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1

Thermal properties and FTIR spectra of K2O/Na2O iron borophosphate glasses  

NASA Astrophysics Data System (ADS)

Thermal properties and structure of iron borophosphate glasses containing Na2O and/or K2O have been investigated in this paper. A series of glasses of the general compositions xK2O(20-x)Na2O28.8Fe2O38B2O343.2P2O5, with x = 0, 5, 10, 15, 20 mol%, prepared by melt quenching method. The thermal stability and structure of as-prepared glasses was characterized by DTA and FTIR spectra, respectively. The results show that the thermal properties of sodium iron borophosphate glasses can be improved through the replacement of Na2O by appropriate quantity of K2O. FTIR data suggest that the substitution of K2O for Na2O in the 20Na2O28.8Fe2O38B2O343.2P2O5 glass does not produce fundamental changes in the structure of borophosphate network. But about 10 mol% K2O's substitution leads to a significant decrease of possible self-connection among boron-oxygen groups, which enhance the structure stability of sodium iron borophosphate glass, and thus the enhanced thermal stability were obtained.

Wang, Fu; Liao, Qilong; Xiang, Guanghua; Pan, Sheqi

2014-02-01

2

The effect of SiO2/Al2O3 ratio on the structure and microstructure of the glazes from SiO2-Al2O3-CaO-MgO-Na2O-K2O system  

NASA Astrophysics Data System (ADS)

Ceramic glazes are commonly used to covering of the facing surface of ceramics ware. A well-chosen oxide composition and firing conditions of glazes causes significant improvement of technical parameters of ceramic products. Modern glazes are classified as glass-ceramic composites with different crystalline phases arising during firing. The presence of crystals in the glass matrix is influenced by many factors, especially by oxides molar composition. A crucial role is played by the molar ratio of SiO2/Al2O3. In this work the six composition of glazes from SiO2-Al2O3-CaO-MgO-Na2O-K2O system were examined. The only variable is the ratio of the silicon oxideto alumina at a constant content of other components: MgO, CaO, K2O, Na2O, ZnO. In order to determine the real phase composition of the obtained glazes research on fluorescence spectrometer (XRF) were done. For structural studies X-ray diffraction (XRD) and spectroscopic in the middle infrared (MIR) were performed. In order to determine the state of the surface (microstructure) research on the scanning electron microscope (SEM) with EDX. The research allowed to determine the influence of SiO2/Al2O3 ratio on the structure and phase composition of glazes and the nature, and type of formed crystalline phases.

Partyka, Janusz; Sitarz, Maciej; Le?niak, Magdalena; Gasek, Katarzyna; Jele?, Piotr

2015-01-01

3

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

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

4

Iron-Enrichment or Secondary Garnet Pyroxenite: Evidence from CaO- K2O-RICH HSDP2 Mauna Kea Glasses, Hawaii  

NASA Astrophysics Data System (ADS)

Precise mass-spectrometric analyses of the Fe/Mn ratio in mantle-derived magmas reveal that Hawaiian shield magmas in general have higher Fe/Mn (>65) than MORB (52-57) and Icelandic magmas (<60). Under the assumption that the source of Hawaiian shield magmas is peridotite-dominated, Humayun et al. (2004) interpreted the high Fe/Mn in Hawaiian magmas as a result of excess iron in the source, attributed to core-mantle interaction. However, based on the high SiO2 content in Hawaiian magmas and the high Ni content in Hawaiian olivines, Sobolev et al. (2005; 2007) argued that an olivine-free, pyroxenitic source contributes these geochemical features of Hawaiian magmas. Additionally, the pyroxenitic source model might account for the elevated Fe/Mn of Hawaiian magmas because compared to Mn, Fe is more compatible in olivine and less compatible in pyroxenes and garnet, and consequently, partial melts of olivine-free garnet pyroxenite can have high Fe/Mn relative to the bulk source. These two rather different views of the origin of the sources of Hawaiian magmas (and their distinctive Fe/Mn ratios) have important geodynamic implications for the Hawaiian plume relating to either the depth of origin at the core-mantle boundary, or to the amount of recycled crust in the source. These contrasting models (i.e., an Fe-enriched peridotitic source vs. an olivine-deficient source produced via dacite interacting with a non-Fe-enriched peridotite) can be tested by comparing magmas produced by partial melting of peridotite with those produced by partial melting of pyroxenite. For example, a specific prediction of the dominantly pyroxenitic source model is that Hawaiian magmas generated by melting of peridotite should have Fe/Mn<60, similar to MORB and Icelandic magmas. In this study, we focus on a small group of Mauna Kea volcanic glasses, characterized by low SiO2 contents and high CaO and K2O contents, recovered from the Hawaiian Scientific Drilling Project Phase 2 (HSDP2) drill core (Stolper et al., 2004). Herzberg (2006) has argued that the high CaO contents of these glasses are strong evidence of a peridotitic source and while some other Hawaiian magmas (e.g., alkalic magmas from Loihi) are also generally accepted to have dominantly peridotitic source, a focus on the distinctive HSDP2 CaO- K2O-rich glasses provides a clean test of whether Hawaiian peridotitic source have elevated Fe/Mn ratios like other Hawaiian magmas, or more MORB-like ratios as predicted by Sobolev et al. (2005; 2007). We report precise mass-spectrometric Fe/Mn ratios and transition metal abundances determined in situ by laser ablation ICP-MS on a suite of seven HSDP2 CaO-K2O-rich volcanic glasses. Six of the seven glasses have Sc>38 ppm, higher than any previously published Hawaiian shield lavas (<34 ppm), and they plot well within the MORB field. Since Sc is compatible in garnet and clinopyroxene, the high Sc abundances in HSDP2 CaO-K2O-rich glasses are consistent with their peridotitic origin proposed by Herzberg (2006). These HSDP2 CaO-K2O-rich glasses have Fe/Mn>63, and plot at the low-MgO end of the olivine control trend defined by Hawaiian lavas. Therefore, provided the CaO-K2O-rich glasses are derived from a peridotitic source as concluded by Herzberg (2006), we conclude that the high Fe/Mn in Hawaiian lavas is not a reflection of partial melting of an olivine-deficient source but, rather, it reflects an iron enrichment in the lavas' source, the Hawaiian plume, which may originate from core-mantle interaction.

Huang, S.; Humayun, M.; Baker, M. B.; Stolper, E.

2008-12-01

5

Experimental investigation of the effects of K2O on the composition of near-solidus partial melts of peridotite at 3 GPa  

NASA Astrophysics Data System (ADS)

K2O is highly mobile in fluids and silicate melts that may act as metasomatic agents in the upper mantle. Enrichment in K2O depresses the solidus of peridotite (Hirschmann, 2000) and, at low pressures, increases SiO2 and lowers CaO concentrations of near-solidus partial melts (Hirschmann et al., 1998). High SiO2 and low CaO characteristic of EM-type OIB (e.g., Jackson and Dasgupta, 2008) may be related to enrichment of their sources in K2O; however, primary OIB are likely generated beneath oceanic lithosphere at pressures (~3 GPa) where the effects of K2O on melt compositions is not well-constrained. We present the results of piston cylinder experiments at 3 GPa that investigate the effects of variable K2O concentrations on compositions of near-solidus partial melts of peridotite. K2O was added to an alkali picrite multiply-saturated in a garnet lherzolite residue with a bulk composition similar to fertile lherzolite KLB-1. Experiments were performed with initial K2O in the melt of 2 wt.% and 4 wt.% at temperatures from 1430-1450 °C, near the solidus of KLB-1 analogs (1445±15 °C). Differences in experimental melt fraction resulted in quenched melts each with a different K2O concentration between 2.5-4.6 wt.%. Variable experimental melt fraction led to several other systematic compositional variations in the melt, such as increased TiO2 and decreased Mg# at low experimental melt fractions. To account for these differences, melt compositions were corrected for melt fraction effects to a common TiO2 content. Corrected melt compositions are representative of near-solidus partial melts of a single garnet peridotite source with varying initial K2O concentrations. The strongest effects of increased K2O in the melt are increased SiO2 and decreased CaO. For each 1 wt.% increase in K2O in the melt SiO2 increases and CaO decreases ~0.5 wt.%. This is a stronger effect than anticipated by (Hirschmann et al., 1998) for melts at 3 GPa. Al2O3 was also found to increase with K2O, and Na2O and Cr2O3 both decrease. Increased K2O moves the SiO2 and CaO concentrations of near-solidus partial melts of peridotite toward those of EM1 and EM2-type OIB, but the amount of K2O required to reach those concentrations is greater (4-5 wt.%) than is found in typical EM-type OIB (1-2 wt.%), and increased Al2O3 associated with high K2O moves partial melts of peridotite away from typical OIB compositions. A source that has a high modal proportion of clinopyroxene may be required in conjunction with high K2O concentrations to produce the low CaO contents of extreme EM-type OIB (CaO < 8 wt.%).

Davis, F. A.; Hirschmann, M. M.

2012-12-01

6

Sol-Gel Synthesis and Electrospraying of Biodegradable (P2O5)55-(CaO)30-(Na2O)15 Glass Nanospheres as a Transient Contrast Agent for Ultrasound Stem Cell Imaging.  

PubMed

Ultrasound imaging is a powerful tool in medicine because of the millisecond temporal resolution and submillimeter spatial resolution of acoustic imaging. However, the current generation of acoustic contrast agents is primarily limited to vascular targets due to their large size. Nanosize particles have the potential to be used as a contrast agent for ultrasound molecular imaging. Silica-based nanoparticles have shown promise here; however, their slow degradation rate may limit their applications as a contrast agent. Phosphate-based glasses are an attractive alternative with controllable degradation rate and easily metabolized degradation components in the body. In this study, biodegradable P2O5-CaO-Na2O phosphate-based glass nanospheres (PGNs) were synthesized and characterized as contrast agents for ultrasound imaging. The structure of the PGNs was characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), (31)P magic angle spinning nuclear magnetic resonance ((31)P MAS NMR), and Fourier transform infrared (FTIR) spectroscopy. The SEM images indicated a spherical shape with a diameter size range of 200-500 nm. The XRD, (31)P NMR, and FTIR results revealed the amorphous and glassy nature of PGNs that consisted of mainly Q(1) and Q(2) phosphate units. We used this contrast to label mesenchymal stem cells and determined in vitro and in vivo detection limits of 5 and 9 ?g/mL, respectively. Cell counts down to 4000 could be measured with ultrasound imaging with no cytoxicity at doses needed for imaging. Importantly, ion-release studies confirmed these PGNs biodegrade into aqueous media with degradation products that can be easily metabolized in the body. PMID:25625373

Foroutan, Farzad; Jokerst, Jesse V; Gambhir, Sanjiv S; Vermesh, Ophir; Kim, Hae-Won; Knowles, Jonathan C

2015-02-24

7

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

E-print Network

fluorine-bearing granitic and rhyolitic magmas. Topaz and cryolite are stable saturating solid phases, and haplogranite^topaz^H2O at 6408C and $2 wt % F. Topaz and cryolite form a binary peralkaline eutectic at 6608C of multiphase eutectics with quartz and alkali feldspar towards the topaz^cryolite join and enables the silicate

Long, Bernard

8

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

E-print Network

^silicate liquid immiscibility spans the silica^albite^cryolite and silica^topaz^cryolite ternaries/Na ¼ 0Á75. The addition of topaz, however, significantly lowers melting temperatures and allows strong fluorine enrichment in subaluminous compositions. At 100 MPa, the binary topaz^cryolite eutectic is located

Long, Bernard

9

Effects of sodium and potassium ions on a novel SeO2-B2O3-SiO2-P2O5-CaO bioactive system  

NASA Astrophysics Data System (ADS)

The study is focused on Na2O and/or K2O influence on a new sol-gel derived SeO2-B2O3-SiO2-P2O5-CaO bioactive system. The structural changes induced by Na2O and/or K2O addition were correlated with the samples behavior in simulated biological media. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were used to characterize the structure and the type of the chemical bonds. The morphology of the samples was characterized through scanning electron microscopy (SEM). XRD results pointed out a prevalent vitreous structure with an incipient hydroxyapatite (HA) crystalline phase. FTIR results revealed a complex network consisting of silicate, phosphate and borate units, as well as the development of both A- and B-type of carbonate-substituted HA. The bioactivity of the samples was tested in vitro following the evolution of the apatite layers self-assembled on the samples surface in simulated body fluid. Their biocompatibility was investigated after samples surface functionalization with protein. The results indicate that sodium and potassium addition improves the biocompatibility by enhancement of protein adherence on samples surface and without to prevent the samples bioactivity.

Trandafir, D. L.; Ponta, O.; Ciceo-Lucacel, R.; Simon, V.

2015-01-01

10

Thermodynamics of the Na2O-P2O5 system  

NASA Astrophysics Data System (ADS)

The activity of Na2O in the melts of the Na2O-P2O5 system has been determined using a high temperature electrochemical cell with a Na2O-WO3 melt at the reference electrode and fused silica as the solid electrolyte as shown below. _{Na_2 O - WO_3 melt}^{Pt(s),O_2 (g)} left| {_{fused silica}^{ Na^ + } } right|_{Na_2 O - P_2 O_5 melt}^{O_2 (g), Pt(s)} The thermodynamics of the Na2O-P2O5 binary system in the composition range of 50 to 75 mole pet Na2O has been studied. The activities of Na2O and P2O5 in the melt have been carefully analyzed. The free energy of four sodium phosphates has been evaluated with the help of the phase diagram of this system. Based on this study, a solid-state phase transformation for the 3Na2O·P2O5 compound has been suggested at a temperature below 1217 K. The entropy of the transformation is near zero. The enthalpy of transformation is estimated to be 101.51 kJ/mole 3Na2O·P2O5.

Huang, Chu T.; Lin, Ray Y.

1989-04-01

11

Structure, dielectric and bioactivity of P2O5-CaO-Na2O-B2O3 bioactive glass  

NASA Astrophysics Data System (ADS)

Bioactive phosphate glasses have been widely investigated for bone repair. Phosphate glass system of 47P2O5-30.5CaO-(22.5-x)Na2O-xB2O3 has been prepared by melt quenching technique. From the Raman analysis, it is confirmed that phosphate network form metaphosphate structure. Bioactivity of the glass is studied by immersing the prepared glass in simulated body fluid (SBF). All the glasses exhibited bioactivity after soaking in SBF. Addition of B2O3 to the glass by replacing the Na2O produces considerable effect on the dielectric and bioactivity of the glass. Ion dynamics are also analyzed through imaginary modulus and imaginary dielectric permittivity.

Maheswaran, A.; Hirankumar, G.; Heller, Nithya; Karthickprabhu, S.; Kawamura, Junichi

2014-06-01

12

Flower-like Na2O nanotip synthesis via femtosecond laser ablation of glass  

PubMed Central

The current state-of-the-art in nanotip synthesis relies on techniques that utilize elaborate precursor chemicals, catalysts, or vacuum conditions, and any combination thereof. To realize their ultimate potential, synthesized nanotips require simpler fabrication techniques that allow for control over their final nano-morphology. We present a unique, dry, catalyst-free, and ambient condition method for creating densely clustered, flower-like, sodium oxide (Na2O) nanotips with controllable tip widths. Femtosecond laser ablation of a soda-lime glass substrate at a megahertz repetition rate, with nitrogen flow, was employed to generate nanotips with base and head widths as small as 100 and 20?nm respectively, and lengths as long as 10??m. Control of the nanotip widths was demonstrated via laser dwell time with longer dwell times producing denser clusters of thinner nanotips. Energy dispersive X-ray analysis reveals that nanotip composition is Na2O. A new formation mechanism is proposed, involving an electrostatic effect between ionized nitrogen and polar Na2O. The synthesized nanotips may potentially be used in antibacterial and hydrogen storage applications. PMID:22809176

2012-01-01

13

Unveiling the charge migration mechanism in Na2O2: implications for sodium-air batteries.  

PubMed

Metal-air batteries have become promising candidates for modern energy storage due to their high theoretical energy density in comparison to other storage devices. The lower overpotential of Na compared with Li makes Na-air batteries more efficient in terms of battery lifetime. Additionally, the abundance of Na over Li is another advantage for Na batteries compared to Li batteries. Na2O2 is one of the main products of sodium-air battery reactions. The efficiency of air cells is always related to the charge transport mechanisms in the formed product. To unveil these diffusion mechanisms in one of the main products of the cell reaction Na-O2 we systematically investigate the mobility of charge carriers as well as the electronic structural properties of sodium peroxide. The framework of the density functional theory based on hybrid functional approach is used to study the mobility of charge carriers and intrinsic defects in Na2O2. Our calculations reveal that the formation of small electron and hole polarons is preferentially occurring over the delocalized state in the crystal structure of Na2O2. The migration of these small polarons displays activation energies of about 0.92 eV and 0.32 eV for the electron and hole polarons respectively, while the analysis of the charged sodium vacancy mobility reveals an activation energy of about 0.5 eV. These results suggest that the charge transport in sodium peroxide would mainly occur through the diffusion of hole polarons. PMID:25732774

Araujo, Rafael B; Chakraborty, Sudip; Ahuja, Rajeev

2015-03-11

14

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

PubMed

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

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

2012-02-01

15

Compositional and microstructural design of highly bioactive P2O5-Na2O-CaO-SiO2 glass-ceramics.  

PubMed

Bioactive glasses having chemical compositions between 1Na(2)O-2CaO-3SiO(2) (1N2C3S) and 1.5Na(2)O-1.5CaO-3SiO(2) (1N1C2S) containing 0, 4 and 6 wt.% P(2)O(5) were crystallized through two stage thermal treatments. By carefully controlling these treatments we separately studied the effects on the mechanical properties of two important microstructural features not studied before, crystallized volume fraction and crystal size. Fracture strength, elastic modulus and indentation fracture toughness were measured as a function of crystallized volume fraction for a constant crystal size. Glass-ceramics with a crystalline volume fraction between 34% and 60% exhibited a three-fold improvement in fracture strength and an increase of 40% in indentation fracture toughness compared with the parent glass. For the optimal crystalline concentration (34% and 60%) these mechanical properties were then measured for different grain sizes, from 5 to 21 ?m. The glass-ceramic with the highest fracture strength and indentation fracture toughness was that with 34% crystallized volume fracture and 13 ?m crystals. Compared with the parent glass, the average fracture strength of this glass-ceramic was increased from 80 to 210 MPa, and the fracture toughness from 0.60 to 0.95 MPa.m(1/2). The increase in indentation fracture toughness was analyzed using different theoretical models, which demonstrated that it is due to crack deflection. Fortunately, the elastic modulus E increased only slightly; from 60 to 70 GPa (the elastic modulus of biomaterials should be as close as possible to that of cortical bone). In summary, the flexural strength of our best material (215 MPa) is significantly greater than that of cortical bone and comparable with that of apatite-wollastonite (A/W) bioglass ceramics, with the advantage that it shows a much lower elastic modulus. These results thus provide a relevant guide for the design of bioactive glass-ceramics with improved microstructure. PMID:22032913

Peitl, Oscar; Zanotto, Edgar D; Serbena, Francisco C; Hench, Larry L

2012-01-01

16

Thermal and elastic characterization of Sb2O3-Na2O-ZnO glasses  

NASA Astrophysics Data System (ADS)

New glasses were investigated in the ternary system Sb2O3-Na2O-ZnO. The glass transition temperature, Tg, and the onset of the crystallization Tx range from 278 to 304 °C and from 370 to 450 °C, respectively. The thermal stability factor (Tx-Tg) lies between 109 and 155 °C. Ultrasonic velocities were measured by using the pulse echo method to determine the elastic parameters (E, G, K and L) and other related parameters (Poisson's ratio, acoustic impedance and Debye temperature). Other physical properties were also measured, such as density and microhardness. The different measured properties are analyzed in the light of the structural role of ZnO in these glasses.

Hamzaoui, M.; Azri, S.; Soltani, M. T.; Lebullenger, R.; Poulain, M.

2013-11-01

17

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

NASA Astrophysics Data System (ADS)

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.

Safarian, Jafar; Tranell, Gabriella; Tangstad, Merete

2015-03-01

18

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

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

19

Evaluation of CaO-SiO2-P2O5-Na2O-Fe2O3 bioglass-ceramics for hyperthermia application.  

PubMed

Magnetic bioglass ceramics (MBC) are being considered for use as thermoseeds in hyperthermia treatment of cancer. While the bioactivity in MBCs is attributed to the formation of the bone minerals such as crystalline apatite, wollastonite, etc. in a physiological environment, the magnetic property arises from the magnetite [Fe3O4] present in these implant materials. A new set of bioglasses with compositions 41CaO x (52-x)SiO2 x 4P2O5 x xFe2O3 x 3Na2O (2 < or = x < or = 10 mol% Fe2O3) have been prepared by melt quenching method. The as-quenched glasses were then heat treated at 1050 degrees C for 3 h to obtain the glass-ceramics. The structure and microstructure of the samples were characterized using X-ray diffraction and microscopy techniques. X-ray diffraction data revealed the presence of magnetite in the heat treated samples with x > or = 2 mol% Fe2O3. Room temperature magnetic property of the heat treated samples was investigated using a Vibrating Sample Magnetometer. Field scans up to 20 kOe revealed that the glass ceramic samples had a high saturation magnetization and low coercivity. Room temperature hysteresis cycles were also recorded at 500 Oe to ascertain the magnetic properties at clinically amenable field strengths. The area under the magnetic hysteresis loop is a measure of the heat generated by the MBC. The coercivity of the samples is another important factor for hyperthermia applications. The area under the loop increases with an increase in Fe2O3 molar concentration and the. coercivity decreases with an increase in Fe2O3 molar concentration The evolution of magnetic properties in these MBCs as a function of Fe2O3 molar concentration is discussed and correlated with the amount of magnetite present in them. PMID:18560766

Singh, Rajendra Kumar; Srinivasan, A; Kothiyal, G P

2009-12-01

20

Antibacterial and bioactive silver-containing Na 2 O·CaO·2SiO 2 glass prepared by sol–gel method  

Microsoft Academic Search

The antibacterial effect of addition of silver oxide to Na2O·CaO·2SiO2 glass have been studied. Silver containing and silver free Na2O·CaO·2SiO2 glasses have been prepared by sol–gel synthesis using tetramethil orthosilicate, sodium ethoxide, calcium nitrate tetrahydrate and silver nitrate as starting materials and methyl ethyl ketone as solvent. The gel was examined by differential thermal analysis, thermo gravimetric analysis, FTIR spectroscopy

M. Catauro; M. G. Raucci; F. de Gaetano; A. Marotta

2004-01-01

21

Optical band gap studies on (55- x)Na 2O- xPbO-45P 2O 5 (SLP) glass system  

NASA Astrophysics Data System (ADS)

Sodium lead phosphate (SLP) glasses in the series (55- x)Na 2O- xPbO-45P 2O 5 with x varying from 55 to 0 were prepared by the single step melt quenching process with Na2CO3 ( sodium carbonate ), PbO (lead monoxide) and NH 4H 2PO 4 (ammonium dihydrogen phosphate - ADP) as starting materials. The 12 samples prepared were grouped into two batches with batch A having 55? x?30 for increasing Na 2O and batch B having 0? x?25 for increasing PbO to understand the roles of Na 2O and PbO in phosphate network. The optical absorption spectra of these glasses were recorded in the range 240-300 nm. The fundamental optical absorption edges were observed for all glasses except for Na 2O-P 2O 5 glass with x=0. From these absorption edge studies the optical band gap ( Eopt) and the Urbach energy ( ?E) values have been evaluated by following the available semi-empirical theories. The Eopt values were found to vary from 4.33 to 4.49 eV for batch A with increasing Na 2O content and from 4.55 to 4.40 eV for batch B with increasing PbO content. The Eopt behavior with increasing Na 2O was found to be complementary to increasing PbO in the glass network. The role of Na 2O is found to increase the Eopt value by causing decrease in the number of bridging oxygens affected.

Subrahmanyam, K.; Salagram, M.

2000-12-01

22

Physical and optical studies on Li2O-Na2O-WO3-B2O3 glasses  

NASA Astrophysics Data System (ADS)

Glasses with composition xLi2O-(30-x)Na2O-10WO3-60B2O3 (where x=0, 5, 10, 15, 20, 25 and 30 mol%) have been prepared using the melt quenching technique. In the present work, the mixed alkali effect (MAE) has been investigated in the above glass system through density and optical studies. The density of the present gasses varies non-linearly, the exhibiting the mixed alkali effect. From the optical absorption studies, the values of direct optical band gap, indirect optical band gap energy (Eo) and Urbach energy(?E) have been evaluated. The values of E0 and ?E vary non-linearly with composition parameter, showing the mixed alkali effect.

Edukondalu, Avula; Kavitha, B.; Hameed, Abdul; Siva Kumar, K.

2015-02-01

23

Understanding the magnetic behavior of heat treated CaO-P2O5-Na2O-Fe2O3-SiO2 bioactive glass using electron paramagnetic resonance studies  

NASA Astrophysics Data System (ADS)

Bioactive glass of composition 41CaO-44SiO2-4P2O5-8Fe2O3-3Na2O has been heat treated in the temperature (TA) range of 750-1150 °C for time periods (tA) ranging from 1 h to 3 h to yield magnetic bioactive glass ceramics (MBCs). X-ray diffraction studies indicate the presence of bone mineral (hydroxyapatite and wollastonite) and magnetic (magnetite and ?-hematite) phases in nanocrystalline form in the MBCs. Electron paramagnetic resonance (EPR) study was carried out to understand the variation in saturation magnetization and coercivity of the MBCs with TA and tA. These studies reveal the nature and amount of iron ions present in the MBCs and their interaction in the glassy oxide matrix as a function of annealing parameters. The deterioration in the magnetic properties of the glass heat treated above 1050 °C is attributed to the crystallization of the non-magnetic ?-hematite phase. These results are expected to be useful in the application of these MBCs as thermoseeds in hyperthermia treatment of cancer.

Shankhwar, Nisha; Kothiyal, G. P.; Srinivasan, A.

2014-09-01

24

Kinetics of Na2O and B2O3 Loss From CaO-SiO2-Al2O3 Slags  

NASA Astrophysics Data System (ADS)

The present work was carried out to study the loss of Na2O and B2O3 from CaO-SiO2-Al2O3 slags containing high content of Al2O3 and Na2O in the temperature range of 1573 K to 1773 K (1300 °C to 1500 °C). The rate of loss was determined by monitoring the weight change of the slag melt by thermogravimetric analysis under isothermal conditions. As expected, the evaporation rate was found to increase with increasing the temperature. Higher basicity and larger B2O3 and Na2O concentrations were also found to increase the evaporation rate. The evaporation rate appears to be controlled by chemical reaction at the surface in the beginning, followed by a mixed reaction-mass transfer regime, and finally a liquid-phase mass transport step. The apparent activation energies for the evaporation reaction were calculated for different slag compositions.

Li, Mark; Utigard, Torstein; Barati, Mansoor

2015-02-01

25

Optical band gap studies on (55? x)Na 2O– xPbO–45P 2O 5 (SLP) glass system  

Microsoft Academic Search

Sodium lead phosphate (SLP) glasses in the series (55?x)Na2O–xPbO–45P2O5 with x varying from 55 to 0 were prepared by the single step melt quenching process with Na2CO3(sodiumcarbonate),PbO (lead monoxide) and NH4H2PO4 (ammonium dihydrogen phosphate – ADP) as starting materials. The 12 samples prepared were grouped into two batches with batch A having 55?x?30 for increasing Na2O and batch B having

K. Subrahmanyam; M. Salagram

2000-01-01

26

FT-IR and thermoluminescence investigation of P2O5-BaO-K2O glass system  

NASA Astrophysics Data System (ADS)

The 0.5P2O5?xBaO?(0.5-x)K2O glass system (0?x?0.5mol%) is investigated by FT-IR and thermoluminescence as a possible dosimetic material. FT-IR spectra show structural network modifications with the composition variations of the studied glasses. The predominant absorption bands are characterized by two broad peaks near 500 cm-1, two weak peaks around 740 cm-1 and three peaks in the 900-1270 cm-1 region. The shift in the position of the band assigned to asymmetric stretching of PO2- group, ?as(PO2-) modes from ˜1100 cm-1 to 1085 cm-1 and the decrease in its relative intensity with the increasing of K2O content shows a network modifier role of this oxide.. Luminescence investigations show that by adding modifier oxides in the phosphate glass a dose dependent TL signals result upon irradiation. Thus P2O5-BaO-K2O glass system is a possible candidate material for dosimetry in the dose 0 - 50 Gy range.

Ivascu, C.; Timar-Gabor, A.; Cozar, O.

2013-11-01

27

Lateral variation of H2O/K2O ratios in Quaternary Magma of the Northeastern Japan arc  

NASA Astrophysics Data System (ADS)

Water plays a fundamental role in the magma genesis beneath subduction zones. In order to estimate a spatial distribution of the density of water flux in the wedge mantle of the Northeastern Japan arc, this study examines a lateral variation of pre-eruptive bulk rock H2O/K2O contents among volcanoes located both in the frontal and in back arc settings. The analytical targets are the frontal volcanoes Nigorikawa (N42.12 E140.45), Zenikame (N41.74 E140.85), Adachi (N38.22 E140.65), and Nanashigure (N40.07 E141.11), and the back arc ones Hijiori (N38.61 E140.17) and Kanpu (N39.93 E139.88). The bulk magmatic H2O content (TH2O) is calculated from a mass balance of hydrogen isotopic ratios among three phases in a batch of magma; dissolved water in melt, excess H2O vapor, and hydrous phenocrysts such as amphiboles (Miyagi and Matsubaya, 2003). Since the amount of H2O in hydrous phenocryst is negligible, the bulk magmatic H2O content can be written as TH2O = (30 XD CD) / (15 - dT + dMW), where dMW is the measured hydrogen isotopic ratio of hydrous phenocrysts, XD is a melt fraction of magma, CD is a water concentration of the melt, and dT is hydrogen isotopic ratios of a bulk magma (assumed to be -50 per-mil). Both XD and CD are estimated from bulk rock chemistry of the sample using the MELTS program (Ghiorso and Sack, 1995). Hydrogen isotopic fractionation factors are assumed to be -15 and -30 per-mil for vapor and hydrous mineral, and vapor and silicate melt, respectively. There observed a clear difference among the H2O/K2O ratios of bulk magmas from the frontal and back arc volcanoes. For instance higher H2O/K2O wt ratios was observed in the frontal volcanoes (Nigorikawa 5.3, Zenikame 11-12, Adachi 8-10, and Nanashigure 4-18), while lower H2O/K2O wt ratios was observed in the back arc ones (Kanpu 0-2.5 and Hijiori 1.4). The lateral variation of H2O/K2O ratios infer the higher water flux through the frontal side of wedge mantle, which can be a potential cause of the larger quantity of volcanic products along the frontal side of the NE Japan arc. This research project has been conducted under the research contract with Nuclear and Industrial Safety Agency (NISA). I thank Drs. H. Kawaraya, D. Ishiyama, and O. Matsubaya at Akita univ. for their help in the analysis of hydrogen isotopic ratios.

Miyagi, I.

2012-12-01

28

Structural characterization and physical properties of P2O5-CaO-Na2O-TiO2 glasses by Fourier transform infrared, Raman and solid-state magic angle spinning nuclear magnetic resonance spectroscopies.  

PubMed

Phosphate-based glasses have been investigated for tissue engineering applications. This study details the properties and structural characterization of titanium ultra-phosphate glasses in the 55(P(2)O(5))-30(CaO)-(25-x)(Na(2)O)-x(TiO(2)) (0?x?5) system, which have been prepared via melt-quenching techniques. Structural characterization was achieved by a combination of X-ray diffraction (XRD), and solid-state nuclear magnetic resonance, Raman and Fourier transform infrared spectroscopies. Physical properties were also investigated using density, degradation and ion release studies; additionally, differential thermal analysis was used for thermal analysis of these glasses. The results show that with the addition of TiO(2) the density and glass transition temperature increased whereas the degradation and ion release properties are decreased. From XRD data, TiP(2)O(7) and CaP(2)O(6) were detected in 3 and 5 mol.% TiO(2)-containing glasses. Magic angle spinning nuclear magnetic resonance results confirmed that as TiO(2) is incorporated into the glass; the amount of Q(3) increases as the amount of Q(2) consequently decreases, indicating increasing polymerization of the phosphate network. Spectroscopy results also showed that the local structure of glasses changes with increasing TiO(2) content. As TiO(2) is incorporated into the glass, the phosphate connectivity increases, indicating that the addition of TiO(2) content correlates unequivocally with an increase in glass stability. PMID:21930253

Kiani, Azadeh; Hanna, John V; King, Scott P; Rees, Gregory J; Smith, Mark E; Roohpour, Nima; Salih, Vehid; Knowles, Jonathan C

2012-01-01

29

Raman Spectroscopic Study of Nd-Doped 10Na(2)O-90TeO(2) Glasses  

SciTech Connect

Tellurite glass systems have important commercial applications in optical communication due to its high refractive index, good infrared transmittance, and high optical nonlinearity. Previously, we studied optical absorption. A local Nd-O structural transition, in the vicinity of 1 mol% Nd2O3, was found; the asymmetry of Nd-O ligand field was at maximum whereas, the degree of Nd-O bond covalency was in a minimum according to the Judd-Ofelt theory derived intensity parameters of the oscillator strength. In this study, we report our investigation on the structural change in the host matrix, 10Na2O-90TeO2, as a function of Nd2O3 concentration using Raman spectroscopy technique. Over the Nd2O3 concentration region from 0.5 to 2.5 mol%, our Raman spectroscopic study showed that the addition of Nd into tellurite glass converts TeO4 trigonal bipyramid (tbp) units to TeO3 trigonal pyramid (tp) units, and possibly some terminal TeO3+1 polyhedra. The Nd effect on the speciation of tellurite structural groups is similar to that of other metal cations of monovalent, divalent, and trivalent. The previously observed Nd-O local structural transition was also found in the current study. A transition, near 1 mol% Nd2O3, was observed in the correlations, both band position and intensity, between two Raman stretching vibration bands near 600 and 730 cm-1. The low frequency band represents the stretching vibration mode of TeO4 tbp units and the high frequency band represnts the stretching vibration mode of TeO3 trigonal pyramid (tp) units. Therefore, the observed transition may suggest the formation of TeO3+1 polyhedron units in the glasses with Nd2O3 concentration greater than 1 mol%. Near 465 cm-1, the bending vibration band for Te-O-Te linkages showed a significant decrease for the glass with 2.5 mol% Nd2O3, suggesting a considerable breakage of the tellurite network.

Li, Hong; Su, Yali; Sundaram, S. K.

2001-11-01

30

A comparative study between in vivo bone ingrowth and in vitro apatite formation on Na 2O–CaO–SiO 2 glasses  

Microsoft Academic Search

This study compared in vivo bioactivity with the in vitro apatite-forming ability of biomaterials. Granules of five kinds of P2O5-free Na2O–CaO–SiO2 glasses, showing different apatite-forming ability in simulated body fluid (SBF), were implanted into a defect on the femoral condyle of rabbits. Bone ingrowth was evaluated using scanning electron microscopy among five kinds of glasses at 1, 2, 3, 6,

Shunsuke Fujibayashi; Masashi Neo; Hyun-Min Kim; Tadashi Kokubo; Takashi Nakamura

2003-01-01

31

Spectroscopic studies on Na 2O–SiO 2 glasses with different Ag concentration using silica obtained from wastes of a geothermal plant  

Microsoft Academic Search

A set of samples of Na2O–SiO2 glasses with different concentrations of Ag2O in the range of 3–6 wt% were prepared by melting. The silica used was obtained from purified residues supplied by a geothermic power station. The samples were annealed in air at 500 and 850 °C. They were characterized by optical (UV–VIS and IR spectroscopies) and X-ray diffraction analysis.

Ma. Elena Zayas; H. Arizpe-Chávez; F. J. Espinoza-Beltrán; C. D??az; L. L. D??az-Flores; J. M. Yáñez-Limón; J. González-Hernández

2003-01-01

32

Effect of SiO2/Na2O mole ratio on the properties of foam geopolymers fabricated from circulating fluidized bed fly ash  

NASA Astrophysics Data System (ADS)

Geopolymers are three-dimensional aluminosilicates formed in a short time at low temperature by geopolymerization. In this paper, alkali-activated foam geopolymers were fabricated from circulating fluidized bed fly ash (CFA), and the effect of SiO2/Na2O mole ratio (0.91-1.68) on their properties was studied. Geopolymerization products were characterized by mechanical testing, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The results show that SiO2/Na2O mole ratio plays an important role in the mechanical and morphological characteristics of geopolymers. Foam samples prepared in 28 d with a SiO2/Na2O mole ratio of 1.42 exhibit the greatest compressive strength of 2.52 MPa. Morphological analysis reveals that these foam geopolymers appear the relatively optimized pore structure and distribution, which are beneficial to the structure stability. Moreover, a combination of the Si/Al atomic ratio ranging between 1.47 and 1.94 with the Na/Al atomic ratio of about 1 produces the samples with high strength.

Liu, Ze; Shao, Ning-ning; Huang, Tian-yong; Qin, Jun-feng; Wang, Dong-min; Yang, Yu

2014-06-01

33

Removal of Boron and Phosphorus from Silicon Using CaO-SiO2-Na2O-Al2O3 Flux  

NASA Astrophysics Data System (ADS)

A combination of solvent refining and flux treatment was employed to remove boron and phosphorus from crude silicon to acceptable levels for solar applications. Metallurgical grade silicon (MG-Si) was alloyed with pure copper, and the alloy was subjected to refining by liquid CaO-SiO2-Na2O-Al2O3 slags at 1773 K (1500 °C). The distribution of B and P between the slags and the alloy was examined under a range of slag compositions, varying in CaO:SiO2 and SiO2:Al2O3 ratios and the amount of Na2O. The results showed that both basicity and oxygen potential have a strong influence on the distributions of B and P. With silica affecting both parameters in these slags, a critical P_{{{{O}}2 }} could be identified that yields the highest impurity pick-up. The addition of Na2O to the slag system was found to increase the distributions of boron and phosphorus. A thermodynamic evaluation of the system showed that alloying copper with MG-Si leads to substantial increase of boron distribution coefficient. The highest boron and phosphorus distribution coefficients are 47 and 1.1, respectively. Using these optimum slags to reduce boron and phosphorus in MG-Si to solar grade level, a slag mass about 0.3 times and 17 times mass of alloy would be required, respectively.

Li, Mark; Utigard, Torstein; Barati, Mansoor

2014-01-01

34

Optical Properties on Li2O-K2O-WO3-B2O3 Glass System  

NASA Astrophysics Data System (ADS)

Mixed alkali tungsten borate glasses xLi2O-(30-x) K2O-10WO3-60B2O3 (0 < x < 30) were prepared from the melts. These glasses were characterized using X-ray diffraction, differential scanning calorimetry and density measurements. Optical absorption studies were carried out as a function of alkali content to look for mixed alkali effect (MAE) on the spectral properties of these glasses. From the study of ultraviolet absorption edge, the optical band gap energies and Urbach energies were evaluated. The average electronic polarizability of the oxide ion, optical basicity and the interaction parameters were also evaluated for all the glasses. Many of these parameters vary non-linearly exhibiting a minima or maxima with increasing alkali concentration, indicating the mixed alkali effect. An attempt is made to interpret MAE in this glass system in terms of its glass structure.

Edukondalu, A.; Samee, M. A.; Ahmmad, Shaikh Kareem; Taqiullah, Sair Md.; Rahman, Syed; Siva Kumar, K.

35

The mixed network former effect in glasses: solid state NMR and XPS structural studies of the glass system (Na2O)(x)(BPO4)(1-x).  

PubMed

The structural organization of sodium borophosphate glasses with composition (Na(2)O)(x)(BPO(4))(1-x) (0.25 ?x? 0.55) has been investigated by differential scanning calorimetry, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), as well as single- and double resonance (11)B and (31)P magic-angle spinning (MAS) NMR. (11)B MAS-NMR data indicate the dominance of anionic four-coordinated boron units, and (31)P MAS NMR reveals the successive transformation of neutral P(3) into singly charged P(2) units and their further transformation into doubly charged P(1) units at high Na(2)O contents. The quantification of these units provides detailed insight into the competition of the network formers borate and phosphate for the network modifier oxide. At low modifier content (x < 0.35), the anionic species are almost exclusively borate (B(4)) units, whereas at higher sodium concentrations, large numbers of anionic phosphate (P(2) and P(1)) species are formed. O-1s XPS data provide a quantitative distinction between B-O-B, B-O-P, and P-O-P linkages as well as non-bridging oxygen atoms, and comparable numbers can be extracted from (11)B and (31)P MAS-NMR experiments. Both XPS as well as (31)P{(11)B} and (11)B{(31)P} rotational echo double resonance (REDOR) NMR results reveal strong interactions between the two network formers boron oxide and phosphorus oxide, resulting in a preferred formation of B-O-P linkages. For higher Na(2)O contents, however, the successive network modification diminishes this preference, resulting in close-to-statistical network connectivities. Compositional trends of T(g) in the Na(2)O-B(2)O(3)-P(2)O(5) glass forming system can be correlated with the overall network connectedness, expressed by the total number of bridging oxygen atoms per network former species. However, separate linear correlations are observed for different compositional lines, indicating also the relevance of the type of network former linkages present. PMID:21380468

Rinke, Matthias T; Eckert, Hellmut

2011-04-14

36

Physical and optical properties of Dy3+: Li2O-K2O-B2O3 glasses  

NASA Astrophysics Data System (ADS)

The luminescence, lasing and sensing properties of rare earth (RE) ions have drawn much interest among researchers. We have focussed on the physical and optical properties of Li2O-K2O-B2O3 (LKB) with different concentrations of dysprosium (Dy3+) ions. The glass samples were prepared using melt quenching method. The physical parameters of the prepared glass were determined. Optical measurements such as XRD, FTIR, absorption and photoluminescence spectra have been carried out. Dy3+: LKB glass showed eight absorption bands with hypersensitive transition located at 1265 nm (6H15/2 ? 6F11/2-6H9/2). Finally, Dy3+: LKB glass exhibited two intense luminescence emission at 481 nm (4F9/2 ? 6H15/2; blue) and 573 nm (4F9/2 ? 6H13/2; yellow) and feeble band at 683 nm (4F9/2 ? 6H11/2; red) with excitation wavelength at 370 nm. The results obtained are prevalent with others studies and also point to its use in solid-state laser, optoelectronic devices and W-LEDs application.

Azizan, S. A.; Hashim, S.; Razak, N. A.; Mhareb, M. H. A.; Alajerami, Y. S. M.; Tamchek, N.

2014-11-01

37

High-pressure x-ray diffraction studies of the nanostructured transparent vitroceramic medium K2O-SiO2-Ga2O3  

E-print Network

High-pressure x-ray diffraction studies of the nanostructured transparent vitroceramic medium K2O embedded in an amorphous matrix, in the pressure range from ambient up to 15 GPa. The optically transparent in an amorphous medium. The pressure-driven evolution of x-ray-diffraction patterns indicated a progressive

Kruger, Michael - Department of Physics, University of Missouri

38

CLAY MINERALOGY ALONG THE LATERITE PROFILE IN HUBEI, SOUTH CHINA: MINERAL EVOLUTION AND EVIDENCE FOR EOLIAN ORIGIN  

E-print Network

the values of the chemical index of alteration (CIA = Al2O3/(Al2O3+ CaO+ K2O+ Na2O)6100%) of the soil profile, in reasonable agreement with the results of the illite crystallinity and CIA index. In addition, samples from B1

Li, Zhaohui

39

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

40

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

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

41

Photoluminescence characteristics and energy transfer between Bi3+ and Eu3+ in Na2O—CaO—GeO2—SiO2 glass  

NASA Astrophysics Data System (ADS)

We report the photoluminescence (PL) of Eu3+-doped glass with Bi3+ as a sensitizer. The specific glass system with the strong enhancement of the red emission of Eu3+ is obtained by adding a small number of Bi3+ ions instead of increasing the Eu3+ concentration. The emission band of Bi3+ overlaps with the excitation band of Eu3+ and the lifetime decay curves, resulting in a very efficient energy transfer from Bi3+ to Eu3+. The probability of energy transfer is strongly dependent on Bi3+ concentration. In addition, the intensity of 4f–4f transition is much stronger than that of a charge-transfer (CT) band in the excitation spectrum, which indicates that the Na2O—CaO—GeO2-SiO2 glass is a suitable red-emitting phosphor with high stability as a candidate for light-emitting diodes (LEDs).

Li, Qian-Yue; Xu, Xu-Hui; Zhang, Bu-Hao; Wu, Yu-Mei; Qiu, Jian-Bei; Yu, Xue

2014-12-01

42

11B NMR and magnetic susceptibility of xCuO(1 - x)(2B 2O 3K 2O) glasses  

NASA Astrophysics Data System (ADS)

The temperature dependence of the magnetic susceptibility and the quadrupolar effects of xCuO(1 - x)(2B 2O 3K 2O) glasses (0 ? x ? 20 mol%) were investigated. Both measurements pointed out that these glasses are homogeneous up to a concentration of x ? 15 mol%. From Curie constants it was determined that all copper ions are in the divalent state. The quadrupolar constants increase with CuO content and saturate above the limit concentration of homogeneous glasses.

Ardelean, I.; Coldea, M.; Cozar, O.

1982-08-01

43

Phosphate glasses for tissue engineering: Part 1. Processing and characterisation of a ternary-based P2O5-CaO-Na2O glass system.  

PubMed

This paper presents the results of a study of the thermal properties, X-ray powder diffraction (XRPD), NMR and solubility of a range of phosphate-based glasses. Ion release and pH measurements were also obtained. The compositions were limited by fixing the P2O5 mol% content at 45, 50 and 55 mol%, and varying the CaO mol% at 30, 35 and 40 mol%. Initial data collected from thermal analysis showed an increase in the Tg values, with increasing CaO mol%, as expected. An increase in crystallisation temperatures with increasing CaO mol% was also observed, with sharp peaks indicating the presence of single and/or double phases. Initial XRPD data revealed that the 45 mol% P2O5 precipitated a calcium bridged trimetaphosphate (Na4Ca[PO3]6) at the sodium oxide contents of 25 and 20 mol%, but at the 15 mol% level two phases formed, NaCa[PO3]3 and Ca2P2O7. The 50 mol% P2O5 compositions showed two sodium phosphate-rich phases [NaCa(PO3)3 and NaPO3] for the lower calcium containing compositions, and a calcium phosphate phase [CaP2O6] for compositions with higher CaO mol%. The 55 mol% P2O5 compositions, exhibited similar phases for the lower calcium containing compositions, and a single calcium phosphate phase (CaP2O6) was identified for the higher calcium containing composition. NMR analysis revealed the presence of Q1 and Q2 species in the 45 mol% P2O5 compositions, and Q2 species present in the 50 and 55 mol% P2O5 compositions. The non-linear data obtained from the thermal and solubility analyses conducted were attributed to the packing density of the 45 mol% P2O5 compositions. The solubility was seen to decrease with increasing CaO mol%, for all the glasses investigated, and all the compositions showed a gradual decrease in pH with time, and this was accounted for by the release of Na+ and Ca2+ ions into solution. PMID:14585698

Ahmed, I; Lewis, M; Olsen, I; Knowles, J C

2004-02-01

44

Structural investigation in the TiB 2-(Na 2O·B 2O 3·Al 2O 3) system  

NASA Astrophysics Data System (ADS)

Composites in the TiB 2-Na 2O·B 2O 3·Al 2O 3 systems, TiB 2-MBA (MB stands for sodium metaborate and A is Al 2O 3), were prepared by self-propagating high-temperature synthesis (SHS), in simultaneous mode. Selection of these compositions was ruled by the interesting properties of both TiB 2 and double borates of alkali metal and aluminum. The structure of the obtained materials was evaluated by micro-Raman spectroscopy, from room temperature up to 600 °C, and X-ray photoelectron spectroscopy (XPS). Formation of the TiB 2 and TiO 2- xB x phases along with TiO 2 as rutile were identified as titanium speciation in the grain phase embedded in a sodium aluminum borate matrix. Integration of the Raman spectra of the grain phases revealed a TiB 2 content of 16.99% and 23.32% for the two composite investigated 2TiB 2·2MBA and 3TiB 2·5MBA. A constrained-width model for the spectral deconvolution of the high-frequency Raman band was forwarded to calculate the proportion of tetrahedral boron atoms (7.424%) in the blank borate matrix Na 2B 2O 4·Al 2O 3 in solid phase.

Buixaderas, Elena; Maria Anghel, Elena; Petrescu, Simona; Osiceanu, Petre

2010-09-01

45

Structural study of Al2O3-Na2O-CaO-P2O5 bioactive glasses as a function of aluminium content  

NASA Astrophysics Data System (ADS)

Calcium phosphate based biomaterials are extensively used in the context of tissue engineering: small changes in composition can lead to significant changes in properties allowing their use in a wide range of applications. Samples of composition (Al2O3)x(Na2O)0.11-x(CaO)0.445(P2O5)0.445, where x = 0, 0.03, 0.05, and 0.08, were prepared by melt quenching. The atomic-scale structure has been studied using neutron diffraction and solid state 27Al MAS NMR, and these data have been rationalised with the determined density of the final glass product. With increasing aluminium concentration the density increases initially, but beyond about 3 mol. % Al2O3 the density starts to decrease. Neutron diffraction data show a concomitant change in the aluminium speciation, which is confirmed by 27Al MAS NMR studies. The NMR data reveal that aluminium is present in 4, 5, and 6-fold coordination and that the relative concentrations of these environments change with increasing aluminium concentration. Materials containing aluminium in 6-fold coordination tend to have higher densities than analogous materials with the aluminium found in 4-fold coordination. Thus, the density changes may readily be explained in terms of an increase in the relative concentration of 4-coordinated aluminium at the expense of 6-fold aluminium as the Al2O3 content is increased beyond 3 mol. %.

Smith, J. M.; King, S. P.; Barney, E. R.; Hanna, J. V.; Newport, R. J.; Pickup, D. M.

2013-01-01

46

Influence of rare-earth ions on SiO2-Na2O-RE2O3 glass structure  

NASA Astrophysics Data System (ADS)

Praseodymium and europium sodium silicate glasses of nominal composition (SiO2)0.70 - x(Na2O)0.30(RE2O3)x, where RE is the rare earth and 0 <= x <= 0.10, were studied by neutron and high-energy x-ray scattering and classical molecular dynamics simulations. The observation of a significant x-ray intensity in doped as compared to un-doped glasses is indicative of RE-RE correlations at a distance of ~ 3.7-3.9 Å, much shorter than would be expected for a homogeneous distribution, suggesting that clustering of the rare-earth cations occurs in both these glass systems at low concentrations. Above x = 0.075 (nominal), minimal changes in this region indicate that the RE atoms are incorporated much more randomly into the glass structure. The molecular dynamics simulations suggest that the rare-earth ions enter the sodium-rich regions in the sodium silicate glasses and act as modifiers. A cluster analysis performed on the model systems indicates that the tendency for clustering is higher in praseodymium-containing glasses than in the europium glasses.

Johnson, J. A.; Benmore, C. J.; Holland, D.; Du, J.; Beuneu, B.; Mekki, A.

2011-02-01

47

Influence of fluoride additions on biological and mechanical properties of Na2O-CaO-SiO2-P2O5 glass-ceramics.  

PubMed

Two series of Na2O-CaO-SiO2-P2O5 glass-ceramics doped with NH4HF2 (G-NH4HF2) or CaF2 (G-CaF2) have been prepared by sol-gel method. The glass-ceramic phase composition and morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). The mechanical properties and thermal expansion coefficient were measured by a microhardness tester, an electronic tensile machine and a thermal expansion coefficient tester. The structure difference between these two glass-ceramics was investigated by Fourier transform infrared spectroscopy (FTIR), and the in vitro bioactivity of the glass-ceramics was determined by in vitro simulated body fluid (SBF) immersion test. The hemolysis test, in vitro cytotoxicity test, systemic toxicity test and the implanted experiment in animals were used to evaluate the biocompatibility of the glass-ceramics. The mechanical properties of sample G-NH4HF2 are lower than that of sample G-CaF2, and the bioactivity of sample G-NH4HF2 is better than that of sample G-CaF2. The thermal expansion coefficients of these two glass-ceramics are all closer to that of Ti6Al4V. After 7 days of SBF immersion, apatites were induced on glass-ceramic surface, indicating that the glass-ceramics have bioactivity. The hemolysis test, in vitro cytotoxicity test and systemic toxicity test demonstrate that the glass-ceramics do not cause hemolysis reaction, and have no toxicity to cell and living animal. The implanted experiment in animals shows that bone tissue can form a good osseointegration with the implant after implantation for two months, indicating that the glass-ceramics are safe to serve as implants. PMID:24411365

Li, H C; Wang, D G; Hu, J H; Chen, C Z

2014-02-01

48

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

PubMed

Na2O-CaO-B2O3-P2O5 glasses have been prepared by the melt-quenching method. B2O3 content was systematically increased from 5 to 30mol%, 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 30days. 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. PMID:25748986

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

2015-06-01

49

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

NASA Astrophysics Data System (ADS)

Phosphate glasses in the compositions of 70P 2O 5-15Al 2O 3-14Na 2O-1RE 3+ (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 bands in visible and near-infrared (NIR) region. From the measured absorption spectra, Judd-Ofelt (J-O) intensity parameters ( ?2, ?4 and ?6) have been calculated for all the studied ions. For Sm 3+ doped glass, four emission bands centered at 562 nm ( 4G 5/2 ? 6H 5/2), 598 nm ( 4G 5/2 ? 6H 7/2), 644 nm ( 4G 5/2 ? 6H 9/2), and 704 nm ( 4G 5/2 ? 6H 11/2) have been observed with 402 nm ( 6H 5/2 ? 4F 7/2) excitation wavelength. Of them, 598 nm ( 4G 5/2 ? 6H 7/2) has shown a bright orange emission. With regard to Dy 3+ doped glass, a blue emission band centered at 486 nm ( 4F 9/2 ? 6H 15/2) and a bright yellow emission at 575 nm ( 4F 9/2 ? 6H 13/2) have been observed, apart from 662 nm ( 4F 9/2 ? 6H 11/2) emission transition with an excitation at 388 nm ( 6H 15/2 ? 4I 13/2, 4F 7/2) wavelength. Emission bands of 650 nm ( 1G 4 ? 3F 4) and 785 nm ( 1G 4 ? 3H 5) transitions for the Tm 3+ doped glass, with an excitation wavelength at 466 nm ( 3H 6 ? 1G 4), have also been observed. The stimulated emission cross-sections of all the emission bands of RE 3+ glasses (RE = Sm, Dy, and Tm) have been computed based on their measured full-width at half maximum (FWHM, ??) and measured lifetimes ( ? m).

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

2009-08-01

50

Viscosities of melts in the Na 2O?FeO?Fe 2O 3?SiO 2 system and factors controlling relative viscosities of fully polymerized silicate melts  

NASA Astrophysics Data System (ADS)

The viscosity-temperature relationships of nine melts in the Na 2O?FeO?Fe 2O 3?SiO 2 system (in equilibrium with air) have been measured in the temperature range of 1450-800°C, using the concentric cylinder method. 57Fe Mössbauer spectra were obtained on quenched samples and show that all melts with ? 20 mole% ferrite component contain ? 95% Fe as tetrahedrally-coordinated ferric ions. The compositions investigated lie along the SiO 2?NaFeO 2 and Na 2Si 4O 9?Na 6Fe 4O 9 joins. The viscosities of m decrease strongly with decreasing silicate content along these joins. In contrast, the temperature dependence of viscosity does not vary significantly along these joins. Comparison with equivalent melt compositions (related by the trivalent cation exchange operators AlFe -1, BFe -1 and GaFe -1) in the Na 2O?Al 2O 3?SiO 2, Na 2O?B 2O 3?SiO 2 and Na 2O-Ga 2O 3 viscosities decrease in the order aluminosilicate > ferrosilicate, (galliosilicate ?) > borosilicate. Thp electronegativities of the trivalent cations are inversely correlated with the relative viscosities of melts in these systems. Similarly, the electronegativities of network-stabilizing cations are inversely correlated with melt viscosity for alkali and alkaline-earth aluminosilicate melt systems. The variation in the viscosity of tectosilicate melts is correlated with estimated average T-O-T bond angles, and exothermic heats of solution of quench glasses. Structural controls of viscosity discussed are tetrahedral ordering and relative bond strengths. The acmite component in natural, peralkaline, silicic volcanics will not contribute directly to high melt viscosities for these lavas.

Dingwell, Donald B.; Virgo, David

1988-02-01

51

Acoustic velocity measurements on Na 2O-TiO 2-SiO 2 liquids: Evidence for a highly compressible TiO 2 component related to five-coordinated Ti  

NASA Astrophysics Data System (ADS)

Longitudinal acoustic velocities were measured at 1 bar in 10 Na 2O-TiO 2-SiO 2 (NTS) liquids for which previous density and thermal expansion data are reported in the literature. Data were collected with a frequency-sweep acoustic interferometer at centered frequencies of 4.5, 5, and 6 MHz between 1233 and 1896 K; in all cases, the sound speeds decrease with increasing temperature. Six of the liquids have a similar TiO 2 concentration (˜25 mol %), so that the effect of varying Na/Si ratio on the partial molar compressibility of the TiO 2 component can be evaluated. Theoretically based models for ?T and (? V/? P) T as a function of composition and temperature are presented. As found previously for the partial molar volume of TiO 2(V) in sodium silicate melts, values of ? (13.7-18.8 × 10 -2/GPa) vary systematically with the Na/Si and Na/(Si + Ti) ratio in the liquid. In contrast values of ? for the SiO 2 and Na 2O components (6.6 and 8.0 × 10 -2/GPa, respectively, at 1573 K) are independent of composition. Na 2O is the only component that contributes to the temperature dependence of the compressibility of NTS liquids (1.13 ± 0.04 × 10 -4/GPa K). The results further indicate that the TiO 2 component is twice as compressible as the Na 2O and SiO 2 components. The enhanced compressibility of TiO 2 appears to be related to the abundance of five-coordinated Ti ( [5]Ti) in these liquids, but not with a change in Ti coordination. Instead, it is proposed that the asymmetric geometry of [5]Ti in a square pyramidal site promotes different topological rearrangements in alkali titanosilicate liquids, which lead to the enhanced compressibility of TiO 2.

Liu, Qiong; Lange, Rebecca A.; Ai, Yuhui

2007-09-01

52

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

53

CAOS: Code for Adaptive Optics Systems  

NASA Astrophysics Data System (ADS)

The CAOS "system" (where CAOS stands for Code for Adaptive Optics Systems) is properly said a Problem Solving Environment (PSE). It is essentially composed of a graphical programming interface (the CAOS Application Builder) which can load different packages (set of modules). Current publicly distributed packages are the Software Package CAOS (the original adaptive optics package), the Software Package AIRY (an image-reconstruction-oriented package - AIRY stands for Astronomical Image Restoration with interferometrY), the Software Package PAOLAC (a simple CAOS interface for the analytic IDL code PAOLA developed by Laurent Jolissaint - PAOLAC stands for PAOLA within Caos), and a couple of private packages (not publicly distributed but restricted to the corresponding consortia): SPHERE (especially developed for the VLT planet finder SPHERE), and AIRY-LN (a specialized version of AIRY for the LBT instrument LINC-NIRVANA). Another package is also being developed: MAOS (that stands for Multiconjugate Adaptive Optics Simulations), developed for multi-reference multiconjugate AO studies purpose but still in a beta-version form.

Carbillet, M.; Verinaud, C.; Femenia, B.; Riccardi, A.; Fini, L.

2011-06-01

54

Preparation of K 2O?Sm 2O 3? nSiO 2-based solid-state electrolyte and its application to electrochemical CO 2 gas sensor  

Microsoft Academic Search

Ceramic-glass composites (K2O?Sm2O3?nSiO2) may be produced directly by the sintering of starting mixtures. The ionic conductivity is lowered with an increase in SiO2 content for the sample with hexagonal structure. The CO2-sensing characteristics of an electrochemical gas sensor with a structure expressed as Pt?K2O?Sm2O3?nSiO2?Na2CO3?Pt, CO2 have been investigated in terms of a two-electron electrochemical reaction. The e.m.f. is sensitive to

Yoshihiko Sadaoka; Susumu Nakayama; Yoshiro Sakai; Makoto Wake

1995-01-01

55

Preparation of glass fibres of the ZrO 2 SiO 2 and Na 2 O-ZrO 2 SiO 2 systems from metal alkoxides and their resistance to alkaline solution  

Microsoft Academic Search

Glass fibres of the ZrO2-SiO2 and Na2O-ZrO2-SiO2 systems containing up to 33 wt% ZrO2 were prepared by a non-melting technique using zirconium n-propoxide, sodium methoxide and silicon tetraethoxide as raw materials. The mixed alkoxide solutions were exposed to moist air for hydrolysis. The fibrous gels were drawn from these solutions in the course of hydrolysis, and converted to the corresponding

K. Kamiya; S. Sakka; Y. Tatemichi

1980-01-01

56

Formation of hydroxyapatite onto glasses of the CaO-MgO-SiO2 system with B2O3, Na2O, CaF2 and P2O5 additives.  

PubMed

New bioactive glasses with compositions based on the CaO-MgO-SiO(2) system and additives of B(2)O(3), P(2)O(5), Na(2)O, and CaF(2) were prepared. The in vitro mineralization behaviour was tested by immersion of powders or bulk glasses in simulated body fluid (SBF). Monitoring of ionic concentrations in SBF and scanning electron microscopy (SEM) observations at the surface of the glasses were conducted over immersion time. Raman and infrared (IR) spectroscopy shed light on the structural evolution occurring at the surface of the glasses that leads to formation of hydroxyapatite. PMID:16309741

Agathopoulos, S; Tulyaganov, D U; Ventura, J M G; Kannan, S; Karakassides, M A; Ferreira, J M F

2006-03-01

57

Effects of CaO/P2O5 ratio on the structure and elastic properties of SiO2-CaO-Na2O-P2O5 bioglasses.  

PubMed

The evolution of elastic properties and structure upon the change of CaO/P(2)O(5) ratio in SiO(2)-CaO-Na(2)O-P(2)O(5) glasses (45S5-derived and 55S4-derived) at ambient conditions has been studied by using both Brillouin and Raman spectroscopy coupled with X-ray diffraction. Under the same SiO(2)/Na(2)O ratio, it is found that a decrease in CaO/P(2)O(5) molar ratio has caused a more-polymerized silicate network via a net consumption of Q(0), Q(1), and Q(2) species yet enriching in Q(3) and Q(4) species. Brillouin experiments revealed that all the bulk, shear and Young's moduli of the glasses studied increases with the increase of CaO/P(2)O(5) molar ratio. The unexpected variation trend in shear modulus can be correlated to the contribution from cohesion, the less-polymerized phosphate Q species, and density. Compared to the 45S5-derived, the more-polymerized 55S4-deived glass has a lower bulk but slightly higher shear modulus at the given CaO/P(2)O(5) ratio. PMID:22109904

Lin, Chung-Cherng; Chen, Shih-Fan; Leung, Kak Si; Shen, Pouyan

2012-02-01

58

A classification of lunar rock and glass samples using the G -mode central method  

Microsoft Academic Search

We have used theG-mode central method to classify sets of major oxide chemical data of lunar rocks (163 averages) and lunar glasses (921 separate analyses). These data were selected from the Lunar Data Base using the following criteria: (1) the amount of SiO2, Al2O3, TiO2, FeO, MgO, CaO, Na2O, and K2O were measured by the same group of investigators and

R. Bianchi; J. C. Butler; A. Coradini; A. I. Gavrishin

1980-01-01

59

A-type granites: geochemical characteristics, discrimination and petrogenesis  

Microsoft Academic Search

New analyses of 131 samples of A-type (alkaline or anorogenic) granites substantiate previously recognized chemical features, namely high SiO2, Na2O+K2O, Fe\\/Mg, Ga\\/Al, Zr, Nb, Ga, Y and Ce, and low CaO and Sr. Good discrimination can be obtained between A-type granites and most orogenic granites (M-, I and S-types) on plots employing Ga\\/Al, various major element ratios and Y, Ce,

Joseph B. Whalen; Kenneth L. Currie; Bruce W. Chappell

1987-01-01

60

Geochemistry of shales from the Archean (~3.0 Ga) Buhwa Greenstone Belt, Zimbabwe: Implications for provenance and source-area weathering  

Microsoft Academic Search

Phyllites from the Archean (~3.0 Ga) Buhwa Greenstone Belt, Zimbabwe, were deposited on a stable cratonic platform. Analyses of the phyllites generally define a single geochemical group based on major-and trace-element abundances. The phyllites are strongly depleted in CaO, Na2O, and Sr with respect to average Archean upper crust. By contrast, K2O, Ba, and Rb are enriched several times relative

Christopher M. Fedo; Kenneth A. Eriksson; Eirik J. Krogstad

1996-01-01

61

Introduction and motivation ARTIST and CAOS online tests  

E-print Network

Introduction and motivation ARTIST and CAOS online tests Back to the questions Use of ARTIST nhorton@email.smith.edu http://www.math.smith.edu/nhorton/artisttalk.pdf Nicholas J. Horton Use of ARTIST and CAOS assessments in introductory statistics #12;Introduction and motivation ARTIST and CAOS online

Horton, Nicholas

62

Raman spectroscopic investigations of the oxide glass system (1 - x)(3B 2O 3·K 2O) xMO (MO = V 2O 5 or CuO)  

NASA Astrophysics Data System (ADS)

The influence of the V 2O 5 and CuO content on the structure of the 3B 2O 3·K 2O glass was investigated by Raman spectroscopy. The addition of vanadium oxide in the 3B 2O 3·K 2O glass causes breaking of the regular structure of the rings (borate and boroxol) and the appearance of orthoborate groups, while the addition of copper oxide determines the appearance of new structural groups. With the increase of V 2O 5 or CuO concentration, a modification of the ratio of BO 4 and BO 3 units was observed, it first increases until x ? 0.027 for V 2O 5 and x ? 0.023 for CuO and then decreases. From these results we conclude that the vanadium and copper ions act as network modifiers in these glasses.

Maniu, D.; Ardelean, I.; Iliescu, T.; Cinta, S.; Cozar, O.

1997-06-01

63

Caos en sistemas clásico-cuánticos  

NASA Astrophysics Data System (ADS)

Una de las formas de estudiar la existencia de caos en el comportamiento de un sistema clásico-cuántico, es truncando el espacio de Hilbert del sistema cuántico. El objetivo de este trabajo es analizar como afecta dicho truncamiento en la dinámica del sistema. Para tal fin se propone un Hamiltoniano integrable, cuyos valores de expectación asociados a coordenadas y momentos cuánticos responden, por el teorema de Ehrenfest, a un sistema de dos osciladores clásicos con acoplamiento lineal.

Dirani, L. D.; Núñez, J. A.

64

Na2O and Trace Elements Behavior in Trachytes and Phonolites at Suswa Volcano, Kenya: the Result of Combined Magma Mixing and Volatile-rich Na-Trace Element Fluids  

NASA Astrophysics Data System (ADS)

The evolution of Suswa, a Quaternary volcano in the Kenya Rift, was dominated by the eruption of two rock suites, separated by a caldera event. Suswa is part of the Central Kenya Peralkaline Province (CKPP), which includes the Greater Olkaria Volcanic Complex (GOVC) and inter-center mafic fields, e.g. Tandamara and Elmenteita, whose compositions range from basalt to basaltic trachy-andesite (BTA). Both suites at Suswa range from trachyte to phonolite, but are distinguished by the amount of SiO2: pre- and syn-caldera rocks have 60-62%, and post-caldera rocks 57-59%. Trachyte to phonolite trends within each suite result from increasing Na2O, which is accompanied by increases in a number of trace elements (Be, Hf, Nb, Rb, Th, Y, Zn, Zr, and REE, except Eu). Magmatic processes included magma mixing, in which BTA magma similar to those of Tandamara and Elmenteita intruded the pre-caldera Suswa trachytic chamber, and fluid complexing, which was responsible for the enrichment in Na2O and trace elements. The importance of magma mixing in the CKPP has been recently documented at the GOVC by Macdonald et al. (2008, J Pet 49, 1515-1547), for which mafic-intermediate magmatic inclusions within comendites and disequilibrium phenocryst assemblages are part of the evidence. Evidence for mixing at Suswa includes: 1) mixed feldspar assemblages, e.g. syn-caldera ignimbrite samples contain both alkali feldspar (An2Ab62Or36), and xenocrystic plagioclase (An45Ab52Or3), and 2) heterogeneous matrix glass compositions. Glass in pre-caldera rocks is trachytic, similar to whole-rock compositions. Syn-caldera rocks have glass compositions both trachytic and intermediate between trachyte and BTA, while Tandamara BTA rocks contain trachytic glass. Glass in post-caldera rocks is mostly phonolitic. Glass inclusions in plagioclase xenocrysts are basaltic, similar to flows in the area. X-Y elemental plots do not show linear trends, as would be predicted from a mixing process. We attribute this to the short time scale between mixing and eruption. Experimental studies by De Campos et al. (2008, Chem Geol) and Perugini et al. (2008, Chem Geol) show that short time scales of mixing result in insufficient time for diffusion of elements to distribute linearly. The second important process at Suswa is halogen complexing, evidence for which includes: 1) High concentrations of F in matrix glass. For instance, syn-caldera matrix glass F varies from 0.5% for an early phreatomagmatic group to 1 - 2% for a later ring feeder and fissure eruptions, and post-caldera rocks have 0.5%, increasing to 1% from early to late eruptions; 2) Precipitation of LREE-rich fluorapatite and fluorite in the groundmass in syn-caldera rocks, and fluorapatite as a daughter mineral in melt inclusions in post-caldera rocks; 3) A positive correlation between Na2O and F in melt inclusions and matrix glasses. Macdonald et al. (1993, CMP 114, 276-287) documented immiscible carbonatite in syn-caldera trachytes from Suswa. Buhn and Rankin (1999, GCA 63, 3781-3797) showed that interaction with Na -F -REE - trace element-bearing carbonatitic fluids in Namibia resulted in enrichment of magmas with Na and trace elements similar to those observed at Suswa.

Espejel-Garcia, V. V.; Anthony, E. Y.; Ren, M.; MacDonald, R.; Skilling, I. P.; White, J. C.

2008-12-01

65

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)

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.

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

2009-08-01

66

Strutural characterization of Eu2O3-MgO-Na2O-Al2O3-SiO2 glasses with varying Al2O3 content: Raman, NMR and Brillouin spectroscopy studies  

NASA Astrophysics Data System (ADS)

Raman, NMR (27Al and 29Si) and Brillouin spectroscopies are used to investigate the structure of 14.80Na2O-11.84MgO-1.26Eu2O3-xAl2O3-(72.10-x)SiO2 glasses with varying Al2O3 content (x = 0, 2.96, 5.92, 8.88, 14.80 mole cm-1) and 29Si NMR single peak show that the overall number of Si-O-T linkages (T = Al, Si) increases with the reduction in the number of Si-O- bonds when the alumina-to-silica ratio is increased. The narrowing of the 29Si line favors the Na+ charge compensation of [AlO4]- tetrahedra and is in agreement with ordering of the aluminosilicate ring structural network deduced from the Raman mid-frequency vibrations. 27Al NMR spectra show that tetrahedral coordination of Al atoms is the only one present in these glasses. Brillouin scattering results indicate that the glass structure becomes harder and more polarizable as the alumina content within the glass is increased.

Utegulov, Z. N.; Eastman, M. A.; Shen, G.-Q.; Prabakar, S.; Mueller, K. T.; Wicksted, J. P.

2003-03-01

67

Investigating the influence of Na(+) and Sr (2+) on the structure and solubility of SiO 2-TiO 2-CaO-Na 2O/SrO bioactive glass.  

PubMed

This study was conducted to determine the influence that network modifiers, sodium (Na(+)) and strontium (Sr(2+)), have on the solubility of a SiO2-TiO2-CaO-Na2O/SrO bioactive glass. Glass characterization determined each composition had a similar structure, i.e. bridging to non-bridging oxygen ratio determined by X-ray photoelectron spectroscopy. Magic angle spinning nuclear magnetic resonance (MAS-NMR) confirmed structural similarities as each glass presented spectral shifts between -84 and -85 ppm. Differential thermal analysis and hardness testing revealed higher glass transition temperatures (Tg 591-760 °C) and hardness values (2.4-6.1 GPa) for the Sr(2+) containing glasses. Additionally the Sr(2+) (~250 mg/L) containing glasses displayed much lower ion release rates than the Na(+) (~1,200 mg/L) containing glass analogues. With the reduction in ion release there was an associated reduction in solution pH. Cytotoxicity and cell adhesion studies were conducted using MC3T3 Osteoblasts. Each glass did not significantly reduce cell numbers and osteoblasts were found to adhere to each glass surface. PMID:25644099

Li, Y; Placek, L M; Coughlan, A; Laffir, F R; Pradhan, D; Mellott, N P; Wren, A W

2015-02-01

68

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

NASA Astrophysics Data System (ADS)

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).

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

69

Silicate speciation in H2O-Na2O-SiO2 fluids from 3 to 40 mol% SiO2, to 600 °C and 2 GPa  

NASA Astrophysics Data System (ADS)

The silicate speciation in H2O-Na2O-SiO2 fluids was studied in situ up to 600 °C and 2.0 GPa using Raman spectroscopy and a Bassett-type hydrothermal diamond-anvil cell. Fluid compositions ranged from 3 to 40 mol% SiO2, with various Na/Si ratios. The main trends observed in Raman spectra of fluids with increasing SiO2 concentration include (1) decrease in the intensity of the ?770 cm-1 band (monomer, Q0, symmetric stretch); (2) increase in the intensity of the ?1050 cm-1 band (bridging oxygen Si-O-Si antisymmetric stretch) and the bands at ?450-600 cm-1 (bridging oxygen Si-O-Si bending modes); and (3) increase in spectral contributions at ?800-1000 cm-1 from stretching vibrations of Q1, Q2 and Q3 species. These trends are interpreted to represent decrease in the proportion of Q0 monomers, and increase in the proportions of Q1 and Q2 (±Q3) species, with increasing silicate concentration in the fluid up to 40 mol% SiO2. Raman spectra in the range of tetrahedral Si-O stretching vibrations (700-1200 cm-1) exhibit little discernable difference with changing Na/Si ratio, when compared at constant molar concentration of SiO2. Particularly at lower Na/Si ratio, increasing silicate concentration also results in increasing relative intensity of the Raman signal of O-H stretching vibrations at about 3300 cm-1, suggesting increased intermolecular hydrogen bonding between H2O molecules and/or oxygen atoms belonging to silicate species. These results suggest that silicate in hydrous fluids in the deep Earth remains occurs predominately as partly polymerized, Q1 and Q2 species up to high silicate concentrations, providing an opportune medium for mobilizing high field-strength and other elements in the lithosphere.

Steele-MacInnis, Matthew; Schmidt, Christian

2014-07-01

70

Cao Gío (coin rubbing). Vietnamese attitudes toward health care.  

PubMed

Cao gío is the Vietnamese practice of rubbing the skin with a coin to alleviate various common symptoms of illness. The back, neck, head, shoulder, and chest are common sites of application. Although mimicking the lesions of trauma, it is not a harmful procedure, and no complications are known. A survey of 50 Vietnamese living in the United States since 1975 and 1976 has shown marked distrust of American Physicians, owing largely to actual or perceived criticism of cao gío. Acceptance of cao gío as a valid cultural practice will facilitate compliance and adequate medical follow-up. PMID:7441861

Yeatman, G W; Dang, V V

1980-12-19

71

EPR and magnetic susceptibility studies of the interaction between Cu 2+ and Mn 2+ ions in x(CuO·MnO)(1-x)[2B 2O 3·K 2O] glasses  

NASA Astrophysics Data System (ADS)

EPR and magnetic susceptibility experiments have been performed on x(CuO·MnO)(1- x)[2B 2O 3·K 2O] glasses with x varying in the range 0? x?50 mol.%. For x?3 mol.% both Cu 2+ and Mn 2+ ions are present mostly as the isolated species. The increase of the g-tensor values and bonding parameters (? 2, ? 2, ? 2) for Cu 2+ ions together with the increase of TM ions concentration in the 0.2-1 mol.% range was noticed. In the case of 5 ? x ? 30 mol.% the dipole-dipole and superexchange interactions occur between transition metal ions, the first type of interactions prevailing in this range of concentration. For x30 mol.% the superexchange interaction prevail. The strong interaction between Cu 2+ and Mn 2+ gives rise to the exchange coupled Cu 2+?Mn 2+ pairs in the studied glasses with x 3 mol.%.

Cozar, O.; Ardelean, I.; Ilonca, Gh.

1982-11-01

72

Correlations in Single Molecule Photon Statistics: Renewal Indicator Jianshu Cao  

E-print Network

Correlations in Single Molecule Photon Statistics: Renewal Indicator Jianshu Cao Department be revealed through single molecule photon statistical analysis. The standard Poisson indicator defined the transfer matrix method to demonstrate the difference between the two indicators. The relationship between

Cao, Jianshu

73

Antimicrobial Principles of Xian he cao (Agrimonia pilosa).  

PubMed

From the antimicrobially active extract of the Chinese crude drug, Xian he cao ( AGRIMONIA PILOSA Ledb.), four active compounds were isolated. They were all phloroglucinol derivatives and their structures were elucidated on the basis of spectroscopic data. PMID:17262333

Yamaki, M; Kashihara, M; Ishiguro, K; Takagi, S

1989-04-01

74

Temperature-dependent luminescence and temperature-stimulated NIR-to-VIS up-conversion in Nd3+-doped La2O3-Na2O-ZnO-TeO2 glasses  

NASA Astrophysics Data System (ADS)

Telluride glasses of the composition xNd2O3-(7-x)La2O3-3Na2O-25ZnO-65TeO2, where (0?x?7) were prepared by the melt quench technique. Some physical and optical properties of the glasses were evaluated. The thermal behavior i.e. glass transition and crystallization temperatures were studied by using TGA-DTA technique. Optical properties of Nd3+-doped telluride glasses were investigated between 298 and 700 K. Basing on the obtained values of J-O parameter values (×10-20 cm2: ?2=4.49±0.84, ?4=5.03±0.61, ?6=4.31±0.73), the radiative transition probabilities (AT), radiative lifetimes (?R), fluorescence branching ratios (?) and emission cross-sections (?em) were calculated for the 4F3/2?4IJ/2 (where J=9, 11 and 13) transitions of Nd3+ ions. The ?R value of the 4F3/2 level amount to 164 ?s and is slightly higher than the measured decay time of 162 ?s. With the increasing of Nd2O3 concentration from 0.5 to 7.0 mol% the experimental lifetime of the fluorescent level decreases from 162 to 5.6 ?s. The estimated quantum efficiency amount to 100%, based on a comparison of ?R and the experimental decay time of a slightly doped Nd3+ telluride glass. An analysis of the non-radiative decay was based on the cross-relaxation mechanisms. The 4F3/2?4I9/2 and 4F5/2?4I9/2 transitions were analyzed with respect to the fluorescence intensity ratio (FIR) and were found to be temperature dependent. Infrared-to-visible up-conversion emissions with a maximum at 603.0 and 635.3 nm were observed at high temperatures using the 804 nm excitation and are due to the 4G5/2?4I9/2 and 4G5/2?4I11/2 transitions of Nd3+ ions, respectively. The near quadratic dependence of fluorescence on excitation laser power confirms that two photons contribute to up-conversion of the orange emissions. The temperature-stimulated up-conversion excitation processes have been analyzed in detail. The optical results indicate that the investigated glasses are potentially applicable as a 1063 nm laser host as well as an optical sensor for temperature measurements.

Sobczyk, Marcin

2013-04-01

75

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

PubMed

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

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

2013-12-27

76

The CAOS problem-solving environment: recent developments  

NASA Astrophysics Data System (ADS)

We present recent developments of the CAOS problem-solving environment (PSE), an IDL-based software tool whose original aim was to define and simulate as realistically as possible the behavior of a generic adaptive optics (AO) system -from the atmospheric propagation of light, to the sensing of the wave-front aberrations and the correction through a deformable mirror- but which results in a widely more general tool now. In fact, the different developments made through the last years result in a very versatile numerical tool complete of a global graphical interface (the CAOS Application Builder), a general utilities library (the CAOS Library), and different packages dedicated to a wide range of astronomical-optics-related scientific topics: the original package designed for end-to-end AO system simulations (the Software Package CAOS), an image simulation/ reconstruction package with interferometric capabilities (the Software Package AIRY), an extension of the latter specialized for the LBT instrument LINC-NIRVANA (the Software Package AIRY-LN), an ad hoc package dedicated to the VLT instrument SPHERE (the Software Package SPHERE), and an embedment of the analytical AO simulation code PAOLA (the Software Package PAOLAC).We present the status of the whole CAOS PSE, together with the most recent developments, and plans for the future of the overall tool.

Carbillet, Marcel; Desiderà, Gabriele; Augier, Evelyne; La Camera, Andrea; Riccardi, Armando; Boccaletti, Anthony; Jolissaint, Laurent; Ab Kabir, Diyana

2010-07-01

77

Optical and fluorescence spectroscopy of Eu2O3-doped P2O5-K2O-KF-MO-Al2O3 (M = Mg, Sr and Ba) glasses  

NASA Astrophysics Data System (ADS)

Fluorophosphate glasses of composition, P2O5 + K2O + KF + MO + Al2O3 + xEu2O3 (M = Mg, Sr and Ba; x = 0.01, 0.05, 0.1, 1.0, 2.0, 4.0 and 6.0 mol%) were prepared and characterized their optical properties. Crystal-field (CF) analysis revealed a relatively weak CF strength around Eu3+ ions in the Ba based fluorophosphate glasses. The Judd-Ofelt parameters have been estimated from the oscillator strengths of 7F0 ? 5D2, 7F0 ? 5D4 and 7F0 ? 5L6 absorption transitions of Eu3+ ions and were used to evaluate the radiative properties of the 5D0 ? 7FJ (J = 0-4) transitions. Considerable variation has been observed in the relative intensity ratio of 5D0 ? 7F2 to 5D0 ? 7F1 transitions of Eu3+ ions due to change in the alkaline earth metal ions. The decay of the 5D0 level shows single exponential and less sensitive to Eu3+ ions concentration as well as MgO/SrO/BaO modifiers.

Kumar, K. Upendra; Babu, S. Surendra; Rao, Ch. Srinivasa; Jayasankar, C. K.

2011-06-01

78

[Structure and luminescence properties of Eu3+ complexes with benzoic acid and 1,10-phenanthroline incorporated in SiO2, SiO2-B2O3 and SiO2-B2O3-Na2O matrices].  

PubMed

Eu3+ Complexes with benzoic acid and 1,10-phenanthroline incorporated in SiO2, SiO2-B2O3 and SiO2-B2O3-Na2O matrices were prepared via the sol-gel method. Eu-doped SiO2, SiO2-B2O3 and SiO2-B2O3-Na2O luminescence materials were synthesized. The luminescence of Eu3+ was studied with excitation spectra and emission spectra. Different forms of dopants could influence the luminescence properties. The structure of Eu-doped glass was studied by comparing IR, TEM and XRD. The results showed that after the materials were annealed at 1 000 degrees C the structure was very stable because ingredient was already removed totally. The emission spectrum showed that the typical optical spectrum of Eu3+ is 5D0 --> 7Fj (j = 1, 2) at 588 nm and 614 nm. Comparing EuCl3 with Eu3+ complexes with benzoic acid and 1,10-phenanthroline as dopant, the latter has strong luminescence property though it has small mass fraction. The luminescence intensity of Eu(3+)-doped SiO2-B2O3 glass material was weaker than that of Eu(3+)-doped SiO2 glass material, and the former's spectrum showed that there were Si-O-B bonds. The luminescence intensity of Eu3+ was quenched by this kind of structure. The luminescence intensity of Eu(3+)-doped SiO2-B2O3-Na2O glass material was greatly increased, and the infrared spectrum illustrated that there was not vibration absorption of Si-O-B bonds. Probably Na replaced B, and Si-O-Na bonds formed. This kind of structure could enhance luminescence intensity of Eu3+ to some extend. PMID:16883841

Wang, Xi-Gui; Wu, Hong-Ying; Zhao, Si-Qin; Weng, Shi-Fu; Wu, Jin-Guang

2006-05-01

79

The CAOS problem-solving environment: last news  

NASA Astrophysics Data System (ADS)

We present recent developments of the CAOS problem-solving environment (PSE), an IDL-based software tool complete of a global graphical interface, a general utilities library, and different specialized scientific packages going from end-to-end and analytical simulations to image simulation/reconstruction, with specialization to given instruments.

Carbillet, M.; Desiderà, G.; Augier, É.; La Camera, A.; Riccardi, A.; Boccaletti, A.; Jolissaint, L.; Ab Kadir, D.

2010-12-01

80

Style Components Ari Shapiro Yong Cao Petros Faloutsos  

E-print Network

the animator to edit directly the style of a motion in intuitive ways. This is the focus of our work. WeStyle Components Ari Shapiro Yong Cao Petros Faloutsos University of California, Los Angeles Figure 1: A sneaky style component is added to a normal walk (left image, left character) to synthesize

Faloutsos, Petros

81

An Error Driven Approach to Query Segmentation , Yunbo Cao  

E-print Network

the performance of state-of-the-art query segmentation methods on a publicly available data set. Categories Keywords Query Segmentation, Search Log Mining, Error Driven 1. INTRODUCTION Tokens (or wordsAn Error Driven Approach to Query Segmentation Wei Zhang§ , Yunbo Cao , Chin-Yew Lin , Jian Su

California at Berkeley, University of

82

INVESTIGATION OF PRODUCT-LAYER DIFFUSIVITY FOR CAO SULFATION  

EPA Science Inventory

The paper gives results of comparisons of the sulfation rates of CaO prepared from Ca(OH)2 and CaCO3, using six types of each precursor derived from the same natural limestones. The particles were small enough to eliminate all transport resistances except diffusion through the Ca...

83

On the development of two characteristically different crystal morphology in SiO(2)-MgO-Al (2)O (3)-K (2)O-B (2)O (3)-F glass-ceramic system.  

PubMed

The present work demonstrates how crystals with two different characteristic morphologies can be formed in SiO(2)-MgO-Al(2)O(3)-K(2)O-B(2)O(3)-F glass-ceramic system by adopting two sets of heat treatment experiments. In our study, single stage heat treatment experiments were performed at 1,000 degrees C for varying holding time of 8-24 h with 4 h time interval and as a function of temperature in the range of 1,000-1,120 degrees C with 40 degrees C temperature interval. The constant heating rate of 10 degrees C/min was employed for both sets of experiments. The microstructural changes were investigated using Fourier transformed infrared spectroscopy (FT-IR), SEM-EDS and XRD. For temperature variation batches, the microstructure is characterized by interlocked, randomly oriented mica plates ('house-of-cards' morphology). An important and new observation of complex crystal morphology is made in the samples heat treated at 1,000 degrees C for varying holding times. Such morphology appears to be the results of composite spherulitic-dendritic like growth of mica rods radiating from a central nucleus. The possible mechanism for such characteristic crystal growth morphology is discussed with reference to a nucleation-growth kinetics based model. The activation energy for crystal nucleation and Avrami index are computed to be 388 kJ/mol and 1.3 respectively, assuming Johnson-Mehl-Avrami model of crystallization. Another important result is that a maximum of around 70% of spherulitic-dendritic like crystal morphology can be obtained after heat treatment at 1,000 degrees C for 24 h, while a lower amount (approximately 58%) of interlocked plate like mica crystals is formed after heat treatment at 1,040 degrees C for 4 h. PMID:18704659

Roy, Shibayan; Basu, Bikramjit

2009-01-01

84

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

Microsoft Academic Search

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,

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

1995-01-01

85

Viscosity of many-component glasses  

SciTech Connect

The effect of composition on the viscosity of multicomponent glasses was expressed as a function of temperature and composition for three composition regions containing various subsets of Al2O3, B2O3, Bi2O3, CaO, Cr2O3, F, Fe2O3, K2O, Li2O, MgO, MnO, Na2O, NiO, P2O5, SiO2, UO2, and ZrO2. Limits of applicability of the composition models are discussed.

Hrma, Pavel R.; Arrigoni, Benjamin M.; Schweiger, Michael J.

2009-06-01

86

Partial molar volumes of oxide components in silicate liquids  

Microsoft Academic Search

Densities of 21 silicate liquids have been determined from 1,000 ° to 1,600 ° C. The compositions studied contain from two to eight oxide components and have the following ranges in composition (mole %): SiO2, 35–79%; TiO2, 4–36%; Al2O3, 5–25%; FeO, 11–41%; MgO, 7–28%; CaO, 7–35%; Na2O, 5–50%; and K2O, 4–20%. The compositions thus cover the upper range observed in

S. A. Nelson; I. S. E. Carmichael

1979-01-01

87

Luminescence properties of deformed CaO crystals  

SciTech Connect

In deformed CaO crystals, the predominant optical-absorption band at 270 nm and the corresponding luminescence band at 450 nm have been investigated. The absorption coefficient increases linearly with deformation up to [similar to]5% whereas the luminescence intensity saturates earlier. Thermal annealing indicates that appreciable decrease in the absorption begins at [similar to]600 K. In contrast, the luminescence intensity diminishes very rapidly at temperatures not much above room temperature. Time-resolved luminescence indicates that the 450-nm band is composed of two bands: a 475-nm band with lifetimes of [lt]3 ns and [similar to]10 [mu]s, and a 440-nm band with a lifetime of [similar to]1 ms at room temperature. In a test for laser action no optical gain was observed in a deformed CaO crystal.

Gonzalez, R. (Departamento de Ingenieria, Escuela Politecnica Superior, Universidad Carlos III, 28913 Leganes Madrid (Spain) Solid State Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6031 (United States)); Chen, Y.; Ballesteros, C. (Solid State Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6031 (United States)); Liu, H.; Williams, G.P. Jr.; Rosenblatt, G.H.; Williams, R.T. (Department of Physics, Wake Forest University, Winston-Salem, North Carolina 27109 (United States)); Gellermann, W. (Department of Physics, University of Utah, Salt Lake City, Utah 84112 (United States))

1993-03-01

88

DE LA CAO AUX CALCULS PAR LMENTS FINIS  

E-print Network

. . . . . . . . . . . . . . . . . . . . . . . 6 3 Applications au projet européen HIPPI 8 3.1 Passage de la CAO au CAST3M pour les cavités TRIPLE.4 Simulations mécaniques des cavités HIPPI sous pression . . . . . . . . . . . . . 13 3.4.1 Fixation d'accélérateurs internatio- naux, notamment, des projets européens comme HIPPI (High Intensity Pulsed Proton Injector

Paris-Sud XI, Université de

89

The Oxygenase CAO-1 of Neurospora crassa Is a Resveratrol Cleavage Enzyme  

PubMed Central

The genome of the ascomycete Neurospora crassa encodes CAO-1 and CAO-2, two members of the carotenoid cleavage oxygenase family that target double bonds in different substrates. Previous studies demonstrated the role of CAO-2 in cleaving the C40 carotene torulene, a key step in the synthesis of the C35 apocarotenoid pigment neurosporaxanthin. In this work, we investigated the activity of CAO-1, assuming that it may provide retinal, the chromophore of the NOP-1 rhodopsin, by cleaving ?-carotene. For this purpose, we tested CAO-1 activity with carotenoid substrates that were, however, not converted. In contrast and consistent with its sequence similarity to family members that act on stilbenes, CAO-1 cleaved the interphenyl C?-C? double bond of resveratrol and its derivative piceatannol. CAO-1 did not convert five other similar stilbenes, indicating a requirement for a minimal number of unmodified hydroxyl groups in the stilbene background. Confirming its biological function in converting stilbenes, adding resveratrol led to a pronounced increase in cao-1 mRNA levels, while light, a key regulator of carotenoid metabolism, did not alter them. Targeted ?cao-1 mutants were not impaired by the presence of resveratrol, a phytoalexin active against different fungi, which did not significantly affect the growth and development of wild-type Neurospora. However, under partial sorbose toxicity, the ?cao-1 colonies exhibited faster radial growth than control strains in the presence of resveratrol, suggesting a moderate toxic effect of resveratrol cleavage products. PMID:23893079

Díaz-Sánchez, Violeta; F. Estrada, Alejandro; Limón, M. Carmen; Al-Babili, Salim

2013-01-01

90

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

E-print Network

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

Chakhmouradian, Anton

91

Book Review: Tian Yu Cao, From Current Algebra to Quantum Chromodynamics: A Case  

E-print Network

Book Review: Tian Yu Cao, From Current Algebra to Quantum Chromodynamics: A Case for Structural of the International Society for the History of Philosophy of Science In this book, Tian Yu Cao chronicles the decade to the preface, the more philosophical companion piece to the historical book which will cover the longer period

Wüthrich, Christian

92

Efficient Top-K Query Calculation in Distributed Networks cao@theory.stanford.edu  

E-print Network

Efficient Top-K Query Calculation in Distributed Networks Pei Cao cao@theory.stanford.edu Zhe Wang This paper presents a new algorithm to answer top-k queries (e.g. "find the k objects with the highest ag) for data series following Zipf distribution. 1 Introduction We investigate algorithms that answer "top-k

Bejerano, Gill

93

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

PubMed

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

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

2015-03-23

94

Kinetic Study on Desulfurization of Hot Metal Using CaO and CaC2  

NASA Astrophysics Data System (ADS)

The kinetics and reaction mechanisms of hot metal desulfurization using CaO and CaC2 were studied in a well-controlled atmosphere with a lab scale high temperature furnace. The growths of CaS around CaO and CaC2 were measured and compared at 1773 K (1500 °C). The parabolic rate constant was evaluated to be 5 × 10-7 (cm s-1) on CaO particles, and 2.4 × 10-7 (cm s-1) on CaC2. The bigger parabolic constant of CaO resulted in more efficient desulfurization. Agglomerates and big CaO particles led to 2CaO·SiO2 formation which hindered further utilization of CaO for desulfurization. The 2CaO·SiO2 formation was favoured by a high oxygen potential. Since the desulfurization reaction of CaO not only produced CaS but also oxygen, the local oxygen concentration around big CaO particles was higher than around small particles.

Lindström, David; Sichen, Du

2015-02-01

95

Effect of H2O on the morphological changes of KNO3 formed on K2O/Al2O3 NOx storage materials: Fourier transform infra-red (FTIR) and time-resolved x-ray diffraction (TR-XRD) studies  

SciTech Connect

Based on combined FTIR and XRD studies, we report here that H2O induces a morphological change of KNO3 species formed on model K2O/Al2O3 NOx storage-reduction catalysts. Specifically as evidenced by FTIR, the contact of H2O with NO2 pre-adsorbed on K2O/Al2O3 promotes the transformation from bidentate (surface-like) KNO3 species to ionic (bulk-like) ones irrespective of K loadings. Once H2O is removed from the sample, a reversible transformation into bidentate KNO3 is observed, demonstrating a significant dependence of H2O on such morphological changes. TR-XRD results show the formation of two different types of bulk KNO3 phases (orthorhomobic and rhombohedral) in an as-impregnated sample. Once H2O begins to desorb above 400 K, the former is transformed into the latter, resulting in the existence of only the rhombohedral KNO3 phase. On the basis of consistent FTIR and TR-XRD results, we propose a model for the morphological changes of KNO3 species with respect to NO2 adsorption/desorption, H2O and/or heat treatments. Compared with the BaO/Al2O3 system, K2O/Al2O3 shows some similarities with respect to the formation of bulk nitrates upon H2O contact. However, there are significant differences that originate from the lower melting temperature of KNO3 relative to Ba(NO3)2.

Kim, Do Heui; Mudiyanselage, Kumudu K.; Szanyi, Janos; Hanson, Jonathan C.; Peden, Charles HF

2014-02-27

96

Secondary ionization coefficient ? of MgO, SrO and CaO and the correlation between ? and charge accumulated on CaO in argon  

NASA Astrophysics Data System (ADS)

An experimental investigation of Townsend's secondary ionization coefficient ? is carried out for MgO, SrO and CaO film electrodes. These oxides are utilized, or are to be utilized, in next-generation plasma display panels. All of the experiments are performed in argon. In particular, in the case of CaO film, our attention is attracted to the effect of charge accumulated on CaO film. For this purpose, the breakdown voltage Vs is observed from waveforms of the gap voltage and charge accumulated on the dielectric film electrodes with the repeated breakdown. Townsend's criterion is utilized to estimate ? from the breakdown voltage. In the case of the CaO film, ? increases gradually with repeated breakdowns and reaches a stationary value. The increase of ? is considered to be due to the charge that accumulates on the dielectric electrode triggering the next breakdown. Therefore, it is concluded that the increased ? is sustained by a combined process consisting of restarted electrons that have accumulated on the CaO film and the original ? action, as observed in metallic electrodes in a low-pressure gas discharge.

Suzuki, S.; Itoh, H.

2014-12-01

97

Primary origin of some trachytoid magmas: Inferences from naturally quenched glasses in hydrothermally metasomatized gabbroic xenoliths (Hyblean area, Sicily)  

NASA Astrophysics Data System (ADS)

Hydrothermally-modified gabbroic xenoliths from the Hyblean tuff-breccia deposits (Sicily) consist of albitized plagioclase, Fe-Mg-rich clays, aegirine-augite, ± zeolites, titanite, apatite, magnetite, and hydrothermal zircon. Pockets of silicate glass with perlitic cracking occur in some samples forming 15-20% (by volume) of the rock modal assemblage. Electron microprobe analyses show the trachytic composition of the glass, with generally peralkaline sodic affinity [molar Al 2O 3/(Na 2O + K 2O) ~ 0.8 (average value); molar Al 2O 3/(Na 2O + K 2O + CaO) ~ 0.7 (average value); Na 2O/K 2O (wt.%) = 1.7-2.3]. The glass trace element abundances, obtained by secondary ion mass spectrometry (SIMS) analyses are consistent with those of world-wide trachytes (e.g. Zr/Ti = 0.15-018; Nb/Y = 0.73-1). Relatively high abundances of Cl (700-1600 ppm) and F (> 500 ppm) were also detected in the glass. Careful macroscopic and microscopic observations exclude the possibility that external silicate melt infiltrated the xenolith. The occurrence of glass pockets between the mafic clay assemblages and the feldspar grains, along with comparisons between chemical compositions of the glass and the surrounding minerals, suggest that the glass is due to the melting of a eutectoid system consisting of Na-rich alkali feldspar, Fe-Mg-rich clays and aegirine-augite. Halogens had probably played an important role in the partial melting process by decreasing the melting temperature of modal minerals, especially feldspar. The occurrence of these trachytic glasses lends support to petrologic models suggesting that partial melting of a hydrothermally altered, brine-rich oceanic crust induced by shallow-seated basic intrusions can produce primary trachytoid melts. This may explain the "Daly-gap" characterizing some oceanic within-plate volcanoes.

Viccaro, Marco; Scribano, Vittorio; Cristofolini, Renato; Ottolini, Luisa; Manuella, Fabio C.

2009-12-01

98

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

99

[Investigation on bookstore block-printed editions of Zheng He Ben Cao in Ming Dynasty].  

PubMed

Many editions of Zheng He Ben Cao was published in Ming Dynasty. The bookstore block-printed editions recorded are Liu's Rixintang Edition in Zhengde year 14 (1519 AD), Yangxianchun Gui Renzai Edition and Jinling Tang's Fuchuntang Edition in Wanli year 6 (1578 AD). Rixintang Edition took Chenghua year 4 (1478 AD) Edition as source text and inherited the mistakes too. Guirenzai Version took Rixintang Version as source text, thereafter, Fuchuntang version took Guirenzai Version. Errors, missing, rough collation handed down from one version to another, thus in Fuchuntang Version, mistakes jumped out on each page. In order to attract more buyers, the bookstores erase the name Chong Xiu Zheng He Jing Shi Zheng Lei Bei Yong Ben Cao and change the name to Da Guan Ben Cao Gang Mu Quan Shu or Da Guan Ben Cao. PMID:21781550

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

2011-05-01

100

CAOS: a numerical simulation tool for astronomical adaptive optics (and beyond)  

NASA Astrophysics Data System (ADS)

We present recent developments of the CAOS "system", an IDL-based Problem Solving Environment (PSE) whose original aim was to define and simulate as realistically as possible the behavior of a generic adaptive optics (AO) system, from the atmospheric propagation of light, to the sensing of the wave-front aberratoins and the correction through a deformable mirror. The different developments made through the last 7 years result in a very versatile numerical tool complete of a global graphical interface (the CAOS Application Builder), and different specialized scientific packages: the original one designed for AO system simulations (the Software Package CAOS), an image reconstruction package with interferometric capabilities (the Software Package AIRY), and a more recent one being built and dedicated to multiconjugate AO (the Software Package MAOS). We present the status of the whole CAOS "system"/PSE, together with the most recent developments, including parallelization strategy considerations, examples of application, and plans for the next future.

Carbillet, Marcel; Verinaud, Christophe; Guarracino, Mario; Fini, Luca; Lardiere, Olivier; Le Roux, Brice; Puglisi, Alfio T.; Femenia, Bruno; Riccardi, Armando; Anconelli, Barbara; Correia, Serge; Bertero, Mario; Boccacci, Patrizia

2004-10-01

101

[Academic heritage of Jiu huang ben cao (Materia Medica for Relief of Famines) in Japan].  

PubMed

Jiu huang ben cao (Materia Medica for Relief of Famines) was the first monograph on famines herbal in the history of China, which creates a new research field of edible plants. Around the middle and late 17th century, Jiu huang ben cao was spread to Japan and aroused great attention of famous Japanese herbalists. Thus, all versions of different edition systems were circulated in Japan. Later, some famous Japanese scholar ssuccessively quoted texts of Jiu huang ben cao from the Nong zheng quan shu (Whole book on Agricultural Administration) spread in Japan, and block-printed it as an independent work. As a result, Jiu huang ben cao virtually circulated widely in Japan. PMID:25620360

He, Huiling; Xiao, Yongzhi

2014-11-01

102

Nonisothermal Thermogravimetric Analysis of Thai Lignite with High CaO Content  

PubMed Central

Thermal behaviors and combustion kinetics of Thai lignite with different SO3-free CaO contents were investigated. Nonisothermal thermogravimetric method was carried out under oxygen environment at heating rates of 10, 30, and 50°C min?1 from ambient up to 1300°C. Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods were adopted to estimate the apparent activation energy (E) for the thermal decomposition of these coals. Different thermal degradation behaviors were observed in lignites with low (14%) and high (42%) CaO content. Activation energy of the lignite combustion was found to vary with the conversion fraction. In comparison with the KAS method, higher E values were obtained by the FWO method for all conversions considered. High CaO lignite was observed to have higher activation energy than the low CaO coal. PMID:24250259

Pintana, Pakamon

2013-01-01

103

Dynamics of condensation in totally asymmetric inclusion process Jiarui Cao, Paul Chleboun and Stefan Grosskinsky  

E-print Network

Dynamics of condensation in totally asymmetric inclusion process Jiarui Cao, Paul Chleboun and Stefan Grosskinsky Mathematics Institute, The University of Warwick Introduction Totally asymmetric etc.) concentrate on a vanishing fraction of the volume. Recent studies show that diverse phenomena

Sengun, Mehmet Haluk

104

The activity of sodium oxide in molten float glass by EMF measurements  

Microsoft Academic Search

The Na2O activity in the molten float glass composed of 13.2m\\/o Na2O, 70.2m\\/o SiO2, 10.0m\\/o CaO, 5.9m\\/o MgO, etc. was determined in the temperature range from 1260 to 1380K by means of galvanic cells using Na–??-alumina as solid electrolyte. The Na2O activity, aNa2O, accompanying the reaction Na2O (dissolved in Na2O–WO3 melt)=Na2O (dissolved in molten glass) was found to be given

Woo-Sung Kim; Do-Hyung Cho; Sung-Ki Lim

2004-01-01

105

Kinetics of mixed rare earths minerals decomposed by CaO with NaCl-CaCl 2 melting salt  

Microsoft Academic Search

For increasing reaction rate and reducing decomposing temperature, TG-DTA, XRD, SEM and Chemical analysis were used to study the kinetics of mixed rare earths minerals decomposed by CaO with NaCl-CaCl2. The results showed that the reaction rate increased with increasing of NaC-CaCl2 addition, CaO addition, and decomposition temperature. The kinetics of mixed rare earths minerals decomposed by CaO conformed to

Xue BIAN; Jianli CHEN; Zhihua ZHAO; Shaohua YIN; Yao LUO; Fengyun ZHANG; Wenyuan WU

2010-01-01

106

Thermodynamic modeling of phase relations and metasomatism in shear zones  

NASA Astrophysics Data System (ADS)

Ductile shear zones have been recognized for a long time as privileged sites of intense fluid-rock interactions in the crust. In most cases they induce focused changes in mineralogy and bulk chemical composition (metasomatism) which in turn may control the deformation and fluid-migration processes. Therefore understanding these processes requires in a first step to be able to model phase relations in such open system. In this contribution, emphasizes in placed on metasomatic aspects of the problem. Indeed , in many ductile shear zones reported in metagranites, deformation and fluid-rock interactions are associated with gain in MgO and losses of CaO and Na2O (K2O is also a mobile component but it can be either gained or lost). Although the mineralogical consequences of this so-called Mg-metasomatism are well-documented (replacement of K-feldspar into phengite, breakdown of plagioclase into ab + ep, crystallization of chlorite), the origin of this coupled mass-transfer is still unknown. We have performed a forward modeling of phase relationships using petrogenetic grids and pseudosections that consider variations in chemical potential (?) of the mobile elements (MgO, CaO, Na2O). Chemical potential gradients being the driving force of mass transfer, ?-? diagrams are the most appropriate diagrams to model open systems where fluid-rock interactions are prominent. Chemical potential diagrams are equivalent to activity diagrams but our approach differs from previous work because (1) solid solutions are taken into account (2) phase relations are modeled in a more realistic chemical system (Na2O-CaO-K2O-FeO-MgO-Al2O3-SiO2-H2O) and (3) the use of pseudosections allows to predict changes of the mineralogy (modes, composition) for the specific bulk composition studied. A particular attention is paid to the relationships between component concentrations and chemical potentials, which is not obvious in multi-component system. The studied shear zone is located in the Grimsel granodiorite (Swiss Alps). Fourteen samples have been taken along a 80 meter-wide strain gradient from the undeformed granodiorite protolith to the ultramylonitic zone. The metastable magmatic assemblage consists of oligoclase (50 vol%), quartz ( 20 vol%), K-feldspar (17 vol%), and biotite (13 %). With increasing strain, K-feldspar and oligoclase rapidly disappear to produce albite and epidote porphyroblast (up to 45 and 5 vol% respectively) with phengite in shear planes (15 vol%). In the mylonite and ultramylonite, magmatic phases have been completely recrystallized and the metamorphic albite volume decreases down to 25 vol% whereas phengite constitutes up to 30 vol% of the rock. Epidote is absent in the ultramylonite. In localized shear bands, the metamorphic assemblage consists of phengite, chlorite, biotite and quartz. Mass balance calculations show that the ultramylonite is enriched in MgO (up to 130%) while CaO and Na2O are remove (80% and 45% respectively). However, mass transfer is even stronger in the chlorite-bearing shear bands, where CaO and Na2O have been completely leached out. Chemical potential pseudosections are constructed using the bulk composition of the unaltered granodiorite, with K2O, FeO, Al2O3 and SiO2 content remaining constant. Deformation occurred under water-saturated conditions at 6 kbar and 450°C. MgO, CaO and Na2O are considered as "perfectly mobile" components and therefore their chemical potentials, which is fixed by the externally-derived fluid, control the stability of the phases. ?MgO vs ?CaO and ?MgO vs ?Na2O diagrams, show that the breakdown of a Kf-ab-ep assemblage into phengite and the subsequent crystallization of chlorite require the introduction of a fluid with a ?CaO and ?Na2O significantly lower than in the unaltered metamorphic assemblage (Kf-ab-ep-Kf-Bio-q). Equalizing the chemical potential gradient of CaO and Na2O, established between the fluid and the metamorphic assemblage, is achieved by the complete removal of CaO and Na2O. The most striking result is that chemical potential diagram predicts

Goncalves, P.; Oliot, E.; Marquer, D.

2009-04-01

107

Structural studies of mixed glass former 0.35Na2O + 0.65[xB2O3 + (1 - x)P2O5] glasses by Raman and 11B and 31P magic angle spinning nuclear magnetic resonance spectroscopies.  

PubMed

The mixed glass former (MGF) effect (MGFE) is defined as a nonlinear and nonadditive change in the ionic conductivity with changing glass former composition at constant modifier composition. In this study, sodium borophosphate 0.35Na(2)O + 0.65[xB(2)O(3) + (1 - x)P(2)O(5)], 0 ? x ? 1, glasses which have been shown to exhibit a positive MGFE have been prepared and examined using Raman and (11)B and (31)P magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopies. Through examination of the short-range order (SRO) structures found in the ternary glasses, it was determined that the minority glass former, B for 0.1 ? x ? 0.7 and P for 0.7 ? x ? 0.9, is "overmodified" and contains more Na(+) ions than would be expected from simple linear mixing of the binary sodium borate, x = 1, and sodium phosphate, x = 0, glasses, respectively. Changes in the intermediate range order (IRO) structures were suggested by changes in the NMR spectral chemical shifts and Raman spectra wavenumber shifts over the full composition range x in the Raman and MAS NMR spectra. The changes observed in the chemical shifts of (31)P MAS NMR spectra with x are found to be too large to be caused solely by changing sodium modification of the phosphate SRO structural groups, and this indicates that internetwork bonding between phosphorus and boron through bridging oxygens (BOs), P-O-B, must be a major contributor to the IRO structure of these glasses. While not fully developed, a first-order thermodynamic analysis based upon the Gibbs free energies of formation of the various SRO structural units in this system has been developed and can be used to account for the preferential formation of tetrahedral boron groups, B(4), by the reaction of B(3) with P(2) groups to form B(4) and P(3) groups, respectively, where the superscript denotes the number of BOs on these units, in these glasses. This preference for B(4) units appears to be a predominate cause of the changing modifier to glass former ratio with composition x in these ternary MGF glasses and appears to be associated with the large negative value of the Gibbs free energy of formation of this group. PMID:23281937

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

2013-02-21

108

ULTRASONIC DETERMINATION OF ELASTIC MODULUS OF MARBLES RELATION WITH POROSITY AND CaO %  

E-print Network

Since ancient Greek times marble has been used for decoration and for sculpture. In this paper, we have analyzed marble samples, which were selected according to their porosity and the proportion of CaO values, with ultrasonic velocity measurement methods. Elastic modulus was evaluated from longitudinal and transverse velocity of ultrasonic wave propagation in marble samples. Our results indicate that the elastic modulus shows linear dependence to the porosity and the proportion of CaO. The correlation factor of fitted line is about 0.9. Also the longitudinal velocity shows more linearity than the transverse velocity.

H. Sarpün; V. Özkan; S. Tuncel

109

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

E-print Network

Thermodynamics of strained vanadium dioxide single crystals Yijia Gu, Jinbo Cao, Junqiao Wu;Thermodynamics of strained vanadium dioxide single crystals Yijia Gu,1,a Jinbo Cao,2 Junqiao Wu,2 and Long Vanadium dioxide undergoes a metal­insulator transition, in which the strain condition plays an important

Chen, Long-Qing

110

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

111

ANNUAL TREE GROWTH PREDICTIONS FROM PERIODIC MEASUREMENTS Quang V. Cao1  

E-print Network

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

Cao, Quang V.

112

PERSPECTIVES Hu and Cao 179 6. United Nations Environment Programme. Inte-  

E-print Network

- vere water scarcity. Some experts believe that the water crisis may come before an energy crisis Advance access publication 14 May 2014 MULTIDISCIPLINARY Water science on the molecular scale: new insights into the characteristics of water Jun Hu1, and Zexian Cao2 The highest good is like that of water

Zexian, Cao

113

3D Fingerprint Phantoms Sunpreet S. Arora, Kai Cao and Anil K. Jain  

E-print Network

) printing the 3D fingerprint phantoms using a commodity 3D printer. Preliminary experimental results show3D Fingerprint Phantoms Sunpreet S. Arora, Kai Cao and Anil K. Jain Department of Computer Science, we propose creating 3D fin- gerprint phantoms (phantoms or imaging phantoms are specially designed

114

Stem Cell Repair of Central Nervous System Qilin Cao,1,2  

E-print Network

and Brundin, 1988; Hoffer and Olson, 1991). The use of neural stem cells (NSCs) as a source of multipotentReview Stem Cell Repair of Central Nervous System Injury Qilin Cao,1,2 Richard L. Benton,1 of Louisville School of Medicine, Louisville, Kentucky Neural stem cells (NSCs) have great potential as a ther

Harkema, Susan

115

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

E-print Network

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

Wu, Junqiao

116

Evaluation of Methods for Calibrating a Tree Taper Quang V. Cao and Jing Wang  

E-print Network

biometrics Evaluation of Methods for Calibrating a Tree Taper Equation Quang V. Cao and Jing Wang quantiles performed slightly better than the other calibration methods, based on two evaluation statistics calibration methods were investigated, including the use of fixed- and mixed-effects models, as well

Cao, Quang V.

117

A Model of Stroke Extraction from Chinese Character Images Ruini Cao, Chew Lim Tan  

E-print Network

A Model of Stroke Extraction from Chinese Character Images Ruini Cao, Chew Lim Tan School a new model of stroke extraction for Chinese characters. One problem for stroke extraction is how to extract primary strokes. Another major problem is to solve the segmentation ambiguities at intersection

Tan, Chew Lim

118

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

E-print Network

Ubiquitous Intelligence in Agent Mining Longbing Cao, Dan Luo, and Chengqi Zhang Faculty, most of them can be described in terms of or related to ubiquitous intelligence. It is certainly very important to define, specify, represent, analyze and utilize ubiquitous intelligence in agents, data mining

Cao, Longbing

119

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

E-print Network

the sensor network, which means that the relocation should minimize its effect on the current sensingSensor 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

Zhang, Wensheng

120

www.cell-research.com | Cell Research Qi Cao et al.  

E-print Network

www.cell-research.com | Cell Research Qi Cao et al. 671 npg ORIGINAL ARTICLE Glycogen synthase cancer cells, implicating this kinase as a potential therapeutic target in ovarian cancer. Cell Research sensitizes hepatoma cells to chemotherapy-induced apoptosis [4]. GSK-3 is an evolutionarily conserved

Cai, Long

121

IDENTIFICATION OF CASO4 FORMED BY REACTION OF CAO AND SO2  

EPA Science Inventory

The article discusses the XRD-determination of the identity of CaSO4, formed by the reaction between CaO and S02, and the support of that determination by density measurements with helium pycnometry. The anhydrous CaS04 compound formed has an orthorhombic crystal structure and an...

122

METHOD FOR VARIATION OF GRAIN SIZE IN STUDIES OF GAS-SOLID REACTIONS INVOLVING CAO  

EPA Science Inventory

The paper describes a method for varying grain size in studies of gas-solid reactions involving CaO. (Note: Introducing grain size as an independent experimental variable should contribute to improved understanding of reactions in porous solids.) Calcining 1 micrometer CaCO3 part...

123

EFFECT OF SPECIFIC SURFACE AREA ON THE REACTIVITY OF CAO WITH SO2  

EPA Science Inventory

The paper discusses results of measuring the rate of reaction of calcined limestone (CaCO3) with sulfur dioxide (SO2) and oxygen (O2) at conditions that eliminate all resistances not associated with the lime (CaO) grain surface. Reactivity increased with the square of the Brunaue...

124

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

125

Semimicro chemical and x-ray fluorescence analysis of lunar samples  

USGS Publications Warehouse

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).

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

126

Volatile fractionation and tektite source material  

NASA Technical Reports Server (NTRS)

The arguments used by Love and Woronow (1988) to assess the role played in the origin of bediasites by extensive volatile fractionation are critically examined. Using the ratios of 'refractory' oxides, CaO, Al2O3, and MgO, to the 'volatile' oxides, Na2O and K2O, these authors concluded that vapor fractionation did not play a significant role. In this paper, experimental evidence is presented that shows that the assumption of volatility for the alkali elements (as least with respect to silica) to be not valid under the conditions under which tektites formed. It is shown that the results of vapor fractionation in experiments on glasses of tektite composition are approximately parallel the trends seen in bediasite analysis.

Walter, Louis S.

1989-01-01

127

Major and trace elements in igneous rocks from Apollo 15.  

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

128

GEMAS: Distribution of major elements in Polish agricultural soil  

NASA Astrophysics Data System (ADS)

Amount and quality of produced food is highly dependent on soil chemical properties and composition. The GEMAS project (Geochemical Mapping of Agricultural and Grazing Land Soil of Europe) has provided new homogeneous geochemical data for Polish agricultural soils. This study presents the distribution of common major elements such as CaO, MgO, Fe2O3, Al2O3, K2O, Na2O, SiO2, determined in 129 samples of agricultural soil of Poland. The total element concentrations obtained by X-ray fluorescence spectroscopy (XRF) were compared with the results from aqua regia acid digestion determined by ICP-MS. The distribution patterns of selected major elements reveal two major geochemical provinces - the northern province and the southern province, distinguished with respect to the natural geochemical background and resulting from the geological evolution of the region. The soil of the northern province (Polish Lowland), dominated by glacial deposits, show low contents of CaO, MgO, Fe2O3, Al2O3, K2O, Na2O, and high contents of SiO2. High silica content reflects the presence of sand-rich deposits which belong to the larger European feature with cover sands and loess of mainly Weichselian age and stretching from Ukraine to western Germany and Denmark. The southern province is characterised by high concentrations of almost all major elements (except SiO2). Soils in the Sudetes, Upper Silesia and the Carpathian Mountains developed in majority on pre-Quaternary rocks. In the Sudetes, soil formed on magmatic and metamorphic rocks of Paleozoic age. In the Carpathians and Upper Silesia, the flysch and molasse formations containing various material of magmatic and sedimentary origin constitute the immediate substratum of soil.

Dusza-Dobek, Aleksandra; Pasieczna, Anna; Kwecko, Pawe?

2014-05-01

129

Comparison between the in vitro surface transformations of AP40 and RKKP bioactive glasses.  

PubMed

Two bioactive silica-phosphate glasses, AP40 and RKKP, were compared in their behaviour in simulated biological environment. Their chemical composition is practically identical, except that RKKP contains small amounts of amphoteric network-former oxides Ta2O5 and La2O3 (composition in wt% for AP40: beta-Ca3(PO4)2 24.50, SiO2 44.30, CaO 18.60, Na2O 4.60, K2O 0.19, MgO 2.82, CaF2 4.99; RKKP: beta-Ca3(PO4)2 24.23, SiO2 43.82, CaO 18.40, Na2O 4.55, K2O 0.19, MgO 2.79, CaF2 4.94, Ta2O5 0.99, La2O3 0.09). Previous investigations showed a better performance in osteopenic bone for RKKP. To gain more insight into these differences in biological behaviour, the in vitro bioactivity of the glasses was studied by treatment with a continuously replenished Hanks' Balanced Salt Solution (HBSS). The glasses were examined before and after HBSS treatment for 20 and 40 days by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Energy Dispersion (EDX), Raman and IR vibrational spectroscopies. Some slight but notable differences between the two glasses were observed after HBSS treatment. IR and EDX analyses showed that deposits formed on both glasses were composed of a calcium deficient carbonate-apatite; however, the layer formed on RKKP glass was found to be slightly more calcium deficient and thinner. EDX analysis evidenced the presence of a small percentage of F- ions only in the layers formed on the RKKP samples. The differences disclosed, although slight, can contribute to the understanding of the different biological behaviour previously observed. PMID:15744599

Krajewski, A; Ravaglioli, A; Tinti, A; Taddei, P; Mazzocchi, M; Martinetti, R; Fagnano, C; Fini, M

2005-02-01

130

[Textual research on Costus root (Aucklandia lappa Decne) in the Sheng nong ben cao jing (Shennong's Classic of Materia Medica)].  

PubMed

Aucklandia lappa Decne was first recorded in the Sheng nong ben cao jing (Shennong's Classic of Materia Medica). Through the textual research of herbal literature, it was found that the costus root in the Sheng nong ben cao jing perhaps was not the plant of Aucklandia lappa Decne of Compositae, but the eaglewood or Lignum Aquilasria Resinatum based on the comprehensive judgment of shape, taste, nature, and function etc. In the Sheng nong ben cao jing, it only includes costus root without the title of eaglewood, and Tao Hongjing recorded both herbs together in his Ming yi bie lu (Supplementary Records of Celebrated Physicians), which became a foreshadow of misunderstanding of the later generations. Beginning from the Tang ben cao (Materia Medica of the Tang Dynasty), the costus root was considered as the plant of Auckiandia lappa Decne from the Compostae with its profound influence until now. PMID:25208833

Li, Guangyan; Wang, Dequn; Fang, Shiying; Xu, Maohong

2014-05-01

131

Characterization of CaO+ and BaO+ by Two-Photon Ionization Spectroscopy  

NASA Astrophysics Data System (ADS)

Reactions of laser-cooled Ca+ and Ba+ ions with O2 provide pathways to the formation of cold molecular cations (CaO+ and BaO+) that may be further manipulated using ion trapping techniques. Spectroscopic data for these ions are needed to facilitate the characterization of internal state population distributions using highly sensitive detection schemes such as resonantly enhanced multi-photon dissociation (REMPD). Ab initio electronic structure calculations predict that both ions have X1?+ ground states, accompanied by low-lying A2? states. We are currently using two-color photoionization techniques to observe the low-lying ro-vibronic states of CaO+ and BaO+. The neutral molecules are produced by laser ablation of the metals, combined with free-jet expansion driven by He/O2 (0.1-0.2%) mixtures. Photoionization efficiency curves and zero kinetic energy photoelectron spectra will be reported.

Bartlett, Joshua; VanGundy, Robert A.; Heaven, Michael

2014-06-01

132

Treatability of PCB-contaminated soils with quicklime (CaO)  

Microsoft Academic Search

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

D. Mauro; B. B. Taylor

1992-01-01

133

Thermal diffusivity of sintered 12CaO×7Al2O3  

NASA Astrophysics Data System (ADS)

The thermal diffusivity and free carrier diffusion coefficient of 12CaO× 7 Al{2}O{3} (C12A7) sintered for different times in air or hydrogen followed by treatment with UV light were determined from photoacoustic phase and amplitude spectra obtained using the photoacoustic method with a transmission detection configuration. The influence of the sintering time on the values of the obtained parameters was analyzed and also the different sintering procedures.

Nikoli?, P. M.; Lukovi?, D. T.; Savi?, S. M.; Milovanovi?, A. M.; Uki?, S. R.; Nikoli?, M. V.; Stamenovi?, B.

2008-01-01

134

Porous carbon material containing CaO for acidic gas capture: preparation and properties.  

PubMed

A one-step process for the preparation of CaO-containing porous carbons is described. Mixtures of poly(ethylene terephthalate) with natural limestone were pyrolyzed and thus hybrid sorbents could be easily obtained. The polymeric material and the mineral served as a carbon precursor and CaO delivering agent, respectively. We discuss effects of the preparation conditions and the relative amounts of the raw materials used for the preparations on the porosity of the hybrid products. The micropore areas and volumes of the obtained products tended to decrease with increasing CaO contents. Increase in the preparation temperature entailed a decrease in the micropore volume, whereas the mesopore volume increased. The pore creation mechanism is proposed on the basis of thermogravimetric and temperature-programmed desorption measurements. The prepared CaO-containing porous carbons efficiently captured SO2 and CO2 from air. Washing out of CaO from the hybrid materials was confirmed as a suitable method to obtain highly porous carbon materials. PMID:23743266

Przepiórski, Jacek; Czy?ewski, Adam; Pietrzak, Robert; Toyoda, Masahiro; Morawski, Antoni W

2013-12-15

135

Interaction of CO with CaO surfaces: A TPD and FTIR study  

NASA Astrophysics Data System (ADS)

By using temperature-programmed desorption (TPD) gas analysis, thermal desorptions of C 16O and C 18O were observed at peak temperatures of 460 and 430 K, respectively, after C 18O exposure at room temperature on CaO powders. By using FTIR measurements, C 16O adsorption produced main IR bands at 1606 and 1316 cm -1 (assigned to carbonate-type species), which disappeared after heating up to 500 K under condition of high vacuum. Oxygen exchange between C 18O and Ca 16O may occur through a CO 3-type intermediate on the surfaces, involving a lattice oxygen to produce the C 16O TD peak.

Yanagisawa, Yasunori; Kashima, Shin-ichi

2000-05-01

136

Microporous crystal 12CaO x 7Al(2)O(3) encaging abundant O(-) radicals.  

PubMed

Extremely high concentrations (>1020 cm-3) of active oxygenic radicals, O- and O2-, have been created in the zeolitic crystal, 12CaO.7Al2O3 (C12A7), which can accommodate anions in its cavities. An increase in oxygen pressure and a decrease in water vapor pressure at high temperature enhance the formation of the radicals. The oxidation of Pt is observed on the surface of the material as a result of reaction with the active oxygens. PMID:11817934

Hayashi, Katsuro; Hirano, Masahiro; Matsuishi, Satoru; Hosono, Hideo

2002-02-01

137

Nb-doped CaO: an efficient electron donor system  

NASA Astrophysics Data System (ADS)

Transition metal atoms incorporated into insulating materials (oxides in particular) can deeply modify their adsorption properties. In particular, charge transfer to adsorbed species can be induced by the presence of substitutional dopants, which introduce new electronic states in the band gap of the host crystal. Here we show, by means of density functional theory calculations, that Nb represents an excellent dopant to turn the rather inactive CaO(100) surface into an electron-rich support. The charge transfer ability of the doped material is shown by comparing the adsorption properties of the electronegative Au atoms on pure and Nb-doped CaO. While in the first case the CaO-Au bonding is relatively weak and the Au atom is essentially neutral, in the Nb-doped system a much stronger adhesion is found due to a net charge transfer from the Nb dopant and to the formation of a gold anion. This mechanism occurs also for Nb in high oxidation states. Nb is thus an excellent modifier of the calcium oxide properties.

Prada, Stefano; Giordano, Livia; Pacchioni, Gianfranco

2014-08-01

138

Impacts of the 2010 Amazon drought on forest structure and function using CAO AToMS  

NASA Astrophysics Data System (ADS)

The 2010 Amazon mega-drought is thought to have had a widespread impact on forest condition, including tree mortality. However, no large-scale, high-resolution information exists on changes in forest structure, function, turnover or other processes in response to the drought. With the possibility of increasing drought frequency in the Amazon basin, it is now critical that we develop repeat, large-area studies to assess impacts and recovery. Using the Carnegie Airborne Observatory Airborne Taxonomic Mapping System (AToMS), we assessed the impacts of the 2010 drought by repeat flying of approximately 500,000 hectares of lowland humid tropical forest in the Peru Amazon. The CAO AToMS Visible-to-Near-Infrared (VNIR) and Visible-to-Shortwave-Infrared (VSWIR) imaging spectrometers recorded changes in forest canopy spectral, chemical and physiological state from 2009 to 2011. Areas of greatest functional change were observed near the Peru-Brazil border in areas under heavy forest use for selective logging. The CAO AToMS waveform Light Detection and Ranging (LiDAR) instruments measured highest rates of treefall and canopy gap formation in areas subjected to combined drought and logging, and on low fertility soils. The results provide the first spatially-explicit, large-scale and ecologically detailed information on the response of Amazonian forests to drought.

Asner, G. P.; Martin, R. E.; Knapp, D. E.; Kennedy-Bowdoin, T.; Kellner, J.

2012-12-01

139

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

SciTech Connect

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.

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

1994-11-01

140

Engineering nanostructured electrodes away from equilibrium for lithium-ion Yanyi Liu, Dawei Liu, Qifeng Zhang and Guozhong Cao*  

E-print Network

, University of Washington, Seattle, WA, 98195, USA Yanyi Liu Yanyi Liu is a Ph.D. student underEngineering nanostructured electrodes away from equilibrium for lithium-ion batteries Yanyi Liu, Dawei Liu, Qifeng Zhang and Guozhong Cao* Received 5th December 2010, Accepted 15th February 2011 DOI

Cao, Guozhong

141

QUANTITATIVE RELAXATION TEMPLATES FOR THE HUMAN BRAIN AT 3T Fang Cao, Olivier Commowick, Camille Maumet, Christian Barillot  

E-print Network

QUANTITATIVE RELAXATION TEMPLATES FOR THE HUMAN BRAIN AT 3T Fang Cao, Olivier Commowick, Camille, T2, T 2 and maps from the human brain at 3T. The qMRI templates were built from a population of 20 of the human brain do not include quantitative features of the human brain such as those extracted from

Paris-Sud XI, Université de

142

First-principles and experimental characterization of the electronic and optical properties of CaS and CaO  

NASA Astrophysics Data System (ADS)

Doped alkaline-earth chalcogenides are interesting photoluminescent materials for opto-electronic applications. It is crucial to have an extended knowledge about the undoped bulk CaS and CaO since all the excited state properties of the doped material heavily depend on it. In this work we investigate the structural parameters, electronic band structures, macroscopic dielectric constants and absorption spectra for CaS and CaO compounds. Their quasi-particle band structure in the GW approximation yields a value of 4.28 eV and 6.02 eV for the indirect theoretical particle gap of CaS and CaO, respectively. The imaginary part of the macroscopic dielectric function ?(?) is computed including excitonic effects through the Bethe-Salpeter equation. The onset of absorption is within 0.1 eV of the experimental one and the calculated spectrum shows a qualitative agreement with experiment. Our computed exciton binding energies are 0.27 eV and 0.40 eV for CaS and CaO, respectively.

Poncé, S.; Bertrand, B.; Smet, P. F.; Poelman, D.; Mikami, M.; Gonze, X.

2013-05-01

143

Superconductivity in Iron Telluride Thin Films under Tensile Stress L. X. Cao,1,* X. Y. Wang,2  

E-print Network

Superconductivity in Iron Telluride Thin Films under Tensile Stress Y. Han,1 W. Y. Li,1 L. X. Cao,1 for Superconductivity, Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese a tensile stress state, superconductivity of 13 K was introduced into FeTe, a nonsuperconducting parent

Wang, Wei Hua

144

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

145

Max-min Fairness in 802.11 Mesh Networks Douglas J. Leith, Qizhi Cao, Vijay G. Subramanian  

E-print Network

1 Max-min Fairness in 802.11 Mesh Networks Douglas J. Leith, Qizhi Cao, Vijay G. Subramanian fairness methods to be generalised to this class of networks. This creates a solid theoretical underpinning for fairness analysis and resource allocation in this practically important class of networks. For the special

Kuzmanovic, Aleksandar

146

Indexing DNA Sequences Using q-grams Xia Cao, Shuai Cheng Li, and Anthony K. H. Tung  

E-print Network

Indexing DNA Sequences Using q-grams Xia Cao, Shuai Cheng Li, and Anthony K. H. Tung {caoxia to the interest, this paper presents a method for indexing the DNA sequences efficiently based on q. Two level index ­ hash table and c-trees ­ are proposed based on the q-grams of DNA sequences

Tung, Anthony Kum Hoe

147

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

E-print Network

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

Sun, Dengfeng

148

Luminescence of F sup + centers in CaO crystals under pulsed-laser excitation  

SciTech Connect

Luminescence of {ital F}{sup +} centers (oxygen vacancies each with one electron) has been investigated in thermochemically reduced, electron-irradiated, and neutron-irradiated CaO crystals. Time-dependent emission spectra following laser excitation into the {ital F}{sup +} absorption band at 351 nm were measured for the three types of crystals. We observed a fast component with a lifetime {le}10 ns and a slow decay attributed to charge trapping and transport. The intensity and decay kinetics of the {ital F}{sup +} phosphorescence depended on the method by which the defects had been produced. Estimated gain coefficients for stimulated emission under pulsed laser pumping are less than 0.1 cm{sup {minus}1}. These values are significantly smaller than the absorption coefficient at the emission wavelength.

Park, J.L.; Chen, Y. (Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6031 (USA)); Williams, G.P. Jr.; Williams, R.T. (Department of Physics, Wake Forest University, Winston-Salem, North Carolina 27109-7507 (USA)); Pogatshnik, G.J. (Department of Physics, Southern Illinois University, Edwardsville, Illinois 62026-1654 (USA))

1991-05-15

149

Impacts of quicklime (CaO) on the toxicity of copper (CuSO4, 5H2O) to fish and fish food organisms.  

PubMed

Static bioassays of 96 h duration were conducted in the laboratory using fry of common carp (Cyprinus carpio), adult tubificid worm (Branchiura sowerbyi) and adult copepod plankton (Cyclops viridis) to determine LC50 values of Cu and CaO to these organisms and effects of interaction between Cu and CaO. Ninety-six hour LC(50) values of Cu to fry of common carp, worm and copepod were found to be 1.40 mgl(-1), 0.08 mgl(-1) and 0.03 mgl(-1) respectively. CaO up to 500 mgl(-1) did not produce any mortality of the fry of common carp up to 96 h. But 96 h LC50 values of CaO to worm and copepod were 83.00 mgl(-1) and 27.80 mgl(-1) respectively. When common carp fry, worm and the copepod were exposed to respective LC50 dose of Cu in presence of varying concentration of CaO, mortality of the organisms significantly reduced and was found inversely correlated with the doses of CaO [y = 48.36-0.807x, r = -0.99 (n = 7) for fish; y = 44.46-0.146x, r = -0.97 (n = 7) for worm; y = 49.46-0.66x, r = -0.99 (n = 7) for the copepod]. The present results indicate that CaO is non-toxic to fish and is capable of reducing the toxicity of Cu to fish while CaO and Cu are antagonistic to each other for the worm and the copepod. Potential of using CaO as antitoxic agent for Cu in water is discussed. PMID:16168741

Das, Bipul Kumar; Das, Nina

2005-10-01

150

The ultrapotassic rocks: Characteristics, classification, and constraints for petrogenetic models  

NASA Astrophysics Data System (ADS)

A definition for ultrapotassic rocks is introduced using the chemical screens K 2O > 3 wt.%, MgO > 3 wt.% and K 2O/Na 2O > 2 for whole-rock analyses. On this basis a data base of more than 800 analyses was retrieved by a literature review. These are grouped according to a 'resemblance' classification designed to aid petrogenetic modelling by by-passing mineralogically based nomenclature groupings. Three major chemical end-member groups are recognised: Group I, lamproites, characterised by low CaO, Al 2O 2 and Na 2O, and high K 2O/Al 2O 3 and Mg-number. Group I rocks have the highest 'trace' incompatible element contents, and carry mostly depleted dunite and harzburgite mantle xenoliths. West Kimberley and Gaussberg are chosen as the standard members. Group I rocks usually have no associated non-ultrapotassic rocks, but non-standard members have calc-alkaline and shoshonitic associates, may occur in orogenic areas, and frequently have some chemical characteristics which are transitional to those of group III. Group II, known as kamafugites, have Toro Ankole rocks as their standard members. They have low SiO 2 and high CaO. Incompatible elements are less enriched than group I, but have a positive Sr spike. Group III rocks occur in orogenic areas and have high CaO and Al 2O 3. Mg-number is often low due to fractional crystallisation, but primary magmas have many of the characteristics of mantle derivation. Partial melting of mantle material previously enriched in incompatible elements is considered the most likely explanation for the origin of primary magmas for all three groups. Processes in the mantle before enrichment, during the enrichment event, and during partial melting at the magma genesis stage are considered separately for their likely effect on magma characteristics defined by the data base. Group I rocks probably originate from a depleted mantle under H 2O- and F-rich, CO 2-poor and possibly CH 4-rich conditions. The range in silica contents of primary lamproitic magmas may be due to partial melting at variable depth, with the diamond-bearing olivine lamproites originating from the greatest depth. The low SiO 2, high CaO and Sr of group II rocks suggests melting in a CO 2-rich, H 2O-poor environment, which is also indicated by CO 2-rich volcanic gases. The source for Toro Ankole lavas may originally have been depleted, but evidence from nodules is lost due to pervasive metasomatism. Group III rocks occur in orogenic areas, and many of their chemical characteristics must be explained by similar processes to those in less alkaline island-arc magmatism. The low Ti, Nb and Ba may be due to titanate phases being stable in the residue during partial melting, or to reactions in the subducted slab. High K 2O may be derived from subducted crustal material or from mantle enrichment occurring beneath the maturing arc, but unrelated to the subducted slab. High CaO and Al 2O 3 are favoured by melting a fertile mantle source. A fourth, transitional group includes both rocks which are likely to be mantle-derived and those which may be cumulates from crustal melts. A number of minettes may be due to crustal modification of mantle-derived potassic magmas.

Foley, S. F.; Venturelli, G.; Green, D. H.; Toscani, L.

1987-04-01

151

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

NASA Astrophysics Data System (ADS)

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.

Féret, J.; Asner, G. P.

2012-12-01

152

Tephra record from the Sea of Marmara for the last 70 ka and its paleoceanographic implications  

NASA Astrophysics Data System (ADS)

Sea of Marmara (SoM) is a gateway between the Mediterraean and Black seas, and a tectonically active basin located on a transform plate boundary. Tephra record in the SoM is therefore very important for dating palaeoceanographic, paleoclimatic and tectonic events. We report three tephra units in cores from the SoM extending back to ca 70 ka BP and including an upper marine and a lower lacustrine units separated by a 12 ka (uncalib.) boundary. The uppermost tephra unit is up to 8 mm thick layer in the marine unit. It is heterogenous phonolitic with high total alkali content of 12.4-15.7 wt % and K2O/Na2O of 0.9 to 1.2. The middle and lower tephra layers occur in the lacustrine unit in ca 29 m-long Core MD-01-2430. The middle tephra (MT-1) is a 70 mm-thick homogeneously rhyolitic layer. The lower tephra (MT-2) is 140 mm thick and has a phonolitic-trachytic composition with CaO content of 1.7-1.9 wt % and bimodal K2O/Na2O of 1.0-1.4. Using their geochemical composition and stratigraphic analysis, we assign the tephra units, from top to bottom, to Vesuvius AP2 Pumice, Santorini Cape Riva and Campanian Ignimbrite, which have been previously dated at 3.5 ka BP, 21.95 ka BP, and 39.3 ka BP (all calender ka). The continuous sedimentary record in the Core MD-01-2430 covering the last ca 70 ka indicates that the SoM was lacustrine, disconnected from the Mediterraean Sea during MIS4, MIS3 and most of MIS2. This implies that the sill depth of the Çanakkale Strait (Dardanelles) was shallower than the present-day -65 m sill depth during MIS3 and MIS4. Figure 1: Morphotectonic map of the Sea of Marmara showing location of the studied cores (red stars). Figure 2: Geochemical biplots of tephra glass composition. a) Total alkali silica diagram b) FeO versus total alkalies for allocating cryptotephras from core MNTKS34 and ML01 to the AP2 tephra from Vesuvius. c) FeO versus CaO for correlating tephra MT1 with the Y-2 tephra from Santorini. d) SiO2 versus CaO for discriminating the MT2 tephra (Campanian Ignimbrite).

Cagatay, M.; Wulf, S.; Guichard, F.; Ozmaral, A.; Sancar; Akçer-Ön, S.; Henry, P.; Gasperini, L.

2013-12-01

153

Biodiesel production from transesterification of palm oil with methanol over CaO supported on bimodal meso-macroporous silica catalyst.  

PubMed

Calcium oxide-loaded porous materials have shown promise as catalysts in transesterification. However, the slow diffusion of bulky triglycerides through the pores limited the activity of calcium oxide (CaO). In this work, bimodal meso-macroporous silica was used as a support to enhance the accessibility of the CaO dispersed inside the pores. Unimodal porous silica having the identical mesopore diameter was employed for the purpose of comparison. Effects of CaO content and catalyst pellet size on the yield of fatty acid methyl esters (FAME) were investigated. The basic strength was found to increase with increasing the CaO content. The CaO-loaded bimodal porous silica catalyst with the pellet size of 325?m achieved a high %FAME of 94.15 in the first cycle, and retained an excellent %FAME of 88.87 after five consecutive cycles. PMID:24525218

Witoon, Thongthai; Bumrungsalee, Sittisut; Vathavanichkul, Peerawut; Palitsakun, Supaphorn; Saisriyoot, Maythee; Faungnawakij, Kajornsak

2014-03-01

154

Porosity, surface area, and particle size effects of CaO reacting with SO sub 2 at 1100c  

Microsoft Academic Search

This paper gives results of tests for the reactivity of calcium oxide (CaO) sorbents derived from calcium hydroxide (Ca(OH)â) and calcium carbonate (CaCOâ) to gaseous sulfur dioxide (SOâ) in a nitrogen atmosphere with a nominal 1100 C, entrained flow reactor and a solids residence time of 0.74 s. The research included direct examination of the combined effect of porosity, particle

B. K. Gullett; J. A. Blom; R. T. Cunningham

1988-01-01

155

Measurements of conductivity in liquids. Application to 2CaO Al_{2O3SiO2}  

NASA Astrophysics Data System (ADS)

This paper describes an experimental set-up designed to measure the conductivity of alumino-silicates melts at different temperatures up to 1650 ^{circ C}. This conductivity cell has allowed to study the conductivity versus temperature of the gehlenite (2CaO Al_{2O3SiO2}) during the solidification and fusion processes. It might be useful to improve the knowledge in glass-forming liquids.

Gruener, G.; Dembinski, K.; Bouvier, A.; Loup, J. P.; Odier, P.

1998-10-01

156

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

Microsoft Academic Search

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

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

1992-01-01

157

Electronic conductivities of commercial ZrO 2 + 3 to 4 wt pct CaO electrolytes  

Microsoft Academic Search

Potentiostatic electrochemical experiments with liquid metal electrodes have been analyzed to provide values for the mixed\\u000a electrical conduction parameters (PMion, o?o, Oo , Po,P\\u000a o, and E O,C.) associated with commercial-grade ZrO2 + 3 to 4 wt pct CaO electrolytes. Good agreement between experimental and calculated values for the open-circuit cell voltage,E o. c., for relatively high oxygen concentrations in

Lawrence M. Friedman; Karl E. Oberg; William M. Boorstein; Robert A. Rapp

1973-01-01

158

CaO insulator and Be intermetallic coatings on V-base alloys for liquid-lithium fusion blanket applications  

Microsoft Academic Search

The objective of this study is to develop (a) stable CaO insulator coatings at the liquid-Li\\/structural-material interface, with emphasis on electrically insulating coatings that prevent adverse MHD-generated currents from passing through the V-alloy wall, and (b) stable Be-V intermetallic coatings for first-wall components that face the plasma. Electrically insulating and corrosion-resistant coatings are required at the liquid-Li\\/structural interface in fusion

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

1995-01-01

159

Gas-solid carbonation of Ca(OH)2 and CaO particles under non-isothermal and isothermal conditions by using a thermogravimetric analyzer  

E-print Network

1 Gas-solid carbonation of Ca(OH)2 and CaO particles under non-isothermal and isothermal conditions Gas Control 11, 3 (2012) 172-180" DOI : 10.1016/j.ijggc.2012.08.009 #12;2 Abstract The gas-solid, quantify the gas-solid carbonation extent and the carbonation kinetics of Ca(OH)2 and CaO; and secondly

Boyer, Edmond

160

First-principles simulations of CaO and CaSiO3 liquids: structure, thermodynamics and diffusion  

NASA Astrophysics Data System (ADS)

We have performed first-principles molecular dynamics simulations of CaO and CaSiO3 liquids over broad ranges of pressure (0-150 GPa) and temperature (2,500-8,000 K) within density-functional theory. The simulated liquid structure changes considerably on compression with the mean cation-anion coordination numbers increasing nearly linearly with volume. The Ca-O coordination number increases from 5 (7) near the ambient pressure to 8 (10) at high pressure for CaO (CaSiO3) liquid. The Si-O coordination number increases from 4 to 6 over the same pressure regime. Our results show that both liquids are much more compressible than their solid counterparts implying the possibility of liquid-solid density crossovers at high pressure. The Grüneisen parameter of both the liquids increases with pressure, which is opposite in case of crystalline phases. The calculated self-diffusion coefficients strongly depend on temperature and pressure, thereby requiring non-Arrhenian representation with variable activation volume. The diffusivity differences between the two liquids tend to be large at low-temperature and low-pressure regime. Also, comparisons with MgSiO3 liquid suggest that network modifier cations Ca and Mg behave similarly though Ca is more coordinated and more mobile as compared to Mg.

Bajgain, Suraj K.; Ghosh, Dipta B.; Karki, Bijaya B.

2015-01-01

161

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

SciTech Connect

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.

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

1996-02-01

162

Individuality and Stability in Male Songs of Cao Vit Gibbons (Nomascus nasutus) with Potential to Monitor Population Dynamics  

PubMed Central

Vocal individuality and stability has been used to conduct population surveys, monitor population dynamics, and detect dispersal patterns in avian studies. To our knowledge, it has never been used in these kinds of studies among primates. The cao vit gibbon is a critically endangered species with only one small population living in a karst forest along China-Vietnam border. Due to the difficult karst terrain, an international border, long life history, and similarity in male morphology, detailed monitoring of population dynamics and dispersal patterns are not possible using traditional observation methods. In this paper, we test individuality and stability in male songs of cao vit gibbons. We then discuss the possibility of using vocal individuality for population surveys and monitoring population dynamics and dispersal patterns. Significant individuality of vocalization was detected in all 9 males, and the correct rate of individual identification yielded by discriminant function analysis using a subset of variables was satisfactory (>90%). Vocal stability over 2–6 years was also documented in 4 males. Several characters of cao vit gibbons allowed long-term population monitoring using vocal recordings in both China and Vietnam: 1) regular loud calls, 2) strong individuality and stability in male songs, 3) stable territories, and 4) long male tenure. During the course of this research, we also observed one male replacement (confirmed by vocal analysis). This time- and labor-saving method might be the most effective way to detect dispersal patterns in this transboundary population. PMID:24788306

Ma, Chang-Yong; Fei, Han-Lan; Fan, Peng-Fei

2014-01-01

163

Intermitência alfvênica gerada por caos na atmosfera solar e no vento solar  

NASA Astrophysics Data System (ADS)

Dados medidos no vento solar rápido proveniente dos buracos coronais revelam que os plasmas no meio interplanetário são dominados por flutuações Alfvênicas, caracterizadas por uma alta correlação entre as variações do campo magnético e da velocidade do plasma. As flutuações exibem muitas características esperadas em turbulência magneto-hidrodinâmica totalmente desenvolvida, tais como intermitência e espectros contínuos. Contudo, os mecanismos responsáveis pela evolução de turbulência Alfvênica intermitente não são completamente compreendidos. Neste trabalho a teoria de caos é usada para explicar como sistemas Alfvênicos, modelados pela equação Schrödinger não-linear derivativa e pela equação Kuramoto-Sivashinsky, podem se tornar fortemente caóticos à medida em que parâmetros do plasma são variados. Pequenas perturbações no parâmetro de dissipação podem fazer com que o sistema mude bruscamente de um regime periódico, ou fracamente caótico, para um regime fortemente caótico. As séries temporais das flutuações do campo magnético nos regimes fortemente caóticos exibem comportamento intermitente, em que fases laminares ou fracamente caóticas são interrompidas por fortes estouros caóticos. É mostrado que o regime fortemente caótico é atingido quando as soluções periódicas ou fracamente caóticas globalmente estáveis interagem com soluções do sistema que são fortemente caóticas, mas globalmente instáveis. Estas soluções globalmente instáveis são conjuntos caóticos não-atrativos conhecidos como selas caóticas, e são responsáveis pelos fortes estouros nos regimes intermitentes. Selas caóticas têm sido detectadas experimentalmente em uma grande variedade de sistemas, sendo provável que elas desempenhem um papel importante na turbulência intermitente observada em plasmas espaciais.

Rempel, E. L.; Chian, A. C.-L.; Macau, E. E. N.; Rosa, R. R.

2003-08-01

164

Heavy doping of H - ion in 12CaO·7Al 2O 3  

NASA Astrophysics Data System (ADS)

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

Hayashi, Katsuro

2011-06-01

165

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

PubMed Central

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

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

2013-01-01

166

Pan-African alkali granites and syenites of Kerala as imprints of taphrogenic magmatism in the South Indian shield  

NASA Technical Reports Server (NTRS)

Granite and syenite plutons with alkaline affinities ranging in age from 550 to 750 Ma sporadically puncture the Precambrian granulites of the Kerala region. All the bodies are small (20 to 60 sq km), E-W to NW-SE elongated elliptical intrusives with sharp contacts and lie on or close to major late Proterozoic lineaments. Geochemical plots of A-F-M and An-Ab-Or relations show an apparent alkali enrichment trend on the former, but the plutons define relatively distinct fields on the latter. Most of the plutons are adamellitic to granitic by chemistry. The variations of SiO2 with log sub 10 K2O/MgO (1) brings out the distinct alkaline nature of the plutons. Some of the granites are extremely potassic, like the Peralimala pluton, which shows up to 11.8 percent K2O. On a SiO2-Al2O3-Na2O+K2O (mol percent) plot, the plutons vary from peraluminous to peralkaline, but none are nepheline normative. Low MgO, low to moderate CaO and high Fe2O3/FeO values are other common characteristics. Among trace elements, depletion of Ba, Sr and Rb with high K/Ba and K/Rb values are typical. Overall, the plutons show a trend of decreasing K/Rb ratio with increasing K content. Individual plutons show more clearly defined trends similar to those from granitic masses characterized by plagioclase fractionation.

Santosh, M.; Drury, S. A.; Iyer, S. S.

1988-01-01

167

Overcoming the polarization catastrophe in the rocksalt oxides MgO and CaO  

NASA Astrophysics Data System (ADS)

Interfaces between dissimilar polar materials may provide a pathway to new device functionality, including high carrier mobility layers at the interface. The development of these materials has proven challenging, in part because of the high energy cost of forming polar surfaces. Our density functional theory calculations explore the mechanisms by which a real material satisfies the electrostatic criteria for stability imposed by a polar surface. The consequences of polarity are studied by comparing the formation energies, charge distribution, and electronic structure of a number of low-index surfaces of rocksalt MgO and CaO. These surfaces are explored both in their bare, undecorated form as well as with surface reconstructions and adsorbed foreign species. Our ground-state surface energies are extended to relevant environmental conditions by use of ab initio thermodynamics. We find that the high energy of bare polar surfaces is the result of the significant charge redistribution that arises to compensate the polarity and pushes electronic states into the forbidden band gap. Other mechanisms of polarity compensation (reconstruction or foreign species adsorption) are therefore seen more frequently. We explain the experimental observations of surface roughness during growth in the [111] direction. In typical epitaxial growth conditions, there is preferential formation of an octopolar reconstruction of the {111} surface, which exposes {001}-type nanofacets. The low energy of the {001} surface likely causes these facets to grow, leading to a rough surface morphology. Our results indicate that when water vapor is present during growth, a smooth, polar surface can be stabilized by the formation of a hydroxyl layer.

Gaddy, Benjamin E.; Paisley, Elizabeth A.; Maria, Jon-Paul; Irving, Douglas L.

2014-09-01

168

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

PubMed

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

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

2014-08-01

169

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

PubMed

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:25474971

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

2014-08-01

170

Calibration of a new Model for Estimating the Density, Coefficient of Thermal Expansion, Sound Speed, and Compressibility of Multicomponent Silicate Liquids at Reference Pressure  

NASA Astrophysics Data System (ADS)

Ghiorso (2000, EOS 81[48], F1295) proposed a new equation of state for molten silicate liquids. This equation is designed to facilitate the extrapolation of reference pressure volumetric data to pressures in the Earth corresponding to the base of the mantle transition zone. Extrapolation is performed with a minimal number of adjustable parameters and avoids the singularities and instabilities associated with the Birch-Murnaghan and Vinet equations when these are applied to silicate melts. Here, we calibrate reference pressure (105 Pa) parameters for the proposed silicate liquid equation of state from literature data on measurements of densities and sound speeds of molten liquids and from volumetric measurements on supercooled liquids obtained at their glass transition temperatures. A model for the temperature- and compositionally-dependent, reference-pressure volume (density) in the system K2O-Na2O-CaO-MgO-FeO-NiO-CoO-Fe2O3-Al2O3-TiO2-SiO2 is obtained for liquids with CaO mole fraction < 0.5. Precision of data recovery is 0.55% for Fe-absent liquids and 0.95% for Fe-bearing liquids. Internally consistent expressions for the reference pressure compressibility and its temperature dependence are formulated from a calibration of sound speeds in molten liquids. A model for the temperature- and compositionally-dependent relaxed sound speed in the system K2O-Na2O-CaO-MgO-FeO-Fe2O3-Al2O3-TiO2-SiO2 is obtained. Precision of data recovery is 1.7%. In contrast to previous workers, we find that effect of pressure on the volume of silicate melts (i.e. dV/dP) is more accurately assessed by first calibrating a model equation for the speed of sound and subsequently using this calibration to calculate a value for dV/dP, rather than estimating dV/dP for each experimental datum from the sound speed and modeling the derived quantity directly. Linear mixing relations for model parameters are utilized in calibrations of both the density and the sound speed with the addition of a quadratic composition term in Na2O and SiO2 required to accurately reproduce sound speed measurements. The resulting mixing relations for dV/dP at the reference pressure are weakly non-linear. The mathematical structure of the equation of state renders the volume of mixing a non-linear function of composition at elevated pressure.

Ghiorso, M. S.; Kress, V. C.

2003-12-01

171

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

SciTech Connect

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.

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

2013-08-01

172

Kinetics of wetting for MgO, CaO, and BeO by Pd, Pt, and Rh melts  

NASA Astrophysics Data System (ADS)

The wetting of magnesium, calcium, and beryllium oxides (MgO, CaO, and BeO) is considered, depending on the ratios of the surface tensions of the oxides to the melts at inequality ?sg/?lg < 1 characteristic of metallophobic solid surfaces. It is shown that the changes in the wetting angle with temperature during isothermal exposure are determined by the ratio of the surface tensions of the phases ?MgO/?Me. It is found that the wetting angle moves down or up when the ratios of the surface tensions increase or decrease, respectively, depending on the values of ?sg and ?lg.

Timofeev, A. I.; Chentsov, V. P.

2015-01-01

173

Heterogeneous-nucleation and glass-formation studies of 56Ga2O3-44CaO  

NASA Technical Reports Server (NTRS)

Glass formation and heterogeneous crystallization are described for the reluctant-glass-forming 56Ga2O3-44CaO eutectic composition. The times and temperatures for nucleation at various cooling rates and experimental conditions were measured and empirical continuous-cooling-crystallization boundaries were constructed for various heterogeneous nucleation processes. A definition for an empirical critical cooling rate to form a glass from reluctant borderline glass formers is proposed, i.e., the cooling rate that results in glass formation in 95 percent of the quenching experiments.

Ethridge, Edwin C.; Curreri, Peter A.; Pline, David

1987-01-01

174

Property and metallogenic characteristics of alkali-rich porphyry in western margin of Yangtze Platform  

Microsoft Academic Search

The age of alkali-rich porphyries in the western margin of Yangtze Platform is 30–50 Ma; the minerals mainly are orthoclase,\\u000a quartz, plagioclase; the chemical composition is alkali-rich [(K2O+Na2O)>8%], highpotash[(K2O+Na2O)=5.09%?8.30%]; the content of ?REE is relatively low, LREE is concentrated, without anomaly of europium; the average initial\\u000a ratio of 87Sr\\/86Sr is 0.7073; the value of ?34S similar to that of the

Xiangzhao Hu

1998-01-01

175

Journal of the Korean Physical Society, Vol. 51, July 2007, pp. S32S35 Structure of a Nanocrystalline Phase with Second Harmonic Generation  

E-print Network

formed in TeO2-based glasses is a key factor for fabrication of glass-ceramic with SHG. In this study, we of the 10K2O-4Na2O-14Nb2O5-72TeO2 glass-ceramic with second harmonic generation were studied by using an energy dispersive method in X-ray spectroscopy and XRD. The Bravais lattice of 10K2O-4Na2O-14Nb2O5-72TeO2

Pak, Hyuk Kyu

176

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

NASA Astrophysics Data System (ADS)

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.

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

2010-03-01

177

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

178

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

NASA Astrophysics Data System (ADS)

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 .

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

2009-08-01

179

Acute toxicity of cadmium to fish Labeo rohita and copepod Diaptomus forbesi pre-exposed to CaO and KMnO 4  

Microsoft Academic Search

96-h LC50 values of cadmium (Cd) to fish Labeo rohita and the copepod Diaptomus forbesi, determined by static bioassays, were, respectively, 89.5 and 10.2 mg\\/l. LC50 values increased significantly when fish pre-exposed to 100–350 mg\\/l CaO or 0.5–1.5 mg\\/l KMnO4 for 4 d and the copepod to 20–70 mg\\/l CaO or 0.25–1.0 mg\\/l KMnO4 for same period. The LC50 values

Tapas Kumar Dutta; Anilava Kaviraj

2001-01-01

180

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

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

Cao, Jianming

181

Copyrighted (Textbook) Fei Hu and Xiaojun Cao, Wireless Sensor Networks: Principles and Practice, CRC Press Page 1 Chapter 4: Routing in Wireless Sensor  

E-print Network

Copyrighted (Textbook) Fei Hu and Xiaojun Cao, Wireless Sensor Networks: Principles and Practice, CRC Press Page 1 Chapter 4: Routing in Wireless Sensor Networks 4.1 Introduction to Routing in Wireless Sensor Networks Wireless Sensor Networks (WSNs) is a distributed wireless ad-hoc network

Hu, Fei

182

Use of CaO as an activator for producing a price-competitive non-cement structural binder using ground granulated blast furnace slag  

SciTech Connect

The use of calcium oxide (CaO) demonstrates a superior potential for the activation of ground granulated blast furnace slag (GGBFS), and it produces a higher mechanical strength than calcium hydroxide [Ca(OH){sub 2}]. The mechanical strength differences between CaO- and Ca(OH){sub 2}-activated GGBFS binders are explored using isothermal calorimetry, powder X-ray diffraction, thermogravimetric and differential thermal analysis (TGA and DTA) as well as compressive strength testing. Calcium silicate hydrate (C–S–H), Ca(OH){sub 2} and a hydrotalcite-like phase are found as reaction products in all samples. The TGA and DTA results indicate that the use of CaO produces more C–S–H, although this is not likely to be the primary cause of higher strength development in the CaO-activated GGBFS. Rather, other factors such as porosity may govern the strength at a higher order of magnitude. Significant reduction of Ca(OH){sub 2} occurs only with the use of Ca(OH){sub 2}, followed by the formation of carbonate (CaCO{sub 3}), indicating carbonation. -- Highlights: •CaO showed a better potential for the activation of GGBFS than Ca(OH){sub 2}. •Strength test, XRD, TGA/DTA and isothermal calorimetry are used. •C-S-H, Ca(OH){sub 2}, and a hydrotalcite-like phase are found in all samples. •The use of Ca(OH){sub 2} causes some degree of carbonation.

Kim, Min Sik; Jun, Yubin; Lee, Changha, E-mail: clee@unist.ac.kr; Oh, Jae Eun, E-mail: ohjaeeun@unist.ac.kr

2013-12-15

183

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 ...

184

An automatic method for burn scar mapping using support vector X. CAO{{, J. CHEN*{, B. MATSUSHITA, H. IMURA" and L. WANG{{  

E-print Network

on the ecosystem and the climatic system. We have developed an automatic burn scar mapping method using daily temperature and vegetation water content, respectively, and an automatic region growing method basedAn automatic method for burn scar mapping using support vector machines X. CAO{{, J. CHEN*{, B

Wang, Le

185

Dynamical localization in microdisk W. Fang1, H. Cao1, V. A. Podolskiy2,3, and E. E. Narimanov2  

E-print Network

Dynamical localization in microdisk lasers W. Fang1, H. Cao1, V. A. Podolskiy2,3, and E. E University, Corvallis, OR 97331 w-fang@northwestern.edu; VP:vpodolsk@physics.orst.edu; evgenii, 195304 (2001). 6. J. U. N¨ockel, A. D. Stone, G. Chen, H. Grossman and R. K. Chang, "Directional emission

Cao, Hui

186

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

by the air conditioning units (ACUs) with large scale fans into the plenum thereby pressurizing itNUMERICAL 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

187

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

188

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

NASA Astrophysics Data System (ADS)

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.

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

1992-08-01

189

Hydrogen-rich gas production via CaO sorption-enhanced steam gasification of rice husk: a modelling study.  

PubMed

Gasification is a thermochemical process in which solid or liquid fuels are transformed into synthesis gas through partial oxidation. In this paper, a kinetic model of rice husk gasification has been developed, which is interesting for the applications of the syngas produced. It is a zero-dimensional, steady-state model based on global reaction kinetic, empirical correlation of pyrolysis and is capable of predicting hydrogen yield in the presence of sorbent CaO. The model can also be used as a useful tool to investigate the influence of process parameters including steam/biomass ratio, CaO/fuel ratio (CaO/Fuel), and gasification temperature on hydrogen efficiency, CO2 capture ratio (CCR), and average carbonation conversion (Save). Similar to hydrogen formation, CCR also increases with increasing CaO/Fuel, but an opposite trend is exhibited in Save. Model predictions were compared with available data from the literature, which showed fairly good agreement. PMID:25403373

Beheshti, Sayyed Mohsen; Ghassemi, Hojat; Shahsavan-Markadeh, Rasoul; Fremaux, Sylvain

2015-05-01

190

High electron doping to a wide band gap semiconductor 12CaO•7Al2O3 thin film  

NASA Astrophysics Data System (ADS)

High-density electrons (˜1.9×1021cm-3) were doped into a polycrystalline film of a wide band gap (˜7eV) semiconductor 12CaO•7Al2O3 (C12A7) by an in situ postdeposition reduction treatment using an oxygen-deficient C12A7 overlayer. The resultant film exhibits metallic conduction with a Hall mobility of ˜2.5cm2V-1s-1 and a conductivity of ˜800Scm-1. Optical analyses indicate that most of the doped electrons behave as free carriers with an effective mass of 0.82me and the estimated in-grain mobility is 5.2cm2V-1s-1, which agrees reasonably with the value obtained for high-quality single crystals.

Miyakawa, Masashi; Hirano, Masahiro; Kamiya, Toshio; Hosono, Hideo

2007-04-01

191

Growth of shaped 12CaO×7Al 2O 3 crystals by the micro-pulling down method  

NASA Astrophysics Data System (ADS)

12CaO×7Al 2O 3 (C12A7) single crystals have been successfully grown by the micro-pulling down method for the first time. Single and transparent C12A7 crystal was obtained with radio-frequency heating ?-PD system. Phase stability is discussed as a function of oxygen concentration in the growth atmosphere. A minimum 1.0 Vol% O 2 with nitrogen atmosphere yields C12A7 phase. The distribution of Ca, Al and O elements at cross-section part was investigated by the electron probe microanalysis. The crystal composition deviation could be controlled by reducing O 2 gas concentration to 1.0 Vol%.

Liu, Lijuan; Kagamitani, Yuji; Ehrentraut, Dirk; Yokoyama, Chiaki; Fukuda, Tsuguo

2009-01-01

192

Mechanisms of oxygen ion diffusion in a nanoporous complex oxide 12CaO•7 Al2 O3  

NASA Astrophysics Data System (ADS)

We performed a theoretical analysis of O2- diffusion mechanisms in a nanoporous complex oxide 12CaO•7Al2O3 (C12A7). This material can be viewed as a positively charged framework, arranged in subnanometer sized cages, hosting extra-framework O2- ions occupying one in six cages. Using both classical molecular-dynamics simulations and ab initio calculations we demonstrate that the diffusion of O2- species is dominated by the exchange of framework and extra-framework O2- ions rather than by an interstitial diffusion mechanism. The results allow us to rationalize the origins of the experimentally observed high oxide ion conductivity of C12A7 and the stability of its lattice under positive ion-beam irradiation.

Sushko, Peter V.; Shluger, Alexander L.; Hayashi, Katsuro; Hirano, Masahiro; Hosono, Hideo

2006-01-01

193

Environmental controls on plant chemical traits: Using the CAO-VSWIR to characterize patterns in a mediterranean-type ecosystem  

NASA Astrophysics Data System (ADS)

Here we present results from a new imaging spectrometer, the Carnegie Airborne Observatory's (CAO) Visible-Short Wave Infrared (VSWIR) sensor, and we use these data to map key plant functional traits in a semi-arid ecosystem, Jasper Ridge Biological Preserve (Woodside, CA USA). We considered four fundamental plant traits: leaf nitrogen per mass (Nmass, %), leaf carbon per mass (Cmass, %), leaf water fraction (WL), and canopy water fraction (WC).With these maps we ask the following questions: (1) How do these traits vary with environmental gradients and land use history, independent of species composition? (2) Does information about plant community improve our ability to explain trait patterns? And (3) what does the variation within plant communities tell us about the underlying processes driving or limiting this ecosystem? We show that the new CAO-VSWIR combined with partial least squares regression can effectively map these four plant chemical traits across multiple plant functional types (observed v. predicted R2s ranging from 0.55 for WL to 0.84 for Cmass). To consider how these traits varied with environmental gradients we used simultaneous autoregressive modeling and found, in general, that environment and land-use history together explained about a quarter of the variation in each trait, but that information about plant community boundaries dramatically improved our predictive power. While 29 - 44% of the variation in these four traits remained unexplained, when we considered the trait distributions within each plant community we found that most plant communities were sharply peaked (leptokurtic) or near normal, while a few communities were more evenly distributed (platykurtic) for each trait. These results show that, even though environmental gradients play a small but significant role, most of the plant communities at Jasper Ridge are characterized by a narrow range of trait patterns. For the few communities that are highly divergent, possible causal factors include resource limitation, competition, and/or past disturbances.

Dahlin, K.; Asner, G. P.; Field, C. B.

2012-12-01

194

A Systematic Review of the Mysterious Caterpillar Fungus Ophiocordyceps sinensis in Dong-ChongXiaCao (???? D?ng Chóng Xià C?o) and Related Bioactive Ingredients  

PubMed Central

The caterpillar fungus Ophiocordyceps sinensis (syn.† Cordyceps sinensis), which was originally used in traditional Tibetan and Chinese medicine, is called either “yartsa gunbu” or “DongChongXiaCao (???? D?ng Chóng Xià C?o)” (“winter worm-summer grass”), respectively. The extremely high price of DongChongXiaCao, approximately USD $20,000 to 40,000 per kg, has led to it being regarded as “soft gold” in China. The multi-fungi hypothesis has been proposed for DongChongXiaCao; however, Hirsutella sinensis is the anamorph of O. sinensis. In Chinese, the meaning of “DongChongXiaCao” is different for O. sinensis, Cordyceps spp.,‡ and Cordyceps spƒ. Over 30 bioactivities, such as immunomodulatory, antitumor, anti-inflammatory, and antioxidant activities, have been reported for wild DongChongXiaCao and for the mycelia and culture supernatants of O. sinensis. These bioactivities derive from over 20 bioactive ingredients, mainly extracellular polysaccharides, intracellular polysaccharides, cordycepin, adenosine, mannitol, and sterols. Other bioactive components have been found as well, including two peptides (cordymin and myriocin), melanin, lovastatin, ?-aminobutyric acid, and cordysinins. Recently, the bioactivities of O. sinensis were described, and they include antiarteriosclerosis, antidepression, and antiosteoporosis activities, photoprotection, prevention and treatment of bowel injury, promotion of endurance capacity, and learning-memory improvement. H. sinensis has the ability to accelerate leukocyte recovery, stimulate lymphocyte proliferation, antidiabetes, and improve kidney injury. Starting January 1st, 2013, regulation will dictate that one fungus can only have one name, which will end the system of using separate names for anamorphs. The anamorph name “H. sinensis” has changed by the International Code of Nomenclature for algae, fungi, and plants to O. sinensis. PMID:24716152

Lo, Hui-Chen; Hsieh, Chienyan; Lin, Fang-Yi; Hsu, Tai-Hao

2013-01-01

195

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

NASA Astrophysics Data System (ADS)

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.

Ichikawa, Shintaro; Nakamura, Toshihiro

2014-06-01

196

Evidence from high-Ni olivines for a hybridized peridotite/ pyroxenite source for orogenic andesites from the central  

E-print Network

andesites from the central Mexican Volcanic Belt Susanne M. Straub and Alexandra B. LaGatta Lamont Doherty-alkaline andesite melts that combine the high SiO2, Na2O, and K2O abundances of the differentiated continental crust andesites and andesites of the central Mexican Volcanic Belt suggest that this dichotomy reflects

Langmuir, Charles H.

197

Vanadium chlorite from a sandstone-hosted vanadium-uranium deposit, Henry basin, Utah.  

USGS Publications Warehouse

This ore deposit formed by reduction and precipitation of U and V in the presence of organic matter at the interface between a stagnant brine and overlying circulating meteoric water. Some samples of the vanadium chlorite (heated before analysis) contain = or >10% V2O5; in fresh samples most of the V is in the V3+ state. XRD data suggest that Fe and V are concentrated preferentially in the interlayer hydroxide sheets of the chlorite. A d060 value of 1.52 A indicates that the chlorite probably has a dioctahedral structure distended by the presence of octahedral Fe and V; it is a IIb polytype. The V ore zone is flanked by peripheral zones with perfectly ordered chlorite/smectite containing much less V than the pure chlorite. Chemical analysis of a sample heated to 900oC before analysis gave SiO2 44.89, Al2O3 25.14, TiO2 0.35, Fe2O3 8.29, MgO 8.47, CaO 0.84, Na2O 0.27, K2O 2.18, Li2O 0.16, UO3 0.92, V2O5 9.14, = 100.65, together with Cr 10, Mn 200, Co 150, Ni 5.8, Cu 10, Zn 140 ppm; XRD, DTG, TG and IR curves are presented. -R.A.H.

Whitney, G.; Northrop, H.R.

1986-01-01

198

Mineralogical and chemical compositions of the paleosols of different ages buried under kurgans in the southern Ergeni region and their paleoclimatic interpretation  

NASA Astrophysics Data System (ADS)

The chemical and mineralogical compositions and the contents and properties of the organic matter were studied in the paleosols of different ages buried under the kurgan group "Kalmykia" in the southern part of the Ergeni Upland. The investigated sequence of soils included profiles developed on the given territory about 5100, 4410, 4260, 4120, 3960, and 600 yrs ago. The background light chestnut soil was also examined. The results of our study showed that the earlier established climate changes in this area during the second half of the Holocene are reflected in the chemical and mineralogical compositions of the soils. These characteristics can be used as indicators of the paleoclimatic conditions together with some petrophysical characteristics, such as the magnetic susceptibility of the soil samples. The study of the mineralogical composition of the clay fraction of the paleosols attests to the transformation of the smectitic phase, accumulation of illites, and destruction of chlorites manifested at different degrees. It is argued that the geochemical indices—CIA, Al2O3/(CaO + MgO + K2O + Na2O), Rb/Sr, and Ba/Sr—are sensitive to climate changes and reflect the transformation of the mineral soil mass and the soil genesis.

Tatyanchenko, T. V.; Alekseeva, T. V.; Kalinin, P. I.

2013-04-01

199

Beach sands from Baja California Peninsula, Mexico  

NASA Astrophysics Data System (ADS)

Fifty beach locations were sampled in Baja California Peninsula, México, in order to characterize textural and compositional parameters. The western beach sands are mainly associated with a lower relief coastal plain and high energy of waves and currents with the beach sands of the eastern littoral zone. Finer, better sorted and low carbonate and rich quartz and feldspar contents are observed for the western beach sands when compared to the eastern beach sands. The mineralogical maturity and provenance index are greater for the western beach sands than for the eastern beach sands. These contrasts may be explained by differences on coastal plain relief and differences on hydrodynamic energy of waves and currents that are responsible for the rock fragment dilution by enrichment of more stable quartz debris. Finally, some distinctions were found for Na 2O-K 2O-CaO values. This is thought to be a result of the presence of some samples from the eastern coastline with higher values in CaO content, probably due to the presence of basaltic rocks.

Carranza-Edwards, Arturo; Bocanegra-García, Gerardo; Rosales-Hoz, Leticia; de Pablo Galán, Liberto

1998-08-01

200

High-Temperature Viscosity of Commercial Glasses  

SciTech Connect

Arrhenius models were developed for glass viscosity within the processing temperature of six types of commercial glasses: low-expansion-borosilicate glasses, E glasses, fiberglass wool glasses, TV panel glasses, container glasses, and float glasses. Both local models (for each of the six glass types) and a global model (for the composition region of commercial glasses, i.e., the six glass types taken together) are presented. The models are based on viscosity data previously 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. First-order models were applied to relate Arrhenius coefficients to the mass fractions of 15 components: SiO2, TiO2, ZrO2, Al2O3, Fe2O3, B2O3, MgO, CaO, SrO, BaO, PbO, ZnO, Li2O, Na2O, K2O. The R2 is 0.98 for the global model and ranges from .097 to 0.99 for the six local models. 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 5 to 400 Pa?s.

Hrma, Pavel R.

2006-08-31

201

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

NASA Technical Reports Server (NTRS)

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).

Zaplatynsky, I.

1978-01-01

202

High-Temperature Viscosity Of Commercial Glasses  

SciTech Connect

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.

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

2005-01-01

203

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

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.

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

1982-01-01

204

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

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

205

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

NASA Technical Reports Server (NTRS)

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).

Righter, K.; Ghiorso, M.

2009-01-01

206

A Structurally Based Viscosity Model for Oxide Melts  

NASA Astrophysics Data System (ADS)

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).

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

2014-04-01

207

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

USGS Publications Warehouse

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.

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

1984-01-01

208

Vegetable ash as raw material in the production of glasses and enamels, for example the contemporary vegetable ashes from Burgundy, France  

E-print Network

The powdery nature and high alkali content of vegetable ashes make them ideal raw materials to be used as modifiers of silicate compositions (glasses, enamels and ceramics). Their utilisation since ancient times is described in the literature of the history of glasses, but studies on the analyses of their composition are still limited. We discuss here the compositions of tree and shrub ashes (wattle, hawthorn, oak, green oak, olive wood, elm, poplar, apple tree, vine shoot), of plants (carex, fern, dogwood), of cereals (wheat, maize, rice), threshing waste and hay, mainly harvested in Maconnais, near Taiz\\'e (Sa\\^one-et-Loire, France), by the potter Brother D. de Montmolin. The contributions in alkali modifiers (Na2O, K2O), alkaline-earth (CaO, MgO) and in silica are discussed in view of the data gathered from the literature of the history of techniques used in the production of ceramics, enamels and glasses. The huge variation in composition is usually attributed to recycling and is questioned by the very br...

Colomban, Philippe; De Montmollin, Frère Daniel; Krainhoefner, Frère Luc

2010-01-01

209

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

PubMed

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

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

2014-03-01

210

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

Microsoft Academic Search

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

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

2007-01-01

211

Preparation of CaO as OLED getter material through control of crystal growth of CaCO{sub 3} by block copolymers in aqueous solution  

SciTech Connect

As the starting materials of organic light-emitting diode (OLED) getter, calcium carbonate (CaCO{sub 3}) particles with various shapes and crystal structures have been successfully prepared with additives (L64 or PEGPG), which contain blocks of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO). These CaCO{sub 3} particles were calcinated into highly crystalline calcium oxide (CaO) nanoparticles with high capacity of water adsorption up to 14.23 wt.%. The CaCO{sub 3} and CaO particles prepared at various conditions were characterized using the field emission scanning electron microscopy (FE-SEM), Fourier transform infrared microscopy (FT-IR), X-ray powder diffraction (XRD), and dynamic vapor sorption (DVS) method.

Park, Jae-Hyung [Department of Chemical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Oh, Seong-Geun [Department of Chemical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)], E-mail: seongoh@hanyang.ac.kr

2009-01-08

212

The Vibrational Frequencies of CaO2, ScO2, and TiO2: A Comparison of Theoretical Methods  

NASA Technical Reports Server (NTRS)

The vibrational frequencies of several states of CaO2, ScO2, and TiO2 are computed at using density functional theory (DFT), the Hatree-Fock approach, second order Moller-Plesset perturbation theory (MP2), and the complete-active-space self-consistent-field theory. Three different functionals are used in the DFT calculations, including two hybrid functionals. The coupled cluster singles and doubles approach including the effect of unlinked triples, determined using perturbation theory, is applied to selected states. The Becke-Perdew 86 functional appears to be the cost effective method of choice, although even this functional does not perform well for one state of CaO2. The MP2 approach is significantly inferior to the DFT approaches.

Rosi, Marzio; Bauschlicher, Charles W., Jr.; Chertihin, George V.; Andrews, Lester; Arnold, James O. (Technical Monitor)

1997-01-01

213

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

NASA Technical Reports Server (NTRS)

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.

Zaplatynsky, Isidor

1988-01-01

214

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

SciTech Connect

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.

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

215

An Electro-Deposited IrOx Thin Film pH Sensor C. M. Nguyen, H. Cao, W. D. Huang, and J.-C. Chiao  

E-print Network

pH levels with indicators such as neutral red or umbelliferone are limited for in-situ experiments solutions with different pH levels of 2, 4, 7, 10 were used to test the performance. A unit-gain bufferAn Electro-Deposited IrOx Thin Film pH Sensor C. M. Nguyen, H. Cao, W. D. Huang, and J.-C. Chiao

Chiao, Jung-Chih

216

A chromodomain protein encoded by the arabidopsis CAO gene is a plant-specific component of the chloroplast signal recognition particle pathway that is involved in LHCP targeting.  

PubMed Central

A recessive mutation in Arabidopsis, named chaos (for chlorophyll a/b binding protein harvesting-organelle specific; designated gene symbol CAO), was isolated by using transposon tagging. Characterization of the phenotype of the chaos mutant revealed a specific reduction of pigment binding antenna proteins in the thylakoid membrane. These nuclear-encoded proteins utilize a chloroplast signal recognition particle (cpSRP) system to reach the thylakoid membrane. Both prokaryotes and eukaryotes possess a cytoplasmic SRP containing a 54-kD protein (SRP54) and an RNA. In chloroplasts, the homolog of SRP54 was found to bind a 43-kD protein (cpSRP43) rather than to an RNA. We cloned the CAO gene, which encodes a protein identified as Arabidopsis cpSRP43. The product of the CAO gene does not resemble any protein in the databases, although it contains motifs that are known to mediate protein-protein interactions. These motifs include ankyrin repeats and chromodomains. Therefore, CAO encodes an SRP component that is unique to plants. Surprisingly, the phenotype of the cpSRP43 mutant (i.e., chaos) differs from that of the Arabidopsis cpSRP54 mutant, suggesting that the functions of the two proteins do not strictly overlap. This difference also suggests that the function of cpSRP43 is most likely restricted to protein targeting into the thylakoid membrane, whereas cpSRP54 may be involved in an additional process(es), such as chloroplast biogenesis, perhaps through chloroplast-ribosomal association with chloroplast ribosomes. PMID:9878634

Klimyuk, V I; Persello-Cartieaux, F; Havaux, M; Contard-David, P; Schuenemann, D; Meiherhoff, K; Gouet, P; Jones, J D; Hoffman, N E; Nussaume, L

1999-01-01

217

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

Microsoft Academic Search

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

Jesús Delgado; María P. Aznar; José Corella

1997-01-01

218

Comparative SO sub 2 reactivity of CaO derived from CaCO sub 3 and Ca(OH) sub 2  

Microsoft Academic Search

In an effort to develop a low-cost retrofit technology for control of sulfur dioxide (SOâ) emissions from coal-fired utility plants, boiler injection of dry calcium-based sorbents to form calcium sulfate (CaSOâ) has been widely studied. The effects of such parameters as injection temperature, sorbent surface area, and SOâ concentration on the reaction between the active species, calcium oxide (CaO), and

B. K. Gullett; K. R. Bruce; L. O. Beach

1989-01-01

219

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

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

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

2002-01-01

220

Oxidation Studies of SiAlON/MgAlON Ceramics with Fe2O3 and CaO Impurities, Part I: Kinetics  

NASA Astrophysics Data System (ADS)

T he oxidation behaviors of composites SiAlON/MgAlON phases (?-SiAlON, 15R-SiAlON and MgAlON) synthesized from the residue during the leaching treatment of salt cake and corresponding synthetic samples were investigated in air by thermogravimetric measurements. Combined kinetics, viz. linear law + arctan law + parabolic law, are used to describe the kinetics of oxidation in isothermal mode. The oxidation studies reveal the effects of impurities, namely, Fe2O3 and CaO, present in the salt cake residue. The addition of Fe2O3 results in a lower activation energy and more aggressive oxidation. The addition of CaO caused the shrinkage during the synthesis and liquid formation during the oxidation above 1673 K (1400 °C). The impurities of CaO and Fe2O3 in the leaching residue can result in an aggressive oxidation at low temperature and a protective oxidation at temperatures above the eutectic point.

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

2013-02-01

221

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

SciTech Connect

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.

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

1995-09-01

222

Acute toxicity of cadmium to fish Labeo rohita and copepod Diaptomus forbesi pre-exposed to CaO and KMnO4.  

PubMed

96-h LC50 values of cadmium (Cd) to fish Labeo rohita and the copepod Diaptomus forbesi, determined by static bioassays, were, respectively, 89.5 and 10.2 mg/l. LC50 values increased significantly when fish pre-exposed to 100-350 mg/l CaO or 0.5-1.5 mg/l KMnO4 for 4 d and the copepod to 20-70 mg/l CaO or 0.25-1.0 mg/l KMnO4 for same period. The LC50 values also increased when the pre-exposure period of CaO was increased to 12 d at concentration 100 mg/l for fish and 20 mg/l for copepod. All fish died when pre-exposed to 1.5 mg/l KMnO4 for 8 d. But LC50 values of Cd to copepod increased when pre-exposure period of 0.5 mg/l KMnO4 was increased from 4 to 8 d. PMID:11272918

Dutta, T K; Kaviraj, A

2001-03-01

223

Dielectric properties of (CuO, CaO2, and BaO)y/CuTl-1223 composites  

NASA Astrophysics Data System (ADS)

We synthesized (CuO, CaO2, and BaO)y/Cu0.5Tl0.5Ba2Ca2Cu3O10-? (y = 0, 5%, 10%, 15%) composites by solid-state reaction and characterized them by x-ray diffraction, scanning electron microscopy, dc-resistivity, and Fourier transform infrared spectroscopy. Frequency and temperature dependent dielectric properties, such as real and imaginary parts of the dielectric constant, dielectric loss, and ac-conductivity of these composites were studied by capacitance and conductance measurements as a function of frequency (10 kHz to 10 MHz) and temperature (78 to 300 K). X-ray diffraction analysis reveals that the characteristic behavior of the superconductor phase and the structure of Cu0.5Tl0.5Ba2Ca2Cu3O10-? are nearly undisturbed by doping with nanoparticles. Scanning electron microscopy images show the improvement in the intergranular linking between the superconducting grains occurring with increasing nanoparticle concentration. Microcracks are healed up with these nanoparticles, and superconducting volume fraction is also increased. Dielectric properties of these composites strongly depend on the frequency and temperature. Zero resistivity critical temperature and dielectric properties show opposite trends with the addition of nanoparticles to the Cu0.5Tl0.5Ba2Ca2Cu3O10-? superconductor matrix.

Mumtaz, M.; Kamran, M.; Nadeem, K.; Jabbar, Abdul; Khan, Nawazish A.; Saleem, Abida; Tajammul Hussain, S.; Kamran, M.

2013-07-01

224

From insulator to electride: a theoretical model of nanoporous oxide 12CaO.7Al2O3.  

PubMed

Recently, a novel inorganic electride stable at room temperatures has been obtained by reducing a complex nanoporous oxide 12CaO.7Al2O3 (C12A7) in a Ca atmosphere (Matsuishi, S.; Toda, Y.; Miyakawa, M.; Hayashi, K.; Kamiya, T.; Hirano, M.; Tanaka, I.; Hosono, H. Science 2003, 301, 626). In this system, up to 2.3 x 1021/cm3 electrons can be accommodated in a three-dimensional network of cages formed by a positively charged oxide framework. We demonstrate theoretically that at all concentrations, ne, the electrons are neither associated with specific atoms nor fully delocalized. At low ne, the electrons are isolated from each other and resemble the color centers in insulating materials. They are well localized in some of the lattice cages and yield strong inhomogeneous lattice distortions that provide polaron-type cage-to-cage electron hopping. As ne increases, the electrons form a denser electron gas and become more evenly spread over all available lattice cages. At sufficiently high ne, the system becomes metallic but still retains partially localized character of the conducting electrons. We describe the nature of the electronic states at the Fermi level and predict the changes in the optical and magnetic properties of this system as a function of ne. PMID:17243831

Sushko, Peter V; Shluger, Alexander L; Hirano, Masahiro; Hosono, Hideo

2007-01-31

225

Preparation and visible emission of Er-doped 12CaO x 7Al2O3 powder.  

PubMed

Er(3+)-doped 12CaO x 7Al2O3 (C12A7:Er3+) powders were prepared using the sol-gel method. X-ray diffraction, micro-Raman spectra and absorption spectra showed that C12A7:Er3+ powder had been obtained. Sharp and intense Er(3+)-related emission from C12A7:Er3+ powder with different Er3+ concentrations in the visible region at room temperature was investigated by analyzing the local structure of Ca atoms in C12A7, and it revealed that cation sites with low symmetry of the host were beneficial to the photoluminescence of Er3+ ions. The emission lines were attributed to two types of Er3+ centers, isolated Er3+ ions and complex centers formed by aggregation of Er3+ ions. The PL intensity might be affected by free oxygen species relative to Er3+ ions formed by charge compensation. The inverse temperature dependent luminescence from the upper level of 2H11/2 state and that from the lower level of 4S3/2 state implied that the thermalization or thermal equilibrium of electrons between the two closely emission states occurred. PMID:18468174

Wang, D; Liu, Y X; Liu, Y C; Xu, C S; Shao, C L; Li, X H

2008-03-01

226

Strong enhancement of superconductivity in inorganic electride 12CaO·7Al2O3:e- under high pressure  

NASA Astrophysics Data System (ADS)

We present the results of the pressure dependence of the superconductivity of the inorganic electride 12CaO·7Al2O3:e- (C12A7:e-) single crystal through the ac-susceptibility measurement under high pressure. C12A7:e- has the cage structure and the density of states derived from the cages may play an important role in the superconductivity. The superconducting transition temperature ( T c) is ˜ 0.2 K at ambient pressure and monotonically increases up to 1.79 K at 4.7 GPa. The upper critical field H c2 and - dH c2/ dT at T c, in proportion to the density of states (DOS) at Fermi energy becomes larger under high pressure. The superconductivity in C12A7:e- is mediated by the electron-phonon interaction, and the increase of Tc with pressure may arise from a peak structure of the DOS of cage conduction band.

Tanaka, Shigeki; Kato, Tomoki; Miyake, Atsushi; Kagayama, Tomoko; Shimizu, Katsuya; Kim, Sung Wng; Matsuishi, Satoru; Hosono, Hideo

2013-08-01

227

Photoluminescence of Au - formed in 12CaO · 7Al 2O 3 single crystal by Au +-implantation  

NASA Astrophysics Data System (ADS)

Au + ion implantation with fluences from 1 × 10 14 to 3 × 10 16 cm -2 into 12CaO · 7Al 2O 3 (C12A7) single crystals was carried out at a sample temperature of 600 °C. The implanted sample with the fluence of 1 × 10 15 cm -2 exhibited photoluminescence (PL) bands peaking at ˜3.1 and ˜2.3 eV at ?150 K when excited by He-Cd laser (325 nm). This was the first observation of PL from C12A7. These two PL bands are possibly due to intra-ionic transitions of an Au - ion having the electronic configuration of 6 s2, judged from their similarities to those reported on Au - ions in alkali halides. However, when the concentration of the implanted Au ions exceeded the theoretical maximum value of anions encaged in C12A7 (˜2.3 × 10 21 cm -3), surface plasmon absorption appeared in the optical absorption spectrum, suggesting Au colloids were formed at such high fluences. These observations indicate that negative gold ions are formed in the cages of C12A7 by the Au + implantation if an appropriate fluence is chosen.

Miyakawa, M.; Kamioka, H.; Hirano, M.; Kamiya, T.; Hosono, H.

2006-09-01

228

Characterization and optical transition in tb-doped 12CaO x 7Al2O3 powders.  

PubMed

Tb-doped 12CaO x 7Al2O3 (C12A7:Tb3+) powders with strong green emission were prepared using the sol-gel method. X-ray diffraction, micro-Raman spectra, scanning electron microscopy and absorption spectra showed that C12A7:Tb3+ powders with grain size of 200-300 nm were synthesized. Porous powders could be formed as the concentration of Tb3+ was 5 at%. The absorption band around 209 nm was attributed to the host lattice absorption, and the bands around 255 nm and 274 nm were related to the 4f-5d transitions of Tb3+. The absorption intensity of the visible region was enhanced due to the presence of one 100 nm-diameter hole in every grain of C12A7:Tb3+ powders. The emission spectra showed noticeable influence of Tb-Tb cross relaxation, which favored the green photoluminescence (PL) over the blue PL. The study on the concentration quenching indicated that the energy transfers depopulating the 5D3 and 5D4 levels were assigned to the mechanisms of electric dipole-dipole and exchange interaction, respectively. PMID:20355639

Xue, L L; Liu, Y X; Xu, C S; Liu, Y C; Zhao, C J; Zhang, X T

2010-03-01

229

Thermodynamics and kinetics of hydroxide ion formation in 12 CaO x 7 Al2O3.  

PubMed

We have examined the thermodynamics and kinetics of hydroxide (OH-) ions that formed in cages of 12 CaO x 7 Al2O3 (C12A7) with nanoporous structures. It is confirmed using thermogravimetric-evolved gas analyses (TG-EGA) that hydration in C12A7 is mediated by a reaction between an oxide (O2-) ion in the cage and an H2O molecule in the atmosphere to form two OH- ions in the cages. To simply and exactly quantify the OH- content from infrared absorption measurements of OH-stretching band, we propose a method combined with a thermodynamic analysis, allowing the simultaneous determination of the molar extinction coefficient of the OH-band, enthalpy, and entropy for the hydration. Hydration enthalpy in C12A7 is extremely high compared with other oxides and was enhanced by the marked instability of O2- ion in the cage. Consequently, high solubility of OH- ion is retained up to unusually high temperatures. Furthermore, we determined diffusion coefficients of species relevant to the hydration process and demonstrated that inward diffusion of OH- ions is the rate-determining process. PMID:16852465

Hayashi, Katsuro; Hirano, Masahiro; Hosono, Hideo

2005-06-23

230

Insulator -- polaron conductor -- metal transitions in a complex oxide 12CaO.7Al2O3.  

NASA Astrophysics Data System (ADS)

Recent experiments have demonstrated that a complex nano-porous oxide 12CaO.7Al2O3 (C12A7) built of positively charged sub-nanometer cages can be converted from a transparent insulator to a transparent conductor by H2 doping followed by UV-light irradiation with 4--4.5 eV photons [1]. This irradiation induces optical absorption bands with maxima at 0.4 eV and 2.8 eV and high concentrations of unpaired electrons. We use ab initio calculations to reveal the mechanism of photo-induced insulator--conductor transition and the role of H atoms in this process and to elucidate the transport properties of the electrons in this system as a function of electron concentration. Our theoretical modeling suggests that at concentration below 10^20 cm-3 electrons are responsible for the polaron type electrical conductivity with the activation energy close to 0.1 eV as well as for the optical absorption at 0.4 eV and 2.8 eV [2]. We demonstrate that, as the electron concentration exceeds 10^20 cm-3, the character of electronic conductivity changes from polaron type to metallic. [1] K. Hayashi et al., Nature 419, 462 (2002). [2] P.V. Sushko, et al., Phys. Rev. Lett. 91, 126401 (2003); P.V. Sushko et al., Appl. Phys. Lett. 86, 092101 (2005).

Sushko, P.; Shluger, A.; Stoneham, A.; Hayashi, K.; Matsuishi, S.; Hirano, M.; Hosono, H.

2006-03-01

231

Photoluminescence from Au ion-implanted nanoporous single-crystal 12CaO•7Al2O3  

NASA Astrophysics Data System (ADS)

Implantation of Au+ ions into a single crystalline 12CaO•7Al2O3 (C12A7) was performed at high temperatures with fluences from 1×1014 to 3×1016cm-2 . This material is composed of positively charged sub-nanometer-sized cages compensated by extra-framework negatively charged species. The depth profile of concentrations of Au species was analyzed using Rutherford backscattering spectrometry. The measured optical spectra and ab initio embedded cluster calculations show that the implanted Au species are stabilized in the form of negative Au- ions below the fluences of ˜1×1016cm-2 (Au volume concentration of ˜2×1021cm-3 ). These ions are trapped in the cages and exhibit photoluminescence (PL) bands peaking at 3.05 and 2.34eV at temperatures below 150K . At fluences exceeding ˜3×1016cm-2 , the implanted Au atoms form nano-sized clusters. This is manifested in quenching of the PL bands and creation of an optical absorption band at 2.43eV due to the surface plasmon of free carriers in the cluster. The PL bands are attributed to the charge transfer transitions (Au0+e-?Au-) due to recombination of photo-excited electrons (e-) , transiently transferred by ultraviolet excitation into a nearby cages, with Au0 atoms.

Miyakawa, Masashi; Kamioka, Hayato; Hirano, Masahiro; Kamiya, Toshio; Sushko, Peter V.; Shluger, Alexander L.; Matsunami, Noriaki; Hosono, Hideo

2006-05-01

232

Spectroscopic characterization of a multiband complex oxide: Insulating and conducting cement 12CaO·7Al2O3  

NASA Astrophysics Data System (ADS)

Natural 12CaO·7Al2O3 (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. These measurements suggest the existence of a narrow conduction band between the main 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.

McLeod, J. A.; Buling, A.; Kurmaev, E. Z.; Sushko, P. V.; Neumann, M.; Finkelstein, L. D.; Kim, S.-W.; Hosono, H.; Moewes, A.

2012-01-01

233

Characterization and luminescence of Eu3+ ions doped 12CaO 7Al2O3 nanopowders.  

PubMed

Eu3+ ions doped 12CaO 7Al2O3 (C12A7) powders with different Eu3+ concentrations were prepared by sol-gel combined with solid state reaction method. The results of XRD and Raman spectra showed that single cubic phase polycrystalline C12A7:Eu3+ powders were prepared. The absorption peaks attributed to f-f transition of Eu3+ ion can be observed, indicating that Eu3+ had been incorporated into C12A7 lattice site. Visible PL peaks around 578, 588, 614 nm were ascribed to 5D0 --> 7FJ (J = 0, 1, 2) transitions of Eu3+ under the excitation of 488 nm line. The PL of C12A7:Eu3+ showed the strongest emission intensity at Eu3+ concentration of 0.5 at%. Two different types of Eu3+ centers were identified by the two lines from 5D0 --> 7F0 transition emission. The doping mechanism of C12A7:Eu3+ might be attributed to Eu3+ ions substitution for two types of Ca2+ lattice sites in C12A7. The temperature dependent PL spectra of Eu-doped C12A7 were measured in the range from 100 to 300 K under the excitation of 488 nm laser line. The PL intensities as a function of temperature were well fitted by using a unified theoretical model, considering thermal activation and nonradiative energy transfer processes. PMID:22413328

Liu, C G; Liu, Y X; Wang, D; Yan, D T; Xu, C S

2011-11-01

234

Features and mechanism of H- anion emission from 12 CaO x 7 Al2O3 surface.  

PubMed

The hydrogen anion (H-) and other anionic species (O-, OH-, e-) in the gas phase, emitted from the synthesized crystal surface of 12 CaO x 7 Al2O3-H- (C12A7-H-), have been observed. The emission intensity of all the anionic species strongly depends on the sample surface temperature and the extraction field. H- has the highest emission branch ratio, and the extraction field can reduce its apparent activation energy. H- emission current at a microA/cm2-level has been achieved, which is about 4 orders of magnitude higher than that obtained from the thermal desorption process of CaH2. The observed anions of H- and OH- are attributed to their migration from the C12A7-H- cages onto the surface [i.e., Y-(cages) --> Y-(surface) --> Y-(gas phase) (Y = H, OH)]. The weak O- and electron emission would both arise from the dissociation of O2-: O2-(surface) --> O-(surface) + e-(surface) --> O-(gas phase) + e-(space). PMID:16852484

Huang, Fan; Li, Jiang; Wang, Lian; Dong, Ting; Tu, Jing; Torimoto, Yoshifumi; Sadakata, Masayoshi; Li, Quanxin

2005-06-23

235

Geochemical constraints on the petrogenesis of the Paleozoic granitoids of the Sierra de San Luis, Sierras Pampeanas, Argentina  

NASA Astrophysics Data System (ADS)

The Paleozoic granitoids of the Sierra de San Luis comprise the Ordovician tonalite suite (OTS; metaluminous to mildly peraluminous calcic tonalite-granodiorites) and granodiorite-granite suite (OGGS; peraluminous calcic to calc-alkaline granodiorite-monzogranites), as well as the Devonian granite suite (DGS; peraluminous alkali-calcic monzogranites) and monzonite-granite suite (DMGS; metaluminous alkali-calcic quartz monzonite-monzogranite ± granodiorite, mildly peraluminous alkalicalcic monzogranites). The OTS has relatively high K 2O, CaO, and Yb N and low Cr, Ni, Ba, Sr, Rb/Sr, Sr/Y, and (La/Yb) N, as well as negative Eu/Eu ?, high 87Sr/ 86Sr (0.70850-0.71114), and unradiogenic ?Nd(470Ma) (-5.3 to -6.0), which preclude an origin of variably fractionated mantle melts and favour a mafic lower crustal source. The OGGS consists of two granitoids: (1) high-temperature characterized by low Al 2O 3/TiO 2, Rb/Sr, and (La/Yb) N, a smooth negative Eu/Eu ?, and relatively high CaO and (2) low-temperature with high Al 2O 3/TiO 2 and Rb/Sr, low CaO, (La/Yb) N, and Sr/Y, and negative Eu/Eu ?. Melting of metagreywackes at pressures below 10 kbar with a variable supply of water could account for the chemistry of the high-T OGGS, whereas dehydration melting of biotite-bearing metasedimentary sources at low pressures is proposed for the low temperature OGGS. Melting of crustal sources relates to a contemporaneous mafic magmatism. Devonian magmatism is characterized by high Ba, Sr, K 2O, Na 2O, Sr/Y, and (La/Yb) N. Sources for the DGS include metasedimentary or metatonalitic protoliths. Biotite dehydration melting triggered by the addition of heat, supplied by mantle-derived magmas, is proposed. High Ba, Sr, LREE, MgO, Cr, Ni, Zr, and V of the monzonites suggest an enriched lithospheric mantle source. Low Yb and Y and high Sr and (La/Yb) N indicate a garnet-rich residual assemblage ( P ? 10 kbar). Melts for the peraluminous rocks may have derived from a metasedimentary or metaigneous source at lower pressures in a process dominated by biotite consumption and plagioclase in the residue. The Ordovician granitoids are synkinematic with compressive deformation related to the early stages of Famatinian convergence. The Devonian magmatism is synkinematic with a system of shear zones that were active during the Achalian cycle.

de Luchi, M. G. López; Siegesmund, Siegfried; Wemmer, Klaus; Steenken, Andre; Naumann, Rudolf

2007-09-01

236

New data on selected Ivory Coast tektites  

USGS Publications Warehouse

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.

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

1972-01-01

237

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

NASA Astrophysics Data System (ADS)

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.

Feret, J.; Asner, G. P.

2013-12-01

238

Cuprian fraipontite and sauconite from the Defiance-Silver Bill mines, Gleeson, Arizona.  

USGS Publications Warehouse

XRD studies have shown the fine-grained, light blue-green mineral previously identified as turquoise or chrysocolla to be the rare species fraipontite + or - admixed sauconite. Composite microprobe and XRF analyses gave SiO2 24.8, Al2O3 17.3, CaO 0.34, CuO 5.2, ZnO 40.95, H2O (ign. loss, 900oC) 12.8, = 101.39, yielding the formula (Zn1.84Al0.77Cu0.24box 0.13- Ca0.02)3.00(Si1.51Al0.49)2.00O5(OH)4. Semiquantitative emission spectrographic analysis showed Fe 0.007, Mg 0.01, Ca 0.07, Si 10, Al major, Na 0.015, Zn major, Cu 5%; Mn 15, B 150, Be 7, Ni 50, Pb 15, Sc 15, Ga 70 and Ag 1 ppm. It has a 5.331(8), b 9.23(1), c 7.275(6) A, beta 104.15o; H. 3.5-4; Dcalc 3.44, Dobs. 3.08- 3.10; mean refr. ind. approx 1.61. Much of the fraipontite is admixed with sauconite, which may be forming from the fraipontite. XRF analysis of this material gave SiO2 32.8, Al2O3 10.9, MgO < 0.1, CaO 1.51, Na2O < 0.2, K2O < 0.02, TiO2 < 0.02, P2O5 < 0.02, MnO < 0.02, CuO 4.65, ZnO 39.9, ign. loss 13.9, = 103.7.-G.W.R.

Foord, E.E.; Taggart, J.E.; Conklin, N.M.

1983-01-01

239

The dissolution of natural and artificial dusts in glutamic acid  

NASA Astrophysics Data System (ADS)

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.

Ling, Zhang; Faqin, Dong; Xiaochun, He

2014-08-01

240

High-intensity atomic oxygen radical anion emission mechanism from 12CaO·7Al 2O 3 crystal surface  

NASA Astrophysics Data System (ADS)

12CaO · 7Al 2O 3 (C12A7) crystal is an interesting material where a large amount of O -(c) and O 2-(c) can be formed and trapped in the cages when it is sintered in dry oxygen. The emissive features of this material including the emission species, temperature dependence, field dependence, emission branch ratio, emission stability, the effects of water on the emission intensity, have been investigated. The temperature and oxygen pressure dependences of the electrical conductivity have also been measured. The mechanisms of the O - emission have been discussed based on the investigations of the emission and electrical conductivity features.

Li, Quanxin; Hosono, Hideo; Hirano, Masahiro; Hayashi, Katsuro; Nishioka, Masateru; Kashiwagi, Hideo; Torimoto, Yoshifumi; Sadakata, Masayoshi

2003-03-01

241

Abundances and distribution of minerals and elements in high-alumina coal fly ash from the Jungar Power Plant, Inner Mongolia, China  

USGS Publications Warehouse

The fly ash from the Jungar Power Plant, Inner Mongolia, China, is unique because it is highly enriched in alumina (Al2O3>50%). The fly ash mainly consists of amorphous glass and mullite and trace amounts of corundum, quartz, char, calcite, K-feldspar, clay minerals, and Fe-bearing minerals. The mullite content in fly ash is as high as 37.4% because of high boehmite and kaolinite contents in feed coal. Corundum is a characteristic mineral formed during the combustion of boehmite-rich coal.Samples from the economizer were sieved into six size fractions (<120, 120-160, 160-300, 300-360, 360-500, and >500 mesh) and separated into magnetic, mullite+corundum+quartz (MCQ) and glass phases for mineralogical and chemical analysis. The corundum content increases but amorphous glass decreases with decreasing particle size. Fractions of small particle sizes are relatively high in mullite, probably because mullite was formed from fine clay mineral particles under high-temperature combustion condition. Similarly, fine corundum crystals formed in the boiler from boehmite in feed coal. The magnetic phase consists of hematite, magnetite, magnesioferrite, and MgFeAlO4 crystals. The MCQ phase is composed of 89% mullite, 6.1% corundum, 4.5% quartz, and 0.5% K-feldspar.Overall, the fly ash from the power plant is significantly enriched in Al2O3 with an average of 51.9%, but poor in SiO2, Fe2O3, CaO, MgO, Na2O, P2O5, and As. Arsenic, TiO2, Th, Al2O3, Bi, La, Ga, Ni, and V are high in mullite, and the magnetic matter is enriched in Fe2O3, CaO, MnO, TiO2, Cs, Co, As, Cd, Ba, Ni, Sb, MgO, Zn, and V. The remaining elements are high in the glass fraction. The concentration of K2O, Na2O, P2O5, Nb, Cr, Ta, U, W, Rb, and Ni do not clearly vary with particle size, while SiO2 and Hg decrease and the remaining elements clearly increase with decreasing particle size. ?? 2009 Elsevier B.V.

Dai, S.; Zhao, L.; Peng, S.; Chou, C.-L.; Wang, X.; Zhang, Y.; Li, D.; Sun, Y.

2010-01-01

242

Mineralogy, geochemistry and genesis of the modern sediments of Seyfe Lake, K?r?ehir, central Anatolia, Turkey  

NASA Astrophysics Data System (ADS)

Seyfe Lake (K?r?ehir, Turkey) is located within a depression zone extending along a NW-SE-trending fault in central Anatolia. Evaporite and carbonate sediments occur at the bottom of the lake which is fed by high-sulfate spring and well waters circulating N-S through salt domes. The recent sediments of Seyfe Lake are deposited in delta, backshore, beach, mud-flat and shallow lake environments. In the mud-flat environment, calcite, gypsum, halite, and thenardite are associated with fine-grained detrital sediments. Sediments from the margin to the lake center are distributed as calcite, gypsum and halite ± thenardite, yielding an annular distribution pattern. An increase in Na2O, SO3, and S, and a decrease in CaO toward the lake center are due to sediment distribution. On the other hand, a positive correlation of SiO2 with MgO, K2O, Na2O, Al2O3, and Fe2O3 + TiO2 is attributed to the presence of smectite, illite and feldspar. In addition, a positive correlation of Sr and Ba with CaO is related to the amount of gypsum in the sediments. Strontium is associated with in situ gypsum crystals; it increases in the intermediate and central zones of the lake as a result of a relative increase in salinity toward the lake center. The association of Sr with gypsum in the sediments suggests that Ca and Sr were derived from Sr-bearing evaporites and their carbonate host rocks, which were the likely aquifers for the brine. The S- and O-isotopic compositions of sulfate crystals range from +19.1‰ to +21.7‰ and from +16.9‰ to +20.9‰ SMOW, respectively, suggesting precipitation in a closed lake system. A relative increase of oxygen and sulfur isotope ratios toward the lake center suggests dissolution of gypsum in the host rock, with contributions from circulating groundwater and sulfate reduction (possibly by bacterial reduction). 87Sr/86Sr isotope ratios range from 0.707286 to 0.707879, suggesting a non-marine Oligo-Pliocene evaporitic host rock source for precipitation in Seyfe Lake. The concentration of Sr- and S-isotope ratios in the gypsum crystals indicates formation by precipitation/recrystallization from brine rather than from seawater.

Önalgil, Nergis; Kadir, Selahattin; Külah, Tacit; Eren, Muhsin; Gürel, Ali

2015-02-01

243

Silicate melt inclusions in clinopyroxene phenocrysts from mafic dikes in the eastern North China Craton: Constraints on melt evolution  

NASA Astrophysics Data System (ADS)

Silicate melt inclusions (SMIs) in magmatic minerals provide key information on the chemical and mineralogical evolution of source magmas. The widespread Cretaceous mafic dikes in the Jiaojia region of the eastern North China Craton contain abundant SMIs within clinopyroxene phenocrysts. The daughter minerals in these SMIs include amphibole, plagioclase, pyrite and ilmenite, together with CO2 + CH4 and CH4 as the major volatile phase. The total homogenization temperatures of the SMIs range between 1280 and 1300 °C. The host clinopyroxene phenocrysts in these dolerite dikes are dominantly augite with minor diopside. From LA-ICPMS analyses of the SMIs, we identify two compositional groups: (1) low-MgO (6.0-7.6 wt.%) SMIs and (2) high-MgO (11.2-13.9 wt.%) SMIs. The Low-MgO group exhibits higher concentrations of TiO2, Al2O3, Na2O, P2O5 and lower CaO and CaO/Al2O3 ratio as compared to the high-MgO SMIs. The trace element patterns of the two types of SMIs are similar to those of the host mafic dikes. However, the low-MgO SMIs and host mafic dikes are clearly more enriched in all the trace elements as compared to the high-MgO type, especially with regard to the highly incompatible elements. The estimated capture temperatures and pressures are 1351-1400 °C and 1.6-2.1 GPa for the high-MgO SMIs and 1177-1215 °C and 0.6-1.1GPa for the low-MgO type. The high-MgO and low-MgO SMIs were trapped at depths of ?51-68 km and ?20-35 km, respectively. Computations show that the parental melt is mafic with SiO2 content 49.6 wt% and Mg# 80.0 with relatively low total alkali contents (1.35 wt% Na2O + K2O) and high CaO (15.2 wt%). Exploratory runs with the program MELTS and pMELTS show that the low-MgO and high-MgO SMIs were derived from the same parental melt through different degrees of crystallization. Clinopyroxene and a small amount of olivine were the fractionating phases during the evolution from parental melts to high MgO melts, while the low MgO melts experienced significant fractional crystallization of olivine and clinopyroxene. We postulate the newly accreted lithospheric clinopyroxenite as the major source for the Jiaojia dolerite dikes, with melting of the source at a depth of ?68-80 km.

Cai, Ya-Chun; Fan, Hong-Rui; Santosh, M.; Hu, Fang-Fang; Yang, Kui-Feng; Liu, Xuan; Liu, Yongsheng

2015-01-01

244

[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

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

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

2014-05-01

245

Synthesis of SiO? and CaO rich calcium silicate systems via sol-gel process: bioactivity, biocompatibility, and drug delivery tests.  

PubMed

Silica and calcium silicate amorphous materials, mixed with sodium ampicillin, a broad-spectrum antibiotic, have been synthesized by sol-gel method. The amorphous nature of the gels was ascertained by X-ray diffraction analysis. The bioactivity of the synthesized materials has been put into evidence by the appearance of a crystal of hydroxyapatite on the surface of the samples soaked in a fluid simulating the composition of the human blood plasma, as detected through FTIR measurements and SEM micrographs. The present work refers to a series of in-vitro biocompatibility tests, which has been performed on silicate and CaO rich calcium silicate gel-glasses, to study the cell behavior when seeded on 1 cm(2) material fragments, introduced into an in-vitro culture system. 3T3 cell lines have been used and the viability has been evaluated by WST-8 test. The composition of the adopted glasses can be expressed by the following general formula: x CaO• (1?-?x) SiO2 with x?=?0.00; 0.30; 0.40; 0.50; 0.60. Subsequently, release kinetics in a simulate body fluid (SBF) has been investigated. The amount of sodium ampicillin released has been detected by UV-Vis spectroscopy. The release kinetics has appeared to occur in more than one stage. All data have shown that those materials could be used as drug delivery bioactive systems. PMID:24123774

Catauro, M; Papale, F; Roviello, G; Ferone, C; Bollino, F; Trifuoggi, M; Aurilio, C

2014-09-01

246

The effects of Mn2+ doping on the luminescence properties of 12CaO 7Al2O:Eu2+ nanocrystal phosphor.  

PubMed

The long lasting blue phosphorescence (LLP) and photostimulated luminescence (PSL) after ultraviolet light irradiation at room temperature in 12CaO 7Al2O3:xEu2+, yMn2+ (x = 0, 0.001; y = 0, 0.01) prepared by the chemical co-precipitation method were observed. It was shown that novel oxide 12CaO 7Al2O3:Eu2+, Mn2+ (C12A7:Eu2+, Mn2+) with unique nanocage structure can store energy when irradiated with 365 nm photons. And photon energy can be subsequently released by exposed to 980 nm light. The codopant Mn2+ enhances the intensity of the persistent phosphorescence and PSL due to the existence of more shallow and new deeper electron traps in C12A7: Eu2+, Mn2+. A model for energy storing and recovering and the detailed mechanism of PSL are presented through comparing with the luminescence properties of the co-doped C12A7:Eu2+, Mn2+ and C12A7:Eu2+. PMID:22413331

Yan, X L; Liu, Y X; Yan, D T; Zhu, H C; Liu, C G; Xu, C S

2011-11-01

247

Petrogenesis of syntectonic granites emplaced at the transition from thrusting to transcurrent tectonics in post-collisional setting: Whole-rock and Sr-Nd-Pb isotope geochemistry in the Neoproterozoic Quatro Ilhas and Mariscal Granites, Southern Brazil  

NASA Astrophysics Data System (ADS)

The Neoproterozoic post-collisional period in southern Brazil (650-580 Ma) is characterized by substantial volumes of magma emplaced along the active shear zones that compose the Southern Brazilian Shear Belt. The early-phase syntectonic magmatism (630-610 Ma) is represented by the porphyritic, high-K, metaluminous to peraluminous Quatro Ilhas Granitoids and the younger heterogranular, slightly peraluminous Mariscal Granite. Quatro Ilhas Granitoids include three main petrographic varieties (muscovite-biotite granodiorite — mbg; biotite monzogranite — bmz; and leucogranite — lcg) that, although sharing some significant geochemical characteristics, are not strictly comagmatic, as shown by chemical and Sr-Nd-Pb isotope data. The most primitive muscovite-biotite granodiorite was produced by contamination of more mafic melts (possibly with some mantle component) with peraluminous crustal melts; the biotite monzogranite, although more felsic, has higher Ca, MgO, TiO2 and Ba, and lower K2O, FeOt, Sr and Rb contents, possibly reflecting some mixing with coeval mafic magmas of tholeiitic affinity; the leucogranite may be derived from pure crustal melts. The Mariscal Granite is formed by two main granite types which occur intimately associated in the same pluton, one with higher K (5-6.5 wt.% K2O) high Rb and lower CaO, Na2O, Ba and Zr as compared to the other (3-5 wt.% of K2O). The two Mariscal Granite varieties have compositional correspondence with fine-grained granites (fgg) that occur as tabular bodies which intruded the Quatro Ilhas Granoitoids before they were fully crystallized, and are inferred to correspond to the Mariscal Granite feeders, an interpretation that is reinforced by similar U-Pb zircon crystallization ages. The initial evolution of the post-collisional magmatism, marked by the emplacement of the Quatro Ilhas Granitoids varieties, activated sources that produced mantle and crustal magmas whose emplacement was controlled both by flat-lying and transcurrent structures. The transition from thrust to transcurrent-related tectonics coincides with the increase in the proportion of crustal-derived melts. The transcurrent tectonics seems to have played an essential role in the generation of mantle-derived magmas and may have facilitated their interaction with crustal melts which seem to be to a large extent the products of reworking of orthogneiss protoliths.

Florisbal, Luana Moreira; Bitencourt, Maria de Fátima; Janasi, Valdecir de Assis; Nardi, Lauro Valentim Stoll; Heaman, Larry M.

2012-11-01

248

Geochronological and geochemical constraints on the petrogenesis of the early Paleoproterozoic potassic granite in the Lushan area, southern margin of the North China Craton  

NASA Astrophysics Data System (ADS)

We conducted a geochronological and geochemical study on the Paleoproterozoic potassic granites in the Lushan area, southern margin of the North China Craton (NCC) to understand the tectonic regime of the NCC at 2.2-2.1 Ga. This rock suite formed at 2194 ± 29 Ma. The rocks are rich in SiO2 (76.10-77.73 wt.%), and K2O (5.94-6.90 wt.%) with high K2O + Na2O contents from 7.56 wt.% to 8.48 wt.%, but poor in CaO (0.10-0.28 wt.%), P2O5 (0.02-0.05 wt.%) and MgO (0.01-0.30 wt.%, Mg# = 1.08-27.3), indicating they experienced fractional crystallization. Major element compositions suggest the potassic granites share an affinity with high K calc-alkaline granite. Even though the Lushan potassic granitic rocks have high A/CNK ratios (1.11-1.25), which can reach peraluminous feature, the very low P2O5 contents and negative correlation of P2O5 and SiO2 ruling out they are S-type granites. Different from peralkaline A-type granites, the Lushan potassic granites have variable Zr concentrations (160-344 ppm, 226 ppm on average) and 10,000 Ga/Al ratios (1.76-3.00), together with high zircon saturation temperatures (TZr = 826-885 °C), indicating they are fractionated aluminous A-type granites. Enriched LREE ((La/Yb)N = 9.72-81.8), negative Eu anomalies, and low Sr/Y with no correlations in Sr/Y and Sr/Zr versus CaO suggest the possible presence of Ca-rich plagioclase and absence of garnet in the residual. Magmatic zircon grains have variable ?Hf(t) values (-2.4 to +7.3) with zircon two-stage Hf model ages (TDMC) varying from 2848 Ma to 2306 Ma (mostly around ca. 2.5 Ga), and are plotted in the evolution line of crustal felsic rock. We propose that the rocks mainly formed by partial melting of ca. 2.50 Ga tonalitic-granodioritic crust as a result of upwelling mantle-derived magmas which provided thermal flux and source materials in an intra-continent rifting. The ca. 2.2 Ga magmatism suggests that intra-continental rifting occurred at 2.35-1.97 Ga at least in the southern margin of the NCC after its final cratonization in the late Neoarchean.

Zhou, Yanyan; Zhai, Mingguo; Zhao, Taiping; Lan, Zhongwu; Sun, Qianying

2014-11-01

249

Petrogenesis of Triassic granites from the Nanling Range in South China: Implications for geochemical diversity in granites  

NASA Astrophysics Data System (ADS)

A combined study of whole-rock major-trace elements and Sr-Nd isotopes, zircon U-Pb ages, Hf and O isotopes as well as biotite geochemistry was carried out for Triassic granite intrusions from the Nanling Range in South China. The results provide insights into the effects of source composition and melting conditions on the geochemical diversity of granites. The granites of interest are peraluminous, and contain primary muscovite and tourmaline. They are characterized by high zircon ?18O values of > 9.0‰, high initial 87Sr/86Sr values of ~ 0.7200, and homogeneous ?Nd(t) values of - 11.3 to - 9.8, as well as variable zircon ?Hf(t) values of - 12.2 to - 5.8. Biotite geochemistry is similar to that of common peraluminous granites. An integrated interpretation of these petrological, mineralogical and geochemical data indicates that these granites were derived from partial melting of metasedimentary rocks under variable physicochemical conditions. The differences in whole-rock and biotite geochemistry between the intrusions are ascribed to the variable effects of source heterogeneity and melting temperature. The Luxi intrusion exhibits higher contents of MgO, FeOT, TiO2 and CaO than common melts derived from metasedimentary rocks, tight variations in major-trace elements and homogeneous Sr-Nd isotopic compositions, and homogeneous biotite composition with high Mg# [= Mg / (Mg + Fe) in molar] and lower whole-rock A/CNK values [= Al2O3 / (CaO + Na2O + K2O) in molar]. These can be explained by originating from a relatively mafic metasedimentary source. On the other hand, the geochemical diversity of granites can be caused by the difference in melting temperature in addition to the source heterogeneity. This is suggested by the Xiazhuang and Fucheng intrusions which exhibit similar range of SiO2. Nevertheless, the Fucheng intrusion is ferroan, and high in TiO2, (Na2O + K2O)/CaO, TiO2/MgO, Ga/Al and Zr + Nb + Ce + Y, but low in CaO, MgO and Mg#. Most of its major elements and their ratios are similar to those of A-type granites that were generated from F-rich rocks at high temperatures, consistent with the enrichment of Fe and F in its biotite. Thus, partial melting of a metasedimentary restite at reduced conditions after previous melt extraction is suggested to produce the geochemical feature of A-type granites in the Fucheng intrusion. In contrast, partial melting of fertile metasedimentary rocks would produce normal S-type granites like the Xiazhuang intrusion, with its geochemical variations ascrible to source heterogeneity and differential melting. Therefore, the geochemical composition of granites is primarily dictated by the composition of source rocks in addition to the physicochemical conditions of partial melting.

Gao, Peng; Zhao, Zi-Fu; Zheng, Yong-Fei

2014-12-01

250

Conditions of crystallization of the Ural platinum-bearing ultrabasic massifs: evidence from melt inclusions  

NASA Astrophysics Data System (ADS)

Conditions of the Ural platinum-bearing ultramafic massifs formation attract attention of numerous researchers. A most important peculiarity of such plutons is their dunite cores, to which commercial Pt deposits are related. There are a different opinions about genesis of these massifs and usual methods not always can solve this question. As a result of melt inclusions study in the Cr-spinel the new data on physical and chemical parameters of dunite crystallization of the Nizhnii Tagil platinum-bearing ulrabasic massif (Ural) was obtained. The comparative analysis of Cr-spinels, containing melt inclusions, has shown essential differences of these minerals from chromites of the ultrabasic ophiolite complexes and of modern oceanic crust. Contents of major chemical components in the heated and quenched melt inclusions are close to those in the picrite and this testifies dunite crystallization from ultrabasic (to 24 wt.% MgO) magma. On the variation diagrams for inclusions in Cr-spinel the following changes of chemical compositions are established: during SiO2 growth there is falling of FeO, MgO, and increase of CaO, Na2O contents. Values of TiO2, Al2O3, K2O and P2O5 remain as a whole constant. Comparing to the data on the melt inclusions in Cr-spinel from the Konder massif, we see that values of the most part of chemical components (SiO2, TiO2, K2O, P2O5) are actually overlapped. At the same time, for the Nizhnii Tagil platinum-bearing massif the big maintenances of FeO and CaO in inclusions are marked. Distinct dependence of the majority of components from the MgO content in inclusions is observed: values TiO2, Al2O3 FeO, CaO and Na2O fall at transition to more magnesia melts. On the peculiarities of distribution of petrochemical characteristics melt inclusions in considered Cr-spinels are co-ordinated with the data on evolution of compositions of melts and rocks of model stratified ultramafic plutons during their crystallization in the magmatic chambers. On the diagrams an association of melt inclusions with the data on inclusions in Cr-spinels from the Konder platinum-bearing and Karashat ophiolite massifs is clearly visible. Our computer simulations on the basis of melt inclusion compositions by the PETROLOG program package (Danyushevsky, Plechov, 2011) allowed to evaluate the crystallization temperature of dunites of the Nizhnii Tagil platinum-bearing massif in the intrusive chamber. The most part of olivine was formed from 1430 to 1360°C and continued to crystallize until to 1280°C. Cr-spinel crystallized from melts in the range of temperatures from 1345 to 1310°C. The investigations were supported by the Russian Foundation for Basic Research (project No 12-05-00959) and by Projects N 2.1 and N 50.

Simonov, Vladimir; Puchkov, Victor; Prikhod'ko, Vladimir; Stupakov, Sergey; Kotlyarov, Alexey

2013-04-01

251

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

NASA Astrophysics Data System (ADS)

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.

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

2015-04-01

252

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

Role of polaron hopping in leakage current behavior of a SrTiO3 single crystal Y. Cao, S increasing leakage currents under dc field stress, followed by a rapid increase of currents indicating://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

Chen, Long-Qing

253

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

Role of polaron hopping in leakage current behavior of a SrTiO3 single crystal Y. Cao, S increasing leakage currents under dc field stress, followed by a rapid increase of currents indicating://scitation.aip.org/termsconditions. Downloaded to ] IP: 128.210.4.213 On: Fri, 14 Mar 2014 13:47:27 #12;Role of polaron hopping in leakage

Shen, Jie

254

Liu, Z., H.C. Frey, Y. Cao, and B. Deshpande, "Modeling of In-vehicle PM2.5 Exposure Using the Stochastic Human Exposure and Dose Simulation Model," Paper 2009-A-238-AWMA, Proceedings, 102nd  

E-print Network

Liu, Z., H.C. Frey, Y. Cao, and B. Deshpande, "Modeling of In-vehicle PM2.5 Exposure Using of In-vehicle PM2.5 Exposure Using the Stochastic Human Exposure and Dose Simulation Model Paper: 2009-A Factors that influence in-vehicle PM2.5 exposure are indentified and assessed. The methodology used

Frey, H. Christopher

255

Deshpande, B., H.C. Frey, Y. Cao, and Z. Liu, "Modeling of the Penetration of Ambient PM2.5 to Indoor Residential Microenvironment," Paper 2009-A-86-AWMA, Proceedings, 102nd Annual Conference and Exhibition, Air & Waste  

E-print Network

Deshpande, B., H.C. Frey, Y. Cao, and Z. Liu, "Modeling of the Penetration of Ambient PM2.5 of the Penetration of Ambient PM2.5 to Indoor Residential Microenvironment Paper: 2009-A-86-AWMA Bela K. Deshpande, H have demonstrated a positive relationship between ambient fine particulate matter (PM2.5) and adverse

Frey, H. Christopher

256

Constant threshold resistivity in the metal-insulator transition of VO2 J. Cao,1,2 W. Fan,1,3 K. Chen,4 N. Tamura,4 M. Kunz,4 V. Eyert,5 and J. Wu1,2,*  

E-print Network

Constant threshold resistivity in the metal-insulator transition of VO2 J. Cao,1,2 W. Fan,1,3 K it transfers into the metallic phase, regardless of the initial resistivity, transition temperature, and strain-electron concentration is needed on the insulating side to trigger the insulator-to-metal transition, indicating

Wu, Junqiao

257

Est. Date Operation Product Rate Comments N P2O5 K2O Ca S 10/14 Paratill  

E-print Network

.3 qt 5/20 Fertilizer Air Flow 21-0-0 150 watered in 31 6/5 Post Herbicide Program if needed varies Air Flow 46-0-0 350 split 100lb, 250lb, watered in. 161 10/10 Harvest Researcher responsible gpa 4/1 Broadcast with Airflow 0-0-60 Potash 350 lb Rate depends on soil test 210 4/1 Broadcast

258

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

PubMed

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

Zheng, Jinsheng

2014-03-01

259

Performance of CaO and MgO for the hot gas clean up in gasification of a chlorine-containing (RDF) feedstock.  

PubMed

Calcined limestone (CaO) and calcined dolomite (CaO.MgO) were tested at bench scale to study their usefulness in cleaning hot raw gas from a fluidized bed gasifier of a synthetic or simulated refuse-derived fuel (RDF) with a high (3 wt%) content in chlorine. In the gas cleaning reactor two main reactions occurred simultaneously: the elimination of HCl and the elimination of tar by steam reforming. The elimination of HCl formed CaCl2 and MgCl2 with melting points below the high (above 800 degrees C) temperatures required for the simultaneous tar elimination reaction. So, the CaO-based particles progressively melted and the catalytic gas cleaning reactor became a compact, agglomerated or glued, cake. Therefore, the life and usefulness of the CaO-based solids used was very low. Nevertheless, and to further avoid these problems, some positive guidelines for future research are proposed here. PMID:18372172

Corella, José; Toledo, José M; Molina, Gregorio

2008-11-01

260

Photoinduced generation of electron anions in H-doped nanoporous oxide 12CaO•7Al2O3: Toward an optically controlled formation of electrides  

NASA Astrophysics Data System (ADS)

We suggest, on the basis of detailed ab initio calculations of both ground and photoexcited states of H-doped 12CaO•7Al2O3 (C12A7:H), that stable high-conductivity regions can be optically generated in this insulating system. Each H- ion in C12A7:H can, under photoirradiation at 3.8-4.5 eV, produce up to two electrons and a proton that binds to the lattice network and forms OH-. Mobile electrons play a role of anions in this system. They move over subnanosized cages of the C12A7 lattice via polaron hopping. The insulating state is reversibly restored upon heating to 300 °C.

Sushko, Peter V.; Shluger, Alexander L.; Hayashi, Katsuro; Hirano, Masahiro; Hosono, Hideo

2005-02-01

261

Effect of H2O on NO Reduction over NSR Catalyst 12CaO·7Al2O3/10%K  

NASA Astrophysics Data System (ADS)

A novel NOx storage/reduction catalyst 12CaO·7Al2O3/10%K, defined as C12A7/K, was prepared, which possesses good NOx storage/reduction ability with a high sulfur-tolerance. The effect of H2O on the NO reduction features over the C12A7/K catalyst was investigated. The NO conversion and the N2 selectivity were measured as a function of temperature and H2O concentration. In the presence of 1.2% H2O, both the NO conversion and the N2 selectivity significantly decrease at lower temperature region (< 500°C). At temperatures over 500°C, however, the NO reduction is only slightly influenced by H2O. The species of NO3-/NO2- are confirmed as main storage components in the C12A7/K catalyst, which are further reduced into N2 by H2 under the reduction conditions.

Gao, Ai-mei; Wang, Hua-jing; Tu, Jing; Li, Quan-xin

2006-12-01

262

Generation of negative ions in the gas phase from a 12CaO.7Al2O3 membrane-coated ceramic heater under atmospheric pressure  

NASA Astrophysics Data System (ADS)

12CaO?7Al2O3 (C12A7) crystal is able to generate strong and high purity oxygen anion (O-) beam under reduced pressure. However, the emission of O- or related species under atmospheric pressure has not been evaluated. In this study, the characteristics of negative ion species emissions from the C12A7 membrane-coated ceramic heater under atmospheric pressure were investigated by quadrupole mass spectrometer. Negative ion species were confirmed to be emitted even under atmospheric pressure. It was supposed that the detected negative ion clusters, such as O-(H2O)n, O2-(H2O)n, and CO4-(H2O)n, were generated by the reaction of negative ions emitted from the heater with impurities in He gas.

Yamamoto, Mitsuo; Shima, Akio; Nishioka, Masateru; Sadakata, Masayoshi

2008-12-01

263

Evidence for Bardeen-Cooper-Schrieffer-type superconducting behavior in the electride (CaO)12(Al2O3)7:e- from heat capacity measurements  

NASA Astrophysics Data System (ADS)

The heat capacity of the single crystalline electride of (CaO)12(Al2O3)7:e- (C12A7:e-) with Tc=0.2K was larger than that of electron-undoped C12A7 in the temperature range 0.085-5K , reflecting the metallic nature of the electride. A superconducting transition was detected as a heat capacity jump ?Cp=3.4mJmol-1K-1 , and the profile and magnitude of ?Cp agreed well with those expected from the BCS theory. The electron-phonon coupling constant (?˜0.46) and Debye temperature (?D˜630K) were much larger than those for alkali metals having s -like conduction electrons as in the present electride, suggesting that electrides having a rigid structure will be a class of BCS superconductors.

Kohama, Yoshimitsu; Kim, Sung Wng; Tojo, Takeo; Kawaji, Hitoshi; Atake, Tooru; Matsuishi, Satoru; Hosono, Hideo

2008-03-01

264

Electronic insulator-conductor conversion in hydride ion-doped 12CaO•7Al2O3 by electron-beam irradiation  

NASA Astrophysics Data System (ADS)

We report formation of persistent carrier electrons in hydride ion (H-)-incorporated 12CaO•7Al2O3 (C12A7) by electron-beam irradiation. The electrical conductivity of H--doped C12A7 single crystals increases with the electron-beam irradiation dose, accompanied with a green coloration attributable to a carrier electron formation. A 25 keV electron beam with a dose of ˜500?Ccm-2 fully converts the conductivity in surface layers to the depth of ˜4?m. Carrier electron formation is most likely due to electron-hole pairs generated in the electron excitation volume and subsequent energy transfer to the H- ions. The estimated carrier formation yield per an incident electron is ˜30. These findings may enable a fine patterning of the conductive area without photomasks and photoresists.

Hayashi, Katsuro; Toda, Yoshitake; Kamiya, Toshio; Hirano, Masahiro; Yamanaka, Minako; Tanaka, Isao; Yamamoto, Takahisa; Hosono, Hideo

2005-01-01

265

On the magnetic and spectroscopic properties of high-valent Mn3CaO4 cubanes as structural units of natural and artificial water-oxidizing catalysts.  

PubMed

The Mn(IV)3CaO4 cubane is a structural motif present in the oxygen-evolving complex (OEC) of photosystem II and in water-oxidizing Mn/Ca layered oxides. This work investigates the magnetic and spectroscopic properties of two recently synthesized complexes and a series of idealized models that incorporate this structural unit. Magnetic interactions, accessible spin states, and (55)Mn isotropic hyperfine couplings are computed with quantum chemical methods and form the basis for structure-property correlations. Additionally, the effects of oxo-bridge protonation and one-electron reduction are examined. The calculated properties are found to be in excellent agreement with available experimental data. It is established that all synthetic and model Mn(IV)3CaO4 cubane complexes have the same high-spin S = (9)/2 ground state. The magnetic coupling conditions under which different ground spin states can be accessed are determined. Substitution of Mn(IV) magnetic centers by diamagnetic ions [e.g., Ge(IV)] allows one to "switch off" specific spin sites in order to examine the magnetic orbitals along individual Mn-Mn exchange pathways, which confirms the predominance of ferromagnetic interactions within the cubane framework. The span of the Heisenberg spin ladder is found to correlate inversely with the number of protonated oxo bridges. Energetic comparisons for protonated models show that the tris-?-oxo bridge connecting only Mn ions in the cubane has the lowest proton affinity and that the average relaxation energy per additional proton is on the order of 18 kcal·mol(-1), thus making access to ground states other than the high-spin S = (9)/2 state in these cubanes unlikely. The relevance of these cubanes for the OEC and synthetic oxides is discussed. PMID:23527603

Krewald, Vera; Neese, Frank; Pantazis, Dimitrios A

2013-04-17

266

Phase equilibria and crystal chemistry of the CaO-1/2 >Nd2O3-CoOz system at 885 °C in air  

NASA Astrophysics Data System (ADS)

The phase diagram of the CaO-1/2 >Nd2O3-CoOz 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, (Ca3-xNdx)Co4O9-z (0?x?0.5), which has a misfit layered structure, and Ca3Co2O6 which consists of 1D chains of alternating CoO6 trigonal prisms and CoO6 octahedra. Ca3Co2O6 was found to be a point compound without the substitution of Nd on the Ca site. The reported Nd2CoO4 phase was not observed at 885 °C. A ternary (Ca1-xNd1+x)CoO4-z (x=0) phase, or (CaNdCo)O4-z, was found to be stable at this temperature. A solid solution region of distorted perovskite (Nd1-xCax)CoO3-z (0?x?0.25, space group Pnma) was established. In the peripheral binary systems, while a solid solution region was identified for (Nd1-xCax)2O3-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-Nd2O3-CoOz system in air.

Wong-Ng, W.; Laws, W.; Talley, K. R.; Huang, Q.; Yan, Y.; Martin, J.; Kaduk, J. A.

2014-07-01

267

Raman Study of xMeO · (100-x)[P2O5 · CaO] (MeO=Fe2O3, V2O5 or (Fe2O3 · V2O5)) Glass Systems  

NASA Astrophysics Data System (ADS)

Glasses from xMeO · (100-x)[P2O5 · CaO], (MeO=Fe2O3, V2O5 or (Fe2O3 · V2O5)) were prepared and investigated using Raman scattering spectroscopy, over compositional range x=0-50% mol. The influence of Fe2O3, V2O5 or (Fe2O3·V2O5) content on the structure of P2O5·CaO glass matrix was followed. The addition of Fe2O3, V2O5 or (Fe2O3·V2O5) determines the modification of the structure of the studied glasses. The Raman spectra of xFe2O3(100-x)[P2O5·CaO] do not present any absorption bands characteristic to Fe2O3 but its evolution is dependent on the iron content. The Raman spectra of xV2O5·(100-x)[P2O5·CaO] present, besides the bands specific for the matrix, some bands assigned to characteristic vibrations of V-O bonds which are evidenced only for high content of V2O5. The evolution of the spectra is dependent on V2O5 content. The Raman spectra of x(Fe2O3·V2O5)·(100-x)[P2O5·CaO] system showed that phosphate units are the main structural units of the glass system, iron and vanadium ions are located in the network. The increasing of iron and vanadium content indicate a gradual decrease in the number of bridging oxygen ions and an increase in the number of non-bridging oxygen ions.

Andronache, Constantin

268

End-member fluids for diamond formation and their possible sources  

NASA Astrophysics Data System (ADS)

Microinclusions in fibrous diamonds carry high density fluids (HDF) with compositions that vary between silicic, carbonatitic and saline end-members. Combining EPMA and FTIR data we can estimate the composition of each end-member. The silicic end-member composition (Udachnaya) comprises ~90 wt% silicates, 4% carbonate, 4% water and minor apatite. The saline end-member (Diavik, Canada) carries 51 wt% alkali halides, 12% carbonates and 37% water. Klein-BenDavid et al. (in review) defined two carbonatitic end-members. The low-Mg one carries ~75 wt% carbonates, 11% silicates, 5% halides, 2% apatite and 7% water; the high-Mg end-member carries similar proportions, except for the higher apatite: 78% carbonates, 9% silicates, 5% apatite, 2% halides and 6% water, but with much higher Mg/(Mg+Fe+Ca) ratio. The volatile-free oxides proportions of the most silicic microinclusions in an Udachnaya diamond are: 69 wt% SiO2; 14% Al2O3; 10% K2O, 2% Na2O, 1% CaO and P2O5 and minor FeO, TiO2, MgO, and Cl. The saline HDF carries 73 wt% KCl, 12% NaCl, 7% CaO, 2.5% MgO, 2.5% BaO, 1.5% FeO and 1.5% SiO2. In the low-Mg carbonatitic HDF calcium exceeds magnesium: ~21 wt% CaO, 18% FeO, 12% MgO, 22% K2O; 10% SiO2, 8% Na2O and minor TiO2, Al2O3, P2O5 and Cl, while in the high-Mg end-member MgO is the main oxide: ~29% MgO, 23% CaO, 7% FeO, 17% K2O, 8% SiO2, 9% Na2O, 2% P2O5 and Cl and minor BaO, TiO2, Cr2O3 and Al2O3 ( all values were calculated on volatile-free basis). Weiss et al., in a companion abstract, suggest that the four end-members form two arrays; one between the saline and the high-Mg carbonatitic compositions and the second between the silicic and the low-Mg carbonatitic ones. They further suggest that the first array represents a process that takes place in a peridotitic environment and the other in an eclogitic one. For example, the arrays may be formed by interaction of hydrous or saline fluids with carbonate-eclogite or with carbonate-peridotite. Safonov et al. (2007) suggested that a saline melt can interact with silicate minerals to form immiscible silicic melt that may later evolve into a carbonatitic HDF. In an ultramafic environment a saline melt may evolve along the array to high-Mg carbonatites without forming an immiscible silicate melt (Safonov, 2008). The source of the saline fluid is not clear. It may be present as discrete halides or as a grain-boundary phase in the carbonate-bearing rock, or it may form deeper in the mantle and migrate upwards either as a saline melt, or as a hydrous fluid that is concentrated enough to preclude interaction with the mantle rocks it traverses. A second alternative is to introduce the carbonate as the penetrating fluid in the form of carbonatitic melt. A third alternative involves the upward migration of CH4 and heavier hydrocarbons. Such a fluid should be stable in eclogitic or peridotitic environments, as long as the oxygen fugacity is low enough. During ascent, such fluids migrate to more oxidized regions and eventually will react with the mantle rocks to form C+H2O (Luth, 1993; Malkovets et al. 2007) and later CO2. In eclogitic rocks, the water will react to form a silicic HDF and the C may precipitate as diamond. In a peridotitic environment, at temperatures below the carbonate solidus, such water may leach and dissolve K and Cl from the rock and evolve into a saline HDF. Temperature increase or further diamond oxidation may initiate the formation of carbonatitic HDF's.

Navon, O.; Weiss, Y.; Klein-Bendavid, O.; Bell, D. R.

2009-04-01

269

Bimodal Silurian and Lower Devonian volcanic rock assemblages in the Machias-Eastport area, Maine  

USGS Publications Warehouse

Exposed in the Machias-Eastport area of southeastern Maine is the thickest (at least 8,000 m), best exposed, best dated, and most nearly complete succession of Silurian and Lower Devonian volcanic strata in the coastal volcanic belt, remnants of which crop out along the coasts of southern New Brunswick, Canada, and southeastern New England in the United States. The volcanics were erupted through the 600-700-million-year-old Avalonian sialic basement. To test the possibility that this volcanic belt was a magmatic arc above a subduction zone prior to presumed Acadian continental collision, samples representing the entire section in the Machias-Eastport area of Maine were chemically analyzed. Three strongly bimodal assemblages of volcanic rocks and associated intrusives are recognized, herein called the Silurian, older Devonian, and younger Devonian assemblages. The Silurian assemblage contains typically nonporphyritic high-alumina tholeiitic basalts, basaltic andesites, and diabase of continental characterand calc-alkalic rhyolites, silicic dacites, and one known dike of andesite. These rocks are associated with fossiliferous, predominantly marine strata of the Quoddy, Dennys, and Edmunds Formations, and the Leighton Formation of the Pembroke Group (the stratigraphic rank of both is revised herein for the Machias-Eastport area), all of Silurian age. The shallow marine Hersey Formation (stratigraphic rank also revised herein) of the Pembroke Group, of latest Silurian age (and possibly earliest Devonian, as suggested by an ostracode fauna), contains no known volcanics; and it evidently was deposited during a volcanic hiatus that immediately preceded emergence of the coastal volcanic belt and the eruption of the older Devonian assemblage. The older Devonian assemblage, in the lagoonal to subaerial Lower Devonian Eastport Formation, contains tholeiitic basalts and basaltic andesites, typically with abundant plagioclase phenocrysts and typically richer in iron and titanium and poorer in magnesium and nickel than the Silurian basalts; and the Eastport Formation has rhyolites and silicic dacites that have higher average SiO2 and K2O contents and higher ratios of FeO* to MgO than the Silurian ones. The younger Devonian assemblage is represented by one sample of basalt from a flow in red beds of the post-Acadian Upper Devonian Perry Formation, and by three samples from pre-Acadian diabases that intrude the Leighton and Hersey Formations. These rocks are even richer in titanium and iron and poorer in magnesium and nickel than the older Devonian basalts. Post-Acadian granitic plutons exposed along the coastal belt for which analyses are available are tentatively included in the younger Devonian assemblage. The most conspicuous features of the coastal volcanics and associated intrusives are the preponderance of rocks of basaltic composition ( < 52 percent SiO2 ) in the Silurian assemblage, and the near absence in all assemblages of intermediate rocks having 57-67 percent SiO2 (calculated without volatiles). All the rocks are variably altered spilites and keratophyres. The basaltic types are adequately defined, however, by eight samples of least altered basalts having calcic plagioclase, clinopyroxene, and 0.5 percent or less CO2 , The more altered basalts are variably enriched or depleted in Na2O, K2O, and CaO relative to the least altered ones. In the silicic rocks no primary ferromagnesian minerals are preserved. The Na2O and K2O contents of the silicic rocks are erratic; they are approximately reciprocal, possibly owing to alkali exchange while the rocks were still glassy. We propose that the coastal volcanic belt extended along an axis of thermal swelling in the Earth's mantle and upward intrusion of partially melted mantle into the sialic Avalonian crust. These processes were accompanied by shoaling and emergence of the belt, and they produced the bimodal volcanism. Tholeiitic basaltic melts segregated from mantle material

Gates, Olcott; Moench, R.H.

1981-01-01

270

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

NASA Astrophysics Data System (ADS)

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.

Villares, F. M.

2013-05-01

271

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)

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.

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

2013-06-01

272

Oxidized, magnetite-series, rapakivi-type granites of Carajás, Brazil: Implications for classification and petrogenesis of A-type granites  

NASA Astrophysics Data System (ADS)

The varying geochemical and petrogenetic nature of A-type granites is a controversial issue. The oxidized, magnetite-series A-type granites, defined by Anderson and Bender [Anderson, J.L., Bender, E.E., 1989. Nature and origin of Proterozoic A-type granitic magmatism in the southwestern United States of America. Lithos 23, 19-52.], are the most problematic as they do not strictly follow the original definition of A-type granites, and approach calc-alkaline and I-type granites in some aspects. The oxidized Jamon suite A-type granites of the Carajás province of the Amazonian craton are compared with the magnetite-series granites of Laurentia, and other representative A-type granites, including Finnish rapakivi and Lachlan Fold Belt A-type granites, as well as with calc-alkaline, I-type orogenic granites. The geochemistry and petrogenesis of different groups of A-types granites are discussed with an emphasis on oxidized A-type granites in order to define their geochemical signatures and to clarify the processes involved in their petrogenesis. Oxidized A-type granites are clearly distinguished from calc-alkaline Cordilleran granites not only regarding trace element composition, as previously demonstrated, but also in their major element geochemistry. Oxidized A-type granites have high whole-rock FeO t/(FeO t + MgO), TiO 2/MgO, and K 2O/Na 2O and low Al 2O 3 and CaO compared to calc-alkaline granites. The contrast of Al 2O 3 contents in these two granite groups is remarkable. The CaO/(FeO t + MgO + TiO 2) vs. CaO + Al 2O 3 and CaO/(FeO t + MgO + TiO 2) vs. Al 2O 3 diagrams are proposed to distinguish A-type and calc-alkaline granites. Whole-rock FeO t/(FeO t + MgO) and the FeO t/(FeO t + MgO) vs. Al 2O 3 and FeO t/(FeO t + MgO) vs. Al 2O 3/(K 2O/Na 2O) diagrams are suggested for discrimination of oxidized and reduced A-type granites. Experimental data indicate that, besides pressure, the nature of A-type granites is dependent of ƒO 2 conditions and the water content of magma sources. Oxidized A-type magmas are considered to be derived from melts with appreciable water contents (? 4 wt.%), originating from lower crustal quartz-feldspathic igneous sources under oxidizing conditions, and which had clinopyroxene as an important residual phase. Reduced A-type granites may be derived from quartz-feldspathic igneous sources with a metasedimentary component or, alternatively, from differentiated tholeiitic sources. The imprint of the different magma sources is largely responsible for the geochemical and petrological contrasts between distinct A-type granite groups. Assuming conditions near the NNO buffer as a minimum for oxidized granites, magnetite-bearing granites formed near FMQ buffer conditions are not stricto sensu oxidized granites and a correspondence between oxidized and reduced A-type granites and, respectively, magnetite-series and ilmenite-series granites is not always observed.

Dall'Agnol, Roberto; de Oliveira, Davis Carvalho

2007-02-01

273

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

Microsoft Academic Search

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

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

2009-01-01

274

Geochemistry and origin of albite gneisses, northeastern Adirondack Mountains, New York  

Microsoft Academic Search

Albite gneisses containing up to 8.7 percent Na2O and as little as 0.1% K2O comprise a significant part of the Proterozoic Lyon Mountain Gneiss in the Ausable Forks Quadrangle of the northeastern Adirondacks, New York State. Two distinct types of albite gneisses are present. One is a trondhjemitic leucogneiss (LAG) consisting principally of albite (Ab95–Ab98) and quartz with minor magnetite

Philip R. Whitney; James F. Olmsted

1988-01-01

275

Geochemistry of Proterozoic Radioactive Arkoses in Khammam District, Andhra Pradesh, India: Evidence for K-rich Evolved Granitoid Upper Crust in the Late Archaean  

Microsoft Academic Search

Geochemical studies on radioactive arkoses (43–153 ppm U and 387–862 ppm Th) of the Proterozoic Pakhal Supergroup from Bangaruchilka, Khammam district, Andhra Pradesh, India, indicate that their gross major and trace element chemistry reflect their mineral composition. Chemically, arkoses are rich in silica (83% to 88% SiO2) and potassium (3% to 5% K2O), with consistently high Al2O3\\/Na2O (36 to 50)

Yamuna Singh

2001-01-01

276

Nanostructured bioglass thin films synthesized by pulsed laser deposition: CSLM, FTIR investigations and in vitro biotests  

Microsoft Academic Search

We report the synthesis by pulsed laser deposition of thin structures of two bioactive glasses belonging to the SiO2–Na2O–K2O–CaO–MgO–P2O5 system, on medical grade Ti substrates. We evaluated their biocompatibility after immersion in simulated body fluids and by performing cells adhesion tests. The films were characterized by confocal scanning laser microscopy and Fourier transform infrared spectrometry, before and after 30 and

L. Floroian; B. Savu; G. Stanciu; A. C. Popescu; F. Sima; I. N. Mihailescu; R. Mustata; L. E. Sima; S. M. Petrescu; D. Tanaskovic; Dj. Janackovic

2008-01-01

277

[Study on carving workers of Chong xiu zheng he jing shi zheng lei bei yong ben cao (Revised Prepared Materia Medica Classified under Syndromes in Zhenghe Period) published by Huiming Xuan (Huiming Sanctum)].  

PubMed

The ancient carving workers have made a great contribution to the xylographic printing art in ancient China, so the studies on them are significant for a survey of ancient Chinese printing history, and for the identification of ancient Chinese books edition. Zheng lei ben cao published by Huiming Xuan (Huiming Sanctum) in the Jin and Yuan dynasties, which is the earliest extant edition of Zhenghe version system of Zheng lei ben cao and has important literature value. Thirty carving workers were involved in its printing process. On the whole, these workers had a relatively high technique and completed a remarkably fine work. In addition to lettering, 28 persons of them also made a total of 536 pages with 900 exquisite engraving illustrations on Chinese materia medica included in this book. Because of the high levels on carving, this precious book has been the representative of Pingshui edition, which has a great reputation but has very few works now. PMID:23363847

Liang, Fei; Li, Jian; Zhang, Wei; Zhang, Rui-Xian

2012-11-01

278

Observation of Jonscher law in ac hopping conduction of the electron-doped nanoporous crystal 12CaO•7 Al2 O3 in a THz frequency range  

NASA Astrophysics Data System (ADS)

We have performed terahertz time-domain spectroscopy of carrier-doped nanoporous crystal 12CaO•7Al2O3 showing the Mott variable range hopping at room temperature. The real part of the dielectric constant clearly demonstrates the nature of localized carriers. The frequency dependence of both the real and imaginary parts of the dielectric constant can be simply explained by assuming two contributions: a dielectric response by the parent compound with no carriers and an ac hopping conduction with the Jonscher law generally reported up to GHz range. The possible obedience to the Jonscher law in the THz range suggests a relaxation time of the hopping carriers much faster than 1ps in the carrier-doped 12CaO•7Al2O3 .

Harimochi, H.; Kitagawa, J.; Ishizaka, M.; Kadoya, Y.; Yamanishi, M.; Matsuishi, S.; Hosono, H.

2004-11-01

279

ATALANTE 2004 Nmes (France) June 21-25, 2004 1 Structural Characterizations of Rare Earth-Rich Glasses for Nuclear Waste Immobilization  

E-print Network

.3 Al2O3 ­ 4.8 CaO ­ 3.2 ZrO2 ­ 16.0 Nd2O3. The aim of this study is to determine the local environmentO2 ­ 8.5 B2O3 ­ 12.2 Na2O ­ 4.3 Al2O3 ­ 4.8 CaO ­ 3.2 ZrO2 ­ 16.0 Nd2O3. In this simplified system

280

Structure and properties of solid solutions in the systems ZrO 2 -MgO, ZrO 2 CaO, and ZrO 2 -Y 2 O 3  

Microsoft Academic Search

Conclusions The phase formation and properties of solid solutions in the ZrO2-MgO, ZrO2-CaO, and ZrO2-Y2O3 systems have been studied over a wide range of concentrations and temperatures (1000–2000°C). The element of a phase diagram has been constructed for the ZrO2-MgO system in the subsolidus region.

A. G. Karaulov; E. I. Zoz; I. N. Rudyak; T. E. Sudarkina

1983-01-01

281

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

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

Barto?ová, Lucie; Klika, Zden?k

2014-07-01

282

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

E-print Network

properties of erbium ions. To our knowledge only few studies on nano-structured silica fibers were dedicatedRole of CaO addition in the local order around Erbium in SiO2­GeO2­P2O5 fiber preforms F. d in present technology. In this contribution we present a study on Er-doped fiber preforms where particular

Boyer, Edmond

283

Experimental constraints on the destabilization of basalt + calcite + anhydrite at high pressure-high temperature and implications for meteoroid impact modeling  

NASA Astrophysics Data System (ADS)

Calcite CaCO3 and anhydrite CaSO4 are two sedimentary components or alteration products of basalts on the Earth, Venus, and Mars. The fate of anhydrite-, calcite-bearing crust during a meteoroid impact must be addressed in order to evaluate: (1) the potential S- and C-gas release to the atmosphere, (2) the formation of S- and C-rich melts, and (3) the crystallization of S- and C-rich minerals which may be recognized by spectral analyses of planetary surfaces. We performed piston-cylinder experiments at 1 GPa, between 1200 and 1750 °C, on a mixture of 70 wt.% tholeiitic basalt + 15 wt.% anhydrite + 15 wt.% calcite. Up to ~ 1440 °C, an ultracalcic (CaO > 19.8 wt.%; CaO/Al2O3 > 1 wt.%) picrobasaltic (SiO2 ~ 39-43 wt.%; Na2O + K2O < 2 wt.%) melt containing up to 5.7 wt.% SO3 and up to 5.1 wt.% CO2 + H2O (calculated by difference) is present in equilibrium with fassaitic clinopyroxene, anhydrite, scapolite, chromian spinel and a gas composed mainly of CO and, occasionally, aliphatic thiols like CH3(CH2)3SH. Hydrogen was incorporated either by contact between the starting material and air or by diffusion through the capsule during the experiments. Above ~ 1440 °C, a CaO-rich (~ 35 wt.%) sulfate-carbonate (SC) melt which contains 41-47 wt.% SO3, 7-12 wt.% CO2 + H2O and a few percent of Na2O, forms in equilibrium with the picrobasaltic melt. This study shows that a meteoroid impact onto an anhydrite- and calcite-bearing basaltic crust is likely to release CO gas to the atmosphere, while S is trapped in solid or liquid phases. Under hydrous conditions, however, the S/C in the gas may increase. The importance of the temperature parameter on the impact phase relations is also demonstrated. In particular, SC melt may form by meteoroid impact, and flow rapidly on a planetary surface. Physical modeling must therefore be combined with high P-high T phase diagrams of complex assemblages similar to planetary lithologies in order to evaluate the effects of a meteoroid impact.

Martin, A. M.; Righter, K.; Treiman, A. H.

2012-05-01

284

A study of crystals and glasses from the 2011 submarine eruption at El Hierro, Canary Islands  

NASA Astrophysics Data System (ADS)

A submarine eruption began off the south coast of El Hierro, Canary Islands, on 10 October 2011. This is the first confirmed eruption at El Hierro in over 500 years of historical records. Here we present preliminary results on the composition of crystals, matrix glass and glass (melt) inclusions from samples erupted on ca. 15 October and on 1 November 2011. While the October samples are glassy, aphyric lava crusts enveloping xenoliths of sedimentary origin (see Troll et al., 2011), the November sample is a fragment of a block composed entirely of juvenile lava bearing crystals of olivine (Fo79-81), Fe-Ti oxides and clinopyroxene (Mg#=71-79). Microprobe analyses of microlite-poor matrix glass chips from the October and November samples are similiar and yield an average basanite composition of 45.2 wt.% SiO2, 4.3 wt.% TiO2, 4.8 wt.% MgO and 6.4 wt.% alkalis (Na2O + K2O). A few highly vesicular, microlite-rich glass shards from the 1 November sample have slightly lower MgO and CaO, and higher FeO(t) and Na2O, attesting to the effect of rapid microlite crystallisation on glass composition. Chlorine and sulphur concentrations in matrix glass range from 710-1270 ppm and 300-640 ppm, respectively. The uncorrected compositions of melt inclusions largely overlap with the matrix glass major element and chlorine data. By contrast, melt inclusions show much higher sulphur concentrations, with a range of 660-3950 ppm. Indeed, 60% of analysed melt inclusions (n=38) yield S concentrations above 1500 ppm. Such high S concentrations are uncommon for MORB and OIB, with a few examples from Loihi Seamount (up to 3330 ppm; Hauri, 2002), and Gran Canaria (up to 5810 ppm; Gurenko and Schmincke, 2000), and have important implications for the mantle source and degassing of Canary Island volcanoes. In addition, preliminary results on clinopyroxene-melt barometry yield crystallisation pressures corresponding to uppermost mantle depths beneath El Hierro, in remarkable agreement with syn-eruptive seismicity.

Longpré, M. A.; Klügel, A.; Stix, J.; Hansteen, T. H.; Troll, V. R.

2012-04-01

285

Inorganic geochemistry data from Lake El'gygytgyn sediments: marine isotope stages 6-11  

NASA Astrophysics Data System (ADS)

Geochemical analyses were performed on sediments recovered by deep drilling at Lake El'gygytgyn in central Chukotka, northeastern Russia (67°30' N; 172°05' E). Major and rare element concentrations were determined using X-ray fluorescence spectroscopy (XRF) on the < 250 ?m fraction from 617 samples dated to ca. 440 and 125 ka, which approximates marine isotope stages (MIS) 11 to 6. The inorganic geochemistry indicates significant variations in elemental composition between glaciations and interglaciations. Interglacial sediments are characterized by high contents of SiO2, Na2O, CaO, K2O, and Sr and are depleted in Al2O3, Fe2O3, TiO2, and MgO. An extreme SiO2 enrichment during MIS 11.3 and 9.3 was caused by an enhanced flux of biogenic silica (BSi). The geochemical structure of MIS 11 shows similar characteristics as seen in MIS 11 records from Lake Baikal (southeastern Siberia) and Antarctic ice cores, thereby arguing for the influence of global forcings on these records. High sediment content of TiO2, Fe2O3, MgO, Al2O3, LOI, Ni, Cr, and Zr typifies glacial stages, with the most marked increases during MIS 7.4 and 6.6. Reducing conditions during glacial times are indicated by peaks in the Fe2O3 content and coinciding low Fe2O3/MnO ratios. This conclusion also is supported by P2O5 and MnO enrichment, indicating an increased abundance of authigenic, fine-grained vivianite. Elemental ratios (CIA, CIW, PIA, and Rb/Sr) indicate that glacial sediments are depleted in mobile elements, like Na, Ca, K and Sr. This depletion was caused by changes in the sedimentation regime and thus reflects environmental changes.

Minyuk, P. S.; Borkhodoev, V. Y.; Wennrich, V.

2014-03-01

286

Geochemistry of the Paleocene-Eocene and Miocene-Pliocene clayey materials of the eastern part of the Wouri River (Douala sub-basin, Cameroon): Influence of parent rocks  

NASA Astrophysics Data System (ADS)

Major and trace element concentrations of clay deposits of the Missole II and Bomkoul respectively from the Paleocene-Eocene N'Kapa Formation and the Miocene-Pliocene-Matanda-Wouri Formation in the eastern part of the Wouri River in the Douala sub-basin of Cameroon have been investigated to identify the parent rocks. To carry out this study, X-ray diffraction, inductively coupled plasma-atomic emission spectrometry (ICP/AES) and inductively coupled plasma-mass spectrometry (ICP/MS) were performed to determine respectively the mineralogical and chemical data of Missole II and Bomkoul clayey materials. Clay sediments are essentially kaolinitic and illitic, and kaolinitic and smectitic respectively in both sites. They are generally siliceous, aluminous with small iron and bases (MgO, CaO, Na2O, and K2O) contents. Samples of Missole II profiles are more siliceous than those from the Bomkoul grey and dark grey clayey materials. Clayey materials have high Chemical Index of Alteration (CIA = 80-99.34) which suggests that they are strongly weathered under humid tropical climate before and after their deposition in the coastal plain. The value of Eu/Eu* (0.48-0.61), La/Sc (2.15-20.50), Th/Sc (0.74-2.25), Th/Co (1.08-8.33), and Cr/Th (5.24-13.55) ratios support essentially a silicic or felsic parent rocks. Total REE concentrations reflect the variations in their grain-size fractions. Chondrite-normalised REE patterns with LREE enrichment, flat HREE, and negative Eu anomaly are attributed essentially to silicic or felsic parent rocks like those from weathered materials developed from the gneisses around the coastal plain in the littoral part of Cameroon (Noa Tang et al., 2012), main characteristic of Paleocene-Eocene and Miocene-Pliocene clay sediments of Missole II and Bomkoul areas.

Ngon Ngon, G. F.; Mbog, M. B.; Etame, J.; Ntamak-Nida, M. J.; Logmo, E. O.; Gerard, M.; Yongue-Fouateu, R.; Bilong, P.

2014-03-01

287

Inorganic data from El'gygytgyn Lake sediments: stages 6-11  

NASA Astrophysics Data System (ADS)

Geochemical study was performed on sediment of deep drilling core from El'gygytgyn Lake, located in central Chukotka, northeastern Russia (67°30' N; 172°05' E). Major and rare elements were determined by X-ray fluorescence spectroscopy (XRF) on 600 samples covering the timeframe between ca. 450 and 125 ka corresponding to Marine Isotope Stages (MIS) 11 to 6. Inorganic geochemistry data indicates significant variations in the elemental compositions corresponding to the glacials and interglacials periods. Interglacial sediments are characterized by high contents of SiO2, Na2O, CaO, K2O, Sr and are depleted in Al2O3, Fe2O3, TiO2, MgO. Extreme enrichments in SiO2 during MIS 11.3 and 9.3 are caused by an enhanced flux of biogenic silica (BSi). Geochemical structure of stage 11 shows very similar peculiarities to features of stage 11 from records of Lake Baikal/SE Siberia and Antarctic ice cores. High contents of TiO2, Fe2O3, MgO, Al2O3, LOI, Ni, Cr and Zr are typical for sediments of glacial stages, among those MIS 7.4 and 6.6 are the most marked. Peaks in the Fe2O3 content and coinciding low Fe2O3/MnO ratios during glacials indicate reducing condition in the sediments. This is also supported by enrichments in P2O5 and MnO, indicating an increased abundance of authigenic fine grained vivianite. Some elemental ratios indicate an enhanced alteration of glacial sediments accompanied by a loss of mobile elements, like Na, Ca, K and Sr. The higher alteration of sediments can presumably be traced back to changes in the sedimentation regime and diagenetic processes, and thus, reflects environmental changes.

Minyuk, P. S.; Borkhodoev, V. Ya.; Wennrich, V.

2013-01-01

288

Comparing results from two continental geochemical surveys to world soil composition and deriving Predicted Empirical Global Soil (PEGS2) reference values  

NASA Astrophysics Data System (ADS)

Analytical data for 10 major oxides (Al2O3, CaO, Fe2O3, K2O, MgO, MnO, Na2O, P2O5, SiO2 and TiO2), 16 total trace elements (As, Ba, Ce, Co, Cr, Ga, Nb, Ni, Pb, Rb, Sr, Th, V, Y, Zn and Zr), 14 aqua regia extracted elements (Ag, As, Bi, Cd, Ce, Co, Cs, Cu, Fe, La, Li, Mn, Mo and Pb), Loss On Ignition (LOI) and pH from 3526 soil samples from two continents (Australia and Europe) are presented and compared to (1) the composition of the upper continental crust, (2) published world soil average values, and (3) data from other continental-scale soil surveys. It can be demonstrated that average upper continental crust values do not provide reliable estimates for natural concentrations of elements in soils. For many elements there exist substantial differences between published world soil averages and the median concentrations observed on two continents. Direct comparison with other continental datasets is hampered by the fact that often mean, instead of the statistically more robust median, is reported. Using a database of the worldwide distribution of lithological units, it can be demonstrated that lithology is a poor predictor of soil chemistry. Climate-related processes such as glaciation and weathering are strong modifiers of the geochemical signature inherited from bedrock during pedogenesis. To overcome existing shortcomings of predicted global or world soil geochemical reference values, we propose Preliminary Empirical Global Soil reference values based on analytical results of a representative number of soil samples from two continents (PEGS2).

de Caritat, Patrice; Reimann, Clemens; Bastrakov, E.; Bowbridge, D.; Boyle, P.; Briggs, S.; Brown, D.; Brown, M.; Brownlie, K.; Burrows, P.; Burton, G.; Byass, J.; de Caritat, P.; Chanthapanya, N.; Cooper, M.; Cranfield, L.; Curtis, S.; Denaro, T.; Dhnaram, C.; Dhu, T.; Diprose, G.; Fabris, A.; Fairclough, M.; Fanning, S.; Fidler, R.; Fitzell, M.; Flitcroft, P.; Fricke, C.; Fulton, D.; Furlonger, J.; Gordon, G.; Green, A.; Green, G.; Greenfield, J.; Harley, J.; Heawood, S.; Hegvold, T.; Henderson, K.; House, E.; Husain, Z.; Krsteska, B.; Lam, J.; Langford, R.; Lavigne, T.; Linehan, B.; Livingstone, M.; Lukss, A.; Maier, R.; Makuei, A.; McCabe, L.; McDonald, P.; McIlroy, D.; McIntyre, D.; Morris, P.; O'Connell, G.; Pappas, B.; Parsons, J.; Petrick, C.; Poignand, B.; Roberts, R.; Ryle, J.; Seymon, A.; Sherry, K.; Skinner, J.; Smith, M.; Strickland, C.; Sutton, S.; Swindell, R.; Tait, H.; Tang, J.; Thomson, A.; Thun, C.; Uppill, B.; Wall, K.; Watkins, J.; Watson, T.; Webber, L.; Whiting, A.; Wilford, J.; Wilson, T.; Wygralak, A.; Albanese, S.; Andersson, M.; Arnoldussen, A.; Baritz, R.; Batista, M. J.; Bel-lan, A.; Birke, M.; Cicchella, C.; Demetriades, A.; Dinelli, E.; De Vivo, B.; De Vos, W.; Duris, M.; Dusza-Dobek, A.; Eggen, O. A.; Eklund, M.; Ernstsen, V.; Filzmoser, P.; Finne, T. E.; Flight, D.; Forrester, S.; Fuchs, M.; Fugedi, U.; Gilucis, A.; Gosar, M.; Gregorauskiene, V.; Gulan, A.; Halami?, J.; Haslinger, E.; Hayoz, P.; Hobiger, G.; Hoffmann, R.; Hoogewerff, J.; Hrvatovic, H.; Husnjak, S.; Janik, L.; Johnson, C. C.; Jordan, G.; Kirby, J.; Kivisilla, J.; Klos, V.; Krone, F.; Kwecko, P.; Kuti, L.; Ladenberger, A.; Lima, A.; Locutura, J.; Lucivjansky, P.; Mackovych, D.; Malyuk, B. I.; Maquil, R.; McLaughlin, M.; Meuli, R. G.; Miosic, N.; Mol, G.; Négrel, P.; O'Connor, P.; Oorts, K.; Ottesen, R. T.; Pasieczna, A.; Petersell, V.; Pfleiderer, S.; Po?avi?, M.; Prazeres, C.; Rauch, U.; Reimann, C.; Salpeteur, I.; Schedl, A.; Scheib, A.; Schoeters, I.; Sefcik, P.; Sellersjö, E.; Skopljak, F.; Slaninka, I.; Šorša, A.; Srvkota, R.; Stafilov, T.; Tarvainen, T.; Trendavilov, V.; Valera, P.; Verougstraete, V.; Vidojevi?, D.; Zissimos, A. M.; Zomeni, Z.

2012-02-01

289

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

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

290

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

SciTech Connect

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.

Fluegel, Alex

2010-10-01

291

Alteration of plagioclase to nepheline in the Khariar alkaline complex, SE India: Constraints on metasomatic replacement reaction mechanisms  

NASA Astrophysics Data System (ADS)

At the Khariar alkaline complex in southeastern India, some tholeiitic amphibolites inter-layered with syenite and nepheline syenite show microtextural evidence of fenitization. Typical metasomatic textures include the replacement of plagioclase by vein nepheline and albitic-plagioclase or by symplectitic nepheline + albite + Na-Al-rich clinopyroxene. Whole rock mass balance calculations indicate that the fenitized variants gained alkalis (Na + K), some large ion lithophile elements (Sr, Rb and Ba) and high field strength elements like Zr and Hf during the metasomatic exchange. The plagioclase replacement textures can be explained by a fluid-mediated coupled dissolution-reprecipitation process whereby the infiltration of alkali-bearing fluid along grain boundaries and deformation-induced intragranular fractures led to the dissolution of the host plagioclase along an inward moving reaction interface. Na+ ions were introduced and Ca2 + ions removed by the fluid phase. The Al and Si released from the breakdown of the anorthite component of the plagioclase combined with Na+ from the fluid to precipitate nepheline + albitic-plagioclase or Na-Al-rich clinopyroxene. Reaction enhanced cracking during metasomatism due to local volume changes in the alteration zone produced a hierarchical system of fractures. Mass-balance calculations using the volume proportion of phases in the plagioclase replacement zones show that SiO2 and Al2O3 were broadly conserved during the replacement; there was significant loss of CaO (ca. 73%) and huge gains of Na2O and K2O. These results indicate that alkali and alkaline elements (Na, K and Ca) were exchanged freely between the fluid phase and the reaction zone whereas Si and Al released during plagioclase dissolution were consumed in the replacement zone itself to form nepheline and albite-rich plagioclase or Na-Al-rich clinopyroxene. The trace element and Sr-Nd isotope signature of the rocks indicate that the fenitizing fluids were derived from the nepheline syenites.

Upadhyay, Dewashish

2012-12-01

292

Classification and statistical analysis of mine spoils chemical composition from Oliete basin (Teruel, NE Spain)  

NASA Astrophysics Data System (ADS)

The Oliete basin (Early Cretaceous, NE Teruel, Spain) is one of the most important areas for the supply of mine spoils used as ball clays for the production of white and red stoneware in the Spanish ceramic industry of wall and floor tiles. This study corresponds to the second part of the paper published recently by Meseguer et al. (Environ Geol 2008) about the use of mine spoils from Teruel coal mining district. The present study shows a statistical data analysis from chemical data (major, minor and trace elements). The performed statistical analysis of chemical data included descriptive statistics and cluster analysis (with ANOVA and Scheffé methods). The cluster analysis of chemical data provided three main groups: C3 with the highest mean SiO2 content (66%) and lowest mean Al2O3 content (20%); C2 with lower SiO2 content (48%) and higher mean Al2O3 content (28%); and C1 with medium values for the SiO2 and Al2O3 mean content. The main applications of these materials are refractory, white and red ceramics, stoneware, heavy ceramics (including red earthenware, bricks and roof tiles), and components of white Portland cement and aluminous cement. Clays from group 2 are used in refractories (with higher kaolinite content, and constrictions to CaO + MgO and K2O + Na2O contents). All materials can be used in fine ceramics (white or red, according to the Fe2O3 + TiO2 content).

Meseguer, S.; Sanfeliu, T.; Jordán, M. M.

2009-02-01

293

Petrography and geochemistry of lower carboniferous greywacke and mudstones in Northeast Junggar, China: Implications for provenance, source weathering, and tectonic setting  

NASA Astrophysics Data System (ADS)

Northeast Junggar occupies an important position that links East Junggar and Chinese Altai. Numerous magmatic and sedimentary rocks of the Paleozoic in this area recorded the final amalgamation processes of East Junggar and Chinese Altai. This study analyzes the petrological and geochemical characteristics of sandstones and mudstones from the Early Carboniferous Nanmingshui formation in Northeast Junggar. The provenance and tectonic setting of these clastic rocks are discussed. Petrography indicates that the composition and texture maturity of the sandstones are low. The components of the sandstones are mainly volcanic fragments (61-87%), feldspars (9-30%), and monocrystalline quartz (2-18%), with a few polycrystalline quartz and other minerals. Slice observation indicates that the majority of the volcanic fragments of sandstones are basic-intermediate volcanic rocks with a few dacite and felsic plutonic fragments. The detrital modes of the sandstones reflect that these sandstones are derived from undissected arcs. A low to moderate chemical index of alteration and the Al2O3-CaO* + Na2O-K2O diagram reflect a low to moderate weathering degree in the source area. Trace and rare earth element (e.g., La, Th, Hf, Sc, Cr, Co, and Eu) contents and their ratios suggest that the source rocks of the clastic rocks are intermediate-basic rocks with some felsic rocks. Compared with sandstones, the source rocks for mudstones are more felsic. The petrography and geochemistry characteristics of the clastic rocks suggest that the proximal Dulate arc should be the primary source area. Mixing calculations based on REE data suggest that approximately two-thirds of the sandstone fragments are intermediate-basic volcanic rocks. The contents of the major and trace elements, as well as the stratum features, of the clastic rocks manifest that these clastic rocks resemble sedimentary rocks in a back-arc basin. The formation of this back-arc basin is caused by the southward subduction of the Zaysan-Erqis Ocean.

Tao, Huifei; Sun, Shu; Wang, Qingchen; Yang, Xiaofa; Jiang, Lin

2014-06-01

294

[Rapid determination of major and trace elements in the salt lake clay minerals by X-ray fluorescence spectrometry].  

PubMed

A rapid multi-element analysis method for clay mineral samples was described. This method utilized a polarized wave-length dispersive X-ray fluorescence spectrometer--Axios PW4400, which had a maximum tube power of 4 000 watts. The method was developed for the determination of As, Mn, Co, Cu, Cr, Dy, Ga, Mo, P, Pb, Rb, S, Sr, Ni, ,Cs, Ta, Th, Ti, U, V, Y, Zn, Zr, MgO, K2O, Na2O, CaO, Fe2O3, Al2O3, SiO2 and so on. Thirty elements in clay mineral species were measured by X-ray fluorescence spectrometry with pressed powder pellets. Spectral interferences, in particular the indirect interferences of each element, were studied. A method to distinguish the interference between each other periodic elements in element periodic table was put forward. The measuring conditions and existence were mainly investigated, and the selected background position as well as corrected spectral overlap for the trace elements were also discussed. It was found that the indirect spectral overlap line was the same important as direct spectral overlap line. Due to inducing the effect of indirect spectral overlap, some elements jlike Bi, Sn, W which do not need analysis were also added to the elements channel. The relative standard deviation (RSD) was in the range of 0.01% to 5.45% except three elements Mo, Cs and Ta. The detection limits, precisions and accuracies for most elements using this method can meet the requirements of sample analysis in clay mineral species. PMID:20496720

Wang, Xiao-Huan; Meng, Qing-Fen; Dong, Ya-Ping; Chen, Mei-Da; Li, Wu

2010-03-01

295

Effect of float glass composition on liquidus temperature and devitrification behaviour  

SciTech Connect

Liquidus temperatures (TL) were measured for the following float glass-type composition region (in mass%): 72?7 to 74?0 SiO2, 13?1 to 14?2 Na2O, 7?95 to 8?95 CaO, 2?97 to 3?97 MgO, 0?10 to 0?45 Al2O3, and 0?03 to 0?10 K2O. Glasses also contained constant minor fractions of Fe2O3 (0?71) and TiO2 (0?01). Fractions of silica, wollastonite, and devitrite were determined in glasses quenched from 900 C. Partial specific values for TL were evaluated for silica and wollastonite phase-fields. The measured TL values were compared with values estimated using various models available in the literature. The differences between predicted and measured TL for the float glass composition region can be attributed to several causes, the most prominent being the neglecting of differences in the slopes of liquidus surfaces within different primary phase-fields. Inaccurate estimates can also be expected when a model is applied to a glass with a smaller or a larger number of key components. Finally, erroneous estimates occur when the model is extrapolated beyond the composition region covered by data to which model equations were fitted, or when a model that covers a large composition region is applied to a smaller subregion where the TL -composition relationship has a significant lack of fit.

Hrma, Pavel R.; Smith, D. E.; Matyas, Josef; Yeager, John D.; Jones, James V.; Boulos, Edward N.

2006-06-01

296

Melt inclusions in quartz from an evolved peraluminous pegmatite: Geochemical evidence for strong tin enrichment in fluorine-rich and phosphorus-rich residual liquids  

NASA Astrophysics Data System (ADS)

We have investigated the magmatic evolution of a late-stage, F- and P-rich, pegmatite-forming aluminosilicate liquid and the geochemical controls on magmatic mineralizing processes by remelting totally-crystallized melt inclusions in quartz and analyzing the quenched glass by EPMA and SIMS. The quartz phenocrysts were sampled from a pegmatite that occurs in a Variscan granite genetically associated with cassiterite- and wolframite-mineralized greisen veins at the Ehrenfriedersdorf Sn?W deposit, central Erzgebirge, SE Germany. The melt inclusion compositions imply that the pegmatite-forming liquid achieved extreme levels of chemical differentiation. It contained high abundances of Sn, F, P, Li, Rb, Cs, Nb, Ta, and Be and abnormally low concentrations of Ca, Y, Sr, and REE for a granite, and it was strongly peraluminous (the molar [Al 2O 3/CaO + Na 2O + K 2O] ranged from 1.3 to 2.0). Fractions of the pegmatite-forming liquid were extremely enriched in P 2O 5 + F + Al 2O 3, and the molar abundances of (F + P) in the glasses correlate strongly with moles of network-modifying Al ions implying that the bulk liquid included F-, P-, and Al-bearing complexes. Formation of these complexes reduced the activities of F, P, and Al in bulk liquid, suppressed the crystallization of magmatic topaz and P-rich minerals, and allowed the liquid to become enriched in these constituents. Some fractions of the Ehrenfriedersdorf aluminosilicate liquid contained 1000-2000 ppm Sn. These levels of Sn enrichment were up to 2 orders of magnitude greater than that ever reported for nonmineralized, metaluminous and peraluminous igneous materials and are consistent with some experimentally-derived Sn solubilities in cassiterite-saturated granitic liquids at geologically relevant pressures and temperatures. This concordance implies that cassiterite could have crystallized directly from this highly evolved, P- and F-rich peraluminous granitic liquid without the involvement of hydrothermal fluids.

Webster, James D.; Thomas, Rainer; Rhede, Dieter; Förster, Hans-Jürgen; Seltmann, Reimar

1997-07-01

297

Mineralogical, geochemical and radiological characterisation of Selmo Formation in Batman area, Turkey.  

PubMed

This work deals with the mineralogical, geochemical and radiological characterisations of Selmo Formation in Batman neighbourhood. The upper Miocene-Pliocene Selmo Formation is common in the centre of Batman and composed of carbonated sandy claystones and silty-sandy stone lenses. The common whole minerals of the samples are quartz, feldspars, calcite and dolomite. The clay minerals are smectite, illite, chlorite and mixed-layer clay (chlorite-smectite). The geochemical mean values of the samples are 51.7% SiO(2); 12.6% Al(2)O(3); 6.2% Fe(2)O(3); 3.6% MgO; 6.3% CaO; 1.1% Na(2)O; 1.7% K(2)O; 0.8% TiO(2); 0.2% P(2)O(5); 0.1% MnO; and 0.03% Cr(2)O(3). In addition, baseline maps for the concentrations of each radionuclide, the radium equivalent activity and the outdoor gamma dose rate distributions have been plotted for the study area. The mean activity concentrations of (226)Ra, (232)Th, (40)K and (137)Cs were determined to be 32, 24, 210 and 9 Bq kg(-1), respectively. The assessments of the radiological hazard indices, such as radium equivalent activity, absorbed dose rate in air, annual effective dose equivalent, excess lifetime cancer risk, external hazard index and internal hazard index, were calculated and compared with the internationally accepted reference values. This study shows that the concentrations of radioactivities in the measured samples were within the recommended safety limits and did not pose to be any significant source of radiation hazard. PMID:22316137

Isik, Umit; Damla, Nevzat; Akkoca, Dicle Bal; Cevik, U?ur

2012-06-01

298

In situ calibration using univariate analyses based on the onboard ChemCam targets: first prediction of Martian rock and soil compositions  

NASA Astrophysics Data System (ADS)

Curiosity rover landed on August 6th, 2012 in Gale Crater, Mars and it possesses unique analytical capabilities to investigate the chemistry and mineralogy of the Martian soil. In particular, the LIBS technique is being used for the first time on another planet with the ChemCam instrument, and more than 75,000 spectra have been returned in the first year on Mars. Curiosity carries body-mounted calibration targets specially designed for the ChemCam instrument, some of which are homgeneous glasses and others that are fine-grained glass-ceramics. We present direct calibrations, using these onboard standards to infer elements and element ratios by ratioing relative peak areas. As the laser spot size is around 300 ?m, the LIBS technique provides measurements of the silicate glass compositions representing homogeneous material and measurements of the ceramic targets that are comparable to fine-grained rock or soil. The laser energy and the auto-focus are controlled for all sequences used for calibration. The univariate calibration curves present relatively to very good correlation coefficients with low RSDs for major and ratio calibrations. Trace element calibration curves (Li, Sr, and Mn), down to several ppm, can be used as a rapid tool to draw attention to remarkable rocks and soils along the traverse. First comparisons to alpha-particle X-ray spectroscopy (APXS) data, on selected targets, show good agreement for most elements and for Mg# and Al/Si estimates. SiO2 estimates using univariate cannot be yet used. Na2O and K2O estimates are relevant for high alkali contents, but probably under estimated due to the CCCT initial compositions. Very good results for CaO and Al2O3 estimates and satisfactory results for FeO are obtained.

Fabre, C.; Cousin, A.; Wiens, R. C.; Ollila, A.; Gasnault, O.; Maurice, S.; Sautter, V.; Forni, O.; Lasue, J.; Tokar, R.; Vaniman, D.; Melikechi, N.

2014-09-01

299

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

DOE PAGESBeta

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 in 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.

Vienna, John D. [Pacific Northwest National Laboratory; Kim, Dong-Sang [Pacific Northwest National Laboratory; Muller, I. S. [The Catholic University National Laboratory; Kruger, Albert A. [Department of Energy -- Ofice of River Protection; Piepel, Gregory F. [Pacific Northwest National Laboratory

2014-10-01

300

Application of chemical, physical and chemometric analytical techniques to the study of ancient ceramic oil lamps.  

PubMed

A chemical, mineralogical and morphological characterization of 54 fragments of oil lamps found in two Spanish archaeological sites (Cordoba and Herrera de Pisuerga (Palencia)) has been performed. Flame atomic absorption and emission spectrometry were used for the determination of Al(2)O(3), CaO, Fe(2)O(3), K(2)O, MgO, MnO, Na(2)O and TiO(2) as major constituents and Cu, Cr, Ni, Pb and Zn as minor and trace selected elements. Physical, mineralogical and morphological analyses were made by using dilatometry at constant heating rate for the thermal behaviour, X-ray diffraction spectrometry for the mineralogical composition and, in a group of selected samples, scanning electron microscopy and polarizing petrographic microscopy for the observation of thin layers and mineral identification. Separations of light and heavy minerals were carried out with bromoform and X-ray diffraction analysis was applied to both fractions. Multivariate statistical analysis was used to establish correlations between variables and to deduce factors which allow the gathering of oil lamp samples in groups as a function of their composition. The results of these analyses allow the comparison among pieces and the establishment of conclusions about several aspects of their manufacture, the origin of the raw materials and the provenance of the oil lamps (local or imported). They provide information supporting certain archaeological hypothesis. For example, some oil lamps found in Herrera de Pisuerga showed a clearly different physicochemical composition. They were probably brought from Italy by the Roman Legions together with their initial furniture household. PMID:18970455

García Giménez, R; Vigil de la Villa, R; Petit Domínguez, M D; Rucandio, M I

2006-02-15

301

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

302

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

303

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

USGS Publications Warehouse

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.

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

1981-01-01

304

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

USGS Publications Warehouse

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.

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

2002-01-01

305

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

PubMed

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

Nery, José Reinaldo Cardoso; Bonotto, Daniel Marcos

2011-04-01

306

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

PubMed

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

Nakayama, Kenichi; Nakamura, Toshihiro

2005-07-01

307

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

SciTech Connect

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.

Motzer, W.E.

1996-01-01

308

Deciphering heavy metal contamination zones in soils of a granitic terrain of southern India using factor analysis and GIS  

NASA Astrophysics Data System (ADS)

Soil contamination by heavy metals has been a major concern for last few decades due to increase in urbanization and industrialization. The main objective of this research was to identify the heavy metal contaminated zones in the study area. Twenty five soil samples collected throughout the agriculture, residential and industrial areas were analysed by X-ray Fluorescence Spectrometer (XRF) for trace metals and major oxides. These metals can affect the quality of soil and infiltrate through the soil, thereby causing groundwater pollution. Based on the chemical analysis of major oxides (SiO2, Al2O3, Fe2O3, MnO, MgO, CaO, Na2O, K2O, TiO2, and P2O5) and their distribution; it is observed that these soils are predominantly siliceous type with slight enrichment of alumina component in the study area. Correlation matrix (CM) and factor analysis (FA) is employed to the heavy metal variables, viz., Ba, Cr, Cu, Ni, Pb, Rb, Sr, V, Y, Zn and Zr of the soil to determine the dominant factors contributing to the soil contamination in the area. In the analysis, five factors emerged as significant contributors to the soil quality. The total contribution of these five factors is about 90%. The contribution of the first factor is about 45% and has significant positive loadings of Co, Cr, Cu, Ni and Zn. The contribution of second factor is 22% and has significant positive loadings of Rb, Sr and Y. The contribution of third, fourth and fifth factors is 10, 8 and 5% and show positive loadings for lead, molybdenum and barium respectively to the soil contamination. The spatial variation maps deciphering different zones of heavy metal concentration in the soil were generated in a GIS (geographic information system) based environment using ArcGIS 9.3.1. The results reveal that heavy metal contamination in the area is mainly due to anthropogenic activities.

Purushotham, D.; Lone, Mahjoor Ahmad; Rashid, Mehnaz; Rao, A. Narsing; Ahmed, Shakeel

2012-08-01

309

Preparation, structure and bioactivity of xAu 2O 3·(100 - x)[P 2O 5·CaO] glass system  

NASA Astrophysics Data System (ADS)

Gold doped calcium phosphate glasses were prepared by the melting method. The structure of Au 2O 3-P 2O 5-CaO glasses is investigated using X-ray diffraction, infrared absorption and Raman scattering. The depth characterization of their structures is essential for the understanding of the properties of biocompatible materials. Thermal analysis DTA and TGA were also made to study behavior under different temperature regions and to see chemical changes versus time and temperature of these glasses. Bioactivity of the glasses was investigated in vitro by examining apatite formation on the surface of glasses treated in acellular simulated body fluid (SBF) with ion concentrations nearly equal to those in human blood plasma. Formation of bioactive apatite layer on the samples treated in SBF for 28 days at 37 °C was confirmed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The effect of SBF soaking induces structural changes on the surface, reflected by the appearance of nano-crystalline particles agglomerated into micro-aggregates.

Regos, Adriana N.; Ardelean, I.

2011-12-01

310

Single-crystal EPR of the Eu2+ ion in pentacalcium-oxide trialuminate, 5CaO·3Al2O3  

NASA Astrophysics Data System (ADS)

X-band (?9.8 GHz) EPR studies on a single crystal of pentacalcium-oxide trialuminate (5CaO·3Al2O3) doped with Eu2+ were carried out at 4.2, 77.4 K and in the range 120-300 K. The site symmetry, as revealed by the angular variation of the EPR spectrum, was found to be nearly axial. The Eu2+ spin-Hamiltonian parameters were estimated from the positions of the EPR lines at various temperatures. The absolute sign of the zero-field splitting parameter, B20, was determined to be positive from the relative intensities of lines at liquid-helium temperature. The resolved Eu2+ hyperfine (HF) structure was observed only for a few fine-structure EPR lines, and only at some orientations of the external magnetic field. HF-interaction constants for the 151Eu and 153Eu isotopes were estimated from an analysis of the partly resolved HF structure.

Misra, S. K.; Andronenko, S. I.

2000-12-01

311

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

SciTech Connect

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 temperature of the secondary bed (780--910 C), time of contact or space-time of the gas (0.08--0.32 kg{center_dot}h/m{sup 3}n), and particle diameter (1--4 mm) and type of mineral. Their effects on tar conversion, tar amount in the exit gas, product distribution, and gas composition are presented. Using a macrokinetic model for the tar disappearance network, the activities of the stones are expressed by their apparent kinetic constant. Apparent energies of activation for tar elimination (42--47 kJ/mol) and preexponential and effectiveness factors are given for all tested solids of which the most active is the calcined dolomite.

Delgado, J.; Aznar, M.P. [Univ. of Saragossa (Spain). Dept. of Chemical and Environmental Engineering] [Univ. of Saragossa (Spain). Dept. of Chemical and Environmental Engineering; Corella, J. [Univ. Complutense of Madrid (Spain). Dept. of Chemical Engineering] [Univ. Complutense of Madrid (Spain). Dept. of Chemical Engineering

1997-05-01

312

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

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

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

2013-10-01

313

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)

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.

Bovi, Daniele; Narzi, Daniele; Guidoni, Leonardo

2014-01-01

314

Nanoporous crystal 12CaO.7Al2O3: a playground for studies of ultraviolet optical absorption of negative ions.  

PubMed

A novel nanoporous material 12CaO.7Al2O3 (C12A7) offers a possibility of incorporating large concentrations (>1021 cm-3) of a wide range of extraframework anions inside its nanopores. We have investigated, both experimentally and theoretically, optical absorption associated with several types of such anions, including F-, OH-, O-, O2-, O2-, and O22-, and assigned their optical absorption bands. It is demonstrated that the chemical identity and concentration of extraframework anions can be controlled by an appropriate treatment of "as grown" C12A7. We also show that the position of the adsorption edge is, in turn, determined by the chemical identity of the extraframework species and can be varied in the range of approximately 4-6 eV. We suggest that C12A7 is a unique host material, which can be used as a playground for studying negatively charged species that are unstable in other environments. PMID:17269815

Hayashi, Katsuro; Sushko, Peter V; Ramo, David Muñoz; Shluger, Alexander L; Watauchi, Satoshi; Tanaka, Isao; Matsuishi, Satoru; Hirano, Masahiro; Hosono, Hideo

2007-03-01

315

Luminescence and energy transfer characteristics of Ce3+- and Tb3+-codoped nanoporous 12CaO 7Al2O3 phosphors.  

PubMed

The novel green-emitting phosphors of 12CaO 7Al2O3:Ce3+ , Tb3+ (C12A7:Ce3+, Tb3+) were synthesized by a solid-state reaction. Upon the excitation of Ce3+ at 350 nm, the C12A7:Ce3+, Tb3+ phosphor shows intense green emissions located at 543 nm assigning to 5D4-7F5 transitions of Tb3+ ions, and weak blue emissions centered at 434 nm due to the transitions of Ce3+ 5d-4f. The photoluminescence (PL) intensity of Ce3+ decrease with increasing Tb3+ concentration, indicating the effective energy transfer (ET) occurred from Ce3+ to Tb3+ in C12A7:Ce3+, Tb3+. The ET efficiency between Ce3+ and Tb3+ in the optimum composition reaches to 99%. Based on Dexter's ET theory, we have demonstrated that the efficient ET is a resonant type via dipole-dipole mechanism with an energy transfer critical distance of 4.02 A. Our results suggested that C12A7:Ce3+, Tb3+ phosphor would be a promising green-emitting phosphor for UV-converting white light-emitting diodes. PMID:22413329

Liu, X L; Liu, Y X; Yan, D T; Zhu, H C; Liu, C G; Xu, C S

2011-11-01

316

Synthesis and luminescence properties of Ce 3+ doped nanoporous 12CaO·7Al 2O 3 powders and ceramics  

NASA Astrophysics Data System (ADS)

Ce 3+ doped nanoporous 12CaO·7Al 2O 3 (C12A7) was synthesized using the self-propagating combustion method and solid state reaction. Ceramics of high density were produced using the melt-solidification process in a carbon crucible. The obtained samples were characterized using XRD and SEM methods and studied by means of low temperature time resolved luminescence under laser and synchrotron radiation excitation. It was shown that the Ce 3+ ion in C12A7 emits broad-band 5d-4f luminescence peaked at ˜3.0 eV. The decay curves of Ce 3+ emission in the studied samples have complicated nature depending on the excitation energy with the main decay component of 20-30 ns life time, typical for parity and spin allowed transitions of Ce 3+. The emission of Ce 3+ ions is efficiently excited through the intra-centre as well as in the intrinsic absorption region of C12A7.

Tõldsepp, E.; Avarmaa, T.; Denks, V.; Feldbach, E.; Kirm, M.; Maaroos, A.; Mändar, H.; Vielhauer, S.

2010-06-01

317

Mineralogical effects on the detectability of the postperovskite boundary  

E-print Network

(Fp), calcium silicate perovskite (Ca-Pv), silica, calcium-ferrite-type aluminous (CF) phase, etc December 23, 2011 (received for review June 14, 2011) The discovery of a phase transition in Mg-silicateO, SiO2, FeO, Al2O3, CaO, Na2O, etc.), multiphase (magnesium silicate perovskite (Pv), ferropericlase

Rhoads, James

318

American Mineralogist, Volume 95, pages 188191, 2010 0003-004X/10/0001188$05.00/DOI: 10.2138/am.2010.3365 188  

E-print Network

.61, Na2O 0.55, CaO 0.28, TiO2 0.04, V2O3 0.02, sum 98.25, corresponding to an empirical formula of (Fe2, exsolution, zonation, coatings, pores) in minerals and revealing nanominerals and nanoparticles (Ma 2008

Ma, Chi

319

ac conductivity analysis for a metal core-silver orthosilicate shell nanostructure  

E-print Network

. Chakravortya Unit on Nano Science and Technology, Indian Association for the Cultivation of Science, Kolkata. INTRODUCTION Nanostructured materials have occupied the center stage of research in recent times because used was a melt-quenched glass of com- position 15 Na2O, 15 Li2O, 12 CaO, 3 Al2O3, and 55 SiO2 in mol

Macdonald, James Ross

320

An Approach to Geochemical and Protolith Features of the Mesozoic HP/LT Rocks in the Biga Peninsula, NW Turkey  

NASA Astrophysics Data System (ADS)

The Biga Peninsula in northwestern Anatolia is a tectonic mosaic comprised of different tectonic units which represented by continental and oceanic assemblages in different origin and ages. High-degree metamorphic rocks occur in the both Çamli ca metamorphics and Çetmi Group. HP eclogite/blueschists are associated with quartz-mica schist within the Çamli ca metamorphics. On the other hand, another HP eclogite/blueschist unit is associated with garnet-mica schist in the Çetmi Group. The host Çamli ca metamorphic rocks record only a single - stage greenschist - facies metamorphism and were juxtaposed with the high - grade metamorphic rocks along ductile - semi-brittle (?) strike - slip faults after the high degree metamorphism and during or after the low-grade metamorphism of the Çamli ca metamorphic unit. Major, trace and rare earth elements (REE) compositions of HP eclogite/blueschist and associated metasedimentary rocks from the Biga Peninsula have been determined to reveal their protolith, source area and tectonic setting. Whole-rock geochemistry for the HP eclogite/blueschist suggests that their protoliths were basalt with high TiO2 and K2O-Na2O content and Nb/Y ratios. Most HP metabasite samples plot in the tholeiitic basalt field. â?? REE abundances range from 47.55 to 107.4 ppm. Europium anomolies are variable (Eu/Eu*= 0.9-1.1) and generally small negative (average Eu/Eu*=1) which is implying weak plagioclase fractionation. REE pattern and trace element contents similar to typical MORB based on tectonic discrimination diagrams. The relatively high concentrations of CaO and low concentrations of K2O suggest that the protoliths were derived from a depleted source. Metasedimentary rocks coexisting with HP metamorphic rocks have different SiO2, Al2O3 and TiO2 values in the both Çamli ca metamorphics and Çetmi Group. Those of the Çamli ca metamorphics have high SiO2 and low Al2O3 and TiO2 values. However, those of the Çetmi Group have low SiO2 and high Al2O3 and TiO2 values. Major compositions of metasediments indicate that two schist units did not take place from the same source. The protolith of these schist units within the both Çamli ca metamorphics and Çetmi Group is arkose-subarkose and greywacke, respectively. Tectonic setting discrimination diagrams for quartz-mica schist, associated with HP rocks, indicate that developing on an active continental margin. On the other hand, garnet-mica schist is derived from the island arc and including contribution from a mafic source.

?engün, Firat; Yi?itba?, Erdinç; Onur Tunç, Ä.°Smail

2010-05-01

321

Archaean multiphase Porosozero sanukitoid pluton of the Kola region: petrological, geochronological and geochemical data  

NASA Astrophysics Data System (ADS)

The Porosozero sanukitoid intrusion is located in the greenstone belt of the Kolmozero-Voronja, north-eastern part Fennoscandian (Baltic) Shield. The Porosozero multiphase pluton was formed as a result of the 4 magmatic phases during the period ca. 60 million years. The main phase is represented by a differentiated series of gabbro-diorite - quartz monzodiorite - granodiorite - granite. The zircon TIMS ages of granodiorite and quartz monzodiorites are 2733±6 Ma and 2734±4 Ma, respectively. The second phase is composed of leucogranites formed during intrusion of the residual melt portion from intracrustal source. The age of zircon from leucogranite is 2712±6 Ma. The third phase is represented by the lamprophyre dykes with the zircon age 2680±8 Ma. The late pegmatite veins were formed during the fourth final phase. The volume relationships between the gabbro-diorite, quartz monzodiorites, granodiorites and granites are 5:55:27:13, respectively. The medium weighted composition of the initial melt, calculated from the rock compositions of the first phase is andesite (wt.%): SiO2 = 61.53, TiO2 = 0.58, Al2O3 = 15.74, Fe2O3 = 3.75, FeO = 3.07, MnO = 0.10, MgO = 3.06, CaO = 5.83, Na2O = 3.78, K2O = 2.37. The compositional variation is the result of fractional crystallization. The last magmas may have experienced some crustal contamination. All rocks of the first phase are enriched in Ba (500-800 ppm), Sr (450-700 ppm), K2O (1.8-3.2 wt. %), P2O5 (0.15-0.35), LREE [(La/Yb)N=15-23] and contain high concentrations of Cr (150-400 ppm) and Ni (60-140 ppm), possess high mg# values (0.45-0.65), and show a negative Nb-Ta anomaly. Sm-Nd isotopic data for sanukitoids indicate their formation from a mantle source enriched in LILE and LREE with ?Nd (2740) = +1.02 - +0.36, T(DM)=2.9-2.8 Ga. The Porosozero polyphasic pluton is similar to worldwide Archaean and Phanerozoic magmatic sanukitoide series. The Porosozero pluton formation is determined by the processes of mantle-crust interaction in suprasubduction conditions within the active continental margins. The high content of Ag and Au in rocks Porosozero pluton provides a general perspective for precious metals.

Kudryashov, Nikolai; Mokrushin, Artem; Petrovsky, Michail; Elizarov, Dmitry

2013-04-01

322

Geochemical characteristics of Mesoproterozoic clastic sedimentary rocks from the Chakrata Formation, Lesser Himalaya: implications for crustal evolution and weathering history in the Himalaya  

NASA Astrophysics Data System (ADS)

To evaluate the changes in the chemistry of upper continental crust during Precambrian time in the Himalaya, the oldest and best-preserved Mesoproterozoic clastic sedimentary rocks (pelites/shales and quartzites) from the Chakrata Formation, NW Lesser Himalaya, Uttar Pradesh have been analysed for major elements and a number of trace elements, including rare earth elements (REEs). When compared to post-Archean shales (for e.g. North American Shale Composite), the Chakrata pelites have high SiO 2, Al 2O 3, K 2O, Rb, Ba contents and low CaO, Fe 2O 3t, TiO 2, Sr, Sc, Ni and Cr concentrations. The REE abundances are high (up to 296 ppm) in pelites and reveal enriched LREE and depleted HREE patterns (La N/Yb N=7.9-11.1). Strong negative Eu anomalies are evident in the Chakrata pelites (Eu/Eu ?=0.46-0.58). The quartzites of the Chakrata Formation have high silica contents and low trace element abundances when compared to Phanerozoic sandstones. The chemical index of alteration values of these rocks ranges from 70 to 76, indicating intense weathering conditions in the source areas. Most pelites of the Chakrata Fm plot near the A-K line in the A-CN-K diagram which also suggests intense chemical weathering conditions. Major and trace element abundances and elemental ratios critical of provenance (e.g. high SiO 2/Al 2O 3, K 2O/Na 2O, La/Sc, Th/Sc, La/Yb and low Eu/Eu ? and Cr/Zr) suggest that the source rocks of these pelites were remarkably felsic in nature. The paleocurrent analyses reveal that the Chakrata pelites may have been derived from the granitoid rocks from the southerly direction (i.e. from Peninsular India). The geochemical similarities favour granitoid rocks from the Aravalli and Bundelkhand regions as the main source rocks for Chakrata sedimentary rocks.

Rashid, S. A.

2002-12-01

323

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

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

324

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)

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.

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

2012-12-01

325

Hydride ion as a two-electron donor in a nanoporous crystalline semiconductor 12CaO.7Al2O3.  

PubMed

The 12CaO.7Al2O3 (C12A7) crystal with a nanoporous lattice framework exhibits high electrical conductivity with an activation energy of approximately 1.5 eV when equilibrated in a hydrogen atmosphere above approximately 800 degrees C. The high conductivity is preserved in a quenched state below approximately 600 degrees C with a reduced activation energy of approximately 0.8 eV. Such complex behavior in electrical conductivity is associated with incorporation of hydride ions (H-) in cages of the lattice framework. Electromotive force measurements reveal that the major carrier for the conductivity is electron with a small contribution by proton (H+), ruling out the possibility of direct intercage migration of the H- ion. A combination of these observations with the ab initio calculations leads to the conclusion that the electrons are thermally generated from the H- ion by the dissociation into two electrons and an proton, which is further converted to an OH- ion via reaction with an extraframework oxide ion (O2-). The energy difference between the initial (H- + O2-) and the final (2e- + OH-) states as evaluated by the theoretical calculation is as small as approximately 1 eV, which agrees well with an experimentally obtained enthalpy change, approximately 1.4 eV. Thus, internal equilibration between the extraframework hydrogen and the oxygen species is responsible for the thermal generation of the carrier electron. It is also suggested that the same conductive (2e- + OH-) state is reached by the photoirradiation of H- -containing C12A7. In this case the photoionization of H- forms an electron and an Ho atom, which then forms an OH- ion and another electron with thermal assistance. The persistence of photoinduced conductivity is explained by the slow kinetics of the reverse process at room temperature. PMID:16375369

Hayashi, Katsuro; Sushko, Peter V; Shluger, Alexander L; Hirano, Masahiro; Hosono, Hideo

2005-12-22

326

Preparation and Characterization of Storage and Emission Functional Material of Cs2O-doped 12CaO·7Al2O3  

NASA Astrophysics Data System (ADS)

We provides a novel approach to generate low-temperature atomic oxygen anions (O-) emission using the cesium oxide-doped 12CaO·7Al2O3 (Cs2O-doped C12A7). The maximal emission intensity of O- from the Cs2O-doped C12A7 at 700 °C and 800 V/cm reached about 0.54 ?A/cm2, which was about two times as strong as that from the un-doped C12A7 (0.23 ?A/cm2) under the same condition. The initiative temperature of the O- emission from the Cs2O-doped C12A7 was about 500 °C, which was also much lower than the initiative temperature from the un-doped C12A7 (570 °C) in the given field of 800 V/cm. High pure O- emission close to 100% could be obtained from the Cs2O-doped C12A7 under the lower temperature (<550°C). The emission features of the Cs2O-doped C12A7, including the emission distribution, temperature effect, and emission branching ratio have been investigated in detail and compared with the un-doped C12A7. The structure and storage characteristics of the resulting material were also investigated via X-ray diffraction and electron paramagnetic resonance. It was found that doping Cs2O to C12A7 will lower the initiative emission temperature and enhance the emission intensity.

Ning, Shen; Shen, Jing; Li, Xing-long; Li, Quan-xin

2011-06-01

327

Bioactive ceramics prepared by sintering and crystallization of calcium phosphate invert glasses.  

PubMed

Novel glass-ceramics were synthesized via sintering and crystallization by heating powder compacts of SiO2-free calcium phosphate invert glasses of 60CaO x 30P2O5 x 7Na2O x 3TiO2 or 60CaO x 30P2O5 x 7Na2O x 3MgO at 800-850 degrees C in air. The glass-ceramics were relatively dense materials consisting of crystalline phases such as beta-Ca3(PO4)2 and beta-Ca2P2O7 with glassy phases. The compacts were densified by the viscous flow of the glassy phases while heating. By soaking in simulated body fluid at 37 degrees C, a calcium phosphate phase was formed newly on the surface of the glass-ceramic derived from 60CaO x 30P2O5 x 7Na2O x 3TiO2 glass, while the phase was not formed on that derived from 60CaO x 30P2O5 x 7Na2O x 3MgO glass: the former was implied to show bioactivity. Composition of the glassy phase as the matrix varies with the additives such as TiO2 and MgO, and the chemical properties of the phase influence the bioactivity of the glass-ceramics. The glass-ceramic derived from 60CaO x 30P2O5 x 7Na2O x 3TiO2 glass has relatively high fracture toughness of K(IC) approximately 2 MPa m(0.5) and bending strength of 100-120 MPa. PMID:10454013

Kasuga, T; Sawada, M; Nogami, M; Abe, Y

1999-08-01

328

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

E-print Network

and B. Redding, "Multimode Optical Fiber Spectrometer", International patent application. Book and book-loss modes in deformed microdisks, Chapter 4 in "Trends in Nano- and Micro-Cavities," ed. O'Dae Kwon ultralow-loss modes in deformed microdisks", Chapter 4 in "Trends in Nano- and Micro-Cavities", ed. O' Dae

Cao, Hui

329

Curriculum Vitae Hui Cao 1 Hui Cao June 6, 2010  

E-print Network

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

Cao, Hui

330

Effects of CaF2 vis-a-vis TiO2 as nucleating agent in SiO2-Al2O3-CaO glass-ceramics  

NASA Astrophysics Data System (ADS)

The independent effects of CaF2 and TiO2 on the glass-ceramics based on SiO2-Al2O3-CaO system have been investigated. The crystallization behavior, microstructure, mechanical properties and chemical resistance of the glass-ceramics were studied by Differential Thermal Analysis (DTA), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), FTIR, mechanical and chemical resistance measurements. The CaF2 containing glass ceramics are found to be much superior to that of TiO2 containing glass ceramics on the basis of sintering strength, mechanical and chemical properties.

Mukherjee, Debasis Pradip; Datta, Tanmoy; Das, Sudip Kumar

2013-06-01

331

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

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

332

Photoacoustic studies of xCr2O3(1 - x)[2 P2O5· Na2O] glasses  

NASA Astrophysics Data System (ADS)

Photoacoustic and UV-VIS spectroscopy, magnetic susceptibility and electron paramagnetic resonance measurements have been performed on soda-phosphate glasses in order to explain the changes in the valence states of Cr and the structure of the Cr 2O 3 incorporated in these glasses.

Barbu, A.; Bratu, I.; Ardelean, I.; Cozar, O.

1995-04-01

333

Boson mode, Medium Range Structure and Intermediate Phase (IP) in (Na2O)x(B2O3)1-x glasses  

NASA Astrophysics Data System (ADS)

Raman scattering of titled glasses are examined using a T64000 Dispersive system. Scattering strengths of the Boson mode (40 cm-1, 70 cm-1) and the Boroxyl ring (BR) mode (808 cm-1) are found to decrease with increasing x at the same rate in the 0 < x < 20% soda range. Apparently, the 2D character of BRs embedded in a 3D network gives rise to the Boson mode.ootnotetextM. Flores-Ruiz and G. Naumis, PRB, 2011. 83: p. 184204 The triad of modes (705, 740, 770 cm-1) near the 808 cm-1 mode are found to display a maximum in scattering strength near x = 37% (705 cm-1), 33% (740 cm-1) and 25% (770 cm-1), suggesting that these are also ring modes of Na-tripentaborate (STPB), Na-diborate (SDB) and Na-triborate (STB) super-structures. Variations in Raman scattering strengths also suggest that STB percolate near x = 20%, the stress transition, while the STPB and SDTB percolate near x = 40%, the rigidity transition. These transitions were inferred from m-DSC experiments that show an intermediate phase in the 20% < x < 40% range in dry and homogeneous glasses.

Vignarooban, K.; Boolchand, P.; Micoulaut, M.; Malki, M.

2012-02-01

334

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

Microsoft Academic Search

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

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

2007-01-01

335

In vivo behavior of bioactive phosphate glass-ceramics from the system P2O5-Na2O-CaO containing TiO2.  

PubMed

Soda lime phosphate bioglass-ceramics with incorporation of small additions of TiO2 were prepared in the metaphosphate and pyrophosphate region, using an appropriate two-step heat treatment of controlled crystallization defined by differential thermal analysis results. Identification and quantification of crystalline phases precipitated from the soda lime phosphate glasses were performed using X-ray diffraction analysis. Calcium pyrophosphate (beta-Ca2P2O7), sodium metaphosphate (NaPO3), calcium metaphosphate (beta-Ca(PO3)2), sodium pyrophosphate (Na4P2O7), sodium calcium phosphate (Na4Ca(PO3)6) and sodium titanium phosphate (Na5Ti(PO4)3) phases were detected in the prepared glass-ceramics. The degradation of the prepared glass-ceramics were carried out for different periods of time in simulated body fluid at 37 degrees C using granules in the range of (0.300-0.600 mm). The released ions were estimated by atomic absorption spectroscopy and the surface textures were measured by scanning electron microscopy. Evaluation of in vivo bioactivity of the prepared glass-ceramics was carried through implanting the samples in the rabbit femurs. The results showed that the addition of 0.5 TiO2 mol% enhanced the bioactivity while further increase of the TiO2 content decreased the bioactivity. The effect of titanium dioxide on the bioactivity was interpreted on the basis of its action on the crystallization process of the glass-ceramics. PMID:17701314

Monem, Ahmed Soltan; ElBatal, Hatem A; Khalil, Elsayed M A; Azooz, Moenis A; Hamdy, Yousry M

2008-03-01

336

Polyphase growth of garnet in eclogite from the Hong'an orogen: Constraints from garnet zoning and phase equilibrium  

NASA Astrophysics Data System (ADS)

Major and trace element profiles as well as mineral inclusions were analyzed in garnets from massive and foliated eclogites from the low-T/high-P eclogite-facies zone in the Hong'an orogen, China. Garnets in the two types of eclogites show different core-rim zoning and mineral inclusions. At least two stages of garnet growth are evident for most garnet grains. Garnets in the massive eclogite contain abundant mineral inclusions such as quartz, chlorite, amphibole, rutile and phengite in cores, but only a few mineral inclusions such as quartz, rutile and titanite in rims. These garnet grains exhibit increasing MgO but decreasing CaO and REE contents from core to rim. Together with pseudosection calculations it is suggested that hydrous minerals such as chlorite, epidote and amphibole were probably the major reactants for the growth of garnet cores during prograde subduction, whereas the growth of garnet rims involves amphibole breakdown and/or dissolution of previously formed garnet. On the other hand, garnets in the foliated eclogite exhibit nearly constant MgO, decreasing MnO but increasing CaO and heavy REE contents (HREE) from core to rim. Along with pseudosection calculations it is inferred that the decomposition of epidote would consistently contribute to the growth of garnet core and rim. This is also supported by epidote zoning in matrix, with the occurrence of low-jadeite omphacite inclusions in the core and a few rutile inclusions in the rim. The enrichment of light REE (LREE) and depletion of HREE in the epidote rim relative to the core indicate that the epidote rim was recrystallized in equilibrium with the garnet rims. For protolith compositions, the foliated eclogite shows higher SiO2, Na2O, K2O and MgO contents but lower Al2O3, Fe2O3 and TiO2 contents than the massive eclogite. Along with phase equilibrium modeling, it is concluded that the differences in the protolith compositions of eclogites primarily dictate the differences in the garnet zoning patterns and the mineral assemblages of matrix and inclusions. The decomposition of hydrous minerals such as chlorite, amphibole and epidote is necessary for garnet growth during subduction-zone metamorphism.

Zhou, Li-Gang; Xia, Qiong-Xia; Zheng, Yong-Fei; Hu, Zhaochu

2014-10-01

337

Geochemistry and shock petrography of the Crow Creek Member, South Dakota, USA: Ejecta from the 74-Ma Manson impact structure  

USGS Publications Warehouse

The Crow Creek Member is one of several marl units recognized within the Upper Cretaceous Pierre Shale Formation of eastern South Dakota and northeastern Nebraska, but it is the only unit that contains shock-metamorphosed minerals. The shocked minerals represent impact ejecta from the 74-Ma Manson impact structure (MIS). This study was aimed at determining the bulk chemical compositions and analysis of planar deformation features (PDFs) of shocked quartz; for the basal and marly units of the Crow Creek Member. We studied samples from the Gregory 84-21 core, Iroquois core and Wakonda lime quarry. Contents of siderophile elements are generally high, but due to uncertainties in the determination of Ir and uncertainties in compositional sources for Cr, Co, and Ni, we could not confirm an extraterrestrial component in the Crow Creek Member. We recovered several shocked quartz grains from basal-unit samples, mainly from the Gregory 84-21 core, and results of PDF measurements indicate shock pressures of at least 15 GPa. All the samples are composed chiefly of SiO2, (29-58 wt%), Al2O3 (6-14 wt%), and CaO (7-30 wt%). When compared to the composition of North American Shale Composite, the samples are significantly enriched in CaO, P2O5, Mn, Sr, Y, U, Cr, and Ni. The contents of rare earth elements (REE), high field strength elements (HFSE), Cr, Co, Sc, and their ratios and chemical weathering trends, reflect both felsic and basic sources for the Crow Creek Member, an inference, which is consistent with the lithological compositions in the environs of the MIS. The high chemical indices of alteration and weathering (CIA' and CIW': 75-99), coupled with the Al2O3-(CaO*,+Na2O -K2O (A-CN'-K) ratios, indicate that the Crow Creek Member and source rocks had undergone high degrees of chemical weathering. The expected ejecta thicknesses at the sampled locations (409 to 219 km from Manson) were calculated to range from about 1.9 to 12.2 cm (for the present-day crater radius of Manson), or 0.4 to 2.4 cm (for the estimated transient cavity radius). The trend agrees with the observed thicknesses of the basal unit of the Crow Creek Member, but the actually observed thicknesses are larger than the calculated ones, indicating that not all of the basal unit comprises impact ejecta. ?? Meteoritical Society, 2004.

Katongo, C.; Koeberl, C.; Witzke, B.J.; Hammond, R.H.; Anderson, R.R.

2004-01-01

338

Crystallization of tholeiitic basalt in Alae Lava Lake, Hawaii  

USGS Publications Warehouse

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.

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

1966-01-01

339

Time constraints on the inversion of the tectonic regime in the northern margin of the North China Craton: Evidence from the Daqingshan granites  

NASA Astrophysics Data System (ADS)

The Daqingshan granites are located in a late Mesozoic tectono-magmatic belt at the northern margin of the North China Craton (NCC), and include the Deshengying, Xinisubei, Gulouban, and Kuisu plutons. Ion probe U-Pb zircon dating indicates that the granites were emplaced at 131 ± 1, 140 ± 4, 145 ± 1, and 142 ± 2 Ma, respectively. All of the granites are alkali- and potassium-rich, with high SiO2 (73.2-76.7 wt.%), K2O (4.50-5.57 wt.%), Na2O (3.60-4.93 wt.%), and K2O/Na2O (0.99-1.49), and low Al2O3 (12.3-14.5 wt.%), CaO (0.45-0.79 wt.%), and MgO (?0.12 wt.%). The granites are light rare earth element enriched ([La/Yb]N = 5.6-48.7). The Xinisubei and Gulouban monzogranites and the Kuisu mylonitic monzogranite have small Eu anomalies (?Eu = 0.65-1.23), low Zr + Nb + Ce + Y (132-321 ppm), and exhibit a negative correlation between P2O5 and SiO2 contents, which are characteristic of highly fractionated I-type granites with a post-collisional origin. The Deshengying monzogranite is distinctive in being an aluminous A-type granite as evidenced by high 10,000 × Ga/Al (>2.6) and Zr + Nb + Ce + Y (312-532 ppm), low Ba and Sr, marked negative Eu anomalies (?Eu = 0.08-0.20), strong Ba, Sr, P, and Ti depletions, and an absence of alkali minerals. This granite was probably produced by partial melting of continental crust heated by hot mantle-derived magmas during crustal extension. The Deshengying monzogranite represents a post-kinematic pluton emplaced into the Daqingshan fold-and-thrust belt, whereas the Kuisu mylonitic monzogranite is a syn-kinematic pluton intruded along the Hohhot detachment fault. It is evident that the Daqingshan area experienced a change from a compressional to an extensional tectonic regime during 145-140 Ma. The post-orogenic collapse may have resulted in extension of the upper continental crust. Subsequently, as the thrust-detachment system became inactive, the lower crust of the NCC underwent modification and melting from 131 Ma. We conclude that the Early Cretaceous tectonic evolution of the Daqingshan area was caused by post-orogenic collapse and melting of the lower crust of the NCC. Delamination of the lower crust in the northern NCC resulted in crustal extension and asthenospheric upwelling, which produced A-type granites. As such, melting of the lower crust in the northwestern part of the NCC took place as early as the late Mesozoic.

Meng, Qingpeng; He, Yuankai; Zhang, Wen; Zheng, Rongguo; Xu, Cao; Zhang, Zhaoyu; Wu, Tairan

2014-01-01

340

Glass and mineral analyses from first deposits of Peach Spring Supereruption (SW USA) illuminate initial tapping of a zoned magma chamber  

NASA Astrophysics Data System (ADS)

The Peach Spring supereruption (18.78±0.02 Ma) was sourced from Silver Creek caldera in the southern Black Mountains, Arizona (Ferguson et al. in press). The resulting ignimbrite, the Peach Spring Tuff (PST), blanketed >32,000 km2 of Arizona, California, and Nevada (Buesch, 1993). Underlying the ignimbrite is a thin (? 1m thick) basal layered deposit that consists of texturally distinct layers 1a-e (Valentine et al. 1989) and is present up to ~100 km from the source caldera. Basal layered deposits contain the first material erupted during the PST supereruption, preceding the main eruption event. Petrography and geochemistry of minerals and pumice clasts from basal layered deposits collected ~15-100 km from the caldera, combined with a survey of glass and crystal compositions from both outflow and basal deposits, permit (1) comparisons with the overlying ignimbrite, and (2) insights into the initial stages of the supereruption and extraction of magma from the chamber. Pumice clasts from a pumice-rich layer (1a2) of the basal deposit were characterized by LA-ICPMS and SEM. Unaltered glass has a uniform high-Si rhyolite composition (76.7% SiO2, 13.0% Al2O3, 3.6% Na2O, 5.3% K2O, 0.6% FeO, <0.1% MgO, 0.6% CaO, 0.1% TiO2). Mildly altered glass is similar but has lower Na2O and higher K2O. Pumice clasts are relatively crystal poor (<10% phenocrysts) with an assemblage dominated by sanidine (~Or55Ab43An2), with lesser plagioclase (~Ab73An19Or8), minor hornblende and biotite, and accessory magnetite, sphene, zircon, chevkinite, and apatite; no quartz was identified. Initial LA-ICPMS results for glass reveal REE patterns with large negative Gd (0.21: i.e. U-shaped REE pattern) and Eu (0.31) anomalies, very low Ba and Sr (?10 ppm), and high Rb (~250 ppm). These compositions are essentially identical to those of the most common pumice from distal outflow ignimbrite, but very different from crystal-rich (>30%) trachyte pumice that dominates the intracaldera fill and is present at the tops of proximal outflow sections (Pamukcu et al. in press). A broader survey by EMP of minerals and glass shards from basal layered deposits and outflow ignimbrite (Buesch, 1993 and unpublished data, 1992) support the general conclusion that distal outflow is dominated by high-Si rhyolite, but demonstrate that trachyte is present throughout ignimbrite and basal deposits. Although SiO2 concentration is dominantly ~76-78 wt%, a small but persistent population ranges from ~66-72 wt%. Likewise, 6% (in layer 1a2) to 40% of all plagioclase in basal and outflow deposit samples is relatively calcic (An>27), indicating trachyte origin. The above data (1) confirm the existence of two compositions of erupted magma (phenocryst-poor, high-Si rhyolite, crystal-rich trachyte); (2) demonstrate that the initial eruption (basal layer) tapped the same magmas as the ignimbrite; and (3) reveal that, although rhyolite dominates outside the caldera, trachyte like that in intracaldera deposits was also tapped throughout the eruption. These relations are consistent with eruption from a vertically stratified magma chamber with trachyte (cumulate?) beneath rhyolite, but indicate that either chamber stratification was imperfectly developed or some magma from deeper levels was entrained throughout the eruption.

Mccracken, R. G.; Miller, C. F.; Buesch, D.; Gualda, G. A.; Covey, A.

2012-12-01

341

The Comparative Structural Study of Vitreous Matrices P2O5?MeO [MeO ? Li2O (M1) or CaO (M2)] Systems and xFe2O3(100-x)[P2O5?MeO] Glasses by Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

For getting information about the way in which the structural units presented in glass matrices P2O5?Li2O (M1) and P2O5?CaO (M2) are modifying with the substitutions Li2O 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 Fe2O3 content on the structure of M1 and M2 matrices was followed.

Andronache, C.

2010-01-01

342

Substitution of CaO by BaO to improve the microwave dielectric properties of CaO–Li 2O–Sm 2O 3–TiO 2 ceramics  

Microsoft Academic Search

Sintered CaO–Li2O3–Sm2O3–TiO2(16:9:12:63) composition (CLST) at 1325°C shows microwave dielectric properties: ?r=104.1, Q?f value=4320 GHz, and ?f=13.2 ppm\\/°C. When BaO is used to substitute CaO in the CLST composition to form CaO–BaO–Li2O–Sm2O3–TiO2=16?x:x:9:12:63 (x=2 and 4 for CBLST2 and CBLST4), the sintered CBLST2 and CBLST4 ceramics show coexistence of two phases, the perovskite CaO–Li2O3–Sm2O3–TiO2 (CLST) phase and BaSm2Ti4O12 (BST). As the BaO

Ying-Chung Chen; Ping-Shou Cheng; Cheng-Fu Yang; Wen-Cheng Tzou

2001-01-01

343

Characterization of 12CaO x 7Al2O3 doped indium tin oxide films for transparent cathode in top-emission organic light-emitting diodes.  

PubMed

12CaO x 7Al2O3, insulator (C12A7) doped indium tin oxide (ITO) (ITO:C12A7) films were fabricated using a radio frequency magnetron co-sputtering system with ITO and C12A7 targets. The qualitative and quantitative properties of ITO:C12A7 films, as a function of C12A7 concentration, were examined via X-ray photoemission spectroscopy and synchrotron X-ray scattering as well as by conducting atomic force microscopy. The work function of ITO:C12A7 (1.3%) films of approximately 2.8 eV obtained by high resolution photoemission spectroscopy measurements make them a reasonable cathode for top-emission organic light-emitting diodes. PMID:24245291

Jung, Chul Ho; Hwang, In Rok; Park, Bae Ho; Yoon, Dae Ho

2013-11-01

344

Disorder of O 2- ion and incorporation of O - and O2- radicals in nanoporous crystal 12CaO · 7Al 2O 3 studied by low-temperature heat capacity measurements  

NASA Astrophysics Data System (ADS)

Heat capacity of nanoporous crystal, 12CaO · 7Al 2O 3 (C12A7), was measured between 85 mK and 5 K under magnetic field up to 9 T. The heat capacity under zero magnetic field did not fit to the T3 law; the deviation was discussed in terms of the disorder of the O 2- ions in the subnanometer-sized cages in C12A7 lattice. Under magnetic field, the heat capacity showed a Schottky-type anomaly due to the Zeeman splitting of O - and O2- radicals ( S = 1/2) incorporated in the cages. The total concentration of O - and O2- radicals in the crystal was estimated to be 4.4 × 10 18 cm -3 (2.3 × 10 21 mol -1, 3.8 × 10 -3 mol mol -1).

Kohama, Yoshimitsu; Tojo, Takeo; Kawaji, Hitoshi; Atake, Tooru; Matsuishi, Satoru; Hosono, Hideo

2006-04-01

345

Natural weathering in dry disposed ash dump: Insight from chemical, mineralogical and geochemical analysis of fresh and unsaturated drilled cores.  

PubMed

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

Akinyemi, S A; Akinlua, A; Gitari, W M; Khuse, N; Eze, P; Akinyeye, R O; Petrik, L F

2012-07-15

346

Optimization of the thermodynamic properties and phase diagrams of P2O5-containing systems  

NASA Astrophysics Data System (ADS)

P2O5 is an important oxide component in the late stage products of numerous igneous rocks such as granites and pegmatites. Typically, P2O5 combines with CaO and crystallizes in the form of apatite, while in volatile-free conditions, Ca-whitlockite is formed. In spite of their interest, the thermodynamic properties and phase diagrams of P2O5-containg systems are not well known yet. In the case of the pure P2O5 for example, no experimental thermodynamic data are available for the liquid and the O and O' solid phases. As a result, we re-evaluated all the thermodynamic and phase diagram data of the P2O5 unary system [1]. Optimization of the thermodynamic properties and phase diagrams of the binary P2O5 systems was then performed including the Li2O-, Na2O-, MgO-, CaO-, BaO-, MnO-, FeO-, Fe2O3-, ZnO-, Al2O3-, and SiO2-P2O5 [2] systems. All available thermodynamic and phase equilibrium data were simultaneously reproduced in order to obtain a set of model equations for the Gibbs energies of all phases as functions of temperature and composition. In particular, the Gibbs energy of the liquid solution was described using the Modified Quasichemical Model [3-5] implemented in the FactSage software [6]. Thermodynamic modeling of the Li2O-Na2O-K2O-MgO-CaO-FeO-Fe2O3-Al2O3-SiO2 system, which include many granite-forming minerals such as nepheline, leucite, pyroxene, melilite, feldspar and spinel is currently in progress. [1] Jung, I.-H., Hudon, P. (2012) Thermodynamic assessment of P2O5. J. Am. Ceram. Soc., 95 (11), 3665-3672. [2] Rahman, M., Hudon, P. and Jung, I.-H. (2013) A coupled experimental study and thermodynamic modeling of the SiO2-P2O5 system. Metall. Mater. Trans. B, 44 (4), 837-852. [3] Pelton, A.D. and Blander, M. (1984) Computer-assisted analysis of the thermodynamic properties and phase diagrams of slags. Proc. AIME Symp. Metall. Slags Fluxes, TMS-AIME, 281-294. [4] Pelton, A.D. and Blander, M. (1986) Thermodynamic analysis of ordered liquid solutions by a modified quasichemical approach application to silicate slags. Metall. Trans. B, 17, 805-815. [5] A.D. Pelton, S.A. Decterov, G. Eriksson, C. Robelin and Y. Dessureault (2000) The modified quasichemical model - I Binary solutions. Metall. Mater. Trans. B, 31, 651-660. [6] C.W. Bale, P. Chartrand, S.A. Decterov, G. Eriksson, K. Hack, R. Ben Mahfoud, J. Melançon, A.D. Pelton and S. Petersen. (2002) FactSage Thermochemical Software and Databases. Calphad, 26, 189-228.

Hudon, Pierre; Jung, In-Ho

2014-05-01

347

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

E-print Network

. Average Si02, AI2 O3 and K2 O 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...

Trefry, John Harold

1977-01-01

348

Fabrication and photoluminescence properties of Ag0 and Ag0-Er3+ containing plasmonic glass nanocomposites in the K2O-ZnO-SiO2 system  

NASA Astrophysics Data System (ADS)

Here, we report the preparation of nano silver (Ag) and nano Ag-erbium (Ag-Er) co-embedded potassium-zinc-silicate based monolithic glass nanocomposites by a controlled heat-treatment process of precursor glasses. The nanocomposites were characterized by differential scanning calorimeter, dilatometer, UV-Visible absorption spectrophotometer, X-ray diffractometer and transmission electron microscope and spectroflurimeter. A strong surface plasmon resonance (SPR) band is observed around 430 nm in all the heat-treated glass nanocomposite samples due to the formation of Ag0 nanoparticles (NP). The Ag-glass nanocomposite samples display nearly 2-fold enhanced photoluminescence (PL) at 470 nm upon excitation at 290 nm until the size of the NP increases to the value equals to the mean free path of conduction electrons inside the particles. On contrary to this, the photoluminescence spectra of Er3+ ions exhibit a gradual decrease of NIR emission at 1540 nm due to 4I13/2 ? 4I15/2 transition under excitation at 523 nm in the heat-treated glass nanocomposites which happened due to excitation energy transfer of Er3+ ions to the Ag NP, acting as 'plasmonics diluents' for Er3+ ions. These nanocomposites have huge potential for various nanophotonic applications.

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

2014-11-01

349

Multi-component diffusion between molten SiO2 inclusions and surrounding felsic melt in an indochinite: Tektites as natural laboratories  

NASA Astrophysics Data System (ADS)

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

Macris, C. A.; Eiler, J. M.; Asimow, P. D.; Stolper, E. M.

2013-12-01

350

Chemical composition of Mount St. Helens volcanic ash  

Microsoft Academic Search

Volcanic ash samples from the May 18, 1980, Mount St. Helens eruption were analyzed for major, minor, and trace composition by a variety of analytical techniques. Results indicate that the basic composition of the ash consists of approximately 65% SiO2, 18% Al2O3, 5% FetO3, 2% MgO, 4% CaO, 4% Na2O, and 0.1% S. Thirty seven trace metals are reported including

H. E. Taylor; F. E. Lichte

1980-01-01

351

Fabrication and electron transport properties of epitaxial films of electron-doped 12CaO·7Al 2O 3 and 12SrO·7Al 2O 3  

NASA Astrophysics Data System (ADS)

Epitaxial growth and electron doping of 12CaO·7Al 2O 3 (C12A7) and 12SrO·7Al 2O 3 (S12A7) are reported. The C12A7 films were prepared on Y 3Al 5O 12 (YAG) single-crystal substrates by pulsed laser deposition at room temperature and subsequent thermal crystallization. X-ray diffraction patterns revealed the films were grown epitaxially with the orientation relationship of (001)[100] C12A7 || (001)[100] YAG. For S12A7, pseudo-homoepitaxial growth was attained on the C12A7 epitaxial layer. Upon electron doping, metallic conduction was achieved in the C12A7 film and the S12A7/C12A7 double-layered films. Analyses of optical absorption spectra for the S12A7/C12A7 films provided the densities of free electrons in each layer separately. Hall measurements exhibited larger electron mobility in the S12A7/C12A7 film than those in C12A7 and S12A7 films, suggesting free electrons may be accumulated at the S12A7/C12A7 interface due presumably to a discontinuity of the cage conduction bands.

Miyakawa, Masashi; Hiramatsu, Hidenori; Kamiya, Toshio; Hirano, Masahiro; Hosono, Hideo

2010-02-01

352

Large conductivity enhancement in polycrystalline 12CaO · 7Al 2O 3 thin films induced by extrusion of clathrated O 2- ions by hot Au + implantation and ultraviolet light illumination  

NASA Astrophysics Data System (ADS)

Large enhancement in electrical conductivity from <10 -10 S cm -1 to ˜4 × 10 -2 S cm -1 was achieved in polycrystalline 12CaO · 7Al 2O 3 (p-C12A7) thin films by hot Au + implantation at 600 °C and subsequent ultraviolet (UV) light illumination. Although the as-implanted films were transparent and insulating, the subsequent UV-light illumination induced persistent electronic conduction and coloration. A good correlation was found between the concentration of photo-induced F +-like centers (a cage trapping an electron) and calculated displacements per atom, indicating that the hot Au + implantation extruded free O 2- ions from the cages in the p-C12A7 films by kick-out effects and left electrons in the cages. These results suggest that H - ions are formed by the Au + implantation through the decomposition of preexisting OH - ions. Subsequent UV-light illumination produced F +-like centers via photoionization of the H - ions, which leads to the electronic conduction and coloration.

Miyakawa, M.; Hirano, M.; Kamiya, T.; Hosono, H.

2006-09-01

353

A multiphase strategy for realizing green cathodoluminescence in 12CaO·7Al2O3-CaCeAl3O7:Ce3+,Tb3+ conductive phosphor.  

PubMed

A multiphase strategy is proposed and successfully applied to make the insulating green phosphor CaCeAl3O7:Tb(3+) conductive in the form of 12CaO·7Al2O3-CaCeAl3O7:Ce(3+),Tb(3+). The phosphor shows bright green-light emission with a short lifetime (2.51 ms) under low-voltage electron beam excitation (3 kV). The green photo- and cathodoluminescence from (5)D4-(7)F(J) (J = 6, 5, 4, 3) transitions of Tb(3+) are significantly enhanced in comparison with pure C12A7:Tb(3+). It was confirmed that this enhancement is the consequence of the joint effects of energy transfer from Ce(3+) to Tb(3+) and broadening of the absorption spectrum of Ce(3+) due to the existence of multiple phases. In particular, under 800 V electron beam excitation, cathodoluminescence is improved by the modified electrical conductivity of the phosphor. When compared to the commercial Zn2SiO4:Mn(2+) with a long luminescence lifetime of 11.9 ms, this conductive green phosphor has greater advantage for fast displays. PMID:24061503

Liu, Xiuling; Liu, Yuxue; Yan, Duanting; Zhu, Hancheng; Liu, Chunguang; Liu, Weizhen; Xu, Changshan; Liu, Yichun; Zhang, Hong; Wang, Xiaojun

2013-12-14

354

Dielectric behavior of ternary mixtures: epoxy resin plus titanates (MgTiO3, CaTiO3 or BaTiO3) associated to oxides (CaO, MnO2 or ZnO)  

NASA Astrophysics Data System (ADS)

In the present work, we study the dielectric behavior of various ternary mixtures composed of epoxy resin (RE), of one of three different titanates (barium titanate, BaTiO3; calcium titanate, CaTiO3; magnesium titanate, MgTiO3) respectively with one of three oxides (calcium oxide, CaO; manganese dioxide, MnO2; zinc oxide, ZnO) using time domain reflectometry (TDR). The different composites are mixed at room temperature in different volume fractions keeping the epoxy resin at a constant volume fraction. Several mixture combinations are studied to see the oxides influence on the titanates dielectric behavior in the range from DC to 10 GHz. This is done through the experimental determination of the dielectric constant ?s. A noticeable effect has been recorded at the low frequency and which consists of an increase of this dielectric permittivity when growing the volume fraction of manganese dioxide. One meaningful point of this study is the lowest static conductivity value (8.017 × 10-3/(?m)) being reached with an incursion of 7.5% of MnO2 in a ternary mixture composed of RE, MgTiO3 and MnO2. In addition, the behavior obtained experimentally has been validated by the Lichtenecker modified model. This study interest lies on an application of these materials in microelectronics and particularly in telecommunication components manufacturing.

Bourouba, Nacerdine; Lalla, Khalfa; Martinez Jimenez, Juan Pablo; Bouzit, Nacerdine

2014-01-01

355

Glass-to-metal seals comprising relatively high expansion metals  

NASA Technical Reports Server (NTRS)

A glass suitable for glass-to-metal seals that has a resistance to attack by moisture and a high coefficient of linear thermal expansion is introduced. Linear expansion covers the range from 12 to 14 x 10 to the minus 6 C between room temperature and 500 C. The glass is essentially composed of, by molar percent, about 9% of K2O, about 10% of Na2O, about 70% of SiO2, about 6% Al2O3, and about 5% of MgO.

Hirayama, C. (inventor)

1974-01-01

356

Solution behavior of +4 cations in high silica melts: petrologic and geochemical implications  

Microsoft Academic Search

The saturation surfaces of rutile (TiO2), zircon (ZrSiO4), and hafnon (HfSiO4) were determined in anhydrous, peraluminous, high silica liquids of the system SiO2-Al2O3-Na2O-K2O as functions of silica concentration at 1,400° C in air. The saturation concentrations of TiO2, ZrO2, and HfO2 in rutile, zircon, and hafnon-saturated liquids, respectively, decrease smoothly and gradually as functions of increasing silica concentration. Thermodynamic analyses

Adam J. Ellison; Paul C. Hess

1986-01-01

357

Petrochemical characteristics of kimberlites and identification of their diamond-bearing potentiality  

Microsoft Academic Search

There has been found a distinct directional trend of kimberlites differing in ore-bearing potentiality with changing chemical\\u000a composition. The contents of MgO, NiO and Cr2O3 decrease gradualy while Na2O, K2O, Al2O3 and P2O5 increase considerably in the order of diamond-rich—diamond-poor—diamond-barren kimberlites. In general Fe2O3, FeO and TiO2 also show an increasing tendency. Therefore, the variations in chemical composition may be

Ruiyuan Zhong

1983-01-01

358

Magmatic source enrichment by slab-derived melts in a young post-collision setting, central Mindanao (Philippines)  

Microsoft Academic Search

Central Mindanao was the locus of a Pliocene (4–5Ma old) arc–arc collision event followed by basaltic to dacitic magmatism starting at 2.3Ma, representing the most voluminous volcanic field in the Philippines. Lava compositions range from calc-alkaline to shoshonitic. Adakites and Nb-enriched basalts are among the magmatic products. All the lavas are Na-rich (up to 4.88%), with Na2O\\/K2O ratios from 2.5

Fernando G. Sajona; René C. Maury; Manuel Pubellier; Jacques Leterrier; Hervé Bellon; Joseph Cotten

2000-01-01

359

High Quantum Efficiency of Nd3+ Ions in a Phosphate Glass System using the Judd-Ofelt Theory  

NASA Astrophysics Data System (ADS)

The optical properties of trivalent neodymium embedded in a P2O5-Al2O3-Na2O-K2O phosphate glass system, synthesized by the fusion method, are studied. Absorption, luminescence, lifetime, and Raman spectroscopy measurements were performed and the Judd-Ofelt theory was applied to determine optical parameters such as the quantum efficiency and the stimulated emission cross section of the Nd3+-doped glass system. This structure has high quantum efficiency at low Nd3+ concentrations, comparable to the efficiency of a commercial YAG:Nd3+ crystal. We discuss the mechanisms responsible for the high quantum efficiency observed in the proposed phosphate glass system.

Dantas, Noelio Oliveira; Serqueira, Elias Oliveira; Silva, Anielle Christine Almeida; Andrade, Acácio Aparecido; Lourenço, Sidney Alves

2013-08-01

360

Glass and glass-ceramic binder obtained from waste material for binding alundum abrasive grains into grinding wheels  

Microsoft Academic Search

The use of granular post-cupric slag (SiO2–Al2O3–CaO–MgO-(FeO,Fe2O3–K2O–Na2O)) as material for production of ceramic binders for abrasive tools was tested. Binder compositions of amorphous and crystalline structure (without any crystallisation catalyst) were composed on it basis. Using slag and conventional glass-making material as exclusive material for production, the binders enabling the bonding abrasive grains into grinding wheels with high physico-mechanical properties

D Herman

1998-01-01

361

Carboniferous-Permian extensive magmatism in the West Junggar, Xinjiang, northwestern China: its geochemistry, geochronology, and petrogenesis  

NASA Astrophysics Data System (ADS)

Located between the Tarim, Kazakhstan, and Siberian plates, the West Junggar terrane is a key component of the Paleozoic Central Asian Orogenic Belt (CAOB) with widespread late Paleozoic igneous rocks. In this paper, we report petrological, geochronological, and geochemical data for selected granitoids from the West Junggar. Based on geochronology, the I-type and A-type granites were formed predominantly at 347.9-319.0 Ma and at 321.4-290 Ma respectively. The early-stage I-type granites are characterized by low SiO2, Na2O, and K2O contents with Na2O/K2O ratios > 1 and are metaluminous to weakly-peraluminous. They are enriched in large ion lithophile elements (LILE) and in Sr but depleted in high field strength elements (HFSE), with (87Sr/86Sr)i ratios of 0.7028-0.7044 and ?Nd(t) values varying from + 5.74 to + 7.76. The late-stage I-type granites are characterized by low contents of Si2O and K2O and relatively high contents of FeO, MgO, and Na2O with Na2O/K2O ratios > 1, and are metaluminous to weakly-peraluminous. They are also enriched in LILE and depleted in HFSE with Eu anomalies, (87Sr/86Sr)i ratios of 0.703-0.704, and ?Nd(t) values varying from + 5.20 to + 8.00. The A-type granites have high SiO2 contents, high K calc-alkaline-shoshonitic affinities, positive ?Nd(t) values (5.76-7.77), and low initial 87Sr/86Sr ratios (0.7017-0.7045). Along with reported Sr-Nd isotopic data and regional geologic evidence the Early Carboniferous I-type granites are interpreted as products of partial melting of trapped oceanic crust triggered by underplated mantle wedge-derived basaltic magma; the Late Carboniferous-Early Permian I-type granites as derivatives of partially melted trapped oceanic crust; and the A-type granites as resulting from partial melting of trapped juvenile oceanic crust in an extensional regime. The A-type granitoids with high positive ?Nd(t) values and high Zr-saturation temperatures could be genetically related to a mantle plume or a regional-scale mantle upwelling in the CAOB.

Gao, Rui; Xiao, Long; Pirajno, Franco; Wang, Guo-can; He, Xin-xing; Yang, Gang; Yan, Sheng-wu

2014-09-01

362

Bulk, rare earth, and other trace elements in Apollo 14 and 15 and Luna 16 samples.  

NASA Technical Reports Server (NTRS)

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.

Laul, J. C.; Wakita, H.; Showalter, D. L.; Boynton, W. V.; Schmitt, R. A.

1972-01-01

363

Geochemical Constraints on the Mantle Source of the Upper Permian Emeishan Continental Flood Basalts, Southwestern China  

Microsoft Academic Search

The widespread Emeishan igneous province in southwestern China comprises the Emeishan continental flood basalts (ECFB) and associated mafie-ultramafic intrusions. The ECFB have variable SiO2, ranging from 43.6 to 52.1 wt%, Al2O3 from 5.0 to 12.6 wt%, and total alkali (K2O + Na2O) from 0.7 to 6.5 wt%. These oxides exhibit negative correlations with MgO (5.4 - 23.1 wt%), implying fractional

Xie-Yan Song; Mei-Fu Zhou; Zheng-Qian Hou; Zhi-Min Cao; Yun-Liang Wang; Youguo Li

2001-01-01

364

Study of natural glasses through their behaviour as membrane electrodes  

USGS Publications Warehouse

THE low-temperature chemical alteration of natural glass occurs in two stages: an initial stage in which it remains glassy but absorbs as much as 6 per cent water1, and a final stage in which devitrification to clay minerals, with release of silica, occurs2,3. During the first stage the composition of the glass may change, with gain of K2O and water and loss of Na2O (Smith, R. L., personal communication). This change is due to ion exchange. ?? 1962 Nature Publishing Group.

Truesdell, A.H.

1962-01-01

365

Geochemistry of oceanic igneous rocks - Ridges, islands, and arcs - With emphasis on manganese, scandium, and vanadium  

USGS Publications Warehouse

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.

Doe, B.R.

1997-01-01

366

Origin of two types of rhyolites in the Tarim Large Igneous Province: Consequences of incubation and melting of a mantle plume  

NASA Astrophysics Data System (ADS)

The Early Permian Tarim Large Igneous Province (LIP) in northwestern China contains a large area of silicic volcanics (~ 48,000 km2) which are spatially and temporally associated with mafic-ultramafic rocks. In order to understand the behavior of crust above a mantle plume, selected rhyolitic samples are investigated in terms of U-Pb zircon dating, geochemical and isotopic analyses. The Tarim rhyolites have high A/CNK ratios (= molar Al2O3/CaO + Na2O + K2O), Fe#, Ga/Al ratios, concentrations of high field strength elements (HFSEs) such as Zr and Nb, and rare earth elements (REEs), along with high zircon saturation temperatures (872-940 °C), typical of aluminous A-type granitoids. Two contrasting rock types have been recognized. The low Nb-Ta type rhyolites are mainly associated with the first phase of the Tarim flood basalt magmatism at ~ 290 Ma. They are characterized by negative Nb-Ta anomalies, low ?Nd(t) and ?Hf(t) values, and high 87Sr/86Sr(t) and ?18Ozircon values, consistent with a derivation from continental crustal source. The high Nb-Ta type rhyolites and their plutonic equivalents are associated with the second episode of Tarim magmatism (283-272 Ma). They are characterized by small negative to positive Nb-Ta anomalies, oceanic island basalt (OIB)-like trace element ratios, low 87Sr/86Sr(t) and high ?Nd(t) and ?Hf(t) values. These high Nb-Ta rhyolites are best interpreted as hybrid products of crystal fractionation of mafic magmas, coupled with crustal assimilation. The temporal and compositional evolution of the Tarim rhyolites reflects various extents of thermal and mass exchange between mantle-derived basaltic magma and crustal material above a mantle plume. When the plume head rises to the base of the Tarim craton, it first melts enriched components in the lithospheric mantle (~ 290 Ma), part of which may have ponded near the crust-mantle boundary and induced crustal anatexis leading to the formation of the low Nb-Ta type rhyolites. At ~ 280 Ma, large magma chambers and plumbing systems were formed due to increasing magma supply rate during decompression melting of the mantle plume. This led to the formation of a mafic-ultramafic and felsic association of which the high Nb-Ta type rhyolites are a part.

Liu, Hai-Quan; Xu, Yi-Gang; Tian, Wei; Zhong, Yu-Ting; Mundil, Roland; Li, Xian-Hua; Yang, Yue-Heng; Luo, Zhen-Yu; Shang-Guan, Shi-Mai

2014-09-01

367

Origin of hydrous fluids at seismogenic depth: Constraints from natural and experimental fault rocks  

NASA Astrophysics Data System (ADS)

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‰

Mittempergher, Silvia; Dallai, Luigi; Pennacchioni, Giorgio; Renard, François; Di Toro, Giulio

2014-01-01

368

Osumilite-(Mg): Validation as a mineral species and new data  

NASA Astrophysics Data System (ADS)

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.

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

369

Geochemistry and geodynamics of a Late Cretaceous bimodal volcanic association from the southern part of the Pannonian Basin in Slavonija (Northern Croatia)  

USGS Publications Warehouse

In this paper we present petrological and geochemical information on a bimodal basaltrhyolite suite associated with A-type granites of Late Cretaceous age from the South Pannonian Basin in Slavonija (Croatia). Basalts and alkali-feldspar rhyolites, associated in some places with ignimbrites, occur in volcanic bodies that are interlayered with pyroclastic and fossiliferous Upper Cretaceus sedimentary rocks. The petrology and geochemistry of the basalts and alkali-feldspar rhyolites are constrained by microprobe analyses, major and trace element analyses including REE, and radiogenic and stable isotope data. Basalts that are mostly transformed into metabasalts (mainly spilites), are alkalic to subalkalic and their geochemical signatures, particularly trace element and REE patterns, are similar to recent back-arc basalts. Alkali-feldspar rhyolites have similar geochemical features to the associated cogenetic A-type granites, as shown by their large variation of Na2O and K2O (total 8-9%), very low MgO and CaO, and very high Zr contents ranging between 710 and 149ppm. Geochemical data indicate an amphibole lherzolite source within a metasomatized upper mantle wedge, with the influence of upper mantle diapir with MORB signatures and continental crust contamination. Sr incorporated in the primary basalt melt had an initial 87Sr/86Sr ratio of 0.7039 indicating an upper mantle origin, whereas the 87Sr/86Sr ratio for the alkalifeldspar rhyolites and associated A-type granites is 0.7073 indicating an apparent continental crust origin. However, some other geochemical data favour the idea that they might have mainly originated by fractionation of primary mafic melt coupled with contamination of continental crust. Only one rhyolite sample appears to be the product of melting of continental crust. Geological and geodynamic data indicate that the basalt-rhyolite association was probably related to Alpine subduction processes in the Dinaridic Tethys which can be correlated with recent back-arc basins. The difference in geological and isotope ages between the bimodal basalt-rhyolite volcanism with A-type granite plutonism (72 Ma) and the final synkinematic S-type granite plutonism (48 Ma) can be taken as a lifetime of the presumed BARB system of the Dinaridic Tethys. Remnants of this presumed subduction zone can be traced for 300 km along the surrounding northernmost Dinarides.

Pamic, J.; Belak, M.; Bullen, T.D.; Lanphere, M.A.; McKee, E.H.

2000-01-01

370

Geochemical and technological characterization of clays of Corumbataí Formation, Paraná Basin, in the state of São Paulo, Brazil for the application in the ceramic industry.  

NASA Astrophysics Data System (ADS)

The Corumbataí Formation is a geological unit of the Paraná Basin comprises a range of predominantly argillaceous facies. These clays are important from an economic point of view, because they represent important mineral deposits suppliers of raw materials for the ceramic industry in the production of ceramic tiles.The study presents preliminary results of a research that aims to study the clays municipalities Tambaú, Ferreira and Santa Rosa of Viterbo in the State of São Paulo for their application and diversification of ceramic products. The methodology used was based on a detailed description of facies using the methodology in principles of analysis of Basin Miall (1984), followed by mineralogical identification by X-ray Diffraction, chemical analysis of major elements by X-ray Fluorescence and technological tests ceramic. According to the geological surveys of mines studied through columnar sections were identified the following lithofacies from base to top: Massive, Laminated, Intercalated and Altered. The mineralogy present on these lithofacies is composed by minerals: quartz, microclineo, albite, calcite, dolomite and hematite and by clay minerals illite, kaolinite and montmorillonite. The quartz represents the mineral more present in diffraction and occurs with d001 of 3.33Å in all lithofacies studied. The illite clay mineral represents the most frequent in studied samples presenting d 001 10Å in three conditions (natural, heated and treated with ethylene glycol) in which the blade was subjected to the analysis of X-ray diffraction, the presence of kaolinite or montmorillonite occurs or not in samples. It was observed a increased frequency of some minerals in the lithofacies studied, carbonates (calcite and dolomite), hematite and feldspar occurring in the intermediate portions of the profile with a predominance in lithofacies Intercalated. The illita clay mineral occurs throughout the profile, but with greater frequency in the lithofacies Massive and Laminated. The clay minerals kaolinite and montmorillonite occur in portions intermediate and top of the profiles studied in the intercalated and altered lithofacies. The chemical results of major elements by X-ray fluorescence confirmed the mineralogical results, with average values of 63.74 % of SiO2, 12.50 of Al2O3, 4.35% of of K2O, 0.45% of Na2O, 2,72% of CaO and 1,87 of MgO. The results chemical and mineralogical subsidized testing and ceramic formulations due to be executed later so defining the main applications of these clays in the production of ceramic products. The authors acknowledge the finantial support of Fundação de Amparo à Pesquisa do Estado de São Paulo-FAPESP, (Process, number 2012/24219-9).

Christofoletti, Sergio Ricardo; Torres Moreno, Maria Margarita; Batezelli, Alessandro; Zanardo, Antenor

2014-05-01

371

Wound dressings composed of copper-doped borate bioactive glass microfibers stimulate angiogenesis and heal full-thickness skin defects in a rodent model.  

PubMed

There is a need for better wound dressings that possess the requisite angiogenic capacity for rapid in situ healing of full-thickness skin wounds. Borate bioactive glass microfibers are showing a remarkable ability to heal soft tissue wounds but little is known about the process and mechanisms of healing. In the present study, wound dressings composed of borate bioactive glass microfibers (diameter = 0.4-1.2 ?m; composition 6Na2O, 8K2O, 8MgO, 22CaO, 54B2O3, 2P2O5; mol%) doped with 0-3.0 wt.% CuO were created and evaluated in vitro and in vivo. When immersed in simulated body fluid, the fibers degraded and converted to hydroxyapatite within ?7 days, releasing ions such as Ca, B and Cu into the medium. In vitro cell culture showed that the ionic dissolution product of the fibers was not toxic to human umbilical vein endothelial cells (HUVECs) and fibroblasts, promoted HUVEC migration, tubule formation and secretion of vascular endothelial growth factor (VEGF), and stimulated the expression of angiogenic-related genes of the fibroblasts. When used to treat full-thickness skin defects in rodents, the Cu-doped fibers (3.0 wt.% CuO) showed a significantly better capacity to stimulate angiogenesis than the undoped fibers and the untreated defects (control) at 7 and 14 days post-surgery. The defects treated with the Cu-doped and undoped fibers showed improved collagen deposition, maturity and orientation when compared to the untreated defects, the improvement shown by the Cu-doped fibers was not markedly better than the undoped fibers at 14 days post-surgery. These results indicate that the Cu-doped borate glass microfibers have a promising capacity to stimulate angiogenesis and heal full-thickness skin defects. They also provide valuable data for understanding the role of the microfibers in healing soft tissue wounds. PMID:25890736

Zhao, Shichang; Li, Le; Wang, Hui; Zhang, Yadong; Cheng, Xiangguo; Zhou, Nai; Rahaman, Mohamed N; Liu, Zhongtang; Huang, Wenhai; Zhang, Changqing

2015-06-01

372

Geochemical investigation of a semi-continuous extrusive basaltic section from the Deccan Volcanic Province, India: implications for the mantle and magma chamber processes  

NASA Astrophysics Data System (ADS)

Spatial and temporal variations in the geochemistry of an extrusive basaltic section of Deccan traps record progressive changes in mantle melting and crustal filtration and are relevant to understand continental flood basalt (CFB) magmatism. In the present work we have carried out detailed field, petrographic, density and magnetic susceptibility, and geochemical investigations on a small, semi-continuous extrusive section in the eastern Deccan Volcanic Province (DVP) to understand the role of shallow magma chambers in CFB magmatism. Four formations, Ajanta, Chikhli, Buldhana and Karanja crop out in the Gangakhed-Ambajogai area with increasing elevation. Our studies indicate that: (1) the Karanja Formation represents a major magma addition, as indicated by abrupt change in texture, increases in MgO, CaO, Ni, Cr, and Sr, and drastic decreases in Al2O3, Na2O, K2O, Rb, Ba, REE, bulk-rock density and magnetic susceptibility; (2) assimilation fractional crystallization, crystal-laden magmas, and accessory cumulus phases influence the trace element chemistry of Deccan basalts; (3) the predicted cumulate sequence of olivine gabbro-leucogabbro-oxide-apatite gabbro is supported by the observed layered series in a shallow magma chamber within the DVP; (4) the initial magma was saturated with olivine, plagioclase, and augite, and final the pressure of equilibration for the Gangakhed-Ambajogai section basalts is ~2 kbar (~6 km depth); (5) petrophysical parameters act as proxies for magmatic processes; (6) a small layer of oxide-rich basalts may represent the latest erupted pulse in a given magmatic cycle in the DVP; (7) parental basalts to some of the red boles, considered as formation boundaries, might represent small degree partial melts of the mantle; (8) SW Deccan basaltic-types continue into the eastern DVP; and (9) in addition to the magma chamber processes, dynamic melting of the mantle may have controlled DVP geochemistry. The present study underscores the importance of mapping specific stratigraphic intervals in limited areas to understand mantle and magma chamber processes relevant to CFB magmatism.

Vijaya Kumar, Kopparapu; Chavan, Chakradhar; Sawant, Sariput; Naga Raju, K.; Kanakdande, Prachiti; Patode, Sangita; Deshpande, Krishna; Krishnamacharyulu, S. K. G.; Vaideswaran, T.; Balaram, V.

2010-06-01

373

Aklimaite, Ca4[Si2O5(OH)2](OH)4 · 5H2O, a new natural hydrosilicate from Mount Lakargi, the Northern Caucasus, Russia  

NASA Astrophysics Data System (ADS)

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.

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

374

Hillesheimite, (K,Ca,?)2(Mg,Fe,Ca,?)2[(Si,Al)13O23(OH)6](OH) · 8H2O, a new phyllosilicate mineral of the Günterblassite group  

NASA Astrophysics Data System (ADS)

A new mineral, hillesheimite, has been found in the Graulai basaltic quarry, near the town of Hillesheim, the Eifel Mountains, Rhineland-Palatinate (Rheinland-Pfalz), Germany. It occurs in the late assemblage comprising nepheline, augite, fluorapatite, magnetite, perovskite, priderite, götzenite, lamprophyllite-group minerals, and åkermanite. Colorless flattened crystals of hillesheimite reaching 0.2 × 1 × 1.5 mm in size and aggregates of the crystals occur in miarolitic cavities in alkali basalt. The mineral is brittle, with Mohs' hard-ness 4. Cleavage is perfect parallel to (010) and distinct on (100) and (001). D calc = 2.174 g/cm3, D meas = 2.16(1) g/cm3. IR spectrum is given. Hillesheimite is biaxial (-), ? = 1.496(2), ? = 1.498(2), ? = 1.499(2), 2 V meas = 80°. The chemical composition (electron microprobe, mean of 4 point analyses, H2O determined from structural data, wt %) is as follows: 0.24 Na2O, 4.15 K2O, 2.14 MgO, 2.90 CaO, 2.20 BaO, 2.41 FeO, 15.54 Al2O3, 52.94 SiO2, 19.14 H2O, total is 101.65. The empirical formula is: K0.96Na0.08Ba0.16Ca0.56Mg0.58Fe{0.37/2+}[Si9.62Al3.32O23(OH)6][(OH)0.82(H2O)0.18] · 8H2O. The crystal structure has been determined from X-ray single-crystal diffraction data, R = 0.1735. Hillesheimite is orthorhombic, space group Pmmn, the unit-cell dimensions are: a = 6.979(11), b = 37.1815(18), c = 6.5296(15) Å; V=1694(3) Å3, Z = 2. The crystal structure is based on the block [(Si,Al)13O25(OH)4] consisting of three single tetrahedral layers linked via common vertices and is topologically identical to the triple layers in günterblassite and umbrianite. The strong reflections [ d Å ( I %)] in the X-ray powder diffraction pattern are: 6.857(58), 6.545(100), 6.284(53), 4.787(96), 4.499(59), 3.065(86), 2.958(62), 2.767(62). The mineral was named after its type locality. Type specimens are deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, registration number 4174/1.

Chukanov, N. V.; Zubkova, N. V.; Pekov, I. V.; Belakovskiy, D. I.; Schüller, W.; Ternes, B.; Blass, G.; Pushcharovsky, D. Yu.

2013-12-01

375

New soil composition data for Europe and Australia: demonstrating comparability, identifying continental-scale processes and learning lessons for global geochemical mapping.  

PubMed

New geochemical data from two continental-scale soil surveys in Europe and Australia are compared. Internal project standards were exchanged to assess comparability of analytical results. The total concentration of 26 oxides/elements (Al2O3, As, Ba, CaO, Ce, Co, Cr, Fe2O3, Ga, K2O, MgO, MnO, Na2O, Nb, Ni, P2O5, Pb, Rb, SiO2, Sr, Th, TiO2, V, Y, Zn, and Zr), Loss On Ignition (LOI) and pH are demonstrated to be comparable. Additionally, directly comparable data for 14 elements in an aqua regia extraction (Ag, As, Bi, Cd, Ce, Co, Cs, Cu, Fe, La, Li, Mn, Mo, and Pb) are provided for both continents. Median soil compositions are close, though generally Australian soils are depleted in all elements with the exception of SiO2 and Zr. This is interpreted to reflect the generally longer and, in places, more intense weathering in Australia. Calculation of the Chemical Index of Alteration (CIA) gives a median value of 72% for Australia compared to 60% for Europe. Element concentrations vary over 3 (and up to 5) orders of magnitude. Several elements (total As and Ni; aqua regia As, Co, Bi, Li, Pb) have a lower element concentration by a factor of 2-3 in the soils of northern Europe compared to southern Europe. The break in concentration coincides with the maximum extent of the last glaciation. The younger soils of northern Europe are more similar to the Australian soils than the older soils from southern Europe. In Australia, the central region with especially high SiO2 concentrations is commonly depleted in many elements. The new data define the natural background variation for two continents on both hemispheres based on real data. Judging from the experience of these two continental surveys, it can be concluded that analytical quality is the key requirement for the success of global geochemical mapping. PMID:22178529

Reimann, Clemens; de Caritat, Patrice

2012-02-01

376

A comparative evaluation of the CF:CS and CRS models in 210Pb chronological studies applied to hydrographic basins in Brazil.  

PubMed

The Constant Flux: Constant Sedimentation (CF:CS) and Constant Rate of Supply (CRS) of unsupported?excess (210)Pb models have been applied to a (210)Pb data set providing of eighteen sediments profiles sampled at four riverine systems occurring in Brazil, South America: Corumbataí River basin (S1=Site 1, São Paulo State), Atibaia River basin (S2=Site 2, São Paulo State), Ribeirão dos Bagres basin (S3=Site 3, São Paulo State) and Amazon River mouth (S4=Site 4, Amapá State). These sites were chosen for a comparative evaluation of the performance of the CF:CS and CRS models due to their pronounced differences on the geographical location, geological context, soil composition, biodiversity, climate, rainfall, and water flow regime, among other variable aspects. However, all sediments cores exhibited a common denominator consisting on a database built from the use of the same techniques for acquiring the sediments major chemical composition (SiO2, Al2O3, Na2O, K2O, CaO, MgO, Fe2O3, MnO, P2O5, TiO2 and LOI-Loss on Ignition) and unsupported/excess (210)Pb activity data. In terms of sedimentation rates, the performance of the CRS model was better than that of the CF:CS model as it yielded values more compatible with those expected from field evidences. Under the chronological point of view, the CRS model always provided ages within the permitted range of the (210)Pb-method in the studied sites, whereas the CF:CS model predicted some values above 150 years. The SiO2 content decreased in accordance with the LOI increase in all cores analyzed and such inverse relationship was also tracked in the SiO2-LOI curves of historical trends. The SiO2-LOI concentration fluctuations in sites S1 and S3 also coincided with some Cu and Cr inputs in the drainage systems. PMID:25005051

Bonotto, D M; García-Tenorio, R

2014-09-01

377

Formation of primary kimberlite melts - Constraints from experiments at 6-12 GPa and variable CO2/H2O  

NASA Astrophysics Data System (ADS)

Liquidus phase relations were experimentally studied in model kimberlite melts at 6-12 GPa. Four starting materials were used with different CO2 and H2O contents but almost identical proportions of other components (~ 35 wt.% SiO2, 3 wt.% Al2O3, 10 wt.% FeO, 33 wt.% MgO, 15 wt.% CaO, 0.3 wt.% Na2O, and 1 wt.% K2O on a 100% volatile-free basis). The liquidus phase of the CO2 richest mixture (33 wt.% CO2 and no H2O) is coesite at P > 6-8 GPa and low-Ca pyroxene at lower pressures. In an H2O-free mixture with lower CO2 content (18 wt.%) low-Ca pyroxene is the main liquidus phase and coesite was never observed in the experimental products. The addition of water (mixtures with 10 wt.% H2O + 9 wt.% CO2 and 12 wt.% H2O + 5 wt.% CO2) depresses the liquidus temperature and expands the crystallization field of olivine. At high pressures (> 8 GPa), garnet crystallization dominates near-liquidus phase relations. Based on the experimental data, possible conditions of the simultaneous saturation of kimberlite melt with olivine + low-Ca pyroxene ± garnet were estimated. High-Ca pyroxene was never found in the near-liquidus assemblages despite the high-CaO compositions of the starting mixtures. It was shown that the supposed primary kimberlite melt can be in equilibrium with the garnet harzburgite assemblage at 6-8 GPa and variable volatile contents, from ~ 15 wt.% CO2 under anhydrous conditions to 20 wt.% H2O and low CO2. These conditions correspond to possible parameters of kimberlite magma generation by partial melting of carbonated garnet harzburgite in the lithospheric mantle. The primary CO2 content could be higher if the kimberlite magma was poorer in SiO2 (more ‘carbonatitic'). The maximum CO2 content is limited by the appearance of magnesite on the liquidus at 20-22 wt.%, which is much lower than CO2 solubility in kimberlite melt at 7-8 GPa (> 30 wt.%). The content of H2O in primary kimberlite magmas depends on the bulk H2O content in the source, because no hydrous phases are stable near the kimberlite liquidus.

Girnis, A. V.; Bulatov, V. K.; Brey, G. P.

2011-12-01

378

Geochemistry of K/T-boundary Chicxulub ejecta of NE-Mexico  

NASA Astrophysics Data System (ADS)

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).

Harting, M.; Deutsch, A.; Rickers, K.

2003-12-01

379

Geochemistry and U-Pb SHRIMP zircon chronology of granitoids and microgranular enclaves from Jhirgadandi Pluton of Mahakoshal Belt, Central India Tectonic Zone, India  

NASA Astrophysics Data System (ADS)

The northern part of Central India Tectonic Zone (CITZ) is delineated by an arc-shaped supracrustal belt commonly referred to as Mahakoshal Belt, which is considered as a product of intense rifting of sialic crust that occurred at ca 2400-2600 Ma. Several granitoid plutons intrude the Parsoi Formation of Mahakoshal Belt. Among these, an elliptical small stock-like granitoid body trending E-W is exposed in and around Jhirgadandi region of Mahakoshal Belt, referred herein as Jhirgadandi Pluton. It is composed of minor amount of mafic rocks (diorite) and predominant granitoids. Country-rock pelitic xenoliths and microgranular enclaves (ME) are commonly hosted in granitoids but are absent in diorite. The ME exhibit typical magmatic texture with a Bt(±Cpx ± Hbl)-Pl-Kf-Qtz-Mag-Ap assemblage, similar to that in host granitoids but with contrasting mineral proportions. Whole-rock molar Al2O3/(CaO + Na2O + K2O) (A/CNK) ratios of diorite (0.63-0.72), ME (0.69-1.21) and granitoids (0.83-1.05) suggest their nature largely metaluminous (I-type) to rarely peraluminous (S-type) granitoids. On most binary plots involving silica, two distinct compositional paths can be recognized; one formed by an array of differentiating diorite and ME, and another by fractionating granitoids gradually depleting in compatible elements. It is most likely that ME were generated by progressive and concurrent mixing of coeval pristine mafic (diorite) and granitoid magmas and fractionation processes. However, coherent and identical trace elements (except for Sr, Th, Y and Ni) and REE patterns for ME-granitoid pairs most likely suggest partial to near-complete chemical equilibration through varying degrees of diffusion process across the ME - partly crystalline host granitoid boundary. High-precision U-Pb SHRIMP zircon 206Pb/238U ages for ME (1758 ± 19 Ma) and host granitoid (1753 ± 9.1 Ma) from Jhirgadandi Pluton further support the notion that they were coeval. The obtained age (˜1750 Ma) of Jhirgadandi Pluton also points to the existence and role of Super-Columbian continental component in the evolution of Mahakoshal Belt of the CITZ.

Bora, Sita; Kumar, Santosh; Yi, Keewook; Kim, Namhoon; Lee, Tae Ho

2013-07-01

380

Experimental and Petrological Constraints on Lunar Differentiation from the Apollo 15 Green Picritic Glasses  

NASA Technical Reports Server (NTRS)

Phase equilibrium experiments on the most magnesian Apollo 15C green picritic glass composition indicate a multiple saturation point with olivine and orthopyroxene at 1520 C and 1.3 GPa (about 260 km depth in the moon). This composition has the highest Mg# of any lunar picritic glass and the shallowest multiple saturation point. Experiments on an Apollo 15A composition indicate a multiple saturation point with olivine and orthopyroxene at 1520 C and 2.2 GPa (about 440 km depth in the moon). The importance of the distinctive compositional trends of the Apollo 15 groups A, B, and C picritic glasses merits the reanalysis of NASA slide 15426,72 with modern electron microprobe techniques. We confirm the compositional trends reported by Delano (1979, 1986) in the major element oxides SiO2, TiO2, Al2O3, Cr2O3, FeO, MnO, MgO, and CaO, and we also obtained data for the trace elements P2O5, K2O, Na2O, NiO, S, Cu, Cl, Zn, and F. Petrogenetic modeling demonstrates that the Apollo 15 A-B-C glass trends could not have been formed by fractional crystallization or any continuous assimilation/fractional crystallization (AFC) process. The B and C glass compositional trends could not have been formed by batch or incremental melting of an olivine + orthopyroxene source or any other homogeneous source, though the A glasses may have been formed by congruent melting over a small pressure range at depth. The B compositional trend is well modeled by starting with an intermediate A composition and assimilating a shallower, melted cumulate, and the C compositional trend is well modeled by a second assimilation event. The assimilation process envisioned is one in which heat and mass transfer were separated in space and time. In an initial intrusive event, a picritic magma crystallized and provided heat to melt magma ocean cumulates. In a later replenishment event, the picritic magma incrementally mixed with the melted cumulate (creating the compositional trends in the green glass data set), ascended to the lunar surface, and erupted as a fire fountain. A barometer created from multiple saturation points provides a depth estimate of other glasses in the A-B-C trend and of the depths of assimilation. This barometer demonstrates that the Apollo 15 A-B-C trend originated over a depth range of approx.460 km to approx.260 km within the moon.

Elkins-Tanton, Linda T.; Chatterjee, Nilanjan; Grove, Timothy L.

2003-01-01

381

Parameterizations of calcic clinopyroxene—Melt trace element partition coefficients  

NASA Astrophysics Data System (ADS)

Semiempirical parameterizations of the values and trends of variation of Nernst trace element partition coefficient data for Ca-rich clinopyroxene (cpx/liquidD) are provided, applicable mainly to common terrestrial magmatic suites. cpx/liquidD data for most trace elements show significant variability which cannot be neglected when modeling melting and crystallization. The influence of pressure on cpx/liquidD is strong for many elements, particularly Na and Sr, which increase as pressure rises, and most high-field strength elements, which decrease with increasing pressure. Most cpx/liquidD values increase as temperature decreases, as wt % melt MgO, MgO# (MgO/MgO+FeOtotal), CaO, and FeO contents drop, as cpx molar Mg# (Mg/Mg+Fetotal) decreases, and as wt % melt SiO2 and Na2O+K2O increase. No clear trends are seen for variations of cpx/liquidD against melt H2O. For mafic melts, many elements show well-defined trends of cpx/liquidD increase as the clinopyroxene tetrahedral Al content (cpx Aliv) increases. Many cpx/liquidD are well correlated against cpx/liquidDTi, and many "near-neighbor" elements show good cpx/liquidD intercorrelations (e.g., Zr-Hf, U-Th, Nb-Ta, La-Ce, Yb-Lu). Cpx/liquidD profiles calculated from these parameterizations can constrain changes of D values during melting or crystallization. Cpx/liquidD for the rare earth elements were fit to the lattice strain model to derive fits that can reproduce the cpx/liquidDREE profile shapes (REE = rare earth elements). These fits indicate that cpx/liquidDREE for melts more evolved than picritic basalts cannot be modeled assuming that all REE are in octahedral coordination in a single M2 site, but also require sixfold partitioning into an M1 site for Lu-Yb-Tm-Er.

Bédard, Jean H.

2014-02-01

382

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)

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.

Lee, J.; Lee, I.; Lee, S.; Kim, J.

2010-12-01

383

Geochronology and geochemistry of late Paleozoic volcanic rocks on the western margin of the Songnen-Zhangguangcai Range Massif, NE China: Implications for the amalgamation history of the Xing'an and Songnen-Zhangguangcai Range massifs  

NASA Astrophysics Data System (ADS)

We here elucidate the tectonic evolution of the Xing'an and Songnen-Zhangguangcai Range massifs during the early Carboniferous-early Permian, based on zircon U-Pb dating and whole-rock geochemical analyses of volcanic rocks of the Songnen-Zhangguangcai Range Massif in the Sunwu area, Heilongjiang Province, NE China. Euhedral-subeuhedral zircons from three rhyolites and one dacite from the study area display fine-scale oscillatory growth zoning, indicating a magmatic origin. Zircon U-Pb dating by LA-ICP-MS indicates that these acidic volcanic rocks formed in the early Carboniferous-early Permian; i.e., early Carboniferous (~ 351 Ma), early late Carboniferous (~ 319 Ma), and early Permian (295-293 Ma). The early Carboniferous rhyolites exhibit chemical affinities to A-type rhyolites, implying an extensional environment. Their positive ?Hf(t) values (+ 8.67 to + 13.4 except for one spot of + 1.63) and Hf two-stage model ages (TDM2 = 562-988 Ma) indicate that the primary magma was possibly derived from partial melting of newly accreted continental crust. The early late Carboniferous rhyolites and dacites (~ 319 Ma) exhibit calc-alkaline peraluminous signature [molar Al2O3/(CaO + K2O + Na2O) ratio, or A/CNK = 1.04-1.22]. The ?Hf(t) values and TDM2 ages of zircons from the 319 Ma dacites are in the range of + 5.33 to + 9.32 and 907-1268 Ma, respectively, suggesting that the primary magma was derived from partial melting of newly accreted crust. The early Permian rhyolites (295-293 Ma) show chemical affinities to A-type rhyolites, implying an extensional tectonic environment; their positive ?Hf(t) values (+ 8.82 to + 13.8) and Hf two-stage model ages (484-743 Ma) indicate that the primary magma was derived from partial melting of newly accreted crust. Combined with the geochemical features of coeval igneous rocks from the eastern margin of the Xing'an Massif, these data reveal the late Paleozoic tectonic history and relationships of the Xing'an and Songnen-Zhangguangcai Range massifs, i.e., early Carboniferous westward subduction of the Paleo-Asian oceanic plate beneath the Xing'an Massif, followed by early late Carboniferous collision and amalgamation of microcontinental blocks, and early Permian post-collisional extension.

Li, Yu; Xu, Wen-Liang; Wang, Feng; Tang, Jie; Pei, Fu-Ping; Wang, Zi-Jin

2014-09-01

384

Geochemical, Mineralogical, and Sedimentological Investigation of Phosphorite and its Clay-Rich Mine Tailings from a Phosphate Mine, Togo, West Africa  

NASA Astrophysics Data System (ADS)

Clay-rich mine tailings from phosphate mine operations in Togo West, Africa present major environmental and economic problems. Options for reclamation and restoration of the tailings are limited and are fundamentally restricted due to poorly executed waste management. The major control on the bulk physical properties of the tailings is the mineralogy of the materials. Clay samples from raw phosphate mined were obtained to investigate its sedimentological geochemical, and bulk properties Tailings were also analyzed for similar properties. The phosphatic deposits are Eocene in age, 1 to 10s of meters thick and consist mostly of moderately to poorly sorted phosphatized pellets, formanifera, and other bioclastic debris. Attapulgite occurs interstitially. Moisture contents of clays from the raw phosphate varies from 4.00 to 7.11 wt%. Francolite is the main mineral phase present in the samples analyzed. Geochemically, the rocks show significant enrichment in P2O5 and CaO. P2O5 concentrations vary from approximately 29 to 35.78 wt%. A strong correlation (r2 = 0.92) occurs between CaO and P2O5 abundances indicating that apatite is a major control on the phosphate. A number of heavy metal elements and trace elements occur. Cr, V, Ni, Cu, and Cd are interpreted to be in phosphate minerals, largely apatite. Mean oxide compositions (wt %) are 31.27% P2O5, 43.74% CaO, 9.50% SiO2, 4.30% Al2O3, 2.96% Fe2O3, 0.11 % K2O, 0.19% TiO2, 0.02% MnO, 0.02% MgO, 0.02 % Na2O, and 6.12 % LOI (loss of ignition). Our analysis shows that Cd, U, Th, and F are incorporated into the francolite. We conclude that the phosphorites in Togo formed under oxic, shallow-water conditions where microbial populations assimilated phosphorus primarily from seawater and mediated precipitation of calcium fluroapatite during early digenesis at the sediment-water interface. Analysis of the mine tailings show that the purification process leads to the enrichment of certain metals (Cr, Cu, Ni, V, Zn, Ba, Sr, Fe, and Al) in the tailings due to their association with the clay minerals, whereas Cd, Th, and U are enriched in the purified apatite-rich product. Leaching tests show that the solubility of metals generally increases when salinity increases or when pH decreases. Thus, the processing of phosphorites with sea water and the dumping of phosphorite tailings into the sea represent a serious potential risk for the marine ecosystem and for human health through the food chain.

Rezaie Boroon, M.; Ramirez, P. C.; Gnandi, K.

2009-12-01

385

Binary, ternary and quaternary silicates of CaO, BaO and ZnO in high thermal expansion seals for solid oxide fuel cells studied by high-temperature X-ray diffraction (HT-XRD)  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer We examined the thermal expansion of various silicates of CaO, BaO and ZnO. Black-Right-Pointing-Pointer Thermal expansions were determined by dilatometry and high-temperature X-ray diffraction. Black-Right-Pointing-Pointer High-temperature X-ray diffraction enabled to determine anisotropic thermal expansion. Black-Right-Pointing-Pointer CaSiO{sub 3}, Ca{sub 3}Si{sub 2}O{sub 7} and BaCa{sub 2}Si{sub 3}O{sub 9} exhibit the highest thermal expansion. Black-Right-Pointing-Pointer CaSiO{sub 3}, Ca{sub 3}Si{sub 2}O{sub 7} and BaCa{sub 2}Si{sub 3}O{sub 9} are suitable as components in high temperature seals. -- Abstract: Gas-tight seals based on glasses suitable for joining of materials with high thermal expansion coefficients are for example required for solid-oxide fuel cells. If these seals are to be used at high temperatures, they can only be fabricated from glasses which enable the crystallization of phases with high thermal expansion coefficients. This paper reports on some components from systems suitable for high thermal expansion seals: binary calcium silicates, CaSiO{sub 3}, Ca{sub 3}Si{sub 2}O{sub 7} and Ca{sub 2}SiO{sub 4} zinc silicates, Zn{sub 2}SiO{sub 4}, ternary silicates of BaO, CaO and ZnO, BaCa{sub 2}Si{sub 3}O{sub 9}, Ca{sub 2}ZnSi{sub 2}O{sub 7}, and one quaternary silicate, Ba{sub 2}CaZn{sub 2}Si{sub 6}O{sub 17,} studied by high-temperature X-ray diffraction. Only CaSiO{sub 3}, Ca{sub 3}Si{sub 2}O{sub 7} and BaCa{sub 2}Si{sub 3}O{sub 9} exhibit thermal expansion coefficients in the range suitable for high thermal expansion seals of 11.2-11.8 Multiplication-Sign 10{sup -6} K{sup -1} (100-800 Degree-Sign C). The thermal expansions strongly depend on the respective crystallographic axis. The coefficient of thermal expansion of a sealing glass is not only affected by the thermal expansions of the crystalline phases, but also by that of the residual glassy phase as well as by the elastic properties. The phase formation should carefully be controlled also with respect to aging.

Kerstan, Marita; Mueller, Matthias [Otto-Schott-Institut, Jena University, Fraunhoferstr. 6, 07743 Jena (Germany)] [Otto-Schott-Institut, Jena University, Fraunhoferstr. 6, 07743 Jena (Germany); Ruessel, Christian, E-mail: ccr@rz.uni-jena.de [Otto-Schott-Institut, Jena University, Fraunhoferstr. 6, 07743 Jena (Germany)] [Otto-Schott-Institut, Jena University, Fraunhoferstr. 6, 07743 Jena (Germany)

2011-12-15

386

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

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)

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

387

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

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.

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

388

High to ultrahigh potassic alkaline volcanic belt along the Ankara-Erzincan suture (northern Turkey): new geochemical and Ar-Ar data constraining petrogenesis with implications for the late Cretaceous subduction of the Neotethys Ocean  

NASA Astrophysics Data System (ADS)

Remnants of some high- to ultrahigh-K alkaline volcanic rocks crop out as isolated small and discontinuous bodies along the Ankara-Erzincan suture belt in northern Turkey. These rocks are represented by leucite-bearing lavas (LB), basaltic andesites, trachytes, monzonite/syenites) and lamprophyres. Leucite-bearing rocks are small stocks, dikes and lava flows. Pebbles and blocks of the LB are found in the coeval volcanic debris avalanche deposits and volcanoclastic breccias. Leucite-bearing rocks are mainly phonotephrite, tephriphonolite, trachyandesite and basaltic trachyandesites (shoshonite) and have mineral assemblages of lct + cpx + ol + pl + Kfs + mag+ ap. Leucites were almost totally analcimized. Trachytes and monzonite/syenites, which are seen as small stocks and dikes, are characterized by amp + bt + pl + Kfs + spn + ap + opq paragenesis. Lamprophyres are mica-rich melanocratic dikes, and include cpx + mica (phlogopitic) + Kfs + ap + opq. Rarely leucite, olivine and plagioclase are also present. Ar-Ar data reveal that this volcanic activity occurred between 73.6±0.18 and 76.78±0.19 Ma, corresponding to latest Cretaceous. All the samples from the high- and ultrahigh-K volcanic belt are alkaline in nature. Leucite-bearing lavas are characterized by their MgO (2.70-5.81, av. 4.58 wt.%), K2O (0.79-4.81, av. 2.35 wt.%), Na2O (4.86-7.48, av. 3.58 wt.%) and K2O/Na2O (0.13-0.92, av. 0.42 wt.%). The low K2O and K2O/Na2O contents of these rocks are due to extensive analcimization of the leucites. Major oxide contents in lamprophyric rocks are 3.25-7.48 (MgO), 1.35-7.76 (K2O), 1.77-4.00 (Na2O) and 0.31-2.69 (K2O/Na2O). The silica content of these rocks are variable and range from 47.18-50.26 (wt.%) (LB) to 39.14-53.28 (lamprophyres). Based on their major element contents, these rocks are classified as plagioleucitites or ultrapotassic rocks of the active orogenic zones (Foley, 1992). Leucite-bearing rocks, lamprophyres and the trachytes (with their hypabyssal equivalents) display similar geochemical behavior. Their typical features are high LILE relative to HFSE, and Nb-Ta and Ti depletions on the P-MORB normalized plots. In the lamprophyre group, Hf and Zr depletions are also evident. Mg# for all the rock series are highly variable (34 - 60), implying that these rocks formed from evolved melts. Considering the Ar-Ar ages, Nb-Ta depletions, LILE enrichments, some inter-elemental ratios and the geological evolution of the Ankara-Erzincan suture belt, we conclude that the late Cretaceous alkaline high- to ultrahigh-K magmatic products are common in space, time and origin in this region. All the rock groups were derived from partial melting of lithospheric mantle modified by subduction-related fluids, and from the melting of the subducted crustal material. Additionally, lamprophyric melts were possibly generated from the melting of veined SCLM. Veins were probably rich in phlogopitic mica and clinopyroxene. We propose that this alkaline high- to ultrahigh-K volcanic belt is the product of subduction-related magmatism, and resulted from northerly subduction of the Neotethyan Ocean crust during the latest Cretaceous period.

Genc, S. Can; Gulmez, Fatma; Tuysuz, Okan; Karacik, Zekiye; Roden, Michael F.; Zeki Billor, M.; Hames, Willis E.

2013-04-01

389

Melting and subsolidus phase relations in peridotite and eclogite systems with reduced Csbnd Osbnd H fluid at 3-16 GPa  

NASA Astrophysics Data System (ADS)

Melting phase relations of peridotite and eclogite coexisting with reduced C-O-H fluid have been studied at 3-16 GPa and 1200-1600 °C. In order to perform these experiments the double-capsule technique with fO2 control by outer Mo-MoO2 or Fe-FeO buffer capsule was designed and developed for multianvil experiments at pressures 3-21 GPa. Silicate phase assemblages resemble those in volatile-free lithologies, i.e. olivine/wadsleyite-orthopyroxene-clinopyroxene-garnet in peridotite and garnet-omphacite in eclogite. Melting was detected by the appearance of quenched crystals of pyroxene, feldspar and glassy silica. Estimated solidus temperatures for peridotite + C-O-H fluid with fO2=Fe-FeO are 1200 °C at 3 GPa and 1700 °C at 16 GPa. The solidus of the system with fO2=Mo-MoO2 was about 100 °C lower. Estimated solidus temperatures for eclogite + C-O-H fluid with fO2=Fe-FeO are 1100 °C at 3 GPa and 1600 °C at 16 GPa, and for eclogite at fO2=Mo-MoO2 solidus temperatures were 20-50 °C lower. These solidus temperatures are much higher (300-500 °C) than those for peridotite and eclogite systems with H2O and/or CO2, but are still 300-400 °C lower than the solidi of volatile-free peridotite and eclogite at studied pressures. The compositions of partial melt were estimated from mass-balance calculations: partial melts of peridotite have CaO-poor (6-9 wt.%) basaltic compositions with 44-47 wt.% SiO2 and 1.1-1.6 wt.% Na2O. Melts of eclogite contain more SiO2 (47-49 wt.%) and are enriched in CaO (9-15 wt.%), Na2O (9-14 wt.%), and K2O (1.3-2.2 wt.%). All runs contained graphite or diamond crystals along with porous carbon aggregate with micro-inclusions of silicates indicating that reduced fluid may dissolve significant amounts of silicate components. Analyses of carbon aggregates using a defocused electron microprobe beam reveal compositions similar to estimated partial melts. The diamonds formed from reduced C-O-H fluid may have natural analogues as polycrystalline diamonds. The oxygen fugacity in the Earth's mantle decreases with pressure from about fayalite-magnetite-quartz at shallow depths of 20-50 km to about iron-wustite at 250-300 km according to fO2 estimations from cratonic peridotite. We show significant increase of solidus temperatures in peridotite and eclogite coexisting with reduced CH4-H2O fluid relative to the systems with oxidized H2O-CO2 fluid. We emphasize that redox melting by change of oxidation state across a mantle section, a phase transition, or the lithosphere-asthenosphere boundary can be the dominant melting process in the deep Earth's interior.

Litasov, Konstantin D.; Shatskiy, Anton; Ohtani, Eiji

2014-04-01

390

Geochemistry of black shales from the Lower Cretaceous Paja Formation, Eastern Cordillera, Colombia: Source weathering, provenance, and tectonic setting  

NASA Astrophysics Data System (ADS)

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.

Campos Alvarez, N. O.; Roser, B. P.

2007-04-01

391

Compositional data for twenty-one Fra Mauro lunar materials.  

NASA Technical Reports Server (NTRS)

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.

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

392

New data on selected Ivory Coast tektites.  

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

393

[Studies on the hygiene of arc-welding. (Part 8). Effects of atmospheric conditions on the chemical composition of fumes from low hydrogen welding].  

PubMed

Welding fumes were generated from several kinds of low hydrogen type electrodes which changed the atmosphere with use of various gases, such air, Ar, CO2 and N2, and were collected in water with an impinger. These fumes were analyzed by X-ray refractometry and chemical analysis, and pH of their collecting water was measured. Based on these results, this paper discusses the mechanism of scattering K and Na in fumes from low hydrogen welding which are considered to be the sources of respiratory tract irritation. All sample fumes from low hydrogen welding in several atmospheric conditions contained fluorite (CaF2). The pH of water in which all sample fumes were collected remarkably elevated. Chemical composition ratios of both K2O and Na2O in all sample fumes were larger than those in coating materials. The sample fumes from welding in each of both N2 and CO2 atmosphere showed higher ratios of K2O and Na2O than those in Ar. The conclusions obtained from the discussion are as follows: The potential gradient of the arc becomes larger during welding in the atmosphere with use of N2 or CO2 because the dissociation voltage of N2 and CO2 is very low. Furthermore, fluorite (CaF2) makes the slag more fluid. Then, K and Na become easily dispersed from the arc column of low hydrogen welding. PMID:3773298

Mori, T; Akashi, S; Takeoka, K; Yoshinaka, M

1986-05-01

394

Calcium-sodium antagonism on the frog's heart: a voltage-clamp study.  

PubMed Central

1. In double sucrose-gap voltage-clamped frog atrial fibres the influence of [Ca]o and [Na]o on membrane current and contraction was investigated. 2. The slow (secondary) inward current varied with [Ca]o but was almost insensitive to changes in [Na]o. In contrast, the phasic (transient) contraction initiated by the slow inward current was affected by both [Ca]o and [Na]o. 3. With moderate changes of [Ca]o and [Na]o from normal, the strength of phasic contraction at a given depolarization followed the [Ca]o/[Na]2o ratio approximately. This was best seen at membrane potentials near zero level. 4. Under the same conditions, tonic (sustained) contractions associated with prolonged depolarizations were strictly correlated to the [Ca]o/[Na]2o ratio at any potential. No interrelation between tonic tension and steady-state current was found. 5. With extensive changes in [Ca]o and [Na]o, the sensitivity of both phasic and tonic tension to the [Ca]o/[Na]2o ratio declined, the negative effect of [Na]o becoming smaller than was expected from this ratio. 6. In Na-free choline-Ringer, a strong contracture developed followed by a spontaneous relaxation. Starting from the relaxed state, application of depolarizing clamps gave rise to phasic contractions with a very slow relaxation while tonic contractions were apparently lacking. 7. The results are interpreted in terms of an energy-dependent carrier mechanism exchanging one Ca for two Na ions across the cell membrane. The model implies a strong asymmetry in the rate constants governing the chemical reactions on both sides of the membrane. The system is thought to operate close to equilibrium at any potential, thereby determining the steady level of myoplasmic Ca. The equilibrium itself is considered to shift upon depolarization. Assuming that [Na]i is constant, the steady level of [Ca]i is expected to be proportional to the [Ca]o/[Na]2o ratio, the scale factor being a function of membrane potential. 8. The carrier model suggests the occurrence of a depolarization-induced inward transfer of Ca which might be involved in the generation of tonic contractions. 9. The apparent lack of tonic contractions in the absence of external Na ions may be explained by a suppression of carrier-mediated Ca influx normally occurring upon depolarization. 10. The antagonistic effects of [Ca]o and [Na]o on phasic contraction are understood as being due to alterations of the Ca pumping system rather than changes in slow inward current. PMID:957260

Benninger, C; Einwächter, H M; Haas, H G; Kern, R

1976-01-01

395

Late Paleozoic granitoid magmatism in Chukotka and its relation to Ellesmerian orogeny in Arctic Alaska and Canada  

NASA Astrophysics Data System (ADS)

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 M