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Sample records for al ca cd

  1. White LED based on CaAl2Si2O8:Eu2+ Mn2+ phosphor and CdS/ZnS quantum dots

    NASA Astrophysics Data System (ADS)

    Shen, Changyu; Zhong, Chuan; Hou, Qianglong; Li, Ke

    2011-02-01

    Core/shell CdS/ZnS quantum dots (QDs) with the emission wavelength of 610nm, was synthesized by thermal deposition using cadmium oxide and selenium as precursors in a hot lauric acid and hexadecylamine trioctylphosphine oxide hybrid. CaAl2Si2O8:Eu2+ Mn2+ phosphor was synthesized by high-temperature solid state reaction at 1290 °C for 2 hours under the H2 reducing atmosphere, and X-ray powder diffraction analysis confirmed the formation of it. It has two emission bands peaking at 420 nm and 580nm originated from the transition 5d to 4f of Eu2+ and 4T1-6A1 of Mn2+, respectively. Blends of CaAl2Si2O8:Eu2+,Mn2+ phosphor and CdS/ZnS QDs exhibited the prominent spectral evolution with an increasing content of QDs. A hybrid white LED, which combines a blue LED with the blend of CaAl2Si2O8:Eu2+ Mn2+ phosphor and QDs with a weight ratio of 2:1, with the CIE coordinate of (0.3183, 0.3036) and CRI of 85 was obtained.

  2. Effects of Cd and Al stress on secondary metabolites, antioxidant and antibacterial activity of Hypoxis hemerocallidea Fisch. & C.A. Mey.

    PubMed

    Okem, Ambrose; Stirk, Wendy A; Street, Renée A; Southway, Colin; Finnie, Jeffrey F; Van Staden, Johannes

    2015-12-01

    This study investigated the effects of cadmium (Cd) and aluminium (Al) on the accumulation of phenolics, flavonoids and the bioactive compound hypoxoside in Hypoxis hemerocallidea. In addition, antioxidant scavenging and antibacterial activity were assessed to evaluate if Cd and Al stress affect the accumulation of bioactive compounds in H. hemerocallidea. In vitro grown plantlets of H. hemerocallidea were acclimatized for seven months in a greenhouse. Thereafter plants were exposed to various concentrations of Cd and Al both singularly and in combination in the form of Cd(NO3)2 (2, 5, 10 mg Cd/L); Al3(NO3)3 (500, 1000, 1500 mg Al/L) and combinations of Cd and Al (Cd 2:Al 500, Cd 5:Al 1000 and Cd 10:Al 1500 mg/L) for a further six weeks. The highest amounts of Cd and Al translocated to the shoot were 34 and 1608 mg/L respectively. Phytochemical screening showed significantly high amounts of total phenolics and flavonoids at the moderate Cd treatment (5 mg/L) compared to the controls. Exposure to Cd and Al significantly decreased the accumulation of hypoxoside. There was a significant increase in diphenylpicrylhydrazyl (DPPH) antioxidant scavenging activity in most of the metal-treated plants compared to the positive control ascorbic acid. Extracts from Cd 2 mg/L treatment exhibited moderate antibacterial activity against Staphylococcus aureus compared to the control. The results of the present study revealed that cultivating H. hemerocallidea on metal contaminated soils affects the accumulation of the bioactive compound, hypoxoside.

  3. High-Temperature Vaporization Behavior of Oxides II. Oxides of Be, Mg, Ca, Sr, Ba, B, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Zn, Cd, and Hg

    NASA Astrophysics Data System (ADS)

    Lamoreaux, R. H.; Hildenbrand, D. L.; Brewer, L.

    1987-07-01

    In order to assess the high-temperature vaporization behavior and equilibrium gas phase compositions over the condensed oxides of Be, Mg, Ca, Sr, Ba, B, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Zn, Cd, and Hg, the relevant thermodynamic and molecular constant data have been compiled and critically evaluated. Selected values of the Gibbs energy functions of condensed and vapor phases are given in the form of equations valid over wide temperature ranges, along with the standard entropies and enthalpies of formation. These data were used to generate plots of equilibrium partial pressures of vapor species as functions of temperature for representative environmental conditions ranging from reducing to oxidizing. The calculated partial pressures and compositions agree, for the most part, with experimental results obtained under comparable conditions. Maximum vaporization rates have been calculated using the Hertz-Knudsen equation. Literature references are given.

  4. (Sr1-xNax)(Cd1-xMnx)2As2: A new charge and spin doping decoupled diluted magnetic semiconductors with CaAl2Si2-type structure

    NASA Astrophysics Data System (ADS)

    Chen, Bijuan; Deng, Zheng; Li, Wenmin; Gao, Moran; Li, Zhi; Zhao, Guoqiang; Yu, Shuang; Wang, Xiancheng; Liu, Qingqing; Jin, Changqing

    2016-08-01

    We report the synthesis and characterization of a new bulk diluted ferromagnetic semiconductor via Na and Mn co-doping in SrCd2As2 with a hexagonal CaAl2Si2-type structure. Together with carrier doping via (Sr,Na) substitution, spin doping via (Cd,Mn) substitution results in ferromagnetic order with Curie temperature of TC up to 13 K. Negative magnetoresistance is assigned to weak localization at low temperatures, where the magnetization of samples becomes saturated. The hexagonal structure of (Sr1-xNax)(Cd1-xMnx)2As2 can be acted as a promising candidate for spin manipulations owing to its relatively small coercive field of less than 24 Oe.

  5. Observations of Al, Fe and Ca(+) in Mercury's Exosphere

    NASA Technical Reports Server (NTRS)

    Bida, Thomas A.; Killen, Rosemary M.

    2011-01-01

    We report 5-(sigma) tangent column detections of Al and Fe, and strict 3-(sigma) tangent column upper limits for Ca(+) in Mercury's exosphere obtained using the HIRES spectrometer on the Keck I telescope. These are the first direct detections of Al and Fe in Mercury's exosphere. Our Ca(-) observation is consistent with that reported by The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft.

  6. The role of Ca pathway in Cd uptake and translocation by the hyperaccumulator Sedum alfredii.

    PubMed

    Lu, Lingli; Tian, Shengke; Zhang, Min; Zhang, Jie; Yang, Xiaoe; Jiang, Hong

    2010-11-15

    Effect of Ca on plant growth, Cd uptake and translocation in the hyperaccumulator Sedum alfredii was investigated, as to reveal the possible pathway of Cd entry into the plants system. High Ca increased plant growth under Cd stress after 7 d, and significantly affected the total Cd influx and translocation rate. Short-term kinetics of (109)Cd influx performed using radiotracers confirmed a significant inhibition of (109)Cd influx into the roots induced by high Ca. Under exposure of 5.0 mM Ca, K(m) of (109)Cd influx into roots was 2-fold higher in the hyperaccumulator, although the V(max) value remained at similar level, when compared with the treatments of 0.5 mM Ca. Calcium concentrations in xylem sap of the hyperaccumulator decreased with the increasing Cd levels and significant negative correlationship between the two elements was observed. However, increased xylem loading of Cd was observed in the hyperaccumulator in response to the increasing exogenous Ca level from 0.5 to 4.0 mM, but reverse effect was observed when higher Ca levels (8-32 mM) were presented in the solutions. These results suggest that Cd uptake and translocation in the hyperaccumulator S. alfredii plants is positively associated with Ca pathway. PMID:20674155

  7. CD36 Protein Influences Myocardial Ca2+ Homeostasis and Phospholipid Metabolism

    PubMed Central

    Pietka, Terri A.; Sulkin, Matthew S.; Kuda, Ondrej; Wang, Wei; Zhou, Dequan; Yamada, Kathryn A.; Yang, Kui; Su, Xiong; Gross, Richard W.; Nerbonne, Jeanne M.; Efimov, Igor R.; Abumrad, Nada A.

    2012-01-01

    Sarcolemmal CD36 facilitates myocardial fatty acid (FA) uptake, which is markedly reduced in CD36-deficient rodents and humans. CD36 also mediates signal transduction events involving a number of cellular pathways. In taste cells and macrophages, CD36 signaling was recently shown to regulate store-responsive Ca2+ flux and activation of Ca2+-dependent phospholipases A2 that cycle polyunsaturated FA into phospholipids. It is unknown whether CD36 deficiency influences myocardial Ca2+ handling and phospholipid metabolism, which could compromise the heart, typically during stresses. Myocardial function was examined in fed or fasted (18–22 h) CD36−/− and WT mice. Echocardiography and telemetry identified conduction anomalies that were associated with the incidence of sudden death in fasted CD36−/− mice. No anomalies or death occurred in WT mice during fasting. Optical imaging of perfused hearts from fasted CD36−/− mice documented prolongation of Ca2+ transients. Consistent with this, knockdown of CD36 in cardiomyocytes delayed clearance of cytosolic Ca2+. Hearts of CD36−/− mice (fed or fasted) had 3-fold higher SERCA2a and 40% lower phospholamban levels. Phospholamban phosphorylation by protein kinase A (PKA) was enhanced after fasting reflecting increased PKA activity and cAMP levels in CD36−/− hearts. Abnormal Ca2+ homeostasis in the CD36−/− myocardium associated with increased lysophospholipid content and a higher proportion of 22:6 FA in phospholipids suggests altered phospholipase A2 activity and changes in membrane dynamics. The data support the role of CD36 in coordinating Ca2+ homeostasis and lipid metabolism and the importance of this role during myocardial adaptation to fasting. Potential relevance of the findings to CD36-deficient humans would need to be determined. PMID:23019328

  8. Coral Cd/Ca and Mn/Ca records of ENSO variability in the Gulf of California

    NASA Astrophysics Data System (ADS)

    Carriquiry, J. D.; Villaescusa, J. A.

    2010-06-01

    We analyzed the trace element ratios Cd/Ca and Mn/Ca in three coral colonies (Porites panamensis (1967-1989), Pavona clivosa (1967-1989) and Pavona gigantea (1979-1989)) from Cabo Pulmo reef, Southern Gulf of California, Mexico, to assess the oceanographic changes caused by El Niño - Southern Oscillation (ENSO) events in the Eastern Tropical North Pacific (ETNP). Interannual variations in the coral Cd/Ca and Mn/Ca ratios showed clear evidence that incorporation of Cd and Mn in the coral skeleton was influenced by ENSO conditions, but the response for each metal was controlled by different processes. The Mn/Ca ratios were significantly higher during ENSO years (p<0.05) relative to non-ENSO years for the three species of coral. In contrast, the Cd/Ca was systematically lower during ENSO years, but the difference was significant (p<0.05) only in Pavona gigantea. A decrease in the incorporation of Cd and a marked increase in Mn indicated strongly reduced vertical mixing in the Gulf of California during the mature phase of El Niño. The oceanic warming during El Niño events produces a relaxation of upwelling and a stabilization of the thermocline, which may act as a physical barrier limiting the transport of Cd from deeper waters into the surface layer. In turn, this oceanic condition can increase the residence time of particulate-Mn in surface waters, allowing an increase in the photo-reduction of particulate-Mn and the release of available Mn into the dissolved phase. These results support the use of Mn/Ca and Cd/Ca ratios in biogenic carbonates as tracers of increases in ocean stratification and trade wind weakening and/or collapse in the ETNP during ENSO episodes.

  9. Evaluation of liquid metal embrittlement of SS304 by Cd and Cd-Al solutions

    SciTech Connect

    Thomas, J.K.; Iyer, N.C.; Begley, J.A.

    1992-07-01

    The susceptibility of stainless steel 304 to liquid metal embrittlement (LME) by cadmium (Cd) and cadmium-aluminum (Cd-Al) solutions was examined as part of a failure evaluation for SS304-clad cadmium reactor safety rods which had been exposed to elevated temperatures. The active, or cadmium (Cd) bearing, portion of the safety rod consists of a 0.756 in. diameter aluminum allow (Al-6061) core, a 0.05 in. thick Cd layer, and a 0.042 in. thick Type 304 stainless steel cladding. The safety rod thermal tests were conducted as part of a program to define the response of reactor core components to a hypothetical LOCA for the Savannah River Site (SRS) production reactor. LME was considered as a potential failure mechanism based on the nature of the failure and susceptibility of austenitic stainless steels to embrittlement by other liquid metals.

  10. Evaluation of liquid metal embrittlement of SS304 by Cd and Cd-Al solutions

    SciTech Connect

    Thomas, J.K.; Iyer, N.C. ); Begley, J.A. )

    1992-01-01

    The susceptibility of stainless steel 304 to liquid metal embrittlement (LME) by cadmium (Cd) and cadmium-aluminum (Cd-Al) solutions was examined as part of a failure evaluation for SS304-clad cadmium reactor safety rods which had been exposed to elevated temperatures. The active, or cadmium (Cd) bearing, portion of the safety rod consists of a 0.756 in. diameter aluminum allow (Al-6061) core, a 0.05 in. thick Cd layer, and a 0.042 in. thick Type 304 stainless steel cladding. The safety rod thermal tests were conducted as part of a program to define the response of reactor core components to a hypothetical LOCA for the Savannah River Site (SRS) production reactor. LME was considered as a potential failure mechanism based on the nature of the failure and susceptibility of austenitic stainless steels to embrittlement by other liquid metals.

  11. Al-Ca and Al-Fe metal-metal composite strength, conductivity, and microstructure relationships

    SciTech Connect

    Kim, Hyong June

    2011-01-01

    Deformation processed metal-metal composites (DMMC’s) are composites formed by mechanical working (i.e., rolling, swaging, or wire drawing) of two-phase, ductile metal mixtures. Since both the matrix and reinforcing phase are ductile metals, the composites can be heavily deformed to reduce the thickness and spacing of the two phases. Recent studies have shown that heavily drawn DMMCs can achieve anomalously high strength and outstanding combinations of strength and conductivity. In this study, Al-Fe wire composite with 0.07, 0.1, and 0.2 volume fractions of Fe filaments and Al-Ca wire composite with 0.03, 0.06, and 0.09 volume fractions of Ca filaments were produced in situ, and their mechanical properties were measured as a function of deformation true strain. The Al-Fe composites displayed limited deformation of the Fe phase even at high true strains, resulting in little strengthening effect in those composites. Al-9vol%Ca wire was deformed to a deformation true strain of 13.76. The resulting Ca second-phase filaments were deformed to thicknesses on the order of one micrometer. The ultimate tensile strength increased exponentially with increasing deformation true strain, reaching a value of 197 MPa at a true strain of 13.76. This value is 2.5 times higher than the value predicted by the rule of mixtures. A quantitative relationship between UTS and deformation true strain was determined. X-ray diffraction data on transformation of Al + Ca microstructures to Al + various Al-Ca intermetallic compounds were obtained at the Advanced Photon Source at Argonne National Laboratory. Electrical conductivity was measured over a range of true strains and post-deformation heat treatment schedules.

  12. Effect of Cd substitution on the optical and transport properties of CaCu_3Ti_4O_12 boldmath

    NASA Astrophysics Data System (ADS)

    Homes, C. C.; Vogt, T.; Subramanian, M. A.; Ramirez, A. P.

    2003-03-01

    The effect of Cd doping on the transport and optical properties of CaCu_3Ti_4O_12 has been studied. At room temperature, CaCu_3Ti_4O_12 has a very high dielectric constant, \\varepsilon_0 ˜ 10^4. However, substituting Cd for Ca reduces \\varepsilon0 by nearly two orders of magnitude. Cd has a strong effect on the low frequency infrared active modes, and in addition a new mode is activated. A normal coordinate analysis has been performed to determine the nature of the vibrational modes, in particular the activated mode as well as the low frequency vibration, where an anomalous increase in the oscillator strength has been observed.(C.C. Homes et al.), Science 293, 673 (2001). It has been suggested that the large values of \\varepsilon0 may be due to a internal barrier layer capacitance effect due to twinning. The lower value for \\varepsilon0 in the Cd material may have implications for the degree of twinning and the associated changes in vibrational structure. This work was supported by the Department of Energy under contract number DE-AC02-98CH10886.

  13. LiCaAl/sub 6/:Cr/sup 3+/

    SciTech Connect

    Payne, S.A.; Chase, L.L.; Newkirk, H.W.; Smith, L.K.; Krupke, W.F. )

    1988-11-01

    The authors report the discovery of a new laser, LiCaAIF/sub 6/:Cr/sup 3/ (Cr/sup 3+/ :LiCAF). The intrinsic (extrapolated maximum) slope efficiency was found to be 67 percent. For comparison, they also measured the intrinsic slope efficiencies of BeAl/sub 2/O/sub 4/:Cr/sup 3+/ (alexandrite), Na/sub 3/Ga/sub 2/Li/sub 3/F/sub 12/:Cr/sup 3+/, and ScBO/sub 3/:Cr/sup 3+/, and obtained values of 65,28, and 26 percent, respectively. The tuning range of LiCaAIF/sub 6/:Cr/sup 3+/ was determined to be at least 720-840 nm. The conventional spectroscopic properties, such as the absorption, emission, and emission lifetimes as a function of temperature, are reported as well.

  14. Cluster Chemistry in Electron-Poor Ae-Pt-Cd Systems (Ae=Ca, Sr, Ba): (Sr,Ba)Pt2Cd4, Ca6Pt8Cd16, and Its Known Antitype Er6Pd16Sb8

    SciTech Connect

    Samal, Saroj L.; Gulo, Fakhili; Corbett, John D.

    2013-02-18

    Three new ternary polar intermetallic compounds, cubic Ca6Pt8Cd16, and tetragonal (Sr, Ba)Pt2Cd4 have been discovered during explorations of the Ae–Pt–Cd systems. Cubic Ca6Pt8Cd16 (Fm-3m, Z = 4, a = 13.513(1) Å) contains a 3D array of separate Cd8 tetrahedral stars (TS) that are both face capped along the axes and diagonally bridged by Pt atoms to generate the 3D anionic network Cd8[Pt(1)]6/2[Pt(2)]4/8. The complementary cationic surface of the cell consists of a face-centered cube of Pt(3)@Ca6 octahedra. This structure is an ordered ternary variant of Sc11Ir4 (Sc6Ir8Sc16), a stuffed version of the close relative Na6Au7Cd16, and a network inverse of the recent Er6Sb8Pd16 (compare Ca6Pt8Cd16). The three groups of elements each occur in only one structural version. The new AePt2Cd4, Ae = Sr, Ba, are tetragonal (P42/mnm,Z = 2, a ≈ 8.30 Å, c ≈ 4.47 Å) and contain chains of edge-sharing Cd4 tetrahedra along c that are bridged by four-bonded Ba/Sr. LMTO-ASA and ICOHP calculation results and comparisons show that the major bonding (Hamilton) populations in Ca6Pt8Cd16 and Er6Sb8Pd16 come from polar Pt–Cd and Pd–Sb interactions, that Pt exhibits larger relativistic contributions than Pd, that characteristic size and orbital differences are most evident for Sb 5s, Pt8, and Pd16, and that some terms remain incomparable, Ca–Cd versus Er–Pd.

  15. CD38-mediated Ca(2+) signaling contributes to glucagon-induced hepatic gluconeogenesis.

    PubMed

    Rah, So-Young; Kim, Uh-Hyun

    2015-06-03

    CD38 is a multifunctional enzyme for the synthesis of Ca(2+) second messengers. Glucagon promotes hepatic glucose production through Ca(2+) signaling in the fasting condition. In this study, we investigated the role of CD38 in the glucagon signaling of hepatocytes. Here, we show that glucagon induces cyclic ADP-ribose (cADPR) production and sustained Ca(2+) increases via CD38 in hepatocytes. 8-Br-cADPR, an antagonistic cADPR analog, completely blocked glucagon-induced Ca(2+) increases and phosphorylation of cAMP response element-binding protein (CREB). Moreover, glucagon-induced sustained Ca(2+) signals and translocation of CREB-regulated transcription coactivator 2 to the nucleus were absent and glucagon-induced glucose production and expression of glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (Pck1) are remarkably reduced in hepatocytes from CD38(-/-) mice. Furthermore, in the fasting condition, CD38(-/-) mice have decreased blood glucose and hepatic expression of G6Pase and Pck1 compared to wild type mice. Our data suggest that CD38/cADPR-mediated Ca(2+) signals play a key role in glucagon-induced gluconeogenesis in hepatocytes, and that the signal pathway has significant clinical implications in metabolic diseases, including type 2 diabetes.

  16. CD38-mediated Ca2+ signaling contributes to glucagon-induced hepatic gluconeogenesis

    PubMed Central

    Rah, So-Young; Kim, Uh-Hyun

    2015-01-01

    CD38 is a multifunctional enzyme for the synthesis of Ca2+ second messengers. Glucagon promotes hepatic glucose production through Ca2+ signaling in the fasting condition. In this study, we investigated the role of CD38 in the glucagon signaling of hepatocytes. Here, we show that glucagon induces cyclic ADP-ribose (cADPR) production and sustained Ca2+ increases via CD38 in hepatocytes. 8-Br-cADPR, an antagonistic cADPR analog, completely blocked glucagon-induced Ca2+ increases and phosphorylation of cAMP response element-binding protein (CREB). Moreover, glucagon-induced sustained Ca2+ signals and translocation of CREB-regulated transcription coactivator 2 to the nucleus were absent and glucagon-induced glucose production and expression of glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (Pck1) are remarkably reduced in hepatocytes from CD38−/− mice. Furthermore, in the fasting condition, CD38−/− mice have decreased blood glucose and hepatic expression of G6Pase and Pck1 compared to wild type mice. Our data suggest that CD38/cADPR-mediated Ca2+ signals play a key role in glucagon-induced gluconeogenesis in hepatocytes, and that the signal pathway has significant clinical implications in metabolic diseases, including type 2 diabetes. PMID:26038839

  17. Effect of reaction time and (Ca+Mg)/Al molar ratios on crystallinity of Ca-Mg-Al layered double Hydroxide

    NASA Astrophysics Data System (ADS)

    Heraldy, E.; Nugrahaningtyas, K. D.; Sanjaya, F. B.; Darojat, A. A.; Handayani, D. S.; Hidayat, Y.

    2016-02-01

    Ca-Mg-Al Layered Double Hydroxides (Ca-Mg-Al-LDH) compounds were successfully synthesized from brine water and AlCl3.6H2O as the starting materials by coprecipitation method. The product result was characterized by X-ray powder diffraction (XRD) and Fourier transform infrared (FT-IR). The effects of the reaction time and the molar ratios of the raw material on the crystallinity of Ca-Mg-Al-LDH were examining. Results show that increasing reaction time (30; 60 and 90 min.) could improve the crystallinity and monodispersity of layered double hydroxide compounds particles. The well-defined Ca-Mg- Al-LDH could be prepared with (Ca+Mg)/Al molar ratios 0.5.

  18. Sodium chloride salinity reduces Cd uptake by edible amaranth (Amaranthus mangostanus L.) via competition for Ca channels.

    PubMed

    Mei, XiuQin; Li, SongSong; Li, QuSheng; Yang, YuFeng; Luo, Xuan; He, BaoYan; Li, Hui; Xu, ZhiMin

    2014-07-01

    Soil salinity is known to enhance cadmium (Cd) accumulation in crops. However, the mechanism by which this occurs independent of the surrounding soil remains unclear. In this study, root adsorption and uptake of salt cations and Cd by edible amaranth under NaCl salinity stress were investigated in hydroponic cultures with 0, 40, 80, 120, and 160mM of NaCl and 27nM Cd. The dominant Cd species in the nutrient solution changed from free Cd(2+) to Cd chlorocomplexes as NaCl salinity increased. High salinity significantly reduced K, Ca, and Cd root adsorption and K, Ca, Mg, and Cd uptake. High salinity decreased root adsorption of Cd by 43 and 58 percent and Cd uptake by 32 and 36 percent in salt-tolerant and salt-sensitive cultivars, respectively. Transformation of Cd from free ion to chlorocomplexes is unlikely to have significantly affected Cd uptake by the plant because of the very low Cd concentrations involved. Application of Ca ion channel blocker significantly reduced Na, K, Ca, Mg, and Cd uptake by the roots, while blocking K ion channels significantly reduced Na and K uptake but not Ca, Mg, and Cd uptake. These results suggest that Na was absorbed by the roots through both Ca and K ion channels, while Cd was absorbed by the roots mainly through Ca ion channels and not K ion channels. Salinity caused a greater degree of reduction in Cd adsorption and uptake in the salt-sensitive cultivar than in the salt-tolerant cultivar. Thus, competition between Na and Cd for Ca ion channels can reduce Cd uptake at very low Cd concentrations in the nutrient solution.

  19. Sodium chloride salinity reduces Cd uptake by edible amaranth (Amaranthus mangostanus L.) via competition for Ca channels.

    PubMed

    Mei, XiuQin; Li, SongSong; Li, QuSheng; Yang, YuFeng; Luo, Xuan; He, BaoYan; Li, Hui; Xu, ZhiMin

    2014-07-01

    Soil salinity is known to enhance cadmium (Cd) accumulation in crops. However, the mechanism by which this occurs independent of the surrounding soil remains unclear. In this study, root adsorption and uptake of salt cations and Cd by edible amaranth under NaCl salinity stress were investigated in hydroponic cultures with 0, 40, 80, 120, and 160mM of NaCl and 27nM Cd. The dominant Cd species in the nutrient solution changed from free Cd(2+) to Cd chlorocomplexes as NaCl salinity increased. High salinity significantly reduced K, Ca, and Cd root adsorption and K, Ca, Mg, and Cd uptake. High salinity decreased root adsorption of Cd by 43 and 58 percent and Cd uptake by 32 and 36 percent in salt-tolerant and salt-sensitive cultivars, respectively. Transformation of Cd from free ion to chlorocomplexes is unlikely to have significantly affected Cd uptake by the plant because of the very low Cd concentrations involved. Application of Ca ion channel blocker significantly reduced Na, K, Ca, Mg, and Cd uptake by the roots, while blocking K ion channels significantly reduced Na and K uptake but not Ca, Mg, and Cd uptake. These results suggest that Na was absorbed by the roots through both Ca and K ion channels, while Cd was absorbed by the roots mainly through Ca ion channels and not K ion channels. Salinity caused a greater degree of reduction in Cd adsorption and uptake in the salt-sensitive cultivar than in the salt-tolerant cultivar. Thus, competition between Na and Cd for Ca ion channels can reduce Cd uptake at very low Cd concentrations in the nutrient solution. PMID:24785711

  20. Substantial Cd-Cd Bonding in Ca6PtCd11: A Condensed Intermetallic Phase Built of Pentagonal Cd7 and Rectangular Cd4/2Pt Pyramids

    SciTech Connect

    Gulo, Fakhili; Samal, Saroj L.; Corbett, John D.

    2013-08-19

    The new trail-breaking compound Ca6PtCd11 has been synthesized and its structural and bonding properties investigated. This unusual phase features an unprecedented degree of cadmium aggregation, including linear chains, novel Cd7 PBP aggregates, and edge-shared chains of PtCd4/2 square pyramids. Manifestations of this chemistry elsewhere has evidently been precluded in earlier work by the inclusion of larger amounts of the strong d-metal bonding Au or Pt. Under the right conditions Cd seems quite effective as an open s,p-band metal.

  1. Estimation Model for Electrical Conductivity of CaF2-CaO-Al2O3 Slags

    NASA Astrophysics Data System (ADS)

    Shi, Guan-yong; Zhang, Ting-an; Dou, Zhi-he; Niu, Li-ping

    2016-09-01

    Electrical conductivity is one of the most important properties of molten slags. It has an important influence on process parameter selection of the electroslag remelting process. In the present work, a new model for estimating electrical conductivity of high-temperature slags has been proposed via calculating the conductivity by electrical conductivity of pure substances and interaction parameters between the different components in the slag has been proposed. In this model, the Arrhenius law is used to describe the relationship between electrical conductivity and temperature of slags. This model has been successfully applied to the CaF2-Al2O3, CaF2-CaO, and CaO-Al2O3, as well as CaF2-CaO-Al2O3 systems, and the calculated results are in good agreement with the measured values.

  2. Actinide chemistry in Allende Ca-Al-rich inclusions

    NASA Technical Reports Server (NTRS)

    Murrell, M. T.; Burnett, D. S.

    1987-01-01

    Fission track radiography is used to investigate the U and Th microscale distribution in a set of Allende-meteorite Ca-Al-rich inclusions. In the Type B inclusions, the major phases melilite and fassaite are important actinide host phases, and on the rims of Type B inclusions and throughout all other inclusions studied, perovskite is the dominant actinide host phase. Results suggest that neither alteration nor loss or gain of an actinide-rich phase appears to have been an important Th/U fractionation mechanism, and that volatility differences may be the dominant factor. Th/U and rare earth element abundance patterns for the spinel and perovskite rim suggest rim formation by volatilization of interior material, and within the constraints of the brief time scale required for this heating, several mechanisms for spinel-perovskite rim formation are possible.

  3. Tululite, Ca14(Fe3+,Al)(Al,Zn,Fe3+,Si,P,Mn,Mg)15O36: a new Ca zincate-aluminate from combustion metamorphic marbles, central Jordan

    NASA Astrophysics Data System (ADS)

    Khoury, Hani N.; Sokol, Ella V.; Kokh, Svetlana N.; Seryotkin, Yurii V.; Nigmatulina, Elena N.; Goryainov, Sergei V.; Belogub, Elena V.; Clark, Ian D.

    2016-02-01

    Tululite (Ca14(Fe3+,Al)(Al,Zn,Fe3+,Si,P,Mn,Mg)15O36 (the hypothetical end-member formula Ca14{Fe3+O6}[SiO4][Zn5Al9]O26) (IMA2014-065) is a new natural Ca zincate-aluminate, identified in medium-temperature (800-850 °C) combustion metamorphic (CM) spurrite-fluorellestadite marbles from central Jordan. The type locality (Tulul Al Hammam area) is situated in the northern part of the Siwaqa complex, the largest area of the "Mottled Zone" Formation in the Dead Sea region. The marbles originated from bitumen-rich chalky marine sediments of the Maastrichtian-Paleogene Muwaqqar Chalk Marl Formation, which have low clay content (and, consequently, low Al) and high Zn, Cd, and U enrichments. The bulk CM rocks derived from the low-Al protolith have unusually high (Zn + Cd)/Al ratios ( 0.2) and, as a result, a mineralogy with negligibly small percentages of Ca aluminates having low Ca:Al molar ratios (minerals of mayenite supergroup, Ca:Al = 6:7) common to most of calcareous CM rocks in the Mottled Zone. Instead, the mineral assemblage of the Zn-rich marbles contains tululite, with high Ca:Al = 2.55 molar ratios and Zn substituting for a large portion of Al (Zn:Al = 1.1). Tululite occurs in thin clusters as irregular grains with indented outlines (20-100 μm in size), having typical open-work textures associated with rock-forming calcite, fluorellestadite, spurrite, and accessory Zn-rich periclase, lime-monteponite solid solutions, calcium uranates, and zincite. Marbles also bear brownmillerite, dorrite, fluormayenite, high-fluorine Ca aluminate, and lakargiite. Secondary phases are brucite, gel-like calcium silicate hydrates and calcium silicate aluminate hydrates, including Zn- and U-bearing and Cd-rich compounds, Si-bearing hydrated compounds after calcium uranates, and basic Cd chlorides. The empirical formula of the holotype tululite (a mean of 32 analyses) is (Ca13.29Cd0.75)Σ14.04(Al5.46Zn5.20Fe3+ 2.23Si0.95Mn3+ 1.01Mg0.78P0.41)Σ16.04O36. Tululite is cubic, space

  4. Enthalpies of formation of CaAl4O7 and CaAl12O19 (hibonite) by high temperature, alkali borate solution calorimetry

    NASA Technical Reports Server (NTRS)

    Geiger, C. A.; Kleppa, O. J.; Grossman, L.; Mysen, B. O.; Lattimer, J. M.

    1988-01-01

    Enthalpies of formation were determined for two calcium aluminate phases, CaAl4O7 and CaAl12O19, using high-temperature alkali borate solution calorimetry. The aluminates were synthesized by multiple-cycle heating and grinding stoichiometric mixtures of CaCO3 and Al2O3, and the products were characteized by X-ray diffraction and SEM microbeam analysis. The data on impurities (CaAl4O7 was found to be about 89.00 percent pure by weight and the CaAl12O19 samples about 91.48 percent pure) were used to correct the heat of solution values of the synthetic products. The enthalpies of formation, at 1063 K, from oxides, were found to be equal to -(25.6 + or - 4.7) kJ/g.f.w. for CaAl4O7 and -(33.0 + or - 9.7) kJ/g.f.w. for CaAl12O19; the respective standard enthalpies of formation from elements, at 298 K, were estimated to be -4007 + or - 5.2 kJ/g.f.w. and -10,722 + or - 12 kJ/g.f.w.

  5. Synthesis, Structure and bonding Analysis of the Polar Intermetallic Phase Ca2Pt2Cd

    SciTech Connect

    Samal, Saroj L.; Corbett, John D.

    2012-08-14

    The polar intermetallic phase Ca2Pt2Cd was discovered during explorations of the Ca-Pt-Cd system. The compound was synthesized by high temperature reactions, and its structure refined by single-crystal X-ray diffraction as orthorhombic, Immm, a = 4.4514(5), b = 5.8415(6), c = 8.5976(9) Å, Z = 2. The structure formally contains infinite, planar networks of [Pt2Cd]4– along the ab plane, which can be described as tessellation of six and four-member rings of the anions, with cations stuffed between the anion layers. The infinite condensed platinum chains show a substantial long–short distortion of 0.52 Å, an appreciable difference between Ca2Pt2Cd (26 valence electrons) and the isotypic but regular Ca2Cu2Ga (29 VE). The relatively large cation proportion diminishes the usual dominance of polar (Pt–Cd) and 5d–5d (Pt–Pt) contributions to the total Hamilton populations.

  6. Structure, phase composition, and strengthening of cast Al-Ca-Mg-Sc alloys

    NASA Astrophysics Data System (ADS)

    Belov, N. A.; Naumova, E. A.; Bazlova, T. A.; Alekseeva, E. V.

    2016-02-01

    The structure and phase composition of Al-Ca-Mg-Sc alloys containing 0.3 wt % Sc, up to 10 wt % Ca, and up to 10 wt % Mg have been investigated in the cast state and state after heat treatment. It has been shown that only binary phases Al4Ca, Al3Sc, and Al3Mg2 can be in equilibrium with the aluminum solid solution. It has been found that the maximum strengthening effect caused by the precipitation of Al3Sc nanoparticles for all investigated alloys is attained after annealing at 300-350°C.

  7. Ca(2+) and CaM are involved in Al(3+) pretreatment-promoted fluoride accumulation in tea plants (Camellia sinesis L.).

    PubMed

    Zhang, Xian-Chen; Gao, Hong-Jian; Wu, Hong-Hong; Yang, Tian-Yuan; Zhang, Zheng-Zhu; Mao, Jing-Dong; Wan, Xiao-Chun

    2015-11-01

    Tea plant (Camellia sinensis (L.) O. kuntze) is known to be a fluoride (F) and aluminum (Al(3+)) hyper-accumulator. Previous study showed that pre-treatment of Al(3+) caused a significant increase of F accumulation in tea plants. However, less is known about the intricate network of Al(3+) promoted F accumulation in tea plants. In this study, the involvement of endogenous Ca(2+) and CaM in Al(3+) pretreatment-promoted F accumulation in tea plants was investigated. Our results showed that Al(3+) induced the inverse change of intracellular Ca(2+) fluorescence intensity and stimulated Ca(2+) trans-membrane transport in the mature zone of tea root. Also, a link between internal Ca(2+) and CaM was found in tea roots under the presence of Al(3+). In order to investigate whether Ca(2+) and CaM were related to F accumulation promoted by Al(3+) pretreatment, Ca(2+) chelator EGTA and CaM antagonists CPZ and TFP were used. EGTA, CPZ, and TFP pretreatment inhibited Al(3+)-induced increase of Ca(2+) fluorescence intensity and CaM content in tea roots, and also significantly reduced Al(3+)-promoted F accumulation in tea plants. Taken together, our results suggested that the endogenous Ca(2+) and CaM are involved in Al(3+) pretreatment-promoted F accumulation in tea roots. PMID:26318146

  8. Phase Compositions of Self Reinforcement Al2O3/CaAl12O19 Composite using X-ray Diffraction Data and Rietveld Technique

    NASA Astrophysics Data System (ADS)

    Asmi, D.; Low, I. M.; O'Connor, B.

    2008-03-01

    The analysis of x-ray diffraction (XRD) patterns by the Rietveld technique was tested to the quantitatively phase compositions of self reinforcement Al2O3/CaAl12O19 composite. Room-temperature XRD patterns revealed that α-Al2O3 was the only phase presence in the CA0 sample, whereas the α-Al2O3 and CaAl12O19 phases were found for CA5, CA15, CA30, and CA50 samples. The peak intensity of CA6 in the self reinforcement Al2O3/CaAl12O19 composites increased in proportion with increase in CaAl12O19 content in contrast to α-Al2O3. The diffraction patterns for CA100 sample shows minor traces of α-Al2O3 even in relatively low peak intensity. It is suggesting that the in-situ reaction sintering of raw materials were not react completely to form 100 wt% CaAl12O19 at temperature 1650 °C. Quantitative phase compositions of self reinforcement Al2O3/CaAl12O19 composites by Rietveld analysis with XRD data has been well demonstrated. The results showed that the GOF values are relatively low and the fluctuation in the difference plots shows a reasonable fit between the observed and the calculated plot.

  9. Synthesis of Cd/(Al+Fe) layered double hydroxides and characterization of the calcination products

    SciTech Connect

    Perez, M.R.; Barriga, C.; Fernandez, J.M.; Rives, V.; Ulibarri, M.A.

    2007-12-15

    Layered double hydroxides (LDHs) containing Cd(II), Al(III), and Fe(III) in the brucite-like layers with different starting Fe/Al atomic ratios and with nitrate as counteranion have been prepared following the coprecipitation method at a constant pH value of 8. An additional Cd(II),Al(III)-LDH sample interlayered with hexacyanoferrate(III) ions has been prepared by ionic exchange at pH 9. The samples have been characterized by elemental chemical analysis, powder X-ray diffraction (PXRD), and FT-IR spectroscopy. Their thermal stability has been assessed by thermogravimetric and differential thermal analyses (TG-DTA) and mass spectrometric analysis of the evolved gases. The PXRD patterns of the solids calcined at 800 deg. C show diffraction lines corresponding to Cd(Al)O and spinel-type materials, which precise nature (CdAl{sub 2}O{sub 4}, Cd{sub 1-x}Fe{sub 2+x}O{sub 4}, or Cd{sub x}Fe{sub 2.66}O{sub 4}) depends on location and concentration of iron in the parent material or precursor. - Graphical abstract: Layered double hydroxides (LDHs) containing Cd(II), Al(III), and Fe(III) in the brucite-like layers with different starting Fe/Al atomic ratios and with nitrate as counteranion have been prepared following the coprecipitation method. An additional Cd(II),Al(III)-LDH sample interlayered with hexacyanoferrate(III) ions has been prepared by ionic exchange. Calcination at 800 deg. C shows diffraction lines corresponding to CdO and to spinel-type materials. SEM micrograph of sample CdAlFe-N-0.

  10. P- T- X controls on Ca and Na distribution between Mg-Al tourmaline and fluid

    NASA Astrophysics Data System (ADS)

    Berryman, Eleanor J.; Wunder, Bernd; Rhede, Dieter; Schettler, Georg; Franz, Gerhard; Heinrich, Wilhelm

    2016-04-01

    Ca-Na partitioning between tourmaline and a coexisting fluid is investigated in the system CaO-Na2O-B2O3-Al2O3-MgO-SiO2-H2O-Cl between 0.2-4.0 GPa and 500-700 °C. The synthesis experiments produced a mineral assemblage of tourmaline, coesite/quartz, and in some cases additional phases, typically comprising <1 wt% of the solid product. The synthesized tourmalines are solid solutions of dravite [NaMg3Al6Si6O18(BO3)3(OH)3(OH)], "oxy-uvite" (i.e. "Ca-Mg-O root name") [CaMg3Al6Si6O18(BO3)3(OH)3O], and magnesio-foitite [☐(Mg2Al)Al6Si6O18(BO3)3(OH)3(OH)]. Starting materials comprised a fluid of constant ionic strength (2.00 m) and an oxide mixture with a constant Mg/Al ratio. As a result, the number of vacancies at the X site and the Mg/Al ratio of tourmaline crystals synthesized at the same temperature vary only slightly. The major solid solution is Ca-Na exchange at the X site via the exchange vector X Ca W O[ X Na W (OH)]-1, with the exchange vector X (Ca☐)[ X Na2]-1 serving as a secondary Ca-incorporation mechanism. Tourmaline's X-site composition reflects the fluid composition, whereby the Ca (or Na) concentration in the fluid corresponds with the Ca (or Na) content in tourmaline at each pressure and temperature. At 0.2 GPa, 700 °C, Ca preferentially partitions into tourmaline, producing the most Ca-rich tourmaline crystals synthesized here. At pressures >1.0 GPa, Ca partitions preferentially into the fluid, resulting in Na-dominant tourmaline compositions. Temperature has a secondary effect on Ca-Na partitioning, with higher temperatures correlating with increased Ca incorporation in tourmaline. Based on the experimental findings, tourmaline is expected to have Ca-rich compositions when it forms in low pressure, high-temperature Ca-rich rocks, consistent with the current record of tourmaline occurrence. The bulk Mg/Al ratio and the pH of the tourmaline-forming system may also affect Ca incorporation in tourmaline, but remain to be investigated experimentally.

  11. Electrical and optical stimulation of luminescence in Ca 1-xCd xS

    NASA Astrophysics Data System (ADS)

    Viney, I. V. F.; Arterton, B. W.; Ray, B.; Brightwell, J. W.

    1994-04-01

    Mixtures of CaS and CdS treated at 1020°C for 2 h in a nitrogen atmosphere with an excess sulphur pressure have resulted in solid solutions, Ca 1- xCd xS up to x=0.41. Fluorescence emission studies have indicated massively enhanced broad band emission spectra for x between 0.01 and 0.10 at both 77 and 300 K. Electroluminescence studies of copper-coated powder-based samples under AC excitation conditions at x=0.05 have indicated significant emission intensities broadly aligned spectrally with those from photo-stimulation at the same composition. Further investigations are being directed at optimization of composition, particle size, layer thickness and excitation conditions for enhanced electroluminescence emission intensities.

  12. Porous heterometallic Cd(II)-Ca(II)-terephthalate: Synthesis, structure, luminescent and gas adsorption properties

    NASA Astrophysics Data System (ADS)

    Liu, Haiping; Dong, Yanli; Ren, Hailiang

    2016-03-01

    A new heterometallic poly(dihydrate-one and a half terephthalate-cadmium calcium) coordination polymer, namely [CdCa(pdc)1.5(H2O)2]n (1, H2pdc = terephthalic acid), has been successfully obtained by the solvothermal reactions of H2pdc, Cd(NO3)2·4H2O and Ca(NO3)2·4H2O. Single crystal X-ray diffraction analysis reveals that compound 1 features a 3D porous framework based on 1D chain subunits. Moreover, compound 1 is luminescent and exhibits high adsorption capacities for H2, CH4 and CO2 at room temperature.

  13. CaFeAl mixed oxide derived heterogeneous catalysts for transesterification of soybean oil to biodiesel.

    PubMed

    Lu, Yongsheng; Zhang, Zaiwu; Xu, Yunfeng; Liu, Qiang; Qian, Guangren

    2015-08-01

    CaAl layered double oxides (LDO) were prepared by co-precipitation and calcined at 750°C, and then applied to biodiesel production by transesterification reaction between methanol and soybean oil. Compared with characteristics of CaFe/LDO and CaAl/LDO, CaFeAl/LDO had the best performance based on prominent catalytic activity and stability, and achieved over 90% biodiesel yield, which stayed stable (over 85%) even after 8 cycles of reaction. The optimal catalytic reaction condition was 12:1M-ratio of methanol/oil, reaction temperatures of 60°C, 270rpm stirring rate, 60min reaction time, and 6% weight-ratio of catalyst/oil. In addition, the CaFeAl/LDO catalyst is insoluble in both methanol and methyl esters and can be easily separated for further reaction, turning it into an excellent alternative for biodiesel synthesis.

  14. CaFeAl mixed oxide derived heterogeneous catalysts for transesterification of soybean oil to biodiesel.

    PubMed

    Lu, Yongsheng; Zhang, Zaiwu; Xu, Yunfeng; Liu, Qiang; Qian, Guangren

    2015-08-01

    CaAl layered double oxides (LDO) were prepared by co-precipitation and calcined at 750°C, and then applied to biodiesel production by transesterification reaction between methanol and soybean oil. Compared with characteristics of CaFe/LDO and CaAl/LDO, CaFeAl/LDO had the best performance based on prominent catalytic activity and stability, and achieved over 90% biodiesel yield, which stayed stable (over 85%) even after 8 cycles of reaction. The optimal catalytic reaction condition was 12:1M-ratio of methanol/oil, reaction temperatures of 60°C, 270rpm stirring rate, 60min reaction time, and 6% weight-ratio of catalyst/oil. In addition, the CaFeAl/LDO catalyst is insoluble in both methanol and methyl esters and can be easily separated for further reaction, turning it into an excellent alternative for biodiesel synthesis. PMID:25740001

  15. Coral Cd/Ca and Mn/Ca records of El Niño variability in the Gulf of California

    NASA Astrophysics Data System (ADS)

    Carriquiry, J. D.; Villaescusa, J. A.

    2010-02-01

    We analyzed the trace element ratios Cd/Ca and Mn/Ca in three coral colonies (Pavona gigantea, Pavona clivosa and Porites panamensis) from Cabo Pulmo reef, Southern Gulf of California, Mexico, to assess the oceanographic changes caused by El Niño - Southern Oscillation (ENSO) events in the Eastern Tropical North Pacific (ETNP). The interannual variations in the coral Cd/Ca and Mn/Ca ratios show clear evidence that incorporation of Cd and Mn in the coral skeleton are influenced by ENSO conditions, but the response for each metal is controlled by different process. The Mn/Ca ratios were significantly higher during ENSO years (p<0.05) relative to non-ENSO years for the three species of coral. In contrast, the Cd/Ca was systematically lower during ENSO years, but it was significant (p<0.05) only in P. gigantea. The decrease in the incorporation of Cd, and the marked increase in Mn during the mature phase of El Niño indicate strongly reduced vertical mixing in the Gulf of California. The oceanic warming during El Niño events produces a relaxation of upwelling and a stabilization of the thermocline which acts as a physical barrier limiting the transport of Cd from deeper waters into the surface layer. In turn, this oceanic condition can increase the residence time of particulate-Mn in surface waters, which in turn increases the photo-reduction of particulate-Mn and the release of the available Mn into the dissolved phase. These results provide validation for using Mn/Ca and Cd/Ca in biogenic carbonates as tracers of changes in ocean stratification and trade wind weakening and/or collapse in the ETNP during ENSO episodes.

  16. Pressure-induced amorphous-to-amorphous configuration change in Ca-Al metallic glasses

    PubMed Central

    Lou, H. B.; Fang, Y. K.; Zeng, Q. S.; Lu, Y. H.; Wang, X. D.; Cao, Q. P.; Yang, K.; Yu, X. H.; Zheng, L.; Zhao, Y. D.; Chu, W. S.; Hu, T. D.; Wu, Z. Y.; Ahuja, R.; Jiang, J. Z.

    2012-01-01

    Pressure-induced amorphous-to-amorphous configuration changes in Ca-Al metallic glasses (MGs) were studied by performing in-situ room-temperature high-pressure x-ray diffraction up to about 40 GPa. Changes in compressibility at about 18 GPa, 15.5 GPa and 7.5 GPa during compression are detected in Ca80Al20, Ca72.7Al27.3, and Ca66.4Al33.6 MGs, respectively, whereas no clear change has been detected in the Ca50Al50 MG. The transfer of s electrons into d orbitals under pressure, reported for the pressure-induced phase transformations in pure polycrystalline Ca, is suggested to explain the observation of an amorphous-to-amorphous configuration change in this Ca-Al MG system. Results presented here show that the pressure induced amorphous-to-amorphous configuration is not limited to f electron-containing MGs. PMID:22530094

  17. The microstructure-strength relationship in a deformation processed Al-Ca composite

    SciTech Connect

    Tian, Liang; Kim, Hyongjune; Anderson, Iver; Russell, Alan

    2013-02-07

    An Al-9 vol% Ca composite was produced by powder metallurgy and deformation processing. The Al–Ca composite was extruded, swaged and wire drawn to a deformation true strain of 13.8. Both Al and Ca are face-centered cubic, so the Ca second phase deformed into continuous, nearly cylindrical filaments in the Al matrix. The formation of intermetallic compounds, filament coarsening, and spheriodization at elevated temperature was observed by scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction. Both the thickness and spacing of the Ca filaments decreased exponentially with increasing deformation. The ultimate tensile strength of the composite increased rapidly with increased deformation, especially at high deformation processing strains. The relation between deformation true strain and ultimate tensile strength is underestimated by the rule of mixtures; a modified Hall–Petch barrier strengthening model was found to fit the data better.

  18. Ca-rich Ca-Al-oxide, high-temperature-stable sorbents prepared from hydrotalcite precursors: synthesis, characterization, and CO2 capture capacity.

    PubMed

    Chang, Po-Hsueh; Chang, Yen-Po; Chen, San-Yuan; Yu, Ching-Tsung; Chyou, Yau-Pin

    2011-12-16

    We present the design and synthesis of Ca-rich Ca-Al-O oxides, with Ca(2+)/Al(3+) ratios of 1:1, 3:1, 5:1, and 7:1, which were prepared by hydrothermal decomposition of coprecipitated hydrotalcite-like Ca-Al-CO(3) precursors, for high-temperature CO(2) adsorption at 500-700 °C. In situ X-ray diffraction measurements indicate that the coprecipitated, Ca-rich, hydrotalcite-like powders with Ca(2+)/Al(3+) ratios of 5:1 and 7:1 contained Ca(OH)(2) and layered double hydroxide (LDH) phases. Upon annealing, LDH was first destroyed at approximately 200 °C to form an amorphous matrix, and then at 450-550 °C, the Ca(OH)(2) phase was converted into a CaO matrix with incorporated Al(3+) to form a homogeneous solid solution without a disrupted lattice structure. CaO nanocrystals were grown by thermal treatment of the weakly crystalline Ca-Al-O oxide matrix. Thermogravimetric analysis indicates that a CO(2) adsorption capacity of approximately 51 wt. % can be obtained from Ca-rich Ca-Al-O oxides prepared by calcination of 7:1 Ca-Al-CO(3) LDH phases at 600-700 °C. Furthermore, a relatively high CO(2) capture capability can be achieved, even with gas flows containing very low CO(2) concentrations (CO(2)/N(2) = 10 %). Approximately 95.6 % of the initial CO(2) adsorption capacity of the adsorbent is retained after 30 cycles of carbonation-calcination. TEM analysis indicates that carbonation-promoted CaCO(3) formation in the Ca-Al-O oxide matrix at 600 °C, but a subsequent desorption in N(2) at 700 °C, caused the formation CaO nanocrystals of approximately 10 nm. The CaO nanocrystals are widely distributed in the weakly crystalline Ca-Al-O oxide matrix and are present during the carbonation-calcination cycles. This demonstrates that Ca-Al-O sorbents that developed through the synthesis and calcination of Ca-rich Ca-Al LDH phases are suitable for long-term cyclic operation in severe temperature environments.

  19. Cadmium Stabilization Efficiency and Leachability by CdAl4O7 Monoclinic Structure.

    PubMed

    Su, Minhua; Liao, Changzhong; Chuang, Kui-Hao; Wey, Ming-Yen; Shih, Kaimin

    2015-12-15

    This study investigated the stabilization efficiencies of using an aluminum-rich precursor to incorporate simulated cadmium-bearing waste sludge and evaluated the leaching performance of the product phase. Cadmium oxide and γ-alumina mixtures with various Cd/Al molar ratios were fired at 800-1000 °C for 3 h. Cadmium could be crystallochemically incorporated by γ-alumina into CdAl4O7 monoclinic phase and the reaction was strongly controlled by the treatment temperature. The crystal structure details of CdAl4O7 were solved and refined with the Rietveld refinement method. According to the structural refinement results, the stabilization efficiencies were quantified and expressed as a transformation ratio (TR) with optimized processing parameters. The preferred treatment temperature was found to be 950 °C for mixtures with a Cd/Al molar ratio of 1/4, as its TR value indicated the cadmium incorporation was nearly completed after a 3 h treatment scheme. Constant-pH leaching tests (CPLT) were conducted by comparing the leachability of the CdO and CdAl4O7 phases in a pH 4.0 environment. A remarkable reduction in cadmium leachability could be achieved via monoclinic CdAl4O7 structure formation to effectively stabilize hazardous cadmium in the waste stream. The CPLT and X-ray photoelectron spectroscopy (XPS) results suggested incongruent dissolution behavior during the leaching of the CdAl4O7 phase.

  20. Phosphate-sulfide assemblages and Al/Ca ratios in type-3 chondrites

    NASA Astrophysics Data System (ADS)

    Rubin, A. E.; Grossman, J. N.

    1985-09-01

    Electron microscopic examinations were carried out on various chondrites to re-examine previously reported anomalously high Al/Ca ratios. Polished thin sections of the three CV3, two CO3 and the Krymka LL3 chondrites were scanned to characterize the phosphate-sulfide inclusions. The formation of the assemblages was interpreted as proceeding in five steps, starting with the formation of metal grains with early nebular material and finishing with a reaction between schreibersite with Ca, O and Cl to form merrillite and chloropatite. The abundances of the observed assemblages were not high enough to imply Al/Ca ratios similar to whole-rocks. It is concluded that the specimens were originally examined with a broader electron beam than used to examine standard samples, and resulted in the anomalously high Al/Ca ratios.

  1. Phosphate-sulfide assemblages and Al/Ca ratios in type-3 chondrites

    NASA Technical Reports Server (NTRS)

    Rubin, A. E.; Grossman, J. N.

    1985-01-01

    Electron microscopic examinations were carried out on various chondrites to re-examine previously reported anomalously high Al/Ca ratios. Polished thin sections of the three CV3, two CO3 and the Krymka LL3 chondrites were scanned to characterize the phosphate-sulfide inclusions. The formation of the assemblages was interpreted as proceeding in five steps, starting with the formation of metal grains with early nebular material and finishing with a reaction between schreibersite with Ca, O and Cl to form merrillite and chloropatite. The abundances of the observed assemblages were not high enough to imply Al/Ca ratios similar to whole-rocks. It is concluded that the specimens were originally examined with a broader electron beam than used to examine standard samples, and resulted in the anomalously high Al/Ca ratios.

  2. Formation Mechanism of CaS-Bearing Inclusions and the Rolling Deformation in Al-Killed, Low-Alloy Steel with Ca Treatment

    NASA Astrophysics Data System (ADS)

    Xu, Guang; Jiang, Zhouhua; Li, Yang

    2016-08-01

    The existing form of CaS inclusion in Ca-treated, Al-killed steel during secondary refining process was investigated with scanning electron microscopy and an energy-dispersive spectrometer (EDS). The results of 12 heats industrial tests showed that CaS has two kinds of precipitation forms. One form takes place by the direct reaction of Ca and S, and the other takes place by the reaction of CaO in calcium aluminates with dissolved Al and S in liquid steel. Thermodynamic research for different precipitation modes of CaS under different temperature was carried out. In particular, CaO-Al2O3-CaS isothermal section diagrams and component activities of calcium aluminates were calculated by the thermodynamic software FactSage. By thermodynamic calculation, a precipitation-area diagram of oxide-sulfide duplex inclusion was established by fixing the sulfur content. The quantity of CaS, which was precipitated in a reaction between [Al], [S] and (CaO), can be calculated and predicted based on the precipitation-area diagram of oxide-sulfide duplex inclusion. Electron probe microanalysis and EDS were used for observing rolling deformation of different types of CaS-bearing inclusions during the rolling process. Low modification of calcium aluminates wrapped by CaS has different degrees of harm to steel in the rolling process. A thick CaS layer can prevent some fragile calcium aluminates from being crushed during the rolling process. Some oxide-sulfide duplex inclusion contains little CaS performed better deformation during the rolling process, but when CaS in oxide-sulfide duplex inclusion becomes more, it will cause the whole inclusion to lose plastic yielding ability. The plastic deformation region of CaS-bearing inclusion in a CaO-Al2O3-CaS isothermal section diagram is confirmed.

  3. Temperature variation of the size effect in dilute AlMg and AlCa alloys: Measurement and theory

    NASA Astrophysics Data System (ADS)

    Gilder, H. M.; Asty, M.; Audit, Ph.

    1980-12-01

    Optical-interferometric-differential-length and x-ray lattice-parameter measurements performed at low temperatures in dilute AlMg and AlCa alloys indicate that the temperature variation of the size effect corresponds to a relatively large difference between the intrinsic coefficient of thermal expansion βi of the solute atom structure and that, β, of the solvent. This result is another example of the surprising expansive properties of point defects previously described by Gilder and co-workers (high-temperature vacancy diffusion) and more recently by Ganne (low-temperature dilatometry on irradiated specimens). Specifically, in the temperature range 0.2Ca)β~-4. This, as well as the fact that the sign of the change in the coefficient of thermal expansion Δβ of the host metal caused by the introduction of the solute atom is positive for Mg and negative for Ca, indicates that solute-solvent valence effects play a minor role in determining the coefficient of thermal expansion of the dilute alloy. It is also found, to within the experimental precision, that Δβ(Mg) and Δβ(Ca) are temperature independent, suggesting a type of Matthiessen's rule for thermal expansion. A model calculation of the size effect and its temperature variation in the infinitely dilute alloy is presented. The volume-dependent forces are treated by means of a term describing the elastic energy associated with the solute-solvent volume misfit, whereas the temperature-dependent potential of Dagens et al. is used to calculate the pairwise interaction between the solvent ions and the solute ion. Good agreement with the experimental data is obtained for the size effect in both AlMg and AlCa. The calculated values of Δβ(Mg)Ci, Ci being the solute concentration, and βi(Mg) fall between the measured values in the two AlMg alloys studied. The calculation of Δβ(Ca)Ci and βi(Ca) is not possible due to a lack of elastic-constants data for pure, metallic

  4. Optical properties of the giant dielectric material CaCu_3Ti_4O_12 and CdCu_3Ti_4O_12 \\unboldmath

    NASA Astrophysics Data System (ADS)

    Homes, Christopher

    2002-03-01

    The cubic perovskite-related oxide CaCu_3Ti_4O_12 has one of the largest dielectric constants at room temperature ever measured, ɛ_0~= 80 000, [ɛ_0≈ ɛ_1(ω arrow 0)]; ɛ0 drops by a factor of 1000 below about 100 K to ɛ_0~= 100, but curiously no change in the crystallographic structure is observed. The substitution of Cd for Ca results in a much lower value for the dielectric constant of ɛ_0~= 500, but the same general temperature dependence. The temperature-dependent reflectance of CaCu_3Ti_4O_12 and CdCu_3Ti_4O_12 has been measured over a wide frequency range, and the real and imaginary parts of the complex dielectric function were calculated from a Kramers-Kronig analysis. The optical properties are dominated by the unscreened lattice modes. There are a total of 11 infrared-active Tu modes expected; all 11 modes are observed in the CdCu_3Ti_4O_12 material, but only 10 are found in CaCu_3Ti_4O_12; the mode at ≈ 480 cm-1 is absent. The low frequency mode at ≈ 120 cm-1 in CaCu_3Ti_4O_12 shows an anomalous increase in oscillator strength at low temperature, in violation of the f-sum rule.(C.C. Homes et al.), Science 293, 673 (2001). The same behavior is found, although to a lesser extent, in the Cd material. A normal coordinate analysis of the vibrational modes indicates that the low-frequency mode involves primarily the Ca(Cd) atoms, as well as the Cu-O sublattice. The increase in strength of this mode is an indication that this bonding is becoming more ionic, implying that there is a redistribution of charge on this sublattice at low temperature. This suggests that the electric fields responsible for the large value of ɛ0 may originate not from the TiO6 octahedra, as is often seen in ferroelectrics, but from the Ca/Cu-O sublattice. A possible mechanism for the reduction of ɛ0 at low temperature will be discussed in light of recent high-resolution structural studies.

  5. Comparative Studies on Temperature Dependent I-V Characteristics of Al/(p)CdTe and Ni/(n)CdS Schottky Junctions and Their PV Effect

    SciTech Connect

    Wary, G.; Kachari, T.; Rahman, A.

    2010-06-29

    Temperature dependent I-V characteristics of vacuum evaporated Al/(p)CdTe and Ni/(n)CdS Schottky junctions and their photovoltaic effects have been studied and compared. Different junction parameters such as ideality factors, barrier heights, Richardson's constant, short-circuit current density, fill factor, PV efficiency etc. were determined from their I-V characteristics. These parameters were found to change significantly on variation of temperature. The structures showed the change of PV effect. Efficiency found were 2.84% for Al/(p)CdTe and 4.44% for Ni hydro/(n)CdS. Polycrystalline nature, and continuous and ordered structure with bigger grain sizes of the CdS film shows more PV conversion efficiency in making Ni/(n)CdS junction as compare to Al/(p)CdTe junction. However these values were found to vary with doping concentration, and in hydrogen treated samples in both cases.

  6. Effect of Ca addition on the corrosion behavior of Mg-Al-Mn alloy

    NASA Astrophysics Data System (ADS)

    Yang, Jiang; Peng, Jian; Nyberg, Eric A.; Pan, Fu-sheng

    2016-04-01

    The microstructures and corrosion resistance of magnesium-5 wt% aluminum-0.3 wt% manganese alloys (Mg-Al-Mn) with different Ca additions (0.2-4 wt%) were investigated. Results showed that with increasing Ca addition, the grain of the alloys became more refined, whereas the corrosion resistant ability of the alloys initially increased and then decreased. The alloy with 2 wt% Ca addition exhibited the best corrosion resistance, attributed to the effect of the oxide film and (Mg,Al)2Ca phases which were discontinuously distributed on the grain boundaries. These phases acted as micro-victims, they preferentially corroded to protect the α-Mg matrix. The oxide film formed on the alloy surface can hinder the solution further to protect the α-Mg matrix.

  7. Density Measurements of Low Silica CaO-SiO2-Al2O3 Slags

    NASA Astrophysics Data System (ADS)

    Muhmood, Luckman; Seetharaman, Seshadri

    2010-08-01

    Density measurements of a low-silica CaO-SiO2-Al2O3 system were carried out using the Archimedes principle. A Pt 30 pct Rh bob and wire arrangement was used for this purpose. The results obtained were in good agreement with those obtained from the model developed in the current group as well as with other results reported earlier. The density for the CaO-SiO2 and the CaO-Al2O3 binary slag systems also was estimated from the ternary values. The extrapolation of density values for high-silica systems also showed good agreement with previous works. An estimation for the density value of CaO was made from the current experimental data. The density decrease at high temperatures was interpreted based on the silicate structure. As the mole percent of SiO2 was below the 33 pct required for the orthosilicate composition, discrete {text{SiO}}4^{4 - } tetrahedral units in the silicate melt would exist along with O2- ions. The change in melt expansivity may be attributed to the ionic expansions in the order of {text{Al}}^{ 3+ } - {text{O}}^{ 2- } < {text{Ca}}^{ 2+ } - {text{O}}^{ 2- } < {text{Ca}}^{ 2+ } - {text{O}}^{ - } Structural changes in the ternary slag also could be correlated to a drastic change in the value of enthalpy of mixing.

  8. Influence of Al doping on optical properties of CdS/PVA nanocomposites: Theory and experiment

    SciTech Connect

    Bala, Vaneeta Tripathi, S. K. Kumar, Ranjan

    2014-04-24

    In the present work theoretical and experimental studies of aluminium doped cadmium sulphide polyvinyl alcohol (Al:CdS/PVA) nanocomposites have been carried out. Tetrahedral cluster AlCd{sub 9}S{sub 2}(SH){sub 18}]{sup 1−} has been encapsulated by small segments of polyvinyl alcohol (PVA) chains in order to simulate experimental environment of nanocomposites. Density functional theory (DFT) using local density approximation (LDA) functionals is employed to study the broadening of band gap upon ligation of nanoclusters. We have used in situ chemical route to synthesize nanocomposites. Optical band gap has been calculated from both experimental and theoretical approach.

  9. Human gallbladder carcinoma: Role of neurotrophins, MIB-1, CD34 and CA15-3.

    PubMed

    Artico, M; Bronzetti, E; Alicino, V; Ionta, B; Bosco, S; Grande, C; Bruno, M; Tranquilli Leali, F M; Ionta, G; Fumagalli, L

    2010-03-11

    Gallbladder carcinoma is the most common biliary tract tumor and the fifth most common gastrointestinal tract cancer .The prognosis of gallbladder carcinoma is poor and less than 5% of the patients are still alive five years postoperatively. Gallbladder specimens were obtained during surgical operations performed in eleven patients for resection of a gallbladder carcinoma, and during five autopsies (control cases selected among patients who died from for other causes, excluding those suffering from biliary or hepatic diseases). Immunohistochemical characterization and distribution of neurotrophins, with their respective receptors, were analyzed. The actual role played by these neurotrophic factors in the general regulation, vascular permeability, algic responsiveness, release of locally active substances and potential tumorigenesis in the gallbladder and biliary ducts compartment remains controversial. Our study revealed an increased immunohistochemical expression of NGF and TrKA in the epithelium and in the epithelial glands of the gallbladder carcinoma together with an evident immunoreactivity for BDNF in the same neoplastic areas. An evident immunoreactivity for NGF, TrKA and BDNF was observed in control specimens of gallbladder obtained during autopsies, whereas a weak or quite absent immunoreactivity was observed in the same specimens for NT4, TrKC and p75. On the contrary an appreciable immunoreactivity for p75 was observed in the specimens harvested from patients with gallbladder carcinoma. We also investigated the expression of some known tumor markers such as MIB-1 (anti Ki-67), CD34 and CA15-3, to identify a possible correlation between the expression of these molecular factors and the prognosis of gallbladder carcinoma. They resulted highly expressed in the stroma (CD34 and CA 15-3) and in the epithelium/epithelial glands (MIB-1) of the neoplastic areas and appeared to be almost absent in the control cases, suggesting that these markers, taken together

  10. Chemical short-range order and the Meyer - Neldel rule for liquid alloys: AlCa and GaAlCa

    NASA Astrophysics Data System (ADS)

    You, D.; Schnyders, H. S.; Van Zytveld, J. B.

    1997-02-01

    We have measured the electrical resistivity, 0953-8984/9/7/006/img1, its specific temperature dependence, 0953-8984/9/7/006/img2, and the thermopower, S, of two series of ternary liquid alloys: 0953-8984/9/7/006/img3 and 0953-8984/9/7/006/img4. We also provide new analysis for the binary liquid alloy AlCa. We do not see the unusually large values for S that were found earlier for amorphous solid ternary alloys of the approximate composition 0953-8984/9/7/006/img5. We do find that, while chemical short-range order (CSRO) appears to occur in the liquid binary alloy 0953-8984/9/7/006/img6, CSRO is apparently destroyed by substitution of one Ga atom for one Al per complex: 0953-8984/9/7/006/img7. CSRO may exist in the liquid alloy 0953-8984/9/7/006/img8. And we find that the activated conductivities of these ternary liquid alloys (and also of liquid AlCa) are consistent with the Meyer - Neldel rule (MNR), extending the range of applicability of the MNR to systems with activation energies about an order of magnitude smaller than previously observed. These results appear to rule out two physical models as universal bases for the MNR, but are consistent with one based on a hopping conductivity whose characteristic energy is that of a polaron shift.

  11. Mitochondrial Ca2+ and membrane potential, an alternative pathway for Interleukin 6 to regulate CD4 cell effector function

    PubMed Central

    Yang, Rui; Lirussi, Dario; Thornton, Tina M; Jelley-Gibbs, Dawn M; Diehl, Sean A; Case, Laure K; Madesh, Muniswamy; Taatjes, Douglas J; Teuscher, Cory; Haynes, Laura; Rincón, Mercedes

    2015-01-01

    IL-6 plays an important role in determining the fate of effector CD4 cells and the cytokines that these cells produce. Here we identify a novel molecular mechanism by which IL-6 regulates CD4 cell effector function. We show that IL-6-dependent signal facilitates the formation of mitochondrial respiratory chain supercomplexes to sustain high mitochondrial membrane potential late during activation of CD4 cells. Mitochondrial hyperpolarization caused by IL-6 is uncoupled from the production of ATP by oxidative phosphorylation. However, it is a mechanism to raise the levels of mitochondrial Ca2+ late during activation of CD4 cells. Increased levels of mitochondrial Ca2+ in the presence of IL-6 are used to prolong Il4 and Il21 expression in effector CD4 cells. Thus, the effect of IL-6 on mitochondrial membrane potential and mitochondrial Ca2+ is an alternative pathway by which IL-6 regulates effector function of CD4 cells and it could contribute to the pathogenesis of inflammatory diseases. DOI: http://dx.doi.org/10.7554/eLife.06376.001 PMID:25974216

  12. Effects of Ca, Cu, Al and La on pectin gel strength: implications for plant cell walls.

    PubMed

    McKenna, Brigid A; Nicholson, Timothy M; Wehr, J Bernhard; Menzies, Neal W

    2010-06-16

    Rheology of Ca-pectate gels is widely studied, but the behaviour of pectate gels formed by Cu, Al and La is largely unknown. It is well known that gel strength increases with increasing Ca concentration, and it is hypothesised that this would also be the case for other cations. Pectins are a critical component of plant cell walls, imparting various physicochemical properties. Furthermore, the mechanism of metal toxicity in plants is hypothesised to be, in the short term, related to metal interactions with cell wall pectin. This study investigated the influence of Ca, Cu, Al and La ion concentrations at pH 4 on the storage modulus as a function of frequency for metal-pectin gels prepared from pectin (1%) with a degree of esterification of 30%. Gels were formed in situ over 6d in metal chloride solution adjusted daily to pH 4. Cation concentration was varied to develop a relationship between gel strength and cation concentration. At similar levels of cation saturation, gel strength increased in the order of La<Ca < or =AlCa gels being the most swollen.

  13. Effects of Ca, Cu, Al and La on pectin gel strength: implications for plant cell walls.

    PubMed

    McKenna, Brigid A; Nicholson, Timothy M; Wehr, J Bernhard; Menzies, Neal W

    2010-06-16

    Rheology of Ca-pectate gels is widely studied, but the behaviour of pectate gels formed by Cu, Al and La is largely unknown. It is well known that gel strength increases with increasing Ca concentration, and it is hypothesised that this would also be the case for other cations. Pectins are a critical component of plant cell walls, imparting various physicochemical properties. Furthermore, the mechanism of metal toxicity in plants is hypothesised to be, in the short term, related to metal interactions with cell wall pectin. This study investigated the influence of Ca, Cu, Al and La ion concentrations at pH 4 on the storage modulus as a function of frequency for metal-pectin gels prepared from pectin (1%) with a degree of esterification of 30%. Gels were formed in situ over 6d in metal chloride solution adjusted daily to pH 4. Cation concentration was varied to develop a relationship between gel strength and cation concentration. At similar levels of cation saturation, gel strength increased in the order of La<Ca < or =AlCa gels being the most swollen. PMID:20457449

  14. Optically stimulated luminescence in LiCaAlF6:Eu2+ phosphor.

    PubMed

    More, Y K; Wankhede, S P; Moharil, S V; Kumar, Munish; Chougaonkar, M P

    2015-09-01

    Results on optically stimulated luminescence (OSL) in LiCaAlF6:Eu(2+) are reported. Continuous wave OSL signal as recorded using blue (470 nm) stimulation was found to be ~31% that of standard phosphor lithium magnesium phosphate. The rate of OSL depletion for standard phosphor lithium magnesium phosphate is only three times less as compared with that of LiCaAlF6:Eu(2+). Strong photoluminescence (PL) in the near ultraviolet region is observed for LiCaAlF6:Eu(2+) with the characteristic Eu(2+) emission at 369 nm for 254 nm excitation. The thermoluminescence (TL) glow peak for LiCaAlF6:Eu(2+) was observed at around 180°C. The glow peak was about six times more intense compared with the dosimetric peak of the well known thermoluminescence dosimetric (TLD) phosphor LiF-TLD 100. Thus this phosphor deserves much more attention than it has received until now and may be useful as a dosimetric material in radiation dosimetry. PMID:25620581

  15. Formation Mechanism of CaS-Al2O3 Inclusions in Low Sulfur Al-Killed Steel After Calcium Treatment

    NASA Astrophysics Data System (ADS)

    Xu, Jianfei; Huang, Fuxiang; Wang, Xinhua

    2016-04-01

    The laboratory experiments of alumina inclusions modified by calcium treatment in Al-killed steel were carried out at 1873 K (1600 °C), and the inclusions in steel samples were characterized at 1, 5, and 10 minutes after calcium addition. The results show that the type of inclusions after calcium treatment was determined by the sulfur and T.O contents of steel. CaS-Al2O3 inclusions were obtained in steels with high sulfur and low T.O contents. The mass ratio between CaS and Al2O3 was determined by T.Ca and T.O contents of steel. The influence of holding time after calcium addition on the composition of inclusions was negligible. The thermodynamics for the formation of CaS-Al2O3 inclusions after calcium treatment was discussed, and a simple formation mechanism was proposed. Moreover, the CaO, Al2O3, and CaS contents in the inclusions were predicted through the sulfur, total calcium (T.Ca), and T.O contents, and it was found that the CaO content decreases with increasing S/T.O, while (pctCaS)/(pctAl2O3)1/3 increases with increasing T.Ca/T.O.

  16. Ca-,Al-rich inclusions in the unique chondrite ALH85085 - Petrology, chemistry, and isotopic compositions

    NASA Astrophysics Data System (ADS)

    Kimura, M.; El Goresy, A.; Palme, H.; Zinner, E.

    1993-05-01

    A comprehensive study is performed for the Ca-,Al-rich inclusions (CAIs) in the unique chondrite ALH85085. The ALH85085 inclusions are smaller (5-80 microns) and more refractory than their counterparts in carbonaceous chondrites. The study includes 42 inclusions for petrography and mineralogy, 15 for bulk major and minor element chemical composition, six for Mg-Al isotopic systematics, 10 for Ca isotopes, nine for Ti isotopes, and six for trace element abundances. In addition, oxygen-isotopic compositions were determined in minerals from a single inclusion. No correlation is found between mineralogy, major element chemistry, and trace element abundances. It is further shown that the high-temperature geochemical behavior of ultrarefractory trace elements is decoupled from that of the major elements Ca and Ti (Ti is correlated with the relatively volatile elements Nb and Yb) implying that perovskite is of only minor importance as carrier of ultrarefractories.

  17. Effect of alloying elements Al and Ca on corrosion resistance of plasma anodized Mg alloys

    NASA Astrophysics Data System (ADS)

    Anawati, Asoh, Hidetaka; Ono, Sachiko

    2016-04-01

    Plasma anodizing is a surface treatment used to form a ceramic-type oxide film on Mg alloys by the application of a high anodic voltage to create intense plasma near the metal surface. With proper selection of the process parameters, the technique can produce high quality oxide with superior adhesion, corrosion resistance, micro-hardness, wear resistance and strength. The effect of alloying element Al on plasma anodizing process of Mg alloys was studied by comparing the anodizing curves of pure Mg, AZ31, and AZ61 alloys while the effect of Ca were studied on AZ61 alloys containing 0, 1, and 2 wt% Ca. Anodizing was performed in 0.5 M Na3PO4 solution at a constant current density of 200 Am-2 at 25°C. Anodic oxide films with lava-like structure having mix composition of amorphous and crystal were formed on all of the alloys. The main crystal form of the oxide was Mg3(PO4)2 as analyzed by XRD. Alloying elements Al and Ca played role in modifying the plasma lifetime during anodization. Al tended to extend the strong plasma lifetime and therefore accelerated the film thickening. The effect of Ca on anodizing process was still unclear. The anodic film thickness and chemical composition were altered by the presence of Ca in the alloys. Electrochemical corrosion test in 0.9% NaCl solution showed that the corrosion behavior of the anodized specimens depend on the behavior of the substrate. Increasing Al and Ca content in the alloys tended to increase the corrosion resistance of the specimens. The corrosion resistance of the anodized specimens improved significantly about two orders of magnitude relative to the bare substrate.

  18. Thermochemistry of glasses and liquids in the systems CaMgSi 2O 6-CaAl 2Si 2O 8-NaAlSi 3O 8, SiO 2-CaAl 2Si 2O 8-NaAlSi 3O 8 and SiO 2-Al 2O 3-CaO-Na 2O

    NASA Astrophysics Data System (ADS)

    Navrotsky, A.; Hon, R.; Weill, D. F.; Henry, D. J.

    1980-10-01

    Enthalpies of solution in 2PbO· B 2O 3 at 712°C have been measured for glasses in the systems albite anorthite diopside, NaAlO 2-SiO 2, Ca 0.5AlO 2-SiO 2 and albite-anorthite-quartz. The systems albite-anorthite and diopside-anorthite show substantial negative enthalpies of mixing, albite-diopside shows significant positive heats of mixing. For compositions up to NaAlO2 = 0.42 (which includes the subsystem albite-silica) the system NaAlO 2-SiO 2 shows essentially zero heats of mixing. A negative ternary excess heat of mixing is found in the plagioclase-rich portion of the albite-anorthite-diopside system. The join Si 4O 8-CaAl 2Si 2O 8 shows small but significant heats of mixing. In albite-anorthite-quartz. ternary glasses, the ternary excess enthalpy of mixing is positive. Based on available heat capacity data and appropriate consideration of the glass transition, the enthalpy of the crystal-glass transition (vitrification) is a serious underestimate of the enthalpy of the crystal-liquid transition (fusion) especially when the melting point, Tf, is many hundreds of degrees higher than the glass transition temperature, Tg. On the other hand, the same heat capacity data suggest that the enthalpies of mixing in albite-anorthite-diopside liquids are calculated to be quite similar to those in the glasses. The enthalpies of mixing observed in general support the structural models proposed by TAYLOR and BROWN (1979a, b) and others for the structure of aluminosilicate glasses.

  19. Optically pumped cerium-doped LiSrAlF.sub.6 and LiCaAlF.sub.6

    DOEpatents

    Marshall, Christopher D.; Payne, Stephen A.; Krupke, William F.

    1996-01-01

    Ce.sup.3+ -doped LiSrAlF.sub.6 crystals are pumped by ultraviolet light which is polarized along the c axis of the crystals to effectively energize the laser system. In one embodiment, the polarized fourth harmonic light output from a conventional Nd:YAG laser operating at 266 nm is arranged to pump Ce:LiSrAlF.sub.6 with the pump light polarized along the c axis of the crystal. The Ce:LiSrAlF.sub.6 crystal may be placed in a laser cavity for generating tunable coherent ultraviolet radiation in the range of 280-320 nm. Additionally, Ce-doped crystals possessing the LiSrAlF.sub.6 type of chemical formula, e.g. Ce-doped LiCaAlF.sub.6 and LiSrGaF.sub.6, can be used. Alternative pump sources include an ultraviolet-capable krypton or argon laser, or ultraviolet emitting flashlamps. The polarization of the pump light will impact operation. The laser system will operate efficiently when light in the 280-320 nm gain region is injected or recirculated in the system such that the beam is also polarized along the c axis of the crystal. The Ce:LiSrAlF.sub.6 laser system can be configured to generate ultrashort pulses, and it may be used to pump other devices, such as an optical parametric oscillator.

  20. Optically pumped cerium-doped LiSrAlF{sub 6} and LiCaAlF{sub 6}

    DOEpatents

    Marshall, C.D.; Payne, S.A.; Krupke, W.F.

    1996-05-14

    Ce{sup 3+}-doped LiSrAlF{sub 6} crystals are pumped by ultraviolet light which is polarized along the c axis of the crystals to effectively energize the laser system. In one embodiment, the polarized fourth harmonic light output from a conventional Nd:YAG laser operating at 266 nm is arranged to pump Ce:LiSrAlF{sub 6} with the pump light polarized along the c axis of the crystal. The Ce:LiSrAlF{sub 6} crystal may be placed in a laser cavity for generating tunable coherent ultraviolet radiation in the range of 280-320 nm. Additionally, Ce-doped crystals possessing the LiSrAlF{sub 6} type of chemical formula, e.g. Ce-doped LiCaAlF{sub 6} and LiSrGaF{sub 6}, can be used. Alternative pump sources include an ultraviolet-capable krypton or argon laser, or ultraviolet emitting flashlamps. The polarization of the pump light will impact operation. The laser system will operate efficiently when light in the 280-320 nm gain region is injected or recirculated in the system such that the beam is also polarized along the c axis of the crystal. The Ce:LiSrAlF{sub 6} laser system can be configured to generate ultrashort pulses, and it may be used to pump other devices, such as an optical parametric oscillator. 10 figs.

  1. Study of two tungstates Ca0.5 Cd0.5 WO4 and Ca0.2 Cd0.8 WO4 by transmission electron microscopy.

    PubMed

    Taoufyq, A; Patout, L; Guinneton, F; Benlhachemi, A; Bakiz, B; Villain, S; Lyoussi, A; Nolibe, G; Gavarri, J-R

    2015-01-01

    To better understand the role of crystal structures and local disorder in the photonic properties of the system (1 - x)CaWO4  - xCdWO4 with 0 < x < 1, two specific phases with compositions x = 0.5 (scheelite phase) and 0.8 (wolframite phase) have been studied by scanning and transmission electron microscopies. High-resolution electron microscopy images and image simulations, associated with X-ray diffraction data, allowed confirming the lattices and space groups I41 /a and P2/c of the two scheelite and wolframite phases, at the local scale. The electron microscopy data show the existence of a high degree of crystallization associated with statistical distribution of Ca or Cd atoms on a Ca1- x Cdx site in each lattice. PMID:26372831

  2. Combustion Synthesis of CaAl2Si2O8:Eu2+, Dy3+ And CaSrAl2SiO7:Eu2+ Long After Glow Phosphors

    NASA Astrophysics Data System (ADS)

    Talwar, Gurjeet; Joshi, C. P.; Moharil, S. V.; Kondawar, V. K.

    2011-10-01

    CaSrAl2SiO7:Eu2+ and CaAl2Si2O8:Eu2+, Dy3+ are prepared through modified combustion technique. The photoluminescence and long after glow decay characteristics are studied. PL emission spectra of both the phosphors are obtained in blue region.

  3. Aluminum-Magnesium and Oxygen Isotope Study of Relict Ca-Al-rich Inclusions in Chondrules

    NASA Astrophysics Data System (ADS)

    Krot, Alexander N.; McKeegan, Kevin D.; Huss, Gary R.; Liffman, Kurt; Sahijpal, Sandeep; Hutcheon, Ian D.; Srinivasan, Gopalan; Bischoff, Adolph; Keil, Klaus

    2006-03-01

    Relict Ca-Al-rich inclusions (CAIs) in chondrules crystallized before their host chondrules and were subsequently partly melted together with chondrule precursors during chondrule formation. Like most CAIs, relict CAIs are 16O enriched (Δ17O<-20‰) compared to their host chondrules (Δ17O>-9‰). Hibonite in a relict CAI from the ungrouped carbonaceous chondrite Adelaide has a large excess of radiogenic 26Mg (26Mg*) from the decay of 26Al, corresponding to an initial 26Al/27Al ratio [(26Al/27Al)I] of (3.7+/-0.5)×10-5 in contrast, melilite in this CAI and plagioclase in the host chondrule show no evidence for 26Mg* [(26Al/27Al)I of <5×10-6]. Grossite in a relict CAI from the CH carbonaceous chondrite PAT 91546 has little 26Mg*, corresponding to a (26Al/27Al)I of (1.7+/-1.3)×10-6. Three other relict CAIs and their host chondrules from the ungrouped carbonaceous chondrite Acfer 094, CH chondrite Acfer 182, and H3.4 ordinary chondrite Sharps do not have detectable 26Mg* [(26Al/27Al)I<1×10-5, <(4-6)×10-6, and <1.3×10-5, respectively]. Isotopic data combined with mineralogical observations suggest that relict CAIs formed in an 16O-rich gaseous reservoir before their host chondrules, which originated in an 16O-poor gas. The Adelaide CAI was incorporated into its host chondrule after 26Al had mostly decayed, at least 2 Myr after the CAI formed, and this event reset 26Al-26Mg systematics.

  4. Development of aluminum (Al5083)-clad ternary Ag In Cd alloy for JSNS decoupled moderator

    NASA Astrophysics Data System (ADS)

    Teshigawara, M.; Harada, M.; Saito, S.; Oikawa, K.; Maekawa, F.; Futakawa, M.; Kikuchi, K.; Kato, T.; Ikeda, Y.; Naoe, T.; Koyama, T.; Ooi, T.; Zherebtsov, S.; Kawai, M.; Kurishita, H.; Konashi, K.

    2006-09-01

    To develop Ag (silver)-In (indium)-Cd (cadmium) alloy decoupler, a method is needed to bond the decoupler between Al alloy (Al5083) and the ternary Ag-In-Cd alloy. We found that a better HIP condition was temperature, pressure and holding time at 803 K, 100 MPa and 10 min. for small test pieces ( ϕ22 mm in dia. × 6 mm in height). Hardened layer due to the formation of AlAg 2 was found in the bonding layer, however, the rupture strength of the bonding layer is more than 30 MPa, the calculated design stress. Bonding tests of a large size piece (200 × 200 × 30 mm 3), which simulated the real scale, were also performed according to the results of small size tests. The result also gave good bonding and enough required-mechanical-strength.

  5. Crystal structure study of (Ca, Gd){sub 2}(Al, Ti)O{sub 4}

    SciTech Connect

    Sawada, Haruo; Marumo, Fumiyuki; Kodama, Nobuhiro

    1998-08-01

    The crystal structures of two crystals of (Ca, Gd){sub 2} (Al, Ti)O{sub 4} [tetragonal I4/mmm; Z = 4], one strongly fluorescent and the other weakly fluorescent, having minor differences in their precise compositions have been studied with single-crystal X-ray diffraction methods. The unit cell is significantly smaller for the weakly fluorescent crystal, which also shows alteration of the coordination polyhedraon around the (Ca, Gd) site, suggesting the formation of vacancies at an oxygen site.

  6. Thermal transformation of quaternary compounds in NaF-CaF{sub 2}-AlF{sub 3} system

    SciTech Connect

    Zaitseva, Julia N.; Yakimov, Igor S.; Kirik, Sergei D.

    2009-08-15

    Details of quaternary compounds formation in the system NaF-CaF{sub 2}-AlF{sub 3} are specified. To achieve this aim, the samples of phases NaCaAlF{sub 6} and Na{sub 2}Ca{sub 3}Al{sub 2}F{sub 14} have been obtained by high-temperature solid-phase synthesis. Their thermal behavior when heated up to 800 deg. C has been studied using the methods of high-temperature X-ray diffraction (XRD) and thermal analysis (TA). The system under consideration can be regarded as a quasibinary section CaF{sub 2}-NaAlF{sub 4}, where at T=745-750 deg. C invariant equilibrium is implemented with the phases CaF{sub 2}-NaCaAlF{sub 6}-Na{sub 2}Ca{sub 3}Al{sub 2}F{sub 14}-(liquid melt)-(NaAlF{sub 4}). The peculiarity of the equilibrium is NaAlF{sub 4} metastability at normal pressure. Below the equilibrium temperature the quaternary phase Na{sub 2}Ca{sub 3}Al{sub 2}F{sub 14} is stable and NaCaAlF{sub 6} above this temperature. The phase NaCaAlF{sub 6} fixed by rapid quenching from high temperatures and when heated up to 640 deg. C decomposes, yielding Na{sub 2}Ca{sub 3}Al{sub 2}F{sub 14}. Further heating in vacuum at temperature up to 740 deg. C results in decomposition of Na{sub 2}Ca{sub 3}Al{sub 2}F{sub 14} into CaF{sub 2} and Na{sub 3}AlF{sub 6}. The expected reverse transformation of Na{sub 2}Ca{sub 3}Al{sub 2}F{sub 14} into NaCaAlF{sub 6} has not been observed under experimental conditions. Transformations in bulk samples reveal direct and reverse transformation of quaternary phases. Synopsis: Thermal transformation of the quaternary compounds in system (NaF-CaF{sub 2}-AlF{sub 3}) was investigated using high-temperature X-ray diffraction (XRD) and thermal analysis (TA). In the system the invariant equilibrium is implemented with the phases CaF{sub 2}-NaCaAlF{sub 6}-Na{sub 2}Ca{sub 3}Al{sub 2}F{sub 14}-(liquid melt)-(NaAlF{sub 4}) at T=745-750 deg. C. - Graphical Abstract: The paper concerns of a small piece of the ternary system (NaF-CaF{sub 2}-AlF{sub 3}) which is very important for

  7. Origin of Ca-Al-rich inclusions. II - Sputtering and collisions in the three-ph8se interstellar medium

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.

    1981-01-01

    The theory put forward by Clayton (1977) for the formation of the Ca-Al-rich inclusions within C3 meteorites is extended to an evolutionary history in a three-phase interstellar medium. Widespread supersonic turbulence in the hot interstellar medium is maintained by supernova shock waves, giving rise to heavy sputtering of the refractory dust. Subsequent reaccumulation with varying dust/gas ratios or varying particle sizes produces isotopically fractionated Ca-Al-rich accumulates. It is thought that the Ca-Al-rich inclusions themselves are formed by the following sequence in the solar system: (1) cold accumulation of larger-than-average Ca-Al-rich particles containing supernova condensate cores into macroscopic (approximately 1 cm) Ca-Al-rich agglomerates, probably by sedimentation; and (2) fusion of the supernova condensates into macroscopic minerals by exothermic chemical reactions that begin when the accumulate has been warmed, thereby releasing energy from the unequilibrated forms accumulated from the interstellar medium.

  8. Experiments TGV I (double-beta decay of 48Ca) and TGV II (double-beta decay of 106Cd and 48Ca)

    NASA Astrophysics Data System (ADS)

    Štekl, I.; Čermák, P.; Beneš, P.; Brudanin, V. B.; Rukhadze, N. I.; Egorov, V. G.; Kovalenko, V. E.; Kovalík, A.; Salamatin, A. V.; Tsoupko-Sitnikov, V. V.; Vylov, Ts.; Briancon, Ch.; Šimkovic, F.

    2000-04-01

    Present status of experiments TGV I and TGV II is given. The TGV I collaboration has studied the double-beta decay of 48Ca with a low-background and high sensitivity Ge multi-detector spectrometer TGV (Telescope Germanium Vertical). The preliminary results of years and years (90% CL) for double-beta decay of 48 Ca has been found after the processing of experimental data obtained after 8700 hours of measuring time using approximately 1 gramme of 48Ca. The aim of the experiment TGV II is the development of the experimental methods, construction of spectrometers and measurement of the decay (++, β+/EC, EC/EC) of 106Cd particularly the 2νEC/EC mode. The theoretical description and performance of the TGV II spectrometer are also given.

  9. Observations of the Minor Species Al, Fe and Ca(+) in Mercury's Exosphere

    NASA Technical Reports Server (NTRS)

    Bida, Thomas A.; Killen, Rosemary M.

    2011-01-01

    We report the first detections of Al and Fe, and strict upper limits for Ca(+) in the exosphere of Mercury, using the HIRES spectrometer at the Keck I telescope. We report observed 4-sigma tangent columns of 1.5x10(exp 7) Al atoms per square centimeter at an altitude of 1220 km (1.5 Mercury radii (R(sub M)) from planet center), and that for Fe of 1.6 x 10 per square centimeter at an altitude of 950 km (1.4 R(sub M)). The observed 3-sigma Ca(+) column was 3.9x10(exp 6) ions per square centimeter at an altitude of 1630 km (1.67 R(sub M). A simple model for zenith column abundances of the neutral species were 9.5 x 10(exp 7) Al per square centimeter, and 3.0 x 10(exp 8) Fe per square centimeter. The observations appear to be consistent with production of these species by impact vaporization with a large fraction of the ejecta in molecular form. The scale height of the Al gas is consistent with a kinetic temperature of 3000 - 9000 K while that of Fe is 10500 K. The apparent high temperature of the Fe gas would suggest that it may be produced by dissociation of molecules. A large traction of both Al and Fe appear to condense in a vapor cloud at low altitudes.

  10. Sr isotopic fractionation in Ca-Al inclusions from the Allende meteorite

    USGS Publications Warehouse

    Patchett, P.J.

    1980-01-01

    True relative Sr isotopic compositions, determined by double spiking on Ca-Al inclusions from the Allende meteorite show up to 1.5??? per mass unit mass fractionation relative to the Earth and bulk chondrites. All abnormal inclusions are light-isotope enriched. A lack of isotopically heavy Sr in inclusions would place constraints on the time, place and mechanism of origin of these objects. ?? 1980 Nature Publishing Group.

  11. Evidence from Cd/Ca ratios in foraminifera for greater upwelling off California 4,000 years ago

    USGS Publications Warehouse

    VanGeen, A.; Luoma, N.; Fuller, C.C.; Anima, R.; Clifton, H.E.; Trumbore, S.

    1992-01-01

    UPWELLING of nutrient-rich Pacific deep water along the North American west coast is ultimately driven by the temperature difference between air masses over land and over the ocean. The intensity of upwelling, and biological production in the region, could therefore be affected by anthropogenic climate change. Examination of the geological record is one way to study the link between climate and upwelling. Because Pacific deep water is enriched in cadmium, dissolved cadmium concentrations in coastal water off central California reflect the intensity of upwelling. By demonstrating that the Cd/Ca ratio in the shell of a benthic foraminifer, Elphidiella hannai, is proportional to the Cd concentration in coastal water, we show here that foraminiferal Cd/Ca ratios can be used to detect past changes in mean upwelling intensity. Examination of a sediment core from the mouth of San Francisco Bay reveals that foraminiferal Cd/Ca decreased by about 30% from 4,000 years ago to the present, probably because of a reduction in coastal upwelling. This observation is consistent with predictions of atmospheric general circulation models that northwesterly winds, which drive upwelling, became weaker over this period as summer insolation of the Northern Hemisphere decreased.

  12. Crystal growth, polarized spectra, and laser performance of Yb:CaGdAlO4 crystal

    NASA Astrophysics Data System (ADS)

    Di, J. Q.; Xu, X. D.; Xia, C. T.; Zheng, L. H.; Aka, G.; Yu, H. H.; Sai, Q. L.; Guo, X. Y.; Zhu, L.

    2016-04-01

    In this paper, the crystal growth, polarized spectra, and laser performance of Yb:CaGdAlO4 crystal were reported. The segregation coefficient of Yb3+ ions was calculated to be 0.47. The cell parameters were determined to be a  =  b  =  0.3658 nm, c  =  1.1985 nm. The peak absorption cross-section was calculated to be 2.65  ×  10-20 cm2 at 979 nm and the peak stimulated emission cross-section was 2.23  ×  10-20 cm2 at 980 nm for the π polarization. The continuous-wave (CW) laser operations of uncoated Yb:CaGdAlO4 crystals with 5  ×  5  ×  3 mm3 in size were demonstrated. A maximum output power of 1.6 W at 1048 nm was obtained with a slope efficiency of 28%. The results show that Yb:CaGdAlO4 crystal is a promising laser medium.

  13. Hibonite, Ca2/Al, Ti/24O38, from the Leoville and Allende chondritic meteorites.

    NASA Technical Reports Server (NTRS)

    Keil, K.; Fuchs, L. H.

    1971-01-01

    Hibonite was discovered in light-colored, Ca-Al-Ti-rich and Si-Fe-poor, achondritic inclusions of the Leoville and Allende HL-group chondrites. Two varieties of hibonite occur: one emits a bright red-orange luminescence under electron bombardment and has high amounts of Al2O3 (87.7; 87.9) and low amounts of MgO (0.65; 0.8) and TiO2 (0.68; 0.8). The other emits a bright blue luminescence and is low in Al2O3 (78.7; 79.2) and high in MgO (3.3; 3.7) and TiO2 (6.5; 7.9) (in wt. %). The oxide CaO is about the same in both varieties. It is suggested that the change in the color of the visible luminescence results from changes in composition. The origin of hibonite which occurs in complex mineral assemblages together with anorthite, gelhenite, wollastonite, aluminous diopside, andradite, Ca-pyroxene, perovskite, spinel, taenite, chromite, and pentlandite, and in close proximity to nodules containing calcite, whewellite, forsterite and many of the aforementioned phases, is discussed. The proposition that hibonite and associated phases originated by contact metamorphism and metasomatism of calcite-dolomite bearing assemblages cannot, at this time, be completely ruled out.

  14. Polymer Coated CaAl-Layered Double Hydroxide Nanomaterials for Potential Calcium Supplement

    PubMed Central

    Kim, Tae-Hyun; Lee, Jeong-A; Choi, Soo-Jin; Oh, Jae-Min

    2014-01-01

    We have successfully prepared layered double hydroxide (LDH) nanomaterials containing calcium and aluminum ions in the framework (CaAl-LDH). The surface of CaAl-LDH was coated with enteric polymer, Eudragit®L 100 in order to protect nanomaterials from fast dissolution under gastric condition of pH 1.2. The X-ray diffraction patterns, Fourier transform infrared spectroscopy, scanning electron and transmission electron microscopy revealed that the pristine LDH was well prepared having hydrocalumite structure, and that the polymer effectively coated the surface of LDH without disturbing structure. From thermal analysis, it was determined that only a small amount (less than 1%) of polymer was coated on the LDH surface. Metal dissolution from LDH nanomaterials was significantly reduced upon Eudragit®L 100 coating at pH 1.2, 6.8 and 7.4, which simulates gastric, enteric and plasma conditions, respectively, and the dissolution effect was the most suppressed at pH 1.2. The LDH nanomaterials did not exhibit any significant cytotoxicity up to 1000 μg/mL and intracellular calcium concentration significantly increased in LDH-treated human intestinal cells. Pharmacokinetic study demonstrated absorption efficiency of Eudragit®L 100 coated LDH following oral administration to rats. Moreover, the LDH nanomaterials did not cause acute toxic effect in vivo. All the results suggest the great potential of CaAl-LDH nanomaterials as a calcium supplement. PMID:25490138

  15. All-sputtered 14% CdS/CdTe thin-film solar cell with ZnO :Al transparent conducting oxide

    NASA Astrophysics Data System (ADS)

    Gupta, Akhlesh; Compaan, Alvin D.

    2004-07-01

    Radio-frequency (rf)-sputtered Al-doped ZnO was used as the transparent front contact in the fabrication of high efficiency superstrate configuration CdS /CdTe thin-film solar cells. These cells had CdS and CdTe layers also deposited by rf sputtering at 250°C with the highest processing temperature of 387°C reached during a post-deposition treatment. The devices were tested at National Renewable Energy Laboratory and yielded an efficiency of 14.0%, which is excellent for a CdTe cell using ZnO and also for any sputtered CdTe solar cell. The low-temperature deposition process using sputtering for all semiconductor layers facilitates the use of ZnO and conveys significant advantages for the fabrication of more complex multiple layers needed for the fabrication of tandem polycrystalline solar cells and for cells on polymer materials.

  16. All-sputtered 14% CdS/CdTe thin-film solar cell with ZnO:Al transparent conducting oxide

    SciTech Connect

    Gupta, Akhlesh; Compaan, Alvin D.

    2004-07-26

    Radio-frequency (rf)-sputtered Al-doped ZnO was used as the transparent front contact in the fabrication of high efficiency superstrate configuration CdS/CdTe thin-film solar cells. These cells had CdS and CdTe layers also deposited by rf sputtering at 250 deg. C with the highest processing temperature of 387 deg. C reached during a post-deposition treatment. The devices were tested at National Renewable Energy Laboratory and yielded an efficiency of 14.0%, which is excellent for a CdTe cell using ZnO and also for any sputtered CdTe solar cell. The low-temperature deposition process using sputtering for all semiconductor layers facilitates the use of ZnO and conveys significant advantages for the fabrication of more complex multiple layers needed for the fabrication of tandem polycrystalline solar cells and for cells on polymer materials.

  17. Reconstructing the Late Pleistocene Southern Ocean biological pump using the vertical gradient of Cd/Ca in planktic and benthic foraminifera

    NASA Astrophysics Data System (ADS)

    Charidemou, Miros; Hall, Ian; Ziegler, Martin

    2015-04-01

    arise due to δ13C fractionation between the ocean and the atmosphere. Due to the similarity in the distribution of phosphate and cadmium (Cd) in the ocean and the incorporation of this trace metal into the calcite tests of foraminifera, Cd/Ca ratios can provide an additional proxy for reconstructing the vertical nutrient distribution in the ocean in the same way as δ13C. We present downcore records of Cd/Ca in the deep-dwelling planktic species, Globorotalia truncatulinoides (s) and the benthic species, Cibicidoides wuellerstorfi from sediment core MD02-2588. A new core a core-top calibration of Cd/Ca in G. truncatulinoides, combined with the established calibration for benthic species allows us to estimate seawater Cd within intermediate and deep water masses that bath the study site and to reconstruct the vertical seawater Cd gradient (ΔCdsw) over the past 150,000 years. Comparison of ΔCdsw to Δδ13C from the same samples from core MD02-2588 in the Southern Ocean indicate a very similar downcore variability which supports the use of the Δδ13C method to reconstruct the biological pump during the MPT.

  18. Complex Formation Between Ca(II), Mg(II), Al(III) Ions and Salicylglycine

    PubMed Central

    Kilyén, Melinda; Labádi, lmre; Tombácz, Etelka; Kiss, Tamás

    2003-01-01

    For modelling the interactions of proteins/peptides with hard metal ions the complex formation of salicylglycine (SalGly) with Ca(II), Mg(ll) and AI(III) ions was studied in aqueous solution using pHpotentiometric and UV-vis spectroscopic techniques. Al(lll) ion was found to form more stable complexes with SalGiy than Ca(ll) or Mg(ll) ions. While AI(III) ion forms various 1:1 complexes of different protonation states in the pH range 2-7, Ca(ll), Mg(ll) ions seem to interact with SalGly only in the basic pH range and form mixed hydroxo species MLH-1 at pH ~ 8. According to the UV-vis spectroscopic measurements in the species MLH-1 the carboxylate-O- atom and the phenolate-O- coordinate to the metal ions. SaIGiy is able to keep Al(lll) in solution through inner and outer sphere coordination to metastable amorphous AI(OH)3 particles. Deprotonation of the peptide amide Nil does not occur in these systems. PMID:18365063

  19. Network topology for the formation of solvated electrons in binary CaO-Al2O3 composition glasses.

    PubMed

    Akola, Jaakko; Kohara, Shinji; Ohara, Koji; Fujiwara, Akihiko; Watanabe, Yasuhiro; Masuno, Atsunobu; Usuki, Takeshi; Kubo, Takashi; Nakahira, Atsushi; Nitta, Kiyofumi; Uruga, Tomoya; Weber, J K Richard; Benmore, Chris J

    2013-06-18

    Glass formation in the CaO-Al2O3 system represents an important phenomenon because it does not contain typical network-forming cations. We have produced structural models of CaO-Al2O3 glasses using combined density functional theory-reverse Monte Carlo simulations and obtained structures that reproduce experiments (X-ray and neutron diffraction, extended X-ray absorption fine structure) and result in cohesive energies close to the crystalline ground states. The O-Ca and O-Al coordination numbers are similar in the eutectic 64 mol % CaO (64CaO) glass [comparable to 12CaO·7Al2O3 (C12A7)], and the glass structure comprises a topologically disordered cage network with large-sized rings. This topologically disordered network is the signature of the high glass-forming ability of 64CaO glass and high viscosity in the melt. Analysis of the electronic structure reveals that the atomic charges for Al are comparable to those for Ca, and the bond strength of Al-O is stronger than that of Ca-O, indicating that oxygen is more weakly bound by cations in CaO-rich glass. The analysis shows that the lowest unoccupied molecular orbitals occurs in cavity sites, suggesting that the C12A7 electride glass [Kim SW, Shimoyama T, Hosono H (2011) Science 333(6038):71-74] synthesized from a strongly reduced high-temperature melt can host solvated electrons and bipolarons. Calculations of 64CaO glass structures with few subtracted oxygen atoms (additional electrons) confirm this observation. The comparable atomic charges and coordination of the cations promote more efficient elemental mixing, and this is the origin of the extended cage structure and hosted solvated (trapped) electrons in the C12A7 glass.

  20. Nanostructured Al-ZnO/CdSe/Cu2O ETA solar cells on Al-ZnO film/quartz glass templates

    NASA Astrophysics Data System (ADS)

    Wang, Xianghu; Li, Rongbin; Fan, Donghua

    2011-12-01

    The quartz/Al-ZnO film/nanostructured Al-ZnO/CdSe/Cu2O extremely thin absorber solar cell has been successfully realized. The Al-doped ZnO one-dimensional nanostructures on quartz templates covered by a sputtering Al-doped ZnO film was used as the n-type electrode. A 19- to 35-nm-thin layer of CdSe absorber was deposited by radio frequency magnetron sputtering, coating the ZnO nanostructures. The voids between the Al-ZnO/CdSe nanostructures were filled with p-type Cu2O, and therefore, the entire assembly formed a p-i-n junction. The cell shows the energy conversion efficiency as high as 3.16%, which is an interesting option for developing new solar cell devices. PACS: 88.40.jp; 73.40.Lq; 73.50.Pz.

  1. Nanostructured Al-ZnO/CdSe/Cu2O ETA solar cells on Al-ZnO film/quartz glass templates.

    PubMed

    Wang, Xianghu; Li, Rongbin; Fan, Donghua

    2011-01-01

    The quartz/Al-ZnO film/nanostructured Al-ZnO/CdSe/Cu2O extremely thin absorber solar cell has been successfully realized. The Al-doped ZnO one-dimensional nanostructures on quartz templates covered by a sputtering Al-doped ZnO film was used as the n-type electrode. A 19- to 35-nm-thin layer of CdSe absorber was deposited by radio frequency magnetron sputtering, coating the ZnO nanostructures. The voids between the Al-ZnO/CdSe nanostructures were filled with p-type Cu2O, and therefore, the entire assembly formed a p-i-n junction. The cell shows the energy conversion efficiency as high as 3.16%, which is an interesting option for developing new solar cell devices.PACS: 88.40.jp; 73.40.Lq; 73.50.Pz. PMID:22136081

  2. Cd(2+) sensitivity and permeability of a low voltage-activated Ca(2+) channel with CatSper-like selectivity filter.

    PubMed

    Garza-López, Edgar; Chávez, Julio César; Santana-Calvo, Carmen; López-González, Ignacio; Nishigaki, Takuya

    2016-07-01

    CatSper is a sperm-specific Ca(2+) channel that plays an essential role in the male fertility. However, its biophysical properties have been poorly characterized mainly due to its deficient heterologous expression. As other voltage-gated Ca(2+) channels (CaVs), CatSper possesses a conserved Ca(2+)-selective filter motif ([T/S]x[D/E]xW) in the pore region. Interestingly, CatSper conserves four aspartic acids (DDDD) as the negatively charged residues in this motif while high voltage-activated CaVs have four glutamic acids (EEEE) and low voltage-activated CaVs possess two glutamic acids and two aspartic acids (EEDD). Previous studies based on site-directed mutagenesis of L- and T-type channels showed that the number of D seems to have a negative correlation with their cadmium (Cd(2+)) sensitivity. These results suggest that CatSper (DDDD) would have low sensitivity to Cd(2+). To explore Cd(2+)-sensitivity and -permeability of CatSper, we performed two types of experiments: 1) Electrophysiological analysis of heterologously expressed human CaV3.1 channel and three pore mutants (DEDD, EDDD and DDDD), 2) Cd(2+) imaging of human spermatozoa with FluoZin-1. Electrophysiological studies showed a significant increase in Cd(2+) and manganese (Mn(2+)) currents through the CaV3.1 mutants as well as a reduction in the inhibitory effect of Cd(2+) on the Ca(2+) current. In fluorescence imaging with human sperm, we observed an increase in Cd(2+) influx potentiated by progesterone, a potent activator of CatSper. These results support our hypothesis, namely that Cd(2+)-sensitivity and -permeability are related to the absolute number of D in the Ca(2+)-selective filter independently to the type of the Cav channels.

  3. Low-temperature heat capacities of CaAl2SiO6 glass and pyroxene and thermal expansion of CaAl2SiO6 pyroxene.

    USGS Publications Warehouse

    Haselton, H.T.; Hemingway, B.S.; Robie, R.A.

    1984-01-01

    Low-T heat capacities (5-380 K) have been measured by adiabatic calorimetry for synthetic CaAl2SiO6 glass and pyroxene. High-T unit cell parameters were measured for CaAl2SiO6 pyroxene by means of a Nonius Guinier-Lenne powder camera in order to determine the mean coefficient of thermal expansion in the T range 25-1200oC. -J.A.Z.

  4. Nqrs Data for AlCa2ClH10O8 [AlCa2ClO3·5(H2O)] (Subst. No. 0020)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for AlCa2ClH10O8 [AlCa2ClO3·5(H2O)] (Subst. No. 0020)

  5. Surface micromorphology of dental composites [CE-TZP]-[Al2O3] with Ca(+2) modifier.

    PubMed

    Berezina, Sofia; Il'icheva, Alla Alexandrovna; Podzorova, Lyudmila Ivanovna; Ţălu, Ştefan

    2015-09-01

    The objective of this study was to characterize the three-dimensional (3D) surface micromorphology of the ceramics produced from nanoparticles of alumina and tetragonal zirconia (t-ZrO2) with addition of Ca(+2) for sintering improvement. The 3D surface roughness of samples was studied by atomic force microscopy (AFM), fractal analysis of the 3D AFM-images, and statistical analysis of surface roughness parameters. Cube counting method, based on the linear interpolation type, applied for AFM data was used for fractal analysis. The morphology of non-modified ceramic sample was characterized by the rather big (1-2 μm) grains of α-Al2O3 phase with a habit close to hexagonal drowned in solid solution of t-ZrO2 with smooth surface. The pattern surfaces of modified composite content a little amount of elongated prismatic grains with composition close to the phase of СаСеAl3О7 as well as hexahedral α-Al2O3-grains. Fractal dimension, D, as well as height values distribution have been determined for the surfaces of the samples with and without modifying. It can be concluded that the smoothest surface is of the modified samples with Ca(+2) modifier but the most regular one is of the non-modified samples. A connection was observed between the surface morphology and the physical properties as assessed in previous works. PMID:26190812

  6. CaMn2Al10: Itinerant Mn magnetism on the verge of magnetic order

    DOE PAGES

    Steinke, L.; Simonson, J. W.; Yin, W. -G.; Smith, G. J.; Kistner-Morris, J. J.; Zellman, S.; Puri, A.; Aronson, M. C.

    2015-07-24

    We report the discovery of CaMn2Al10, a metal with strong magnetic anisotropy and moderate electronic correlations. Magnetization measurements find a Curie-Weiss moment of 0.83μB/Mn, significantly reduced from the Hund's rule value, and the magnetic entropy obtained from specific heat measurements is correspondingly small, only ≈ 9% of Rln2. These results imply that the Mn magnetism is highly itinerant, a conclusion supported by density functional theory calculations that find strong Mn-Al hybridization. Consistent with the layered nature of the crystal structure, the magnetic susceptibility χ is anisotropic below 20 K, with a maximum ratio of χ[010]/χ[001] ≈ 3.5. A strong power-lawmore » divergence χ(T) ~ T–1.2 below 20 K implies incipient ferromagnetic order, an Arrott plot analysis of the magnetization suggests a vanishing low Curie temperature TC ~ 0. Our experiments indicate that CaMn2Al10 is a rare example of a system where the weak and itinerant Mn-based magnetism is poised on the verge of order.« less

  7. Chemical zoning and diffusion of Ca, Al, Mn, and Cr in olivine of springwater pallasite

    NASA Technical Reports Server (NTRS)

    Zhou, Y.; Steele, Ian M.

    1993-01-01

    The pallasites, consisting mainly of Fe-Ni metal and olivine, are thought to represent the interior of a planetary body which slowly cooled from high temperature. Although the olivines are nearly homogeneous, ion microprobe studies revealed variations of Ca, Ti, Co, Cr, and Ni near grain edges. These variations were thought to represent diffusion in response to falling temperature of the parent body. Pallasite cooling rates have been estimated based on kamacite taenite textures but results differ by x100. In principle elemental profiles in olivine can allow estimates of cooling rate if diffusion coefficients are known; in addition, given a cooling rate, diffusion coefficients could be derived. Data are presented which show that apparent diffusion profiles can be measured for Al, Ca, Cr, and Mn which qualitatively agree with expected diffusion rates and have the potential of providing independent estimates of pallasite cooling rates.

  8. Dielectric properties of CaNdAlO sub 4 at microwave frequencies

    SciTech Connect

    Konopka, J.; Wolff, I. ); Lewandowski, S.J. )

    1992-07-01

    Dielectric properties of CaNdAlO{sub 4} monocrystals, a prospective substrate material for the deposition of high-{ital T}{sub {ital c}} superconductors, were measured with high accuracy at microwave frequencies from 8 to 40 GHz in the temperature range from 10 to 300 K by measuring the resonant frequencies of a completely filled resonant cavity. The material was found to be highly anisotropic. At 300 K it exhibits the dielectric constant along {ital c} axis {epsilon}{sup {prime}}{sub {ital c}} = 17.68, while the dielectric constant in the {ital a}-{ital b} plane is {epsilon}{prime}=19.62, and loss tangent tan {delta}{sub {ital c}} {congruent} tan {delta} {congruent} 5.1{times} 10{sup {minus}4}. Both {epsilon}{sup {prime}}{sub {ital c}} and {epsilon}{prime} depend strongly on temperature and their thermal coefficients have opposite signs, apparently a unique property of CaNdAlO{sub 4}. Below 160 K microwave losses caused by electric field perpendicular to the optical {ital c} axis increase with decreasing temperature, exhibiting a maximum near 65 K followed by a minimum at 30 K. It is suggested that neodymium ions in CaNdAlO{sub 4} at lower temperatures become magnetically ordered, causing an increase of magnetic permeability {mu}{sup {prime}}{sub {ital c}} {gt} 1 and a significant increase of magnetic losses at microwave frequencies. A crystallographic phase transition below 60 K cannot also be excluded.

  9. Magnetic behaviour of the MTbF{sub 6} fluoroterbates (M=Cd, Ca, Sr, ({alpha}/{beta})-Ba)

    SciTech Connect

    Josse, M.; El-Ghozzi, M.; Avignant, D.; Andre, G.; Bouree, F.; Isnard, O.

    2012-01-15

    Neutron powder diffraction has been performed on the MTbF{sub 6} fluorides (M=Cd, Ca, Sr, ({alpha}/{beta})-Ba). Four of these fluorides (Cd, Ca, Sr, {beta}-Ba) are built of a (pseudo-) tetragonal packing of [TbF{sub 6}]{sup 2-} chains and only differs by the chains relative orientations. Thus this series represents a valuable opportunity to evaluate the Tb{sup 4+}-Tb{sup 4+} magnetic interactions. All the compounds displayed antiferromagnetic order (T{sub N}=2.70 K (Cd), 2.15 K (Ca), 2.60 K (Sr), 2.10 K ({beta}-Ba)), except for the {alpha} form of BaTbF{sub 6}. The crystal structure of this latter fluoroterbate has also been investigated by means of high-resolution neutron powder diffraction. From Neutron Powder Diffraction data, CdTbF{sub 6} and {beta}-BaTbF{sub 6} magnetic structures were determined, together with the metamagnetic behaviour of {beta}-BaTbF{sub 6} as a function of an external magnetic field. A tentative phase diagram is then given for {beta}-BaTbF{sub 6}. Advantage was taken of the polymorphism of the BaTbF{sub 6} fluoroterbate to analyse, on the basis of topological parameters such as bond distances and angles, the magnetic behaviour of its {alpha} and {beta} forms. It was shown that superexchange interactions are present in {beta}-BaTbF{sub 6}, and that these interactions may also rule the magnetic behaviour of the other MTbF{sub 6} (M=Ca, Sr, Cd) tetravalent terbium fluorides. - Graphical abstract: Powder neutron diffraction revealed magnetic order in four of the five investigated fluoroterbates, while crystal chemical analyses of {alpha} and {beta} forms of BaTbF{sub 6} evidenced the existence of superexchange interactions. Highlights: Black-Right-Pointing-Pointer Five fluoroterbates are investigated by Powder Neutron Diffraction (PND). Black-Right-Pointing-Pointer Four of them are antiferromagnetically ordered at 1.4 K. Black-Right-Pointing-Pointer Magnetic structures of {beta}-BaTbF{sub 6} and CdTbF{sub 6} are determined. Black

  10. Disarrangement of actin filaments and Ca²⁺ gradient by CdCl₂ alters cell wall construction in Arabidopsis thaliana root hairs by inhibiting vesicular trafficking.

    PubMed

    Fan, Jun-Ling; Wei, Xue-Zhi; Wan, Li-Chuan; Zhang, Ling-Yun; Zhao, Xue-Qin; Liu, Wei-Zhong; Hao, Huai-Qin; Zhang, Hai-Yan

    2011-07-15

    Cadmium (Cd), one of the most toxic heavy metals, inhibits many cellular and physiological processes in plants. Here, the involvement of cytoplasmic Ca²⁺ gradient and actin filaments (AFs) in vesicular trafficking, cell wall deposition and tip growth was investigated during root (hair) development of Arabidopsis thaliana in response to CdCl₂ treatment. Seed germination and root elongation were prevented in a dose- and time-dependent manner by CdCl₂ treatment. Fluorescence labelling and non-invasive detection showed that CdCl₂ inhibited extracellular Ca²⁺ influx, promoted intracellular Ca²⁺ efflux, and disturbed the cytoplasmic tip-focused Ca²⁺ gradient. In vivo labelling revealed that CdCl₂ modified actin organization, which subsequently contributed to vesicle trafficking. Transmission electron microscopy revealed that CdCl₂ induced cytoplasmic vacuolization and was detrimental to organelles such as mitochondria and endoplasmic reticulum (ER). Finally, immunofluorescent labelling and Fourier transform infrared (FTIR) analysis indicated that configuration/distribution of cell wall components such as pectins and cellulose was significantly altered in response to CdCl₂. Our results indicate that CdCl₂ induces disruption of Ca²⁺ gradient and AFs affects the distribution of cell wall components in root hairs by disturbing vesicular trafficking in A. thaliana.

  11. Partition coefficients for Al, Ca, Ti, Cr, and Ni in olivine obtained by melting experiment on an LL6 chondrite

    NASA Technical Reports Server (NTRS)

    Miyamoto, M.; Mikouchi, T.; Mckay, G. A.

    1994-01-01

    We report the partition coefficients for Ca, Al, Ti, Cr, and Ni in olivine obtained through a series of melting experiments on an LL6 chondrite under varying conditions of temperature and oxygen fugacity. It is necessary to examine the variation of partition coefficients up to extremely reducing conditions in order to study meteoritic olivines. For Ca, Al, and Cr, the partition coefficients tend to decrease as temperature increases, but do not change even under extremely reducing conditions.

  12. Acid precipitation and food quality: Effects of dietary Al, Ca and P on bone and liver characteristics in American black ducks and mallards

    USGS Publications Warehouse

    Sparling, D.W.

    1991-01-01

    American black ducks (Anas rubripes) and mallards (A. platyrhynchos) were fed diets varying in concentrations of aluminum (Al). calcium (Ca), and phosphorus (P) for 10 weeks to identify toxic effects of Al under conditions representative of areas with acid precipitation. Femur and liver tissues were analyzed for Al. Ca, and P concentrations and structural characteristics. At two weeks of age, both species demonstrated pronounced differences in femur Al and P concentrations and femur mass from dietary Al and interaction between Ca:P regimen and Al:Low Ca:Low P enhanced Al storage and decreased P and mass in femurs. Femur Ca was lowest in the Low Ca:Low P regimen but was not affected by dietary Al. At 10 weeks, femur and liver Al continued to vary with dietary Al. Elevated Al and reduced Ca lowered modulus of elasticity. Femur P increased with elevated dietary P in black ducks. Elevated dietary P negated some of the effects of dietary A! on femur mass in black ducks. Reduced Ca concentrations weakened bones of both species and lowered both Ca and P. An array of clinical signs including lameness, discoloration of the upper mandible, complete and greenstick fractures, and death were responses to elevated Al and Ca:P regimen. Black ducks seemed to display these signs over a wider range of diets than mallards. Diets of 1,000 mg/kg Al had toxic effects on both species, particularly when combined with diets low in Ca and P.

  13. Biochemical responses of the mycorrhizae in Pinus massoniana to combined effects of Al, Ca and low pH.

    PubMed

    Kong, F X; Liu, Y; Hu, W; Shen, P P; Zhou, C L; Wang, L S

    2000-02-01

    Biochemical responses of Pinus massoniana, with and without the inoculation mycorrhizal fungus Pisolithus tinctorius at the root, to artificial acid rain (pH 2.0) and various Ca/Al ratios were investigated. Some enzymes associated with the nutritive metabolism, such as acid phosphatase, alkaline phosphatase, nitrate reductase, mannitol dehydrogenase and trehalase, in the roots, stems and leaves of plant were obviously inhibited by the artificial acid rain and Al. After treatment with pH 2.0 + Ca/Al (0/1 or 1/10) artificial acid rain, the protein content in the organs was decreased. However, the activities of superoxide dismutase (SOD) and peroxidase (POD) and glutathione (GSH) concentrations were induced. It demonstrated that acid rain and Al could induce oxygen radicals in plant. Compared with the treatments with lower pH or Al, respectively, the combination of lower pH and Al concentration was more toxic to P. massoniana. Al toxicity could be ameliorated by the addition of Ca and the amelioration was the most when the ratio was 1/1 among the various Ca/Al ratio. Infection with mycorrhizal fungus P. tinctorius at the root of P. massoniana increased the ability of the plant to resist the toxicity of artificial acid rain and Al stress.

  14. Network topology for the formation of solvated electrons in binary CaO–Al2O3 composition glasses

    PubMed Central

    Akola, Jaakko; Kohara, Shinji; Ohara, Koji; Fujiwara, Akihiko; Watanabe, Yasuhiro; Masuno, Atsunobu; Usuki, Takeshi; Kubo, Takashi; Nakahira, Atsushi; Nitta, Kiyofumi; Uruga, Tomoya; Weber, J. K. Richard; Benmore, Chris J.

    2013-01-01

    Glass formation in the CaO–Al2O3 system represents an important phenomenon because it does not contain typical network-forming cations. We have produced structural models of CaO–Al2O3 glasses using combined density functional theory–reverse Monte Carlo simulations and obtained structures that reproduce experiments (X-ray and neutron diffraction, extended X-ray absorption fine structure) and result in cohesive energies close to the crystalline ground states. The O–Ca and O–Al coordination numbers are similar in the eutectic 64 mol % CaO (64CaO) glass [comparable to 12CaO·7Al2O3 (C12A7)], and the glass structure comprises a topologically disordered cage network with large-sized rings. This topologically disordered network is the signature of the high glass-forming ability of 64CaO glass and high viscosity in the melt. Analysis of the electronic structure reveals that the atomic charges for Al are comparable to those for Ca, and the bond strength of Al–O is stronger than that of Ca–O, indicating that oxygen is more weakly bound by cations in CaO-rich glass. The analysis shows that the lowest unoccupied molecular orbitals occurs in cavity sites, suggesting that the C12A7 electride glass [Kim SW, Shimoyama T, Hosono H (2011) Science 333(6038):71–74] synthesized from a strongly reduced high-temperature melt can host solvated electrons and bipolarons. Calculations of 64CaO glass structures with few subtracted oxygen atoms (additional electrons) confirm this observation. The comparable atomic charges and coordination of the cations promote more efficient elemental mixing, and this is the origin of the extended cage structure and hosted solvated (trapped) electrons in the C12A7 glass. PMID:23723350

  15. Diagnostic performance of CD66c in lung adenocarcinoma-associated malignant pleural effusion: comparison with CEA, CA 19-9, and CYFRA 21-1.

    PubMed

    Son, Seung-Myoung; Han, Hye-Suk; An, Jin Young; Choe, Kang Hyeon; Lee, Ki Man; Lee, Ki Hyeong; Kim, So-Seul; Lee, Yong-Moon; Lee, Ho-Chang; Song, Hyung Geun; Lee, Ok-Jun

    2015-02-01

    Various tumour markers have been evaluated in malignant pleural effusions, but not CD66c. This study evaluated the diagnostic ability of CD66c in lung adenocarcinoma-associated malignant pleural effusions (LA-MPEs) and compared it with other known tumour markers. Forty-seven cases of LA-MPE and 52 cases of benign pleural effusions were collected. The levels of CD66c, CEA, CA 19-9, and CYFRA 21-1 were measured by enzyme immunoassay. The expression of CD66c, CEA, and CA 19-9 in cell blocks was measured by immunocytochemistry. CEA had the best diagnostic values, with a sensitivity of 87.2% and specificity of 92.3%. Both CD66c and CA 19-9 showed the highest specificity of 98.1%, with sensitivities of 63.8% and 55.3%, respectively. CYFRA 21-1 had a sensitivity of 83.0% and specificity of 76.9%. CEA combined with CA 19-9 reached a sensitivity of 91.5% and a specificity of 98.1%. The sensitivities of immunocytochemical staining for CD66c, CEA, and CA 19-9 were 72.5%, 75%, and 40%, respectively. CD66c showed a diagnostic performance comparable to CYFRA 21-1 and CA 19-9 by enzyme immunoassay. Immunocytochemical study showed that CD66c and CEA were more sensitive than CA19-9. Both studies support CD66c as a potential tumour marker to differentiate LA-MPE from benign effusions. PMID:25551300

  16. Diagnostic performance of CD66c in lung adenocarcinoma-associated malignant pleural effusion: comparison with CEA, CA 19-9, and CYFRA 21-1.

    PubMed

    Son, Seung-Myoung; Han, Hye-Suk; An, Jin Young; Choe, Kang Hyeon; Lee, Ki Man; Lee, Ki Hyeong; Kim, So-Seul; Lee, Yong-Moon; Lee, Ho-Chang; Song, Hyung Geun; Lee, Ok-Jun

    2015-02-01

    Various tumour markers have been evaluated in malignant pleural effusions, but not CD66c. This study evaluated the diagnostic ability of CD66c in lung adenocarcinoma-associated malignant pleural effusions (LA-MPEs) and compared it with other known tumour markers. Forty-seven cases of LA-MPE and 52 cases of benign pleural effusions were collected. The levels of CD66c, CEA, CA 19-9, and CYFRA 21-1 were measured by enzyme immunoassay. The expression of CD66c, CEA, and CA 19-9 in cell blocks was measured by immunocytochemistry. CEA had the best diagnostic values, with a sensitivity of 87.2% and specificity of 92.3%. Both CD66c and CA 19-9 showed the highest specificity of 98.1%, with sensitivities of 63.8% and 55.3%, respectively. CYFRA 21-1 had a sensitivity of 83.0% and specificity of 76.9%. CEA combined with CA 19-9 reached a sensitivity of 91.5% and a specificity of 98.1%. The sensitivities of immunocytochemical staining for CD66c, CEA, and CA 19-9 were 72.5%, 75%, and 40%, respectively. CD66c showed a diagnostic performance comparable to CYFRA 21-1 and CA 19-9 by enzyme immunoassay. Immunocytochemical study showed that CD66c and CEA were more sensitive than CA19-9. Both studies support CD66c as a potential tumour marker to differentiate LA-MPE from benign effusions.

  17. Influence of Ca and pH on the uptake and effects of Cd in Folsomia candida exposed to simplified soil solutions.

    PubMed

    Ardestani, Masoud M; Ortiz, Maria Diez; van Gestel, Cornelis A M

    2013-08-01

    The present study sought to quantify the components of a biotic ligand model (BLM) for the effects of Cd on Folsomia candida (Collembola). Assuming that soil porewater is the main route of exposure and to exclude the effects of soil particles on metal availability, animals were exposed for 7 d to different Cd concentrations between 0.1 mM and 100 mM in simplified soil solutions at different Ca concentrations (0.2 mM, 0.8 mM, 3.2 mM, and 12.8 mM) or at different pH (5.0, 6.0, and 7.0). Higher Ca concentrations decreased the toxicity of Cd (adult survival) in test solutions, whereas toxicity was slightly lower at pH 7 and 6 than at pH 5, suggesting a mitigating effect of Ca and to a lesser extent pH on Cd toxicity to F. candida. Internal Cd concentrations in the animals increased with increasing exposure level but were significantly reduced by increasing Ca concentrations and were not significantly affected by pH. By using Langmuir isotherms, binding constants for Cd, Ca, and protons and the fraction of binding sites occupied by Cd were calculated and used to predict effects of Cd on survival. Predicted toxicity showed a good agreement with measured responses when Ca and pH were used as separate factors or combined together. The present study shows indications of protective effects of Ca but less of protons on the toxicity and uptake of Cd in F. candida on exposure to simplified soil solutions, which can be described using the principles of a biotic ligand model.

  18. Dissolution Behavior of Indium in CaO-SiO2-Al2O3 Slag

    NASA Astrophysics Data System (ADS)

    Ko, Kyu Yeol; Park, Joo Hyun

    2011-12-01

    The solubility of indium in a molten CaO-SiO2-Al2O3 system was measured at 1773 K (1500 °C) to establish the dissolution mechanism of indium under a highly reducing atmosphere. The solubility of indium increases with increasing oxygen potential, whereas it decreases with increased activity of basic oxide. Therefore, a dissolution mechanism of indium can be constructed according to the following equation: {{In}}({{s}}) + 1/4{{O}}2 ({{g}}) = ({{In}}^{ + } ) + 1/2({{O}}^{2 - } ) The relationship between indium capacity and sulfide capacity shows a good correlation that is consistent with theoretical expectations. The enthalpy change of the indium dissolution reaction is negative, which indicates that the dissolution is an exothermic reaction. The heat of dissolution into high-silica melts is greater than that into low-silica melts. The solubility of indium is strongly dependent on the silica content. The activity coefficient, and thus the excess free energy of In2O, decreases linearly with increasing silica content, indicating that the In2O is believed to behave as a weak basic oxide in the current CaO-SiO2-Al2O3 ternary system under reducing conditions.

  19. Magnesium doping on brownmillerite Ca{sub 2}FeAlO{sub 5}

    SciTech Connect

    Malveiro, J.; Ramos, T.; Ferreira, L.P.; Waerenborgh, J.C.

    2007-06-15

    Ca{sub 2}FeAl{sub 1-} {sub x} Mg {sub x} O{sub 5} (x=0, 0.05 and 0.1) compounds adopting the brownmillerite-type structure were prepared by a self-combustion route using two different fuels. Characterisation was performed using X-ray powder diffraction, Moessbauer spectroscopy, magnetisation measurements, chemical analysis, scanning electron microscopy and 4-point dc conductivity measurements. Global results indicate that the solubility limit was reached for x=0.1. An antiferromagnetic behaviour was detected for all studied compositions, with magnetic ordering temperatures of 340 and 290 K for x=0 and 0.05, respectively. Mg doping increases the number of iron cations in tetrahedral sites, which induces magnetisation enhancement at low temperatures through the coupling between octahedral iron cations in different octahedral planes. The compounds exhibit semiconductor behaviour and Mg{sup 2+} doping yields a significant enhancement of the total conductivity, which can be essentially attributed to the presence of Fe{sup 4+} ions. - Graphical abstract: Ca{sub 2}FeAl{sub 1-} {sub x} Mg {sub x} O{sub 5} (x=0, 0.05, 0.1) compounds with the brownmillerite structure were prepared and characterised. The paramagnetic Moessbauer spectra presented were obtained at T=363 K (x=0); T=297 K (x=0.05) and T=353 K (x=0.1)

  20. CD36- and GPR120-mediated Ca2+ Signaling in Human Taste Bud Cells Mediates Differential Responses to Fatty Acids and is Altered in Obese Mice

    PubMed Central

    Ozdener, Mehmet Hakan; Subramaniam, Selvakumar; Sundaresan, Sinju; Sery, Omar; Hashimoto, Toshihiro; Asakawa, Yoshinori; Besnard, Philippe; Abumrad, Nada A.; Khan, Naim Akhtar

    2014-01-01

    Background & Aims It is important to increase our understanding of gustatory detection of dietary fat and its contribution to fat preference. We studied the roles of the fat taste receptors CD36 and GPR120 and their interactions via Ca2+ signaling in fungiform taste bud cells (TBC). Methods We measured Ca2+ signaling in human TBC, transfected with small interfering RNAs (siRNAs) against mRNAs encoding CD36 and GPR120 (or control siRNAs). We also studied Ca2+ signaling in TBC from CD36−/− mice and from wild-type lean and obese mice. Additional studies were conducted with mouse enteroendocrine cell line STC-1 that express GPR120 and stably transfected with human CD36. We measured release of serotonin and GLP-1 from human and mice TBC in response to CD36 and GPR120 activation. Results High concentrations of linoleic acid induced Ca2+ signaling via CD36 and GPR120 in human and mice TBC as well as in STC-1 cells, whereas low concentrations induced Ca2+ signaling via only CD36. Incubation of human and mice fungiform TBC with lineoleic acid downregulated CD36 and upregulated GPR120 in membrane lipid rafts. Obese mice had decreased spontaneous preference for fat. Fungiform TBC from obese mice had reduced Ca2+ and serotonin responses but increased release of GLP1, along with reduced levels of CD36 and increased levels of GPR120 in lipid rafts. Conclusions CD36 and GPR120 have non-overlapping roles in TBC signaling during oro-gustatory perception of dietary lipids; these are differentially regulated by obesity. PMID:24412488

  1. Self-reactivated mesostructured Ca-Al-O composite for enhanced high-temperature CO2 capture and carbonation/calcination cycles performance.

    PubMed

    Chang, Po-Hsueh; Huang, Wei-Chen; Lee, Tai-Jung; Chang, Yen-Po; Chen, San-Yuan

    2015-03-25

    In this study, highly efficient high-temperature CO2 sorbents of calcium aluminate (Ca-Al-O) mesostructured composite were synthesized using presynthesized mesoporous alumina (MA) as a porous matrix to react with calcium nitrate through a microwave-assisted process. Upon annealing at 600 °C, a highly stable mesoporous structure composed of poorly crystalline Ca12Al14O33 phase and the CaO matrix was obtained. The Ca-Al-O mesostructured sorbents with a Ca(2+)/Al(3+) ratio of 5:1 exhibit an enhanced increasing CO2 absorption kinetics in the CO2 capture capacity from 37.2 wt % to 48.3 wt % without apparent degradation with increasing carbonation/calcination cycling up to 50 at 700 °C due to the strong self-reactivation effect of the mesoporous Ca-Al-O microstructure. Remarkable improvements in the CaO-CaCO3 conversion attained from the mesostructured Ca-Al-O composite can be explained using the concept combined with available mesoporous structure and Ca12Al14O33 phase content. However, a high Ca(2+)/Al(3+) =8:1 Ca-Al-O composite causes degradation because the pores become blocked and partial sintering induces CaO agglomeration. PMID:25730384

  2. Atomistic and Ab initio modeling of CaAl2O4 high-pressure polymorphs under Earth's mantle conditions

    NASA Astrophysics Data System (ADS)

    Eremin, N. N.; Grechanovsky, A. E.; Marchenko, E. I.

    2016-05-01

    Semi-empirical and ab initio theoretical investigation of crystal structure geometry, interatomic distances, phase densities and elastic properties for some CaAl2O4 phases under pressures up to 200 GPa was performed. Two independent simulation methods predicted the appearance of a still unknown super-dense CaAl2O4 modification. In this structure, the Al coordination polyhedron might be described as distorted one with seven vertices. Ca atoms were situated inside polyhedra with ten vertices and Ca-O distances from 1.96 to 2.49 Å. It became the densest modification under pressures of 170 GPa (density functional theory prediction) or 150 GPa (semi-empirical prediction). Both approaches indicated that this super-dense CaAl2O4 modification with a "stuffed α-PbO2" type structure could be a probable candidate for mutual accumulation of Ca and Al in the lower mantle. The existence of this phase can be verified experimentally using high pressure techniques.

  3. Major soil element (Ca, Mg, K, Na, Al, Fe) distribution along the Qinghai-Tibet Railway

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Zhang, Y.; Zhang, H.; Ding, M.; Lin, X.

    2011-12-01

    The Tibetan Plateau (TP), which has been called the third polar region, is the highest plateau in the world. There are a series of special soils present in the TP, which are extremely important in soil sciences for their particularities. Soil chemical composition is one of the necessary indices of soil characteristics. The major element content of the soil, such as Ca, Mg, K, Na, not only can affect the soil pH value and soil fertility but also are the main drivers of soil geochemical processes. It is helpful to understand the TP environmental characteristics, to study the major soil element content.The Qinghai-Tibet Railway (QTR) is the highest-elevation and the longest highland railway on earth. There are nearly all types of TP soil along the QTR. Most of the areas along the QTR are in fairly pristine condition. This offers a good platform to study the natural environmental characteristics of the soil. This study selected 240 soil samples from 28 sample areas along the Qinghai-Tibet Railway, and the aluminum, iron, calcium, sodium, potassium and magnesium content in the soil were measured with ICP-AES. The results indicated: (1) Compared with the national soil background values, the Ca content in soil was higher along the QTR and Al was lower; but the Fe, Mg, K and Na contents were similar. (2) Along the whole QTR, the soil Al, Fe and Mg content showed a decreasing trend from Xining to Lhasa, the changes in K and Na values were relatively complex, and the distribution of Ca could be divided three sections. (3) The soil element contents varied with different soil types and parent materials. Most of the six elements content was minimum in soil, which derived from debris materials for ice and water, and the elements content was maximum in soil, which evolved from debris for flood, and the content of soil Ca developed from debris for lake was maximum. The amount of each element present in the Hapli-Cryic Aridosols and Calci-Cryic Aridosols was relatively higher than

  4. Simultaneous determination of Ca, Cu, Ni, Zn and Cd binding strengths with fulvic acid fractions by Schubert's method

    USGS Publications Warehouse

    Brown, G.K.; MacCarthy, P.; Leenheer, J.A.

    1999-01-01

    The equilibrium binding of Ca2+, Ni2+, Cd2+, Cu2+ and Zn2+ with unfractionated Suwannee river fulvic acid (SRFA) and an enhanced metal binding subfraction of SRFA was measured using Schubert's ion-exchange method at pH 6.0 and at an ionic strength (??) of 0.1 (NaNO3). The fractionation and subfractionation were directed towards obtaining an isolate with an elevated metal binding capacity or binding strength as estimated by Cu2+ potentiometry (ISE). Fractions were obtained by stepwise eluting an XAD-8 column loaded with SRFA with water eluents of pH 1.0 to pH 12.0. Subfractions were obtained by loading the fraction eluted from XAD-8 at pH 5.0 onto a silica gel column and eluting with solvents of increasing polarity. Schuberts ion exchange method was rigorously tested by measuring simultaneously the conditional stability constants (K) of citric acid complexed with the five metals at pH 3.5 and 6.0. The logK of SRFA with Ca2+, Ni2+, Cd2+, Cu2+ and Zn2+ determined simultaneously at pH 6.0 follow the sequence of Cu2+>Cd2+>Ni2+>Zn2+>Ca2+ while all logK values increased for the enhanced metal binding subfraction and followed a different sequence of Cu2+>Cd2+>Ca2+>Ni2+>Zn2+. Both fulvic acid samples and citric acid exhibited a 1:1 metal to ligand stochiometry under the relatively low metal loading conditions used here. Quantitative 13C nuclear magnetic resonance spectroscopy showed increases in aromaticity and ketone content and decreases in aliphatic carbon for the elevated metal binding fraction while the carboxyl carbon, and elemental nitrogen, phosphorus, and sulfur content did not change. The more polar, elevated metal binding fraction did show a significant increase in molecular weight over the unfractionated SRFA. Copyright (C) 1999 Elsevier Science B.V.

  5. Novel humanized anti-CD20 antibody BM-ca binds to a unique epitope and exerts stronger cellular activity than others

    PubMed Central

    Kobayashi, Hideaki; Matsunaga, Yuka; Uchiyama, Yumiko; Nagura, Kenji; Komatsu, Yasuhiko

    2013-01-01

    Cellular activity of BM-ca, a novel humanized anti-CD20 antibody, was quantitatively compared with that of two other anti-CD20 antibodies used for clinical practice, rituximab and ofatumumab. The results of a complement-dependent cytotoxicity (CDC) assay revealed that the strongest antibody was ofatumumab, followed by BM-ca, with rituximab being the weakest. Ofatumumab and BM-ca were effective not only against rituximab-sensitive SU-DHL-4 cells but also against rituximab-resistant RC-K8 cells. In an antibody-dependent cell-mediated cytotoxicity (ADCC) assay, although the effective concentrations against SU-DHL-4 cells were almost the same among these three antibodies, the maximum cytotoxic level was the highest for BM-ca. In an anti-cell proliferation assay using SU-DHL-4 cells, BM-ca was the most effective and ofatumumab, the weakest. Against RC-K8 cells, only BM-ca was effective. When combined with each of four cancer chemotherapeutics (prednisolone, vincristine, hydroxydaunorubicin, and cisplatin), BM-ca exerted the most effective combinatorial anti-cell proliferation activity. To assess the in vivo effect of BM-ca, we intravenously administered BM-ca into cynomolgus monkeys and found that the peripheral B-cell levels did not decrease in half of the animals. Sequencing of cDNA encoding CD20 of cynomolgus monkeys revealed that the responders and nonresponders had Leu/Pro (hetero) and Leu/Leu (homo) at amino acid (a.a.) position 160, respectively, suggesting that the epitope recognized by BM-ca was around this a.a. By analyzing reactivity to synthetic peptides, the epitope recognized by BM-ca was estimated to be a.a.'s 156–166, not shared with rituximab and ofatumumab. These results suggest BM-ca to be a promising anti-CD20 antibody having superior properties and recognizing a unique epitope. PMID:23634281

  6. Novel humanized anti-CD20 antibody BM-ca binds to a unique epitope and exerts stronger cellular activity than others.

    PubMed

    Kobayashi, Hideaki; Matsunaga, Yuka; Uchiyama, Yumiko; Nagura, Kenji; Komatsu, Yasuhiko

    2013-04-01

    Cellular activity of BM-ca, a novel humanized anti-CD20 antibody, was quantitatively compared with that of two other anti-CD20 antibodies used for clinical practice, rituximab and ofatumumab. The results of a complement-dependent cytotoxicity (CDC) assay revealed that the strongest antibody was ofatumumab, followed by BM-ca, with rituximab being the weakest. Ofatumumab and BM-ca were effective not only against rituximab-sensitive SU-DHL-4 cells but also against rituximab-resistant RC-K8 cells. In an antibody-dependent cell-mediated cytotoxicity (ADCC) assay, although the effective concentrations against SU-DHL-4 cells were almost the same among these three antibodies, the maximum cytotoxic level was the highest for BM-ca. In an anti-cell proliferation assay using SU-DHL-4 cells, BM-ca was the most effective and ofatumumab, the weakest. Against RC-K8 cells, only BM-ca was effective. When combined with each of four cancer chemotherapeutics (prednisolone, vincristine, hydroxydaunorubicin, and cisplatin), BM-ca exerted the most effective combinatorial anti-cell proliferation activity. To assess the in vivo effect of BM-ca, we intravenously administered BM-ca into cynomolgus monkeys and found that the peripheral B-cell levels did not decrease in half of the animals. Sequencing of cDNA encoding CD20 of cynomolgus monkeys revealed that the responders and nonresponders had Leu/Pro (hetero) and Leu/Leu (homo) at amino acid (a.a.) position 160, respectively, suggesting that the epitope recognized by BM-ca was around this a.a. By analyzing reactivity to synthetic peptides, the epitope recognized by BM-ca was estimated to be a.a.'s 156-166, not shared with rituximab and ofatumumab. These results suggest BM-ca to be a promising anti-CD20 antibody having superior properties and recognizing a unique epitope. PMID:23634281

  7. Refinement of Eutectic Si in High Purity Al-5Si Alloys with Combined Ca and P Additions

    NASA Astrophysics Data System (ADS)

    Ludwig, Thomas Hartmut; Li, Jiehua; Schaffer, Paul Louis; Schumacher, Peter; Arnberg, Lars

    2015-01-01

    The effects of combined additions of Ca and P on the eutectic Si in a series of high purity Al-5 wt pct Si alloys have been investigated with the entrained droplet technique and complementary sets of conventional castings. Differential scanning calorimetry (DSC) and thermal analysis were used to investigate the eutectic droplet undercooling and the recalescence undercooling, respectively. Optical microscopy, SEM, EPMA, and TEM were employed to characterize the resultant microstructures. It was found that 250 ppm Ca addition to Al-5Si wt pct alloys with higher P contents leads to a significant increase of the eutectic droplet undercooling. For low or moderate cooling rates, the TEM results underline that Ca additions do not promote Si twinning. Thus, a higher twin density cannot be expected in Ca containing Al-Si alloys after, e.g., sand casting. Consequently, a refinement of the eutectic Si from coarse flake-like to fine plate-like structure, rather than a modification of the eutectic Si to a fibrous morphology, was achieved. This strongly indicates that the main purpose of Ca additions is to counteract the coarsening effect of the eutectic Si imposed by higher P concentrations. Significant multiple Si twinning was observed in melt-spun condition; however, this can be attributed to the higher cooling rate. After DSC heating (slow cooling), most of Si twins disappeared. Thus, the well-accepted impurity-induced twinning mechanism may be not valid in the case of Ca addition. The possible refinement mechanisms were discussed in terms of nucleation and growth of eutectic Si. We propose that the pre-eutectic Al2Si2Ca phase and preferential formation of Ca3P2 deactivate impurity particles, most likely AlP, poisoning the nucleation sites for eutectic Si.

  8. Interaction of an aluminum atom with an alkaline earth atom: Spectroscopic and ab initio investigations of AlCa

    NASA Astrophysics Data System (ADS)

    Behm, Jane M.; Morse, Michael D.; Boldyrev, Alexander I.; Simons, Jack

    1994-10-01

    A spectroscopic analysis of diatomic AlCa generated by laser vaporization of a 2:1 Al:Ca metal alloy followed by supersonic expansion has been completed using resonant two-photon ionization spectroscopy. Four excited electronic states have been identified and investigated in the energy region from 13 500 to 17 900 cm-1. These are the [13.5] 2Πr, the [15.8] 2Σ, the [17.0] 2Δ3/2(?), and the [17.6] 2Δ3/2 states. From rotational analysis excited state bond lengths have been measured for three of the four excited states, and the ground state has been unambiguously determined as a 2Πr state with a weighted least squares value of the ground state bond length of r0` = 3.1479± 0.0010 Å. The ionization energy of the molecule has also been directly determined as 5.072±0.028 eV. Ab initio calculations for the potential energy curves of seven low-lying states of AlCa [X 2Πr, 2Σ+, 4Σ-, 4Πr, 2Πr(2), 2Δ, and 2Σ-] and for the X 1Σ+ ground electronic state of AlCa+ have been carried out. In agreement with experiment, 2Πr is calculated to be the ground electronic state of the neutral molecule. The dissociation energies of AlCa (X 2Πr) into Al(3s23p1,2P0)+Ca(4s2,1S) and for AlCa+ (X 1Σ+) into Al+(3s2,1S)+Ca(4s2,1S) are calculated to be 0.47 and 1.50 eV, respectively. The excited 2Σ+, 4Σ-, 4Πr, 2Πr(2), 2Δ, and 2Σ- states are calculated to lie 0.2, 0.7, 0.7, 1.1, 1.1, and 1.1 eV above X 2Πr, respectively, and the vertical and adiabatic ionization energies of AlCa have been calculated to be 5.03 and 4.97 eV, respectively.

  9. Enthalpies of formation of CaAl sub 4 O sub 7 and CaAl sub 12 O sub 19 (hibonite) by high temperature, alkali borate solution calorimetry

    SciTech Connect

    Geiger, C.A.; Kleppa, O.J.; Mysen, B.O.; Lattimer, J.M.; Grossman, L. )

    1988-06-01

    The enthalpies of formation of CaAl{sub 4}O{sub 7} and CaAl{sub 12}O{sub 19} (hibonite), by alkali borate solution calorimetry at 1063 K are discussed. Using these experimental enthalpy data for CaAl{sub 4}O{sub 7} and estimated values for CaAl{sub 12}O{sub 19}, the standard enthalpies of formation of these compounds from the elements at 298 K are derived. Comparison with high-temperature galvanic cell data for the Gibbs energy of formation of CaAl{sub 12}O{sub 19} allows a calculation of the standard entropy of hibonite. This value is only about 2% larger than the oxide sum. Hence it is inferred that the standard entropy of hibonite at 298 K is probably only slightly larger than oxide sum value of 343.7 J/K g.f.w. The present data were used to extrapolate Kumar and Kay's (1985) data for the Gibbs energies of formation of hibonite and CaAl{sub 4}O{sub 7} to the temperature range 1500-1700 K. These data were then used in equilibrium thermodynamic calculations of the condensation of a gas of solar composition. Contrary to calculations of Kornacki and Fegley (1984), who used thermodynamic data of Allibert et al. (1981) for calcium aluminates, the authors results show no stability field for CaAl{sub 4}O{sub 7} in a gas of solar composition at 10{sup {minus}3} to 10{sup {minus}5} atm total pressure. At 10{sup {minus}3} atm pressure, hibonite forms by reaction of corundum with the gas at 1725 K, begins to react with the gas to form gehlenite at 1607 K and disappears completely in a reaction to form spinel at 1494 K. The absence of CaAl{sub 4}O{sub 7}, from hibonite-, spinel-rich inclusions in carbonaceous chondrites cannot be used as an argument against a condensation origin for these objects.

  10. Growth and spectral characters of Nd:CaGdAlO4 crystal

    NASA Astrophysics Data System (ADS)

    Di, Juqing; Sun, Xiaohui; Xu, Xiaodong; Xia, Changtai; Sai, Qinglin; Yu, Haohai; Wang, Yicheng; Zhu, Liu; Gao, Yuan; Guo, Xueyi

    2016-04-01

    In this paper, crystal growth and polarized spectra of Nd:CaGdAlO4 (Nd:CALGO) crystal were reported. The maximal absorption cross-sections are 6.8 and 7.5 × 10-20 cm2 for π-polarization and σ-polarization, and the emission cross-sections are 12.5 × 10-20 cm2 with full width at half maximum (FWHM) of 18 and 11 nm, respectively. The Judd-Ofelt (JO) theory was used to calculate the spectral parameters and the effective intensity parameters Ω2, Ω4 and Ω6 were 0.8 × 10-20 cm2, 7.5 × 10-20 cm2 and 5.8 × 10-20 cm2, respectively. The lifetime was 123 μs. The results show that Nd:CALGO crystal is a promising medium for laser output.

  11. Photoluminescence and thermoluminescence studies of CaAl2O4:Dy(3+) phosphor.

    PubMed

    Ziyauddin, Mohammad; Tigga, Shalinta; Brahme, Nameeta; Bisen, D P

    2016-02-01

    Calcium aluminate phosphors activated by Dy(3+) have been prepared by a combustion method at a temperature of 600°C. Photoluminescence (PL) and thermoluminescence (TL) properties of gamma-irradiated Dy-doped calcium aluminate were investigated. The PL spectrum shows a broad peak around 488 nm and 573 nm, under 347 nm excitation. Thermoluminescence studies were performed for different concentrations of Dy. Optimum intensity of photoluminescence was found for 0.02 mol% concentration of Dy. It was found that initially the peak TL intensity increases with increasing concentration of Dy in the CaAl2O4 host, attains a maximum value for 0.05 mol% concentration and decreases with further increase in the doping concentration due to concentration quenching.

  12. Passivation Effect of Atomic Layer Deposition of Al2O3 Film on HgCdTe Infrared Detectors

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Ye, Zhen-Hua; Sun, Chang-Hong; Chen, Yi-Yu; Zhang, Tian-Ning; Chen, Xin; Lin, Chun; Ding, Ring-Jun; He, Li

    2016-09-01

    The passivation effect of atomic layer deposition of (ALD) Al2O3 film on a HgCdTe infrared detector was investigated in this work. The passivation effect of Al2O3 film was evaluated by measuring the minority carrier lifetime, capacitance versus voltage ( C- V) characteristics of metal-insulator-semiconductor devices, and resistance versus voltage ( R- V) characteristics of variable-area photodiodes. The minority carrier lifetime, C- V characteristics, and R- V characteristics of HgCdTe devices passivated by ALD Al2O3 film was comparable to those of HgCdTe devices passivated by e-beam evaporation of ZnS/CdTe film. However, the baking stability of devices passivated by Al2O3 film is inferior to that of devices passivated by ZnS/CdTe film. In future work, by optimizing the ALD Al2O3 film growing process and annealing conditions, it may be feasible to achieve both excellent electrical properties and good baking stability.

  13. Ca2+ Binding/Permeation via Calcium Channel, CaV1.1, Regulates the Intracellular Distribution of the Fatty Acid Transport Protein, CD36, and Fatty Acid Metabolism.

    PubMed

    Georgiou, Dimitra K; Dagnino-Acosta, Adan; Lee, Chang Seok; Griffin, Deric M; Wang, Hui; Lagor, William R; Pautler, Robia G; Dirksen, Robert T; Hamilton, Susan L

    2015-09-25

    Ca(2+) permeation and/or binding to the skeletal muscle L-type Ca(2+) channel (CaV1.1) facilitates activation of Ca(2+)/calmodulin kinase type II (CaMKII) and Ca(2+) store refilling to reduce muscle fatigue and atrophy (Lee, C. S., Dagnino-Acosta, A., Yarotskyy, V., Hanna, A., Lyfenko, A., Knoblauch, M., Georgiou, D. K., Poché, R. A., Swank, M. W., Long, C., Ismailov, I. I., Lanner, J., Tran, T., Dong, K., Rodney, G. G., Dickinson, M. E., Beeton, C., Zhang, P., Dirksen, R. T., and Hamilton, S. L. (2015) Skelet. Muscle 5, 4). Mice with a mutation (E1014K) in the Cacna1s (α1 subunit of CaV1.1) gene that abolishes Ca(2+) binding within the CaV1.1 pore gain more body weight and fat on a chow diet than control mice, without changes in food intake or activity, suggesting that CaV1.1-mediated CaMKII activation impacts muscle energy expenditure. We delineate a pathway (Cav1.1→ CaMKII→ NOS) in normal skeletal muscle that regulates the intracellular distribution of the fatty acid transport protein, CD36, altering fatty acid metabolism. The consequences of blocking this pathway are decreased mitochondrial β-oxidation and decreased energy expenditure. This study delineates a previously uncharacterized CaV1.1-mediated pathway that regulates energy utilization in skeletal muscle.

  14. Ca2+ Binding/Permeation via Calcium Channel, CaV1.1, Regulates the Intracellular Distribution of the Fatty Acid Transport Protein, CD36, and Fatty Acid Metabolism*

    PubMed Central

    Georgiou, Dimitra K.; Dagnino-Acosta, Adan; Lee, Chang Seok; Griffin, Deric M.; Wang, Hui; Lagor, William R.; Pautler, Robia G.; Dirksen, Robert T.; Hamilton, Susan L.

    2015-01-01

    Ca2+ permeation and/or binding to the skeletal muscle L-type Ca2+ channel (CaV1.1) facilitates activation of Ca2+/calmodulin kinase type II (CaMKII) and Ca2+ store refilling to reduce muscle fatigue and atrophy (Lee, C. S., Dagnino-Acosta, A., Yarotskyy, V., Hanna, A., Lyfenko, A., Knoblauch, M., Georgiou, D. K., Poché, R. A., Swank, M. W., Long, C., Ismailov, I. I., Lanner, J., Tran, T., Dong, K., Rodney, G. G., Dickinson, M. E., Beeton, C., Zhang, P., Dirksen, R. T., and Hamilton, S. L. (2015) Skelet. Muscle 5, 4). Mice with a mutation (E1014K) in the Cacna1s (α1 subunit of CaV1.1) gene that abolishes Ca2+ binding within the CaV1.1 pore gain more body weight and fat on a chow diet than control mice, without changes in food intake or activity, suggesting that CaV1.1-mediated CaMKII activation impacts muscle energy expenditure. We delineate a pathway (Cav1.1→ CaMKII→ NOS) in normal skeletal muscle that regulates the intracellular distribution of the fatty acid transport protein, CD36, altering fatty acid metabolism. The consequences of blocking this pathway are decreased mitochondrial β-oxidation and decreased energy expenditure. This study delineates a previously uncharacterized CaV1.1-mediated pathway that regulates energy utilization in skeletal muscle. PMID:26245899

  15. Ultrasonically-enhanced mechanochemical synthesis of CaAl-layered double hydroxides intercalated by a variety of inorganic anions.

    PubMed

    Szabados, Márton; Mészáros, Rebeka; Erdei, Szabolcs; Kónya, Zoltán; Kukovecz, Ákos; Sipos, Pál; Pálinkó, István

    2016-07-01

    CaAl-layered double hydroxides (CaAl-LDHs) were synthesised with various interlayer anions (CO3(2-), F(-), Cl(-), Br(-) and I(-)) by mechanochemical pre-treatment followed by ultrasonic irradiation in aqueous media. The parameters of the syntheses (duration of pre-milling and sonication, quality of the aqueous media, temperature) were altered in order to optimise the procedure and to understand the formation of LDH and other secondary products. The products were characterised by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The optimisation resulted in close-to-phase-pure CaAl-LDHs, not only with carbonate and chloride interlayer anions, but the hard-to-intercalate bromide and iodide as well.

  16. Band bending at Al, In, Ag, and Pt interfaces with CdTe and ZnTe (110)

    SciTech Connect

    Wahi, A.K.; Miyano, K.; Carey, G.P.; Chiang, T.T.; Lindau, I.; Spicer, W.E. )

    1990-05-01

    Band bending behavior and interfacial chemistry for Al, In, Ag, and Pt overlayers on vacuum-cleaved {ital p}-CdTe and {ital p}-ZnTe (110) have been studied using ultraviolet photoelectron spectroscopy (UPS) and x-ray photoelectron spectroscopy (XPS). These metals provide a range of metal--substrate reactivities: Al reacts strongly with Te, Ag moderately, and In minimally, with no evidence seen for In reaction on ZnTe. Pt exhibits strong alloying behavior with both Cd and Zn. All four metals are found to yield Schottky barriers on CdTe and ZnTe, with a narrow range of final Fermi level positions, {ital E}{sub {ital fi}}={ital E}{sub {ital f}}{minus}{ital E}{sub VBM}, observed on CdTe, from 0.9 to 1.05{plus minus}0.1 eV, and on ZnTe from 0.65 to 1.0{plus minus}0.1 eV. The prediction of the MIGS model that a difference in barrier height exists for two semiconductors dependent upon their band lineup (valence band offset) is examined and found to agree with experiment for Ag, Pt, and Al, but not for In. For the highly reactive Al, no evidence for the overlayer metallicity required for metal-induced gap states (MIGS) to operate is seen on CdTe or ZnTe until after band bending has stabilized. Reaction and intermixing for Al, Ag, and Pt overlayers on CdTe and ZnTe indicate these interfaces are not ideal. The possible role of defects at these four metal/CdTe and metal/ZnTe interfaces is considered, and provides a consistent explanation for the final Fermi level positions observed.

  17. Microwave dielectric properties of CaCu3Ti4O12-Al2O3 composite

    NASA Astrophysics Data System (ADS)

    Rahman, Mohd Fariz Ab; Abu, Mohamad Johari; Karim, Saniah Ab; Zaman, Rosyaini Afindi; Ain, Mohd Fadzil; Ahmad, Zainal Arifin; Mohamed, Julie Juliewatty

    2016-07-01

    (1-x)CaCu3Ti4O12 + (x)Al2O3 composite (0 ≤ x ≤0.25) was prepared via conventional solid-state reaction method. The fabrication of sample was started with synthesizing stoichiometric CCTO from CaCO3, CuO and TiO2 powders, then wet-mixed in deionized water for 24 h. The process was continued with calcined CCTO powder at 900 °C for 12 h before sintered at 1040 °C for 10 h. Next, the calcined CCTO powder with different amount of Al2O3 were mixed for 24 h, then palletized and sintered at 1040 °C for 10. X-ray diffraction analysis on the sintered samples showed that CCTO powder was in a single phase, meanwhile the trace of secondary peaks which belong to CaAl2O4 and Corundum (Al2O3) could be observed in the other samples Scanning electron microscopy analysis showed that the grain size of the sample is firstly increased with addition of Al2O3 (x = 0.01), then become smaller with the x > 0.01. Microwave dielectric properties showed that the addition of Al2O3 (x = 0.01) was remarkably reduced the dielectric loss while slightly increased the dielectric permittivity. However, further addition of Al2O3 was reduced both dielectric loss and permittivity at least for an order of magnitude.

  18. Free-electron-like Hall effect and deviations from free-electron behavior in Ca-Al amorphous alloys

    NASA Astrophysics Data System (ADS)

    Mayeya, F. M.; Hickey, B. J.; Howson, M. A.

    1995-06-01

    The Hall coefficients of Ca-Al amorphous alloys have been measured at 4.2 K over a wide range of compositions. It is shown that the magnitude of the Hall coefficients are close to the nearly-free-electron (NFE) prediction for low Ca concentrations but deviate significantly from the NFE values for Ca concentration greater than 45 at. %. The deviations from the free-electron values have previously been attributed to the effects of s-d hybridization, while a reduction in magnitude by Au doping has been argued to result from the side-jump effect.

  19. Investigation of Al doping concentration effect on the structural and optical properties of the nanostructured CdO thin film

    NASA Astrophysics Data System (ADS)

    Gencer Imer, Arife

    2016-04-01

    Nanostructured aluminium (Al) doped cadmium oxide (CdO) films with highly electrical conductivity and optical transparency have been deposited for the first time on soda-lime glass substrates preheated at 250 °C by ultrasonic spray coating technique. The aluminium dopant content in the CdO film was changed from 0 to 5 at%. The influencing of Al doping on the structural, morphological, electrical and optical properties of the CdO nanostructured films has been investigated. Atomic force microscopy study showed the grain size of the films is an order of nanometers, and it decreases with increase in Al dopant content. All the films having cubic structure with a lattice parameter 4.69 Å were determined via X ray diffraction analysis. The optical band gap value of the films, obtained by optical absorption, was found to increase with Al doping. Electrical studies exhibited mobility, carrier concentration and resistivity of the film strongly dependent on the doping content. It has been evaluated that optical band gap, and grain size of the nanostructured CdO film could be modified by Al doping.

  20. Evaluating controlling factors to Al(i)/(Ca + Mg) molar ratio in acidic soil water, southern and southwestern China: multivariate approach.

    PubMed

    Guo, Jing-Heng; Zhang, Xiao-Shan; Vogt, Rolf D; Xiao, Jin-Song; Zhao, Da-Wei; Xiang, Ren-Jun; Luo, Jia-Hai

    2007-06-01

    Al(i)/(Ca + Mg) molar ratio in soil water has been used as an indicator to the effects of acid deposition on terrestrial ecosystems. However, the main factors controlling this ratio have not been well documented in southern and southwestern China. In this study, we presented the variation in inorganic aluminum (Al(i)) and Al(i)/(Ca + Mg) molar ratio in different sites and soil horizons based on two to three years monitoring data, and evaluated the main factors controlling Al(i)/(Ca + Mg) molar ratio using principle component analysis (PCA) and partial least square (PLS) regression. Monitoring data showed although Al(i)/(Ca + Mg) molar ratios in most soil water were lower than assumed critical 1.0, higher molar ratios were found in some soil water at TSP and LXH site. Besides acid loading, both soil properties and soil water chemistry affected the value of Al(i)/(Ca + Mg) molar ratio in soil water. Partial least square (PLS) indicated that they had different relative importance in different soil horizons. In A-horizon, soil aluminum saturation (AlS) had higher influence on Al(i)/(Ca + Mg) molar ratio than soil water chemistry did; higher soil aluminum saturation (AlS) led to higher Al(i)/(Ca + Mg) molar ratio in soil water. In the deeper horizons (i.e., B(1)-, B(2)- and BC-horizon), inorganic aluminum (Al(i)) in soil water had more and more important role in regulating Al(i)/(Ca + Mg) molar ratio. On regional scale, soil aluminum saturation (AlS) as well as cation exchange capacity (CEC) was the dominant factor controlling Al(i)/(Ca + Mg) molar ratio. This should be paid enough attention on when making regional acid rain control policy in China.

  1. Evaluating controlling factors to Al(i)/(Ca + Mg) molar ratio in acidic soil water, southern and southwestern China: multivariate approach.

    PubMed

    Guo, Jing-Heng; Zhang, Xiao-Shan; Vogt, Rolf D; Xiao, Jin-Song; Zhao, Da-Wei; Xiang, Ren-Jun; Luo, Jia-Hai

    2007-06-01

    Al(i)/(Ca + Mg) molar ratio in soil water has been used as an indicator to the effects of acid deposition on terrestrial ecosystems. However, the main factors controlling this ratio have not been well documented in southern and southwestern China. In this study, we presented the variation in inorganic aluminum (Al(i)) and Al(i)/(Ca + Mg) molar ratio in different sites and soil horizons based on two to three years monitoring data, and evaluated the main factors controlling Al(i)/(Ca + Mg) molar ratio using principle component analysis (PCA) and partial least square (PLS) regression. Monitoring data showed although Al(i)/(Ca + Mg) molar ratios in most soil water were lower than assumed critical 1.0, higher molar ratios were found in some soil water at TSP and LXH site. Besides acid loading, both soil properties and soil water chemistry affected the value of Al(i)/(Ca + Mg) molar ratio in soil water. Partial least square (PLS) indicated that they had different relative importance in different soil horizons. In A-horizon, soil aluminum saturation (AlS) had higher influence on Al(i)/(Ca + Mg) molar ratio than soil water chemistry did; higher soil aluminum saturation (AlS) led to higher Al(i)/(Ca + Mg) molar ratio in soil water. In the deeper horizons (i.e., B(1)-, B(2)- and BC-horizon), inorganic aluminum (Al(i)) in soil water had more and more important role in regulating Al(i)/(Ca + Mg) molar ratio. On regional scale, soil aluminum saturation (AlS) as well as cation exchange capacity (CEC) was the dominant factor controlling Al(i)/(Ca + Mg) molar ratio. This should be paid enough attention on when making regional acid rain control policy in China. PMID:17057971

  2. Microstructural and Mössbauer properties of low temperature synthesized Ni-Cd-Al ferrite nanoparticles

    PubMed Central

    2011-01-01

    We report the influence of Al3+ doping on the microstructural and Mössbauer properties of ferrite nanoparticles of basic composition Ni0.2Cd0.3Fe2.5 - xAlxO4 (0.0 ≤ x ≤ 0.5) prepared through simple sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray, transmission electron microscopy (TEM), Fourier transformation infrared (FTIR), and Mössbauer spectroscopy techniques were used to investigate the structural, chemical, and Mössbauer properties of the grown nanoparticles. XRD results confirm that all the samples are single-phase cubic spinel in structure excluding the presence of any secondary phase corresponding to any structure. SEM micrographs show the synthesized nanoparticles are agglomerated but spherical in shape. The average crystallite size of the grown nanoparticles was calculated through Scherrer formula and confirmed by TEM and was found between 2 and 8 nm (± 1). FTIR results show the presence of two vibrational bands corresponding to tetrahedral and octahedral sites. Mössbauer spectroscopy shows that all the samples exhibit superparamagnetism, and the quadrupole interaction increases with the substitution of Al3+ ions. PMID:21851597

  3. Effect of salinity on the skeletal chemistry of cultured scleractinian zooxanthellate corals: Cd/Ca ratio as a potential proxy for salinity reconstruction

    NASA Astrophysics Data System (ADS)

    Pretet, Chloé; Reynaud, Stéphanie; Ferrier-Pagès, Christine; Gattuso, Jean-Pierre; Kamber, Balz S.; Samankassou, Elias

    2014-03-01

    The effect of salinity on the elemental and isotopic skeletal composition of modern zooxanthellate scleractinian corals ( Acropora sp., Montipora verrucosa and Stylophora pistillata) was investigated in order to evaluate potential salinity proxies. Corals were cultured in the laboratory at three salinities (36, 38 and 40). The other environmental parameters were kept constant. For all species analyzed, Sr/Ca, Mg/Ca, U/Ca and Li/Ca ratios were not influenced by salinity changes. The Ba/Ca ratio also lacks a systematic relationship with salinity and exhibits high inter-generic variations, up to one order of magnitude. On the contrary, the Cd/Ca ratio decreases as a function of increasing salinity, and δ18O and δ13C also presented a significant response, but with opposite trends to salinity variations. Since Cd/Ca is usually considered as an upwelling proxy, its salinity dependence could compromise the upwelling signal, unless some corrections can be carried out. Regardless, if the dependence found in the present dataset proved to be widespread and systematic, the Cd/Ca ratio could represent a promising salinometer awaiting further investigation. This study also confirmed the reliability of the well-established temperature proxies Sr/Ca, Mg/Ca and U/Ca, as these ratios were insensitive to salinity variations. Moreover, our results showed that δ18O or δ13C can be considered as reliable temperature recorders as far as the salinity effect is removed from the parameter reconstructed (e.g., temperature). Investigating the influence of salinity on the skeletal chemistry of scleractinian corals grown under controlled environmental conditions confirmed previous results, validated isotopic corrections, and identified a promising proxy of salinity.

  4. Progress in the material development of LiCaAlF sub 6 :Cr sup 3+ laser crystals

    SciTech Connect

    Michelle D. Shinn.; Chase, L.L.; Caird, J.A.; Payne, S.A.; Atherton, L.J.; Kway, W.L.

    1990-03-01

    High Cr{sup 3+} doping levels, up to 8 mole percent, and low losses have been obtained with the tunable solid-state laser material LiCaAlF{sub 6}:Cr{sup 3+} (Cr:LiCAF). Measurements and calculations show that high pumping and extraction efficiencies are possible with the improved material. 13 refs., 4 figs., 1 tab.

  5. Photoelectron velocity-map imaging and theoretical studies of heteronuclear metal carbonyls MNi(CO)3- (M = Mg, Ca, Al)

    NASA Astrophysics Data System (ADS)

    Xie, Hua; Zou, Jinghan; Yuan, Qinqin; Fan, Hongjun; Tang, Zichao; Jiang, Ling

    2016-03-01

    The heteronuclear metal carbonyl anions MNi(CO)3- (M = Mg, Ca, Al) have been investigated using photoelectron velocity-map imaging spectroscopy. Electron affinities of neutral MNi(CO)3 (M = Mg, Ca, Al) are measured from the photoelectron spectra to be 1.064 ± 0.063, 1.050 ± 0.064, and 1.541 ± 0.040 eV, respectively. The C-O stretching mode in these three clusters is observed and the vibrational frequency is determined to be 2049, 2000, and 2041 cm-1 for MgNi(CO)3, CaNi(CO)3, and AlNi(CO)3, respectively. Density functional theory calculations are carried out to elucidate the geometric and electronic structures and to aid the experimental assignments. It has been found that three terminal carbonyls are preferentially bonded to the nickel atom in these heterobinuclear nickel carbonyls MNi(CO)3-1/0, resulting in the formation of the Ni(CO)3 motif. Ni remains the 18-electron configuration for MgNi(CO)3 and CaNi(CO)3 neutrals, but not for AlNi(CO)3. This is different from the homobinuclear nickel carbonyl Ni-Ni(CO)3 with the involvement of three bridging ligands. Present findings would be helpful for understanding CO adsorption on alloy surfaces.

  6. Positron annihilation studies of the Al-Ca-Zn superplastic alloy: thermal and thermomechanical contribution

    SciTech Connect

    Ayciriex, M.D. ); Romero, R.; Somoza, A. ); Silvetti, S.P.; Villagra, O. )

    1993-06-15

    Positron annihilation spectroscopy (PAS) is an established method for the study of electronic structure and defect properties in metals and alloys. The application of this technique to the study of positron trapping in grain boundaries and related phenomena, however, is relatively scarce. The physical basis for the application of PAS to the study of grain boundaries is the fact that grain boundaries are regions of low atomic density which result in attractive sites to the trap positions. The superplastic alloys are particularly suitable materials to be studied with PAS; they have a fine-grained structure, and therefore a high density of grain boundaries. Moreover, in the annealed condition, they have a low density of other types of defects capable of trapping positrons, such as dislocations. This type of polycrystalline material can undergo extremely high deformations (up to hundreds and thousands percent) in a certain temperature-strain rate range without macroscopic failure. This paper is part of a whole study of the thermal and thermomechanical effects on the positron lifetime parameters and their relation with microstructural changes and the phenomenon of structural superplasticity in a Al-Ca-Zn alloy.

  7. Experimentally Produced Spinel Rims on Ca-Al-Rich Inclusion Bulk Compositions

    NASA Technical Reports Server (NTRS)

    Paque, Julie M.; Le, L.; Lofgren, G. E.

    1998-01-01

    Most Ca-Al-rich inclusions (CAls) from Allende are surrounded by a series of mineralogically distinct rim layers. Proposed modes of formation for these layers include flash heating, evaporation, and condensation. The innermost of these rim layers is generally spinel (SP), in some cases intergrown with perovskite (PV), and commonly containing varying amounts of secondary iron increasing towards the edge of the CAI. The SP or SP+PV rim is not always contiguous with the other rim layers, indicating that it is probably the result of a separate event. We have produced continuous SP rims on synthetic analogs representing Type A/B1, average Type B, and Type B2 bulk compositions by reheating a solid glass experimental charge to subliquidus crystallization temperatures. This experimental result is consistent with the formation of chondrules; and CAIs by more than one sequence of heating and cooling. Previous work indicated that prior crystallization events produced observable effects in the texture and chemistry of the final run product. Information on the nature of the heating/cooling cycles experienced by CAls and chondrules is important in modeling the environment of their formation. Additional information is contained in the original extended abstract.

  8. Discharge properties of Mg-Al-Mn-Ca and Mg-Al-Mn alloys as anode materials for primary magnesium-air batteries

    NASA Astrophysics Data System (ADS)

    Yuasa, Motohiro; Huang, Xinsheng; Suzuki, Kazutaka; Mabuchi, Mamoru; Chino, Yasumasa

    2015-11-01

    The discharge behaviors of rolled Mg-6 mass%Al-0.3 mass%Mn-2 mass%Ca (AMX602) and Mg-6 mass%Al-0.3 mass%Mn (AM60) alloys used as anodes for Magnesium-air batteries were investigated. The AMX602 alloy exhibited superior discharge properties compared to the AM60 alloy, especially at low current density. The discharge products of the AMX602 alloy were dense and thin, and many cracks were observed at all current densities. In addition, the discharge products were detached at some sites. These sites often corresponded to the positions of Al2Ca particles. The comparison of the discharge and corrosion tests indicated that the dense and thin discharge products of AMX602 were easily cracked by dissolution of the Mg matrix around Al2Ca particles, and the cracks promoted the penetration of the electrolyte into the discharge products, retaining the discharge activity. In contrast, concerning the AM60 alloy, thick discharge products were formed on the surface during discharge, and cracking of the discharge products hardly occurred, degrading the discharge properties. Localized and deeply corroded pits that could result from the detachment of metal pieces from the anode during discharge were partly observed in the AM60 alloy. It is suggested that these detached metal pieces are another reason for the low discharge properties of the AM60 alloy.

  9. Microstructure and Fatigue Behavior of Friction Stir-welded Noncombustive Mg-9Al-Zn-Ca Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Zhou, L.; Li, Z. Y.; Nakata, K.; Feng, J. C.; Huang, Y. X.; Liao, J. S.

    2016-06-01

    Microstructure and fatigue behavior of friction stir-welded noncombustive Mg-9Al-Zn-Ca magnesium alloy were investigated. The as-received hot-extruded material consisted of equiaxed α-Mg grains with β-Mg17Al12 and Al2Ca compounds distributed along the grain boundaries. Friction stir welding produced much refined α-Mg grains accompanied by the dissolution of the eutectic β-Mg17Al12 phase, while Al2Ca phase was dispersed homogenously into the Mg matrix. Friction stir welding produced slightly increased hardness and tensile strength in the defect-free welds compared with the base material due to microstructural refinement and uniform distribution of intermetallic compounds. The load-controlled uniaxial tensile high-cycle fatigue tests indicated that fatigue strength of 90 MPa was obtained for the friction stir-welded joint with fatigue crack initiated basically near the specimen's surface and at the retreating side of the joint. Crack propagation was characterized by cleavage and fatigue striations.

  10. Rapid burst of H2O2 by plant growth regulators increases intracellular Ca2+ amounts and modulates CD4+ T cell activation.

    PubMed

    Ahmed, Asma; Mukherjee, Sambuddho; Deobagkar, Mukta; Naik, Tanushree; Nandi, Dipankar

    2010-11-01

    The identification of small molecules that affect T cell activation is an important area of research. Three molecules that regulate plant growth and differentiation, but not their structurally similar analogs, were identified to enhance primary mouse CD4(+) T cell activation in conjunction with soluble anti-CD3 stimulation: Indoleacetic acid (natural plant auxin), 1-Napthaleneacetic acid (synthetic plant auxin) and 2,4-Dichlorophenoxyacetic acid (synthetic plant auxin and herbicide). These effects are distinct in comparison to Curcumin, the well known phenolic immunomodulator, which lowers T cell activation. An investigation into the mechanisms of action of the three plant growth regulators revealed a rapid induction of reactive oxygen species (ROS), mainly comprising H(2)O(2). In addition, these three molecules synergize with soluble anti-CD3 signaling to enhance intracellular Ca(2+) concentrations [Ca(2+)](i), leading to greater T cell activation, e.g. induction of CD25 and IL-2. Enhanced production of TNFα and IFNγ by CD4(+) T cells is also observed upon plant growth regulator treatment with soluble anti-CD3. Interestingly, maximal IL-2 production and CD4(+) T cell cycle progression are observed upon activation with soluble anti-CD3 and phorbol 12-myristate 13-acetate (PMA), a phorbol ester. Additionally, stimulation with PMA and Ionomcyin (a Ca(2+) ionophore), which activates T cells by circumventing the TCR, and plant growth regulators also demonstrated the role of the strength of signal (SOS): T cell cycle progression is enhanced with gentle activation conditions but decreased with strong activation conditions. This study demonstrates the direct effects of three plant growth regulators on CD4(+) T cell activation and cycling.

  11. Constraints on Titanite Acitvity in the System CaTiSiO4O-CaAlSiO4F: Implications for Thermobarometry in Metamorphic Rocks

    NASA Astrophysics Data System (ADS)

    Tropper, P.; Manning, C. E.; Essene, E. J.

    2006-12-01

    Titanite is a common accessory mineral that could be used reliably in phase equilibrium calculations, if activity-composition relations in Al-F titanites were known. Troitzsch and Ellis (2001, CMP, 142, 543) and Tropper et al. (2002, JPet., 43, 1787) gave non-ideal mixing models along the join CaTiSiO4O- CaAlSiO4F. Tropper et al. (2002) derived a negative interaction parameter W, whereas Troitzsch and Ellis (2001) derived a regular model with both positive and negative W, but favored positive values. These differences strongly influence calculated CaTiSiO4O activity (attn). Although more experiments are needed, our result that γttn<1 at high T indicates a large degree of non-ideal behavior, even at >900°C, which in turn will affect thermobarometry. Comparing available activity models shows that at these T, attn is substantially underestimated by the fully ionic model used by Manning and Bohlen (1991, CMP, 109, 1), in which attn = XCaXTiXSi(XO)5. This model assumes independent mixing of Al for Ti and random mixing of F and O on all O sites. However, F substitutes only in one O site (O1; Oberti et al., 1991, EJM, 3, 777). A fully ionic model should therefore be recast as attn = XCaXTiXSiXO, where XO indicates the mole fraction of O on the (O1) site. The substitution of F on the O1 site is coupled with Al, so it is called the ideal coupled model. Unlike the regular model, the prefered ionic model departs strongly from ideality at ≤600°C, consistent with independent constraints. However, experimentally determined attn is approximated by an ideal molecular model (XTi) at ≥900°C, so this model is recommended for thermobarometry in high- T metamorphic rocks until more data are available. Recalculation of the P recorded by the three eclogites from Manning and Bohlen (1991) using the different activity models discussed here yields differences that may be as high as 2.0 GPa.

  12. Antiferromagnetism in CaAl2Si2-type CaMn2As2 and SrMn2As2 single crystals

    NASA Astrophysics Data System (ADS)

    Sangeetha, N. S.; Pandey, Abhishek; Benson, Zackery A.; Johnston, D. C.

    Magnetic susceptibility versus temperature χ (T) measurements of CaMn2As2 and SrMn2As2 crystals show clear antiferromagnetic (AFM) transitions at TN ~ 65 K and 120 K,1 respectively. The anisotropic behaviors in χ (T <=TN) suggest that both compounds are noncollinear antiferromagnets which may result either from an intrinsic noncollinear structure or from multiple collinear AFM domains that are not aligned collinearly.2 The χ (T) data at T >TN reveal that both compounds exhibit strong short-range AFM ordering, evidently associated with quasi-two-dimensional spin lattices. The electrical resistivities show insulating ground states with activation energies of ~ 63 meV in CaMn2As2 and 44 meV in SrMn2As2 . The experimental results thus reveal that both (Ca , Sr) Mn2As2 materials are AFM insulators at low temperatures and in analogy with the high Tc cuprates, may be potential parent compounds for CaAl2Si2-type superconductors. Work was supported by the USDOE under Contract No. DE-AC02-07CH11358.

  13. Phase equilibria and elements partitioning in zirconolite-rich region of Ca-Zr-Ti-Al-Gd-Si-O system

    SciTech Connect

    Knyazev, O.A.; Stefanovsky, S.V.; Ioudintsev, S.V.; Nikonov, B.S.; Omelianenko, B.I.; Mokhov, A.V.; Yakushev, A.I.

    1997-12-31

    Zirconolite-rich ceramics were produced by the cold crucible melting technique in an air atmosphere, at 1550 {+-} 50 C and 1 atm. Four samples with overall composition (in wt.%): 4.9-14.3 CaO; 19.0-41.3 ZrO{sub 2}; 24.1-42.6 TiO{sub 2}; 1.3-11.3 Al{sub 2}O{sub 3}; 6.8-30.0 Gd{sub 2}O{sub 3}; and 1.1-8.5 SiO{sub 2} have been studied. Total phases in the ceramics consist of major zirconolite and minor rutile, perovskite, zirconia, aluminium titanate, and glass. The Gd{sub 2}O{sub 3} content in zirconolite reaches up to 31.4 wt.% corresponding to the formula: (Ca{sub 0.4},Gd{sub 0.7})Zr{sub 1.0}(Ti{sub 1.4},Al{sub 0.5})O{sub 7.0}. The data on the phase composition agree well with coupled Gd incorporation into the mineral structure: Ca(II) + Ti(IV) = Gd(III) + Al(III), and 2Gd(III) = Ca(II) + Zr(IV). The highest Gd contents observed in the other phases are 25.4% for zirconia, 12.6% in glass, 8.8% in perovskite, and 1.4% for rutile. The rest of the elements` distribution in the samples are analyzed.

  14. Charge-compensation effect of Al on luminescence properties of M2(Si, Al)5N8:Ce3+ (M = Ca, Sr, Ba)

    NASA Astrophysics Data System (ADS)

    Kuramoto, Daiki; Horikawa, Takashi; Hanzawa, Hiromasa; Machida, Ken-ichi

    2013-09-01

    The charge-compensated materials, M2AlxSi5-xN8:Ce3+ (M = Ca, Sr, Ba), were synthesized from appropriate mixtures of MSi, MAlSi, (MSiHy, MAlSiHy), Si3N4 and CeF3 by a direct nitriding process in a N2 gas and the luminescence properties were characterized. The resultant phosphors showed green emission suitable for LED illumination by optimizing the mixing ratio of metal elements. These phosphors were effectively excited by violet or blue light (400-430 nm) and the emission bands were observed at various wavelength regions for Ca: 489-528 nm, Sr: 511-520 nm, and Ba: 508-514 nm. Although the emission intensity of Ca2(Si, Al)5N8:Ce3+ was decreased with increasing amount of Al, those of Sr- and Ba-analogues were maximized at x = 0.5 of Al content in M2Si5-xAlxN8:Ce3+.

  15. LiCaAlF6 scintillators in neutron and gamma radiation fields

    NASA Astrophysics Data System (ADS)

    Viererbl, L.; Klupák, V.; Vinš, M.; Koleška, M.; Šoltés, J.; Yoshikawa, A.; Nikl, M.

    2016-09-01

    Intentionally doped LiCaAlF6 (LiCAF) single crystals are prospective scintillators, especially for thermal neutron detection through the 6Li(n,t)4He nuclear reaction. Four different LiCAF scintillator samples were tested in various neutron and gamma fields. Two of the tested samples were LiCAF:Eu and LiCAF:Eu,Na single crystals, and another two samples were made of LiCAF:Eu micro crystals dispersed in transparent rubber, with different rubber dimensions. All LiCAF samples contain lithium enriched to6Li. A plutonium-beryllium source was used as a neutron source. The neutron spectrum was modified by moderator and filter to get different ratios between thermal, epithermal and fast neutron fluence rates. The MCNP code was used for calculations of the fluence rates for different configurations. Radionuclides 137Cs and 60Co were applied as gamma radiation sources. The light signal from the scintillator was evaluated with a photomultiplier and a multichannel analyzer. The purpose of this work was to study the characteristics of LiCAF scintillators, especially the ability to discriminate signals from neutron and gamma radiation, which is the basic scintillator condition for neutron detection in mixed neutron-gamma radiation fields. Generally, the discrimination can be done by the pulse height and/or the pulse shape of the evaluated signals. Both methods can be used for a LiCAF scintillator. However, only the pulse height discrimination method is discussed in this paper. The possibility of fast neutron detection with LiCAF scintillators was also tested.

  16. Crustal structure of and boundary between the AlCaPa and Tisza terrains in the Pannonian basin

    NASA Astrophysics Data System (ADS)

    Hetényi, György; Ren, Yong; Dando, Ben; Stuart, Graham W.; Houseman, Gregory A.

    2014-05-01

    The evolution of the Pannonian Basin is strongly linked to that of the surrounding Alpine, Carpathian and Dinaric orogens. The eastward extrusion of Alpine-type basement that accompanied lithospheric thinning must have been accompanied by mantle downwelling and/or subduction along the Carpathians but the motive forces for these movements are debated. The internal structure of the crust within the basin is mostly covered by relatively recent sedimentary infill whose variable thickness further complicates seismic imaging. Palaeomagnetic and geological data have, however, shown that two tectonic terrains of distinct origin: AlCaPa and Tisza, occupy the basin's NW and SE part respectively. The two units have undergone different amounts of extension during opposite orientation rotations (counter-clockwise and clockwise, respectively). The boundary between these two units, known as the Mid-Hungarian Zone, is recognized as a major sinistral shear zone, geophysically clearly marked across the basin by a trough in Bouguer gravity. The Carpathian Basins Project deployed 49 broadband seismological stations perpendicular to the boundary between the AlCaPa and Tisza units. A NW-SE oriented swath of three lines covers a 450 km long and 75 km wide area. We use these and 4 permanent stations to image the crustal structure of and the boundary between AlCaPa and Tisza using the receiver function technique. The measured Moho depths show no significant change in crustal thickness between the two terrains, but the Moho is not or very weakly imaged along a ca. 40 km wide strip centred on the MHZ. Our Moho depths elsewhere in the basin agree with earlier controlled-source seismic results and recent shear-wave velocity models deduced from ambient noise analysis. The lack of a sharp Moho image beneath the MHZ implies that the crust-mantle boundary between AlCaPa and Tisza is not a sharp transition but rather a gradual increase in velocity with depth. The distinct low in gravity anomalies

  17. Teaching the Modes of Ca[superscript 2+] Transport between the Plasma Membrane and Endoplasmic Reticulum Using a Classic Paper by Kwan et al.

    ERIC Educational Resources Information Center

    Liang, Willmann

    2009-01-01

    This teaching article uses the report by Kwan et al., "Effects of methacholine, thapsigargin, and La[superscript 3+] on plasmalemmal and intracellular Ca[superscript 2+] transport in lacrimal acinar cells," where the effects of Ca[superscript 2+]-mobilizing agents in regulating Ca[superscript 2+] fluxes were examined under various conditions.…

  18. The apoptotic members CD95, BclxL, and Bcl-2 cooperate to promote cell migration by inducing Ca(2+) flux from the endoplasmic reticulum to mitochondria.

    PubMed

    Fouqué, A; Lepvrier, E; Debure, L; Gouriou, Y; Malleter, M; Delcroix, V; Ovize, M; Ducret, T; Li, C; Hammadi, M; Vacher, P; Legembre, P

    2016-10-01

    Metalloprotease-processed CD95L (cl-CD95L) is a soluble cytokine that implements a PI3K/Ca(2+) signaling pathway in triple-negative breast cancer (TNBC) cells. Accordingly, high levels of cl-CD95L in TNBC women correlate with poor prognosis, and administration of this ligand in an orthotopic xenograft mouse model accelerates the metastatic dissemination of TNBC cells. The molecular mechanism underlying CD95-mediated cell migration remains unknown. Here, we present genetic and pharmacologic evidence that the anti-apoptotic molecules BclxL and Bcl-2 and the pro-apoptotic factors BAD and BID cooperate to promote migration of TNBC cells stimulated with cl-CD95L. BclxL was distributed in both endoplasmic reticulum (ER) and mitochondrion membranes. The mitochondrion-localized isoform promoted cell migration by interacting with voltage-dependent anion channel 1 to orchestrate Ca(2+) transfer from the ER to mitochondria in a BH3-dependent manner. Mitochondrial Ca(2+) uniporter contributed to this flux, which favored ATP production and cell migration. In conclusion, this study reveals a novel molecular mechanism controlled by BclxL to promote cancer cell migration and supports the use of BH3 mimetics as therapeutic options not only to kill tumor cells but also to prevent metastatic dissemination in TNBCs.

  19. The apoptotic members CD95, BclxL, and Bcl-2 cooperate to promote cell migration by inducing Ca2+ flux from the endoplasmic reticulum to mitochondria

    PubMed Central

    Fouqué, A; Lepvrier, E; Debure, L; Gouriou, Y; Malleter, M; Delcroix, V; Ovize, M; Ducret, T; Li, C; Hammadi, M; Vacher, P; Legembre, P

    2016-01-01

    Metalloprotease-processed CD95L (cl-CD95L) is a soluble cytokine that implements a PI3K/Ca2+ signaling pathway in triple-negative breast cancer (TNBC) cells. Accordingly, high levels of cl-CD95L in TNBC women correlate with poor prognosis, and administration of this ligand in an orthotopic xenograft mouse model accelerates the metastatic dissemination of TNBC cells. The molecular mechanism underlying CD95-mediated cell migration remains unknown. Here, we present genetic and pharmacologic evidence that the anti-apoptotic molecules BclxL and Bcl-2 and the pro-apoptotic factors BAD and BID cooperate to promote migration of TNBC cells stimulated with cl-CD95L. BclxL was distributed in both endoplasmic reticulum (ER) and mitochondrion membranes. The mitochondrion-localized isoform promoted cell migration by interacting with voltage-dependent anion channel 1 to orchestrate Ca2+ transfer from the ER to mitochondria in a BH3-dependent manner. Mitochondrial Ca2+ uniporter contributed to this flux, which favored ATP production and cell migration. In conclusion, this study reveals a novel molecular mechanism controlled by BclxL to promote cancer cell migration and supports the use of BH3 mimetics as therapeutic options not only to kill tumor cells but also to prevent metastatic dissemination in TNBCs. PMID:27367565

  20. Study of new sheep bone and Zn/Ca ratio around TiAlV screw: PIXE RBS analysis

    NASA Astrophysics Data System (ADS)

    Guibert, G.; Munnik, F.; Langhoff, J. D.; Von Rechenberg, B.; Buffat, Ph. A.; Laub, D.; Faber, L.; Ducret, F.; Gerber, I.; Mikhailov, S.

    2008-03-01

    This study reports on in vivo particle induced X-ray emission (PIXE) measurements combined with Rutherford backscattering spectroscopy (RBS) analyses of new remodeled sheep bone formed around TiAlV screws. The implants (screws) were anodized by a modified TiMax™ process. The interface between the implant and the bone was carefully investigated. [Zn]/[Ca] in-depth composition profiles as well as Ca, Fe elemental maps were recorded. The thickness of new bone formed around the screw reached 300-400 μm. Osteon and Osteoid phases were identified in the new bone. A higher [Zn]/[Ca] ratio was observed in the new bone as compared to the mature bone. Blood vessels were observed in the bone in close contact with the screw. This study shows the potential of ion beam analysis for biological and biomedical characterization.

  1. Structural investigations of {beta}-CaAlF{sub 5} by coupling powder XRD, NMR, EPR and spectroscopic parameter calculations

    SciTech Connect

    Body, M. . E-mail: monique.body@univ-lemans.fr; Silly, G.; Legein, C.; Buzare, J.-Y.; Calvayrac, F.; Blaha, P.

    2005-12-15

    {beta}-CaAlF{sub 5} was synthesized by solid-state reaction. The precise structure was refined from X-ray powder diffraction data in the monoclinic space group P2{sub 1}/c with lattice constants a=5.3361A, b=9.8298A, c=7.3271A, and {beta}=109.91{sup o} (Z=4). The structure exhibits isolated chains of AlF{sub 6}{sup 3-} octahedra sharing opposite corners.{sup 19}F and {sup 27}Al solid state NMR spectra were recorded using MAS and SATRAS techniques. An EPR spectrum was recorded for {beta}-CaAlF{sub 5}:Cr{sup 3+}. The experimental spectra were simulated in order to extract the NMR and EPR parameter values. Five fluorine sites and one low symmetry aluminium site were found in agreement with the refined structure. These parameters were calculated using empirical and ab-initio methods. The agreement obtained between the calculated {sup 19}F chemical shift values, {sup 27}Al quadrupolar parameters, Cr{sup 3+} EPR fine structure parameters and the experimental results demonstrates the complementarity of XRD, magnetic resonance experiments and theoretical methodologies.

  2. Synthesis and hydration behavior of calcium zirconium aluminate (Ca{sub 7}ZrAl{sub 6}O{sub 18}) cement

    SciTech Connect

    Kang, Eun-Hee; Yoo, Jun-Sang; Kim, Bo-Hye; Choi, Sung-Woo; Hong, Seong-Hyeon

    2014-02-15

    Calcium zirconium aluminate (Ca{sub 7}ZrAl{sub 6}O{sub 18}) cements were prepared by solid state reaction and polymeric precursor methods, and their phase evolution, morphology, and hydration behavior were investigated. In polymeric precursor method, a nearly single phase Ca{sub 7}ZrAl{sub 6}O{sub 18} was obtained at relatively lower temperature (1200 °C) whereas in solid state reaction, a small amount of CaZrO{sub 3} coexisted with Ca{sub 7}ZrAl{sub 6}O{sub 18} even at higher temperature (1400 °C). Unexpectedly, Ca{sub 7}ZrAl{sub 6}O{sub 18} synthesized by polymeric precursor process was the large-sized and rough-shaped powder. The planetary ball milling was employed to control the particle size and shape. The hydration behavior of Ca{sub 7}ZrAl{sub 6}O{sub 18} was similar to that of Ca{sub 3}Al{sub 2}O{sub 6} (C3A), but the hydration products were Ca{sub 3}Al{sub 2}O{sub 6}·6H{sub 2}O (C3AH6) and several intermediate products. Thus, Zr (or ZrO{sub 2}) stabilized the intermediate hydration products of C3A.

  3. The Effects of Cd2+ Concentration on the Structure, Optical and Luminescence Properties of MgAl2O4: x% Cd2+ (0 < x ≤ 1.75) Nanophosphor Prepared by Sol-Gel Method

    NASA Astrophysics Data System (ADS)

    Motloung, S. V.; Dejene, F. B.; Sithole, M. E.; Koao, L. F.; Ntwaeaborwa, O. M.; Swart, H. C.; Motaung, T. E.

    2016-10-01

    Cadmium-doped magnesium aluminate (MgAl2O4: x% Cd2+) powders with different cadmium concentrations (0 < x ≤ 1.75) were prepared by the sol-gel method. Energy dispersive x-ray spectroscopy (EDS) analysis confirmed the presence of the expected elements (Mg, Al, O, and Cd). The x-ray diffraction (XRD) analysis revealed that the powders crystallized into the cubic spinel structure. Cd2+ doping influenced crystallinity of the powder samples. The crystallite size and particle morphology were not affected by variation in the Cd2+ concentration. Ultraviolet-visible spectroscopy (UV-vis) measurements revealed that the band gap of the MgAl2O4 was influenced by Cd2+ doping. Un-doped and Cd2+-doped MgAl2O4 nanophosphors exhibited violet emission at 392 nm. There was no evidence of the emission peak shift, which suggested that all emissions originated from the defects within the host material. Increasing the Cd2+ concentration up-to 0.88 mol.% lead to luminescence intensity enhancement, while further increase of Cd2+ concentration lead to concentration quenching. The critical energy transfer distance ( R c) between the neighbouring donors and acceptors was found to be 5.21 Å, suggesting that the multipole-multipole interaction (M-MI) is the major cause of concentration quenching. Commission Internationale de l'Elcairage (CIE) colour coordinates confirmed non-tuneable violet emission with intensity dependent on the Cd2+ concentration.

  4. The Relative Nature of Perception: A Response to Cañal-Bruland and van der Kamp (2015)

    PubMed Central

    2015-01-01

    Cañal-Bruland and van der Kamp present an argument about the incommensurate relationship between affordance perception and spatial perception in a criticism of Proffitt and Linkenauger’s phenotypic approach to perception. Many of their criticisms are based on a difference in the interpretation of the core ideas underlying the phenotypic approach. The most important of these differences in interpretations concern fundamental assumptions about the nature of the perceptions of size and distance themselves. Extent perception must be relative to the organism; therefore, there can be no veridical perception of space. Also, we argue in the phenotypic approach that space perception is an emergent property of affordance perception; they are not different types of perceptions as Cañal-Bruland and van der Kamp presume. Third, affordance perception need not be perfectly accurate, just good enough. Additionally, affordance perception need not be dichotomous; this presumption likely originates in the methodology typically employed to study affordance perception. Finally, I agree with Cañal-Bruland and van der Kamp that joint research efforts will clarify and improve our understanding of these issues. PMID:27648215

  5. The Relative Nature of Perception: A Response to Cañal-Bruland and van der Kamp (2015)

    PubMed Central

    2015-01-01

    Cañal-Bruland and van der Kamp present an argument about the incommensurate relationship between affordance perception and spatial perception in a criticism of Proffitt and Linkenauger’s phenotypic approach to perception. Many of their criticisms are based on a difference in the interpretation of the core ideas underlying the phenotypic approach. The most important of these differences in interpretations concern fundamental assumptions about the nature of the perceptions of size and distance themselves. Extent perception must be relative to the organism; therefore, there can be no veridical perception of space. Also, we argue in the phenotypic approach that space perception is an emergent property of affordance perception; they are not different types of perceptions as Cañal-Bruland and van der Kamp presume. Third, affordance perception need not be perfectly accurate, just good enough. Additionally, affordance perception need not be dichotomous; this presumption likely originates in the methodology typically employed to study affordance perception. Finally, I agree with Cañal-Bruland and van der Kamp that joint research efforts will clarify and improve our understanding of these issues.

  6. The Relative Nature of Perception: A Response to Cañal-Bruland and van der Kamp (2015).

    PubMed

    Linkenauger, Sally A

    2015-10-01

    Cañal-Bruland and van der Kamp present an argument about the incommensurate relationship between affordance perception and spatial perception in a criticism of Proffitt and Linkenauger's phenotypic approach to perception. Many of their criticisms are based on a difference in the interpretation of the core ideas underlying the phenotypic approach. The most important of these differences in interpretations concern fundamental assumptions about the nature of the perceptions of size and distance themselves. Extent perception must be relative to the organism; therefore, there can be no veridical perception of space. Also, we argue in the phenotypic approach that space perception is an emergent property of affordance perception; they are not different types of perceptions as Cañal-Bruland and van der Kamp presume. Third, affordance perception need not be perfectly accurate, just good enough. Additionally, affordance perception need not be dichotomous; this presumption likely originates in the methodology typically employed to study affordance perception. Finally, I agree with Cañal-Bruland and van der Kamp that joint research efforts will clarify and improve our understanding of these issues. PMID:27648215

  7. Ascorbate, added after irradiation, reduces the mutant yield and alters the spectrum of CD59- mutations in A(L) cells irradiated with high LET carbon ions

    NASA Technical Reports Server (NTRS)

    Ueno, Akiko; Vannais, Diane; Lenarczyk, Marek; Waldren, Charles A.; Chatterjee, A. (Principal Investigator)

    2002-01-01

    It has been reported that X-ray induced HPRT- mutation in cultured human cells is prevented by ascorbate added after irradiation. Mutation extinction is attributed to neutralization by ascorbate, of radiation-induced long-lived radicals (LLR) with half-lives of several hours. We here show that post-irradiation treatment with ascorbate (5 mM added 30 min after radiation) reduces, but does not eliminate, the induction of CD59- mutants in human-hamster hybrid A(L) cells exposed to high-LET carbon ions (LET of 100 KeV/microm). RibCys, [2(R,S)-D-ribo-1',2',3',4'-Tetrahydroxybutyl]-thiazolidene-4(R)-ca riboxylic acid] (4 mM) gave a similar but lesser effect. The lethality of the carbon ions was not altered by these chemicals. Preliminary data are presented that ascorbate also alters the spectrum of CD59- mutations induced by the carbon beam, mainly by reducing the incidence of small mutations and mutants displaying transmissible genomic instability (TGI), while large mutations are unaffected. Our results suggest that LLR are important in initiating TGI.

  8. Structure, thermodynamic and transport properties of CaAl 2Si 2O 8 liquid. Part I: Molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Spera, Frank J.; Nevins, Dean; Ghiorso, Mark; Cutler, Ian

    2009-11-01

    Molecular dynamics simulations for liquid CaAl 2Si 2O 8 have been carried out at 72 state points spanning ranges in density ( ρ: 2398-4327 kg/m 3), temperature ( T: 3490-6100 K) and pressure ( P: 0.84-120 GPa) relevant to geosystems. The atomic scale structure of the melt is determined by analysis of nearest neighbor coordination statistics as a function of T and P. Dramatic structural change occurs as pressure increases especially for 0 < P <20 GPa at all temperatures. Changes in structure are encapsulated by examining the coordination of Si, Al, Ca and O around oxygen and vice versa. Si and Al change from predominantly fourfold at low- P to dominantly sixfold for P >˜ 20 GPa. Pentahedrally coordinated Si and Al in distorted trigonal bipyramids attain abundance maxima corresponding to ˜60% of total (Si, Al)O n at 3-5 GPa and weakly depend on T. The coordination of Ca by oxygen increases from 7 to 10 for 0 < P < 20 GPa and changes slowly for P > 20 GPa at 3500 K. Similar behavior is seen at 6000 K except that the interval of rapid changes occurs at higher pressure. Oxygen with only one nearest Si or Al neighbor (i.e., non-bridging oxygen, NBO) decreases whereas oxygen with two or three nearest neighbors of Si, Al or Ca increases as pressure increases. Changes in melt structure are reflected in the variation of thermodynamic and transport properties of the liquid. Values of the self-diffusivities of Ca, Al, Si and O are fit to a modified Arrhenian expression and compare well to limited laboratory data. Self-diffusivities are best fit using 'low P' and 'high- P' expressions, identical in form but with different parameters, with activation energies and activation volumes in the range 150-200 kJ/mol and +5 to -1 cm 3/mol, respectively. Green-Kubo calculations for liquid shear viscosity are presented and compare well with limited laboratory results. Application of the Eyring model to determine the characteristic size and number of atoms in the activated cluster based

  9. Phase stability of fcc- and hcp-based intermetallics: The Ti-Al and Cd-Mg systems

    SciTech Connect

    Asta, M.; McCormack, R. . Dept. of Materials Science and Mineral Engineering); van Schilfgaarde, M. ); Ceder, G. . Dept. of Materials Science); de Fontaine, D. . Dept. of Materials Science and Mi

    1992-06-01

    In this paper we summarize results of first-principles phase stability studies of fcc- and hcp-based Ti-Al alloys and of the hcp-based Cd-Mg system. In particular, heats of formation for ordered alloy compounds are calculated with the linear muffin tin orbital method; effective cluster interactions are determined from the results of these calculations and are used to derive thermodynamic properties and composition-temperature phase diagrams.

  10. High-pressure phase relations and thermodynamic properties of CaAl 4Si 2O 11 CAS phase

    NASA Astrophysics Data System (ADS)

    Akaogi, M.; Haraguchi, M.; Yaguchi, M.; Kojitani, H.

    2009-03-01

    Phase relations in CaAl4Si2O11 were examined at 12-23 GPa and 1000-1800 °C by multianvil experiments. A three-phase mixture of grossular, kyanite and corundum is stable below about 13 GPa at 1000-1800 °C. At higher pressure and at temperature below about 1200 °C, a mixture of grossular, stishovite and corundum is stable, indicating the decomposition of kyanite. Above about 1200 °C, CaAl4Si2O11 CAS phase is stable at pressure higher than about 13 GPa. The triple point is placed at 14.7 GPa and 1280 °C. The equilibrium boundary of formation of CAS phase from the mixture of grossular, kyanite and corundum has a small negative slope, and that from the mixture of grossular, stishovite and corundum has a strongly negative slope, while the decomposition boundary of kyanite has a small positive slope. Enthalpies of the transitions were measured by high-temperature drop-solution calorimetry. The enthalpy of formation of CaAl4Si2O11 CAS phase from the mixture of grossular, kyanite and corundum was 139.5 ± 15.6 kJ/mol, and that from the mixture of grossular, stishovite and corundum was 94.2 ± 15.4 kJ/mol. The transition boundaries calculated using the measured enthalpy data were consistent with those determined by the high-pressure experiments. The boundaries in this study are placed about 3 GPa higher in pressure and about 200 °C lower in temperature than those by Zhai and Ito [Zhai, S., Ito, E., 2008. Phase relations of CaAl4Si2O11 at high-pressure and high-temperature with implications for subducted continental crust into the deep mantle. Phys. Earth Planet. Inter. 167, 161-167]. Combining the thermodynamic data measured in this study with those in the literature, dissociation boundary of CAS phase into a mixture of Ca-perovskite, corundum and stishovite and that of grossular into Ca-perovskite plus corundum were calculated to further constrain the stability field of CAS phase. The result suggests that the stability of CAS phase would be limited at the bottom of

  11. Reduced defect density at the CZTSSe/CdS interface by atomic layer deposition of Al2O3

    NASA Astrophysics Data System (ADS)

    Erkan, Mehmet Eray; Chawla, Vardaan; Scarpulla, Michael A.

    2016-05-01

    The greatest challenge for improving the power conversion efficiency of Cu2ZnSn(S,Se)4 (CZTSSe)/CdS/ZnO thin film solar cells is increasing the open circuit voltage (VOC). Probable leading causes of the VOC deficit in state-of-the-art CZTSSe devices have been identified as bulk recombination, band tails, and the intertwined effects of CZTSSe/CdS band offset, interface defects, and interface recombination. In this work, we demonstrate the modification of the CZTSSe absorber/CdS buffer interface following the deposition of 1 nm-thick Al2O3 layers by atomic layer deposition (ALD) near room temperature. Capacitance-voltage profiling and quantum efficiency measurements reveal that ALD-Al2O3 interface modification reduces the density of acceptor-like states at the heterojunction resulting in reduced interface recombination and wider depletion width. Indications of increased VOC resulting from the modification of the heterojunction interface as a result of ALD-Al2O3 treatment are presented. These results, while not conclusive for application to state-of-the-art high efficiency CZTSSe devices, suggest the need for further studies as it is probable that interface recombination contributes to reduced VOC even in such devices.

  12. The influence of Ca-Mg-Al hydrotalcite synthesized from brine water on thermal and mechanical properties of HTlc-EVA composite

    NASA Astrophysics Data System (ADS)

    Karina, Wiwiek; Heraldy, Eddy; Pramono, Edi; Heriyanto, Astuti, Shanti

    2016-02-01

    Ca-Mg-Al hydrotalcite-like compound (Ca-Mg-Al HTlc) was prepared by co-precipitation method using brine water that is well known as the desalination process waste water. The structure of Ca-Mg-Al HTlc was determined by X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) analysis. Ca-Mg-Al HTlc was studied as a non-halogenated filler in ethylene vinyl acetate (EVA) matrix. Composites with different filler concentrations were prepared to evaluate the influence of Ca-Mg-Al HTlc on thermal and mechanical properties of EVA.The presence of Ca-Mg-Al HTlc in the composite has been confirmed by FTIR analysis. Thermal properties of composites show significant reduction of degradation temperature as well as the loading of HTlc in EVA. However, the total enthalpies combustion of composites with 1% and 5% HTlc loadings higher compared to neat EVA. Further, mechanical properties were determined by tensile test. The result shows that tensile strength and elongation at break of composites decrease relatively by Ca-Mg-Al HTlc addition.

  13. Dependence of acoustic property on Al substitution for Ca3Ta(Ga1‑ x Al x )3Si2O14 single crystals

    NASA Astrophysics Data System (ADS)

    Ohashi, Yuji; Arakawa, Mototaka; Kudo, Tetsuo; Yokota, Yuui; Shoji, Yasuhiro; Kurosawa, Shunsuke; Kamada, Kei; Kushibiki, Jun-ichi; Yoshikawa, Akira

    2016-07-01

    The acoustic properties of Ca3Ta(Ga1‑ x Al x )3Si2O14 (CTGASx) were experimentally studied as a function of the Al substitution content x in the ranges from x = 0 to 0.50. Five specimens, X-, Y-, Z-, 35°Y-, and 140°Y-cut, were prepared from each crystal of CTGASx (x = 0, 0.25, and 0.50) grown by the Czochralski technique. Longitudinal wave and shear wave velocities for CTGASx linearly increase with Al content for all propagation directions. Dielectric constants and density were measured and then elastic and piezoelectric constants were determined from the measured velocities for each crystal. The results revealed that all of the constants change linearly with Al content. From the relationship, the constants for CTAS (x = 1) were estimated. Calculations of the velocities using the determined constants also suggested that the maximum electromechanical coupling factor k 2 for the slow shear wave mode propagating along the rotated Y-axis direction of CTAS was improved to 4.42% compared with 3.83% for CTGS, owing to the Al substitution effect.

  14. Ca,Al-rich inclusions, amoeboid olivine aggregates, and Al-rich chondrules from the unique carbonaceous chondrite Acfer 094: I. mineralogy and petrology

    NASA Astrophysics Data System (ADS)

    Krot, Alexander N.; Fagan, Timothy J.; Keil, Klaus; McKeegan, Kevin D.; Sahijpal, Sandeep; Hutcheon, Ian D.; Petaev, Mikhail I.; Yurimoto, Hisayoshi

    2004-05-01

    Based on their mineralogy and petrography, ˜200 refractory inclusions studied in the unique carbonaceous chondrite, Acfer 094, can be divided into corundum-rich (0.5%), hibonite-rich (1.1%), grossite-rich (8.5%), compact and fluffy Type A (spinel-melilite-rich, 50.3%), pyroxene-anorthite-rich (7.4%), and Type C (pyroxene-anorthite-rich with igneous textures, 1.6%) Ca,Al-rich inclusions (CAIs), pyroxene-hibonite spherules (0.5%), and amoeboid olivine aggregates (AOAs, 30.2%). Melilite in some CAIs is replaced by spinel and Al-diopside and/or by anorthite, whereas spinel-pyroxene assemblages in CAIs and AOAs appear to be replaced by anorthite. Forsterite grains in several AOAs are replaced by low-Ca pyroxene. None of the CAIs or AOAs show evidence for Fe-alkali metasomatic or aqueous alteration. The mineralogy, textures, and bulk chemistry of most Acfer 094 refractory inclusions are consistent with their origin by gas-solid condensation and may reflect continuous interaction with SiO and Mg of the cooling nebula gas. It appears that only a few CAIs experienced subsequent melting. The Al-rich chondrules (ARCs; >10 wt% bulk Al 2O 3) consist of forsteritic olivine and low-Ca pyroxene phenocrysts, pigeonite, augite, anorthitic plagioclase, ± spinel, FeNi-metal, and crystalline mesostasis composed of plagioclase, augite and a silica phase. Most ARCs are spherical and mineralogically uniform, but some are irregular in shape and heterogeneous in mineralogy, with distinct ferromagnesian and aluminous domains. The ferromagnesian domains tend to form chondrule mantles, and are dominated by low-Ca pyroxene and forsteritic olivine, anorthitic mesostasis, and Fe,Ni-metal nodules. The aluminous domains are dominated by anorthite, high-Ca pyroxene and spinel, occasionally with inclusions of perovskite; have no or little FeNi-metal; and tend to form cores of the heterogeneous chondrules. The cores are enriched in bulk Ca and Al, and apparently formed from melting of CAI

  15. Differential Phenotypic and Functional Profiles of TcCA-2 -Specific Cytotoxic CD8+ T Cells in the Asymptomatic versus Cardiac Phase in Chagasic Patients

    PubMed Central

    Egui, Adriana; Thomas, M. Carmen; Carrilero, Bartolomé; Segovia, Manuel; Alonso, Carlos; Marañón, Concepción; López, Manuel Carlos

    2015-01-01

    It has been reported that the immune response mediated by T CD8+ lymphocytes plays a critical role in the control of Trypanosoma cruzi infection and that the clinical symptoms of Chagas disease appear to be related to the competence of the CD8+ T immune response against the parasite. Herewith, in silico prediction and binding assays on TAP-deficient T2 cells were used to identify potential HLA-A*02:01 ligands in the T. cruzi TcCA-2 protein. The TcCA-2-specific CD8+ T cells were functionality evaluated by Granzyme B and cytokine production in peripheral blood mononuclear cells (PBMC) from Chagas disease patients stimulated with the identified HLA-A*02:01 peptides. The specific cells were phenotypically characterized by flow cytometry using several surface markers and HLA-A*02:01 APC-labeled dextramer loaded with the peptides. In the T. cruzi TcCA-2 protein four T CD8+ epitopes were identified which are processed and presented during Chagas disease. Interestingly, a differential cellular phenotypic profile could be correlated with the severity of the disease. The TcCA-2-specific T CD8+ cells from patients with cardiac symptoms are mainly effector memory cells (TEM and TEMRA) while, those present in the asymptomatic phase are predominantly naive cells (TNAIVE). Moreover, in patients with cardiac symptoms the percentage of cells with senescence features is significantly higher than in patients at the asymptomatic phase of the disease. We consider that the identification of these new class I-restricted epitopes are helpful for designing biomarkers of sickness pathology as well as the development of immunotherapies against T. cruzi infection. PMID:25816096

  16. Super Smooth Modification of Al2O3 Ceramic Substrate by High Temperature Glaze of CaO-Al2O3-SiO2 System

    NASA Astrophysics Data System (ADS)

    Zhang, Jihua; Zhen, Shanxue; Yang, Lijun; Lou, Feizhi; Chen, Hongwei; Yang, Chuanren

    2011-01-01

    The rough surface of ceramic substrate is an obstacle for the scale down of line-width for thin film passive integrated devices (PID). In this paper, a modification method for Al2O3 ceramic substrate with super smooth in surface was proposed. Coating a layer of CaO-Al2O3-SiO2 (CAS) glass was performed to flat the rough surface of alumina substrate by sol-gel method. It was found that addition of 0.06% V2O5 can inhibit the recrystallization of the glaze. The root-mean-square (RMS) roughness of the glazed substrates reached a surprising flatness as small as 0.5 nm, and its melting temperature is higher than 1300 °C. This substrate with super flatness and high temperature endurance may be promising for high performance thin film devices.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  18. Crystal characterization and optical spectroscopy of Ti{sup 3+}-doped CaGdAlO{sub 4} crystals

    SciTech Connect

    Kodama, N.; Yamaga, M.

    1998-01-01

    CaGdAlO{sub 4} crystals doped with Ti ions were grown using the Czochralski technique in a reducing atmosphere in order to convert the valence of Ti to trivalence. The fluorescence of the {sup 2}E{r_arrow}{sup 2}T{sub 2} transition of Ti{sup 3+} in the crystals shows a broad band with a peak at 535 nm excited with the light of 410 nm in the optical absorption band at room temperature because of a strong electron-phonon coupling of the {sup 2}E excited state. The Ti{sup 3+} fluorescence is influenced in intensity by O{sup 2{minus}} vacancies at the ligands of the Ti{sup 3+} octahedra along the c axis, which are easily produced in a reducing atmosphere. The x-ray crystal analyses and the polarization of the optical absorption and fluorescence spectra deduce the energy levels and wave functions of the ground and excited states of Ti{sup 3+} in CaGdAlO{sub 4}. The peak energy of the fluorescence band shifts to higher energy as increasing excitation energy in the absorption band. The linear dependence of the fluorescence-peak energy on the excitation energy shows that the fluorescence is inhomogeneously broadened by a random distribution of Ca{sup 2+} and Gd{sup 3+} ions in the disordered lattice.

  19. Thermodynamics and Structure of CaO-Al2O3-3 Mass Pct B2O3 Slag at 1773 K (1500 °C)

    NASA Astrophysics Data System (ADS)

    Shu, Qifeng; Li, Pengfei; Zhang, Xiang; Chou, Kuochih

    2016-08-01

    Activity values of Al2O3 in CaO-Al2O3-B2O3 systems at 1773 K (1500 °C) were determined experimentally using a gas-copper-slag equilibrium technique. The oxygen partial pressure was controlled by C/CO equilibrium. A negative deviation from ideality was found in measured activity of Al2O3. The activity coefficient of Al2O3 decreases with the increase of CaO/Al2O3 ratio. To interpret the variation of Al2O3 activity with composition, structures of CaO-Al2O3-B2O3 glassy slag were investigated by using Raman spectroscopy. It was found that the number of bridging oxygen decreases with increasing CaO/Al2O3 ratio. With increase of CaO content, the aluminate network was gradually depolymerized, which corresponds to the decrease of the activity coefficient of Al2O3.

  20. Fuel mixture approach for solution combustion synthesis of Ca{sub 3}Al{sub 2}O{sub 6} powders

    SciTech Connect

    Ianos, Robert Lazau, Ioan; Pacurariu, Cornelia; Barvinschi, Paul

    2009-07-15

    Single-phase 3CaO.Al{sub 2}O{sub 3} powders were prepared via solution combustion synthesis using a fuel mixture of urea and {beta}-alanine. The concept of using this fuel mixture comes from the individual reactivity of calcium nitrate and aluminum nitrate with respect to urea and {beta}-alanine. It was proved that urea is the optimum fuel for Al(NO{sub 3}){sub 3} whereas {beta}-alanine is the most suitable fuel for Ca(NO{sub 3}){sub 2}. X-ray diffraction and thermal analysis investigations revealed that heating at 300 deg. C the precursor mixture containing the desired metal nitrates, urea and {beta}-alanine triggers a vigorous combustion reaction, which yields single-phase nanocrystalline 3CaO.Al{sub 2}O{sub 3} powder (33.3 nm). In this case additional annealing was no longer required. The use of a single fuel failed to ensure the formation of 3CaO.Al{sub 2}O{sub 3} directly from the combustion reaction. After annealing at 900 deg. C for 1 h, the powders obtained by using a single fuel (urea or {beta}-alanine) developed a phase composition comprising of 3CaO.Al{sub 2}O{sub 3}, 12CaO.7Al{sub 2}O{sub 3} and CaO.

  1. CaMn2Al10: Itinerant Mn magnetism on the verge of magnetic order

    SciTech Connect

    Steinke, L.; Simonson, J. W.; Yin, W. -G.; Smith, G. J.; Kistner-Morris, J. J.; Zellman, S.; Puri, A.; Aronson, M. C.

    2015-07-24

    We report the discovery of CaMn2Al10, a metal with strong magnetic anisotropy and moderate electronic correlations. Magnetization measurements find a Curie-Weiss moment of 0.83μB/Mn, significantly reduced from the Hund's rule value, and the magnetic entropy obtained from specific heat measurements is correspondingly small, only ≈ 9% of Rln2. These results imply that the Mn magnetism is highly itinerant, a conclusion supported by density functional theory calculations that find strong Mn-Al hybridization. Consistent with the layered nature of the crystal structure, the magnetic susceptibility χ is anisotropic below 20 K, with a maximum ratio of χ[010][001] ≈ 3.5. A strong power-law divergence χ(T) ~ T–1.2 below 20 K implies incipient ferromagnetic order, an Arrott plot analysis of the magnetization suggests a vanishing low Curie temperature TC ~ 0. Our experiments indicate that CaMn2Al10 is a rare example of a system where the weak and itinerant Mn-based magnetism is poised on the verge of order.

  2. Spectroscopic properties of UV active medium Ce3+:LiSr0.8Ca0.2AlF6

    NASA Astrophysics Data System (ADS)

    Nizamutdinov, A. S.; Shavelev, A. A.; Marisov, M. A.; Semashko, V. V.

    2016-02-01

    The aim of this work is phase composition and near UV spectroscopic studies of UV active media in fluoride crystals with colquiriite structure, such as Ce3+:LiSr0.8Ca0.2AlF6. Colquiriite structure mixed crystals show higher segregation coefficient of Ce3+ activator ions than common LiCaAlF6 hosts. An important result is based on the fact that this enhancement was achieved for two types of Ce3+ centers in a multisite Ce:LiSr0.8Ca0.2AlF6 system. Thus, it provides a higher gain coefficient for the 5d-4f transitions of Ce3+ ions and it spans a wider continuous wavelength tuning range between 280 and 320 nm for tunable Ce:LiSr0.8Ca0.2AlF6 laser systems.

  3. Cross sections for He and Ne isotopes in natural Mg, Al, and Si, He isotopes in CaF2, Ar isotopes in natural Ca, and radionuclides in natural Al, Si, Ti, Cr, and stainless steel induced by 12- to 45-MeV protons

    NASA Technical Reports Server (NTRS)

    Walton, J. R.; Heymann, D.; Yaniv, A.; Edgerley, D.; Rowe, M. W.

    1976-01-01

    Stacks of thin Mg, Al, Si, Ca, CaF2, Ti, and stainless steel foils were bombarded in twelve irradiations by a variable energy cyclotron. Cross sections are reported for He and Ne in natural Mg, Al, and Si, and for He in CaF2, and for Ar in natural Ca, as determined from mass spectrometer analysis of the inert gases. In addition, cross sections of Na-22 in natural Al and Si, of V-48 in natural Ti, and of Cr-51, Mn-52, and Co-57 in stainless steel are reported. From these were deduced Cr-51 and Mn-52 cross sections in natural Cr.

  4. New acoustic velocity measurements on CaO-MgO-Al2O3-SiO2 liquids: Reevaluation of the volume and compressibility of CaMgSi2O6-CaAl2Si2O8 liquids to 25 GPa

    NASA Astrophysics Data System (ADS)

    Ai, Yuhui; Lange, Rebecca A.

    2008-04-01

    Relaxed sound speed measurements on 12 liquids in the CaO-MgO-Al2O3-SiO2 (CMAS) system have been performed from 1410 to 1620°C at 1 bar with a frequency sweep acoustic interferometer. In all liquids, the sound speeds either decrease or remain constant with increasing temperature. These data are combined with those in the literature to calibrate models for βT and (∂V/∂P)T as a function of composition and temperature for CMAS liquids. CaO is the only oxide component that contributes to the temperature dependence of compressibility. The new compressibility models permit the bulk modulus (KT,0) of CaMgSi2O6 (Di), CaAl2Si2O8 (An), and the Di64-An36 eutectic liquid to be directly obtained. These results are used to uniquely constrain values for the pressure dependence of the bulk modulus (K0' = dK0/dP) in a third-order Birch-Murnaghan equation of state (EOS) for these three liquids from shock wave data in the literature. The revised K0' value is 6.8 (versus 6.9) for CaMgSi2O6 liquid, 4.7 (versus 5.3) for CaAl2Si2O8 liquid, and 5.6 (versus 4.85) for Di64-An36 liquid. Information on both KT,0 and K0' allows the density and compressibility for each of these three liquids to be calculated as a function of pressure to 25 GPa. Both the molar volume and isothermal compressibility of CaMgSi2O6-CaAl2Si2O8 liquids mix ideally between 0 and 25 GPa. The dominant mechanism of compression at low pressure (0-5 GPa) for all three liquids (CaMgSi2O6, CaAl2Si2O8, and the Di64-An36 eutectic) is topological, whereas gradual Al/Si coordination change plays an increasingly important role at higher pressure as topological mechanisms of compression are diminished.

  5. Efficient Yb³⁺:CaGdAlO₄ bulk and femtosecond-laser-written waveguide lasers.

    PubMed

    Hasse, Kore; Calmano, Thomas; Deppe, Bastian; Liebald, Christoph; Kränkel, Christian

    2015-08-01

    We report on, to the best of our knowledge, the first fs-laser-written waveguide laser in Yb3+:CaGdAlO4 (Yb:CALGO). With Yb:CALGO crystals grown in our labs, we obtained a slope efficiency of 69% and up to 2.4 W of continuous wave (cw) output power in a waveguide-laser configuration. Moreover, bulk laser experiments with Yb:CALGO were performed, and slope efficiencies up to 73%, optical-to-optical efficiencies of 65%, and maximum cw output powers of 3.3 W were reached. These are the highest efficiencies in the laser configuration with Yb:CALGO.

  6. Synthesis of a novel green fluorescent material Ca3Al2O6:Tb3+ based on a layered double hydroxide precursor

    NASA Astrophysics Data System (ADS)

    Gao, Xiaorui; Jiang, Kangle; Hao, Yongjing; Chang, Tao; Yin, Yaobing

    2015-08-01

    A novel green light emitting material, Ca3Al2O6:Tb3+ was synthesized by calcination of a terbium doped Ca/Al layered double hydroxide precursor at 1350°C. The precursor was prepared by coprecipitation from metal nitrates with sodium hydroxide. The material shows characteristic green emission at 543 nm when excited with 266 nm UV source. The photoluminescence intensity reaches its maximum at Tb3+ concentration of 0.5 mol %.

  7. Syntheses and luminescent properties of CaAl2Si2O8:Eu2+, Mn2+ phosphors for white LED

    NASA Astrophysics Data System (ADS)

    Kwon, Sook Hyun; Moon, Byung Kee; Choi, Byung Chun; Jeong, Jung Hyun; Kim, Jung Hwan

    2016-01-01

    Aluminosilicate-based luminescent materials, a series of CaAl2Si2O8:Eu2+ samples were prepared by using a solid-state reaction method. The X-ray diffraction patterns of the samples confirmed their triclinic structure after annealing at 1100 °C. The excitation spectra of CaAl2Si2O8:Eu2+ exhibited a broad band ranging between 220 to 420 nm with a point peak at a longer wavelength. Moreover, a shift in the broad band was also recorded with increasing Eu2+ concentration. The emission spectrum of CaAl2Si2O8:Eu2+ consists of a broad band from 390 to 550 nm with a maximum intensity at about 438 nm, which can be ascribed to the electric-dipole-allowed 4f65d1-8S7/2(4f7) transition of the Eu2+ ions. A series of Eu2+ and Mn2+ co-activated CaAl2Si2O8 samples were synthesized at 1400 °C. The CaAl2Si2O8:Eu2+, Mn2+ samples had a wide emission band ranging from blue to yellow and peaking at 438 and 550 nm under an excitation wavelength of 352 nm. The PL spectrum of the CaAl2Si2O8:Eu2+, Mn2+ samples reveal an effective energy transfer from Eu2+ to Mn2+ in CaAl2Si2O8. By utilizing the principle of energy transfer, we also demonstrated that with appropriate tuning of the activator content, CaAl2Si2O8:Eu2+, Mn2+ phosphors exhibit great potential as a phosphor for white-light-emitting diodes.

  8. Influence of Ca/Mg ratio on phytoextraction properties of Salix viminalis I. The effectiveness of Cd, Cu, Pb, and Zn bioaccumulation and plant growth.

    PubMed

    Mleczek, Mirosław; Kozlowska, Monika; Kaczmarek, Zygmunt; Chadzinikolau, Tamara; Golinski, Piotr

    2012-01-01

    Phytoremediation and its efficiency--influenced by several factors-is prime concern in reduction of environment contamination with heavy metals. The aim of the study was to estimate in controlled conditions--in relation to the natural Ca/Mg ratio 4:1--the influence of different Ca/Mg ratios (1:1/4, 20:1, 1:10) on selected heavy metals (Cd, Cu, Pb, and Zn) accumulation efficiency shown by three morphological parts of Salix viminalis 'Cinamomea' (cane bark, shoots and roots). Accumulation of heavy metals in experimental conditions was significantly Ca/Mg ratio dependent, and occurred in the following order: 1:10 > 4:1 > 20:1 > 1:1/4. The highest accumulation under 0.5 mM solutions (as compared to 0.1 mM) was noted for copper and zinc, and the lowest for cadmium. Biometric parameters of Salix viminalis cuttings revealed the highest biomass productivity under 20:1 and 4:1 Ca/Mg ratios. In the case of shoot length increase, both metal concentration and kind of metal present in the solution were important. The results indicate that higher calcium ion concentration in solution (Ca/Mg 20:1) stimulates Salix viminalis growth by 3 fold when compared to other Ca/Mg ratio. It can be an important factor in remediation of the environment with this plant.

  9. Structural, vibrational and luminescence properties of the (1−x)CaWO{sub 4}−xCdWO{sub 4} system

    SciTech Connect

    Taoufyq, A.; Guinneton, F.; Valmalette, J-C.; Arab, M.; Benlhachemi, A.; Bakiz, B.; Villain, S.; and others

    2014-11-15

    In the present work, we investigate the structural, microstructural, vibrational and luminescence properties of the system (1−x)CaWO{sub 4}−xCdWO{sub 4} with x ranging between 0 and 1. Polycrystalline samples were elaborated using a coprecipitation technique followed by thermal treatment at 1000 °C. The samples were then characterized using X-ray diffraction, scanning electron microscopy, Raman spectroscopy and luminescence analyses. X-ray diffraction profile analyses using Rietveld method showed that two kinds of solid solutions Ca{sub 1−x}Cd{sub x}WO{sub 4} having scheelite and wolframite structures, with respectively tetragonal and monoclinic crystal cells, were observed, with a biphasic system for compositions x=0.6 and 0.7. The scanning electron microscopy experiments showed a complex evolution of morphologies and crystallite sizes as x increased. The vibration modes of Raman spectra were characteristic of composition-dependent disordered solid solutions with decreasing wavenumbers as x increased. Luminescence experiments were performed under UV-laser light irradiation. The energies of emission bands increased linearly with cadmium composition x. The integrated intensity of luminescence reached a maximum value for the substituted wolframite phase with composition x=0.8. - Graphical abstract: Luminescence on UV excitation (364.5 nm) of (1−x)CaWO{sub 4−x}CdWO{sub 4} system, elaborated from coprecipitation technique at 1000 °C, with 0Ca{sub 1−x}Cd{sub x}WO{sub 4} polycrystalline phases with 0≤x≤0.5. (b) Maximum of luminescence intensity for the composition x=0.8. - Highlights: • Solid solutions Ca{sub 1−x}Cd{sub x}WO{sub 4} are elaborated from coprecipitation technique. • The structures of two types of solid solutions are refined using Rietveld method. • A maximum of luminescence is obtained for an intermediate composition x=0.8.

  10. High Tc superconductivity in the triple-perovskite La-rare earth or alkali metal-Ba-Ca-Mg or Cd-Cu-oxide system. Technical report, January-December 1996

    SciTech Connect

    Tauber, A.; Tidrow, S.C.; Pierce, D.; Eckart, D.W.

    1997-03-01

    Bulk targets of compounds in the system La(3{minus}z)Me(z)Ba3Ca(1{minus}v)Nc{sub v}Cu7O(16+v) where Me=rare earth or Na and Nc=Mg or Cd were prepared by solid state reactions. They were employed to deposit by pulse laser deposition thin films of the superconductor on single crystal substrates of LaAlO3, LSAT, and GGG. Phase relationships and orientation relationships were obtained from diffractometer scans. All compounds exhibited a (001) relationship with all substrates. Lattice parameters, transition temperatures and widths are reported for each superconducting compound. All substituted compounds were superconducting but no increase in Tc was observed for any. All thin films heated to 750 deg C desorbed little oxygen compared to YBCO.

  11. Crustal structure of the Pannonian Basin: The AlCaPa and Tisza Terrains and the Mid-Hungarian Zone

    NASA Astrophysics Data System (ADS)

    Hetényi, György; Ren, Yong; Dando, Ben; Stuart, Graham W.; Hegedűs, Endre; Kovács, Attila Csaba; Houseman, Gregory A.

    2015-04-01

    The Pannonian Basin of Central Europe is one of the key examples of Miocene continental extension that is easily accessible to surface seismological investigation. It comprises two major crustal blocks: AlCaPa and Tisza which abut along a poorly understood structure referred to as the Mid-Hungarian Zone (MHZ), the whole being surrounded by the arc of the Carpathian Mountains, the Alps and the Dinarides. Using data from the CBP (Carpathian Basins Project) temporary broadband seismic array of 46 stations deployed across the western Pannonian Basin in 2006-2007, we calculated receiver functions that constrain the variation of crustal thickness across the basin and derive a map of Moho depth across a NW-SE oriented swath about 450 km long and 75 km wide. The measured Moho depths show no significant change in crustal thickness between AlCaPa and Tisza terrains, but the Moho is not or very weakly imaged along a ca. 40 km wide strip centred on the MHZ. Moho depths within the Pannonian Basin are typically in the range 25-30 km, and increase toward the periphery of the basin. Our measurements are generally consistent with earlier VP models from controlled-source seismic surveys and recent VS models determined by tomographic analysis of ambient noise signals. The lack of a sharp Moho image beneath the MHZ suggests that the crust-mantle boundary in that zone may consist of a gradual increase in velocity with depth. The relatively constant crustal thickness across the two domains of the Pannonian Basin suggests that thinning to the same final state is controlled thermally. This structural characteristic seems to be governed by a large-scale balance of gravitational potential energy that is insensitive to the separate prior histories of the two regions.

  12. Synthesis of Compositionally Defined Single-Crystalline Eu 3+ -Activated Molybdate–Tungstate Solid-Solution Composite Nanowires and Observation of Charge Transfer in a Novel Class of 1D CaMoO 4 –CaWO 4 :Eu 3+ –0D CdS/CdSe QD Nanoscale Heterostructures

    DOE PAGES

    Han, Jinkyu; McBean, Coray; Wang, Lei; Jaye, Cherno; Liu, Haiqing; Fischer, Daniel A.; Wong, Stanislaus S.

    2015-02-10

    As a first step, we have synthesized and optically characterized a systematic series of one-dimensional (1D) single-crystalline Eu³⁺-activated alkaline-earth metal tungstate/molybdate solid solution composite CaW₁₋xMoxO₄ (0 ≤ ‘x’ ≤ 1) nanowires of controllable chemical composition using a modified template-directed methodology under ambient room-temperature conditions. Extensive characterization of the resulting nanowires has been performed using X-ray diffraction, electron microscopy, and optical spectroscopy. The crystallite size and single crystallinity of as-prepared 1D CaW₁₋xMoxO₄: Eu³⁺ (0 ≤ ‘x’ ≤ 1) solid solution composite nanowires increase with increasing Mo component (‘x’). We note a clear dependence of luminescence output upon nanowire chemical composition withmore » our 1D CaW₁₋xMoxO₄: Eu³⁺ (0 ≤ ‘x’ ≤ 1) evincing the highest photoluminescence (PL) output at ‘x’ = 0.8, amongst samples tested. Subsequently, coupled with either zero-dimensional (0D) CdS or CdSe quantum dots (QDs), we successfully synthesized and observed charge transfer processes in 1D CaW1-xMoxO4: Eu3+ (‘x’ = 0.8) – 0D QD composite nanoscale heterostructures. Our results show that CaW₁₋xMoxO₄: Eu³⁺ (‘x’ = 0.8) nanowires give rise to PL quenching when CdSe QDs and CdS QDs are anchored onto the surfaces of 1D CaW₁₋xMoxO₄: Eu³⁺ nanowires. The observed PL quenching is especially pronounced in CaW₁₋xMoxO₄: Eu³⁺ (‘x’ = 0.8) – 0D CdSe QD heterostructures. Conversely, the PL output and lifetimes of CdSe and CdS QDs within these heterostructures are not noticeably altered as compared with unbound CdSe and CdS QDs. The difference in optical behavior between 1D Eu³⁺ activated tungstate and molybdate solid solution nanowires and the semiconducting 0D QDs within our heterostructures can be correlated with the relative positions of their conduction and valence energy band levels. We propose that

  13. Synthesis of Compositionally Defined Single-Crystalline Eu 3+ -Activated Molybdate–Tungstate Solid-Solution Composite Nanowires and Observation of Charge Transfer in a Novel Class of 1D CaMoO 4CaWO 4 :Eu 3+ –0D CdS/CdSe QD Nanoscale Heterostructures

    SciTech Connect

    Han, Jinkyu; McBean, Coray; Wang, Lei; Jaye, Cherno; Liu, Haiqing; Fischer, Daniel A.; Wong, Stanislaus S.

    2015-02-10

    As a first step, we have synthesized and optically characterized a systematic series of one-dimensional (1D) single-crystalline Eu³⁺-activated alkaline-earth metal tungstate/molybdate solid solution composite CaW₁₋xMoxO₄ (0 ≤ ‘x’ ≤ 1) nanowires of controllable chemical composition using a modified template-directed methodology under ambient room-temperature conditions. Extensive characterization of the resulting nanowires has been performed using X-ray diffraction, electron microscopy, and optical spectroscopy. The crystallite size and single crystallinity of as-prepared 1D CaW₁₋xMoxO₄: Eu³⁺ (0 ≤ ‘x’ ≤ 1) solid solution composite nanowires increase with increasing Mo component (‘x’). We note a clear dependence of luminescence output upon nanowire chemical composition with our 1D CaW₁₋xMoxO₄: Eu³⁺ (0 ≤ ‘x’ ≤ 1) evincing the highest photoluminescence (PL) output at ‘x’ = 0.8, amongst samples tested. Subsequently, coupled with either zero-dimensional (0D) CdS or CdSe quantum dots (QDs), we successfully synthesized and observed charge transfer processes in 1D CaW1-xMoxO4: Eu3+ (‘x’ = 0.8) – 0D QD composite nanoscale heterostructures. Our results show that CaW₁₋xMoxO₄: Eu³⁺ (‘x’ = 0.8) nanowires give rise to PL quenching when CdSe QDs and CdS QDs are anchored onto the surfaces of 1D CaW₁₋xMoxO₄: Eu³⁺ nanowires. The observed PL quenching is especially pronounced in CaW₁₋xMoxO₄: Eu³⁺ (‘x’ = 0.8) – 0D CdSe QD heterostructures. Conversely, the PL output and lifetimes of CdSe and CdS QDs within these heterostructures are not noticeably altered as compared with unbound CdSe and CdS QDs. The difference in optical behavior between 1D Eu³⁺ activated tungstate and molybdate solid solution nanowires and the semiconducting 0D QDs within our

  14. Host lattice materials in the system Ca3N2-AlN-Si3N4 for white light emitting diode

    NASA Astrophysics Data System (ADS)

    Uheda, K.; Hirosaki, N.; Yamamoto, H.

    2006-09-01

    New host lattice materials whose red phosphors for white LEDs have been investigated in the ternary system Ca3N2-AlN-Si3N4, just as Ca2Si5N8 and CaSiN2:Eu were found in the binary system Ca3N2-Si3N4. A new red phosphor of CaAlSiN3:Eu which is effectively excited by blue-GaN and near UV-GaInN LED chips has been synthesized at 1600 °C for 2 h and subsequently at 1800 °C for 2 h under nitrogen pressure of 1 MPa. The host-compound has an orthorhombic structure with the space group Cmc21 (No. 36), which is isotypic with LiSi2N3 and NaSi2N3. The red phosphor showed the emission peak around 650 nm which was assinged to 5d 4f of Eu2+ ion, and its color coordinates were estimated to be 0.667 and 0.327. The optimum concentration of Eu2+ ion was 1.6 mol%. The phosphor also had a high chemical stability, high quantum output, and especially a good thermal property compared to the other phosphors, Ca2Si5N8:Eu2+ and CaSiN2:Eu2+. CaAlSiN3:Eu2+ maintained 83% of the initial efficiency above 150 °C.

  15. Toxic Metals (Pb and Cd) and Their Respective Antagonists (Ca and Zn) in Infant Formulas and Milk Marketed in Brasilia, Brazil

    PubMed Central

    De Castro, Clarissa S. P.; Arruda, Andréa F.; Da Cunha, Leandro R.; SouzaDe, Jurandir R.; Braga, Jez W. B.; Dórea, José G.

    2010-01-01

    In non-ideal scenarios involving partial or non-breastfeeding, cow’s milk-based dairy products are mainstream in infant feeding. Therefore, it is important to study the concentrations of potentially neurotoxic contaminants (Pb and Cd) and their respective counteracting elements (Ca and Zn) in infant dairy products. Fifty-five brands of infant formulas and milk sold in Brasilia, Brazil were analyzed. The dairy products came from areas in the central-west (26%), southeast (29%) and south of Brazil (36%) extending as far as Argentina (7%) and the Netherlands (2%). For toxic Pb and Cd, median concentrations in powdered samples were 0.109 mg/kg and 0.033 mg/kg, respectively; in fluid samples median Pb concentration was 0.084 mg/kg, but median Cd concentration was below the limit of detection and overall values were below reference safety levels. However, 62% of these samples presented higher Pb concentration values than those established by FAO/WHO. Although the inverse correlation between Cd and Zn (Spearman r = −0.116; P = 0.590) was not statistically significant, the positive correlation between Ca and Pb was (Spearman r = 0.619; P < 0.0001). Additionally, there was a significant correlation between Pb and Cd. Furthermore, the study also revealed that provision of the essential trace element Zn in infant formulas can provide adequate amounts of the recommended daily requirements. Infant formulas and milk sold for consumption by infants and children can be an efficient tool to monitor neurotoxic metal risk exposure among young children. PMID:21139877

  16. Probing structure-induced optical behavior in a new class of self-activated luminescent 0D/1D CaWO₄ metal oxide – CdSe nanocrystal composite heterostructures

    SciTech Connect

    Han, Jinkyu; McBean, Coray; Wang, Lei; Hoy, Jessica; Jaye, Cherno; Liu, Haiqing; Li, Zhuo-Qun; Sfeir, Matthew Y.; Fischer, Daniel A.; Taylor, Gordon T.; Misewich, James A.; Wong, Stanislaus S.

    2015-01-30

    In this report, we synthesize and characterize the structural and optical properties of novel heterostructures composed of (i) semiconducting nanocrystalline CdSe quantum dot (QDs) coupled with (ii) both one and zero-dimensional (1D and 0D) motifs of self-activated luminescence CaWO₄ metal oxides. Specifically, ~4 nm CdSe QDs have been anchored onto (i) high-aspect ratio 1D nanowires, measuring ~230 nm in diameter and ~3 μm in length, as well as onto (ii) crystalline 0D nanoparticles (possessing an average diameter of ~ 80 nm) of CaWO₄ through the mediation of 3-mercaptopropionic acid (MPA) as a connecting linker. Composite formation was confirmed by complementary electron microscopy and spectroscopy (i.e. IR and Raman) data. In terms of luminescent properties, our results show that our 1D and 0D heterostructures evince photoluminescence (PL) quenching and shortened PL lifetimes of CaWO₄ as compared with unbound CaWO₄. We propose that a photo-induced electron transfer process occurs from CaWO₄ to CdSe QDs, a scenario which has been confirmed by NEXAFS measurements and which highlights a decrease in the number of unoccupied orbitals in the conduction bands of CdSe QDs. By contrast, the PL signature and lifetimes of MPA-capped CdSe QDs within these heterostructures do not exhibit noticeable changes as compared with unbound MPA-capped CdSe QDs. The striking difference in optical behavior between CaWO₄ nanostructures and CdSe QDs within our heterostructures can be correlated with the relative positions of their conduction and valence energy band levels. In addition, the PL quenching behaviors for CaWO₄ within the heterostructure configuration were examined by systematically varying (i) the quantities and coverage densities of CdSe QDs as well as (ii) the intrinsic morphology (and by extension, the inherent crystallite size) of CaWO₄ itself.

  17. Vitality and chemistry of roots of red spruce in forest floors of stands with a gradient of soil Al/Ca ratios in the northeastern United States

    USGS Publications Warehouse

    Wargo, P.M.; Vogt, K.; Vogt, D.; Holifield, Q.; Tilley, J.; Lawrence, G.; David, M.

    2003-01-01

    Number of living root tips per branch, percent dead roots, percent mycorrhizae and mycorrhizal morphotype, response of woody roots to wounding and colonization by fungi, and concentrations of starch, soluble sugars, phenols, percent C and N and C/N ratio, and Al Ca, Fe, K, Mg, Mn, and P were measured for 2 consecutive years in roots of red spruce (Picea rubens Sarg.) in stands in the northeastern United States (nine in 1993 and two additional in 1994) dominated by red spruce and with a gradient of forest floor exchangeable Al/Ca ratios. Root vitality was measured for nonwoody and coarse woody roots; chemical variables were measured for nonwoody (<1 mm), fine woody (1 to <2 mm), and coarse woody (2 to <5 mm) roots. There were significant differences among sites for all variables, particularly in 1993, although few were related to the Al/Ca ratio gradient. Percent mycorrhizae decreased, while some morphotypes increased or decreased as the Al/Ca ratio increased. In nonwoody roots, N increased as the Al/Ca ratio increased. Most sampled trees appeared to be in good or fair health, suggesting that an adverse response of these root variables to high Al concentrations may be apparent only after a significant change in crown health.

  18. Mechanical Properties and Fracture Behaviors of the As-Extruded Mg-5Al-3Ca Alloys Containing Yttrium at Elevated Temperature.

    PubMed

    Son, Hyeon-Taek; Kim, Yong-Ho; Kim, Taek-Soo; Lee, Seong-Hee

    2016-02-01

    Effects of yttrium (Y) addition on mechanical properties and fracture behaviors of the as-extruded Mg-Al-Ca based alloys at elevated temperature were investigated by a tensile test. After hot extrusion, the average grain size was refined by Y addition and eutectic phases were broken down into fine particles. Y addition to Mg-5Al-3Ca based alloy resulted in the improvement of strength and ductility at elevated temperature due to fine grain and suppression of grain growth by formation of thermally stable Al2Y intermetallic compound.

  19. Mechanical Properties and Fracture Behaviors of the As-Extruded Mg-5Al-3Ca Alloys Containing Yttrium at Elevated Temperature.

    PubMed

    Son, Hyeon-Taek; Kim, Yong-Ho; Kim, Taek-Soo; Lee, Seong-Hee

    2016-02-01

    Effects of yttrium (Y) addition on mechanical properties and fracture behaviors of the as-extruded Mg-Al-Ca based alloys at elevated temperature were investigated by a tensile test. After hot extrusion, the average grain size was refined by Y addition and eutectic phases were broken down into fine particles. Y addition to Mg-5Al-3Ca based alloy resulted in the improvement of strength and ductility at elevated temperature due to fine grain and suppression of grain growth by formation of thermally stable Al2Y intermetallic compound. PMID:27433675

  20. Thermodynamics of Complex Sulfide Inclusion Formation in Ca-Treated Al-Killed Structural Steel

    NASA Astrophysics Data System (ADS)

    Guo, Yin-tao; He, Sheng-ping; Chen, Gu-jun; Wang, Qian

    2016-08-01

    Controlling the morphology of the sulfide inclusion is of vital importance in enhancing the properties of structural steel. Long strip-shaped sulfides in hot-rolled steel can spherize when, instead of the inclusion of pure single-phase MnS, the guest is a complex sulfide, such as an oxide-sulfide duplex and a solid-solution sulfide particle. In this study, the inclusions in a commercial rolled structural steel were investigated. Spherical and elongated oxide-sulfide duplex as well as single-phase (Mn,Ca)S solid solution inclusions were observed in the steel. A thermodynamic equilibrium between the oxide and sulfide inclusions was proposed to understand the oxide-sulfide duplex inclusion formation. Based on the equilibrium solidification principle, thermodynamic discussions on inclusion precipitation during the solidification process were performed for both general and resulfurized structural steel. The predicted results of the present study agreed well with the experimental ones.

  1. Synthesis and characterization of phosphates in molten systems Cs 2O-P 2O 5-CaO- MIII2O 3 ( MIII—Al, Fe, Cr)

    NASA Astrophysics Data System (ADS)

    Zatovsky, Igor V.; Strutynska, Nataliya Yu.; Baumer, Vyacheslav N.; Slobodyanik, Nikolay S.; Ogorodnyk, Ivan V.; Shishkin, Oleg V.

    2011-03-01

    The crystallization of complex phosphates from the melts of Cs 2O-P 2O 5-CaO- MIII2O 3 ( MIII—Al, Fe, Cr) systems have been investigated at fixed value Cs/P molar ratios equal to 0.7, 1.0 and 1.3 and Са/Р=0.2 and Ca/ МIII=1. The fields of crystallization of CsCaP 3O 9, β-Ca 2P 2O 7, Cs 2CaP 2O 7, Cs 3CaFe(P 2O 7) 2, Ca 9MIII(PO 4) 7 ( MIII—Fe, Cr), Cs 0.63Ca 9.63Fe 0.37(PO 4) 7 and CsCa 10(PO 4) 7 were determined. Obtained phosphates were investigated using powder X-ray diffraction and FTIR spectroscopy. Novel whitlockite-related phases CsCa 10(PO 4) 7 and Cs 0.63Ca 9.63Fe 0.37(PO 4) 7 have been characterized by single crystal X-ray diffraction: space group R3c, a=10.5536(5) and 10.5221(4) Å, с=37.2283(19) and 37.2405(17) Å, respectively.

  2. Aluminum resistance in wheat involves maintenance of leaf Ca(2+) and Mg(2+) content, decreased lipid peroxidation and Al accumulation, and low photosystem II excitation pressure.

    PubMed

    Moustaka, Julietta; Ouzounidou, Georgia; Bayçu, Gülriz; Moustakas, Michael

    2016-08-01

    The phytotoxic aluminum species (Al(3+)) is considered as the primary factor limiting crop productivity in over 40 % of world's arable land that is acidic. We evaluated the responses of two wheat cultivars (Triticum aestivum L.) with differential Al resistance, cv. Yecora E (Al-resistant) and cv. Dio (Al-sensitive), exposed to 0, 37, 74 and 148 μM Al for 14 days in hydroponic culture at pH 4.5. With increasing Al concentration, leaf Ca(2+) and Mg(2+) content decreased, as well as the effective quantum yield of photosystem II (PSII) photochemistry (Φ PSII ), while a gradual increase in leaf membrane lipid peroxidation, Al accumulation, photoinhibition (estimated as F v /F m ), and PSII excitation pressure (1 - q p ) occurred. However, the Al-resistant cultivar with lower Al accumulation, retained larger concentrations of Ca(2+) and Mg(2+) in the leaves and kept a larger fraction of the PSII reaction centres (RCs) in an open configuration, i.e. a higher ratio of oxidized to reduced quinone A (QA), than plants of the Al-sensitive cultivar. Four times higher Al concentration in the nutrient solution was required for Al-resistant plants (148 μM Al) than for Al-sensitive (37 μM Al), in order to establish the same closed RCs. Yet, the decline in photosynthetic efficiency in the cultivar Dio was not only due to closure of PSII RCs but also to a decrease in the quantum yield of the open RCs. We suggest that Al(3+) toxicity may be mediated by nutrient deficiency and oxidative stress, and that Al-resistance of the wheat cultivar Yecora E, may be due at least partially, from the decreased Al accumulation that resulted to decreased reactive oxygen species (ROS) formation. However, under equal internal Al accumulation (exposure Al concentration: Dio 74 μM, Yecora E 148 μM) that resulted to the same oxidative stress, the reduced PSII excitation pressure and the better PSII functioning of the Al-resistant cultivar was probably due to the larger concentrations of Ca

  3. Photocatalytic characteristics for the nanocrystalline TiO2 on the Ag-doped CaAl2O4:(Eu,Nd) phosphor

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Sik; Sung, Hyun-Je; Kim, Bum-Joon

    2015-04-01

    This study investigated the photocatalytic behavior of nanocrystalline TiO2 deposited on Ag-doped long-lasting phosphor (CaAl2O4:Eu2+,Nd3+). The CaAl2O4:Eu2+,Nd3+ phosphor powders were prepared via conventional sintering using CaCO3, Al2O3, Eu2O3, and Nd2O3 as raw materials according to the appropriate molar ratios. Silver nanoparticles were loaded on the phosphor by mixing with an aqueous Ag-dispersion solution. Nanocrystalline TiO2 was deposited on Ag-doped CaAl2O4:Eu2+,Nd3+ powders via low-pressure chemical vapor deposition (LPCVD). The TiO2 coated on the phosphor was actively photo-reactive under irradiation with visible light and showed much faster benzene degradation than pure TiO2, which is almost non-reactive. The coupling of TiO2 with phosphor may result in an energy band bending in the junction region, which then induces the TiO2 crystal at the interface to be photo-reactive under irradiation with visible light. In addition, the intermetallic compound of CaTiO3 that formed at the interface between TiO2 and the CaAl2O4:(Eu2+,Nd3+) phosphor results in the formation of oxygen vacancies and additional electrons that promote the photodecomposition of benzene gas. The addition of Ag nanoparticles enhanced the photocatalytic reactivity of the TiO2/CaAl2O4:Eu2+,Nd3+ phosphor. TiO2 on the Ag-doped phosphor presented a higher benzene gas decomposition rate than the TiO2 did on the phosphor without Ag-doping under both irradiation with ultraviolet and visible light.

  4. Molecular dynamics simulation of radiation damage in CaCd{sub 6} quasicrystal cubic approximant up to 10 keV

    SciTech Connect

    Chen, P. H.; Avchachov, K.; Nordlund, K.; Pussi, K.

    2013-06-21

    Due to the peculiar nature of the atomic order in quasicrystals, examining phase transitions in this class of materials is of particular interest. Energetic particle irradiation can provide a way to modify the structure locally in a quasicrystal. To examine irradiation-induced phase transitions in quasicrystals on the atomic scale, we have carried out molecular dynamics simulations of collision cascades in CaCd{sub 6} quasicrystal cubic approximant with energies up to 10 keV at 0 and 300 K. The results show that the threshold energies depend surprisingly strongly on the local coordination environments. The energy dependence of stable defect formation exhibits a power-law dependence on cascade energy, and surviving defects are dominated by Cd interstitials and vacancies. Only a modest effect of temperature is observed on defect survival, while irradiation temperature increases lead to a slight increase in the average size of both vacancy clusters and interstitial clusters.

  5. Laser deposited biocompatible Ca-P coatings on Ti-6Al-4V: microstructural evolution and thermal modeling.

    PubMed

    Nag, Soumya; Paital, Sameer R; Nandawana, Peeyush; Mahdak, Kristopher; Ho, Yee Hsien; Vora, Hitesh D; Banerjee, Rajarshi; Dahotre, Narendra B

    2013-01-01

    A high intensity continuous wave diode pumped ytterbium laser source was used to deposit Ca-P coatings on a Ti-6Al-4V biocompatible alloy in order to generate a physically textured surface, enhancing osseointegration. Scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and energy dispersive spectroscopy (EDS) studies were coupled with X-ray and micro diffraction work to determine the structure, composition, and phases present in various zones of a sample prepared across the coating/substrate interaction zone. Three-dimensional thermal modeling was also carried out to determine the cooling rate and maximum temperature experienced by different regions of the substrate. Combining these results provide us with valuable insights regarding the thermo-physical as well as chemical interactions that take place across the coating-substrate interface.

  6. Study of photoluminescence properties of CaAl2O4: Eu2+ prepared by combustion synthesis method

    NASA Astrophysics Data System (ADS)

    Hingwe, V. S.; Bajaj, N. S.; Omanwar, S. K.

    2016-05-01

    Eu2+ doped alkaline earth metals such as strontium aluminate, calcium aluminate and barium aluminate prepared by using modified combustion synthesis method at 600°c with Urea as fuel. Crystal structure is determined by using XRD and the sample confirmation by using the FTIR. The effect of the host material on the photoluminescence (PL) and phosphorescence properties were studied by using the Hitachi F-7000 spectrofluorimeter equipped with a 450W Xenon lamp, in the range 200-650 nm. The emission spectra of Eu2+ range from 450 to 500nm in the Blue to aqua region and the transition 4f7-4f6 5d1. The observed emission in CaAl2O4 is 440nm.

  7. Diode-pumped Kerr-lens mode-locked Yb:CaGdAlO4 laser with tunable wavelength

    NASA Astrophysics Data System (ADS)

    Gao, Ziye; Zhu, Jiangfeng; Wang, Junli; Wang, Zhaohua; Wei, Zhiyi; Xu, Xiaodong; Zheng, Lihe; Su, Liangbi; Xu, Jun

    2016-01-01

    We experimentally demonstrated a wavelength tunable Kerr-lens mode-locked femtosecond laser based on an Yb:CaGdAlO4 (Yb:CGA) crystal. The Kerr-lens mode-locked wavelength tuning range was from 1043.5 to 1076 nm, as broad as 32.5 nm, by slightly tilting the end mirror. Pulses as short as 60 fs were generated at the central wavelength of 1043.8 nm with an average output power of 66 mW. By using an output coupler with 1.5% transmittance, the Kerr-lens mode-locked average output power reached 127 mW with a pulse duration of 81 fs at a central wavelength of 1049.5 nm.

  8. Composition and mineralogy of refractory-metal-rich assemblages from a Ca,Al-rich inclusion in the Allende meteorite

    SciTech Connect

    Bischoff, A. Institut fuer Mineralogie, Muenster ); Palme, H. )

    1987-10-01

    The authors have separated four refractory metal-rich samples (10 {mu}g to 190 {mu}g) from a single Ca,Al-inclusion of the Allende meteorite. Chemical analyses were performed by INAA. From the analyzed samples polished sections were prepared. Mineral phases from six large Fremdlinge and the surrounding inclusion were analyzed by EDS. Three of the four separated samples have variable absolute but similar relative abundances of refractory metals. The pattern is controlled by volatility. The most refractory metals W, Os, and Re are enriched relative to the less refractory metals Ir, Mo, Ru, and Pt. This pattern can be reproduced by condensation calculations. A metal alloy in equilibrium with a gas of solar composition at a temperature of 1672 K, a pressure of 10{sup {minus}3} atm, and an H{sub 2}O/H{sub 2}-ratio of 5 {times} 10{sup {minus}3} would have the same abundance pattern. All six Fremdlinge have similar texture and mineralogy. They are composed of Ni-rich metal containing 2-9% Ir, surrounded by a fine-grained intergrowth of V-magnetite and FeS. The Ni-Fe metal poikilitically encloses tiny Os-particles, domains of a W- and Mo-rich solid solution (Ca(W,Mo)O{sub 4}) and V-magnetite. Based on chemical and textural information obtained in this study the formation of these aggregates in four steps is suggested: (1) condensation of a refractory metal alloys (W, Os, Re, Ir, Mo, Ru); (2) oxidation of the refractory metal alloy, allowing formation of Ca(W,Mo)O{sub 4}; (3) condensation of Ni-rich metal and V-magnetite at high oxygen fugacity (relative to the f{sub O{sub 2}} in a solar gas); (4) reaction of the existing assemblage with S to form FeS at lower temperatures.

  9. Thermal equation of state of CaFe 2O 4-type MgAl 2O 4

    NASA Astrophysics Data System (ADS)

    Sueda, Yuichiro; Irifune, Tetsuo; Sanehira, Takeshi; Yagi, Takehiko; Nishiyama, Norimasa; Kikegawa, Takumi; Funakoshi, Ken-ichi

    2009-05-01

    In situ X-ray diffraction measurements of CaFe 2O 4-type MgAl 2O 4 have been conducted at pressures up to 42 GPa and temperatures to 2400 K using Kawai-type multianvil apparatus with sintered diamond anvils. Additional measurements have also been conducted at pressures to 12 GPa using diamond anvil cell with helium as a pressure medium at room temperature, and at temperatures to 836 K at the ambient pressure using a high-temperature X-ray diffractometer. The analysis of room-temperature data yielded V0 = 240.1(2) Å 3, K0 = 205(6) GPa, and K0=4.1(3). A fit of the present data to high-temperature Birch-Murnaghan equation of state (EOS) yielded (∂ K0/∂ T) P = -0.030(2) GPa/K and α0 = a0 + b0T with values of a0 = 1.96(13) × 10 -5 K -1 and b0 = 1.64(24) × 10 -8 K -2. The present data set was also fitted to Mie-Grüneisen-Debye (MGD) EOS and we obtained γ0 = 1.73(7), q = 2.03(37), and θ0 = 1546(104) K. Density changes of MORB have been estimated using the newly obtained thermoelastic parameters, assuming that the Al-rich phase in this composition possesses the CaFe 2O 4-type structure under the lower mantle P, T conditions. The calculated densities along geotherms for the normal mantle and subducting cold slabs are both significantly higher than those of typical seismological models, confirming the conclusion of some recent results on MORB by laser-heated diamond anvil cell experiments.

  10. Novel ZnO:Al contacts to CdZnTe for X- and gamma-ray detectors.

    PubMed

    Roy, U N; Mundle, R M; Camarda, G S; Cui, Y; Gul, R; Hossain, A; Yang, G; Pradhan, A K; James, R B

    2016-01-01

    CdZnTe (CZT) has made a significant impact as a material for room-temperature nuclear-radiation detectors due to its potential impact in applications related to nonproliferation, homeland security, medical imaging, and gamma-ray telescopes. In all such applications, common metals, such as gold, platinum and indium, have been used as electrodes for fabricating the detectors. Because of the large mismatch in the thermal-expansion coefficient between the metal contacts and CZT, the contacts can undergo stress and mechanical degradation, which is the main cause for device instability over the long term. Here, we report for the first time on our use of Al-doped ZnO as the preferred electrode for such detectors. The material was selected because of its better contact properties compared to those of the metals commonly used today. Comparisons were conducted for the detector properties using different contacts, and improvements in the performances of ZnO:Al-coated detectors are described in this paper. These studies show that Al:ZnO contacts to CZT radiation detectors offer the potential of becoming a transformative replacement for the common metallic contacts due to the dramatic improvements in the performance of detectors and improved long-term stability. PMID:27216387

  11. Novel ZnO:Al contacts to CdZnTe for X- and gamma-ray detectors

    PubMed Central

    Roy, U. N.; Mundle, R. M.; Camarda, G. S.; Cui, Y.; Gul, R.; Hossain, A.; Yang, G.; Pradhan, A. K.; James, R. B.

    2016-01-01

    CdZnTe (CZT) has made a significant impact as a material for room-temperature nuclear-radiation detectors due to its potential impact in applications related to nonproliferation, homeland security, medical imaging, and gamma-ray telescopes. In all such applications, common metals, such as gold, platinum and indium, have been used as electrodes for fabricating the detectors. Because of the large mismatch in the thermal-expansion coefficient between the metal contacts and CZT, the contacts can undergo stress and mechanical degradation, which is the main cause for device instability over the long term. Here, we report for the first time on our use of Al-doped ZnO as the preferred electrode for such detectors. The material was selected because of its better contact properties compared to those of the metals commonly used today. Comparisons were conducted for the detector properties using different contacts, and improvements in the performances of ZnO:Al-coated detectors are described in this paper. These studies show that Al:ZnO contacts to CZT radiation detectors offer the potential of becoming a transformative replacement for the common metallic contacts due to the dramatic improvements in the performance of detectors and improved long-term stability. PMID:27216387

  12. Novel ZnO:Al contacts to CdZnTe for X- and gamma-ray detectors

    NASA Astrophysics Data System (ADS)

    Roy, U. N.; Mundle, R. M.; Camarda, G. S.; Cui, Y.; Gul, R.; Hossain, A.; Yang, G.; Pradhan, A. K.; James, R. B.

    2016-05-01

    CdZnTe (CZT) has made a significant impact as a material for room-temperature nuclear-radiation detectors due to its potential impact in applications related to nonproliferation, homeland security, medical imaging, and gamma-ray telescopes. In all such applications, common metals, such as gold, platinum and indium, have been used as electrodes for fabricating the detectors. Because of the large mismatch in the thermal-expansion coefficient between the metal contacts and CZT, the contacts can undergo stress and mechanical degradation, which is the main cause for device instability over the long term. Here, we report for the first time on our use of Al-doped ZnO as the preferred electrode for such detectors. The material was selected because of its better contact properties compared to those of the metals commonly used today. Comparisons were conducted for the detector properties using different contacts, and improvements in the performances of ZnO:Al-coated detectors are described in this paper. These studies show that Al:ZnO contacts to CZT radiation detectors offer the potential of becoming a transformative replacement for the common metallic contacts due to the dramatic improvements in the performance of detectors and improved long-term stability.

  13. Fluoride evaporation and crystallization behavior of CaF2-CaO-Al2O3-(TiO2) slag for electroslag remelting of Ti-containing steels

    NASA Astrophysics Data System (ADS)

    Shi, Cheng-bin; Cho, Jung-wook; Zheng, Ding-li; Li, Jing

    2016-06-01

    To elucidate the behavior of slag films in an electroslag remelting process, the fluoride evaporation and crystallization of CaF2-CaO-Al2O3-(TiO2) slags were studied using the single hot thermocouple technique. The crystallization mechanism of TiO2-bearing slag was identified based on kinetic analysis. The fluoride evaporation and incubation time of crystallization in TiO2-free slag are found to considerably decrease with decreasing isothermal temperature down to 1503 K. Fish-bone and flower-like CaO crystals precipitate in TiO2-free slag melt, which is accompanied by CaF2 evaporation from slag melt above 1503 K. Below 1503 K, only near-spherical CaF2 crystals form with an incubation time of less than 1 s, and the crystallization is completed within 1 s. The addition of 8.1wt% TiO2 largely prevents the fluoride evaporation from slag melt and promotes the slag crystallization. TiO2 addition leads to the precipitation of needle-like perovskite (CaTiO3) crystals instead of CaO crystals in the slag. The crystallization of perovskite (CaTiO3) occurs by bulk nucleation and diffusion-controlled one-dimensional growth.

  14. Temperature dependent electrical properties of Al/Cd0.8Zn0.2S/ITO Schottky diode

    NASA Astrophysics Data System (ADS)

    M, Parameshwari P.; V, Shrisha B.; Naik, K. Gopalakrishna

    2015-06-01

    In this work effect of temperature on the current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Al/Cd0.8Zn0.2S/ITO diode were studied. The series resistance, Schottky barrier height and ideality factor of the diode were obtained from the forward I-V characteristics at temperatures ranging193 K - 303 K. Activation energy of the diode was calculated from the reverse bias I-V characteristics. Room temperature C - V measurement was used to find the carrier concentration (NA) and built in voltage (Vb) of the diode. Schottky barrier height (ΦB) was also measured from C-V characteristics at room temperature.

  15. Characterization of polarization phenomenon in Al-Schottky CdTe detectors using a spectroscopic analysis method

    NASA Astrophysics Data System (ADS)

    Meuris, Aline; Limousin, Olivier; Blondel, Claire

    2011-10-01

    CdTe radiation detectors equipped with Schottky contacts are known to show spectral response degradation over time under biasing. Nevertheless, they can be used as high-resolution spectrometers for X-rays and gamma-rays with moderate cooling and high voltage. Spectroscopic long-term measurements have been performed with Al/CdTe/Pt pixel detectors of 0.5, 1 and 2 mm thicknesses and 241Am source from -13 to +16 °C to evaluate how long they can be operated. Experimental results are confronted to simulations using the charge accumulation model for electric field. Activation energy for collection efficiency stability and peak shift was measured at 1.0-1.2 eV although deep acceptor levels responsible for hole detrapping during polarization were evaluated by other methods at EV +0.6-0.8 eV. The difference is probably due to a thermal effect of pre-polarization before biasing the detector.

  16. Al-doped ZnO contact to CdZnTe for x- and gamma-ray detector applications

    NASA Astrophysics Data System (ADS)

    Roy, U. N.; Camarda, G. S.; Cui, Y.; Gul, R.; Hossain, A.; Yang, G.; Mundle, R. M.; Pradhan, A. K.; James, R. B.

    2016-06-01

    The poor adhesion of common metals to CdZnTe (CZT)/CdTe surfaces has been a long-standing challenge for radiation detector applications. In this present work, we explored the use of an alternative electrode, viz., Al-doped ZnO (AZO) as a replacement to common metallic contacts. ZnO offers several advantages over the latter, such as having a higher hardness, a close match of the coefficients of thermal expansion for CZT and ZnO, and better adhesion to the surface of CZT due to the contact layer being an oxide. The AZO/CZT contact was investigated via high spatial-resolution X-ray response mapping for a planar detector at the micron level. The durability of the device was investigated by acquiring I-V measurements over an 18-month period, and good long-term stability was observed. We have demonstrated that the AZO/CZT/AZO virtual-Frisch-grid device performs fairly well, with comparable or better characteristics than that for the same detector fabricated with gold contacts.

  17. Synthesis of MgO-CaO-Al2O3-SiO2 nanocomposite powder by polymeric complex method as a novel sintering additive of AlN ceramics

    NASA Astrophysics Data System (ADS)

    Lee, Hwa-Jun; Cho, Woo-Seok; Kim, Hyeong Jun; Pan, Wei; Shahid, Mohammad; Ryu, Sung-Soo

    2016-09-01

    A MgO-CaO-Al2O3-SiO2 (MCAS) nanocomposite powder with a particle size of 50 nm and a specific surface area of 40.6 m2/g was successfully synthesized via heat-treatment of polymeric precursors containing Mg, Ca, Al and Si in air at 700 °C for 5 h. It was characterized as a novel sintering additive for the densification AlN ceramics at a low temperature below 1600 °C. It was found that the nanosized MCAS powder was suitable for the densification of AlN ceramics. In particular, full densification could be achieved when only 1.0 wt% MCAS additive-doped AlN powder compact was sintered for 1 h at 1600 °C, and a thermal conductivity of 84 W/m·K was attained.

  18. The pressure-volume equation of state of a synthetic grossular Ca3Al2Si3O12

    NASA Astrophysics Data System (ADS)

    Milani, Sula; Boffa Ballaran, Tiziana; Nestola, Fabrizio

    2014-05-01

    In the framework of a wide research project focused on mineral inclusions in diamonds we have investigated the compressibility of a synthetic grossular garnet (Ca3Al2Si3O12) with the purpose of providing new constraints on the diamond geobarometry. In fact, not only garnets are among the important phases of the Earth upper mantle but at the same time are one of the main phases found as inclusion in diamonds. Garnets are a crucial marker in determining the origin source of diamonds, which can be eclogitic and/or peridotitic. In particular, peridotitic diamonds include garnets characterized by about 90-92% of pyrope-almandine with the grossular component reaching about 6-8%, whereas eclogitic diamonds have garnets with the grossular component increased up to about 20-22%. In order to obtain information about the depth of formation of the diamond-garnet pair, beyond the classical chemical method, we propose the so called "elastic method", which is based on the knowledge of precise and accurate thermoelastic parameters for both diamond and inclusion (e.g. Nestola et al. 2011 and references therein). We have determined the pressure - volume equation of state of a pure synthetic grossular garnet by single-crystal X-ray diffraction up to about 8 GPa. The resulting equation of state coefficients, together with those previously determined for pyrope and almandine end-members and their intermediate compositions (see Milani et al. 2013) will cover the compositional range of garnets found as inclusions in diamonds, allowing to construct a robust model to predict the elastic parameters for any garnet composition typical of eclogitic and/or peridotitic diamond. The research was funded by the ERC Starting Grant to FN (grant agreement n° 307322). References Milani S., Mazzucchelli M., Nestola F., Alvaro M., Angel R.J., Geiger C.A., Domeneghetti M.C. (2013) The P-T conditions of garnet inclusion formation in diamond: thermal expansion of synthetic end-member pyrope. EGU General

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

    PubMed Central

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

    2013-01-01

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

  20. Teaching the modes of Ca2+ transport between the plasma membrane and endoplasmic reticulum using a classic paper by Kwan et al.

    PubMed

    Liang, Willmann

    2009-09-01

    This teaching article uses the report by Kwan et al., "Effects of methacholine, thapsigargin, and La(3+) on plasmalemmal and intracellular Ca(2+) transport in lacrimal acinar cells," where the effects of Ca(2+)-mobilizing agents in regulating Ca(2+) fluxes were examined under various conditions. Upper-level undergraduate and new graduate students in physiology are the targe audience. Teaching and learning points are put forth in this article to illustrate 1) the characteristics of methacholine- and thapsigargin-induced Ca(2+) responses, 2) the different endoplasmic reticulum Ca(2+) stores accessible to methacholine and thapsigargin, 3) the inhibitory effects of La(3+) on Ca(2+) extrusion and Ca(2+) influx, and 4) the facilitatory role of La(3+) on endoplasmic reticulum Ca(2+) recycling. Each of the above concepts is first explained with references to the figures adapted from the original article. A list of student learning questions then follows, where the answers are found in the teaching notes for the instructors. It is the objective of this article to make both teaching and learning Ca(2+) regulation a rewarding experience for all. PMID:19745042

  1. Adsorption of Cd(II) by Mg-Al-CO3- and magnetic Fe3O4/Mg-Al-CO3-layered double hydroxides: Kinetic, isothermal, thermodynamic and mechanistic studies.

    PubMed

    Shan, Ran-ran; Yan, Liang-guo; Yang, Kun; Hao, Yuan-feng; Du, Bin

    2015-12-15

    Understanding the adsorption mechanisms of metal cations on the surfaces of solids is important for determining the fate of these metals in water and wastewater treatment. The adsorption kinetic, isothermal, thermodynamic and mechanistic properties of cadmium (Cd(II)) in an aqueous solution containing Mg-Al-CO3- and magnetic Fe3O4/Mg-Al-CO3-layered double hydroxide (LDH) were studied. The results demonstrated that the adsorption kinetic and isotherm data followed the pseudo-second-order model and the Langmuir equation, respectively. The adsorption process of Cd(II) was feasible, spontaneous and endothermic in nature. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were used to explain the adsorption mechanisms. The characteristic XRD peaks and FTIR bands of CdCO3 emerged in the LDH spectra after Cd(II) adsorption, which indicated that the adsorption of Cd(II) by LDHs occurred mainly via CdCO3 precipitation, surface adsorption and surface complexation. Furthermore, the magnetic Fe3O4/Mg-Al-CO3-LDH can be quickly and easily separated using a magnet before and after the adsorption process.

  2. Structural features of AgCaCdMg{sub 2}(PO{sub 4}){sub 3} and AgCd{sub 2}Mg{sub 2}(PO{sub 4}){sub 3}, two new compounds with the alluaudite-type structure, and their catalytic activity in butan-2-ol conversion

    SciTech Connect

    Kacimi, Mohammed; Ziyad, Mahfoud; Hatert, Frederic . E-mail: fhatert@ulg.ac.be

    2005-04-20

    AgCaCdMg{sub 2}(PO{sub 4}){sub 3} and AgCd{sub 2}Mg{sub 2}(PO{sub 4}){sub 3}, two new compounds with the alluaudite-type structure, were synthesized by a solid state reaction in air at 750 deg. C. The X-ray powder diffraction pattern of AgCaCdMg{sub 2}(PO{sub 4}){sub 3} indicates the presence of small amounts of (Ca, Mg){sub 3}(PO{sub 4}){sub 2} with the whitlockite structure, as impurity, whereas AgCd{sub 2}Mg{sub 2}(PO{sub 4}){sub 3} is constituted by pure alluaudite. The Rietveld refinements of the X-ray powder diffraction patterns indicate an ordered cationic distribution for AgCd{sub 2}Mg{sub 2}(PO{sub 4}){sub 3}, with Ag on A(2)', Cd on A(1) and M(1), and Mg on M(2), whereas a disordered distribution of Cd and Ca between the A(1) and M(1) sites is observed for AgCaCdMg{sub 2}(PO{sub 4}){sub 3}. The catalytic properties of these compounds has been measured in reaction of butan-2-ol dehydrogenation. In the absence of oxygen, both samples exhibit poor dehydrogenation activity. All samples displayed no dehydration activity. Introduction of oxygen into the feed changed totally the catalytic behavior of the catalysts. The production of methyl ethyl ketone increases with time on stream and the reaction temperature. AgCaCdMg{sub 2}(PO{sub 4}){sub 3} is more efficient than AgCd{sub 2}Mg{sub 2}(PO{sub 4}){sub 3}.

  3. ABiO2X (A = Cd, Ca, Sr, Ba, Pb; X = halogen) Sillen X1 Series: Polymorphism Versus Optical Properties.

    PubMed

    Olchowka, Jacob; Kabbour, Houria; Colmont, Marie; Adlung, Matthias; Wickleder, Claudia; Mentré, Olivier

    2016-08-01

    The Sillen X1 series of Bi(3+)A(2+)O2X (A = Cd, Ca, Sr, Ba, Pb; X = Cl, Br, I) compounds is composed of three main crystallographic types, namely, the tetragonal form (space group (S.G.) I4/mmm), the orthorhombic form (S.G. Cmcm), and the monoclinic form (S.G. P21/m). Because of Bi(3+)/A(2+) disorder the Bi(3+) based photoluminescence (PL) of the tetragonal polytypes is quenched at room temperature (RT). In the two other ordered forms, the Bi-O-Bi connectivity is different but limited, such that bluish/greenish emission occurs at RT in the monoclinic CdBiO2Cl and CaBiO2Cl and orthorhombic SrBiO2Cl and BaBiO2Cl phases. The crystal structure of BaBiO2Br was refined in the orthorhombic Cmcm space group and also shows RT emission. Focusing on the RT luminescent activity as a key parameter, the PL active compounds were investigated by means of density functional theory calculations and UV-visible reflectance spectroscopy. The influence of A and X ions on the excitation energy is discussed by analyzing the A-O-Bi and Bi-X bonding schemes and gives some insights for rational tuning of both the excitation and emission energies. PMID:27414069

  4. Spin Hamiltonian parameters and local structures for Co 2+ ions in calcite-type trigonal carbonates MCO 3 (M=Co, Cd and Ca)

    NASA Astrophysics Data System (ADS)

    Wen-Chen, Zheng; Shao-Yi, Wu; Hui-Ning, Dong; Sheng, Tang

    2004-01-01

    From the perturbation formulas based on the cluster approach for 3d 7 ion in trigonal octahedral sites of crystals, the spin Hamiltonian parameters ( g factors g , g⊥ and hyperfine structure constants A , A⊥) for Co 2+ in calcite-type MCO 3 (M=Co, Cd, Ca) crystals are calculated. In the calculations, for CoCO 3 crystal, the structural data of pure crystal are used, whereas for the Co 2+-doped CdCO 3 and CaCO 3 crystals, the local structural data caused by the impurity-induced local lattice relaxation are considered. The calculated results show good agreement with the observed values obtained from electron paramagnetic and antiferromagnetic resonance experiments. The difficulty shown in the previous paper related to the g⊥ value of CoCO 3 obtained from the change of the g factor as a function of the crystallographic data (i.e., the unit cell parameters) a0 and α0 of pure MCO 3 crystals is removed.

  5. Determination of Ca, Mg, Na, Cd, Cu, Fe, K, Li and Zn in acid mine and reference water samples by inductively coupled plasma atomic fluorescence spectrometry

    USGS Publications Warehouse

    Sanzolone, R.F.; Meier, A.L.

    1986-01-01

    An inductively coupled plasma atomic fluorescence spectrometric (ICP-AFS) method was used for the determination of nine elements in natural water. Reference and acid mine water samples were analysed by this method to demonstrate its usefulness for hydrogeochemical exploration. The elements were determined in two groups based on the compatibility of operating conditions and consideration of element abundance levels in natural water. Ca, Mg and Na were determined as a group using one set of instrumental conditions and a 1 + 99 dilution of the sample, and Cd, Cu, Fe, K, Li and Zn were determined using another set of conditions and the undiluted sample. The detection limits for the elements are as follows: Ca, 1.4; Mg, 1.7; Na, 2.0; Cd, 1.8; Cu, 6.2; Fe, 15.8; K, 3.5; Li, 0.3; and Zn, 1.2 ng m1-1. Each element has a linear range spanning about four orders of magnitude. The method has good precision and accuracy, as shown by statistics on replicate analyses and by the agreement between values obtained and those recommended for the reference water samples, and also those obtained by atomic absorption spectrometry for the acid mine water samples.

  6. Crystal growth and magnetic properties of Ln-Mn-Al (Ln=Gd, Yb) compounds of the CaCr{sub 2}Al{sub 10} and ThMn{sub 12} structure types

    SciTech Connect

    Fulfer, Bradford W.; Haldolaarachchige, Neel; Young, David P.; Chan, Julia Y.

    2012-10-15

    We report the growth and characterization of LnMn{sub 2+x}Al{sub 10-x} (Ln=Gd, Yb) crystals adopting the CaCr{sub 2}Al{sub 10} and ThMn{sub 12} structure types. Single crystals of LnMn{sub 2+x}Al{sub 10-x} were synthesized via the self-flux method and characterized with single crystal X-ray diffraction. We compare LnMn{sub 2+x}Al{sub 10-x} compounds adopting the CaCr{sub 2}Al{sub 10} and ThMn{sub 12} structure types, and outline synthesis methods to obtain each polymorph. Magnetic susceptibility measurements show paramagnetic behavior down to 3 K for both CaCr{sub 2}Al{sub 10}- and ThMn{sub 12}-type compounds, with observed magnetic moments of 1.3{mu}{sub B} for compounds adopting the CaCr{sub 2}Al{sub 10} structure type to 4.2{mu}{sub B} for those adopting the ThMn{sub 12} structure type. Compounds of both structure type exhibit metallic resistivity, with upturns at low temperature attributed to Kondo scattering. - Graphical abstract: We report the growth and characterization of LnMn{sub 2+x}Al{sub 10-x} (Ln=Gd, Yb) crystals adopting the CaCr{sub 2}Al{sub 10} and ThMn{sub 12} structure types. Single crystals of LnMn{sub 2+x}Al{sub 10-x} were synthesized via the self-flux method and characterized with single crystal X-ray diffraction. We compare LnMn{sub 2+x}Al{sub 10-x} compounds adopting the CaCr{sub 2}Al{sub 10} and ThMn{sub 12} structure types, and outline synthesis methods to obtain each polymorph. Magnetic susceptibility measurements show paramagnetic behavior down to 3 K for both CaCr{sub 2}Al{sub 10}- and ThMn{sub 12}-type compounds, with observed magnetic moments of 1.3{mu}{sub B} for compounds adopting the CaCr{sub 2}Al{sub 10} structure type to 4.2{mu}{sub B} for those adopting the ThMn{sub 12} structure type. Compounds of both structure type exhibit metallic resistivity, with upturns at low temperature attributed to Kondo scattering. Highlights: Black-Right-Pointing-Pointer We have grown Ln (Mn,Al){sub 12} (Ln=Gd, Yb) single crystals of the ThMn{sub 12

  7. How do mineral coatings affect dissolution rates? An experimental study of coupled CaCO 3 dissolution—CdCO 3 precipitation

    NASA Astrophysics Data System (ADS)

    Cubillas, Pablo; Köhler, Stephan; Prieto, Manuel; Causserand, Carole; Oelkers, Eric H.

    2005-12-01

    Coupled CaCO 3 dissolution-otavite (CdCO 3) precipitation experiments have been performed to 1) quantify the effect of mineral coatings on dissolution rates, and 2) to explore the possible application of this coupled process to the remediation of polluted waters. All experiments were performed at 25°C in mixed-flow reactors. Various CaCO 3 solids were used in the experiments including calcite, aragonite, and ground clam, mussel, and cockle shells. Precipitation was induced by the presence of Cd(NO 3) 2 in the inlet solution, which combined with aqueous carbonate liberated by CaCO 3 dissolution to supersaturate otavite. The precipitation of an otavite layer of less than 0.01 μm in thickness on calcite surfaces decreases its dissolution rate by close to two orders of magnitude. This decrease in calcite dissolution rates lowers aqueous carbonate concentrations in the reactor such that the mixed-flow reactor experiments attain a steady-state where the reactive fluid is approximately in equilibrium with otavite, arresting its precipitation. In contrast, otavite coatings are far less efficient in lowering aragonite, and ground clam, mussel, and cockle shell dissolution rates, which are comprised primarily of aragonite. A steady-state is only attained after the precipitation of an otavite layer of 3-10 μm thick; the steady state CaCO 3 dissolution rate is 1-2 orders of magnitude lower than that in the absence of otavite coatings. The difference in behavior is interpreted to stem from the relative crystallographic structures of the dissolving and precipitating minerals. As otavite is isostructural with respect to calcite, it precipitates by epitaxial growth directly on the calcite, efficiently slowing dissolution. In contrast, otavite's structure is appreciably different from that of aragonite. Thus, it will precipitate by random three dimensional heterogeneous nucleation, leaving some pore space at the otavite-aragonite interface. This pore space allows aragonite

  8. Photoluminescence of CaAlSiN3:Eu2+-based fine red-emitting phosphors synthesized by carbothermal reduction and nitridation method

    NASA Astrophysics Data System (ADS)

    Li, Shuxing; Peng, Xia; Liu, Xuejian; Huang, Zhengren

    2014-12-01

    In this research, we have presented the synthesis and characterization of the various Ca1-xEuxAl0.76Si1.18N3 (x = 0.01 ∼ 0.1) red-emitting phosphors, which were successfully prepared by carbothermal reduction and nitridation (CTRN) method without the strict needs of high pressure. Here, raw materials were CaCO3, AlN, Si3N4, Eu2O3, and C. In particular, C was considered as efficient and robust reducing agent. The influences of reaction temperature, holding time, C content, and Eu2+ concentration were investigated in the crystal phase compositions and photoluminescence properties of the as-prepared phosphors. Importantly, CaAlSiN3:Eu2+-based red phosphors with interesting properties were obtained with reaction temperature at 1600 °C for 4 h by atmospheric N2-10%H2 pressure, and the C/O ratio of 1.5:1, respectively. The emission peak positions of as-prepared phosphors were red-shifted from 607 nm to 654 nm with Eu2+ concentration from 1 mol% to 10 mol%. Meanwhile the highest luminescence intensity was achieved with 2 mol% of Eu2+ concentration, which showed high external quantum efficiency up to 71%. Combining the phosphor blend of green-emitting β-sialon:Eu2+, yellow-emitting Ca-α-sialon:Eu2+, and red-emitting Ca0.98Eu0.02Al0.76Si1.18N3 with a blue LED (light emitting diodes), warm white LED can be generated, yielding the color rendering index (Ra) of 93 at correlated color temperature (CCT) of 3295 K. These results indicate that CaAlSiN3:Eu2+-based red-emitting phosphors prepared by facile CTRN are highly promising candidates for warm white LEDs.

  9. An ab initio study of the structural, elastic, electronic and optical properties of the newly synthesized nitridoaluminate LiCaAlN2

    NASA Astrophysics Data System (ADS)

    Haddadi, K.; Bouhemadou, A.; Bin-Omran, S.; Maabed, S.; Khenata, R.

    2015-01-01

    The structural parameters, elastic constants, electronic structure and optical properties of the recently reported monoclinic quaternary nitridoaluminate LiCaAlN2 are investigated in detail using the ab initio plane-wave pseudopotential method within the generalized gradient approximation. The calculated equilibrium structural parameters are in excellent agreement with the experimental data, which validate the reliability of the applied theoretical method. The chemical and structural stabilities of LiCaAlN2 are confirmed by calculating the cohesion energy and enthalpy of formation. Chemical band stiffness is calculated to explain the pressure dependence of the lattice parameters. Through the band structure calculation, LiCaAlN2 is predicted to be an indirect band gap of 2.725 eV. The charge-carrier effective masses are estimated from the band structure dispersions. The frequency-dependent dielectric function, absorption coefficient, refractive index, extinction coefficient, reflectivity coefficient and electron energy loss function spectra are calculated for polarized incident light in a wide energy range. Optical spectra exhibit a noticeable anisotropy. Single-crystal and polycrystalline elastic constants and related properties, including isotropic sound velocities and Debye temperatures, are numerically estimated. The calculated elastic constants and elastic compliances are used to analyse and visualize the elastic anisotropy of LiCaAlN2. The calculated elastic constants demonstrate the mechanical stability and brittle behaviour of the considered material.

  10. The elastic and thermoelectric properties of the Zintl compound Ca{sub 5}Al{sub 2}Sb{sub 6} under high pressure

    SciTech Connect

    Yang, Gui; Cui, Haitao; Ma, Dongwei; He, Chaozheng

    2014-12-14

    The elastic and thermoelectric properties of Ca{sub 5}Al{sub 2}Sb{sub 6} under pressure are studied using ab initio calculation and semiclassical Boltzmann theory. The calculated elastic constants and minimum thermal conductivity indicate that Ca{sub 5}Al{sub 2}Sb{sub 6} exhibits an anisotropic structure and high thermoelectric performance. The size of the band gap shows a nonlinear change with increasing pressure. Based on the electronic structure, the calculated thermoelectric parameters show that the Seebeck coefficient has no obvious change under pressure, whereas the electrical conductivity improves with increasing pressure. Therefore, the power factor increases at an appropriate pressure of P = 2.6 GPa. P-type doping of Ca{sub 5}Al{sub 2}Sb{sub 6} may achieve better thermoelectric performance than n-type doping, in agreement with experiment. The anisotropic thermoelectric properties of Ca{sub 5}Al{sub 2}Sb{sub 6} indicate that the thermoelectric performance along the z-direction is superior to other directions. This is attributed to the combination of the large dispersion and high band degeneracy along the Γ-Z direction in the band structure.

  11. Optimum Composition of CaO-SiO2-Al2O3-MgO Slag for Spring Steel Deoxidized by Si and Mn in Production

    NASA Astrophysics Data System (ADS)

    Yang, Hulin; Ye, Jiansong; Wu, Xiaoliang; Peng, Yongsheng; Fang, Yi; Zhao, Xinbing

    2016-04-01

    The relations between plasticity of inclusions and contents of oxygen, aluminum, and sulfur in molten steel were overall discussed by thermodynamics and FactSage software. Then, the optimum compositions of slag were obtained and the activities of components of refining slag system were analyzed. Finally, experiments were carried out based on the results of calculation. According to the relations, it could achieve better effect to improve basicity R ( R = CaO/SiO2 by mass pct) and C/ A ( C/ A = CaO/Al2O3 by mass pct) in the low melting temperature [≤1673 K (≤1400 °C)] region of refining slag as far as possible. For the CaO-SiO2-Al2O3-MgO slag, the optimum compositions are MgO: 5-9 pct, CaO: 47.4-50.2 pct, SiO2: 41.9-45.6 pct and Al2O3: ≤2.79 pct, respectively, in which the basicity is at the range of 1.0 to 1.19 and C/ A is above 9.0. It is proved by experiments that the plasticity of inclusions and the contents of [O], [Al], and [S] can be controlled effectively by the optimum composition of refining slag, and the high cleanness is achieved in spring wire rods.

  12. Blue, yellow and orange color emitting rare earth doped BaCa2Al8O15 phosphors prepared by combustion method

    NASA Astrophysics Data System (ADS)

    Yerpude, A. N.; Dhoble, S. J.; Reddy, B. Sudhakar

    2014-12-01

    Eu2+, Dy3+, Sm3+ activated BaCa2Al8O15 phosphors were prepared by the combustion method. The phosphor powders were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and photoluminescence (PL) spectrophotometer. Photoluminescence spectra of BaCa2Al8O15:Eu2+ phosphors show emission wavelength at 435 nm that corresponds to 4f65d1→4f7 transition of Eu2+ ion by keeping excitation wavelength extending broad-band from 270 to 400 nm centered at 334 nm. The Dy3+ doped BaCa2Al8O15 phosphors shows blue emission (485 nm) and yellow emission (566 nm) under the excitation of 347 nm, corresponding to the 4F9/2→6H15/2 transition and 4F9/2→6H13/2 transition of Dy3+ ions, respectively. The Sm3+ doped BaCa2Al8O15 phosphors have shown strong orange emission at 604 nm corresponding to the 4G5/2→6H7/2 transition of Sm3+ with intense excitation wavelength at 406 nm. Scanning electron microscopy has been used for exploring the size and morphological properties of the prepared phosphors. The obtained results show that the phosphors have potential application in the field of solid state lighting.

  13. Site-sensitive energy transfer modes in Ca3Al2O6: Ce(3+)/Tb(3+)/Mn(2+) phosphors.

    PubMed

    Zhang, Jilin; He, Yani; Qiu, Zhongxian; Zhang, Weilu; Zhou, Wenli; Yu, Liping; Lian, Shixun

    2014-12-28

    Ce(3+)/Eu(2+), Tb(3+) and Mn(2+) co-doping in single-phase hosts is a common strategy to achieve white-light phosphors via energy transfer, which provides a high color rendering index (CRI) value and good color stability. However, not all hosts are suitable for white-light phosphors due to inefficient energy transfer. In this study, the site-sensitive energy transfer from different crystallographic sites of Ce(3+) to Tb(3+)/Mn(2+) in Ca3Al2O6 has been investigated in detail. The energy transfer from purplish-blue Ce(3+) to Tb(3+) is an electric dipole-dipole mode, and the calculated critical distance (Rc) suggests the existence of purplish-blue Ce(3+)-Tb(3+) clusters. No energy transfer is observed from purplish-blue Ce(3+) to Mn(2+). In co-doped phosphors based on greenish-blue Ce(3+), however, the radiative mode dominates the energy transfer from Ce(3+) to Tb(3+), and an electric dipole-quadrupole interaction is responsible for the energy transfer from Ce(3+) to Mn(2+). A detailed discussion on the site-sensitive energy transfer modes might provide a new aspect to discuss and understand the possibilities and mechanisms of energy transfer, according to certain crystallographic sites in a complex host with different cation sites, as well as provide a possible approach in searching for single-phase white-light-emitting phosphors.

  14. Optimizing the Dopant and Carrier Concentration of Ca5Al2Sb6 for High Thermoelectric Efficiency

    PubMed Central

    Yan, Yuli; Zhang, Guangbiao; Wang, Chao; Peng, Chengxiao; Zhang, Peihong; Wang, Yuanxu; Ren, Wei

    2016-01-01

    The effects of doping on the transport properties of Ca5Al2Sb6 are investigated using first-principles electronic structure methods and Boltzmann transport theory. The calculated results show that a maximum ZT value of 1.45 is achieved with an optimum carrier concentration at 1000 K. However, experimental studies have shown that the maximum ZT value is no more than 1 at 1000 K. By comparing the calculated Seebeck coefficient with experimental values, we find that the low dopant solubility in this material is not conductive to achieve the optimum carrier concentration, leading a smaller experimental value of the maximum ZT. Interestingly, the calculated dopant formation energies suggest that optimum carrier concentrations can be achieved when the dopants and Sb atoms have similar electronic configurations. Therefore, it might be possible to achieve a maximum ZT value of 1.45 at 1000 K with suitable dopants. These results provide a valuable theoretical guidance for the synthesis of high-performance bulk thermoelectric materials through dopants optimization. PMID:27406178

  15. Optimizing the Dopant and Carrier Concentration of Ca5Al2Sb6 for High Thermoelectric Efficiency.

    PubMed

    Yan, Yuli; Zhang, Guangbiao; Wang, Chao; Peng, Chengxiao; Zhang, Peihong; Wang, Yuanxu; Ren, Wei

    2016-01-01

    The effects of doping on the transport properties of Ca5Al2Sb6 are investigated using first-principles electronic structure methods and Boltzmann transport theory. The calculated results show that a maximum ZT value of 1.45 is achieved with an optimum carrier concentration at 1000 K. However, experimental studies have shown that the maximum ZT value is no more than 1 at 1000 K. By comparing the calculated Seebeck coefficient with experimental values, we find that the low dopant solubility in this material is not conductive to achieve the optimum carrier concentration, leading a smaller experimental value of the maximum ZT. Interestingly, the calculated dopant formation energies suggest that optimum carrier concentrations can be achieved when the dopants and Sb atoms have similar electronic configurations. Therefore, it might be possible to achieve a maximum ZT value of 1.45 at 1000 K with suitable dopants. These results provide a valuable theoretical guidance for the synthesis of high-performance bulk thermoelectric materials through dopants optimization. PMID:27406178

  16. On the trapping of SOx on CaO-Al2O3-based novel high capacity sorbents.

    PubMed

    Dathe, Hendrik; Jentys, Andreas; Haider, Peter; Schreier, Ellen; Fricke, Rolf; Lercher, Johannes A

    2006-04-01

    Calcium-aluminum mixed oxide based materials doped with Na and Mn were explored as sulfur trapping materials. The materials showed a three times higher total storage capacity and a higher time on stream with complete SO2 removal compared to a second generation SOx trapping material which was mesoporous with calcium mainly present in oxidic form. Combining in situ XANES at the S K-edge and IR spectroscopy the key properties of the storage materials and the affiliated storage processes were identified. CaO-Al2O3 acts as the primary support and storage component, while Na+ cations adjust the base strength and enhances the storage capacity. Manganese cations provide the appropriate oxidation capacity in absence and presence of up to 10% water. The transport into the bulk phase, which is markedly influenced by a layer of sorbed water, is the rate-limiting step in presence of Mn cations. In the absence of manganese cations the oxidation step appears controlling the rate. The overall reaction network, identified by in situ IR spectroscopy and the 2D Correlation Analysis, is similar on all materials.

  17. Optimizing the Dopant and Carrier Concentration of Ca5Al2Sb6 for High Thermoelectric Efficiency

    NASA Astrophysics Data System (ADS)

    Yan, Yuli; Zhang, Guangbiao; Wang, Chao; Peng, Chengxiao; Zhang, Peihong; Wang, Yuanxu; Ren, Wei

    2016-07-01

    The effects of doping on the transport properties of Ca5Al2Sb6 are investigated using first-principles electronic structure methods and Boltzmann transport theory. The calculated results show that a maximum ZT value of 1.45 is achieved with an optimum carrier concentration at 1000 K. However, experimental studies have shown that the maximum ZT value is no more than 1 at 1000 K. By comparing the calculated Seebeck coefficient with experimental values, we find that the low dopant solubility in this material is not conductive to achieve the optimum carrier concentration, leading a smaller experimental value of the maximum ZT. Interestingly, the calculated dopant formation energies suggest that optimum carrier concentrations can be achieved when the dopants and Sb atoms have similar electronic configurations. Therefore, it might be possible to achieve a maximum ZT value of 1.45 at 1000 K with suitable dopants. These results provide a valuable theoretical guidance for the synthesis of high-performance bulk thermoelectric materials through dopants optimization.

  18. Effect of Agitation on Crystallization Behavior of CaO-Al2O3-SiO2-Na2O-CaF2 Mold Fluxes with Varying Basicity

    NASA Astrophysics Data System (ADS)

    Li, Jiangling; Shu, Qifeng; Chou, Kuochih

    2015-08-01

    The effect of agitation on crystallization behaviors of CaO-Al2O3-SiO2-Na2O-CaF2 mold fluxes with basicity of 1.1 and 1.2 was investigated. It was found that crystallization temperatures of agitated samples were higher than those of static samples. The morphology of cuspidine shifted from dendrites to facet crystals with the decrease of temperature. The agitation was conducive to the formation of small dendritic cuspidine and could lead to crystals with smaller size. Crystalline fraction could be significantly enhanced by agitation at the initial stage of crystallization.

  19. Effects of CaO/SiO2 Ratio and Na2O Content on Melting Properties and Viscosity of SiO2-CaO-Al2O3-B2O3-Na2O Mold Fluxes

    NASA Astrophysics Data System (ADS)

    Wang, Lin; Zhang, Chen; Cai, Dexiang; Zhang, Jianqiang; Sasaki, Yasushi; Ostrovski, Oleg

    2016-09-01

    This paper investigated the effects of CaO/SiO2 ratio (0.8 to 1.5) and Na2O concentration (6 to 9 wt pct) on melting properties and viscosity of SiO2-CaO-Al2O3-B2O3-Na2O mold fluxes with a fixed B2O3 content. Melting properties of fluxes (softening temperature T s, hemispherical temperature T h, and fluidity temperature T f) were determined by the hot-stage microscopy method. Viscosity was measured using rotating cylindrical viscometer, and structure of quenched fluxes was studied using Raman spectroscopy. Equilibrium phases in the SiO2-CaO-Al2O3-B2O3-Na2O system were calculated using FactSage. It was found that T h decreased with increasing CaO/SiO2 ratio from 0.8 to 1.0 and increased with a further increase in the CaO/SiO2 ratio to 1.5. The effect of Na2O content in the range of 6 to 9 wt pct on T h of the flux with a fixed CaO/SiO2 ratio at 1.3 was marginal. Increasing CaO/SiO2 ratio and Na2O content increased the break temperature and reduced the value of viscosity at 1673 K (1400 °C). Viscosity of liquid fluxes was discussed in the relationship with the flux structure. Melting properties and viscosity of boracic fluxes were compared with those of industrial fluorine-containing mold fluxes.

  20. Enhanced Emission from Li2CaSiO4:Dy3+ Phosphors by Doping with Al3+ and B3+

    NASA Astrophysics Data System (ADS)

    Erdoğmuş, E.

    2016-05-01

    Pure Li2CaSiO4, Li2CaSiO4:Dy3+ and Al3+, B3+ co-doped materials were prepared by a solid-state reaction in air at 900°C for 6 h and characterized by using powder XRD. The luminescence properties of the synthesized phosphors were measured at room temperature with a spectrofluorometer. Li2CaSiO4:Dy3+ emits at 484, 575, and 660 nm upon 352 nm excitation. The emission spectrum intensity of Dy3+ increased from 0.01 to 0.06 mol.%, and beyond 0.06 mol.%, concentration quenching was observed. Also, in this study, the effects of boric acid and aluminum oxide concentration on the photoluminescence properties of Dy3+ doped phosphors were investigated. The results showed that boric acid and aluminum oxide were effective in improving the photoluminescence intensity of Li2CaSiO4:Dy3+ compounds.

  1. Microstructure and wear behavior of γ/Al 4C 3/TiC/CaF 2 composite coating on γ-TiAl intermetallic alloy prepared by Nd:YAG laser cladding

    NASA Astrophysics Data System (ADS)

    Liu, Xiu-Bo; Shi, Shi-Hong; Guo, Jian; Fu, Ge-Yan; Wang, Ming-Di

    2009-03-01

    As a further step in obtaining high performance elevated temperature self-lubrication anti-wear composite coatings on TiAl alloy, a novel Ni-P electroless plating method was adopted to encapsulate the as-received CaF 2 in the preparation of precursor NiCr-Cr 3C 2-CaF 2 mixed powders with an aim to decrease its mass loss and increase its compatibility with the metal matrix during a Nd:YAG laser cladding. The microstructure of the coating was examined using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) and the friction and wear behavior of the composite coatings sliding against the hardened 0.45% C steel ring was evaluated using a block-on-ring wear tester at room temperature. It was found that the coating had a unique microstructure consisting of primary dendrites TiC and block Al 4C 3 carbides reinforcement as well as fine isolated spherical CaF 2 solid lubrication particles uniformly dispersed in the NiCrAlTi ( γ) matrix. The good friction-reducing and anti-wear abilities of the laser clad composite coating was suggested to the Ni-P electroless plating and the attendant reduction of mass loss of CaF 2 and the increasing of it's wettability with the NiCrAlTi ( γ) matrix during the laser cladding process.

  2. Effect of partial nitridation on the structure and luminescence properties of melilite-type Ca2Al2SiO7:Eu2+ phosphor

    NASA Astrophysics Data System (ADS)

    Luo, Yi; Xia, Zhiguo

    2014-09-01

    Ca1.97Al2-xSi1+xO7-xNx:0.03Eu2+ (x = 0-0.4) phosphors have been prepared by using the high temperature solid-state reaction. The effect of phase structures, photoluminescence (PL) properties and the thermal stabilities have been investigated based on the substitution of Al-O bond in Ca2Al2SiO7:Eu2+ phosphor with Si-N bond. The XRD Rietveld refinement and 29Si NMR analysis results verify the introduction of partial Si-N bonds. It is found that the PL spectra shift to the blue region abnormally from 530 to 515 nm, and the possible mechanism has been proposed. The activation energy becomes large along with the nitridation process, which coincides with the explanation of configuration coordinate diagram.

  3. Effects of Ca and H2O2 added to RPMI on the fretting corrosion of Ti6Al4V.

    PubMed

    Montague, A; Merritt, K; Brown, S; Payer, J

    1996-12-01

    Titanium and its alloys have demonstrated considerable success in various surgical procedures including orthopedic, dental, and cardiovascular surgery. However, particulate debris from corrosion and wear is present in a considerable quantity in tissue local to the implant. This study evaluated the effect of Ca, since it is present in both serum and bone, and H2O2, since it is produced through local inflammation, on the amount of titanium release. Four sets of Ti6Al4V plates and Ti6Al4V screws were used. Each set was designated to one of four solutions: RPMI (cell culture growth media), RPMI with CaCl2, RPMI with CaCO3, and RPMI with H2O2. A fretter was used to cause corrosion by creating micromotion between two screws and a two-hole plate of Ti6Al4V. After fretting for 72 h, weight loss of the plate and screws and the amount of Ti and vanadium (V) in solution was used to assess the amount of fretting corrosion which had occurred. Results of weight loss and Ti in solution indicated that the presence of H2O2 increased the amount of particulate debris produced in RPMI as compared with RPMI alone. The addition of CaCl2 to RPMI also increased both weight loss and Ti in solution compared with RPMI alone. The addition of CaCO2, however, did not give values significantly different from RPMI alone. Comparison of weight loss and Ti in solution indicated that the increase in fretting corrosion was not different between RPMI with CaCl2 and RPMI with H2O2. The particulate wear debris from the four solutions was black in color and the size of the particulate produced was compared using a Coulter Multisizer. The results indicated that particles produced in the four solutions were not different, with mean values between 1.324 and 1.100 microns, and they were similar in size to the particulate found in tissues surrounding failed total hip replacements. In order to better understand the role of Ca in the fretting corrosion of Ti6Al4V, energy dispersive x-ray analysis (EDXA) using

  4. Probing structure-induced optical behavior in a new class of self-activated luminescent 0D/1D CaWO₄ metal oxide – CdSe nanocrystal composite heterostructures

    DOE PAGES

    Han, Jinkyu; McBean, Coray; Wang, Lei; Hoy, Jessica; Jaye, Cherno; Liu, Haiqing; Li, Zhuo-Qun; Sfeir, Matthew Y.; Fischer, Daniel A.; Taylor, Gordon T.; et al

    2015-01-30

    In this report, we synthesize and characterize the structural and optical properties of novel heterostructures composed of (i) semiconducting nanocrystalline CdSe quantum dot (QDs) coupled with (ii) both one and zero-dimensional (1D and 0D) motifs of self-activated luminescence CaWO₄ metal oxides. Specifically, ~4 nm CdSe QDs have been anchored onto (i) high-aspect ratio 1D nanowires, measuring ~230 nm in diameter and ~3 μm in length, as well as onto (ii) crystalline 0D nanoparticles (possessing an average diameter of ~ 80 nm) of CaWO₄ through the mediation of 3-mercaptopropionic acid (MPA) as a connecting linker. Composite formation was confirmed by complementarymore » electron microscopy and spectroscopy (i.e. IR and Raman) data. In terms of luminescent properties, our results show that our 1D and 0D heterostructures evince photoluminescence (PL) quenching and shortened PL lifetimes of CaWO₄ as compared with unbound CaWO₄. We propose that a photo-induced electron transfer process occurs from CaWO₄ to CdSe QDs, a scenario which has been confirmed by NEXAFS measurements and which highlights a decrease in the number of unoccupied orbitals in the conduction bands of CdSe QDs. By contrast, the PL signature and lifetimes of MPA-capped CdSe QDs within these heterostructures do not exhibit noticeable changes as compared with unbound MPA-capped CdSe QDs. The striking difference in optical behavior between CaWO₄ nanostructures and CdSe QDs within our heterostructures can be correlated with the relative positions of their conduction and valence energy band levels. In addition, the PL quenching behaviors for CaWO₄ within the heterostructure configuration were examined by systematically varying (i) the quantities and coverage densities of CdSe QDs as well as (ii) the intrinsic morphology (and by extension, the inherent crystallite size) of CaWO₄ itself.« less

  5. Optically stimulated luminescence (OSL) response of Al2O3:C, BaFCl:Eu and K2Ca2(SO4)3:Eu phosphors.

    PubMed

    Kumar, Pratik; Bahl, Shaila; Sahare, P D; Kumar, Surender; Singh, Manveer

    2015-12-01

    This paper investigates the optically stimulated luminescence (OSL) response of BaFCl:Eu and K2Ca2(SO4)3:Eu phosphors for different doses and bleaching durations. The results have also been compared with the commercially available Landauer Al2O3:C (Luxel®) dosemeter. Nanocrystalline K2Ca2(SO4)3:Eu is known to be a sensitive thermoluminescent phosphor, but its OSL response is hardly reported. At first, pellets of nanocrystalline K2Ca2(SO4)3:Eu powder were prepared by adding Teflon as a binder. Their OSL signal was compared with that of the material in pure form, i.e. without adding the binder (in 100:1 ratio). It was observed that adding the binder does not appreciably affect the OSL intensity. On comparison with the commercially available Al2O3:C from Landauer, it was found that K2Ca2(SO4)3:Eu is around 15 times less sensitive than Al2O3:C. 'Homemade' BaFCl:Eu phosphor has also been studied. The intensity of BaFCl:Eu was ∼20 times more than the standard Al2O3:C dosemeter and ∼200 times more sensitive than K2Ca2(SO4)3:Eu in the dose range of 13-200 cGy. OSL dosemeters are believed to give luminescence signal even if they are read before, i.e. multiple reading may be possible under suitable conditions after single exposure. This was also checked for all the prepared dosemeters and it was found that Al2O3:C showed the least decrease of <2 %, followed by BaFCl:Eu of 15 % and K2Ca2(SO4)3:Eu with 20 %. Finally, Al2O3:C and BaFCl:Eu phosphors were also studied for their optical bleaching durations to which the respective signals get completely removed so that the phosphor can be re-used. It was observed that BaFCl:Eu is bleached faster and more easily than Al2O3:C. PMID:25646524

  6. Thermodynamic Equilibrium Calculations on Cd Transformation during Sewage Sludge Incineration.

    PubMed

    Liu, Jing-yong; Huang, Limao; Sun, Shuiyu; Ning, Xun'an; Kuo, Jiahong; Sun, Jian; Wang, Yujie; Xie, Wuming

    2016-06-01

    Thermodynamic equilibrium calculations were performed to reveal the distribution of cadmium during the sewage sludge incineration process. During sludge incineration in the presence of major minerals, such as SiO2, Al2O3 and CaO, the strongest effect was exerted by SiO2 on the Cd transformation compared with the effect of others. The stable solid product of CdSiO3 was formed easily with the reaction between Cd and SiO2, which can restrain the emissions of gaseous Cd pollutants. CdCl2 was formed more easily in the presence of chloride during incineration, thus, the volatilization of Cd was advanced by increasing chlorine content. At low temperatures, the volatilization of Cd was restrained due to the formation of the refractory solid metal sulfate. At high temperatures, the speciation of Cd was not affected by the presence of sulfur, but sulfur could affect the formation temperature of gaseous metals.

  7. Low dietary levels of Al, Pb and Cd may affect the non-enzymatic antioxidant capacity in caged honey bees (Apis mellifera).

    PubMed

    Gauthier, Maxime; Aras, Philippe; Jumarie, Catherine; Boily, Monique

    2016-02-01

    Several hypotheses have been proposed to explain the abnormally high mortality rate observed in bee populations in Europe and North America. While studies based on the effects of pesticides are paramount, the metals present in agroecosystems are often overlooked. Sources of metals are linked to the nature of soils and to agricultural practices, namely the use of natural or chemical nutrients as well as residual materials from waste-water treatment sludge. The aim of this study was to investigate the effects of metals on honey bees exposed for 10 days to environmentally realistic concentrations of Al, Pb and Cd (dissolved in syrup). The monitoring of syrup consumption combined with the quantification of metals in bees revealed the following order for metal bioconcentration ratios: Cd > Pb > Al. Alpha-tocopherol, metallothionein-like proteins (MTLPs) and lipid peroxidation were quantified. When bees were exposed to increasing amounts of Cd, a marked augmentation of MTLPs levels was found. Lead (Pb) and Cd caused an increase in α-tocopherol content, while alteration of lipid peroxidation was observed only with Al exposure. These findings raise concerns about the bioavailability and the additional threat posed by metals for pollinators in agricultural areas while providing new insights for potential use of the honey bee as a sentinel species for metal exposure. PMID:26421624

  8. Low dietary levels of Al, Pb and Cd may affect the non-enzymatic antioxidant capacity in caged honey bees (Apis mellifera).

    PubMed

    Gauthier, Maxime; Aras, Philippe; Jumarie, Catherine; Boily, Monique

    2016-02-01

    Several hypotheses have been proposed to explain the abnormally high mortality rate observed in bee populations in Europe and North America. While studies based on the effects of pesticides are paramount, the metals present in agroecosystems are often overlooked. Sources of metals are linked to the nature of soils and to agricultural practices, namely the use of natural or chemical nutrients as well as residual materials from waste-water treatment sludge. The aim of this study was to investigate the effects of metals on honey bees exposed for 10 days to environmentally realistic concentrations of Al, Pb and Cd (dissolved in syrup). The monitoring of syrup consumption combined with the quantification of metals in bees revealed the following order for metal bioconcentration ratios: Cd > Pb > Al. Alpha-tocopherol, metallothionein-like proteins (MTLPs) and lipid peroxidation were quantified. When bees were exposed to increasing amounts of Cd, a marked augmentation of MTLPs levels was found. Lead (Pb) and Cd caused an increase in α-tocopherol content, while alteration of lipid peroxidation was observed only with Al exposure. These findings raise concerns about the bioavailability and the additional threat posed by metals for pollinators in agricultural areas while providing new insights for potential use of the honey bee as a sentinel species for metal exposure.

  9. Structure-property relationships in an Al matrix Ca nanofilamentary composite conductor with potential application in high-voltage power transmission

    NASA Astrophysics Data System (ADS)

    Tian, Liang

    This study investigated the processing-structure-properties relationships in an Al/Ca composites using both experiments and modeling/simulation. A particular focus of the project was understanding how the strength and electrical conductivity of the composite are related to its microstructure in the hope that a conducting material with light weight, high strength, and high electrical conductivity can be developed to produce overhead high-voltage power transmission cables. The current power transmission cables (e.g., Aluminum Conductor Steel Reinforced (ACSR)) have acceptable performance for high-voltage AC transmission, but are less well suited for high-voltage DC transmission due to the poorly conducting core materials that support the cable weight. This Al/Ca composite was produced by powder metallurgy and severe plastic deformation by extrusion and swaging. The fine Ca metal powders have been produced by centrifugal atomization with rotating liquid oil quench bath, and a detailed study about the atomization process and powder characteristics has been conducted. The microstructure of Al/Ca composite was characterized by electron microscopy. Microstructure changes at elevated temperature were characterized by thermal analysis and indirect resistivity tests. The strength and electrical conductivity were measured by tensile tests and four-point probe resistivity tests. Predicting the strength and electrical conductivity of the composite was done by micro-mechanics-based analytical modeling. Microstructure evolution was studied by mesoscale-thermodynamics-based phase field modeling and a preliminary atomistic molecular dynamics simulation. The application prospects of this composite was studied by an economic analysis. This study suggests that the Al/Ca (20 vol. %) composite shows promise for use as overhead power transmission cables. Further studies are needed to measure the corrosion resistance, fatigue properties and energized field performance of this composite.

  10. SESAM modelocked Yb:CaGdAlO4 laser in the soliton modelocking regime with positive intracavity dispersion.

    PubMed

    Phillips, C R; Mayer, A S; Klenner, A; Keller, U

    2014-03-10

    We demonstrate femtosecond SESAM modelocking in the near-infrared by using cascaded quadratic nonlinearities (phase-mismatched second-harmonic generation, SHG), enabling soliton modelocking in the normal dispersion regime without any dispersion compensating elements. To obtain large and negative self-phase modulation (SPM) we use an intracavity LBO crystal, whose temperature and angles are optimized with respect to SPM, nonlinear losses, and self-starting characteristics. To support femtosecond pulses, we use the very promising Yb:CaGdAlO(4) (CALGO) gain material, operated in a bulk configuration. The LBO crystal provides sufficient negative SPM to compensate for its own GDD as well as the positive GDD and SPM from the gain crystal. The modelocked laser produces pulses of 114 fs at 1050 nm, with a repetition rate of 113 MHz (average output power 1.1 W). We perform a detailed theoretical study of this soliton modelocking regime with positive GDD, which clearly indicates the important design constraints in an intuitive and systematic way. In particular, due to its importance in avoiding multi-pulsed modelocking, we examine the nonlinear loss associated with the cascading process carefully and show how it can be suppressed in practice. With this modelocking regime, it should be possible to overcome the limits faced by current state of the art modelocked lasers in terms of dispersion compensation and nonlinearity management at high powers, suppression of Q-switching in compact GHz lasers, and enabling femtosecond soliton modelocking at very high repetition rates due to the high nonlinearities accessible via cascading combined with eliminating the need for intracavity dispersion compensation.

  11. Laboratory Study on Prevention of CaO-Containing ASTM "D-Type" Inclusions in Al-Deoxidized Low-Oxygen Steel Melts During Basic Slag Refining

    NASA Astrophysics Data System (ADS)

    Jiang, Min; Wang, Xin-Hua; Yang, Die; Lei, Shao-Long; Wang, Kun-Peng

    2015-12-01

    Present work was attempted to explore the possibility of preventing CaO-containing inclusions in Al-deoxidized low-oxygen special steel during basic slag refining, which were known as ASTM D-type inclusions. Based on the analysis on formation thermodynamics of CaO-containing inclusions, a series of laboratory experiments were designed and carried out in a vacuum induction furnace. During the experiments, slag/steel reaction equilibrium was intentionally suppressed with the aim to decrease the CaO contents in inclusions, which is different from ordinary concept that slag/steel reaction should be promoted for better control of inclusions. The obtained results showed that high cleanliness of steel was obtained in all the steel melts, with total oxygen contents varied between 0.0003 and 0.0010 pct. Simultaneously, formation of CaO-containing inclusions was successfully prohibited, and all the formed oxide inclusions were MgO-Al2O3 or/and Al2O3 in very small sizes of about 1 to 3 μm. And 90 pct to nearly 98 pct of them were wrapped by relative thicker MnS outer surface layers to produce dual-phased "(MgO-Al2O3) + MnS" or "Al2O3 + MnS" complex inclusions. Because of much better ductility of MnS, certain deformability of these complex inclusions can be expected which is helpful to improve fatigue resistance property of steel. Only very limited number of singular MnS inclusions were with sizes larger than 13 μm, which were formed during solidification because of. In the end, formation of oxide inclusions in steel was qualitatively evaluated and discussed.

  12. [Research on the Relationship between Surface Structure and Fluorescence Intensity of Ca(1-x)Al2Si2O8 : Eu(x)].

    PubMed

    He, Xiao; Zhang, Li-sheng; Zu, En-dong; Yang, Xiao-yun; Dong, Kun

    2016-01-01

    Ca(1-x)Al2Si2O8 : Eu(x)(x = 0, 0.01, 0.05, 0.15) were synthesized by solid-state reaction respectively at 1 150, 1 250 1350 and 1 450 degrees C. With X-ray diffraction(XRD), Raman spectroscopy(Raman), photoluminescence spectroscopy(PL) and X-ray fluorescence spectrometer(XRF), the relationship between surface structure and fluorescence intensity of Ca(1-x) Al2Si2O8: Eu(x) were studied. XRD and Raman results show that, CaAl2Si2O8 anorthite single-phase has formed gradually along with the temperature rising in the process of synthesis. Raman spectroscopy is clear that when the Eu doping amount is the same, Si-O amorphous phase disappear gradually and the CaAl2Si2O8 phase form gradually with the temperature increases. As the temperature increases, vibration peaks position silicon oxygen tetrahedron shift to lower wave number. When 1 450 degrees C, the temperature is too high to destroy the structure of silicon oxygen tetrahedron. At the same time, there is a broadening amorphous peak appears in Raman spectroscopy. The procedure of Al to replace Si is hindered with Eu doped in. It is the result that the peak at 1 620 cm(-1) decreases after the first increases. The change of surface structure associated with the scattering amount of Eu. PL and XRF results show that: as the temperature increases, the amount of Eu atom scattering on the material surface increases gradually, this change lead to the fluorescence intensity raise. Therefore, there is proportional relationship between the fluorescence intensity of the samples and the number of samples per unit surface area of Eu atoms. PMID:27228758

  13. Al15Ge4Ni3: A new intergrowth structure with Cu3Au- and CaF2-type building blocks

    NASA Astrophysics Data System (ADS)

    Reichmann, Thomas L.; Jandl, Isabella; Effenberger, Herta S.; Herzig, Peter; Richter, Klaus W.

    2015-05-01

    The new ternary compound Al15Ge4Ni3 (τ2 in the system Al-Ge-Ni) was synthesized in single crystalline form by a special annealing procedure from samples located in the three phase fields [L+Al+τ2] and [L+Ge+τ2]. The crystal structure of Al15Ge4Ni3 was determined by single-crystal X-ray diffraction. The compound crystallizes in a new structure type in space group I4¯3m, Pearson Symbol cI88, cubic lattice parameter a=11.405(1) Å. Phase diagram investigations indicate stoichiometric composition without considerable homogeneity range; τ2 melts peritectically at T=444 °C. The crystal structure of Al15Ge4Ni3 shows a unique combination of simple Cu3Au- and CaF2-type building blocks: a three dimensional network of CaF2-type units, formed by Ni and Al atoms, is interspaced by clusters (Al6Ge8) resembling unit cells of the Cu3Au-type. Both structural motifs are connected by Al-Ge bonds. The ground state energy of the compound was obtained by DFT calculations and the densities of states were analyzed in detail. In addition, electron density maps were calculated in four different sections through the unit cell using the full potential linearized augmented plane-wave (FLAPW) method. The bonding situation in Al15Ge4Ni3 was discussed combining results from electronic calculations with the analysis of the coordination of atoms.

  14. Rectification and tunneling effects enabled by Al2O3 atomic layer deposited on back contact of CdTe solar cells

    NASA Astrophysics Data System (ADS)

    Liang, Jun; Lin, Qinxian; Li, Hao; Su, Yantao; Yang, Xiaoyang; Wu, Zhongzhen; Zheng, Jiaxin; Wang, Xinwei; Lin, Yuan; Pan, Feng

    2015-07-01

    Atomic layer deposition (ALD) of Aluminum oxide (Al2O3) is employed to optimize the back contact of thin film CdTe solar cells. Al2O3 layers with a thickness of 0.5 nm to 5 nm are tested, and an improved efficiency, up to 12.1%, is found with the 1 nm Al2O3 deposition, compared with the efficiency of 10.7% without Al2O3 modification. The performance improvement stems from the surface modification that optimizes the rectification and tunneling of back contact. The current-voltage analysis indicates that the back contact with 1 nm Al2O3 maintains large tunneling leakage current and improves the filled factor of CdTe cells through the rectification effect. XPS and capacitance-voltage electrical measurement analysis show that the ALD-Al2O3 modification layer features a desired low-density of interface state of 8 × 1010 cm-2 by estimation.

  15. Rectification and tunneling effects enabled by Al{sub 2}O{sub 3} atomic layer deposited on back contact of CdTe solar cells

    SciTech Connect

    Liang, Jun; Lin, Qinxian; Li, Hao; Su, Yantao; Yang, Xiaoyang; Wu, Zhongzhen; Zheng, Jiaxin; Wang, Xinwei; Lin, Yuan; Pan, Feng

    2015-07-06

    Atomic layer deposition (ALD) of Aluminum oxide (Al{sub 2}O{sub 3}) is employed to optimize the back contact of thin film CdTe solar cells. Al{sub 2}O{sub 3} layers with a thickness of 0.5 nm to 5 nm are tested, and an improved efficiency, up to 12.1%, is found with the 1 nm Al{sub 2}O{sub 3} deposition, compared with the efficiency of 10.7% without Al{sub 2}O{sub 3} modification. The performance improvement stems from the surface modification that optimizes the rectification and tunneling of back contact. The current-voltage analysis indicates that the back contact with 1 nm Al{sub 2}O{sub 3} maintains large tunneling leakage current and improves the filled factor of CdTe cells through the rectification effect. XPS and capacitance-voltage electrical measurement analysis show that the ALD-Al{sub 2}O{sub 3} modification layer features a desired low-density of interface state of 8 × 10{sup 10 }cm{sup −2} by estimation.

  16. Tailor-Made Core-Shell CaO/TiO2-Al2O3 Architecture as a High-Capacity and Long-Life CO2 Sorbent.

    PubMed

    Peng, Weiwei; Xu, Zuwei; Luo, Cong; Zhao, Haibo

    2015-07-01

    CaO-based sorbents are widely used for CO2 capture, steam methane reforming, and gasification enhancement, but the sorbents suffer from rapid deactivation during successive carbonation/calcination cycles. This research proposes a novel self-assembly template synthesis (SATS) method to prepare a hierarchical structure CaO-based sorbent, Ca-rich, Al2O3-supported, and TiO2-stabilized in a core-shell microarchitecture (CaO/TiO2-Al2O3). The cyclic CO2 capture performance of CaO/TiO2-Al2O3 is compared with those of pure CaO and CaO/Al2O3. CaO/TiO2-Al2O3 sorbent achieved superior and durable CO2 capture capacity of 0.52 g CO2/g sorbent after 20 cycles under the mild calcination condition and retained a high-capacity and long-life performance of 0.44 g CO2/g sorbent after 104 cycles under the severe calcination condition, much higher than those of CaO and CaO/Al2O3. The microstructure characterization of CaO/TiO2-Al2O3 confirmed that the core-shell structure of composite support effectively inhibited the reaction between active component (CaO particles) and main support (Al2O3 particles) by TiO2 addition, which contributed to its properties of high reactivity, thermal stability, mechanical strength, and resistance to agglomeration and sintering.

  17. Tailor-Made Core-Shell CaO/TiO2-Al2O3 Architecture as a High-Capacity and Long-Life CO2 Sorbent.

    PubMed

    Peng, Weiwei; Xu, Zuwei; Luo, Cong; Zhao, Haibo

    2015-07-01

    CaO-based sorbents are widely used for CO2 capture, steam methane reforming, and gasification enhancement, but the sorbents suffer from rapid deactivation during successive carbonation/calcination cycles. This research proposes a novel self-assembly template synthesis (SATS) method to prepare a hierarchical structure CaO-based sorbent, Ca-rich, Al2O3-supported, and TiO2-stabilized in a core-shell microarchitecture (CaO/TiO2-Al2O3). The cyclic CO2 capture performance of CaO/TiO2-Al2O3 is compared with those of pure CaO and CaO/Al2O3. CaO/TiO2-Al2O3 sorbent achieved superior and durable CO2 capture capacity of 0.52 g CO2/g sorbent after 20 cycles under the mild calcination condition and retained a high-capacity and long-life performance of 0.44 g CO2/g sorbent after 104 cycles under the severe calcination condition, much higher than those of CaO and CaO/Al2O3. The microstructure characterization of CaO/TiO2-Al2O3 confirmed that the core-shell structure of composite support effectively inhibited the reaction between active component (CaO particles) and main support (Al2O3 particles) by TiO2 addition, which contributed to its properties of high reactivity, thermal stability, mechanical strength, and resistance to agglomeration and sintering. PMID:26047026

  18. Characterization of Ti6Al7Nb alloy foams surface treated in aqueous NaOH and CaCl2 solutions.

    PubMed

    Bütev, Ezgi; Esen, Ziya; Bor, Şakir

    2016-07-01

    Ti6Al7Nb alloy foams having 53-73% porosity were manufactured via evaporation of magnesium space holders. A bioactive 1µm thick sodium hydrogel titanate layer, NaxH2-xTiyO2y+1, formed after 5M NaOH treatment, was converted to crystalline sodium titanate, Na2TiyO2y+1, as a result of post-heat treatment. On the other hand, subsequent CaCl2 treatment of NaOH treated specimens induced calcium titanate formation. However, heat treatment of NaOH-CaCl2 treated specimens led to the loss of calcium and disappearance of the titanate phase. All of the aforementioned surface treatments reduced yield strengths due to the oxidation of the cell walls of the foams, while elastic moduli remained mostly unchanged. Accordingly, equiaxed dimples seen on the fracture surfaces of as-manufactured foams turned into relatively flat and featureless fracture surfaces after surface treatments. On the other hand, Ca- and Na-rich coating preserved their mechanical stabilities and did not spall during fracture. The relation between mechanical properties of foams and macro-porosity fraction were found to obey a power law. The foams with 63 and 73% porosity met the desired biocompatibility requirements with fully open pore structures and elastic moduli similar to that of bone. In vitro tests conducted in simulated body fluid (SBF) showed that NaOH-heat treated surfaces exhibit the highest bioactivity and allow the formation of Ca-P rich phases having Ca/P ratio of 1.3 to form within 5 days. Although Ca-P rich phases formed only after 15 days on NaOH-CaCl2 treated specimens, the Ca/P ratio was closer to that of apatite found in bone. PMID:26807769

  19. Lunar highland rocks - Element partitioning among minerals. II - Electron microprobe analyses of Al, P, Ca, Ti, Cr, Mn and Fe in olivine

    NASA Technical Reports Server (NTRS)

    Smith, J. V.; Hansen, E. C.; Steele, I. M.

    1980-01-01

    Lunar olivines from anorthosites, granulitic impactites, and rocks in the Mg-rich plutonic trend were subjected to electron probe measurements for Al, P, Ca, Ti, Cr and Mn, which show that the FeO/MnO ratio for lunar olivines lies between 80 and 110 with little difference among the rock types. The low values of Ca in lunar olivines indicate slow cooling to subsolidus temperatures, with blocking temperatures of about 750 C for 67667 and 1000 C for 60255,73-alpha determined by the Finnerty and Boyd (1978) experiments. An important paradox is noted in the low Ti content of Fe-rich olivines from anorthosites, although both Ti and Fe tend to become enriched in liquid during fractional distillation. Except for Ca and Mn, olivine from anorthosites has lower minor element values than other rock types. Formation from a chemically distinct system is therefore implied.

  20. Plasma-sprayed CaTiSiO5 ceramic coating on Ti-6Al-4V with excellent bonding strength, stability and cellular bioactivity

    PubMed Central

    Wu, Chengtie; Ramaswamy, Yogambha; Liu, Xuanyong; Wang, Guocheng; Zreiqat, Hala

    2008-01-01

    Novel Ca-Si-Ti-based sphene (CaTiSiO5) ceramics possess excellent chemical stability and cytocompatibility. The aim of this study was to prepare sphene coating on titanium alloy (Ti-6Al-4V) for orthopaedic applications using the plasma spray method. The phase composition, surface and interface microstructure, coating thickness, surface roughness and bonding strength of the plasma-sprayed sphene coating were analysed using X-ray diffraction, scanning electron microscopy, atomic force microscopy and the standard mechanical testing of the American Society for Testing and Materials, respectively. The results indicated that sphene coating was obtained with a uniform and dense microstructure at the interface of the Ti-6Al-4V surface and the thickness and surface roughness of the coating were approximately 150 and 10 μm, respectively. Plasma-sprayed sphene coating on Ti-6Al-4V possessed a significantly improved bonding strength and chemical stability compared with plasma-sprayed hydroxyapatite (HAp) coating. Plasma-sprayed sphene coating supported human osteoblast-like cell (HOB) attachment and significantly enhanced HOB proliferation and differentiation compared with plasma-sprayed HAp coating and uncoated Ti-6Al-4V. Taken together, plasma-sprayed sphene coating on Ti-6Al-4V possessed excellent bonding strength, chemical stability and cellular bioactivity, indicating its potential application for orthopaedic implants. PMID:18664431

  1. Plasma-sprayed CaTiSiO5 ceramic coating on Ti-6Al-4V with excellent bonding strength, stability and cellular bioactivity.

    PubMed

    Wu, Chengtie; Ramaswamy, Yogambha; Liu, Xuanyong; Wang, Guocheng; Zreiqat, Hala

    2009-02-01

    Novel Ca-Si-Ti-based sphene (CaTiSiO5) ceramics possess excellent chemical stability and cytocompatibility. The aim of this study was to prepare sphene coating on titanium alloy (Ti-6Al-4V) for orthopaedic applications using the plasma spray method. The phase composition, surface and interface microstructure, coating thickness, surface roughness and bonding strength of the plasma-sprayed sphene coating were analysed using X-ray diffraction, scanning electron microscopy, atomic force microscopy and the standard mechanical testing of the American Society for Testing and Materials, respectively. The results indicated that sphene coating was obtained with a uniform and dense microstructure at the interface of the Ti-6Al-4V surface and the thickness and surface roughness of the coating were approximately 150 and 10 microm, respectively. Plasma-sprayed sphene coating on Ti-6Al-4V possessed a significantly improved bonding strength and chemical stability compared with plasma-sprayed hydroxyapatite (HAp) coating. Plasma-sprayed sphene coating supported human osteoblast-like cell (HOB) attachment and significantly enhanced HOB proliferation and differentiation compared with plasma-sprayed HAp coating and uncoated Ti-6Al-4V. Taken together, plasma-sprayed sphene coating on Ti-6Al-4V possessed excellent bonding strength, chemical stability and cellular bioactivity, indicating its potential application for orthopaedic implants.

  2. Directional solidification, thermo-mechanical and optical properties of (Mg(x)Ca(1-x))(3)Al(2)Si(3)O(12) glasses doped with Nd(3+) ions.

    PubMed

    Sola, D; Conejos, D; Martínez de Mendivil, J; Ortega-San-Martín, L; Lifante, G; Peña, J I

    2015-10-01

    In this work glass rods of (Mg(x)Ca(1-x))(3)Al(2)Si(3)O(12) (x = 0, 0.5 and 1) doped with 1 wt% Nd(2)O(3) were produced by the laser floating zone technique. Thermo-mechanical and spectroscopic properties have been evaluated. The three glass samples present good thermo-mechanical properties, with similar hardness, toughness and glass transition temperatures. The spectroscopic characterization shows spectral shifts in absorption and emission spectra. These spectral shifts together with Judd-Ofelt intensity parameters and ionic packing ratio have been used to investigate the local structure surrounding the Nd(3+) ions and the covalency of the Nd-O bond. All obtained results agree and confirm the higher covalency of the Nd-O bond in the Ca(3)Al(2)Si(3)O(12) glass.

  3. (CaO · Al2O3 · SiO2): Eu phosphors for violet/ultraviolet-to-white radiation conversion

    NASA Astrophysics Data System (ADS)

    Gurin, N. T.; Paksyutov, K. V.; Terent'ev, M. A.; Shirokov, A. V.

    2012-02-01

    (2CaO · 0.5Al2O3 · 5SiO2): Eu and (CaO · 0.2Al2O3 · SiO2): Eu phosphors doped with B2O3 in an amount of 3 wt % are obtained by direct solid-phase synthesis at 1350°C. When excited by LED radiation with a maximum at 380 nm, these phosphors emit white light with color coordinates, which are close to those in the EBU and NTSC TV standards and fall into the field of white light corresponding to light warning systems according to the International Commission on Illumination (CIE).

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

    NASA Technical Reports Server (NTRS)

    Zaplatynsky, Isidor

    1988-01-01

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

  5. Directional solidification, thermo-mechanical and optical properties of (Mg(x)Ca(1-x))(3)Al(2)Si(3)O(12) glasses doped with Nd(3+) ions.

    PubMed

    Sola, D; Conejos, D; Martínez de Mendivil, J; Ortega-San-Martín, L; Lifante, G; Peña, J I

    2015-10-01

    In this work glass rods of (Mg(x)Ca(1-x))(3)Al(2)Si(3)O(12) (x = 0, 0.5 and 1) doped with 1 wt% Nd(2)O(3) were produced by the laser floating zone technique. Thermo-mechanical and spectroscopic properties have been evaluated. The three glass samples present good thermo-mechanical properties, with similar hardness, toughness and glass transition temperatures. The spectroscopic characterization shows spectral shifts in absorption and emission spectra. These spectral shifts together with Judd-Ofelt intensity parameters and ionic packing ratio have been used to investigate the local structure surrounding the Nd(3+) ions and the covalency of the Nd-O bond. All obtained results agree and confirm the higher covalency of the Nd-O bond in the Ca(3)Al(2)Si(3)O(12) glass. PMID:26480149

  6. The [17.0] 2Π1/2← X 2Π1/2 system of AlCa

    NASA Astrophysics Data System (ADS)

    Fabbi, Jacqueline C.; Langenberg, Jon D.; Morse, Michael D.

    2000-04-01

    Laser-induced fluorescence spectroscopy has been used to study supersonically cooled AlCa. This study investigates under higher resolution (0.007 cm-1) a single band previously studied and tentatively assigned as the (0-0) vibrational transition of the [17.0] 2Δ3/2(?)← X 2Π1/2 system of AlCa. The resolution of the rotational structure in the present study enabled a definite assignment as a 2Π1/2← 2Π1/2 transition. Analysis of the spectrum gives B0'=0.096685(19) cm-1, ( p+2 q)'=-0.013078(370) cm -1, and B0″=0.105518(20) cm -1. These convert to ground and excited state bond lengths of r0″=3.14942(30) and r0'=3.29014(32) Å, respectively.

  7. Structural characterization of Nd-doped Hf-zirconolite Ca 1-xNd xHfTi 2-xAl xO 7 ceramics

    NASA Astrophysics Data System (ADS)

    Caurant, Daniel; Loiseau, Pascal; Bardez, Isabelle

    2010-12-01

    Because of its high incorporation capacity and of the high thermal neutron capture cross-section of hafnium, Hf-zirconolite (CaHfTi 2O 7) ceramic can be envisaged as a potential waste form for minor actinides (Np, Am, Cm) and plutonium immobilization. In this work, Nd-doped Hf-zirconolite Ca 1-xNd xHfTi 2-xAl xO 7 ( x = 0; 0.01 and 0.2) ceramics have been prepared by solid state reaction. Neodymium has been used as trivalent actinide surrogate. The ceramic samples structure has been studied by X-ray diffraction and refined by the Rietveld method. This revealed that Nd 3+ ions only enter the Ca site, whereas part of Hf 4+ ions substitute titanium into Ti(1) sites and Al 3+ ions mainly occupy the Ti(2) split sites and Ti(3) sites of the zirconolite structure. Using various spectroscopic techniques (electron spin resonance, optical absorption and fluorescence), the environment of Nd 3+ cations in Hf-zirconolite has been studied and compared with that of Nd 3+ cations in Zr-zirconolite (CaZrTi 2O 7). Different local environments of Nd 3+ cations have been detected in Hf-zirconolite that can be attributed to the existence of an important disorder around Nd in the Ca site probably due to the statistical occupancy of the next nearest cationic site of neodymium (a split Ti site) by Ti 4+, Al 3+ cations and vacancies. No significant differences were observed concerning Nd 3+ cations environment and distribution in Hf- and Zr-zirconolite ceramics.

  8. Superconductivity up to 114 K in the Bi-Al-Ca-Sr-Cu-O compound system without rare-earth elements

    NASA Technical Reports Server (NTRS)

    Chu, C. W.; Bechtold, J.; Gao, L.; Hor, P. H.; Huang, Z. J.

    1988-01-01

    Stable superconductivity up to 114 K has been reproducibly detected in Bi-Al-Ca-Sr-Cu-O multiphase systems without any rare-earth elements. Pressure has only a slight positive effect on T(c). These observations provide an extra material base for the study of the mechanism of high-temperature superconductivity and also the prospect of reduced material cost for future applications of superconductivity.

  9. SiO 2-CaO-B 2O 3-Al 2O 3 ceramic glaze as sealant for planar ITSOFC

    NASA Astrophysics Data System (ADS)

    Zheng, R.; Wang, S. R.; Nie, H. W.; Wen, T.-L.

    A series of ceramic glazes based on the SiO 2-CaO-B 2O 3-Al 2O 3 system as sealant for intermediate temperature solid oxide fuel cell (ITSOFC) were investigated. Different ratios of B 2O 3/SiO 2 and Al 2O 3/CaO were investigated to control softening process, phase separation, and crystallization. When B 2O 3/SiO 2 ratio was in the range of 0.14-0.27, the glazes showed good wetting and bonding behavior with both 8 mol% yttria-stabilized zirconia (8YSZ) electrolyte and stainless steel interconnect which could satisfy the sealing demand at 850 °C. And the dimension stability can be kept for over 100 h by introducing ceramic felt and controlling the glazes viscosity in the range of 10 4 to 10 6 Pa s. By means of controlling Al 2O 3/CaO ratio in the range of 0.4-0.68, phase separation and crystallization were restrained effectively. After holding at 850 °C for 100 h, non-crystalline network in the glazes could be found, and a suitable viscous flow could well relax thermal stress. The sealing was effective even after 10 thermal cycles. Element analysis showed a good chemical stability at the ceramic glazes/stainless steel interconnect and ceramic glazes/8YSZ electrolyte interfaces.

  10. Uwachib'alil Qach'ab'al--Asi se Ilustra mi Palabra (Illustrating My Words). [CD-ROM].

    ERIC Educational Resources Information Center

    Academy for Educational Development, Washington, DC.

    This CD-ROM is part of an interactive and dynamic multimedia package of information and games for learning K'iche' and Ixil. This CD-ROM contains a database of 3,000 culturally-relevant vocabulary words in K'iche', Ixil, and Spanish, with appropriate illustrations that describe traditional Mayan rituals, foods, beliefs, clothing, and other topics.…

  11. New insights into organic-inorganic hybrid perovskite CH3NH3PbI3 nanoparticles. An experimental and theoretical study of doping in Pb2+ sites with Sn2+, Sr2+, Cd2+ and Ca2+

    NASA Astrophysics Data System (ADS)

    Navas, Javier; Sánchez-Coronilla, Antonio; Gallardo, Juan Jesús; Cruz Hernández, Norge; Piñero, Jose Carlos; Alcántara, Rodrigo; Fernández-Lorenzo, Concha; de Los Santos, Desireé M.; Aguilar, Teresa; Martín-Calleja, Joaquín

    2015-03-01

    This paper presents the synthesis of the organic-inorganic hybrid perovskite, CH3NH3PbI3, doped in the Pb2+ position with Sn2+, Sr2+, Cd2+ and Ca2+. The incorporation of the dopants into the crystalline structure was analysed, observing how the characteristics of the dopant affected properties such as the crystalline phase, emission and optical properties. XRD showed how doping with Sn2+, Sr2+ and Cd2+ did not modify the normal tetragonal phase. When doping with Ca2+, the cubic phase was obtained. Moreover, DR-UV-Vis spectroscopy showed how the band gap decreased with the dopants, the values following the trend Sr2+ < Cd2+ < Ca2+ < CH3NH3PbI3 ~ Sn2+. The biggest decrease was generated by Sr2+, which reduced the CH3NH3PbI3 value by 4.5%. In turn, cathodoluminescence (CL) measurements confirmed the band gap obtained. Periodic-DFT calculations were performed to understand the experimental structures. The DOS analysis confirmed the experimental results obtained using UV-Vis spectroscopy, with the values calculated following the trend Sn2+ ~ Pb2+ > Cd2+ > Sr2+ for the tetragonal structure and Pb2+ > Ca2+ for the cubic phase. The electron localization function (ELF) analysis showed similar electron localizations for undoped and Sn2+-doped tetragonal structures, which were different from those doped with Sr2+ and Cd2+. Furthermore, when Cd2+ was incorporated, the Cd-I interaction was strengthened. For Ca2+ doping, the Ca-I interaction had a greater ionic nature than Cd-I. Finally, an analysis based on the non-covalent interaction (NCI) index is presented to determine the weak-type interactions of the CH3NH3 groups with the dopant and I atoms. To our knowledge, this kind of analysis with these hybrid systems has not been performed previously.This paper presents the synthesis of the organic-inorganic hybrid perovskite, CH3NH3PbI3, doped in the Pb2+ position with Sn2+, Sr2+, Cd2+ and Ca2+. The incorporation of the dopants into the crystalline structure was analysed

  12. Excellent stability of plasma-sprayed bioactive Ca 3ZrSi 2O 9 ceramic coating on Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Liang, Ying; Xie, Youtao; Ji, Heng; Huang, Liping; Zheng, Xuebin

    2010-05-01

    In this work, novel zirconium incorporated Ca-Si based ceramic powder Ca 3ZrSi 2O 9 was synthesized. The aim of this study was to fabricate Ca 3ZrSi 2O 9 coating onto Ti-6Al-4V substrate using atmospheric plasma-spraying technology and to evaluate its potential applications in the fields of orthopedics and dentistry. The phase composition, surface morphologies of the coating were examined by XRD and SEM, which revealed that the Ca 3ZrSi 2O 9 coating was composed of grains around 100 nm and amorphous phases. The bonding strength between the coating and the substrate was 28 ± 4 MPa, which is higher than that of traditional HA coating. The dissolution rate of the coating was assessed by monitoring the ions release and mass loss after immersion in the Tris-HCl buffer solution. The in vitro bioactivity of the coating was determined by observing the formation of apatite on its surface in simulated body fluids. It was found that the Ca 3ZrSi 2O 9 coating possessed both excellent chemical stability and good apatite-formation ability, suggesting its potential use as bone implants.

  13. Structural and optical characterizations of Ca2Al2SiO7:Ce3+, Mn2+ nanoparticles produced via a hybrid route

    NASA Astrophysics Data System (ADS)

    Teixeira, V. C.; Montes, P. J. R.; Valerio, M. E. G.

    2014-07-01

    Pure, Ce3+ doped and Ce3+ and Mn2+ co-doped Ca2Al2SiO7 ceramic powders were prepared by two different methodologies which are the proteic sol-gel process and a new hybrid route combining the proteic sol-gel with solid state reaction processes. The second one is an eco-friendly method because it uses natural raw materials in replacement of the metal alkoxides used in the traditional sol-gel routes. X-ray diffraction showed that Ca2Al2SiO7 crystalline phase was obtained for both preparations. Differential thermal analysis indicated that the exothermic event around 850 °C, for sample produced by proteic sol-gel method, and around 927 °C, for ceramics prepared by hybrid synthesis, can be associated to crystallization of Ca2Al2SiO7. Transmission electron microscope indicates that regular and spherical nanoparticles were obtained with average sizes of about 12 nm. The Scherrer’s method was used to determine the average crystallite sizes and it was shown that nanometric crystallites were obtained of about 74 nm for samples produced via hybrid route. For all the single phase samples, the crystallite sizes are about the same and that agrees with TEM results. Diffuse optical reflectance measurements were used to estimate the Ca2Al2SiO7 optical band gap and the obtained value is about 6 eV, photoluminescence (PL) spectra presented typical emissions of Ce3+ and Mn2+ ions. Upon excitation at 352 nm the emission spectra showed a broad band centered at 415 nm due to the Ce3+ 4f1 → 5d1 typical transition. This emission is resonant with Mn2+ excitation and it transfers energy to Mn ions generating a second broad emission band centered at 620 nm due to the Mn2+. The PL results were used to obtain, as a fist approach, the Ce3+ energy levels diagram and, using the Tanabe-Sugano diagrams, the transitions due to the Mn2+ were calculated. X-ray excited optical luminescence measurements showed the same emission spectra as the PL emission spectra. Luminescence lifetime decay

  14. High pressure synthesis and crystal structure of a ternary superconductor Ca{sub 2}Al{sub 3}Si{sub 4} containing layer structured calcium sub-network isomorphous with black phosphorus

    SciTech Connect

    Tanaka, Masashi; Zhang, Shuai; Tanaka, Yuki; Inumaru, Kei; Yamanaka, Shoji

    2013-02-15

    The Zintl compound CaAl{sub 2}Si{sub 2} is peritectically decomposed to a mixture of Ca{sub 2}Al{sub 3}Si{sub 4} and aluminum metal at temperatures above 600 Degree-Sign C under a pressure of 5 GPa. The new ternary compound Ca{sub 2}Al{sub 3}Sl{sub 4} crystalizes with the space group Cmc2{sub 1} and the lattice parameters a=5.8846(8), b=14.973(1), and c=7.7966(5) A. The structure is composed of aluminum silicide framework [Al{sub 3}Si{sub 4}] and layer structured [Ca{sub 2}] network interpenetrating with each other. The electron probe microanalysis (EPMA) shows the formation of solid solutions Ca{sub 2}Al{sub 3-x}Si{sub 4+x} (x<0.6). The layer structured [Ca{sub 2}] sub-network is isomorphous with black phosphorus. The new ternary compound shows superconductivity with a transition temperature (T{sub c}) of 6.4 K. The band structure calculation suggests that the superconductivity should occur through the conduction bands mainly composed of 3p orbitals of the aluminum silicide framework. - Graphical abstract: A new ternary superconductor Ca{sub 2}Al{sub 3}Si{sub 4} has been prepared under high pressure and high temperature conditions, which includes layer structured calcium sub-network isomorphous with black phosphorus. Highlights: Black-Right-Pointing-Pointer A typical Zintl compound CaAl{sub 2}Si{sub 2} melts congruently at ambient pressure. Black-Right-Pointing-Pointer Under high pressure CaAl{sub 2}Si{sub 2} decomposes to Ca{sub 2}Al{sub 3}Si{sub 4} and Al at {approx}600 Degree-Sign C. Black-Right-Pointing-Pointer Ca{sub 2}Al{sub 3}Si{sub 4} contains Ca sub-network isomorphous with black phosphorus. Black-Right-Pointing-Pointer Ca{sub 2}Al{sub 3}Si{sub 4} shows superconductivity with a transition temperature of 6.4 K.

  15. Properties of transparent (Gd,Lu)3(Al,Ga)5O12:Ce ceramic with Mg, Ca and Ce co-dopants

    NASA Astrophysics Data System (ADS)

    Wang, Yimin; Baldoni, Gary; Brecher, Charles; Rhodes, William H.; Shirwadkar, Urmila; Glodo, Jarek; Shah, Ishaan; Ji, Chuncheng

    2015-08-01

    Cerium activated mixed lutetium/gadolinium- and aluminum/gallium-based garnets have great potential as host scintillators for medical imaging applications. (Gd,Lu)3(Al,Ga)5O12:Ce and denoted as GLuGAG feature high effective atomic number and good light yield, which make it particularly attractive for Positron Emission Tomography (PET) and other γ-ray detection applications. For PET application, rapid decay and good timing resolution are extremely important. Most Ce-doped mixed garnet materials such as GLuGAG:Ce, have their main decay component at around 80 ns. However, it has been reported that the decays of some single crystal scintillators (e.g., LSO and GGAG) can be effectively accelerated by codoping with selected additives such as Ca, Mg and B. In this study, transparent polycrystalline (Gd,Lu)3(Al,Ga)5O12:Ce ceramics codoped with Ca or Mg or additional Ce, were fabricated by the sinter-HIP approach. It was found the transmission of the ceramics are closely related to the microstructure of the ceramics. As the co-dopant levels increase, 2nd phase occurs in the ceramic and thus transparency of the ceramic decreases. Ca and Mg co-doping in GLuGAG:Ce ceramic effectively accelerate decays of GLuGAG:Ce ceramics at a cost of light output. However, additional Ce doping in the GLuGAG:Ce has no benefit on improving decay time but, on the other hand, reduces transmission, light output. The mechanism under the different scintillation behaviors with Mg, Ca and Ce dopants are discussed. The results suggest that decay time of GLuGAG:Ce ceramics can be effectively tailored by co-doping GLuGAG:Ce ceramic with Mg and Ca for applications with optimal timing resolution.

  16. Improvement in dielectric and mechanical performance of CaCu3.1Ti4O12.1 by addition of Al2O3 nanoparticles.

    PubMed

    Puchmark, Chompoonuch; Rujijanagul, Gobwute

    2012-01-05

    The properties of CaCu3.1Ti4O12.1 [CC3.1TO] ceramics with the addition of Al2O3 nanoparticles, prepared via a solid-state reaction technique, were investigated. The nanoparticle additive was found to inhibit grain growth with the average grain size decreasing from approximately 7.5 μm for CC3.1TO to approximately 2.0 μm for the unmodified samples, while the Knoop hardness value was found to improve with a maximum value of 9.8 GPa for the 1 vol.% Al2O3 sample. A very high dielectric constant > 60,000 with a low loss tangent (approximately 0.09) was observed for the 0.5 vol.% Al2O3 sample at 1 kHz and at room temperature. These data suggest that nanocomposites have a great potential for dielectric applications.

  17. Improvement in dielectric and mechanical performance of CaCu3.1Ti4O12.1 by addition of Al2O3 nanoparticles

    PubMed Central

    2012-01-01

    The properties of CaCu3.1Ti4O12.1 [CC3.1TO] ceramics with the addition of Al2O3 nanoparticles, prepared via a solid-state reaction technique, were investigated. The nanoparticle additive was found to inhibit grain growth with the average grain size decreasing from approximately 7.5 μm for CC3.1TO to approximately 2.0 μm for the unmodified samples, while the Knoop hardness value was found to improve with a maximum value of 9.8 GPa for the 1 vol.% Al2O3 sample. A very high dielectric constant > 60,000 with a low loss tangent (approximately 0.09) was observed for the 0.5 vol.% Al2O3 sample at 1 kHz and at room temperature. These data suggest that nanocomposites have a great potential for dielectric applications. PMID:22221316

  18. Visible light CrO4(2-) reduction using the new CuAlO2/CdS hetero-system.

    PubMed

    Brahimi, R; Bessekhouad, Y; Nasrallah, N; Trari, M

    2012-06-15

    In this study, 64% of hexavalent chromium Cr(VI) reduction from the initial concentration (10(-4) M) is reported under visible light using the (CuAlO(2)/CdS) hetero-system. In this new hetero-system, low doped CuAlO(2) delafossite, synthesized by sol-gel works as an electrons reservoir with a wide space charge region (440 nm). In this case, the electron transfer to chromate is mediated via the hexagonal CdS variety, whose conduction band level is at -1.08 V with respect to the saturated calomel electrode which is more negative than the CrO(4)(2-)/Cr(3+) level. This high reduction rate is achieved under optimized pH and CuAlO(2) percentage. Moreover, salicylic acid gives the best performance among hole scavengers and CuAlO(2) approaches 100% photostability at pH 7.5. The photo-catalytic process follows a pseudo first order kinetic with a half life of 2h. The reaction products are identified by UV-visible spectrophotometry and linear voltametry at a platinum rotating electrode. The results reveal the presence of Cr(3+) after irradiation. PMID:22503216

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

    PubMed

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

    2013-01-21

    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 (Al(2)O(3))(x)(Na(2)O)(0.11-x)(CaO)(0.445)(P(2)O(5))(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 (27)Al 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. % Al(2)O(3) the density starts to decrease. Neutron diffraction data show a concomitant change in the aluminium speciation, which is confirmed by (27)Al 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 Al(2)O(3) content is increased beyond 3 mol. %.

  20. Effects of inorganic acids and divalent hydrated metal cations (Mg(2+), Ca(2+), Co(2+), Ni(2+)) on γ-AlOOH sol-gel process.

    PubMed

    Zhang, Jian; Xia, Yuguo; Zhang, Li; Chen, Dairong; Jiao, Xiuling

    2015-11-01

    In-depth understanding of the sol-gel process plays an essential role in guiding the preparation of new materials. Herein, the effects of different inorganic acids (HCl, HNO3 and H2SO4) and divalent hydrated metal cations (Mg(2+), Ca(2+), Co(2+), Ni(2+)) on γ-AlOOH sol-gel process were studied based on experiments and density functional theory (DFT) calculations. In these experiments, the sol originating from the γ-AlOOH suspension was formed only with the addition of HCl and HNO3, but not with H2SO4. Furthermore, the DFT calculations showed that the strong adsorption of HSO4(-) on the surface of the γ-AlOOH particles, and the hydrogen in HSO4(-) pointing towards the solvent lead to an unstable configuration of electric double layer (EDL). In the experiment, the gelation time sequence of γ-AlOOH sol obtained by adding metal ions changed when the ionic strength was equal to or greater than 0.198 mol kg(-1). The DFT calculations demonstrated that the adsorption energy of hydrated metal ions on the γ-AlOOH surface can actually make a difference in the sol-gel process.

  1. The effect of H2O gas on volatilities of planet-forming major elements. I - Experimental determination of thermodynamic properties of Ca-, Al-, and Si-hydroxide gas molecules and its application to the solar nebula

    NASA Technical Reports Server (NTRS)

    Hashimoto, Akihiko

    1992-01-01

    The vapor pressures of Ca(OH)2(g), Al(OH)3(g), and Si(OH)4(g) molecules in equilibrium with solid calcium-, aluminum, and silicon-oxides, respectively, were determined, and were used to derive the heats of formation and entropies of these species, which are expected to be abundant under the currently postulated physical conditions in the primordial solar nebula. These data, in conjunction with thermodynamic data from literature, were used to calculate the relative abundances of M, MO(x), and M(OH)n gas species and relative volatilities of Fe, Mg, Si, Ca, and Al for ranges of temperature, total pressure, and H/O abundance ratio corresponding to the plausible ranges of physical conditions in the solar nebula. The results are used to explain how Ca and Al could have evaporated from Ca,Al-rich inclusions in carbonaceous chondrites, while Si, Mg, and Fe condensed onto them during the preaccretion alteration of CAIs.

  2. A clear effect of charge compensation through Na+ co-doping on the luminescence spectra and decay kinetics of Nd3+-doped CaAl4O7

    NASA Astrophysics Data System (ADS)

    Puchalska, M.; Watras, A.

    2016-06-01

    We present a detailed analysis of luminescence behavior of singly Nd3+ doped and Nd3+, Na+ co-doped calcium aluminates powders: Ca1-xNdxAl4O7 and Ca1-2xNdxNaxAl4O7 (x=0.001-0.1). Relatively intense Nd3+ luminescence in IR region corresponding to typical 4F3/2→4IJ (J=9/2-13/2) transitions with maximum located at about 1079 nm was obtained in all samples on direct excitation into f-f levels. The effect of dopant concentration and charge compensation by co-doping with Na+ ions on morphology and optical properties were studied. The results show that both, the Nd3+ concentration and the alkali metal co-doping affected the optical properties but had no influence on the powders morphology. The studies of luminescence spectra (298 and 77 K) in a function of dopant concentration showed an increasing distortion of the local symmetry of Nd3+with raising activator content due to certain defects created in the crystal lattice. On the other hand Na+ addition led to significant narrowing of absorption and luminescence bands and also a reduction of the number of their components, showing smaller disturbance of Nd3+ ions local symmetries. Consequently, charge compensated by Na+ co-doping materials showed significantly enhanced Nd3+ luminescence. The decrease of emission intensity and luminescence lifetimes with increase of activator concentration was attributed mainly to phonon-assisted cross-relaxation processes between Nd3+ ions. Analysis with Inokuti-Hirayama model indicated dipole-dipole mechanism of ion-ion interaction. Na+ addition led to much smaller concentration quenching due to smaller clustering of dopant ions in CaAl4O7 lattice.

  3. [Effect of temperature on the structure of CaO-MgO-Al2O3-SiO2 nanocrystalline glass-ceramics studied by Raman spectroscopy].

    PubMed

    Li, Bao-Wei; Ouyang, Shun-Li; Zhang, Xue-Feng; Jia, Xiao-Lin; Deng, Lei-Bo; Liu, Fang

    2014-07-01

    In the present paper, nanocrystalline glass-ceramic of CaO-MgO-Al2O3-SiO2 system was produced by melting method. The CaO-MgO-Al2O3-SiO2 nanocrystalline glass-ceramic was measured by Raman spectroscopy in the temperature range from -190 to 310 degrees C in order to study the effect of temperature on the structure of this system nanocrystalline glass-ceramics. The results showed that different non-bridge oxygen bond silicon-oxygen tetrahedron structural unit changes are not consistent with rising temperature. Further analyses indicated that: the SiO4 tetrahedron with 2 non-bridged oxygen (Q2), the SiO4 tetrahedron with 3 non-bridged oxygen (Q(1)), which are situated at the edge of the 3-D SiO4 tetrahedrons network, and the SiO4 tetrahedron with 4 non-bridged oxygen (Q(0)), which is situated outside the 3-D network all suffered a significant influence by the temperature change, which has been expressed as: shifts towards the high wave-number, increased bond force constants, and shortened bond lengths. This paper studied the influence of temperature on CMAS system nanocrystalline glass-ceramics using variable temperature Raman technology. It provides experiment basis to the research on external environment influence on CMAS system nanocrystalline glass-ceramics materials in terms of structure and performance. In addition, the research provides experimental basis for controlling the expansion coefficient of nanocrystalline glass-ceramic of CaO-MgO-Al2O3-SiO2 system.

  4. Facile synthesis of Ca0.68Si9Al3(ON)16:Eu2+ microbelts mat with the enhanced fluorescence and mechanical performance

    NASA Astrophysics Data System (ADS)

    Zhao, Hailei; Cui, Bo; Wang, Hongzhi; Zhang, Qinghong; Li, Yaogang

    2016-01-01

    Yellow-emitting phosphor mat consisting of Ca0.68Si9Al3(ON)16:Eu2+ microbelts was prepared by electrospinning and subsequent nitridation. The as-prepared fiber precursor is smooth and uniform with diameter of 800 to 900 nm. After removing organic templates and nitridation, the morphology of the fiber is well retained and thus a smooth microbelts phosphor mat was obtained. X-ray diffraction and the photoluminescence (PL) spectra reveals that a relatively pure Ca0.68Si9Al3(ON)16 phase and the highest spectral intensity could be obtained at a relatively low temperature of 1500 °C and Eu2+ doping molar concentration of 0.1. The excitation spectra exhibits a broad band, ranging from 300 to 550 nm, which could be excited by blue LED chip at room temperature. The emission spectra of all exhibits a single broad band in the 400 to 700 nm region, with the maximum intensity always being at 580 nm. The Ca0.68Si9Al3(ON)16:Eu2+ microbelts phosphor mat has the bending strength about 4.5 MPa with a photoluminescence quantum yield as high as 65%. By employing it as yellow phosphor, a high-performance warm white LED could be fabricated with low correlated color temperature (2985 K), high-color-rendering index (Ra=86) and luminous efficacy of 129.5 lm W-1. Different color temperatures also could be tuned by employing microbelts phosphor mats with different thicknesses.

  5. Comparison of the electronic band structures of LiCaAlF6 and LiSrAlF6 ultraviolet laser host media from ab initio calculations

    NASA Astrophysics Data System (ADS)

    Viet Luong, Mui; Cadatal-Raduban, Marilou; Empizo, Melvin John F.; Arita, Ren; Minami, Yuki; Shimizu, Toshihiko; Sarukura, Nobuhiko; Azechi, Hiroshi; Pham, Minh Hong; Nguyen, Hung Dai; Kawazoe, Yoshiyuki

    2015-12-01

    We report the electronic structures and density of states (DOS) of perfect LiCAF and LiSAF crystals calculated from density functional theory (DFT) with local density approximation (LDA) using optimized lattice constants. DOS calculations reveal that the valence band is mainly derived from F 2p, thereby resulting to a very narrow valence band manifold. Meanwhile, the conduction band is mainly derived from Ca 4s or Sr 5s resulting to Sr having a broader band dispersion compared to Ca. Both fluoride compounds have indirect band gaps with LiCAF having a band gap of 8.02 eV and LiSAF a band gap of 7.92 eV. This is, to the best of our knowledge, the first report on the electronic structure of LiSAF calculated using DFT with LDA. Our results suggest that when doped with Ce3+, the shorter 5d-conduction band distance in Ce:LiSAF combined with the difficulty of growing high-purity crystals lead to the more pronounced excited state absorption (ESA) and solarization effect experimentally observed in Ce:LiSAF, limiting its potential as a laser material compared with Ce:LiCAF.

  6. Evidence for Extremely-High-Temperature Melting in the Solar Nebula from a CaAl4O7-bearing Spherule from Murchison

    NASA Astrophysics Data System (ADS)

    Simon, S. B.; Grossman, L.; Davis, A. M.; Beckett, J. R.; Chamberlin, L.

    1993-07-01

    We have recovered a unique refractory spherule (B6) from the Murchison C2 chondrite. Approximately 140 micrometers in diameter, it is concentrically zoned, with an outer rim sequence, from outermost to innermost, of aluminous diopside (10 micrometers thick), anorthite (3 micrometers) and melilite (3 micrometers). Inside the melilite layer is a 7-micrometer-thick, nearly pure (except for a single, diverging-inward spray of hibonite crystals) layer of spinel. Inward from this layer is a 22-micrometer-wide zone of hibonite (~5.5 wt% TiO2) + spinel, in which hibonite laths, 1-4 micrometers across and up to 10 micrometers wide, are predominantly radially oriented and enclosed in spinel. Inward from this zone, presumably at the core of the inclusion, are CaAl4O7, occurring as anhedral grains ~10 micrometers across, and minor perovskite. Some of the hibonite laths protrude into the CaAl4O7. The sequence of mineral assemblages from the spinel shell inward parallels that expected for fractional crystallization of a melt of the composition of B6. Based on this, the inclusion's spherical shape, and its texture (radially oriented hibonite laths, including a diverging-inward spray; laths enclosed in spinel and protruding into CaAl4O7), we conclude that the oxide phases in B6 crystallized from a liquid. The spinel layer indicates that at least some of the spinel was molten; from the bulk composition, calculated liquidus phase relations in the system Al2O3-MgO-CaO [1], and the amount of spinel contained in the layer, we infer a melting temperature >2000 degrees C. This is >500 degrees higher than the maximum temperature at which any condensed major phase is stable at 10-3 atm in a gas of solar composition, but we see no evidence of evaporation. First, the inclusion has a Group II REE pattern, rather than a Group III or an ultrarefractory pattern, which could reflect devolatilization. Second, although evaporation of molten (but not solid) Mg2SiO4 leads to Mg isotopic mass

  7. New insights into the application of the valence rules in Zintl phases-Crystal and electronic structures of Ba7Ga4P9, Ba7Ga4As9, Ba7Al4Sb9, Ba6CaAl4Sb9, and Ba6CaGa4Sb9

    NASA Astrophysics Data System (ADS)

    He, Hua; Stoyko, Stanislav; Bobev, Svilen

    2016-04-01

    Crystals of three new ternary pnictides-Ba7Al4Sb9, Ba7Ga4P9, and Ba7Ga4As9 have been prepared by reactions of the respective elements in molten Al or Pb fluxes. Single-crystal X-ray diffraction studies reveal that the three phases are isotypic, crystallizing in the orthorhombic Ba7Ga4Sb9-type structure (space group Pmmn, Pearson symbol oP40, Z=2), for which only the prototype is known. The structure is based on TrPn4 tetrahedra (Tr=Al, Ga; Pn=P, As, Sb), connected in an intricate scheme into 1D-ribbons. Long interchain Pn-Pn bonds (dP-P>3.0 Å; dAs-As>3.1 Å; dSb-Sb>3.3 Å) account for the realization of 2D-layers, separated by Ba2+ cations. Applying the classic valance rules to rationalize the bonding apparently fails, and Ba7Ga4Sb9 has long been known as a metallic Zintl phase. Earlier theoretical calculations, both empirical and ab-initio, suggest that the possible metallic properties originate from filled anti-bonding Pn-Pn states, and the special roles of the "cations" in this crystal structure. To experimentally probe this hypothesis, we sought to synthesize the ordered quaternary phases Ba6CaTr4Sb9 (Tr=Al, Ga). Single-crystal X-ray diffraction work confirms Ba6.145(3)Ca0.855Al4Sb9 and Ba6.235(3)Ca0.765Ga4Sb9, with Ca atoms preferably substituting Ba on one of the three available sites. The nuances of the five crystal structures are discussed, and the chemical bonding in Ba7Ga4As9 is interrogated by tight-binding linear muffin-tin orbital calculations.

  8. A double substitution induced Ca(Mg0.8, Al0.2)(Si1.8, Al0.2)O6:Eu(2+) phosphor for w-LEDs: synthesis, structure, and luminescence properties.

    PubMed

    Li, Yang; Liu, Wenjing; Wang, Xicheng; Zhu, Ge; Wang, Chuang; Wang, Yuhua

    2015-08-01

    A double substitution induced blue-emitting phosphor Ca(Mg0.8, Al0.2)(Si1.8, Al0.2)O6:Eu(2+) (CMAS:Eu(2+)) was successfully synthesized by a solid-state reaction process, and its structure and luminescence properties were investigated in detail. The crystal structure and chemical composition of the CMAS matrix were analyzed and determined based on Rietveld refinements and Energy Dispersive Spectroscopy (EDS). The composition-optimized CMAS:Eu(2+) exhibited a strong blue light, centered at 446 nm upon excitation at 365 nm with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.144, 0.113). Under 380 nm excitation, the PL emission intensity area of the optimized phosphor was found to be 46.95% of that of the commercial BaMgAl10O17:Eu(2+) (BAM:Eu(2+)) phosphor and the quantum efficiency of the phosphor is 41.32%. The temperature-dependent PL studies have been investigated which show the thermal stability of the CMAS:Eu(2+) phosphor compared with that of the CaMgSi2O6:Eu(2+) (CMS:Eu(2+)) phosphor. PMID:26115078

  9. A double substitution induced Ca(Mg0.8, Al0.2)(Si1.8, Al0.2)O6:Eu(2+) phosphor for w-LEDs: synthesis, structure, and luminescence properties.

    PubMed

    Li, Yang; Liu, Wenjing; Wang, Xicheng; Zhu, Ge; Wang, Chuang; Wang, Yuhua

    2015-08-01

    A double substitution induced blue-emitting phosphor Ca(Mg0.8, Al0.2)(Si1.8, Al0.2)O6:Eu(2+) (CMAS:Eu(2+)) was successfully synthesized by a solid-state reaction process, and its structure and luminescence properties were investigated in detail. The crystal structure and chemical composition of the CMAS matrix were analyzed and determined based on Rietveld refinements and Energy Dispersive Spectroscopy (EDS). The composition-optimized CMAS:Eu(2+) exhibited a strong blue light, centered at 446 nm upon excitation at 365 nm with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.144, 0.113). Under 380 nm excitation, the PL emission intensity area of the optimized phosphor was found to be 46.95% of that of the commercial BaMgAl10O17:Eu(2+) (BAM:Eu(2+)) phosphor and the quantum efficiency of the phosphor is 41.32%. The temperature-dependent PL studies have been investigated which show the thermal stability of the CMAS:Eu(2+) phosphor compared with that of the CaMgSi2O6:Eu(2+) (CMS:Eu(2+)) phosphor.

  10. Conductor-backed coplanar waveguide resonators of Y-Ba-Cu-O and Tl-Ba-Ca-Cu-O on LaAlO3

    NASA Technical Reports Server (NTRS)

    Miranda, F. A.; Bhasin, K. B.; Stan, M. A.; Kong, K. S.; Itoh, T.

    1992-01-01

    Conductor-backed coplanar waveguide (CBCPW) resonators operating at 10.8 GHz have been fabricated from Tl-Ba-Ca-O (TBCCO) and Y-Ba-Cu-O (YBCO) thin films on LaAlO3. The resonators consist of a coplanar waveguide (CPW) patterned on the superconducting film side of the LaAlO3 substrate with a gold ground plane coated on the opposite side. These resonators were tested in the temperature range from 14 to 106 K. At 77 K, the best of our TBCCO and YBCO resonators have an unloaded quality factor (Qo) 7 and 4 times, respectively, larger than that of a similar all-gold resonator. In this study, the Qo's of the TBCCO resonators were larger than those of their YBCO counterparts throughout the aforementioned temperature range.

  11. Observation of indium ion migration-induced resistive switching in Al/Mg0.5Ca0.5TiO3/ITO

    NASA Astrophysics Data System (ADS)

    Lin, Zong-Han; Wang, Yeong-Her

    2016-08-01

    Understanding switching mechanisms is very important for resistive random access memory (RRAM) applications. This letter reports an investigation of Al/Mg0.5Ca0.5TiO3 (MCTO)/ITO RRAM, which exhibits bipolar resistive switching behavior. The filaments that connect Al electrodes with indium tin oxide electrodes across the MCTO layer at a low-resistance state are identified. The filaments composed of In2O3 crystals are observed through energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, nanobeam diffraction, and comparisons of Joint Committee on Powder Diffraction Standards (JCPDS) cards. Finally, a switching mechanism resulting from an electrical field induced by In3+ ion migration is proposed. In3+ ion migration forms/ruptures the conductive filaments and sets/resets the RRAM device.

  12. Studies on charge transport in Al-doped La0.7Ca0.3Mn1-xAlxO3 manganites

    NASA Astrophysics Data System (ADS)

    Rathod, Jalshikhaba S.; Keshvani, M. J.; Solanki, P. S.; Pandya, D. D.; Kataria, Bharat; Shah, N. A.; Kuberkar, D. G.

    2015-12-01

    In this communication, we report the results of the studies on the effect of non-magnetic Al3+-doping on structure and properties of La0.7Ca0.3Mn1-xAlxO3 (LCMAO) manganites synthesized by conventional solid state reaction (SSR) route. The Rietveld refinement of the X-ray diffraction (XRD) data confirms the single phasic nature of the samples without any detectable impurities. All the samples exhibit metal to insulator transition (TP) which decrease with increase in Al3+ doping concentration while it increases with applied magnetic field. To understand the nature of charge transport in metallic and insulating regions of resistivity, various models and mechanisms have been used to fit the observed experimental data.

  13. Hybrid systems of AlInP microdisks and colloidal CdSe nanocrystals showing whispering-gallery modes at room temperature

    SciTech Connect

    Strelow, Christian; Weising, Simon; Bonatz, Dennis; Mews, Alf; Kipp, Tobias; Penttinen, Jussi-Pekka; Hakkarainen, Teemu V.; Schramm, Andreas

    2014-09-01

    We report on the realization of hybrid systems composed of passive optical microdisk resonators prepared from epitaxial layer systems and nanocrystal quantum emitters synthesized by colloidal chemistry. The AlInP disk material allows for the operation in the visible range, as probed by CdSe-based nanocrystals. Photoluminescence spectra at room temperature reveal sets of whispering-gallery modes consistent with finite-difference time-domain simulations. In the experiments, a special sample geometry renders it possible to detect resonant optical modes perpendicular to the disk plane.

  14. Exotic fluoride molecules in IRC +10216: Confirmation of AlF and searches for MgF and CaF

    NASA Technical Reports Server (NTRS)

    Ziurys, L. M.; Apponi, A. J.; Phillips, T. G.

    1994-01-01

    Three new rotational transitions of aluminum fluoride (AlF) at 0.8 and 1.2 mm have been observed. The J = 10-9, J = 8-7, and J = 7-6 lines of AlF at 230, 263, and 329 GHz, respectively, were seen toward IRC +10216 using the Caltech Submillimter Observatory (CSO). Combined with the earlier data obtained for this species at IRAM at 2 and 3 mm, these measurements confirm the presence of the metal halide in this carbon-rich circumstellar shell. Analysis of the CSO and IRAM data suggests that AlF arises from a source with a diameter of theta(sub s) approximately = 5-10 sec and hence is present chiefly in the inner envelope of IRC +10216. In this region, the molecule has a column density of (0.3-1.1) x 10(exp 15)/sq cm, which indicates a fractional abundance of at least approximately 10(exp -9), relative to H2. Searches for the metal fluoride species CaF and MgF have also been conducted toward IRC +10216, but with negative results. The column density upper limits for MgF and CaF are N(sub tot) less than (1-4) x 10(exp 14)/sq cm. Relative abundances of these metal fluoride molecules can be understood in terms of chemical thermodynamic equilibrium. The presence of AlF in IRC +10216 also indicates that large quantities of fluorine must be present in the inner stellar envelope, suggesting that this element may be produced not primarily in explosive nucleosynthesis but rather in helium shell flashes, as indicated also by HF spectroscopy of red giant stars.

  15. Hydrothermal origin of hexagonal CaAl2Si2O8 (dmisteinbergite) in a compact type A CAI from the Northwest Africa 2086 CV3 chondrite

    NASA Astrophysics Data System (ADS)

    Fintor, Krisztian; Park, Changkun; Nagy, Szabolcs; Pál-Molnár, Elemér; Krot, Alexander N.

    2014-05-01

    We report an occurrence of hexagonal CaAl2Si2O8 (dmisteinbergite) in a compact type A calcium-aluminum-rich inclusion (CAI) from the CV3 (Vigarano-like) carbonaceous chondrite Northwest Africa 2086. Dmisteinbergite occurs as approximately 10 μm long and few micrometer-thick lath-shaped crystal aggregates in altered parts of the CAI, and is associated with secondary nepheline, sodalite, Ti-poor Al-diopside, grossular, and Fe-rich spinel. Spinel is the only primary CAI mineral that retained its original O-isotope composition (Δ17O ~ -24‰); Δ17O values of melilite, perovskite, and Al,Ti-diopside range from -3 to -11‰, suggesting postcrystallization isotope exchange. Dmisteinbergite, anorthite, Ti-poor Al-diopside, and ferroan olivine have 16O-poor compositions (Δ17O ~ -3‰). We infer that dmisteinbergite, together with the other secondary minerals, formed by replacement of melilite as a result of fluid-assisted thermal metamorphism experienced by the CV chondrite parent asteroid. Based on the textural appearance of dmisteinbergite in NWA 2086 and petrographic observations of altered CAIs from the Allende meteorite, we suggest that dmisteinbergite is a common secondary mineral in CAIs from the oxidized Allende-like CV3 chondrites that has been previously misidentified as a secondary anorthite.

  16. Synthesis and properties of superconducting (Hg,Re)-Ba-Ca-Cu-O thick films on polycrystalline LaAlO 3 substrate obtained by screen-printing method

    NASA Astrophysics Data System (ADS)

    Przybylski, K.; Brylewski, T.; Bućko, M.; Prażuch, J.; Morawski, A.; Łada, T.

    2003-05-01

    A superconducting Hg 0.7Re 0.3Ba 2Ca 2Cu 3O 8+ δ thick film on a polycrystalline LaAlO 3 (LAO) substrate was obtained by a two-step method by screen-printing a Re 0.3Ba 2Ca 2Cu 3O x precursor coating on the substrate followed by high-pressure gas firing in Hg vapour. Morphological observations have revealed that the adherent to the ceramic substrate film exhibited highly porous microstructure composed of plate-like crystallites characterized by a superconducting transition temperature of about 110 K. The major phases identified were a high- Tc (Hg,Re)-1223 phase and a low- Tc (Hg,Re)-1212 phase. Non-superconducting secondary impurity phases were also identified. Energy dispersion X-ray spectroscopy analyses at the substrate/film boundary showed a thin continuous layer of BaLa 2O 4 compound, the presence of which confirmed chemical interaction between the LAO substrate and (Hg,Re)-Ba-Ca-Cu-O film.

  17. Synaptic conditions for auto-associative memory storage and pattern completion in Jensen et al.'s model of hippocampal area CA3.

    PubMed

    Cheu, Eng Yeow; Yu, Jiali; Tan, Chin Hiong; Tang, Huajin

    2012-12-01

    Jensen et al. (Learn Memory 3(2-3):243-256, 1996b) proposed an auto-associative memory model using an integrated short-term memory (STM) and long-term memory (LTM) spiking neural network. Their model requires that distinct pyramidal cells encoding different STM patterns are fired in different high-frequency gamma subcycles within each low-frequency theta oscillation. Auto-associative LTM is formed by modifying the recurrent synaptic efficacy between pyramidal cells. In order to store auto-associative LTM correctly, the recurrent synaptic efficacy must be bounded. The synaptic efficacy must be upper bounded to prevent re-firing of pyramidal cells in subsequent gamma subcycles. If cells encoding one memory item were to re-fire synchronously with other cells encoding another item in subsequent gamma subcycle, LTM stored via modifiable recurrent synapses would be corrupted. The synaptic efficacy must also be lower bounded so that memory pattern completion can be performed correctly. This paper uses the original model by Jensen et al. as the basis to illustrate the following points. Firstly, the importance of coordinated long-term memory (LTM) synaptic modification. Secondly, the use of a generic mathematical formulation (spiking response model) that can theoretically extend the results to other spiking network utilizing threshold-fire spiking neuron model. Thirdly, the interaction of long-term and short-term memory networks that possibly explains the asymmetric distribution of spike density in theta cycle through the merger of STM patterns with interaction of LTM network.

  18. Some thermodynamic properties of the Berman and Brown model for CaO-Al2O3-SiO2

    NASA Astrophysics Data System (ADS)

    Barron, Lawrence M.

    1986-12-01

    The BERMAN and BROWN (1984) excess free energy model (B&B) is extremely convenient to use in modelling multicomponent solutions. However, spinodal calculations reveal that their calibration of this model for CaO-Al2O3-SiO2 produces liquation tielines that do not appear to be in agreement with experimental work. In addition, their calibration contains some strongly negative excess entropy parameters and these permit a most unusual inverted liquation field to start at approximately >2115°C, wt% (SiO2, Al2O3, CaO) = (70, 16, 14). This inverted field expands rapidly to cover most of the ternary for T > 2300°C and continues to expand at all higher temperatures. The Berman and Brown calibration for this system carries these negative excess entropies of mixing because the solution model is very strongly asymmetric as a result of the use of normal oxide mole weights in modelling the configurational entropy of mixing. A suggestion is made for a fairly natural restriction on the relative sizes of empirical models for excess versus configurational entropy. Expressions are presented for the general consolute condition (all solution models) and for the second and third partials of the B&B Gx model.

  19. Effect of annealing under O2 and H2 on the piezoelectric parameters of the Ca12Al14O33 single crystals

    NASA Astrophysics Data System (ADS)

    Castel, Elias; Ik Shin, Tong; Fourcade, Sébastien; Decourt, Rodolphe; Maglione, Mario; García-Víllora, Encarnaçión; Shimamura, Kiyoshi

    2012-03-01

    Piezoelectric single-crystal ingots of Ca12Al14O33 were grown by Czochralski technique. Upon specific chemical reductions, this dielectric material can be turned into an oxygen solid electrolyte, a mixed conductor, or an electride. We followed the thermal evolution of the piezoelectric performances of as-grown samples and compared it with oxygen and hydrogen annealed ones. The structure of Ca12Al14O33 crystal was studied by powder x ray diffraction patterns, and the chemical processing efficiency was checked by optical transmittance measurements. The dielectric permittivity ɛ11 and piezoelectric coefficient d15 were found to be on the orders of 8-12 and 16-20 pC/N, respectively. This material exhibits good bulk shear wave coupling factor k14 about 0.34 and promising surface acoustic wave (SAW) velocities of 3500 m/s that render it suitable for SAW devices as a substrate. The piezoelectric response of crystals before and after annealing under H2 and O2 is maintained. The observed evolutions may be related to the conductivity of the material or the electrical transport properties, which are known to be sensitive to the oxygen and the hydrogen content.

  20. Photoemission-spectroscopy investigation of the chemical-pressure effect in Yb sub 1 minus x M x Al sub 2 ( M =Ca,Sc)

    SciTech Connect

    Vescovo, E.; Braicovich, L.; De Michelis, B.; Fasana, A. ); Eggenhoeffner, R. ); Iandelli, A.; Olcese, G.L.; Palenzona, A. )

    1991-05-15

    We present photoemission results with uv and with x rays from a family of pseudobinary compounds obtained by partial substitution of Yb, with Ca or Sc, in the reference compound YbAl{sub 2}. The substitution with Ca gives rise to a decompression and the one with Sc a compression of the lattice. Ultraviolet photoemission shows the perturbation of the electron states due to chemical substitution; Sc introduces a {ital d} character extending up to about 3 eV below the Fermi level. The weights of the Yb{sup 3+} and Yb{sup 2+} multiplets given by x-ray photoemission are compared with the results from x-ray absorption; the two spectroscopies agree in YbAl{sub 2} while the relative weights Yb{sup 3+} versus Yb{sup 2+} from x-ray photoemission are definitely below the x-ray-absorption values in the compounds heavily substituted with Sc; this is interpreted as a photoemission final-state effect connected with the {ital d} character introduced by the substitution.

  1. Preparation and characterization of Tl sub 2 Ba sub 2 CaCu sub 2 O sub 8 films on (100) LaAlO sub 3

    SciTech Connect

    Holstein, W.L.; Parisi, L.A.; Kountz, D.J.; Wilker, C.; Matthews, A.L. ); Arendt, P.N. ); Taber, R.C. )

    1991-03-01

    A two-step process for the fabrication of 0.12-1.20 {mu}m-thick Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8} films on (100) LaAlO{sub 3} has been developed. The process involves the deposition of a BaCaCuO precursor film at low temperature by rf magnetron sputtering, followed by annealing in the presence of Tl{sub 2}O vapor to convert the precursor film into Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8}. Over a distance of 4 cm, film composition was Tl:Ba:Ca:Cu = 2.05 {plus minus} 0.09:2.05 {plus minus} 0.06:1.0 {plus minus} 0.3:1.94 {plus minus} 0.6 and thickness was uniform to within 6%. The films contain only trace quantities of secondary phases and are epitaxially oriented, with the c-axis of Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8} perpendicular to the surface and the two a-axes aligned with the pseudo-cubic a-axes of the underlying LaAlO{sub 3} substrate. Films had a T{sub c} for zero dc resistivity of 106.5 {plus minus} 0.5 K,a transport critical current density for continuous current of 2.9 {times} 10{sup 6} A-cm{sup {minus}2} at 77 K, and a sharp ({lt}0.3{degrees} C) ac inductance transition with an onset temperature of 105 {plus minus} 2 K. Surface resistance at 20 GHz less than 2 m{Omega}, about 10X lower than Cu, was routinely achieved for temperatures below 90 K and, for the best films, at temperatures up to 100 K. Surface resistance at about 10 GHz on one film was 0.067 m{Omega} at 4.2 K, 0.36 m{Omega} at 77 K, and 0.74 m{Omega} at 90 K. Films have been reproducibly fabricated on substrates up to 2.54 cm square.

  2. [Effects of adsorbents on partitioning of Cd and Pb in MSW incineration].

    PubMed

    Wu, Rong; Li, Qing-Hai; Meng, Ai-Hong; Zhang, Yan-Guo; Chen, Yong

    2009-07-15

    An incineration experiment using simulated municipal solid waste (MSW) in the tubular furnace was performed to study the effects of SiO2, Al2o3 and CaO on the partitioning of Cd and Pb under different operating conditions which included adsorbents percentage, furnace temperature and residence time. The results indicated that the increasing of SiO2, AL2O3, CaO concentration were favorable for Cd to partition in the bottom ash. And for Pb, SiO2 and Al2O3 had the same effects. However, the condition with CaO showed an opposite tendency of increasing Pb distribution in fly ash. While all of these adsorbents increasing, the effects were also enhanced. When the temperature of the tubular furnace was 850 degrees C, the adsorption efficiencies of these adsorbents for Cd were in the sequence of CaO > Al, O3 > SiO2, and for Pb, Al2O3 > SiO2 > CaO. In addition,with increasing of tubular furnace temperature and residence time, there would be more Cd and Pb compounds moving to the fly ash.

  3. Evaluation of thermochemical data on Fe-Mg olivine, orthopyroxene, spinel and Ca-Fe-Mg-Al garnet

    SciTech Connect

    Chatterjee, N.

    1987-09-01

    Thermochemical data on Fe-Mg olivine, orthopyroxene, spinel and Ca-Fe-Mg garnet have been tested and reevaluated in reproducing experimental equilibrium data. All data (except of spinel) adjusted in this process lie within the error limits of original calorimetric experiments. For spinel, an enthalpy of -2307.2 kJmol and an entropy of 81.5 Jmol-K has been recommended. Recommended interaction parameters for the spinel-hercynite and forsterite-fayalite solutions are as follows: Spinel: W/sub (spinel-hercynite)/= 9124.0 Jmol. W/sub (hercynite-spinel)/ = 0.0 Jmol. Olivine: W = 4500.0 Jmol for 1 cation. Excess entropies (on 1 cation basis) necessary to reproduce phase equilibria for the pyrope-almandine and almandine-grossular solutions are as follows: Mg-Fe garnet: Wsub(pyrope-almandine) = 11.760 - 0.0016T Jmol-K. Wsub(almandine-pyrope) = -10.146 + 0.0037T Jmol-K. Fe-Ca garnet: W/sup s/ = -16.07 + 0.0126T Jmol-K.

  4. Effects of the mixing ratio of the CaAl12O19:mn and Zn2SiO4:mn color-conversion layer on the color tunable emissions of white organic light-emitting devices.

    PubMed

    Jeong, H S; Kim, S H; Bang, H S; Choo, D C; Kim, T W; Hwang, D H; Kwon, M S; Chu, C

    2012-02-01

    The optical properties of white organic light-emitting devices (WOLEDs) fabricated utilizing a CaAl12O19:Mn and Zn2SiO4:Mn phosphor layer were investigated. X-ray diffraction patterns for CaAl12O19:Mn and Zn2SiO4:Mn phosphors showed that Mn ions in the CaAl12O19:Mn phosphors were completely substituted into Ca ions and that Mn ions in the Zn2SiO4:Mn phosphors were completely substituted into Zn ions. Field emission scanning electron microscopy images showed that the size of the CaAl12O19:Mn phosphor was approximately between 0.1 and 3 microm, and that the size of the Zn2SiO4:Mn phosphor was smaller than 7 microm. The color coordinates of the electroluminescence spectra for WOLEDs with phosphor thicknesses of 0.25 and 0.35 mm shifted to the white emission side because the generated blue light from the blue OLEDs combined with the red and green lights was converted by the CaAl12O19:Mn and the Zn2SiO4:Mn phosphor down-conversion layers. PMID:22630022

  5. Effects of the mixing ratio of the CaAl12O19:mn and Zn2SiO4:mn color-conversion layer on the color tunable emissions of white organic light-emitting devices.

    PubMed

    Jeong, H S; Kim, S H; Bang, H S; Choo, D C; Kim, T W; Hwang, D H; Kwon, M S; Chu, C

    2012-02-01

    The optical properties of white organic light-emitting devices (WOLEDs) fabricated utilizing a CaAl12O19:Mn and Zn2SiO4:Mn phosphor layer were investigated. X-ray diffraction patterns for CaAl12O19:Mn and Zn2SiO4:Mn phosphors showed that Mn ions in the CaAl12O19:Mn phosphors were completely substituted into Ca ions and that Mn ions in the Zn2SiO4:Mn phosphors were completely substituted into Zn ions. Field emission scanning electron microscopy images showed that the size of the CaAl12O19:Mn phosphor was approximately between 0.1 and 3 microm, and that the size of the Zn2SiO4:Mn phosphor was smaller than 7 microm. The color coordinates of the electroluminescence spectra for WOLEDs with phosphor thicknesses of 0.25 and 0.35 mm shifted to the white emission side because the generated blue light from the blue OLEDs combined with the red and green lights was converted by the CaAl12O19:Mn and the Zn2SiO4:Mn phosphor down-conversion layers.

  6. Structure and Crystallization Kinetics of Glassy CaO-Al2O3-SiO2-CaF2-Na2O Mold Fluxes with Varying Basicity

    NASA Astrophysics Data System (ADS)

    Li, Jiangling; Yan, Baijun; Shu, Qifeng; Chou, Kuochih

    2015-12-01

    The structure and the crystallization kinetics of CaO-Al2O3-SiO2-CaF2-Na2O mold fluxes with varying basicities were investigated by solid-state 29Si nuclear magnetic resonance with magic angular spinning (MAS-NMR) and differential thermal analysis (DTA) technique, respectively. 29Si MAS-NMR study indicated that the increase of basicity decreased the degree of polymerization of mold fluxes. With the increasing basicity, Q 0, Q 2, and Q 3 gradually decreased, while Q 1 gradually increased, and the overall degree of polymerization was reduced. Crystallization analysis showed the cuspidine first crystallized from glass, and wollastonite crystal crystallized at elevated temperature for the samples with basicity (defined as CaO/SiO2 mass ratio) values of 0.9 and 1.0, respectively. Only cuspidine was found to crystallize from glass for the samples with basicity values of 1.1 and 1.2, indicating that the crystallization of wollastonite was suppressed with the increase of basicity. Crystallization kinetics analysis by DTA and field emission scanning electron microscopy equipped with energy dispersive spectroscopy investigation showed that growth mechanism of cuspidine is mainly of the diffusion-controlled three-dimensional growth with the increasing number of nuclei during heating. Activation energies for growth of cuspidine decreased with the increasing basicity of mold flux, which indicated that the crystallization ability was enhanced with the increase of basicity. The relationship between structure and crystallization of mold fluxes was established.

  7. High pressure study of low compressibility tetracalcium aluminum carbonate hydrates 3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}CaCO{sub 3}{center_dot}11H{sub 2}O

    SciTech Connect

    Moon, Juhyuk; Oh, Jae Eun; Balonis, Magdalena; Glasser, Fredrik P.; Clark, Simon M.; Monteiro, Paulo J.M.

    2012-01-15

    Synchrotron X-ray diffraction data was collected from a sample of monocarboaluminate 3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}CaCO{sub 3}{center_dot}11H{sub 2}O from ambient pressure to 4.3 GPa. The refined crystal structure at ambient pressure is triclinic with parameters a = 5.77(2) A, b = 8.47(5) A, c = 9.93(4) A, {alpha} = 64.6(2) Degree-Sign , {beta} = 82.8(3) Degree-Sign , {gamma} = 81.4(4) Degree-Sign , and space group of P1 or P1{sup Macron }. It showed some degree of perfectly reversible pressure-induced dehydration with a non-hygroscopic pressure-transmitting medium. However the dehydration effect does not critically affect a bulk modulus due to its strong framework. The isothermal bulk modulus of monocarboaluminate was found to be 53(5) GPa and 54(4) GPa with 3rd order and 2nd order Birch-Murnaghan Equation of state, respectively. That value is higher than for any other reported AFm or AFt phase. The pressure-volume behavior of the monocarboaluminate was compared with that of previous studied hemicarboaluminate.

  8. Ca-Al-rich inclusions from the Ningqiang meteorite: continuous assemblages of nebular condensates and genetic link to Type B inclusions

    NASA Astrophysics Data System (ADS)

    Lin, Y.; Kimura, M.

    2003-06-01

    The petrography and mineral chemistry of 110 Ca-, Al-rich inclusions (CAIs) and 9 Ca- and/or Al-rich amoeboid olivine aggregates (AOAs) from the Ningqiang carbonaceous chondrite are reported. These CAIs are referred to as hibonite-bearing and hibonite-free melilite-spinel-rich (Type A), and spinel-pyroxene inclusions. Melilite is more gehlenitic in the hibonite-bearing Type As than in the other two types, and all of them vary within a range of Åk 0-30. Modal compositions of the three types of CAIs overlap with each other, and make up a continuum with wide ranges of melilite: spinel: diopside. The diopside occurs as rims on the CAIs or their individual concentric objects. The 9 AOAs contain spinel ± diopside ± anorthite in the centers of the aggregates; the spinel grains rimmed by diopside in the centers are similar to the spinel-pyroxene inclusions. Bulk compositions of these CAIs vary along the condensation trajectory, with the hibonite-bearing Type As plotting at the beginning followed by hibonite-free Type As then by spinel-pyroxene inclusions as temperature decreases. Bulk compositions of the AOAs are close to the lowest temperature condensation trajectory. Except for a few with compact textures, most of the Type As and spinel-pyroxene inclusions are fluffy aggregates, probably pristine vapor-solid condensates of the nebula. The bulk compositions of the Type As appear to overlap with the range of most melilite-Ti-Al-clinopyroxene-rich (Type B) inclusions. Hence, crystallization of liquids produced by melting the Type As can form Type B inclusions, without significant evaporative loss of MgO or SiO 2. A few Type Bs have bulk compositions deviating from the range of their proposed precursors, and may have suffered significant evaporation, as suggested in previous studies.

  9. Symmetry-dependent interfacial reconstruction to compensate polar discontinuity at perovskite oxide interfaces (LaAlO{sub 3}/SrTiO{sub 3} and LaAlO{sub 3}/CaTiO{sub 3})

    SciTech Connect

    Lee, Joohwi; Moon, Seon Young; Kim, Jin-Sang; Choi, Jung-Hae E-mail: almacore@kist.re.kr; Choi, Jong Kwon; Park, Jaehong; Hwang, Cheol Seong; Baek, Seung-Hyub; Chang, Hye Jung E-mail: almacore@kist.re.kr

    2015-02-16

    We report the crystal symmetry-dependency of the interfacial reconstruction to relieve the polar discontinuity at the complex oxide heterointerfaces. We chose LaAlO{sub 3}/SrTiO{sub 3} and LaAlO{sub 3}/CaTiO{sub 3} interfaces as model systems, where the neutral TiO{sub 2} and the positive LaO{sup +} layers form the polar discontinuity at the interface with TiO{sub 2}-terminated (001) cubic SrTiO{sub 3} and orthorhombic CaTiO{sub 3}. Using scanning transmission electron microscopy, we observed that the interlayer distance abnormally increased at the interface. We performed the first-principles calculations to understand the detailed atomic displacement at the interfaces having no oxygen vacancy and intermixing. Our results show that cations were reconstructed in different ways depending on the crystal symmetry through the octahedral tilts and atomic displacements to compensate the polar discontinuity at the interfaces. Our results imply that the interfacial reconstructions have to be considered along with the ionic compensation (intermixing) and electronic compensation (two dimensional electron gas) to fully understand the interfacial phenomena.

  10. Formation Mechanism of CaO-SiO2-Al2O3-(MgO) Inclusions in Si-Mn-Killed Steel with Limited Aluminum Content During the Low Basicity Slag Refining

    NASA Astrophysics Data System (ADS)

    Wang, Kunpeng; Jiang, Min; Wang, Xinhua; Wang, Ying; Zhao, Haoqian; Cao, Zhanmin

    2016-02-01

    Pilot trails were carried out to study the formation mechanism of CaO-SiO2-Al2O3-(MgO) inclusions in tire cord steel. 48 samples were taken from 8 heats of liquid steel during secondary refining, which were subsequently examined by an automatic scanning electron microscope with energy dispersive spectrometer (SEM-EDS). Characteristics of thousands of oxide inclusions at different refining stages were obtained, including their compositions, sizes, morphologies, etc. Based on the obtained information of inclusions, details during formation of CaO-SiO2-Al2O3-(MgO) inclusions were revealed and a new mechanism was proposed, including their origin, formation, and evolution during the refining process. It was found that CaO-SiO2-Al2O3-(MgO) inclusions were initially originated from the CaO-SiO2-MnO-(MgO) inclusions, which were formed during BOF tapping by the coalescence between MnO-SiO2 deoxidation products and the emulsified slag particles because of violent flow of steel. This can be well confirmed by the evaluation of the formation thermodynamics of CaO-SiO2-MnO-(MgO) inclusions, which was proved very difficult to be produced by intrinsic reactions inside liquid steel. Because of chemical reactions between CaO-SiO2-MnO-(MgO) inclusions and molten steel, they were mainly changed into CaO-SiO2-MnO-Al2O3-(MgO) and partially into CaO-SiO2-Al2O3-(MgO), which may be detrimental to the cold drawing ability of coils. Based on this finding, improvements were made in industrial production during BOF tapping and secondary refining. The results indicated that such (CaO-SiO2)-based inclusions existed in conventional process were effectively decreased after the improvements.

  11. Ultrasensitive photoelectrochemical immunoassay for CA19-9 detection based on CdSe@ZnS quantum dots sensitized TiO2NWs/Au hybrid structure amplified by quenching effect of Ab2@V(2+) conjugates.

    PubMed

    Zhu, Hua; Fan, Gao-Chao; Abdel-Halim, E S; Zhang, Jian-Rong; Zhu, Jun-Jie

    2016-03-15

    A novel, enhanced photoelectrochemical immunoassay was established for sensitive and specific detection of carbohydrate antigen 19-9 (CA19-9, Ag). In this protocol, TiO2 nanowires (TiO2NWs) were first decorated with Au nanoparticles to form TiO2NWs/Au hybrid structure, and then coated with CdSe@ZnS quantum dots (QDs) via the layer-by-layer method, producing TiO2NWs/Au/CdSe@ZnS sensitized structure, which was employed as the photoelectrochemical matrix to immobilize capture CA19-9 antibodies (Ab1); whereas, bipyridinium (V(2+)) molecules were labeled on signal CA19-9 antibodies (Ab2) to form Ab2@V(2+) conjugates, which were used as signal amplification elements. The TiO2NWs/Au/CdSe@ZnS sensitized structure could adequately absorb light energy and dramatically depress electron-hole recombination, resulting in evidently enhanced photocurrent intensity of the immunosensing electrode. While target Ag were detected, the Ab2@V(2+) conjugates could significantly decrease the photocurrent detection signal because of strong electron-withdrawing property of V(2+) coupled with evident steric hindrance of Ab2. Thanks to synergy effect of TiO2NWs/Au/CdSe@ZnS sensitized structure and quenching effect of Ab2@V(2+) conjugates, the well-established photoelectrochemical immunoassay exhibited a low detection limit of 0.0039 U/mL with a wide linear range from 0.01 U/mL to 200 U/mL for target Ag detection. This proposed photoelectrochemical protocol also showed good reproducibility, specificity and stability, and might be applied to detect other important biomarkers. PMID:26433066

  12. Ultrasensitive photoelectrochemical immunoassay for CA19-9 detection based on CdSe@ZnS quantum dots sensitized TiO2NWs/Au hybrid structure amplified by quenching effect of Ab2@V(2+) conjugates.

    PubMed

    Zhu, Hua; Fan, Gao-Chao; Abdel-Halim, E S; Zhang, Jian-Rong; Zhu, Jun-Jie

    2016-03-15

    A novel, enhanced photoelectrochemical immunoassay was established for sensitive and specific detection of carbohydrate antigen 19-9 (CA19-9, Ag). In this protocol, TiO2 nanowires (TiO2NWs) were first decorated with Au nanoparticles to form TiO2NWs/Au hybrid structure, and then coated with CdSe@ZnS quantum dots (QDs) via the layer-by-layer method, producing TiO2NWs/Au/CdSe@ZnS sensitized structure, which was employed as the photoelectrochemical matrix to immobilize capture CA19-9 antibodies (Ab1); whereas, bipyridinium (V(2+)) molecules were labeled on signal CA19-9 antibodies (Ab2) to form Ab2@V(2+) conjugates, which were used as signal amplification elements. The TiO2NWs/Au/CdSe@ZnS sensitized structure could adequately absorb light energy and dramatically depress electron-hole recombination, resulting in evidently enhanced photocurrent intensity of the immunosensing electrode. While target Ag were detected, the Ab2@V(2+) conjugates could significantly decrease the photocurrent detection signal because of strong electron-withdrawing property of V(2+) coupled with evident steric hindrance of Ab2. Thanks to synergy effect of TiO2NWs/Au/CdSe@ZnS sensitized structure and quenching effect of Ab2@V(2+) conjugates, the well-established photoelectrochemical immunoassay exhibited a low detection limit of 0.0039 U/mL with a wide linear range from 0.01 U/mL to 200 U/mL for target Ag detection. This proposed photoelectrochemical protocol also showed good reproducibility, specificity and stability, and might be applied to detect other important biomarkers.

  13. Cr{sup 6+}-containing phases in the system CaO-Al{sub 2}O{sub 3}-CrO{sub 4}{sup 2-}-H{sub 2}O at 23 Degree-Sign C

    SciTech Connect

    Poellmann, Herbert

    2012-01-15

    Synthesis and investigation of lamellar calcium aluminium hydroxy salts was performed to study the incorporation of chromate ions in the interlayer of lamellar calcium aluminium hydroxy salts. Different AFm-phases (calcium aluminate hydrate with alumina, ferric oxide, mono-anion phase) containing chromate were synthesized. These AFm-phases belong to the group of layered double hydroxides (LDHs). 3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}CaCrO{sub 4}{center_dot}nH{sub 2}O and C{sub 3}A{center_dot}1/2Ca(OH){sub 2}{center_dot}1/2CaCrO{sub 4}{center_dot}12H{sub 2}O were obtained as pure phases and their different distinct interlayer water contents and properties determined. Solid solution of chromate-containing phases and tetracalcium-aluminate-hydrate (TCAH) were studied. The uptake of chromate into TCAH from solutions was proven. Chromate contents in solution decrease to <0.2 mg/l. - Graphical abstract: Chromate can be incorporated in LDH-phases with compositions like: 3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}1/2CaCrO{sub 4}{center_dot}1/2Ca(OH){sub 2}{center_dot}nH{sub 2}O, 3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}CaCrO{sub 4}{center_dot}nH{sub 2}O, 3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}1/6CaCrO{sub 4}.{center_dot}5/6Ca(OH){sub 2}{center_dot}nH{sub 2}O, 3CaO{center_dot}Al{sub 2}O{sub 3}(0-x)CaCrO{sub 4}(1-x) Ca(OH){sub 2}{center_dot}12H{sub 2}O, (0CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}CaCrO{sub 4}{center_dot}nH{sub 2}O and C{sub 3}A{center_dot}1/2 Ca(OH){sub 2}{center_dot}1/2 CaCrO{sub 4}{center_dot}12 H{sub 2}O are given. Black-Right-Pointing-Pointer Different hydrates of Ca-Al-hydroxysalts (LDH) with chromate-anions synthesized and characterized. Black-Right-Pointing-Pointer Interlayer exchange reaction of 2OH{sup -} and CrO{sub 4}{sup 2-} investigated. Black-Right-Pointing-Pointer Thermal dehydration and change of lattice parameters are given

  14. Fluoride phosphors in the system (CaF/sub 2/-AlF/sub 3/)-Mn/sup 2 +/ with long afterglow

    SciTech Connect

    Shamshurin, A.V.; Voevudskaya, S.V.; Zhikhareva, E.A.; Efryushina, N.P.; Magunov, I.R.

    1987-03-01

    By codeposition from solutions, crystal phosphors are obtained in the system (CaF/sub 2/-AlF/sub 3/)-Mn/sup 2 +/. The authors have studied the intensity of x-ray luminescence and the brightness of cathode luminescence versus the concentration of Mn and also on the time and temperature of roasting. The kinetics of decay of the luminescence are investigated. Composition-property diagrams are constructed. As the AlF/sub 3/ concentration is increased, the luminescence band of Mn/sup 2 +/ (transition /sup 4/T/sub lg/(/sup 4/G) ..-->.. /sup 6/A/sub lg/(/sup 6/S)) gradually shifts into the long-wave region, the time of afterglow increases, and the decay of its intensity in the end acquires a clearly marked hyperbolic character. All this means that addition of AlF/sub 3/ probably increases the force of the field of the ligands and causes new radiation-induced defects in the specimens.

  15. Analysis of the Fe-Ce-O-C- M phase diagrams ( M = Ca, Mg, Al, Si) by constructing a component-solubility surface

    NASA Astrophysics Data System (ADS)

    Mikhailov, G. G.; Makrovets, L. A.; Smirnov, L. A.; Dresvyankina, L. E.

    2016-06-01

    Analysis of the ternary phase diagrams of Ce2O3- and CeO2-containing oxide systems allowed us to find the oxide compounds that form during steel deoxidizing with cerium and with cerium together with aluminum, calcium, magnesium, or silicon. The temperature dependences of the equilibrium constants of formation of Ce2O3 oxides and Ce2O3 · Al2O3, Ce2O3 · 11Al2O3, Ce2O3 · 2SiO2, 7Ce2O3 · 9SiO2 and Ce2O3 · SiO2 compounds are found. Surfaces for the component solubility in metallic melts Fe-Al-Ce-O-C, Fe- Ca-Ce-O-C, Fe-Mg-Ce-O-C, and Fe-Si-Ce-O-C are constructed. Nonmetallic inclusions that form in the course of experimental melts of St20 steel after its deoxidizing with silicocalcium and rare-earth metal (REM)-containing master alloys in a ladle furnace after degassing are studied. Phase inhomogeneity of the inclusions is found. As a rule, they consist of phases classified into the following three groups: oxide-sulfide, sulfide-oxide, and multiphase oxide-sulfide melt. Calcium aluminates are found to be components of complex sulfide-oxide noncorrosive inclusions.

  16. Novel acid-labile subunit ( IGFALS ) mutation p.T145K (c.434C>A) in a patient with ALS deficiency, normal stature and immunological dysfunction.

    PubMed

    Schreiner, Felix; Schoenberger, Stefan; Koester, Bernhard; Domené, Horacio M; Woelfle, Joachim

    2013-01-01

    We report a novel missense mutation p.T145K in the insulin-like growth factor (IGF) acid-labile subunit (IGFALS) gene identified in a Turkish patient with normal growth, transient pancytopenic episodes and signs of immunological dysfunction. Because of recurrent cutaneous mycoses and absence of pubertal development until the age of 14.75 years we determined several endocrine parameters in order to rule out autoimmune-polyendocrine syndromes. Despite a normal height between the 25th and 50th percentile we found severely decreased IGF-1 and undetectably low IGFBP-3 levels. Laboratory signs of immunological dysfunction included reduced total lymphocyte count with diminished B and T helper cell fractions, decreased serum concentrations of IgM and IgG subclass 4, and elevated antinuclear antibody and anti-dsDNA titers as well as persistently high interleukin-2-receptor levels. Further endocrine work-up revealed elevated fasting insulin and undetectably low ALS serum levels, leading to the diagnosis of ALS deficiency. Sequencing of the coding region of the IGFALS gene showed a novel homozygous missense mutation (c.434C>A; p.T145K). Since immunological abnormalities have not been reported in more than 20 ALS-deficient patients so far and our patient was born to consanguineous parents, a second autosomal recessive defect is likely to underlie the immunological phenotype, although a causative role of IGFALS p.T145K cannot be entirely ruled out. PMID:24296365

  17. NOx uptake on alkaline earth oxides (BaO, MgO, CaO and SrO) supported on γ-Al2O3

    SciTech Connect

    Verrier, Christelle LM; Kwak, Ja Hun; Kim, Do Heui; Peden, Charles HF; Szanyi, Janos

    2008-07-15

    NOx uptake experiments were performed on a series of alkaline earth oxide (AEO) (MgO, CaO, SrO, BaO) on γ-alumina materials. Temperature Programmed Desorption (TPD) conducted on He flow revealed the presence of two kinds of nitrate species: i.e. bulk and surface nitrates. The ratio of these two types of nitrate species strongly depends on the nature of the alkaline earth oxide. The amount of bulk nitrate species increases with the basicity of the alkaline earth oxide. This conclusion was supported by the results of infrared and 15N solid state NMR studies of NO2 adsorption. Due to the low melting point of the precursor used for the preparation of MgO/Al2O3 material (Mg(NO3)2), a significant amount of Mg was lost during sample activation (high temperature annealing) resulting in a material with properties were very similar to that of the γ-Al2O3 support. The effect of water on the NOx species formed in the exposure of the AEO-s to NO2 was also investigated. In agreement with our previous findings for the BaO/γ-Al2O3 system, an increase of the bulk nitrate species and the simultaneous decrease of the surface nitrate phase were observed for all of these materials.

  18. Synthesis of layered double hydroxides containing Mg2+, Zn2+, Ca2+ and Al3+ layer cations by co-precipitation methods-A review

    NASA Astrophysics Data System (ADS)

    Theiss, Frederick L.; Ayoko, Godwin A.; Frost, Ray L.

    2016-10-01

    Co-precipitation is a common method for the preparation of layered double hydroxides (LDHs) and related materials. This review article is aimed at providing newcomers to the field with some examples of the types of co-precipitation reactions that have been reported previously and to briefly investigate some of the properties of the products of these reactions. Due to the sheer volume of literature on the subject, the authors have had to limit this article to the synthesis of Mg/Al, Zn/Al and Ca/Al LDHs by co-precipitation and directly related methods. LDHs have been synthesised from various reagents including metal salts, oxides and hydroxides. Co-precipitation is also useful for the direct synthesis of LDHs with a wide range of interlayer anions and various bases have been successfully employed to prepare LDHs. Examples of other synthesis techniques including the urea method, hydrothermal synthesis and various mechanochemical methods that are undoubtedly related to co-precipitation have also been included in this review. The effect of post synthesis hydrothermal has also been summarised.

  19. Melts in the Deep Earth: Calculating the Densities of CaO-FeO-MgO-Al2O3-SiO2 Liquids

    NASA Astrophysics Data System (ADS)

    Thomas, C.; Guo, X.; Agee, C. B.; Asimow, P. D.; Lange, R. A.

    2012-12-01

    We present new equation of state (EOS) measurements for hedenbergite (Hd, CaFeSi2O6) and forsterite (Fo, Mg2SiO4) liquids. These liquid EOS add to the basis set in the CaO-FeO-MgO-Al2O3-SiO2 (CMASF) oxide space at elevated temperatures and pressures; other liquids include: enstatite (En, MgSiO3), anorthite (An, CaAl2Si2O8), diopside (Di, CaMgSi2O6), and fayalite (Fa, Fe2SiO4). The Hd EOS measurement was a multi-technique collaboration using 1-atm double-bob Archimedean, ultrasonic, sink/float, and shock wave techniques. Un-weighted linear fitting of the shock data in shock velocity (US)-particle velocity (up) space defines a pre-heated (1400 °C) Hugoniot US = 2.628(0.024) + 1.54(0.01)up km/s. The slope corresponds to a K' of 5.16(0.04), consistent with piston-cylinder and multi-anvil sink/float experiments. The intercept is fixed at the ultrasonic sound speed (Co) since the unconstrained intercept is within the stated error. This behavior demonstrates consistency across methods and that the liquid is relaxed during shock compression. Shock compression of pre-heated (2000°C) single crystal Fo gives an un-weighted linear Hugoniot of US = 2.674(0.188) + 1.64(0.06)up km/s. The unconstrained Co falls below estimates based on extrapolation in both temperature and composition from two published partial molar sound speed models, 3.195m/s [1] and 3.126 m/s [2]. The shock-derived Co indicates that dC/dT is negative for Fo liquid, contrary to the positive [1] and zero [2] temperature dependences derived over relatively narrow temperature intervals. CMASF liquid isentropes were calculated using five end-members (En, Fo, Fa, An, Di). For modeling crystallization of a fictive magma ocean, we examined two liquids: peridotite [3] (P=.33En+.56Fo+.07Fa+.03An+.007Di) and simplified chondrite [4] (Ch=.62En+.24Fo+.08Fa+.04An+.02Di). Each end-member is defined by a 3rd or 4th order Birch-Murnaghan isentrope, Mie-Grüneisen thermal pressure and a constant heat capacity. The volumes are

  20. The CNGRC-GG-D(KLAKLAK)2 peptide induces a caspase-independent, Ca2+-dependent death in human leukemic myeloid cells by targeting surface aminopeptidase N/CD13.

    PubMed

    Bouchet, Sandrine; Tang, Ruoping; Fava, Fanny; Legrand, Ollivier; Bauvois, Brigitte

    2016-04-12

    The CD13 antigen's binding site for the Asn-Gly-Arg (NGR) motif enables NGR-containing chemotherapeutic drugs to be delivered to CD13-positive tumours. Human CD13-positive acute myeloid leukemia (AML) cells proliferate abnormally and escape death. Here, we show that the CNGRC-GG-D(KLAKLAK)2 peptide induces death in AML cell lines (U937, THP-1, NB4, HL-60) and primary blood cells from AML patients. Cell death was characterized as a caspase-independent mechanism, without DNA fragmentation, but phosphatidylserine externalization and membrane disruption. Our results demonstrate in U937 cells that (i) the NGR-peptide triggers the loss of mitochondrial potential(ΔΨm) and generates superoxide anion (O2-), (ii) N-acetyl-L-cysteine (NAC) and extra/intracellular Ca2+ chelators (BAPTA) prevent both O2- production and cell death, (iii) the Ca2+-channel blocker nifedipine prevents cell death (indicating that Ca2+ influx is the initial death trigger), and (iv) BAPTA, but not NAC, prevents ΔΨm loss (suggesting O2- is a mitochondrial downstream effector). AML cell lines and primary blasts responding to the lethal action of NGR-peptide express promatrix metalloproteinase-12 (proMMP-12) and its substrate progranulin (an 88 kDa cell survival factor). A cell-free assay highlighted proMMP-12 activation by O2-. Accordingly, NGR-peptide's downregulation of 88 kDa progranulin protein was prevented by BAPTA and NAC. Conversely, AML blast resistance to NGR-peptide is associated with the expression of a distinct, 105 kDa progranulin isoform. These results indicate that CNGRC-GG-D(KLAKLAK)2 induces death in AML cells through the Ca2+-mitochondria-O2.-pathway, and support the link between proMMP-12 activation and progranulin cleavage during cell death. Our findings may have implications for the understanding of tumour biology and treatment.

  1. Properties of blue emitting CaAl2O4:Eu2+, Nd3+ phosphor by optimizing the amount of flux and fuel

    NASA Astrophysics Data System (ADS)

    Wako, A. H.; Dejene, B. F.; Swart, H. C.

    2014-04-01

    Long afterglow CaAl2O4:0.03Eu2+, 0.03Nd3+ phosphor was prepared by solution-combustion synthesis. The active role of boric acid (H3BO3) as a flux in enhancing the Eu2+ photoluminescence and the effect of a varied amount of urea (CO (NH2)2) as a fuel on the morphological, structural and photoluminescent (PL) properties of the CaAl2O4:0.03Eu2+, 0.03Nd3+ systems were investigated. The results of X-ray diffraction, scanning electron microscopy, and PL spectra revealed the influence of the dosage of urea and hence the heated process on the crystallinity, morphology, and luminescence of the phosphor. The addition of H3BO3 favoured the formation of a monoclinic CaAl2O4 phase while the variation of the amount of CO (NH2)2 showed mixed phases although still predominantly monoclinic. Both H3BO3 and CO(NH2)2 to some extent influence the luminescence intensity of the obtained phosphor but unlike the case of CO(NH2)2, the presence of H3BO3 did not evidently shift the emission peak due to no obvious change in the energy level difference of the 4f-5d levels. The broad blue emissions consisting mainly of symmetrical bands having maxima between 440 and 445 nm originate from the energy transitions between the ground state (4f7) and the excited state (4f65d1) of the Eu2+ ions while the narrow emissions in the red region (600-630 nm) arise from the 5D0→7F2 transitions of the remnant unreduced Eu3+ions. Higher concentrations of H3BO3 (0.228 mol and 0.285 mol) reduce both intensity and lifetime of the phosphor. The optimized content of H3BO3 was 0.171 mol for the obtained phosphor with the best optical properties.

  2. An Investigation of Armenite, BaCa2Al6Si9O302H2O.H2O Molecules and H Bonding in Microporous Silicates

    NASA Astrophysics Data System (ADS)

    Geiger, C. A.; Gatta, G.; Xue, X.; McIntyre, G.

    2012-12-01

    The crystal chemistry of armenite, ideally BaCa2Al6Si9O30.2H2O, a double-ring structure belonging to the milarite group, was studied to better understand the nature of extra-framework "Ca-oxygen-anion-H2O-molecule quasi-clusters" and H bonding behavior in microporous silicates. Neutron and X-ray single-crystal diffraction and IR powder and 1H NMR spectroscopic measurements were made. Four crystallographically independent Ca and H2O molecule sites were refined from the diffraction data, whereby both sites appear to have partial occupancies such that locally a Ca atom can have only a single H2O molecule bonded to it through an ion-dipole interaction. The Ca cation is further bonded to six O atoms of the framework forming a quasi cluster around it. The neutron results give the first static description of the protons in armenite, allowing bond distances and angles relating to the H2O molecules and H bonds to be determined. The IR spectrum of armenite is characterized in the OH-stretching region at RT by two broad bands at roughly 3470 and 3410 cm-1 and by a single H2O bending mode at 1654 cm-1. At 10 K four intense OH bands are located at 3479, 3454, 3401 and 3384 cm-1 and two H2O bending modes at 1650 and 1606 cm-1. The 1H MAS NMR spectrum shows a single strong resonance near 5.3 ppm and a smaller one near 2.7 ppm. The former can be assigned to H2O molecules bonded to Ca and the latter to weakly bonded H2O located at a site at the center of the structural double ring and it is partially occupied. The nature of H bonding in the microporous Ca-bearing zeolites scolecite, wairakite and epistilbite are also analyzed. The average OH stretching wavenumber shown by the IR spectra of armenite (~3435 cm-1) and scolecite (~3430 cm-1) are similar, while the average OH wavenumbers for wairakite (~3475 cm-1) and epistilbite (~3500 cm-1) are greater. In all cases the average OH stretching wavenumber is more similar to that of liquid water (~3400 cm-1) than of ice (~3220 cm-1). The

  3. Estimation of the solubility product of hydrocalumite-hydroxide, a layered double hydroxide with the formula of [Ca2Al(OH)6]OH·nH2O

    NASA Astrophysics Data System (ADS)

    Gácsi, Attila; Kutus, Bence; Kónya, Zoltán; Kukovecz, Ákos; Pálinkó, István; Sipos, Pál

    2016-11-01

    From aqueous NaOH/Ca(OH)2/NaAl(OH)4 mixtures, after allowing short reaction times we observed the precipitation of Ca(OH)2(s) at lower, and a mixture of Ca(OH)2(s) and a layered double hydroxide, hydrocalumite (HC) at higher aluminate concentrations. From the maximum aluminate concentration, at which the equilibrium solid phase is still portlandite (i.e., further increase in the aluminate concentration results in HC appearing in the precipitate beside the portlandite), the concentration based solubility products of two polymorphs of HC with the formula of [Ca2Al(OH)6]OH·nH2O (differing in n) has been estimated and was found to be log LHC=-11.4 at 25 °C and -12.1 at 75 °C, respectively (where LHC=[Ca2+]2[Al(OH)4-][OH-]3) and at constant ionic strength (I=1 M NaCl). To the best of our knowledge, this is the first published estimate for the solubility product of hydrocalumite. Additionally, from the composition obtained for NaOH/Ca(OH)2/NaAl(OH)4 mother liquors in equilibrium with Ca(OH)2(s), attempts were made to extract the formation constant of the ion pair CaAl(OH)4+. It was found, that the effects caused by the supposed formation of this solution species are too small to be reliably determined, which allowed an upper estimate for its formation constant, K, to be suggested in the temperature range of 25-75 °C (K<200 and 40 M-1 at 25 and 75 °C, respectively).

  4. Giant dielectric response and low dielectric loss in Al{sub 2}O{sub 3} grafted CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics

    SciTech Connect

    Rajabtabar-Darvishi, A.; Bayati, R. E-mail: mbayati@ncsu.edu; Sheikhnejad-Bishe, O.; Wang, L. D.; Li, W. L.; Sheng, J.; Fei, W. D. E-mail: mbayati@ncsu.edu

    2015-03-07

    This study sheds light on the effect of alumina on dielectric constant and dielectric loss of novel CaCu{sub 3}Ti{sub 4}O{sub 12} composite ceramics. Alumina, at several concentrations, was deposited on the surface of CaCu{sub 3}Ti{sub 4}O{sub 12} particles via sol-gel technique. The dielectric constant significantly increased for all frequencies and the dielectric loss substantially decreased for low and intermediate frequencies. These observations were attributed to the change in characteristics of grains and grain boundaries. It was found that the insulating properties of the grain boundaries are improved following the addition of Al{sub 2}O{sub 3}. The relative density of CaCu{sub 3}Ti{sub 4}O{sub 12}/Al{sub 2}O{sub 3} composite ceramics decreased compared to the pure CaCu{sub 3}Ti{sub 4}O{sub 12} and the grain size was greatly changed with the alumina content affecting the dielectric properties. With the addition of alumina into CaCu{sub 3}Ti{sub 4}O{sub 12}, tighter interfaces formed. The 6%- and 10%-alumina ceramics showed the minimum dielectric loss and the maximum dielectric constant, respectively. Both the dielectric constant and loss tangent decreased in the 20%-alumina ceramic due to the formation of CuO secondary phase. It was revealed that Al serves as an electron acceptor decreasing the electron concentration, if Al{sup 3+} ions substitute for Ti{sup 4+} ions, and as an electron donor increasing the electron concentration, if Al{sup 3+} ions substitute for Ca{sup 2+} ions. We established a processing-microstructure-properties paradigm which opens new avenues for novel applications of CaCu{sub 3}Ti{sub 4}O{sub 12}/Al{sub 2}O{sub 3} composite ceramics.

  5. Preparation and photoluminescence property of a loose powder, Ca{sub 3}Al{sub 2}O{sub 6}:Eu{sup 3+} by calcination of a layered double hydroxide precursor

    SciTech Connect

    Gao Xiaorui; Lei Lixu Lv Changgui; Sun Yueming; Zheng Hegen; Cui Yiping

    2008-08-15

    A novel red light-emitting material, Ca{sub 3}Al{sub 2}O{sub 6}:Eu{sup 3+}, which is the first example found in the Ca{sub 3}Al{sub 2}O{sub 6} host, was prepared by calcination of a layered double hydroxide precursor at 1350 deg. C. The precursor, [Ca{sub 2.9-x}Al{sub 2}Eu{sub x}(OH){sub 9.8}](NO{sub 3}){sub 2+x}.2.5H{sub 2}O, was prepared by coprecipitation of metal nitrates with sodium hydroxide. The material is a loose powder composed of irregular particles formed from aggregation of particles of a few nanometers, as shown in scanning electron microscope (SEM) images. It was found that the photoluminescence intensity reached the maximum when the calcination temperature was 1350 deg. C and the concentration of Eu{sup 3+} was 1.0%. The material emits bright red emission at 614 nm under a radiation of {lambda}=250 nm. - Graphical abstract: Calcination of a layered double hydroxide precursor produces Ca{sub 3}Al{sub 2}O{sub 6}:Eu{sup 3+}, which is very easy to be pulverized. It is proposed that Eu{sup 3+} takes the place of one Ca{sup 2+} (green spheres in the picture, pink pyramids are [AlO{sub 4}] tetrahedrons) in the cell of Ca{sub 3}Al{sub 2}O{sub 6}. The Ca{sup 2+} could be any one of the bigger green spheres without inversion symmetry, and emits red light under a UV radiation of {lambda}=250 nm. Display Omitted.

  6. Primary fragmentation pathways of gas phase [M(uracil-H)(uracil)]+ complexes (M=Zn, Cu, Ni, Co, Fe, Mn, Cd, Pd , Mg, Ca, Sr, Ba, and Pb): loss of uracil versus HNCO.

    PubMed

    Ali, Osama Y; Randell, Nicholas M; Fridgen, Travis D

    2012-04-23

    Complexes formed between metal dications, the conjugate base of uracil, and uracil are investigated by sustained off-resonance irradiation collision-induced dissociation (SORI-CID) in a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. Positive-ion electrospray spectra show that [M(Ura-H)(Ura)](+) (M=Zn, Cu, Ni, Co, Fe, Mn, Cd, Pd, Mg, Ca, Sr, Ba, or Pb) is the most abundant ion even at low concentrations of uracil. SORI-CID experiments show that the main primary decomposition pathway for all [M(Ura-H)(Ura)](+) , except where M=Ca, Sr, Ba, or Pb, is the loss of HNCO. Under the same SORI-CID conditions, when M is Ca, Sr, Ba, or Pb, [M(Ura-H)(Ura)](+) are shown to lose a molecule of uracil. Similar results were observed under infrared multiple-photon dissociation excitation conditions, except that [Ca(Ura-H)(Ura)](+) was found to lose HNCO as the primary fragmentation product. The binding energies between neutral uracil and [M(Ura-H)](+) (M=Zn, Cu, Ni, Fe, Cd, Pd ,Mg, Ca, Sr Ba, or Pb) are calculated by means of electronic-structure calculations. The differences in the uracil binding energies between complexes which lose uracil and those which lose HNCO are consistent with the experimentally observed differences in fragmentation pathways. A size dependence in the binding energies suggests that the interaction between uracil and [M(Ura-H)](+) is ion-dipole complexation and the experimental evidence presented supports this. PMID:22447672

  7. Synthesis and Luminescent Properties of CaSr(1-x)Al2SiO7:xEu3+ Phosphors for White Light-Emitting Diodes Applications.

    PubMed

    Hakeem, D A; Park, K

    2016-02-01

    CaSr(1-x)Al2SiO7:xEu3+ (0.01 < or = x < or = 0.12) red phosphors are prepared by the solid-state reaction method. The photoluminescence properties of the CaSr(1-x)Al2SiO7:xEu+ phosphors are studied as a function of Eu3+ content. The CaSr(1-x)Al2SiO7:xEu3+ phosphors form an orthorhombic structure with a space group of P2(1)2(1)2(1). The phosphors are effectively excited by 393 nm light. The emission spectra consist of several peaks at 575, 585, 616, 654, and 700 nm, which are attributed to the transitions from the excited 5Do to 7Fj (j = 0, 1, 2, 3, and 4) levels of Eu3+, respectively. The phosphors show intense red emission due to the 5Do --> (7)F2 transition of Eu3+. The strongest red emission is observed for the CaSr0.94Al2SiO7:0.06Eu3+ phosphor. This study proposes that the CaSr(1-x)Al2SiO7:xEu3+ red phosphors have a high potential for near ultraviolet-based white light-emitting diodes. PMID:27433657

  8. Thermomechanical and thermo-optical properties of the LiCaAlF sub 6 :Cr sup 3+ laser material (US)

    SciTech Connect

    Woods, B.W.; Payne, S.A.; Marion, J.E.; Hughes, R.S.; Davis, L.E. )

    1991-05-01

    Measurements of the intrinsic thermomechanical and thermo-optical properties of the new laser material LiCaAlF{sub 6}:Cr{sup 3+} (known as Cr:LiCAF) are performed. Thermal diffusivity, heat capacity, thermal expansion, elastic constants, fracture toughness, and dispersion and temperature variation of the refractive index are all characterized for this material. In addition, the magnitude of the thermal lensing induced in a flash-lamp-pumped laser rod of Cr:LiCAF is measured and compared with the results obtained for an alexandrite laser rod in the same laser head. We find that the thermal lensing of Cr:LiCAF is favorably small and that the thermomechanical properties are expected to be adequate for applications at low and medium average power.

  9. Solubilities of Chlorine in CaO-SiO2-Al2O3-MgO Slags: Correlation Between Sulfide and Chloride Capacities

    NASA Astrophysics Data System (ADS)

    Okeda, M.; Hasegawa, M.; Iwase, M.

    2011-04-01

    To derive a correlation between sulfide and chloride capacities through our own systematic experimental studies by using a gas equilibrium technique involving Ar-H2-H2O-HCl gas mixtures, the solubilities of chlorine were determined for CaO-SiO2-MgO-Al2O3 slags at temperatures between 1673 K and 1823 K (1400 °C and 1550 °C). As a formula to correlate sulfide and chloride capacities, the following equation that is the function of temperature only was obtainable; 2log C_{{Cl}} - log C_{{S}} = - 64.4 + {82,890/{T({{K})}}} ± 0.75 whereas chloride capacities were formulated as the function of temperature and optical basicity in the following equation: 2log C_{{Cl}} = ( {43.6 - {54,600/{T({{K})}}}} )Uplambda + ( { - 39.2 + {60,200/{T({{K})}}}} ) ± 0.5{.}

  10. Crystal growth and VUV luminescence properties of Er 3+- and Tm 3+-doped LiCaAlF 6 for detectors

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Akira; Yanagida, Takayuki; Yokota, Yuui; Yamaji, Akihiro; Fujimoto, Yutaka; Pejchal, Jan; Chani, Valery I.; Kawaguchi, Noriaki; Ishizu, Sumito; Fukuda, Kentaro; Suyama, Toshihisa; Nikl, Martin

    2010-07-01

    Er- and Tm-doped LiCaAlF 6 (LiCAF) single crystals were grown by the micro-pulling-down (μ-PD) method. The crystals were transparent, 2.0 mm in diameter and 30-40 mm in length. Neither visible inclusions nor cracks were observed. Photoluminescence spectra of Er- and Tm-doped LiCAF were measured. Broad band emission due to the Tm 3+ and Er 3+ 5d-4f transitions dominated the spectrum at 163.5 and 165 nm respectively. These emissions had shortest wavelength among the fluoride crystal hosts ever reported at room temperature experiments. The vacuum ultraviolet (VUV) luminescent crystals are attractive as scintillators for radiation detectors, which employ photosensitive gases (such as TMAE or TEA) or photocathodes (such as CsI) sensitive mostly to VUV photons.

  11. Highly improved reliability of amber light emitting diode with Ca -α-SiAlON phosphor in glass formed by gas pressure sintering for automotive applications.

    PubMed

    Yoon, Chang-Bun; Kim, Sanghyun; Choi, Sung-Woo; Yoon, Chulsoo; Ahn, Sang Hyeon; Chung, Woon Jin

    2016-04-01

    Phosphor in glass (PiG) with 40 wt% of Ca-α-SiAlON phosphor and 60 wt% of Pb-free silicate glass was synthesized and mounted on a high-power blue LED to make an amber LED for automotive applications. Gas pressure sintering was applied after the conventional sintering process was used to achieve fully dense PiG plates. Changes in photoluminescence spectra and color coordination were inspected by varying the thickness of the plates that were mounted after optical polishing and machining. A trade-off between luminous flux and color purity was observed. The commercial feasibility of amber PiG packaged LED, which can satisfy international regulations for automotive components, was successfully demonstrated by examining the practical reliability under 85% humidity at an 85°C condition. PMID:27192294

  12. Sulfide Capacities of CaO-MgO-Al2O3-SiO2-CrO x Slags

    NASA Astrophysics Data System (ADS)

    Wang, Lijun; Wang, Yaxian; Chou, Kuo-chih; Seetharaman, Seshadri

    2016-08-01

    The sulfide capacities of CaO-MgO-Al2O3-SiO2-CrO x slags were measured by gas-slag equilibration method in the temperature range of 1823 K to 1898 K (1550 °C to 1625 °C) to reveal the effect of CrO x on the sulfide capacities of slags. Both higher basicity and temperature enhanced sulfide capacities. The CrO x additions in the range of 0 to 5 mass pct increased the sulfide capacity, but, further increase of CrO x contents to 7 pct was found to lower the sulfide capacity. Utilizing the relationship for estimating the ratio of Cr(II)/Cr(III) put forward by the present authors, the influence of Cr(II) on the sulfide capacities of the slags studied is discussed.

  13. First principles study of the structural, elastic, electronic and phonon properties of CdX{sub 2}O{sub 4} (X=Al, Ga, In) spinel-type oxides

    SciTech Connect

    Candan, Abdullah; Uğur, Gökay

    2014-10-06

    We have performed ab-initio calculations of the structural, electronic, elastic and dynamical properties for the spinel compounds CdX{sub 2}O{sub 4} (X=Al, Ga, In) using the plane wave pseudo-potential method within the generalized gradient approximation (GGA). The calculated lattice parameters, elastic constants for these compounds are in good agreement with the previous calculated values. The computed direct band gaps of CdAl{sub 2}O{sub 4}, CdGa{sub 2}O{sub 4} and CdIn{sub 2}O{sub 4} are 2.90 eV, 1.92 eV and 1.16 eV, respectively. The lattice vibrations were calculated by direct method. The calculated phonon dispersion curves show that all compounds are dynamically stable in the spinel structure.

  14. From atomic structure to excess entropy: a neutron diffraction and density functional theory study of CaO-Al2O3-SiO2 melts

    NASA Astrophysics Data System (ADS)

    Liu, Maoyuan; Jacob, Aurélie; Schmetterer, Clemens; Masset, Patrick J.; Hennet, Louis; Fischer, Henry E.; Kozaily, Jad; Jahn, Sandro; Gray-Weale, Angus

    2016-04-01

    Calcium aluminosilicate \\text{CaO}-\\text{A}{{\\text{l}}2}{{\\text{O}}3}-\\text{Si}{{\\text{O}}2} (CAS) melts with compositions {{≤ft(\\text{CaO}-\\text{Si}{{\\text{O}}2}\\right)}x}{{≤ft(\\text{A}{{\\text{l}}2}{{\\text{O}}3}\\right)}1-x} for x  <  0.5 and {{≤ft(\\text{A}{{\\text{l}}2}{{\\text{O}}3}\\right)}x}{{≤ft(\\text{Si}{{\\text{O}}2}\\right)}1-x} for x≥slant 0.5 are studied using neutron diffraction with aerodynamic levitation and density functional theory molecular dynamics modelling. Simulated structure factors are found to be in good agreement with experimental structure factors. Local atomic structures from simulations reveal the role of calcium cations as a network modifier, and aluminium cations as a non-tetrahedral network former. Distributions of tetrahedral order show that an increasing concentration of the network former Al increases entropy, while an increasing concentration of the network modifier Ca decreases entropy. This trend is opposite to the conventional understanding that increasing amounts of network former should increase order in the network liquid, and so decrease entropy. The two-body correlation entropy S 2 is found to not correlate with the excess entropy values obtained from thermochemical databases, while entropies including higher-order correlations such as tetrahedral order, O-M-O or M-O-M bond angles and Q N environments show a clear linear correlation between computed entropy and database excess entropy. The possible relationship between atomic structures and excess entropy is discussed.

  15. Structure and magnetic properties of Ca{sub 2}Fe{sub 1-x}Mn{sub x}AlO{sub 5+{delta}}

    SciTech Connect

    Carvalho, M.D.; Waerenborgh, J.C.; Tsipis, E.; Godinho, M.

    2008-09-15

    Ca{sub 2}Fe{sub 1-x}Mn{sub x}AlO{sub 5} (0{<=}x{<=}1) compounds were prepared by a self-combustion method under air (x=0, 0.1, 0.2 and 0.3) and nitrogen (x=0.5, 0.7 and 1.0). The samples prepared under nitrogen were successfully oxidized after short annealing under air. Both X-ray powder diffraction (XRD) Rietveld analysis and electron diffraction revealed that all compounds adopt the brownmillerite-type structure. All samples present an overall antiferromagnetic behaviour and data from magnetic measurements and Moessbauer spectroscopy allowed to conclude that the transition temperature decreases as Mn content increases for x{<=}0.3 and increases in the case of the x{>=}0.5 compounds. Except for x=1, chemical disorder due to the occupancy of both octahedral and tetrahedral sites by different metals as well as the competition between different moments' orientation induce a complex magnetic behaviour characterized by magnetic frustration and canted antiferromagnetism. Moessbauer spectroscopy and chemical titrations also allowed to conclude about the preferential oxidation of Mn{sup 3+} over Fe{sup 3+}, obtained by thermal treatment under air of the x=0.5 and 0.7 compositions. - Graphical abstract: Structure of the Ca{sub 2}Fe{sub 1-x}Mn{sub x}AlO{sub 5} compound and electron diffraction pattern obtained along the [1-bar 01] zone axis (x=0.2), showing a brownmillerite structure.

  16. Influences of CaO on Crystallization, Microstructures, and Properties of BaO-Al2O3-B2O3-SiO2 Glass-Ceramics

    NASA Astrophysics Data System (ADS)

    Li, Bo; Tang, Bo; Xu, Mingjiang

    2015-10-01

    We have developed BaO-CaO-Al2O3-B2O3-SiO2 glass-ceramics with high thermal coefficient of expansion (TCE) to overcome thermal mismatch at board level. The crystalline phases include quartz (major), cristobalite (minor), and bazirite BaZrSi3O9 (minor). Calculations from whole-pattern fitting show that the crystallinity varies slightly within the range of 33.48% to 34.89%, while the mass fraction of the phases changes remarkably with the CaO content. This indicates that CaO cannot promote crystallization of Ba-Al-B-Si glass, but effectively suppresses the phase transformation from quartz to cristobalite, making the thermal expansion curves linear. An empirical equation for the TCE versus the temperature and the amount of CaO is established. Furthermore, the densification mechanism of Ca modifiers is revealed. Due to its higher field strength than Ba, substitution of Ca increases the glass viscosity and inhibits ion diffusion. Excessive CaO is thus harmful to the density, bending strength, and electrical properties. The sample with 10 wt.% CaO sintered at 950°C exhibited high bending strength (154.1 MPa) and high TCE (12.38 ppm/°C) as well as good electrical properties ( ɛ = 6.2, tan δ = 5 × 10-4, ρ = 3.8 × 1012 Ω cm).

  17. Vibrational spectrum of katoite Ca3Al2[(OH)4]3: a periodic ab initio study.

    PubMed

    Orlando, R; Torres, F J; Pascale, F; Ugliengo, P; Zicovich-Wilson, C; Dovesi, R

    2006-01-19

    The vibrational spectrum of the Si-free katoite hydrogarnet (116 atoms in the unit cell) has been calculated at the periodic ab initio quantum mechanical level with the CRYSTAL program, by using a Gaussian type basis set and the hybrid B3LYP Hamiltonian. The harmonic frequencies at the Gamma point have been obtained by diagonalizing the mass-weighted Hessian matrix, that is evaluated by numerical differentiation of the analytical first derivatives of the energy with respect to the atomic Cartesian coordinates. The parameters controlling the numerical differentiation, as well as the numerical integration of the exchange-correlation functional for the self-consistent field (SCF) calculation, are shown to affect the obtained frequencies by less than 3 cm-1. Before diagonalization, the dynamical matrix is transformed to a block diagonal form according to the irreducible representations of the point group, so that the 345 vibrational modes are automatically classified by symmetry. Various tools are adopted (graphical representation, isotopic substitution, "freezing" part of the unit cell) that permit a complete classification of normal modes and, in particular, an analysis of the modes in terms of simple models (octahedra modes, Ca modes, H stretching, bending, rotations). The harmonic OH stretching band (48 modes) is quite narrow (20 cm-1), indicating that the interaction among OH groups is very weak. As the OH stretching modes are known to be totally separable from the other modes and strongly anharmonic, the one-dimensional Schroedinger equation for the anharmonic oscillator is solved numerically for the two extreme situations, corresponding to the vibration of one decoupled OH and of all 48 OH groups moving in phase. The anharmonic frequencies are 3682 and 3673 cm-1, respectively, in good agreement with IR experiments (a single band at 3661 cm-1 with a width at half band height of 33 cm-1) and confirming that the interaction between OH groups is extremely weak.

  18. Carbon in silicate liquids: the systems NaAlSi3O8-CO2, CaAl2Si2O8-CO2, and KAlSi3O8-CO2

    NASA Astrophysics Data System (ADS)

    Boettcher, Art; Luth, Robert W.; White, Bradford S.

    1987-11-01

    To further our knowledge of the effects of volatile components on phase relationships in aluminosilicate systems, we determined the vapor saturated solidi of albite, anorthite, and sanidine in the presence of CO2 vapor. The depression of the temperature of the solidus of albite by CO2 decreases from ˜30° C at 10 kbar, to ˜10° C at 20 kbar, to about 0 at 25 kbar, suggesting that the solubility of CO2 in NaAlSi3O8 liquid in equilibrium with solid albite decreases with increasing pressure and temperature. In contrast, CO2 lowers the temperature of the solidus of anorthite by ˜30° C at 14 kbar, and by ˜70dg C at 25 kbar. This contrasting behavior of albite and anorthite is also reflected in the behavior of melting in the absence of volatile components. Whereas albite melts congruently to a liquid of NaAl-Si3O8 composition to pressures of ˜35 kbar, anorthite melts congruently to only about 10 kbar and, at higher pressures, incongruently to corundum plus a liquid that is enriched in SiO2 and CaO and depleted in Al2O3 relative to CaAl2Si2O8. The tendency toward incongruent melting with increasing pressure in albite and anorthite produces an increase in the activity of SiO2 component in the liquid (a_{SiO_2 }^l ). We predict that this increases the ratio of molecular CO2/CO{3/2-}in these liquids, but the experimental results from other workers are mutually contradictory. Because of the positive dP/dT of the albite solidus and the negative dP/dT of the anorthite solidus, we propose that a negative temperature derivative of the solubility of molecular CO2 in plagioclase liquids may partly explain the decrease in solubility of carbon with increasing pressure in near-solidus NaAlSi3O8 liquids, which is in contrast to that in CaAl2Si2O8 liquid. Also, reaction of CO2 with NaAlSi3O8 liquid to form CO{3/2-}that is complexed with Na+ must be accompanied by a change in Al3+ from network-former to network-modifier, as Na+ is no longer abailable to charge-balance Al3+ in a

  19. Thermodynamic simulation on mineralogical composition of CaO-SiO2-Al2O3-MgO quaternary slag system.

    PubMed

    Liu, Chao; Zhang, Yu-Zhu; Li, Jie; Li, Jun-Guo; Kang, Yue

    2016-01-01

    It is necessary to elucidate the crystallization thermodynamic of mineralogical phases during the cooling process of the molten BFS with different chemical composition, because the high-melting point mineral phase maybe crystallized during the fiber forming and thereafter cooling process. Thermodynamic calculation software FactSage6.4 and the hot remelting experiments were performed to explore the influence of basicity, Al2O3 content and MgO content on the crystallization of mineralogical components and their transformation. The results showed that the main mineralography of the CaO-SiO2-Al2O3-MgO quaternary slag system was melilite, and a certain amount of anorthite and calcium metasilicate. The crystallographic temperature of melilite is increased with the increasing of basicity, MgO and Al2O3 content, which has a significant impact on the utilization performance of the mineral wool prepared with the hot blast furnace slag directly. With the increasing of basicity, there was a tendency that crystallographic amount of melilite increased to the summit and then declined, while the amount of anorthite and calcium metasilicate decreased consistently. Finally, these two mineralogical components could be replaced by magnesium rhodonite and spinel with the increasing of basicity. When the basicity and MgO content were 1.0 and 9 %, the crystallographic mass ratio of melilite and anorthite increased, while that of calcium silicate declined, and replaced by spinel finally with the increasing of Al2O3 content. When the basicity and Al2O3 content were 1.0 and 13 %, the crystallographic mass ratio of melilite increased, while that of anorthite and calcium silicate declined, and replaced by pyroxene and spinel with the increasing of MgO content. To decline fiberization temperature of the melt BFS, the basicity, MgO and Al2O3 content should be decreased during the modification process of chemical composition, because the crystallization temperature of the primary crystalline

  20. [Determination of Al, Be, Cd, Co, Cr, Mn, Ni, Pb, Se and Tl in whole blood by atomic absorption spectrometry without preliminary sample digestion].

    PubMed

    Ivanenko, N B; Ivanenko, A A; Solov'ev, N D; Navolotskiĭ, D V; Pavlova, O V; Ganeev, A A

    2014-01-01

    Methods of whole blood trace element determination by Graphite furnace atomic absorption spectrometry (in the variant of Zeeman's modulation polarization spectrometry) have been proposed. They do not require preliminary sample digestion. Furnace programs, modifiers and blood dilution factors were optimized. Seronorm™ human whole blood reference materials were used for validation. Dynamic ranges (for undiluted blood samples) were: Al 8 ¸ 210 мg/L; Be 0.3 ¸ 50 мg/L; Cd 0.2 ¸ 75 мg/L; Сo 5 ¸ 350 мg/L; Cr 10 ¸ 100 мg/L; Mn 6 ¸ 250 мg/L; Ni 10 ¸ 350 мg/L; Pb 3 ¸ 240 мg/L; Se 10 ¸ 500 мg/L; Tl 2 ¸ 600 мg/L. Precision (RSD) for the middle of dynamic range ranged from 5% for Mn to 11 for Se.

  1. Antigen S1, encoded by the MIC1 gene, is characterized as an epitope of human CD59, enabling measurement of mutagen-induced intragenic deletions in the AL cell system

    NASA Technical Reports Server (NTRS)

    Wilson, A. B.; Seilly, D.; Willers, C.; Vannais, D. B.; McGraw, M.; Waldren, C. A.; Hei, T. K.; Davies, A.; Chatterjee, A. (Principal Investigator)

    1999-01-01

    S1 cell membrane antigen is encoded by the MIC1 gene on human chromosome 11. This antigen has been widely used as a marker for studies in gene mapping or in analysis of mutagen-induced gene deletions/mutations, which utilized the human-hamster hybrid cell-line, AL-J1, carrying human chromosome 11. Evidence is presented here which identifies S1 as an epitope of CD59, a cell membrane complement inhibiting protein. E7.1 monoclonal antibody, specific for the S1 determinant, was found to react strongly with membrane CD59 in Western blotting, and to bind to purified, urinary form of CD59 in ELISAs. Cell membrane expression of S1 on various cell lines always correlated with that of CD59 when examined by immunofluorescent staining. In addition, E7.1 antibody inhibited the complement regulatory function of CD59. Identification of S1 protein as CD59 has increased the scope of the AL cell system by enabling analysis of intragenic mutations, and multiplex PCR analysis of mutated cells is described, showing variable loss of CD59 exons.

  2. Ab-initio study of the structural, linear and nonlinear optical properties of CdAl{sub 2}Se{sub 4} defect-chalcopyrite

    SciTech Connect

    Ouahrani, T.; Reshak, Ali H.; Khenata, R.; Amrani, B.; Mebrouki, M.; Otero-de-la-Roza, A.; Luana, V.

    2010-01-15

    The complex density functional theory (DFT) calculations of structural, electronic, linear and nonlinear optical properties for the defect chalcopyrite CdAl{sub 2}Se{sub 4} compound have been reported using the full potential linearized augmented plane wave (FP-LAPW) method as implemented in the WIEN2k code. We employed the Wu and Cohen generalized gradient approximation (GGA-WC), which is based on exchange-correlation energy optimization to calculate the total energy. Also we have used the Engel-Vosko GGA formalism, which optimizes the corresponding potential for band structure, density of states and the spectral features of the linear and nonlinear optical properties. This compound has a wide direct energy band gap of about 2.927 eV with both the valence band maximum and conduction band minimum located at the center of the Brillouin zone. The ground state quantities such as lattice parameters (a, c, x, y and z), bulk modulus B and its pressure derivative B' are evaluated. We have calculated the frequency-dependent complex epsilon(omega), its zero-frequency limit epsilon{sub 1}(0), refractive index n(omega), birefringence DELTAn(omega), the reflectivity R(omega) and electron energy loss function L(omega). Calculations are reported for the frequency-dependent complex second-order nonlinear optical susceptibilities. We find opposite signs of the contributions of the 2omega and 1omega inter/intra-band to the imaginary part for the dominant component through the wide optical frequency range. - Graphical abstract: Calculated band structure and total density of CdAl{sub 2}Se{sub 4}.

  3. Short-lived chlorine-36 in a Ca- and Al-rich inclusion from the Ningqiang carbonaceous chondrite

    PubMed Central

    Lin, Yangting; Guan, Yunbin; Leshin, Laurie A.; Ouyang, Ziyuan; Wang, Daode

    2005-01-01

    Excesses of sulfur-36 in sodalite, a chlorine-rich mineral, in a calcium- and aluminum-rich inclusion from the Ningqiang carbonaceous chondrite linearly correlate with chorine/sulfur ratios, providing direct evidence for the presence of short-lived chlorine-36 (with a half-life of 0.3 million years) in the early solar system. The best inferred (36Cl/35Cl)o ratios of the sodalite are ≈5 × 10-6. Different from other short-lived radionuclides, chlorine-36 was introduced into the inclusion by solid-gas reaction during secondary alteration. The alteration reaction probably took place at least 1.5 million years after the first formation of the inclusion, based on the correlated study of the 26Al-26Mg systems of the relict primary minerals and the alteration assemblages, from which we inferred an initial ratio of (36Cl/35Cl)o > 1.6 × 10-4 at the time when calcium- and aluminum-rich inclusions formed. This discovery supports a supernova origin of short-lived nuclides [Cameron, A. G. W., Hoeflich, P., Myers, P. C. & Clayton, D. D. (1995) Astrophys. J. 447, L53; Wasserburg, G. J., Gallino, R. & Busso, M. (1998) Astrophys. J. 500, L189–L193], but presents a serious challenge for local irradiation models [Shu, F. H., Shang, H., Glassgold, A. E. & Lee, T. (1997) Science 277, 1475–1479; Gounelle, M., Shu, F. H., Shang, H., Glassgold, A. E., Rehm, K. E. & Lee, T. (2001) Astrophys. J. 548, 1051–1070]. Furthermore, the short-lived 36Cl may serve as a unique fine-scale chronometer for volatile-rock interaction in the early solar system because of its close association with aqueous and/or anhydrous alteration processes. PMID:15671168

  4. Short-lived chlorine-36 in a Ca- and Al-rich inclusion from the Ningqiang carbonaceous chondrite.

    PubMed

    Lin, Yangting; Guan, Yunbin; Leshin, Laurie A; Ouyang, Ziyuan; Wang, Daode

    2005-02-01

    Excesses of sulfur-36 in sodalite, a chlorine-rich mineral, in a calcium- and aluminum-rich inclusion from the Ningqiang carbonaceous chondrite linearly correlate with chorine/sulfur ratios, providing direct evidence for the presence of short-lived chlorine-36 (with a half-life of 0.3 million years) in the early solar system. The best inferred (36Cl/35Cl)o ratios of the sodalite are approximately 5 x 10(-6). Different from other short-lived radionuclides, chlorine-36 was introduced into the inclusion by solid-gas reaction during secondary alteration. The alteration reaction probably took place at least 1.5 million years after the first formation of the inclusion, based on the correlated study of the 26Al-26Mg systems of the relict primary minerals and the alteration assemblages, from which we inferred an initial ratio of (36Cl/35Cl)o > or = 1.6 x 10(-4) at the time when calcium- and aluminum-rich inclusions formed. This discovery supports a supernova origin of short-lived nuclides [Cameron, A. G. W., Hoeflich, P., Myers, P. C. & Clayton, D. D. (1995) Astrophys. J. 447, L53; Wasserburg, G. J., Gallino, R. & Busso, M. (1998) Astrophys. J. 500, L189-L193], but presents a serious challenge for local irradiation models [Shu, F. H., Shang, H., Glassgold, A. E. & Lee, T. (1997) Science 277, 1475-1479; Gounelle, M., Shu, F. H., Shang, H., Glassgold, A. E., Rehm, K. E. & Lee, T. (2001) Astrophys. J. 548, 1051-1070]. Furthermore, the short-lived 36Cl may serve as a unique fine-scale chronometer for volatile-rock interaction in the early solar system because of its close association with aqueous and/or anhydrous alteration processes. PMID:15671168

  5. Evaluation of Existing Viscosity Data and Models and Developments of New Viscosity Model for Fully Liquid Slag in the SiO2-Al2O3-CaO-MgO System

    NASA Astrophysics Data System (ADS)

    Han, Chen; Chen, Mao; Zhang, Weidong; Zhao, Zhixing; Evans, Tim; Zhao, Baojun

    2016-10-01

    Metallurgical properties of slag are determined to a great extent by its viscosity. High-temperature viscosity measurements are time-consuming and expensive. It is necessary to develop an accurate viscosity model for blast furnace slag in the SiO2-Al2O3-CaO-MgO system using reliable viscosity data. This paper describes a systemic evaluation procedure to determine the viscosity data to be used for model development. 1780 viscosity data from 10 to 65 wt pct SiO2, 3.5 to 40 wt pct Al2O3, 2 to 60 wt pct CaO, and 2 to 38 wt pct MgO in the SiO2-Al2O3-CaO-MgO system have been accepted for model evaluation after critical reviews. The existing 14 viscosity models in SiO2-Al2O3-CaO-MgO system is also reviewed and evaluated. Based on the structure of alumina-silicate slag and evaluated viscosity data, a new viscosity model has been proposed for the system SiO2-Al2O3-CaO-MgO. A new term "probability," based on the basic oxide and electronegativity, is introduced to calculate the integral activation energy of slag. The model has been evaluated and compared with existing viscosity models in three different composition ranges in SiO2-Al2O3-CaO-MgO system for different applications. The new model reports an outstanding agreement between predictions and experimental data. The industrial implications of the new model have also been discussed in ironmaking and steelmaking processes.

  6. Evaluation of Existing Viscosity Data and Models and Developments of New Viscosity Model for Fully Liquid Slag in the SiO2-Al2O3-CaO-MgO System

    NASA Astrophysics Data System (ADS)

    Han, Chen; Chen, Mao; Zhang, Weidong; Zhao, Zhixing; Evans, Tim; Zhao, Baojun

    2016-07-01

    Metallurgical properties of slag are determined to a great extent by its viscosity. High-temperature viscosity measurements are time-consuming and expensive. It is necessary to develop an accurate viscosity model for blast furnace slag in the SiO2-Al2O3-CaO-MgO system using reliable viscosity data. This paper describes a systemic evaluation procedure to determine the viscosity data to be used for model development. 1780 viscosity data from 10 to 65 wt pct SiO2, 3.5 to 40 wt pct Al2O3, 2 to 60 wt pct CaO, and 2 to 38 wt pct MgO in the SiO2-Al2O3-CaO-MgO system have been accepted for model evaluation after critical reviews. The existing 14 viscosity models in SiO2-Al2O3-CaO-MgO system is also reviewed and evaluated. Based on the structure of alumina-silicate slag and evaluated viscosity data, a new viscosity model has been proposed for the system SiO2-Al2O3-CaO-MgO. A new term "probability," based on the basic oxide and electronegativity, is introduced to calculate the integral activation energy of slag. The model has been evaluated and compared with existing viscosity models in three different composition ranges in SiO2-Al2O3-CaO-MgO system for different applications. The new model reports an outstanding agreement between predictions and experimental data. The industrial implications of the new model have also been discussed in ironmaking and steelmaking processes.

  7. Magneto-optical spectroscopy and optical detection of EPR spectra of Yb3+ paramagnetic centers with cubic symmetry in single crystals MeF2 ( Me = Cd, Ca, Pb)

    NASA Astrophysics Data System (ADS)

    Gerasimov, K. I.; Falin, M. L.

    2009-04-01

    Cubic paramagnetic centers formed by Yb3+ impurity ions in fluorite-type crystals MeF2 ( Me = Cd, Ca, Pb) have been investigated using electron paramagnetic resonance, magnetic circular dichroism, magnetic circular polarization of luminescence, Zeeman splitting of optical absorption and luminescence lines, and optical detection of electron paramagnetic resonance. The g factors of the 2Γ7 state in the excited multiplet 2 F 5/2 of Yb3+ ions in Me F2 crystals, the hyperfine interaction constant 171 A (171Yb) for the excited multiplet 2 F 5/2 in the CaF2 crystal, and the energies and symmetry properties of all energy levels of Yb3+ ions in MeF2 crystals are determined. The crystal-field parameters for the crystals under investigation are calculated.

  8. Tuning the Mn valence state in new Ca(0.66)Mn(2-x)Al(x)O4 (x≤ 0.4) oxides: impact on magnetic and redox properties.

    PubMed

    Lesturgez, Stéphanie; Goglio, Graziella; Weill, François; N'Guyen, Olivier; Toulemonde, Olivier; Durand, Etienne; Hernandez, Julien; Demourgues, Alain

    2016-03-21

    New Ca(0.66)Mn(2-x)Al(x)O4 (x≤ 0.4) solid solutions crystallizing with the CaFe2O4-type structure (SG: Pnma) were synthesized for the first time by the glycine-nitrate process. The structures were determined on the basis of XRD Rietveld analysis and electron diffraction investigation. While the CaMn3O6 ('Ca(0.66)Mn2O4') oxide adopts a monoclinic unit cell, the Al substitution for Mn (x = 0.2, 0.4) leads to an orthorhombic cell with only two Mn atomic positions, with different valence states, and 33% of Ca sites empty. The Ca molar concentration decreases down to 0.6 in order to increase the Mn valence leading to a phase mixture, whereas a slight Ca content increase up to 0.7 leads to a decrease of Mn valence in the pure phase. The Al(3+) ions are located at a specific Mn site because their ionic radii are close to that of Mn(4+) and a more isotropic environment. The unit cell parameters and volume strongly decrease for a low Al content and tend to an asymptotic value of x = 0.33-0.4, around the limit of solubility. As the Al content increases, the Mn valence state in the same slightly distorted octahedral site increases up to 4+ whereas the other octahedral site is highly elongated and corresponds mainly to Jahn-Teller Mn(3+). At x = 0.33, these two Mn sites correspond to Mn(4+) and Mn(3+) respectively. Moreover, the aluminium content increase induces a weakening of the global antiferromagnetic long range interactions between the ferromagnetic chains. The Al substitution leads to the change of the Mn valence distribution as well as the unit cell symmetry of the CaMn3O6 phase. These 1D tunnel networks stabilizing the Mn(3+)/Mn(4+) valence states can be reduced under Ar/5%H2 between T = 300 °C and T = 600 °C (heating rate = 2 °C min(-1)) into pure Mn(2+) rocksalt solid solution despite the large difference in ionic radii. The re-oxidation leads to the same CaFe2O4-type structure and several redox cycles can be operated. The relationship between the two double

  9. Tuning the Mn valence state in new Ca(0.66)Mn(2-x)Al(x)O4 (x≤ 0.4) oxides: impact on magnetic and redox properties.

    PubMed

    Lesturgez, Stéphanie; Goglio, Graziella; Weill, François; N'Guyen, Olivier; Toulemonde, Olivier; Durand, Etienne; Hernandez, Julien; Demourgues, Alain

    2016-03-21

    New Ca(0.66)Mn(2-x)Al(x)O4 (x≤ 0.4) solid solutions crystallizing with the CaFe2O4-type structure (SG: Pnma) were synthesized for the first time by the glycine-nitrate process. The structures were determined on the basis of XRD Rietveld analysis and electron diffraction investigation. While the CaMn3O6 ('Ca(0.66)Mn2O4') oxide adopts a monoclinic unit cell, the Al substitution for Mn (x = 0.2, 0.4) leads to an orthorhombic cell with only two Mn atomic positions, with different valence states, and 33% of Ca sites empty. The Ca molar concentration decreases down to 0.6 in order to increase the Mn valence leading to a phase mixture, whereas a slight Ca content increase up to 0.7 leads to a decrease of Mn valence in the pure phase. The Al(3+) ions are located at a specific Mn site because their ionic radii are close to that of Mn(4+) and a more isotropic environment. The unit cell parameters and volume strongly decrease for a low Al content and tend to an asymptotic value of x = 0.33-0.4, around the limit of solubility. As the Al content increases, the Mn valence state in the same slightly distorted octahedral site increases up to 4+ whereas the other octahedral site is highly elongated and corresponds mainly to Jahn-Teller Mn(3+). At x = 0.33, these two Mn sites correspond to Mn(4+) and Mn(3+) respectively. Moreover, the aluminium content increase induces a weakening of the global antiferromagnetic long range interactions between the ferromagnetic chains. The Al substitution leads to the change of the Mn valence distribution as well as the unit cell symmetry of the CaMn3O6 phase. These 1D tunnel networks stabilizing the Mn(3+)/Mn(4+) valence states can be reduced under Ar/5%H2 between T = 300 °C and T = 600 °C (heating rate = 2 °C min(-1)) into pure Mn(2+) rocksalt solid solution despite the large difference in ionic radii. The re-oxidation leads to the same CaFe2O4-type structure and several redox cycles can be operated. The relationship between the two double

  10. Diffusion in silicate melts: I. Self diffusion in CaO-Al{sub 2}O{sub 3}-SiO{sub 2} at 1500{degrees}C and 1 GPa

    SciTech Connect

    Liang, Yan |; Richter, F.M.; Davis, A.M.

    1996-11-01

    Self diffusion coefficients of calcium (D{sub Ca}), aluminum (D{sub A1}), silicon (D{sub Si}), and oxygen (D{sub o}) were measured in molten CaO-Al{sub 2}O{sub 3}-SiO{sub 2} at 1500{degrees}C and 1 GPa over a range of melt compositions, using the isotope tracer method. For all but one composition, the measured self diffusion coefficients decrease in the order D{sub Ca} > D{sub Al} > D{sub o} > D{sub Si}, with D{sub Ca} {approximately} 4-19D{sub Si}, D{sub Al}, {approximately} 2D{sub Si}, and D{sub o} {approximately} 1-2D{sub Si}. The relative uncertainties, based on replicated experiments, are 8% for D{sub Ca}, 27% for D{sub Al}, 28% for D{sub Si}, and 18% for D{sub o}. Although the self diffusion coefficients of calcium, aluminum, silicon, and oxygen increase with the decrease of melt viscosity, they do not obey the Stokes-Einstein equation or the Eyring equation. 69 refs., 6 figs., 6 tabs.

  11. 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)

    Chukanov, N. V.; Zubkova, N. V.; Pekov, I. V.; Belakovskiy, D. I.; Schüller, W.; Ternes, B.; Blass, G.; Pushcharovsky, D. Yu.

    2013-12-01

    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 (-), α = 1.496(2), β = 1.498(2), γ = 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.

  12. Tissintite, (Ca, Na, □)AlSi2O6, a highly-defective, shock-induced, high-pressure clinopyroxene in the Tissint martian meteorite

    NASA Astrophysics Data System (ADS)

    Ma, Chi; Tschauner, Oliver; Beckett, John R.; Liu, Yang; Rossman, George R.; Zhuravlev, Kirill; Prakapenka, Vitali; Dera, Przemyslaw; Taylor, Lawrence A.

    2015-07-01

    Tissintite is a new vacancy-rich, high-pressure clinopyroxene, with a composition essentially equivalent to plagioclase. It was discovered in maskelynite (shocked plagioclase) and is commonly observed included within, or in contact with, shock-melt pockets in the Tissint meteorite, a depleted olivine-phyric shergottite fall from Mars. The simple composition of tissintite (An58-69) and its precursor plagioclase (An59-69) together with the limited occurrence, both spatially (only in maskelynite less than ˜25 μm of a shock melt pocket) and in terms of bulk composition, make tissintite a "goldilocks" phase. It formed during a shock event severe enough to allow nucleation and growth of vacancy-rich clinopyroxene from a melt of not too calcic and not too sodic plagioclase composition that was neither too hot nor too cold. With experimental calibration, these limitations on occurrence can be used to place strong constraints on the thermal history of a shock event. The kinetics for nucleation and growth of tissintite are probably slower for more-sodic plagioclase precursors, so tissintite is most likely to occur in depleted olivine-phyric shergottites like Tissint and other highly shocked meteorites and lunar and terrestrial rocks that consistently contained calcic plagioclase precursors in the appropriate compositional range for a shock of given intensity. Tissintite, (Ca0.45Na0.31□0.24) (Al0.97Fe0.03Mg0.01) (Si1.80Al0.20)O6, is a C 2 / c clinopyroxene, containing 42-60 mol% of the Ca-Eskola component, by far the highest known. The cell parameters are a = 9.21 (17) Å, b = 9.09 (4) Å, c = 5.20 (2) Å, β = 109.6 (9)°, V = 410 (8) Å3, Z = 4. The density is 3.32 g/cm3 and we estimate a cell volume for the Ca-Eskola end-member pyroxene of 411 ± 13 Å3, which is consistent with a previous estimate and, therefore, supports the importance of this component in clinopyroxenes from ultra-high pressure metamorphic rocks from the Earth's upper mantle. At least in C 2 / c

  13. Photo-stability and time-resolved photoluminescence study of colloidal CdSe/ZnS quantum dots passivated in Al2O3 using atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Cheng, Chih-Yi; Mao, Ming-Hua

    2016-08-01

    We report photo-stability enhancement of colloidal CdSe/ZnS quantum dots (QDs) passivated in Al2O3 thin film using the atomic layer deposition (ALD) technique. 62% of the original peak photoluminescence (PL) intensity remained after ALD. The photo-oxidation and photo-induced fluorescence enhancement effects of both the unpassivated and passivated QDs were studied under various conditions, including different excitation sources, power densities, and environment. The unpassivated QDs showed rapid PL degradation under high excitation due to strong photo-oxidation in air while the PL intensity of Al2O3 passivated QDs was found to remain stable. Furthermore, recombination dynamics of the unpassivated and passivated QDs were investigated by time-resolved measurements. The average lifetime of the unpassivated QDs decreases with laser irradiation time due to photo-oxidation. Photo-oxidation creates surface defects which reduces the QD emission intensity and enhances the non-radiative recombination rate. From the comparison of PL decay profiles of the unpassivated and passivated QDs, photo-oxidation-induced surface defects unexpectedly also reduce the radiative recombination rate. The ALD passivation of Al2O3 protects QDs from photo-oxidation and therefore avoids the reduction of radiative recombination rate. Our experimental results demonstrated that passivation of colloidal QDs by ALD is a promising method to well encapsulate QDs to prevent gas permeation and to enhance photo-stability, including the PL intensity and carrier lifetime in air. This is essential for the applications of colloidal QDs in light-emitting devices.

  14. Thermoelectric properties of metallic antiperovskites AXD3 (A=Ge, Sn, Pb, Al, Zn, Ga; X=N, C; D=Ca, Fe, Co)

    NASA Astrophysics Data System (ADS)

    Bilal, Muhammad; Ahmad, Iftikhar; Asadabadi, Saeid Jalali; Ahmad, Rashid; Maqbool, Muhammad

    2015-05-01

    In this paper we communicate the thermoelectric properties of carbon and nitrogen based metallic antiperovskites ANCa3 (A=Ge, Sn, Pb), BCFe3 (B=Al, Zn, Ga) and SnCD3 (D=Co and Fe) using the ab-initio calculations to explore efficient metallic thermoelectric materials. The consistency of the calculated results of SnCCo3 and SnCFe3 with the experimental results confirms the reliability of our theoretical calculations for the other investigated metallic antiperovskites. The results indicate that the thermopower of these materials can be enhanced by changing the chemical potential. The dimensionless figure of merit for the three nitrides approaches 0.96 at room temperature, which proves the usefulness of these materials in thermoelectric generators. Furthermore, the thermal conductivity is minimum at room temperature for chemical potential values between -0.25 μ(eV) and 0.25 μ(eV), and provides the maximum values of dimensionless figure of merit in this range. The striking feature of these studies is identifying a metallic compound, SnNCa3, with the highest value of Seebeck coefficient at room temperature out of all metals. The results anticipate that these materials could be efficient in thermoelectric generators; however, this needs experimental verification.[Figure not available: see fulltext.

  15. Phase transformation of Ca{sub 4}[Al{sub 6}O{sub 12}]SO{sub 4} and its disordered crystal structure at 1073 K

    SciTech Connect

    Kurokawa, Daisuke; Takeda, Seiya; Colas, Maggy; Asaka, Toru; Thomas, Philippe; Fukuda, Koichiro

    2014-07-01

    The phase transformation of Ca{sub 4}[Al{sub 6}O{sub 12}]SO{sub 4} and the crystal structure of its high-temperature phase were investigated by differential thermal analysis, temperature-dependent Raman spectroscopy and high-temperature X-ray powder diffraction (CuKα{sub 1}). We determined the starting temperature of the orthorhombic-to-cubic transformation during heating (=711 K) and that of the reverse transformation during cooling (=742 K). The thermal hysteresis was negative (=−31 K), suggesting the thermoelasticity of the transformation. The space group of the high temperature phase is I4{sup ¯}3m with the unit-cell dimensions of a=0.92426(2) nm and V=0.78955(2) nm{sup 3} (Z=2) at 1073 K. The initial structural model was derived by the direct methods and further refined by the Rietveld method. The final structural model showed the orientational disordering of SO{sub 4} tetrahedra. The maximum-entropy method-based pattern fitting method was used to confirm the validity of the split-atom model, in which conventional structure bias caused by assuming intensity partitioning was minimized. At around the transformation temperature during heating, the vibrational spectra, corresponding to the Raman-active SO{sub 4} internal stretching mode, showed the continuous and gradual change in the slope of full width at half maximum versus temperature curve. This strongly suggests that the orthorhombic-to-cubic phase transformation would be principally accompanied by the statistical disordering in orientation of the SO{sub 4} tetrahedra, without distinct dynamical reorientation. - Graphical abstract: (Left) Three-dimensional electron-density distributions of the SO{sub 4} tetrahedron with the split-atom model, and (right) a bird's eye view of electron densities on the plane parallel to (111). - Highlights: • Crystal structure of Ca{sub 4}[Al{sub 6}O{sub 12}]SO{sub 4} at 1073 K is determined by powder XRD. • The atom arrangements are represented by the split-atom model

  16. Wavelengths and transition rates for nl-n'l' transitions in Be-, B-, Mg-, Al-, Ca-, Zn-, Ag- and Yb-like tungsten ions

    NASA Astrophysics Data System (ADS)

    Safronova, U. I.; Safronova, A. S.

    2010-04-01

    We present a comprehensive theoretical study of atomic characteristics of eight isoelectronic sequences of tungsten ions in a broad range of wavelengths and transitions. In particular, excitation energies, oscillator strengths and transition probabilities are calculated for nl-n'l' transitions in W70 +, W69 +, W62 +, W61 +, W54 +, W44 +, W27 + and W4 + ions. Atomic structure and radiative characteristics of Be-like ([He]2lnl', n = 2, 3), B-like ([He]2l2l'2l''), Mg-like ([Ne]3l3l'), Al-like ([Ne]3l3l'3l''), Ca-like ([Ar]3d4l), Zn-like ([Ni]4l4l'), Ag-like [Kr]4d10nl) and Yb-like ([Xe]4f145l6l') tungsten ions are computed by the relativistic many-body perturbation theory (RMBPT) method. The calculations start from a 1s2 Dirac-Fock potential for Be- and B-like W, from the 1s22s22p6 Dirac-Fock potential for Mg- and Al-like W; from the 1s22s22p63s23p6 and 1s22s22p63s23p63d10 Dirac-Fock potentials for Ca- and Zn-like W, respectively. Evaluation of properties of Ag-like and Yb-like ions starts from a Dirac-Fock potential with only partially filled n = 4 shell (1s22s22p63s23p63d104s24p64d10) and n = 5 shell (1s22s22p63s23p63d104s24p64d104f145s25p6), respectively. First-order perturbation theory is used to obtain intermediate coupling coefficients, and second-order RMBPT is used to determine the matrix elements. The contributions from negative-energy states are included in the second-order E1 matrix elements to achieve agreement between length-form and velocity-form amplitudes. Our calculations present benchmark data for many yet unmeasured properties of tungsten ions and are in particular important in diagnostics of tungsten plasma of a broad range of temperatures as well as for future ITER plasmas.

  17. Role of the chemical substitution on the luminescence properties of solid solutions Ca{sub (1−x)}Cd{sub (x)}WO{sub 4} (0 ≤ x ≤1)

    SciTech Connect

    Taoufyq, A.; Mauroy, V.; Guinneton, F.; Bakiz, B.; Villain, S.; and others

    2015-10-15

    Highlights: • Luminescence can be modified by chemical substitution in solid solutions Ca{sub 1−x}Cd{sub x}WO{sub 4}. • The various emission spectra (charge transfer) were obtained under X-ray excitation. • Scheelite or wolframite solid solutions presented two types of emission spectra. • A luminescence component depended on cadmium substitution in each solid solution. • A component was only characteristic of oxyanion symmetry in each solid solution. - Abstract: We have investigated the chemical substitution effects on the luminescence properties under X-ray excitation of the solid solutions Ca{sub (1−x)}Cd{sub (x)}WO{sub 4} with 0 ≤ x ≤ 1. Two types of wide spectral bands, associated with scheelite-type or wolframite-type solid solutions, have been observed at room temperature. We decomposed each spectral band into several spectral components characterized by energies and intensities varying with composition x. One Gaussian component was characterized by an energy decreasing regularly with the composition x, while the other Gaussian component was only related to the tetrahedral or octahedral configurations of tungstate groups WO{sub 4}{sup 2−} or WO{sub 6}{sup 6−}. The luminescence intensities exhibited minimum values in the composition range x < 0.5 corresponding to scheelite-type structures, then, they regularly increased for cadmium compositions x > 0.5 corresponding to wolframite-type structures.

  18. Immunohistochemical distinction of renal cell carcinoma from other carcinomas with clear-cell histomorphology: utility of CD10 and CA-125 in addition to PAX-2, PAX-8, RCCma, and adipophilin.

    PubMed

    Mentrikoski, Mark J; Wendroth, Scott M; Wick, Mark R

    2014-10-01

    Clear-cell renal cell carcinoma (CC-RCC) is the most common primary kidney malignancy, yet this morphology is not unique to renal primary tumors, as clear-cell variants of numerous nonrenal carcinomas of varying lineages exist. Therefore, because of CC-RCC's ability to metastasize to nearly any anatomic location, ancillary studies such as immunohistochemistry are often needed to establish the diagnosis. Despite CD10 and renal cell carcinoma monoclonal antibody (RCCma) being touted as sensitive and specific markers, some have suggested that more recent stains including PAX-2, PAX-8, or adipophilin (ADP) are more robust markers of CC-RCC. In this study, 26 cases of CC-RCC, and 51 nonrenal carcinomas with clear-cell histomorphology (CCM) were stained with CD10, RCCma, PAX-2, PAX-8, and ADP. CA-125 was also included to help distinguish CC-RCC from Müllerian clear-cell carcinomas, due the known expression of PAX-2 and PAX-8 in both these entities. RCCma highlighted 77% of CC-RCC and 27% of the CCM group, whereas CD10 was positive in 85% and 25%, respectively. ADP highlighted all CC-RCC and 45% of CCMs. PAX-2 was positive in 81% of CC-RCC and 24% of CCM, whereas PAX-8 stained 100% of CC-RCC and 39% of CCM. Müllerian-derived tumors (clear-cell carcinomas of the ovary, vagina, and cervix) were positive with PAX-2 and PAX-8 in 69% and 100% of cases, respectively. No cases of CC-RCC stained with CA-125, whereas 88% of the Müllerian-derived tumors were positive. In summary, although new markers such as PAX-2 and PAX-8 tend to be more sensitive markers of CC-RCC, they lose specificity when Müllerian tumors are included. Inclusion of a classic renal marker such as CD10 or RCCma in the immunohistochemical panel, as well as CA-125 obviates this difficulty.

  19. Immunohistochemical distinction of renal cell carcinoma from other carcinomas with clear-cell histomorphology: utility of CD10 and CA-125 in addition to PAX-2, PAX-8, RCCma, and adipophilin.

    PubMed

    Mentrikoski, Mark J; Wendroth, Scott M; Wick, Mark R

    2014-10-01

    Clear-cell renal cell carcinoma (CC-RCC) is the most common primary kidney malignancy, yet this morphology is not unique to renal primary tumors, as clear-cell variants of numerous nonrenal carcinomas of varying lineages exist. Therefore, because of CC-RCC's ability to metastasize to nearly any anatomic location, ancillary studies such as immunohistochemistry are often needed to establish the diagnosis. Despite CD10 and renal cell carcinoma monoclonal antibody (RCCma) being touted as sensitive and specific markers, some have suggested that more recent stains including PAX-2, PAX-8, or adipophilin (ADP) are more robust markers of CC-RCC. In this study, 26 cases of CC-RCC, and 51 nonrenal carcinomas with clear-cell histomorphology (CCM) were stained with CD10, RCCma, PAX-2, PAX-8, and ADP. CA-125 was also included to help distinguish CC-RCC from Müllerian clear-cell carcinomas, due the known expression of PAX-2 and PAX-8 in both these entities. RCCma highlighted 77% of CC-RCC and 27% of the CCM group, whereas CD10 was positive in 85% and 25%, respectively. ADP highlighted all CC-RCC and 45% of CCMs. PAX-2 was positive in 81% of CC-RCC and 24% of CCM, whereas PAX-8 stained 100% of CC-RCC and 39% of CCM. Müllerian-derived tumors (clear-cell carcinomas of the ovary, vagina, and cervix) were positive with PAX-2 and PAX-8 in 69% and 100% of cases, respectively. No cases of CC-RCC stained with CA-125, whereas 88% of the Müllerian-derived tumors were positive. In summary, although new markers such as PAX-2 and PAX-8 tend to be more sensitive markers of CC-RCC, they lose specificity when Müllerian tumors are included. Inclusion of a classic renal marker such as CD10 or RCCma in the immunohistochemical panel, as well as CA-125 obviates this difficulty. PMID:25279712

  20. Impedance-based interpretations in 2-dimensional electron gas conduction formed in the LaAlO3/SrxCa1-xTiO3/SrTiO3 system

    NASA Astrophysics Data System (ADS)

    Park, Chan-Rok; Moon, Seon Young; Park, Da-Hee; Kim, Shin-Ik; Kim, Seong-Keun; Kang, Chong-Yun; Baek, Seung-Hyub; Choi, Jung-Hae; Kim, Jin-Sang; Choi, Eunsoo; Hwang, Jin-Ha

    2016-06-01

    Frequency-dependent impedance spectroscopy was applied to the 2-dimensioanl conduction transport in the LaAlO3/SrxCa1-xTiO3/SrTiO3 system. The 2-dimensional conduction modifies the electrical/dielectric responses of the LaAlO3/SrxCa1-xTiO3/SrTiO3 depending on the magnitude of the interfacial 2-dimensional resistance. The high conduction of the 2-dimensional electron gas (2DEG) layer can be described using a metallic resistor in series with two parallel RC circuits. However, the high resistance of the 2-dimensional layer drives the composite system from a finite low resistor in parallel with the surrounding dielectrics composed of LaAlO3 and SrTiO3 materials to a dielectric capacitor. This change in the resistance of the 2-dimensional layers modifies the overall impedance enabled by the presence of the interfacial layer due to SrxCa1-xTiO3, which alters the charge transport of the 2-dimensional layer from metallic to semiconducting conduction. A noticeable change is observed in the capacitance Bode plots, indicating highly amplified dielectric constants compared with the pristine SrTiO3 substrates and SrxCa1-xTiO3 with a greater Ca content.

  1. K -shell ionization cross sections of Al, Si, S, Ca, and Zn for oxygen ions in the energy range 1. 1--8 MeV

    SciTech Connect

    Geretschlaeger, M. ); Smit, Z. ); Steinbauer, E. )

    1992-03-01

    {ital K}-shell ionization cross sections induced by 1.1--8-MeV oxygen ions in Al, Si, S, Ca, and Zn were measured using different target thicknesses. The cross sections for vanishingly thin and for charge-equilibrium targets were obtained by extrapolation. The experimental results are compared to the perturbed stationary-state approximation with energy-loss, Coulomb, and relativistic corrections (ECPSSR) cross sections (Brandt and Lapicki, Phys. Rev. A 23, 1717 (1981)), to the modification of the ECPSSR theory (MECPSSR) (Benka, Geretschlaeger, and Paul, J. Phys. (Paris) Colloq. Suppl. 12, C9-251 (1987)), to the theory for direct Coulomb ionization of the 1{ital s}{sigma} molecular orbital (Montenegro and Sigaud, J. Phys. B 18, 299 (1985)), and to several semiclassical approximation codes using either the united atom binding procedure or the variational approach of Andersen {ital et} {ital al}. (Nucl. Instrum. Methods 192, 79 (1982)). The cross sections were also compared to the statistical molecular-orbital theory of inner-shell ionization for (nearly) symmetric atomic collisions (Mittelman and Wilets, Phys. Rev. 154, 12 (1967)). For fast collisions ({xi}{similar to}1), the ionization cross sections are well reproduced by theories for direct Coulomb ionization. For slower collisions ({xi}{lt}1), the experimental cross sections are systematically higher than the direct-ionization values, but they agree satisfactorily with the summed cross sections for direct Coulomb ionization and for molecular-orbital ionization. Best agreement (within a factor of 2) was found for the sums of MECPSSR and statistical cross sections.

  2. Distribution of P, K, Ca, Mg, Cd, Cu, Fe, Mn, Pb and Zn in wood and bark age classes of willows and poplars used for phytoextraction on soils contaminated by risk elements.

    PubMed

    Zárubová, Pavla; Hejcman, Michal; Vondráčková, Stanislava; Mrnka, Libor; Száková, Jiřina; Tlustoš, Pavel

    2015-12-01

    Fast-growing clones of Salix and Populus have been studied for remediation of soils contaminated by risk elements (RE) using short-rotation coppice plantations. Our aim was to assess biomass yield and distributions of elements in wood and bark of highly productive willow (S1--[Salix schwerinii × Salix viminalis] × S. viminalis, S2--Salix × smithiana clone S-218) and poplar (P1--Populus maximowiczii × Populus nigra, P2--P. nigra) clones with respect to aging. The field experiment was established in April 2008 on moderately Cd-, Pb- and Zn- contaminated soil. Shoots were harvested after four seasons (February 2012) and separated into annual classes of wood and bark. All tested clones grew on contaminated soils, with highest biomass production and lowest mortality exhibited by P1 and S2. Concentrations of elements, with exception of Ca and Pb, decreased with age and were higher in bark than in wood. The Salix clones were characterised by higher removal of Cd, Mn and Zn compared to the Populus clones. Despite generally higher RE content in young shoots, partly due to lower wood/bark ratios and higher RE concentrations in bark, the overall removal of RE was higher in older wood classes due to higher biomass yield. Thus, longer rotations seem to be more effective when phytoextraction strategy is considered. Of the four selected clones, S1 exhibited the best removal of Cd and Zn and is a good candidate for phytoextraction.

  3. Evolution of Structure and Photoluminescence by Cation Cosubstitution in Eu(2+)-Doped (Ca(1-x)Li(x))(Al(1-x)Si(1+x))N3 Solid Solutions.

    PubMed

    Wang, Ting; Xiang, Qianchuan; Xia, Zhiguo; Chen, Jun; Liu, Quanlin

    2016-03-21

    Red-emitting nitride phosphors excited with blue light have great potential for the fabrication of warm white light-emitting diodes (WLEDs). Chemical composition and structural modification are generally adopted to optimize the photoluminescence behaviors of the targeted phosphors. Herein, on the basis of the famous CaAlSiN3 phosphors, Eu(2+)-doped (Ca(1-x)Li(x))(Al(1-x)Si(1+x))N3 solid solutions via the cations' cosubstitution of (CaAl)(5+) pair by (LiSi)(5+) pair are successfully synthesized by a solid state reaction, and the lattice parameters show a linear decrease with chemical compositions suggesting the formation of the isostructural phase relationship. Four types of coordinated structure models, corresponding to different coordination environments of Eu(2+), are proposed over the course of structural evolution, which induces different structural rigidity and stability, and then they are responsible for three-stage changes of emission spectra of Eu(2+) in (Ca(1-x)Li(x))(Al(1-x)Si(1+x))N3 solid solution. PMID:26930108

  4. A novel tunable blue-green-emitting CaGdGaAl2O7:Ce(3+),Tb(3+) phosphor via energy transfer for UV-excited white LEDs.

    PubMed

    Liang, Chao; You, Hongpeng; Fu, Yibing; Teng, Xiaoming; Liu, Kai; He, Jinhua

    2015-05-01

    CaGdGaAl2O7 and CaGdGaAl2O7:Ce(3+),Tb(3+) have been synthesized by a traditional solid state reaction for the first time. The Rietveld refinement confirmed that CaGdGaAl2O7 has a tetragonal crystal system with the space group P4[combining macron]21m. The photoluminescence properties show that the obtained phosphors can be efficiently excited in the range from 330 to 400 nm, which matches perfectly with commercial UV LED chips. A tunable blue-green emitting CaGdGaAl2O7:Ce(3+),Tb(3+) phosphor has been obtained, by codoping Ce(3+) and Tb(3+) ions into the host and varying their relative ratios, and may be a good candidate for blue-green components in UV white LEDs. The luminescence properties and lifetimes reveal an efficient energy transfer from the Ce(3+) to Tb(3+) ions. The energy transfer is demonstrated to be a dipole-quadrupole mechanism, and the critical distance for Ce(3+) to Tb(3+) calculated by the concentration quenching is 12.25 Å.

  5. A novel tunable blue-green-emitting CaGdGaAl2O7:Ce(3+),Tb(3+) phosphor via energy transfer for UV-excited white LEDs.

    PubMed

    Liang, Chao; You, Hongpeng; Fu, Yibing; Teng, Xiaoming; Liu, Kai; He, Jinhua

    2015-05-01

    CaGdGaAl2O7 and CaGdGaAl2O7:Ce(3+),Tb(3+) have been synthesized by a traditional solid state reaction for the first time. The Rietveld refinement confirmed that CaGdGaAl2O7 has a tetragonal crystal system with the space group P4[combining macron]21m. The photoluminescence properties show that the obtained phosphors can be efficiently excited in the range from 330 to 400 nm, which matches perfectly with commercial UV LED chips. A tunable blue-green emitting CaGdGaAl2O7:Ce(3+),Tb(3+) phosphor has been obtained, by codoping Ce(3+) and Tb(3+) ions into the host and varying their relative ratios, and may be a good candidate for blue-green components in UV white LEDs. The luminescence properties and lifetimes reveal an efficient energy transfer from the Ce(3+) to Tb(3+) ions. The energy transfer is demonstrated to be a dipole-quadrupole mechanism, and the critical distance for Ce(3+) to Tb(3+) calculated by the concentration quenching is 12.25 Å. PMID:25833815

  6. A novel red phosphor Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} for near UV white light-emitting diodes

    SciTech Connect

    Yang, Zhigang; Zhao, Zhengyan; Shi, Yurong; Wang, Yuhua

    2013-10-15

    Graphical abstract: - Highlights: • Novel red phosphor Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} was prepared by solid-state reaction. • Excitation spectra suggested an obvious absorption in near-ultraviolet region. • Under 392 nm excitation, the phosphors exhibited a red emission at 614 nm. • Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} could be potentially applied in near UV white LEDs. - Abstract: A novel red phosphor Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} was synthesized using a solid-state reaction method, and its luminescence characteristics and charge compensators effect (Li{sup +}, Na{sup +}, K{sup +}) were investigated. The excitation spectra showed a obvious absorption in near-ultraviolet region. Under 392 nm excitation, the phosphors exhibited an intense red emission at 614 nm. The Commission Internationale de l’Eclairage (CIE) chromaticity coordinates and quantum efficiency (QE) were (0.65, 0.35) and 62.3%, respectively. The good color saturation, high quantum efficiency and small thermal-quenching properties indicate that Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} could be potentially applied in near UV white light-emitting diodes.

  7. Variation of photoluminescence features in Pr{sup 3+} doped lithium-fluoro-borate glass by changing different modifier oxides (MgO, CaO, CdO and PbO)-Judd-Ofelt theory application

    SciTech Connect

    Balakrishna, A.; Rajesh, D.; Babu, S.; Ratnakaram, Y. C.

    2015-06-24

    Pr{sup 3+} (1.0 mol%) doped different modifier oxide based six lithium-fluoro-borate glasses with chemical composition of 49Li{sub 2}B{sub 4}O{sub 7}-20BaF{sub 2}-10NaF-20MO (where M= Mg, Ca, Cd and Pb), 49Li{sub 2}B{sub 4}O{sub 7}-20BaF{sub 2}-10NaF-10MgO-10CaO and 49Li{sub 2}B{sub 4}O{sub 7}-20BaF{sub 2}-10NaF-10CdO-10PbO were prepared by conventional melt quenching technique. Judd-Ofelt theory has been applied for evaluating the Judd-Ofelt intensity parameters for Pr{sup 3+} ion in these glass compositions and are in turn to used to predict radiative properties such as radiative transition probabilities (A{sub T}), branching ratios (β) and stimulated emission cross-section (σ{sub P}). Stimulated emission cross-section (σ{sub p}) of prominent emission transitions, {sup 3}P{sub 0}→{sup 3}H{sub 4} and {sup 1}D{sub 2}→{sup 3}H{sub 4} of Pr{sup 3+} ion in all lithium-fluoro-borate glasses were calculated. Among all the emission transitions, {sup 3}P{sub 0}→{sup 3}H{sub 4} posseses higher branching ratio and stimulated emission cross-section in Mg-Ca glass, which leads to the best laser excitation at 487 nm wavelength.

  8. Raman spectroscopy of the multi-anion mineral schlossmacherite (H 3O,Ca)Al 3(AsO 4,PO 4,SO 4) 2(OH) 6

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Palmer, Sara J.; Xi, Yunfei

    2012-02-01

    The mineral schlossmacherite (H 3O,Ca)Al 3(AsO 4,PO 4,SO 4) 2(OH) 6, a multi-cation-multi-anion mineral of the beudantite mineral subgroup has been characterised by Raman spectroscopy. The mineral and related minerals functions as a heavy metal collector and is often amorphous or poorly crystalline, such that XRD identification is difficult. The Raman spectra are dominated by an intense band at 864 cm -1, assigned to the symmetric stretching mode of the AsO 43- anion. Raman bands at 809 and 819 cm -1 are assigned to the antisymmetric stretching mode of AsO 43-. The sulphate anion is characterised by bands at 1000 cm -1 ( ν1), and at 1031, 1082 and 1139 cm -1 ( ν3). Two sets of bands in the OH stretching region are observed: firstly between 2800 and 3000 cm -1 with bands observed at 2850, 2868, 2918 cm -1 and secondly between 3300 and 3600 with bands observed at 3363, 3382, 3410, 3449 and 3537 cm -1. These bands enabled the calculation of hydrogen bond distances and show a wide range of H-bond distances.

  9. Dual mode green fluorescence from Tb{sup 3+}:Ca{sub 12}Al{sub 14}O{sub 33} and its applicability as delayed fluorescence

    SciTech Connect

    Verma, R.K.; Kaur, G.; Rai, A.; Rai, S.B.

    2012-11-15

    Highlights: ► Synthesis of Yb{sup 3+}/Tb{sup 3+} co-doped Ca{sub 12}Al{sub 14}O{sub 33} phosphor. ► Dual mode emission in green area on excitation with 976 nm and 266 nm. ► Delayed fluorescence on excitation of 266 nm. ► Effect of time on delayed fluorescence. -- Abstract: A Tb{sup 3+}/Yb{sup 3+} doped calcium aluminate phosphor has been synthesized using well known combustion synthesis. The structural characterization and morphology has been studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The characteristic luminescence of Tb{sup 3+} in both upconversion and down-conversion modes, i.e. dual mode luminescence has been recorded on excitation with 976 nm and 266 nm radiation. The Stokes emission observed on 266 nm excitation also shows a characteristic of delayed fluorescence. The delayed fluorescence has been measured as a function of time and pump power. It has been correlated to the white light emission (broad continuum emission) from the host. The possible reason of association of electron hole trapping to the defect level as well as in crystal potential is suggested.

  10. Plasmon-enhanced UV and blue upconverted emissions of Tm3+-doped 12CaO·7Al2O3 nanocrystals by attaching Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhu, Hancheng; Liu, Yuxue; Zhao, Dongxing; Zhang, Meng; Yang, Jian; Yan, Duanting; Liu, Chunguang; Xu, Changshan; Layfield, Carter; Ma, Li; Wang, Xiaojun

    2016-09-01

    Tm3+-doped 12CaO·7Al2O3 (C12A7) nanocrystals with the grain size of 360 nm have been fabricated by chemical co-precipitation method. Up-converted emissions at 367, 457, 476, 648, and 682 nm, corresponding to the 1D2 → 3H6, 1D2 → 3F4, 1G4 → 3H6, 1G4 → 3F4, and 3F3 → 3H6 transitions, respectively, are observed under 808 nm excitation. Plasmon-enhanced ultraviolet (UV) and blue upconverted emissions of Tm3+-doped C12A7 nanocrystals have been achieved by attaching Ag nanoparticles onto the surface of nanocrystals. The enhancement of the upconverted emissions is highly wavelength-dependent. The emission intensities of the sample with Ag+ concentration of 5.0 × 10-3 mol/L at 367 and 476 nm are enhanced about 10 and 3 times, respectively, relative to the sample without Ag attachment. The enhancement mechanism can be ascribed to surface plasmon resonance due to the highly localized electric field and the increased radiative decay rate around Ag nanoparticles. Our results suggest that Tm3+-doped C12A7 nanocrystals by attaching Ag nanoparticles might be a potential material for upconversion, compact and tunable short-wavelength lasers.

  11. Comparison of thermoluminescence characteristics in γ-ray and C(5+) ion beam-irradiated LiCaAlF6 :Ce phosphor.

    PubMed

    Yerpude, M M; Dhoble, N S; Lochab, S P; Dhoble, S J

    2016-08-01

    We compare the thermoluminescence (TL) behavior of Ce(3+) ion-activated LiCaAlF6 exposed to γ-rays and a carbon ion beam. The reported phosphor is synthesized using an in-house precipitation method with varying concentrations of activator ion and is characterized by X-ray diffraction (XRD) and TL. Rietveld refinement is performed to study the structural statistics. The TL glow curve consists of a prominent glow peak at 232°C with three shoulders at 115, 159 and 333°C when exposed to γ-rays from a (60) Co source. When exposed to a C(5+) ion beam, the TL glow curve consists of five peaks with peak temperatures near 156, 221, 250, 287 and 330°C, and is found to vary slightly with changing fluence. Glow curve convolution deconvolution (GCCD) functions are applied to the TL curves for complete analysis of the glow curve structure and TL traps. The order of kinetics (b), activation energy (E) and frequency factor are determined using Chen's peak shape method and theoretical curves are drawn using GCCD functions. A track interaction model (TIM) is used to explain the sublinearity/saturation at higher fluences. Ion beam parameters are analyzed using Monte-Carlo simulation-based SRIM-2013 code. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26768666

  12. Comparison of thermoluminescence characteristics in γ-ray and C(5+) ion beam-irradiated LiCaAlF6 :Ce phosphor.

    PubMed

    Yerpude, M M; Dhoble, N S; Lochab, S P; Dhoble, S J

    2016-08-01

    We compare the thermoluminescence (TL) behavior of Ce(3+) ion-activated LiCaAlF6 exposed to γ-rays and a carbon ion beam. The reported phosphor is synthesized using an in-house precipitation method with varying concentrations of activator ion and is characterized by X-ray diffraction (XRD) and TL. Rietveld refinement is performed to study the structural statistics. The TL glow curve consists of a prominent glow peak at 232°C with three shoulders at 115, 159 and 333°C when exposed to γ-rays from a (60) Co source. When exposed to a C(5+) ion beam, the TL glow curve consists of five peaks with peak temperatures near 156, 221, 250, 287 and 330°C, and is found to vary slightly with changing fluence. Glow curve convolution deconvolution (GCCD) functions are applied to the TL curves for complete analysis of the glow curve structure and TL traps. The order of kinetics (b), activation energy (E) and frequency factor are determined using Chen's peak shape method and theoretical curves are drawn using GCCD functions. A track interaction model (TIM) is used to explain the sublinearity/saturation at higher fluences. Ion beam parameters are analyzed using Monte-Carlo simulation-based SRIM-2013 code. Copyright © 2016 John Wiley & Sons, Ltd.

  13. Multifunctional effect of Al2O3, SiO2 and CaO on the volatilization of PbO and PbCl2 during waste thermal treatment.

    PubMed

    Wang, Si-Jia; He, Pin-Jing; Shao, Li-Ming; Zhang, Hua

    2016-10-01

    Minerals including Al2O3, SiO2 and CaO are predominant matrixes in waste, and are thought to facilitate lead (Pb) emission control. This study distinguished the inhibition of each mineral on common stable Pb-containing compounds, including highly volatile PbCl2 and less volatile PbO. Al2O3 can lower the volatilization temperature of Pb by 29 °C due to the generation of a eutectic compound and play a minor but non-negligible role in reducing Pb volatilization. The most conspicuous inhibition effect was exerted by SiO2 and a mixture of Al2O3 and SiO2, which completely integrated PbO into the glass phase at 690 °C and prohibited its migration. In contrast, SiO2 had no significant inhibition on volatile PbCl2. CaO inhibited PbO volatilization in the absence of oxygen by controlling its diffusion, while it converted PbO to Ca2PbO4 in the presence of oxygen, thus controlling Pb diffusion and decreasing the Pb volatilization ratio and rate. The influence of CaO on PbCl2 was complex because CaO can convert PbCl2 to PbO with formation of CaCl2, and CaCl2 can also be a Cl-donor for PbO. The roles of mineral matrixes in Pb conversion were shown to be important for Pb emission control. PMID:27434254

  14. Multifunctional effect of Al2O3, SiO2 and CaO on the volatilization of PbO and PbCl2 during waste thermal treatment.

    PubMed

    Wang, Si-Jia; He, Pin-Jing; Shao, Li-Ming; Zhang, Hua

    2016-10-01

    Minerals including Al2O3, SiO2 and CaO are predominant matrixes in waste, and are thought to facilitate lead (Pb) emission control. This study distinguished the inhibition of each mineral on common stable Pb-containing compounds, including highly volatile PbCl2 and less volatile PbO. Al2O3 can lower the volatilization temperature of Pb by 29 °C due to the generation of a eutectic compound and play a minor but non-negligible role in reducing Pb volatilization. The most conspicuous inhibition effect was exerted by SiO2 and a mixture of Al2O3 and SiO2, which completely integrated PbO into the glass phase at 690 °C and prohibited its migration. In contrast, SiO2 had no significant inhibition on volatile PbCl2. CaO inhibited PbO volatilization in the absence of oxygen by controlling its diffusion, while it converted PbO to Ca2PbO4 in the presence of oxygen, thus controlling Pb diffusion and decreasing the Pb volatilization ratio and rate. The influence of CaO on PbCl2 was complex because CaO can convert PbCl2 to PbO with formation of CaCl2, and CaCl2 can also be a Cl-donor for PbO. The roles of mineral matrixes in Pb conversion were shown to be important for Pb emission control.

  15. Ladle and Continuous Casting Process Models for Reduction of SiO2 in SiO2-Al2O3-CaO Slags by Al in Fe-Al(-Si) Melts

    NASA Astrophysics Data System (ADS)

    Park, Jiwon; Sridhar, S.; Fruehan, Richard J.

    2015-02-01

    Based on a mixed control or two-phase mass transfer model considering mass transport in the metal and the slag phases, process models for ladle and continuous castor mold were developed to predict the changes in the metal and the slag chemistry and viscosity. In the ladle process model, the rate of reaction is primarily determined by stirring gas flow rate, which greatly alters the mass transports of the metal and the slag phases. In the continuous casting process model, the effects of the Al, Si, and SiO2 contents in the incoming flow of the fluid phases, casting speed, mold flux consumption rate, and depth of the liquid mold flux pool on the steady-state compositions of the metal and the mold flux were assessed.

  16. Effect of Sulfur on Liquidus Temperatures in the ZnO-"FeO"-Al2O3-CaO-SiO2-S System in Equilibrium with Metallic Iron

    NASA Astrophysics Data System (ADS)

    Zhao, Baojun; Hayes, Peter C.; Jak, Evgueni

    2011-10-01

    The phase equilibria in the ZnO-"FeO"-Al2O3-CaO-SiO2-S system have been determined experimentally in equilibrium with metallic iron. A pseudoternary section of the form ZnO-"FeO"-(Al2O3+CaO+SiO2) for CaO/SiO2 = 0.71 (weight), (CaO+SiO2)/Al2O3 = 5.0 (weight), and fixed 2.0 wt pct S concentration has been constructed. It was found that the addition of 2.0 wt pct S to the liquid extends the spinel primary phase field significantly and decreases the size of the wustite primary phase field. The liquidus temperature in the wustite primary phase field is decreased by approximately 80 K and the liquidus temperature in the spinel primary phase field is decreased by approximately 10 K with addition of 2.0 wt pct S in the composition range investigated. It was also found that iron-zinc sulfides are present in some samples in the spinel primary phase field, which are matte appearing at low zinc concentrations and sphalerite (Zn,Fe)S at higher zinc concentrations. The presence of sulfur in the slag has a minor effect on the partitioning of ZnO between the wustite and liquid phases but no effect on the partitioning of ZnO between the spinel and liquid phases.

  17. Phase Equilibrium Studies of CaO-SiO2-MgO-Al2O3 System with Binary Basicity of 1.5 Related to Blast Furnace Slag

    NASA Astrophysics Data System (ADS)

    Kou, Mingyin; Wu, Shengli; Ma, Xiaodong; Wang, Laixin; Chen, Mao; Cai, Qingwu; Zhao, Baojun

    2016-04-01

    Slags play an important role in blast furnace operation, and their compositions are based on the CaO-SiO2-MgO-Al2O3 quaternary system in many steel companies. The binary basicity (CaO/SiO2 weight ratio) of blast furnace slags, especially primary slag and bosh slag, can be as high as 1.5 or higher. Phase equilibria and liquidus temperatures in the CaO-SiO2-MgO-Al2O3 system with binary basicity of 1.50 are experimentally determined for temperatures in the range 1723 K to 1823 K (1450 °C to 1550 °C). High temperature equilibration, quenching, and electron probe X-ray microanalysis techniques have been used in the present study. The isotherms are obtained in the primary phase fields of Ca2SiO4, melilite, spinel, periclase, and merwinite related to blast furnace slags. Effects of Al2O3, MgO, and binary basicity on liquidus temperatures have been discussed. In addition, extensive solid solutions have been measured for different primary phases and will be used for development and optimization of the thermodynamic database.

  18. Experimental Determination of the Phase Diagram of the CaO-SiO2-5 pctMgO-10 pctAl2O3-TiO2 System

    NASA Astrophysics Data System (ADS)

    Shi, Junjie; Sun, Lifeng; Zhang, Bo; Liu, Xuqiang; Qiu, Jiyu; Wang, Zhaoyun; Jiang, Maofa

    2016-02-01

    Ti-bearing CaO-SiO2-MgO-Al2O3-TiO2 slags are important for the smelting of vanadium-titanium bearing magnetite. In the current study, the pseudo-melting temperatures were determined by the single-hot thermocouple technique for the specified content of 5 to 25 pct TiO2 in the CaO-SiO2-5 pctMgO-10 pctAl2O3-TiO2 phase diagram system. The 1573 K to 1773 K (1300 °C to 1500 °C) liquidus lines were first calculated based on the pseudo-melting temperatures according to thermodynamic equations in the specific primary crystal field. The phase equilibria at 1573 K (1300 °C) were determined experimentally using the high-temperature equilibrium and quench method followed by X-ray fluorescence, X-ray diffraction, scanning electron microscope, and energy dispersive X-ray spectroscope analysis; the liquid phase, melilite solid solution phase (C2MS2,C2AS)ss, and perovskite phase of CaO·TiO2 were found. Therefore, the phase diagram was constructed for the specified region of the CaO-SiO2-5 pctMgO-10 pctAl2O3-TiO2 system.

  19. Melting enthalpies of mantle peridotite: calorimetric determinations in the system CaO-MgO-Al 2O 3-SiO 2 and application to magma generation

    NASA Astrophysics Data System (ADS)

    Kojitani, Hiroshi; Akaogi, Masaki

    1997-12-01

    High-temperature drop calorimetry in the temperature range of 1398-1785 K was performed for the samples of mixtures of synthetic anorthite (An), diopside (Di), enstatite (En) and forsterite (Fo) with the same compositions as those of primary melts generated at 1.1, 3 and 4 GPa at most 10° above the solidus of anhydrous mantle peridotite in the CaO-MgO-Al 2O 3-SiO 2 system. From the differences between the heat contents ( H T-H 298) of liquid and that of crystal mixture at the liquidus temperature, melting enthalpies of the samples of 1.1, 3 and 4 GPa-primary melt compositions were determined at 1 atm to be 531 ± 39 J · g -1 at 1583 K, 604 ± 21 J · g -1 at 1703 K, 646 ± 21 J · g -1 at 1753 K, respectively. These heat of fusion values suggest that mixing enthalpy of the melt in the An-Di-En-Fo system is approximately zero within the experimental errors when we use the heat of fusion of Fo by Richet et al. (P. Richet, F. Leclerc, L. Benoist, Melting of forsterite and spinel, with implications for the glass transition of Mg 2SiO 4 liquid, Geophys. Res. Lett. 20 (1993) 1675-1678). The measured enthalpies of melting at 1 atm were converted into those for melting reactions which occur under high pressures by correcting enthalpy changes associated with solid-state mineral reactions. Correcting the effects of pressure, temperature and FeO and Na 2O components on the melting enthalpies at 1 atm, heat of fusion values of a representative mantle peridotite just above the solidus under high pressure were estimated to be 590 J at 1.1 GPa and 1523 K, 692 J at 3 GPa and 1773 K, and 807 J at 4 GPa and 1923 K for melting reactions producing liquid of 1 g, with uncertainties of 50 J. By applying these melting enthalpies to a mantle diapir model which generates present MORBs, a potential mantle temperature of 1533 K has been estimated, assuming an eruption temperature of magma of 1473 K.

  20. New phosphonate intercalates of [Ca 2Al(OH) 6]NO 3ṡ yH 2O: A synthetic and kinetic study

    NASA Astrophysics Data System (ADS)

    Williams, Gareth R.; O'Hare, Dermot

    2006-08-01

    Four organic phosphonate anions (methyl-, ethyl-, phenyl- and benzyl- (MPA, EPA, PPA, BPA)) were successfully intercalated into the [Ca 2Al(OH) 6]NO 3ṡ yH 2O ( y=1-2) layered double hydroxide (LDH) by anion exchange. The materials have been characterised by a range of physical methods including powder diffraction, elemental microanalysis, infrared spectroscopy, thermal analysis and solid state NMR. The measured interlayer expansions upon intercalation of the aromatic phosphonates suggest that the guests are intertwined between the layers, while the aliphatic guests appear to be tilted with respect to the layers. The elemental microanalysis data for all four intercalates suggests there is a significant incorporation of some of the neutral phosphonic acid as well as the anion into the structure. Solid state 31P NMR spectroscopy was employed to investigate the nature of the guest ions in some of these materials. In the MPA case, a single 31P resonance was seen, lying at a chemical shift intermediate between the neutral and monovalent forms of MPA. This implies rapid proton exchange occurs between MPA units, giving an average charge of between 0 and -1 on all guests. In the PPA case, two resonances were seen, but the chemical shifts of these were consistent with the average charge on the PPA units being between -1 and -2. The reason for this is believed to be that rapid proton exchange is occurring between the PPA anions and the interlayer water molecules: this rationalises the observed results while maintaining local electroneutrality. In situ diffraction studies were performed in order to determine the rate of intercalation of the methyl-, phenyl- and benzylphosphonate guest ions, and to investigate the reaction mechanisms. In all three cases, the reactions are direct transformations from the host to the product. In general we observe that nucleation is rate determining, but in the methyl and phenyl cases the importance of nucleation declines with increasing

  1. Isotopic Measurements in CAIs with the Nanosims: Implications to the understanding of the Formation process of Ca, Al-Rich Inclusions

    NASA Technical Reports Server (NTRS)

    Ito, M.; Messenger, S.; Walker, Robert M.

    2007-01-01

    Ca, Al-rich Inclusions (CAIs) preserve evidence of thermal events that they experienced during their formation in the early solar system. Most CAIs from CV and CO chondrites are characterized by large variations in O-isotopic compositions of primary minerals, with spinel, hibonite, and pyroxene being more O-16-rich than melilite and anorthite, with delta 17, O-18 = approx. -40%o (DELTA O-17 = delta O-17 - 0.52 x delta O-18 = approx. - 20%o ). These anomalous compositions cannot be accounted for by standard mass dependent fractionation and diffusive process of those minerals. It requires the presence of an anomalous oxygen reservoir of nucleosynthetic origin or mass independent fractionations before the formation of CAIs in the early solar system. The CAMECA NanoSIMS is a new generation ion microprobe that offers high sensitivity isotopic measurements with sub 100 nm spatial resolution. The NanoSIMS has significantly improved abilities in the study of presolar grains in various kind of meteorites and the decay products of extinct nuclides in ancient solar system matter. This instrument promises significant improvements over other conventional ion probes in the precision isotopic characterization of sub-micron scales. We report the results of our first O isotopic measurements of various CAI minerals from EK1-6-3 and 7R19-1(a) utilizing the JSC NanoSIMS 50L ion microprobe. We evaluate the measurement conditions, the instrumental mass fractionation factor (IMF) for O isotopic measurement and the accuracy of the isotopic ratio through the analysis of a San Carlos olivine standard and CAI sample of 7R19-1(a).

  2. Structure and physical properties of RT{sub 2}Cd{sub 20} (R=rare earth, T=Ni, Pd) compounds with the CeCr{sub 2}Al{sub 20}-type structure

    SciTech Connect

    Burnett, V.W.; Yazici, D.; White, B.D.; Dilley, N.R.; Friedman, A.J.; Brandom, B.; Maple, M.B.

    2014-07-01

    Eleven new compounds, R Ni{sub 2}Cd{sub 20} (R=Y, La–Nd, Sm, Gd, Tb) and R Pd{sub 2}Cd{sub 20} (R=Ce, Pr, Sm), were grown as single crystals in high temperature cadmium-rich solutions. They crystallize in the cubic CeCr{sub 2}Al{sub 20}-type structure (Fd3{sup ¯}m, Z=8) as characterized by measurements of powder X-ray diffraction. Electrical resistivity, magnetization, and specific heat measurements were performed on R Ni{sub 2}Cd{sub 20} (R=Y, La–Nd, Sm, Gd, Tb) single crystals. Whereas YNi{sub 2}Cd{sub 20} and LaNi{sub 2}Cd{sub 20} exhibit unremarkable metallic behavior, when magnetic moments from localized 4f electron states (Gd{sup 3+}–Tb{sup 3+}) are embedded into this host, they exhibit ferromagnetic order with values of the Curie temperature T{sub C} for R Ni{sub 2}Cd{sub 20} (R=Gd, and Tb) which scale with the de Gennes factor. - Graphical abstract: Specific heat divided by temperature C/T vs. T for single crystals of R Ni{sub 2}Cd{sub 20} (R=Y, La–Nd, Gd, and Tb). Left inset: Low temperature C/T vs. T{sup 2} for LaNi{sub 2}Cd{sub 20}. The solid line represents a linear fit of the data. Right inset: Low-temperature C/T data vs. T for R=Ce–Nd, Gd, and Tb; magnetic ordering temperatures are indicated by arrows. - Highlights: • R Ni{sub 2}Cd{sub 20} (R=Y, La–Nd, Sm, Gd, Tb) single crystals synthesized for the first time. • R Pd{sub 2}Cd{sub 20} (R=Ce, Pr, Sm) single crystals synthesized for the first time. • Single crystals are of good metallurgical quality (large RRR values). • NdNi{sub 2}Cd{sub 20} orders antiferromagnetically at T{sub N}=1.5 K. • R Ni{sub 2}Cd{sub 20} (R=Sm, Gd, Tb) order ferromagnetically.

  3. Spectroscopic (FT-IR, FT-Raman, 1H, 13C NMR, UV/VIS), thermogravimetric and antimicrobial studies of Ca(II), Mn(II), Cu(II), Zn(II) and Cd(II) complexes of ferulic acid

    NASA Astrophysics Data System (ADS)

    Kalinowska, M.; Piekut, J.; Bruss, A.; Follet, C.; Sienkiewicz-Gromiuk, J.; Świsłocka, R.; Rzączyńska, Z.; Lewandowski, W.

    2014-03-01

    The molecular structure of Mn(II), Cu(II), Zn(II), Cd(II) and Ca(II) ferulates (4-hydroxy-3-methoxycinnamates) was studied. The selected metal ferulates were synthesized. Their composition was established by means of elementary and thermogravimetric analysis. The following spectroscopic methods were used: infrared (FT-IR), Raman (FT-Raman), nuclear magnetic resonance (13C, 1H NMR) and ultraviolet-visible (UV/VIS). On the basis of obtained results the electronic charge distribution in studied metal complexes in comparison with ferulic acid molecule was discussed. The microbiological study of ferulic acid and ferulates toward Escherichia coli, Bacillus subtilis, Candida albicans, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris was done.

  4. Solubility and Stability of Grossular in the System CaSiO3-Al2O3-NaCl-H2O at 800 C and 10 Kbar

    NASA Astrophysics Data System (ADS)

    Newton, R. C.; Manning, C. E.

    2006-12-01

    The solubility of grossular garnet (Ca3Al2Si3O12) in H2O-NaCl solutions was investigated in a piston-cylinder apparatus at 800°C, 10 kbar, at NaCl mole fractions (XNaCl) of 0-0.4 (68.4 wt% NaCl). Starting materials included synthetic corundum and grossular, and natural, very pure wollastonite. Solubilities were determined by weight changes of single crystals and polycrystalline aggregates enclosed in perforated Pt inner capsules which were in turn sealed with H2O and halite in larger Pt outer capsules. Grossular dissolves congruently at all NaCl mole fractions. Experimental XNaCl and measured solubilities (mol/kg H2O) are: 0, 0.0055(4); 0.05, 0.030(1); 0.1, 0.056(4); 0.2, 0.079(5); 0.3, 0.100(4); 0.4, 0.127(7). The large initial solubility enhancement with NaCl indicates complexing, probably to Na-aluminates which are also probably hydrates. All quenched fluids from NaCl-bearing runs with CaSiO3 were strongly basic (pH 11-12), indicating that Ca forms chloride. NaCl also produces great enhancement of wollastonite solubility (Newton and Manning, 2006). Solubility of corundum in CaSiO3-bearing brines and of wollastonite in Al2O3-bearing brines were measured up to grossular saturation. CaSiO3 together with NaCl increases corundum solubility up to 100-fold over pure H2O at 800°C and 10 kbar, but Al2O3 added to NaCl has only a small effect on wollastonite solubility, indicating that increased pH, rather than Ca-Al-(Si) complexing, accounts for the Al2O3 enhancement. Zoisite replaces corundum in equilibrium with grossular at XNaCl ≥ 0.3; this is the only departure from the quaternary system. The high solubility of grossular and high mobility of Al2O3 in basic chloride solutions at high P and T suggest that brine infiltration may be an important factor in metasomatism of deep-crust calcareous rocks.

  5. Thermodynamic Equilibrium Calculations on Cd Transformation during Sewage Sludge Incineration.

    PubMed

    Liu, Jing-yong; Huang, Limao; Sun, Shuiyu; Ning, Xun'an; Kuo, Jiahong; Sun, Jian; Wang, Yujie; Xie, Wuming

    2016-06-01

    Thermodynamic equilibrium calculations were performed to reveal the distribution of cadmium during the sewage sludge incineration process. During sludge incineration in the presence of major minerals, such as SiO2, Al2O3 and CaO, the strongest effect was exerted by SiO2 on the Cd transformation compared with the effect of others. The stable solid product of CdSiO3 was formed easily with the reaction between Cd and SiO2, which can restrain the emissions of gaseous Cd pollutants. CdCl2 was formed more easily in the presence of chloride during incineration, thus, the volatilization of Cd was advanced by increasing chlorine content. At low temperatures, the volatilization of Cd was restrained due to the formation of the refractory solid metal sulfate. At high temperatures, the speciation of Cd was not affected by the presence of sulfur, but sulfur could affect the formation temperature of gaseous metals. PMID:27225784

  6. Al{sub 15}Ge{sub 4}Ni{sub 3}: A new intergrowth structure with Cu{sub 3}Au- and CaF{sub 2}-type building blocks

    SciTech Connect

    Reichmann, Thomas L.; Jandl, Isabella; Effenberger, Herta S.; Herzig, Peter; Richter, Klaus W.

    2015-05-15

    The new ternary compound Al{sub 15}Ge{sub 4}Ni{sub 3} (τ{sub 2} in the system Al–Ge–Ni) was synthesized in single crystalline form by a special annealing procedure from samples located in the three phase fields [L+Al+τ{sub 2}] and [L+Ge+τ{sub 2}]. The crystal structure of Al{sub 15}Ge{sub 4}Ni{sub 3} was determined by single-crystal X-ray diffraction. The compound crystallizes in a new structure type in space group I4-bar3m, Pearson Symbol cI88, cubic lattice parameter a=11.405(1) Å. Phase diagram investigations indicate stoichiometric composition without considerable homogeneity range; τ{sub 2} melts peritectically at T=444 °C. The crystal structure of Al{sub 15}Ge{sub 4}Ni{sub 3} shows a unique combination of simple Cu{sub 3}Au- and CaF{sub 2}-type building blocks: a three dimensional network of CaF{sub 2}-type units, formed by Ni and Al atoms, is interspaced by clusters (Al{sub 6}Ge{sub 8}) resembling unit cells of the Cu{sub 3}Au-type. Both structural motifs are connected by Al–Ge bonds. The ground state energy of the compound was obtained by DFT calculations and the densities of states were analyzed in detail. In addition, electron density maps were calculated in four different sections through the unit cell using the full potential linearized augmented plane-wave (FLAPW) method. The bonding situation in Al{sub 15}Ge{sub 4}Ni{sub 3} was discussed combining results from electronic calculations with the analysis of the coordination of atoms. - Graphical abstract: The new compound Al{sub 15}Ge{sub 4}Ni{sub 3} shows a unique combination of simple Cu{sub 3}Au- and CaF{sub 2}-type building blocks. - Highlights: • The crystal structure of Al{sub 15}Ge{sub 4}Ni{sub 3} (space group I4-bar3m) was determined. • It shows a unique combination of CaF{sub 2}- and Cu{sub 3}Au-type building blocks. • Electronic (DFT) calculations were performed to gain insight to chemical bonding.

  7. Structure of the quantum spin Hall states in HgTe/CdTe and InAs/GaSb/AlSb quantum wells

    NASA Astrophysics Data System (ADS)

    Klipstein, P. C.

    2015-01-01

    A solution of the k . p model is presented for bulk and quantum spin hall (QSH) edge states in semiconductor topological insulator (TI) quantum wells (QWs), bounded at the edge by an infinite wall potential. The edge states are exponentially localized, with a nonzero amplitude at the QW edge, and obey standard boundary conditions for the wave function and its derivative. Single helical edge states with spin locked to the direction of motion are found in the TI band gap (ETI) of QWs with both strong (HgTe/CdTe) and weak (InAs/GaSb/AlSb) s -p hybridization, but in the second case only below a small critical band gap, Ecrit˜1.6 meV . For ETI>Ecrit , there appear to be two degenerate states for each spin direction. It is suggested that Z2-like topological properties can still be maintained if one of these states is spurious or suppressed by disorder. The effect of interface band mixing, and band mixing due to structural inversion asymmetry and bulk inversion asymmetry is also considered. Simple model Hamiltonians are developed for the bulk and edge states which are calibrated against a bulk eight-band k . p calculation close to the TI transition. At the transition, the zero gap bulk states exhibit a spin splitting, essentially changing the Dirac point to a circle. In the TI phase, there is a small change in the dispersion of the QSH edge states. These results confirm the robustness of the QSH edge states to spatial symmetry breaking interactions.

  8. Crystalline orientations of Tl2Ba2Ca2Cu3O(x) grains on MgO, SrTiO3, and LaAlO3 substrates

    NASA Technical Reports Server (NTRS)

    Liou, S. H.; Wu, C. Y.

    1992-01-01

    Crystalline orientations of Tl2Ba2Ca2Cu3O(x) grains in magnetron sputtered films on MgO (001), SrTiO3 (001), and LaAlO3 (001) substrates were investigated by scanning electron microscopy. In contrast to the nearly single crystalline films on the lattice matched substrates SrTiO3 and LaAlO3, films on the MgO (001) substrate, being polycrystalline in nature, exhibit several preferred in-plane grain orientations. These orientations agree well with a simplified theory of near-coincidence site lattices between Tl2Ba2Ca2Cu3O(x) and MgO.

  9. Detailed structure of the carbonated peridotite solidus ledge in the system CaO-MgO- Al2O3-SiO2-CO2

    NASA Astrophysics Data System (ADS)

    Ghosh, S.; Keshav, S.; Gudfinnsson, G.; Presnall, D.

    2008-12-01

    The presence of carbonatitic melts in the sub-oceanic mantle has been inferred on the basis of geochemistry of ocean-island basalts and xenoliths, CO2-vesicles in voluminous mid-ocean ridge basalts, geophysical observations, and experimental petrology. The carbonate ledge somewhere between 2.0-3.0 GPa is a prominent feature of the solidus of carbonated peridotite. The ledge is formed by a precipitous temperature drop of the mantle solidus as the solubility of CO2 in the melt rapidly increases with increasing pressure, leading to a negative Clapeyron slope of the mantle solidus over some pressure interval. It is terminated by the appearance of crystalline carbonate, on the high-pressure side, at the expense of CO2 vapor that exists on the low pressure side. The solidus temperature of carbonated peridotite decreases by roughly 200 C at the ledge. The carbonate ledge was first noted at the solidus of carbonated peridotite in the system CaO- MgO-SiO2-CO2 [CMS-CO2], and it persists in the more complex model system CaO-MgO-Al2O3-SiO2-CO2 [CMAS-CO2]. In the system CMAS-CO2, the ledge appears to be bounded by two invariant points consisting of spinel-garnet peridotite+CO2+melt, on the low pressure side, and garnet peridotite+CO2+dolomite+melt, on the high pressure side. While the lower pressure invariant point is created by the intersection of the spinel-garnet (sp-gt) peridotite subsolidus boundary curve with the solidus of vapor-bearing peridotite, the higher pressure invariant point occurs where the CO2-bearing phase coexisting with the garnet peridotite phase assemblage changes from vapor to dolomite. The precise position and shape of the ledge and the position of the two invariant points is very significant because the temperatures at which the mantle melts and the melt compositions are dependent on the behavior of CO2, the depth interval in the Earth where carbon exists as CO2, and the onset of transformation of CO2 to crystalline carbonate in the Earth. Due to these

  10. Effect of inflammatory conditions and H2O2 on bare and coated Ti-6Al-4V surfaces: Corrosion behavior, metal ion release and Ca-P formation under long-term immersion in DMEM

    NASA Astrophysics Data System (ADS)

    Höhn, Sarah; Virtanen, Sannakaisa

    2015-12-01

    The surface oxide film and calcium-phosphate (Ca-P) formation on Ti-6Al-4V during long-term immersion in biological environments play a decisive role for the biocompatibility of the implant. Hence, the aim of the study was to evaluate the corrosion resistance, metal ion release and Ca-P formation in DMEM under physiological conditions at pH values of 7.4 and in comparison under simulated inflammatory conditions with pH 5 and in presence of H2O2. Furthermore, the influence of the immersion conditions was investigated on different surface treatments: on bare Ti-6Al-4V, after anodization, and for TiO2 nanoparticle (NP) and hydroxyapatite (HA)-incorporated TiO2-NP coatings. In the absence of H2O2, the impedance response indicated a stable thin oxide film and Ca-P formation after 28 days or 56 days depending on the coating, while under inflammatory conditions the Ca-P formation on the surface is time-delayed and dissolution of the anodized oxide layer as well as selective etching of the β-phase and phase boundaries in case of the bare alloy occur. Electrochemical impedance spectroscopy (EIS), however, indicates a good general corrosion behavior in all cases. The quantities of Ti, Al and V released from the bare and coated Ti-6Al-4V alloy markedly increased with decreasing pH (pH ≤ 5). Although the rapid increase of metal release was observed for all samples at pH 5, the quantities were significantly higher for the bare and anodized alloy than after coating with TiO2-NP or HA.

  11. Luminescence and energy-transfer properties of color-tunable Ca2Mg0.25Al1.5Si1.25O7:Ce(3+)/Eu(2+)/Tb(3+) phosphors for ultraviolet light-emitting diodes.

    PubMed

    Yuan, Bo; Song, Yanhua; Sheng, Ye; Zheng, Keyan; Huo, Qisheng; Xu, Xuechun; Zou, Haifeng

    2016-03-01

    A series of Ca2Mg0.25Al1.5Si1.25O7:Ce(3+)/Eu(2+)/Tb(3+) phosphors was been prepared via a conventional high temperature solid-state reaction and their luminescence properties were studied. The emission spectra of Ca2Mg0.25Al1.5Si1.25O7:Ce(3+),Eu(2+) and Ca2Mg0.25Al1.5Si1.25O7:Ce(3+),Tb(3+) phosphors show not only a band due to Ce(3+) ions (409 nm) but also as a band due to Eu(2+) (520 nm) and Tb(3+) (542 nm) ions. More importantly, the effective energy transfer from Ce(3+) to Eu(2+) and Tb(3+) ions was confirmed and investigated by emission/excitation spectra and luminescent decay behaviors. Furthermore, the energy level scheme and energy transfer mechanism were investigated and were demonstrated to be of resonant type via dipole-dipole (Ce(3+) to Eu(2+)) and dipole-quadrupole (Ce(3+) to Tb(3+)) reactions, respectively. Under excitation at 350 nm, the emitting color could be changed from blue to green by adjusting the relative doping concentration of Ce(3+) and Eu(2+) ions as well as Ce(3+) and Tb(3+) ions. The above results indicate that Ca2Mg0.25Al1.5Si1.25O7:Ce(3+),Eu(2+)/Tb(3+) are promising single-phase blue-to-green phosphors for application in phosphor conversion white-light-emitting diodes. PMID:26249728

  12. Synthesis, characterization of double perovskite Ca{sub 2}MSbO{sub 6} (M = Dy, Fe, Cr, Al) materials via sol–gel auto-combustion and their catalytic properties

    SciTech Connect

    Feraru, S.; Samoila, P.; Borhan, A.I.; Ignat, M.; Iordan, A.R.; Palamaru, M.N.

    2013-10-15

    Double perovskite-type oxide Ca{sub 2}MSbO{sub 6} materials, where M = Dy, Fe, Cr, and Al, were prepared by using the sol–gel auto-combustion method. The role of different B-site cations on their synthesis, structures, morphologies and catalytic properties was investigated. The progress of double-perovskite type structure formation and the disappearance of the organic phases were monitored by infrared absorption spectroscopy (FTIR). Double perovskite oxide structures were evaluated using X-ray diffraction (XRD), while the microstructure of obtained compounds was studied using scanning electron microscopy (SEM). Also, BET surface areas were measured at the liquid nitrogen temperature by nitrogen adsorption. Catalytic properties of the obtained compounds were evaluated by test reaction of hydrogen peroxide decomposition. - Highlights: • Ca{sub 2}MSbO{sub 6} double perovskites were obtained by sol–gel auto-combustion method. • Ca{sub 2}MSbO{sub 6} (M = Dy, Fe, Cr and Al) as catalysts in H{sub 2}O{sub 2} decomposition • Strong relationship between particles' shape, BET area and catalytic performance • Ca{sub 2}FeSbO{sub 6} spherical grains show superior catalytic activity.

  13. The crystal and magnetic structures of LaCa{sub 2}Fe{sub 3-x}M{sub x}O{sub 8} (M=Al, Ga, In)

    SciTech Connect

    Goossens, D.J.; Henderson, L.S.F.; Trevena, S.; Hudspeth, J.M.; Avdeev, M.; Hester, J.R.

    2012-12-15

    LaCa{sub 2}Fe{sub 3}O{sub 8} (A{sub 3}B{sub 3}O{sub 8}) is an example of a layered structure in that it consists of pairs of octahedral, perovskite-like layers alternating with a single tetrahedral layer. This work explores the doping of non-magnetic group 13 elements, M=Al, Ga and In, onto the B-site of LaCa{sub 2}Fe{sub 3-x}M{sub x}O{sub 8} as a function of x. The structural and magnetic effects are examined using a combination of neutron and X-ray diffraction. Solubility limits are established. It is found that for M=Ga the solubility limit occurs between x=1.0 and x=1.25, for the synthesis conditions used, while there is evidence for low (x<0.25) but non-zero substitution of Al. Structural refinements at x=1 suggest that Ga prefers neither the tetrahedral nor octahedral sites. The magnetic structure of LaCa{sub 2}Fe{sub 2}GaO{sub 8} has been examined using neutron diffraction at 3.2 K and room temperature. At low temperature the staggered moment per Fe{sup 3+} is 3.8(1){mu}{sub B} in LaCa{sub 2}Fe{sub 3}O{sub 8} and 4.8(1){mu}{sub B} in LaCa{sub 2}Fe{sub 2}GaO{sub 8}. The magnetic space group (P{sub 2b}2{sub 1} Prime ma Prime ) and moment direction (along c) does not appear to change with Ga substitution. - Graphical abstract: Solubility limits for group 13 elements in LaCa{sub 2}Fe{sub 3}O{sub 8}. Highlights: Black-Right-Pointing-Pointer Solubility limits for group 13 elements in LaCa{sub 2}Fe{sub 3}O{sub 8} are determined. Black-Right-Pointing-Pointer Evolution of the magnetic structure with temperature and doping is explored using neutron scattering. Black-Right-Pointing-Pointer The magnetic space group is quoted as P{sub 2b}2{sub 1}'ma' and the staggered moments are obtained for LaCa{sub 2}Fe{sub 3}O{sub 8} and LaCa{sub 2}Fe{sub 2}GaO{sub 8}.

  14. Tunable color and energy transfer in single-phase white-emitting Ca20Al26Mg3Si3O68:Ce3+,Dy3+ phosphors for UV white light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Yuan, Bo; Song, Yanhua; Sheng, Ye; Zheng, Keyan; Zhou, Xiuqing; Ma, Pingchuan; Xu, Xuechun; Zou, Haifeng

    2015-12-01

    Ce3+ and/or Dy3+ activated Ca20Al26Mg3Si3O68 phosphors were synthesized by high temperature solid state reaction and their luminescent properties were studied. There are two emissions peaking at 407 and 577 nm in the emission spectra of Ca20Al26Mg3Si3O68:Ce3+, Dy3+, which are due to the transitions of Ce3+ and Dy3+ ions, respectively. More importantly, the effective energy transfer from Ce3+ to Dy3+ ions has been confirmed and investigated by emission/excitation spectra and luminescent decay behaviors. Furthermore, the energy level scheme and mechanism of energy transfer were investigated and it was demonstrated to be resonant type via dipole-dipole reaction. Under the excitation of 345 nm, the emitting color can change from blue to white by adjusting the relative doping concentration of Ce3+ and Dy3+ ions, indicating that the phosphors Ca20Al26Mg3Si3O68:Ce3+, Dy3+ are promising single-phase white-emitting phosphors for application in pc-white LEDs.

  15. White long-lasting phosphorescence generation in a CaAl2Si2O8 : Eu2+, Mn2+, Dy3+ system through persistent energy transfer

    NASA Astrophysics Data System (ADS)

    Zhang, Jinsu; Chen, Baojiu; Sun, Jiashi; Li, Xiangping; Cheng, Lihong; Zhong, Haiyang

    2012-08-01

    Based on the persistent energy transfer principle, Mn2+ was introduced into a CaAl2Si2O8 : Eu2+/Dy3+ phosphor to achieve white long-lasting emissions. Eu2+, Mn2+ and Dy3+ tri-doped CaAl2Si2O8 phosphors with various Mn2+ concentrations were prepared via a solid-state reaction, and the crystal structure of the phosphors was identified by the x-ray diffraction technique. The luminescent properties of the Eu2+, Mn2+ and Dy3+ tri-doped CaAl2Si2O8 phosphors were studied. The energy transfer behaviour from Eu2+ to Mn2+ was analysed within the framework of Dexter theory. The physical mechanism of energy transfer was assigned to the electric dipole-quadrupole interaction. It was also demonstrated that the colour coordinates of the phosphors can be tuned from the blue region to the white region in the colour space. Furthermore, the afterglow decay and thermoluminescence curves were measured, indicating excellent phosphorescence properties of the current phosphors.

  16. Microstructure and Microwave Dielectric Properties of (1- x)MgAl2O4- x(Ca0.8Sr0.2)TiO3 Ceramics

    NASA Astrophysics Data System (ADS)

    Huang, Yafei; Yu, Jun; Shen, Chunying; Tang, Mingliang

    2016-10-01

    The microwave dielectric properties of the (1- x)MgAl2O4- x(Ca0.8Sr0.2)TiO3 ( x = 0.02 to 0.10) ceramic system synthesized by the traditional solid-state reaction method have been investigated. Spinel-structured MgAl2O4 was present together with perovskite-structured (Ca0.8Sr0.2)TiO3, and this multiphase system was verified by x-ray diffraction (XRD) and energy spectrum analyses throughout the whole compositional range. With increasing x, the temperature coefficient of resonant frequency ( τ f) and permittivity ( ɛ r) gradually increased. Consequently, near-zero τ f could be obtained for samples with x = 0.08. Excellent microwave dielectric properties with relative permittivity ( ɛ r) of 10.92, quality factor ( Q × f) of 52,563 GHz (at 12.9 GHz), and temperature coefficient of resonant frequency ( τ f) of -5.6 ppm/°C were obtained for 0.92MgAl2O4-0.08(Ca0.8Sr0.2)TiO3 composite sintered at 1440°C for 3 h, making this material a promising candidate for use in global communication satellites and radar detectors.

  17. Adsorption studies of Cd(II) onto Al 2O 3/Nb 2O 5 mixed oxide dispersed on silica matrix and its on-line preconcentration and determination by flame atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Mendonça Costa, Lucimara; Ribeiro, Emerson Schwingel; Segatelli, Mariana Gava; do Nascimento, Danielle Raphael; de Oliveira, Fernanda Midori; Tarley, César Ricardo Teixeira

    2011-05-01

    The present study describes the adsorption characteristic of Cd(II) onto Nb 2O 5/Al 2O 3 mixed oxide dispersed on silica matrix. The characterization of the adsorbent has been carried out by infrared spectroscopy (IR), scanning electronic microscopy (SEM), energy dispersive spectroscopy (EDS), energy dispersive X-ray fluorescence analysis (EDXRF) and specific surface area ( SBET). From batch experiments, adsorption kinetic of Cd(II) was described by a pseudo-second-order kinetic model. The Langmuir linear isotherm fitted to the experimental adsorption isotherm very well, and the maximum adsorption capacity was found to be 17.88 mg g -1. Using the effective material, a method for Cd(II) preconcentration at trace level was developed. The method was based on on-line adsorption of Cd(II) onto SiO 2/Al 2O 3/Nb 2O 5 at pH 8.64, in which the quantitative desorption occurs with 1.0 mol L -1 hydrochloric acid towards FAAS detector. The experimental parameters related to the system were studied by means of multivariate analysis, using 2 4 full factorial design and Doehlert matrix. The effect of SO 42-, Cu 2+, Zn 2+ and Ni 2+ foreign ions showed no interference at 1:100 analyte:interferent proportion. Under the most favorable experimental conditions, the preconcentration system provided a preconcentration factor of 18.4 times, consumption index of 1.08 mL, sample throughput of 14 h -1, concentration efficiency of 4.35 min -1, linear range from 5.0 up to 35.0 μg L -1 and limits of detection and quantification of 0.19 and 0.65 μg L -1 respectively. The feasibility of the proposed method for Cd(II) determination was assessed by analysis of water samples, cigarette sample and certified reference materials TORT-2 (Lobster hepatopancreas) and DOLT-4 (Dogfish liver).

  18. Calcioferrite with composition (Ca3.94Sr0.06)Mg1.01(Fe2.93Al1.07)(PO4)6(OH)4·12H2O

    PubMed Central

    Lafuente, Barbara; Downs, Robert T.; Yang, Hexiong; Jenkins, Robert A.

    2014-01-01

    Calcioferrite, ideally Ca4MgFe3+ 4(PO4)6(OH)4·12H2O (tetra­calcium magnesium tetrairon(III) hexakis-phosphate tetra­hydroxide dodeca­hydrate), is a member of the calcioferrite group of hydrated calcium phosphate minerals with the general formula Ca4 AB 4(PO4)6(OH)4·12H2O, where A = Mg, Fe2+, Mn2+ and B = Al, Fe3+. Calcioferrite and the other three known members of the group, montgomeryite (A = Mg, B = Al), kingsmountite (A = Fe2+, B = Al), and zodacite (A = Mn2+, B = Fe3+), usually occur as very small crystals, making their structure refinements by conventional single-crystal X-ray diffraction challenging. This study presents the first structure determination of calcioferrite with composition (Ca3.94Sr0.06)Mg1.01(Fe2.93Al1.07)(PO4)6(OH)4·12H2O based on single-crystal X-ray diffraction data collected from a natural sample from the Moculta quarry in Angaston, Australia. Calcioferrite is isostructural with montgomeryite, the only member of the group with a reported structure. The calcioferrite structure is characterized by (Fe/Al)O6 octa­hedra (site symmetries 2 and -1) sharing corners (OH) to form chains running parallel to [101]. These chains are linked together by PO4 tetra­hedra (site symmetries 2 and 1), forming [(Fe/Al)3(PO4)3(OH)2] layers stacking along [010], which are connected by (Ca/Sr)2+ cations (site symmetry 2) and Mg2+ cations (site symmetry 2; half-occupation). Hydrogen-bonding inter­actions involving the water mol­ecules (one of which is equally disordered over two positions) and OH function are also present between these layers. The relatively weaker bonds between the layers account for the cleavage of the mineral parallel to (010). PMID:24764934

  19. Mission CaMKIIγ: shuttle calmodulin from membrane to nucleus.

    PubMed

    Malik, Zulfiqar A; Stein, Ivar S; Navedo, Manuel F; Hell, Johannes W

    2014-10-01

    Neuronal plasticity depends on plasma membrane Ca(2+) influx, resulting in activity-dependent gene transcription. Calmodulin (CaM) activated by Ca(2+) initiates the nuclear events, but how CaM makes its way to the nucleus has remained elusive. Ma et al. now show that CaMKIIγ transports CaM from cell surface Ca(2+) channels to the nucleus.

  20. Bi2Sr2CaCu2O8 + x round wires with Ag/Al oxide dispersion strengthened sheaths: microstructure-properties relationships, enhanced mechanical behavior and reduced Cu depletion

    NASA Astrophysics Data System (ADS)

    Kajbafvala, Amir; Nachtrab, William; Wong, Terence; Schwartz, Justin

    2014-09-01

    Ag/Al alloys with various Al content (0.50 wt%, 0.75 wt%, 1.00 wt%, and 1.25 wt%) are made by powder metallurgy and used as the outer sheath material for Bi2Sr2CaCu2O8 + x (Bi2212)/Ag/AgAl multifilamentary round wires (RW). Bi2212/Ag/AgAl RW microstructural, mechanical and electrical properties are studied in various conditions, including as-drawn, after internal oxidation, and after partial melt processing (PMP). The results are compared with the behavior of a Bi2212/Ag/Ag0.20Mg wire of the same geometry. The grains in as-drawn Ag/Al alloys are found to be ˜25% smaller than those in the corresponding Ag/0.20 wt%Mg, but after PMP, the Ag/Al and Ag/0.20 wt%Mg grain sizes are comparable. Tensile tests show that Bi2212/Ag/AgAl green wires have yield strength (YS) of ˜115 MPa, nearly 65% higher than that of Bi2212/Ag/Ag0.20Mg. After PMP, the Bi2212/Ag/AgAl YS is about 35% greater than that of Bi2212/Ag/Ag0.20Mg. Furthermore, Bi2212/Ag/AgAl wires exhibit higher ultimate tensile strength and modulus and twice the elongation-to-failure. Atomic resolution high-angle annular dark-field scanning transmission electron microscopy, high resolution transmission electron microscopy and energy dispersive spectroscopy demonstrate the formation of nanosize MgO and Al2O3 precipitates via internal oxidation. Large spherical MgO precipitates are observed on the Ag grain boundaries of Ag/0.20 wt%Mg alloy, whereas the Al2O3 precipitates are distributed homogenously in the dispersion-strengthened (DS) Ag/Al alloy. Furthermore, it is found that less Cu diffused from the Bi2212 filaments in the Bi2212/Ag/Ag0.75Al wire during PMP than from the filaments in the Bi2212/Ag/Ag0.20Mg wire. These results show that DS Ag/Al alloy is a strong candidate for improved Bi2212 wire.

  1. Crystal structure of Kuzel's salt 3CaO.Al{sub 2}O{sub 3}.1/2CaSO{sub 4}.1/2CaCl{sub 2}.11H{sub 2}O determined by synchrotron powder diffraction

    SciTech Connect

    Mesbah, Adel; Francois, Michel; Cau-dit-Coumes, Celine; Frizon, Fabien; Leroux, Fabrice; Ravaux, Johann

    2011-05-15

    The crystal structure of Kuzel's salt has been successfully determined by synchrotron powder diffraction. It crystallizes in the rhombohedral R3-bar symmetry with a = 5.7508 (2) A, c = 50.418 (3) A, V = 1444.04 (11) A{sup 3}. Joint Rietveld refinement was realized using three X-ray powder patterns recorded with a unique wavelength and three different sample-to-detector distances. Kuzel's salt is the chloro-sulfoaluminate AFm phase and belongs to the layered double hydroxide (LDH) large family. Its structure is composed of positively charged main layer [Ca{sub 2}Al(OH){sub 6}]{sup +} and negatively charged interlayer [Cl{sub 0.50}.(SO{sub 4}){sub 0.25}.2.5H{sub 2}O]{sup -}. Chloride and sulfate anions are ordered into two independent crystallographic sites and fill successive interlayer leading to the formation of a second-stage compound. The two kinds of interlayer have the compositions [Cl.2H{sub 2}O]{sup -} and [(SO{sub 4}){sub 0.5}.3H{sub 2}O]{sup -}. The crystal structure explains why chloride and sulfate anions are not substituted and why the formation of extended solid solution in the chloro-sulfate AFm system does not occur.

  2. CdS nanoparticles sensitization of Al-doped ZnO nanorod array thin film with hydrogen treatment as an ITO/FTO-free photoanode for solar water splitting

    PubMed Central

    2012-01-01

    Aluminum-doped zinc oxide (AZO) nanorod array thin film with hydrogen treatment possesses the functions of transparent conducting oxide thin film and 1-D nanostructured semiconductor simultaneously. To enhance the absorption in the visible light region, it is sensitized by cadmium sulfide (CdS) nanoparticles which efficiently increase the absorption around 460 nm. The CdS nanoparticles-sensitized AZO nanorod array thin film with hydrogen treatment exhibits significantly improved photoelectrochemical property. After further heat treatment, a maximum short current density of 5.03 mA cm−2 is obtained under illumination. They not only are much higher than those without CdS nanoparticles sensitization and those without Al-doping and/or hydrogen treatment, but also comparable and even slightly superior to some earlier works for the CdS-sensitized zinc oxide nanorod array thin films with indium tin oxide (ITO) or fluorine-doped tin oxide (FTO) as substrates. This demonstrated successfully that the AZO nanorod array thin film with hydrogen treatment is quite suitable as an ITO/FTO-free photoanode and has great potentials in solar water splitting after sensitization by quantum dots capable of visible light absorption. PMID:23098050

  3. Shear viscosities of CaO-Al 2O 3-SiO 2 and MgO-Al 2O 3-SiO 2 liquids: Implications for the structural role of aluminium and the degree of polymerisation of synthetic and natural aluminosilicate melts

    NASA Astrophysics Data System (ADS)

    Toplis, Michael J.; Dingwell, Donald B.

    2004-12-01

    The shear viscosity of 66 liquids in the systems CaO-Al 2O 3-SiO 2 (CAS) and MgO-Al 2O 3-SiO 2 (MAS) have been measured in the ranges 1-10 4 Pa s and 10 8-10 12 Pa s. Liquids belong to series, nominally at 50, 67, and 75 mol.% SiO 2, with atomic M 2+/(M 2++ 2Al) typically in the range 0.60 to 0.40 for each isopleth. In the system CAS at 1600°C, viscosity passes through a maximum at all silica contents. The maxima are clearly centered in the peraluminous field, but the exact composition at which viscosity is a maximum is poorly defined. Similar features are observed at 900°C. In contrast, data for the system MAS at 1600°C show that viscosity decreases with decreasing Mg/(Mg + 2Al) at all silica contents, but that a maximum in viscosity must occur in the field where Mg/2Al >1. On the other hand, the viscosity at 850°C increases with decreasing Mg/(Mg + 2Al) and shows no sign of reaching a maximum, even for the most peraluminous composition studied. The data from both systems at 1600°C have been analysed assuming that shear viscosity is proportional to average bond strength and considering the equilibrium: Al-(⇔(-NBO+Al where Al [4]-(Mg,Ca) 0.5 represents a charge-balanced tetrahedrally coordinated Al; (Mg, Ca) 0.5-NBO represents a nonbridging oxygen (NBO) associated with Ca or Mg, and Al XS represents any structural role of Al that does not require a charge-balancing cation. The viscosity data were fitted using two adjustable variables: i) the equilibrium constant of the above reaction, and ii) the relative bond strength of Al XS. The values of these parameters in the system CAS suggest that Al XS remains in tetrahedral coordination, its charge deficit being satisfied by association with a three-coordinate oxygen in a structure called a tricluster. In contrast, fits to the MAS data at 1600°C infer the presence of high-coordinate Al. These interpretations are found to be consistent with independent spectroscopic and theoretical data. Furthermore, the fitted

  4. Effects of Al2O3 and MgO on Softening, Melting, and Permeation Properties of CaO-FeO-SiO2 on a Coke Bed

    NASA Astrophysics Data System (ADS)

    Ueda, Shigeru; Kon, Tatsuya; Miki, Takahiro; Kim, Sun-Joong; Nogami, Hiroshi

    2016-08-01

    In ironmaking, maintaining gas permeability in blast furnace with low coke rate operation is essential to reduce carbon emissions. The high pressure loss in the cohesive zone decreases the gas permeability and affects the productivity of blast furnace. In order to increase the gas permeability in the cohesive zone, the thickness of the cohesive layer should be decreased. For this purpose, increasing softening temperature and decreasing dripping temperature of the iron ore are desired. In this study, softening, melting, and permeation of SiO2-FeO-CaO-Al2O3-MgO on a coke bed were investigated. The oxide sample in a tablet form was heated under CO/CO2 atmosphere, and the shape of the tablet was observed. The softening and melting temperatures of the SiO2-FeO-CaO system changed with the addition of Al2O3 and MgO. Oxide tablets with and without Al2O3 softened below and above the solidus temperature, respectively. The melting temperatures varied with the ratio of CO/CO2 in the gas. The permeation temperature was independent of the melting temperature, but dependent on the wettability.

  5. Ferromagnetism and magneto-transport properties of Mn{sub 0.92}Ca{sub 0.08}As thin film grown on Al{sub 2}O{sub 3}(0001) substrate

    SciTech Connect

    Dung, Dang Duc; Van Thiet, Duong; Anh Tuan, Duong; Cho, Sunglae; Feng, Wuwei

    2014-05-07

    The epitaxial Mn{sub 0.92}Ca{sub 0.08}As thin film was grown on Al{sub 2}O{sub 3}(0001) substrate by molecular beam epitaxy. The Curie temperature (T{sub C}) around 340 K was enhanced with the addition of Ca, compared to that of bulk MnAs (T{sub C} ∼ 318 K). The maxima magnetoresistance, ∼2.08% at 0.7 T, was observed near the critical magnetic transition temperature. Moreover, the giant magnetocaloric effect was found with the maximum magnetic entropy change, ∼200 J/kgK, around 330 K at 5 T.

  6. Enhancing selectivity in stripping voltammetry by different adsorption behaviors: the use of nanostructured Mg-Al-layered double hydroxides to detect Cd(II).

    PubMed

    Xu, Ren-Xia; Yu, Xin-Yao; Gao, Chao; Liu, Jin-Huai; Compton, Richard G; Huang, Xing-Jiu

    2013-03-21

    We report the use of nanostructured layered double hydroxides (LDHs) for the highly selective and sensitive detection of Cd(2+) using anodic stripping voltammetry (ASV). In particular, the modification of a glassy carbon electrode promotes the sensitivity and selectivity towards Cd(2+) in the presence of Pb(2+), Hg(2+), Cu(2+) and Zn(2+). The electrochemical characterization and anodic stripping voltammetric performance of Cd(2+) were evaluated using cyclic voltammetry (CV) and square wave anodic stripping voltammetry (SWASV) analysis. Operational parameters, including supporting electrolytes, pH value, deposition potential and deposition time were optimized. In addition, the selectivity, interference and stability were also investigated under the optimized conditions. The results showed that the fabricated electrode possessed good selectivity, stability and reproducibility. The proposed electrochemical sensing strategy is thus expected to open new opportunities to broaden the use of ASV in analysis for detecting heavy metal ions in the environment.

  7. Optimization of Al2O3 and Li3BO3 Content as Sintering Additives of Li7-x La2.95Ca0.05ZrTaO12 at Low Temperature

    NASA Astrophysics Data System (ADS)

    Rosero-Navarro, Nataly Carolina; Miura, Akira; Higuchi, Mikio; Tadanaga, Kiyoharu

    2016-09-01

    Simultaneous effect of Al2O3 and Li3BO3 additions on sintering behavior and Li-ion conductivity of Li7-x La2.95Ca0.05ZrTaO12 (LLCZT) garnet electrolyte sintered at 900°C (10 h) is evaluated. The crystal phase and microstructure of the different composites were evaluated by x-ray diffraction and scanning electron microscopy (SEM), respectively. Electrical properties of the composites with high relative densities (95%) were examined by impedance spectroscopy. The cubic phase was formed for LLCZT sintered with 0-0.21 mol of Al2O3 and 0.70 mol-0.80 mol of Li3BO3. The excess of Al2O3 (0.22 mol) led to the formation of secondary phases. SEM observation revealed the good interconnection between LLCZT grains and the distribution of the glassy phase formed by Li3BO3 and Al2O3. Effective combination of 0.21 mol of Al2O3 and 0.80 mol of Li3BO3 produced denser material with high relative density of 95% and high Li-ion conduction of 1 × 10-4 S/cm at 32°C.

  8. Formation of finite antiferromagnetic clusters and the effect of electronic phase separation in Pr0.5Ca0.5Mn0.975Al0.025O3.

    PubMed

    Nair, Sunil; Banerjee, A

    2004-09-10

    We report the first experimental evidence of a magnetic phase arising due to the thermal blocking of antiferromagnetic clusters in the weakened charge and orbital ordered system Pr0.5Ca0.5Mn0.975Al0.025O3. The third order susceptibility (chi(3)) is used to differentiate this transition from a spin- or cluster-glass-like freezing mechanism. These clusters are found to be mesoscopic and robust to electronic phase separation which only enriches the antiphase domain walls with holes at the cost of the bulk, without changing the size of these clusters. PMID:15447376

  9. Superspin glassy behaviour of La{sub 0.7}Ca{sub 0.3}Mn{sub 0.85}Al{sub 0.15}O{sub 3} thin film

    SciTech Connect

    Kumar, Manish; Choudhary, R. J. Shukla, D. K.; Phase, D. M.

    2014-07-21

    Here, we present the low temperature magnetic behaviour of epitaxial La{sub 0.7}Ca{sub 0.3}Mn{sub 0.85}Al{sub 0.15}O{sub 3} (LCMAO) thin film through a series of DC magnetic measurements. Overall behaviour inferred from the magnetization measurements indicate that the magnetic phases created due to Al doping induced inhomogeneous distribution of Mn{sup 3+} and Mn{sup 4+} ions and oxygen vacancies present in the system act like superspins, and the strong interaction among themselves results in the superspin glassy behaviour. Interactions among the superspins are marked by the aging and zero filed memory effects. The glassy magnetic phase in LCMAO is found to follow the hierarchical model of spin glasses.

  10. Ehimeite, NaCa2Mg4CrSi6Al2O22(OH)2: The first Cr-dominant amphibole from the Akaishi Mine, Higashi-Akaishi Mountain, Ehime Prefecture, Japan

    NASA Astrophysics Data System (ADS)

    Nishio-Hamane, Daisuke; Ohnishi, Masayuki; Minakawa, Tetsuo; Yamaura, Jun-Ichi; Saito, Shohei; Kadota, Ryo

    The first Cr-dominant amphibole, ehimeite, ideally NaCa2Mg4CrSi6Al2O22(OH)2, has been found in a chromitite deposit in the Akaishi Mine, Higashi-Akaishi Mountain, Ehime Prefecture, Japan. Ehimeite occurs as prismatic crystals of up to 1.5 cm in length and 0.5 cm in width and is found in association with chromite, kämmererite (Cr-rich clinochlore), Cr-poor clinochlore, phlogopite, and uvarovite. It is transparent, emerald green to pale green in color with pale green streaks, and has a vitreous luster. Optically, it is biaxial positive with α = 1.644(2), β = 1.647(2), γ = 1.659(2), and 2Vcalc. = 53°. It has a Mohs’ hardness of 6 and densities of 3.08(3) g/cm3 (measured using heavy liquids) and 3.121 g/cm3 (calculated from powder diffraction data and the empirical formula). The empirical formula is (Na0.88K0.07)Σ0.95(Ca1.89Na0.02Mg0.09)Σ2.00(Mg4.03Cr0.62Al0.19Fe3+0.07Fe2+0.07Ti0.03)Σ5.00(Si6.14Al1.86)Σ8.00O22(OH)2 on the basis of O = 22 and OH = 2, and ehimeite mainly forms a solid solution, NaCa2Mg4(Cr, Al)Si6Al2O22(OH)2, with pargasite. It has a monoclinic unit cell with a = 9.9176(14) Å, b = 18.0009(12) Å, c = 5.2850(7) Å, β = 105.400(7)°, V = 909.6 (17) Å3, and Z = 2, and it belongs to the space group C2/m, as refined from powder XRD data. The eight strongest lines in the powder XRD pattern [d (Å), I/I0, hkl] are (3.370, 58, 150), (2.932, 43, 221), (2.697, 81, 151), (2.585, 50, 061), (2.546, 100, 202), (2.346, 42, 351), (2.156, 35, 261), and (1.514, 55, 263). The crystal structure has been refined to R1 = 0.0488 using single-crystal XRD data. It has been concluded that ehimeite in the Akaishi Mine was formed by the reaction of chromitite and the metamorphic fluid in the retrograde stage of serpentinization during the Sanbagawa metamorphism.

  11. Multinuclear high-resolution NMR study of compounds from the ternary system NaF-CaF2-AlF3: from determination to modeling of NMR parameters.

    PubMed

    Martineau, C; Body, M; Legein, C; Silly, G; Buzaré, J-Y; Fayon, F

    2006-12-11

    27Al and 23Na NMR satellite transition spectroscopy and 3Q magic-angle-spinning spectra are recorded for three compounds from the ternary NaF-CaF2-AlF3 system. The quadrupolar frequency nuQ, asymmetry parameter etaQ, and isotropic chemical shift deltaiso are extracted from the spectrum reconstructions for five aluminum and four sodium sites. The quadrupolar parameters are calculated using the LAPW-based ab initio code WIEN2k. It is necessary to perform a structure optimization of all compounds to ensure a fine agreement between experimental and calculated parameters. By a comparison of experimental and calculated values, an attribution of all of the 27Al and 23Na NMR lines to the crystallographic sites is achieved. High-speed 19F NMR MAS spectra are recorded and reconstructed for the same compounds, leading to the determination of 18 isotropic chemical shifts. The superposition model developed by Bureau et al. is used, allowing a bijective assignment of the 19F NMR lines to the crystallographic sites. PMID:17140229

  12. Crystallization control for remediation of an FetO-rich CaO-SiO2-Al2O3-MgO EAF waste slag.

    PubMed

    Jung, Sung Suk; Sohn, Il

    2014-01-01

    In this work, the crystallization behavior of synthesized FetO-rich electric arc furnace (EAF) waste slags with a basicity range of 0.7 to 1.08 was investigated. Crystal growth in the melts was observed in situ using a confocal laser scanning microscope, and a delayed crystallization for higher-basicity samples was observed in the continuous cooling transformation and time temperature transformation diagrams. This result is likely due to the polymerization of the melt structure as a result of the increased number of network-forming FeO4 and AlO4 units, as suggested by Raman analysis. The complex incorporation of Al and Fe ions in the form of AlO4 and FeO4 tetrahedral units dominant in the melt structure at a higher basicity constrained the precipitation of a magnetic, nonstoichiometric, and Fe-rich MgAlFeO4 primary phase. The growth of this spinel phase caused a clear compositional separation from amorphous phase during isothermal cooling at 1473 K leading to a clear separation between the primary and amorphous phases, allowing an efficient magnetic separation of Fe compounds from the slag for effective remediation and recycling of synthesized EAF waste slags for use in higher value-added ordinary Portland cement.

  13. Crystallization control for remediation of an FetO-rich CaO-SiO2-Al2O3-MgO EAF waste slag.

    PubMed

    Jung, Sung Suk; Sohn, Il

    2014-01-01

    In this work, the crystallization behavior of synthesized FetO-rich electric arc furnace (EAF) waste slags with a basicity range of 0.7 to 1.08 was investigated. Crystal growth in the melts was observed in situ using a confocal laser scanning microscope, and a delayed crystallization for higher-basicity samples was observed in the continuous cooling transformation and time temperature transformation diagrams. This result is likely due to the polymerization of the melt structure as a result of the increased number of network-forming FeO4 and AlO4 units, as suggested by Raman analysis. The complex incorporation of Al and Fe ions in the form of AlO4 and FeO4 tetrahedral units dominant in the melt structure at a higher basicity constrained the precipitation of a magnetic, nonstoichiometric, and Fe-rich MgAlFeO4 primary phase. The growth of this spinel phase caused a clear compositional separation from amorphous phase during isothermal cooling at 1473 K leading to a clear separation between the primary and amorphous phases, allowing an efficient magnetic separation of Fe compounds from the slag for effective remediation and recycling of synthesized EAF waste slags for use in higher value-added ordinary Portland cement. PMID:24410350

  14. Phase Relations and Elemental Distributions in the Ceramics of the Pseudo-Binary Systems CaZrTi{sub 2}O{sub 7} - LnAlO{sub 3} (Ln = Eu, Gd)

    SciTech Connect

    Mikhailenko, N.S.; Stefanovsky, S.V.; Ochkin, A.V.; Lapina, M.I.

    2007-07-01

    Zirconolite and perovskite were found to be major and minor phases respectively in the ceramics of the series (1-x) CaZrTi2O{sub 7} - x EuAlO{sub 3} and (1-x) CaZrTi{sub 2}O{sub 7} - x GdAlO{sub 3} (x = 0.25; 0.5; 0.75) produced by cold pressing and sintering at 1400, 1450 and 1500 deg. C. Zirconolite and cubic fianite-type oxide (in the Eu-bearing ceramics) were extra phases. At x = 0.25 major host phase for Eu and Gd is zirconolite accumulating of up to 90% of total Eu and Gd. With increase x value to 0.5 zirconolite remains major host phase for both Eu and Gd and accommodates almost 70% of total Eu{sub 2}O{sub 3} and about 60% of total Gd{sub 2}O{sub 3}. Perovskite becomes major phase for both Eu{sub 2}O{sub 3} and Gd{sub 2}O{sub 3} at x = 0.75 accumulating of about 66% of total Gd{sub 2}O{sub 3}. As follows from SEM/EDS data Eu and Gd contents in the zirconolite may exceed {approx}1 formula units, therefore, zirconolite ceramics may be effective matrices for actinide fraction of HLW where Am and Cm are dominant because their crystal chemical behavior is similar to behavior of Gd. (authors)

  15. Pressure induced insulator-metal transition and giant negative piezoresistance in Pr0.6Ca0.4Mn0.96Al0.04O3 polycrystal

    NASA Astrophysics Data System (ADS)

    Arumugam, S.; Thiyagarajan, R.; Kalaiselvan, G.; Sivaprakash, P.

    2016-11-01

    The effect of external hydrostatic pressure (P) on the magnetization (M) and resistivity (ρ) properties of charge-orbital (CO) ordered-insulating phase-separated manganite Pr0.6Ca0.4Mn0.96Al0.04O3 system is reported here. At ambient P, CO ordering transition and spin-canting in the AFM are observed at 223 K and 55 K respectively in M(T) and ρ(T) measurements. Application of P increases simultaneously the magnitude of magnetization (M) and transition temperature, and weakens the CO ordering in M(T) measurements up to 0.98 GPa. During ρ(T) measurements, P induces an insulator-metallic transition (TIM) at 1.02 GPa, and further increase of P up to 2.84 GPa leads to increase of TIM (dTIM/dP =21.6 K/GPa). ρ at TIM is reduced about three orders of magnitude at 2.84 GPa, and leads to the giant negative piezoresistance (~98%). These results are analyzed separately in two temperature regions i.e., below and above TIM by power function equation and small polaronic hopping model respectively. It is understood from these analyses that the application of P suppresses the Jahn-Teller distortions, electron-electron and electron-magnon scattering factors, and induces the insulator-metal transition in Pr0.6Ca0.4Mn0.96Al0.04O3 system.

  16. Phase Relations and Elemental Distribution Among Co-Existing Phases in the Ceramics of the Pseudobinary System CaZrTi{sub 2}O{sub 7}-LnAlO{sub 3} (Ln= Nd, Sm)

    SciTech Connect

    Mikhailenko, Natalia; Stefanovsky, Sergey

    2007-07-01

    In the ceramics in series (1-x) CaZrTi{sub 2}O{sub 7} - x NdAlO{sub 3} and (1-x) CaZrTi{sub 2}O{sub 7} - x SmAlO{sub 3} (x = 0.25, 0.5 and 0.75) produced by cold pressing and sintering at 1400, 1450 and 1500 deg. C zirconolite was found to be a major phase, perovskite was an extra phase and traces of residual baddeleyite occurred. At x = 0.75 the perovskite was major phase and zirconolite and cubic oxide of fianite or tazheranite type were extra phases. Major Nd and Sm host phase at x = 0.25 was found to be zirconolite (about 65% of total Nd{sub 2}O{sub 3} and 74% of total Sm{sub 2}O{sub 3}). With the x value increasing perovskite becomes major host phase for Nd and Sm accumulating of up to about 92% of total Nd and about 72% of total Sm. As follows from SEM/EDS data Nd and Sm contents in the zirconolite may reach {approx}1 formula unit (fu). (authors)

  17. Raman spectroscopy of DNA-metal complexes. II. The thermal denaturation of DNA in the presence of Sr2+, Ba2+, Mg2+, Ca2+, Mn2+, Co2+, Ni2+, and Cd2+.

    PubMed

    Duguid, J G; Bloomfield, V A; Benevides, J M; Thomas, G J

    1995-12-01

    Differential scanning calorimetry, laser Raman spectroscopy, optical densitometry, and pH potentiometry have been used to investigate DNA melting profiles in the presence of the chloride salts of Ba2+, Sr2+, Mg2+, Ca2+, Mn2+, Co2+, Ni2+, and Cd2+. Metal-DNA interactions have been observed for the molar ratio [M2+]/[PO2-] = 0.6 in aqueous solutions containing 5% by weight of 160 bp mononucleosomal calf thymus DNA. All of the alkaline earth metals, plus Mn2+, elevate the melting temperature of DNA (Tm > 75.5 degrees C), whereas the transition metals Co2+, Ni2+, and Cd2+ lower Tm. Calorimetric (delta Hcal) and van't Hoff (delta HVH) enthalpies of melting range from 6.2-8.7 kcal/mol bp and 75.6-188.6 kcal/mol cooperative unit, respectively, and entropies from 17.5 to 24.7 cal/K mol bp. The average number of base pairs in a cooperative melting unit () varied from 11.3 to 28.1. No dichotomy was observed between alkaline earth and transition DNA-metal complexes for any of the thermodynamic parameters other than their effects on Tm. These results complement Raman difference spectra, which reveal decreases in backbone order, base unstacking, distortion of glycosyl torsion angles, and rupture of hydrogen bonds, which occur after thermal denaturation. Raman difference spectroscopy shows that transition metals interact with the N7 atom of guanine in duplex DNA. A broader range of interaction sites with single-stranded DNA includes ionic phosphates, the N1 and N7 atoms of purines, and the N3 atom of pyrimidines. For alkaline earth metals, very little interaction was observed with duplex DNA, whereas spectra of single-stranded complexes are very similar to those of melted DNA without metal. However, difference spectra reveal some metal-specific perturbations at 1092 cm-1 (nPO2-), 1258 cm-1 (dC, dA), and 1668 cm-1 (nC==O, dNH2 dT, dG, dC). Increased spectral intensity could also be observed near 1335 cm-1 (dA, dG) for CaDNA. Optical densitometry, employed to detect DNA

  18. Chitosan oligosaccharide-Ca complex accelerates the depuration of cadmium from Chlamys ferrari

    NASA Astrophysics Data System (ADS)

    Huang, Guoqing; Sun, Jipeng; Wang, Dongfeng; Xu, Ying; Xu, Wei

    2012-06-01

    This study investigated the effect of a chitosan oligosaccharide-Ca complex (COS-Ca) on the depuration of cadmium (Cd) from Chlamys ferrari. After exposure to 0.5 mg L-1 CdCl2 for 3 or 7 d, the scallops were treated by COS-Ca prior to determination of Cd, calcium (Ca) and zinc (Zn) contents, Cd distribution in organs, malondialdehyde (MDA) content and antioxidant variables. Results showed that COS-Ca reduced Cd content in the viscera of the scallops, with highest Cd depuration rate (47%) observed on day 3. The COS-Ca concentration substantially affected Cd depuration, and the exposure to 8.75 mg L-1 COS-Ca led to significantly higher Cd depuration rate compared with those of lower COS-Ca concentrations (1.75, 3.5, 5.25, and 7.00 mg L-1). Distribution analysis of Cd in scallop organs indicated that COS-Ca significantly reduced Cd content in the kidney throughout the 5-d experiment, as well as in the gill during the early stage of Cd depuration. In addition, COS-Ca treatment decreased glutathione peroxidase (GSH-Px) activity and MDA content while increasing superoxide dismutase (SOD) and catalase (CAT) activities on different days. Our work suggested COS-Ca complex treatment as an effective method for acceleration of Cd depuration from Cd-contaminated bivalves.

  19. SUMMAR OF DISCUSSIONS OF USES OF THE ADVANCED LIGHT SOURCE (ALS)FOR EARTH SCIENCES RESEARCH: WORKSHOP REPORT OF THE ALS USERS'ASSOCIATION ANNUAL MEETING, LAWRENCE BERKELEY LABORATORY, BERKELEY,CA,JUNE 2-3, 1988

    SciTech Connect

    Dillard, J.; Wallenberg, H.; Perry, D.

    1988-09-01

    A workshop to discuss opportunities for research using the Advanced Light Source (ALS) was held as a part of the first annual ALS users meeting at the Berkeley Convention Center, Berkeley, California, June 2--3, 1988. The participants were from university and governmental laboratories, and some of those attending had had experience using synchrotron light sources. Because the Earth Science interests had not been voiced or considered in previous workshops or meetings of the ALS groups, it was the principal task of the group to explore the capabilities of the ALS appropriate to the Earth Sciences, to identify areas of research where the ALS would be of significant benefit, and to provide input regarding desired insertion devices. Discussions of synchrotron radiation phenomena and applications of synchrotron radiation in earth sciences have been highlighted in the literature and in a recent report of a workshop held at Argonne National Laboratory. A summary outline of some typical potential uses and the information to be gained from the use of synchrotron radiation is given. This is not an exhaustive list of earth sciences applications, but indicates the breadth of applications that can be addressed: (A) X-Ray Absorption Near Edge Structure (XANES) Spectroscopy (Oxidation state of elements; Coordination number of metal ions); (B) Extended X-Ray Absorption Fine Structure (EXAFS) Spectroscopy (Glasses and other disordered structures; Solutions; Gels -- silicates, aluminates; Clays -- swelling phenomena, intercation chemistry; Adsorption -- speciation, chemical reactions, kinetics; Polyhedral linkages -- Fe, Mn oxides); (C) Energy Dispersive X-Ray Diffraction (Mineral transformations vs temperature and pressure); (D) Small Angle Scattering (Precipitation phenomena); (E) X-Ray Microprobe (Element mapping). Comments and discussion at the ALS meeting identified the principal areas of interest for earth scientists as: adsorption phenomena; nucleation processes; gel structure

  20. Different responses of low grain-Cd-accumulating and high grain-Cd-accumulating rice cultivars to Cd stress.

    PubMed

    Wang, Feijuan; Wang, Min; Liu, Zhouping; Shi, Yan; Han, Tiqian; Ye, Yaoyao; Gong, Ning; Sun, Junwei; Zhu, Cheng

    2015-11-01

    Cadmium (Cd) is a major heavy metal pollutant which is highly toxic to plants and animals. The accumulation of Cd in rice grains is a major agricultural problem in regions with Cd pollution. A hydroponics experiment using low grain-Cd-accumulating rice (xiushui 11) and high grain-Cd-accumulating rice (xiushui 110) was carried out to characterize the different responses of rice cultivars to Cd stress. We found that xiushui 11 was more tolerant to Cd than xiushui 110, and xiushui 11 suffered less oxidative damage. Cell walls played an important role in limiting the amount of Cd that entered the protoplast, especially in xiushui 11. Cd stored in organelles as soluble fractions, leading to greater physiological stress of Cd detoxification. We found that Cd can disturb the ion homeostasis in rice roots because Cd(2+) and Ca(2+) may have a similar uptake route. Xiushui 11 had a faster root-to-shoot transport of Cd, and the expression level of OsPCR1 gene which was predicted related with Cd accumulation in rice was consist with the Cd transport of root-to-shoot in rice and maintain the greater Cd tolerance of xiushui 11. These results suggest there are different Cd detoxification and accumulation mechanisms in rice cultivars.

  1. Different responses of low grain-Cd-accumulating and high grain-Cd-accumulating rice cultivars to Cd stress.

    PubMed

    Wang, Feijuan; Wang, Min; Liu, Zhouping; Shi, Yan; Han, Tiqian; Ye, Yaoyao; Gong, Ning; Sun, Junwei; Zhu, Cheng

    2015-11-01

    Cadmium (Cd) is a major heavy metal pollutant which is highly toxic to plants and animals. The accumulation of Cd in rice grains is a major agricultural problem in regions with Cd pollution. A hydroponics experiment using low grain-Cd-accumulating rice (xiushui 11) and high grain-Cd-accumulating rice (xiushui 110) was carried out to characterize the different responses of rice cultivars to Cd stress. We found that xiushui 11 was more tolerant to Cd than xiushui 110, and xiushui 11 suffered less oxidative damage. Cell walls played an important role in limiting the amount of Cd that entered the protoplast, especially in xiushui 11. Cd stored in organelles as soluble fractions, leading to greater physiological stress of Cd detoxification. We found that Cd can disturb the ion homeostasis in rice roots because Cd(2+) and Ca(2+) may have a similar uptake route. Xiushui 11 had a faster root-to-shoot transport of Cd, and the expression level of OsPCR1 gene which was predicted related with Cd accumulation in rice was consist with the Cd transport of root-to-shoot in rice and maintain the greater Cd tolerance of xiushui 11. These results suggest there are different Cd detoxification and accumulation mechanisms in rice cultivars. PMID:26318143

  2. Lattice constant grading in the Al.sub.y Ca.sub.1-y As.sub.1-x Sb.sub.x alloy system

    DOEpatents

    Moon, Ronald L.

    1981-01-01

    Liquid phase epitaxy is employed to grow a lattice matched layer of GaAsSb on GaAs substrates through the compositional intermediary of the III-V alloy system AlGaAsSb which acts as a grading layer. The Al constituent reaches a peak atomic concentration of about 6% within the first 2.5.mu.m of the transition layer, then decreases smoothly to about 1% to obtain a lattice constant of 5.74 A. In the same interval the equilibrium concentration of Sb smoothly increases from 0 to about 9 atomic percent to form a surface on which a GaAsSb layer having the desired energy bandgap of 1.1 ev for one junction of an optimized dual junction photovoltaic device. The liquid phase epitaxy is accomplished with a step cooling procedure whereby dislocation defects are more uniformly distributed over the surface of the growing layer.

  3. Three-dimensional heat transfer effects during the growth of LiCaAlF 6 in a modified Bridgman furnace

    NASA Astrophysics Data System (ADS)

    Brandon, Simon; Derby, Jeffrey J.; Atherton, L. Jeffrey; Roberts, David H.; Vital, Russel L.

    1993-09-01

    A novel process modification, the simultaneous growth of three cylindrical Cr:LiCaAlf 6 (Cr:LiCAF) crystals grown from a common seed in a vertical Bridgman furnace of rectangular cross section, is assessed using computational modeling. The analysis employs the FIDAP finite-element package and accounts for three-dimensional, steady-state, conductive heat transfer throughout the system. The induction heating system is rigorously simulated via solution of Maxwell's equations. The implementation of realistic thermal boundary conditions and furnace details is shown to be important. Furnace design features are assessed through calculations, and simulations indicate expected growth conditions to be favorable. In addition, the validity of using ampoules containing "dummy" charges for experimental furnace characterization measurements is examined through test computations.

  4. 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)

    Partyka, Janusz; Sitarz, Maciej; Leśniak, Magdalena; Gasek, Katarzyna; Jeleń, Piotr

    2015-01-01

    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.

  5. A thermodynamic model for subsolidus equilibria in the system CaO-MgO-Al2O3-SiO2

    NASA Technical Reports Server (NTRS)

    Wood, B. J.; Holloway, J. R.

    1984-01-01

    It is shown that the high temperature enthalpy of solution data for pure phases and solid solutions in the CMAS system are, for 'gabbroic' and 'peridotitic' compositions, consistent with available phase equilibrium data for the MAS, CAS and CMAS systems. A refined set of values of thermodynamic properties for these phases and solid solutions is tabulated. The small differences between the new data set and that of Helgeson et al. (1978) arise from new data on heat capacity and enthalpy being incorporated. The important constraints applied and the major difficulties in fitting which arose are summarized.

  6. Thermally stable green Ba(3)Y(PO(4))3:Ce(3+),Tb(3+) and red Ca(3)Y(AlO)(3)(BO(3))4:Eu(3+) phosphors for white-light fluorescent lamps.

    PubMed

    Huang, Chien-Hao; Kuo, Te-Wen; Chen, Teng-Ming

    2011-01-01

    A class of thermal stable of green-emitting phosphors Ba(3)Y(PO(4))(3):Ce(3+),Tb(3+) (BYP:Ce(3+),Tb(3+)) and red-emitting phosphors Ca(3)Y(AlO)(3)(BO(3))(4):Eu(3+) (CYAB:Eu(3+)) for white-light fluorescent lamps were synthesized by high temperature solid-state reaction. We observed a decay of only 3% at 150 °C for BYP:0.25Ce3+,0.25Tb3+ (3% for LaPO4:Ce(3+),Tb(3+)), and a decay of 4% for CYAB:0.5Eu(3+) (7% for Y(2)O(3):Eu(3+), 24% for Y(2)O(2)S:Eu(3+)). The emission intensity of composition-optimized Ba(3)(Y(0.5)Ce(0.25)Tb(0.25))(PO(4))(3) is 70% of that of commercial LaPO(4):Ce(3+),Tb(3+) phosphors, and the CIE chromaticity coordinates are found to be (0.323, 0.534). The emission intensity of Ca(3)(Y(0.5)Eu(0.5))(AlO)(3)(BO(3))(4) is 70% and 83% of those of Y(2)O(3):Eu(3+) and Y(2)O(2)S:Eu(3+) phosphors, respectively, and the CIE chromaticity coordinates are redder (0.652, 0.342) than those of Y(2)O(3):Eu(3+) (0.645, 0.347) and Y(2)O(2)S:Eu(3+) (0.647, 0.343). A white-light fluorescent lamp is fabricated using composition-optimized Ba(3)(Y(0.5)Ce(0.25)Tb(0.25))(PO(4))(3) and Ca(3)(Y(0.5)Eu(0.5))(AlO)(3)(BO(3))(4) phosphors and matching blue-emitting phosphors. The results indicate that the quality of the brightness and color reproduction is suitable for application in shortwave UV fluorescent lamps. The white-light fluorescent lamp displays CIE chromaticity coordinates of x = 0.33, y = 0.35, a warm white light with a correlated color temperature of 5646 K, and a color-rendering index of Ra = 70.

  7. Uptake of Al, As, Cr, Cd, Cu, Fe, Mn, Ni, Pb, Sr, and Zn in native wheatgrasses, wildryes, and bluegrass on three metal-contaminated soils from Montana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One of the biggest challenges to successfully phytoremediate contaminated mineland soils is the identification of native plants that possess a broad adaptation to ecological sites and either exclude or uptake heavy metals of interest. This study evaluated forage concentrations of aluminum (Al), ars...

  8. Study of damage induced by room-temperature Al ion implantation in Hg{sub 0.8}Cd{sub 0.2}Te by x-ray diffuse scattering

    SciTech Connect

    Renault, P.O.; Declemy, A.; Leveque, P.; Fayoux, C.; Bessiere, M.; Lefebvre, S.; Corbel, C.; Baroux, L.

    1997-07-01

    Ion-implantation is a widely used doping technique in II{endash}VI semiconductors. Nevertheless, ion-implantation damage has to be better understood to properly control this process. In order to investigate the implantation-induced defects in such compounds, room-temperature implantations of 320 keV Al ions have been performed on crystalline samples of [111] Hg{sub 1{minus}x}Cd{sub x}Te (x{approx}20{percent}) for doses ranging from 10{sup 13} to 10{sup 15}cm{sup {minus}2}. We report the first measurements of x-ray diffuse scattering close to different Bragg reflections on such as-implanted samples. The evolution of the diffuse intensity as a function of the dose has been observed. The defect-induced diffuse intensity arises mainly from interstitial dislocation loops. Nevertheless, vacancy loops are observed above 3{times}10{sup 14}Al/cm{sup 2}. The mean radius of the dislocation loops increases in size by three to four times when the dose rises from 10{sup 13} to 10{sup 15}cm{sup {minus}2}. Finally, the saturation of point defects has been observed independently of their clustering at about 5{times}10{sup 13}Al/cm{sup 2}, that is in the same range as the saturation dose of the sheet electron concentration. {copyright} {ital 1997 American Institute of Physics.}

  9. An investigation of CaO-MgO-Al[sub 2]O[sub 3]-SiO[sub 2] liquids by nuclear magnetic resonance spectroscopy, vibrational spectroscopy, and ion dynamics simulation

    SciTech Connect

    Poe, B.T.

    1993-01-01

    A multi-directional approach has been taken in order to investigate the structural and dynamic properties associated with liquid phases in the system CaO-MgO-Al[sub 2]O[sub 3]-SiO[sub 2] (CMAS). Using a newly developed high temperature [sup 27]Al Nuclear Magnetic Resonance (NMR) spectroscopic technique, which involves simultaneously levitating and heating the sample with a CO[sub 2] laser, direct structural and dynamic information on refractory aluminate and aluminosilicate liquids has been obtained at temperature of 2000 K and above. From this technique, measured isotropic chemical shifts and NMR linewidths of the liquids exhibit systematic trends with variations in composition which can be associated with the static and relaxation behavior of the structural environment about aluminum. Structural information of the liquids is time-averaged due to the rapid motional averaging characteristic of these liquids at the timescale of the NMR experiment. Comparison of these results with those of corresponding glasses both from solid state NMR and vibrational spectroscopic experiments allows for a more detailed interpretation of the structural makeup of these liquids. Combined with results and next-nearest-neighbor environments allows for a more quantitative estimation of the melts investigated suggest greater proportions of high coordinate aluminum species (AlO[sub 5] and AlO[sub 6] units) compared to existing data compiled for corresponding glasses. Finally, in-situ high temperature Raman spectra have been obtained which show direct experimental evidence for the presence of distinct molecular species in these refractory liquids, and also indicate structural changes as a function to temperature.

  10. A vibrational spectroscopic study of the phosphate mineral whiteite CaMn(++)Mg2Al2(PO4)4(OH)2·8(H2O).

    PubMed

    Frost, Ray L; Scholz, Ricardo; López, Andrés; Xi, Yunfei

    2014-04-24

    Vibrational spectroscopy enables subtle details of the molecular structure of whiteite to be determined. Single crystals of a pure phase from a Brazilian pegmatite were used. The infrared and Raman spectroscopy were applied to compare the molecular structure of whiteite with that of other phosphate minerals. The Raman spectrum of whiteite shows an intense band at 972 cm(-1) assigned to the ν1PO4(3-) symmetric stretching vibrations. The low intensity Raman bands at 1076 and 1173 cm(-1) are assigned to the ν3PO4(3-) antisymmetric stretching modes. The Raman bands at 1266, 1334 and 1368 cm(-1) are assigned to AlOH deformation modes. The infrared band at 967 cm(-1) is ascribed to the PO4(3-)ν1 symmetric stretching vibrational mode. The infrared bands at 1024, 1072, 1089 and 1126 cm(-1) are attributed to the PO4(3-)ν3 antisymmetric stretching vibrations. Raman bands at 553, 571 and 586 cm(-1) are assigned to the ν4 out of plane bending modes of the PO4(3-) unit. Raman bands at 432, 457, 479 and 500 cm(-1) are attributed to the ν2 PO4 and H2PO4 bending modes. In the 2600 to 3800 cm(-1) spectral range, Raman bands for whiteite are found 3426, 3496 and 3552 cm(-1) are assigned to AlOH stretching vibrations. Broad infrared bands are also found at 3186 cm(-1). Raman bands at 2939 and 3220 cm(-1) are assigned to water stretching vibrations. Raman spectroscopy complimented with infrared spectroscopy has enabled aspects of the structure of whiteite to be ascertained and compared with that of other phosphate minerals.

  11. A vibrational spectroscopic study of the phosphate mineral whiteite CaMn(++)Mg2Al2(PO4)4(OH)2·8(H2O).

    PubMed

    Frost, Ray L; Scholz, Ricardo; López, Andrés; Xi, Yunfei

    2014-04-24

    Vibrational spectroscopy enables subtle details of the molecular structure of whiteite to be determined. Single crystals of a pure phase from a Brazilian pegmatite were used. The infrared and Raman spectroscopy were applied to compare the molecular structure of whiteite with that of other phosphate minerals. The Raman spectrum of whiteite shows an intense band at 972 cm(-1) assigned to the ν1PO4(3-) symmetric stretching vibrations. The low intensity Raman bands at 1076 and 1173 cm(-1) are assigned to the ν3PO4(3-) antisymmetric stretching modes. The Raman bands at 1266, 1334 and 1368 cm(-1) are assigned to AlOH deformation modes. The infrared band at 967 cm(-1) is ascribed to the PO4(3-)ν1 symmetric stretching vibrational mode. The infrared bands at 1024, 1072, 1089 and 1126 cm(-1) are attributed to the PO4(3-)ν3 antisymmetric stretching vibrations. Raman bands at 553, 571 and 586 cm(-1) are assigned to the ν4 out of plane bending modes of the PO4(3-) unit. Raman bands at 432, 457, 479 and 500 cm(-1) are attributed to the ν2 PO4 and H2PO4 bending modes. In the 2600 to 3800 cm(-1) spectral range, Raman bands for whiteite are found 3426, 3496 and 3552 cm(-1) are assigned to AlOH stretching vibrations. Broad infrared bands are also found at 3186 cm(-1). Raman bands at 2939 and 3220 cm(-1) are assigned to water stretching vibrations. Raman spectroscopy complimented with infrared spectroscopy has enabled aspects of the structure of whiteite to be ascertained and compared with that of other phosphate minerals. PMID:24491665

  12. Sulfide Capacities of CaO-Al2O3-SiO2 Slags in the Temperature Range 1673 K to 1773 K (1400 °C to 1500 °C)

    NASA Astrophysics Data System (ADS)

    Taniguchi, Yoshinori; Wang, Lijun; Sano, Nobuo; Seetharaman, Seshadri

    2012-06-01

    With a goal to estimate the sulfide capacities of slags used in the pretreatment of hot metal, the sulfide capacities of CaO-Al2O3-SiO2 slags were measured at 1673 K to 1773 K (1400 °C to 1500 °C). The gas-slag equilibrium technique has been used for this measurement. From the results obtained, it was found that the temperature dependence of the sulfide capacity of this slag is independent of the slag compositions. Therefore, a new empirical model based on optical basicity for sulfide capacity estimation of this slag was developed using the measured values of the current work and literature. With the use of the new model, the isosulfide capacity curves at 1673 K (1400 °C) were mapped.

  13. Phase Relations and Elemental Distribution among Co-Existing Phases in the Ceramics of the Pseudobinary System CaZrTi{sub 2}O{sub 7}-CeAlO{sub 3}

    SciTech Connect

    Mikhailenko, N.S.; Stefanovsky, S.V.; Lapina, M.I.

    2006-07-01

    Ceramics formally related to a pseudo-binary system CaZrTi{sub 2}O{sub 7}-CeAlO{sub 3} being important for design of matrices for immobilization of a rare-earth - actinide fraction of high level waste were synthesized by cold pressing and sintering at temperatures of 1400, 1450 and 1500 deg. C. It has been shown that the target zirconolite and perovskite structure phases as well as cerium and zirconium dioxide based cubic phases were formed. Content of the latter phases in the ceramics increases significantly with increase of sintering temperature to 1500 deg. C and they are capable to accumulate up to 77% CeO{sub 2} of total amount introduced. (authors)

  14. Thermodynamic tabulations for selected phases in the system CaO-Al2O3-SiO2-H2 at 101.325 kPa (1 atm) between 273.15 and 1800 K

    USGS Publications Warehouse

    Haas, John L.; Robinson, Glipin R.; Hemingway, Bruch S.

    1981-01-01

    The standard thermodynamic properties of phases in the lime‐alumina‐silica‐ water system between 273.15 and 1800 K at 101.325 kPa (1 atm) were evalated from published experimental data. Phases included in the compilation are boehmite, diaspore, gibbsite, kaolinite, dickite, halloysite, andalusite, kyanite, sillimanite, Ca‐Al cliniopyroxene, anorthite, gehlenite, grossular, prehnite, zoisite, margarite, wollastonite, cyclowollastonite ( = pseudowollastonite), larnite, Ca olivine, hatrurite, and rankinite. The properties include heat capacity, entropy, relative enthalpy, and the Gibbs energy function of the phases and the enthalpies, Gibbs energies, and equilibrium constants for formation both from the elements and the oxides. Tabulated values are given at 50 K intervals with the 2‐sigma confidence limit at 250 K intervals. Summaries for each phase give the temperature‐ dependent functions for heat capacity, entropy, and relative enthalpy and the experimental data used in the final evaluation.

  15. CaO-MgO-Al2O3-SiO2 (CMAS) corrosion of Gd2Zr2O7 and Sm2Zr2O7

    DOE PAGES

    Wang, Honglong; Bakal, Ahmet; Zhang, Xingxing; Tarwater, Emily; Sheng, Zhizhi; Fergus, Jeffrey W.

    2016-08-08

    Ceramic thermal barrier coatings are applied to superalloys used in gas turbine engineering to increase the operating temperature and the energy conversion efficiency. However, dust consisting of CaO-MgO-Al2O3-SiO2 (CMAS) from the air can be injected into the engines and corrode the thermal barrier coatings. Lanthanide zirconates are promising materials in thermal barrier coatings due to their low thermal conductivities, good phase stability and good corrosion resistance. However, the corrosion resistance mechanism of CMAS on lanthanide zirconates is still not clearly understood. In this work, the corrosion mechanism of Gd2Zr2O7 and Sm2Zr2O7 in CMAS is studied. Here, the results show thatmore » the CMAS can easily react with lanthanide zirconate thermal barrier coatings to form a dense layer, which can resist further corrosion« less

  16. Elucidating the mechanism behind the stabilization of multi-charged metal cations in water: A case study of the electronic states of microhydrated Mg2+, Ca2+ and Al3+”

    SciTech Connect

    Miliordos, Evangelos; Xantheas, Sotiris S.

    2014-04-21

    Metal atoms typically have second and higher ionization potentials (IPs) that are larger than the IP of water, resulting in the Coulombic explosion of the first few [M(H2O)n]+q (q ≥ 2) clusters as the M+ + (H2O)n + or MOH+ + H3O+(H2O)n energy levels are energetically more stable than the M2+ + (H2O)n ones for small n. We present a theoretical analysis of the various electronic states correlating with the above channels that are involved in the sequential hydration of the Ca2+, Mg2+ and Al3+ cations with up to six water molecules that, for the first time, quantifies their relative shift with the degree of solvation accounting for the observed stabilization of those multi-charged metal cations in an aqueous solution. *

  17. FAST TRACK COMMUNICATION: Field dependence of temperature induced irreversible transformations of magnetic phases in Pr0.5Ca0.5Mn0.975Al0.025O3 crystalline oxide

    NASA Astrophysics Data System (ADS)

    Lakhani, Archana; Kushwaha, Pallavi; Rawat, R.; Kumar, Kranti; Banerjee, A.; Chaddah, P.

    2010-01-01

    Glass-like arrest has recently been reported in various magnetic materials. As in structural glasses, the kinetics of a first order transformation is arrested while retaining the higher entropy phase as a non-ergodic state. We show visual mesoscopic evidence of the irreversible transformation of the arrested antiferromagnetic-insulating phase in Pr0.5Ca0.5Mn0.975Al0.025O3 to its equilibrium ferromagnetic-metallic phase with an isothermal increase of magnetic field, similar to its iso-field transformation on warming. The magnetic field dependence of the non-equilibrium to equilibrium transformation temperature is shown to be governed by Le Chatelier's principle.

  18. Field dependence of temperature induced irreversible transformations of magnetic phases in Pr(0.5)Ca(0.5)Mn(0.975)Al(0.025)O(3) crystalline oxide.

    PubMed

    Lakhani, Archana; Kushwaha, Pallavi; Rawat, R; Kumar, Kranti; Banerjee, A; Chaddah, P

    2010-01-27

    Glass-like arrest has recently been reported in various magnetic materials. As in structural glasses, the kinetics of a first order transformation is arrested while retaining the higher entropy phase as a non-ergodic state. We show visual mesoscopic evidence of the irreversible transformation of the arrested antiferromagnetic-insulating phase in Pr(0.5)Ca(0.5)Mn(0.975)Al(0.025)O(3) to its equilibrium ferromagnetic-metallic phase with an isothermal increase of magnetic field, similar to its iso-field transformation on warming. The magnetic field dependence of the non-equilibrium to equilibrium transformation temperature is shown to be governed by Le Chatelier's principle. PMID:21386273

  19. Crystallization, densification and dielectric properties of CaO–MgO–Al{sub 2}O{sub 3}–SiO{sub 2} glass with ZrO{sub 2} as nucleating agent

    SciTech Connect

    Hsiang, Hsing-I; Yung, Shi-Wen; Wang, Chung-Ching

    2014-12-15

    SEM micrographs for the pure CaO–MgO–Al{sub 2}O{sub 3}–SiO{sub 2} glass sintered at 850–1000 °C (a) 850 °C, (b) 900 °C, (c) 950 °C, (d) 1000 °C. - Highlights: • ZrO{sub 2} effects on the crystallization of LTCC glass system were investigated. • ZrO{sub 2} effects on the dielectric properties of LTCC glass system were investigated. • LTCC with a dielectric constant of 6.65 and a low dielectric loss can be obtained. - Abstract: The zirconium oxide effects on the crystallization and dielectric properties of CaO–MgO–Al{sub 2}O{sub 3}–SiO{sub 2} (CMAS) glass were investigated. The results showed that phyllosiloxide and anorthite crystallites were observed in sequence during sintering. For glass added with 8 wt% ZrO{sub 2}, homogeneously dispersed tetragonal ZrO{sub 2} crystallites were observed at 850 °C. The as-prepared CMAS glass–ceramics exhibited a dielectric constant of about 6–7 and a dielectric loss below 0.005 at 100 MHz. The dielectric properties of CMAS glass with 8 wt% ZrO{sub 2} sintered at 850 °C show a low dielectric constant of 6.65 and a dielectric loss tangent of about 2.5 × 10{sup −3}, which provides a promising candidate for LTCC applications.

  20. Esperanzaite, NaCa2Al2(As5+O4)2F4(OH)*2H2O, a new mineral species from the La Esperanza mine, Mexico: descriptive mineralogy and atomic arrangement

    USGS Publications Warehouse

    Foord, E.E.; Hughes, J.M.; Cureton, F.; Maxwell, C.H.; Falster, A.U.; Sommer, A.J.; Hlava, P.F.

    1999-01-01

    Esperanzaite, ideally NaCa2Al2(As5+O4)2F4(OH)??2H2O, Z = 2, is a new mineral species from the La Esperanza mine, Durango State, Mexico. The mineral occurs as blue-green botryoidal crystalline masses on rhyolite, with separate spheres up to 1.5 mm in diameter. The Mohs hardness is 4 1/2 , and the specific gravity, 3.24 (obs.) and 3.36(3) (calc.). Optical properties were measured in 589 nm light. Esperanzaite is biaxial (-), X = Y = Z = colorless, ?? 1.580(1), ?? 1.588(1), and ?? 1.593(1); 2V(obs) is 74(1)??and 2V(calc) is 76.3??. The dispersion is medium, r < v, and the optic axes are oriented according to a ?? Z = +50.5??, b = Y, c ?? X = +35??. The strongest five X-ray-diffraction maxima in the powder pattern [d in A??(I)(hkl)] are: 2.966(100)(131, 311, 031), 3.527(90)(220), 2.700(90)(221,002,040), 5.364(80)(001,020) and 4.796(80)(011). Esperanzaite is monoclinic, a 9.687(5), b 10.7379(6), c 5.5523(7) A??, ?? 105.32(1)??, space group P21/m. The atomic arrangement of esperanzaite was solved by direct methods and Fourier analysis (R = 0.032). The Fundamental Building Block (FBB) is formed of [001] stacks of heteropolyhedral tetramers; the tetramers are formed of two arsenate tetrahedra and two Al octahedra, corner-linked in four-member rings. The FBBs are linked by irregular Na??5 and Ca??8 polyhedra.

  1. A modern, guano-related occurrence of foggite, CaAl(PO4)(OH)2 · H2O and churchite-(Y), YPO4 · 2H2O in Cioclovina Cave, Romania

    NASA Astrophysics Data System (ADS)

    Onac, B. P.; Ettinger, K.; Kearns, J.; Balasz, I. I.

    2005-12-01

    This study reports foggite and churchite-(Y) from two spatially separate locations in the guano-related phosphate deposit from the Cioclovina Cave, Romania. Optical microscope observations, powder X-ray diffraction, electron microprobe analyses, and FTIR were used in the analysis of the two minerals. The chemical composition of foggite was determined to be Ca0.925(Al0.91Fe2+0.016)Σ0.926(P0.991Si0.043)Σ1.034O3.74(OH)2.26 · H2O and churchite-(Y) [(Y0.830Dy0.043Er0.033Gd0.029Yb0.022)Σ0.957Ca0.009]P1.023O4.00 · 2H2O. Chemical analyses of Cioclovina churchite-(Y) clearly revealed enrichment in lanthanides of even atomic number. The refined unit-cell parameters are for foggite (orthorhombic) a = 9.264(1) Å, b = 21.334(8) Å, c = 5.197(7) Å, and V = 1027.13(8) Å3 (Z = 8); for churchite-(Y) (monoclinic): a = 5.578(8) Å, b = 15.013(6) Å, c = 6.277(8) Å, β = 117.94(4)°, and V = 464.38(5) Å3 (Z = 4). FTIR spectrum of churchite-(Y) exhibits all the bands assigned to the vibrations of PO4, OH, and water groups.

  2. Effect of surface chemistries and characteristics of Ti6Al4V on the Ca and P adsorption and ion dissolution in Hank's ethylene diamine tetra-acetic acid solution.

    PubMed

    Chang, E; Lee, T M

    2002-07-01

    This study examined the influence of chemistries and surface characteristics of Ti6Al4V on the adsorption of Ca and P species and ion dissolution behavior of the material exposed in Hank's solution with 8.0 mM ethylene diamine tetra-acetic acid at 37 degrees C. The variation of chemistries of the alloy and nano-surface characteristics (chemistries of nano-surface oxides, amphoteric OH group adsorbed on oxides, and oxide thickness) was effected by surface modification and three passivation methods (34% nitric acid passivation. 400 degrees C heated in air, and aged in 100 degrees C water). X-ray photoelectron spectroscopy and Auger electron spectroscopy were used for surface analyses. The chemistries of nano-surface oxides in a range studied should not change the capability of Ca and P adsorption. Nor is the capability affected significantly by amphoteric OH group and oxide thickness. However, passivations influence the surface oxide thickness and the early stage ion dissolution rate of the alloy. The rate-limiting step of the rate can be best explained by metal-ion transport through the oxide film, rather than hydrolysis of the film. Variation of the chemistries of titanium alloy alters the electromotive force potential of the metal, thereby affecting the corrosion and ion dissolution rate.

  3. Bulk modulus and specific heat of B-site doped (La0.3Pr0.7)0.65Ca0.35Mn1-xBxO3 (B=Fe, Cr, Ru, Al, Ga)

    NASA Astrophysics Data System (ADS)

    Srivastava, Archana; Thakur, Rasna; Gaur, N. K.

    2014-04-01

    Specific heat (Cp) thermal expansion (α) and Bulk modulus (BT) of lightly doped Rare Earth manganites (La0.3Pr0.7)0.65Ca0.35Mn1-xBxO3 (B3+ = Fe3+,Cr3+,Ga3+,Al3+,Ru4+); (0.3Ca0.35Mn0.97Fe0.03O3 as a function of temperature (10K≤T≤ 200K) is found to be in agreement with the published data. The trend of variation of Debye temperature with B-site cationic radius is predicted probably for the first time for the B-site doped rare earth manganites.

  4. Cross sections for the production of residual nuclides by low- and medium-energy protons from the target elements C, N, O, Mg, Al, Si, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Sr, Y, Zr, Nb, Ba and Au

    NASA Astrophysics Data System (ADS)

    Michel, R.; Bodemann, R.; Busemann, H.; Daunke, R.; Gloris, M.; Lange, H.-J.; Klug, B.; Krins, A.; Leya, I.; Lüpke, M.; Neumann, S.; Reinhardt, H.; Schnatz-Büttgen, M.; Herpers, U.; Schiekel, Th.; Sudbrock, F.; Holmqvist, B.; Condé, H.; Malmborg, P.; Suter, M.; Dittrich-Hannen, B.; Kubik, P.-W.; Synal, H.-A.; Filges, D.

    1997-07-01

    Cross sections for residual nuclide production by p-induced reactions were measured from thresholds up to 2.6 GeV using accelerators at CERN/Geneve, IPN/Orsay, KFA/Jülich, LANL/Los Alamos, LNS/Saclay, PSI/Villigen, TSL/Uppsala, LUC/Louvain La Neuve. The target elements C, N, O, Mg, Al, Si, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Sr, Y, Zr, Nb, Ba and Au were investigated. Residual nuclides were measured by X- and γ-spectrometry and by Accelerator Mass Spectrometry (AMS). The measured cross sections were corrected for interfering secondary particles in experiments with primary proton energies above 200 MeV. Our consistent database covers presently ca 550 nuclear reactions and contains nearly 15000 individual cross sections of which about 10000 are reported here for the first time. They provide a basis for model calculations of the production of cosmogenic nuclides in extraterrestrial matter by solar and galactic cosmic ray protons. They are of importance for many other applications in which medium energy nuclear reactions have to be considered ranging from astrophysics over space and environmental sciences to accelerator technology and accelerator-based nuclear waste transmutation and energy amplification. The experimental data are compared with theoretical ones based on calculations using an INC/E model in form of the HETC/KFA2 code and on the hybrid model of preequilibrium reactions in form of the AREL code.>

  5. Electrophoretic deposition of porous CaO-MgO-SiO2 glass-ceramic coatings with B2O3 as additive on Ti-6Al-4V alloy.

    PubMed

    Zhang, Wei; Chen, Xianchun; Liao, Xiaoming; Huang, Zhongbing; Dan, Xiuli; Yin, Guangfu

    2011-10-01

    The sub-micron glass-ceramic powders in CaO-MgO-SiO(2) system with 10 wt% B(2)O(3) additive were synthesized by sol-gel process. Then bioactive porous CaO-MgO-SiO(2) glass-ceramic coatings on Ti-6Al-4V alloy substrates were fabricated using electrophoretic deposition (EPD) technique. After being calcined at 850°C, the above coatings with thickness of 10-150 μm were uniform and crack-free, possessing porous structure with sub-micron and micron size connected pores. Ethanol was employed as the most suitable solvent to prepare the suspension for EPD. The coating porous appearance and porosity distribution could be controlled by adjusting the suspension concentration, applied voltage and deposition time. The heat-treated coatings possessed high crystalline and was mainly composed of diopside, akermanite, merwinite, calcium silicate and calcium borate silicate. Bonelike apatite was formed on the coatings after 7 days of soaking in simulated body fluid (SBF). The bonding strength of the coatings was needed to be further improved.

  6. Crystallization Kinetics and Mechanism of CaO-Al2O3-Based Mold Flux for Casting High-Aluminum TRIP Steels

    NASA Astrophysics Data System (ADS)

    Shi, Cheng-Bin; Seo, Myung-Duk; Wang, Hui; Cho, Jung-Wook; Kim, Seon-Hyo

    2015-02-01

    Non-isothermal crystallization of the newly developed lime-alumina-based mold fluxes was investigated using differential scanning calorimetry. The crystallization kinetic parameters were determined by Ozawa equation, the combined Avrami-Ozawa equation, and the differential iso-conversional method of Friedman. It was found that Ozawa method failed to describe the non-isothermal crystallization behavior of the mold fluxes. The Avrami exponent determined by the combined Avrami-Ozawa equation indicates that the crystallization of cuspidine occurs through bulk nucleation and reaction-controlled three-dimensional growth, and then transforms to reaction-controlled two-dimensional growth at the crystallization later stage in lime-alumina-based mold fluxes with higher B2O3 content. For the mold fluxes with lower B2O3 content (10.8 mass pct), the crystallization of cuspidine is bulk nucleation and reaction-controlled two-dimensional growth at the crystallization primary stage followed by a diffusion-controlled two-dimensional growth process. The crystallization of CaF2 in mold flux originates from bulk nucleation and diffusion-controlled three-dimensional growth, which then transforms to two-dimensional growth. FE-SEM observations support these kinetic analysis results. The effective activation energy for cuspidine crystallization in the mold flux with higher B2O3 and Na2O contents increases as the crystallization progresses, and then decreases at the relative degree of crystallinity greater than 60 pct. The transition point of this trend approximately corresponds to the relative degree of crystallinity at which the crystallization mode of cuspidine transforms. For the mold fluxes with lower B2O3 and Na2O contents, the effective activation energy for cuspidine formation varies monotonically with the increase in the relative degree of crystallinity.

  7. Crystallization Kinetics and Mechanism of CaO-Al2O3-Based Mold Flux for Casting High-Aluminum TRIP Steels

    NASA Astrophysics Data System (ADS)

    Shi, Cheng-Bin; Seo, Myung-Duk; Wang, Hui; Cho, Jung-Wook; Kim, Seon-Hyo

    2014-09-01

    Non-isothermal crystallization of the newly developed lime-alumina-based mold fluxes was investigated using differential scanning calorimetry. The crystallization kinetic parameters were determined by Ozawa equation, the combined Avrami-Ozawa equation, and the differential iso-conversional method of Friedman. It was found that Ozawa method failed to describe the non-isothermal crystallization behavior of the mold fluxes. The Avrami exponent determined by the combined Avrami-Ozawa equation indicates that the crystallization of cuspidine occurs through bulk nucleation and reaction-controlled three-dimensional growth, and then transforms to reaction-controlled two-dimensional growth at the crystallization later stage in lime-alumina-based mold fluxes with higher B2O3 content. For the mold fluxes with lower B2O3 content (10.8 mass pct), the crystallization of cuspidine is bulk nucleation and reaction-controlled two-dimensional growth at the crystallization primary stage followed by a diffusion-controlled two-dimensional growth process. The crystallization of CaF2 in mold flux originates from bulk nucleation and diffusion-controlled three-dimensional growth, which then transforms to two-dimensional growth. FE-SEM observations support these kinetic analysis results. The effective activation energy for cuspidine crystallization in the mold flux with higher B2O3 and Na2O contents increases as the crystallization progresses, and then decreases at the relative degree of crystallinity greater than 60 pct. The transition point of this trend approximately corresponds to the relative degree of crystallinity at which the crystallization mode of cuspidine transforms. For the mold fluxes with lower B2O3 and Na2O contents, the effective activation energy for cuspidine formation varies monotonically with the increase in the relative degree of crystallinity.

  8. Raman and infrared spectroscopy study on structure and microstructure of glass-ceramic materials from SiO2-Al2O3-Na2O-K2O-CaO system modified by variable molar ratio of SiO2/Al2O3.

    PubMed

    Partyka, Janusz; Leśniak, Magdalena

    2016-01-01

    This paper is focused on the effect of the molar ratio of SiO2/Al2O3 on the microstructure and structure of the internal aluminium-silicon-oxide lattice of the glass-ceramic materials from the SiO2-Al2O3-Na2O-K2O-CaO system. In order to examine the real composition of the obtained samples, a chemical analysis was performed. Following the heat-treatment procedure, pseudowollastonite, anorthite and the vitreous phase were identified. In order to determine the microstructure, research using the scanning electron microscope (SEM) with EDS was done. For the inner structural study, X-ray diffraction (XRD), Raman spectroscopy as well as MIR and FIR spectroscopy were performed.

  9. Simultaneous measurement of the trace elements Al, As, B, Be, Cd, Co, Cu, Fe, Li, Mn, Mo, Ni, Rb, Se, Sr, and Zn in human serum and their reference ranges by ICP-MS.

    PubMed

    Forrer, R; Gautschi, K; Lutz, H

    2001-04-01

    The goal of this article was to establish reference ranges of the concentration of trace elements in human serum and to compare these results with those reported by other authors. We describe the sample preparation and measurement conditions that allow the rapid, precise, and accurate determination of Al, As, B, Be, Cd, Co, Cu, Fe, Li, Mn, Mo, Ni, Rb, Se, Sr, and Zn in human serum samples (n = 110) by inductively coupled plasma-mass spectrometry (ICP-MS). Accuracy and precision were determined by analyzing three reconstituted reference serum samples by comparison with other methods and by the standard addition procedure. The advantages of the ICP-MS method include short time of analysis of the elements mentioned, low detection limit, high precision, and high accuracy. Disadventages include a high risk of contamination due to the presence of some of the elements of interest in the environment, the relatively delicate sample handling, and the high cost of the equipment.

  10. A Sulfide Capacity Prediction Model of CaO-SiO2-MgO-FeO-MnO-Al2O3 Slags during the LF Refining Process Based on the Ion and Molecule Coexistence Theory

    NASA Astrophysics Data System (ADS)

    Yang, Xue-Min; Zhang, Meng; Shi, Cheng-Bin; Chai, Guo-Ming; Zhang, Jian

    2012-04-01

    A sulfide capacity prediction model of CaO-SiO2-MgO-FeO-MnO-Al2O3 ladle furnace (LF) refining slags has been developed based on the ion and molecule coexistence theory (IMCT). The predicted sulfide capacity of the LF refining slags has better accuracy than the measured sulfide capacity of the slags at the middle and final stages during the LF refining process. Increasing slag binary basicity, optical basicity, and the Mannesmann index can lead to an increase of the predicted sulfide capacity for the LF refining slags as well as to an increase of the sulfur distribution ratio between the slags and molten steel at the middle and final stages during the LF refining process. The calculated equilibrium mole numbers, mass action concentrations of structural units or ion couples, rather than mass percentages of components, are recommended to represent the slag composition for correlating with the sulfide capacity of the slags. The developed sulfide capacity IMCT model can calculate not only the total sulfide capacity of the slags but also the respective sulfide capacity of free CaO, MgO, FeO, and MnO in the slags. The comprehensive contribution of the combined ion couples (Ca2+ + O2-) and (Mn2+ + O2-) on the desulfurization reactions accounts for 96.23 pct; meanwhile, the average contribution of the ion couple (Fe2+ + O2-) and (Mg2+ + O2-) only has a negligible contribution as 3.13 pct and 0.25 pct during the LF refining process, respectively. The oxygen activity of bulk molten steel in LF is controlled by the [Al]-[O] equilibrium, and the oxygen activity of molten steel at the slag-metal interface is controlled by the (FeO)-[O] equilibrium. The ratio of the oxygen activity of molten steel at the slag-metal interface to the oxygen activity of bulk molten steel will decrease from 37 to 5 at the initial stage, and further decrease from 28 to 4 at the middle stage, but will maintain at a reliable constant as 5 to 14 at the final stage during the LF refining process. The

  11. Infrared and Raman spectroscopic characterisation of the sulphate mineral creedite - Ca3Al2SO4(F,OH)·2H2O - and in comparison with the alums

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Xi, Yunfei; Scholz, Ricardo; López, Andrés; Granja, Amanda

    2013-05-01

    The mineral creedite is a fluorinated hydroxy hydrated sulphate of aluminium and calcium of formula Ca3Al2SO4(F,OH)·2H2O. The mineral has been studied by a combination of electron probe analysis to determine the molecular formula of the mineral and the structure assessed by vibrational spectroscopy. The spectroscopy of creedite may be compared with that of the alums. The Raman spectrum of creedite is characterised by an intense sharp band at 986 cm-1 assigned to the SO42- ν1 (Ag) symmetric stretching mode. Multiple bands of creedite in the antisymmetric stretching region support the concept of a reduction in symmetry of the sulphate anion. Multiple bands are also observed in the bending region with the three bands at 601, 629 and 663 cm-1 assigned to the SO42- ν4 (Ag) bending modes. The observation of multiple bands at 440, 457 and 483 cm-1 attributed to the SO42- ν2 (Bg) bending modes supports the concept that the symmetry of the sulphate is reduced by coordination to the water bonded to the Al3+ in the creedite structure. The splitting of the ν2, ν3 and ν4 modes is attributed to the reduction of symmetry of the SO4 and it is proposed that the sulphate coordinates to water in the hydrated aluminium in bidentate chelation.

  12. Infrared and Raman spectroscopic characterisation of the sulphate mineral creedite--Ca3Al2SO4(F,OH)·2H2O--and in comparison with the alums.

    PubMed

    Frost, Ray L; Xi, Yunfei; Scholz, Ricardo; López, Andrés; Granja, Amanda

    2013-05-15

    The mineral creedite is a fluorinated hydroxy hydrated sulphate of aluminium and calcium of formula Ca3Al2SO4(F,OH)·2H2O. The mineral has been studied by a combination of electron probe analysis to determine the molecular formula of the mineral and the structure assessed by vibrational spectroscopy. The spectroscopy of creedite may be compared with that of the alums. The Raman spectrum of creedite is characterised by an intense sharp band at 986 cm(-1) assigned to the SO4(2)- ν1 (Ag) symmetric stretching mode. Multiple bands of creedite in the antisymmetric stretching region support the concept of a reduction in symmetry of the sulphate anion. Multiple bands are also observed in the bending region with the three bands at 601, 629 and 663 cm(-1) assigned to the SO4(2)- ν4 (Ag) bending modes. The observation of multiple bands at 440, 457 and 483 cm(-1) attributed to the SO4(2)- ν2 (Bg) bending modes supports the concept that the symmetry of the sulphate is reduced by coordination to the water bonded to the Al(3+) in the creedite structure. The splitting of the ν2, ν3 and ν4 modes is attributed to the reduction of symmetry of the SO4 and it is proposed that the sulphate coordinates to water in the hydrated aluminium in bidentate chelation.

  13. Thermodynamic modeling of non-ideal mineral-fluid equilibria in the system Si-Al-Fe-Mg-Ca-Na-K-H-O-Cl at elevated temperatures and pressures: Implications for hydrothermal mass transfer in granitic rocks

    NASA Astrophysics Data System (ADS)

    Dolejš, David; Wagner, Thomas

    2008-01-01

    We present the results of thermodynamic modeling of fluid-rock interaction in the system Si-Al-Fe-Mg-Ca-Na-H-O-Cl using the GEM-Selektor Gibbs free energy minimization code. Combination of non-ideal mixing properties in solids with multicomponent aqueous fluids represents a substantial improvement and it provides increased accuracy over existing modeling strategies. Application to the 10-component system allows us to link fluid composition and speciation with whole-rock mineralogy, mass and volume changes. We have simulated granite-fluid interaction over a wide range of conditions (200-600 °C, 100 MPa, 0-5 m Cl and fluid/rock ratios of 10-2-104) in order to explore composition of magmatic fluids of variable salinity, temperature effects on fluid composition and speciation and to simulate several paths of alteration zoning. At low fluid/rock ratios (f/r) the fluid composition is buffered by the silicate-oxide assemblage and remains close to invariant. This behavior extends to a f/r of 0.1 which exceeds the amount of exsolved magmatic fluids controlled by water solubility in silicate melts. With increasing peraluminosity of the parental granite, the Na-, K- and Fe-bearing fluids become more acidic and the oxidation state increases as a consequence of hydrogen and ferrous iron transfer to the fluid. With decreasing temperature, saline fluids become more Ca- and Na-rich, change from weakly acidic to alkaline, and become significantly more oxidizing. Large variations in Ca/Fe and Ca/Mg ratios in the fluid are a potential geothermometer. The mineral assemblage changes from cordierite-biotite granites through two-mica granites to chlorite-, epidote- and zeolite-bearing rocks. We have carried out three rock-titration simulations: (1) reaction with the 2 m NaCl fluid leads to albitization, chloritization and desilication, reproducing essential features observed in episyenites, (2) infiltration of a high-temperature fluid into the granite at 400 °C leads to hydrolytic

  14. Evolution of Seawater 44Ca/40Ca Through the Late Cretaceous and Cenozoic

    NASA Astrophysics Data System (ADS)

    Castillo, P. R.; Gopalan, K.; Norris, R. D.; MacIsaac, C.; Liu, X.; MacDougall, J. D.

    2009-12-01

    We analyzed the Ca concentrations and 44Ca/40Ca ratios of surface ocean planktonic (Morozovella, Acarinina, Dentoglobigerina) and benthic (Gavelinella) foraminifera of Late Cretaceous to Late Oligocene ages from DSDP and ODP sites in the Pacific, Atlantic and Indian oceans in order to fill a major gap in the Phanerozoic seawater 44Ca/40Ca curve (Farkass et al., Geochim. Cosmochim. Acta 71, 2007). Our new 44Ca/40Ca data indicate a general increase in foraminiferan-based seawater 44Ca/40Ca from ~-1.3 ‰ δ44Ca/40CaSW in Late Cretaceous to ~0.0 ‰ δ44Ca/40CaSW in Early Miocene (Heuser et al., Paleocean. 20, 2005; Sime et al., Geochim. Cosmochim. Acta 71, 2007). In detail, the 44Ca/40Ca ratio stepped abruptly from ~-1.3 ‰ δ44Ca/40CaSW to a slightly higher value of ~-1.1 ‰ δ44Ca/40CaSW across the Cretaceous-Tertiary (K/T) boundary. A slight positive excursion of ~0.2 ‰ above the background value occurred after the Paleocene Thermal Maximum (55 Ma) but otherwise, the Paleocene to Middle Eocene ratio is relatively stable at ~-1.0 ‰ δ44Ca/40CaSW. The most prominent increase in foraminiferan-based seawater 44Ca/40Ca occurred from Late Eocene to Late Oligocene, roughly coincident with the initial phase of the rapid and steady rise of marine carbonate 87Sr/86Sr ratio in the Tertiary (e.g., DePaolo and Ingram, Science 227, 1985).

  15. Vladimirivanovite, Na6Ca2[Al6Si6O24](SO4,S3,S2,Cl)2 · H2O, a new mineral of sodalite group

    NASA Astrophysics Data System (ADS)

    Sapozhnikov, A. N.; Kaneva, E. V.; Cherepanov, D. I.; Suvorova, L. F.; Levitsky, V. I.; Ivanova, L. A.; Reznitsky, L. Z.

    2012-12-01

    The results of an examination of vladimirivanovite, a new mineral of the sodalite group, found at the Tultui deposit in the Baikal region are discussed. The mineral occurs in the form of outer rims (0.01-3 mm thick) of lazurite, elongated segregations without faced crystals (0.2 to 3-4 mm in size; less frequently, 4 × 12-15 × 20 mm), and rare veinlets (up to 5 mm) hosted in calciphyre and marble. Vladimirivanovite is irregular and patchy dark blue. The mineral is brittle; on average, the microhardness VHN is 522-604, 575 kg/mm2; and the Mohs hardness is 5.0-5.5. The measured and calculated densities are 2.48(3) and 2.436 g/cm3, respectively. Vladimirivanovite is optically biaxial; 2 V meas = 63(±1)°, 2 V calc = 66.2°; the refractive indices are α = 1.502-1.507 (±0.002), N m = 1.509-1.514 (±0.002), and N g = 1.512-1.517 (±0.002). The chemical composition is as follows, wt %: 32.59 SiO2, 27.39 Al2O3, 7.66 CaO, 17.74 Na2O, 11.37 SO3, 1.94 S, 0.12 Cl, and 1.0 H2O; total is 99.62. The empirical formula calculated based on (Si + Al) = 12 with sulfide sulfur determined from the charge balance is Na6.36Ca1.52(Si6.03Al5.97)Σ12O23.99(SO4)1.58(S3)0.17(S2)0.08 · Cl0.04 · 0.62H2O; the idealized formula is Na6Ca2[Al6Si6O24](SO4,S3,S2,Cl)2 · H2O. The new mineral is orthorhombic, space group Pnaa; the unit-cell dimensions are a = 9.066, b = 12.851, c = 38.558 Å, V = 4492 Å3, and Z = 6. The strongest reflections in the X-ray powder diffraction pattern ( dÅ— I[ hkl]) are: 6.61-5[015], 6.43-11[020, 006], 3.71-100[119, 133], 2.623-30[20.12, 240], 2.273-6[04.12], 2.141-14[159, 13.15], 1.783-9[06.12, 04.18], and 1.606-6[080, 00.24]. The crystal structure has been solved with a single crystal. The mineral was named in memoriam of Vladimir Georgievich Ivanov (1947-2002), Russian mineralogist and geochemist. The type material of the mineral is deposited at the Mineralogical Museum of St. Petersburg State University, St. Petersburg, Russia.

  16. Crystal structure of the mineral (Na,Ca,K){sub 2}(Ca,Na){sub 4}(Mg,Fe){sub 5}(Mg,Fe,Ti){sub 5}[Si{sub 12}Al{sub 4}O{sub 44}](F,O){sub 4}: a triclinic representative of the amphibole family

    SciTech Connect

    Rastsvetaeva, R. K. Aksenov, S. M.

    2012-05-15

    A mineral belonging to the amphibole family found at the Rothenberg paleovolcano (Eifel, Germany) was studied by single-crystal X-ray diffraction. The triclinic pseudomonoclinic unit-cell parameters are a = 5.3113(1) Angstrom-Sign , b = 18.0457(3) Angstrom-Sign ; c = 9.8684(2) Angstrom-Sign , {alpha} = 90.016(2) Degree-Sign , {beta} = 105.543(4) Degree-Sign , {gamma} = 89.985(2) Degree-Sign . The structure was solved by direct methods in sp. gr. P1 and refined to the R factor of 2.7% based on 6432 reflections with |F| > 3{sigma}(F) taking into account twinning. The mineral with the idealized formula (Na,Ca,K){sub 2}(Ca,Na){sub 4}(Mg,Fe){sub 5}(Mg,Fe,Ti){sub 5}[Si{sub 12}Al{sub 4}O{sub 44}](F,O){sub 4} has some symmetry and structural features that distinguish it from other minerals of this family.

  17. CD Recorders.

    ERIC Educational Resources Information Center

    Falk, Howard

    1998-01-01

    Discussion of CD (compact disc) recorders describes recording applications, including storing large graphic files, creating audio CDs, and storing material downloaded from the Internet; backing up files; lifespan; CD recording formats; continuous recording; recording software; recorder media; vulnerability of CDs; basic computer requirements; and…

  18. CD Rainbows

    ERIC Educational Resources Information Center

    Ouseph, P. J.

    2007-01-01

    Several papers have been published on the use of a CD as a grating for undergraduate laboratories and/or for high school and college class demonstrations. Four years ago "The Physics Teacher" had a spectacular cover picture showing emission spectrum as viewed through a CD with no coating. That picture gave the impetus to develop a system that can…

  19. Refinement of the canine CD1 locus topology and investigation of antibody binding to recombinant canine CD1 isoforms.

    PubMed

    Schjaerff, Mette; Keller, Stefan M; Fass, Joseph; Froenicke, Lutz; Grahn, Robert A; Lyons, Leslie; Affolter, Verena K; Kristensen, Annemarie T; Moore, Peter F

    2016-03-01

    CD1 molecules are antigen-presenting glycoproteins primarily found on dendritic cells (DCs) responsible for lipid antigen presentation to CD1-restricted T cells. Despite their pivotal role in immunity, little is known about CD1 protein expression in dogs, notably due to lack of isoform-specific antibodies. The canine (Canis familiaris) CD1 locus was previously found to contain three functional CD1A genes: canCD1A2, canCD1A6, and canCD1A8, where two variants of canCD1A8, canCD1A8.1 and canCD1A8.2, were assumed to be allelic variants. However, we hypothesized that these rather represented two separate genes. Sequencing of three overlapping bacterial artificial chromosomes (BACs) spanning the entire canine CD1 locus revealed canCD1A8.2 and canCD1A8.1 to be located in tandem between canCD1A7 and canCD1C, and canCD1A8.1 was consequently renamed canCD1A9. Green fluorescent protein (GFP)-fused canine CD1 transcripts were recombinantly expressed in 293T cells. All proteins showed a highly positive GFP expression except for canine CD1d and a splice variant of canine CD1a8 lacking exon 3. Probing with a panel of anti-CD1 monoclonal antibodies (mAbs) showed that Ca13.9H11 and Ca9.AG5 only recognized canine CD1a8 and CD1a9 isoforms, and Fe1.5F4 mAb solely recognized canine CD1a6. Anti-CD1b mAbs recognized the canine CD1b protein, but also bound CD1a2, CD1a8, and CD1a9. Interestingly, Ca9.AG5 showed allele specificity based on a single nucleotide polymorphism (SNP) located at position 321. Our findings have refined the structure of the canine CD1 locus and available antibody specificity against canine CD1 proteins. These are important fundamentals for future investigation of the role of canine CD1 in lipid immunity. PMID:26687789

  20. AN IMPROVED UNDERSTANDING OF SOIL CD RISK TO HUMANS AND LOW COST METHODS TO PHYTOEXTRACT CD FROM CONTAMINATED SOILS TO PREVENT SOIL CD RISKS

    EPA Science Inventory

    We have described a new paradigm for human risk from soil Cd that reflects many years of agronomic, nutritional and toxicological research. This new model for soil Cd risk reflects the ability of rice to accumulate soil Cd in grain while excluding Fe, Zn and Ca even though the s...

  1. A vibrational spectroscopic study of the phosphate mineral zanazziite - Ca2(MgFe2+)(MgFe2+Al)4Be4(PO4)6ṡ6(H2O)

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Xi, Yunfei; Scholz, Ricardo; Belotti, Fernanda M.; Dias Menezes Filho, Luiz Alberto

    2013-03-01

    Zanazziite is the magnesium member of a complex beryllium calcium phosphate mineral group named roscherite. The studied samples were collected from the Ponte do Piauí mine, located in Itinga, Minas Gerais. The mineral was studied by electron microprobe, Raman and infrared spectroscopy. The chemical formula can be expressed as Ca2.00(Mg3.15,Fe0.78,Mn0.16,Zn0.01,Al0.26,Ca0.14)Be4.00(PO4)6.09(OH)4.00ṡ5.69(H2O) and shows an intermediate member of the zanazziite-greinfeinstenite series, with predominance of zanazziite member. The molecular structure of the mineral zanazziite has been determined using a combination of Raman and infrared spectroscopy. A very intense Raman band at 970 cm-1 is assigned to the phosphate symmetric stretching mode whilst the Raman bands at 1007, 1047, 1064 and 1096 cm-1 are attributed to the phosphate antisymmetric stretching mode. The infrared spectrum is broad and the antisymmetric stretching bands are prominent. Raman bands at 559, 568, 589 cm-1 are assigned to the ν4 out of plane bending modes of the PO4 and HPO4 units. The observation of multiple bands supports the concept that the symmetry of the phosphate unit in the zanazziite structure is reduced in symmetry. Raman bands at 3437 and 3447 cm-1 are attributed to the OH stretching vibrations; Raman bands at 3098 and 3256 are attributed to water stretching vibrations. The width and complexity of the infrared spectral profile in contrast to the well resolved Raman spectra, proves that the pegmatitic phosphates are better studied with Raman spectroscopy.

  2. Synthesis and structural characterization of the ternary Zintl phases AE{sub 3}Al{sub 2}Pn{sub 4} and AE{sub 3}Ga{sub 2}Pn{sub 4} (AE=Ca, Sr, Ba, Eu; Pn=P, As)

    SciTech Connect

    He, Hua; Tyson, Chauntae; Saito, Maia; Bobev, Svilen

    2012-04-15

    Ten new ternary phosphides and arsenides with empirical formulae AE{sub 3}Al{sub 2}Pn{sub 4} and AE{sub 3}Ga{sub 2}Pn{sub 4} (AE=Ca, Sr, Ba, Eu; Pn=P, As) have been synthesized using molten Ga, Al, and Pb fluxes. They have been structurally characterized by single-crystal and powder X-ray diffraction to form with two different structures-Ca{sub 3}Al{sub 2}P{sub 4}, Sr{sub 3}Al{sub 2}As{sub 4}, Eu{sub 3}Al{sub 2}P{sub 4}, Eu{sub 3}Al{sub 2}As{sub 4}, Ca{sub 3}Ga{sub 2}P{sub 4}, Sr{sub 3}Ga{sub 2}P{sub 4}, Sr{sub 3}Ga{sub 2}As{sub 4}, and Eu{sub 3}Ga{sub 2}As{sub 4} crystallize with the Ca{sub 3}Al{sub 2}As{sub 4} structure type (space group C2/c, Z=4); Ba{sub 3}Al{sub 2}P{sub 4} and Ba{sub 3}Al{sub 2}As{sub 4} adopt the Na{sub 3}Fe{sub 2}S{sub 4} structure type (space group Pnma, Z=4). The polyanions in both structures are made up of TrPn{sub 4} tetrahedra, which share common corners and edges to form {sup 2}{sub {infinity}}[TrPn{sub 2}]{sub 3-} layers in the phases with the Ca{sub 3}Al{sub 2}As{sub 4} structure, and {sup 1}{sub {infinity}}[TrPn{sub 2}]{sub 3-} chains in Ba{sub 3}Al{sub 2}P{sub 4} and Ba{sub 3}Al{sub 2}As{sub 4} with the Na{sub 3}Fe{sub 2}S{sub 4} structure type. The valence electron count for all of these compounds follows the Zintl-Klemm rules. Electronic band structure calculations confirm them to be semiconductors. - Graphical abstract: AE{sub 3}Al{sub 2}Pn{sub 4} and AE{sub 3}Ga{sub 2}Pn{sub 4} (AE=Ca, Sr, Ba, Eu; Pn=P, As) crystallize in two different structures-Ca{sub 3}Al{sub 2}P{sub 4}, Sr{sub 3}Al{sub 2}As{sub 4}, Eu{sub 3}Al{sub 2}P{sub 4}, Eu{sub 3}Al{sub 2}As{sub 4}, Ca{sub 3}Ga{sub 2}P{sub 4}, Sr{sub 3}Ga{sub 2}P{sub 4}, Sr{sub 3}Ga{sub 2}As{sub 4}, and Eu{sub 3}Ga{sub 2}As{sub 4}, are isotypic with the previously reported Ca{sub 3}Al{sub 2}As{sub 4} (space group C2/c (No. 15)), while Ba{sub 3}Al{sub 2}P{sub 4} and Ba{sub 3}Al{sub 2}As{sub 4} adopt a different structure known for Na{sub 3}Fe{sub 2}S{sub 4} (space group Pnma (No. 62

  3. The Precise Determination of Cd Isotope Ratio in Geological Samples by MC-ICP-MS with Ion Exchange Separation

    NASA Astrophysics Data System (ADS)

    Du, C.; Hu, S.; Wang, D.; Jin, L.; Guo, W.

    2014-12-01

    Cadmium (Cd) is a trace element which occurs at μg g-1 level abundances in the crust. Cd isotopes have great prospects in the study of the cosmogony, the trace of anthropogenic sources, the micronutrient cycling and the ocean productivity. This study develops an optimized technique for the precise and accurate determination of Cd isotopic compositions. Cd was separated from the matrix by elution with AG-MP-1 anionic exchange chromatographic resin. The matrix elements (K, Na, Ca, Al, Fe, and Mg etc.), polyatomic interfered elements (Ge, Ga, Zr, Nb, Ru, and Mo), and isobaric interfered elements (In, Pd and most of Sn) were eluted using HCl with gradient descent concentrations (2, 0.3, 0.06, 0.012 and 0.0012 mol L-1). The same elution procedure was repeated to eliminate the residuel Sn (Sn/Cd < 0.018). The collected Cd was analyzed using MC-ICP-MS, in which the instrumental mass fractionation was controlled by a "sample-standard bracketing" technique. The recovery of Cd larger than 96.85%, and the δ114/110Cd are in the range of -1.43~+0.20‰ for ten geological reference materials (GSD-3a, GSD-5a, GSD-7a, GSD-6, GSD-9, GSD-10, GSD-11, GSD-12, GSD-23, and GSS-1). The δ114/110Cd obtained for GSS-1 soil sample relative to the NIST SRM 3108 Cd solution was 0.20, which was coherent with the literature values (0.08±0.23). This method had a precision of 0.001~0.002% (RSD), an error range of 0.06~0.14 (δ114/110Cd, 2σ), and a long-term reproducibility of 0.12 (δ114/110Cd, 2σ).

  4. How Does Stochastic Ryanodine Receptor-Mediated Ca Leak Fail to Initiate a Ca Spark?

    PubMed Central

    Sato, Daisuke; Bers, Donald M.

    2011-01-01

    Spontaneous calcium (Ca) sparks are initiated by single ryanodine receptor (RyR) opening. Once one RyR channel opens, it elevates local [Ca] in the cleft space ([Ca]Cleft), which opens other RyR channels in the same Ca release unit (CaRU) via Ca-induced Ca-release. Experiments by Zima et al. (J. Physiol. 588:4743–4757, 2010) demonstrate that spontaneous Ca sparks occur only when intrasarcoplasmic-reticulum (SR) [Ca] ([Ca]SR) is above a threshold level, but that RyR-mediated SR Ca leak exists without Ca sparks well below this threshold [Ca]SR. We examine here how single RyR opening at lower [Ca]SR can fail to recruit Ca sparks at a CaRU, while still contributing to SR Ca leak. We assess this using a physiologically detailed mathematical model of junctional SR Ca release in which RyR gating is regulated by [Ca]SR and [Ca]Cleft. We find that several factors contribute to the failure of Ca sparks as [Ca]SR declines: 1), lower [Ca]SR reduces driving force and thus limits local [Ca]Cleft achieved and the rate of rise during RyR opening; 2), low [Ca]SR limits RyR open time (τO), which further reduces local [Ca]Cleft attained; 3), low τO and fast [Ca]Cleft dissipation after RyR closure shorten the opportunity for neighboring RyR activation; 4), at low [Ca]SR, the RyR exhibits reduced [Ca]Cleft sensitivity. We conclude that all of these factors conspire to reduce the probability of Ca sparks as [Ca]SR declines, despite continued RyR-mediated Ca leak. In addition, these same factors explain the much lower efficacy of L-type Ca channel opening to trigger local SR Ca release at low [Ca]SR during excitation-contraction coupling. Conversely, all of these factors are fundamentally important for increasing the propensity for pro-arrhythmic Ca sparks and waves in cardiac myocytes at high [Ca]SR. PMID:22098735

  5. CD Rom.

    PubMed

    1996-02-01

    A new CD-Rom has been launched by Guy's and St Thomas' Trust's poisonous unit to help health professionals discover which species have been involved in cases of plant poisoning. The unit says thousands of people are poisoned every year by eating or touching plants - the majority of those people affected being under the age of seven. The CD-Rom covers several thousand species of plant, and has been jointly researched with Kew Gardens.

  6. Surface step terrace tuned microstructures and dielectric properties of highly epitaxial CaCu3Ti4O12 thin films on vicinal LaAlO3 substrates

    NASA Astrophysics Data System (ADS)

    Yao, Guang; Gao, Min; Ji, Yanda; Liang, Weizheng; Gao, Lei; Zheng, Shengliang; Wang, You; Pang, Bin; Chen, Y. B.; Zeng, Huizhong; Li, Handong; Wang, Zhiming; Liu, Jingsong; Chen, Chonglin; Lin, Yuan

    2016-10-01

    Controllable interfacial strain can manipulate the physical properties of epitaxial films and help understand the physical nature of the correlation between the properties and the atomic microstructures. By using a proper design of vicinal single-crystal substrate, the interface strain in epitaxial thin films can be well controlled by adjusting the miscut angle via a surface-step-terrace matching growth mode. Here, we demonstrate that LaAlO3 (LAO) substrates with various miscut angles of 1.0°, 2.75°, and 5.0° were used to tune the dielectric properties of epitaxial CaCu3Ti4O12 (CCTO) thin films. A model of coexistent compressive and tensile strained domains is proposed to understand the epitaxial nature. Our findings on the self-tuning of the compressive and tensile strained domain ratio along the interface depending on the miscut angle and the stress relaxation mechanism under this growth mode will open a new avenue to achieve CCTO films with high dielectric constant and low dielectric loss, which is critical for the design and integration of advanced heterostructures for high performance capacitance device applications.

  7. Surface step terrace tuned microstructures and dielectric properties of highly epitaxial CaCu3Ti4O12 thin films on vicinal LaAlO3 substrates

    PubMed Central

    Yao, Guang; Gao, Min; Ji, Yanda; Liang, Weizheng; Gao, Lei; Zheng, Shengliang; Wang, You; Pang, Bin; Chen, Y. B.; Zeng, Huizhong; Li, Handong; Wang, Zhiming; Liu, Jingsong; Chen, Chonglin; Lin, Yuan

    2016-01-01

    Controllable interfacial strain can manipulate the physical properties of epitaxial films and help understand the physical nature of the correlation between the properties and the atomic microstructures. By using a proper design of vicinal single-crystal substrate, the interface strain in epitaxial thin films can be well controlled by adjusting the miscut angle via a surface-step-terrace matching growth mode. Here, we demonstrate that LaAlO3 (LAO) substrates with various miscut angles of 1.0°, 2.75°, and 5.0° were used to tune the dielectric properties of epitaxial CaCu3Ti4O12 (CCTO) thin films. A model of coexistent compressive and tensile strained domains is proposed to understand the epitaxial nature. Our findings on the self-tuning of the compressive and tensile strained domain ratio along the interface depending on the miscut angle and the stress relaxation mechanism under this growth mode will open a new avenue to achieve CCTO films with high dielectric constant and low dielectric loss, which is critical for the design and integration of advanced heterostructures for high performance capacitance device applications. PMID:27703253

  8. Controlling the preferential orientation in sol-gel prepared CaCu3Ti4O12 thin films by LaAlO3 and NdGaO3 substrates

    NASA Astrophysics Data System (ADS)

    Pongpaiboonkul, Suriyong; Kasa, Yumairah; Phokharatkul, Ditsayut; Putasaeng, Bundit; Hodak, Jose H.; Wisitsoraat, Anurat; Hodak, Satreerat K.

    2016-11-01

    Researchers have paid considerable attention to CaCu3Ti4O12 (CCTO) due to the colossal dielectric constant over a wide range of frequency and temperature. Despite of the growing number of works dealing with CCTO, there have been few studies of the role played by the substrate in inducing structural and dielectric effects of this material. In this work, highly-oriented CCTO thin films have been deposited on LaAlO3(100), NdGaO3(100) and NdGaO3(110) substrates using a sol-gel method. These single crystal substrates were chosen in terms of small lattice mismatch between CCTO and the substrate. The X-ray diffraction patterns showed that the CCTO film layers grow with different orientations depending upon the substrate used. We show that the preferred orientation of CCTO thin films can be manipulated to a high degree by growing it on specific crystal planes of the substrates without the use of buffer layers. Colossal dielectric constants are observed in our films which appear to correlate with the film crystallinity and preferred orientation.

  9. Phase Equilibria of ``Cu2O''-``FeO''-CaO-MgO-Al2O3 Slags at PO2 of 10-8.5 atm in Equilibrium with Metallic Copper for a Copper Slag Cleaning Production

    NASA Astrophysics Data System (ADS)

    Henao, Hector M.; Pizarro, Claudio; Font, Jonkion; Moyano, Alex; Hayes, Peter C.; Jak, Evgueni

    2010-12-01

    Limited data are available on phase equilibria of the multicomponent slag system at the oxygen partial pressures used in the copper smelting, converting, and slag-cleaning processes. Recently, experimental procedures have been developed and have been applied successfully to characterize several complex industrial slags. The experimental procedures involve high-temperature equilibration on a substrate and quenching followed by electron probe X-ray microanalysis. This technique has been used to construct the liquidus for the “Cu2O”-“FeO”-SiO2-based slags with 2 wt pct of CaO, 0.5 wt pct of MgO, and 4.0 wt pct of Al2O3 at controlled oxygen partial pressures in equilibrium with metallic copper. The selected ranges of compositions and temperatures are directly relevant to the copper slag-cleaning processes. The new experimental equilibrium results are presented in the form of ternary sections and as a liquidus temperature vs Fe/SiO2 weight ratio diagram. The experimental results are compared with the FactSage thermodynamic model calculations.

  10. Crystal growth of [Ca3Al(OH)6·12H2O]2·(SO4)3·2H2O (ettringite) under microgravity: On the impact of anionicity of polycarboxylate comb polymers

    NASA Astrophysics Data System (ADS)

    Meier, Markus R.; Plank, Johann

    2016-07-01

    The crystallization of ettringite at very early stage (∼10 s crystallization time) prepared by combining Ca(OH)2 and Al2(SO4)3 solutions holding different polycarboxylate (PCE) comb polymers was investigated under microgravity (μg) condition occurring on parabolic flights. The aim was to achieve a more controlled environment for the crystallization than under terrestric conditions. For all experiments, the crystal size, aspect ratio, morphology and amount of ettringite crystals formed under μg were determined. It was observed that due to the absence of convection at μg, crystal growth was generally decelerated as evidenced by the smaller size of the ettringite crystals. Highly anionic and thus strongly adsorbing PCE polymers show a strong impact on the crystal size of ettringite under both 1g and μg conditions. Whereas less anionic, weakly adsorbing PCE polymers exhibit a pronounced effect on ettringite growth only under μg conditions. For them, the diffusion-limited ion transport presents the parameter which determines the crystal size. Another remarkable observation is that under microgravity, some of the polymers change their affinity to specific crystal faces which leads to different aspect ratios compared to terrestric gravity.

  11. Günterblassite, (K,Ca)3 - x Fe[(Si,Al)13O25(OH,O)4] · 7H2O, a new mineral: the first phyllosilicate with triple tetrahedral layer

    NASA Astrophysics Data System (ADS)

    Chukanov, N. V.; Rastsvetaeva, R. K.; Aksenov, S. M.; Pekov, I. V.; Zubkova, N. V.; Britvin, S. N.; Belakovskiy, D. I.; Schüller, W.; Ternes, B.

    2012-12-01

    A new mineral, günterblassite, has been found in the basaltic quarry at Mount Rother Kopf near Gerolstein, Rheinland-Pfalz, Germany as a constituent of the late assemblage of nepheline, leucite, augite, phlogopite, åkermanite, magnetite, perovskite, a lamprophyllite-group mineral, götzenite, chabazite-K, chabazite-Ca, phillipsite-K, and calcite. Günterblassite occurs as colorless lamellar crystals up to 0.2 × 1 × 1.5 mm in size and their clusters. The mineral is brittle, with perfect cleavage parallel to (001) and less perfect cleavage parallel to (100) and (010). The Mohs hardness is 4. The calculated and measured density is 2.17 and 2.18(1) g/cm3, respectively. The IR spectrum is given. The new mineral is optically biaxial and positive as follows: α = 1.488(2), β = 1.490(2), γ = 1.493(2), 2 V meas = 80(5)°. The chemical composition (electron microprobe, average of seven point analyses, H2O is determined by gas chromatography, wt %) is as follows: 0.40 Na2O, 5.18 K2O, 0.58 MgO, 3.58 CaO, 4.08 BaO, 3.06 FeO, 13.98 Al2O3, 52.94 SiO2, 15.2 H2O, and the total is 98.99. The empirical formula is Na0.15K1.24Ba0.30Ca0.72Mg0.16F{0.48/2+}[Si9.91Al3.09O25.25(OH)3.75] · 7.29H2O. The crystal structure has been determined from a single crystal, R = 0.049. Günterblassite is orthorhombic, space group Pnm21; the unit-cell dimensions are a = 6.528(1), b = 6.970(1), c = 37.216(5) Å, V = 1693.3(4) Å3, Z = 2. Günterblassite is a member of a new structural type; its structure is based on three-layer block [Si13O25(OH,O)4]. The strong reflections in the X-ray powder diffraction pattern [ d Å ( I, %) are as follows: 6.532 (100), 6.263 (67), 3.244 (49), 3.062 (91), 2.996 (66), 2.955 (63), and 2.763 (60). The mineral was named in honor of Günter Blass (born in 1943), a well-known amateur mineralogist and specialist in electron microprobe and X-ray diffraction. The type specimen of günterblassite is deposited in the collections of the Fersman Mineralogical Museum of the

  12. Menzerite-(Y) a New Species {(Y REE)(Ca Fe2plus)2}[(Mg Fe2plus)(Fe3plus Al)](Si3)O12 from a Felsic Granulite Parry Sound Ontario and a New Garnet End-member (Y2Ca)Mg2(SiO4)3

    SciTech Connect

    E Grew; J Marsh; M Yates; B Lazic; T Armbruster; A Locock; S Bell; M Dyar; H Bernhardt; O Medenbach

    2011-12-31

    Menzerite-(Y), a new mineral species, forms reddish brown cores, n = 1.844 (20), up to 70 {micro}m across, rimmed successively by euhedral almandine containing up to 2.7 wt% Y{sub 2}O{sub 3} and by K-feldspar in a felsic granulite on Bonnet Island in the interior Parry Sound domain, Grenville Orogenic Province, Canada. It is named after Georg Menzer (1897-1989), the German crystallographer who solved the crystal structure of garnet. Single-crystal X-ray-diffraction results yielded space group Ia3d, a = 11.9947(6) {angstrom}. An electron-microprobe analysis of the grain richest in Y (16.93 wt% Y{sub 2}O{sub 3}) gave the following formula, normalized to eight cations and 12 oxygen atoms: {l_brace}Y{sub 0.83}Gd{sub 0.01}Dy{sub 0.05}Ho{sub 0.02}Er{sub 0.07}Tm{sub 0.01}Yb{sub 0.06}Lu{sub 0.02}Ca{sub 1.37}Fe{sub 0.49}{sup 2+}Mn{sub 0.07}{r_brace} [Mg{sub 0.55}Fe{sub 0.42}{sup 2+}Fe{sub 0.58}{sup 3+}Al{sub 0.35} V{sub 0.01}Sc{sub 0.01}Ti{sub 0.08}](Si{sub 2.82}Al{sub 0.18})O{sub 12}, or {l_brace}(Y,REE)(Ca,Fe{sup 2+}){sub 2}{r_brace}[(Mg,Fe{sup 2+})(Fe{sup 3+},Al)](Si{sub 3})O{sub 12}. Synchrotron micro-XANES data gave Fe{sup 3+}/{Sigma}Fe = 0.56(10) versus 0.39(2) calculated from stoichiometry. The scattering power refined at the octahedral Y site, 17.68 epfu, indicates that a relatively light element contributes to its occupancy. Magnesium, as determined by electron-microprobe analyses, would be a proper candidate. In addition, considering the complex occupancy of this site, the average Y-O bond length of 2.0244(16) {angstrom} is in accord with a partial occupancy by Mg. The dominance of divalent cations with Mg > Fe{sup 2+} and the absence of Si at the octahedral Y site (in square brackets) are the primary criteria for distinguishing menzerite-(Y) from other silicate garnet species; the menzerite-(Y) end-member is {l_brace}Y{sub 2}Ca{r_brace}[Mg{sub 2}](Si{sub 3})O{sub 12}. The contacts of menzerite-(Y) with almandine are generally sharp and, in places, cuspate. It is

  13. Chitosan film loaded with silver nanoparticles-sorbent for solid phase extraction of Al(III), Cd(II), Cu(II), Co(II), Fe(III), Ni(II), Pb(II) and Zn(II).

    PubMed

    Djerahov, Lubomir; Vasileva, Penka; Karadjova, Irina; Kurakalva, Rama Mohan; Aradhi, Keshav Krishna

    2016-08-20

    The present study describes the ecofriendly method for the preparation of chitosan film loaded with silver nanoparticles (CS-AgNPs) and application of this film as efficient sorbent for separation and enrichment of Al(III), Cd(II), Cu(II), Co(II), Fe(III), Ni(II), Pb(II) and Zn(II). The stable CS-AgNPs colloid was prepared by dispersing the AgNPs sol in chitosan solution at appropriate ratio and further used to obtain a cast film with very good stability under storage and good mechanical strength for easy handling in aqueous medium. The incorporation of AgNPs in the structure of CS film and interaction between the polymer matrix and nanoparticles were confirmed by UV-vis and FTIR spectroscopy. The homogeneously embedded AgNPs (average diameter 29nm, TEM analysis) were clearly observed throughout the film by SEM. The CS-AgNPs nanocomposite film shows high sorption activity toward trace metals under optimized chemical conditions. The results suggest that the CS-AgNPs nanocomposite film can be feasibly used as a novel sorbent material for solid-phase extraction of metal pollutants from surface waters.

  14. Lck Mediates Signal Transmission from CD59 to the TCR/CD3 Pathway in Jurkat T Cells

    PubMed Central

    Lipp, Anna M.; Juhasz, Kata; Paar, Christian; Ogris, Christoph; Eckerstorfer, Paul; Thuenauer, Roland; Hesse, Jan; Nimmervoll, Benedikt; Stockinger, Hannes; Schütz, Gerhard J.; Bodenhofer, Ulrich

    2014-01-01

    The glycosylphosphatidylinositol (GPI)-anchored molecule CD59 has been implicated in the modulation of T cell responses, but the underlying molecular mechanism of CD59 influencing T cell signaling remained unclear. Here we analyzed Jurkat T cells stimulated via anti-CD3ε- or anti-CD59-coated surfaces, using time-resolved single-cell Ca2+ imaging as a read-out for stimulation. This analysis revealed a heterogeneous Ca2+ response of the cell population in a stimulus-dependent manner. Further analysis of T cell receptor (TCR)/CD3 deficient or overexpressing cells showed that CD59-mediated signaling is strongly dependent on TCR/CD3 surface expression. In protein co-patterning and fluorescence recovery after photobleaching experiments no direct physical interaction was observed between CD59 and CD3 at the plasma membrane upon anti-CD59 stimulation. However, siRNA-mediated protein knock-downs of downstream signaling molecules revealed that the Src family kinase Lck and the adaptor molecule linker of activated T cells (LAT) are essential for both signaling pathways. Furthermore, flow cytometry measurements showed that knock-down of Lck accelerates CD3 re-expression at the cell surface after anti-CD59 stimulation similar to what has been observed upon direct TCR/CD3 stimulation. Finally, physically linking Lck to CD3ζ completely abolished CD59-triggered Ca2+ signaling, while signaling was still functional upon direct TCR/CD3 stimulation. Altogether, we demonstrate that Lck mediates signal transmission from CD59 to the TCR/CD3 pathway in Jurkat T cells, and propose that CD59 may act via Lck to modulate T cell responses. PMID:24454946

  15. A semi-empirical thermodynamic formalism for high-pressure aqueous silicate solutions in the model system K2O-Na2O-CaO-MgO-Al2O3-SiO2-H2O-CO2, a first approach

    NASA Astrophysics Data System (ADS)

    Schertl, H.; Burchard, M.; Hertwig, A.; Maresch, W. V.

    2012-12-01

    The results of experimental solubility determinations in aqueous solutions at high pressures up to 5 GPa are often difficult to gauge with respect to precision and accuracy, because of the potential uncertainties inherent in the available experimental approaches. Existing models of aqueous silicate solutions at low pressures are either unsuitable for extrapolation beyond 0.5 to 1.0 GPa or involve polynomial fits in which the fit parameters lack direct physical meaning. An approach described by Gerya et al. [1,2], based on statistical thermodynamics, allows aqueous silicate solutions to be described as mixtures of fictive oxide "components" together with water molecules in both clustered and "gas-like", i.e. unassociated, states. Burchard et al. [3] presented a first data set for fluids in the system CaO-SiO2-H2O, using the statistical thermodynamic formulation of Gerya et al [1,2] and extending it to include charged fluid species such as Ca2+, Ca(OH)+, Ca(OH)2, OH- and H+. We have now further developed the data set of Burchard et al. [3] by including carbonic fluid species and extending the model system to include MgO and Al2O3. In addition, initial progress has been made in including potassium and sodium model species. Solid phase data were obtained by mathematical conversion of existing thermodynamic mineral data into the semi-empirical form. With this semi-empirical data set calculations for simple, "wet" silicate rocks are now possible. We present applications to suites of jadeitites and jadeite-lawsonite-quartz rocks from the Rio San Juan serpentinite mélanges of the northern Dominican Republic. These rocks have crystallized from high-pressure aqueous fluids in a long-lived intra-oceanic subduction-zone environment at various times and at different P-T conditions (Schertl et al. [4]). The fluid-rock interactions leading to these spectacular rocks are still poorly understood. [1] Gerya et al. (2004) Phys. Chem. Minerals 31, 429-455; [2] Gerya et al. (2005) Eur

  16. Nitric Oxide is Involved in the Upregulation of IFN-γ and IL-10 mRNA Expression by CD8+ T Cells During the Blood Stages of P. chabaudi AS Infection in CBA/Ca Mice

    PubMed Central

    Legorreta-Herrera, M; Rivas-Contreras, S; Ventura-Gallegos, JL; Zentella-Dehesa, A

    2011-01-01

    Nitric oxide (NO) is involved in the clearance of several types of bacteria, viruses and parasites. Although the roles of NO and CD8+ T cells in the immune response to malaria have been extensively studied, their actual contributions during the blood stages of malaria infection remain unclear. In this work, we corroborate that serum NO levels are not associated with the in vivo elimination of the blood stages of Plasmodium chabaudi AS. In addition, we show that CD8+ T cells exhibit increased apoptosis and up regulate the expression of TNF-α mRNA on day 4 post-infection and IFN-γ and IL-10 mRNA on day 11 post-infection. Interestingly, only the levels of IFN-γ and IL-10 expression are affected when iNOS is inhibited with aminoguanidine (AG), suggesting that NO could be involved in the activation of CD8+ T cells during the blood stages of plasmodium infection. PMID:22110391

  17. Melting in the system CaO-MgO-Al2O3-SiO2-FeO-Cr2O3 spanning the plagioclase-spinel lherzolite transition at 7 to 10 kbar: experiments versus thermodynamics

    NASA Astrophysics Data System (ADS)

    Keshav, S.; Tirone, M.; Gudfinnsson, G.; Presnall, D.

    2008-12-01

    Voluminous basaltic magmas erupt at mid-oceanic ridges (mid-ocean ridge basalts, MORB) as a consequence of mantle upwelling and melting beneath spreading plates. However, because the geochemistry of MORB is distinct from OIB (ocean-island basalts), both have great petrogenetic significance and carry important information about the chemical and physical properties/dynamics of the mantle. In the context of MORB, a critical yet unresolved question is how phase transitions within a polybaric melting zone affect melt productivity and thereby, possibly exert control on major and trace element composition of erupted magmas. Currently, the disagreements on these issues are fundamental, with great consequences that extend beyond petrology to global issues of potential temperatures, mantle melting, mantle heterogeneity, and mantle dynamics. Thermodynamics show that melt productivity depends critically on the transition reaction, and melting can in principle increase, decrease, or even stop at a transition. Phase equilibrium work from both systems CaO-MgO-Al2O3-SiO2-Na2O (CMASN) and CMAS-FeO (CMASF) have been used to argue that melt productivity may increase at the plagioclase-spinel (pl-sp) transition because the univariant solidus transition reaction has a positive dT/dP slope in these systems, moving to higher pressure relative to the CMAS system. However, melting models derived on the basis of MELTS and pMELTS show that the solidus has a negative slope on the pl-sp transition. If correct, this would cause suppression of melting as the mantle decompresses along a pertinent adiabat. Owing to these vast discrepancies between experiments and thermodynamics and to further clarify MORB genesis, in this work we present melting phase relations in the system CMASFCr at the plagioclase-spinel lherzolite transition from 7 to 10 kbar. Cr was chosen since recent work has shown that the addition of Cr to CMAS has an unusually large effect on Ca/Al of melt compositions at 1.1 GPa. With

  18. Development and characterization of glass-ceramic sealants in the (CaO-Al2O3-SiO2-B2O3) system for Solid Oxide Electrolyzer Cells

    NASA Astrophysics Data System (ADS)

    Khedim, Hichem; Nonnet, Hélène; Méar, François O.

    2012-10-01

    The efficiency of glass-ceramic sealants plays a crucial role in Solid Oxide Electrolyzer Cell performance and durability. In order to develop suitable sealants, operating around 800 °C, two parent glass compositions, CAS1B and CAS2B, from the CaO-Al2O3-SiO2-B2O3 system were prepared and explored. The thermal and physicochemical properties of the glass ceramics and their crystallization behavior were investigated by HSM, DTA and XRD analyses. The microstructure and chemical compositions of the crystalline phases were investigated by microprobe analysis. Bonding characteristic as well as chemical interactions of the parent glass with yttria-stabilized zirconia (YSZ) electrolyte and ferritic steel-based interconnect (Crofer®) were also investigated. The preliminary results revealed the superiority of CAS2B glass for sealing application in SOECs. The effect of minor additions of V2O5, K2O and TiO2 on the thermal properties was also studied and again demonstrated the advantages of the CAS2B glass composition. Examining the influence of heat treatment on the seal behavior showed that the choice of the heating rate is a compromise between delaying the crystallization process and delaying the viscosity drop. The thermal Expansion Coefficients (TEC) obtained for the selected glass ceramic are within the desired range after the heat treatment of crystallization. The crystallization kinetic parameters of the selected glass composition were also determined under non-isothermal conditions by means of differential thermal analysis (DTA) and using the formal theory of transformations for heterogeneous nucleation.

  19. Esperanzaite, NaCa(2)Al(2)(As(5+)O(4))[As(5+)O(3)(OH)](OH)(2)F(4)(H(2)O), A New Mineral From Mina La Esperanza, Mexico: Descriptive Mineralogy and Atomic Arrangement

    SciTech Connect

    Cureton, F.; Falster, A.U.; Foord, E.E.; Hlava, P.F.; Hughes, J.M.; Maxwell, C.H.

    1998-11-09

    Esperanzaite, ideally NaCazA12(As5+0.i)[As5+03 (OH)] (OH)2FJH20), Z =2, is a new mineral from the Mina h Esperarq Durango State, Mexico. The mineral occurs as blue-green botryoidal crystalline masses on rhyolite, with separate spheres up to 1.5 mm Y Deceased in diameter. Mobs hardness is 4.5, specific gravity 3.240h, and 3.36( 3)C.IC. Optical properties were measured in 589 nm light. Esperanzaite is biaxial (-), .Y= Y = Z= colorless, a 1.580(1), ~ 1.588( 1), and y 1.593(1 ); 2V0hs is 74(1 ~ and 2 }'CUIC is 76.3". Dispersion is medium, r < v, and optic axes are oriented as a A Z = +50.5o, b = Y, c P. X = +35". The five strongest X-ray diffraction maxima in the powder pattern are (~ /, hk~: 2.966,100, 13 i, 31 i, 031 ; 3.527,90, 220; 2.700,90,221,002, 040; 5.364>80, 001, 020; 4.796,80,011. Esperanzaite is monoclinic, u 9.687(5), b 10.7379(6), c 5.5523(7)& ~ 105.32( 1 )", space group P21/nz. The atomic arrangement of esperanzaite was solved by Direct Methods and Fourier analysis (R= 0.03 1). The Fundamental Building Block is formed of stacks of heteropolyhedral tetramers; the tetramers are formed of two arsenate tetrahedral and two Al octahedra, comer-linked in 4-member rings. The Fundamental Building Blocks are linked by irregular lda~j and Ca@ polyhedra.

  20. Three series of quaternary rare-earth transition-metal pnictides with CaAl2Si2-type structures: RECuZnAs2, REAgZnP2, and REAgZnAs2

    NASA Astrophysics Data System (ADS)

    Stoyko, Stanislav S.; Ramachandran, Krishna K.; Blanchard, Peter E. R.; Rosmus, Kimberly A.; Aitken, Jennifer A.; Mar, Arthur

    2014-05-01

    Three series of quaternary rare-earth transition-metal pnictides REMM‧Pn2 (M=Cu, Ag; M‧=Zn; Pn=P, As) have been prepared by reaction of the elements at 800 °C, with crystal growth promoted through the addition of iodine. The extent of RE substitution is broad in these series: RECuZnAs2 (RE=Y, Lasbnd Nd, Sm, Gd-Lu), REAgZnP2 (RE=La-Nd, Sm, Gd-Dy), and REAgZnAs2 (RE=Lasbnd Nd, Sm, Gdsbnd Dy). Powder and single-crystal X-ray diffraction analysis revealed that they adopt the trigonal CaAl2Si2-type structure (space group P3barm1, Z=1), in which Cu or Ag atoms are disordered with Zn atoms over the unique tetrahedrally coordinated transition-metal site. Magnetic measurements indicated Curie-Weiss behavior for several members of the RECuZnAs2 and REAgZnP2 series. Core-line X-ray photoelectron spectra (XPS) collected on some RECuZnAs2 members corroborate the charge assignment deduced by the Zintl concept for these compounds, (RE3+)(M1+)(Zn2+)(Pn3-)2. Optical diffuse reflectance spectra and valence band XPS spectra established that these compounds are small band-gap semiconductors (up to ~0.8 eV in REAgZnP2) or semimetals (RECuZnAs2). Band structure calculations also support this electronic structure and indicate that the band gap can be narrowed through appropriate chemical substitution (RE=smaller atoms, M=Cu, and Pn=As).

  1. Atomic data from the iron project. 3: Rate coefficients for electron impact excitation of boron-like ions: Ne VI, Mg VIII, Al IX, Si X, S XII, Ar XIV, Ca XVI and Fe XXII

    NASA Technical Reports Server (NTRS)

    Zhang, Hong Lin; Graziani, Mark; Pradhan, Anil K.

    1994-01-01

    Collison strengths and maxwellian averaged rate coefficients have been calculated for the 105 transitions among all 15 fine structure levels of the 8 LS terms 2s(sup 2) 2 P(P-2(sup 0 sub 1/, 3/2)), 2s2p(sup 2)(P-4(sub 1/2,3/2,5/2), D-2(sub 3/2, 5/2), S-2(sub 1/2), P-2(sub 1/2, 3/2)), 2p(sup 3)(S-4(sup 0)(sub 3/2), D-2(sup 0 sub 3/2, 5/2), P-2(sup 0 sub 1/2, 3/2)) in highly- charged B-like Ne, Mg, Al, Si, S, Ar, Ca and Fe. Rate coefficients have been tabulated at a wide range of temperatures, depending on the ion charge and abundance in plasma sources. Earlier work for O IV has also been extended to include the high temperature range. A brief discussion of the calculations, sample results, and comparison with earlier works is also given. While much of the new data should be applicable to UV spectral diagnostics, the new rates for the important ground state fine structure transition P-2(sup 0 sub 1/2)-P-2(sup 0 sub 3/2) should result in significant revision of the IR cooling rates in plasmas where B-like ions are prominent constituents, since the new rate coefficients are generally higher by several factors compared with the older data.

  2. Crystal and electronic structures, luminescence properties of Eu{sup 2+}-doped Si{sub 6-z}Al{sub z}O{sub z}N{sub 8-z} and M{sub y}Si{sub 6-z}Al{sub z-y}O{sub z+y}N{sub 8-z-y} (M=2Li, Mg, Ca, Sr, Ba)

    SciTech Connect

    Li, Y.Q. Hirosaki, N.; Xie, R.J.; Takeda, T.; Mitomo, M.

    2008-12-15

    The crystal structure, electronic structure, and photoluminescence properties of Eu{sub x}Si{sub 6-z}Al{sub z-x}O{sub z+x}N{sub 8-z-x} (x=0-0.1, 0Al{sub z-x-y}O{sub z+x+y}N{sub 8-z-x-y} (M=2Li, Mg, Ca, Sr, Ba) have been studied. Single-phase Eu{sub x}Si{sub 6-z}Al{sub z-x}O{sub z+x}N{sub 8-z-x} can be obtained in very narrow ranges of x{<=}0.06 (z=0.15) and z<0.5 (x=0.3), indicating that limited Eu{sup 2+} ions can be incorporated into nitrogen-rich Si{sub 6-z}Al{sub z}O{sub z}N{sub 8-z}. The Eu{sup 2+} ion is found to occupy the 2b site in a hexagonal unit cell (P6{sub 3}/m) and directly connected by six adjacent nitrogen/oxygen atoms ranging 2.4850-2.5089 A. The calculated host band gaps by the relativistic DV-X{alpha} method are about 5.55 and 5.45 eV (without Eu{sup 2+} 4f5d levels) for x=0 and 0.013 in Eu{sub x}Si{sub 6-z}Al{sub z-x}O{sub z+x}N{sub 8-z-x} (z=0.15), in which the top of the 5d orbitals overlap with the Si-3s3p and N-2p orbitals within the bottom of the conduction band of the host. Eu{sub x}Si{sub 6-z}Al{sub z-x}O{sub z+x}N{sub 8-z-x} shows a strong green emission with a broad Eu{sup 2+} band centered at about 530 nm under UV to near-UV excitation range. The excitation and emission spectra are hardly modified by Eu concentration and dual-doping ions of Li and other alkaline-earth ions with Eu. Higher Eu concentrations can significantly quench the luminescence of Eu{sup 2+} and decrease the thermal quenching temperature. In addition, the emission spectrum can only be slightly tuned to the longer wavelengths ({approx}529-545 nm) by increasing z within the solid solution range of z<0.5. Furthermore, the luminescence intensity of Eu{sub x}Si{sub 6-z}Al{sub z-x}O{sub z+x}N{sub 8-z-x} can be improved by increasing z and the dual-doping of Li and Ba. - Graphical abstract: Excitation and emission spectra of Eu{sub x}Si{sub 6-z}Al{sub z-x}O{sub z+x}N{sub 8-z-x} with the project of a 2x2x2 supercell crystal structure

  3. Differential response of human thymus cells to CD2 antibodies: fragmentation of DNA of CD45RO+ and proliferation of CD45RO- subsets.

    PubMed Central

    Li, J; Campbell, D; Hayward, A R

    1992-01-01

    Human thymocytes bearing the CD45RO 'memory' cell phenotype do not proliferate in concanavalin A (Con A)-stimulated cultures and may be destined for intrathymic death. To determine whether this subset would exhibit characteristics of programmed cell death (apoptosis), we examined the integrity of the nuclear DNA by gel electrophoresis. DNA fragmentation was restricted to the CD45RO+ subset of human thymocytes following exposure to stimulating concentrations of anti-CD2 antibodies. Both CD45RO- and CD45RO+ subsets mobilized cytoplasmic Ca2+ following cell-surface CD2 ligation, but entry into the cell cycle and vigorous thymidine uptake were restricted to the CD45RO- subset. Our results provide a mechanism which may account for the failure of thymic CD45RO+ cells to respond to stimuli which elicit proliferation by the reciprocal CD45RA+ subset. Images Figure 1 Figure 2 PMID:1348052

  4. Synthesis and characterization of phosphates in molten systems Cs{sub 2}O-P{sub 2}O{sub 5}-CaO-M{sup III}{sub 2}O{sub 3} (M{sup III}-Al, Fe, Cr)

    SciTech Connect

    Zatovsky, Igor V.; Strutynska, Nataliya Yu.; Baumer, Vyacheslav N.; Slobodyanik, Nikolay S.; Ogorodnyk, Ivan V.; Shishkin, Oleg V.

    2011-03-15

    The crystallization of complex phosphates from the melts of Cs{sub 2}O-P{sub 2}O{sub 5}-CaO-M{sup III}{sub 2}O{sub 3} (M{sup III}-Al, Fe, Cr) systems have been investigated at fixed value Cs/P molar ratios equal to 0.7, 1.0 and 1.3 and Sa/P=0.2 and Ca/M{sup III}=1. The fields of crystallization of CsCaP{sub 3}O{sub 9}, {beta}-Ca{sub 2}P{sub 2}O{sub 7}, Cs{sub 2}CaP{sub 2}O{sub 7}, Cs{sub 3}CaFe(P{sub 2}O{sub 7}){sub 2}, Ca{sub 9}M{sup III}(PO{sub 4}){sub 7} (M{sup III}-Fe, Cr), Cs{sub 0.63}Ca{sub 9.63}Fe{sub 0.37}(PO{sub 4}){sub 7} and CsCa{sub 10}(PO{sub 4}){sub 7} were determined. Obtained phosphates were investigated using powder X-ray diffraction and FTIR spectroscopy. Novel whitlockite-related phases CsCa{sub 10}(PO{sub 4}){sub 7} and Cs{sub 0.63}Ca{sub 9.63}Fe{sub 0.37}(PO{sub 4}){sub 7} have been characterized by single crystal X-ray diffraction: space group R3c, a=10.5536(5) and 10.5221(4) A, c=37.2283(19) and 37.2405(17) A, respectively. -- Graphical Abstract: Structural relationships between {beta}-Ca{sub 3}(PO{sub 4}){sub 2} and synthesized compounds is shown in terms aliovalent substitution of calcium atoms, which residue on three-fold axis, by other metals in {beta}-Ca{sub 3}(PO{sub 4}){sub 2} framework. Display Omitted Research highlights: {yields} Phase formation in the melts of Cs{sub 2}O-P{sub 2}O{sub 5}-CaO-M{sup III}{sub 2}O{sub 3} (M{sup III}-Al, Fe, Cr) systems were determined. {yields} The composition and structure of the compounds depend on the nature of M{sup III} and initial ratio of Cs/P. {yields} Obtained compounds have been characterized by powder X-ray diffraction and FTIR spectroscopy. {yields} Crystal structures of CsCa{sub 10}(PO{sub 4}){sub 7} and Cs{sub 0.63}Ca{sub 9.63}Fe{sub 0.37}(PO{sub 4}){sub 7} were determined by single crystal XRD.

  5. A new method for 44Ca/40Ca determination using cool plasma MC-ICP-MS

    NASA Astrophysics Data System (ADS)

    Fietzke, J.; Eisenhauer, A.; Liebetrau, V.; Bock, B.; Gussone, N.; Nägler, T. F.; Dietzel, M.; Spero, H.; Bijma, J.; Dullo, C.

    2003-04-01

    Here we present a new technique for the direct measurement of 44Ca/40Ca isotope ratios on a MC-ICP-MS (Axiom) using the "cool plasma" technique. By reducing the plasma energy from about 1250 Watts to 400 Watts the isobaric effect resulting from 40Ar^+ can be significantly reduced enabling the simultaneous and precise measurement of 44Ca and 40Ca beam intensities in different Faraday cups. In contrast to the TIMS technique requiring a Ca double spike the isotope measurements on a MC-ICP-MS can be performed by bracketing standards. This reduces the effort for chemical preparations without loss of precision. Isobaric effects of MgO^+ and NaOH^+ interfering with 40Ca and MgOH_2 with 44Ca can be neglected by measuring Ca isotopes near the low mass edge of the peaks. No influences of Sr2+ were found monitoring on 43.5amu. Repeated measurements of two Johnson Matthey CaCO_3 standards (lot No. 4064 and lot No. 9912) revealed values of about -11.29 ppm and 0.57 ppm. These values are in accordance with previous values published by Russel et al. (1978) and Heuser et al. (2002). Repeated measurement of the NIST 915a CaCO_3 standard showed that the variance of a single δ44Ca measurement is about 0.28 ppm (2SD) being comparable with TIMS. MC-ICP-MS based δ44Ca values measured on inorganic precipitates are indistinguishable from earlier measurements of Gussone et al. (in press) based on TIMS δ44Ca measurements confirming that there is a positive δ44Ca-temperature gradient. Our study demonstrates the possibility to measure the whole dispersion of Ca isotopes with a MC-ICP-MS showing that 40Ca can be used for normalization of 44Ca. References Russel W. A. et al. (1978) Ca isotope fractionation on the Earth and other solar system materials. Geochim. Cosmochim. Acta 42, 1075--1090. Heuser A. et al. (2002) Measurement of Calcium Isotopes (δ44Ca) Using a Multicollector TIMS Technique. Int. J. Mass Spec. 220, 387--399. Gussone N. et al. (in press) Model for Kinetic Effects on

  6. Deep sequencing of mRNA in CD24(-) and CD24(+) mammary carcinoma Mvt1 cell line.

    PubMed

    Rostoker, Ran; Jayaprakash, Anitha D; Sachidanandam, Ravi; LeRoith, Derek

    2015-09-01

    CD24 is an anchored cell surface marker that is highly expressed in cancer cells (Lee et al., 2009) and its expression is associated with poorer outcome of cancer patients (Kristiansen et al., 2003). Phenotype comparison between two subpopulations derived from the Mvt1 cell line, CD24(-) cells (with no CD24 cell surface expression) and the CD24(+) cells, identified high tumorigenic capacity for the CD24(+) cells. In order to reveal the transcripts that support the CD24(+) aggressive and invasive phenotype we compared the gene profiles of these two subpopulations. mRNA profiles of CD24(-) and CD24(+) cells were generated by deep sequencing, in triplicate, using an Illumina HiSeq 2500. Here we provide a detailed description of the mRNA-seq analysis from our recent study (Rostoker et al., 2015). The mRNA-seq data have been deposited in the NCBI GEO database (accession number GSE68746).

  7. Cadmium inhibition of Ca sup 2+ uptake in rainbow trout gills

    SciTech Connect

    Verbost, P.M.; Flik, G.; Lock, R.A.C.; Wendelaar Bonga, E.E. )

    1987-08-01

    The effects of cadmium (Cd{sup 2+}) on calcium (Ca{sup 2+}) transport in the gills of rainbow trout (Salmo gairdneri) were studied. The gill epithelium of freshwater fish represents a model for a Ca{sup 2+}-transporting tight epithelium. Unidirectional {sup 45}Ca{sup 2+} fluxes in the gills were estimated in an isolated saline-perfused heat preparation. {sup 45}Ca{sup 2+} influx was not affected when up to 10 {mu}M Cd were added to the ventilatory water at the start of flux determinations (in vitro exposure). However, after 16 h in vivo preexposure of the fish to 0.1 {mu}M Cd in the water, a 79% inhibition of Ca{sup 2+} influx was observed. Ca{sup 2+} efflux was not affected when up to 10 {mu}M Cd were added to the ventilatory water during the flux determination. Ca{sup 2+} efflux in fish preexposed to 0.1 {mu}M Cd for 16 h was also not affected; a preexposure to 1 {mu}M Cd, however, resulted in a 173% increase in Ca{sup 2+} efflux rates. Tracer retention in the gill tissue indicated that both Ca{sup 2+} and Cd{sup 2+} enter the gill epithelium via a lanthanum (La{sup 3+})-inhibitable pathway. It is concluded that Cd{sup 2+} readily enters the branchial epithelial cells, similarly as Ca{sup 2+} does via La{sup 3+}-sensitive apical Ca{sup 2+} channels. The inhibitory action of Cd{sup 2+} on transepithelial Ca{sup 2+} influx seems to result from an inhibition of the basolateral Ca{sup 2+} transport, occurring after a critical intracellular Cd{sup 2+} concentration has been reached.

  8. Glass-ceramic nuclear waste forms obtained by crystallization of SiO 2-Al 2O 3-CaO-ZrO 2-TiO 2 glasses containing lanthanides (Ce, Nd, Eu, Gd, Yb) and actinides (Th): Study of the crystallization from the surface

    NASA Astrophysics Data System (ADS)

    Loiseau, P.; Caurant, D.

    2010-07-01

    Glass-ceramic materials containing zirconolite (nominally CaZrTi 2O 7) crystals in their bulk can be envisaged as potential waste forms for minor actinides (Np, Am, Cm) and Pu immobilization. In this study such matrices are synthesized by crystallization of SiO 2-Al 2O 3-CaO-ZrO 2-TiO 2 glasses containing lanthanides (Ce, Nd, Eu, Gd, Yb) and actinides (Th) as surrogates. A thin partially crystallized layer containing titanite and anorthite (nominally CaTiSiO 5 and CaAl 2Si 2O 8, respectively) growing from glass surface is also observed. The effect of the nature and concentration of surrogates on the structure, the microstructure and the composition of the crystals formed in the surface layer is presented in this paper. Titanite is the only crystalline phase able to significantly incorporate trivalent lanthanides whereas ThO 2 precipitates in the layer. The crystal growth thermal treatment duration (2-300 h) at high temperature (1050-1200 °C) is shown to strongly affect glass-ceramics microstructure. For the system studied in this paper, it appears that zirconolite is not thermodynamically stable in comparison with titanite growing form glass surface. Nevertheless, for kinetic reasons, such transformation (i.e. zirconolite disappearance to the benefit of titanite) is not expected to occur during interim storage and disposal of the glass-ceramic waste forms because their temperature will never exceed a few hundred degrees.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  10. Dependences of the density of M{sub 1-x}R{sub x}F{sub 2+x} and R{sub 1-y}M{sub y}F{sub 3-y} single crystals (M = Ca, Sr, Ba, Cd, Pb; R means rare earth elements) on composition

    SciTech Connect

    Sorokin, N. I. Krivandina, E. A.; Zhmurova, Z. I.

    2013-11-15

    The density of single crystals of nonstoichiometric phases Ba{sub 1-x}La{sub x}F{sub 2+x} (0 {<=} x {<=} 0.5) and Sr{sub 0.8}La{sub 0.2-x}Lu{sub x}F{sub 2.2} (0 {<=} x {<=} 0.2) with the fluorite (CaF{sub 2}) structure type and R{sub 1-y}Sr{sub y}F{sub 3-y} (R = Pr, Nd; 0 {<=} y {<=} 0.15) with the tysonite (LaF{sub 3}) structure type has been measured. Single crystals were grown from a melt by the Bridgman method. The measured concentration dependences of single crystal density are linear. The interstitial and vacancy models of defect formation in the fluorite and tysonite phases, respectively, are confirmed. To implement the composition control of single crystals of superionic conductors M{sub 1-x}R{sub x}F{sub 2+x} and R{sub 1-y}M{sub y}F{sub 3-y} in practice, calibration graphs of X-ray density in the MF{sub 2}-RF{sub 3} systems (M = Ca, Sr, Ba, Cd, Pb; R = La-Lu, Y) are plotted.

  11. Ca-Dependent Folding of Human Calumenin.

    PubMed

    Mazzorana, Marco; Hussain, Rohanah; Sorensen, Thomas

    2016-01-01

    Human calumenin (hCALU) is a six EF-hand protein belonging to the CREC family. As other members of the family, it is localized in the secretory pathway and regulates the activity of SERCA2a and of the ryanodine receptor in the endoplasmic reticulum (ER). We have studied the effects of Ca2+ binding to the protein and found it to attain a more compact structure upon ion binding. Circular Dichroism (CD) measurements suggest a major rearrangement of the protein secondary structure, which reversibly switches from disordered at low Ca2+ concentrations to predominantly alpha-helical when Ca2+ is added. SAXS experiments confirm the transition from an unfolded to a compact structure, which matches the structural prediction of a trilobal fold. Overall our experiments suggest that calumenin is a Ca2+ sensor, which folds into a compact structure, capable of interacting with its molecular partners, when Ca2+ concentration within the ER reaches the millimolar range. PMID:26991433

  12. Ca-Dependent Folding of Human Calumenin

    PubMed Central

    Mazzorana, Marco; Hussain, Rohanah; Sorensen, Thomas

    2016-01-01

    Human calumenin (hCALU) is a six EF-hand protein belonging to the CREC family. As other members of the family, it is localized in the secretory pathway and regulates the activity of SERCA2a and of the ryanodine receptor in the endoplasmic reticulum (ER). We have studied the effects of Ca2+ binding to the protein and found it to attain a more compact structure upon ion binding. Circular Dichroism (CD) measurements suggest a major rearrangement of the protein secondary structure, which reversibly switches from disordered at low Ca2+ concentrations to predominantly alpha-helical when Ca2+ is added. SAXS experiments confirm the transition from an unfolded to a compact structure, which matches the structural prediction of a trilobal fold. Overall our experiments suggest that calumenin is a Ca2+ sensor, which folds into a compact structure, capable of interacting with its molecular partners, when Ca2+ concentration within the ER reaches the millimolar range. PMID:26991433

  13. Separate cis-trans Pathways Post-transcriptionally Regulate Murine CD154 (CD40 Ligand) Expression

    PubMed Central

    Hamilton, B. JoNell; Wang, Xiao-Wei; Collins, Jane; Bloch, Donald; Bergeron, Alan; Henry, Brian; Terry, Benjamin M.; Zan, Moe; Mouland, Andrew J.; Rigby, William F. C.

    2008-01-01

    We report a role for CA repeats in the 3′-untranslated region (3′-UTR) in regulating CD154 expression. Human CD154 is encoded by an unstable mRNA; this instability is conferred in cis by a portion of its 3′-UTR that includes a polypyrimidine-rich region and CA dinucleotide repeat. We demonstrate similar instability activity with the murine CD154 3′-UTR. This instability element mapped solely to a conserved 100-base CU-rich region alone, which we call a CU-rich response element. Surprisingly, the CA dinucleotide-rich region also regulated reporter expression but at the level of translation. This activity was associated with poly(A) tail shortening and regulated by heterogeneous nuclear ribonucleoprotein L levels. We conclude that the CD154 3′-UTR contains dual cis-acting elements, one of which defines a novel function for exonic CA dinucleotide repeats. These findings suggest a mechanism for the association of 3′-UTR CA-rich response element polymorphisms with CD154 overexpression and the subsequent risk of autoimmune disease. PMID:18640985

  14. Aluminum Chloride Induces Osteoblasts Apoptosis via Disrupting Calcium Homeostasis and Activating Ca(2+)/CaMKII Signal Pathway.

    PubMed

    Cao, Zheng; Liu, Dawei; Zhang, Qiuyue; Sun, Xudong; Li, Yanfei

    2016-02-01

    Aluminum promotes osteoblast (OB) apoptosis. Apoptosis is induced by the disordered calcium homeostasis. Therefore, to investigate the relationship between Al-induced OB apoptosis and calcium homeostasis, calvarium OBs from neonatal rats (3-4 days) were cultured and exposed to 0.048-mg/mL Al(3+) or 0.048-mg/mL Al(3+) combined with 5 μM BAPTA-AM (OBs were pretreated with 5 μM BAPTA-AM for 1 h, then added 0.048 mg/mL Al(3+)), respectively. Then OB apoptosis rate, intracellular calcium ions concentration ([Ca(2+)]i), mRNA expression level of calmodulin (CaM), and protein expression levels of CaM and p-CaMKII in OBs were examined. The result showed that AlCl3 increased OB apoptosis rate, and [Ca(2+)]i and p-CaMKII expression levels and decreased CaM expression levels, whereas BAPTA-AM relieved the effects. These results proved that AlCl3 induced OB apoptosis by disrupting the intracellular Ca(2+) homeostasis and activating the Ca(2+)/CaMKII signal pathway. Our findings can provide new insights for revealing the apoptosis mechanism of OBs exposed to AlCl3.

  15. Using grouper fish as bio-indicator of Cd, Cu, Pb and V in the vicinity of a single buoy mooring (SBM3) at Mina Al Fahal in the Sultanate of Oman.

    PubMed

    Abdul-Wahab, S A; Al-Husaini, I S; Rahmalan, A

    2013-12-01

    This paper investigated metal contamination in muscle tissue of the grouper (Epinephelus coioides) in the vicinity of a single buoy mooring (SBM3) at the Sultanate of Oman. The fish samples were analyzed for cadmium (Cd), copper (Cu), lead (Pb) and vanadium (V). The mean concentrations of Cd, Cu, Pb and V in the fish samples were 0.05 ± 0.004, 0.34 ± 0.013, 0.20 ± 0.018 and 0.03 ± 0.006 mg/kg, respectively. The results were compared with the corresponding permissible concentration limits according to the Sultanate of Oman (0.05, 3.28, 0.3 and 1.4 mg/kg for Cd, Cu, Pb and V, respectively) and the European Commission (0.05 mg/kg for Cd and 0.3 mg/kg for Pb). It was found that none of the overall mean metal concentrations exceeded the corresponding Omani legislation or European Commission limits. However, the overall mean concentration of Cd was identical to the maximum permissible limit of 0.05 mg/kg that has been established by both Commissions, and the limits were exceeded for mean Cd levels in fish at two of the six sampling stations at SBM3. In general, this study indicated that the fishes at SBM3 were not highly contaminated with these metals.

  16. Bicarbonate and Ca2+ Sensing Modulators Activate Photoreceptor ROS-GC1 Synergistically

    PubMed Central

    Duda, Teresa; Pertzev, Alexandre; Makino, Clint L.; Sharma, Rameshwar K.

    2016-01-01

    Photoreceptor ROS-GC1, a prototype subfamily member of the membrane guanylate cyclase family, is a central component of phototransduction. It is a single transmembrane-spanning protein, composed of modular blocks. In rods, guanylate cyclase activating proteins (GCAPs) 1 and 2 bind to its juxtamembrane domain (JMD) and the C-terminal extension, respectively, to accelerate cyclic GMP synthesis when Ca2+ levels are low. In cones, the additional expression of the Ca2+-dependent guanylate cyclase activating protein (CD-GCAP) S100B which binds to its C-terminal extension, supports acceleration of cyclic GMP synthesis at high Ca2+ levels. Independent of Ca2+, ROS-GC1 activity is also stimulated directly by bicarbonate binding to the core catalytic domain (CCD). Several enticing molecular features of this transduction system are revealed in the present study. In combination, bicarbonate and Ca2+-dependent modulators raised maximal ROS-GC activity to levels that exceeded the sum of their individual effects. The F514S mutation in ROS-GC1 that causes blindness in type 1 Leber’s congenital amaurosis (LCA) severely reduced basal ROS-GC1 activity. GCAP2 and S100B Ca2+ signaling modes remained functional, while the GCAP1-modulated mode was diminished. Bicarbonate nearly restored basal activity as well as GCAP2- and S100B-stimulated activities of the F514S mutant to normal levels but could not resurrect GCAP1 stimulation. We conclude that GCAP1 and GCAP2 forge distinct pathways through domain-specific modules of ROS-GC1 whereas the S100B and GCAP2 pathways may overlap. The synergistic interlinking of bicarbonate to GCAPs- and S100B-modulated pathways intensifies and tunes the dependence of cyclic GMP synthesis on intracellular Ca2+. Our study challenges the recently proposed GCAP1 and GCAP2 “overlapping” phototransduction model (Peshenko et al., 2015b). PMID:26858600

  17. Technique for cladding of poison sheets for Cd-poisoned moderator

    NASA Astrophysics Data System (ADS)

    Kawai, Masayoshi; Kobayashi, Yoshiji; Miyake, Yasuhiro; Inoue, Hitoshi; Harada, Masahide; Teshigawara, Makoto; Saito, Shigeru; Kikuchi, Kenji; Chiba, Akira; Sakaki, Kazuhiko; Yamamura, Tsutomu; Kurishita, Hiroaki; Konashi, Kenji; Nakajima, Kazutaka

    2005-08-01

    To make use of cadmium (Cd) as a poison structure in the liquid hydrogen moderator, various cladding methods such as explosion, heating up a solder of 70%Cd-30%Zn in Al case, cold spraying and cold rolling as well as HIP method were tested to seek the best fabrication method. Cd could be partially bonded to aluminum (Al) in all cases. The explosion method made a rather rigid bond between Al and Cd but generated a crack on Al plates behind Cd plate. Solder also bonded well with the Al case, although a part of the Al case was dissolved due to a mixture of Zn and Al. A porous Al layer on Cd plate was formed in the cold spray treatment. The applicability of the ultrasonic test is also discussed for the non-destructive defect inspection of the bonded materials.

  18. Structure refinements of members in the brownmillerite solid solution series Ca{sub 2}Al{sub x}(Fe{sub 0.5}Mn{sub 0.5}){sub 2-x}O{sub 5+{delta}} with 1/2{<=}x{<=}4/3

    SciTech Connect

    Stoeber, Stefan; Schorr, Susan; Poellmann, Herbert

    2013-01-15

    Four different brownmillerite solid solutions Ca{sub 2}Al{sub x}(Fe{sub 0.5}Mn{sub 0.5}){sub 2-x}O{sub 5+{delta}} with 1/2{<=}x{<=}4/3 were synthesized by a solid oxide ceramic method. The phases crystallize either in a primitive centered orthorhombic cell with space group Pnma or in a body centered cell with space group I2mb dependent on the aluminum concentration present in the solid solution. Mn{sup 3+} ions occupy exclusively site 4a coordinated by six oxygen anions. Increasing Mn{sup 3+} concentrations cause a remarkable distortion of the octahedron and indirectly of the tetrahedron, resulting in twisted and tilted octahedral layers as well as buckled tetrahedral chains. The influences are discussed on the site 4a of trivalent manganese due to its Jahn-Teller activity, with regard to the occupation of octahedron and tetrahedron with different sized iron and aluminum ions. - Graphical Abstract: The coupled substitution Fe{sup 3+}>Mn{sup 3+}+Fe{sup 3+} <=>2 Al{sup 3+} in brownmillerite phases (Ca{sub 2}(Fe{sub 0.5}Mn{sub 0.5}){sub 2-x}Al{sub x}O{sub 5+{delta}}) changes predominantly their structural properties, which is essential for the hydration performance of the calcium aluminate cement, where brownmillerites occur as clinker phases. Highlights: Black-Right-Pointing-Pointer We present structural data of four Ca-Al-Fe-Mn-brownmillerites. Black-Right-Pointing-Pointer Mn{sup 3+}-ions occupy exclusively the octahedrally coordinated site 0,0,0. Black-Right-Pointing-Pointer Bonds and angles of the octahedrally coordinated site are distorted strongly. Black-Right-Pointing-Pointer Mn{sup 3+}-ions influence indirectly the shape of the tetrahedron. Black-Right-Pointing-Pointer Mn{sup 3+}-ions stabilize Pnma instead of I2mb in Ca-Al-Fe-Mn-brownmillerites.

  19. Inositol 1,4,5-trisphosphate (IP3)-mediated Ca2+ release evoked by metabotropic agonists and backpropagating action potentials in hippocampal CA1 pyramidal neurons