Sample records for earth doped integrated

  1. Lateral color integration on rare-earth-doped GaN electroluminescent D. S. Lee and A. J. Steckla)

    E-print Network

    Steckl, Andrew J.

    -doped GaN has led to the successful fabrication of electrolumines- cent devices ELD with pure green,2Lateral color integration on rare-earth-doped GaN electroluminescent thin films D. S. Lee and A. J GaN thin films doped with Er and Eu. These rare-earth doped GaN GaN:RE films were grown on Si 111

  2. Rare-earth doped transparent nano-glass-ceramics: a new generation of photonic integrated devices

    NASA Astrophysics Data System (ADS)

    Rodríguez-Armas, Vicente Daniel; Tikhomirov, Victor K.; Méndez-Ramos, Jorge; Yanes, Angel C.; Del-Castillo, Javier; Furniss, David; Seddon, Angela B.

    2007-05-01

    We report on optical properties and prospect applications on rare-earth doped oxyfluoride precursor glass and ensuing nano-glass-ceramics. We find out the spectral optical gain of the nano-glass-ceramics and show that its flatness and breadth are advantageous as compared to contemporary used erbium doped optical amplifiers. We present the possibility of flat gain cross-section erbium doped waveguide amplifiers as short 'chip', all-optical, devices capable of dense wavelength division multiplexing, including the potential for direct writing of these devices inside bulk glasses for three-dimensional photonic integration. We carried out a comparative study of the up-conversion luminescence in Er 3+-doped and Yb 3+-Er 3+-Tm 3+ co-doped samples, which indicates that these materials can be used as green/red tuneable up-conversion phosphors and white light simulation respectively. Observed changes in the spectra of the up-conversion luminescence provide a tool for tuning the colour opening the way for producing 3-dimensional optical recording.

  3. Modeling and fabrication of rare-earth-doped integrated optical waveguide amplifiers

    NASA Astrophysics Data System (ADS)

    Krishnaswamy, Madhu

    This thesis addresses modeling and fabrication issues related to erbium/ytterbium-doped glass waveguide amplifiers. Compact optical waveguides which amplify light in the 1.55 ?m wavelength window will play an important role in complementing other integrated optic devices such as modulators and switches. In designing waveguide amplifiers, two features are of utmost importance: (1) high signal gain over short distances. (2) compatibility for integration with other devices. The requirement for gain over a short distance necessitates the use of rare-earth dopant levels two orders of magnitude higher than currently employed in fiber amplifiers. A numerical model to simulate the gain and noise characteristics of waveguide amplifiers doped heavily with rare-earth ions is described. Deleterious effects associated with high doping, such as ion-ion interaction, are included in the model. The model is validated by comparing simulation results with experimental and numerical results found in the literature. Based on modeling results, an attempt was made to fabricate compact ridge waveguides from thin films of sputter- deposited erbium-doped glass. In response to various spectroscopic and micromachining impediments encountered with this process, alternative waveguide configurations were explored. The design and fabrication of strip-loaded waveguides using two dielectric glass films in conjunction is discussed. In this configuration, micromachining impediments inherent to the active glass film can be circumvented. Experimental and simulation results for this device are shown to be in close agreement. Improvements are forecast by the model. Optical waveguides were also formed directly on rare- earth-doped bulk glasses. In one approach, a passive polymer waveguide was dispensed on top of a bulk glass. The evanescent field of light propagating in the polymer layer was seen to penetrate the bulk substrate and interact with rare-earth ions. Experimental and simulation results associated with this novel approach are discussed. Finally, an Er/Yb-doped optical waveguide amplifier yielding 3.5 dB of net signal gain over 4.2 cm with 120 mW of pump power is demonstrated. This singlemode device was formed on a bulk glass using a field-assisted, silver-sodium ion-exchange process.

  4. SYNTHESIS & INTEGRATION Earth Stewardship

    E-print Network

    Jackson, Robert B.

    SYNTHESIS & INTEGRATION Earth Stewardship: science for action to sustain the human-earth system F, A. G. Power, and A. Bartuska. 2011. Earth Stewardship: science for action to sustain the human-earth system. Ecosphere 2(8):art89. doi:10.1890/ES11-00166.1 Abstract. Human activities affect Earth's life

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

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...false Complex strontium aluminate, rare earth doped (generic). 721.10423 Section...10423 Complex strontium aluminate, rare earth doped (generic). (a) Chemical substances...generically as complex strontium aluminate, rare earth doped (PMNs P-12-22,...

  6. Tunable, rare earth-doped solid state lasers

    DOEpatents

    Emmett, John L. (Pleasanton, CA); Jacobs, Ralph R. (Livermore, CA); Krupke, William F. (Pleasanton, CA); Weber, Marvin J. (Danville, CA)

    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.

  7. Review of rare earth doped fibre lasers and amplifiers

    Microsoft Academic Search

    Paul Urquhart

    1988-01-01

    Recent developments in rare earth-doped fiber lasers and amplifiers are reviewed. Fiber lasers have been made to operate at a variety of wavelengths, including the important 1.3, 1.55, and 2 to 3 micron regions in the infrared. The spectra of the rare earth ions and the nature of the host materials that make such lasing wavelengths possible are discussed. Methods

  8. Study of rare-earth-doped scintillators

    NASA Astrophysics Data System (ADS)

    Yanagida, Takayuki

    2013-09-01

    Scintillators are widely used in radiation detection applications in basic science and industry. Scintillators are generally solids and consist of an emission center and a host lattice. Especially in medical applications that detect high-energy photons, the emission centers are rare-earth (RE) ions, mostly Ce3+. However, recently Pr3+ also exhibited fast 5d-4f emission and became an alternative to Ce3+. In X-ray computed tomography, a scintillation decay time on the order of microseconds is acceptable, and other rare-earth ions such as Nd3+, Eu2+, Ho3+, Er3+, and Tm3+ are candidates for the emission center. The characteristics of these inorganic materials and their advantages and disadvantages for scintillators will be discussed.

  9. Magnetic property improvement of niobium doped with rare earth elements

    NASA Astrophysics Data System (ADS)

    Jiang, Tao; He, Fei-Si; Jiao, Fei; He, Fa; Lu, Xiang-Yang; Zhao, Kui; Zhao, Hong-Yun; You, Yu-Song; Chen, Lin

    2014-05-01

    A new idea is proposed by the PKU group to improve the magnetic properties of the Type-II superconductor niobium. Rare earth elements like scandium and yttrium are doped into ingot niobium during the smelting processes. A series of experiments have been done since 2010. The preliminary testing results show that the magnetic properties of niobium materials have changed with different doping elements and proportions while the superconductive transition temperature does not change very much. This method may increase the superheating magnetic field of niobium so as to improve the performance of the niobium cavity, which is a key component of SRF accelerators. A Tesla-type single-cell cavity made of scandium-doped niobium is being fabricated.

  10. 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.

  11. Phase transition of nanostructure zirconias doped with rare earth elements.

    PubMed

    Li, Yan; Liu, Yang; Huang, Ling; Li, Xingguo

    2005-09-01

    Nanostructure zirconias doped with rare earth elements were obtained by coprecipitation. The morphology, structure, and phase transition of the as-prepared samples were studied. According to transmission electron microscopy, the particles appear in near spherical shape and have a mean particle sizes of about 150 nm without change with the rare earth elements. From laser Raman and X-ray diffraction results, it is known that the tetragonal phase of zirconia is stabilized by a certain concentration of the rare earth dopants, and the cubic phase is obtained if enough dopants are added. The crystal lattice increases with the increase of dopant concentration. Moreover, the heavy rare earths are better than the light ones in stabilizing effect. According to our study, laser Raman is more sensitive than X-ray diffraction in monitoring the phase transition. PMID:16193972

  12. 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 (?) 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 (?eff) 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.

  13. 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.

  14. Rare earth doped zinc oxide varistors

    DOEpatents

    McMillan, April D. (Knoxville, TN); Modine, Frank A. (Oak Ridge, TN); Lauf, Robert J. (Oak Ridge, TN); Alim, Mohammad A. (Medina, OH); Mahan, Gerald D. (Oak Ridge, TN); Bartkowiak, Miroslaw (Oak Ridge, TN)

    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.

  15. Preparation and up-conversion luminescence of 8 nm rare-earth doped fluoride nanoparticles

    E-print Network

    Moshchalkov, Victor V.

    Preparation and up-conversion luminescence of 8 nm rare-earth doped fluoride nanoparticles V.Tikhomirov@fys.kuleuven.be, Christiane.Walrand@chem.kuleuven.be Abstract: Free-standing, 8 nm diameter, rare-earth doped nanoparticles Re10Pb25F65 have been prepared, where Re stands for either single rare-earth ion, such as Er3+ , Yb3

  16. Optoelectronic properties of transition metal and rare earth doped epitaxial layers on InP for magneto-optics

    Microsoft Academic Search

    B. J. H. Stadler; K. Vaccaro; A. Davis; G. O. Ramseyer; E. A. Martin; H. M. Dauplaise; L. M. Theodore; J. P. Lorenzo

    1996-01-01

    Rare earth-and transition metal-doped thin films of InP, In0.53Ga0.47As, and In0.71Ga0.29As0.58P0.42 were grown by liquid phase epitaxy and evaluated for use in integrated electro-optical and magneto-optical applications,\\u000a such as waveguides and Faraday rotators. The films were lattice matched to (100) InP substrates, and the transition metal\\u000a (Mn) and rare earth (Gd, Eu, and Er) doping concentra-tions were between 2.6 ×

  17. Optoelectronic properties of transition metal and rare earth doped epitaxial layers on InP for magneto-optics

    Microsoft Academic Search

    B. J. H. Stadler; K. Vaccaro; A. Davis; G. O. Ramseyer; E. A. Martin; H. M. Dauplaise; L. M. Theodore; J. P. Lorenzo

    1996-01-01

    Rare earth-and transition metal-doped thin films of InP, In0.53Ga0.47As, and In0.71Ga0.29As0.58P0.42 were grown by liquid phase epitaxy and evaluated for use in integrated electro-optical and magneto-optical applications, such as waveguides and Faraday rotators. The films were lattice matched to (100) InP substrates, and the transition metal (Mn) and rare earth (Gd, Eu, and Er) doping concentra-tions were between 2.6 ×

  18. Rare earth doped III-nitrides for optoelectronics

    NASA Astrophysics Data System (ADS)

    O'Donnell, K. P.; Hourahine, B.

    2006-11-01

    Rare-earth (RE) doped III-nitrides, prepared by in-situ doping during growth or by ion implantation and annealing, are promising materials for visible light emitting displays. In addition, they are extremely challenging theoretically, on account of the complexity of the sharp inter-4f optical transitions, which are allowed only through the mixing by non-centrosymmetric crystal fields of the inner 4f orbitals with higher-lying states of opposite parity. We review recent experimental and theoretical work on Er-, Eu- and Tm-doped III-nitride compounds and alloys which has been carried out with a view to establishing the lattice location of RE in these materials and the probable nanostructure of the centres which are responsible for their luminescence. The isolated site REIII is found to be both optically and electrically inactive, but in association with neighbouring intrinsic defects (most probably nitrogen vacancies) REIII can generate a small family of similar optically active sites. Such a family is held to be responsible for the site multiplicity that is a common feature of the spectroscopy of RE-doped III-nitrides.

  19. Rare earth doped upconverting particles for different photonic applications

    NASA Astrophysics Data System (ADS)

    Pokhrel, Madhab; Gangadharan, Ajith Kumar; Sardar, Dhiraj Kumar

    2013-03-01

    Trivalent rare earth ions especially erbium (Er^3+) and ytterbium (Yb^3+) co-doped in various host nanoparticles are known for their extraordinary spectroscopic properties. A thorough optical characterization including the absolute upconversion quantum yield (QY) measurement is of critical importance in evaluating their potential for various photonic applications. In this paper, we will be presenting a measured absolute upconversion QYs for Yb^3+ and Er^3+ doped in La2O2S under 980 and 1550 nm excitation at various power densities. Comparison of absolute QYs for different concentrations of Yb^3+ and Er^3+ doped in La2O2S will be made for all the upconversion emissions with respect to reported most efficient upconverting phosphor NaYF4 doped with 20% Yb^3+ and 2% Er^3+. Furthermore, applications of these phosphors in different areas such as bio-imaging, solar cell, security, etc. will be explored depending on the measured absolute upconversion quantum yields. In addition, preliminary results on in vitro imaging using upconverting nanoparticles as a contrast agent will be reported.

  20. Magnetoreactance Studies in Rare Earth-Doped Ni Ferrite

    Microsoft Academic Search

    Sandhya Dwevedi; K. Kamala Bharathi; G. Markandeyulu

    2009-01-01

    Structural, electrical, and magnetoreactance (mr) characteristics of rare earth-doped Ni ferrite (NiO.Fe2-xRxO3 (x = 0, 0.075, R = Dy, Gd) , and NiO.Fe1.95R0.05O3 (R = Gd, Nd)) were investigated. All the materials formed in the cubic inverse spinel phase with small amounts of RFeO3 as the additional phase. mr was measured in both longitudinal and transverse configuration. A mr of

  1. 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.

  2. VISIBLE AND INFRARED RARE-EARTH ACTIVATED ELECTROLUMINESCENCE FROM ERBIUM DOPED GaN

    E-print Network

    Steckl, Andrew J.

    characteristics of Er-doped GaN LEDs emitting in both the visible and IR regions. EXPERIMENT The GaN:Er lightVISIBLE AND INFRARED RARE-EARTH ACTIVATED ELECTROLUMINESCENCE FROM ERBIUM DOPED GaN M. Garter*, R temperature visible and IR light electroluminescence (EL) has been obtained from Er-doped GaN Schottky barrier

  3. 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.

  4. 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.

  5. Thermopower studies of rare earth doped lanthanum barium manganites

    NASA Astrophysics Data System (ADS)

    Reddy, G. Lalitha; Lakshmi, Y. Kalyana; kumar, N. Pavan; Rao, S. Manjunath; Reddy, P. Venugopal

    2014-08-01

    Influence of rare earth doping on electrical, magnetic and thermopower studies of La0.34Re0.33Ba0.33MnO3 compound was investigated. Ferro to paramagnetic transition and metal to insulator transition temperatures decrease with decreasing ionic radius of the dopant ion. Electrical resistivity in the entire temperature range is explained by phase separation model. The magnitude of Seebeck coefficient increases with increasing dopant ionic radius. A cross over from negative to positive sign has also been observed in thermopower data with decreasing A site ionic radius (). The low temperature thermopower data has been explained using a qualitative model containing diffusion; magnon drag and phonon drag effects while the paramagnetic insulating part has been analyzed using small polaron hopping mechanism.

  6. 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.

  7. Pressure studies of alkali, alkaline earth and rare earth doped C{sub 60} superconductors

    SciTech Connect

    Schirber, J.E.; Bayless, W.R. [Sandia National Labs., Albuquerque, NM (United States); Kortan, A.R.; Ozdas, E.; Zhou, O.; Murphy, D. [AT and T Bell Labs., Murray Hill, NJ (United States); Fischer, J.E. [Pennsylvania Univ., Philadelphia, PA (United States)

    1994-06-01

    Pressure studies of the superconducting transition temperature T{sub c} of the alkali metal doped C{sub 60} compounds helped to establish a universal curve of T{sub c} versus lattice constant upon which nearly all of these materials lie. Various theoretical schemes incorporate this finding and suggest that only the lattice parameter and not the details of the dopant determine T{sub c}. Ca{sub 5}C{sub 60}, the highest T{sub c} member of the alkaline earth doped C{sub 60} superconductor has a T{sub c} which lies on this universal curve so this material, from these considerations, should have the same large negative pressure derivative as the alkali doped superconductors. We have measured dT{sub c}/dP for Ca{sub 5}C{sub 60} and for Yb{sub x}C{sub 60} (x near 3) and find small and positive values indicating that the theoretical models must be expanded to include band structure effects.

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

    SciTech Connect

    Adijanto, Lawrence, E-mail: adijanto@seas.upenn.edu [Department of Chemical and Biomolecular Engineering, 220 South 33rd Street 311A Towne Building, University of Pennsylvania Philadelphia, PA 19104-6315 (United States); Balaji Padmanabhan, Venu, E-mail: venub@seas.upenn.edu [Department of Chemical and Biomolecular Engineering, 220 South 33rd Street 311A Towne Building, University of Pennsylvania Philadelphia, PA 19104-6315 (United States); Holmes, Kevin J., E-mail: kholmes@seas.upenn.edu [Department of Chemical and Biomolecular Engineering, 220 South 33rd Street 311A Towne Building, University of Pennsylvania Philadelphia, PA 19104-6315 (United States); Gorte, Raymond J., E-mail: gorte@seas.upenn.edu [Department of Chemical and Biomolecular Engineering, 220 South 33rd Street 311A Towne Building, University of Pennsylvania Philadelphia, PA 19104-6315 (United States); Vohs, John M., E-mail: vohs@seas.upenn.edu [Department of Chemical and Biomolecular Engineering, 220 South 33rd Street 311A Towne Building, University of Pennsylvania Philadelphia, PA 19104-6315 (United States)

    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.

  9. Synthesized rare-earth doped oxide glasses for nonlinear optics

    NASA Astrophysics Data System (ADS)

    Kityk, I. V.; Wasylak, J.; Benet, S.; Dorosz, D.; Kucharski, J.; Krasowski, J.; Sahraoui, B.

    2002-09-01

    Photostimulated nonlinear optical effects in synthesized PbO-Ga2O3-Bi2O3-CdO (PGBC) glasses doped by Yb3+, Er3+, and Dy3+ rare-earth (RE3+) ions were discovered. Temperature-dependent measurements of optical photoinduced second-harmonic generation (PISHG) and two-photon absorption were performed in the infrared (IR) range. CO pulse laser (lambda=5.5 mum, energy power density up to 3.8 GW/cm2 per pulse) was applied as a source of IR-photoinducing and probing (fundamental) light. Absolute values of the PISHG were more than 22% higher than corresponding values obtained for other glasses: As2Te3-CaCl2-PbCl2 1 or Sb2Se3-BaCl2-PbCl2 2 type. The investigated PGBC system possesses a shorter time response (about 18 ps), compared with other IR nonlinear optical glasses. We have also established that all nonlinear optical susceptibilities are dependent on the type of RE3+ ion. A maximal value of the PISHG is achieved for the glasses doped by Yb3+. The PISHG values increase significantly below 25 K. We have carried out ab initio molecular dynamics and quantum chemical simulations in order to evaluate the possible contribution of electron-phonon anharmonic interactions in the observed phenomena. We have modeled the influence of the external CO photoinduced beam through the photoinduced anharmonic electron-phonon interactions. A decrease of the delaying time response is achieved. To obtain independent confirmation of the observed dependencies, we have carried out measurements of the epsilon2)(E during the external IR pumping. We have also compared the measured and theoretically calculated dependencies of the IR-induced effects.

  10. Engineering broadband and anisotropic photoluminescence emission from rare earth doped tellurite thin film photonic crystals

    E-print Network

    Vanhoutte, Michiel

    Broadband and anisotropic light emission from rare-earth doped tellurite thin films is demonstrated using Er[superscript 3+]-TeO[subscript 2] photonic crystals (PhCs). By adjusting the PhC parameters, photoluminescent light ...

  11. Integrated Instrument Simulator Suites for Earth Science

    NASA Technical Reports Server (NTRS)

    Tanelli, Simone; Tao, Wei-Kuo; Matsui, Toshihisa; Hostetler, Chris; Hair, John; 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.

  12. 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

  13. Magnetic-field effect on the phonon echoes in a rare-earth-doped glass F. Lerbet and G. Bellessa

    E-print Network

    Boyer, Edmond

    1251 Magnetic-field effect on the phonon echoes in a rare-earth-doped glass F. Lerbet and G field increases from 0 to 60 kOe. Relaxation of the tunnelling states by the rare-earth ions.50K Photon echoes in a rare-earth-doped glass have shown that the optical dephasing rates are enhanced

  14. DIPOLE ORIENTATION EFFECTS IN RARE-EARTH DOPED CdF, R. CAPELLETTI, F. FERMI and E. OKUNO (*)

    E-print Network

    Boyer, Edmond

    DIPOLE ORIENTATION EFFECTS IN RARE-EARTH DOPED CdF, R. CAPELLETTI, F. FERMI and E. OKUNO (*) Gruppo in the tempera- ture range 80-200 K shows ~~nequivocallythat n. 11. Rare Earth-Fluorine Interstitial (RE known that rare earth doped CaF, shows two well delined 1TC peaks [8], [9] due to orientation of RE

  15. Towards atomic scale engineering of rare-earth-doped SiAlON ceramics through aberration-corrected scanning transmission

    E-print Network

    Pennycook, Steve

    Towards atomic scale engineering of rare-earth-doped SiAlON ceramics through aberration visualization of rare earths in a- and b-SiAlON unit-cells is performed through Z-contrast imaging technique kinds of rare-earth-doped materials. Ã? 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights

  16. Water-soluble conjugated polyelectrolyte brush encapsulated rare-earth ion doped nanoparticles with dual-upconversion properties for multicolor cell imaging.

    PubMed

    Hu, Wenbo; Lu, Xiaomei; Jiang, Rongcui; Fan, Quli; Zhao, Hui; Deng, Weixing; Zhang, Lei; Huang, Ling; Huang, Wei

    2013-10-11

    A concise route to prepare water-soluble rare-earth ion doped upconversion nanoparticles (UCNPs) by encapsulation of grafted cationic conjugated polyelectrolyte brushes (PFNBr) is reported. Integrating two kinds of upconversion materials effectively addresses multicolor fluorescence by introducing the concept of dual-upconversion. PMID:23969491

  17. Surface characterization of sol-gel derived scintillating rare-earth doped Lu2SiO5 thin films

    E-print Network

    Paris-Sud XI, Université de

    Surface characterization of sol-gel derived scintillating rare- earth doped Lu2SiO5 thin films C-marie.nedelec@univ-bpclermont.fr Abstract. Rare earth doped Lu2SiO5 thin films have been prepared by combining sol-gel process and spin of rare earth doping ions. XPS and RBS spectrocopies showed that the composition of the films is close

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

    SciTech Connect

    Nayek, C.; Thirmal, Ch.; Murugavel, P., E-mail: muruga@iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 36 (India); Tamilselvan, A.; Balakumar, S. [National Centre for Nanoscience and Nanotechnology, University of Madras, Chennai 25 (India)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    We report structural and magnetic properties of rare earth doped Bi0.95R0.05 FeO3 (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 R3Fe5O12 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 BiFeO3 compounds along with the structural distortion favoring spin canting by increase in Dzyaloshinskii-Moriya exchange energy.

  20. Upconversion-pumped luminescence efficiency of rare-earth-doped hosts sensitized with trivalent ytterbium

    SciTech Connect

    Page, R.H.; Schaffers, K.I.; Waide, P.A.; Tassano, J.B.; Payne, S.A.; Kruplce, W.F.; Bischel, W.K. [Gemfire Corporation, Palo Alto, CA (United States)

    1997-07-26

    We discuss the upconversion luminescence efficiencies of phosphors that generate red, green, and blue light. The phosphors studied are single crystals and powders co-doped with Er{sup 3+} and Yb{sup 3+}, and with Tm{sup 3+} and Yb{sup 3+}. The Yb ions are pumped near 980 nm; transfers of two or three quanta to the co-doped rare earth ion generate visible luminescence. The main contribution embodied in this work is the quantitative measurement of this upconversion efficiency, based on the use of a calibrated integrating sphere, determination of the fraction of pump light absorbed, and careful control of the pump laser beam profile. The green phosphors are the most efficient, yielding efficiency values as high as 4 %, with the red and blue materials giving 1 - 2 %. Saturation was observed in all cases, suggesting that populations of upconversion steps of the ions are maximized at higher power. Quasi-CW modeling of the intensity- dependent upconversion efficiency was attempted; input data included level lifetimes, transition cross sections, and cross-relaxation rate coefficients. The saturation of the Yb,Er:fluoride media is explained as the pumping of Er{sup 3+} ions into a bottleneck (long-lived state)- the {sup 4}I{sub 13/2} metastable level, making them unavailable for further excitation transfer. 32 refs., 5 figs., 3 tabs.

  1. Earth’s Nearest Neighbors: Dynamical integrations of NEO-Earth approaches in support of MANOS

    NASA Astrophysics Data System (ADS)

    Endicott, Thomas; Moskovitz, Nicholas; Binzel, Richard; Polishook, David; Burt, Brian

    2014-11-01

    The Mission Accessible Near-Earth Object Survey (MANOS) began in August 2013 as a multi-year physical characterization survey that was awarded large survey status by NOAO. MANOS will target several hundred mission-accessible NEOs across visible and near-infrared wavelengths, ultimately providing a comprehensive catalog of physical properties (astrometry, light curves, spectra). In support of this telescopic survey, we are performing a suite of orbital integrations to investigate the dynamical evolution of the near-Earth asteroid population.Using orbital information from the Lowell Observatory AstOrb database and the swift orbital integration package, we compute the orbital history of every known NEO from present day to five hundred thousand years in the past. This orbital history is used to identify the temporal evolution of each NEO's minimum orbital intersection distance (MOID) value, quantifying the physical distance between the orbits of a given NEO and that of a terrestrial planet. Due to the non-deterministic behavior of many NEO orbits beyond a few hundred years, these integrated MOIDs do not uniquely determine whether an NEO and a planet will actually encounter one another, bur rather provide a probabilistic metric for the proximity in which two objects can encounter one another. Integrated MOIDs can be a useful tool for correlating measured physical properties with high probabilities of planetary encounters (e.g. Binzel et al. 2010, Nature 463, 331).We will present the status of these orbital integrations. These integrations show a variety of dynamical histories, from objects that are stable over the integration limits to those that show chaotic behavior after approximately fifty to one hundred thousand years. These orbital integrations are being used to track the potentially hazardous object (PHA) population over time, to evaluate dynamical history for both specific objects and NEO sub-populations, and to estimate the evolution of NEO surface temperatures due to changing perihelion distances.

  2. Structure and properties of soda lime silicate glass doped with rare earth

    NASA Astrophysics Data System (ADS)

    Wang, Mi-tang; Cheng, Jin-shu; Li, Mei; He, Feng

    2011-01-01

    Soda-lime-silicate glasses doped with different rare-earth oxides (La 2O 3, CeO 2, Nd 2O 3, Gd 2O 3 and Y 2O 3) of 1 mol% content were prepared with the traditional melting-quenching methods. In order to reveal the effects of rare-earth elements on the behavior of soda-lime-silicate glass, the structure of soda-lime-silicate glasses doped with different rare-earth oxides were determined with Fourier transform infrared spectrometer using the KBr method, and viscosity of glass melts were measured by the rotating crucible viscometer, the melting temperature of the studied glasses were derived on the basis of Arrhenius Equation, moreover the density, bending strength and molar volume were measured and calculated. The effect of rare-earth dopants on the structure of soda-lime-silicate was analyzed by a shift of peak position and variation in the full-width at half-maximum. The effect of doping rare-earth oxides into glass on the viscosity, density and bending strength was interpreted by changing in structure of soda-lime-silicate glasses doped with rare-earth oxides.

  3. 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.

  4. Fluorescence Spectroscopy of Polymer Systems Doped with Rare-Earth Metal Ions and Their Complexes

    Microsoft Academic Search

    K. S. V. Krishna Rao; Hong-Guo Liu; Yong-Ill Lee

    2010-01-01

    There has been an increased attention to explore the possibility of using polymer materials with rare-earth (RE) metal ions and their complexes as potential optical materials due to their capability of exhibiting novel and unusual properties. The fluorescence characteristics of polymer systems doped with RE metal ions and\\/or their complexes were analyzed and the effects of the doping metal ion\\/metal

  5. Multiferroism in rare earth metals-doped BiFeO3 nanowires

    NASA Astrophysics Data System (ADS)

    Lotey, Gurmeet Singh; Verma, N. K.

    2013-08-01

    Nanowires are the key multifunctional materials for the development towards device miniaturization and high-density data storage systems for future nanoelectronics. In the present report, multifunctional undoped and rare earth metals ions (Gd3+, Tb3+, Dy3+)-doped BiFeO3 nanowires with 20 nm diameter, have been synthesized by template-assisted colloidal dispersion technique. The effect of the size of synthesized nanowires, as well as, the doping of rare earth ions on the structural, magnetic, dielectric and magnetodielectric properties have been studied. The doping of rare earth metals ions leads to structural transition from rhombohedral to orthorhombic BiFeO3 nanowires. The synthesized nanowires exhibit ferromagnetic nature with high value of saturation magnetization, dielectric constant and magnetodielectric coefficient.

  6. Supplementary Information: The Grid ENabled Integrated Earth system modelling (GENIE)

    E-print Network

    Edwards, Neil

    Supplementary Information: The Grid ENabled Integrated Earth system modelling (GENIE) framework T Integrated Earth system modelling (GENIE) frame- work supports modularity (i.e. interchangeable components the GENIE framework. The components, models, and their notation are summarized in Table 1. As a rule, we

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

    SciTech Connect

    Liu, J., E-mail: liujjx@sdu.edu.cn; Wang, C. L.; Li, Y.; Su, W. B.; Zhu, Y. H.; Li, J. C.; Mei, L. M. [School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China)

    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)

  8. Integrating Live Access Server into Google Earth

    NASA Astrophysics Data System (ADS)

    Li, J.; Schweitzer, R.; Hankin, S.; O'Brien, K.

    2006-12-01

    The Live Access Server (LAS) is a highly configurable Web server designed to provide flexible access to visualization and analysis products generated from geo-referenced scientific data sets. Now at version 7.0, LAS has been in operation since 1994. The current ~{!0~}Armstrong?release of LAS V7 consists of a set of modular components in a three tiered architecture -- user interface, workflow orchestration and services to access data and generate scientific products. The LAS user interface (UI) helps the user make requests, preventing requests that are impossible or unreasonable. The UI communicates with the LAS Product Server (LPS the workflow orchestration component) via an XML string with an HTTP GET. When a request is received by the LPS, business logic converts this request into a series of Web Service requests invoked via SOAP. The SOAP services perform data access and generate products (visualizations, data subsets, analyses, etc.). LPS packages these outputs into final products via Jakarta Velocity templates for delivery to the end user. Back-end services are most often a legacy application wrapped in a Java class. The Java wrapper classes are deployed as Web Services accessible via SOAP using the AxisServlet and a custom Web Services Deployment Descriptor file. Ferret is the default visualization application used by LAS, though other applications (e.g. Matlab, CDAT, and GrADS) can also be used. This application demonstrates how Keyhole Markup Language (KML) can be used to provide simple integration of LAS and Google Earth. KML makes access to "Virtual Globe" capabilities so simple that it can be added as an option to existing systems. This application is one such example. The ability to package an image in KML was added to the LAS as a new SOAP service. On the LAS user interface, users can select a Google Earth product in the same manner that any other LAS product is requested. The server will dynamically generate a KML file, which contains the 2D plot requested by the user. Then, the plot can be viewed in the Google Earth desktop application.

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

    E-print Network

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

    2013-01-01

    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) are achieved by tuning either the dipolar or quadrupolar particle resonance to the rare earth ions 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.

  10. Interfacing superconducting qubits and telecom photons via a rare-earth-doped crystal.

    PubMed

    O'Brien, Christopher; Lauk, Nikolai; Blum, Susanne; Morigi, Giovanna; Fleischhauer, Michael

    2014-08-01

    We propose a scheme to couple short single photon pulses to superconducting qubits. An optical photon is first absorbed into an inhomogeneously broadened rare-earth doped crystal using controlled reversible inhomogeneous broadening. The optical excitation is then mapped into a spin state using a series of ? pulses and subsequently transferred to a superconducting qubit via a microwave cavity. To overcome the intrinsic and engineered inhomogeneous broadening of the optical and spin transitions in rare-earth doped crystals, we make use of a special transfer protocol using staggered ? pulses. We predict total transfer efficiencies on the order of 90%. PMID:25148328

  11. Interfacing Superconducting Qubits and Telecom Photons via a Rare-Earth-Doped Crystal

    NASA Astrophysics Data System (ADS)

    O'Brien, Christopher; Lauk, Nikolai; Blum, Susanne; Morigi, Giovanna; Fleischhauer, Michael

    2014-08-01

    We propose a scheme to couple short single photon pulses to superconducting qubits. An optical photon is first absorbed into an inhomogeneously broadened rare-earth doped crystal using controlled reversible inhomogeneous broadening. The optical excitation is then mapped into a spin state using a series of ? pulses and subsequently transferred to a superconducting qubit via a microwave cavity. To overcome the intrinsic and engineered inhomogeneous broadening of the optical and spin transitions in rare-earth doped crystals, we make use of a special transfer protocol using staggered ? pulses. We predict total transfer efficiencies on the order of 90%.

  12. 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. PMID:24231223

  13. Interfacing Superconducting Qubits and Telecom Photons via a Rare-Earth Doped Crystal

    E-print Network

    Christopher O'Brien; Nikolai Lauk; Susanne Blum; Giovanna Morigi; Michael Fleischhauer

    2014-07-25

    We propose a scheme to couple short single photon pulses to superconducting qubits. An optical photon is first absorbed into an inhomogeneously broadened rare-earth doped crystal using controlled reversible inhomogeneous broadening. The optical excitation is then mapped into a spin state using a series of $\\pi$-pulses and subsequently transferred to a superconducting qubit via a microwave cavity. To overcome the intrinsic and engineered inhomogeneous broadening of the optical and spin transitions in rare earth doped crystals, we make use of a special transfer protocol using staggered $\\pi$-pulses. We predict total transfer efficiencies on the order of 90%.

  14. UV and gamma-ray excited luminescence of cerium-doped rare-earth oxyorthosilicates

    Microsoft Academic Search

    H. Suzuki; T. A. Tombrello; C. L. Melcher; J. S. Schweitzer

    1992-01-01

    Gamma-ray and UV-excitation of cerium-doped rare-earth oxyorthosilicates (RE = Y, Gd, and Lu) has been used to investigate the emission mechanism for this family of scintillators. The data clearly indicate the presence of two different luminescence centers, which are attributed to cerium substitution in the two different rare-earth crystallographic sites. While this model explains much of the present and previous

  15. Scintillation of Sol-Gel derived Lutetium orthophosphate doped with rare earth ions.

    E-print Network

    Paris-Sud XI, Université de

    1 Scintillation of Sol-Gel derived Lutetium orthophosphate doped with rare earth ions. C. Mansuy1. Because of the required high density, lutetium based oxides materials are very interesting candidates Section Materials preparation Sol-Gel derived samples In a first step, a mixture of Lutetium and Ln

  16. Research of green emitting rare-earth doped materials as potential quantum-cutter

    Microsoft Academic Search

    Bernard Moine; Lena Beauzamy; Patrick Gredin; Gilles Wallez; Jessica Labeguerie

    2008-01-01

    Because the energy of vacuum ultraviolet (VUV) photons emitted by xenon plasma discharge is more than twice that of visible photons, quantum cutting appears to be a promising process in rare-earth doped materials in order to obtain efficient phosphors for mercury free lighting devices as well as for plasma display panels. With an aim of application, it is important to

  17. Quantum computer hardware based on rare-earth-ion-doped inorganic crystals

    Microsoft Academic Search

    Nicklas Ohlsson; R Krishna Mohan; Stefan Kröll

    2002-01-01

    We present a scheme for generating multiple, strongly interacting qubits in rare-earth-ion-doped inorganic crystals at cryogenic temperatures. Two ground state hyperfine levels, with hour long lifetimes and ms decoherence times are chosen as qubit states. Controlled logic between the qubits is accomplished using the change in permanent dipole moment induced by an optical transition between the ground and excited state

  18. Optical and structural investigation on rare-earth-doped aluminophosphate glasses

    NASA Astrophysics Data System (ADS)

    Elisa, M.; Cristina Vasiliu, I.; Grigorescu, Cristiana E. A.; Grigoras, Bogdan; Niciu, Horatiu; Niciu, Daniela; Meghea, Aurelia; Iftimie, Nicoleta; Giurginca, Maria; Trodahl, H. J.; Dalley, M.

    2006-05-01

    Aluminophosphate glasses belonging to the oxide system Li 2O-BaO-Al 2O 3-La 2O 3-P 2O 5, un-doped and doped with rare-earth metal ions (Ce 4+, Nd 3+, Sm 3+) were obtained by a wet non-conventional method. The influence of the doping ions on the optical properties of the phosphate glasses has been investigated in relation with structural features of the vitreous matrix. The optical behavior has been studied by ultra-violet-visible-near-infra-red (UV-VIS-NIR) spectroscopy, revealing electronic transitions specific for rare-earth ions. Structural information via optical phonons was provided by infrared (IR) absorption spectra in the range 400-4000 cm -1. Raman and fluorescence spectroscopy measurements have been performed. A strong fluorescence was observed in the visible spectrum, using 514.5 nm and 633 nm laser excitation.

  19. Crystal-field study in rare-earth-doped semiconducting YBiPt P. G. Pagliuso and C. Rettori

    E-print Network

    Martins, George

    Crystal-field study in rare-earth-doped semiconducting YBiPt P. G. Pagliuso and C. Rettori-susceptibility experiments in the rare-earth-doped (R Nd, Er, and Yb cubic semiconducting YBiPt allow estimates of the fourth was observed. S0163-1829 99 10925-1 I. INTRODUCTION The series of intermetallic compounds RBiPt (R rare earths

  20. Luminescent dye-doped or rare-earth-doped monodisperse silica nanospheres as efficient labels in DNA microarrays

    NASA Astrophysics Data System (ADS)

    Enrichi, F.; Riccò, R.; Meneghello, A.; Pierobon, R.; Marinello, F.; Schiavuta, P.

    2009-08-01

    Luminescent nanoparticles are gaining more and more interest in bio-labeling and bio-imaging applications, like for example DNA microarray. This is a high-throughput technology used for detection and quantification of nucleic acid molecules and other ones of biological interest. The analysis is resulting by specific hybridization between probe sequences deposited in array and a target ss-DNA usually expressed by PCR and functionalized by a fluorescent dye. These organic labels have well known disadvantages like photobleaching and limited sensitivity. Quantum dots may be used as alternatives, but they present troubles like blinking, toxicity and excitation wavelengths out of the usual range of commercial instruments, lowering their efficiency. Therefore in this work we investigate a different strategy, based on the use of inorganic silica nanospheres incorporating standard luminescent dyes or rare earth doped nanocrystals. In the first case it is possible to obtain a high luminescence emission signal, due to the high number of dye molecules that can be accommodated into each nanoparticle, reduced photobleaching and environmental protection of the dye molecules thanks to the encapsulation in the silica matrix. In the second case, rare earths exhibit narrow emission bands (easy identification), large Stokes shifts (efficient discrimination of excitation and emission) and long luminescence lifetimes (possibility to perform time-delayed analysis) which can be efficiently used for the improvement of signal to noise ratio. The synthesis and characterization of good luminescent silica spheres either by organic dye-doping or by rare-earth-doping are investigated and reported. Moreover, their application in the DNA microarray technology in comparison to the use of standard molecular fluorophores or commercial quantum dots is discussed. The cheap and easy synthesis of these luminescent particles, the stability in water, the surface functionalization and bio-compatibility makes them very promising for present and future applications in bio-labeling and bio-imaging.

  1. EC-EARTH: an Earth System Model based on the ECWMF Integrated Forecasting System

    Microsoft Academic Search

    F. Selten; R. Bintanja; S. Yang; C. Severijns; T. Semmler; K. Wyser; X. Wang; W. Hazeleger

    2009-01-01

    EC-EARTH is the name of an Earth system model that is being developed by a number of institutes in Europe. It is based on the Integrated Forecast System of the European Centre for Medium Range Weather Forecasts (ECWMF). The ECMWF model delivers the best weather forecasts in the world by an objective measure. However, when applied to climate time scales,

  2. Digital Earth system based river basin data integration

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Li, Wanqing; Lin, Chao

    2014-12-01

    Digital Earth is an integrated approach to build scientific infrastructure. The Digital Earth systems provide a three-dimensional visualization and integration platform for river basin data which include the management data, in situ observation data, remote sensing observation data and model output data. This paper studies the Digital Earth system based river basin data integration technology. Firstly, the construction of the Digital Earth based three-dimensional river basin data integration environment is discussed. Then the river basin management data integration technology is presented which is realized by general database access interface, web service and ActiveX control. Thirdly, the in situ data stored in database tables as records integration is realized with three-dimensional model of the corresponding observation apparatus display in the Digital Earth system by a same ID code. In the next two parts, the remote sensing data and the model output data integration technologies are discussed in detail. The application in the Digital Zhang River basin System of China shows that the method can effectively improve the using efficiency and visualization effect of the data.

  3. Integrating Customized Geographical Data Into Google Earth 

    E-print Network

    Hu, Chenwei

    2011-11-24

    to download these files and then visualize their data in Google Earth. Various languages and programmes were used in this project, including Oracle RDBMS, SQL, Perl, HTML and KML. The Web-based tool provides users with limited GIS knowledge the ability to use...

  4. Modification of phonon processes in nano-structured rare-earth-ion-doped crystals

    E-print Network

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

    2015-04-09

    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 optical 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 certain approaches to optical quantum memories. We specifically discuss how phonon engineering can enable spectral hole burning in erbium-doped materials operating in the telecommunication band, and present simulations for density of states of nano-sized powders and phononic crystals for the case of Y$_2$SiO$_5$, a widely-used material in current quantum memory research.

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

    E-print Network

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

    2015-01-01

    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 optical 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 certain approaches to optical quantum memories. We specifically discuss how phonon engineering can enable spectral hole burning in erbium-doped materials operating in the telecommunication band, and present simulations for density of states of nano-sized powders and phononic crystals for the case of Y$_2$SiO$_5$, a widely-used material in current quantum memory research.

  6. Investigation of luminescent dye-doped or rare-earth-doped monodisperse silica nanospheres for DNA microarray labelling

    NASA Astrophysics Data System (ADS)

    Enrichi, F.; Riccò, R.; Meneghello, A.; Pierobon, R.; Cretaio, E.; Marinello, F.; Schiavuta, P.; Parma, A.; Riello, P.; Benedetti, A.

    2010-10-01

    DNA microarray is a high-throughput technology used for detection and quantification of nucleic acid molecules and others of biological interest. The analysis is resulting by specific hybridization between probe sequences deposited in array and a target ss-DNA usually functionalized by a luminescent dye. These organic labels have well known disadvantages like photobleaching and limited sensitivity. Therefore in this work we investigate a different strategy, based on the use of inorganic silica nanospheres incorporating standard luminescent dyes or rare earth ions. The synthesis and characterization of these biomarkers is reported and their application to the DNA microarray technology in comparison to the use of standard molecular fluorophores or commercial quantum dots is discussed. We show that dye doped silica spheres provides a significant increase of the optical emission signal with respect to the use of free dyes, while rare earth doped silica spheres allow reducing or completely avoiding the background noise. These aspects, together with their cheap and easy synthesis, stability in water, easy surface functionalization and bio-compatibility makes them very promising for present and future applications in bio-labelling and bio-imaging.

  7. 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. PMID:20828167

  8. Materials Science and Engineering B81 (2001) 97101 Multiple color capability from rare earth-doped gallium nitride

    E-print Network

    Steckl, Andrew J.

    of Cincinnati, Cincinnati, OH 45221-0030, USA Abstract Rare earth (RE) doping of GaN has led to a new full color thin film electroluminescent (TFEL) phosphor system. GaN films doped with Eu, Er, and Tm dopants emit pure red, green, and blue emission colors, respectively. As a host for RE luminescent centers, GaN

  9. Integrated computational materials discovery of silver doped tin sulfide as a thermoelectric material.

    PubMed

    Bera, Chandan; Jacob, Stephane; Opahle, Ingo; Gunda, N S Harsha; Chmielowski, Radoslaw; Dennler, Gilles; Madsen, Georg K H

    2014-10-01

    Accelerating the discovery of new materials is crucial for realizing the vision of need-driven materials development. In the present study we employ an integrated computational and experimental approach to search for new thermoelectric materials. High-throughput first principles calculations of thermoelectric transport coefficients are used to screen sulfide compounds conforming to the boundary conditions of abundant and innocuous components. A further computational screening step of substitutional defects is introduced, whereby SnS doped with monovalent cations is identified as having favorable transport properties. By silver doping of SnS under S-rich conditions an electric conductivity more than an order of magnitude higher than reported previously is realized. The obtained thermoelectric power-factor at room temperature is comparable to the state of the art for thermoelectric materials based on earth abundant, non-toxic elements. The high-throughput screening of extrinsic defects solves a long standing bottleneck in search of new thermoelectric materials. We show how the intrinsic carrier concentration in the low-temperature phase of SnSe is two orders of magnitude higher than in SnS. We furthermore find that the carrier concentration in SnSe can still be further optimized by silver doping. PMID:25115284

  10. Using the earth system for integrating the science curriculum

    NASA Astrophysics Data System (ADS)

    Mayer, Victor J.

    Content and process instruction from the earth sciences has gone unrepresented in the world's science curricula, especially at the secondary level. As a result there is a serious deficiency in public understanding of the planet on which we all live. This lack includes national and international leaders in politics, business, and science. The earth system science effort now engaging the research talent of the earth sciences provides a firm foundation from the sciences for inclusion of earth systems content into the evolving integrated science curricula of this country and others. Implementing integrated science curricula, especially at the secondary level where potential leaders often have their only exposure to science, can help to address these problems. The earth system provides a conceptual theme as opposed to a disciplinary theme for organizing such integrated curricula, absent from prior efforts. The end of the cold war era is resulting in a reexamination of science and the influence it has had on our planet and society. In the future, science and the curricula that teach about science must seriously address the environmental and social problems left in the wake of over 100 years of preparation for military and economic war. The earth systems education effort provides one such approach to the modernization of science curricula. Earth science educators should assume leadership in helping to establish such curricula in this country and around the world.

  11. Ab initio Disordered Local Moment Approach for a Doped Rare-Earth Magnet

    NASA Astrophysics Data System (ADS)

    Matsumoto, Munehisa; Banerjee, Rudra; Staunton, Julie B.

    Following the finite-temperature ab initio calculation framework based on the relativistic disordered local moments [J. B. Staunton et al., Phys. Rev. Lett. 93, 257204 (2004); Phys. Rev. B 74, 144411 (2006)], we computationally demonstrate the possibility of doping-enhanced coercivity at high-temperatures, taking YCo5 as a working material in order to extract the 3d-electron part of the electronic structure of the rare-earth permanent magnets. Alkaline-earth dopants are shown to be the candidates to realize the proposed phenomenon.

  12. Enhanced blue and green emission in rare-earth-doped GaN electroluminescent devices by optical photopumping

    E-print Network

    Steckl, Andrew J.

    as well as mixed colors by RE codoping.14 GaN films were grown on p-type 111 Si substrates by molecularEnhanced blue and green emission in rare-earth-doped GaN electroluminescent devices by optical from rare-earth-doped GaN GaN:RE EL devices ELD emission has been observed to be greatly enhanced

  13. Rare-earth-doped GVO films grown by pulsed laser deposition

    Microsoft Academic Search

    S. Bär; H. Scheife; G. Huber

    2006-01-01

    Bulk crystals of the vanadates YVO4 and GdVO4 are well-known hosts for lanthanide ions and have been widely used in solid-state lasers as well as in phosphors. We report on the thin film growth of rare-earth-doped GdVO4 by pulsed laser deposition. These films were grown either nearly homoepitaxially on YVO4-substrates or heteroepitaxially on ?-Al2O3-substrates. The first spectroscopic results of an

  14. A highly photoactive bilayer lipid membrane doped with a rare-earth complex

    Microsoft Academic Search

    Yi-Jin Xiao; Xiao-Xia Gao; Chun-Hui Huang; Ke-Zhi Wang

    1994-01-01

    A novel photosensitizer composed of a hemicyanine cation and a rare-earth complex anion (PLnL[sub 4]) was doped into bilayer lipid membranes (BLM) to produce a large photocurrent. The highest photocurrent across the PYbL[sub 4]-BLM may reach to about 50nA under continuous illumination by visible light. It was found that the great enhancement of the photoresponse is due to the promotion

  15. Analytical model for rare-earth-doped fiber amplifiers and lasers

    Microsoft Academic Search

    C. Barnard; P. Myslinski; J. Chrostowski; M. Kavehrad

    1994-01-01

    An analytical model for two-, three-, and four-level system rare-earth-doped fiber amplifiers and lasers is presented. The theory is applicable to dopants such as erbium, neodymium, thulium; praseodymium, and ytterbium. Fiber-amplifier gain is expressed in terms of attenuation coefficients, intrinsic saturation powers, and cross-saturation powers at the pump and signal wavelengths. These parameters can be directly determined from one- and

  16. Integrated Earth Systems: Confronting Global Change

    NSDL National Science Digital Library

    Ellen Mosley-Thompson

    This site is the course syllabus for a geography course taught at Ohio State University. The course is designed to provide a basic understanding of both natural and human caused climate change. Lectures explore the issues surrounding recent climate change and the role of human activities in shaping the physical, chemical and biological characteristics of the environment that sustains life on Earth. Links to the class homepage, tutorials and quizzes from the textbook, and a list of course topics are also included.

  17. Research of green emitting rare-earth doped materials as potential quantum-cutter

    NASA Astrophysics Data System (ADS)

    Moine, Bernard; Beauzamy, Lena; Gredin, Patrick; Wallez, Gilles; Labeguerie, Jessica

    2008-03-01

    Because the energy of vacuum ultraviolet (VUV) photons emitted by xenon plasma discharge is more than twice that of visible photons, quantum cutting appears to be a promising process in rare-earth doped materials in order to obtain efficient phosphors for mercury free lighting devices as well as for plasma display panels. With an aim of application, it is important to take into account the emitting color of the developed new phosphors. Most of the time, this leads to use systems with at least two kinds of rare earth ions: one of them playing the role of energy sensitizer, and the other one being in charge of emitting the light of the suitable color. We focus our attention on green rare-earth doped materials. In order to get very efficient phosphors, it is not only necessary to get the highest possible quantum yield, but also to have a material characterized by a strong absorption in the VUV range. Borate and fluoride matrices doped with Dy 3+/Tb 3+ couples of ions are selected according to the position of the 5d band of dysprosium as green emitters.

  18. Microemulsion synthesis, characterization of highly visible light responsive rare earth-doped Bi2O3.

    PubMed

    Wu, Shuxing; Fang, Jianzhang; Xu, Xiaoxin; Liu, Zhang; Zhu, Ximiao; Xu, Weicheng

    2012-01-01

    In this paper, Bi(2)O(3) and rare earth (La, Ce)-doped Bi(2)O(3) visible-light-driven photocatalysts were prepared in a Triton X-100/n-hexanol/cyclohexane/water reverse microemulsion. The resulting materials were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area, photoluminescence spectra (PLS) and UV-Vis diffuse reflectance spectroscopy. The XRD patterns of the as-prepared catalysts calcined at 500 °C exhibited only the characteristic peaks of monoclinic ?-Bi(2)O(3). PLS analysis implied that the separation efficiency for electron-hole has been enhanced when Bi(2)O(3) was doped with rare earth. UV-Vis diffuse reflectance spectroscopy measurements presented an extension of light absorption into the visible region. The photocatalytic activity of the samples was evaluated by degradation of methyl orange (MO) and 2,4-dichlorophenol (2,4-DCP). The results displayed that the photocatalytic activity of rare earth-doped Bi(2)O(3) was higher than that of dopant-free Bi(2)O(3). The optimal dopant amount of La or Ce was 1.0 mol%. And the mechanisms of influence on the photocatalytic activity of the catalysts were discussed. PMID:22530926

  19. Rare-earth-doped photonic crystals for the development of solid-state optical cryocoolers

    NASA Astrophysics Data System (ADS)

    Garcia-Adeva, Angel J.; Balda, Rolindes; Fernández, Joaquín

    2009-02-01

    Optical cryocoolers made of luminescent solids are very promising for many applications in the fields of optical telecommunications, aerospace industry, bioimaging, and phototherapy. To the present day, researchers have employed a number of crystal and glass host materials doped with rare-earth ions (Yb3+, Tm3+, and Er3+) to yield anti-Stokes optical refrigeration. In these host materials, the attainable minimum temperature is limited by the average phonon energy of the lattice and the impurity concentration. However, recently Ruan and Kaviany have theoretically demonstrated that the cooling efficiency can be dramatically enhanced when the host material doped with rare-earth ions is ground into a powder made of sub-micron size grains. This is due to two facts: firstly, the phonon spectrum is modified due to finite size of the grains and, secondly, light localization effects increase the photon density, leading to an enhanced absorptivity. In the present work, we propose that using a photonic crystal doped with rare earth ions offers many advantages with regards to getting a larger cooling efficiency at room temperature when compared to standard bulk materials or nano-powders. Indeed, apart to analogous phenomena to the ones predicted in nano-crystalline powders, there is the possibility of directly controlling the spontaneous emission rate of the ions embedded in the structure and, also, the absorption rate in the Stokes side of the absorption band by adequately tuning the density of photonic states, thus obtaining a large improvement in the cooling efficiency.

  20. Structural and magnetic property of Mn:ZnO bulk ceramic doped with rare earth (Gd/Sm) atoms

    NASA Astrophysics Data System (ADS)

    Das, J.; Mishra, D. K.; Sahu, D. R.; Roul, B. K.

    2012-09-01

    This paper reports the paramagnetic behavior of Mn doped ZnO co-doped with rare earth (Gd and Sm) atoms. The formation of secondary rare earth oxides (Gd2O3 and Sm2O3) is confirmed from the X-ray diffraction patterns. The rare earth oxides in the system forbids the grain growth and interconnection between the grains. The weak link between the grains suppresses the long range exchange interaction between the Mn ions and hence, reduces the ferromagnetic ordering. Owing to the large mismatch between ionic radii of rare earth and transition metal atoms inside the matrix, the rare earth element cannot contribute to promote ferromagnetic behavior in Mn doped ZnO, irrespective of their high individual magnetic moments.

  1. Sputter deposition of rare earth doped zinc sulfide for near infrared electroluminescence

    NASA Astrophysics Data System (ADS)

    Glass, William Robert, III

    2003-10-01

    Near infrared emitting alternating current thin film electroluminescent (ACTFEL) phosphors were fabricated by simultaneous R.F. magnetron sputtering from both a target of doped ZnS and an undoped ZnS target. The intensities of both near infrared (NIR) and visible emission from ZnS doped with thulium (Tm), neodymium (Nd), or erbium (Er) fluorides were dependent on deposition parameters such as target duty cycle (varied from 25 to 100% independently for the two targets) and substrate temperature (140--180°C), with lower temperatures giving 400% better NIR brightness. By optimizing the rare earth concentration between 0.8 and 1.1 at%, the near infrared irradiance was improved by 400% for each dopant. The increase in brightness and optimal concentrations are attributed to decreased crystallinity and increased dopant interaction at higher rare earth concentrations. The brightness increase with decreasing deposition temperature was attributed to a reduction of thermal desorption of the ZnS during deposition, and consequently thicker films and optimized rare earth concentration. Luminescent decay lifetimes were short (20--40 musec) because of a high concentration of non-radiative pathways due to defects from the strain of the large rare earth ions on the ZnS lattice. The threshold voltage for visible and near infrared emission was identical despite emission of NIR and visible light resulting from electrons relaxing from low and high energy excited levels, respectively. The optical threshold voltages were identical to the electrical threshold voltages, and it was concluded that at the voltages necessary for electrical breakdown, the accelerated electrons had enough energy to excite either the visible or NIR emitting levels. Phosphors doped with Nd exhibited increased internal charge at higher dopant concentrations despite a reduction in phosphor field (i.e. reduced applied voltage) In contrast; the charge did not change appreciably for Er and decreased for Tm doped films at reduced fields. The charge differences were attributed to dopant effects on the distribution of states near the interfaces. It was postulated that Nd doped devices have a shallower state distribution, while the majority of states in Tm doped devices are deeper and require higher fields for tunnel injection. The electrical behavior of all of the devices also demonstrated that field clamping occurred despite non-ideal phosphor breakdown during device operation. It is postulated that a high breakdown strength, low dielectric constant, interface layer is formed during deposition, and reduces capacitance before and after phosphor breakdown and results in field clamping. The thickness calculated for the interface layer decreases with increasing deposition temperature implying that the layer is formed during deposition, and this decreasing thickness results from increased atomic mobility at higher temperatures.

  2. Novel online security system based on rare-earth-doped glass microbeads

    NASA Astrophysics Data System (ADS)

    Officer, Simon; Prabhu, G. R.; Pollard, Pat; Hunter, Catherine; Ross, Gary A.

    2004-06-01

    A novel fluorescent security label has been produced that could replace numerous conventional fluorescent dyes in document security. This label utilizes rare earth ions doped in a borosilicate glass matrix to produce sharp spectral fluorescence peaks with characteristic long lifetimes due to the rare earth ions. These are subsequently detected by an online detection system based on fluorescence and the long lifetimes to avoid any interference from other fluorophores present in the background. Security is further enhanced by the interaction of the rare earth ions with each other and the effect of the host on the emission spectra and therefore the number of permutations that could be produced. This creates a very secure label with various applications for the security market.

  3. Luminescence properties of rare earth and transition metal ions doped potassium lead borophosphate glass

    NASA Astrophysics Data System (ADS)

    Leong, P. M.; Eeu, T. Y.; Leow, T. Q.; Hussin, R.; Ibrahim, Z.

    2013-05-01

    A series of potassium lead borophosphate glass doped with rare earth and transition metal ions were fabricated using melt-quenching method without annealing process. With the composition of glass 0.15K2O-0.15PbO-0.35B2O3-0.5P2O5 as host doped with 0.01 mole % of neodymium oxide, iron oxide, yttrium oxide, and titanium oxide as activator and different composition were used to investigate the luminescence effect by using Photoluminescence Spectroscopy and UV-Vis (Ultraviolet-Visible) spectrophotometer. By exciting the samples at different wavelength (200-900 nm), the excitation and emission profile were obtained and analyzed to study the energy transfer process. By referring to the spectra obtained, selected samples were also codoped among each other to obtain desired luminescence properties. UV-Visible spectroscopy results revealed the absorption and transmission wavelength of samples for targeted application as a selected band filter. Physical properties such as chemical stability and color of the samples were also recorded to correlate with PL and UV-Vis result. Certain rare earth activated samples displayed slight coloring under the visible wavelength especially Nd2+ ions doped samples displayed slight purplish.

  4. 28th European Photovoltaic Solar Energy Conference and Exhibition 1.BO11.2 DOWN CONVERTER DEVICE COMBINING RARE-EARTH DOPED THIN LAYER AND PHOTONIC

    E-print Network

    Paris-Sud XI, Université de

    COMBINING RARE-EARTH DOPED THIN LAYER AND PHOTONIC CRYSTAL FOR C-SI BASED SOLAR CELL Thierry Deschamps1 structure combines rare-earths doped thin layer allowing the down-conversion process with a photonic crystal of the rare-earths doped layer, a silicon nitride (SiN) 2D planar PhC is synthesized. For that, SiN is first

  5. Multi-color fluorescence in rare earth acetylacetonate hydrate doped poly methyl methacrylate

    NASA Astrophysics Data System (ADS)

    Zhang, Y. Y.; Shen, L. F.; Pun, E. Y. B.; Chen, B. J.; Lin, H.

    2013-01-01

    Europium and terbium acetylacetonate hydrates were doped into poly methyl methacrylate (PMMA). Efficient purplish-red and green fluorescence was obtained from europium acetylacetonate hydrates (EAH) and terbium acetylacetonate hydrates (TAH) doped PMMA respectively. Judd-Ofelt parameters ?2 (19.73×10-20 cm2) and ?4 (2.19×10-20 cm2) indicate a high inversion asymmetric and strong covalent environment in PMMA. The maximum stimulated emission cross-sections for the 5D0?7FJ (J=1, 2 and 4) transitions in EAH doped PMMA were calculated to be 0.38×10-21, 4.90×10-21 and 0.36×10-21 cm2, respectively. Variable fluorescence color can be efficiently achieved from the cooperation of three fluorescence colors offered by red (Eu3+), green (Tb3+) and blue (ligand) in EAH/TAH codoped PMMA by adjusting the excitation wavelength. These results indicate that PMMA is an effective photoluminescence co-sensitizer and PMMA doped with rare earth acetylacetonate hydrates is a promising candidate for a series of optoelectronic functional devices.

  6. Design of rare-earth-ion doped chalcogenide photonic crystals for enhancing the fluorescence emission

    NASA Astrophysics Data System (ADS)

    Zhang, Peiqing; Dai, Shixun; Niu, Xueke; Xu, Yinsheng; Zhang, Wei; Wu, Yuehao; Xu, Tiefeng; Nie, Qiuhua

    2014-07-01

    Rare-earth-ion doped chalcogenide glass is a promising material for developing mid-infrared light sources. In this work, Tm3+-doped chalcogenide glass was prepared and photonic crystal structures were designed to enhance its fluorescence emission at approximately 3.8 ?m. By employing the finite-difference time-domain (FDTD) simulation, the emission characteristics of the luminescent centers in the bulk material and in the photonic crystals were worked out. Utilizing analysis of the photon excitation inside the sample and the photon extraction on the sample surface, it was found that fluorescence emission can be significantly enhanced 260-fold with the designed photonic crystal structure. The results of this work can be used to realize high-efficiency mid-infrared light sources.

  7. 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.

  8. Crystallization studies on rare-earth co-doped fluorozirconate-based glasses

    PubMed Central

    Paßlick, C.; Johnson, J.A.; Schweizer, S.

    2013-01-01

    This work focuses on the structural changes of barium chloride (BaCl2) nanoparticles in fluorochlorozirconate-based glass ceramics when doped with two different luminescent activators, in this case rare-earth (RE) ions, and thermally processed using a differential scanning calorimeter. In a first step, only europium in its divalent and trivalent oxidation states, Eu2+ and Eu3+, is investigated, which shows no significant influence on the crystallization of hexagonal phase BaCl2. However, higher amounts of Eu2+ increase the activation energy of the phase transition to an orthorhombic crystal structure. In a second step, nucleation and nanocrystal growth are influenced by changing the structural environment of the glasses by co-doping with Eu2+ and trivalent Gd3+, Nd3+, Yb3+, or Tb3+, due to the different atomic radii and electro-negativity of the co-dopants. PMID:23745010

  9. Luminescence Properties of Rare-Earth-Doped Thiosilicate Phosphors on Silicon Substrate

    NASA Astrophysics Data System (ADS)

    Nanai, Yasushi; Sakamoto, Yu; Okuno, Tsuyoshi

    2013-04-01

    The luminescence properties of rare-earth-doped thiosilicate phosphors are reported. These thiosilicate materials are fabricated in phosphor layers on silicon substrates. For Eu2+-doped calcium thiosilicate, yellow (560 nm) and red (650 nm) bands are obtained in the photoluminescence spectrum, which is almost the same as that for the corresponding powder sample. The energy transfer efficiency from Eu2+ to Er3+ in Eu2SiS4:Er3+ on Si substrates is improved by optimization of the annealing conditions. In addition, the insulation of electroluminescence devices using BaSi2S5:Eu2+ on silicon-on-insulator substrates is improved using a high-dielectric-constant polymer as a transparent insulating layer.

  10. Crystallization studies on rare-earth co-doped fluorozirconate-based glasses.

    PubMed

    Paßlick, C; Johnson, J A; Schweizer, S

    2013-07-01

    This work focuses on the structural changes of barium chloride (BaCl2) nanoparticles in fluorochlorozirconate-based glass ceramics when doped with two different luminescent activators, in this case rare-earth (RE) ions, and thermally processed using a differential scanning calorimeter. In a first step, only europium in its divalent and trivalent oxidation states, Eu(2+) and Eu(3+), is investigated, which shows no significant influence on the crystallization of hexagonal phase BaCl2. However, higher amounts of Eu(2+) increase the activation energy of the phase transition to an orthorhombic crystal structure. In a second step, nucleation and nanocrystal growth are influenced by changing the structural environment of the glasses by co-doping with Eu(2+) and trivalent Gd(3+), Nd(3+), Yb(3+), or Tb(3+), due to the different atomic radii and electro-negativity of the co-dopants. PMID:23745010

  11. Spectroscopic and electrical properties of Mg Ti ferrite doped with different rare-earth elements

    NASA Astrophysics Data System (ADS)

    Ahmed, M. A.; Ateia, E.; Salem, F. M.

    2006-05-01

    The dielectric constant ( ??), and the electric conductivity ( ?) for Mg 1+xTi xR yFe 2-2x-yO 4, 0.025? y?0.15 doped with different rare-earth ions, R=Er, Ce and Nd, were measured in the temperature range 300-750 K. The measurements were carried out as a function of frequency 50-1000 kHz X-ray diffractograms and IR spectra revealed that all the investigated samples posses the spinel structure. More than one conduction mechanism is used to interpret the electrical measurements. The most predominant one is the hopping mechanism that occurs between the ions of different valences existing on the same and different sites. All the ionic radii of the rare-earth used are too large to occupy the octahedral site. They form secondary phases on the grain boundaries. The electrical properties show that the pure sample has a larger dielectric constant as well as a larger valence exchange with respect to any doped one. This means that introducing rare-earth ions into the samples decreases ?? and increases the resistivity, owing to the decreasing Fe-Fe interaction. This feature can help to obtain well applicable ferrites.

  12. Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO? fiber.

    PubMed

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

    2014-08-01

    Visible light thermal radiation from SiO2 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 SiO2 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 SiO2 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 SiO2 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 SiO2 fibers are smaller than those from SiO2 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 SiO2 are potentially applicable for the fiber-optic thermometry above 900 K. PMID:25173299

  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 been used to study the micro-particles samples. Surface profilometery was used to study thin film samples. Characterization and material testing using high-resolution laser induced fluorescence spectroscopy and spectral holebuming are quite unique and necessary for the materials prepared in the present study. However, optical studies are beyond the scope of this project. Therefore, low temperature laser excited fluorescence and holebuming data has been presented to support the success of the fabricated thin films for spectral storage. Such studies are completely independent and self-contained investigations performed by other members of the group.

  14. Spectroscopic and electrical properties of Mg Ti ferrite doped with different rare-earth elements

    Microsoft Academic Search

    M. A. Ahmed; E. Ateia; F. M. Salem

    2006-01-01

    The dielectric constant (?'), and the electric conductivity (sigma) for Mg1+xTixRyFe2-2x-yO4, 0.025<=y<=0.15 doped with different rare-earth ions, R=Er, Ce and Nd, were measured in the temperature range 300 750 K. The measurements were carried out as a function of frequency 50 1000 kHz X-ray diffractograms and IR spectra revealed that all the investigated samples posses the spinel structure. More than

  15. Spectroscopic and electrical properties of Mg–Ti ferrite doped with different rare-earth elements

    Microsoft Academic Search

    M. A. Ahmed; E. Ateia; F. M. Salem

    2006-01-01

    The dielectric constant (??), and the electric conductivity (?) for Mg1+xTixRyFe2?2x?yO4, 0.025?y?0.15 doped with different rare-earth ions, R=Er, Ce and Nd, were measured in the temperature range 300–750K. The measurements were carried out as a function of frequency 50–1000kHz X-ray diffractograms and IR spectra revealed that all the investigated samples posses the spinel structure. More than one conduction mechanism is

  16. 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

  17. Initial experiments concerning quantum information processing in rare-earth-ion doped crystals

    E-print Network

    M. Nilsson; L. Levin; N. Ohlsson; T. Christiansson; S. Kroll

    2002-01-30

    In this paper initial experiments towards constructing simple quantum gates in a solid state material are presented. Instead of using specially tailored materials, the aim is to select a subset of randomly distributed ions in the material, which have the interaction necessary to control each other and therefore can be used to do quantum logic operations. The experimental results demonstrate that part of an inhomogeneously broadened absorption line can be selected as a qubit and that a subset of ions in the material can control the resonance frequency of other ions. This opens the way for the construction of quantum gates in rare-earth-ion doped crystals.

  18. Fibre tip sensors for localised temperature sensing based on rare earth-doped glass coatings.

    PubMed

    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

  19. Progress in rare-earth-doped mid-infrared fiber lasers.

    PubMed

    Seddon, Angela B; Tang, Zhuoqi; Furniss, David; Sujecki, Slawomir; Benson, Trevor M

    2010-12-01

    The progress, and current challenges, in fabricating rare-earth-doped chalcogenide-glass fibers for developing mid-infrared (IR) fiber lasers are reviewed. For the first time a coherent explanation is forwarded for the failure to date to develop a gallium-lanthanum-sulfide glass mid-IR fiber laser. For the more covalent chalcogenide glasses, the importance of optimizing the glass host and glass processing routes in order to minimize non-radiative decay and to avoid rare earth ion clustering and glass devitrification is discussed. For the first time a new idea is explored to explain an additional method of non-radiative depopulation of the excited state in the mid-IR that has not been properly recognized before: that of impurity multiphonon relaxation. Practical characterization of candidate selenide glasses is presented. Potential applications of mid-infrared fiber lasers are suggested. PMID:21165021

  20. Rare earth-doped nanocrystalline MgF2: Synthesis, luminescence and thermoluminescence

    NASA Astrophysics Data System (ADS)

    Jacobsohn, L. G.; Roy, A. L.; McPherson, C. L.; Kucera, C. J.; Oliveira, L. C.; Yukihara, E. G.; Ballato, J.

    2013-10-01

    The radioluminescence (RL) and thermoluminescence (TL) activation of MgF2 through the incorporation of rare earths is investigated in this work. These materials were obtained by ligand-free solution precipitation and calcination at 500 °C in air, and Ce, Eu and Tb were incorporated at the 1 mol% level. RL results of doped and undoped materials seem to indicate that the incorporation of rare earths creates effective luminescence centers, which is accompanied by an increase in the TL signal intensity in comparison with the undoped material. In particular, RL emission of MgF2:Ce is reported to be centered at 325 nm. The traps associated with the TL signal were found to be unstable under exposure to room light, suggesting potential for applications involving optically stimulated luminescence.

  1. 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, the B.S. in Integrated Earth Systems will serve those students who find excitement at the boundaries of these disciplines, and prepare them for careers in this emerging field. The ISS program will target high school students of the highest caliber who demonstrate strong aptitude in mathematics and the physical sciences, who will need a minimum amount of remedial work. These select students will be exposed to courses in Earth Systems: Cycles and Interactions, Geophysical Fluid Dynamics, Air-Sea Interaction, Boundary Layers and Turbulence, Climate Variability and Global Change, Atmosphere-Ocean Modeling, Solar-Terrestrial Interactions, Weather Systems Science, Earth Observing Systems, Remote Sensing and more, as part of the ISS curriculum. This paper will highlight the MU-DES programs and learning initiatives and expand and elaborate on the new program in ISS.

  2. The structure and energetics of $^3$He and $^4$He nanodroplets doped with alkaline earth atoms

    E-print Network

    A. Hernando; R. Mayol; M. Pi; M. Barranco; F. Ancilotto; O. B{ü}nermann; F. Stienkemeier

    2007-05-08

    We present systematic results, based on density functional calculations, for the structure and energetics of $^3$He and $^4$He nanodroplets doped with alkaline earth atoms. We predict that alkaline earth atoms from Mg to Ba go to the center of $^3$He drops, whereas Ca, Sr, and Ba reside in a deep dimple at the surface of $^4$He drops, and Mg is at their center. For Ca and Sr, the structure of the dimples is shown to be very sensitive to the He-alkaline earth pair potentials used in the calculations. The $5s5p\\leftarrow5s^2$ transition of strontium atoms attached to helium nanodroplets of either isotope has been probed in absorption experiments. The spectra show that strontium is solvated inside $^3$He nanodroplets, supporting the calculations. In the light of our findings, we emphasize the relevance of the heavier alkaline earth atoms for analyzing mixed $^3$He-$^4$He nanodroplets, and in particular, we suggest their use to experimentally probe the $^3$He-$^4$He interface.

  3. Catholuminescence properties of rare earth doped CaSnO3 phosphor.

    PubMed

    Canimoglu, A; Garcia-Guinea, J; Karabulut, Y; Ayvacikli, M; Jorge, A; Can, N

    2015-05-01

    The present study describes cathodoluminescence (CL) properties of CaSnO3 phosphors doped with Eu(3+), Tb(3+) and Dy(3+) synthesized by a solid-state method. X-ray diffraction (XRD) patterns confirm that CaSnO3 sintered at 1200°C exhibits orthorhombic structure. The evidence and rationale for two strong broad emission bands appeared at 360 and 780nm for undoped CaSnO3 are presented. The CL measurements exhibit that the 4f-4f emissions from (5)D4?(7)F6 (490nm), (5)D4 ?(7)F5 (544nm), (5)D4 ?(7)F4 (586nm) and (5)D4 ?(7)F3 (622nm), assigned to possible transitions of Tb(3+) ions are seen. The strongest one, observed at 544nm, due to its probability of both magnetic and electric transitions make the sample emission green. Emissions at 480, 574, 662 and 755nm were detected for the CaSnO3:Dy(3+) and attributed to the transitions from the (4)F9/2 to various energy levels (6)H15/2, (6)H13/2, (6)H11/2 and (6)H9/2+(6)F11/2 of Dy(3+), respectively. CL spectra of Eu doped CaSnO3 reveal that there is a strong emission peak appeared at 615nm due to the electric dipole transition (5)D0?(7)F2 (red). Finally, our results show that the rare earth doped CaSnO3 have remarkable potential for applications as optical materials since it exhibits efficient and sharp emission due to rare earth ions. PMID:25766113

  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. PMID:24245274

  5. 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.

  6. Structural transition in rare earth doped zirconium oxide: A positron annihilation study

    SciTech Connect

    Chakraborty, Keka [Applied Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)] [Applied Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Bisoi, Abhijit [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India)] [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Ganguly, Bichitra Nandi, E-mail: bichitra.ganguly@saha.ac.in [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Grover, Vinita; Sayed, Farheen Nasir; Tyagi, A.K. [Applied Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)] [Applied Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2012-11-15

    Graphical abstract: New microstructural analysis and phase transition of rare earth doped mixed oxide compounds such as: Sm{sub 2?x}Dy{sub x}Zr{sub 2}O{sub 7} (where x = 0.0 ? x ? 2.0) that are potentially useful as solid oxide fuels, ionic conductors, optoelectronic materials and most importantly as radiation resistant host for high level rad-waste disposal, structural transition in the system is reported through positron annihilation spectroscopy as there is an indication in the X-ray diffraction analysis. Highlights: ? Zirconium oxide material doped with rare earth ions. ? The method of positron annihilation spectroscopy suggests a phase transition in the system. ? The crystal structure transformation from pure pyrochlore to defect fluorite type of structure is shown by X-ray diffraction results. -- Abstract: A series of compounds with the general composition Sm{sub 2?x}Dy{sub x}Zr{sub 2}O{sub 7} (where 0 ? x ? 2.0) were synthesized by chemical route and characterized by powder X-ray diffraction (XRD) analysis. The rare earth ion namely Sm{sup +3} in the compound was gradually replaced with another smaller and heavier ion, Dy{sup +3} of the 4f series, there by resulting in order–disorder structural transition, which has been studied by positron annihilation lifetime and Doppler broadening spectroscopy. This study reveals the subtle electronic micro environmental changes in the pyrochlore lattice (prevalent due to the oxygen vacancy in anti-site defect structure of the compound) toward its transformation to defect fluorite structure as found in Dy{sub 2}Zr{sub 2}O{sub 7}. A comparison of the changes perceived with PAS as compared to XRD analysis is critically assayed.

  7. Silicon-germanium saturable absorbers and erbium-doped waveguides for integrated mode-locked lasers

    E-print Network

    Byun, Hyunil

    2006-01-01

    In this thesis, Silicon-Germanium (SiGe) Saturable Bragg Reflectors (SBR) and Erbium-doped waveguide chips are fabricated and characterized as crucial components for integration of a mode-locked laser on a Si-chip. The ...

  8. Low temperature synthesis of anatase rare earth doped titania-silica photocatalyst and its photocatalytic activity under solar-light

    Microsoft Academic Search

    Jianjun Zhu; Jimin Xie; Min Chen; Deli Jiang; Dan Wu

    2010-01-01

    A series of rare earth (Sm3+, Nd3+, Ce3+ and Pr3+) doped titania-silica photocatalysts, as a reclaimed solar-light responsive photocatalyst, was prepared by sol–gel method with TEOS and TBT as precursors, by keeping the molar of TEOS:TBT constant at 1:1 and with different rare earth dopant content. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning

  9. 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. PMID:23574429

  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 first two years in order to establish an effective implementation plan guaranteeing long term sustainability for the infrastructure and the associated services. We plan to describe the RIs to be integrated in EPOS and to illustrate the initial suite of integrated and thematic core services to be offered to the users. We will present examples of combined data analyses and we will address the importance of opening our research infrastructures to users from different communities. We will describe the use-cases identified so far in order to allow stakeholders and potential future users to understand and interact with the EPOS infrastructure. In this framework, we also discuss the global perspectives for data infrastructures in order to verify the coherency of the EPOS plans and present the EPOS contributions. We also discuss the international cooperation initiatives in which EPOS is involved emphasizing the implications for solid Earth data infrastructures. In particular, EPOS and the satellite Earth Observation communities are collaborating in order to promote the integration of data from in-situ monitoring networks and satellite observing systems. Finally, we will also discuss the priorities for the third year of activity and the key actions planned to better involve users in EPOS. In particular, we will discuss the work done to finalize the design phase as well as the activities to start the validation and testing phase of the EPOS infrastructure.

  11. On the optical properties of undoped and rare-earth-doped yttrium aluminium garnet single This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-print Network

    Collins, Gary S.

    On the optical properties of undoped and rare-earth-doped yttrium aluminium garnet single crystals.1088/0022-3727/45/1/015103 On the optical properties of undoped and rare-earth-doped yttrium aluminium garnet single crystals C R Varney, D may appear in colour only in the online journal) 1. Introduction Rare-earth-(RE)-doped yttrium

  12. Hydrothermal Synthesis, Microstructure and Photoluminescence of Eu3+-Doped Mixed Rare Earth Nano-Orthophosphates

    PubMed Central

    2010-01-01

    Eu3+-doped mixed rare earth orthophosphates (rare earth = La, Y, Gd) have been prepared by hydrothermal technology, whose crystal phase and microstructure both vary with the molar ratio of the mixed rare earth ions. For LaxY1–xPO4: Eu3+, the ion radius distinction between the La3+ and Y3+ is so large that only La0.9Y0.1PO4: Eu3+ shows the pure monoclinic phase. For LaxGd1–xPO4: Eu3+ system, with the increase in the La content, the crystal phase structure of the product changes from the hexagonal phase to the monoclinic phase and the microstructure of them changes from the nanorods to nanowires. Similarly, YxGd1–xPO4: Eu3+, Y0.1Gd0.9PO4: Eu3+ and Y0.5Gd0.5PO4: Eu3+ samples present the pure hexagonal phase and nanorods microstructure, while Y0.9Gd0.1PO4: Eu3+ exhibits the tetragonal phase and nanocubic micromorphology. The photoluminescence behaviors of Eu3+ in these hosts are strongly related to the nature of the host (composition, crystal phase and microstructure). PMID:21170409

  13. 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.

  14. 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 no convention or embedded data yields a suitable answer, the user is prompted to fill in the blanks. The OEF’s interaction libraries assist in the construction of user interfaces for data management. These libraries support data import, data prompting, data introspection, the management of the contents of a common data model, and the creation of derived data to support visualization. Finally, visualization libraries provide interactive visualization using an extended version of NASA WorldWind. The OEF viewer supports visualization of terrains, point clouds, 3D volumes, imagery, cutting planes, isosurfaces, and more. Data may be color coded, shaded, and displayed above, or below the terrain, and always registered into a common coordinate space. The OEF architecture is open and cross-platform software libraries are available separately for use with other software projects, while modules from other projects may be integrated into the OEF to extend its features. The OEF is currently being used to visualize data from EarthScope-related research in the Western US.

  15. 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 [Group of Applied Physics, University of Geneva, CH-1211 Geneva 4 (Switzerland); Riedmatten, Hugues de [Group of Applied Physics, University of Geneva, CH-1211 Geneva 4 (Switzerland); ICFO-Institute of Photonic Sciences, Mediterranean Technology Park, E-08860 Castelldefels (Barcelona) (Spain); ICREA-Institucio Catalana de Recerca i Estudis Avancats, E-08015 Barcelona (Spain)

    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.

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

    SciTech Connect

    Jeon, Sang-Chae; Kang, Suk-Joong L. [Materials Interface Laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373-1, Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)] [Materials Interface Laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373-1, Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    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}.

  17. Electron paramagnetic resonance of vanadyl doped mixed alkaline earth borate glasses

    NASA Astrophysics Data System (ADS)

    Samdani, Chandrasekhar, K.; Shareefuddin, Md.; Chary, M. Narasimha

    2013-06-01

    The "mixed alkaline effect" is one of the classical anomalies of glass science. We report here an interesting phenomenon "Mixed Alkaline earth oxide Effect" observed in a series of VO2+ ions doped in xMgO-(30-x)BaO-68B2O3-2V2O5 glass system. Glasses are investigated by EPR technique at X-band frequencies. The EPR spectra of all the glasses exhibited resonance signals characteristic of VO2+ ions in octahedral coordination with tetragonal compression and have C4V symmetry with ground state dxy. Tetragonality (?gll/?g?) of V4+ ion sites exhibited non-linear variation with MgO content, which indicated change in the ligand field at the site of V4+.

  18. Structures, Stabilities, and Electronic Properties for Rare-Earth Lanthanum Doped Gold Clusters

    NASA Astrophysics Data System (ADS)

    Zhao, Ya-Ru

    2015-02-01

    The structures, stabilities, and electronic properties of rare-earth lanthanum doped gold La2Aun (n = 1-9) and pure gold Aun (n ? 11) clusters have been investigated by using density functional theory. The optimized geometries show that the lowest energy structures of La2Aun clusters favour the 3D structure at n ? 3. The lanthanum atoms can strongly enhance the stabilities of gold clusters and tend to occupy the most highly coordinated position. By analysing the gap, vertical ionization potential, and chemical hardness, it is found that the La2Au6 isomer possesses higher stability for small-sized La2Aun clusters (n = 1-9). The charges in the La2Aun clusters transfer from La atoms to the Aun host. In addition, Wiberg bond indices analysis reveals that the intensity of different bonds of La2Aun clusters exhibits a sequence of La-La bond > La-Au bond > Au-Au bond.

  19. Coherent spectroscopy of rare-earth-metal-ion-doped whispering-gallery-mode resonators

    SciTech Connect

    McAuslan, D. L.; Korystov, D.; Longdell, J. J. [Jack Dodd Centre for Photonics and Ultra-Cold Atoms, Department of Physics, University of Otago, Dunedin, New Zealand. (New Zealand)

    2011-06-15

    We perform an investigation into the properties of Pr{sup 3+}:Y{sub 2}SiO{sub 5} whispering-gallery-mode resonators as a first step toward achieving the strong coupling regime of cavity QED with rare-earth-metal-ion-doped crystals. Direct measurement of cavity QED parameters are made using photon echoes, giving good agreement with theoretical predictions. By comparing the ions at the surface of the resonator to those in the center, it is determined that the physical process of making the resonator does not negatively affect the properties of the ions. Coupling between the ions and resonator is analyzed through the observation of optical bistability and normal-mode splitting.

  20. 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.

  1. 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.

  2. Spectroscopic investigation of rare-earth-doped chloride single crystals for telecommunications amplifiers

    NASA Astrophysics Data System (ADS)

    Isaenko, Ludmila I.; Yelisseyev, Alexander P.; Nadolinny, Vladimir A.; Pashkov, Victor I.; Nostrand, Mike C.; Page, Ralph H.; Payne, Stephen A.; Solarz, Richard W.

    1998-05-01

    In single crystals of AgCl, BaCl2, PbCl2, SrCl2, KPb2Cl5 with an unextended phonon spectrum (E less than 200 cm-1), doped by Dy, the luminescence spectrum was found to cover a wide range from visible region to IR (4.3 mkm for KPb2Cl5), including well pronounced 1.31 mkm band, which is important for using in telecommunication amplifiers. The Rare Earth impurity was shown to enter the host matrice as RE3+ in chlorides, the only type of impurity centers being formed in the case of rhombic MeCl2 crystals with Me equals Ba, P, S.

  3. Superparamagnetism and interfacial superconductivity in rare earth Pr-doped Ca122

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    To better understand the origin of the non-bulk superconductivity with an unusually high onset-Tc (49 K) and its superconducting behavior in the rare earth Pr-doped Ca122 [(Ca1-xPrx)Fe2As2], detailed chemical analyses and magnetization measurements on both the as-synthesized and annealed single crystals were carried out. A small but non-negligible As-deficiency and superparamagnetic clusters (SPCs) were detected in the superconducting as-synthesized crystals, suggesting that the SPCs originate from the As vacancies. The magnetic moment of the SPC were found to be insensitive to the doping level x, while the SPC density (n) is zero for x 0.05 in the non-superconducting region and increases monotonically with x for x 0.1 in the superconducting region. The superconducting volume fraction (f) was shown to be very closely related with n. Noticeable inter-cluster interactions, from antiferromagnetic for x 0.05 (non -SC region) to weakly ferromagnetic for x 0.1 (SC region) were found, suggesting that the defects are ordered. Systematically annealing the crystals over 500-920^o simultaneously suppress both n and f. Therefore, we propose that the ordered vacancies, and the associated interfaces, are responsible for the rather high onset-Tc.

  4. Potential rare earth free permanent magnet: interstitial boron doped FeCo

    NASA Astrophysics Data System (ADS)

    Khan, Imran; Hong, Jisang

    2014-10-01

    Using the full potential linearized augmented plane wave method, we investigated the structural and the magnetic properties of boron doped FeCo. After fully relaxing the lattice structure, the interatomic distances between boron and Fe atoms were found to be greatly enhanced and the tetragonal distortion was realized due to this increased interatomic distance. Nonetheless, both the unit cell volume and the total magnetic moment of the tetragonally distorted FeCo structure were weakly suppressed compared with those of ideal bulk FeCo. We found a magnetocrystalline anisotropy constant of 0.8 MJ m-3 and this was mainly due to the tetragonal distortion induced by boron impurity, not from the hybridization effect with Fe or Co, because no essential change in the magnetocrystalline anisotropy constant was found even without boron impurity in the lattice distorted system. Additionally, the estimated maximum energy product and coercive field were 100 MGOe and 745 kA m-1, respectively. These results may imply that the interstitial boron doped FeCo can be used for a potential rare earth free permanent magnet although those values are likely to be suppressed in real samples due to micromagnetic factors.

  5. Sol-gel-derived hybrid materials multi-doped with rare-earth metal ions

    NASA Astrophysics Data System (ADS)

    Zelazowska, E.; Rysiakiewicz-Pasek, E.; Borczuch-Laczka, M.; Cholewa-Kowalska, K.

    2012-06-01

    Four different hybrid organic-inorganic materials based on TiO2-SiO2 matrices with organic additives and doped with rare-earth metal ions (III) from the group of europium, cerium, terbium, neodymium, dysprosium and samarium, were synthesized by sol-gel method. Tetraethyl orthosilicate, titanium (IV) isopropoxide and organic compounds, such as butyl acrylate, butyl methacrylate, ethyl acetoacetate, ethylene glycol dimethacrylate, ethyl acetate, propylene carbonate, organic solvents and certain inorganic salts were used in the synthesis. The inorganic part of the sols, which were used in the synthesis of all the hybrid materials, was prepared separately and then the organic parts were added. The materials obtained were aged for three weeks at room temperature and then heated in an electric oven for three hours at temperatures of 80 °C-150 °C. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDX); X-ray diffraction (XRD); Fourier transform infrared spectroscopy (KBr technique); 29Si magic-angle spinning nuclear magnetic resonance; and fluorescence spectroscopy were used for the examination of morphology, microstructure and luminescence properties, respectively. Photoluminescence properties with relatively intense narrow emission lines of Tb, Eu, Dy, Nd, Sm respectively to the RE-ions doping, were observed for all the hybrid materials.

  6. 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 seismic tomography may be sliced by multiple oriented cutting planes and isosurfaced to create 3D skins that trace feature boundaries within the data. Topography may be overlaid with satellite imagery, maps, and data such as gravity and magnetics measurements. Multiple data sets may be visualized simultaneously using overlapping layers within a common 3D coordinate space. Data management within the OEF handles and hides the inevitable quirks of differing file formats, web protocols, storage structures, coordinate spaces, and metadata representations. Heuristics are used to extract necessary metadata used to guide data and visual operations. Derived data representations are computed to better support fluid interaction and visualization while the original data is left unchanged in its original form. Data is cached for better memory and network efficiency, and all visualization makes use of 3D graphics hardware support found on today's computers. The OpenEarth Framework project is currently prototyping the software for use in the visualization, and integration of continental scale geophysical data being produced by EarthScope-related research in the Western US. The OEF is providing researchers with new ways to display and interrogate their data and is anticipated to be a valuable tool for future EarthScope-related research.

  7. IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 8, NO. 4, JULY/AUGUST 2002 749 Rare-Earth-Doped GaN: Growth, Properties, and

    E-print Network

    Steckl, Andrew J.

    IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 8, NO. 4, JULY/AUGUST 2002 749 Rare-Earth is presented of the fabrication, operation, and applications of rare-earth-doped GaN electroluminescent devices (ELDs). GaN:RE ELDs emit light due to impact excitation of the rare earth (RE) ions by hot carriers

  8. 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.

  9. Effect of rare earth doping on thermo-physical properties of lanthanum zirconate ceramic for thermal barrier coatings

    Microsoft Academic Search

    Hongming ZHOU; Danqing YI

    2008-01-01

    The effect of rare earth doping on thermo-physical properties of lanthanum zirconate was investigated. Oxide powders of various compositions La2Zr2O7 were synthesized by coprecipitation-calcination method. High-temperature dilatometer, DSC, and laser thermal diffusivity methods were used to analyze thermal expansion coefficient (TEC), specific heat, and thermal diffusivity. The results showed that CeO2 doped pyrochlores La2(Zr1.8Ce0.2)2O7 and La1.7(DyNd)0.15(Zr0.8Ce0.2)2O7 had higher TEC than

  10. 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 disciplines to cooperate and exchange views on the common theme of ‘linking data and modelling', leading to a better understanding of local processes within a global context. Computational and conceptual models of the Earth system provide the ability to investigate different scenarios in biogeochemistry, such as the carbon cycle, the structure of marine sediments, and isotope distribution in climate components. Training and education, especially in time-series and data analysis, is a common key component for all participants. The Helmholtz Graduate School for Polar and Marine Research (POLMAR) (polmar.awi.de), beyond the aforementioned programmes in further cooperation with the Max Planck Institute for Marine Microbiology, Bremen, the University of Potsdam, Bremerhaven University of Applied Science and the Institute for Marine Resources (IMARE), provides a consistent framework for education and qualification for PhD students in general. Developing all categories of skills needed for analysing complex climate and environmental systems and the development of integrated solutions in a supportive network of collaborating research institutions fosters outstanding career options. Structured scientific training and supervision supported by a broad range of transferable skills development courses is indicative for the entire concept. This structured and integrated educational concept provides a strong basis for qualifying the next generation of excellent scientists for the challenging questions in Earth System Science and Polar and Marine Research.

  11. Postgraduate Education in Earth and Environmental Sciences: an Integrated Concept

    NASA Astrophysics Data System (ADS)

    Grosfeld, K.; Lohmann, G.; Ladstätter-Weißenmayer, A.; Burrows, J.; Sprengel, C.; Bijma, J.

    2009-04-01

    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 (Uni-HB), 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 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. The foundation of an Earth System Research School (ESSReS) (www.earth-system-science.org) at the AWI enables PhD students from a variety of disciplines to cooperate and exchange views on the common theme of ‘linking data and modelling', leading to a better understanding of local processes within a global context. Computational and conceptual models of the Earth system provide the ability to investigate different scenarios in biogeochemistry, such as the carbon cycle, the structure of marine sediments, and isotope distribution in climate components. Training and education, especially in time-series and data analysis, is a common key component for all participants. The Helmholtz graduate school for Polar and Marine Research (POLMAR) (polmar.awi.de), beyond the aforementioned programmes in further cooperation with the Max Planck Institute for Microbiology, Bremen, the University Potsdam, Bremerhaven University of Applied Science and the Institute for Marine Resources (IMARE), provides a consistent framework for education and qualification for PhD students in general. Developing all categories of skills needed for analysing complex climate and environmental systems and the development of integrated solutions in a supportive network of collaborating research institutions fosters outstanding career options. Structured training and supervision supported by a broad range of transferrable skill development courses is indicative for the entire concept. This structured and integrated educational concept provides a strong basis for qualifying the next generation of excellent scientists for the challenging questions in Earth System Science and Polar and Marine Research.

  12. Materials Science and Engineering B105 (2003) 9196 Photoluminescence studies of rare earth (Er, Eu, Tm) in situ doped GaN

    E-print Network

    Steckl, Andrew J.

    doping of wide band-gap semiconductors such as GaN, AlN, and SiC has led to the observation of intense RE, Tm) in situ doped GaN U. Hömmericha,, Ei Ei Nyeina, D.S. Leeb, J. Heikenfeldb, A.J. Stecklb, J The emission properties of rare earth (RE)-doped GaN are of significant current interest for applications

  13. Film properties and integration performance of carbon doped oxides

    Microsoft Academic Search

    H. M'Saad

    2004-01-01

    Summary form only given. The semiconductor industry has witnessed a successful introduction of copper based interconnects and low permittivity insulators with 130nm node devices. The advent of 90nm node devices has led to the introduction of first generation of carbon doped dielectric films. Further scaling will require materials with lower permittivity and this has accelerated the development of a second

  14. Advancing coupled human-earth system models: The integrated Earth System Model Project

    NASA Astrophysics Data System (ADS)

    Thomson, A. M.; Edmonds, J. A.; Collins, W.; Thornton, P. E.; Hurtt, G. C.; Janetos, A. C.; Jones, A.; Mao, J.; Chini, L. P.; Calvin, K. V.; Bond-Lamberty, B. P.; Shi, X.

    2012-12-01

    As human and biogeophysical models develop, opportunities for connections between them evolve and can be used to advance our understanding of human-earth systems interaction in the context of a changing climate. One such integration is taking place with the Community Earth System Model (CESM) and the Global Change Assessment Model (GCAM). A multi-disciplinary, multi-institution team has succeeded in integrating the GCAM integrated assessment model of human activity into CESM to dynamically represent the feedbacks between changing climate and human decision making, in the context of greenhouse gas mitigation policies. The first applications of this capability have focused on the feedbacks between climate change impacts on terrestrial ecosystem productivity and human decisions affecting future land use change, which are in turn connected to human decisions about energy systems and bioenergy production. These experiments have been conducted in the context of the RCP4.5 scenario, one of four pathways of future radiative forcing being used in CMIP5, which constrains future human-induced greenhouse gas emissions from energy and land activities to stabilize radiative forcing at 4.5 W/m2 (~650 ppm CO2 -eq) by 2100. When this pathway is run in GCAM with the climate feedback on terrestrial productivity from CESM, there are implications for both the land use and energy system changes required for stabilization. Early findings indicate that traditional definitions of radiative forcing used in scenario development are missing a critical component of the biogeophysical consequences of land use change and their contribution to effective radiative forcing. Initial full coupling of the two global models has important implications for how climate impacts on terrestrial ecosystems changes the dynamics of future land use change for agriculture and forestry, particularly in the context of a climate mitigation policy designed to reduce emissions from land use as well as energy systems. While these initial experiments have relied on offline coupling methodologies, current and future experiments are utilizing a single model code developed to integrate GCAM into CESM as a component of the land model. This unique capability facilitates many new applications to scientific questions arising from human and biogeophysical systems interaction. Future developments will further integrate the energy system decisions and greenhouse gas emissions as simulated in GCAM with the appropriate climate and land system components of CESM.

  15. Integration of satellite fire products into MPI Earth System Model

    NASA Astrophysics Data System (ADS)

    Khlystova, Iryna G.; Kloster, Silvia

    2013-04-01

    Fires are the ubiquitous phenomenon affecting all natural biomes. Since the beginning of the satellite Era, fires are being continuously observed from satellites. The most interesting satellite parameter retrieved from satellite measurements is the burned area. Combined with information on biomass available for burning the burned area can be translated into climate relevant carbon emissions from fires into the atmosphere. In this study we integrate observed burned area into a global vegetation model to derive global fire emissions. Global continuous burned area dataset is provided by the Global Fire Emissions Dataset (GFED). GFED products were obtained from MODIS (and pre-MODIS) satellites and are available for the time period of 14 years (1997-2011). This dataset is widely used, well documented and supported by periodical updates containing new features. We integrate the global burned area product into the land model JSBACH, a part of the Earth-System model developed at the Max Plank Institute for Meteorology. The land model JSBACH simulates land biomass in terms of carbon content. Fire is an important disturbance process in the Earth's carbon cycle and affects mainly the carbon stored in vegetation. In the standard JSBACH version fire is represented by process based algorithms. Using the satellite data as an alternative we are targeting better comparability of modeled carbon emissions with independent satellite measurements of atmospheric composition. The structure of burned vegetation inside of a biome can be described as the balance between woody and herbaceous vegetation. GFED provides in addition to the burned area satellite derived information of the tree cover distribution within the burned area. Using this dataset, we can attribute the burned area to the respective simulated herbaceous or woody biomass within the vegetation model. By testing several extreme cases we evaluate the quantitative impact of vegetation balance between woody and herbaceous vegetation on fire carbon emissions. The integration procedure of satellite observed burned area into JSBACH is developed in a way that it can be easily adapted to future satellite fire datasets (e.g. expected ESA CCI Fire-ECV products). Here we will also discuss further possibilities for the integration of satellite fire data into vegetation models.

  16. Effect of microstructure, grain size, and rare earth doping on the electrorheological performance of nanosized particle materials

    E-print Network

    Gao, Song

    and grain sizes were prepared by doping TiO2 or ZrO2 with rare earth (RE) elements, and by changing in the grain. Body-centered tetragonal TiO2 and tetragonal ZrO2 possess higher ER activity than tetragonal TiO2 and monoclinic ZrO2, respectively. The effect of grain size on ER performance should not be neglected

  17. Magnetooptics and magnetic ordering in ferrite nanoparticles in glass doped with iron and rare-earth elements

    Microsoft Academic Search

    O. S. Ivanova; I. S. Edelman; R. D. Ivantsov; V. N. Zabluda; S. A. Stepanov; S. M. Zharkov; G. M. Zeer; Ya. V. Zubavichus; A. A. Veligzhanin; J. Curely

    2011-01-01

    Magnetic circular dichroism and X-ray diffraction were used to investigate the structure and magnetooptical properties of\\u000a nanoparticles formed in potassium-aluminum-germanium-boron glass doped with iron and rare-earth elements. It is demonstrated\\u000a that in thermally processed glass, the main magnetic phase of the formed nanoparticles is ?-Fe2O3 maghemite.

  18. Highly transparent and conductive rare earth-doped ZnO thin films prepared by magnetron sputtering

    Microsoft Academic Search

    Tadatsugu Minami; Takashi Yamamoto; Toshihiro Miyata

    2000-01-01

    Highly transparent and conductive thin films of ZnO doped with a rare-earth element, Sc or Y, have been prepared by d.c. magnetron sputtering using a powder target. The resistivity of the ZnO:Sc thin films was always lower than that of the ZnO:Y thin films; a resistivity in the order of 10?4 ? cm was obtained in these films. The resistivity

  19. Features of an intermetallic n-ZrNiSn semiconductor heavily doped with atoms of rare-earth metals

    SciTech Connect

    Romaka, V. A., E-mail: vromaka@polynet.lviv.ua [National Academy of Sciences of Ukraine, Ya. Pidstryhach Institute for Applied Problems of Mechanics and Mathematics (Ukraine); Fruchart, D.; Hlil, E. K. [CNRS, Institute Neel (France); Gladyshevskii, R. E. [Ivan Franko Lviv National University (Ukraine); Gignoux, D. [CNRS, Institute Neel (France); Romaka, V. V.; Kuzhel, B. S. [Ivan Franko Lviv National University (Ukraine); Krayjvskii, R. V. [Lvivska Politechnika National University (Ukraine)

    2010-03-15

    The crystal structure, density of electron states, electron transport, and magnetic characteristics of an intermetallic n-ZrNiSn semiconductor heavily doped with atoms of rare-earth metals (R) have been studied in the ranges of temperatures 1.5-400 K, concentrations of rare-earth metal 9.5 x 10{sup 19}-9.5 x 10{sup 21} cm{sup -3}, and magnetic fields H {<=} 15 T. The regions of existence of Zr{sub 1-x}R{sub x}NiSn solid solutions are determined, criteria for solubility of atoms of rare-earth metals in ZrNiSn and for the insulator-metal transition are formulated, and the nature of 'a priori doping' of ZrNiSn is determined as a result of redistribution of Zr and Ni atoms at the crystallographic sites of Zr. Correlation between the concentration of the R impurity, the amplitude of modulation of the bands of continuous energies, and the degree of occupation of potential wells of small-scale fluctuations with charge carriers is established. The results are discussed in the context of the Shklovskii-Efros model of a heavily doped and compensated semiconductor.

  20. Ceramics and amorphous thin films based on gallium sulphide doped by rare-earth sulphides

    NASA Astrophysics Data System (ADS)

    Popescu, M.; Sava, F.; L?rinczi, A.; Velea, A.; Simandan, I. D.; Badica, P.; Burdusel, M.; Galca, A. C.; Matei, E.; Preda, N.; Secu, M.; Socol, G.; Jipa, F.; Zamfirescu, M.; Balan, A.

    2015-04-01

    Bulk ceramics of Ga2S3 and rare-earth sulfides (EuS, Gd2S3, Er2S3) as well as combinations thereof have been prepared by spark plasma sintering (SPS). The disk-shaped ceramics were used as targets for pulsed laser deposition (PLD) experiments to obtain amorphous thin films. The properties of these new bulks and amorphous thin films have been investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), optical transmission spectroscopy, and atomic force microscopy (AFM). In order to test the photoexpansion effect in Ga2S3 and the possibility to create planar arrays of microlenses, the film was irradiated with femtosecond laser pulses at different powers. For low laser power pulses (up to 100 mW power per pulse) a photoexpansion effect was observed, which leads to formation of hillocks with a height of 40–50 nm. EuS doped Ga2S3 thin film shows luminescence properties, which recommend them for optoelectronic applications.

  1. Synthesis, Structural and Magnetic Characterization of Rare Earth Doped SrMnO3 Compounds

    NASA Astrophysics Data System (ADS)

    Juarez-Rosete, M. A.; Chavira, E.; Betancourt, J. I.; Marinero, E. E.; Bucio, L.; Bokhimi, X.

    2012-02-01

    We report on our ongoing work on the synthesis, characterization and magnetic studies of Rare Earth (RE) containing RE-SrMnO3 compounds. The aim of the study is to determine how different RE elements influence the magnetic properties of said materials. We have so far investigated the incorporation of Dy and Yb into the SrMnO3 unit cell. To this effect we have employed solid state reaction synthesis methods to fabricate said compounds. The reaction products evolution were monitored as a function of time by XRD, TGA and SEM. Measurements of lattice parameters and Rietveld refinement of the XRD spectra, indicate that Dy and Yb are incorporated substitutionally in SrMnO3. Temperature dependent magnetic measurements, on the other hand, reveal a common transition temperature around 41 K for both Dy and Yb doped SrMnO3. We are in the process of synthesizing additional materials containing additional RE elements to investigate how the electronic properties of said RE may influence the magnetic properties of these compounds.

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

    SciTech Connect

    Neal, John S [ORNL; Boatner, Lynn A [ORNL; Ramey, Joanne Oxendine [ORNL; Wisniewski, D. [Institute of Physics, Nicolaus Copernicus University, Toru?, Poland; Kolopus, James A [ORNL; Cherepy, Nerine [Lawrence Livermore National Laboratory (LLNL); Payne, Stephen A. [Lawrence Livermore National Laboratory (LLNL)

    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.

  3. Exchange interaction in rare-earth-doped IV-VI diluted magnetic semiconductors

    NASA Astrophysics Data System (ADS)

    Górska, M.; Anderson, J. R.; Kido, G.; Green, S. M.; Go?acki, Z.

    1992-05-01

    The magnetization and magnetic susceptibility of Bridgman-grown Sn1-xGdxTe samples with values of x up to 0.09 have been measured in fields up to 5.5 T over a temperature range from 2 to 300 K and in fields up to 23 T at 4.2 K. The low-field, high-temperature susceptibility data followed the Curie-Weiss relation with a small Curie temperature. The magnetic-field dependence of the magnetization was fitted to an expression containing a Brillouin function, representing isolated magnetic ions, plus a term representing pair interactions. Both the susceptibility and the high-field magnetization data indicated a weak antiferromagnetic coupling among Gd ions. These results are compared with our previously obtained exchange parameters for Pb1-xGdxTe and Pb1-xEuxTe. The exchange interaction in Sn1-xGdxTe is larger than in PbTe-based, rare-earth-doped chalcogenides, in agreement with the smaller cation-anion spacing in SnTe-based compounds. A ferromagnetic or spin-glass ordering due to the possible Ruderman-Kittel-Kasuya-Yosida interaction in Sn1-xGdxTe with high hole concentration was not observed.

  4. 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 1550 nm excitation reported to date for UV, green, red and NIR emissions, which makes them potential candidates for many photonic applications. In addition, UC mechanisms were proposed in these phosphors based on the time resolved spectroscopic measurements, including concentration, and power dependence studies. Potential applications of these phosphors in different areas such as solar cells, displays, etc. have been explored depending on the measured absolute quantum yield as well as color coordinate measurements. In addition, the application of nanophosphors for bioimaging application has been explored. Results from imaging of the nanoparticles together with aggregates of cultured cells have been studied. In vitro toxicity tests were conducted too. Nanoparticles internalization into the nucleus and cytoplasm were conformed using 3D reconstruction of the Z-stack images collected using the confocal mode of the two photon microscope. Measurement of the magnetization of the phosphor was conducted to study the paramagnetic strength of these Gd based nanoparticles. Magnetic resonance imaging with better contrast was also collected using these particles. Finally, the application of these UC phosphors for solar cell and display has been discussed briefly.

  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. Integrating Undergraduate Research and Teaching in Environmental Education: Ohio State's Earth Day Project

    Microsoft Academic Search

    Pamela A. Wright; Donald W. Floyd

    1992-01-01

    Research, teaching, and outreach are often separated in academic objectives, but the potential benefits of integration are many, particularly in the field of environmental education. Students at The Ohio State University, School of Natural Resources, participated in a project designed to integrate research and service with teaching during Earth Week, 1990. The students administered an Earth Day Environmental IQ Test

  7. http://lfw.pennnet.com/Articles/Article_Display.cfm?Section=ARTCL&ARTICLE_ID=243242&VERSION_NUM=3&p=12 Visible rare-earth-doped laser is fabricated on silicon

    E-print Network

    Steckl, Andrew J.

    =12 Visible rare-earth-doped laser is fabricated on silicon Much research on photonic devices will likely be a family of rare-earth (RE)-doped gallium nitride (GaN) coherent light emitters, most of which sufficient charge density in a p- i-n structure to generate the necessary density of excited rare-earth ions

  8. Integrating spacecraft and aircraft in Earth Observation System architectures

    E-print Network

    Suarez, Brandon H

    2011-01-01

    The Global Earth Observation System (GEOS) is the essential data gathering network that enables the advancement of Earth science. In recent years, efforts have been made to understand the major GEOS architectural tradeoffs. ...

  9. 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

  10. 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.

  11. Down Converter Device Combining Rare-Earth Doped Thin Layer and Photonic Crystal for c-Si Based Solar Cell

    E-print Network

    Deschamps, Thierry; Peretti, Romain; Lalouat, Loïc; Fourmond, Erwann; Fave, Alain; Guille, Antoine; Pereira, António; Moine, Bernard; Seassal, Christian

    2013-01-01

    The aim of the study is to develop ultra-compact structures enabling an efficient conversion of single high energy photon (UV) to two lower energy photons (IR). The proposed structure combines rare-earths doped thin layer allowing the down-conversion process with a photonic crystal (PhC), in order to control and enhance the down-conversion using optical resonances. On the top of the rare-earths doped layer, a silicon nitride (SiN) 2D planar PhC is synthesized. For that, SiN is first deposited by PECVD. After holographic lithography and reactive ion etching, a periodic square lattice of holes is generated on the SiN layer. The PhC topographical parameters as well as the layers thickness are optimized using Finite-Difference-Time-Domain simulations. The design and realization of such PhC-assisted down-converter structures is presented. Optical simulations demonstrate that the PhC leads to the establishment of resonant modes located in the underneath doped layer, allowing a drastic enhancement of the absorption ...

  12. 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.

  13. 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

  14. Enhanced laser cooling of rare-earth-ion-doped nanocrystalline powders

    NASA Astrophysics Data System (ADS)

    Ruan, X. L.; Kaviany, M.

    2006-04-01

    The enhanced laser cooling performance of rare-earth-ion-doped nanocrystalline powders is predicted, compared to the bulk material, using Yb3+:Y2O3 as the model material. This is achieved by enhancing the off-resonance, phonon-assisted absorption, which is proportional to the three factors considered in this paper: the dopant concentration, the pumping field energy, and the excitation coefficient. Using the energy transfer theory for concentration quenching, the optimum concentration corresponding to the maximum cooling power is found to be considerably larger than the currently used value, suggesting noticeable enhancement effects for laser cooling. The pumping field energy is enhanced in random nanopowders compared with bulk crystals under the same irradiation, due to the multiple scattering of photons. Photons are thus localized in the medium and do not propagate through, increasing the photon absorption of the pumping beam (and it is shown that the reabsorption of the fluorescence is negligible). Using molecular dynamics simulations, the phonon density of states (DOS) of the nanopowder is calculated, and found to have broadened modes, and extended small tails at low and high frequencies. The second-order electronic transition rate for the anti-Stokes luminescence is calculated using the Fermi golden rule, which includes the influence of this phonon DOS, and is shown to have enhancement effects on the laser cooling efficiency using nanopowders. It is finally concluded that these three enhancement mechanisms are essentially to increase the population of the three participating carriers (electron, photon, and phonon) in the interacting volume, and this also points out directions for enhancing laser cooling performance in bulk materials.

  15. Study of structure and magnetic properties of rare earth doped BiFeO3

    NASA Astrophysics Data System (ADS)

    Suresh, Pittala; Srinath, S.

    2014-09-01

    RExBi1-xFeO3 (RE=La, Gd and Ho) samples were synthesized by a solid state reaction method and investigated for structure and magnetic properties. XRD shows that La and Ho dopings at A-site effectively reduce the secondary phase formation. A structural phase transition is observed to orthorhombic phase with all RE elements above certain concentration limit. La doping results in the observation of huge coercivity of 10 kOe and Ho doping results in high magnetic moment among all the RE elements. Gd and Ho doped samples show a pinching in the M-H loops with minimum HC.

  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 microstructural change of the coatings after various heat treatments at 1200°C and 1300°C showed evidence of crack healing and grain growth. Comparison between the rare-earth dopant distribution of a selected coating before and after a 1300°C/50 hr heat treatment suggests the possibility of dopant rearrangement, which can further increase the thermal conductivity. An explanation on the difference in the properties of the rare-earth doped coatings produced by SPS and conventional processes was discussed.

  17. Comparison of various organic compounds destruction on rare earths doped Ti/Sb-SnO2 electrodes.

    PubMed

    Cui, Yu-Hong; Feng, Yu-Jie; Liu, Junfeng; Ren, Nanqi

    2012-11-15

    Ti/Sb-SnO2 and three kinds of rare earths (REs), namely Ce, Gd, and Eu doped Ti/Sb-SnO2 electrodes were prepared and tested for their capacity on electrocatalytic degradation of three kinds of basal aromatic compounds (benzoquinone, hydroquinone and catechol) and six kinds of aliphatic acids (maleic acid, fumaric acid, succinic acid, malonic acid, oxalic acid and acetic acid). The elimination of selected organics as well as their TOC removal with different doped Ti/Sb-SnO2 electrodes was described by first-order kinetics. Compared with Ti/Sb-SnO2, the Gd and Eu doped electrodes show better performance on the degradation of most of the selected organics, while Ce doped electrode shows either closely or lower efficiency on the degradation of these selected organics. Besides electrode material, the molecular structure of organic compound has obvious effect on its degradation in the electrocatalytic process. Catechol is more resistant to the electrophilic attack by hydroxyl radicals than benzoquinone and hydroquinone. The compound with more complicate molecular structure or longer carbon chain is more difficult to be mineralized. The aliphatic acid with higher oxygen content or more double bonds is more readily to be oxidized in the electrocatalytic process. PMID:23022412

  18. Disordered electronic and magnetic systems - Transition metal (manganese) and rare earth (gadolinium) doped amorphous group IV semiconductors (carbon, silicon, germanium)

    NASA Astrophysics Data System (ADS)

    Zeng, Li

    2007-12-01

    While the physics of electrical doping of semiconductors has been well understood for decades, magnetic doping and the interactions between the carriers and the magnetic moments in semiconductors are still under active investigation for various applications, such as spintronics and quantum computing. Our systematic studies on transition-metal-doped (TM-doped) and rare-earth-doped (RE-doped) amorphous group IV elemental semiconductors provide unique insight into the rich physics of this type of materials. Our model system is the e-beam coevaporated a-GdxSi1-x films. Magnetron cosputtered a-GdxSi 1-x films, despite having very different film morphology at the 10-nm scale from the e-beam coevaporated films, are demonstrated to possess almost the same physical properties. Cosputtered a-GdxC1-x (:Hy) and Gd ion-implanted ta-C (ta-C1-x:Gd x) films are studied for Gd in different a-C matrices with different sp2/sp 3 ratio. All doped a-C films are on the insulating side of the metal-insulator transition. Very similar to a-Gd xSi1-x films, Gd possesses a large magnetic moment in a-C. The moment-moment and moment-carrier interactions lead to a spin-glass ground state and large negative magnetoresistance (MR) below a crossover temperature T' in both a-Gd xC1-x<(:Hy) and ta-C1-x:Gdx films. A small positive MR is found above T'. Transition metal Mn has always been believed to possess a large local moment in Si or Ge. However, e-beam coevaporated a-MnxSi1-x films are found to show a quenched local moment for Mn concentration as low as x=0.005 and up to x=0.175. All films are purely paramagnetic and have very small saturation moments. Unlike Gd, which provides both carriers and local moment, Mn only provides electrical carriers in a-Si. These results suggest an itinerant non-magnetic Mn states in a-Si; the insulating behavior is a result of the strong structural disorder. This quenching of the local Mn moment has not been predicted by any existing theory. Consistent with the small Mn moment, a-MnxSi1- x films show a very small positive MR, in contrast to Gd-doped films.

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

    SciTech Connect

    Katsumata, Toru, E-mail: katsumat@toyo.jp; Morita, Kentaro; Komuro, Shuji; Aizawa, Hiroaki [Faculty of Science and Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-8585 (Japan)

    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. 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, E-mail: byan@tongji.edu.cn; 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.

  1. Frequency upconversion and imaging using rare-earth doped colloidal nanoprobes

    E-print Network

    Polman, Albert

    ) europium terbium erbium Electronic structure: ...4fn5s2p6 internal 4f transitions · excellent;Terbium-doped SiO2 colloids: photoluminescence =2.4 ms PL also for unannealed colloids Lifetime increases passivation =3900) #12;CONCLUSIONS: Silica colloids doped with optically active: terbium (550 nm) europium

  2. Integrated Geophysical Support for the UK Earth Science Community

    NASA Astrophysics Data System (ADS)

    England, R. W.; Brisbourne, A. M.; Hawthorn, D.; Lane, V. S.

    2009-12-01

    The UK’s Natural Environment Research Council (NERC) has supported a Geophysical Equipment Facility for over 30 years. The primary role of this facility is to supply equipment (GPS, GPR, seismic and E-M) to the UK academic community for both land and marine experiments. The Facility therefore has the capacity to support integrated onshore-offshore and multi-observation experiments worldwide. Recent multinational experiments have addressed topics as diverse as continental rifting and the development of magmatic continental margins (The EAGLE Project and the Afar Consortium); the effect of tidal forcing on the flow of Antarctic Glaciers; mantle processes, lithospheric structure and the evolution of Hudson Bay; and the earthquake risk in Sumatra. Results from all of these experiments are causing us to change the way in which we look at planet Earth. Partly as a result of the IRIS success story, over the last 10 years significantly more emphasis has been placed on data management, archiving and distribution. In particular, the onshore seismic node of the facility (SEIS-UK) archives all of its data with IRIS DMC so that it subsequently becomes publicly available. The service provided by IRIS ensures that these new high-quality datasets are available worldwide in perpetuity. Data therefore have longevity far beyond the initial project funding period, augmenting and diversifying the initial scientific goals. This potentially adds considerable value to data and justifies continued support for large integrated facilities. It can also promote further international collaboration and scientific development at negligible cost. In the future, if their existence is to be justified, facilities will increasingly need to consider the impact their activities have on the science they support and the society supporting them. Facilities cannot afford to be passive in this endeavour. SEIS-UK is currently involved in the development of new technologies such as telemetry and low-power data logging systems to extend scientific observation to the furthest reaches of the planet. Also, an equipment upgrade process is in place to ensure users always have state of the art equipment to call on. Whilst maintaining links with IRIS, SEIS-UK is also developing links with European networks and groups which will ensure that its equipment and data are even more widely accessible and, more importantly, used.

  3. 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...

  4. Photoinduced second-harmonic generation in fibers doped with rare-earth ions.

    PubMed

    Dianov, E M; Kornienko, L S; Rybaltovsky, A O; Chernov, P V; Yatsenko, Y P

    1994-04-01

    Photoinduced second-harmonic generation in silica fibers doped with Er(3+), Sm(3+), and Tb(3+) has been investigated. Er(3+)-doped fibers have been found to tune a chi((2)) grating easily to the mode structure of the laser radiation, whereas Sm(3+)-doped fibers have been found to possess the greatest resistance to chi((2)) grating erasure by radiation at 532 nm. From the beginning of the preparation processes, the third harmonic at 355 nm is registered in all the fibers. PMID:19844333

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

    SciTech Connect

    Guo, Xiaobin; Xi, Li, E-mail: xili@lzu.edu.cn; Li, Yue; Han, Xuemeng; Li, Dong; Wang, Zhen; Zuo, Yalu [Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2014-08-18

    Magnetic damping constant (?) 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 ? based on the ferromagnetic resonance technique. Gd doping not only can efficiently decrease the magnetic inhomogeneity and the extrinsic part of ? but also the Landé g-factor and intrinsic part of ?. The obtained ? was roughly proportional to (g-2){sup 2} and the magnetic anisotropic constant, indicating that the decreased spin-orbit interaction decreases ? by Gd doping.

  6. Information Technology Infusion Case Study: Integrating Google Earth into the A-Train Data Depot

    NASA Astrophysics Data System (ADS)

    Smith, P. M.; Kempler, S. J.; Leptoukh, G. G.; Chen, A.

    2010-12-01

    The purpose of the NASA funded project, ‘Utilizing 3 Dimensional Data Views to Access Data and Discover Relationships Between Multiple Heterogeneous Data Sets Along the A-Train Tracks’ (Kempler, PI, NASA ROSES NNH07ZDA001N ACCESS Proposal) was to employ the latest 3 dimensional visualization technology to explore and provide direct data access to heterogeneous A-Train datasets, ‘operationally’, along, and on either side of the A-Train tracks. Google Earth (tm) provides the foundation for organizing, visualizing, publishing, and synergizing Earth science data in virtual 3 dimensions, for this project. Successful integration of Google Earth (tm) into the A-Train Data Depot (ATDD), resulted in: a) visualizing two-, three- and four-dimensional Earth science data on Google Earth (tm); b) visualizing and synergizing analyzed results derived from the Giovanni online analysis system; and c) visualizing results derived from other standard web services (e.g. OGC WMS). These implementations produce KMZ files that can be opened and visualized via a Google Earth (tm). Integrating A-Train data on Google Earth (tm) through ATDD (http://disc.gsfc.nasa.gov/atdd) affords users the ability to more efficiently discover, access, manipulate and analyze A-Train atmospheric data. The integration of Google Earth (tm) into the ATDD came with anticipated and unanticipated challenges, and solutions, insulated far beneath the easily obtainable ATDD Google Earth (tm) images and data downloads. In addition, some components of integration went rather smoothly. This presentation will discuss the challenges and non-challenges encountered and innovative solutions implemented to enable displaying NASA vertical and horizontal Earth science data within Google Earth (tm) technology. Findings discussed, include: - Interoperability between ATDD and Google Earth (tm) - Required enhancements to existing systems - Reuse of infused technology - Making the total greater than the some of the parts It is hoped that lessons learned and presented can be directly applied or extrapolated to better understanding and overcoming information technology infusion roadblocks.

  7. Astro-Venture: An Integrated Earth and Space Science Curriculum Supplement Focused on Astrobiology

    Microsoft Academic Search

    C. M. O'Guinn; K. L. Wilmoth; L. K. Coe

    2005-01-01

    Astro-Venture is an example of a NASA educational product that successfully integrates Earth and space science by engaging students in grades 5-8 in the search for and design of a planet with the necessary characteristics for human habitation. Students study the Earth to understand how it meets human needs for survival in the areas of astronomy, geology, biology and atmospheric

  8. Epithermal and thermal neutron response to rare earth doped fricke dosimeters

    E-print Network

    Groves, Kenneth Lee

    1970-01-01

    the linear gamma response of the undoped dosimeter, exposures were made to various energy neutron sources. Only at thermal ener gies or neutron spectrums which had large low energy contributions did the capture process play a large part and hence the rare... Fnicke dosimeters exposed to "Co gamma rays. . 14 Fig. 3. Absczbance versus dose from Eu doped Fricke dosimeters exposed to "Co gamma rays, . 15 Fig. 4. Absonbance versus dose for Dy doped Fricke dosimeters exposed to "Co gamma rays. . Fig. 5...

  9. Integrated assessment of packaging architectures in earth observing programs

    E-print Network

    Selva Valero, Daniel

    When designing Earth observation missions, it is essential to take into account the programmatic context. Considering individual missions as part of a whole enables overall program optimization, which may bring important ...

  10. 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 ~700um2 (including bend induced effective area reduction) at a bend diameter of 32cm from a 35?m 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 0.1dB/m while ensuring the higher order modes loss to be higher than 10dB/m at a wavelength of 1060nm. 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?m core fiber validating our simulation results. Fiber shows an excellent laser efficiency of ~81%and aM2 less than 1.1. PMID:25837082

  11. Towards mid-infrared fiber-lasers: rare earth ion doped, indium-containing, selenide bulk glasses and fiber

    NASA Astrophysics Data System (ADS)

    Sakr, H.; Tang, Z.; Furniss, D.; Sojka, L.; Moneim, N. A.; Barney, E.; Sujecki, S.; Benson, T. M.; Seddon, A. B.

    2014-02-01

    Chalcogenide glasses are promising materials for mid-infrared (IR) fiber lasers (i.e. 3 - 25 ?m wavelength range). These glasses exhibit low phonon energies, together with large refractive indices, rare earth (RE-) ion solubility and sufficient mechanical and chemical robustness. Optical quality of the fiber is key. Gallium is known to promote RE-ion solubility in chalcogenide glasses, probably forming a [Pr(III)] - Se - [Ga(III)] associated type complex. Here, indium is investigated as an alternative additive to gallium in Pr3+-doped Ge-As-Se chalcogenide glasses. Indium has the same outer electronic structure as gallium. Moreover, indium has the advantage of being heavier than gallium, potentially promoting a lower phonon-energy, local environment of the RE-dopant. Zero to ~2000 ppmw (nominal parts per million by weight) Pr3+- doped Ge-As-In-Se bulk glasses are prepared using the melt-quench method. ~500 ppmw Pr3+- doped Ge-As-In-Se, optically-clad fiber is realized via fiber-drawing of extruded fiberoptic preforms. Fiber absorption and emission spectra are collected and compared with those of the bulk glasses.

  12. 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 ?(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 ?(exci) ?= 331 nm (((7)F6 ? (5)D1). TL spectra show that Eu(3+) and Tb(3+) ions affect TL sensitivity. PMID:24616270

  13. Frequency dependence of Verdet constant of Bismuth-Doped Rare-Earth Iron Garnets for Magneto-Optic Sensor Applications

    NASA Astrophysics Data System (ADS)

    Shinn, Mannix; Tao, Rongjia; Wu, Dong Ho; Garzarella, Anthony

    2013-03-01

    There is growing interest in applying magneto-optic materials toward sensor applications. One of these applications is to exploit the Faraday Effect to measure magnetic fields. Bismuth-doped rare-earth iron garnets have proven to be highly sensitive Faraday rotators, but their frequency response and dynamic range to magnetic fields require further study. The Faraday Effect was studied in two samples of bismuth-doped rare-earth iron garnets grown in different conditions, and experiments were performed in a static field as well as in a RF field. Static magnetic fields up to 3 kG were used, and we found that the Faraday rotation became saturated at high fields, indicating that the field dependence follows the hyperbolic tangent function. We extracted each sample's Verdet constant from the Faraday rotation at low magnetic fields of 0.1 kG. These experiments were repeated using different laser probe beam wavelengths, ranging from 405 nm to 2000 nm. We measured the transmission coefficient and the Verdet constant for each sample for different probe beam wavelengths and for an external magnetic field at various frequencies. We will discuss the implication of our experimental results.

  14. Composition-driven structural phase transitions in rare-earth-doped BiFeO3 ceramics: a review.

    PubMed

    Arnold, Donna C

    2015-01-01

    Bismuth ferrite suffers from high leakage currents and the presence of a complex incommensurate spin cycloidal magnetic ordering, which has limited its commercial viability and has led researchers to investigate the functionality of doped BiFeO3 ceramics. In particular, the substitution of rare earths onto the Bi(3+) site of the perovskite lattice have been shown to lead to improved functional properties, including lower leakage currents and the suppression of the magnetic spin cycloid. There is particular interest in materials with compositions close to structural morphotropic phase boundaries, because these may lead to materials with enhanced electronic and magnetic properties analogous to the highly relevant PbZrO3- PbTiO3 solid solution. However, many contradictory crystal structures and physical behaviors are reported within the literature. To understand the structure-property relationships in these materials, it is vital that we first unravel the complex structural phase diagrams. We report here a comprehensive review of structural phase transitions in rare-earth-doped bismuth ferrite ceramics across the entire lanthanide series. We attempt to rationalize the literature in terms of the perovskite tool kit and propose an updated phase diagram based on an interpretation of the literature. PMID:25585391

  15. 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 been concluded to contain a nitrogen vacancy (V N) in its immediate structure. The nitrogen vacancy can appear in two symmetries, which has a profound impact on the luminescence and magnetic properties of the sample. The structure of the minority site has also been identified. For both sites, we give substantial evidence that the excitation efficiency of the red Eu emission is improved by the presence of donor-acceptor pairs in the vicinity of the Eu. Furthermore, when Mg was co-doped into GaN:Eu, additional incorporation environments were discovered that show high excitation efficiency at room temperature. These have been attributed to the coupling of Mg-H complexes to the majority Eu site. Electron beam irradiation, indirect and resonant (direct) laser excitation were found to modify these complexes, indicating that vibrational energy alone can trigger the migration of the H, while the presence of additional charges and excess energy controls the type of reconfiguration and the activation of non-radiative decay channels. We identify, experimentally, a two-step process in the dissociation of Mg-H complexes and propose, based on density functional theory, that the presence of minority carriers and the resulting charge states of complexes can also influence this process. In GaN:Er, we have given a more thorough overview of the optical and magneto-optical properties by extending to the 800nm excitation range and drastically improving the signal-to-noise ratio in the magnetic measurements, as well as applying a perpendicular magnetic field. This has allowed us to calculate g-factors for the parallel case, but revealed that the Zeeman interaction is not quite linear for perpendicular magnetic fields. We were able to assign crystal field numbers of mu = 3/2 to two crystal field levels. We have also given strong evidence that the strain in the sample, which results from lattice mismatch, enhances its magnetization, as seen through fluorescence line narrowing and asymmetry between the Zeeman transition intensities, under application of magnetic fields in anti-paralle

  16. Photoluminescence of the Eu-doped thin film heterojunction GaAs/SnO2 and rare-earth doping distribution

    NASA Astrophysics Data System (ADS)

    Bueno, C. F.; Scalvi, L. V. A.; Saeki, M. J.; Li, M. S.

    2015-03-01

    Tin dioxide (SnO2) thin films doped with Eu3+ are deposited by the sol-gel-dipcoating process on top of GaAs films, which is deposited by resistive evaporation on glass substrate. This heterojunction assembly presents luminescence from the rare-earth ion, unlike the SnO2 deposition directly on a glass substrate, where emissions from the Eu3+ transitions are absent. The Eu3+ transitions are clearly identified and are similar to the observation on SnO2 pressed powder (pellets), thermally treated at much higher temperatures. However, in the form of heterojunction films, the Eu emission comes along a broad band, located at higher energy compared to Eu3+ transitions, which is blue-shifted as the thermal annealing temperature increases. The size of nanocrystallites points toward quantum confinement or electron transfer between oxygen vacancies, originated from the disorder in the material, and trivalent rare-earth ions, which present acceptor-like character in this matrix. This electron transfer may relax for higher temperatures in the case of pellets, and the broad band is eliminated.

  17. [Effect of bivalent alkaline earth fluorides introduction on thermal stability and spectroscopic properties of Er3+/Tm3+ /Yb3+ co-doped oxyfluorogermanate glasses].

    PubMed

    Hu, Yue-bo; Zhang, Xin-na; Zhou, Da-li; Jiao, Qing; Wang, Rong-fei; Huang, Jin-feng; Long, Xiao-bo; Qiu, Jian-bei

    2012-01-01

    Transparent Er3+/Tm3+ /Yb3+ co-doped oxyfluorogermanate glasses alone containing MgF2, CaF2, SrF2 or BaF2 and nano-glass-ceramics only containing BaF2 were prepared. The thermal stabilities and the up-conversion emission properties of the samples were investigated. Analyses of absorbance spectra reveal that the UV cutoff band moves slightly to shortwave band with the doping bivalent cation mass increasing. The results show that the emission color can be adjusted by changing the alkaline earth cation species in the glass matrixes, especially as Mg2+ is concerned, and the emission intensity can increase notably by heating the glass containing alkaline-earth fluoride into glass ceramic containing alkaline-earth fluoride nanocrystals or increasing the content of bivalent alkaline earth fluorides. PMID:22497127

  18. Temperature dependent coercivity and magnetization of light rare-earth Nd doped permalloy thin films

    NASA Astrophysics Data System (ADS)

    Luo, Chen; Fu, Yu; Zhang, Dong; Yuan, Shijun; Zhai, Ya; Dong, Shuai; Zhai, Hongru

    2015-01-01

    The temperature dependence of the magnetic properties of Ni80Fe20 thin films with dilute Nd dopants has been studied. The effect of Nd dopants on the hysteresis loops of Nd-doped Ni80Fe20 thin films is small at room temperature but large at low temperature. The measurements show an interesting temperature dependence of the coercivity with different concentrations of Nd impurities, which might be related to the film structure. The temperature dependence of the saturation magnetization for Nd-doped Ni80Fe20 thin films is fitted by a theoretical expression of spin-wave excitation plus Stoner-type-like contribution, in which the spin-wave excitation plays a main role at low temperature. The spin-wave stiffness constant D evaluated from the fitting shows a strong doping concentration dependence.

  19. Exchange integrals in Mn- and Co-doped II-VI semiconductors

    NASA Astrophysics Data System (ADS)

    Savoyant, A.; D'Ambrosio, S.; Kuzian, R. O.; Daré, A. M.; Stepanov, A.

    2014-08-01

    Exchange integrals between nearest-neighbor (NN) transition metal ions in II-VI diluted magnetic semiconductors (DMSs) are calculated within a local superexchange model, which includes orbital-dependent transfer, on-site Coulomb repulsion and Hund's exchange between 3d electrons, and ligand field effects. This extended model gives a quantitative account for the available experimental data on the NN exchange constants in all II-VI DMS family (wurtzite and zinc-blende) doped by cobalt or manganese. As expected, all obtained exchange integrals are antiferromagnetic. Remarkably, the model input parameters are taken directly from the photoemission spectroscopy. We show that in the case of Co-doped compounds, as compared to Mn-doped ones, the exchange process has at least two salient features. The first one is that the electron transfer between NN Co2+3d orbitals strongly depends on their symmetry positions in the crystal lattice. The second one is related to a peculiar virtual process, involving empty and occupied Co2+3d orbitals, which leads to an additional ferromagnetic contribution to the exchange constant. We argue that our systematic study of the superexchange opens a pathway toward an understanding of other exchange mechanisms occurring in DMSs.

  20. Nano-arrays of optically addressable rare-earth-doped semiconductor quantum dots for quantum computing

    Microsoft Academic Search

    Aras Konjhodzic; Muhammed Aly; Deepka Chhabria; Zameer U. Hasan; M. Wu; Richard A. Register

    2004-01-01

    Results have been presented on isolating rare earth atoms in small numbers in semiconductor nanoparticles so as to use their organized arrays as hardware for quantum computing. We have tailored atomic states of rare earths, fabricated nanoparticles where these atomic systems are incorporated in small numbers and have patterned arrays of nano-holes on semi-conducting and polymer surfaces to encapsulate these

  1. Rare-Earth Doped LaF? Nanocrystals for Upconversion Fluorescence

    E-print Network

    Yi, Guang-Shun

    Upconversion fluorescent nanocrystals, Yb-Er, Yb-Ho and Yb-Tm co-doped LaF? were chemically synthesized. The average particle size was 4.4 nm with a narrow size distribution of ± 0.3 nm. Under the 980 nm NIR excitation, ...

  2. in "Properties, Processing and Applications of Glass and Rare Earth-Doped Glasses for Optical Fibres" ed. D. Hewak, INSPEC, The Institution of Electrical Engineers, London, UK, 1998.

    E-print Network

    Matthewson, M. John

    of Silica Fibres M. J. Matthewson May 1998 A INTRODUCTION The total length of silica optical fibre now optical fibres n a 2n i f Bt , (1) where B and n are fatigue parameters that are determinedin "Properties, Processing and Applications of Glass and Rare Earth-Doped Glasses for Optical

  3. 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.

  4. The optical antenna system design research on earth integrative network laser link in the future

    NASA Astrophysics Data System (ADS)

    Liu, Xianzhu; Fu, Qiang; He, Jingyi

    2014-11-01

    Earth integrated information network can be real-time acquisition, transmission and processing the spatial information with the carrier based on space platforms, such as geostationary satellites or in low-orbit satellites, stratospheric balloons or unmanned and manned aircraft, etc. It is an essential infrastructure for China to constructed earth integrated information network. Earth integrated information network can not only support the highly dynamic and the real-time transmission of broadband down to earth observation, but the reliable transmission of the ultra remote and the large delay up to the deep space exploration, as well as provide services for the significant application of the ocean voyage, emergency rescue, navigation and positioning, air transportation, aerospace measurement or control and other fields.Thus the earth integrated information network can expand the human science, culture and productive activities to the space, ocean and even deep space, so it is the global research focus. The network of the laser communication link is an important component and the mean of communication in the earth integrated information network. Optimize the structure and design the system of the optical antenna is considered one of the difficulty key technologies for the space laser communication link network. Therefore, this paper presents an optical antenna system that it can be used in space laser communication link network.The antenna system was consisted by the plurality mirrors stitched with the rotational paraboloid as a substrate. The optical system structure of the multi-mirror stitched was simulated and emulated by the light tools software. Cassegrain form to be used in a relay optical system. The structural parameters of the relay optical system was optimized and designed by the optical design software of zemax. The results of the optimal design and simulation or emulation indicated that the antenna system had a good optical performance and a certain reference value in engineering. It can provide effective technical support to realize interconnection of earth integrated laser link information network in the future.

  5. 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.

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

    NASA Astrophysics Data System (ADS)

    Li, Jiawei; Huo, Juntao; Law, Jiayan; Chang, Chuntao; Du, Juan; Man, Qikui; Wang, Xinmin; Li, Run-Wei

    2014-08-01

    The effects of heavy rare earth (RE) additions on the Curie temperature (TC) 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 TC in a large temperature range of 120 K without significantly decreasing the magnetic entropy change (?SM) and refrigerant capacity (RC) of the alloys. The observed values of ?SM and RC of these alloys compare favorably with those of recently reported Fe-based metallic glasses with enhanced RC compared to Gd5Ge1.9Si2Fe0.1. The tunable TC 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.

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

    SciTech Connect

    Abdinov, A. Sh., E-mail: abdinov-axmed@yandex.ru [Baku State University (Azerbaijan); Babayeva, R. F., E-mail: Babaeva-Rena@yandex.ru [Azerbaijan State Economic University (Azerbaijan); Amirova, S. I.; Rzayev, R. M. [Baku State University (Azerbaijan)] [Baku State University (Azerbaijan)

    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.

  8. Rare-earth ions doped heavy metal germanium tellurite glasses for fiber lighting in minimally invasive surgery.

    PubMed

    Yang, D L; Gong, H; Pun, E Y B; Zhao, X; Lin, H

    2010-08-30

    In Er(3+)/Yb(3+) codoped Na(2)O-ZnO-PbO-GeO(2)-TeO(2) (NZPGT) glass fiber, a clear and compact green upconversion amplified spontaneous emission (ASE) trace is observed, and the NZPGT glasses are proved to be a desirable candidate in fabricating low-phonon energy fiber. Intense green upconversion luminescence of Er(3+), balanced green and red upconversion emissions of Ho(3+), and dominant three-photon blue upconversion fluorescence of Tm(3+) have been represented. By varying the excitation power of 974 nm wavelength laser diode, a series of green and white fluorescences have been achieved in Tm(3+)/Er(3+)/Yb(3+) and Tm(3+)/Ho(3+)/Yb(3+) triply doped glass systems, respectively. These results reveal that high-intensity blue, green, and white upconversion ASE fluorescences, which can be adopted for lighting in minimally invasive photodynamic therapy and minimally invasive surgery, are reasonable to be expected in rare-earth doped NZPGT glass fibers. PMID:20940794

  9. 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.

  10. 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.

  11. Synthesis of doped rare earth manganate perovskite crystals using fused salt electrolysis

    SciTech Connect

    McCarroll, W.H. [Rider Univ., Lawrenceville, NJ (United States)] [Rider Univ., Lawrenceville, NJ (United States); Ramanujachary, K.V. [Rugers, State Univ. of New Jersey, Piscataway, NJ (United States)] [Rugers, State Univ. of New Jersey, Piscataway, NJ (United States); [Rowan College, Glassboro, NJ (United States); Greenblatt, M. [Rutgers, State Univ. of New Jersey, Piscataway, NJ (United States)] [Rutgers, State Univ. of New Jersey, Piscataway, NJ (United States)

    1997-05-01

    A facile method for the synthesis of doped lanthanum manganate crystals, suitable for the measurement of electrical and magnetic properties, is presented. Mixtures of sodium molybdate and molybdenum(VI) oxide are used as a solvent to which La{sub 2}O{sub 3}, MnCO{sub 3}, and SrMoCO{sub 4} are added as solutes which are then electrolyzed at 800-1040{degrees}C for varying lengths of time with Pt electrodes. Well-formed cubic crystals, with edge dimensions up to 1.5 mm, form at the anode. Magnetization measurements show a transition to the ferromagnetic state in the temperature range {approximately}250-320 K, depending on the amount of aliovalent doping at the La sites. An insulator-to-metal transition is also observed in the vicinity of the ferromagnetic ordering temperature.

  12. 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.

  13. Characterizing the purple Earth: Modelling the globally-integrated spectral variability of the Archean Earth

    E-print Network

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

    2013-01-01

    The 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 placed on 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 Ga, and its appearance has changed with time. Here, we have studied the Earth during the Archean eon, 3.0 Ga 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 used a radiative transfer model to simulate the visible and near-IR radiation reflected by our planet, taking into account several scenarios regarding the possible distribution of purple bacteria over continents an...

  14. A Hybrid Integrated Silicon Diode Array for Visible Earth-Horizon Sensing

    Microsoft Academic Search

    F. Bachner; R. Cohen; W. McGonagle; A. Foyt

    1974-01-01

    An earth-horizon sensing device which operates principally in the visible portion of the spectrum has been designed as a hybrid integrated circuit. The circuit was fabricated and tested for use in the LES-8\\/9 communications satellites as part of the system which maintains the satellites' orientation with respect to earth. The hybrid circuit consists of four silicon chips mounted on a

  15. Synthesis of Doped Rare Earth Manganate Perovskite Crystals Using Fused Salt Electrolysis

    Microsoft Academic Search

    W. H. McCarroll; K. V. Ramanujachary; M. Greenblatt

    1997-01-01

    A facile method for the synthesis of doped lanthanum manganate crystals, suitable for the measurement of electrical and magnetic properties, is presented. Mixtures of sodium molybdate and molybdenum(VI) oxide are used as a solvent to which La2O3, MnCO3, and SrMoCO4are added as solutes which are then electrolyzed at 800–1040°C for varying lengths of time with Pt electrodes. Well-formed cubic crystals,

  16. Addressing the Electrical Transport Behavior of Rare Earth Doped Multiferroic Bismuth Ferrite

    Microsoft Academic Search

    K. Pradhan; K. Roul

    Frequently observed deformation of P-E hysteresis loops of multiferroic BiFeO3 (BFO) and doped BFO by leakage currents hindered potential applications of BFO. Apart from the increased power consumption and heating due to leakage current, charge injection associated with the electrical transport properties (I-V) is also believed to be involved in accelerating fatigue as well as raising other reliability issues for

  17. 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.

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

    SciTech Connect

    Dargis, Rytis, E-mail: dargis@translucentinc.com; Clark, Andrew; Erdem Arkun, Fevzi [Translucent, Inc., 952 Commercial St., Palo Alto, California 94303 (United States); Grinys, Tomas; Tomasiunas, Rolandas [Institute of Applied Research, Vilnius University, Sauletekio al. 10, LT-10223 Vilnius (Lithuania); O'Hara, Andy; Demkov, Alexander A. [Department of Physics, The University of Texas at Austin, 2515 Speedway, C1600, Austin, Texas 78712 (United States)

    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.

  19. Integrated Earth Observation System Could Help Reduce Impacts of Natural Hazards

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    The development of a framework for an integrated Earth observation system is on a fast track, according to Conrad Lautenbacher, administrator for the U.S. National Oceanic and Atmospheric Administration, because of the impetus provided by a high-level summit this summer, and also because of existing Earth monitoring efforts that have laid much of the groundwork. Lautenbacher made his remarks on 22 October at a workshop on reducing natural disasters through improved Earth observations, held in Washington, D.C. The ministerial-level summit was on 31 July in Washington, D.C. (see Eos, 12 August).

  20. 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.

  1. 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

  2. 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 spatial resolution. Finally, formal quantitative integration would logically begin with employing accepted relationships between physical properties (e.g., there are widely used empirical relationships between Vp and density) and then proceed to producing integrated models that facilitate the search for anomalies. Our workshops and community interactions have shown that both raster (voxels) and vector (surfaces) 3D data structures would be involved if we are to produce integrated models that have all of the properties that the community desires. These interactions also quickly revealed a consensus that building such models can only be achieved through a highly integrated approach that takes advantage of all of the geological and geophysical constraints available. Conceptually, the modeling would begin with a voxel-based approach of building a highly-integrated 3-D model at Time=0 by deriving physical properties such as Vp, Vs, density, magnetic properties, electrical properties, anisotropy, attenuation (Q), temperature, etc. for volume elements that could take on several forms. Then, interfaces that represent features such as the Moho, major faults, crystalline basement surface beneath sedimentary basins, magmatic bodies, etc. would be inserted into the model in order to properly characterize the region geologically.

  3. 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. [Department of Applied Science, University of California Davis, Davis, California 95616 (United States); Reis, Signo T.; Brow, Richard K. [Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, Missouri 65409 (United States)

    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.

  4. Microhardness of silicon doped with isovalent or rare-earth impurities

    SciTech Connect

    Brinkevich, D.I. [Belarussian State Univ., Minsk (Belarus); Vabishchevich, S.A. [Novopolotsk Polytechnical Institute, Novopolotsk (Belarus)

    1994-05-01

    When large-diameter silicon ingots are used in the production of semiconductor devices, severe requirements are imposed for the mechanical strength of the wafers produced. A convenient parameter for evaluating the mechanical strength is microhardness. Below, the authors report on a study of the microhardness of Czochralski-grown and floating-zone-grown silicon (Cz-Si and FZ-Si, respectively) doped with Er, Dy, and Ge, and of Si{sub 1-x}Ge{sub x} (x = 0.01-0.14) alloys.

  5. Band-gap engineering for removing shallow traps in rare-earth Lu3Al5O12 garnet scintillators using Ga3+ doping

    NASA Astrophysics Data System (ADS)

    Fasoli, M.; Vedda, A.; Nikl, M.; Jiang, C.; Uberuaga, B. P.; Andersson, D. A.; McClellan, K. J.; Stanek, C. R.

    2011-08-01

    We employ a combination of first-principles calculations and optical characterization experiments to explain the mechanism by which Ga3+ doping prevents the trapping of free carriers due to shallow traps in RE3Al5O12 garnet scintillators (where RE represents a 3+ rare-earth cation). Specifically, we confirm that Ga3+ doping does not reduce the defect concentration (defect engineering), but rather leads to shifts in the valence and conduction bands such that the energy level of shallow defects is no longer in the forbidden gap where electrons can be trapped (band-gap engineering).

  6. Nanostructure magneto-optical thin films of rare earth (RE=Gd,Tb,Dy) doped cobalt spinel by sol-gel synthesis

    NASA Astrophysics Data System (ADS)

    Cheng, Fuxiang; Liao, Chunsheng; Kuang, Junfeng; Xu, Zhigang; Yan, Chunhua; Chen, Liangyao; Zhao, Haibin; Liu, Zhu

    1999-03-01

    Nanocrystalline CoFe1.9RE0.1O4 [rare earth (RE=Gd,Tb,Dy)] films have been prepared by the sol-gel route, and their polar magneto-optical (MO) Kerr rotation and ellipticity have been determined in the spectral range of 4000-8000 Å. The films are composed of nanometer grains with the spinel structure. RE doped cobalt spinel ferrites are found to have dramatic changes in magnetic and MO properties, with increases in their coercive force and enhancement of the MO rotation in the Tb3+ doped sample.

  7. Efficient dual-wavelength excitation of Tb3+ emission in rare-earth doped KYF4 cubic nanocrystals dispersed in silica sol-gel matrix

    NASA Astrophysics Data System (ADS)

    del-Castillo, J.; Yanes, A. C.; Santana-Alonso, A.; Méndez-Ramos, J.

    2014-11-01

    Energy transfer from Ce3+ to Tb3+ ions under UV excitation, giving rise to visible emissions, is investigated in sol-gel derived transparent nano-glass-ceramics containing cubic KYF4 nanocrystals, for different doping concentrations of rare-earth ions. Moreover, visible emissions of Tb3+ are also obtained under near-infrared excitation through energy transfer from Yb3+ ions by means of cooperative up-conversion processes. Thus, Ce3+-Tb3+-Yb3+ doped nano-glass-ceramics can be activated in a dual-wavelength mode yielding efficient blue-green emissions of particular interest in photovoltaic silicon solar cells and white-light emitting diodes.

  8. 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.

  9. Measuring and analyzing excitation-induced decoherence in rare-earth-doped optical materials

    NASA Astrophysics Data System (ADS)

    Thiel, C. W.; Macfarlane, R. M.; Sun, Y.; Böttger, T.; Sinclair, N.; Tittel, W.; Cone, R. L.

    2014-10-01

    A method is introduced for quantitatively analyzing photon echo decay measurements to characterize excitation-induced decoherence resulting from the phenomenon of instantaneous spectral diffusion. Detailed analysis is presented that allows fundamental material properties to be extracted that predict and describe excitation-induced decoherence for a broad range of measurements, applications and experimental conditions. Motivated by the need for a method that enables systematic studies of ultra-low decoherence systems and direct comparison of properties between optical materials, this approach employs simple techniques and analytical expressions that avoid the need for difficult to measure and often unknown material parameters or numerical simulations. This measurement and analysis approach is demonstrated for the 3H6 to 3H4 optical transition of three thulium-doped crystals, Tm3+:YAG, Tm3+:LiNbO3 and Tm3+:YGG, that are currently employed in quantum information and classical signal processing demonstrations where minimizing decoherence is essential to achieve high efficiencies and large signal bandwidths. These new results reveal more than two orders of magnitude variation in sensitivity to excitation-induced decoherence among the materials studied and establish that the Tm3+:YGG system offers the longest optical coherence lifetimes and the lowest levels of excitation-induced decoherence yet observed for any known thulium-doped material.

  10. a New Combustion Synthesis Technique for Rare Earth-Doped Iii-Nitride Luminescent Powders

    NASA Astrophysics Data System (ADS)

    Ramos, F. E.; Garcia, R.; Hirata, G. A.; Bosze, E. J.; McKittrick, J.

    A new low temperature method to produce ((RE)xGa1-x)2O3(1?x?0 and RE=Eu, Yb, Pr and Tm) powders with high purity, high chemical homogeneity and improved crystallinity has been developed. This procedure produces finely divided powders through an exothermic reaction between the precursors. The process starts with aqueous solutions of RE(NO3)3 and Ga(NO3)3 as the precursors and hydrazine as the (non-carbonaceous) fuel. The combustion reaction occurs when heating the precursors between 150 and 200°C in a closed vessel filled with an inert gas (Ar), which yields (RExGa1-x)2O3 directly. The preparation of RE-doped Ga2O3 powders was using a new combustion synthesis technique (Hydrazine / metal nitrate method). The preparation of Eu-doped GaN was using the ammonium hexafluoro-metal method. The powders were crystalline and high-purity as determined by XPS, EDS, SEM and XRD measurements.

  11. Spanning the spectrum of model complexity with a Grid-ENabled Integrated Earth system model (GENIE)

    Microsoft Academic Search

    T. Lenton

    2003-01-01

    We introduce GENIE, a Grid ENabled Integrated Earth system model for long-term and paleoclimate studies. The GENIE modelling framework will span an under-populated part of the spectrum of model complexity between EMICs and comprehensive models (CMs), by including variable spatial resolution of the components, and in some cases variable dimensionality. Traceability to CMs is being approached through a combination of

  12. 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…

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

    Microsoft Academic Search

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

    2012-01-01

    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

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

    Microsoft Academic Search

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

    2010-01-01

    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

  15. InP HEMT Integrated Circuits for Submillimeter Wave Radiometers in Earth Remote Sensing

    NASA Technical Reports Server (NTRS)

    Deal, William R.; Chattopadhyay, Goutam

    2012-01-01

    The operating frequency of InP integrated circuits has pushed well into the Submillimeter Wave frequency band, with amplification reported as high as 670 GHz. This paper provides an overview of current performance and potential application of InP HEMT to Submillimeter Wave radiometers for earth remote sensing.

  16. A hybrid integrated silicon diode array for visible earth-horizon sensing

    Microsoft Academic Search

    F. J. Bachner; R. A. Cohen; W. H. McGonagle; A. G. Foyt

    1974-01-01

    The present work describes fabrication and stress testing results for a hybrid, integrated earth-horizon sensor operating principally in the visible portion of the spectrum. The sensor consists of four silicon chips each containing a linear array of eight photodiode. The diodes are planar, n+ on p, shallow junction devices which use a channel stop to prevent surface inversion between diodes

  17. Earth

    NSDL National Science Digital Library

    This lithograph depicts a view of Earth taken from Apollo 10 during its journey to the Moon in May 1969. False-color satellite images showing chlorophyll concentration, sea surface temperature, topography, and ozone concentration are also featured. The images are accompanied by a brief description, some statistical facts, and a list of important dates in the history of Earth exploration.

  18. Towards the structure of rare earth luminescence centres - terbium doped aluminium nitride as an example system

    NASA Astrophysics Data System (ADS)

    Benz, Felix; Walther, Thomas; Strunk, Horst P.

    2013-11-01

    Sputter deposited terbium doped aluminium nitride layers were investigated with respect to the distribution and surroundings of the terbium luminescence ions. Semi-empirical calculations indicate that terbium forms complexes consisting of one aluminium vacancy surrounded by three oxygen ions on nitrogen lattice positions and one nitrogen ion that is bound to a terbium ion on a distorted aluminium lattice position. The crystal field splitting of the terbium ions indicate their surroundings to be not tetrahedral but, as anticipated from the determined complex, C3v. Complementary electron microscopic investigations show a random distribution of these complexes within the layer volume. The terbium ions cause a shape of the Tb M5,4 edge similar to the shapes in other ionic compounds like Tb2O3.

  19. 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

  20. Multicolor upconversion luminescence of rare-earth doped Y2CaZnO5 nanophosphors for white lighting-emitting diodes

    NASA Astrophysics Data System (ADS)

    Rajeswari, R.; Surendra Babu, S.; Jayasankar, C. K.

    2014-02-01

    Rare earth doped Y2CaZnO5 nanophosphors were synthesized via the citrate-gel combustion method. Transmission electron microscopy measurements reveal that the particles are distributed uniformly within the size range of 10-30 nm. The Er3+-doped Y2CaZnO5 nanophosphors show strong green upconversion luminescence, which is visible to the naked eye even at 20 mW excitation power of 980 nm diode laser. When these phosphors are codoped with Yb3+ ions, the emission changed to reddish color at higher Yb3+ ion concentrations. Moreover, these phosphors emitted bright white light luminescence when it is triply doped with Er3+/Tm 3+/Yb3+ ions, indicates Y2CaZnO5 nanophosphors are an ideal candidate for phosphor converted white light emitting diodes.

  1. Nanostructure magneto-optical thin films of rare earth (RE=Gd,Tb,Dy) doped cobalt spinel by sol-gel synthesis

    Microsoft Academic Search

    Fuxiang Cheng; Chunsheng Liao; Junfeng Kuang; Zhigang Xu; Chunhua Yan; Liangyao Chen; Haibin Zhao; Zhu Liu

    1999-01-01

    Nanocrystalline CoFe1.9RE0.1O4 [rare earth (RE=Gd,Tb,Dy)] films have been prepared by the sol-gel route, and their polar magneto-optical (MO) Kerr rotation and ellipticity have been determined in the spectral range of 4000-8000 Å. The films are composed of nanometer grains with the spinel structure. RE doped cobalt spinel ferrites are found to have dramatic changes in magnetic and MO properties, with

  2. Raman Spectroscopic Characterization of Rare Earth Ions Doped Bismuth-Based Glasses

    SciTech Connect

    Pop, L.; Culea, E.; Bosca, M. [Department of Physics, Technical University of Cluj-Napoca (Romania); Culea, M. [Faculty of Physics, Babes-Bolyai University of Cluj-Napoca (Romania)

    2007-04-23

    The xReO(1-x)[3Bi2O3{center_dot}PbO] glass systems with diferent rare earth ions (ReO = CeO2, Tb4O7) have been prepared and examined with the aim of determining their structural characteristics. Raman sprectroscopy and density measurements were used to characterize the samples. Raman spectroscopy data permitted to identify some of the structural units that built up the lead bismuthate vitreous network. Density data were used to calculate the Poisson's ratio in terms of the Makishima-Mackenzie model.

  3. 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???m were formed inside the capillaries for flowing of microfluidics. An FBG was inscribed in the tapered Co²?-doped fiber with waist diameter of ~70???m, 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. PMID:25361108

  4. 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. PMID:24245294

  5. 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 [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Graduate University of Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)] [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Graduate University of Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Wang, Yuansheng, E-mail: yswang@fjirsm.ac.cn [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Graduate University of Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)] [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Graduate University of Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

    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.

  6. Infrared-to-visible upconversion fluorescence spectroscopy in trivalent rare-earth-doped lead-magnesium-fluorophosphate glass

    NASA Astrophysics Data System (ADS)

    Bueno, Luciano A.; Gouveia-Neto, Artur da S.; Fonseca do Nascimento, Raphael; Arcanjo da Silva, Elias; do Nascimento, Valberes B.; Barbosa da Costa, Ernande

    2008-02-01

    There has recently been a great deal of interest in searching for new vitreous materials for application as hosts in infrared-to-visible light upconverters or optical amplifiers based upon rare-earth doped systems. Some of their many applications include: color displays, high density optical recording, biomedical diagnostics, infrared laser viewers and indicators, fiber lasers and amplifiers. Fluorophosphate-based glasses have recently emerged as auspicious candidates for such photonic devices applications. These glasses are advantageous because they present low nonlinear refractive indeces, better mechanical strength, chemical durability, and thermal stability than fluoride-based glasses and are suitable for developing low-loss, high strength, and low-cost optical fibers. It has recently been shown also that the fluorophosphate-based glass is an excellent candidate for high power lasers and broadband amplifiers in the eye-safe region around 1.5 ?m for applications in communication, medicine, and meteorology. The present work involves the investigation of optical transitions and upconversion fluorescence spectroscopy of trivalent lanthanide ions Er3+ and Tm3+ codoped with Yb3+ in P2O5-PbO-MgF2 glass, excited with near-infrared diode lasers. The dependence of the upconversion luminescence upon the Yb3+-concentration and diode laser power, and the upconversion excitation mechanisms involved are also investigated. The viability of using these glasses as host for practical applications in optical temperature sensors will also be presented.

  7. Enhancement of single particle rare earth doped NaYF4: Yb, Er emission with a gold shell

    NASA Astrophysics Data System (ADS)

    Li, Ling; Green, Kory; Hallen, Hans; Lim, Shuang Fang

    2015-01-01

    Upconversion of infrared light to visible light has important implications for bioimaging. However, the small absorption cross-section of rare earth dopants has limited the efficiency of these anti-Stokes nanomaterials. We present enhanced excitation absorption and single particle fluorescent emission of sodium yttrium fluoride, NaYF4: Yb, Er based upconverting nanoparticles coated with a gold nanoshell through surface plasmon resonance. The single gold-shell coated nanoparticles show enhanced absorption in the near infrared, enhanced total emission intensity, and increased green relative to red emission. We also show differences in enhancement between single and aggregated gold shell nanoparticles. The surface plasmon resonance of the gold-shell coated nanoparticle is shown to be dependent on the shell thickness. In contrast to other reported results, our single particle experimental observations are corroborated by finite element calculations that show where the green/red emission enhancement occurs, and what portion of the enhancement is due to electromagnetic effects. We find that the excitation enhancement and green/red emission ratio enhancement occurs at the corners and edges of the doped emissive core.

  8. 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: ctchang@nimte.ac.cn, E-mail: dujun@nimte.ac.cn; Du, Juan, E-mail: ctchang@nimte.ac.cn, E-mail: dujun@nimte.ac.cn; Man, Qikui; Wang, Xinmin; Li, Run-Wei [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Law, Jiayan [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg (Sweden)

    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 (?S{sub M}) and refrigerant capacity (RC) of the alloys. The observed values of ?S{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.

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

    SciTech Connect

    Grzyb, Tomasz, E-mail: tgrzyb@amu.edu.pl [Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, Pozna? 60-780 (Poland); Runowski, Marcin [Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, Pozna? 60-780 (Poland); Szczeszak, Agata [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, Pozna? 60-179 (Poland); Lis, Stefan [Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, Pozna? 60-780 (Poland)

    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.

  10. Optical amplification of Pr3+ -doped ZBLA channel waveguides for visible Laser emission.

    PubMed

    Olivier, M; Doualan, J-L; Camy, P; Lhermite, H; Pirasteh, P; Coulon, J N; Braud, A; Adam, J-L; Nazabal, V

    2012-10-22

    We report on the first observation of optical signal amplification in the visible range into praseodymium doped ZBLA glass channel waveguides obtained by ion exchange. Up to 30% signal amplification was obtained at 639 nm. This result shows the potential of rare earth doped fluoride glasses in the form of channel waveguides for integrated solid state visible laser sources. PMID:23187272

  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 programs available via either the Internet or CD (e.g., those distributed by P. Reiff, Rice University) that provide inquiry-based activities for students. There is great potential to share the connections of Earth and space science by using NASA developed education materials. The materials can be adapted for the classroom, after school programs, family outreach events, and summer science enrichment programs.

  12. 1 kW peak power passively Q-switched Nd(3+)-doped glass integrated waveguide laser.

    PubMed

    Charlet, B; Bastard, L; Broquin, J E

    2011-06-01

    Embedded optical sensors always require more compact, stable, and powerful laser sources. In this Letter, we present a fully integrated passively Q-switched laser, which has been realized by a Ag(+)/Na(+) ion exchange on a Nd(3+)-doped phosphate glass. A BDN-doped cellulose acetate thick film is deposited on the waveguide, acting as an upper cladding and providing a distributed saturable absorption. At ?=1054 nm, the device emits pulses of 1.3 ns FWHM with a repetition rate of 28 kHz. These performances, coupled with the 1 kW peak power, are promising for applications such as supercontinuum generation. PMID:21633424

  13. Earth

    NSDL National Science Digital Library

    This NASA (National Aeronautics and Space Administration) planet profile provides data and images of the planet Earth. These data include planet size, orbit facts, distance from the Sun, rotation and revolution times, temperature, atmospheric composition, density, surface materials and albedo. Images with descriptions show Earth features such as the Ross Ice Shelf in Antarctica, Simpson Desert in Australia, Mt. Etna in Sicily, the Cassiar Mountains in Canada, the Strait of Gibraltar, Mississippi River, Grand Canyon, Wadi Kufra Oasis in Libya, and Moon images such as Hadley Rille, Plum Crater, massifs and Moon rocks. These images were taken with the Galileo Spacecraft and by the Apollo missions.

  14. Energy Transfer Under Strong Pumping in High-Concentration Rare Earth Doped Laser Crystals

    NASA Astrophysics Data System (ADS)

    Knowles, David S.

    The weak interaction between isolated Er ions, and between Er and Pr ions, has been quantitatively measured in the host crystal BaY_2F _8. Fluorescent decay data from samples doped with 1%-100% Er and 0.05%-0.5% Pr show the decay rate is linearly proportional to the acceptor (Pr) concentration for all samples, and linearly proportional to the donor (Er) concentration for 5% Er or less, as predicted by the standard dipole-dipole coupling model. For Er concentrations greater than 20%, the decay has a much stronger dependence on the Er concentration, indicative of a strong short range coupling mechanism (higher order multipole or superexchange) operating between nearest neighbor ions. The dipole-dipole interaction strengths for Er-Er and Er-Pr transfer have been measured for the ^4{rm I }_{13/2}, ^4 {rm I}_{11/2}, and ^4{rm F}_{9/2 }<=vels, and the exciton diffusion rate is calculated as a function of the Er concentration. The upconversion interaction rate between excited Er ions has also been determined for 5%-100% Er:BaY _2F_8. The results show behavior similar to previous measurements of upconversion in Er:LiYF_4: the ^4 {rm I}_{11/2} upconversion strength increases with Er concentration, and the ^4{rm I}_{13/2} upconversion strength saturates at roughly 20% Er. The measured ^4{rm I} _{11/2} upconversion strengths have the same Er dependence as the Er-Pr transfer, indicating that the increase at high concentrations is due to the same short range interaction mechanism. The ^4 {rm I}_{13/2} saturation is thought to be due to a bottleneck for Er-Er transfer due to the poor overlap of the Er ^4{ rm I}_{13/2} emission and excited state absorption. The ratio of ^4 {rm I}_{13/2} to ^4{rm I}_{11/2 } upconversion strengths is greater in BaY _2F_8, indicating this may be a better host for an upconversion laser. Attempts to confirm this by directly measuring the laser slope efficiency for different crystals in the same laser configuration, indicate that BaY_2F_8 may be a better host, but the maximum slope efficiency was much less than expected for efficient recycling of energy by ^4{rm I}_ {13/2} upconversion. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.).

  15. Fundamentals of laser cooling of rare-earth-ion doped solids and its enhancement using nanopowders

    NASA Astrophysics Data System (ADS)

    Ruan, Xiulin

    The Fermi golden rule is applied as the primary theory for laser cooling of solids, by recognizing that the absorption is a photon-induced, phonon-assisted, electronic transition. The limiting factors are identified as the coupling and population of the energy carriers (photon, electron, and phonon), which include the photon-electron coupling, electron-phonon coupling, ion-dopant concentration, phonon density of states, and the photon population. The photon-electron and electron-vibration coupling rates for ion-doped materials are calculated using ab initio methods for the first time. Using the calculated first-principle wavefunctions, the electric transition dipole moment between the ground and excited states is determined by its definition. The electron-phonon coupling is calculated by taking into account the modification of the electronic wavefunction in response to the nuclei motion, and the modifications of the vibrational modes before and after the transition. This ab initio approach does not require any fitting to experiment, providing a theoretical foundation for the optimal selection of laser cooling materials (both dopant and host). Nanostructure is proposed for the first time to enhance laser cooling performance, through the optimization of carrier populations using nanopowders. The concept of optimum dopant concentration is established and determined using the energy transfer theory, and is found to be larger than that currently used. The phonon density of states of nanopowders, calculated using molecular dynamics simulations, exhibits broadened modes, and extended tails at low and high frequencies. This is advantageous over the bulk material since more phonon modes are available in the desired range. The pumping field energy is calculated by solving the Maxwell equations in random nanopowder media. Photons are multiply scattered and do not propagate through the medium, and large field enhancement is observed. This leads to the trapping of more photons in nanopowder media, compared to the bulk material, implying more efficient absorption and cooling performance. Due to these enhancement effects, thermal predictions show that nanopowders can be cooled to the cryogenic temperature range, for the first time.

  16. Excitation and luminescence of rare earth-doped lead phosphate glasses

    NASA Astrophysics Data System (ADS)

    Pisarska, J.; So?tys, M.; ?ur, L.; Pisarski, W. A.; Jayasankar, C. K.

    2014-09-01

    Excitation and luminescence properties of Eu3+, Tb3+ and Er3+ ions in lead phosphate glasses have been studied. From excitation spectra of Eu3+ ions, the electron-phonon coupling strength and phonon energy of the glass host were calculated and compared to that obtained by Raman spectroscopy. Main intense and long-lived luminescence bands are related to the 5D0-7F2 (red) transition of Eu3+, the 5D4-7F5 (green) transition of Tb3+ and the 4I13/2-4I15/2 (near-infrared) transition of Er3+. The critical transfer distances, the donor-acceptor interaction parameters and the energy transfer probabilities were calculated using the fitting of the luminescence decay curves from 5D0 (Eu3+), 5D4 (Tb3+) and 4I13/2 (Er3+) excited states. The energy transfer probabilities for Eu3+ (5D0), Tb3+ (5D4) and Er3+ (4I13/2) are relatively small, which indicates low self-quenching luminescence of rare earth ions in lead phosphate glasses.

  17. Modeling the Integrated Water Cycle in an Earth System Model (Invited)

    NASA Astrophysics Data System (ADS)

    Leung, L.; Li, H.; Voisin, N.; Hejazi, M. I.; Huang, M.; Liu, L.; Tesfa, T. K.

    2013-12-01

    Human systems have significantly perturbed the water cycle through water management and water use. As climate and the environment change in the future, human systems may adapt to cope with and mitigate the changes so dynamically representing them in Earth system models will advance long-term prediction of water cycle changes. As part of the Community Earth System Model (CESM), the Community Land Model (CLM) includes sophisticated representations of biophysics, soil hydrology, and biogeochemistry, but human systems of water are largely ignored. As a step towards modeling the fully integrated water cycle, a water management model has been developed for coupling with CLM and a river routing model. The water management model uses generic operating rules for multi-purpose reservoirs. The river routing model adopts a simple physically based framework to represent river routing from hillslopes to the main channels and through the channel network. The models have been tested over large river basins in the Pacific Northwest and Midwest, with ongoing progress towards global implementation. This presentation will introduce the overall modeling framework, highlight selected modeling results, and discuss ongoing research to couple the models with integrated assessment models to dynamically simulate human decisions and human systems in Integrated Earth System Models.

  18. PL and EL characteristics in Bi- and rare earth-co-doped (La1-XGaX)2O3 phosphor thin films prepared by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Miyata, Toshihiro; Nishi, Yuki; Minami, Tadatsugu

    2011-12-01

    Multicolor photoluminescence (PL) and electroluminescence (EL) were observed from newly developed Bi- and rare earth (RE)-co-doped (La1-XGaX)2O3 ((La1-XGaX)2O3:Bi,RE) phosphor thin films. (La1-XGaX)2O3:Bi,RE phosphor thin films were prepared by varying the Ga content (Ga/(La+Ga) atomic ratio) or the co-doped RE content (RE/(RE+La+Ga) atomic ratio) under co-doping Bi at a constant content (Bi/(Bi+La+Ga) atomic ratio) of 3 at.% using a combinatorial r.f. magnetron sputtering deposition method. High PL intensity was obtained in postannealed (La0.9Ga0.1)2O3:Bi,RE phosphor thin films prepared with a Ga content around 10 at.%; TFEL devices fabricated using the phosphor thin films exhibited high luminance. The obtained luminance intensities in EL and PL in the phosphor thin films prepared with various contents of co-doped RE, such as Dy, Er, Eu, Tb and Tm changed considerably as the kind and content of RE were varied. Color changes from blue and blue-green to various colors in PL and EL emissions, respectively, were obtained in postannealed (La0.9Ga0.1)2O3:Bi,RE phosphor thin films, i.e., films prepared by co-doping Bi at a constant content with various REs at varying levels of content. All the observed emission peaks in PL and EL from (La0.9Ga0.1)2O3:Bi,RE phosphor thin films were assigned to either the broad emission originating from the transition in Bi3+ or the visible emission peaks originating from the transition in the co-doped trivalent RE ion.

  19. RESIF: a French Integrated Antenna for the Observation of Earth Deformation (Invited)

    NASA Astrophysics Data System (ADS)

    Pedersen, H.

    2009-12-01

    The densification of the networks and a strong integration of seismic, geodetic and spatial observations will remain a major challenge over the decade to come. In Europe, the EPOS (European Plate Observing System) project will carry this development forward as it is intended to be a major future research infrastructure in Europe which integrates geophysical observations into a single comprehensive solid earth monitoring system. This integrated European structure is made possible only through the strong effort of open data access that has been pushed forward during the last two decades, in particular through the ORFEUS data center and several European projects, such as NERIES. Open data access is in fact the only possible way forward to obtain an integrated geophysical research structure, as the political landscape in Europe remains complex where issues related to civil protection and natural disasters remain within the competence of each nation. RESIF (Réseau Sismologique Français) is built with the intention of being a major French contribution in the development of EPOS. The RESIF infrastructure will be an integrated antenna to observe solid Earth deformation at all time scales. The project therefore includes seismic observations as well as geodetic (GPS, gravimetry) and spatial observations, in partnership between the French CNRS-INSU and all the major national institutes involved in studying and monitoring the earth. Through this project we intend to completely renovate the French permanent and temporary geophysical equipment and the associated data access. In metropolitan France, the present seismic broadband and short period regional seismic networks will be merged and extended to obtain a regular grid of 50 broadband (10Hz-120s) stations and 120 intermediate period (30Hz-40s) stations with higher station density in the seismically most active areas. The already extensive French accelerometric and GPS networks will also integrate RESIF. The total number of permanent earth-based systems in metropolitan France will be approximately 500. The portable seismic, GPS and gravimeter equipment will be strongly increased to obtain a pool of approximately 350 instruments (GPS, intermediate band and broadband seismic). Discussions with the French spatial agency (CNES) will define the priority actions to be taken over the next few years. They are likely to include an improved strategy and data share to increase precision in positioning measurements as well as access to observations of seismic waves and earthquake damage patterns even after minor seismic events. Data from the permanent RESIF antenna will be freely available via standard request tools in real-time or near real-time via a unified French data distribution system and integrated into European and Worldwide data exchange systems. Data from field experiments using the RESIF portable equipment will also be freely available, with a standard distribution delays.

  20. Facile fabrication and photoluminescence properties of rare-earth-doped Gd?O? hollow spheres via a sacrificial template method.

    PubMed

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

    2013-08-21

    Rare-earth-doped gadolinium oxide (Gd?O?) 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 Gd?O? spheres with a mean particle size of about 2.3 ?m 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 Gd?O? 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, Gd?O?:Ln³? (Ln³? = Yb³?/Er³?, Yb³?/Tm³? and Yb³?/Ho³?) exhibit characteristic up-conversion (UC) emissions of red (Er³?, ²H11/2, ?S3/2, ?F9/2 ? ?I15/2), blue (Tm³?, ¹G? ? ³H?) and green (Ho³?, ?F?, ?S? ? ?I?), 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. PMID:23801272

  1. Earth

    E-print Network

    unknown authors

    As in his original cosmology proposal 1,2 and in subsequent writings in its defence, 3,4 so also in New vistas of space-time rebut the critics, 5 Dr Humphreys makes sweeping physical claims without backing them up with the simple mathematical calculations which would demonstrate their truth or falsity. It is straightforward, using only undergraduate-level differential calculus, to show that Humphreys’ claim of a ‘timeless zone ’ in the Klein metric is false. In order for a ‘timeless zone ’ to exist, there must be a region of spacetime within which there are no spacetime trajectories which have the property ds 2> 0. However, it is easy to verify that every comoving clock in Humphreys ’ bounded matter sphere cosmology traverses a timelike trajectory (ds 2> 0), even in the region of (?,?) space which Humphreys alleges is ‘timeless. ’ Consider, for example, the trajectory of the Earth, which Humphreys hypothesizes is at the center of the matter sphere. The Earth’s spatial trajectory in Schwarzschild coordinates is given by d?

  2. Coupling earth system and integrated assessment models: the problem of steady state

    NASA Astrophysics Data System (ADS)

    Bond-Lamberty, B.; Calvin, K.; Jones, A. D.; Mao, J.; Patel, P.; Shi, X.; Thomson, A.; Thornton, P.; Zhou, Y.

    2014-02-01

    Human activities are significantly altering biogeochemical cycles at the global scale, posing a significant problem for earth system models (ESMs), which may incorporate static land-use change inputs but do not actively simulate policy or economic forces. One option to address this problem is to couple an ESM with an economically oriented integrated assessment model. Here we have implemented and tested a coupling mechanism between the carbon cycles of an ESM (CESM, the Community Earth System Model) and an integrated assessment (GCAM) model, examining the best proxy variables to share between the models, and quantifying our ability to distinguish climate- and land-use-driven flux changes. The net primary production and heterotrophic respiration outputs of the Community Land Model (CLM), the land component of CESM, were found to be the most robust proxy variables by which to manipulate GCAM's assumptions of long-term ecosystem steady state carbon, with short-term forest production strongly correlated with long-term biomass changes in climate-change model runs. Carbon-cycle effects of anthropogenic land-use change are short-term and spatially limited relative to widely distributed climate effects, and as a result we were able to distinguish these effects successfully in the model coupling, passing only the latter to GCAM. By allowing climate effects from a full earth system model to dynamically modulate the economic and policy decisions of an integrated assessment model, this work provides a foundation for linking these models in a robust and flexible framework capable of examining two-way interactions between human and earth system processes.

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

    SciTech Connect

    Fujii, Yuka; Suto, Yasushi [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Turner, Edwin L., E-mail: yuka.fujii@utap.phys.s.u-tokyo.ac.jp [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    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.

  4. 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…

  5. Investigation of the deposition of porous layers by the MCVD method for the preparation of rare-earth doped cores of optical fibres

    NASA Astrophysics Data System (ADS)

    Pal, M.; Sen, R.; Paul, M. C.; Bhadra, S. K.; Chatterjee, S.; Ghosal, D.; Dasgupta, K.

    2005-10-01

    Investigation was carried out on core layer deposition by modified chemical vapour deposition (MCVD) process to fabricate rare earth (RE) doped preforms and fibres. The solution doping technique was adopted for incorporation of the RE and codopant such as Al 2O 3 into the core. The deposited cores composed of GeO 2/P 2O 5/SiO 2 glasses with GeO 2 level in the range of 3-15 mol% and P 2O 5 up to 5 mol%. The soot layer was deposited inside the substrate tube both by forward and backward deposition methods. This basic difference in the process between the two modes of deposition produced significant variation in the RE incorporation, numerical aperture as well as core-clad dimensions, all of which contribute to the end fibre performance. The backward deposition method provided greater flexibility and control over the RE incorporation.

  6. Parametrization of Crystal Field Splittings of the 7Fj Levels in Eu3+ Doped Tetragonal Rare Earth Oxyhydroxides, REOOH :Eu 3+ (RE = Y and Lu)

    NASA Astrophysics Data System (ADS)

    Hölsä, Jorma

    1990-02-01

    The luminescence spectra of europium (3 + ) doped rare earth oxyhydroxides, REOOH :Eu3 + (RE = Y and Lu), were studied and analyzed at 77 and 300 K under UV and dye laser excitation. The observed 7F0_4 level schemes were simulated with the aid of the phenomenological crystal field theory. The descending symmetry method from C2v to Cs symmetry was used in the simulation. Good results were obtained with Cs symmetry simulation which yielded r.m.s. deviations of 6 and 7 cm -1 between the calculated and experimental 7F0_4 level schemes for YOOH:Eu3 + and LUOOH:EU3+, respectively. The C2v simulation was found inadequate to describe the experimental energy level schemes. The even rank crystal field parameters vary only slightly as a function of the host. Comparison with the corresponding values obtained for the monoclinic form of the Eu3 + doped RE oxyhydroxides reveals significant differences.

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

    SciTech Connect

    Gomez-Leal, I.; Selsis, F. [Univ. Bordeaux, LAB, UMR 5804, F-33270 Floirac (France); Palle, E., E-mail: gomezleal@obs.u-bordeaux1.fr, E-mail: selsis@obs.u-bordeaux1.fr, E-mail: epalle@iac.es [Instituto de Astrofisica de Canarias, Via Lactea s/n, La Laguna E-38205, Tenerife (Spain)

    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.

  8. 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.

  9. Variability of Water and Oxygen Absorption Bands in the Disk-Integrated Spectra of the Earth

    E-print Network

    Fujii, Yuka; Suto, Yasushi

    2013-01-01

    We study the variability of major atmospheric absorption features in the disk-integrated spectra of the Earth with future application to Earth-analogs in mind, concentrating on the diurnal timescale. We first analyze observations of the Earth provided by the EPOXI mission, and find 5-20% fractional variation of the absorption depths of H2O and O2 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 ...

  10. Advancing Coupled Human-Earth System Models: The Integrated Ecosystem Demography Model (iED) Project

    NASA Astrophysics Data System (ADS)

    Hurtt, G. C.; Chini, L. P.; Clarke, L.; Calvin, K. V.; Chambers, J. Q.; Dubayah, R.; Dolan, K.; Edmonds, J. A.; Fisk, J. P.; Flanagan, S.; Frolking, S.; Janetos, A. C.; LePage, Y.; Morton, D. C.; Patel, P.; Rourke, O.; Sahajpal, R.; Thomson, A. M.; Wise, M.; Ying, Q.

    2012-12-01

    Recent studies with integrated assessment models, models linking human and natural systems at a global scale, highlight the importance of terrestrial systems in climate stabilization efforts. Here we introduce a new modeling framework iED, designed to link advanced remote sensing data (active and passive.), height-structured terrestrial ecosystem dynamics (ED), gridded land-use change projections (GLM), and integrated assessment modeling (GCAM) into a single coupled modeling framework with unprecedented spatial resolution and process-level detail. Our research aims to reduce uncertainties associated with forest modeling within integrated assessments, and to quantify the impacts of climate change on forest growth, mortality, and productivity for integrated assessments of terrestrial carbon management. iED is being used to address key science questions including: (1) What are the opportunities for land-use strategies such as afforestation or woody bioenergy crop production to contribute to stabilization of atmospheric CO2 concentrations? (2) How could potentially altered disturbance rates from tropical cyclones and Amazonian fires affect vegetation, carbon stocks and fluxes, and the development of climate change mitigation strategies? (3) What are the linked remote sensing/ecosystem modeling requirements for improving integrated assessments of climate mitigation strategies? With its strong connections to data and conceptual linkages to other models in development, iED is also designed to inform the next generation of remote sensing and integrated Earth system modeling efforts.

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

    NASA Astrophysics Data System (ADS)

    ?ulubrk, Sanja; Anti?, Željka; Marinovi?-Cincovi?, Milena; Ahrenkiel, Phillip S.; Drami?anin, 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+).

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

    SciTech Connect

    Ferrer, Sebastian [Dpto. de Matematica Aplicada, Universidad de Murcia, ES-30071 Espinardo, Murcia (Spain); Lara, Martin, E-mail: sferrer@um.e, E-mail: mlara@roa.e [Real Observatorio de la Armada, ES-11110 San Fernando, Cadiz (Spain)

    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.

  13. Proton solubility for La 2Zr 2O 7 with a pyrochlore structure doped with a series of alkaline-earth ions

    Microsoft Academic Search

    Takahisa Omata; Katsuhiko Ikeda; Ryoji Tokashiki; Shinya Otsuka-Yao-Matsuo

    2004-01-01

    Alkaline-earth ion doped La2Zr2O7 samples with a pyrochlore structure, i.e., (La2?xMx)Zr2O7?? and La2(Zr2?xMx)O7?? (M=Mg, Ca, Sr and Ba), were prepared by conventional ceramic methods. The quantity of protons dissolved in the crystal was evaluated by evolved H2O gas, which was detected by a quadrupole mass spectrometer. The relationship between the proton solubility of the La2Zr2O7-based high temperature proton conductor and

  14. 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.

  15. Prospects for projecting the impact of Earth system processes on Integrated Assessment

    NASA Astrophysics Data System (ADS)

    Collins, W.; Edmonds, J. A.; Thornton, P. E.; Craig, A.; Hurtt, G. C.; Janetos, A. C.; Jones, A.; Koven, C. D.; Riley, W. J.; Truesdale, J.

    2012-12-01

    We discuss the prospects for advancing the quantitative exploration of climate mitigation strategies using the integrated Earth System Model (iESM). The iESM leverages existing investments by DOE in community simulation capabilities including the Community Earth System Model (CESM) together with the Global Change Assessment Model (GCAM) and the Global Land-use Model (GLM). GCAM and GLM are the foundation for one of the Representative Concentration Pathways (RCPs) evaluated in the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC). The distinguishing features of iESM are the incorporation of integrated assessment capabilities into a full ESM and the provision for two-way interactions between the energy sector and climate change. Initial experiments using this new modeling system have demonstrated the need to revisit the conceptual design of the RCP scenarios [Moss, et al., 2010]. The iESM team has shown that feedbacks from climate change to the energy sector, an important class of interactions omitted from the current IPCC scenarios, can significantly alter the future allocation of land for energy and food production. Because human and biogeophysical Earth systems are closely coupled in the iESM, it is now possible to rapidly explore climate implications of new scenarios for future assessments and likewise to quantify the effects of improved treatments of major climatic processes on those scenarios. We discuss the progress towards significantly enhanced treatments of aerosols, carbon cycles, and methane feedbacks in CESM. We conclude with the potential applications of these capabilities in integrated assessment on decadal to centennial timescales using iESM.

  16. A space system integrating earth observation and mobile communications for equatorial remote areas

    NASA Astrophysics Data System (ADS)

    Ceballos, Decio C.

    1993-10-01

    The integration of two constellations of light and low-cost satellites, the Equatorial Communications (ECO) system and a polar orbit system for World Observation and Monitoring (WOM), is proposed. The WOM involves eight satellites and portable data reception and processing equipment. Onboard data compression enables UHF transmission of earth observation data. A system for global coverage with a temporal result of two passes per day is proposed. The ECO involves eight satellites in an equatorial constellation at 2000 mm. This system can supply low-orbit communications for equatorial countries and assist in the daily monitoring of ecologically protected areas.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

    Agilandeshwari, R.; Muthu, K.; Meenatchi, V.; Meena, K.; Rajasekar, M.; Aditya Prasad, A.; Meenakshisundaram, SP.

    2015-02-01

    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.

  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. Visible light responsive sulfated rare earth doped TiO(2)@fumed SiO(2) composites with mesoporosity: enhanced photocatalytic activity for methyl orange degradation.

    PubMed

    Zhan, Changchao; Chen, Feng; Yang, Jintao; Dai, Daoxing; Cao, Xiaohua; Zhong, Mingqiang

    2014-02-28

    Visible light (VL) responsive mesoporous sulfated rare earth ions (Nd(3+), La(3+), Y(3+)) incorporated TiO2@fumed SiO2 photocatalysts were prepared by sol-gel method with P123 (EO20PO70EO20) as a template. The resultant samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption measurements (BET), UV-vis diffuse reflectance spectroscopy, photoluminescence (PL) spectra, Fourier transform infrared spectroscopy (FTIR) and thermal analyses (TG-DTA). In comparison with nondoped sample, RE-doped samples showed not only an increase in the surface areas and pore volumes, but also an inhibition of titania phase transition from anatase to rutile. Photo-degradation results revealed that RE-doped samples could greatly improve the photocatalytic activity, and the experimental degradation rates of methyl orange (MO) were higher than that catalyzed by undoped samples and Degussa P-25, obeyed the order of Nd(3+)>La(3+)>Y(3+). Nd-doped sample expressed the highest photoactivity and the optimal dosage was 0.25mol%, which resulted in MO degradation rates of 99.8% and 90.05% irradiation under UV for 60min and VL (?>400nm) for 40h, respectively. The enhanced photocatalytic activity could be attributed to the higher specific area, good crystallinity, strong VL absorption and effective separation of photogenerated electron-hole pairs in the catalyst. PMID:24418494

  1. 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

  2. From LACIE to GEOGLAM: Integrating Earth Observations into Operational Agricultural Monitoring Systems

    NASA Astrophysics Data System (ADS)

    Becker-Reshef, I.; Justice, C. O.

    2012-12-01

    Earth observation data, owing to their synoptic, timely and repetitive coverage, have long been recognized as an indispensible tool for agricultural monitoring at local to global scales. Research and development over the past several decades in the field of agricultural remote sensing has led to considerable capacity for crop monitoring within the current operational monitoring systems. These systems are relied upon nationally and internationally to provide crop outlooks and production forecasts as the growing season progresses. This talk will discuss the legacy and current state of operational agricultural monitoring using earth observations. In the US, the National Aeronautics and Space Administration (NASA) and the US Department of Agriculture (USDA) have been collaborating to monitor global agriculture from space since the 1970s. In 1974, the USDA, NASA and National Oceanic and Atmospheric Administration (NOAA) initiated the Large Area Crop Inventory Experiment (LACIE) which demonstrated that earth observations could provide vital information on crop production, with unprecedented accuracy and timeliness, prior to harvest. This experiment spurred many agencies and researchers around the world to further develop and evaluate remote sensing technologies for timely, large area, crop monitoring. The USDA and NASA continue to closely collaborate. More recently they jointly initiated the Global Agricultural Monitoring Project (GLAM) to enhance the agricultural monitoring and the crop-production estimation capabilities of the USDA Foreign Agricultural Service by using the new generation of NASA satellite observations including from MODIS and the Visible Infrared Imaging Radiometer Suite (VIIRS) instruments. Internationally, in response to the growing calls for improved agricultural information, the Group on Earth Observations (partnership of governments and international organizations) developed the Global Agricultural Monitoring (GEOGLAM) initiative which was adopted by the G20 as part of the action plan on food price volatility and agriculture. The goal of GEOGLAM is to enhance agricultural production estimates through leveraging advances in the research domain and in satellite technologies, and integrating these into the existing operational monitoring systems.

  3. 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.

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

    SciTech Connect

    Mohanta, Antaryami; Jang, Der-Jun, E-mail: djjang@mail.nsysu.edu.tw; Wang, Ming-Sung; Tu, L. W. [Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China)

    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.

  5. 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 suitable for probing, manipulating, sculpting, and sensing at single digit nanoscale. PMID:21534601

  6. Discovery, Integration, and Analysis (DIA) Engine for Ontologically Registered Earth Science Data

    NASA Astrophysics Data System (ADS)

    Sinha, A.; Malik, Z.; Rezgui, A.; Dalton, A.; Lin, K.

    2006-12-01

    A newly developed DIA engine within the NSF supported GEON program utilizes an ontologic cyberinfrastructure framework for discovery, integration, and analysis of earth science data. Data discovery, is commonly challenging because of the use of personalized acronyms, notations, conventions, etc., but can be simplified through ontologic registration. Data integration enables users to extract new information, called data products, by jointly considering and correlating several ontologically registered data sets. We have developed ontology packages as well as accessed ontologies such as SWEET, which provide concepts, concept taxonomies, relationships between concepts, and properties, as an initial step towards the development of complete heavyweight ontologies (with axioms and constraints) for earth science. The primary objective is to allow researchers to associate ontology to their data, so that a unique and definite meaning is associated with each data item. This facilitates data discovery and integration by relating data items with similar semantics across various repositories. The DIA engine provides a Web accessible graphical user interface (GUI) comprising of map services and query menus. Users can specify a "geological region of interest" by making selections on geologic maps which are part of the GUI. Moreover, interactive menus enable filtering, discovery and integration of data (geospatial as well as aspatial), using many tools, including those developed by the community. We support the Web services technology to share these tools since web services hide the tool implementation details and only provide the required invocation details (input/output parameters, etc.). Thus, geoscientists can build tools that access ontologically registered data and provide invocation details publicly. Therefore, any tool that is developed as a Web service can be plugged in the DIA engine. The DIA engine supports dynamic data product creation which requires "on-the-fly" discovery and integration of different ontologic data classes. The integration can either occur between the "same" ontologic class or across "different" ontologic classes. We also provide the capability to track all stages in the development of products, so other users can readily accept data products and may proceed into a data analysis phase (e.g., to verify hypothesis) . The development of DIA engine is guided by generating data products that can be analyzed to evaluate scientific hypotheses, such as "Do A-type plutons in Virginia mark the trace of a Neoproterozoic hot- spot?"

  7. Spanning the spectrum of model complexity with a Grid-ENabled Integrated Earth system model (GENIE)

    NASA Astrophysics Data System (ADS)

    Lenton, T.; Genie Team

    2003-04-01

    We introduce GENIE, a Grid ENabled Integrated Earth system model for long-term and paleoclimate studies. The GENIE modelling framework will span an under-populated part of the spectrum of model complexity between EMICs and comprehensive models (CMs), by including variable spatial resolution of the components, and in some cases variable dimensionality. Traceability to CMs is being approached through a combination of using components that are reduced versions of those in CMs (e.g. the land surface), basing components on the same physics but with fast processes parameterised (e.g. a frictional geostrophic ocean), and comparison with CM results at similar spatial resolution. The prototype GENIE-Trainer (also known as C-GOLDSTEIN) comprises a 3-D frictional geostrophic ocean, a 2-D energy moisture balance atmosphere (EMBM) and a sea-ice model. 4000 year integrations can be performed in about 2 hours cpu time on a desktop PC. Results for the stability of the thermohaline circulation to variable forcing of aspects of the zonal (Atlantic to Pacific) and meridional (tropics to extra-tropics) transport of freshwater will be presented. The multiple ensemble simulations have utilised Condor pools of networked workstations to achieve millions of years of quasi-parallel model integrations. At present, biogeochemistry is being coupled within the ocean and a land surface scheme (based on MOSES) and a dynamic global vegetation model (TRIFFID) are being added, in order to close the carbon cycle. A 3-D atmosphere (IGCM) is in development (currently at T21 resolution with 5 levels), from which a faster 3-D stationary wave model will be derived. A 3-D ice sheet model and marine sediments will also be coupled as components in order to study the behaviour of the Earth system on 30,000+ year timescales. Our initial scientific foci are on simulating the transition from the Last Glacial Maximum to the Holocene and undertaking long-term simulations of human-induced global change.

  8. 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. PMID:24388702

  9. 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 easily adapted to almost any campus setting. A number of factors contribute to self-guided explorations' success. For most students, these are novel, particularly memorable experiences. Interactive in nature, self-guided explorations are also relaxed, self-paced instruction without the pressures that can dominate other educational settings. Well designed explorations build on students' prior knowledge, allowing them to integrate new earth science concepts with familiar ideas and settings. By creating connections between geology and human society, these explorations also make earth science more relevant to students who had not previously considered their world from a geological perspective. By their very nature, explorations are place-centered education which helps ground instruction and makes it more relevant to students without strong science backgrounds. Further these explorations give students control over, and responsibility for, their own learning, which is always a pedagogically sound approach. Finally, self-guided explorations can integrate earth science education into students' social lives as most students choose to complete the explorations in groups, often with friends and family who are not enrolled in the course.

  10. 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.

  11. Absolute light yield measurements on SrF$_{2}$ and BaF$_{2}$ doped with rare earth ions

    E-print Network

    Roman Shendrik; Evgeny Radzhabov

    2013-08-19

    Results of absolute light output measurements on strontium and barium fluoride doped with PrF$_3$ and CeF$_3$ are presented and compared with scintillators having well-known light output (NaI-Tl, CsI-Tl, BGO). For pure SrF$_2$ crystal we obtain a value of about 28600 photons/MeV.

  12. 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

    Universities Space Research Association and Sinte Gleska University (SGU) have teamed with eight Tribal Colleges and Universities (TCUs) to participate in a NASA Earth Science funded project, TRibal Earth Science and Technology Education (TRESTE) project which focuses on TCU faculty teaching undergraduate Earth science courses to non-science and science students, with particular attention to TCU faculty teaching K-12 pre- and in- service teachers. The eight partner TCUs are: Blackfeet Community College (BCC), Browning, MT, Fond du Lac Tribal and Community College, Cloquet, MN, Fort Berthold Community College, New Town, ND, Little Priest Tribal College, Winnebago, NE, Oglala Lakota College, Pine Ridge, SD, Sitting Bull College, Fort Yates, ND, Turtle Mountain Community College, Belcourt, ND, United Tribes Technical College (UTTC), Bismarck, ND. The goal of this 3-year project is to promote the use of NASA Earth science data and products in the classroom thereby enabling faculty to inspire undergraduate students to careers in Earth system science, the physical sciences, and related fields of science and engineering. To accomplish this goal we are targeting three areas: (1) course content - enhance the utilization of Earth system science and physical science concepts, (2) teaching methodology - develop problem-based learning (PBL) methods, and (3) tools and technology - increase the utilization of GIS and remote sensing in the classroom. We also have enlisted ESRI, NativeView and the USGS as collaborators. To date we have held an introductory "needs" workshop at the USGS EROS Data Center and two annual workshops, one at UTTC and the second at BCC. During these annual workshops we have divided our time among the three areas. We have modeled the workshops using the PBL or Case Study approach by starting with a story or current event. Topics for the annual workshops have been Drought and Forest and Grassland Fires. These topics led us into the solar radiation budget, 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.

  13. 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.

  14. 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 investigators)

    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.

  15. New Data Services for Polar Investigators from Integrated Earth Data Applications (IEDA)

    NASA Astrophysics Data System (ADS)

    Nitsche, F. O.; Ferrini, V.; Morton, J. J.; Arko, R. A.; McLain, K.; O'hara, S. H.; Carbotte, S. M.; Lehnert, K. A.; IEDA Team, I.

    2013-12-01

    Accessibility and preservation of data is needed to support multi-disciplinary research in the key environmentally sensitive Polar Regions. IEDA (Integrated Earth Data Applications) is a community-based data facility funded by the US National Science Foundation (NSF) to support, sustain, and advance the geosciences by providing data services for observational solid earth data from the Ocean, Earth, and Polar Sciences. IEDA tools and services relevant to the Polar Research Community include the Antarctic and Southern Ocean Data System (ASODS), the U.S. Antarctic Program Data Coordination Center (USAP-DCC), GeoMapApp, as well as a number of services for sample-based data (SESAR and EarthChem). In addition to existing tools, which assist Polar investigators in archiving their data, and creating DIF records for global searches in AMD, IEDA recently added several new tools and services that will provide further support for investigators with the data life cycle process. These include a data management plan (http://www.iedadata.org/compliance/plan) and data compliance reporting tool (http://www.iedadata.org/compliance/report) that will help investigators comply with the requirements of funding agencies such as the National Science Foundation (NSF). Data, especially from challenging Polar Regions, are likely to be used by other scientists for future studies. Therefore, data acknowledgment is an important concern of many investigators. To encourage data acknowledgments by data users, we link references of publications (when known) to datasets and cruises registered within the ASODS system as part of our data curation services (http://www.marine-geo.org/portals/antarctic/references.php). In addition, IEDA offers a data publication service to register scientific data with DOI's, making data sets citable as publications with attribution to investigators as authors. IEDA is a publication agent of the DataCite consortium. Offering such services provides additional incentives for making data available through data centers. Such tools and services are important building blocks of a coherent and comprehensive (cyber) data support structure for Polar investigators.

  16. Refluxing synthesis, photoluminescence and binding ability to deoxyribonucleic acid of water-soluble rare earth ion-doped LaF3 nanoparticles.

    PubMed

    Wang, Zhenling; Zhang, Yi; Li, Chunyang; Zhang, Xinlei; Chang, Jiazhong; Xie, Jianping; Li, Chengwei

    2014-06-01

    Water-soluble rare earth ion (Ce3+, Tb3+)-doped LaF3 nanoparticles with the ability to bind to deoxyribonucleic acid (DNA) were prepared by the refluxing method in a glycerol/water mixture and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL) spectra, and so on. The obtained LaF3:Ce3+, LaF3:Tb3+ and LaF3:Ce3+, Tb3+ nanoparticles are well crystallized with a hexagonal structure and composed of spherical particles with an average size from 11 to 19 nm. The as-prepared samples can be dispersed into water to form a colloidal solution. Under ultraviolet (UV) light irradiation, the emission lines of Tb3+ in the co-doped LaF3:Ce3+, Tb3+ are evidently strengthened compared to those in the single-doped LaF3:Tb3+ nanoparticles, which is due to the energy transfer from Ce3+ to Tb3+ ions in the LaF3:Ce3+, Tb3+ samples. The biological experiment confirms that the water-soluble LaF3:Ce3+, Tb3+ nanoparticles can be bonded to the DNA molecules and emit visible light under UV irradiation. These luminescent nanoparticles could be used similarly to ethidium bromide (EtBr), which has been used extensively as a DNA staining reagent. The advantage that LaF3:Ce3+, Tb3+ nanoparticles have lower toxicity than EtBr makes them a potential reagent instead of EtBr in the DNA staining in biological experiments. PMID:24738421

  17. 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 [Ruhr-Universitat Bochum; Behrends, F [Westfalische Wilhelsm-Universitat Munster; Cybinska, J [Ruhr Universitat Bochum; Eckert, H [Westfalische Wilhelsm-Universitat Munster; Mudring, Anja -V [Ames Laboratory

    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.

  18. Emission sensitization and mechanisms of electron-excitation migration in structures based on III-nitrides doped with rare-earth elements (Eu, Er, Sm)

    SciTech Connect

    Mezdrogina, M. M., E-mail: margaret.m@mail.ioffe.ru; Danilovsky, E. Yu.; Kuzmin, R. V. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

    2010-03-15

    The effect of doping with Eu, Er, and Sm rare-earth ions on the shape of the luminescence spectrum for heterostructures with GaN/In{sub x}Ga{sub 1-x}N (0.1 < x < 0.4) quantum wells and from p-GaN/n-GaN and p-AlGaN/n-GaN junctions is investigated. The results of measurements of the electroluminescence of these structures correlate with the previous data on photoluminescence and Moessbauer spectroscopy. It is shown that it is the GaN 'yellow' (5000-6000 A) band that plays the important role in the excitation of intracenter states in the structures with several GaN/InGaN quantum wells doped with Eu and Sm. In this case, Eu is most likely the sensitizer for Sm. Additional introduction of 3d metal (Fe{sup 57}) in p-GaN/n-GaN:Eu results in the realization of intracenter transitions in Eu{sup 3+}: {sup 5}D{sub 0} {sup {yields} 7}F{sub 1} (6006 A), {sup 5}D{sub 0} {sup {yields} 7}F{sub 2} (6195 A), {sup 5}D{sub 0} {sup {yields} 7}F{sub 3} (6627 A), and {sup 5}D{sub 1} {sup {yields} 7}F{sub 4} (6327 A) due to the occurrence of new, efficient channels of excitation transfer to intracenter states and in the effect of Fe on the local environment of rare-earth ions including due to the f-d hybridization enhancement.

  19. Synthesis and Characterization of Alkaline-Earth Metal (Ca, Sr, and Ba) Doped Nanodimensional LaMnO3 Rare-Earth Manganites

    NASA Astrophysics Data System (ADS)

    Asma, Khalid; Saadat, Anwar Siddiqi; Affia, Aslam

    2013-07-01

    The substitution of divalent cations of alkaline-earth elements in nanodimensional structures of rare-earth manganites produces advanced materials with potential electrical and magnetic functionalities. A systematic investigation of La0.65A0.35MnO3 (A = Ca, Sr, Ba) materials synthesized with a modified citrate route adopting ethanol dehydration has been undertaken. The structural and morphological analyses are carried out by using x-ray diffraction and scanning electron microscopy, respectively. Resistivity measurements are performed in variation with temperature to study the electrical transport properties which are found to vary with the size of the A-site cationic radius. Room temperature magnetic measurements are carried out to investigate the type of magnetic phase present in materials. The stability of the magnetic phase and coercivity are found to be dependent on the size of nanocrystallites.

  20. Calcium niobium gallium and calcium lithium niobium gallium garnets doped with rare earth ions––effective laser media

    Microsoft Academic Search

    Yu. K Voronko; A. A Sobol; A. Ya Karasik; N. A Eskov; P. A Rabochkina; S. N Ushakov

    2002-01-01

    The results of spectroscopy and laser action of disordered calcium niobium gallium (CNGG) and calcium lithium niobium gallium (CLNGG) garnets doped with Nd3+, Eu3+, Er3+, Ho3+ and Tm3+ were displayed. The structure and some optical and physical properties of CNGG and CLNGG-crystals were studied. Activator centers construction and the mechanism of inhomogeneous broadening and splitting of spectral lines of rare

  1. Integrating Diverse Geophysical and Geological Data to Construct MultiDimensional Earth Models: The Open Earth Framework

    Microsoft Academic Search

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

    2008-01-01

    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

  2. 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, challenges and successes, best practices, and opportunities for future work and collaboration.

  3. 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.

  4. 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.

    Development of reliable and robust strategies for long-term life support for planetary exploration must be built from real-time experimentation to verify and improve system components. Also critical is incorporating 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 which has been developed by the authors along with others previously advanced ("Mars on Earth ®") in the light of three years of experimentation 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 an average of 46% (53% for best crop) ultradwarf (Apogee) wheat by 9% (23% for best crop), pinto bean by 13% (31% for best crop). 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. But soil also offers distinct advantages: the capability to be created on the Moon or Mars using in situ space resources, reduces long-term reliance on consumables and imported resources, and more readily recycling and incorporating crew and crop waste products. In addition, a living soil contains a complex microbial ecosystem which helps prevent the buildup of trace gases or compounds, and thus assist with air and water purification. The atmospheric dynamics of these crops were studied in the Laboratory Biosphere adding to the database necessary for managing the mixed stands of crops essential for supplying a nutritionally 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.

  5. 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…

  6. 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.e. propellant consumption) and transit times.

  7. CEOS WGISS Integrated Catalog, A Catalog for Earth Observation Satellite Data

    NASA Astrophysics Data System (ADS)

    Enloe, Y.; Yapur, M.

    2011-12-01

    The Committee on Earth Observation Satellites (CEOS) was formed in 1984 to coordinate the world's civil space-borne observations of the Earth. More recently, CEOS and its member agencies have committed to provide the implementation of the space-based component of the Group on Earth Observation (GEO) Global Earth Observation System of Systems (GEOSS) Common Infrastructure (GCI). In the case of CEOS, there are a number of challenges in directly connecting the components and services of its member agencies to the GCI. In many cases, the existing catalog systems of the member agencies do not support the OGC Catalog Service for the Web (CSW) that has been selected as the standard for the GCI. Another challenge is related to the fact that collections of satellite data products are extremely large and constantly growing with millions of individual products. Harvesting the associated metadata into the clearinghouse of the GCI is not a practical alternative. In addition, the collection/granule hierarchy and unique spatial/temporal characteristics of satellite data and the user registration and asynchronous access requirements of the agency systems pose additional challenges. The CEOS approach has been to design and implement a CEOS WGISS Integrated Catalog (CWIC) that will serve as a community catalog of the products and services that are offered through its member's systems. CWIC will be based on a distributed search architecture and serve as a gateway between the GEO portal or community portals and clients and the CEOS agency systems. CWIC will receive standard search queries from these portals or clients all using the GEO supported catalog standard, the OGC CSW 2.0.2 and the WGISS Search Criteria for granule search and translate them into the native protocols of the underlying catalogs. Likewise, the result sets from the CEOS agency catalogs will be converted to the form that will be compatible with the portals and clients. The CWIC data provider partners include NOAA, NASA, USGS, INPE (Brazil), and two Chinese data centers coordinated by the Chinese Academy of Science have joined the engineering team and their systems are accessible via CWIC. In addition, multiple other CEOS agencies are or plan to be members of the teams developing community portals and clients that will access CWIC. Recently, NASA initiated development of a prototype client to access CWIC. The ultimate goal of the CEOS WGISS effort is to make the satellite data and services of its member agencies more accessible and useful to the broad set of GEO research programs and applications and this is most effectively approached by harmonization within the satellite community. This kind of community-based development with the harmonization occurring first within the community and then being offered to the broader GEO systems fits the original GEO vision of becoming "a system of systems", clearly representing a contribution towards achieving full interoperability in a standards-based manner.

  8. 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.

  9. Few-mode erbium-doped fiber amplifier design method based on the signal-pump overlap integral

    NASA Astrophysics Data System (ADS)

    Herbster, Adolfo F.; Romero, Murilo A.

    2014-09-01

    Space-division multiplexing allows an increase of link capacity by using either multicore or single-core few-mode (FM) optical fibers. In the case of FM systems, each mode carries its own data stream and long-haul transmission can be hampered by the use of conventional erbium-doped fiber amplifiers (EDFAs), since because of distinct field profile configurations, each mode experiences a different value of optical gain. The role of the FM-EDFA designer, usually done by solving rate and propagation equations, is to define both the fiber cross-section and the pumping configuration to provide the best possible mode equalization of optical gain and noise figure. An optimization method is proposed here based on the definition of a figure of merit related to the equalization of the pump-mode signal overlap integral, significantly reducing computation time and allowing a multiobjective optimization approach. The results obtained were validated against the solution provided by the full set of rate and propagation equations and we conducted an FM-EDFA optimization case study. Our double-ring Er doping profile design requires a single 180-mW LP11 pump to provide a mean gain of 21.3 dB, within 0.6 dB of equalization for each of the four modes considered.

  10. An integrative 'omics' solution to the detection of recombinant human erythropoietin and blood doping.

    PubMed

    Pitsiladis, Yannis P; Durussel, Jérôme; Rabin, Olivier

    2014-05-01

    Administration of recombinant human erythropoietin (rHumanEPO) improves sporting performance and hence is frequently subject to abuse by athletes, although rHumanEPO is prohibited by the WADA. Approaches to detect rHumanEPO doping have improved significantly in recent years but remain imperfect. A new transcriptomic-based longitudinal screening approach is being developed that has the potential to improve the analytical performance of current detection methods. In particular, studies are being funded by WADA to identify a 'molecular signature' of rHumanEPO doping and preliminary results are promising. In the first systematic study to be conducted, the expression of hundreds of genes were found to be altered by rHumanEPO with numerous gene transcripts being differentially expressed after the first injection and further transcripts profoundly upregulated during and subsequently downregulated up to 4 weeks postadministration of the drug; with the same transcriptomic pattern observed in all participants. The identification of a blood 'molecular signature' of rHumanEPO administration is the strongest evidence to date that gene biomarkers have the potential to substantially improve the analytical performance of current antidoping methods such as the Athlete Biological Passport for rHumanEPO detection. Given the early promise of transcriptomics, research using an 'omics'-based approach involving genomics, transcriptomics, proteomics and metabolomics should be intensified in order to achieve improved detection of rHumanEPO and other doping substances and methods difficult to detect such a recombinant human growth hormone and blood transfusions. PMID:24627340

  11. Progress in crystal growth and characterisation of rare-earth doped non-linear KTP crystals for laser applications

    Microsoft Academic Search

    C. Zaldo; M Rico; F D??az; J. J Carvajal

    1999-01-01

    The incorporation of rare earth ions into KTiOPO4 crystals and into other isomorphous phases is more efficient for impurities of small ionic radius. Some of the Nd3+ and Er3+ spectroscopic properties in KTiOPO4 (KTP) and RbTiOPO4 (RTP) are discussed to illustrate the contribution of several centres to the optical absorption and photoluminescence properties. The Nd3+ centres observed in KTiOPO4 crystals

  12. Effect of sodium doping of rare-earth iron garnet films on magnetic and magneto-optic properties

    SciTech Connect

    Ramesh, M.; Silliman, S.D.; Peruyero, J.; Stancil, D.D. (Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania (USA)); Gualtieri, D.M. (Applied Physics Laboratory, Allied-Signal, Inc., P.O. Box 1021-R, Morristown, New Jersey (USA))

    1991-11-15

    Bismuth-doped lutetium iron garnet (BLIG) is an important material for implementation of the interaction between magnetostatic waves and optical guided modes. Sodium oxide is suggested to reduce the viscosity of the lead-free melt used for liquid-phase epitaxy (LPE) growth of the films, improving flux removal. The effect of the incorporation of sodium into the garnet lattice on the important magnetic and magneto-optic properties is studied, using yttrium iron garnet as a model system. Negligible effect on the Faraday rotation and magnetostatic wave passband is noted. The uniaxial anisotropy field is affected in the negative direction by a growth induced anisotropy due to sodium inclusion, but this effect may be removed by annealing.

  13. Structural characterization of rare-earth doped soda magnesia alumina silica glasses for holographic storage: Brillouin, Raman and NMR spectroscopy studies

    NASA Astrophysics Data System (ADS)

    Utegulov, Zhandos Nurpeisovich

    Scope and method of study. This work was directed to perform (Brillouin and Raman) light scattering and (29Si, 27Al, 23Na) MAS NMR spectroscopies to study structural, vibrational, elastic, photoelastic and magnetic properties of Eu3+ -doped soda magnesia alumina silica (EDSMAS) glasses as a function of content of individual components: Eu2O3, Al 2O3 and Na2O to provide new knowledge related to the mechanism underlying the formation of holographic gratings in these materials. Findings and conclusions. Europium doping and alumina substitution for silica causes glass to become harder but at the same time more polarizable. In both glass series the enhanced hardness is due to reduction of the free space. In addition, in the former case the europiums have high coordination and enhanced field strength with oxygen atoms. In the latter one, the aluminums entering the glass recover Si-O-Si bridges by attracting charge balancing modifiers from depolymerized SiO4 network. Growing polarizability in Eu- and Al-series is mostly due to depolymerization by Eu 3+ doping and the appearance of AlO4 tetrahedral groups weakly bound to sodium ions, respectively. The Eu3+ ions form the broad distribution of Qn species with possible clustering of rare-earths at large Eu3+ ion concentration, while sodium ions entering the glass cause the formation of rather distinct Qn species. In Na-series the glass becomes more depolymerized although less compressible in the volumetric sense . In this series Na environment is sensitive to the first neighbor Na+ network-modifiers. The overall bonding in all three EDSMAS glass series becomes more polarizable compared to fused silica. The depolymerization (polymerization) of the EDSMAS glass is mainly characterized by the presence of NBOs (BOs) and three (four) member silicate and aluminosilicate rings. Si and Al atoms were found to be in tetrahedrally coordinated sites. No Al was observed in 6- or 5-fold coordinated sites. Lorentz-Lorentz effect was the dominant contribution to the photoelastic constant P 12. The strength of the holographic storage signal is defined by many factors among which the number of the excited Eu3+ ions, the high-energy phonons associated with Si-NBO vibrations, weakly bound Na+ ions charge balancing [AlO4]- complexes and the stability of the traps for the mobile light ions play very important roles.

  14. 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.

  15. 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.

  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. Potential Uses of EarthSLOT (an Earth Science, Logistics, and Outreach Terrainbase) for Education and Integration in the International Polar Year

    NASA Astrophysics Data System (ADS)

    Nolan, M.

    2004-12-01

    EarthSLOT is an internet-based, 3D, interactive terrain and data visualization system that may have many potential uses as an education and integration tool for International Polar Year projects. Recently funded by NSF's Office of Polar Programs for use in the Arctic, the global nature of the application lends itself well for use at both poles and everywhere in between. The application allows one to start with a spinning earth and zoom down to surface level. The highest resolution digital elevation models available provide the necessary 3D topographic perspective and a variety of possible high-resolution satellite and aerial imagery layers add surface realism; resolution can be down to the centimeter level for either type of data, and frequently acquired satellite imagery may be updated automatically as it arrives. Superimposed on this can be nearly any form of vector or annotation layers, such as shapefiles, polygons, point data, and 3D models (still and moving), which can be easily imported from existing GIS applications or spreadsheets. External databases can also be queried and the results served seamlessly. The entire application is served over the internet, and any connection with speeds over 300kps allows one to interactively fly with a minimum of performance lag. EarthSLOT stands for Earth Science, Logistics, and Outreach Terrainbase, targeting the user-groups of scientists, logisticians, and the public. Approved scientific users can add their own vector content to the application on their own, such that they can create their own custom applications featuring their data but using our underlying earth model with a minimum of interaction with us. For example, an oceanographer can add ship tracks or buoy locations to the model with links to data, host the link on his or her own web page, and invite collaborators to view the spatial relationship of their data to underlying bathymetry. Logisticians or program managers interested in understanding the spatial relationships between different projects for the purposes of coordinating or facilitating cost sharing of logistics can add layers that show the locations and timing of their projects. Educators or principle investigators interested in outreach can design and implement custom applications to share the motivation, rationale, and results of their work in a large variety of ways. Each of these applications can be freely-shared or password-protected, depending on their nature, on either project home pages or on a central IPY-EarthSLOT site. Our prototype application can be found on-line at www.earthslot.org. We already have substantial Landsat coverage of the Arctic, and in the near future plan to incorporate high resolution mosaics of Greenland and Antarctica. With modest additional funding, we propose that EarthSLOT could be used a central integration tool for projects related to the International Polar Year.

  18. Integrating NASA Earth Science Enterprise (ESE) Data Into Global Agricultural Decision Support Systems

    NASA Astrophysics Data System (ADS)

    Teng, W.; Kempler, S.; Chiu, L.; Doraiswamy, P.; Liu, Z.; Milich, L.; Tetrault, R.

    2003-12-01

    Monitoring global agricultural crop conditions during the growing season and estimating potential seasonal production are critically important for market development of U.S. agricultural products and for global food security. Two major operational users of satellite remote sensing for global crop monitoring are the USDA Foreign Agricultural Service (FAS) and the U.N. World Food Programme (WFP). The primary goal of FAS is to improve foreign market access for U.S. agricultural products. The WFP uses food to meet emergency needs and to support economic and social development. Both use global agricultural decision support systems that can integrate and synthesize a variety of data sources to provide accurate and timely information on global crop conditions. The Goddard Space Flight Center Earth Sciences Distributed Active Archive Center (GES DAAC) has begun a project to provide operational solutions to FAS and WFP, by fully leveraging results from previous work, as well as from existing capabilities of the users. The GES DAAC has effectively used its recently developed prototype TRMM Online Visualization and Analysis System (TOVAS) to provide ESE data and information to the WFP for its agricultural drought monitoring efforts. This prototype system will be evolved into an Agricultural Information System (AIS), which will operationally provide ESE and other data products (e.g., rainfall, land productivity) and services, to be integrated into and thus enhance the existing GIS-based, decision support systems of FAS and WFP. Agriculture-oriented, ESE data products (e.g., MODIS-based, crop condition assessment product; TRMM derived, drought index product) will be input to a crop growth model in collaboration with the USDA Agricultural Research Service, to generate crop condition and yield prediction maps. The AIS will have the capability for remotely accessing distributed data, by being compliant with community-based interoperability standards, enabling easy access to agriculture-related products from other data producers. The AIS? system approach will provide a generic mechanism for easily incorporating new products and making them accessible to users.

  19. 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.

  20. Earth System Modeling—An Integrated Assessment Tool for Environmental Studies

    Microsoft Academic Search

    R. A. PIELKE

    This paper overviews a wide spectrum of influences on the Earth's climate system. These include external effects, such as variations in the solar energy output, and internal influences. Internal influences include both natural and human-caused effects. The feedbacks associated with the Earth's climate system are nonlinear and occur over a range of time and space scales. As a result, our

  1. A coupled and workflow integrated modeling system applications for earth system science

    Microsoft Academic Search

    Ufuk Utku Turuncoglu; Nuzhet Dalfes; Sylvia Murphy; Cecelia Deluca

    2010-01-01

    The complexity of earth system models and their applications are getting increase because of the continued development of computational resources, storage systems and distributed high-resolution observation networks. Therefore, the multi component earth system models that are used to develop these applications need to be designed in a new programming approach to make easy interaction among those model components and in

  2. Optimum DMOS cell doping profiles for high-voltage discrete and integrated device technologies

    NASA Astrophysics Data System (ADS)

    Shenai, Krishna

    1992-05-01

    It is shown that the implantation and activation sequences of B and As result in significant variations in the contact resistance and p-base sheet resistance beneath the n+-source diffusion of a DMOSFET cell. For identical process parameters, the contact resistance of As-doped n+ silicon was significantly improved when high-dose B was implanted due to higher As surface concentration. The SUPREM III process modeling results were found to be in qualitative agreement with the measured spreading resistance profiles and the discrepancies could be attributed to larger high-temperature diffusion constants used in SUPREM III and the coupled As-B diffusion/activation effects that are not accounted for in process modeling. The experimental results are discussed within the framework of fabricating high-performance DMOSFET cells and CMOS high-voltage devices on the same chip for discrete and smart-power applications.

  3. Low noise fiber laser based on gain feedback in a rare-earth doped fiber amplifier chain

    NASA Astrophysics Data System (ADS)

    Wan, Hongdan; Gong, Yue; Li, Xianqin; Chen, Jinlong; Wu, Peichun; Sun, Xiaohan

    2012-02-01

    We demonstrate a low noise fiber laser (LN-FL) based on gain feedback controlled high efficiency fiber amplifier chain (FAC) which connect with other optical devices in a circle manner. The FAC contains two cascaded fiber amplifiers with core pumped and double-clad pumped Erbium and Erbium-Ytterbium co-doped fibers. Gain saturation effect and amplified spontaneous emission noise in the FAC is analyzed and suppressed through gain control method. Lasing mode in the LN-FL is stabilized with fiber pigtails setting in special orbits and ensuring fiber device splicing loss low without any filters. For continuous wave operation, mode-hopping free laser spectrum with output power of 2W and SNR of 50dB is achieved. The narrowest bandwidths are about 0.2nm and 0.01nm for lasing cavity without and with filters, respectively. Lasing wavelength can be tuned in a wavelength span of 7nm by adjusting of a fiber pigtailed polarization controller. Pulsed operation of the laser under different pump seeds injection is experimental investigated and analyzed.

  4. 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.

  5. Dielectric and nonlinear current-voltage characteristics of rare-earth doped CaCu3Ti4O12 ceramics

    NASA Astrophysics Data System (ADS)

    Liu, Laijun; Fang, Liang; Huang, Yanmin; Li, Yunhua; Shi, Danping; Zheng, Shaoying; Wu, Shuangshuang; Hu, Changzheng

    2011-11-01

    CaCu3Ti4O12 (CCTO) ceramics doped with rare earth (RE) oxides, including Y2O3, La2O3, Eu2O3, and Gd2O3, were prepared by the traditional solid-state reaction method in order to investigate the effect of RE oxide dopants on the electrical properties as a varistor. The phase identification and morphology of the ceramics were investigated by x-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. A high voltage measuring unit and precision impedance analyzer were used to determine the nonohmic (J-E) behaviors and measure the dielectric properties and impedance spectroscopy of the ceramics, respectively. The results showed that RE oxides enhanced greatly the breakdown electric flied but reduced the nonlinear coefficient and the mean grain size of CCTO ceramics. There was a good linear relationship between ln J and E1/2, which demonstrated that the Schottky barrier should exist at the grain boundary. A double Schottky barrier model composed of a depletion layer and a negative charge sheet was proposed, analogous to the barrier model for ZnO varistors. The depletion layer width determined by diffusion distance of RE ions and the effective surface states played important roles on the electrical properties of the ceramics.

  6. 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.

  7. Developing a geographic information system (GIS) to integrate earth science data: Hygiene Quadrangle, Boulder county, Colorado

    E-print Network

    Nonsung, Sawat

    1993-01-01

    The purpose of this research was to develop a methodology using a geographic information system (GIS) to map and model the best use of earth resources in Hygiene Quadrangle, Boulder County of Colorado. The Spatial Analysis System (SPANS GIS...

  8. 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.

  9. 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 small spacecraft and emerging information technologies, and how sensor web options may be realized and made affordable. Specialized detector subsystems and precision flying techniques may still require substantial innovation, development time and cost: we have presented the considerations for these issues. Finally, data and information gathering and compression techniques are also briefly described.

  10. 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 of scientific instruments such as GPS and probeware, fostered additional student interest in earth science. IDGE has shown to have a lasting effect on the participating students who learn from the experience that science is a dynamic field in need of creative minds who want to make discoveries. Through relevant inquiry, the quality of geoscience instruction is inspiring a new generation of geoscientists. This work was supported in part by the National Science Foundation under award 0735596. Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect those of the National Science Foundation.

  11. Thermophysical Properties of Rare-Earth-Stabilized Zirconia and Zirconate Pyrochlores as Surrogates for Actinide-Doped Zirconia

    NASA Astrophysics Data System (ADS)

    Shimamura, Keiichi; Arima, Tatsumi; Idemitsu, Kazuya; Inagaki, Yaohiro

    2007-06-01

    Thermophysical properties of rare-earth-stabilized zirconia and zirconate pyrochlores, A2Zr2O7 (A = La, Nd, Sm, Gd, Dy, Y), were evaluated by X-ray diffractometry, Raman spectroscopy, and the ultrasound pulse-echo method. Crystallographic analyses elucidated that La2Zr2O7, Nd2Zr2O7, Sm2Zr2O7, and Gd2Zr2O7 had the pyrochlore structure, whereas Dy2Zr2O7 and Y2Zr2O7 had the defect fluorite structure. For lanthanide pyrochlores, the thermal expansion became smaller with increasing ionic radius of A and increasing crystal binding energy. The elastic moduli and Debye temperature evaluated using longitudinal and transverse sound velocities also depend on the ionic radius and binding energy, and hence these values related to mechanical properties increase with the ionic radius of A. On the other hand, Poisson’s ratio was almost comparable among these pyrochlores. In addition, thermophysical properties of actinide pyrochlore are discussed in this study.

  12. Characteristics of rare earth (RE = Eu, Tb, Tm)-doped Y2O3 phosphors for thermometry.

    PubMed

    Ishiwada, Naohiro; Ueda, Toshihisa; Yokomori, Takeshi

    2011-01-01

    The temperature-dependent photoluminescences of Y(2)O(3) : Eu (6% Eu), Y(2)O(3) : Tb (4% Tb) and Y(2)O(3) : Tm (1% Tm) were investigated for high-temperature phosphor thermometry. Two different phases, the monoclinic phase and cubic phase, were considered because the fluorescence spectra vary with the phase. To employ the intensity ratio method, we investigated their photoluminescence spectra under the excitation light of an Hg-Xe lamp as the temperature was elevated from room temperature to more than 1200 K. As a result, it was confirmed that the luminescence intensity of all of the phosphors varied with elevating temperature, i.e. thermal quenching, with the variations depending on the type of rare earth impurity and their phases. The results indicate that Y(2)O(3) : Eu phosphors are applicable to the intensity ratio method because they show appropriate variations in the intensity ratio of two emission lines, and they also have strong and sharp peak intensities without excessive optical noise or black body radiation over a wide range of temperatures. The intensity ratios for Y(2)O(3) : Tb provide such small variations with temperature that the temperature resolution is low, despite the strong emission intensities. As for Y(2) O(3) :Tm, the intensity ratios also have a low temperature resolution and their emission intensities are weak. Therefore, Y(2)O(3) : Tb and Y(2)O(3) : Tm are not appropriate for the intensity ratio method for phosphor thermometry. PMID:20737651

  13. Local-damascene-finFET DRAM integration with p\\/sup +\\/ doped poly-silicon gate technology for sub-60nm device generations

    Microsoft Academic Search

    Yong-Sung Kim; Sang-Hyeon Lee; Soo-Ho Shin; Sung-Hee Han; Ju-Yong Lee; Jin-Woo Lee; Jun Han; Seung-Chul Yang; Joon-Ho Sung; Eun-Cheol Lee; Bo-Young Song; Dong-Jun Lee; Dong-Il Bae; Won-Suk Yang; Yang-Keun Park; Kyu-Hyun Lee; Byung-Hyuk Roh; Tae-Young Chung; Kinam Kim; Wonshik Lee

    2005-01-01

    We integrate FinFET DRAM in sub-60nm feature size. To avoid severe passing gate effects in FinFET cell array, we introduce a local damascene gate structure. Threshold voltage control of the ultra thin body transistors is successfully achieved by adopting p+ boron in-situ doped poly-silicon gate on the FinFET cells. As a result, very stable and uniform operation of FinFET cells

  14. Crystal, electronic structures and photoluminescence properties of rare-earth doped LiSi 2N 3

    NASA Astrophysics Data System (ADS)

    Li, Y. Q.; Hirosaki, N.; Xie, R. J.; Takeka, T.; Mitomo, M.

    2009-02-01

    The crystal and electronic structures, and luminescence properties of Eu 2+, Ce 3+ and Tb 3+ activated LiSi 2N 3 are reported. LiSi 2N 3 is an insulator with an indirect band gap of about 5.0 eV (experimental value ˜6.4 eV) and the Li 2 s, 2 p states are positioned on the top of the valence band close to the Fermi level and the bottom of the conduction band. The solubility of Eu 2+ is significantly higher than Ce 3+ and Tb 3+ in LiSi 2N 3 which may be strongly related to the valence difference between Li + and rare-earth ions. LiSi 2N 3:Eu 2+ shows yellow emission at about 580 nm due to the 4 f65 d1?4 f7 transition of Eu 2+. Double substitution is found to be the effective ways to improve the luminescence efficiency of LiSi 2N 3:Eu 2+, especially for the partial replacement of (LiSi) 5+ with (CaAl) 5+, which gives red emission at 620 nm, showing highly promising applications in white LEDs. LiSi 2N 3:Ce 3+ emits blue light at about 450 nm arising from the 5 d1?4 f15 d0 transition of Ce 3+ upon excitation at 320 nm. LiSi 2N 3:Tb 3+ gives strong green line emission with a maximum peak at about 542 nm attributed to the 5D 4? 7F J ( J=3-6) transition of Tb 3+, which is caused by highly efficient energy transfer from the LiSi 2N 3 host to the Tb 3+ ions.

  15. 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 for a GeoPass account ID, write a proposal to NSF and create a data plan using the IEDA Data Management Plan Tool. Having received the grant, the investigator then collects rock samples on a scientific cruise from dredges and registers the samples with IGSNs. The investigator then performs analytical geochemistry on the samples, and submits the full dataset to the Geochemical Resource Library for a dataset DOI. Finally, the investigator writes an article that is published in Science Direct. Knowing any of the following IDs: Investigator GeoPass ID, NSF Award Number, Cruise ID, Sample IGSNs, dataset DOI, or publication DOI, a user would be able to navigate to all samples, datasets, and publications in IEDA and external systems. Use of persistent identifiers to link heterogeneous data systems in IEDA thus increases access, discovery, and proper citation of hard-earned investigator datasets.

  16. Superconducting Transition Temperatures of up to 47 K from Simultaneous Rare-Earth Element and Antimony Doping of 112-Type CaFeAs2

    NASA Astrophysics Data System (ADS)

    Kudo, Kazutaka; Kitahama, Yutaka; Fujimura, Kazunori; Mizukami, Tasuku; Ota, Hiromi; Nohara, Minoru

    2014-09-01

    The effects of simultaneous Sb doping on the superconductivity of 112-type Ca1?xRExFeAs2 (RE = La, Ce, Pr, and Nd) were studied through measurements of the magnetization and electrical resistivity. In Sb-free materials, the superconducting transition temperature Tc of the La-doped sample was 35 K, while those of the Pr- and Nd-doped samples were ˜10 K; no superconductivity was observed in the Ce-doped sample. Sb doping increased the Tc of all RE-doped samples: Tc increased to 47, 43, 43, and 43 K for RE = La, Ce, Pr, and Nd, respectively. We also found that the enhanced superconductivity results from the increase in the lattice parameter b, which increases the As–Fe–As bond angle to be closer to the ideal tetrahedron value. These observations provide insight for further increasing the Tc of the 112 phase.

  17. 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…

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

    Microsoft Academic Search

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

    2005-01-01

    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

  19. 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.

  20. "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…

  1. Thermally deposited Ag-doped CdS thin film transistors with high-k rare-earth oxide Nd{sub 2}O{sub 3} as gate dielectric

    SciTech Connect

    Gogoi, P., E-mail: paragjyoti_g@rediffmail.com [Sibsagar College, Material Science Laboratory, Department of Physics (India)

    2013-03-15

    The performance of thermally deposited CdS thin film transistors doped with Ag has been reported. Ag-doped CdS thin films have been prepared using chemical method. High dielectric constant rare earth oxide Nd{sub 2}O{sub 3} has been used as gate insulator. The thin film trasistors are fabricated in coplanar electrode structure on ultrasonically cleaned glass substrates with a channel length of 50 {mu}m. The thin film transistors exhibit a high mobility of 4.3 cm{sup 2} V{sup -1} s{sup -1} and low threshold voltage of 1 V. The ON-OFF ratio of the thin film transistors is found as 10{sup 5}. The TFTs also exhibit good transconductance and gain band-width product of 1.15 Multiplication-Sign 10{sup -3} mho and 71 kHz respectively.

  2. Native American Science Education: A Compelling Opportunity for the Integration of Earth and Space Science

    Microsoft Academic Search

    C. A. Morrow; N. Maryboy; D. Begay

    2005-01-01

    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

  3. Integrated Earth Science Research in Deep Underground Science and Engineering Laboratories

    Microsoft Academic Search

    J. S. Wang; T. C. Hazen; M. E. Conrad; L. R. Johnson; R. Salve

    2004-01-01

    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

  4. 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.

  5. 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.

  6. Durability of glasses from the Hg-doped Integrated DWPF Melter System (IDMS) campaign

    SciTech Connect

    Jantzen, C.M.

    1992-08-30

    The Integrated DWPF Melter System (IDMS) for the vitrification of high-level radioactive wastes is designed and constructed to be a 1/9th scale prototype of the full scale Defense Waste Processing Facility (DWPF) melter. The IDMS facility is the first engineering scale melter system capable of processing mercury, and flowsheet levels of halides and noble metals. In order to determine the effects of mercury on the feed preparation process, the off-gas chemistry, glass melting behavior, and glass durability, a three-run mercury (Hg) campaign was conducted. The glasses produced during the Hg campaign were composed of Batch 1 sludge, simulated precipitate hydrolysis aqueous product (PHA) from the Precipitate Hydrolysis Experimental Facility (PHEF), and Frit 202. The glasses were produced using the DWPF process/product models for glass durability, viscosity, and liquidus. The durability model indicated that the glasses would all be more durable than the glass qualified in the DWPF Environmental Assessment (EA). The glass quality was verified by performing the Product Consistency Test (PCT) which was designed for glass durability testing in the DWPF.

  7. A technique for modelling p- n junction depletion capacitance of multiple doping regions in integrated circuits

    NASA Astrophysics Data System (ADS)

    Pinkham, Raymond; Anderson, Daniel F.

    1986-08-01

    The continuing advancements in integrated circuit technology have placed new burdons on the circuit design engineer, who must rely extensively upon computer simulation to correctly predict circuit behavior. One challenge is to develop better modelling techniques to more accurately deal with complex p- n junction structures often used in modern VLSI designs. This paper presents an easily implemented method for deriving parameters which accurately model the behavior of MOS VLSI structures containing complex p- n junction capacitance components. The methodology is applicable to both planar and laterally diffused junctions, whether formed by direct ion implantation or by diffusion from a finite or infinite source. The theories behind the equations used and results of the application of this new technique are discussed. A flow chart for a fitter program based on the new method is presented and described. The corresponding program written for the TI-59 scientific programmable calculator is available. Final model parameters are given and are shown to produce a numerical capacitance model which is accurate to within 2%.

  8. 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 spatially extensive, from sub-room-size scale to ten-kilometer scale. The DUSEL sites with vertical depth and lateral extent can accommodate many different experiments. Hydrologic studies can characterize the in-flow along drifts, ramps, and shafts. Geophysical and rock mechanics studies can have seismic and electromagnetic sensors stationed on site, for both local monitoring of excavations and long-term stability, and mine-scale network of sensors to form a large aperture for tomography imaging. The geo-biochemical studies can include the ecological evaluation of the effects of introduced materials and the search for the origin of life in isolated fluid pockets at depth. The muon flux can be measured underground to detect empty space (or lack of it) above detectors, as demonstrated at the Chephren pyramid, Egypt, in the 1970s and currently at the Pyramid of the Sun, Mexico. Conventional geophysical tomography, with wave propagation through rock mass, can be extended to include particle rays, with high-energy muon flux as an example. Muons interacting with atoms have implications for both geochemical and biological processes. This type of research can further promote collaboration between earth scientists with physicists. A deep laboratory can accommodate a deep campus for suites of physics detectors, and several campuses at different depths within the same site for earth science experiments in rock mechanics, hydrology, geochemistry, ecology, geo-microbiology, coupled processes, and many other branches of earth and planetary sciences.

  9. Calculation of Spin-Hamiltonian Parameters for Gadolinium Ion Doping Isostructural Series of Rare-Earth Metal Trichloride Hexahydrates and Trifluorides.

    NASA Astrophysics Data System (ADS)

    Lewis, Norman Robert

    1982-03-01

    Spin-Hamiltonian parameters are calculated for Gd('3+) doping the isostructural rare-earth metal series RCl(,3)(.)6H(,2)O (R = Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm) and RF(,3) (R = La, Ce, Pr, Nd). The theory of spin-Hamiltonian parameters (SHPs) and of crystal-field parameters (CFPs) is presented, and the relationship between them is discussed. Consideration is given to the question of the validity of the crystal -field parameterization scheme and to the question of whether or not the SHPs arise soley from terms which are linear in the crystal field. The SHPs for the two series are calculated on the basis of the super-position model (SM) of Newman using a newly developed method which exploits the consistency of the model to determine distortions in the ionic positions. It is also shown how the SM may be reformulated so as to decouple the model parameter values from metal-ligand distance effects. In addition, the SHPs are calculated for the same two series using a model original to this work, called the point-charge plus induced-dipole model (PCID). This is based on the use of polarizability tensors whose symmetry conforms to that of the host crystal. These tensors are required in order to calculate the induced dipole moments at the various ion sites. Thus, the SHPs are expressed in terms of point-charge sums and induced -dipole sums over the crystal, all sums being evaluated by Ewald's method. Although different polarizability values are found for each ion type for each host, these values are not arbitrary parameters as would arise in a purely empirical model. This is because they are subject to various physical constraints, as is discussed. Also, the polarizability values predicted by the model are found to vary with the host-ion radius in a way consistent with that predicted by the exchange charge model of Dick and Overhauser. Both the SM and the PCID model give results for the SHPs within experimental error. A review is given of existing polarizable dipole models. It is shown that all of these neither provide a rigorous treatment of the polarizability problem, nor do they agree well with experiment. Also there is presented a detailed treatment of Ewald's method including a newly developed technique for the evaluation of correction terms which occur in the theory. Conclusions are made regarding the validity and utility of the PCID model.

  10. 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.

  11. On an improved sub-regional water resources management representation for integration into earth system models

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    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 options of not accounting for groundwater withdrawals, or on the contrary, of assuming that all remaining demand is met through groundwater extractions, are discussed.

  12. On an improved sub-regional water resources management representation for integration into earth system models

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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 and predictors (withdrawals vs. consumptive demands, as well as natural vs. regulated mean flow) for configuring operating rules. Overall the best performing implementation is with combined priorities rules (flood control storage targets and irrigation release targets) set up with mean annual natural flow and mean monthly withdrawals. The options of not accounting for groundwater withdrawals, or on the contrary, of assuming that all remaining demand is met through groundwater extractions, are discussed.

  13. 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.

  14. Microwave-assisted one-pot synthesis of water-soluble rare-earth doped fluoride luminescent nanoparticles with tunable colors

    PubMed Central

    Mi, Cong-Cong; Tian, Zhen-huang; Han, Bao-fu; Mao, Chuan-bin; Xu, Shu-kun

    2012-01-01

    Polyethyleneimine (PEI) functionalized multicolor luminescent LaF3 nanoparticles were synthesized via a novel microwave-assisted method, which can achieve fast and uniform heating under eco-friendly and energy efficient conditions. The as-prepared nanoparticles possess a pure hexagonal structure with an average size of about 12 nm. When doped with different ions (Tb3+ and Eu3+), the morphology and structure of the nanoparticles were not changed, whereas the optical properties varied with doped ions and their molar ratio, and as a result emission of four different colors (green, yellow, orange and red) were achieved by simply switching the types of doping ions (Eu3+ versus Tb3 +) and the molar ratio of the two doping ions. PMID:22879690

  15. Earth Systems Science Earth Systems Science at UNH

    E-print Network

    Pringle, James "Jamie"

    Earth Systems Science Earth Systems Science at UNH THE UNH Institute for the Study of Earth, Oceans, and Space (EOS) Earth Systems Research Center is dedicated to understanding the Earth as an integrative scientists and students study the Earth's ecosystems, atmosphere, water, and ice using field measurements

  16. Fabrication and optical properties of selected coreshell structures with nanocrystalline rare-earth doped phosphors coated with SiO2 submicron particles

    Microsoft Academic Search

    P. Psuja; L. Marciniak; D. Hreniak; W. Strek

    2007-01-01

    In the first step silica submicron particles were prepared by the sol-gel method. Then obtained cores were occluded with a precursor of terbium doped yttrium aluminum garnet (YAG). The same procedure was repeated for europium doped tin dioxide. The morphology and structure of obtained shell materials were determined by powder X-ray diffraction (XRD) and transmission electro-microscopy (TEM) analyses. Luminescent properties

  17. 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…

  18. Physicochemical properties of rare earth doped ceria Ce0.9Ln0.1O1.95 (Ln = Nd, Sm, Gd) as an electrolyte material for IT-SOFC/SOEC

    NASA Astrophysics Data System (ADS)

    Chaubey, Nityanand; Wani, B. N.; Bharadwaj, S. R.; Chattopadhyaya, M. C.

    2013-06-01

    Nanosized crystallites of rare earth doped ceria Ce0.9Ln0.1O1.95 (Ln = Nd, Sm, Gd) a promising electrolyte material for Intermediate Temperature - Solid Oxide Fuel Cells/electrolysis cells have been synthesized by standard ceramic route. Detection of impurities in the samples was done by FTIR spectroscopy. X-ray diffraction studies were used for the determination of phase purity, crystal structure and average crystallite size of the samples. Kinetics involved in phase formation has been discussed. Raman study showed a major band around 465 cm-1 in all the samples, which is attributed to the cubic fluorite structure of ceria. It was also found that for samples Ce0.9Ln0.1O1.95 (Ln = Nd, Sm, Gd) the frequency of F2g shifts to lower value. Electrochemical impedance spectroscopy has been used to measure the ionic conductivity of the samples at elevated temperatures. The Gd doped sample showed the highest grain boundary and total conductivity in comparison to Sm and Nd doped sample. Bulk thermal expansion behavior, sintered densities and micro structural features of the samples have also been studied.

  19. 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 investigators)

    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.

  20. Integrated four-channel Mach-Zehnder multi\\/demultiplexer fabricated with phosphorous doped SiO2 waveguides on Si

    Microsoft Academic Search

    B. H. Verbeek; C. H. Henry; N. A. Olsson; K. J. Orlowsky; R. F. Kazarinov; B. H. Johnson

    1988-01-01

    An analysis and the device performance of an integrated optical 4-channel multi\\/demultiplexer based on Mach-Zehnder interferometers elements are presented. The channel spacing is 77 Å. Single-mode channel waveguides are made from P-doped SiO2 core layers. Waveguide losses as low as 0.05 dB\\/cm and fiber-to-waveguide butt coupling as low as 0.5 dB for ?=1.5 ?m have been obtained. The multiplexer transfers

  1. 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.

  2. 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 future, the MEOS Miniature Earth Observing Satellite will innovatively combine remote atmospheric/land-cover measurements with ecosystem modelling in near real-time to obtain simultaneous variations in lower tropospheric GHG mixing ratios and the resulting responses of surface ecosystems. MEOS will provide lower tropospheric CO2 , CH4 , CO, N2 O, H2 O and aerosol mixing ratios over natural sources and sinks using two kinds of synergistic observations; a forward limb measurement and a follow-on nadir measurement over the same geographical tangent point. The measurements will be accomplished using separate limb and nadir suites of miniature lineimaging spectrometers and will be spatially coordinated such that the same air mass is observed in both views within a few minutes. The limb data will consist of 16-pixel vertical spectral line imaging to provide 2.5-km vertical resolution, while the corresponding nadir measurements will view sixteen 5 by 10 km2 ground pixels with a 160-km East-West swath width. The separate limb and nadir instrument suites each feature two complementary NIR miniature spectrometers that will operate in parallel, alternating the collected optical signal between the high-resolution Fabry-Perot guided-wave FP-IOSPEC spectrometer with simultaneous multiple microchannels at 0.03 FWHM with SNR>400 and the 1220 to 2450 nm broad-band spectrometer with 1.2 nm FWHM such that one undergoes the illuminated segment of the processing while the other spectrometer undergoes its dark signal processing. This spectral region provides several harmonic optical absorption bands associated with CO2 , CH4 , CO, H2 O and N2 O. The innovative data synergy of the coarse resolution broad-band spectra with the scanned spectral measurements of the trace-gas fine features at 0.03 nm FWHM in multiple microchannels will be used to improve the accuracy of the trace gas retrievals relative to current missions. In addition, the mission will retrieve cloud top pressures to better than ±0.1 kPa from measurements of the 0.76 mm O2 A band with 0.02 nm resolution and will conta

  3. 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

    The fascination of learning more about the way system Earth operates has driven generations of Earth scientists. This has been the case for early pioneers such as Arthur Holmes, focusing on the geological record in continental settings, as well as for the founding fathers of plate tectonics, who built upon the results of exploring the ocean floor. Two years ago we celebrated the centenary of the discovery by Mohorovicic of the seismic discontinuity that separates the crust from the mantle, which now carries his name. Reading the rocks and mapping the (sub)surface of the Earth has provided the foundation for a great deal of what we conceptually pursue today in developing and validating coupled deep Earth and surface processes. The unexpected is probably characterizing most of my scientific career. It started in 1968 when, as a student, entering the geology program of Groningen University headed by Professor Philip Kuenen, a pioneer in marine geology and sedimentology, the textbook of Arthur Holmes just happened to be my first purchase. It was during those years that plate tectonics drastically changed everything we were learning. I was also privileged to enter a few years later as an MSc student the Utrecht geophysics school at a time where Nico Vlaar as a young professor was developing a vigorous research program with a focus on seismology, attracting and stimulating many talented students. When he and Rinus Wortel started research on Tectonophysics in Utrecht, I decided to go for a PhD research project tackling the problem of the initiation of subduction, a first order problem in geodynamics, with still many aspects to be resolved. This research and the joint work with Rinus Wortel on modeling intraplate stresses in the Faralon, Nazca and Indo-Australian plates led quite unexpectedly to exploring, together with Kurt Lambeck, intraplate stress fluctuations in the lithosphere as possible tectonic causes for the origin of third-order cycles in relative sea-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 go. Not only on a national level, such as pursued by the Netherlands Research School of Integrate

  4. 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.

  5. 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.

  6. Early Earth

    NSDL National Science Digital Library

    The formative processes that shaped our planet offer up several exciting areas for teaching. How did the earth's solid crust evolve? What processes formed the initial atmosphere? How and where did life emerge? Each of these areas is interesting in its own right, but the formation and evolution of the earth as an integrated system is a concept that also has direct applications for teaching. This website offers a growing collection of teaching materials and research results that will aid in the understanding of and teaching about the early earth.

  7. The effect of Ce3+ ions on the spectral and decay characteristics of luminescence phosphate-borate glasses doped with rare-earth ions

    NASA Astrophysics Data System (ADS)

    Valiev, D. T.; Polisadova, E. F.; Belikov, K. N.; Egorova, N. L.

    2014-05-01

    The luminescent characteristics of Li2O-B2O3-P2O5-CaF2 (LBPC) glasses doped with Gd3+ and Tb3+ ions and codoped with Ce3+ are studied by pulsed optical spectrometry under electron beam excitation. It is found that in glass with Ce3+ and Gd3+ ions a decrease in the decay time of gadolinium luminescence in the 312-nm band (6 P J ? 8 S 7/2) was observed. It is shown that in the glass LBPC: Tb, Ce, an increase in the emission intensity in the main radiative transitions in terbium ion was observed. In the kinetics of luminescence band 545 nm of LBPC: Tb, Ce glasses, is present stage of buildup, the character of which changes with the doped of Ce3+ ions. The mechanism of energy transfer in LBP glasses doped with rare elements is discussed.

  8. Habitability of Super-Earth Planets around Main-Sequence Stars including Red Giant Branch Evolution: Models based on the Integrated System Approach

    Microsoft Academic Search

    M. Cuntz; W. von Bloh; K.-P. Schroeder; C. Bounama; S. Franck

    2011-01-01

    In a previous study published in Astrobiology, we focused on the evolution of habitability of a 10 M_E super-Earth planet orbiting a star akin to the Sun. This study was based on a concept of planetary habitability in accordance to the integrated system approach that describes the photosynthetic biomass production taking into account a variety of climatological, biogeochemical, and geodynamical

  9. INTEGRATING EARTH OBSERVATION AND FIELD DATA INTO A LYME DISEASE MODEL TO MAP AND PREDICT RISKS TO BIODIVERSITY AND HUMAN HEALTH

    EPA Science Inventory

    DW-75-92243901 Title: Integrating Earth Observation and Field Data into a Lyme Disease Model to Map and Predict Risks to Biodiversity and Human HealthDurland Fish, Maria Diuk-Wasser, Joe Roman, Yongtao Guan, Brad Lobitz, Rama Nemani, Joe Piesman, Montira J. Pongsiri, F...

  10. Analytical theory of Earth’s rotation

    Microsoft Academic Search

    V. A. Brumberg; T. V. Ivanova

    2009-01-01

    An analytical theory of the rotation of the rigid Earth is developed in a form compatible with the general planetary theory.\\u000a Numerical estimates of the constants of integration of the Poisson equations, which are a particular case of the equations\\u000a of the Earth’s rotation, are given.

  11. 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.

  12. Building Capacity to Integrate NASA Earth Science into Water Resources Management Applications in the Context of a Changing Climate

    NASA Astrophysics Data System (ADS)

    Prados, A. I.; Mehta, A. V.

    2011-12-01

    The NASA Applied Sciences program provides technical capacity building activities to enable decision-makers to integrate NASA Earth Science into environmental management activities. This includes workshops tailored to end-user needs by working directly with agencies to 1) identify environmental management activities that could benefit from NASA Earth Science and 2) conducting workshops that teach the NASA products and decision-support tools best suited to the identified application area. Building on a successful 3-year effort on air pollution monitoring for environmental applications, the project has expanded into water resources. Climate Change has dramatically increased demand for observational and predictive data in support of decision making activities related to water supply and demand. However, a gap remains between NASA products and applied research and the entities who stand to benefit from their utilization. To fill this gap, the project has developed short courses on 1) impacts of climate change on water resources 2) hands-on exercises on access and interpretation of NASA imagery relevant to water resources management via the use of decision-support web tools and software and 3) case studies on the application of NASA products in the field. The program is currently focused on two areas 1) precipitation products over the central and southern U.S. that help communities and agencies improve flooding forecasts and 2) snow and snow/water equivalent products over the western U.S and Latin America that can provide end-users with improved stream flow prediction in Spring within a framework of decreasing snow availability.

  13. 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.

  14. 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 inside salt deposits used by phototrophs for taking advantage of sheltering particular light wavelengths. These acidic salts deposits located in Río Tinto shelter life forms that are difficult to visualize by eye. This interdisciplinary field analogue campaign was conducted in the framework of the CAREX FP7 EC programme.

  15. 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 diverse research opportunities that are inspired by views of Earth from space taken by astronauts on board the International Space Station. The interest and connection to viewing our home planet from space will inevitably spark questions that will drive students to pursue their research investigations, as well as forming a basis for comparisons to the exploration of other planetary bodies in our solar system.

  16. Photoinduced phenomena in chalcogenide glasses doped with metals

    E-print Network

    Boolchand, Punit

    on relaxation of photodarkening in a-As2Se3 doped with Sn and rare-earth (RE) ions (Dy, Pr, Hon, Sm3 Nd, Er3 for chalcogenide glasses doped with rare-earth ions as perspective materials for fibre optics amplifiers operating and the kinetics ofphotodarkening in amonhous As2Se3:Sn thin films at %) and and AsSe3 doped with rare-earth ions

  17. A net-centric system of services model for the Integrated Earth Observation System (IEOS) and the Integrated Ocean Observing System (IOOS)

    NASA Astrophysics Data System (ADS)

    Ardanuy, Philip; Bensman, Ed; Bergen, Bill; Chen, Bob; Griffith, Frank; Sutton, Cary; Hood, Carroll; Ritchie, Adrian; Tarro, Andre

    2006-08-01

    This paper considers an evolved technique for significantly enhanced enterprise-level data processing, reprocessing, archival, dissemination, and utilization. There is today a robust working paradigm established with the Advanced Weather Interactive Processing System (AWIPS)-NOAA/NWS's information integration and fusion capability. This process model extends vertically, and seamlessly, from environmental sensing through the direct delivery of societal benefit. NWS, via AWIPS, is the primary source of weather forecast and warning information in the nation. AWIPS is the tested and proven "the nerve center of operations" at all 122 NWS Weather Forecast Offices (WFOs) and 13 River Forecast Centers (RFCs). However, additional line organizations whose role in satisfying NOAA's five mission goals (ecosystems, climate, weather & water, commerce & transportation, and mission support) in multiple program areas might be facilitated through utilization of AWIPS-like functionalities, including the National Marine Fisheries Service (NMFS); National Environmental Satellite, Data, and Information Service (NESDIS); Office of Oceanic & Atmospheric Research (OAR); and the National Ocean Service (NOS). In addition to NOAA's mission goals, there are nine diverse, recommended, and important societal benefit areas in the US Integrated Earth Observation System (IEOS). This paper shows how the satisfaction of this suite of goals and benefit areas can be optimized by leveraging several key ingredients: (1) the evolution of AWIPS towards a net-centric system of services concept of operations; (2) infusion of technologies and concepts from pathfinder systems; (3) the development of new observing systems targeted at deliberate, and not just serendipitous, societal benefit; and (4) the diverse, nested local, regional, national, and international scales of the different benefits and goal areas, and their interoperability and interplay across the system of systems.

  18. 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, protocols and practices increases the number of stake holders with an interest in supporting the system.

  19. 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

    The objectives of conservation have been focused ever more intensively for two decades on the preservation of "biodiversity." Emphasis has been on the losses of species through extinction. The cure has been the establishment of parks and reserves to protect "hot spots," especially in the tropics, where the diversity of species is high. The efforts in preservation have often extended to the development of connecting links among reserves to allow movements among them. The approach has been codified in law in the form of the Endangered Species Act in the United States and the Biodiversity Treaty, both of which address the issue species by species and each of which has obvious weaknesses. Such efforts may be appropriate but they are totally inadequate as the sum of activities in conservation in a world of 6 billion people with exploding technologies for exploiting virtually all of the earth for immediate human benefit. The biosphere is decaying rapidly as a habitat for all life, including people, not because of the extinction of species, but because of the progressive impoverishment of natural communities through human-induced chronic disruption that is now global and ubiquitous. The improverishment leads to progressive environmental dysfunction that is cumulative, but only in its later stages leads to extinction of species. Long before extinction becomes important, genetically distinct, local ecotypes are lost and the natural communities in which they were developed become improverished and dysfunctional. The most conspicuous disruption is that of climate, a global change in the environment of every ecosystem. The most elaborate and carefully interlinked array of natural reserves will succumb as climate is moved out from under them... and biodiversity will suffer the very extinctions the parks were established to avoid. But long before that, the human environment will suffer conspicuous and progressive impoverishment. The objective of conservation is the preservation 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

  20. 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 satellite data would be utilized within a geobrowser in a near real-time setting, we present a demonstration from the 2007 hurricane season, developed within the Google Earth framework. A menu of imagery based sequential satellite overpasses (GOES and other geostationary satellites, TRMM, CloudSat, Terra, Aqua, DMSP, NOAA, QuikScat) during the storm lifecycle, are presented to the Earth client in an structured folder format. The remapping of these satellite data follows the hurricane track, enabling the user to view, animate, zoom, overlay and combine visible, infrared and passive microwave imagery and combine with other data (surface reports, forecasts, surface winds, ground and spaceborne radars, etc.) at various stages of the hurricane lifecycle. Pop-up balloons provide training that explains the properties and capabilities of the satellite datasets and what components of the underlying weather are represented. Future satellite overpass tracks are provided so that the user can anticipate imagery updates several days in advance (e.g., as a hurricane approaches landfall). This combination of geo-navigable data provides a convenient framework for efficiently demonstrating meteorological, oceanographic and weather and climate concepts to students, planners, and the public at large.

  1. Synthesis, structure and X-ray excited luminescence of Ce{sup 3+}-doped AREP{sub 2}O{sub 7}-type alkali rare earth diphosphates (A=Na, K, Rb, Cs; RE=Y, Lu)

    SciTech Connect

    Yuan Junlin [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Graduate School of Chinese Academy of Sciences, Beijing (China); Zhang Hui; Chen Haohong; Yang Xinxin [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhao Jingtai [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)], E-mail: jtzhao@mail.sic.ac.cn; Gu, Mu [Tongji University, Shanghai 200020 (China)

    2007-12-15

    The crystal structures of five new alkali rare earth diphosphates were obtained by Rietveld refinement of powder X-ray diffraction (XRD) profiles, including four alkali lutetium diphosphates ALuP{sub 2}O{sub 7} (A=Na, K, Rb, Cs) and the low temperature phase of KYP{sub 2}O{sub 7}. The scintillation properties of Ce{sup 3+}-doped AREP{sub 2}O{sub 7} (A=Na, K, Rb, Cs; RE=Y, Lu) powder samples were studied under static and pulsed X-ray excitations, and featured outstanding scintillation properties with light yields 1-2 times of that of Bi{sub 4}(GeO{sub 4}){sub 3} and relatively short decay time of 20-28 ns. Considering the suitable emission wavelength range, large light yield, short decay time, and non-hygroscopic nature, Ce{sup 3+}-doped AREP{sub 2}O{sub 7}-type alkali rare earth diphosphates are potential candidates for high-counting-rate scintillation applications. - Graphical abstract: The perspective view of KLuP{sub 2}O{sub 7} unit cell. The crystal structures of five AREP{sub 2}O{sub 7} diphosphates were obtained from Rietveld refinement. Under the excitation of hard X-ray, the Ce{sup 3+}-activated AREP{sub 2}O{sub 7} (A=Na-Cs; RE=Y, Lu) feature strong Ce{sup 3+} 5d-4f emission with high light yield (1-2 times of that of Bi{sub 4}Ge{sub 3}O{sub 12}) and fast decay time within 20-28 ns.

  2. carleton.ca Earth Sciences

    E-print Network

    Dawson, Jeff W.

    carleton.ca Earth Sciences #12;Earth is our home. It is a dynamic planet, integrating and recording spectrometers or electron microprobes--earth scientists investigate Earth's evolution to help understand future today and for the future is enhanced by the expertise of economic geologists. Knowledge of the Earth

  3. Design, Development, and Evaluation of an Integrated Mathematics and Science Course to Teach Earth System Science to Preservice Middle School Teachers

    NASA Astrophysics Data System (ADS)

    Adams, P.; Heinrichs, J.

    2007-12-01

    Pre-service middle school teachers receive a mixed representation of science during their university education. Science disciplines and mathematics are taught with little attention to integration. Earth system science is seldom presented. Fort Hays State University (FHSU) has addressed this issue through the development of an Integrated Mathematics and Science Course (development partially supported through National Science Foundation's CCLI Program under DUE#0088818 and DUE#0311042). The course was designed by an interdisciplinary team using a "cycles-of-nature" theme to integrate across earth and space science, physics, chemistry, biology, and mathematics. Several of the themes were earth system science based (e.g. Climate Cycles, Seasonal Cycles, Geophysical Cycles). The course also incorporated statistical analysis of data, estimations, and reading scientific literature. To promote pre-service teachers abilities to do authentic science, six to eight weeks of the fifteen week course were utilized for the preservice teachers to design, conduct, and present a self-designed research project based on the content of the course. Evaluation data from the course indicated that it was successful in a) changing university faculty perceptions of teaching science, b) illustrating novel approaches to preservice teachers, c) improving an understanding of the nature of science in preservice teachers, and d) increasing the preservice teachers understanding of the integrated nature of science.

  4. Superconductivity and phase diagram in iron-based arsenic-oxides ReFeAsO1?? (Re = rare-earth metal) without fluorine doping

    Microsoft Academic Search

    Zhi-An Ren; Guang-Can Che; Xiao-Li Dong; Jie Yang; Wei Lu; Wei Yi; Xiao-Li Shen; Zheng-Cai Li; Li-Ling Sun; Fang Zhou; Zhong-Xian Zhao

    2008-01-01

    Here we report a new class of superconductors prepared by high-pressure synthesis in the quaternary family ReFeAsO1?? (Re=Sm, Nd, Pr, Ce, La) without fluorine doping. The onset superconducting critical temperature (Tc) in these compounds increases with the reduction of the Re atom size, and the highest Tc obtained so far is 55 K in SmFeAsO1??. For the NdFeAsO1?? compound with

  5. The inner filter effect of Cr(VI) on Tb-doped layered rare earth hydroxychlorides: new fluorescent adsorbents for the simple detection of Cr(VI).

    PubMed

    Kim, Hyunsub; Lee, Byung-Il; Byeon, Song-Ho

    2015-01-14

    Terbium-doped layered yttrium hydroxychlorides (LYH:xTb) were explored for the simple and convenient detection of Cr(VI) in aqueous solution, where the effective overlap of excitation bands of LYH:xTb with absorption bands of Cr(VI) constructs a new inner filter effect system. The shielding of excitation light for LYH:xTb by adsorbed Cr(VI) was so effective that a feasible detection sensitivity could be achieved. PMID:25417807

  6. 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.

  7. Optimization of an integrated optic broadband duplexer for 0.8\\/1.3-micrometer applications

    Microsoft Academic Search

    Elise Ghibaudo; Jean-Emmanuel Broquin; Pierre Benech

    2003-01-01

    These last years, the growth of data traffic has increased the interest for broadband integrated optic devices. Their applications include, for example, the fiber communications on a single fiber by adding the transmission capacity of two optical telecommunication windows for Local Area Networks (LAN) and Wide Area Networks (WAN) or by combining pump and signal wavelenghts in rare earth doped

  8. Earth materials and earth dynamics

    SciTech Connect

    Bennett, K; Shankland, T. [and others

    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).

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

    Microsoft Academic Search

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

    2010-01-01

    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

  10. 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.

  11. Constructing one-dimensional silver nanowire-doped reduced graphene oxide integrated with CdS nanowire network hybrid structures toward artificial photosynthesis

    NASA Astrophysics Data System (ADS)

    Liu, Siqi; Weng, Bo; Tang, Zi-Rong; Xu, Yi-Jun

    2014-12-01

    A ternary hybrid structure of one-dimensional (1D) silver nanowire-doped reduced graphene oxide (RGO) integrated with a CdS nanowire (NW) network has been fabricated via a simple electrostatic self-assembly method followed by a hydrothermal reduction process. The electrical conductivity of RGO can be significantly enhanced by opening up new conduction channels by bridging the high resistance grain-boundaries (HGBs) with 1D Ag nanowires, which results in a prolonged lifetime of photo-generated charge carriers excited from the CdS NW network, thus making Ag NW-RGO an efficient co-catalyst with the CdS NW network toward artificial photosynthesis.A ternary hybrid structure of one-dimensional (1D) silver nanowire-doped reduced graphene oxide (RGO) integrated with a CdS nanowire (NW) network has been fabricated via a simple electrostatic self-assembly method followed by a hydrothermal reduction process. The electrical conductivity of RGO can be significantly enhanced by opening up new conduction channels by bridging the high resistance grain-boundaries (HGBs) with 1D Ag nanowires, which results in a prolonged lifetime of photo-generated charge carriers excited from the CdS NW network, thus making Ag NW-RGO an efficient co-catalyst with the CdS NW network toward artificial photosynthesis. Electronic supplementary information (ESI) available: Experimental details, photographs of the experimental setups for photocatalytic activity testing, SEM images of Ag NWs and CdS NWs, Zeta potential, Raman spectra, DRS spectra, PL spectra and PL decay time evolution, and photocatalytic performances of samples for reduction of 4-NA and recycling test. See DOI: 10.1039/c4nr04229h

  12. INTEGRAL observations of the cosmic X-ray background in the 5-100 keV range via occultation by the Earth

    E-print Network

    E. Churazov; R. Sunyaev; M. Revnivtsev; S. Sazonov; S. Molkov; S. Grebenev; C. Winkler; A. Parmar; A. Bazzano; M. Falanga; A. Gros; F. Lebrun; L. Natalucci; P. Ubertini; J. -P. Roques; L. Bouchet; E. Jourdain; J. Knoedlseder; R. Diehl; C. Budtz-Jorgensen; S. Brandt; N. Lund; N. J. Westergaard; A. Neronov; M. Turler; M. Chernyakova; R. Walter; N. Produit; N. Mowlavi; J. M. Mas-Hesse; A. Domingo; N. Gehrels; E. Kuulkers; P. Kretschmar; M. Schmidt

    2007-02-12

    We study the spectrum of the cosmic X-ray background (CXB) in energy range $\\sim$5-100 keV. Early in 2006 the INTEGRAL observatory performed a series of four 30ksec observations with the Earth disk crossing the field of view of the instruments. The modulation of the aperture flux due to occultation of extragalactic objects by the Earth disk was used to obtain the spectrum of the Cosmic X-ray Background(CXB). Various sources of contamination were evaluated, including compact sources, Galactic Ridge emission, CXB reflection by the Earth atmosphere, cosmic ray induced emission by the Earth atmosphere and the Earth auroral emission. The spectrum of the cosmic X-ray background in the energy band 5-100 keV is obtained. The shape of the spectrum is consistent with that obtained previously by the HEAO-1 observatory, while the normalization is $\\sim$10% higher. This difference in normalization can (at least partly) be traced to the different assumptions on the absolute flux from the Crab Nebulae. The increase relative to the earlier adopted value of the absolute flux of the CXB near the energy of maximum luminosity (20-50 keV) has direct implications for the energy release of supermassive black holes in the Universe and their growth at the epoch of the CXB origin.

  13. 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 .

  14. Synthesis and characterization of polymer composite base on RE3+:Al2O3 nanopowders doped by rare earth metals for application in optoelectronics

    NASA Astrophysics Data System (ADS)

    Polis, P.; Jastrzebska, A.; Jureczko, J.; Jusza, A.; Piramidowicz, R.; Anders, K.; Olszyna, A.; Kunicki, A.; Fabianowski, W.

    2013-07-01

    In this work we report the recent results of our investigations on synthesis the PMMA composite base on Al2O3 doped by ytterbium metal. The set of the Al2O3:Yb3+ composite samples was manufactured and examined with respect of their structural, physical and mechanical properties. The investigations have confirmed applicability of developed synthesis method to manufacturing of good structural quality, decent level of agglomeration, good homogeneity and good thermal stability consisting of nanoparticles with average size in the range of several tens of nanometers.

  15. Magnetic nanoparticles-doped silica layer reported on ion-exchanged glass waveguide: towards integrated magneto-optical devices

    Microsoft Academic Search

    Hadi Amata; François Royer; Fadi Choueikani; Damien Jamon; Jean-Emmanuel Broquin; Jean Claude Plenet; Jean Jaques Rousseau

    2010-01-01

    In the framework of optical telecommunication systems, many functions are integrated on the same substrate. Nevertheless, one of the most important, such as isolation, is achieved using discrete components. It is based on magnetic materials which are always difficult to integrate with classical technologies. This is due to the annealing temperature of magnetic materials. In this paper we present another

  16. 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.

  17. 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 nutrient and cross-shelf sediment transport around the shelf/slope break and through the canyon to the deep sea. There and north along the mid-continental slope, instruments on exposed and shallowly buried gas hydrates allow monitoring of changes in their distribution, structure, and venting, particularly related to earthquakes, slope failures and regional plate motions. Circulation obviation retrofit kits (CORKs) at mid-plate ODP 1026-7 monitor real-time changes in crustal temperature and pressure, particularly as they relate to events such as earthquakes, hydrothermal convection or regional plate strain. At Endeavour Ridge, complex interactions among volcanic, tectonic, hydrothermal and biological processes are quantified at the western edge of the Juan de Fuca plate. Across the network, high resolution seismic information elucidates tectonic processes such as earthquakes, and a tsunami system allows determination of open ocean tsunami amplitude, propagation direction, and speed. The infrastructure has further capacity for experiments to expand from this initial suite. Further information and opportunities can be found at http://www.neptunecanada.ca

  18. Nanoparticle doping process for improved fibre amplifiers and lasers

    Microsoft Academic Search

    A. Pastouret; C. Gonnet; C. Collet; O. Cavani; E. Burov; C. Chaneac; A. Carton; J. P. Jolivet

    2009-01-01

    Manufacture fiber amplifiers and lasers in a versatile and cost effective way while controlling rare-earths chemical environment becomes a real technology differentiator. A MCVD compatible Nanoparticle Doping Process has been developed to master with a higher accuracy rare earth amplifier and ytterbium laser fibers. Improved doped erbium fibers with C-band gain shape were obtained with much less aluminum content and

  19. UNIVERSITY of CALIFORNIA EFFECT OF BISMUTH DOPING ON THE MAGNETIC PROPERTIES

    E-print Network

    Belanger, David P.

    UNIVERSITY of CALIFORNIA SANTA CRUZ EFFECT OF BISMUTH DOPING ON THE MAGNETIC PROPERTIES OF RARE of Bismuth Doping on the Magnetic Properties of Rare-Earth Orthoferrites by Kelsey A. Collier The purpose of this experiment was to investigate the magnetic properties of bismuth-doped rare-earth orthoferrites, prompted

  20. Erbium-doped nanoparticles in silica-based optical Wilfried Blanc*, Valrie Mauroy, Bernard

    E-print Network

    Boyer, Edmond

    Erbium-doped nanoparticles in silica-based optical fibres Wilfried Blanc*, Valérie Mauroy, Bernard.dussardier@unice.fr *Corresponding author Abstract: Developing of new rare-earth (RE)-doped optical fibres for power amplifiers potentials in improving rare-earth doped fibre amplifiers and laser sources. Keywords: Optical fibres, Erbium

  1. Effect of Mn doping on structural and magnetic susceptibility of C-type rare earth nano oxides Er{sub 2?x}Mn{sub x}O{sub 3}

    SciTech Connect

    Heiba, Zein K. [Ain Shams University, Faculty of Science, Physics Department, Cairo (Egypt) [Ain Shams University, Faculty of Science, Physics Department, Cairo (Egypt); Taif University, Faculty of Science, Physics Department (Saudi Arabia); Mohamed, Mohamed Bakr, E-mail: mbm1977@yahoo.com [Ain Shams University, Faculty of Science, Physics Department, Cairo (Egypt); Fuess, H. [Materials Science, Darmstadt University of Technology, D-64289 Darmstadt (Germany)] [Materials Science, Darmstadt University of Technology, D-64289 Darmstadt (Germany)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ? Er{sub 2?x}Mn{sub x}·O{sub 3} (0.0 ? x ? 0.20) prepared by sol–gel method. ? The change in lattice parameter is not linear with x due to the change in crystallite size with doping. ? Anomalous concentration dependence is found in magnetic susceptibility. ? The effective magnetic moment ?{sub eff} is found to decrease with composition parameter x. ? Superexchange interactions between Er ions depending on the amount of Mn or Er in different sites. -- Abstract: The manganese doped rare earth oxides Er{sub 2?x}Mn{sub x} O{sub 3} (0.0 ? x ? 0.20) were synthesized by a sol–gel process and analyzed by X-ray diffraction using Rietveld refinement methods. A single phase solid solution is formed up to x = 0.15 while for x ? 0.2 a manganese oxide phase appears in the diffraction pattern. Preferential cationic distribution between the non-equivalent sites 8b and 24d of space group Ia3{sup ¯} is found for all samples but to a different extent. The octahedral volume and average bond length of Er{sub 1}-O for 8b site decrease while both octahedral volume and bond length of Er{sub 2}-O for 24d site increase. Magnetization measurements were done in the temperature range 5–300 K. The effective magnetic moment ?{sub eff} is found to decrease with composition parameter x, except for sample x = 0.05 where the magnetization is enhanced. The Curie-Weiss paramagnetic temperatures indicate antiferromagnetic interaction.

  2. Incubational domain characterization in lightly doped ceria

    SciTech Connect

    Li Zhipeng, E-mail: Zhipeng@email.unc.edu [Global Research Center for Environment and Energy based on Nanomaterials Science, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599 (United States); Mori, Toshiyuki [Global Research Center for Environment and Energy based on Nanomaterials Science, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); John Auchterlonie, Graeme [Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, Brisbane, QLD 4072 (Australia); Zou Jin [Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, Brisbane, QLD 4072 (Australia); Division of Materials, University of Queensland, St. Lucia, Brisbane, QLD 4072 (Australia); Drennan, John [Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, Brisbane, QLD 4072 (Australia)

    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.

  3. 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, ?, is remarkably low for the Tb-doped nanoparticles, with ? = 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.

  4. 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 underestimates emissions substantially, for historical times by about 40%. Implementation of land management such as gross transitions is a step forward in terms of comprehensiveness of simulated processes. However, it has increased model spread in carbon fluxes, because land management processes have been considered by only a subset of recent ESMs contributing to major projects such as IPCC or the Global Carbon Project. This model spread still causes the net land use flux to be the most uncertain component in the global carbon budget. Other causes have previously been identified as differences in land use datasets, differing types of vegetation model, accounting of nutrient limitation, the inclusion of land use feedbacks (increase in atmospheric CO2 due to land use emissions causing terrestrial carbon uptake), and a confusion of whether the net land use flux in ESMs should be reported as instantaneous emissions, or also account for delayed carbon responses and regrowth. These differences explain a factor 2-6 difference between model estimates and are expected to be further affected by interactions with land management. This highlights the importance of an accurate protocol for future model intercomparisons of carbon fluxes from land cover change and land management to ensure comparison of the same processes and fluxes.

  5. EarthLabs: Teacher's Guide

    NSDL National Science Digital Library

    The EarthLabs project provides a national model for rigorous and engaging Earth and environmental science labs. The activities in each EarthLabs topic represent a lab sequence for an integrated instructional unit. Six topics are available: corals, cryosphere, drought, earth system science, fisheries and hurricanes. There are six to nine labs within each topic with complete directions.

  6. 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.

  7. EarthLabs

    NSDL National Science Digital Library

    EarthLabs is a collection of challenging, lab-based high school Earth science curriculum units, each of which integrates text, hands-on activities, interactive visualizations, video, authentic science data, and data visualization and analysis tools. Each unit highlights the interconnectedness and complexities of the Earth system in the context of a specific content area (including Earth system science, climate, weather, atmosphere, cryosphere, environmental science, hurricanes, drought, fisheries, oceans, carbon cycle), and can be integrated into an existing Earth or environmental science course or used as an independent curriculum unit. In addition to the student portal, EarthLabs provides a separate teacher's guide ("EarthLabs for Educators") that provides background and logistical information, pedagogical guidance, and answers to assessments embedded in the student portal.

  8. Influence of Ga doping on rare earth moment ordering and ferromagnetic transition in Nd0.7Sr0.3Co1-xGaxO3

    NASA Astrophysics Data System (ADS)

    Kumar, Pawan; Maheswar Repaka, D. V.; Aparnadevi, M.; Tripathi, T. S.; Mahendiran, R.

    2013-05-01

    We report the impact of dilution of Co sublattice by non-magnetic Ga3+ ion on the magnetic, electrical, and magnetoresistive properties in Nd0.7Sr0.3Co1-xGaxO3 for x = 0-0.12. Field-cooled magnetization of the parent compound (x = 0) shows an anomalous maximum at T* = 54.6 K much below the onset of ferromagnetic transition (TC = 160 K) of the Co sublattice, which is attributed to the polarization of Nd-4f moments antiparallel to the Co-3d sublattice. Both TC and T* shift to low temperature with increasing x and the Nd-4f spin reverses from antiparallel to parallel with increasing strength of the magnetic field. While the value of high field magnetization is not seriously affected by Ga doping, coercive field at 10 K increases dramatically with increasing x. Ga substitution transforms ferromagnetic metallic state into ferromagnetic insulating state for x ? 0.03 and decreases the magnitude of magnetoresistance from 6% for x = 0% to 0.5% for x = 0.12.

  9. 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 additional content course within a science discipline that is concurrently taught with a science methods course. Emphasizing inquiry-based activities, these bridge courses also focus on developing integrated understandings of the sciences. The continuum extends beyond the student teaching experience by tracking cohorts of science teachers during their in-service years. With funding from the National Science Foundation's Teacher Professional Continuum program, we are conducting research on this inquiry-based professional development approach for K-8 teachers across this continuum.

  10. Modeling of optical amplifier waveguide based on silicon nanostructures and rare earth ions doped silica matrix gain media by a finite-difference time-domain method: comparison of achievable gain with Er3+ or Nd3+ ions dopants

    E-print Network

    Cardin, Julien; Dufour, Christian; Gourbilleau, Fabrice

    2015-01-01

    A comparative study of the gain achievement is performed in a waveguide optical amplifier whose active layer is constituted by a silica matrix containing silicon nanograins acting as sensitizer of either neodymium ions (Nd 3+) or erbium ions (Er 3+). Due to the large difference between population levels characteristic times (ms) and finite-difference time step (10 --17 s), the conventional auxiliary differential equation and finite-difference time-domain (ADE-FDTD) method is not appropriate to treat such systems. Consequently, a new two loops algorithm based on ADE-FDTD method is presented in order to model this waveguide optical amplifier. We investigate the steady states regime of both rare earth ions and silicon nanograins levels populations as well as the electromagnetic field for different pumping powers ranging from 1 to 10 4 mW.mm-2. Furthermore, the three dimensional distribution of achievable gain per unit length has been estimated in this pumping range. The Nd 3+ doped waveguide shows a higher gross...

  11. Performance characterization of new erbium-doped fibers using MCVD nanoparticle doping process

    Microsoft Academic Search

    David Boivin; Alain Pastouret; Ekaterina Burov; Cédric Gonnet; Olivier Cavani; Simon Lempereur; Pierre Sillard

    2011-01-01

    In 2009, we introduced a new doping concept involving Al2O3\\/rare-earth nanoparticles (NP) in a MCVD-compatible process finding potential applications in Erbium-, Ytterbium- or Erbium-Ytterbium-doped fiber amplifiers and lasers.1 This approach, motivated by the need for increased efficiencies and improved attributes, is characterized by the ability to control the rare-earth ion environment independently from the core composition. The NP matrix can

  12. 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-yAlxDy yN (x=0.10, 0.30, y=0.01) powders were synthesized using the solution method while incorporating a stainless steel pressure vessel, which increased the synthesis pressure and aided the formation of a single phase hydroxide precursor. This in turn produced a single phase alloy nitride in the final step. Dy3+ emission that was not observed in GaN powders was also observed in the Ga1-x-yAlxDyyN powder. This suggested that the incorporation of aluminum enabled rare-earth emission in the nitrides synthesized for these experiments. However, attempts to sputter nitride alloy thin films via radio frequency sputtering were unsuccessful; only very minor peak shifts in the X-ray diffraction patterns were observed. Nevertheless, energy dispersive X-ray spectroscopy indicates the presence of Al in the Ga0.5Al0.5N film deposited on a Si substrate. This suggested that Al atoms may have segregated from the alloy lattice during the deposition process, with only a small amount of Al atoms incorporated into the GaN lattice.

  13. Project Earth Science: Astronomy

    NSDL National Science Digital Library

    P. Sean Smith

    2001-01-01

    The hands-on, teacher-tested activities in Project Earth Science: Astronomy brings the sometimes daunting concepts of astronomy down to Earth. Background information, supplementary readings, and suggestions for integrating other disciplines provide the teacher with a framework to launch a successful introduction to astronomy. Students will discover Earth's uniqueness by examining it as a part of the whole--one planet within our Solar System. How did the planets form? Are we seeing a star's present or past? Why is Earth's distance from the Sun so important? Project Earth Science: Astronomy will lead you and your students on an exploration that takes you to the stars and back.

  14. 3D Cavity quantum electrodynamics with a rare-earth spin ensemble

    E-print Network

    S. Probst; A. Tkalcec; H. Rotzinger; D. Rieger; J-M. Le Floch; M. Goryachev; M. E. Tobar; A. V. Ustinov; P. A. Bushev

    2014-06-13

    We present cavity QED experiments with an Er:YSO crystal magnetically coupled to a 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 Er$^{3+}$ 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.

  15. Earth Institute

    NSDL National Science Digital Library

    The mission of the Earth Institute at Columbia University is to help the world achieve sustainability by expanding understanding of the Earth as one integrated system. Through research, education, and the practical application of research to real-world challenges, the Institute addresses nine interconnected global issues: climate and society, water, energy, poverty, ecosystems, public health, food and nutrition, and hazards and urbanization. The Institute's site offers a collection of videotaped events, including the biannual "State of the Planet" conferences, 2002-08, a Distinguished Lecture series, and the Sustainable Development seminar series, as well as e-seminars and e-briefings, information about funding opportunities, and information about educational opportunities at Columbia.

  16. Multimodal bioimaging using rare earth doped Gd2O2S: Yb/Er phosphor with upconversion luminescence and magnetic resonance properties

    PubMed Central

    Ajithkumar, G.; Yoo, Benjamin; Goral, Dara E.; Hornsby, Peter J.; Lin, Ai-Ling; Ladiwala, Uma; Dravid, Vinayak P.; Sardar, Dhiraj K

    2013-01-01

    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. PMID:25191618

  17. 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. PMID:25191618

  18. Earth as a System

    NSDL National Science Digital Library

    WGBH/Boston

    This short video uses animated imagery from satellite remote sensing systems to illustrate that Earth is a complex, evolving body characterized by ceaseless change. Adapted from NASA, this visualization helps explain why understanding Earth as an integrated system of components and processes is essential to science education.

  19. 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.

  20. A net-centric system of services model for the Integrated Earth Observation System (IEOS) and the Integrated Ocean Observing System (IOOS)

    Microsoft Academic Search

    Philip Ardanuy; Ed Bensman; Bill Bergen; Bob Chen; Frank Griffith; Cary Sutton; Carroll Hood; Adrian Ritchie; Andre Tarro

    2006-01-01

    This paper considers an evolved technique for significantly enhanced enterprise-level data processing, reprocessing, archival, dissemination, and utilization. There is today a robust working paradigm established with the Advanced Weather Interactive Processing System (AWIPS)-NOAA\\/NWS's information integration and fusion capability. This process model extends vertically, and seamlessly, from environmental sensing through the direct delivery of societal benefit. NWS, via AWIPS, is the

  1. 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

  2. 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 water availability.

  3. 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.

  4. Use of geochemical signatures, including rare earth elements, in mosses and lichens to assess spatial integration and the influence of forest environment

    NASA Astrophysics Data System (ADS)

    Gandois, L.; Agnan, Y.; Leblond, S.; Séjalon-Delmas, N.; Le Roux, G.; Probst, A.

    2014-10-01

    In order to assess the influence of local environment and spatial integration of Trace Metals (TM) by biomonitors, Al, As, Cd, Cr, Cs, Cu, Fe, Mn, Ni, Pb, Sb, Sn, V and Zn and some rare earth element (REE) concentrations have been measured in lichens and mosses collected in three French forest sites located in three distinct mountainous areas, as well as in the local soil and bedrock, and in both bulk deposition (BD) and throughfall (TF). Similar enrichment factors (EF) were calculated using lichens and mosses and local bedrock for most elements, except for Cs, Mn, Ni, Pb, and Cu which were significantly (KW, p < 0.05) more enriched in mosses. Similar REE ratios were measured in soils, bedrock, lichens and mosses at each study sites, indicating a regional integration of atmospheric deposition by both biomonitors. Both TM signature and REE composition of mosses revealed that this biomonitor is highly influenced by throughfall composition, and reflect atmospheric deposition interaction with the forest canopy. This explained the higher enrichment measured in mosses for elements which concentration in deposition were influenced by the canopy, either due to leaching (Mn), direct uptake (Ni), or dry deposition dissolution (Pb, Cu, Cs).

  5. Earth's Atmosphere

    NSDL National Science Digital Library

    2012-08-03

    This problem set is about the methods scientists use to compare the abundance of the different elements in Earth's atmosphere. Answer key is provided. This is part of Earth Math: A Brief Mathematical Guide to Earth Science and Climate Change.

  6. Earth's Three

    E-print Network

    Hacker, Randi

    2010-11-17

    Broadcast Transcript: From Mongolia, land of fermented mare's milk, comes this beguiling morsel of nomadic oral tradition. It's called yertonciin gorav or Earth's Three. Earth's three what? Well, Earth's three top things in a number of categories...

  7. Spectroscopic characterization of Europium and Praseodymium doped Gallium Nitride powders

    Microsoft Academic Search

    Ei Brown; Olusola Oyebola; Uwe Hommerich; Takahiro Yamada; Hiroshi Nanbu; Hisanori Yamane; Kenji Kohiro; Yoshihiko Tsichida; John Zavada

    2008-01-01

    Rare earth (RE) doped GaN continues to be of interest for applications in display technology, solid-state light sources, and optical communications. Recently, RE doped GaN powders have been prepared using different methods including flux techniques and combustion synthesis. In this work, we report on the luminescent properties of Eu^3+ and Pr^3+ doped GaN powder prepared by a Na flux method

  8. Rare-earth aluminates as a charge trapping materials for NAND flash memories: Integration and electrical evaluation

    NASA Astrophysics Data System (ADS)

    Suhane, A.; Cacciato, A.; Richard, O.; Arreghini, A.; Adelmann, C.; Swerts, J.; Rothschild, O.; Van den bosch, G.; Breuil, L.; Bender, H.; Jurczak, M.; Debusschere, I.; Kittl, J. A.; De Meyer, K.; Van Houdt, J.

    2011-11-01

    In this paper, we provide evaluation of memory stacks with La, Lu and Gd aluminates as charge trapping materials. Critical integration issues are pointed out, particularly the mixing of these materials with adjacent layers. It is found that, in order to control the mixing of the aluminates with the tunnel oxide, nitride (for Gd) or nitride + oxide (for La and Lu) buffer layers have to be used. The nitride buffer layer, however, mixes with the tunnel oxide during stack fabrication. This results in very good erase and endurance performance, which is attributed to enhanced hole tunneling from the Si substrate, but degrades the retention performance.

  9. Earth Sciences Environmental Earth Sciences,

    E-print Network

    Brierley, Andrew

    94 Earth Sciences­ Environmental Earth Sciences, Geology Degree options MGeol (Single Honours Degrees) Earth Sciences BSc (Single Honours Degrees) Environmental Earth Sciences Geology BSc (Joint placement. * The Geology and Environmental Earth Sciences degrees are accredited by the Geological Society

  10. Earth Sciences Environmental Earth Sciences,

    E-print Network

    Brierley, Andrew

    84 Earth Sciences­ Environmental Earth Sciences, Geology MGeol (Single Honours Degrees) Earth Sciences BSc (Single Honours Degrees) Environmental Earth Sciences Geology BSc (Joint Honours Degrees) and among the most research-intensive in Europe. Features * The Department of Earth and Environmental

  11. 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.

  12. Erbium-doped transparent glass ceramic optical Characterization using mass spectroscopy and molecular dynamics modeling.

    E-print Network

    Boyer, Edmond

    Erbium-doped transparent glass ceramic optical fibres: Characterization using mass spectroscopy) doped silica-based optical fibres with transparent glass ceramic (TGC) core were fabricated through amplifiers and laser sources. Keywordst; Optical fibres, Rare-earth-doped materials; Silica; Spectroscopy

  13. A stand-alone tree demography and landscape structure module for Earth system models: integration with global forest data

    NASA Astrophysics Data System (ADS)

    Haverd, V.; Smith, B.; Nieradzik, L. P.; Briggs, P. R.

    2014-02-01

    Poorly constrained rates of biomass turnover are a key limitation of Earth system models (ESM). In light of this, we recently proposed a new approach encoded in a model called Populations-Order-Physiology (POP), for the simulation of woody ecosystem stand dynamics, demography and disturbance-mediated heterogeneity. POP is suitable for continental to global applications and designed for coupling to the terrestrial ecosystem component of any ESM. POP bridges the gap between first generation Dynamic Vegetation Models (DVMs) with simple large-area parameterisations of woody biomass (typically used in current ESMs) and complex second generation DVMs, that explicitly simulate demographic processes and landscape heterogeneity of forests. The key simplification in the POP approach, compared with second-generation DVMs, is to compute physiological processes such as assimilation at grid-scale (with CABLE or a similar land surface model), but to partition the grid-scale biomass increment among age classes defined at sub grid-scale, each subject to its own dynamics. POP was successfully demonstrated along a savanna transect in northern Australia, replicating the effects of strong rainfall and fire disturbance gradients on observed stand productivity and structure. Here, we extend the application of POP to a range of forest types around the globe, employing paired observations of stem biomass and density from forest inventory data to calibrate model parameters governing stand demography and biomass evolution. The calibrated POP model is then coupled to the CABLE land surface model and the combined model (CABLE-POP) is evaluated against leaf-stem allometry observations from forest stands ranging in age from 3 to 200 yr. Results indicate that simulated biomass pools conform well with observed allometry. We conclude that POP represents a preferable alternative to large-area parameterisations of woody biomass turnover, typically used in current ESMs.

  14. 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; 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.

  15. 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.; Mao, J.; Shi, X.; Truesdale, J.; Craig, A.; Calvin, K.; Jones, A.; Collins, W. D.; Edmonds, J.; Hurtt, G. C.; Thornton, P.; Thomson, A.

    2014-11-01

    Climate projections depend on scenarios of fossil fuel emissions and land use change, and the Intergovernmental Panel on Climate Change (IPCC) AR5 parallel process assumes consistent climate scenarios across integrated assessment and earth system models (IAMs and ESMs). The CMIP5 (Coupled Model Intercomparison Project Phase 5) 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 IAMs. 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. For RCP4.5, CESM global afforestation is only 22% of GCAM's 2005 to 2100 afforestation. Likewise, only 17% of GCAM's 2040 afforestation, and zero pasture loss, were transmitted to CESM within the directly coupled model. This is a problem because GCAM relied on afforestation to achieve RCP4.5 climate stabilization. GLM modifications and sharing forest area between GCAM and GLM within the directly coupled model did not increase CESM afforestation. Modifying the land use translator in addition to GLM, however, enabled CESM to include 66% of GCAM's afforestation in 2040, and 94% of GCAM's pasture loss as grassland and shrubland losses. This additional afforestation increases CESM vegetation carbon gain by 19 PgC and decreases atmospheric CO2 gain by 8 ppmv from 2005 to 2040, which demonstrates that CESM without additional afforestation simulates a different RCP4.5 scenario than prescribed by GCAM. Similar land cover inconsistencies exist in other CMIP5 model results, primarily because land cover information is not shared between models. Further work to harmonize land cover among models will be required to increase fidelity between IAM scenarios and ESM simulations and realize the full potential of scenario-based earth system simulations.

  16. Integrated corner reflector InSAR, SI and GPS characterization of complex earth slide deformations, Little Smoky River, Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Froese, C. R.; Poncos, V.; Murhagan, K.; Hawkins, R.; Skirrow, R.; Singhroy, V.

    2009-04-01

    Since the construction of the highway across the Little Smoky River in 1957, slope movements on both valley walls have lead to significant ongoing maintenance for both the highway and the bridge crossing. As the river has changed courses over it's period of incision, numerous landslides of different ages and orientations impact on the road infrastructure. In addition, downcutting into the thick infill of glacial sediments has lead to large, compound earth slides moving in both translational and rotational components. Previous studies associated with road maintenance and repair has relied on conventional point source geotechnical instrumentation, slope inclinometers, at discrete locations. As the landslides impacting on the road are on the scale of many kilometers in width and length the point source readings adjacent to the highway have not allowed for proper characterization of deformation rates on other portions of the valley walls. As options are currently being considered for re-alignment of the highway, data on the relative state of stability of other portions of the valley walls are critical. In order to provide a better global view of the state of stability of the valley walls of the Little Smoky River a series of 18 corner reflectors were installed at strategic locations along the valley walls. This included locations where reflectors were co-located with conventional geotechnical instrumentation and areas where no monitoring had been previously attempted. Each reflector was aimed for optimal orientation for readings with Radarsat F2N ascending beam mode on a 24 day return cycle. During the initial installation period in October 2006, GPS readings were taken on all reflectors with second epoch of readings conducted in August 2008. As well, during this time period bi-annual slope inclinometer readings were collected to provide indications of the horizontal component of the displacements. These two set of ground data were compared, along with observations of slope morphology in order to interpret the InSAR line-of-sight observations and provide a more complete picture of deformations on the valley walls.

  17. 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 vegetation distribution by still keeping major processes of vegetation dynamics like mortality and competition among plant functional types. We prescribed observed burnt areas from the GFED dataset as well as from the Alaskan and Canadian national fire databases in LPJmL to better reproduce observed fire dynamics. We evaluated LPJmL with optimized parameters against independent data streams. LPJmL with a new phenology scheme and optimized parameters better represents spatial patterns of gross primary production, biomass, soil organic carbon, evapotranspiration and tree cover than the original model. LPJmL-DIS is able to reproduce spatial patterns and observed temporal dynamics of FAPAR from seasonal to decadal scales in all major biomes. We performed several model experiments to disentangle the spatial and temporal importance of temperature, radiation, water availability, CO2 fertilization, fire activity and permafrost changes on the seasonal to decadal variability of vegetation greenness. Our results indicate that water availability is a major driver for the seasonal to decadal variability of vegetation greenness in tropical, temperate and boreal biomes. The developed LPJmL data integration system enables to reanalyse recent trends in vegetation greenness and their environmental drivers by combining earth observation data of multiple environmental variables in a consistent process-based global vegetation model framework.

  18. Earth\\'s Surface

    NSDL National Science Digital Library

    Ms. Mathis

    2008-01-11

    You have already learned about the four major parts of Earth\\'s system: atmosphere, hydrosphere, biosphere, and geosphere. Go to the following sites to learn more about rocks and minerals, continental drift, and geologic time. When you finish viewing all the sites, you will participate in a problem-based learning activity, \\"The Case of the Disappearing Dirt.\\" Topographic Maps All About Geology Answer the questions on the handout. Erosion and Weathering Summarize what your learned about erosion and weathering. Examine a landscape formed by erosion Observe the effects of mechanical weathering Plate Tectonics FAQ s About Rocks and Fossils Igneous Rocks Rocks and Minerals Slide Show Rock Cycle Observe an animation of metamorphic rocks forming Continental Drift Mineralogy 4 kids : rockin Internet site : the best place to learn about rocks and minerals Draw a picture of the rock cycle. Coasting Away ...

  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 content through OAI-MPH has been successfully tested with several organizations. The protocol appears to be a prime candidate for sharing metadata throughout the international community. Data services for visualizing and analyzing data have become valuable assets in facilitating the use of data. Data providers are offering many of their data-related services through the directory. The IDN plans to develop a service-based architecture to further promote the use of web services. During the IDN Task Team session, ideas for further enhancements will be discussed.

  1. Integration

    NSDL National Science Digital Library

    2013-06-21

    In this video, we become familiar with integrals, both by understanding them as sums of areas under plots of functions, and by understanding them as anti-derivatives. We present the u-substitution rule, which is the analog of the chain rule for differentiating composite functions.

  2. Earth Fun!

    NSDL National Science Digital Library

    miss.whit

    2009-10-09

    Futher Discovering Volcanos and how they work. Lets go on a Virtual field trip to a volcano, plus look at interactive games and lessons on volcanos and the Earth. This is our virtual field trip! Hop aboard, and hold on tight while we discover one of Earths great wonders. Volcano Field Trip Click here to learn more about volcanos and how they work! Earth: Plates on the Move Make Your Own Earth Science Stationery Making Rocks Meet the Earth OLogists Volcano! What Do You Know About Earth Science? ...

  3. 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: shyao@nju.edu.cn, E-mail: ybchen@nju.edu.cn; Zhang, Shan-Tao; Gu, Zheng-Bin; Zhou, Jian; Lu, Ming-Hui; Chen, Yan-Feng [National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering, Nanjing University, Nanjing 210093 (China); Chen, Y. B., E-mail: shyao@nju.edu.cn, E-mail: ybchen@nju.edu.cn [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China); Shi, Y. G. [Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    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.

  4. Critical Zone Observatories (CZOs): Integrating measurements and models of Earth surface processes to improve prediction of landscape structure, function and evolution

    NASA Astrophysics Data System (ADS)

    Chorover, J.; Anderson, S. P.; Bales, R. C.; Duffy, C.; Scatena, F. N.; Sparks, D. L.; White, T.

    2012-12-01

    The "Critical Zone" - that portion of Earth's land surface that extends from the outer periphery of the vegetation canopy to the lower limit of circulating groundwater - has evolved in response to climatic and tectonic forcing throughout Earth's history, but human activities have recently emerged as a major agent of change as well. With funding from NSF, a network of currently six CZOs is being developed in the U.S. to provide infrastructure, data and models that facilitate understanding the evolution, structure, and function of this zone at watershed to grain scales. Each CZO is motivated by a unique set of hypotheses proposed by a specific investigator team, but coordination of cross-site activities is also leading to integration of a common set of multi-disciplinary tools and approaches for cross-site syntheses. The resulting harmonized four-dimensional datasets are intended to facilitate community-wide exploration of process couplings among hydrology, ecology, soil science, geochemistry and geomorphology across the larger (network-scale) parameter space. Such an approach enables testing of the generalizability of findings at a given site, and also of emergent hypotheses conceived independently of an original CZO investigator team. This two-pronged method for developing a network of individual CZOs across a range of watershed systems is now yielding novel observations and models that resolve mechanisms for Critical Zone change occurring on geological to hydrologic time-scales. For example, recent advances include improved understanding of (i) how mass and energy flux as modulated by ecosystem exchange transforms bedrock to structured, soil-mantled and/or erosive landscapes; (ii) how long-term evolution of landscape structure affects event-based hydrologic and biogeochemical response at pore to catchment scales; (iii) how complementary isotopic measurements can be used to resolve pathways and time scales of water and solute transport from canopy to stream, and (iv) how feedbacks between the Critical Zone, changing climate and changing land use are occurring on timescales relevant to human decisions and policy making.

  5. 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 ?em of ~1.1 × 10-21 cm2 for ~ 5.0 × 1021 cm-3 Tb3+. This results in an optical gain parameter ?em*? of ~2.5 × 10-24 cm2s, what could be of interest for implementation of a Tb3+ fiber laser.

  6. 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 ?em of ~1.1 × 10?21?cm2 for ~ 5.0 × 1021?cm?3 Tb3+. This results in an optical gain parameter ?em*? of ~2.5 × 10?24?cm2s, what could be of interest for implementation of a Tb3+ fiber laser. PMID:25754819

  7. Earth's Seasons

    NSDL National Science Digital Library

    Rochester Museum and Science Center, Strasenburgh Planetarium

    A computer animation on the reason for the seasons. Voice-over describes the motion of Earth around the sun to show how the sun's light impacts the tilted Earth at different times of the year, causing seasonal changes.

  8. Google Earth

    NSDL National Science Digital Library

    2009-01-01

    Google Earth has gone underwater with this latest iteration of their popular Earth-roaming application. Along with traveling the usual roads provided by previous versions of Google Earth, visitors can now visit the bottom of the Mariana Trench, learn about ocean observations, and even discover new places to surf and dive. On the Google Earth homepage, visitors can take a guided tour of all these new features. This version is compatible with all operating systems.

  9. Effect of transition metal doping and carbon doping on thermoelectric properties of YB{sub 66} single crystals

    SciTech Connect

    Mori, Takao [National Institute for Materials Science, Namiki 1-1, Tsukuba 305-0044 (Japan)]. E-mail: MORI.Takao@nims.go.jp; Tanaka, Takaho [National Institute for Materials Science, Namiki 1-1, Tsukuba 305-0044 (Japan)

    2006-09-15

    We have been investigating the high-temperature thermoelectric properties of some novel rare earth borides with a structure containing B{sub 12} icosahedra. Doping effects on the TE properties in such systems were investigated for the first time. A series of Nb-doped YB{sub 66} and C-doped YB{sub 66} single crystals were grown by the floating zone method. The Nb-doped compounds have approximate chemical formulas ranging from YNb{sub 0.30}B{sub 66} to YNb{sub 0.33}B{sub 66} while the C-doped compound has a formula of YB{sub 66}C{sub 0.6}. The effect of Nb-doping on the thermoelectric properties was not monotonic and appears to be complex. As a result of Nb-doping, the room temperature resistivity and the characteristic temperature T{sub 0} were considerably reduced. At room temperature the power factor of the Nb-doped YB{sub 66} sample with 89% site occupancy was three times greater than that of non-doped YB{sub 66}. However, in the important high-temperature region, the non-doped sample actually exhibited the highest power factor for T>550K. Furthermore, owing to a structural feature of YB{sub 66}, thermal conductivity actually increases with doping of transition metals. Taking into account all the thermoelectric properties, transition metal doping of YB{sub 66} is therefore not suitable for our purposes. On the other hand, doping of carbon, which is assumed not to go into the same sites as the transition metals, yielded a lowering of the thermal conductivity. Furthermore, contrary to Nb-doping, carbon doping did not result in a reversal of the relative magnitude of resistivity at extremely high temperatures and therefore, an increase in the figure of merit of factor 2 was realized at 1000K.

  10. Earth Calendar

    NSDL National Science Digital Library

    Jeffrey Barker

    This handout lists major events in Earth history with approximate ages (in millions of years before present). The calendar date is determined by setting midnight, January 1, to correspond with the formation of the Earth, and setting the following midnight, December 31, to correspond to the present. Thus, the entire history of the Earth is displayed as a single calendar year.

  11. Edible Earth

    NSDL National Science Digital Library

    American Museum of Natural History

    2011-08-20

    In this activity, learners make a model of the solid Earth's layers that's good enough to eat! Learners use tasty foodstuffs to simulate Earth's inner core, outer core, mantle, and crust. The recipe includes ingredients for one edible Earth, but can be doubled or tripled to accommodate groups of learners. This activity requires adult supervision.

  12. Earth's Layers

    NSDL National Science Digital Library

    Mrs. Walls

    2011-01-30

    Complete a poster all about Earth's Layers! Directions: Make a poster about Earth's Layers. (20 points) Include at least (1) large picture (15 points) on your poster complete with labels of every part (10 points). (15 points) Include at least three (3) facts about Earth's Layers. (5 points each) (15 points) Write at least a three sentence summary of your poster ...

  13. Snowball Earth

    NSDL National Science Digital Library

    Audio program from the University of Wisconsin's Earthwatch Radio discusses the notion of the entire planet covered with ice. Doug Macdougall is an earth scientist at the University of California-San Diego and author of a new book called "Frozen Earth." He says the planet-wide freeze is known as "Snowball Earth."

  14. Earth Changes

    NSDL National Science Digital Library

    1998-01-01

    These activities give students a hands-on feeling for the relationships between the Earth's structural layers and aid them in understanding the world around them. They will be able to identify (by modeling) the Earth's structure (core, mantle and crust) and also (by experiment and demonstration) the forces within the Earth that cause constant changes on the surface (earthquakes).

  15. Planet Earth

    NSDL National Science Digital Library

    For those interested in a global view of the weather, Planet Earth is a "real-time 3-D model of the Earth with continuously updating night shadows and clouds." Cloud images are provided by the University of Wisconsin-Madison Space Science and Engineering Center. Planet Earth is shareware with a fee of $29.95.

  16. Integration of ASTER thermal infrared data and the Google Earth application to examine the relationship between sand transport pathways and dust emission hot-spots

    NASA Astrophysics Data System (ADS)

    Scheidt, S. P.; Lancaster, N.; Ramsey, M.

    2007-12-01

    The identification and characterization of major mineral dust source areas from the Sahara Desert and the composition of these particulates are critical to our understanding of global dust production, models of atmospheric emission and transport, and determination of radiative properties of dust plumes from desert regions. The locations of many of these dust hot-spots have been determined using data such as the Total Ozone Mapping Spectrometer aerosol index (TOMS AI), showing that the largest sources of global dust are located in the Sahara Desert of west and central Africa. Studies using geochemical tracers, surface observations, analysis of meteorological data, and remote sensing have, however, arrived at different and sometimes conflicting delineations of Saharan dust sources. Geomorphic environment is a major control on dust emission source and process. Surface and remote sensing observations of the Bodele Depression, the largest dust source in the Sahara, show that sand saltation on the playa surface and the abrasion of material are the primary processes in generating dust. In order to test the hypothesis that other major natural global dust emission sources are linked to the interaction of sand transport along defined pathways and dust sources, multispectral thermal infrared (TIR) data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) are integrated with the high resolution, mosaicked image data available from the Google Earth application. The geomorphic environment, surface composition and their relative importance as a control on dust emissions are assessed using high resolution data at dust hot-spots that were identified by the TOMS AI at the much lower spatial resolution of one pixel/degree.

  17. Broadband near infrared emission in antimony-germanate glass co-doped with erbium and thulium ions

    NASA Astrophysics Data System (ADS)

    Dorosz, Dominik; Zmojda, Jacek; Kochanowicz, Marcin

    2014-07-01

    Antimony-germanate glasses co-doped with Er/Tm ions as a material for active waveguides application have been investigated. In result of optimizations of rare earths, concentration wide (??FWHM=420 nm) luminescence emission in the range of 1.4 to 1.9 ?m was obtained for molar composition of 1%Er2O3: 0.25%TmO. The influence of the molar ratio of active ions on the luminescence spectra has been investigated. Luminescent properties of fabricated glass indicate that elaborated glass is promising material for broad tunable integrated laser sources and broadband optical amplifiers.

  18. Synthesis and evaluation of ultra-pure rare-earth-coped glass for laser refrigeration

    SciTech Connect

    Patterson, Wendy M [Los Alamos National Laboratory; Hehlen, Markus P [Los Alamos National Laboratory; Epstein, Richard I [Los Alamos National Laboratory; Sheik-bahae, Mansoor [UNM

    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.

  19. Theoretical analysis of fiber lasers emitting around 810 nm based on thulium-doped silica fibers with enhanced 3

    E-print Network

    Boyer, Edmond

    Theoretical analysis of fiber lasers emitting around 810 nm based on thulium-doped silica fibers-earth doped fiber lasers are situated around 1, 1.5 and 2 µm. In this paper we investigate thulium-doped fiber-power fiber lasers. The single-transverse mode, high-power laser source in the 800 nm spectral band can

  20. Cathodoluminescence Study of GadoliniumDoped Yttrium Oxide Thin Films Deposited By RadioFrequency Magnetron Sputtering

    E-print Network

    Fitz-Gerald, James M.

    Cathodoluminescence Study of Gadolinium­Doped Yttrium Oxide Thin Films Deposited By Radio A multi­layer gadolinium­doped yttrium oxide thin film was deposited in a combinatorial fashion on a Si-particle detection units. Previous work on rare­earth doped yttrium oxide materials have shown emission from the blue

  1. RADECS 2010 Proceedings Paper LN2 1 Abstract--Radiation effects in ytterbium-doped silica optical

    E-print Network

    Boyer, Edmond

    Stimulated Luminescence, Ytterbium-doped silica optical fibers. I. INTRODUCTION HE radiation-induced degradation of rare-earth-doped fiber amplifiers or lasers has become a crucial concern for the space industry. Radiation effects on erbium (Er)- doped fibers (EDF) has been quite widely investigated for about 10 years

  2. 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 investigators)

    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.

  3. Theoretical study of native and rare-earth defect complexes in -PbF2 Huitian Jiang, Aurora Costales,* Miguel A. Blanco,

    E-print Network

    Pandey, Ravi

    ARTICLES Theoretical study of native and rare-earth defect complexes in -PbF2 Huitian Jiang, Aurora manuscript received 31 January 2000 Native and rare-earth-doped point-defects in -PbF2 are studied data. In the rare-earth doped PbF2, a site preference of the charge-compensating fluorine interstitial

  4. Earth Day Main > Sierra Club

    NSDL National Science Digital Library

    This page from the Sierra Club has links and information dedicated to the celebration of Earth Day. Resources on the site contain information on projects across the country. There are also ideas for integrating eco-friendly projects into your community, and energy saving tips for the home, office and city as a whole. Fact sheets on global warming and other educational materials are also available for integration into your own Earth Day celebration.

  5. 20 W single-mode Yb3+ -doped phosphate fiber laser

    E-print Network

    Byer, Robert L.

    codes: 060.2290, 140.3510, 140.3570. In the past few years, cw rare-earth-doped silica fi- bers have for com- pact geometries. The second approach, shortening the fiber, requires increasing the rare-earth-ion con- centration. Because of the low solubility of rare-earth oxides in silica, this concentration can

  6. "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…

  7. 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.

  8. Dynamic Earth

    NSDL National Science Digital Library

    Ashlinn Quinn

    2007-01-01

    Dynamic Earth consists of four sections and an assessment. Each section explores one aspect of the earth's structure and the movement of its tectonic plates. Simply follow the instructions on the screen to learn about the layers that make up the earth; how the continents arrived at their current locations; the constant movement of the tectonic plates; and the volcanoes, earthquakes, and other events that result from the movements of the plates. Students will view animations, read explanations, and use their mouse to drag and drop the earth's continents in their correct places, highlight features on a map, and cause earth's tectonic plates to move. At various points, students will check their knowledge by taking a quick quiz or playing a game to see how much they have learned about the Dynamic Earth. Students should read section introductions carefully, as they give a basic overview of concepts, and use the Glossary to look up definitions to unfamiliar terms.

  9. Wave-vector dependence of rare-earth relaxation in yttrium iron garnet

    Microsoft Academic Search

    D. G. Scotter

    1972-01-01

    A wave-vector dependence of the parallel-pump spin-wave linewidth in rare earth doped YIG is reported. The spin-wave linewidth (?Hk) has the form ?Hk = a + a?c + (b + b?c)k. The a's and b's are constants with the primed values dependent on the particular rare earth and c is the rare-earth doping level. Values of b? are 1.8±0.2, 3.55±0.3,

  10. Earth Floor

    NSDL National Science Digital Library

    This Classroom of the Future (COTF) website highlights information about the Earth and its development through time. Spheres discusses layers of the Earth's environment such as the hydrosphere, Cycles discusses rock and water cycles, and Diversity illustrates different species and genetic variations that have emerged on Earth. Also covered are biomes, adaptation, geologic time, and plate tectonics. Each of these sections is an in-depth tutorial on these specific topics.

  11. Celebrate Earth

    NSDL National Science Digital Library

    Mrs. Rokes

    2009-04-23

    The Earth is truly something to celebrate! Click on the links below and have some fun! Click on the link to send you to a fun website created just for kids like you! Now go celebrate the earth! Kids for Saving Earth Enjoy these other activities as well! Go recycling! A is for Air Discover what all of the letters of the alphabet can stand for! video Get on ...

  12. Earth's Interior

    NSDL National Science Digital Library

    John Louie

    This website contains class notes from a Geology 101 (physical geology) course. It discusses the composition and structure of the Earth's interior. Each layer, the inner core, outer core, mantle, and crust, is covered. Details about each layer explain their composition, temperature, depth, and state. Also covered is how scientists discovered what the interior of the Earth is made of through the use of seismic waves, plate tectonics, and the Earth's magnetic field.

  13. Earth Island

    NSDL National Science Digital Library

    The Earth Island Web site is maintained by the Earth Island Institute (EII). EII also publishes the Earth Island Journal quarterly. The current issue of the journal can be browsed by section or by subject, and offers current news, world reports, and feature articles on a wide range of environmental subject areas. Earth Island also undertakes a number of projects that are discussed at the site as well as in a portion of the journal. The entire site is searchable. This is an excellent site for those interested in keeping up on environmental issues.

  14. Earth Force

    NSDL National Science Digital Library

    "Earth Force engages young people as active citizens who improve the environment and their communities now and in the future." Educators can learn about Earth Force's three programs: Community Action and Problem solving (CAPS), the Global Rivers Environmental Education Network (GREEN), and Earth Force After School. Users can discover students' many accomplishments such as creating reusable fabric grocery bags, recycling cell phones and ink cartridges to earn money, and cleaning up litter. The Tools for Teachers section offers evaluation results, a quality rubric, and a description of the six-step Earth Force community action and problem-solving process.

  15. Linking the Global Geodetic Observing System (GGOS) to the Integrated Global Observing Strategy Partnership (IGOS-P) through the Theme ‘Earth System Dynamics’

    Microsoft Academic Search

    H.-P. Plag; G. Beutler; R. Forsberg; C. Ma; R. Neilan; M. Pearlman; B. Richter; S. Zerbini

    When setting up GGOS as a project, the IAG Executive Committee asked the GGOS Steering Committee to establish a relationship\\u000a with IGOS-P. IGOS-P addresses a number of problems and components of Earth observing systems in the frame of specific Themes.\\u000a The IGOS-P Theme process will also be an important mechanism for the development of the components of the Global Earth

  16. 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.; Mao, J.; Shi, X.; Truesdale, J.; Craig, A.; Calvin, K.; Jones, A.; Collins, W. D.; Edmonds, J.; Hurtt, G. C.; Thornton, P.; Thomson, A.

    2014-05-01

    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 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 models. High RCP4.5 afforestation might also contribute to inconsistencies as some ESMs might impose bioclimatic limits to potential forest area and have different rates of forest growth than projected by RCP4.5. Further work to harmonize land cover among models will be required to address this problem.

  17. 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 Kit.

  18. Earth Day

    NSDL National Science Digital Library

    On April 22, 2005, people around the world will celebrate the 35th anniversary of Earth Day. This Topic in Depth focuses on the past and present of this significant day. From the Wisconsin Historical Society, the first two sites contain historical documents pertaining to Earth Day. The first (1) document features a May 1970 issue of The Gaylord Nelson Newsletter reporting on the first Earth Day. The second (2) document is a speech by Nelson entitled "An Environmental Agenda for the 70's." Housed in the archives of the US Environmental Protection Agency (EPA) website, the next two sites also contain historical documents. The first (3) site contains an article written by Nelson for the EPA Journal in April of 1980, entitled "Earth Day '70: What It Meant." The second (4) site contains an article written by John C. Whitaker (former Interior undersecretary in the Nixon administration) for the EPA Journal in the summer of 1998. The article is entitled "Earth Day Recollections: What It Was Like When the Movement Took Off." The (5) Earth Day Network (first mentioned in the April 4, 2003, Scout Report for Life Sciences) works "to broaden the environmental movement worldwide and to educate and mobilize people, governments, and corporations to take responsibility for a clean and healthy environment." In addition to information sections about Ongoing Programs, Current Campaigns, and News, the Earth Day Network website contains Earth Day 2005 Materials for organizers. From EarthDay.gov, Take Action In Your Classroom (6) offers links to a variety of environmental education resources. The next website, from the U.S. Army Environmental Center, presents (7) Army Earth Day; and links to information about the Army's environmental activities. The final (8) site is an Earth Day-inspired educational website (first reported on in the April 14, 1999 Scout Report for Science & Engineering) from the Wilderness Society. The site offers a collection of environmental education resources for teachers and students. [NL

  19. 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

    2015-01-01

    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 ?em of ~1.1 × 10(-21)?cm(2) for ~ 5.0 × 10(21)?cm(-3) Tb(3+). This results in an optical gain parameter ?em*? of ~2.5 × 10(-24)?cm(2)s, what could be of interest for implementation of a Tb(3+) fiber laser. PMID:25754819

  20. Song of the Earth

    NSDL National Science Digital Library

    This PBS Web site is the online companion to the Nature documentary "Song of the Earth," hosted by David Attenborough. The program explores the elemental purpose of music and offers a fascinating look at the connection between animal sounds and human music. The site includes two detailed lesson plans that integrate science and language arts, designed for grades 9-12. Learning objectives include conducting research on animal behavior, applying scientific methodology, synthesizing information to create presentations, and more. The main Song of the Earth Web site has other features -- such as a list of related links and a photo essay of animal music -- that would make excellent additions to classroom activities.

  1. Rainbow Earth.

    ERIC Educational Resources Information Center

    Arizona State Dept. of Library and Archives, Phoenix.

    The environment is a great concern in the 1990s, and everyone needs to work at maintaining our planet. The 1992 Arizona State Library Reading Program, "Rainbow Earth," provides children with many techniques they can use to help the Earth. This reading program guide provides information on the following: goals, objectives, and evaluation; getting…

  2. Earth Impact

    NSDL National Science Digital Library

    Integrated Teaching and Learning Program,

    This activity poses the question: What would happen if a meteor or comet impacted Earth? Students simulate an impact in a container of sand using various-sized rocks, all while measuring, recording and graphing results and conclusions. Then students brainstorm ways to prevent an object from hitting the Earth.

  3. Selective Solid-Phase Epitaxy of Ultra-Shallow p+ Aluminum-Doped Silicon Junctions

    E-print Network

    Technische Universiteit Delft

    ). The grown material is highly p+ -doped with aluminum. The abruptness of the doping transition has beenSelective Solid-Phase Epitaxy of Ultra-Shallow p+ Aluminum-Doped Silicon Junctions for Integration and Materials, DIMES, Delft University of Technology, Feldmannweg 17, 2628 CT Delft, The Netherlands. 2 Kavli

  4. Techniques for integrating the animations, multimedia, and interactive features of NASA’s climate change website, Climate Change: NASA’s Eyes on the Earth, into the classroom to advance climate literacy and encourage interest in STEM disciplines

    NASA Astrophysics Data System (ADS)

    Tenenbaum, L. F.; Jackson, R.; Greene, M.

    2009-12-01

    I developed a variety of educational content for the "Climate Change: NASA’s Eyes on the Earth" website, notably an interactive feature for the "Key Indicators: Ice Mass Loss" link that includes photo pair images of glaciers around the world, changes in Arctic sea ice extent videos, Greenland glacial calving time lapse videos, and Antarctic ice shelf break up animations, plus news pieces and a Sea Level Quiz. I integrated these resources and other recent NASA and JPL climate and oceanography data and information into climate change components of Oceanography Lab exercises, Oceanography lectures and Introduction to Environmental Technology courses. I observed that using these Internet interactive features in the classroom greatly improved student participation, topic comprehension, scientific curiosity and interest in Earth and climate science across diverse student populations. Arctic Sea Ice Extent Summer 2007 Credit: NASA

  5. 146 Earth Science 147 Earth Science

    E-print Network

    Richards-Kortum, Rebecca

    146 Earth Science 147 Earth Science ESCI 101 The Earth or ESCI 102 Evolution of the Earth or ESCI 107 Oceans and Global Change or ESCI 108 Crises of the Earth ESCI 105 Introductory Lab for Earth Geophysics I ESCI 444 Exploration Geophysics II or ESCI 446 Solid Earth Geophysics Math and Other Sciences

  6. Influence of high magnetic field on the luminescence of Eu3+-doped glass ceramics

    NASA Astrophysics Data System (ADS)

    Jiang, Wei; Zhang, Junpei; Chen, Weibo; Chen, Ping; Han, Junbo; Xu, Beibei; Zheng, Shuhong; Guo, Qiangbing; Liu, Xiaofeng; Qiu, Jianrong

    2014-09-01

    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 Eu3+-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 Eu3+ 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 Eu3+ 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.

  7. 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: xfliu@zju.edu.cn, E-mail: qjr@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Zhang, Junpei; Han, Junbo [Wuhan National High Magnetic field Center, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Qiu, Jianrong, E-mail: xfliu@zju.edu.cn, E-mail: qjr@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027 (China); State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, Guangdong 510640 (China)

    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.

  8. Multifunctionality of rare earth doped nano ZnSb2O6, CdSb2O6 and BaSb2O6: photocatalytic properties and white light emission.

    PubMed

    Dutta, Dimple P; Ballal, Anand; Singh, Anamika; Fulekar, M H; Tyagi, A K

    2013-12-28

    Undoped MSb2O6 (where M = Zn, Cd, Ba) and single and double doped MSb2O6:RE (where RE = Tb(3+) and Eu(3+)) nanophosphors were synthesized through a simple sonochemical process and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), diffuse reflectance (DRS) and photoluminescence (PL) spectrophotometry. The TEM micrographs show that the resulting nanoparticles have mostly a spherical shape. Energy transfer was observed from the host to the dopant ions and characteristic green emissions from Tb(3+) ions and red emissions from Eu(3+) ions were observed. The chromaticity diagrams of the ZnSb2O6:Tb(3+)(1.2%):Eu(3+)(0.8%), CdSb2O6:Eu(3+)(0.5%):Tb(3+)(1.5%) and BaSb2O6:Eu(3+)(1%):Tb(3+)(1%) nanophosphors yielded CIE and CCT (correlated color temperature) values in the white light region. The photocatalytic activities of the undoped and double doped antimonates were evaluated for the degradation of rhodamine B (RhB) under UV light. Undoped MSb2O6 (where M = Zn, Cd, Ba) as well as ZnSb2O6:Tb(3+)(1.2%):Eu(3+)(0.8%), CdSb2O6:Eu(3+)(0.5%):Tb(3+)(1.5%) and BaSb2O6:Eu(3+)(1%):Tb(3+)(1%) samples exhibited good photodegradation capacity for RhB. Thus double doped ZnSb2O6:Tb(3+)(1.2%):Eu(3+)(0.8%), CdSb2O6:Eu(3+)(0.5%):Tb(3+)(1.5%) and BaSb2O6:Eu(3+)(1%):Tb(3+)(1%) can be termed a bifunctional material exhibiting both photocatalytic properties and white light emission. PMID:24091883

  9. Vegetation signature in the observed globally-integrated spectrum of Earth: Modeling the red edge strength using simultaneous cloud data and application for extrasolar planets

    E-print Network

    Pilar Montanes-Rodriguez; E. Palle; P. R. Goode

    2006-04-20

    The vegetation's ``red edge'', an intensity bump in the Earth's spectrum near 700 $nm$ when sunlight is reflected from greenery, is often suggested as a tool in the search for life in terrestrial-like extrasolar planets. Here, through ground-based observations of the Earth's spectrum, satellite observations of clouds, and an advanced atmospheric radiative transfer code, we determine the temporal evolution of the vegetation signature of Earth. The excellent agreement between models and observations motivated us to probe more deeply into the red edge detectability using real cloud observations at longer time scales. Overall, we find the evolution of the red edge signal in the globally-averaged spectra to be weak, and only attributable to vegetation changes when the real land and cloud distributions for the day are known. However, it becomes prominent under certain Sun-Earth-Moon orbital geometries, which are applicable to the search for life in extrasolar planets. Our results indicate that vegetation detection in Earth-like planets will require a considerable level of instrumental precision and will be a difficult task, but not as difficult as the normally weak earthshine signal might seem to suggest.

  10. 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…

  11. The Earth

    NSDL National Science Digital Library

    This lesson covers the interior of the Earth, geological differentiation, plate tectonics, composition and layers of the atmosphere, weather and climate, consequences of rotation for weather, the magnetic field, magnetosphere and Van Allen Radiation Belts of Earth, auroras (Northern and Southern Lights, and imaging the Earth. There is information on seismic waves, and convection currents; an animation of continental drift; evidence for plate tectonics, including maps of crustal plate boundaries and the age of the sea floor crustal plates; and explanations of solar heating, Coriolis forces, cyclones and anticyclones.

  12. Visible Earth

    NSDL National Science Digital Library

    NASA's Visible Earth is a searchable directory of images, visualizations, and animations of Earth science-related images being produced by several NASA projects including Terra and SeaWiFS. Images are categorized by location, satellite, and topic, and are also searchable using a full-text search engine. Resources include agriculture, atmosphere, biosphere, cryosphere, human dimensions, hydrosphere, land surface, oceans, radiance or imagery, and solid earth. Accompanying each image are credits, data about the image, the satellite it was taken from, a description of what is shown, and a high-resolution viewable image.

  13. Cerium filling and doping of cobalt triantimonide

    Microsoft Academic Search

    Donald T. Morelli; Gregory P. Meisner; Baoxing Chen; Siqing Hu; Ctirad Uher

    1997-01-01

    We have fabricated and studied the structural, magnetic, and transport properties of filled skutterudites of the form CeyFe4-xCoxSb12 with 0< y<1 and x=3.25 and 4. For samples containing 100% Co, Ce can be inserted into approximately 10% of the voids in the skutterudite structure. It is shown that the rare earth is trivalent and dopes the host CoSb3 n-type. With

  14. Nanoparticle doping process for improved fibre amplifiers and lasers

    NASA Astrophysics Data System (ADS)

    Pastouret, A.; Gonnet, C.; Collet, C.; Cavani, O.; Burov, E.; Chaneac, C.; Carton, A.; Jolivet, J. P.

    2009-02-01

    Manufacture fiber amplifiers and lasers in a versatile and cost effective way while controlling rare-earths chemical environment becomes a real technology differentiator. A MCVD compatible Nanoparticle Doping Process has been developed to master with a higher accuracy rare earth amplifier and ytterbium laser fibers. Improved doped erbium fibers with C-band gain shape were obtained with much less aluminum content and unprecedented low background attenuation losses. This process should better show its merits in high power regime paving the way to fiber amplifiers and lasers for low cost new performances.

  15. 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.

  16. 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.

  17. Earth Day

    NSDL National Science Digital Library

    The State University of New York at Buffalo presents this History of Earth Day website. The goal of the site is that teachers and students can better understand the development and purpose of Earth Day. In addition to the history, SUNY-Buffalo has compiled a series of websites complete with projects associated with Earth Day, appropriate for children, high school students, and college undergrads. Furthermore, the legal aspect of Earth Day - environmental legislation, EPA standards, and Global Climate Change legislation - are also discussed on the site. A list of further sites is also provided if users want more information on this national effort to help solve environmental issues such as pollution, overpopulation, and global warming. Teachers will find this website both informative and helpful in developing appropriate teaching curricula connected to this holiday, while students can have fun learning and creating projects of their own that contribute to preserving the environment.

  18. Earth Systems

    NSDL National Science Digital Library

    Houghton Mifflin Science

    This self-contained module on Earth systems includes a range of fun activities that students can perform in the classroom and at home with family members. They impart important concepts such as observation, identification, measurement, and differentiation.

  19. Earth's Surface

    NSDL National Science Digital Library

    Houghton Mifflin Science

    This self-contained module on Earth's crust includes a range of fun activities that students can perform in the classroom and at home with family members. They impart important concepts such as observation, identification, measurement, and differentiation.

  20. Erbium-doped and Raman microlasers on a silicon chip fabricated by the solgel process

    E-print Network

    Carmon, Tal

    with erbium implanted silica layers,3 low threshold rare- earth-doped microlasers on-a-chip have beenErbium-doped and Raman microlasers on a silicon chip fabricated by the sol­gel process Lan Yang 2005; published online 25 February 2005 We report high-Q sol­gel microresonators on silicon chips

  1. Earth Viewers

    Microsoft Academic Search

    Mathias Lemmens

    \\u000a One of the most influential developments boosting the application of geo-information technologies in a wide variety of scientific\\u000a and professional disciplines has its origin outside the geomatics field although the establishment of the technology heavily\\u000a relies on recent accomplishments in geo-information technology. The developments referred to concern the emergence of Earth\\u000a viewers such as Google Earth or Bing Maps accessible

  2. Earth’s Earliest Atmospheres

    PubMed Central

    Zahnle, Kevin; Schaefer, Laura; Fegley, Bruce

    2010-01-01

    Earth is the one known example of an inhabited planet and to current knowledge the likeliest site of the one known origin of life. Here we discuss the origin of Earth’s atmosphere and ocean and some of the environmental conditions of the early Earth as they may relate to the origin of life. A key punctuating event in the narrative is the Moon-forming impact, partly because it made Earth for a short time absolutely uninhabitable, and partly because it sets the boundary conditions for Earth’s subsequent evolution. If life began on Earth, as opposed to having migrated here, it would have done so after the Moon-forming impact. What took place before the Moon formed determined the bulk properties of the Earth and probably determined the overall compositions and sizes of its atmospheres and oceans. What took place afterward animated these materials. One interesting consequence of the Moon-forming impact is that the mantle is devolatized, so that the volatiles subsequently fell out in a kind of condensation sequence. This ensures that the volatiles were concentrated toward the surface so that, for example, the oceans were likely salty from the start. We also point out that an atmosphere generated by impact degassing would tend to have a composition reflective of the impacting bodies (rather than the mantle), and these are almost without exception strongly reducing and volatile-rich. A consequence is that, although CO- or methane-rich atmospheres are not necessarily stable as steady states, they are quite likely to have existed as long-lived transients, many times. With CO comes abundant chemical energy in a metastable package, and with methane comes hydrogen cyanide and ammonia as important albeit less abundant gases. PMID:20573713

  3. EARTH OBSERVATIONS

    E-print Network

    unknown authors

    2013-01-01

    Each year, Federal agencies invest billions of dollars in civil Earth observations. Through these investments, the U.S. government ensures that the Nation’s decision makers have the information they need about climate and weather, disaster events, land-use change, ecosystem health, natural resources, and many other characteristics of the planet. Section 702 of the NASA Authorization Act of 2010, signed into law on October 11, 2010, instructs the Director of the Office of Science and Technology Policy (OSTP) to establish a mechanism to ensure greater coordination of civilian Earth observations, including the development of a strategic implementation plan that is updated at least every three years. In December 2010, I reported to Congress on the formation of a National Earth Observations Task Force to respond to this direction. The attached National Strategy for Civil Earth Observations, completed by the Task Force, establishes a three-year assessment and planning framework for Earth observations organized by major areas of societal benefit, initiates a prioritization of national observing systems according to those areas, and codifies guidelines for Federal agencies concerning the effective management of Earth observation data. As this National Strategy document describes, the Administration has begun a broad and

  4. Digital Earth

    NASA Astrophysics Data System (ADS)

    de La Beaujardiere, J.

    2001-05-01

    Digital Earth (DE) seeks to make geospatial information broadly and easily available. Vast amounts of natural and cultural information are gathered about the Earth, but it is often difficult to find needed data, to share knowledge across disciplines, and to combine information from several sources. DE defines a framework for interoperability by selecting relevant open standards from the information technology community. These standards specify the technical means by which publishers can provide or sell their data, and by which client applications can find and access data in an automated fashion. The standardized DE framework enables many types of clients--from web browsers to museum kiosks to research-grade virtual environments--to use a common geospatial information infrastructure. Digital Earth can benefit Earth system education in general, and DLESE in particular, in several ways. First, educators, students and creators of instructional material will benefit from standardized access to georeferenced data. Secondly, educational lesson plans that focus on a region or aspect of the Earth can themselves be considered geospatial information resources that could be cataloged and retrieved through DE. Finally, general public knowledge about our planet will by increased by Digital Earth.

  5. Earth System: Satellites

    NSDL National Science Digital Library

    There are thousands of artificial satellites circling our planet for navigation, communications, entertainment, and science. These satellites are an integral part of our everyday life, and they collect data which cannot be obtained from Earth's surface. This video segment describes the basic components of a satellite and some of applications that have been developed for both geostationary and orbiting satellites. The segment is three minutes fifty seconds in length. A background essay and discussion questions are included.

  6. Building Scientific Workflows for Earth System Modelling with Windows Workflow Foundation

    E-print Network

    Building Scientific Workflows for Earth System Modelling with Windows Workflow Foundation Matthew J developed a framework for the composition, execution and management of integrated Earth system models

  7. 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.

  8. Savage Earth

    NSDL National Science Digital Library

    2002-04-24

    The Savage Earth website is the on-line companion to the PBS television series of the same name. This site tells the stories of several great natural disasters, particularly the eruption of Mt. Vesuvius in 79 A.D. that destroyed Pompeii and the 1994 earthquake in Kobe, Japan. It contains articles on the earth's crust and plate tectonics, earthquakes, volcanoes, and tsunamis. Each article features photographs, animated drawings, and video clips. For example, the earthquakes article includes animations of types of faults and three different kinds of seismic waves. There is also a question and answer section and links to related sites about geology and natural hazards.

  9. Erbium-doped waveguide DBR and DFB laser arrays integrated within an ultra-low-loss Si3N4 platform.

    PubMed

    Belt, Michael; Blumenthal, Daniel J

    2014-05-01

    Record low optical threshold power and high slope efficiency are reported for arrays of distributed Bragg reflector lasers integrated within an ultra-low-loss Si(3)N(4) planar waveguide platform. Additionally, arrays of distributed feedback laser designs are presented that show improvements in pump-to-signal conversion efficiency of over two orders of magnitude beyond that found in previously published devices. Lithographically defined sidewall gratings provide the required lasing feedback for both cavity configurations. Lasing emission is shown over a wide wavelength range (1534 to 1570 nm), with output powers up to 2.1 mW and side mode suppression ratios in excess of 50 dB. PMID:24921766

  10. Coherent properties of single rare-earth spin qubits

    E-print Network

    P. Siyushev; K. Xia; R. Reuter; M. Jamali; N. Zhao; N. Yang; C. Duan; N. Kukharchyk; A. D. Wieck; R. Kolesov; J. Wrachtrup

    2014-05-20

    Rare-earth-doped crystals are excellent hardware for quantum storage of optical information. Additional functionality of these materials is added by their waveguiding properties allowing for on-chip photonic networks. However, detection and coherent properties of rare-earth single-spin qubits have not been demonstrated so far. Here, we present experimental results on high-fidelity optical initialization, effcient coherent manipulation, and optical readout of a single electron spin of Ce$^{3+}$ ion in a YAG crystal. Under dynamic decoupling, spin coherence lifetime reaches $T_2$=2 ms and is almost limited by the measured spin-lattice relaxation time $T_1$=3.8 ms. Strong hyperfine coupling to aluminium nuclear spins suggests that cerium electron spins can be exploited as an interface between photons and long-lived nuclear spin memory. Combined with high brightness of Ce$^{3+}$ emission and a possibility of creating photonic circuits out of the host material, this makes cerium spins an interesting option for integrated quantum photonics.

  11. 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.

  12. 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.

  13. 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.

  14. 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 Georgia and beyond) our model for the NASA-enhancement of an introductory science course as a focal point for teacher preparation and professional development.

  15. Novel Approach to Conformal FINFET Extension Doping

    SciTech Connect

    Zschaetzsch, G.; Vandervorst, W. [imec Kapeldreef 75, B-3001 Leuven (Belgium); Hoffmann, T. Y.; Horiguchi, N. [Instituut voor Kern- en Stralingsfysica, K.U. Leuven, B-3001 Leuven (Belgium); Hautala, J.; Shao, Y. [TEL Epion Inc., 37 Manning Road, Billerica, MA, 01821 (United States)

    2011-01-07

    This paper presents a novel strategy to achieve conformal FINFET extension doping with low tilt-angle beam-line ion implantation. The process relies on the self-aligned cap layer formation exclusively on top of the FIN to tune doping levels in this particular area by partial dopant trapping. The conformality itself is evaluated for n- and p-type dopants by a novel extraction method applied to FIN resistor test structures. Furthermore, the process was integrated into a full NMOS device flow and compared to a highly tilted and more conformal As implant condition.

  16. Earth Movers

    NSDL National Science Digital Library

    This lesson explores plate tectonics and helps students understand how mountains, earthquakes, and volcanoes are related to the movements of plates. Students will learn about the idea of continental drift and the theory of plate tectonics to ascertain a fuller picture of how land formations on the surface of the Earth are shaped by plates moving below the surface.

  17. Impact Earth

    NSDL National Science Digital Library

    Patricia Reiff

    2009-05-01

    This planetarium show teaches about meteors, meteorites, asteroids, and comets. It includes results from NASA missions and about the dangers they can pose to life on Earth. It is created for full-dome theaters but can also be shown in flat version for TVs and computer monitors. Shows the effects of the Chixulub and Tungusta events, plus the Pallasite impact that resulted in the Brenham meteorite fall. Describes ways that asteroid hunters seek new objects in the Solar System, and how ground-penetrating radar is used to find meteorites that have reached the Earth's surface and ancient craters under the desert. Narrated by astronaut Tom Jones, it also discusses ways that humans might try to deflect an asteroid or comet that is on a collision course with Earth. Created for informal science venues (digital planetariums), it is also useful as ancillary material for middle school science. Created under NASA Cooperative Agreement NCC5-316 to Rice University in conjunction with the Houston Museum of Natural Science as part of the "Immersive Earth" project, part of the REASoN program.

  18. Visible Earth

    NSDL National Science Digital Library

    2001-01-01

    This Web site provides a searchable directory of NASA Earth science images, animations and data visualizations. Most resources are available digitally at multiple resolutions, with captions and metadata. Users can search the database using full text and advanced searches by topic, keyword, sensor, location, parameter, and dates.

  19. Earth Walk

    NSDL National Science Digital Library

    2012-06-26

    In this hands-on and feet-on excursion, learners take a science walk to visualize the planet's immense size and numerous structures, without the usual scale and ratio dimensions found in most textbooks. Learners also compare their body's height to a scaled-down Earth.

  20. 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.