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Sample records for earth doped integrated

  1. Monolithically integrated active waveguides and lasers using rare-earth doped spin-on glass

    SciTech Connect

    Ashby, C.I.H.; Sullivan, C.T.; Vawter, G.A.

    1996-09-01

    This LDRD program No. 3505.230 explored a new approach to monolithic integration of active waveguides and rare-earth solid state lasers directly onto III-V substrates. It involved selectively incorporating rare-earth ions into spin-on glasses (SOGs) that could be solvent cast and then patterned with conventional microelectronic processing. The patterned, rare-earth spin-on glasses (RESOGs) were to be photopumped by laser diodes prefabricated on the wafer and would serve as directly integrated active waveguides and/or rare-earth solid state lasers.

  2. Tunable, rare earth-doped solid state lasers

    DOEpatents

    Emmett, John L.; Jacobs, Ralph R.; Krupke, William F.; Weber, Marvin J.

    1980-01-01

    Laser apparatus comprising combinations of an excimer pump laser and a rare earth-doped solid matrix, utilizing the 5d-4f radiative transition in a rare earth ion to produce visible and ultra-violet laser radiation with high overall efficiency in selected cases and relatively long radiative lifetimes.

  3. Review on dielectric properties of rare earth doped barium titanate

    NASA Astrophysics Data System (ADS)

    Ismail, Fatin Adila; Osman, Rozana Aina Maulat; Idris, Mohd Sobri

    2016-07-01

    Rare earth doped Barium Titanate (BaTiO3) were studied due to high permittivity, excellent electrical properties and have wide usage in various applications. This paper reviewed on the electrical properties of RE doped BaTiO3 (RE: Lanthanum (La), Erbium (Er), Samarium (Sm), Neodymium (Nd), Cerium (Ce)), processing method, phase transition occurred and solid solution range for complete study. Most of the RE doped BaTiO3 downshifted the Curie temperature (TC). Transition temperature also known as Curie temperature, TC where the ceramics had a transition from ferroelectric to a paraelectric phase. In this review, the dielectric constant of La-doped BaTiO3, Er-doped BaTiO3, Sm-doped BaTiO3, Nd-doped BaTiO3 and Ce-doped BaTiO3 had been proved to increase and the transition temperature or also known as TC also lowered down to room temperature as for all the RE doped BaTiO3 except for Er-doped BaTiO3.

  4. Optical properties of rare-earth-doped silicon nanocomposites

    NASA Astrophysics Data System (ADS)

    Hryciw, Aaron Christopher

    Silicon-based light-emitting materials show much promise for integrated photonics applications. In particular, nanocrystalline silicon can exhibit efficient visible emission, though the mechanism of luminescence is still the subject of some controversy. This thesis reports on the optical properties and device applications of silicon nanocomposite thin films with varying characteristics: amorphous and crystalline nanoclusters (NCs), both undoped and doped with rare-earth (RE) elements. Silicon nanocomposite thin films can be prepared by co-evaporation of Si, SiO, and/or SiO2 followed by annealing to induce phase separation. Such films typically exhibit a broad photoluminescence (PL) band centred between ˜600-800 nm. RE-doped a-Si-NC films can exhibit relatively sharp emission in the near infrared, with excitation cross-sections on the order of 10 -16 cm2 due to the sensitisation effect of the Si NCs---an increase in excitation efficiency by over five orders of magnitude compared with typical values for RE-doped SiO2. Er3+ in particular is important due to its emission at 1.5 mum, corresponding to the wavelength of minimum attenuation in conventional silica optical fibres. To demonstrate control over the spectral width and centre wavelength of emission for photonic applications, undoped and RE-doped a-Si-NC films have been incorporated into optical resonator structures (microcavities) with Ag mirrors. For a-Si films, the emission is tunable from 475 to 875 nm, extendable to 1630 nm upon the addition of Er. It is well known that Si NCs are capable of efficient energy transfer to many of the RE3+ ions; the specific nature of the non-radiative transfer process, however, has not been established with certainty. Efficient nanocluster-mediated excitation has been demonstrated for Nd-, Tb-, Dy-, Er-, Tm-, and Yb-doped a-Si-NC films. From luminescence modelling of ensembles of a-Si NCs, the observed quenching with increased annealing temperature can be accounted for by

  5. 40 CFR 721.10423 - Complex strontium aluminate, rare earth doped (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... earth doped (generic). 721.10423 Section 721.10423 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10423 Complex strontium aluminate, rare earth doped... substances identified generically as complex strontium aluminate, rare earth doped (PMNs P-12-22, P-12-23,...

  6. Photoluminescence characteristics of rare earth-doped nanoporous aluminum oxide

    NASA Astrophysics Data System (ADS)

    de Azevedo, W. M.; de Carvalho, D. D.; de Vasconcelos, E. A.; da Silva, E. F.

    2004-07-01

    In this work we present photoluminescence characterization of rare earth ion-doped nanoporous aluminum oxide synthesized by the anodization process in diverse solvents. We find that the luminescence of doped aluminum oxide strongly depends on the synthesis medium. When synthesized in an inorganic acid only rare earth fluorescence is present, whereas nanoporous aluminum oxide synthesized in organic solvent presents two strong unexpected luminescence emission lines, one at 429 nm and the other at 491 nm, with quite long decay time when excited with long wavelength ultraviolet light. The results suggest that light simulation of primary colors and chromaticity control of the emitted light can be done by the a combination of different rare earth ions present in the sample.

  7. Silica-optical-fiber-based rare-earth-doped sensors

    NASA Astrophysics Data System (ADS)

    Sun, Tong; Grattan, Kenneth T. V.; Wade, Scott A.; Forsyth, David

    2001-10-01

    This paper reports on work done with a range of silica fibres, doped with several important rare earth ions such as Er, Nd, Yb and Tm, to create a range of novel optical sensors. The approach reported herein is based on monitoring and analysis of the fluorescence decay from such fibres in the time domain as well as in the frequency domain. With these fibres, temperature sensors operating in the range from as low as -200 degree(s)C to beyond 1000 degree(s)C have been constructed. A temperature resolution of the order of a few degrees Celsius has been typically reported from these types of sensors. Fibre of this type has been used in a simple yet effective structural integrity monitoring system (being incorporated successfully into concrete samples) and an optical fire alarm system with potential applications for engine monitoring has been developed. A further recent discovery is a small level of strain sensitivity in such fibres - this has been explored over the region from 0 to 2000(mu) e, showing a level of resolution better than a few tens of microstrain, and sensors based on this effect are discussed and reported on in this work.

  8. Rare Earth Doped High Temperature Ceramic Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Pal, AnnaMarie; Patton, Martin O.; Jenkins, Phillip P.

    1999-01-01

    As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study develops a spectral emittance model for films of rare earth containing materials. Although there are several possible rare earth doped high temperature materials, this study was confined to rare earth aluminum garnets. Good agreement between experimental and theoretical spectral emittances was found for erbium, thulium and erbium-holmium aluminum garnets. Spectral emittances of these films are sensitive to temperature differences across the film. Emitter efficiency is also a sensitive function of temperature. For thulium aluminum garnet the efficiency is 0.38 at 1700 K but only 0.19 at 1262 K.

  9. Promising wastewater treatment using rare earth-doped nanoferrites

    NASA Astrophysics Data System (ADS)

    Ahmed, M. A.; Bishay, Samiha T.; Khafagy, Rasha M.; Saleh, N. M.

    2014-01-01

    Single-phases of the spinel nanoferrites Zn0.5Co0.5Al0.5R0.04Fe1.46O4; R=Sm, Pr, Ce and La, were synthesized using the flash auto combustion method. X-ray diffraction (XRD) results indicated that doping nanoferrites with small concentrations of rare earth elements (RE) allowed their entrance to the spinel lattice. Transmission electron microscope (TEM) images revealed that doping with different RE elements resulted in the formation of different nanometric shapes such as nanospheres and nanowires. Doping with Sm3+ and Ce3+ resulted in the formation of nanospheres with average diameter of 14 and 30 nm respectively. In addition to the granular nanospheres, doping with Pr3+ and La3+ resulted in the formation of some nanowires with different aspect ratios (average length of ≈100 nm and diameter of ≈9 nm) and (average length of ≈150 nm and outer diameter of ≈22 nm) respectively. At fixed temperature, the Ac conductivity (σ) increased as the RE ionic radius increases except for Ce, due to the role of valance fluctuation from Ce3+ to Ce4+ ions. La- and Pr-doped nanoferrites showed the highest ac conductivity values, which is most probably due to the presence of large numbers of nanowires in these two types of ferrites. For all entire samples, the effective magnetic moment (μeff) decreased, while the Curie temperature (TC) increased as the RE ionic radius increases. The synthesized rare earth nanoferrites showed promising results in purifying colored wastewater. La-doped ferrite was capable for up-taking 92% of the dye content, followed by Pr-doped ferrite, which adsorbed 85% of the dye, while Sm- and Ce-doped ferrites showed lower dye removal efficiency of 80% and 72% respectively. High dye uptake shown by La- and Pr-doped ferrites is most probably due to the presence of nanowires and their higher Ac conductivity values. These excellent results were not previously reported.

  10. Rare earth doped zinc oxide varistors

    DOEpatents

    McMillan, A.D.; Modine, F.A.; Lauf, R.J.; Alim, M.A.; Mahan, G.D.; Bartkowiak, M.

    1998-12-29

    A varistor includes a Bi-free, essentially homogeneous sintered body of a ceramic composition including, expressed as nominal weight %, 0.2--4.0% oxide of at least one rare earth element, 0.5--4.0% Co{sub 3}O{sub 4}, 0.05--0.4% K{sub 2}O, 0.05--0.2% Cr{sub 2}O{sub 3}, 0--0.2% CaO, 0.00005--0.01% Al{sub 2}O{sub 3}, 0--2% MnO, 0--0.05% MgO, 0--0.5% TiO{sub 3}, 0--0.2% SnO{sub 2}, 0--0.02% B{sub 2}O{sub 3}, balance ZnO. 4 figs.

  11. Rare earth doped zinc oxide varistors

    DOEpatents

    McMillan, April D.; Modine, Frank A.; Lauf, Robert J.; Alim, Mohammad A.; Mahan, Gerald D.; Bartkowiak, Miroslaw

    1998-01-01

    A varistor includes a Bi-free, essentially homogeneous sintered body of a ceramic composition including, expressed as nominal weight %, 0.2-4.0% oxide of at least one rare earth element, 0.5-4.0% Co.sub.3 O.sub.4, 0.05-0.4% K.sub.2 O, 0.05-0.2% Cr.sub.2 O.sub.3, 0-0.2% CaO, 0.00005-0.01% Al.sub.2 O.sub.3, 0-2% MnO, 0-0.05% MgO, 0-0.5% TiO.sub.3, 0-0.2% SnO.sub.2, 0-0.02% B.sub.2 O.sub.3, balance ZnO.

  12. Oxidation Effects in Rare Earth Doped Topological Insulator Thin Films.

    PubMed

    Figueroa, A I; van der Laan, G; Harrison, S E; Cibin, G; Hesjedal, T

    2016-01-01

    The breaking of time-reversal symmetry (TRS) in topological insulators is a prerequisite for unlocking their exotic properties and for observing the quantum anomalous Hall effect (QAHE). The incorporation of dopants which exhibit magnetic long-range order is the most promising approach for TRS-breaking. REBiTe3, wherein 50% of the Bi is substitutionally replaced by a RE atom (RE = Gd, Dy, and Ho), is a predicted QAHE system. Despite the low solubility of REs in bulk crystals of a few %, highly doped thin films have been demonstrated, which are free of secondary phases and of high crystalline quality. Here we study the effects of exposure to atmosphere of rare earth-doped Bi2(Se, Te)3 thin films using x-ray absorption spectroscopy. We demonstrate that these RE dopants are all trivalent and effectively substitute for Bi(3+) in the Bi2(Se, Te)3 matrix. We find an unexpected high degree of sample oxidation for the most highly doped samples, which is not restricted to the surface of the films. In the low-doping limit, the RE-doped films mostly show surface oxidation, which can be prevented by surface passivation, encapsulation, or in-situ cleaving to recover the topological surface state. PMID:26956771

  13. Oxidation Effects in Rare Earth Doped Topological Insulator Thin Films

    PubMed Central

    Figueroa, A. I.; van der Laan, G.; Harrison, S. E.; Cibin, G.; Hesjedal, T.

    2016-01-01

    The breaking of time-reversal symmetry (TRS) in topological insulators is a prerequisite for unlocking their exotic properties and for observing the quantum anomalous Hall effect (QAHE). The incorporation of dopants which exhibit magnetic long-range order is the most promising approach for TRS-breaking. REBiTe3, wherein 50% of the Bi is substitutionally replaced by a RE atom (RE = Gd, Dy, and Ho), is a predicted QAHE system. Despite the low solubility of REs in bulk crystals of a few %, highly doped thin films have been demonstrated, which are free of secondary phases and of high crystalline quality. Here we study the effects of exposure to atmosphere of rare earth-doped Bi2(Se, Te)3 thin films using x-ray absorption spectroscopy. We demonstrate that these RE dopants are all trivalent and effectively substitute for Bi3+ in the Bi2(Se, Te)3 matrix. We find an unexpected high degree of sample oxidation for the most highly doped samples, which is not restricted to the surface of the films. In the low-doping limit, the RE-doped films mostly show surface oxidation, which can be prevented by surface passivation, encapsulation, or in-situ cleaving to recover the topological surface state. PMID:26956771

  14. Spectroscopic studies of Yb3+-doped rare earth orthosilicate crystals

    NASA Astrophysics Data System (ADS)

    Campos, S.; Denoyer, A.; Jandl, S.; Viana, B.; Vivien, D.; Loiseau, P.; Ferrand, B.

    2004-06-01

    Infrared transmission and Raman scattering have been used to study Raman active phonons and crystal-field excitations in Yb3+-doped yttrium, lutetium and scandium orthosilicate crystals (Y2SiO5 (YSO), Lu2SiO5 (LSO) and Sc2SiO5 (SSO)), which belong to the same C2h6 crystallographic space group. Energy levels of the Yb3+ ion 2F5/2 manifold are presented. In the three hosts, Yb3+ ions experience high crystal field strength, particularly in Yb:SSO. Satellites in the infrared transmission spectra have been detected for the first time in the Yb3+-doped rare earth orthosilicates. They could be attributed to perturbed Yb3+ sites of the lattices or to magnetically coupled Yb3+ pairs.

  15. Rare Earth Doped Magnetic Clusters of Gold for Medical Application

    NASA Astrophysics Data System (ADS)

    Yadav, Brahm Deo; Kumar, Vijay

    2011-03-01

    In recent years gold clusters have been studied extensively due to their unusual properties and applications in cancer treatment and catalysis. Small gold clusters having up to 15 atoms are planar as shown in figure 1. Thereafter a transition occurs to 3D structures but the atomic structures continue to have high dispersion. Doping of these clusters could transform them in to new structures and affect the properties. Gold clusters with cage structures such as W@Au12 can be prepared with large highest occupied-lowest unoccupied molecular orbital (HOMO-LUMO) gap by doping with a transition metal atom such as W. By changing the transition metal atom, cage structures of different sizes as well as different HOMO-LUMO gaps can be formed which could be useful in different optical applications. In these structures gold clusters are generally non-magnetic. However, it is also possible to form magnetic clusters of gold such as Gold clusters have been found to be good for cancer treatment. We have performed ab initio calculations on doping of rare earths in small gold clusters to obtain magnetic clusters using projector augmented wave pseudopotential method within generalized gradient approximation for the exchange-correlation energy. Elemental gold clusters having up to 15 atoms are planar and thereafter 3D structures become favorable. We have explored the changes in the growth behavior when a rare earth atom is doped and studied the variation in the magnetic behavior as a function of size. Our results suggest that gold clusters may have twin advantage of treating cancer as well as be helful in magnetic imaging such as by MRI.

  16. Rare Earth Doped Yttrium Aluminum Garnet (YAG) Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Pal, AnnaMarie T.; Patton, Martin O.; Jenkins, Phillip P.

    1999-01-01

    As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study presents a spectral emittance model for films and cylinders of rare earth doped yttrium aluminum garnets. Good agreement between experimental and theoretical film spectral emittances was found for erbium and holmium aluminum garnets. Spectral emittances of films are sensitive to temperature differences across the film. For operating conditions of interest, the film emitter experiences a linear temperature variation whereas the cylinder emitter has a more advantageous uniform temperature. Emitter efficiency is also a sensitive function of temperature. For holminum aluminum garnet film the efficiency is 0.35 at 1446K but only 0.27 at 1270 K.

  17. Multicomponent, Rare-Earth-Doped Thermal-Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Miller, Robert A.; Zhu, Dongming

    2005-01-01

    Multicomponent, rare-earth-doped, perovskite-type thermal-barrier coating materials have been developed in an effort to obtain lower thermal conductivity, greater phase stability, and greater high-temperature capability, relative to those of the prior thermal-barrier coating material of choice, which is yttria-partially stabilized zirconia. As used here, "thermal-barrier coatings" (TBCs) denotes thin ceramic layers used to insulate air-cooled metallic components of heat engines (e.g., gas turbines) from hot gases. These layers are generally fabricated by plasma spraying or physical vapor deposition of the TBC materials onto the metal components. A TBC as deposited has some porosity, which is desirable in that it reduces the thermal conductivity below the intrinsic thermal conductivity of the fully dense form of the material. Undesirably, the thermal conductivity gradually increases because the porosity gradually decreases as a consequence of sintering during high-temperature service. Because of these and other considerations such as phase transformations, the maximum allowable service temperature for yttria-partially stabilized zirconia TBCs lies in the range of about 1,200 to 1,300 C. In contrast, the present multicomponent, rare-earth-doped, perovskite-type TBCs can withstand higher temperatures.

  18. White light emission from GaN stack layers doped by different rare-earth metals

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Liu, Chang

    2015-02-01

    Experimental progress of electroluminescence devices (ELDs) employing GaN doped with rare-earth metals had been significantly made targeting RGB displays. However, reports on the theoretical models to design the devices and the applications were limited. Our previous paper proposed a device model using the quantum collision theory and Judd-Ofelt approximation to design the ELDs for white light illumination. In the present study, the model is modified by considering the light extraction efficiency and optical loss during propagating in the films. To improve the luminous efficiency, an ELD with three stack layers of GaN:Tm/GaN:Er/GaN:Eu is proposed and designed. The model predicts that the color of the integrated light can be controlled by applied voltage, thickness of each doping layer and doping concentrations of the rare earth metals. The luminous efficacy of white light emission at a bias of -100 V is calculated to be 274 lm/W, which is much higher than that of fluorescent lumps. The proposed ELD will open a door to efficient solid-state lighting.

  19. Earth System Oxygenation: Toward an Integrated Theory of Earth Evolution

    NASA Astrophysics Data System (ADS)

    Anbar, A. D.

    2015-12-01

    considered as possible drivers of surface redox evolution, but typically in isolation. We are tackling the grand challenge of developing an integrated theory of Earth evolution, grounded in the physics of a cooling planet, and motivated by the implications for chemical evolution of the biosphere. The framework of such a theory will be presented.

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

    SciTech Connect

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

    2012-06-15

    The effect of partial substitution of alkaline earth (AE) ions, Sr{sup 2+} and Ca{sup 2+}, for the rare earth (RE) ions, La{sup 3+}, Ce{sup 3+}, Pr{sup 3+}, and Sm{sup 3+}, on the physical properties of REVO{sub 4} compounds were investigated. The use of the Pechini method to synthesize the vanadates allowed for high levels of AE substitution to be obtained. Coulometric titration was used to measure redox isotherms for these materials and showed that the addition of the AE ions increased both reducibility and electronic conductivity under typical solid oxide fuel cell (SOFC) anode conditions, through the formation of compounds with mixed vanadium valence. In spite of their high electronic conductivity, REVO{sub 4}-yttira stabilized zirconia (YSZ) composite anodes exhibited only modest performance when used in SOFCs operating with H{sub 2} fuel at 973 K due to their low catalytic activity. High performance was obtained, however, after the addition of a small amount of catalytically active Pd to the anode. - Graphical abstract: Coulometric titration isotherms for ({open_square}) LaVO{sub 4}, ( White-Circle ) PrVO{sub 4}, ( Lozenge ) CeVO{sub 4}, ( Black-Up-Pointing-Triangle ) Ce{sub 0.7}Sr{sub 0.3}VO{sub 3.85}, and ( Black-Square ) Ce{sub 0.7}Ca{sub 0.3}VO{sub 3.85}, at 973 K. Highlights: Black-Right-Pointing-Pointer Infiltration procedures were used to prepare SOFC anodes from various vanadates. Black-Right-Pointing-Pointer Doping of Alkaline Earth to Rare Earth Vanadates showed to improve conductivity and chemical stability. Black-Right-Pointing-Pointer Alkaline Earth Doped Rare Earth Vanadates-YSZ composites showed conductivities as high as 5 S cm{sup -1} at 973 K. Black-Right-Pointing-Pointer As with other ceramic anodes, the addition of a catalyst was required to achieve low anode impedance.

  1. Health Sensing Functions in Thermal Barrier Coatings Incorporating Rare-Earth-Doped Luminescent Sublayers

    NASA Technical Reports Server (NTRS)

    Eldridge, J. I.; Singh, J.; Wolfe, D. E.

    2004-01-01

    Great effort has been directed towards developing techniques to monitor the health of thermal barrier coatings (TBCs) that would detect the approach of safety-threatening conditions. An unconventional approach is presented here where health sensing functionality is integrated into the TBC itself by the incorporation of rare-earth-doped luminescent sublayers to monitor erosion as well as whether the TBC is maintaining the underlying substrate at a sufficiently low temperature. Erosion indication is demonstrated in electron-beam physical vapor deposited (EB-PVD) TBCs consisting of 7wt% yttria-stabilized zirconia (7YSZ) with europium-doped and terbium-doped sublayers. Multiple ingot deposition produced sharp boundaries between the doped sublayers without interrupting the columnar growth of the TBC. The TBC-coated specimens were subjected to alumina particle jet erosion, and the erosion depth was then indicated under ultraviolet illumination that excited easily visible luminescence characteristic of sublayer that was exposed by erosion. In addition, temperature measurements from a bottom-lying europium-doped sublayer in a TBC produced by multiple ingot EB-PVD were accomplished by measuring the temperature-dependent decay time from the 606 nm wavelength emission excited in that sublayer with a 532 nm wavelength laser that was selected for its close match to one of the europium excitation wavelengths as well as being at a wavelength where the TBC is relatively transparent. It is proposed the low dopant levels and absence of interruption of the TBC columnar growth allow the addition of the erosion and temperature sensing functions with minimal effects on TBC performance.

  2. Energetics of Rare Earth Doped Uranium Oxide Solid Solutions

    NASA Astrophysics Data System (ADS)

    Zhang, Lei

    The physical and chemical properties of UO2 nuclear fuels are affected as fission products accumulate during irradiation. The lanthanides, a main group of fission products, form extensive solid solutions with uranium oxide in the fluorite structure. Thermodynamic studies of such solid solutions had been performed to obtain partial molar free energies of oxygen as a function of dopant concentration and temperature; however, direct measurement of formation enthalpies was hampered by the refractory nature of these oxides. In this work, high temperature oxide melt solution calorimetry was utilized to study the thermochemistry of various rare earth doped uranium oxide LnxU 1-xO2-0.5x+y (Ln = La, Y, Nd) over a wide range of dopant concentrations and oxygen contents. The sintered solid solutions were carefully characterized to determine their phase purity, chemical composition, and uranium oxidation state, with most of the materials in the oxygen excess regime. The enthalpies of formation of LnxU1-xO2-0.5x+y were calculated from the calorimetric data. The oxidation enthalpies of these solid solutions are similar to that of UO2. The formation enthalpies from constituent oxides (LnO1.5, UO2, and UO3) become increasingly negative with addition of dopant cations and appear relatively independent of the uranium oxidation state (oxygen content) when the type and concentration of the dopants are the same. This is valid in the oxygen excess regime; thus an estimation of formation enthalpies of LnxU1-xO2 materials can be made. The formation enthalpies from elements of hyperstoichiometric LnxU1-xO 2-0.5x+y materials obtained from calorimetric measurements are in good agreement with those calculated from free energy data. A direct comparison between the formation enthalpies from calorimetric study and computational research using density functional theory was also performed. The experimental and computational energies of LnxU 1-xO2 (Ln = La, Y, Nd) generally agree within 10 k

  3. Integrated Instrument Simulator Suites for Earth Science

    NASA Technical Reports Server (NTRS)

    Tanelli, Simone; Tao, Wei-Kuo; Matsui, Toshihisa; Hostetler, Chris; Hair, Johnathan; Butler, Carolyn; Kuo, Kwo-Sen; Niamsuwan, Noppasin; Johnson, Michael P.; Jacob, Joseph C.; Tsang, Leung; Shams, Khawaja; Jaruwatanadilok, Sermsak; Oveisgharan, Shadi; Simard, Marc; Turk, Francis J.

    2012-01-01

    The NASA Earth Observing System Simulators Suite (NEOS3) is a modular framework of forward simulations tools for remote sensing of Earth's Atmosphere from space. It was initiated as the Instrument Simulator Suite for Atmospheric Remote Sensing (ISSARS) under the NASA Advanced Information Systems Technology (AIST) program of the Earth Science Technology Office (ESTO) to enable science users to perform simulations based on advanced atmospheric and simple land surface models, and to rapidly integrate in a broad framework any experimental or innovative tools that they may have developed in this context. The name was changed to NEOS3 when the project was expanded to include more advanced modeling tools for the surface contributions, accounting for scattering and emission properties of layered surface (e.g., soil moisture, vegetation, snow and ice, subsurface layers). NEOS3 relies on a web-based graphic user interface, and a three-stage processing strategy to generate simulated measurements. The user has full control over a wide range of customizations both in terms of a priori assumptions and in terms of specific solvers or models used to calculate the measured signals.This presentation will demonstrate the general architecture, the configuration procedures and illustrate some sample products and the fundamental interface requirements for modules candidate for integration.

  4. Sensing Using Rare-Earth-Doped Upconversion Nanoparticles

    PubMed Central

    Hao, Shuwei; Chen, Guanying; Yang, Chunhui

    2013-01-01

    Optical sensing plays an important role in theranostics due to its capability to detect hint biochemical entities or molecular targets as well as to precisely monitor specific fundamental psychological processes. Rare-earth (RE) doped upconversion nanoparticles (UCNPs) are promising for these endeavors due to their unique frequency converting capability; they emit efficient and sharp visible or ultraviolet (UV) luminescence via use of ladder-like energy levels of RE ions when excited at near infrared (NIR) light that are silent to tissues. These features allow not only a high penetration depth in biological tissues but also a high detection sensitivity. Indeed, the energy transfer between UCNPs and biomolecular or chemical indicators provide opportunities for high-sensitive bio- and chemical-sensing. A temperature-sensitive change of the intensity ratio between two close UC bands promises them for use in temperature mapping of a single living cell. In this work, we review recent investigations on using UCNPs for the detection of biomolecules (avidin, ATP, etc.), ions (cyanide, mecury, etc.), small gas molecules (oxygen, carbon dioxide, ammonia, etc.), as well as for in vitro temperature sensing. We also briefly summarize chemical methods in synthesizing UCNPs of high efficiency that are important for the detection limit. PMID:23650480

  5. Sensing using rare-earth-doped upconversion nanoparticles.

    PubMed

    Hao, Shuwei; Chen, Guanying; Yang, Chunhui

    2013-01-01

    Optical sensing plays an important role in theranostics due to its capability to detect hint biochemical entities or molecular targets as well as to precisely monitor specific fundamental psychological processes. Rare-earth (RE) doped upconversion nanoparticles (UCNPs) are promising for these endeavors due to their unique frequency converting capability; they emit efficient and sharp visible or ultraviolet (UV) luminescence via use of ladder-like energy levels of RE ions when excited at near infrared (NIR) light that are silent to tissues. These features allow not only a high penetration depth in biological tissues but also a high detection sensitivity. Indeed, the energy transfer between UCNPs and biomolecular or chemical indicators provide opportunities for high-sensitive bio- and chemical-sensing. A temperature-sensitive change of the intensity ratio between two close UC bands promises them for use in temperature mapping of a single living cell. In this work, we review recent investigations on using UCNPs for the detection of biomolecules (avidin, ATP, etc.), ions (cyanide, mecury, etc.), small gas molecules (oxygen, carbon dioxide, ammonia, etc.), as well as for in vitro temperature sensing. We also briefly summarize chemical methods in synthesizing UCNPs of high efficiency that are important for the detection limit. PMID:23650480

  6. Feasibility of Integrated Insulation in Rammed Earth

    NASA Astrophysics Data System (ADS)

    Stone, C.; Balintova, M.; Holub, M.

    2015-11-01

    Building Codes in Europe stipulate strict thermal performance criteria which any traditional rammed earth recipe cannot meet. This does not infer that the material itself is inferior; it has many other face saving attributes such as low embodied energy, high workability, sound insulation, fire resistance, aesthetics, high diffusivity and thermal accumulation properties. Integrated insulation is experimented with, to try achieve a 0.22 [W/(m2.K)] overall coefficient of heat transfer for walls required by 2015 Slovak standards, without using external insulation or using technologically complex interstitial insulation. This has the added aesthetic benefit of leaving the earth wall exposed to the external environment. Results evaluate the feasibility of this traditional approach.

  7. Multilayer Thermal Barrier Coating (TBC) Architectures Utilizing Rare Earth Doped YSZ and Rare Earth Pyrochlores

    NASA Technical Reports Server (NTRS)

    Schmitt, Michael P.; Rai, Amarendra K.; Bhattacharya, Rabi; Zhu, Dongming; Wolfe, Douglas E.

    2014-01-01

    To allow for increased gas turbine efficiencies, new insulating thermal barrier coatings (TBCs) must be developed to protect the underlying metallic components from higher operating temperatures. This work focused on using rare earth doped (Yb and Gd) yttria stabilized zirconia (t' Low-k) and Gd2Zr2O7 pyrochlores (GZO) combined with novel nanolayered and thick layered microstructures to enable operation beyond the 1200 C stability limit of current 7 wt% yttria stabilized zirconia (7YSZ) coatings. It was observed that the layered system can reduce the thermal conductivity by approximately 45 percent with respect to YSZ after 20 hr of testing at 1316 C. The erosion rate of GZO is shown to be an order to magnitude higher than YSZ and t' Low-k, but this can be reduced by almost 57 percent when utilizing a nanolayered structure. Lastly, the thermal instability of the layered system is investigated and thought is given to optimization of layer thickness.

  8. Origin of enhanced magnetization in rare earth doped multiferroic bismuth ferrite

    SciTech Connect

    Nayek, C.; Thirmal, Ch.; Murugavel, P.; Tamilselvan, A.; Balakumar, S.

    2014-02-21

    We report structural and magnetic properties of rare earth doped Bi{sub 0.95}R{sub 0.05} FeO{sub 3} (R = Y, Ho, and Er) submicron particles. Rare earth doping enhances the magnetization and the magnetization shows an increasing trend with decreasing dopant ionic radii. In contrast to the x-ray diffraction pattern, we have seen a strong evidence for the presence of rare earth iron garnets R{sub 3}Fe{sub 5}O{sub 12} in magnetization measured as a function of temperature, in selected area electron diffraction, and in Raman measurements. Our results emphasised the role of secondary phases in the magnetic property of rare earth doped BiFeO{sub 3} compounds along with the structural distortion favoring spin canting by increase in Dzyaloshinskii-Moriya exchange energy.

  9. Synthesis and Photoresponse of Rare-Earth-Doped Phosphosilicates

    SciTech Connect

    Cao, Z.; Lee, Burtrand I.; Samuels, William D.; Exarhos, Gregory J.

    1998-12-14

    Phosphate ceramics doped with Tb3+ ions were synthesized through Sol-Gel process (SGP). the emission intensity as a function of various factors such as matrix composition, crystal structure, particle size, dopant concentration, and synthesis conditions was investigated.

  10. The integrated Regional Earth System Model

    NASA Astrophysics Data System (ADS)

    Kraucunas, I.; Clarke, L.; Dirks, J.; Hejazi, M. I.; Hibbard, K. A.; Huang, M.; Janetos, A. C.; Kintner-Meyer, M.; Kleese van Dam, K.; Leung, L.; Moss, R. H.; Rice, J.; Scott, M. J.; Thomson, A. M.; West, T. O.; Whitney, P.; Yang, Z.

    2012-12-01

    The integrated Regional Earth System Model (iRESM) is a unique modeling framework being developed at Pacific Northwest National Laboratory (PNNL) to simulate the interactions among natural and human systems at scales relevant to regional decision making. The framework unites high-resolution models of regional climate, hydrology, agriculture, socioeconomics, and energy systems using a flexible software architecture. The framework is portable and can be customized to inform a variety of complex questions and decisions, including (but not limited to) planning, implementation, and evaluation of mitigation and adaptation options across a range of sectors. iRESM also incorporates extensive stakeholder interactions and analysis to inform model development, coupling strategies, and characterization of uncertainties. Ongoing numerical experiments are yielding new insights into the interactions among human and natural systems on regional scales, with an initial focus on the energy-land-water nexus and the penetration of renewable energy technologies in the upper U.S. Midwest. The iRESM framework also is being extended and applied to the U.S. Gulf Coast, with a particular emphasis on how changes in extreme events will affect both coastal in inland energy infrastructure in the region. This talk will focus on iRESM's development and capabilities, initial results from numerical experiments, and the challenges and opportunities associated with integrated regional modeling.

  11. The alkali and alkaline earth metal doped ZnO nanotubes: DFT studies

    NASA Astrophysics Data System (ADS)

    Peyghan, Ali Ahmadi; Noei, Maziar

    2014-01-01

    Doping of several alkali and alkaline earth metals into sidewall of an armchair ZnO nanotube has been investigated by employing the density functional theory in terms of energetic, geometric, and electronic properties. It has been found that doping processes of the alkali and alkaline metals are endothermic and exothermic, respectively. Based on the results, contrary to the alkaline metal doping, the electronic properties of the tube are much more sensitive to alkali metal doping so that it is transformed from intrinsic semiconductor with HOMO-LUMO energy gap of 3.77 eV to an extrinsic semiconductor with the energy gap of ~1.11-1.95 eV. The doping of alkali and alkaline metals increases and decreases the work function of the tube, respectively, which may influence the electron emission from the tube surface.

  12. N-type carbon nanotube by alkaline-earth metal Sr doping

    NASA Astrophysics Data System (ADS)

    Kim, Byung Hoon; Park, Tae Hoi; Baek, Seung Jae; Lee, Dong Su; Park, Seung Joo; Kim, Jun Sung; Park, Yung Woo

    2008-05-01

    Alkaline-earth metal, Sr, was doped on multiwalled carbon nanotubes (MWNTs) by vapor phase reaction method. The tunneling electron microscopy, energy dispersive x ray, and Raman spectroscopy were studied for verifying the Sr doping on MWNT. The temperature-dependent resistivity [ρ(T)] and thermoelectric power [S(T)] were also performed for both pristine MWNT and Sr-doped MWNT (Sr-MWNT). ρ(T ) of Sr-MWNT did not significantly change compared to pristine MWNT. However, S(T ) of Sr-MWNT considerably changes, i.e., it shows n-type behavior in contrast to pristine MWNT.

  13. Influence of rare earth doping on thermoelectric properties of SrTiO{sub 3} ceramics

    SciTech Connect

    Liu, J. Wang, C. L.; Li, Y.; Su, W. B.; Zhu, Y. H.; Li, J. C.; Mei, L. M.

    2013-12-14

    Thermoelectric properties of SrTiO{sub 3} ceramics, doped with different rare earth elements, were investigated in this work. It's found that the ionic radius of doping elements plays an important role on thermoelectric properties: SrTiO{sub 3} ceramics doped with large rare earth ions (such as La, Nd, and Sm) exhibit large power factors, and those doped with small ions (such as Gd, Dy, Er, and Y) exhibit low thermal conductivities. Therefore, a simple approach for enhancing the thermoelectric performance of SrTiO{sub 3} ceramics is proposed: mainly doped with large ions to obtain a large power factor and, simultaneously, slightly co-doped with small ions to obtain a low thermal conductivity. Based on this rule, Sr{sub 0.8}La{sub 0.18}Yb{sub 0.02}TiO{sub 3} ceramics were prepared, whose ZT value at 1 023 K reaches 0.31, increasing by a factor of 19% compared with the single-doped counterpart Sr{sub 0.8}La{sub 0.2}TiO{sub 3} (ZT = 0.26)

  14. Metal enhanced fluorescence in rare earth doped plasmonic core-shell nanoparticles.

    PubMed

    Derom, S; Berthelot, A; Pillonnet, A; Benamara, O; Jurdyc, A M; Girard, C; Colas des Francs, G

    2013-12-13

    We theoretically and numerically investigate metal enhanced fluorescence of plasmonic core-shell nanoparticles doped with rare earth (RE) ions. Particle shape and size are engineered to maximize the average enhancement factor (AEF) of the overall doped shell. We show that the highest enhancement (11 in the visible and 7 in the near-infrared) is achieved by tuning either the dipolar or the quadrupolar particle resonance to the rare earth ion's excitation wavelength. Additionally, the calculated AEFs are compared to experimental data reported in the literature, obtained in similar conditions (plasmon mediated enhancement) or when a metal-RE energy transfer mechanism is involved.

  15. Numerical simulations of the optical gain of crystalline fiber doped by rare earth and transition ion

    NASA Astrophysics Data System (ADS)

    Daoui, A. K.; Boubir, B.; Adouane, A.; Demagh, N.; Ghoumazi, M.

    2015-02-01

    A fiber laser is a laser whose gain medium is a doped fiber, although lasers whose cavity is made wholly of fibers have also been called fiber lasers. The gain media in a fiber laser is usually fiber doped with rare-earth ions, such as erbium (Er), neodymium (Nd), ytterbium (Yb), thulium (Tm), or praseodymium (Pr), which is doped into the core of the optical fiber, similar to those used to transmit telecommunications signals. Fiber lasers find many applications in materials processing, including cutting, welding, drilling, and marking metal. To maximize their market penetration, it is necessary to increase their output power. In this work, we present a detailed study based on the numerical simulation using MATLAB, of one of the principal characteristics of a fiber laser doped with rare earth ions and transition ion. The gain depends on several parameters such as the length of the doped fiber, the density, the pump power, noise, etc.). The used program resolves the state equations in this context together with those governing the light propagation phenomena. The developed code can also be used to study the dynamic operating modes of a doped fiber laser.

  16. Infrared spectroscopy of rare-earth-doped CaFe2As2

    NASA Astrophysics Data System (ADS)

    Xing, Zhen; Huffman, T. J.; Xu, Peng; Qazilbash, M. M.; Saha, S. R.; Drye, Tyler; Paglione, J.

    2014-03-01

    Recently, rare-earth doping in CaFe2As2 has been used to tune its electronic, magnetic, and structural properties. The substitution of rare-earth ions at the alkaline-earth sites leads to the suppression of the spin-density wave (SDW) phase transition in CaFe2As2. For example, Pr substitution results in a paramagnetic metal in the tetragonal phase that is susceptible to a low temperature structural transition to a collapsed tetragonal phase. However, La-doped CaFe2As2 remains in the uncollapsed tetragonal structure down to the lowest measured temperatures. Both the uncollapsed and collapsed tetragonal structures exhibit superconductivity with maximum Tc reaching 47 K, the highest observed in inter-metallics albeit with a small superconducting volume fraction. In this work, we perform ab-plane infrared spectroscopy of rare-earth-doped CaFe2As2 at different cryogenic temperatures. Our aim is to ascertain the contributions of electron doping and chemical pressure to the charge and lattice dynamics of this iron-arsenide system.

  17. Pulsed laser deposition of rare-earth-doped glasses: a step toward lightwave circuits

    NASA Astrophysics Data System (ADS)

    Morea, R.; Fernandez, J.; Balda, R.; Gonzalo, J.

    2016-02-01

    Pulsed Laser Deposition (PLD) is used to produce Er-doped lead-niobium germanate (PbO-Nb2O5-GeO2) and fluorotellurite (TeO2-ZnO-ZnF2) thin film glasses. Films having high refractive index, low absorption and large transmission are obtained in a narrow processing window that depends on the actual PLD configuration (O2 pressure ˜a few Pa, Laser energy density ˜2-3 J cm-2 for the results presented in this work). However, Er-doped thin film glasses synthetized at room temperature using these experimental parameters show poor photoluminescence (PL) performance due to non-radiative decay channels, such as a large OH- concentration. Thermal annealing allows improving PL intensity and lifetime (τPL), the latter becoming close to that of the parent Er-doped bulk glass. In addition, the use of alternate PLD from host glass and rare-earth targets allows the synthesis of nanostructured thin film glasses with a controlled rare-earth concentration and in-depth distribution, as it is illustrated for Er-doped PbO-Nb2O5-GeO2 film glasses. In this case, PL intensity at 1.53 μm increases with the spacing between Er-doped layers to reach a maximum for a separation between Er-doped layers >= 5 nm, while τPL is close to the bulk value independently of the spacing. Finally, the comparison of these results with those obtained for films grown by standard PLD from Er-doped glass targets suggests that nanostructuration allows reducing rare-earth clustering and concentration quenching effects.

  18. Photoluminescence in rare-earth doped As2S3 glasses

    NASA Astrophysics Data System (ADS)

    Iovu, Mihai S.; Andriesh, Andrei M.; Culeac, Ion P.

    2005-02-01

    Chalcogenide glasses doped with various rare-earth ions are extensively studied as potential materials for fiber optic amplifiers operating at 1.3 and 1.5 μm telecommunication windows. The experimental results on optical absorption and photoluminescence of arsenic sulfide glasses and optical fibers doped with rare-earth elements (Pr3+, Sm3+, Er3+ and Dy3+) are presented. Near the absorption edge the rare-earth impurities affect strongly the slope and the magnitude of the week absorption tail. Fluorescence spectra of bulk samples and optical fibers of arsenic sulfide doped with different concentrations of Pr3+ and Dy3+ indicate on the presence of luminescent band located around 1.3 and 1.5 μm. These bands correspond to the electron transitions from the discrete levels (6F7/2&rarr:6H13/2 and 6F5/2&rarr6H11/2 for Dy3+ and 1G4/1&rarr3H6 and 3F3&rarr3H4 for Pr3+, respectively), and which confirmed the presence of trivalent rare-earth ions in the glass matrix. The observed effects of rare-earth dopants on the As2S3 glass are discussed in connection with the expected behavior of the impurities in the glass.

  19. Visible to infrared low temperature photoluminescence of rare earth doped bismuth germanate crystals.

    PubMed

    Canimoglu, A; Ayvacikli, M; Karabulut, Y; Karali, T; Can, N

    2016-05-01

    In this paper, the influence of a series of rare earth (Eu, Tm, Nd) and Cr ion doping on the optical properties of BGO was investigated by means of photoluminescence (PL) from visible to IR region in the 10-300K temperature range using different types of detectors, namely, photomultiplier tube (PMT), InGaAs (IGA), and Si. Several samples were investigated having dopants concentrations of 0.3wt%Nd, 0.4wt%Tm, 0.06wt% Cr and 3ppm Eu. The PL spectra of the samples showed different luminescence behaviour which is assigned to the 4f intra shell transition from rare earth ions. The temperature dependence of the PL from rare earth doped BGO crystals is also examined. PMID:26943903

  20. Electronic structure of rare-earth doped SrFBiS2 superconductors from photoemission spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Mishra, P.; Lohani, H.; Jha, Rajveer; Awana, V. P. S.; Sekhar, B. R.

    2016-06-01

    The electronic structure study of the Rare Earth (La, Ce) doped SrFBiS2 superconductors using valence band photoemission in conjugation with the band structure calculations have been presented. The spectral features shift towards higher binding energy, consistent with the electron doping, for the doped compounds. An enhanced metallicity in addition to the shift in the Fermi level towards the conduction band occurs for the Rare Earth (RE) doped compounds. Further, the degeneracy of bands along X-M direction at valence band maximum (VBM) and conduction band minimum (CBM) is lifted due to RE doping. An enhanced spectral weight near EF accompanied by a decrease in density of states at higher binding energy occurs for the doped compounds. This unusual spectral weight shift is substantiated by the change in Fermi surface topology and reduced distortion of Bi-S plane for the doped compounds.

  1. Creation of trapped electrons and holes in alkaline-earth fluoride crystals doped by rare-earth ions

    NASA Astrophysics Data System (ADS)

    Radzhabov, E.

    2002-06-01

    Defects in Ce 3+- and Eu 2+-doped alkaline-earth fluorides, created by vacuum ultraviolet (VUV) photons with energy lower than that of the band gap, were investigated by various methods: thermostimulated luminescence, photostimulated luminescence and optical absorption. The CaF 2:Eu 2+ thermoluminescence curves in the range of 60-330 K due to various types of trapped holes were the same after VUV illumination as after X-ray irradiation. Thermoluminescence curves of Ce 3+-doped alkaline-earth fluorides created by VUV illumination or X-ray irradiation were generally similar. However, Vk thermoluminescence peaks were absent in VUV-illuminated CaF 2:Ce 3+ and SrF 2:Ce 3+ crystals. Creation of Ce 2+ characteristic bands was observed in photostimulated luminescence spectra as well as in optical absorption spectra of vacuum ultraviolet-illuminated or X-ray-irradiated Ce 3+-doped crystals. The proposed mechanism of creation of trapped hole and trapped electron defects by vacuum ultraviolet illumination involves charge transfer-type transitions, in which the electron transfers from valence band to an impurity level, lying in the band gap. Comparison of all involved energies of transitions in the crystals investigated shows that the sum of all transition energies is less than that of the band gap by 1-3 eV. This energy difference can be considered as the energy of lattice relaxation around created Ce 2+ or Eu + ions.

  2. Design and refinement of rare earth doped multicore fiber lasers

    NASA Astrophysics Data System (ADS)

    Prudenzano, F.; Mescia, L.; Di Tommaso, A.; Surico, M.; De Sario, M.

    2013-09-01

    A novel multicore ytterbium doped fiber laser is designed, with the target of maximizing both the effective mode area and the beam quality, by means of a complete home-made computer code. It can be employed to construct high power and Quasi-Gaussian beam lasers. The novel laser configuration exploits a single mode multicore fiber and does not need Talbot cavity or other in-phase mode selection mechanisms. This is an innovative solution, because to the best of our knowledge, for the first time, we have designed a truly single-mode multicore fiber laser. For comparison we have optimized two other laser configurations which are well known in literature, both employing a multimode multicore fiber and a Talbot cavity as a feedback for the in-phase supermode selection. All three multicore fibers, constituted by the same glass, are doped with the same ytterbium ion concentration and pumped with the same input power. Multimodal fiber lasers exhibit lower beam quality, i.e. a higher beam quality factor M2, with respect to the single mode one, even if suitable Talbot cavities are designed, but they are very competitive when a more compact laser cavity is required for the same output power. The novel single mode nineteen core laser exhibits a simulated effective mode area Aeff = 703 μm2 and a beam quality factor M2 = 1.05, showing better characteristics than the other two lasers.

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

    SciTech Connect

    Dong, Qiang; Yin, Shu; Yoshida, Mizuki; Wu, Xiaoyong; Liu, Bin; Miura, Akira; Takei, Takahiro; Kumada, Nobuhiro; Sato, Tsugio

    2015-09-15

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

  4. Radioluminescence and thermoluminescence of rare earth element and phosphorus-doped zircon

    SciTech Connect

    Karali, T.; Can, N.; Townsend, P.D.; Rowlands, A.P.; Hanchar, J.M.

    2000-06-01

    The radioluminescence and thermoluminescence spectra of synthetic zircon crystals doped with individual trivalent rare earth element (REE) ions (Pr, Sm, Eu, Gd, Dy, Ho, Er, and Yb) and P are reported in the temperature range 25 to 673 K. Although there is some intrinsic UV/blue emission from the host lattice, the dominant signals are from the rare-earth sites, with signals characteristic of the REE{sup 3+} states. The shapes of the glow curves are different for each dopant, and there are distinct differences between glow peak temperatures for different rare-earth lines of the same element. Within the overall set of signals there are indications of linear trends in which some glow peak temperatures vary as a function of the ionic size of the rare earth ions. The temperature shifts of the peaks are considerable, up to 200{degree}, and much larger than those cited in other rare-earth-doped crystals of LaF{sub 3} and Bi{sub 4}Ge{sub 3}O{sub 12}. The data clearly suggest that the rare-earth ions are active both in the trapping and luminescence steps, and hence the TL occurs within localized defect complexes that include REE{sup 3+} ions.

  5. Modification of phonon processes in nanostructured rare-earth-ion-doped crystals

    NASA Astrophysics Data System (ADS)

    Lutz, Thomas; Veissier, Lucile; Thiel, Charles W.; Cone, Rufus L.; Barclay, Paul E.; Tittel, Wolfgang

    2016-07-01

    Nano-structuring impurity-doped crystals affects the phonon density of states and thereby modifies the atomic dynamics induced by interaction with phonons. We propose the use of nano-structured materials in the form of powders or phononic bandgap crystals to enable or improve persistent spectral hole burning and coherence for inhomogeneously broadened absorption lines in rare-earth-ion-doped crystals. This is crucial for applications such as ultra-precise radio-frequency spectrum analyzers and optical quantum memories. As an example, we discuss how phonon engineering can enable spectral hole burning in erbium-doped materials operating in the convenient telecommunication band and present simulations for density of states of nano-sized powders and phononic crystals for the case of Y2SiO5 , a widely used material in current quantum memory research.

  6. Raman spectral analysis of TiO2 thin films doped with rare-earth samarium.

    PubMed

    Yang, Chang-Hu; Ma, Zhong-Quan

    2012-08-01

    TiO(2) thin films doped with rare-earth samarium were prepared on a quartz plate by the sol-gel/spin-coating technique. The samples were annealed at 700 °C to 1100 °C, and the Raman spectra of the samples were obtained. Analyses of Raman spectra show that samarium doping can inhibit the anatase-rutile phase transition. Samarium doping can refine grains of TiO(2) thin films and increase the internal stress, thereby preventing lattice vibration. Nanocrystalline TiO(2) thin films obviously show the phonon confinement effect, i.e., the blueshift of characteristic Raman peak and full width at half-height increase, and the peak shapes asymmetrically broaden with a decrease in the grain sizes of the samples.

  7. Rare Earth Doped Semiconductors and Materials Research Society Symposium Proceedings, Volume 301

    NASA Astrophysics Data System (ADS)

    Ballance, John

    1994-02-01

    The properties of rare earth ions in solids were studied in detail for decades, but until recently this work was restricted to dominantly ionic hosts such as fluorides and oxides, and to a lesser extent to more covalently bonded hosts, such as tetrahedral 2-6 semiconductors. The idea of rare earth elements incorporated into covalent semiconductors such as GaAs and Si may be traced to a short communication in 1963 by R.L. Bell (J. Appl. Phys. 34, 1563 (1963)) proposing a dc-pumped rare earth laser. At about the same time, three unpublished technical reports appeared as a result of U.S. Department of Defense sponsored research in rare earth doped Si, GaAs, and InP to fabricate LED's. Attempts by other researchers to identify sharp 4f specific emissions in these hosts essentially failed.

  8. Capillary-force-induced formation of luminescent polystyrene/(rare-earth-doped nanoparticle) hybrid hollow spheres.

    PubMed

    Chen, Min; Xie, Lin; Li, Fuyou; Zhou, Shuxue; Wu, Limin

    2010-10-01

    This paper presents a "one-pot" procedure to synthesize polystyrene/(rare-earth-doped nanoparticles) (PS/REDNPs) hybrid hollow spheres via the in situ diffusion of organic core into inorganic shell under strong capillary force. In this approach, when carboxyl-capped PS colloids were deposited by different REDNPs in aqueous medium, such as LaF3:Eu3+, LaF3:Ce3+-Tb3+, and YVO4:Dy3+, PS/REDNPs inorganic-organic hybrid hollow spheres could be directly obtained via the in situ diffusion of core PS chains into the voids between rare-earth-doped nanoparticles through the strong capillary force. Not only is the synthetic procedure versatile and very simple, but also the obtained hybrid hollow spheres are hydrophilic and luminescent and could be directly used in chemical and biological fields.

  9. Thermoelectric Properties of Barium Plumbate Doped by Alkaline Earth Oxides

    NASA Astrophysics Data System (ADS)

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

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

  10. Optical properties of rare earth doped strontium aluminate (SAO) phosphors: A review

    NASA Astrophysics Data System (ADS)

    Kshatri, D. S.; Khare, A.

    2014-11-01

    After the first news on rare earth (RE) doped strontium aluminate (SAO) phosphors in late 1990s, researchers all over the world geared up to develop stable and efficient persistent phosphors. Scientists studied various features of long lasting phosphors (LLP) and tried to earmark appropriate mechanism. However, about two decades after the discovery of SrAl2O4: Eu2+, Dy3+, the number of persistent luminescent materials is not significant. In this review, we present an overview of the optical characteristics of RE doped SAO phosphors in terms of photoluminescence (PL), thermoluminescence (TL) and afterglow spectra. Also, we refresh the work undertaken to study diverse factors like dopant concentration, temperature, surface energy, role of activator, etc. Simultaneously, some of our important findings on SAO are reported and discussed in the end.

  11. Influence of doping with alkaline earth metals on the optical properties of thermochromic VO2

    NASA Astrophysics Data System (ADS)

    Dietrich, Marc K.; Kramm, Benedikt G.; Becker, Martin; Meyer, Bruno K.; Polity, Angelika; Klar, Peter J.

    2015-05-01

    Thin films of doped VO2 were deposited, analyzed, and optimized with regard to their solar energy transmittance (Tsol) and visible/luminous light transmittance (Tlum) which are important parameters in the context of smart window applications in buildings. The doping with alkaline earth metals (AEM) like Mg, Ca, Sr, or Ba increased both Tsol and Tlum due to a bandgap widening and an associated absorption edge blue-shift. Thereby, the brown-yellowish color impression of pure VO2 thin films, which is one major hindrance limiting the usage of VO2 as thermochromic window coating, was overcome. Transparent thin films with excellent switching behavior were prepared by sputtering. Highly doped V1-xMexO2 (Me = Ca, Sr, Ba) kept its excellent thermochromic switching behavior up to x(Me) = Me/(Me + V) = 10 at. % doping level, while the optical bandgap energy was increased from 1.64 eV for undoped VO2 to 2.38 eV for x(Mg) = 7.7 at. %, 1.85 eV for x(Ca) = 7.4 at. %, 1.84 eV for x(Sr) = 6.4 at. % and 1.70 eV for x(Ba) = 6.8 at. %, as well as the absorption edge is blue shifted by increasing AEM contents. Also, the critical temperature ϑc, at which the semiconductor-to-metal transition (SMT) occurs, was decreased by AEM doping, which amounted to about -0.5 K/at. % for all AEM on average. The critical temperature was determined by transmittance-temperature hysteresis measurements. Furthermore, Tsol and Tlum were calculated and were found to be significantly enhanced by AEM doping. Tlum increased from 32.0% in undoped VO2 to 43.4% in VO2 doped with 6.4 at. % Sr. Similar improvements were found for other AEM. The modulation of the solar energy transmittance ΔTsol, which is the difference of the Tsol values in the low and high temperature phase, was almost constant or even slightly increased when the doping level was increased up to about 10 at. % Ca, Sr, or Ba.

  12. Google Maps and Google Earth Integration Using KML

    NASA Astrophysics Data System (ADS)

    Ricket, D.

    2006-12-01

    Google Maps, which offers a powerful, user-friendly mapping technology that provides an easy-to-use platform for representing geographic information. Integration between the Google Maps API and Google Earth is now possible using KML. The possibilities this presents for scientific and other geographic datasets will be presented.

  13. Fabrication and characterization of rare earth doped wide bandgap semiconductors for spectral storage

    NASA Astrophysics Data System (ADS)

    Sly, Mohamed Fawzy

    Powder samples of MgS and CaS, singly doped with Eu and doubly doped with Eu and Ce, were synthesized for their usage in spectral storage. Thin films of these materials were fabricated using the pulsed laser deposition (PLD) technique. This fast and simple technique is superior to the single crystal growth or molecular beam epitaxy (MBE) as far as the storage material requirements are concerned. High optical quality films of MgS:Eu and CaS:Eu have been grown and tested. Polycrystalline powder samples of MgS and CaS were synthesized using high temperature reduction of commercially available magnesium and calcium sulfates. These materials were singly doped with rare earth lanthanides using high temperature diffusion in powder forms. Rare earth lanthanide impurities in very small concentrations are necessary for optical applications such as spectral storage for which all the materials prepared during the course of this study were made. Thin films of rare earth doped calcium and magnesium sulfides have been produced by using pulsed laser deposition (PLD) technique. Coating of the reactive surfaces of the PLD chamber with SiC has been performed to make them resistant to the corrosive environment and the by products of the deposition process. Solid targets needed for thin films were fabricated from the synthesized polycrystalline powders by high-pressure cold compression technique. Deposition of thin films of CaS and MgS has been performed and to protect these films from the environment, capping layers of aluminum oxide (Al2O 3) or ZnS have been deposited over the CaS and MgS thin films. In magnesium sulfide, oxygen doped magnesium sulfide and calcium sulfides, europium centers occur in different spectral regions. Therefore, multi-layer thin film structures were fabricated to allow for higher density of spectral storage. Various characterization techniques such as optical microscopy, X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy have

  14. Fibre Tip Sensors for Localised Temperature Sensing Based on Rare Earth-Doped Glass Coatings

    PubMed Central

    Schartner, Erik P.; Monro, Tanya M.

    2014-01-01

    We report the development of a point temperature sensor, based on monitoring upconversion emission from erbium:ytterbium-doped tellurite coatings on the tips of optical fibres. The dip coating technique allows multiple sensors to be fabricated simultaneously, while confining the temperature-sensitive region to a localised region on the end-face of the fibre. The strong response of the rare earth ions to changing temperature allows a resolution of 0.1–0.3 °C to be recorded over the biologically relevant range of temperatures from 23–39 °C. PMID:25407907

  15. Rare earth elements in synthetic zircon. 1. synthesis, and rare earth element and phosphorus doping.

    SciTech Connect

    Hanchar, J. M.; Finch, R. J.; Hoskin, W. O.; Watson, E. B.; Cherniak, D. J.; Mariano, A. N.; Chemical Engineering; George Washington Univ.; Univ. of Canterbury; Australian National Univ.; Rensselaer Polytechnic Inst.

    2001-05-01

    Sedimentary mineral assemblages commonly contain detrital zircon crystals as part of the heavy-mineral fraction. Age spectra determined by U-Pb isotopic analysis of single zircon crystals within a sample may directly image the age composition--but not the chemical composition--of the source region. Rare earth element (REE) abundances have been measured for zircons from a range of common crustal igneous rock types from different tectonic environments, as well as kimberlite, carbonatite, and high-grade metamorphic rocks, to assess the potential of using zircon REE characteristics to infer the rock types present in sediment source regions. Except for zircon with probable mantle affinities, zircon REE abundances and normalized patterns show little intersample and intrasample variation. To evaluate the actual variation in detrital zircon REE composition in a true sediment of known mixed provenance, zircons from a sandstone sample from the Statfjord Formation (North Sea) were analyzed. Despite a provenance including high-grade metasediment and granitoids and a range in zircon age of 2.82 b.y., the zircon REEs exhibit a narrow abundance range with no systematic differences in pattern shape. These evidences show zircon REE patterns and abundances are generally not useful as indicators of provenance.

  16. Nanophotonic coherent light–matter interfaces based on rare-earth-doped crystals

    PubMed Central

    Zhong, Tian; Kindem, Jonathan M.; Miyazono, Evan; Faraon, Andrei

    2015-01-01

    Quantum light–matter interfaces connecting stationary qubits to photons will enable optical networks for quantum communications, precise global time keeping, photon switching and studies of fundamental physics. Rare-earth-ion-doped crystals are state-of-the-art materials for optical quantum memories and quantum transducers between optical photons, microwave photons and spin waves. Here we demonstrate coupling of an ensemble of neodymium rare-earth-ions to photonic nanocavities fabricated in the yttrium orthosilicate host crystal. Cavity quantum electrodynamics effects including Purcell enhancement (F=42) and dipole-induced transparency are observed on the highly coherent 4I9/2–4F3/2 optical transition. Fluctuations in the cavity transmission due to statistical fine structure of the atomic density are measured, indicating operation at the quantum level. Coherent optical control of cavity-coupled rare-earth ions is performed via photon echoes. Long optical coherence times (T2∼100 μs) and small inhomogeneous broadening are measured for the cavity-coupled rare-earth ions, thus demonstrating their potential for on-chip scalable quantum light–matter interfaces. PMID:26364586

  17. Nanophotonic coherent light-matter interfaces based on rare-earth-doped crystals.

    PubMed

    Zhong, Tian; Kindem, Jonathan M; Miyazono, Evan; Faraon, Andrei

    2015-01-01

    Quantum light-matter interfaces connecting stationary qubits to photons will enable optical networks for quantum communications, precise global time keeping, photon switching and studies of fundamental physics. Rare-earth-ion-doped crystals are state-of-the-art materials for optical quantum memories and quantum transducers between optical photons, microwave photons and spin waves. Here we demonstrate coupling of an ensemble of neodymium rare-earth-ions to photonic nanocavities fabricated in the yttrium orthosilicate host crystal. Cavity quantum electrodynamics effects including Purcell enhancement (F=42) and dipole-induced transparency are observed on the highly coherent (4)I(9/2)-(4)F(3/2) optical transition. Fluctuations in the cavity transmission due to statistical fine structure of the atomic density are measured, indicating operation at the quantum level. Coherent optical control of cavity-coupled rare-earth ions is performed via photon echoes. Long optical coherence times (T2∼100 μs) and small inhomogeneous broadening are measured for the cavity-coupled rare-earth ions, thus demonstrating their potential for on-chip scalable quantum light-matter interfaces. PMID:26364586

  18. Nanophotonic coherent light-matter interfaces based on rare-earth-doped crystals.

    PubMed

    Zhong, Tian; Kindem, Jonathan M; Miyazono, Evan; Faraon, Andrei

    2015-09-14

    Quantum light-matter interfaces connecting stationary qubits to photons will enable optical networks for quantum communications, precise global time keeping, photon switching and studies of fundamental physics. Rare-earth-ion-doped crystals are state-of-the-art materials for optical quantum memories and quantum transducers between optical photons, microwave photons and spin waves. Here we demonstrate coupling of an ensemble of neodymium rare-earth-ions to photonic nanocavities fabricated in the yttrium orthosilicate host crystal. Cavity quantum electrodynamics effects including Purcell enhancement (F=42) and dipole-induced transparency are observed on the highly coherent (4)I(9/2)-(4)F(3/2) optical transition. Fluctuations in the cavity transmission due to statistical fine structure of the atomic density are measured, indicating operation at the quantum level. Coherent optical control of cavity-coupled rare-earth ions is performed via photon echoes. Long optical coherence times (T2∼100 μs) and small inhomogeneous broadening are measured for the cavity-coupled rare-earth ions, thus demonstrating their potential for on-chip scalable quantum light-matter interfaces.

  19. Synthesis of rare earth doped TiO2 nanorods as photocatalysts for lignin degradation.

    PubMed

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; Moon, Ji-Won; Gu, Baohua; Wang, Wei

    2015-10-28

    A two-step process is developed to synthesize rare earth doped titania nanorods (RE-TiO2 NRs) as photocatalysts for efficient degradation of lignin under simulated sunlight irradiation. In this approach, protonated titanate nanotubes with layered structures were first prepared by a hydrothermal approach, and rare earth metal ions were subsequently bound to the negatively charged surface of the synthesized titanate via electrostatic incorporation. The as-synthesized RE-TiO2 NRs after calcination generally showed much higher photocatalytic efficiencies than those of undoped TiO2 NRs or the commercial P25 TiO2 photocatalyst. Using methyl orange (MO) as a probing molecule, we demonstrate that Eu-TiO2 NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10(-3) s(-1). The La(3+), Sm(3+), Eu(3+) and Er(3+) doped TiO2 NRs also showed higher photocatalytic efficiencies in degrading MO than the commercial P25 TiO2. We further demonstrate that lignin can be photodegraded effectively and rapidly at room temperature under simulated sunlight through two reaction routes, which could be important in controlling ways of lignin depolymerization or the formation of reaction products. PMID:26400095

  20. Synthesis of rare earth doped TiO2 nanorods as photocatalysts for lignin degradation

    DOE PAGES

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; Moon, Ji-Won; Gu, Baohua; Wang, Wei

    2015-09-10

    In this paper, a two-step process is developed to synthesize rare earth doped titania nanorods (RE–TiO2 NRs) as photocatalysts for efficient degradation of lignin under simulated sunlight irradiation. In this approach, protonated titanate nanotubes with layered structures were first prepared by a hydrothermal approach, and rare earth metal ions were subsequently bound to the negatively charged surface of the synthesized titanate via electrostatic incorporation. The as-synthesized RE–TiO2 NRs after calcination generally showed much higher photocatalytic efficiencies than those of undoped TiO2 NRs or the commercial P25 TiO2 photocatalyst. Using methyl orange (MO) as a probing molecule, we demonstrate that Eu–TiO2more » NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10-3 s-1. The La3+, Sm3+, Eu3+ and Er3+ doped TiO2 NRs also showed higher photocatalytic efficiencies in degrading MO than the commercial P25 TiO2. Finally, we further demonstrate that lignin can be photodegraded effectively and rapidly at room temperature under simulated sunlight through two reaction routes, which could be important in controlling ways of lignin depolymerization or the formation of reaction products.« less

  1. Synthesis of rare earth doped TiO2 nanorods as photocatalysts for lignin degradation.

    PubMed

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; Moon, Ji-Won; Gu, Baohua; Wang, Wei

    2015-10-28

    A two-step process is developed to synthesize rare earth doped titania nanorods (RE-TiO2 NRs) as photocatalysts for efficient degradation of lignin under simulated sunlight irradiation. In this approach, protonated titanate nanotubes with layered structures were first prepared by a hydrothermal approach, and rare earth metal ions were subsequently bound to the negatively charged surface of the synthesized titanate via electrostatic incorporation. The as-synthesized RE-TiO2 NRs after calcination generally showed much higher photocatalytic efficiencies than those of undoped TiO2 NRs or the commercial P25 TiO2 photocatalyst. Using methyl orange (MO) as a probing molecule, we demonstrate that Eu-TiO2 NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10(-3) s(-1). The La(3+), Sm(3+), Eu(3+) and Er(3+) doped TiO2 NRs also showed higher photocatalytic efficiencies in degrading MO than the commercial P25 TiO2. We further demonstrate that lignin can be photodegraded effectively and rapidly at room temperature under simulated sunlight through two reaction routes, which could be important in controlling ways of lignin depolymerization or the formation of reaction products.

  2. Integrating the Earth, Atmospheric, and Ocean Sciences at Millersville University

    NASA Astrophysics Data System (ADS)

    Clark, R. D.

    2005-12-01

    For nearly 40 years, the Department of Earth Sciences at Millersville University (MU-DES) of Pennsylvania has been preparing students for careers in the earth, atmospheric, and ocean sciences by providing a rigorous and comprehensive curricula leading to B.S. degrees in geology, meteorology, and oceanography. Undergraduate research is a hallmark of these earth sciences programs with over 30 students participating in some form of meritorious research each year. These programs are rich in applied physics, couched in mathematics, and steeped in technical computing and computer languages. Our success is measured by the number of students that find meaningful careers or go on to earn graduate degrees in their respective fields, as well as the high quality of faculty that the department has retained over the years. Student retention rates in the major have steadily increased with the introduction of a formal learning community and peer mentoring initiatives, and the number of new incoming freshmen and transfer students stands at an all-time high. Yet until recently, the disciplines have remained largely disparate with only minor inroads made into integrating courses that seek to address the Earth as a system. This is soon to change as the MU-DES unveils a new program leading to a B.S. in Integrated Earth Systems. The B.S. in Integrated Earth Systems (ISS) is not a reorganization of existing courses to form a marketable program. Instead, it is a fully integrated program two years in development that borrows from the multi-disciplinary backgrounds and experiences of faculty, while bringing in resources that are tailored to visualizing and modeling the Earth system. The result is the creation of a cross-cutting curriculum designed to prepare the 21st century student for the challenges and opportunities attending the holistic study of the Earth as a system. MU-DES will continue to offer programs leading to degrees in geology, meteorology, and ocean science, but in addition

  3. Power scaling estimate of crystalline fiber waveguides with rare earth doped YAG cores

    NASA Astrophysics Data System (ADS)

    Li, Da; Hong, Pengda; Meissner, Stephanie K.; Meissner, Helmuth E.

    2016-03-01

    Power scaling analysis based on the model by Dawson et al. [1,2] for circular core fibers has been applied to estimating power scaling of crystalline fiber waveguides (CFWs) with RE3+ doped single crystalline or ceramic YAG (RE=rare earth: Yb, Er, Tm and Ho). Power scaling limits include stimulated Brillouin scattering, thermal lensing effect, and limits to coupling of pump light into CFWs. The CFW designs we have considered consist, in general, of a square doped RE3+:YAG core, an inner cladding of either undoped or laser-inactive-ion-doped YAG and an outer cladding of sapphire. The presented data have been developed for the structures fabricated using the Adhesive-Free Bonding (AFB®) technique, but the results should be essentially independent of fabrication technique, assuming perfect core/inner cladding/outer cladding interfaces. Hard power scaling limits exist for a specific CFW design and are strongly based on the physical constants of the material and its spectroscopic specifics. For example, power scaling limit was determined as ~16 kW for 2.5% ceramic Yb:YAG/YAG (core material/inner cladding material) at fiber length of 1.7 m and core diameter of 69 μm. Considering the present manufacturing limit for CFW length to be, e.g., 0.5 m, the actual maximum output power will be limited to ~4.4 kW for a Yb:YAG/YAG CFW. Power limit estimates have also been computed for Er3+, Tm3+ and Ho3+doped core based CFWs.

  4. Rare-earth metal oxide doped transparent mesoporous silica plates under non-aqueous condition as a potential UV sensor.

    PubMed

    Lee, Sang-Joon; Park, Sung Soo; Lee, Sang Hyun; Hong, Sang-Hyun; Ha, Chang-Sik

    2013-11-01

    Transparent mesoporous silica plates doped with rare-earth metal oxide were prepared using solvent-evaporation method based on the self-organization between structure-directing agent and silicate in a non-aqueous solvent. A triblock copolymer, Pluronic (F127 or P123), was used as the structure-directing agent, while tetraethyl orthosilicate (TEOS) was used as a silica source. The pore diameter and the surface area of the mesoporous silica plate prepared with the optimized conditions were ca 40 A and 600 m2 g(-1), respectively, for both structure-directing agent. Rare-earth metal oxides (Eu, Tb, Tm oxide) in mesochannel were formed via one-step synthetic route based on the preparation method of a silica plate. Optical properties of rare-earth metal oxide-doped mesoporous silica plates were investigated by UV irradiation and photoluminescence (PL) spectroscopy. Under the exitation wavelength of 254 nm, the doped mesoporous silica plates emitted red, green and blue for Eu, Tb and Tm oxides, respectively. Rare-earth metal oxide-doped mesoporous silica plates showed enhanced PL intensity compared to that of the bulk rare-earth metal oxide.

  5. NOAA's Global Earth Observation - Integrated Data Environment (GEO-IDE)

    NASA Astrophysics Data System (ADS)

    McDonald, K. R.

    2007-12-01

    The international Group on Earth Observation (GEO) and the U.S. coordination group, USGEO, have identified nine societal benefit areas that require environmental data of a wide range of types and from many diverse sources. GEO has called on the nations of the world to ensure that the relevant data that they hold is made accessible and useful to these applications. In response, nations and their environmental agencies are addressing the challenges associated with data integration of these distributed and diverse data types. The National Oceanic and Atmospheric Administration (NOAA) holds extremely large collections of data describing the physical and biological properties of the Earth's environment. To date, the data collections and the systems that support them have been acquired by individually funded and managed programs with differing requirements, standards, interfaces and conventions, mirroring the data integration issues faced at the national and international level. The Global Earth Observation - Integrated Data Environment (GEO-IDE) has been initiated by NOAA to address these issues for its own interdisciplinary applications as well as those of the the broader national and international iniatives. The concept and initial plans for GEO-IDE have been developed by the Data Management Integration Team (DMIT), a group of data management professionals representing all NOAA's Line Offices, Goal Teams and the office of the CIO. The goal of GEO-IDE is to define an architecture and the associated processes necessary to establish the required standards and guidelines that allow NOAA's data providers to make their products available as a set of interoperable services. GEO-IDE is addressing the integration of existing data services while at the same time providing guidance to future data system development activities. It is intended to meet an important NOAA need while also supporting NOAA's contribution to USGEO and GEO.

  6. The integrated Earth System Model Version 1: formulation and functionality

    SciTech Connect

    Collins, William D.; Craig, Anthony P.; Truesdale, John E.; Di Vittorio, Alan; Jones, Andrew D.; Bond-Lamberty, Benjamin; Calvin, Katherine V.; Edmonds, James A.; Kim, Son H.; Thomson, Allison M.; Patel, Pralit L.; Zhou, Yuyu; Mao, Jiafu; Shi, Xiaoying; Thornton, Peter E.; Chini, Louise M.; Hurtt, George C.

    2015-07-23

    The integrated Earth System Model (iESM) has been developed as a new tool for pro- jecting the joint human/climate system. The iESM is based upon coupling an Integrated Assessment Model (IAM) and an Earth System Model (ESM) into a common modeling in- frastructure. IAMs are the primary tool for describing the human–Earth system, including the sources of global greenhouse gases (GHGs) and short-lived species, land use and land cover change, and other resource-related drivers of anthropogenic climate change. ESMs are the primary scientific tools for examining the physical, chemical, and biogeochemical impacts of human-induced changes to the climate system. The iESM project integrates the economic and human dimension modeling of an IAM and a fully coupled ESM within a sin- gle simulation system while maintaining the separability of each model if needed. Both IAM and ESM codes are developed and used by large communities and have been extensively applied in recent national and international climate assessments. By introducing heretofore- omitted feedbacks between natural and societal drivers, we can improve scientific under- standing of the human–Earth system dynamics. Potential applications include studies of the interactions and feedbacks leading to the timing, scale, and geographic distribution of emissions trajectories and other human influences, corresponding climate effects, and the subsequent impacts of a changing climate on human and natural systems. This paper de- scribes the formulation, requirements, implementation, testing, and resulting functionality of the first version of the iESM released to the global climate community.

  7. The integrated Earth system model version 1: formulation and functionality

    DOE PAGES

    Collins, W. D.; Craig, A. P.; Truesdale, J. E.; Di Vittorio, A. V.; Jones, A. D.; Bond-Lamberty, B.; Calvin, K. V.; Edmonds, J. A.; Kim, S. H.; Thomson, A. M.; et al

    2015-07-23

    The integrated Earth system model (iESM) has been developed as a new tool for projecting the joint human/climate system. The iESM is based upon coupling an integrated assessment model (IAM) and an Earth system model (ESM) into a common modeling infrastructure. IAMs are the primary tool for describing the human–Earth system, including the sources of global greenhouse gases (GHGs) and short-lived species (SLS), land use and land cover change (LULCC), and other resource-related drivers of anthropogenic climate change. ESMs are the primary scientific tools for examining the physical, chemical, and biogeochemical impacts of human-induced changes to the climate system. Themore » iESM project integrates the economic and human-dimension modeling of an IAM and a fully coupled ESM within a single simulation system while maintaining the separability of each model if needed. Both IAM and ESM codes are developed and used by large communities and have been extensively applied in recent national and international climate assessments. By introducing heretofore-omitted feedbacks between natural and societal drivers, we can improve scientific understanding of the human–Earth system dynamics. Potential applications include studies of the interactions and feedbacks leading to the timing, scale, and geographic distribution of emissions trajectories and other human influences, corresponding climate effects, and the subsequent impacts of a changing climate on human and natural systems. This paper describes the formulation, requirements, implementation, testing, and resulting functionality of the first version of the iESM released to the global climate community.« less

  8. Oxides doped with rare-earth ions as a recording medium with multiple rewriting

    NASA Astrophysics Data System (ADS)

    Zimenko, Vladislav I.; Petrov, Viacheslav V.; Kravets, Vasyliy G.; Motuz, Vasily V.; Prygun, Alexander V.; Yanchuk, N. E.

    1997-02-01

    The optical memory on materials having the properties of electron trapping is a new direction at development of information storage and rewrite. Currently are pursued investigations directed on creation of a new type recording medium with the opportunity of information rewrite by optical methods as well as a medium for heteroassociative memory in optical neural systems. Primarily as such medium are used alkaline-earth metal sulphides activated by two rare-earth elements. When creating the memory on materials with electron trapping on the basis of alkaline-earth sulphides there arises a number of difficulties: (1) these materials are chemically unstable, especially they are subject to the action of water vapors; (2) films prepared by electron-beam evaporation technique have a polycrystalline structure with grain sizes in the order of 20 nm what has an essential influence on the signal-to-noise ratio at information reading. The main objective which is pursued by us consists in investigating the optical properties of new synthesized materials having the electron trapping properties which are characterized by chemical stability and are easy manufacture at preparation of amorphous structures. We have also recommended to use CaO (MgO) doped with Eu, Sm. It has known, that the optical stimulated luminescence (OSL) obtains in CaO. But OSL appears in the special prepared structures with defects. For this aim there are some methods: thermochemical reduction or radiation processing by electron beam. Besides that the OSL obtains only by nitrogen temperature (77 K).

  9. Spectroscopic studies of copper doped alkaline earth lead zinc phosphate glasses

    NASA Astrophysics Data System (ADS)

    Sastry, S. Sreehari; Rao, B. Rupa Venkateswara

    2014-02-01

    In this paper spectroscopic investigation of Cu2+ doped alkaline earth lead zinc phosphate glasses was done through the spectroscopic techniques like X-ray diffraction, Ultra Violet (UV) absorption Spectroscopy, Electron Paramagnetic Resonance (EPR - X band), Fourier Transform Infra Red (FTIR) and Raman Spectroscopy. Alkaline earth lead zinc phosphate glasses containing 0.1% copper oxide (CuO) were prepared by the melt quenching technique. Spectroscopic studies indicated that there is a greater possibility for the copper ions to exist in Cu2+ state in these glasses. The optical absorption spectra indicated that the absorption peak of Cu2+ is a function of composition. The maxima absorption peak was reported at 862 nm for strontium lead zinc phosphate glass. Bonding parameters were calculated for the optical and EPR data. All these spectral results indicated clearly that there are certain structural changes in the present glass system with different alkaline earth contents. The IR and Raman spectra noticed the breaking of the P-O-P bonds and creating more number of new P-O-Cu bonds.

  10. The EPOS Architecture: Integrated Services for solid Earth Science

    NASA Astrophysics Data System (ADS)

    Cocco, Massimo; Consortium, Epos

    2013-04-01

    The European Plate Observing System (EPOS) represents a scientific vision and an IT approach in which innovative multidisciplinary research is made possible for a better understanding of the physical processes controlling earthquakes, volcanic eruptions, unrest episodes and tsunamis as well as those driving tectonics and Earth surface dynamics. EPOS has a long-term plan to facilitate integrated use of data, models and facilities from existing (but also new) distributed research infrastructures, for solid Earth science. One primary purpose of EPOS is to take full advantage of the new e-science opportunities coming available. The aim is to obtain an efficient and comprehensive multidisciplinary research platform for the Earth sciences in Europe. The EPOS preparatory phase (EPOS PP), funded by the European Commission within the Capacities program, started on November 1st 2010 and it has completed its first two years of activity. EPOS is presently mid-way through its preparatory phase and to date it has achieved all the objectives, milestones and deliverables planned in its roadmap towards construction. The EPOS mission is to integrate the existing research infrastructures (RIs) in solid Earth science warranting increased accessibility and usability of multidisciplinary data from monitoring networks, laboratory experiments and computational simulations. This is expected to enhance worldwide interoperability in the Earth Sciences and establish a leading, integrated European infrastructure offering services to researchers and other stakeholders. The Preparatory Phase aims at leveraging the project to the level of maturity required to implement the EPOS construction phase, with a defined legal structure, detailed technical planning and financial plan. We will present the EPOS architecture, which relies on the integration of the main outcomes from legal, governance and financial work following the strategic EPOS roadmap and according to the technical work done during the

  11. Photon-pair source with controllable delay based on shaped inhomogeneous broadening of rare-earth-metal-doped solids

    SciTech Connect

    Sekatski, Pavel; Sangouard, Nicolas; Gisin, Nicolas; Afzelius, Mikael; Riedmatten, Hugues de

    2011-05-15

    Spontaneous Raman emission in atomic gases provides an attractive source of photon pairs with a controllable delay. We show how this technique can be implemented in solid state systems by appropriately shaping the inhomogeneous broadening. Our proposal is eminently feasible with current technology and provides a realistic solution to entangle remote rare-earth-metal-doped solids in a heralded way.

  12. Improving the intensity and efficiency of compressed echo in rare-earth-ion-doped crystal

    NASA Astrophysics Data System (ADS)

    Xiu-Rong, Ma; Yu-Qing, Liang; Song, Wang; Shuang-Gen, Zhang; Yun-Long, Shan

    2016-07-01

    We investigate the intensity and efficiency of a compressed echo, which is important in arbitrary waveform generation (AWG). A new model of compressed echo is proposed based on the optical Bloch equations, which exposes much more detailed parameters than the conventional model, such as the time delay of the chirp lasers, the nature of the rare-earth-ion-doped crystal, etc. According to the novel model of compressed echo, we find that reducing the time delay of the chirp lasers and scanning the lasers around the center frequency of the inhomogeneously broadened spectrum, while utilizing a crystal with larger coherence time and excitation lifetime can improve the compressed echo’s intensity and efficiency. The theoretical analysis is validated by numerical simulations. Project supported by Special Funds for Scientific and Technological Innovation Projects in Tianjin, China (Grant No. 10FDZDGX00400) and the Tianjin Research Program of Application Foundation and Advanced Technology, China (Grant No. 15JCQNJC01100).

  13. Compensation for effects of ambient temperature on rare-earth doped fiber optic thermometer

    NASA Technical Reports Server (NTRS)

    Adamovsky, G.; Sotomayor, J. L.; Krasowski, M. J.; Eustace, J. G.

    1990-01-01

    Variations in ambient temperature have a negative effect on the performance of any fiber optic sensing system. A change in ambient temperature may alter the design parameters of fiber optic cables, connectors, sources, detectors, and other fiber optic components and eventually the performance of the entire system. The thermal stability of components is especially important in a system which employs intensity modulated sensors. Several referencing schemes have been developed to account for the variable losses that occur within the system. However, none of these conventional compensating techniques can be used to stabilize the thermal drift of the light source in a system based on the spectral properties of the sensor material. The compensation for changes in ambient temperature becomes especially important in fiber optic thermometers doped with rare earths. Different approaches to solving this problem are searched and analyzed.

  14. Compensation for effects of ambient temperature on rare-earth doped fiber optic thermometer

    NASA Technical Reports Server (NTRS)

    Adamovsky, G.; Sotomayor, J. L.; Krasowski, M. J.; Eustace, J. G.

    1989-01-01

    Variations in ambient temperature have a negative effect on the performance of any fiber optic sensing system. A change in ambient temperature may alter the design parameters of fiber optic cables, connectors, sources, detectors, and other fiber optic components and eventually the performance of the entire system. The thermal stability of components is especially important in a system which employs intensity modulated sensors. Several referencing schemes have been developed to account for the variable losses that occur within the system. However, none of these conventional compensating techniques can be used to stabilize the thermal drift of the light source in a system based on the spectral properties of the sensor material. The compensation for changes in ambient temperature becomes especially important in fiber optic thermometers doped with rare earths. Different approaches to solving this problem are searched and analyzed.

  15. Improving the intensity and efficiency of compressed echo in rare-earth-ion-doped crystal

    NASA Astrophysics Data System (ADS)

    Xiu-Rong, Ma; Yu-Qing, Liang; Song, Wang; Shuang-Gen, Zhang; Yun-Long, Shan

    2016-07-01

    We investigate the intensity and efficiency of a compressed echo, which is important in arbitrary waveform generation (AWG). A new model of compressed echo is proposed based on the optical Bloch equations, which exposes much more detailed parameters than the conventional model, such as the time delay of the chirp lasers, the nature of the rare-earth-ion-doped crystal, etc. According to the novel model of compressed echo, we find that reducing the time delay of the chirp lasers and scanning the lasers around the center frequency of the inhomogeneously broadened spectrum, while utilizing a crystal with larger coherence time and excitation lifetime can improve the compressed echo’s intensity and efficiency. The theoretical analysis is validated by numerical simulations. Project supported by Special Funds for Scientific and Technological Innovation Projects in Tianjin, China (Grant No. 10FDZDGX00400) and the Tianjin Research Program of Application Foundation and Advanced Technology, China (Grant No. 15JCQNJC01100).

  16. Spectroscopic analyses of trivalent rare-earth ions doped in different host materials

    NASA Astrophysics Data System (ADS)

    Chandrasekharan, Sreerenjini

    2011-12-01

    Trivalent rare-earth (RE3+) ions of 4f n electronic configurations are found to possess potential applications in the field of optoelectronic and biophotonic technologies owing to their unique optical properties. They have been used as optical activators in a large number of solid-state laser host materials due to their rich energy level structure. This work focuses on the spectroscopic study of two RE 3+ ions, namely, trivalent erbium and neodymium (Er3+ and Nd3+, respectively), embedded in some important single crystal and nanocrystalline host materials including yttrium orthoaluminate (YAlO3), erbium oxide (Er2O3), yttrium oxide (Y2O3) and a combined host system of Y2O 3 and a vinyl polymer named Polymethyl Methacrylate (PMMA). Each one of these host materials are known to be unique for their characteristic properties such as chemical durability, thermal stability, optical clarity, wide band gaps, biocompatibility, and success as phosphors in various optoelectronic devices. The complete material characterization has been performed through morphology analyses using advanced microscopy techniques and spectroscopic analyses of the characteristic absorption and emission spectra by applying phenomenological crystal-field splitting and Judd-Ofelt techniques. The important spectroscopic parameters such as line strengths, radiative decay rates, and branching ratios have been obtained for the intermanifold transitions from the upper multiplets to the corresponding lower-lying multiplet manifolds 2S+1LJ of RE3+ ions doped in various host systems. Using the radiative decay rates, radiative life times are obtained and the experimental analyses of the fluorescent spectra yield the measured lifetimes of emitting metastable states. Finally, the results are compared with the previously published set of values for the same ions doped in similar type of host systems. Detailed analyses of the spectroscopic properties show that the studied systems RE3+ doped single crystals and

  17. Synthesis and thermoluminescence properties of rare earth-doped NaMgBO3 phosphor.

    PubMed

    Khan, Z S; Ingale, N B; Omanwar, S K

    2016-05-01

    Rare earth (Dy(3+) and Sm(3+))-doped sodium magnesium borate (NaMgBO3) is synthesized by solution combustion synthesis method keeping their thermoluminescence properties in mind. The reaction produced very stable crystalline NaMgBO3:RE (RE = Dy(3+), Sm(3+)) phosphors. The phosphors are exposed to (60)Co gamma-ray radiations dose of varying rate from 5 to 25 Gy, and their TL characteristics with kinetic parameters are studied. NaMgBO3:Dy(3+) phosphor shows two peaks for lower doping concentration of Dy(3+) while it reduced to single peak for the higher concentrations of activator Dy(3+). NaMgBO3:Dy(3+) shows the major glow peak around 200 °C while NaMgBO3:Sm(3+) phosphors show two well-separated glow peaks at 200 and 332 °C respectively. The thermoluminescence intensity of these phosphors was compare with the commercially available TLD-100 (Harshaw) phosphor. The TL responses for gamma-ray radiations dose were found to be linear from 5 to 25 Gy for both phosphors while the fading in each case is calculated for the tenure of 45 days.

  18. Coherency strain enhanced dielectric-temperature property of rare-earth doped BaTiO{sub 3}

    SciTech Connect

    Jeon, Sang-Chae; Kang, Suk-Joong L.

    2013-03-18

    Core/shell-grained BaTiO{sub 3} samples were prepared with addition of rare earth elements. The core/shell interface was semi-coherent, and many misfit dislocations formed in Dy-doped samples. In contrast, a coherent interface and few dislocations were observed in Ho- and Er-doped samples. Dy-doped samples exhibited poor temperature stability, showing a peak with no frequency dispersion. Ho- and Er-doped samples exhibited a broad curve with frequency dispersion. This improved temperature stability is attributed to the coherency strain, which leads to the formation of polar nano-regions in the shell. Coherency at the core/shell interface is critical to improve the temperature stability of core/shell-structured BaTiO{sub 3}.

  19. Phase Transformation and Lattice Parameter Changes of Trivalent Rare Earth Doped YSZ as a Function of Temperature

    NASA Astrophysics Data System (ADS)

    Jiang, S. L.; Huang, X.; He, Z.

    2016-09-01

    Yttria-stabilized zirconia (YSZ) co-doped with trivalent oxide Sc2O3 and Yb2O3 is prepared using mechanical alloying and high-temperature sintering. High-temperature XRD analysis was performed to study the phase transformation and lattice parameter changes of various phases in the baseline YSZ and co-doped samples. The results show that the structure for the co-doped samples tends to be more thermally stable at test temperature above critical value. The lattice parameters for all samples increase with temperature at which XRD is carried out, and the lattice parameters for the two trivalent rare earth oxides co-doped YSZ are smaller than that for 7YSZ under the same temperature.

  20. An OpenEarth Framework (OEF) for Integrating and Visualizing Earth Science Data

    NASA Astrophysics Data System (ADS)

    Moreland, J. L.; Nadeau, D. R.; Baru, C.; Crosby, C. J.

    2009-12-01

    The integration of data is essential to make transformative progress in understanding the complex processes operating at the Earth’s surface and within its interior. While our current ability to collect massive amounts of data, develop structural models, and generate high-resolution dynamics models is well developed, our ability to quantitatively integrate these data and models into holistic interpretations of Earth systems is poorly developed. We lack the basic tools to realize a first-order goal in Earth science of developing integrated 4D models of Earth structure and processes using a complete range of available constraints, at a time when the research agenda of major efforts such as EarthScope demand such a capability. Among the challenges to 3D data integration are data that may be in different coordinate spaces, units, value ranges, file formats, and data structures. While several file format standards exist, they are infrequently or incorrectly used. Metadata is often missing, misleading, or relegated to README text files along side the data. This leaves much of the work to integrate data bogged down by simple data management tasks. The OpenEarth Framework (OEF) being developed by GEON addresses these data management difficulties. The software incorporates file format parsers, data interpretation heuristics, user interfaces to prompt for missing information, and visualization techniques to merge data into a common visual model. The OEF’s data access libraries parse formal and de facto standard file formats and map their data into a common data model. The software handles file format quirks, storage details, caching, local and remote file access, and web service protocol handling. Heuristics are used to determine coordinate spaces, units, and other key data features. Where multiple data structure, naming, and file organization conventions exist, those heuristics check for each convention’s use to find a high confidence interpretation of the data. When

  1. The OpenEarth Framework (OEF) for the 3D Visualization of Integrated Earth Science Data

    NASA Astrophysics Data System (ADS)

    Nadeau, David; Moreland, John; Baru, Chaitan; Crosby, Chris

    2010-05-01

    Data integration is increasingly important as we strive to combine data from disparate sources and assemble better models of the complex processes operating at the Earth's surface and within its interior. These data are often large, multi-dimensional, and subject to differing conventions for data structures, file formats, coordinate spaces, and units of measure. When visualized, these data require differing, and sometimes conflicting, conventions for visual representations, dimensionality, symbology, and interaction. All of this makes the visualization of integrated Earth science data particularly difficult. The OpenEarth Framework (OEF) is an open-source data integration and visualization suite of applications and libraries being developed by the GEON project at the University of California, San Diego, USA. Funded by the NSF, the project is leveraging virtual globe technology from NASA's WorldWind to create interactive 3D visualization tools that combine and layer data from a wide variety of sources to create a holistic view of features at, above, and beneath the Earth's surface. The OEF architecture is open, cross-platform, modular, and based upon Java. The OEF's modular approach to software architecture yields an array of mix-and-match software components for assembling custom applications. Available modules support file format handling, web service communications, data management, user interaction, and 3D visualization. File parsers handle a variety of formal and de facto standard file formats used in the field. Each one imports data into a general-purpose common data model supporting multidimensional regular and irregular grids, topography, feature geometry, and more. Data within these data models may be manipulated, combined, reprojected, and visualized. The OEF's visualization features support a variety of conventional and new visualization techniques for looking at topography, tomography, point clouds, imagery, maps, and feature geometry. 3D data such as

  2. An alternative experimental approach to produce rare-earth-doped SiOx films

    NASA Astrophysics Data System (ADS)

    Zanatta, A. R.

    2016-04-01

    Rare-earth (RE) doped silicon-oxide (SiOx) films were prepared by sputtering a combined Si + RE2O3 target with argon ions. The study comprised the neodymium (Nd) and samarium (Sm) rare-earth species and the Si + RE2O3 targets were obtained by partially covering a solid disc of Si with area-defined thin layers of Nd2O3 or Sm2O3 powders. The films were investigated by energy-dispersive x-ray, Raman scattering, optical transmission, and photo-luminescence measurements. According to the experimental results, in the as-deposited form, the films were amorphous and presented RE and oxygen concentrations that scaled with the RE2O3 target area. Additional compositional-structural changes were obtained by thermal annealing the films under a flow of oxygen. Within these changes, one can mention: increase of oxygen concentration, optical bandgap widening, partial Si crystallization, and the development of RE-related light emission. The main aspects associated to the production and structural-optical properties of the films, as determined either by the deposition conditions or by the annealing treatments, are presented and discussed in detail.

  3. Motivational and social cognitive predictors of doping intentions in elite sports: an integrated approach.

    PubMed

    Barkoukis, V; Lazuras, L; Tsorbatzoudis, H; Rodafinos, A

    2013-10-01

    Doping use is an important issue in both competitive and non-competitive sports, and poses potentially irreversible health consequences to users. Scholars increasingly call for theory-driven studies on the psychosocial processes underlying doping use that will inform subsequent policy-making and prevention interventions. The aim of the study was to implement an integrative theoretical model to assess the direct and indirect effects of motivational variables, moral orientations, and social cognitions on doping intentions. A randomly selected and representative sample of 750 elite athletes anonymously completed a battery of questionnaires on motivational and moral constructs, and social cognitions related to doping. Hierarchical linear regression analysis and multiple mediation modeling were used. The effects of achievement goals and moral orientations were significantly mediated by attitudinal, normative, and self-efficacy beliefs, in both lifetime ever and never doping users. Moral orientations indirectly predicted the doping intentions of never users, but did not predict ever users' doping intentions. Achievement goals and sportspersonship orientations influence doping intentions indirectly, through the effects of attitudes and self-efficacy beliefs. Sportspersonship (moral) orientations were relevant to doping intentions among athletes with no prior experiences with doping, while achievement goals and situational temptation were relevant to both lifetime never and ever dopers.

  4. Integrating LiDAR Data into Earth Science Education

    NASA Astrophysics Data System (ADS)

    Robinson, S. E.; Arrowsmith, R.; de Groot, R. M.; Crosby, C. J.; Whitesides, A. S.; Colunga, J.

    2010-12-01

    The use of high-resolution topography derived from Light Detection and Ranging (LiDAR) in the study of active tectonics is widespread and has become an indispensable tool to better understand earthquake hazards. For this reason and the spectacular representation of the phenomena the data provide, it is appropriate to integrate these data into the Earth science education curriculum. A collaboration between Arizona State University, the OpenTopography Facility, and the Southern California Earthquake Center are developing, three earth science education products to inform students and other audiences about LiDAR and its application to active tectonics research. First, a 10-minute introductory video titled LiDAR: Illuminating Earthquakes was produced and is freely available online through the OpenTopography portal and SCEC. The second product is an update and enhancement of the Wallace Creek Interpretive Trail website (www.scec.org/wallacecreek). LiDAR topography data products have been added along with the development of a virtual tour of the offset channels at Wallace Creek using the B4 LiDAR data within the Google Earth environment. The virtual tour to Wallace Creek is designed as a lab activity for introductory undergraduate geology courses to increase understanding of earthquake hazards through exploration of the dramatic offset created by the San Andreas Fault (SAF) at Wallace Creek and Global Positioning System-derived displacements spanning the SAF at Wallace Creek . This activity is currently being tested in courses at Arizona State University. The goal of the assessment is to measure student understanding of plate tectonics and earthquakes after completing the activity. Including high-resolution topography LiDAR data into the earth science education curriculum promotes understanding of plate tectonics, faults, and other topics related to earthquake hazards.

  5. Progress in rare-earth-doped nanocrystalline glass-ceramics for laser cooling

    NASA Astrophysics Data System (ADS)

    Venkata Krishnaiah, Kummara; Ledemi, Yannick; Soares de Lima Filho, Elton; Loranger, Sebastien; Nemova, Galina; Messaddeq, Younes; Kashyap, Raman

    2016-03-01

    Laser cooling with anti-Stokes fluorescencewas predicted by Pringsheim in 1929, but for solids was only demonstrated in 1995. There are many difficulties which have hindered laser assisted cooling, principally the chemical purity of a sample and the availability of suitable hosts. Recent progress has seen the cooled temperature plummet to 93K in Yb:YLF. One of the challenges for laser cooling to become ubiquitous, is incorporating the rare-earthcooling ion in a more easily engineered material, rather than a pure crystalline host. Rare-earth-doped nanocrystalline glass-ceramics were first developed by Wang and Ohwaki for enhanced luminescence and mechanical properties compared to their parent glasses. Our work has focused on creating a nanocrystalline environment for the cooling ion, in an easy to engineer glass. The glasses with composition 30SiO2-15Al2O3-27CdF2-22PbF2-4YF3-2YbF3 (mol%), have been prepared by the conventional melt-quenching technique. By a simple post fabrication thermal treatment, the rare-earth ions are embedded in the crystalline phase within the glass matrix. Nanocrystals with various sizes and rare-earth concentrations have been fabricated and their photoluminescence properties assessed in detail. These materials show close to unity photoluminescence quantum yield (PLQY) when pumped above the band. However, they exhibit strong up-conversion into the blue, characteristic of Tm trace impurity whose presence was confirmed. The purification of the starting materials is underway to reduce the background loss to demonstrate laser cooling. Progress in the development of these nano-glass-ceramics and their experimental characterization will be discussed.

  6. Preparation, crystal structure, spectra and energy levels of the trivalent ytterbium ion doped into rare earth stannates

    NASA Astrophysics Data System (ADS)

    Ning, Kaijie; Zhang, Qingli; Sun, Dunlu; Yin, Shaotang; Jiang, Haihe

    2011-11-01

    Yb3+-doped Rare Earth Stannates Ln2Sn2O7(Ln=Y, Gd) with space group Fd3m were synthesized by co-precipitation technique. Their structures were determined by Rietveld refinement to their X-ray diffraction, and their atom coordinates, lattice parameters and temperature factors were given. From emission, absorption and excitation spectra, the energy levels of Yb3+ in Ln2Sn2O7(Ln=Y, Gd) were assigned and the crystal field parameters were fitted to energy splitting of Yb3+-doped Ln2Sn2O7 (Ln=Y, Gd).

  7. Preparation, crystal structure, spectra and energy levels of the trivalent ytterbium ion doped into rare earth stannates

    NASA Astrophysics Data System (ADS)

    Ning, Kaijie; Zhang, Qingli; Sun, Dunlu; Yin, Shaotang; Jiang, Haihe

    2012-01-01

    Yb3+-doped Rare Earth Stannates Ln2Sn2O7(Ln=Y, Gd) with space group Fd3m were synthesized by co-precipitation technique. Their structures were determined by Rietveld refinement to their X-ray diffraction, and their atom coordinates, lattice parameters and temperature factors were given. From emission, absorption and excitation spectra, the energy levels of Yb3+ in Ln2Sn2O7(Ln=Y, Gd) were assigned and the crystal field parameters were fitted to energy splitting of Yb3+-doped Ln2Sn2O7 (Ln=Y, Gd).

  8. An Integrated Concept on Earth and Environmental Sciences Postgraduate Education

    NASA Astrophysics Data System (ADS)

    Grosfeld, Klaus; Lohmann, Gerrit; Ladstätter-Weißenmayer, Annette; Burrows, John; Sprengel, Claudia; Bijma, Jelle

    2010-05-01

    Today's graduate and postgraduate education in the field of Earth System and Environmental Science is a highly interdisciplinary and inter-institutional challenge. The integration of observations, palaeoclimate data, and climate modelling requires networks and collaborations of experts and specialists in order to better understand natural climate variations over a broad range of timescales and disciplines, and to cope with the challenges of recent climate change. The existing research infrastructure at the Alfred-Wegener-Institut Bremerhaven (AWI), University of Bremen, and Jacobs University Bremen offers a unique research environment in north-western Germany to study past, present and future changes of the climate system, with special focus on high latitudinal processes. It covers all kind of disciplines, climate science, geosciences and biosciences, and provides a consistent framework for education and qualification of a new generation of expertly trained, internationally competitive master and PhD students. On postgraduate level, the Postgraduate Programme Environmental Physics (PEP) at the University of Bremen (www.pep.uni-bremen.de) educates the participants on the complex relationship between atmosphere, hydrosphere (ocean), cryosphere (ice region) and solid earth (land). Here, the learning of experimental methods in environmental physics at the most advanced level, numerical data analysis using supercomputers, and data interpretation via sophisticated methods prepare students for a scientific career. Within cooperation with the Ocean University of China (OUC) students are participating one year in the PEP programme during their master studies since 2006, to get finally a double degree of both universities. Based on this successful cooperation a similar programme is in preparation with the Lulea University of Technology, Sweden. The Earth System Science Research School (ESSReS) (www.earth-system-science.org) at the AWI enables PhD students from a variety of

  9. The MCVD synthesis and characterization of water tolerant fiber optic waveguides based on alkaline earth-doped silicas

    NASA Astrophysics Data System (ADS)

    Farley, Kevin F.

    Optical fibers that transmit throughout the entire telecommunications spectrum (1.2--1.7 mum) are presently manufactured by the removal of hydrogen or OH from the host preform glass. Hydrogen-oxygen torches are utilized in the conventional preform manufacturing process, but result in the formation of hydroxyls in germanium-doped silica fiber. The hydroxyl species generate unacceptably high losses for long haul telecommunications systems. This thesis has explored an alternative strategy for reducing OH-related absorption in silica-based glasses. Alkaline earth modifiers have been introduced via the modified chemical vapor deposition (MCVD) process to successfully damp out and dramatically reduce the extrinsic attenuation associated with both water and hydrogen. Specifically, alkaline earth ions were introduced into alumino-silicate glasses to form MgO-Al2O3-SiO2, CaO-Al 2O3-SiO2, and SrO-Al2O3-SiO 2 compositions. The utilization of halide precursors based on the vapor delivery of rare earths was incorporated into the existing MCVD set-up to fabricate these optical preforms. Both the bulk preforms and fibers drawn from them were characterized to determine relevant optical properties, including the attenuation, index profiles and extinction coefficients arising from OH in each host. The data indicate that modification of the silica glass structure through the additions of modifying ions can significantly reduce OH related absorption. For example, the doping of alkaline earth ions decreased the extinction coefficient measured at the 1.39 mum) OH overtone, to values < 0.2 L/(mol*cm). Prompt gamma activation analysis (PGAA) measurements conducted at the National Institute of Standards and Technology (NIST) found OH concentrations in the glasses in the range from 10 to 27.5 ppm. The alkaline earth-doped fibers exhibited lower OH absorption at 1.39 mum) than germanium and aluminum-doped reference fibers. Fibers doped with either magnesium, calcium or strontium displayed up

  10. Synthesis, characterization and processing of active rare earth-doped chalcohalide glasses

    NASA Astrophysics Data System (ADS)

    Debari, Roberto Mauro

    Applications for infrared-transmitting non-oxide glass fibers span a broad range of topics. They can be used in the military, the medical field, telecommunications, and even in agriculture. Rare earth ions are used as dopants in these glasses in order to stimulate emissions in the infrared spectral region. In order to extend the host glass transmission further into the infrared, selenium atoms were substituted for sulfur in the established Ge-S-I chalcohalide glass system and the fundamental properties of these latter glasses were explored. Over 30 different compositions in the Ge-Se-I glass system were investigated as to their thermal and optical properties. The resulting optimum host with a composition of Ge15Se80I5 has a broad transmission range from 0.7 mum to 17.0 mum and a high working range over 145°C. The host glass also exhibited a Tg of 125°C, making rotational casting of a cladding tube for rod-and-tube fiberization a possibility. The base glass was doped with 1000 to 4000 ppm/wt of erbium, dysprosium, or neodymium. When doped with Er3+-ions, absorptions at 1.54 mum and 3.42 mum were observed. Nd3+-doping resulted in an absorption peak near 4.24 mum and Dy3+ ions caused absorption at 1.30 mum. Fluorescence emissions were found for neodymium at 1.396 mum with a FWHM of 74 nm, and for dysprosium at 1.145 mum with a FWHM of 75 nm, at 1.360 mum with a FWHM of 98 rim and at 1.674 mum with a FWHM of 60 nm. High optical quality tubes of the host glass could be formed using rotational casting in silica ampoules. Glass tubes, 4 to 6 cm long with a 1 cm outer diameter and a tailored inner-hole diameter ranging from 0.4 to 0.6 cm could be synthesized by this process with excellent dimensional tolerances around the circumference as well as along the length. A preform of this size provided 25 continuous meters of unclad fiber with diameters ranging from 140 to 200 mum. A UV-curable acrylate cladding was applied via an external coating cup. An x-ray analysis of the

  11. The unusually high Tc in rare-earth-doped single crystalline CaFe2As2

    NASA Astrophysics Data System (ADS)

    Wei, Fengyan; Lv, Bing; Deng, Liangzi; Meen, James K.; Xue, Yu-Yi; Chu, Ching-Wu

    2014-08-01

    In rare-earth-doped single crystalline CaFe2As2, the mysterious small volume fraction which superconducts up to 49 K, much higher than the bulk Tc ~ 30 s K, has prompted a long search for a hidden variable that could enhance the Tc by more than 30% in iron-based superconductors of the same structure. Here we report a chemical, structural and magnetic study of CaFe2As2 systematically doped with La, Ce, Pr and Nd. Coincident with the high Tc phase, we find extreme magnetic anisotropy, accompanied by an unexpected doping-independent Tc and equally unexpected superparamagnetic clusters associated with As vacancies. These observations lead us to conjecture that the tantalizing Tc enhancement may be associated with naturally occurring chemical interfaces and may thus provide a new paradigm in the search for superconductors with higher Tc.

  12. Earth From Space: "Beautiful Earth's" Integration of Media Arts, Earth Science, and Native Wisdom in Informal Learning Environments

    NASA Astrophysics Data System (ADS)

    Casasanto, V.; Hallowell, R.; Williams, K.; Rock, J.; Markus, T.

    2015-12-01

    "Beautiful Earth: Experiencing and Learning Science in an Engaging Way" was a 3-year project funded by NASA's Competitive Opportunities in Education and Public Outreach for Earth and Space Science. An outgrowth of Kenji Williams' BELLA GAIA performance, Beautiful Earth fostered a new approach to teaching by combining live music, data visualizations and Earth science with indigenous perspectives, and hands-on workshops for K-12 students at 5 science centers. Inspired by the "Overview Effect," described by many astronauts who were awestruck by seeing the Earth from space and their realization of the profound interconnectedness of Earth's life systems, Beautiful Earth leveraged the power of multimedia performance to serve as a springboard to engage K-12 students in hands-on Earth science and Native wisdom workshops. Results will be presented regarding student perceptions of Earth science, environmental issues, and indigenous ways of knowing from 3 years of evaluation data.

  13. Synthesis and characterization of rare earth doped novel optical materials and their potential applications

    NASA Astrophysics Data System (ADS)

    Pokhrel, Madhab

    There are many application of photonic materials but selection of photonic materials are always constrained by number of factors such as cost, availability of materials, thermal and chemical stability, toxicity, size and more importantly ease of synthesis and processing along with the efficient emission. For example, quantum dots are efficient emitter but they are significantly toxic, whereas dyes are also efficient emitters but they are chemically unstable. On the other hand, display and LED requires the micron size particles but bio application requires the nano-sized particles. On the other hand, laser gain media requires the ceramics glass or single crystal not the nanoparticles. So, realization of practical optical systems critically depends on suitable materials that offer specific combinations of properties. Solid-state powders such as rare-earth ions doped nano and micron size phosphors are one of the most promising candidates for several photonic applications discussed above. In this dissertation, we investigate the upconversion (UC) fluorescence characteristics of rare earth (RE) doped M2O2S (M = Y, Gd, La) oxysulphide phosphors, for near-infrared to visible UC. Both nano and micron size phosphors were investigated depending on their applications of interest. This oxysulphide phosphor possesses several excellent properties such as chemical stability, low toxicity and can be easily mass produced at low cost. Mainly, Yb3+, Er3+, and Ho3+ were doped in the host lattice, resulting in bright red, green, blue and NIR emissions under 980 nm and 1550 nm excitation at various excitation power densities. Maximum UC quantum yields (QY) up to 6.2 %, 5.8%, and 4.6% were respectively achieved in Yb3+/Er3+ :La2O2S, Y2O2S, and Gd2O 2S. Comparisons have been made with respect to reported most efficient upconverting phosphors beta-NaYF4:20 % Yb/ 2% Er. We believe that present phosphors are the most efficient and lower excitation threshold upconverting phosphors at 980 and

  14. Rare-earth doped colour tuneable up-conversion ZBLAN phosphor for enhancing photocatalysis

    NASA Astrophysics Data System (ADS)

    Méndez-Ramos, J.; Acosta-Mora, P.; Ruiz-Morales, J. C.; Sierra, M.; Redondas, A.; Ruggiero, E.; Salassa, L.; Borges, M. E.; Esparza, P.

    2015-03-01

    Rare-earth doped ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) fluoride glasses have been successfully synthesized showing outstanding UV-VIS up-conversion luminescence of Er3+ and Tm3+, sensitized by Yb3+ ions, under near-infrared excitation at 980 nm. The ratio between blue, green and red up-conversion emission bands can be adjusted by varying the pump power density of the incident infrared radiation, resulting in a controlled tuneability of the overall emitting colour from greenish to yellowish. Additionally, the observed high energy UV intense up-conversion emissions are suitable to enhance photocatalytic activity of main water-splitting semiconductor electrodes (such as TiO2) used in sustainable production of hydrogen. Photocatalysis and photolysis degradation of methylene blue in water under sun-like irradiation using benchmark photocatalyst (TiO2 Degussa P25) have been boosted by 20% and by a factor of 2.5 respectively, due to the enhancement of UV radiation that reaches the TiO2 particles by the addition of ZBLAN powder into a slurry-type photo-reactor. Hence, up-conversion ZBLAN phosphors contribute to demonstrate the possibility of transforming the incoming infrared radiation into the UV region needed to bridge the gap of photocatalytic semiconductors.

  15. Structure-property-composition relationships in doped zinc oxides: enhanced photocatalytic activity with rare earth dopants.

    PubMed

    Goodall, Josephine B M; Illsley, Derek; Lines, Robert; Makwana, Neel M; Darr, Jawwad A

    2015-02-01

    In this paper, we demonstrate the use of continuous hydrothermal flow synthesis (CHFS) technology to rapidly produce a library of 56 crystalline (doped) zinc oxide nanopowders and two undoped samples, each with different particle properties. Each sample was produced in series from the mixing of an aqueous stream of basic zinc nitrate (and dopant ion or modifier) solution with a flow of superheated water (at 450 °C and 24.1 MPa), whereupon a crystalline nanoparticle slurry was rapidly formed. Each composition was collected in series, cleaned, freeze-dried, and then characterized using analytical methods, including powder X-ray diffraction, transmission electron microscopy, Brunauer-Emmett-Teller surface area measurement, X-ray photoelectron spectroscopy, and UV-vis spectrophotometry. Photocatalytic activity of the samples toward the decolorization of methylene blue dye was assessed, and the results revealed that transition metal dopants tended to reduce the photoactivity while rare earth ions, in general, increased the photocatalytic activity. In general, low dopant concentrations were more beneficial to having greater photodecolorization in all cases.

  16. Rare-earth-doped nanophosphors for multicolor cathodoluminescence nanobioimaging using scanning transmission electron microscopy.

    PubMed

    Furukawa, Taichi; Fukushima, Shoichiro; Niioka, Hirohiko; Yamamoto, Naoki; Miyake, Jun; Araki, Tsutomu; Hashimoto, Mamoru

    2015-05-01

    We describe rare-earth-doped nanophosphors (RE-NPs) for biological imaging using cathodoluminescence(CL) microscopy based on scanning transmission electron microscopy (STEM). We report the first demonstration of multicolor CL nanobioimaging using STEM with nanophosphors. The CL spectra of the synthesized nanophosphors (Y2O3∶Eu, Y2O3∶Tb) were sufficiently narrow to be distinguished. From CL images of RE-NPs on an elastic carbon-coated copper grid, the spatial resolution was beyond the diffraction limit of light.Y2O3∶Tb and Y2O3∶Eu RE-NPs showed a remarkable resistance against electron beam exposure even at high acceleration voltage (80 kV) and retained a CL intensity of more than 97% compared with the initial intensity for 1 min. In biological CL imaging with STEM, heavy-metal-stained cell sections containing the RE-NPs were prepared,and both the CL images of RE-NPs and cellular structures, such as mitochondria, were clearly observed from STEM images with high contrast. The cellular CL imaging using RE-NPs also had high spatial resolution even though heavy-metal-stained cells are normally regarded as highly scattering media. Moreover, since theRE-NPs exhibit photoluminescence (PL) excited by UV light, they are useful for multimodal correlative imaging using CL and PL.

  17. Visible WGM emissions from rare earth ion doped ZnO microspheres

    NASA Astrophysics Data System (ADS)

    K, Fabitha; Rao, M. S. Ramachandra

    ZnO is known to be an ideal candidate for short wavelength range opto-electronic device applications due to its wide and direct bandgap (3.37 eV) and high excitonic binding energy (60 meV). Apart from the UV emission at ~380 nm (free exciton emission) ZnO also possesses a broad emission band centered at ~530 nm which is expected to be originated from the oxygen vacancy (Vo) defects. In rare earth (RE) ion doped ZnO, emissions originate from the 4f levels of RE ions will be obtained in addition to the characteristic emissions of ZnO. Small micro/nanostructures made of ZnO with high crystalline quality show unique characteristics in light emission, especially in lasing applications. A micro/ nanostructured ZnO crystal generally has a wurtzite structure with a natural hexagonal cross section, which serves as a WGM lasing micro cavity owing to its high reflective index (~2). However, there exists a potential optical loss at corners of hexagons; therefore, an isotropic structure like spheres may be a better candidate to achieve efficient light confinement. In our work, highly smooth micro spheres with different diameters were grown. Raman spectroscopy measurements confirm the hexagonal wurtzite structure of ZnO, SEM and AFM studies shows the smooth surfaced spheres. WGM lasing characteristics of ZnO spheres have been investigated using optical pumping with 488 nm laser in a micro-PL system. Details of the results will be presented.

  18. Synthesis and structure of some nano-sized rare-earth metal ions doped potassium hexacyanoferrates

    NASA Astrophysics Data System (ADS)

    Narayan, Himanshu; Alemu, Hailemichael; Nketsa, Pusetso F.; Manatha, Toka J.; Madhavi Thakurdesai, And

    2015-05-01

    Rare-earth ions doped potassium hexacyanoferrates (KR-HCF); with the general formula KRFe(CN)6 · 3H2 O [with, R≡Y, Gd and Yb] nanoparticles were synthesized through precipitation. Characterization was done through particle-size analyzer, scanning electron microscopy (SEM), Fourier Transform infra-red (FTIR) and Raman spectroscopy, and powder X-ray diffraction (XRD). The XRD data was analyzed on FullProf Software Suite program and the unit-cell structure and lattice parameters of KR-HCF samples were determined from scratch and refined further. All the three KR-HCF nanoparticles seem to crystallize in the orthorhombic primitive PMMM space-group. Reasonably good agreement was found with the previously reported lattice constants of KGd-HCF and KYb-HCF orthorhombic single-crystals, except that they assume different space-groups. The observed dissimilarity of space-groups may be attributed to the different time scales involved in the synthesis process. Moreover, the crystal structure of KYFe(CN)6 · 3H2 O nanoparticles is being reported for the very first time.

  19. Processing of Transparent Rare Earth Doped Zirconia for High Temperature Light Emission Applications

    NASA Astrophysics Data System (ADS)

    Hardin, Corey Lee

    The high fracture toughness of stabilized zirconia makes it one of the most widely applicable high temperature structural materials. However, it is not typicality considered for optical applications since the microstructure achieved by traditional processing makes it opaque. The aim of this dissertation is to develop processing methods for the introducing new functionalities of light transparency and light emission (photoluminescence) and to understand the nanostructure-property relationships that make these functionalities possible. A processing study of rare-earth (RE) doped Zirconium Oxide (ZrO2, zirconia) via Current Activated Pressure Assisted Densification (CAPAD) is presented. The role of processing temperature and dopant concentration on the crystal structure, microstructure and properties of the RE: ZrO2 is studied. Microstructural shows sub-100 nm grain size and homogeneous dopant distribution. X-ray diffraction and Raman analysis show that with increased dopant concentration the material changes from monoclinic to tetragonal. Structural analysis shows the material shows high hardness and toughness values 30% greater than similarly processed yttria-stabilized zirconia. Despite birefringence in the tetragonal phase, optical characterization is presented showing the samples are both highly transparent and photo-luminescent. Special attention is paid to analyzing structural and photoluminescence development during densification, as well as the role of oxygen vacancies on the optical properties of the densified material. This material is shown to be a promising candidate for a number of applications including luminescence thermometry and high temperature light emission.

  20. The Characterization of Eu2+-Doped Mixed Alkaline-Earth Iodide Scintillator Crystals

    SciTech Connect

    Neal, John S; Boatner, Lynn A; Ramey, Joanne Oxendine; Wisniewski, D.; Kolopus, James A; Cherepy, Nerine; Payne, Stephen A.

    2011-01-01

    The high-performance inorganic scintillator, SrI2:Eu2+, when activated with divalent europium in the concentration range of 3 to 6%, has shown great promise for use in applications that require high-energy-resolution gamma-ray detection. We have recently grown and tested crystals in which other alkaline-earth ions have been partially substituted for Sr ions. Specifically, europium-doped single crystals have been grown in which up to 30 at % of the strontium ions have been substituted for either by barium, magnesium, or calcium ions. In the case of the strontium iodide scintillator host, a material that is characterized by an orthorhombic crystal structure, there are three other column IIA elements that are obvious choices for investigations whose purpose is to realize potential improvements in the performance of SrI2:Eu2+-based scintillators via the replacement of strontium ions with either Mg2+, Ca2+, or Ba2+. Light yields of up to 81,400 photons/MeV with an associated energy resolution of 3.7% (fwhm for 662 keV gamma-rays) have been observed in the case of a partial substitution of Ba2+ for Sr2+. The measured decay times ranged from 1.1 to 2.0 s, while the peak emission wavelengths ranged from 432 to 438 nm.

  1. Direct quantification of rare earth doped titania nanoparticles in individual human cells.

    PubMed

    Jeynes, J C G; Jeynes, C; Palitsin, V; Townley, H E

    2016-07-15

    There are many possible biomedical applications for titania nanoparticles (NPs) doped with rare earth elements (REEs), from dose enhancement and diagnostic imaging in radiotherapy, to biosensing. However, there are concerns that the NPs could disintegrate in the body thus releasing toxic REE ions to undesired locations. As a first step, we investigate how accurately the Ti/REE ratio from the NPs can be measured inside human cells. A quantitative analysis of whole, unsectioned, individual human cells was performed using proton microprobe elemental microscopy. This method is unique in being able to quantitatively analyse all the elements in an unsectioned individual cell with micron resolution, while also scanning large fields of view. We compared the Ti/REE signal inside cells to NPs that were outside the cells, non-specifically absorbed onto the polypropylene substrate. We show that the REE signal in individual cells co-localises with the titanium signal, indicating that the NPs have remained intact. Within the uncertainty of the measurement, there is no difference between the Ti/REE ratio inside and outside the cells. Interestingly, we also show that there is considerable variation in the uptake of the NPs from cell-to-cell, by a factor of more than 10. We conclude that the NPs enter the cells and remain intact. The large heterogeneity in NP concentrations from cell-to-cell should be considered if they are to be used therapeutically. PMID:27255758

  2. Direct quantification of rare earth doped titania nanoparticles in individual human cells

    NASA Astrophysics Data System (ADS)

    Jeynes, J. C. G.; Jeynes, C.; Palitsin, V.; Townley, H. E.

    2016-07-01

    There are many possible biomedical applications for titania nanoparticles (NPs) doped with rare earth elements (REEs), from dose enhancement and diagnostic imaging in radiotherapy, to biosensing. However, there are concerns that the NPs could disintegrate in the body thus releasing toxic REE ions to undesired locations. As a first step, we investigate how accurately the Ti/REE ratio from the NPs can be measured inside human cells. A quantitative analysis of whole, unsectioned, individual human cells was performed using proton microprobe elemental microscopy. This method is unique in being able to quantitatively analyse all the elements in an unsectioned individual cell with micron resolution, while also scanning large fields of view. We compared the Ti/REE signal inside cells to NPs that were outside the cells, non-specifically absorbed onto the polypropylene substrate. We show that the REE signal in individual cells co-localises with the titanium signal, indicating that the NPs have remained intact. Within the uncertainty of the measurement, there is no difference between the Ti/REE ratio inside and outside the cells. Interestingly, we also show that there is considerable variation in the uptake of the NPs from cell-to-cell, by a factor of more than 10. We conclude that the NPs enter the cells and remain intact. The large heterogeneity in NP concentrations from cell-to-cell should be considered if they are to be used therapeutically.

  3. Building thematic and integrated services for solid Earth sciences: the EPOS integrated approach

    NASA Astrophysics Data System (ADS)

    Cocco, Massimo; Consortium, Epos

    2016-04-01

    EPOS has been designed with the vision of creating a pan-European infrastructure for solid Earth science to support a safe and sustainable society. In accordance with this scientific vision, the EPOS mission is to integrate the diverse and advanced European Research Infrastructures for solid Earth science relying on new e-science opportunities to monitor and unravel the dynamic and complex Earth System. EPOS will enable innovative multidisciplinary research for a better understanding of the Earth's physical and chemical processes that control earthquakes, volcanic eruptions, ground instability and tsunami as well as the processes driving tectonics and Earth's surface dynamics. To accomplish its mission, EPOS is engaging different stakeholders, not limited to scientists, to allow the Earth sciences to open new horizons in our understanding of the planet. EPOS also aims at contributing to prepare society for geo-hazards and to responsibly manage the exploitation of geo-resources. Through integration of data, models and facilities, EPOS will allow the Earth science community to make a step change in developing new concepts and tools for key answers to scientific and socio-economic questions concerning geo-hazards and geo-resources as well as Earth sciences applications to the environment and human welfare. A long-term integration plan is necessary to accomplish the EPOS mission. EPOS is presently in its implementation phase further extending its pan-European dimension. The EPOS Implementation Phase builds on the achievements of the successful EPOS Preparatory Phase project and consists of two key activities: the legal establishment of the EPOS-ERIC and the EPOS IP project. The EPOS implementation phase will last from 2015 to 2019. Key objectives of the project are: implementing Thematic Core Services (TCS), the domain-specific service hubs for coordinating and harmonizing national resources/plans with the European dimension of EPOS; building the Integrated Core

  4. An integrated view of data quality in Earth observation.

    PubMed

    Yang, X; Blower, J D; Bastin, L; Lush, V; Zabala, A; Masó, J; Cornford, D; Díaz, P; Lumsden, J

    2013-01-28

    Data quality is a difficult notion to define precisely, and different communities have different views and understandings of the subject. This causes confusion, a lack of harmonization of data across communities and omission of vital quality information. For some existing data infrastructures, data quality standards cannot address the problem adequately and cannot fulfil all user needs or cover all concepts of data quality. In this study, we discuss some philosophical issues on data quality. We identify actual user needs on data quality, review existing standards and specifications on data quality, and propose an integrated model for data quality in the field of Earth observation (EO). We also propose a practical mechanism for applying the integrated quality information model to a large number of datasets through metadata inheritance. While our data quality management approach is in the domain of EO, we believe that the ideas and methodologies for data quality management can be applied to wider domains and disciplines to facilitate quality-enabled scientific research.

  5. An integrated view of data quality in Earth observation

    PubMed Central

    Yang, X.; Blower, J. D.; Bastin, L.; Lush, V.; Zabala, A.; Masó, J.; Cornford, D.; Díaz, P.; Lumsden, J.

    2013-01-01

    Data quality is a difficult notion to define precisely, and different communities have different views and understandings of the subject. This causes confusion, a lack of harmonization of data across communities and omission of vital quality information. For some existing data infrastructures, data quality standards cannot address the problem adequately and cannot fulfil all user needs or cover all concepts of data quality. In this study, we discuss some philosophical issues on data quality. We identify actual user needs on data quality, review existing standards and specifications on data quality, and propose an integrated model for data quality in the field of Earth observation (EO). We also propose a practical mechanism for applying the integrated quality information model to a large number of datasets through metadata inheritance. While our data quality management approach is in the domain of EO, we believe that the ideas and methodologies for data quality management can be applied to wider domains and disciplines to facilitate quality-enabled scientific research. PMID:23230156

  6. Mars for Earthlings: A Higher Educational Terrestrial Analog Approach for Teaching Integrated Earth and Planetary Science

    NASA Astrophysics Data System (ADS)

    Chan, M. A.; Robinson, J. K.

    2012-03-01

    "Mars for Earthlings" teaching modules use Earth analogs to explore Mars at an introductory college level. This integrated approach increases science literacy and attracts students to STEM disciplines.

  7. Rare-Earth Doped Wide Bandgap Oxide Semiconductor Materials and Devices

    NASA Astrophysics Data System (ADS)

    Wellenius, Ian Patrick

    Amorphous oxide semiconductors composed of indium gallium zinc oxide are transparent to visible light and have higher electron mobilities than conventional amorphous semiconductors, such as amorphous silicon. The advantages of higher switching speed, lack of dangling bonds leading to good electronic stability and visible spectrum transparency of amorphous oxide semiconductor devices are expected to lead to numerous applications, including transparent displays and flexible electronics. In this thesis the integration of transparent thin film transistors with transparent electroluminescent pixels was investigated. Compared with display technologies employing organic semiconductors that degrade with exposure to moisture and ultraviolet light, the all-oxide structure of this device is expected to be environmentally robust. This is believed to be the first demonstration of an integrated active matrix pixel using amorphous oxide semiconductor materials as both the light emitter and addressing circuit elements. The transparent active matrix pixel was designed, fabricated and characterized, that integrated amorphous indium gallium zinc oxide (IGZO) thin film transistors (TFTs) with a europium-doped IGZO thin film electroluminescent (TFEL) device. The integrated circuits were fabricated using room temperature pulsed laser deposition (PLD) of IGZO and ITO thin films onto substrates of Corning 7059 glass, sputter coated with an ITO back contact and subsequent atomic layer deposited ATO high-k dielectric. A second ITO layer is deposited by PLD as a contact and interconnect layer. All deposition steps were carried out at room temperature. In addition to the integration task, an important part of this thesis concerns the investigation of europium as a dopant in different oxide hosts including gallium oxide, gadolinium oxide, and amorphous IGZO. Amorphous IGZO was chosen for the integration task since it could be deposited at room temperature, however it was found that the

  8. Visualization of melanoma tumor with lectin-conjugated rare-earth doped fluoride nanocrystals

    PubMed Central

    Dumych, Tetiana; Lutsyk, Maxym; Banski, Mateusz; Yashchenko, Antonina; Sojka, Bartlomiej; Horbay, Rostyslav; Lutsyk, Alexander; Stoika, Rostyslav; Misiewicz, Jan; Podhorodecki, Artur; Bilyy, Rostyslav

    2014-01-01

    Aim To develop specific fluorescent markers for melanoma tumor visualization, which would provide high selectivity and reversible binding pattern, by the use of carbohydrate-recognizing proteins, lectins, combined with the physical ability for imaging deep in the living tissues by utilizing red and near infrared fluorescent properties of specific rare-earth doped nanocrystals (NC). Methods B10F16 melanoma cells were inoculated to C57BL/6 mice for inducing experimental melanoma tumor. Tumors were removed and analyzed by lectin-histochemistry using LABA, PFA, PNA, HPA, SNA, GNA, and NPL lectins and stained with hematoxylin and eosin. NPL lectin was conjugated to fluorescent NaGdF4:Eu3+-COOH nanoparticles (5 nm) via zero length cross-linking reaction, and the conjugates were purified from unbound substances and then used for further visualization of histological samples. Fluorescent microscopy was used to visualize NPL-NaGdF4:Eu3+ with the fluorescent emission at 600-720 nm range. Results NPL lectin selectively recognized regions of undifferentiated melanoblasts surrounding neoangiogenic foci inside melanoma tumor, PNA lectin recognized differentiated melanoblasts, and LCA and WGA were bound to tumor stroma regions. NPL-NaGdF4:Eu3+ conjugated NC were efficiently detecting newly formed regions of melanoma tumor, confirmed by fluorescent microscopy in visible and near infrared mode. These conjugates possessed high photostability and were compatible with convenient xylene-based mounting systems and preserved intensive fluorescent signal at samples storage for at least 6 months. Conclusion NPL lectin-NaGdF4:Eu3+ conjugated NC permitted distinct identification of contours of the melanoma tissue on histological sections using red excitation at 590-610 nm and near infrared emission of 700-720 nm. These data are of potential practical significance for development of glycans-conjugated nanoparticles to be used for in vivo visualization of melanoma tumor. PMID:24891277

  9. Polarization dependence of two-photon transition intensities in rare-earth doped crystals

    SciTech Connect

    Le Nguyen, An-Dien

    1996-05-01

    A polarization dependence technique has been developed as a tool to investigate phonon scattering (PS), electronic Raman scattering (ERS), and two-photon absorption (TPA) transition intensities in vanadate and phosphate crystals. A general theory for the polarization dependence (PD) of two-photon transition intensities has been given. Expressions for the polarization dependent behavior of two-photon transition intensities have been tabulated for the 32 crystallographic point groups. When the wavefunctions for the initial and final states of a rare-earth doped in crystals are known, explicit PD expressions with no unknown parameters can be obtained. A spectroscopic method for measuring and interpreting phonon and ERS intensities has been developed to study PrVO{sub 4}, NdVO{sub 4}, ErVO{sub 4}, and TmVO{sub 4} crystals. Relative phonon intensities with the polarization of the incident and scattered light arbitrarily varied were accurately predicted and subsequently used for alignment and calibration in ERS measurements in these systems for the first time. Since ERS and PS intensities generally follow different polarization curves as a function of polar angles, the two can be uniquely identified by comparing their respective polarization behavior. The most crucial application of the technique in ERS spectroscopy is the establishment of a stringent test for the Axe theory. For the first time, the F{sub 1}/F{sub 2} ratio extracted from the experimental fits of the ERS intensities were compared with those predicted by theories which include both the second- and third-order contributions. Relatively good agreement between the fitted values of F{sub 1}/F{sub 2} and the predicted values using the second-order theory has been found.

  10. Evidence for interface superconductivity in rare-earth doped CaFe2As2 single crystals

    NASA Astrophysics Data System (ADS)

    Lv, Bing; Deng, L. Z.; Wei, F. Y.; Xue, Y. Y.; Chu, C. W.

    2014-03-01

    To unravel to the mysterious non-bulk superconductivity up to 49K observed in rare-earth (R =La, Ce, Pr and Nd) doped CaFe2As2 single-crystals whose Tc is higher than that of any known compounds consisting of one or more of its constituent elements of R, Ca, Fe, and As at ambient or under pressures, systematic magnetic, compositional and structural have carried out on different rare-earth-doped (Ca1-xRx) Fe2As2 samples. We have detected extremely large magnetic anisotropy, doping-level independent Tc, unexpected superparamagnetic clusters associated with As vacancies and their close correlation with the superconducting volume fraction, the existence of mesoscopic-2D structures and Josephson-junction arrays in this system. These observations lead us to conjecture that the Tc enhancement may be associated with naturally occurring chemical interfaces and thus provided evidence for the possible interface-enhanced Tc in naturally-grown single crystals of Fe-based superconductors.

  11. Rare earth doped SnO2 nanoscaled powders and coatings: enhanced photoluminescence in water and waveguiding properties.

    PubMed

    Gonçalves, R R; Messaddeq, Y; Aegerter, M A; Ribeiro, S J L

    2011-03-01

    Luminescent Eu3+ and Er3+ doped SnO2 powders have been prepared by Sn4+ hydrolysis followed by a controlled growth reaction using a particle's surface modifier in order to avoid particles aggregation. The powders so obtained doped with up to 2 mol% rare earth ions are fully redispersable in water at pH > 8 and present the cassiterite structure. Particles size range from 3 to 10 nm as determined by Photon Correlation Spectroscopy. Rare earth ions were found to be essentially incorporated into the cassiterite structure, substituting for Sn4+, for doping concentration smaller than 0.05 mol%. For higher concentration they are also located at the particles surface. The presence of Eu3+ ions at the surface of the particles hinder their growth and has therefore allowed the preparation of new materials consisting of water redispersable powders coated with Eu(3+)-beta diketonate complexes. Enhanced UV excited photoluminescence was observed in water. SnO2 single layers with thickness up to 200 nm and multilayer coatings were spin coated on borosilicate glass substrates from the colloidal suspensions. Waveguiding properties were evaluated by the prism coupling technique. For a 0.3 microm planar waveguide single propagating mode was observed with attenuation coefficient of 3.5 dB/cm at 632.8 nm. PMID:21449404

  12. Use of thulium-sensitized rare earth-doped low phonon energy crystalline hosts for IR sources.

    PubMed

    Ganem, Joseph; Bowman, Steven R

    2013-11-01

    Crystalline hosts with low phonon energies enable novel energy transfer processes when doped with rare earth ions. Two applications of energy transfer for rare earth ions in thulium-sensitized low phonon energy crystals that result in infrared luminescence are discussed. One application is an endothermic, phonon-assisted cross-relaxation process in thulium-doped yttrium chloride that converts lattice phonons to infrared emission, which raises the possibility of a fundamentally new method for achieving solid-state optical cooling. The other application is an optically pumped mid-IR phosphor using thulium-praseodymium-doped potassium lead chloride that converts 805-nm diode light to broadband emission from 4,000 to 5,500 nm. These two applications in chloride crystals are discussed in terms of critical radii calculated from Forster-Dexter energy transfer theory. It is found that the critical radii for electric dipole-dipole interactions in low phonon energy chloride crystals are comparable to those in conventional oxide and fluoride crystals. It is the reduction in multi-phonon relaxation rates in chloride crystals that enable these additional energy transfer processes and infrared luminescence.

  13. Use of thulium-sensitized rare earth-doped low phonon energy crystalline hosts for IR sources

    PubMed Central

    2013-01-01

    Crystalline hosts with low phonon energies enable novel energy transfer processes when doped with rare earth ions. Two applications of energy transfer for rare earth ions in thulium-sensitized low phonon energy crystals that result in infrared luminescence are discussed. One application is an endothermic, phonon-assisted cross-relaxation process in thulium-doped yttrium chloride that converts lattice phonons to infrared emission, which raises the possibility of a fundamentally new method for achieving solid-state optical cooling. The other application is an optically pumped mid-IR phosphor using thulium-praseodymium-doped potassium lead chloride that converts 805-nm diode light to broadband emission from 4,000 to 5,500 nm. These two applications in chloride crystals are discussed in terms of critical radii calculated from Forster-Dexter energy transfer theory. It is found that the critical radii for electric dipole-dipole interactions in low phonon energy chloride crystals are comparable to those in conventional oxide and fluoride crystals. It is the reduction in multi-phonon relaxation rates in chloride crystals that enable these additional energy transfer processes and infrared luminescence. PMID:24180684

  14. Use of thulium-sensitized rare earth-doped low phonon energy crystalline hosts for IR sources.

    PubMed

    Ganem, Joseph; Bowman, Steven R

    2013-01-01

    Crystalline hosts with low phonon energies enable novel energy transfer processes when doped with rare earth ions. Two applications of energy transfer for rare earth ions in thulium-sensitized low phonon energy crystals that result in infrared luminescence are discussed. One application is an endothermic, phonon-assisted cross-relaxation process in thulium-doped yttrium chloride that converts lattice phonons to infrared emission, which raises the possibility of a fundamentally new method for achieving solid-state optical cooling. The other application is an optically pumped mid-IR phosphor using thulium-praseodymium-doped potassium lead chloride that converts 805-nm diode light to broadband emission from 4,000 to 5,500 nm. These two applications in chloride crystals are discussed in terms of critical radii calculated from Forster-Dexter energy transfer theory. It is found that the critical radii for electric dipole-dipole interactions in low phonon energy chloride crystals are comparable to those in conventional oxide and fluoride crystals. It is the reduction in multi-phonon relaxation rates in chloride crystals that enable these additional energy transfer processes and infrared luminescence. PMID:24180684

  15. Use of thulium-sensitized rare earth-doped low phonon energy crystalline hosts for IR sources

    NASA Astrophysics Data System (ADS)

    Ganem, Joseph; Bowman, Steven R.

    2013-11-01

    Crystalline hosts with low phonon energies enable novel energy transfer processes when doped with rare earth ions. Two applications of energy transfer for rare earth ions in thulium-sensitized low phonon energy crystals that result in infrared luminescence are discussed. One application is an endothermic, phonon-assisted cross-relaxation process in thulium-doped yttrium chloride that converts lattice phonons to infrared emission, which raises the possibility of a fundamentally new method for achieving solid-state optical cooling. The other application is an optically pumped mid-IR phosphor using thulium-praseodymium-doped potassium lead chloride that converts 805-nm diode light to broadband emission from 4,000 to 5,500 nm. These two applications in chloride crystals are discussed in terms of critical radii calculated from Forster-Dexter energy transfer theory. It is found that the critical radii for electric dipole-dipole interactions in low phonon energy chloride crystals are comparable to those in conventional oxide and fluoride crystals. It is the reduction in multi-phonon relaxation rates in chloride crystals that enable these additional energy transfer processes and infrared luminescence.

  16. Microstructure and properties of in-flight rare-earth doped thermal barrier coatings prepared by suspension plasma spray

    NASA Astrophysics Data System (ADS)

    Gong, Stephanie

    Thermal barrier coatings with lower thermal conductivity improve the efficiency of gas turbine engines by allowing higher operating temperatures. Recent studies were shown that coatings containing a pair of rare-earth oxides with equal molar ratio have lower thermal conductivity and improved sintering resistance compared to the undoped 4-4.5 mol.% yttria-stabilized zirconia (YSZ). In the present work, rare-earth doped coatings were fabricated via suspension plasma spray by spraying YSZ powder-ethanol suspensions that contained dissolved rare-earth nitrates. The compositions of the coatings determined by inductively coupled plasma mass spectroscopy verified that 68 +/- 8% of the rare-earth nitrates added into the suspension was incorporated into the coatings. Two coatings containing different concentrations of the same dopant pair (Nd2O3/Yb2O3), and three coatings having similar concentrations of different dopant pairs (Nd 2O3/Yb2O3, Nd2O3/Gd 2O3, and Gd2O3/Yb2O 3) were produced and compared. The effect of dopant concentration and dopant pair type on the microstructure and properties of the coatings in the as-sprayed and heat treated conditions were investigated using XRD, SEM, TEM, STEM-EDX, and the laser flash method. The cross-sectional morphology of all coatings displayed columnar structure. The porosity content of the coating was found to increase with increasing dopant concentration, but did not significantly change with dopant pairs. Similarly, increasing the Nd2O3/Yb2O 3 concentration lowered the thermal conductivity of the as-sprayed coatings. Although the effect of changing dopant pair type is not as significant as increasing the dopant concentration, the coating that contained Gd2O 3/Yb2O3 exhibited the lowest conductivity compared to coatings that had other dopant pairs. Thermal conductivity measurement performed on the heat treated coatings indicated a larger conductivity increase for the rare-earth doped coatings. A detailed study on the

  17. EarthCube Integration and Test Environment (ECITE) : An environment to verify, validate, integrate and demonstrate EarthCube technology components

    NASA Astrophysics Data System (ADS)

    Fils, D.; Law, E.; Keiser, K.; Middleton, D.; Pearlman, J.; Stults, M.; MacDermaid, C.; Yang, C. P.

    2015-12-01

    NSF EarthCube is building a community-driven cyberinfrastructure that supports standards for interoperability, infuses advanced technologies to improve and facilitate interdisciplinary research, and helps educate scientists in the emerging practices of digital scholarship, data and software stewardship, and open science. A Testbed Working Group (TWG) was formed by the EarthCube's Technology and Architecture Committee, and is working with the EarthCube and user communities to define and design a testbed that will facilitate the integration of separately funded EarthCube components and promote collaborative planning, testing and integration of technologies. Specifically, the testbed seeks to: Serve as a common ground for prototyping, testing,integration and preservation of EarthCube components and products; Facilitate verification and validation of technologies, use cases, architecture design, components, scalability, interface specifications and standards; Provide a platform for demonstration and showcasing of EarthCube technologies for science users, technologists and the broader geosciences community. This talk gives a brief overview of the role, activities and accomplished achieved by the TWG, as well as the requirements and design developed to drive the implementation of a sustainable EarthCube testbed.

  18. INTEGRATED EARTH OBSERVATIONS: APPLICATION TO AIR QUALITY AND HUMAN HEALTH

    EPA Science Inventory

    In February 2005, ministers from 60 countries and the European Commission met in Brussels, Belgium to endorse the 10-year plan for a Global Earth Observation System of Systems(GEOSS) prepared by the Group on Earth Observations (GEO), a partnership of nations and international org...

  19. Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO{sub 2} fiber

    SciTech Connect

    Katsumata, Toru Morita, Kentaro; Komuro, Shuji; Aizawa, Hiroaki

    2014-08-15

    Visible light thermal radiation from SiO{sub 2} glass doped with Y, La, Ce, Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu were studied for the fiber-optic thermometer application based on the temperature dependence of thermal radiation. Thermal radiations according to Planck's law of radiation are observed from the SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu at the temperature above 1100 K. Thermal radiations due to f-f transitions of rare-earth ions are observed from the SiO{sub 2} fibers doped with Nd, Dy, Ho, Er, Tm, and Yb at the temperature above 900 K. Peak intensities of thermal radiations from rare-earth doped SiO{sub 2} fibers increase sensitively with temperature. Thermal activation energies of thermal radiations by f-f transitions seen in Nd, Dy, Ho, Er, Tm, and Yb doped SiO{sub 2} fibers are smaller than those from SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu. Thermal radiation due to highly efficient f-f transitions in Nd, Dy, Ho, Er, Tm, and Yb ions emits more easily than usual thermal radiation process. Thermal radiations from rare-earth doped SiO{sub 2} are potentially applicable for the fiber-optic thermometry above 900 K.

  20. Reduction of magnetic damping constant of FeCo films by rare-earth Gd doping

    SciTech Connect

    Guo, Xiaobin; Xi, Li Li, Yue; Han, Xuemeng; Li, Dong; Wang, Zhen; Zuo, Yalu

    2014-08-18

    Magnetic damping constant (α) is one of the key parameters to determine the critical current density of spin-transfer-torque devices and the switching time of magnetization for ultra-high-frequency devices. In this work, Gd doped FeCo films were fabricated to investigate α based on the ferromagnetic resonance technique. Gd doping not only can efficiently decrease the magnetic inhomogeneity and the extrinsic part of α but also the Landé g-factor and intrinsic part of α. The obtained α was roughly proportional to (g-2){sup 2} and the magnetic anisotropic constant, indicating that the decreased spin-orbit interaction decreases α by Gd doping.

  1. Flame synthesis and characterization of rare-earth (Er3+, Ho3+, and Tm3+) doped upconversion nanophosphors

    NASA Astrophysics Data System (ADS)

    Qin, Xiao; Yokomori, Takeshi; Ju, Yiguang

    2007-02-01

    Rare-earth doped yttria upconversion nanophosphors were synthesized using a single-step gas-phase flame synthesis method. The phosphors were characterized by x-ray diffractometry, transmission electron microscopy, and fluorescence spectroscopy. The dependence of multiphoton emissions on excitation power was examined. The results show that particle size, morphology, and photoluminescence intensity are strongly affected by flame temperature. The as-prepared nanophosphors are mostly single crystallites with an average size less than 30nm. Under laser diode excitation, bright blue, green, and red emissions are visible from these phosphors which show potential applications in biological imaging and photodynamic therapy.

  2. Chalcogenide glasses for infrared applications: New synthesis routes and rare earth doping

    NASA Astrophysics Data System (ADS)

    Hubert, Mathieu

    shift the optical band gap toward higher wavelengths. A systematic ceramization study emphasizes the difficulty of controlling the crystallization for glasses in the systems GeSe2-Ga2Se3-In2Se 3 and GeSe2-Ga2Se3-PbSe. No crystallization of the In2Se3 and PbSe crystalline phase was obtained. Finally, the possibility of producing rare-earth doped 80GeSe2 -20Ga2Se3 glass-ceramics transparent in the infrared region up to 16 microm is demonstrated. Enhanced photoluminescence intensity and reduced radiative lifetimes are observed with increased crystallinity in these materials.

  3. New Mid-IR Lasers Based on Rare-Earth-Doped Sulfide and Chloride Materials

    SciTech Connect

    Nostrand, M

    2000-09-01

    Applications in remote-sensing and military countermeasures have driven a need for compact, solid-state mid-IR lasers. Due to multi-phonon quenching, non-traditional hosts are needed to extend current solid-state, room-temperature lasing capabilities beyond {approx} 4 {micro}m. Traditional oxide and fluoride hosts have effective phonon energies in the neighborhood of 1000 cm{sup -1} and 500 cm{sup -1}, respectively. These phonons can effectively quench radiation above 2 and 4 {micro}m, respectively. Materials with lower effective phonon energies such as sulfides and chlorides are the logical candidates for mid-IR (4-10 {micro}m) operation. In this report, laser action is demonstrated in two such hosts, CaGa{sub 2}S{sub 4} and KPb{sub 2}Cl{sub 5}. The CaGa{sub 2}S{sub 4}:Dy{sup 3+} laser operating at 4.3 {micro}m represents the first sulfide laser operating beyond 2 {micro}m. The KPb{sub 2}Cl{sub 5}:Dy{sup 3+} laser operating at 2.4 {micro}m represents the first operation of a chloride-host laser in ambient conditions. Laser action is also reported for CaGa{sub 2}S{sub 4}:Dy{sup 3+} at 2.4 {micro}m, CaGa{sub 2}S{sub 4}:Dy{sup 3+} at 1.4 {micro}m, and KPb{sub 2}Cl{sub 5}:Nd{sup 3+} at 1.06 {micro}m. Both host materials have been fully characterized, including lifetimes, absorption and emission cross sections, radiative branching ratios, and radiative quantum efficiencies. Radiative branching ratios and radiative quantum efficiencies have been determined both by the Judd-Ofelt method (which is based on absorption measurements), and by a novel method described herein which is based on emission measurements. Modeling has been performed to predict laser performance, and a new method to determine emission cross section from slope efficiency and threshold data is developed. With the introduction and laser demonstration of rare-earth-doped CaGa{sub 2}S{sub 4} and KPb{sub 2}Cl{sub 5}, direct generation of mid-IR laser radiation in a solid-state host has been demonstrated. In

  4. Optical characterization of perturbed sites and C3i sites in rare earth doped oxide crystals

    NASA Astrophysics Data System (ADS)

    Reinemer, Gregoy Donald

    Energies, linewidths, and line strengths for some intrinsic and perturbed site transitions of seven different rare-earth ions doped into Y3Al 5O12 were measured as a function of concentration using visible and infrared absorption. Nearest and next-nearest neighbor ion pair transitions were characterized by their concentration dependence, and an analysis of Pr 3+ and Nd3+ pairs showed that those ions are distributed randomly in the lattice. For all transitions studied, the intrinsic D2 site and pair site transitions accounted for 92%--95% of the total line strength; the remaining 5%--8% was assigned to perturbed site transitions. No significant dependence of perturbed site line strength on ionic radius was observed. The nominally equal perturbed site line strength for all transitions studied implied that oscillator strengths for intrinsic and perturbed sites were similar. The perturbed sites appear to be a normal property of the Y3Al 5O12 lattice. To further investigate the nature of the perturbed sites, experiments were done showing that Er3+ occupies a site in Er3+ :Y3Al5O12 with a threefold axis along <111> that is consistent with occupation of the octahedral Al3+ site with C3i symmetry. Allowed magnetic dipole transitions at 1.5 microns were identified in the 4I15/2(1)→ 4I13/2 absorption spectrum using site selective fluorescence. Angle dependent Zeeman experiments on these transitions confirmed that they are from a site with a threefold axis along <111>. Using optical nutation experiments, the number density for Er 3+ C3i sites in 1.0 at.% Er3+:Y3Al 5O12 was determined to be (5 +/- 2) x 10 17 Er3+/cm3. Since Er3+ has nearly the same ionic radius as Y3+, the occupation of these same sites by Y3+ was deduced to be 0.6% +/- 0.3%. Assuming each Y3+ C3i site perturbs 12 D2 sites, the fractional line strength for perturbed sites would be 5% +/- 2%. Similar experiments on 0.05 at.% Er3+:Y2O 3 characterized C3i site Er3+ 4I 15/2 and 4I13/2 crystal field levels and g

  5. Demonstration of ultra-low NA rare-earth doped step index fiber for applications in high power fiber lasers.

    PubMed

    Jain, Deepak; Jung, Yongmin; Barua, Pranabesh; Alam, Shaiful; Sahu, Jayanta K

    2015-03-23

    In this paper, we report the mode area scaling of a rare-earth doped step index fiber by using low numerical aperture. Numerical simulations show the possibility of achieving an effective area of ~700 um² (including bend induced effective area reduction) at a bend diameter of 32 cm from a 35 μm core fiber with a numerical aperture of 0.038. An effective single mode operation is ensured following the criterion of the fundamental mode loss to be lower than 0.1 dB/m while ensuring the higher order modes loss to be higher than 10 dB/m at a wavelength of 1060 nm. Our optimized modified chemical vapor deposition process in conjunction with solution doping process allows fabrication of an Yb-doped step index fiber having an ultra-low numerical aperture of ~0.038. Experimental results confirm a Gaussian output beam from a 35 μm core fiber validating our simulation results. Fiber shows an excellent laser efficiency of ~81%and aM² less than 1.1. PMID:25837082

  6. Luminescence properties of barium--gadolinium-titanate ceramics doped with rare-earth ions (Eu3+ and Tb3+).

    PubMed

    Hemasundara Raju, S; Muni Sudhakar, B; Sudhakar Reddy, B; Dhoble, S J; Thyagarajan, K; Nageswara Raju, C

    2014-11-01

    Barium-gadolinium-titanate (BaGd2 Ti4 O12) powder ceramics doped with rare-earth ions (Eu(3+) and Tb(3+)) were synthesized by a solid-state reaction method. From the X-ray diffraction spectrum, it was observed that Eu(3+) and Tb(3+):BaGd2 Ti4 O12 powder ceramics are crystallized in the form of an orthorhombic structure. Scanning electron microscopy image shows that the particles are agglomerated and the particle size is about 200 nm. Eu(3+) - and Tb(3+) -doped BaGd2 Ti4 O12 powder ceramics were examined by energy dispersive X-ray analysis, Fourier transform infrared spectroscopy, photoluminescence and thermoluminescence (TL) spectra. Emission spectra of Eu(3+)-doped BaGd2 Ti4 O12 powder ceramics showed bright red emission at 613 nm ((5)D0 →(7)F2) with an excitation wavelength λ(exci)  = 408 nm ((7)F0 → (5)D3) and Tb(3+):BaGd2 Ti4 O12 ceramic powder has shown green emission at 534 nm ((5)D4 → (7)F5) with an excitation wavelength λ(exci)  = 331 nm (((7)F6 → (5)D1). TL spectra show that Eu(3+) and Tb(3+) ions affect TL sensitivity.

  7. Synthesis of rare earth doped TiO2 nanorods as photocatalysts for lignin degradation

    SciTech Connect

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; Moon, Ji-Won; Gu, Baohua; Wang, Wei

    2015-09-10

    In this paper, a two-step process is developed to synthesize rare earth doped titania nanorods (RE–TiO2 NRs) as photocatalysts for efficient degradation of lignin under simulated sunlight irradiation. In this approach, protonated titanate nanotubes with layered structures were first prepared by a hydrothermal approach, and rare earth metal ions were subsequently bound to the negatively charged surface of the synthesized titanate via electrostatic incorporation. The as-synthesized RE–TiO2 NRs after calcination generally showed much higher photocatalytic efficiencies than those of undoped TiO2 NRs or the commercial P25 TiO2 photocatalyst. Using methyl orange (MO) as a probing molecule, we demonstrate that Eu–TiO2 NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10-3 s-1. The La3+, Sm3+, Eu3+ and Er3+ doped TiO2 NRs also showed higher photocatalytic efficiencies in degrading MO than the commercial P25 TiO2. Finally, we further demonstrate that lignin can be photodegraded effectively and rapidly at room temperature under simulated sunlight through two reaction routes, which could be important in controlling ways of lignin depolymerization or the formation of reaction products.

  8. An Integrated and Collaborative Approach for NASA Earth Science Data

    NASA Technical Reports Server (NTRS)

    Murphy, K.; Lowe, D.; Behnke, J.; Ramapriyan, H.; Behnke, J.; Sofinowski, E.

    2012-01-01

    Earth science research requires coordination and collaboration across multiple disparate science domains. Data systems that support this research are often as disparate as the disciplines that they support. These distinctions can create barriers limiting access to measurements, which could otherwise enable cross-discipline Earth science. NASA's Earth Observing System Data and Information System (EOSDIS) is continuing to bridge the gap between discipline-centric data systems with a coherent and transparent system of systems that offers up to date and engaging science related content, creates an active and immersive science user experience, and encourages the use of EOSDIS earth data and services. The new Earthdata Coherent Web (ECW) project encourages cohesiveness by combining existing websites, data and services into a unified website with a common look and feel, common tools and common processes. It includes cross-linking and cross-referencing across the Earthdata site and NASA's Distributed Active Archive Centers (DAAC), and by leveraging existing EOSDIS Cyber-infrastructure and Web Service technologies to foster re-use and to reduce barriers to discovering Earth science data (http://earthdata.nasa.gov).

  9. Investigation of thermal diffusivity dependence on temperature in a group of optical single crystals doped with rare earth ions

    NASA Astrophysics Data System (ADS)

    Trefon-Radziejewska, D.; Bodzenta, J.

    2015-07-01

    The group of YAG, YVO4 and GdCOB single crystals was examined to determine the thermal diffusivity as a function of temperature in range from 30 °C to 300 °C. Further investigations concerned on analysis of the influence of dopants on these dependencies. The experimental setup based on thermal wave method with mirage detection was used. The samples represented different crystallographic systems such as cubic (YAG) tetragonal (YVO4) and monoclinic (GdCOB). The anisotropy of thermal conductivity of investigated samples was taken into account in the investigations. The crystals were doped with calcium ions, rare earth ions such as ytterbium, neodymium, and thulium, and also with transition metal vanadium. The results confirmed that influence of doping on the thermal diffusivity of investigated materials strongly depends on temperature. In general the thermal diffusivity decreases with increasing of sample temperature from 30 °C to 300 °C, however the drop in thermal diffusivity is the highest for pure single crystals. Doping is another factor reducing the heat transport in single crystals. Introduction of dopant ions into a crystal lattice leads to a significant decrease in the thermal diffusivity at lower temperatures in comparison with pure crystals. However, the influence of dopants becomes less pronounced with increasing temperature, and in case of weakly doped crystals it becomes negligible at higher temperatures. The interpretation of thermal diffusivity dependence on temperature for single crystals was based on the Debye model of lattice thermal conductivity of solids. The results allowed to conclude that the decrease of thermal diffusivity with temperature and increasing concentration of impurities is caused by shortening of the phonons mean free path due to phonon-phonon and phonon-point defect scatterings.

  10. Earth

    NASA Technical Reports Server (NTRS)

    Carr, M. H.

    1984-01-01

    The following aspects of the planet Earth are discussed: plate tectonics, the interior of the planet, the formation of the Earth, and the evolution of the atmosphere and hydrosphere. The Earth's crust, mantle, and core are examined along with the bulk composition of the planet.

  11. The Role of Defect Complexes in the Magneto-Optical Properties of Rare Earth Doped Gallium Nitride

    NASA Astrophysics Data System (ADS)

    Mitchell, Brandon

    Wide band gap semiconductors doped with rare earth ions (RE) have shown great potential for applications in optoelectronics, photonics, and spintronics. The 1.54mum Erbium (Er) emission has been extensively utilized in optical fiber communications, and Europium (Eu) is commonly used as a red color component for LEDs and fluorescence lamps. For the realization of spintronic-type devices, a dilutely doped semiconductor that exhibits room temperature ferromagnetic behavior would be desirable. Such behavior has been observed in GaN:Er. Furthermore, it was demonstrated that strain may play an important role in the control of this ferromagnetism; however, this requires further investigation. One motivation of this work is the realization of an all solid state white light source monolithically integrated into III/V nitride semiconductor materials, ideally GaN. For this, the current AlGaAs-based LEDs need to be replaced. One approach for achieving efficient red emission from GaN is dilute doping with fluorescent ions. In this regard, Eu has consistently been the most promising candidate as a dopant in the active layer for a red, GaN based, LED due to the sharp 5D0 to 7F2 transitions that result in red emission around 620nm. The success of GaN:Eu as the active layer for a red LED is based on the ability for the Eu ions to be efficiently excited by electron hole pairs. Thus, the processes by which energy is transferred from the host to the Eu ions has been studied. Complications arise, however, from the fact that Eu ions incorporate into multiple center environments, the structures of which are found to have a profound influence on the excitation pathways and efficiencies of the Eu ion. Therefore the nature of Eu incorporation and the resulting luminescence efficiency in GaN has been extensively investigated. By performing a comparative study on GaN:Eu samples grown under a variety of controlled conditions and using a variety of experimental techniques, the majority site has

  12. Light source with carbon nanotubes field emission cathode and rare-earth doped nanocrystalline phosphors

    NASA Astrophysics Data System (ADS)

    Psuja, P.; Strek, W.

    2007-09-01

    In this work we report a new carbon nanotubes field emission (CNT-FED) light source with nanocrystalline phosphors. The nanocrystalline powders of cerium doped yttrium aluminum garnet were obtained by modified Pechini method. The phosphor has been electrophoretically deposited on ITO-glass substrates. The cathode composed of carbon nanotubes was fabricated in the same manner. A light source was assembled and tested. Low-voltage cathodoluminescent spectra and I-V characteristics of fabricated cathodes were measured. A possibility of application of Ce doped nanocrystalline YAG phosphor in the field emission displays (FEDs) was discussed.

  13. Program for integrating multizonal photographs of the Earth, taken by MKF-6 camera, in a computer

    NASA Technical Reports Server (NTRS)

    Agapov, A. V.; Mosin, S. T.

    1980-01-01

    An algorithm and program are described, for integrating up to 6 simultaneously exposed photographs in different spectral ranges of the surface of the Earth, taken by MKF-6 cameras aboard Soyuz-22. Three of the reference marks are identified on 1 photograph and then are used to integrate the other photographs with the first. The program was compiled for the ES-1040 computer, as a standard subprogram in a system for computer processing of data of study of the Earth from space.

  14. Cerium-doped mixed-alkali rare-earth double-phosphate scintillators for x- and gamma-ray detection

    NASA Astrophysics Data System (ADS)

    Neal, John S.; Boatner, Lynn A.; Spurrier, Merry; Szupryczynski, Piotr; Melcher, Charles L.

    2006-08-01

    Previous measurements of the scintillation properties of members of the single-alkali, rare-earth double-phosphate family have demonstrated high light output and fast decay times when exposed to ionizing radiation. Cerium-doped K 3Lu(PO 4) II and Rb 3Lu(PO 4) II scintillators have exhibited light outputs of 32,500 and 28,200 photons/MeV respectively and decay times of 37 and 34 nanoseconds respectively. Because of the ease with which the alkali constituents (Li, Na, K, Rb, Cs) of the crystal matrix may be interchanged (e.g. K IICsLu(PO 4) II and CsLi IILu(PO 4) II), the rare-earth double-phosphate family of scintillators provides an ideal system for the study of matrix effects on scintillation efficiency and kinetics. In order to better understand and to ultimately optimize the scintillation properties of these scintillators, new members of the rare-earth double-phosphate family have been synthesized by high temperature flux growth. These new samples, represented by the general formula (A,B) 3Lu(PO 4) II:Ce where A and B are alkali elements, incorporate mixed alkali rather than single alkali components and varying levels of Ce doping. Light output, scintillation decay times, and photoluminescence measurements for the most promising of the samples to date are reported. In this paper, we identify promising samples and results that clearly demonstrate outstanding light output, up to 270% of BGO, fast decay times, 29-39 nanoseconds, and peak emission wavelengths of ~ 400 nm for many of the samples.

  15. Characterizing the Purple Earth: Modeling the Globally Integrated Spectral Variability of the Archean Earth

    NASA Astrophysics Data System (ADS)

    Sanromá, E.; Pallé, E.; Parenteau, M. N.; Kiang, N. Y.; Gutiérrez-Navarro, A. M.; López, R.; Montañés-Rodríguez, P.

    2014-01-01

    Ongoing searches for exoplanetary systems have revealed a wealth of planets with diverse physical properties. Planets even smaller than the Earth have already been detected and the efforts of future missions are aimed at the discovery, and perhaps characterization, of small rocky exoplanets within the habitable zone of their stars. Clearly, what we know about our planet will be our guideline for the characterization of such planets. However, the Earth has been inhabited for at least 3.8 Gyr and its appearance has changed with time. Here, we have studied the Earth during the Archean eon, 3.0 Gyr ago. At that time, one of the more widespread life forms on the planet was purple bacteria. These bacteria are photosynthetic microorganisms and can inhabit both aquatic and terrestrial environments. Here, we use a radiative transfer model to simulate the visible and near-infrared radiation reflected by our planet, taking into account several scenarios regarding the possible distribution of purple bacteria over continents and oceans. We find that purple bacteria have a reflectance spectrum that has a strong reflectivity increase, similar to the red edge of leafy plants, although shifted redward. This feature produces a detectable signal in the disk-averaged spectra of our planet, depending on cloud amount and purple bacteria concentration/distribution. We conclude that by using multi-color photometric observations, it is possible to distinguish between an Archean Earth in which purple bacteria inhabit vast extensions of the planet and a present-day Earth with continents covered by deserts, vegetation, or microbial mats.

  16. Characterizing the Purple Earth: Modeling the globally integrated spectral variability of the Archean Earth

    SciTech Connect

    Sanromá, E.; Pallé, E.; López, R.; Montañés-Rodríguez, P.; Kiang, N. Y.; Gutiérrez-Navarro, A. M.

    2014-01-01

    Ongoing searches for exoplanetary systems have revealed a wealth of planets with diverse physical properties. Planets even smaller than the Earth have already been detected and the efforts of future missions are aimed at the discovery, and perhaps characterization, of small rocky exoplanets within the habitable zone of their stars. Clearly, what we know about our planet will be our guideline for the characterization of such planets. However, the Earth has been inhabited for at least 3.8 Gyr and its appearance has changed with time. Here, we have studied the Earth during the Archean eon, 3.0 Gyr ago. At that time, one of the more widespread life forms on the planet was purple bacteria. These bacteria are photosynthetic microorganisms and can inhabit both aquatic and terrestrial environments. Here, we use a radiative transfer model to simulate the visible and near-infrared radiation reflected by our planet, taking into account several scenarios regarding the possible distribution of purple bacteria over continents and oceans. We find that purple bacteria have a reflectance spectrum that has a strong reflectivity increase, similar to the red edge of leafy plants, although shifted redward. This feature produces a detectable signal in the disk-averaged spectra of our planet, depending on cloud amount and purple bacteria concentration/distribution. We conclude that by using multi-color photometric observations, it is possible to distinguish between an Archean Earth in which purple bacteria inhabit vast extensions of the planet and a present-day Earth with continents covered by deserts, vegetation, or microbial mats.

  17. Low temperature glassy relaxation in rare earth doped Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Laha, Suvra; Lawes, Gavin

    2012-10-01

    Magnetic nanoparticles typically exhibit glassy relaxation at low temperature, which can be affected by doping. Gadolinium and Lanthanum doped Fe3O4 nanoparticles were synthesized using a chemical co-precipitation method. The structural and optical properties of these nanoparticles were characterized by using Transmission Electron Microscope (TEM) and the Raman spectroscopy. The TEM images show the formation of nanoparticles of size ranging between 12-14 nm and Raman spectra are consistent with the formation of Fe3O4. AC magnetic measurements were also conducted on these nanoparticles. From the ac out-of-phase susceptibility (χ//) vs temperature (T) graphs, it is observed that the doped nanoparticles show larger amplitude relaxation peaks at low temperature as compared to the undoped particles. These magnetic relaxation features develop roughly between 25K to 35K and show frequency dependence. The increased magnetic relaxation at low temperatures can be attributed to structural defects which may arise due to the doping of lanthanides in Fe3O4 nanoparticles.

  18. Effect of rare-earth doping in RCrSb3 (R = La, Pr, Sm, and Gd)

    SciTech Connect

    Jackson, D D; Fisk, Z

    2005-11-08

    We report on the electrical resistivity and magnetic susceptibility of La or Gd doped RCrSb{sub 3} (R=La, Pr, Sm, and Gd). Single crystals were grown by increasing the nominal dopant by 25%. In general, two magnetic ordering transitions are found, T{sub C1} is attributed to ferromagnetic ordering of the itinerant Cr sub-lattice, and, at lower temperatures, T{sub C2} is attributed to ordering of the localized rare-earth sub-lattice. Alloying on the rare-earth site varies the de Gennes factor, DG = (g-1){sup 2}J(J+1), and dT{sub C1}/d(DG) = -2K, while dT{sub C2}/d(DG) = 5K. These ordering temperatures are found to converge at GdCrSb{sub 3}, where a single ferrimagnetic transition is found at T{sub C2} = 86 K due to an anti-alignment of the itinerant Cr moments and the localized rare-earth moments. Initially, for DG < 3.5, the rare-earth moments are found to align ferromagnetically, and the paramagnetic Weiss temperature decreases at the same rate as T{sub C1}. But for DG > 4.5, the rare-earth sub-lattice anti-alignes with respect to the Cr sub-lattice, and the Weiss temperature decreases five times as fast. In the region between (3.5 < DG < 4.5), a first order phase transition is found at T{sub C2}.

  19. Novel rare earth ions-doped oxyfluoride nano-composite with efficient upconversion white-light emission

    SciTech Connect

    Chen Daqin; Wang Yuansheng Yu Yunlong; Huang Ping; Weng Fangyi

    2008-10-15

    Transparent SiO{sub 2}-Al{sub 2}O{sub 3}-NaF-YF{sub 3} bulk nano-composites triply doped with Ho{sup 3+}, Tm{sup 3+} and Yb{sup 3+} were fabricated by melt-quenching and subsequent heating. X-ray diffraction and transmission electron microscopy measurements demonstrated the homogeneous precipitation of the {beta}-YF{sub 3} crystals with mean size of 20 nm among the glass matrix, and rare earth ions were found to partition into these nano-crystals. Under single 976 nm laser excitation, intense red, green and blue upconversion emissions were simultaneously observed owing to the successive energy transfer from Yb{sup 3+} to Ho{sup 3+} or Tm{sup 3+}. Various colors of luminescence, including bright perfect white light, can be easily tuned by adjusting the concentrations of the rare earth ions in the material. The overall energy efficiency of the white-light upconversion was estimated to be about 0.2%. - Graphical abstract: Under single 976 nm laser excitation, intense red, green and blue upconversion emissions were simultaneously observed owing to the successive energy transfer from Yb{sup 3+} to Ho{sup 3+} or Tm{sup 3+}. Various colors of luminescence, including bright perfect white light with CIE-X=0.351 and CIE-Y=0.306, can be easily tuned by adjusting the concentrations of the rare earth ions in the transparent oxyfluoride glass ceramics.

  20. Transforming Water Management: an Emerging Promise of Integrated Earth Observations

    NASA Astrophysics Data System (ADS)

    Lawford, R. G.

    2011-12-01

    Throughout its history, civilization has relied on technology to facilitate many of its advances. New innovations and technologies have often provided strategic advantages that have led to transformations in institutions, economies and ultimately societies. Observational and information technologies are leading to significant developments in the water sector. After a brief introduction tracing the role of observational technologies in the areas of hydrology and water cycle science, this talk explores the existing and potential contributions of remote sensing data in water resource management around the world. In particular, it outlines the steps being undertaken by the Group on Earth Observations (GEO) and its Water Task to facilitate capacity building efforts in water management using Earth Observations in Asia, Africa and Latin and Caribbean America. Success stories on the benefits of using Earth Observations and applying GEO principles are provided. While GEO and its capacity building efforts are contributing to the transformation of water management through interoperability, data sharing, and capacity building, the full potential of these contributions has not been fully realized because impediments and challenges still remain.

  1. Earth Observation and GIS Services Integration Approach in MASS

    NASA Astrophysics Data System (ADS)

    Coene, Y.; Gianfranceschi, S.; Marchetti, P.

    This paper describes an environment for the integration of EO and GIS services supporting the provision of EO services and "information products" closer to customer expectations and processes. The paper explains how the adoption of readily available XML-based Web standards and protocols in an open environment can facilitate the integration.

  2. Bridging the Gap between Earth Science and Students: An Integrated Approach using NASA Earth Science Climate Data

    NASA Technical Reports Server (NTRS)

    Alston, Erica J.; Chambers, Lin H.; Phelps, Carrie S.; Oots, Penny C.; Moore, Susan W.; Diones, Dennis D.

    2007-01-01

    Under the auspices of the Department of Education's No Child Left Behind (NCLB) Act, beginning in 2007 students will be tested in the science area. There are many techniques that educators can employ to teach students science. The use of authentic materials or in this case authentic data can be an engaging alternative to more traditional methods. An Earth science classroom is a great place for the integration of authentic data and science concepts. The National Aeronautics and Space Administration (NASA) has a wealth of high quality Earth science data available to the general public. For instance, the Atmospheric Science Data Center (ASDC) at NASA s Langley Research Center houses over 800 Earth science data sets related to Earth's radiation budget, clouds, aerosols and tropospheric chemistry. These data sets were produced to increase academic understanding of the natural and anthropogenic factors that influence global climate; however, a major hurdle in using authentic data is the size of the data and data documentation. To facilitate the use of these data sets for educational purposes, the Mentoring and inquirY using NASA Data on Atmospheric and Earth science for Teachers and Amateurs (MY NASA DATA) project has been established to systematically support educational activities at all levels of formal and informal education. The MY NASA DATA project accomplishes this by reducing these large data holdings to microsets that are easily accessible and explored by K-12 educators and students though the project's Web page. MY NASA DATA seeks to ease the difficulty in understanding the jargon-heavy language of Earth science. This manuscript will show how MY NASA DATA provides resources for NCLB implementation in the science area through an overview of the Web site, the different microsets available, the lesson plans and computer tools, and an overview of educational support mechanisms.

  3. Estimation of cut-off wavelength of rare earth doped single-mode fibers

    NASA Astrophysics Data System (ADS)

    Kaur, Jagneet; Thyagarajan, K.; Pal, B. P.

    1999-11-01

    A new empirical relation is proposed describing spectral variation of mode-field radius (MFR) as inferred from measurements in the far-field of the fiber. It is shown that using this relation, it is possible to estimate the cut-off wavelength ( λc) of the fiber. The proposed technique is successfully tested through measurements made on two standard step index single-mode fibers, as well as on an erbium doped fiber (EDF) having λc falling within its strong absorption band around 980 nm. This empirical formula is more accurate than the widely used Marcuse's formula to describe spectral dependence of MFR determined through measurements made in the fiber's far-field. The proposed technique is especially suited for estimation of λc of doped fibers in which λc falls within an absorption band.

  4. Rare-earth doped transparent ceramics for spectral filtering and quantum information processing

    NASA Astrophysics Data System (ADS)

    Kunkel, Nathalie; Ferrier, Alban; Thiel, Charles W.; Ramírez, Mariola O.; Bausá, Luisa E.; Cone, Rufus L.; Ikesue, Akio; Goldner, Philippe

    2015-09-01

    Homogeneous linewidths below 10 kHz are reported for the first time in high-quality Eu3+ doped Y 2O3 transparent ceramics. This result is obtained on the 7F0→5D0 transition in Eu3+ doped Y 2O3 ceramics and corresponds to an improvement of nearly one order of magnitude compared to previously reported values in transparent ceramics. Furthermore, we observed spectral hole lifetimes of ˜15 min that are long enough to enable efficient optical pumping of the nuclear hyperfine levels. Additionally, different Eu3+ concentrations (up to 1.0%) were studied, resulting in an increase of up to a factor of three in the peak absorption coefficient. These results suggest that transparent ceramics can be useful in applications where narrow and deep spectral holes can be burned into highly absorbing lines, such as quantum information processing and spectral filtering.

  5. Up-conversion in rare earth-doped silica hollow spheres

    NASA Astrophysics Data System (ADS)

    Fortes, Luís M.; Li, Yigang; Réfega, Ricardo; Clara Gonçalves, M.

    2012-06-01

    In the present work, Er/Yb co-doped silica hollow spheres are prepared in a two-step process. In a first step, polystyrene-core is silica coated in situ by a modified Stöber sol-gel method and in the second one, the sacrificial polystyrene core is thermally removed. The core-shell and the hollow spheres are characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and photoluminescence spectroscopy (PL). PL measurements show up-conversion phenomena upon excitation at 975 nm, through the emission of blue (˜490 nm), green (˜523 nm and ˜536 nm) and red (˜655 nm) light. The up-conversion phenomena are discussed and modelled. The developed model explains the up-conversion phenomena of Er/Yb co-doped silica hollow spheres, with special agreement for high Yb/Er ratio.

  6. Role of vacancies, light elements and rare-earth metals doping in CeO2.

    PubMed

    Shi, H; Hussain, T; Ahuja, R; Kang, T W; Luo, W

    2016-01-01

    The magnetic properties and electronic structures of pure, doped and defective cerium oxide (CeO2) have been studied theoretically by means of ab initio calculations based on the density function theory (DFT) with the hybrid HF/DFT technique named PBE0. Carbon (C), nitrogen (N), phosphorus (P), sulphur (S), lanthanum (La) and praseodymium (Pr) doped in CeO2 and CeO2 containing oxygen vacancies (Ov) were considered. Our spin-polarized calculations show that C, N, Pr dopants and Ov defects magnetize the non-magnetic CeO2 in different degree. The optical band gap related to photocatalysis for pure CeO2, corresponding to the ultraviolet region, is reduced obviously by C, N, S, Pr impurities and oxygen vacancies, shifting to the visible region and even further to the infrared range. Especially, N-, S- and Pr-doped CeO2 could be used to photocatalytic water splitting for hydrogen production. As the concentration of Ov increasing up to 5%, the CeO2 exhibits a half-metallic properties. PMID:27554285

  7. White emission materials from glass doped with rare Earth ions: A review

    NASA Astrophysics Data System (ADS)

    Yasaka, P.; Kaewkhao, J.

    2016-03-01

    Solid State Lighting (SSL) based devices are predicted to play a crucial role in the coming years. Development of W-LED, which have an edge over traditional lighting sources due to their compact size, higher reliability, shock resistance, interesting design possibilities, higher transparency and an extremely long lifetime. Over the fifteen trivalent lanthanide ions, Dy3+ ions doped glasses are most appropriate for white light generation because of the fact that it exhibits two intense emission bands corresponds to the 4F9/2→6H15/2 (magnetic dipole) and 4F9/2→6H13/2 (electric dipole) transitions at around 480-500 nm and 580-600 nm pertaining to blue and yellow regions respectively. In this work, the developments of Dy3+ doped in several glass structures for white emitting materials application have reviewed. Properties of Dy3+ doped in glasses were discussed for use as a solid state lighting materials application.

  8. Role of vacancies, light elements and rare-earth metals doping in CeO2

    PubMed Central

    Shi, H.; Hussain, T.; Ahuja, R.; Kang, T. W.; Luo, W.

    2016-01-01

    The magnetic properties and electronic structures of pure, doped and defective cerium oxide (CeO2) have been studied theoretically by means of ab initio calculations based on the density function theory (DFT) with the hybrid HF/DFT technique named PBE0. Carbon (C), nitrogen (N), phosphorus (P), sulphur (S), lanthanum (La) and praseodymium (Pr) doped in CeO2 and CeO2 containing oxygen vacancies (Ov) were considered. Our spin-polarized calculations show that C, N, Pr dopants and Ov defects magnetize the non-magnetic CeO2 in different degree. The optical band gap related to photocatalysis for pure CeO2, corresponding to the ultraviolet region, is reduced obviously by C, N, S, Pr impurities and oxygen vacancies, shifting to the visible region and even further to the infrared range. Especially, N-, S- and Pr-doped CeO2 could be used to photocatalytic water splitting for hydrogen production. As the concentration of Ov increasing up to 5%, the CeO2 exhibits a half-metallic properties. PMID:27554285

  9. Role of vacancies, light elements and rare-earth metals doping in CeO2.

    PubMed

    Shi, H; Hussain, T; Ahuja, R; Kang, T W; Luo, W

    2016-08-24

    The magnetic properties and electronic structures of pure, doped and defective cerium oxide (CeO2) have been studied theoretically by means of ab initio calculations based on the density function theory (DFT) with the hybrid HF/DFT technique named PBE0. Carbon (C), nitrogen (N), phosphorus (P), sulphur (S), lanthanum (La) and praseodymium (Pr) doped in CeO2 and CeO2 containing oxygen vacancies (Ov) were considered. Our spin-polarized calculations show that C, N, Pr dopants and Ov defects magnetize the non-magnetic CeO2 in different degree. The optical band gap related to photocatalysis for pure CeO2, corresponding to the ultraviolet region, is reduced obviously by C, N, S, Pr impurities and oxygen vacancies, shifting to the visible region and even further to the infrared range. Especially, N-, S- and Pr-doped CeO2 could be used to photocatalytic water splitting for hydrogen production. As the concentration of Ov increasing up to 5%, the CeO2 exhibits a half-metallic properties.

  10. Role of vacancies, light elements and rare-earth metals doping in CeO2

    NASA Astrophysics Data System (ADS)

    Shi, H.; Hussain, T.; Ahuja, R.; Kang, T. W.; Luo, W.

    2016-08-01

    The magnetic properties and electronic structures of pure, doped and defective cerium oxide (CeO2) have been studied theoretically by means of ab initio calculations based on the density function theory (DFT) with the hybrid HF/DFT technique named PBE0. Carbon (C), nitrogen (N), phosphorus (P), sulphur (S), lanthanum (La) and praseodymium (Pr) doped in CeO2 and CeO2 containing oxygen vacancies (Ov) were considered. Our spin-polarized calculations show that C, N, Pr dopants and Ov defects magnetize the non-magnetic CeO2 in different degree. The optical band gap related to photocatalysis for pure CeO2, corresponding to the ultraviolet region, is reduced obviously by C, N, S, Pr impurities and oxygen vacancies, shifting to the visible region and even further to the infrared range. Especially, N-, S- and Pr-doped CeO2 could be used to photocatalytic water splitting for hydrogen production. As the concentration of Ov increasing up to 5%, the CeO2 exhibits a half-metallic properties.

  11. Effect of temperature and rare-earth doping on charge-carrier mobility in indium-monoselenide crystals

    SciTech Connect

    Abdinov, A. Sh.; Babayeva, R. F.; Amirova, S. I.; Rzayev, R. M.

    2013-08-15

    In the temperature range T = 77-600 K, the dependence of the charge-carrier mobility ({mu}) on the initial dark resistivity is experimentally investigated at 77 K ({rho}d{sub 0}), as well as on the temperature and the level (N) of rare-earth doping with such elements as gadolinium (Gd), holmium (Ho), and dysprosium (Dy) in n-type indium-monoselenide (InSe) crystals. It is established that the anomalous behavior of the dependences {mu}(T), {mu}({rho}d{sub 0}), and {mu}(N) found from the viewpoint of the theory of charge-carrier mobility in crystalline semiconductors is related, first of all, to partial disorder in indium-monoselenide crystals and can be attributed to the presence of random drift barriers in the free energy bands.

  12. Physical and optical absorption studies of Fe3+ - ions doped lithium borate glasses containing certain alkaline earths

    NASA Astrophysics Data System (ADS)

    Bhogi, Ashok; Kumar, R. Vijaya; Kistaiah, P.

    2016-05-01

    Iron ion doped lithium borate glasses with the composition 15RO-25Li2O-59B2O3-1Fe2O3 (where R= Ca, Sr and Ba) have been prepared by the conventional melt quenching technique and characterized to investigate the physical and optical properties using XRD, density, molar volume and UV-Visible spectroscopy. The optical absorption spectra exhibit a band at around 460 nm which is assigned to 6A1g(S) → 4Eg (G) of Fe3+ ions with distorted octahedral symmetry. From ultraviolet absorption edges, the optical band gap and Urbach energies have been evaluated. The effect of alkaline earths on these properties is discussed.

  13. Synthesis and optical characterizations of undoped and rare-earth-doped CaF{sub 2} nanoparticles

    SciTech Connect

    Bensalah, A. . E-mail: amina-bensalah@enscp.fr; Mortier, M.; Patriarche, G.; Gredin, P.; Vivien, D.

    2006-08-15

    The synthesis of undoped as well as Yb or Er-doped CaF{sub 2} nanocrystals using a reverse micelle method is reported. X-ray powder diffraction and transmission electron microscopy analysis showed that the products were single phased and rather monodispersed with an average particles size around 20 nm. The emission spectra and fluorescence decay times of both Yb{sup 3+} and Er{sup 3+} rare earths (RE) ions in CaF{sub 2} nanoparticles are presented. The particles size is increased by heating the as-obtained nanoparticles at different temperatures. The effect of annealing on the optical properties of the two RE ions in CaF{sub 2} is also investigated. - Graphical abstract: Transmission Electron Microscopy micrograph of CaF{sub 2} nanoparticles synthesized by a reverse-micelle method.

  14. Cyberinfrastructure at IRIS: Challenges and Solutions Providing Integrated Data Access to EarthScope and Other Earth Science Data

    NASA Astrophysics Data System (ADS)

    Ahern, T. K.; Barga, R.; Casey, R.; Kamb, L.; Parastatidis, S.; Stromme, S.; Weertman, B. T.

    2008-12-01

    While mature methods of accessing seismic data from the IRIS DMC have existed for decades, the demands for improved interdisciplinary data integration call for new approaches. Talented software teams at the IRIS DMC, UNAVCO and the ICDP in Germany, have been developing web services for all EarthScope data including data from USArray, PBO and SAFOD. These web services are based upon SOAP and WSDL. The EarthScope Data Portal was the first external system to access data holdings from the IRIS DMC using Web Services. EarthScope will also draw more heavily upon products to aid in cross-disciplinary data reuse. A Product Management System called SPADE allows archive of and access to heterogeneous data products, presented as XML documents, at the IRIS DMC. Searchable metadata are extracted from the XML and enable powerful searches for products from EarthScope and other data sources. IRIS is teaming with the External Research Group at Microsoft Research to leverage a powerful Scientific Workflow Engine (Trident) and interact with the web services developed at centers such as IRIS to enable access to data services as well as computational services. We believe that this approach will allow web- based control of workflows and the invocation of computational services that transform data. This capability will greatly improve access to data across scientific disciplines. This presentation will review some of the traditional access tools as well as many of the newer approaches that use web services, scientific workflow to improve interdisciplinary data access.

  15. Optical properties and size distribution of the nanocolloids made of rare-earth ion-doped NaYF4

    NASA Astrophysics Data System (ADS)

    Patel, Darayas N.; Lewis, Ashley; Wright, Donald M.; Lewis, Danielle; Valentine, Rueben; Valentine, Maucus; Wessley, Dennis; Sarkisov, Sergey; Darwish, Abdalla M.

    2015-03-01

    In this paper we investigate optical properties and size distribution of the nano-colloids made of trivalent rare-earth ion doped fluorides: holmium and ytterbium, thulium and ytterbium, and erbium and ytterbium co-doped NaYF4. These materials were synthesized by using simple co-precipitation synthetic method. The initially prepared micro-crystals had very weak or no visible upconversion fluorescence signals when being pumped with a 980-nm laser. The fluorescence intensity significantly increased after the crystals were annealed at a temperature of 400°C - 600°C undergoing the transition from cubic alpha to hexagonal beta phase of the fluoride host. Nano-colloids of the crystals were made in polar solvents using the laser ablation and ball milling methods. Size analyses of the prepared nano-colloids were conducted using a dynamic light scatterometer and atomic force microscope. The nano-colloids were filled in holey PCFs and their fluorescent properties were studied and the feasibility of new a type of fiber amplifier/laser was evaluated.

  16. Effect of rare earth radius and concentration on the structural and transport properties of doped Mn Zn ferrite

    NASA Astrophysics Data System (ADS)

    Ateia, E.; Ahmed, M. A.; El-Aziz, A. K.

    2007-04-01

    Dielectric constant ( ɛ'), AC conductivity ( σ), and seebeck coefficient ( S) have been measured for the ferrite samples of the general formula Mn 0.5Zn 0.5R yFe 2O 4; where R=Dy, Gd, Sm, Ce, and La prepared by standard ceramic technique and sintered at 1200 °C with a heating rate 4 °C/min. X-ray diffractograms show that all samples posses the spinel structure with the appearance of small peaks representing secondary phases. There is a lowering in the porosity starting after Sm-doped samples due to the presence of the secondary phases, which limits the grain growth. Due to seebeck measurements the manganese-zinc (Mn-Zn) ferrite doped with the rare earth has been classified as P-type semiconductors. It is possible to increase the electrical resistivity by using a small quantity of Dy 3+ ions substitutions owing to the structural heterogeneity generated by the insulating intergranular layers. The isolation of the grains is the most promising approaches for further reduction in the eddy current losses at the operating frequencies.

  17. Effects of rare earth ionic doping on microstructures and electrical properties of CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics

    SciTech Connect

    Xue, Renzhong; Chen, Zhenping; Dai, Haiyang; Liu, Dewei; Li, Tao; Zhao, Gaoyang

    2015-06-15

    Graphical abstract: The dielectric constant decreases monotonically with reduced RE doping ion radius and is more frequency independent compared with that of pure CCTO sample. - Highlights: • The mean grain sizes decrease monotonically with reduced RE doping ionic radius. • Doping gives rise to the monotonic decrease of ϵ{sub r} with reduced RE ionic radius. • The nonlinear coefficient and breakdown field increase with RE ionic doping. • α of all the samples is associated with the potential barrier width rather than Φ{sub b}. - Abstract: Ca{sub 1–x}R{sub x}Cu{sub 3}Ti{sub 4}O{sub 12}(R = La, Nd, Eu, Gd, Er; x = 0 and 0.005) ceramics were prepared by the conventional solid-state method. The influences of rare earth (RE) ion doping on the microstructure, dielectric and electrical properties of CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) ceramics were investigated systematically. Single-phase formation is confirmed by XRD analyses. The mean grain size decreases monotonically with reduced RE ion radius. The EDS results reveal that RE ionic doping reduces Cu-rich phase segregation at the grain boundaries (GBs). Doping gives rise to the monotonic decrease of dielectric constant with reduced RE ionic radius but significantly improves stability with frequency. The lower dielectric loss of doped samples is obtained due to the increase of GB resistance. In addition, the nonlinear coefficient and breakdown field increase with RE ionic doping. Both the fine grains and the enhancement of potential barrier at GBs are responsible for the improvement of the nonlinear current–voltage properties in doped CCTO samples.

  18. Rare-earth-doped materials with application to optical signal processing, quantum information science, and medical imaging technology

    NASA Astrophysics Data System (ADS)

    Cone, R. L.; Thiel, C. W.; Sun, Y.; Böttger, Thomas; Macfarlane, R. M.

    2012-02-01

    Unique spectroscopic properties of isolated rare earth ions in solids offer optical linewidths rivaling those of trapped single atoms and enable a variety of recent applications. We design rare-earth-doped crystals, ceramics, and fibers with persistent or transient "spectral hole" recording properties for applications including high-bandwidth optical signal processing where light and our solids replace the high-bandwidth portion of the electronics; quantum cryptography and information science including the goal of storage and recall of single photons; and medical imaging technology for the 700-900 nm therapeutic window. Ease of optically manipulating rare-earth ions in solids enables capturing complex spectral information in 105 to 108 frequency bins. Combining spatial holography and spectral hole burning provides a capability for processing high-bandwidth RF and optical signals with sub-MHz spectral resolution and bandwidths of tens to hundreds of GHz for applications including range-Doppler radar and high bandwidth RF spectral analysis. Simply stated, one can think of these crystals as holographic recording media capable of distinguishing up to 108 different colors. Ultra-narrow spectral holes also serve as a vibration-insensitive sub-kHz frequency reference for laser frequency stabilization to a part in 1013 over tens of milliseconds. The unusual properties and applications of spectral hole burning of rare earth ions in optical materials are reviewed. Experimental results on the promising Tm3+:LiNbO3 material system are presented and discussed for medical imaging applications. Finally, a new application of these materials as dynamic optical filters for laser noise suppression is discussed along with experimental demonstrations and theoretical modeling of the process.

  19. Novel kinds of down/up-conversion luminescent rare earth doped fluoride BaMgF{sub 4}: RE{sup 3+} microcrystals

    SciTech Connect

    Yan, Zhi-Yuan; Yan, Bing Jia, Li-Ping

    2013-10-15

    Graphical abstract: We achieve the liquid phase chemical synthesis of rare earth fluoride system BaMgF4: RE{sup 3+} microphosphors, which realize down/up-conversion luminescence. - Highlights: • Doped BaMgF{sub 4} microphosphors are firstly prepared by hydrothermal process. • Doped BaMgF{sub 4} nanosheets are firstly prepared by high temperature solution reaction. • The down-conversion luminescence is realized in the rare earth doped BaMgF{sub 4}. • The upconversion luminescence is realized in the rare earth doped BaMgF{sub 4}. - Abstract: In this paper, we realize the liquid-phase chemical synthesis of high-quality orthorhombic polycrystalline BaMgF{sub 4}: RE{sup 3+} (RE = Eu, Tb, Sm, Dy, Yb–Er/Tm) compounds with hydrothermal and high-temperature solution methods, respectively. The products from hydrothermal technology show the micrometer size while the products from hydrothermal technology present nanosheet morphology. The rare earth ions doped BaMgF{sub 4} from hydrothermal synthesis are discussed in details, which can realize the downconversion luminescence for doped Eu{sup 3+} or Tb{sup 3+} and upconversion luminescence for Yb{sup 3+}/Er{sup 3+} (Tm{sup 3+}), respectively. To our knowledge, the hydrothermal or high temperature solution synthesis and photoluminescence (Eu{sup 3+}, Tb{sup 3+} or Yb{sup 3+}/Er{sup 3+}(Tm{sup 3+})) of these fluoride systems are firstly reported.

  20. Integration of Earth System Models and Workflow Management under iRODS for the Northeast Regional Earth System Modeling Project

    NASA Astrophysics Data System (ADS)

    Lengyel, F.; Yang, P.; Rosenzweig, B.; Vorosmarty, C. J.

    2012-12-01

    The Northeast Regional Earth System Model (NE-RESM, NSF Award #1049181) integrates weather research and forecasting models, terrestrial and aquatic ecosystem models, a water balance/transport model, and mesoscale and energy systems input-out economic models developed by interdisciplinary research team from academia and government with expertise in physics, biogeochemistry, engineering, energy, economics, and policy. NE-RESM is intended to forecast the implications of planning decisions on the region's environment, ecosystem services, energy systems and economy through the 21st century. Integration of model components and the development of cyberinfrastructure for interacting with the system is facilitated with the integrated Rule Oriented Data System (iRODS), a distributed data grid that provides archival storage with metadata facilities and a rule-based workflow engine for automating and auditing scientific workflows.

  1. Micro Infrared Earth Sensor project: an integrated IR camera for Earth remote sensing

    NASA Astrophysics Data System (ADS)

    Soto-Romero, Georges; Bony, Francis; Simonne, Jean-Jacques; Fourniols, Jean-Yves

    2001-12-01

    MEMS technology now makes possible to produce active microdevices combining detection, signal processing, and data storage with accuracy and compactness. In view of their characteristics, it can be expected that such microsensors will be used extensively in space applications dedicated to micro and nano satellites. The advanced architecture of a MicroInfraRedEarthSensor generic system based on a Vox microbolometer array associated with optics and electronics 'on the shelves' for signal processing and depointing computation, used to control the attitude of satellites in low earth orbits, has been completely developed, through the design of a virtual prototype combined with a breadboard implementation of an IR camera (called MST, and has been developed by EADS-SODERN, in the frame of IASI project). The correlation of the virtual prototyping approach, has allowed to build one complete optical head part of the instrument with efficient and optimized parameters where the performances are consistent with the main mission specifications (pointing accuracy 10 Hz, aperture angle: > 36 degree(s), volume

  2. Rare earth-doped materials with enhanced thermoelectric figure of merit

    DOEpatents

    Venkatasubramanian, Rama; Cook, Bruce Allen; Levin, Evgenii M.; Harringa, Joel Lee

    2016-09-06

    A thermoelectric material and a thermoelectric converter using this material. The thermoelectric material has a first component including a semiconductor material and a second component including a rare earth material included in the first component to thereby increase a figure of merit of a composite of the semiconductor material and the rare earth material relative to a figure of merit of the semiconductor material. The thermoelectric converter has a p-type thermoelectric material and a n-type thermoelectric material. At least one of the p-type thermoelectric material and the n-type thermoelectric material includes a rare earth material in at least one of the p-type thermoelectric material or the n-type thermoelectric material.

  3. Superposition-model analysis of rare-earth doped BaY2F8

    NASA Astrophysics Data System (ADS)

    Magnani, N.; Amoretti, G.; Baraldi, A.; Capelletti, R.

    The energy level schemes of four rare-earth dopants (Ce3+ , Nd3+ , Dy3+ , and Er3+) in BaY2 F-8 , as determined by optical absorption spectra, were fitted with a single-ion Hamiltonian and analysed within Newman's Superposition Model for the crystal field. A unified picture for the four dopants was obtained, by assuming a distortion of the F- ligand cage around the RE site; within the framework of the Superposition Model, this distortion is found to have a marked anisotropic behaviour for heavy rare earths, while it turns into an isotropic expansion of the nearest-neighbours polyhedron for light rare earths. It is also inferred that the substituting ion may occupy an off-center position with respect to the original Y3+ site in the crystal.

  4. Synthesis of rare earth doped yttrium-vanadate nanoparticles encapsulated within apoferritin.

    PubMed

    Harada, Tomoaki; Yoshimura, Hideyuki

    2014-07-28

    Luminescent europium (Eu) and dysprosium (Dy) doped yttrium-vanadate (Y-V) nanoparticles (NPs) were synthesized in the cavity of the protein, apoferritin. Y-V NPs were synthesized by incubating a solution of apoferritin with Y(3+) and VO3(-) ions in the presence of ethylene diamine-N-N'-diacetic acid (EDDA). EDDA plays an important role in preventing Y-vanadate precipitation in bulk solution by chelating the Y(3+) ions. Using high resolution electron microscopy, the obtained NPs in the apoferritin cavities were confirmed to be amorphous, and to consist of Y and V. Eu-doped Y-V (Y-V:Eu) NPs were synthesized by the same procedure as Y-V NPs, except that Eu(NO3)3 was added. Y-V:Eu NPs exhibited a strong absorption peak due to the O-V charge transfer transition and remarkable luminescence at 618 nm due to the (5)D0 → (7)F2 transition. The luminescence lifetime of Y:Eu and Y-V:Eu NPs measured in H2O and D2O solution showed reduction of non-radiative transition to the O-H vibration in Y-V:Eu NPs. Accordingly, Y-V NPs showed strong luminescence compared to Y:Eu NPs. Dy-doped Y-V NPs were also synthesized in apoferritin cavities and showed luminescence peaks at 482 nm and 572 nm, corresponding to (4)F9/2 → (6)H15/2 and (4)F9/2 → (6)H13/2 transitions. These NPs stably dispersed in water solution since their aggregation was prevented by the protein shell. NPs encapsulated in the protein are likely to be biocompatible and would have significant potential for biological imaging applications.

  5. Effects of rare-earth doping on femtosecond laser waveguide writing in zinc polyphosphate glass

    SciTech Connect

    Fletcher, Luke B.; Witcher, Jon J.; Troy, Neil; Krol, Denise M.; Reis, Signo T.; Brow, Richard K.

    2012-07-15

    We have investigated waveguide writing in Er-Yb doped zinc polyphosphate glass using a femtosecond laser with a repetition rate of 1 KHz. We find that fabrication of good waveguides requires a glass composition with an O/P ratio of 3.25. The dependence on laser writing parameters including laser fluence, focusing conditions, and scan speed is reported. Waveguide properties together with absorption and emission data indicate that these glasses can be used for the fabrication of compact, high gain amplifying devices.

  6. Effects of rare-earth doping on femtosecond laser waveguide writing in zinc polyphosphate glass

    NASA Astrophysics Data System (ADS)

    Fletcher, Luke B.; Witcher, Jon J.; Troy, Neil; Reis, Signo T.; Brow, Richard K.; Krol, Denise M.

    2012-07-01

    We have investigated waveguide writing in Er-Yb doped zinc polyphosphate glass using a femtosecond laser with a repetition rate of 1 KHz. We find that fabrication of good waveguides requires a glass composition with an O/P ratio of 3.25. The dependence on laser writing parameters including laser fluence, focusing conditions, and scan speed is reported. Waveguide properties together with absorption and emission data indicate that these glasses can be used for the fabrication of compact, high gain amplifying devices.

  7. Integrating Diverse Geophysical and Geological Data to Construct Multi-Dimensional Earth Models: The Open Earth Framework

    NASA Astrophysics Data System (ADS)

    Baru, C.; Keller, R.; Wallet, B.; Crosby, C.; Moreland, J.; Nadeau, D.

    2008-12-01

    Currently, many large geoscientific efforts (e.g., EarthScope, Continental Dynamics, and GeoSwath) have emphasized that a crucial need in advancing our understanding of the structure and evolution of the continents is high-resolution, 3-D models of lithospheric structure. In addition, the geoscience community recognizes that our ultimate goal is the addition of the dimension of time to make the problem 4-D. Adding the dimension of time is a complex problem that is strongly dependent on the integration of a variety of geological data into our analyses (e.g., geochronology, paleontology, stratigraphy, pressure-time histories, structural geology, paleogeography, etc.). The geoscience community also recognizes that solutions to the scientific and societal questions that they seek to answer require innovative integration of many types of data so that many physical properties (x, y, z, P-wave velocity, S-wave velocity, density, electrical conductivity, etc.) are measured and included in 3-D models. The problem is, therefore, truly multidimensional in nature. We are developing an Open Earth Framework (OEF) as an open data model for integration of such multidimensional Earth Sciences data. In our work and interactions with the community on building and visualizing complex earth models, several issues have emerged on which there is consensus. First of all, integration efforts should work from the surface down because we have the most data there (e.g., geologic maps, remote sensing data such as LIDAR and ASTER, digital elevation models, gravity and magnetic measurements, etc.) and because the complex conditions near surface always have a potential to mask deeper features. Secondly since we cannot expect uniform coverage of a variety of high-resolution data in anything but special circumstances, a data integration effort should first establish a regional context using lower resolution (and usually wide coverage) data and then proceed to modeling the data sets with the highest

  8. Integrated Modular Avionics for Spacecraft: Earth Observation Use Case Demonstrator

    NASA Astrophysics Data System (ADS)

    Deredempt, Marie-Helene; Rossignol, Alain; Hyounet, Philippe

    2013-08-01

    Integrated Modular Avionics (IMA) for Space, as European Space Agency initiative, aimed to make applicable to space domain the time and space partitioning concepts and particularly the ARINC 653 standard [1][2]. Expected benefits of such an approach are development flexibility, capability to provide differential V&V for different criticality level functionalities and to integrate late or In-Orbit delivery. This development flexibility could improve software subcontracting, industrial organization and software reuse. Time and space partitioning technique facilitates integration of software functions as black boxes and integration of decentralized function such as star tracker in On Board Computer to save mass and power by limiting electronics resources. In aeronautical domain, Integrated Modular Avionics architecture is based on a network of LRU (Line Replaceable Unit) interconnected by AFDX (Avionic Full DupleX). Time and Space partitioning concept is applicable to LRU and provides independent partitions which inter communicate using ARINC 653 communication ports. Using End System (LRU component) intercommunication between LRU is managed in the same way than intercommunication between partitions in LRU. In such architecture an application developed using only communication port can be integrated in an LRU or another one without impacting the global architecture. In space domain, a redundant On Board Computer controls (ground monitoring TM) and manages the platform (ground command TC) in terms of power, solar array deployment, attitude, orbit, thermal, maintenance, failure detection and recovery isolation. In addition, Payload units and platform units such as RIU, PCDU, AOCS units (Star tracker, Reaction wheels) are considered in this architecture. Interfaces are mainly realized through MIL-STD-1553B busses and SpaceWire and this could be considered as the main constraint for IMA implementation in space domain. During the first phase of IMA SP project, ARINC653

  9. Laser-induced generation of micrometer-sized luminescent patterns on rare-earth-doped amorphous films

    SciTech Connect

    Zanatta, A.R.; Ribeiro, C.T.M.

    2004-12-01

    Room-temperature photoluminescence has been achieved from rare-earth-doped amorphous (a-) GeN films. The samples were prepared by the radio-frequency-sputtering method, and light emission from the rare-earth (RE) centers was obtained after irradiating the films with a highly focused laser beam. As a result of this laser annealing procedure, almost circular holes with approximately 1-{mu}m diameter were produced on the surface of the a-GeN films. The area nearby these holes correspond to crystalline Ge and coincide with the regions, where relatively strong RE-related luminescence takes place. These laser-annealed areas can be easily and conveniently managed in order to generate different microscopic luminescent patterns. Depending on the RE ion employed, visible and near-infrared light emission were obtained from the patterns so produced. The development of these micrometer-sized luminescent centers, as well as their probable mechanisms of excitation-recombination, will be presented and discussed. The importance of the current experimental results to future technological applications such as microdevices, for example, will also be outlined.

  10. Monolithic integration of rare-earth oxides and semiconductors for on-silicon technology

    SciTech Connect

    Dargis, Rytis Clark, Andrew; Erdem Arkun, Fevzi; Grinys, Tomas; Tomasiunas, Rolandas; O'Hara, Andy; Demkov, Alexander A.

    2014-07-01

    Several concepts of integration of the epitaxial rare-earth oxides into the emerging advanced semiconductor on silicon technology are presented. Germanium grows epitaxially on gadolinium oxide despite lattice mismatch of more than 4%. Additionally, polymorphism of some of the rare-earth oxides allows engineering of their crystal structure from hexagonal to cubic and formation of buffer layers that can be used for growth of germanium on a lattice matched oxide layer. Molecular beam epitaxy and metal organic chemical vapor deposition of gallium nitride on the rare-earth oxide buffer layers on silicon is discussed.

  11. Integrated planning and scheduling for Earth science data processing

    NASA Technical Reports Server (NTRS)

    Boddy, Mark; White, Jim; Goldman, Robert; Short, Nick, Jr.

    1995-01-01

    Several current NASA programs such as the EOSDIS Core System (ECS) have data processing and data management requirements that call for an integrated planning and scheduling capability. In this paper, we describe the experience of applying advanced scheduling technology operationally, in terms of what was accomplished, lessons learned, and what remains to be done in order to achieve similar successes in ECS and other programs. We discuss the importance and benefits of advanced scheduling tools, and our progress toward realizing them, through examples and illustrations based on ECS requirements. The first part of the paper focuses on the Data Archive and Distribution (DADS) V0 Scheduler. We then discuss system integration issues ranging from communication with the scheduler to the monitoring of system events and re-scheduling in response to them. The challenge of adapting the scheduler to domain-specific features and scheduling policies is also considered. Extrapolation to the ECS domain raises issues of integrating scheduling with a product-generation planner (such as PlaSTiC), and implementing conditional planning in an operational system. We conclude by briefly noting ongoing technology development and deployment projects being undertaken by HTC and the ISTB.

  12. Rare-earth doped transparent ceramics for spectral filtering and quantum information processing

    SciTech Connect

    Kunkel, Nathalie Goldner, Philippe; Ferrier, Alban; Thiel, Charles W.; Cone, Rufus L.; Ramírez, Mariola O.; Bausá, Luisa E.; Ikesue, Akio

    2015-09-01

    Homogeneous linewidths below 10 kHz are reported for the first time in high-quality Eu{sup 3+} doped Y {sub 2}O{sub 3} transparent ceramics. This result is obtained on the {sup 7}F{sub 0}→{sup 5}D{sub 0} transition in Eu{sup 3+} doped Y {sub 2}O{sub 3} ceramics and corresponds to an improvement of nearly one order of magnitude compared to previously reported values in transparent ceramics. Furthermore, we observed spectral hole lifetimes of ∼15 min that are long enough to enable efficient optical pumping of the nuclear hyperfine levels. Additionally, different Eu{sup 3+} concentrations (up to 1.0%) were studied, resulting in an increase of up to a factor of three in the peak absorption coefficient. These results suggest that transparent ceramics can be useful in applications where narrow and deep spectral holes can be burned into highly absorbing lines, such as quantum information processing and spectral filtering.

  13. Low-temperature thermoluminescence spectra of rare-earth-doped lanthanum fluoride

    SciTech Connect

    Yang, B.; Townsend, P.D.; Rowlands, A.P.

    1998-01-01

    Lanthanum fluoride consistently shows two strong thermoluminescence glow peaks at low temperature in pure material near 90 and 128 K. A model is proposed in which these thermoluminescence peaks arise from the annealing of halogen defect sites, similar to the H and V{sub k} centers of the alkali halides. Relaxation and decay of these defects in the pure LaF{sub 3} lattice results in broad-band intrinsic luminescence. Addition of rare-earth-impurity ions has two effects. First, the broad-band emission is replaced by narrow-band line emission defined by the trivalent rare-earth dopants. Second, it preferentially determines the formation of the halogen defect sites at impurity lattice sites and such sites appear to increase in thermal stability since the glow peak temperature increases from 128 K in the intrinsic material up to 141 K through the sequence of rare-earth dopants from La to Er. The temperature movement directly correlates with the changes in ionic size of the rare-earth ions, when allowance is made for differences in effective coordination number of the impurity ions. The data suggest two alternative lattice sites can be occupied. The model emphasizes that the intense thermoluminescence signals arise from internal charge rearrangements and annealing of defect complexes, rather than through the more conventional model of separated charge traps and recombination centers. At higher temperatures there is a complex array of glow peaks which depend not only on the dopant concentration but also are specific to each rare earth. Such effects imply defect models giving thermoluminescence within localized complexes and possible reasons are mentioned. {copyright} {ital 1998} {ital The American Physical Society}

  14. Cerium-doped mixed-alkali rare-earth double-phosphate scintillators for thermal neutron detection

    NASA Astrophysics Data System (ADS)

    Neal, John S.; Boatner, Lynn A.; Spurrier, Merry; Szupryczynski, Piotr; Melcher, Charles L.

    2007-08-01

    Previous measurements of the scintillation properties of members of the single-alkali, rare-earth double-phosphate family have demonstrated high light output and fast decay times when exposed to ionizing radiation. Because of the ease with which the alkali constituents (Li, Na, K, Rb, Cs) of the crystal matrix may be interchanged (e.g. K 2CsLu(PO 4) 2 and CsLi 2Lu(PO 4) 2), the rare-earth double-phosphate family of scintillators provides an ideal system for the study of matrix effects on scintillation efficiency and kinetics. New members of the rare-earth double-phosphate family have been synthesized by high-temperature flux growth. These new samples, represented by the general formula (A,B) 3Lu(PO 4) 2:Ce where A and B are alkali elements, incorporate lithium as one of the components and varying levels of Ce doping. Characteristics important to gamma-ray and thermal neutron excitation are calculated for three model systems which incorporate total lithium-ion substitution. Light output, scintillation decay times, and photoluminescence measurements for the most promising of the samples to date are reported. Future work includes (1) synthesis of mixed-alkali scandium and yttrium double-phosphates in which Li ions are substitutional in the structure with varying lithium-ion content up to and including total lithium-ion substitution on the alkali ion site and (2) measurements of light output and pulse shape using thermal neutron excitation.

  15. Rare-Earth Doped Particles as Dual-Modality Contrast Agent for Minimally-Invasive Luminescence and Dual-Wavelength Photoacoustic Imaging

    NASA Astrophysics Data System (ADS)

    Sheng, Yang; Liao, Lun-De; Thakor, Nitish; Tan, Mei Chee

    2014-10-01

    Multi-modal imaging is an emerging area that integrates multiple imaging modalities to simultaneously capture visual information over many spatial scales. Complementary contrast agents need to be co-developed in order to achieve high resolution and contrast. In this work, we demonstrated that rare-earth doped particles (REDPs) can be employed as dual-modal imaging agents for both luminescence and photoacoustic (PA) imaging to achieve intrinsic high contrast, temporal and spatial resolution, reaching deeper depth. REDPs synthesized with different surfactants (citric acid, polyacrylic acid, ethylenediaminetetraacetic acid and sodium citrate) exhibit tunable emission properties and PA signal amplitudes. Amongst these samples, sodium citrate-modified REDPs showed the strongest PA signals. Furthermore, since REDPs have multiple absorption peaks, they offer a unique opportunity for multi-wavelength PA imaging (e.g. PA signals were measured using 520 and 975 nm excitations). The in vivo PA images around the cortical superior sagittal sinus (SSS) blood vessel captured with enhanced signal arising from REDPs demonstrated that in addition to be excellent luminescent probes, REDPs can also be used as successful PA contrast agents. Anisotropic polyacrylic acid-modified REDPs were found to be the best candidates for dual-modal luminescence and PA imaging due to their strong luminescence and PA signal intensities.

  16. Rare-Earth Doped Particles as Dual-Modality Contrast Agent for Minimally-Invasive Luminescence and Dual-Wavelength Photoacoustic Imaging

    PubMed Central

    Sheng, Yang; Liao, Lun-De; Thakor, Nitish; Tan, Mei Chee

    2014-01-01

    Multi-modal imaging is an emerging area that integrates multiple imaging modalities to simultaneously capture visual information over many spatial scales. Complementary contrast agents need to be co-developed in order to achieve high resolution and contrast. In this work, we demonstrated that rare-earth doped particles (REDPs) can be employed as dual-modal imaging agents for both luminescence and photoacoustic (PA) imaging to achieve intrinsic high contrast, temporal and spatial resolution, reaching deeper depth. REDPs synthesized with different surfactants (citric acid, polyacrylic acid, ethylenediaminetetraacetic acid and sodium citrate) exhibit tunable emission properties and PA signal amplitudes. Amongst these samples, sodium citrate-modified REDPs showed the strongest PA signals. Furthermore, since REDPs have multiple absorption peaks, they offer a unique opportunity for multi-wavelength PA imaging (e.g. PA signals were measured using 520 and 975 nm excitations). The in vivo PA images around the cortical superior sagittal sinus (SSS) blood vessel captured with enhanced signal arising from REDPs demonstrated that in addition to be excellent luminescent probes, REDPs can also be used as successful PA contrast agents. Anisotropic polyacrylic acid-modified REDPs were found to be the best candidates for dual-modal luminescence and PA imaging due to their strong luminescence and PA signal intensities. PMID:25297843

  17. Photoluminescence of rare-earth ion (Eu3+, Tm3+, and Er3+)-doped and co-doped ZnNb2O6 for solar cells

    NASA Astrophysics Data System (ADS)

    Gao, Sen-Pei; Qian, Yan-Nan; Wang, Biao

    2015-08-01

    Visible converted emissions produced at an excitation of 286 nm in ZnNb2O6 ceramics doped with rare-earth ions (RE = Eu3+, Tm3+, Er3+ or a combination of these ions) were investigated with the aim of increasing the photovoltaic efficiency of solar cells. The structure of RE:ZnNb2O6 ceramics was confirmed by x-ray diffraction patterns. The undoped ZnNb2O6 could emit a blue emission under 286-nm excitation, which is attributed to the self-trapped excitons’ recombination of the efficient luminescence centers of edge-shared NbO6 groups. Upon 286-nm excitation, Eu:ZnNb2O6, Tm:ZnNb2O6, and Er:ZnNb2O6 ceramics showed blue, green, and red emissions, which correspond to the transitions of 5D0 → 7FJ (J = 1-4) (Eu3+), 1G4 → 3H6 (Tm3+), and 2H11/2/4S3/2 → 4I15/2 (Er3+), respectively. The calculated CIE chromaticity coordinates of Eu:ZnNb2O6, Tm:ZnNb2O6, and Er:ZnNb2O6 are (0.50, 0.31), (0.14, 0.19), and (0.29, 0.56), respectively. RE ion-co-doped ZnNb2O6 showed a combination of characteristic emissions. The chromaticity coordinates of Eu/Tm:ZnNb2O6, Eu/Er:ZnNb2O6, and Tm/Er:ZnNb2O6 were calculated to be (0.29, 0.24), (0.45, 0.37), and (0.17, 0.25). Project supported by the National Natural Science Foundation of China (Grant Nos. 10572155 and 10732100) and the Research Fund for the Doctoral Program of Ministry of Education, China (Grant No. 20130171130003).

  18. DECADE Web Portal: Integrating MaGa, EarthChem and GVP Will Further Our Knowledge on Earth Degassing

    NASA Astrophysics Data System (ADS)

    Cardellini, C.; Frigeri, A.; Lehnert, K. A.; Ash, J.; McCormick, B.; Chiodini, G.; Fischer, T. P.; Cottrell, E.

    2014-12-01

    The release of gases from the Earth's interior to the exosphere takes place in both volcanic and non-volcanic areas of the planet. Fully understanding this complex process requires the integration of geochemical, petrological and volcanological data. At present, major online data repositories relevant to studies of degassing are not linked and interoperable. We are developing interoperability between three of those, which will support more powerful synoptic studies of degassing. The three data systems that will make their data accessible via the DECADE portal are: (1) the Smithsonian Institution's Global Volcanism Program database (GVP) of volcanic activity data, (2) EarthChem databases for geochemical and geochronological data of rocks and melt inclusions, and (3) the MaGa database (Mapping Gas emissions) which contains compositional and flux data of gases released at volcanic and non-volcanic degassing sites. These databases are developed and maintained by institutions or groups of experts in a specific field, and data are archived in formats specific to these databases. In the framework of the Deep Earth Carbon Degassing (DECADE) initiative of the Deep Carbon Observatory (DCO), we are developing a web portal that will create a powerful search engine of these databases from a single entry point. The portal will return comprehensive multi-component datasets, based on the search criteria selected by the user. For example, a single geographic or temporal search will return data relating to compositions of emitted gases and erupted products, the age of the erupted products, and coincident activity at the volcano. The development of this level of capability for the DECADE Portal requires complete synergy between these databases, including availability of standard-based web services (WMS, WFS) at all data systems. Data and metadata can thus be extracted from each system without interfering with each database's local schema or being replicated to achieve integration at

  19. Rare earth-doped lead borate glasses and transparent glass-ceramics: structure-property relationship.

    PubMed

    Pisarski, W A; Pisarska, J; Mączka, M; Lisiecki, R; Grobelny, Ł; Goryczka, T; Dominiak-Dzik, G; Ryba-Romanowski, W

    2011-08-15

    Correlation between structure and optical properties of rare earth ions in lead borate glasses and glass-ceramics was evidenced by X-ray-diffraction, Raman, FT-IR and luminescence spectroscopy. The rare earths were limited to Eu(3+) and Er(3+) ions. The observed BO(3)↔BO(4) conversion strongly depends on the relative PbO/B(2)O(3) ratios in glass composition, giving important contribution to the luminescence intensities associated to (5)D(0)-(7)F(2) and (5)D(0)-(7)F(1) transitions of Eu(3+). The near-infrared luminescence and up-conversion spectra for Er(3+) ions in lead borate glasses before and after heat treatment were measured. The more intense and narrowing luminescence lines suggest partial incorporation of Er(3+) ions into the orthorhombic PbF(2) crystalline phase, which was identified using X-ray diffraction analysis. PMID:21093353

  20. Tip enhancement of upconversion photoluminescence from rare earth ion doped nanocrystals.

    PubMed

    Mauser, Nina; Piatkowski, Dawid; Mancabelli, Tobia; Nyk, Marcin; Mackowski, Sebastian; Hartschuh, Achim

    2015-04-28

    We present tip-enhanced upconversion photoluminescence (PL) images of Er(3+)- and Yb(3+)-doped NaYF4 nanocrystals on glass substrates with subdiffraction spatial resolution. Tip-sample distance dependent measurements clearly demonstrate the near-field origin of the image contrast. Time-resolved PL measurements show that the tip increases the spontaneous emission rate of the two emission channels of Er(3+) in the visible region. Very efficient enhancement of upconversion PL is discussed in the context of the two-photon nature of the excitation process and homoenergy transfer between the ions within the nanocrystals. Comparison between different nanocrystals and tips shows a strong influence of the tip shape on the image contrast that becomes particularly relevant for the larger dimensions of the investigated nanocrystals.

  1. Rare-earth-doped biological composites as in vivo shortwave infrared reporters

    PubMed Central

    Naczynski, D.J.; Tan, M.C.; Zevon, M.; Wall, B.; Kohl, J.; Kulesa, A.; Chen, S.; Roth, C.M.; Riman, R.E.; Moghe, P.V.

    2013-01-01

    The extension of in vivo optical imaging for disease screening and image-guided surgical interventions requires brightly-emitting, tissue-specific materials that optically transmit through living tissue and can be imaged with portable systems that display data in real-time. Recent work suggests that a new window across the short wavelength infrared region can improve in vivo imaging sensitivity over near infrared light. Here we report on the first evidence of multispectral, real-time short wavelength infrared imaging offering anatomical resolution using brightly-emitting rare-earth nanomaterials and demonstrate their applicability toward disease-targeted imaging. Inorganic-protein nanocomposites of rare-earth nanomaterials with human serum albumin facilitated systemic biodistribution of the rare-earth nanomaterials resulting in the increased accumulation and retention in tumor tissue that was visualized by the localized enhancement of infrared signal intensity. Our findings lay the groundwork for a new generation of versatile, biomedical nanomaterials that can advance disease monitoring based on a pioneering infrared imaging technique. PMID:23873342

  2. Rare-earth-doped biological composites as in vivo shortwave infrared reporters.

    PubMed

    Naczynski, D J; Tan, M C; Zevon, M; Wall, B; Kohl, J; Kulesa, A; Chen, S; Roth, C M; Riman, R E; Moghe, P V

    2013-01-01

    The extension of in vivo optical imaging for disease screening and image-guided surgical interventions requires brightly emitting, tissue-specific materials that optically transmit through living tissue and can be imaged with portable systems that display data in real-time. Recent work suggests that a new window across the short-wavelength infrared region can improve in vivo imaging sensitivity over near infrared light. Here we report on the first evidence of multispectral, real-time short-wavelength infrared imaging offering anatomical resolution using brightly emitting rare-earth nanomaterials and demonstrate their applicability toward disease-targeted imaging. Inorganic-protein nanocomposites of rare-earth nanomaterials with human serum albumin facilitated systemic biodistribution of the rare-earth nanomaterials resulting in the increased accumulation and retention in tumour tissue that was visualized by the localized enhancement of infrared signal intensity. Our findings lay the groundwork for a new generation of versatile, biomedical nanomaterials that can advance disease monitoring based on a pioneering infrared imaging technique. PMID:23873342

  3. The EPOS Implementation Phase: building thematic and integrated services for solid Earth sciences

    NASA Astrophysics Data System (ADS)

    Cocco, Massimo; Epos Consortium, the

    2015-04-01

    The European Plate Observing System (EPOS) has a scientific vision and approach aimed at creating a pan-European infrastructure for Earth sciences to support a safe and sustainable society. To follow this vision, the EPOS mission is integrating a suite of diverse and advanced Research Infrastructures (RIs) in Europe relying on new e-science opportunities to monitor and understand the dynamic and complex Earth system. To this goal, the EPOS Preparatory Phase has designed a long-term plan to facilitate integrated use of data and products as well as access to facilities from mainly distributed existing and new research infrastructures for solid Earth Science. EPOS will enable innovative multidisciplinary research for a better understanding of the Earth's physical processes that control earthquakes, volcanic eruptions, ground instability and tsunami as well as the processes driving tectonics and Earth surface dynamics. Through integration of data, models and facilities EPOS will allow the Earth Science community to make a step change in developing new concepts and tools for key answers to scientific and socio-economic questions concerning geo-hazards and geo-resources as well as Earth sciences applications to the environment and to human welfare. Since its conception EPOS has been built as "a single, Pan-European, sustainable and distributed infrastructure". EPOS is, indeed, the sole infrastructure for solid Earth Science in ESFRI and its pan-European dimension is demonstrated by the participation of 23 countries in its preparatory phase. EPOS is presently moving into its implementation phase further extending its pan-European dimension. The EPOS Implementation Phase project (EPOS IP) builds on the achievements of the successful EPOS preparatory phase project. The EPOS IP objectives are synergetic and coherent with the establishment of the new legal subject (the EPOS-ERIC in Italy). EPOS coordinates the existing and new solid Earth RIs within Europe and builds the

  4. Evidence of dilute ferromagnetism in rare-earth doped yttrium aluminium garnet

    SciTech Connect

    Farr, Warrick G.; Goryachev, Maxim; Le Floch, Jean-Michel; Tobar, Michael E.; Bushev, Pavel

    2015-09-21

    This work demonstrates strong coupling regime between an erbium ion spin ensemble and microwave hybrid cavity-whispering gallery modes in a yttrium aluminium garnet dielectric crystal. Coupling strengths of 220 MHz and mode quality factors in excess of 10{sup 6} are demonstrated. Moreover, the magnetic response of high-Q modes demonstrates behaviour which is unusual for paramagnetic systems. This behaviour includes hysteresis and memory effects. Such qualitative change of the system's magnetic field response is interpreted as a phase transition of rare earth ion impurities. This phenomenon is similar to the phenomenon of dilute ferromagnetism in semiconductors. The clear temperature dependence of the phenomenon is demonstrated.

  5. A Special Assignment from NASA: Understanding Earth's Atmosphere through the Integration of Science and Mathematics

    ERIC Educational Resources Information Center

    Fox, Justine E.; Glen, Nicole J.

    2012-01-01

    Have your students ever wondered what NASA scientists do? Have they asked you what their science and mathematics lessons have to do with the real world? This unit about Earth's atmosphere can help to answer both of those questions. The unit described here showcases "content specific integration" of science and mathematics in that the lessons meet…

  6. Surface cleaning and etching of rare-earth-doped phosphate glass

    NASA Astrophysics Data System (ADS)

    Barnes, Amy S.; Pantano, Carlo G.; Conzone, Samuel D.

    2001-11-01

    The surface reactions of phosphate glasses are important for the processing and application of photonic devices, biomedical materials and conventional optical components. Of particular concern are the leaching of optically-active dopant species, surface layer formation and roughening during polishing, cleaning and other fabrication processes. In this study, the effects of various cleaning treatments, and both acid and base etching, were evaluated using surface analytical techniques (XPS, AFM). It is shown that in these phosphate glasses, the aluminum and rare-earth oxides have limited aqueous solubility, whereas the phosphate network is soluble over a wider range of pH. Thus, under those conditions where polishing damage can be removed by etching the surface, a localized precipitation of rare-earth oxides occurs which influences the final roughness and surface composition. Conversely, under conditions where this precipitation can be eliminated, an in-depth leaching of the surface occurs. These aqueous surface reactions were similar for both the optically-active and passive IOG-1 glasses. An optimized surface preparation method is described.

  7. Luminescence properties of rare earth doped metal oxide nanostructures: A case of Eu-ZnO

    NASA Astrophysics Data System (ADS)

    Sahu, D.; Acharya, B. S.; Panda, N. R.

    2016-05-01

    The present study reports the growth and luminescence properties of Eu doped ZnO nanostructures. The experiment has been carried out by synthesizing the materials by simple wet-chemical method. X-ray diffraction (XRD) studies show expansion of ZnO lattice with the incorporation of Eu ions which has been confirmed from the appearance of Eu2O3 as a minor phase in the XRD pattern. The estimation of crystallite size from XRD results matches closely with the results obtained from transmission electron microscopy. Further, these results show the formation of nanosized Eu-ZnO particles of average size around 60 nm stacked on each other. FTIR studies show the presence of both Zn-O and Eu-O modes in the spectra supporting the results obtained from XRD. The interesting results obtained from photoluminescence (PL) measurements show the presence of both band edge emission in UV region and the defect emissions in violet, blue and green region. The appearance of 5D0→7FJ transitions of Eu3+ ions in red region clearly suggests the possible occurrence of energy transfer between the energy states of ZnO host and Eu3+ ions.

  8. Luminescence properties of solid solutions of borates doped with rare-earth ions

    NASA Astrophysics Data System (ADS)

    Levushkina, V. S.; Mikhailin, V. V.; Spassky, D. A.; Zadneprovski, B. I.; Tret'yakova, M. S.

    2014-11-01

    The structural and luminescence properties of LuxY1 - xBO3 solid solutions doped with Ce3+ or Eu+3 have been investigated. It has been found that the solid solutions crystallize in the vaterite phase with a lutetium concentration x < 0.5. For a higher lutetium concentration x, the solid solutions contain an additional calcite phase with a content less than 5 wt %. The luminescence spectra are characterized by intensive impurity emission under excitation with the synchrotron radiation in the X-ray and ultraviolet spectral ranges. It has been shown that, as the lutetium concentration x in the LuxY1 - xBO3: Ce3+ solid solutions increases, the emission intensity smoothly decreases, which is associated with a gradual shift of the Ce3+ 5 d(1) level toward the bottom of the conduction band, as well as with a decrease in the band gap. It has been established that, in the LuxY1 - xBO3: Eu3+ solid solutions with intermediate concentrations x, the efficiency of energy transfer to luminescence centers increases. This effect is explained by the limited spatial separation of electrons and holes in the solid solutions. It has been demonstrated that the calcite phase adversely affects the luminescence properties of the solid solutions.

  9. Theoretical investigation of the structures, stabilities, and NLO responses of calcium-doped pyridazine: alkaline-earth-based alkaline salt electrides.

    PubMed

    Wang, Yin-Feng; Huang, Jiangen; Jia, Li; Zhou, Guangpei

    2014-02-01

    Currently, whether alkaline-earth-doped compounds with electride characteristics are novel candidates for high-performance nonlinear optical (NLO) materials is unknown. In this paper, using quantum chemical computations, we show that: when doping calcium atoms into a family of alkaline-substituted pyridazines, alkaline-earth-based alkaline salt electrides M-H₃C₄N₂⋯Ca (M=H, Li, and K) with distended excess electron clouds are formed. Interestingly, from the triplet to the singlet state, the chemical valence of calcium atom changes from +1 to 0, and the dipole moment direction (μ₀) of the molecule reverses for each M-H₃C₄N₂⋯Ca. Changing pyridazine from without (H₄C₄N₂⋯Ca) to with one alkaline substituent (M-H₃C₄N₂⋯Ca, M=Li and K), the ground state changes from the triplet to the singlet state. The alkaline earth metal doping effect (electride effect) and alkaline salt effect on the static first hyperpolarizabilities (β₀) demonstrates that (1) the β₀ value is increased approximately 1371-fold from 2 (pyridazine, H₄C₄N₂) to 2745au (Ca-doped pyridazine, H₄C₄N₂⋯Ca), (2) the β₀ value is increased approximately 1146-fold from 2 in pyridazine (H₄C₄N₂) to 2294au in an Li-substituted pyridazine (Li-H₃C₄N₂), and (3) the β₀ value is increased 324-(M=Li) and 106-(M=K) fold from 826 (MLi) and 2294au (MK) to 268,679 (M=Li) and 245,878au (M=K), respectively, from the alkalized pyridazine (M-H₃C₄N₂) to the Ca-doped pyridazine (M-H₃C₄N₂⋯Ca). These results may provide a new means for designing high-performance NLO materials.

  10. Luminescent rare earth vanadate nanoparticles doped with Eu3+ and Bi3 for sensing and imaging applications

    NASA Astrophysics Data System (ADS)

    Escudero, Alberto; Carrillo-Carrión, Carolina; Zyuzin, Mikhail; Hartmann, Raimo; Ashraf, Sumaira; Parak, Wolfgang J.

    2016-03-01

    Nanoparticles (NPs) are attracting interest in nanomedicine due to their potential medical applications, ranging from optical biolabels and contrast agents for magnetic resonance imaging to carriers for drug and gene delivery for disease therapy.[1] Rare earth (RE) based nanophosphors exhibit important advantages compared with other available luminescent materials, such as quantum dots and nanostructures functionalized with organic dyes, due to their lower toxicities, photostabilities, high thermal and chemical stabilities, high luminescence quantum yields, and sharp emission bands.[2] Yttrium orthovanadate NPs doped with Eu3+ and Bi3+, functionalized with poly acryl acid (PAA), and excitable by near-ultraviolet light have been synthesized by homogeneous precipitation at 120 °C from solutions of rare earth precursors (yttrium acetylacetonate and europium nitrate), bismuth nitrate, sodium orthovanadate, and PAA, in an ethylene glycol/water mixture. Quasispheres with sizes from 93 to 51 nm were obtained. The as synthesized NPs were already functionalized with PAA. The NPs showed the typical red luminescence of Eu3+, which can be excited with near-UV light through an energy transfer from the vanadate anion. The presence of Bi3+ shifts the maximum of the broad excitation band from 280 nm to 342 nm. This excitation path is much more efficient than the direct excitation of the Eu3+ electronic levels, and results in a much higher luminescence. The NPs can be uptaken by HeLa cells, and are eventually located in the lysosomes after being internalized. Finally, the functionalization with PAA provides -COOH anchors for adding functional ligands of biomedical interest that can be used for sensing applications.

  11. Fluorescence in nanocomposites based on polyethylene oxides and block copolymers of polyethylene oxide-polypropylene oxide loaded with rare earth doped fluorides

    NASA Astrophysics Data System (ADS)

    Yust, Brian; Pedraza, Francisco; Sardar, Dhiraj; Saenz, Aaron; Chipara, Mircea

    2015-03-01

    Rare earth doped fluoride nanoparticles with a size of about 25 nm have been synthesized by a solvothermal process. Polymer-based nanocomposites, containing various weight fraction of nanofillers, have been obtained by dissolving the polymeric matrix (polyethylene oxide) within a solvent (deionized water), adding the nanoparticles, sonicating the mixture, and finally removing the solvent. The complete removal of the solvent has been confirmed by Thermogravimetric Analysis. Additional information about the thermal features have been obtained by Differential Scanning Calorimetry, Wide Angle X-Ray Scattering, FTIR, UV-Visible, and Raman. The effect of the loading with nanoparticles on the glass, crystallization, and melting transition temperatures of the polymeric matrix are reported. Fluorescence of rare earth doped nanoparticles dispersed within the polymeric matrix has been tested by laser spectroscopy. The dependence of fluorescence intensity on the concentration of nanofillers and on temperature in the range 300 to 400 K is analyzed.

  12. Multiple doping structures of the rare-earth atoms in β-SiAlON:Ce phosphors and their effects on luminescence properties.

    PubMed

    Gan, Lin; Xu, Fang-Fang; Zeng, Xiong-Hui; Li, Zuo-Sheng; Mao, Zhi-Yong; Lu, Ping; Zhu, Ying-Chun; Liu, Xue-Jian; Zhang, Lin-Lin

    2015-07-14

    The critical doping structures of rare-earth atoms in the promising β-SiAlON phosphors have long been argued owing to the lack of direct evidence. Here, the exact locations and coordination of the Ce rare-earth atoms in the β-SiAlON structure have been examined using an atom-resolved Cs-corrected scanning transmission electron microscope. Three different occupation sites for the Ce atoms have been directly observed: two of them are in the structural channel coordinated with six and nine N(O) atoms, respectively; the other one is the unexpected substitution site for Si(Al). The chemical valences and stabilities of the doping Ce ions at the different occupation sites have been evaluated using density functional calculations. Correlation of the different doping structures with the luminescence properties has been investigated by the aid of cathodoluminescence (CL) microanalysis, which verifies the different contribution of the interstitial trivalent Ce ions to the light emission while no luminescence is observed for the substitutional doping of quadrivalent Ce.

  13. Storage and retrieval of collective excitations on a long-lived spin transition in a rare-earth ion-doped crystal.

    PubMed

    Goldschmidt, E A; Beavan, S E; Polyakov, S V; Migdall, A L; Sellars, M J

    2013-04-22

    Robust, long-lived optical quantum memories are important components of many quantum information and communication protocols. We demonstrate coherent generation, storage, and retrieval of excitations on a long-lived spin transition via spontaneous Raman scattering in a rare-earth ion-doped crystal. We further study the time dynamics of the optical correlations in this system. This is the first demonstration of its kind in a solid and an enabling step toward realizing a solid-state quantum repeater.

  14. Photodarkening study of gratings written into rare-earth doped optical fibres using a femtosecond laser

    NASA Astrophysics Data System (ADS)

    Åslund, Mattias L.; Jovanovic, Nemanja; Groothoff, Nathaniel; Canning, John; Marshall, Graham D.; Jackson, Stuart D.; Fuerbach, Alex; Withford, Michael J.

    2007-12-01

    A well-known side-effect from fibre Bragg grating UV-fabrication is short wavelength attenuation, where irradiation with laser light, usually in the UV, generates both defect-induced absorption and scattering. These losses are especially problematic for high power optical fibre lasers operating at shorter wavelengths where resonant assisted coupling into the glass matrix through the rare earth ions can take place (e.g. Yb 3+). In this, work we present a study of the relative magnitude of short wavelength attenuation in gratings written by the point-by-point method using a Ti-sapphire femtosecond laser operating at 800 nm. Such gratings are very stable and have been used as the feedback elements in fibre lasers with powers exceeding 100 W. We show that the scattering properties responsible for the attenuation are analogous to those associated with type II gratings written with UV lasers.

  15. Earth System Chemistry integrated Modelling (ESCiMo) with the Modular Earth Submodel System (MESSy) version 2.51

    NASA Astrophysics Data System (ADS)

    Jöckel, Patrick; Tost, Holger; Pozzer, Andrea; Kunze, Markus; Kirner, Oliver; Brenninkmeijer, Carl A. M.; Brinkop, Sabine; Cai, Duy S.; Dyroff, Christoph; Eckstein, Johannes; Frank, Franziska; Garny, Hella; Gottschaldt, Klaus-Dirk; Graf, Phoebe; Grewe, Volker; Kerkweg, Astrid; Kern, Bastian; Matthes, Sigrun; Mertens, Mariano; Meul, Stefanie; Neumaier, Marco; Nützel, Matthias; Oberländer-Hayn, Sophie; Ruhnke, Roland; Runde, Theresa; Sander, Rolf; Scharffe, Dieter; Zahn, Andreas

    2016-03-01

    Three types of reference simulations, as recommended by the Chemistry-Climate Model Initiative (CCMI), have been performed with version 2.51 of the European Centre for Medium-Range Weather Forecasts - Hamburg (ECHAM)/Modular Earth Submodel System (MESSy) Atmospheric Chemistry (EMAC) model: hindcast simulations (1950-2011), hindcast simulations with specified dynamics (1979-2013), i.e. nudged towards ERA-Interim reanalysis data, and combined hindcast and projection simulations (1950-2100). The manuscript summarizes the updates of the model system and details the different model set-ups used, including the on-line calculated diagnostics. Simulations have been performed with two different nudging set-ups, with and without interactive tropospheric aerosol, and with and without a coupled ocean model. Two different vertical resolutions have been applied. The on-line calculated sources and sinks of reactive species are quantified and a first evaluation of the simulation results from a global perspective is provided as a quality check of the data. The focus is on the intercomparison of the different model set-ups. The simulation data will become publicly available via CCMI and the Climate and Environmental Retrieval and Archive (CERA) database of the German Climate Computing Centre (DKRZ). This manuscript is intended to serve as an extensive reference for further analyses of the Earth System Chemistry integrated Modelling (ESCiMo) simulations.

  16. Optical detection of ultrasound using AFC-based quantum memory technique in cryogenic rare earth ion doped crystals

    NASA Astrophysics Data System (ADS)

    Taylor, Luke R.; McAuslan, David L.; Longdell, Jevon J.

    2013-03-01

    We present results of a novel and highly sensitive technique for the optical detection of ultrasound using the selective storage of frequency shifted photons in an inherently highly efficient and low noise atomic frequency comb (AFC) based quantum memory. The ultrasound `tagged' optical sidebands are absorbed within a pair of symmetric AFCs, generated via optical pumping in a Pr3+:Y2SiO5 sample (tooth separation Δ = 150 kHz, comb finesse fc ~ 2 and optical depth αL ~ 2), separated by twice the ultrasound modulation frequency (1.5 MHz) and centered on either side of a broad spectral pit (1.7 MHz width) allowing transmission of the carrier. The stored sidebands are recovered with 10-20% efficiency as a photon echo (as defined by the comb parameters), and we demonstrate a record 49 dB discrimination between the sidebands and the carrier pulse, high discrimination being important for imaging tissues at depth. We further demonstrate detector limited discrimination (~29 dB) using a highly scattered beam, confirming that the technique is immune to speckle decorrelation. We show that it also remains valid in the case of optically thin samples, and thus represents a significant improvement over other ultrasound detection methods based on rare-earth-ion-doped crystals. These results strongly suggest the suitability of our technique for high-resolution non-contact real-time imaging of biological tissues.

  17. High pressure effects on the superconductivity in rare-earth-doped CaFe2As2

    NASA Astrophysics Data System (ADS)

    Uhoya, Walter; Cargill, Daniel; Gofryk, Krzysztof; Tsoi, Georgiy M.; Vohra, Yogesh K.; Sefat, Athena S.; Weir, S. T.

    2014-01-01

    High pressure superconductivity in a rare-earth-doped Ca0.86Pr0.14Fe2As2 single-crystalline sample has been studied up to 12 GPa and temperatures down to 11 K using the designer diamond anvil cell under a quasi-hydrostatic pressure medium. The electrical resistance measurements were complemented by high pressure and low-temperature X-ray diffraction studies at a synchrotron source. The electrical resistance measurements show an intriguing observation of superconductivity under pressure, with Tc as high as ∼51 K at 1.9 GPa, presenting the highest Tc reported in the intermetallic class of 122 iron-based superconductors. The resistive transition observed suggests a possible existence of two superconducting phases at low pressures of 0.5 GPa: one phase starting at Tc1 ∼ 48 K and the other starts at Tc2 ∼ 16 K. The two superconducting transitions show distinct variations with increasing pressure. High pressure and low-temperature structural studies indicate that the superconducting phase is a collapsed tetragonal ThCr2Si2-type (122) crystal structure.

  18. Energy transfer kinetics in oxy-fluoride glass and glass-ceramics doped with rare-earth ions

    SciTech Connect

    Sontakke, Atul D.; Annapurna, K.

    2012-07-01

    An investigation of donor-acceptor energy transfer kinetics in dual rare earths doped precursor oxy-fluoride glass and its glass-ceramics containing NaYF{sub 4} nano-crystals is reported here, using three different donor-acceptor ion combinations such as Nd-Yb, Yb-Dy, and Nd-Dy. The precipitation of NaYF{sub 4} nano-crystals in host glass matrix under controlled post heat treatment of precursor oxy-fluoride glasses has been confirmed from XRD, FESEM, and transmission electron microscope (TEM) analysis. Further, the incorporation of dopant ions inside fluoride nano-crystals has been established through optical absorption and TEM-EDX analysis. The noticed decreasing trend in donor to acceptor energy transfer efficiency from precursor glass to glass-ceramics in all three combinations have been explained based on the structural rearrangements that occurred during the heat treatment process. The reduced coupling phonon energy for the dopant ions due to fluoride environment and its influence on the overall phonon assisted contribution in energy transfer process has been illustrated. Additionally, realization of a correlated distribution of dopant ions causing clustering inside nano-crystals has also been reported.

  19. Determination of Judd-Ofelt intensity parameters from the excitation spectra for rare-earth doped luminescent materials.

    PubMed

    Luo, Wenqin; Liao, Jinsheng; Li, Renfu; Chen, Xueyuan

    2010-04-01

    By utilizing the proportional relationship between the excitation and absorption spectra for some special excited multiplets of rare-earth (RE) ions that are followed by a very fast nonradiative relaxation to the monitored level, we propose a new approach to determine the Judd-Ofelt (JO) intensity parameters that are crucial to the evaluation of laser and luminescent materials via excitation spectra. To validate this approach, the JO parameters of NaGd(WO(4))(2) : Er(3+) and YLiF(4) : Nd(3+) crystals are calculated and compared through both the excitation and absorption spectra. The JO parameters derived from this approach are in good agreement with that determined from the conventional method (absorption spectra). Furthermore, the JO intensity parameters of Y(2)O(3) : Er(3+) nanocrystals are derived from the excitation spectra by taking into account the nano-size effects, which are comparable to the values of the crystal counterpart. The proposed approach is of particular importance for those powders or nanophosphors with low RE doping concentration that their quantitative absorption spectra are difficult to measure.

  20. Engineering rare-earth-doped heavy metal oxide glasses for 2-5 μm lasers

    NASA Astrophysics Data System (ADS)

    Richards, Billy D. O.; Jha, Animesh; Dorofeev, Vitaly; Manzur, Tariq

    2010-04-01

    The electronic states in trivalent rare-earth ions offer an excellent opportunity for designing efficient fibre and bulk lasers for atmospheric remote sensing and LIDAR technology. The first part of this review article focuses on engineering passive fibres for 2-5 μm transmission. The fabrication of single-mode tungsten tellurite optical fibres from high purity bulk glass rods is described. Fibres with a numerical aperture of 0.1 and core diameter of 10+/-2 μm have been drawn using suction and rod-in-tube techniques of fibre preform fabrication. Losses of 2.3 dBm-1 at 974 nm have been measured. These fibres are of interest for use as passive transmission fibre or active fibres for lasing in the 2-5 μm spectral region. The use of heavy metal oxides in the fabrication of glass leads to extended infrared transmission. In the 2nd part of the review we compare the slope efficiencies of Tm3+ and Tm3+/Ho3+ doped glasses and fibres for 1950-2080 nm lasers using a range of pumping schemes in tellurite and germanium oxide hosts. We also explain the importance of choosing 1950-2080 nm tunable lasers as a pump source for stimulated emission at longer wavelengths.

  1. Magnetocaloric effect in heavy rare-earth elements doped Fe-based bulk metallic glasses with tunable Curie temperature

    SciTech Connect

    Li, Jiawei; Huo, Juntao; Chang, Chuntao E-mail: dujun@nimte.ac.cn; Du, Juan E-mail: dujun@nimte.ac.cn; Man, Qikui; Wang, Xinmin; Li, Run-Wei; Law, Jiayan

    2014-08-14

    The effects of heavy rare earth (RE) additions on the Curie temperature (T{sub C}) and magnetocaloric effect of the Fe-RE-B-Nb (RE = Gd, Dy and Ho) bulk metallic glasses were studied. The type of dopping RE element and its concentration can easily tune T{sub C} in a large temperature range of 120 K without significantly decreasing the magnetic entropy change (ΔS{sub M}) and refrigerant capacity (RC) of the alloys. The observed values of ΔS{sub M} and RC of these alloys compare favorably with those of recently reported Fe-based metallic glasses with enhanced RC compared to Gd{sub 5}Ge{sub 1.9}Si{sub 2}Fe{sub 0.1}. The tunable T{sub C} and large glass-forming ability of these RE doped Fe-based bulk metallic glasses can be used in a wide temperature range with the final required shapes.

  2. Synthesis and upconversion emission of rare earth-doped olive-like YF{sub 3} micro-particles

    SciTech Connect

    Lin, Hang; Chen, Daqin; Niu, Mutong; Yu, Yunlong; Huang, Ping; Wang, Yuansheng

    2010-01-15

    The olive-like YF{sub 3} micro-particles were fabricated via a two-step route. The precursor NH{sub 4}Y{sub 3}F{sub 10} nano-cages sized 8 nm with hollow interiors were first synthesized in a solid reaction at room temperature. In the course of subsequent hydrothermal treating, the unstable NH{sub 4}Y{sub 3}F{sub 10} nano-cages were decomposed, resulted in the formation of Y(OH){sub 1.63}F{sub 1.37} micro-tubes. Prolonging the hydrothermal reaction induced the further decomposition of Y(OH){sub 1.63}F{sub 1.37} to produce YF{sub 3} nano-crystals, which then aggregated together forming the final olive-like YF{sub 3} micro-particles. For the Er{sup 3+}/Yb{sup 3+} co-doped olive-like YF{sub 3} micro-particles, intense visible upconversion emissions were measured under 976 nm excitation owing to the partition of rare earth ions in the lattice, indicating this material a promising luminescent host.

  3. Ethyl Acetate Abatement on Copper Catalysts Supported on Ceria Doped with Rare Earth Oxides.

    PubMed

    Carabineiro, Sónia Alexandra Correia; Konsolakis, Michalis; Marnellos, George Emmanouil-Nontas; Asad, Muhammad Faizan; Soares, Olívia Salomé Gonçalves Pinto; Tavares, Pedro Bandeira; Pereira, Manuel Fernando Ribeiro; Órfão, José Joaquim de Melo; Figueiredo, José Luís

    2016-01-01

    Different lanthanide (Ln)-doped cerium oxides (Ce0.5Ln0.5O1.75, where Ln: Gd, La, Pr, Nd, Sm) were loaded with Cu (20 wt. %) and used as catalysts for the oxidation of ethyl acetate (EtOAc), a common volatile organic compound (VOC). For comparison, both Cu-free (Ce-Ln) and supported Cu (Cu/Ce-Ln) samples were characterized by N₂ adsorption at -196 °C, scanning/transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and temperature programmed reduction in H₂. The following activity sequence, in terms of EtOAc conversion, was found for bare supports: CeO₂ ≈ Ce0.5Pr0.5O1.75 > Ce0.5Sm0.5O1.75 > Ce0.5Gd0.5O1.75 > Ce0.5Nd0.5O1.75 > Ce0.5La0.5O1.75. Cu addition improved the catalytic performance, without affecting the activity order. The best catalytic performance was obtained for Cu/CeO₂ and Cu/Ce0.5Pr0.5O1.75 samples, both achieving complete EtOAc conversion below ca. 290 °C. A strong correlation was revealed between the catalytic performance and the redox properties of the samples, in terms of reducibility and lattice oxygen availability. Νo particular correlation between the VOC oxidation performance and textural characteristics was found. The obtained results can be explained in terms of a Mars-van Krevelen type redox mechanism involving the participation of weakly bound (easily reduced) lattice oxygen and its consequent replenishment by gas phase oxygen.

  4. Ethyl Acetate Abatement on Copper Catalysts Supported on Ceria Doped with Rare Earth Oxides.

    PubMed

    Carabineiro, Sónia Alexandra Correia; Konsolakis, Michalis; Marnellos, George Emmanouil-Nontas; Asad, Muhammad Faizan; Soares, Olívia Salomé Gonçalves Pinto; Tavares, Pedro Bandeira; Pereira, Manuel Fernando Ribeiro; Órfão, José Joaquim de Melo; Figueiredo, José Luís

    2016-01-01

    Different lanthanide (Ln)-doped cerium oxides (Ce0.5Ln0.5O1.75, where Ln: Gd, La, Pr, Nd, Sm) were loaded with Cu (20 wt. %) and used as catalysts for the oxidation of ethyl acetate (EtOAc), a common volatile organic compound (VOC). For comparison, both Cu-free (Ce-Ln) and supported Cu (Cu/Ce-Ln) samples were characterized by N₂ adsorption at -196 °C, scanning/transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and temperature programmed reduction in H₂. The following activity sequence, in terms of EtOAc conversion, was found for bare supports: CeO₂ ≈ Ce0.5Pr0.5O1.75 > Ce0.5Sm0.5O1.75 > Ce0.5Gd0.5O1.75 > Ce0.5Nd0.5O1.75 > Ce0.5La0.5O1.75. Cu addition improved the catalytic performance, without affecting the activity order. The best catalytic performance was obtained for Cu/CeO₂ and Cu/Ce0.5Pr0.5O1.75 samples, both achieving complete EtOAc conversion below ca. 290 °C. A strong correlation was revealed between the catalytic performance and the redox properties of the samples, in terms of reducibility and lattice oxygen availability. Νo particular correlation between the VOC oxidation performance and textural characteristics was found. The obtained results can be explained in terms of a Mars-van Krevelen type redox mechanism involving the participation of weakly bound (easily reduced) lattice oxygen and its consequent replenishment by gas phase oxygen. PMID:27196886

  5. Control of the visible emission in the SrZrO3 nano-crystals with the rare earth ion doping.

    PubMed

    Kim, Dong Hwan; Kim, Ji Hyun; Chung, Jin Seok; Lee, Yunsang

    2013-11-01

    We investigated the emission property of SrZrO3 nano-crystals (NCs) with the doping of rare earth (RE) ions, Eu3+ and Tm3+, by using 325 nm photo-excitation. SrZrO3 NCs show a sizable violet-blue emission, while the Eu3+ and Tm3+ ions are well known to be good red and blue phosphors, respectively. Combined emissions of the host and the RE ion dopant might suggest a new white luminescent source. The RE ion doped SrZrO3 NCs were initially synthesized by using the combustion method, and then the as-synthesized crystals were annealed at different temperatures from 650 degrees C to 1450 degrees C. The Eu3+-doped SrZrO3 NCs showed the sharp red emission near 600 nm, in addition to a violet-blue emission of the host material in itself. While the red emission is enhanced in the high temperature post-annealing, the blue emission is suppressed in an opposite way. This close relation between the emissions of the host and dopant was observed similarly in the Tm3+-doped NCs. We could control the emission property in the SrZrO3:Eu3+/Tm3+ NCs from blue to red by thermal annealing and RE ion doping.

  6. MT+, integrating magnetotellurics to determine earth structure, physical state, and processes

    USGS Publications Warehouse

    Bedrosian, P.A.

    2007-01-01

    As one of the few deep-earth imaging techniques, magnetotellurics provides information on both the structure and physical state of the crust and upper mantle. Magnetotellurics is sensitive to electrical conductivity, which varies within the earth by many orders of magnitude and is modified by a range of earth processes. As with all geophysical techniques, magnetotellurics has a non-unique inverse problem and has limitations in resolution and sensitivity. As such, an integrated approach, either via the joint interpretation of independent geophysical models, or through the simultaneous inversion of independent data sets is valuable, and at times essential to an accurate interpretation. Magnetotelluric data and models are increasingly integrated with geological, geophysical and geochemical information. This review considers recent studies that illustrate the ways in which such information is combined, from qualitative comparisons to statistical correlation studies to multi-property inversions. Also emphasized are the range of problems addressed by these integrated approaches, and their value in elucidating earth structure, physical state, and processes. ?? Springer Science+Business Media B.V. 2007.

  7. Lanthanide Contraction Effect In Magnetic Thermoelectric Materials Of Rare Earth-doped Bi1.5Pb0.5Ca2Co2O8

    NASA Astrophysics Data System (ADS)

    Sutjahja, Inge Magdalena; Akbar, Taufik; Nugroho, Agung

    2010-12-01

    We report in this paper the result of synthesis and crystal structure characterization of magnetic thermoelectric materials of rare-earth-doped Bi1.5Pb0.5Ca2Co2O8, namely Bi1.5Pb0.5Ca1.9RE0.1Co2O8 (RE = La, Pr, Sm, Eu, Gd, Ho). Single phase samples have been prepared by solid state reaction process using precursors of Bi2O3, PbO, CaCO3, RE2O3, and Co3O4. The precursors were pulverized, calcinated, and sintered in air at various temperatures for several hours. Analysis of XRD data shows that Bi1.5Pb0.5Ca1.9RE0.1Co2O8 compound is a layered system consisting of an alternate stack of CoO2 layer and Bi2Sr2O4 block along the c-axis. The misfit structure along b-direction is revealed from the difference of the b-axis length belonging to two sublattices, namely hexagonal CdI2-type CoO2 layer and rock-salt (RS) NaCl-type Bi2Sr2O4 block, while they possess the common a- and c-axis lattice parameters and β angles. The overall crystal structure parameters (a, b, and c) increases with type of doping from La to Ho, namely by decreasing the ionic radii of rare-earth ion. We discuss this phenomenon in terms of the lanthanide contraction, an effect commonly found in the rare-earth compound, results from poor shielding of nuclear charge by 4f electrons. In addition, the values of b-lattice parameters in these rare-earth doped samples are almost the same with those belongs to undoped parent compound (Bi1.5Pb0.5Sr2Co2O8) and its related Y-doped (Bi1.5Pb0.5Ca1.9Y0.1Co2O8) samples, while the c-values reduced significantly in rare-earth doped samples, with opposite trend with those of variation of a-axis length. Morevover, the misfit degree in rare-earth doped compound is higher in compared to parent compound and Y-doped samples. We argue that these structural changes induced by rare-earth doping may provide information for the variation of electronic structure of Co-ions (Co3+ and Co4+), in particular their different spin states of low-spin, intermediate-spin, and high-spin. This, in

  8. Observation and integrated Earth-system science: A roadmap for 2016-2025

    NASA Astrophysics Data System (ADS)

    Simmons, Adrian; Fellous, Jean-Louis; Ramaswamy, Venkatachalam; Trenberth, Kevin; Asrar, Ghassem; Balmaseda, Magdalena; Burrows, John P.; Ciais, Philippe; Drinkwater, Mark; Friedlingstein, Pierre; Gobron, Nadine; Guilyardi, Eric; Halpern, David; Heimann, Martin; Johannessen, Johnny; Levelt, Pieternel F.; Lopez-Baeza, Ernesto; Penner, Joyce; Scholes, Robert; Shepherd, Ted

    2016-05-01

    This report is the response to a request by the Committee on Space Research of the International Council for Science to prepare a roadmap on observation and integrated Earth-system science for the coming ten years. Its focus is on the combined use of observations and modelling to address the functioning, predictability and projected evolution of interacting components of the Earth system on timescales out to a century or so. It discusses how observations support integrated Earth-system science and its applications, and identifies planned enhancements to the contributing observing systems and other requirements for observations and their processing. All types of observation are considered, but emphasis is placed on those made from space. The origins and development of the integrated view of the Earth system are outlined, noting the interactions between the main components that lead to requirements for integrated science and modelling, and for the observations that guide and support them. What constitutes an Earth-system model is discussed. Summaries are given of key cycles within the Earth system. The nature of Earth observation and the arrangements for international coordination essential for effective operation of global observing systems are introduced. Instances are given of present types of observation, what is already on the roadmap for 2016-2025 and some of the issues to be faced. Observations that are organised on a systematic basis and observations that are made for process understanding and model development, or other research or demonstration purposes, are covered. Specific accounts are given for many of the variables of the Earth system. The current status and prospects for Earth-system modelling are summarized. The evolution towards applying Earth-system models for environmental monitoring and prediction as well as for climate simulation and projection is outlined. General aspects of the improvement of models, whether through refining the

  9. Synthesis and characterization of rare earth doped barium fluoride nanoparticles and derivatized copper phthalocyanine nanoparticles

    NASA Astrophysics Data System (ADS)

    Bender, Christopher Mark

    1998-12-01

    Nanoparticles of neodymium doped barium fluoride (Nd:BaFsb2) were synthesized for use as the inorganic component of an optical amplifier composite. Microemulsions were used to maintain domain size in the nano-regime (˜100 nm), and decreasing the volume fraction of the aqueous content, while simultaneously increasing the volume fraction of the cosurfactant (methanol), gave a linear relationship between decreasing domain size and increasing volume fraction of alcohol. As Nd was added to the BaFsb2 host, direct incorporation was observed at low dopant levels (0-10 mol-%), a two-phase mixture was observed at intermediate dopant levels (10-50 mol-%), and a nearly amorphous product resulted with very high Nd-dopant levels (>50 mol-%). Fluorescence measurements of the solids showed that concentration quenching was delayed until unusually high levels, probably as a result of the lost crystallinity. Praseodymium and ytterbium codoped barium fluoride (Pr,Yb:BaFsb2) were also synthesized in microemulsions. Though as-prepared powders did not fluoresce, treatment with high temperatures (900sp°C) and dynamic vacuum resulted in products which would fluoresce at 1.3 mum. Lower temperature treatments (500-750sp°C) were used to decrease sintering, however this resulted in Ybsp{3+} products in which Ybsp{3+} fluorescence was quenched by exposure to air. Contamination due to water and hydroxide is believed to be the reason. Ethanolic microemulsions were used to make copper phthalocyanine (CuPc), which was modified with either zinc phthalocyanine (ZnPc) or copper phthalcyaninesulfonic acid by means of a flow system. The sulfonic acid derivative was lost upon aqueous washing. The zinc derivatized product gave a dispersion in n-hexylamine, which was stable for seven days. The mole ratio of Cu:Zn was 1:1 for the solids dispersed in n-hexylamine, and was 6:1 for the solids that were not dispersed. Because underivatized CuPc formed by the same method did not result in a dispersed product

  10. A path-integral Langevin equation treatment of low-temperature doped helium clusters

    NASA Astrophysics Data System (ADS)

    Ing, Christopher; Hinsen, Konrad; Yang, Jing; Zeng, Toby; Li, Hui; Roy, Pierre-Nicholas

    2012-06-01

    We present an implementation of path integral molecular dynamics for sampling low temperature properties of doped helium clusters using Langevin dynamics. The robustness of the path integral Langevin equation and white-noise Langevin equation [M. Ceriotti, M. Parrinello, T. E. Markland, and D. E. Manolopoulos, J. Chem. Phys. 133, 124104 (2010)], 10.1063/1.3489925 sampling methods are considered for those weakly bound systems with comparison to path integral Monte Carlo (PIMC) in terms of efficiency and accuracy. Using these techniques, convergence studies are performed to confirm the systematic error reduction introduced by increasing the number of discretization steps of the path integral. We comment on the structural and energetic evolution of HeN-CO2 clusters from N = 1 to 20. To quantify the importance of both rotations and exchange in our simulations, we present a chemical potential and calculated band origin shifts as a function of cluster size utilizing PIMC sampling that includes these effects. This work also serves to showcase the implementation of path integral simulation techniques within the molecular modelling toolkit [K. Hinsen, J. Comp. Chem. 21, 79 (2000)], 10.1002/(SICI)1096-987X(20000130)21:2<79::AID-JCC1>3.0.CO;2-B, an open-source molecular simulation package.

  11. Using the Earth as an Effective Model for Integrating Space Science Into Education Outreach Programs

    NASA Astrophysics Data System (ADS)

    Morris, P. A.; Allen, J.; Galindo, C.; McKay, G.; Obot, V.; Reiff, P.

    2005-05-01

    Our methods of teaching Earth and space science as two disciplines do not represent the spirit of earlier scientists such as Aristotle, da Vinci, and Galileo. We need to re-evaluate these methods and take advantage of the excitement created in the general public over the recent space science exploration programs. The information that we are obtaining from both the Mars missions and Cassini-Huygens focuses on interpreting geomorphology, mineral compositions and gas identification based on Earth as a baseline for data evaluation. This type of evaluation is an extension of Hutton's 18th century principle of Uniformitarianism, the present is the key to the past, or Earth is the key for understanding extraterrestrial bodies. Geomorphological examples are volcanic activity, meteoritic impacts, and evidence of water altering surface features. The Hawaiian, or shield, type volcanoes are analogues for Olympus Mons and the other volcanoes on Mars. Other examples include comparing sand dunes on Earth with possible Martian dunes, known stream patterns on Earth with potential stream patterns on Mars, and even comparing meteoritic impact features on Mars, the Earth, Moon and Mercury. All of these comparisons have been developed into inquiry-based activities and are available through NASA publications. Each of these activities is easily adapted to emphasize either Earth science or space science or both. Beyond geomorphology, solar storms are an excellent topic for integrating Earth and space science. Solar storms are traditionally part of space science studies, but most students do not understand their effect on Earth or the intense effects they could have on humans, whether traveling through space or exploring the surfaces of the Moon or Mars. Effects are not only limited to space travel and other planetary surfaces but also include Earth's magnetosphere, which in turn, affect radio transmission and potentially climate. Like geomorphology courses, there are extensive NASA

  12. The European Plate Observing System (EPOS): Integrating Thematic Services for Solid Earth Science

    NASA Astrophysics Data System (ADS)

    Atakan, Kuvvet; Bailo, Daniele; Consortium, Epos

    2016-04-01

    The mission of EPOS is to monitor and understand the dynamic and complex Earth system by relying on new e-science opportunities and integrating diverse and advanced Research Infrastructures in Europe for solid Earth Science. EPOS will enable innovative multidisciplinary research for a better understanding of the Earth's physical and chemical processes that control earthquakes, volcanic eruptions, ground instability and tsunami as well as the processes driving tectonics and Earth's surface dynamics. Through integration of data, models and facilities EPOS will allow the Earth Science community to make a step change in developing new concepts and tools for key answers to scientific and socio-economic questions concerning geo-hazards and geo-resources as well as Earth sciences applications to the environment and to human welfare. EPOS, during its Implementation Phase (EPOS-IP), will integrate multidisciplinary data into a single e-infrastructure. Multidisciplinary data are organized and governed by the Thematic Core Services (TCS) and are driven by various scientific communities encompassing a wide spectrum of Earth science disciplines. These include Data, Data-products, Services and Software (DDSS), from seismology, near fault observatories, geodetic observations, volcano observations, satellite observations, geomagnetic observations, as well as data from various anthropogenic hazard episodes, geological information and modelling. In addition, transnational access to multi-scale laboratories and geo-energy test-beds for low-carbon energy will be provided. TCS DDSS will be integrated into Integrated Core Services (ICS), a platform that will ensure their interoperability and access to these services by the scientific community as well as other users within the society. This requires dedicated tasks for interactions with the various TCS-WPs, as well as the various distributed ICS (ICS-Ds), such as High Performance Computing (HPC) facilities, large scale data storage

  13. Structural elucidation and magnetic behavior evaluation of rare earth (La, Nd, Gd, Tb, Dy) doped BaCoNi-X hexagonal nano-sized ferrites

    NASA Astrophysics Data System (ADS)

    Majeed, Abdul; Khan, Muhammad Azhar; Raheem, Faseeh ur; Hussain, Altaf; Iqbal, F.; Murtaza, Ghulam; Akhtar, Majid Niaz; Shakir, Imran; Warsi, Muhammad Farooq

    2016-06-01

    Rare-earth (RE=La3+, Nd3+, Gd3+, Tb3+, Dy3+) doped Ba2NiCoRExFe28-xO46 (x=0.25) hexagonal ferrites were synthesized for the first time via micro-emulsion route, which is a fast chemistry route for obtaining nano-sized ferrite powders. These nanomaterials were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), as well as vibrating sample magnetometer (VSM). The XRD analysis exhibited that all the samples crystallized into single X-type hexagonal phase. The crystalline size calculated by Scherrer's formula was found in the range 7-19 nm. The variations in lattice parameters elucidated the incorporation of rare-earth cations in these nanomaterials. FTIR absorption spectra of these X-type ferrites were investigated in the wave number range 500-2400 cm-1. Each spectrum exhibited absorption bands in the low wave number range, thereby confirming the X-type hexagonal structure. The enhancement in the coercivity was observed with the doping of rare-earth cations. The saturation magnetization was lowered owing to the redistribution of rare-earth cations on the octahedral site (3bVI). The higher values of coercivity (664-926 Oe) of these nanomaterials suggest their use in longitudinal recording media.

  14. Structural, morphological and spectroscopic properties of Eu{sup 3+}-doped rare earth fluorides synthesized by the hydrothermalmethod

    SciTech Connect

    Grzyb, Tomasz; Runowski, Marcin; Szczeszak, Agata; Lis, Stefan

    2013-04-15

    Rare earth fluorides (REF{sub 3}, RE=Y, La, Gd or Yb) doped with 5% of Eu{sup 3+} ions were synthesized via the hydrothermal method and their physicochemical properties were compared. The synthesis was carried out in an aqueous medium at elevated pressure and temperature. The reaction was performed in situ, with use of NaBF{sub 4} as a source of fluoride ions. Structural and morphological properties of obtained nanophosphors were characterized with the use of powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. Synthesized products were nanocrystalline with hexagonal or orthorhombic crystal structures. They showed different morphology, from nanoplates to nanorings, depending on the used REF{sub 3} fluoride as the host for the Eu{sup 3+} ions. The elemental composition was confirmed by the energy-dispersive X-ray spectroscopy (EDX) results. Spectroscopic properties were investigated by measuring the excitation and emission spectra. Also luminescence lifetimes were determined. The synthesized materials showed bright red luminescence, due to the presence of Eu{sup 3+} ions in their structure. - Graphical abstract: Luminescence spectra of the REF{sub 3}:Eu{sup 3+} (RE=Y, La, Gd and Yb) fluorides and their TEM images as background. Highlights: ► Nanocrystalline fluorides were synthesized using modified hydrothermal method. ► Structural and morphological properties of in situ prepared nanomaterials were studied. ► Luminescence properties of REF{sub 3}:Eu{sup 3+} (RE=Y, La, Gd, Yb) were compared and investigated.

  15. Enhanced Electroresponse of Alkaline Earth Metal-Doped Silica/Titania Spheres by Synergetic Effect of Dispersion Stability and Dielectric Property.

    PubMed

    Yoon, Chang-Min; Lee, Seungae; Cheong, Oug Jae; Jang, Jyongsik

    2015-09-01

    A series of alkaline earth metal-doped hollow SiO2/TiO2 spheres (EM-HST) are prepared as electrorheological (ER) materials via sonication-mediated etching method with various alkaline earth metal hydroxides as the etchant. The EM-HST spheres are assessed to determine how their hollow interior and metal-doping affects the ER activity. Both the dispersion stability and the dielectric properties of these materials are greatly enhanced by the proposed one-step etching method, which results in significant enhancement of ER activity. These improvements are attributed to increased particle mobility and interfacial polarization originating from the hollow nature of the EM-HST spheres and the effects of EM metal-doping. In particular, Ca-HST-based ER fluid exhibits ER performance which is 7.1-fold and 3.1-fold higher than those of nonhollow core/shell silica/titania (CS/ST) and undoped hollow silica/titania (HST)-based ER fluids, respectively. This study develops a versatile and simple approach to enhancing ER activity through synergetic effects arising from the combination of dispersion stability and the unique dielectric properties of hollow EM-HST spheres. In addition, the multigram scale production described in this experiment can be an excellent advantage for practical and commercial ER application.

  16. VUV spectroscopy of nominally pure and rare-earth ions doped LiCaAIF6 single crystals as promising materials for 157 nm photolithography

    NASA Astrophysics Data System (ADS)

    Cefalas, Alkiviadis C.; Sarantopoulou, Evangelia; Kollia, Z.; Abdulsabirov, R. Y.; Korableva, S. L.; Naumov, A. K.; Semashko, V. V.; Kobe, S.; McGuiness, P. J.

    2002-07-01

    Recently it was found that birefringence is induced in CaF2 crystals when they are illuminated with laser light at 157 nm. Taking into consideration that CaF2 is the only optical material used in 157 nm photolithography today, the possibility to use new wide band gap fluoride crystals as optical elements for 157 nm photolithography, even those of non-cubic symmetry, should be considered. Additionally fluoride dielectric crystals with wide band gaps doped with trivalent rare-earth (RE) ions can be used as passive or active optical elements int eh VUV. For doped crystals, applications depend on the structure of the energy level pattern of the 4fn-15d electronic configuration and RE ion concentration. In this work we are exploiting the use of wide band gap fluoride dielectric crystals doped with RE ions. The laser induced fluorescence spectrum at 157 nm, and the absorption spectra of the LiCaAlF6 crystals, pure and doped with RE ions, were investigated in the VUV region of the spectrum. A new m4tehod for monitoring RE concentration in wide band gap fluoride crystals, that is based on vibrating sample magnetometer measurement is presented as well.

  17. Information Requirements for Integrating Spatially Discrete, Feature-Based Earth Observations

    NASA Astrophysics Data System (ADS)

    Horsburgh, J. S.; Aufdenkampe, A. K.; Lehnert, K. A.; Mayorga, E.; Hsu, L.; Song, L.; Zaslavsky, I.; Valentine, D. L.

    2014-12-01

    Several cyberinfrastructures have emerged for sharing observational data collected at densely sampled and/or highly instrumented field sites. These include the CUAHSI Hydrologic Information System (HIS), the Critical Zone Observatory Integrated Data Management System (CZOData), the Integrated Earth Data Applications (IEDA) and EarthChem system, and the Integrated Ocean Observing System (IOOS). These systems rely on standard data encodings and, in some cases, standard semantics for classes of geoscience data. Their focus is on sharing data on the Internet via web services in domain specific encodings or markup languages. While they have made progress in making data available, it still takes investigators significant effort to discover and access datasets from multiple repositories because of inconsistencies in the way domain systems describe, encode, and share data. Yet, there are many scenarios that require efficient integration of these data types across different domains. For example, understanding a soil profile's geochemical response to extreme weather events requires integration of hydrologic and atmospheric time series with geochemical data from soil samples collected over various depth intervals from soil cores or pits at different positions on a landscape. Integrated access to and analysis of data for such studies are hindered because common characteristics of data, including time, location, provenance, methods, and units are described differently within different systems. Integration requires syntactic and semantic translations that can be manual, error-prone, and lossy. We report information requirements identified as part of our work to define an information model for a broad class of earth science data - i.e., spatially-discrete, feature-based earth observations resulting from in-situ sensors and environmental samples. We sought to answer the question: "What information must accompany observational data for them to be archivable and discoverable within

  18. VARIABILITY OF WATER AND OXYGEN ABSORPTION BANDS IN THE DISK-INTEGRATED SPECTRA OF EARTH

    SciTech Connect

    Fujii, Yuka; Suto, Yasushi; Turner, Edwin L.

    2013-03-10

    We study the variability of major atmospheric absorption features in the disk-integrated spectra of Earth with future application to Earth-analogs in mind, concentrating on the diurnal timescale. We first analyze observations of Earth provided by the EPOXI mission, and find 5%-20% fractional variation of the absorption depths of H{sub 2}O and O{sub 2} bands, two molecules that have major signatures in the observed range. From a correlation analysis with the cloud map data from the Earth Observing Satellite (EOS), we find that their variation pattern is primarily due to the uneven cloud cover distribution. In order to account for the observed variation quantitatively, we consider a simple opaque cloud model, which assumes that the clouds totally block the spectral influence of the atmosphere below the cloud layer, equivalent to assuming that the incident light is completely scattered at the cloud top level. The model is reasonably successful, and reproduces the EPOXI data from the pixel-level EOS cloud/water vapor data. A difference in the diurnal variability patterns of H{sub 2}O and O{sub 2} bands is ascribed to the differing vertical and horizontal distribution of those molecular species in the atmosphere. On Earth, the inhomogeneous distribution of atmospheric water vapor is due to the existence of its exchange with liquid and solid phases of H{sub 2}O on the planet's surface on a timescale short compared with atmospheric mixing times. If such differences in variability patterns were detected in spectra of Earth-analogs, it would provide the information on the inhomogeneous composition of their atmospheres.

  19. The integrated Earth System Model (iESM): formulation and functionality

    DOE PAGES

    Collins, W. D.; Craig, A. P.; Truesdale, J. E.; Di Vittorio, A. V.; Jones, A. D.; Bond-Lamberty, B.; Calvin, K. V.; Edmonds, J. A.; Kim, S. H.; Thomson, A. M.; et al

    2015-01-21

    The integrated Earth System Model (iESM) has been developed as a new tool for projecting the joint human/climate system. The iESM is based upon coupling an Integrated Assessment Model (IAM) and an Earth System Model (ESM) into a common modeling infrastructure. IAMs are the primary tool for describing the human–Earth system, including the sources of global greenhouse gases (GHGs) and short-lived species, land use and land cover change, and other resource-related drivers of anthropogenic climate change. ESMs are the primary scientific tools for examining the physical, chemical, and biogeochemical impacts of human-induced changes to the climate system. The iESM projectmore » integrates the economic and human dimension modeling of an IAM and a fully coupled ESM within a single simulation system while maintaining the separability of each model if needed. Both IAM and ESM codes are developed and used by large communities and have been extensively applied in recent national and international climate assessments. By introducing heretofore-omitted feedbacks between natural and societal drivers, we can improve scientific understanding of the human–Earth system dynamics. Potential applications include studies of the interactions and feedbacks leading to the timing, scale, and geographic distribution of emissions trajectories and other human influences, corresponding climate effects, and the subsequent impacts of a changing climate on human and natural systems. This paper describes the formulation, requirements, implementation, testing, and resulting functionality of the first version of the iESM released to the global climate community.« less

  20. Fostering Earth Observation Regional Networks - Integrative and iterative approaches to capacity building

    NASA Astrophysics Data System (ADS)

    Habtezion, S.

    2015-12-01

    Fostering Earth Observation Regional Networks - Integrative and iterative approaches to capacity building Fostering Earth Observation Regional Networks - Integrative and iterative approaches to capacity building Senay Habtezion (shabtezion@start.org) / Hassan Virji (hvirji@start.org)Global Change SySTem for Analysis, Training and Research (START) (www.start.org) 2000 Florida Avenue NW, Suite 200 Washington, DC 20009 USA As part of the Global Observation of Forest and Land Cover Dynamics (GOFC-GOLD) project partnership effort to promote use of earth observations in advancing scientific knowledge, START works to bridge capacity needs related to earth observations (EOs) and their applications in the developing world. GOFC-GOLD regional networks, fostered through the support of regional and thematic workshops, have been successful in (1) enabling participation of scientists for developing countries and from the US to collaborate on key GOFC-GOLD and Land Cover and Land Use Change (LCLUC) issues, including NASA Global Data Set validation and (2) training young developing country scientists to gain key skills in EOs data management and analysis. Members of the regional networks are also engaged and reengaged in other EOs programs (e.g. visiting scientists program; data initiative fellowship programs at the USGS EROS Center and Boston University), which has helped strengthen these networks. The presentation draws from these experiences in advocating for integrative and iterative approaches to capacity building through the lens of the GOFC-GOLD partnership effort. Specifically, this presentation describes the role of the GODC-GOLD partnership in nurturing organic networks of scientists and EOs practitioners in Asia, Africa, Eastern Europe and Latin America.

  1. PHOTOMETRIC VARIABILITY OF THE DISK-INTEGRATED THERMAL EMISSION OF THE EARTH

    SciTech Connect

    Gomez-Leal, I.; Selsis, F.; Palle, E. E-mail: selsis@obs.u-bordeaux1.fr

    2012-06-10

    Here we present an analysis of the global-integrated mid-infrared emission flux of the Earth based on data derived from satellite measurements. We have studied the photometric annual, seasonal, and rotational variability of the thermal emission of the Earth to determine which properties can be inferred from the point-like signal. We find that the analysis of the time series allows us to determine the 24 hr rotational period of the planet for most observing geometries, due to large warm and cold areas, identified with geographic features, which appear consecutively in the observer's planetary view. However, the effects of global-scale meteorology can effectively mask the rotation for several days at a time. We also find that orbital time series exhibit a seasonal modulation, whose amplitude depends strongly on the latitude of the observer but weakly on its ecliptic longitude. As no systematic difference of brightness temperature is found between the dayside and the nightside, the phase variations of the Earth in the infrared range are negligible. Finally, we also conclude that the phase variation of a spatially unresolved Earth-Moon system is dominated by the lunar signal.

  2. Earth science information: Planning for the integration and use of global change information

    NASA Technical Reports Server (NTRS)

    Lousma, Jack R.

    1992-01-01

    The Consortium for International Earth Science Information Network (CIESIN) was founded in 1989 as a non-profit corporation dedicated to facilitating access to, use and understanding of global change information worldwide. The Consortium was created to cooperate and coordinate with organizations and researchers throughout the global change community to further access the most advanced technology, the latest scientific research, and the best information available for critical environmental decision making. CIESIN study efforts are guided by Congressional mandates to 'convene key present and potential users to assess the need for investment in integration of earth science information,' to 'outline the desirable pattern of interaction with the scientific and policy community,' and to 'develop recommendations and draft plans to achieve the appropriate level of effort in the use of earth science data for research and public policy purposes.' In addition, CIESIN is tasked by NASA to develop a data center that would extend the benefits of Earth Observing System (EOS) to the users of global change information related to human dimensions issues. For FY 1991, CIESIN focused on two main objectives. The first addressed the identification of information needs of global change research and non-research user groups worldwide. The second focused on an evaluation of the most efficient mechanisms for making this information available in usable forms.

  3. Practices of Integrating the Earth Charter into Education Activities in German Federal States of Hessen and Rheinland-Pfalz

    ERIC Educational Resources Information Center

    Mathar, Reiner

    2010-01-01

    The integration of Earth Charter into everyday practice of schools in Germany has to be combined with the curriculum development in different subjects. Two states of Germany started this process by organizing inservice training for primary and secondary teachers. Additionally they translated and adopted the Earth Charter Teachers Guidebook to…

  4. Synthesis and luminescent properties of rare earth (Sm3+ and Eu3+) Doped Gd2Ti2O7 pyrochlore nanopowders

    NASA Astrophysics Data System (ADS)

    Ćulubrk, Sanja; Antić, Željka; Marinović-Cincović, Milena; Ahrenkiel, Phillip S.; Dramićanin, Miroslav D.

    2014-11-01

    This work describes the synthesis and photoluminescent properties of rare earth (Sm3+ and Eu3+) doped Gd2Ti2O7 pyrochlore nanopowders. Pure-phase rare earth-doped Gd2Ti2O7 nanoparticles of approximately 20-50 nm in diameter, as evidenced from X-ray diffraction and electron microscopy analysis, are produced via the mixed metal-citric acid complex method. A temperature of 880 °C is identified for the formation of the crystalline pyrochlore phase, based on a differential thermal analysis of Gd2Ti2O7 precursor gels. From photoluminescence excitation and emission spectra, measured at 10 K and room temperature, the energy levels of Sm3+ and Eu3+ ions in Gd2Ti2O7 nanoparticles are obtained. The dependence of luminescence emission intensity and emission decays on rare earth concentration are measured and discussed. The strongest Sm3+ orange-reddish emission is observed for samples containing 2.5 at.% of Sm3+ ions, while in the case of Eu3+, the most intense emission is found for 15 at.% Eu3+ doping. The 4G5/2 level lifetime decreases with an increase in Sm3+ concentration, from about 5 ms (for 0.1-0.2 at.% of Sm3+) to 2.4 ms (for 2.5 at.% of Sm3+). With an increase in Eu3+ concentration in the Gd2Ti2O7 nanoparticles, the Eu3+5D0 level lifetime decreases from ∼5.9 ms (for 0.5 at.% of Sm3+) to 3.1 ms (for 15 at.% of Sm3+).

  5. INTEGRATION OF THE ROTATION OF AN EARTH-LIKE BODY AS A PERTURBED SPHERICAL ROTOR

    SciTech Connect

    Ferrer, Sebastian; Lara, Martin E-mail: mlara@roa.e

    2010-05-15

    For rigid bodies close to a sphere, we propose an analytical solution that is free from elliptic integrals and functions, and can be fundamental for application to perturbed problems. After reordering the Hamiltonian as a perturbed spherical rotor, the Lie-series solution is generated up to an arbitrary order. Using the inertia parameters of different solar system bodies, the comparison of the approximate series solution with the exact analytical one shows that the precision reached with relatively low orders is at the same level of the observational accuracy for the Earth and Mars. Thus, for instance, the periodic errors of the mathematical solution are confined to the microarcsecond level with a simple second-order truncation for the Earth. On the contrary, higher orders are required for the mathematical solution to reach a precision at the expected level of accuracy of proposed new theories for the rotational dynamics of the Moon.

  6. From the Earth Summit to Rio+20: integration of health and sustainable development.

    PubMed

    Haines, Andy; Alleyne, George; Kickbusch, Ilona; Dora, Carlos

    2012-06-01

    In 2012, world leaders will meet at the Rio+20 conference to advance sustainable development--20 years after the Earth Summit that resulted in agreement on important principles but insufficient action. Many of the development goals have not been achieved partly because social (including health), economic, and environmental priorities have not been addressed in an integrated manner. Adverse trends have been reported in many key environmental indicators that have worsened since the Earth Summit. Substantial economic growth has occurred in many regions but nevertheless has not benefited many populations of low income and those that have been marginalised, and has resulted in growing inequities. Variable progress in health has been made, and inequities are persistent. Improved health contributes to development and is underpinned by ecosystem stability and equitable economic progress. Implementation of policies that both improve health and promote sustainable development is urgently needed.

  7. Wide frequencies range of spin excitations in a rare-earth Bi-doped iron garnet with a giant Faraday rotation

    NASA Astrophysics Data System (ADS)

    Parchenko, Sergii; Stupakiewicz, Andrzej; Yoshimine, Isao; Satoh, Takuya; Maziewski, Andrzej

    2013-10-01

    Ultrafast magnetization dynamics of a rare-earth Bi-doped garnet were studied using an optical pump-probe technique via the inverse Faraday effect. We observed a wide range of frequency modes of the magnetization precession, covering two orders of magnitude. The excitation efficiency of low-frequency precessions in the GHz range, together with a significant beating effect, strongly depended on the amplitude of the external magnetic field. On the contrary, high-frequency precession was independent of the external magnetic field. The obtained results may be exploited in the development of wide class of microwave and magneto-optical devices.

  8. Facile fabrication and photoluminescence properties of rare-earth-doped Gd₂O₃ hollow spheres via a sacrificial template method.

    PubMed

    Gao, Yu; Zhao, Qian; Fang, Qinghong; Xu, Zhenhe

    2013-08-21

    Rare-earth-doped gadolinium oxide (Gd₂O₃) hollow spheres were successfully fabricated on a large scale by using PS spheres as sacrificed templates and urea as a precipitating agent, which involved the deposition of an inorganic coating Gd(OH)CO3 on the surface of PS spheres and subsequent calcination in the air. Various approaches including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), as well as photoluminescence spectroscopies were used to characterize the samples. The results indicate that the sample is composed of uniform hollow Gd₂O₃ spheres with a mean particle size of about 2.3 μm and these hollow spheres have the mesoporous shell that are composed of a large amount of nanoparticles. The possible mechanism of evolution from PS spheres to the amorphous precursor and to the final hollow Gd₂O₃ spheres have been proposed. The as-obtained samples show strong light emission with different colors corresponding to different Ln³⁺ ions under ultraviolet-visible light and electron-beam excitation. Under 980 nm NIR irradiation, Gd₂O₃:Ln³⁺ (Ln³⁺ = Yb³⁺/Er³⁺, Yb³⁺/Tm³⁺ and Yb³⁺/Ho³⁺) exhibit characteristic up-conversion (UC) emissions of red (Er³⁺, ²H11/2, ⁴S3/2, ⁴F9/2 → ⁴I15/2), blue (Tm³⁺, ¹G₄ → ³H₆) and green (Ho³⁺, ⁵F₄, ⁵S₂ → ⁵I₈), respectively. These merits of multicolor emissions in the visible region endow these kinds of materials with potential applications in the field of light display systems, lasers, optoelectronic devices, and MRI contrast agents.

  9. Rare-earth-ion-doped Al IIO 3 waveguides for active integrated optical devices

    NASA Astrophysics Data System (ADS)

    Bradley, Jonathan D. B.; Ay, Feridun; Blauwendraat, Tom; Wörhoff, Kerstin; Pollnau, Markus

    2007-06-01

    Reactively co-sputtered amorphous Al IIO 3 waveguide layers with low propagation losses have been deposited. In order to define channel waveguides in such Al IIO 3 films, the etching behaviour of Al IIO 3 has been investigated using an inductively coupled reactive ion etch system. The etch rate of Al IIO 3 and possible mask materials was studied by applying various common process gases and combinations of these gases, including CF 4/O II, BCl 3, BCl 3/HBr and Cl II. Based on a comparison of the etch rates and patterning feasibility of the different mask materials, a BCl 3/HBr plasma and and standard resist mask were used to fabricate channel waveguide structures. The etched structures exhibit straight sidewalls with minimal roughness and etch depths of up to 530 nm, sufficient for defining waveguides with strong optical confinement and low bending losses. Low additional propagation losses were measured in single-mode Al IIO 3 ridge waveguides defined using the developed etch process. In initial investigations, Al IIO 3:Er layers fabricated using the same deposition method applied for the undoped layers show typical emission cross-sections, low green upconversion luminescence and lifetimes up to 7 ms.

  10. Earth Systems Science in an Integrated Science Content and Methods Course for Elementary Education Majors

    NASA Astrophysics Data System (ADS)

    Madsen, J. A.; Allen, D. E.; Donham, R. S.; Fifield, S. J.; Shipman, H. L.; Ford, D. J.; Dagher, Z. R.

    2004-12-01

    With funding from the National Science Foundation, we have designed an integrated science content and methods course for sophomore-level elementary teacher education (ETE) majors. This course, the Science Semester, is a 15-credit sequence that consists of three science content courses (Earth, Life, and Physical Science) and a science teaching methods course. The goal of this integrated science and education methods curriculum is to foster holistic understandings of science and pedagogy that future elementary teachers need to effectively use inquiry-based approaches in teaching science in their classrooms. During the Science Semester, traditional subject matter boundaries are crossed to stress shared themes that teachers must understand to teach standards-based elementary science. Exemplary approaches that support both learning science and learning how to teach science are used. In the science courses, students work collaboratively on multidisciplinary problem-based learning (PBL) activities that place science concepts in authentic contexts and build learning skills. In the methods course, students critically explore the theory and practice of elementary science teaching, drawing on their shared experiences of inquiry learning in the science courses. An earth system science approach is ideally adapted for the integrated, inquiry-based learning that takes place during the Science Semester. The PBL investigations that are the hallmark of the Science Semester provide the backdrop through which fundamental earth system interactions can be studied. For example in the PBL investigation that focuses on energy, the carbon cycle is examined as it relates to fossil fuels. In another PBL investigation centered on kids, cancer, and the environment, the hydrologic cycle with emphasis on surface runoff and ground water contamination is studied. In a PBL investigation that has students learning about the Delaware Bay ecosystem through the story of the horseshoe crab and the biome

  11. Crystal growth, characterization and theoretical studies of alkaline earth metal-doped tetrakis(thiourea)nickel(II) chloride.

    PubMed

    Agilandeshwari, R; Muthu, K; Meenatchi, V; Meena, K; Rajasekar, M; Aditya Prasad, A; Meenakshisundaram, S P

    2015-02-25

    The influence of Sr(II)-doping on the properties of tetrakis(thiourea)nickel(II) chloride (TTNC) has been described. The reduction in the intensity observed in powder X-ray diffraction of doped specimen and slight shifts in vibrational frequencies of doped specimens confirm the lattice stress as a result of doping. Surface morphological changes due to doping of the Sr(II) are observed by scanning electron microscopy. The incorporation of metal into the host crystal lattice was confirmed by energy dispersive X-ray spectroscopy. Lattice parameters are determined by single crystal XRD analysis. The thermogravimetric and differential thermal analysis studies reveal the purity of the materials and no decomposition is observed up to the melting point. The nonlinear optical properties of the doped and undoped specimens were studied. Theoretical calculations were performed using the Density functional theory (DFT) method with B3LYP/LANL2DZ as the basis set. The molecular geometry and vibrational frequencies of TTNC in the ground state were calculated and the observed structural parameters of TTNC are compared with parameters obtained from single crystal X-ray studies. The atomic charge distributions are obtained by Mulliken charge population analysis. The first-order molecular hyperpolarizability, polarizability and dipole moment were derived. PMID:25233030

  12. An integrated study of earth resources in the State of California using remote sensing techniques

    NASA Technical Reports Server (NTRS)

    Colwell, R. N.

    1972-01-01

    Remote sensing activities for the management of California's water project are reported. Integrated efforts are based largely on airborne remote sensing data processing to inventory the various kinds of earth resources observed. Work centered on defining parameters pertinent to determine water yield and discernible through remote sensing techniques; (2) determining accuracy in measuring and mapping parameters using remote sensing data flown to various specifications; and (3) relating water yield predictions to actual water yields. Remote sensing imagery of the Perris valley shows that land developers established a number of locations to promote present agricultural land for non-agricultural land use.

  13. Calcination-free liftoff photolithography of mixed dip-coated films consisting of rare-Earth-ion-doped nanoparticles on plastic sheets.

    PubMed

    Watanabe, Satoshi; Hyodo, Hiroshi; Taguchi, Hirohisa; Soga, Kohei; Takanashi, Yoshifumi; Matsumoto, Mutsuyoshi

    2012-01-01

    We discuss the calcination-free liftoff photolithography of inorganic phosphor films consisting of two kinds of rare-earth-ion-doped (RE) nanoparticles dip-coated onto plastic sheets. Green and red upconversion luminescence were emitted from the RE-nanoparticles prepared from Y₂O₃ nanoparticles doped with 1 mol% Er³⁺ and 0.75 mol% Yb³⁺ (RE-1-nanoparticles) and those doped with 3 mol% Er³⁺ and 7 mol% Yb³⁺ (RE-2-nanoparticles), respectively. Near-infrared (NIR) fluorescence was also observed in the RE-1- and RE-2-nanoparticles. The visible transmittance of the RE-nanoparticle films was more than 90%. The intensity ratio of the green to red upconversion luminescence was controlled by adjusting the mixing ratio of the RE-1- and RE-2-nanoparticles. These results indicate that the multicolor-emitting devices can be fabricated easily for applications of flexible inorganic phosphor films to displays, emitting devices, and sensors with long operating lifetimes and resistance to UV light, air, and water.

  14. Integrating emerging earth science technologies into disaster risk management: an enterprise architecture approach

    NASA Astrophysics Data System (ADS)

    Evans, J. D.; Hao, W.; Chettri, S. R.

    2014-12-01

    Disaster risk management has grown to rely on earth observations, multi-source data analysis, numerical modeling, and interagency information sharing. The practice and outcomes of disaster risk management will likely undergo further change as several emerging earth science technologies come of age: mobile devices; location-based services; ubiquitous sensors; drones; small satellites; satellite direct readout; Big Data analytics; cloud computing; Web services for predictive modeling, semantic reconciliation, and collaboration; and many others. Integrating these new technologies well requires developing and adapting them to meet current needs; but also rethinking current practice to draw on new capabilities to reach additional objectives. This requires a holistic view of the disaster risk management enterprise and of the analytical or operational capabilities afforded by these technologies. One helpful tool for this assessment, the GEOSS Architecture for the Use of Remote Sensing Products in Disaster Management and Risk Assessment (Evans & Moe, 2013), considers all phases of the disaster risk management lifecycle for a comprehensive set of natural hazard types, and outlines common clusters of activities and their use of information and computation resources. We are using these architectural views, together with insights from current practice, to highlight effective, interrelated roles for emerging earth science technologies in disaster risk management. These roles may be helpful in creating roadmaps for research and development investment at national and international levels.

  15. The Surface Temperatures of the Earth: Steps towards Integrated Understanding of Variability and Change

    NASA Astrophysics Data System (ADS)

    Matthiesen, Stephan; Merchant, Chris; Rayner, Nick; Remedios, John; Høyer, Jacob L.; Jones, Phil; Olesen, Folke; Roquet, Hervé; Sobrino, José; Thorne, Peter

    2013-04-01

    Surface temperature is a key aspect of weather and climate, relevant to human health, agriculture and leisure, ecosystem services, infrastructure development and economic activity. In a community-based activity, the EarthTemp Network brought together 55 researchers from 5 continents to improve the interaction between scientific communities who focus on particular domains, to exploit the strengths of different observing systems and to better meet the needs of different communities. The Network idenitified key needs for progress towards meeting societal needs for surface temperature understanding and information, which will be reviewed and discussed in this contribution. A "whole-Earth" perspective is required with more integrated, collaborative approaches to observing and understanding Earth's various surface temperatures. It is necessary to build understanding of the relationships of different surface temperatures, where presently inadequate, and undertake large-scale systematic intercomparisons. Datasets need to be easier to obtain and exploit for a wide constituency of users, with the differences and complementarities communicated in readily understood terms, and realistic and consistent uncertainty information. Steps are also recommended to curate and make available data that are presently inaccessible, develop new observing systems and build capacities to accelerate progress in the accuracy and usability of surface temperature datasets.

  16. Contributions to global earth sciences integration. A special issue on the 3rd Young Earth Scientists Congress

    NASA Astrophysics Data System (ADS)

    Cónsole-Gonella, Carlos; Yidana, Sandow Mark

    2016-10-01

    The Young Earth Scientists (YES) Network is an association of early-career geoscientists who are primarily under the age of 35 years from universities, geoscience organizations and companies from across the world (http://www.networkyes.org)

  17. Spherical-earth gravity and magnetic anomaly modeling by Gauss-Legendre quadrature integration

    NASA Technical Reports Server (NTRS)

    Von Frese, R. R. B.; Hinze, W. J.; Braile, L. W.; Luca, A. J.

    1981-01-01

    Gauss-Legendre quadrature integration is used to calculate the anomalous potential of gravity and magnetic fields and their spatial derivatives on a spherical earth. The procedure involves representation of the anomalous source as a distribution of equivalent point gravity poles or point magnetic dipoles. The distribution of equivalent point sources is determined directly from the volume limits of the anomalous body. The variable limits of integration for an arbitrarily shaped body are obtained from interpolations performed on a set of body points which approximate the body's surface envelope. The versatility of the method is shown by its ability to treat physical property variations within the source volume as well as variable magnetic fields over the source and observation surface. Examples are provided which illustrate the capabilities of the technique, including a preliminary modeling of potential field signatures for the Mississippi embayment crustal structure at 450 km.

  18. Earth science information: Planning for the integration and use of global change information

    NASA Technical Reports Server (NTRS)

    Lousma, Jack R.

    1992-01-01

    Activities and accomplishments of the first six months of the Consortium for International Earth Science Information Network (CIESIN's) 1992 technical program have focused on four main missions: (1) the development and implementation of plans for initiation of the Socioeconomic Data and Applications Center (SEDAC) as part of the EOSDIS Program; (2) the pursuit and development of a broad-based global change information cooperative by providing systems analysis and integration between natural science and social science data bases held by numerous federal agencies and other sources; (3) the fostering of scientific research into the human dimensions of global change and providing integration between natural science and social science data and information; and (4) the serving of CIESIN as a gateway for global change data and information distribution through development of the Global Change Research Information Office and other comprehensive knowledge sharing systems.

  19. Improving reservoir operations modeling for integration in a regional Earth system model

    NASA Astrophysics Data System (ADS)

    Voisin, N.; Li, H.; Ward, D. L.; Huang, M.; Leung, L.; Wigmosta, M. S.

    2012-12-01

    In integrated Earth system models (EaSMs), accurate hydrologic information in all of its components including socio-economy, atmosphere, land, and energy infrastructure is needed to represent the interactions between human and Earth system processes. The hydrology processes regulate the water, energy and carbon fluxes in this integrated framework. Human influence on the hydrologic cycle includes regulation and storage, consumptive use and overall redistribution of water resources in space and time. Representing these processes is essential for applications of EaSMs in hydrologic and climate predictions, as well as impact studies such as integrated assessment activities at regional to global scales. Dynamic programming approaches to optimize operations of reservoir systems have been widely used for water resources management planning at local and regional scales and recently have emerged in global-scale applications; albeit they are performed offline from the EaSMs , and require accurate knowledge of future flow for the upcoming water year. Other emerging large-scale research reservoir models use generic operating rules that are more flexible for coupling with EaSMs. Those generic operating rules have been successful in reproducing overall regulated flow at large basin scales. Improved generic operating rules are presented and evaluated across multiple spatial scales and objectives (flow but also storage and supply) over the complex multi-objective Columbia River Regulation System, which is representative of large river systems with increasing competitive reservoir purposes in the future. Challenges due to the difference in time and spatial scales between the physical processes versus reservoir operations and targets (irrigation, flood control, hydropower, environmental flow, navigation) are then discussed in the context of improving hydrology and evapotranspiration fluxes within an integrated EaSM.

  20. Earth Science Research Discovery, Integration, 3D Visualization and Analysis using NASA World Wind

    NASA Astrophysics Data System (ADS)

    Alameh, N.; Hogan, P.

    2008-12-01

    more possible to include virtual globe capability in support of any Earth science objective. 3- With the source code being fully accessible, anyone can advance this technology (including in a commercial or other proprietary manner). Such features enable World Wind to provide easy discovery, access and 3D integration/visualization/analysis of Earth observation data in a flexible, customizable open source tool. This positions World Wind to become a key part of an Advanced Information Systems infrastructure supporting a collaborative decision-making environment for a variety of applications.

  1. Towards a comprehensive model of Earth's disk-integrated Stokes vector

    NASA Astrophysics Data System (ADS)

    García Muñoz, A.

    2015-07-01

    A significant body of work on simulating the remote appearance of Earth-like exoplanets has been done over the last decade. The research is driven by the prospect of characterizing habitable planets beyond the Solar System in the near future. In this work, I present a method to produce the disk-integrated signature of planets that are described in their three-dimensional complexity, i.e. with both horizontal and vertical variations in the optical properties of their envelopes. The approach is based on Pre-conditioned Backward Monte Carlo integration of the vector Radiative Transport Equation and yields the full Stokes vector for outgoing reflected radiation. The method is demonstrated through selected examples inspired by published work at wavelengths from the visible to the near infrared and terrestrial prescriptions of both cloud and surface albedo maps. I explore the performance of the method in terms of computational time and accuracy. A clear strength of this approach is that its computational cost does not appear to be significantly affected by non-uniformities in the planet optical properties. Earth's simulated appearance is strongly dependent on wavelength; both brightness and polarization undergo diurnal variations arising from changes in the planet cover, but polarization yields a better insight into variations with phase angle. There is partial cancellation of the polarized signal from the northern and southern hemispheres so that the outgoing polarization vector lies preferentially either in the plane parallel or perpendicular to the planet scattering plane, also for non-uniform cloud and albedo properties and various levels of absorption within the atmosphere. The evaluation of circular polarization is challenging; a number of one-photon experiments of 109 or more is needed to resolve hemispherically integrated degrees of circular polarization of a few times 10-5. Last, I introduce brightness curves of Earth obtained with one of the Messenger cameras

  2. Scientific Research for Integrated Solutions to Community Challenges: The Thriving Earth Exchange (TEX) Approach

    NASA Astrophysics Data System (ADS)

    Udu-gama, N.; Pandya, R.

    2015-12-01

    There is tremendous unmet and sometimes unrealized need for Earth and space science (ESS) expertise as part of civic decisions and local planning for climate change, natural hazards and natural resources. The Thriving Earth Exchange (TEX) helps AGU contribute that expertise to humanity in respectful, integrated ways. TEX brings ESS scientists together with local communities tackling issues of climate change, natural hazards and natural resources to co-design solutions that equitably integrate both scientific and community knowledge. To achieve this ambitious goal, TEX is partnering with organizations that are respected by and knowledgeable about communities both in the United States and internationally. Such partnerships include Rockefeller's 100 Resilient Cities Initiative, ICLEI USA, MIT's Climate Colab, among others. TEX works with these partners to approach communities who are ready to or already addressing ESS related issues. With partners, we help the communities define their goals, develop specific projects, and connect with relevant and helpful ESS scientists. We will also show how we help scientists and community leaders work productively together, and the tools we bring to support their innovation. It will highlight international examples, such as in the Pamir Mountains of Afghanistan-Tajikistan, Sri Lanka, and Ethiopia, and provide concrete examples of how these initiatives are helping TEX further expand the frontiers of collaborative research.

  3. Comparing morphologies of drainage basins on Mars and Earth using integral-geometry and neural maps

    NASA Technical Reports Server (NTRS)

    Stepinski, T. F.; Coradetti, S.

    2004-01-01

    We compare morphologies of drainage basins on Mars and Earth in order to confine the formation process of Martian valley networks. Basins on both planets are computationally extracted from digital topography. Integral-geometry methods are used to represent each basin by a circularity function that encapsulates its internal structure. The shape of such a function is an indicator of the style of fluvial erosion. We use the self-organizing map technique to construct a similarity graph for all basins. The graph reveals systematic differences between morphologies of basins on the two planets. This dichotomy indicates that terrestrial and Martian surfaces were eroded differently. We argue that morphologies of Martian basins are incompatible with runoff from sustained, homogeneous rainfall. Fluvial environments compatible with observed morphologies are discussed. We also construct a similarity graph based on the comparison of basins hypsometric curves to demonstrate that hypsometry is incapable of discriminating between terrestrial and Martian basins. INDEX TERMS: 1824 Hydrology: Geomorphology (1625); 1886 Hydrology: Weathering (1625); 5415 Planetology: Solid Surface Planets: Erosion and weathering; 6225 Planetology: Solar System Objects Mars. Citation: Stepinski, T. F., and S. Coradetti (2004), Comparing morphologies of drainage basins on Mars and Earth using integral-ge

  4. Integration of Google Maps/Earth with microscale meteorology models and data visualization

    NASA Astrophysics Data System (ADS)

    Wang, Yansen; Huynh, Giap; Williamson, Chatt

    2013-12-01

    The Google Maps/Earth GIS has been integrated with a microscale meteorological model to improve the system's functionality and ease of use. Almost all the components of the model system, including the terrain data processing, morphological data generation, meteorological data gathering and initialization, and displaying/visualizing the model results, have been improved by using this approach. Different from the traditional stand-along model system, this novel system takes advantages of enormous resources in map and image data retrieving/handling, four-dimensional (space and time) data visualization, overlaying, and many other advanced GIS features that the Google Maps/Earth platform has to offer. We have developed modular components for all of the model system controls and data processing programs which are glued together with the JavaScript language and KML/XML data. We have also developed small modular software using the Google application program interface to convert the model results and intermediate data for visualizations and animations. Capabilities such as high-resolution image, street view, and 3D buildings in the Google Earth/Map are also used to quickly generate small-scale vegetation and building morphology data that are required for the microscale meteorological models. This system has also been applied to visualize the data from other instruments such as Doppler wind lidars. Because of the tight integration of the internet based GIS and a microscale meteorology model, the model system is more versatile, intuitive, and user-friendly than a stand-along system we had developed before. This kind of system will enhance the user experience and also help researchers to explore new phenomena in fine-scale meteorology.

  5. Luminescence quenching versus enhancement in WO3-NaPO3 glasses doped with trivalent rare earth ions and containing silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Dousti, M. Reza; Poirier, Gael Y.; Amjad, Raja J.; de Camargo, Andrea S. S.

    2016-10-01

    We report on the influence of silver nanoparticles (NPs) on the luminescence behavior of trivalent rare earth (RE) ion doped tungsten-phosphate glasses. In order to induce the growth of NPs, the as-prepared glass samples containing silver atoms, are exposed to heat-treatment above the glass transition temperature. The surface plasmon resonance band of the Ag NPs is observed in the visible range around 420 and 537 nm in the glasses with low and high tungsten content, respectively. Such difference in spectral shift of the plasmon band is attributed to the difference in the refractive index of the two studied glass compositions. Heat-treatment results in the general increase in number of NPs, while in the case of glasses with low tungsten content, it also imposes a shift to the Ag plasmon band. The NPs size distribution (4-10 nm) was determined in good agreement with the values obtained by using Mie theory and by transmission electron microscopy. The observed quenching in the visible luminescence of glasses doped with Eu3+, Tb3+ or Er3+is attributed to energy transfer from the RE ions to Ag species, while an enhanced near-infrared emission in Er3+ doped glasses is discussed in terms of the chemical contribution of silver, rather than the most commonly claimed enhancement of localized field or energy transfer from silver species to Er3+. The results are supported by the lifetime measurements. We believe that this study gives further insight and in-depth exploration of the somewhat controversial discussions on the influence of metallic NPs plasmonic effects in RE-doped glasses.

  6. Electrochemical Protein Cleavage in a Microfluidic Cell with Integrated Boron Doped Diamond Electrodes.

    PubMed

    van den Brink, Floris T G; Zhang, Tao; Ma, Liwei; Bomer, Johan; Odijk, Mathieu; Olthuis, Wouter; Permentier, Hjalmar P; Bischoff, Rainer; van den Berg, Albert

    2016-09-20

    Specific electrochemical cleavage of peptide bonds at the C-terminal side of tyrosine and tryptophan generates peptides amenable to liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis for protein identification. To this end we developed a microfluidic electrochemical cell of 160 nL volume that combines a cell geometry optimized for a high electrochemical conversion efficiency (>95%) with an integrated boron doped diamond (BDD) working electrode offering a wide potential window in aqueous solution and reduced adsorption of peptides and proteins. Efficient cleavage of the proteins bovine insulin and chicken egg white lysozyme was observed at 4 out of 4 and 7 out of 9 of the predicted cleavage sites, respectively. Chicken egg white lysozyme was identified based on 5 electrochemically generated peptides using a proteomics database searching algorithm. These results show that electrochemical peptide bond cleavage in a microfluidic cell is a novel, fully instrumental approach toward protein analysis and eventually proteomics studies in conjunction with mass spectrometry. PMID:27563730

  7. Department of Energy's Virtual Lab Infrastructure for Integrated Earth System Science Data

    NASA Astrophysics Data System (ADS)

    Williams, D. N.; Palanisamy, G.; Shipman, G.; Boden, T.; Voyles, J.

    2014-12-01

    The U.S. Department of Energy (DOE) Office of Biological and Environmental Research (BER) Climate and Environmental Sciences Division (CESD) produces a diversity of data, information, software, and model codes across its research and informatics programs and facilities. This information includes raw and reduced observational and instrumentation data, model codes, model-generated results, and integrated data products. Currently, most of this data and information are prepared and shared for program specific activities, corresponding to CESD organization research. A major challenge facing BER CESD is how best to inventory, integrate, and deliver these vast and diverse resources for the purpose of accelerating Earth system science research. This talk provides a concept for a CESD Integrated Data Ecosystem and an initial roadmap for its implementation to address this integration challenge in the "Big Data" domain. Towards this end, a new BER Virtual Laboratory Infrastructure will be presented, which will include services and software connecting the heterogeneous CESD data holdings, and constructed with open source software based on industry standards, protocols, and state-of-the-art technology.

  8. Integrating EarthScope seismic, GPS, and other active Earth observations into informal education programs in parks and museums

    NASA Astrophysics Data System (ADS)

    Lillie, R. J.; Goddard, C.; Braunmiller, J.; Trehu, A. M.

    2008-12-01

    EarthScope is a National Science Foundation program that uses seismic, GPS, and other geophysical devices to explore the structure and evolution of the North American continent and to understand the physical processes that cause earthquakes and volcanic eruptions. Two challenges facing the EarthScope community include providing the public with access to timely science results and presenting complex data and related principles in language and formats accessible to varied audiences. A series of workshops for park and museum educators combines scientific observations with interpretive methods to convey stories of the dynamic landscape of the western United States. The initial workshop, held at the Mt. Rainier National Park Education Center, focused on how EarthScope data and scientific results enhance the "sense of place" represented by the coastlines, valleys, and mountains of the Cascadia Subduction Zone. Participants learned how seismic and GPS instruments monitor earthquakes, volcanoes, and tsunamis that reveal the power of Earth's forces in the Pacific Northwest. A second workshop, held at the University of Nevada-Reno, related EarthScope observations to active continental rifting in the Basin and Range Province. Future workshops will focus on the San Andreas Fault, Colorado Plateau, Rio Grande Rift, and other regions. The workshops are helping interpretive professionals learn how observations of dynamic landscapes can be used to connect various audiences to many of the physical, historical, and cultural aspects of a park or museum site.

  9. Hydrogels dispersed by doped rare earth fluoride nanocrystals: ionic liquid dispersion and down/up-conversion luminescence.

    PubMed

    Yan, Zhi-Yuan; Jia, Li-Ping; Yan, Bing

    2014-01-01

    Two typical kinds of rare earth fluoride nanocrystals codoped with rare earth ions (Eu(3+) and Tm(3+)/Er(3+),Yb(3+)) are synthesized and dispersed in ionic liquid compound (1-chlorohexane-3-methylimidazolium chloride, abbreviated as [C6mim][Cl]). Assisted by agarose, the luminescent hydrogels are prepared homogeneously. The down/up-conversion luminescence of these hydrogels can be realized for the dispersed rare earth fluoride nanocrystals. The results provide a strategy to prepare luminescent (especially up-conversion luminescent) hydrogels with ionic liquid to disperse rare earth fluoride nanocrystals.

  10. The EPOS e-Infrastructure: Integrating Solid Earth Science in Europe

    NASA Astrophysics Data System (ADS)

    Trani, L.; Bailo, D.; Jeffery, K. G.

    2014-12-01

    The European Plate Observing System (EPOS) is an ambitious long term integration plan addressing the major solid-earth research infrastructures in Europe. For its large scale and extent it is a unique initiative which will foster new scientific discoveries and enable scientists to investigate the solid earth system in unprecedented ways. A key aspect of EPOS is to provide end-users with homogeneous access to services and multidisciplinary data collected by monitoring infrastructures and experimental facilities as well as access to processing and visualization tools. Such a complex system requires a solid, scalable and reliable architecture in order to accommodate innovative features and to meet the evolving expectations of the heterogeneous communities involved. Within the FP7 EU project EPOS PP1 (Preparatory Phase), which is approaching its completion in October 2014, the goal of the infrastructure and virtual community working group (WG7) was to design and test a preliminary architecture. The EPOS e-infrastructure architecture has been systematically developed based on collected primary (user) and secondary (interoperation with other systems) requirements and through three distinct design refinement phases (Strawman, Woodman and Ironman). The EPOS architecture is constituted of Integrated Core Services (ICS), which provide access to thematic (domain-specific) services (Thematic Core Services - TCS) integrating national research infrastructures. The key component of the architecture is the metadata catalogue, which utilizes the CERIF2(Common European Research Information Format) standard. The metadata catalogue is conceived to effectively capture all the information needed and to make large (re-)use of existing domain specific standards. In this contribution we will present the lessons learned and the technical achievements of the EPOS Preparatory Phase. 1www.epos-eu.org 2www.eurocris.org

  11. Self-Guided Field Explorations: Integrating Earth Science into Students' Lives

    NASA Astrophysics Data System (ADS)

    Kirkby, K. C.; Kirkby, S.

    2013-12-01

    Self-guided field explorations are a simple way to transform an earth science class into a more pedagogically effective experience. Previous experience demonstrated that self-guided student explorations of museum and aquarium exhibits were both extremely popular and remarkably effective. That success led our program to test an expansion of the concept to include self-guided student explorations in outdoor field settings. Preliminary assessment indicates these self-guided field explorations are nearly as popular with students as the museum and aquarium explorations and are as pedagogically effective. Student gains on post-instruction assessment match or exceed those seen in instructor-assisted, hands-on, small group laboratory activities and completely eclipse gains achieved by traditional lecture instruction. As importantly, self-guided field explorations provide a way to integrate field experiences into large enrollment courses where the sheer scale of class trips makes them logistically impossible. This expands course breadth, integrating new topics that could not be as effectively covered by the original class structure. Our introductory program assessed two models of self-guided field explorations. A walking/cycling exploration of the Saint Anthony Falls area, a mile from campus, focuses on the intersections of geological processes with human history. Students explore the geology behind the waterfalls' evolution as well as its subsequent social and economic impacts on human history. A second exploration focuses on the campus area geology, including its building stones as well as its landscape evolution. In both explorations, the goal was to integrate geology with the students' broader understanding of the world they live in. Although the explorations' creation requires a significant commitment, once developed, self-guided explorations are surprisingly low maintenance. These explorations provide a model of a simple, highly effective pedagogical tool that is

  12. Effect of knowledge integration activities on students' perception of the earth's crust as a cyclic system

    NASA Astrophysics Data System (ADS)

    Kali, Yael; Orion, Nir; Eylon, Bat-Sheva

    2003-08-01

    Systems thinking is regarded as a high-order thinking skill required in scientific, technological, and everyday domains. However, little is known about systems thinking in the context of science education. In the current research, students' understanding of the rock cycle system after a learning program was characterized, and the effect of a concluding knowledge integration activity on their systems thinking was studied. Answers to an open-ended test were interpreted using a systems thinking continuum, ranging from a completely static view of the system to an understanding of the system's cyclic nature. A meaningful improvement in students' views of the rock cycle toward the higher side of the systems thinking continuum was found after the knowledge integration activity. Students became more aware of the dynamic and cyclic nature of the rock cycle, and their ability to construct sequences of processes representing material transformation in relatively large chunks significantly improved. Success of the knowledge integration activity stresses the importance of postknowledge acquisition activities, which engage students in a dual process of differentiation of their knowledge and reintegration in a systems context. We suggest including such activities in curricula involving systems-based contents, particularly in earth science, in which systems thinking can bring about environmental literacy.

  13. Defect Clustering and Nano-Phase Structure Characterization of Multi-Component Rare Earth Oxide Doped Zirconia-Yttria Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Chen, Yuan L.; Miller, Robert A.

    1990-01-01

    Advanced oxide thermal barrier coatings have been developed by incorporating multi- component rare earth oxide dopants into zirconia-yttria to effectively promote the creation of the thermodynamically stable, immobile oxide defect clusters and/or nano-scale phases within the coating systems. The presence of these nano-sized defect clusters has found to significantly reduce the coating intrinsic thermal conductivity, improve sintering resistance, and maintain long-term high temperature stability. In this paper, the defect clusters and nano-structured phases, which were created by the addition of multi-component rare earth dopants to the plasma- sprayed and electron-beam physical vapor deposited thermal barrier coatings, were characterized by high-resolution transmission electron microscopy (TEM). The defect cluster size, distribution, crystallographic and compositional information were investigated using high-resolution TEM lattice imaging, selected area diffraction (SAD), and energy dispersive spectroscopy (EDS) analysis techniques. The results showed that substantial defect clusters were formed in the advanced multi-component rare earth oxide doped zirconia-yttria systems. The size of the oxide defect clusters and the cluster dopant segregation was typically ranging fiom 5 to 50 nm. These multi-component dopant induced defect clusters are an important factor for the coating long-term high temperature stability and excellent performance.

  14. Defect Clustering and Nano-Phase Structure Characterization of Multi-Component Rare Earth Oxide Doped Zirconia-Yttria Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Chen, Yuan L.; Miller, Robert A.

    2003-01-01

    Advanced oxide thermal barrier coatings have been developed by incorporating multi-component rare earth oxide dopants into zirconia-yttria to effectively promote the creation of the thermodynamically stable, immobile oxide defect clusters and/or nano-scale phases within the coating systems. The presence of these nano-sized defect clusters has found to significantly reduce the coating intrinsic thermal conductivity, improve sintering resistance, and maintain long-term high temperature stability. In this paper, the defect clusters and nano-structured phases, which were created by the addition of multi-component rare earth dopants to the plasma-sprayed and electron-beam physical vapor deposited thermal barrier coatings, were characterized by high-resolution transmission electron microscopy (TEM). The defect cluster size, distribution, crystallographic and compositional information were investigated using high-resolution TEM lattice imaging, selected area diffraction (SAD), electron energy-loss spectroscopy (EELS) and energy dispersive spectroscopy (EDS) analysis techniques. The results showed that substantial defect clusters were formed in the advanced multi-component rare earth oxide doped zirconia- yttria systems. The size of the oxide defect clusters and the cluster dopant segregation was typically ranging from 5 to 50 nm. These multi-component dopant induced defect clusters are an important factor for the coating long-term high temperature stability and excellent performance.

  15. Integrating Earth System Science Data Into Tribal College and University Curricula

    NASA Astrophysics Data System (ADS)

    Tilgner, P. J.; Perkey, D. J.

    2007-12-01

    , surface energy budgets, climate and climate change, impacts, etc. GIS and remote sensing training has focused on importing, converting and displaying data sets related to drought and fires. The Integrated Science courses at SGU, designed primarily for pre-service elementary teachers, have incorporated physical science concepts and teaching approaches presented at the TRESTE annual workshops. The content of the courses follows the PBL teaching approach and is organized around a relevant, local problem such as prairie dog control and prairie management. Concepts from Earth, life and physical sciences are included in the course design. The fall course is introduced using recent news articles on legislation to control prairie dogs. After expressing their ideas based solely on experience and emotion, students determine what knowledge they will need to write an informed opinion on the issue. One of the instructional units for the course includes instruction and practice in interpreting satellite images of the local reservation to determine impact of prairie dog towns on vegetation. Students also conduct soil studies in the disturbed areas and nearby undisturbed areas. Data is gathered on soil chemistry, soil temperatures, and surface temperatures, measured with an infrared sensor provided by the TRESTE grant. Additional topics covered in the course that contain information from the annual workshops, include prairie fires, climate and climate change, and effects of the drought on local bodies of water.

  16. Evaluating and improving CLM hydrologic processes for integrated earth system modeling at regional scales

    NASA Astrophysics Data System (ADS)

    Huang, M.; Leung, L.; Wigmosta, M. S.; Coleman, A. M.; Ke, Y.; Tesfa, T. K.; Li, H.

    2010-12-01

    The community land model (CLM) was designed for coupling with atmospheric models to simulate water, energy, and carbon fluxes between the land surface and atmosphere. These fluxes are regulated in various degrees by its hydrologic processes, which have not been vigorously evaluated for applications at watershed or regional scales. In the framework of an integrated regional earth system model being developed, accurate hydrologic information in all of its components including socio-economy, atmosphere, land, and energy infrastructure is needed to represent the interactions between human and earth system processes. Applying CLM in this framework requires evaluation and model improvement so that CLM could be used to represent hydrology, soil, managed and unmanaged ecosystems, and biogeochemical processes across scales in a single modeling framework. In this presentation, we will report preliminary results on the development of CLM featuring: (1) improved land surface hydrology that incorporates hydrologic processes from the Variable Infiltration Capacity (VIC) land surface model, including the parameterizations of subgrid variability, dynamic surface- and groundwater interactions, and hydraulic redistribution; (2) a semi-distributed extension of CLM (DCLM) for more spatially-explicit hydrologic modeling, which is critical for regional land and water management decisions under climate change mitigation and adaptation scenarios. The model development will be evaluated at flux towers and watersheds at various scales.

  17. Documenting the NASA Armstrong Flight Research Center Oblate Earth Simulation Equations of Motion and Integration Algorithm

    NASA Technical Reports Server (NTRS)

    Clarke, R.; Lintereur, L.; Bahm, C.

    2016-01-01

    A desire for more complete documentation of the National Aeronautics and Space Administration (NASA) Armstrong Flight Research Center (AFRC), Edwards, California legacy code used in the core simulation has led to this e ort to fully document the oblate Earth six-degree-of-freedom equations of motion and integration algorithm. The authors of this report have taken much of the earlier work of the simulation engineering group and used it as a jumping-o point for this report. The largest addition this report makes is that each element of the equations of motion is traced back to first principles and at no point is the reader forced to take an equation on faith alone. There are no discoveries of previously unknown principles contained in this report; this report is a collection and presentation of textbook principles. The value of this report is that those textbook principles are herein documented in standard nomenclature that matches the form of the computer code DERIVC. Previous handwritten notes are much of the backbone of this work, however, in almost every area, derivations are explicitly shown to assure the reader that the equations which make up the oblate Earth version of the computer routine, DERIVC, are correct.

  18. Integrated magnetometer-horizon sensor low-earth orbit determination using UKF

    NASA Astrophysics Data System (ADS)

    Farahanifar, Mohammad; Assadian, Nima

    2015-01-01

    The estimation of the satellite orbital elements using the integrated magnetometer and horizon sensors data has been investigated in this study. These sensors are generally employed for attitude estimation. The magnetometer and the horizon sensor measure the Earth's magnetic field as well as the Earth's center direction in the body frame, respectively. The magnitude of the magnetic field and the angle between two vectors have been used for orbit estimation purpose. This excludes the knowledge of the attitude in the orbit determination. The Gaussian variation of parameters equations is used for the orbital motion dynamical model to have the orbital elements as the states of the system. Since the dynamics of the system and the measurement model are nonlinear, the unscented Kalman filter (UKF) is utilized. Moreover, the magnetometer is subjected to scale factor and bias errors and these parameters are also estimated together with the orbital elements. It has been revealed that the UKF-based orbit determination algorithm can determine the sensor error parameters as well as the Keplerian orbital elements. The sensitivity analysis results show that this approach is insensitive to inclination and eccentricity for most orbits and can be adopted for near equatorial as well as near circular orbits.

  19. Spherical-earth Gravity and Magnetic Anomaly Modeling by Gauss-legendre Quadrature Integration

    NASA Technical Reports Server (NTRS)

    Vonfrese, R. R. B.; Hinze, W. J.; Braile, L. W.; Luca, A. J. (Principal Investigator)

    1981-01-01

    The anomalous potential of gravity and magnetic fields and their spatial derivatives on a spherical Earth for an arbitrary body represented by an equivalent point source distribution of gravity poles or magnetic dipoles were calculated. The distribution of equivalent point sources was determined directly from the coordinate limits of the source volume. Variable integration limits for an arbitrarily shaped body are derived from interpolation of points which approximate the body's surface envelope. The versatility of the method is enhanced by the ability to treat physical property variations within the source volume and to consider variable magnetic fields over the source and observation surface. A number of examples verify and illustrate the capabilities of the technique, including preliminary modeling of potential field signatures for Mississippi embayment crustal structure at satellite elevations.

  20. Integrating earth observations and model results provides earlier Famine Early Warning

    NASA Astrophysics Data System (ADS)

    Brown, M. E.; Funk, C. C.; Galu, G.; Choularton, R.

    2007-12-01

    Remote sensing allows us to detect slowly evolving natural hazards such as agricultural drought. Famine early warning systems transform this data into actionable policy information, enabling humanitarian organizations to respond in a timely and appropriate manner. These life saving responses are increasingly important. In 2006, 1 out of 8 people did not have enough to eat, 22 million more people became undernourished, and 22 countries provided 6.5 billion dollars in food aid. The motivation is strong, therefore, to increase the effectiveness of every dollar of food aid provided, ensuring that the assistance arrives sufficiently early to ward off human and economic catastrophe. Properly interpreted remote sensing information reduces the influence of politics in determining the amount and location of aid delivered. In this talk we will review three recent contributions that earth observations have provided to famine early warning: trend identification, increasingly accurate forecasts of food security conditions, and enhanced integration of biophysical and socio-economic data.

  1. CIM-EARTH: Community integrated model of economic and resource trajectories for humankind.

    SciTech Connect

    Elliott, J.; Foster, I.; Judd, K.; Moyer, E.; Munson, T.; Univ. of Chicago; Hoover Inst.

    2010-01-01

    Climate change is a global problem with local climatic and economic impacts. Mitigation policies can be applied on large geographic scales, such as a carbon cap-and-trade program for the entire U.S., on medium geographic scales, such as the NOx program for the northeastern U.S., or on smaller scales, such as statewide renewable portfolio standards and local gasoline taxes. To enable study of the environmental benefits, transition costs, capitalization effects, and other consequences of mitigation policies, we are developing dynamic general equilibrium models capable of incorporating important climate impacts. This report describes the economic framework we have developed and the current Community Integrated Model of Economic and Resource Trajectories for Humankind (CIM-EARTH) instance.

  2. Time-integrated photoluminescence and pump-probe reflection spectroscopy of Si doped InN thin films

    SciTech Connect

    Mohanta, Antaryami; Jang, Der-Jun Wang, Ming-Sung; Tu, L. W.

    2014-01-28

    Temperature and excitation power dependent time-integrated photoluminescence of Si doped InN thin films are investigated. Photoluminescence (PL) spectra at low temperatures are described by single emission peak ensued due to “free-to-bound” recombination; whereas PL spectra at higher temperatures above 150 K are characterized by both “band-to-band” and “free-to-bound” transition. Carrier dynamics of Si doped InN thin films is studied using pump-probe reflection spectroscopy at room temperature. The hot electron cooling process is well described by electron-electron scattering. The dependence of the hot electron cooling rate on total electron density shows sublinear to linear behavior with increase of background electron density. The variation of the carrier recombination lifetime with total electron density implicates the dominance of the defect-related nonradiative recombination channel over other recombination processes.

  3. DECADE web portal: toward the integration of MaGa, EarthChem and VOTW data systems to further the knowledge on Earth degassing

    NASA Astrophysics Data System (ADS)

    Cardellini, Carlo; Frigeri, Alessandro; Lehnert, Kerstin; Ash, Jason; McCormick, Brendan; Chiodini, Giovanni; Fischer, Tobias; Cottrell, Elizabeth

    2015-04-01

    The release of volatiles from the Earth's interior takes place in both volcanic and non-volcanic areas of the planet. The comprehension of such complex process and the improvement of the current estimates of global carbon emissions, will greatly benefit from the integration of geochemical, petrological and volcanological data. At present, major online data repositories relevant to studies of degassing are not linked and interoperable. In the framework of the Deep Earth Carbon Degassing (DECADE) initiative of the Deep Carbon Observatory (DCO), we are developing interoperability between three data systems that will make their data accessible via the DECADE portal: (1) the Smithsonian Institutionian's Global Volcanism Program database (VOTW) of volcanic activity data, (2) EarthChem databases for geochemical and geochronological data of rocks and melt inclusions, and (3) the MaGa database (Mapping Gas emissions) which contains compositional and flux data of gases released at volcanic and non-volcanic degassing sites. The DECADE web portal will create a powerful search engine of these databases from a single entry point and will return comprehensive multi-component datasets. A user will be able, for example, to obtain data relating to compositions of emitted gases, compositions and age of the erupted products and coincident activity, of a specific volcano. This level of capability requires a complete synergy between the databases, including availability of standard-based web services (WMS, WFS) at all data systems. Data and metadata can thus be extracted from each system without interfering with each database's local schema or being replicated to achieve integration at the DECADE web portal. The DECADE portal will enable new synoptic perspectives on the Earth degassing process allowing to explore Earth degassing related datasets over previously unexplored spatial or temporal ranges.

  4. Silver doping of silica-hafnia waveguides containing Tb3+/Yb3+ rare earths for downconversion in PV solar cells

    NASA Astrophysics Data System (ADS)

    Enrichi, F.; Armellini, C.; Battaglin, G.; Belluomo, F.; Belmokhtar, S.; Bouajaj, A.; Cattaruzza, E.; Ferrari, M.; Gonella, F.; Lukowiak, A.; Mardegan, M.; Polizzi, S.; Pontoglio, E.; Righini, G. C.; Sada, C.; Trave, E.; Zur, L.

    2016-10-01

    The aim of this paper is to study the possibility to obtain an efficient downconverting waveguide which combines the quantum cutting properties of Tb3+/Yb3+ codoped materials with the optical sensitizing effects provided by silver doping. The preparation of 70SiO2-30HfO2 glass and glass-ceramic waveguides by sol-gel route, followed by Ag doping by immersion in molten salt bath is reported. The films were subsequently annealed in air to induce the migration and/or aggregation of the metal ions. Results of compositional and optical characterization are given, providing evidence for the successful introduction of Ag in the films, while the photoluminescence emission is strongly dependent on the annealing conditions. These films could find potential applications as downshifting layers to increase the efficiency of PV solar cells.

  5. Rare-earth doped gadolinia based phosphors for potential multicolor and white light emitting deep UV LEDs

    NASA Astrophysics Data System (ADS)

    Bedekar, Vinila; Dutta, Dimple P.; Mohapatra, M.; Godbole, S. V.; Ghildiyal, R.; Tyagi, A. K.

    2009-03-01

    Gadolinium oxide host and europium/dysprosium/terbium doped gadolinium oxide nanoparticles were synthesized using the sonochemical technique. Gadolinium oxide nanocrystals were also co-doped with total 2 mol% of Eu3+/Dy3+,Eu3+/Tb3+,Dy3+/Tb3+, and also Eu3+/Dy3+/Tb3+ ions, by the same method. The nanoparticles obtained were characterized using powder x-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) techniques. The size of the particles ranged from 15 to 30 nm. The triple doped samples showed multicolor emission on single wavelength excitation. The photoluminescence results were correlated with the lifetime data to get an insight into the luminescence and energy transfer processes taking place in the system. On excitation at 247 nm, the novel nanocrystalline Gd2O3:RE (RE = Dy, Tb) phosphor resulted in having very impressive CIE chromaticity coordinates of x = 0.315 and y = 0.316, and a correlated color temperature of 6508 K, which is very close to standard daylight.

  6. Diamond-modified AFM probes: from diamond nanowires to atomic force microscopy-integrated boron-doped diamond electrodes.

    PubMed

    Smirnov, Waldemar; Kriele, Armin; Hoffmann, René; Sillero, Eugenio; Hees, Jakob; Williams, Oliver A; Yang, Nianjun; Kranz, Christine; Nebel, Christoph E

    2011-06-15

    In atomic force microscopy (AFM), sharp and wear-resistant tips are a critical issue. Regarding scanning electrochemical microscopy (SECM), electrodes are required to be mechanically and chemically stable. Diamond is the perfect candidate for both AFM probes as well as for electrode materials if doped, due to diamond's unrivaled mechanical, chemical, and electrochemical properties. In this study, standard AFM tips were overgrown with typically 300 nm thick nanocrystalline diamond (NCD) layers and modified to obtain ultra sharp diamond nanowire-based AFM probes and probes that were used for combined AFM-SECM measurements based on integrated boron-doped conductive diamond electrodes. Analysis of the resonance properties of the diamond overgrown AFM cantilevers showed increasing resonance frequencies with increasing diamond coating thicknesses (i.e., from 160 to 260 kHz). The measured data were compared to performed simulations and show excellent correlation. A strong enhancement of the quality factor upon overgrowth was also observed (120 to 710). AFM tips with integrated diamond nanowires are shown to have apex radii as small as 5 nm and where fabricated by selectively etching diamond in a plasma etching process using self-organized metal nanomasks. These scanning tips showed superior imaging performance as compared to standard Si-tips or commercially available diamond-coated tips. The high imaging resolution and low tip wear are demonstrated using tapping and contact mode AFM measurements by imaging ultra hard substrates and DNA. Furthermore, AFM probes were coated with conductive boron-doped and insulating diamond layers to achieve bifunctional AFM-SECM probes. For this, focused ion beam (FIB) technology was used to expose the boron-doped diamond as a recessed electrode near the apex of the scanning tip. Such a modified probe was used to perform proof-of-concept AFM-SECM measurements. The results show that high-quality diamond probes can be fabricated, which are

  7. Influence of Rare Earth Ho3+ Doping on Structural, Microstructure and Magnetic Properties of ZnO Bulk and Thin Film Systems

    NASA Astrophysics Data System (ADS)

    Murtaza Rai, Ghulam; Azhar Iqbal, Muhammad; Xu, Yongbing; Will, Iain Gordon; Zhang, Wen

    2011-06-01

    We have investigated the doping behavior of rare earth element holmium (Ho3+) in ZnO semiconductor. The structural, microstructure, and magnetic properties of Zn1-xHoxO (x=0.0, 0.04, and 0.05) thin films deposited on Si(100) substrate by thermal evaporation technique were studied. The ceramic targets were prepared by conventional solid state ceramic technique. The pallets used as target were final sintered at 900 °C in the presence of N2 atmosphere. The experimental results of X-ray diffraction (XRD) spectra, surface morphology, and magnetic properties show that the Ho3+ doped ZnO thin films has a strong influence on the materials properties. The higher angle shift in peak position and most preferred (101) orientation were observed in XRD pattern. These spectra confirmed the substitution of Ho3+ in ZnO lattice. The surface morphology and stoichiometry for both bulk and thin films were analyzed by scanning electron microscopy and energy dispersive spectroscopy. It was observed that grain size decreases with the increase of Ho3+. Room temperature ferromagnetism was observed for Zn0.95Ho0.05O films. The ferromagnetism might be attributed to the substitution of Ho ions for Zn2+ in ZnO lattices.

  8. White upconversion of rare-earth doped ZnO nanocrystals and its dependence on size of crystal particles and content of Yb3+ and Tm3+

    NASA Astrophysics Data System (ADS)

    Liu, Yunxin; Xu, Changfu; Yang, Qibin

    2009-04-01

    Rare earth (RE) doped ZnO nanocrystals were synthesized by chemical combustion method. Bright white upconversion (UC) luminescence with the CIE coordinates close to (0.33, 0.33) was obtained in Er+Tm+Yb tridoped ZnO nanocrystals under the excitation of a cost-effective 980 nm single-wavelength laser diode. The overall and relative UC luminescence intensities of RE doped ZnO nanocrystals were found to be depended highly on the diameter of crystal particles and the concentration of Yb3+ and Tm3+, for which the involved mechanisms were demonstrated. The investigation based on UC spectra, simplified energy level diagram, and excitation power dependence indicated that the remarkable enhancement of the green emission of the RE tridoped sample was due to a dual sensitization of Er3+ by Yb3+ and Tm3+ ions. The RE tridoped ZnO nanocrystals with the CIE coordinates close to (0.33, 0.33) are potentially suitable for the widely realistic application as the multicolor fluorescent labels, due to a fact that they could be cheaply and easily obtained and excited cost effectively.

  9. Integrated earth system dynamic modeling for life cycle impact assessment of ecosystem services.

    PubMed

    Arbault, Damien; Rivière, Mylène; Rugani, Benedetto; Benetto, Enrico; Tiruta-Barna, Ligia

    2014-02-15

    Despite the increasing awareness of our dependence on Ecosystem Services (ES), Life Cycle Impact Assessment (LCIA) does not explicitly and fully assess the damages caused by human activities on ES generation. Recent improvements in LCIA focus on specific cause-effect chains, mainly related to land use changes, leading to Characterization Factors (CFs) at the midpoint assessment level. However, despite the complexity and temporal dynamics of ES, current LCIA approaches consider the environmental mechanisms underneath ES to be independent from each other and devoid of dynamic character, leading to constant CFs whose representativeness is debatable. This paper takes a step forward and is aimed at demonstrating the feasibility of using an integrated earth system dynamic modeling perspective to retrieve time- and scenario-dependent CFs that consider the complex interlinkages between natural processes delivering ES. The GUMBO (Global Unified Metamodel of the Biosphere) model is used to quantify changes in ES production in physical terms - leading to midpoint CFs - and changes in human welfare indicators, which are considered here as endpoint CFs. The interpretation of the obtained results highlights the key methodological challenges to be solved to consider this approach as a robust alternative to the mainstream rationale currently adopted in LCIA. Further research should focus on increasing the granularity of environmental interventions in the modeling tools to match current standards in LCA and on adapting the conceptual approach to a spatially-explicit integrated model.

  10. Integrated earth system dynamic modeling for life cycle impact assessment of ecosystem services.

    PubMed

    Arbault, Damien; Rivière, Mylène; Rugani, Benedetto; Benetto, Enrico; Tiruta-Barna, Ligia

    2014-02-15

    Despite the increasing awareness of our dependence on Ecosystem Services (ES), Life Cycle Impact Assessment (LCIA) does not explicitly and fully assess the damages caused by human activities on ES generation. Recent improvements in LCIA focus on specific cause-effect chains, mainly related to land use changes, leading to Characterization Factors (CFs) at the midpoint assessment level. However, despite the complexity and temporal dynamics of ES, current LCIA approaches consider the environmental mechanisms underneath ES to be independent from each other and devoid of dynamic character, leading to constant CFs whose representativeness is debatable. This paper takes a step forward and is aimed at demonstrating the feasibility of using an integrated earth system dynamic modeling perspective to retrieve time- and scenario-dependent CFs that consider the complex interlinkages between natural processes delivering ES. The GUMBO (Global Unified Metamodel of the Biosphere) model is used to quantify changes in ES production in physical terms - leading to midpoint CFs - and changes in human welfare indicators, which are considered here as endpoint CFs. The interpretation of the obtained results highlights the key methodological challenges to be solved to consider this approach as a robust alternative to the mainstream rationale currently adopted in LCIA. Further research should focus on increasing the granularity of environmental interventions in the modeling tools to match current standards in LCA and on adapting the conceptual approach to a spatially-explicit integrated model. PMID:24291626

  11. Charge Compensation in RE3+ (RE = Eu, Gd) and M+ (M = Li, Na, K) Co-Doped Alkaline Earth Nanofluorides Obtained by Microwave Reaction with Reactive Ionic Liquids Leading to Improved Optical Properties

    SciTech Connect

    Lorbeer, C; Behrends, F; Cybinska, J; Eckert, H; Mudring, Anja -V

    2014-01-01

    Alkaline earth fluorides are extraordinarily promising host matrices for phosphor materials with regard to rare earth doping. In particular, quantum cutting materials, which might considerably enhance the efficiency of mercury-free fluorescent lamps or SC solar cells, are often based on rare earth containing crystalline fluorides such as NaGdF4, GdF3 or LaF3. Substituting most of the precious rare earth ions and simultaneously retaining the efficiency of the phosphor is a major goal. Alkaline earth fluoride nanoparticles doped with trivalent lanthanide ions (which are required for the quantum cutting phenomenon) were prepared via a microwave assisted method in ionic liquids. As doping trivalent ions into a host with divalent cations requires charge compensation, this effect was thoroughly studied by powder X-ray and electron diffraction, luminescence spectroscopy and 23Na, 139La and 19F solid state NMR spectroscopy. Monovalent alkali ions were codoped with the trivalent lanthanide ions to relieve stress and achieve a better crystallinity and higher quantum cutting abilities of the prepared material. 19F-magic angle spinning (MAS)-NMR-spectra, assisted by 19F{23Na} rotational echo double resonance (REDOR) studies, reveal distinct local fluoride environments, the populations of which are discussed in relation to spatial distribution and clustering models. In the co-doped samples, fluoride species having both Na+ and La3+ ions within their coordination sphere can be identified and quantified. This interplay of mono- and trivalent ions in the CaF2 lattice appears to be an efficient charge compensation mechanism that allows for improved performance characteristics of such co-doped phosphor materials.

  12. Integrated Earth Data Applications (IEDA) Tools for Data Management Plans and Data Compliance Reporting

    NASA Astrophysics Data System (ADS)

    Morton, J.; Ferrini, V.; Carbotte, S. M.; Lehnert, K. A.

    2012-12-01

    An important step in data stewardship is planning not only for how data will be acquired, processed and analyzed, but how data will be documented, preserved and shared. The Integrated Earth Data Applications (IEDA) Facility has developed multi-tiered web applications that assist investigators in both planning for data curation and demonstrating that their data has been made available. The IEDA Data Management Plan Tool is designed to help investigators create Data Management Plans for NSF proposals. It guides users through all relevant steps and allows them to provide relevant information about expected data types and products and select appropriate repositories for data curation. The product of the tool is a PDF that can be added to NSF proposals. A list of potential data repositories for a broad range of geoscience data types (geophysical, geochemical, climate, oceanographic, biological) is provided, but users can enter other repositories if desired. A dashboard interface allows users to manage multiple data management plans, retrieve previous versions, create new plans based on previous submissions, and link submitted plans to their funded NSF awards. A fully featured implementation of this tool is available at http://www.iedadata.org/compliance/plan. With an increasing focus on data compliance, IEDA is also developing a Data Compliance Reporting Tool. The Data Compliance Reporting Tool allows users to search for data inventoried within IEDA data systems (EarthChem and Marine Geoscience Data System) by award number and provides basic metadata and links to those data sets. In addition, links are provided to underway data acquired aboard the U.S. Academic Research Fleet (handled by the Rolling Deck to Repository Program), as well as related data that has been registered through the U.S. Antarctic Program Data Coordination Center. Future developments of this tool will include the ability for investigators to directly contribute additional information to update

  13. CIM-EARTH: Community Integrated Model of Economic and Resource Trajectories for Humankind

    NASA Astrophysics Data System (ADS)

    Foster, I.; Elliott, J.; Munson, T.; Judd, K.; Moyer, E. J.; Sanstad, A. H.

    2010-12-01

    We report here on the development of an open source software framework termed CIM-EARTH that is intended to aid decision-making in climate and energy policy. Numerical modeling in support of evaluating policies to address climate change is difficult not only because of inherent uncertainties but because of the differences in scale and modeling approach required for various subcomponents of the system. Economic and climate models are structured quite differently, and while climate forcing can be assumed to be roughly global, climate impacts and the human response to them occur on small spatial scales. Mitigation policies likewise can be applied on scales ranging from the better part of a continent (e.g. a carbon cap-and-trade program for the entire U.S.) to a few hundred km (e.g. statewide renewable portfolio standards and local gasoline taxes). Both spatial and time resolution requirements can be challenging for global economic models. CIM-EARTH is a modular framework based around dynamic general equilibrium models. It is designed as a community tool that will enable study of the environmental benefits, transition costs, capitalization effects, and other consequences of both mitigation policies and unchecked climate change. Modularity enables both integration of highly resolved component sub-models for energy and other key systems and also user-directed choice of tradeoffs between e.g. spatial, sectoral, and time resolution. This poster describes the framework architecture, the current realized version, and plans for future releases. As with other open-source models familiar to the climate community (e.g. CCSM), deliverables will be made publicly available on a regular schedule, and community input is solicited for development of new features and modules.

  14. Integration and Exposure of Large Scale Computational Resources Across the Earth System Grid Federation (ESGF)

    NASA Astrophysics Data System (ADS)

    Duffy, D.; Maxwell, T. P.; Doutriaux, C.; Williams, D. N.; Chaudhary, A.; Ames, S.

    2015-12-01

    As the size of remote sensing observations and model output data grows, the volume of the data has become overwhelming, even to many scientific experts. As societies are forced to better understand, mitigate, and adapt to climate changes, the combination of Earth observation data and global climate model projects is crucial to not only scientists but to policy makers, downstream applications, and even the public. Scientific progress on understanding climate is critically dependent on the availability of a reliable infrastructure that promotes data access, management, and provenance. The Earth System Grid Federation (ESGF) has created such an environment for the Intergovernmental Panel on Climate Change (IPCC). ESGF provides a federated global cyber infrastructure for data access and management of model outputs generated for the IPCC Assessment Reports (AR). The current generation of the ESGF federated grid allows consumers of the data to find and download data with limited capabilities for server-side processing. Since the amount of data for future AR is expected to grow dramatically, ESGF is working on integrating server-side analytics throughout the federation. The ESGF Compute Working Team (CWT) has created a Web Processing Service (WPS) Application Programming Interface (API) to enable access scalable computational resources. The API is the exposure point to high performance computing resources across the federation. Specifically, the API allows users to execute simple operations, such as maximum, minimum, average, and anomalies, on ESGF data without having to download the data. These operations are executed at the ESGF data node site with access to large amounts of parallel computing capabilities. This presentation will highlight the WPS API, its capabilities, provide implementation details, and discuss future developments.

  15. Integration of Earth Remote Sensing into the NOAA/NWS Damage Assessment Toolkit

    NASA Technical Reports Server (NTRS)

    Molthan, Andrew; Burks, Jason; Camp, Parks; McGrath, Kevin; Bell, Jordan

    2014-01-01

    Following the occurrence of severe weather, NOAA/NWS meteorologists are tasked with performing a storm damage survey to assess the type and severity of the weather event, primarily focused with the confirmation and assessment of tornadoes. This labor-intensive process requires meteorologists to venture into the affected area, acquire damage indicators through photos, eyewitness accounts, and other documentation, then aggregation of data in order to make a final determination of the tornado path length, width, maximum intensity, and other characteristics. Earth remote sensing from operational, polar-orbiting satellites can support the damage assessment process by helping to identify portions of damage tracks that are difficult to access due to road limitations or time constraints by applying change detection techniques. In addition, higher resolution commercial imagery can corroborate ground-based surveys by examining higher-resolution commercial imagery. As part of an ongoing collaboration, NASA and NOAA are working to integrate near real-time Earth remote sensing observations into the NOAA/NWS Damage Assessment Toolkit, a handheld application used by meteorologists in the survey process. The team has recently developed a more streamlined approach for delivering data via a web mapping service and menu interface, allowing for caching of imagery before field deployment. Near real-time products have been developed using MODIS and VIIRS imagery and change detection for preliminary track identification, along with conduits for higher-resolution Landsat, ASTER, and commercial imagery as they become available. In addition to tornado damage assessments, the team is also investigating the use of near real-time imagery for identifying hail damage to vegetation, which also results in large swaths of damage, particularly in the central United States during the peak growing season months of June, July, and August. This presentation will present an overview of recent activities

  16. Rare earth doped LiYbF{sub 4} phosphors with controlled morphologies: Hydrothermal synthesis and luminescent properties

    SciTech Connect

    Huang, Wenjuan; Lu, Chunhua; Jiang, Chenfei; Jin, Junyang; Ding, Mingye; Ni, Yaru; Xu, Zhongzi

    2012-06-15

    Highlights: ► LiYbF{sub 4} microparticles as an excellent upconverting materials. ► High temperature and long time can favor high crystalline LiYbF{sub 4} microparticles. ► The shape of LiYbF{sub 4} microparticles can be tuned by the molar ratio of EDTA to Yb{sup 3+}. ► Bright green emission can be obtained by changing the doping concentration of Er{sup 3+}. -- Abstract: High quality monodisperse LiYbF{sub 4} microparticles with shape of octahedron had been prepared via a facile hydrothermal route. The crystalline phase, size, morphology and luminescence properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectra and Commission Internationale de L’Eclairage (CIE 1931) chromaticity coordinates, respectively. The influences of reaction temperature, reaction time and the molar ratio of EDTA to Yb{sup 3+} on the crystal phases and shapes of as-prepared products had been investigated in detail. The upconversion (UC) luminescence properties of LiYb{sub 1−x}F{sub 4}:xEr{sup 3+} (x =0.1, 0.2, 0.5, 1, 2, 5 and 10 mol%) particles with octahedral microstructures were studied under 976 nm excitation. The results showed that the luminescence colors of the corresponding products could be tuned to bright green by changing the doping concentration of Er{sup 3+} ion. The luminescence mechanisms for the doped Er{sup 3+} ion were thoroughly analyzed, showing great potential in applications such as biolabels, displays and other optical technologies.

  17. Integration of lessons from recent research for “Earth to Mars” life support systems

    NASA Astrophysics Data System (ADS)

    Nelson, M.; Dempster, W. F.; Allen, J. P.

    adequate diet in space. This paper explores some of the challenges of small bioregenerative life support: air-sealing and facility architecture/design, balance of short-term variations of carbon dioxide and oxygen through staggered plantings, options for additional atmospheric buffers and sinks, lighting/energy efficiency engineering, crop and waste product recycling approaches, and human factor considerations in the design and operation of a Mars base. An "Earth to Mars" project, forging the ability to live sustainably in space (as on Earth) requires continued research and testing of these components and integrated subsystems; and developing a step-by-step learning process.

  18. Svalbard Integrated Arctic Earth Observing System - A New Coordinated Foundation for Environmental Services in and around Svalbard

    NASA Astrophysics Data System (ADS)

    Lilja Bye, Bente

    2015-04-01

    Svalbard Integrated Earth Observing System (SIOS) is an international infrastructure project. There were 28 partners from Europe and Asia involved in the preparatory phase of this ESFRI project. The essential objectives are to establish a mechanism for integration among the existing research institutions in Svalbard to create a joint state-of-the-art observing system in Earth System Science, and better coordinated services for the International Research community with respect to access, data and knowledge management, logistics and training. In addition to the SIOS members various data services, SIOS itself will provide a few new services such as processed satellite data (from Copernicus' Sentinels as well as others) and combined in-situ and satellite data. All in all SIOS represent a new capacity and foundation for more Earth System Science, including climate and environment, data services in and around Svalbard. A presentation of SIOS including time schedule for implementation of the basic services will be given.

  19. Effective Integration of the World-Wide Web in Earth Science Education.

    ERIC Educational Resources Information Center

    Herbert, Bruce; Bednarz, Sarah; Boyd, Tom; Blake, Sally; Harder, Vicki; Sutter, Marilyn

    The earth sciences is an evolving set of disciplines encompassing more than 30 specialties; however, earth scientists continue to be trained within the traditional disciplinary structure. Earth science education should focus not only on student acquisition and retention of factual knowledge, but also on the development of higher-order skills…

  20. Photon management properties of rare-earth (Nd,Yb,Sm)-doped CeO2 films prepared by pulsed laser deposition.

    PubMed

    Balestrieri, Matteo; Colis, Silviu; Gallart, Mathieu; Schmerber, Guy; Bazylewski, Paul; Chang, Gap Soo; Ziegler, Marc; Gilliot, Pierre; Slaoui, Abdelilah; Dinia, Aziz

    2016-01-28

    CeO2 is a promising material for applications in optoelectronics and photovoltaics due to its large band gap and values of the refractive index and lattice parameters, which are suitable for silicon-based devices. In this study, we show that trivalent Sm, Nd and Yb ions can be successfully inserted and optically activated in CeO2 films grown at a relatively low deposition temperature (400 °C), which is compatible with inorganic photovoltaics. CeO2 thin films can therefore be efficiently functionalized with photon-management properties by doping with trivalent rare earth (RE) ions. Structural and optical analyses provide details of the electronic level structure of the films and of their energy transfer mechanisms. In particular, we give evidence of the existence of an absorption band centered at 350 nm from which energy transfer to rare earth ions occurs. The transfer mechanisms can be completely explained only by considering the spontaneous migration of Ce(3+) ions in CeO2 at a short distance from the RE(3+) ions. The strong absorption cross section of the f-d transitions in Ce(3+) ions efficiently intercepts the UV photons of the solar spectrum and therefore strongly increases the potential of these layers as downshifters and downconverters.

  1. Double Rare-Earth Oxides Co-doped Strontium Zirconate as a New Thermal Barrier Coating Material

    NASA Astrophysics Data System (ADS)

    Ma, Wen; Wang, Dongxing; Dong, Hongying; Lun, Wenshan; He, Weiyan; Zheng, Xuebin

    2013-03-01

    Y2O3 and Yb2O3 co-doped strontium zirconate with chemistry of Sr(Zr0.9Y0.05Yb0.05)O2.95 (SZYY) was synthesized and had a minor second phase of Yb2O3. The SZYY showed good phase stability not only from room temperature to 1400 °C but also at high temperature of 1450 °C for a long period, analyzed by thermogravimetry-differential scanning calorimetry and x-ray diffraction, respectively. The coefficients of thermal expansion (CTEs) of the sintered bulk SZYY were recorded by a high-temperature dilatometer and revealed a positive influence on phase transitions of SrZrO3 by co-doping with Y2O3 and Yb2O3. The thermal conductivities of SZYY were at least ~30% lower in contrast to that of SrZrO3 and 8YSZ in the whole tested temperature range. Good chemical compatibility was observed for SZYY with 8YSZ or Al2O3 powders after a 24 h heat treatment at 1250 °C. The phase stability and the microstructure evolution of the as-sprayed SZYY coating during annealing at 1400 °C were also investigated.

  2. The COSPAR roadmap on Space-based observation and Integrated Earth System Science for 2016-2025

    NASA Astrophysics Data System (ADS)

    Fellous, Jean-Louis

    2016-07-01

    The Committee on Space Research of the International Council for Science recently commissioned a study group to prepare a roadmap on observation and integrated Earth-system science for the coming ten years. Its focus is on the combined use of observations and modelling to address the functioning, predictability and projected evolution of the Earth system on timescales out to a century or so. It discusses how observations support integrated Earth-system science and its applications, and identifies planned enhancements to the contributing observing systems and other requirements for observations and their processing. The paper will provide an overview of the content of the roadmap. All types of observation are considered in the roadmap, but emphasis is placed on those made from space. The origins and development of the integrated view of the Earth system are outlined, noting the interactions between the main components that lead to requirements for integrated science and modelling, and for the observations that guide and support them. What constitutes an Earth-system model is discussed. Summaries are given of key cycles within the Earth system. The nature of Earth observation and the arrangements for international coordination essential for effective operation of global observing systems are introduced in the roadmap. Instances are given of present types of observation, what is already on the roadmap for 2016-2025 and some of the issues to be faced. The current status and prospects for Earth-system modelling are summarized. Data assimilation is discussed not only because it uses observations and models to generate datasets for monitoring the Earth system and for initiating and evaluating predictions, in particular through reanalysis, but also because of the feedback it provides on the quality of both the observations and the models employed. Finally the roadmap offers a set of concluding discussions covering general developmental needs, requirements for continuity of

  3. Integrated solution for the complete remote sensing process - Earth Observation Mission Control Centre (EOMC2)

    NASA Astrophysics Data System (ADS)

    Czapski, Paweł

    2016-07-01

    We are going to show the latest achievements of the Remote Sensing Division of the Institute of Aviation in the area of remote sensing, i.e. the project of the integrated solution for the whole remote sensing process ranging from acquiring to providing the end user with required information. Currently, these tasks are partially performed by several centers in Poland, however there is no leader providing an integrated solution. Motivated by this fact, the Earth Observation Mission Control Centre (EOMC2) was established in the Remote Sensing Division of the Institute of Aviation that will provide such a comprehensive approach. Establishing of EOMC2 can be compared with creating Data Center Aerial and Satellite Data Centre (OPOLIS) in the Institute of Geodesy and Cartography in the mid-70s in Poland. OPOLIS was responsible for broadly defined data processing, it was a breakthrough innovation that initiated the use of aerial image analysis in Poland. Operation center is a part of the project that will be created, which in comparison with the competitors will provide better solutions, i.e.: • Centralization of the acquiring, processing, publishing and archiving of data, • Implementing elements of the INSPIRE directive recommendations on spatial data management, • Providing the end-user with information in the near real-time, • Ability of supplying the system with images of various origin (aerial, satellite, e.g. EUMETCast, Sentinel, Landsat) and diversity of telemetry data, data aggregation and using the same algorithms to images obtained from different sources, • System reconfiguration and batch processing of large data sets at any time, • A wide range of potential applications: precision agriculture, environmental protection, crisis management and national security, aerial, small satellite and sounding rocket missions monitoring.

  4. Integrating Parallel and Distributed Data Mining Algorithms into the NASA Earth Exchange (NEX)

    NASA Astrophysics Data System (ADS)

    Oza, N.; Kumar, V.; Nemani, R. R.; Boriah, S.; Das, K.; Khandelwal, A.; Matthews, B.; Michaelis, A.; Mithal, V.; Nayak, G.; Votava, P.

    2014-12-01

    There is an urgent need in global climate change science for efficient model and/or data analysis algorithms that can be deployed in distributed and parallel environments because of the proliferation of large and heterogeneous data sets. Members of our team from NASA Ames Research Center and the University of Minnesota have been developing new distributed data mining algorithms and developing distributed versions of algorithms originally developed to run on a single machine. We are integrating these algorithms together with the Terrestrial Observation and Prediction System (TOPS), an ecological nowcasting and forecasting system, on the NASA Earth Exchange (NEX). We are also developing a framework under which data mining algorithm developers can make their algorithms available for use by scientists in our system, model developers can set up their models to run within our system and make their results available, and data source providers can make their data available, all with as little effort as possible. We demonstrate the substantial time savings and new results that can be derived through this framework by demonstrating an improvement to the Burned Area (BA) data product on a global scale. Our improvement was derived through development and implementation on NEX of a novel spatiotemporal time series change detection algorithm which will also be presented.

  5. Integrated ray tracing simulation of annual variation of spectral bio-signatures from cloud free 3D optical Earth model

    NASA Astrophysics Data System (ADS)

    Ryu, Dongok; Kim, Sug-Whan; Kim, Dae Wook; Lee, Jae-Min; Lee, Hanshin; Park, Won Hyun; Seong, Sehyun; Ham, Sun-Jeong

    2010-09-01

    Understanding the Earth spectral bio-signatures provides an important reference datum for accurate de-convolution of collapsed spectral signals from potential earth-like planets of other star systems. This study presents a new ray tracing computation method including an improved 3D optical earth model constructed with the coastal line and vegetation distribution data from the Global Ecological Zone (GEZ) map. Using non-Lambertian bidirectional scattering distribution function (BSDF) models, the input earth surface model is characterized with three different scattering properties and their annual variations depending on monthly changes in vegetation distribution, sea ice coverage and illumination angle. The input atmosphere model consists of one layer with Rayleigh scattering model from the sea level to 100 km in altitude and its radiative transfer characteristics is computed for four seasons using the SMART codes. The ocean scattering model is a combination of sun-glint scattering and Lambertian scattering models. The land surface scattering is defined with the semi empirical parametric kernel method used for MODIS and POLDER missions. These three component models were integrated into the final Earth model that was then incorporated into the in-house built integrated ray tracing (IRT) model capable of computing both spectral imaging and radiative transfer performance of a hypothetical space instrument as it observes the Earth from its designated orbit. The IRT model simulation inputs include variation in earth orientation, illuminated phases, and seasonal sea ice and vegetation distribution. The trial simulation runs result in the annual variations in phase dependent disk averaged spectra (DAS) and its associated bio-signatures such as NDVI. The full computational details are presented together with the resulting annual variation in DAS and its associated bio-signatures.

  6. A mini-review on rare earth metal-doped TiO2 for photocatalytic remediation of wastewater.

    PubMed

    Saqib, Najm Us; Adnan, Rohana; Shah, Irfan

    2016-08-01

    Titanium dioxide (TiO2) has been considered a useful material for the treatment of wastewater due to its non-toxic character, chemical stability and excellent electrical and optical properties which contribute in its wide range of applications, particularly in environmental remediation technology. However, the wide band gap of TiO2 photocatalyst (anatase phase, 3.20 eV) limits its photocatalytic activity to the ultraviolet region of light. Besides that, the electron-hole pair recombination has been found to reduce the efficiency of the photocatalyst. To overcome these problems, tailoring of TiO2 surface with rare earth metals to improve its surface, optical and photocatalytic properties has been investigated by many researchers. The surface modifications with rare earth metals proved to enhance the efficiency of TiO2 photocatalyts by way of reducing the band gap by shifting the working wavelength to the visible region and inhibiting the anatase-to-rutile phase transformations. This review paper summarises the attempts on modification of TiO2 using rare earth metals describing their effect on the photocatalytic activities of the modified TiO2 photocatalyst. PMID:27335012

  7. A mini-review on rare earth metal-doped TiO2 for photocatalytic remediation of wastewater.

    PubMed

    Saqib, Najm Us; Adnan, Rohana; Shah, Irfan

    2016-08-01

    Titanium dioxide (TiO2) has been considered a useful material for the treatment of wastewater due to its non-toxic character, chemical stability and excellent electrical and optical properties which contribute in its wide range of applications, particularly in environmental remediation technology. However, the wide band gap of TiO2 photocatalyst (anatase phase, 3.20 eV) limits its photocatalytic activity to the ultraviolet region of light. Besides that, the electron-hole pair recombination has been found to reduce the efficiency of the photocatalyst. To overcome these problems, tailoring of TiO2 surface with rare earth metals to improve its surface, optical and photocatalytic properties has been investigated by many researchers. The surface modifications with rare earth metals proved to enhance the efficiency of TiO2 photocatalyts by way of reducing the band gap by shifting the working wavelength to the visible region and inhibiting the anatase-to-rutile phase transformations. This review paper summarises the attempts on modification of TiO2 using rare earth metals describing their effect on the photocatalytic activities of the modified TiO2 photocatalyst.

  8. MEOS Microsatellite Earth Observation using Miniature Integrated-Optic IR Spectrometers

    NASA Astrophysics Data System (ADS)

    Kruzelecky, Roman

    Our planetary atmosphere helps to regulate the Earth's thermal budget and the resulting global climate by controlling the energy balance between the incident solar radiation and the thermal emission to space from the Earth's atmosphere and surface. Certain atmospheric gases, most importantly H2 O vapour and CO2 , can absorb some of the Earth's emitted IR radiation and trap it in the atmosphere to provide an atmospheric greenhouse effect that currently adds about 38 K to the Earth's mean surface temperature. The associated greenhouse gas (GHG) and water cycles are a complex balance of interactions among surface ecosystems and atmospheric processes. The natural water and carbon cycles are being measurably disrupted by anthropogenic activities. Since the industrial revolution, significant anthropogenic sources of greenhouse gases and aerosols have evolved, while natural sinks, such as forests and wetlands, are being destroyed. Changes in the land cover affect the balance of GHG sources and sinks, as well as the Albedo and resultant surface temperature. Water vapour, the most abundant GHG, is affected indirectly though the influence of aerosols on cloud formation and precipitation patterns, and directly through the influence of surface temperatures on the water evaporation rates. There is also positive feedback between the water and carbon cycles. For example, drought can result in desertification with subsequent release of stored carbon. It is clear that the common thread in all of these climate-related effects is the interaction between the surface ecosystems and the carbonand nitrogen-containing gases in the lower troposphere. Uptake of CO2 by growing vegetation, release of CH4 and N2 O by soil processes, and the effects of carbon and water cycle chemistry all interact strongly in a system that is both ex-tremely complex and poorly understood at the present time. In order to quantify these processes and provide a clearer prediction of their likely effects in the

  9. 300 W-level, wavelength-widely-tunable, all-fiber integrated thulium-doped fiber laser.

    PubMed

    Yin, Ke; Zhu, Rongzhen; Zhang, Bin; Liu, Guangchen; Zhou, Pu; Hou, Jing

    2016-05-16

    A high-power, wavelength-tunable, all-fiber integrated thulium-doped fiber laser (TDFL) at 2 μm is presented. The TDFL has a compact configuration which only consists of a low power seed oscillator and a stage of fiber power amplifier. The seed oscillator adopts a tunable band-pass filter as the wavelength selective element, matching the gain spectrum of thulium-doped fiber. It can provide ~5 W single-mode seed laser with superb spectral characteristics, and the lasing wavelength is adjustable from 1890 to 2050 nm. The fiber power amplifier provides a total gain of ~17 dB at 2 μm which boosts the signal power to the 300 W-level. The maximum average power reaches 327.5 W at 1930 nm with the highest slope efficiency of 57.4%. This TDFL can afford >270 W lasing operation over the whole tuning range of 140 nm spanning from 1910 to 2050 nm, together with high spectral quality and power stability. This is the first demonstration, to the best of our knowledge, on an all-fiber integrated wavelength-widely-tunable TDFL at 2 μm with output power at the 300 W-level. The results are of great interest for many applications. PMID:27409931

  10. An Integrated Approach to Modeling Solar Electric Propulsion Vehicles During Long Duration, Near-Earth Orbit Transfers

    NASA Technical Reports Server (NTRS)

    Smith, David A.; Hojnicki, Jeffrey S.; Sjauw, Waldy K.

    2014-01-01

    Recent NASA interest in utilizing solar electronic propulsion (SEP) technology to transfer payloads, e.g. from low-Earth orbit (LEO) to higher energy geostationary-Earth orbit (GEO) or to Earth escape, has necessitated the development of high fidelity SEP vehicle models and simulations. These models and simulations need to be capable of capturing vehicle dynamics and sub-system interactions experienced during the transfer trajectories which are typically accomplished with continuous-burn (potentially interrupted by solar eclipse), long duration "spiral out" maneuvers taking several months or more to complete. This paper presents details of an integrated simulation approach achieved by combining a high fidelity vehicle simulation code with a detailed solar array model. The combined simulation tool gives researchers the functionality to study the integrated effects of various vehicle sub-systems (e.g. vehicle guidance, navigation and control (GN&C), electric propulsion system (EP)) with time varying power production. Results from a simulation model of a vehicle with a 50 kW class SEP system using the integrated tool are presented and compared to the results from another simulation model employing a 50 kW end-of-life (EOL) fixed power level assumption. These models simulate a vehicle under three degree of freedom dynamics (i.e. translational dynamics only) and include the effects of a targeting guidance algorithm (providing a "near optimal" transfer) during a LEO to near Earth escape (C (sub 3) = -2.0 km (sup 2) / sec (sup -2) spiral trajectory. The presented results include the impact of the fully integrated, time-varying solar array model (e.g. cumulative array degradation from traversing the Van Allen belts, impact of solar eclipses on the vehicle and the related temperature responses in the solar arrays due to operating in the Earth's thermal environment, high fidelity array power module, etc.); these are used to assess the impact on vehicle performance (i

  11. Nanocrystalline semiconductor doped rare earth oxide for the photocatalytic degradation studies on Acid Blue 113: A di-azo compound under UV slurry photoreactor.

    PubMed

    Suganya Josephine, G A; Mary Nisha, U; Meenakshi, G; Sivasamy, A

    2015-11-01

    Preventive measures for the control of environmental pollution and its remediation has received much interest in recent years due to the world-wide increase in the contamination of water bodies. Contributions of these harmful effluents are caused by the leather processing, pharmaceutical, cosmetic, textile, agricultural and other chemical industries. Nowadays, advanced oxidation processes considered to be better option for the complete destruction of organic contaminants in water and wastewater. Acid Blue 113 is a most widely used di-azo compound in leather, textile, dying and food industry as a color rending compound. In the present study, we have reported the photo catalytic degradation of Acid Blue 113 using a nanocrystalline semiconductor doped rare earth oxide as a photo catalyst under UV light irradiation. The photocatalyst was prepared by a simple precipitation technique and were characterized by XRD, FT-IR, UV-DRS and FE-SEM analysis. The experimental results proved that the prepared photo catalyst was nanocrystalline and highly active in the UV region. The UV-DRS results showed the band gap energy was 3.15eV for the prepared photo catalyst. The photodegradation efficiency was analyzed by various experimental parameters such as pH, catalyst dosage, variation of substrate concentration and effect of electrolyte addition. The photo degradation process followed a pseudo first order kinetics and was continuously monitored by UV-visible spectrophotometer. The experimental results proved the efficacy of the nanocrystalline zinc oxide doped dysprosium oxide which are highly active under UV light irradiations. It is also suggested that the prepared material would find wider applications in environmental remediation technologies to remove the carcinogenic and toxic moieties present in the industrial effluents.

  12. Nanocrystalline semiconductor doped rare earth oxide for the photocatalytic degradation studies on Acid Blue 113: A di-azo compound under UV slurry photoreactor.

    PubMed

    Suganya Josephine, G A; Mary Nisha, U; Meenakshi, G; Sivasamy, A

    2015-11-01

    Preventive measures for the control of environmental pollution and its remediation has received much interest in recent years due to the world-wide increase in the contamination of water bodies. Contributions of these harmful effluents are caused by the leather processing, pharmaceutical, cosmetic, textile, agricultural and other chemical industries. Nowadays, advanced oxidation processes considered to be better option for the complete destruction of organic contaminants in water and wastewater. Acid Blue 113 is a most widely used di-azo compound in leather, textile, dying and food industry as a color rending compound. In the present study, we have reported the photo catalytic degradation of Acid Blue 113 using a nanocrystalline semiconductor doped rare earth oxide as a photo catalyst under UV light irradiation. The photocatalyst was prepared by a simple precipitation technique and were characterized by XRD, FT-IR, UV-DRS and FE-SEM analysis. The experimental results proved that the prepared photo catalyst was nanocrystalline and highly active in the UV region. The UV-DRS results showed the band gap energy was 3.15eV for the prepared photo catalyst. The photodegradation efficiency was analyzed by various experimental parameters such as pH, catalyst dosage, variation of substrate concentration and effect of electrolyte addition. The photo degradation process followed a pseudo first order kinetics and was continuously monitored by UV-visible spectrophotometer. The experimental results proved the efficacy of the nanocrystalline zinc oxide doped dysprosium oxide which are highly active under UV light irradiations. It is also suggested that the prepared material would find wider applications in environmental remediation technologies to remove the carcinogenic and toxic moieties present in the industrial effluents. PMID:26025644

  13. Ultrathin Ca-PO4-CO3 solid-solution nanowires: a controllable synthesis and full-color emission by rare-earth doping.

    PubMed

    Hui, Junfeng; Yu, Qiyu; Long, Yong; Zhang, Zhicheng; Yang, Yong; Wang, Pengpeng; Xu, Biao; Wang, Xun

    2012-10-22

    It was found that calcium carbonate (CaCO(3)) and hydroxyapatite (Ca(10)(OH)(2)(PO(4))(6)), which are two crucial constituents of the most abundant minerals in nature and very important bioinorganic components in the tissues of mineralizing organisms, can form solid solutions in a wide range of PO(4)(3-)/CO(3)(2-) (P/C) ratios at low temperature when prepared as ultrathin nanowire structures. This is due to the special reactivity of ultrasmall nanocrystals, which can effectively lower the synthetic temperature and promote the formation of solid solutions. The as-prepared ultrathin nanowires with suitable P/C ratios presented strong blue luminescence due to the existence of abundant defects strengthened by CO(3)(2-). If used as the matrix, the as-prepared ultrathin nanowires demonstrated bright green or red luminescent properties when doped with Tb(3+) or Eu(3+) ions, and simultaneously retained their original morphologies. These three kinds of fluorescent nanowires could reproduce a full range of luminescence colors based on additive color mixtures of the three primary colors (red, green, and blue). In addition, under the same reaction system, ultrafine rare-earth-doped (Ce(3+), Tb(3+), Eu(3+)) nanowires (about 1 nm in diameter) were synthesized by using a one-step hydrothermal process, which further pushed the size of the Ca-PO(4)-CO(3) nanobuilding blocks to one unit cell region. These ultrafine nanowires displayed excellent film-forming properties and the ability to absorb UV radiation.

  14. Integrated oxygen-doping and dye sensitization of graphitic carbon nitride for enhanced visible light photodegradation.

    PubMed

    Liu, Shizhen; Sun, Hongqi; Ang, H M; Tade, Moses O; Wang, Shaobin

    2016-08-15

    Graphitic carbon nitride (GCN) is a promising metal-free photocatalyst while suffering from low charge mobility induced inefficient photocatalysis. In this work, oxygen doping was employed to enhance the photodegradation of organic pollutants in water on graphitic carbon nitride (GCNO) under visible light. For further absorption extension, four organic dyes (Eosin-Y, Perylene, Nile-red and Coumarin) were adopted to dye-sensitize the GCNO photocatalyst. It was found that O-doping can promote dye sensitization, which was dependent on the type of dyes and influenced the photodegradation efficiencies of methylene blue (MB) and phenol. Nile-red sensitized GCNO presented the best activity in MB degradation under λ>480nm irradiations while Eosin-Y showed the best sensitization performance for phenol degradation under λ>420nm light source. However, dye sensitization was not effective for enhanced pollutant degradation on GCN without O-doping. UV-vis diffuse reflectance spectra (UV-vis DRS), photoluminescence (PL) spectra, and photocurrent analyses were applied to investigate the mechanism of carriers' transfer, which indicated that dye molecules could inject extra electrons into GCNO energy band and the energy dislocation could suppress electron/hole recombination, enhancing photocatalytic performances.

  15. Superconductivity by rare earth doping in the 1038-type compounds (Ca1-xREx) 10(FeAs)10(Pt3As8) with RE=Y, La-Nd, Sm-Lu

    NASA Astrophysics Data System (ADS)

    Stürzer, Tobias; Derondeau, Gerald; Bertschler, Eva-Maria; Johrendt, Dirk

    2015-01-01

    We report superconductivity in polycrystalline samples of the 1038-type compounds (Ca1-xREx) 10(FeAs)10(Pt3As8) up to Tc=35 K with RE=Y, La-Nd, Sm, Gd-Lu. The critical temperatures are nearly independent of the trivalent rare earth element used, yielding a common Tc(xRE) phase diagram for electron doping in all these systems. The absence of superconductivity in Eu2+ doped samples, as well as the close resemblance of (Ca1-xREx) 10(FeAs)10(Pt3As8) to the 1048 compound substantiate that the electron doping scenario in the RE-1038 and 1048 phases is analogous to other iron-based superconductors with simpler crystal structures.

  16. Incorporating Stakeholder Decision Support Needs into an Integrated Regional Earth System Model

    SciTech Connect

    Rice, Jennie S.; Moss, Richard H.; Runci, Paul J.; Anderson, K. L.; Malone, Elizabeth L.

    2012-03-21

    A new modeling effort exploring the opportunities, constraints, and interactions between mitigation and adaptation at regional scale is utilizing stakeholder engagement in an innovative approach to guide model development and demonstration, including uncertainty characterization, to effectively inform regional decision making. This project, the integrated Regional Earth System Model (iRESM), employs structured stakeholder interactions and literature reviews to identify the most relevant adaptation and mitigation alternatives and decision criteria for each regional application of the framework. The information is used to identify important model capabilities and to provide a focus for numerical experiments. This paper presents the stakeholder research results from the first iRESM pilot region. The pilot region includes the Great Lakes Basin in the Midwest portion of the United States as well as other contiguous states. This geographic area (14 states in total) permits cohesive modeling of hydrologic systems while also providing gradients in climate, demography, land cover/land use, and energy supply and demand. The results from the stakeholder research indicate that iRESM should prioritize addressing adaptation alternatives in the water resources, urban infrastructure, and agriculture sectors, such as water conservation, expanded water quality monitoring, altered reservoir releases, lowered water intakes, urban infrastructure upgrades, increased electric power reserves in urban areas, and land use management/crop selection changes. Regarding mitigation alternatives, the stakeholder research shows a need for iRESM to focus on policies affecting the penetration of renewable energy technologies, and the costs and effectiveness of energy efficiency, bioenergy production, wind energy, and carbon capture and sequestration.

  17. Carbon Observations from Geostationary Earth Orbit as Part of an Integrated Observing System for Atmospheric Composition

    NASA Astrophysics Data System (ADS)

    Edwards, D. P.

    2015-12-01

    This presentation describes proposed satellite carbon measurements from the CHRONOS mission. The primary goal of this experiment is to measure the atmospheric pollutants carbon monoxide (CO) and methane (CH4) from geostationary orbit, with hourly observations of North America at high spatial resolution. CHRONOS observations would provide measurements not currently available or planned as part of a surface, suborbital and satellite integrated observing system for atmospheric composition over North America. Carbon monoxide is produced by combustion processes such as urban activity and wildfires, and serves as a proxy for other combustion pollutants that are not easily measured. Methane has diverse anthropogenic sources ranging from fossil fuel production, animal husbandry, agriculture and waste management. The impact of gas exploration in the Western States of the USA and oil extraction from the Canadian tar sands will be particular foci of the mission, as will the poorly-quantified natural CH4 emissions from wetlands and thawing permafrost. In addition to characterizing pollutant sources, improved understanding of the domestic CH4 budget is a priority for policy decisions related to short-lived climate forcers. A primary motivation for targeting CO is its value as a tracer of atmospheric pollution, and CHRONOS measurements will provide insight into local and long-range transport across the North American continent, as well as the processes governing the entrainment and venting of pollution in and out of the planetary boundary layer. As a result of significantly improved characterization of diurnal changes in atmospheric composition, CHRONOS observations will find direct societal applications for air quality regulation and forecasting. We present a quantification of this expected improvement in the prediction of near-surface concentrations when CHRONOS measurements are used in Observation System Simulation Experiments (OSSEs). If CHRONOS and the planned NASA Earth

  18. Thermochemical compatibility between selected (La,Sr)(Co,Fe,Ni)O 3 cathodes and rare earth doped ceria electrolytes

    NASA Astrophysics Data System (ADS)

    Zając, Wojciech; Świerczek, Konrad; Molenda, Janina

    In this paper the results of thermal expansion coefficient measurements of different singly and doubly doped ceria electrolytes, together with results for selected cathode materials from (La,Sr)(Co,Fe,Ni)O 3 system are given. A high temperature chemical stability of the cathode-electrolyte interface was measured on 1:1 wt. mixtures of previously characterized ceria and perovskite powders. The samples were heated at 800, 1000 or at 1200 °C in air for 6 or 100 h. Chemical reactivity investigations were conducted using XRD with Rietveld analysis. For all heated samples the crystal structure of both components were preserved. However, their lattice parameters evolved to a different extent, suggesting the existence of cation exchange. A formation of the solid state solution between Ce 1- xRE xO 2- x/2 and La(Co,Fe,Ni)O 3- δ was found, with mobile La cation. On the basis of the obtained results a qualitative mechanism of the observed reaction was proposed.

  19. Gamma ray spectroscopy employing divalent europium-doped alkaline earth halides and digital readout for accurate histogramming

    DOEpatents

    Cherepy, Nerine Jane; Payne, Stephen Anthony; Drury, Owen B.; Sturm, Benjamin W.

    2016-02-09

    According to one embodiment, a scintillator radiation detector system includes a scintillator, and a processing device for processing pulse traces corresponding to light pulses from the scintillator, where the processing device is configured to: process each pulse trace over at least two temporal windows and to use pulse digitization to improve energy resolution of the system. According to another embodiment, a scintillator radiation detector system includes a processing device configured to: fit digitized scintillation waveforms to an algorithm, perform a direct integration of fit parameters, process multiple integration windows for each digitized scintillation waveform to determine a correction factor, and apply the correction factor to each digitized scintillation waveform.

  20. An integrated study of earth resources in the state of California using remote sensing techniques. [water and forest management

    NASA Technical Reports Server (NTRS)

    Colwell, R. N.

    1974-01-01

    Progress and results of an integrated study of California's water resources are discussed. The investigation concerns itself primarily with the usefulness of remote sensing of relation to two categories of problems: (1) water supply; and (2) water demand. Also considered are its applicability to forest management and timber inventory. The cost effectiveness and utility of remote sensors such as the Earth Resources Technology Satellite for water and timber management are presented.

  1. High contrast in vivo bioimaging using multiphoton upconversion in novel rare-earth-doped fluoride upconversion nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Guanying; Yang, Chunhui; Prasad, Paras N.

    2013-02-01

    Upconversion in rare-earth ions is a sequential multiphoton process that efficiently converts two or more low-energy photons, which are generally near infrared (NIR) light, to produce anti-Stokes emission of a higher energy photon (e.g., NIR, visible, ultraviolet) using continuous-wave (cw) diode laser excitation. Here, we show the engineering of novel, efficient, and biocompatible NIRin-to-NIRout upconversion nanoparticles for biomedical imaging with both excitation and emission being within the "optical transparency window" of tissues. The small animal whole-body imaging with exceptional contrast (signal-to-noise ratio of 310) was shown using BALB/c mice intravenously injected with aqueously dispersed nanoparticles. An imaging depth as deep as 3.2-cm was successfully demonstrated using thick animal tissue (pork) under cw laser excitation at 980 nm.

  2. Multicolor and near-infrared electroluminescence from the light-emitting devices with rare-earth doped TiO{sub 2} films

    SciTech Connect

    Zhu, Chen; Gao, Zhifei; Wang, Canxing; Li, Dongsheng; Ma, Xiangyang Yang, Deren; Lv, Chunyan

    2015-09-28

    We report on multicolor and near-infrared electroluminescence (EL) from the devices using rare-earth doped TiO{sub 2} (TiO{sub 2}:RE) films as light-emitting layers, which are ascribed to the impact excitation of RE{sup 3+} ions, with the EL onset voltages below 10 V. The devices are in the structure of ITO/TiO{sub 2}:RE/SiO{sub 2}/Si, in which the SiO{sub 2} layer is ∼10 nm thick and RE includes Eu, Er, Tm, Nd, and so on. With sufficiently high positive voltage applied on the ITO electrode, the conduction electrons in Si can tunnel into the conduction band of SiO{sub 2} layer via the trap-assisted tunneling mechanism, gaining the potential energy ∼4 eV higher than the conduction band edge of TiO{sub 2}. Therefore, as the electrons in the SiO{sub 2} layer drift into the TiO{sub 2}:RE layer, they become hot electrons. Such hot electrons impact-excite the RE{sup 3+} ions incorporated into the TiO{sub 2} host, leading to the characteristic emissions.

  3. Furnace Cyclic Behavior of Plasma-Sprayed Zirconia-Yttria and Multi-Component Rare Earth Oxide Doped Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Nesbitt, James A.; McCue, Terry R.; Barrett, Charles A.; Miller, Robert A.

    2002-01-01

    Ceramic thermal barrier coatings will play an increasingly important role in advanced gas turbine engines because of their ability to enable further increases in engine temperatures. However, the coating performance and durability become a major concern under the increasingly harsh thermal cycling conditions. Advanced zirconia- and hafnia-based cluster oxide thermal barrier coatings with lower thermal conductivity and improved thermal stability are being developed using a high-heat-flux laser-rig based test approach. Although the new composition coatings were not yet optimized for cyclic durability, an initial durability screening of numerous candidate coating materials was carried out using conventional furnace cyclic tests. In this paper, furnace thermal cyclic behavior of the advanced plasma-sprayed zirconia-yttria-based thermal barrier coatings that were co-doped with multi-component rare earth oxides was investigated at 1163 C using 45 min hot cycles. The ceramic coating failure mechanisms were studied by using scanning electron microscopy combined with X-ray diffraction phase analysis after the furnace tests. The coating cyclic lifetime will be discussed in relation to coating phase structures, total dopant concentrations, and other properties.

  4. X-ray absorption spectroscopic analyses and fluorescence emission characteristics of PbO-Bi203-Ga203 glasses doped with rare-earth ions

    NASA Astrophysics Data System (ADS)

    Choi, Yong Gyu; Kim, Kyong-Hon; Chernov, Vladimir A.; Heo, Jong

    1999-12-01

    A representative of heavy metal oxide glasses, i.e., a PbO- Bi2O3-Ga2O3 glass, was investigated to identify the network structure of the glass and the electronic transition properties of rare-earth ions doped. X-ray absorption spectroscopic analyses showed that gallium forms GaO4 tetrahedral units with an average Ga-O bond length of approximately 1.87 A. Lead forms both PbO3 and PbO4 polyhedra, but the fraction of PbO4 decreases with decreasing PbO content. Bismuth in glasses constructs BiO5 and BiO6 polyhedra, which have a similar coordination scheme of the (alpha) -Bi2O3 crystal. Formation of three-coordinated oxygens is necessary to compensate shortage of oxygens to be two-fold coordinated. These glasses exhibit a relatively good thermal stability as well as the lowest phonon energy among oxide glasses, and thereby enhance numerous fluorescence emissions that are quenched in the conventional oxide glasses. Magnitudes of multiphonon relaxation are the lowest among oxide glasses and comparable to those of fluoride glasses. Fluorescence emission characteristics of Pr3+: 1.3 micrometer and Er3+: 2.7 micrometer were discussed in detail. In addition, influence of OH- on the Nd3+: 1.3 micrometer emission was analyzed. Further research efforts on impurity minimization and fiberization may realize a new oxide-based fiber-optic host.

  5. [Study on self-propagating synthesis of the doped SrAl2O4 rare earth long afterglow phosphors].

    PubMed

    Li, Yuan; Zhao, Yong-Liang; Liu, Yong-Gang; Wei, Xiao-Yan; Ren, Yue

    2011-06-01

    Twenty one doped SrAl2O4 long after-glowed phosphors with 4 series were synthesized by self-propagating high-temperature synthesis method (SHS) with urea-nitrate solution which served as media at 600 degrees C. They are SrAl2O4: Eu(2+)0.012 5, RE(3+)0.012 5 (RE(3+) = Ce(3+), Pr(3+), Nd(3+), Tb(3+), Dy(3+)), SrAl2O4 : Eu(2+)0.012 5, M0.012 5 (M = Li(+), Be(2+), Cd(2+), Mn(2+), Cu(2+), Ag(+), Zn(2+), Pb(2+)), SrAl2O4 : Eu(2+)0.012 5, Dy(3+)0.012 5, M0.012 5 (M = Mn(2+), Cu(2+), Ag(+), Zn(2+)), and SrAlO4 = Eu(2+)0.012 5, Dy(3+)0.012 5, RE(3+)0.012 5 (RE(3+) = Ce(3+), Pr(3+), Nd(3+), Tb(3+)), of which luminescence and after-glowing features were tested. The morphology of all these samples presents a state of porosity and laxity. The samples show an intense emission peak at 514 nm and broad peaks of the excitation spectra at 290-360 nm, Tb(3+) and Dy(3+) had most effects on luminance and after-glowed time respectively. The SrAl2O4 : Eu(2+)0.012 5, Dy(3+)0.012 5 had good luminance and proper after-glowed time as well.

  6. The Svalbard Integrated Arctic Earth Observing System (SIOS) ESFRI Initiative - A possible future cornerstone of European Arctic research

    NASA Astrophysics Data System (ADS)

    Hansen, Georg H.; Refsnes, Karin

    2010-05-01

    The Norwegian initiative "Svalbard Integrated Arctic Earth Observing System (SIOS) was included in the Revised Roadmap of the European Strategy Forum on Research Infrastructures (ESFRI) in 2009; an application to perform a preparatory phase project is currently under evaluation. The main aim of the SIOS initiative is to establish an Earth System observation platform in the European Arctic that is capable to match the whole scope of Earth System Models (ESM) on the observational side, ranging from solar/space-terrestrial interaction via atmosphere-ocean land-cryosphere coupling at the ground to geosphere-biosphere coupling. To this end, it is planned to integrate and upgrade all Arctic research stations on- and offshore in the Svalbard region which are currently operated by 15 nations, both European and worldwide. The initiative will also include the comprehensive marine and airborne monitoring and research activities and utilize the easy access to remote sensing data emerging from the satellite receiving activities at Longyearbyen. The already very comprehensive activity - though with limited international coordination - on Svalbard preconditions, as a first step, a thorough gap analysis of existing infrastructure in light of the needs of the modeling community and a careful design of the future overarching infrastructure. The interdisciplinary scientific character of SIOS makes the initiative well-suited to serve as a catalyser and integrator of the environmental ESFRI initiatives in the Arctic, while the truly global composition of the consortium may serve as a model for the envisaged pan-Arctic observing system SAON.

  7. Integrated microfluidic flowmeter based on a micro-FBG inscribed in Co²⁺-doped optical fiber.

    PubMed

    Liu, Zhengyong; Tse, Ming-Leung Vincent; Zhang, A Ping; Tam, Hwa-Yaw

    2014-10-15

    A novel microfluidic flowmeter integrated with microfiber Bragg grating (µFBG) is presented. Two glass capillaries and a short length of high-light-absorption Co²⁺-doped optical fiber were stacked inside a larger outer capillary tube. The stack was then drawn into a tapered device. Two microchannels with the diameter of ~50  μm were formed inside the capillaries for flowing of microfluidics. An FBG was inscribed in the tapered Co²⁺-doped fiber with waist diameter of ~70  μm, and acts as a flow-rate sensor. A pump laser with wavelength of 1480 nm was utilized to locally heat the µFBG, rendering the µFBG as miniature "hot-wire" flowmeter. The flow rate of the liquid in the microchannels is determined by the induced wavelength shift of the µFBG. The experimental results achieve a minimum detectable change of ~16  nL/s in flow rate, which is very promising in the use as part of biochips.

  8. Integrated cladding-pumped multicore few-mode erbium-doped fibre amplifier for space-division-multiplexed communications

    NASA Astrophysics Data System (ADS)

    Chen, H.; Jin, C.; Huang, B.; Fontaine, N. K.; Ryf, R.; Shang, K.; Grégoire, N.; Morency, S.; Essiambre, R.-J.; Li, G.; Messaddeq, Y.; Larochelle, S.

    2016-08-01

    Space-division multiplexing (SDM), whereby multiple spatial channels in multimode and multicore optical fibres are used to increase the total transmission capacity per fibre, is being investigated to avert a data capacity crunch and reduce the cost per transmitted bit. With the number of channels employed in SDM transmission experiments continuing to rise, there is a requirement for integrated SDM components that are scalable. Here, we demonstrate a cladding-pumped SDM erbium-doped fibre amplifier (EDFA) that consists of six uncoupled multimode erbium-doped cores. Each core supports three spatial modes, which enables the EDFA to amplify a total of 18 spatial channels (six cores × three modes) simultaneously with a single pump diode and a complexity similar to a single-mode EDFA. The amplifier delivers >20 dBm total output power per core and <7 dB noise figure over the C-band. This cladding-pumped EDFA enables combined space-division and wavelength-division multiplexed transmission over multiple multimode fibre spans.

  9. Gamma ray spectroscopy employing divalent europium-doped alkaline earth halides and digital readout for accurate histogramming

    DOEpatents

    Cherepy, Nerine Jane; Payne, Stephen Anthony; Drury, Owen B; Sturm, Benjamin W

    2014-11-11

    A scintillator radiation detector system according to one embodiment includes a scintillator; and a processing device for processing pulse traces corresponding to light pulses from the scintillator, wherein pulse digitization is used to improve energy resolution of the system. A scintillator radiation detector system according to another embodiment includes a processing device for fitting digitized scintillation waveforms to an algorithm based on identifying rise and decay times and performing a direct integration of fit parameters. A method according to yet another embodiment includes processing pulse traces corresponding to light pulses from a scintillator, wherein pulse digitization is used to improve energy resolution of the system. A method in a further embodiment includes fitting digitized scintillation waveforms to an algorithm based on identifying rise and decay times; and performing a direct integration of fit parameters. Additional systems and methods are also presented.

  10. Space-Based Sensor Web for Earth Science Applications: An Integrated Architecture for Providing Societal Benefits

    NASA Technical Reports Server (NTRS)

    Habib, Shahid; Talabac, Stephen J.

    2004-01-01

    There is a significant interest in the Earth Science research and user remote sensing community to substantially increase the number of useful observations relative to the current frequency of collection. The obvious reason for such a push is to improve the temporal, spectral, and spatial coverage of the area(s) under investigation. However, there is little analysis available in terms of the benefits, costs and the optimal set of sensors needed to make the necessary observations. Classic observing system solutions may no longer be applicable because of their point design philosophy. Instead, a new intelligent data collection system paradigm employing both reactive and proactive measurement strategies with adaptability to the dynamics of the phenomena should be developed. This is a complex problem that should be carefully studied and balanced across various boundaries including: science, modeling, applications, and technology. Modeling plays a crucial role in making useful predictions about naturally occurring or human-induced phenomena In particular, modeling can serve to mitigate the potentially deleterious impacts a phenomenon may have on human life, property, and the economy. This is especially significant when one is interested in learning about the dynamics of, for example, the spread of forest fires, regional to large-scale air quality issues, the spread of the harmful invasive species, or the atmospheric transport of volcanic plumes and ash. This paper identifies and examines these challenging issues and presents architectural alternatives for an integrated sensor web to provide observing scenarios driving the requisite dynamic spatial, spectral, and temporal characteristics to address these key application areas. A special emphasis is placed on the observing systems and its operational aspects in serving the multiple users and stakeholders in providing societal benefits. We also address how such systems will take advantage of technological advancement in

  11. Empowering Rural Appalachian Youth Through Integrated Inquiry-based Earth Science

    NASA Astrophysics Data System (ADS)

    Cartwright, T. J.; Hogsett, M.

    2009-05-01

    Science education must be relevant and inspiring to keep students engaged and receptive to learning. Reports suggest that science education reform can be advanced by involving students in active research (NSF 1996). Through a 2-year Geoscience Education award from the National Science Foundation, a program called IDGE (Integrated Design for Geoscience Education) has targeted low-income, under-represented, and minority high school students in rural Appalachia in inquiry-based projects, international collaboration, and an international environmental expedition incorporating the GLOBE program protocols. This program targeted Upward Bound students at Marshall University in Huntington, West Virginia. The Upward Bound is a federally-supported program targeting low-income, under-represented, and minority students for inclusion in a summer academic- enrichment program. IDGE builds on the mission of Upward Bound by encouraging underprivileged students to investigate science and scientific careers. This outreach has proven to be successful in enhancing positive attitudes and understanding about science and increasing the number of students considering science careers. IDGE has found that students must be challenged to observe the world around them and to consider how their decisions affect the future of our planet, thus making geoscience relevant and interesting to the students. By making the geoscience course inquiry-based and incorporating field research that is relevant to local environmental issues, it becomes possible for students to bridge the gap between science in theory and science in practice while remaining engaged. Participants were able to broaden environmental connections through an ecological expedition experience to Costa Rica, serving as an opportunity to broaden the vision of students as members of an international community of learners and scientists through their experiences with a diverse natural environment. This trip, in coordination with the inclusion

  12. Laboratory Earth Under the Lens: Diachronic Evaluation of an Integrated Graduate-Level On-Line Earth System Science Course Series for K-12 Educators

    NASA Astrophysics Data System (ADS)

    Low, R.; Gosselin, D. C.; Haney, C.; Larson-Miller, C.; Bonnstetter, R.; Mandryk, C.

    2012-12-01

    Educational research strives to identify the pedagogies that promote student learning. However, the body of research identifying the characteristics of effective teacher preparation is "least strong for science," and is largely based on studies of the effectiveness of individual courses or workshops (NRC 2010). The National Research Council's "Preparing Teachers: Building Evidence for Strong Policy," (2010) provides a mandate for teacher education providers to conduct research on program-scale effectiveness. The high priority research agenda identified by the NRC is expected to elicit understanding of the aspects of teacher preparation that critically impact classroom student learning outcomes. The Laboratory Lens project is designed to identify effective practices in a teacher education program, with specific reference to the content domain of Earth science. Now in its fifth year, the Masters of Applied Science (MAS) program at UNL offers a variety of science courses, ranging from entomology to food science. The six-course Lab Earth series serves as the backbone of the Specialization for Science Educators within the MAS program, and provides comprehensive content coverage of all Earth science topics identified in the AAAS Benchmarks. "How People Learn," (NRC 2009) emphasizes that expert knowledge includes not only factual knowledge, but also the well-developed conceptual framework critical to the ability to, "remember, reason, and solve problems." A focus of our research is to document the process by which the transition from novice to expert takes place in Lab Earth's on-line teacher participants. A feature of our research design is the standardization of evaluation instruments across the six courses. We have used data derived from implementation of the Community of Inquiry Survey (COI) in pilot offerings to ensure that the course sequence is effective in developing a community of learners, while developing their content knowledge. A pre- and post- course

  13. Modeling Earth's Disk-Integrated, Time-Dependent Spectrum: Applications to Directly Imaged Habitable Planets

    NASA Astrophysics Data System (ADS)

    Lustig-Yaeger, Jacob; Schwieterman, Edward; Meadows, Victoria; Fujii, Yuka; NAI Virtual Planetary Laboratory, ISSI 'The Exo-Cartography Inverse Problem'

    2016-10-01

    Earth is our only example of a habitable world and is a critical reference point for potentially habitable exoplanets. While disk-averaged views of Earth that mimic exoplanet data can be obtained by interplanetary spacecraft, these datasets are often restricted in wavelength range, and are limited to the Earth phases and viewing geometries that the spacecraft can feasibly access. We can overcome these observational limitations using a sophisticated UV-MIR spectral model of Earth that has been validated against spacecraft observations in wavelength-dependent brightness and phase (Robinson et al., 2011; 2014). This model can be used to understand the information content – and the optimal means for extraction of that information – for multi-wavelength, time-dependent, disk-averaged observations of the Earth. In this work, we explore key telescope parameters and observing strategies that offer the greatest insight into the wavelength-, phase-, and rotationally-dependent variability of Earth as if it were an exoplanet. Using a generalized coronagraph instrument simulator (Robinson et al., 2016), we synthesize multi-band, time-series observations of the Earth that are consistent with large space-based telescope mission concepts, such as the Large UV/Optical/IR (LUVOIR) Surveyor. We present fits to this dataset that leverage the rotationally-induced variability to infer the number of large-scale planetary surface types, as well as their respective longitudinal distributions and broadband albedo spectra. Finally, we discuss the feasibility of using such methods to identify and map terrestrial exoplanets surfaces with the next generation of space-based telescopes.

  14. Core-Shell Co/CoO Integrated on 3D Nitrogen Doped Reduced Graphene Oxide Aerogel as an Enhanced Electrocatalyst for the Oxygen Reduction Reaction

    PubMed Central

    Wang, Meng; Hou, Yuyang; Slade, Robert C. T.; Wang, Jiazhao; Shi, Dongqi; Wexler, David; Liu, Huakun; Chen, Jun

    2016-01-01

    Here, we demonstrate that Cobalt/cobalt oxide core-shell nanoparticles integrated on nitrogen-doped (N-doped) three-dimensional reduced graphene oxide aerogel-based architecture (Co/CoO-NGA) were synthesized through a facile hydrothermal method followed by annealing treatment. The unique endurable porous structure could provide sufficient mass transfer channels and ample active sites on Co/CoO-NGA to facilitate the catalytic reaction. The synthesized Co/CoO-NGA was explored as an electrocatalyst for the oxygen reduction reaction, showing comparable oxygen reduction performance with excellent methanol resistance and better durability compared with Pt/C.

  15. Core-Shell Co/CoO Integrated on 3D Nitrogen Doped Reduced Graphene Oxide Aerogel as an Enhanced Electrocatalyst for the Oxygen Reduction Reaction

    PubMed Central

    Wang, Meng; Hou, Yuyang; Slade, Robert C. T.; Wang, Jiazhao; Shi, Dongqi; Wexler, David; Liu, Huakun; Chen, Jun

    2016-01-01

    Here, we demonstrate that Cobalt/cobalt oxide core-shell nanoparticles integrated on nitrogen-doped (N-doped) three-dimensional reduced graphene oxide aerogel-based architecture (Co/CoO-NGA) were synthesized through a facile hydrothermal method followed by annealing treatment. The unique endurable porous structure could provide sufficient mass transfer channels and ample active sites on Co/CoO-NGA to facilitate the catalytic reaction. The synthesized Co/CoO-NGA was explored as an electrocatalyst for the oxygen reduction reaction, showing comparable oxygen reduction performance with excellent methanol resistance and better durability compared with Pt/C. PMID:27597939

  16. Core-Shell Co/CoO Integrated on 3D Nitrogen Doped Reduced Graphene Oxide Aerogel as an Enhanced Electrocatalyst for the Oxygen Reduction Reaction.

    PubMed

    Wang, Meng; Hou, Yuyang; Slade, Robert C T; Wang, Jiazhao; Shi, Dongqi; Wexler, David; Liu, Huakun; Chen, Jun

    2016-01-01

    Here, we demonstrate that Cobalt/cobalt oxide core-shell nanoparticles integrated on nitrogen-doped (N-doped) three-dimensional reduced graphene oxide aerogel-based architecture (Co/CoO-NGA) were synthesized through a facile hydrothermal method followed by annealing treatment. The unique endurable porous structure could provide sufficient mass transfer channels and ample active sites on Co/CoO-NGA to facilitate the catalytic reaction. The synthesized Co/CoO-NGA was explored as an electrocatalyst for the oxygen reduction reaction, showing comparable oxygen reduction performance with excellent methanol resistance and better durability compared with Pt/C. PMID:27597939

  17. Core-Shell Co/CoO Integrated on 3D Nitrogen Doped Reduced Graphene Oxide Aerogel as an Enhanced Electrocatalyst for the Oxygen Reduction Reaction.

    PubMed

    Wang, Meng; Hou, Yuyang; Slade, Robert C T; Wang, Jiazhao; Shi, Dongqi; Wexler, David; Liu, Huakun; Chen, Jun

    2016-01-01

    Here, we demonstrate that Cobalt/cobalt oxide core-shell nanoparticles integrated on nitrogen-doped (N-doped) three-dimensional reduced graphene oxide aerogel-based architecture (Co/CoO-NGA) were synthesized through a facile hydrothermal method followed by annealing treatment. The unique endurable porous structure could provide sufficient mass transfer channels and ample active sites on Co/CoO-NGA to facilitate the catalytic reaction. The synthesized Co/CoO-NGA was explored as an electrocatalyst for the oxygen reduction reaction, showing comparable oxygen reduction performance with excellent methanol resistance and better durability compared with Pt/C.

  18. Continuous monitoring of a large active earth flow using an integrated GPS - automatic total station approach

    NASA Astrophysics Data System (ADS)

    Corsini, A.

    2009-04-01

    Landslide monitoring has evolved as a crucial tool in civil protection to mitigate and prevent disasters. The research presents an approach to continuous monitoring of a large-scale active earth flow using a system that integrates surface measurements obtained by a GPS and an automatic total station. With the data obtained from the system the landslide can be monitored in near-real-time and surface displacements can be directly utilized to provide early warning of slope movements and to study the behavior of the landslide, e.g. to predict timing and mechanisms of future failure. The Valoria landslide located in the northern Apennines of Italy was reactivated in 2001, 2005 and 2007 damaging roads and endangering houses. A monitoring system was installed in 2007-2008 in the frame of a civil protection plan aimed at risk mitigation. The system consists of an automatic total station measuring about 40 prisms located in the landslide to a maximum distance of 1.800 km; one double-frequency GPS receiver connects in streaming by wireless communication with 4 single-frequency GPS in side the flow. Until December 2007 the monitoring network was operated with periodic static surveying followed by the data post-processing. From September 2007 until March 2008 the landslide deformation was evaluated by periodic surveys with the total station and the GPS system. This first measure showed that the displacements were influenced by the rainfall events and by the snow melting. The total displacements measured vary from centimeter scale in the crown zone, where retrogressive movements were in progress, to over 50 m in the flow track zone. Starting in March 2008 data acquisition by the total station system and GPS were automated in order to allow continuous and near-real-time data processing. The displacement data collected in one and a half year of continuous operation show different acceleration and deceleration phases as a result of the pore water pressure distribution inside the

  19. Alkaline Earth Metal Zirconate Perovskites MZrO3 (M=Ba(2+), Sr(2+), Ca(2+)) Derived from Molecular Precursors and Doped with Eu(3+) Ions.

    PubMed

    Drąg-Jarząbek, Anna; John, Łukasz; Petrus, Rafał; Kosińska-Klähn, Magdalena; Sobota, Piotr

    2016-03-24

    The effect of alkaline earth metal alkoxides on the protonation of zirconocene dichloride was investigated. This approach enabled the design of compounds with preset molecular structures for generating high-purity binary metal oxide perovskites MZrO3 (M=Ba(2+), Sr(2+), Ca(2+)). Single-source molecular precursors [Ba4 Zr2 (μ6 -O)(μ3 ,η(2)-OR)8 (OR)2(η(2) -HOR)2 (HOR)2 Cl4], [Sr4 Zr2 (μ6 -O)(μ3 ,η(2)-OR)8 (OR)2 (HOR)4 Cl4], [Ca4 Zr2 (μ6-O)(μ3 ,η(2)-OR)8 (OR)2 Cl4], and [Ca6 Zr2 (μ2 ,η(2)-OR)12 (μ-Cl)2 (η(2) -HOR)4 Cl6 ]⋅8 CH2 Cl2 were prepared via elimination of the cyclopentadienyl ring from Cp2 ZrCl2 as CpH in the presence of M(OR)2 and alcohol ROH (ROH=CH3OCH2 CH2OH) as a source of protons. The resulting complexes were characterized by elemental analysis, IR and NMR spectroscopy, and single-crystal X-ray diffraction. The compounds were then thermally decomposed to MCl2 /MZrO3 mixtures. Leaching of MCl2 from the raw powder with deionized water produced highly pure perovskite-like oxide particles of 40-80 nm in size. Luminescence studies on Eu(3+)-doped MZrO3 revealed that the perovskites are attractive host lattices for potential applications in display technology. PMID:26891039

  20. Observations from Integrated Ground Motion Using EarthScope's USArray Transportable Array

    NASA Astrophysics Data System (ADS)

    West, J. D.; Fouch, M. J.

    2012-12-01

    Integrated Ground Motion (IGM) is a new method for visualizing and investigating long-term changes in seismic background levels. These new time series present an opportunity to evaluate variations in background seismic levels on intermediate time scales longer than those usually considered in processing seismic event data, but shorter than the time scales typically utilized when measuring the power spectral density (PSD) function of a seismic channel or instrument. Example uses for this new method include determining relationships between weather and seismic noise, detection of uncataloged small seismic and slow slip events, detection and characterization of remotely triggered seismicity, detection and monitoring of induced seismicity and detection of non-seismic signals. Here we apply the IGM processing method to broadband seismic data from the EarthScope USArray Transportable Array (TA) [www.usarray.org], and present some preliminary observations of the observed patterns in seismicity. We generate IGM time series from raw broadband seismic data by filtering and evaluating the envelope of a sliding time window. We further process the resulting IGM time series to remove peaks from short-duration seismic events by clipping the series at the 95th percentile value and normalizing each resulting series on a 0-1 scale. For this initial evaluation, we process IGM from overlapping 15-minute windows sampled every 5 minutes from four weeks of TA data for the western US in early 2008, bandpass filtering over four different ranges: 7-19 Hz, 1-8 Hz, 1-20 sec, and 20-100 sec. We create a series of animations overlaying the IGM values on a map of the western US and compressing the time scale to 2 hours/second. We observe that IGM in the 7-19 Hz and 1-8 Hz bands is primarily influenced by diurnal variations in background seismic levels, which generally overwhelm the signals from small (M<1.5) local earthquakes. Small earthquakes are somewhat more visible in the 1-8 Hz band. In

  1. CVT/GPL phase 2 integrated testing. [in earth observations, space physics, and material sciences

    NASA Technical Reports Server (NTRS)

    Shurney, R. E.; Maybee, G.; Schmitt, S.

    1974-01-01

    Experiments representing earth observations, space physics, and material sciences disciplines were installed in the General Purpose Laboratory (GPL). The experiments and the GPL are described. The experiments interfaces the GPL and GPL support systems are assessed. The experiments were cloud physics, ionospheric disturbances, material sciences, high energy astronomy, and superfluid helium.

  2. Learning in the Middle School Earth Science Classroom: Students Conceptually Integrate New Knowledge Using Intelligent Laserdiscs.

    ERIC Educational Resources Information Center

    Freitag, Patricia K.; Abegg, Gerald L.

    A study was designed to describe how middle school students select, link, and determine relationships between textual and visual information. Fourteen authoring groups were formed from both eighth-grade earth science classes of one veteran teacher in one school. Each group was challenged to produce an informative interactive laservideodisc project…

  3. "Space on Earth:" A Learning Community Integrating English, Math, and Science

    ERIC Educational Resources Information Center

    Fortna, Joanna; Sullivan, Jim

    2010-01-01

    Imagine a mathematics instructor and English instructor sharing an office; scribbled equations litter one desk, snatches of poetry the other. Our learning community, "Space on Earth," grew from conversations in just such an office where we bridged our own disciplinary gap and discovered a shared passion for helping students apply the concepts and…

  4. Integrating Undergraduate Research and Teaching in Environmental Education: Ohio State's Earth Day Project.

    ERIC Educational Resources Information Center

    Wright, Pamela A.; Floyd, Donald W.

    1992-01-01

    Presents the results of a survey administered by college students to the university community (n=313) as part of an earth week class project designed to merge research, teaching, and community outreach. Discusses the survey as a teaching tool, research, and community outreach program. (21 references) (MCO)

  5. Use of Persistent Identifiers to link Heterogeneous Data Systems in the Integrated Earth Data Applications (IEDA) Facility

    NASA Astrophysics Data System (ADS)

    Hsu, L.; Lehnert, K. A.; Carbotte, S. M.; Arko, R. A.; Ferrini, V.; O'hara, S. H.; Walker, J. D.

    2012-12-01

    The Integrated Earth Data Applications (IEDA) facility maintains multiple data systems with a wide range of solid earth data types from the marine, terrestrial, and polar environments. Examples of the different data types include syntheses of ultra-high resolution seafloor bathymetry collected on large collaborative cruises and analytical geochemistry measurements collected by single investigators in small, unique projects. These different data types have historically been channeled into separate, discipline-specific databases with search and retrieval tailored for the specific data type. However, a current major goal is to integrate data from different systems to allow interdisciplinary data discovery and scientific analysis. To increase discovery and access across these heterogeneous systems, IEDA employs several unique IDs, including sample IDs (International Geo Sample Number, IGSN), person IDs (GeoPass ID), funding award IDs (NSF Award Number), cruise IDs (from the Marine Geoscience Data System Expedition Metadata Catalog), dataset IDs (DOIs), and publication IDs (DOIs). These IDs allow linking of a sample registry (System for Earth SAmple Registration), data libraries and repositories (e.g. Geochemical Research Library, Marine Geoscience Data System), integrated synthesis databases (e.g. EarthChem Portal, PetDB), and investigator services (IEDA Data Compliance Tool). The linked systems allow efficient discovery of related data across different levels of granularity. In addition, IEDA data systems maintain links with several external data systems, including digital journal publishers. Links have been established between the EarthChem Portal and ScienceDirect through publication DOIs, returning sample-level objects and geochemical analyses for a particular publication. Linking IEDA-hosted data to digital publications with IGSNs at the sample level and with IEDA-allocated dataset DOIs are under development. As an example, an individual investigator could sign up

  6. Evaluating Depth-Integrated Steric Contributions to Sea-Level Trends and Variability in Earth System Model Ensembles

    NASA Astrophysics Data System (ADS)

    Hogan, E.; Sriver, R. L.

    2015-12-01

    Earth system model ensembles exhibit considerable uncertainties surrounding trends and magnitude of steric sea-level variations, due in part to structural model differences, internal model variability, and parameterizations that influence ocean heat uptake. Here we analyze depth-integrated steric sea-level changes using the CMIP5 models and a new CESM ensemble that samples internal variability of the coupled Earth system. The CESM ensemble contains 50 members, with historical and future projections (1850-2100) initialized from unique model states sampled from a ~10,000 year fully coupled unforced equilibrium simulation. The CESM ensemble enables us to examine how initial conditions uncertainty (internal variability) within the full-ocean can influence depth-integrated steric sea-level variability. The second ensemble is comprised of runs from 32 different CMIP5 models. We performed grid-level drift correction for each model using the pre-industrial control simulations, which enables us to examine depth-integrated variability and trends due to different model structures. We compare and contrast our results with published observational datasets, and we analyze the effect of different sources of uncertainty on simulated sea-level variability and trends for different ocean depths. Results point to the importance of the deep ocean in attempting to attribute and predict temporal patterns of steric sea-level on a global scale.

  7. Modeling the globally-integrated spectral variability of the Archean Earth: The purple planet

    NASA Astrophysics Data System (ADS)

    Palle, E.; Sanroma, E.; Parenteau, M. N.; Kiang, N. Y.; Gutierrez-Navarro, A. M.; Lopez, R.; Montañes-Rodríguez, P.

    2014-03-01

    Ongoing searches for exoplanetary systems have revealed a wealth of planets with diverse physical properties. Planets even smaller than the Earth have already been detected and the efforts of future missions are aimed at the discovery, and perhaps characterization, of small rocky exoplanets within the habitable zone of their stars. Clearly, what we know about our planet will be our guideline for the characterization of such planets. But the Earth has been inhabited for at least 3.8 Gyr and its appearance has changed with time. Here, we have studied the Earth during the Archean eon, 3 Gyr ago. At that time, one of the more widespread life forms on the planet were purple bacteria. These bacteria are photosynthetic microorganisms and can inhabit both aquatic and terrestrial environments. Here, we use a radiative transfer model to simulate the visible and near-infrared radiation reflected by our planet, taking into account several scenarios regarding the possible distribution of purple bacteria over continents and oceans. We find that purple bacteria have a reflectance spectrum that has a strong reflectivity increase, similar to the red edge of leafy plants, although shifted redward. This feature produces a detectable signal in the disk-averaged spectra of our planet, depending on cloud amount and bacteria concentration/ distribution. We conclude that by using multi-color photometric observations, it is possible to distinguish between an Archean Earth in which purple bacteria inhabit vast extensions of the planet and a present-day Earth with continents covered by deserts, vegetation, or microbial mats.

  8. Electrically tunable fiber-integrated Yb-doped laser covering 74 nm based on a fiber Bragg grating array

    NASA Astrophysics Data System (ADS)

    Tiess, T.; Rothhardt, M.; Chojetzki, C.; Jäger, M.; Bartelt, H.

    2015-03-01

    Fiber lasers provide the foundation to combine an excellent beam quality in single mode operation with a robust and highly efficient design. Based on fiber-integrated configurations, they are employed in many different applications ranging from industry over research to medical technology. However, there is lots of potential to approach even new fields of applications e.g. in spectroscopy based on tunable systems with an adjustable emission wavelength. We present a novel tuning concept for pulsed fiber-integrated laser systems using an array of fiber Bragg gratings (FBGs) as discrete spectral filter. Based on stacking many standard FBGs, the bandwidth and filter properties are easy to scale by increasing the number of gratings allowing huge tuning ranges as well as tailored tuning characteristics. In this work, we demonstrate the potential of this electrically controlled tuning concept. Using an Ytterbium (Yb)-doped fiber laser, we investigate the general tuning characteristics. With variable pulse durations in the nanosecond regime, we demonstrate high signal contrast (~45 dB), excellent wavelength stability and narrow linewidth (<15 GHz). In order to highlight the great spectral freedom, a tuning range of 74 nm in the Yb band is realized which, to the best of our knowledge, is the largest bandwidth reported based on a monolithic filter design.

  9. Monolithic integration of erbium-doped amplifiers with silicon-on-insulator waveguides.

    PubMed

    Agazzi, Laura; Bradley, Jonathan D B; Dijkstra, Meindert; Ay, Feridun; Roelkens, Gunther; Baets, Roel; Wörhoff, Kerstin; Pollnau, Markus

    2010-12-20

    Monolithic integration of Al2O3:Er3+ amplifier technology with passive silicon-on-insulator waveguides is demonstrated. A signal enhancement of >7 dB at 1533 nm wavelength is obtained. The straightforward wafer-scale fabrication process, which includes reactive co-sputtering and subsequent reactive ion etching, allows for parallel integration of multiple amplifier and laser sections with silicon or other photonic circuits on a chip.

  10. Sun-, Earth- and Moon-integrated simulation ray tracing for observation from space using ASAP

    NASA Astrophysics Data System (ADS)

    Breault, Robert P.; Kim, Sug-Whan; Yang, Seul-Ki; Ryu, Dongok

    2014-09-01

    The Space Optics Laboratory at Yonsei University, Korea, in cooperation with Breault Research Organization (BRO) in Tucson, Arizona, have invested significant research and development efforts into creating large scale ray tracing techniques for simulating "reflected" light from the earth with an artificial satellite. This presentation describes a complex model that combines the sun, the earth and an orbiting optical instrument combined into a real scale nonsequential ray tracing computation using BRO's Advanced Systems Analysis Program, ASAP®. The Sun is simulated as a spherically emitting light source of 695,500 km in diameter. The earth also is simulated as a sphere with its characteristics defined as target objects to be observed and defined with appropriate optical properties. They include the atmosphere, land and ocean elements, each having distinctive optical properties expressed by single or combined characteristics of refraction, reflection and scattering. The current embodiment has an atmospheric model consisting of 33 optical layers, a land model with 6 different albedos and the ocean simulated with sun glint characteristics. A space-based optical instrument, with an actual opto-mechanical prescription, is defined in an orbit of several hundreds to thousands of miles in altitude above the earth's surface. The model allows for almost simultaneous evaluations of the imaging and radiometric performances of the instrument. Several real-life application results are reported suggesting that this simulation approach not only provides valuable information that can greatly improve the space optical instrument performance but also provides a simulation tool for scientists to evaluate all phases of a space mission.

  11. Formation of an integrated holding company to produce rare-earth metal articles

    NASA Astrophysics Data System (ADS)

    Bogdanov, S. V.; Grishaev, S. I.

    2013-12-01

    The possibility of formation of a Russian holding company for the production of rare-earth metal articles under conditions of its increasing demand on the world market is considered. It is reasonable to ensure stable business operation on the market under conditions of state-private partnership after the fraction of soled products is determined and supported by the competitive advantages of Russian products.

  12. Semantic Data Integration and Ontology Use within the Global Earth Observation System of Systems (GEOSS) Global Water Cycle Data Integration System

    NASA Astrophysics Data System (ADS)

    Pozzi, W.; Fekete, B.; Piasecki, M.; McGuinness, D.; Fox, P.; Lawford, R.; Vorosmarty, C.; Houser, P.; Imam, B.

    2008-12-01

    The inadequacies of water cycle observations for monitoring long-term changes in the global water system, as well as their feedback into the climate system, poses a major constraint on sustainable development of water resources and improvement of water management practices. Hence, The Group on Earth Observations (GEO) has established Task WA-08-01, "Integration of in situ and satellite data for water cycle monitoring," an integrative initiative combining different types of satellite and in situ observations related to key variables of the water cycle with model outputs for improved accuracy and global coverage. This presentation proposes development of the Rapid, Integrated Monitoring System for the Water Cycle (Global-RIMS)--already employed by the GEO Global Terrestrial Network for Hydrology (GTN-H)--as either one of the main components or linked with the Asian system to constitute the modeling system of GEOSS for water cycle monitoring. We further propose expanded, augmented capability to run multiple grids to embrace some of the heterogeneous methods and formats of the Earth Science, Hydrology, and Hydraulic Engineering communities. Different methodologies are employed by the Earth Science (land surface modeling), the Hydrological (GIS), and the Hydraulic Engineering Communities; with each community employing models that require different input data. Data will be routed as input variables to the models through web services, allowing satellite and in situ data to be integrated together within the modeling framework. Semantic data integration will provide the automation to enable this system to operate in near-real-time. Multiple data collections for ground water, precipitation, soil moisture satellite data, such as SMAP, and lake data will require multiple low level ontologies, and an upper level ontology will permit user-friendly water management knowledge to be synthesized. These ontologies will have to have overlapping terms mapped and linked together. so

  13. Integrated Earth Science Research in Deep Underground Science and Engineering Laboratories

    NASA Astrophysics Data System (ADS)

    Wang, J. S.; Hazen, T. C.; Conrad, M. E.; Johnson, L. R.; Salve, R.

    2004-12-01

    There are three types of sites being considered for deep-underground earth science and physics experiments: (1) abandoned mines (e.g., the Homestake Gold Mine, South Dakota; the Soudan Iron Mine, Minnesota), (2) active mines/facilities (e.g., the Henderson Molybdenum Mine, Colorado; the Kimballton Limestone Mine, Virginia; the Waste Isolation Pilot Plant [in salt], New Mexico), and (3) new tunnels (e.g., Icicle Creek in the Cascades, Washington; Mt. San Jacinto, California). Additional sites have been considered in the geologically unique region of southeastern California and southwestern Nevada, which has both very high mountain peaks and the lowest point in the United States (Death Valley). Telescope Peak (along the western border of Death Valley), Boundary Peak (along the California-Nevada border), Mt. Charleston (outside Las Vegas), and Mt. Tom (along the Pine Creek Valley) all have favorable characteristics for consideration. Telescope Peak can site the deepest laboratory in the United States. The Mt. Charleston tunnel can be a highway extension connecting Las Vegas to Pahrump. The Pine Creek Mine next to Mt. Tom is an abandoned tungsten mine. The lowest levels of the mine are accessible by nearly horizontal tunnels from portals in the mining base camp. Drainage (most noticeable in the springs resulting from snow melt) flows (from the mountain top through upper tunnel complex) out of the access tunnel without the need for pumping. While the underground drifts at Yucca Mountain, Nevada, have not yet been considered (since they are relatively shallow for physics experiments), they have undergone extensive earth science research for nearly 10 years, as the site for future storage of nation's spent nuclear fuels. All these underground sites could accommodate different earth science and physics experiments. Most underground physics experiments require depth to reduce the cosmic-ray-induced muon flux from atmospheric sources. Earth science experiments can be

  14. Integrating Real-time, Real-world Geoscience Experiences into Classroom Instruction with EarthLabs and the JOIDES Resolution

    NASA Astrophysics Data System (ADS)

    Mote, A. S.; Lockwood, J.; Ellins, K. K.; Haddad, N.; Cooper, S. K.; Ledley, T. S.

    2013-12-01

    Inspiring the next generation of geoscientists and preparing students for the 21st century workforce requires lifting science outside of the classroom and giving learners the opportunity to think critically about real-world geoscience problems. The EarthLabs suite of climate science modules challenges students with a variety of learning experiences including current scientific data analysis, computer visualizations, satellite imagery, and engaging videos. Each module includes a series of hands-on activities to allow students to explore Earth's complex and dynamic climate history, leading to a deeper understanding of present and future changes to our planet. A new EarthLabs module in development 'Climate Detectives: An Expedition on board the JOIDES Resolution," focuses on Integrated Ocean Drilling Program (IODP) Expedition 341 to Southern Alaska. The module is structured to allow students to work collaboratively, mimicking scientific research groups on the JOIDES Resolution. As students assume the role of a scientist, learn about data collection methods, and analyze authentic data, they learn about the climate history and tectonic processes of the Southern Alaska continental margin, as well as explore the relationship between climate, sedimentation, and tectonics. The Project Based Learning (PBL) approach used in the module teaches students how to analyze data and solve problems like scientists, strengthening the development of higher order thinking skills and preparing them for college coursework. The 'Climate Detectives' Module also provides students with opportunities to interact with scientists through live video conferencing and pre-recorded video presentations by scientists. In this presentation, Expedition 341 Education Officer, Alison Mote, describes the new module, which takes students on an educational journey as they learn about the scientific objectives, methods, and data collection tools scientists use to conduct research on sediment cores retrieved

  15. Integrating EarthScope Data Into Interactive Visualizations, Movies and High-Resolution Static Images

    NASA Astrophysics Data System (ADS)

    Kilb, D.

    2008-12-01

    What is EarthScope? The answer to this question can best be addressed through images, movies and interactive visualizations. Using these types of visual tools the temporal evolution and spatial scales of the various EarthScope data (e.g., earthquakes, sediment thickness, aquifers, focal mechanisms, topography, moho depth, mines, geology, magnetics, faults and gravity) can be more easily understood. Working with EarthScope researchers we have developed visualizations to assist with data quality (i.e., from SAFOD, USArray and PBO), hypothesis testing and the presentation of final results. Through this process we have identified 6 key areas of interest: (1) Depicting temporal evolution of data; (2) The ability to toggle on/off and color-code data sub-sets for complex high-density data; (3) Developing end-products that can be used as on-line supplements to journal articles; (4) Creating multi-use end-products that benefit researchers, emergency response personnel and education programs; (5) Quality assessing and geo-referencing newly collected data; and (6) Making difficult subjects more understandable. The visualizations we create can be accessed from our website (we get ~4,000 unique visitors to our pages each month) through the visual objects library at the Scripps Institution of Oceanography's Visualization Center (http://siovizcenter.ucsd.edu/library.php). These include 3D interactive visualizations, Quicktime movies and online tools and can be explored using freeware that runs on multiple platforms (e.g., Windows, Mac OS X, Linux, SGI Irix).

  16. Discover Earth

    NASA Technical Reports Server (NTRS)

    Steele, Colleen

    1998-01-01

    Discover Earth is a NASA-sponsored project for teachers of grades 5-12, designed to: (1) enhance understanding of the Earth as an integrated system; (2) enhance the interdisciplinary approach to science instruction; and (3) provide classroom materials that focus on those goals. Discover Earth is conducted by the Institute for Global Environmental Strategies in collaboration with Dr. Eric Barron, Director, Earth System Science Center, The Pennsylvania State University; and Dr. Robert Hudson, Chair, the Department of Meteorology, University of Maryland at College Park. The enclosed materials: (1) represent only part of the Discover Earth materials; (2) were developed by classroom teachers who are participating in the Discover Earth project; (3) utilize an investigative approach and on-line data; and (4) can be effectively adjusted to classrooms with greater/without technology access. The Discover Earth classroom materials focus on the Earth system and key issues of global climate change including topics such as the greenhouse effect, clouds and Earth's radiation balance, surface hydrology and land cover, and volcanoes and climate change. All the materials developed to date are available on line at (http://www.strategies.org) You are encouraged to submit comments and recommendations about these materials to the Discover Earth project manager, contact information is listed below. You are welcome to duplicate all these materials.

  17. On an improved sub-regional water resources management representation for integration into earth system models

    SciTech Connect

    Voisin, Nathalie; Li, Hongyi; Ward, Duane L.; Huang, Maoyi; Wigmosta, Mark S.; Leung, Lai-Yung R.

    2013-09-30

    Human influence on the hydrologic cycle includes regulation and storage, consumptive use and overall redistribution of water resources in space and time. Representing these processes is essential for applications of earth system models in hydrologic and climate predictions, as well as impact studies at regional to global scales. Emerging large-scale research reservoir models use generic operating rules that are flexible for coupling with earth system models. Those generic operating rules have been successful in reproducing the overall regulated flow at large basin scales. This study investigates the uncertainties of the reservoir models from different implementations of the generic operating rules using the complex multi-objective Columbia River Regulation System in northwestern United States as an example to understand their effects on not only regulated flow but also reservoir storage and fraction of the demand that is met. Numerical experiments are designed to test new generic operating rules that combine storage and releases targets for multi-purpose reservoirs and to compare the use of reservoir usage priorities, withdrawals vs. consumptive demand, as well as natural vs. regulated mean flow for calibrating operating rules. Overall the best performing implementation is the use of the combined priorities (flood control storage targets and irrigation release targets) operating rules calibrated with mean annual natural flow and mean monthly withdrawals. The challenge of not accounting for groundwater withdrawals, or on the contrary, assuming that all remaining demand is met through groundwater extractions, is discussed.

  18. Integrated Solid Earth Science: the right place and time to discover the unexpected? (Arthur Holmes Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Cloetingh, Sierd

    2013-04-01

    -level. Those cycles were detected as a result of the pioneering work on the stratigraphic record of sedimentary basins and continental margins from all over the world by Peter Vail, Bilal Haq and others from Exxon. It was at this time, that sedimentary basins became a frontier in the integration of quantitative geology and geophysics. Sedimentary basins do not only provide a powerful source of information on the evolution of the underlying lithosphere and climate fluctuations, but also contain mankind's main reservoirs of geo-energy and geo-resources. It was Peter Ziegler, head of global geology at Shell International, who was the prime mentor in my somewhat unexpected scientific journey in sedimentary basins. These became the main research target of the Tectonics research group I established in 1988 in Amsterdam. In these years it became increasingly evident that the rheology of the lithosphere exerts a crucial control on the evolution of basins, but also on continental topography. It is on this topic that the cooperation over more than two decades with Evgenii Burov, addressing issues like the rheological structure of Europe's lithosphere, rift shoulder uplift and the interplay of lithospheric folding and mantle-lithosphere interactions, has, been very fruitful. Another unexpected milestone has been the opportunity to build up, parallel to the research efforts in field studies and numerical modeling, an analogue tectonic laboratory in our group. This brings me to another issue, also completely unforeseen: the integration of earth science in Europe, particularly taking off after the disappearance of the Iron Curtain. For my group, the latter marked the beginning of a very fruitful cooperation in particular with the groups of Frank Horvath in Budapest and Cornel Dinu in Bucharest, addressing the fascinating solid Earth dynamics of the Carpathians and Pannonian basin. Over the last few years, it has been become evident that integration in the solid earth science is the way to

  19. Native American Science Education: A Compelling Opportunity for the Integration of Earth and Space Science

    NASA Astrophysics Data System (ADS)

    Morrow, C. A.; Maryboy, N.; Begay, D.

    2005-05-01

    The strong relationships between Earth and sky in the worldviews of Native American people presents a wonderful opportunity for collaborations that can co-create compelling educational opportunities for both Native and non-Native learners. This paper will discuss the relationship among successful science education for Native Americans, standards-based science education, and informal science education. It will address some strategies for combining best practice in education with a deep cultural authenticity. Presenting astronomy in a culturally relevant and correct way is not only of value to the Native learner, but it is also of value to the non-Native learner because cultural relevance for Native people demands that science be presented via different learning modalities (e.g. visual, kinesthetic, tactile) and in a way that is more interconnected with other science and non-science disciplines. This kind of multi-modal and interdisciplinary approach is valuable and progressive for Non-native learners as well.

  20. Effect of Knowledge Integration Activities on Students' Perception of the Earth's Crust as a Cyclic System.

    ERIC Educational Resources Information Center

    Kali, Yael; Orion, Nir; Eylon, Bat-Sheva

    2003-01-01

    Characterizes students' understanding of the rock cycle system. Examines effects of a knowledge integration activity on their system thinking. Interprets answers to an open-ended test using a systems thinking continuum ranging from a completely static view of the system to an understanding of the system's cyclic nature. Reports meaningful…

  1. Moving NASA Beyond Low Earth Orbit: Future Human-Automation-Robotic Integration Challenges

    NASA Technical Reports Server (NTRS)

    Marquez, Jessica

    2016-01-01

    This presentation will provide an overview of current human spaceflight operations. It will also describe how future exploration missions will have to adapt and evolve in order to deal with more complex missions and communication latencies. Additionally, there are many implications regarding advanced automation and robotics, and this presentation will outline future human-automation-robotic integration challenges.

  2. Challenges of agricultural monitoring: integration of the Open Farm Management Information System into GEOSS and Digital Earth

    NASA Astrophysics Data System (ADS)

    Řezník, T.; Kepka, M.; Charvát, K.; Charvát, K., Jr.; Horáková, S.; Lukas, V.

    2016-04-01

    From a global perspective, agriculture is the single largest user of freshwater resources, each country using an average of 70% of all its surface water supplies. An essential proportion of agricultural water is recycled back to surface water and/or groundwater. Agriculture and water pollution is therefore the subject of (inter)national legislation, such as the Clean Water Act in the United States of America, the European Water Framework Directive, and the Law of the People's Republic of China on the Prevention and Control of Water Pollution. Regular monitoring by means of sensor networks is needed in order to provide evidence of water pollution in agriculture. This paper describes the benefits of, and open issues stemming from, regular sensor monitoring provided by an Open Farm Management Information System. Emphasis is placed on descriptions of the processes and functionalities available to users, the underlying open data model, and definitions of open and lightweight application programming interfaces for the efficient management of collected (spatial) data. The presented Open Farm Management Information System has already been successfully registered under Phase 8 of the Global Earth Observation System of Systems (GEOSS) Architecture Implementation Pilot in order to support the wide variety of demands that are primarily aimed at agriculture pollution monitoring. The final part of the paper deals with the integration of the Open Farm Management Information System into the Digital Earth framework.

  3. Integrated propulsion for near-Earth space missions. Volume 2: Technical

    NASA Technical Reports Server (NTRS)

    Dailey, C. L.; Meissinger, H. F.; Lovberg, R. H.; Zafran, S.

    1981-01-01

    The calculation approach is described for parametric analysis of candidate electric propulsion systems employed in LEO to GEO missions. Occultation relations, atmospheric density effects, and natural radiation effects are presented. A solar cell cover glass tradeoff is performed to determine optimum glass thickness. Solar array and spacecraft pointing strategies are described for low altitude flight and for optimum array illumination during ascent. Mass ratio tradeoffs versus transfer time provide direction for thruster technology improvements. Integrated electric propulsion analysis is performed for orbit boosting, inclination change, attitude control, stationkeeping, repositioning, and disposal functions as well as power sharing with payload on orbit. Comparison with chemical auxiliary propulsion is made to quantify the advantages of integrated propulsion in terms of weight savings and concomittant launch cost savings.

  4. Computational Challenges in Integrated Regional Earth System Modeling (iRESM)

    NASA Astrophysics Data System (ADS)

    Kleese van Dam, K.; Hibbard, K. A.; Gorton, I.; Liu, Y.

    2010-12-01

    Policy and decision making, in response to climate change, will require both economic and environmental tradeoffs. Decisions about allocating scarce water across competing municipal, agricultural, and ecosystem demands is just one of the challenges ahead, along with decisions regarding competing land use priorities such as biofuels, food, and species habitat. Assessing potential mitigation actions must include processes at a global level and extended time frame. However, adaptation is more relevant on a regional scale and in a shorter time frame, which encourages current research to address mitigation and adaptation separately, even though strategies for mitigation influence our ability for adaptation, and vice versa, none have attempted to fully integrate human and environmental processes at the regional level. The fundamental goal of the iRESM initiative is the critical analyses of the tradeoffs and consequences of decision and policy making on the background of integrated human and environmental systems, combining the different scientific processes, bridging different temporal and geographic scales and resolving the semantic differences between them. Hereby the iRESM Initiative will work in the first instance with the climate, socio-economic, crop and energy modeling communities to develop an initial system. The computational challenges faced by the project go hand in hand with the scientific ones, as the researchers from different domains are starting to bridge the gaps, an adaptive computational framework needs to be established that facilitates the integration and transition across different geographical, time, thematic and semantic divides. With an expectation that more diverse processes and interchanges will be added in the future the framework also needs to be adaptive and flexible, providing the ability to grow with the project needs. We provide an overview of the iRESM initiative from PNNL with the initial architectural framework to evaluate the

  5. An integrated study of earth resources in the state of California based on ERTS-1 and supporting aircraft data

    NASA Technical Reports Server (NTRS)

    Colwell, R. N.; Thorley, G. A.; Burgy, R. H.; Schubert, G.; Estes, J. E.; Bowden, L. W.; Algazi, V. R.; Wildman, W. E.; Huntington, G. L. (Principal Investigator)

    1972-01-01

    There are no author-identified significant results in this report. Results of an integrated study of earth resources in the state of California using ERTS-1 and supporting aircraft data are presented. Areas of investigation cover (1) regional agricultural surveys; (2) solving water resource management problems; (3) resource management in Northern California using ERTS-1 data; (4) analysis of river meanders; (5) assessment and monitoring change in west side of the San Joaquin Valley and central coastal zone of state; (6) assessment and monitoring of changes in Southern California environment; (7) digital handling and processing of ERTS-1 data; (8) use of ERTS-1 data in educational and applied research programs of the Agricultural Extension Service; and (9) identification, classification, and mapping of salt affected soils.

  6. Combining sky and earth: desert ants (Melophorus bagoti) show weighted integration of celestial and terrestrial cues.

    PubMed

    Legge, Eric L G; Wystrach, Antoine; Spetch, Marcia L; Cheng, Ken

    2014-12-01

    Insects typically use celestial sources of directional information for path integration, and terrestrial panoramic information for view-based navigation. Here we set celestial and terrestrial sources of directional information in conflict for homing desert ants (Melophorus bagoti). In the first experiment, ants learned to navigate out of a round experimental arena with a distinctive artificial panorama. On crucial tests, we rotated the arena to create a conflict between the artificial panorama and celestial information. In a second experiment, ants at a feeder in their natural visually-cluttered habitat were displaced prior to their homing journey so that the dictates of path integration (feeder to nest direction) based on a celestial compass conflicted with the dictates of view-based navigation (release point to nest direction) based on the natural terrestrial panorama. In both experiments, ants generally headed in a direction intermediate to the dictates of celestial and terrestrial information. In the second experiment, the ants put more weight on the terrestrial cues when they provided better directional information. We conclude that desert ants weight and integrate the dictates of celestial and terrestrial information in determining their initial heading, even when the two directional cues are highly discrepant.

  7. Distributed Earth observation data integration and on-demand services based on a collaborative framework of geospatial data service gateway

    NASA Astrophysics Data System (ADS)

    Xie, Jibo; Li, Guoqing

    2015-04-01

    Earth observation (EO) data obtained by air-borne or space-borne sensors has the characteristics of heterogeneity and geographical distribution of storage. These data sources belong to different organizations or agencies whose data management and storage methods are quite different and geographically distributed. Different data sources provide different data publish platforms or portals. With more Remote sensing sensors used for Earth Observation (EO) missions, different space agencies have distributed archived massive EO data. The distribution of EO data archives and system heterogeneity makes it difficult to efficiently use geospatial data for many EO applications, such as hazard mitigation. To solve the interoperable problems of different EO data systems, an advanced architecture of distributed geospatial data infrastructure is introduced to solve the complexity of distributed and heterogeneous EO data integration and on-demand processing in this paper. The concept and architecture of geospatial data service gateway (GDSG) is proposed to build connection with heterogeneous EO data sources by which EO data can be retrieved and accessed with unified interfaces. The GDSG consists of a set of tools and service to encapsulate heterogeneous geospatial data sources into homogenous service modules. The GDSG modules includes EO metadata harvesters and translators, adaptors to different type of data system, unified data query and access interfaces, EO data cache management, and gateway GUI, etc. The GDSG framework is used to implement interoperability and synchronization between distributed EO data sources with heterogeneous architecture. An on-demand distributed EO data platform is developed to validate the GDSG architecture and implementation techniques. Several distributed EO data achieves are used for test. Flood and earthquake serves as two scenarios for the use cases of distributed EO data integration and interoperability.

  8. Integration of lessons from recent research for "Earth to Mars" life support systems

    NASA Astrophysics Data System (ADS)

    Nelson, M.; Allen, J. P.; Alling, A.; Dempster, W. F.; Silverstone, S.; van Thillo, M.

    Development of reliable and robust strategies for long-term life support for mbox planetary exploration needs to be built on real-time experimentation to verify and improve system components Also critical is the incorporation of a range of viable options to handle potential short-term life system imbalances This paper revisits some of the conceptual framework for a Mars base prototype previously advanced Mars on Earth in the light of three years of experimentation by the authors in the Laboratory Biosphere further investigation of system alternatives and the advent of other innovative engineering and agri-ecosystem approaches Several experiments with candidate space agriculture crops have demonstrated the higher productivity possible with elevated light levels and improved environmental controls For example crops of sweet potatoes exceeded original Mars base prototype projections by 83 ultradwarf Apogee wheat by 27 pinto bean by 240 and cowpeas slightly exceeded anticipated dry bean yield These production levels although they may be increased with further optimization of lighting regimes environmental parameters crop density etc offer evidence that a soil-based system can be as productive as the hydroponic systems which have dominated space life support scenarios and research Soil also offers several distinct advantages the capability to be created using in-situ space resources reducing reliance on consumables and imported resources and more easily recycling and

  9. Towards an Integrated Model of Earth's Thermo-Chemical Evolution and Plate Tectonics

    NASA Astrophysics Data System (ADS)

    Tackley, P. J.; Xie, S.

    2001-05-01

    It has long been a challenge for geodynamicists, who have typically modeled homogeneous mantles, to explain the geochemical evidence for the existence of several distinct chemical reservoirs, in terms of a dynamically and chemically self-consistent model. While the mixing behavior of generalized tracers has received much attention in the modeling community, a recent trend has been towards mantle convection models that track the evolution of specific chemical species, both major and minor, and can thus be related to geochemical observations. However, obtaining realistic chemical evolution in such models is dependent on their having a reasonable representation of plate tectonic behavior since the recycling of oceanic crust and complementary depleted residuum is a key process in Earth that other terrestrial planets may lack. In general, this has required inserting plate motions by hand in models. In recent years, however, we have learned how to perform numerical simulations of mantle convection in which plate tectonic behavior is introduced self-consistently through plastic yielding of the lithosphere. In this presentation, models of mantle convection that combine a treatment of geochemical evolution with self-consistently generated plate tectonics, will be presented. Preliminary results indicate that the system can self-consistently evolve regions which have a HIMU-like signature as well as regions with a high He3/He4 ratio.

  10. Towards Designing an Integrated Earth Observation System for the Provision of Solar Energy Resource and Assessment

    NASA Technical Reports Server (NTRS)

    Stackouse, Paul W., Jr.; Renne, D.; Beyer, H.-G.; Wald, L.; Meyers, R.; Perez, R.; Suri, M.

    2006-01-01

    The GEOSS strategic plan specifically targets the area of improved energy resource management due to the importance of these to the economic and social viability of every nation of the world. With the world s increasing demand for energy resources, the need for new alternative energy resources grows. This paper overviews a new initiative within the International Energy Agency that addresses needs to better manage and develop solar energy resources worldwide. The goal is to provide the solar energy industry, the electricity sector, governments, and renewable energy organizations and institutions with the most suitable and accurate information of the solar radiation resources at the Earth's surface in easily-accessible formats and understandable quality metrics. The scope of solar resource assessment information includes historic data sets and currently derived data products using satellite imagery and other means. Thus, this new task will address the needs of the solar energy sector while at the same time will serve as a model that satisfies GEOSS objectives and goals.

  11. Visual-vestibular integration as a function of adaptation to space flight and return to Earth

    NASA Technical Reports Server (NTRS)

    Reschke, Millard R.; Bloomberg, Jacob J.; Harm, Deborah L.; Huebner, William P.; Krnavek, Jody M.; Paloski, William H.; Berthoz, Alan

    1999-01-01

    Research on perception and control of self-orientation and self-motion addresses interactions between action and perception . Self-orientation and self-motion, and the perception of that orientation and motion are required for and modified by goal-directed action. Detailed Supplementary Objective (DSO) 604 Operational Investigation-3 (OI-3) was designed to investigate the integrated coordination of head and eye movements within a structured environment where perception could modify responses and where response could be compensatory for perception. A full understanding of this coordination required definition of spatial orientation models for the microgravity environment encountered during spaceflight.

  12. Entrainment of bed material by Earth-surface mass flows: review and reformulation of depth-integrated theory

    USGS Publications Warehouse

    Iverson, Richard M.; Chaojun Ouyang,

    2015-01-01

    Earth-surface mass flows such as debris flows, rock avalanches, and dam-break floods can grow greatly in size and destructive potential by entraining bed material they encounter. Increasing use of depth-integrated mass- and momentum-conservation equations to model these erosive flows motivates a review of the underlying theory. Our review indicates that many existing models apply depth-integrated conservation principles incorrectly, leading to spurious inferences about the role of mass and momentum exchanges at flow-bed boundaries. Model discrepancies can be rectified by analyzing conservation of mass and momentum in a two-layer system consisting of a moving upper layer and static lower layer. Our analysis shows that erosion or deposition rates at the interface between layers must in general satisfy three jump conditions. These conditions impose constraints on valid erosion formulas, and they help determine the correct forms of depth-integrated conservation equations. Two of the three jump conditions are closely analogous to Rankine-Hugoniot conditions that describe the behavior of shocks in compressible gasses, and the third jump condition describes shear traction discontinuities that necessarily exist across eroding boundaries. Grain-fluid mixtures commonly behave as compressible materials as they undergo entrainment, because changes in bulk density occur as the mixtures mobilize and merge with an overriding flow. If no bulk density change occurs, then only the shear-traction jump condition applies. Even for this special case, however, accurate formulation of depth-integrated momentum equations requires a clear distinction between boundary shear tractions that exist in the presence or absence of bed erosion.

  13. Application of Manifold Methods for Data Assimilation in Integrated Earth System Models

    NASA Astrophysics Data System (ADS)

    Safaie, A.; Dang, C.; Radha, H.; Phanikumar, M. S.

    2015-12-01

    A novel manifold-based method is presented to assimilate different types of spatio-temporal data in integrated land and oceanic models. This method has been developed based on the assumption that hydrologic, atmospheric and oceanic data can be mapped onto an underlying differential manifold. In this study, the proposed method is employed to reconstruct meteorological forcing dataset over Lake Michigan, bathymetry of Gull Lake, and precipitation over the Grand River watershed in the State of Michigan. In the first case study, hourly interpolated meteorological forcing parameters are used to run a three-dimensional hydrodynamic model of Lake Michigan to show the improvement that results from the use of the interpolation method by comparing model results with observed data for currents. In the second case study, the bathymetry of the Gull Lake is interpolated from the scatter point data using the manifold technique. A hydrodynamic model of Gull Lake has been developed and improved by using the interpolated bathymetry. In the last case study, 13-year daily participation data are interpolated over the Grand River watershed and used as input for an integrated, distributed watershed model. All three case studies illustrate the effectiveness of the presented manifold based interpolation algorithm.

  14. Earth tides

    SciTech Connect

    Harrison, J.C.

    1984-01-01

    Nineteen papers on gravity, tilt, and strain tides are compiled into this volume. Detailed chapters cover the calculation of the tidal forces and of the Earth's response to them, as well as actual observations of earth tides. Partial Contents: On Earth tides. The tidal forces: Tidal Forces. New Computations of the Tide-Generating Potential. Corrected Tables of Tidal Harmonics. The Theory of Tidal Deformations. Body Tides on an Elliptical, Rotating, Elastic and Oceanless Earth, Deformation of the Earth by Surface Loads. Gravimetric Tidal Loading Computed from Integrated Green's Functions. Tidal Friction in the Solid Earth. Loading Tides Versus Body Tides. Lunar Tidal Acceleration from Earth Satellite Orbit Analysis. Observations: gravity. Tidal Gravity in Britain: Tidal Loading and the Spatial Distribution of the Marine Tide. Tidal Loading along a Profile Europe-East Africa-South Asia-Australia and the Pacific Ocean. Detailed Gravity-Tide Spectrum between One and Four Cycles per Day. Observations: tilt and strain. Cavity and Topographic Effects in Tilt and Strain Measurement. Observations of Local Elastic Effects on Earth Tide Tilts and Strains.

  15. Multidisciplinary integrated field campaign to an acidic Martian Earth analogue with astrobiological interest: Rio Tinto

    NASA Astrophysics Data System (ADS)

    Gómez, F.; Walter, N.; Amils, R.; Rull, F.; Klingelhöfer, A. K.; Kviderova, J.; Sarrazin, P.; Foing, B.; Behar, A.; Fleischer, I.; Parro, V.; Garcia-Villadangos, M.; Blake, D.; Martin Ramos, J. D.; Direito, S.; Mahapatra, P.; Stam, C.; Venkateswaran, K.; Voytek, M.

    2011-07-01

    Recently reported results from latest Mars Orbiters and Rovers missions are transforming our opinion about the red planet. That dry and inhospitable planet reported in the past is becoming a wetter planet with high probabilities of water existence in the past. Nowadays, some results seem to indicate the presence of water beneath the Mars surface. But also mineralogy studies by NASA Opportunity Rover report iron oxides and hydroxides precipitates on Endurance Crater. Sedimentary deposits have been identified at Meridiani Planum. These deposits must have generated in a dune aqueous acidic and oxidizing environment. Similarities appear when we study Rio Tinto, and acidic river under the control of iron. The discovery of extremophiles on Earth widened the window of possibilities for life to develop in the Universe, and as a consequence on Mars and other planetary bodies with astrobiological interest. The compilation of data produced by the ongoing missions offers an interested view for life possibilities to exist: signs of an early wet Mars and rather recent volcanic activity as well as ground morphological characteristics that seem to be promoted by liquid water. The discovery of important accumulations of sulfates and the existence of iron minerals such as jarosite in rocks of sedimentary origin has allowed specific terrestrial models to come into focus. Río Tinto (Southwestern Spain, Iberian Pyritic Belt) is an extreme acidic environment, product of the chemolithotrophic activity of micro-organisms that thrive in the massive pyrite-rich deposits of the Iberian Pyritic Belt. Some particular protective environments should house the organic molecules and bacterial life forms in harsh environments such as Mars surface supporting microniches inside precipitated minerals or inside rocks. Terrestrial analogues could help us to afford the comprehension of habitability (on other planetary bodies). We are reporting here the multidisciplinary study of some endolithic niches

  16. Crystal surface integrity and diffusion measurements on Earth and planetary materials

    NASA Astrophysics Data System (ADS)

    Watson, E. B.; Cherniak, D. J.; Thomas, J. B.; Hanchar, J. M.; Wirth, R.

    2016-09-01

    Characterization of diffusion behavior in minerals is key to providing quantitative constraints on the ages and thermal histories of Earth and planetary materials. Laboratory experiments are a vital source of the needed diffusion measurements, but these can pose challenges because the length scales of diffusion achievable in a laboratory time are commonly less than 1 μm. An effective strategy for dealing with this challenge is to conduct experiments involving inward diffusion of the element of interest from a surface source, followed by quantification of the resulting diffusive-uptake profile using a high-resolution depth-profiling technique such as Rutherford backscattering spectroscopy (RBS), nuclear reaction analysis (NRA), or ion microprobe (SIMS). The value of data from such experiments is crucially dependent on the assumption that diffusion in the near-surface of the sample is representative of diffusion in the bulk material. Historical arguments suggest that the very process of preparing a polished surface for diffusion studies introduces defects-in the form of dislocations and cracks-in the outermost micrometer of the sample that make this region fundamentally different from the bulk crystal in terms of its diffusion properties. Extensive indirect evidence suggests that, in fact, the near-surface region of carefully prepared samples is no different from the bulk crystal in terms of its diffusion properties. A direct confirmation of this conclusion is nevertheless clearly important. Here we use transmission electron microscopy to confirm that the near-surface regions of olivine, quartz and feldspar crystals prepared using careful polishing protocols contain no features that could plausibly affect diffusion. This finding does not preclude damage to the mineral structure from other techniques used in diffusion studies (e.g., ion implantation), but even in this case the role of possible structural damage can be objectively assessed and controlled. While all

  17. Research priorities in land use and land-cover change for the Earth system and integrated assessment modelling

    SciTech Connect

    Hibbard, Kathleen A.; Janetos, Anthony C.; Van Vuuren, Detlef; Pongratz, Julia; Rose, Steven K.; Betts, Richard; Herold, Martin; Feddema, Johannes J.

    2010-11-15

    This special issue has highlighted recent and innovative methods and results that integrate observations and AQ3 modelling analyses of regional to global aspect of biophysical and biogeochemical interactions of land-cover change with the climate system. Both the Earth System and the Integrated Assessment modeling communities recognize the importance of an accurate representation of land use and land-cover change to understand and quantify the interactions and feedbacks with the climate and socio-economic systems, respectively. To date, cooperation between these communities has been limited. Based on common interests, this work discusses research priorities in representing land use and land-cover change for improved collaboration across modelling, observing and measurement communities. Major research topics in land use and land-cover change are those that help us better understand (1) the interaction of land use and land cover with the climate system (e.g. carbon cycle feedbacks), (2) the provision of goods and ecosystem services by terrestrial (natural and anthropogenic) land-cover types (e.g. food production), (3) land use and management decisions and (4) opportunities and limitations for managing climate change (for both mitigation and adaptation strategies).

  18. Role of electron-electron interactions in the charge dynamics of rare-earth-doped CaF e2A s2

    NASA Astrophysics Data System (ADS)

    Xing, Zhen; Huffman, T. J.; Xu, Peng; Hollingshad, A. J.; Brooker, D. J.; Penthorn, N. E.; Qazilbash, M. M.; Saha, S. R.; Drye, T.; Roncaioli, C.; Paglione, J.

    2016-08-01

    We have investigated the charge dynamics and the nature of many-body interactions in La- and Pr- doped CaF e2A s2 . From the infrared part of the optical conductivity, we discover that the scattering rate of mobile carriers above 200 K exhibits saturation at the Mott-Ioffe-Regel limit of metallic transport. However, the dc resistivity continues to increase with temperature above 200 K due to the loss of Drude spectral weight. The loss of Drude spectral weight with increasing temperature is seen in a wide temperature range in the uncollapsed tetragonal phase, and this spectral weight is recovered at energy scales about one order of magnitude larger than the Fermi energy scale in these semimetals. The phenomena noted above have been observed previously in other correlated metals in which the dominant interactions are electronic in origin. Further evidence of significant electron-electron interactions is obtained from the presence of quadratic temperature and frequency-dependent terms in the scattering rate at low temperatures and frequencies in the uncollapsed tetragonal structures of La-doped and Pr-doped CaF e2A s2 . For temperatures below the structure collapse transition in Pr-doped CaF e2A s2 at ˜70 K , the scattering rate decreases due to weakening of electronic correlations, and the Drude spectral weight decreases due to modification of the low-energy electronic structure.

  19. Rare Earth Ion Effects on the Pseudo-Gap in Electron-Doped Superconductors And Possible Nodeless D-Wave Gap

    SciTech Connect

    Park, S.R.; Leem, C.S.; Roh, Y.S.; Choi, K.J.; Kim, J.H.; Kim, B.J.; Koh, H.; Eisaki, H.; Lu, D.H.; Shen, Z.-X.; Armitage, N.P.; Kim, C.

    2009-05-21

    We report angle resolved photoemission (ARPES) studies on electron-doped cuprate superconductor Sm{sub 2-x}Ce{sub x}CuO{sub 4} (x = 0.14 and 0.18). A wide energy range scan shows clear 'waterfall' effect at an energy scale close to 500 meV which is consistent with the value found in Nd{sub 2-x}Ce{sub x}CuO{sub 4} (NCCO) but larger than that from hole-doped superconductors. High resolution results from both dopings show pseudo-gap effects that were observed in NCCO. However, the effects are found to be stronger than that observed in optimally doped NCCO. The overall electronic structure is well understood within a simple model in which a {radical}2 x {radical}2 static order is assumed. Both ARPES and optical measurements give the coupling strengths to the Q = ({pi}/2,{pi}/2) (due to the {radical}2 x {radical}2 order) to be about 0.1 eV, compatible with each other. The effect is strong enough to push the band near the nodal region below the Fermi energy, resulting in possible nodeless d-wave superconductivity where zero energy quasi-particle excitation is inhibited.

  20. Synthesis and characterization of rare-earth doped SrBi{sub 2}Nb{sub 2}O{sub 9} phase in lithium borate based nanocrystallized glasses

    SciTech Connect

    Harihara Venkataraman, B.; Fujiwara, Takumi; Komatsu, Takayuki

    2009-06-15

    Glass composites comprising of un-doped and samarium-doped SrBi{sub 2}Nb{sub 2}O{sub 9} nanocrystallites are fabricated in the glass system 16.66SrO-16.66[(1-x)Bi{sub 2}O{sub 3}-xSm{sub 2}O{sub 3}]-16.66Nb{sub 2}O{sub 5}-50Li{sub 2}B{sub 4}O{sub 7} (0<=x<=0.5, in mol%) via the melt quenching technique. The glassy nature of the as-quenched samples is established by differential thermal analyses. Transmission electron microscopic studies reveal the presence of about 15 nm sized spherical crystallites of the fluorite-like SrBi{sub 1.9}Sm{sub 0.1}Nb{sub 2}O{sub 9} phase in the samples heat treated at 530 deg. C. The formation of layered perovskite-type un-doped and samarium-doped SrBi{sub 2}Nb{sub 2}O{sub 9} nanocrystallites with an orthorhombic structure through the intermediate fluorite phase is confirmed by X-ray powder diffraction and micro-Raman spectroscopic studies. The influence of samarium doping on the lattice parameters, lattice distortions, and the Raman peak positions of SrBi{sub 2}Nb{sub 2}O{sub 9} perovskite phase is clarified. The dielectric constants of the perovskite SrBi{sub 2}Nb{sub 2}O{sub 9} and SrBi{sub 1.9}Sm{sub 0.1}Nb{sub 2}O{sub 9} nanocrystals are relatively larger than those of the corresponding fluorite-like phase and the precursor glass. - Graphical Abstract: This figure shows the XRD patterns at room temperature for the as-quenched and heat treated samples in Sm{sub 2}O{sub 3}-doped (x=0.1) glass. Based on these results, it is concluded that the formation of samarium-doped perovskite SBN phase takes place via an intermediate fluorite-like phase in the crystallization of this glass.

  1. Geo-Semantic Framework for Integrating Long-Tail Data and Model Resources for Advancing Earth System Science

    NASA Astrophysics Data System (ADS)

    Elag, M.; Kumar, P.

    2014-12-01

    Often, scientists and small research groups collect data, which target to address issues and have limited geographic or temporal range. A large number of such collections together constitute a large database that is of immense value to Earth Science studies. Complexity of integrating these data include heterogeneity in dimensions, coordinate systems, scales, variables, providers, users and contexts. They have been defined as long-tail data. Similarly, we use "long-tail models" to characterize a heterogeneous collection of models and/or modules developed for targeted problems by individuals and small groups, which together provide a large valuable collection. Complexity of integrating across these models include differing variable names and units for the same concept, model runs at different time steps and spatial resolution, use of differing naming and reference conventions, etc. Ability to "integrate long-tail models and data" will provide an opportunity for the interoperability and reusability of communities' resources, where not only models can be combined in a workflow, but each model will be able to discover and (re)use data in application specific context of space, time and questions. This capability is essential to represent, understand, predict, and manage heterogeneous and interconnected processes and activities by harnessing the complex, heterogeneous, and extensive set of distributed resources. Because of the staggering production rate of long-tail models and data resulting from the advances in computational, sensing, and information technologies, an important challenge arises: how can geoinformatics bring together these resources seamlessly, given the inherent complexity among model and data resources that span across various domains. We will present a semantic-based framework to support integration of "long-tail" models and data. This builds on existing technologies including: (i) SEAD (Sustainable Environmental Actionable Data) which supports curation

  2. Expedition Earth and Beyond: Using NASA data resources and integrated educational strategies to promote authentic research in the classroom

    NASA Astrophysics Data System (ADS)

    Graff, P. V.; Stefanov, W.; Willis, K.; Runco, S.

    2009-12-01

    Teachers in today’s classrooms are bound by state required skills, education standards, and high stakes testing. How can they gain skills and confidence to replace units or individual activities with curriculum that incorporates project and inquiry-based learning and promotes authentic research in the classroom? The key to promoting classroom authentic research experiences lies in educator professional development that is structured around teacher needs. The Expedition Earth and Beyond Program is a new geosciences program based at the NASA Johnson Space Center designed to engage, inspire and educate teachers and students in grades 5-14. The program promotes authentic research experiences for classrooms and uses strategies that will help NASA reach its education goals while still allowing educators to teach required standards. Teachers will have access to experts in terrestrial and planetary remote sensing and geoscience; this will enhance their use of content, structure, and relevant experiences to gain the confidence and skills they need to actively engage students in authentic research experiences. Integrated and powerful educational strategies are used to build skills and confidence in teachers. The strategies are as follows: 1) creating Standards-aligned, inquiry-based curricular resources as ready-to-use materials that can be modified by teachers to fit their unique classroom situation; 2) providing ongoing professional development opportunities that focus on active experiences using curricular materials, inquiry-based techniques and expanding content knowledge; 3) connecting science experts to classrooms to deepen content knowledge and provide relevance to classroom activities and real world applications; 4) facilitating students sharing research with their peers and scientists reinforcing their active participation and contributions to research. These components of the Expedition Earth and Beyond Education Program will be enhanced by providing exciting and

  3. Svalbard Integrated Arctic Earth Observing System (sios): Facilitating Easy Access to Multidisciplinary Arctic Data Through the Brokering Approach.

    NASA Astrophysics Data System (ADS)

    Bye, B. L.; Godøy, Ø.

    2014-12-01

    Environmental and climate changes are important elements of our global challenges. They are observed at a global scale and in particular in the Arctic. In order to give better estimates of the future changes, the Arctic has to be monitored and analyzed by a multi-disciplinary observation system that will improve Earth System Models. The best chance to achieve significant results within a relatively short time frame is found in regions with a large natural climate gradient, and where processes sensitive to the expected changes are particularly important. Svalbard and the surrounding ocean areas fulfil all these criteria. The vision for SIOS is to be a regional observational system for long term acquisition and proliferation of fundamental knowledge on global environmental change within an Earth System Science perspective in and around Svalbard. SIOS will systematically develop and implement methods for how observational networks are to be construed. The distributed SIOS data management system (SDMS) will be implemented through a combination of technologies tailored to the multi-disciplinary nature of the Arctic data. One of these technologies is The Brokering approach or "Framework". The Brokering approach provides a series of services such as discovery, access, transformation and semantics support to enable translation from one discipline/culture to another. This is exactly the challenges the SDMS will have to handle and thus the Brokering approach is integrated in the design of the system. A description of the design strategy for the SDMS that includes The Brokering approach will be presented. The design and implementation plans for the SDMS are based on research done in the EU funded ESFRI project SIOS and examples of solutions for interoperable systems producing Arctic datasets and products coordinated through SIOS will be showcased. The reported experience from SIOS brokering approach will feed into the process of developing a sustainable brokering governance

  4. Expedition Earth and Beyond: Using NASA Data Resources and Integrated Educational Strategies to Promote Authentic Research in the Classroom

    NASA Technical Reports Server (NTRS)

    Graffi, Paige Valderrama; Stefanov, William; Willis, Kim; Runco, Sue

    2009-01-01

    Teachers in today s classrooms are bound by state required skills, education standards, and high stakes testing. How can they gain skills and confidence to replace units or individual activities with curriculum that incorporates project and inquiry-based learning and promotes authentic research in the classroom? The key to promoting classroom authentic research experiences lies in educator professional development that is structured around teacher needs. The Expedition Earth and Beyond Program is a new geosciences program based at the NASA Johnson Space Center designed to engage, inspire and educate teachers and students in grades 5-14. The program promotes authentic research experiences for classrooms and uses strategies that will help NASA reach its education goals while still allowing educators to teach required standards. Teachers will have access to experts in terrestrial and planetary remote sensing and geoscience; this will enhance their use of content, structure, and relevant experiences to gain the confidence and skills they need to actively engage students in authentic research experiences. Integrated and powerful educational strategies are used to build skills and confidence in teachers. The strategies are as follows: 1) creating Standards-aligned, inquiry-based curricular resources as ready-to-use materials that can be modified by teachers to fit their unique classroom situation; 2) providing ongoing professional development opportunities that focus on active experiences using curricular materials, inquiry-based techniques and expanding content knowledge; 3) connecting science experts to classrooms to deepen content knowledge and provide relevance to classroom activities and real world applications; 4) facilitating students sharing research with their peers and scientists reinforcing their active participation and contributions to research. These components of the Expedition Earth and Beyond Education Program will be enhanced by providing exciting and

  5. Selective Emitter Pumped Rare Earth Laser

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L. (Inventor); Patton, Martin O. (Inventor)

    2001-01-01

    A selective emitter pumped rare earth laser provides an additional type of laser for use in many laser applications. Rare earth doped lasers exist which are pumped with flashtubes or laser diodes. The invention uses a rare earth emitter to transform thermal energy input to a spectral band matching the absorption band of a rare earth in the laser in order to produce lasing.

  6. A Critical Path for Data Integration in the U.S. Earth Sciences

    NASA Astrophysics Data System (ADS)

    Gallagher, K. T.; Allison, M. L.

    2011-12-01

    Development efforts for the U.S. Geoscience Information Network (US GIN) have crystallized around the Community for Data Integration (CDI) at the USGS, and the 50-state AASG State Geothermal Data project. The next step in developing a USGS-AASG community is to bring these two efforts into closer alignment through greater participation in CDI activities by geoinformatics practitioners from state geological surveys, and implementation of test bed activities by the USGIN partners. Test bed activities in the geological survey community will define a scope and provide a foundation to promote the use of specifications developed by the larger geoinformatics community. Adoption of some of these specifications as 'standards' by USGS and AASG for use by those organizations will lend authority and motivate wider adoption. The arc from use case to test bed to production deployments to agreement on 'standard' specifications for data discovery and access must be propelled by active interest from the user communities who have a stake in the outcome. The specifications developed will benefit the organizations involved in development, testing and deployment, which motivates participation -- a model that has worked successfully for standards organizations such as OGC, ISO and OASIS. The governance structure to support such a community process should promote grass root nucleation of interest groups that are the core of development efforts. Some mechanism for community agreement on priorities is desirable because geological survey agencies will need to allocate resources to support development. Loosely knit organizations such as ESIP and the current CDI provide models for this kind of structure. Because many geological surveys have data archive and dissemination functions as part of their portfolio, some support for the system can be built into the operating expenses and overhead. Sharing of resources and reuse of components can reduce the cost. Wide adoption of similar software

  7. MODELING THE DYNAMICS OF THE INTEGRATED EARTH SYSTEM AND THE VALUE OF GLOBAL ECOSYSTEM SERVICES USING THE GUMBO MODEL. (R827169)

    EPA Science Inventory

    A global unified metamodel of the biosphere (GUMBO) was developed to simulate the integrated earth system and assess the dynamics and values of ecosystem services. It is a `metamodel' in that it represents a synthesis and a simplification of several existing dynamic gl...

  8. An integrated, open-source set of tools for urban vulnerability monitoring from Earth observation data

    NASA Astrophysics Data System (ADS)

    De Vecchi, Daniele; Harb, Mostapha; Dell'Acqua, Fabio; Aurelio Galeazzo, Daniel

    2015-04-01

    Aim: The paper introduces an integrated set of open-source tools designed to process medium and high-resolution imagery with the aim to extract vulnerability indicators [1]. Problem: In the context of risk monitoring [2], a series of vulnerability proxies can be defined, such as the extension of a built-up area or buildings regularity [3]. Different open-source C and Python libraries are already available for image processing and geospatial information (e.g. OrfeoToolbox, OpenCV and GDAL). They include basic processing tools but not vulnerability-oriented workflows. Therefore, it is of significant importance to provide end-users with a set of tools capable to return information at a higher level. Solution: The proposed set of python algorithms is a combination of low-level image processing and geospatial information handling tools along with high-level workflows. In particular, two main products are released under the GPL license: source code, developers-oriented, and a QGIS plugin. These tools were produced within the SENSUM project framework (ended December 2014) where the main focus was on earthquake and landslide risk. Further development and maintenance is guaranteed by the decision to include them in the platform designed within the FP 7 RASOR project . Conclusion: With the lack of a unified software suite for vulnerability indicators extraction, the proposed solution can provide inputs for already available models like the Global Earthquake Model. The inclusion of the proposed set of algorithms within the RASOR platforms can guarantee support and enlarge the community of end-users. Keywords: Vulnerability monitoring, remote sensing, optical imagery, open-source software tools References [1] M. Harb, D. De Vecchi, F. Dell'Acqua, "Remote sensing-based vulnerability proxies in the EU FP7 project SENSUM", Symposium on earthquake and landslide risk in Central Asia and Caucasus: exploiting remote sensing and geo-spatial information management, 29-30th January 2014

  9. Core-shell Co/CoO Integrated on 3D Nitrogen Doped Reduced Graphene Oxide Aerogel as an Enhanced Electrocatalyst for the Oxygen Reduction Reaction

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Hou, Yuyang; Slade, Robert; Wang, Jiazhao; Shi, Dongqi; Wexler, David; Liu, Hua Kun

    2016-08-01

    Here, we demonstrate that Cobalt/cobalt oxide core-shell nanoparticles integrated on nitrogen-doped three-dimensional graphene architecture (Co/CoO-NG) were synthesized through a facile hydrothermal method following by heat treatment. The unique endurable porous structure could provide sufficient mass transfer channels and ample active sites on Co/CoO-NG to facilitate the catalytic reaction. The synthesized Co/CoO-NG was explored as an electrocatalyst for the oxygen reduction reaction, showing comparable oxygen reduction performance with excellent methanol resistance and better durability compared with Pt/C.

  10. On purpose in science, conservation and government. The functional integrity of the earth is at issue not biodiversity.

    PubMed

    Woodwell, George M

    2002-08-01

    of the integrity of function of landscapes (and waterbodies). Emphasis falls on forests in the normally naturally forested parts of the earth because forests are so large in area globally and have such a large influence on virtually every aspect of environment. Functional integrity requires structural integrity over 85% or more of the naturally forested zone in most areas. It also requires objective measurement and definition by the scientific community. Suddenly, conservation has become, not the preservation of biodiversity, honorable as that may be, but the preservation of the functional integrity of the human environment. That purpose is the central purpose that we assign to the governments that we establish in democracies to define and defend the public interest. It is past time for the scientific and conservation communities to recognize the urgency of this transition, join in defining competent new objectives for conservation, and to convey to the public the urgency of the need for governmental responsibility in protecting the public interest in a habitable biosphere.

  11. On purpose in science, conservation and government. The functional integrity of the earth is at issue not biodiversity.

    PubMed

    Woodwell, George M

    2002-08-01

    of the integrity of function of landscapes (and waterbodies). Emphasis falls on forests in the normally naturally forested parts of the earth because forests are so large in area globally and have such a large influence on virtually every aspect of environment. Functional integrity requires structural integrity over 85% or more of the naturally forested zone in most areas. It also requires objective measurement and definition by the scientific community. Suddenly, conservation has become, not the preservation of biodiversity, honorable as that may be, but the preservation of the functional integrity of the human environment. That purpose is the central purpose that we assign to the governments that we establish in democracies to define and defend the public interest. It is past time for the scientific and conservation communities to recognize the urgency of this transition, join in defining competent new objectives for conservation, and to convey to the public the urgency of the need for governmental responsibility in protecting the public interest in a habitable biosphere. PMID:12374052

  12. Earth: Earth Science and Health

    NASA Technical Reports Server (NTRS)

    Maynard, Nancy G.

    2001-01-01

    A major new NASA initiative on environmental change and health has been established to promote the application of Earth science remote sensing data, information, observations, and technologies to issues of human health. NASA's Earth Sciences suite of Earth observing instruments are now providing improved observations science, data, and advanced technologies about the Earth's land, atmosphere, and oceans. These new space-based resources are being combined with other agency and university resources, data integration and fusion technologies, geographic information systems (GIS), and the spectrum of tools available from the public health community, making it possible to better understand how the environment and climate are linked to specific diseases, to improve outbreak prediction, and to minimize disease risk. This presentation is an overview of NASA's tools, capabilities, and research advances in this initiative.

  13. Google Earth as a Vehicle to Integrating Multiple Layers of Environmental Satellite Data for Weather and Science Applications

    NASA Astrophysics Data System (ADS)

    Turk, F. J.; Miller, S. D.

    2007-12-01

    One of the main challenges facing current and future environmental satellite systems (e.g, the future National Polar Orbiting Environmental Satellite System (NPOESS)) is reaching and entraining the diverse user community via communication of how these systems address their particular needs. A necessary element to meeting this challenge is effective data visualization: facilitating the display, animation and layering of multiple satellite imaging and sounding sensors (providing complementary information) in a user-friendly and intuitive fashion. In light of the fact that these data are rapidly making their way into the classroom owing to efficient and timely data archival systems and dissemination over the Internet, there is a golden opportunity to leverage existing technology to introduce environmental science to wide spectrum of users. Google Earth's simplified interface and underlying markup language enables access to detailed global geographic information, and contains features which are both desirable and advantageous for geo-referencing and combining a wide range of environmental satellite data types. Since these satellite data are available with a variety of horizontal spatial resolutions (tens of km down to hundreds of meters), the imagery can be sub-setted (tiled) at a very small size. This allows low-bandwidth users to efficiently view and animate a sequence of imagery while zoomed out from the surface, whereas high-bandwidth users can efficiently zoom into the finest image resolution when viewing fine-scale phenomena such as fires, volcanic activity, as well as the details of meteorological phenomena such as hurricanes, rainfall, lightning, winds, etc. Dynamically updated network links allow for near real-time updates such that these data can be integrated with other Earth-hosted applications and exploited not only in the teaching environment, but also for operational users in the government and private industry sectors. To conceptualize how environmental

  14. Photoluminescence properties of rare-earth-doped (Er³⁺,Yb³⁺) Y₂O₃ nanophosphors by a combustion synthesis method.

    PubMed

    Kaur, Manmeet; Bisen, D P; Brahme, N; Singh, Prabhjot; Sahu, I P

    2016-05-01

    In this work, we report the synthesis of Y2O3:Er(3+), Y2O3:Yb(3+) and Y2O3:Er(3+),Yb(3+) nanophosphors by the combustion synthesis method using urea as fuel. The doping agents were incorporated in the form of erbium nitrate and ytterbium nitrate. X-Ray diffraction (XRD) patterns revealed that the synthesized particles have a body-centered cubic structure with space group Ia-3. The photoluminescence (PL) properties were investigated after UV and infrared irradiation at room temperature. A strong characteristic emission of Er(3+) and Yb(3+) ions was identified, and the influence of doping concentration on the PL properties was systematically studied. Energy transfer from Yb(3+) to Er(3+) ions was observed in Y2O3 nanophosphors. The obtained result may be useful in potential applications such as bioimaging.

  15. Earth materials and earth dynamics

    SciTech Connect

    Bennett, K; Shankland, T.

    2000-11-01

    In the project ''Earth Materials and Earth Dynamics'' we linked fundamental and exploratory, experimental, theoretical, and computational research programs to shed light on the current and past states of the dynamic Earth. Our objective was to combine different geological, geochemical, geophysical, and materials science analyses with numerical techniques to illuminate active processes in the Earth. These processes include fluid-rock interactions that form and modify the lithosphere, non-linear wave attenuations in rocks that drive plate tectonics and perturb the earth's surface, dynamic recrystallization of olivine that deforms the upper mantle, development of texture in high-pressure olivine polymorphs that create anisotropic velocity regions in the convecting upper mantle and transition zone, and the intense chemical reactions between the mantle and core. We measured physical properties such as texture and nonlinear elasticity, equation of states at simultaneous pressures and temperatures, magnetic spins and bonding, chemical permeability, and thermal-chemical feedback to better characterize earth materials. We artificially generated seismic waves, numerically modeled fluid flow and transport in rock systems and modified polycrystal plasticity theory to interpret measured physical properties and integrate them into our understanding of the Earth. This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

  16. Tin oxide thick film by doping rare earth for detecting traces of CO{sub 2}: Operating in oxygen-free atmosphere

    SciTech Connect

    Xiong, Ya; Zhang, Guozhu; Zhang, Shunping; Zeng, Dawen; Xie, Changsheng

    2014-04-01

    Highlights: • La, Gd, and Lu doped SnO{sub 2} with their sensing properties toward CO{sub 2} were compared. • The microstructures of SnO{sub 2}-based nanoparticles were elaborately characterized. • La-SnO{sub 2} thick film shows superior response toward trace ppm CO{sub 2}. • Our sensing material can be recommended to employ in oxygen-free environment. - Abstract: SnO{sub 2} thick films doped with atomic ratios ranging from 0 up to 8 at.% La, 8 at.% Gd, 8 at.% Lu were fabricated, respectively, via hydrothermal and impregnation methods. The crystal phase, morphology, and chemical composition of the SnO{sub 2}-based nanoparticles were characterized by XRD, FE-SEM, EDX, HRTEM and XPS. Sensing properties of La-SnO{sub 2}, Gd-SnO{sub 2}, Lu-SnO{sub 2} films, as well as the pure SnO{sub 2} film, were analyzed toward CO{sub 2} in the absence of O{sub 2}. It was found that the optimal doping element was La and the best doping ratio was 4 at.%. The maximum response appeared at an operating temperature of 250 °C, on which condition the 4 at.% La-SnO{sub 2} exhibited a remarkable improvement of response from 5.12 to 29.8 when increasing CO{sub 2} concentration from 50 to 500 ppm. Furthermore, the working mechanism underlying such enhancement in CO{sub 2}-sensing functions by La additive in the absence of O{sub 2} was proposed and discussed.

  17. Rare-earth-ion-doped ultra-narrow-linewidth lasers on a silicon chip and applications to intra-laser-cavity optical sensing

    NASA Astrophysics Data System (ADS)

    Bernhardi, E. H.; de Ridder, R. M.; Wörhoff, K.; Pollnau, M.

    2013-03-01

    We report on diode-pumped distributed-feedback (DFB) and distributed-Bragg-reflector (DBR) channel waveguide lasers in Er-doped and Yb-doped Al2O3 on standard thermally oxidized silicon substrates. Uniform surface-relief Bragg gratings were patterned by laser-interference lithography and etched into the SiO2 top cladding. The maximum grating reflectivity exceeded 99%. Monolithic DFB and DBR cavities with Q-factors of up to 1.35×106 were realized. The Erdoped DFB laser delivered 3 mW of output power with a slope efficiency of 41% versus absorbed pump power. Singlelongitudinal- mode operation at a wavelength of 1545.2 nm was achieved with an emission line width of 1.70 0.58 kHz, corresponding to a laser Q-factor of 1.14×1011. Yb-doped DFB and DBR lasers were demonstrated at wavelengths near 1020 nm with output powers of 55 mW and a slope efficiency of 67% versus launched pump power. An Yb-doped dualwavelength laser was achieved based on the optical resonances induced by two local phase shifts in the DFB structure. A stable microwave signal at ~15 GHz with a -3-dB width of 9 kHz and a long-term frequency stability of +/- 2.5 MHz was created via the heterodyne photo-detection of the two laser wavelengths. By measuring changes in the microwave beat signal as the intra-cavity evanescent laser field interacts with micro-particles on the waveguide surface, we achieved real-time detection and accurate size measurement of single micro-particles with diameters ranging between 1 μm and 20 μm, which represents the typical size of many fungal and bacterial pathogens. A limit of detection of ~500 nm was deduced.

  18. Space-Based Erbium-Doped Fiber Amplifier Transmitters for Coherent, Ranging, 3D-Imaging, Altimetry, Topology, and Carbon Dioxide Lidar and Earth and Planetary Optical Laser Communications

    NASA Astrophysics Data System (ADS)

    Storm, Mark; Engin, Doruk; Mathason, Brian; Utano, Rich; Gupta, Shantanu

    2016-06-01

    This paper describes Fibertek, Inc.'s progress in developing space-qualified Erbium-doped fiber amplifier (EDFA) transmitters for laser communications and ranging/topology, and CO2 integrated path differential absorption (IPDA) lidar. High peak power (1 kW) and 6 W of average power supporting multiple communications formats has been demonstrated with 17% efficiency in a compact 3 kg package. The unit has been tested to Technology Readiness Level (TRL) 6 standards. A 20 W EDFA suitable for CO2 lidar has been demonstrated with ~14% efficiency (electrical to optical [e-o]) and its performance optimized for 1571 nm operation.

  19. The key role of Satellite Laser Ranging towards the integrated estimation of geometry, rotation and gravitational field of the Earth

    NASA Astrophysics Data System (ADS)

    Blossfeld, Mathis

    2015-01-01

    In 2007, the Global Geodetic Observing System (GGOS) was installed as a full component of the International Association of Geodesy (IAG). One primary goal of GGOS is the integration of geometric and gravimetric observation techniques to estimate consistent geodetic-geophysical parameters. Thereby, GGOS is based on the data and services of the IAG. Besides the combination of different geodetic techniques, also the common estimation of the station coordinates (TRF), Earth Orientation Parameters (EOP) and coefficients of the Earth's gravitational field (Stokes coefficients) is necessary in order to reach this goal. However, the combination of all geometric and gravimetric observation techniques is not yet fully realized. A major step towards the GGOS idea of parameter integration would be the understanding of the existing correlations between the above mentioned fundamental geodetic parameter groups. This topic is the major objective of this thesis. One possibility to study the interactions is the use of Satellite Laser Ranging (SLR) in an intertechnique combination with Global Navigation Satellite Systems (GNSS) and Very Long Baseline Interferometry (VLBI) or the intra-technique combination of multiple SLR-tracked satellites. SLR plays a key role in this thesis since it is the unique technique which is sensitive to all parameter groups and allows an integrated parameter estimation with very high accuracy. The present work is based on five first-author publications which are supplemented by four co-author publications. In this framework, for the first time an extensive discussion of a refined global Terrestrial Reference Frame (TRF) estimation procedure, the estimation of so-called Epoch Reference Frames (ERFs) is presented. In contrast to the conventional linear station motion model, the ERFs provide frequently estimated station coordinates and Earth Orientation Parameters (EOP) which allow to approximate not modeled non-linear station motions very accurately

  20. Effects of some rare earth and carbonate-based co-dopants on structural and electrical properties of samarium doped ceria (SDC) electrolytes for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Anwar, Mustafa; Khan, Zuhair S.; Mustafa, Kamal; Rana, Akmal

    2015-09-01

    In the present study, samarium doped ceria (SDC) and SDC-based composite with the addition of K2CO3 were prepared by co-precipitation route and effects of pH of the solution and calcination temperature on microstructure of SDC and SDC-K2CO3, respectively, were investigated. Furthermore, experimentation was performed to investigate into the ionic conductivity of pure SDC by co-doping with yttrium i.e., YSDC, XRD and SEM studies show that the crystallite size and particle size of SDC increases with the increase in pH. The SEM images of all the samples of SDC synthesized at different pH values showed the irregular shaped and dispersed particles. SDC-K2CO3 was calcined at 600∘C, 700∘C and 800∘C for 4 h and XRD results showed that crystallite size increases while lattice strain, decreases with the increase in calcination temperature and no peaks were detected for K2CO3 as it is present in an amorphous form. The ionic conductivity of the electrolytes increases with the increase in temperature and SDC-K2CO3 shows the highest value of ionic conductivity as compared to SDC and YSDC. Chemical compatibility tests were performed between the co-doped electrolyte and lithiated NiO cathode at high temperature. It revealed that the couple could be used up to the temperature of 700∘C.

  1. Integrated 3D porous C-MoS2/nitrogen-doped graphene electrode for high capacity and prolonged stability lithium storage

    NASA Astrophysics Data System (ADS)

    Xie, D.; Tang, W. J.; Xia, X. H.; Wang, D. H.; Zhou, D.; Shi, F.; Wang, X. L.; Gu, C. D.; Tu, J. P.

    2015-11-01

    Scrupulous design and fabrication of advanced anode materials are of great importance for developing high-performance lithium ion batteries. Herein, we report a facile strategy for construction of free-standing and free-binder 3D porous carbon coated MoS2/nitrogen-doped graphene (C-MoS2/N-G) integrated electrode via a hydrothermal-induced self-assembly process. The preformed carbon coated MoS2 is strongly anchored on the porous nitrogen-doped graphene aerogel architecture. As an anode for lithium ion batteries, the C-MoS2/N-G electrode delivers a high first discharge capacity of 1600 mAh g-1 and maintains 900 mAh g-1 after 500 cycles at a current density of 200 mA g-1. Impressively, superior high-rate capability is achieved for the C-MoS2/N-G with a reversible capacity of 500 mAh g-1 at a high current density of 4000 mA g-1. Furthermore, the lithium storage mechanism of the obtained integrated electrode is investigated by ex-situ X-ray photoelectron spectroscopy and transmission electron microscopy in detail.

  2. The EOS Aqua/Aura Experience: Lessons Learned on Design, Integration, and Test of Earth-Observing Satellites

    NASA Technical Reports Server (NTRS)

    Nosek, Thomas P.

    2004-01-01

    NASA and NOAA earth observing satellite programs are flying a number of sophisticated scientific instruments which collect data on many phenomena and parameters of the earth's environment. The NASA Earth Observing System (EOS) Program originated the EOS Common Bus approach, which featured two spacecraft (Aqua and Aura) of virtually identical design but with completely different instruments. Significant savings were obtained by the Common Bus approach and these lessons learned are presented as information for future program requiring multiple busses for new diversified instruments with increased capabilities for acquiring earth environmental data volume, accuracy, and type.

  3. Information Technology Infusion Case Study: Integrating Google Earth(Trademark) into the A-Train Data Depot

    NASA Technical Reports Server (NTRS)

    Smith, Peter; Kempler, Steven; Leptoukh, Gregory; Chen, Aijun

    2010-01-01

    This poster paper represents the NASA funded project that was to employ the latest three dimensional visualization technology to explore and provide direct data access to heterogeneous A-Train datasets. Google Earth (tm) provides foundation for organizing, visualizing, publishing and synergizing Earth science data .

  4. Analog Testing of Operations Concepts for Integration of an Earth-Based Science Team During Human Exploration of Mars

    NASA Technical Reports Server (NTRS)

    Chappell, Steven P.; Beaton, Kara H.; Graff, Trevor; Newton, Carolyn; Abercromby, Andrew F.; Gernhardt, Michael L.

    2017-01-01

    NASA Extreme Environment Mission Operations (NEEMO) is an underwater spaceflight analog that allows a true mission-like operational environment and uses buoyancy effects and added weight to simulate different gravity levels. A mission was undertaken in 2016, NEEMO 21. The mission was performed at the Aquarius undersea research habitat. During the mission, the effects of varying operations concepts on representative communication latencies associated with Mars missions were studied. Six subjects were weighed out to simulate near-zero or partial gravity and evaluated different operations concepts for integration and management of a simulated Earth-based science team (ST) to provide input and direction during exploration activities. Exploration traverses were planned in advance based on precursor data collected. Subjects completed science-related tasks including pre-sampling surveys and marine science-based sampling as a portion of their tasks on saturation dives up to 4 hours in duration that were to simulate extravehicular activity (EVA) on Mars. A one-way communication latency of 15 minutes between space and mission control was simulated throughout the missions. Objective data included task completion times, total EVA times, crew idle time, translation time, SBT assimilation time (defined as time available for ST to discuss data/imagery after it has been collected, in addition to the time taken to watch imagery and listen to audio streaming over latency). Subjective data included acceptability, simulation quality, capability assessment ratings, and comments. Results were collected and will be presented on the acceptability of the operations concepts studied and which capabilities are the most enabling/enhancing in the operations concept. Discussion is presented on the importance of designing EVA timelines to account for the length of the task, level of interaction with the ground that is required/desired, and communication latency.

  5. The Use of the Integrated Medical Model for Forecasting and Mitigating Medical Risks for a Near-Earth Asteroid Mission

    NASA Technical Reports Server (NTRS)

    Kerstman, Eric; Saile, Lynn; Freire de Carvalho, Mary; Myers, Jerry; Walton, Marlei; Butler, Douglas; Lopez, Vilma

    2011-01-01

    Introduction The Integrated Medical Model (IMM) is a decision support tool that is useful to space flight mission managers and medical system designers in assessing risks and optimizing medical systems. The IMM employs an evidence-based, probabilistic risk assessment (PRA) approach within the operational constraints of space flight. Methods Stochastic computational methods are used to forecast probability distributions of medical events, crew health metrics, medical resource utilization, and probability estimates of medical evacuation and loss of crew life. The IMM can also optimize medical kits within the constraints of mass and volume for specified missions. The IMM was used to forecast medical evacuation and loss of crew life probabilities, as well as crew health metrics for a near-earth asteroid (NEA) mission. An optimized medical kit for this mission was proposed based on the IMM simulation. Discussion The IMM can provide information to the space program regarding medical risks, including crew medical impairment, medical evacuation and loss of crew life. This information is valuable to mission managers and the space medicine community in assessing risk and developing mitigation strategies. Exploration missions such as NEA missions will have significant mass and volume constraints applied to the medical system. Appropriate allocation of medical resources will be critical to mission success. The IMM capability of optimizing medical systems based on specific crew and mission profiles will be advantageous to medical system designers. Conclusion The IMM is a decision support tool that can provide estimates of the impact of medical events on human space flight missions, such as crew impairment, evacuation, and loss of crew life. It can be used to support the development of mitigation strategies and to propose optimized medical systems for specified space flight missions. Learning Objectives The audience will learn how an evidence-based decision support tool can be

  6. On the formulation of gravitational potential difference between the GRACE satellites based on energy integral in Earth fixed frame

    NASA Astrophysics Data System (ADS)

    Zeng, Y. Y.; Guo, J. Y.; Shang, K.; Shum, C. K.; Yu, J. H.

    2015-09-01

    Two methods for computing gravitational potential difference (GPD) between the GRACE satellites using orbit data have been formulated based on energy integral; one in geocentric inertial frame (GIF) and another in Earth fixed frame (EFF). Here we present a rigorous theoretical formulation in EFF with particular emphasis on necessary approximations, provide a computational approach to mitigate the approximations to negligible level, and verify our approach using simulations. We conclude that a term neglected or ignored in all former work without verification should be retained. In our simulations, 2 cycle per revolution (CPR) errors are present in the GPD computed using our formulation, and empirical removal of the 2 CPR and lower frequency errors can improve the precisions of Stokes coefficients (SCs) of degree 3 and above by 1-2 orders of magnitudes. This is despite of the fact that the result without removing these errors is already accurate enough. Furthermore, the relation between data errors and their influences on GPD is analysed, and a formal examination is made on the possible precision that real GRACE data may attain. The result of removing 2 CPR errors may imply that, if not taken care of properly, the values of SCs computed by means of the energy integral method using real GRACE data may be seriously corrupted by aliasing errors from possibly very large 2 CPR errors based on two facts: (1) errors of bar C_{2,0} manifest as 2 CPR errors in GPD and (2) errors of bar C_{2,0} in GRACE data-the differences between the CSR monthly values of bar C_{2,0} independently determined using GRACE and SLR are a reasonable measure of their magnitude-are very large. Our simulations show that, if 2 CPR errors in GPD vary from day to day as much as those corresponding to errors of bar C_{2,0} from month to month, the aliasing errors of degree 15 and above SCs computed using a month's GPD data may attain a level comparable to the magnitude of gravitational potential

  7. 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.

  8. Earth Abundant Iron-Rich N-Doped Graphene Based Spacer and Cavity Materials for Surface Plasmon-Coupled Emission Enhancements.

    PubMed

    Srinivasan, Venkatesh; Vernekar, Dnyanesh; Jaiswal, Garima; Jagadeesan, Dinesh; Ramamurthy, Sai Sathish

    2016-05-18

    We demonstrate for the first time the use of Fe-based nanoparticles on N-doped graphene as spacer and cavity materials and study their plasmonic effect on the spontaneous emission of a radiating dipole. Fe-C-MF was produced by pyrolizing FeOOH and melamine formaldehyde precursor on graphene, while Fe-C-PH was produced by pyrolizing the Fe-phenanthroline complex on graphene. The use of the Fe-C-MF composite consisting of Fe-rich crystalline phases supported on N-doped graphene presented a spacer material with 116-fold fluorescence enhancements. On the other hand, the Fe-C-PH/Ag based cavity resulted in an 82-fold enhancement in Surface Plasmon-Coupled Emission (SPCE), with high directionality and polarization of Rhodamine 6G (Rh6G) emission owing to Casimir and Purcell effects. The use of a mobile phone as a cost-effective fluorescence detection device in the present work opens up a flexible perspective for the study of different nanomaterials as tunable substrates in cavity mode and spacer applications. PMID:27128348

  9. Large research infrastructure for Earth-Ocean Science: Challenges of multidisciplinary integration across hardware, software, and people networks

    NASA Astrophysics Data System (ADS)

    Best, M.; Barnes, C. R.; Johnson, F.; Pautet, L.; Pirenne, B.; Founding Scientists Of Neptune Canada

    2010-12-01

    NEPTUNE Canada is operating a regional cabled ocean observatory across the northern Juan de Fuca Plate in the northeastern Pacific. Installation of the first suite of instruments and connectivity equipment was completed in 2009, so this system now provides the continuous power and bandwidth to collect integrated data on physical, chemical, geological, and biological gradients at temporal resolutions relevant to the dynamics of the earth-ocean system. The building of this facility integrates hardware, software, and people networks. Hardware progress to date includes: installation of the 800km powered fiber-optic backbone in the Fall of 2007; development of Nodes and Junction Boxes; acquisition/development and testing of Instruments; development of mobile instrument platforms such as a) a Vertical Profiler and b) a Crawler (University of Bremmen); and integration of over a thousand components into an operating subsea sensor system. Nodes, extension cables, junction boxes, and instruments were installed at 4 out of 5 locations in 2009; the fifth Node is instrumented in September 2010. In parallel, software and hardware systems are acquiring, archiving, and delivering the continuous real-time data through the internet to the world - already many terabytes of data. A web environment (Oceans 2.0) to combine this data access with analysis and visualization, collaborative tools, interoperability, and instrument control is being released. Finally, a network of scientists and technicians are contributing to the process in every phase, and data users already number in the thousands. Initial experiments were planned through a series of workshops and international proposal competitions. At inshore Folger Passage, Barkley Sound, understanding controls on biological productivity help evaluate the effects that marine processes have on fish and marine mammals. Experiments around Barkley Canyon allow quantification of changes in biological and chemical activity associated with

  10. Supramolecular recognition control of polyethylene glycol modified N-doped graphene quantum dots: tunable selectivity for alkali and alkaline-earth metal ions.

    PubMed

    Yang, Siwei; Sun, Jing; Zhu, Chong; He, Peng; Peng, Zheng; Ding, Guqiao

    2016-02-01

    The graphene quantum dot based fluorescent probe community needs unambiguous evidence about the control on the ion selectivity. In this paper, polyethylene glycol modified N-doped graphene quantum dots (PN-GQDs) were synthesized by alkylation reaction between graphene quantum dots and organic halides. We demonstrate the tunable selectivity and sensitivity by controlling the supramolecular recognition through the length and the end group size of the polyether chain on PN-GQDs. The relationship formulae between the selectivity/detection limit and polyether chains are experimentally deduced. The polyether chain length determines the interaction between the PN-GQDs and ions with different ratios of charge to radius, which in turn leads to a good selectivity control. Meanwhile the detection limit shows an exponential growth with the size of end groups of the polyether chain. The PN-GQDs can be used as ultrasensitive and selective fluorescent probes for Li(+), Na(+), K(+), Mg(2+), Ca(2+) and Sr(2+), respectively. PMID:26730814

  11. Why are the Tcs so high in rare-earth doped CaFe2As2 single crystals and ultrathin FeSe epi-films?

    NASA Astrophysics Data System (ADS)

    Chu, C. W.

    2015-03-01

    Recent reports of non-bulk superconductivity with unexpectedly high onset-Tcs up to 49 K in the Pr-doped CaFe2As2 [(Ca,Pr)122] single crystals and up to 100 K in one-unit-cell (1UC) FeSe epi-films, respectively, offer an unusual opportunity to seek an answer to the question posed in the title. Through systematic compositional, structural, resistive, and magnetic investigations on (Ca,R)122 single crystals with R = La, Ce, Pr, and Nd, we have observed a doping-level-independent Tc, a large magnetic anisotropy, and the existence of mesoscopic-2D structures in these crystals, thus providing evidence consistent with the proposed interface-enhanced Tc in these naturally assembled Fe-based superconductors. Similar resistive and magnetic measurements were also made on the 1-4UC FeSe ultra thin epi-films. We have detected a Meissner state below 1 Oe with extensive weak-links up to ~ 20 K, unconnected small superconducting patches up to ~ 40 K, and an unusual dispersion of diamagnetic moment with frequency up to 80 K. The unusual frequency dependences of the diamagnetic moment observed in the films at different temperature ranges suggest that collective excitations of electron and/or spin nature may exist in the FeSe films below 20 K and 40-80 K. The experimental results will be presented and the implications discussed. Collaborators: Liangzi Deng, Bing Lv, Fengyan Wei, and Yu-Yi Xue, University of Houston; Li-Li Wang, Xu-Cun Ma, and Qi-Kun Xue, Tsinghua University, Beijing.

  12. Defect Clustering and Nano-phase Structure Characterization of Multicomponent Rare Earth-Oxide-Doped Zirconia-Yttria Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Chen, Yuan L.; Miller, Robert A.

    2004-01-01

    Advanced thermal barrier coatings (TBCs) have been developed by incorporating multicomponent rare earth oxide dopants into zirconia-based thermal barrier coatings to promote the creation of the thermodynamically stable, immobile oxide defect clusters and/or nanophases within the coating systems. In this paper, the defect clusters, induced by Nd, Gd, and Yb rare earth dopants in the zirconia-yttria thermal barrier coatings, were characterized by high-resolution transmission electron microscopy (TEM). The TEM lattice imaging, selected area diffraction (SAD), and electron energy-loss spectroscopy (EELS) analyses demonstrated that the extensive nanoscale rare earth dopant segregation exists in the plasma-sprayed and electron-physical-vapor-deposited (EB PVD) thermal barrier coatings. The nanoscale concentration heterogeneity and the resulting large lattice distortion promoted the formation of parallel and rotational defective lattice clusters in the coating systems. The presence of the 5-to 100-nm-sized defect clusters and nanophases is believed to be responsible for the significant reduction of thermal conductivity, improved sintering resistance, and long-term high temperature stability of the advanced thermal barrier coating systems.

  13. Energies of 4f^N and 4f^N-15d States Relative to Host Bands in Rare-earth-doped Fluorides

    NASA Astrophysics Data System (ADS)

    Thiel, C. W.; Joubert, M.-F.; Tkachuk, A.

    2005-03-01

    Energies of 4f^N states relative to crystal band states were measured for rare-earth ions in the optical host materials LiYF4, Na0.4Y0.6F2.2, and LaF3 using x-ray photoemission spectroscopy. Spectra were modeled to determine the valence band maximum and 4f^ electron binding energies in each material. These results were combined with 4f^N to 4f^N-15d transition energies to determine 5d binding energies for the lowest levels of excited 4f^N-15d configurations. While 4f^N ground-state energies vary within several eV of the valence band maximum for different rare-earth ions in each host, the lowest 4f^N-15d states have similar energies and are several eV below the bottom of the conduction band. A simple model accurately described 4f^N and 4f^N-15d binding energies across the entire series of rare-earth ions. These results improve the understanding of optical materials for lasers, phosphors, and spectral hole burning applications for optical signal processing and data storage.

  14. Integrating land management into Earth system models: the importance of land use transitions at sub-grid-scale

    NASA Astrophysics Data System (ADS)

    Pongratz, Julia; Wilkenskjeld, Stiig; Kloster, Silvia; Reick, Christian

    2014-05-01

    Recent studies indicate that changes in surface climate and carbon fluxes caused by land management (i.e., modifications of vegetation structure without changing the type of land cover) can be as large as those caused by land cover change. Further, such effects may occur on substantial areas: while about one quarter of the land surface has undergone land cover change, another fifty percent are managed. This calls for integration of management processes in Earth system models (ESMs). This integration increases the importance of awareness and agreement on how to diagnose effects of land use in ESMs to avoid additional model spread and thus unnecessary uncertainties in carbon budget estimates. Process understanding of management effects, their model implementation, as well as data availability on management type and extent pose challenges. In this respect, a significant step forward has been done in the framework of the current IPCC's CMIP5 simulations (Coupled Model Intercomparison Project Phase 5): The climate simulations were driven with the same harmonized land use dataset that, different from most datasets commonly used before, included information on two important types of management: wood harvest and shifting cultivation. However, these new aspects were employed by only part of the CMIP5 models, while most models continued to use the associated land cover maps. Here, we explore the consequences for the carbon cycle of including subgrid-scale land transformations ("gross transitions"), such as shifting cultivation, as example of the current state of implementation of land management in ESMs. Accounting for gross transitions is expected to increase land use emissions because it represents simultaneous clearing and regrowth of natural vegetation in different parts of the grid cell, reducing standing carbon stocks. This process cannot be captured by prescribing land cover maps ("net transitions"). Using the MPI-ESM we find that ignoring gross transitions

  15. The DataTools Professional Development Program: Supporting the Integration of Data and Analysis in Middle School Earth Science Programs

    NASA Astrophysics Data System (ADS)

    Haddad, N.; Ledley, T. S.; McAuliffe, C.; Dahlman, L.

    2007-12-01

    TERC's professional development program Tools for Data Analysis in the Middle School Classroom (a.k.a. DataTools) addresses the need for well-prepared Earth science teachers by helping change the practice of those who are "approaching Earth sciences from a traditional perspective", and 2) those who are "challenged by the need to link research with classroom experiences". The DataTools program addresses this need via a yearlong professional development program that helps middle school teachers develop competence in locating and downloading Web-based Earth science data, and visualizing and analyzing that data using a suite of analysis tools. Leveraging the resources and techniques of the Earth Exploration Toolbook, the DataTools team promotes the practice of having students attempt to answer scientific questions by examining and analyzing relevant data using tools and fostering dialog as they evaluate and try to make sense of their results. In this session, we will describe the DataTools professional development program and the Earth Exploration Toolbook, and will summarize what we have learned during the first two years of this three-year program. We will also share some of the work that teachers have used with their students during the first two years of the program.

  16. Recent Progresses in Incorporating Human Land-Water Management into Global Land Surface Models Toward Their Integration into Earth System Models

    NASA Technical Reports Server (NTRS)

    Pokhrel, Yadu N.; Hanasaki, Naota; Wada, Yoshihide; Kim, Hyungjun

    2016-01-01

    The global water cycle has been profoundly affected by human land-water management. As the changes in the water cycle on land can affect the functioning of a wide range of biophysical and biogeochemical processes of the Earth system, it is essential to represent human land-water management in Earth system models (ESMs). During the recent past, noteworthy progress has been made in large-scale modeling of human impacts on the water cycle but sufficient advancements have not yet been made in integrating the newly developed schemes into ESMs. This study reviews the progresses made in incorporating human factors in large-scale hydrological models and their integration into ESMs. The study focuses primarily on the recent advancements and existing challenges in incorporating human impacts in global land surface models (LSMs) as a way forward to the development of ESMs with humans as integral components, but a brief review of global hydrological models (GHMs) is also provided. The study begins with the general overview of human impacts on the water cycle. Then, the algorithms currently employed to represent irrigation, reservoir operation, and groundwater pumping are discussed. Next, methodological deficiencies in current modeling approaches and existing challenges are identified. Furthermore, light is shed on the sources of uncertainties associated with model parameterizations, grid resolution, and datasets used for forcing and validation. Finally, representing human land-water management in LSMs is highlighted as an important research direction toward developing integrated models using ESM frameworks for the holistic study of human-water interactions within the Earths system.

  17. Preparation and Characterization of Yttrium Hydroxide and Oxide Doped with Rare Earth Ions (Eu3+, Tb3+) Nano One-dimensional

    NASA Astrophysics Data System (ADS)

    Giang, Lam Thi Kieu; Anh, Tran Kim; Marciniak, Lukasz; Hreniak, Dariusz; Strek, Wieslaw; Lojkowski, Witold; Minh, Le Quoc

    The one-dimensional (1D) crystalline nanostructures of Y(OH)3:Eu/Tb have been synthesized using softemplate method at temperature range of 180 - 200 °C for 24 h. The studies by Field Emission Scanning Electron Microscopy (FESEM) have been determined that the outer and interior hollow diameter of Y(OH)3:Eu/Tb nanotubes was obtained range from 150 to 500 nm and 100 to 300 nm, respectively and of the length up to several micrometers, respectively. The Y2O3:Eu/Tb nanorod/tubes have been obtained from Y(OH)3:Eu/Tb counterparts by crucial annealing. The Xray diffraction (XRD) patterns indicated that the Y(OH)3:Eu/Tb and Y2O3:Eu/Tb nanorods and nanotubes obtained has hexagonal and cubic phase with high crystaline. The luminescence and excitation properties of Y(OH)3:Eu/Tb and Y2O3:Eu/Tb nanorods and nanotubes were investigated in details. It found that crystal form and nanomorphology of Y(OH)3 and Y2O3 have played a great role on the emission properties of the doped Eu3+ ions.

  18. Stabilisation of Fe2O3-rich Perovskite Nanophase in Epitaxial Rare-earth Doped BiFeO3 Films

    PubMed Central

    Zhang, Huairuo; Reaney, Ian M.; Marincel, Daniel M.; Trolier-McKinstry, Susan; Ramasse, Quentin M.; MacLaren, Ian; Findlay, Scott D.; Fraleigh, Robert D.; Ross, Ian M.; Hu, Shunbo; Ren, Wei; Mark Rainforth, W.

    2015-01-01

    Researchers have demonstrated that BiFeO3 exhibits ferroelectric hysteresis but none have shown a strong ferromagnetic response in either bulk or thin film without significant structural or compositional modification. When remanent magnetisations are observed in BiFeO3 based thin films, iron oxide second phases are often detected. Using aberration-corrected scanning transmission electron microscopy, atomic resolution electron energy loss spectrum-mapping and quantitative energy dispersive X-ray spectroscopy analysis, we reveal the existence of a new Fe2O3-rich perovskite nanophase, with an approximate formula (Fe0.6Bi0.25Nd0.15)3+ Fe3+O3, formed within epitaxial Ti and Nd doped BiFeO3 perovskite films grown by pulsed laser deposition. The incorporation of Nd and Bi ions on the A-site and coherent growth with the matrix stabilise the Fe2O3-rich perovskite phase and preliminary density functional theory calculations suggest that it should have a ferrimagnetic response. Perovskite-structured Fe2O3 has been reported previously but never conclusively proven when fabricated at high-pressure high-temperature. This work suggests the incorporation of large A-site species may help stabilise perovskite-structured Fe2O3. This finding is therefore significant not only to the thin film but also to the high-pressure community. PMID:26272264

  19. Stabilisation of Fe2O3-rich Perovskite Nanophase in Epitaxial Rare-earth Doped BiFeO3 Films.

    PubMed

    Zhang, Huairuo; Reaney, Ian M; Marincel, Daniel M; Trolier-McKinstry, Susan; Ramasse, Quentin M; MacLaren, Ian; Findlay, Scott D; Fraleigh, Robert D; Ross, Ian M; Hu, Shunbo; Ren, Wei; Rainforth, W Mark

    2015-08-14

    Researchers have demonstrated that BiFeO3 exhibits ferroelectric hysteresis but none have shown a strong ferromagnetic response in either bulk or thin film without significant structural or compositional modification. When remanent magnetisations are observed in BiFeO3 based thin films, iron oxide second phases are often detected. Using aberration-corrected scanning transmission electron microscopy, atomic resolution electron energy loss spectrum-mapping and quantitative energy dispersive X-ray spectroscopy analysis, we reveal the existence of a new Fe2O3-rich perovskite nanophase, with an approximate formula (Fe0.6Bi0.25Nd0.15)(3+) Fe(3+)O3, formed within epitaxial Ti and Nd doped BiFeO3 perovskite films grown by pulsed laser deposition. The incorporation of Nd and Bi ions on the A-site and coherent growth with the matrix stabilise the Fe2O3-rich perovskite phase and preliminary density functional theory calculations suggest that it should have a ferrimagnetic response. Perovskite-structured Fe2O3 has been reported previously but never conclusively proven when fabricated at high-pressure high-temperature. This work suggests the incorporation of large A-site species may help stabilise perovskite-structured Fe2O3. This finding is therefore significant not only to the thin film but also to the high-pressure community.

  20. Stabilisation of Fe2O3-rich Perovskite Nanophase in Epitaxial Rare-earth Doped BiFeO3 Films.

    PubMed

    Zhang, Huairuo; Reaney, Ian M; Marincel, Daniel M; Trolier-McKinstry, Susan; Ramasse, Quentin M; MacLaren, Ian; Findlay, Scott D; Fraleigh, Robert D; Ross, Ian M; Hu, Shunbo; Ren, Wei; Rainforth, W Mark

    2015-01-01

    Researchers have demonstrated that BiFeO3 exhibits ferroelectric hysteresis but none have shown a strong ferromagnetic response in either bulk or thin film without significant structural or compositional modification. When remanent magnetisations are observed in BiFeO3 based thin films, iron oxide second phases are often detected. Using aberration-corrected scanning transmission electron microscopy, atomic resolution electron energy loss spectrum-mapping and quantitative energy dispersive X-ray spectroscopy analysis, we reveal the existence of a new Fe2O3-rich perovskite nanophase, with an approximate formula (Fe0.6Bi0.25Nd0.15)(3+) Fe(3+)O3, formed within epitaxial Ti and Nd doped BiFeO3 perovskite films grown by pulsed laser deposition. The incorporation of Nd and Bi ions on the A-site and coherent growth with the matrix stabilise the Fe2O3-rich perovskite phase and preliminary density functional theory calculations suggest that it should have a ferrimagnetic response. Perovskite-structured Fe2O3 has been reported previously but never conclusively proven when fabricated at high-pressure high-temperature. This work suggests the incorporation of large A-site species may help stabilise perovskite-structured Fe2O3. This finding is therefore significant not only to the thin film but also to the high-pressure community. PMID:26272264

  1. High-Tc Superconductivity and Raman Scattering Study of the phonon properties of electron doped (transition metal, rare-earth) - Oxygen-Free CaFeAsF and compared with RFeAsO system

    NASA Astrophysics Data System (ADS)

    Sasmal, Kalyan; Hadjiev, Viktor; Chu, C. W.(Paul)

    Quaternary CaFeAsF has ZrCuSiAs-type structure,(RO)δ+ layer in RFeAsO replaced by (CaF)δ+ layer,with tetragonal (P4/nmm)-orthorhombic (Cmma) phase transition at 134K,while magnetic order,SDW sets in at 114K. Partial replacement of Fe with Co/Ni is direct electron doping to (FeAs)δ+ layer.Tc ~15K in CaFe0.9Ni0.1AsF.Substitution of rare earth metal for alkaline earth metal suppresses anomaly in resistivity & induces superconductivity.Tc ~52K in Ca0.5Pr0.5FeAsF.Characterized by resistivity, susceptibility,XRD & EDX-SEM.Upper critical field estimated from magneto resistance.Bulk superconductivity proved by DC magnetization. Hall coefficient RH revealed hole-like charge carriers in parent compound CaFeAsF, while electron-type (RH in normal state is -Ve) for Ca0.5Pr0.5FeAsF.Evolution of Raman active phonons of Ca1-xPrxFeAsF measured with polarized Raman spectroscopy at room temperature from absurfaces of impurity-free microcrystals.Spectra exhibit sharp phonon lines on very weak electronic scattering background.Frequency and symmetry of Raman phonons involving out-of-plane atomic vibrations are found at 162.5 cm-1 (A1 g, Pr), 201 cm-1 (A1 g, As), 215.5 cm-1 (B1 g, Fe), 265 cm-1 (Eg, Fe) and 334 cm-1 (B1 g, F) for Ca0.5Pr0.5FeAsF.Observations are compared with RFeAsO unconventional superconductors also possibly related to magnetic fluctuations

  2. Synthesis and characterization of visible emission from rare-earth doped aluminum nitride, gallium nitride and gallium aluminum nitride powders and thin films

    NASA Astrophysics Data System (ADS)

    Tao, Jonathan Huai-Tse

    A three-step solution-based process had been used synthesize powders of GaN, AlN and their alloys. The complete solid solubility and tunable nature of these nitride band gaps in the visible spectrum were the motivation of these studies due to their application in solid state lighting. Energy dispersive X-ray spectroscopy confirmed the reduction in oxygen content for the GaN powders to as low as 4 atom % with an 8 % oxygen to nitrogen ratio. Relative to commercial GaN powders, the bandedge of the powders synthesized by such approach also shifted to higher energy, which indicated fewer defects, as observed from reflectance measurements. Inspired by the use of rare-earth elements as color emitters in fluorescent lamp phosphors, these elements were also used as activators in our nitride material. Visible emission was demonstrated through photoluminescence measurements in AlN powders activated with rare-earth elements Eu3+, Tb3+, Tm3+. These ions showed emission in the red, green and blue regions of the visible spectrum, respectively. Eu3+ and Tb3+ co-activation was also observed in an AlN sample that indicated successful energy transfer from the host to sensitizer, and subsequently to another activator. Tb3+ emission was observed under cathodoluminescence in GaN powders synthesized by the same method, and a concentration study showed no effect of concentration quenching up to 8 atom %. Using the same source powder, a pulsed-laser deposited thin film was fabricated that showed both band gap emission and activator-related emission, suggesting a reduction of defects when the powders were deposited as thin films. Additionally, GaN:Tb3+ films were also fabricated using metallorganic vapor phase epitaxy using precursors with and without oxygen ligands. Tb3+ emission was only observed in the sample fabricated from the precursor with oxygen ligand, suggestion that oxygen may be required for effective rare earth luminescence. Finally, Ga1-xAl xN alloy powders (x=0.5) and Ga1-x

  3. Practicing ESD at School: Integration of Formal and Nonformal Education Methods Based on the Earth Charter (Belarusian Experience)

    ERIC Educational Resources Information Center

    Savelava, Sofia; Savelau, Dmitry; Cary, Marina Bakhnova

    2010-01-01

    The Earth Charter represents the philosophy and ethics necessary to create a new period of human civilization. Understanding and adoption of this new vision is the most important mission of education for sustainable development (ESD). This article argues that for successful implementation of ESD principles at school, the school education system…

  4. Chemical environment of rare earth ions in Ge{sub 28.125}Ga{sub 6.25}S{sub 65.625} glass-ceramics doped with Dy{sup 3+}

    SciTech Connect

    Wang, Rongping Yan, Kunlun; Luther-Davies, Barry; Zhang, Mingjie; Yang, Anping; Zhang, Bin; Shen, Xiang; Dai, Shixun; Yang, Xinyu; Yang, Zhiyong

    2015-10-19

    We have annealed Ge{sub 28.125}Ga{sub 6.25}S{sub 65.625} glasses doped with 0.5% Dy to create glass-ceramics in order to examine the local chemical environment of the rare earth ions (REI). More than 12 times enhancement of the emission at 2.9 and 3.5 μm was achieved in glass-ceramics produced using prolonged annealing time. Elemental mapping showed clear evidence that Ga{sub 2}S{sub 3} crystalline grains with a size of 50 nm were dispersed in a Ge-S glass matrix in the glass-ceramics, and the REI could only be found near the Ga{sub 2}S{sub 3} crystalline grains. From the unchanged lineshape of the emissions at 2.9 and 3.5 μm and lack of splitting of the absorption peaks, we concluded that the REI were bonded to Ga on the surface of the Ga{sub 2}S{sub 3} crystals.

  5. Magnetic and microwave absorption properties of rare earth ions (Sm3+, Er3+) doped strontium ferrite and its nanocomposites with polypyrrole

    NASA Astrophysics Data System (ADS)

    Luo, Juhua; Xu, Yang; Mao, Hongkai

    2015-05-01

    M-type strontium ferrite substituted by RE (RE=Sm3+, Er3+) were prepared via a sol-gel method. Polypyrrole (PPy)/ferrite nanocomposites (with 20 wt% ferrite) were prepared by in situ polymerization method in the presence of ammonium persulfate. Effect of the substituted RE ions on structure, magnetic properties and microwave absorption properties were investigated by X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and vector network analyzer. All XRD patterns show the single phase of strontium hexaferrite without other intermediate phases. The crystallite size of synthesized particle is within the range of 22.2-38.1 nm. The structural in character of the composites were investigated with FT-IR analysis. It shows that the ferrite successfully packed by PPy. TEM photographs show that the particle size had grown up to 50-100 nm after coating with PPy. In the magnetization for the PPy/SrSm0.3Fe11.7O19 (SrEr0.3Fe11.7O19) composites, the coercivity (Hc) of the composites both increased compared with the undoped composite while the saturation magnetization (Ms) appeared opposite change with different RE ions. Considering the electromagnetic loss and impedance matching comprehensively, the Er-doped ferrite/PPy composite got the better microwave absorption performance with the maximum RL value of -24.01 dB in 13.8 GHz at 3.0 mm. And its width (<-10 dB) has reached 7.2 GHz which has covered the whole Ku band.

  6. Incubational domain characterization in lightly doped ceria

    SciTech Connect

    Li Zhipeng; Mori, Toshiyuki; John Auchterlonie, Graeme; Zou Jin; Drennan, John

    2012-08-15

    Microstructures of both Gd- and Y-doped ceria with different doping level (i.e., 10 at% and 25 at%) have been comprehensively characterized by means of high resolution transmission electron microscopy and selected area electron diffraction. Coherent nano-sized domains can be widely observed in heavily doped ceria. Nevertheless, it was found that a large amount of dislocations actually exist in lightly doped ceria instead of heavily doped ones. Furthermore, incubational domains can be detected in lightly doped ceria, with dislocations located at the interfaces. The interactions between such linear dislocations and dopant defects have been simulated accordingly. As a consequence, the formation mechanism of incubational domains is rationalized in terms of the interaction between intrinsic dislocations of doped ceria and dopant defects. This study offers the insights into the initial state and related mechanism of the formation of nano-sized domains, which have been widely observed in heavily rare-earth-doped ceria in recent years. - Graphical abstract: Interactions between dislocations and dopants lead to incubational domain formation in lightly doped ceria. Highlights: Black-Right-Pointing-Pointer Microstructures were characterized in both heavily and light Gd-/Y-doped ceria. Black-Right-Pointing-Pointer Dislocations are existed in lightly doped ceria rather than heavily doped one. Black-Right-Pointing-Pointer Interactions between dislocations and dopant defects were simulated. Black-Right-Pointing-Pointer Formation of dislocation associated incubational domain is rationalized.

  7. Integrating Science Content and Pedagogy in the Earth, Life, and Physical Sciences: A K-8 Pre-Service Teacher Preparation Continuum at the University of Delaware

    NASA Astrophysics Data System (ADS)

    Madsen, J.; Allen, D.; Donham, R.; Fifield, S.; Ford, D.; Shipman, H.; Dagher, Z.

    2007-12-01

    University of Delaware faculty in the geological sciences, biological sciences, and the physics and astronomy departments have partnered with faculty and researchers from the school of education to form a continuum for K- 8 pre-service teacher preparation in science. The goal of the continuum is to develop integrated understandings of content and pedagogy so that these future teachers can effectively use inquiry-based approaches in teaching science in their classrooms. Throughout the continuum where earth science content appears an earth system science approach, with emphasis on inquiry-based activities, is employed. The continuum for K-8 pre-service teachers includes a gateway content course in the earth, life, or physical sciences taken during the freshman year followed by integrated science content and methods courses taken during the sophomore year. These integrated courses, called the Science Semester, were designed and implemented with funding from the National Science Foundation. During the Science Semester, traditional content and pedagogy subject matter boundaries are crossed to stress shared themes that teachers must understand to teach standards-based science. Students work collaboratively on multidisciplinary problem-based learning (PBL) activities that place science concepts in authentic contexts and build learning skills. They also critically explore the theory and practice of elementary science teaching, drawing on their shared experiences of inquiry learning during the Science Semester. The PBL activities that are the hallmark of the Science Semester provide the backdrop through which fundamental earth system interactions can be studied. For example in a PBL investigation that focuses on kids, cancer, and the environment, the hydrologic cycle with emphasis on surface runoff and ground water contamination is studied. Those students seeking secondary certification in science will enroll, as a bridge toward their student teaching experience, in an

  8. Origins of conductivity improvement in fluoride-enhanced silicon doping of ZnO films.

    PubMed

    Rashidi, Nazanin; Vai, Alex T; Kuznetsov, Vladimir L; Dilworth, Jonathan R; Edwards, Peter P

    2015-06-01

    Fluoride in spray pyrolysis precursor solutions for silicon-doped zinc oxide (SiZO) transparent conductor thin films significantly improves their electrical conductivity by enhancing silicon doping efficiency and not, as previously assumed, by fluoride doping. Containing only earth-abundant elements, SiZO thus prepared rivals the best solution-processed indium-doped ZnO in performance. PMID:25879727

  9. Origins of conductivity improvement in fluoride-enhanced silicon doping of ZnO films.

    PubMed

    Rashidi, Nazanin; Vai, Alex T; Kuznetsov, Vladimir L; Dilworth, Jonathan R; Edwards, Peter P

    2015-06-01

    Fluoride in spray pyrolysis precursor solutions for silicon-doped zinc oxide (SiZO) transparent conductor thin films significantly improves their electrical conductivity by enhancing silicon doping efficiency and not, as previously assumed, by fluoride doping. Containing only earth-abundant elements, SiZO thus prepared rivals the best solution-processed indium-doped ZnO in performance.

  10. Airplane dopes and doping

    NASA Technical Reports Server (NTRS)

    Smith, W H

    1919-01-01

    Cellulose acetate and cellulose nitrate are the important constituents of airplane dopes in use at the present time, but planes were treated with other materials in the experimental stages of flying. The above compounds belong to the class of colloids and are of value because they produce a shrinking action on the fabric when drying out of solution, rendering it drum tight. Other colloids possessing the same property have been proposed and tried. In the first stages of the development of dope, however, shrinkage was not considered. The fabric was treated merely to render it waterproof. The first airplanes constructed were covered with cotton fabric stretched as tightly as possible over the winds, fuselage, etc., and flying was possible only in fine weather. The necessity of an airplane which would fly under all weather conditions at once became apparent. Then followed experiments with rubberized fabrics, fabrics treated with glue rendered insoluble by formaldehyde or bichromate, fabrics treated with drying and nondrying oils, shellac, casein, etc. It was found that fabrics treated as above lost their tension in damp weather, and the oil from the motor penetrated the proofing material and weakened the fabric. For the most part the film of material lacked durability. Cellulose nitrate lacquers, however were found to be more satisfactory under varying weather conditions, added less weight to the planes, and were easily applied. On the other hand, they were highly inflammable, and oil from the motor penetrated the film of cellulose nitrate, causing the tension of the fabric to be relaxed.

  11. Mitochondrial potential (ΔΨm) changes in single rat hepatocytes: the effect of orthovanadate nanoparticles doped with rare-earth elements.

    PubMed

    Kavok, Nataliya S; Averchenko, Katherine A; Klochkov, Vladimir K; Yefimova, Svetlana L; Malyukin, Yuri V

    2014-12-01

    Rare-earth-based nanoparticles (NPs) are widely used as fluorescent probes for imaging in vitro and in vivo. One of the challenges that restrain NPs applications in biomedical research is their effect on subcellular structures. In this paper, the ability of lanthanide NPs to affect the cellular oxidative balance and alter the mitochondrial function was analyzed. Since size and shape mutually affect the cellular internalization and intracellular distribution of NPs, the investigations were performed with NPs of spherical (GdYVO4:Eu(3+), spindle-(GdVO4: Eu(3+) and rod-like (LaVO4: Eu(3+) shapes. Quantitative microfluorimetry with JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine iodide) as a mitochondrial probe was used for monitoring of the mitochondrial transmembrane potential (ΔΨ m) in single living cells. Changes in the ratio of the JC-1 probe fluorescence were used to analyze the NPs effect on ΔΨ(m). The fastest suppressive effect (within 1 hour) was found for spherical NPs. Gradual lowering of ΔΨ(m) was observed at the exposure of cells within 24 hours for all types of NPs. Exogenous thiols were required for ΔΨ(m) protection. The protective role of exogenous glutathione (GSH) proves that the increase of reactive oxygen species (ROS) formation with depletion of GSH can mediate NPs toxicity. The dynamics of the shape-dependent effect can be explained by the features of NPs transportation into cells.

  12. Multimodal bioimaging using rare earth doped Gd2O2S: Yb/Er phosphor with upconversion luminescence and magnetic resonance properties.

    PubMed

    Ajithkumar, G; Yoo, Benjamin; Goral, Dara E; Hornsby, Peter J; Lin, Ai-Ling; Ladiwala, Uma; Dravid, Vinayak P; Sardar, Dhiraj K

    2013-03-21

    While infrared upconversion imaging using halide nanoparticles are so common the search for a very efficient halide free upconverting phosphors is still lacking. In this article we report Gd2O2S:Yb/Er,YbHo,YbTm systems as a very efficient alternative phosphors that show upconversion efficiency comparable or even higher than existing halide phosphors. While the majority of rare earth dopants provide the necessary features for optical imaging, the paramagnetic Gd ion also contributes to the magnetic imaging,thereby resulting in a system with bimodal imaging features. Results from imaging of the nanoparticles together with aggregates of cultured cells have suggested that imaging of the particles in living animals may be possible. In vitro tests revealed no signficant toxicity because no cell death was observed when the nanoparticles were in the presence of growing cells in culture. Measurement of the magnetization of the phosphor shows that the particles are strongly magnetic, thus making them suitable as an MRI agent.

  13. Temperature-dependent structure of Tb-doped magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Rice, Katherine P.; Russek, Stephen E.; Geiss, Roy H.; Shaw, Justin M.; Usselman, Robert J.; Evarts, Eric R.; Silva, Thomas J.; Nembach, Hans T.; Arenholz, Elke; Idzerda, Yves U.

    2015-02-01

    High quality 5 nm cubic Tb-doped magnetite nanoparticles have been synthesized by a wet-chemical method to investigate tailoring of magnetic properties for imaging and biomedical applications. We show that the Tb is incorporated into the octahedral 3+ sites. High-angle annular dark-field microscopy shows that the dopant is well-distributed throughout the particle, and x-ray diffraction measurements show a small lattice parameter shift with the inclusion of a rare-earth dopant. Magnetization and x-ray magnetic circular dichroism data indicate that the Tb spins are unpolarized and weakly coupled to the iron spin lattice at room temperature, and begin to polarize and couple to the iron oxide lattice at temperatures below 50 K. Broadband ferromagnetic resonance measurements show no increase in magnetic damping at room temperature for Tb-doped nanoparticles relative to undoped nanoparticles, further confirming weak coupling between Fe and Tb spins at room temperature. The Gilbert damping constant, α, is remarkably low for the Tb-doped nanoparticles, with α = 0.024 ± 0.003. These nanoparticles, which have a large fixed moment, a large fluctuating moment and optically active rare-earth elements, are potential high-relaxivity T1 and T2 MRI agents with integrated optical signatures.

  14. Temperature-dependent structure of Tb-doped magnetite nanoparticles

    SciTech Connect

    Rice, Katherine P.; Russek, Stephen E. Shaw, Justin M.; Usselman, Robert J.; Evarts, Eric R.; Silva, Thomas J.; Nembach, Hans T.; Geiss, Roy H.; Arenholz, Elke; Idzerda, Yves U.

    2015-02-09

    High quality 5 nm cubic Tb-doped magnetite nanoparticles have been synthesized by a wet-chemical method to investigate tailoring of magnetic properties for imaging and biomedical applications. We show that the Tb is incorporated into the octahedral 3+ sites. High-angle annular dark-field microscopy shows that the dopant is well-distributed throughout the particle, and x-ray diffraction measurements show a small lattice parameter shift with the inclusion of a rare-earth dopant. Magnetization and x-ray magnetic circular dichroism data indicate that the Tb spins are unpolarized and weakly coupled to the iron spin lattice at room temperature, and begin to polarize and couple to the iron oxide lattice at temperatures below 50 K. Broadband ferromagnetic resonance measurements show no increase in magnetic damping at room temperature for Tb-doped nanoparticles relative to undoped nanoparticles, further confirming weak coupling between Fe and Tb spins at room temperature. The Gilbert damping constant, α, is remarkably low for the Tb-doped nanoparticles, with α = 0.024 ± 0.003. These nanoparticles, which have a large fixed moment, a large fluctuating moment and optically active rare-earth elements, are potential high-relaxivity T1 and T2 MRI agents with integrated optical signatures.

  15. Application of an integrated biomarker response index to assess ground water contamination in the vicinity of a rare earth mine tailings site.

    PubMed

    Si, Wantong; He, Xiaoying; Li, Ailing; Liu, Li; Li, Jisheng; Gong, Donghui; Liu, Juan; Liu, Jumei; Shen, Weishou; Zhang, Xuefeng

    2016-09-01

    We utilized a multi-biomarker approach (Integrated Biomarker Response version 2, IBRv2) to investigate the scope and dispersion of groundwater contamination surrounding a rare earth mine tailings impoundment. Parameters of SD rat included in our IBRv2 analyses were glutathione levels, superoxide dismutase, catalase, and glutathione peroxidase activities, total anti-oxidative capacity, chromosome aberration, and micronucleus formation. The concentration of 20 pollutants including Cl(-), SO4 (2-), Na(+), K(+), Mg(2+), Ca(2+), TH, CODMn, As, Se, TDS, Be, Mn, Co, Ni, Cu, Zn, Mo, Cd, and Pb in the groundwater were also analyzed. The results of this study indicated that groundwater polluted by tailings impoundment leakage exhibited significant ecotoxicological effects. The selected biomarkers responded sensitively to groundwater pollution. Analyses showed a significant relationship between IBRv2 values and the Nemerow composite index. IBRv2 could serve as a sensitive ecotoxicological diagnosis method for assessing groundwater contamination in the vicinity of rare earth mine tailings. According to the trend of IBRv2 value and Nemerow composite index, the maximum diffusion distance of groundwater pollutants from rare earth mine tailings was approximately 5.7 km. PMID:27230138

  16. Application of an integrated biomarker response index to assess ground water contamination in the vicinity of a rare earth mine tailings site.

    PubMed

    Si, Wantong; He, Xiaoying; Li, Ailing; Liu, Li; Li, Jisheng; Gong, Donghui; Liu, Juan; Liu, Jumei; Shen, Weishou; Zhang, Xuefeng

    2016-09-01

    We utilized a multi-biomarker approach (Integrated Biomarker Response version 2, IBRv2) to investigate the scope and dispersion of groundwater contamination surrounding a rare earth mine tailings impoundment. Parameters of SD rat included in our IBRv2 analyses were glutathione levels, superoxide dismutase, catalase, and glutathione peroxidase activities, total anti-oxidative capacity, chromosome aberration, and micronucleus formation. The concentration of 20 pollutants including Cl(-), SO4 (2-), Na(+), K(+), Mg(2+), Ca(2+), TH, CODMn, As, Se, TDS, Be, Mn, Co, Ni, Cu, Zn, Mo, Cd, and Pb in the groundwater were also analyzed. The results of this study indicated that groundwater polluted by tailings impoundment leakage exhibited significant ecotoxicological effects. The selected biomarkers responded sensitively to groundwater pollution. Analyses showed a significant relationship between IBRv2 values and the Nemerow composite index. IBRv2 could serve as a sensitive ecotoxicological diagnosis method for assessing groundwater contamination in the vicinity of rare earth mine tailings. According to the trend of IBRv2 value and Nemerow composite index, the maximum diffusion distance of groundwater pollutants from rare earth mine tailings was approximately 5.7 km.

  17. EarthScope's Plate Boundary Observatory in Alaska: Building on Existing Infrastructure to Provide a Platform for Integrated Research and Hazard-monitoring Efforts

    NASA Astrophysics Data System (ADS)

    Boyce, E. S.; Bierma, R. M.; Willoughby, H.; Feaux, K.; Mattioli, G. S.; Enders, M.; Busby, R. W.

    2014-12-01

    EarthScope's geodetic component in Alaska, the UNAVCO-operated Plate Boundary Observatory (PBO) network, includes 139 continuous GPS sites and 41 supporting telemetry relays. These are spread across a vast area, from northern AK to the Aleutians. Forty-five of these stations were installed or have been upgraded in cooperation with various partner agencies and currently provide data collection and transmission for more than one group. Leveraging existing infrastructure normally has multiple benefits, such as easier permitting requirements and costs savings through reduced overall construction and maintenance expenses. At some sites, PBO-AK power and communications systems have additional capacity beyond that which is needed for reliable acquisition of GPS data. Where permits allow, such stations could serve as platforms for additional instrumentation or real-time observing needs. With the expansion of the Transportable Array (TA) into Alaska, there is increased interest to leverage existing EarthScope resources for station co-location and telemetry integration. Because of the complexity and difficulty of long-term O&M at PBO sites, however, actual integration of GPS and seismic equipment must be considered on a case-by-case basis. UNAVCO currently operates two integrated GPS/seismic stations in collaboration with the Alaska Earthquake Center, and three with the Alaska Volcano Observatory. By the end of 2014, PBO and TA plan to install another four integrated and/or co-located geodetic and seismic systems. While three of these are designed around existing PBO stations, one will be a completely new TA installation, providing PBO with an opportunity to expand geodetic data collection in Alaska within the limited operations and maintenance phase of the project. We will present some of the design considerations, outcomes, and lessons learned from past and ongoing projects to integrate seismometers and other instrumentation at PBO-Alaska stations. Developing the PBO

  18. Single-frequency Er(3+)-doped silica-based planar waveguide laser with integrated photo-imprinted Bragg reflectors

    NASA Astrophysics Data System (ADS)

    Kitagawa, T.; Bilodeau, F.; Malo, B.; Theriault, S.; Albert, J.; Jihnson, D. C.; Hill, K. O.; Hattori, K.; Hibino, Y.

    1994-08-01

    Single-longitudinal-mode operation of Er(3+)-P2O5 -codoped silica planar waveguide lasers which are equipped with integrated Bragg grating reflectors is demonstrated, with a polarized output of 340 mu W at 1546 nm. The gratings are photo-imprinted using 193 nm light exposure through a phase mask in GeO2-free optical waveguides that have been sensitized by H2 loading.

  19. Three-dimensional cavity quantum electrodynamics with a rare-earth spin ensemble

    NASA Astrophysics Data System (ADS)

    Probst, S.; Tkalčec, A.; Rotzinger, H.; Rieger, D.; Le Floch, J.-M.; Goryachev, M.; Tobar, M. E.; Ustinov, A. V.; Bushev, P. A.

    2014-09-01

    We present cavity QED experiments with an Er3+:Y2SiO5 crystal magnetically coupled to a three-dimensional (3D) cylindrical sapphire loaded copper resonator. Such waveguide cavities are promising for the realization of a superconducting quantum processor. Here, we demonstrate the coherent integration of a rare-earth spin ensemble with the 3D architecture. The collective coupling strength of the Er3+ spins to the 3D cavity is 21 MHz. The cylindrical sapphire loaded resonator allowed us to explore the anisotropic collective coupling between the rare-earth doped crystal and the cavity. This work shows the potential of spin doped solids in 3D quantum circuits for application as microwave quantum memories as well as for prospective microwave to optical interfaces.

  20. Investigation of InP/InGaAs metamorphic co-integrated complementary doping-channel field-effect transistors for logic application

    NASA Astrophysics Data System (ADS)

    Tsai, Jung-Hui

    2014-01-01

    DC performance of InP/InGaAs metamorphic co-integrated complementary doping-channel field-effect transistors (DCFETs) grown on a low-cost GaAs substrate is first demonstrated. In the complementary DCFETs, the n-channel device was fabricated on the InxGa1-xP metamorphic linearly graded buffer layer and the p-channel field-effect transistor was stacked on the top of the n-channel device. Particularly, the saturation voltage of the n-channel device is substantially reduced to decrease the VOL and VIH values attributed that two-dimensional electron gas is formed and could be modulated in the n-InGaAs channel. Experimentally, a maximum extrinsic transconductance of 215 (17) mS/mm and a maximum saturation current density of 43 (-27) mA/mm are obtained in the n-channel (p-channel) device. Furthermore, the noise margins NMH and NML are up to 0.842 and 0.330 V at a supply voltage of 1.5 V in the complementary logic inverter application.

  1. The need and potential for building a integrated knowledge-base of the Earth-Human system

    NASA Astrophysics Data System (ADS)

    Jacobs, Clifford

    2011-03-01

    The pursuit of scientific understanding is increasingly based on interdisciplinary research. To understand more deeply the planet and its interactions requires a progressively more holistic approach, exploring knowledge coming from all scientific and engineering disciplines including but not limited to, biology, chemistry, computer sciences, geosciences, material sciences, mathematics, physics, cyberinfrastucture, and social sciences. Nowhere is such an approach more critical than in the study of global climate change in which one of the major challenges is the development of next-generation Earth System Models that include coupled and interactive representations of ecosystems, agricultural working lands and forests, urban environments, biogeochemistry, atmospheric chemistry, ocean and atmospheric currents, the water cycle, land ice, and human activities.

  2. Ray-tracing studies and path-integrated gains of ELF unducted whistler mode waves in the earth's magnetosphere

    NASA Technical Reports Server (NTRS)

    Huang, C. Y.; Goertz, C. K.

    1983-01-01

    Gyroresonance and Landau resonance interactions between unducted low-frequency whistler waves and trapped electrons in the earth's plasmasphere have been studied. Ray paths for waves launched near the plasmapause have been traced. In agreement with recent findings by Thorne et al. (1979), waves have been found which return through the equatorial zone with field-aligned wave normal angles. However, when the growth along the ray path is calculated for such waves, assuming an electron distribution function of the form E exp -n sin exp m alpha, it is found that for all the waves considered, the local growth rate becomes negative before plasmapause reflection, limiting the total gain to small values. Most waves reach zero gain before reflection. This is the result of Landau damping at oblique propagation angles, which necessarily occurs before reflection can take place. It is concluded that the concept of cyclic ray paths does not provide an explanation for the generation of unguided plasmaspheric hiss.

  3. The fractionation and geochemical characteristics of rare earth elements measured in ambient size-resolved PM in an integrated iron and steelmaking industry zone.

    PubMed

    Dai, Qili; Li, Liwei; Yang, Jiamei; Liu, Baoshuang; Bi, Xiaohui; Wu, Jianhui; Zhang, YuFen; Yao, Lin; Feng, Yinchang

    2016-09-01

    Improved understanding of the fractionation and geochemical characteristic of rare earth elements (REEs) from steel plant emissions is important due to the unclear atmospheric signature of these elements and their adverse impact on human health and the environment. In this study, ambient particulate matter of different sizes was collected from one site in an integrated iron and steelmaking industrial zone (HG) and one urban background site with no direct industrial emissions (ZWY) during a 1-year sampling campaign in China. The total concentrations of REEs for TSP, PM10, and PM2.5 were 27.248, 14.989, 3.542 ng/m(3) in HG and 6.326, 5.274, 1.731 ng/m(3), respectively, in ZWY, which revealed the local influence of the steelmaking activities to the air quality. With respect to ZWY, the REEs in HG site are obviously fractionated in the coarser fraction, and LREEs account for more than 80 % of the total REE burden in all of the samples. Additionally, the REEs in HG and ZWY show a homogeneous trend with successively increased LREE/HREE ratios from the coarse particles to the fine particles. In our samples, La, Ce, Nd, and Sm are the most enriched rare earth elements, especially in the HG site. Moreover, ternary diagrams of LaCeSm indicate that the REEs in HG are potentially contributed by steelworks, carrier vehicles, coal combustion, and road dust re-suspension.

  4. Expedition Earth and Beyond: Engaging Classrooms in Student-Led Research Using NASA Data, Access to Scientists, and Integrated Educational Strategies

    NASA Technical Reports Server (NTRS)

    Graff, P. V.; Stefanov, W. L.; Willis, K. J.; Runco, S.; McCollum, T.; Baker, M.; Lindgren, C.; Mailhot, M.

    2011-01-01

    Classroom teachers are challenged with engaging and preparing today s students for the future. Activities are driven by state required skills, education standards, and high-stakes testing. Providing educators with standards-aligned, inquiry-based activities that will help them engage their students in student-led research in the classroom will help them teach required standards, essential skills, and help inspire their students to become motivated learners. The Astromaterials Research and Exploration Science (ARES) Education Program, classroom educators, and ARES scientists at the NASA Johnson Space Center created the Expedition Earth and Beyond education program to help teachers promote student-led research in their classrooms (grades 5-14) by using NASA data, providing access to scientists, and using integrated educational strategies.

  5. Development of response models for the Earth Radiation Budget Experiment (ERBE) sensors. Part 2: Analysis of the ERBE integrating sphere ground calibration

    NASA Technical Reports Server (NTRS)

    Halyo, Nesim; Taylor, Deborah B.

    1987-01-01

    An explicit solution of the spectral radiance leaving an arbitrary point on the wall of a spherical cavity with diffuse reflectivity is obtained. The solution is applicable to spheres with an arbitrary number of openings of any size and shape, an arbitrary number of light sources with possible non-diffuse characteristics, a non-uniform sphere wall temperature distribution, non-uniform and non-diffuse sphere wall emissivity and non-uniform but diffuse sphere wall spectral reflectivity. A general measurement equation describing the output of a sensor with a given field of view, angular and spectral response measuring the sphere output is obtained. The results are applied to the Earth Radiation Budget Experiment (ERBE) integrating sphere. The sphere wall radiance uniformity, loading effects and non-uniform wall temperature effects are investigated. It is shown that using appropriate interpretation and processing, a high-accuracy short-wave calibration of the ERBE sensors can be achieved.

  6. Peru Water Resources: Integrating NASA Earth Observations into Water Resource Planning and Management in Perus La Libertad Region

    NASA Technical Reports Server (NTRS)

    Padgett-Vasquez, Steve; Steentofte, Catherine; Holbrook, Abigail

    2014-01-01

    Developing countries often struggle with providing water security and sanitation services to their populations. An important aspect of improving security and sanitation is developing a comprehensive understanding of the country's water budget. Water For People, a non-profit organization dedicated to providing clean drinking water, is working with the Peruvian government to develop a water budget for the La Libertad region of Peru which includes the creation of an extensive watershed management plan. Currently, the data archive of the necessary variables to create the water management plan is extremely limited. Implementing NASA Earth observations has bolstered the dataset being used by Water For People, and the METRIC (Mapping EvapoTranspiration at High Resolution and Internalized Calibration) model has allowed for the estimation of the evapotranspiration values for the region. Landsat 8 imagery and the DEM (Digital Elevation Model) from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor onboard Terra were used to derive the land cover information, and were used in conjunction with local weather data of Cascas from Peru's National Meteorological and Hydrological Service (SENAMHI). Python was used to combine input variables and METRIC model calculations to approximate the evapotranspiration values for the Ochape sub-basin of the Chicama River watershed. Once calculated, the evapotranspiration values and methodology were shared Water For People to help supplement their decision support tools in the La Libertad region of Peru and potentially apply the methodology in other areas of need.

  7. An integrated modeling system for estimating glacier and snow melt driven streamflow from remote sensing and earth system data products in the Himalayas

    NASA Astrophysics Data System (ADS)

    Brown, M. E.; Racoviteanu, A. E.; Tarboton, D. G.; Gupta, A. Sen; Nigro, J.; Policelli, F.; Habib, S.; Tokay, M.; Shrestha, M. S.; Bajracharya, S.; Hummel, P.; Gray, M.; Duda, P.; Zaitchik, B.; Mahat, V.; Artan, G.; Tokar, S.

    2014-11-01

    Quantification of the contribution of the hydrologic components (snow, ice and rain) to river discharge in the Hindu Kush Himalayan (HKH) region is important for decision-making in water sensitive sectors, and for water resources management and flood risk reduction. In this area, access to and monitoring of the glaciers and their melt outflow is challenging due to difficult access, thus modeling based on remote sensing offers the potential for providing information to improve water resources management and decision making. This paper describes an integrated modeling system developed using downscaled NASA satellite based and earth system data products coupled with in-situ hydrologic data to assess the contribution of snow and glaciers to the flows of the rivers in the HKH region. Snow and glacier melt was estimated using the Utah Energy Balance (UEB) model, further enhanced to accommodate glacier ice melt over clean and debris-covered tongues, then meltwater was input into the USGS Geospatial Stream Flow Model (GeoSFM). The two model components were integrated into Better Assessment Science Integrating point and Nonpoint Sources modeling framework (BASINS) as a user-friendly open source system and was made available to countries in high Asia. Here we present a case study from the Langtang Khola watershed in the monsoon-influenced Nepal Himalaya, used to validate our energy balance approach and to test the applicability of our modeling system. The snow and glacier melt model predicts that for the eight years used for model evaluation (October 2003-September 2010), the total surface water input over the basin was 9.43 m, originating as 62% from glacier melt, 30% from snowmelt and 8% from rainfall. Measured streamflow for those years were 5.02 m, reflecting a runoff coefficient of 0.53. GeoSFM simulated streamflow was 5.31 m indicating reasonable correspondence between measured and model confirming the capability of the integrated system to provide a quantification of

  8. An Integrated Modeling System for Estimating Glacier and Snow Melt Driven Streamflow from Remote Sensing and Earth System Data Products in the Himalayas

    NASA Technical Reports Server (NTRS)

    Brown, M. E.; Racoviteanu, A. E.; Tarboton, D. G.; Sen Gupta, A.; Nigro, J.; Policelli, F.; Habib, S.; Tokay, M.; Shrestha, M. S.; Bajracharya, S.

    2014-01-01

    Quantification of the contribution of the hydrologic components (snow, ice and rain) to river discharge in the Hindu Kush Himalayan (HKH) region is important for decision-making in water sensitive sectors, and for water resources management and flood risk reduction. In this area, access to and monitoring of the glaciers and their melt outflow is challenging due to difficult access, thus modeling based on remote sensing offers the potential for providing information to improve water resources management and decision making. This paper describes an integrated modeling system developed using downscaled NASA satellite based and earth system data products coupled with in-situ hydrologic data to assess the contribution of snow and glaciers to the flows of the rivers in the HKH region. Snow and glacier melt was estimated using the Utah Energy Balance (UEB) model, further enhanced to accommodate glacier ice melt over clean and debris-covered tongues, then meltwater was input into the USGS Geospatial Stream Flow Model (Geo- SFM). The two model components were integrated into Better Assessment Science Integrating point and Nonpoint Sources modeling framework (BASINS) as a user-friendly open source system and was made available to countries in high Asia. Here we present a case study from the Langtang Khola watershed in the monsoon-influenced Nepal Himalaya, used to validate our energy balance approach and to test the applicability of our modeling system. The snow and glacier melt model predicts that for the eight years used for model evaluation (October 2003-September 2010), the total surface water input over the basin was 9.43 m, originating as 62% from glacier melt, 30% from snowmelt and 8% from rainfall. Measured streamflow for those years were 5.02 m, reflecting a runoff coefficient of 0.53. GeoSFM simulated streamflow was 5.31 m indicating reasonable correspondence between measured and model confirming the capability of the integrated system to provide a quantification

  9. Path integral Monte Carlo simulations of H2 adsorbed to lithium-doped benzene: A model for hydrogen storage materials

    NASA Astrophysics Data System (ADS)

    Lindoy, Lachlan P.; Kolmann, Stephen J.; D'Arcy, Jordan H.; Crittenden, Deborah L.; Jordan, Meredith J. T.

    2015-11-01

    Finite temperature quantum and anharmonic effects are studied in H2-Li+-benzene, a model hydrogen storage material, using path integral Monte Carlo (PIMC) simulations on an interpolated potential energy surface refined over the eight intermolecular degrees of freedom based upon M05-2X/6-311+G(2df,p) density functional theory calculations. Rigid-body PIMC simulations are performed at temperatures ranging from 77 K to 150 K, producing both quantum and classical probability density histograms describing the adsorbed H2. Quantum effects broaden the histograms with respect to their classical analogues and increase the expectation values of the radial and angular polar coordinates describing the location of the center-of-mass of the H2 molecule. The rigid-body PIMC simulations also provide estimates of the change in internal energy, ΔUads, and enthalpy, ΔHads, for H2 adsorption onto Li+-benzene, as a function of temperature. These estimates indicate that quantum effects are important even at room temperature and classical results should be interpreted with caution. Our results also show that anharmonicity is more important in the calculation of U and H than coupling—coupling between the intermolecular degrees of freedom becomes less important as temperature increases whereas anharmonicity becomes more important. The most anharmonic motions in H2-Li+-benzene are the "helicopter" and "ferris wheel" H2 rotations. Treating these motions as one-dimensional free and hindered rotors, respectively, provides simple corrections to standard harmonic oscillator, rigid rotor thermochemical expressions for internal energy and enthalpy that encapsulate the majority of the anharmonicity. At 150 K, our best rigid-body PIMC estimates for ΔUads and ΔHads are -13.3 ± 0.1 and -14.5 ± 0.1 kJ mol-1, respectively.

  10. Path integral Monte Carlo simulations of H2 adsorbed to lithium-doped benzene: A model for hydrogen storage materials.

    PubMed

    Lindoy, Lachlan P; Kolmann, Stephen J; D'Arcy, Jordan H; Crittenden, Deborah L; Jordan, Meredith J T

    2015-11-21

    Finite temperature quantum and anharmonic effects are studied in H2-Li(+)-benzene, a model hydrogen storage material, using path integral Monte Carlo (PIMC) simulations on an interpolated potential energy surface refined over the eight intermolecular degrees of freedom based upon M05-2X/6-311+G(2df,p) density functional theory calculations. Rigid-body PIMC simulations are performed at temperatures ranging from 77 K to 150 K, producing both quantum and classical probability density histograms describing the adsorbed H2. Quantum effects broaden the histograms with respect to their classical analogues and increase the expectation values of the radial and angular polar coordinates describing the location of the center-of-mass of the H2 molecule. The rigid-body PIMC simulations also provide estimates of the change in internal energy, ΔUads, and enthalpy, ΔHads, for H2 adsorption onto Li(+)-benzene, as a function of temperature. These estimates indicate that quantum effects are important even at room temperature and classical results should be interpreted with caution. Our results also show that anharmonicity is more important in the calculation of U and H than coupling-coupling between the intermolecular degrees of freedom becomes less important as temperature increases whereas anharmonicity becomes more important. The most anharmonic motions in H2-Li(+)-benzene are the "helicopter" and "ferris wheel" H2 rotations. Treating these motions as one-dimensional free and hindered rotors, respectively, provides simple corrections to standard harmonic oscillator, rigid rotor thermochemical expressions for internal energy and enthalpy that encapsulate the majority of the anharmonicity. At 150 K, our best rigid-body PIMC estimates for ΔUads and ΔHads are -13.3 ± 0.1 and -14.5 ± 0.1 kJ mol(-1), respectively.

  11. Path integral Monte Carlo simulations of H2 adsorbed to lithium-doped benzene: A model for hydrogen storage materials.

    PubMed

    Lindoy, Lachlan P; Kolmann, Stephen J; D'Arcy, Jordan H; Crittenden, Deborah L; Jordan, Meredith J T

    2015-11-21

    Finite temperature quantum and anharmonic effects are studied in H2-Li(+)-benzene, a model hydrogen storage material, using path integral Monte Carlo (PIMC) simulations on an interpolated potential energy surface refined over the eight intermolecular degrees of freedom based upon M05-2X/6-311+G(2df,p) density functional theory calculations. Rigid-body PIMC simulations are performed at temperatures ranging from 77 K to 150 K, producing both quantum and classical probability density histograms describing the adsorbed H2. Quantum effects broaden the histograms with respect to their classical analogues and increase the expectation values of the radial and angular polar coordinates describing the location of the center-of-mass of the H2 molecule. The rigid-body PIMC simulations also provide estimates of the change in internal energy, ΔUads, and enthalpy, ΔHads, for H2 adsorption onto Li(+)-benzene, as a function of temperature. These estimates indicate that quantum effects are important even at room temperature and classical results should be interpreted with caution. Our results also show that anharmonicity is more important in the calculation of U and H than coupling-coupling between the intermolecular degrees of freedom becomes less important as temperature increases whereas anharmonicity becomes more important. The most anharmonic motions in H2-Li(+)-benzene are the "helicopter" and "ferris wheel" H2 rotations. Treating these motions as one-dimensional free and hindered rotors, respectively, provides simple corrections to standard harmonic oscillator, rigid rotor thermochemical expressions for internal energy and enthalpy that encapsulate the majority of the anharmonicity. At 150 K, our best rigid-body PIMC estimates for ΔUads and ΔHads are -13.3 ± 0.1 and -14.5 ± 0.1 kJ mol(-1), respectively. PMID:26590532

  12. From land use to land cover: Restoring the afforestation signal in a coupled integrated assessment - earth system model and the implications for CMIP5 RCP simulations

    SciTech Connect

    Di Vittorio, Alan V.; Chini, Louise M.; Bond-Lamberty, Benjamin; Mao, Jiafu; Shi, Xiaoying; Truesdale, John E.; Craig, Anthony P.; Calvin, Katherine V.; Jones, Andrew D.; Collins, William D.; Edmonds, James A.; Hurtt, George; Thornton, Peter E.; Thomson, Allison M.

    2014-11-27

    Climate projections depend on scenarios of fossil fuel emissions and land use change, and the IPCC AR5 parallel process assumes consistent climate scenarios across Integrated Assessment and Earth System Models (IAMs and ESMs). To facilitate consistency, CMIP5 used a novel land use harmonization to provide ESMs with seamless, 1500-2100 land use trajectories generated by historical data and four IAMs. However, we have identified and partially addressed a major gap in the CMIP5 land coupling design. The CMIP5 Community ESM (CESM) global afforestation is only 22% of RCP4.5 afforestation from 2005 to 2100. Likewise, only 17% of the Global Change Assessment Model’s (GCAM’s) 2040 RCP4.5 afforestation signal, and none of the pasture loss, were transmitted to CESM within a newly integrated model. This is a critical problem because afforestation is necessary for achieving the RCP4.5 climate stabilization. We attempted to rectify this problem by modifying only the ESM component of the integrated model, enabling CESM to simulate 66% of GCAM’s afforestation in 2040, and 94% of GCAM’s pasture loss as grassland and shrubland losses. This additional afforestation increases vegetation carbon gain by 19 PgC and decreases atmospheric CO2 gain by 8 ppmv from 2005 to 2040, implying different climate scenarios between CMIP5 GCAM and CESM. Similar inconsistencies likely exist in other CMIP5 model results, primarily because land cover information is not shared between models, with possible contributions from afforestation exceeding model-specific, potentially viable forest area. Further work to harmonize land cover among models will be required to adequately rectify this problem.

  13. The Quickest, Lowest-cost Lunar Resource Assessment Program: Integrated High-tech Earth-based Astronomy

    NASA Technical Reports Server (NTRS)

    Pieters, Carle M.

    1992-01-01

    Science and technology applications for the Moon have not fully kept pace with technical advancements in sensor development and analytical information extraction capabilities. Appropriate unanswered questions for the Moon abound, but until recently there has been little motivation to link sophisticated technical capabilities with specific measurement and analysis projects. Over the last decade enormous technical progress has been made in the development of (1) CCD photometric array detectors; (2) visible to near-infrared imaging spectrometers; (3)infrared spectroscopy; (4) high-resolution dual-polarization radar imaging at 3.5, 12, and 70 cm; and equally important (5) data analysis and information extraction techniques using compact powerful computers. Parts of each of these have been tested separately, but there has been no programmatic effort to develop and optimize instruments to meet lunar science and resource assessment needs (e.g., specific wavelength range, resolution, etc.) nor to coordinate activities so that the symbiotic relation between different kinds of data can be fully realized. No single type of remotely acquired data completely characterizes the lunar environment, but there has been little opportunity for integration of diverse advanced sensor data for the Moon. Two examples of technology concepts for lunar measurements are given. Using VIS/near-IR spectroscopy, the mineral composition of surface material can be derived from visible and near-infrared radiation reflected from the surface. The surface and subsurface scattering properties of the Moon can be analyzed using radar backscattering imaging.

  14. Integration of Multiple OGC Standards for Delivery of Earth Science Information - Presentation of Time-Enabled WMS Through KML as Implemented by the PHAiRS Project

    NASA Astrophysics Data System (ADS)

    Hudspeth, W. B.; Benedict, K. K.

    2008-12-01

    Since 2004 the Earth Data Analysis Center has, in collaboration with researchers from the University of Arizona and George Mason University, with funding from NASA, developed a services oriented architecture (SOA) designed for the delivery of historic and current dust forecast data products to the public health user community. This system has generated nearly three years of daily 48-hour dust forecasts, ultimately representing over 289,000 individual hourly forecast rasters for ground surface dust concentrations in four model particle size classes and PM 2.5 and PM 10 size classes. This large collection of model outputs is published as a time-enabled Open Geospatial Consortium (OGC) Web Map Service (WMS) that allows for the efficient retrieval of a single hourly forecast map image for each of these particle size classes, for the entire collection of model outputs. While this WMS service has proven effective in meeting the specific project goals of providing services that support the integration of project products into existing public health decision support systems, the development of an alternative visualization capability that takes advantage of virtual globe technologies was also seen as a valuable complementary capability for making these model outputs accessible to a greater audience of environmental public health users. This paper presents the results of a development effort that produced a system that automatically generates time-enabled KML that enables sequential acquisition of hourly model outputs (via time-enabled WMS) in time-enabled virtual globe applications (e.g. Google Earth). While this effort has proven very successful, it has also highlighted areas where support for time-enabled WMS could be improved, both within the KML standard, and within clients that implement time-enabled viewers.

  15. Measuring Vertical Motions of the Earth's Surface on Long Time Scales through Integration of Surface Uplift Proxies with Climate Modeling

    NASA Astrophysics Data System (ADS)

    Garzione, C. N.; Poulsen, C. J.; McQuarrie, N.; Ehlers, T. A.

    2012-12-01

    Paleoaltimetry techniques are increasingly applied to mountain belts to resolve spatial and temporal changes in elevation that constrain the geodynamic mechanisms that raise these regions. However, recent general circulation modeling (GCM) experiments have demonstrated that elevation change can impart a strong influence on atmospheric processes at critical thresholds that should affect stable isotope proxies for meteoric water composition and surface temperature. We view the integration of: 1) geologic evidence of the distribution of shortening and exhumation, 2) spatially extensive climate proxy data, and 3) carefully designed GCM modeling experiments as a path forward in resolving the significance of climate proxy data in determining paleoelevation. Here we provide an example of this approach for the Andes, where recently acquired paleoclimate records, as well as records of shortening and exhumation, provide increasing resolution of patterns of regional tectonics and climate change. The ultimate goal of our approach is to evaluate end-member scenarios of elevation change that include gradual surface uplift associated with gradual shortening of the crust and associated ablative subduction of the lower lithosphere versus punctuated, diachrochronous surface uplift associated with the removal of lower lithosphere and/or lower crustal flow. We take a two-pronged approach. First, we use estimates of the magnitude of shortening to postulate a gradual surface uplift history. Given the gradual surface uplift history, we use previous GCM experiments that track the climate change associated with elevation gain to evaluate whether proxy records of surface temperature and the δ18O of meteoric water conform to model predictions for gradual surface uplift, or whether additional surface uplift is required to account for certain climate change events. Second, we carry out a new set of GCM experiments to evaluate the climate effects of pulsed, diachronous surface uplift. We

  16. Assessing environmental drivers of vegetation greenness by integrating multiple earth observation data in the LPJmL dynamic global vegetation model

    NASA Astrophysics Data System (ADS)

    Forkel, Matthias; Carvalhais, Nuno; Schaphoff, Sibyll; von Bloh, Werner; Thurner, Martin; Thonicke, Kirsten

    2014-05-01

    Recently produced satellite datasets of vegetation greenness demonstrate a widespread greening of the earth in the last three decades. These positive trends in vegetation greenness are related to changes in leaf area, vegetation cover and photosynthetic activity. Climatic changes, CO2 fertilization, disturbances and other land cover changes are potential drivers of these greening trends. Nevertheless, different satellite datasets show different magnitudes and trends in vegetation greenness. This fact raises the question about the reliability of these datasets. On the other hand, global vegetation models can be potentially used to assess the effects of environmental drivers on vegetation greenness and thus to explore the environmental reliability of these datasets. Unfortunately, current vegetation models have several weaknesses in reproducing observed temporal dynamics in vegetation greenness. Our aim is to integrate multiple earth observation data sets in a dynamic global vegetation model in order to 1) improve the model's capability to reproduce observed dynamics and spatial patterns of vegetation greenness and 2) to assess the spatial and temporal importance of environmental drivers for the seasonal to decadal variability of vegetation greenness. For this purpose, we developed a data integration system for the LPJmL dynamic global vegetation model (LPJmL-DIS). We implemented a new phenology scheme in LPJmL to better represent observed temporal dynamics of FAPAR (fraction of absorbed photosynthetic active radiation). Model parameters were globally optimized using a genetic optimization algorithm. The model optimization was performed globally against 30 year FAPAR time series (GIMMS3g dataset), against 10 year albedo time series (MODIS) and global patterns of gross primary production as up-scaled from FLUXNET eddy covariance measurements. Additionally, we directly prescribed satellite observations of land and tree cover in LPJmL to better represent global

  17. Gene doping.

    PubMed

    Harridge, Stephen D R; Velloso, Cristiana P

    2008-01-01

    Gene doping is the misuse of gene therapy to enhance athletic performance. It has recently been recognised as a potential threat and subsequently been prohibited by the World Anti-Doping Agency. Despite concerns with safety and efficacy of gene therapy, the technology is progressing steadily. Many of the genes/proteins which are involved in determining key components of athletic performance have been identified. Naturally occurring mutations in humans as well as gene-transfer experiments in adult animals have shown that altered expression of these genes does indeed affect physical performance. For athletes, however, the gains in performance must be weighed against the health risks associated with the gene-transfer process, whereas the detection of such practices will provide new challenges for the anti-doping authorities.

  18. Earth Resources

    ERIC Educational Resources Information Center

    Brewer, Tom

    1970-01-01

    Reviews some of the more concerted, large-scale efforts in the earth resources areas" in order to help the computer community obtain insights into the activities it can jointly particpate in withthe earth resources community." (Author)

  19. Skylab explores the Earth

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Data from visual observations are integrated with results of analyses of approxmately 600 of the nearly 2000 photographs taken of Earth during the 84-day Skylab 4 mission to provide additional information on (1) Earth features and processes; (2) operational procedures and constraints in observing and photographing the planet; and (3) the use of man in real-time analysis of oceanic and atmospheric phenomena.

  20. Integrating Ideas for International Data Collaborations Through The Committee on Earth Observation Satellites (CEOS) International Directory Network (IDN)

    NASA Technical Reports Server (NTRS)

    Olsen, Lola M.

    2006-01-01

    The capabilities of the International Directory Network's (IDN) version MD9.5, along with a new version of the metadata authoring tool, "docBUILDER", will be presented during the Technology and Services Subgroup session of the Working Group on Information Systems and Services (WGISS). Feedback provided through the international community has proven instrumental in positively influencing the direction of the IDN s development. The international community was instrumental in encouraging support for using the IS0 international character set that is now available through the directory. Supporting metadata descriptions in additional languages encourages extended use of the IDN. Temporal and spatial attributes often prove pivotal in the search for data. Prior to the new software release, the IDN s geospatial and temporal searches suffered from browser incompatibilities and often resulted in unreliable performance for users attempting to initiate a spatial search using a map based on aging Java applet technology. The IDN now offers an integrated Google map and date search that replaces that technology. In addition, one of the most defining characteristics in the search for data relates to the temporal and spatial resolution of the data. The ability to refine the search for data sets meeting defined resolution requirements is now possible. Data set authors are encouraged to indicate the precise resolution values for their data sets and subsequently bin these into one of the pre-selected resolution ranges. New metadata authoring tools have been well received. In response to requests for a standalone metadata authoring tool, a new shareable software package called "docBUILDER solo" will soon be released to the public. This tool permits researchers to document their data during experiments and observational periods in the field. interoperability has been enhanced through the use of the Open Archives Initiative s (OAI) Protocol for Metadata Harvesting (PMH). Harvesting of XML

  1. Microstructure and electroluminescent performance of chemical vapor deposited zinc sulfide doped with manganese films for integration in thin film electroluminescent devices

    NASA Astrophysics Data System (ADS)

    Topol, Anna Wanda

    Zinc sulfide (ZnS) doped with manganese (Mn), ZnS:Mn, is widely recognized as the brightest and most effective electroluminescent (EL) phosphor used in current thin film electroluminescent (TFEL) devices. ZnS acts as a host lattice for the luminescent activator, Mn, leading to a highly efficient yellow-orange EL emission, and resulting in a wide array of applications in monochrome, multi-color and full color displays. Although this wide band dap (3.7 eV) material can be prepared by several deposition techniques, the chemical vapor deposition (CVD) is the most promising for TFEL applications in terms of viable deposition rates, high thickness and composition uniformity, and excellent yield over large area panels. This study describes the development and optimization of a CVD ZnS:Mn process using diethylzinc [(C2H5)2Zn, DEZ], di-pi-cyclopentadienylmanganese [(C5H5)2Mn, CPMn], and hydrogen sulfide [H2S] as the chemical sources for, respectively, Zn, Mn, and S. The effects of key deposition parameters on resulting Film microstructure and performance are discussed, primarily in the context of identifying an optimized process window for best electroluminescence behavior. In particular, substrate temperature was observed to play a key role in the formation of high quality crystalline ZnS:Mn films leading to improved brightness and EL efficiency. Further investigations of the influence of temperature treatment on the structural characteristics and EL performance of the CVD ZnS:Mn film were carried out. In this study, the influence of post-deposition annealing both in-situ and ex-situ annealing processes, on chemical, structural, and electroluminescent characteristics of the phosphor layer are described. The material properties of the employed dielectric are among the key factors determining the performance, stability and reliability of the TFEL display and therefore, the choice of dielectric material for use in ACTFEL displays is crucial. In addition, the luminous

  2. Observation of frequency doubling in tantalum doped silica fibres

    NASA Technical Reports Server (NTRS)

    Driscoll, T. J.; Lawandy, N. M.; Killian, A.; Rienhart, L.; Morse, T. F.

    1991-01-01

    Second harmonic conversion efficients of 3 x 0,0001 in tantalum-doped silica fibers prepared by the seeding technique are reported. A series of experiments were conducted to characterize the frequency doubling in this fiber and to compare the results to the behavior observed in germanosilicate and rare earth-doped aluminosilicate fibers.

  3. Reducing Loss of Life and Property from Disasters: A Societal Benefit Area of the Strategic Plan for U.S. Integrated Earth Observation System (IEOS)

    USGS Publications Warehouse

    Helz, Rosalind L.; Gaynor, John E.

    2007-01-01

    Natural and technological disasters, such as hurricanes and other extreme weather events, earthquakes, volcanic eruptions, landslides and debris flows, wildland and urban-interface fires, floods, oil spills, and space-weather storms, impose a significant burden on society. Throughout the United States, disasters inflict many injuries and deaths, and cost the nation $20 billion each year (SDR, 2003). Disasters in other countries can affect U.S. assets and interests overseas (e.g. the eruption of Mt. Pinatubo in the Philippines, which effectively destroyed Clark Air Force Base). Also, because they have a disproportionate impact on developing countries, disasters are major barriers to sustainable development. Improving our ability to assess, predict, monitor, and respond to hazardous events is a key factor in reducing the occurrence and severity of disasters, and relies heavily on the use of information from well-designed and integrated Earth observation systems. To fully realize the benefits gained from the observation systems, the information derived must be disseminated through effective warning systems and networks, with products tailored to the needs of the end users and the general public.

  4. First steps of integrated spatial modeling of titanium, zirconium, and rare earth element resources within the Coastal Plain sediments of the southeastern United States

    USGS Publications Warehouse

    Ellefsen, Karl J.; Van Gosen, Bradley S.; Fey, David L.; Budahn, James R.; Smith, Steven M.; Shah, Anjana K.

    2015-01-01

    The Coastal Plain of the southeastern United States has extensive, unconsolidated sedimentary deposits that are enriched in heavy minerals containing titanium, zirconium, and rare earth element resources. Areas favorable for exploration and development of these resources are being identified by geochemical data, which are supplemented with geological, geophysical, hydrological, and geographical data. The first steps of this analysis have been completed. The concentrations of lanthanum, yttrium, and titanium tend to decrease as distance from the Piedmont (which is the likely source of these resources) increases and are moderately correlated with airborne measurements of equivalent thorium concentration. The concentrations of lanthanum, yttrium, and titanium are relatively high in those watersheds that adjoin the Piedmont, south of the Cape Fear Arch. Although this relation suggests that the concentrations are related to the watersheds, it may be simply an independent regional trend. The concentration of zirconium is unrelated to the distance from the Piedmont, the equivalent thorium concentration, and the watershed. These findings establish a foundation for more sophisticated analyses using integrated spatial modeling.

  5. Electrical, magnetic, and magneto-electrical properties in quasi-two-dimensional K{sub 0.58}RhO{sub 2} single crystals doped with rare-earth elements

    SciTech Connect

    Zhang, Bin-Bin; Dong, Song-Tao; Yao, Shu-Hua E-mail: ybchen@nju.edu.cn; Zhang, Shan-Tao; Gu, Zheng-Bin; Zhou, Jian; Lu, Ming-Hui; Chen, Yan-Feng; Chen, Y. B. E-mail: ybchen@nju.edu.cn; Shi, Y. G.

    2014-08-11

    In this Letter, we studied the electrical transport, magnetic property, magnetoresistance and anomalous Hall properties of La-, Sm-, Ho-, and Dy-doped quasi-two dimensional K{sub 0.58}RhO{sub 2} single crystals. At low temperature (<10 K), a significant magnetoresistance (36%) can be observed in these samples. Accordingly, the “glassy ferromagnetism” is revealed by temperature-dependent magnetization in these samples. The significant magnetoresistance is related to the granular ferromagnetism. The unconventional anomalous Hall effect is also observed in magnetic atoms doped samples. Our finding shields more light on the magnetic, magnetoresistance, and anomalous Hall properties of quasi-two-dimensional material systems doped with magnetic ions.

  6. Ceria co-doping: synergistic or average effect?

    PubMed

    Burbano, Mario; Nadin, Sian; Marrocchelli, Dario; Salanne, Mathieu; Watson, Graeme W

    2014-05-14

    Ceria (CeO2) co-doping has been suggested as a means to achieve ionic conductivities that are significantly higher than those in singly doped systems. Rekindled interest in this topic over the last decade has given rise to claims of much improved performance. The present study makes use of computer simulations to investigate the bulk ionic conductivity of rare earth (RE) doped ceria, where RE = Sc, Gd, Sm, Nd and La. The results from the singly doped systems are compared to those from ceria co-doped with Nd/Sm and Sc/La. The pattern that emerges from the conductivity data is consistent with the dominance of local lattice strains from individual defects, rather than the synergistic co-doping effect reported recently, and as a result, no enhancement in the conductivity of co-doped samples is observed. PMID:24658460

  7. Effect of ionic-size change of the rare earth ion on the electrical properties of the hole doped double perovskite Gd0.95Sr0.05BaCo2O5.5

    NASA Astrophysics Data System (ADS)

    Janaki, J.; Rajaji, V.; Kumary, T. Geetha; Kalavathi, S.; Bharathi, A.

    2013-02-01

    We report the effect of co-doping Y on the electrical properties of the hole doped double perovskite Gd0.95Sr0.05BaCo2O5.5. New compositions Gd0.95-xYxSr0.05BaCo2O5.5 have been successfully synthesized and characterized. A contraction in all three lattice parameters of the orthorhombic unit cell has been observed on Y doping. A reduction in the insulator to metal-like transition temperature (TIM) has been observed upon Y doping from 348K for x=0 to 331K for x=0.2. These observed shifts have been interpreted in terms of the possible mechanisms of the insulator-metal transition. The low temperature electrical resistivity data in the range 300-77K has been fitted to different conduction models. They fit best to a variable range hopping (VRH) model at low temperature below 120K followed by small polaron hopping model (SPH) at intermediate temperature (120-200K). The presence of magnetic polarons in the cobaltite systems has been envisaged recently and this provides further evidence for the same.

  8. Earth Science Informatics - Overview

    NASA Technical Reports Server (NTRS)

    Ramapriyan, H. K.

    2015-01-01

    Over the last 10-15 years, significant advances have been made in information management, there are an increasing number of individuals entering the field of information management as it applies to Geoscience and Remote Sensing data, and the field of informatics has come to its own. Informatics is the science and technology of applying computers and computational methods to the systematic analysis, management, interchange, and representation of science data, information, and knowledge. Informatics also includes the use of computers and computational methods to support decision making and applications. Earth Science Informatics (ESI, a.k.a. geoinformatics) is the application of informatics in the Earth science domain. ESI is a rapidly developing discipline integrating computer science, information science, and Earth science. Major national and international research and infrastructure projects in ESI have been carried out or are on-going. Notable among these are: the Global Earth Observation System of Systems (GEOSS), the European Commissions INSPIRE, the U.S. NSDI and Geospatial One-Stop, the NASA EOSDIS, and the NSF DataONE, EarthCube and Cyberinfrastructure for Geoinformatics. More than 18 departments and agencies in the U.S. federal government have been active in Earth science informatics. All major space agencies in the world, have been involved in ESI research and application activities. In the United States, the Federation of Earth Science Information Partners (ESIP), whose membership includes nearly 150 organizations (government, academic and commercial) dedicated to managing, delivering and applying Earth science data, has been working on many ESI topics since 1998. The Committee on Earth Observation Satellites (CEOS)s Working Group on Information Systems and Services (WGISS) has been actively coordinating the ESI activities among the space agencies. Remote Sensing; Earth Science Informatics, Data Systems; Data Services; Metadata

  9. An integrated study of earth resources in the state of California using remote sensing techniques. [planning and management of water resources

    NASA Technical Reports Server (NTRS)

    Colwell, R. N.; Churchman, C. W.; Burgy, R. H.; Schubert, G.; Estes, J. E.; Bowden, L. W.; Algazi, R.; Coulson, K. L. (Principal Investigator)

    1973-01-01

    The University of California has been conducting an investigation which seeks to determine the usefulness of modern remote sensing techniques for studying various components of California's earth resources complex. Most of the work has concentrated on California's water resources, but with some attention being given to other earth resources as well and to the interplay between them and California's water resources.

  10. Polar Misunderstandings: Earth's Dynamic Dynamo

    ERIC Educational Resources Information Center

    DiSpezio, Michael A.

    2011-01-01

    This article discusses the movement of Earth's north and south poles. The Earth's poles may be a bit more complex and dynamic than what many students and teachers believe. With better understanding, offer them up as a rich landscape for higher-level critical analysis and subject integration. Possible curriculum tie-ins include magnets, Earth…

  11. Measurements of defect structures by positron annihilation lifetime spectroscopy of the tellurite glass TeO2-P2O5-ZnO-LiNbO3 doped with ions of rare earth elements: Er3+, Nd3+ and Gd3+

    NASA Astrophysics Data System (ADS)

    Golis, E.; Yousef, El. S.; Reben, M.; Kotynia, K.; Filipecki, J.

    2015-12-01

    The objective of the study was the structural analysis of the TeO2-P2O5-ZnO-LiNbO3 tellurite glasses doped with ions of the rare-earth elements: Er3+, Nd3+ and Gd3+ based on the PALS (Positron Annihilation Lifetime Spectroscopy) method of measuring positron lifetimes. Values of positron lifetimes and the corresponding intensities may be connected with the sizes and number of structural defects, such as vacancies, mono-vacancies, dislocations or pores, the sizes of which range from a few angstroms to a few dozen nanometres. Experimental positron lifetime spectrum revealed existence of two positron lifetime components τ1 and τ2. Their interpretation was based on two-state positron trapping model where the physical parameters are the annihilation velocity and positron trapping rate.

  12. Synthesis and evaluation of ultra-pure rare-earth-coped glass for laser refrigeration

    SciTech Connect

    Patterson, Wendy M; Hehlen, Markus P; Epstein, Richard I; Sheik-bahae, Mansoor

    2009-01-01

    Significant progress has been made in synthesizing and characterizing ultra-pure, rare-earth doped ZIBLAN (ZrF{sub 4}-InF{sub 3}BaF{sub 2}-LaF{sub 3}-AlF{sub 3}-NaF) glass capable of laser refrigeration. The glass was produced from fluorides which were purified and subsequently treated with hydrofluoric gas at elevated temperatures to remove impurities before glass formation. Several Yb3 +-doped samples were studied with degrees of purity and composition with successive iterations producing an improved material. We have developed a non-invasive, spectroscopic technique, two band differential luminescence thermometry (TBDLT), to evaluate the intrinsic quality of the ytterbium doped ZIBLAN used for laser cooling experiments. TBDLT measures local temperature changes within an illuminated volume resulting solely from changes in the relative thermal population of the excited state levels. This TBDLT technique utilizes two commercially available band pass filters to select and integrate the 'difference regions' of interest in the luminescence spectra. The goal is to determine the minimum temperature to which the ytterbium sample can cool on the local scale, unphased by surface heating. This temperature where heating and cooling are exactly balanced is the zero crossing temperature (ZCT) and can be used as a measure for the presence of impurities and the overall quality of the laser cooling material. Overall, favorable results were obtained from 1 % Yb3+-doped glass, indicating our glasses are desirable for laser refrigeration.

  13. Strategy for earth explorers in global earth sciences

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The goal of the current NASA Earth System Science initiative is to obtain a comprehensive scientific understanding of the Earth as an integrated, dynamic system. The centerpiece of the Earth System Science initiative will be a set of instruments carried on polar orbiting platforms under the Earth Observing System program. An Earth Explorer program can open new vistas in the earth sciences, encourage innovation, and solve critical scientific problems. Specific missions must be rigorously shaped by the demands and opportunities of high quality science and must complement the Earth Observing System and the Mission to Planet Earth. The committee believes that the proposed Earth Explorer program provides a substantial opportunity for progress in the earth sciences, both through independent missions and through missions designed to complement the large scale platforms and international research programs that represent important national commitments. The strategy presented is intended to help ensure the success of the Earth Explorer program as a vital stimulant to the study of the planet.

  14. Google Earth Engine

    NASA Astrophysics Data System (ADS)

    Gorelick, N.

    2012-12-01

    The Google Earth Engine platform is a system designed to enable petabyte-scale, scientific analysis and visualization of geospatial datasets. Earth Engine provides a consolidated environment including a massive data catalog co-located with thousands of computers for analysis. The user-friendly front-end provides a workbench environment to allow interactive data and algorithm development and exploration and provides a convenient mechanism for scientists to share data, visualizations and analytic algorithms via URLs. The Earth Engine data catalog contains a wide variety of popular, curated datasets, including the world's largest online collection of Landsat scenes (> 2.0M), numerous MODIS collections, and many vector-based data sets. The platform provides a uniform access mechanism to a variety of data types, independent of their bands, projection, bit-depth, resolution, etc..., facilitating easy multi-sensor analysis. Additionally, a user is able to add and curate their own data and collections. Using a just-in-time, distributed computation model, Earth Engine can rapidly process enormous quantities of geo-spatial data. All computation is performed lazily; nothing is computed until it's required either for output or as input to another step. This model allows real-time feedback and preview during algorithm development, supporting a rapid algorithm development, test, and improvement cycle that scales seamlessly to large-scale production data processing. Through integration with a variety of other services, Earth Engine is able to bring to bear considerable analytic and technical firepower in a transparent fashion, including: AI-based classification via integration with Google's machine learning infrastructure, publishing and distribution at Google scale through integration with the Google Maps API, Maps Engine and Google Earth, and support for in-the-field activities such as validation, ground-truthing, crowd-sourcing and citizen science though the Android Open Data

  15. Google Earth Engine

    NASA Astrophysics Data System (ADS)

    Gorelick, Noel

    2013-04-01

    The Google Earth Engine platform is a system designed to enable petabyte-scale, scientific analysis and visualization of geospatial datasets. Earth Engine provides a consolidated environment including a massive data catalog co-located with thousands of computers for analysis. The user-friendly front-end provides a workbench environment to allow interactive data and algorithm development and exploration and provides a convenient mechanism for scientists to share data, visualizations and analytic algorithms via URLs. The Earth Engine data catalog contains a wide variety of popular, curated datasets, including the world's largest online collection of Landsat scenes (> 2.0M), numerous MODIS collections, and many vector-based data sets. The platform provides a uniform access mechanism to a variety of data types, independent of their bands, projection, bit-depth, resolution, etc..., facilitating easy multi-sensor analysis. Additionally, a user is able to add and curate their own data and collections. Using a just-in-time, distributed computation model, Earth Engine can rapidly process enormous quantities of geo-spatial data. All computation is performed lazily; nothing is computed until it's required either for output or as input to another step. This model allows real-time feedback and preview during algorithm development, supporting a rapid algorithm development, test, and improvement cycle that scales seamlessly to large-scale production data processing. Through integration with a variety of other services, Earth Engine is able to bring to bear considerable analytic and technical firepower in a transparent fashion, including: AI-based classification via integration with Google's machine learning infrastructure, publishing and distribution at Google scale through integration with the Google Maps API, Maps Engine and Google Earth, and support for in-the-field activities such as validation, ground-truthing, crowd-sourcing and citizen science though the Android Open Data

  16. "In These Shoes Is the Silent Call of the Earth": Meditations on Curriculum Integration, Conceptual Violence, and the Ecologies of Community and Place.

    ERIC Educational Resources Information Center

    Jardine, David W.; LaGrange, Annette; Everest, Beth

    1998-01-01

    Explores some current concepts of curriculum integration, and proposes some alternatives to the conceptual violence often done in the name of curriculum integration. What is lost in many efforts in curriculum integration is the "topography" of any particular thing. Curriculum integration should rely on relationships that already exist and not…

  17. From Land Use to Land Cover: Restoring the Afforestation Signal in a Coupled Integrated Assessment - Earth System Model and the Implications for CMIP5 RCP Simulations

    NASA Astrophysics Data System (ADS)

    Di Vittorio, A. V.; Chini, L. P.; Bond-Lamberty, B. P.; Mao, J.; Shi, X.; Truesdale, J. E.; Craig, A.; Calvin, K. V.; Jones, A. D.; Collins, W.; Edmonds, J.; Hurtt, G. C.; Thornton, P. E.; Thomson, A. M.

    2014-12-01

    Climate projections depend on scenarios of fossil fuel emissions and land use change, and the IPCC AR5 parallel process assumes consistent climate scenarios across Integrated Assessment and Earth System Models (IAMs and ESMs). The CMIP5 project used a novel "land use harmonization" based on the Global Land use Model (GLM) to provide ESMs with consistent 1500-2100 land use trajectories generated by historical data and four IAM projections. A direct coupling of the Global Change Assessment Model (GCAM), GLM, and the Community ESM (CESM) has allowed us to characterize and partially address a major gap in the CMIP5 land coupling design: the lack of a corresponding land cover harmonization. The CMIP5 CESM global afforestation is only 22% of GCAM's 2005 to 2100 RCP4.5 afforestation. Likewise, only 17% of GCAM's 2040 RCP4.5 afforestation, and zero pasture loss, were transmitted to CESM within the directly coupled model. This is a problem because afforestation was relied upon to achieve RCP4.5 climate stabilization. GLM modifications within the directly coupled model did not increase CESM afforestation. Modifying the CESM land use translator in addition to GLM, however, enabled CESM to simulate 66% of GCAM's afforestation in 2040, and 94% of GCAM's pasture loss as grassland and shrubland losses. This additional afforestation increases vegetation carbon gain by 19 PgC and decreases atmospheric CO2 gain by 8 ppmv from 2005 to 2040, implying different RCP4.5 climate scenarios between CMIP5 GCAM and CESM. Although the IAMs and ESMs were not expected to have exactly the same climate forcing, due in part to different terrestrial carbon cycles and atmospheric radiation algorithms, the ESMs were expected to project climates representative of the RCP scenarios. Similar land cover inconsistencies exist in other CMIP5 model results, primarily because land cover information is not shared between IAM and ESM models. High RCP4.5 afforestation might also contribute to inconsistencies as

  18. Discover Earth

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Discover Earth is a NASA-funded project for teachers of grades 5-12 who want to expand their knowledge of the Earth system, and prepare to become master teachers who promote Earth system science in their own schools, counties, and throughout their state. Participants from the following states are invited to apply: Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and Washington, DC. Teachers selected for the project participate in a two-week summer workshop conducted at the University of Maryland, College Park; develop classroom-ready materials during the workshop for broad dissemination; conduct a minimum of two peer training activities during the coming school year; and participate in other enrichment/education opportunities as available and desired. Discover Earth is a team effort that utilizes expertise from a range of contributors, and balances science content with hands-on classroom applications.

  19. Discover Earth

    NASA Technical Reports Server (NTRS)

    Steele, Colleen

    1996-01-01

    Discover Earth is a NASA-funded project for teachers of grades 5-12 who want to expand their knowledge of the Earth system, and prepare to become master teachers who promote Earth system science in their own schools, counties, and throughout their state. Participants from the following states are invited to apply: Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and Washington, DC. Teachers selected for the project participate in a two-week summer workshop conducted at the University of Maryland, College Park; develop classroom-ready materials during the workshop for broad dissemination; conduct a minimum of two peer training activities during the coming school year; and participate in other enrichment/education opportunities as available and desired. Discover Earth is a team effort that utilizes expertise from a range of contributors, and balances science content with hands-on classroom applications.

  20. Earth Rotation

    NASA Technical Reports Server (NTRS)

    Dickey, Jean O.

    1995-01-01

    The study of the Earth's rotation in space (encompassing Universal Time (UT1), length of day, polar motion, and the phenomena of precession and nutation) addresses the complex nature of Earth orientation changes, the mechanisms of excitation of these changes and their geophysical implications in a broad variety of areas. In the absence of internal sources of energy or interactions with astronomical objects, the Earth would move as a rigid body with its various parts (the crust, mantle, inner and outer cores, atmosphere and oceans) rotating together at a constant fixed rate. In reality, the world is considerably more complicated, as is schematically illustrated. The rotation rate of the Earth's crust is not constant, but exhibits complicated fluctuations in speed amounting to several parts in 10(exp 8) [corresponding to a variation of several milliseconds (ms) in the Length Of the Day (LOD) and about one part in 10(exp 6) in the orientation of the rotation axis relative to the solid Earth's axis of figure (polar motion). These changes occur over a broad spectrum of time scales, ranging from hours to centuries and longer, reflecting the fact that they are produced by a wide variety of geophysical and astronomical processes. Geodetic observations of Earth rotation changes thus provide insights into the geophysical processes illustrated, which are often difficult to obtain by other means. In addition, these measurements are required for engineering purposes. Theoretical studies of Earth rotation variations are based on the application of Euler's dynamical equations to the problem of finding the response of slightly deformable solid Earth to variety of surface and internal stresses.

  1. Angle-Dependent Microresonator ESR Characterization of Locally Doped Gd3 + :Al2O3

    NASA Astrophysics Data System (ADS)

    Wisby, I. S.; de Graaf, S. E.; Gwilliam, R.; Adamyan, A.; Kubatkin, S. E.; Meeson, P. J.; Tzalenchuk, A. Ya.; Lindström, T.

    2016-08-01

    Interfacing rare-earth-doped crystals with superconducting circuit architectures provides an attractive platform for quantum memory and transducer devices. Here, we present the detailed characterization of such a hybrid system: a locally implanted rare-earth Gd3 + in Al2O3 spin system coupled to a superconducting microresonator. We investigate the properties of the implanted spin system through angular-dependent microresonator electron spin resonance (micro-ESR) spectroscopy. We find, despite the high-energy near-surface implantation, the resulting micro-ESR spectra to be in excellent agreement with the modeled Hamiltonian, supporting the integration of dopant ions into their relevant lattice sites while maintaining crystalline symmetries. Furthermore, we observe clear contributions from individual microwave field components of our microresonator, emphasizing the need for controllable local implantation.

  2. Integrating planar waveguides doped with light scattering nanoparticles into a flat-plate photobioreactor to improve light distribution and microalgae growth.

    PubMed

    Sun, Yahui; Liao, Qiang; Huang, Yun; Xia, Ao; Fu, Qian; Zhu, Xun; Zheng, Yaping

    2016-11-01

    Industrially manufactured planar waveguides doped with light scattering nanoparticles, which can dilute and redistribute the intense incident light within microalgae suspension more uniformly, were introduced into a flat-plate photobioreactor (PBR) with a width of 25cm to alleviate the adverse effect of poor light penetrability on microalgae growth. Compared with the flat-plate PBR without waveguides, the illumination surface area per unit volume in the proposed PBR was increased by 10.3 times. During the whole cultivation period, the illuminated volume fractions in the proposed PBR were 21.4-410% higher than those in the flat-plate PBR without waveguides. Consequently, attributed to the optimized light distribution in the proposed PBR, a 220% improvement in biomass production was obtained relative to that in the flat-plate PBR without waveguides. Furthermore, higher light output intensities emitted from the planar waveguide surfaces and increased microalgae growth rates were achieved by decreasing the length of planar waveguides.

  3. Integrating planar waveguides doped with light scattering nanoparticles into a flat-plate photobioreactor to improve light distribution and microalgae growth.

    PubMed

    Sun, Yahui; Liao, Qiang; Huang, Yun; Xia, Ao; Fu, Qian; Zhu, Xun; Zheng, Yaping

    2016-11-01

    Industrially manufactured planar waveguides doped with light scattering nanoparticles, which can dilute and redistribute the intense incident light within microalgae suspension more uniformly, were introduced into a flat-plate photobioreactor (PBR) with a width of 25cm to alleviate the adverse effect of poor light penetrability on microalgae growth. Compared with the flat-plate PBR without waveguides, the illumination surface area per unit volume in the proposed PBR was increased by 10.3 times. During the whole cultivation period, the illuminated volume fractions in the proposed PBR were 21.4-410% higher than those in the flat-plate PBR without waveguides. Consequently, attributed to the optimized light distribution in the proposed PBR, a 220% improvement in biomass production was obtained relative to that in the flat-plate PBR without waveguides. Furthermore, higher light output intensities emitted from the planar waveguide surfaces and increased microalgae growth rates were achieved by decreasing the length of planar waveguides. PMID:27573475

  4. Photosynthesis and early Earth.

    PubMed

    Shih, Patrick M

    2015-10-01

    Life has been built on the evolution and innovation of microbial metabolisms. Even with our scant understanding of the full diversity of microbial life, it is clear that microbes have become integral components of the biogeochemical cycles that drive our planet. The antiquity of life further suggests that various microbial metabolisms have been core and essential to global elemental cycling for a majority of Earth's history.

  5. Digital Earth - A sustainable Earth

    NASA Astrophysics Data System (ADS)

    Mahavir

    2014-02-01

    All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth.

  6. Celebrate the Earth...Every Day!

    ERIC Educational Resources Information Center

    Laubenthal, Gail

    1995-01-01

    Discusses the importance of teaching young children to appreciate and care for the earth and how to integrate earth activities into the curriculum. Includes a year-round curriculum with ideas for hands-on activities appropriate to each month, an integrated unit called "Flowers Blooming," tips for evaluating science experiences, and a list of…

  7. Earth Algebra.

    ERIC Educational Resources Information Center

    Schaufele, Christopher; Zumoff, Nancy

    Earth Algebra is an entry level college algebra course that incorporates the spirit of the National Council of Teachers of Mathematics (NCTM) Curriculum and Evaluation Standards for School Mathematics at the college level. The context of the course places mathematics at the center of one of the major current concerns of the world. Through…

  8. Rare earths

    USGS Publications Warehouse

    Gambogi, J.

    2013-01-01

    Global mine production of rare earths was estimated to have declined slightly in 2012 relative to 2011 (Fig. 1). Production in China was estimated to have decreased to 95 from 105 kt (104,700 from 115,700 st) in 2011, while new mine production in the United States and Australia increased.

  9. Think Earth.

    ERIC Educational Resources Information Center

    Niedermeyer, Fred; Ice, Kay

    1992-01-01

    Describes a series of environmental education instructional units for grades K-6 developed by the Think Earth Consortium that cover topics such as conservation, pollution control, and waste reduction. Provides testimony from one sixth-grade teacher that field tested the second-grade unit. (MDH)

  10. Optical properties and chemical composition analyses of mixed rare earth oxyorthosilicate (R2SiO5, R=La, Gd and Y) doped Dy3+ phosphors prepared by urea-assisted solution combustion method

    NASA Astrophysics Data System (ADS)

    Ogugua, S. N.; Shaat, S. K. K.; Swart, H. C.; Ntwaeaborwa, O. M.

    2015-08-01

    Dysprosium (Dy3+) doped lanthanum gadolinium oxyorthosilicate (LaGdSiO5), lanthanum yttrium oxyorthosilicate (LaYSiO5) and gadolinium yttrium oxyorthosilicate (GdYSiO5) phosphors (in powder form) were synthesized by urea-assisted combustion method. The X-ray diffractometer analysis confirmed that the LaGdSiO5, LaYSiO5 and GdYSiO5 crystalized in monoclinic phases. The chemical composition of the phosphors was analyzed by measuring the atomic and molecular ionic species using the time of flight secondary ion mass spectroscopy (ToF SIMS). In addition, ToF SIMS imaging technique was used to determine the distribution of the Dy3+ dopant ions on the surface on the phosphors. The average crystallite sizes and lattice strains of the phosphor were increased by Dy3+ doping. The field emission scanning electron microscope images showed that the powders were made up of an agglomeration of particles with no regular shape. The photoluminescence data showed narrow line emission peaks at the wavelengths of 485 nm (minor emission) and 573 nm (major emission) associated with the f→f transitions of Dy3+. The photoluminescence (PL) measurements showed that the emission peak of LaGdSiO5:Dy3+ was ~3× more intense than those of LaYSiO5:Dy3+ and GdYSiO5:Dy3+ when excited using monochromatic xenon lamp with a wavelength of 241 nm. However, when the powders were excited using a 325 nm He-Cd laser, the highest PL emission intensity was observed from GdYSiO5:Dy3+.

  11. A first principles study of Nd doped cubic LaAlO3 perovskite: mBJ+U study

    NASA Astrophysics Data System (ADS)

    Sandeep; Rai, D. P.; Shankar, A.; Ghimire, M. P.; Khenata, R.; Thapa, R. K.

    2016-11-01

    The structural, electronic and magnetic properties of Nd-doped Rare earth aluminate, La1-xNdxAlO3 (x=0-100%) are studied using the full potential linearized augmented plane-wave (FP-LAPW) method within the density functional theory. The effects of Nd substitution in LaAlO3 are studied using super-cell calculations. The electronic structures were computed using modified Beck Johnson (mBJ) potential based approximation with the inclusion of Coulomb energy (U) for Nd-4f state electrons. The La1-xNdxAlO3 may possess half metallic behavior on Nd doping with finite density of states at EF. The direct and indirect band gaps were studied as a function of Nd concentration in LaAlO3. The calculated magnetic moments in La1-xNdxAlO3 were found to arise mainly from the Nd-4f state electrons. A probable half-metallic nature is suggested for these systems with supportive integral magnetic moments and high spin polarized electronic structures in these doped cases at EF. The controlled decrease in band gap with increase in concentration of Nd doping is a suitable technique for harnessing useful spintronic and magnetic devices.

  12. Faraday rotation and photoluminescence in heavily Tb3+-doped GeO2-B2O3-Al2O3-Ga2O3 glasses for fiber-integrated magneto-optics

    PubMed Central

    Gao, Guojun; Winterstein-Beckmann, Anja; Surzhenko, Oleksii; Dubs, Carsten; Dellith, Jan; Schmidt, Markus A.; Wondraczek, Lothar

    2015-01-01

    We report on the magneto-optical (MO) properties of heavily Tb3+-doped GeO2-B2O3-Al2O3-Ga2O3 glasses towards fiber-integrated paramagnetic MO devices. For a Tb3+ ion concentration of up to 9.7 × 1021 cm−3, the reported glass exhibits an absolute negative Faraday rotation of ~120 rad/T/m at 632.8 nm. The optimum spectral ratio between Verdet constant and light transmittance over the spectral window of 400–1500 nm is found for a Tb3+ concentration of ~6.5 × 1021 cm−3. For this glass, the crystallization stability, expressed as the difference between glass transition temperature and onset temperature of melt crystallization exceeds 100 K, which is a prerequisite for fiber drawing. In addition, a high activation energy of crystallization is achieved at this composition. Optical absorption occurs in the NUV and blue spectral region, accompanied by Tb3+ photoluminescence. In the heavily doped materials, a UV/blue-to-green photo-conversion gain of ~43% is achieved. The lifetime of photoluminescence is ~2.2 ms at a stimulated emission cross-section σem of ~1.1 × 10−21 cm2 for ~ 5.0 × 1021 cm−3 Tb3+. This results in an optical gain parameter σem*τ of ~2.5 × 10−24 cm2s, what could be of interest for implementation of a Tb3+ fiber laser. PMID:25754819

  13. Faraday rotation and photoluminescence in heavily Tb(3+)-doped GeO2-B2O3-Al2O3-Ga2O3 glasses for fiber-integrated magneto-optics.

    PubMed

    Gao, Guojun; Winterstein-Beckmann, Anja; Surzhenko, Oleksii; Dubs, Carsten; Dellith, Jan; Schmidt, Markus A; Wondraczek, Lothar

    2015-03-10

    We report on the magneto-optical (MO) properties of heavily Tb(3+)-doped GeO2-B2O3-Al2O3-Ga2O3 glasses towards fiber-integrated paramagnetic MO devices. For a Tb(3+) ion concentration of up to 9.7 × 10(21) cm(-3), the reported glass exhibits an absolute negative Faraday rotation of ~120 rad/T/m at 632.8 nm. The optimum spectral ratio between Verdet constant and light transmittance over the spectral window of 400-1500 nm is found for a Tb(3+) concentration of ~6.5 × 10(21) cm(-3). For this glass, the crystallization stability, expressed as the difference between glass transition temperature and onset temperature of melt crystallization exceeds 100 K, which is a prerequisite for fiber drawing. In addition, a high activation energy of crystallization is achieved at this composition. Optical absorption occurs in the NUV and blue spectral region, accompanied by Tb(3+) photoluminescence. In the heavily doped materials, a UV/blue-to-green photo-conversion gain of ~43% is achieved. The lifetime of photoluminescence is ~2.2 ms at a stimulated emission cross-section σem of ~1.1 × 10(-21) cm(2) for ~ 5.0 × 10(21) cm(-3) Tb(3+). This results in an optical gain parameter σem*τ of ~2.5 × 10(-24) cm(2)s, what could be of interest for implementation of a Tb(3+) fiber laser.

  14. Faraday rotation and photoluminescence in heavily Tb3+-doped GeO2-B2O3-Al2O3-Ga2O3 glasses for fiber-integrated magneto-optics

    NASA Astrophysics Data System (ADS)

    Gao, Guojun; Winterstein-Beckmann, Anja; Surzhenko, Oleksii; Dubs, Carsten; Dellith, Jan; Schmidt, Markus A.; Wondraczek, Lothar

    2015-03-01

    We report on the magneto-optical (MO) properties of heavily Tb3+-doped GeO2-B2O3-Al2O3-Ga2O3 glasses towards fiber-integrated paramagnetic MO devices. For a Tb3+ ion concentration of up to 9.7 × 1021 cm-3, the reported glass exhibits an absolute negative Faraday rotation of ~120 rad/T/m at 632.8 nm. The optimum spectral ratio between Verdet constant and light transmittance over the spectral window of 400-1500 nm is found for a Tb3+ concentration of ~6.5 × 1021 cm-3. For this glass, the crystallization stability, expressed as the difference between glass transition temperature and onset temperature of melt crystallization exceeds 100 K, which is a prerequisite for fiber drawing. In addition, a high activation energy of crystallization is achieved at this composition. Optical absorption occurs in the NUV and blue spectral region, accompanied by Tb3+ photoluminescence. In the heavily doped materials, a UV/blue-to-green photo-conversion gain of ~43% is achieved. The lifetime of photoluminescence is ~2.2 ms at a stimulated emission cross-section σem of ~1.1 × 10-21 cm2 for ~ 5.0 × 1021 cm-3 Tb3+. This results in an optical gain parameter σem*τ of ~2.5 × 10-24 cm2s, what could be of interest for implementation of a Tb3+ fiber laser.

  15. Earth meandering

    NASA Astrophysics Data System (ADS)

    Asadiyan, H.; Zamani, A.

    2009-04-01

    In this paper we try to put away current Global Tectonic Model to look the tectonic evolution of the earth from new point of view. Our new dynamic model is based on study of river meandering (RM) which infer new concept as Earth meandering(EM). In a universal gravitational field if we consider a clockwise spiral galaxy model rotate above Ninety East Ridge (geotectonic axis GA), this system with applying torsion field (likes geomagnetic field) in side direction from Rocky Mt. (west geotectonic pole WGP) to Tibetan plateau TP (east geotectonic pole EGP),it seems that pulled mass from WGP and pushed it in EGP due to it's rolling dynamics. According to this idea we see in topographic map that North America and Green land like a tongue pulled from Pacific mouth toward TP. Actually this system rolled or meander the earth over itself fractaly from small scale to big scale and what we see in the river meandering and Earth meandering are two faces of one coin. River transport water and sediments from high elevation to lower elevation and also in EM, mass transport from high altitude-Rocky Mt. to lower altitude Himalaya Mt. along 'S' shape geodetic line-optimum path which connect points from high altitude to lower altitude as kind of Euler Elastica(EE). These curves are responsible for mass spreading (source) and mass concentration (sink). In this regard, tiltness of earth spin axis plays an important role, 'S' are part of sigmoidal shape which formed due to intersection of Earth rolling with the Earth glob and actual feature of transform fault and river meandering. Longitudinal profile in mature rivers as a part of 'S' curve also is a kind of EE. 'S' which bound the whole earth is named S-1(S order 1) and cube corresponding to this which represent Earth fracturing in global scale named C-1(cube order 1 or side vergence cube SVC), C-1 is a biggest cycle of spiral polygon, so it is not completely closed and it has separation about diameter of C-7. Inside SVC we introduce cone

  16. NiCo2S4 nanotube arrays grown on flexible nitrogen-doped carbon foams as three-dimensional binder-free integrated anodes for high-performance lithium-ion batteries.

    PubMed

    Wu, Xiaoyu; Li, Songmei; Wang, Bo; Liu, Jianhua; Yu, Mei

    2016-02-14

    Binary metal sulfides, especially NiCo2S4, hold great promise as anode materials for high-performance lithium-ion batteries because of their excellent electronic conductivity and high capacity compared to mono-metal sulfides and oxides. Here, NiCo2S4 nanotube arrays are successfully grown on flexible nitrogen-doped carbon foam (NDCF) substrates with robust adhesion via a facile surfactant-assisted hydrothermal route and the subsequent sulfurization treatment. The obtained NiCo2S4/NDCF composites show unique three-dimensional architectures, in which NiCo2S4 nanotubes of ∼5 μm in length and 100 nm in width are uniformly grown on the NDCF skeletons to form arrays. When used directly as integrated anodes for lithium-ion batteries without any conductive additives and binders, the NiCo2S4/NDCF composites exhibit a high reversible capacity of 1721 mA h g(-1) at a high current density of 500 mA g(-1), enhanced cycling performance with the capacity maintained at 1182 mA h g(-1) after 100 cycles, and a remarkable rate capability. The excellent lithium storage performances of the composites could be attributed to the unique material composition, a rationally designed hollow nanostructure and an integrated smart architecture, which offer fast electron transport and ion diffusion, enhanced material/-electrolyte contact area and facile accommodation of strains during the lithium insertion and extraction process.

  17. Upconversion luminescence in Yb 3+-doped yttrium aluminum garnets

    NASA Astrophysics Data System (ADS)

    Xu, Xiaodong; Zhao, Zhiwei; Song, Pingxin; Jiang, Benxue; Zhou, Guoqing; Xu, Jun; Deng, Peizhen; Bourdet, Gilbert; Christophe Chanteloup, Jean; Zou, Ji-Ping; Fulop, Annabelle

    2005-03-01

    In this paper, we present results on upconversion luminescence performed on Yb 3+-doped yttrium aluminum garnets under 940 nm excitation. The upconversion luminescence was ascribed to Yb 3+ cooperative luminescence and the presence of rare earth impurity ions. The cooperative luminescence spectra as a function of Yb concentration were measured and the emission intensity variation with Yb concentration was discussed. Yb 3+ energy migration quenched the cooperative luminescence of Yb:YAG crystals with doping level over 15 at%.

  18. Computational discovery of lanthanide doped and Co-doped Y{sub 3}Al{sub 5}O{sub 12} for optoelectronic applications

    SciTech Connect

    Choudhary, Kamal; Chernatynskiy, Aleksandr; Phillpot, Simon R.; Sinnott, Susan B.; Mathew, Kiran; Bucholz, Eric W.; Hennig, Richard G.

    2015-09-14

    We systematically elucidate the optoelectronic properties of rare-earth doped and Ce co-doped yttrium aluminum garnet (YAG) using hybrid exchange-correlation functional based density functional theory. The predicted optical transitions agree with the experimental observations for single doped Ce:YAG, Pr:YAG, and co-doped Er,Ce:YAG. We find that co-doping of Ce-doped YAG with any lanthanide except Eu and Lu lowers the transition energies; we attribute this behavior to the lanthanide-induced change in bonding environment of the dopant atoms. Furthermore, we find infrared transitions only in case of the Er, Tb, and Tm co-doped Ce:YAG and suggest Tm,Ce:YAG and Tb,Ce:YAG as possible functional materials for efficient spectral up-conversion devices.

  19. Erbium doped tellurite photonic crystal optical fiber

    NASA Astrophysics Data System (ADS)

    Osorio, Sergio P.; Fernandez, Enver; Rodriguez, Eugenio; Cesar, Carlos L.; Barbosa, Luiz C.

    2005-04-01

    In this work we present the fabrication of tellurite glass photonic crystal fiber doped with a very large erbium concentration. Tellurite glasses are important hosts for rare earth ions due to its very high solubility, which allows up to 10,000 ppm Er3+ concentrations. The photonic crystal optical fibers and tellurite glasses can be, therefore, combined in an efficient way to produce doped fibers for large bandwidth optical amplifiers. The preform was made of a 10 mm external diameter tellurite tube filled with an array of non-periodic tellurite capillaries and an erbium-doped telluride rod that constitute the fiber core. The preform was drawn in a Heathway Drawing Tower, producing fibers with diameters between 120 - 140 μm. We show optical microscope photography of the fiber"s transverse section. The ASE spectra obtained with a spectra analyzer show a red shift as the length of the optical fiber increases.

  20. Influence of high magnetic field on the luminescence of Eu{sup 3+}-doped glass ceramics

    SciTech Connect

    Jiang, Wei; Chen, Weibo; Chen, Ping; Xu, Beibei; Zheng, Shuhong; Guo, Qiangbing; Liu, Xiaofeng E-mail: qjr@zju.edu.cn; Zhang, Junpei; Han, Junbo; Qiu, Jianrong E-mail: qjr@zju.edu.cn

    2014-09-28

    Rare earth (RE) doped materials have been widely exploited as the intriguing electronic configuration of RE ions offers diverse functionalities from optics to magnetism. However, the coupling of magnetism with photoluminescence (PL) in such materials has been rarely reported in spite of its fundamental significance. In the present paper, the effect of high pulsed magnetic field on the photoluminescence intensity of Eu{sup 3+}-doped nano-glass-ceramics has been investigated. In our experiment, Eu-doped oxyfluoride glass and glass ceramic were prepared by the conventional melt-quenching process and controlled heat treatment. The results demonstrate that the integrated PL intensity of Eu{sup 3+} decreases with the enhancement of magnetic field, which can be interpreted in terms of cooperation effect of Zeeman splitting and magnetic field induced change in site symmetry. Furthermore, as a result of Zeeman splitting, both blue and red shift in the emission peaks of Eu{sup 3+} can be observed, and this effect becomes more prominent with the increase of magnetic field. Possible mechanisms associated with the observed magneto-optical behaviors are suggested. The results of the present paper may open a new gate for modulation of luminescence by magnetic field and remote optical detection of magnetic field.

  1. Rotation of a Moonless Earth

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Barnes, Jason W.; Chambers, John E.

    2013-01-01

    We numerically explore the obliquity (axial tilt) variations of a hypothetical moonless Earth. Previous work has shown that the Earth's Moon stabilizes Earth's obliquity such that it remains within a narrow range, between 22.1 deg and 24.5 deg. Without lunar influence, a frequency-map analysis by Laskar et al. showed that the obliquity could vary between 0 deg. and 85 deg. This has left an impression in the astrobiology community that a large moon is necessary to maintain a habitable climate on an Earth-like planet. Using a modified version of the orbital integrator mercury, we calculate the obliquity evolution for moonless Earths with various initial conditions for up to 4 Gyr. We find that while obliquity varies significantly more than that of the actual Earth over 100,000 year timescales, the obliquity remains within a constrained range, typically 20-25 deg. in extent, for timescales of hundreds of millions of years. None of our Solar System integrations in which planetary orbits behave in a typical manner show obliquity accessing more than 65% of the full range allowed by frequency-map analysis. The obliquities of moonless Earths that rotate in the retrograde direction are more stable than those of pro-grade rotators. The total obliquity range explored for moonless Earths with rotation periods shorter than 12 h is much less than that for slower-rotating moonless Earths. A large moon thus does not seem to be needed to stabilize the obliquity of an Earth-like planet on timescales relevant to the development of advanced life.

  2. Integrated Science.

    ERIC Educational Resources Information Center

    Rainey, Larry; Miller, Roxanne Greitz

    1997-01-01

    Describes the Integrated Science program that integrates biology, earth/space science, chemistry, and physics over a three-year, spiraling sequence arranged around broad themes such as cycles, changes, patterns, and waves. Includes weekly telecasts via public television and satellite, teacher manuals, student handbooks, e-mail connections, staff…

  3. Well-width dependence of optical properties of rare-earth ion-doped ZnS0.8Se0.2/undoped ZnS multiple quantum wells

    NASA Astrophysics Data System (ADS)

    Tanaka, Masanori; Yamada, Hisashi; Maruyama, Takahiro; Akimoto, Katsuhiro

    2003-01-01

    We compare optical properties of Sm3+-doped ZnS0.8Se0.2/undoped ZnS multiple-quantum wells (MQWs) with different well widths (2, 5, 10 monolayers) and bulk ZnS0.8Se0.2:Sm3+ crystal. The excitonic peak in the photoluminescence excitation spectrum of the Sm3+ luminescence shifts to the shorter-wavelength side with reducing well width, which shows that the excitation of Sm3+ occurs through the energy transfer from the spatially confined excitons. The activation energy of the thermal quenching of the Sm3+ luminescence is found to increase with reducing well width. This result is interpreted as due to the difference in the spatial confinement effect on the binding energy of the free exciton. In addition, the quantum efficiency of the Sm3+ luminescence at 4 K is found to increase remarkably with reducing well width. At this temperature, the quantum efficiency of the two monolayers MQW sample is more than 16 times as high as that of the bulk sample. Probable causes of this fact are discussed.

  4. Highly ytterbium-doped silica fibers with low photo-darkening.

    PubMed

    Suzuki, Shigeru; McKay, Hugh A; Peng, Xiang; Fu, Libin; Dong, Liang

    2009-06-01

    Phosphorus co-doping is known to reduce clustering levels of rare earth ions in silica hosts. In this paper, ytterbium-doped silica fibers with approximately 8.9 wt% Yb(2)O(3), up to approximately 4700 dB/m peak core absorption at 976 nm, and low photo-darkening are demonstrated using high phosphorus co-doping. Measured gain as high as approximately 7 dB/cm is demonstrated in the fiber. PMID:19506642

  5. Highly ytterbium-doped silica fibers with low photo-darkening.

    PubMed

    Suzuki, Shigeru; McKay, Hugh A; Peng, Xiang; Fu, Libin; Dong, Liang

    2009-06-01

    Phosphorus co-doping is known to reduce clustering levels of rare earth ions in silica hosts. In this paper, ytterbium-doped silica fibers with approximately 8.9 wt% Yb(2)O(3), up to approximately 4700 dB/m peak core absorption at 976 nm, and low photo-darkening are demonstrated using high phosphorus co-doping. Measured gain as high as approximately 7 dB/cm is demonstrated in the fiber.

  6. Committing to creating time for integrating contemporary environmental issues into a traditional introduction to Earth Science course, one topic at a time

    NASA Astrophysics Data System (ADS)

    Cook, H. M.

    2014-12-01

    I teach an Earth Science course, designed as an introductory science class that also fulfills the Earth Science requirement for pre-service teachers preparing to take their state content exam. This course provides an introduction to astronomy, geology, oceanography, and meteorology. By design, the class is content-heavy. Despite this, with so many current environmental and societal issues directly tied to the Earth Sciences, it is essential to address contemporary problems and to educate students about the changes and challenges in the world around them. I have made a commitment to doing this by incorporating relevant societal and environmental issues into every topic and every class session. While this may sound basic, doing so requires diligence and research. For example, when teaching about weathering and erosion, I discuss soils, soil quality and erosion, and the impact this has on our global food supply. A hands-on mineral activity lends itself to looking at the energy and waste involved in ore extraction. A lecture on ocean circulation results in an opportunity to analyze the consequences of the interruption of this pattern due to global warming. Through this approach, students are provided with necessary content; furthermore, by linking traditional content to modern issues on a regular basis, students see the relevance of what they are learning and become more aware of the environmental issues facing society today. Student evaluations indicate that this approach has been successful: 100% of students reported that they learned a great deal from the course, and 100% of students agreed that the quality of the course was high. In addition, prior to the class 55.8% of the students indicated interested in the content; whereas, after the course 88.6% indicated interest, with strong interest in the content increasing from 16.3% to 41%.

  7. An Integrative Approach to Improving an Introductory Weather & Climate Course and Developing an Allied NASA Earth & Space Science Certificate Program for Pre-service Secondary Teachers (Invited)

    NASA Astrophysics Data System (ADS)

    Morrow, C. A.; Martin-Hansen, L.; Diem, J.; Elliott, W.

    2009-12-01

    An Atlanta-based partnership made up of leaders in science, education, and Georgia’s state-wide STEM Education Initiative are creating an enduring legacy of climate science education for pre-service and in-service teachers in Georgia as well as for underrepresented high school students who participate in an "Early College" program with Georgia State University (GSU). The core elements of our NASA-funded program are to infuse NASA global climate change resources and best pedagogical practice into a popular 4-credit lecture/lab course called “Introduction to Weather & Climate” (GEOG 1112) at GSU, and to establish a sustainable academic program for pre-service teachers in the College of Education called the NASA Earth & Space Science (ESS) Teacher Certificate. The NASA ESS Certificate will require candidates to accomplish the following as part of (or in addition to) standard degree and licensure requirements: 1. successfully complete a graduate section of “Introduction to Weather and Climate” (GEOG 7112), which requires lesson planning related to course content and engagement with GSU's new CO2 monitoring station whose research-quality data will provide unique hands-on opportunities for Metro Atlanta students and teachers; 2) complete an additional advanced course in climate change (GEOG 6784) plus elective hours in physical science disciplines (e.g. astronomy and physics); 3) serve as a lab teaching assistant for GEOG 1112 and a coach for a cadre of Carver Early College students who are taking the course; 4) make at least one of two teaching practica at a Georgia-based NASA Explorer School; and 5) participate or co-present in a week-long, residential, field-based, Summer Institute in Earth & Space Science intended to increase the interest, knowledge, and ability of in-service secondary science educators to fulfill climate-related standards in Earth Science and Earth Systems Science. We will evaluate, document, and disseminate (to the University System of

  8. Removal of Phosphorus in Metallurgical Silicon by Rare Earth Elements

    NASA Astrophysics Data System (ADS)

    Tang, Kai; Løvvik, Ole Martin; Safarian, Jafar; Ma, Xiang; Tangstad, Merete

    2014-09-01

    Removal of phosphorus in metallurgical silicon is one of the crucial steps for the production of solar grade Si feedstock. The possibility of doping rare earth elements for phosphorus removal has in this work been studied both theoretically and experimentally. Thermochemical properties of Ce, Nd, and Pr monophosphides have first been estimated by ab initio thermodynamic simulations based on density functional theory and the direct phonon method. The reliability of the first principles calculations was assessed by coupling with the phase diagram data of the Pr-P system. Equilibrium calculations confirmed the existence of stable rare earth monophosphides in solid silicon. Experimental investigations were then carried out, employing a high temperature resistance furnace. The Ce-doped silicon samples were examined by electron probe micro analyzer and inductively coupled plasma analysis. The efficiency of phosphorus removal by means of rare earth doping was discussed in detail in the paper.

  9. Earth observing system: 1989 reference handbook

    NASA Technical Reports Server (NTRS)

    1989-01-01

    NASA is studying a coordinated effort called the Mission to Planet Earth to understand global change. The goals are to understand the Earth as a system, and to determine those processes that contribute to the environmental balance, as well as those that may result in changes. The Earth Observing System (Eos) is the centerpiece of the program. Eos will create an integrated scientific observing system that will enable multidisciplinary study of the Earth including the atmosphere, oceans, land surface, polar regions, and solid Earth. Science goals, the Eos data and information system, experiments, measuring instruments, and interdisciplinary investigations are described.

  10. Discover Earth: Earth's Energy Budget or Can You Spare a Sun?

    NASA Technical Reports Server (NTRS)

    Gates, Tom; Peters, Dale E.; Steeley, Jeanne

    1999-01-01

    Discover Earth is a NASA-sponsored project for teachers of grades 5-12, designed to: enhance understanding of the Earth as an integrated system enhance the interdisciplinary approach to science instruction, and provide classroom materials that focus on those goals. Discover Earth is conducted by the Institute for Global Environmental Strategies in collaboration with Dr. Eric Barron, Director, Earth System Science Center, The Pennsylvania State University; and Dr. Robert Hudson, Chair, the Department of Meteorology, University of Maryland at College Park.

  11. Lead-free epitaxial ferroelectric material integration on semiconducting (100) Nb-doped SrTiO3 for low-power non-volatile memory and efficient ultraviolet ray detection

    NASA Astrophysics Data System (ADS)

    Kundu, Souvik; Clavel, Michael; Biswas, Pranab; Chen, Bo; Song, Hyun-Cheol; Kumar, Prashant; Halder, Nripendra N.; Hudait, Mantu K.; Banerji, Pallab; Sanghadasa, Mohan; Priya, Shashank

    2015-07-01

    We report lead-free ferroelectric based resistive switching non-volatile memory (NVM) devices with epitaxial (1-x)BaTiO3-xBiFeO3 (x = 0.725) (BT-BFO) film integrated on semiconducting (100) Nb (0.7%) doped SrTiO3 (Nb:STO) substrates. The piezoelectric force microscopy (PFM) measurement at room temperature demonstrated ferroelectricity in the BT-BFO thin film. PFM results also reveal the repeatable polarization inversion by poling, manifesting its potential for read-write operation in NVM devices. The electroforming-free and ferroelectric polarization coupled electrical behaviour demonstrated excellent resistive switching with high retention time, cyclic endurance, and low set/reset voltages. X-ray photoelectron spectroscopy was utilized to determine the band alignment at the BT-BFO and Nb:STO heterojunction, and it exhibited staggered band alignment. This heterojunction is found to behave as an efficient ultraviolet photo-detector with low rise and fall time. The architecture also demonstrates half-wave rectification under low and high input signal frequencies, where the output distortion is minimal. The results provide avenue for an electrical switch that can regulate the pixels in low or high frequency images. Combined this work paves the pathway towards designing future generation low-power ferroelectric based microelectronic devices by merging both electrical and photovoltaic properties of BT-BFO materials.

  12. Lead-free epitaxial ferroelectric material integration on semiconducting (100) Nb-doped SrTiO3 for low-power non-volatile memory and efficient ultraviolet ray detection.

    PubMed

    Kundu, Souvik; Clavel, Michael; Biswas, Pranab; Chen, Bo; Song, Hyun-Cheol; Kumar, Prashant; Halder, Nripendra N; Hudait, Mantu K; Banerji, Pallab; Sanghadasa, Mohan; Priya, Shashank

    2015-01-01

    We report lead-free ferroelectric based resistive switching non-volatile memory (NVM) devices with epitaxial (1-x)BaTiO3-xBiFeO3 (x = 0.725) (BT-BFO) film integrated on semiconducting (100) Nb (0.7%) doped SrTiO3 (Nb:STO) substrates. The piezoelectric force microscopy (PFM) measurement at room temperature demonstrated ferroelectricity in the BT-BFO thin film. PFM results also reveal the repeatable polarization inversion by poling, manifesting its potential for read-write operation in NVM devices. The electroforming-free and ferroelectric polarization coupled electrical behaviour demonstrated excellent resistive switching with high retention time, cyclic endurance, and low set/reset voltages. X-ray photoelectron spectroscopy was utilized to determine the band alignment at the BT-BFO and Nb:STO heterojunction, and it exhibited staggered band alignment. This heterojunction is found to behave as an efficient ultraviolet photo-detector with low rise and fall time. The architecture also demonstrates half-wave rectification under low and high input signal frequencies, where the output distortion is minimal. The results provide avenue for an electrical switch that can regulate the pixels in low or high frequency images. Combined this work paves the pathway towards designing future generation low-power ferroelectric based microelectronic devices by merging both electrical and photovoltaic properties of BT-BFO materials.

  13. Hybrid quantum nanophotonic devices for coupling to rare-earth ions

    NASA Astrophysics Data System (ADS)

    Miyazono, Evan; Hartz, Alex; Zhong, Tian; Faraon, Andrei

    2015-03-01

    With an assortment of narrow line-width transitions spanning the visible and IR spectrum and long spin coherence times, rare-earth doped crystals are the leading material system for solid-state quantum memories. Integrating these materials in an on-chip optical platform would create opportunities for highly integrated light-matter interfaces for quantum communication and quantum computing. Nano-photonic resonators with high quality factors and small mode volumes are required for efficient on-chip coupling to the small dipole moment of rare-earth ion transitions. However, direct fabrication of optical cavities in these crystals with current nanofabrication techniques is difficult and unparallelized, as either exotic etch chemistries or physical milling processes are required. We fabricated hybrid devices by mechanically transferring a nanoscale membrane of gallium arsenide (GaAs) onto a neodymium-doped yttrium silicon oxide (Y2SiO5) crystal and then using electron beam lithography and standard III-V dry etching to pattern nanobeam photonic crystal cavities and ring resonator cavities, a technique that is easily adapted to other frequency ranges for arbitrary dopants in any rare earth host system. Single crystalline GaAs was chosen for its low loss and high refractive index at the transition wavelength. We demonstrated the potential to evanescently couple between the cavity field and the 883 nm 4I9/2- 4F3/2 transition of nearby neodymium impurities in the host crystal by examining transmission spectra through a waveguide coupled to the resonator with a custom-built confocal microscope. The prospects and requirements for using this system for scalable quantum networks are discussed.

  14. Computer modelling of the reduction of rare earth dopants in barium aluminate

    SciTech Connect

    Rezende, Marcos V. dos S; Valerio, Mario E.G.; Jackson, Robert A.

    2011-08-15

    Long lasting phosphorescence in barium aluminates can be achieved by doping with rare earth ions in divalent charge states. The rare earth ions are initially in a trivalent charge state, but are reduced to a divalent charge state before being doped into the material. In this paper, the reduction of trivalent rare earth ions in the BaAl{sub 2}O{sub 4} lattice is studied by computer simulation, with the energetics of the whole reduction and doping process being modelled by two methods, one based on single ion doping and one which allows dopant concentrations to be taken into account. A range of different reduction schemes are considered and the most energetically favourable schemes identified. - Graphical abstract: The doping and subsequent reduction of a rare earth ion into the barium aluminate lattice. Highlights: > The doping of barium aluminate with rare earth ions reduced in a range of atmospheres has been modelled. > The overall solution energy for the doping process for each ion in each reducing atmosphere is calculated using two methods. > The lowest energy reduction process is predicted and compared with experimental results.

  15. The Effects of Student Multiple Intelligence Preference on Integration of Earth Science Concepts and Knowledge within a Middle Grades Science Classroom.

    ERIC Educational Resources Information Center

    Cutshall, Lisa Christine

    This research was conducted in an eastern Tennessee 8th grade science classroom with 99 students participating. The action research project attempted to examine an adolescent science student's integration of science concepts within a project-based setting using the multiple intelligence theory. In an effort to address the national science…

  16. NASA's Current Earth Science Program

    NASA Technical Reports Server (NTRS)

    Charles, Leslie Bermann

    1998-01-01

    NASA's Earth science program is a scientific endeavor whose goal is to provide long-term understanding of the Earth as an integrated system of land, water, air and life. A highly developed scientific knowledge of the Earth system is necessary to understand how the environment affects humanity, and how humanity may be affecting the environment. The remote sensing technologies used to gather the global environmental data used in such research also have numerous practical applications. Current applications of remote sensing data demonstrate their practical benefits in areas such as the monitoring of crop conditions and yields, natural disasters and forest fires; hazardous waste clean up; and tracking of vector-borne diseases. The long-term availability of environmental data is essential for the continuity of important research and applications efforts. NASA's Earth observation program has undergone many changes in the recent past.

  17. Classroom Earth!

    ERIC Educational Resources Information Center

    Horton, Tom

    1999-01-01

    Educators are rediscovering the benefits of using the local natural environment as an integrating context (EIC) for curriculum. Once called "nature study," this form of hands-on environmental education draws on the connectedness inherent in natural systems to forge meaningful links in student learning. Sidebars describe EIC projects at three…

  18. The Anti-Doping Movement.

    PubMed

    Willick, Stuart E; Miller, Geoffrey D; Eichner, Daniel

    2016-03-01

    Historical reports of doping in sports date as far back as the ancient Greek Olympic Games. The anti-doping community considers doping in sports to be cheating and a violation of the spirit of sport. During the past century, there has been an increasing awareness of the extent of doping in sports and the health risks of doping. In response, the anti-doping movement has endeavored to educate athletes and others about the health risks of doping and promote a level playing field. Doping control is now undertaken in most countries around the world and at most elite sports competitions. As athletes have found new ways to dope, however, the anti-doping community has endeavored to strengthen its educational and deterrence efforts. It is incumbent upon sports medicine professionals to understand the health risks of doping and all doping control processes. PMID:26972261

  19. The Anti-Doping Movement.

    PubMed

    Willick, Stuart E; Miller, Geoffrey D; Eichner, Daniel

    2016-03-01

    Historical reports of doping in sports date as far back as the ancient Greek Olympic Games. The anti-doping community considers doping in sports to be cheating and a violation of the spirit of sport. During the past century, there has been an increasing awareness of the extent of doping in sports and the health risks of doping. In response, the anti-doping movement has endeavored to educate athletes and others about the health risks of doping and promote a level playing field. Doping control is now undertaken in most countries around the world and at most elite sports competitions. As athletes have found new ways to dope, however, the anti-doping community has endeavored to strengthen its educational and deterrence efforts. It is incumbent upon sports medicine professionals to understand the health risks of doping and all doping control processes.

  20. The Earth Observing System

    NASA Technical Reports Server (NTRS)

    Shaffer, Lisa Robock

    1992-01-01

    The restructuring of the NASA Earth Observing System (EOS), designed to provide comprehensive long term observations from space of changes occurring on the Earth from natural and human causes in order to have a sound scientific basis for policy decisions on protection of the future, is reported. In response to several factors, the original program approved in the fiscal year 1991 budget was restructured and somewhat reduced in scope. The resulting program uses three different sized launch vehicles to put six different spacecraft in orbit in the first phase, followed by two replacement launches for each of five of the six satellites to maintain a long term observing capability to meet the needs of global climate change research and other science objectives. The EOS system, including the space observatories, the data and information system, and the interdisciplinary global change research effort, are approved and proceeding. Elements of EOS are already in place, such as the research investigations and initial data system capabilities. The flights of precursor satellite and Shuttle missions, the ongoing data analysis, and the evolutionary enhancements to the integrated Earth science data management capabilities are all important building blocks to the full EOS program.