycoldimethylether)Ca(II) [Ca(tmhd)2·triglyme] was used for CaO growth. Depositions were carried out on fused

  20. The effect of Al2O3, CaO, Cr2O3 and MgO on devitrification of silica

    NASA Technical Reports Server (NTRS)

    Zaplatynsky, Isidor

    1988-01-01

    The effect of doping on devitrification of vitreous silica was studied at 1100, 1200, and 1300 C. Dispersion of dopants on a molecular scale was accomplished via a sol-gel technique. All dopants accelerated the devitrification of silica but to different degrees. The most active was CaO followed by MgO, Al2O3, and Cr2O3. Pure silica and silica containing Cr2O3 and Al2O3 devitrified to alpha-cristobalite only, whereas silica doped with CaO and MgO produced alpha-quartz and alpha-cristobalite. It appears that prolonged heat treatment would cause alpha-quartz to transform to alpha-cristobalite.

  1. Role of Y{sub 2}O{sub 3}, CaO, MgO additives on structural and microstructural behavior of zirconia/mullite aggregates

    SciTech Connect

    Mishra, D. K.; Prusty, Sasmita; Mohapatra, B. K.; Singh, S. K.; Behera, S. N. [Advanced Materials Technology Department, CSIR-Institute of Minerals and Materials Technology, Bhubaneswar 751 013, Odisha (India); Geological Survey of India, Alandi Road, Pune 411 006, Maharashtra (India); Mineralogy Department, CSIR-Institute of Minerals and Materials Technology, Bhubaneswar 751 013, Odisha (India); Advanced Materials Technology Department, CSIR-Institute of Minerals and Materials Technology, Bhubaneswar 751 013, Odisha (India); National Institute of Science and Technology (NIST), Berhampur 761 008, Odisha (India)

    2012-07-23

    Zirconia mullite (MUZ), Y{sub 2}O{sub 3}-MUZ, CaO-MUZ and MgO-MUZ composites, synthesized through plasma fusion technique, are becoming important due to their commercial scale of production within five minutes of plasma treatment from sillimanite, zircon and alumina mixture. The X-ray diffraction studies reveal the monoclinic zirconia phase in MUZ composite whereas mixed monoclinic, tetragonal and cubic phases of zirconia have been observed in Y{sub 2}O{sub 3}, CaO, MgO added MUZ composites. The Y{sub 2}O{sub 3}, CaO and MgO additives act as sintering aids to favour the transformation and stabilisation of tetragonal and cubic zirconia phases at room temperature. These additives also play a key role in the development of various forms of microstructure to achieve dense MUZ composites.

  2. End to end assembly of CaO and ZnO nanosheets to propeller-shaped architectures by orientation attachment approaches

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Liu, Fang

    2015-06-01

    Inspired by the agitation effect of propellers, heterogeneous propeller- shaped CaO/ZnO architectures were assembled in aqueous solution. Preferred nucleation and growth of CaO and ZnO nuclei resulted in their hexagonal nanosheets, and they were end to end combined into propeller-shaped architectures by oriented rotation and attachment reactions. When propeller-shaped CaO/ZnO product was used as solid base catalyst to synthesize biodiesel, a high biodiesel yield of 97.5% was achieved. The predominant exposure of active O2- on CaO(0 0 2) and ZnO(0 0 0 2) planes in propeller-shaped CaO/ZnO, led to good catalytic activity and high yield of biodiesel.

  3. Comparison of phosgene, chlorine, and hydrogen chloride as reagents for converting molten CaO. CaCl/sub 2/ to CaCl/sub 2/

    SciTech Connect

    Fife, K.W.

    1985-01-01

    One method at Los Alamos for preparing impure plutonium metal from the impure oxide is by batch reduction with calcium metal at 850/sup 0/C in a CaCl/sub 2/ solvent. The solvent salt from this reduction is currently discarded as low-level radioactivity waste only because it is saturated with the CaO byproduct. We have demonstrated a pyrochemical technique for converting the CaO to CaCl/sub 2/ thereby incorporating solvent recycling into the batch reduction process. We will discuss the effectiveness of HCl, Cl/sub 2/, and COCl/sub 2/ as chlorinating agents and recycling actual spent process solvent salts. 6 refs., 8 figs.

  4. Comparison of phosgene, chlorine, and hydrogen chloride as reagents for converting molten CaO. CaCl/sub 2/ to CaCl/sub 2/

    SciTech Connect

    Fife, K.W.; Bowersox, D.F.; McCormick, E.D.

    1985-09-01

    One method used at Los Alamos for preparing impure plutonium metal from the impure oxide is batch reduction with calcium metal at 850/sup 0/C in a CaCl/sub 2/ solvent. The solvent salt from this reduction is currently discarded as low-level radioactive waste only because it is saturated with the CaO by-product. We have demonstrated a pyrochemical technique for converting the CaO to CaCl/sub 2/, thereby incorporating solvent recycle into the batch reduction process. We discuss the effectiveness of HCl, Cl/sub 2/, and COCl/sub 2/ as chlorinating agents and present initial data on regenerating and recycling actual, spent-solvent salts. 6 refs., 8 figs., 1 tab.

  5. Effect of adding CaO to ZrO 2 support on nickel catalyst activity in dry reforming of methane

    Microsoft Academic Search

    Jorge D. A. Bellido; José E. De Souza; Jean-Claude M’Peko; Elisabete M. Assaf

    2009-01-01

    Nickel catalysts with a load of 5wt% Ni, supported on pure ZrO2 and ZrO2 stabilized with 4, 8 and 14mol% CaO, were prepared by the polymerization method. The samples were characterized by X-ray diffraction (XRD), temperature-programmed reduction with hydrogen (TPR-H2), specific surface area (BET) and impedance spectroscopy (IS) and tested in the carbon dioxide reforming of methane. The XRD patterns

  6. Quantitative evaluation of antibacterial activities of metallic oxide powders (ZnO, MgO and CaO) by conductimetric assay

    Microsoft Academic Search

    J. Sawai

    2003-01-01

    Antibacterial activities of metallic oxide (ZnO, MgO and CaO) powders against Staphylococcus aureus and Escherichia coli were quantitatively evaluated by measuring the change in electrical conductivity of the growth medium caused by bacterial metabolism (conductimetric assay). The obtained conductivity curves were analyzed using the growth inhibition kinetic model proposed by Takahashi for calorimetric evaluation, and the metallic oxides were determined

  7. Biomass gasification with steam in fluidized bed: Effectiveness of CaO, MgO, and CaO-MgO for hot raw gas cleaning

    Microsoft Academic Search

    Jesús Delgado; María P. Aznar; José Corella

    1997-01-01

    The upgrading of the raw hot gas from a bubbling fluidized bed biomass gasifier is studied using cheap calcined minerals or rocks downstream from the gasifier. Biomass gasification is made with steam (not air) at 750--780 C and about 0.5--1.0 kg of biomass\\/h. Calcined solids used are dolomite (MgO-CaO), pure calcite (CaO), and pure magnesite (MgO). Variables studied have been

  8. The rates of desulfurization of liquid iron by solid CaO and CaO-saturated liquid iron oxide at 1600‡c

    NASA Astrophysics Data System (ADS)

    Saelim, A.; Gaskell, D. R.

    1983-06-01

    The rates of desulfurization of Fe-O-S melts by CaO crucibles and by CaO-saturated liquid iron oxide have been measured at 1600 ‡C. It was found that irons containing 1.62 wt pct and 0.64 wt pct sulfur and 0.070 wt pct oxygen are desulfurized by a reaction with the containing CaO crucible which does not involve the formation of a CaS product layer. The rate of desulfurization reaction is controlled by diffusion of sulfur in the iron melt, and a value of 6.7 ±1.7 × 10-5 cm2 per second was obtained for the diffusion coefficient of sulfur in liquid iron. Iron containing 0.088 wt pct sulfur and 0.070 wt pct oxygen is not desulfurized by solid CaO. The rate of desulfurization of liquid iron containing 0.088 wt pct sulfur and 0.070 wt pct oxygen by CaO-saturated liquid iron oxide is significantly greater than that calculated on the assumption of diffusion control in the metal phase, and evidence is presented in support of speculation that the reaction rate is enhanced by Marangoni turbulence at the slag-metal interface. The addition of 4 wt pct CaF2 to the CaO-saturated liquid iron oxide has no influence on the rate of desulfurization of the melt.

  9. CaO insulator coatings and self-healing of defects on V-Cr-Ti alloys in liquid lithium system

    SciTech Connect

    Park, J.H.; Kassner, T.F.

    1995-09-01

    Electrically insulating and corrosion-resistant coatings are required at the liquid metal/structural interface in fusion first-wall/blanket applications. Electrical resistance of CaO coatings that were produced on V-5%Cr-5%Ti by exposure of the alloy to liquid Li containing 0.5-85 wt.% dissolved Ca was measured as a function of time at temperatures between 250 and 600{degrees}C. The solute element, Ca in liquid Li, reacted with the alloy substrate at 400-420{degrees}C to produce a CaO coating. Resistance of the coating layer measured in-situ in liquid Li was {approx}10{sup 6} {Omega} at 400{degrees}C. Thermal cycling between 300 and 700{degrees}C changed the coating layer resistance, which followed insulator behavior. These results suggest that thin homogeneous coatings can be produced on variously shaped surfaces by controlling the exposure time, temperature, and composition of the liquid metal. The technique can be applied to various shapes (e.g., inside/outside of tubes, complex geometrical shapes) because the coating is formed by liquid-phase reaction. Examination of the specimens after cooling to room temperature revealed no spallation, but homogeneous crazing cracks were present in the CaO coating. Additional tests to investigate the in-situ self-healing behavior of the cracks indicated that rapid healing occurred at {>=}360{degrees}C.

  10. New data on selected Ivory Coast tektites

    USGS Publications Warehouse

    Cuttitta, F.; Carron, M.K.; Annell, C.S.

    1972-01-01

    Fourteen Ivory Coast tektites exhibit a range of bulk indices of refraction of 1.5156 to 1.5217 ?? 0.0004 and of bulk specific gravities of 2.428 to 2.502 ??0.005. Seven of these Ivory Coast (IVC) tektites were analyzed for major and minor element content. Compared to tektites from other strewn fields, their SiO2 content is low (67.2-69.1 %), A12O3 relatively high (15.8-16.8 %), and total iron relatively high but with a more restricted range (6.3-6.8 % as FeO). Their lime content is low (0.71-1.35%) compared to Australasian tektites but their MgO CaO ratio (about 3.1) is unusually high. All other tektite groups have Na2O K2O ratios less than unity, but the Na2O K2O ratio of the IVC tektites is slightly greater than unity. Their K Rb ratios range from 200 to 256 and average 227, which is higher than those determined for Australasian tektites, but similar to some obtained for moldavites. The Li content (41-48 ppm) is about the same as that of the Australasian tektites, but the Cs and Rb are lower, being 1.9 to 2.9 and 57 to 86 ppm, respectively. The IVC tektites are high in Cr (260-375 ppm), Co (19-25 ppm) and Ni (101-167 ppm), and particularly in Pb (<10-18 ppm), Cu (13-21 ppm) and Ga (14-23 ppm). The high Cr Ni ratios of the IVC tektites (range 2-3.6) are similar to those found for australites, philippinites and thailandites, but not the javanites and indochinites. Evaluation of these and other reported data show that compositional similarities between the IVC tektites and green or black Bosumtwi Crater glasses strongly support the hypothesis of a common impact origin-i.e. the Bosumtwi Crater site. Comparison of the IVC tektite composition with those of returned lunar materials (gabbros, basalts, breccia and soils) do not support a lunar origin for the Ivory Coast tektites. ?? 1972.

  11. The Influence of Melt Composition and Dissolved Water on the Melt-Vapor Surface Tension of Dacite and Rhyolite Magma

    NASA Astrophysics Data System (ADS)

    Mangan, M.; Sisson, T.

    2004-12-01

    Melt-vapor surface tension (? ) is a poorly known quantity, yet it plays a critical role in many volcanic processes. In this study, we provide new data for ? of hydrous natural dacite and rhyolite melt at 200 MPa, 800-1055° C, and 4.8-7.7 wt% H2O using results from high temperature and pressure decompression experiments (this study; Mangan and Sisson, 2000; Mourtada-Bonnefoi and Laporte, 2002; 2004) and classical nucleation theory. The solutions give values for ? that vary inversely with dissolved H2O by 0.025 (± 0.009) J/m2 per wt% H2O. Combining our results with data from hydrous haplogranite and rhyodacite (Epel'baum et al., 1973; Bagdassarov et al., 2000) reveals that melt-vapor surface tension also varies inversely with the concentration of mafic melt components (e.g., CaO, FeOtotal, MgO). At constant H2O content, ? increases by 0.70 (± 0.53) J/m2 per tenth increment increase in the melt felsic index (FI = Na2O+K2O/Na2O+K2O+CaO) from FI ˜ 0.75 (dacite) to FI ˜ 1.0 (haplogranite). To understand these results, we consider the thermodynamic definition of ? , i.e., the work per unit surface area to create an interface between two phases. It can be expressed as: ? dA = ? dissociation - ? interaction. The ? dissociation term is the work done to dissociate molecules from the bulk melt for incorporation in a diffuse, lower density interfacial zone only a few molecular layers thick. In contrast, the work of interaction, ? interaction, is work made available as a result of across-interface attractions between gas and melt molecules. Increasing the concentration of dissolved H2O and other network modifiers (e.g., Ca, Fe, and Mg) influence the balance of work terms as (1) the ? dissociation declines due to lowered cohesion of the disrupted melt structure, and (2) the ? interaction increases because enhanced molecular diversity supports more numerous and varied interfacial zone attractions. The net effect of decreased ? dissociation and increased ? interaction is a decrease in ? . Additional, systematic data on the variation of ? in natural hydrous melts are needed before the volcanic implications can be fully explored. Nevertheless, it is evident from the data in hand that surface tension, much like melt density and viscosity, can and should be treated as a variable. Cooling, crystallization, and vapor exsolution impart a time-dependency to ? that must be accounted for in modeling volcanic processes.

  12. Spectroscopic Characterization of a Multiband Complex Oxide: Insulating and Conducting Cement 12CaO·7Al?O?

    SciTech Connect

    McLeod, John A.; Buling, A.; Kurmaev, Ernst Z.; Sushko, Petr V.; Neumann, N.; Finkelstein, L. D.; Kim, S. W.; Hosono, H.; Moewes, Alexander

    2012-01-13

    Natural 12CaO·7Al?O? (C12A7) is a wide band gap insulator, but conductivity can be realized by introducing oxygen deficiency. Currently, there are two competing models explaining conductivity in oxygen-deficient C12A7, one involving the electron transfer via a “cage conduction band” inside the nominal band gap, the other involving electron hopping along framework lattice sites. To help resolve this debate, we probe insulating and conducting C12A7 with x-ray emission, x-ray absorption, and x-ray photoemission spectroscopy, which provide a full picture of both the valence and conduction band edges in these materials. Thesemeasurements suggest the existence of a narrow conduction band between themain conduction and valence bands common in both conducting and insulating C12A7 and support the theory that free electrons in oxygen-deficient C12A7 occupy the low-energy states of this narrow band. Our measurements are corroborated with density functional theory calculations.

  13. Geological control of canopy structure and function in Panamanian forests as identified by CAO-AToMS

    NASA Astrophysics Data System (ADS)

    Higgins, M.; Asner, G. P.; Martin, R. E.; Knapp, D. E.

    2012-12-01

    Geological formations and their edaphic properties are known to control plant species composition in tropical forests. It has been speculated that these edaphic and compositional patterns might also be translated into functional patterns, but this has been difficult to test due to a lack of broad-scale but detailed canopy structural and functional data. Here we use the Carnegie Airborne Observatory (CAO) Airborne Taxonomic Mapping System (AToMS), which combines a 480-band visible-to-shortwave imaging spectrometer (VSWIR) with dual waveform LiDAR, to generate ultra-high resolution data on geomorphology, canopy structure, and canopy chemistry for forests in the vicinity of the Panama Canal. Using these remotely-sensed data, in conjunction with field data on soils and plant species composition, we demonstrate that geological formations regulate forest structure and chemistry in these forests via changes in soils and plant species composition. These chemical properties, moreover, correspond to canopy functional properties including photosynthetic investment and anti-herbivore defenses. Together, our findings indicate that forest canopy structure and function in these forests are an expression their geological history, over which variations due to contemporary variables such as climate are overlaid.

  14. A Statistical Framework for Calculating and Assessing Compositional Linear Trends Within Fault Zones: A Case Study of the NE Block of the Clark Segment, San Jacinto Fault, California, USA

    NASA Astrophysics Data System (ADS)

    Rockwell, Brian G.; Girty, Gary H.; Rockwell, Thomas K.

    2014-11-01

    Utilizing chemical data derived from the various fault zone architectural components of the Clark strand of the San Jacinto fault, southern California, USA, we apply for the first time non-central principal component analysis to calculate a compositional linear trend within molar A-CN-K space. In this procedure A-CN-K are calculated as the molar proportions of Al2O3 (A), CaO* + Na2O (CN), and K2O (K) in the sum of molar Al2O3, Na2O, CaO*, and K2O. CaO* is the molar CaO after correction for apatite. We then derive translational invariant chemical alteration intensity factors, t, for each architectural component through orthogonal projection of analyzed samples onto the compositional linear trend. The chemical alteration intensity factor t determines the relative change in composition compared to the original state (i.e., the composition of the altered wall rocks). It is dependent on the degree of intensity to which the process or processes responsible for the change in composition of each architectural component has been active. These processes include shearing, fragmentation, fluid flow, and generation of frictional heat. Non-central principal component analysis indicates that principal component 1 explains 99.7 % of the spread of A-CN-K data about the calculated compositional linear trend (i.e., the variance). The significance level for the overall one-way analysis of variance (ANOVA) is 0.0001. Such a result indicates that at least one significant difference across the group of means of t values is different at the 95 % confidence level. Following completion of the overall one-way ANOVA, the difference in means t test indicated that the mean of the t values for the fault core are different than the means obtained from the transition and damage zones. In contrast, at the 95 % confidence level, the means of the t values for the transition and damage zones are not statistically distinguishable. The results of XRD work completed during this study revealed that the <2 µm fraction is composed primarily of illite/smectite with ~15 % illite in the damage zone, of illite/smectite with ~30 % illite in the transition zone, and of discreet illite with very minor smectite in the fault core. These changes parallel the increasing values of the chemical alteration intensity factors (i.e., t). Based on the above results, it is speculated that when fault zones are derived from tonalitic wall rocks at depths of ~400 ± 100 m, the onset of the illite/smectite to illite conversion will occur when t values exceed 0.20 ± 0.12, the average chemical alteration intensity factor calculated for the transition zone. Under such conditions during repeated rupturing events, frictional heat is produced and acidic fluids with elevated temperatures (? ~125 °C) are flushed through the fault core. Over time, the combination of shearing, fragmentation, and frictionally elevated temperatures eventually overcomes the kinetic barrier for the illite/smectite to illite transition. Such settings and processes are unique to fault zones, and as a result, they represent an underappreciated setting for the development of illite from illite/smectite. The success of non-central principal component analysis in this environment offers the first statistically rigorous methodology for establishing the existence of compositional linear trends in fault zones. This method also derives quantifiable alteration intensity factors that could potentially be used to compare the intensity of alteration at different segments of a fault, as well as offer a foundation to interpret the potential driving forces for said alteration and differences therein.

  15. The dissolution of natural and artificial dusts in glutamic acid

    NASA Astrophysics Data System (ADS)

    Ling, Zhang; Faqin, Dong; Xiaochun, He

    2014-08-01

    This article describes the characteristics of natural dusts, industrial dusts, and artificial dusts, such as mineral phases, chemical components, morphological observation and size. Quartz and calcite are the main phases of natural dusts and industrial dusts with high SiO2 and CaO and low K2O and Na2O in the chemical composition. The dissolution and electrochemical action of dusts in glutamic acid liquor at the simulated human body temperature (37 °C) in 32 h was investigated. The potential harm that the dust could lead to in body glutamic acid acidic environment, namely biological activity, is of great importance for revealing the human toxicological mechanism. The changes of pH values and electric conductivity of suspension of those dusts were similar, increased slowly in the first 8 h, and then the pH values increased rapidly. The total amount of dissolved ions of K, Ca, Na, and Mg was 35.4 to 429 mg/kg, particularly Ca was maximal of 20 to 334 mg/kg. The total amount of dissolved ions of Fe, Zn, Mn, Pb, and Ba was 0.18 to 5.59 mg/kg and in Al and Si was 3.0 to 21.7 mg/kg. The relative solubility order of dusts in glutamic acid is wollastonite > serpentine > sepiolite, the cement plant industrial dusts > natural dusts > power plant industrial dusts. The wollastonite and cement plant industrial dusts have the highest solubility, which also have high content of CaO; this shows that there are a poorer corrosion-resisting ability and lower bio-resistibility. Sepiolite and power plant industrial dusts have lowest solubility, which also have high content of SiO2; this shows that there are a higher corrosion-resisting ability and stronger bio-resistibility.

  16. The dissolution of natural and artificial dusts in glutamic acid

    NASA Astrophysics Data System (ADS)

    Ling, Zhang; Faqin, Dong; Xiaochun, He

    2015-06-01

    This article describes the characteristics of natural dusts, industrial dusts, and artificial dusts, such as mineral phases, chemical components, morphological observation and size. Quartz and calcite are the main phases of natural dusts and industrial dusts with high SiO2 and CaO and low K2O and Na2O in the chemical composition. The dissolution and electrochemical action of dusts in glutamic acid liquor at the simulated human body temperature (37 °C) in 32 h was investigated. The potential harm that the dust could lead to in body glutamic acid acidic environment, namely biological activity, is of great importance for revealing the human toxicological mechanism. The changes of pH values and electric conductivity of suspension of those dusts were similar, increased slowly in the first 8 h, and then the pH values increased rapidly. The total amount of dissolved ions of K, Ca, Na, and Mg was 35.4 to 429 mg/kg, particularly Ca was maximal of 20 to 334 mg/kg. The total amount of dissolved ions of Fe, Zn, Mn, Pb, and Ba was 0.18 to 5.59 mg/kg and in Al and Si was 3.0 to 21.7 mg/kg. The relative solubility order of dusts in glutamic acid is wollastonite > serpentine > sepiolite, the cement plant industrial dusts > natural dusts > power plant industrial dusts. The wollastonite and cement plant industrial dusts have the highest solubility, which also have high content of CaO; this shows that there are a poorer corrosion-resisting ability and lower bio-resistibility. Sepiolite and power plant industrial dusts have lowest solubility, which also have high content of SiO2; this shows that there are a higher corrosion-resisting ability and stronger bio-resistibility.

  17. Mapping the geographic distribution of canopy species communities in lowland Amazon rainforest with CAO-AToMS (Invited)

    NASA Astrophysics Data System (ADS)

    Feret, J.; Asner, G. P.

    2013-12-01

    Mapping regional canopy diversity will greatly advance our understanding as well as the conservation of tropical rainforests. Changes in species composition across space and time are particularly important to understand the influence of climate, human activity and environmental factors on these ecosystems, but to date such monitoring is extremely challenging and is facing a scale gap between small-scale, highly detailed field studies and large-scale, low-resolution satellite observations. Advances were recently made in the field of spectroscopic imagery for the estimation of canopy alpha-diversity, and an original approach based on the segmentation of the spectral space proved its ability to estimate Shannon diversity index with unprecedented accuracy. We adapted this method in order to estimate spectral dissimilarity across landscape as a proxy for changes in species composition. We applied this approach and mapped species composition over four sites located in lowland rainforest of Peruvian Amazon. This study was based on spectroscopic imagery acquired using the Carnegie Airborne Observatory (CAO) Airborne Taxonomic Mapping System (AToMS), operating a unique sensor combining the fine spectral and spatial resolution required for such task. We obtained accurate estimation of Bray-Curtis distance between pairs of plots, which is the most commonly used metric to estimate dissimilarity in species composition (n=497 pairs, r=0.63). The maps of species composition were then compared to topo-hydrographic properties. Our results indicated a strong shift in species composition and community diversity between floodplain and terra firme terrain conditions as well as a significantly higher diversity of species communities within Amazonian floodplains. These results pave the way for global mapping of tropical canopy diversity at fine geographic resolution.

  18. Landscape-scale tropical forest dynamics: Relating canopy traits and topographically derived hydrologic indices in a floodplain system using CAO-AToMS

    NASA Astrophysics Data System (ADS)

    Chadwick, K.; Asner, G. P.

    2012-12-01

    The geomorphology of floodplains in the humid tropics has been used to infer basic classifications of forest types. However, analysis of the landscape-scale topographic and hydrologic patterns underpinning spatial variation in forest composition and function remain elusive due to the sparse coverage of forest plots, coarse resolution remotely sensed data, and the challenges of collecting first order hydrologic data. Airborne remote measurements provide an opportunity to consider the relationship between high-resolution topographic and derived hydrologic environmental gradients, and forest canopy characteristics with important cascading effects on ecosystem function and biosphere-atmosphere interactions. In 2011, the Carnegie Airborne Observatory (CAO) Airborne Taxonomic Mapping System (AToMS) was used to map a large section of the Los Amigos Conservation Concession harboring largely intact lowland humid tropical forest in the southwestern Peruvian Amazon. The CAO Visible-Shortwave Imaging Spectrometer (VSWIR) collected 480-band high-fidelity imaging spectroscopy data of the forest canopy, while its high-resolution dual waveform LiDAR captured information on canopy structure and the underlying terrain. The data were used to quantify relationships between topographic and hydrologic gradients and forest functional traits. Results suggest strong local hydrogeomorphic control over vegetation spectral properties with known relationships to canopy functional traits, including pigment and nutrient concentrations and light capture, as well as canopy structural characteristics, including vegetation height, understory plant cover, and aboveground biomass. Data from CAO-AToMS reveals local-scale patterns in environmental conditions and ecological variation that meets or exceeds the variation previously reported across ecosystems of the Western Amazon Basin.

  19. Heavy doping of H{sup -} ion in 12CaO.7Al{sub 2}O{sub 3}

    SciTech Connect

    Hayashi, Katsuro, E-mail: k-hayashi@lucid.msl.titech.ac.jp [Center for Secure Materials, Materials and Structures Laboratory, Tokyo Institute of Technology, R3-34, 4295 Nagatsuta, Yokohama 226-8503 (Japan)

    2011-06-15

    12CaO.7Al{sub 2}O{sub 3} (C12A7, mayenite), which has a nanoscale porous structure that can accommodate extraframework species such as hydride (H{sup -}), oxide (O{sup 2-}), hydroxide (OH{sup -}) ions, and electrons, has been doped with H{sup -} ions to investigate its effects as dominant extraframework species. Chemical doping with CaH{sub 2} enables the concentration of H{sup -} ions to reach almost the theoretical maximum. The concentration of H{sup -} ions is characterized by optical absorption intensity ascribed to photoionization of H{sup -} ions, and {sup 1}H magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy. Persistent electron generation, which is accompanied by the formation of an F{sup +} absorption band and electrical conductivity, by irradiation with ultraviolet light at room temperature increases as the H{sup -} ion doping increases until it reaches half the theoretical maximum and then decreases as the H{sup -} ion concentration increases further. This dependence indicates that both H{sup -} and O{sup 2-} ions are necessary for the generation of persistent electrons. - Graphical abstract: CaH{sub 2} reduction markedly enhances H{sup -} ion doping in 12CaO.7Al{sub 2}O{sub 3}. The H{sup -} ion incorporation is evaluated using optical absorption and {sup 1}H-MAS-NMR spectra. Both H{sup -} and O{sup 2-} ions are responsible for photogeneration of electrons. Highlights: > CaH{sub 2} reduction markedly enhances H{sup -} ion doping in 12CaO.7Al{sub 2}O{sub 3}. {yields}The H{sup -} ion incorporation is evaluated using optical absorption and {sup 1}H-MAS-NMR spectra. > Both H{sup -} and O{sup 2-} ions are responsible for photogeneration of electrons.

  20. Full potential calculation of structural, electronic and elastic properties of alkaline earth oxides MgO, CaO and SrO

    NASA Astrophysics Data System (ADS)

    Baltache, H.; Khenata, R.; Sahnoun, M.; Driz, M.; Abbar, B.; Bouhafs, B.

    2004-02-01

    A theoretical study of structural and electronic properties of MgO, CaO and SrO is presented using the full-potential linearized augmented plane wave method. In this approach, the local density approximation was used for exchange-correlation potentials. Results are given for lattice constant, bulk modulus and its pressure derivative in both NaCl-(B1) and CsCl-(B2) structures. Band structure, density of states and band gap-pressure coefficients in NaCl-(B1) phase are also given. The results are compared with previous calculations and with experimental measurements.

  1. [Textual research on Guang dong xin yu (New Sayings of Guangdong) quoted in Ben cao gang mu shi yi (Supplements to Compendium of Materia Medica].

    PubMed

    Zhang, Ruixian; Zhang, Wei; Li, Jian; Liang, Fei

    2014-05-01

    Altogether 15 terms for Guang dong xin yu (New Sayings of Guangdong) were used in Ben cao gang mu shi yi (Supplements to Compendium of Materia Medica), including Yue yu (Cantonese sayings), Chong yu (Sayings from Insect Drug), Jie yu (Sayings from Crustacean Drug), Xin yu (New Sayings), Yue hai xiang yu (Fragrant Sayings from Cantonese Region), Yue zhi mu yu (Sayings from Plants in Cantonese Annals), Guang dong suo yu (Trivial Sayings from Guangdong), Yue shan lu (Records of Cantonese Mountains), Yue lu (Cantonese Records), Jiao guang lu (Joint Guangdong Records), Yue cao zhi (Records of Cantonese Grasses), Guang guo lu (Records of Guangdong Fruits), Nan yue suo ji (Trivial Records of Southern Canton), Guang zhi (Guangdong Records), Yue zhi (Cantonese Records) etc. dealing with 57 sorts of drugs (with individual overlapping ones), the author of Xin yu was Qu Dajun, a surviving fogy of the Ming Dynasty actively involved in the activities to restore the old dynasty and resist the Qing Dynasty, and was persecuted in the literary inquisition in which his works were burnt so that Zhao Xuemin, when quoting his texts, had to go in a roundabout way. PMID:25208840

  2. Reaction of sodium calcium borate glasses to form hydroxyapatite

    Microsoft Academic Search

    Xue Han; Delbert E. Day

    2007-01-01

    This study investigated the transformation of two sodium calcium borate glasses to hydroxyapatite (HA). The chemical reaction\\u000a was between either 1CaO · 2Na2O · 6B2O3 or 2CaO · 2Na2O · 6B2O3 glass and a 0.25 M phosphate (K2HPO4) solution at 37, 75 and 200 °C. Glass samples in the form of irregular particles (125–180 ?m) and microspheres (45–90 and\\u000a 125–180 ?m) were used in order to understand the reaction mechanism. The effect

  3. Influence of CaO and SiO2 co-doping on the magnetic, electrical properties and microstructure of a Ni–Zn ferrite

    NASA Astrophysics Data System (ADS)

    Hajalilou, A.; Hashim, M.; Ebrahimi-Kahrizsangi, R.; Sarami, N.

    2015-04-01

    Effect of CaO and SiO2 additions on the grain growth and magnetic and electrical properties of a Ni–Zn ferrite was studied. The common oxides (x = 0.4CaO + 0.8SiO2) were added in different moles (x = 0, 0.02, 0.06, 0.012, 0.24 and 0.48) to Fe2O3, Zn, and NiO. The mixed powders were mechanically alloyed for 12?h using a high energy ball mill before heating at 1200?°C for 240?min. The products were characterized by x-ray diffraction (XRD), field emission scanning electron microscopy, energy-dispersive x-ray spectroscopy, vibrating sample magnetometer and static hysteresisgraph, and later by an impedance analyzer with a frequency range from 1?MHz to 1.8?GHz. The XRD results indicate a formation of single phase spinel structure in all the samples. The average grain size was affected by the additive contents so that their sizes grew, up to x = 0.06, and after that their sizes reduced from 0.631 to 0.371?? at x = 0.48. The experimental density of the samples displayed an upward trend for x < 0.06, increasing from 5.39?g?cm?3 (x = 0) to 5.51?g?cm?3 (x = 0.06): afterwards, their values presented a downward trend, reducing to 4.01?g?cm?3 at x = 0.48. Magnetic behaviors such as saturation magnetization ({{M}s} ) and induction magnetization ({{B}s} ) degraded as well as the real permeability of the samples by increasing the x content. The loss factor i.e. hysteresis loss also remarkably decreased by accumulation of SiO2 and CaO in the grain boundaries. The electrical resistivity was determined in the order of 6.9? × ?1010???cm for x = 0 and 6.4? × ?1011???cm for x = 0.48. Therefore, low relative loss factor and high resistivity make these ferrites particularly useful as inductor and transformer materials for high frequency applications.

  4. Otology research department Vanderbilt University Nashville, Tennessee daniel.schurzig@vanderbilt.edu http://www.vanderbilt.edu/CAOS Mechanical Engineering Department Vanderbilt University Nashville, Tennessee http://research.vuse.vanderbilt.edu/MEDLa

    E-print Network

    Webster III, Robert James

    Assist Rad and Surg, 4(3): p. 273-280. [3] Majdani O, et al., "Time of cochlear implant surgery Cochlear Implantation D. Schurzig, Z. W. Smith, D. C. Rucker, R. F. Labadie and R. J. Webster III CAOS lab of Cochlear Implant Child 2010 Motivation Nucleus 24 Contour Advance Electrode, Cochlear Co., Inc. Hi

  5. [Preliminary textual research on Zhijintang Sanctum re-revised version of Jinling edition of Ben cao gang mu (Compendium of Materia Medica)].

    PubMed

    Zheng, Jinsheng

    2014-03-01

    The Zhijintang Sanctum version of the re-revised edition of Jinling edition of Ben cao gang mu (Compendium of Materia Medica)collected by Zhao Huiyuan of Baihe, Henan Province in 2008 was opted as one of the third batch of the National Directory of Rare Ancient Worksin 2010. On the second cover page (patent page), it is recorded as"Original Jiangxi version". However, it is investigated to find that most of its paper sheets were reprinted after the original Jinling version, only scores of paper sheets were supplemented block-printed, including the additional block-printed second preface and Li Jianyuan's submitted report of the Jiangxi version, the re-revised time of which should be after the Jiangxi edition, or 1603. The exact time can be determined only by checking it carefully against another Jinling re-revised version (the Sheyuantang Sanctum edition). PMID:24989810

  6. Effect of CaO doping on corrosion resistance of Cu\\/(NiFe 2 O 4 -10NiO) cermet inert anode for aluminum electrolysis

    Microsoft Academic Search

    Yan-qing Lai; Li-feng Huang; Zhong-liang Tian; Jia-wei Wang; Gang Zhang; Yong Zhang

    2008-01-01

    The CaO-doped Cu\\/(NiFe2O4-10NiO) cermet inert anodes were prepared by the cold isostatic pressing-sintering process, and their corrosion resistance\\u000a to Na3AlF6-K3AlF6-Al2O3 melt was studied. The results show that the relative density of 5Cu\\/(NiFe2O4-10NiO) cermet sintered at 1 200 °C increases from 82.83% to 97.63% when 2% CaO (mass fraction) is added. During the electrolysis,\\u000a the relative density of cermet inert anode

  7. Double-layer glass-ceramic coatings on Ti6Al4V for dental implants

    Microsoft Academic Search

    E. Verné; C. Fernández Vallés; C. Vitale Brovarone; S. Spriano; C. Moisescu

    2004-01-01

    Double-layer bioactive glass-ceramic coatings were prepared on Ti–6Al–4V substrates by dipping and firing. A SiO2–CaO–Na2O–MgO–P2O5–K2O (SCP) based glass was used as first layer in direct contact with the metallic substrate and a SiO2–Al2O3–P2O5–K2O–CaO–F? (SAF) based glass-ceramic was used as outer bioactive layer. The deposition of the intermediate SCP layer was necessary in order to obtain a good adhesion of the

  8. Optical absorption and photoluminescence properties of Er 3+ doped mixed alkali borate glasses

    Microsoft Academic Search

    Y. C. Ratnakaram; A. Vijaya Kumar; D. Tirupathi Naidu; J. L. Rao

    2005-01-01

    An investigations of the optical absorption and fluorescence spectra of 0.2mol% Er2O3 in mixed alkali borate glasses of the type 67.8B2O3·xLi2O(32?x)Na2O, 67.8B2O3·xLi2O(32?x)K2O and 67.8B2O3·xNa2O(32?x)K2O (where x = 8, 12, 16, 20 and 24) are presented. The glasses were obtained by quenching melts consisting of H3BO3, Li2CO3, Na2CO3, K2CO3 and Er2O3 (950–1100°C, 1.5–2h) between two brass plates. Spectroscopic parameters like Racah

  9. Major Element Geochemistry of Biofilms in a Silica-Precipitating Hot Spring

    NASA Astrophysics Data System (ADS)

    Havig, J. R.; Shock, E. L.; Moore, G.

    2007-12-01

    Hydrothermal biofilm communities represent one of the best present-day representations of early microbial communities, dating back to 2.5 Ga, and possibly 3.8 Ga in the geologic record. Silica-precipitating hydrothermal springs have been thought to have great potential for biosignature preservation. The interactions of hydrothermal water, biofilms, and precipitated siliceous sinter, however, remain poorly constrained. To this end, we collected water and biofilm, as well as contextual sinter and rock samples from various hot springs in Yellowstone National Park. Here we focus on one hot spring in Sentinel Meadow (Lower Geyser Basin), with temperature and pH that vary from the source (93 C, pH 7.4) to the farthest of five collection points down channel (56 C, pH 8.2). Elemental analysis reveals that the biofilms are made up of from <1 to ~11 % dry wt. carbon and ~0.1 to 1% dry wt. nitrogen. Major element analysis via electron microprobe and complimentary x-ray fluorescence show that (excluding C and N from the total) SiO2 constitutes 86 to 94 % dry weight mass, with the rest made up of Al2O3 (3 to 8%), Na2O (1.7 to 3.7%), K2O (0.6 to 1.5%), and minor amounts of FeO, CaO, MgO, and TiO2 (<1%). Local sinter is SiO2 (97.5% dry wt.), Na2O (1.5%), and <1% Al2O3, FeO, K2O, CaO, MgO, and TiO2. In addition, sinter contains measurable amounts of carbon (1.4%) and nitrogen (0.2%). Discrepancies between the biofilm and sinter values show that the geochemical compositions of biofilms are not captured by the precipitating silica. If biofilms accumulated elements strictly from the water, then it would take as much as 440 L of water to supply 1 gram (dry wt) of biofilm with the elements contained therein, assuming complete uptake. This seems especially unlikely in the case of Al, which is quite dilute (~500 ppb), poses very little benefit nutritionally, and increases in concentration down channel. Other major element components also exhibit at least one, if not all, of these traits. A potential source of the elements found in biofilms is aeolian-deposited dust. Area country rock is dominated by siliceous volcanism, represented locally by rhyolite samples collected from Sentinel Meadow. With an average value of ~10 wt % Al2O3 for the surrounding country rock, it would take approximately 0.6 grams of the ground up rock as dust to account for the Al found in one gram of biofilm. The low Al2O3 content of the sinter indicates that the Al is not entombed from the biofilms. A hypothesis for the above discrepancies in Al (as well as other elements) is that dust deposited in the water is captured on the biofilm surfaces, and the biofilm community then breaks down the dust, utilizing any nutritionally or metabolically important elements, and either precipitating (for Si) or releasing (for Al) unnecessary elements.

  10. Growth of Megaspherulites In a Rhyolitic Vitrophyre

    NASA Technical Reports Server (NTRS)

    Smith, Robert K.; Tremallo, Robin L.; Lofgren, Gary E.

    2000-01-01

    Megaspherulites occur in the middle zone of a thick sequence of rhyolitic vitrophyre that occupies a small, late Eocene to early Oligocene volcanic-tectonic basin near Silver Cliff, Custer County, Colorado. Diameters of the megaspherulites range from 0.3 m to over 3.66 m, including a clay envelope. The megaspherulites are compound spherulites. consisting of an extremely large number (3.8 x 10(exp 9) to 9.9 x 10(exp 9)) of individual growth cones averaging 3 mm long by 1.25 mm wide at their termination. They are holocrystalline, very fine- to fine-grained, composed of disordered to ordered sanidine (orthoclase) and quartz, and surrounded by a thin K-feldspar, quartz rich rind, an inner clay layer with mordenite, and an outer clay layer composed wholly of 15 A montmorillonite. Whole rock analyses of the megaspherulites show a restricted composition from their core to their outer edge, with an average analyses of 76.3% SiO2, 0.34% CaO, 2.17% Na2O, 6.92% K2O, 0.83% H2O+ compared to the rhyolitic vitrophyre from which they crystallize with 71.07% SiO2, 0.57% CaO, 4.06% Na2O,4.l0% K2O, and 6.40% H2O+. The remaining oxides of Fe2O3 (total Fe), A12O3, MnO,MgO, TiO2, P2O5, Cr2O3, and trace elements show uniform distribution between the megaspherulites and the rhyolitic vitrophyre. Megaspherulite crystallization began soon after the rhyolitic lava ceased to flow as the result of sparse heterogeneous nucleation, under nonequilibrium conditions, due to a high degree of undercooling, delta T. The crystals grow with a fibrous habit which is favored by a large delta T ranging between 245 C and 295 C, despite lowered viscosity, and enhanced diffusion due to the high H2O content, ranging between 5% and 7%. Therefore, megaspherulite growth proceeded in a diffusion controlled manner, where the diffusion, rate lags behind the crystal growth rate at the crystal-liquid interface, restricting fibril lengths and diameters to the 10 micron to 15 micron and 3 micron and 8 micron ranges respectively. Once diffusion reestablishes itself at the crystallization front, a new nucleation event occurs at the terminated tips of the fibril cones and a new cone begins to develop with a similar orientation (small angle branching) to the earlier cones. During crystallization, these fibril cones impinge upon each other, resulting in fibril cone-free areas. These cone-free areas consist of coarser, fine-grained phases, dominated by quartz, which crystallized from the melt as it accumulated between the crystallizing K-feldspar fibrils of the cones. The anhydrous nature of the disordered to ordered sanidine (orthoclase) and quartz, suggests that water in the vitrophyre moved ahead of the crystallization front, resulting in a water rich fluid being enriched in Si, K, Na, Mg, Ca, Sr, Ba, and Y. The clay layers associated with the megaspherulites are therefore, the result of the deuteric alteration between the fractionated water and the vitrophyre, as indicated by the presence of the minerals mordenite and montmorillonite. This silica rich fluid also resulted in the total silicification of the megaspherulites within the upper 3 m of the vitrophyre.

  11. Petrography and Geochemistry of the Zamora Batholith in the south of the sub-Andean zone (Ecuador)

    NASA Astrophysics Data System (ADS)

    Villares, F. M.

    2013-05-01

    The Zamora Batholith is an intrusive complex that is located in the extreme south-east of Ecuador. It has dimensions of 200 x 50 km approximately. It is mainly located in the Zamora Chinchipe province from which it takes its name. This study consisted in the petrographic and geochemical characterization of the Zamora Batholith in the area covered by 1: 50,000 geological maps of Centro Shaime, Guayzimi, Paquisha, Los Encuentros and El Pangui. Fieldwork was done by the "Proyecto Mapeo Geológico escala 1:50.000 (zonas prospectivas mineras)" of the Instituto Nacional de Investigación Geológico, Minero, Metalúrgico of Ecuador. This research was performed with 59 thin sections and 10 whole - rock chemical analysis done in the C.I.C of the Granada University. The Zamora Batholith intrudes Triassic to Jurassic volcanic rocks. It is overlaid by sandstones of the Hollin Formation of the Upper Aptian age and shale and limestone from the Napo Formation. Post-cretaceous deposits of ash and lava flows of andesitic to rhyolitic compositions cover the batholith. The petrography of the Zamora Batholith ranges from tonalite to monzogranite with the same qualitative mineralogy. The rocks are composed by different proportions of plagioclase, amphibole, feldspar K, quartz, biotite, opaque, pyroxene and epidote, as accessory minerals has zircon, sphene and apatite. To the south of the Conguime and Guayzimi towns, the dominant petrography is medium to coarse grained amphibole granodiorite with tonalitic and monzogranitic subordinates. To the north monzogranites are dominant rocks and subordinate granodiorites. To the East of Santa Elena the sienogranites are associated with El Hito porphyritic granite that intrudes to Zamora Batholith. Frequently the batholith has propylitic alteration; which produces a primary association of chlorite, epidote, calcite and pyrite. The granitoids have dioritic to granitic compositions (60.09 to 73.6 wt.% SiO2) and are I - type, medium to high-K calc-alkaline. They have affinities slightly peraluminous (ASI = 1,00 to 1,16). CaO is moderate to high (CaO ? 3.58), the alkalis have averaged of Na2O?3,09 and K2O?3,28. The concentrations of Na2O/K2O are moderate ranging between 0.7 and 1.7, with an average value of 1.04. The contents of Ba and Sr are moderate. The content of Zr is low (61 to 161 ppm). The multi-element diagrams normalized to chondritic values and to primitive mantle show Nb and Ta negative anomaly. Considering the multi-element diagrams, the rocks are slightly enriched in LILE (Large Ion-Lithophile-elements) mainly in Rb, Cs and Ba and slight positive anomalies in K and Sr, other incompatible elements have negative anomalies such as HFSE ( High Field Strength Elements) Ti, Nb, Ta. The values of (Eu/Eu*)N are in the range of 0.54 to 1.03. (Eu* = (SmN*GdN)1/2). Correlations between major element and silica, and relationships between trace elements indicate that fractional crystallization is a dominant process in the magma evolution. Most granitoids are also slightly peraluminous; but we believe this characteristic is due to rock alteration. The Zamora Batolith is a plutonic complex generated within a magmatic arc in normal conditions of maturity.

  12. Geochemistry and petrogenesis of Mashhad granitoids: An insight into the geodynamic history of the Paleo-Tethys in northeast of Iran

    NASA Astrophysics Data System (ADS)

    Mirnejad, H.; Lalonde, A. E.; Obeid, M.; Hassanzadeh, J.

    2013-06-01

    Mashhad granitoids in northeast Iran are part of the so-called Silk Road arc that extended for 8300 km along the entire southern margin of Eurasia from North China to Europe and formed as the result of a north-dipping subduction of the Paleo-Tethys. The exact timing of the final coalescence of the Iran and Turan plates in the Silk Road arc is poorly constrained and thus the study of the Mashhad granitoids provides valuable information on the geodynamic history of the Paleo-Tethys. Three distinct granitoid suites are developed in space and time (ca. 217-200 Ma) during evolution of the Paleo-Tethys in the Mashhad area. They are: 1) the quartz diorite-tonalite-granodiorite, 2) the granodiorite, and 3) the monzogranite. Quartz diorite-tonalite-granodiorite stock from Dehnow-Vakilabad (217 ± 4-215 ± 4 Ma) intruded the pre-Late Triassic metamorphosed rocks. Large granodiorite and monzogranite intrusions, comprising the Mashhad batholith, were emplaced at 212 ± 5.2 Ma and 199.8 ± 3.7 Ma, respectively. The high initial 87Sr/86Sr ratios (0.708042-0.708368), low initial 143Nd/144Nd ratios (0.512044-0.51078) and low ?Nd(t) values (- 5.5 to - 6.1) of quartz diorite-tonalite-granodiorite stock along with its metaluminous to mildly peraluminous character (Al2O3/(CaO + Na2O + K2O) Mol. = 0.94-1.15) is consistent with geochemical features of I-type granitoid magma. This magma was derived from a mafic mantle source that was enriched by subducted slab materials. The granodiorite suite has low contents of Y (? 18 ppm) and heavy REE (HREE) (Yb < 1.53 ppm) and high contents of Sr (> 594 ppm) and high ratio of Sr/Y (> 35) that resemble geochemical characteristics of adakite intrusions. The metaluminous to mildly peraluminous nature of granodiorite from Mashhad batholiths as well as its initial 87Sr/86Sr ratios (0.705469-0.706356), initial 143Nd/144Nd ratios (0.512204-0.512225) and ?Nd(t) values (- 2.7 to - 3.2) are typical of adakitic magmas generated by partial melting of a subducted slab. These magmas were then hybridized in the mantle wedge with peridotite melt. The quartz diorite-tonalite-granodiorite stock and granodiorite batholith could be considered as arc-related granitoid intrusions, which were emplaced during the northward subduction of Paleo-Tethys Ocean crust beneath the Turan micro-continent. The monzogranite is strongly peraluminous (Al2O3/(CaO + Na2O + K2O) Mol. = 1.07-1.17), alkali-rich with normative corundum ranging between 1.19% and 2.37%, has high initial 87Sr/86Sr ratios (0.707457-0.709710) and low initial 143Nd/144Nd ratios (0.512042-0.512111) and ?Nd(t) values (- 5.3 to - 6.6) that substantiate with geochemical attributes of S-type granites formed by dehydration-melting of heterogeneous metasedimentary assemblages in thickened lower continental crust. The monzogranite was emplaced as a consequence of high-temperature metamorphism during the final integration of Turan and Iran plates. The ages found in the Mashhad granites show that the subduction of Paleo-Tethys under the Turan plate that led to the generation of arc-related Mashhad granites in late-Triassic, finally ceased due to the collision of Iran and Turan micro-plates in early Jurassic.

  13. Chemical zonation in olivine-hosted melt inclusions

    NASA Astrophysics Data System (ADS)

    Newcombe, M. E.; Fabbrizio, A.; Zhang, Youxue; Ma, C.; Le Voyer, M.; Guan, Y.; Eiler, J. M.; Saal, A. E.; Stolper, E. M.

    2014-07-01

    Significant zonation in major, minor, trace, and volatile elements has been documented in naturally glassy olivine-hosted melt inclusions from the Siqueiros Fracture Zone and the Galapagos Islands. Components with a higher concentration in the host olivine than in the melt (e.g., MgO, FeO, Cr2O3, and MnO) are depleted at the edges of the zoned melt inclusions relative to their centers, whereas except for CaO, H2O, and F, components with a lower concentration in the host olivine than in the melt (e.g., Al2O3, SiO2, Na2O, K2O, TiO2, S, and Cl) are enriched near the melt inclusion edges. This zonation is due to formation of an olivine-depleted boundary layer in the adjacent melt in response to cooling and crystallization of olivine on the walls of the melt inclusions, concurrent with diffusive propagation of the boundary layer toward the inclusion center. Concentration profiles of some components in the melt inclusions exhibit multicomponent diffusion effects such as uphill diffusion (CaO, FeO) or slowing of the diffusion of typically rapidly diffusing components (Na2O, K2O) by coupling to slow diffusing components such as SiO2 and Al2O3. Concentrations of H2O and F decrease toward the edges of some of the Siqueiros melt inclusions, suggesting either that these components have been lost from the inclusions into the host olivine late in their cooling histories and/or that these components are exhibiting multicomponent diffusion effects. A model has been developed of the time-dependent evolution of MgO concentration profiles in melt inclusions due to simultaneous depletion of MgO at the inclusion walls due to olivine growth and diffusion of MgO in the melt inclusions in response to this depletion. Observed concentration profiles were fit to this model to constrain their thermal histories. Cooling rates determined by a single-stage linear cooling model are 150-13,000 °C h-1 from the liquidus down to ~1,000 °C, consistent with previously determined cooling rates for basaltic glasses; compositional trends with melt inclusion size observed in the Siqueiros melt inclusions are described well by this simple single-stage linear cooling model. Despite the overall success of the modeling of MgO concentration profiles using a single-stage cooling history, MgO concentration profiles in some melt inclusions are better fit by a two-stage cooling history with a slower-cooling first stage followed by a faster-cooling second stage; the inferred total duration of cooling from the liquidus down to ~1,000 °C ranges from 40 s to just over 1 h. Based on our observations and models, compositions of zoned melt inclusions (even if measured at the centers of the inclusions) will typically have been diffusively fractionated relative to the initially trapped melt; for such inclusions, the initial composition cannot be simply reconstructed based on olivine-addition calculations, so caution should be exercised in application of such reconstructions to correct for post-entrapment crystallization of olivine on inclusion walls. Off-center analyses of a melt inclusion can also give results significantly fractionated relative to simple olivine crystallization. All melt inclusions from the Siqueiros and Galapagos sample suites exhibit zoning profiles, and this feature may be nearly universal in glassy, olivine-hosted inclusions. If so, zoning profiles in melt inclusions could be widely useful to constrain late-stage syneruptive processes and as natural diffusion experiments.

  14. The Tonalite-Trondhjemite-Granodiorite (TTG) to Calc-alkaline Granodiorite-Granite Transition: Evolution of the Archaean Basement of the Quadrilátero Ferrífero Province (Southeast Brazil)

    NASA Astrophysics Data System (ADS)

    Farina, F.; Albert, C.; Lana, C.; Stevens, G.

    2014-12-01

    The Bação, Bonfim and Belo Horizonte domes are the largest domes in the Archaean Southern São Francisco craton (Quadrilátero Ferrífero, Brazil). These domes are mainly formed by fine-grained banded gneisses typically intruded by leucogranitic veins and by weakly foliated granites, cropping out as large batholiths and small scale-domains closely associated to the gneisses. Granites and gneisses have high silica content (70-76 wt%), K2O ranging from 2wt% to 6wt%, Sr from 600 to 40 ppm and La/Yb from 150 to 5. Based on their K2O/Na2O ratios, these rocks are subdivided in three groups: sodic (K2O/Na2O?0.7), transitional (0.7<K2O/Na2O<1.1) and potassic (K2O/Na2O?1.1). There is no direct relationship between the metamorphic overprint (granites vs. gneisses) and the K2O/Na2O ratio; e.g. granites plots equally in the sodic and potassic groups. Overall, the composition of gneisses and granitoids in the three domes marks the transition between Archean TTGs and modern calc-alkalic granitoids. LA-ICP-MS zircon U-Pb data allow three main periods of magmatism to be defined. The oldest recorded magmatic contribution to the craton began at 3200 Ma, as attested by the occurrence of inherited zircons in younger granitoids as well as by the fact that zircons with a ca. 3200 Ma age represent a significant subset in the detrital zircon population of the greenstone belt. Subsequent magmatic events took place at 2930-2870 Ma and 2780-2700 Ma. The geochronological data reveal that, although the sodic rocks represent a greater proportion of the older gneisses, sodic, transitional and potassic granitoids intruded contemporaneously. The geochemistry of sodic and transitional granites and gneisses suggests that they formed by partial melting of TTG source rocks that are not preserved in the rock record. MC-ICP-MS Hf isotope data on magmatic zircon, suggesting crustal reworking with minor or no involvement of juvenile magmas, support this interpretation. Further recycling of sodic-transitional gneisses does not account for the genesis of potassic granitoids whose origin requires the participation of magmas derived by metasedimentary source rocks.

  15. Characterization and Origin of Aluminous A-type Granites from the Lachlan Fold Belt, Southeastern Australia

    Microsoft Academic Search

    P. L. KING; A. J. R. WHITE; B. W. CHAPPELL; C. M. ALLEN

    1997-01-01

    The term ‘A-type’ was proposed in an abstract by A-type granites, such as those of the Lachlan Fold Belt, should be Loiselle & Wones (1979) to distinguish ‘mildly alkaline’ defined as ‘aluminous A-type’ granites and should not be grouped rocks (high K2O + Na2O) from typical ‘calc-alkaline’ (I- with peralkaline granites. The Lachlan Fold Belt aluminous type) rocks. Other distinctive

  16. Bioactive borate glass scaffolds: in vitro and in vivo evaluation for use as a drug delivery system in the treatment of bone infection

    Microsoft Academic Search

    Xin Liu; Zongping Xie; Changqing Zhang; Haobo Pan; Mohamed N. Rahaman; Xin Zhang; Qiang Fu; Wenhai Huang

    2010-01-01

    The objective of this work was to evaluate borate bioactive glass scaffolds (with a composition in the system Na2O–K2O–MgO–CaO–B2O3–P2O5) as devices for the release of the drug Vancomycin in the treatment of bone infection. A solution of ammonium phosphate,\\u000a with or without dissolved Vancomycin, was used to bond borate glass particles into the shape of pellets. The in vitro degradation

  17. Synthesis, Ion-exchange, Structural Characterization and Adsorption of K, Na-FER Type Zeolite

    Microsoft Academic Search

    Yingcai Long; Minghua Ma; Yaojun Sun; Huiwen Jiang

    2000-01-01

    Synthesis of K, Na -FER type zeolite wasstudied in the reactant system ofK 2O-–Na 2O-–Al 2O 3-–SiO 2-–CO 3-–HCO 3-ndash;H 2O.Sodium silicate, silica sol andfumed silica were tested as the silica source, andsolid aluminum sulfate, aluminum hydroxide andmeta-kaolinite as the alumina source. The startingmaterials, the composition of the reactant, and thesynthesis temperature greatly influence the phasescrystallized. A pure phase of

  18. By-Products Utilization

    E-print Network

    Wisconsin-Milwaukee, University of

    .5 -- -- -- Potassium Oxide, K2O 3.1 3.4 -- -- -- Sodium Oxide, Na2O 1.4 3.3 -- -- -- Sulfate, SO3 4.3 13.0 4.0, Max. 5 Class F Silicon Dioxide, SiO2 35.0 16.9 -- -- -- Aluminum Oxide, Al2O3 15.0 10.2 -- -- -- Iron Oxide, Fe samples unless noted otherwise) Element Material Biron #4 Biron #5 Aluminum (Al) 67543.8

  19. Synthèse, structure cristalline, conductivité ionique, et propriétés magnétiques d'un nouveau ferrite de type alumine beta'' Na1.3K0.6Fe10.1Zn0.9O17

    Microsoft Academic Search

    H. Vincent; A. Bekka; M. Anne; J. C. Joubert

    1989-01-01

    A new type of rhombohedral beta'' alumina-like ferrite, its platelet-shaped single crystals up to 5 × 5 mm in size, has been synthesized using a flux method (37% Na2O, 63% Fe2O3 molar ratio) at 1300°C. Small amounts of bivalent oxides MeO (Me = Mg, Cu, Zn) were added to the initial K2O . Fe2O3 powder mixture to stabilize the beta''

  20. The geology and geochronology of the Annandagstoppane granite, Western Dronning Maud Land, Antarctica

    Microsoft Academic Search

    J. M. Barton; R. Klemd; H. L. Allsopp; S. H. Auret; Y. E. Copperthwaite

    1987-01-01

    The Annandagstoppane Granite is exposed at three nunataks in Western Dronning Maud Land, Antarctica. It comprises medium- to coarse-grained granite crosscut by veins of pegmatite and graphic granite and has many S-type characteristics such as containing normative corundum greater than 1.1%, molecular Al2O3\\/(CaO+K2O+Na2O) greater than 1.1 and very little zircon. Hydrothermal alteration in the Granite is variably developed and has

  1. Petrochemical variations among mildly peralkaline (comendite) obsidians from the oceans and continents

    Microsoft Academic Search

    D. K. Bailey; R. MacDonald

    1970-01-01

    Eleven new analyses and modes of comendite obsidians are presented, and compared with all available data on similar rocks. Most specimens are aphyric or contain only sparse phenocrysts, most commonly alkali feldspar. The oxides SiO2, Al2O3, Na2O and K2O total over ninety percent by weight in all analyses. Iron, as FeO, is the only other constituent rising above one percent

  2. Dilatometeric study of shrinkage during sintering process for porcelain stoneware body in presence of nepheline syenite

    Microsoft Academic Search

    A. Salem; S. H. Jazayeri; E. Rastelli; G. Timellini

    2009-01-01

    The shrinkage of porcelain stoneware body containing different values of nepheline syenite was investigated. Dilatomeric tests were carried out on suitable specimens to obtain the expansion-shrinkage behavior of ceramic bodies. The differences found in shrinkage data were evaluated by kinetic model and determination of activation energy. The results showed that the activation energy increases with Na2O+K2O\\/quartz ratio and reaches to

  3. Method of preventing oxidation of graphite fireproof material

    NASA Technical Reports Server (NTRS)

    Yamauchi, S.; Suzuki, H.

    1981-01-01

    A method of preventing oxidation of graphite fireproof material is given. A blend of 1 to 33 weight parts alumina and 3 to 19 parts of K2O + Na2O in 100 parts of SiO2 is pulverized followed by addition of 5 to 160 parts of silicon carbide powder in 100 parts of the mixture. This is thoroughly blended and coated on the surface of graphite fireproof material.

  4. The Behavior of Pyroxenes During Partial Melting of Pyroxenite and Lherzolite in the Mantle: An Experimental and Numerical Study

    NASA Astrophysics Data System (ADS)

    Lo Cascio, M.; Liang, Y.

    2004-12-01

    Pyroxenes are the primary phases involved in partial melting of peridotite and pyroxenite lithologies in the upper mantle. In order to better understand the grain-scale processes of pyroxene melting and their effects on major and trace element distributions during magma generation, we carried out a series of kinetic melting experiments using reaction couple method. Partial melting experiments were conducted at 1340° C and 1.5 GPa for 72 hrs using reaction couples formed by juxtaposing pre-synthesized rods of orthopyroxenite (90% opx, 5% olivine, 5% melt) against clinopyroxenite (90% cpx + 10% melt). These laboratory experiments were supplemented by numerical simulations of partial melting in binary and ternary systems. Reaction between orthopyroxenite and clinopyroxenite at 1340° C and 1.5GPa results in a reactive boundary layer (RBL, 240 ? m after 72 hrs) that consists of euhedral olivine (35%), cpx (45%), and melt (20%). The RBL is located on the orthopyroxenite side of the original interface. The grain sizes of ol and cpx in the RBL are significantly larger than those in the orthopyroxenite and the clinopyroxenite. Clinopyroxene compositions vary systematically across the RBL, for example the Na2O and TiO2 content decrease from 1.05% and 0.35%, respectively, in the clinopyroxenite to 0.83% and 0.14% at the orthopyroxenite-RBL interface. The melt is concentrated in the RBL and appears to localize in those areas where olivine grains are more densely accumulated. The average melt in the RBL is a ne-normative alkali basalt (10.6% MgO, 49.2% SiO2, 4.7% Na2O, 0.28% K2O) and has relatively high Al2O3 (15.5%) and CaO (10.7%). The characteristics of increasing grain size and varying cpx and melt compositions in the RBL are very similar to those observed in our clinopyroxenite-harzburgite partial melting experiments [1], consistent with the grain-scale melting processes that involve dissolution of opx at the orthopyroxenite-RBL interface, precipitation of ol and new cpx within the RBL, and production of Na2O-Al2O3-SiO2-rich melts in that region. This dissolution and reprecipitation process, due to two very different time-scales of crystal-melt interaction in partially molten systems, is reproduced in our numerical simulations of partial melting of bio-mineralic rocks in binary and ternary systems, and is likely to occur during lherzolite and pyroxenite partial melting in the laboratory and nature. One of the important consequences of cpx reprecipitation during peridotite and pyroxenite partial melting is the significant reduction in diffusive reequilibration time between the cpx and the surrounding melt, since diffusion coefficients of trace elements such as REE, U, and Th in cpx are much smaller than those of major elements in cpx and melt. The rate of cpx reprecipitation is dominated by the rate of chemical diffusion of the major components in cpx. This dissolution and reprecipitation process may help to explain the apparent equilibrium melting trends observed in some slab derived magmas that were produced at relatively low temperatures. The mechanisms outlined above can also be used to better understand the melting process of lherzolite and pyroxene-rich lithologies in the upper mantle and could partially explain the petrogenesis of high Na2O-Al2O3-SiO2 magmas, without the involvement of an eclogite component in the source region. [1] Lo Cascio et al., GRL, 31, L16605, doi: 10.1029/2004GL020602

  5. Partial melting of apatite-bearing charnockite, granulite, and diorite: Melt compositions, restite mineralogy, and petrologic implications

    NASA Technical Reports Server (NTRS)

    Beard, James S.; Lofgren, Gary E.; Sinha, A. Krishna; Tollo, Richard P.

    1994-01-01

    Melting experiments (P = 6.9 kbar, T = 850-950 deg C, NNO is less than fO2 is less than HM) were done on mafic to felsic charnockites, a dioritic gneiss, and a felsic garnet granulite, all common rock types in the Grenville basement of eastern North America. A graphite-bearing granulite gneiss did not melt. Water (H2O(+) = 0.60 to 2.0 wt %) is bound in low-grade, retrograde metamorphic minerals and is consumed during the earliest stages of melting. Most melts are water-undersaturated. Melt compositions range from metaluminous, silicic granodiorite (diorite starting composition) to peraluminous or weakly metaluminous granites (all others). In general, liquids become more feldspathic, less silicic, and less peraluminous and are enriched in FeO, MgO, and TiO2 with increasing temperature. Residual feldspar mineralogy controls the CaO, K2O, and Na2O contents of the partial melts and the behavior of these elements can be used, particularly if the degree of source melting can be ascertained, to infer some aspects of the feldspar mineralogy of the source. K-feldspar, a common restite phase in the charnockite and granulite (but not the diorite) should control the behavior of Ba and, possibly, Eu in these systems and yield signatures of these elements that can distinguish source regions and, in some cases, bulk versus melt assimilation. Apatite, a common restite phase, is enriched in rare earth elements (REE), especially middle REE. Retention of apatite in the restite will result in steep, light REE-enriched patterns for melts derived from the diorite and charnockites.

  6. Constraints on abundance, composition, and nature of X-ray amorphous components of soils and rocks at Gale crater, Mars

    NASA Astrophysics Data System (ADS)

    Dehouck, Erwin; McLennan, Scott M.; Meslin, Pierre-Yves; Cousin, Agnès.

    2014-12-01

    X-ray diffraction patterns of the three samples analyzed by Curiosity's Chemistry and Mineralogy (CheMin) instrument during the first year of the Mars Science Laboratory mission—the Rocknest sand, and the John Klein and Cumberland drill fines, both extracted from the Sheepbed mudstone—show evidence for a significant amorphous component of unclear origin. We developed a mass balance calculation program that determines the range of possible chemical compositions of the crystalline and amorphous components of these samples within the uncertainties of mineral abundances derived from CheMin data. In turn, the chemistry constrains the minimum abundance of amorphous component required to have realistic compositions (all oxides ? 0 wt %): 21-22 wt % for Rocknest and 15-20 wt % for Cumberland, in good agreement with estimates derived from the diffraction patterns (~27 and ~31 wt %, respectively). Despite obvious differences between the Rocknest sand and the Sheepbed mudstone, the amorphous components of the two sites are chemically very similar, having comparable concentrations of SiO2, TiO2, Al2O3, Cr2O3, FeOT, CaO, Na2O, K2O, and P2O5. MgO tends to be lower in Rocknest, although it may also be comparable between the two samples depending on the exact composition of the smectite in Sheepbed. The only unambiguous difference is the SO3 content, which is always higher in Rocknest. The observed similarity suggests that the two amorphous components share a common origin or formation process. The individual phases possibly present within the amorphous components include: volcanic (or impact) glass, hisingerite (or silica + ferrihydrite), amorphous sulfates (or adsorbed SO42-), and nanophase ferric oxides.

  7. Paleoenvironmental History of the Retezat Mountains (Southern Carpathians) Inferred from Geochemical Data

    NASA Astrophysics Data System (ADS)

    Hubay, Katalin; Braun, Mihály; Harangi, Sándor; Magyari, Enik?

    2014-05-01

    This study applied lake sediment geochemistry to reconstruct climate changes in the Southern Carpathians within the frame of PROLONG (Providing long environmental records of Late Quaternary climatic oscillations in the Retezat Mountains) project. The main aim of this project is to reconstruct the changes during the Lateglacial and the Early Holocene period in the Retezat Mountains, Southern Carpathians. After retreat of the last major glaciers numerous glacial lakes leaving behind with sediments dating back to ca. 16,000 cal. yr BP. In 2007 and 2008 continuous undisturbed sediment cores were obtained from four glacial lakes (Brazi, Gales, Lia, Bukura) in the Retezat Mts. (Southern Carpathians, Romania) with Livingstone and modified Kullenberg corers. Two of the studied lakes are located on the southern slope (Bukura, Lia) of the mountain, while the Brazi and Gales are situated on the northern slope. After the drillings, the sediment cores were sliced into 1 cm wide subsamples. High-resolution geochemical analysis was done to study soil development an in-lake processes in response to high-frequency and high-amplitude climatic changes within the Lateglacial and Early Holocene. Loss-on-ignition was used to determining the sediment organic matter content. Total element concentrations were measured using an Inductive Coupled Plasma Optical Emission Spectrometer (ICP-OES) and Microwave Plasma Atomic Emission Spectrometer (MP-AES). Concentration of major elements by means of bulk analysis were determined and calculated in oxide forms (Al2O3, SiO2, TiO2, CaO, MgO, K2O, Na2O, Fe2O3, MnO, SO3). Multivariate statistical analyses (PCA, LDA) and cluster analysis were performed on geochemical records. The sediments deposited during the cold and warm period of Lateglacial and Early Holocene showed significantly different chemical compositions. The results indicate that the detailed geochemical analysis on the sediment has the potential to reflect past climatic conditions.

  8. Thermal Expansion Calculation of Silicate Glasses at 210°C, Based on the Systematic Analysis of Global Databases

    SciTech Connect

    Fluegel, Alex

    2010-10-01

    Thermal expansion data for more than 5500 compositions of silicate glasses were analyzed statistically. These data were gathered from the scientific literature, summarized in SciGlass© 6.5, a new version of the well known glass property database and information system. The analysis resulted in a data reduction from 5500 glasses to a core of 900, where the majority of the published values is located within commercial glass composition ranges and obtained over the temperature range 20 to 500°C. A multiple regression model for the linear thermal expansivity at 210°C, including error formula and detailed application limits, was developed based on those 900 core data from over 100 publications. The accuracy of the model predictions is improved about twice compared to previous work because systematic errors from certain laboratories were investigated and corrected. The standard model error (precision) was 0.37 ppm/K, with R² = 0.985. The 95% confidence interval for individual predictions largely depends on the glass composition of interest and the composition uncertainty. The model is valid for commercial silicate glasses containing Na2O, CaO, Al2O3, K2O, MgO, B2O3, Li2O, BaO, ZrO2, TiO2, ZnO, PbO, SrO, Fe2O3, CeO2, fining agents, and coloring and de-coloring components. In addition, a special model for ultra-low expansion glasses in the system SiO2-TiO2 is presented. The calculations allow optimizing the time-temperature cooling schedule of glassware, the development of glass sealing materials, and the design of specialty glass products that are exposed to varying temperatures.

  9. (210)Pb and composition data of near-surface sediments and interstitial waters evidencing anthropogenic inputs in Amazon River mouth, Macapá, Brazil.

    PubMed

    Nery, José Reinaldo Cardoso; Bonotto, Daniel Marcos

    2011-04-01

    Activity profiles of excess (210)Pb determined in three sediment cores from Amazon River mouth, Macapá city, Brazil, provided the evaluation of sedimentation rates, contributing to a better knowledge of the hydrological conditions in the site that is the capital of Amapá State and is drained by the waters of the huge Amazon River. Chemical data were also determined in the sediments, allowing identify signatures coupled to anthropogenic inputs held in the past in Amapá State. Significant direct relationships between LOI (loss on ignition) and organic matter were found for all sediments profiles. Silica was found to be inversely related to organic matter in the three profiles; its decrease accompanied an increase on the specific surface of the sediments. This relationship was confirmed by a great number of inverse significant correlations among silica and oxides Na(2)O, K(2)O, CaO, MgO, Al(2)O(3), P(2)O(5), Fe(2)O(3) and MnO. It was possible to identify the role of organic matter on adsorption of several oxides in the core sediments profiles. Apparent sediment mass accumulation rates corresponding to values between 450 and 2510 mg cm(-2)yr(-1) were obtained, and are compatible with the results of others studies. The (210)Pb activities in one sampling point suggested the occurrence of anthropogenic inputs related to the initial period of the mining activities conducted in Serra do Navio, Amapá State, for the commercialization of Mn ores. This was reinforced by the abrupt fluctuations in chemical data obtained for the sediments and composition of the interstitial waters occurring there. The Atlantic hurricane activity also appeared to affect the sedimentation rates in the area, as two different values were recorded in each profile. PMID:21353731

  10. Oriented bioactive glass (13-93) scaffolds with controllable pore size by unidirectional freezing of camphene-based suspensions: microstructure and mechanical response

    PubMed Central

    Liu, Xin; Rahaman, Mohamed N.; Fu, Qiang

    2010-01-01

    Scaffolds of 13-93 bioactive glass (composition 6Na2O, 8K2O, 8MgO, 22CaO, 2P2O5, 54SiO2; mol %), containing oriented pores with controllable diameter, were prepared by unidirectional freezing of camphene-based suspensions (10 vol% particles) on a cold substrate (?196°C or 3°C). By varying the annealing time (0–72 h) to coarsen the camphene phase, constructs with the same porosity (86 ± 1%) but with controllable pore diameters (15–160 ?m) were obtained after sublimation of the camphene. The pore diameters had a self-similar distribution that could be fitted by a diffusion-controlled coalescence model. Sintering (1 h at 690°C) was accompanied by a decrease in the porosity and pore diameter, the magnitude of which depended on the pore size of the green constructs, giving scaffolds with a porosity of 20–60% and average pore diameter of 6–120 ?m. The compressive stress vs. deformation response of the sintered scaffolds in the orientation direction was linear, followed by failure. The compressive strength and elastic modulus in the orientation direction varied from 180 MPa and 25 GPa, respectively, (porosity = 20%) to 16 MPa and 4 GPa, respectively, (porosity = 60%), which were 2–3 times larger than the values in the direction perpendicular to the orientation. The potential use of these 13-93 bioactive glass scaffolds for the repair of large defects in load-bearing bones, such as segmental defects in long bones, is discussed. PMID:20807594

  11. Chemical composition of phosphorites of the Phosphoria Formation

    USGS Publications Warehouse

    Gulbrandsen, R.A.

    1966-01-01

    The chemical composition, both major and minor constituents, of 60 samples of phosphorite from the Phosphoria Formation was determined. Major constituents of the average phosphorite are, by weight per cent: SiO2, 11??9; Al2O3, 1??7; Fe2O3,1??1; MgO, 0??3; CaO, 44??0; Na2O, 0??6; K2O, 0??5; total H2O, 2??2; H2O-, 0??6; TiO2, 0??1; P2O5, 30??5; CO2, 2??2; SO3, 1??8; F, 3??1; organic matter, 2??1; and oil, 0??2. Uranium averages 0??009 per cent. The phosphate mineral is basically apatite, Ca5(PO4)3F, with small but significant and variable substitutions-Na, Sr, U and Th for Ca, and CO3 and SO4 for PO4. Rare metals not associated with apatite are associated principally with the organic-matter component of the rocks. This group includes As, Ag, Cd, Cr, Cu, Mo, Ni, Sb, Se, V and Zn. Chromium is the most abundant, having a modal abundance of 0??1 per cent and a maximum concentration of 0??3 per cent. The average phosphorite is composed of approximately 80 per cent apatite, 10 per cent quartz, 5 per cent muscovite-illite, 2 per cent organic matter, 1 per cent dolomite-calcite, 1 per cent iron oxide, and 1 per cent other components. It is texturally a medium-grained pellet phosphorite. ?? 1966.

  12. Geochemistry of rock units at the potential repository level, Yucca Mountain, Nevada

    USGS Publications Warehouse

    Peterman, Z.E.; Cloke, P.L.

    2002-01-01

    The compositional variability of the phenocryst-poor member of the 12.8 Ma Topopah Spring Tuff at the potential repository level was assessed by duplicate analysis of 20 core samples from the cross drift at Yucca Mountain, Nevada. Previous analyses of outcrop and core samples of the Topopah Spring Tuff showed that the phenocryst-poor rhyolite, which includes both lithophysal and nonlithophysal zones, is relatively uniform in composition. Analyses of rock samples from the cross drift, the first from the actual potential repository block, also indicate the chemical homogeneity of this unit excluding localized deposits of vapor-phase minerals and low-temperature calcite and opal in fractures, cavities, and faults. The possible influence of vapor-phase minerals and calcite and opal coatings on rock composition at a scale sufficiently large to incorporate these heterogeneously distributed deposits was evaluated and is considered to be relatively minor. Therefore, the composition of the phenocryst-poor member of the Topopah Spring Tuff is considered to be adequately represented by the analyses of samples from the cross drift. The mean composition as represented by the 10 most abundant oxides in wt. % or g/100 g is: SiO2, 76.29; Al2O3, 12.55; FeO, 0.14; Fe2O3, 0.97; MgO, 0.13; CaO, 0.50; Na2O, 3.52; K2O, 4.83; TiO2, 0.11; and MnO, 0.07. ?? 2002 Published by Elsevier Science Ltd.

  13. X-ray fluorescence analysis of rare earth elements in rocks using low dilution glass beads.

    PubMed

    Nakayama, Kenichi; Nakamura, Toshihiro

    2005-07-01

    Major and trace elements (Na, Mg, Al, Si, P, K, Ca, Ti, Mn, Fe, Rb, Sr, Y, Zr, La, Ce, Pr, Nd, Sm, Gd, Dy, Th and U) in igneous rocks were assayed with fused lithium borate glass beads using X-ray fluorescence spectrometry. Low dilution glass beads, which had a 1:1 sample-to-flux ratio, were prepared for determination of rare earth elements. Complete vitrification of 1:1 mixture required heating twice at 1200 degrees C with agitation. Extra pure reagents containing determinants were used for calibrating standards instead of the rock standard. The calibration curves of the 23 elements showed good linearity. Furthermore, the lower limits of detection corresponding to three times the standard deviation for blank measurements were 26 mass ppm for Na2O, 6.7 for MgO, 4.5 for Al2O3, 4.5 for SiO2, 18 for P2O5, 1.1 for K2O, 4.0 for CaO, 3.9 for TiO2, 1.6 for MnO, 0.8 for Fe2O3, 0.5 for Rb, 0.2 for Sr, 0.4 for Y, 0.5 for Zr, 3.3 for La, 6.5 for Ce, 2.7 for Pr, 2.1 for Nd, 1.7 for Sm, 0.7 for Gd, 2.7 for Dy, 0.5 for Th, and 0.6 for U. Using the present method, we determined the contents of these 23 elements in four rhyolitic and granitic rocks from Japan. PMID:16038502

  14. Toward Understanding the Effect of Nuclear Waste Glass Composition on Sulfur Solubility

    DOE PAGESBeta

    Vienna, John D.; Kim, Dong-Sang; Muller, I. S.; Kruger, Albert A.; Piepel, Gregory F.

    2014-10-01

    The concentration of sulfur in nuclear waste glass melter feed must be maintained below the point where salt accumulates on the melt surface. The allowable concentrations may range from 0.37 to over 2.05 weight percent (of SO3 on a calcined oxide basis) depending on the composition of the melter feed and processing conditions. If the amount of sulfur exceeds the melt tolerance level, a molten salt will accumulate, which may upset melter operations and potentially shorten the useful life of the melter. At the Hanford site, relatively conservative limits have been placed on sulfur loading in melter feed, which inmore »turn significantly increases the amount of glass that will be produced. Crucible-scale sulfur solubility data and scaled melter sulfur tolerance data have been collected on simulated Hanford waste glasses over the last 15 years. These data were compiled and analyzed. A model was developed to predict the solubility of SO3 in glass based on 252 simulated Hanford low-activity waste (LAW) glass compositions. This model represents the data well, accounting for over 85% of the variation in data, and was well validated. The model was also found to accurately predict the tolerance for sulfur in melter feed for 13 scaled melter tests of simulated LAW glasses. The model can be used to help estimate glass volumes and make informed decisions on process options. The model also gives quantitative estimates of component concentration effects on sulfur solubility. The components that most increase sulfur solubility are Li2O > V2O5> CaO ? P2O5 > Na2O ? B2O3 > K2O. The components that most decrease sulfur solubility are Cl > Cr2O3 > Al2O3 > ZrO2 ? SnO2 > Others ? SiO2. The order of component effects is similar to previous literature data, in most cases.« less

  15. Chemical modifications accompanying blueschist facies metamorphism of Franciscan conglomerates, Diablo Range, California

    USGS Publications Warehouse

    Moore, Diane E.; Liou, J.G.; King, B.-S.

    1981-01-01

    As part of an investigation of blueschist-facies mineral parageneses in pebbles and matrix of some Franciscan metaconglomerates of the Diablo Range, California, textural and major-element chemical analyses were conducted on a number of igneous pebbles that comprise a range of rock types from granite and dacite to gabbro and basalt. Compositions of the igneous pebbles differ significantly from common igneous rocks, particularly with respect to Ca, K, Na, Si and H2O. The SiO2 and H2O contents are characteristically high and the K2O contents low. The CaO and Na2O contents may be relatively enriched or reduced in different pebbles. The igneous pebbles show little evidence of alteration prior to their incorporation into the Franciscan conglomerates, and the chemical modifications are considered to have been produced during metamorphism of the conglomerates to (lawsonite + albite + aragonite ?? jadeite)-bearing assemblages. The observed variations in the pebbles are shown to be functions of: (1) bulk chemistry; (2) the igneous mineral assemblage; (3) the stable metamorphic mineral assemblage; and (4) the composition of pore fluids in the conglomerates. The relative proportions of Mg and Fe in most of the pebbles apparently have been unaffected by the metamorphism, and these parameters, along with other textural and chemical factors, were used to determine the petrogenetic affinities of the igneous pebbles. The plutonic and most of the volcanic pebbles correspond to calc-alkaline rock series, whereas a few volcanic pebbles show apparent Fe-enrichment characteristic of tholeiitic rocks. A continental margin arc-batholith complex would be the best source for these igneous detrital assemblages. Conglomerates in local areas differ in igneous lithologies from conglomerates in other areas and probably differ somewhat in age, perhaps reflecting varying degrees of unroofing of such a complex during deposition of Franciscan sediments. ?? 1981.

  16. Genesis of the Yuanlingzhai porphyry molybdenum deposit, Jiangxi province, South China: Constraints from petrochemistry and geochronology

    NASA Astrophysics Data System (ADS)

    Huang, Fan; Wang, Denghong; Santosh, M.; Wang, Chenghui; Zeng, Zailin; Liu, Shanbao; Wang, Liqiang; Zhang, Yongzhong

    2014-01-01

    The newly discovered Yuanlingzhai porphyry molybdenum (Mo) deposit in southern Jiangxi province belongs to the group of Mo-only deposits in the Nanling region. The mineralization developed at contact zones between the Yuanlingzhai granite porphyry and Neoproterozoic metamorphic rocks of the Xunwu Formation. Precise LA-MC-ICPMS zircon U-Pb dating of the Yuanlingzhai porphyry, as well as the adjacent western Keshubei and eastern Keshubei granites, yielded ages of 165.49 ± 0.59 Ma, 159.68 ± 0.43 Ma, and 185.13 ± 0.52-195.14 ± 0.63 Ma, respectively. Molybdenite Re-Os isochron ages of the ores are 160 ± 1-162.7 ± 1.1 Ma, which is consistent with the age of large-scale W-Sn deposits in South China. The Yuanlingzhai porphyry is characterized by high K2O, P2O5, and A/CNK (1.33-1.59), and low CaO and Na2O. The rock shows relatively enriched LREE without significant Eu anomalies (Eu/Eu* = 0.80-0.90). Geochemical and mineralogical characteristics indicate that the ore-hosting porphyry is a typical S-type granite generated from the partial melting of crustal material with only minor mantle contribution. Both Harker and evolutionary discrimination diagrams indicate that the Yuanlangzhai and western Keshubei granites are not products of co-magmatic evolution. The Keshubei granites and Xunwu Formation were not significant sources for the components in the porphyry mineralization, but the Yuanlangzhai granite may have supplied some ore-forming material. However, the main ore-forming material was carried by fluids from deep sources, as demonstrated by fluid inclusion and stable isotope data from the molybdenum deposit. The Mo porphyry deposit formed in an extensional setting, and was possibly associated with Jurassic subduction of the Izanagi Plate.

  17. Tertiary epizonal plutonic rocks of the Selway-Bitterroot Wilderness, Idaho County, Idaho

    SciTech Connect

    Motzer, W.E.

    1996-01-01

    Geologic mapping in the Selway-Bitterroot Wilderness identified approximately 731 kmS of epizonal plutonic granitic rocks within the Bitterroot lobe of the Idaho batholith. From north to south, the intrusions are the Rock Lake Creek stock and the Whistling Pig, Running Creek, Bad Luck and Painted Rocks plutons. The stock and plutons consist of medium- to coarse-grained biotite and hornblende-biotite syenorgranite to monzogranite and quartz syenite capped by fine-grained biotite leucogranite. These rocks are intruded by late-synplutonic leucogranite dikes and post plutonic porphyritic rhyolite to rhyodacite and basalt dikes. The medium-grained granitic rocks are high in SiO2, K2O, Na2O, Ga, Th, U, W and Zr, but low in Al7O3, CaO, MgO, Cr, Ni, Co and V. Most of the granites are peraluminous. Rare-earth element (REE) plots (rock sample/chondrite) show enrichment in light REE over heavy REE with strong EU depletions. K-Ar biotite radiometric age determinations for medium-grained granites in all of the plutons range from approximately 51 Ma (Whistling Pig pluton) to 43.7 Ma (Painted Rocks pluton). Petrogenetic studies suggest that the plutons were rapidly emplaced to within 3.0 km of the paleosurface. The types, textures and color of the rocks result from devolatilization of the crystallizing melt and very low-grade hydrothermal alteration. The fluorine-rich melts are the fractionated with accumulate residue; they are considered to be anorogenic (A-type) granites intruded into the center of a metamorphic core complex.

  18. Critical assessment of the elemental composition of Corning archeological reference glasses by LA-ICP-MS.

    PubMed

    Wagner, B; Nowak, A; Bulska, E; Hametner, K; Günther, D

    2012-02-01

    Corning archeological reference glasses A, B, C, and D have been made to simulate different historic technologies of glass production and are used as standards in historic glass investigations. In this work, nanoseconds (193, 266 nm) and femtosecond (800 nm) laser ablation were used to study the elemental composition of Corning glasses using laser ablation inductively coupled plasma mass spectrometry. The determined concentrations of 26 oxides (Li(2)O, B(2)O(3), Na(2)O, MgO, Al(2)O(3), SiO(2), P(2)O(5), K(2)O, CaO, TiO(2), V(2)O(5), Cr(2)O(3), MnO, Fe(2)O(3), CoO, NiO, CuO, ZnO, Rb(2)O, SrO, ZrO(2), SnO(2), Sb(2)O(5), BaO, PbO, Bi(2)O(3)) are compared with values reported in the literature. Results show variable discrepancies between the data, with the largest differences found for Cr(2)O(3) in Corning A; Li(2)O, B(2)O(3), and Cr(2)O(3) in Corning B; and MnO, Sb(2)O(5), Cr(2)O(3), and Bi(2)O(3) in Corning C. The best agreement between the measured and literature values was found for Corning D. However, even for this reference, glass re-evaluation of the data was necessary and new values for PbO, BaO, and Bi(2)O(3) are proposed. PMID:22159467

  19. Natural radionuclide concentrations in granite rocks in Aswan and Central-Southern Eastern Desert, Egypt and their radiological implications.

    PubMed

    Issa, Shams A M; Uosif, M A M; Abd el-Salam, L M

    2012-07-01

    Different types of granites, used extensively in local construction, were collected from five localities in Egypt, namely: Abu Ziran (Central Eastern Desert), Gabal El Maesala (Aswan) and three areas from Wadi Allaqi, (Gabal Abu Marw, Gabal Haumor and Gabal um Shalman), in the South Eastern Desert. Granite samples were studied radiologically, petrographically and geochemically. The contents of natural radionuclides ((226)Ra, (232)Th and (40)K) were measured in investigated samples by using gamma spectrometry [NaI (Tl) 3'×3']. The activity concentrations of (226)Ra, (232)Th and (40)K in the selected granite samples ranged from 9±0.5 to 111±7, 8±1 to 75±4 and 100±6 to 790±40 Bq kg(-1), respectively. The external hazard index (H(ex)), absorbed dose and annual effective dose rate were evaluated to assess the radiation hazard for people living in dwellings made of the materials studied. The calculated radium equivalents were lower than the values recommended for construction materials (370 Bq kg(-1)). The excess lifetime cancer risks were also calculated. Petrographically, the granites studied are varied in the form of potash-feldspar, quartz, plagioclase, mica and hornblende. The accessory minerals are zircon, apatite and allanite. Geochemically, the chemical composition of the granite is studied especially for major oxides. They are characterized to have SiO(2), K(2)O, Na(2)O and Al(2)O(3) with depletion in CaO, MgO, TiO(2) and P(2)O(5). PMID:22147926

  20. Characterization of the chemical constituents in Da-Huang-Gan-Cao-Tang by liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry and liquid chromatography coupled with ion trap mass spectrometry.

    PubMed

    Wang, Shufang; Chen, Pinghong; Xu, Yimin; Li, Xiaodong; Fan, Xiaohui

    2014-07-01

    In this work, the chemical constituents in Da-Huang-Gan-Cao-Tang, a traditional Chinese formula, were studied by liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry and liquid chromatography coupled with ion trap mass spectrometry for the first time. Among the 146 compounds detected in Da-Huang-Gan-Cao-Tang, 104 compounds were identified unambiguously or tentatively based on their accurate molecular weight and multistage MS data, including one potential novel compound and two reported in Glycyrrhiza genus for the first time. The possible fragmentation pathways were proposed and fragmentation rules of the major types of compounds were concluded. This study provided an example to facilitate the tedious identification of chemical composition in traditional Chinese medicine, and maybe a promising reference approach to research the analogous formulae. PMID:24771648

  1. Role of polaron hopping in leakage current behavior of a SrTiO3 single crystal Y. Cao, S. Bhattacharya, J. Shen, C. A. Randall, and L. Q. Chen

    E-print Network

    Chen, Long-Qing

    Role of polaron hopping in leakage current behavior of a SrTiO3 single crystal Y. Cao, S://scitation.aip.org/termsconditions. Downloaded to ] IP: 128.118.88.48 On: Sun, 02 Feb 2014 17:48:46 #12;Role of polaron hopping in leakage with the recent experimental observation. We introduced the possibility of polaron-hopping between Ti3þ and Ti4þ

  2. Role of CaO addition in the local order around Erbium in SiO2GeO2P2O5 fiber preforms F. d'Acapito C. Maurizio

    E-print Network

    Boyer, Edmond

    Role of CaO addition in the local order around Erbium in SiO2­GeO2­P2O5 fiber preforms F. d is drawn into a fiber. An effective method to study the incorporation of Er in a matrix is by Extended X and chemical composition of the environment of the element under study. The Er site has been successfully

  3. Effect of CaO on retention of S, Cl, Br, As, Mn, V, Cr, Ni, Cu, Zn, W and Pb in bottom ashes from fluidized-bed coal combustion power station.

    PubMed

    Barto?ová, Lucie; Klika, Zden?k

    2014-07-01

    This work was conducted to evaluate whether Ca-bearing additives used during coal combustion can also help with the retention of some other elements. This work was focused on the evaluation of bottom ashes collected during four full-scale combustion tests at an operating thermal fluidized-bed power station. Bottom ashes were preferred to fly ashes for the study to avoid interference from condensation processes usually occurring in the post-combustion zone. This work focused on the behaviors of S, Cl, Br, As, Mn, V, Cr, Ni, Cu, Zn, W, and Pb. Strong positive correlations with CaO content in bottom ashes were observed (for all four combustion tests) for S, As, Cl and Br (R=0.917-0.999). Strong inverse proportionality was calculated between the contents of Pb, Zn, Ni, Cr and Mn and CaO, so these elements showed association to materials other than Ca-bearing compounds (e.g., to aluminosilicates, organic matter, etc.). Somewhat unclear behaviors were observed for W, Cu, and V. Their correlation coefficients were evaluated as statistically "not significant", i.e., these elements were not thought to be significantly associated with CaO. It was also discovered that major enrichment of CaO in the finest bottom ash fractions could be advantageously used for simple separation of elements strongly associated with these fractions, mainly S and As, but also Cl or Br. Removal of 5% of the finest ash particles brings about a decrease in As concentration down to 77%-80% of its original bulk ash content, which can be conveniently used e.g., when high As content complicates further ash utilization. PMID:25079991

  4. Ab initio study of the positronation of the CaO and SrO molecules including calculation of annihilation rates.

    PubMed

    Buenker, Robert J; Liebermann, Heinz-Peter

    2012-07-15

    Ab initio multireference single- and double-excitation configuration interaction calculations have been performed to compute potential curves for ground and excited states of the CaO and SrO molecules and their positronic complexes, e(+)CaO, and e(+)SrO. The adiabatic dissociation limit for the (2)?(+) lowest states of the latter systems consists of the positive metal ion ground state (M(+)) and the OPs complex (e(+)O(-)), although the lowest energy limit is thought to be e(+)M + O. Good agreement is found between the calculated and experimental spectroscopic constants for the neutral diatomics wherever available. The positron affinity of the closed-shell X (1)?(+) ground states of both systems is found to lie in the 0.16-0.19 eV range, less than half the corresponding values for the lighter members of the alkaline earth monoxide series, BeO and MgO. Annihilation rates (ARs) have been calculated for all four positronated systems for the first time. The variation with bond distance is generally similar to what has been found earlier for the alkali monoxide series of positronic complexes, falling off gradually from the OPs AR value at their respective dissociation limits. The e(+)SrO system shows some exceptional behavior, however, with its AR value reaching a minimum at a relatively large bond distance and then rising to more than twice the OPs value close to its equilibrium distance. PMID:22522712

  5. Magnetic interactions in the catalyst used by nature to split water: a DFT + U multiscale study on the Mn4CaO5 core in photosystem II

    NASA Astrophysics Data System (ADS)

    Bovi, Daniele; Narzi, Daniele; Guidoni, Leonardo

    2014-01-01

    An important approach in the design of new environmentally friendly materials is represented by the study of analogous systems already existing in nature. In the search for new water splitting catalysts, the corresponding natural analogue is represented by the oxygen-evolving complex of photosystem II, which is a large membrane protein complex present in photosynthetic organisms. The understanding of the catalytic strategy of its active Mn4CaO5 core is important to unravel the mechanisms of water oxidation in photosynthesis and can serve as an inspiring model for the design of biomimetic catalysts based on largely non-toxic, earth abundant elements. The magnetic interactions between Mn ions are studied in the present work by means of DFT + U broken symmetry ab initio molecular dynamics within a quantum mechanics/molecular mechanics framework. The room temperature dynamics of two different structural models (i.e. with total high-spin and total low-spin ground states) was stable during the simulated time. We observed large fluctuations of the magnetic coupling constants calculated on both the structural models of the complex, causing occasionally instantaneous swapping of the ferromagnetic/antiferromagnetic coupling between the metal centers.

  6. Comparison of CaO's effect on the fate of heavy metals during thermal treatment of two typical types of MSWI fly ashes in China.

    PubMed

    Hu, Hong-Yun; Liu, Huan; Shen, Wen-Qing; Luo, Guang-Qian; Li, Ai-Jun; Lu, Zhao-Ling; Yao, Hong

    2013-10-01

    Both grate and fluidized bed incinerators are widely used for MSW incineration in China. CaO addition for removing hazardous emissions from MSWI flue gas changes the characteristics of fly ash and affects the thermal behavior of heavy metals when the ash is reheated. In the present work, two types of MSWI fly ashes, sampled from both grate and fluidized bed incinerators respectively, were thermal treated at 1023-1323 K and the fate of heavy metals was observed. The results show that both of the fly ashes were rich in Ca and Ca-compounds were the main alkaline matter which strongly affected the leaching behavior of heavy metals. Ca was mostly in the forms of Ca(OH)2 and CaCO3 in the fly ash from grate incinerator in which nascent fly ash particles were covered by Ca-compounds. In contrast, the content of Ca was lower in the fly ash from fluidized bed incinerator and Ca was mostly in the form of CaSO4. Chemical reactions among Ca-compounds caused particle agglomeration in thermal treated fly ash from grate incinerator, restraining the heavy metals volatilization. In thermal treated fly ash from fluidized bed incinerator, Ca was converted into aluminosilicates especially at 1323 K which enhanced heavy metals immobilization, decreasing their volatile fractions as well as leaching concentrations. Particle agglomeration hardly affected the leaching behavior of heavy metals. However, it suppressed the leachable-CaCrO4 formation and lowered Cr leaching concentration. PMID:23800595

  7. Condensation of CaO sbnd MgO sbnd Al 2O 3sbnd SiO 2 liquids from cosmic gases

    NASA Astrophysics Data System (ADS)

    Yoneda, Shigekazu; Grossman, Lawrence

    1995-08-01

    The Berman (1983) activity-composition model for non-ideal liquid solutions in the CaO sbnd MgO sbnd Al 2O 3sbnd SiO 2 (CMAS) system is incorporated into equilibrium condensation calculations which are used to explore the vapor-solid-liquid stability relations as a function of temperature and total pressure ( Ptot) in a gas of solar composition, and as a function of temperature and dust/gas ratio at Ptot = 1 × 10 -3 atm in gases produced by total vaporization of systems enriched in interstellar dust relative to the gas compared to solar abundances. Condensate liquids are very non-ideal, suggesting that results of previous attempts to model their formation using ideal solution models are highly inaccurate. As is the case for the Berman (1983) liquid model itself, results of the present calculations are in very good agreement with experimentally determined liquid-crystal phase relations except where intermediate members of solid solution series, such as melilite and fassaite, are predicted to be in equilibrium with liquid, in which cases liquid-crystal equilibration temperatures are overestimated by 50 to 100 K. CMAS liquids are stable in a solar gas at a Ptot at least as low as 5 × 10 -2 atm and perhaps as low as 1 × 10 -2 atnt, much lower than previous estimates for liquids of pure forsterite composition, due to the colligative effects of CaO and Al 20 3. CMAS liquids are stable at Ptot = 1 × 10 -3 atm in systems with dust/gas enrichment factors at least as low as 16 and perhaps as low as 5 relative to solar abundances. Results of these calculations suggest that, upon cooling, a solid melilite + spinel condensate assemblage, comparable to a Type A refractory inclusion, would react with the vapor to produce a liquid much richer in MgO and SiO 2 than the starting material, at either elevated Ptot or enhanced dust/gas ratio. If this partial melt were isolated from further reaction with the nebular gas, it would solidify into a spinel + melilite + fassaite + anorthite assemblage, similar in chemical and mineralogical composition to a Type B refractory inclusion. Forsterite coexists stably with CMAS condensate liquids over wide ranges of Ptot and dust/gas ratio, extending to the lowest Ptot and dust/gas ratio at which liquids are stable. If the compositions of glass inclusions inside isolated forsterite crystals in the Murchison CM2 chondrite have been modified by precipitation of 25 wt% forsterite as a daughter mineral from the liquid precursors of those glasses, the inclusions could represent condensate liquids that were in equilibrium with forsterite at Ptot = 0.3 atm or at dust/gas enrichment factors of ˜70 at Ptot = 1 × 10 -3 atm.

  8. Oxidation Studies of SiAlON/MgAlON Ceramics with Fe2O3 and CaO Impurities, Part II: Phase Evolution

    NASA Astrophysics Data System (ADS)

    Li, Peng; Zhang, Mei; Teng, Lidong; Seetharaman, Seshadri

    2013-02-01

    The oxidation behavior of composite SiAlON/MgAlON phases, synthesized from the leaching residue after the aqueous treatment of salt cake from aluminum remelting, is compared with the oxidation of corresponding synthetic samples. The samples were subjected to oxidation under air as the oxidant atmosphere in the temperature range of 1373 K to 1773 K (1100 °C to 1500 °C). The phases present were analyzed by scanning electron microscopy (SEM)-electron-dispersive spectroscopy (EDS) and X-ray diffraction (XRD) to arrive at the evolution of the various phases formed during oxidation. From the experimental results, especially by the characterization of the oxidation products, the mechanism of the oxidation reaction was deduced as follows: With the progress of oxidation, the composition of the material being oxidized moved toward the Al2O3-rich corner of MgO-Al2O3-SiO2 and CaO-MgO-Al2O3-SiO2 phase diagrams relevant to the SiAlON/MgAlON composite. At lower temperatures, the addition of Fe2O3 and CaO facilitated the formation of cordierite and anorthite, respectively. With increasing temperature, islands of silicate melt were formed dissolving these oxides, with the liquidus temperature getting lowered as a consequence. The liquid phase formed engulfed the adjacent solid phases providing strong mobility for the cations and enabling the crystal growth. As a result, intermediate products, i.e., cordierite, anorthite, and spinel, which were formed earlier during oxidation, are found to get dissolved in the liquid phase.

  9. Tree species identification in an African Savanna with airborne imaging spectroscopy and LiDAR from the Carnegie Airborne Observatory (CAO) using stacked support vector machines

    NASA Astrophysics Data System (ADS)

    Baldeck, C. A.; Colgan, M.; Féret, J.; Asner, G. P.

    2012-12-01

    Airborne remote sensing data provide promising opportunities for species identification of individual tree and shrub crowns across large areas which cannot be mapped from the ground. Previous investigations of the potential for species identification of crowns from airborne data have focused on pixel-level information (0.5-1m2), and thus have been unable to take advantage of the structural information that exist at the crown level. Hyperspectral data consisting of 58 bands from 517 to 1054nm and LiDAR (light detection and ranging) data providing vegetation height information were acquired over several landscapes within Kruger National Park, South Africa, by the CAO in 2008 at 1.1m spatial resolution. Over 1,000 individual trees and shrubs were mapped and identified in the field to construct species spectral and structural libraries. We used stacked support vector machines (SVM) that incorporate pixel-level spectral information and crown-level structural information to predict species identity for individual tree crowns. The addition of a crown-level classification step that incorporates crown structural information significantly improved model accuracy by ~6% and our prediction accuracy of the final model was ~75% for 16 species classes. This model was then used to predict the species identity of individual crowns across multiple airborne-mapped landscapes, made possible by an automated crown segmentation algorithm. The resultant species maps will make it possible to examine the environmental controls over individual species distributions and tree community composition, and provide important landscape-scale species distribution information relevant to park management and conservation.

  10. Synthetic model of the asymmetric [Mn3CaO4] cubane core of the oxygen-evolving complex of photosystem II

    PubMed Central

    Mukherjee, Shreya; Stull, Jamie A.; Yano, Junko; Stamatatos, Theocharis C.; Pringouri, Konstantina; Stich, Troy A.; Abboud, Khalil A.; Britt, R. David; Yachandra, Vittal K.; Christou, George

    2012-01-01

    The laboratory synthesis of the oxygen-evolving complex (OEC) of photosystem II has been the objective of synthetic chemists since the early 1970s. However, the absence of structural information on the OEC has hampered these efforts. Crystallographic reports on photosystem II that have been appearing at ever-improving resolution over the past ten years have finally provided invaluable structural information on the OEC and show that it comprises a [Mn3CaO4] distorted cubane, to which is attached a fourth, external Mn atom, and the whole unit attached to polypeptides primarily by aspartate and glutamate carboxylate groups. Such a heterometallic Mn/Ca cubane with an additional metal attached to it has been unknown in the literature. This paper reports the laboratory synthesis of such an asymmetric cubane-containing compound with a bound external metal atom, [(1)] . All peripheral ligands are carboxylate or carboxylic acid groups. Variable-temperature magnetic susceptibility data have established 1 to possess an S = 9/2 ground state. EPR spectroscopy confirms this, and the Davies electron nuclear double resonance data reveal similar hyperfine couplings to those of other MnIV species, including the OEC S2 state. Comparison of the X-ray absorption data with those for the OEC reveal 1 to possess structural parameters that make it a close structural model of the asymmetric-cubane OEC unit. This geometric and electronic structural correspondence opens up a new front in the multidisciplinary study of the properties and function of this important biological unit. PMID:22308383

  11. Geochemical Characteristics of Ultramafic Rocks From Main Hole of CCSDP, Sulu UHPM Belt

    NASA Astrophysics Data System (ADS)

    Li, T.; Yang, J.; Xu, Z.; Chen, S.

    2004-12-01

    In the main hole of Chinese Continental Scientific Drilling Project (CCSDP), the ultramafic rocks, hosted by rutile eclogite, occur at the depth between 603.2 ˜.683.5 m. Ultramafic rocks are composed of mainly wehrlite and minor lherzolite. Most of these rocks contain abundant garnet and Ti-clinohumite, but minor rocks have no garnet and Ti-clinohumite. Serpentinization varies in different degrees ,through the depth and minor talc and prehnite, present mainly at the lowermost part of the profile. Besides, there is a 10 m thick layer and many thin lens of rutile phengite eclogite, as well as small blocks of eclogite and thin layers of phlogopite orthopyroxenite and megacrystic amphibolite in the ultramfic sequence. The contacts between the ultramafic rocks and hosting eclogite and lens in them are sharp. The uppermost ultramafic rock possibly has a tectonic contact, with the host eclogite, characterized by mixed agglomerates of them. Major element concentrations of wehrlite and its altered product serpentinite range between SiO2 40.60% ˜.43.42%, TiO2<0.31%, Al2O3 3.16% ˜.8.96%, total FeO 12.27% ˜.16.77%, MnO 0.18% ˜.0.27%, MgO 27.65% ˜.39.20%, CaO 1.02% ˜.5.32%, Na2O 0.01% ˜.0.74%, K2O 0.01% ˜.0.81% and P2O5 0.01% ˜.0.12%. The average fusible compositions are fairly high(TiO2 0.21% Al2O3 5.06% CaO 2.53% and Na2O 0.25%) and closing to or exceeding the corresponding compositions of primary mantle .Representative refractory composition MgO is lower than that of primary mantle. MgO is lower and varies narrowly between 77.26 ˜.85.07. When compared with A type Zhimafang peridotite(Zhang et al, 2000), the wehrlite in borehole has relatively lower SiO2 and MgO and higher TiO2, Al2O3, CaO and total FeO. In a word, wehrlite shows more fertile characteristics. Total REE concentrations range 4.38×10-6 ˜.43.26×10-6, most of which are higher than that of primary mantle(PM, 6.86×10-6). Most of the samples show moderate LREE enriched characteristics with £"La/Yb£cN ratios of 1.02 ˜21.03 and slight Eu positive anomaly in PM normalized partition pattern diargram. Trace element spider diagram shows no evident incline with £"Rb/Yb£cN ratios of 0.25 ˜.2.98, but has U, La, Zr, Hf and Sr positive anomalies and Ba, Nb and Ta negative anomalies. Tatol content of PGE is very low ranging between 1.14×10-9 ˜.2.72×10-9 which are fairly lower than that of primary mantle(23.5×10-9), that of mantle xenoliths in Cenozoic basalt in East China(16.5×10-9 ˜.50.7×10-9) and that of Ronda peridotite. All the data above indicate that the protolith of wehrlite was possibly not a residual mantle block but a ultrmafic body in the crustal depth, i. e. , B type ultramafic body in UHP belt.

  12. O(-) identified at high temperatures in CaO-based catalysts for oxidative methane dimerization

    NASA Technical Reports Server (NTRS)

    Freund, F.; Maiti, G. C.; Batllo, F.; Baerns, M.

    1990-01-01

    A technique called charge-distribution analysis (CDA) is employed to study mobile charge carriers in the oxidation catalysts CaO, CaO with 11 percent Na2O, and CaO with 10 percent La2O3. A threshold temperature of about 550-600 C is identified at which highly mobile charge carriers are present, and the CDA studies show that they are O(-) states. The present investigation indicates the usefulness of CDA in catalysis research with pressed powder samples and gas/solid reactions.

  13. Curriculum Vitae Hui Cao 1 Hui Cao June 6, 2010

    E-print Network

    Cao, Hui

    Goeppert-Mayer Award from American Physical Society 2006 Friedrich Wilhelm Bessel Research Award from 2005 Lecturer 2008 Fellow of American Physical Society 2007 Fellow of Optical Society of America 2007 Maria

  14. Curriculum Vitae Hui Cao 1 Hui Cao Aug. 22, 2013

    E-print Network

    Cao, Hui

    & Aerospace Engineering 1992 B.S. Peking University Physics 1990 Predoctoral awards and fellowships Karel and A. W. Poon, World Scientific, Advanced Series in Applied Physics Vol. 6, pp. 205-251 (2011). 8. H", Chapter 5 in "Handbook of Luminescent Semiconductor Materials", ed. L. Bergman and J. L. McHale, CRC Press

  15. Geochemistry and petrogenesis of Paleo-Proterozoic granitoids from Mahakoshal Supracrustal Belt (MSB), CITZ

    NASA Astrophysics Data System (ADS)

    Yadav, Bhupendra; Ahmad, Talat; Kaulina, Tatiana; Bayanova, Tamara

    2015-04-01

    Voluminous granitic magmatism of Proterozoic age occupies a vast expanse at the southern margin of Mahakoshal Supracrustal Belt (MSB), CITZ. The present study focuses on eastern part of this belt and discusses possible crustal evolution processes based on the geochemical, geochronological and Sm-Nd isotopic constraints on these rocks. The rocks present are predominantly granites and gneisses viz. grey to pink granite gneiss and leuco- to mesocratic granites. In general these rocks are medium to coarse grained and microscopically show typical granitic assemblages with apatite, titanite, zircon and allanite as accessories. Mineralogically these rocks are grouped into three categories viz. Hbl-Bt granite gneiss, Bt- granite gneiss and Bt-granite. Major oxide characteristics show that the Hbl-Bt granite Gneiss are metaluminous (ASI~0.98), whereas Bt- granite gneiss (ASI=1.05-1.22) and Bt- granite (ASI=1.03-1.21) are weakly peraluminous to strongly peraluminous. In terms of Fe* number and alkali-lime index these rocks belong to magnesian and calc-alkalic series respectively. Overall these rocks range from 59.43 to 72.01 wt.% SiO2 and have low Na2O content (average ~2.60 wt.%) with average ~4.02 wt.% K2O and high K2O/Na2O ratio. On Harker variation diagrams, all rock types show negative correlation for TiO2, P2O5, CaO, MnO, MgO, Fe2O3T and Al2O3 against SiO2 suggesting fractionation of Pl-Hbl-Ttn-Mag-Ap during evolution of these rocks. On chondrite-normalized Rare Earth Element (REE) plot, the Bt-granite is enriched in LREE ((La/Sm)N ~10.21) and show negative Eu anomaly (Eu/Eu*=0.39) with depleted HREE ((Gd/Yb)N ~4.38). The Hbl-Bt granite gneiss shows LREE ((La/Sm)N ~6.68) depletion and enriched HREE ((Gd/Yb)N ~2.05) patterns compared to Bt-granite, with negative Eu anomaly (Eu/Eu*=0.44). Whereas Bt-gneiss is moderate in comparison with LREE enrichment ((La/Sm)N ~9.17) and HREE depletion ((Gd/Yb)N ~3.02) with weak negative Eu anomaly (Eu/Eu*=0.60). Multi-elemental plot shown for all rocks have positive U, Th and Pb anomalies and negative Nb and Ti anomalies, commonly interpreted as continental crust involvement in their genesis. Sm-Nd analysis on two samples of Hbl-Bt granite gneiss show143Nd/144Nd ratio ranges from 0.511384-0.511394 with a corresponding 147Sm/144Nd ratio of 0.118109-0.118762. The analyzed samples yield TDM model ages of 2807-2804 Ma with present day É?Nd values being negative, whereas the initial É?Nd values (calculated at TDM ages) are positive. The positive initial epsilon values indicate its derivation from depleted mantle source but this magma must have incorporated crustal material during their ascent and probably had a longer crustal residence time to have the observed evolved É?Ndlower values. However 143Nd/144Nd ratios when compared with present day enriched mantle values of EM-I (

  16. Crystallization of tholeiitic basalt in Alae Lava Lake, Hawaii

    USGS Publications Warehouse

    Peck, D.L.; Wright, T.L.; Moore, J.G.

    1966-01-01

    The eruption of Kilauea Volcano August 21-23, 1963, left 600,000 cubic meters of basaltic lava in a lava lake as much as 15 meters deep in Alae pit crater. Field studies of the lake began August 27 and include repeated core drilling, measurements of temperature in the crust and melt, and precise level surveys of the lake surface. The last interstitial melt in the lake solidified late in September 1964; by mid August 1965 the maximum temperature was 690??C at a depth of 11.5 meters. Pumice air-quenched from about 1140??C contains only 5 percent crystals - clinopyroxene, cuhedral olivine (Fo 80), and a trace of plagioclase, (An 70). Drill cores taken from the zone of crystallization in the lake show that olivine continued crystallizing to about 1070??C; below that it reacts with the melt, becoming corroded and mantled by pyroxene and plagioclase. Below 1070??C, pyroxene and plagioclase crystallized at a constant ratio. Ilmenite first appeared at about 1070??C and was joined by magnetite at about 1050??C; both increased rapidly in abundance to 1000??C. Apatite first appeared as minute needles in interstitial glass at 1000??C. Both the abundance and index of refraction of glass quenched from melt decreased nearly linearly with falling temperature. At 1070??C the quenched lava contains about 65 percent dark-brown glass with an index of 1.61; at 980??C it contains about 8 percent colorless glass with an index of 1.49. Below 980??C, the percentage of glass remained constant. Progressive crystallization forced exsolution of gases from the melt fraction; these formed vesicles and angular pores, causing expansion of the crystallizing lava and lifting the surface of the central part of the lake an average of 19.5 cm. The solidified basalt underwent pneumatolitic alteration, including deposition of cristobalite at 800??C, reddish alteration of olivine at 700??C, tarnishing of ilmenite at 550??C, deposition of anhydrite at 250??C, and deposition of native sulfur at 100??C. Ferric-ferrous ratios suggest that oxidation with maximum intensity between 550??C and 610??C moved downward in the crust as it cooled; this was followed by reduction at a temperature of about 100??C. The crystallized basalt is a homogeneous fine-grained rock containing on the average 48.3 percent by volume intergranular pyroxene (augite > pigeonite), 34.2 percent plagioclase laths (An60 70), 7.9 percent interstitial glass, 6.9 percent opaques (ilmenite > magnetite), 2.7 percent olivine (Fo70 80), and a trace of apatite. Chemical analyses of 18 samples, ranging from initially quenched pumice to lava cored more than a year after the eruption from the center and from near the base of the lake, show little variation from silica-saturated tholeiitic basalt containing 50.4 percent SiO2, 2.4 percent Na2O, and 0.54 percent K2O. Apparently there was no significant crystal settling and no appreciable vapor-phase transport of these components during the year of crystallization. However, seven samples of interstitial liquid that had been filter-pressed into gash fractures and drill holes from partly crystalline mush near the base of the crust show large differences from the bulk composition of the solidified crust-lower MgO, CaO, and Al2O3; and higher total iron, TiO2, Na2O, K2O, P2O5, and F, and, in most samples, SiO2. The minor elements Ba, Ga, Li, Y, and Yb and possibly Cu tend to be enriched in the filter-pressed liquids, and Cr and possibly Ni tend to be depleted. ?? 1966 Stabilimento Tipografico Francesco Giannini & Figli.

  17. Physico-chemical conditions of crystallization of the Guli ulrabasic massif (North Part of the Siberian Platform): evidence from melt inclusions

    NASA Astrophysics Data System (ADS)

    Simonov, Vladimir; Vasiliev, Yuri; Kotlyarov, Alexey; Stupakov, Sergey

    2014-05-01

    Conditions of formation of the Guli ultrabasic massif (Maimecha Kotui Province in the North Part of the Siberian Platform) attract attention of numerous researchers. For the solution of genetic problems of various rocks from this ultramafic complex the data on melt inclusions in minerals has been earlier used (Sokolov et al., 1999; Rass, Plechov, 2000; Sokolov, 2003; Panina, 2006). At the same time, formation of dunites, occupying the main volume of the Guli massif, remain almost not considered by means of thermobarogeochemical methods and the role of magmatic processes in this case is not ascertained. As a result of melt inclusions study in the Cr-spinel the new data on physical and chemical parameters of dunite crystallization in the Guli ulrabasic massif was obtained. On the ratio (Na2O + K2O) - SiO2 the majority of analyses of glasses and calculated compositions of inclusions settle down in the field of subalkaline series. On the diagram MgO - SiO2 bulk chemical compositions of inclusions (with the magnesium content of 19-28 wt. %) correspond to picrites and picrite-basalts. They are in close association with the data on inclusions in the Cr-spinel from dunites of Konder (Siberian Platform) and Nizhnii Tagil (Ural Mountains) platinum-bearing ultrabasic massifs and also are situated near to the field of inclusions in the olivine phenocrysts from meimechites (Maimecha Kotui Province in the North Part of the Siberian Platform). Similarity of melt inclusions in the Cr-spinel from the dunite of the Guli massif and in the olivine from meimechites is established on the variety of petrochemical components - Al2O3, CaO, Na2O, K2O. The calculated compositions of inclusions from dunites coincide mostly with the data on inclusions from meimechites, while glasses of inclusions from Cr-spinel contain less titan and magnesium. As a whole for the melts of the Maimecha Kotui Province (that form both dunites of the Guli massif and meimechites) much higher contents of TiO2 (from above 2.7 wt. %) are characteristic in comparison with magmatic systems of the platinum-bearing ultrabasic massifs of Ural and Siberia. Our computer simulations on the basis of melt inclusion compositions by the PETROLOG program package (Danyushevsky, Plechov, 2011) show the high crystallization temperature of olivines from dunites of the Guli massif in the intrusive chamber - 1590-1415 °C. Formation of the Cr-spinels occurred also at high parameters - 1405-1365 °C. These temperatures correspond to established earlier temperature interval of crystallization of olivines from meimechites - 1600-1420 °C (Sobolev et al., 1999, 2009). As a whole, the melt inclusions study in the Cr-spinel directly testify to formation of dunites from the Guli massif from high magnesia melt, relative on its petrochemical composition and high-temperature characteristics to meimechite magma. Consecutive evolution of composition of magmatic systems is established during intra-chamber crystallization of dunites from picrite-meimechite to picrite-basalt and basalt melts. The investigations were supported by the Project N VIII.66.1.1 and by the Russian Foundation for Basic Research (Project N 12-05-00959).

  18. Processing, characterisation and biocompatibility of iron-phosphate glass fibres for tissue engineering

    Microsoft Academic Search

    I. Ahmed; C. A. Collins; M. P. Lewis; I. Olsen; J. C. Knowles

    2004-01-01

    Iron-phosphate glass fibres based on the CaO–Na2O–Fe2O3–P2O5 system have been processed and characterised via thermal, XRPD, dissolution rates, diameter and biocompatibility studies. The compositions investigated were fixed at 50mol% P2O5, and the CaO content was varied between 30, 35 and 40mol%. The Fe2O3 was added in low amounts from 1–5mol%, substituting it for the Na2O mol%.The number of Tc (crystallisation

  19. The Effect of Chlorine on the Rheology of Na2O-Fe2O3Al2O3SiO2 Melts

    Microsoft Academic Search

    M. Zimova; S. Webb

    2004-01-01

    Because of the high fluid mobility of chlorine, the mantle wedge in subduction zone settings may be enriched in chlorine by the fluids released by the subducted altered oceanic crust plus sediments. The presence of chlorine (and other halogens) will affect the solidus temperature and the rheology of melts, thus influencing the magma evolution, eruption and degassing. Very little is

  20. Alkali activation of fly ash: Effect of the SiO2\\/Na2O ratioPart I: FTIR study

    Microsoft Academic Search

    M. Criado; A. Fernández-Jiménez; A. Palomo

    2007-01-01

    In this paper the main reaction products formed in alkali activated fly ash systems have been studied by using Infrared Spectroscopy. The main variables of work were: soluble silica content in the alkaline activating solution (0% SiO2; 1.62% SiO2; 5.40% SiO2 and 9.07% SiO2) and thermal curing time (8 h, 60 and 180 days). The results obtained have shown that

  1. An XRD study of the effect of the SiO 2\\/Na 2O ratio on the alkali activation of fly ash

    Microsoft Academic Search

    M. Criado; A. Fernández-Jiménez; A. G. de la Torre; M. A. G. Aranda; A. Palomo

    2007-01-01

    Soluble silica has a very significant effect on the microstructural and mechanical development of the cementitious materials produced as a result of the alkali activation of fly ash. In this study, four different alkaline solutions with different soluble silica contents were used to activate fly ash. The primary reaction product was a sodium aluminosilicate gel, while different types of zeolites

  2. The thermal stability of sideronatrite and its decomposition products in the system Na2O-Fe2O3-SO2-H2O

    NASA Astrophysics Data System (ADS)

    Ventruti, Gennaro; Scordari, Fernando; Della Ventura, Giancarlo; Bellatreccia, Fabio; Gualtieri, Alessandro F.; Lausi, Andrea

    2013-09-01

    The thermal stability of sideronatrite, ideally Na2Fe3+(SO4)2(OH)·3(H2O), and its decomposition products were investigated by combining thermogravimetric and differential thermal analysis, in situ high-temperature X-ray powder diffraction (HT-XRPD) and Fourier transform infrared spectroscopy (HT-FTIR). The data show that for increasing temperature there are four main dehydration/transformation steps in sideronatrite: (a) between 30 and 40 °C sideronatrite transforms into metasideronatrite after the loss of two water molecules; both XRD and FTIR suggest that this transformation occurs via minor adjustments in the building block. (b) between 120 and 300 °C metasideronatrite transforms into metasideronatrite II, a still poorly characterized phase with possible orthorhombic symmetry, consequently to the loss of an additional water molecule; X-ray diffraction data suggest that metasideronatrite disappears from the assemblage above 175 °C. (c) between 315 and 415 °C metasideronatrite II transforms into the anhydrous Na3Fe(SO4)3 compound. This step occurs via the loss of hydroxyl groups that involves the breakdown of the [Fe3+(SO4)2(OH)]{?/2-} chains and the formation of an intermediate transient amorphous phase precursor of Na3Fe(SO4)3. (d) for T > 500 °C, the Na3Fe(SO4)3 compound is replaced by the Na-sulfate thenardite, Na2SO4, plus Fe-oxides, according to the Na3Fe3+(SO4)3 ? 3/2 Na2(SO4) + 1/2 Fe2O3 + SOx reaction products. The Na-Fe sulfate disappears around 540 °C. For higher temperatures, the Na-sulfates decomposes and only hematite survives in the final product. The understanding of the thermal behavior of minerals such as sideronatrite and related sulfates is important both from an environmental point of view, due to the presence of these phases in evaporitic deposits, soils and sediments including extraterrestrial occurrences, and from the technological point of view, due to the use of these materials in many industrial applications.

  3. Enhancement of luminescence properties in Er3+ doped TeO2-Na2O-PbX (X=O and F) ternary glasses.

    PubMed

    Kumar, Kaushal; Rai, S B; Rai, D K

    2007-04-01

    An enhancement of luminescence properties in Er3+ doped ternary glasses is observed on the addition of PbO/PbF2. The infrared to visible upconversion emission bands are observed at 410, 525, 550 and 658 nm, due to the 2H9/2-->4I15/2, 2H11/2-->4I15/2, 4S3/2-->4I15/2, 4F9/2-->4I15/2 transitions respectively, on excitation with 797 nm laser line. A detailed study reveals that the 2H9/2-->4I15/2 transition arises due to three step upconversion process while other transitions arise due to two step absorption. On excitation with 532 nm radiation, ultraviolet and violet upconversion bands centered at 380, 404, 410 and 475 nm wavelengths are observed along with one photon luminescence bands at 525, 550, 658 and 843 nm wavelengths. These bands are found due to the 4G11/2-->4I15/2, 2P3/2-->4I13/2, 2H9/2-->4I15/2, 2P3/2-->4I11/2, 2H11/2-->4I15/2, 4S3/2-->4I15/2, 4F9/2-->4I15/2 and 4S3/2-->4I13/2 transitions, respectively. Though incorporation of PbO and PbF2 both enhances fluorescence intensities however, PbF2 content has an important influence on upconversion luminescence emission. The incorporation of PbF2 enhances the red emission (658 nm) intensity by 1.5 times and the violet emission (410 nm) intensity by 2.0 times. A concentration dependence study of fluorescence reveals the rapid increase in the red (4F9/2-->4I15/2) emission intensity relative to the green (4S3/2-->4I15/2) emission with increase in the Er3+ ion concentration. This behaviour has been explained in terms of an energy transfer by relaxation between excited ions. PMID:16872889

  4. Towards a quantum-chemical description of crystalline insulators: A Wannier-function-based Hartree-Fock study of Li2O and Na2O

    E-print Network

    Birkenheuer, Uwe

    Towards a quantum-chemical description of crystalline insulators: A Wannier-function-based Hartree with the values obtained by a traditional Bloch-orbital-based Hartree-Fock approach. The present Wannier-function 51519-X I. INTRODUCTION A typical quantum-chemical investigation of a system, employing a wave-function

  5. Moessbauer Effect Study of Bi2O3. Na2O. B2O3. Fe2O3 Glass System

    SciTech Connect

    Salah, S.H.; Kashif, I.; Salem, S.M.; Mostafa, A.G.; El-Manakhly, K.A. [Physics and Chemistry Dept., Faculty of Science, Al-Azhar Univ., Cairo (11884) (Egypt)

    2005-04-26

    Sodium-tetra-borate host glass containing both bismuth and iron cations were prepared obeying the composition (Na2B4O7)0.75 (Fe2O3)0.25-x (Bi2O3)x [where x = 0.0, 0.05, 0.10, 0.15, 0.20, and 0.25 mol.%]. X-ray diffraction indicated that all samples were in a homogeneous glassy phase. Moessbauer effect results showed that all iron ions appeared as Fe3+ ions occupying tetrahedral coordination state. The covalency of the Fe-O bond increased as bismuth oxide was gradually increased. IR measurements indicated the presence of some non-bridging oxygens and confirmed that iron ions occupy the tetrahedral coordination state. It was found also that, as Bi2O3 was gradually increased both magnetic susceptibility and specific volume decreased, while both density and molar volume increased.

  6. Geochemical characterization of migmatized orthogneiss from Porto Ottiolu (NE Sardinia, Italy) and its inferences on partial melting process

    NASA Astrophysics Data System (ADS)

    Cruciani, Gabriele; Fancello, Dario; Franceschelli, Marcello; Columbu, Stefano

    2015-04-01

    Migmatites are very common in the northern part of the axial zone of the Sardinia Variscan chain. At Porto Ottiolu, about 30 km south of Olbia, a wide sequence of igneous- and sedimentary-derived migmatites crops out. Migmatized orthogneiss have a complex structural evolution characterized by three folding phases (D1, D2, D3) followed by a shear deformation. The oldest structure observed in the migmatites is a gneissose layering (D1). The second deformation (D2) is the most pervasive in the field and produces tight folds. D3 deformation caused symmetric folds with sub-horizontal axes. The leucosomes are coarse-grained, centimetre-thick, deformed leucocratic layers and/or patches following or cutting the D2 foliation. Other leucosomes are emplaced along shear zones (S4). The mesosomes are medium-grained foliated rocks in which the foliation is identified by biotite oriented along the S2 schistosity. The contact between mesosome and leucosome is frequently marked by thin biotite-rich selvedge. Leucosomes mainly consist of quartz, plagioclase, K-feldspar, minor biotite, muscovite and rare garnet. Mesosomes consist of the same mineral assemblage but they are rich in biotite and muscovite. Muscovite is found as submillimetre-sized crystals with variable phengitic component (Si: 6.1, Fe: 0.14, Mg: 0.13 a.p.f.u., XMg: 0.48 in less phengitic crystals, Si: 6.2, Fe: 0.18, Mg: 0.20 a.p.f.u., XMg: 0.53 in more phengitic ones). Biotite is titanium rich (Ti 0.3 a.p.f.u.) and has XMg 0.4. Very rare garnet occurs as submillimetric unzoned almandine with high manganese and low calcium content (Alm: 79mol.%; Prp: 5; Sps: 11-13; Grs: 3). Plagioclase is an unzoned oligoclase (XAb: 0.7), sometimes surrounded by a thin rim of pure albite. K-feldspar often shows perthitic exsolutions. The modal amount of feldspars varies significantly within the same leucosome and between different leucosomes. In particular, leucosomes along shear zones are feldspar rich. Evidences of melting are given by the occurrence of myrmekitic miscrostructures between quartz and feldspar, quartz films at the feldspar interface and by albite rims around plagioclase. Some selected samples were analysed for major, minor and trace element content. The leucosomes are characterized by the following major elements content: SiO2: 72.9-76.2; Al2O3: 14.7-15.4; Fe2O3tot: 0.1-0.7; MgO: 0.1-0.3; CaO: 0.5-3.2; Na2O: 2.4-3.5; K2O: 4.0-8.6 wt%. The noticeable wide range in CaO and K2O is related to the high variability of the plagioclase/K-feldspar ratio. Most leucosomes have granitic composition, except for those occurring along shear zones that have tonalitic composition. Mesosomes major elements contents are SiO2 ca. 70; Al2O3: 14.4-15.1; Fe2O3tot: 2.1-3.4; MgO ca. 1.0; CaO ca. 3.0; Na2O ca. 3.5; K2O ca. 2.6 wt.%. They have granodioritic compositions. All leucosome and mesosome samples are corundum normative. Chondrite-normalized REE patterns of leucosomes are characterized by a marked positive Eu anomaly and by LREE enrichment. Mesosomes are characterized by marked negative Eu anomalies, as well as by LREE and HREE enrichment. ?REE is higher in mesosomes (153 ppm) than in leucosomes (20-63 ppm). Field relationships, microstructural and geochemical data support the hypothesis that migmatization was generated by partial melting of a probaby Ordovician granitoid. The origin of the various types of leucosome has been discussed.

  7. The Transport of Heavy Metals by the Mississippi River and Their Fate in the Gulf of Mexico 

    E-print Network

    Trefry, John Harold

    1977-01-01

    . Average Si02, AI2O3 and K2O concentrations in Mississippi River particulates are similar to crustal abundances. Particulate Na20, CaO and MgO values are 60-80% below crustal levels; however a high river dissolved load of these elements offsets the low...

  8. The Transport of Heavy Metals by the Mississippi River and Their Fate in the Gulf of Mexico

    E-print Network

    Trefry, John Harold

    1977-01-01

    . Average Si02, AI2O3 and K2O concentrations in Mississippi River particulates are similar to crustal abundances. Particulate Na20, CaO and MgO values are 60-80% below crustal levels; however a high river dissolved load of these elements offsets the low...

  9. Phase equilibria and crystal chemistry of the CaO–1/2 Nd{sub 2}O{sub 3}–CoO{sub z} system at 885 °C in air

    SciTech Connect

    Wong-Ng, W., E-mail: winnie.wong-ng@nist.gov [Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Laws, W. [Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Talley, K.R. [Department of Materials Science and Engineering, Boise State University, Boise, ID 83725 (United States); Huang, Q. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Yan, Y.; Martin, J. [Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Kaduk, J.A. [Department of Biological and Chemical Sciences, Illinois Institute of Technology, Chicago, IL 60616 (United States)

    2014-07-01

    The phase diagram of the CaO–1/2 Nd{sub 2}O{sub 3}–CoO{sub z} system at 885 °C in air has been determined. The system consists of two calcium cobaltate compounds that have promising thermoelectric properties, namely, the 2D thermoelectric oxide solid solution, (Ca{sub 3?x}Nd{sub x})Co{sub 4}O{sub 9?z} (0?x?0.5), which has a misfit layered structure, and Ca{sub 3}Co{sub 2}O{sub 6} which consists of 1D chains of alternating CoO{sub 6} trigonal prisms and CoO{sub 6} octahedra. Ca{sub 3}Co{sub 2}O{sub 6} was found to be a point compound without the substitution of Nd on the Ca site. The reported Nd{sub 2}CoO{sub 4} phase was not observed at 885 °C. A ternary (Ca{sub 1?x}Nd{sub 1+x})CoO{sub 4?z} (x=0) phase, or (CaNdCo)O{sub 4?z}, was found to be stable at this temperature. A solid solution region of distorted perovskite (Nd{sub 1?x}Ca{sub x})CoO{sub 3?z} (0?x?0.25, space group Pnma) was established. In the peripheral binary systems, while a solid solution region was identified for (Nd{sub 1?x}Ca{sub x}){sub 2}O{sub 3?z} (0?x?0.2), Nd was not found to substitute in the Ca site of CaO. Six solid solution tie-line regions and six three-phase regions were determined in the CaO–Nd{sub 2}O{sub 3}–CoO{sub z} system in air. - Graphical abstract: Phase diagram of the 1/2 Nd{sub 2}O{sub 3}–CaO–CoO{sub x} system at 885 °C, showing the limits of various solid solutions, and the tie-line relationships of various phases. - Highlights: • Phase diagram of the CaO–1/2 Nd{sub 2}O{sub 3}–CoO{sub z} system constructed. • System consists of thermoelectric oxide (Ca{sub 3?x}Nd{sub x})Co{sub 4}O{sub 9?z} (0?x?0.5). • Structures of (Nd{sub 1?x}Ca{sub x})CoO{sub 3?z} and (CaNdCo)O{sub 4?z} determined.

  10. Natural weathering in dry disposed ash dump: Insight from chemical, mineralogical and geochemical analysis of fresh and unsaturated drilled cores.

    PubMed

    Akinyemi, S A; Akinlua, A; Gitari, W M; Khuse, N; Eze, P; Akinyeye, R O; Petrik, L F

    2012-07-15

    Some existing alternative applications of coal fly ash such as cement manufacturing; road construction; landfill; and concrete and waste stabilisation use fresh ash directly collected from coal-fired power generating stations. Thus, if the rate of usage continues, the demand for fresh ash for various applications will exceed supply and use of weathered dry disposed ash will become necessary alternative. As a result it's imperative to understand the chemistry and pH behaviour of some metals inherent in dry disposed fly ash. The bulk chemical composition as determined by XRF analysis showed that SiO2, Al2O3 and Fe2O3 were the major oxides in fresh ash and unsaturated weathered ashes. The unsaturated weathered ashes are relatively depleted in CaO, Fe2O3, TiO2, SiO2, Na2O and P2O5 due to dissolution and hydrolysis caused by chemical interaction with ingressing CO2 from the atmosphere and infiltrating rain water. Observed accumulations of Fe2O3, TiO2, CaO, K2O, Na2O and SO3 and Zn, Zr, Sr, Pb, Ni, Cr and Co in the lower layers indicate progressive downward movement through the ash dump though at a slow rate. The bulk mineralogy of unsaturated weathered dry disposed ash, as determined by XRD analysis, revealed quartz and mullite as the major crystalline phases; while anorthite, hematite, enstatite, lime, calcite, and mica were present as minor mineral phases. Pore water chemistry revealed a low concentration of readily soluble metals in unsaturated weathered ashes in comparison with fresh ash, which shows high leachability. This suggests that over time the precipitation of transient minor secondary mineral phases; such as calcite and mica might retard residual metal release from unsaturated weathered ash. Chloride and sulphate species of the water soluble extracts of weathered ash are at equilibrium with Na+ and K+; these demonstrate progressive leaching over time and become supersaturated at the base of unsaturated weathered ash. This suggests that the ash dump does not encapsulate the salt or act as a sustainable salt sink due to over time reduction in pore water pH. The leaching behaviours of Ca, Mg, Na+, K+, Se, Cr and Sr are controlled by the pH of the leachant in both fresh and unsaturated weathered ash. Other trace metals like As, Mo and Pb showed amphoteric behaviour with respect to the pH of the leachant. The precipitation of minor quantities of secondary mineral phases in the unsaturated weathered ash has significant effects on the acid susceptibility and leaching patterns of chemical species in comparison with fresh ash. The unsaturated weathered ash had lower buffering capacity at neutral pH (7.94-8.00) compared to fresh (unweathered) ash. This may be due to the initial high leaching/flushing of soluble basic buffering constituents from fly ash after disposal. The overall results of the acid susceptibility tests suggest that both fresh ash and unsaturated weathered ash would release a large percentage of their chemical species when in contact with slightly acidified rain. Proper management of ash dumps is therefore essential to safeguard the environmental risks of water percolation in different fly ashes behaviour. PMID:22446137

  11. Condensation in dust-enriched systems

    NASA Astrophysics Data System (ADS)

    Ebel, Denton S.; Grossman, Lawrence

    2000-01-01

    Full equilibrium calculations of the sequence of condensation of the elements from cosmic gases made by total vaporization of dust-enriched systems were performed in order to investigate the oxidation state of the resulting condensates. The computations included 23 elements and 374 gas species, and were done over a range of Ptot from 10 -3 to 10 -6 bar and for enrichments up to 1000× in dust of Cl composition relative to a system of solar composition. Because liquids are stable condensates in dust-enriched systems, the MELTS nonideal solution model for silicate liquids (Ghiorso and Sack, 1995) was incorporated into the computer code. Condensation at 10 -3 bar and dust enrichments of 100×, 500×, and 1000× occur at oxygen fugacities of IW-3.1, IW-1.7, and IW-1.2, respectively, and, at the temperature of cessation of direct condensation of olivine from the vapor, yields XFa of 0.019, 0.088, and 0.164, respectively. Silicate liquid is a stable condensate at dust enrichments >˜12.5× at 10 -3 bar and >˜425× at 10 -6 bar. At 500×, the liquid field is >1000 K wide and accounts for a maximum of 48% of the silicon at 10 -3 bar, and is 240 K wide and accounts for 25% of the silicon at 10 -6 bar. At the temperature of disappearance of liquid, XFa of coexisting olivine is 0.025, 0.14, and 0.31 at 100×, 500×, and 1000×, respectively, almost independent of Ptot. At 1000×, the Na 2O and K 2O contents of the last liquid reach 10.1 and 1.3 wt.%, respectively, at 10 -3 bar but are both negligible at 10 -6 bar. At 10 -3 bar, iron sulfide liquids are stable condensates at dust enrichments at least as low as 500× and coexist with silicate liquid at 1000×. No sulfide liquid is found at 10 -6 bar. At 10 -3 bar, the predicted distribution of Fe between metal, silicate and sulfide at 1310 K and a dust enrichment of 560× matches that found in H-group chondrites, and at 1330 K and 675× matches that of L-group chondrites prior to metal loss. Only at combinations of high Ptot and high dust enrichment do the bulk chemical composition trends of condensates reach the FeO contents typical of type IIA chondrules at temperatures where dust and gas could be expected to equilibrate, ?1200 K. Even under these conditions, however, the composition trajectories of predicted condensates pass through compositions with much more CaO + Al 2O 3 relative to MgO + SiO 2 than those of most type IA chondrules. Furthermore, on a plot of wt.% Na 2O vs. wt.% FeO, most chondrule compositions are too Na 2O-rich to lie along trends predicted for the bulk chemical compositions of the condensates at Ptot ? 10 -3 bar and dust enrichments ?1000×. Together, these chemical differences indicate that individual chondrules formed neither by quenching samples of the liquid + solid condensates that existed at various temperatures nor by quenching secondary liquids that formed from such samples. With the exception of very FeO-poor, Na 2O-rich glasses in type I chondrules and glasses with very high FeO and Na 2O in type II chondrules, however, many chondrule glass compositions fall along bulk composition trajectories for liquids in equilibrium with cosmic gases at 10 -3 bar and dust enrichments between 600× and 1000×. If these chondrules formed by secondary melting of mixtures of condensates that formed at different temperatures, nebular regions with characteristics such as these would have been necessary to prevent loss of Na 2O by evaporation and FeO by reduction from the liquid precursors of their glasses, assuming that the liquids were hot for a long enough time to have equilibrated with the gas.

  12. Multi-component diffusion between molten SiO2 inclusions and surrounding felsic melt in an indochinite: Tektites as natural laboratories

    NASA Astrophysics Data System (ADS)

    Macris, C. A.; Eiler, J. M.; Asimow, P. D.; Stolper, E. M.

    2013-12-01

    Tektites are natural glasses thought to have formed as a result of melting and quenching of distally ejected terrestrial material upon hypervelocity (>11 km/s) impact on Earth. Some tektites contain inclusions of lechatelierite (nearly pure SiO2 glass; 99-100 wt. % SiO2), generally thought to be the amorphous relicts of partially digested quartz grains (Koeberl, 1994). Electron and ion microprobe analyses of major and minor elements were performed on transects between lechatelierite inclusions and the surrounding felsic glass in an indochinite (sample from Newman et al., 1995). The surrounding glass is peraluminous with an average composition of 73.4 wt.% SiO2, 12.8 wt.% Al2O3, 4.5 wt. % FeO, 2.3 wt.% K2O, and < 2 wt.% (each) CaO, MgO, Na2O, and TiO2. The boundary between the lechatelierite and felsic glass is broad (~30 ?m), with complex concentration profiles reflecting diffusion between the two melts at high temperatures (>2200 °C for formation of lechatelierite; Bunch et al., 2012) prior to quenching. Although all components except SiO2 are pinned to near zero at the same point at the lechatelierite end of the profiles, the shapes of the oxide concentration profiles differ, with Ca and Mg falling off from their far-field values first, followed in order by Fe, Ti, Al, Na, and K. K has apparently propagated the longest distance, diffusing faster than other components from the surrounding melt toward the lechatelierite. Furthermore, concentration profiles of K2O systematically increase, reach a maximum, then decrease closest to lechatelierite, indicating uphill diffusion of K against its concentration gradient. All concentration profiles are asymmetric, becoming steepest towards the most silicic portions of the interdiffusion zone approaching lechatelierite, likely due to the sharp compositional contrast between matrix glass and inclusions. Sato (1974) observed similar alkali enrichment in coronas around quartz xenocrysts in basalt and andesite, where K, and to a lesser degree Na, diffused against their concentration gradients. The uphill diffusion of alkalis in corona glass surrounding quartz was interpreted by Sato (1974) with a diffusion model assuming non-ideality of alkali elements in silicate melt, in which diffusion occurs according to the chemical potential gradient of each species. Preliminary calculations using the MELTS (Ghiorso and Sack, 1995) activity-composition model to transform the composition profiles across lechatelierite and felsic glass into chemical potential profiles (at 2200 °C) indicate that all components, including K2O, diffuse down their own chemical potential gradients. We will investigate these phenomena further in attempt to model the observed profiles. A deeper understanding of this problem may inform the factors controlling diffusion coefficients in silicate melts derived from crustal material, as well as the thermal histories of tektites. Bunch T.E. et al. (2012) P NATL ACAD SCI 109:1903-1912 Ghiorso M.S., Sack R.O. (1995) CONTRIB MINERAL PETR 119:197-212 Koeberl C. (1994) GEOL S AM S 133-151 Newman S. et al. (1995) LPS XXVI 26:1039-1040 Sato H. (1974) CONTRIB MINERAL PETROL 50:49-64

  13. Photoluminescence of Eu3+-, Tb3+-, Dy3+- and Tm3+-doped transparent GeO2 TiO2 K2O glass ceramics

    Microsoft Academic Search

    G. Lakshminarayana; Jianrong Qiu; M. G. Brik; I. V. Kityk

    2008-01-01

    In this paper, we present the photoluminescence properties of Eu3+-, Tb3+-, Dy3+- and Tm3+-doped potassium-titanium-germanate glasses and glass ceramics. Following the x-ray diffraction measurement, the glass structure was established. Compared to Eu3+-, Tb3+-, Dy3+- and Tm3+-doped glasses, their respective glass ceramics show stronger emissions due to the presence of the K2TiGe3O9 crystalline phase. For Eu3+-doped glass and glass ceramics, five

  14. SiO 2 -CaO-K 2 O coatings on alumina and Ti6Al4V substrates for biomedical applications

    Microsoft Academic Search

    C. Vitale-Brovarone; E. Verné

    2005-01-01

    Alumina and Ti6Al4V alloys are widely used for orthopedics and dental applications due to their good mechanical properties and biocompatibility. Unfortunately they can not provide a satisfactory osteointegration when implanted. In fact, both alumina and Ti6Al4V are not bioactive and thus they can only guarantee a morphological fixation with the surrounding tissues without a suitable chemical anchorage. Aiming to impart

  15. High-pressure x-ray diffraction studies of the nanostructured transparent vitroceramic medium K2O-SiO2-Ga2O3

    E-print Network

    Kruger, Michael - Department of Physics, University of Missouri

    . Gogol4 1 Department of Physics, University of Missouri--Kansas City, Kansas City, Missouri 64110, USA 2-ku, Tokyo 169-8555, Japan 3 Department of Geosciences, University of Missouri--Kansas City, Kansas City, Missouri 64110, USA 4 School of Biological Sciences, University of Missouri--Kansas City, Kansas City

  16. Properties of CoO doped in Glasses Prepared from Rice Hush Fly Ash in Thailand

    Microsoft Academic Search

    Y. Ruangtaweep; J. Kaewkhao; K. Kirdsiri; C. Kedkaew; P. Limsuwan

    2011-01-01

    In this work, properties of glass from local rice husk ash (RHA) in Thailand have been investigated. RHA was sintered in different temperature. Compositions and phases of RHA were analyzed by energy dispersive x-ray fluorescence spectrometer (EDXRF) and X-ray diffractometer (XRD). The glasses were melt from RHA in formula 20 Na2O : 1.0 Al2O3 : 13 B2O3 : 6.3 CaO

  17. Polylactic acid–phosphate glass composite foams as scaffolds for bone tissue engineering

    Microsoft Academic Search

    G. Georgiou; L. Mathieu; D. P. Pioletti; P.-E. Bourban; J.-A. E. Månson; J. C. Knowles; S. N. Nazhat

    2007-01-01

    Phosphate glass (PG) of the composition 0.46(CaO)- 0.04(Na2O)- 0.5(P2O5) was used as filler in poly-L-lactic acid (PLA) foams developed as degradable scaffolds for bone tissue engineering. The effect of PG on PLA was assessed both in bulk and porous composite foams. Composites with various PG content (0, 5, 10, and 20 wt %) were melt-extruded, and either compression-molded or foamed

  18. Compositional dependence of in-vitro bioactivity in sodium calcium borate glasses

    Microsoft Academic Search

    Manupriya; K. S. Thind; K. Singh; V. Kumar; G. Sharma; D. Singh

    2009-01-01

    Borate glasses with composition xCaO (100?x) B2O3 (20?x?50), where x is in mole percent) and 50CaO·45B2O3·5Na2O have been prepared using conventional melt quench technique. Samples were submerged in simulating body fluid solution (SBF) at 37°C for various periods of time. After storage the samples were analyzed in order to investigate if a surface layer of hydroxyl carbonate apatite layer (HCA

  19. HiRes/MIA Measurements of EAS Development Between and eV T.Abu-Zayyad, K.Belov, D.J.Bird , J.Boyer , Z.Cao, M.Catanese, G.F.Chen, R.W.Clay , C.E.Covault,

    E-print Network

    .Belov¾, D.J.Bird , J.Boyer , Z.Cao¾, M.Catanese¿, G.F.Chen¾, R.W.Clay , C.E.Covault½, J.W.Cronin½, H.D.Green½, Y.Ho , A.Huang¾, C.C. Jui¾, M.J.Kidd , D.B.Kieda¾, B.C.Knapp , S.Ko¾, C.G.Larsen¾, W.Lee , E

  20. Search for solid conductors of Na/+/ and K/+/ ions - Five new conductors

    NASA Technical Reports Server (NTRS)

    Singer, J.; Kautz, H.; Fielder, W.; Fordyce, J.

    1975-01-01

    Five new conductors of positive Na and K ions, for use as separators in high energy secondary batteries, have been discovered. They include: (1) the pyrochlores NaTaWO6 and NaTa2O5F; (2) the bcc form of NaSbO3; and (3) the niobates 2Na2O-3Nb2O5 and 2K2O-3Nb2O5, with the alkali ions probably in open layers of the completely determined structure. On the basis of approximately 40 structure types, generalizations have been made regarding the relation between structure and ionic transport.

  1. Development of glass–ceramic scaffolds for bone tissue engineering: Characterisation, proliferation of human osteoblasts and nodule formation

    Microsoft Academic Search

    C. Vitale-Brovarone; E. Verné; L. Robiglio; P. Appendino; F. Bassi; G. Martinasso; G. Muzio; R. Canuto

    2007-01-01

    Glass–ceramic macroporous scaffolds for tissue engineering have been developed using a polyurethane sponge template and bioactive glass powders. The starting glass (CEL2) belongs to the system SiO2–P2O5–CaO–MgO–Na2O–K2O and has been synthesised by a conventional melting–quenching route. A slurry of CEL2 powder, polyvinyl alcohol and water has been prepared in order to coat, by impregnation, the polymeric template. An optimised thermal

  2. Bioactive borosilicate glass scaffolds: improvement on the strength of glass-based scaffolds for tissue engineering

    Microsoft Academic Search

    Xin Liu; Wenhai Huang; Hailuo Fu; Aihua Yao; Deping Wang; Haobo Pan; William W. Lu

    2009-01-01

    Three-dimensional macroporous scaffolds with the pore size of 200–500 ?m were fabricated by replication method using bioactive\\u000a borosilicate glass from Na2O–K2O–MgO–CaO–SiO2–P2O5–B2O3 system. The effects of the strength of the strut in reticulated scaffold, as well as the geometrical parameter of the scaffold\\u000a on the strength of reticulated scaffold were investigated. Scanning electron microscope (SEM) and X-ray diffraction (XRD)\\u000a results show that

  3. Feasibility, tailoring and properties of polyurethane\\/bioactive glass composite scaffolds for tissue engineering

    Microsoft Academic Search

    Francesco Baino; Enrica Verné; Chiara Vitale-Brovarone

    2009-01-01

    This research work aims to propose highly porous polymer\\/bioactive glass composites as potential scaffolds for hard-tissue\\u000a and soft-tissue engineering. The scaffolds were prepared by impregnating an open-cells polyurethane sponge with melt-derived\\u000a particles of a bioactive glass belonging to the SiO2–P2O5–CaO–MgO–Na2O–K2O system (CEL2). Both the starting materials and the composite scaffolds were investigated from a morphological and structural\\u000a viewpoint by X-ray

  4. Electrical properties of R 2 O–Al 2 O 3 –SiO 2 glass–ceramics for anodic bonding

    Microsoft Academic Search

    Dehua XiongHong; Hong Li; Jinshu Cheng

    2010-01-01

    Temperature and frequency dependence on electrical properties (dielectric constant, dielectric loss and conductivity) of Li2O–Na2O–K2O–Al2O3–SiO2(R2O–Al2O3–SiO2) system glass–ceramics used as anodic bonding materials were discussed. The results showed that the main crystal phase of\\u000a glass–ceramics was lithium metasilicate (Li2SiO3). Compared with the parent glass, both the dielectric constant and dielectric loss of glass–ceramics decreased, the dielectric\\u000a constant and dielectric loss increased

  5. In vitro behavior of silicate glass coatings on Ti6Al4V

    Microsoft Academic Search

    Eduardo Saiz; Marni Goldman; Jose M. Gomez-Vega; Antoni P. Tomsia; Grayson W. Marshall; Sally J. Marshall

    2002-01-01

    The in vitro response in simulated body fluid (SBF) of silicate glass coatings on Ti6Al4V was evaluated. Glasses belonging to the SiO2–CaO–MgO–Na2O–K2O–P2O5 system were used to prepare 50–70?m thick coatings on Ti6Al4V, employing a simple enameling technique. Glasses with silica content higher than 55wt% can be used to prepare coatings that do not crack or delaminate and exhibit good adhesion

  6. Deciphering the source and contamination history of peraluminous magmas using ? 18 O of accessory minerals: examples from garnet-bearing plutons of the Sierra Nevada batholith

    Microsoft Academic Search

    Jade Star Lackey; John W. Valley; Hans J. Hinke

    2006-01-01

    Peraluminous granitoids provide critical insight as to the amount and kinds of supracrustal material recycled in the central\\u000a Sierra Nevada batholith, California. Major element concentrations indicate Sierran peraluminous granitoids are high-SiO2 (68.9–76.9) and slightly peraluminous (average molar Al2O3\\/(CaO + Na2O + K2O)=1.06). Both major and trace element trends mimic those of other high-silica Sierran plutons. Garnet (Grt) in the peraluminous\\u000a plutons is almandine–spessartine-rich and

  7. Geochemistry and petrology of Tertiary volcanic rocks and related ultramafic xenoliths from the central and eastern Oman Mountains

    Microsoft Academic Search

    Sobhi Nasir; Abdulrazak Al-Sayigh; Abdulrahman Alharthy; Ali Al-Lazki

    2006-01-01

    The Tertiary volcanic rocks of the central and the eastern parts of the Oman Mountains consist mainly of basanites with abundant upper mantle ultramafic xenoliths. The lavas are alkaline (42–43 wt.% SiO2; 3.5–5.5 wt.% Na2O+K2O). They include primitive (11–14 wt.% MgO) features with strong OIB-like geochemical signatures. Trace element and Sr–Nd isotope data for the basanites suggest mixing of melts derived from variable

  8. Bulk, rare earth, and other trace elements in Apollo 14 and 15 and Luna 16 samples.

    NASA Technical Reports Server (NTRS)

    Laul, J. C.; Wakita, H.; Showalter, D. L.; Boynton, W. V.; Schmitt, R. A.

    1972-01-01

    Measurement of 24 and 34 bulk, minor, and trace elements in lunar specimens by instrumental and radiochemical neutron activation analysis shows greater Al2O3, Na2O, and K2O abundances and higher TiO2, FeO, MnO and Cr2O3 depletions in Apollo 14 soil samples as compared to Apollo 11 samples and to most of Apollo 12 samples. The uniform abundances in 14230 core tube soils and three other Apollo 14 soils indicate that the regolith is uniform to at least 22 cm depth and within about 200 m from the lunar module.

  9. Triassic Nb-enriched basalts, magnesian andesites, and adakites of the Qiangtang terrane (Central Tibet): evidence for metasomatism by slab-derived melts in the mantle wedge

    Microsoft Academic Search

    Qiang Wang; Derek A. Wyman; Jifeng Xu; Yusheng Wan; Chaofeng Li; Feng Zi; Ziqi Jiang; Huaning Qiu; Zhuyin Chu; Zhenhua Zhao; Yanhui Dong

    2008-01-01

    New chronological, geochemical, and isotopic data are reported for Triassic (219–236 Ma) adakite-magnesian andesite-Nb-enriched\\u000a basaltic rock associations from the Tuotuohe area, central Qiangtang terrane. The adakites and magnesian andesites are characterized\\u000a by high Sr\\/Y (25–45), La\\/Yb (14–42) and Na2O\\/K2O (12–49) ratios, high Al2O3 (15.34–18.28 wt%) and moderate to high Sr concentrations (220–498 ppm) and ?ND (t) (+0.86 to +1.21) values. Low enrichments

  10. Late Cretaceous high?K volcanism in the eastern Pontide orogenic belt: implications for the geodynamic evolution of NE Turkey

    Microsoft Academic Search

    Yener Eyübo?lu

    2010-01-01

    High?K volcanics were produced in two different Late Cretaceous cycles during the infilling of back?arc basins of the eastern Pontides. The first cycle, represented by shoshonitic trachyandesites and associated pyroclastics, containing high K2O (2.74–4.81 wt?%) and Na2O (3.60–5.51 wt?%), overlies a mid?Cretaceous ophiolitic?olistostromal melange formed during the rifting stage of a back?arc basin (Neotethys). Ar\\/Ar dating of biotite from trachyandesite

  11. Origin of hydrous fluids at seismogenic depth: Constraints from natural and experimental fault rocks

    NASA Astrophysics Data System (ADS)

    Mittempergher, Silvia; Dallai, Luigi; Pennacchioni, Giorgio; Renard, François; Di Toro, Giulio

    2014-01-01

    Fluids control the mechanical behavior of fault zones during the seismic cycle. We used geochemical, mineralogical, microstructural, hydrogen isotope compositions and Fourier Transform Infrared (FTIR) investigations to characterize the origin of hydrous fluids involved in ductile and brittle shear zones at the bottom of the seismogenic crust. Natural samples were collected from exhumed mylonitic shear zones and cataclasite-pseudotachylyte bearing faults in the northern Adamello (Italian Southern Alps), which were active at 9-11 km depth. Pseudotachylytes, solidified coseismic friction-induced melts, testify to ancient seismogenic behavior of the faults. Natural pseudotachylytes were compared with artificial pseudotachylytes produced in high velocity friction experiments simulating seismic slip. Mylonites have mineralogical, elemental and hydrogen isotope compositions (-80‰K2O, Ba, Rb; depletion in CaO, Na2O, SiO2) and hydrogen isotope (-69‰50 °C and have low ?D value (-93‰). The hydrogen isotope composition of bulk samples is dominated by the composition of cryptocrystalline domains (-103‰

  12. Formation and emplacement of two contrasting late-Mesoproterozoic magma types in the central Namaqua Metamorphic Complex (South Africa, Namibia): Evidence from geochemistry and geochronology

    NASA Astrophysics Data System (ADS)

    Bial, Julia; Büttner, Steffen H.; Frei, Dirk

    2015-05-01

    The Namaqua Metamorphic Complex is a Mesoproterozoic low-pressure, granulite facies belt along the southern and western margin of the Kaapvaal Craton. The NMC has formed between ~ 1.3 and 1.0 Ga and its central part consists essentially of different types of granitoids intercalated with metapelites and calc-silicate rocks. The granitoids can be subdivided into three major groups: (i) mesocratic granitoids, (ii) leucocratic granitoids and (iii) leucogranites. The high-K, ferroan mesocratic granitoids (54-75 wt% SiO2) have a variable composition ranging from granitic to tonalitic, and contain biotite and/or hornblende or orthopyroxene. They are strongly enriched in REE and LILE, indicating A-type chemical characteristics, and are depleted in Ba, Sr, Eu, Nb, Ta and Ti. The leucocratic granitoids and leucogranites (68-76 wt% SiO2) differ from the other group in having a granitic or slightly syenitic composition containing biotite and/or garnet/sillimanite. They have lower REE and MgO, FeOt, CaO, TiO2, MnO concentrations, but higher Na2O and K2O contents. Compositional variations in mesocratic granitoids indicate their formation by fractional crystallization of a mafic parental magma. Leucocratic granitoids and leucogranites lack such trends, which suggests melting of a felsic crustal source without subsequent further evolution of the generated magmas. The mineralogical and geochemical characteristics of the mesocratic granitoids are consistent magmatic differentiation of a mantle derived, hot (> 900 °C) parental magma. The leucocratic granitoids and leucogranites granites were formed from low-temperature magmas (< 730 °C), generated during fluid-present melting from metasedimentary sources. New U-Pb zircon ages reveal that both magma types were emplaced into the lower crust within a 30-40 million years interval between 1220-1180 Ma. In this time period the crust reached its thermal peak, which led to the formation of the leucocratic granitoids and leucogranites. A prolonged period of relatively high crustal temperatures is followed by a second heat pulse at ~ 1100 Ma, that was intense enough to facilitate zircon growth in the older plutons and it produced a younger granite suite. The crust cools down below amphibolite facies conditions after a further 100 million years. The prolonged high-temperature history is best compatible with steady and long-lasting heat transfer from mantle sources, suggesting a continental back-arc situation as the most likely setting of the NMC in the late Mesoproterozoic.

  13. Mg and Fe-rich carbonate-silicate high-density fluids in cuboid diamonds from the Internationalnaya kimberlite pipe (Yakutia)

    NASA Astrophysics Data System (ADS)

    Zedgenizov, D. A.; Ragozin, A. L.; Shatsky, V. S.; Araujo, D.; Griffin, W. L.; Kagi, H.

    2009-11-01

    Microinclusions in 44 cuboid diamonds from the Internationalnaya kimberlite pipe (Yakutia) show wide compositional variations. In comparison with the available worldwide database most microinclusions in diamonds from Internationalnaya define a continuous range of compositions from carbonatitic to hydrous-silicic high-density fluids (HDFs). The hydrous-silicic compositional range is reported here for the first time in Yakutian diamond-forming fluids. The hydrous-silicic end-members are rich in water, SiO 2, Al 2O 3, K 2O and P 2O 5. Carbonatitic end-members are rich in carbonate, CaO, MgO, Na 2O and FeO. Microinclusions in diamonds from Internationalnaya show a range from magnesian to extremely iron-rich compositions. There are two compositional arrays of microinclusions: (i) carbonate-rich with SiO 2 < 10 wt.% where FeO decreases without any correlation with sulfur, water, carbonate or chlorine and (ii) carbonatitic to hydrous-silicic where FeO generally decreases as SiO 2 contents increase. The trace-element patterns of the microinclusions are generally similar to those of kimberlites and carbonatites, but there are significant differences in the major elements. The relative abundance of K in the microinclusions is significantly higher. The microinclusions have smooth patterns for the LILE, normalized to a primitive mantle composition. HFSE patterns in the microinclusions show some depletion in Ti, Zr and Hf relative to Ta, Nb and Mo. Primitive mantle normalized REE patterns reveal low abundances of the heavy REE and high concentrations of light REE. The La/Dy ratio of microinclusions varies widely, decreasing from carbonatitic to hydrous-silicic compositions. A general correlation of ? 13C of diamonds with the relative abundance of carbonates in the microinclusions suggests that carbon isotope compositions are related to the evolution of the parental media. The carbonate-silicate range of high-density fluids observed in diamonds from Internationalnaya may be explained by fractional crystallization of mantle fluids/melts, or mixing between liquids with different compositions.

  14. Aklimaite, Ca4[Si2O5(OH)2](OH)4 · 5H2O, a new natural hydrosilicate from Mount Lakargi, the Northern Caucasus, Russia

    NASA Astrophysics Data System (ADS)

    Zadov, A. E.; Pekov, I. V.; Zubkova, N. V.; Gazeev, V. M.; Chukanov, N. V.; Yapaskurt, V. O.; Kartasheov, P. M.; Galuskin, E. V.; Galuskina, I. O.; Pertsev, N. N.; Gurbanov, A. G.; Pushcharovsky, D. Yu.

    2013-12-01

    A new mineral aklimaite, Ca4[Si2O5(OH)2](OH)4 · 5H2O, has been found near Mount Lakargi, Upper Chegem caldera, Kabardino-Balkaria, the Northern Caucasus, Russia, in the skarnified limestone xenolith in ignimbrite. This hydrothermal mineral occurs in a cavity of altered larnite skarn and is associated with larnite, calcium humite-group members, hydrogarnets, bultfonteinite, afwillite, and ettringite. Aklimaite forms transparent, colorless (or occasionally with pinkish tint) columnar or lath-shaped crystals up 3 × 0.1 × 0.01 mm in size, flattened on {001} and elongated along {010}; they are combined in spherulites. The luster is vitreous; the cleavage parallel to the {001} is perfect. D calc = 2.274 g/cm3. The Mohs' hardness is 3-4. Aklimaite is optically biaxial, negative, 2 V meas > 70°, 2 V calc = 78°, ? = 1.548(2), ? = 1.551(3), ? = 1.553(2). The IR and Raman spectra are given. The chemical composition (wt %, electron microprobe) is as follows: 0.06 Na2O, 0.02 K2O, 45.39 CaO, 0.01 MnO, 0.02 FeO, 24.23 SiO2, 0.04 SO3, 3.22 F, 27.40 H2O(calc.), -1.36 -O=F2; the total is 99.03. The empirical formula calculated on the basis of 2Si apfu with O + OH + F = 16 is as follows: (Ca4.02Na0.01)?4.03[Si2.00O5.07(OH)1.93][(OH)3.16F0.84] ?4.00 · 5H2O. The mineral is monoclinic, space group C2/ m, a = 16.907(5), b = 3.6528(8), c = 13.068(4) Å, ? = 117.25(4)·, V= 717.5(4) Å3, Z = 2. Aklimaite is representative of the new structural type, the sorosilicate with disilicate groups [Si2O5(OH)2]. The strongest reflections in the X-ray powder patterns [ d, Å ( hkl)] are: 11.64(100)(001), 2.948(32)(310, 203), 3.073(20) (, ), 2.320(12)(005, 510), 2.901 (11)(004), 8.30(10). The type specimen is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.

  15. Osumilite-(Mg): Validation as a mineral species and new data

    NASA Astrophysics Data System (ADS)

    Chukanov, N. V.; Pekov, I. V.; Rastsvetaeva, R. K.; Aksenov, S. M.; Belakovskiy, D. I.; Van, K. V.; Schüller, W.; Ternes, B.

    2013-12-01

    Osumilite-(Mg), the Mg-dominant analogue of osumilite, has been approved by the CNMNC IMA as a new mineral species. The holotype sample has been found at Bellerberg, Eifel volcanic area, Germany. Fluorophlogopite, sanidine, cordierite, mullite, sillimanite, topaz, pseudobrookite and hematite are associated minerals. Osumilite-(Mg) occurs as short prismatic or thick tabular hexagonal crystals reaching 0.5 × 1 mm in size in the cavities in basaltic volcanic glasses at their contact with thermally metamorphosed xenoliths of pelitic rocks. The mineral is brittle, with Mohs' hardness 6.5. Cleavage was not observed. Color is blue to brown. D meas = 2.59(1), D calc = 2.595 g/cm3. No bands corresponding to H2O and OH-groups are in the IR spectrum. Osumilite-(Mg) is uniaxial (+), ? = 1.539(2), ? = 1.547(2). The chemical composition (electron microprobe, average of 5 point analyses, wt %) is: 0.08 Na2O, 3.41 K2O, 0.04 CaO, 7.98 MgO, 0.28 MnO, 21.57 Al2O3, 3.59 Fe2O3, 62.33 SiO2, total 99.28. The empirical formula is: (K0.72Na0.03Ca0.01)(Mg1.97Mn0.04)[Al4.21Fe{0.45/3+}Si10.32]O30. The simplified formula is: KMg2Al3(Al2Si10)O10. The crystal structure was refined on a single crystal, R = 0.0294. Osumilite-(Mg) is hexagonal, space group P6/ mcc; a = 10.0959(1), c = 14.3282(2)Å, V = 1264.79(6) Å3, Z = 2. The strongest reflections in the X-ray powder diffraction pattern [ d, Å I %) ( hkl)] are: 7.21 (37) (002), 5.064 (85) (110), 4.137 (45) (112), 3.736 (43) (202), 3.234 (100) (211), 2.932 (42) (114), 2.767 (51) (204). A type specimen is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, registration number 4174/1.

  16. Explosive eruption of rhyodacitic magma at the Cordón-Caulle volcanic complex, southern Chile

    NASA Astrophysics Data System (ADS)

    Castro, J. M.; Schipper, C.

    2011-12-01

    After lying dormant for decades, the Cordón-Caulle volcanic complex (CCVC) reactivated again on 4 June, 2011 with an explosive eruption that produced a sustained vertical ash column reaching roughly 14,000 m a.s.l. This explosive phase produced a tephra plume that dispersed E-SE across the Chilean Patagonia into Argentina, and within a week encircled the globe prompting widespread disruption to air traffic and several airport closures. After about 3 weeks of fluctuating explosive activity, a lava flow began effusing from the same vent as the initial activity. We analyzed pumice and ash samples of the Plinian fall from 4 June for their major and trace element makeup, mineralogical characteristics, and 3D textural relationships within pyroclasts. The light beige, phenocryst-poor (<5 vol%) pumice contains plagioclase (~1mm) as its primary phase, and magnetite, orthopyroxene and clinopyroxene in sub-equal amounts. The crystals often form intergrowth clusters but may also be found separate and enclosed in highly vesicular microlite-free glass. As shown by XRF analyses on bulk pumice and ash samples collected from two localities southeast of the vent, the current eruptives comprise the following (in wt.%): SiO2 = 69.6, TiO2 = 0.70, Al2O3 = 14.3, Fe2O3 = 4.56, MnO = 0.11, MgO = 0.54, CaO = 2.3, Na2O = 5.14, K2O = 2.75, P2O5 = 0.11; and, (in ppm): Cr = 6.7, Ni = 2.3, Rb = 70.3, Sr = 163.3, Y = 51.7, Zr = 328, Ba = 702, Pb = 23.7. Interestingly, these compositions are virtually identical to those of magma erupted during 1960 and closely resemble rhyodacite erupted in 1921 from nearby vents. The primary difference between the present eruption and its recent predecessors is the much greater eruptive vigour of the current phase. Another distinction between the present and past historical eruptions is the presence of conspicuous mafic-felsic mingling textures in a small percentage (~0.5 vol%) of the current pumice. Textural and chemical analyses of the mafic blobs are currently underway in order to establish their role in the eruption. The apparent compositional homogeneity of silicic magmas erupted recently at CCVC highlights several important problems regarding magma chamber longevity, eruption triggering, and dynamics of explosive-effusive eruption cycles at CCVC. We are currently addressing some of these topics through further analytical and textural characterization of the eruption products, field relations, and experimental reproduction of salient petrological features.

  17. Alteration of basaltic glass: Mechanisms and significance for the oceanic crust-seawater budget

    NASA Astrophysics Data System (ADS)

    Staudigel, Hubert; Hart, Stanley R.

    1983-03-01

    Alteration of basaltic glass to palagonite is characterized by a nearly isomolar exchange of SiO 2, Al 2O 3, MnO, MgO, CaO, Na 2O, P 2O 5, Zn, Cu, Ni, Cr, Hf, Sc, Co and REE for H 2O and K 2O, whilst TiO 2 and FeO are passively accumulated during removal of the remaining cations. The network forming cations Al and Si are removed from the glass in proportion to the gain in Ti and Fe, whilst the other cations do not show a significant relationship to the amount of Ti and Fe accumulation. Sr isotopic data show that during palagonite formation approximately 85% of the basaltic Sr is lost to the hydrous solutions and 40% of seawater Sr is added to the glass, yielding an average loss of the same order of magnitude as of the network forming cations. Losses and gains of oxides yield an average increase of +105% TiO 2. K, Rb, and Cs show high increases, but K/Rb and K/Cs ratios indicate two different alteration processes: (1) formation of palagonite involves a drastic decrease in these ratios, indicating structural similarities between palagonite and smectite; (2) surface alteration of glass is characterized by an increase in K/Rb and K/Cs ratios, probably best interpreted as sorption of alkalies in ratios approximating those of seawater. The total fluxes involved in alteration of glass in the upper portion of the oceanic crust are estimated from the modal abundance of palagonite in the oceanic crust and the abundance of the vein materials smectite and carbonate. Smectite and carbonates act as a sink for a significant portion of the elements liberated up during alteration of basaltic glass except for Na and Al, which are probably taken up by zeolites and/or albite, possibly hidden in the macroscopic estimate of carbonate. Formation of the observed quantity of secondary phases requires additional sources for Si, Fe. Ca and K. K is provided in excess from the inflowing seawater at reasonable water/rock ratios. The remaining excess Ca, Si and Fe required may be derived by alteration of interstitial glass and breakdown of anorthite rich plagioclase and titano-magnetite, and/or by supply of deeper seated metamorphic reactions.

  18. Geochemistry of oceanic igneous rocks - Ridges, islands, and arcs - With emphasis on manganese, scandium, and vanadium

    USGS Publications Warehouse

    Doe, B.R.

    1997-01-01

    A database on a number of elements in oceanic volcanic rocks is presented, including the principal major-element oxides - SiO2, TiO2, Al2O3, Fe2O3(T), MnO, MgO, CaO, Na2O, K2O, and P2O5 (where T refers to total iron) - and the trace elements - Ba, Ce, Cr, Cu, Ni, Sc, Sr, V, Pb (mainly by isotope dilution), Yb, Zn, and Zr. Interpretations are given for transition metals, with emphasis on Mn, Sc, and V, in order to determine the concentration of the elements in primitive melts and assess their trends in magmatic differentiation. Transition metals are not enriched in plagioclase, so all are incompatible with pure plagioclase removal - that is, they become enriched in the melt. Both Cr and Ni are known to be highly compatible with olivine separation - i.e., they are depleted in the melt early in differentiation. Also, Sc is compatible with clinopyroxene (Cpx) removal from the melt and is depleted by separation of Cpx. Copper does not fit well in any of the principal silicates, but Cu, like Ni, is greatly enriched in sulfides that may remain in the source or separate from the magma. Decreasing Ni abundances and increasing Cu contents during differentiation are a sign of olivine separation. In the analysis presented herein, V - in the absence of Cpx separation - is found to behave remarkably like the moderately incompatible element Zn, and these two elements add to the list of element pairs of similar incompatibility whose ratios are insensitive to differentiation and to submarine weathering as well. Both are enhanced in titanomagnetite, so both would he compatible during titanomagnetite separation. When Cpx separates, however, V becomes compatible like Sc, but Zn remains incompatible. Thus, decreasing V (and Sc) contents and increasing Zn contents during differentiation are a sign of Cpx separation. Manganese often behaves much like Zn and therefore is moderately incompatible, but Mn is less compatible than Zn and V in titanomagnetite. Thus, decreasing Zn and V with increasing Mn is an indication of titanomagnetite removal. Dual compatible and incompatible trends with differentiation are found chiefly for Cu, Sc, and Sr. Distinguishing mid-ocean ridge basalts (MORB), oceanic-island volcanic rocks (OIV), and island-arc volcanic rocks (IAV) may be accomplished by plots of Ce/Yb versus Ba/Ce, where OIV plot to higher values of Ce/Yb than do MORB, and IAV data plot to higher values of Ba/Ce than do those of MORB. These ratios do not seem to be significantly affected by submarine weathering.

  19. Isotopic geochemistry, zircon U-Pb ages and Hf isotopes of A-type granites from the Xitian W-Sn deposit, SE China: Constraints on petrogenesis and tectonic significance

    NASA Astrophysics Data System (ADS)

    Zhou, Yun; Liang, Xinquan; Wu, Shichong; Cai, Yongfeng; Liang, Xirong; Shao, Tongbin; Wang, Ce; Fu, Jiangang; Jiang, Ying

    2015-06-01

    Zircon U-Pb geochronological, geochemical and petrological analyses have been carried out on the Xitian granite emplaced in the middle part of Shi-Hang zone, which is closely related to the economically important Xitian tungsten-tin deposit in Hunan Province, Southeast China. LA-ICP-MS zircon U-Pb dating of two representative samples yielded weighted means 206Pb/238U age of 151.7 ± 1.2 Ma and 151.8 ± 1.4 Ma. These granites are comprised mainly of K-feldspar, quartz, plagioclase, Fe-rich biotite and minor fluorite, and are characterized by enrichments in Rb, Th, REEs (total REE = 159-351 ppm), and HFSEs (e.g., Zr and Y) but depletions in Ba, Sr, P, Eu and Ti. They are metaluminous to weakly peraluminous and show a clear A-type granite geochemical signature with high SiO2 (73.44-78.45 wt.%), total alkalis (Na2O + K2O = 2.89-8.98 wt.%), Fe2O3?/MgO ratios and low P2O5, CaO, MgO and TiO2 contents. In-situ zircon Hf isotope analysis suggests their ?Hf(t) values ranging from -7.43 to -14.69. Sr-Nd isotope data show their ?Nd(t) values in the range of -9.2 to -7.3, with corresponding TDM2 ages of 1.72-1.56 Ga. These characteristics indicate that the Xitian granite originated from partial melting of metamorphic basement rocks with a certain amount of mantle-derived materials. Combined with previous geochemical and isotopic data, it is derived that mantle-crust interaction was gradually enhanced from the early to late stages of magmatism. The ore-forming materials and fluids of the Xitian W-Sn deposit are mainly produced by the Early Yanshanian granitic magmatism, which is also responsible for the Late Jurassic (ca. 152 Ma) A-type granitic rocks that host the W-Sn polymetallic deposits distributed along the Shi-Hang zone, implying a significant Mesozoic extensional event in Southeast China likely caused by the subduction of the Paleo-Pacific plate.

  20. Neogene ignimbrites in the area of Arequipa, southern Peru: correlations, flow directions and sources

    NASA Astrophysics Data System (ADS)

    Paquereau, P.; Thouret, J.-C.; Wörner, G.; Fornari, M.; Roperch, P.

    2003-04-01

    In the area of Arequipa, the ignimbrites termed "sillars" are indurated, more or less welded pyroclastic flow deposits of rhyolitic composition. Our stratigraphic study and Ar-Ar date ages, show four main ignimbrite units: (1) two middle Miocene units (between 13.07±0.05 and 14.8±0.15 Ma) including the "base of Rio Chili" and the "Old sillar"; (2) a Middle to Early Pliocene unit (4.87±0.02 Ma), represented by the "La Joya sillar", (3) two Late Pliocene units (1.64±0.07 Ma), including a "white sillar" which grades into an overlying "pinkish unit", and finally (4) early Pleistocene (1.02±0.09 Ma) pumice-flow deposits channeled in the Rio Yura valley on the west flank of the Chachani volcanic complex. All these units are intercalated with alluvial sediments of variable thickness. The mineral assemblage encompasses plagioclase, biotite, quartz, sanidine, magnetite and ilmenite. Amphibole is only present in the "old sillar" and "La Joya sillar", which are unique in being porphyric. Crystals display large compositional variations because they are weathered. However, the MnO v. FeO diagram for biotites allows us to separate three compositional groups which correspond to (1) the "base of Rio Chili", (2) the Pliocene ignimbrites, and (3) the "old sillar". Harker diagrams of whole rock (pumice) analyses, show two distinct fractional crystallization trends with parallel evolutions. The first trend, which shows an evolution within Miocene ignimbrites, is more enriched in K_2O, Nb, Y and less enriched in Ba, Sr, Na_2O, CaO and P_2O_5 than the second Pliocene trend. We cannot locate source(s) for the Miocene ignimbrites because intense deformation and erosion have taken place after their emplacement; in addition AMS is not a valid method in this case because the flows are channelized in valleys, thus strongly influenced by the paleotopography. The source of the Pliocene ignimbrites, however, can be located by the AMS directions toward the NE of Arequipa depression, probably beneath the Chachani volcanic complex. The Pleistocene "Rio Yura Tuffs" source should be found on the north flank of Chachani, beneath Cerro Nocarani.

  1. Reprint of "Geochemistry and petrogenetic significance of natrocarbonatites at Oldoinyo Lengai, Tanzania: Composition of lavas from 1988 to 2007"

    NASA Astrophysics Data System (ADS)

    Keller, J.; Zaitsev, A. N.

    2012-11-01

    The natrocarbonatites of Oldoinyo Lengai, Tanzania, are unique in magmatic petrology. The historical activity of Oldoinyo Lengai has seen changes from nephelinitic to natrocarbonatitic character of the emitted magmas. Since 1983 the activity was characterized by the effusion of fluid natrocarbonatite lava from which we have collected and analyzed fresh samples in the summit crater from 1988 to 2007. The available compositional data set forms the basis for presenting and discussing the typical composition and variation of natrocarbonatites and their relationship to the silicate magmas of Oldoinyo Lengai. The "type" natrocarbonatite major and trace element composition is derived for an average of 25 samples with low standard deviation. Oldoinyo Lengai carbonatites are unique in almost all aspects of their petrological and geochemical characteristics and are characterized as extremely alkali-rich, with Na2O + K2O generally about 40 wt.%, and with high CaO contents of 14-18 wt.%. This composition results from the presence of phenocrysts of nyerereite (Na,K)2Ca(CO3)2 and gregoryite (Na,K,Cax)2-x(CO3) dominating the highly porphyritic natrocarbonatite lavas, with sylvite and fluorite as main groundmass minerals. The significance of particular trace element concentrations and ratios of equally incompatible elements (REE, Ba, Sr, Th/U, Nb/Ta, Zr/Hf) is evaluated for models of liquid-liquid separation. In defining a "type" natrocarbonatite composition, we also distinguish special variations in chemical and/or mineralogical compositions as follows: (1) silicate-bearing natrocarbonatites, characterized by the occurrence of nephelinite spheroids, as in the 1993 and 2006 lavas; (2) residual melt compositions as described from the 1988 eruptive period as represented by the aphyric, filter-pressed interstitial melt of solidifying porphyritic lavas; (3) an interlude during 2000 when natrocarbonatites with sylvite and fluorite microcrysts were emitted. After 25 years of mostly mild activity characterized by effusion and spattering of fluid natrocarbonatite lava, the paroxysmal ash eruptions of September 4, 2007, changed dramatically the crater morphology, eruptive dynamics and magma composition of Oldoinyo Lengai. Fresh natrocarbonatites — if present at the bottom of the deep crater pit formed during the 2007-2008 explosive activity — will possibly remain inaccessible for decades.

  2. Geochemistry and petrogenetic significance of natrocarbonatites at Oldoinyo Lengai, Tanzania: Composition of lavas from 1988 to 2007

    NASA Astrophysics Data System (ADS)

    Keller, J.; Zaitsev, A. N.

    2012-09-01

    The natrocarbonatites of Oldoinyo Lengai, Tanzania, are unique in magmatic petrology. The historical activity of Oldoinyo Lengai has seen changes from nephelinitic to natrocarbonatitic character of the emitted magmas. Since 1983 the activity was characterized by the effusion of fluid natrocarbonatite lava from which we have collected and analyzed fresh samples in the summit crater from 1988 to 2007. The available compositional data set forms the basis for presenting and discussing the typical composition and variation of natrocarbonatites and their relationship to the silicate magmas of Oldoinyo Lengai. The "type" natrocarbonatite major and trace element composition is derived for an average of 25 samples with low standard deviation. Oldoinyo Lengai carbonatites are unique in almost all aspects of their petrological and geochemical characteristics and are characterized as extremely alkali-rich, with Na2O + K2O generally about 40 wt.%, and with high CaO contents of 14-18 wt.%. This composition results from the presence of phenocrysts of nyerereite (Na,K)2Ca(CO3)2 and gregoryite (Na,K,Cax)2-x(CO3) dominating the highly porphyritic natrocarbonatite lavas, with sylvite and fluorite as main groundmass minerals. The significance of particular trace element concentrations and ratios of equally incompatible elements (REE, Ba, Sr, Th/U, Nb/Ta, Zr/Hf) is evaluated for models of liquid-liquid separation. In defining a "type" natrocarbonatite composition, we also distinguish special variations in chemical and/or mineralogical compositions as follows: (1) silicate-bearing natrocarbonatites, characterized by the occurrence of nephelinite spheroids, as in the 1993 and 2006 lavas; (2) residual melt compositions as described from the 1988 eruptive period as represented by the aphyric, filter-pressed interstitial melt of solidifying porphyritic lavas; (3) an interlude during 2000 when natrocarbonatites with sylvite and fluorite microcrysts were emitted. After 25 years of mostly mild activity characterized by effusion and spattering of fluid natrocarbonatite lava, the paroxysmal ash eruptions of September 4, 2007, changed dramatically the crater morphology, eruptive dynamics and magma composition of Oldoinyo Lengai. Fresh natrocarbonatites — if present at the bottom of the deep crater pit formed during the 2007-2008 explosive activity — will possibly remain inaccessible for decades.

  3. A Raman model for determining the chemical composition of silicate glasses

    NASA Astrophysics Data System (ADS)

    Di Genova, Danilo; Morgavi, Daniele; Hess, Kai-Uwe; Neuville, Daniel R.; Perugini, Diego; Dingwell, Donald B.

    2015-04-01

    Raman spectroscopy is a spectroscopic technique based on inelastic scattering of monochromatic light which provides information about molecular vibrations of the investigated sample. Since the discovery of the Raman Effect (1928) in scattered light from liquids, the Raman investigation has been extended to a large number of substances at different pressure-temperature conditions. Recently, the Raman instrument setup has rapidly grown thanks to the progress in development of lasers, charge coupled devices and confocal systems (see Neuville et al. 2014 for a review). Here we present the first Raman model able to determine the chemical composition of silicate glasses. In this study we combine chemical analysis from magma mixing experiments between remelted basaltic and rhyolitic melts, with a high spatial resolution Raman spectroscopy investigation; we focus on tracking the evolution of the Raman spectrum with chemical composition of silicate glasses. The mixing process is driven by a recently-developed apparatus that generates chaotic streamlines in the melts (Morgavi et al., 2013), mimicking the development of magma mixing in nature. From these experiments we obtained a glassy filament with a chemical composition ranging from a basalt to a rhyolite. Raman and microprobe measurements have been performed on a filament of ~1000 ?m diameter, every 2.5-20 ?m. The evolution of the acquired Raman spectra with the measured chemical composition has been parametrized by combining both the Raman spectra of the basaltic and rhyolitic end-members. Using the developed Raman model we have been able to determine the chemical composition (mol% of SiO2, Al2O3, FeO, CaO, MgO, Na2O and K2O) of the investigated filament. Additionally, the proposed Raman model has been successfully tested using external remelted natural samples; reference glasses (Jochum et al., 2000), a remelted basalt, andesite from Etna and Montserrat respectively. Finally, as the Raman spectrum depends on the silicate structure yielding information about network-forming structural units (Qn species, where n indicates the number of bridging oxygen), we combined the deconvoluted Raman spectra, in the rhyolitic field, with the chemical analyses and abundance of Qn species. This demonstrate how the evolution of silicate structure might control the bimodal eruptive style (explosive vs effusive) as shown by silica-rich volcanic systems. References: D. Morgavi et al., 2013. Morphochemistry of patterns produced by mixing of rhyolitic and basaltic melts. JVGR, 253, 87-96. D. R. Neuville, et al. 2014. Advances in Raman Spectroscopy Applied to Earth and Material Sciences. Rev. Min. Geochem., 78, 509-541.

  4. Geochemistry of mid ocean ridge basalts (MORB) from the northern Central Indian Ridge between 7°46 and 13°20 S: Implication of mantle heterogeneity influenced by Reunion hotspot plume?

    NASA Astrophysics Data System (ADS)

    Lee, J.; Lee, I.; Lee, S.; Kim, J.

    2010-12-01

    Between the Rodrigues Triple Junction (RTJ) and Carlsberg Ridge, The Central Indian Ridge (CIR) is a slow-intermediate spreading-rate (~ 43mm/year) plate boundary formed during separation of the Mascarene Plateau from the Chagos-Lacadives Ridge. Although several samplings of basaltic rocks were carried out in previous explorations on Indian Ridge, no systematic studies on the petrogenesis of CIR, especially for north of 18°S have been reported yet. We present the major and trace element composition of lavas dredged along the spreading axis of the northern CIR between 7°46 and 13°20 S. The mineralogy of the CIR MORB mainly consists of tiny needle- and/or lath-like plagioclase microlites (~45%), sub- to anhedral olivine (~15%), small anhedral clino-pyroxene (~10%), and intersertal/intergranular Fe-Ti oxide glass matrix (~30%). In the whole rock and glass chemistry, the samples show the very similar pattern of compositional variation in SiO2, Al2O3, FeO, and CaO concentration against MgO (6.59 ~ 8.68 wt %), although relatively less compatible elements (TiO2, Na2O, K2O, and P2O5) show linear trend. Plottings of Na8.0, Fe8.0, and CaO/Al2O3 vs. depth are examined to check the varying extents of partial melting and the global correlations. The results broadly agree with the global trend of MORB and fall within the dry MORB domain. Concentration of light rare earth elements (LREE) vary widely in the analyzed rock samples ((La/Sm)N ? 0.68 ~ 1.41 and (Nb/Yb)N ? 0.42 ~ 1.93). In spider diagram normalized by primitive mantle, the volcanic lavas show systematic increase of incompatible element concentration from south (segment 1) to north (segment 5), which could be attributed to the influence of enriched source in south of the study area. However, basalts from segment 2 are significantly enriched in incompatible elements. Plots of the ratios of several incompatible elements versus La/Sm ratio show a linear trend which could be attributed to the mixing of depleted and enriched components. The preliminary result of geochemical analyses of the volcanic lavas shows geographic trend of increase in incompatible elements north to south along the spreading axis, which might be influenced by Reunion hotspot plume. However, the evolution of enriched magma by various degree of melting also should be examined for the detailed interpretation, especially for the anomalously enriched lavas from the segment 2.

  5. Petrology and geochemistry of Mesozoic granitic rocks from the Nansha micro-block, the South China Sea: Constraints on the basement nature

    NASA Astrophysics Data System (ADS)

    Yan, Quanshu; Shi, Xuefa; Liu, Jihua; Wang, Kunshan; Bu, Wenrui

    2010-01-01

    There are several micro-blocks dispersed in the South China Sea (SCS), e.g., Xisha-Zhongsha block, Nansha block and Reed-Northeastern Palawan block, etc., but detailed petrological constraints on their basement nature were previously lacking. The magmatic ages for granitic rock samples from two dredge stations in the Nansha micro-block vary from 159 to 127 Ma, which are comparable to magmatic activities occurred in the northern margin (Pearl river mouth), HongKong and East China. Petrographic characteristics, major-, trace element and Sr-Nd isotopic data of nine samples from two dredged station performed in the Nansha micro-block, the SCS, are reported. Petrographically, these granitic rocks can be divided into two groups which underwent a complex history of magmatic process, i.e., tonalitic rock (Group I) and monzogranitic rock (Group II). The Rittmann index ( ?) for these rocks (1.9-3.1) suggest that they belong to calc-alkaline rocks. Group I rocks which is of typical I-type, have higher contents of TiO 2, Al 2O 3, FeO, MgO, CaO, Na 2O and P 2O 5, but lower values of SiO 2 and K 2O, when compared with those of Group II with I-type characteristics. Group I rocks are produced by partial melting of older Precambrian basement with the variable influence of mantle-derived magma which results from the interaction of released fluids from the subducted slab and the overlying mantle wedge in a general convergent margin setting, and Group II rocks result from partial melting of lower crustal basic rocks (amphibolite) and/or further partial melting of the Group I rocks associated with the variable influence from the underplating mantle-derived magma resulting from lithospheric extensional regime. Both Groups I and II have undergone assimilation and fractional crystallization (AFC) processes during its petrogenesis. This study therefore demonstrates that there exists a continental basement within micro-blocks in the South China Sea, and further supports the idea that a Middle Jurassic to Mid-Cretaceous subduction zone existed across the temporary Taiwan, Palawan to Southern Vietnam, which was associated with westward to northestward convergence of the Pacific Plate during Late Mesozoic. We suggest that this subduction zone may have been connected with the paleo-Pacific plate subduction zone offshore eastern China during Mesozoic era. This study provides petrologic data for the pre-Cenozoic tectonic evolution of the South China Sea.

  6. High-Mg carbonatitic microinclusions in some Yakutian diamonds—a new type of diamond-forming fluid

    NASA Astrophysics Data System (ADS)

    Klein-BenDavid, Ofra; Logvinova, Alla M.; Schrauder, Marcus; Spetius, Zladislav V.; Weiss, Yaakov; Hauri, Erik H.; Kaminsky, Felix V.; Sobolev, Nikolay V.; Navon, Oded

    2009-11-01

    The composition of microinclusions in 26 fibrous cubic and coated diamonds from the Daldyn-Alakit kimberlite field, Yakutia were studied using EPMA and FTIR and the carbon isotopic composition of 4 of the diamonds was studied using SIMS. Fifteen diamonds carry carbonatitic high-density fluids (HDFs) with high MgO content (17-28 wt.%) whereas the MgO content of fluids in other diamonds does not exceed 14 wt.%. We propose that the two groups are distinct and evolved separately. The low-Mg suite is similar to previously reported carbonatitic to silicic HDFs from Africa and Brazil. The high-Mg suite is carbonatitic, but its composition is distinct from previously defined end-members. As the MgO content decreases from 28 to 17 wt.%, CaO, Na 2O, K 2O and Cl also decrease while the silica, Al 2O 3, TiO 2 and P 2O 5 contents remain constant. Additionally, the water band in the FTIR spectra of high-Mg HDFs is wider relative to the water band in the spectra of low-Mg carbonatitic HDFs. By combining EPMA and FTIR data, we have constrained the major element composition of the high-Mg carbonatitic end-member, which comprises 78 wt.% carbonates, 9% silicates, 6% water, 5% apatite and 2% halides. The composition of the high-Mg suite is closer to that of near-solidus melts of fertile carbonate peridotites and harzburgites. Thus, it should be possible to produce the Mg-rich HDF either by incipient melting, or by cooling and crystallization of a proto-kimberlitic melt at depth. However, the peridotitic system alone cannot explain the high alkali and Cl content of the fluids. We suggest that the elevated alkali and Cl content of the high-Mg carbonatites are related to interaction of carbonate peridotite with saline fluids, or of peridotite with chloride-carbonate melts. The major element composition of the high-Mg carbonatitic HDF is dominated by the low-fraction melts of the peridotite while the content of potassium and other incompatible elements is influenced by the contribution of the saline or carbonatitic fluids.

  7. Chemical mass transfer in magmatic processes IV. A revised and internally consistent thermodynamic model for the interpolation and extrapolation of liquid-solid equilibria in magmatic systems at elevated temperatures and pressures

    NASA Astrophysics Data System (ADS)

    Ghiorso, Mark S.; Sack, Richard O.

    1995-03-01

    A revised regular solution-type thermodynamic model for twelve-component silicate liquids in the system SiO2 TiO2 Al2O3 Fe2O3 Cr2O3 FeO MgO CaO Na2O K2O P2O5 H2O is calibrated. The model is referenced to previously published standard state thermodynamic properties and is derived from a set of internally consistent thermodynamic models for solid solutions of the igneous rock forming minerals, including: (Mg, Fe2+, Ca)-olivines, (Na, Mg, Fe2+, Ca)M2 (Mg, Fe2+, Ti, Fe3+, Al)M1 (Fe3+, Al, Si)2 TETO6- pyroxenes, (Na,Ca,K)-feldspars, (Mg, Fe2+) (Fe3+, Al, Cr)2O4-(Mg, Fe2+)2 TiO4 spinels and (Fe2+, Mg, Mn2+)TiO3-Fe2O3 rhombohedral oxides. The calibration utilizes over 2,500 experimentally determined compositions of silicate liquids coexisting at known temperatures, pressures and oxygen fugacities with apatite ±feldspar ±leucite ±olivine ±pyroxene ±quartz ±rhombohedral oxides ±spinel ±whitlockite ±water. The model is applicable to natural magmatic compositions (both hydrous and anhydrous), ranging from potash ankaratrites to rhyolites, over the temperature ( T) range 900° 1700° C and pressures ( P) up to 4 GPa. The model is implemented as a software package (MELTS) which may be used to simulate igneous processes such as (1) equilibrium or fractional crystallization, (2) isothermal, isenthalpic or isochoric assimilation, and (3) degassing of volatiles. Phase equilibria are predicted using the MELTS package by specifying bulk composition of the system and either (1) T and P, (2) enthalpy (H) and P, (3) entropy (S) and P, or (4) T and volume (V). Phase relations in systems open to oxygen are determined by directly specifying the f o2 or the T-P-f o2 (or equivalently H- P-f o2, S- P-f o2, T-V- f o2) evolution path. Calculations are performed by constrained minimization of the appropriate thermodynamic potential. Compositions and proportions of solids and liquids in the equilibrium assemblage are computed.

  8. Neoarchean paleoweathering of tonalite and metabasalt: Implications for reconstructions of 2.69Ga early terrestrial ecosystems and paleoatmospheric chemistry

    USGS Publications Warehouse

    Driese, S.G.; Jirsa, M.A.; Ren, M.; Brantley, S.L.; Sheldon, N.D.; Parker, D.; Schmitz, M.

    2011-01-01

    Field and laboratory investigations of a 2690.83Ma (207Pb/206Pb age of Saganaga Tonalite) unconformity exposed in outcrop in northeastern Minnesota, USA, reveal evidence for development of a deep paleoweathering profile with geochemical biosignatures consistent with the presence of microbial communities and weakly oxygenated conditions. Weathering profiles are characterized by a 5-50m thick regolith that consists of saprolitized Saganaga Tonalite and Paulson Lake succession basaltic metavolcanic rocks retaining rock structure, which is cross-cut by a major unconformity surface marking development of a successor basin infilled with alluvial deposits. The regolith and unconformity are overlain by thick conglomerate deposits that contain both intrabasinal (saprock) as well as extrabasinal detritus. Thin-section microscopy and electron microprobe analyses reveal extensive hydrolysis and sericitization of feldspars, exfoliation and chloritization of biotite, and weathering of Fe-Mg silicates and Cu-Fe sulfides; weathering of Fe-Ti oxides was relatively less intense than for other minerals and evidence was found for precipitation of Fe oxides. Geochemical analyses of the tonalite, assuming immobile TiO2 during weathering (??Ti,j), show depletion of SiO2, Al2O3, Na2O, CaO, MgO, and MnO, and to a lesser degree of K2O, relative to least-weathered parent materials. Significant Fe was lost from the tonalite. A paleoatmospheric pCO2 of 10-50 times PAL is estimated based on geochemical mass-balance of the tonalite profile and assuming a formation time of 50-500Kyr. Interpretations of metabasalt paleoweathering are complicated by additions of sediment to the profile and extensive diagenetic carbonate (dolomite) overprinting. Patterns of release of P and Fe and retention of Y and Cu in tonalite are consistent with recent laboratory experiments of granite weathering, and with the presence of acidic conditions in the presence of organic ligands (produced, for example, by a primitive microbial community) during weathering. Cu metal in the profile may document lower pO2 than present day at the surface. Comparison with previous studies of weathered tonalite and basalt (Denison, 2.45-2.22Ga) in Ontario, Canada, reveal general similarities in paleoweathering with our study, as well as important differences related to lower paleoatmospheric pO2 and terrestrial biosignature for the older Minnesota profile. A falling water table in the Alpine Lake locality is presumed to have promoted formation of this gossan-like deep-weathering system that extends to 50-m depth. ?? 2011 Elsevier B.V.

  9. Geochemistry of K/T-boundary Chicxulub ejecta of NE-Mexico

    NASA Astrophysics Data System (ADS)

    Harting, M.; Deutsch, A.; Rickers, K.

    2003-12-01

    Many K/T sections all over the world contain impact spherules supposed related to the Chicxulub event. This study focus on ejecta layers in NE-Mexican profiles. We carried out systematic XRF and synchrotron radiation measurements on such spherules at the HASYLAB and ANKA facilities as well as microprobe analyses (CAMECA SX50). Area scans on tektite-like material of the Bochil section reveal a pronounced zonation in the inner part, dominated by Ba and Sr whereas secondary CaCO3 dominates in the altered margin. The composition of the spherules from the Mesa-Juan Perez section differ significantly from the Beloc (Haiti) and Bochil tektite glasses. At Mesa-Juan Perez, spherules are either extremely rich in Fe and Ca or consist of smectite, some of those carry carbonate inclusions. Yttrium, La and Ce are zoned within the smectite with concentrations below the detection limit and up to 20 æg/g The Ca-rich inclusions are enriched in Y (up to 35 æg/g) and La (18 æg/g) and, compared to the surrounding smectite, also in Ce (up to 34 æg/g). The Ce enrichment in spherules from the Mesa-Juan Perez section indicates impact-melted carbonates of the Yucatan carbonate platform as possible precursor rocks. Recent investigations focus on the chemistry of melt rock samples from the PEMEX wells Yucatan-6 and Chicxulub-1: Their average composition (mean of 250 data points in wt-percent ) is 61.6 for SiO2, 0.16 for TiO2, 18.07 for Al2O3, 0.01 for Cr2O3, 1.98 for Na2O, 1.5 for FeO, 0.05 for MnO, 0.01 for NiO, 0.31 for MgO, 9.14 for K2O, 3.44 for CaO, and 0.01 for SO2. These results are in some cases comparable to the geochemistry of ejecta glasses, e.g. from Beloc (Haiti).

  10. Carbonate Stability and Melt Composition in Peridotite-CO2 System to 20 GPa

    NASA Astrophysics Data System (ADS)

    Ghosh, S.; Ohtani, E.; Litasov, K. D.; Suzuki, A.; Terasaki, H.

    2005-12-01

    Carbon dioxide and water are the most important volatile constituents in the Earth and they produce drastic changes in the melting phase relations and partial melt compositions of the mantle peridotite. Study of the peridotite-CO2 system is closely related to petrogenesis of kimberlite and diamond. There are a few high pressure mineral inclusions (i.e. majorite garnet and Ca and Mg perovskite) in diamond which suggest that kimberlites may be originated from the transition zone and lower mantle. The phase relations and melt compositions in the CO2-bearing peridotite at high pressures are poorly constrained, however the kimberlite and basalt-CO2 systems have been studied intensively. Simplified peridotite-CO2 system (like CMS or CMAS) has been studied at pressures up to 12 GPa (Canil and Scarfe, 1990), whereas complex peridotite-CO2 systems have been investigated only at lower pressures (up to 4 GPa, e.g. Wendlandt and Mysen, 1980). In this work we report the preliminary results on the phase relations and melt compositions of a model peridotite-CO2 system determined at 10-20 GPa and temperature range from 1200 to 2100oC. Our results show that solidus of carbonated peridotite is consistent with low-pressure data for CMAS-CO2 system. Liquidus phase at 10-20 GPa is majorite garnet. At 10-15 GPa, crystallization sequence with decreasing temperature is garnet, olivine and clinoenstatite. Magnesite is the most important CO2-rich phase stable in peridotite up to 1600oC at 20 GPa. The partial melt formed by 10-25% melting at 10-20 GPa has high MgO (26-34 wt.%) and FeO (7.0-10.4 wt.%) and low SiO2 (18-36 wt.%) and Al2O3 (0.5-1.3 wt.%) contents. It also contains 6-12 wt.% CaO, 0.6-2.0 wt.% Na2O and 0.1-0.3 wt.% K2O. The CO2 contents in the melts are 14-32 wt.%. The SiO2-poor nature of the partial melts is different from the results for melting of anhydrous or water-bearing peridotite. Partial melting of hydrous peridotite produces the melts enriched in SiO2, which can be related to komatiite magmas. The composition of low degree partial melts (10%) in present experiments is close to magnesiocarbonatites, whereas higher degree melting (20-25%) produce melts, which is close to kimberlite magmas.

  11. Stratigraphy and Petrology of the Grande Soufriere Hills Volcano, Dominica, Lesser Antilles

    NASA Astrophysics Data System (ADS)

    Daly, G.; Smith, A. L.; Garcia, R.; Killingsworth, N.

    2007-12-01

    The Grande Soufriere Hills volcanic center is located on the south east coast of the island of Dominica in the Lesser Antilles. Although the volcano is deeply dissected, a distinct circular crater that opens to the east can be observed. Within the crater is a lava dome and unconsolidated pyroclastic deposits mantle the southeast flanks of the volcano. These pyroclastic deposits are almost entirely matrix-supported block and ash flows and surges suggesting that Pelean-style eruptions have dominated its most recent activity. Within this sequence is a relatively thin (30-50 cm) clast-supported deposit that has been interpreted as a possible blast deposit. Two age dates from these younger deposits suggest that much of this activity occurred between l0,000 and 12,000 years ago. On the southeastern coast at Pointe Mulâtre and extending approximately 4 km north and at a maximum 2 km west, is a megabreccia of large (up to 3 m) flow-banded andesite clasts set in a semi-lithified medium grained ash matrix. At Pointe Mulâtre this megabreccia is overlain by unconsolidated block and ash flow deposits. To the north of the megabreccia, exposures in the sea cliffs reveal a consolidated sequence of well-bedded alternating coarse and fine deposits suggesting deltaic foreset beds; which in turn appears to be overlain by a yellow- colored relatively coarse flow deposit with an irregular upper surface. The uppermost deposits in the sea cliffs are a sequence of unconsolidated block and ash flow deposits and interbedded fluviatile conglomerates equivalent to the younger flow deposits logged inland. Volcanic rocks from the Grande Soufriere Hills are all porphyritic andesites often containing hypabyssal inclusions. Dominant phenocrysts are plagioclase often with inclusion-rich cores and well developed zoning. Mafic phenocrysts include hornblende, augite and hypersthene. Geochemically these andesites range from 58- 63% SiO2 and show trends of decreasing values for Al2O3, FeO, MgO, CaO, TiO2, Sr, V, and Sc and increasing values for Na2O, K2O, Ba, Rb, and Zr with increasing silica. Samples from the megabreccia can be chemically distinguished from the younger rocks of this center. Petrologic models suggest that the younger rocks from the Grand Soufriere Hills can be produced by fractional crystallization of basaltic magma such as those erupted from other centers (such as Morne Anglais to the west). Minor variations within this suite of andesites can be related to upper crustal fractionation of phenocryst phases.

  12. Calcinaksite, KNaCa(Si4O10) H2O, a new mineral from the Eifel volcanic area, Germany

    NASA Astrophysics Data System (ADS)

    Chukanov, Nikita V.; Aksenov, Sergey M.; Rastsvetaeva, Ramiza K.; Blass, Günter; Varlamov, Dmitry A.; Pekov, Igor V.; Belakovskiy, Dmitry I.; Gurzhiy, Vladislav V.

    2015-03-01

    The new mineral calcinaksite, ideally KNaCa(Si4O10) · H2O, the first hydrous and Ca-dominant member of the litidionite group, is found in a xenolith of metamorphosed carbonate-rich rock from the southern lava flow of the Bellerberg volcano, Eastern Eifel region, Rheinland-Pfalz, Germany. It is associated with wollastonite, gehlenite, brownmillerite, Ca2SiO4 (larnite or calcio-olivine), quartz, aragonite, calcite, jennite, tobermorite and ettringite. Calcinaksite occurs as clusters of colourless to light-grey subhedral prismatic crystals. The mineral is brittle, with Mohs' hardness of 5; Dmeas is 2.62(2) g/cm3 and Dcalc is 2.623 g/cm3. The IR spectrum shows the presence of H2O molecules forming three different H-bonds. Calcinaksite is optically biaxial (+), ? = 1.542(2), ? = 1.550(2), ? = 1.565(3), 2V meas = 75(10). The chemical composition (electron-microprobe data, H2O determined by the Alimarin method, wt%) is: Na2O 6.69, K2O 12.01, CaO 15.04, FeO 0.59, SiO2 61.46, H2O 4.9, total 100.69. The empirical formula is H2.11 K0.99Na0.84Ca1.04Fe0.03Si3.98O11. The crystal structure was solved and refined to R 1 = 0.053, wR 2 = 0.075 based upon 3057 reflections having I > 3?(I). Calcinaksite is triclinic, space group P overline{1} , a = 7.021(2), b = 8.250(3), c = 10.145(2) Å. ? = 102.23(2)°, ? = 100.34(2)°, ? = 115.09(3)°, V = 495.4(3) Å3, Z = 2. The strongest reflections of the X-ray powder pattern [d, Å (I,%) (hkl)] are: 3.431 (70) (-121, -211, -210, 012, 0-22), 3.300 (67) (-031), 3.173 (95) (-103, -201, -220, 003, 111), 3.060 (100) (-212, 2-11, -221, 200, -1-13, 021, -202), 2.851 (83) (0-23, -122, 1-13, 1-31), 2.664 (62) (1-23, -222, 201).

  13. A study of formation and photoluminescence properties of ZnO quantum dot doped zinc-alumino-silicate glass ceramic

    NASA Astrophysics Data System (ADS)

    Ghaemi, Bahram; Zhao, Gaoling; Jie, Guangtao; Xi, Haidong; Li, Xiuming; Wang, Jianxun; Han, Gaorong

    2011-04-01

    Transparent Al 2O 3-SiO 2-ZnO-R 2O glass ceramics were fabricated by melting method. The effects of the different kind of alkali ions on the formation of the transparent glass ceramic were studied. X-ray diffraction and high resolution transmission electron microscope were measured to study the microstructure of the samples. The results showed that, transparent glass ceramic including ZnO quantum dots was obtained after heat treatment from 700 °C to 800 °C for the sample containing K 2O. While glasses containing Li 2O and Na 2O were opal after heat treatment. Photoluminescence properties of the K 2O contained samples were studied. It was found that the photoluminescence peak shifted to longer wavelength when the heat treatment temperature and time increased, which can be ascribed to the increasing of ZnO quantum dots size.

  14. Geochemistry of black shales from the Lower Cretaceous Paja Formation, Eastern Cordillera, Colombia: Source weathering, provenance, and tectonic setting

    NASA Astrophysics Data System (ADS)

    Campos Alvarez, N. O.; Roser, B. P.

    2007-04-01

    The major and trace element characteristics of black shales from the Lower Cretaceous Paja Formation of Colombia are broadly comparable with those of the average upper continental crust. Among the exceptions are marked enrichments in V, Cr, and Ni. These enrichments are associated with high organic carbon contents. CaO and Na 2O are strongly depleted, leading to high values for both the Chemical Index of Alteration (77-96) and the Plagioclase Index of Alteration (86-99), which indicates derivation from a stable, intensely weathered felsic source terrane. The REE abundances and patterns vary considerably but can be divided into three main groups according to their characteristics and stratigraphic position. Four samples from the lower part of the Paja Formation (Group 1) are characterized by LREE-enriched chondrite-normalized patterns (average La N/Yb N = 8.41) and significant negative Eu anomalies (average Eu/Eu ? = 0.63). A second group of five samples (Group 2), also from the lower part, have relatively flat REE patterns (average La N/Yb N = 1.84) and only slightly smaller Eu anomalies (average Eu/Eu ? = 0.69). Six samples from the middle and upper parts (Group 3) have highly fractionated patterns (average La N/Yb N = 15.35), resembling those of Group 1, and an identical average Eu/Eu ? of 0.63. The fractionated REE patterns and significant negative Eu anomalies in Groups 1 and 3 are consistent with derivation from an evolved felsic source. The flatter patterns of Group 2 shale and strongly concave MREE-depleted patterns in two additional shales likely were produced during diagenesis, rather than reflecting more mafic detrital inputs. An analysis of a single sandstone suggests diagenetic modification of the REE, because its REE pattern is identical to that of the upper continental crust except for the presence of a significant positive Eu anomaly (Eu/Eu ? = 1.15). Felsic provenance for all samples is suggested by the clustering on the Th/Sc-Zr/Sc and Gd N/Yb N-Eu/Eu ? diagrams. Averages of unmodified Groups 1 and 3 REE patterns compare well with cratonic sediments from the Roraima Formation in the Guyana Shield, suggesting derivation from a continental source of similar composition. In comparison with modern sediments, the geochemical parameters (K 2O/Na 2O, La N/Yb N, La N/Sm N, Eu/Eu ?, La/Sc, La/Y, Ce/Sc) suggest the Paja Formation was deposited at a passive margin. The Paja shales thus represent highly mature sediments recycled from deeply weathered, older, sedimentary/metasedimentary rocks, possibly in the Guyana Shield, though Na-rich volcanic/granitic rocks may have contributed to some extent.

  15. Thermodynamics and phase equilibria of the silicate-fluoride-water systems: Implications for fluorine-bearing granites

    NASA Astrophysics Data System (ADS)

    Dolejs, David

    The progressive enrichment in volatiles and light incompatible elements observed during upper-crustal differentiation of granitic and rhyolitic magmas leads to significant changes in melt physical-chemical properties and has important implications for ore deposition and volcanic devolatization. Thermodynamic calculations and experimental studies of melting equilibria in the Na 2O-K2O-Al2O3-SiO2-F 2O-1-H2O system are used to evaluate mineral stabilities, fluid compositions, the extent of fluoride-silicate liquid-liquid immiscibility, fluorine and water solubility limits and differentiation paths of natural fluorine-bearing silicic magmas. The interaction of fluorine with rock-forming aluminosilicates corresponds to progressive fluorination by the thermodynamic component F2O-1. Formation of fluorine-bearing minerals first occurs in peralkaline and silica-undersaturated systems that buffer fluorine concentrations at very low levels (villiaumite, fluorite). The highest concentrations of fluorine are achieved in peraluminous silica-oversaturated systems, saturated with fluorite or topaz. Thermodynamic models of fluorosilicate melts indicate clustering of silicate tetrahedra in the Na2O-SiO 2-F2O-1 system, whereas initial NaAl-F short-range order evolves into partial O-F disorder in the albite-cryolite system. Experiments performed at 520-1100°C and 0.1-100 MPa completely describe liquidus relations and differentiation paths of fluorine-bearing felsic magmas. Coordination differences and short-range order effects between [NaAl]-F, Na-F vs. Si-O lead to the fluoride-silicate liquid immiscibility, which extends from the silica-cryolite binary through the peralkaline albite-silica-cryolite ternary and closes in multicomponent, topaz-bearing systems owing to the destabilizing effect of increasing peraluminosity. Liquidus relations indicate that fluoride-silicate liquid-liquid immiscibility is inaccessible to quartz-feldspar-saturated granitic melts. Differentiation paths of Ca-poor granitic melts with fluorine reach the cryolite or topaz saturation surface, respectively, and, depending on aluminosity buffering by rock-forming silicates, may evolve to the high fluorine concentrations of the haplogranite-topaz-cryolite-H2O eutectic at max. 5.9 wt. % F, 540°C, 100 MPa and H2O saturation. In contrast, the potential of Ca-rich silicic magmas for fluorine enrichment is severely limited by fluorite crystallization. Fluorite solubility is determined by individual concentrations of CaO and F2O-1 in the melt and exhibits a minimum at subaluminous compositions due to the short-range ordering of Ca-Al and alkali-F. These results provide a framework for differentiation of natural fluorine-bearing magmas and have applications in electrolytic and flux metallurgy.

  16. Lanthanum and neodymium solubility in simplified SiO{sub 2}-B{sub 2}O{sub 3}-Na{sub 2}O-Al{sub 2}O{sub 3}-CaO high level waste glass

    SciTech Connect

    Kidari, Abdessamad; Bardez-Giboire, Isabelle [CEA, DEN, DTCD/SECM/LDMC - Marcoule, Bagnols-sur-Ceze F-30207, (France); Dussossoy, Jean-Luc; Magnin, Magali [CEA, DEN, DTCD/SECM/LMPA - Marcoule, Bagnols-sur-Ceze F-30207, (France); Brackx, Emmanuelle [CEA, DEN, DTEC/SGCS/LMAC - Marcoule, Bagnols-sur-Ceze F-30207, (France); Caurant, Daniel [Ecole Nationale Superieure de Chimie de Paris, Laboratoire de Chimie de la Matiere Condensee de Paris, UMR CNRS 7574, Paris, (France)

    2012-08-15

    Lanthanum and neodymium incorporation in simplified high level waste glasses has been investigated for SiO{sub 2}B{sub 2}O{sub 3}Na{sub 2}OAl{sub 2}O{sub 3}CaO compositions quenched from 1200 degrees C, for varying La /(La + Nd) (atomic) and increasing rare-earth oxides contents. In this system and beyond the solubility limit, rare-earths (RE) elements are reported to form apatite phases with the general formula Ca{sub 2}RE{sub 8}(SiO{sub 4}){sub 6}O{sub 2}. In the current study, speciation of these trivalent RE{sup 3+} cations in both amorphous network and crystal phases was determined from X-ray diffraction, scanning electron microscopy, optical absorption at 10 K, Raman spectroscopy, and electron probe microanalysis. It appeared that RE{sub 2}O{sub 3} solubility was higher for La -rich formulations than for Nd -rich ones and that an increase in the RE oxide content reduces the connectivity of the network building units through formation of non-bridging oxygens at the expense of the oxygen bridges. This depolymerization of the glass network did not affect neodymium environment which consisted in silicate tetrahedra. The composition of the apatite crystals was found to be affected by the La /(La + Nd) of the parent glass and deviation from the ideal composition (Ca{sub 2}RE{sub 8}(SiO{sub 4}){sub 6}O{sub 2}) occurred in the neodymium end of the system. It thus appears that both RE{sub 2}O{sub 3} solubility and crystal composition are strongly dependent on the type and crystal chemistry of the RE elements. (authors)

  17. Rectal cancer delivery of radiotherapy in adequate time and with adequate dose is influenced by treatment center, treatment schedule, and gender and is prognostic parameter for local control: Results of study CAO/ARO/AIO-94

    SciTech Connect

    Fietkau, Rainer [Department of Radiation Therapy, University of Rostock, Rostock (Germany)]. E-mail: rainer.fietkau@med.uni-rostock.de; Roedel, Claus [Departments of Radiation Therapy and Surgery, University of Erlangen, Erlangen (Germany); Hohenberger, Werner [Departments of Radiation Therapy and Surgery, University of Erlangen, Erlangen (Germany); Raab, Rudolf [Department of Surgery, Klinikum Oldenburg, Oldenburg (Germany); Hess, Clemens [Departments of Radiation Therapy and General Surgery, University of Goettingen, Goettingen (Germany); Liersch, Torsten [Departments of Radiation Therapy and General Surgery, University of Goettingen, Goettingen (Germany); Becker, Heinz [Departments of Radiation Therapy and General Surgery, University of Goettingen, Goettingen (Germany); Wittekind, Christian [Institute of Pathology, University of Leipzig, Leipzig (Germany); Hutter, Matthias [Department of Radiation Therapy, Krankenhaus Nordwest Frankfurt, Frankfurt (Germany); Hager, Eva [Department of Radiation Therapy, Krankenhaus Klagenfurt, Klagenfurt (Austria); Karstens, Johann [Department of Radiation Therapy, University of Hannover, Hannover (Germany); Ewald, Hermann [Department of Radiation Therapy, University of Schleswig-Holstein, Campus Kiel, Kiel (Germany); Christen, Norbert [Department of Radiation Therapy, Krankenhaus Dresden-Friedrichstadt, Dresden (Germany); Jagoditsch, Michael [Department of Surgery, Klinikum St. Veit, St. Veit (Austria); Martus, Peter [Institute of Biostatistics and Clinical Epidemiology, Charite Universitary Medicine Berlin, Berlin (Germany); Sauer, Rolf [Departments of Radiation Therapy and Surgery, University of Erlangen, Erlangen (Germany)

    2007-03-15

    Purpose: The impact of the delivery of radiotherapy (RT) on treatment results in rectal cancer patients is unknown. Methods and Materials: The data from 788 patients with rectal cancer treated within the German CAO/AIO/ARO-94 phase III trial were analyzed concerning the impact of the delivery of RT (adequate RT: minimal radiation RT dose delivered, 4300 cGy for neoadjuvant RT or 4700 cGy for adjuvant RT; completion of RT in <44 days for neoadjuvant RT or <49 days for adjuvant RT) in different centers on the locoregional recurrence rate (LRR) and disease-free survival (DFS) at 5 years. The LRR, DFS, and delivery of RT were analyzed as endpoints in multivariate analysis. Results: A significant difference was found between the centers and the delivery of RT. The overall delivery of RT was a prognostic factor for the LRR (no RT, 29.6% {+-} 7.8%; inadequate RT, 21.2% {+-} 5.6%; adequate RT, 6.8% {+-} 1.4%; p = 0.0001) and DFS (no RT, 55.1% {+-} 9.1%; inadequate RT, 57.4% {+-} 6.3%; adequate RT, 69.1% {+-} 2.3%; p = 0.02). Postoperatively, delivery of RT was a prognostic factor for LRR on multivariate analysis (together with pathologic stage) but not for DFS (independent parameters, pathologic stage and age). Preoperatively, on multivariate analysis, pathologic stage, but not delivery of RT, was an independent prognostic parameter for LRR and DFS (together with adequate chemotherapy). On multivariate analysis, the treatment center, treatment schedule (neoadjuvant vs. adjuvant RT), and gender were prognostic parameters for adequate RT. Conclusion: Delivery of RT should be regarded as a prognostic factor for LRR in rectal cancer and is influenced by the treatment center, treatment schedule, and patient gender.

  18. Juvenile accretion (2360-2330 Ma) in the São Francisco Craton, and implications for the Columbia supercontinent: evidence from U-Pb zircon ages, Sr-Nd-Hf and geochemical constraints

    NASA Astrophysics Data System (ADS)

    Teixeira, W.; Ávila, C.

    2012-12-01

    The Mineiro and the Itabuna-Salvador-Curaçá belts are segments of an Early Proterozoic orogen, in the São Francisco/West Congo-North Gabon craton. The latter segment includes island-arc rocks with preserved portions of the accretionary prism and back-arc basins, developed between 2.4 and 2.0 Ga. The Mineiro belt evolved marginally to the Minas passive margin basin (<2.55 to 2.35 Ga). It contains mainly granitoid rocks with ages between 2.25-2.20 Ga and 2.12-2.08 Ga, along with coeval back arc sequences. The overall framework includes regional metamorphism and related faults and shear zones across both belts. Similar tectonic features are portrayed by the West Central African belt (of Eburnean age) by considering the early contiguous African counterpart. We present an integrated geochronologic and geochemical study for the Resende Costa orthogneiss (Mineiro belt): the gneissic rocks are slightly metaluminous to peraluminous, subalkaline, show varied SiO2 (69 to 73wt.%) contents, and low K2O and high- Na2O +CaO ones. Chemically, they are compatible with high Al2O3 trondhjemites. They also show weak positive Eu/Eu* anomalies, low Rb (24 to 70ppm), Ba (500 to 1000ppm), Th (2.1 to 8.5ppm) contents, very high Sr/Y ratios (75 to 158) and variable LREE and low HREE patterns (Yb < 1.23 ppm). The Resende Costa pluton yields two U-Pb (LA-ICPMS) zircon crystallization ages (2358±10 Ma and 2356±12 Ma), while the zircon rims yield 2133±32 Ma, interpreted as the age of metamorphism. The Sm/Nd TDM whole rock model ages are between 2.35-2.50 Ga, whereas the ?Nd(t) values range from +1.2 to +3.0, ?Sr(t) from +10 to -6, and ?Hf(t) in zircon between -3 to +6. The nearby Ramos gneissic pluton gives U-Pb zircon age of 2331±17 Ma, TDM age of 2.4 Ga, ?Nd(t) +2.2, ?Hf(t) (-9/+9) and ?Sr(t) +40 values. The overall signature implies to short crustal residence for the protholiths with minor contamination during the petrogenesis. Published data reveal that the nearby Lagoa Dourada suite is coeval with the Resende Costa pluton. This suite consists of tonalites and trondhjemites with U-Pb crystallization ages of 2356 +3/-2 Ma and 2350 ± 4 Ma, and ?Nd(t) values from +1.0 to +2.1 (TDM = 2.4-2.5 Ga). Chemically, these rocks are metaluminous to slightly peraluminous, with low-Mg#, low-K2O and high-CaO, and varied SiO2 contents (?62 to 73wt.%). The Lagoa Dourada suite also shows high-Sr/Y ratios (?41 up to 81), high-(La/Yb)N ratios (?12 up to 46), and positive Eu/Eu* anomalies, likewise the Resende Costa rocks. From the above, a juvenile accretionary event (2.36-2.33 Ga) is first time defined in the Southern São Francisco craton, correlating well with the early stage of the Itabuna-Salvador-Curaçá belt, according to geologic evidence and isotopic inferences. Roughly contemporary provinces resulted from Early Proterozoic crustal growth are similarly documented in South America and West Africa, Laurentia, Baltica, Siberia, Central Australia, North China and India. From a geodynamic perspective, they are part of a global assembly that took place mainly between 2.0-1.9 Ga - the Columbia Supercontinent - as suggested by geologic correlations, age constraints and paleomagnetic evidences.

  19. New data on selected Ivory Coast tektites.

    NASA Technical Reports Server (NTRS)

    Cuttitta, F.; Carron, M. K.; Annell, C. S.

    1972-01-01

    Fourteen Ivory Coast tektites exhibit a range of bulk indices of refraction of 1.5156 to 1.5217 plus or minus 0.0004 and of bulk specific gravities of 2.428 to 2.502 plus or minus 0.005. Seven of these Ivory Coast (IVC) tektites were analyzed for major and minor element content. Compared to tektites from other strewn fields, their SiO2 content is low (67.2-69.1%), Al2O3 relatively high (15.8-16.8%), and total iron relatively high but with a more restricted range (6.3-6.8% as FeO). Their lime content is low (0.71-1.35%) compared to Australasian tektites but their MgO/CaO ratio (about 3.1) is unusually high. All other tektite groups have Na2O/K2O ratios less than unity, but the Na2O/K2O ratio of the IVC tektites is slightly greater than unity. Their K/Rb ratios range from 200 to 256 and average 227.

  20. Compositional data for twenty-one Fra Mauro lunar materials.

    NASA Technical Reports Server (NTRS)

    Rose, H. J., Jr.; Cuttitta, F.; Annell, C. S.; Carron, M. K.; Christian, R. P.; Dwornik, E. J.; Greenland, L. P.; Ligon, D. T., Jr.

    1972-01-01

    Major, minor, and trace element analyses are presented for two igneous rocks, six breccias, four microbreccias, two breccia clasts, and six soils, as well as a sample of sawdust from rock 14066. Evaluation of the data suggests that the samples from the Fra Mauro highlands have the same nonterrestrial characteristics shown previously by the samples returned from the mare regions by Apollo 11 and 12 - namely, a high refractory element content, a lower volatile element content, and an excess reducing capacity above that due to FeO. The Fra Mauro soils have higher concentrations of Al2O3, Na2O, and K2O and lower amounts of FeO and TiO2 than do the mare soils. They also show a bimodal distribution of Ni, B, and Nb. The highland breccias are richer in SiO2, Al2O3, MgO, Na2O, and K2O than those returned from the mare lowlands. FeO, TiO2, and MnO are lower in concentration at Fra Mauro, and the highland breccias are more complex mineralogically than those collected previously.

  1. Shlykovite KCa[Si4O9(OH)] · 3H2O and cryptophyllite K2Ca[Si4O10] · 5H2O, new mineral species from the Khibiny alkaline pluton, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Pekov, I. V.; Zubkova, N. V.; Filinchuk, Ya. E.; Chukanov, N. V.; Zadov, A. E.; Pushcharovsky, D. Yu.; Gobechiya, E. R.

    2010-12-01

    New minerals, shlykovite and cryptophyllite, hydrous Ca and K phyllosilicates, have been identified in hyperalkaline pegmatite at Mount Rasvumchorr, Khibiny alkaline pluton, Kola Peninsula, Russia. They are the products of low-temperature hydrothermal activity and are associated with aegirine, potassium feldspar, nepheline, lamprophyllite, eudialyte, lomonosovite, lovozerite, tisinalite, shcherbakovite, shafranovskite, ershovite, and megacyclite. Shlykovite occurs as lamellae up to 0.02 × 0.02 × 0.5 mm in size or fibers up to 0.5 mm in length usually combined in aggregates up to 3 mm in size, crusts, and parallel-columnar veinlets. Cryptophyllite occurs as lamellae up to 0.02 × 0.1 × 0.2 mm in size intergrown with shlykovite being oriented parallel to {001} or chaotically arranged. Separate crystals of the new minerals are transparent and colorless; the aggregates are beige, brownish, light cream, and pale yellowish-grayish. The cleavage is parallel to (001) perfect. The Mohs hardness of shlykovite is 2.5-3. The calculated densities of shlykovite and cryptophyllite are 2.444 and 2.185 g/cm3, respectively. Both minerals are biaxial; shlykovite: 2 V meas = -60(20)°; cryptophyllite: 2 V meas > 70°. The refractive indices are: shlykovite: ? = 1.500(3), ? = 1.509(2), ? = 1.515(2); cryptophyllite: ? = 1.520(2), ? = 1.523(2), ? = 1.527(2). The chemical composition of shlykovite determined by an electron microprobe (H2O determined from total deficiency) is as follows, wt %: 0.68 Na2O, 11.03 K2O, 13.70 CaO, 59.86 SiO2, 14.73 H2O; the total is 100.00. The empirical formula calculated on the basis of 13 O atoms (OH/H2O calculated from the charge balance) is (K0.96Na0.09)?1.05Ca1.00Si4.07O9.32(OH)0.68 · 3H2O. The idealized formula is KCa[Si4O9(OH)] · 3H2O. The chemical composition of cryptophyllite determined by an electron microprobe (H2O determined from the total deficiency) is as follows, wt %: 1.12 Na2O, 17.73 K2O, 11.59 CaO, 0.08 Al2O3, 50.24 SiO2, 19.24 H2O, the total is 100.00. The empirical formula calculated on the basis of (Si,Al)4(O,OH)10 (OH/H2O calculated from the charge balance) is (K1.80Na0.17)?1.97Ca0.99Al0.01Si3.99O9.94(OH)0.06 · 5.07H2O. The idealized formula is K2Ca[Si4O10] · 5H2O. The crystal structures of both minerals were solved on single crystals using synchrotron radiation. Shlykovite is monoclinic; the space group is P21/ n; a = 6.4897(4), b = 6.9969(5), c = 26.714(2)Å, ? = 94.597(8)°, V = 1209.12(15)Å3, Z = 4. Cryptophyllite is monoclinic; the space group is P21/ n; a = 6.4934(14), b = 6.9919(5), c = 32.087(3)Å, ? = 94.680(12)°, V= 1451.9(4)Å, Z = 4. The strongest lines of the X-ray powder patterns ( d, Å- I, [ hkl] are: shlykovite 13.33-100[002], 6.67-76[004], 6.47-55[100], 3.469-45[021], 3.068-57[ bar 1 21], 3.042-45[121], 2.945-62[ 23], 2.912-90[025, 12, 211]; cryptophyllite 16.01-100[002], 7.98-24[004], 6.24-48[101], 3.228-22[ bar 1 09], 3.197-27[0.0.10], 2.995-47[122], 2.903-84[123, 204, bar 1 24, 211], 2.623-20[028, 08, 126]. Shlykovite and cryptophyllite are members of new related structural types. Their structures are based on a two-layer packet consisting of tetrahedral Si layers linked with octahedral Ca chains. Mountainite, shlykovite and cryptophyllite could be combined into the mountainite structural family. Shlykovite is named in memory of Russian geologist V. G. Shlykov (1941-2007); the name cryptophyllite is from the Greek words meaning concealed and leaf that allude to its layered structure (phyllosilicate) in combination with a lamellar habit and intimate intergrowths with visually indistinguishable shlykovite. Type specimens of the minerals are deposited at the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow.

  2. Late Paleozoic granitoid magmatism in Chukotka and its relation to Ellesmerian orogeny in Arctic Alaska and Canada

    NASA Astrophysics Data System (ADS)

    Luchitskaya, Marina; Sokolov, Sergey; Kotov, Alexander; Katkov, Sergey; Sal'nikova, Elena; Yakovleva, Sonya

    2013-04-01

    Chukotka fold area (Mesozoides) was formed as a result of collision between Chukotka - Arctic Alaska microplate and active margin of Siberian continent [1]. At present the majority of researches distinguish at least three stages of granitoid magmatism of Chukotka Mesozoides: 147-139, 127-100 and 82.4-78.8 Ma [2]. Granites of first two stages intrude metamorphic basement and Paleozoic-Mesozoic fold structures. Formation of Early Cretaceous granitoids are often considered in relation to granite-metamorphic core complexes evolution [3-5]. Intrusion of the third stage granitoid intrusions corresponds to Okhotsk-Chukotka volcanic belt activity. At the same time in several publications there is information of existence of more ancient Paleozoic granitoids. For orthogneisses of East Chukotka there are age estimations 380-320 Ma (U-Pb SHRIMP, [6]). V.V.Akinin [7] showed that protoliths of Velinkenay and Kuekvun plutons have Late Devonian (380-360 Ma) age. Granites of Kibera Peninsula were dated as 439±32 Ma [Rb-Sr method, 8]. Besides basal conglomerates of Carboniferous deposits contain granite pebbles. At the same time on the existing geological maps granites are indicated as Early Cretaceous ones [9]. Thus there are contradictions on the age estimations and scales of Paleozoic and Mesozoic granitoid magmatism manifestation within Chukotka Mesozoides. As a result of this interregional correlations, first of all correlation of Caledonian and Ellesmerian orogenies events in Arctic region, are complicated. So we carried out U-Pb geochronological studies of some reference granitoid plutons of Central Chukotka, located in the cores of antiform structures, composed of Paleozoic deposits, namely granodiorites of Kibera and quartz syenites of Kuekvyun plutons (Kuul and Kuekvyun rises respectively). Granitoids of Kibera pluton (coastal clippings of Kibera Peninsula, coast of East-Siberian Sea) intrude terrigenous Devonian deposits with carbonate units which are overlain with erosion by Permian-Triassic carbonate-terrigenous and sandy-argillaceous deposits. Kibera pluton is composed mainly of Amph-Bi granites and granite-porphyres. Endocontact zone is presented by foliated Bi granodiorites which were dated. Within Kuekvyun Rise [2] in the core of lineated antiform structure Devonian deposits, metamorphosed to amphibolite facies and deformed, are exposed. Earlier such structures were considered as horst-like saliences of Paleozoic cover and crystalline basement, now, as structures of granite-metamorphic core complexes [3-5]. In the central part of antiform there are micaceous and Gar-Bi schists, marbled limestones, Q-Fsp-Ep-Bi-Amph, Bi-Amph-Cpx schists, intruded by subconcordant bodies of Amph-Bi quartz syenites. At the peripheral parts of rise metamorphic complexes are discordantly overlain by terrigenous deposits of Permian(?)-Triassic age. Granodiorites of Kibera pluton (N 69°56' 50.5'', E172°40' 52,1''; SiO2=67.34%, TiO2=0.41%, Al2O3=14.72%, FeO=2.66%, Fe2O3=1.88%, MnO=0.074%, MgO=1.4%, CaO=2.48%, Na2O=3.71%, K2O=3.42%, P2O5=0.232%) have foliated texture, blastogranitic structure and are composed of quartz, plagioclase, potassic feldspar and biotite. Accessory minerals are sphene, allanite, apatite and zircon. Amph-Bi quartz syenites of Kuekvyun pluton (N 68°37'25.4'', E178°28'21,2'', SiO2=63.51%, TiO2=0.40%, Al2O3=16.57%, FeO=2.3%, Fe2O3=1.8%, MnO= 0.056%, MgO=0.99%, CaO=3.6%, Na2O=3.24%, K2O=5.83%, P2O5=0.245%) also have foliated texture, blastohypidiomorphic structure and are composed of plagioclase, potassic feldspar, amphibole, biotite and quartz. Sphene prevails within accessory minerals, allanite, apatite and zircon are also present. U-Pb geochronological studies for Kibera granodiorite are carried out for three microshots (10-15 grains) of most transparent zircon crystals, selected from 85-100 and 100-150 micron fractions. Points of isotope composition of studied microshots form Discordia, which lower intersection with Concordia correspond to age 353±5 Ma (upper intersection, 1183±660 Ma, ???=0.17). U-Pb geochronologica

  3. Hydrothermal alteration and mass exchange in the hornblende latite porphyry, Rico, Colorado

    NASA Astrophysics Data System (ADS)

    Larson, Peter B.; Cunningham, Charles G.; Naeser, Charles W.

    1994-03-01

    The Rico paleothermal anomaly, southwestern Colorado, records the effects of a large hydrothermal system that was active at 4 Ma. This hydrothermal system produced the deep Silver Creek stockwork Mo deposit, which formed above the anomaly's heat source, and shallower base and precious-metal vein and replacement deposits. A 65 Ma hornblende latite porphyry is present as widespread sills throughout the area and provided a homogenous material that recorded the effects of the hydrothermal system up to 8 km from the center. Hydrothermal alteration in the latite can be divided into a proximal facies which consists of two assemblages, quartz-illite-calcite and chlorite-epidote, and a distal facies which consists of a distinct propylitic assemblage. Temperatures were gradational vertically and laterally in the anomaly, and decreased away from the centra heat source. A convective hydrothermal plume, 3 km wide and at least 2 km high, was present above the stock-work molybdenum deposit and consisted of upwelling, high-temperature fluids that produced the proximal alteration facies. Distal facies alteration was produced by shallower cooler fluids. The most important shallow base and precious-metal vein deposits in the Rico district are at or close to the boundary of the thermal plume. Latite within the plume had a large loss of Na2O, large addition of CaO, and variable SiO2 exchante. Distal propylitized latite samples lost small amounts of Na2O and CaO and exchanged minor variable amounts of SiO2. The edge of the plume is marked by steep Na2O exchange gradients. Na2O exchange throughout the paleothermal anomaly was controlled by the reaction of the albite components in primary plagioclase and alkali feldspars. Initial feldspar alteration in the distal facies was dominated by reaction of the plagioclase, and the initial molar ratio of reactants (alkali feldspar albite component to plagioclase albite component) was 0.35. This ratio of the moles of plagioclase to alkali feldspar albite components that reacted evolved to 0.92 as the reaction progressed. Much of the alkali feldspar albite component in the proximal facies reacted while the, primary plagioclase was still unreacted, but the ratio for these assemblages increased to 1.51 when the plagioclase entered the reaction paragenesis. Plagioclase reaction during distal propylitic alteration resulted in pseudomorphic albite mixed with illite and a loss of Na2O. CaO is lost in the distal facies as hornblende reacts to chlorite, although some calcium may be fixed in calcite. CaO is added to the proximal facies as the quantity of chlorite replacing hornblende increases and epidote and calcite are produced.

  4. The effect of Mn, Fe and Cu ions on potash-glass corrosion

    Microsoft Academic Search

    M. Vilarigues; R. C. da Silva

    2009-01-01

    The corrosion products of potash-glass with manganese, iron and copper ions were studied by analysing the glass surfaces after being in contact with static water or using a stirrer for different periods. Glass samples with 56mol.% SiO2, 24mol.% CaO and 20mol.% K2O were prepared, with 1mol% of the different metal oxides. The basic composition of these glasses is analogous to

  5. Alkali content of alpine ultramafic rocks

    USGS Publications Warehouse

    Hamilton, W.; Mountjoy, W.

    1965-01-01

    The lower limit of abundance of sodium and potassium in ultramafic rocks is less than the threshold amount detectable by conventional analytical methods. By a dilutionaddition modification of the flame-spectrophotometric method, sodium and potassium have been determined in 40 specimens of alpine ultramafic rocks. Samples represent six regions in the United States and one in Australia, and include dunite, peridotite, pyroxenite, and their variably serpentinized and metamorphosed derivatives. The median value found for Na2O is 0.004 per cent, and the range of Na2O is 0.001-0.19. The median value for K2O is 0.0034 per cent and the range is 0.001-0.031 per cent. Alkali concentrations are below 0.01 per cent Na2O in 28 samples and below 0.01 per cent K2O in 35. Derivation of basalt magma from upper-mantle material similar to such ultramafic rocks, as has been postulated, is precluded by the relative amounts of sodium and potassium, which are from 200 to 600 times more abundant in basalt than in the ultramafic rocks. Similar factors apply to a number of other elements. No reasonable process could produce such concentrations in, for example, tens of thousands of cubic miles of uniform tholeiitic basalt. The ultramafic rocks might have originated either as magmatic crystal precipitates or as mantle residues left after fusion and removal of basaltic magma. Injection of ultramafic rocks to exposed positions is tectonic rather than magmatic. ?? 1965.

  6. Unique crystallization and formation of nonlinear optical (Na,K)NbO 3 phases in (Na,K)NbGeO 5 glasses

    NASA Astrophysics Data System (ADS)

    Narita, K.; Takahashi, Y.; Benino, Y.; Fujiwara, T.; Komatsu, T.

    2004-05-01

    Crystalline phases and second-order optical nonlinearities in crystallized glasses of (Na,K)NbGeO 5 (i.e., xNa 2O · (25- x)K 2O · 25Nb 2O 5 · 50GeO 2) are examined. The molar volume of the glasses decreases with increasing Na 2O content, indicating that the glass structure of NaNbGeO 5 glass is more compact compared with KNbGeO 5 glass. The optical basicity of the glasses is 0.94-0.95, implying that chemical bonds among constituents ions are basically very ionic. (Na,K)NbGeO 5 glasses exhibit a unique crystallization depending on the Na 2O/K 2O ratio. The main crystalline phase in crystallized NaNbGeO 5 glass is the NaNbGeO 5 phase. KNbGeO 5 glass shows a prominent bulk nanocrystallization giving nanocrystals of the K 3.8Nb 5Ge 3O 20.4 phase. A glass with the composition of K 3.8Nb 5Ge 3O 20.4 also shows a bulk nanocrystallization. The crystallized glasses with K 3.8Nb 5Ge 3O 20.4 and NaNbGeO 5 crystalline phases do not show a second harmonic generation (SHG) at room temperature. The nonlinear optical (Na,K)NbO 3 phases showing a SHG are formed at the surface (˜5 ?m) of crystallized glasses with x=15 and 20, giving an orientation of the (1 1 0) plane. The present study suggests the presence of mixed-alkali effect in the crystallization behavior of (Na,K)NbGeO 5 glasses.

  7. The effects of Na 2O\\/SiO 2 molar ratio, curing temperature and age on compressive strength, morphology and microstructure of alkali-activated fly ash-based geopolymers

    Microsoft Academic Search

    Alexandre Silva de Vargas; Denise C. C. Dal Molin; Antônio C. F. Vilela; Felipe José da Silva; Bruno Pavão; Hugo Veit

    2011-01-01

    Fly ashes (FA) are byproducts of electricity production from mineral coal in thermoelectric power plants. The pozzolanic properties of FA have been utilized in various applications, including structural concrete, yet the large part of FA is still discarded into the environment. To promote greater FA usage, this study aims to produce a dense matrix, with mechanical properties satisfactory for civil

  8. Ionic conductivities of Nasicon-type glass-ceramic superionic conductors in the system Na 2O–Y 2O 3–XO 2–SiO 2 (X = Ti, Ge, Te)

    Microsoft Academic Search

    Toshinori Okura; Mitsugu Saimaru; Hideki Monma; Kimihiro Yamasita

    2009-01-01

    Glass-ceramics of the titanium-, germanium- or tellurium-containing Na5RSi4O12-type (R=rare earth; Y) Na+-superionic conductors (N5YXS) were prepared by crystallization of glasses with the composition Na3+3xY1?xXySi3?yO9 (X=Ti; NYTiS, Ge; NYGeS, X=Te; NYTeS), and the effects of X elements on the separation of the phase and the microstructural effects on the conduction properties of glass-ceramics were discussed. The combination of x and y

  9. Nickel speciation in multi-oxydes components silicate glasses: new UV-VIS-NIR spectroscopic results and geochemical implications

    NASA Astrophysics Data System (ADS)

    Antoine, Bénard; Laurence, Galoisy; Georges, Calas

    2010-05-01

    Silicate glasses are usually considered as good analogues for natural melts and thus frequently synthesized to study their structural properties. The optical spectra of Nickel are well constrained in crystal phases [1]. Only recent studies permit real advances of Ni speciation in glasses [2, 3]. In alkali and alkaline-earth silicate glasses, Ni2+is always found as predominantly [5]Ni2+ with some minor [4]Ni2+, whereas in borosilicate and borate glasses with the same network modifying cations, Nickel could be observed as [4]Ni2+, [5]Ni2+ and/or [6]Ni2+, depending on the glass composition and especially on the proportion and nature of alkali/ alkaline-earth cations. The short-range structure of a new large compositional range of Ni-doped (1000 ppm) multi-oxides silicate glasses has been investigated by UV-VIS-NIR spectroscopy. The glasses were synthesized to study the separate and combined influences of alkali (K, Na), alkaline-earth elements (Ca, Mg) and Al on Ni speciation. First, our spectral results on non-magnesian system confirm a high [4]Ni2+ content in silico-potassic (11.5 to 28.7 wt.% K2O) glasses compared to the predominance of [5]Ni2+ (± [4]Ni2+) in purely silico-sodic glasses (15 to 27.5 wt.% Na2O) and a mixing of variable proportions of [4]Ni2+ and [5]Ni2+ in mixed chemical compositions (Si-K-Ca and Si-Na-Ca with each element varying independently from ~10 to ~25 wt.%). Mixed Si-K-Ca glasses (fixed ~10 wt.% K2O and 9.1 to 26.4 wt.% CaO) show significant [5]Ni2+ spectral band appearance with the increase of Ca concentration. At constant Ca (~10 wt.% CaO) and variable K (14.3 to 29.7 wt.% K2O), [4]Ni2+ spectral band intensities remain predominant. Na rich silicate glasses always favor [5]Ni2+while, for high K concentration, Ni2+ is mainly found as [4]Ni2+. This behaviour of Ni2+ as a function of glass composition is coherent with [4]Ni2+ being predominant in presence of large charge compensating, low field strength cations such as K. In that case, Ni2+ is found in network forming position but does not take that role because of its low charge as compared to network forming cations such as Si4+. With higher field strength cations such as Ca or Na, Ni2+is mostly found as network modifier. Al3+ ? Si4+ substitution (15 wt.% Al2O3) in alkali-alkaline earth systems show clear decrease of [4]Ni2+ spectral band intensities revealing preferential use of Na+ and Ca2++ Na+ to charge compensate oxygen anions associated to Al3+. This reveals the importance of the competition between cations for the charge compensating effect. [6]Ni2+ in glasses has only been observed in borate ones with low alkali content [4]. Our results on the structural investigation of pseudo-basaltic magnesian glasses (CMNAS system with 7 to 20 wt.% MgO) show first evidences of combined presence of [6]Ni2+, [5]Ni2+ and [4]Ni2+ in purely silicate glasses. The presence of the 3A2g(F) - 3T2g(P) electronic transition on the optical spectra of the investigated glasses allow identification of [6]Ni2+. The intensity of the band corresponding to this transition increases at the expense of the [5]Ni2+ band in relation with the increase of the MgO content of the glass. The discovery of the MgO addition effect on Ni coordination with the appearance of [6]Ni2+ gives new insights on the olivine-liquid partitioning of Ni. According to our results, the resulting effect would be an increase affinity of Ni for a melt with high MgO content, considering the glass to be a snapshot of the liquid structure. This could explain, the partition coefficient (DNiol-liq) decrease coupled with the increase of the MgO content of the equilibrium melt observed in several experimental studies [5]. [1] Burns, Mineralogical Applications of crystal field theory, Cambridge University Press, 1993. [2] Galoisy, L. & Calas, G., 1993a, Structural environment of Nickel: Part 1. Spectroscopic determination of coordination states, Geochem. Cosmochim. Acta., 57, 3613 - 3626. [3] Galoisy L., Calas G., Cormier L., Marcq B and Thibault M.H., 2005, Overview of the environment of Ni in oxide

  10. The age and origin of felsic intrusions of the Thetford Mines ophiolite, Quebec.

    USGS Publications Warehouse

    Clague, D.A.; Frankel, C.S.; Eaby, J.S.

    1985-01-01

    This ophiolite was obducted in the early Ordovician during the closing of the proto-Atlantic. The tectonized peridotite of the lower unit of the ophiolite is intruded by felsic dykes and pods, including isolated lenses of massive rodingite, small bodies of strongly deformed diorite, and younger, less deformed monzonite. These intrusions are found only near the base of the ophiolite, and are considered to have been emplaced before the ophiolite reached its present position. The young group of intrusions consists of biotite-muscovite quartz monzonite and leuco-quartz monzonite. Analysed samples have high K2O, high (K2O X 100)/Na2O + K2O) ratios, and high initial Sr ratios, indicating that the magma source was continental and that these felsic rocks formed by partial melting of continental sediments. Whole-rock and mineral isochron ages suggest that the felsic intrusions are approx 456 + or - 4 m.y. old and that they were metamorphosed approx 418 + or - 7 m.y. ago. The detachment of the ophiolite occurred approx 491 + or - 3 m.y. ago. The felsic dykes were intruded approx 35 m.y. later, during the Taconic orogeny. The lengthy time between detachment and final nappe emplacement recorded by the felsic dykes may be a requirement for formation of abundant asbestiform chrysotile. Whole-rock analyses (16) and Rb, Sr and 87Sr/86Sr data from the Colline de Granite, King Mts., Vimy Ridge and Black Lake samples are presented.-P.Br.

  11. Reaction of sodium calcium borate glasses to form hydroxyapatite.

    PubMed

    Han, Xue; Day, Delbert E

    2007-09-01

    This study investigated the transformation of two sodium calcium borate glasses to hydroxyapatite (HA). The chemical reaction was between either 1CaO . 2Na(2)O . 6B(2)O(3) or 2CaO . 2Na(2)O . 6B(2)O(3) glass and a 0.25 M phosphate (K(2)HPO(4)) solution at 37, 75 and 200 degrees C. Glass samples in the form of irregular particles (125-180 microm) and microspheres (45-90 and 125-180 microm) were used in order to understand the reaction mechanism. The effect of glass composition (calcium content) on the weight loss rate and reaction temperature on crystal size, crystallinity and grain shape of the reaction products were studied. Carbonated HA was made by dissolving an appropriate amount of carbonate (K(2)CO(3)) in the 0.25 M phosphate solution. X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy were used to characterize the reaction products. The results show that sodium calcium borate glasses can be transformed to HA by reacting with a phosphate solution. It is essentially a process of dissolution of glass and precipitation of HA. The transformation begins from an amorphous state to calcium-deficient HA without changing the size and shape of the original glass sample. Glass with a lower calcium content (1CaO . 2Na(2)O . 6B(2)O(3)), or reacted at an elevated temperature (75 degrees C), has a higher reaction rate. The HA crystal size increases and grain shape changes from spheroidal to cylindrical as temperature increases from 37 to 200 degrees C. Increase in carbonate concentration can also decrease the crystal size and yield a more needle-like grain shape. PMID:17486301

  12. Petrological and geochemical constraints on the origin of mafic dykes intruding the composite Kaçkar Pluton from the eastern Blacksea magmatic arc, NE Turkey

    NASA Astrophysics Data System (ADS)

    Aydin, Faruk; Oguz, Simge; Baser, Rasim; Uysal, Ibrahim; Sen, Cüneyt; Karsli, Orhan; Kandemir, Raif

    2015-04-01

    Geological, petrographical and geochemical data of mafic dykes intruding the composite Kaçkar Pluton from the eastern Blacksea magmatic arc (EBMA), NE Turkey, provide new insights into the nature of the metasomatizing agents in subcontinental lithospheric mantle beneath the region during the late Mesozoic-early Tertiary. Mafic dykes from the Çaykara and Hayrat (Trabzon), and also Ikizdere (Rize) areas from the northern margin of the EBMA consist of basalts, dolerites, lamprophyres (basic member) and lesser basaltic andesites and trachyandesites (evolved member). All dykes have no deformation and metamorphism. The outcrops of these dykes vary, with thickness from 0.2 to 10 m. and visible length from 3 to 20 m. In general, the mafic dykes dip steeply and cut directly across the Kaçkar Pluton, and show NW- and NE-trending, roughly parallel to the orientations of the EBMA main faults. Most of the dyke samples display subaphyric to porphyritic texture with phenocrysts of plagioclase (up to 10%), clinopyroxene (5-20%), amphibole (5-15%), and some contain variable amount of biotite (5-20%), lesser quartz (1-2%), and minor euhedral zircon, apatite and Fe-Ti oxides. The basic members of the mafic dykes have SiO2 of 44.1-51.9%, MgO of 4.5-12.1%, and TiO2 >mostly 0.8% (up to 2.3%) with K2O+Na2O of 1.3-6.6% with mostly subalkaline character. They are relatively high in mg-number (0.45-0.73) and transition metals (V=171-376 ppm, Co=22-45 ppm, Ni=3-148 ppm, and Sc=21-49 ppm). The evolved members of the dykes exhibit relatively higher SiO2 (57.1-60.2%) and K2O+Na2O (5.6-9.0%), and lower MgO (2.2-5.9%) and TiO2 (0.5-0.8%) contents than those from the basic dykes. Also, these samples have slightly low mg-number (0.41-0.65) and transition metals (V=99-172 ppm, Co=9-22 ppm, Ni=1-43 ppm, and Sc=9-20 ppm). In the Harker diagrams, all samples of the mafic dykes form a continuous array, and exhibit similar geochemical characteristics. In general, SiO2 inversely correlates with MgO, Fe2O3t, TiO2, CaO and P2O5. Transition metals (Ni, Co, Sc) drastically decrease with decreasing SiO2. Such characteristics support fractionation of Ol+Cpx+Amp+Fe-Ti oxides+Apatite from parental magmas. On the chondrite-normalized REE patterns, the all samples are enriched in LREEs, and show variable LREE/HREE fractionation ((La/Yb)N=0.8-22.2) with slightly negative Eu anomalies (Eu/Eu*=0.7-1.3). On the N-MORB normalized diagrams, the samples from both dyke members are generally enriched in LILEs and depleted in HFSEs. They are also characterized by subparallel patterns with pronounced depletion of Nb and Ti. Slightly negative Eu anomaly and negative Sr anomaly in the spider diagram for some samples may be attributed to fractionation of plagioclase. Depletion in Nb and Ti, and negative correlation between P2O5, TiO2 and SiO2 are likely related to amphibole, Fe-Ti oxides and apatite fractionation. The LILE and LREE enrichment and HFSE depletion suggest that the mantle source of the mafic dyke samples has compositional similarity with metasomatized mantle wedge. High La/Nb (2-8), Ba/Nb (20-850) and Zr/Nb ratios (5-41) in the mafic dyke samples are clearly distinctive to the features for most intraplate volcanic rocks (La/Nb=0.5-2.5, Ba/Nb=1-20 and Zr/Nb

  13. The Comparative Structural Study of Vitreous Matrices P{sub 2}O{sub 5}centre dotMeO [MeO ident to Li{sub 2}O (M{sub 1}) or CaO (M{sub 2})] Systems and {sub x}Fe{sub 2}O{sub 3}(100-x)[P{sub 2}O{sub 5}centre dotMeO] Glasses by Raman Spectroscopy

    SciTech Connect

    Andronache, C. [Department of Physics, North University of Baia Mare, Str. Victoriei nr. 76, RO-431122, Baia Mare (Romania)

    2010-01-21

    For getting information about the way in which the structural units presented in glass matrices P{sub 2}O{sub 5}centre dotLi{sub 2}O (M{sub 1}) and P{sub 2}O{sub 5}centre dotCaO (M{sub 2}) are modifying with the substitutions Li{sub 2}O with CaO, these glasses where investigated by Raman spectroscopies. The absorption bands obtained and their assignments for each those two matrices are summarized. The influence of Fe{sub 2}O{sub 3} content on the structure of M1 and M2 matrices was followed.

  14. Preparation and properties of glass-ceramic materials obtained by recycling goethite industrial waste

    Microsoft Academic Search

    M. PELINO; C. CANTALINI; J. M A. RINCON

    1997-01-01

    The recycling of toxic goethite waste, originated in the hydrometallurgy of zinc ores, in glass-ceramic matrices has been\\u000a studied. Oxide compositions suitable to form glasses were prepared by mixing the goethite waste with granite scraps and glass\\u000a cullet, yielding the following oxide composition (wt%): SiO2, 44.6; Al2O3, 3.3; Fe2O3, 25.5; MgO, 1.6; CaO, 4.5; Na2O, 5.9; PbO, 3.1; ZnO, 6.5;

  15. Structural characterization by x-ray methods of novel antimicrobial gallium-doped phosphate-based glasses

    NASA Astrophysics Data System (ADS)

    Pickup, D. M.; Moss, R. M.; Qiu, D.; Newport, R. J.; Valappil, S. P.; Knowles, J. C.; Smith, M. E.

    2009-02-01

    Antimicrobial gallium-doped phosphate-based glasses of general composition (P2O5)0.45(CaO)0.16(Na2O)0.39-x(Ga2O3)x (where x =0, 0.01, 0.03, and 0.05) have been studied using the advanced synchrotron-based techniques of Ga K-edge x-ray absorption spectroscopy and high-energy x-ray diffraction to provide a structural insight into their unique properties. The results show that the Ga3+ ions are octahedrally coordinated. Furthermore, substitution of Na2O by Ga2O3 strengthens the phosphate network structure because the presence of GaO6 octahedra inhibits the migration of the remaining Na+ ions. The results are discussed in terms of the use of Na2O-CaO-P2O5 glasses as controlled-delivery devices for antimicrobial Ga3+ ions in biomedical applications. We are thereby able to relate the atomic-scale environment of the Ga3+ ions beneficially to the glass dissolution, and thus to their ability to disrupt bacterial cell activity by usurping the role of iron.

  16. Structural characterization by x-ray methods of novel antimicrobial gallium-doped phosphate-based glasses.

    PubMed

    Pickup, D M; Moss, R M; Qiu, D; Newport, R J; Valappil, S P; Knowles, J C; Smith, M E

    2009-02-14

    Antimicrobial gallium-doped phosphate-based glasses of general composition (P(2)O(5))(0.45)(CaO)(0.16)(Na(2)O)(0.39-x)(Ga(2)O(3))(x) (where x=0, 0.01, 0.03, and 0.05) have been studied using the advanced synchrotron-based techniques of Ga K-edge x-ray absorption spectroscopy and high-energy x-ray diffraction to provide a structural insight into their unique properties. The results show that the Ga(3+) ions are octahedrally coordinated. Furthermore, substitution of Na(2)O by Ga(2)O(3) strengthens the phosphate network structure because the presence of GaO(6) octahedra inhibits the migration of the remaining Na(+) ions. The results are discussed in terms of the use of Na(2)O-CaO-P(2)O(5) glasses as controlled-delivery devices for antimicrobial Ga(3+) ions in biomedical applications. We are thereby able to relate the atomic-scale environment of the Ga(3+) ions beneficially to the glass dissolution, and thus to their ability to disrupt bacterial cell activity by usurping the role of iron. PMID:19222291

  17. Electrical behaviour of Li 2O–ZnO–SiO 2 glass and glass-ceramics system

    Microsoft Academic Search

    M. Goswami; S. K. Deshpande; R. Kumar; G. P. Kothiyal

    2010-01-01

    Sealing quality lithium zinc silicate (LZS) glasses of compositions (wt.%) (a) LZSL– Li2O: 12.65, ZnO: 1.85, SiO2: 74.4, Al2O3: 3.8, K2O: 2.95, P2O5: 3.15, B2O3: 1.2 (low ZnO), and (b) LZSH– Li2O: 8.9, ZnO: 24.03, SiO2: 53.7, Na2O: 5.42, P2O5: 2.95, B2O3: 5 (high ZnO) were prepared by conventional melt-quench technique and converted to glass-ceramics by controlled crystallization process. The

  18. Bioactive glass coatings for orthopedic metallic implants

    SciTech Connect

    Lopez-Esteban, Sonia; Saiz, Eduardo; Fujino, Sigheru; Oku, Takeo; Suganuma, Katsuaki; Tomsia, Antoni P.

    2003-06-30

    The objective of this work is to develop bioactive glass coatings for metallic orthopedic implants. A new family of glasses in the SiO2-Na2O-K2O-CaO-MgO-P2O5 system has been synthesized and characterized. The glass properties (thermal expansion, softening and transformation temperatures, density and hardness) are in line with the predictions of established empirical models. The optimized firing conditions to fabricate coatings on Ti-based and Co-Cr alloys have been determined and related to the glass properties and the interfacial reactions. Excellent adhesion to alloys has been achieved through the formation of 100-200 nm thick interfacial layers (Ti5Si3 on Ti-based alloys and CrOx on Co-Cr). Finally, glass coatings, approximately 100 mu m thick, have been fabricated onto commercial Ti alloy-based dental implants.

  19. Sodium metasomatism along the Melones fault zone, Sierra Nevada foothills, California, USA

    USGS Publications Warehouse

    Albino, G.V.

    1995-01-01

    Albitite, locally aegirine- and riebeckite-bearing, formed as a result of sodium metasomatism of felsic dykes and argillites along the Melones Fault Zone near Jamestown, California. Pyrite, magnetite, hematite and titanite are common in small amounts in altered dykes. The dykes were originally plagioclase-hornblende porphyritic, and had major and trace element abundances typical of calc-alkaline rocks, whereas they now have Na2O contents as high as 11.40%. Mass balance calculations indicate that alteration involved addition of large amounts of sodium, and the removal of SiO2 and K2O. Textural preservation, combined with volume factors calculated from specific gravity and whole rock analytical data, indicate that Na-metasomatism was essentially isovolumetric. -from Author

  20. Chemical Analyses of Pre-Holocene Rocks from Medicine Lake Volcano and Vicinity, Northern California

    USGS Publications Warehouse

    Donnelly-Nolan, Julie M.

    2008-01-01

    Chemical analyses are presented in an accompanying table (Table 1) for more than 600 pre-Holocene rocks collected at and near Medicine Lake Volcano, northern California. The data include major-element X-ray fluorescence (XRF) analyses for all of the rocks plus XRF trace element data for most samples, and instrumental neutron activation analysis (INAA) trace element data for many samples. In addition, a limited number of analyses of Na2O and K2O by flame photometry (FP) are included as well assome wet chemical analyses of FeO, H2O+/-, and CO2. Latitude and longitude location information is provided for all samples. This data set is intended to accompany the geologic map of Medicine Lake Volcano (Donnelly-Nolan, in press); map unit designations are given for each sample collected from the map area.

  1. Zur chemie der marsoberfla??che - Mineralogische und petrologische Implikationen

    USGS Publications Warehouse

    Keil, K.; Clark, B.C.; Baird, A.K.; Toulmin, P., III; Rose, H.J., Jr.

    1978-01-01

    Analyses of 13 samples of Martian surface materials with the Viking X-ray fluorescence spectrometers show SiO2 similar to that of terrestrial mafic rocks, whereas Fe2O3, Cl, and S are higher and Al2O3, K2O, Rb, Sr, Y, and Zr are lower. Low totals suggest presence of CO2, H2O, and Na2O. Duricrust fragments are higher in S than fines, but samples from both landing sites are surprisingly similar. We suggest that Martian surface materials are aeolian deposits of complex mixtures of weathering products of maficultramafic rocks, possibly consisting of iron-rich clays, sulfates, iron oxides, carbonates, and chlorides. ?? 1978 Springer-Verlag.

  2. Search for solid conductors of Na(+) and K(+) ions: Five new conductors

    NASA Technical Reports Server (NTRS)

    Singer, J.; Kautz, H.; Fielder, W. L.; Fordyce, J.

    1975-01-01

    Five conductors of three structure types were discovered which, as solids, can transport Na(+) or K(+) ions with conductivities of approximately .00001/(omega cm) at 300 K. These compounds are: (1) the pyrochlores NaTaWO6 and NaTa2O5F, both with an activation energy for conduction delta E of 21 kJ/mole; (2) the bodycentered cubic form of NaSbO3, with delta E = 42 kJ/mole; and (3) the niobates 2Na2O with 3Nb2O5 and 2K2O with 3Nb2O5, with the alkali ions probably in open layers of the incompletely determined structure; delta E = 17 kJ/mole. On the basis of approximately 40 structure types, some generalizations were made regarding the relation between structure and ionic transport.

  3. The relationship of the lunar regolith less than 10-microns fraction and agglutinates. II - Chemical composition of agglutinate glass as a test of the 'fusion of the finest fraction' /F3/ model

    NASA Technical Reports Server (NTRS)

    Walker, R. J.; Papike, J. J.

    1982-01-01

    Agglutinate glasses from nine Apollo soils have been studied using an automated electron microprobe technique in order to test the fusion of the finest fraction model proposed by Papike (1981). The nine average agglutinate glass compositions are compared with the calculated fused-soil-free compositions, the bulk compositions and the 90-20 micron fraction compositions of the soils in which they are found. It is found that the agglutinate glass data are consistent with the composition of most of the fractions finer than 10 microns, allowing for the volatile loss of K2O and Na2O; some inconsistencies that do arise may result from the degree of soil maturity and the amount of material finer than 10 microns. It is concluded that the fusion of the finest fraction model is a good first approximation of mechanisms affecting the formation of agglutinate glass.

  4. Voronkovite, Na15(Na,Ca,Ce)3(Mn,Ca)3Fe3Zr3Si26O72(OH,O)4Cl · H2O, a new mineral species of the eudialyte group from the Lovozero alkaline pluton, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Khomyakov, A. P.; Nechelyustov, G. N.; Rastsvetaeva, R. K.

    2009-12-01

    This paper describes a new member of the eudialyte group named in honor of Alexander Alexandrovich Voronkov (1928-1982), the prominent Russian crystallographer. The new mineral has been found in the Shkatulka hyperalkaline pegmatite body at Mt. Alluaiv, Lovozero alkaline pluton, Kola Peninsula, Russia. The mineral is associated with microcline, sodalite, nepheline, aegirine, terskite, lomonosovite, vuonnemite, shkatulkalite, manganoneptunite, and sphalerite. Voronkovite occurs as rounded, poorly faced crystals up to 2-5 mm across. The new mineral is light brown, with vitreous luster and conchoidal fracture. The streak is white. Voronkovite is transparent and brittle; the Mohs hardness is 5; cleavage or parting is not observed. D(meas) = 2.97(2) g/cm3 (volumetric method); D(calc) = 2.95 g/cm3. The new mineral is uniaxial, positive, pleochroic from lemon yellow along X to brownish pink along Y, and is not luminescent in UV light. Voronkovite easily dissolves and gelates in acid at room temperature. The new mineral is trigonal, space group R3, a = 14.205(7), c = 30.265(15) Å, V = 5289(8) Å3, Z = 3. The strongest reflections in the X-ray diffraction pattern [ d, Å ( I)( hkl)] are 2.970(100)(315), 4.316(85)(205), 2.848(84)(404), 3.221(43)(208), 3.536(41)(027), 3.039(41)(119). The chemical composition (electron microprobe, H2O determined with chemical analysis) is as follows, wt %: 15.84 Na2O, 0.28 K2O, 3.08 CaO, 1.76 SrO, 4.65 MnO, 3.53 FeO, 0.93 La2O3, 1.36 Ce2O3, 0.68 Nd2O3, 0.15 Al2O3, 49.48 SiO2, 0.33 TiO2, 14.11 ZrO2, 0.23 HfO2, 0.91 Nb2O5, 0.44 Cl, 0.21 F, 1.56 H2O, 0.19 -O = (Cl,F)2; total is 99.34. The empirical formula calculated on the basis of Si + Al = 26 ( Z = 3) is as follows: (Na13.96Sr0.54K0.19)?14.69(Na1.64Ca0.92Ce0.26 La0.18)?3.00(Mn2.06Ca0.81Nd0.13)?3.00(F1.54Zr0.60Na0.48Nb0.21Ti0.13Hf0.04)?3.00Zr3.00(Si1.91Al0.09)?2.00(Si24O72)[(OH)2.98 O1.02]?4(Cl0.39F0.35)?0.74 · 1.23H2O. The simplified formula is Na15(Na,Ca,Ce)3(Mn,Ca)3Fe3Zr3Si26O72(OH,O)4Cl · H2O. The IR spectrum of the mineral and description of its crystal structure are given. The position of voronkovite in the crystallochemical taxonomy of eudialyte group is discussed, and the relationship to other members, oneillite and raslakite, are characterized. The type material is deposited at the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.

  5. Chemical composition and mineralogy of borate from Rio Grande deposit, Uyuni (Bolivia) as raw materials for industrial applications

    NASA Astrophysics Data System (ADS)

    Guillen Vargas, Julio; Arancibia, Jony Roger Hans; Alfonso, Pura; Garcia-Valles, Maite; Parcerisa, David; Martinez, Salvador

    2014-05-01

    Bolivia has large tailings as a result of the historic and present-day Sn mining activity developed extensively in that country. Tailings produced in these mining activities have an appropriate composition to reprocess them and make silicate glass and glass-ceramics, obtaining the valorization of wastes and reducing the visual and chemical impact. Reprocessing the wastes to make glass and glass-ceramics prevents the leaching of heavy metals from those wastes because they are retained in the structure of the glass. Furthermore, an option to increase the economic value of these glasses is the introduction of boron and other additives to produce borosilicate glass. In this study a characterization of the Rio Grande borate deposit for its use in the manufacture of borosilicate glass is presented. Mineralogy was determined by X-ray diffraction (XRD), and Fourier transforms infrared spectroscopy (FTIR); textures were observed by scanning electron microscopy (SEM) and chemical composition was determined by inductively coupled plasma mass spectrometry (ICP-MS). The Rio Grande borate deposit is located in an area of about 50 km2 close to the south of the Salar of Uyuni, in the Río Grande de Lípez Delta. Borates occur in the contact between fluvio-deltaic and lacustrine sediments from water raising the surface by capillarity. The borates crop out in an extent area but towards the west they are covered by fluvio-deltaic sediments, which can be up to 2 m thick. These borates occur as lenses 50-100 m in diameter and layers up to 1 m thick. They usually form brittle nodules with a cotton-ball texture. Chemical composition of the Rio Grande borates is CaO, 11.82-13.83 wt%; Na2O, 13.50-19.35 wt%; K2O, 0.05- 1.04 wt%; MgO, 0.42-1.46 wt%; B2O3, 36.21-42.60 wt%; SiO2, up to 0.53 wt% and SO2, up to 0.60 wt%. Trace elements are low: Sr content is between 151-786 ppm, Al 12-676 ppm, Mn between 1-17 ppm, As 2-10 ppm and Fe between 9-376 ppm. The most abundant borate mineral in this deposit is ulexite (NaCaB5.5H20), halite can reach up to 17 wt% and gypsum up to 1.2 wt.%. Calcite occurs in minor contents. Ulexite exhibits a fibrous morphology with fibers oriented parallel each other. Purity of borates from the Rio Grande deposits makes them suitable for the most restrictive applications. Chemistry of these borates is in accordance with the necessary composition for obtaining borosilicate glasses. Acknowledgements: This work was partly financed by the project AECID: A3/042750/11, and the SGR 2009SGR-00444.

  6. Mineral chemistry and geochemistry of the Late Neoproterozoic Gabal Abu Diab granitoids, Central Eastern Dessert, Egypt: Implications for the origin of rare metal post-orogenic A-type granites

    NASA Astrophysics Data System (ADS)

    Sami, Mabrouk; Ntaflos, Theodoros; Farahat, Esam S.; Ahmed, Awaad F.; Mohamed, Haroun A.

    2015-04-01

    The Neoproterozoic Gabal Abu Diab pluton is a part of the Arabian Nubian shield (ANS) continental crust and located in the Central Eastern Desert (CED) of Egypt. It constitutes multiphase granitic pluton intruded into granodiorite and metagabbro-diorite rocks with sharp and nonreactive contacts. Based on field observations, colors, structural variations and petrographic investigations, this granitic outcrop consists of an inner core of two-mica granite (TMG) followed outward by garnet bearing muscovite granite (GBMG) and albite granite (AG). Petrographical study indicated that medium to coarse-grained TMG is dominated by K-feldspar (Or88-98), quartz, plagioclase (albite, An0-7), muscovite and biotite with hypidiomorphic texture. With exception the appearance of garnet and the disappearance of biotite the GBMG resembles the TGM, while AG is leucocratic without any mafic mineral. The main accessories are zircon, Nb and Ta-bearing rutile, columbite, ilmenorutile, ilmenite, magnetite and apatite. This mineralogical similarity and the existence of columbite group minerals (CGM) in all granitoids, indicates a cogenetic relationship. Microprobe analyses reveal that, besides the CGM, rutile and ilmenite are the main repository phases for Nb-Ta-Ti. Columbite-(Mn) exists as individual subhedral crystals (up to 100?m in size) or intimate intergrowth with Nb-bearing rutile and/or ilmenite. The CGM are represented mostly by columbite-(Mn) with Ta/(Ta+Nb) and Mn/(Mn+Fe) ratio ranging from 0.02-0.08 and 0.4-0.9, respectively suggesting extreme degree of magmatic fractionation. Rutile contains significant amounts of Ta (up to 4 wt.% Ta2O5) and Nb (up to 22 wt.% Nb2O5). Biotites are phlogopite-annite in composition (Ann47-60Phlog40-53,on average) and are enriched with AlIV that characterize peraluminous granites. Garnets contain 60-69 mol.% spessartine and 28-36 mol.% almandine where, the ratio of spessartine and almandine together exceeds 95 mole percent, similar to garnet occur within A-type granite worldwide. According to Zhang et al., 2012, the garnet crystallized at the expense of biotite from the MnO-rich evolved melt after fractionation of biotite, plagioclase, K-feldspar, zircon, apatite, and ilmenite. The granitoids are alkali feldspar granites showing distinct geochemical features and most likely, belong to the post-orogenic younger Egyptian granitoids. They are peraluminous A-type alkaline rocks but they have lower Fe2O3, MgO, MnO, CaO, TiO2, P2O5, Sr, Ba, V, and higher SiO2, Na2O, K2O, Nb, Ta, U, Zr, Th, Ga/Al and Rb than the typical rocks of this type. The positive correlation between Ba and Sr, and the negative correlation between Rb and K/Rb reveal fractional crystallization of alkali feldspar. The similarity in most geochemical characteristics suggests that Abu Diab granitoids are genetically related to each other and extremely enrichment in incompatible elements such as Nb and Ta, indicating that they crystallized from extremely differentiated magmas. References: Zhang, J., Ma, C. and She, Z., 2012. An Early Cretaceous garnet-bearing metaluminous A-type granite intrusion in the East Qinling Orogen, central China: Petrological, mineralogical and geochemical constraints. Geoscience Frontiers 3 (5), 635-646.

  7. The Origin and Evolution of a Diverse Suite of Late Pleistocene Andesitic to Dacitic Lavas From the Northern Cascade arc at Mt. Baker, Washington.

    NASA Astrophysics Data System (ADS)

    Baggerman, T. D.; Debari, S.

    2007-12-01

    Mt. Baker, a dominantly andesitic stratovolcano, is located in the northernmost segment of the Cascade magmatic arc. The origin and evolution of andesites in the northern Cascades has thus far not been explored in any systematic way. This study highlights the geochemical diversity of andesites erupted from Mt. Baker and describes processes that are responsible for the generation of this dominant intermediate lava type. Presented here are petrographic observations, mineral chemistry, major oxide concentrations, and the largest trace and REE data set to date for three Late Pleistocene and Holocene lava flows from Mt. Baker: the basaltic andesite of Sulphur Creek (52.5-57.6 wt.% SiO2, 4.7-5.5 wt.% MgO), the andesite of Glacier Creek (59.5-63.3 wt.% SiO2, 4.7-5.0 wt.% MgO), and the andesite and dacite of Boulder Glacier (60.5-64.1 wt.% SiO2, 2.1-3.5 wt.% MgO). The data are used to characterize and asses the relationship between the three flows. The three lava flows are classified as medium K, and to a lesser degree, high K, calc-alkaline basalts through dacites. Major oxide concentrations for Sulphur Creek and Boulder Glacier lavas form curvilinear trends with increasing SiO2. The andesite of Glacier Creek has distinct major oxide chemistry, with elevated concentrations of MgO and CaO and lower concentrations of Na2O and K2O for a given wt.% SiO2 relative to the major oxide trends of the other lavas. Glacier Creek lavas also show enrichment of Ni, Cr, and Sr and depletion in La, Nb, Ta, Zr and Y. REE patterns and slopes are distinct for each flow, but are not correlated with degree of differentiation. The mafic lavas of Sulphur Creek have the highest REE abundances relative to the other lavas, with the lowest La/Yb (~4.5). The Glacier Creek andesites have the lowest REE abundances and the largest La/Yb (~6.7). The Boulder Glacier andesites and dacites have intermediate REE abundances relative to the other lavas with intermediate La/Yb (~6.4). All lavas display disequilibrium textures such as magmatic reaction and resorption textures, sieved textures and complicated chemical zoning patterns typical of magma mixing and complicated fractionation processes. Major and trace element fractionation modeling of the mafic lavas of Sulphur Creek fail to produce the higher MgO values in the more differentiated Glacier Creek lavas, and the steeper and relatively depleted REE abundances in both the Glacier Creek and Boulder Glacier lavas. The above data and petrographic observations, coupled with major and trace element fractionation modeling, suggest that the generation of these chemically distinct andesites requires multiple mantle sources that have been modified by crustal processes. These processes include magma mixing and/or complicated crystal fractionation processes.

  8. Archean Arctic continental crust fingerprints revealing by zircons from Alpha Ridge bottom rocks

    NASA Astrophysics Data System (ADS)

    Sergeev, Sergey; Petrov, Oleg; Morozov, Andrey; Shevchenko, Sergey; Presnyakov, Sergey; Antonov, Anton; Belyatsky, Boris

    2015-04-01

    Whereas thick Cenozoic sedimentary cover overlapping bedrock of the Arctic Ocean, some tectonic windows were sampled by scientific submarine manipulator, as well as by grabbing, dredging and drilling during «Arctic-2012» Russian High-Arctic expedition (21 thousands samples in total, from 400-km profile along Alpha-Mendeleev Ridges). Among others, on the western slope of Alpha Ridge one 10x10 cm fragment without any tracks of glacial transportation of fine-layered migmatitic-gneiss with prominent quartz veinlets was studied. Its mineral (47.5 vol.% plagioclase + 29.6% quartz + 16.6% biotite + 6.1% orthoclase) and chemical composition (SiO2:68.2, Al2O3:14.9, Fe2O3:4.44, TiO2:0.54, MgO:2.03, CaO:3.13, Na2O:3.23, K2O:2.16%) corresponds to trachydacite vulcanite, deformed and metamorphozed under amphibolite facies. Most zircon grains (>80%) from this sample has an concordant U-Pb age 3450 Ma with Th/U 0.8-1.4 and U content of 100-400 ppm, epsilon Hf from -4 up to 0, and ca 20% - ca 3.3 Ga with Th/U 0.7-1.4 and 90-190 ppm U, epsilon Hf -6.5 to -4.5, while only 2% of the grains show Proterozoic age of ca 1.9 Ga (Th/U: 0.02-0.07, U~500 ppm, epsilon Hf about 0). No younger zircons were revealed at all. We suppose that magmatic zircon crystallized as early as 3450 Ma ago during acid volcanism, the second phase zircon crystallization from partial melt (or by volcanics remelting) under amphibolite facies metamorphism was at 3.3 Ga ago with formation of migmatitie gneisses. Last zircon formation from crustal fluids under low-grade metamorphic conditions was 1.9 Ga ago. There are two principal possibilities for the provenance of this metavolcanic rock. The first one - this is ice-rafted debris deposited by melted glacial iceberg. However, presently there are no temporal and compositional analogues of such rocks in basement geology of peri-oceanic regions, including Archean Itsaq Gneiss Complex, Lewisian Complex and Baltic Shield but these regions are far from the places of nowadays iceberg formation. Moreover, no Grenvillian-age zircons were revealed in studied sample. The nearest areas of Paleo- and Mesoarchean rocks appearance are deeply inland territories like Acasta Gneiss Complex, Uivak Gneisses, the Superior Province, Anabar and Aldan Shields, Northern China craton (Anshan complex), thus, a only possibility to bring some fragments of basement rocks from these areas to oceanic coast is transcontinental river transportation. The second possibility - this gneissic clast has a local provenance and has undergone a submarine weathering, shallow marine avalanche, proximal transportation by alongside ocean flows, tidal waves abrasion, and as so, reflects local bedrock geology, i.e. adjacent Alpha Ridge rock composition. Additional confirmation of this can be seen in a wide distribution of Qu-sandstones with Paleo-Mezoarchean zircons, and finds of similar allochtonous zircons in dolerites along Alpha-Mendeleev Ridge profile. The studied fragment is a unique evidence for the possible existence of Paleoarchean continental crust within the submarine Alpha-Mendeleev Ridge in Arctic Ocean.

  9. Earth Based Views of Solute Profiles on Mars (Invited)

    NASA Astrophysics Data System (ADS)

    Amundson, R.

    2013-12-01

    'Historical accounts of planetary evolution are mostly written in stone' (1), but the last chapter of that history is embedded in its soil. Soil properties reflect the effects of prevailing environmental boundary conditions. Solute profiles are powerful indicators of the direction and magnitude of water flow. I briefly review the chemistry of salt profiles from deserts formed by upward vs. downward migrating water, use this as a basis for interpreting aspects of Mars hydrological history. The Noachian-aged Meridiani Planum land surface is exposed in the Endurance and Victoria Craters. These craters have been estimated to be ~ <10 My in age (2). During that time, wind erosion has sculpted the exposed walls, with possible secondary effects of moisture. The measurements by the MER Opportunity allow for an analysis of both post-excavation alteration of the craters and the pre-excavation alteration of the landscape by aqueous processes. Crater profiles include APXS 'asis' (fresh surface), brushed , and RAT'd samples. Using RAT'd samples as a baseline, the gains and losses of elements in the surficial samples can be assessed (Fig. 1). The calculations reveal similar trends of surface alteration within a crater (Victoria) and between two craters (Fig. 1). The asis samples are enriched in Na2O, Al2O3, CaO, and Br (and depleted in MgO, SO3, Cl, K2O, MnO, FeO) relative to the RAT'd material. Brushing drastically reduces these differences. These data show that the alteration is very surficial. The RAT'd samples appear to represent pre-impact chemical profiles of the sediment (Fig. 2). It has previously been reported that the upper ~1m at Victoria has been visibly altered by diagenesis (3). Both Endurance (4) and Victoria craters have remarkably similar depth profiles (relative to the lowest sampling point) of SO3, Cl, and Br. The salt profiles, combined with observations of physical alteration, suggest modest pedogenic alteration of the landsurface sometime prior to impact. The sequence of the SO3 and Cl is consistent only with downward aqueous transport, as clearly illustrated by comparison to Earth soils that form by groundwater evaporation vs. downward moving meteoric water. While the total water required to create the profiles is not easy to constrain, the meter scale depth of the alteration requires precipitation events well beyond mere surficial wetting. (1) Grotzinger et al. (2005). Earth and Planetary Science Letters 240:11-72. (2) Golombek, M.P. (2012) Timescale of small crater modification on Meridiani Planum, Mars. 43rd Lunar and Planetary Science Conference. (3) Arvidson et al. (2011). J. of Geophysical Research 116, E00F15, doi:10.1029/2010JE003746, 2011 (4) Amundson et al. (2008) Geochim. Cosmochim. Acta 72:3845-3864.

  10. Mineralogy and geochemistry of the IRG Misky gold deposit, southern Peru

    NASA Astrophysics Data System (ADS)

    Palacios, Silvia; Alfonso, Pura; Proenza, Joaquín Antonio

    2014-05-01

    The Misky gold deposit is one of the several Intrusion Related gold deposits that occur in the ocoña river basin, southern Peru. They are hosted in magmatic rocks from the Nazca-Palpa-Ocoña belt, from the Coastal Batholith. In this study, a petrologic and geochemical characterisation of the host rocks of the Misky deposit is presented to contribute to prove the deposit model. XRD, electron microscopy and electron microprobe analyses were used to characterize the ore and major and trace elements of host rocks were analysed by ICP-Ms. The Misky deposit, Cretaceous in age, consists mainly in quartz veins of lenticular morphology that can be more than 3 Km long and less than 1 m wide. At least two generations of magmatic host rocks are differentiated by the field relationships. The older generation is composed of plutonic rocks of the Incahuasi Unit constituted by diorites, quartz-monzonites, quartz-diorites and granodiorites in minor amounts. These rocks are crosscut by dykes of gabbro, tonalite and quartz diorite porphyries. Parallel to these dykes there is a NEE-SWW fault system. Gold veins are emplaced filling these fractures. Gabbro is rich in hornblende and present titanite reaction rims around ilmenite, which suggests relatively reduced conditions and high H2O contents. Hydrothermal alteration, associated with the gold mineralization, produced sericitization, chloritization and silicification in the surroundings of the veins. The Misky deposit has a Au-As-Pb-Zn-Cu association. Gold appears mainly in veins disseminationed in the host rocks near the contact with these veins. Gold occurs as enclosed grains within pyrite, or as electrum located in fractures of pyrite. In addition other sulphides as sphalerite, galena and chalcopyrite are abundant. Arsenopyrite, sulphosalts, bismuthinite and native bismuth also occur in lesser amounts. Calcocite, malachite and hematite are supergene minerals. The gold content can reach up to 130 pp Au and up to 0.6 wt% Cu. Major elements of the host rocks have a SiO2 content from 49.02 to 60.81 wt % and Al2O3 from 14.32 to 19.04 wt % (except one sample of 11.67 wt%. CaO can reach up to 9.34 wt%, Na2O up to 3.59 wt% and K2O up to 2.41 wt%. Geochemically these rocks are I-type calcalcaline and metaluminous. The Nb/Y and Y+Nb/Rb diagrams indicate that these host rocks are related to a volcanic arc-setting and formed in post-collision environment. Trace element patterns show LILE (K, Rb, Sr, Cs, Ba Be) and HFSE (Zr, Nb, Hf, Ta, Ti) depletion and enrichment for U, Th. Rocks from the late dykes are richer in REE. The chondrite normalised REE patterns show enrichment of the LREE and flattening of the HREE. Eu presents a positive anomaly for gabbro and diorite of the late dykes and does not show anomaly in the older rocks. Petrologic and geochemical characteristics of the host rocks of the Misky gold deposit are in accordance with the suitable setting for the intrusion gold related deposits.

  11. Günterblassite, (K,Ca)3 - x Fe[(Si,Al)13O25(OH,O)4] · 7H2O, a new mineral: the first phyllosilicate with triple tetrahedral layer

    NASA Astrophysics Data System (ADS)

    Chukanov, N. V.; Rastsvetaeva, R. K.; Aksenov, S. M.; Pekov, I. V.; Zubkova, N. V.; Britvin, S. N.; Belakovskiy, D. I.; Schüller, W.; Ternes, B.

    2012-12-01

    A new mineral, günterblassite, has been found in the basaltic quarry at Mount Rother Kopf near Gerolstein, Rheinland-Pfalz, Germany as a constituent of the late assemblage of nepheline, leucite, augite, phlogopite, åkermanite, magnetite, perovskite, a lamprophyllite-group mineral, götzenite, chabazite-K, chabazite-Ca, phillipsite-K, and calcite. Günterblassite occurs as colorless lamellar crystals up to 0.2 × 1 × 1.5 mm in size and their clusters. The mineral is brittle, with perfect cleavage parallel to (001) and less perfect cleavage parallel to (100) and (010). The Mohs hardness is 4. The calculated and measured density is 2.17 and 2.18(1) g/cm3, respectively. The IR spectrum is given. The new mineral is optically biaxial and positive as follows: ? = 1.488(2), ? = 1.490(2), ? = 1.493(2), 2 V meas = 80(5)°. The chemical composition (electron microprobe, average of seven point analyses, H2O is determined by gas chromatography, wt %) is as follows: 0.40 Na2O, 5.18 K2O, 0.58 MgO, 3.58 CaO, 4.08 BaO, 3.06 FeO, 13.98 Al2O3, 52.94 SiO2, 15.2 H2O, and the total is 98.99. The empirical formula is Na0.15K1.24Ba0.30Ca0.72Mg0.16F{0.48/2+}[Si9.91Al3.09O25.25(OH)3.75] · 7.29H2O. The crystal structure has been determined from a single crystal, R = 0.049. Günterblassite is orthorhombic, space group Pnm21; the unit-cell dimensions are a = 6.528(1), b = 6.970(1), c = 37.216(5) Å, V = 1693.3(4) Å3, Z = 2. Günterblassite is a member of a new structural type; its structure is based on three-layer block [Si13O25(OH,O)4]. The strong reflections in the X-ray powder diffraction pattern [ d Å ( I, %) are as follows: 6.532 (100), 6.263 (67), 3.244 (49), 3.062 (91), 2.996 (66), 2.955 (63), and 2.763 (60). The mineral was named in honor of Günter Blass (born in 1943), a well-known amateur mineralogist and specialist in electron microprobe and X-ray diffraction. The type specimen of günterblassite is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia, with the registration number 4107/1.

  12. Rockmagnetism and inorganic geochemistry of Grand Lake sediment, NE Russia

    NASA Astrophysics Data System (ADS)

    Minyuk, P. S.; Borkhodoev, V. Y.; Subbotnikova, T. V.

    2013-12-01

    Grand Lake, located in Magadan region (51 53'E, 60 44'N), belongs to the group of Elikchan Lakes. Maximum depth of the lake is 23.2 m. 12 cores from deep and shallow parts of the lake were taken using a Livingston corer. Sediment records from Grand Lake provide a continuous archive of climate change during marine isotopic stages (MIS) 4-1. Magnetic susceptibility (MS), saturation magnetization, saturation remanence, coercive force, remanence coercivity, temperature dependence of the induced magnetization and susceptibility of sediment and magnetic extracts were analyzed. Scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) was used to diagnose Fe-bearing minerals. MS from cores was used for correlation between the core sections. Analysis of the complex data indicate that there are four main lithologic units of sediment. Unit 1 (MIS 1), depth 0-320 cm. Upper subunit (0-150 cm) shows negative or very low MS. Sediment has high content of organic matter and SiO2 (up to 92%) because of biogenic component. The Lower subunit (depth 150-320 cm) consists of laminated organic silt. The MS of this subunit ranges from 0 to 295 (95), 10-6 SI. The sediment shows high content of Fe2O3, P2O5, MnO indicating a redox boundary. Unit 2 (MIS 2), depth 320-627 cm. Sediment is composed of laminated silt and formed during anoxic conditions. Dark thin layers are enriched with P2O5 and MnO. The unit is characterized by low MS = 57-500 (170), 10-6, SI. Vivianite and Fe-sulfides including pyrite and greigite are found in this unit. Greigite occurs in diatom valves and as fine grained aggregates and has specific thermomagnetic curves. Unit 3 (MIS 3), depth 627-965 cm. Sediment consist of homogenous silt and that accumulated during oxic conditions. Unit has highest MS in the core section: 87-1300 (480), 10-6 SI and is enriched with CaO, Na2O, K2O, SiO2. Unite 4 (MIS 4), depth-965-1015 cm includes sand, dense silt and shows high variations of MS values. According to SEM, EDX, TMA results the detrital magnetic minerals are pseudo-single-domain magnetite, titanomagnetite and titanomaghemite. Most titanomagnetites contain impurities of Al, Si and Mn. Chromium-magnetites and Ilmenite are found also. Down-core variations in magnetic and geochemical properties closely follow climatic and environmental changes established by other proxy methods including pollen and diatom data. Sediments of the warm stages (MIS 3, partly MIS 1) display a higher concentration of magnetic minerals, low values of chemical alteration index, weathering index and plagioclase index of alteration in contrast to sediments of MIS 2.

  13. Kasatkinite, Ba2Ca8B5Si8O32(OH)3 · 6H2O6, a new mineral from the Bazhenovskoe deposit, the Central Urals, Russia

    NASA Astrophysics Data System (ADS)

    Pekov, I. V.; Chukanov, N. V.; Filinchuk, Ya. E.; Zadov, A. E.; Kononkova, N. N.; Epanchintsev, S. G.; Kaden, P.; Kutzer, A.; Göttlicher, J.

    2013-12-01

    A new mineral, kasatkinite, Ba2Ca8B5Si8O32(OH)3 · 6H2O, has been found at the Bazhenovskoe chrysotile asbestos deposit, the Central Urals, Russia in the cavities in rhodingite as a member of two assemblages: (l) on prehnite, with pectolite, calcite, and clinochlore; and (2) on grossular, with diopside and pectolite. Kasatkinite occurs as spherulites or bunches up to 3 mm in size, occasionally combined into crusts. Its individuals are acicular to hair-like, typically split, with a polygonal cross section, up to 0.5 mm (rarely, to 6 mm) in length and to 20 ?m in thickness. They consist of numerous misoriented needle-shaped subindividuals up to several dozen ?m long and no more than 1 ?m thick. Kasatkinite individuals are transparent and colorless; its aggregates are snow white. The luster is vitreous or silky. No cleavage was observed; the fracture is uneven or splintery for aggregates. Individuals are flexible and elastic. The Mohs' hardness is 4-4.5. D meas = 2.95(5), D calc = 2.89 g/cm3. Kasatkinite is optically biaxial (+), ? = 1.600(5), ? = 1.603(2), ? = 1.626(2), 2 V meas = 30(20)°, 2 V calc = 40°. The IR spectrum is given. The 11B MAS NMR spectrum shows the presence of BO4 in the absence of BO3 groups. The chemical composition of kasatkinite (wt %; electron microprobe, H2O by gas chromatography) is as follows: 0.23 Na2O, 0.57 K2O, 28.94 CaO, 16.79 BaO, 11.57 B2O3, 0.28 Al2O3, 31.63 SiO2, 0.05 F, 9.05 H2O, -0.02 -O=F2; the total is 99.09. The empirical formula (calculated on the basis of O + F = 41 apfu, taking into account the TGA data) is: Na0.11K0.18Ba1.66Ca7.84B5.05Al0.08Si8.00O31.80(OH)3.06F0.04 · 6.10H2O. Kasatkinite is monoclinic, space group P21/ c, P2/ c, or Pc; the unit-cell dimensions are a = 5.745(3), b = 7.238(2), c = 20.79 (1) Å, ? = 90.82(5)°, V = 864(1) Å3, Z = 1. The strongest reflections ( d Å- I[ hkl]) in the X-ray powder diffractions pattern are: 5.89-24[012], 3.48-2.1[006], 3.36-24[114]; 3.009-100[, 121, ], 2.925-65[106, , 122], 2.633-33[211, 124], 2.116-29[, 133, 028]. Kasatkinite is named in honor of A.V. Kasatkin (b. 1970), a Russian amateur mineralogist and mineral collector who has found this mineral. Type specimen is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.

  14. Microtektite spherules from proximal K-Pg sections: alteration patterns and clues to precursor melt lithologies

    NASA Astrophysics Data System (ADS)

    Belza, J.; Goderis, S.; Smit, J.; Vanhaecke, F. F.; Baert, K.; Terryn, H.; Claeys, P. F.

    2013-05-01

    In the proximal K-Pg ejecta deposits all around the Gulf of Mexico, impact melt from the Chicxulub crater occurs predominantly in the form of glassy spherules or 'microtektites', which are considered droplets of melt that travelled ballistically from the point of impact and quenched rapidly during flight. In most localities, spherules are severely altered. Pristine, unaltered glass is very scarce and is rarely found in the center of a smectite/chlorite shell. Although the micro-tektite glass has been shown to be heterogeneous even on the ?m-scale, geochemical data have solely been reported from bulk samples. Simple binary mixing between the sedimentary carbonate and the currently described underlying crystalline basement does not fully account for the variety of tektite impact melt products, which severely complicates their interpretation. Using LA-ICP-MS, we have conducted spatially resolved analysis of trace elements in fresh, unaltered microtektite glasses and their surrounding alteration phase. This approach is unique amongst previous studies, in that it offers the opportunity to study in situ and with high spatial resolution the mixing of different target lithologies and the variation of the trace element budget during alteration. We present data from three groups of microtektite glasses at the Mimbral (NE Mexico) and Beloc (Haiti) locality: high-SiO2 green and red glasses, high-Ca yellow glass, and black glasses. All green and red glasses exhibit low oxides totals (85-90 wt%) as determined by Electron Microprobe analyses, suggesting the presence of H2O or hydrous alteration products. Raman spectroscopy clearly shows the spectrum of a hydrated glass, not an alteration phase. Their relatively high Raman index of polymerization (compared to black glass) is consistent with a normalized (water-free basis) major element composition high in SiO2 and low in network modifiers (Mg, Ca and Fe). Black and yellow glasses are not hydrated but are surrounded by a double-layered alteration rim consisting of (1) an immobile product layer depleted in SiO2, Na2O, CaO, MgO, K2O and enriched in H2O, Fe2O3, Al2O3 and TiO2. REE are depleted but still reflect the CI-normalized pattern of the precursor glass phase; (2) a palagonite/smectite phase. Most REE are below LOD and provide no clue to the composition of the precursor phase. This step-wise alteration is expressed as successive palagonite lamellae, enriched in Fe-Ti oxides that have accumulated at the alteration fronts. The type of alteration seems to be controlled by the composition of the glass. SiO2-rich green glasses (>67 wt% SiO2) seem to undergo simple hydration, whereas black SiO2 poor glasses (<65 wt% SiO2) are subjected to palagonitisation. This is consistent with the alteration mechanism postulated by Glass et al. (1997) for Cenozoic microtektites. References GLASS, B. P., MUENOW, D. W., BOHOR, B. F., & MEEKER, G. P. 1997. Fragmentation and hydration of tektites and microtektites. Meteoritics and Planetary Science, 32, 333-341.

  15. Metasediments of the Palaeoarchaean Dniester-Bug Suite of the South-Western Ukrainian Shield: composition, age, and sources

    NASA Astrophysics Data System (ADS)

    Lobach-Zhuchenko, S. B.; Bibikova, E. V.; Balagansky, V. V.

    2012-04-01

    Supracrustal rocks of the Dniester-Bug Suite are the oldest formation of the Ukrainian Shield (Esipchuk et al., 2008). They occur in the south-western shield as enclaves within enderbites. We have documented a W-E trending and subvertical enclave in the Odessa quarry (N 48°13'57", E 29°59'20") composed of mafic metavolcanics and very subordinate metasediments. SIMS zircon ages from a quartzite vary from 3.8 to 3.1 Ga, the majority of concordant values being 3.7-3.5 Ga (Bibikova et al., 2012). Younger metamorphic zircons are also present. In the south this enclave is bounded by a 3.1 Ga old enderbite which contains a xenolith of a metavolcanite identical to those alternating with metasediments (Lobach-Zhuchenko et al., 2012). So, the formation of supracrustals is constrained by the interval 3.4-3.2.Ga. Sedimentary lithologies have been recognised as pure quartzites and garnet, garnet-magnetite, and magnetite quartzites. Metasediments form lenses of different length, and their thickness varies from a few centimetres to 2.5 m. All supracrustal rocks experienced multiple deformation coeval with two high-grade (up to granulite facies) metamorphic events accompanied by migmatization. The second deformation resulted in W-E trending lens-like and banded structures and penetrative steep to vertical mineral and aggregate lineation, which suggests widely developed ductile shearing. Geochemically, the sediments are subdivided into quartzites, alumina-iron quartzites and iron quartzites (Algoma-type IF). High abundances in quartzites and alumina-iron quartzites of Al2O3 (2-8 and 3-20 wt %), CaO (0.9-3.64 and 1.4-3.6 wt %), MgO (0.7-4.4 and 3.5-6.7 wt %), TiO2 (0.07-0.23 and 0.56-1.28 wt %), respectively, and the ratio Na2O/Al2O3 of 0.05-0.20 point to their terrigenic origin. According to Herron's classification of terrigenic rocks (Herron, 1988) predominant sediments are Fe-sandstones; some of rocks correspond to quartz arenites and Fe-Al shales; in addition, Fe quartzites (IF) are present. The high Sc content also suggests the clastic origin of these rocks. The chemical index of alteration (Nesbitt, Young, 1982; 42-48 in quartzites and 40-89 in IF) indicates a weak weathering grade. The Zr-Hf ratio of 30-40 suggests an input of continental component. The K2O/Al2O3 ratio of 0.02-0.07 indicates an important role of plagioclase in an weathering area. Most samples have the concentration of LREE 10-50 times higher, and of HREE 1-9 times higher than in chondrites. The enrichment of LREE is thought to have been due to metamorphism. The IF displays a negative Eu anomaly, which also could have resulted from metamorphism (Fryer, 1983). In comparison with the average Algoma-type IF (Gross and McLeod, 1980) IF from the Odessa quarry have lower abundances of Co, Ni, Cr, Zn, and higher abundances of Cu and V; abundances of all transitional metals in the alumina-iron quartzites are higher. The Fe/Mn ratios are of 28-88 in quartzites and 420 in IF, and according to Rosen et al. (1994) these values suggest that sedimentation occurred in shallow basins. Thus, all geochemical features indicate the terrigenic origin of quartzites, Al-Fe quartzites and IF in contrast to most chemical sediments of Archaean Algoma-type IF.

  16. Burovaite-Ca, (Na,K)4Ca2(Ti,Nb)8[Si4O12]4(OH,O)8·12H2O, a new labuntsovite-group mineral species and its place in low-temperature mineral formation in pegmatites of the Khibiny pluton, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Azarova, Yu. V.; Shlyukova, Z. V.; Zolotarev, A. A.; Organova, N. I.

    2009-12-01

    This paper presents data on burovaite-Ca, the first Ti-dominant member of the labuntsovite group with a calcium D-octahedron. The idealized formula of burovaite-Ca is (K,Na)4Ca2(Ti,Nb)8[Si4O12]4(OH,O)8 · 12H2O. The mineral has been found in the hydrothermal zone of aegirine-microcline pegmatite located in khibinite at Mt. Khibinpakhkchorr, the Khibiny pluton, Kola Peninsula, Russia. Radiaxial intergrowths of burovaite-Ca and labuntsovite-Mn associated with lemmleynite-Ba, analcime, and apophyllite have been identified in caverns within microcline. The mean composition of the mineral is as follows, wt %: 3.72 Na2O, 2.76 K2O, 4.22 CaO, 0.47 SrO, 0.23 BaO, 0.01 MnO, 0.30 Fe2O3, 0.14 Al2O3, 42.02 SiO2, 17.30 TiO2, 15.21 Nb2O5, 12.60 H2O (measured); the total is 98.98. Its empirical formula has been calculated on the basis of [(Si,Al)16O48]: {(Na3.10K1.07Ca0.37Sr0.04Ba0.04)4.62}(Ca1.28Zn0.01)1.29(Ti4.97Nb2.56Fe0.08Ta0.02)7.63(Si15.93Al0.07)16O48(OH6.70O0.93)7.63 · 12H2O. The strongest lines in the X-ray powder diffraction pattern of burovaite-Ca ( I-d Å] are as follows: 70-7.08, 40-6.39, 40-4.97, 30-3.92, 40-3.57, 100-3.25, 70-3.11, 50-2.61, 70-2.49, 40-2.15, 50-2.05, 70-1.712, 70-1.577, and 70-1.444. The structure of burovaite-Ca was solved by A.A. Zolotarev, Jr. The mineral is monoclinic, space group C2/ m. The unit-cell dimensions are a = 14.529(3), b = 14.203(3), c = 7.899(1), ? = 117.37(1)°, V = 1447.57 Å3. Burovaite-Ca is an isostructural Ti-dominant analogue of karupmøllerite-Ca and gjerdingenite-Ca. Two stages of mineral formation—pegmatite proper and hydrothermal—have been recognized in the host pegmatite. The hydrothermal stage included K-Ba-Na, Na-K-Ca, and Na-Sr substages. Burovaite-Ca is related to the intermediate Na-K-Ca substage. At the first substage, labuntsovite-Mn and lemmleynite-Ba were formed, and tsepinite-Na, paratsepinite-Nd, and tsepinite-Sr were formed at the final substage. Thus, the sequence of crystallization of labuntsovite-group minerals is characterized by the replacement of the potassium regime by the sodium regime of alkaline solutions in the evolved host pegmatite.

  17. Subduction Cycling of C-O-H Volatiles Constrained by Near-Solidus Phase Relations of Water-undersaturated, Carbonated Pelite at 3 GPa

    NASA Astrophysics Data System (ADS)

    Tsuno, K.; Dasgupta, R.

    2010-12-01

    While the petrology of water release from subducting slab to magmatic arcs is reasonably well-understood, similar cycle of carbon is a poorly understood process. Subducting sediments globally contribute to the geochemical characteristics of arc magmas1, but sedimentary carbonates are predicted to survive shallow dehydration2. Previous experiments on Fe-calcareous clay of Lesser Antilles3 and dry, carbonated pelite composition relevant for Central American trench4 suggested that melting also may not be efficient in releasing CO2 to mantle wedge. To add to the discussion, here we present results from new high pressure experiments on water-undersaturated, CO2-saturated pelitic compositions. Piston cylinder experiments using Au capsules were carried out at 3.0 GPa and 800-1150 °C, using two starting compositions, both containing 5 wt.% CO2 and 1 wt.% H2O, The SiO2 contents of the two bulk compositions were varied (HPLC2: ~60 wt.% and HPLC3: ~51 wt.%) to capture variable loss of silica during shallow dehydration. The subsolidus phase assemblages for both the compositions are identical and at 800 °C comprise cpx + garnet + coesite + Fe-Mg-calcite + phengite + rutile. The solidi are located between 800 and 850 °C and phengite disappears and K-spar appears at 900 °C. Calcitic carbonate disappears at 950-1000 °C for both the compositions. Melts in all the experiments at ?900 °C are fluid-saturated and are rhyolitic in composition. Silicate melt compositions show a decrease in SiO2 and an increase of TiO2, FeO, and CaO with increasing temperature. Al2O3, MgO, Na2O, and K2O in the melt varied little with temperature. The temperatures of solidus, phengite-out, and carbonate breakdown are respectively ~50 °C, ~50 °C, and ~75 °C lower compared to those determined for a calcareous clay3 at similar pressures. Our study suggests that calcitic carbonate and phengite are likely cycled into the deep Earth via relatively cool subduction (<800 °C slab-surface temperature at 3 GPa), whereas dehydration melting of phengite might be encountered for warm subduction zones (800-950 °C at 3 GPa5). Melting of downgoing sediments in warm subduction zones, although is efficient in releasing water to mantle wedge, unlikely strips-off all the carbon as calcitic carbonate remains stable in the residue 100-200 °C above the solidus. Main pulse of slab-CO2 at sub-arc depths may come from sediment diapirs that, owing to lower densities with respect to peridotite, upwell and undergo super-adiabatic melting in the mantle wedge. 1Plank, T. and Langmuir, C. 1993, Nature 362, 739-743. 2Kerrick, D. M. and Connolly, J. A. D. 2001, Nature 411, 293-296. 3Thomsen, T.B. and Schmidt, M.W., EPSL 267, 17-31. 4Tsuno, K. and Dasgupta, D. 2010, Contrib Mineral Petrol doi: 10.1007/s00410-010-0560-9 5Syracuse, E. M., van Keken, P. E. and Abers, G. A. 2010, PEPI doi:10.1016/j.pepi.2010.02.004

  18. Fluor-ferro-leakeite, NaNa2(FC2+2Fe3+2Li)Si8O22F2, a new alkali amphibole from the Canada Pinabete pluton, Questa, New Mexico, U.S.A.

    USGS Publications Warehouse

    Hawthorne, F.C.; Oberti, R.; Ungaretti, L.; Ottolini, L.; Grice, Joel D.; Czamanske, G.K.

    1996-01-01

    Fluor-ferro-leakeite is a new amphibole species from the Canada Pinabete pluton, Questa, New Mexico, U.S.A.; it occurs in association with quartz, alkali feldspar, acmite, ilmenite, and zircon. It forms as anhedral bluish black crystals elongated along c and up to 1 mm long. It is brittle, H = 6, Dmeas = 3.37 g/cm3, Dcalc = 3.34 g/cm3. In plane-polarized light, it is strongly pleochroic, X = very dark indigo blue, Y = gray blue, Z = yellow green; X ??? c = 10?? (in ??obtuse), Y = b, Z ??? a = 4?? (in ?? obtuse), with absorption X > Y > Z. Fluor-ferro-leakeite is biaxial positive, ?? = 1.675(2), ??= 1.683(2), ?? = 1.694(1); 2V = 87(2)??; dispersion is not visible because of the strong absorption. Fluor-ferro-leakeite is monoclinic, space group C2/m, a = 9.792(1), b = 17.938(1), c = 5.3133(4) A??, ??= 103.87(7)??, V = 906.0(1) A??3, Z = 2. The ten strongest X-ray diffraction lines in the powder pattern are [d(I,hkl)]: 2.710(100,151), 2.536(92,202), 3.404(57,131), 4.481(54,040), 8.426(45,110), 2.985(38,241), 2.585(38,061), 3.122(29,310), 2.165(26,261), and 1.586(25,403). Analysis by a combination of electron microprobe, ion microprobe, and crystal-structure refinement (Hawthorne et al. 1993) gives SiO2 51.12, Al2O3 1.13, TiO2 0.68, Fe2O3 16.73, FeO 8.87, MgO 2.02, MnO 4.51, ZnO 0.57, CaO 0.15, Na2O 9.22, K2O 1.19, Li2O 0.99, F 2.87, H2Ocalc 0.60, sum 99.44 wt%. The formula unit, calculated on the basis of 23 O atoms, is (K0.23Na0.76)(Na1.97Ca0.03)(Mg 0.46Fe2+1.4Mn2+0.59Zn0.07Fe3+1.93-Ti 0.08Al0.02Li0.61])(Si7.81Al 0.19)O22(F1.39OH0.61). A previous crystal-structure refinement (Hawthorne et al. 1993) shows Li to be completely ordered at the M3 site. Fluor-ferro-leakeite, ideally NaNa2(Fe2+2Fe3+2Li)Si8O22F2, is related to leakeite, NaNa2(Mg2Fe3+3Li)Si 8O22(OH)2, by the substitutions Fe2+ ??? Mg and F ??? OH.

  19. Geochemistry, provenance, and tectonic setting of Neoproterozoic metavolcanic and metasedimentary units, Werri area, Northern Ethiopia

    NASA Astrophysics Data System (ADS)

    Sifeta, K.; Roser, B. P.; Kimura, J.-I.

    2005-02-01

    Major, trace and rare earth element (REE) compositions of upper Proterozoic metavolcanic and metasedimentary rocks from the Tsaliet and Tembien Groups in the Werri district of northern Ethiopia were determined to examine their tectonic setting of eruption, provenance and source area weathering conditions. Tsaliet Group metavolcanic rocks in the Werri area have sub-alkaline chemistry characterized by low to intermediate SiO 2 contents, high Al 2O 3, low MgO and very low Cr and Ni. High field strength element (HFSE) abundances are highly variable. ?REE abundances vary from 66.7 to 161.3 ppm, and chondrite-normalized REE patterns are moderately fractionated, with La N/Yb N values of between 3.1 and 9.0. Europium anomalies are variable (Eu/Eu* 0.80-1.21) but are generally positive (average Eu/Eu* 1.06). On tectonic discrimination diagrams, most samples have either volcanic-arc chemistry or fall in the overlap field with mid-oceanic ridge basalt (MORB). However, primitive mantle-normalized trace element abundances are comparable with sub-alkaline basalts from developed island arcs. 147Sm/ 144Nd ratios range from 0.1167 to 0.1269 ( n = 3), yielding initial ?Nd (800 Ma) of +3.8 to +4.9 and mean TDM model age of 0.96 Ga, indicative of derivation from juvenile Neoproterozoic mantle. Metasediments from three locations (Werri1, Werri2 and Tsedia) in the Werri and Tsedia Slates have similar Al 2O 3, TiO 2 and HFSE contents but variable and low Na 2O, CaO and K 2O. Cr and Ni are slightly enriched in the Werri2 and Tsedia suites. SiO 2 is very variable, with average values of 70.75, 72.2 and 66.4 wt.% in the Werri1, Werri2 and Tsedia suites, respectively. ?REE abundances in the metasediments (14.74-108.1) are lower than in the metavolcanics, and are slightly less fractionated, with La N/Yb N ratios of 0.8-5.9. Europium anomalies vary (Eu/Eu* 0.80-1.21) but are insignificant on average (Eu/Eu* 0.96). High values for the Chemical Index of Alteration (generally 70-90), and Plagioclase Index of Alteration (>75) in the Werri metasediments indicate moderate to severe chemical weathering in their source. Average major and trace element compositions of the metasediments and their REE patterns are comparable with the metavolcanics. 147Sm/ 144Nd ratios of the metasediments range from 0.1056 to 0.1398 ( n = 4), with initial ?Nd (800 Ma) of +3.4 to +5.0 and mean TDM model age of 0.97 Ga, indicating derivation from juvenile Neoproterozoic crust similar to the underlying metavolcanics, with minimal (4-10%) contribution from older crust. The most sensitive tectonic setting discriminators indicate the Werri metasediments represent developed oceanic island arc sediments. The chemical similarity of the Werri metavolcanics to the nearby Adwa metavolcanics, Nakfa terrane in Eritrea, and volcanic units in central Saudi Arabia imply that juvenile Neoproterozoic Arabian Nubian Shield crust extended south at least as far as the Werri area of northern Ethiopia. The comparable geochemistry of the metasediments and their underlying lithologies attests to their derivation from this juvenile crustal material.

  20. P2O5-doping in waste glasses: evolution of viscosity and crystallization processes

    NASA Astrophysics Data System (ADS)

    Tarrago, Mariona; Espuñes, Alex; Garcia-Valles, Maite; Martinez, Salvador

    2015-04-01

    Current concern for environmental preservation is the main motive for the study of new, more sustainable materials. Increasing amounts of sewage sludge are produced in wastewater treatment plants over the world every day. This fact represents a major problem for the municipalities and industries due to the volume of waste and also to the contaminant elements it may bear, which require expensive conditions for disposal in landfills. Vitrification is an established technique in the inertization of different types of toxic wastes (such as nuclear wastes and contaminated soils) that has been used successfully for sewage sludge. Glasses of basaltic composition (43.48SiO2-14.00Al2O3-12.86Fe2O3-10.00CaO-9.94MgO-3.27Na2O-1.96K2O-0.17MnO-0.55P2O5-2.48TiO2) are used as a laboratory analogous of wastes such as sewage sludge and galvanic sludge to study the properties of the inertization matrix. This basaltic matrix is doped by adding 1%, 2%, 3%, 4% and 20% of P5O5 in order to cover the compositional range of phosphate in sewage sludge encountered in the literature. In this study, the focus has been placed in the effect of the concentration of phosphate (P2O5) in glass stability, thermal properties and evolution of viscosity with temperature. The dependence of viscosity on temperature and the thermal behaviour of these glasses are critical parameters in the design of their production process. Regarding the compositional limits of the mixture, it has been observed that melt reactivity is much increased when P2O5 content is over 4%, hindering the glass conformation process. Moreover, stanfieldite (calcium and magnesium phosphate) crystallized during glass making when phosphate concentration approached 20%, hence establishing the upper limit for glass stability. Viscosity is also dramatically increased in this range, hence requiring production amends. Differential thermal analysis has provided nucleation and crystallization temperatures of the glasses around 915°C and 1050°C respectively at phosphate contents up to 4%. Subsequent analysis by X-Ray Diffraction has proved that newly formed phases are iron oxides, Ca - Mg silicates and feldspars. Glass transition temperature (Tg; approximately 635°C) obtained by dilatometry remains almost constant until very high phosphate contents; even then, the increase is not large (650°C at 20% P2O5). Hot-Stage microscopy (HSM) has shown the evolution of viscosity with temperature through the analysis of the morphological evolution of cylindrical probes of glass according to German standard DIN 51730. The annealing range (viscosity between 1013.5 and 1012 is reached at temperatures between 600 and 700°C. The temperatures of the lower limit of the working range (viscosity under 103 Pa-s) are between 1325 and 1375°C; decreasing slightly with the addition of P2O5.

  1. Dyke belt in North Western margin of Siberian platform

    NASA Astrophysics Data System (ADS)

    Ryabov, Victor

    2015-04-01

    The Early Triassic dyke swarm belt is strengthening at about 500 km (50-60 km width) along the northern margin of Siberian platform. Its locations is limited from the north by rift structure of the Yenisei-Khatanga trough, and from the south by Kystyktah-Ayan-Ambardah uprise. From west to east dyke belt is crossing Norilsk, Kamensky and Maimecha-Kotuiskaya province. In this direction the composition of dykes changing from basic rthrough alkali-basic to alkali-ultramafic varieties. The sickness of dykes varies from 0,5-10m up to 90 m and length - from 5-15 m to 140 km. The orientation of the bulk of dykes coincides with the direction of the major structural and tectonic lineaments of the region. Dykes are often refer to the fault planes. The composition of dykes may vary along the stretches. The density of hundreds of basaltic dykes and small intrusions in the dyke swarms is not permanent and sometimes essentially uneven. They form a compact dyke swarms of dykes, stocks and sub layering bodies veins. In dyke package on Huor-Uyallah river here are 20 subparallel dykes of different chemical composition at a distance of 2 km Lack of the evidence of the dykes crossing allows to assume their formation during the same magmatic cycle. Dykes cross cut through the entire incision of basaltic plateau. They did not created the flow effusions and refer to the final stage trap magmatism. Ar/Ar age of the youngest dykes in the province Kamenska 238-247 Ma. the age of lamproite dyke in Norilsk province is 235 Ma. Dykes are represented by dolerites trachydolerites, syenites, minettes, lamprophyres (camptonite, spessartite, vosgesite), avgitites, melanephelinite, alnoites, limburgites alkaline picrites, meimechites. Their content vary widely: SiO2 - 35,7-62,6; TiO2- 0,4-7,5; Al2O3- 4,4-17,5; Fe2O3- 4,6-20,6; MnO- 0,08-0,44; MgO- 0,8-31,5; CaO- 0,7-15,4; Na2O- 0,01-6,5; K2O 0,8-5,3 wt.%; P2O5 0,1-1,2 wt.%. The h Bolsheavamskaya volcanic basin in Kamensky province is most abundant in ighly alkali-basicdykes. There are undifferentiated and layered dykes, glassy and crystalline, single and multi-phase, with symmetric and asymmetric internal structure, with uniform or contrasting composition of the individual phases. Multiphase dykes along the. Namakan river have symmetrical "dyke dyke" structure. Glassy dykes are usually composed of olivine clinopyroxenite or picritic olivine porphyres. The number of dykes phases in the same locality may reaches 5. The internal structure of dykes are symmetric. The dyke in dyke consists of the quench zone in inner contact zone with silicate glass and carbonate globules and enriched by rounded K-feldspar, potassium feldspar with kaersutite +- mica glomeroporhyric intergrowth. In crystalline dykes contact zones are composed of variolitic clinopyroxenites and central by picritic porphyries. Contact zone composed of clinopyroxenites crystallized from a supercooled melt. Having elevated CaTi- and CaAl-tschermak components. This Dyke belt was formed by scattered spreading. Multiphase dykes were formed during multiple tectonic fracturing. Wide chemical variations c are caused by fluid-magmatic melt interaction in magma feeding channels. Multistage splitting of magmatic melts to different in composition liquids took place with the participation of CO2, H2, F, Cl, CH4.

  2. Analyses of Clay Mineralogy of some Southeastern Nigeria Soils using X-Ray Diffraction and Fluorescence Techniques

    NASA Astrophysics Data System (ADS)

    Igwe, C.; Stahr, K.

    2009-04-01

    Detailed knowledge of soil mineralogy helps in understanding the soil forming processes, the chemical constituent and the general characteristics of the soil. We used x-ray diffraction (XRD) and fluorescence techniques (XRF) to analyse the clay mineralogy and soil chemical properties of varieties of soils within south-eastern Nigeria. The XRD involved both powder and oriented clay analyses. The aim was to determine the clay minerals in both whole sample (fine-earth fraction) and the oriented clays. Soils analysed were from floodplain of alluvial deposits to upland soils derived from shale and sandstone geological formation. The XRD patterns of the clay fraction from selected soils indicate that they are well-defined diffractions at 0.72 nm indicating kaolinite as the dominant clay mineral. Kaolinites are mainly the alumina-silicate clays with 1:1 octahedral and tetrahedral relationship. The 2:1 clay minerals present were illite at 1.0 nm for soils formed on the shale formations, interlayer vermiculite (IV) occurred at 1.4 nm again for soils on shales while smectite was observed especially in floodplain soils at 1.8 nm in those soils. The presence of smectite where it occurred, showed that diffraction peaks found between 1.0 and 1.4 nm in Mg-saturated samples shifted to 1.8 nm after the samples were solvated with glycerol, indicating the presence of smectite in various quantities in the soils. The presence of the 1:1 and 2:1 minerals can be used as a basis for grouping of the soils into expanding and non expanding soils. This grouping is very significant in all activities aimed at managing the soils for sustainable productivity. The energy-dispersive x-ray (EDX) analyses of the clays confirm the dominance of Si and Al in the soils. In some of the soils EDX showed the presence of K and Fe as being one of the prominent elemental components of the clay minerals. The geochemical properties of the soils as shown by XRF were dominated by the SiO2, Al2O3 and the Fe2O3 while such elements as MgO, TiO2 and ZrO2 occur in moderate to low quantities. Gibbsite and hematite were the major oxide minerals identified by XRD in the upland soils while lepidocrocites were identified in the floodplain soil types. The other basic elements such as Na2O, K2O and CaO are very low in the soils with very insignificant role to play in their genesis. XRD and XRF are therefore very essential tool in soil clay mineralogy and clan be employed in the study of soil genesis and classification, soil physics and soil chemistry/fertility.

  3. Stability of Basalt plus Anhydrite plus Calcite at HP-HT: Implications for Venus, the Earth and Mars

    NASA Technical Reports Server (NTRS)

    Martin, A. M.; Righter, K.; Treiman, A. H.

    2010-01-01

    "Canali" observed at Venus surface by Magellan are evidence for very long melt flows, but their composition and origin remain uncertain. The hypothesis of water-rich flow is not reasonable regarding the temperature at Venus surface. The length of these channels could not be explained by a silicate melt composition but more likely, by a carbonate-sulfate melt which has a much lower viscosity (Kargel et al 1994). One hypothesis is that calcite CaCO3 and anhydrite CaSO4 which are alteration products of basalts melted during meteorite impacts. A famous example recorded on the Earth (Chicxulub) produced melt and gas rich in carbon and sulfur. Calcite and sulfate evaporites are also present on Mars surface, associated with basalts. An impact on these materials might release C- and S-rich melt or fluid. Another type of planetary phenomenon (affecting only the Earth) might provoke a high pressure destabilization of basalt+anhydrite+calcite. Very high contents of C and S are measured in some Earth s magmas, either dissolved or in the form of crystals (Luhr 2008). As shown by the high H content and high fO2 of primary igneous anhydrite-bearing lavas, the high S content in their source may be explained by subduction of an anhydrite-bearing oceanic crust, either directly (by melting followed by eruption) or indirectly (by release of S-rich melt or fluid that metasomatize the mantle) . Calcite is a major product of oceanic sedimentation and alteration of the crust. Therefore, sulfate- and calcite-rich material may be subducted to high pressures and high temperatures (HP-HT) and release S- and C-rich melts or fluids which could influence the composition of subduction zone lavas or gases. Both phenomena - meteorite impact and subduction - imply HP-HT conditions - although the P-T-time paths are different. Some HP experimental/theoretical studies have been performed on basalt/eclogite, calcite and anhydrite separately or on a combination of two. In this study we performed piston-cylinder experiments at 1 GPa between 950 and 1700 C using a mixture of 70wt% tholeiitic basalt + 15wt% anhydrite + 15wt% calcite. Up to 1440 C, an ultracalcic (CaO>13.5 wt%; CaO/Al2O3>1 wt%) picrobasaltic (SiO240-45 wt%; Na2O+K2O<2 wt%) melt containing up to 5 wt% SO3 and up to 5.3 wt% CO2+H2O (calculated by difference) is present in equilibrium with clinopyroxene, anhydrite, spinel-chromite, a CAS-phase and a gas composed mainly of CO and an aliphatic thiol (CH2)4SH. Hydrogen was incorporated either by contact between the starting material and air or by diffusion through the capsule during the experiments. The S content in the gas increases with temperature and run duration, implying that gases with various C/S ratios might be released during an impact or at subduction zones, depending on the P-T-t path and on the H content. Above approx.1440 C, a Ca-rich carbonate-sulfate melt forms (in equilibrium with the picrobasaltic melt) which contains a few percents of Na and K. Such melt is not expected to form at Earth s subduction temperatures. If it forms by meteorite impact, it might crystallize too fast to explain long flows like Venus canali. A different basalt/anhydrite/calcite ratio might, however, decrease its formation temperature.

  4. Magma Recharge and Mixing Processes That Triggered the Eruption of Trachytes and Phonolites at Suswa Volcano, Kenya Rift, East Africa

    NASA Astrophysics Data System (ADS)

    Espejel-Garcia, V.; Anthony, E. Y.; Ren, M.; MacDonald, R.; White, J. C.

    2007-12-01

    Suswa Volcano, one of a series of Holocene central vent volcanoes located in the central part of the Kenya Rift, is divided into four major stages: 1) pre-caldera; 2) syn-caldera; 3) post-caldera I; and 4) post-caldera II. In addition to central vent volcanoes are basalt and basaltic-trachyandesite (BTA) flows (e.g. Tandamara and Elmenteita) that occur in low-lying areas adjacent to the central volcanoes. Both pre- and syn-caldera rocks include trachyte to phonolite. Syn-caldera rocks also include BTA similar to Tandamara. Matrix glass in pre-caldera samples is similar to whole-rock. However, for syn-caldera samples, light and dark mixed glasses are observed petrographically and compositions range from trachyandesite to trachyte. Pre-caldera samples have a phenocryst assemblage of anorthoclase (An0-5Ab50-60Or30-45), clinopyroxene (En27Fs28Wo45) and Fe-Ti oxide. Syn-caldera trachyte-phonolite contain this same assemblage but also plagioclase (An52Ab45Or3), with a composition identical to BTA samples. Clearly, the syn-caldera event represents magma mixing between BTA and trachyte. With the developing East Africa rifting, introduction of mafic magmas into the Suswa trachytic chamber was possible, similar to the rupture events in Ethiopia in 2005 (Wright et al., 2006). Post-caldera rocks have phenocrysts of alkali feldspar, olivine (Fa70), clinopyroxene and Fe-Ti oxides. Post-caldera II alkali feldspars are zoned and contain two different core compositions, one with low anorthite content similar to pre- and syn-caldera samples (An3Ab64Or33) and the other with higher anorthite content (An17Ab69Or14). They exhibit oscillatory zoning, with compositional variation between Ca2O and K2O and have thin rims with composition similar to the matrix feldspars. The thin rims may represent magma recharge that triggered eruption of the phonolite. Matrix glass in post-caldera rocks includes both trachyandesite and phonolite, indicating that hybridization of the contrasting magmas is still ongoing. Processes in addition to mixing contribute to this dynamic volcanic setting. Post-caldera rocks have compositions of essentially all elements that are intermediate between BTA and trachyte, as appropriate to mixing. However, samples show variable Na20 content at constant K20, Fe0, MgO, and CaO. A possible explanation for this variable Na2O content is assimilation of sodalite-bearing syenite roof and sidewall rocks into the evolving magma chamber. References: Wright, T.J., et al., 2006, Magma-maintained rift segmentation at continental rupture in the 2005 Afar dyking episode. Nature, 442: 291-294.

  5. Zvyaginite, NaZnNb2Ti[Si2O7]2O(OH,F)3(H2O)4 + x ( x < 1), a new mineral of the epistolite group from the Lovozero Alkaline Pluton, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Pekov, I. V.; Lykova, I. S.; Chukanov, N. V.; Yapaskurt, V. O.; Belakovskiy, D. I.; Zolotarev, A. A.; Zubkova, N. V.

    2014-12-01

    A new mineral, zvyaginite, a member of the epistolite group, has been found at Mt. Malyi Punkaruaiv, Lovozero Alkaline Complex, Kola Peninsula, Russia. It occurs in a hydrothermally altered peralkaline pegmatite and is associated with ussingite, microcline, aegirine, sphalerite, vigrishinite, and sauconite. Zvyaginite forms rectangular or irregular-shaped lamellae up to 0.1 × 1 × 2 cm in size when flattened [001]. The mineral is translucent to transparent and colorless, pearly-white, yellowish brownish, pale pink, or violet pink. The luster is nacreous on crystal faces and greasy on broken surfaces. Its Mohs' hardness is 2.5-3. Zvyaginite is brittle. The cleavage parallel to {001} is perfect. D meas = 2.88(3), D calc = 2.94 g/cm3. The mineral is optically biaxial (-), ? = 1.626(5), ? = 1.714(3), ? = 1.740(5), 2 V meas = 45(15)°, 2 V calc = 55°. The IR spectrum is given. Chemical composition is as follows (wt %; average of five point analyses; H2O was determined using the modified Penfield method): 4.74 Na2O, 0.22 K2O, 0.77 CaO, 1.36 MnO, 0.24 FeO, 9.61 ZnO, 0.19 Al2O3, 29.42 SiO2, 12.33 TiO2, 27.22 Nb2O5, 1.94 F, 12.65 H2O, -0.82 -O = F2, for a total of 99.87. The empirical formula calculated on the basis of Si + Al = 4 is: Na1.24K0.04Ca0.11Mn0.16Fe0.03Zn0.96Nb1.66Ti1.25(Si3.97Al0.03)?4O15.07(OH)2.10F0.83(H2O)4.64. The simplified formula is: NaZnNb2Ti[Si2O7]2O(OH,F)3(H2O)4 + x ( x < 1), Zvyaginite is triclinic, , a = 8.975(3), b = 8.979(3), c = 12.135(4) Å, ? = 74.328(9)°, ? = 80.651(8)°, ? = 73.959(8)°, V = 900.8(6) Å3, Z = 2. The strongest reflections in the X-ray powder pattern ( d, Å- I[ hkl]) are: 11.72-100[001], 5.83-40[002], 5.28-53[-1-11, 112], 4.289-86[200, 021], 3.896-36[-1-12, -201, 003, 022, 113], 2.916-57[310, 132, 004], 2.862-72[130, 312]. The model of the crystal structure was obtained on a single crystal, R = 0.159. Zvyaginite and epistolite are similar in the structure of the NbTiSiO motif, but differ from each other in composition of O layer in HOH block. Zvyaginite is named in honor of Boris B. Zvyagin (1921-2002), Russian crystallographer, crystal chemist and physicist. The type specimen is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.

  6. Geochronology and geochemistry of Cretaceous Nanshanping alkaline rocks from the Zijinshan district in Fujian Province, South China: Implications for crust-mantle interaction and lithospheric extension

    NASA Astrophysics Data System (ADS)

    Li, Bin; Jiang, Shao-Yong

    2014-10-01

    In situ zircon U-Pb ages and Hf isotopic data, major and trace elements, and Sr-Nd-Pb isotopic compositions are reported for Nanshanping alkaline rocks from the Zijingshan district in southwestern Fujian Province (the Interior or Western Cathaysia Block) of South China. The Nanshanping alkaline rocks, which consist of porphyritic quartz monzonite, porphyritic syenite, and syenite, revealed a Late Cretaceous age of 100-93 Ma. All of the rocks show high SiO2, K2O + Na2O, and LREE but low CaO, Fe2O3T, MgO, and HFSE (Nb, Ta, P, and Ti) concentrations. These rocks also exhibit uniform initial 87Sr/86Sr ratios of 0.7078 to 0.7087 and ?Nd(t) values of -4.1 to -7.2, thus falling within the compositional field of Cretaceous basalts and mafic dikes occurring in the Cathaysia Block. Additionally, these rocks display initial Pb isotopic compositions with a 206Pb/204Pbi ratio of 18.25 to 18.45, a 207Pb/204Pbi ratio of 15.63 to 15.67, and a 208Pb/204Pbi ratio of 38.45 to 38.88. Combined with the zircon Hf isotopic compositions (?Hf(t) = -11.7 to -3.2), which are different from those of the basement rocks, we suggest that Nanshanping alkaline rocks were primarily derived from a subduction-related enriched mantle source. High Rb/Sr (0.29-0.65) and Zr/Hf (37.5-49.2) but relatively low Ba/Rb (4.4-8.1) ratios suggest that the parental magmas of these rocks were most likely formed via partial melting of a phlogopite-bearing mantle source with carbonate metasomatism. The relatively high SiO2 (62.35-70.79 wt.%) and low Nb/Ta (10.0-15.3) ratios, positive correlation between SiO2 and (87Sr/86Sr)I, and negative correlation between SiO2 and ?Nd(t) of these rocks suggest that the crustal materials were also involved in formation of the Nanshanping alkaline rocks. Combined with geochemical and isotopic features, we infer magmatic processes similar to AFC (assimilation and fractional crystallization) involving early fractionation of clinopyroxene and olivine and subsequent fractionation of biotite-dominated assemblages coupled with a lesser amount of crustal contamination, thereby forming the Nanshanping alkaline rocks. The Nanshanping alkaline rocks appear to be associated with an extensional environment in the Cathaysia Block. This extensional regime could have resulted in the slab break-off and rollback of the subducting paleo-Pacific plate and the upwelling of the asthenospheric mantle, which induced partial melting of the enriched lithospheric mantle in the Cretaceous.

  7. Middendorfite, K3Na2Mn5Si12(O,OH)36 · 2H2O, a new mineral species from the Khibiny pluton, Kola Peninsula

    NASA Astrophysics Data System (ADS)

    Pekov, I. V.; Chukanov, N. V.; Dubinchuk, V. T.; Zadov, A. E.

    2007-12-01

    Middendorfite, a new mineral species, has been found in a hydrothermal assemblage in Hilairite hyperperalkaline pegmatite at the Kirovsky Mine, Mount Kukisvumchorr apatite deposit, Khibiny alkaline pluton, Kola Peninsula, Russia. Microcline, sodalite, cancrisilite, aegirine, calcite, natrolite, fluorite, narsarsukite, labuntsovite-Mn, mangan-neptunite, and donnayite are associated minerals. Middendorfite occurs as rhombshaped lamellar and tabular crystals up to 0.1 × 0.2 × 0.4 mm in size, which are combined in worm-and fanlike segregations up to 1 mm in size. The color is dark to bright orange, with a yellowish streak and vitreous luster. The mineral is transparent. The cleavage (001) is perfect, micalike; the fracture is scaly; flakes are flexible but not elastic. The Mohs hardness is 3 to 3.5. Density is 2.60 g/cm3 (meas.) and 2.65 g/cm3 (calc.). Middendorfite is biaxial (-), ? = 1.534, ? = 1.562, and ? = 1.563; 2 V (meas.) = 10°. The mineral is pleochroic strongly from yellowish to colorless on X through brown on Y and to deep brown on Z. Optical orientation: X = c. The chemical composition (electron microprobe, H2O determined with Penfield method) is as follows (wt %): 4.55 Na2O, 10.16 K2O, 0.11 CaO, 0.18 MgO, 24.88 MnO, 0.68 FeO, 0.15 ZnO, 0.20 Al2O3, 50.87 SiO2, 0.17 TiO2, 0.23 F, 7.73 H2O; -O=F2-0.10, total is 99.81. The empirical formula calculated on the basis of (Si,Al)12(O,OH,F)36 is K3.04(Na2.07Ca0.03)?2.10(Mn4.95Fe0.13Mg0.06Ti0.03Zn0.03)?5.20(Si11.94Al0.06)?12O27.57(OH)8.26F0.17 · 1.92H2O. The simplified formula is K3Na2Mn5Si12(O,OH)36 · 2H2O. Middenforite is monoclinic, space group: P21/ m or P21. The unit cell dimensions are a = 12.55, b = 5.721, c = 26.86 Å; ? = 114.04°, V = 1761 Å3, Z = 2. The strongest lines in the X-ray powder pattern [ d, Å, ( I)( hkl)] are: 12.28(100)(002), 4.31(81)(11overline 4 ), 3.555(62)(301, 212), 3.063(52)(008, 31overline 6 ), 2.840(90)(312, 021, 30overline 9 ), 2.634(88)(21overline 9 , 1.0.overline 1 0, 12overline 4 ), 2.366(76)(22overline 6 , 3.1.overline 1 0, 32overline 3 ), 2.109(54)(42 33, 42 44, 51overline 9 , 414), 1.669(64)(2.2.overline 1 3, 3.2.overline 1 3, 62overline 3 , 6.1.overline 1 3), 1.614(56)(5.0.overline 1 6, 137, 333, 71overline 1 ). The infrared spectrum is given. Middendorfite is a phyllosilicate related to bannisterite, parsenttensite, and the minerals of the ganophyllite and stilpnomelane groups. The new mineral is named in memory of A.F. von Middendorff (1815 1894), an outstanding scientist, who carried out the first mineralogical investigations in the Khibiny pluton. The type material of middenforite has been deposited at the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.

  8. An Investigation on Soil Chemical Composition and Shallow Groundwater Condition in a Saline Area in Nakhon Panom Province, Thailand

    NASA Astrophysics Data System (ADS)

    Seeboonruang, U.

    2010-12-01

    The Mekong River Basin region is a potential salt-accumulated neighborhood. Several subbasin areas have been reported to have the saline soil problem and these include Lower Songkram River, Nam Oon Brook, Nam Thew Brook, and Namkam Brook. The study area is located on the lower of the Namkam River Basin mainly in 3 districts of the Nakhon Panom Province and these districts are Amphoe That Panom, Amphoe Nakae, and Amphoe Renu Nakhon. Soil salinity is found risen sparsely in some villages of these three districts. Generally, shallow groundwater is known to facilitate the distribution of dissolved salts away from the salinity sources and to pick up the salts to the top soils. Thus, groundwater plays a major role in salinity distribution everywhere. The objective of this research is to investigate the soil chemical composition and shallow groundwater evolution in the study area. Soil samples are analyzed using X-Ray Fluorescence Spectrometer (XRF). The depth to groundwater, groundwater pH, total dissolved solids (TDS), electrical resistivity (EC), and salinity are the parameters and the measurement takes place from October 2007 to present. There are 19 sampling locations distributed in the study area. The depth of the observation wells varies from 4 m to 40 m. Groundwater table is found to be up to 7 m below the groundwater surface and the depth is increasing from December to April. Groundwater pH is constantly less than 7 and greater than 4. Groundwater pH varies significantly between 10 mg/l to 45,000 mg/l and EC also differs between 10 µS/cm to 90,000 µS/cm. Most of groundwater sampled in the study area is slight blackish with salinity measured below 1.00 ppt and these are Ban Don Dang, Ban Wang Yang, Ban Na Khu, Ban Piman Ta, Pan Sala, and Ban Lao Tung. On the other hand, Ban Bo Dong Sorn and Ban Pra Song Noi have very saline shallow groundwater with salinity greater 1ppt. The results from the XRF show that SiO2 and Al2O3 are the main composition and the soil is made up of SiO2 more than 50% and Al2O3 more than 15%. The minor chemical elements are Fe2O3, K2O, MgO, CaO, SO3, TiO2, Cl, CuO, and MnO. The percentages of these elements on the average are as following 8, 5, 5, 4, 3, 2, 0.7, 0.2, and 0.2, respectively. The soil sample from one of the salt pits is composed of Na2O almost 60% and Cl more than 30%.

  9. Friedrichbeckeite, K (?0.5Na0.5)2 (Mg0.8Mn0.1Fe0.1)2 (Be0.6 Mg0.4)3 [Si12O30], a new milarite-type mineral from the Bellerberg volcano, Eifel area, Germany

    NASA Astrophysics Data System (ADS)

    Lengauer, C. L.; Hrauda, N.; Kolitsch, U.; Krickl, R.; Tillmanns, E.

    2009-07-01

    Friedrichbeckeite is a new milarite-type mineral. It was found in a single silicate-rich xenolith from a quarry at the Bellerberg volcano near Ettringen, eastern Eifel volcanic area, Germany. It forms thin tabular crystals flattened on {0001}, with a maximum diameter of 0.6 mm and a maximum thickness of 0.1 mm. It is associated with quartz, tridymite, augite, sanidine, magnesiohornblende, enstatite, pyrope, fluorapatite, hematite, braunite and roedderite. Friedrichbeckeite is light yellow, with white to light cream streak and vitreous lustre. It is brittle with irregular fracture and no cleavage, Mohs hardness of 6, calculated density is 2.686 gcm-3. Optically, it is uniaxial positive with n? = 1.552(2) and n? = 1.561(2) at 589.3 nm and a distinct pleochroism from yellow (//?) to light blue (//?). Electron microprobe analyses yielded (wt.%): Na2O 2.73, K2O 4.16, BeO 4.67, MgO 11.24, MnO 2.05, FeO 1.76, Al2O3 0.15, SiO2 73.51, (? CaO, TiO2 = 0.06) sum 100.33 (BeO determined by LA-ICP-MS). The empirical formula based on Si = 12 is K0.87 Na0.86 (Mg1.57Mn0.28Fe0.24)?2.09 (Be1.83 Mg1.17)?3.00 [Si12O30], and the simplified formula can be given as K (?0.5Na0.5)2 (Mg0.8Mn0.1Fe0.1)2 (Be0.6 Mg0.4)3 [Si12O30]. Friedrichbeckeite is hexagonal, space-group P6/ mcc, with a = 9.970(1), c = 14.130(3) Å, V = 1216.4(3) Å3, and Z = 2. The strongest lines in the X-ray powder diffraction pattern are ( d in Å / I obs / hkl): 3.180 / 100 / 121, 2.885 / 70 / 114, 4.993 / 30 / 110, 4.081 / 30 / 112, 3.690 / 30 / 022. A single-crystal structure refinement ( R1 = 3.62 %) confirmed that the structure is isotypic with milarite and related [12] C [9] B 2 [6] A 2 [4] T23 [[4] T112O30] compounds. The C-site is dominated by potassium, the B-site is almost half occupied by sodium, and the A-site is dominated by Mg. The site-scattering at the T2-site can be refined to a Be/(Be + Mg) value close to 0.61; the T1-site is occupied by Si. Micro-Raman spectroscopy reveals an increasing splitting of scattering bands around 550 cm-1 for friedrichbeckeite. The mineral can be classified as an unbranched ring silicate or as a beryllo-magnesiosilicate. With respect to the end-member formula K (?0.5Na0.5)2 Mg2 Be3 [Si12O30] friedrichbeckeite represents the Mg-dominant analogue of almarudite, milarite or oftedalite. The mineral and its paragenesis were formed during pyrometamorphic modifications of the silicate-rich xenoliths enclosed in Quaternary leucite-tephritic lava of the Bellerberg volcano. Holotype material of friedrichbeckeite has been deposited at the mineral collection of the Naturhistorisches Museum Wien, Austria. The mineral is named friedrichbeckeite in honour of the Austrian mineralogist and petrographer Friedrich Johann Karl Becke (1855-1931).

  10. Mineralized and Barren Tourmaline Breccia at Río Blanco-Los Bronces Copper Deposit, Central Chile

    NASA Astrophysics Data System (ADS)

    Hohf, Michael; Seifert, Thomas; Ratschbacher, Lothar; Rabbia, Osvaldo; Krause, Joachim; Haser, Sabine; Cuadra, Patricio

    2014-05-01

    The Río Blanco-Los Bronces porphyry copper-molybdenum cluster (14.8-4.3 Ma) in central Chile is one of the largest mining districts of the world with more than 200 Mt of contained Cu; almost 30% of these resources are hosted by hydrothermal breccias. These breccia complexes are tourmaline-, biotite-, chlorite-, or iron oxide-cemented and are widespread in the Paleo-Eocene and Mio-Pliocene porphyry Cu-Mo belt of the central Andes. The ongoing research project aims to understand the time-space relationships between the different breccia bodies and the multiple porphyry intrusions. For this, two cross sections in the southern part of the deposit (Sur-Sur and La Americana areas) are studied. Most interesting from the economic/genetic point of view is the intermineral breccia (tourmaline- and biotite-cemented), which have high copper grades. It is under debate whether there is a vertical mineralogical zonation of the cement of the breccia body from tourmaline-rich at the top to biotite-dominated at the bottom, or there are two superimposed breccia formation events. Textural and mineralogical observations of benches- and tunnels-outcrops, drill cores, and polished-thin sections support the first hypothesis. Our work has been focused on tourmaline chemistry due to its high resistance to alteration and weathering, which allows this mineral to retain its original isotopic signature. Preliminary results of 127 microprobe measurements of tourmaline chemistry from the early mineralized breccia (BXT) and the late barren one (BXTTO) show that all the tourmalines belong to the alkali group and the composition ranges between the dravite-schorl end members. There is a pronounced negative correlation between Fe (ferric?) and Al, probably due to exchange at the Z octahedral position. The backscatter images of tourmaline show oscillatory and sector zonings, i.e., alternating light bands/zones (high CaO, FeO, Na2O) and darker ones (enriched in Al2O3 and MgO). There is no significant difference between the concentrations of the major constituent elements (SiO2, Al2O3, FeO, MgO), but a slight enrichment of TiO2 is recognized in the BXTTO. Previous works attempted to determine the age of the brecciation-mineralization event, dating sericite and biotite. The ages were interpreted to record thermal resetting of the K-Ar system by later intrusions. Therefore, we are attempting Ar-Ar dating of tourmaline (closure temperature ~600° C) albeit it's low K2O contents (average 0.04 wt. %). We will complement the tourmaline major element measurements (EMPA) with minor and trace elements data (LA-ICPMS) to find some discriminating factor between fertile and barren crystallization environment. We are also conducting B-isotopic analyses to identify the source/s of boron in these fluids (magmatic vs non-magmatic -evaporitic- origin).

  11. Geochemistry and petrogenesis of lamproites, late cretaceous age, Woodson County, Kansas, U.S.A.

    USGS Publications Warehouse

    Cullers, R.L.; Ramakrishnan, S.; Berendsen, P.; Griffin, T.

    1985-01-01

    Lamproite sills and their associated sedimentary and contact metamorphic rocks from Woodson County, Kansas have been analyzed for major elements, selected trace elements, and strontium isotopic composition. These lamproites, like lamproites elsewhere, are alkalic (molecular K2O + Na2O Al2O3 = 1.6-2.6), are ultrapotassic ( K2O Na2O = 9.6-150), are enriched in incompatible elements (LREE or light rare-earth elements, Ba, Th, Hf, Ta, Sr, Rb), and have moderate to high initial strontium isotopic compositions (0.7042 and 0.7102). The silica-saturated magma (olivine-hypersthene normative) of the Silver City lamproite could have formed by about 2 percent melting of a phlogopite-garnet lherzolite under high H2O CO2 ratios in which the Iherzolite was enriched before melting in the incompatible elements by metasomatism. The Rose Dome lamproite probably formed in a similar fashion although the extreme alteration due to addition of carbonate presumably from the underlying limestone makes its origin less certain. Significant fractional crystallization of phases that occur as phenocrysts (diopside, olivine, K-richterite, and phlogopite) in the Silver City magma and that concentrate Co, Cr, and Sc are precluded as the magma moved from the source toward the surface due to the high abundances of Co, Cr, and Sc in the magma similar to that predicted by direct melting of the metasomatized Iherzolite. Ba and, to a lesser extent, K and Rb and have been transported from the intrusions at shallow depth into the surrounding contact metamorphic zone. The Silver City lamproite has vertical fractionation of some elements due either to volatile transport or to variations in the abundance of phenocrysts relative to groundmass most probably due to flow differentiation although multiple injection or fractional crystallization cannot be conclusively rejected. ?? 1985.

  12. Jurassic-Cretaceous clastic sequences of Chukotka: sedimentation, structural style and geodynamic implications for Russian East Arctic shelf.

    NASA Astrophysics Data System (ADS)

    Tuchkova, M. I.; Sokolov, S. D.; Verzhbitsky, V. E.

    2009-04-01

    Jurassic-Lower Cretaceous sedimentary sequence, exposed on the Chukotka continental margin is critical for understanding the timing, dynamics and sedimentary setting evolution of Chukotka-Eurasia collisional process (e.g., Sokolov et al., 2002) and so, represents one of the key regional stratigraphic units (Til'man,1973, Tibilov,1982; Miller et al., 2002, 2007). From the other hand, this research may shed the light on the widely discussing problem of the Canadian and Makarov basins opening (e.g., Miller, Verzhbitsky, in press). Jurassic-Lower Cretaceous sedimentary complexes of the Chukotka microcontinent are composed of terrigeneous deposites. Those sedimentary complexes are enriched by organic matter, and fresh clastic materials. Fragments of shales, sometimes laminated or cleaved are their indicator constituents. Sandstones are arkosic. The percentage of types of rocks fragments is different in Jurassic and Cretaceous deposits. Chemical composition of the Jurassic-Cretaceous rocks is not uniform too: Upper Jurassic sandstones form one group depleted in Na2O+K2O, Cretaceous sandstones, enriched in Na2O+K2O. Thus, our investigations indicate that Jurassic-Cretaceous sedimentary basins were related to different source provenance. We believe, that the stratigraphy and composition of Jurassic-Lower Cretaceous onshore sequences are crucial for prediction of the geological structure of East Siberian and Chukchi Sea shelf (1), understanding the evolution of Mesozoic sedimentary basins of East Arctic (2) and testifying the existing geodynamic models of Amerasian Basin opening (3). The work is supported by the Russian Foundation for Basic Research (grant 08-05-00547), program of ONZ RAS 14, and NSH-3172.2008.5.

  13. Iron-phosphate glass fiber scaffolds for the hard-soft interface regeneration: the effect of fiber diameter and flow culture condition on cell survival and differentiation.

    PubMed

    Bitar, Malak; Salih, Vehid; Knowles, Jonathan C; Lewis, Mark P

    2008-12-15

    This work investigated the further development of a well-characterized, contiguous, glass fiber system for regeneration of the hard-soft tissue interface. We evaluated the effect of fiber diameter on human osteoblasts and fibroblasts attachment and viability using ternary glass fibers of the composition 0.48 CaO-0.02 Na(2)O-0.50 P(2)O(5). Fiber diameter significantly influenced cell attachment and survival, with fibers drawn at 800 revolutions per minute found to be optimal. Using a known composition of iron-phosphate glass fibers (composition 0.46 CaO-0.01 Na(2)O-0.03 Fe(2)O(3)-0.50 P(2)O(5)), scaffolds were produced. These scaffolds were incorporated within an open laminar flow culture system to provide nutrients, oxygen, and waste perfusion throughout the culture. The design of the chamber ensured that laminar flow was present, and changes in the differentiation of both osteoblast and fibroblast seeded scaffolds were assessed using quantitative polymerase chain reaction. Our data show that osteoblast and fibroblast differentiation is unaffected or enhanced by laminar flow when compared with static culture conditions. This system can therefore be adapted to construct larger, more complex, three-dimensional iron-phosphate fiber scaffolds for tissue engineering. PMID:18257069

  14. Geochemistry of Lower Cretaceous strata of northern Priverkhoyansk Foreland Basin (NE SIBERIA): implications for provenance

    NASA Astrophysics Data System (ADS)

    Vasiliev, Dmitry; Ershova, Victoria; Ivensen, Galina; Prokopiev, Andrei

    2014-05-01

    The study area is located in the lower reaches of the Lena R., in between Chekurovka and Chucha Capes. The Lower Cretaceous clastic rocks of the northern part of the Priverkhoyansk foreland basin adjacent to the front of the Verkhoyansk fold-and-thrust belt have been studied. The Lower Cretaceous sections are composed of marine and fluvial terrigenous rocks. Marine deposits are represented by alternating sandstones and siltstones, while continental ones by alternating thick sandstones units (up to 400 m) and shale units with subordinate sandstones beds. The thickness of studied strata varies from 800-1900 m. The whole-rock geochemical analyses were done for 121 samples The geochemical study show: 1) uniform, persistent chemical composition close to that of acid igneous rocks; 2) low TiO2 content; 3) low MgO and FeO* values; 4) prevalence of FeO over Fe2O3 ; 5) high alkalies content with prevailing Na2O; 6) positive correlation between TiO2 and FeO* contents and negative correlation between Na2 O+K2 O and FeO* values. The data point to the same source of sediments both for marine and fluvial deposits with prevailing felsic rocks in provenance area. This research was supported by RFBR grants 14-05-31298, 13-05-00700, 13-05-00943 research grant of Saint Petersburg State University and Grant of President of Russia for Young Scientist MK-2902.2013.5.

  15. K/Na ratio of Cenozoic igneous rocks of the western United States

    USGS Publications Warehouse

    Moore, J.G.

    1962-01-01

    The potassium and sodium content of chemically analysed Cenozoic igneous rocks from about 150 areas of the western United States has been examined. For each area a plot of the molecular proportion K2O (K2O + Na2O) [Niggli's k-value] is shown, and the projected k-value determined at 50 and 60 weight per cent SiO2. The k-values are plotted and contoured on maps of the western United States. These maps show that potassium is least abundant relative to total alkali (when rocks of the same SiO2 content are compared) in a zone along the Pacific Coast, becomes more abundant eastward, and is highest in the Colorado Plateau and Northern Rocky Mountains. These k-value variations can be related to regional variations in the abundance of certain trace elements and of different types of older granitic rocks, and to Bouguer gravity maps. This correspondence indicates that the alkali ratio of Cenozoic igneous rocks is closely related to the character of the crust where the rocks are formed. ?? 1962.

  16. Thermal behaviour of Fe-doped silicate–phosphate glasses

    Microsoft Academic Search

    Irena Wac?awska; Magdalena Szumera

    2010-01-01

    Thermal behaviour and structure of glasses from the SiO2–P2O5–K2O–MgO–CaO system modified by Fe2O3 addition were studied by DSC, XRD and FTIR methods. It has been found that the replacement of MgO and CaO modifiers by Fe2O3 in the structural network of silicate–phosphate glass results in decrease of the glass transition temperature (T\\u000a g) and heat capacity change (?C\\u000a p) accompanying

  17. Geochemical insights into the role of metasomatic hornblendite in generating alkali basalts

    NASA Astrophysics Data System (ADS)

    Dai, Li-Qun; Zhao, Zi-Fu; Zheng, Yong-Fei

    2014-10-01

    petrology suggested the role of hornblendite in generating alkali basalt. This mechanism is confirmed by an integrated study of major-trace elements and radiogenic isotopes for Mesozoic alkali basalts from the Qinling orogen in China. The alkali basalts have high contents of MgO (4.8-11.1 wt %, Mg# = 47-69), Na2O + K2O (2.9-5.4 wt %), TiO2 (2.0-3.1 wt %) but low content of SiO2 (41.4-49.6 wt %), which are generally silica-undersaturated with normative minerals of nepheline and olivine. They exhibit OIB-like trace element distribution patterns, with enrichment of LILE and LREE but no depletion of HFSE relative to the primitive mantle. They also show relatively depleted Sr-Nd-Hf isotope compositions, with low initial 87Sr/86Sr ratios of 0.7028-0.7058, positive ?Nd(t) values of 4.0-9.8 and ?Hf(t) values of 8.8-13.5 for whole-rock, and positive ?Hf(t) values of 5.2-16.4 for zircon. Such element and isotope features indicate their origination from the juvenile subcontinental lithospheric mantle (SCLM) source with involvement of crustal components. The alkali basalts generally have high K2O/Na2O ratios, and high K2O and TiO2 contents, suggesting their derivation from partial melting of hornblendite-rich mantle lithology. They also exhibit variable K/La and Ti/La ratios that are correlated with (La/Yb)N ratios, indicating a geochemical heterogeneity of the SCLM source. Taken together, all the above geochemical features can be accounted for by partial melting of a hornblendite-rich SCLM source. The hornblendite would be generated by reaction of the juvenile SCLM wedge peridotite with hydrous felsic melts derived from subducted Palaeotethyan oceanic crust at the slab-mantle interface in the subduction channel. Therefore, orogenic alkali basalts record recycling of the subducted fossil oceanic crust, and the metasomatic hornblendite is an important lithology in local SCLM domains above fossil subduction channels.

  18. Configuring Mixed Reality Environment Imran N. Junejo, Xiaochun Cao

    E-print Network

    Foroosh, Hassan

    of an arbitrary number of agents. Each agent consist of a head mounted display (HMD), which consists of a pair shows images of such a scenario. A video see-through HMD consist of small mounted cameras that capture the surrounding environment. On the inside of the HMD, the captured video is played to the user in real

  19. Doctoral candidate Hung Cao is working on creating

    E-print Network

    Chiao, Jung-Chih

    a high- powered laser. (The Shorthorn: Stephanie Goddard) Microscale technology used to create micro in depression. "Using this approach, maybe we can qualitatively pinpoint the problem," Chiao said. "It may and combinations to determine a treatment regimen. As well as diagnosis, this technology may be used to treat

  20. Fuzzy Identity Based Signature Piyi Yang, Zhenfu Cao 1

    E-print Network

    Abstract We introduce a new cryptographic primitive which is the signature analogue of fuzzy identity based certain attributes. Fuzzy IBS can also be applied to biometric identity based signature. To our best the definition and security model of the new primitive and present the first practical implementation based

  1. Antiphase synchronism in chaotic systems Ling-Yuan Cao1,

    E-print Network

    Lai, Ying-Cheng

    of Mathematics, The University of Kansas, Lawrence, Kansas 66045 2 Department of Physics and Astronomy, The University of Kansas, Lawrence, Kansas 66045 Received 14 October 1997 We report our finding and analysis

  2. Determinismo e caos: un antico dualismo oggi Giovanni Gallavotti

    E-print Network

    Roma "La Sapienza", Università di

    deter- ministica. Dapprima i moti delle stelle #12;sse quindi della Luna e delle sei stelle erranti. Lo pianeti maggiori (Marte,Giove Saturno) visto dalla Terra rispetto alle Stelle #12;sse: schema tolemaico

  3. EFFECTS OF LIME (CAO) ON THE ENDOTOXIN LEVELS OF BIOSOLIDS

    EPA Science Inventory

    Lime addition is a common practice for treating biosolids in order to meet EPA 503 requirements for land application. Since this treatment kills the majority of microorganisms, will it increase the level of endotoxins present in biosolids? And, if endotoxin levels are increased, ...

  4. Bioactivity of ferrimagnetic glass-ceramics in the system FeO-Fe2O3-CaO-SiO2.

    PubMed

    Ebisawa, Y; Miyaji, F; Kokubo, T; Ohura, K; Nakamura, T

    1997-10-01

    Bioactive and ferrimagnetic glass-ceramics are useful as thermoseeds for hyperthermia treatment of cancer. A heat treatment of a 40(FeO, Fe2O3)-60CaO x SiO2 wt% glass gives a ferrimagnetic glass-ceramic containing 36 wt% magnetite in a CaO x SiO2 matrix. However, it does not show bioactivity since a small amount of iron ion remains in the matrix. In the present study, bioactivities of ferrimagnetic glass-ceramics which were prepared by heat treatment of glasses of the composition 40(FeO, Fe2O3)-60CaO x SiO2 (wt%) with various components added at 100:3 weight ratio were evaluated in vitro by examining bone-like apatite formation on their surfaces in a simulated body fluid. It was found that glass-ceramics with Na2O or B2O3 added in combination with P2O5 show bioactivity. PMID:9307216

  5. Study on the preparation and properties of silver-doped phosphate antibacterial glasses (Part I)

    NASA Astrophysics Data System (ADS)

    Ahmed, A. A.; Ali, A. A.; Mahmoud, Doaa A. R.; El-Fiqi, A. M.

    2011-05-01

    Silver-doped phosphate antibacterial glasses were prepared by the melting method. The antibacterial effects of some undoped and silver-doped glasses of compositions 65P 2O 5-10CaO-(25- x) Na 2O, 70P 2O 5-20CaO-(10- x) Na 2Oand (70- x) P 2O 5-30CaO, (where x = 0, 0.5, 1.2 Ag 2O), against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli micro-organisms using agar disk-diffusion assays were investigated. The structures of some glasses were studied by XRD, FT-IR, and UV-VIS spectroscopy. The variation of pH with dissolution rate was studied. The tested silver-free and silver-doped glasses demonstrated different antibacterial effects against the tested micro-organisms. For silver-free glasses, an increase in inhibition zone diameter (zone of no bacterial growth) was seen with the decrease in water pH. Silver-doped glasses showed an increase in inhibition zone diameter with increasing Ag 2O content. The low pH produced by glass dissolution was certainly a critical factor for glass antibacterial effect. The more the phosphate ions released the lower is the pH and the greater the antibacterial effect.

  6. Formulation of humic-based soil conditioners

    NASA Astrophysics Data System (ADS)

    Amanova, M. A.; Mamytova, G. A.; Mamytova, B. A.; Kydralieva, K. A.; Jorobekova, Sh. J.

    2009-04-01

    The goal of the study is to prepare soil conditioners (SC) able to carry out the following functions: (i) the chemical conditioning of soil mainly comprising the adjustment of pH, (ii) the balancing of inorganic nutrients, (iii) the physical conditioning of soil mainly comprising the improvement of water permeability, air permeability and water retention properties, and (iv) improvement of the ecological system concerning of useful microorganisms activity in the soil. The SC was made of a mixture of inorganic ingredients, a chemical composition and physical and chemical properties of which promoted improvement of physical characteristic of soil and enrichment by its mineral nutritious elements. In addition to aforesaid ingredients, this soil conditioner contains agronomical-valued groups of microorganisms having the function promoting the growth of the crop. As organic component of SC humic acids (HA) was used. HA serve many major functions that result in better soil and plant health. In soil, HA can increase microbial and mycorrhizal activity while enhancing nutrient uptake by plant roots. HA work as a catalyst by stimulating root and plant growth, it may enhance enzymatic activity that in turn accelerates cell division which can lead to increased yields. HA can help to increase crop yields, seed germination, and much more. In short, humic acids helps keep healthy plants health. The first stage goal was to evaluate mineral and organic ingredients for formulation of SC. Soil conditioners assessed included ash and slag. The use of slags has been largelly used in agriculture as a source of lime and phosphoric acid. The silicic acid of slags reduces Al-acitivity thus, promoting a better assimilation of P-fertilizer by plants. Additionally, silicic acid is also known to improve soil moisture capacity, thus enhancing soil water availability to plants. Physico-chemical characteristics of ash and slag were determined, as a total - about 20 samples. Results include: Chemical composition of (i) ash: 53-54% SiO2; 26-27% Al2O3; 3-5% Fe2O3; 1.7-2.9% CaO; 1.3-2.3% MgO; 0.5-0.8% Na2O; 1.0-1.5% K2O and; (ii), slag: 17-20% SiO2; 15-20% Al2O3; 30-40% CaO; 1-6% Fe2O3; 4-11% MgO. Of all samples assessed, per 5 samples from various regions with various compositions (high, average and low content of metal oxides) were selected and tested as component of SC in vegetative pot and field experiments, i.e., to study the immobilization processes including microorganisms and inorganic ingredients. This study helped to elucidate the influence of ash and slag composition on microbial development. The next stage was (i) to evaluate microbial activity of selected soils from Kyrgyzstan, (ii) to isolate microorganisms exhibiting antagonistic activity against pathogenic microorganisms present in the soil and, (iii) to utilize microbes as nutrient sources. Candidate microbial cultures were isolated from soils/crops and assessed as plant growth promoting microorganisms. The characteristics of the physiological groups of microorganisms were also investigated. Of different physiological groups of microorganisms selected, ca, 3 consortia of agronomical-valued microbial groups from undisturbed soils was selected as component of soil conditioners. Microorganisms, namely oligonitrophils, ammonifiers, nitrifiers, were tested based on beneficial bioactivity including plant biomass and stem length on commercial onion and lettuce crops. Our results demonstrate that all the combinations ash/slag, humic acids and consortium of beneficial agronomical-valued microbial groups into one environmentally friendly soil conditioner possessed equal or higher growth-promoting potential in relation to lettuce. However, our results demonstrated clearly that among studied scope of soil conditioners only one of them could be recommended for further study in terms of practical applications. Namely, it was mixture consisting of humic acids, ash and oligonitrophils as soil conditioning agent. Acknowledgement. This research was supported by the grant of ISTC KR-993.2.

  7. Tourmaline (dravite) from the Boehls Butte anorthosite, Idaho, U.S.A.

    USGS Publications Warehouse

    Hietanen, A.

    1987-01-01

    Greenish black tourmaline occurs in small localized masses in the Boehls Butte layered, two-plagioclase anorthosite. Chemical analysis by S. Neil gave SiO2 36.6, TiO2 0.34, B2O3 10.7, Al2O3 33.6, V2O3 0.24, FeO 4.16, MnO 0.09, MgO 8.04, CaO 0.98, Na2O 1.74, F 0.03, H2O+ 3.06, less O = F 0.01, = 99.57; epsilon (pale reddish brown) 1.62, omega (brownish green) 1.647; a 15.9425, c 7.1883 A.-R.A.H.

  8. Effect of Boron Addition on the Thermal, Degradation, and Cytocompatibility Properties of Phosphate-Based Glasses

    PubMed Central

    Hasan, Muhammad S.; Parsons, Andrew J.; Furniss, David; Scotchford, Colin A.; Ahmed, Ifty; Rudd, Chris D.

    2013-01-01

    In this study eight different phosphate-based glass compositions were prepared by melt-quenching: four in the (P2O5)45-(CaO)16-(Na2O)15-x -(MgO)24-(B2O3)x system and four in the system (P2O5)50-(CaO)16-(Na2O)10-x-(MgO)24-(B2O3)x, where x = 0,1, 5 and 10?mol%. The effect of B2O3 addition on the thermal properties, density, molar volume, dissolution rates, and cytocompatibility were studied for both glass systems. Addition of B2O3 increased the glass transition (Tg), crystallisation (Tc), melting (Tm), Liquidus (TL) and dilatometric softening (Td) temperature and molar volume (Vm). The thermal expansion coefficient (?) and density (?) were seen to decrease. An assessment of the thermal stability of the glasses was made in terms of their processing window (crystallisation onset, Tc,ons minus glass transition temperature, Tg), and an increase in the processing window was observed with increasing B2O3 content. Degradation studies of the glasses revealed that the rates decreased with increasing B2O3 content and a decrease in degradation rates was also observed as the P2O5 content reduced from 50 to 45?mol%. MG63 osteoblast-like cells cultured in direct contact with the glass samples for 14 days revealed comparative data to the positive control for the cell metabolic activity, proliferation, ALP activity, and morphology for glasses containing up to 5?mol% of B2O3. PMID:23991425

  9. The Easternmost Southwest Indian Ridge: A Laboratory to Study MORB and Oceanic Gabbro Petrogenesis in a Very Low Melt Supply Context

    NASA Astrophysics Data System (ADS)

    Paquet, M.; Cannat, M.; Hamelin, C.; Brunelli, D.

    2014-12-01

    Our study area is located at the ultra-slow Southwest Indian Ridge, east of the Melville Fracture Zone, between 61 and 67°E. The melt distribution in this area is very heterogeneous, with corridors of ultramafic seafloor where plate separation is accommodated by large offset normal faults [Sauter, Cannat et al., 2013]. These ultramafic corridors also expose rare gabbros and basalts. We use the major and trace elements composition of these magmatic rocks to document the petrogenesis of MORB in this exceptionnally low melt supply portion of the MOR system. Basalts from the easternmost SWIR represent a global MORB end-member for major element compositions [Meyzen et al., 2003], with higher Na2O and Al2O3 wt%, and lower CaO and FeO wt% at a given MgO. Within this group, basalts from the ultramafic corridors have particularly high Na2O, low CaO and FeO wt%. Best fitting calculated liquid lines of descent are obtained for crystallization pressures of ~8 kbar. Gabbroic rocks recovered in the ultramafic corridors include gabbros, oxide-gabbros and variably impregnated peridotites. This presentation focuses on these impregnated samples, where cpx have high Mg#, yet are in equilibrium with the nearby basalts in terms of their trace element compositions. Plagioclase An contents vary over a broad range, and there is evidence for opx resorption. These characteristics result from melt-mantle interactions in the axial lithosphere, which may explain several peculiar major element characteristics of the basalts. Similar interactions probably occur beneath ridges at intermediate to slow and ultraslow spreading rates. We propose that they are particularly significant in our study area due to its exceptionnally low integrated melt-rock ratio.

  10. Formation of corundum in metapelites around ultramafic bodies. An example from the Saualpe region, Eastern Alps

    NASA Astrophysics Data System (ADS)

    Riesco, M.; Stüwe, K.; Reche, J.

    2005-01-01

    This paper describes corundum formation in a metasomatic reaction zonation around an ultramafic body within a metapelitic sequence. The investigated body is about 100 m in diameter and is located in the Saualpe of the Austroalpine nappe complex in the Eastern Alps. The body is surrounded by a 10 m wide reaction zone (here called zone 3) containing the paragenesis garnet staurolite biotite margarite chlorite corundum. Beyond a further metasomatic transition zone (here called zone 2), there are undisturbed metapelitic host rocks (zone 1) that have the metamorphic peak paragenesis garnet biotite plagioclase staurolite muscovite quartz. It is shown that reaction zonation formed around 7.2 kbar and 615 °C during regional metamorphism, just above the serpentine breakdown reactions in the system MgO SiO2 H2O. Detailed analysis of the whole rock compositions shows that the reaction zonation formed by infiltration metasomatism that caused significant mass loss in the two alteration zones. These zones are particularly depleted in SiO2, Na2O and possibly K2O. An XNa2O XSiO2 thermodynamic pseudosection is presented that includes the parageneses of both the unaltered metapelitic host rock and the corundum-bearing parageneses. This suggests that the metasomatic process can be explained by the transfer of SiO2 and Na2O alone. We interpret that the process is driven by water liberated from the previously serpentinised ultramafic body during prograde dehydration during regional Eo-Alpine metamorphism. This fluid flowed outwards from the ultramafic body depleting the surrounding pelites in silica and causing margarite formation from plagioclase and muscovite. This interpretation of the driving mechanism is consistent with our knowledge of the low water activities of the Saualpe during the Eo-Alpine orogenic cycle.

  11. The Ca-Eskola component in eclogitic clinopyroxene as a function of pressure, temperature and bulk composition: an experimental study to 15 GPa with possible implications for the formation of oriented SiO2-inclusions in omphacite

    NASA Astrophysics Data System (ADS)

    Konzett, Jürgen; Frost, Daniel J.; Proyer, Alexander; Ulmer, Peter

    2008-02-01

    Experiments have been conducted in the P-T range 2.5-15 GPa and 850-1,500°C using bulk compositions in the systems SiO2-TiO2-Al2O3-Fe2O3-FeO-MnO-MgO-CaO-Na2O-K2O-P2O5 and SiO2-TiO2-Al2O3-MgO-CaO-Na2O to investigate the Ca-Eskola (CaEs Ca0.5?0.5AlSi2O6) content of clinopyroxene in eclogitic assemblages containing garnet + clinopyroxene + SiO2 ± TiO2 ± kyanite as a function of P, T, and bulk composition. The results show that CaEsss in clinopyroxene increases with increasing T and is strongly bulk composition dependent whereby high CaEs-contents are favoured by bulk compositions with high normative anorthite and low diopside contents. In this study, a maximum of 18 mol% CaEsss was found at 6 GPa and 1,350°C in a kyanite-eclogite assemblage garnet + clinopyroxene + kyanite + rutile + coesite. By comparison, no significant increase in CaEsss with increasing P could be observed. If the formation of oriented SiO2-rods frequently observed in eclogititc clinopyroxenes is due to the retrogressive breakdown of a CaEs-component then these textures are a cooling rather than a decompression phenomenon and are most likely to be found in kyanite-bearing eclogites cooled from temperatures ?750°C. The presence of clinopyroxene with approx. 4 mol% CaEsss in an experiment conducted at 2.5 GPa/850°C confirms earlier suggestions based on field data that vacancy-rich clinopyroxenes are not necessarily restricted to ultrahigh pressure metamorphic conditions.

  12. Late Mesozoic time constraints on tectonic changes of the Luanchuan Mo belt, East Qinling orogen, Central China

    NASA Astrophysics Data System (ADS)

    Li, Dong; Zhang, Shou-Ting; Yan, Chang-Hai; Wang, Gong-Wen; Song, Yao-Wu; Ma, Zhen-bo; Han, Jiang-wei

    2012-10-01

    Two late Mesozoic granitoids in the Luanchuan area of the East Qinling orogen are considered; ore-bearing rocks are granite porphyries and granodiorite, with K2O > Na2O, appearing in the form of stocks. The Laojunshan rocks contains dominantly monzonitic granite, with K2O ? Na2O, in the form of a batholith. Both the ore-bearing rocks and the Laojunshan rocks are highly siliceous and shoshonitic, high-K calc-alkaline, similar to some I-type granites. Light rare earth elements (LREEs) are enriched in both rock suites, although the Luanchuan ore-bearing granitoids have higher concentrations, with (La/Yb)N ratios twice that of the barren Laojunshan granite suite. Ore-bearing rocks have, therefore, undergone greater fractionation of heavy rare earth elements. All Laojunshan rocks have negative Eu anomalies, indicating plagioclase fractionation. ?Eu values are different in both rock suites, the values in the ore-bearing granites, ranging from 0.52 to 1.04, which are much higher than that of Laojunshan batholith, ranging from 0.4 to 0.65. (La/Sm)N values of ore-bearing granites are 5.32-8.28, while that of Laojunshan batholith are 3.75-5.77, confirming the observation that the ore-bearing granites have undergone a higher degree of strong differentiation than that of Lanjunshan batholith. Major and trace element data, and REE data, combined with isotope data from previous work and the close relationships between the tectonic settings of the barren and ore-bearing rocks indicate that both groups of rocks were derived from the lower crust. At ˜157 Ma, with the tectonic regime in transition from a syn-collisional to a post-collisional setting, highly fractionated granites ascended from their storage area via faults; at ˜145 Ma, ore-bearing plutons, which are triggered by slab melts, formed at the junctions of fault planes trending WNW-ESE and NE-SW. At ˜115 Ma, the tectonic regime changed from compression to extension; in this environment, the barren Laojunshan batholith was emplaced, representing the end of the collisional event.

  13. Zircon U-Pb dating, geochemical and Sr-Nd-Pb isotopic compositions of shoshonitic intrusions, Western Alborz, NW Iran: petrogenesis and tectonic implications

    NASA Astrophysics Data System (ADS)

    Honarmand, Maryam; Nabatian, Ghasem; Jiang, Shao Yang

    2015-04-01

    The petrological and geochronological study of the Large-scale Cenozoic intrusions in the Tarom area reveals important clues to interpret complex relations between magmatic and tectonic processes in the central part of the Tethyan (Alpine-Himalayan) orogenic belt. New data, including field relations, U-Pb zircon geochronology and whole rock isotopic and geochemical features, come from four intrusions with monzodiorite, monzonite, quartzmonzonite and monzogranite compositions that form the Tarom Olya pluton, which forms part of the Western Alborz magmatic belt. LA-ICP-Ms analysis of zircons gives ages from 35.71 ±0.80 Ma to 37.7 ±0.52 Ma for magma pulses. The SiO2 contents of intrusions range from 57 to 69 wt.%, the K2O + Na2O content is high (5.5-10.3 wt.%) and K2O/Na2O ratio ranges from 0.9 to 2.0. Geochemical investigations show I-type and shoshonitic features as well post-collisional tectonic settings for studied samples. All the investigated rocks are enriched in light rare earth elements (LREEs), large ion lithophile elements (LILEs) and depleted in high field strength elements (HFSEs), and bear a weak Eu anomaly (Eu/Eu* = 0.56 to 0.9) in chondrite-normalized trace element patterns. Moreover, trace elements show some of the typical signatures of arc magmatism such as depletion in Nb, Ta and Ti. The samples display some variety in initial Sr and Nd isotopic compositions, marked with low ISr = 0.704-0.705 and ?Nd (36 Ma) = +0.9 to +2.1 values. The Pb isotopic ratios are (206Pb/204Pb) = 18.7-18.8, (207Pb/204Pb) = 15.58-15.61 and (208Pb/204Pb) = 38.72-38.90 Geochemical and isotopic data suggest that Neotethyan subduction metasomatized the mantle source by fluxing the fluids and melts from the slab zone and then lithosphere extension caused decompression melting and producing K-rich magmatism that formed the Tarom Olya intrusions, as well as other Eocene high potassic magmas of the Alborz magmatic belt.

  14. The geochemical nature of the Archean Ancient Gneiss Complex and Granodiorite Suite, Swaziland: a preliminary study

    USGS Publications Warehouse

    Hunter, D.R.; Barker, F.; Millard, H.T., Jr.

    1978-01-01

    The Ancient Gneiss Complex (AGC) of Swaziland, an Archean gray gneiss complex, lies southeast and south of the Barberton greenstone belt and includes the most structurally complex and highly metamorphosed portions of the eastern Kaapvaal craton. The AGC is not precisely dated but apparently is older than 3.4 Ga. The AGC consists of three major units: (a) a bimodal suite of closely interlayered siliceous, low-K gneisses and metabasalt; (b) homogeneous tonalite gneiss; and (c) interlayered siliceous microcline gneiss, metabasalt, and minor metasedimentary rocks - termed the metamorphite suite. A geologically younger gabbro-diorite-tonalite-trondhjemite suite, the Granodiorite Suite, is spatially associated with the AGC and intrusive into it. The bimodal suite consists largely of two types of low-K siliceous gneiss: one has SiO2 14%, low Rb/Sr ratios, and depleted heavy rare earth elements (REE's); the other has SiO2 > 75%, Al2O3 < 13%, high Rb/Sr ratios, and relatively abundant REE's except for negative Eu anomalies. The interlayered metabasalt ranges from komatiitic to tholeiitic compositions. Lenses of quartz monzonitic gneiss of K2O/Na2O close to 1 form a minor part of the bimodal suite. Tonalitic to trondhjemitic migmatite locally is abundant and has major-element abundances similar to those of non-migmatitic varieties. The siliceous gneisses of the metamorphic suite show low Al2O, K2O/Na2O ratios of about 1, high Rb/Sr ratios, moderate REE abundances and negative Eu anomalies. K/Rb ratios of siliceous gneisses of the bimodal suite are very low (???130); of the tonalitic gneiss, low (???225); of the siliceous gneiss of the metamorphite suite, moderate (???300); and of the Granodiorite Suite, high (???400). Rocks of the AGC differ geochemically in several ways from the siliceous volcanic and hypabyssal rocks of the Upper Onverwacht Group and from the diapirs of tonalite and trondhjemite that intrude the Swaziland Group. ?? 1978.

  15. New Insights into the Lithospheric Mantle Carbon Storage in an Intra-Continental Area: A Geochemical and 3D X-Ray Micro-Tomography Study

    NASA Astrophysics Data System (ADS)

    Creon, L.; Rouchon, V.; Rosenberg, E.; Delpech, G.; Youssef, S.; Guyot, F. J.; Szabo, C.

    2014-12-01

    The Pannonian Basins situated in a context of lithospheric fluxing by mantle CO2-rich fluids, as evidenced by Plio-Pleistocene alkaline basalts and Basin gas geochemical data [1]. Such type of intracontinental CO2-fluxes remain poorly constrained at the scale of the global C-cycle. We report here the first quantification of the CO2 volumes stored in the lithospheric mantle, by coupling geochemical and 3D micro-tomography studies of lherzolitic and harzburgitic mantle xenoliths. The Pannonian Basin xenolith peridotites present numerous signs of melt/fluid migration. The compositions of glasses found in the peridotites vary from sub-alkaline (Na2O + K2O = 3.8 wt. %) to alkaline (Na2O + K2O = 12.6 wt. %) and from mafic (SiO2 = 48.2 wt. %) to more felsic (SiO2 = 62.1 wt. %) compositions and differ markedly from the host basalts of the xenoliths. Microthermometric and Raman spectroscopic studies on fluid inclusions (n = 115) show pure CO2 compositions with densities range between 0.6 and 0.9 g.cm3 [290 to 735 MPa (PCO2)], corresponding to deep fluid trapping on both sides of the Moho. High-resolution synchrotron X-ray micro-tomography (Micro-CT), together with laboratory micro-CT were performed to obtain information about structure, volume and density of each phase (minerals, melts and fluids). Fluids and melts are mainly located at grain boundaries and secondary trails cut off the grain boundaries, which implies a contemporary introduction of such fluids [Figure 1]. The amount of fluid inclusions in xenoliths is heterogeneous and varied from 0.79 ± 0.15 to 4.58 ± 0.54 vol % of the peridotite. The carbon-dioxide content stored in the lithospheric mantle, due to the percolation of asthenospheric melts produced in the mantle beneath the Pannonian Basin, can be estimated by the combination of 3D reconstruction (Micro-CT) and CO2 pressures from inclusions. [1] B. Sherwood Lollar et al., 1997. Geochim. Cosmochim. Acta, vol. 61, no. 11, pp. 2295-2307

  16. Eruptive history, petrology, and petrogenesis of the Joe Lott Tuff Member of the Mount Belknap Volcanics, Marysvale volcanic field, west-central Utah

    USGS Publications Warehouse

    Budding, Karin E.

    1982-01-01

    The Joe Lott Tuff Member of the Mount Belknap Volcanics is the largest rhyolitic ash-flow tuff sheet in the Marysvale volcanic field. It was erupted 19 m.y. ago, shortly after the changeover from intermediate-composition calc-alkalic volcanism to bimodal basalt-rhyolite volcanism. Eruption of the tuff resulted in the formation of the Mount Belknap Caldera whose pyroclastic intracaldera stratigraphy parallels that in the outflow facies. The Joe Loft Tuff Member is a composite ash-flow sheet that changes laterally from a simple cooling unit near the source to four distinct cooling units toward the distal end. The lowest of these units is the largest and most widespread; it is 64 m thick and contains a basal vitrophyre. Eruption of the lower unit led to the initial collapse of the caldera. The lower unit is followed upward by a 43 m middle unit, a 26 m pink-colored unit which is separated by a prominent air- fall layer, and a 31 m upper unit. The Joe Loft Tuff Member is an alkali rhyolite with 75.85-77.31 wt. % silica and 8.06-9.32 wt. % K2O+Na2O; the agpaitic index (Na2O+ K2O/Al2O3) is .77-.98. The tuff contains about I% phenocrysts of quartz, sanidine, oligoclase, augite, apatite, zircon, sphene, biotite, and oxidized Fe-Ti oxides. The basal vitrophyre contains accessory allanite, chevkinite, and magnesiohastingsite. The main cooling units are chemically and mineralogically zoned indicating that the magma chamber restratified prior to each major eruption. Within each of the two thickest cooling units, the mineralogy changes systematically upwards; the Or content and relative volume of sanidine decreases and An content of plagioclase increases. The basal vitrophyre of the lower unit has a bulk composition that lies in the thermal trough near the minima of Or-Ab-Q at 1 kb PH2O. Microprobe analyses of feldspar and chemical modeling on experimental systems indicate that pre-eruption temperatures were near 750?C and that the temperature increased during the eruption of the cooling units. The chemical gradients in the apatite and whole-rock data in the Joe Loft Tuff Member and the consistent mineral assemblages throughout the ash-flow cannot be explained by crystal settling. The fractionation of the Joe Lott Tuff Member appears to closer fit the model of convection-driven thermogravitational diffusion.

  17. Phase-equilibrium geobarometers for silicic rocks based on rhyolite-MELTS—Part 3: Application to the Peach Spring Tuff (Arizona-California-Nevada, USA)

    NASA Astrophysics Data System (ADS)

    Pamukcu, Ayla S.; Gualda, Guilherme A. R.; Ghiorso, Mark S.; Miller, Calvin F.; McCracken, Reba G.

    2015-03-01

    Establishing the depths of magma accumulation is critical to understanding how magmas evolve and erupt, but developing methods to constrain these pressures is challenging. We apply the new rhyolite-MELTS phase-equilibria geobarometer—based on the equilibrium between melt, quartz, and two feldspars—to matrix glass compositions from Peach Spring Tuff (Arizona-California-Nevada, USA) high-silica rhyolite. We compare the results to those from amphibole geothermobarometry, projection of glass compositions onto the haplogranitic ternary, and glass SiO2 geobarometry. Quartz + 2 feldspar rhyolite-MELTS pressures span a relatively small range (185-230 MPa), consistent with nearly homogeneous crystal compositions, and are similar to estimates based on projection onto the haplogranitic ternary (250 ± 50 MPa) and on glass SiO2 (255-275 MPa). Amphibole geothermobarometry gives much wider pressure ranges (temperature-independent: ~65-300 MPa; temperature-dependent: ~75-295 MPa; amphibole-only: ~80-950 MPa); average Anderson and Smith (Am Mineral 80:549-559, 1995) + Blundy and Holland (Contrib Miner Petrol 104:208-224, 1990) or Holland and Blundy (Contrib Miner Petrol 116:433-447, 1994—Thermometer A, B) pressures are most similar to phase-equilibria results (~220, 210, 190 MPa, respectively). Crystallization temperatures determined previously with rhyolite-MELTS (742 °C), Zr-in-sphene (769 ± 20 °C), and zircon saturation (770-780 °C) geothermometry are similar, but temperatures from amphibole geothermometry (~450-955 °C) are notably different; the average Anderson and Smith + Holland and Blundy (1994—Thermometer B; ~710 °C) temperature is most consistent with previous estimates. The rhyolite-MELTS geobarometer effectively culls glass compositions affected by alteration or analytical issues; Peach Spring glass compositions that yield pressure estimates reveal a tight range of plausible Na2O and K2O contents, suggesting that low Na2O and high K2O contents of many Peach Spring samples are due to alteration. Use of altered whole-pumice compositions in rhyolite-MELTS simulations is likely the cause of the incorrect crystallization sequence reported previously for Peach Spring compositions. Using the rhyolite-MELTS geobarometer, we estimate a more realistic composition for Peach Spring Tuff high-silica rhyolite, and the calculated composition finds close matches with some analyzed rocks and results in the expected sequence of crystallization.

  18. Comparing MSL ChemCam Analyses to Shergottite and Terrestrial Rock Types

    NASA Astrophysics Data System (ADS)

    Bridges, J.; Edwards, P.; Dyar, M. D.; Fisk, M. R.; Schwenzer, S. P.; Forni, O.; Wiens, R. C.

    2014-12-01

    The ChemCam instrument on Mars Science Laboratory determines the elemental composition of target areas at ?6m range, and has acquired over 145000 spectra. Here we use the individual shots and averaged targets with the PLS1 dataset on both outcrops and float rocks. Various localities were sampled, including Rocknest, Sheepbed, Shaler, Cooperstown, Darwin and Kimberley. Rocknest and Sheepbed shots have quite homogeneous, basaltic compositions with Gini factors of 0.66 and 0.67 respectively (a Gini factor of 0 indicates a completely homogeneous dataset). Shaler is similarly homogeneous with a Gini factor 0.62 but is more felsic in composition. Darwin and Kimberley both follow a basaltic mixing trend between pyroxene and alkali feldspars. They have a heterogeneous spread with factors of 0.77 and 0.74. Kimberley and Darwin are the most alkaline outcrops, and then Shaler, finally Sheepbed and Rocknest are the least alkaline. The Na2O and K2O contents are controlled by variable abundances of alkaline feldspars. Many float rocks were also analysed. They include samples with mm-sized, visible feldspar grains, which are probable phenocrysts and cumulate grains. These rocks likely come from different sources as their compositions are quite heterogeneous e.g. the Gini factor for the whole set of feldspar-rich float rocks is 0.76 (using an average composition for each target). We compare these compositions with data from the MER APXS, and from this we can see that the float rocks sampled by MSL are closer to the alkaline feldspar end of the basaltic mixing trend than the more FeO+MgO-rich MER basalts (e.g. Rieder et al. 2004 10.1126/science.1104358) The basaltic shergottite meteorites also have higher FeO+MgO contents and lower Al2O3 than the MSL rocks. When compared on Al2O3-(FeOMgO)-(Na2OK2O)-CaO and other plots, the float rocks have compositions similar to a spread between terrestrial diorite and gabbro, though some have high Na2O+K2O contents.

  19. Effect of boron oxide addition on fibre drawing, mechanical properties and dissolution behaviour of phosphate-based glass fibres with fixed 40, 45 and 50?mol% P2O5.

    PubMed

    Sharmin, Nusrat; Parsons, Andrew J; Rudd, Chris D; Ahmed, Ifty

    2014-11-01

    Previous studies investigating manufacture of phosphate-based glass fibres from glasses fixed with P2O5 content less than 50?mol% showed that continuous manufacture without breakage was very difficult. In this study, nine phosphate-based glass formulations from the system P2O5-CaO-Na2O-MgO-B2O3 were prepared with P2O5 contents fixed at 40, 45 and 50?mol%, where Na2O was replaced by 5 and 10?mol% B2O3 and MgO and CaO were fixed to 24 and 16?mol%, respectively. The effect of B2O3 addition on the fibre drawing, fibre mechanical properties and dissolution behaviour was investigated. It was found that addition of 5 and 10?mol% B2O3 enabled successful drawing of continuous fibres from glasses with phosphate (P2O5) contents fixed at 40, 45 and 50?mol%. The mechanical properties of the fibres were found to significantly increase with increasing B2O3 content. The highest tensile strength (1200?±?130?MPa) was recorded for 45P2O5-16CaO-5Na2O-24MgO-10B2O3 glass fibres. The fibres were annealed, and a comparison of the mechanical properties and mode of degradation of annealed and non-annealed fibres were investigated. A decrease in tensile strength and an increase in tensile modulus were observed for the annealed fibres. An assessment of the change in mechanical properties of both the annealed and non-annealed fibres was performed in phosphate-buffered saline (PBS) at 37? for 28 and 60 days, respectively. Initial loss of mechanical properties due to annealing was found to be recovered with degradation. The B2O3-containing glass fibres were found to degrade at a much slower rate as compared to the non-B2O3-containing fibres. Both annealed and non-annealed fibres exhibited a peeling effect of the fibre's outer layer during degradation. PMID:24939962

  20. Geochemistry of Quaternary basaltic lavas from the Nuomin volcanic field, Inner Mongolia: Implications for the origin of potassic volcanic rocks in Northeastern China

    NASA Astrophysics Data System (ADS)

    Zhao, Yong-Wei; Fan, Qi-Cheng; Zou, Haibo; Li, Ni

    2014-05-01

    The Nuomin volcanic field (NM for short) in northern Greater Xing'An Mountains is dominated by Quaternary monogenetic eruptions, forming lava flows covering an area of about 600 km2. The lavas range from tephrite and basanite to trachybasalts, with high K2O contents between 2.6 wt.% and 4.3 wt.%, and K2O/Na2O between 0.78 and 1.08. These NM lavas are generally magnesian (Mg# between 0.59 and 0.78) and may contain useful information on the origin of potassic magmas in NE China. The NM lavas are characterized by relatively high (La/Yb)N (21.6-41.9) and enrichments in large ion lithophile elements (LILEs), but low in high field strength element (HSFE) concentrations. The NM lavas have negative ??d(- 0.8-- 3.0), 87Sr/86Sr between 0.704661 and 0.704880, 206Pb/204Pb between 17.0 and 17.2, 207Pb/204Pb between 15.41 and 15.43, and 208Pb/204Pb between 37.0 and 37.3. Their trace element spider diagram and chondrite-normalized rare earth element (REE) diagram are similar to those of Wudalianchi lavas, but are different from the Halaha-Chaoer river lavas in central Greater Xing'An Mountains. Their REE characteristics indicate that the NM lavas originate from garnet stability field. Based on petrological and geochemical data, we propose that the delamination of K-rich lithosphere mantle trigger the Quaternary potassic volcanism in Northeastern China.

  1. Some developments on ceramic-to-metal and glass-ceramics-to-metal seals and related studies

    NASA Astrophysics Data System (ADS)

    Kothiyal, G. P.; Goswami, M.; Shrikhande, V. K.

    2008-05-01

    Seals and coatings based on ceramics and glass-ceramics find numerous applications in different disciplines of science and technology including space, accelerators, nuclear energy, chemical industry. Ceramic-to-metal (CM) seals based on conventional design (using brazing alloys) and glass-ceramics have been prepared. While Ag-Cu brazing alloy has been used in conventional CM seal, we have employed lithium zinc silicate (LZS) and lithium aluminum silicate (LAS) glass-ceramics for glass-ceramics-to-metal (GCM) seals. LZS glass-ceramics based on two different compositions; (a) LZSL composition (wt.%)- Li2O: 12.65, ZnO: 1.85, SiO2: 74.4, Al2O3: 3.8, K2O: 2.95, P2O5: 3.15, and B2O3: 1.2 (low ZnO) and (b) LZSH composition (wt.%)- Li2O: 8.9, ZnO: 24.03, SiO2: 53.7, Na2O: 5.42, P2O5: 2.95, and B2O3: 5.0 (high ZnO) were prepared with desired sealing characteristics for matched type seals. In addition, (wt.%) 12.6Li2O-71.7SiO2-5.1Al2O3-4.9K2O-3.2B2O3-2.5P2O5 (LAS-GC) was investigated for compressive type of seal. LZS glass-ceramics-to-Cu as well as SS-321 seals were found to withstand a vacuum of 10-6 Torr with leak rate 10-9 Torr. 1/s and LAS GC-to-SS304 seal showed high pressure endurance of 12000psi. In order to understand the mechanism of sealing, glass-ceramics-to-metal interface study has also been carried out.

  2. Ft-Ir Spectroscopic Analysis of Potsherds Excavated from the First Settlement Layer of Kuriki Mound, Turkey

    NASA Astrophysics Data System (ADS)

    Bayazit, Murat; Isik, Iskender; Cereci, Sedat; Issi, Ali; Genc, Elif

    The region covering Southeastern Anatolia takes place in upper Mesopotamia, so it has numerous cultural heritages due to its witness to various social movements of different civilizations in ancient times. Kuruki Mound is located on the junction point of Tigris River and Batman Creek, near Oymatas village which is almost 15 km to Batman, Turkey. The mound is dated back to Late Chalcolithic. Archaeological excavations are carried out on two hills named as “Kuriki Mound-1” and “Kuriki Mound-2” in which 4-layer and 2-layer settlements have been revealed, respectively. This region will be left under the water by the reservoir lake of Il?su Dam when its construction is completed. Thus, characterization of ancient materials such as potsherds, metals and skeleton ruins should be rapidly done. In this study, 12 potsherds excavated from Layer-1 (the first settlement layer after the surface) in Kuriki Mound-2 were investigated by FT-IR spectrometry. Energy dispersive X-ray fluorescence (EDXRF) and X-ray diffraction (XRD) analyses were used as complementary techniques in order to expose chemical and mineralogical/phase contents, respectively. Obtained results showed that the potteries have been produced with calcareous clays and they include moderate amounts of MgO, K2O, Na2O and Fe2O3 in this context. Additionally, high temperature phases have also been detected with XRD analyses in some samples.

  3. Impact of Phase Separation on Waste Glass Durability

    SciTech Connect

    Jantzen, C.M.

    1999-11-29

    Phase separation in nuclear waste glasses has an adverse effect on glass durability. Phase separation in glasses generally takes the form of two immiscible glass phases which differ in chemical composition, density, and surface tension. Usually one phase is more soluble than the other. Phase separation complicates modeling of glass durability as a function of composition because the composition of the overall glass is known but the compositions of the two immiscible phases is not known: the performance of the overall glass is unpredictable and the long term durability of the glass can not be modeled. A discriminate analysis of 110 homogeneous and phase separated waste glasses allowed a ''phase separation discriminate function'' to be defined. The discriminate function is calculated based on glass oxide wt percent and compositionally differentiates between immiscible phases of different density. The discriminate function is defined in 14 component composition space although greater than 95 percent of the glass chemistry is dominated by seven major components (Na2O- K2O-Li2O-SiO2-Al2O3-B2O3-Fe2O3). The compositionally dependent discriminator function is used to eliminate phase separated glasses from being processed in the Savannah River Site (SRS) Defense Waste Processing Facility (DWPF). All glasses produced are homogeneous and thus have predictable long term durability.

  4. Impact of Phase Separation on Waste Glass Durability

    SciTech Connect

    Jantzen, C.M.

    1999-04-23

    Phase separation is shown to have an adverse and unpredictable effect on durability of borosilicate nuclear waste glasses. The glass chemistry and thermal history of the waste glass during solidification in a canister can impact the kinetics of phase separation and thus, the long term durability of a the glass. Although waste glasses contain 15-20 components, many of the components are present in minor amounts. Greater than 95 percent of the glass chemistry is dominated by the seven major components, Na2O- K2O-Li2O-SiO2-Al2O3-B2O3-Fe2O3. Although the phase equilibria of this seven component system has never been studied, a compositionally dependent "Phase Separation Discriminator" was developed from a database of 88 High Level Waste (HLW) glasses shown experimentally to be homogeneous and 22 shown experimentally to be phase separated. This discriminator ensures that the HLW glasses produced in the Defense Waste Processing Facility (DWPF) are homogeneous and have predictable long term durability.

  5. Early Cretaceous adakitic magmatism in the Dachagou area, northern Lhasa terrane, Tibet: Implications for slab roll-back and subsequent slab break-off of the lithosphere of the Bangong-Nujiang Ocean

    NASA Astrophysics Data System (ADS)

    Wu, Hao; Li, Cai; Xu, Mengjing; Li, Xingkui

    2015-01-01

    The late Mesozoic geodynamic evolution of the Lhasa terrane (Tibet) remains controversial due to a lack of systematic geochemical and chronological data. Here we present the results of geochemical and zircon U-Pb geochronological studies of two granodiorite plutons in the Dachagou area of the northern Lhasa terrane. The zircon U-Pb dating yielded magmatic crystallization ages of 104 and 117 Ma, indicating pluton emplacement in the Early Cretaceous. On the basis of their K2O contents, the granodiorites can be divided into low-K calc-alkaline granodiorites (LKG, 104 Ma) and high-K calc-alkaline granodiorites (HKG, 117 Ma), and both types are characterized by the adakitic signatures of high Na2O and Sr contents, low Yb and Y abundances, and high Sr/Y ratios. The fact that the LKG and HKG formed at different times and have different geochemical characteristics suggests different petrogenetic mechanisms. Specifically, the LKG were generated by the interaction of an oceanic-slab-derived melt with enriched mantle, while the HKG were derived via the partial melting of the lower crust followed by hybridization with a significant amount of sediment and a minor amount of mantle. Based on these data and the regional tectonic setting, we propose that the LKG and HKG resulted from different geodynamic mechanisms: the HKG were the product of slab roll-back, while the LKG resulted from the subsequent slab break-off during the southwards subduction of the Bangong-Nujiang Ocean seafloor.

  6. Interfaces in graded coatings on titanium-based implants

    PubMed Central

    Lopez-Esteban, S.; Gutierrez-Gonzalez, C. F.; Gremillard, L.; Saiz, E.; Tomsia, A. P.

    2013-01-01

    Graded bilayered glass-ceramic composite coatings on Ti6Al4V substrates were fabricated using an enameling technique. The layers consisted of a mixture of glasses in the CaO-MgO-Na2O-K2O-P2O5 system with different amounts of calcium phosphates (CPs). Optimum firing conditions have been determined for the fabrication of coatings having good adhesion to the metal, while avoiding deleterious reactions between the glass and the ceramic particles. The final coatings do not crack or delaminate. The use of high-silica layers (>60 wt % SiO2) in contact with the alloy promotes long-term stability of the coating; glass-metal adhesion is achieved through the formation of a nanostructured Ti5Si3 layer. A surface layer containing a mixture of a low-silica glass (~53 wt % SiO2) and synthetic hydroxyapatite particles promotes the precipitation of new apatite during tests in vitro. The in vitro behavior of the coatings in simulated body fluid depends both on the composition of the glass matrix and the CP particles, and is strongly affected by the coating design and the firing conditions. PMID:18384170

  7. Compliant alkali silicate sealing glass for solid oxide fuel cell applications: thermal cycle stability and chemical compatibility

    SciTech Connect

    Chou, Y. S.; Thomsen, Edwin C.; Williams, Riley T.; Choi, Jung-Pyung; Canfield, Nathan L.; Bonnett, Jeff F.; Stevenson, Jeffry W.; Shyam, Amit; Lara-Curzio, E.

    2011-03-01

    An alkali silicate glass (SCN-1) is currently being evaluated as a candidate sealing glass for solid oxide fuel (SOFC) applications. The glass containing ~17 mole% alkalis (K2O and Na2O) remains vitreous and compliant during SOFC operation, unlike conventional SOFC sealing glasses, which experience substantial devitrification after the sealing process. The non-crystallizing compliant sealing glass has lower glass transition and softening temperatures since the microstructure remains glassy without significant crystallite formation, and hence can relieve or reduce residual stresses and also has the potential for crack healing. Sealing approaches based on compliant glass will also need to satisfy all the mechanical, thermal, chemical, physical, and electrical requirements for SOFC applications, not only in bulk properties but also at sealing interfaces. In this first of a series of papers we will report the thermal cycle stability of the glass when sealed between two SOFC components, i.e., a NiO/YSZ anode supported YSZ bilayer and a coated ferritic stainless steel interconnect material. High temperature leak rates were monitored versus thermal cycles between 700-850oC using back pressures ranging from 0.2 psi to 1.0 psi. Isothermal stability was also evaluated in a dual environment consisting of flowing dilute H2 fuel versus ambient air. In addition, chemical compatibility at the alumina and YSZ interfaces was examined with scanning electron microscopy and energy dispersive spectroscopy. The results shed new light on the topic of SOFC glass seal development.

  8. The Geology of East Butte, a Rhyolitic Volcanic Dome on the Eastern Snake River Plain, Idaho

    NASA Technical Reports Server (NTRS)

    Bretches, J. E.; King, J. S.

    1985-01-01

    East Butte is a prominent volcanic dome located on the eastern Snake River Plain. It is situated 51 km west of Idaho Fallls in the southeast corner of the Idaho National Engineering facility. East Butte rises 350 meters above the Quaternary basalt flows which encircle its 2.4 kilometer diameter base. Its maximum elevation is 2003 meters above sea level. East Butte is composed dominantly of rhyolite. Armstrong and others (1975) determined a K-Ar age of 0.6 +/- m.y. for a rhyolite sample from East Butte. Detailed geologic mapping revealed East Butte to be a single, large cumulo-dome composed dominantly of rhyolite. Major element geochemical analyses indicate that the rhyolite of East Butte is mildly peralkaline (molecular excess of Na2O and K2O over Al2O3 and compositionally homogeneous. Color variations in the East Butte rhyolite result from varying amounts of chemical and physical weathering and to the degree of devitrification that the glass in the groundmass of the rhyolite underwent.

  9. Surface modifications of dental ceramic implants with different glass solder matrices: in vitro analyses with human primary osteoblasts and epithelial cells.

    PubMed

    Markhoff, Jana; Mick, Enrico; Mitrovic, Aurica; Pasold, Juliane; Wegner, Katharina; Bader, Rainer

    2014-01-01

    Ceramic materials show excellent esthetic behavior, along with an absence of hypersensitivity, making them a possible alternative implant material in dental surgery. However, their surface properties enable only limited osseointegration compared to titanium implants. Within this study, a novel surface coating technique for enhanced osseointegration was investigated biologically and mechanically. Specimens of tetragonal zirconia polycrystal (TZP) and aluminum toughened zirconia (ATZ) were modified with glass solder matrices in two configurations which mainly consisted of SiO2, Al2O3, K2O, and Na2O. The influence on human osteoblastic and epithelial cell viability was examined by means of a WST-1 assay as well as live/dead staining. A C1CP-ELISA was carried out to verify procollagen type I production. Uncoated/sandblasted ceramic specimens and sandblasted titanium surfaces were investigated as a reference. Furthermore, mechanical investigations of bilaterally coated pellets were conducted with respect to surface roughness and adhesive strength of the different coatings. These tests could demonstrate a mechanically stable implant coating with glass solder matrices. The coated ceramic specimens show enhanced osteoblastic and partly epithelial viability and matrix production compared to the titanium control. Hence, the new glass solder matrix coating could improve bone cell growth as a prerequisite for enhanced osseointegration of ceramic implants. PMID:25295270

  10. CdSe nanocrystals ingrained dielectric nanocomposites: synthesis and photoluminescence properties

    NASA Astrophysics Data System (ADS)

    Dey, Chirantan; Goswami, Madhumita; Karmakar, Basudeb

    2015-01-01

    Cadmium selenide (CdSe) nanocrystals ingrained dielectric nanocomposites in a B2O3–SiO2–Al2O3–Na2O–K2O borosilicate glass system were synthesized by a single step in situ melt quenching technique. The sizes of the nanocrystals as well as the band gap of the nanocomposites were controlled by both concentration of CdSe and post thermal treatment duration. The nanocomposites were characterized by different instrumental techniques including detailed photoluminescence studies. The sizes of the CdSe nanocrystals were found to alter in the range 4–16 nm as estimated from the effective mass approximation model and optical absorption spectroscopy. However, the TEM analysis revealed the generation of two different size ranges, 3–4 and 23–45 nm, of the particles within the dielectric matrix. Selected area diffraction (SAED) and x-ray diffraction (XRD) patterns authenticate the formation of hexagonal nanostructures of CdSe. These nanocomposites were found to be capable of exhibiting strong visible red luminescence around 715 nm on excitation at 446 nm. This has originated from the electron–hole recombination of CdSe nanocrystal and defects or traps related transitions. The properties of these nanocomposites advocate their significant applications as semiconductor based luminescent materials.

  11. A common volatilization trend in Transantarctic Mountain and Australasian microtektites: Implications for their formation model and parent crater location

    NASA Astrophysics Data System (ADS)

    Folco, L.; Glass, B. P.; D'Orazio, M.; Rochette, P.

    2010-04-01

    We studied the variations of the volatile major elements Na and K in Transantarctic Mountain microtektites and Australasian microtektites with distance from the putative source crater location in Indochina. The dataset includes 169 normal-type Australasian microtektites (101 from this study and 68 from the literature) from 24 deep-sea sediment cores up to 8000 km from Indochina, and 54 Transantarctic Mountain microtektites from northern Victoria Land, 11 000 km due southeast of Indochina. Normal-type (MgO < 5.5 wt.% and SiO 2 = 60-78 wt.%) Transantarctic Mountain microtektites and Australasian microtektites share a common volatilization trend with Na and K contents decreasing with distance from Indochina. The average total alkali (Na 2O + K 2O) concentrations at distance ranges of 1000-2000 km, 2000-4000 km, 4000-8000 km and > 8000 km are 4.27 ± 0.67 wt.% ( n = 84), 3.20 ± 1.21 wt.% ( n = 50), 2.10 ± 0.25 wt.% ( n = 35) and 1.25 ± 0.25 wt.% ( n = 54), respectively. The trend highlights a relationship between increasing loss of volatiles in microtektites with longer trajectories and higher temperature-time regimes which should be taken into account in microtektite formation modeling. The trend is consistent with a previous hypothesis that Transantarctic Mountain microtektites belong to the Australasian strewn field and that Indochina is the target region for the parent catastrophic impact.

  12. Multilevel Tunnelling Systems and Fractal Clustering in the Low-Temperature Mixed Alkali-Silicate Glasses

    PubMed Central

    2013-01-01

    The thermal and dielectric anomalies of window-type glasses at low temperatures (T < 1?K) are rather successfully explained by the two-level systems (2LS) standard tunneling model (STM). However, the magnetic effects discovered in the multisilicate glasses in recent times, magnetic effects in the organic glasses, and also some older data from mixed (SiO2)1?x(K2O)x and (SiO2)1?x(Na2O)x glasses indicate the need for a suitable extension of the 2LS-STM. We show that—not only for the magnetic effects, but also for the mixed glasses in the absence of a field—the right extension of the 2LS-STM is provided by the (anomalous) multilevel tunnelling systems (ATS) proposed by one of us for multicomponent amorphous solids. Though a secondary type of TS, different from the standard 2LS, was invoked long ago already, we clarify their physical origin and mathematical description and show that their contribution considerably improves the agreement with the experimental data. In spite of dealing with low-temperature properties, our work impinges on the structure and statistical physics of glasses at all temperatures. PMID:23861652

  13. Caractérisation et préconcentration granulométrique de la matière feldspathique d'Ain-Barbar, Algérie

    NASA Astrophysics Data System (ADS)

    Djouama, M. C.; Bounouala, M.; Ain-Souya, A.; Ghers, M.

    2005-05-01

    Les feldspaths sont répandus dans l'écorce terrestre mais seuls les feldspaths potassiques et sodiques sont très recherchés dans l'industrie céramique et verrière. Pour qu'ils soient utilisables, ces matériaux doivent contenir très peu d'impuretés nocives de fer et surtout de silice. La carrière d'Ain-Barbar exploite la matière feldspathique de teneurs moyennes respectives 74,5% SiO{2}, 9,5% 12,75% Al{2}O{3}, 1,30% Fe{2}O{3} et 9,5 K{2}O (0,90% Na{2}O). Toutefois, on constate un taux très élevé en quartz ce qui diminue la valeur du produit marchand et une teneur élevée en fer ce qui donne au produit fabriqué, des aspects de coloration le rendant impropre à la commercialisation. A cet effet, une caractérisation minéralogique et chimique a été réalisée sur une série d'échantillons prélevés du site d'extraction de la substance utile. Des essais de préconcentration granulométrique ont montré qu'un classement dimensionnel peut offrir une qualité de produits acceptables par les céramistes.

  14. Magneto-optic characteristics of ferric oxide quantum-dot-phosphate glass nanocomposite

    NASA Astrophysics Data System (ADS)

    Kumar, Ganapathy; Apte, Sanjay K.; Garaje, Sunil N.; Kulkarni, Milind V.; Mahajan, Satish M.; Kale, B. B.

    2010-03-01

    A phosphate-based glass was embedded with ferric oxide (Fe2O3) quantum dots in an effort to significantly enhance the magneto-optic properties of the glass. The phosphate glass was prepared with a composition 63P2O515.5K2O10ZnO6Na2O5.5BaO and doped with naked nanostructured Fe2O3 varying from 0.25 to 2%. The optical band gap of these glasses was observed to have reduced with an increasing in the concentration of Fe2O3. A maximum increase in Verdet constant of approximately 17 times that in a plain phosphate glass was observed at a wavelength of 632.8 nm, for an Fe2O3 doping concentration of 1% in the host glass. Preliminary measurements show that the resulting composite exhibits good enhancement in the Verdet constant and will have application in magneto-optical devices.

  15. Surface Modifications of Dental Ceramic Implants with Different Glass Solder Matrices: In Vitro Analyses with Human Primary Osteoblasts and Epithelial Cells

    PubMed Central

    Mick, Enrico

    2014-01-01

    Ceramic materials show excellent esthetic behavior, along with an absence of hypersensitivity, making them a possible alternative implant material in dental surgery. However, their surface properties enable only limited osseointegration compared to titanium implants. Within this study, a novel surface coating technique for enhanced osseointegration was investigated biologically and mechanically. Specimens of tetragonal zirconia polycrystal (TZP) and aluminum toughened zirconia (ATZ) were modified with glass solder matrices in two configurations which mainly consisted of SiO2, Al2O3, K2O, and Na2O. The influence on human osteoblastic and epithelial cell viability was examined by means of a WST-1 assay as well as live/dead staining. A C1CP-ELISA was carried out to verify procollagen type I production. Uncoated/sandblasted ceramic specimens and sandblasted titanium surfaces were investigated as a reference. Furthermore, mechanical investigations of bilaterally coated pellets were conducted with respect to surface roughness and adhesive strength of the different coatings. These tests could demonstrate a mechanically stable implant coating with glass solder matrices. The coated ceramic specimens show enhanced osteoblastic and partly epithelial viability and matrix production compared to the titanium control. Hence, the new glass solder matrix coating could improve bone cell growth as a prerequisite for enhanced osseointegration of ceramic implants. PMID:25295270

  16. Determination of the source rocks for the diatexites from the Edough Massif, Annaba, NE Algeria

    NASA Astrophysics Data System (ADS)

    Hadj Zobir, Soraya; Mocek, Beate

    2012-07-01

    The crystalline Edough Massif is located in the oriental part of the Algerian coastline. It consists of two tectonically superposed units of gneisses, augen-gneisses and migmatitic gneisses in the lower unit and micaschists in the upper unit. The crystalline rocks underwent a low to moderate degree of metamorphism; the gneisses suffered partial melting. They display migmatitic features such as nebulitic structures with contorted leucosome layers and K-feldspar porphyroblasts and thus can be classified as diatexites. The mineralogical composition of these rocks is very homogenous and consists of K-feldspar, micas and quartz. The feldspar-rich, arkosic nature of the outcrop implies a granitic source rock. High K2O/Na2O ratios and high A/CNK > 1.1 indicate an S-type granite source and a peraluminous composition of the protolith respectively. Chondrite normalized REE distribution patterns of the Edough diatexites show gently inclined patterns with a minor negative Eu anomaly (Eu/Eu* = 0.36-0.49), which points to a very slightly differentiated granitic source. The REE pattern and trace element data of the diatexites are similar to those of average Proterozoic upper continental crust, which suggests that they are derived mainly from upper continental crust and were deposited in continental margins.

  17. Geochemistry and petrogenesis of post-collisional ultrapotassic syenites and granites from southernmost Brazil: the Piquiri Syenite Massif.

    PubMed

    Nardi, Lauro V S; Plá-Cid, Jorge; Bitencourt, Maria de Fátima; Stabel, Larissa Z

    2008-06-01

    The Piquiri Syenite Massif, southernmost Brazil, is part of the post-collisional magmatism related to the Neoproterozoic Brasiliano-Pan-African Orogenic Cycle. The massif is about 12 km in diameter and is composed of syenites, granites, monzonitic rocks and lamprophyres. Diopside-phlogopite, diopside-biotite-augite-calcic-amphibole, are the main ferro-magnesian paragenesis in the syenitic rocks. Syenitic and granitic rocks are co-magmatic and related to an ultrapotassic, silica-saturated magmatism. Their trace element patterns indicate a probable mantle source modified by previous, subduction-related metasomatism. The ultrapotassic granites of this massif were produced by fractional crystallization of syenitic magmas, and may be considered as a particular group of hypersolvus and subsolvus A-type granites. Based upon textural, structural and geochemical data most of the syenitic rocks, particularly the fine-grained types, are considered as crystallized liquids, in spite of the abundance of cumulatic layers, schlieren, and compositional banding. Most of the studied samples are metaluminous, with K2O/Na2O ratios higher than 2. The ultrapotassic syenitic and lamprophyric rocks in the Piquiri massif are interpreted to have been produced from enriched mantle sources, OIB-type, like most of the post-collisional shoshonitic, sodic alkaline and high-K tholeiitic magmatism in southernmost Brazil. The source of the ultrapotassic and lamprophyric magmas is probably the same veined mantle, with abundant phlogopite + apatite + amphibole that reflects a previous subduction-related metasomatism. PMID:18506262

  18. Geochemical discrimination of five pleistocene Lava-Dam outburst-flood deposits, western Grand Canyon, Arizona

    USGS Publications Warehouse

    Fenton, C.R.; Poreda, R.J.; Nash, B.P.; Webb, R.H.; Cerling, T.E.

    2004-01-01

    Pleistocene basaltic lava dams and outburst-flood deposits in the western Grand Canyon, Arizona, have been correlated by means of cosmogenic 3He (3Hec) ages and concentrations of SiO2, Na2O, K2O, and rare earth elements. These data indicate that basalt clasts and vitroclasts in a given outburst-flood deposit came from a common source, a lava dam. With these data, it is possible to distinguish individual dam-flood events and improve our understanding of the interrelations of volcanism and river processes. At least five lava dams on the Colorado River failed catastrophically between 100 and 525 ka; subsequent outburst floods emplaced basalt-rich deposits preserved on benches as high as 200 m above the current river and up to 53 km downstream of dam sites. Chemical data also distinguishes individual lava flows that were collectively mapped in the past as large long-lasting dam complexes. These chemical data, in combination with age constraints, increase our ability to correlate lava dams and outburst-flood deposits and increase our understanding of the longevity of lava dams. Bases of correlated lava dams and flood deposits approximate the elevation of the ancestral river during each flood event. Water surface profiles are reconstructed and can be used in future hydraulic models to estimate the magnitude of these large-scale floods.

  19. Geological, petrogical and geochemical characteristics of granitoid rocks in Burma: with special reference to the associated W?Sn mineralization and their tectonic setting

    NASA Astrophysics Data System (ADS)

    Zaw, Khin

    The granitoid rocks in Burma extend over a distance of 1450 km from Putao, Kachin State in the north, through Mogok, Kyaukse, Yamethin and Pyinmana in the Mandalay Division, to Tavoy and Mergui areas, Tenasserim Division, in the south. The Burmese granitoids can be subdivided into three N-S trending, major belts viz. western granitoid belt, central graniotoid belt and eastern granitoid belt. The Upper Cretaceous-Lower Eocene western belt granitoids are characterized by high-level intrusions associated with porphyry Cu(Au) related, younger volcanics; these plutonic and volcanic rocks are thought to have been emplaced as a magmatic-volcanic arc (inner magmatic-volcanic arc) above an east-dipping, but westwardly migrating, subduction zone related to the prolonged plate convergence which occurred during Upper Mesozoic and Cenozoic. The central granitoid belt is characterized by mesozonal, Mostly Upper Cretaceous to Lower Eocene plutons associated with abundant pegmalites and aplites, numerous vein-type W-Sn deposits and rare co-magmatic volcanics. The country rocks are structurally deformed, metamorphic rocks of greenschist to upper amphibolite facies ranging in age as early as Upper Precambrian to Upper Paleozoic and locally of fossiliferous, metaclastic rocks (Mid Jurassic to Lower Cretaceous). Available K/Ar radiometric data indicate significant and possibly widespread thermal disturbances in the central granitoid belt during the Tertiary (mostly Miocence). In this study, the distribution, lithological, textural and structural characteristics of the central belt granitoids are reviewed, and their mineralogical, petrological, and geochemical features are presented. A brief description of W-Sn ore veins associated with these granitoid plutons is also reported. Present geological, petrological and geochemical evidences demonstrate that the W-Sn related, central belt granitoids are mostly granodiorite and granite which are commonly transformed into granitoid gneisses. These central belt granitoids were formed from a calc-alkaline magma derived from a source of continental, sialic materials. Highly potassiccharacters and high initial Sr 87/Sr 86 ratios (0.717±0.002) and Rb/Sr ratios (0.40-33.10) with an average value of 6.70, further corroborate their derivation from a well established continental, sialic basement. Although future chemical and isotopic investigations would be desirable, none of the present evidence argues the interpretation that the granitoid magma was generated by the re-melting of the regionally metamorphosed country rocks. The close association of W-Sn bearing quartz veins and the granitoid rocks also suggests that the metals were derived from the same crustal sources as their host granitoids. The central belt granitoids are considered to have been emplaced during the continent-arc collision of inferred Upper Triassic-Jurassic magmatic-volcanic arc with the continental foreland to the east at the early stage of westward migration of the east-dipping subduction zone to the west. The W-Sn related, central belt granitoids of Upper Mesozoic-Lower Eocene are notably different from those of mainly Triassic granitoids from northern Thailand and Permo-Triassic granites of the Malay Peninsula, and thus the central belt granitoids were emplaced in a uniquely distinct geologic and tetonic setting in the SE Asian region. Major element data for the central belt granitoids, which are associated with W-Sn mineralization lie within the field of Sn-mineralizing granites from New England in Na-K-Ca plot (Juniper and Kleeman, J. Geochem. Explor.11, 321-333, 1979), but largely outside the field on SiO 2?CaO +_MgO + FeO?Na 2O + K 2O + Al 2O 3 plot. Trace element abundances of the central belt granitoid rocks suggest that the Sn content of the granitoids alone should be used with great caution to discriminate the W-Sn bearing (mineralized) granitoid plutons from the W-Sn poor (barren) plutons in search for the W-Sn deposits in Burma, but trace element data show the tendency for granitoid plutons which bear W-Sn mi

  20. Martian alkaline basites chemically resemble basic rocks of the Lovozero alkaline massif, Kola peninsula

    NASA Astrophysics Data System (ADS)

    Kochemasov, G.

    The comparative wave planetology [1, 5] successfully overcomes the most principal martian test having now analyses of alkaline rocks from Columbia Hills [2, 3, 4]. This kind of rocks was predicted earlier on basis of the wave paradigm having stated that "the higher planetary relief range - the higher density difference between lithologies composing hypsometrically (tectonically) contrasting blocks [5]. This paradigm declares that "celestial bodies are dichotomic"(Theorem 1), "celestial bodies are sectoral" (Theorem 2), "celestial bodies are granular"(Theorem 3), "angular momenta of different level blocks tend to be equal" (Theorem 4)[1, 5]. Mars is a typical terrestrial planet but the farthest from Sun and thus with the smallest tide effects. Nevertheless it has the highest relief range and seems to be most distorted (ellipsoid in shape) and broken by deep fissures. The wave approach explains this by a warping action of standing waves of 4 ortho- and diagonal directions - they are the longest and highest in the martian case. These interfering warping waves caused by the elliptic keplerian orbits implying periodically changing accelerations and inertia-gravity forces produce inevitable tectonic dichotomy (the fundamental wave 1 long 2?R), sectoring (wave 2, ?R, and other overtones), granulation. A granule size depends on an orbital frequency: the higher frequency the smaller granule. The Earth's granule, as a scale, is ?R/4 (see it in NASA's PIA04159), Venus ` ?R/6, Mercury's ?R/16, Mars' ?R/2 (the sizes are strictly tied to orb. fr.). Along with the granule sizes increase relief ranges ( Mercury ˜5 km, Venus 14, Earth 20, Mars ˜30) and compositional (density) difference between lowland and highland lithologies [5]. The lowland compositions become Fericher and denser: enstatite (Mercury), Mg-basalt (Venus), tholeiite (Earth), Fe-basalt (Mars). The highland compositions get less dense, lighter: anorthosite, alkaline basalt, andesite and conditional "albitite" (syenite, granite) for Mars [5]. Actually the martian missions successively discovered andesite, dacite, low-Fe highlands. Now "Spirit" has found on a small outlier of highlands -Columbia Hills -a batch of thinly layered gently dipping light rocks that surely are not impact melts as at very short distance there is a sharp transition from light Fe-poor to ultrabasic rocks (on opposite slopes of this small hill) [6]. This layered sequence of more or less altered and weathered rocks resembles differentiated sequences of Lovozero and other alkaline and UB-alkaline massifs of Kola Peninsula (though fresh and much richer in alkalis). Here we compare compositions of alkaline basic rocks of Columbia Hills (dyke or sill [4]) with that of basic volcanics and a later dyke at Lovozero. 5 analyses in wt.%: 1-Backstay (tra1 chybasalt) & 2-Irvine (basalt) of CH, 3-augiteporphyrite, 4-essexite-porphyrite, 5- alkali- lamprophyre dyke of Lovozero. SiO2 -49.9, 47.7, 45.78, 48.09, 41.57; TiO2 - 0.93, 1.07, 7.80, 2.35, 2.92; Al2 O3 -13.2; 10.8, 8.08; 13.74; 11.77; Fe2 O3 -3.40, 7.79 (4.99), 5.90, 6.00, 4.53; FeO -10.6, 12.5 (15.0), 8.65, 7.60, 8.28; MnO -0.25, 0.37, 0.12, 0.17, 0.28; MgO -8.36, 10.8, 7.61, 7.19, 10.59; CaO -6.09, 6.12, 10.73, 8.77, 11.24; Na2 O -4.02, 2.72, 2.80, 2.84, 3.63; K2 O -1.02, 0.69, 1.97, 2.09, 1.38. Compositional similarities between basites occurring in alkaline conditions on both planets can be found. References: [1] Kochemasov G.G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., v. 1, # 3, 700; [2] Gellert R. et al. (2006) JGR Planets, v. 111, #E2, EO2505; [3] Squyres S.W. et al. (2006) JGR Planets, v.111, #E2, EO2511; [4] McSween H.Y. et al. (2006) JGR Planets, submitted ; [5] Kochemasov G. G. (1995) Golombek M.P., Edgett K.S., Rice J.W. Jr. (Eds). Mars Pathfinder Landing Site Workshop II: Characteristics of the Ares Vallis Region and Field trips to the Channeled Scabland, Washington. LPI Tech. Rpt. 95-01. Pt.1.LPI, Houston, 1995, 63 pp.; [6] Mittlefehldt D.W.

  1. Aqualite, a new mineral species of the eudialyte group from the Inagli alkaline pluton, Sakha-Yakutia, Russia, and the problem of oxonium in hydrated eudialytes

    NASA Astrophysics Data System (ADS)

    Khomyakov, A. P.; Nechelyustov, G. N.; Rastsvetaeva, R. K.

    2007-12-01

    Aqualite, a new eudialyte-group mineral from hydrothermally altered peralkaline pegmatites of the Inagli alkaline pluton (Sakha-Yakutia, Russia) is described in this paper. Natrolite, microcline, eckermanite, aegirine, batisite, innelite, lorezenite, thorite, and galena are associated minerals. Aqualite occurs as isometric crystals up to 3-cm across. The color is pale pink, with a white streak and vitreous luster. The mineral is transparent. The fracture is conchoidal. The mineral is brittle; no cleavage or parting is observed. The Mohs’ hardness is 4 to 5. The density is 2.58(2) g/cm3 (measured by the volumetric method) and 2.66 g/cm3 (calculated). Aqualite is optically uniaxial (+), ? = 1.569(1) and ? = 1.571(1). The mineral is pleochroic from colorless to pale pink on X and pink on Y, ? < ?. Aqualite is weakly fluorescent with a dull yellow color under ultraviolet light. The mineral is stable in 50% HCl and HNO3 at room temperature. Weight loss after ignition at 500°C is 9.8%. Aqualite is monoclinic, and the space group is R3. The unit-cell dimensions are a = 14.078(3) Å, c = 31.24(1) Å, V = 5362 Å3, and Z = 3. The strongest reflections in the X-ray powder pattern [ d, Å ( I)( hkl)] are: 4.39(100)(2005), 2.987(100)(315), 2.850(79)(404), 10.50(44)(003), 6.63(43)(104), 7.06(42)(110), 3.624(41)(027), and 11.43(39)(101). The chemical composition (electron microprobe, H2O determined with the Penfield method) is as follows (wt %): 2.91 Na2O, 1.93 K2O, 11.14 CaO, 1.75 SrO, 2.41 BaO, 0.56 FeO, 0.30 MnO, 0.17 La2O3, 0.54 Ce2O3, 0.36 Nd2O3, 0.34 Al2O3, 52.70 SiO2, 12.33 ZrO2, O.78 TiO2, 0.15 Nb2O5; 1.50 Cl, 9.93 H2O,-O=Cl2 0.34; where the total is 99.46. The empirical formula calculated on the basis of Si + Zr + Ti + Al + Nb = 29 apfu is as follows: [(H3O)7.94Na2.74K1.20Sr0.49Ba0.46Fe0.23Mn0.12]?13.18(Ca5.79REE0.19)?5.98 (Zr2.92Ti0.08)?3.0(Si25.57Ti0.21Al0.19Nb0.03)S26.0[O66.46(OH)5.54]?72.0 [(OH)2.77Cl1.23]?4.0. The simplified formula is (H3O)8(Na,K,Sr)5Ca6Zr3Si26O66(OH)9Cl. Aqualite differs from typical eudialyte by the extremely low contents of Na and Fe, with more than 50% Na being replaced with the (H3O)+ group. The presence of oxonium ions is confirmed by IR spectroscopic and X-ray single-crystal diffraction analysis. The mineral is compared with five structurally studied high-oxonium analogues from alkaline plutons of other regions. All of these minerals were formed at a relatively low temperature through the ion-exchange transformation of “protoeudialytes”; the successor minerals inherited the principal structural and compositional features of the precursor minerals. The name aqualite is derived from the Latin aqua in reference to its specific chemical composition. The type material of aqualite is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.

  2. Volcanic rocks of the Mendeleev Ridge (Arctic Ocean) - evidences for existence of the large igneous provinces within Arctic region: on the data of the High Arctic Russian Expedition "Arctic-2012"

    NASA Astrophysics Data System (ADS)

    Sergeev, Sergey; Petrov, Oleg; Morozov, Andrey; Kremenetsky, Alexander; Gusev, Evgeny; Shevchenko, Sergey; Krymsky, Robert; Belyatsky, Boris; Antonov, Anton; Rodionov, Nikolay

    2013-04-01

    During the complex geological-geophysical survey within August-October 2012 cruise of the Russian Expedition "Arctica-2012" on 9 sampling station (dredge, box-corer, drill-core) spaced on 450 km from the south to north alongside the Mendeleev Ridge were recovered more than 100 kg submarine volcanic rocks (which is represented about 10-15% of the total recovered bottom material), from calc-alkaline basalts, normal and subalkaline tholeites till andesite-dacites, typical lavas with glassy matrix and volcanic breccias, tuff-breccias and subvolcanic dolerites. We have studied 4 volcanic samples which are drill-cored (30-60 cm) of basement rocks at the depths of 2000-2500 m (79° and 83°N) or consolidate fragments of 30 kg weight collected at the steep escarpments with >45° slopes, three of them are tholeitic basalts (SiO2: 45.4-50.7, Al2O3: 13.7-21.7, MgO: 3.4-4.8, TiO2: 2.5-2.8, CaO: 4.7-11.4, Fe2O3: 5.9-14.4, Na2O: 2.9-3.8, K2O: 0.5-2.1 %), but the other one - is tuffobreccia with angular fragments of crystallized basalts and dolerites, and hydrated carbonatized (LOI up to 20%, ??2 - 35%) matrix. Isotopic and geochemical characteristics of the sample studied (low degree of REE fractionation: Cen/Ybn 1.6-2.2, moderate enrichment of HREE - 10-15×?1, low ratios of highly incompatible trace elements: Th/Ce = 0.03-0.04, Th/Nb = 0.14-0.16, Ce/Nb = 1.0-4.1) are very similar to those of high-Ti alkaline basalts of continental traps (CFB) connected with large mantle plume activities [Arndt et al., 1998; Hofmann, 1988] and close to the earlier discovered basalts from Chukcha borderland [Mukasa et al., 2009, 2012]. Measured Sr, Nd ? Pb isotope compositions of basalts vary from moderately enriched to moderately depleted compositions (143Nd/144Nd= 0.512706 - 0.512887, 87Sr/86Sr=0.704127-0.708580, 206Pb/204Pb=18.66-19.07, 207Pb/204Pb= 15.51-15.65, 208Pb/204Pb=38.42-39.20), reflecting different stages of secondary alterations, melt contamination by sedimentary material of host rocks and progressive magmas evolution during mixing of asthenospheric substances of the upwelling plume with the lithospheric component. Relatively high-radiogenic osmium isotope composition of the studied basalts (187Os/188Omeas=0.51525-1.07316) indicates the presence of significant share of the enriched lithospheric component in the source of basalt melts and the formation of this source at expense of relatively aged substances (model Re-Os ages from 600 to 1200 Ma). Age determination of the studied basalts effusions by argon-argon method is ongoing process but we have separated about 30 zircon grains mainly magmatic appearance (Th/U=0.6-2.0, long-prismatic grains without any visible signs of digestion and recrystallization, and overgrowths) from 4 samples and determined their U-Pb SHRIMP ages. Obtained age clusters indicate existence of old sialic basement underlying Mendeleev Ridge rocks (captured zircons with the ages of 2.7, 1.9, 1.6 and 0.8-1.2 Ga), which composition could be correlated with continental complexes of the Eurasia margins. At the same time, the finding of the volcanogenic zircons within the basalts with the ages of 127 and 260 Ma does not exclude the plausible existence on the studied territory of Polar Arctic of basalt effusions of two (or more) of igneous complexes corresponded with activities of mantle plumes - Cretaceous-Cenozoic (HALIP) and Triassic-Permian (resembling Siberian traps) ages

  3. The Origin of Garnet Megacrysts in Sulu UHP Clinopyroxenite, East China

    NASA Astrophysics Data System (ADS)

    Liou, J.; Zhang, R.; Tsujimori, T.; Li, T.; Chen, S.

    2003-12-01

    Abundant garnet megacrysts occur in one garnet clinopyroxenite layer from Rizhao of the Sulu UHP terrane, east China. The clinopyroxenite layers with various contents of garnet (trace to > 40%), ilmenite (< 5 %) and minor olivine form part of a strongly serpentinitzed peridotite body. Megacrystic Grt-bearing clinopyroxenite consists of variable amounts of megacrystic and porphyroblastic Grt, fine-grained matrix of Grt + Di + Ilm +/- Ol (Fo82-85), and secondary Amp, Chl and Spl. The megacrystic Grt with ellipsoidal and spherical shapes ranges from 2.5 to 12 cm, are coated with Chl + Amp +/- Cpx +/- Ep +/- Mt/Spl and develops distinct pressure shadow. Megacrystic Grt (Prp44-56Grs21-41Alm18-26) has similar compositions to porphyroblastic Grt (Prp40-43Grs37-40Alm20-21) but differs from matrix Grt (Prp25-32Grs46-56Alm18-22). At some interfaces between Grt and Cpx, Grt contains Ca-rich and Mg-poor compositions (Prp23-25Grs58-60Alm17-19). At least 6 types of inclusions occur: (a) trace spinel +/- magnetite lamellae, (b) trace dolomite, (c) trace amphibole (3.0-3.4 wt% Na2O; 0.3-0.4 wt% K2O; 0.4-0.5 wt% TiO2), (d) ilmenite with magnetite lamellae and rare spinel, (e) abundant coarse-grained Cpx (0.5-1.0 wt% Na2O) with characteristic exsolution lamellae of Amp (0.4-1.3 wt% Na2O; 0.7-1.0 wt% K2O; Mg# ˜0.9; 0.1-0.2 wt% TiO2) + Ilm +/- Grt described by Zhang and Liou (2003), and (f) composite phases of Cpx (e) + Ilm + Amp with ilmenite exsolution lamellae. The Grt megacrysts are fractured and veined with amphibolite facies assemblage Amp + Spl + Cpx +/- Pl and do not contain exsolved rutile needles. Available experimental data (4-15 GPa, 1000-1400\\deg C) of an Ilm-rich garnet clinopyroxenite composition indicate that Grt coexisting with Cpx contains considerable amount of TiO2 (> 1 wt%) only at P > 5 GPa; the results constrain the maximum depth for the formation of Grt megacryst. Parageneses and compositions of inclusion phases in megacrystic Grt and matrix minerals suggest the protolith of the megacrystic Grt-bearing clinopyroxenite probably was a high-Al clinopyroxenite formed at mantle wedge with an initial assemblage Cpx + Ilm + Spl +/- Ol +/- Dol at P < 3 GPa and T ˜1200\\deg C. Subsequent increase in P and decrease in T as the mantle fragment involved in a continental subduction zone, spinel reacted to form Grt whereas the Al-Ti bearing Cpx exsolved Amp + Grt + Ilm lamellae at subduction depths < 150 km. During exhumation and hydration, Grt coalesced to form megacrysts that engulfed relict lamellae-rich Cpx, Ilm, Spl, Amp and dolomite as inclusions. Porphyroblastic garnet formed subsequently and lamellae-rich Cpx recrystallized to matrix assemblage of Cpx + Grt + Ilm at ˜800\\deg C, ˜3 GPa. Deformation at crustal depths fractured megacrysts and amphibolite facies recrystallization occurred.

  4. Mineralogy and petrology of cretaceous subsurface lamproite sills, southeastern Kansas, USA

    USGS Publications Warehouse

    Cullers, R.L.; Dorais, M.J.; Berendsen, P.; Chaudhuri, Sambhudas

    1996-01-01

    Cores and cuttings of lamproite sills and host sedimentary country rocks in southeastern Kansas from up to 312 m depth were analyzed for major elements in whole rocks and minerals, certain trace elements in whole rocks (including the REE) and Sr isotopic composition of the whole rocks. The lamproites are ultrapotassic (K2O/Na2O = 2.0-19.9), alkalic [molecular (K2O/Na2O)/Al2O3 = 1.3-2.8], enriched in mantle-incompatible elements (light REE, Ba, Rb, Sr, Th, Hf, Ta) and have nearly homogeneous initial Sr isotopic compositions (0.707764-0.708114). These lamproites could have formed by variable degrees of partial melting of harzburgite country rock and cross-cutting veins composed of phlogopite, K-Ti richterite, titanite, diopside, K-Ti silicates, or K-Ba-phosphate under high H2O/CO2 ratios and reducing conditions. Variability in melting of veins and wall rock and variable composition of the metasomatized veins could explain the significantly different composition of the Kansas lamproites. Least squares fractionation models preclude the derivation of the Kansas lamproites by fractional crystallization from magmas similar in composition to higher silica phlogopite-sanidine lamproites some believe to be primary lamproite melts found elsewhere. In all but one case, least squares fractionation models also preclude the derivation of magmas similar in composition to any of the Kansas lamproites from one another. A magma similar in composition to the average composition of the higher SiO2 Ecco Ranch lamproite (237.5-247.5 m depth) could, however, have marginally crystallized about 12% richterite, 12% sanidine, 7% diopside and 6% phlogopite to produce the average composition of the Guess lamproite (305-312 m depth). Lamproite from the Ecco Ranch core is internally fractionated in K2O, Al2O3, Ba, MgO, Fe2O3, Co and Cr most likely by crystal accumulation-removal of ferromagnesian minerals and sanidine. In contrast, the Guess core (305-312 m depth) has little fractionation throughout most of the sill except in several narrow zones. Lamproite in the Guess core has large enrichments in TiO2, Ba, REE, Th, Ta and Sc and depletions in MgO, Cr, Co and Rb possibly concentrated in these narrow zones during the last dregs of crystallization of this magma. The Ecco Ranch sill did not show any evidence of loss of volatiles or soluble elements into the country rock. This contrasts to the previously studied, shallow Silver City lamproite which did apparently lose H2O-rich fluid to the country rock. Perhaps a greater confining pressure and lesser amount of H2O-rich fluid prevented it from escaping.

  5. Provenance and paleoweathering reconstruction of the Mesoproterozoic Hongshuizhuang Formation (1.4 Ga), northern North China

    NASA Astrophysics Data System (ADS)

    Luo, Qingyong; Zhong, Ningning; Wang, Yannian; Ma, Ling; Li, Min

    2015-03-01

    This is the first study presenting major and trace elemental data from the Mesoproterozoic Hongshuizhuang Formation shales in Yanshan basin, North China, in order to reconstruct its provenance and chemical weathering history. The shales are strongly depleted in Na2O and Sr and enriched in Y and transition metal elements relative to upper continental crust. Low Zr concentrations and various discriminant plots (e.g., Th/Sc-Zr/Sc and Al2O3-TiO2-Zr) indicate insignificant mineral sorting or recycling of these shales. The rocks show light rare earth element (REE) enrichment (La/YbCN = 3.99-6.92), flat heavy REE, and significantly negative Eu anomalies (Euan = 0.57-0.68) in chondrite-normalized REE patterns, similar to post-Archean Australian average shales. The fairly uniform REE patterns and trace element ratios indicate that the Hongshuizhuang Formation shales were derived from a felsic source area with granodiorite as the dominant contributor. Mixing calculations suggest a mixture of 30 % granite porphyry, 5 % basalt, and 65 % granodiorite as the possible source of the shales, also supporting that granodiorite was the predominant source. Intense chemical weathering of the source terrain is indicated by high values of the premetasomatized chemical index of alteration, plagioclase index of alteration, Rb/Sr, a strong positive correlation between TiO2 and Al2O3, depletion of CaO, Na2O, and Sr, and mineral compositions. Such strong chemical weathering suggests a warm and wet paleoclimate, perhaps due to high atmospheric CO2 and CH4 concentrations, and a near-equatorial location of the North China Craton in the Columbia supercontinent at 1.4 Ga.

  6. L.Cao and L.Fei-Fei.Spatially Coherent Latent Topic Model

    E-print Network

    Li, Fei-Fei

    amingo grand piano grandpiano joshua tree joshuatree kangaroo kangaroo laptop laptop lotus lotus schooner tree joshua tree joshua tree lotus lotus lotus Supervised recognition of 28 objects classes from

  7. An alise Matem atica III -Turma especial Fichas 1 a 5 -Solu c~ao parcial

    E-print Network

    Granja, Gustavo

    K #19;e limitado. 1 #12; Vamos agora ver que K #19;e fechado. Suponhamos que existe um ponto x que;e fechado. Suponhamos agora que K #19;e limitado e fechado. Come#24;camos por provar o resultado caso particular. Mostramos agora que dada uma cobertura aberta fU#11; g de K, existe #15; > 0 tal que

  8. Using CaO and MgO-rich industrial waste streams for carbon sequestration

    Microsoft Academic Search

    Joshuah K. Stolaroff; Gregory V. Lowry; David W. Keith

    2005-01-01

    To prevent rapid climate change, it will be necessary to reduce net anthropogenic CO2 emissions drastically. This likely will require imposition of a tax or tradable permit scheme that creates a subsidy for negative emissions. Here, we examine possible niche markets in the cement and steel industries where it is possible to generate a limited supply of negative emissions (carbon

  9. Generalising Incremental Knowledge Acquisition Paul Compton, Tri M. Cao and Julian Kerr

    E-print Network

    Compton, Paul

    A rule based system can be described a set of rules, an inference engine to enable the rules about the order of evaluation. This is certainly not the case in rule-based systems and is probably not true for any declarative programming. Rule-based systems include control mechanisms such as conflict

  10. Line Primitive Extraction by Interpretation of Line Continuation Ruini Cao, Chew Lim Tan

    E-print Network

    Tan, Chew Lim

    into more that one line primitive. Chen and Hsu presented an interpretive model of line continuation in [18-13] , circuit diagrams [14-15] , charts, and so on [16] . The extracted line primitives are further vectorized

  11. Relating theories of actions and reactive control Chitta Baral and Tran Cao Son

    E-print Network

    Baral, Chitta

    ' which says: `shooting causes the turkey to be dead if the gun is loaded'; and the effect of the action `load' which says: `loading the gun causes the gun to be loaded'. It should allow us to specify to reason and predict that if the turkey is initially alive and the gun is unloaded, then by loading the gun

  12. ADVANCED PROCESSING OF GaN FOR NOVEL ELECTRONIC DEVICES XIAN-AN CAO

    E-print Network

    Pearton, Stephen J.

    N Technology: A Late Blooming ................................................ .. 6 1.3 Processing Challenges Isolation and Doping ................................................ . 27 2.2 Rapid Thermal Processing #12;iv 4. HIGH RESISTANCE IMPLANT ISOLATION IN GaN .............................. .

  13. AN IMPLICIT ALGORITHM OF SOLVING NONLINEAR FILTERING FENG BAO , YANZHAO CAO , AND XIAOYING HAN

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    Cao, Yanzhao

    filtering problems are extended Kalman filter (EKF) [2, 8, 13, 14, 15] and particle filter method (PFM) [3, PFM provides a representation of the pdf. Since the seminal work of Gordon, Salmond and Smith [11], there have been significant development in both practical applications and theoretical analysis on PFM. Other

  14. Position-Verification in Multi-Channel Model Huajun Zhang, Zongyang Zhang and Zhenfu Cao

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    of wireless security [SSW03,CH05,SP05,VN06,CCS06,ZLFW06,CHH09]. Most previous protocols are insecure against is at position P, but in fact, no one is there. In [CHH09] and [CGMO09], from different points of view

  15. Steepest Descent Path Study of Electron-Transfer Reactions Jianshu Cao

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    Cao, Jianshu

    path of solvent polarization, thus providing a new perspective of electron- transfer reactions. Though of initial conditions: E b ) 0(, where is the friction coefficient and Eb is the transition state

  16. Caos, informazione e calore Dipartimento di Matematica e Istituto Nazionale di Fisica della Materia

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