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1

Masters Project Integrated Optical Microsystems Group (IOMS) Optical Characterization of Rare Earth Doped Waveguides and Lasers  

E-print Network

such as Al2O3 and Y2O3 doped with rare earth elements are potentially capable of providing the requiredMasters Project ­ Integrated Optical Microsystems Group (IOMS) Optical Characterization of Rare Earth Doped Waveguides and Lasers Introduction Active micro and nano-photonic devices are considered

Al Hanbali, Ahmad

2

Lateral color integration on rare-earth-doped GaN electroluminescent thin films  

Microsoft Academic Search

Lateral color integration has been obtained using GaN thin films doped with Er and Eu. These rare-earth doped GaN (GaN:RE) films were grown on Si (111) substrates by molecular beam epitaxy. Independent red and green emissions have been obtained from side-by-side Er and Eu electroluminescent devices. Photoluminescence and electroluminescence operation show green emissions at 537 and 558 nm from Er-doped

D. S. Lee; A. J. Steckl

2002-01-01

3

Lateral color integration on rare-earth-doped GaN electroluminescent thin films  

NASA Astrophysics Data System (ADS)

Lateral color integration has been obtained using GaN thin films doped with Er and Eu. These rare-earth doped GaN (GaN:RE) films were grown on Si (111) substrates by molecular beam epitaxy. Independent red and green emissions have been obtained from side-by-side Er and Eu electroluminescent devices. Photoluminescence and electroluminescence operation show green emissions at 537 and 558 nm from Er-doped GaN and red emission at 621 nm from Eu-doped GaN. Two patterning fabrication techniques have been investigated to obtain lateral integration: (a) use of shadow masks during 400 °C growth of GaN:RE films; (b) photoresist liftoff in conjunction with <100 °C GaN:RE growth. Devices fabricated by the shadow mask method were bright enough to be detected under the ambient light at a bias of 30 V. The GaN:RE films were clear and their surfaces were smooth with nanoscale GaN grains. The root mean square surface roughness was measured to be 5-10 nm.

Lee, D. S.; Steckl, A. J.

2002-03-01

4

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

E-print Network

Lateral color integration on rare-earth-doped GaN electroluminescent thin films D. S. Lee and A. J December 2001; accepted for publication 29 January 2002 Lateral color integration has been obtained using °C growth of GaN:RE films; b photoresist liftoff in conjunction with 100 °C GaN:RE growth. Devices

Steckl, Andrew J.

5

Masters Project Integrated Optical Microsystems Group (IOMS) Design and Optical Characterization of Rare Earth Doped On-chip Waveguide  

E-print Network

of Rare Earth Doped On-chip Waveguide Laser Components Introduction Active micro and nano-photonic devices materials doped with rare earth elements, in particular Er:Al2O3, are potentially very useful

Al Hanbali, Ahmad

6

Rare earth-doped glass microbarcodes  

PubMed Central

The development of ultraminiaturized identification tags has applications in fields ranging from advanced biotechnology to security. This paper describes micrometer-sized glass barcodes containing a pattern of different fluorescent materials that are easily identified by using a UV lamp and an optical microscope. A model DNA hybridization assay using these “microbarcodes” is described. Rare earth-doped glasses were chosen because of their narrow emission bands, high quantum efficiencies, noninterference with common fluorescent labels, and inertness to most organic and aqueous solvents. These properties and the large number (>1 million) of possible combinations of these microbarcodes make them attractive for use in multiplexed bioassays and general encoding. PMID:12515864

Dejneka, Matthew J.; Streltsov, Alexander; Pal, Santona; Frutos, Anthony G.; Powell, Christy L.; Yost, Kevin; Yuen, Po Ki; Muller, Uwe; Lahiri, Joydeep

2003-01-01

7

Scintillation of rare earth doped fluoride nanoparticles  

SciTech Connect

The scintillation response of rare earth (RE) doped core/undoped (multi-)shell fluoride nanoparticles was investigated under x-ray and alpha particle irradiation. A significant enhancement of the scintillation response was observed with increasing shells due: (i) to the passivation of surface quenching defects together with the activation of the REs on the surface of the core nanoparticle after the growth of a shell, and (ii) to the increase of the volume of the nanoparticles. These results are expected to reflect a general aspect of the scintillation process in nanoparticles, and to impact radiation sensing technologies that make use of nanoparticles.

Jacobsohn, L. G.; McPherson, C. L.; Sprinkle, K. B.; Ballato, J. [Center for Optical Materials Science and Engineering Technologies (COMSET), and School of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634 (United States); Yukihara, E. G. [Physics Department, Oklahoma State University, Stillwater, Oklahoma 74078-3072 (United States); DeVol, T. A. [Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, South Carolina 29634-0905 (United States)

2011-09-12

8

Tunable, rare earth-doped solid state lasers  

DOEpatents

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.

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

1980-01-01

9

Raman spectroscopy of rare earth doped silver halide crystals  

NASA Astrophysics Data System (ADS)

The phonon energy of rare earth doped silver halide crystals was investigated using Raman spectroscopy. An additional phonon vibrational mode was observed and attributed to localized defect vibrational modes. Good agreement was found between the measured and the predicted frequencies of the local modes. These additional low energy (65-80 cm-1) vibrational modes do not increase the thermal quenching of mid-IR luminescence of the rare earth ions in silver halide crystals. The rare earth doped silver halide crystals are suitable for the fabrication of mid-IR solid state lasers and fiber lasers due to their extremely low phonon energies.

Shafir, I.; Nagli, L.; Katzir, A.

2009-06-01

10

Regionally Integrated Earth System Modeling  

NASA Astrophysics Data System (ADS)

In this talk, the regional nature of global environmental challenges will be explored. A broad approach is discussed by examining the scientific foundation that is needed to support policy and decision-making, and by seeking to identify some of the most important barriers to progress that are truly scale-dependent. In so doing, the nature of regionally-specific phenomena that are intrinsically part of global environmental changes will be highlighted as a critical part of the global change research agenda. In addition, successfully informing decision-making requires uncertainty characterization of regional Earth system processes and phenomena as well as an understanding of stakeholder needs. Finally, an integrated modeling and observational framework by which progress can be made will be proposed.

Hibbard, K. A.; Janetos, A.; Leung, R.; Clarke, L.; Edmonds, J.; Thomson, A.; Kintner-Meyer, M.; Moss, R.; Rice, J.

2011-12-01

11

Porous silicon - rare earth doped xerogel and glass composites  

NASA Astrophysics Data System (ADS)

The development of components for photonics applications is growing exponentially. The sol-gel method is now recognised as a convenient and flexible way to deposit oxide or glass films on a variety of hosts, including porous silicon. In the present work we incorporated erbium and europium doped xerogel into porous silicon and developed new porous silicon - rare earth doped glass composites. Various characteris-ation techniques including FTIR, Raman Spectroscopy, Thermal Gravimetric Analysis and Scanning Electron Microscopy were employed in this work.

Balakrishnan, S.; Gun'ko, Yurii K.; Perova, T. S.; Rafferty, A.; Astrova, E. V.; Moore, R. A.

2005-06-01

12

Rare-earth doped polymer waveguides and light emitting diodes  

Microsoft Academic Search

Polymer-based optical waveguide amplifiers offer a low-cost alternative for inorganic waveguide amplifiers. Due\\u000a to the fact that their refractive index is almost similar to that of standard optical fibers, they can be easily coupled\\u000a with existing fibers at low coupling losses. Doping the polymer with rare-earth ions that can yield optical gain is\\u000a not straightforward, as the rare-earth salts are

L. H. Slooff

2000-01-01

13

Mechanical stress in rare-earth-doped laser fibers  

NASA Astrophysics Data System (ADS)

Mechanical stress can significantly influence the optical and mechanical properties of fibers. We present results of nondestructive measurements of thermal stress in rare-earth-doped optical fibers, which are related to the doping variations across the fiber cross section and the preparation conditions. The samples are preforms and fibers with a large ytterbium doped core that were prepared by an alternative glass forming process, which is capable to realize bigger ratios of core to cladding diameter than the MCVD-method. To the best of our knowledge, this is the first time measurements of stresses and birefringence were made on such active optical fibers and their preforms. The results are compared to previous results on ytterbium-doped samples fabricated by the MCVD-technology. From the resultant stress profile, we could calculate the stress induced index changes that are relevant for the light propagation in optical fibers, and discuss the reasons for the observed mechanical stress. In addition, we could evaluate the samples regarding their changes in thermal expansion coefficient induced by doping with one or more oxides in several concentrations and different ratios. We confirmed our earlier result that the active doping component ytterbium generates much higher stress than other common dopants like aluminum, phosphorus or boron.

Just, Florian; Müller, Hans Rainer; Grimm, Stephan; Bartelt, Hartmut

2009-02-01

14

Rare Earth Doped High Temperature Ceramic Selective Emitters  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

15

Magnetic property improvement of niobium doped with rare earth elements  

NASA Astrophysics Data System (ADS)

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.

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

16

Promising wastewater treatment using rare earth-doped nanoferrites  

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

17

Rare earth doped zinc oxide varistors  

DOEpatents

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.

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

1998-12-29

18

Twin-Core Rare-Earth Doped Nonlinear Fiber Devices  

NASA Astrophysics Data System (ADS)

Twin-core rare-earth doped nonlinear optical fiber devices, including optical fiber switches, optical fiber filters and optical fiber amplifiers, are explored in this thesis. An analytical method resorting to the energy E of an oscillator with perturbed nonlinear potential is proposed and demonstrated for investigating the bifurcation and the near-separatrix-crossing of a nonlinear fiber coupler with loss and saturable nonlinearity. Two characteristic equations for bifurcation and near-separatrix-crossing are obtained, from which the critical optical power, the minimum coupling length and the maximum coupler length can be decided. The all-optical fiber switch constructed from a twin-core erbium-doped fiber is studied theoretically and experimentally. The switching behaviour is simulated theoretically, and a switching fraction of 65% is obtained experimentally. The advantage of this switch is that it requires only a fraction of a milliwatt of input power to switch. The transient switching experiment indicates that the switching response time is in the order of 10 ms. Furthermore, a compact optical switching device through the use of a twin-core Nd^{3+ }-doped fiber coupler and a laser diode is demonstrated. Steady state switching and transient switching is obtained. The switching power is 5.6 mW and the switching speed is 500 mus which is 20 times faster than that in twin-core Er^{3+ }-doped fiber couplers. In addition to the passive fiber devices, an active twin-core rare-earth doped fiber coupler is proposed and studied theoretically. It is demonstrated both numerically and experimentally that a narrow-band wavelength filter/demultiplexer with gain can be constructed from a twin-core rare-earth -doped fiber. The experimental bandwidth obtained is 6.5 nm. In addition, the filtered signal experiences a gain of 20 dB instead of attenuation. A preliminary study of using light to control light has been carried out. Optical signal switching through the use of a pump light is observed. Finally, a theoretical model has been proposed in that a twin-core erbium-doped fiber can be used as an optical fiber amplifier. Its gain spectrum is flat within 2.5 dB in a bandwidth of 30 nm. This gain spectrum can be adjusted continuously by varying the pump power launched into one of the cores.

Wu, Bin

19

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

E-print Network

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

Moshchalkov, Victor V.

20

Rare Earth Doped Fiber Amplifiers for the First Telecommunication Window  

NASA Astrophysics Data System (ADS)

A complete experimental and theoretical study of rare earth doped fiber-optic amplifiers for the first tele-communication window has been made. The thulium doped fluoride fiber amplifier is shown to provide amplification in the 800nm-820nm signal region. A complete steady state theoretical model has been presented and the model has been experimentally verified. The model predicts the gain, noise figure and the amplified spontaneous emission in the 800nm, 1470nm, 1900nm and 2300nm bands. The effect of population trapping at the ^3F_4 energy level of thulium ion is also shown with the help of the model. It has been shown that about 5 -15%o of the population is trapped at the ^3F _4 energy level. We have also shown theoretically, the expected gain and noise performance of Thulium doped fluoride fiber amplifiers pumped in the 680nm absorption band. The maximum gain at 806nm is slightly lower than with comparable 780 nm pumping. The gain bandwidth is however found to increase with 680nm pumping. The higher ASE at shorter wavelengths (<806nm) reduces the gain at the peak wavelength (806nm). This is a result of the better inversion with three level pumping at 680nm as compared to two level resonant pumping at 780nm. We report an efficient single mode erbium doped flouride fiber amplifier in the 850nm signal band for the first time. The amplification is through an up-conversion process. The erbium doped flouride fiber amplifier was pumped with an estimated pump power of 35mW at 792nm. We have also considered a theoretical model for a single mode erbium doped fluoride fiber amplifier. Efficient amplification occurs because of the strong excited state absorption at the pump wavelength from the ^4I_{13/2} energy level.

Sridhar, Balakrishnan

21

Rare Earth doped nanoparticles in imaging and PDT  

PubMed Central

Nanoparticles doped with rare earth ions for biomedical imaging and infrared photodynamic therapy (IRPDT) have been synthesized, characterized, and compared. Specifically, these nanoparticles utilize two primary modalities: near infrared excitation and emission for imaging, and near infrared upconversion for photodynamic therapy. These nanoparticles are optimized for both their infrared emission and upconversion energy transfer to a photoactive agent conjugated to the surface. Finally, these nanoparticles are tested for toxicity, imaged in cells using the near infrared emission pathway, and used for selective killing of cells through the upconversion driven IRPDT.

Yust, Brian G.; Sardar, Dhiraj K.; Mimun, Lawrence C.; Gangadharan, Ajith K.; Tsin, Andrew T.

2014-01-01

22

Multicomponent, Rare-Earth-Doped Thermal-Barrier Coatings  

NASA Technical Reports Server (NTRS)

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.

Miller, Robert A.; Zhu, Dongming

2005-01-01

23

Growth of rare-earth doped oxyde nanoparticles in silica fibers Valrie Mauroy*  

E-print Network

for applications such as fiber amplifiers. 2 EXPERIMENTAL DETAILS Preforms were fabricated by the conventional MVCDGrowth of rare-earth doped oxyde nanoparticles in silica fibers Valérie Mauroy* , Wilfried Blanc7336 Parc Valrose, 06180 Nice Cedex 2 ABSTRACT Rare earth (RE) doped silica-based optical fibers

Paris-Sud XI, Université de

24

Earth System Science at Cornell Earth system sciences looks at the integrated whole of the planet,  

E-print Network

Earth System Science at Cornell Earth system sciences looks at the integrated whole of the planet for earth system science range from nm to 1000's of kilometers. Advancing earth system science requires whose work contributes to an understanding of earth system science. We think that organizing ourselves

Angenent, Lars T.

25

Rare-earth doped polymer waveguides and light emitting diodes  

NASA Astrophysics Data System (ADS)

Polymer-based optical waveguide amplifiers offer a low-cost alternative for inorganic waveguide amplifiers. Due to the fact that their refractive index is almost similar to that of standard optical fibers, they can be easily coupled with existing fibers at low coupling losses. Doping the polymer with rare-earth ions that can yield optical gain is not straightforward, as the rare-earth salts are poorly soluble in the polymer matrix. This thesis studies two different approaches to dope a polymer waveguide with rare-earth ions. The first one is based on organic cage-like complexes that encapsulate the rare-earth ion and are designed to provide enough coordination sites to bind the rare-earth ion and to shield it from the surrounding matrix. Chapter 2 describes the optical properties of Er-doped organic polydentate cage complexes. The complexes show clear photoluminescence at 1.54 mm with a bandwidth of 70 nm, the highest reported for an erbium-doped material so far. The luminescence lifetime is very short (~1 ms) due to coupling to vibrational overtones of O-H and C-H bonds. Due to this short luminescence lifetime, high pump powers (~1 W) are needed for optical gain in a waveguide amplifier based on these complexes. The pump power can be reduced if the Er is excited via the aromatic part of the complex, which has a higher absorption cross section. In Chapter 3 a lissamine-functionalised neodymium complex is studied in which the highly absorbing lissamine acts as a sensitiser. The lissamine is first excited into the singlet state from which intersystem crossing to the triplet state can take place. From there it can transfer its energy to the Nd ion by a Dexter transfer mechanism. Room-temperature photoluminescence at 890, 1060, and 1340 nm from Nd is observed, together with luminescence from the lissamine sensitiser at 600 nm. Photodegradation of the lissamine sensitiser is observed, which is studied in more detail in Chapter 4. The observed change in time of the spectral shape of the lissamine luminescence can be explained by assuming that two types of complexes exist. One type in which energy transfer to the Nd3+ ion can take place, and one that is not coupled to Nd. The highly absorbing sensitiser makes the standard butt-end coupling of the pump light into a waveguide amplifier impractical. The pump power can be used more efficiently by using a novel coupled waveguide system as described in Chapter 5. This employs gradual evanescent field coupling between parallel pump and signal waveguides. An alternative approach to make a rare-earth doped polymer waveguide is by combining the excellent properties of SiO2 as a host for the rare-earth with the easy processing of polymers. The optical properties of Er-doped silica films made by an acid-catalysed sol-gel synthesis are reported in Chapter 6. The Er exhibits long luminescence lifetimes of 10-12 ms, which indicates that OH from the wet chemical synthesis is successfully removed during the vacuum anneal treatment. Using a base-catalysed sol-gel synthesis, silica colloidal spheres with diameters of 175 and 340 nm were grown. Chapter 7 describes the luminescence properties of the 340 nm spheres, implanted with Er up to concentrations of 1.0 at.%. The Er shows a very long luminescence lifetime of 17 ms, and the radiative lifetime is estimated to be 20-22 ms, indicating a high quantum efficiency. This long luminescence lifetime is partly due to the low local optical density of states (DOS) in the free standing silica colloids. Optical gain calculations are made for the colloid/polymer waveguide that predicts a net gain of 8.7 dB at a pump power of 30 mW, for a 15 cm long waveguide. Such a length can be rolled up on an area of 16 mm2. In Chapter 8, calculations of the DOS are described for thin films as well as the spherical colloids. By comparing the calculation with experimentally probed decay rates, radiative and non-radiative components in the decay of Er are determined. Besides optical pumping of planar waveguide amplifiers it would be interesting if electrical pumping could b

Slooff, L. H.

2000-11-01

26

Thermopower studies of rare earth doped lanthanum barium manganites  

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

27

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

SciTech Connect

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.

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

28

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

E-print Network

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 ...

Vanhoutte, Michiel

29

Quantum Computing Hardware based on Rare-Earth-Ion Doped Whispering-Gallery Mode Resonators.  

E-print Network

??Rare-earth-ion doped crystals are an interesting system for quantum computing investigations due to their long optical and hyperfine coherence times. In particular, the ground-state coherence… (more)

McAuslan, David Lee

2011-01-01

30

Sensing Using Rare-Earth-Doped Upconversion Nanoparticles  

PubMed Central

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

Hao, Shuwei; Chen, Guanying; Yang, Chunhui

2013-01-01

31

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

32

The integrated Regional Earth System Model  

NASA Astrophysics Data System (ADS)

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.

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

33

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

E-print Network

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

Boyer, Edmond

34

Characterization of Sol-Gel derived scintillating LuBO3 films doped with rare earth ions.  

E-print Network

Characterization of Sol-Gel derived scintillating LuBO3 films doped with rare earth ions. C. Mansuy-669" DOI : 10.1016/j.tsf.2005.12.235 #12;Abstract Rare earth doped LuBO3 thin films have been prepared, 81.20. Fw, Keywords : Sol-Gel, Scintillators, XPS, RBS, Rare earth ions, Luminescence hal-00154764

Boyer, Edmond

35

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

E-print Network

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

Pennycook, Steve

36

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

PubMed

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

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

2013-10-11

37

Integrating Live Access Server into Google Earth  

NASA Astrophysics Data System (ADS)

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.

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

2006-12-01

38

Study on rare-earth-doped type-I germanium clathrates  

NASA Astrophysics Data System (ADS)

The synthesis of rare-earth clathrates RExBa8-xGa16Ge30 is a challenging task. The Group IV clathrates with rare-earth doping are hardly to be experimentally prepared, except Eu clathrate. In the current study, the first-principle method based on the density functional theory was implemented. The effects of the various RE elements doping on the binding energy and chemical reaction drive energy were studied by optimizing the phase structure. The energy calculations suggest that it is difficult to synthesize RE clathrates without Ga doping. The function of Ga doping is to effectively increase the drive chemical reaction in order to synthesize the clathrates. The simulation shows that, besides Eu, other rare-earth elements, such as Sm, Nd, and Yb can also enter cage lattice in the considering of drive energy, thus making it possible to synthesize the (RE,Ba)8Ge30Ga16 clathrates.

Zhu, Xiaohui; Chen, Ning; Liu, Lihua; Li, Yang

2012-04-01

39

Influence of Rare Earth Doping on the Structural and Catalytic Properties of Nanostructured Tin Oxide  

NASA Astrophysics Data System (ADS)

Nanoparticles of tin oxide, doped with Ce and Y, were prepared using the polymeric precursor method. The structural variations of the tin oxide nanoparticles were characterized by means of nitrogen physisorption, carbon dioxide chemisorption, X-ray diffraction, and X-ray photoelectron spectroscopy. The synthesized samples, undoped and doped with the rare earths, were used to promote the ethanol steam reforming reaction. The SnO2-based nanoparticles were shown to be active catalysts for the ethanol steam reforming. The surface properties, such as surface area, basicity/base strength distribution, and catalytic activity/selectivity, were influenced by the rare earth doping of SnO2 and also by the annealing temperatures. Doping led to chemical and micro-structural variations at the surface of the SnO2 particles. Changes in the catalytic properties of the samples, such as selectivity toward ethylene, may be ascribed to different dopings and annealing temperatures.

Fajardo, Humberto V.; Longo, Elson; Probst, Luiz F. D.; Valentini, Antoninho; Carreño, Neftalí L. V.; Nunes, Michael R.; Maciel, Adeilton P.; Leite, Edson R.

2008-05-01

40

DFT Calculations using WIEN2K to determine oxygen defect structure of rare earth doped ceria  

E-print Network

We perform density functional calculations using the program WIEN2K in order to study oxygen vacancies in rare earth doped ceria. The calculation for all rare earth elements were prepared, however only those foe Cadmium and Europium were performed due to lack of time. Also a short description of my stay at CERN was presented

Khalife, Ali Rida

2014-01-01

41

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

E-print Network

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

Paris-Sud XI, Université de

42

Specific mode output from multimode fiber oscillators by designing rare earth doping profiles  

NASA Astrophysics Data System (ADS)

Based on rate equations, a theoretical model of a fiber oscillator with a multimode gain fiber was built. We studied the effect of the rare earth doping profile in the core on the output characteristics of the multimode fiber oscillator. The results indicated that a pure fundamental mode can be obtained by partly doping the core of the large mode area (LMA) ytterbium doped fiber (YDF) in the fiber laser. Furthermore, a sole specific high-order mode can also be implemented by tailoring the rare earth doping profile according to the simulations. The mode coupling effect was also taken into account in the model. In spite of the mode coupling effect, the specific mode was able to dominate in the output of the fiber laser by utilizing the designed LMA YDF.

Wang, Wen-Liang; Huang, Liang-Jin; Leng, Jin-Yong; Guo, Shao-Feng; Jiang, Zong-Fu

2014-09-01

43

Multiferroism in rare earth metals-doped BiFeO3 nanowires  

NASA Astrophysics Data System (ADS)

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.

Lotey, Gurmeet Singh; Verma, N. K.

2013-08-01

44

NIR Persistent Luminescence of Lanthanide Ion-Doped Rare-Earth Oxycarbonates: The Effect of Dopants.  

PubMed

A series of luminescent rare-earth ion-doped hexagonal II-type Gd oxycarbonate phosphors Gd2-xRExO2CO3 (RE = Eu(3+), Yb(3+), Dy(3+)) have been successfully synthesized by thermal decomposition of the corresponding mixed oxalates. The Yb(3+) doped Gd-oxycarbonate has evidenced a high persistent luminescence in the NIR region, that is independent from the temperature and makes this materials particular attractive as optical probes for bioimaging. PMID:25285437

Caratto, Valentina; Locardi, Federico; Costa, Giorgio Andrea; Masini, Roberto; Fasoli, Mauro; Panzeri, Laura; Martini, Marco; Bottinelli, Emanuela; Gianotti, Enrica; Miletto, Ivana

2014-10-22

45

Dopant distributions in rare-earth-doped alumina  

Microsoft Academic Search

The distribution of yttrium and lanthanum dopants has been mapped in yttrium- and lanthanum-doped polycrystalline aluminas using imaging secondary-ion mass spectrometry (imaging-SIMS). Both dopants segregate to grain boundaries and pore surfaces. On average, yttrium occupies 7.1%--9.0% of the available grain-boundary cation sites, whereas lanthanum occupies only 2.0%--5.2%. In 1,000-ppm-yttrium-doped alumina, an abundance of yttrium aluminum garnet precipitates also is observed.

A. M. Thompson; H. M. Chan; M. P. Harmer; D. B. Williams; K. K. Soni; J. M. Chabala; R. Levi-Setti

1997-01-01

46

Earth System Science: An Integrated Approach.  

ERIC Educational Resources Information Center

Details how an understanding of the role played by human activities in global environmental change has emerged. Presents information about the earth system provided by research programs. Speculates about the direction of future research. (DDR)

Environment, 2001

2001-01-01

47

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

NASA Astrophysics Data System (ADS)

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

Peyghan, Ali Ahmadi; Noei, Maziar

2014-01-01

48

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

PubMed

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

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

2013-12-13

49

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

E-print Network

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%.

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

2014-02-21

50

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

E-print Network

Supplementary Information: The Grid ENabled Integrated Earth system modelling (GENIE) framework T. Shepherd P. J. Valdes§ G. Williams§ M. S. Williamson A. Yool January 31, 2007 Abstract The Grid ENabled for Global Change, Yokohama, Japan Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR

Edwards, Neil

51

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

SciTech Connect

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)

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

52

Internal and External Radiative Decay Engineering of Rare Earth Doped Nanocrystalline Sesquioxides  

NASA Astrophysics Data System (ADS)

Rare earth (RE) based sesquioxide structures (RE2O3), when doped judiciously with trivalent RE ions, are not susceptible to photobleaching and offer many sharp electronic transitions with excited state lifetimes on the order of milliseconds. Additionally, internal lattice engineering of the host offers several distinct crystal phases which may be synthesized easily by tuning the host RE. Similarly, the proximity of noble metals to trivalent rare earth ions has shown promise as a sensitizer that greatly enhances the photoluminescence of the rare earth ion. More recently, results have been reported for gold coated silica dielectric nanoparticles which have been modeled extensively and shown to act as a nano-antenna, enhancing the electric field inside the dielectric core. This short range antenna effect offers radiative decay engineering at the external level. Here, we report the internal and external radiative decay engineering of several rare earth doped sesquioxide and metallic hetero-nanostructures and discuss the nanoscale physics of these systems.

Dennis, Robert; Nash, Kelly; Zhang, Maogen; Gorski, Waldemar; Sardar, Dhiraj

2010-10-01

53

Growth and characterization of rare earths doped triglycine sulfate crystals  

NASA Astrophysics Data System (ADS)

Ferroelectric triglycine sulfate (TGS) single crystals have been grown by a temperature-lowering technique from the aqueous solution by doping with samarium sulfate, ytterbium sulfate and terbium sulfate in the ferroelectric phase. The effects of these different dopants on the morphology, growth and various properties such as dielectric, pyroelectric and piezoelectric of doped TGS crystals have been investigated. The decrease in values of dielectric constant and pyroelectric coefficient is observed while the dielectric loss has increased. Using these parameters, figure-of-merits for their use in infrared sensors have also been reported and compared with pure TGS crystal. The Vickers's hardness of doped TGS crystals along (0 1 0) crystallographic face has increased.

Batra, A. K.; Guggilla, Padmaja; Cunningham, Dewanna; Aggarwal, M. D.; Lal, R. B.

2006-01-01

54

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

Microsoft Academic Search

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,

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

2009-01-01

55

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

Microsoft Academic Search

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

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

1992-01-01

56

Preparing nano-crystalline rare earth doped WC\\/Co powder by high energy ball milling  

Microsoft Academic Search

The nano-crystalline rare earth doped WC\\/Co powder was prepared by high energy ball milling. The nano-crystalline powders were characterized by means of XRD (X-ray diffraction), SEM (scanning electron microscope) and DTA (differential thermal analysis). The results show that adding trace rare earth elements into carbides is effective to minish the grain size of WC\\/Co powder. The grain size of rare

Sha Liu; Ze-Lan Huang; Gang Liu; Gui-Bin Yang

2006-01-01

57

Rare-earth-doped GaN: growth, properties, and fabrication of electroluminescent devices  

Microsoft Academic Search

A review 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 followed by radiative RE relaxation. By appropriately choosing the RE dopant, narrow linewidth emission can be obtained at selected wavelengths from the ultraviolet to the infrared. The

Andrew J. Steckl; Jason C. Heikenfeld; Dong-Seon Lee; Michael J. Garter; Christopher C. Baker; Yongqiang Wang; Robert Jones

2002-01-01

58

Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition  

E-print Network

Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor weaken the fibers, and it introduces certain 2 #12;complexicities in the global fabrication process report deals with silica-based TGC fiber preforms prepared by the well-known MCVD (modified chemical

Paris-Sud XI, Université de

59

Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition  

E-print Network

Rare earth (RE) doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of post-ceramming. The main characteristics of the RE-doped oxyde nanoparticles namely, their density and mean diameter in the fibers are dictated by the concentration of alkaline earth element used as phase separating agent. Magnesium and erbium co-doped fibers were fabricated. Optical transmission in term of loss due to scattering as well as some spectroscopic characteristics of the erbium ions was studied. For low Mg content, nano-scale particles could be grown with and relatively low scattering losses were obtained, whereas large Mg-content causes the growth of larger particles resulting in much higher loss. However in the latter case, certain interesting alteration of the spectroscopic properties of the erbium ions were observed. These initial studies should be useful in incorporati...

Blanc, Wilfried; Nguyen, Luan; Bhaktha, S N B; Sebbah, Patrick; Pal, Bishnu P; Dussardier, Bernard

2011-01-01

60

Integrated Earth Systems: Confronting Global Change  

NSDL National Science Digital Library

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.

Mosley-Thompson, Ellen; University, Ohio S.

61

Effects of rare earth doping on the superconducting properties of MgB 2  

NASA Astrophysics Data System (ADS)

Doping effects of rare earth oxides (REO y: RE = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) on the superconducting properties of MgB 2 were investigated. Large fraction of the added RE turned into impurity phases: REB 6 for RE = La-Gd and Yb, and REB 4 for RE = Tb-Tm and Lu. We observed an increase in c-axis length from 3.523 to 3.533 Å when doped with Lu. Clear decreases in transition temperatures were observed in samples doped with Sm, Eu, Gd, Tm, Yb and Lu, indicating that these elements were successfully substituted for Mg. The decreases in Tc were most drastic in Yb-doped samples ( Tc ? 32 K).

Katsura, Y.; Shimoyama, J.; Yamamoto, A.; Horii, S.; Kishio, K.

2007-10-01

62

Enhanced superconductivity by rare-earth metal doping in phenanthrene.  

PubMed

We successfully synthesized La- and Sm-doped phenanthrene powder samples and observed superconductivity in them at T(c) around 6 K. The T(c)s are 6.1 K for La(1) phenanthrene and 6.0 K for Sm(1) phenanthrene, which are enhanced by about 1 and 0.5 K compared to those in A(3) phenanthrene (A = K and Rb) and in Ae(1.5) phenanthrene (Ae = Sr and Ba) superconductors, respectively. The superconductive shielding fractions for La(1) phenanthrene and Sm(1) phenanthrene are 46.1% and 49.8% at 2 K, respectively. The small effect of doping with the magnetic ion Sm(3+) on T(c) and the positive pressure dependence coefficient of T(c) strongly suggest unconventional superconductivity in the doped phenanthrene superconductors. The charge transfer to organic molecules from dopants of La and Sm induces a redshift of 7 cm(-1) per electron for the mode at 1441 cm(-1) in the Raman spectra, which is almost the same as those observed in A(3) phenanthrene (A = K and Rb) and Ae(1.5) phenanthrene (Ae = Sr and Ba) superconductors. PMID:22872048

Wang, X F; Luo, X G; Ying, J J; Xiang, Z J; Zhang, S L; Zhang, R R; Zhang, Y H; Yan, Y J; Wang, A F; Cheng, P; Ye, G J; Chen, X H

2012-08-29

63

A combined DFT + U and Monte Carlo study on rare earth doped ceria.  

PubMed

We investigate the dopant distribution and its influence on the oxygen ion conductivity of ceria doped with rare earth oxides by combining density functional theory and Monte Carlo simulations. We calculate the association energies of dopant pairs, oxygen vacancy pairs and between dopant ions and oxygen vacancies by means of DFT + U including finite size corrections. The cation coordination numbers from ensuing Metropolis Monte Carlo simulations show remarkable agreement with experimental data. Combining Metropolis and Kinetic Monte Carlo simulations we find a distinct dependence of the ionic conductivity on the dopant distribution and predict long term degradation of electrolytes based on doped ceria. PMID:24477833

Grieshammer, Steffen; Grope, Benjamin O H; Koettgen, Julius; Martin, Manfred

2014-06-01

64

Strongly luminescent rare-earth-ion-doped DNA-CTMA complex film and fiber materials  

NASA Astrophysics Data System (ADS)

A rare-earth chelate, Europium 6,6.7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5,-octanedionate, (Eu3+-FOD) doped DNACTMA complex as fiber and film materials was prepared by casting solution method and gel-spinning method. The Eu-FOD-DNA-CTMA complex was luminescent and has 750 ?s of fluorescence lifetime, sharply-spiked emission spectra, excellent film and fiber formability, moderate absorption (40000M-1cm-1) at 327 nm and high quantum yield forlanthanide emission. By comparison of fluorescence lifetime of Eu-FOD doped DNA-CTMA solid matrix with that of Eu-FOD doped in PMMA, it was clear that energy transfer from DNA to FOD leads to enhancement of fluorescence emission at 613 nm. Analysis results for fluorescence spectra and fluorescence relaxation time of Eu3+ doped in the materials indicated that Eu3+-FOD is chemically bond within the DNA-CTMA matrix. Amplified spontaneous emission (ASE) at 612 nm by pumping with UV laser (355 nm) was observed in the materials. Fluorescence lifetime of the Eu-FOD doped in the DNA-CTMA solid matrix was evaluated to be 750 ?s, which is ca. 230?s longer than that of Eu-FOD doped in PMMA solid matrix. Efficient Energy transfer from base of DNA to FOD, then to Eu, occurred when irradiated by UV light or 355 laser beams.

Wang, Lili; Ishihara, Koki; Izumi, H.; Wada, M.; Zhang, Gongjian; Ishikawa, T.; Watanabe, A.; Horinouchi, Suguru; Ogata, Naoya

2002-08-01

65

Rare-earth doped Si-rich ZnO for multiband near-infrared light emitting devices  

NASA Astrophysics Data System (ADS)

Transparent Conductive Oxides (TCOs) are a broad class of organic and inorganic materials exhibiting both optical transparency and electrical conductivity simultaneously. TCOs are utilized as top-con tact passive layers in a number of optoelectronic devices, including flat panel displays and solar cells. Recently, they are also attracting considerable attention as an active platform for a wide range of novel device applications. Zinc oxide (ZnO) is the most promising candidate for optoelectronic integration due to its low cost and Si compatibility. Moreover, it is a biocompatible material and possibly biodegradable. We fabricated rare earth-doped Si-rich ZnO thin films through magnetron sputtering and we investigate their near-infrared emission properties under both optical and electrical injection. Er and Nd efficient (3ms RT lifetime) radiative transitions were simultaneously activated due to energy transfer via the ZnO direct bandgap and its luminescent defect centers. Moreover, by incorporating Si atoms, we demonstrate Si-mediated enhancement of light emission in Er-doped ZnO, and electroluminescence. We fabricated a proof-of-concept 1.55?m-electroluminescent device with record low turn-on voltage (1.5V) in Er-doped Si-rich ZnO at room temperature. These results pave the way to novel Si-compatible light emitters that leverage the optically transparent and electrically conductive ZnO matrix for multiband near-IR telecom and bio-compatible applications.

Pecora, Emanuele Francesco; Murphy, Thomas Ian; Dal Negro, Luca

2013-03-01

66

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

NASA Astrophysics Data System (ADS)

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

Ballance, John

1994-02-01

67

Multicolor Up-Conversion Luminescence in Rare-Earth Doped NaLaF4  

NASA Astrophysics Data System (ADS)

In this work we tried to achieve multicolor up-conversion luminescence in low phonon energy material NaLaF4 doped with different Er3+ Tm3+ and Yb3+ concentrations. Up-conversion luminescence was measured and main luminescence bands from Er3+ and Tm3+ in red, green and blue spectral regions were observed. The relative intensities of the luminescence bands could be changed by changing the doping levels of rare-earth ions. Changes in the up-conversion luminescence color could be achieved by applying different infrared pump power density. The color coordinates of the multicolor up-conversion luminescence depending on doping level as well as on the pump power density were presented in CIE (x, y) chromaticity diagram (1931).

Grube, J.; Doke, G.; Voss, M.; Sarakovskis, A.; Springis, M.

2011-06-01

68

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

PubMed

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

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

2010-10-01

69

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

PubMed

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

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

2014-10-01

70

Photon echoes in an amplifying rare-earth-ion-doped crystal.  

PubMed

We report what we believe is the first experimental demonstration of photon echoes in an amplifying rare-earth-ion-doped crystal. Population inversion is achieved by optical pumping, which yields high-power photon echoes, with an energy gain of as much as a factor of 5. Effects of the pump on the photon echo process highlight the advantages of an amplifying crystal. New questions concerning the optical dephasing mechanisms in Er3+:YSO have arisen. PMID:15981509

Crozatier, V; Gorju, G; Bretenaker, F; Le Gouët, J L; Lorgeré, I; Baldit, E

2005-06-01

71

Gamma-Radiation-Induced Photodarkening in Unpumped Optical Fibers Doped With Rare-Earth Constituents  

Microsoft Academic Search

Fibers doped with rare-earth constituents such as Er3+ and Yb3+ are exceedingly important to designers of fiber-optical systems due to their ability to amplify signals in the near infra-red, low-absorption regions of conventional silicate fibers. Extending the range of operating conditions for these systems to include adverse radiation environments requires a detailed study of the behavior of the fiber when

Brian P. Fox; Kelly Simmons-Potter; William J. Thomes Jr.; Dahv A. V. Kliner

2010-01-01

72

Heavy metal oxide glasses doped by rare earth ions for optoelectronics  

Microsoft Academic Search

Heavy metal oxide glasses in the system TeO2-PbO-WO3 doped by selected rare earth ions have been presented. The method of their preparation and physical properties were determined. Infrared luminescence of Er3+ and Tm3+ ions embedded in TeO2-PbO-WO3 glass hosts is reported for room and helium liquid temperatures. The substantial influence of energy transfer processes between the glass host and Er3+

Dominik Dorosz; Jan Wasylak

2005-01-01

73

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

E-print Network

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

Steckl, Andrew J.

74

Molecular beam epitaxy (MBE) growth of rare earth doped gallium nitride for laser diode application  

NASA Astrophysics Data System (ADS)

The goal of this dissertation is to demonstrate the visible laser emission from rare earth doped GaN grown on sapphire and silicon substrate. The research presented in this dissertation focused on exploration of RE's physics and laser characteristics and investigating site selective laser emission. In this study, the first visible (red) lasing emission from Eu-doped GaN thin films grown on sapphire substrates was demonstrated. The edge emission fulfills the requirements of stimulated emission properties: super-linear characteristic, spectrum line narrowing, polarization effect, lifetime reduction, and longitudinal modes in a Fabry-Perot cavity. The GaN:Eu active layer has low threshold (˜10kW/cm2) for the onset of lasing. The optical gain and loss are of the order of 50 and 20cm-1, respectively. Growth conditions are investigated for gain enhancement and loss reduction. To obtain the high gain and low loss active layer, N-rich growth conditions are required. Channel waveguide cavities result in 5x increases in gain value compared to planar waveguides. To utilize the performance and flexibility of silicon microelectronics, we used silicon (111) substrate, which incorporated several AlGaN and AIN thin films as buffer, strain compensation and bottom optical cladding layers. With this substrate, we developed the laser structure emitting visible wavelength. We have utilized Eu-doped GaN for the active medium within a structure consisting of a top cladding AlGaN layers grown by MBE on a Si substrate. Stimulated emission (SE) was obtained at room temperature from Eu3+ at 620nm, with a threshold of ˜117kW/cm 2. Values of modal gain and loss of ˜100 and 46 cm-1 were measured. This demonstration indicates that utilizing rare earths a range of lasers on Si can be obtained, covering the UV, visible and IR regions, thus enabling a significant expansion of optoelectronic and microelectronic integration. The dependence of optical modal gain and loss on GaN:Eu growth temperature is also conducted in this dissertation. The modal gain and loss in the GaN:Eu layer were a strong function of the optically active Eu atomic concentration and of the interface quality between the active layer and the top cladding layer, which in turn depended on the growth temperature. Optimum optical properties of maximum modal gain of ˜100 cm-1 and minimum loss of ˜46 cm-1 were obtained for growth at 800°C. We investigated site-specific Eu3+ stimulated emission in GaN:Eu laser structures. Two main Eu sites have been identified from emission peaks associated with the 5D0 to 7F 2 transition during above band gap optical pumping with a pulsed N 2 laser (337 nm): (a) Eux emitting at ˜620 nm---present in short cavities (˜100mum), exhibiting stimulated (side) emission threshold and a fast decay time constant (30-35 mus); (b) Euy emitting at ˜621 nm---present in long cavities (˜7mm) and in surface emission, exhibiting no stimulated emission threshold and a slow decay time constant (150-250 mus).

Park, Jeongho

75

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

PubMed

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

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

2012-01-01

76

Analytical characterization of an end pumped rare-earth-doped double-clad fiber laser  

Microsoft Academic Search

Few steps of derivations on the rate equations have made it clear that the key issue of obtaining an analytical expression for the output laser power, from a double-clad Yb3+-doped fiber laser, is how to integrate the products between the radiation power and its respective loss coefficient for both the pump and laser waves. After examining the approximations adopted in

Zhichun Duan; Liping Zhang; Jianguo Chen

2007-01-01

77

Integrated Earth Observation Data Streams for model benchmarking (Invited)  

NASA Astrophysics Data System (ADS)

In this presentation we present recent advances in generating, characterizing and interpreting data streams which are derived by integrating globally distributed observations of carbon and water fluxes, above-ground and below-ground carbon pools and remote sensing information. Particular emphasis is on the question how these data streams can be used for Earth system model benchmarking. We show that it is crucial to take advantage of the multidimensional nature of arising earth observation data sets which should be matched by models simultaneously, instead of relying on univariate simple comparisons.

Reichstein, M.; Carvalhais, N.; Jung, M.

2013-12-01

78

Crystal-field interaction and oxygen stoichiometry effects in strontium-doped rare-earth cobaltates  

NASA Astrophysics Data System (ADS)

Inelastic neutron scattering was employed to study the crystal-field interaction in the strontium-doped rare-earth compounds RxSr1-xCoO3-z (R=Pr, Nd, Ho, and Er). Particular emphasis is laid on the effect of oxygen deficiencies that naturally occur in the synthesis of these compounds. The observed energy spectra are found to be the result of a superposition of crystal fields with different nearest-neighbor oxygen coordination at the R sites. The experimental data are interpreted in terms of crystal-field parameters, which behave in a consistent manner through the rare-earth series, thereby allowing a reliable extrapolation for rare-earth ions not considered in the present work.

Furrer, A.; Podlesnyak, A.; Frontzek, M.; Sashin, I.; Embs, J. P.; Mitberg, E.; Pomjakushina, E.

2014-08-01

79

New Pr-doped laser crystals of alkaline-earth rare-earth binary tungstates  

SciTech Connect

The lasing properties of Ln{sup 3+} ions in numerous alkaline-earth rare-earth tungstates have been extensively investigated. In this work, undertaken in continuation of previous studies, the authors observed both low-threshold pulsed and quasi-continuous lasing of Pr{sup 3+} ions ({sup 1}D{sub 2} {yields} {sup 3}F{sub 4} transition) in two crystals of this family, KY(WO{sub 4}){sub 2} and KGd(WO{sub 4}){sub 2}.

Kaminskii, A.A. [Shubnikov Institute of Crystallography, Moscow (Russian Federation); Pavlyuk, A.A. [Institute of Inorganic Chemistry, Novosibirsk (Russian Federation)

1995-11-01

80

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

NASA Astrophysics Data System (ADS)

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.

Clark, R. D.

2005-12-01

81

In-volume waveguides by fs-laser direct writing in rare-earth-doped fluoride glass and phosphate glass  

Microsoft Academic Search

Refractive index modifications are fabricated in the volume of rare-earth-doped glass materials namely Er- and Pr-doped ZBLAN (a fluoride glass consisting of ZrF4, BaF2, LaF3, AlF3, NaF), an Er-doped nano-crystalline glass-ceramic and Yb- and Er-doped phosphate glass IOG. Femtosecond laser radiation (tau=500fs, lambda=1045nm, f=0.1-5MHz) from an Ybfiber laser is focused with a microscope objective in the volume of the glass

D. Esser; D. Wortmann; J. Gottmann

2009-01-01

82

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

E-print Network

1251 Magnetic-field effect on the phonon echoes in a rare-earth-doped glass F. Lerbet and G the TLS and the rare-earth ions are perturbed by the magnetic field, whereas the photon echoes arises from frequency range 450-800 MHz. The echo amplitude increases by a factor 3 as the magnetic field increases from

Boyer, Edmond

83

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

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

84

Synthesis and optical properties of sub-micron sized rare earth-doped zirconia particles  

NASA Astrophysics Data System (ADS)

Sub-micron sized crystalline particles of Eu 3+ and Er 3+-doped zirconia (ZrO 2) were prepared via a wet chemical sol-gel route and post synthesis annealing. The doping was achieved by introduction of the respective rare earth salts into the zirconia precursor solution, with insitu generation of sodium chloride for stabilization of the particle surface during growth. A series of materials with differing europium content, nominally 0.3, 3 and 6 mol% within the ZrO 2 lattice, were prepared for respective comparison and characterization of their optical properties following annealing at 700 °C. Average emission lifetimes of up to 2.3 ms were observed for the Eu 3+-doped particles. Particle sizes, approximated from SEM micrographs, were observed in the range 250-400 nm. The synthesis of Er 3+-doped ZrO 2 particles (0.5 mol%) produced 300 nm sized particles which exhibited emission in the visible and infrared regions after annealing at 1000 °C. X-ray diffraction (XRD) with Rietveld analysis for phase quantification, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL) spectra were used to characterize the samples.

Freris, I.; Riello, P.; Enrichi, F.; Cristofori, D.; Benedetti, A.

2011-09-01

85

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

NASA Astrophysics Data System (ADS)

The effect of partial substitution of alkaline earth (AE) ions, Sr2+ and Ca2+, for the rare earth (RE) ions, La3+, Ce3+, Pr3+, and Sm3+, on the physical properties of REVO4 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, REVO4-yttira stabilized zirconia (YSZ) composite anodes exhibited only modest performance when used in SOFCs operating with H2 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.

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

2012-06-01

86

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

PubMed Central

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

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

2013-01-01

87

Electrostatic tuning of Kondo effect in a rare-earth-doped wide-band-gap oxide  

NASA Astrophysics Data System (ADS)

As a long-lived theme in solid-state physics, the Kondo effect reflects the many-body physics involving the short-range Coulomb interactions between itinerant electrons and localized spins in metallic materials. Here we show that the Kondo effect is present in ZnO, a prototypical wide-band-gap oxide, doped with a rare-earth element (Gd). The localized 4f electrons of Gd ions do not produce remanent magnetism, but interact strongly with the host electrons, giving rise to a saturating resistance upturn and negative magnetoresistance at low temperatures. Furthermore, the Kondo temperature and resistance can be electrostatically modulated using electric-double-layer gating with liquid ionic electrolyte. Our experiments provide the experimental evidence of tunable Kondo effect in ZnO, underscoring the magnetic interactions between localized and itinerant electrons and the emergent transport behaviors in such doped wide-band-gap oxides.

Li, Yongfeng; Deng, Rui; Lin, Weinan; Tian, Yufeng; Peng, Haiyang; Yi, Jiabao; Yao, Bin; Wu, Tom

2013-04-01

88

Persistent luminescence of Eu2+ and Na+ doped alkaline earth aluminates  

NASA Astrophysics Data System (ADS)

The luminescence and afterglow properties of the Eu2+ and Na+ doped alkaline earth aluminates, stoichiometric and non-stoichiometric (MxAl2O4:Eu2+, Na+, M=Ca or Sr, x=0.97, 1.00 or 1.03, X-Na=0.02), were studied. Broad band luminescence and afterglow of the Eu2+ ion were observed in the blue (lambda(max) = 440 nm) and green (lambda(max)=520 nm) region for the calcium and strontium aluminates, respectively Both Na+ co-doping and strontium excess quenched the afterglow efficiently The results supported the mechanism of the persistent luminescence where the cation vacancies act as traps. The results for the calcium aluminates were ambiguous, probably due to the slightly larger ionic radius of the Na+ with respect to that of Ca2+. The sodium ions may not fit into the calcium sites and thus form (an) independent compound(s).

Aitasalo, T.; Holsa, J.; Lastusaari, M.; Legendziewicz, J.; Niittykoski, J.

2003-01-01

89

Adaptive Sagnac interferometer with dynamic population grating in saturable rare-earth-doped fiber.  

PubMed

Sagnac fiber interferometer with the dynamic population grating formed in the rare-earth doped fiber is proposed for homodyne adaptive detection of optical phase modulation. The configuration is shown to be a simple all-optical fiber sensor suitable for linear high sensitivity detection of mechanical vibrations, acoustic signals, thermo-optic effect etc. Theoretical consideration shows that the quadratic response of this interferometric configuration associated with the amplitude dynamic grating is observed in the reflected wave mainly, while the recorded phase grating results in the linear energy exchange between the transmitted and reflected from the Sagnac loop light waves. Experiments with the erbium- and ytterbium-doped fiber based adaptive Sagnac configurations (with the operation wavelengths 1485 and 1,064 nm respectively) of the fiber accelerometers confirmed these general conclusions and demonstrated sensitivity of the fiber based interferometric configurations (~3 10?? rad/Hz¹/²) governed basically by the noise of the utilized lasers. PMID:23481961

Rivera, Jorge López; Sánchez, Marcos Plata; Miridonov, Alexei; Stepanov, Serguei

2013-02-25

90

Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO2 fiber  

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

91

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

PubMed

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

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

2014-08-01

92

A study and modeling of Fabry-Perot cavities with rare earth doped fiber  

NASA Astrophysics Data System (ADS)

This paper presents properties of all-optical bistable fibre switch using two fibre Bragg gratings and rare earth elements doped optical fiber. It is not possible to obtain bistable properties at low switching power level in case of a single fibre grating. In this article the method of optical switching that uses all-optical switch has been proposed. It has been achieved by varying the refractive index of nonlinear optical material as a result of light signal amplitude changes. Presented optical bistable device can be used both in contemporary optically switched networks as well as in optoelectronic sensors, owing to their high achievable resolution.

Cieszczyk, S?awomir; Klimek, Jacek; Skorupski, Krzysztof; Kisa?a, Piotr

2014-05-01

93

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

PubMed

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

Schartner, Erik P; Monro, Tanya M

2014-01-01

94

Fabrication of photonic crystals in rare-earth doped chalcogenide glass films for enhanced upconversion  

NASA Astrophysics Data System (ADS)

Gallium lanthanum oxysulfide (GLSO) is a promising host material for observing strong upconversion emission from trivalent rare-earth ions such as erbium (Er3+). Its attractive properties include high rare-earth solubility due to the lanthanum content of the glass former, a high refractive index (n = 2.2 at 550nm) for high radiative efficiency, and a low maximum phonon energy of approximately 425cm -1. Photonic crystals meanwhile can provide controlled light extraction, and may be capable of suppressing unwanted IR emission from lower lying metastable states. Here, we describe the fabrication of photonic crystals in annealed films of Er3+-doped GLSO deposited by RF sputtering. The most intense visible upconversion emission is observed in films annealed at 550°C, close to the bulk glass transition temperature. Hexagonal lattice photonic crystals are subsequently milled into the films using a focused ion beam (FIB). The milling parameters are optimized to produce the most vertical sidewall profile.

Pollard, M. E.; Knight, K. J.; Parker, G. J.; Hewak, D. W.; Charlton, M. D. B.

2012-02-01

95

Magnetic and Magneto-optic Properties of EuO Films Doped with Trivalent Rare-Earth Oxide  

Microsoft Academic Search

The ferromagnetic Curie temperature of EuO films has been increased by selective doping with trivalent rare-earth oxides. The electrical resistivity, which depends upon the temperature and has a broad peak at ≈100°K, decreases markedly to ≈10?1 ?·cm with doping. A typical ferromagnetic Curie temperature, determined from magneto-optic measurements in zero applied field, is ?135°K. Maximum longitudinal Faraday rotation occurs at

K. Y. Ahn; T. R. McGuire

1968-01-01

96

Fabrication and characterization of rare-earth metal-chelate-doped plastic film and fiber materials: Eu(3+)-chelate-doped PMMA  

NASA Astrophysics Data System (ADS)

High concentration rare-earth metal ion chelates, Europium 6,6.7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5,- octanedionate, (Eu-FOD) doped PMMA fiber and film were successfully prepared for the first time by casting solution method and gel spinning method. The optical and photoelectric characteristics of Eu(3+)-FOD doped PMMA film and fiber were investigated. Amplified spontaneous emission (ASE) from the Eu-FOD doped PMMA film and fiber was observed. The high concentration Eu-FOD-doped PMMA fiber and film sample exhibited lasing threshold as low as o. 15 mJ/ cm2 when pumped with a 355 nm pulsed laser beam.

Horinouchi, Suguru; Wada, M.; Ishihara, Koki; Eguchi, Masashi; Zhang, Gongjian; Ishikawa, T.; Watanabe, A.; Wang, Lili; Ogata, Naoya

2002-08-01

97

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

E-print Network

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.

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

2007-05-08

98

Long persistent alkali-earth silicate phosphors doped with Eu2+,Nd3+  

NASA Astrophysics Data System (ADS)

Phosphors of SrnMgSi2O5+n(1?n?2) singly doped with Eu2+ or doubly doped with Eu2+ and Nd3+ were prepared by using a solid state chemical reaction method. X-ray diffraction spectra revealed that the SrnMgSi2O5+n(1?n?2) compounds have the same crystal structure as Sr2MgSi2O7. The samples showed a strong blue emission at 470nm. Their excitation bands are from 250to450nm which were assigned to the 5d-4f transitions of Eu2+. Energy transfer between Eu2+ ions in inequivalent sites was found. Temperature dependence of photoluminescence was studied. A decrease of luminescence intensity and a blueshift of the emission spectra with increasing temperature were observed in both SrMgSi2O6:Eu2+ and Sr2MgSi2O7:Eu2+. Persistent afterglow was detected in the samples. The Eu2+ blue afterglow emission could be greatly enhanced by codoping trivalent rare earth ions, such as Nd3+. Thermoluminescence measurements revealed that doping with Nd3+ created a much large number of traps and hence enhanced the afterglow.

Jia, Dongdong; Jia, Weiyi; Jia, Yi

2007-01-01

99

Rare-earth doped solid-state phosphor with temperature-induced variable chromaticity  

NASA Astrophysics Data System (ADS)

A temperature induced variable chromaticity phosphor based upon a rare-earth multi-doped solid-state frequency upconverter is presented. The phosphors are composed of ytterbium-sensitized multiple doped(Tm, Er, Ho) lead-cadmium fluorogermanate glass samples excited by a laser source around 1064 nm. The temperature induced color variation exploits the heat enhanced effective absorption cross-section of the ytterbium sensitizer under multiphonon-assisted anti-Stokes excitation. The temperature enhancement of the energy-transfer mechanism between the sensitizer and the appropriate active light emitter ion allows the selective intensity control of the RGB emission wavelengths due to different upconversion excitation routes. The suitable combination of rare-earth active ions yielded the generation of variable chromaticity light with CIE-1931 coordinates changing from CIE-X=0.283;Y=0.288 at 20°C to CIE-X= 0.349;Y=0.412 at 190 °C, and CIE-X=0.285;Y=0.361 at 25°C to CIE-X=0.367;Y=0.434 at 180°C in Yb3+/Tm3+/Ho3+ and Yb3+/Tm3+/Er3+ multidoped samples, respectively. The viability of producing a low cost solid-state changeable visible color remote distributed temperature indicator in the 25°C - 300°C range is also discussed.

Gouveia-Neto, Artur S.; Bueno, Luciano A.; Nascimento, Raphael; Silva, Elias A.; Costa, Ernande B.

2009-02-01

100

Europium doped thiosilicate phosphors of the alkaline earth metals Mg, Ca, Sr and Ba: Structure and luminescence  

NASA Astrophysics Data System (ADS)

Divalent europium is notorious for the tunability of its emission, depending on the host material in which it is used as a dopant. In europium-doped alkaline earth thiosilicates, two distinct emission bands can be observed for the alkaline earth metals Mg, Ca and Sr while only a single band is found for barium thiosilicate. In this work, we first complete the data with europium-doped magnesiumthiosilicate. Then, the solid solution of calcium and magnesium thiosilicate is presented. To conclude, the presence of multiple emission peaks in some compounds is explained on a structural basis, by analysing the possibilities for preferential orientation of the europium d-orbitals.

Parmentier, Anthony B.; Smet, Philippe F.; Poelman, Dirk

2010-12-01

101

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

PubMed

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

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

2013-11-01

102

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

NASA Astrophysics Data System (ADS)

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.

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

2010-05-01

103

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

SciTech Connect

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.

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

104

Rare-earth doped GaN and InGaN quantum dots grown by plasma assisted MBE  

Microsoft Academic Search

We report on the MBE growth of GaN and InGaN quantum dots (QDs) doped with rare earth ions, namely Eu, Tm and Tb exhibiting red, blue and green luminescence, respectively. Intense photoluminescence\\/cathodoluminescence is observed, resulting from the spatial localization of rare earth ions in dots combined with the confinement properties of the carriers. White light emission has been produced by

Y. Hori; T. Andreev; X. Biquard; E. Monroy; D. Jalabert; Le Si Dang; M. Tanaka; O. Oda; B. Daudin

2005-01-01

105

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

E-print Network

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 ...

Byun, Hyunil

2006-01-01

106

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

NASA Astrophysics Data System (ADS)

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

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

1997-02-01

107

Spectroscopic studies of copper doped alkaline earth lead zinc phosphate glasses  

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

108

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

PubMed

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

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

2013-10-01

109

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

SciTech Connect

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.

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

110

Low temperature CO sensor based on cataluminescence from plasma-assisted catalytic oxidation on Ag doped alkaline-earth nanomaterials.  

PubMed

Based on cataluminescence from plasma-assisted catalytic oxidation, a low temperature CO sensor was fabricated. With Ag doped alkaline-earth catalyst as sensing element, air as discharge gas, carrier gas and oxidant supplier, significant cataluminescence was achieved at low temperature, demonstrating a potential low-consumption and portable sensor of CO. PMID:24519492

Han, Jiaying; Han, Feifei; Ouyang, Jin; He, Lixin; Zhang, Yantu; Na, Na

2014-03-21

111

Preparation and Luminescence Properties of Rare Earth Doped Nanostructured Zinc Oxide Thin Films by Sol Gel Technique  

Microsoft Academic Search

Zinc oxide is a semiconductor cosidered promising for optoelectronic and solar cell applications. The wide bandgap nature of the zinc oxide has been a limitation in producing devices. Doping has been considered as one of the ways to reduce the band gap. In the present studies rare earth ions in the form of terbium and erbium nitatres have been introduced

Madzlan Aziz; Sunati Otoi

2009-01-01

112

Analytic modeling of Brillouin gain in rare-earth doped fiber amplifiers with high-power single-frequency signals  

Microsoft Academic Search

The effect of temperature variation along a high power fiber amplifier on the SBS threshold is considered theoretically. We show that for an end-pumped rare-earth doped double-clad fiber the inhomogeneous distribution of temperature, which is caused by absorption of pump radiation, may result in total suppression of SBS even for output powers well above 200 W.

V. I. Kovalev; R. G. Harrison; J. Nilsson; Y. Jeong; V. Hernandes-Solis; J. K. Sahu

2005-01-01

113

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

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

114

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

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

115

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

NASA Astrophysics Data System (ADS)

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

Chandrasekharan, Sreerenjini

116

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

SciTech Connect

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}.

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

117

Rare earth doped optical fiber fabrication by standard and sol-gel derived granulated oxides  

NASA Astrophysics Data System (ADS)

We present our progress in the production of ytterbium (Yb) doped optical fibers fabricated by two variants of the granulated aluminophosphosilicate method. We show advantages and disadvantages of mixing rare earth and aluminophosphosilicate granulated oxides directly (variant 1) or by using the sol-gel method to produce doped granulate material (variant 2). For both methods we studied the effects of varying the dopant concentrations and of introducing iterative melting and milling procedures. In particular, the sol-gel based method eases the inclusion of P2O5 and thus, in combination with Al2O3, higher dopant concentration of Yb and Er are possible. Sintering the sol-gel material at high temperature eliminated bubbles in the core. We fabricated optical fibers that, piecewise, between individual strong scatterers, exhibited attenuation losses as low as 0.35dB/m. For our comparative study we determined volume percentage and distribution of chemical elements in the fabricated fiber glasses by the analytical technique of Energy-Dispersive X-ray, Electro Probe Microanalysis and the degree of crystallization by X-Ray Diffraction analysis. Furthermore we measured fluctuations of the refractive index profile and scattering losses of the fiber core.

Etissa, D.; Neff, M.; Pilz, S.; Ryser, M.; Romano, V.

2012-04-01

118

Potential rare earth free permanent magnet: interstitial boron doped FeCo  

NASA Astrophysics Data System (ADS)

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.

Khan, Imran; Hong, Jisang

2014-10-01

119

XPS and NEXAFS studies of rare-earth doped amorphous sol–gel films  

Microsoft Academic Search

Information about the structural environment of rare-earth (RE) ions in different host matrices is necessary in order to select a glass composition with optimized spectral properties for integrated optic devices, such as lasers or amplifiers. The present study is aimed at determining the influence of co-dopant elements (P and Al) on the structural environment around (RE) cations (Nd3+ and Er3+)

Rui M Almeida; H Cristina Vasconcelos; M Clara Gonçalves; Lu??s F Santos

1998-01-01

120

Synthesis and evaluation of rare-earth doped glasses and crystals for optical refrigeration  

NASA Astrophysics Data System (ADS)

This research focused on developing and characterizing rare-earth doped, solid-state materials for laser cooling. In particular, the work targeted the optimization of the lasercooling efficiency in Yb3+ and Tm3+ doped fluorides. The first instance of laser-induced cooling in a Tm3+-doped crystal, BaY2F8 was reported. Cooling by 3 degrees Kelvin below ambient temperature was obtained in a single-pass pump geometry at lambda = 1855 nm. Protocols were developed for materials synthesis and purification which can be applied to each component of ZBLANI:Yb 3+/Tm3+ (ZrF4 -- BaF2 -- LaF3 -- AlF3 -- NaF -- InF3: YbF3/TmF3) glass to enable a material with significantly reduced transition-metal impurities. A method for OH- impurity removal and ultra-drying of the metal fluorides was also improved upon. Several characterization tools were used to quantitatively and qualitatively verify purity, including inductively-coupled plasma mass spectrometry (ICP-MS). Here we found a more than 600-fold reduction in transition-metal impurities in a ZrCl2O solution. A non-contact spectroscopic technique for the measurement of laser-induced temperature changes in solids was developed. Two-band differential luminescence thermometry (TBDLT) achieved a sensitivity of ˜7 mK and enabled precise measurement of the zero-crossing temperature and net quantum efficiency. Several Yb3+-doped ZBLANI glasses fabricated from precursors of varying purity and by different processes were analyzed in detail by TBDLT. Laser-induced cooling was observed at room temperature for several of the materials. A net quantum efficiency of 97.39+/-0.01% at 238 K was found for the best ZBLANI:1%Yb 3+ laser-cooling sample produced from purified metal-fluoride precursors, and proved competitive with the best commercially procured material. The TBDLT technique enabled rapid and sensitive benchmarking of laser-cooling materials and provided critical feedback to the development and optimization of high-performance optical cryocooler materials. Also presented is an efficient and numerically stable method to calculate time-dependent, laser-induced temperature distributions in solids, including a detailed description of the computational procedure and its implementation. The model accurately predicted the zero-crossing temperature, the net quantum efficiency, and the functional shape of the transients, based on input parameters such as luminescence spectra, dopant concentration, pump properties, and several well-characterized material properties.

Patterson, Wendy

121

Integrated Thermal Response Tool for Earth Entry Vehicles  

NASA Technical Reports Server (NTRS)

A system is presented for multi-dimensional, fully-coupled thermal response modeling of hypersonic entry vehicles. The system consists of a two-dimensional implicit thermal response, pyrolysis and ablation program (TITAN), a commercial finite-element thermal and mechanical analysis code (MARC), and a high fidelity Navier-Stokes equation solver (GIANTS). The simulations performed by this integrated system include hypersonic flow-field, fluid and solid interaction, ablation, shape change, pyrolysis gas generation and flow, and thermal response of heatshield and structure. The thermal response of the ablating and charring heatshield material is simulated using TITAN, and that of the underlying structural is simulated using MARC. The ablating heatshield is treated as an outer boundary condition of the structure, and continuity conditions of temperature and heat flux are imposed at the interface between TITAN and MARC. Aerothermal environments with fluid and solid interaction are predicted by coupling TITAN and GIANTS through surface energy balance equations. With this integrated system, the aerothermal environments for an entry vehicle and the thermal response of both the heatshield and the structure can be obtained simultaneously. Representative computations for a proposed blunt body earth entry vehicle are presented and discussed in detail.

Chen, Y.-K.; Milos, F. S.; Partridge, Harry (Technical Monitor)

2001-01-01

122

An integrated view of data quality in Earth observation  

PubMed Central

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

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

2013-01-01

123

Transport properties of rare earth doped La{sub 2-x}Sr{sub x}CuO{sub 4}  

SciTech Connect

The authors present measurements of the resistivity, the thermopower, and the thermal conductivity of rare earth (RE) doped La{sub 2{minus}x}Sr{sub x}CuO{sub 4}. Pronounced anomalies occur at the low temperature structural phase transition showing that the electronic properties as well as the lattice dynamics depend strongly on small structural changes. The authors results indicate that a suppressed phonon heat transport is a characteristic feature of La{sub 2}CuO{sub 4} based superconductors. A possible relationship to the presence of stripe correlations of holes and spins in doped La{sub 2}CuO{sub 4} is discussed.

Buechner, B.; Lang, A.; Baberski, O.; Huecker, M. [Universitaet zu Koeln (Germany)] [and others

1996-11-01

124

Integrating spacecraft and aircraft in Earth Observation System architectures  

E-print Network

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. ...

Suarez, Brandon H

2011-01-01

125

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

Microsoft Academic Search

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

R. D. Clark

2005-01-01

126

Pulsed laser deposition of rare-earth-doped gallium lanthanum sulphide chalcogenide glass thin films  

NASA Astrophysics Data System (ADS)

Amorphous chalcogenide thin films are of high current interest for technological applications as optical storage media or waveguides for photonic integrated circuits. As part of a larger project including fs, ps and ns pulsed laser deposition regimes, Er- and Pr-doped GLS thin films were deposited by ns PLD, and their structural, chemical and optical properties were analyzed by optical and electronic microscopy, stylus profilometry, X-ray diffraction, Raman spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), energy-dispersive X-ray spectroscopy, variable-angle spectroscopic ellipsometry and optical transmission. Films deposited at moderate fluence (~4 J/cm2) in UV (266 nm) presented a good surface quality, while exhibiting acceptable composition uniformity and deviations from stoichiometry in line with the literature. Composition and optical properties dependences on the deposition conditions were investigated and discussed with respect to previous studies on similar systems.

Pompilian, O. G.; Dascalu, G.; Mihaila, I.; Gurlui, S.; Olivier, M.; Nemec, P.; Nazabal, V.; Cimpoesu, N.; Focsa, C.

2014-10-01

127

Generation of green, red and white light from rare-earth doped Ga 2O 3 nanoparticles  

NASA Astrophysics Data System (ADS)

We report the solvothermal synthesis of pure and rare-earth ions doped Ga 2O 3 nanoparticles for blue (Ga 2O 3), green (Tb 3+) and red (Eu 3+) emission. Bright white emission can be produced by tuning dopant ions. The CIE co-ordinate values of the white light are 0.32, 0.36, which are well within the white region of the chromaticity diagram. Steady state and time-resolved spectroscopic studies were performed to understand the mechanism. Analysis suggests that semiconducting Ga 2O 3 nanoparticles sensitize the rare-earth activator, which leads to an energy transfer system that produces a bright white light.

Sinha, Godhuli; Patra, Amitava

2009-04-01

128

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

E-print Network

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

Steckl, Andrew J.

129

Fluorescence enhancement in rare earth doped sol-gel glass by N , N dimethylformamide as a drying control chemical additive  

Microsoft Academic Search

Studies of terbium fluorescence intensity as a function of annealing temperature reveal the cause of increased fluorescence yields observed in rare earth doped sol-gel silicates prepared using N,N-dimethylformamide (DMF) as a drying control chemical additive (DCCA). While gels prepared with DMF actually have lower fluorescence yields than gels prepared without DMF at lower annealing temperatures, DMF gels can be annealed

A. P. Beyler; D. M. Boye; K. R. Hoffman; A. J. Silversmith

2011-01-01

130

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

SciTech Connect

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.

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

131

Status of broadband rare-earth doped fiber sources for fiber optic gyro applications  

NASA Astrophysics Data System (ADS)

Sources with broadband spectra are required for high-grade fiber optic gyroscopes (FOG). To date, the most widely used broadband FOG source is the superluminescent laser diode (SLD), which was developed by the semiconductor laser industry to meet this specific market. However, in spite of significant improvements, commercial SLDs still suffer from a few shortcomings. In response to these limitations, a second class of broadband sources has been under investigation over the last few years, which utilize a rare earth doped fiber as the active medium. Several types of broadband fiber sources have been demonstrated. They offer the advantages of high efficiencies, pumping with a laser diode (LD), high power into the FOG (tens of mW), and a mean wavelength stability with temperature at least one order of magnitude greater than for an SLD. Several university and industrial laboratories have now produced broadband fiber sources with properties far exceeding, on all counts, those of SLDs. The object of this paper is to review the properties of these sources, and their preliminary performance in FOG test beds.

Digonnet, Michel J. F.

1994-03-01

132

Engineering rare-earth-doped heavy metal oxide glasses for 2-5 ?m lasers  

NASA Astrophysics Data System (ADS)

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

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

2010-04-01

133

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

NASA Astrophysics Data System (ADS)

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.

Pokhrel, Madhab

134

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...

135

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

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

136

Integrated assessment of packaging architectures in earth observing programs  

E-print Network

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 ...

Selva Valero, Daniel

137

Room temperature hydrogen response kinetics of nano–micro-integrated doped tin oxide sensor  

Microsoft Academic Search

The nano–micro-integrated sensor has been fabricated by sol–gel depositing the nanocrystalline indium oxide (In2O3)-doped tin oxide (SnO2) thin film on microelectromechanical systems (MEMS) device having interdigitated electrode configurations with two different electrode spacing (10?m and 20?m) and two different number of fingers (8 and 20). The present nano–micro-integrated sensor exhibits high H2 sensitivity range (S=3–105) for the H2 concentration within

Satyajit Shukla; Peng Zhang; Hyoung J. Cho; Sudipta Seal; Lawrence Ludwig

2007-01-01

138

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

PubMed Central

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

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

139

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

PubMed Central

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

2013-01-01

140

Study of structure and magnetic properties of rare earth doped BiFeO3  

NASA Astrophysics Data System (ADS)

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.

Suresh, Pittala; Srinath, S.

2014-09-01

141

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

PubMed

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

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

2012-11-15

142

Preparation and Luminescence Properties of Rare Earth Doped Nanostructured Zinc Oxide Thin Films by Sol Gel Technique  

NASA Astrophysics Data System (ADS)

Zinc oxide is a semiconductor cosidered promising for optoelectronic and solar cell applications. The wide bandgap nature of the zinc oxide has been a limitation in producing devices. Doping has been considered as one of the ways to reduce the band gap. In the present studies rare earth ions in the form of terbium and erbium nitatres have been introduced in the zinc oxide structure by the sol gel technique. Homogeneous thin film of nanostructured oxide and the doped homologue of the size range 30 to 80 nm were produced as characterized by scanning electron microscopy. The luminescence properties were investigated and the doped samples showed enhanced results. The enhancement were characterized as the extra energy levels produced by the dopants allowing more transitions to the lower states to take place. The dominant transitions were attributed to the 5D4 to 7Fj (J = 6-3) for the terbium doped systems and (4F7/2) to the ground state 4I15/2) for the erbium systems.

Aziz, Madzlan; Otoi, Sunati

2009-06-01

143

Properties of Oxygen Deficient Thin Films of Hole doped Rare Earth Manganites: Correlation with the Cation Stoichiometry  

NASA Astrophysics Data System (ADS)

Alkaline-earth doped rare earth manganese oxides RE1-xAExMnO3 exhibit a wide array of electrical and magnetic properties depending on the cation composition stoichiometry. The composition x=0.33 is known to exhibit insulator-metal transition accompanied by a ferromagnetic transition and ``colossal magnetoresistance.'' The transition temperatures depend on the choice of rare earth and alkaline earth cations, the parameter governing this dependence being the average ionic size at the rare earth site (A-site). In thin films of these materials, the oxygen stoichiometry is also a variable which influences the electrical and magnetic properties through changes in the mixed valence state of Mn, i.e. the ratio of Mn^3+ to Mn^4+ ions. Based on our studies on several manganite systems, we will present results correlating the effects of oxygen deficiency with the cation stoichiometry at the A site. Properties of interest include structural parameters, electrical and magneto-transport and surface morphology.

Keshavarz, Camron; Sharma, Prakash; Goehringer, Tyler; Tanyi, E. Kevin; Hobbs, Erik; Watson, Michael; Yong, Grace; Schaefer, David; Kolagani, Rajeswari

2013-03-01

144

Nuclear-magnetic-resonance characterization of doped SiO2 films used in integrated circuits  

NASA Astrophysics Data System (ADS)

Phosphorus-doped silicon dioxide dielectric films, prepared by plasma-enhanced chemical-vapor deposition at low temperature (400 °C), play a critical role in the reliability of very large scale integration devices. The phosphorus in the phosphosilicate glass (PSG) neutralizes the effect of mobile ion species and improves the glass flow, resulting in better gap filling and improved planarization. To extract the maximum contribution from this and other doped films (boron and germanium doped) in advanced sub-0.5 ?m complimentary metal-oxide-semiconductor technologies, it is necessary to understand dopant incorporation and the effects of variation in the exposure to water, dopant concentration, and high-temperature annealing. An analysis of PSG by 1H, 29Si, and 31P solid-state nuclear magnetic resonance establishes the chemistry of the phosphorus dopant incorporation and the effect of moisture on the glass structures. Exposure to water results in a depolymerization of the PSG structures and a concurrent decrease in the crosslink density of the glass network. Similar concentrations of silanols are observed in both doped and undoped samples of SiO2. An increase in silanol concentration is found in P-doped glass after exposure to moisture in air. The level of exposure to water will determine the extent of structural changes in the dielectric film. Variations in this exposure can be expected to produce variability in the glass flow and other properties of the dielectric.

Schilling, Frederic C.; Steiner, Kurt G.; Obeng, Yaw S.

1995-07-01

145

Nuclear-magnetic-resonance characterization of doped SiO2 films used in integrated circuits  

NASA Astrophysics Data System (ADS)

Phosphorus-doped silicon dioxide dielectric films, prepared by plasma-enhanced chemical-vapor deposition at low temperature (400 °C), play a critical role in the reliability of very large scale integration devices. The phosphorus in the phosphosilicate glass (PSG) neutralizes the effect of mobile ion species and improves the glass flow, resulting in better gap filling and improved planarization. To extract the maximum contribution from this and other doped films (boron and germanium doped) in advanced sub-0.5 ?m complimentary metal-oxide-semiconductor technologies, it is necessary to understand dopant incorporation and the effects of variation in the exposure to water, dopant concentration, and high-temperature annealing. An analysis of PSG by 1H, 29Si, and 31P solid-state nuclear magnetic resonance establishes the chemistry of the phosphorus dopant incorporation and the effect of moisture on the glass structures. Exposure to water results in a depolymerization of the PSG structures and a concurrent decrease in the crosslink density of the glass network. Similar concentrations of silanols are observed in both doped and undoped samples of SiO2. An increase in silanol concentration is found in P-doped glass after exposure to moisture in air. The level of exposure to water will determine the extent of structural changes in the dielectric film. Variations in this exposure can be expected to produce variability in the glass flow and other properties of the dielectric.

Schilling, Frederic C.; Steiner, Kurt G.; Obeng, Yaw S.

1995-09-01

146

Studies on linear multistep algorithm for the orbital integration of artificial Earth satellites  

Microsoft Academic Search

The progress in the author's studies on linear multistep algorithm for the orbital integration of artificial Earth satellites are summarized. Three basic principles are introduced to determine the spurious roots of the eigen-polynomial. Five linear multistep integrators are recommended to use in practice, and they have obvious advantages over both symmetric and Cowell methods by means of their comparisons of

Jihong Xu

1999-01-01

147

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

NASA Astrophysics Data System (ADS)

Chalcogenide glasses and glass-ceramics present a high interest for the production of thermal imaging lenses transparent in the 3--5 microm and 8--12 microm windows. However, chalcogenide glasses are conventionally synthesized utilizing expensive and single use silica ampoules sealed under vacuum. The present work addresses the development of innovative synthesis methods for chalcogenide glasses that can present an alternative to the silica tube route. The first approach assessed by melting the raw starting elements in reusable silica containers appears inadequate for synthesis of glasses from the system Ge-Ga-Se. The second synthesis approach consists of the preparation of amorphous chalcogenide powders by ball milling of raw elements (mechanosynthesis) followed by consolidation of the as-prepared powders. Hot Uniaxial Pressing is suitable for sintering of powders with compositions stable against crystallization but uncontrolled crystallization occurs for the unstable compositions. In contrast, consolidation through Spark Plasma Sintering (SPS) allows production of bulk glasses with large dimensions in a short duration and at relatively low temperatures. Moreover, increased SPS treatment duration yields infrared transparent glass-ceramics with enhanced mechanical properties. This innovative synthesis method combining mechanosynthesis and SPS has been patented in the framework if this study. The controlled etching of 80GeSe2-20Ga2Se 3 glass-ceramics in acid solution yields nanoporous materials with enhanced surface area. The porous layer created on the surface of the glass-ceramic plays the role of anti-reflection coating and increases the optical transmission in the infrared range by 10%. These materials present potential for the production of sensors with increased sensitivity. The influence of indium and lead addition on the thermal and optical properties of the 80GeSe2-20Ga2Se3 glass is also assessed. Increased In or Pb contents tend to decrease the Tg and shift the optical band gap toward higher wavelengths. A systematic ceramization study emphasizes the difficulty of controlling the crystallization for glasses in the systems GeSe2-Ga2Se3-In2Se 3 and GeSe2-Ga2Se3-PbSe. No crystallization of the In2Se3 and PbSe crystalline phase was obtained. Finally, the possibility of producing rare-earth doped 80GeSe2 -20Ga2Se3 glass-ceramics transparent in the infrared region up to 16 microm is demonstrated. Enhanced photoluminescence intensity and reduced radiative lifetimes are observed with increased crystallinity in these materials.

Hubert, Mathieu

148

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

149

Optical Nanocomposite Planar Waveguides Doped with Rare-Earth and Noble Metal Elements  

Microsoft Academic Search

The present paper is focused on multilayer Er3+-doped silica-titania planar waveguides, co-doped with silver, which were prepared by spin-coating on silica glass, or buffered single crystal silicon substrates. The single layer thickness (~0.4 µm) and refractive index (~1.60–1.63) were measured by spectroscopic ellipsometry at 715 nm. The thickness of the waveguides (measured by mechanical profilometry) was ~1 µm and their

Rui M. Almeida; Ana C. Marques; Maurizio Ferrari

2003-01-01

150

Nuclear-magnetic-resonance characterization of doped SiO2 films used in integrated circuits  

Microsoft Academic Search

Phosphorus-doped silicon dioxide dielectric films, prepared by plasma-enhanced chemical-vapor deposition at low temperature (400 °C), play a critical role in the reliability of very large scale integration devices. The phosphorus in the phosphosilicate glass (PSG) neutralizes the effect of mobile ion species and improves the glass flow, resulting in better gap filling and improved planarization. To extract the maximum contribution

Frederic C. Schilling; Kurt G. Steiner; Yaw S. Obeng

1995-01-01

151

Luminescence properties of barium - gadolinium-titanate ceramics doped with rare-earth ions (Eu(3+) and Tb(3+) ).  

PubMed

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. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24616270

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

2014-11-01

152

The Digital Library for Earth System Education: A Community Integrator  

NASA Astrophysics Data System (ADS)

The rapid changes in the geoscience research environment have prompted educators to request support for their efforts to reform geoscience educational practices. DLESE, the Digital Library for Earth System Education, responds to this request by providing a single point of access to high-quality educational resources for teaching about the Earth as a system. DLESE is supported by the National Science Foundation and is an operational library used by tens of thousands of educators every month. DLESE resources include a variety of media formats, from text-based lesson plans to highly-sophisticated tools for interactive three-dimensional visualization of authentic scientific data. The DLESE community is particularly interested in partnering with scientific researchers to ensure that the tools of practicing scientists become widely available to geoscience educators. Two emerging large-scale scientific efforts, the GEON project and EarthScope, provide compelling illustrations of the potential of these partnerships. Both are cutting-edge, cross-disciplinary projects that use digital tools in a distributed environment to support scientific investigation. Both have also made a deep commitment to use these same tools to support geoscience education, and both are including DLESE as part of that commitment. Our interactive presentation will allow users to discover a variety of educational resources and communication services within the library. We will highlight those library resources and services that take particular advantage of the digital media to support new modes of learning and teaching. For example, annotation tools allow educators to add tips on the most effective way to use a specific resource. Data services will help educators find and use real-time data to illustrate geoscience phenomena. Multi-dimensional visualization tools allow students to interact with authentic student data in inquiry-based learning environment. DLESE will continue to actively collaborate with scientific research efforts to ensure that the practices and tools of the research community also support the needs of geoscience learners and educators.

Marlino, M. R.; Pandya, R. E.

2003-12-01

153

Role of charge transfer state and host matrix in Eu3+-doped alkali and earth alkali fluoro-aluminoborate glasses  

NASA Astrophysics Data System (ADS)

Judd-Ofelt parameters of Eu3+-doped alkali and earth alkali fluoro-aluminoborate glasses are determined from the fluorescence spectra. The dependence of these parameters on the compositional changes of the materials is discussed. The glass containing sulphate component shows the larger values of ? compared with the fluoro-aluminoborate glasses because of higher ?CT (Eu3+-F-) values. The difference of ionic radius and electronegativity between Na and Ca lead to higher ?2 parameter of CaF2-Al2O3-B2O3:Eu3+ glass. Persistent spectral hole burning has been observed in Eu3+ ions doped alkali-and earth alkali fluoro-aluminoborate glasses with the compositions of 16NaF·73B2O3·8Al2O3·3Eu2O3 and 16CaF2·73B2O3·8Al2O3·3Eu2O3, which have been prepared using conventional melting technique.

Thanh, N. T.; Quang, V. X.; Tuyen, V. P.; Tam, N. V.; Hayakawa, T.; Huy, B. T.

2012-06-01

154

Rare-earth-doped LiNbO3 and KTiOPO4 (KTP) for waveguide quantum memories  

NASA Astrophysics Data System (ADS)

Optical waveguides in rare-earth-doped crystals are one of the most promising systems for practical implementations of quantum memory. To further develop these systems, detailed understanding of these materials is required. We report experimental studies of the optical properties and decoherence for Tm3+:LiNbO3, Pr3+:LiNbO3, Er3+:LiNbO3 and Er3+:KTiOPO4 (KTP) bulk crystals for quantum memory applications and discuss potential differences between the properties of the bulk single crystals and optical waveguides. These systems include the rare-earth ions most commonly exploited in quantum memory studies incorporated into two of the most technologically significant waveguide host materials. Photon echo methods were used to study decoherence as a function of temperature, applied magnetic field strength, dopant concentration and excitation wavelength. Decoherence mechanisms were investigated and modelled to interpret the observed behaviour. Spectral hole burning was used to characterize Stark and Zeeman effects. Bulk crystal properties were compared and contrasted to the properties of doped waveguides.

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

2012-06-01

155

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

E-print Network

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...

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

2013-01-01

156

Magnetic and optical properties of rare earth doped Sn0.95RE0.05O2-? (RE =Gd, Dy, Er)  

NASA Astrophysics Data System (ADS)

The magnetic and optical properties of rare earth (Gd, Dy, and Er) ion doped SnO2 bulk and optical properties of thin films are investigated. The bulk samples were found to show an upturn in ac magnetic susceptibility at low temperatures TU and exhibited a paramagnetic moment at room temperature. The band gap of the bulk samples was found to be independent of the rare earth (RE) ions while for the thin films it varied from 3.48 eV to 3.58 eV. The observed low temperature upturn suggests an interesting magnetic property in SnO2 with RE doping.

Mohan Kant, K.; Chandrasekaran, K.; Ogale, S. B.; Venkatesan, T.; Sethupathi, K.; Rao, M. S. R.

2005-05-01

157

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

158

Low-threshold integrated microlaser emitting in the blue formed from thulium doped silica  

NASA Astrophysics Data System (ADS)

While there are several methods for creating a blue microlaser, most have very high lasing thresholds and are not integrated on a silicon substrate. The present work demonstrates a blue laser based on the upconversion of thulium in a doped silica sol-gel microtoroid resonant cavity integrated on a silicon wafer. The thulium is pumped at 1060nm, and emission occurs near 780nm and 450nm. The high intensity of the circulating optical field in the microcavity increases the photon interaction pathlength and interaction time with the thulium atoms, enabling sub-mW thresholds at both blue and near-IR lasing emissions.

Mehrabani, Simin; Armani, Andrea M.

2014-03-01

159

Enhancement of thermopower of TAGS-85 high-performance thermoelectric materials by doping with the rare earth Dy  

SciTech Connect

Enhancement of thermopower is achieved by doping the narrow-band semiconductor Ag{sub 6.52}Sb{sub 6.52}Ge{sub 36.96}Te{sub 50} (acronym TAGS-85), one of the best p-type thermoelectric materials, with 1 or 2% of the rare earth dysprosium (Dy). Evidence for the incorporation of Dy into the lattice is provided by X-ray diffraction and increased orientation-dependent local fields detected by {sup 125}Te NMR spectroscopy. Since Dy has a stable electronic configuration, the enhancement cannot be attributed to 4f-electron states formed near the Fermi level. It is likely that the enhancement is due to a small reduction in the carrier concentration, detected by {sup 125}Te NMR spectroscopy, but mostly due to energy filtering of the carriers by potential barriers formed in the lattice by Dy, which has large both atomic size and localized magnetic moment. The interplay between the thermopower, the electrical resistivity, and the thermal conductivity of TAGS-85 doped with Dy results in an enhancement of the power factor (PF) and the thermoelectric figure of merit (ZT) at 730 K, from PF = 28 ?W cm{sup ?1} K{sup ?2} and ZT ? 1.3 in TAGS-85 to PF = 35 ?W cm{sup ?1} K{sup ?2} and ZT ? 1.5 in TAGS-85 doped with 1 or 2% Dy for Ge. This makes TAGS-85 doped with Dy a promising material for thermoelectric power generation.

Levin, Evgenii; Budko, Serfuei; Schmidt-Rohr, Klaus

2012-04-10

160

Earth  

NASA Technical Reports Server (NTRS)

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.

Carr, M. H.

1984-01-01

161

Experimental demonstration of efficient and selective population transfer and qubit distillation in a rare-earth-metal-ion-doped crystal  

SciTech Connect

In optically controlled quantum computers it may be favorable to address different qubits using light with different frequencies, since the optical diffraction does not then limit the distance between qubits. Using qubits that are close to each other enables qubit-qubit interactions and gate operations that are strong and fast in comparison to qubit-environment interactions and decoherence rates. However, as qubits are addressed in frequency space, great care has to be taken when designing the laser pulses, so that they perform the desired operation on one qubit, without affecting other qubits. Complex hyperbolic secant pulses have theoretically been shown to be excellent for such frequency-addressed quantum computing [I. Roos and K. Molmer, Phys. Rev. A 69, 022321 (2004)] - e.g., for use in quantum computers based on optical interactions in rare-earth-metal-ion-doped crystals. The optical transition lines of the rare-earth-metal-ions are inhomogeneously broadened and therefore the frequency of the excitation pulses can be used to selectively address qubit ions that are spatially separated by a distance much less than a wavelength. Here, frequency-selective transfer of qubit ions between qubit states using complex hyperbolic secant pulses is experimentally demonstrated. Transfer efficiencies better than 90% were obtained. Using the complex hyperbolic secant pulses it was also possible to create two groups of ions, absorbing at specific frequencies, where 85% of the ions at one of the frequencies was shifted out of resonance with the field when ions in the other frequency group were excited. This procedure of selecting interacting ions, called qubit distillation, was carried out in preparation for two-qubit gate operations in the rare-earth-metal-ion-doped crystals. The techniques for frequency-selective state-to-state transfer developed here may be also useful also for other quantum optics and quantum information experiments in these long-coherence-time solid-state systems.

Rippe, Lars; Nilsson, Mattias; Kroell, Stefan; Klieber, Robert; Suter, Dieter [Department of Physics, Lund Institute of Technology, P.O. Box 118, SE-22100 Lund (Sweden); Fachbereich Physik, Universitaet Dortmund, DE-44221 Dortmund (Germany)

2005-06-15

162

A soil moisture monitoring sensorweb demonstration in the context of integrated Earth sensing  

NASA Astrophysics Data System (ADS)

This paper describes work towards building an integrated Earth sensing capability, in particular the demonstration of a prototype in-situ sensorweb in autonomous remote operation in the context of soil moisture monitoring. A five-node prototype sensorweb was deployed and tested at Bratt's Lake Station in Saskatchewan. The sensorweb operated autonomously and standard meterological parameters and soil moisture measurements were accessed remotely via satellite from the Integrated Earth Sensing Workstation (IESW) at the Canada Centre for Remote Sensing in Ottawa. The paper reports on the prototype sensorweb deployment in general and on soil moisture measurements in particular.

Teillet, Philippe M.; Gauthier, Robert P.; Fedosejevs, Gunar; Maloley, Matthew; Chichagov, Alexander; Ainsley, Gino

2003-11-01

163

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

164

Integrated planning and scheduling for Earth science data processing  

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

165

Rare-Earth Doped LaF? Nanocrystals for Upconversion Fluorescence  

E-print Network

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, ...

Yi, Guang-Shun

166

Low-temperature specific heat of rare-earth-doped silicate glasses D. A. van de Straat, J. Baak, and H. B. Brom  

E-print Network

Low-temperature specific heat of rare-earth-doped silicate glasses D. A. van de Straat, J. Baak-order terms. The existence of a quasilinear contribution to the low- temperature specific heat of glasses1 work we show that the low- temperature specific heat depends on the composition of the silicate glass

Schmidt, Thomas

167

Rare earth doped silicate-oxyfluoride glass ceramics incorporating LaF3 nano-crystals for UV-LED color conversion  

NASA Astrophysics Data System (ADS)

Rare earth doped oxyfluoride glass ceramics with LaF3 nano-crystals formed inside were fabricated for color converter of UV-LED. Among various rare earth ions, Dy3+ and Eu3+ showed practically utilizable visible emissions under UV-LED excitation of 365 nm. The visible emission has been improved by the formation of LaF3 brought by heat treatment. X-ray diffraction and transmission electron microscopy along with its energy dispersive spectra confirmed the formation of LaF3 nano-crystals. Compositional dependence and the effects of heat treatment conditions on the visible emissions have been investigated. The CIE chromaticity coordinates of the glasses were also examined for Dy3+ singly doped and co-doped samples. The effect of LaF3 nano-crystals and co-dopants on the visible emission properties of Dy3+ was discussed.

Bae, Suk-Rok; Choi, Yong Gyu; Im, Won Bin; Lee, Ki Seok; Chung, Woon Jin

2013-09-01

168

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

Microsoft Academic Search

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

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

2012-01-01

169

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

Microsoft Academic Search

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

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

2010-01-01

170

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

SciTech Connect

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.

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

171

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

172

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

173

Room temperature ferromagnetism with large magnetic moment at low field in rare-earth-doped BiFeO? thin films.  

PubMed

Thin films of rare earth (RE)-doped BiFeO3 (where RE=Sm, Ho, Pr and Nd) were grown on LaAlO3 substrates by using the pulsed laser deposition technique. All the films show a single phase of rhombohedral structure with space group R3c. The saturated magnetization in the Ho- and Sm-doped films is much larger than the values reported in the literature, and is observed at quite a low field of 0.2 T. For Ho and Sm doping, the magnetization increases as the film becomes thinner, suggesting that the observed magnetism is mostly due to a surface effect. In the case of Nd doping, even though the thin film has a large magnetic moment, the mechanism seems to be different. PMID:23615045

Kim, Tae-Young; Hong, Nguyen Hoa; Sugawara, T; Raghavender, A T; Kurisu, M

2013-05-22

174

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

NASA Astrophysics Data System (ADS)

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

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

2007-04-01

175

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.

176

Up-conversion in rare earth-doped silica hollow spheres  

NASA Astrophysics Data System (ADS)

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.

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

2012-06-01

177

Laser cooling with rare-earth doped direct band gap semiconductors  

NASA Astrophysics Data System (ADS)

We present a theoretical scheme for laser cooling with ytterbium doped indium phosphide (Yb3+:InP). Yb3+:InP is a rareearth doped direct band-gap semiconductor. The cooling process in our system is based on thermal quenching of excited ytterbium ions. The mechanism of cooling in our system consists of laser excitation of ytterbium ions in the long wavelength tail of the Yb3+absorption spectrum followed by thermal quenching of excited ions accompanied by phonon absorption providing cooling. The band-to-band radiative recombination completing the cooling cycle removes energy from the system. This new approach to laser cooling of solids permits an increase in the efficiency of the cooling cycle approximately by the order, to accelerate the cooling process considerably, and allows cooling with pump wavelengths shorter than the mean fluorescence wavelength.

Nemova, Galina; Kashyap, Raman

2013-02-01

178

High-power wavelength-tunable cladding-pumped rare-earth-doped silica fiber lasers  

Microsoft Academic Search

We describe the design and performance of cladding-pumped silica fiber lasers with high continuous-wave output powers and broad wavelength tunability in the 1, 1.5, and 2 ?m spectral ranges. An ytterbium-doped fiber laser was tuned via wavelength dependent feedback provided by an external cavity containing a diffraction grating from 1027 to 1105 nm at multi-watt power levels. Similarly, high output

J. Nilsson; W. A. Clarkson; R. Selvas; J. K. Sahu; P. W. Turner; S.-U. Alam; A. B. Grudinin

2004-01-01

179

Spectroluminescence properties of potassium-aluminosilicophosphate glasses doped with rare-earth ions  

NASA Astrophysics Data System (ADS)

This paper discusses the results of a study of the spectroluminescence properties of potassium-aluminosilicophosphate glasses (PASPGs) doped with ions of the 4f elements. The matrix composition and the dopant concentration in the synthesized glasses are described. The general response of the absorption and luminescence spectra of trivalent Pr, Nd, Sm, and Eu ions in PASPGs are presented for the spectral regions in which the lasing transitions of the corresponding ions are located.

Batyaev, I. M.; Tinus, A. M.

2004-12-01

180

Controllable optical bistability and multistability in a rare-earth-ion-doped optical fiber  

NASA Astrophysics Data System (ADS)

We investigated the optical bistability and multistability in an Er3+-doped ZrF4-BaF2-LaF3-AlF3-NaF optical fiber inside an optical ring cavity. It is found that the optical bistability and multistability can be easily controlled via adjusting properly the parameters of the corresponding system. Our scheme may provide some new possibilities for technological applications in optoelectronics and optical-fiber communication.

Wang, Zhiping; Yu, Benli; Zhen, Shenglai; Wu, Xuqiang; Zhu, Jun; Cao, Zhigang

2012-03-01

181

High refractive index without absorption in a rare-earth-ion-doped optical fiber  

NASA Astrophysics Data System (ADS)

We demonstrate a new scheme for realizing the high refractive index with zero absorption in an Er3+-doped ZrF4-BaF2-LaF3-AlF3-NaF optical fiber. It is found that the refraction index of the probe laser can easily be controlled via adjusting properly the parameters of the corresponding system. Our scheme may provide some new possibilities for technological applications in optical-fiber communication.

Wang, Zhiping; Yu, Benli

2012-11-01

182

X-ray absorption spectroscopy and photoluminescence study of rare earth ions doped strontium sulphide phosphors  

NASA Astrophysics Data System (ADS)

We present here the electronic structure and photoluminescence properties of Sm (0.1-1.0 mol%) doped SrS phosphors. The doping in SrS was probed by near-edge X-ray absorption fine structure (NEXAFS) at M5,4-edges of Sm in total electron yield mode. The simulated absorption edges using atomic multiplet calculations were correlated with experimental results, which clearly reveal the presence of trivalent state of Sm in SrS matrix. However, for Sm (1 mol%), very minor traces of Sm2+ were also observed, which have been explained by comparing the NEXAFS spectra in total electron and florescence yield mode. The PL emission of SrS:Sm comprises of three sharp bands at 567, 602 and 650 nm owing to the well-known intra 4f transitions from 4G5/2 to 6HJ (J = 5/2, 7/2, 9/2) levels of Sm3+ ions in SrS host. The effect of Ce co-doping on SrS:Sm phosphors was also investigated, which exhibits characteristic PL emission of independent ions at their respective excitation wavelengths. However, at an excitation wavelength of 393 nm, SrS:Ce,Sm exhibits the simultaneous characteristic PL emission of both ions spanning into blue-green-red region. The CIE chromaticity coordinates also clearly show the influence of excitation wavelengths on the emission colour of SrS:Ce,Sm.

Vij, Ankush; Gautam, Sanjeev; Kumar, Vinay; Brajpuriya, R.; Kumar, Ravi; Singh, Nafa; Chae, Keun Hwa

2013-01-01

183

Research priorities in land use and land-cover change for the Earth system and integrated assessment modelling  

E-print Network

). Copyright ? 2010 Royal Meteorological Society and Crown Copyright. KEY WORDS land use; land cover; Earth system models; integrated assessment models; research priorities Received 12 January 2009; Revised 9 March 2010; Accepted 14 March 2010 1. Introduction 1... biogeophysical, socio- economic and human decision-making perspectives. The Earth System Modeling (ESM) and the Integrated Assessment Modeling (IAM) communities play an impor- tant role in understanding and quantifying Earth system analysis and, specifically...

Hibbard, Kathy; Janetos, Anthony; van Vuuren, Detlef P.; Pongtatz, Julia; Rose, Steven K.; Betts, Richard; Herold, Martin; Feddema, Johannes J.

2010-01-01

184

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

USGS Publications Warehouse

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

Bedrosian, P. A.

2007-01-01

185

Rare-Earth doped particles as dual-modality contrast agent for minimally-invasive luminescence and dual-wavelength photoacoustic imaging.  

PubMed

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

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

2014-01-01

186

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

187

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

PubMed Central

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

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

2014-01-01

188

Earth  

NSDL National Science Digital Library

With three levels to choose from on each page - beginner, intermediate or advanced - this site provides information on our plant Earth. There is a section about water on earth and its many different varities, like freshwater, groundwater, and frozen water. There is information about the chemical make-up of water and many images showing the different water anvironments. There is a section about life in water, such as animals, plants, and plankton.

2008-10-03

189

Fabrication of high concentration rare-earth-doped silica-based waveguide by MCVD method  

Microsoft Academic Search

Reports a technique of fabricating a buried channel silica-based optical waveguide containing the largest rare-earth concentration ever reported, i.e., 3 wt% in Nd2O3. Instead of the flame hydrolysis technique, these waveguides are manufactured by the standard MCVD method originally designed for fiber preform fabrication

B. Wu; P. L. Chu

1995-01-01

190

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

NASA Astrophysics Data System (ADS)

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

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

2007-08-01

191

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)

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.

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

2014-11-01

192

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

NASA Astrophysics Data System (ADS)

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.

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

2005-05-01

193

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

PubMed

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

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

2011-08-15

194

Simultaneous multidopant investigation of rare-earth-doped optical fibers by an ion microprobe.  

PubMed

The relative distribution of five elements present in the core area of several optical fiber samples has been obtained by utilizing nanoscale-secondary ion mass spectrometry. A strong correlation between the rare-earth (RE) ion and aluminum was observed, consistent with aluminum's improving the solubility of the RE ion. The central dip in distribution was less severe than that observed for germanium, characteristic of the collapse process during fabrication of the fiber preform. PMID:17072389

Sidiroglou, Fotios; Huntington, Shane T; Roberts, Ann; Stern, Richard; Fletcher, Ian R; Baxter, Greg W

2006-11-15

195

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.

196

Integral equation approach to investigate some problems within the Earth-Ionosphere waveguide  

NASA Astrophysics Data System (ADS)

WKB method has been applied to solve some integral equations arising out of wave-particle interaction within the upper atmosphere. Problem of ELF propagation through the Earth-Ionosphere waveguide has been investigated taking into account the inhomogeneities due to asymmetry of the day and night time ionosphere and variations of conductivity of the ionosphere. The results of numerical solutions are graphically presented through appropriate data and compared with previous results.

Sundar De, Syam; Paul, Suman; De, Dipanjan; Chattopadhyay, Subrata

2012-07-01

197

First-principles study of the magnetic properties of nitrogen-doped alkaline earth metal oxides  

NASA Astrophysics Data System (ADS)

We present a first-principles study of the magnetic properties of N-doped MgO, CaO and SrO, which have been proposed to constitute a new class of dilute magnetic semiconductors (DMSs) with no magnetic elements. In this study, it was found that under a homogeneously distributed condition, Curie temperatures could reach room temperature at sufficient N concentrations in the range of 20-30 at.%; however, an inhomogeneous N distribution in these DMSs is the favored configuration, which indicates that spinodal decomposition leads to a room-temperature blocking temperature at smaller N concentrations than those estimated for room-temperature ferromagnetism in the homogeneous distribution condition.

Seike, Masayoshi; An Dinh, Van; Sato, Kazunori; Katayama Yoshida, Hiroshi

2012-08-01

198

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

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

199

Luminescence properties of Sm3+-doped alkaline earth ortho-stannates  

NASA Astrophysics Data System (ADS)

A series of Sm3+ doped M2SnO4 (M = Ca, Sr and Ba) samples were prepared by a conventional high temperature solid-state reaction route. All samples were characterized by powder X-ray diffraction (XRD) analysis, photoluminescence (PL), photoluminescence thermal quenching (TQ) and fluorescence lifetime (FL) measurements. The morphology of synthesized phosphor powders was examined by scanning electron microscopy (SEM). Moreover, luminous efficacies (LE) and color points of the CIE 1931 color space diagram were calculated and discussed. Synthesized powders showed bright orange-red emission under UV excitation. Based on the results obtained we demonstrate that Sm3+ ions occupy Ca and Sr sites in the Ca2SnO4 and Sr2SnO4 ortho-stannate structures, respectively. In contrast, Sm3+ substitutes Sn in the barium ortho-stannate Ba2SnO4 structure.

Stanulis, Andrius; Katelnikovas, Art?ras; Enseling, David; Dutczak, Danuta; Šakirzanovas, Simas; Bael, Marlies Van; Hardy, An; Kareiva, Aivaras; Jüstel, Thomas

2014-05-01

200

Storage of images in atomic coherences in a rare-earth-ion-doped solid  

SciTech Connect

We report on storage of images in atomic coherences driven by electromagnetically induced transparency in a doped solid. We demonstrate image storage times up to the regime of milliseconds (i.e., more than two orders of magnitude larger than in gaseous media). Our data also reveal an improvement in the spatial resolution of the retrieved images by a factor of 40. The long storage times become possible by applying additional radio frequency pulse sequences to drive rephasing of the atomic coherences. Moreover, the perturbing effect of atomic diffusion (which significantly limits image storage times in gases) is absent in the solid. In addition, we monitored pronounced oscillations in the intensity of the retrieved image versus the storage time. These oscillations are due to the beating of dark-state polaritons. All of these results demonstrate the superior properties of coherently driven optical data storage in solids.

Heinze, G.; Rudolf, A.; Beil, F.; Halfmann, T. [Institut fuer Angewandte Physik, Technische Universitaet Darmstadt, Hochschulstrasse 6, D-64289 Darmstadt (Germany)

2010-01-15

201

Narrow inhomogeneous and homogeneous optical linewidths in a rare earth doped transparent ceramic  

NASA Astrophysics Data System (ADS)

Inhomogeneous and homogeneous linewidth are reported in a Eu3+ doped transparent Y2O3 ceramic for the 7F0-5D0 transition, using high-resolution coherent spectroscopy. The 8.7-GHz inhomogeneous linewidth is close to that of single crystals, as is the 59-kHz homogeneous linewidth at 3 K (T2 = 5.4 ?s). The homogeneous linewidth exhibits a temperature dependence that is typical of a crystalline environment, and additional dephasing observed in the ceramic is attributed to magnetic impurities or defects introduced during the synthesis process. The absence of Eu3+segregation at the grain boundaries, evidenced through confocal microfluorescence, further indicates that the majority of Eu3+ions in the ceramic experience an environment comparable to a single crystal. The obtained results suggest that ceramic materials can be competitive with single crystals for applications in quantum information and spectral hole burning devices, beyond their current applications in lasers and scintillators.

Ferrier, A.; Thiel, C. W.; Tumino, B.; Ramirez, M. O.; Bausá, L. E.; Cone, R. L.; Ikesue, A.; Goldner, Ph.

2013-01-01

202

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

SciTech Connect

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.

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

203

Properties of rare earth doped thin film dielectric layers for upconversion laser waveguides  

NASA Astrophysics Data System (ADS)

Thin films of erbium doped tantalum pentoxide were prepared on unheated <100> orientated silicon substrates with a thermally grown 2 ?m thick SiO2 layer using reactive sputtering in an oxygen rich environment for upconversion laser experiments. Tantalum and Erbium metal targets were co-sputtered using an ion beam assisted reactive process to produce the high quality amorphous thin film layers. The Erbium dopant concentration was adjusted by varying the relative deposition rate. Slab waveguide loss before high temperature annealing was measured to be 0.8 dB/cm at 633 nm which reduced to 0.5 dB/cm after annealing at 500 °C. Micron scale waveguides were etched into the deposited thin film slab waveguides using photolithography and reactive ion etching. Finally a silicon dioxide buffer layer was deposited on top of the ridge waveguides to help constrict the laser mode and to add a protective layer. 2 cm long waveguide samples were cleaved and polished to achieve good optical quality end facets for laser experiments. Upconversion efficiency and laser gain measurements were performed on the final waveguides. Waveguide losses of 6.35 dB/cm were measured for the final ridge waveguides and a coupling efficiency of 48 % was obtained. A positive net gain of 0.25 dB was measured for upconversion to 551 nm using a pump probe optical setup.

Pearce, S. J.; Charlton, M. D. B.; Parker, G. J.; Wilkinson, J. S.

2011-02-01

204

Calcination-free micropatterning of rare-earth-ion-doped nanoparticle films on wettability-patterned surfaces of plastic sheets.  

PubMed

We demonstrate a patterning technique of rare-earth-ion-doped (RE) nanoparticle films directly on wettability-patterned surfaces fabricated on plastic sheets in one step. Self-assembled monolayers consisting of silane-coupling agent with hydrophobic groups were fabricated on plastic sheets. UV-ozone treatments were performed through a metal mask to selectively remove the self-assembled monolayers in a patterned manner, resulting in the formation of wettability-patterned surfaces on plastic sheets. Using a water dispersion of Er(3+) and Yb(3+)-codoped Y2O3 nanoparticles at a diameter of 100 nm, RE-nanoparticle films were fabricated on the wettability-patterned surfaces by a dip-coating technique. By adjusting the concentration of RE-nanoparticle dispersion, withdrawal speed, and withdrawal angle, amount of RE-nanoparticles, we were able to control the structures of the RE-nanoparticle films. Fluorescence microscope observations demonstrate that visible upconversion luminescence and near-infrared fluorescence were emitted from the RE-nanoparticle films on the wettability-patterned surfaces. This technique allows for the fabrication of flexible emitting devices with long-operating life time with minimized material consumption and few fabrication steps, and for the application to sensors, emitting devices, and displays in electronics, photonics, and bionics in the future. PMID:24655829

Watanabe, Satoshi; Hamada, Yudai; Hyodo, Hiroshi; Soga, Kohei; Matsumoto, Mutsuyoshi

2014-05-15

205

Systematic investigation of rare-earth doped BiFeO3 thin films using composition spreads  

NASA Astrophysics Data System (ADS)

(1) Department of Materials Science and Engineering, University of Maryland, USA (2) University of New South Wales, AU (3) Center for Superconductivity Research, University of Maryland, We have systematically investigated compositionally varied rare-earth (RE) doped BiFeO3 thin films using the combinatorial approach. Epitaxially grown (Bi1-xREx)FeO3 composition spread thin films were fabricated by laser molecular beam epitaxy on SrTiO3 (001) substrates with an SrRuO3 buffer layer. Transmission electron microscopy of the films showed that homogeneous epitaxial films were obtained throughput the composition range. Structural properties of (Bi1-xREx)FeO3 was mapped using scanning x-ray diffraction, and structural transitions were observed at various compositions. In some compositions, substantial enhancement in ferroelectric properties was observed at the structural transition: increase in the dielectric constant, increase in the piezoelectric response, and decrease in the coercive field were observed, while high polarization is maintained. Detailed dependence of various properties on composition variation will be discussed. Work supported by NSF DMR 0094265, DMR 0231291, MRSEC DMR-00-0520471 and the W. M. Keck Foundation.

Fujino, S.; Nagarajan, V.; Murakami, M.; Lim, S.-H.; Vartharajan, A.; Salamanca-Riba, L.; Wuttig, M.; Takeuchi, I.

2007-03-01

206

White emission phosphors based on Dy3+-doped into anhydrous rare-earth benzenetricarboxylate complexes  

NASA Astrophysics Data System (ADS)

White light emitting rare earth anhydrous complexes RE(TMA):Dy3+ (RE3+ = Y3+ and Lu3+) containing the trimesic acid ligands (TMA) were synthesized and characterized by elemental analysis, X-ray diffraction patterns, thermogravimetric analysis and infrared spectroscopy. The crystallinity and thermostability of these luminescent materials were determined. Since the first excited triplet state (T1: 24,000 cm-1) of TMA ligand is located at higher energy than the main emitting 4F9/2 level (21,000 cm-1) of the Dy3+ ion, TMA can act as efficient luminescent sensitizer in the intramolecular energy transfer of RE(TMA):Dy3+ material. The near-white emission colour originated from the intraconfigurational transitions of Dy3+ ion 4F9/2?6HJ is discussed.

Silva, Ivan G. N.; Kai, Jiang; Felinto, Maria C. F. C.; Brito, Hermi F.

2013-03-01

207

Composition dependence of the magnetic properties of strontium hexaferrite doped with rare earth ions  

NASA Astrophysics Data System (ADS)

Rare earth substituted ferrite Sr1−xRExFe12O19 (where RE = La, Gd and Dy, x = 0.0, 0.10, 0.20 and 0.30), have been prepared by employing the ceramic technique and subsequent heat treatment. The magnetic properties of the calcined samples were characterized with a Vibrating Sample Magnetometer (VSM). The samples were sintered at 1150°C for 8 hours. The samples were characterized for magnetic properties such as specific saturation magnetization MS, specific remanence magnetization Mr, and coercivity Hc as well as microstructure. It has been observed that all these parameters depend on the composition and heat treatment of the prepared samples. The coercively Hc exhibits an increase as the RE content increases in Sr1−xRExFe12O19 ferrite. With increasing RE content the MS and Mr decrease due to dissolution of RE ion into hexaferrite lattice.

Singh, Taminder; Batra, M. S.; Singh, Iqbal; Katoch, Arun

2014-09-01

208

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

NASA Technical Reports Server (NTRS)

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.

Lousma, Jack R.

1992-01-01

209

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

PubMed

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

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

2013-11-01

210

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

NASA Astrophysics Data System (ADS)

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.

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

211

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

NASA Astrophysics Data System (ADS)

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.).

Knowles, David S.

212

Theoretical Study on Interactions between Oxygen Vacancy and Doped Rare-Earth Elements in Barium Titanate  

NASA Astrophysics Data System (ADS)

We performed first-principles theoretical calculations to examine the interactions between oxygen vacancy (VO) and rare-earth (RE) elements in barium titanate (BaTiO3), in order to clarify the mechanism of VO trapping by RE dopants, which affects the insulating reliability of BaTiO3-based multilayer ceramic capacitors (MLCC). It was found that VO is stabilized at the first and second nearest O sites of RE at Ba site (REBa), and at the second nearest O site of RE at Ti site (RETi). The structural relaxations on bond lengths of REBa-O and RETi-O in BaTiO3, which are brought about by the existence of VO at the above sites, decrease the total energy, and thus VO is stabilized. Furthermore, we revealed that the stability of VO increases with decreasing solution stability of RE dopants in BaTiO3. Accordingly, we concluded that RE dopants with higher solution energy in BaTiO3 efficiently trap VO, and thus the insulation reliability of MLCC is improved.

Honda, Atsushi; Higai, Shin'ichi; Motoyoshi, Yasuhiro; Wada, Nobuyuki; Takagi, Hiroshi

2011-09-01

213

Excitation and luminescence of rare earth-doped lead phosphate glasses  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

214

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

NASA Astrophysics Data System (ADS)

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

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

2004-12-01

215

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

NASA Astrophysics Data System (ADS)

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.

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

216

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

NASA Astrophysics Data System (ADS)

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.

Ceballos, Decio C.

1993-10-01

217

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

PubMed

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

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

2013-08-21

218

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

NASA Technical Reports Server (NTRS)

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.

Lousma, Jack R.

1992-01-01

219

The surface temperatures of Earth: steps towards integrated understanding of variability and change  

NASA Astrophysics Data System (ADS)

Surface temperature is a key aspect of weather and climate, but the term may refer to different quantities that play interconnected roles and are observed by different means. In a community-based activity in June 2012, the EarthTemp Network brought together 55 researchers from five continents to improve the interaction between scientific communities who focus on surface temperature in particular domains, to exploit the strengths of different observing systems and to better meet the needs of different communities. The workshop identified key needs for progress towards meeting scientific and societal requirements for surface temperature understanding and information, which are presented in this community paper. A "whole-Earth" perspective is required with more integrated, collaborative approaches to observing and understanding Earth's various surface temperatures. It is necessary to build understanding of the relationships between different surface temperatures, where presently inadequate, and undertake large-scale systematic intercomparisons. Datasets need to be easier to obtain and exploit for a wide constituency of users, with the differences and complementarities communicated in readily understood terms, and realistic and consistent uncertainty information provided. Steps were also recommended to curate and make available data that are presently inaccessible, develop new observing systems and build capacities to accelerate progress in the accuracy and usability of surface temperature datasets.

Merchant, C. J.; Matthiesen, S.; Rayner, N. A.; Remedios, J. J.; Jones, P. D.; Olesen, F.; Trewin, B.; Thorne, P. W.; Auchmann, R.; Corlett, G. K.; Guillevic, P. C.; Hulley, G. C.

2013-12-01

220

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

221

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

NASA Technical Reports Server (NTRS)

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

Stepinski, T. F.; Coradetti, S.

2004-01-01

222

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

223

The WADA Proficiency Testing Program as an integral part of the fight against doping in sport  

Microsoft Academic Search

This article provides a brief perspective of the World Anti-Doping Agency (WADA) in the context of the fight against doping\\u000a in sport and of the WADA Proficiency Testing Program as an essential element of the World Anti-Doping Program. The WADA Proficiency\\u000a Testing Program exists within the framework of the WADA-accredited laboratories and is aimed at improving the effectiveness\\u000a of the

Victoria Ivanova; Thierry Boghosian; Olivier Rabin

2007-01-01

224

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

NASA Astrophysics Data System (ADS)

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?"

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

2006-12-01

225

Integrating Authentic Earth Science Data in Online Visualization Tools and Social Media Networking to Promote Earth Science Education  

NASA Astrophysics Data System (ADS)

The Goddard Space Flight Center (GSFC) is one of the largest Earth Science research-based institutions in the nation. Along with the research comes a dedicated group of people who are tasked with developing Earth science research-based education and public outreach materials to reach the broadest possible range of audiences. The GSFC Earth science education community makes use of a wide variety of platforms in order to reach their goals of communicating science. These platforms include using social media networking such as Twitter and Facebook, as well as geo-spatial tools such as MY NASA DATA, NASA World Wind, NEO, and Google Earth. Using a wide variety of platforms serves the dual purposes of promoting NASA Earth Science research and making authentic data available to educational communities that otherwise might not otherwise be granted access. Making data available to education communities promotes scientific literacy through the investigation of scientific phenomena using the same data that is used by the scientific community. Data from several NASA missions will be used to demonstrate the ways in which Earth science data are made available for the education community.

Carter, B. L.; Campbell, B.; Chambers, L.; Davis, A.; Riebeek, H.; Ward, K.

2008-12-01

226

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

NASA Astrophysics Data System (ADS)

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+).

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

2014-11-01

227

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

PubMed

Robust, long-lived optical quantum memories are important components of many quantum information and communication protocols. We demonstrate coherent generation, storage, and retrieval of excitations on a long-lived spin transition via spontaneous Raman scattering in a rare-earth ion-doped crystal. We further study the time dynamics of the optical correlations in this system. This is the first demonstration of its kind in a solid and an enabling step toward realizing a solid-state quantum repeater. PMID:23609713

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

2013-04-22

228

Observation of coherent population transfer in a four-level tripod system with a rare-earth-metal-ion-doped crystal  

SciTech Connect

Coherent population transfer in a laser-driven four-level system in a tripod configuration is experimentally investigated with a rare-earth-metal-ion-doped crystal (Pr{sup 3+}:Y{sub 2}SiO{sub 5}). The population transfers observed here indicate that a main process inducing them is not optical pumping, which is an incoherent process inducing population transfer. Moreover, numerical simulation, which well reproduces the experimental results, also shows that the process inducing the observed population transfers is similar to stimulated Raman adiabatic passage (STIRAP) in the sense that this process possesses characteristic features of STIRAP.

Goto, Hayato; Ichimura, Kouichi [Frontier Research Laboratory, Corporate Research and Development Center, Toshiba Corporation, 1, Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, 212-8582 (Japan)

2007-03-15

229

An integral approach to regional gravity field refinement using earth gravity models  

NASA Astrophysics Data System (ADS)

The idea of this paper is to refine the terrestrial gravimetric data with the Earth's gravity models (EGMs) and produce a high quality source of gravity data. For this purpose, biased and unbiased integral estimators are presented. These estimators are used to refine gravimetric data over Fennoscandia with the ITG-GRACE2010s and GO_CONS_GCF_2_DIR_R2 EGMs, which are the recent products of the gravity field and climate experiment (GRACE) and the gravity field and steady-state ocean circulation explorer (GOCE) satellite missions. Numerical results show that the biased integral estimator has smaller global root mean square error (RMSE) than the unbiased one. Also a simple strategy is presented to down-weight the low-frequencies the terrestrial data in spectral combination. The gravity anomalies, computed by EGM08, are compared to the refined anomalies for evaluation purpose. In the case of using a cap size of 1° for integration the EGM08 gravity anomalies are more correlated with the refined ones. Also the band-limited kernels can simply be generated to maximum degree of the used EGMs for both estimators. Comparisons of the combined anomalies and those of EGM08 show insignificant differences between the biased and unbiased estimators in practice. However, the biased estimator seems to be proper one for gravity data refinement due to its smaller global RMSE.

Eshagh, Mehdi

2013-08-01

230

Observation of energy transfer from host to rare earth ions in Pr 3+-doped CdSiO 3 long-lasting phosphor  

NASA Astrophysics Data System (ADS)

The observation of energy transfer from host to rare earth ions in Pr 3+-doped CdSiO 3 long-lasting phosphor is reported in this Letter. The important role of persistent energy transfer from the CdSiO 3 host to the Pr 3+ is demonstrated experimentally through photoluminescence spectra, time-resolved emission spectra and fluorescence decay curves. A significant spectral overlap between the emission of host and the absorption of Pr 3+ (4d-5f) has been observed. By utilizing the principle of energy transfer, a promising approach for controlling the color-emitting is proposed to develop the multi-color long-lasting phosphors via persistence energy transfer from the long-lasting luminescent host to rare earth ions.

Kuang, Jinyong; Liu, Yingliang

2006-06-01

231

Release of AGAP Aerogeophysical Data through the Integrated Earth Data Applications Facility  

NASA Astrophysics Data System (ADS)

During the International Polar Year 2007 - 2009, scientists from six nations collaborated on a multi-disciplinary investigation of the Gamburtsevs, the least explored mountain range on Earth buried beneath the East Antarctic Ice Sheet, as part of the Antarctic Gamburtsev Province (AGAP) project. The AGAP project collected more than 120,000 line km of new aerogeophysical data using two Twin Otter aircraft. Data included ice penetrating radar, magnetometer, gravimeter and laser altimeter measurements. The main AGAP survey grid included north-south lines spaced 5 km apart, with crossing lines every 33 km and transects over the Vostok Subglacial Highlands, South Pole and southern Recovery lakes region. 150-MHz ice penetrating radars with bandwidths of 15 to 20 MHz measured ice thickness, bedrock topography, sub-ice hydrology, and produced high-resolution images of the internal structure of the East Antarctic Ice Sheet. Magnetic data map geologic structures across the mountain range, while gravity data provide new insights into the tectonic evolution and crustal thickness of the region. A swath-scanning laser altimeter with a spatial resolution of 2 meters measured elevation and details of the ice surface. Complete AGAP datasets are now in the process of becoming publicly available and freely accessible through the Java-based data visualization tool GeoMapApp (http://www.geomapapp.org), and the Antarctic & Southern Ocean Data Portal (http://www.marine-geo.org/tools/search/entry.php?id=AGAP_GAMBIT), both part of the Integrated Earth Data Applications (IEDA) Data Facility (http://www.iedadata.org) based at the Lamont-Doherty Earth Observatory of Columbia University. AGAP data will also be accessible through the Natural Environment Research Council (NERC) Polar Data Center, based at the British Antarctic Survey (http://www.antarctica.ac.uk/bas_research/data/index.php) and at the Center for the Remote Sensing of Ice Sheets (https://www.cresis.ku.edu/research/gambit).

O'hara, S. H.; Abdi, A.; Bonczkowski, J.; Bell, R. E.; Frearson, N.; Ferraccioli, F.; Corr, H.; Jordan, T. A.; Rose, K. C.; Studinger, M.; Gogineni, P. S.; Braaten, D. A.; Damaske, D.

2011-12-01

232

Integrating Earth System Science Data Into Tribal College and University Curricula  

NASA Astrophysics Data System (ADS)

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.

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

2007-12-01

233

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

NASA Technical Reports Server (NTRS)

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.

Vonfrese, R. R. B.; Hinze, W. J.; Braile, L. W.; Luca, A. J. (principal investigators)

1981-01-01

234

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

NASA Astrophysics Data System (ADS)

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.

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

235

Theoretical investigation of the more suitable rare earth to achieve high gain in waveguide based on silica containing silicon nanograins doped with either Nd³+ or Er³+ ions.  

PubMed

We present a comparative study of the gain achievement in a waveguide whose active layer is constituted by a silica matrix containing silicon nanograins acting as sensitizer of either neodymium ions (Nd3+) or erbium ions (Er3+). By means of an auxiliary differential equation and finite difference time domain (ADE-FDTD) approach that we developed, we investigate the steady states regime of both rare earths ions and silicon nanograins levels populations as well as the electromagnetic field for different pumping powers ranging from 1 to 104 mW/mm2. Moreover, the achievable gain has been estimated in this pumping range. The Nd3+ doped waveguide shows a higher gross gain per unit length at 1064 nm (up to 30 dB/cm) than the one with Er3+ doped active layer at 1532 nm (up to 2 dB/cm). Taking into account the experimental background losses we demonstrate that a significant positive net gain can only be achieved with the Nd3+ doped waveguide. PMID:24921348

Fafin, Alexandre; Cardin, Julien; Dufour, Christian; Gourbilleau, Fabrice

2014-05-19

236

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

PubMed

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

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

2014-02-28

237

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

PubMed

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

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

2014-02-15

238

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

E-print Network

A significant body of work on simulating the remote appearance of Earth-like exoplanets has been done over the last decade. The research is driven by the prospect of characterizing habitable planets beyond the Solar System in the near future. In this work, I present a method to produce the disk-integrated signature of planets that are described in their three-dimensional complexity, i.e. with both horizontal and vertical variations in the optical properties of their envelopes. The approach is based on pre-conditioned backward Monte Carlo integration of the vector Radiative Transport Equation and yields the full Stokes vector for outgoing reflected radiation. The method is demonstrated through selected examples inspired by published work at wavelengths from the visible to the near infrared and terrestrial prescriptions of both cloud and surface albedo maps. A clear advantage of this approach is that its computational cost does not appear to be significantly affected by non-uniformities in the planet optical pr...

Muñoz, A García

2014-01-01

239

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

PubMed

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

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

2014-01-01

240

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

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

241

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

NASA Astrophysics Data System (ADS)

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.

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

242

Density-functional study on the robust ferromagnetism in rare-earth element Yb-doped SnO2  

NASA Astrophysics Data System (ADS)

So far, little has been known about the ferromagnetism induced by p-f hybridization. We investigate the magnetic properties of Yb-doped SnO2 by first-principles calculations. We find that the doped system favors the ferromagnetic state and a room-temperature ferromagnetism can be expected in it. The origin of ferromagnetism can be attributed to the p-f hybridization between Yb impurity and its surrounding oxygen atoms. The formation energy of defect complex is calculated and the magnetic mediation of intrinsic vacancies is studied. Our results reveal that the formation energy of the defect complex with Sn vacancy is about 7.3 eV lower in energy than that with oxygen vacancy. This means Sn vacancy is much easier to form than oxygen vacancy in the presence of Yb substitution. The ferromagnetism of the doped system is greatly enhanced in the presence of Sn vacancies.

Zhang, Kai-Cheng; Li, Yong-Feng; Liu, Yong; Chi, Feng

2014-06-01

243

Plotnick et al. -Integrated Course for Elementary Education Majors 152 An Integrated Earth Science, Astronomy, and Physics Course for  

E-print Network

the fundamental concepts, principles and interconnections of the life, physical and earth/space sciences earth and space science, environmental science, biology, chemistry, and physics. For example science, biology, and astronomy; in other words, it both uses the world to illustrate physics and looks

Plotnick, Roy E.

244

Integrating Earth System Science Data Into Tribal College and University Curricula  

Microsoft Academic Search

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

P. J. Tilgner; D. J. Perkey

2007-01-01

245

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

ERIC Educational Resources Information Center

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…

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

246

Integrating Ecology and Environmental Ethics: Earth Stewardship in the Southern End of the Author(s): Ricardo Rozzi, Juan J. Armesto, Julio R. Gutirrez, Francisca Massardo, Gene E.  

E-print Network

Integrating Ecology and Environmental Ethics: Earth Stewardship in the Southern End of the AmericasScience · March 2012 / Vol. 62 No. 3 www.biosciencemag.org Integrating Ecology and Environmental Ethics: Earth Stewardship in the Southern End of the Americas RicaRdo Rozzi, Juan J. aRmesto, Julio R. GutiéRRez, FRancisca

Berkowitz, Alan R.

247

Fluorescence enhancement in rare earth doped sol-gel glass by N,N dimethylformamide as a drying control chemical additive  

NASA Astrophysics Data System (ADS)

Studies of terbium fluorescence intensity as a function of annealing temperature reveal the cause of increased fluorescence yields observed in rare earth doped sol-gel silicates prepared using N,N-dimethylformamide (DMF) as a drying control chemical additive (DCCA). While gels prepared with DMF actually have lower fluorescence yields than gels prepared without DMF at lower annealing temperatures, DMF gels can be annealed at much higher temperatures while retaining high optical quality. At these higher temperatures, terbium fluorescence yields increase dramatically as the sol-gel network undergoes densification, closing the pores of the network and eliminating the fluorescence quenching silanols on pore surfaces. DMF is therefore found to enhance the fluorescence properties of rare earth sol-gel glasses by reducing micro-fracturing and facilitating network densification. Further investigations are underway to determine the effectiveness of other promising DCCAs, such as glycerol, and to explore the possibility of exploiting the solubility properties of DCCAs to improve rare earth dopant dispersion.

Beyler, A. P.; Boye, D. M.; Hoffman, K. R.; Silversmith, A. J.

248

Ultra-broadband infrared luminescence of Bi-doped thin-films for integrated optics.  

PubMed

Ultra-broadband infrared luminescence has been observed in bismuth (Bi)-doped germanate thin-films prepared by pulsed laser deposition. The films are compatible with various types of substrates, including conventional dielectrics (LaAlO(3), silica) and semiconductors (Si, GaAs). The emission peak position of the films can be finely tuned by changing oxygen partial pressure during the deposition, while the excitation wavelength locates from ultra-violet to near-infrared regions. The physical mechanism behind the observed infrared luminescence of the Bi-doped films, differing from that of the as-made glass, is discussed. PMID:23938725

Xu, Beibei; Hao, Jianhua; Zhou, Shifeng; Qiu, Jianrong

2013-07-29

249

Dual function of rare earth doped nano Bi2O3: white light emission and photocatalytic properties.  

PubMed

Undoped Bi(2)O(3) and single and double doped Bi(2)O(3) : M (where M = Tb(3+) and Eu(3+)) nanophosphors were synthesized through a simple sonochemical process and characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), EDS, diffuse reflectance (DRS) and photoluminescence (PL) spectrophotometry. The TEM micrographs show that resultant nanoparticles have a rod-like shape. Energy transfer was observed from host to the dopant ions. Characteristic green emissions from Tb(3+) ions and red emissions from Eu(3+) ions were observed. Interestingly, the Commission International de l'Eclairage (CIE) coordinates of the double doped Bi(2)O(3) : Eu(3+)(0.8%) : Tb(3+)(1.2%) nanorods lie in the white light region of the chromaticity diagram and it has a quantum efficiency of 51%. The undoped Bi(2)O(3) showed a band gap of 3.98 eV which is red shifted to 3.81eV in the case of double doped Bi(2)O(3) : Eu(3+)(0.8%) : Tb(3+)(1.2%) nanorods. The photocatalytic activities of undoped nano Bi(2)O(3) and double doped nano Bi(2)O(3) : Eu(3+)(0.8%) : Tb(3+)(1.2%) were evaluated for the degradation of Rhodamine B under UV irradiation of 310 nm. The results showed that Bi(2)O(3) : Eu(3+)(0.8%) : Tb(3+)(1.2%) had better photocatalytic activity compared to undoped nano Bi(2)O(3). The evolution of CO(2) was realized and these results indicated the continuous mineralization of rhodamine B during the photocatalytic process. Thus double doped Bi(2)O(3) : Eu(3+)(0.8%) : Tb(3+)(1.2%) nanorods can be termed as a bifunctional material exhibiting both photocatalytic properties and white light emission. PMID:22791072

Dutta, Dimple P; Roy, Mainak; Tyagi, A K

2012-09-14

250

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

NASA Astrophysics Data System (ADS)

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.

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

2013-07-01

251

Application of doped rare-earth oxide TiO2:(Tm3+, Yb3+) in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Tm3+ and Yb3+ are codoped into TiO2 film in a dye-sensitized solar cell (DSSC). The emission and excitation spectra of TiO2:(Tm3+, Yb3+) power shows that the rare-earth ions possess up-conversion luminescence function, which results in harvesting more incident light and increasing photocurrent for the DSSC. On the other hand, owing to the p-type doping effect by Tm3+ and Yb3+, the photovoltage of the DSSC is enhanced. Under a simulated solar light irradiation of 100 mW·cm-2, a DSSC containing Tm3+/Yb3+ achieves a conversion efficiency of 7.05 %, which is increased by 10.0% compared with a DSSC lacking Tm3+/Yb3+.

Xie, Guixiang; Wei, Yuelin; Fan, Leqing; Wu, Jihuai

2012-01-01

252

Preparation, Analysis and Behaviors of Ti-Based SnO2 Electrode and the Function of Rare-Earth Doping in Aqueous Wastes Treatment  

NASA Astrophysics Data System (ADS)

Electrocatalytic anodes act as key function of electrocatalytic oxidation process for the removal of toxic or biorefractory materials. The characteristics of the anodes, such as potential for oxygen evolution, electric resistance, crystal size of the coating or the service life etc., have important impacts on the behavior of the electrodes. Titaniumbased tin dioxides electrode Ti / SnO2 found a kind of catalytic material with high oxygen evolution potential which related to the catalytic ability with the degradation of toxic material for aqueous wastes removal Four kinds of rare earth (Dy, Eu, Nd and Gd) were selected as doping agents to research the relationship between the electrocatalytic properties and the degradation pathway for organics degradation with the inner structure of the SnO2 crystals. The crystal structure of the electrode materials influence the properties of the anodes in many aspects and should be very important to understand the interplay mechanism for developing new kinds of catalytic electrodes.

Feng, Yujie; Liu, Junfeng; Ding, Haiyang

253

Multifunctional role of rare earth doping in optical materials: nonaqueous sol-gel synthesis of stabilized cubic HfO2 luminescent nanoparticles.  

PubMed

In this work a strategy for the control of structure and optical properties of inorganic luminescent oxide-based nanoparticles is presented. The nonaqueous sol-gel route is found to be suitable for the synthesis of hafnia nanoparticles and their doping with rare earths (RE) ions, which gives rise to their luminescence either under UV and X-ray irradiation. Moreover, we have revealed the capability of the technique to achieve the low-temperature stabilization of the cubic phase through the effective incorporation of trivalent RE ions into the crystal lattice. Particular attention has been paid to doping with europium, causing a red luminescence, and with lutetium. Structure and morphology characterization by XRD, TEM/SEM, elemental analysis, and Raman/IR vibrational spectroscopies have confirmed the occurrence of the HfO2 cubic polymorph for dopant concentrations exceeding a threshold value of nominal 5 mol %, for either Lu(3+) or Eu(3+). The optical properties of the nanopowders were investigated by room temperature radio- and photoluminescence experiments. Specific features of Eu(3+) luminescence sensitive to the local crystal field were employed for probing the lattice modifications at the atomic scale. Moreover, we detected an intrinsic blue emission, allowing for a luminescence color switch depending on excitation wavelength in the UV region. We also demonstrate the possibility of changing the emission spectrum by multiple RE doping in minor concentration, while deputing the cubic phase stabilization to a larger concentration of optically inactive Lu(3+) ions. The peculiar properties arising from the solvothermal nonaqueous synthesis here used are described through the comparison with thermally treated powders. PMID:23898781

Lauria, Alessandro; Villa, Irene; Fasoli, Mauro; Niederberger, Markus; Vedda, Anna

2013-08-27

254

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

PubMed

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

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

2014-06-01

255

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

SciTech Connect

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.

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

256

Integrating EarthScope Research and Education on a National Scale  

NASA Astrophysics Data System (ADS)

EarthScope's education and outreach mission is to ensure the EarthScope experiment creates as its legacy a public more knowledgeable and understanding of the scientific and societal contributions made by the EarthScope experiment and Earth science. It will fulfill this commitment by developing and disseminating products that utilize the data, models, technology and discoveries of EarthScope and that support existing education and outreach programs. EarthScope EON will carry out educational activities ranging from research experiences for students in grades K-16 to professional development for technical professionals and educators in both formal (e.g. K-20 classrooms) and informal (e.g. museums and parks) venues. It will also provide a wide range of outreach activities from organizing town halls or other local meetings in advance of an instrument deployment, to developing radio, print and video materials that inform the public about the EarthScope experiment and discoveries. The EarthScope Education and Outreach Network (EON) will be facilitated and coordinated through a national center; however, the bulk of the effort will be distributed among local EON alliances of various sizes designed to respond quickly and to meet the specific needs in a region. This allows EarthScope EON to provide customized services that engage culturally, economically and geographically diverse audiences at the national and local scales. The network will be built through national and local partnerships with existing science education and outreach programs at colleges, universities, research facilities and professional societies within the EarthScope community as well as relevant programs at museums and parks, state geologic surveys and emergency management agencies, and K-12 schools. These partnerships will allow EON to use existing resources, networks and expertise to gear up quickly and efficiently. As EON develops, it will reciprocate by contributing new resources and expertise to the partnerships that help improve public understanding of Earth systems overall and promote effective application of EarthScope discoveries.

Hall-Wallace, M. K.; Boyd, T.; Richard, G.; Ellins, K.; Meertens, C.; Semken, S.; Taber, J.; Benthien, M.; Wald, L.; Marvinney, R.

2002-12-01

257

Comparative study of pure and alkaline earth metallic doped cadmium mercury thiocyanate single crystals—Gel technique  

NASA Astrophysics Data System (ADS)

Growth aspects of Ba and Ca doped cadmium mercury thiocyanate (CMTC) single crystals from silica gel by the process of diffusion are discussed. The incorporation of dopants in the crystal has been confirmed by inductively coupled plasma (ICP) analysis. Single crystal X-ray diffraction studies reveal the structures of the doped crystals to be tetragonal implying that the incorporation of the dopants has not changed the structure of the parent crystal. The diffraction planes were identified and indexed by powder diffraction analysis. High-resolution X-ray diffraction analyses were carried out to investigate the crystalline perfection of the grown crystals. The grown crystals were characterized by Fourier transform infrared and transmission spectral analyses. Vickers microhardness studies on the grown crystals reveal that they belong to soft material category. Employing powder Kurtz method, their second harmonic generation efficiencies were measured in comparison with urea.

Kalainathan, S.; Kumari, P. Nisha Santha

2009-07-01

258

Preparation and up-conversion fluorescence of rare earth (Er{sup 3+} or Yb{sup 3+}/Er{sup 3+})-doped TiO{sub 2} nanobelts  

SciTech Connect

Anatase TiO{sub 2} nanobelts doped with rare earth (RE) ions Yb{sup 3+}, Er{sup 3+} or Yb{sup 3+}/Er{sup 3+} have been prepared using layered titanate nanobelts (LTO NBs) with RE ions as the precursor obtained by ion-exchange between LTO NBs and RE ions under hydrothermal process. Various measurement results demonstrate that the RE ions have doped into the lattice of TiO{sub 2}, and the Er{sup 3+} or Yb{sup 3+}/Er{sup 3+} doped nanobelts show strong visible up-conversion (UC) fluorescence under 980 nm excitation. The UC emission intensity of LTO NBs embedded with Er{sup 3+} or Yb{sup 3+}/Er{sup 3+} is slightly higher than that of the corresponding TiO{sub 2} nanobelts doped with RE ions, whereas higher RE doping content leads to the decrease of UC emission intensity due to the concentration-quenching effect. - Graphical abstract: Anatase TiO{sub 2} nanobelts doped with Er{sup 3+} or Yb{sup 3+}/Er{sup 3+} cations were simply synthesized using two-step preparation proceedings of ion-exchange and hydrothermal treatment, and their upconversion emissions were also investigated. SEM images of TiO{sub 2} nanobelts (NBs) doped with Er{sup 3+} (the left) and codoped with Yb{sup 3+}/Er{sup 3+} (the right).

Ji Tianhao, E-mail: jitianhao@th.btbu.edu.c [College of Chemical and Environmental Engineering, Beijing Technology and Business University, 11 Fucheng Road, Beijing 100048 (China); Liu Yang; Zhao Hui; Du Haiyan; Sun Jiayue [College of Chemical and Environmental Engineering, Beijing Technology and Business University, 11 Fucheng Road, Beijing 100048 (China); Ge Guanglu [National Center for Nanoscience and Technology, Beijing 100190 (China)

2010-03-15

259

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

SciTech Connect

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.

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

2012-03-21

260

Earth System Modeling—An Integrated Assessment Tool for Environmental Studies  

Microsoft Academic Search

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

R. A. PIELKE

261

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

Microsoft Academic Search

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

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

2010-01-01

262

An integrated study of earth resources in the state of California using remote sensing techniques. [water and forest management  

NASA Technical Reports Server (NTRS)

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.

Colwell, R. N.

1974-01-01

263

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

Microsoft Academic Search

Previous measurements of the scintillation properties of members of the single-alkali, rare-earth double-phosphate family have demonstrated high light output and fast decay times when exposed to ionizing radiation. Because of the ease with which the alkali constituents (Li, Na, K, Rb, Cs) of the crystal matrix may be interchanged (e.g. K2CsLu(PO4)2 and CsLi2Lu(PO4)2), the rare-earth double-phosphate family of scintillators provides

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

2007-01-01

264

Processing and Properties of Rare Earth Ion-Doped Bismuth Titanate Thin Films by Chemical Solution Deposition method  

Microsoft Academic Search

Ferroelectric (Bi,R)4Ti3O12 [R: rare earth] thin films were synthesized by the chemical solution deposition (CSD) method. Heat treatment above 600°C was required for the fabrication of crystalline (Bi,R)4Ti3O12 thin films of Bi-layered perovskite structure on Pt\\/TiOx\\/SiO2\\/Si substrates. The orientation of the films prepared at 750°C depended upon the kind of substituent rare earth ions. Bi4.12Ti3O12 (BIT) and Bi3.35La0.75Ti3O12 (BLT) thin

Mio Yamada; Naoya Iizawa; Toshiaki Yamaguchi; Wataru Sakamoto; Koichi Kikuta; Toshinobu Yogo; Takashi Hayashi; Shin-ichi Hirano

2003-01-01

265

Integrated microfluidic flowmeter based on a micro-FBG inscribed in Co2+-doped optical fiber.  

PubMed

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

Liu, Zhengyong; Tse, Ming-Leung Vincent; Zhang, A Ping; Tam, Hwa-Yaw

2014-10-15

266

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

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

267

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

E-print Network

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...

Nonsung, Sawat

2012-06-07

268

Empowering Rural Appalachian Youth Through Integrated Inquiry-based Earth Science  

NASA Astrophysics Data System (ADS)

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.

Cartwright, T. J.; Hogsett, M.

2009-05-01

269

Space-Based Sensor Web for Earth Science Applications: An Integrated Architecture for Providing Societal Benefits  

NASA Technical Reports Server (NTRS)

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.

Habib, Shahid; Talabac, Stephen J.

2004-01-01

270

Microfabrication of magnetostrictive beams based on NiFe film doped with B and Mo for integrated sensor systems  

NASA Astrophysics Data System (ADS)

This paper reports the development of integrated micro-sensors consisting of 1 -µm-thick magnetostrictive cantilevers or bridges with 500 µm in length and conducting interrogation elements. The thin films are fabricated by sputter deposition of NiFe doped with B and Mo, and the magnetic properties are enhanced by field annealing, resulting in a coercivity of 2.4 Oe. In operation, an alternating current applied to the interrogation elements magnetizes the magnetostrictive structures. The longitudinal resonant frequency is detected as an impedance change of the interrogation elements. The magnetostrictive micro-beams provide high resonant frequencies—2.95 MHz for the cantilever and 5.46 MHz for the bridge—which can be exploited to develop sensors of high sensitivity.

Alfadhel, A.; Gianchandani, Y.; Kosel, J.

2012-04-01

271

Diagnostics of doping integrity in n+/p/n+ transistor-channel structure by scanning nonlinear dielectric microscopy  

NASA Astrophysics Data System (ADS)

Scanning nonlinear dielectric microscopy was used to diagnose doping integrity in a transistor channel. The carrier state at various points in a pn junction was defined as n-type, p-type, or depletion through nonlinear capacitance (dC/dV) profiling and pinpoint capacitance-voltage analysis. Carrier state analysis was applied to the n+/p/n+ transistor channel of structures with different process parameters. An increase in the n+ activation temperature from 800 to 950 °C caused shrinkage in channel length of the p-type region. Decreasing the substrate acceptor concentration from 1018 to 1017 cm-3 caused depletion of the entire channel when the gate length was less than 200 nm.

Matsukawa, Takashi; Yasumuro, Chiaki; Masahara, Meishoku; Tanoue, Hisao; Kanemaru, Seigo

2004-04-01

272

Coastal DEMs integrate seafloor bathymetry and land topography to depict Earth's solid surface, and help us better understand a variety of ocean processes.  

E-print Network

Sheet What is a coastal DEM? A coastal DEM depicts Earth's land surface and ocean bottom. It is madeCoastal DEMs integrate seafloor bathymetry and land topography to depict Earth's solid surface, and help us better understand a variety of ocean processes. Coastal Digital Elevation Model (DEM) Fact

273

DataTools: A Professional Development Program Supporting the Integration of Technology and Scientific Data in Earth Science Classrooms  

NASA Astrophysics Data System (ADS)

The DataTools professional development program (http://serc.carleton.edu/eet/msdatatools) helps teachers integrate technology, scientific data, and inquiry into their middle and high school curricula. Over the course of the year-long program, teachers develop skills and a pedagogy of inquiry through a combination of on-line and face-to-face professional development and a significant amount of peer support. They learn to use information technologies that support the visualization and analysis of numerical, geospatial, and image data. Program staff continues working with teachers as they return to their classrooms to implement the program. DataTools leverages the resources and techniques of the Earth Exploration Toolbook (http://serc.carleton.edu/eet), an online collection of investigations that promotes the use of technology and scientific data in the context of studying the earth system. In this session we will describe the DataTools professional development program and the Earth Exploration Toolbook, and will share what we have learned over the past two years about the supports teachers need to successfully integrate the use of data and technology tools into their classrooms. We will also share some of the investigations that teachers have developed for use with their students.

Haddad, N.; Ledley, T. S.; McAuliffe, C.; Dahlman, L.

2008-12-01

274

Laboratory Earth Under the Lens: Diachronic Evaluation of an Integrated Graduate-Level On-Line Earth System Science Course Series for K-12 Educators  

NASA Astrophysics Data System (ADS)

Educational research strives to identify the pedagogies that promote student learning. However, the body of research identifying the characteristics of effective teacher preparation is "least strong for science," and is largely based on studies of the effectiveness of individual courses or workshops (NRC 2010). The National Research Council's "Preparing Teachers: Building Evidence for Strong Policy," (2010) provides a mandate for teacher education providers to conduct research on program-scale effectiveness. The high priority research agenda identified by the NRC is expected to elicit understanding of the aspects of teacher preparation that critically impact classroom student learning outcomes. The Laboratory Lens project is designed to identify effective practices in a teacher education program, with specific reference to the content domain of Earth science. Now in its fifth year, the Masters of Applied Science (MAS) program at UNL offers a variety of science courses, ranging from entomology to food science. The six-course Lab Earth series serves as the backbone of the Specialization for Science Educators within the MAS program, and provides comprehensive content coverage of all Earth science topics identified in the AAAS Benchmarks. "How People Learn," (NRC 2009) emphasizes that expert knowledge includes not only factual knowledge, but also the well-developed conceptual framework critical to the ability to, "remember, reason, and solve problems." A focus of our research is to document the process by which the transition from novice to expert takes place in Lab Earth's on-line teacher participants. A feature of our research design is the standardization of evaluation instruments across the six courses. We have used data derived from implementation of the Community of Inquiry Survey (COI) in pilot offerings to ensure that the course sequence is effective in developing a community of learners, while developing their content knowledge. A pre- and post- course Wilcoxan Signed Ranks Test is included in the battery of assessments to ensure that the courses achieve a statistically significant increase in participants' beliefs about their personal science teaching efficacy. The research design also includes the analysis of concept maps and content mastery assignments to assist in documentation of a teacher's transition from mastery of novice to expert knowledge. Content-based, course-specific pre and post knowledge surveys are included in the battery of assessments. In the analysis of on-line discussions, the project employs a textual analysis technique outlined in "The Rhetoric of Social Intervention," (RSI) (Opt and Gring 2009). RSI provides a promising analytical framework, especially when examining the development of understanding of scientific topics with societal implications, such as sustainability and climate change. The session provides a description of the integrated research design and data collection and analysis in the first year of this project.

Low, R.; Gosselin, D. C.; Haney, C.; Larson-Miller, C.; Bonnstetter, R.; Mandryk, C.

2012-12-01

275

Effect of rare-earth ion doping on the multiferroic properties of BiFeO3 thin films grown epitaxially on SrTiO3(1?0?0)  

NASA Astrophysics Data System (ADS)

High-quality epitaxial Bi1-xRExFeO3 (RE=La, Nd, Gd; x = 0, 0.05, 0.15) thin films were prepared on SrTiO3(1?0?0) substrates using pulsed laser deposition. X-ray diffraction and RBS-channelling spectroscopy showed that the films are single-phase perovskite, free of additional phases and textured with preferential orientation along the [1?0?0] direction. The dependences of magnetization on temperature and field showed that the films exhibit weak ferromagnetic properties. Among the studied rare-earth doping ions, Bi3+ substitution by Gd3+ most considerably enhanced the ferromagnetic properties. Substitution by La3+ smoothened out the surface morphology, which is important for different potential applications. Both undoped and doped films showed clear ferroelectric response in piezoresponse force microscopy, thus confirming their multiferroic nature. The doping was found to promote a preferential ferroelectric poling of the domains.

Lazenka, V. V.; Lorenz, M.; Modarresi, H.; Brachwitz, K.; Schwinkendorf, P.; Böntgen, T.; Vanacken, J.; Ziese, M.; Grundmann, M.; Moshchalkov, V. V.

2013-05-01

276

Continuous monitoring of a large active earth flow using an integrated GPS - automatic total station approach  

NASA Astrophysics Data System (ADS)

Landslide monitoring has evolved as a crucial tool in civil protection to mitigate and prevent disasters. The research presents an approach to continuous monitoring of a large-scale active earth flow using a system that integrates surface measurements obtained by a GPS and an automatic total station. With the data obtained from the system the landslide can be monitored in near-real-time and surface displacements can be directly utilized to provide early warning of slope movements and to study the behavior of the landslide, e.g. to predict timing and mechanisms of future failure. The Valoria landslide located in the northern Apennines of Italy was reactivated in 2001, 2005 and 2007 damaging roads and endangering houses. A monitoring system was installed in 2007-2008 in the frame of a civil protection plan aimed at risk mitigation. The system consists of an automatic total station measuring about 40 prisms located in the landslide to a maximum distance of 1.800 km; one double-frequency GPS receiver connects in streaming by wireless communication with 4 single-frequency GPS in side the flow. Until December 2007 the monitoring network was operated with periodic static surveying followed by the data post-processing. From September 2007 until March 2008 the landslide deformation was evaluated by periodic surveys with the total station and the GPS system. This first measure showed that the displacements were influenced by the rainfall events and by the snow melting. The total displacements measured vary from centimeter scale in the crown zone, where retrogressive movements were in progress, to over 50 m in the flow track zone. Starting in March 2008 data acquisition by the total station system and GPS were automated in order to allow continuous and near-real-time data processing. The displacement data collected in one and a half year of continuous operation show different acceleration and deceleration phases as a result of the pore water pressure distribution inside the landslide. From March 2008, the total station and the GPS receiver were predisposed for the continuous monitoring. The successive deformation continued constantly and some monitored points recorded decimeter of cumulative displacements in May. In June the displacements progressively decreased due to the absence of the precipitation. Abundant rainfalls in July 2008 (200 mm of rainfall in 50 days) drove a new instability in the landslide. As a result some landslide sectors experienced accelerations measuring total displacements between one decimeter and ten meters in 20 days. Following this event acceleration was recorded at the end of October 2008, when 550 mm of cumulative rain fell in 40 days. During this event the velocity of the material varied between cm/day to m/day and the maximum reacted displacement was 15 m. Through the monitoring with data acquisition every 3 hours it was also possible to evaluate the continuous transfer of mass from the upper part of the slope to lower part. Measurements showed the reactivation of a downslope portion only one day after reactivation occurred upslope at a distance 200 m. The utilized monitoring system has proven reliable for continuous monitoring of an active earth flow with large deformations ranging up to meters for day also during the paroxysmal phases. Moreover, the complex behavior of the flow in the active phase and in each acceleration and deceleration phase was highlighted. For instance, the timing and intensity of movement propagation downslope as an effect of mass transfer and successive loading of lower slope portions was evidenced many times. This information cannot be obtained with borehole monitoring systems which are normally damaged when displacement exceeds some decimeters, nor can it be computed with comparable spatial coverage and data availability timing using other high precision methods, such as laser scanners or ground-based SAR. Another advantage of the adopted monitoring approach over other techniques is the wide angle of operation provided by the strategically beneficial location of the master

Corsini, A.

2009-04-01

277

Learning in the Middle School Earth Science Classroom: Students Conceptually Integrate New Knowledge Using Intelligent Laserdiscs.  

ERIC Educational Resources Information Center

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…

Freitag, Patricia K.; Abegg, Gerald L.

278

INTEGRATING EARTH OBSERVATIONS DATA INTO GEOSPATIAL DATABASES THAT SUPPORT PUBLIC HEALTH DECISIONS  

Microsoft Academic Search

There are several reasons why public health communities do not use information from Earth observations routinely. Most notable among them are: (1) they need science results that verify, validate, and benchmark the statistical and economic benefits from these exotic inputs; and, (2) they lack the systems that would deliver such reliable information economically and swiftly in their already heavy workloads.

S. A. Morain; A. M. Budge

279

Structural and luminescence investigations on Sm 3+ doped sodium fluoroborate glasses containing alkali/alkaline earth metal oxides  

NASA Astrophysics Data System (ADS)

Structural and luminescence behavior of the Sm 3+ doped 49B 2O 3+25 xCO 3+25NaF+1Sm 2O 3, (where x=Li 2, Na 2, K 2, Ca and Mg) glasses have been studied and reported. Structural analysis of the prepared glasses was made through FTIR spectra and their optical properties were studied using optical absorption, luminescence and lifetime measurements. The bonding parameters and the oscillator strengths were determined from the absorption spectra. These parameters have been used to obtain the Judd-Ofelt parameters. Using the Judd-Ofelt parameters, radiative properties such as transition probability ( A), stimulated emission cross section (?PE) and branching ratio's ( ?R) for the trivalent samarium ions corresponding to their 4G 5/2? 6H J ( J=5/2, 7/2, 9/2 and 11/2) excited state transitions have been calculated and reported. The decay curve of the 4G 5/2? 6H 7/2 transition exhibits non-exponential behavior. The non-exponential behavior has been attributed to the energy transfer through cross-relaxation between adjacent Sm 3+ ions. The lifetime of the 4G 5/2 level is found to be comparatively less than that of the reported Sm 3+ glasses and the same is due to the presence of OH groups, which is confirmed through the FTIR spectral studies.

Arul Rayappan, I.; Selvaraju, K.; Marimuthu, K.

2011-02-01

280

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

NASA Astrophysics Data System (ADS)

We report on the enhancement in emission of NaYF4: Yb, Er upconverting nanoparticles (UCNPs) coated with a gold nanoshell. We have synthesized a doped NaYF4 core of 350 nm, with a sufficiently thick undoped NaYF4 shell of 65 nm thickness to minimize contact with the gold surface plasmons, and effectively minimizing luminescence quenching. Absorption and fluorescence emission measurements of single NaYF4 particles show enhanced absorption in the near infrared and a 1.5 times overall enhanced emission intensity. A relative increase in green/red emission was observed for both gold seed attachment and shell growth, of approximately 1.9 and 2.3 times respectively. Both Au seed attachment and shell growth has been shown to double the green/red emission ratio. The surface plasmon resonance of the UCNP core/Au shell composite is shown to be dependent on the gold shell thickness. Our experimental results are corroborated by finite element calculations.

Lim, Shuang; Li, Ling; Hallen, Hans

2013-03-01

281

Modeling the globally-integrated spectral variability of the Archean Earth: The purple planet  

NASA Astrophysics Data System (ADS)

Ongoing searches for exoplanetary systems have revealed a wealth of planets with diverse physical properties. Planets even smaller than the Earth have already been detected and the efforts of future missions are aimed at the discovery, and perhaps characterization, of small rocky exoplanets within the habitable zone of their stars. Clearly, what we know about our planet will be our guideline for the characterization of such planets. But the Earth has been inhabited for at least 3.8 Gyr and its appearance has changed with time. Here, we have studied the Earth during the Archean eon, 3 Gyr ago. At that time, one of the more widespread life forms on the planet were purple bacteria. These bacteria are photosynthetic microorganisms and can inhabit both aquatic and terrestrial environments. Here, we use a radiative transfer model to simulate the visible and near-infrared radiation reflected by our planet, taking into account several scenarios regarding the possible distribution of purple bacteria over continents and oceans. We find that purple bacteria have a reflectance spectrum that has a strong reflectivity increase, similar to the red edge of leafy plants, although shifted redward. This feature produces a detectable signal in the disk-averaged spectra of our planet, depending on cloud amount and bacteria concentration/ distribution. We conclude that by using multi-color photometric observations, it is possible to distinguish between an Archean Earth in which purple bacteria inhabit vast extensions of the planet and a present-day Earth with continents covered by deserts, vegetation, or microbial mats.

Palle, E.; Sanroma, E.; Parenteau, M. N.; Kiang, N. Y.; Gutierrez-Navarro, A. M.; Lopez, R.; Montañes-Rodríguez, P.

2014-03-01

282

Magnetization dynamics in rare earth Gd3+ doped Mn(0.5)Zn(0.5)Fe2O4 magnetic fluid: electron spin resonance study.  

PubMed

The electron spin resonance (ESR) technique has been applied to study the spin dynamics in broad temperature range for rare earth doped Mn(0.5)Zn(0.5)Fe(1.9)Gd(0.1)O(4) (MZG5) magnetic fluid. Zero field cooled (ZFC) ESR spectra of MZG5 fluid exhibit an isotropic shift in the resonance field below 40 K, while the field cooled (FC) ESR spectra show a deviation from sin(2)? behavior and an angle dependent hysteresis, this unambiguously points to the dominating unidirectional freezing of surface spins below 40 K. Above 60 K, the resonance field exhibits sin(2)? behavior, indicating the uniaxial anisotropy contribution of core spin. This indicates that surface spin freezing temperature is around 40 K. The presence of surface spin freezing and the coupling between core and surface spins are further supported by cycle dependent FC ESR spectra measured at 20 K, which show the systematic increase in resonance field (H(res)) and intensity. The double peak behavior of blocking temperature distribution retrieved from ZFC-FC magnetization measurement is an additional corroboration of the existence of surface spin glass like layer. PMID:23123769

Parekh, Kinnari; Upadhyay, R V

2012-12-01

283

Furnace Cyclic Behavior of Plasma-Sprayed Zirconia-Yttria and Multi-Component Rare Earth Oxide Doped Thermal Barrier Coatings  

NASA Technical Reports Server (NTRS)

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.

Zhu, Dongming; Nesbitt, James A.; McCue, Terry R.; Barrett, Charles A.; Miller, Robert A.

2002-01-01

284

Electrical behavior of some rare-earth-doped Nd 0.33Ln 0.34Sr 0.33MnO 3 manganites  

NASA Astrophysics Data System (ADS)

A series of rare-earth-doped Nd-Sr-Mn-O manganites having the compositional formula Nd 0.33Ln 0.34Sr 0.33MnO 3, (where Ln=Gd, Eu, Sm, Nd and Ce) were prepared by citrate-based sol-gel route with ethylene glycol as a gelating reagent. After characterizing the samples by X-ray diffraction and scanning electron microscopy, a systematic study of magnetic susceptibility, electrical resistivity and magnetoresistance has been carried out over a temperature range 80-300 K. The variation of both electrical and magnetic transition temperatures with average ionic radii of A-site cation is explained. The electrical resistivity data were analyzed using different theoretical models and it has been concluded that at low temperatures (ferromagnetic metallic region) the resistivity may originate from grain/domain boundary, electron-electron scattering and two-magnon scattering effects, while in the paramagnetic insulating regime, the variation of resistivity with temperature may be explained by adiabatic small polaron and variable-range hopping mechanisms. The values of activation energies are found to decrease, while the density of states at the Fermi-level, N( EF) are increasing with increasing < rA>. A suitable explanation for the observed behavior is given.

Padmavathi, K.; Venkataiah, G.; Venugopal Reddy, P.

2007-02-01

285

Superconductivity of metal nitride chloride ?-MNCl (M = Zr, Hf) with rare-earth metal RE (RE = Eu, Yb) doped by intercalation  

NASA Astrophysics Data System (ADS)

Electrons were doped into the ?-form layered metal nitride chloride MNCl (M = Zr, Hf) by intercalation of rare-earth metals RE (RE = Eu, Yb) using liquid ammonia solutions. The intercalated compounds REx(NH3)yMNCl show superconductivity with transition temperatures Tc of ˜13 and 24.3 K for M = Zr and Hf, respectively, quite similar to the alkali metal intercalated analogs. The paramagnetic characteristics for Eu2+ and Yb3+ can coexist with superconductivity. The magnetic resistance measured on the uniaxially oriented Eu0.08(NH3)yHfNCl with the magnetic field parallel to the ab plane (? ab) and the c axis (? c) shows a strong anisotropic effect on the upper critical field Hc2; a large anisotropic parameter \\gamma ={H}_{{c}2}^{\\parallel a b}/{H}_{{c}2}^{\\parallel c}\\sim 4 suggests a pseudo-two-dimensional superconductivity. The Tc of Eu0.13(THF)yHfNCl is shifted toward a higher value of 25.8 K upon expansion of the interlayer spacing from 11.9 to 17.5 Å by co-intercalation of voluminous organic molecules such as tetrahydrofuran.

Zhang, Shuai; Tanaka, Masashi; Onimaru, Takahiro; Takabatake, Toshiro; Isikawa, Yosikazu; Yamanaka, Shoji

2013-04-01

286

High contrast in vivo bioimaging using multiphoton upconversion in novel rare-earth-doped fluoride upconversion nanoparticles  

NASA Astrophysics Data System (ADS)

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.

Chen, Guanying; Yang, Chunhui; Prasad, Paras N.

2013-02-01

287

Bismuth Substitution for Rare Earth and Charge/Orbital Ordering Related Structural Effects in Some Half Hole-Doped Manganites  

NASA Astrophysics Data System (ADS)

The crystal and magnetic structures of the manganese oxide family Bi0.25RE0.25A0.5MnO3 (RE = La, Nd, Ho, Tm; A = Sr, Ca) were investigated by high resolution neutron diffraction. The half bismuth substitution for rare earth entails unusual structural distortions that make the manganese octahedra rather different from that in the non-substituted compounds. The findings for Ca-Bi manganites indicate an anisotropic expansion of the manganese octahedra and that the 6s2 lone electronic pair of Bi3+ cations is rather constrained than dominant. The CE-type antiferromagnetic ordering takes place in the Bi-Ca series while a part of the low temperature evidence for Bi-Sr members is in support to the phase separation conception.

Krezhov, Kiril A.

2007-04-01

288

[Study on self-propagating synthesis of the doped SrAl2O4 rare earth long afterglow phosphors].  

PubMed

Twenty one doped SrAl2O4 long after-glowed phosphors with 4 series were synthesized by self-propagating high-temperature synthesis method (SHS) with urea-nitrate solution which served as media at 600 degrees C. They are SrAl2O4: Eu(2+)0.012 5, RE(3+)0.012 5 (RE(3+) = Ce(3+), Pr(3+), Nd(3+), Tb(3+), Dy(3+)), SrAl2O4 : Eu(2+)0.012 5, M0.012 5 (M = Li(+), Be(2+), Cd(2+), Mn(2+), Cu(2+), Ag(+), Zn(2+), Pb(2+)), SrAl2O4 : Eu(2+)0.012 5, Dy(3+)0.012 5, M0.012 5 (M = Mn(2+), Cu(2+), Ag(+), Zn(2+)), and SrAlO4 = Eu(2+)0.012 5, Dy(3+)0.012 5, RE(3+)0.012 5 (RE(3+) = Ce(3+), Pr(3+), Nd(3+), Tb(3+)), of which luminescence and after-glowing features were tested. The morphology of all these samples presents a state of porosity and laxity. The samples show an intense emission peak at 514 nm and broad peaks of the excitation spectra at 290-360 nm, Tb(3+) and Dy(3+) had most effects on luminance and after-glowed time respectively. The SrAl2O4 : Eu(2+)0.012 5, Dy(3+)0.012 5 had good luminance and proper after-glowed time as well. PMID:21847911

Li, Yuan; Zhao, Yong-Liang; Liu, Yong-Gang; Wei, Xiao-Yan; Ren, Yue

2011-06-01

289

Integrated experimental and modeling study of the ionic conductivity of samaria-doped ceria thin films  

SciTech Connect

Oxygen diffusion and ionic conductivity of samaria-doped ceria (SDC) thin films have been studied as a function of composition using experiment and atomistic simulation. SDC thin films were grown on Al2O3 (0001) substrates by oxygen plasma-assisted molecular beam epitaxy (OPA-MBE) technique. The experimental results show a peak in electrical conductivity of SDC at 15 mol% Sm2O3. The oxygen diffusion coefficient obtained from molecular dynamics simulation of the same system shows a peak at about 13 mol% Sm2O3. The activation energy for oxygen diffusion was found to be in the range from 0.8 to 1.0 eV by simulations depending on the Sm2O3 content, which compares well with the range from 0.6 to 0.9 eV given by the experimental work. The simulations also show that oxygen vacancies prefer Sm3+ ions as first neighbors over Ce4+ ions. The present results reveal that the optimum samaria content for ionic conductivity in single crystals of SDC is less than that in polycrystals, which can be related to the preferential segregation of dopant cations to grain boundaries in polycrystals.

Sanghavi, Rahul P.; Devanathan, Ramaswami; Nandasiri, Manjula I.; Kuchibhatla, Satyanarayana V N T; Kovarik, Libor; Thevuthasan, Suntharampillai; Prasad, Shalini

2011-12-12

290

Formation of an integrated holding company to produce rare-earth metal articles  

NASA Astrophysics Data System (ADS)

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.

Bogdanov, S. V.; Grishaev, S. I.

2013-12-01

291

Sun-, Earth- and Moon-integrated simulation ray tracing for observation from space using ASAP  

NASA Astrophysics Data System (ADS)

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.

Breault, Robert P.; Kim, Sug-Whan; Yang, Seul-Ki; Ryu, Dongok

2014-09-01

292

Integrating Real-time, Real-world Geoscience Experiences into Classroom Instruction with EarthLabs and the JOIDES Resolution  

NASA Astrophysics Data System (ADS)

Inspiring the next generation of geoscientists and preparing students for the 21st century workforce requires lifting science outside of the classroom and giving learners the opportunity to think critically about real-world geoscience problems. The EarthLabs suite of climate science modules challenges students with a variety of learning experiences including current scientific data analysis, computer visualizations, satellite imagery, and engaging videos. Each module includes a series of hands-on activities to allow students to explore Earth's complex and dynamic climate history, leading to a deeper understanding of present and future changes to our planet. A new EarthLabs module in development 'Climate Detectives: An Expedition on board the JOIDES Resolution," focuses on Integrated Ocean Drilling Program (IODP) Expedition 341 to Southern Alaska. The module is structured to allow students to work collaboratively, mimicking scientific research groups on the JOIDES Resolution. As students assume the role of a scientist, learn about data collection methods, and analyze authentic data, they learn about the climate history and tectonic processes of the Southern Alaska continental margin, as well as explore the relationship between climate, sedimentation, and tectonics. The Project Based Learning (PBL) approach used in the module teaches students how to analyze data and solve problems like scientists, strengthening the development of higher order thinking skills and preparing them for college coursework. The 'Climate Detectives' Module also provides students with opportunities to interact with scientists through live video conferencing and pre-recorded video presentations by scientists. In this presentation, Expedition 341 Education Officer, Alison Mote, describes the new module, which takes students on an educational journey as they learn about the scientific objectives, methods, and data collection tools scientists use to conduct research on sediment cores retrieved from beneath the seafloor in the Gulf of Alaska during summer 2013. Students discover how we know what we know about the Earth through the lens of scientific ocean drilling.

Mote, A. S.; Lockwood, J.; Ellins, K. K.; Haddad, N.; Cooper, S. K.; Ledley, T. S.

2013-12-01

293

Integrated Earth Science Research in Deep Underground Science and Engineering Laboratories  

NASA Astrophysics Data System (ADS)

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.

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

2004-12-01

294

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

PubMed

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

Ishiwada, Naohiro; Ueda, Toshihisa; Yokomori, Takeshi

2011-01-01

295

Earth Sciences Earth Sciences  

E-print Network

Earth Sciences Earth Sciences Undergraduate Studies #12;Department of Earth Sciences2 Royal;3Department of Earth Sciences Earth Sciences The Department of Earth Sciences at Royal Holloway.ac.uk/studyhere Contents Why study Earth Sciences? 4 Earth Sciences at Royal Holloway 5 Admissions and entry requirements 6

Royal Holloway, University of London

296

Path Integral Monte Carlo study confirms a highly ordered snowball in $^4$He nanodroplets doped with an Ar$^+$ ion  

E-print Network

By means of the exact Path Integral Monte Carlo method we have performed a detailed microscopic study of 4He nanodroplets doped with an argon ion, Ar$^+$, at $T=0.5$ K. We have computed density profiles, energies, dissociation energies and characterized the local order around the ion for nanodroplets with a number of 4He atoms ranging from 10 to 64 and also 128. We have found the formation of a stable solid structure around the ion, a "snowball", consisting of 3 concentric shells in which the 4He atoms are placed on at the vertices of platonic solids: the first inner shell is an icosahedron (12 atoms); the second one is a dodecahedron with 20 atoms placed on the faces of the icosahedron of the first shell; the third shell is again an icosahedron composed of 12 atoms placed on the faces of the dodecahedron of the second shell. The "magic numbers" implied by this structure, 12, 32 and 44 helium atoms, have been observed in a recent experimental study [Bartl et al, J. Phys. Chem. A 118, 2014] of these complexes;...

Tramonto, Filippo; Nava, Marco; Galli, Davide E

2014-01-01

297

Effect of Knowledge Integration Activities on Students' Perception of the Earth's Crust as a Cyclic System.  

ERIC Educational Resources Information Center

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…

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

2003-01-01

298

Implementing an end-to-end integration of Earth system science in post-secondary education  

Microsoft Academic Search

Bowie State University has made significant steps in integration of geoscience and remote sensing research in its development of educational programs containing education, hands-on training and research. Much of this effort is made to attract more students to science and technology disciplines and also to better prepare students for successful competition in the high tech market of the local industry

M. Mareboyana; Nagi T. Wakim; William T. Lawrence

1999-01-01

299

Preparation conditions and optical properties of rare earth ion (Er{sup 3+} and Eu{sup 3+})-doped alumina films by the aqueous sol{endash}gel method  

SciTech Connect

Transparent alumina and rare earth ion (Er{sup 3+} and Eu{sup 3+}) highly doped alumina films (15 mol%) were prepared by the aqueous sol{endash}gel method, in order to examine the effects of various preparation conditions on the structure and optical properties of doped films. The results showed that when the gel was heat treated, it lost free and bound water and was converted into the oxide by way of a series of intermediate phases although the oxide as a whole remained structureless. The thermogravimetric analysis curve showed a marked weight loss in the temperature range of 100{endash}500{degree}C and the slow loss continuing at higher temperature of 800{degree}C. High doping may reflect noncrystalline structure of alumina. The fluorescence of Eu{sup 3+} sensitive of microstructure increased especially corresponding to this weight loss with treatment. The {Omega}{sub 2} indicative of the asymmetric environment of Er{sup 3+} showed a similar increase. Concentration quenching for doped films treated at 800{degree}C was not significant in this concentration range. Lifetimes increased with increasing treatment temperature, similar to above increase. {copyright} 2001 American Institute of Physics.

Ishizaka, T.; Kurokawa, Y.

2001-07-01

300

An integrated study of earth resources in the state of California based on ERTS-1 and supporting aircraft data  

NASA Technical Reports Server (NTRS)

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.

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

301

Discover Earth  

NASA Technical Reports Server (NTRS)

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.

Steele, Colleen

1998-01-01

302

Improvement of structural integrity and battery performance of LiNi 0.5Mn 0.5O 2 by Al and Ti doping  

NASA Astrophysics Data System (ADS)

LiNi 0.5Mn 0.5O 2, LiNi 0.475Al 0.05Mn 0.475O 2, and LiNi 0.5Mn 0.45Ti 0.05O 2 were prepared via the emulsion drying method. The as-prepared materials showed different degrees of cation mixing. Rietveld refinement of X-ray diffraction data revealed that Al and Ti doping in LiNi 0.5Mn 0.5O 2 was significantly effective to decrease the cation mixing in the octahedral Li layers. The cation mixing consequently affected to the charge and discharge capacities. The irreversible capacity was the smallest for the Al doped LiNi 0.5Mn 0.5O 2, which showed the smallest cation mixing. Al and Ti doped LiNi 0.5Mn 0.5O 2 delivered a stable capacity of about 175 mAh g -1 with high reversibility. Such higher capacities were possible to be obtained by the achievement of structural stabilization and enhancement of structural integrity by Al and Ti doping in LiNi 0.5Mn 0.5O 2.

Myung, Seung-Taek; Komaba, Shinichi; Hirosaki, Norimitsu; Hosoya, Kiyoharu; Kumagai, Naoaki

303

MEOS Microsatellite Earth Observation using Miniature Integrated-Optic IR Spectrometers  

NASA Astrophysics Data System (ADS)

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

Kruzelecky, Roman

304

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

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.

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

2013-03-15

305

The NASA A-Train and the Next Generation of Earth Science Data Integration  

NASA Astrophysics Data System (ADS)

The A-Train is a succession of six U.S. and international sun-synchronous orbit satellites seconds to minutes apart across the 1:30 p.m. local afternoon equator crossing time according to the sequence: Orbiting Carbon Observatory (OCO), EOS Aqua, CloudSat, Polarization & Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar (PARASOL), CALIPSO, and EOS Aura. Flying in such a formation increases the number of observations and enables coordination between science observations, resulting in a more complete virtual science platform. The A-Train formation will allow for synergistic measurements where data from several different satellites can be used together to obtain comprehensive information about various key atmospheric components or processes. This combined information from several sources will give a more complete answer to many questions than would be possible from any single satellite. In order to take advantage of this unique opportunity, the NASA Goddard Space Flight Center (GSFC) Earth Sciences (GES), Data and Information Services Center (DISC) is building an A-Train Data Depot (ATDD) to process, archive, access, visualize, analyze and correlate distributed atmosphere measurements from various instruments along A-Train tracks. The ATDD will enable the seamless access to remotely located A-Train data, so that they can be combined to create a consolidated vertical view of the Earth's Atmosphere along the flying tracks. Once the infrastructure of the ATDD is in place, it can be easily evolved to serve data from all A-Train data measurements as a one-stop shopping that will save time and improve efficiency. Users interest in Atmospheric Chemistry, and Water and Energy Science will have a clear connection with their data of interest by being able to access the specific subset (parameter, spatial, and temporal) of interest. This presentation will describe the initial efforts at the GES/DISC in the development of the ATDD portal beginning with the CloudSat products and subsetting services from the CloudSat data processing facility at the Cooperative Institute for Research in the Atmosphere (CIRA). The project combines data from the AQUA MODIS instrument with the CloudSat 94 GHz cloud imaging radar and serves as a benchmark to the challenges facing the full development and implementation of the ATDD. The main issues to be discussed include ground track matching to determine the MODIS pixel closest to the CloudSat ground track, management of pixel resolution differences, compensation for orbital variations, etc.

Vicente, G. A.; Kempler, S.; Smith, P.; Tewari, K.; Kummerer, R.; Leptoukh, G.; Stephens, G.; Partain, P.; Reinke, D.

2005-12-01

306

Integrated Solid Earth Science: the right place and time to discover the unexpected? (Arthur Holmes Medal Lecture)  

NASA Astrophysics Data System (ADS)

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

Cloetingh, Sierd

2013-04-01

307

Integration of lessons from recent research for "Earth to Mars" life support systems  

NASA Astrophysics Data System (ADS)

Development of reliable and robust strategies for long-term life support for mbox planetary exploration needs to be built on real-time experimentation to verify and improve system components Also critical is the incorporation of a range of viable options to handle potential short-term life system imbalances This paper revisits some of the conceptual framework for a Mars base prototype previously advanced Mars on Earth in the light of three years of experimentation by the authors in the Laboratory Biosphere further investigation of system alternatives and the advent of other innovative engineering and agri-ecosystem approaches Several experiments with candidate space agriculture crops have demonstrated the higher productivity possible with elevated light levels and improved environmental controls For example crops of sweet potatoes exceeded original Mars base prototype projections by 83 ultradwarf Apogee wheat by 27 pinto bean by 240 and cowpeas slightly exceeded anticipated dry bean yield These production levels although they may be increased with further optimization of lighting regimes environmental parameters crop density etc offer evidence that a soil-based system can be as productive as the hydroponic systems which have dominated space life support scenarios and research Soil also offers several distinct advantages the capability to be created using in-situ space resources reducing reliance on consumables and imported resources and more easily recycling and

Nelson, M.; Allen, J. P.; Alling, A.; Dempster, W. F.; Silverstone, S.; van Thillo, M.

308

Toward a better integration of biological data from precipitation manipulation experiments into Earth system models  

NASA Astrophysics Data System (ADS)

biological responses to precipitation within the terrestrial components of Earth system models, or land surface models (LSMs), are mechanistically simple and poorly constrained, leaving projections of terrestrial ecosystem functioning and feedbacks to climate change uncertain. A number of field experiments have been conducted or are underway to test how changing precipitation will affect terrestrial ecosystems. Results from these experiments have the potential to vastly improve modeled processes. However, the transformation of experimental results into model improvements still represents a grand challenge. Here we review the current state of precipitation manipulation experiments and the precipitation responses of biological processes in LSMs to explore how these experiments can help improve model realism. First, we discuss contemporary precipitation projections and then review the structure and function of current-generation LSMs. We then examine different experimental designs and discuss basic variables that, if measured, would increase a field experiment's usefulness in a modeling context. Next, we compare biological processes commonly measured in the field with their model analogs and find that, in many cases, the way these processes are measured in the field is not compatible with the way they are represented in LSMs, an effect that hinders model development. We then discuss the challenge of scaling from the plot to the globe. Finally, we provide a series of recommendations aimed to improve the connectivity between experiments and LSMs and conclude that studies designed from the perspective of researchers in both communities will provide the greatest benefit to the broader global change community.

Smith, Nicholas G.; Rodgers, Vikki L.; Brzostek, Edward R.; Kulmatiski, Andrew; Avolio, Meghan L.; Hoover, David L.; Koerner, Sally E.; Grant, Kerstin; Jentsch, Anke; Fatichi, Simone; Niyogi, Dev

2014-09-01

309

Towards Designing an Integrated Earth Observation System for the Provision of Solar Energy Resource and Assessment  

NASA Technical Reports Server (NTRS)

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.

Stackouse, Paul W., Jr.; Renne, D.; Beyer, H.-G.; Wald, L.; Meyers, R.; Perez, R.; Suri, M.

2006-01-01

310

Visual-vestibular integration as a function of adaptation to space flight and return to Earth  

NASA Technical Reports Server (NTRS)

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.

Reschke, Millard R.; Bloomberg, Jacob J.; Harm, Deborah L.; Huebner, William P.; Krnavek, Jody M.; Paloski, William H.; Berthoz, Alan

1999-01-01

311

Research priorities in land use and land-cover change for the Earth system and integrated assessment modelling  

SciTech Connect

This special issue has highlighted recent and innovative methods and results that integrate observations and AQ3 modelling analyses of regional to global aspect of biophysical and biogeochemical interactions of land-cover change with the climate system. Both the Earth System and the Integrated Assessment modeling communities recognize the importance of an accurate representation of land use and land-cover change to understand and quantify the interactions and feedbacks with the climate and socio-economic systems, respectively. To date, cooperation between these communities has been limited. Based on common interests, this work discusses research priorities in representing land use and land-cover change for improved collaboration across modelling, observing and measurement communities. Major research topics in land use and land-cover change are those that help us better understand (1) the interaction of land use and land cover with the climate system (e.g. carbon cycle feedbacks), (2) the provision of goods and ecosystem services by terrestrial (natural and anthropogenic) land-cover types (e.g. food production), (3) land use and management decisions and (4) opportunities and limitations for managing climate change (for both mitigation and adaptation strategies).

Hibbard, Kathleen A.; Janetos, Anthony C.; Van Vuuren, Detlef; Pongratz, Julia; Rose, Steven K.; Betts, Richard; Herold, Martin; Feddema, Johannes J.

2010-11-15

312

Structural and optical properties of rare earth-doped (Ba{sub 0.77}Ca{sub 0.23}){sub 1-x}(Sm, Nd, Pr, Yb){sub x}TiO{sub 3}  

SciTech Connect

The structural, dielectric, and vibrational properties of pure and rare earth (RE)-doped Ba{sub 0.77}Ca{sub 0.23}TiO{sub 3} (BCT23; RE = Nd, Sm, Pr, Yb) ceramics obtained via solid-state reaction were investigated. The pure and RE-doped BCT23 ceramics sintered at 1450 deg. C in air for 4 h showed a dense microstructure in all ceramics. The use of RE ions as dopants introduced lattice-parameter changes that manifested in the reduction of the volume of the unit cell. RE-doped BCT23 samples exhibit a more homogenous microstructure due to the absence of a Ti-rich phase in the grain boundaries as demonstrated by scanning electron microscopy imaging. The incorporation of REs led to perturbations of the local symmetry of TiO{sub 6} octahedra and the creation of a new Raman mode. The results of Raman scattering measurements indicated that the Curie temperature of the ferroelectric phase transition depends on the RE ion and ion content, with the Curie temperature shifting toward lower values as the RE content increases, with the exception of Yb{sup 3+} doping, which did not affect the ferroelectric phase transition temperature. The phase transition behavior is explained using the standard soft mode model. Electronic paramagnetic resonance measurements showed the existence of Ti vacancies in the structure of RE-doped BCT23. Defects are created via charge compensation mechanisms due to the incorporation of elements with a different valence state relative to the ions of the pure BCT23 host. It is concluded that the Ti vacancies are responsible for the activation of the Raman mode at 840 cm{sup -1}, which is in agreement with lattice dynamics calculations.

Moraes, A. P. A. [Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, 60455-900 Fortaleza-CE (Brazil); Universidade Federal do Mato Grosso, 78060-900, Araguaia-MT (Brazil); Filho, A. G. Souza; Freire, P. T. C.; Filho, J. Mendes [Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, 60455-900 Fortaleza-CE (Brazil); M'Peko, J. C.; Hernandes, A. C. [Grupo de Crescimento de Cristais e Materiais Ceramicos, Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, Caixa Postal 369, Sao Carlos-SP (Brazil); Antonelli, E. [Universidade Federal de Itajuba (Unifei) - Campus Itabira, Rua Sao Paulo 377, Bairro Amazonas, CEP35900-37 Itabira, MG (Brazil); Blair, Michael W.; Muenchausen, Ross E. [Los Alamos National Laboratory, Materials Science and Technology Division, Los Alamos, New Mexico 87545 (United States); Jacobsohn, Luiz G. [Center for Optical Materials Science and Engineering Technologies - COMSET, and School of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634 (United States); Paraguassu, W. [Faculdade de Fisica, Universidade Federal do Para, 66075-110, Belem-PA (Brazil)

2011-06-15

313

Laser Spectroscopy of Defect Chemistry in Rare Earth Doped Strontium-Chloride and Mechanism of Energy Transfer Between Ions in STRONTIUM-FLUORIDE:ERBIUM(3+)  

NASA Astrophysics Data System (ADS)

Site selective laser spectroscopy has been used to identify the sites in SrCl(,2):Eu('3+), and follow their changes with concentration and annealing temperature. The Eu('3+) lines have been classified into nine major sites. A cubic site compensated distantly, two pair sites compensated locally, and six clusters were observed. The site distribution changed markedly as a function of dopant concentration from 3.7 x 10('-5) to 0.11 mol % Eu('3+). At low concentrations the pair sites increased relative to the cubic site with Eu('3+) concentration as expected from a simple mass action equilibrium relationship. Above 2 x 10('-3) mol % Eu('3+) clusters become important and the pairs decrease relative to the cubic site with increasing Eu('3+) concentration. When crystals with significant concentrations of clusters are annealed, the pair sites increase relative to the cubic site, and cluster VI increases relative to the other clusters, but the clusters cannot be eliminated even at high annealing temperatures. This behavior is contrary to that expected from simple mass action equilibrium relationships, but similar to that found in the alkaline earth fluorides. The observation of the anomalous behavior in SrCl(,2):Eu('3+) which has the fluorite structure, but no fluoride ions, eliminates the possibility that the anomalous behavior in the fluorides is due to F('-) ions. Similar sites were observed when crystals with low concentrations of Eu('3+) were doubly doped with La('3+), Gd('3+), and Yb('3+). The dependence of the Eu('3+) linewidths, and the pair/cubic site ratio, on ion size was investigated. The temperature and magnetic field dependence of the nonresonant energy transfer rate is measured for two ions that exist in a well-defined dimer in SrF(,2)Er('3+). The two ions are crystallographically inequivalent so the energy transfer can be observed directly and unique transfer rates are obtained without modeling the radial dependence of the transfer rate. The transfer is shown to result from a single phonon assisted process at low temperature and a two phonon assisted resonant or Orbach process at higher temperatures. No evidence is found for two phonon nonresonant processes.

Wietfeldt, John Rudolph

314

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...

315

MODELING THE DYNAMICS OF THE INTEGRATED EARTH SYSTEM AND THE VALUE OF GLOBAL ECOSYSTEM SERVICES USING THE GUMBO MODEL. (R827169)  

EPA Science Inventory

A global unified metamodel of the biosphere (GUMBO) was developed to simulate the integrated earth system and assess the dynamics and values of ecosystem services. It is a `metamodel' in that it represents a synthesis and a simplification of several existing dynamic gl...

316

Multidisciplinary integrated field campaign to an acidic Martian Earth analogue with astrobiological interest: Rio Tinto  

NASA Astrophysics Data System (ADS)

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.

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

317

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

318

Expedition Earth and Beyond: Using NASA Data Resources and Integrated Educational Strategies to Promote Authentic Research in the Classroom  

NASA Technical Reports Server (NTRS)

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.

Graffi, Paige Valderrama; Stefanov, William; Willis, Kim; Runco, Sue

2009-01-01

319

Expedition Earth and Beyond: Using NASA data resources and integrated educational strategies to promote authentic research in the classroom  

NASA Astrophysics Data System (ADS)

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.

Graff, P. V.; Stefanov, W.; Willis, K.; Runco, S.

2009-12-01

320

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

PubMed Central

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

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

2012-01-01

321

Thermal neutron imaging with rare-earth-ion-doped LiCaAlF 6 scintillators and a sealed 252Cf source  

NASA Astrophysics Data System (ADS)

Thermal neutron imaging with Ce-doped LiCaAlF 6 crystals has been performed. The prototype of the neutron imager using a Ce-doped LiCaAlF 6 scintillating crystal and a position sensitive photomultiplier tube (PSPMT) which had 64 multi-channel anode was developed. The Ce-doped LiCaAlF 6 single crystal was grown by the Czochralski method. A plate with dimensions of a diameter of 50×2 mm 2 was cut from the grown crystal, polished, and optically coupled to PSPMT by silicone grease. The 252Cf source (<1 MBq) was sealed with 43 mm of polyethylene for neutron thermalization. Alphabet-shaped Cd pieces with a thickness of 2 mm were used as a mask for the thermal neutrons. After corrections for the pedestals and gain of each pixel, we successfully obtained two-dimensional neutron images using Ce-doped LiCaAlF 6.

Kawaguchi, Noriaki; Yanagida, Takayuki; Fujimoto, Yutaka; Yokota, Yuui; Kamada, Kei; Fukuda, Kentaro; Suyama, Toshihisa; Watanabe, Kenichi; Yamazaki, Atsushi; Chani, Valery; Yoshikawa, Akira

2011-10-01

322

A Critical Path for Data Integration in the U.S. Earth Sciences  

NASA Astrophysics Data System (ADS)

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.

Gallagher, K. T.; Allison, M. L.

2011-12-01

323

Theoretical investigation of the more suitable rare earth to achieve high gain in waveguide based on silica containing silicon nanograins doped with either Nd3+ or Er3+ ions  

E-print Network

We present a comparative study of the gain achievement in a waveguide whose active layer is constituted by a silica matrix containing silicon nanograins acting as sensitizer of either neodymium ions (Nd3+) or erbium ions (Er3+). By means of an auxiliary differential equation and finite difference time domain (ADE-FDTD) approach that we developed, we investigate the steady states regime of both rare earths ions and silicon nanograins levels populations as well as the electromagnetic field for different pumping powers ranging from 1 to 104 mW/mm2. Moreover, the achievable gain has been estimated in this pumping range. The Nd3+ doped waveguide shows a higher gross gain per unit length at 1064 nm (up to 30 dB/cm) than the one with Er3+ doped active layer at 1532 nm (up to 2 dB/cm). Taking into account the experimental background losses we demonstrate that a significant positive net gain can only be achieved with the Nd3+ doped waveguide.

Fafin, Alexandre; Dufour, Christian; Gourbilleau, Fabrice

2014-01-01

324

Google Earth as a Vehicle to Integrating Multiple Layers of Environmental Satellite Data for Weather and Science Applications  

NASA Astrophysics Data System (ADS)

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.

Turk, F. J.; Miller, S. D.

2007-12-01

325

Selective Emitter Pumped Rare Earth Laser  

NASA Technical Reports Server (NTRS)

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.

Chubb, Donald L. (Inventor); Patton, Martin O. (Inventor)

2001-01-01

326

Modal cutoff in rare-earth-doped photonic crystal fibers with multi-layer air-holes missing in the core  

NASA Astrophysics Data System (ADS)

The various mode effective indices of the doped photonic crystal fibers (PCFs) are compared, the mode field distributions of the fundamental mode and the second-order mode are analyzed, and the single-mode condition is presented. The mode effective indices of large-core doped PCFs with different core indices and structure parameters are simulated by the finite element method (FEM). The relations of the core index with the fiber structure parameters of pitch, hole-to-pitch ratio and core diameter are obtained for single-mode propagation. In the design and fabrication of the doped PCF, we can adjust the core index and fiber structure parameters to achieve large mode area and single-mode propagation.

Zhao, Xing-tao; Zheng, Yi; Liu, Xiao-xu; Li, Shu-guang; Han, Ying; Hou, Zhi-yun; Wang, Na; Hou, Lan-tian

2013-05-01

327

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)

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.

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

2014-05-01

328

White light luminous properties and energy transfer mechanism of rare earth ions in Ce3+/Tb3+/Sm3+ co-doped glasses  

NASA Astrophysics Data System (ADS)

We report on a kind of Ce3+/Tb3+/Sm3+ co-doped borosilicate glasses which can emit white light luminescence combined with red, green and blue fluorescence. In this manuscript, the energy transfer mechanism between Ce3+ and Tb3+ ions, Ce3+ and Sm3+ ions, and Tb3+ and Sm3+ ions is discussed by analysis of the steady and transient luminescence spectra of the doped ions. Based on the energy transfer mechanism, the near-ideal white light emission from the Ce3+/Tb3+/Sm3+ co-doped glasses with the color coordinate ( x=0.335, y=0.337) has been observed under 350-nm excitation. Meanwhile, the calculated parameters such as color rendering index (78-81) and color temperature (4717-5372 K), characterizing luminous properties, show that the glasses can be potential candidates for displays and lighting.

Chen, Qiaoqiao; Dai, Nengli; Liu, Zijun; Chu, Yingbo; Ye, Baoyuan; Li, Haiqing; Peng, Jinggang; Jiang, Zuowen; Li, Jinyan; Wang, Fang; Yang, Luyun

2014-06-01

329

Advancing Access, Attribution, and Integration of Earth & Ocean Science Data: Integrated Services of the Marine Geoscience Data System and the Geoinformatics for Geochemistry Program  

Microsoft Academic Search

Development and operation of digital data collections are needed across all areas of the earth and ocean sciences to ensure access and preservation of data sets collected in support of earth and ocean sciences in order to maximize the return on research investments, while enabling verification of research results and contributing to new science initiatives. This is particularly true for

K. A. Lehnert; S. M. Carbotte; V. Ferrini; R. A. Arko; S. Chan; W. B. Ryan

2010-01-01

330

Earth: Earth Science and Health  

NASA Technical Reports Server (NTRS)

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.

Maynard, Nancy G.

2001-01-01

331

Earth materials and earth dynamics  

SciTech Connect

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).

Bennett, K; Shankland, T. [and others

2000-11-01

332

Information Technology Infusion Case Study: Integrating Google Earth(Trademark) into the A-Train Data Depot  

NASA Technical Reports Server (NTRS)

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 .

Smith, Peter; Kempler, Steven; Leptoukh, Gregory; Chen, Aijun

2010-01-01

333

Effects of rare-earth concentration and heat-treatment on the structural and luminescence properties of europium-doped zirconia sol gel planar waveguides  

NASA Astrophysics Data System (ADS)

Sol-gel zirconia films doped with Eu 3+ concentrations ranging from 0.2% to 10%, were prepared by dip-coating a solution of the starting precursor, zirconium n-propoxide, ethanol, methanol, water, acetic acid and europium nitrate on glass and SiO 2/Si wafer substrates. The ZrO 2 sol thus synthesized remains stable for several months. Structural characterization of the zirconia films was performed using Waveguide Raman Spectroscopy. These films present an amorphous phase up to an annealing temperature of 400 °C. Above 400 °C the matrix evolves towards a metastable tetragonal phase. This transformation was found to depend on the concentration of Eu 3+ ions. Indeed, while for samples doped with 0.2% Eu 3+ this transformation occurs around 450 °C, in the case of 10% of Eu 3+ ions, the transition is pushed off to 500 °C. The optical losses of these waveguides were found to be about 0.3 dB cm -1 for samples annealed at 400 °C. The surfaces of the films were characterized using Atomic Force Microscopy and the roughness was measured. The Eu-doped films were investigated using Waveguide Photoluminescence Spectroscopy. The dynamical behaviour of the Eu 3+ emissions indicated that concentration quenching effect is not observed even when the matrix is doped up to 10%.

Ehrhart, G.; Bouazaoui, M.; Capoen, B.; Ferreiro, V.; Mahiou, R.; Robbe, O.; Turrell, S.

2007-08-01

334

Large research infrastructure for Earth-Ocean Science: Challenges of multidisciplinary integration across hardware, software, and people networks  

NASA Astrophysics Data System (ADS)

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

Best, M.; Barnes, C. R.; Johnson, F.; Pautet, L.; Pirenne, B.; Founding Scientists Of Neptune Canada

2010-12-01

335

June 2004 / Vol. 54 No. 6 BioScience 547 Earth systems science--the integrated analysis of  

E-print Network

. A few years earlier, the introduction of the now famous at- mospheric "Keeling curve" for carbon dioxide progressively changing Earth's total atmosphere (Keeling et al.1976).Atmospheric scientists had recently

Hansen, Andrew J.

336

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

Microsoft Academic Search

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

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

337

Performance of an Integrated Voice\\/Data System in Nonuniform Traffic Low Earth-Orbit Satellite Communication Systems  

Microsoft Academic Search

In some recent studies, the use of low Earth-orbit satellites in various applications is considered. In all of these studies, uniform distribution of traffic load is assumed. In this paper, the performance of a low Earth-orbit satellite communication system which is designed to service to two kinds of users; i.e., voice users and data users is estimated. The distribution of

Abbas Jamalipour; Masaaki Katayama; Takaya Yamazato; Akira Ogawa

1995-01-01

338

Intense red-emitting multi-rare-earth doped nanoparticles of YVO4 for spectrum conversion towards improved energy harvesting by solar cells  

NASA Astrophysics Data System (ADS)

Yttrium vanadate nano-particles doped with single and multi ions (Sm3+, Eu3+, Bi3+) have been successfully synthesized at room temperature by optimized co-precipitation method. Doped orthovanadate forms monophasic nanocrystals in the 10-50 nm size range. Photoluminescence (PL) excitation shows broad band in the range 250-350 nm due to vanadate absorption and sharp peaks in the range of 390-470 nm due to f-f transitions of Sm3+/Eu3+ and emission in intense red/orange (614, 645, 699 nm). The nanoparticles can efficiently convert UV and blue photons (250-470 nm) to intense red and orange light that can be harnessed by both Si and dye sensitized solar cells for photovoltaic conversion. PL and time-resolved decay suggest that excitation and charge transfer between host, dopant and co-dopants play a profound role in the photophysical processes of multi-ion doped yttrium vanadate nanophosphor. Thin films of such nanophosphor exhibit 80-90% transparency in the visible range. Nanophosphor films convert UV to visible leading to better photon harvesting by solar cells.

Kumar, Vineet; Khan, A. F.; Chawla, Santa

2013-09-01

339

Simultaneous pulse amplification and compression in all-fiber-integrated pre-chirped large-mode-area Er-doped fiber amplifier.  

PubMed

A large-mode-area Erbium-doped fiber amplifier (LMA-EDFA) based all-fiber-integrated amplified compressor with ultrashort length of 5.37 m and ultralow pumping power (260 mW) is proposed. The LMAEDFA suppresses nonlinear soliton-self-frequency-shift effect happened during femtosecond pulse amplification, in which the fiber laser pulse is reshaped to a low-pedestal hyperbolic-second shape with nearly 100% energy confinement. The pre-chirped amplification from 0.96 to 104 mW and the simultaneous compression of a passively mode-locked fiber laser pulse from 300 to 56 fs is demonstrated. The input pulse energy of 24 pJ is amplified up to 2.6 nJ with shortened pulsewidth of 56 fs and peak power as high as 46 kW. PMID:19532537

Lin, Gong-Ru; Lin, Ying-Tsung; Lee, Chao-Kuei

2007-03-19

340

Long-lasting phosphorescence in rare earth doped CaO-MgO-B2O3-SiO2 glass  

NASA Astrophysics Data System (ADS)

CaO-MgO-B2O3-SiO2 glass co-doped with Eu2+, Dy3+ was prepared, which showed the Long lasting phosphorescence. The luminescent properties of this photoluminescence glass had been studied systematically. The main emission peaking at 476nm was ascribed to the 4f5d-->4f transition of Eu2+ in glass matrix. The optical absorption spectra of the samples fabricated under the ambient and reducing atmospheres were measured separately. The sample fabricated in the ambient atmospheres was transparent in wavelength region from 340nm to 1?m. While the samples fabricated in the reducing atmosphere a strong absorption band was observed from 350 to 450nm, and the peak was at the 375nm. This band could be assigned to the absorption of Eu2+ ions. The excitation spectra of the sample fabricated in the reducing atmosphere was measured. A strong peak at 396nm and a weak peak at 439nm were observed. They were ascribed to the transitions of Eu2+ ions. The results were conformed to the conclusion of the absorption spectrum. The afterglow decay process could be divided into two stages. One is an instant attenuation, and the other is a slow. Incorporation of rare ions Eu2+ and Dy3+ into glass matrix could largely change the long afterglow properties of the glass. The analytical results indicated that the co-doped Dy3+ ions acted as hole-trap levels and captured the free holes. It resulted in the property of long lasting phosphorescence of CaO-MgO-B2O3-SiO2 glass co-doped with Eu2+, Dy3+.

Yang, Zhiping; Liu, Chong; Feng, Jianwei; Yang, Yong; Li, Xingmin

2005-01-01

341

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)

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.

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

2013-07-01

342

X-ray line broadening analysis and optical studies of surfactant EDTA assisted rare earth ion cerium doped ZnS nanocrystals.  

NASA Astrophysics Data System (ADS)

We report a simple chemical precipitation method for the synthesis of EDTA capped cerium doped ZnS nanocrystals with an average size of around 2.88 nm. X-ray diffraction results revealed that the products were crystalline with cubic phase. Crystallite size and strain were estimated by Williamson-Hall (W-H) plots drawn using x-ray diffraction data. Compared with uncapped products, 5% of EDTA capped ZnS shows enhanced PL intensity ratio and suggesting a new class of luminescent material for the fabrication of optoelectronic devices.

Cholan, S.; Shanmugam, N.; Kannadasan, N.; Sathishkumar, K.; Viruthagiri, G.

2014-04-01

343

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

344

Correlation of structural distortion with magnetic properties in electron-doped Ca0.9R0.1MnO3 perovskites (R=rare-earth)  

NASA Astrophysics Data System (ADS)

A series of electron-doped orthorhombic-perovskite manganites Ca0.9R0.1MnO3 (R =La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Yb) are synthesized for a systematic study of their crystal structure and magnetic properties. The structural distortions, in terms of the average Mn-O-Mn bond angle ?Mn-O-Mn and Mn-O bond length dMn-O, are characterized as a function of the A-site ionic size. Two degenerate vibration modes Q2 and Q3 are used for describing the bond length splitting and the evolution of the octahedral-site distortion. With R3+ doping, the magnetization increases markedly at low temperatures, which can be attributed to the formation of ferromagnetic clusters in the antiferromagnetic matrix. Both low temperature magnetization and paramagnetic susceptibility vary with the radius of R3+ ion and enhanced ferromagnetic domain is found in Ca0.9Ho0.1MnO3. The Néel temperature TN, varying from 100 to 116 K, is strongly dependent on the crystal structural distortions and can be well described as functions of three structural parameters ?Mn-O-Mn, dMn-O, and A-site cation size variance ?2. The best size matching between Dy3+ and Ca2+ leads to the highest TN in Ca0.9Dy0.1MnO3.

Wang, Yang; Sui, Yu; Wang, Xianjie; Su, Wenhui; Liu, Xiaoyang

2010-09-01

345

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)

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.

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

2007-12-01

346

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.

2012-05-31

347

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

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.

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

348

BaY{sub 2}F{sub 8} single crystals doped with rare-earth ions as promising up-conversion media for UV and VUV lasers  

SciTech Connect

BaY{sub 2}F{sub 8} crystals are studied as promising active media for UV and VUV lasers. The up-conversion pumping of rare-earth activators is proposed to solve problems related to the solarisation of the medium and the selection of pump sources. The technology of growing oriented BaY{sub 2}F{sub 8} single crystals is developed and the influence of the crystal orientation on the growth rate and quality of single crystals is determined. (active media)

Pushkar', A A; Uvarova, T V [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Molchanov, V N [A.V. Shubnikov Institute of Crystallography, Russian Academy of Sciences, Moscow, Russian Federaion (Russian Federation)

2008-04-30

349

UNIVERSITY of CALIFORNIA EFFECT OF BISMUTH DOPING ON THE MAGNETIC PROPERTIES  

E-print Network

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

Belanger, David P.

350

ac susceptibility studies in Fe doped La0.65Ca0.35Mn1-xFexO3: Rare earth manganites  

NASA Astrophysics Data System (ADS)

The effects of Fe substitution on Mn sites in the colossal magnetoresistive compounds La0.65Ca0.35Mn1-xFexO3 with 0.00?x?0.10 have been studied. A careful study in the magnetic properties has been carried out by the measurement of magnetic ac susceptibility. The temperature range of colossal magnetoresistance (CMR) is greatly broadened with the addition of Fe. Substitution of Fe induces a gradual transition from a metallic ferromagnetic with a high Curie temperature (Tc=270 K) to a ferromagnetic insulator with low Tc=79 K. Increased spin disorder and decrease of Tc with increasing Fe content are evident. The variations in the critical temperature Tc and magnetic moment show a rapid change at about 4%-5% Fe. The effect of Fe is seen to be consistent with the disruption of the Mn-Mn exchange possibly due to the formation of magnetic clusters. An extraordinary behavior in the out of phase part (??) of ac susceptibility, characterized by double bump (shoulder), was observed around x=0.01 and 0.02. The shoulder in ?? disappears at x?0.04 Fe concentration. With increasing Fe concentration the ?? peak shift to Tdoping. Doping with Fe bypasses the usually dominant lattice effects, but depopulates the hopping electrons and thus weakens the double exchange. The results were explained in terms of the formation of magnetic clusters of Fe ions.

Shah, Wiqar Hussain; Hasanain, S. K.

2010-12-01

351

A model of recent vertical movements of the earth's surface in Lithuania: integration of geodetic levelling data and geological parameters  

NASA Astrophysics Data System (ADS)

The precise geodetic levelling reveals the recent activity of the vertical movements of the earth's crust. However, the main shortcoming of the levelling networks is scarceness of the measurement tracks that cannot be compensated for by a high density of the levelling sites within the tracks. The pattern and trends of vertical movements between the measured lines remain unknown. A special approach has been developed to allow prediction of vertical movements within the test grounds. It is based on the multicomponent statistical correlation of the levelling data with the significant geological parameters. The correlations between among parameters were derived separately for each particular test ground and then combined into one common model. It allowed compilation of a rather detailed map of vertical movements in Lithuania during the past 30-40 years. The rate of vertical movements of the earth's surface, obtained from the geodetic levelling, varies from -2.7 mm to 3.5 mm/y. The closest correlation of the recent movements was identified for the topography and the sub-Quaternary surface. It indicates that the major morphological features of Lithuania have a tectonic background. Furthermore, a close correlation was obtained with the gravity and in some parts with the magnetic fields which reflect the deep structure of the earth's crust. A close correlation suggests that the heterogeneity of the crust is important for the distribution of its vertical movements. The application of the close correlation with the geoparameters allowed a considerable improvement of the map of the vertical movements in Lithuania.

Zakarevi?ius, Algimantas; Šliaupa, Saulius; Anik?nien?, Asta; D?nas, Žydr?nas; Šliaupien?, Rasa

2008-01-01

352

Electron thermalization and trapping rates in pure and doped alkali and alkaline-earth iodide crystals studied by picosecond optical absorption  

NASA Astrophysics Data System (ADS)

Although light continues to be emitted from insulating crystals used as scintillators over a period of nanoseconds to microseconds after stopping of an energetic particle, much of what determines the nonlinearity of response goes on in the first picoseconds. On this time scale, free carriers and excitons are at high density near the track core and thus are subject to nonlinear quenching. The hot (free) electrons eventually cool to low enough energy that trapping on holes, dopants, or defects can commence. In the track environment, spatial distributions of trapped carriers determined on the picosecond time scale can influence the proportionality between light yield and the initial particle energy throughout the whole light pulse. Picosecond spectroscopy of optical absorption induced by a short pulse of above-gap excitation provides a useful window on what occurs during the crucial early evolution of excited populations. The laser excitation can be tuned to excite carriers that are initially very hot (˜3 eV) relative to the band edges, or that are almost thermalized (˜0.1 eV excess energy) at the outset. Undoped and doped samples of NaI:Tl(0%, 0.1%), CsI:Tl(0%, 0.01%, 0.04%, 0.3%), and SrI2:Eu(0%, 0.2%, 0.5%, 3%) are studied in this work.

Ucer, K. B.; Bizarri, G.; Burger, A.; Gektin, A.; Trefilova, L.; Williams, R. T.

2014-04-01

353

Incubational domain characterization in lightly doped ceria  

SciTech Connect

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.

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

354

Design of broadband erbium-doped fiber amplifier using very high-speed integrated circuit hardware description language for next-generation optical network  

NASA Astrophysics Data System (ADS)

We mainly concentrate on the problem of gain broadening and flattening of erbium-doped fiber amplifier (EDFA) using dual forward-pumping configuration in which we use pumping both at 980 and 1480 nm wavelengths. The gain cascading of two EDFAs pumped separately at 980 and 1480 nm combines the advantage of high gain characteristics of 980 nm pumping and broad bandwidth characteristics of 1480 nm pumping. The use of increased number of channels in the present dense wavelength division multiplexing (DWDM) optical network requires a flat gain spectrum across the whole usable bandwidth. The use of very high-speed integrated circuit hardware description language (VHDL-AMS) in lightwave system modeling has been explored. Its application in designing wideband EDFA has not been reported thus far. This work facilitates to design broadband EDFA operating in both the C-band and L-band regions with VHDL-AMS. The amplifier design is made of a dual stage, copumped at 980 and 1480 nm, which delivers an average output power of -16 dBm over the entire 3-dB bandwidth of 80 nm.

Goel, Aditya; Mishra, Ravi Shankar

2011-01-01

355

Rally around Earth Month.  

ERIC Educational Resources Information Center

Proposes that schools declare April as "Earth Month." Explains how to get started and ways to get students excited. Describes environmental lessons and integrated activities. Provides the addresses of six sources for environmental education resources.(PR)

Hutchinson, Elaine

1993-01-01

356

Large research infrastructure for Earth-Ocean Science: Challenges of multidisciplinary integration across hardware, software, and people networks  

Microsoft Academic Search

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

M. Best; C. R. Barnes; F. Johnson; L. Pautet; B. Pirenne

2010-01-01

357

Large subsea observatory for earth-ocean science: Challenges of multidisciplinary integration across hardware, software, and people networks  

Microsoft Academic Search

NEPTUNE Canada has installed and is operating a regional cabled ocean observatory from the coast 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

C. R. Barnes; M. M. R. Best; F. R. Johnson; B. Pirenne

2010-01-01

358

Three-dimensional cavity quantum electrodynamics with a rare-earth spin ensemble  

NASA Astrophysics Data System (ADS)

We present cavity QED experiments with an Er3+:Y2SiO5 crystal magnetically coupled to a three-dimensional (3D) cylindrical sapphire loaded copper resonator. Such waveguide cavities are promising for the realization of a superconducting quantum processor. Here, we demonstrate the coherent integration of a rare-earth spin ensemble with the 3D architecture. The collective coupling strength of the Er3+ spins to the 3D cavity is 21 MHz. The cylindrical sapphire loaded resonator allowed us to explore the anisotropic collective coupling between the rare-earth doped crystal and the cavity. This work shows the potential of spin doped solids in 3D quantum circuits for application as microwave quantum memories as well as for prospective microwave to optical interfaces.

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

2014-09-01

359

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

E-print Network

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.

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

360

Erbium-doped GaN epilayers synthesized by metal-organic chemical vapor deposition  

E-print Network

. A majority of the research done for rare-earth doping has been devoted to the element Er,1­16 since one.1063/1.2361196 Incorporation of rare-earth atoms into a semiconductor host has received much attention due to the potential appli- cations of rare-earth-doped materials as efficient optical am- plifiers and light emitters

Jiang, Hongxing

361

Development of response models for the Earth Radiation Budget Experiment (ERBE) sensors. Part 2: Analysis of the ERBE integrating sphere ground calibration  

NASA Technical Reports Server (NTRS)

An explicit solution of the spectral radiance leaving an arbitrary point on the wall of a spherical cavity with diffuse reflectivity is obtained. The solution is applicable to spheres with an arbitrary number of openings of any size and shape, an arbitrary number of light sources with possible non-diffuse characteristics, a non-uniform sphere wall temperature distribution, non-uniform and non-diffuse sphere wall emissivity and non-uniform but diffuse sphere wall spectral reflectivity. A general measurement equation describing the output of a sensor with a given field of view, angular and spectral response measuring the sphere output is obtained. The results are applied to the Earth Radiation Budget Experiment (ERBE) integrating sphere. The sphere wall radiance uniformity, loading effects and non-uniform wall temperature effects are investigated. It is shown that using appropriate interpretation and processing, a high-accuracy short-wave calibration of the ERBE sensors can be achieved.

Halyo, Nesim; Taylor, Deborah B.

1987-01-01

362

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)

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.

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

363

Peru Water Resources: Integrating NASA Earth Observations into Water Resource Planning and Management in Perus La Libertad Region  

NASA Technical Reports Server (NTRS)

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.

Padgett-Vasquez, Steve; Steentofte, Catherine; Holbrook, Abigail

2014-01-01

364

Future intelligent Earth observing satellites  

Microsoft Academic Search

This paper presents a simulated architecture of an envisioned future intelligent Earth observing satellite system (FIEOS). The proposed system is a space-based architecture for dynamic and comprehensive on-board integration of Earth observing sensors, data processors and communication systems. It is intended to enable simultaneous, global measurements and timely analyses of Earth's environment for a variety of users. This paper also

Guoqing Zhou

2003-01-01

365

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)

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).

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

2014-10-01

366

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

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

367

Earth's Three  

E-print Network

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...

Hacker, Randi

2010-11-17

368

Earth's Atmosphere  

NSDL National Science Digital Library

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.

369

Earth Sciences Environmental Earth Sciences,  

E-print Network

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 Sciences offers BSc Honours degrees in Geology and Environmental Earth Sciences, and your degree choice

Brierley, Andrew

370

Earth Sciences Environmental Earth Sciences,  

E-print Network

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

Brierley, Andrew

371

A New Northern Eurasia Earth Science Partnership Initiative (NEESPI): Science Plan of Integrated Approach to Regional Climate and Environment Change Studies  

NASA Astrophysics Data System (ADS)

The Northern Eurasia Earth Science Partnership Initiative (NEESPI) is an international large-scale, integrated, regional program of research focusing on the area of Northern Eurasia initiated by NASA and Russian Academy of Sciences. A brief introduction of the NEESPI Science Plan (SP) will be presented. While extensive and diverse, Northern Eurasia has common (and unique) features, the studying of which in a corroborated fashion under the NEESPI umbrella will produce synergetic effects. SP specifically addresses the reasons to look on the region as a "single" piece: transitional economies and land use (the legacy of the former USSR), geographical features (largest landmass in the extratropics mostly isolated from humid air masses), one of the world highest sensitivities to climatic and environmental changes with feedbacks of global concern and extensive and fluent transitional zones between ecosystems. The major NEESPI science question is: How do Northern Eurasia's terrestrial ecosystems dynamics interact with and alter the biosphere, atmosphere, and hydrosphere of the Earth? These dynamics have several facets: Biogeochemical Cycles, Surface Energy and Water Cycles, and Interactions with Human Society, each of which have to be studied in their interactions and complexity. Studying of Ecosystem-Climate Interactions mechanisms and Modeling component became a centerpiece of the SP. These studies can be conducted within a suite of models that are considered as a major instrument to assess our predictive capabilities of environmental changes and ecosystem sustainability in Northern Eurasia to support numerous applications and decision making. The creation of such a suite of models and providing it with an appropriate input data stream emerges as a focus of the Initiative. Remote sensing has an important role in the NEESPI science program, providing up to date and historical, spatially explicit information to inventory and quantify changes in the land surface and in the coastal zone for use in process and modeling studies. Social aspects of the NEESPI SP include the Education and land use components.

Groisman, P. Y.; Bartalev, S. A.

2004-12-01

372

The Quickest, Lowest-cost Lunar Resource Assessment Program: Integrated High-tech Earth-based Astronomy  

NASA Technical Reports Server (NTRS)

Science and technology applications for the Moon have not fully kept pace with technical advancements in sensor development and analytical information extraction capabilities. Appropriate unanswered questions for the Moon abound, but until recently there has been little motivation to link sophisticated technical capabilities with specific measurement and analysis projects. Over the last decade enormous technical progress has been made in the development of (1) CCD photometric array detectors; (2) visible to near-infrared imaging spectrometers; (3)infrared spectroscopy; (4) high-resolution dual-polarization radar imaging at 3.5, 12, and 70 cm; and equally important (5) data analysis and information extraction techniques using compact powerful computers. Parts of each of these have been tested separately, but there has been no programmatic effort to develop and optimize instruments to meet lunar science and resource assessment needs (e.g., specific wavelength range, resolution, etc.) nor to coordinate activities so that the symbiotic relation between different kinds of data can be fully realized. No single type of remotely acquired data completely characterizes the lunar environment, but there has been little opportunity for integration of diverse advanced sensor data for the Moon. Two examples of technology concepts for lunar measurements are given. Using VIS/near-IR spectroscopy, the mineral composition of surface material can be derived from visible and near-infrared radiation reflected from the surface. The surface and subsurface scattering properties of the Moon can be analyzed using radar backscattering imaging.

Pieters, Carle M.

1992-01-01

373

Earth\\'s Surface  

NSDL National Science Digital Library

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 ...

Mathis, Ms.

2008-01-11

374

Doping droops.  

PubMed

Drug abuse is a major concern in the athletic world. The misconception among athletes and their coaches is that when an athlete breaks a record it is due to some "magic ingredient" and not because of training, hard work, mental attitude and championship performance. The personal motivation to win in competitive sports has been intensified by national, political, professional and economic incentives. Under this increased pressure athletes have turned to finding this "magic ingredient". Athlete turns to mechanical (exercise, massage), nutritional (vitamins, minerals), pharmacological (medicines) or gene therapies to have an edge over other players. The World Anti-Doping Agency (WADA) has already asked scientists to help find ways to prevent gene therapy from becoming the newest form of doping. The safety of the life of athletes is compromised with all forms of doping techniques, be it a side effect of a drug or a new technique of gene doping. PMID:18175655

Chaturvedi, Aditi; Chaturvedi, Harish; Kalra, Juhi; Kalra, Sudhanshu

2007-01-01

375

Reducing Loss of Life and Property from Disasters: A Societal Benefit Area of the Strategic Plan for U.S. Integrated Earth Observation System (IEOS)  

USGS Publications Warehouse

Natural and technological disasters, such as hurricanes and other extreme weather events, earthquakes, volcanic eruptions, landslides and debris flows, wildland and urban-interface fires, floods, oil spills, and space-weather storms, impose a significant burden on society. Throughout the United States, disasters inflict many injuries and deaths, and cost the nation $20 billion each year (SDR, 2003). Disasters in other countries can affect U.S. assets and interests overseas (e.g. the eruption of Mt. Pinatubo in the Philippines, which effectively destroyed Clark Air Force Base). Also, because they have a disproportionate impact on developing countries, disasters are major barriers to sustainable development. Improving our ability to assess, predict, monitor, and respond to hazardous events is a key factor in reducing the occurrence and severity of disasters, and relies heavily on the use of information from well-designed and integrated Earth observation systems. To fully realize the benefits gained from the observation systems, the information derived must be disseminated through effective warning systems and networks, with products tailored to the needs of the end users and the general public.

Helz, Rosalind L.; Gaynor, John E.

2007-01-01

376

Integration of separation and photocatalysis using an inorganic membrane modified with Si-doped TiO 2 for water purification  

Microsoft Academic Search

An unsymmetrical inorganic membrane with Si-doped TiO2 layers was fabricated for the purpose of realizing filtration and photocatalysis in a single device in water purification process. Tetra-n-butyl titanate [Ti(OC4H9)4, TBOT] and tetraethyl orthosilicate [Si(OC2H5)4, TEOS] were used as precursors of TiO2 and Si element source, and Si-doped TiO2 photocatalytic layer was coated on a commercial Al2O3 membrane by sol–gel technique.

Ning Ma; Xie Quan; Yaobin Zhang; Shuo Chen; Huimin Zhao

2009-01-01

377

Process characterization of a novel conformal FinFET doping  

NASA Astrophysics Data System (ADS)

Process characterization of a novel plasma based conformai doping technique was conducted for arsenic dopant in terms of silicon amorphization, fin integrity, doping conformality, sheet resistance and main effect of doping process parameters. Doping conformality, the ratio of doping at fin sidewall and top, was characterized by cross-section transmission electron spectroscopy (XTEM) and top-down secondary ion mass spectroscopy (SIMS) on fin structures. The residual post-anneal damage was also evaluated by XTEM. Sheet resistance (Rs) was used for studying dopant activation. The effect of main doping process parameters on thermal wave (TW), sheet resistance (Rs) and silicon fin amorphization was also studied.

Han, K.; Tang, S.; Rockwell, T.; Godet, L.; Persing, H.; Distaso, D.; Campbell, C.; Salimian, S.

2012-11-01

378

Design of broadband erbium-doped fiber amplifier using very high-speed integrated circuit hardware description language for next-generation optical network  

Microsoft Academic Search

We mainly concentrate on the problem of gain broadening and flattening of erbium-doped fiber amplifier (EDFA) using dual forward-pumping configuration in which we use pumping both at 980 and 1480 nm wavelengths. The gain cascading of two EDFAs pumped separately at 980 and 1480 nm combines the advantage of high gain characteristics of 980 nm pumping and broad bandwidth characteristics

Aditya Goel; Ravi Shankar Mishra

2011-01-01

379

ERBIUM-DOPED WET OXIDES OF AlGaAs AND InAlP ON GaAs SUBSTRATES FOR OPTOELECTRONIC INTEGRATION  

E-print Network

-implantation method (as demonstrated by a ~2-3X increase in intensity and 7-8X increase in fluorescence lifetime distributed pump power along Er-doped waveguides, and better noise control compared to conventional end size and cost, paving the way for a possible future revolution in more agile optical networks, compact

380

Google Earth  

NSDL National Science Digital Library

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.

2009-01-01

381

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)

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.

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

382

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."

383

Earth Changes  

NSDL National Science Digital Library

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).

1998-01-01

384

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.

385

Earth Observing System AM1 mission to Earth  

Microsoft Academic Search

In 1998, NASA launches EOS-AMI, the first of a series of the Earth Observing System (EOS) satellites. EOS will monitor the evolution of the state of the earth for 18 years, starting with the morning observations of EOS-AM1 (10:30 a.m. equatorial crossing time). An integrated view of the earth, as planned by EOS, is needed to study the interchange of

Yoram J. Kaufman; David D. Herring; K. Jon Ranson; G. James Collatz

1998-01-01

386

All-organic polymer-dispersed liquid crystal light-valves integrated with electroactive anthraquinone-2-sulfonate-doped polypyrrole thin films as driving electrodes  

Microsoft Academic Search

All-organic PDLC (polymer-dispersed liquid crystal) light-valves using all-polymer conductive substrates containing thin films of polypyrrole doped with anthraquinone-2-sulfonate (AQSA?) as the driving electrodes were fabricated in this study. The all-polymer conductive substrates were prepared under ambient conditions by in situ depositing polypyrrole thin films on blank flexible poly(ethylene terephthalate), or PET, substrates from aqueous media in which oxidative polymerization of

Pen-Cheng Wang; Jing-Yu Yu; Kuan-Hsun Li

2011-01-01

387

Local order around rare earth ions during the devitrification of oxyfluoride glasses  

E-print Network

Local order around rare earth ions during the devitrification of oxyfluoride glasses Maurício A. P EXAFS measurements were performed on rare earth doped fluorosilicate and fluoroborate glasses and glass. Molecular dynamics simulations of the devitrification process of a lead fluoride glass doped with Er3+ ions

Boyer, Edmond

388

Gene doping.  

PubMed

Together with the rapidly increasing knowledge on genetic therapies as a promising new branch of regular medicine, the issue has arisen whether these techniques might be abused in the field of sports. Previous experiences have shown that drugs that are still in the experimental phases of research may find their way into the athletic world. Both the World Anti-Doping Agency (WADA) and the International Olympic Committee (IOC) have expressed concerns about this possibility. As a result, the method of gene doping has been included in the list of prohibited classes of substances and prohibited methods. This review addresses the possible ways in which knowledge gained in the field of genetic therapies may be misused in elite sports. Many genes are readily available which may potentially have an effect on athletic performance. The sporting world will eventually be faced with the phenomena of gene doping to improve athletic performance. A combination of developing detection methods based on gene arrays or proteomics and a clear education program on the associated risks seems to be the most promising preventive method to counteract the possible application of gene doping. PMID:16572366

Haisma, H J; de Hon, O

2006-04-01

389

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.

2007-04-19

390

Earth's Interior  

NSDL National Science Digital Library

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.

Louie, John

391

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.

392

Strategy for earth explorers in global earth sciences  

NASA Technical Reports Server (NTRS)

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.

1988-01-01

393

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.

394

Earth\\'s Mass Variability  

E-print Network

The perturbation of the Earth caused by variability of mass of Earth as additional reason with gravity of celestial bodies and shape of the Earth. The Earth eating and collecting matters from space and loss or eject matters to space through its flying in the space around the Sun. The source of the rising in the global sea level is not closed in global warming and icebergs, but the outer space is the additional important source for this rising. The Earth eats waters from space in unknown mechanism. The mass of the Earth become greater in November i.e. before transit apoapsis two months, and become latter in February i.e. after transit apoapsis to two months.

Mawad, Ramy

2014-01-01

395

Determination of monomethylhydrazine with a high-throughput, all-fiber near-infrared spectrometer based on an integrated acoustooptic tunable filter and an erbium-doped fiber amplifier.  

PubMed

A novel integrated acoustooptic tunable filter (IAOTF) has been developed. This tunable filter is based on the Bragg interactions between waveguide and surface acoustic waves. Compared to (bulk) AOTF, its advantage include all-fiber construction, smaller size, narrower spectral resolution (1.7 nm), higher diffraction efficiency (37%), and lower rf power requirement (150 mW). A relatively narrow spectral tuning range (about 80 nm) is the only drawback for this integrated tunable filter. However, this disadvantage was overcome by judiciously using the filter for measurements in which its tuning range is coincident with the light source and also with absorption bands of analytes. In fact, an all-fiber, compact, high-throughput near-infrared spectrophotometer has been successfully constructed by synergistic use of this integrated AOTF and the erbium-doped fiber amplifier (EDFA), which has been shown to provide high intensity and wide spectral band-width in the near-infrared region from 1500 to 1600 nm. This spectral region is particularly useful for the determination of samples which have O-H and/or N-H groups. The all-fiber nature, compactness, high throughput, and high sensitivity of this spectrophotometer make it particularly suitable for on-line and real-time detection of trace gases in hostile environments, including leak detection of monomethylhydrazine (at a limit of detection of 191 ppm), which is often used as the hypergolic propellant for the space shuttle thruster systems. PMID:9105182

Tran, C D; Gao, G H

1997-04-01

396

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)

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

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

2009-12-01

397

Google Earth Engine  

NASA Astrophysics Data System (ADS)

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.

Gorelick, Noel

2013-04-01

398

Google Earth Engine  

NASA Astrophysics Data System (ADS)

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.

Gorelick, N.

2012-12-01

399

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

E-print Network

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

Pandey, Ravi

400

Earth Impact  

NSDL National Science Digital Library

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.

Integrated Teaching And Learning Program

401

Rainbow Earth.  

ERIC Educational Resources Information Center

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…

Arizona State Dept. of Library and Archives, Phoenix.

402

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

NASA Astrophysics Data System (ADS)

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.

Dorosz, Dominik; Zmojda, Jacek; Kochanowicz, Marcin

2014-07-01

403

Selecting ensembles for rare earth quantum computation  

E-print Network

We discuss the issues surrounding the implementation of quantum computation in rare-earth-ion doped solids. We describe a practical scheme for two qubit gate operations which utilise experimentally available interactions between the qubits. Possibilities for a scalable quantum computer are discussed.

J. J. Longdell M. J. Sellars

2003-10-16

404

Challenges and perspectives in anti-doping testing.  

PubMed

In less than 10 years after the implementation of the World Anti-Doping Code and of the International Standard for Laboratories and its related Technical Documents, the analysis of human samples for the purpose of anti-doping testing has undergone a noticeable evolution. The research programs developed by the anti-doping organizations, and in particular the World Anti-Doping Agency (WADA), have created an unprecedented momentum in anti-doping science to strengthen the existing analytical methods, as well as to support the development and implementation of new and more sophisticated methodologies by the WADA-accredited laboratories. The integration of technical novelties into the analytical menus has been stimulated by the never-ending challenges posed by the adoption of more complex doping regimens by some athletes and their entourage. This increased sophistication of doping practices has also been reflected in the addition of new doping substances or methods on the WADA Prohibited Substances and Methods List. The integration of new anti-doping scientific paradigms with the development of the Athlete Biological Passport or the foreseen implementation of genomic- and proteomic-based tests constantly reshapes the environment of anti-doping analysis. This article provides a multiangle perspective on some of the key analytical challenges that anti-doping analytical science will face in 2012 and beyond. PMID:22831484

Schamasch, Patrick; Rabin, Olivier

2012-07-01

405

Planet Earth  

NSDL National Science Digital Library

How does the Earth work? What is its relationship to the other planets? These are but a few important questions answered by this creative instructional series created by WQED in Pittsburgh, in association with the National Academy of Sciences. The series was designed to present information about "our solar system and Earth's oceans, climate, and mineral and energy sources." The Annenberg Media group has placed this entire series online, and visitors can view all seven installments here. The programs include "The Climate Puzzle", "Gifts from the Earth", and "The Solar Sea". Teachers will note that the site also contains links to other educational resources, reviews, and related resources from the Annenberg Media organization.

1986-01-01

406

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.

407

Discover Earth  

NASA Technical Reports Server (NTRS)

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.

Steele, Colleen

1996-01-01

408

Earth's Surface  

NSDL National Science Digital Library

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.

Science, Houghton M.

409

Earth Systems  

NSDL National Science Digital Library

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.

Science, Houghton M.

410

Discover Earth  

NASA Technical Reports Server (NTRS)

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.

1997-01-01