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1

Plasma synthesis of rare earth doped integrated optical waveguides  

SciTech Connect

We describe a novel means for the production of optically active planar waveguides. The makes use of a low energy plasma deposition. Cathodic-arc-produced metal plasmas the metallic components of the films and gases are added to form compound films. Here we discuss the synthesis of Al{sub 2{minus}x}ER{sub x}O{sub 3} thin films. The erbium concentration (x) can vary from 0 to 100% and the thickness of the film can be from Angstroms to microns. In such material, at high active center concentration (x=l% to 20%), erbium ions give rise to room temperature 1.53{mu}m emission which has minimum loss in silica-based optical fibers. With this technique, multilayer integrated planar waveguide structures can be grown, such as Al{sub 2}O{sub 3}/Al{sub 2{minus}x}Er{sub x}O{sub 3}/Al{sub 2}O{sub 3}/Si, for example.

Raoux, S.; Anders, S.; Yu, K.M.; Brown, I.G. [Lawrence Berkeley Lab., CA (United States); Ivanov, I.C. [Charles Evans & Associates, Redwood City, CA (United States)

1995-03-01

2

Rare Earth Doped Confined Structures for Lasers and Amplifiers  

NASA Astrophysics Data System (ADS)

Rare-earth(RE) doped insulating materiais exhibit varieties of luminescent behavior with applications in solid-state physics, high energy physics, biophysics, photochemistry, medical sciences, and telecommunications, as well as in fundamental research. Recently the incorporation of trivalent rare-earth ions into waveguides has created a considerable upsurge of interest in the field of signal processing for telecommunications, based on the success of the very efficient erbium doped fiber amplifier (EDFA) for long haul transmissions together with the explosion of Internet. Wavelengths division multiplexing (WDM) is nowadays increasing the amount of channel information over a wide energy range in the low-loss region of silica fibers. However, to cover the 25 THz available window, new materiais are required, implying the use of new doping and amplifier structures. In the course of this research, new laser sources were obtained at various wavelengths, using up-conversion pumping schemes, for instance. Furthermore, the development of RE-doped integrated optics is now considered for compactness and low-cost devices, offering a new challenge for RE-doped materiais and luminescence processes. Finally, in a promising development, extremely miniaturized devices make possible subwavelength optics that capitalize on the dynamics of a very small number of photons, which can be analyzed for example in the new RE-doped optical microcavitàes and nanostructures.

Jacquier, B.; Bigot, L.; Guy, S.; Jurdyc, A. M.

3

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

4

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

5

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

6

Rare Earth Doped Confined Structures for Lasers and Amplifiers  

Microsoft Academic Search

Rare-earth(RE) doped insulating materiais exhibit varieties of luminescent behavior with applications in solid-state physics,\\u000a high energy physics, biophysics, photochemistry, medical sciences, and telecommunications, as well as in fundamental research.\\u000a Recently the incorporation of trivalent rare-earth ions into waveguides has created a considerable upsurge of interest in\\u000a the field of signal processing for telecommunications, based on the success of the very

B. Jacquier; L. Bigot; S. Guy; A. M. Jurdyc

7

Niobium phosphate glasses doped with rare earths  

NASA Astrophysics Data System (ADS)

Er- and Sm-doped sodium-niobium phosphate glasses have been produced by melting technique. Their optical and spectroscopic properties have been fully characterized. Fluorescence lifetimes of the metastable states of Er3+ and Sm3+ ions are long enough to make these glasses suitable to be used in optical amplification devices. Waveguides have been produced by diluted Ag+/Na+ ion exchange and their properties are also described.

Chen, B. J.; Brenci, Massimo; Pelli, Stefano; Righini, Giancarlo C.; Lipovskii, Andrey A.; Tagantsev, Dmitrii K.

2003-11-01

8

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

9

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

10

Torque Measurements on Rare-Earth Doped Yttrium Iron Garnet  

Microsoft Academic Search

This paper describes torque measurements made at 4.2 and 1.5°K on yttrium iron garnet crystals containing small rare-earth ion dopings kindly supplied by Dr. J. F. Dillon, Jr., and Dr. J. W. Nielson of the Bell Telephone Laboratories. Resonance measurements by Dillon (1959) showed that the giant anisotropy peaks observed in yttrium iron garnet at 4.2°K were due to the

R. F. Pearson; R. W. Cooper

1961-01-01

11

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

12

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.

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

1998-01-01

13

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

14

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

E-print Network

in a rare-earth-metal-ion-doped crystal Lars Rippe, Mattias Nilsson, and Stefan Kröll Department of Physics on optical interactions in rare-earth- metal-ion-doped crystals. The optical transition lines of the rare-earth-metal out in preparation for two-qubit gate operations in the rare-earth-metal-ion-doped crystals

Suter, Dieter

15

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. PMID:25429335

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

2014-01-01

16

Rare Earth Doped Yttrium Aluminum Garnet (YAG) 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 presents a spectral emittance model for films and cylinders of rare earth doped yttrium aluminum garnets. Good agreement between experimental and theoretical film spectral emittances was found for erbium and holmium aluminum garnets. Spectral emittances of films are sensitive to temperature differences across the film. For operating conditions of interest, the film emitter experiences a linear temperature variation whereas the cylinder emitter has a more advantageous uniform temperature. Emitter efficiency is also a sensitive function of temperature. For holminum aluminum garnet film the efficiency is 0.35 at 1446K but only 0.27 at 1270 K.

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

1999-01-01

17

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

18

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

NASA Astrophysics Data System (ADS)

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

Zhang, Lei; Liu, Chang

2015-02-01

19

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

20

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

21

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

22

Computer modelling of doped mixed metal fluorides and oxides for device applications: Rare earth, sodium and barium doped KYF 4  

NASA Astrophysics Data System (ADS)

The mixed metal fluorides and oxides have a range of important applications in optical and electronic devices. For example, rare earth doped LiCaAlF 6 is used in solid state lasers; and pure and doped LiNbO 3 is used in a wide range of optical and electronic applications. In attempting to develop new materials, two questions which arise include: which host lattices are most suitable, and which dopants will produce the required optical behaviour? This paper continues recent work designed to provide straightforward computational approaches to predict and assess properties of such materials, presenting the results of recent calculations on rare earth doping in KYF 4, as well as sodium and barium doping, which has been prompted by experimental work in this area.

Jackson, Robert A.; Maddock, Elizabeth M.; Valerio, Mario E. G.

2008-06-01

23

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

24

Mixedness determination of rare earth-doped ceramics  

NASA Astrophysics Data System (ADS)

The lack of chemical uniformity in a powder mixture, such as clustering of a minor component, can lead to deterioration of materials properties. A method to determine powder mixture quality is to correlate the chemical homogeneity of a multi-component mixture with its particle size distribution and mixing method. This is applicable to rare earth-doped ceramics, which require at least 1-2 nm dopant ion spacing to optimize optical properties. Mixedness simulations were conducted for random heterogeneous mixtures of Nd-doped LaF3 mixtures using the Concentric Shell Model of Mixedness (CSMM). Results indicate that when the host to dopant particle size ratio is 100, multi-scale concentration variance is optimized. In order to verify results from the model, experimental methods that probe a mixture at the micro, meso, and macro scales are needed. To directly compare CSMM results experimentally, an image processing method was developed to calculate variance profiles from electron images. An in-lens (IL) secondary electron image is subtracted from the corresponding Everhart-Thornley (ET) secondary electron image in a Field-Emission Scanning Electron Microscope (FESEM) to produce two phases and pores that can be quantified with 50 nm spatial resolution. A macro was developed to quickly analyze multi-scale compositional variance from these images. Results for a 50:50 mixture of NdF3 and LaF3 agree with the computational model. The method has proven to be applicable only for mixtures with major components and specific particle morphologies, but the macro is useful for any type of imaging that produces excellent phase contrast, such as confocal microscopy. Fluorescence spectroscopy was used as an indirect method to confirm computational results for Nd-doped LaF3 mixtures. Fluorescence lifetime can be used as a quantitative method to indirectly measure chemical homogeneity when the limits of electron microscopy have been reached. Fluorescence lifetime represents the compositional fluctuations of a dopant on the nanoscale while accounting for billions of particles in a fast, non-destructive manner. The significance of this study will show how small-scale fluctuations in homogeneity limit the optimization of optical properties, which can be improved by the proper selection of particle size and mixing method.

Czerepinski, Jennifer H.

25

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

PubMed Central

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 SnO2and also by the annealing temperatures. Doping led to chemical and micro-structural variations at the surface of the SnO2particles. Changes in the catalytic properties of the samples, such as selectivity toward ethylene, may be ascribed to different dopings and annealing temperatures.

2008-01-01

26

Origin of enhanced magnetization in rare earth doped multiferroic bismuth ferrite  

SciTech Connect

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

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

2014-02-21

27

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

SciTech Connect

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

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

1997-07-26

28

Growth and characterization of rare earths doped triglycine sulfate crystals  

Microsoft Academic Search

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

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

2006-01-01

29

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

30

Processing and electrical properties of alkaline earth-doped lanthanum gallate  

Microsoft Academic Search

Oxides exhibiting substantial oxygen ion conductivity are utilized in a number of high-temperature applications, including solid oxide fuel cells, oxygen separation membranes, membrane reactors, and oxygen sensors. Alkaline earth-doped lanthanum gallate powders were prepared by glycine\\/nitrate combustion synthesis. Compacts of powders synthesized under fuel-rich conditions were sintered to densities greater than 97% of theoretical. Appropriate doping with Sr or Ba

J. W. Stevenson; T. R. Armstrong; D. E. McCready; L. R. Pederson; W. J. Weber

1997-01-01

31

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

32

Laser induced breakdown spectroscopy diagnosis of rare earth doped optical glasses  

SciTech Connect

In the present work, rare earth (Nd, Eu, Er, Ho) doped oxyfluoroborate glasses were studied using laser induced breakdown spectroscopy (LIBS) technique. It has been observed that rare earth elements other than the doped one also reveal their presence in the spectrum. In addition the spectral lines of elements constituting the glass matrix have also been observed. Different plasma parameters such as plasma temperature and electron density have been estimated. It is concluded that the LIBS is a potential technique to identify simultaneously the light elements (B, O, F) as well as the heavy elements (Fe, Ba, Ca, Eu, Nd, Ho, Er) present in optical glasses.

Dwivedi, Y.; Thakur, S. N.; Rai, S. B.

2010-05-01

33

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

E-print Network

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

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

2013-01-01

34

Influence of rare earth doping on thermoelectric properties of SrTiO3 ceramics  

NASA Astrophysics Data System (ADS)

Thermoelectric properties of SrTiO3 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: SrTiO3 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 SrTiO3 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, Sr0.8La0.18Yb0.02TiO3 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 Sr0.8La0.2TiO3 (ZT = 0.26).

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

2013-12-01

35

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

36

Growth and stability of UV and VIS femtosecond written fiber Bragg gratings in different rare earth doped fibers  

NASA Astrophysics Data System (ADS)

Using femtosecond (fs) radiation and multi-photon absorption processes for fiber Bragg grating (FBG) inscription offers the advantage of writing FBGs independent of the chemical fiber composition. Especially for fiber laser applications the fabrication of FBGs integrated in rare earth doped fibers is a favorable option for monolithic fiber lasers. In this paper we report on the growth and stability of femtosecond generated fiber Bragg gratings in different rare earth doped fibers. For this purpose we use two different fs laser wavelengths at 266 nm and 400 nm and a modified Talbot- interferometer setup for the generation of first order Bragg gratings. We study the growth characteristics of FBGs in terms of reflectivity, Bragg wavelength and spectral grating width during the writing with UV and VIS fs radiation. For these experiments fibers drawn in-house at the IPHT are used, which possess varying contents of Ytterbium and/or Cerium with a comparable Phosphor and Aluminum co-doping and a standard geometry (125 ?m cladding, 8-10 ?m core diameter). We observe different kinds of grating growth processes depending on the inscription wavelength and the specific doping level of the fibers. It is possible to produce high reflective Type I gratings by UV fs exposure and high reflective Type II gratings with higher temperature stability by VIS fs exposure. The transformation from Type I to Type II gratings with a 400 nm inscription wavelength is studied in dependence on the exposure conditions. Our experimental results underline the role of doping for fs material photosensitivity and for FBG inscription process.

Fiebrandt, Julia; Lindner, Eric; Becker, Martin; Brückner, Sven; Rothhardt, Manfred; Bartelt, Hartmut

2011-08-01

37

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

38

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

Microsoft Academic Search

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

Nicklas Ohlsson; R Krishna Mohan; Stefan Kröll

2002-01-01

39

Ferrimagnetic Resonance in Rare-Earth Doped Yttrium Iron Garnet. I. Field for Resonance  

Microsoft Academic Search

Resonance experiments have been performed on YIG crystals doped with each of the rare earth ions except Lu, Gd, and Pm. Except for Ce these are thought to replace Y as trivalent ions. This paper presents measurements of the field for resonance in the (110) plane at 1.5°K for each of these samples. In several cases there are also data

J. F. Dillon; J. W. Nielsen

1960-01-01

40

Ferrimagnetic Resonance in Rare-Earth-Doped Yttrium Iron Garnet. III. Linewidth  

Microsoft Academic Search

Measurements of ferrimagnetic resonance linewidth have been made for single crystals of yttrium iron garnet (YIG) doped with each of the 4f rare earths (except Ce, Gd, Pm, and Lu). Starting from the lowest temperatures, the linewidth increases to a maximum in the range 30 to 150°K, and then decreases. Some structure is apparent in these curves; they are anisotropic;

J. F. Dillon

1962-01-01

41

The effects of rare earth doping on gallium nitride thin films  

NASA Astrophysics Data System (ADS)

The thermal neutron capture cross section of the rare earth (RE) metal isotope Gd-157 is the largest of all known natural elements, which distinguishes the material as a logical candidate for neutron detection. To address an incomplete understanding of rare earth doped Gallium Nitride (GaN) materials, investigations of the surface electronic structure and interface properties of GaN thin films doped with rare earths (Yb, Er, Gd) were undertaken. Lattice ion occupation, bonding, rare earth 4f occupation, and gold Schottky barrier formation were examined using synchrotron photoemission spectroscopy. Measured Debye temperatures indicate substitutional occupation of Ga sites by RE ions. The occupied RE 4f levels, deep within the valence band, suggest that intra-atomic f-f transitions may be more 'blue' than predicted by theoretical models. Thin layers of gold did not wet and uniformly cover the GaN surface, even with rare earth doping of the GaN. The resultant Schottky barrier heights for GaN:Yb, GaN:Er, and GaN:Gd, are 25--55% larger than those reported at the gold to undoped GaN interface. The utility of gadolinium as a neutron detection material was examined via fundamental nuclear and semiconductor physics. Low charge production and the large range of internal conversion electrons limits charge collection efficiency.

McHale, Stephen R.

42

Digital Earth system based river basin data integration  

NASA Astrophysics Data System (ADS)

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

Zhang, Xin; Li, Wanqing; Lin, Chao

2014-12-01

43

Integrating Customized Geographical Data Into Google Earth   

E-print Network

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

Hu, Chenwei

2011-11-24

44

Preparation and structural characterization of rare-earth doped lead lanthanum zirconate titanate ceramics  

NASA Astrophysics Data System (ADS)

A new preparation route towards rare-earth (RE) doped polycrystalline lead lanthanum zirconate titanate (PLZT) ceramics (RE = Y 3+, Nd 3+, Yb 3+), based on the use of doped lanthanum oxide or zirconia, is reported. Structural characterization by X-ray powder diffraction reveals that secondary phase formation can be substantially diminished in comparison to conventional preparation methods. The distribution of the rare-earth dopants was investigated as a function of concentration by static 207Pb spin echo NMR spectra, using Fourier Transformation of Carr-Purcell-Meiboom-Gill spin echo trains. For the Nd- and Yb-doped materials, the interaction of the 207Pb nuclei with the unpaired electron spin density results in significant broadening and shifting of the NMR signal, whereas these effects are absent in the diamagnetic Y 3+ doped materials. Based on different concentration dependences of the NMR lineshape parameters, we conclude that the structural role of the Nd 3+ dopants differs significantly from that of Yb 3+. While the Nd 3+ ions appear to be statistically distributed in the PLZT lattice, incorporation of Yb 3+ into PLZT appears to be limited by the appearance of doped cubic zirconia as a secondary phase.

de Queiroz, Thiago Branquinho; Mohr, Daniel; Eckert, Hellmut; de Camargo, Andrea S. S.

2009-08-01

45

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

SciTech Connect

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

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

2000-06-01

46

Doping alkaline-earth: a strategy of stabilizing hexagonal GdF3 at room temperature.  

PubMed

Hexagonal GdF3 is a more efficient phosphor host compared with the traditional orthorhombic form but the hexagonal phase is thermodynamically unstable at room temperature. Herein, we present a strategy to stabilize hexagonal GdF3 by doping with alkaline-earth ions in a mild hydrothermal reaction system. The selection of the dopant, effect of the dopant amount and the mechanism of the phase transition was discussed in detail. The luminescence variation of GdF3:Eu was demonstrated to verify the phase transformation. Furthermore, the upconversion luminescence of the Sr-doped and undoped GdF3:Yb/Er was investigated. PMID:24026018

Zhao, Qi; Shao, Baiqi; Lü, Wei; Jia, Yongchao; Lv, Wenzhen; Jiao, Mengmeng; You, Hongpeng

2013-11-21

47

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.

Ellen Mosley-Thompson

48

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

49

Structure and optical properties of rare earth-doped zinc oxyhalide tellurite glasses  

SciTech Connect

Zinc tellurite glasses appear to be excellent candidates for hosting rare earth ions since they provide a low phonon energy environment to minimize non-radiative losses as well as possess good chemical durability and optical properties. The optical behavior of the rare earth ion can be manipulated by modifying its local environment in the glass host. The authors report measurements of the emission lifetime, optical absorption, and vibrational density of states of the glass system (ZnO){sub x}(ZnF{sub 2}){sub y}(TeO{sub 2}){sub 1{minus}x{minus}y}doped (0.1 mol%) with a series of rare earths. Phonon sideband spectroscopy has been successfully employed to probe vibrational structure in the immediate vicinity of the rare earth ion. The authors observe a significant increase in the emission lifetime (from approximately 150 {mu}s to 250 {mu}s) of Nd{sup 3+} with increasing fluorine substitution.

Sidebottom, D.L.; Hruschka, M.A. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Chemical and Nuclear Engineering; Potter, B.G.; Brow, R.K. [Sandia National Labs., Albuquerque, NM (United States)

1997-10-01

50

Enhanced Thermopower in Nano-SrTiO3 Via Rare Earth Doping  

NASA Astrophysics Data System (ADS)

Doped perovskite titanates are known to exhibit non-linear electrical conductivity when they are in polycrystalline form. This non-linear behavior is attributed to the barrier potential at the grain boundary (GB). In this paper, we focus on the influence of the barrier potential on the thermopower (S) of rare earth (RE)-doped SrTiO3 with a grain size of 20 nm. |S| was found to increase linearly for smaller RE dopants despite the use of identical carrier concentrations. Capacitance-voltage measurements showed that the barrier potential increased linearly for the smaller RE dopants. Energy-selective scattering by the GB potential was evaluated theoretically, and allowed us to qualitatively explain the enhanced S in this system. The results indicate that the GB nature, which is a crucial factor for nanostructured thermoelectric materials, can be tuned by RE doping in this system.

Kinemuchi, Yoshiaki; Mimura, Ken-ichi; Kato, Kazumi

2014-12-01

51

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

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

52

Transport properties of rare earth doped La 2?x Sr x CuO 4  

Microsoft Academic Search

We present measurements of the resistivity, the thermopower, and the thermal conductivity of rare earth (RE) doped La2-xSrxCuO4. 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. Our results indicate that a suppressed phonon heat transport is a characteristic feature of La2CuO4

B. Büchner; A. Lang; O. Baberski; M. Hücker; A. Freimuth

1996-01-01

53

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

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

54

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

55

Google Maps and Google Earth Integration Using KML  

Microsoft Academic Search

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

D. Ricket

2006-01-01

56

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

NASA Astrophysics Data System (ADS)

Frequently observed deformation of P-E hysteresis loops of multiferroic BiFeO3 (BFO) and doped BFO by leakage currents hindered potential applications of BFO. Apart from the increased power consumption and heating due to leakage current, charge injection associated with the electrical transport properties (I-V) is also believed to be involved in accelerating fatigue as well as raising other reliability issues for real applications. Suitable thin film structure with selection of proper contacts as well as incorporating dopants in BFO, promising results were observed which significantly suppress the leakage current. However, bulk BFO specimen possesses appreciable difficulties for I-V measurements. In this paper, we have carried out electrical transport measurements on sub-millimeter thick bulk BFO and rare earth doped BFO applying different electrical contacts under high voltage biasing configuration. Gd and Ho doped BFO specimens were measured which were processed by slow step sintering schedule. Our experimental findings revealed that Gd & Ho doping in Fe deficient BFO promotes the suppression of oxygen vacancies and in turn reduce leakage current which support the P-E loop. Attempt has been made to explain above results by common transport models which includes Schottky, space charge limited conduction and Poole-Frenkel effect.

Pradhan, Sangram K.; Rout, Prajna P.; Das, Sangram K.; Roul, Binod K.

2011-11-01

57

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

58

Emission properties of heavy metal oxide glasses doped with rare-earths  

NASA Astrophysics Data System (ADS)

Emissions at 1.3?m and mid-infrared region from several rare-earths ions doped into PbO-Bi2O3-Ga2O3 glasses were investigated. Lifetime of the Pr3+:1G4 level was 53´s with a quantum efficiency of 9%. Emission at 2.73?m from Er3+, which is normally quenched in oxide glass, was evident and the lifetime of the upper emission level was approximately 900´s. Thermal stability of PbO-Bi2O3-Ga2O3 glass was considerably improved by adding 10 mole % of GeO2. Doping of Tm3+ and Ho3+ showed potentials for S-band fiber-optic amplification.

Heo, Jong

2003-07-01

59

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

60

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

NASA Astrophysics Data System (ADS)

Bulk crystals of the vanadates YVO 4 and GdVO 4 are well-known hosts for lanthanide ions and have been widely used in solid-state lasers as well as in phosphors. We report on the thin film growth of rare-earth-doped GdVO 4 by pulsed laser deposition. These films were grown either nearly homoepitaxially on YVO 4-substrates or heteroepitaxially on ?-Al 2O 3-substrates. The first spectroscopic results of an Eu-doped GdVO 4 film grown on YVO 4 with a film thickness of 100 nm clearly indicate crystalline growth as the resulting emission and excitation spectra correspond well with the spectra from the bulk system. To confirm in more detail the structure of the films, X-ray diffraction measurements have been performed.

Bär, S.; Scheife, H.; Huber, G.

2006-05-01

61

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

62

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

63

Study of Defects That Trap Excitons in Yttrium Aluminum Garnets Doped With Rare-Earth Elements  

NASA Astrophysics Data System (ADS)

Excitons play a fundamental role in transporting energy in photonic materials. Understanding and controlling excitons dynamics through their interactions with activating impurities and lattice defects is key to improving scintillation and optical properties. Singles crystals of yttrium aluminum garnet (YAG) crystals doped with rare-earths were studied by positron annihilation, thermolunuinescence and optical spectroscopy. Evidence of defect complexes was found in the YAG structure. Positron lifetime measurements were performed to characterize those defects. Effects of dopants on the optical properties and lattice defects were investigated.

Selim, Farida; Varnery, Chris; Collins, Gary; McKay, David; Reda, Sherif

2011-03-01

64

Luminescence and structural properties of RbGdS2 compounds doped by rare earth elements  

NASA Astrophysics Data System (ADS)

Rare earth elements (Pr, Ce) doped ternary sulfides of formula RbGd1-xRExS2 were synthesized in the form of crystalline hexagonal platelets by chemical reaction under the flow of hydrogen sulfide. The X-ray powder diffraction detected only a single crystalline phase of rhombohedral lattice system. Optical properties of studied systems are investigated by methods of time-resolved luminescence spectroscopy. Thermal stability of the Pr3+ emission is demonstrated. Application potential in the white light-emitting diode solid state lighting or X-ray phosphors is discussed.

Jarý, V.; Havlák, L.; Bárta, J.; Mihóková, E.; Nikl, M.

2013-04-01

65

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

PubMed Central

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

66

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

67

Properties and Applications of Laser-Induced Gratings in Rare Earth Doped Glasses.  

NASA Astrophysics Data System (ADS)

Scope and method of study. Four-wave-mixing techniques were used in an attempt to create permanent laser-induced grating in Pr^{3+}-, Nd ^{3+}-, Eu^ {3+}-, and Er^{3+ }-doped glasses. The permanent laser-induced grating signal intensity and build-up and erase times were investigated as function of the write beam crossing angle, write beam power, and temperature. Thermal lensing measurements were conducted on Eu^{3+} - and Nd^{3+}-doped glasses and room temperature Raman and resonant Raman spectra were obtained for Eu^{3+}-doped glasses. The permanent laser-induced grating signal intensity was studied in Eu^{3+} -doped alkali-metal glasses as a function of the alkali -metal network modifier ion and a model was developed by treating the sample as a two-level system. Optical device applications of the permanent laser-induced gratings were studied by creating some simple devices. Findings and conclusions. Permanent laser-induced gratings were created in the Pr^{3+ }- and Eu^{3+} -doped glasses. The permanent laser-induced grating is associated with a structural phase change of the glass host. The structural change is produced by high energy phonons which are emitted by radiationless relaxation processes of the rare earth ion. Nd^{3+} and Er^{3+} relax nonradiatively by the emission of phonons of much lower energy which are unable to produce the structural phase change needed to form a permanent laser-induced grating. The difference in energy of the emitted phonons is responsible for the differing characteristics of the thermal lensing experiments. The model does a good job of predicting the experimental results for the asymmetry and other parameters of the two-level system. The application of these laser -induced gratings for optical devices demonstrates their importance to optical technology.

Behrens, Edward Grady

68

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

NASA Astrophysics Data System (ADS)

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

McDonald, K. R.

2007-12-01

69

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

70

Up-conversion visible emission in rare-earth doped fluoride glass waveguides  

NASA Astrophysics Data System (ADS)

The paper presents the visible emissions through frequency up-conversion and energy transfer process in the waveguide rare-earth (RE) codoped with RE/Yb (RE=Er, Pr, Tm), as well as physical properties of fluoride glasses and their fabrication par physical vapor deposition. The RE doping is made by substituting LaF in the base ZLAG glass composition (70%ZrF4-23.5%LaF3-0.5%AlF3-6%GaF3). Under 980-nm excitation, the emissions in planar waveguides of 2 to 3 thickness are found similar to the ones observed in bulk; blue and red emissions for 0.5Pr/xYb codoping and blue emission for 0.75Tm/xYb codoping with x ranging from 1 to 5 mol%. The bulk glass doped with Er/Tm/Yb can generate simultaneously and with high efficiency red-green-blue emissions from single-wave pumping at 980 nm. These preliminary results show that Er/Tm/Yb triply doped ZLA waveguide is a potential material for compact white light sources.

Boulard, Brigitte; Dieudonné, Belto; Gao, Youping; Chiasera, Alessandro; Ferrari, Maurizio

2014-07-01

71

Synthesis and photoluminescent behavior of Eu3+-doped alkaline-earth tungstates  

NASA Astrophysics Data System (ADS)

Eu3+-doped alkaline-earth tungstates MWO4 (M=Ca2+, Sr2+, Ba2+) were prepared by a polymeric precursor method based on the Pechini process. The polymeric precursors were calcined at 700 °C for 2 h in order to obtain well-crystallized powders and then characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and photoluminescence spectroscopy (PL). All prepared samples showed a pure crystalline phase with scheelite-type structure confirmed by XRD. It was noted that the charge-transfer band shifted from 260 to 283 nm when calcium is replaced by strontium. However, this band was not observed for Eu3+-doped barium tungstate. Upon excitation at 260 nm, the emission spectra are dominated by the red 5D0?7F2 transition at 618 nm. By analyzing of the emission lines, it was inferred that Eu3+ ions occupy low symmetry sites in the host lattice. It was also found that Eu3+-doped SrWO4 displays better chromaticity coordinates and greater luminescence intensity than the other samples.

Barros, B. S.; de Lima, A. C.; da Silva, Z. R.; Melo, D. M. A.; Alves-Jr, S.

2012-05-01

72

Excess modes and enhanced scattering in rare-earth-doped amorphous silicon thin films  

NASA Astrophysics Data System (ADS)

We report specific heat and thermal conductivity of gadolinium- and yttrium-doped amorphous silicon thin films measured using silicon-nitride membrane-based microcalorimeters. Addition of gadolinium or yttrium to the amorphous silicon network reduces the thermal conductivity over a wide temperature range while significantly increasing the specific heat. This result indicates that a large number of nonpropagating states are added to the vibrational spectrum that are most likely caused either by localized vibration of the dopant atom in a Si cage or softening of the material forming the cage structures. High-resolution cross-sectional electron micrographs reveal columnar features in Gd-doped material which do not appear in pure amorphous silicon. Scattering from both the nanoscaled columns and the filled-cage structures play a role in the reduced thermal conductivity in the rare-earth-doped amorphous semiconductor. The overall result is an amorphous solid with a large bump in C/T3 and no plateau in thermal conductivity.

Zink, B. L.; Islam, R.; Smith, David J.; Hellman, F.

2006-11-01

73

Comparative study of magnetic properties of dilute Fe doped with transition magnetic ions and GaN, InN doped with rare-earth magnetic ions  

NASA Astrophysics Data System (ADS)

We report on ab initio computational results for the density of state (DOS) and local magnetic moment of Fe alloys lightly doped with 3d Cr and Mn transition metals impurities. The DOS and local magnetic moment of both doped systems were calculated using spin local-density approximation within the framework of density functional theory by employing the Korringa-Kohn-Rostoker Green's-function and LIyod's methods. Our results show drastic variations of DOS and local magnetic moments of both doped systems as compared to that of pure Fe. Our results agree fairly well with the available experimental results on Fe doped with 3d and 4d transition impurities. In addition, the effective magnetic moments of GaN and InN doped with rare-earth magnetic ions have been calculated using Vienna ab initio simulation package (VASP) and Cowan's atomic Hartree-Fock (HF) code with relativistic correction. Our results indicate that doping a non-magnetic compounds with a magnetic impurity leads to an effective magnetic dipole moment that are quite larger than the magnetic moment obtained by doping a magnetic material with a magnetic impurity.

Alsaad, A.; Qattan, I. A.

2014-01-01

74

Composition-driven structural phase transitions in rare-earth-doped bifeo3 ceramics: a review.  

PubMed

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

Arnold, Donna

2015-01-01

75

Sol-gel synthesis of rare-earth-doped halide optical materials for photonic applications  

NASA Astrophysics Data System (ADS)

Halides have received global attention as potential ultra-low loss optical fiber materials and luminescent sources for all-optical amplification in modern telecommunication systems operating at 1.3 and 1.55 ?m. Unfortunately, conventional processing methods currently have failed in their efforts to produce even near-intrinsic material properties. Based on the well- established notion that sol-gel techniques offer high purity, low processing temperature, and compositionally flexible routes to high quality optics, we examined solution-based approaches to the synthesis of rare-earth- doped halides that provide luminescence in the 1.3 ?m and 1.55 ?m telecommunication windows. Initial studies into metal-organic-derived, ZBLA fluoride glass thin-films proved the spectroscopic performance of dopants was dominated by nonradiative relaxations caused by the presence of remnant carbonaceous species from the precursors. Heat treatments to above the point of glass devitrification did not resolve this problem and dopant emission remained modified by these extrinsic sources of high energy phonons. Inorganic precursors then were studied to circumvent the issues associated with the residual organics. Amorphous and crystalline single-component halide systems were prepared from aqueous solutions of inorganic chloride salts and their luminescence properties at 1.3 and 1.55 ?m studied. Pr3+- and Dy3+- doped LaF3 and LaCl3 powders were prepared that exhibited 1.3 ?m radiative quantum efficiencies of 72 and 78%, respectively, despite chemical analyses that indicated greater than 2% oxide concentrations. The efficiency values represented the highest measured from any halide to-date. Superiority in spectroscopic performance with respect to melt-grown, single-crystal analogs clearly opposed the widely accepted belief that quantum efficiencies are seriously degraded by precursor purity or the presence of oxygen. The results validated our hypothesis that inexpensive, low temperature, aqueous solution-derived materials can possess low-phonon energies. Luminescence was observed at 1.55 ?m from Er3+-doped LaF3 prepared by a single-step, solution-fluorination method. Available emission bandwidths 360% larger than current optical amplifier materials were realized from highly rare-earth-doped LaF3 transparent gels. The aqueous solution synthesis was found to permit rare-earth solid solubility ranges nearly 50 mole % greater than melt-grown equivalents. This compositional metastability was shown to be process-induced and verified our hypothesis that novel compositional flexibility is enabled by solution- based approaches.

Ballato, John Michael

76

The EPOS Architecture: Integrated Services for solid Earth Science  

NASA Astrophysics Data System (ADS)

The European Plate Observing System (EPOS) represents a scientific vision and an IT approach in which innovative multidisciplinary research is made possible for a better understanding of the physical processes controlling earthquakes, volcanic eruptions, unrest episodes and tsunamis as well as those driving tectonics and Earth surface dynamics. EPOS has a long-term plan to facilitate integrated use of data, models and facilities from existing (but also new) distributed research infrastructures, for solid Earth science. One primary purpose of EPOS is to take full advantage of the new e-science opportunities coming available. The aim is to obtain an efficient and comprehensive multidisciplinary research platform for the Earth sciences in Europe. The EPOS preparatory phase (EPOS PP), funded by the European Commission within the Capacities program, started on November 1st 2010 and it has completed its first two years of activity. EPOS is presently mid-way through its preparatory phase and to date it has achieved all the objectives, milestones and deliverables planned in its roadmap towards construction. The EPOS mission is to integrate the existing research infrastructures (RIs) in solid Earth science warranting increased accessibility and usability of multidisciplinary data from monitoring networks, laboratory experiments and computational simulations. This is expected to enhance worldwide interoperability in the Earth Sciences and establish a leading, integrated European infrastructure offering services to researchers and other stakeholders. The Preparatory Phase aims at leveraging the project to the level of maturity required to implement the EPOS construction phase, with a defined legal structure, detailed technical planning and financial plan. We will present the EPOS architecture, which relies on the integration of the main outcomes from legal, governance and financial work following the strategic EPOS roadmap and according to the technical work done during the first two years in order to establish an effective implementation plan guaranteeing long term sustainability for the infrastructure and the associated services. We plan to describe the RIs to be integrated in EPOS and to illustrate the initial suite of integrated and thematic core services to be offered to the users. We will present examples of combined data analyses and we will address the importance of opening our research infrastructures to users from different communities. We will describe the use-cases identified so far in order to allow stakeholders and potential future users to understand and interact with the EPOS infrastructure. In this framework, we also discuss the global perspectives for data infrastructures in order to verify the coherency of the EPOS plans and present the EPOS contributions. We also discuss the international cooperation initiatives in which EPOS is involved emphasizing the implications for solid Earth data infrastructures. In particular, EPOS and the satellite Earth Observation communities are collaborating in order to promote the integration of data from in-situ monitoring networks and satellite observing systems. Finally, we will also discuss the priorities for the third year of activity and the key actions planned to better involve users in EPOS. In particular, we will discuss the work done to finalize the design phase as well as the activities to start the validation and testing phase of the EPOS infrastructure.

Cocco, Massimo; Consortium, Epos

2013-04-01

77

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

E-print Network

28th European Photovoltaic Solar Energy Conference and Exhibition 1.BO11.2 DOWN CONVERTER DEVICE COMBINING RARE-EARTH DOPED THIN LAYER AND PHOTONIC CRYSTAL FOR C-SI BASED SOLAR CELL Thierry Deschamps1 structure combines rare-earths doped thin layer allowing the down-conversion process with a photonic crystal

Paris-Sud XI, Université de

78

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

NASA Astrophysics Data System (ADS)

The integration of data is essential to make transformative progress in understanding the complex processes operating at the Earth’s surface and within its interior. While our current ability to collect massive amounts of data, develop structural models, and generate high-resolution dynamics models is well developed, our ability to quantitatively integrate these data and models into holistic interpretations of Earth systems is poorly developed. We lack the basic tools to realize a first-order goal in Earth science of developing integrated 4D models of Earth structure and processes using a complete range of available constraints, at a time when the research agenda of major efforts such as EarthScope demand such a capability. Among the challenges to 3D data integration are data that may be in different coordinate spaces, units, value ranges, file formats, and data structures. While several file format standards exist, they are infrequently or incorrectly used. Metadata is often missing, misleading, or relegated to README text files along side the data. This leaves much of the work to integrate data bogged down by simple data management tasks. The OpenEarth Framework (OEF) being developed by GEON addresses these data management difficulties. The software incorporates file format parsers, data interpretation heuristics, user interfaces to prompt for missing information, and visualization techniques to merge data into a common visual model. The OEF’s data access libraries parse formal and de facto standard file formats and map their data into a common data model. The software handles file format quirks, storage details, caching, local and remote file access, and web service protocol handling. Heuristics are used to determine coordinate spaces, units, and other key data features. Where multiple data structure, naming, and file organization conventions exist, those heuristics check for each convention’s use to find a high confidence interpretation of the data. When no convention or embedded data yields a suitable answer, the user is prompted to fill in the blanks. The OEF’s interaction libraries assist in the construction of user interfaces for data management. These libraries support data import, data prompting, data introspection, the management of the contents of a common data model, and the creation of derived data to support visualization. Finally, visualization libraries provide interactive visualization using an extended version of NASA WorldWind. The OEF viewer supports visualization of terrains, point clouds, 3D volumes, imagery, cutting planes, isosurfaces, and more. Data may be color coded, shaded, and displayed above, or below the terrain, and always registered into a common coordinate space. The OEF architecture is open and cross-platform software libraries are available separately for use with other software projects, while modules from other projects may be integrated into the OEF to extend its features. The OEF is currently being used to visualize data from EarthScope-related research in the Western US.

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

2009-12-01

79

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

SciTech Connect

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

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

2001-05-01

80

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

81

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

82

New Characteristic in the Temperature Dependence of Ferrimagnetic Resonance Linewidth in Some Rare-Earth Doped Yttrium Iron Garnets  

Microsoft Academic Search

Measurements have been made of the ferrimagnetic resonance linewidth of YIG doped with each of the rare earths. These results will be presented in full elsewhere. For the most part there is a peak in the ?H(T) curve at some temperature between 20° and 150°K. The position of this peak varies with the impurity, the frequency, and the crystal direction

J. F. Dillon

1961-01-01

83

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

84

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

85

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

SciTech Connect

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

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

2011-06-15

86

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

87

On the optical properties of undoped and rare-earth-doped yttrium aluminium garnet single crystals  

NASA Astrophysics Data System (ADS)

Optical absorption and photoluminescence (PL) measurements were performed on single crystals of undoped Y3Al5O12 (YAG) and a number of rare-earth-doped YAG to study the effect of dopant type and concentration, growth atmosphere, post-growth annealing and UV irradiation on the optical properties of YAG crystals. The presence of hydrogen in the growth atmosphere was found to be essential for enhancing the incorporation of Ce ions in the Ce3+ state in Ce-doped YAG (Ce?:?YAG). Annealing in air was shown to have no effect on the PL emission of Ce?:?YAG crystals. An absorption peak around 256 nm was observed in the undoped YAG and Ce?:?YAG crystals after air anneal at 1200 °C. Optical absorption and annealing experiments support the association of the 256 nm peak with Fe impurities and oxygen ions. UV irradiation modifies the valency of impurities and generates electronic defects leading to an increase in the optical density of YAG crystals. Optimizing the growth and annealing conditions is critical in order to develop Ce?:?YAG single crystals as efficient scintillators.

Varney, C. R.; Mackay, D. T.; Reda, S. M.; Selim, F. A.

2012-01-01

88

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

89

Monte Carlo simulation of radiation pattern for rare earth ions doped luminescent glasses under violet LED excitation  

NASA Astrophysics Data System (ADS)

Rare earth ions doped luminescence glasses are promising phosphor candidates in the fabrication of LEDs in the future due to their specific advantages such as higher thermal stability, higher transparency, compared to current commercial LEDs. While radiation patterns of luminescent glasses are different from current commercial LEDs fabricated by phosphors, luminescent glasses play roles both in emitting light and adjusting light distribution. In order to investigate radiation pattern of luminescent glasses, luminescence physical model of flat glasses doped with single rare earth ion was presented. Process of photons acting on rare earth ions and transporting in the luminescent glasses, and output light distribution from luminescent glasses were analyzed based on violet LED. At last, the simulating of radiation pattern for luminescent glasses based on Monte Carlo ray-tracing method was proved by experiment.

Lei, Xiaohua; Feng, Yong'an; Chen, Weimin; Zhang, Peng; Ren, Linjiao; Du, Xiaoqing

2013-09-01

90

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

91

Postgraduate Education in Earth and Environmental Sciences: an Integrated Concept  

NASA Astrophysics Data System (ADS)

Today's graduate and postgraduate education in the field of Earth System and Environmental Science is a highly interdisciplinary and inter-institutional challenge. The integration of observations, palaeoclimate data, and climate modelling requires networks and collaborations of experts and specialists in order to better understand natural climate variations over a broad range of timescales and disciplines, and to cope with the challenges of recent climate change. The existing research infrastructure at the Alfred-Wegener-Institut Bremerhaven (AWI), University of Bremen (Uni-HB), and Jacobs University Bremen offers a unique research environment in north-western Germany to study past, present and future changes of the climate system, with special focus on high latitudinal processes. It covers all kind of disciplines, climate science, geosciences and biosciences, and provides a consistent framework for education and qualification of a new generation of expertly trained, internationally competitive master and PhD students. On postgraduate level, the Postgraduate Programme Environmental Physics (PEP) at University of Bremen (www.pep.uni-bremen.de) educates the participants on the complex relationship between atmosphere, hydrosphere (ocean), cryosphere (ice region) and solid earth (land). Here, the learning of experimental methods in environmental physics at the most advanced level, numerical data analysis using supercomputers, and data interpretation via sophisticated methods prepare students for a scientific career. The foundation of an Earth System Research School (ESSReS) (www.earth-system-science.org) at the AWI enables PhD students from a variety of disciplines to cooperate and exchange views on the common theme of ‘linking data and modelling', leading to a better understanding of local processes within a global context. Computational and conceptual models of the Earth system provide the ability to investigate different scenarios in biogeochemistry, such as the carbon cycle, the structure of marine sediments, and isotope distribution in climate components. Training and education, especially in time-series and data analysis, is a common key component for all participants. The Helmholtz graduate school for Polar and Marine Research (POLMAR) (polmar.awi.de), beyond the aforementioned programmes in further cooperation with the Max Planck Institute for Microbiology, Bremen, the University Potsdam, Bremerhaven University of Applied Science and the Institute for Marine Resources (IMARE), provides a consistent framework for education and qualification for PhD students in general. Developing all categories of skills needed for analysing complex climate and environmental systems and the development of integrated solutions in a supportive network of collaborating research institutions fosters outstanding career options. Structured training and supervision supported by a broad range of transferrable skill development courses is indicative for the entire concept. This structured and integrated educational concept provides a strong basis for qualifying the next generation of excellent scientists for the challenging questions in Earth System Science and Polar and Marine Research.

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

2009-04-01

92

An Integrated Concept on Earth and Environmental Sciences Postgraduate Education  

NASA Astrophysics Data System (ADS)

Today's graduate and postgraduate education in the field of Earth System and Environmental Science is a highly interdisciplinary and inter-institutional challenge. The integration of observations, palaeoclimate data, and climate modelling requires networks and collaborations of experts and specialists in order to better understand natural climate variations over a broad range of timescales and disciplines, and to cope with the challenges of recent climate change. The existing research infrastructure at the Alfred-Wegener-Institut Bremerhaven (AWI), University of Bremen, and Jacobs University Bremen offers a unique research environment in north-western Germany to study past, present and future changes of the climate system, with special focus on high latitudinal processes. It covers all kind of disciplines, climate science, geosciences and biosciences, and provides a consistent framework for education and qualification of a new generation of expertly trained, internationally competitive master and PhD students. On postgraduate level, the Postgraduate Programme Environmental Physics (PEP) at the University of Bremen (www.pep.uni-bremen.de) educates the participants on the complex relationship between atmosphere, hydrosphere (ocean), cryosphere (ice region) and solid earth (land). Here, the learning of experimental methods in environmental physics at the most advanced level, numerical data analysis using supercomputers, and data interpretation via sophisticated methods prepare students for a scientific career. Within cooperation with the Ocean University of China (OUC) students are participating one year in the PEP programme during their master studies since 2006, to get finally a double degree of both universities. Based on this successful cooperation a similar programme is in preparation with the Lulea University of Technology, Sweden. The Earth System Science Research School (ESSReS) (www.earth-system-science.org) at the AWI enables PhD students from a variety of disciplines to cooperate and exchange views on the common theme of ‘linking data and modelling', leading to a better understanding of local processes within a global context. Computational and conceptual models of the Earth system provide the ability to investigate different scenarios in biogeochemistry, such as the carbon cycle, the structure of marine sediments, and isotope distribution in climate components. Training and education, especially in time-series and data analysis, is a common key component for all participants. The Helmholtz Graduate School for Polar and Marine Research (POLMAR) (polmar.awi.de), beyond the aforementioned programmes in further cooperation with the Max Planck Institute for Marine Microbiology, Bremen, the University of Potsdam, Bremerhaven University of Applied Science and the Institute for Marine Resources (IMARE), provides a consistent framework for education and qualification for PhD students in general. Developing all categories of skills needed for analysing complex climate and environmental systems and the development of integrated solutions in a supportive network of collaborating research institutions fosters outstanding career options. Structured scientific training and supervision supported by a broad range of transferable skills development courses is indicative for the entire concept. This structured and integrated educational concept provides a strong basis for qualifying the next generation of excellent scientists for the challenging questions in Earth System Science and Polar and Marine Research.

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

2010-05-01

93

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

94

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

NASA Astrophysics Data System (ADS)

Applications for infrared-transmitting non-oxide glass fibers span a broad range of topics. They can be used in the military, the medical field, telecommunications, and even in agriculture. Rare earth ions are used as dopants in these glasses in order to stimulate emissions in the infrared spectral region. In order to extend the host glass transmission further into the infrared, selenium atoms were substituted for sulfur in the established Ge-S-I chalcohalide glass system and the fundamental properties of these latter glasses were explored. Over 30 different compositions in the Ge-Se-I glass system were investigated as to their thermal and optical properties. The resulting optimum host with a composition of Ge15Se80I5 has a broad transmission range from 0.7 mum to 17.0 mum and a high working range over 145°C. The host glass also exhibited a Tg of 125°C, making rotational casting of a cladding tube for rod-and-tube fiberization a possibility. The base glass was doped with 1000 to 4000 ppm/wt of erbium, dysprosium, or neodymium. When doped with Er3+-ions, absorptions at 1.54 mum and 3.42 mum were observed. Nd3+-doping resulted in an absorption peak near 4.24 mum and Dy3+ ions caused absorption at 1.30 mum. Fluorescence emissions were found for neodymium at 1.396 mum with a FWHM of 74 nm, and for dysprosium at 1.145 mum with a FWHM of 75 nm, at 1.360 mum with a FWHM of 98 rim and at 1.674 mum with a FWHM of 60 nm. High optical quality tubes of the host glass could be formed using rotational casting in silica ampoules. Glass tubes, 4 to 6 cm long with a 1 cm outer diameter and a tailored inner-hole diameter ranging from 0.4 to 0.6 cm could be synthesized by this process with excellent dimensional tolerances around the circumference as well as along the length. A preform of this size provided 25 continuous meters of unclad fiber with diameters ranging from 140 to 200 mum. A UV-curable acrylate cladding was applied via an external coating cup. An x-ray analysis of the resulting fiber verified the constituents of the fiber. Due to tradeoffs between thermal properties, optical properties and rare earth solubility, the Ge-Se-I glass system must still be optimized prior to use as an active fiber device. Nevertheless, the viability of this host system has been demonstrated in this investigation. Some very promising advantages to adding halides to chalcogenide glass systems have been confirmed, including the tailoring of glass transition temperatures, enhancement of rare earth solubility, expanded fluorescence emissions in the IR, and suppression of some impurity absorption bands. Also, the potential for rod-and-tube fiberization utilizing the rotational casting method for tube synthesis has been established along with its resulting pristine core-clad interface. This research provides a foundation for active fiber device applications in the 2 to 10 mum spectral region.

Debari, Roberto Mauro

95

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.; Masó, J.; Cornford, D.; Díaz, P.; Lumsden, J.

2013-01-01

96

An integrated view of data quality in Earth observation.  

PubMed

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; Masó, J; Cornford, D; Díaz, P; Lumsden, J

2013-01-28

97

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

98

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

99

Computer modelling of intrinsic defects and rare earth doping in KYF4, K2YF5 and KY3F10  

NASA Astrophysics Data System (ADS)

A computational study of KYF4, KY3F10 and K2YF5 is presented. Energy minimisation techniques have been used to obtain structural models of the materials and intrinsic defect calculations have been performed. Rare earth doping has been considered at all cation sites and solution energies are presented which show the preference of isovalent doping at the Y3+ site.

Maddock, E. M.; Jackson, R. A.; Valerio, M. E. G.

2010-11-01

100

Preparation and Photocatalysis Properties of Bacterial Cellulose\\/TiO2 Composite Membrane Doped with Rare Earth Elements  

Microsoft Academic Search

Bacterial cellulose (BC) was chosen as a support for nanometer titanium dioxide (TiO2) particles due to its superfine network structure. The composite membrane of TiO2\\/BC doped with rare earth elements was prepared by a sol-gel method using tetraisopropyl titanate as starting material. Photocatalysis properties of this composite membrane were estimated by using methyl orange as a degradation agent. X-ray fluorescence

Xiuju Zhang; Wenbin Chen; Zhidan Lin; Jia Yao; Shaozao Tan

2011-01-01

101

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

Microsoft Academic Search

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

Tadatsugu Minami; Takashi Yamamoto; Toshihiro Miyata

2000-01-01

102

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

103

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

104

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

PubMed

In this paper, we demonstrate the use of continuous hydrothermal flow synthesis (CHFS) technology to rapidly produce a library of 56 crystalline (doped) zinc oxide nanopowders and two undoped samples, each with different particle properties. Each sample was produced in series from the mixing of an aqueous stream of basic zinc nitrate (and dopant ion or modifier) solution with a flow of superheated water (at 450 °C and 24.1 MPa), whereupon a crystalline nanoparticle slurry was rapidly formed. Each composition was collected in series, cleaned, freeze-dried, and then characterized using analytical methods, including powder X-ray diffraction, transmission electron microscopy, Brunauer-Emmett-Teller surface area measurement, X-ray photoelectron spectroscopy, and UV-vis spectrophotometry. Photocatalytic activity of the samples toward the decolorization of methylene blue dye was assessed, and the results revealed that transition metal dopants tended to reduce the photoactivity while rare earth ions, in general, increased the photocatalytic activity. In general, low dopant concentrations were more beneficial to having greater photodecolorization in all cases. PMID:25602735

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

2015-02-01

105

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

SciTech Connect

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

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

2011-01-01

106

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

107

First-principles calculation on oxygen ion migration in alkaline-earth doped La2GeO5.  

PubMed

By using first-principles calculations based on the density functional theory, we investigated the doping effects of alkaline-earth metals (Ba, Sr and Ca) in monoclinic lanthanum germanate La2GeO5 on its oxygen ion conduction. Although the lattice parameters of the doped systems changed due to the ionic radii mismatch, the crystal structures remained monoclinic. The contribution of each atomic orbital to electronic densities of states was evaluated from the partial densities of states and partial charge densities. It was confirmed that the materials behaved as ionic crystals comprising of cations of La and dopants and anions of oxygen and covalently formed GeO4. The doping effect on the activation barrier for oxygen hopping to the most stable oxygen vacancy site was investigated by the climbing-image nudged elastic band method. By tracing the charge density change during the hopping, it was confirmed that the oxygen motion is governed by covalent interactions. The obtained activation barriers showed excellent quantitative agreements with an experiment for the Ca- and Sr-doped systems in low temperatures as well as the qualitative trend, including the Ba-doped system. PMID:24888249

Linh, Tran Phan Thuy; Sakaue, Mamoru; Meñez Aspera, Susan; Alaydrus, Musa; Wungu, Triati Dewi Kencana; Linh, Nguyen Hoang; Kasai, Hideaki; Mohri, Takahiro; Ishihara, Tatsumi

2014-06-25

108

First-principles study on defect chemistry and migration of oxide ions in ceria doped with rare-earth cations.  

PubMed

Oxygen transport in rare-earth oxide (RE(2)O(3)) doped CeO(2) with fluorite structure has attracted considerable attention owing to both the range of practical usage (e.g., fuel cells, sensors, etc.) and the fundamental fascination of fast oxide ion transport in crystalline solids. Using density-functional theory, we have calculated the formation energies of point defects and their migration properties in RE(2)O(3) doped CeO(2)(RE = Sc, Y, La, Nd, Sm, Gd, Dy, and Lu). The calculated results show that oxygen vacancies are the dominant defect species obtained by RE(3+) doping. They form associates with the RE(3+) ions, and the corresponding defect association energy is a strong function of the ionic radii of the RE(3+) dopants. The migration of an oxygen vacancy was investigated using the nudged elastic band method. The lowest activation energy for oxygen vacancy hopping is obtained for a straightforward migration path between two adjacent oxygen sites. The migration energy of an oxygen vacancy also strongly depends on the ionic radii of the neighbouring dopant cations. Accordingly, we have identified two factors that affect the oxygen vacancy migration; (1) trapping (or repelling) of an oxygen vacancy at the NN site of the RE(3+) dopant, and (2) reduction (or enlargement) of the migration barrier by RE(3+) doping. These findings provide insight for atomistic level understanding of ionic conductivity in doped ceria and would be beneficial for optimizing ionic conductivity. PMID:19370220

Nakayama, Masanobu; Martin, Manfred

2009-05-01

109

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

110

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

NASA Astrophysics Data System (ADS)

Thermal barrier coatings with lower thermal conductivity improve the efficiency of gas turbine engines by allowing higher operating temperatures. Recent studies were shown that coatings containing a pair of rare-earth oxides with equal molar ratio have lower thermal conductivity and improved sintering resistance compared to the undoped 4-4.5 mol.% yttria-stabilized zirconia (YSZ). In the present work, rare-earth doped coatings were fabricated via suspension plasma spray by spraying YSZ powder-ethanol suspensions that contained dissolved rare-earth nitrates. The compositions of the coatings determined by inductively coupled plasma mass spectroscopy verified that 68 +/- 8% of the rare-earth nitrates added into the suspension was incorporated into the coatings. Two coatings containing different concentrations of the same dopant pair (Nd2O3/Yb2O3), and three coatings having similar concentrations of different dopant pairs (Nd 2O3/Yb2O3, Nd2O3/Gd 2O3, and Gd2O3/Yb2O 3) were produced and compared. The effect of dopant concentration and dopant pair type on the microstructure and properties of the coatings in the as-sprayed and heat treated conditions were investigated using XRD, SEM, TEM, STEM-EDX, and the laser flash method. The cross-sectional morphology of all coatings displayed columnar structure. The porosity content of the coating was found to increase with increasing dopant concentration, but did not significantly change with dopant pairs. Similarly, increasing the Nd2O3/Yb2O 3 concentration lowered the thermal conductivity of the as-sprayed coatings. Although the effect of changing dopant pair type is not as significant as increasing the dopant concentration, the coating that contained Gd2O 3/Yb2O3 exhibited the lowest conductivity compared to coatings that had other dopant pairs. Thermal conductivity measurement performed on the heat treated coatings indicated a larger conductivity increase for the rare-earth doped coatings. A detailed study on the microstructural change of the coatings after various heat treatments at 1200°C and 1300°C showed evidence of crack healing and grain growth. Comparison between the rare-earth dopant distribution of a selected coating before and after a 1300°C/50 hr heat treatment suggests the possibility of dopant rearrangement, which can further increase the thermal conductivity. An explanation on the difference in the properties of the rare-earth doped coatings produced by SPS and conventional processes was discussed.

Gong, Stephanie

111

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

112

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

SciTech Connect

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

Le Nguyen, An-Dien

1996-05-01

113

Rare-Earth Ion Relaxation Time and G Tensor in Rare-Earth-Doped Yttrium Iron Garnet. I. Ytterbium  

Microsoft Academic Search

Microwave-resonance measurements at 9.3 and 16.8 Gc\\/sec between 1.5 and 300°K in the principal crystallographic directions of a single-crystal of yttrium iron garnet (YIG) doped with 5.1% Yb are compared with the predictions of the longitudinal (so-called \\

Barry H. Clarke; K. Tweedale; R. W. Teale

1965-01-01

114

Rare-Earth Ion Relaxation Time and G Tensor in Rare-Earth-Doped Yttrium Iron Garnet. II. Neodymium  

Microsoft Academic Search

We present ferrimagnetic-resonance linewidth measurements at 9.3 Gc\\/sec and 16.9 Gc\\/sec between 1.5 and 250°K in the principal crystallographic directions for a single crystal of yttrium iron garnet (YIG) doped with 0.82% Nd. These results are compared with the linewidth predicted by the longitudinal (so-called \\

Barry H. Clarke

1965-01-01

115

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...

116

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

117

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

118

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

119

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

SciTech Connect

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

Yan, Zhi-Yuan; Yan, Bing, E-mail: byan@tongji.edu.cn; Jia, Li-Ping

2013-10-15

120

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

121

Frequency upconversion and imaging using rare-earth doped colloidal nanoprobes  

E-print Network

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

Polman, Albert

122

Dosimetric studies of YAlO3: Mn co-doped with transition (Co, Cu, Fe) and rare earth (Yb, Ce) metal ions  

NASA Astrophysics Data System (ADS)

Dosimetric studies on single crystals of YAlO3:Mn co-doped with transition (Co, Cu, Fe) and rare earth (Yb, Ce) metal ions using UV radiation exposure for the duration 5-30 min have been studied. A single well resolved thermoluminescence glow peak was observed at 183 °C in Co and Cu co-doped single crystals. In Fe co-doped single crystals, two well resolved glow peaks at 196 °C and 238 °C were observed. A well resolved glow peak at 215 °C in Yb and 176 °C in Ce co-doped single crystals was observed. Variations of thermoluminescent (TL) glow peaks intensity in all the co-doped crystals with different UV-exposures were studied. TL glow peak intensity increases sublinearly in Co, Cu co-doped crystals, whereas in Fe co-doped crystals glow peaks at 196 °C and 238 °C increase linearly. Fading effect was studied at different intervals up to 30 d for all co-doped crystals exposed to UV source for 10 min. Strong fading was observed initially and stabilized after 15 d. Fe co-doped YAlO3:Mn2+ records 40% fading, whereas other samples of YAlO3:Mn2+ co-doped with Cu, Co, Yb and Ce show 60% fading. The kinetic parameters (E, b, s) were estimated using glow peak shape method for UV irradiated samples and results are discussed in detail.

Premkumar, H. B.; Nagabhushana, H.; Sharma, S. C.; Prashantha, S. C.; Nagabhushana, B. M.; Nagaswarupa, H. P.; Zhao, Guangjun; Chen, Jianyu

2014-04-01

123

The integration of the motion equations of low-orbiting earth satellites using Taylor's method  

NASA Astrophysics Data System (ADS)

A method for the numerical integration of the equations of motion for a satellite is proposed, taking the earth's oblateness and atmospheric drag into account. The method is based on Taylor's representation of the solution to the corresponding polynomial system. The algorithm for choosing the integration step and error estimation is constructed. The method is realized as a subrouting package. The method is applied to a low-orbiting earth satellite and the results are compared with those obtained using Everhart's method.

Krivov, A. V.; Chernysheva, N. A.

1990-04-01

124

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

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

125

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

126

An Integrated and Collaborative Approach for NASA Earth Science Data  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

127

[Infrared photostimulated luminescence and optical storage compares in alkaline earth sulphide doped with Mn].  

PubMed

The phosphors SrS: Eu and CaS: Eu doped with Mn were prepared by sulfurization flux method (SFM). Infrared photostimulated luminescence (PSL) of both the phosphors were measured. The PSL peak wavelength of SrS: Eu, Mn is 610 nm. Comparing the storage intensities, SrS has better optical properties. The doping of Mn2+ increases photon amount and improves the storage properties. PMID:16379271

Zhang, Lin; Wang, Yong-sheng; Sun, Li; Lu, Cheng-zhu

2005-09-01

128

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

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. PMID:24616270

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

2014-11-01

129

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

NASA Astrophysics Data System (ADS)

Anatase TiO 2 nanobelts doped with rare earth ( RE) ions Yb 3+, Er 3+ or Yb 3+/Er 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 2, and the Er 3+ or Yb 3+/Er 3+ doped nanobelts show strong visible up-conversion (UC) fluorescence under 980 nm excitation. The UC emission intensity of LTO NBs embedded with Er 3+ or Yb 3+/Er 3+ is slightly higher than that of the corresponding TiO 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.

Ji, Tianhao; Liu, Yang; Zhao, Hui; Du, Haiyan; Sun, Jiayue; Ge, Guanglu

2010-03-01

130

The luminescence properties of the wide bandgap nitrides doped with rare earth ions and gallium nitride doped with conventional isoelectronic impurities  

NASA Astrophysics Data System (ADS)

In this work we study the luminescence properties of GaN, AIN and AlGaN/GaN multiquantum well structure doped with rare earth (RE) ions as well as GaN doped with conventional dopants. The doping method was done through an ion implantation process at room temperature with different ion's doses and implantation energies. The focus was on Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er and Tm ions implanted in GaN epilayers, Eu and Tb ions implanted in crystalline AlN epilayers, Er in situ doped amorphous AlN thin films and AlGaN/GaN multiquantum well structure implanted with Eu ions. It was shown that RE ions embedded in III-nitrides semiconductors followed by post-implantation isochronal thermal annealing at 1100°C in different ambient gases at atmospheric pressure could be activated as efficient luminescence centers. The sharp characteristic emission lines corresponding to RE 3+ intra-4 fn-shell transitions are resolved in spectral range from 350 nm to 1540 nm and observed over the temperature range from 7 K to 330 K. Resulting luminescence was tested by cathodoluminescence (CL), photoluminescence (PL) and luminescence decay kinetics measurements. The fluorescence decay curves of selected transition lines for Pr, Sm, Eu, Tb, Dy, and Er ions implanted in III-nitrides hosts were studied as a function of temperature and analyzed theoretically by applying the Inokuti-Hirayama model. On the basis of recorded spectra, we tabulated emission lines for all investigated RE ions in the GaN epilayers and assigned them to the most probable f-f transitions. In theoretical analyses of experimental results we assume that cation site (Ga, Al) in III-nitride lattice host is the most probable location of implanted RE ions in GaN and AlN and therefore RE ion site symmetry is C3v. For Pr-doped GaN, we have calculated the crystal-field splitting of the multiplet energy levels of Pr3+ (4 f2) using lattice sum models. Furthermore, the model of energy transfers between the host lattice and the RE 4 f n-shell system is presented and discussed in the framework of RE isoelectronic structured trap theory. Moreover, the luminescence properties P, As, and Bi impurities implanted in GaN were investigated by PL and PL excitation spectroscopy. Implanted P, As, and Bi ions in GaN epilayers most probably substitute for N ions and create isoelectronic hole traps in GaN host. On the basis of experimental results and theoretical analysis we have estimated binding energies of exciton bind to P, As, and Bi isoelectronic hole traps. The results indicate that RE doped III-nitrides semiconductors and P, As, and Bi doped GaN epilayer are suitable for visible opt oelectronic devices.

Jadwisienczak, Wojciech M.

131

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

E-print Network

On the optical properties of undoped and rare-earth-doped yttrium aluminium garnet single crystals.1088/0022-3727/45/1/015103 On the optical properties of undoped and rare-earth-doped yttrium aluminium garnet single crystals C R Varney, D aluminium garnets Y3Al5O12 (YAG) are important photonic materials with a wide range of applications

Collins, Gary S.

132

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

133

Eight-wavelength Er-Yb doped amplifier: combiner\\/splitter planar integrated module  

Microsoft Academic Search

We report the successful operation of a pigtailed eight-wavelength planar integrated amplifying combiner. This device can be used in a splitter or in a combiner configuration. It consists in an 8×1 combiner and a 5.5-cm-long Er-Yb doped waveguide amplifier. The module provides net gain simultaneously to the eight combined wavelengths in the 1531-1546-nm optical bandwidth. This module has been incorporated

Y. Jaouen; L. du Mouza; D. Barbier; J.-M. Delavaux; P. Bruno

1999-01-01

134

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

NASA Astrophysics Data System (ADS)

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; Kröll, Stefan; Klieber, Robert; Suter, Dieter

2005-06-01

135

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

136

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

NASA Astrophysics Data System (ADS)

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

Liu, Xianzhu; Fu, Qiang; He, Jingyi

2014-11-01

137

Transforming Water Management: an Emerging Promise of Integrated Earth Observations  

NASA Astrophysics Data System (ADS)

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

Lawford, R. G.

2011-12-01

138

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

139

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

140

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

Microsoft Academic Search

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

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

2004-01-01

141

Non-rare earth white emission phosphor: Ti-doped MgAl2O4  

NASA Astrophysics Data System (ADS)

White emission produced by Ti-doped MgAl2O4 phosphor powder is reported, which is in contrast to blue emission from most Ti-doped single crystals of MgAl2O4. The white emission peak consists of four deconvoluted peaks: 440, 490, 550, and 620 nm, when was excited by 260 nm wavelength. Ti4+ in octahedral sites was found to contribute mostly to greenish blue emissions at 490 and 550 nm. The red emission at 620 nm was produced by abundant Mg2+ and O2- vacancies in the spinel powder.

Lim, J. H.; Kim, B. N.; Kim, Y.; Kang, S.; Xie, R. J.; Chong, I. S.; Morita, K.; Yoshida, H.; Hiraga, K.

2013-01-01

142

Energy transfer in rare earth ion clusters and fluorescence from rare-earth-doped La sub 1. 85 Sr sub 0. 15 CuO sub 4 superconductors  

SciTech Connect

Laser spectroscopy of rare earth ions in solids was used to study mechanisms of non-resonant energy transfer within rare earth clusters, and to detect insulating, impurity phases in rare-earth-doped La{sub 1.85}Sr{sub 0.15}CuO{sub 4} superconductors. The mechanisms of phonon-assisted, non-resonant energy transfer were studied in well-defined dimer sites in Er{sup 3+}:SrF{sub 2} and Pr{sup 3+}:CaF{sub 2}. Application of a magnetic field to Er{sup 3+}:SrF{sub 2} greatly increased the energy-transfer rate. The magnetic field dependence in Er{sup 3+}:SrF{sub 2} indicates that the mechanism of non-resonant energy transfer is a two-phonon, resonant process (Orbach process). Application of a magnetic field to Pr{sup 3+}:CaF{sub 2} had no effect on the energy-transfer rate because no significant Zeeman splittings occurred. The temperature dependence of the energy-transfer rate in Pr{sup 3+}:CaF{sub 2} showed the mechanism to be a one-phonon-assisted process at low temperatures and predominantly an Orbach process above 10 K. In the second part of this thesis, laser spectroscopy of a Eu{sup 3+} probe ion is developed to detect impurity phases in La{sub 1.85}Sr{sub 0.15}CuO{sub 4} superconductors. Two impurity phases were found in polycrystalline La{sub 1.85}Sr{sub 0.15}CuO{sub 4}: unreacted La{sub 2}O{sub 3} starting material, and a La-silicate phase, which formed from contamination during sintering.

Tissue, B.M.

1988-01-01

143

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

E-print Network

the sample is permanently linked to a heat sink. Averaged temperature profiles are obtained by periodic between sample holder and heat sink. The calculated heat capacity was corrected for the contributionsLow-temperature specific heat of rare-earth-doped silicate glasses D. A. van de Straat, J. Baak

Schmidt, Thomas

144

Integrating research infrastructures for solid Earth science in Europe: the European Plate Observing System  

NASA Astrophysics Data System (ADS)

The European Plate Observing System (EPOS) coordinates and integrates the research infrastructures in the European-Mediterranean region, to promote innovative approaches for a better understanding of the physical processes controlling earthquakes, volcanic eruptions, tsunamis as well as those driving tectonics and Earth surface dynamics. The EPOS 30-year plan aims at integrating the currently scattered, but highly advanced European facilities into one distributed, coherent multidisciplinary Research Infrastructure allowing sustainable long-term Earth science research strategies and an effective coordinated European-scale monitoring facility for solid Earth dynamics taking full advantage of new e-science opportunities. EPOS has been approved by ESFRI (the European Scientific Forum for Research Infrastructures) as one of the critical European Research Infrastructures, and the EPOS Preparatory Phase is supported by the European Commission FP7 program. The cooperation between EPOS and similar US infrastructures (i.e. Earthscope) will be ensured by dedicated NSF-EC funding. EPOS is integrating data from permanent national and regional geophysical monitoring networks (seismological, GPS), with the observations from "in-situ" observatories (volcano observatories, in-situ fault zone test sites) and temporary-monitoring and laboratory experiments through a cyber-infrastructure for data mining and processing, and facilities for data integration, archiving and exchange. The vision is to integrate these existing research infrastructures in order to increase the accessibility and usability of multidisciplinary data from monitoring networks, laboratory experiments and computational simulations enhancing worldwide interoperability in Earth Science by establishing a leading integrated European infrastructure and services. More recently the EPOS and the satellite Earth Observation communities are collaborating in order to promote the integration of data from in-situ monitoring networks and remote sensing. The goal is to coordinate the access to data relevant for geohazard research for selected "Supersites" locations in Europe as well as to contribute to the global supersite initiative. Making observations of solid Earth dynamic processes controlling natural phenomena immediately available and promoting their comparison with numerical simulations and their interpretation through theoretical analyses will represent a multidisciplinary platform for discoveries which will foster scientific excellence in solid Earth research. We will present the key actions needed to: i) develop sustainable long-term Earth observation strategies preceding and following earthquakes and volcanic eruptions; ii) develop an innovative integrated e-infrastructure component necessary to create an effective service to users; iii) promote the strategic and outreach actions to meet the specific user needs; iv) develop expertise in the use and interpretation of Supersites data in order to promote capacity building and timely transfer of scientific knowledge. This will facilitate new scientific discoveries through the availability of unprecedented data sets and it will increase resilience and preparedness in the society.

Cocco, M.; Giardini, D.; EPOS-PP Consortium

2011-12-01

145

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

146

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

147

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

148

Superposition-model analysis of rare-earth doped BaY2F8  

NASA Astrophysics Data System (ADS)

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

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

149

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

SciTech Connect

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

Zanatta, A.R.; Ribeiro, C.T.M. [Laboratorio de Filmes Finos, Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, P.O. Box 369, Sao Carlos 13560-250 (Brazil)

2004-12-01

150

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

ERIC Educational Resources Information Center

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

Fox, Justine E.; Glen, Nicole J.

2012-01-01

151

Report on the Development of a Strategic Plan Integrating Earth and Human Systems  

E-print Network

and Human Systems Sustainability in the Academic Teaching, Research and Outreach Activities of MemorialReport on the Development of a Strategic Plan Integrating Earth and Human Systems Sustainability in the Academic Teaching, Research and Outreach Activities of Memorial University of Newfoundland March 2009

Tarasov, Lev

152

Integrated light sources based on self-formed polymer waveguide doped with active medium  

NASA Astrophysics Data System (ADS)

The polymer-based photonic devices have promise as optical components integrated in convenient microchip systems because of ease in the deposition and microfabrication of polymer materials. Furthermore, since the polymers can be easily doped with luminescent materials such as organic dyes, the organic light source devices are also considerable as the integrated optical components. Especially the self-formation method of the fiber type waveguide using the dyedoped photopolymers, called as self-written active (SWA) waveguide technique, brings a simple fabrication scheme of the light sources integrated in the polymer photonic circuit. It has been demonstrated that an in-line optical amplifier and a Fabry-Perot type lasing cavity can be obtained by using the SWA waveguide technique. In this study we have employed this technique to fabricate an incoherent light source with a wideband emission. A serially cascaded SWA waveguide doped with the different organic dyes could be fabricated with a single exposure process. The cascaded SWA waveguide could act as an incoherent light source under UV light irradiation. This device can be expected as a probing light source for the label-free microchip system, which would be available for the biological sensing, environmental measurements, and medical diagnosis.

Sugimoto, S.; Kawaguchi, T.; Yamashita, K.

2012-06-01

153

Nd3+ Doped Fiber Laser With Integrated Acousto-Optic Mode-Locking  

NASA Astrophysics Data System (ADS)

We describe the construction and operation of an FM mode-locked fiber laser using a large-diameter Nd3+ doped silica fiber with dielectric reflectors deposited directly onto the fiber ends and an integrated ZnO acousto-optic phase modulator clamped to the fiber. Optical pulses of less than 60 ps duration have been generated at 432.77 MHz with 400 mW of power to the transducer, and 300-400 ps pulses have been observed with only 4011,W of modulator power, correspond-ing to less than 130 wad of phase modulation.

Howell, Michael D.; Patterson, David B.; Kino, Gordon S.; Khuri-Yakub, Butrus T.; Digonnet, Michel J.

1990-02-01

154

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

PubMed

Luminescent europium (Eu) and dysprosium (Dy) doped yttrium-vanadate (Y-V) nanoparticles (NPs) were synthesized in the cavity of the protein, apoferritin. Y-V NPs were synthesized by incubating a solution of apoferritin with Y(3+) and VO3(-) ions in the presence of ethylene diamine-N-N'-diacetic acid (EDDA). EDDA plays an important role in preventing Y-vanadate precipitation in bulk solution by chelating the Y(3+) ions. Using high resolution electron microscopy, the obtained NPs in the apoferritin cavities were confirmed to be amorphous, and to consist of Y and V. Eu-doped Y-V (Y-V:Eu) NPs were synthesized by the same procedure as Y-V NPs, except that Eu(NO3)3 was added. Y-V:Eu NPs exhibited a strong absorption peak due to the O-V charge transfer transition and remarkable luminescence at 618 nm due to the (5)D0 ? (7)F2 transition. The luminescence lifetime of Y:Eu and Y-V:Eu NPs measured in H2O and D2O solution showed reduction of non-radiative transition to the O-H vibration in Y-V:Eu NPs. Accordingly, Y-V NPs showed strong luminescence compared to Y:Eu NPs. Dy-doped Y-V NPs were also synthesized in apoferritin cavities and showed luminescence peaks at 482 nm and 572 nm, corresponding to (4)F9/2 ? (6)H15/2 and (4)F9/2 ? (6)H13/2 transitions. These NPs stably dispersed in water solution since their aggregation was prevented by the protein shell. NPs encapsulated in the protein are likely to be biocompatible and would have significant potential for biological imaging applications. PMID:24930497

Harada, Tomoaki; Yoshimura, Hideyuki

2014-07-28

155

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

SciTech Connect

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

Fletcher, Luke B.; Witcher, Jon J.; Troy, Neil; Krol, Denise M. [Department of Applied Science, University of California Davis, Davis, California 95616 (United States); Reis, Signo T.; Brow, Richard K. [Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, Missouri 65409 (United States)

2012-07-15

156

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

157

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

SciTech Connect

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

Yang, B.; Townsend, P.D.; Rowlands, A.P. [School of Engineering, University of Sussex, Brighton, BN1 9QH (United Kingdom)] [School of Engineering, University of Sussex, Brighton, BN1 9QH (United Kingdom)

1998-01-01

158

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

159

Optical properties of perfluorocyclobutyl polymers. III. Spectroscopic characterization of rare-earth-doped perfluorocyclobutyl polymers  

NASA Astrophysics Data System (ADS)

We present a continuation of two previous studies [J. Opt. Soc. Am. B 20, 1838 (2003) and J. Opt. Soc. Am. B 21, 958 (2004)] on the optical characteristics of perfluorocyclobutyl-based polymers. Previously, the spectral dependences of the refractive index and the extinction coefficient have been calculated, and investigations were made into the theoretical and measured attenuation spectra of these polymers. Here, we report on the erbium-doped perfluorocyclobutyl aryl ether polymer 1,1,1-tris(4-trifluorovinyloxy)phenyl ethane. The absorption and fluorescence spectra are provided, including the Judd-Ofelt parameterization. The Judd-Ofelt parameters are found to be ?2=16.05×10-20 cm2, ?4=3.67×10-20 cm2, and ?6=3.59×10-20 cm2. These results are compared with those for a similar study on erbium-doped poly(methyl methacrylate), and conclusions are drawn concerning the effect of host properties in the 1550 nm region.

Gordon, Jennifer; Ballato, John; Smith, Dennis W., Jr.; Jin, Jianyong

2005-08-01

160

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

161

Ferrimagnetic Resonance in Rare-Earth Doped Yttrium Iron Garnet. II. Terbium Substitution  

Microsoft Academic Search

The replacement of a small fraction of the yttrium ions in yttrium iron garnet by rare-earth ions produces large effects on the field for ferrimagnetic resonance at low temperatures. Detailed studies have been made on the effect of terbium substitution using concentrations from 0.01 to 0.19 at.%. The variation of the field for resonance as a function of applied field

J. F. Dillon; L. R. Walker

1961-01-01

162

Extruded channel waveguides in a neodymium-doped lead-silicate glass for integrated optic applications  

NASA Astrophysics Data System (ADS)

We report on the development of channel waveguides in a lead-silicate glass through the extrusion technique. An extruded glass slab with four imbedded fibers each with core size of 8 by 2.5 ?m in the horizontal and vertical directions was manufactured. These neodymium-doped channel waveguides were in single-mode operation at 808 nm and had attenuation of 0.1 dB cm-1 at 1.06 ?m. The measured 4F3/2 lifetime of 488 ?s and emission cross section of 2.5×10-20 cm2 were in good agreement with reported values. The integration of multiple glass variants into a single compact platform is presented as a manufacturing route for complex integrated optical waveguides.

Mairaj, Arshad K.; Feng, Xian; Hewak, Daniel W.

2003-10-01

163

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

164

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

165

NIR to visible upconversion in rare-earth Ion-doped NaYF4 crystals  

NASA Astrophysics Data System (ADS)

In this paper we investigate the infrared-to-visible upconversion luminescence in bulk crystals and nanocolloid filled photonic crystal fiber with ytterbium and erbium co-doped NaYF4 upconversion phosphor. The phosphor was prepared by using simple co-precipitation synthetic method. The initially prepared phosphor has very weak upconversion fluorescence. The fluorescence significantly increased after the phosphor was annealed at a temperature of 400°C. Nanocolloids of this phosphor were obtained using water and methanol as solvents and they were utilized as laser filling medium in photonic crystal fibers. Under 980nm laser excitation very strong upconversion signals were obtained at 408 nm, 539 nm and 655 nm. Efficiency and decay life time study of the upconverted emissions was conducted to understand the upconversion mechanisms. The reported nanocolloids are good candidates for fluorescent biosensing applications and also as a new laser filling medium in fiber lasers.

Patel, Darayas; Vance, Calvin; King, Newton; Jessup, Malcolm; Green, Lekara; Sarkisov, Sergey

2010-02-01

166

Rare earth (Sm3+ and Dy3+)-doped gadolinium oxide nanomaterials for luminescence thermometry  

NASA Astrophysics Data System (ADS)

The possibility of using Sm3+- and Dy3+-doped Gd2O3 nanopowders as thermographic phosphor materials was studied. Both samples were synthesized by a combustion method. The crystalline structure of synthesized samples was confirmed by x-ray diffraction measurements. Photoluminescence measurements were recorded in the temperature range from 298 to 773 K. The photoluminescence spectrum of Sm3+ showed peaks that originate from 4G5/2 ? 6HJ transitions, while in the case of Dy3+ 4F7/2 ? 6HJ transitions were observed. The fluorescence intensity ratio of the prepared nanomaterials was studied as a function of temperature using the 4G5/2 ? 6H5/2 and 4G5/2 ? 6H7/2 transitions of Sm3+ ions and the 4F7/2 ? 6H13/2 and 4F7/2 ? 6H15/2 transitions of Dy3+ ions. Both doped Gd2O3 samples proved to have good potential for the development of thermographic phosphors. The maximum sensitivity was approximately 1.744 × 10-3 K-1 for the sample with 1 mol% Sm3+ at 701 K and 2.48 × 10-3 K-1 for the sample with 1 mol% Dy3+ at 773 K. The lifetime measurements were recorded in the same temperature region for the 606 and 572 nm lines of samarium and dysprosium, respectively. The lifetime at room temperature was found to be about 0.395 ms for Sm3+ and 0.123 ms for Dy3+ and it decreased as the temperature increased.

Al-Juboori, Ayad Zwayen M.

2013-11-01

167

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

PubMed

Currently, whether alkaline-earth-doped compounds with electride characteristics are novel candidates for high-performance nonlinear optical (NLO) materials is unknown. In this paper, using quantum chemical computations, we show that: when doping calcium atoms into a family of alkaline-substituted pyridazines, alkaline-earth-based alkaline salt electrides M-H?C?N??Ca (M=H, Li, and K) with distended excess electron clouds are formed. Interestingly, from the triplet to the singlet state, the chemical valence of calcium atom changes from +1 to 0, and the dipole moment direction (??) of the molecule reverses for each M-H?C?N??Ca. Changing pyridazine from without (H?C?N??Ca) to with one alkaline substituent (M-H?C?N??Ca, M=Li and K), the ground state changes from the triplet to the singlet state. The alkaline earth metal doping effect (electride effect) and alkaline salt effect on the static first hyperpolarizabilities (??) demonstrates that (1) the ?? value is increased approximately 1371-fold from 2 (pyridazine, H?C?N?) to 2745au (Ca-doped pyridazine, H?C?N??Ca), (2) the ?? value is increased approximately 1146-fold from 2 in pyridazine (H?C?N?) to 2294au in an Li-substituted pyridazine (Li-H?C?N?), and (3) the ?? value is increased 324-(M=Li) and 106-(M=K) fold from 826 (MLi) and 2294au (MK) to 268,679 (M=Li) and 245,878au (M=K), respectively, from the alkalized pyridazine (M-H?C?N?) to the Ca-doped pyridazine (M-H?C?N??Ca). These results may provide a new means for designing high-performance NLO materials. PMID:24361791

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

2014-02-01

168

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

E-print Network

ERBIUM-DOPED WET OXIDES OF AlGaAs AND InAlP ON GaAs SUBSTRATES FOR OPTOELECTRONIC INTEGRATION;ERBIUM-DOPED WET OXIDES OF AlGaAs AND InAlP ON GaAs SUBSTRATES FOR OPTOELECTRONIC INTEGRATION Abstract of luminescence properties of Erbium ....................................... 3 1.3 Review of Erbium host materials

169

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.

170

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

SciTech Connect

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

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

2007-04-23

171

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

172

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

SciTech Connect

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

Lin, Hang; Chen, Daqin; Niu, Mutong; Yu, Yunlong; Huang, Ping [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Graduate University of Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)] [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Graduate University of Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Wang, Yuansheng, E-mail: yswang@fjirsm.ac.cn [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Graduate University of Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)] [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Graduate University of Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

2010-01-15

173

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

SciTech Connect

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

Sontakke, Atul D.; Annapurna, K. [Glass Science and Technology Section, CSIR-Central Glass and Ceramic Research Institute, 196, Raja S. C. Mullick Road, Kolkata - 700 032 (India)

2012-07-01

174

Upconversion mechanism for two-color emission in rare-earth-ion-doped ZrO2 nanocrystals  

NASA Astrophysics Data System (ADS)

Two-color upconversion (UC) emissions with anomalous power dependence were observed in spectrally tailored rare-earth-ion-doped ZrO2 nanocrystals. Single green and red UC radiation in the visible range was induced by 980nm diode laser excitation in ZrO2:Er3+ and ZrO2:Er3++Yb3+ nanocrystals, yielding quadratic and linear laser power dependences, respectively. The UC spectrum design is enabled by the saturation of the I13/24(Er) state through the efficient energy back-transfer process S3/24(Er)+F7/22(Yb)?I13/24(Er)+F5/22(Yb) induced by high Yb3+ -ion concentration. The anomalous power dependence originates from the fact that the UC rate of the I11/24(Er) state at high Yb3+ -ion concentrations is fundamentally much larger than its decay rate. These conclusions obtained are confirmed by theoretical investigations based on steady-state rate equations.

Chen, Guanying; Somesfalean, Gabriel; Liu, Yan; Zhang, Zhiguo; Sun, Qiu; Wang, Fuping

2007-05-01

175

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

176

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

PubMed

Upconversion of infrared light to visible light has important implications for bioimaging. However, the small absorption cross-section of rare earth dopants has limited the efficiency of these anti-Stokes nanomaterials. We present enhanced excitation absorption and single particle fluorescent emission of sodium yttrium fluoride, NaYF4: Yb, Er based upconverting nanoparticles coated with a gold nanoshell through surface plasmon resonance. The single gold-shell coated nanoparticles show enhanced absorption in the near infrared, enhanced total emission intensity, and increased green relative to red emission. We also show differences in enhancement between single and aggregated gold shell nanoparticles. The surface plasmon resonance of the gold-shell coated nanoparticle is shown to be dependent on the shell thickness. In contrast to other reported results, our single particle experimental observations are corroborated by finite element calculations that show where the green/red emission enhancement occurs, and what portion of the enhancement is due to electromagnetic effects. We find that the excitation enhancement and green/red emission ratio enhancement occurs at the corners and edges of the doped emissive core. PMID:25517688

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

2015-01-16

177

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

Microsoft Academic Search

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

A. Corsini

2009-01-01

178

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

179

Structural and magnetic properties of rare-earth doped (Sr 2-xSm x)FeMoO 6 compounds  

NASA Astrophysics Data System (ADS)

Electron doped double perovskite compound (Sr 2-xSm x)FeMoO 6 (0? x?0.25) has been synthesized by solid-state reaction at high temperature. Crystal structure and magnetic properties of the compounds have been investigated by X-ray powder diffraction (XRD) and magnetic measurements. XRD revealed that all the compounds were of single phase and belonged to a I4/m lattice. The degree of cationic ordering on the B site was decreased pronouncedly by the electron doping. Different from the results of La- and Nd-doped Sr 2FeMoO 6, Curie temperature ( TC) of (Sr 2-xSm x)FeMoO 6 decreased first with the doping and then increased beyond x=0.15, indicating that steric effect was enhanced as the radius of rare-earth ions decreased. Saturation magnetization ( MS) of the compounds decreased with the doping level and anti-site (AS) concentration. Sm moment showed a considerable contribution to MS at low temperature, leading to an abrupt drop of MS between x=0.1 and 0.15.

Zhang, Q.; Liu, G. Y.; Xu, Z. F.; Feng, X. M.; Rao, G. H.

2010-03-01

180

Ultraviolet direct printing of rare-earth-doped polymer waveguide amplifiers  

SciTech Connect

Polymer channel waveguide amplifier arrays were fabricated using ultraviolet direct printing methodology. The effects of different weight percentage (wt. %) combinations of rare-earth ions erbium (Er{sup 3+}) and ytterbium (Yb{sup 3+}) on the absorption spectrum, as well as the internal gain, were investigated. With an input signal power of {approx}-18 dBm, the highest internal gain obtained is {approx}16.5 dB at a wavelength of 1533 nm for a 20 mm long multimode channel waveguide codoped with {approx}1 wt. % of Er{sup 3+} and {approx}10 wt. % of Yb{sup 3+} derivatives. The UV direct printing methodology opens a simple platform for the fabrication of dense and compact polymer waveguide laser arrays.

Wong, W.H.; Chan, K.S.; Pun, E.Y.B. [Department of Electronic Engineering and Department of Physics and Material Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Department of Physics and Material Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Department of Electronic Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)

2005-07-04

181

Correlation of XANES features with the scintillation efficiencies of Ce doped alkaline earth lithium silicate glasses  

SciTech Connect

Cerium-activated, lithium-silicate glasses are widely used as thermal neutron detectors because of their versatility, robustness and low cost. The glasses convert the energy of the neutrons to visible light pulses that may be counted. This process, scintillation, is generally thought to be composed of three steps: ionization, energy transfer, and luminescence. If defects are present, they can trap the excitations, altering the scintillation output. These features have been discussed previously. The presence of magnesium in these glasses increases scintillation efficiency, but as previously observed the effect drops by a factor greater than 2.5 with substitution through the series of alkaline earths. Here, cerium activated glasses of composition 20Li{sub 2}O{center_dot}15MO{center_dot}64.4SiO{sub 2}{center_dot}0.6Ce{sub 3}O{sub 3} (where m is Mg, Ca, Sr, or Ba) exhibit scintillation efficiencies that vary by more than a factor of 2.5 with the alkaline earth. Previous work has suggested a correlation between the microstructure of these glasses and scintillation efficiency. Measurements of the Ce L{sub III} x-ray absorption edge in the Mg, Ca and Sr glasses display a feature near the absorption edge that is suggestive of the presence of Ce{sup 4+}. The area of this peak is, in fact, correlated with the scintillation efficiency of the glass. The amount of Ce{sup 4+} indicated by the intensity of this feature is, however, too high to be a permanent population. The authors suspect that the feature is a transient phenomenon related to creation of Ce{sup 4+} and trapped electrons due to photoionization by the x-ray beam.

Blanchard, D.L.; Sunberg, D.S.; Craig, R.A.; Bliss, M. [Pacific Northwest Lab., Richland, WA (United States); Weber, M.J. [Lawrence Livermore National Lab., CA (United States)

1994-11-01

182

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

E-print Network

, and blue wavelengths from GaN doped with Eu, Er, and Tm has led to the development of flat-panel display are dis- cussed, along with techniques for multicolor integration. Visible emission at red, green elements in solid-state lasers (for example the Nd:YAG laser) and in phosphors for color lamps and displays

Steckl, Andrew J.

183

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

NASA Astrophysics Data System (ADS)

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

Collins, W. D.; Craig, A. P.; Truesdale, J. E.; Di Vittorio, A. V.; Jones, A. D.; Bond-Lamberty, B.; Calvin, K. V.; Edmonds, J. A.; Kim, S. H.; Thomson, A. M.; Patel, P.; Zhou, Y.; Mao, J.; Shi, X.; Thornton, P. E.; Chini, L. P.; Hurtt, G. C.

2015-01-01

184

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

185

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

186

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

ERIC Educational Resources Information Center

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

Mathar, Reiner

2010-01-01

187

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

SciTech Connect

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

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

2012-06-10

188

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

189

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

NASA Astrophysics Data System (ADS)

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 between other third party applications. For this purpose, the common interfaces of earth system models can be standardized and also self-describing modeling systems can be built to increase interoperability between models and third party applications such as workflow systems, metadata/data portals, web services and scientific gateways. Fortunately, many efforts are currently underway to create standardized and easy to use multi-component earth system models and their applications such as Earth System Curator and Earth System Framework (ESMF). In this study, it is presented and analyzed a new methodology to combine scientific workflow and modeling framework approach together to create a standardized work environment. The methodology uses the ESMF library to create and self-describing and standardized coupled modeling systems and Kepler scientific workflow application to integrate modeling system to a workflow environment. The proposed methodology is tested using two typical and realistic earth system modeling application. The results of example workflows that are based on the proposed methodology are a part of this study. The first example allows running and analyzing a global circulation model on both a grid computing environment (TeraGrid) and a cluster system with meaningful abstraction of used model and computing environment. The development version of NCAR Community Climate System Model (CCSM4) model is used for this purpose. In this application example, the collection of provenance information has the added benefit of documenting a run in far greater detail than before. This facilitates exploration of runs and leads to possible reproducibility. In second example, a regional coupled climate modeling system (WRF and ROMS) is developed for Mediterranean region and integrated into workflow system to provide better representation of regional climate system. This application has curial importance in downscaling output of the global circulation models over Turkey and near regions and it also can be used to create better representation of regional climate for the future scenarios. As, in the first application example, the workflow application collects provenance information automatically from the coupled earth system modeling system to reproduce, compare and debug the results. The results show that the developed workflow environment is capable of running different earth system models on a different high performance computing resource with a meaningful abstraction. The proposed work environment acts as an abstraction layer and hides the detail of the used infrastructure and earth system model from user and it also collect standardized provenance information about both model and computing resource to represent the work environment as possible as it can.

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

2010-05-01

190

56.6 DB High Gain L-Band Edfa Utilizing Short-Length Highly-Doped Erbium Rare-Earth Material  

NASA Astrophysics Data System (ADS)

In this paper, we experimentally investigate the performance of an efficient high gain L-band erbium-doped fiber (EDF) amplifier structure utilizing short-length highly-doped erbium rare-earth material with a single pump source. The amplifier gain and noise figure variation for different amplifier structures have been investigated. A filter is used to reduce the self-saturation effect and suppress the C-band amplified spontaneous emission (ASE) noise. The amplifier achieves a signal gain of 56.6 dB with a low noise figure of 4.8 dB at -50 dBm input signal power using only 8 m of EDF length. The amplifier gain shows significant improvement of 6 dB with C/L band coupler and 13 dB with tunable-band pass filter compared to amplifier structure without ASE suppression.

Al-Mansoori, M. H.; Al-Ghaithi, W. S.

2014-07-01

191

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

192

Effects of rare earth elements substitution for Ti on the structure and electrochemical properties of a Fe-doped Ti–V-based hydrogen storage alloy  

Microsoft Academic Search

Effects of a partial substitution of rare-earth elements of Y, La, Ce, Pr, Nd in an atom fraction of 1\\/8 for Ti on the structure and electrochemical property of a Fe-doped Ti–V-based hydrogen storage alloy, Ti0.8Zr0.2V2.7Mn0.5Cr0.6Ni1.25Fe0.2, have been investigated systematically using X-ray diffraction, scanning electron microscope, energy dispersive spectroscope and electrochemical tests including charge\\/discharge, high rate dischargeability, polarization, etc. The

Mingxia Gao; He Miao; Yu Zhao; Yongfeng Liu; Hongge Pan

2009-01-01

193

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

194

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

195

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

NASA Astrophysics Data System (ADS)

NASA plays a leadership role in the world of Advanced Information Technologies. Part of our mission is to leverage those technologies to increase the usability of the growing amount of earth observation produced by the science community. NASA World Wind open source technology provides a complete 3D visualization platform that is being continually advanced by NASA, its partners and the open source community. The technology makes scientific data and observations more accessible to Earth scientists and offers them a standards-based extensible platform to manipulate and analyze that data. The API-centric architecture of World Wind's SDK allows others to readily extend or embed this technology (including in web pages). Such multiple approaches to using the technology accelerate opportunities for the research community to provide "advances in fundamental understanding of the Earth system and increased application of this understanding to serve the nation and the people of the world" (NRC Decadal Survey). The opportunities to advance this NASA Open Source Agreement (NOSA) technology by leveraging advances in web services, interoperability, data discovery mechanisms, and Sensor Web are unencumbered by proprietary constraints and therefore provide the basis for an evolving platform that can reliably service the needs of the Earth Science, Sensor Web and GEOSS communities. The ability for these communities to not only use this technology in an unrestricted manner but to also participate in advancing it leads to accelerated innovation and maximum exchange of information. 3 characteristics enable World Wind to push the frontier in Advanced Information Systems: 1- World Wind provides a unifying information browser to enable a variety of 3D geospatial applications. World Wind consists of a coherent suite of modular components to be used selectively or in concert with any number of programs. 2- World Wind technology can be embedded as part of any application and hence makes it more possible to include virtual globe capability in support of any Earth science objective. 3- With the source code being fully accessible, anyone can advance this technology (including in a commercial or other proprietary manner). Such features enable World Wind to provide easy discovery, access and 3D integration/visualization/analysis of Earth observation data in a flexible, customizable open source tool. This positions World Wind to become a key part of an Advanced Information Systems infrastructure supporting a collaborative decision-making environment for a variety of applications.

Alameh, N.; Hogan, P.

2008-12-01

196

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

197

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

198

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

NASA Astrophysics Data System (ADS)

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

Wang, Yansen; Huynh, Giap; Williamson, Chatt

2013-12-01

199

Integrated C-band erbium-doped fiber amplifier and dispersion compensation module with negligible pump power penalty.  

PubMed

Conventional dispersion compensation requires erbium-doped fiber amplifiers with high pump power to compensate for excess losses introduced by the dispersion-compensating fiber. We report and demonstrate an optimized single-pump amplifier configuration with a pump power penalty of less than 5% when integrated with a fiber Bragg grating dispersion compensator. The system is capable of compensating 100 km of G.652 single-mode fiber. PMID:19881651

Varghese, Samuel; Blixt, Peter; Darby, David; Nair, Suresh

2009-11-01

200

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

201

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

202

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

PubMed

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

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

2015-02-25

203

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

204

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

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

205

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

NASA Astrophysics Data System (ADS)

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

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

2003-08-01

206

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

207

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

NASA Astrophysics Data System (ADS)

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

Farahanifar, Mohammad; Assadian, Nima

2015-01-01

208

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

SciTech Connect

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

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

2010-01-01

209

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

210

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

211

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

SciTech Connect

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

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

2014-01-28

212

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

213

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

214

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

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

215

Growth, characterization and luminescence and optical properties of rare-earth elements and transition metals doped in wide bandgap nitride semiconductors  

NASA Astrophysics Data System (ADS)

Rare-earth element and transition metals doped AlN, GaN and BN films were successfully grown using reactive magnetron sputtering. The structural, optical and luminescence properties of these nitride films were then studied using Scanning Electron Microscopy, X-rays diffraction, Cathodoluminescence and Tube furnace. Both amorphous and crystalline films were obtained depending on the substrate temperature during the deposition. Cryogenically grown amorphous films were the principal focus of this research. The substrate were cooled using liquid nitrogen during the growth and pure amorphous films were obtained. Crystalline films were also obtained using an electric heater to keep substrates at high temperature. X-ray diffraction analysis was used to confirm the structure of films. Rare-earth elements Ho, Gd, Pr, Tm and Sm and transition metals W and Y were doped into the nitride films by co-sputtering. The optical and luminescence properties of these nitride materials were studied using Cathodoluminescence. Characteristic light emissions related to these Ho+3, Gd +3, Pr+3, Tm+3, Sm+3, W+3 and Y+3 ions were observed. The results show the suitability of these materials for potential applications of light-emitting devices. Luminescence enhancement in the nitride materials was studied by co-doping Gd with Ho, Pr, Sm and W in nitride materials. Stripes of these materials were also prepared and studied for luminescence enhancement. It was observed that not only the presence of Gd but also some interference phenomena enhance luminescence in these materials. More than 100% enhancement in luminescence shows that these techniques used for luminescence enhancement are successful and useful for future applications. Stopping power of AlN for electrons and depth penetration of electron were studied by making bilayers of AlN doped with Tm+3 and Ho+3 ions. Electron beams of different energies were allowed to penetrate in the known thickness of the AlN:Tm/AlN:Ho bilayer. Stopping power of AlN was calculated using the numerical values of the energies of electron beams and the thickness of the bilayers.

Maqbool, Muhammad

216

Creation of integrated analytical GIS-system on the Earth Sciences  

NASA Astrophysics Data System (ADS)

The program-technological complex is created on the basis of integrated geoinformation systems (GIS) as which are understood as three dimensional representations of various earths' layers in vector and raster form with the variable dimension. For the management, the distributed access and data processing of such volume the system of meta-computing GRID is used. For a prototype of meta-computing GRID environment the Globes system will be conducted, which is created and used in leading US scientific and computing centers. Execution and analysis of proposed model will be realized by parallel program, written by high-level language with MPI (Message Parsing Interface) using. This parallel program will be executed with user's parameters corresponding to requirements of modern computing clusters. Network components of parallel access and preview of data will be realized in the framework of multi-level model of the corporative server software and J2EE www-service, advanced by Sun Microsystems. At each investigation phase the user carries out processing and multimedia visualization of the received results in time in two and three-dimensional space. The developed multiplanimetric geoinformation system will allow to carry out the integrated analysis of geoinformation streams in an interactive mode, in particular, to reveal laws of existential distribution and dynamics of development of the basic structural lithosphere's elements, and also to establish relationship of stages of their development with epoch of formation of large and superlarge mineral deposits. Funded by RFBR (grants 02-07-90140 and 04-07-90304).

Ryakhovsky, V.; Aladyshev, O.; Shulga, N.

2004-12-01

217

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

Microsoft Academic Search

Currently, many large geoscientific efforts (e.g., EarthScope, Continental Dynamics, and GeoSwath) have emphasized that a crucial need in advancing our understanding of the structure and evolution of the continents is high-resolution, 3-D models of lithospheric structure. In addition, the geoscience community recognizes that our ultimate goal is the addition of the dimension of time to make the problem 4-D. Adding

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

2008-01-01

218

Gold catalysts supported on ceria doped by rare earth metals for water gas shift reaction: Influence of the preparation method  

Microsoft Academic Search

Gold catalysts based on ceria, doped by various RE metals (La, Sm, Gd, Yb, Y) were studied. The influence of the preparation methods on structure, properties and catalytic activity in the WGS reaction was investigated. The catalysts’ supports were prepared using two different methods: co-precipitation (CP) and mechanochemical activation (MA). The catalysts were tested in a wide temperature interval without

D. Andreeva; I. Ivanov; L. Ilieva; M. V. Abrashev; R. Zanella; J. W. Sobczak; W. Lisowski; M. Kantcheva; G. Avdeev; K. Petrov

2009-01-01

219

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

220

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.

221

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

SciTech Connect

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

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

2014-01-01

222

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

223

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

224

Micromolding in capillaries for calcination-free fabrication of flexible inorganic phosphor films consisting of rare-earth-ion-doped nanoparticles.  

PubMed

We discuss the micromolding in capillaries technique for the direct fabrication of calcination-free rare earth ion-doped (RE) phosphor films consisting of RE nanoparticles on plastic sheets. We synthesized two types of RE nanoparticles consisting of Y2O3 matrix doped with Er and Yb ions. Green upconversion luminescence, red upconversion luminescence, and near-infrared fluorescence appeared from the RE nanoparticles under excitation of near-infrared light. Adjusting the channel width and depth of polydimethylsiloxane molds led to control of the density of nanoparticles in the patterned RE nanoparticle films. Adjusting concentration of the RE nanoparticle dispersion and size of the RE nanoparticles allowed for the control of the density of nanoparticles in the patterned RE nanoparticle films. The density of nanoparticles in the patterned RE films on plastic sheets increased with an increase in the number of injection and drying of the RE nanoparticle dispersion. These results demonstrate that this technique enables us to directly fabricate the patterned RE phosphor films on plastic sheets, leading to the fabrication of inorganic flexible devices with small fabrication steps and material consumptions. PMID:23968436

Watanabe, Satoshi; Asanuma, Takeo; Hyodo, Hiroshi; Soga, Kohei; Matsumoto, Mutsuyoshi

2013-09-01

225

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

NASA Astrophysics Data System (ADS)

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

Liu, Yunxin; Xu, Changfu; Yang, Qibin

2009-04-01

226

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.

227

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

228

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

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

229

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

NASA Astrophysics Data System (ADS)

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

Enloe, Y.; Yapur, M.

2011-12-01

230

Path-integral approach to the electron density of states at the interface of a single modulation-doped heterojunction  

NASA Astrophysics Data System (ADS)

The electronic density of states (DOS) at the interface of a single modulation-doped heterojunction is calculated both in the fluctuation band tail and in the semiclassical limit using the path-integral method. Due to charge density inhomogeneities in the heavily doped barrier region, random potential fluctuations are generated in whose minima carriers are localized, resulting in a band-tail density spectrum. The screening of the long-range potential fluctuations, which are important for the problem considered, is accounted for by using the two-dimensional Thomas-Fermi model. The statistical properties of the random impurity charge distribution are taken into account using the binary correlation function of the random potential for the specific geometry of the problem in two limiting cases of the general correlation function. Analytical expressions for the dimensionless functions of the exponential and preexponential of the band-tail DOS, as a function of the energy, are obtained in the weak and strong screening limit for the quasi-2D case under consideration and are compared to the respective functions for the general d-dimensional case. The dependence of the band-tail DOS behavior on the relevant parameters of the system, namely, spacer layer thickness, doping layer thickness, 2D EG thickness, and 3D-impurity concentration is studied numerically for AlxGa1-xAs-GaAs modulation doped heterostructures and numerical results for the 2D-DOS are presented. The band-tail results for the 2D-DOS are compared with the Kane approximation derived by taking the limit t-->0 in order to determine ?(E) in the whole energy range. We compare the results from the two computed cases of the path-integral expression for the DOS corresponding to the two limits of the general correlation function with each other. On the other hand, we compare the semiclassical limit and the white Gaussian noise limit of the above results with many other theoretical methods such as the generalized semiclassical method, multiple scattering method and the simulations resulting from the tight-binding model.

Sa-Yakanit, V.; Slavcheva, G.

1998-11-01

231

Fabrication and characterization of PECVD phosphorus-doped silicon oxynitride layers for integrated optics applications  

Microsoft Academic Search

Phosphorus-doped silicon oxynitride layers (n = 1.48 – 1.59) have been deposited by a Plasma Enhanced Chemical Vapor Deposition (PECVD) process from 2% SiH4\\/N2, N2O, NH3 and PH3 gaseous mixtures. The refractive indices of the deposited layers were found to increase by adding PH3 gas to the process. A slight variation in refractive index was observed in low refractive indices

M. G. Hussein; K. Wörhoff; G. Sengo; A. Driessen; A. Devi; H. Parala; M. L. Hitchman; R. Fischer; M. D. Allendorf

2004-01-01

232

Anisotropy of the Hopping Integrals of Calcium Doped Yttrium Iron Garnet  

Microsoft Academic Search

\\u000a The main objective of this paper is to indicate a possible origin of strong magnetic anisotropy of the electric resistance\\u000a in calcium-doped yttrium-iron garnets (Ca : YIG). Recent measurements of the electric resistance of the as-grown Ca : YIG\\u000a samples show strong anisotropy connected with differ- ent orientations of the applied magnetic field with respect to the electric\\u000a current. The

A. Lehmann-Szweykowska; R. J. Wojciechowski; J. Barna?; P. E. Wigen

233

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

234

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

235

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

NASA Astrophysics Data System (ADS)

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

Nolan, M.

2004-12-01

236

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

237

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

NASA Astrophysics Data System (ADS)

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

Herbster, Adolfo F.; Romero, Murilo A.

2014-09-01

238

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

239

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

NASA Astrophysics Data System (ADS)

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 data sets that are acquired at high cost, particularly in the marine environment, and that contain irreplaceable observations made of earth’s dynamic properties. The Marine Geoscience Data System (MGDS, www.marine-geo.org) and the Geoinformatics for Geochemistry Program (GfG, www.geoinfogeochem.org) have over the past decade developed, maintained, and operated community-driven data collections that support the preservation, discovery, retrieval, and analysis of a wide range of observational field and analytical data types from the marine and terrestrial environments, among them the PetDB database, the EarthChem data network, the Ridge2000 and MARGINS databases, the Antarctic and Southern Ocean Data System (ASODS), the Global Multi Resolution Topography Synthesis, and the System for Earth Sample Registration (SESAR). MGDS and GfG systems have been developed based on an active understanding of the practices, needs, and concerns of their user communities. They have engaged investigators in the design of the systems, seeking their feedback, and educating the community about responsibilities and benefits of scientific data management and sharing, and worked with funding agencies, editors, publishers, professional societies, and researchers to achieve broad community support, to proactively drive the development of community standards and best practices for data submission, data publication, data documentation, and data archiving, and to advance implementation. In a new formal partnership named IEDA (Integrated Earth Data Applications), the MGDS and GfG will be funded by the US National Science Foundation under a Cooperative Agreement to continue the operation of all MGDS and GfG data systems, while providing new integrated data services that will substantially enhance the utility of all data collection components, and improve data curation, interoperability and efficiency of operations. These will include an on-line service to improve ease of data submission across our user communities, a data publication service for scientists to publish their datasets with citable universal identifiers (DOIs), partnerships with institutions to ensure long-term archiving of data holdings, an authentication service for single sign-on to all systems, and operational services for shared vocabularies and to ease registration of common expeditions and geochemical datasets across our two systems.

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

2010-12-01

240

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

241

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

242

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

243

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

244

Optical properties of macroporous Y 3Al 5O 12 crystals doped with rare earth ions synthesized via sol-gel process from ionic precursors  

NASA Astrophysics Data System (ADS)

We have prepared macroporous Y 3Al 5O 12 (YAG) monoliths doped with rare earth (RE) ions (RE = Ce, Eu, Sm, and Pr) via the ionic precursor-derived sol-gel reaction accompanied by phase separation and investigated their fluorescence and scattering properties. YAG monoliths with well-defined bicontinuous macropores and skeletons were synthesized from the mixture of water and ethanol containing yttrium(III), aluminum(III), and RE(III) salts using propylene oxide as a gelation initiator and poly(ethylene oxide) as a phase separation inducer. X-ray diffraction measurements reveal that the sample as-dried and that heat-treated at 700 °C are amorphous, while a single crystalline phase of YAG is precipitated in the samples heat-treated at temperatures between 800 and 1100 °C. The macroporous YAG:RE ceramics heat-treated at 800 °C and higher temperatures exhibit fluorescence due to 4f-5d (Ce 3+) and 4f-4f (Eu 3+, Sm 3+, Pr 3+) electronic transitions characteristic of the RE ions occupying the eight-coordinated dodecahedral sites in YAG lattice. Coherent backscattering experiments indicate that the scattering strength is enhanced by the densification of skeletons in macroporous YAG monoliths, depending on the heat treatment temperature.

Murai, Shunsuke; Fujita, Koji; Iwata, Koji; Tanaka, Katsuhisa

2010-12-01

245

Thermal activation, cathodo- and photoluminescence measurements of rare earth doped (Tm, Tb, Dy, Eu, Sm, Yb) amorphous/nanocrystalline AlN thin films prepared by reactive rf-sputtering  

NASA Astrophysics Data System (ADS)

We present comprehensive cathodo- and photoluminescence measurements from thin amorphous/nanocrystalline (a/nc-) AlN films doped with rare earths. The (a/nc-) AlN films were prepared by reactive rf-sputtering using a high purity (5 N) aluminium disk in high purity nitrogen atmosphere (5 N, pressure ca. 1.3 mbar). The rare earth doping (Tm, Tb, Dy, Eu, Sm, Yb, concentrations were below 1%) was performed by placing respective rare earth metal pieces of appropriate size onto the aluminium disk. The rare earth ion emissions cover the blue (Tm), green (Tb), yellow (Dy), red (Sm, Eu) and infrared (Yb). The optical and related structural properties of the films are correlated by means of high resolution transmission electron microscopy in combination with cathodoluminescence measurements in a scanning electron microscope. In addition, the corresponding compositions are determined by energy-dispersive X-ray analysis. The cathodo- and photoluminescence spectra of the rare earth 3+ ions are recorded in the visible at 300 K in the as-grown condition (Tm, Tb, Dy, Sm, Eu, Yb) and after annealing treatments in the temperature range from 300 to 1100 °C by steps of 150 °C (Tb, Sm, Eu, Yb). The anneal-related changes in the cathodo- and photoluminescence emission spectra and in the microstructure of the films are addressed. The AlN films show nanocrystalline structure almost independent of the annealing treatment. Optimal annealing temperature for emissions of Sm and Eu doped (a/nc-) AlN were derived to be 900 °C whereas Tb 3+ and Yb 3+ emissions increase at least up to 1100 °C.

Weingärtner, R.; Erlenbach, O.; Winnacker, A.; Welte, A.; Brauer, I.; Mendel, H.; Strunk, H. P.; Ribeiro, C. T. M.; Zanatta, A. R.

2006-05-01

246

Enhanced 1.53-?m and lowered upconversion luminescence in Er3+-doped Ga2O3-GeO2-Bi2O3-Na2O glass by codoping rare earths  

NASA Astrophysics Data System (ADS)

Spectroscopic properties and energy transfer (ET) in Ga2O3-GeO2-Bi2O3-Na2O (GGBN, glass doped with Er3+ and rare earths (RE3+; RE3+=Ce3+, Tb3+) have been investigated. Intense 1.53-?m emission with the peak emission cross-section achieved to 7.58×10-21 cm2 from Er3+-doped GGBN glass has been obtained upon excitation at 980 nm. Effects of RE3+ (RE3+=Ce3+, Tb3+) codoping on the optical properties of Er3+-doped GGBN glass have been investigated and the possible ET mechanisms involved have also been discussed. Significant enhancement of the 1.53 ?m emission intensity and decrease of upconversion (UC) fluorescence with increasing Ce3+ concentration have been observed. The incorporation of Tb3+ into Er3+-doped GGBN glass could significantly decrease the UC emission intensity, but meanwhile decrease the 1.53 ?m emission intensity due to the ET from Er3+:4I13/2 to Tb3+:7F2. The results indicate that the incorporation of Ce3+ into Er3+-doped GGBN glass can effectively improve 1.53-?m and lower UC luminescence, which makes GGBN glass more attractive for use in C-band optical fiber amplifiers.

Shi, D. M.; Zhao, Y. G.; Wang, X. F.

2011-07-01

247

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

248

Use of Persistent Identifiers to link Heterogeneous Data Systems in the Integrated Earth Data Applications (IEDA) Facility  

NASA Astrophysics Data System (ADS)

The Integrated Earth Data Applications (IEDA) facility maintains multiple data systems with a wide range of solid earth data types from the marine, terrestrial, and polar environments. Examples of the different data types include syntheses of ultra-high resolution seafloor bathymetry collected on large collaborative cruises and analytical geochemistry measurements collected by single investigators in small, unique projects. These different data types have historically been channeled into separate, discipline-specific databases with search and retrieval tailored for the specific data type. However, a current major goal is to integrate data from different systems to allow interdisciplinary data discovery and scientific analysis. To increase discovery and access across these heterogeneous systems, IEDA employs several unique IDs, including sample IDs (International Geo Sample Number, IGSN), person IDs (GeoPass ID), funding award IDs (NSF Award Number), cruise IDs (from the Marine Geoscience Data System Expedition Metadata Catalog), dataset IDs (DOIs), and publication IDs (DOIs). These IDs allow linking of a sample registry (System for Earth SAmple Registration), data libraries and repositories (e.g. Geochemical Research Library, Marine Geoscience Data System), integrated synthesis databases (e.g. EarthChem Portal, PetDB), and investigator services (IEDA Data Compliance Tool). The linked systems allow efficient discovery of related data across different levels of granularity. In addition, IEDA data systems maintain links with several external data systems, including digital journal publishers. Links have been established between the EarthChem Portal and ScienceDirect through publication DOIs, returning sample-level objects and geochemical analyses for a particular publication. Linking IEDA-hosted data to digital publications with IGSNs at the sample level and with IEDA-allocated dataset DOIs are under development. As an example, an individual investigator could sign up for a GeoPass account ID, write a proposal to NSF and create a data plan using the IEDA Data Management Plan Tool. Having received the grant, the investigator then collects rock samples on a scientific cruise from dredges and registers the samples with IGSNs. The investigator then performs analytical geochemistry on the samples, and submits the full dataset to the Geochemical Resource Library for a dataset DOI. Finally, the investigator writes an article that is published in Science Direct. Knowing any of the following IDs: Investigator GeoPass ID, NSF Award Number, Cruise ID, Sample IGSNs, dataset DOI, or publication DOI, a user would be able to navigate to all samples, datasets, and publications in IEDA and external systems. Use of persistent identifiers to link heterogeneous data systems in IEDA thus increases access, discovery, and proper citation of hard-earned investigator datasets.

Hsu, L.; Lehnert, K. A.; Carbotte, S. M.; Arko, R. A.; Ferrini, V.; O'hara, S. H.; Walker, J. D.

2012-12-01

249

Gamma ray spectroscopy employing divalent europium-doped alkaline earth halides and digital readout for accurate histogramming  

DOEpatents

A scintillator radiation detector system according to one embodiment includes a scintillator; and a processing device for processing pulse traces corresponding to light pulses from the scintillator, wherein pulse digitization is used to improve energy resolution of the system. A scintillator radiation detector system according to another embodiment includes a processing device for fitting digitized scintillation waveforms to an algorithm based on identifying rise and decay times and performing a direct integration of fit parameters. A method according to yet another embodiment includes processing pulse traces corresponding to light pulses from a scintillator, wherein pulse digitization is used to improve energy resolution of the system. A method in a further embodiment includes fitting digitized scintillation waveforms to an algorithm based on identifying rise and decay times; and performing a direct integration of fit parameters. Additional systems and methods are also presented.

Cherepy, Nerine Jane; Payne, Stephen Anthony; Drury, Owen B; Sturm, Benjamin W

2014-11-11

250

Monolithic integration of erbium-doped amplifiers with silicon-on-insulator waveguides.  

PubMed

Monolithic integration of Al2O3:Er3+ amplifier technology with passive silicon-on-insulator waveguides is demonstrated. A signal enhancement of >7 dB at 1533 nm wavelength is obtained. The straightforward wafer-scale fabrication process, which includes reactive co-sputtering and subsequent reactive ion etching, allows for parallel integration of multiple amplifier and laser sections with silicon or other photonic circuits on a chip. PMID:21197045

Agazzi, Laura; Bradley, Jonathan D B; Dijkstra, Meindert; Ay, Feridun; Roelkens, Gunther; Baets, Roel; Wörhoff, Kerstin; Pollnau, Markus

2010-12-20

251

Mitochondrial potential (??m changes in single rat hepatocytes: The effect of orthovanadate nanoparticles doped with rare-earth elements.  

PubMed

Rare-earth-based nanoparticles (NPs) are widely used as fluorescent probes for imaging in vitro and in vivo. One of the challenges that restrain NPs applications in biomedical research is their effect on subcellular structures. In this paper, the ability of lanthanide NPs to affect the cellular oxidative balance and alter the mitochondrial function was analyzed. Since size and shape mutually affect the cellular internalization and intracellular distribution of NPs, the investigations were performed with NPs of spherical (GdYVO4:Eu(3+), spindle-(GdVO4: Eu(3+) and rod-like (LaVO4: Eu(3+) shapes. Quantitative microfluorimetry with JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine iodide) as a mitochondrial probe was used for monitoring of the mitochondrial transmembrane potential (?? m) in single living cells. Changes in the ratio of the JC-1 probe fluorescence were used to analyze the NPs effect on ?? m. The fastest suppressive effect (within 1 hour) was found for spherical NPs. Gradual lowering of ?? m was observed at the exposure of cells within 24 hours for all types of NPs. Exogenous thiols were required for ?? m protection. The protective role of exogenous glutathione (GSH) proves that the increase of reactive oxygen species (ROS) formation with depletion of GSH can mediate NPs toxicity. The dynamics of the shape-dependent effect can be explained by the features of NPs transportation into cells. PMID:25533054

Kavok, Nataliya S; Averchenko, Katherine A; Klochkov, Vladimir K; Yefimova, Svetlana L; Malyukin, Yuri V

2014-12-01

252

Enhancement of Cerenkov Luminescence Imaging by Dual Excitation of Er3+, Yb3+-Doped Rare-Earth Microparticles  

PubMed Central

Cerenkov luminescence imaging (CLI) has been successfully utilized in various fields of preclinical studies; however, CLI is challenging due to its weak luminescent intensity and insufficient penetration capability. Here, we report the design and synthesis of a type of rare-earth microparticles (REMPs), which can be dually excited by Cerenkov luminescence (CL) resulting from the decay of radionuclides to enhance CLI in terms of intensity and penetration. Methods: Yb3+- and Er3+- codoped hexagonal NaYF4 hollow microtubes were synthesized via a hydrothermal route. The phase, morphology, and emission spectrum were confirmed for these REMPs by power X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectrophotometry, respectively. A commercial CCD camera equipped with a series of optical filters was employed to quantify the intensity and spectrum of CLI from radionuclides. The enhancement of penetration was investigated by imaging studies of nylon phantoms and nude mouse pseudotumor models. Results: the REMPs could be dually excited by CL at the wavelengths of 520 and 980 nm, and the emission peaks overlaid at 660 nm. This strategy approximately doubled the overall detectable intensity of CLI and extended its maximum penetration in nylon phantoms from 5 to 15 mm. The penetration study in living animals yielded similar results. Conclusions: this study demonstrated that CL can dually excite REMPs and that the overlaid emissions in the range of 660 nm could significantly enhance the penetration and intensity of CL. The proposed enhanced CLI strategy may have promising applications in the future. PMID:24205030

Xu, Feng; Feng, Ailing; Zhao, Ying; Lu, Tianjian; Yang, Weidong; Wang, Zhe; Lin, Min; Wang, Jing

2013-01-01

253

CVT/GPL phase 2 integrated testing. [in earth observations, space physics, and material sciences  

NASA Technical Reports Server (NTRS)

Experiments representing earth observations, space physics, and material sciences disciplines were installed in the General Purpose Laboratory (GPL). The experiments and the GPL are described. The experiments interfaces the GPL and GPL support systems are assessed. The experiments were cloud physics, ionospheric disturbances, material sciences, high energy astronomy, and superfluid helium.

Shurney, R. E.; Maybee, G.; Schmitt, S.

1974-01-01

254

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.

255

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

Microsoft Academic Search

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

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

2005-01-01

256

Integrated hydrological modelling of a managed coastal Mediterranean wetland (Rhone delta, France) Hydrology and Earth System Sciences, 7(1), 123131 (2003) EGU  

E-print Network

Integrated hydrological modelling of a managed coastal Mediterranean wetland (Rhone delta, France) 123 Hydrology and Earth System Sciences, 7(1), 123­131 (2003) © EGU Integrated hydrological modelling. This hydrosystem is subject to strong natural hydrological variability due to the combination of a Mediterranean

Paris-Sud XI, Université de

257

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

258

Er-doped light emitting slot waveguides monolithically integrated in a silicon photonic chip  

NASA Astrophysics Data System (ADS)

An integrated erbium-based light emitting diode has been realized in a waveguide configuration allowing 1.54 ?m light signal routing in silicon photonic circuits. This injection device is based on an asymmetric horizontal slot waveguide where the active slot material is Er3+ in SiO2 or Er3+ in Si-rich oxide. The active horizontal slot waveguide allows optical confinement, guiding and lateral extraction of the light for on-chip distribution. Light is then coupled through a taper section to a passive Si waveguide terminated by a grating which extracts (or inserts) the light signal for measuring purposes. We measured an optical power density in the range of tens of ?W/cm2 which follows a super-linear dependence on injected current density. When the device is biased at high current density, upon a voltage pulse (pump signal), free-carrier and space charge absorption losses become large, attenuating a probe signal by more than 60 dB/cm and thus behaving conceptually as an electro-optical modulator. The integrated device reported here is the first example, still to be optimized, of a fundamental block to realize an integrated silicon photonic circuit with monolithic integration of the light emitter.

Ramírez, J. M.; Ferrarese Lupi, F.; Berencén, Y.; Anopchenko, A.; Colonna, J. P.; Jambois, O.; Fedeli, J. M.; Pavesi, L.; Prtljaga, N.; Rivallin, P.; Tengattini, A.; Navarro-Urrios, D.; Garrido, B.

2013-03-01

259

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

260

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

261

Integrating Public Health, Earth Observation Sciences, and Engineering Information Systems for Critical Disaster Reduction  

Microsoft Academic Search

Disaster epidemiology uses a variety of methods to identify risk factors that predispose individuals or populations to death, injury, or illness during the pre-impact, impact, and post- impact phases of a disaster. Emerging technologies including earth observation sciences (i.e., remote sensing imagery, satellite observations) and engineering information systems (e.g., geographic information systems, database management systems, computing and processing technologies) can

Stacy Young; Josephine Malilay; Carlos Sanchez; Dahna Batts-Osborne

262

Integration of multi-discipline data processing for earth observing systems  

NASA Technical Reports Server (NTRS)

The first steps taken to ensure the controlled evolution of existing facilities toward greater interoperability and sharing of resources among NASA-supported earth science and applications data systems (ESADS) are described. Recommendations made by the various panels during the 1987 ESADS Workshop are presented. The panels were concerned with directories and catalogs, data archives, data manipulation software, computational facilities, data storage media, database management, and networking. Consideration was also given to the tracking and tuning of overall development and management coordination issues.

Kahn, Ralph; Chase, Robert

1987-01-01

263

Integrated Earth Science Research in Deep Underground Science and Engineering Laboratories  

Microsoft Academic Search

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

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

2004-01-01

264

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

265

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

266

Earth Systems Science Earth Systems Science at UNH  

E-print Network

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

Pringle, James "Jamie"

267

Integrating EarthScope Data Into Interactive Visualizations, Movies and High-Resolution Static Images  

NASA Astrophysics Data System (ADS)

What is EarthScope? The answer to this question can best be addressed through images, movies and interactive visualizations. Using these types of visual tools the temporal evolution and spatial scales of the various EarthScope data (e.g., earthquakes, sediment thickness, aquifers, focal mechanisms, topography, moho depth, mines, geology, magnetics, faults and gravity) can be more easily understood. Working with EarthScope researchers we have developed visualizations to assist with data quality (i.e., from SAFOD, USArray and PBO), hypothesis testing and the presentation of final results. Through this process we have identified 6 key areas of interest: (1) Depicting temporal evolution of data; (2) The ability to toggle on/off and color-code data sub-sets for complex high-density data; (3) Developing end-products that can be used as on-line supplements to journal articles; (4) Creating multi-use end-products that benefit researchers, emergency response personnel and education programs; (5) Quality assessing and geo-referencing newly collected data; and (6) Making difficult subjects more understandable. The visualizations we create can be accessed from our website (we get ~4,000 unique visitors to our pages each month) through the visual objects library at the Scripps Institution of Oceanography's Visualization Center (http://siovizcenter.ucsd.edu/library.php). These include 3D interactive visualizations, Quicktime movies and online tools and can be explored using freeware that runs on multiple platforms (e.g., Windows, Mac OS X, Linux, SGI Irix).

Kilb, D.

2008-12-01

268

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

SciTech Connect

Human influence on the hydrologic cycle includes regulation and storage, consumptive use and overall redistribution of water resources in space and time. Representing these processes is essential for applications of earth system models in hydrologic and climate predictions, as well as impact studies at regional to global scales. Emerging large-scale research reservoir models use generic operating rules that are flexible for coupling with earth system models. Those generic operating rules have been successful in reproducing the overall regulated flow at large basin scales. This study investigates the uncertainties of the reservoir models from different implementations of the generic operating rules using the complex multi-objective Columbia River Regulation System in northwestern United States as an example to understand their effects on not only regulated flow but also reservoir storage and fraction of the demand that is met. Numerical experiments are designed to test new generic operating rules that combine storage and releases targets for multi-purpose reservoirs and to compare the use of reservoir usage priorities, withdrawals vs. consumptive demand, as well as natural vs. regulated mean flow for calibrating operating rules. Overall the best performing implementation is the use of the combined priorities (flood control storage targets and irrigation release targets) operating rules calibrated with mean annual natural flow and mean monthly withdrawals. The challenge of not accounting for groundwater withdrawals, or on the contrary, assuming that all remaining demand is met through groundwater extractions, is discussed.

Voisin, Nathalie; Li, Hongyi; Ward, Duane L.; Huang, Maoyi; Wigmosta, Mark S.; Leung, Lai-Yung R.

2013-09-30

269

Integration of Micro-Electro-Mechanical Deformable Mirrors in Doped Fiber Amplifiers  

E-print Network

We present a simple technique to produce active Q-switching in various types of fiber amplifiers by active integration of an electrostatic actuated deformable metallic micro-mirror. The optical MEMS (MOEMS) device acts as one of the laser cavity reflectors and, at the same time, as switching/ modulator element. We aim to obtain laser systems emitting short, high-power pulses and having variable repetition rate. The electro-mechanical behavior of membrane (bridge-type) was simulated by using electrostatic and modal 3D finite element analysis (FEA). The results of the simulations fit well with the experimental mechanical, electrical and thermal measurements of the components. In order to decrease the sensitiveness to fiber-mirror alignment we are developing novel optical devices based on stressed-metal cantilever-type geometry that allow deflections up to 50 $\\mu$m with increased reflectivity discrimination during actuation.

Bouyge, D; Crunteanu, A; Blondy, P; Couderc, V; Lhermite, J; Grossard, L; Barthélemy, A

2007-01-01

270

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

Microsoft Academic Search

Systems thinking is regarded as a high-order thinking skill required in scientific, technological, and everyday domains. However, little is known about systems thinking in the context of science education. In the current research, students' understanding of the rock cycle system after a learning program was characterized, and the effect of a concluding knowledge integration activity on their systems thinking was

Yael Kali; Nir Orion; Bat-Sheva Eylon

2003-01-01

271

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

NASA Astrophysics Data System (ADS)

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

Pinkham, Raymond; Anderson, Daniel F.

1986-08-01

272

Path Integral Monte Carlo Study Confirms a Highly Ordered Snowball in 4He Nanodroplets Doped with an Ar+ Ion  

NASA Astrophysics Data System (ADS)

By means of the exact Path Integral Monte Carlo method we have performed a detailed microscopic study of $^4$He 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; the dissociation energy curve computed in the present work shows jumps in correspondence with those found in the nanodroplets abundance distribution measured in that experiment, strengthening the agreement between theory and experiment. The same structures were predicted in Ref. [Galli et al, J. Phys. Chem. A 115, 2011] in a study regarding Na$^+$@$^4$He$_n$ when n>30; a comparison between Ar$^+$@$^4$He$_n$ and Na$^+$@$^4$He$_n$ complexes is also presented.

Tramonto, F.; Salvestrini, P.; Nava, M.; Galli, D. E.

2015-01-01

273

Integrated propulsion for near-Earth space missions. Volume 2: Technical  

NASA Technical Reports Server (NTRS)

The calculation approach is described for parametric analysis of candidate electric propulsion systems employed in LEO to GEO missions. Occultation relations, atmospheric density effects, and natural radiation effects are presented. A solar cell cover glass tradeoff is performed to determine optimum glass thickness. Solar array and spacecraft pointing strategies are described for low altitude flight and for optimum array illumination during ascent. Mass ratio tradeoffs versus transfer time provide direction for thruster technology improvements. Integrated electric propulsion analysis is performed for orbit boosting, inclination change, attitude control, stationkeeping, repositioning, and disposal functions as well as power sharing with payload on orbit. Comparison with chemical auxiliary propulsion is made to quantify the advantages of integrated propulsion in terms of weight savings and concomittant launch cost savings.

Dailey, C. L.; Meissinger, H. F.; Lovberg, R. H.; Zafran, S.

1981-01-01

274

DILIGENT: integrating digital library and Grid technologies for a new Earth observation research infrastructure  

Microsoft Academic Search

This paper introduces DILIGENT, a digital library infrastructure built by integrating digital library and Grid technologies and resources. This infrastructure\\u000a allows different communities to dynamically build specialised digital libraries capable to support the entire e-Science knowledge\\u000a production and consumption life-cycle by using shared computing, storage, content, and application resources. The paper presents\\u000a some of the main software services that implement

Leonardo Candela; Fuat Akal; Henri Avancini; Donatella Castelli; Luigi Fusco; Veronica Guidetti; Christoph Langguth; Andrea Manzi; Pasquale Pagano; Heiko Schuldt; Manuele Simi; Michael Springmann; Laura Voicu

2007-01-01

275

Combining sky and earth: desert ants (Melophorus bagoti) show weighted integration of celestial and terrestrial cues.  

PubMed

Insects typically use celestial sources of directional information for path integration, and terrestrial panoramic information for view-based navigation. Here we set celestial and terrestrial sources of directional information in conflict for homing desert ants (Melophorus bagoti). In the first experiment, ants learned to navigate out of a round experimental arena with a distinctive artificial panorama. On crucial tests, we rotated the arena to create a conflict between the artificial panorama and celestial information. In a second experiment, ants at a feeder in their natural visually-cluttered habitat were displaced prior to their homing journey so that the dictates of path integration (feeder to nest direction) based on a celestial compass conflicted with the dictates of view-based navigation (release point to nest direction) based on the natural terrestrial panorama. In both experiments, ants generally headed in a direction intermediate to the dictates of celestial and terrestrial information. In the second experiment, the ants put more weight on the terrestrial cues when they provided better directional information. We conclude that desert ants weight and integrate the dictates of celestial and terrestrial information in determining their initial heading, even when the two directional cues are highly discrepant. PMID:25324340

Legge, Eric L G; Wystrach, Antoine; Spetch, Marcia L; Cheng, Ken

2014-12-01

276

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.

277

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

278

Synchrotron X-Ray Topography Study of Structural Defects and Strain in Epitaxial Structures of Yb- and Tm-Doped Potassium Rare-Earth Double Tungstates and Their Influence on Laser Performance  

NASA Astrophysics Data System (ADS)

Monoclinic potassium rare-earth double tungstates [KRE(WO4)2, RE = Y, Lu, Yb; KREW] are well suited as hosts for active lanthanide ion (Ln3+) dopants for diode-pumped solid-state lasers, with particular interest in thin-disk laser configurations when they are grown as thin films. Using synchrotron white-beam x-ray topography, we have imaged defects and strain in top-seeded solution-grown (TSSG) bulk substrates of different rare-earth tungstates as well as within Yb3+- and Tm3+-doped epitaxies for thin-disk laser applications grown on these substrates by liquid-phase epitaxy. Higher structural stress in Yb:KYW/KYW epitaxies compared with Yb:KLuW/KLuW epitaxies is found to lower efficiency in laser operation. The quality of Tm:KLuW/KLuW epitaxial films is sensitive to doping level, film thickness, and growth rate. Inhomogeneous stresses within the layers are dominated by lattice-mismatch effects rather than by crystallographic anisotropy.

Raghothamachar, B.; Carvajal, J. J.; Pujol, M. C.; Mateos, X.; Solé, R.; Aguiló, M.; Díaz, F.; Dudley, M.

2010-06-01

279

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...

280

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

281

Earth tides  

SciTech Connect

Nineteen papers on gravity, tilt, and strain tides are compiled into this volume. Detailed chapters cover the calculation of the tidal forces and of the Earth's response to them, as well as actual observations of earth tides. Partial Contents: On Earth tides. The tidal forces: Tidal Forces. New Computations of the Tide-Generating Potential. Corrected Tables of Tidal Harmonics. The Theory of Tidal Deformations. Body Tides on an Elliptical, Rotating, Elastic and Oceanless Earth, Deformation of the Earth by Surface Loads. Gravimetric Tidal Loading Computed from Integrated Green's Functions. Tidal Friction in the Solid Earth. Loading Tides Versus Body Tides. Lunar Tidal Acceleration from Earth Satellite Orbit Analysis. Observations: gravity. Tidal Gravity in Britain: Tidal Loading and the Spatial Distribution of the Marine Tide. Tidal Loading along a Profile Europe-East Africa-South Asia-Australia and the Pacific Ocean. Detailed Gravity-Tide Spectrum between One and Four Cycles per Day. Observations: tilt and strain. Cavity and Topographic Effects in Tilt and Strain Measurement. Observations of Local Elastic Effects on Earth Tide Tilts and Strains.

Harrison, J.C.

1984-01-01

282

MAPS (My Atlas and Plot Service) for Integrated Earth Observation Data  

NASA Astrophysics Data System (ADS)

DIAS (Data integration and Analysis System) is one of the activities of GEOSS, and also one of Japanese National Key Technology activities. JAMSTEC collaborates with the University of Tokyo, the main contractor of the project. It is a five-year project until March 2011. We at JAMSTEC also have developed a data distribution system toward long-term sustainable services as part of DIAS. We launched the early website at 2007. It provided six integration and analysis datasets in the fields of “Ocean & Fishery Resources”, “Water Cycle” and “Land Ecosystem”. We also investigated users’ needs through an online questionnaire and through interviews regarding the types and quality of required data, data formats, website functions and so on. Accordingly, our new website, MAPS, which is short for My Atlas and Plot Service has been remodeled with four new datasets and new functions to meet users’ needs since the fall in 2010. We have provided online mapping and plotting services with MapServer, and download services with functions of extracting digital data by selected attribute and of converting into another file type. These services provide a powerful visualization and analysis capabilities for the data products. The input items and forms in online questionnaire and Contact-Us page in our website have been refined to collect feedbacks and comments about the new website functions. We are continuously researching the further future needs in order to promote the wider usage of the datasets.

Ichino, M.; Fukuda, K.; Sugiura, N.; Funakoshi, R.

2010-12-01

283

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

284

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

285

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

286

carleton.ca Earth Sciences  

E-print Network

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

Dawson, Jeff W.

287

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

288

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

289

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

290

Evaluating and improving hydrologic processes in the community land model for integrated earth system modeling  

NASA Astrophysics Data System (ADS)

High climatic sensitivity and low anthropogenic influence make glacierized river basins important environments for examining hydrological and ecological response to global change. This paper synthesises findings from previous and ongoing research in glacierized Alpine and Arctic river basins (located in the French Pyrenees, New Zealand, Swedish Lapland and Svalbard), which adopts an interdisciplinary approach to investigate the climate-cryosphere-hydrology-ecology cascade. Data are used to advance hypotheses concerning the consequences of climate change/ variability on glacier river system hydrology and ecology. Aquatic ecosystems in high latitude and altitude environments are influenced strongly by cryospheric and hydrological processes due to links between atmospheric forcing, snowpack/ glacier mass-balance, river runoff, physico-chemistry and biota. In the current phase of global warming, many glaciers are retreating. Using downscaled regional climate projections as inputs to a distributed hydrological model for a study basin in the French Pyrenees (i.e. an environment at the contemporary limit of valley glaciation), we show how shrinking snow and ice-masses may alter space-time dynamics in basin runoff. Notably, the timing of peak snow- and ice-melt may shift; and the proportion of stream flow sourced from rainfall-runoff (cf. meltwater) may increase. Across our range of Alpine and Arctic study basins, we quantify observed links between relative water source contributions (% meltwater : % groundwater), physico-chemical habitat (e.g. water temperature, electrical conductivity, suspended sediment and channel stability) and benthic communities. At the site scale, results point towards increased community diversity (taxonomic and functional) as meltwater contributions decline and physico-chemical habitat becomes less harsh. However, basin-scale biodiversity may be reduced due to less spatio-temporal heterogeneity in water source contributions and habitats, and the extinction of cold stenothermic specialists. Similar integrated, long-term research into hydroecological connections in other glacierized river basins is vital: (1) to enable robust projections of stream hydrology (water source contributions and physico-chemical habitat) and ecological response under scenarios of future climate/ variability, and (2) to develop conservation strategies for these fragile Alpine and Arctic freshwater ecosystems.

Hannah, D. M.; Khamis, K.; Blaen, P. J.; Hainie, S.; Mellor, C.; Brown, L. E.; Milner, A. M.

2011-12-01

291

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

292

Photoinduced phenomena in chalcogenide glasses doped with metals  

E-print Network

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

Boolchand, Punit

293

Rare Earth Ion Effects on the Pseudo-Gap in Electron-Doped Superconductors And Possible Nodeless D-Wave Gap  

SciTech Connect

We report angle resolved photoemission (ARPES) studies on electron-doped cuprate superconductor Sm{sub 2-x}Ce{sub x}CuO{sub 4} (x = 0.14 and 0.18). A wide energy range scan shows clear 'waterfall' effect at an energy scale close to 500 meV which is consistent with the value found in Nd{sub 2-x}Ce{sub x}CuO{sub 4} (NCCO) but larger than that from hole-doped superconductors. High resolution results from both dopings show pseudo-gap effects that were observed in NCCO. However, the effects are found to be stronger than that observed in optimally doped NCCO. The overall electronic structure is well understood within a simple model in which a {radical}2 x {radical}2 static order is assumed. Both ARPES and optical measurements give the coupling strengths to the Q = ({pi}/2,{pi}/2) (due to the {radical}2 x {radical}2 order) to be about 0.1 eV, compatible with each other. The effect is strong enough to push the band near the nodal region below the Fermi energy, resulting in possible nodeless d-wave superconductivity where zero energy quasi-particle excitation is inhibited.

Park, S.R.; Leem, C.S.; Roh, Y.S.; Choi, K.J.; Kim, J.H.; Kim, B.J.; Koh, H.; Eisaki, H.; Lu, D.H.; Shen, Z.-X.; Armitage, N.P.; Kim, C.

2009-05-21

294

Luminescent properties of rare-earth-metal ion-doped KLaNb{sub 2}O{sub 7} with layered perovskite structures  

SciTech Connect

The photochemical properties of layered materials has been extensively studied, but the photochemical properties of two-dimensional oxides of layered compounds has not. This study examined the photoluminescence and thermoluminescence of lanthanide-metal-ion-doped KLaNb{sub 2}O{sub 7} with a layered perovskite structure. 16 refs., 5 figs.

Kudo, Akihiko [Science Univ. of Tokyo (Japan)] [Science Univ. of Tokyo (Japan)

1997-03-01

295

EPOS the European Plate Observing System: a long-term integration plan for research infrastructures on solid Earth sciences at pan-European level  

NASA Astrophysics Data System (ADS)

EPOS (European Plate Observing System) aims to integrate data from permanent national and regional geophysical monitoring networks (seismological, GPS), with the observations from "in-situ" observatories (volcano observatories, in-situ fault zone test sites, etc....) and temporary-monitoring and laboratory experiments through a cyber-infrastructure for data mining and processing, and facilities for data integration, archiving and exchange. By providing an unprecedented high-quality multidisciplinary service to users, EPOS will foster and support research on earthquakes, volcanoes, surface dynamics and tectonics, and will complement similar initiatives in satellite Earth observing systems and ocean sciences. EPOS main aim is to create a coherent Research Infrastructure enabling the next generation of scientists to pursue innovative and challenging solid Earth science research in Europe and in the Mediterranean regions. EPOS has been included in the European roadmap for research infrastructures after positive evaluation by ESFRI (European Strategy Forum on Research Infrastructures) in December 2008. A preparatory phase proposal has been recently submitted to the last EC Call in the Capacities Work Program. Here we present the EPOS concept and the strategic plans for its preparatory phase, focusing on the implementation plan and vision to create an effective service to users. Making observations of solid Earth dynamic processes controlling natural phenomena immediately available and promoting their comparison with experimental observations from cutting-edge laboratory experiments and their interpretation through theoretical analyses and numerical simulations will represent a multidisciplinary platform for discoveries which will foster scientific excellence in solid Earth research.

Cocco, Massimo; van Eclk, Torild; Michelini, Alberto; Epos Team

2010-05-01

296

Effects of atmospheric dynamics and ocean resolution on bi-stability of the thermohaline circulation examined using the Grid ENabled Integrated Earth system modelling (GENIE) framework  

Microsoft Academic Search

We have used the Grid ENabled Integrated Earth system modelling (GENIE) framework to undertake a systematic search for bi-stability\\u000a of the ocean thermohaline circulation (THC) for different surface grids and resolutions of 3-D ocean (GOLDSTEIN) under a 3-D\\u000a dynamical atmosphere model (IGCM). A total of 407,000 years were simulated over a three month period using Grid computing.\\u000a We find bi-stability of

T. M. Lenton; R. Marsh; A. R. Price; D. J. Lunt; Y. Aksenov; J. D. Annan; T. Cooper-Chadwick; S. J. Cox; N. R. Edwards; S. Goswami; J. C. Hargreaves; P. P. Harris; Z. Jiao; V. N. Livina; A. J. Payne; I. C. Rutt; J. G. Shepherd; P. J. Valdes; G. Williams; M. S. Williamson; A. Yool

2007-01-01

297

The Use of the Integrated Medical Model for Forecasting and Mitigating Medical Risks for a Near-Earth Asteroid Mission  

NASA Technical Reports Server (NTRS)

Introduction The Integrated Medical Model (IMM) is a decision support tool that is useful to space flight mission managers and medical system designers in assessing risks and optimizing medical systems. The IMM employs an evidence-based, probabilistic risk assessment (PRA) approach within the operational constraints of space flight. Methods Stochastic computational methods are used to forecast probability distributions of medical events, crew health metrics, medical resource utilization, and probability estimates of medical evacuation and loss of crew life. The IMM can also optimize medical kits within the constraints of mass and volume for specified missions. The IMM was used to forecast medical evacuation and loss of crew life probabilities, as well as crew health metrics for a near-earth asteroid (NEA) mission. An optimized medical kit for this mission was proposed based on the IMM simulation. Discussion The IMM can provide information to the space program regarding medical risks, including crew medical impairment, medical evacuation and loss of crew life. This information is valuable to mission managers and the space medicine community in assessing risk and developing mitigation strategies. Exploration missions such as NEA missions will have significant mass and volume constraints applied to the medical system. Appropriate allocation of medical resources will be critical to mission success. The IMM capability of optimizing medical systems based on specific crew and mission profiles will be advantageous to medical system designers. Conclusion The IMM is a decision support tool that can provide estimates of the impact of medical events on human space flight missions, such as crew impairment, evacuation, and loss of crew life. It can be used to support the development of mitigation strategies and to propose optimized medical systems for specified space flight missions. Learning Objectives The audience will learn how an evidence-based decision support tool can be used to help assess risk, develop mitigation strategies, and optimize medical systems for exploration space flight missions.

Kerstman, Eric; Saile, Lynn; Freire de Carvalho, Mary; Myers, Jerry; Walton, Marlei; Butler, Douglas; Lopez, Vilma

2011-01-01

298

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

299

Rare-earth-ion-doped ultra-narrow-linewidth lasers on a silicon chip and applications to intra-laser-cavity optical sensing  

NASA Astrophysics Data System (ADS)

We report on diode-pumped distributed-feedback (DFB) and distributed-Bragg-reflector (DBR) channel waveguide lasers in Er-doped and Yb-doped Al2O3 on standard thermally oxidized silicon substrates. Uniform surface-relief Bragg gratings were patterned by laser-interference lithography and etched into the SiO2 top cladding. The maximum grating reflectivity exceeded 99%. Monolithic DFB and DBR cavities with Q-factors of up to 1.35×106 were realized. The Erdoped DFB laser delivered 3 mW of output power with a slope efficiency of 41% versus absorbed pump power. Singlelongitudinal- mode operation at a wavelength of 1545.2 nm was achieved with an emission line width of 1.70 0.58 kHz, corresponding to a laser Q-factor of 1.14×1011. Yb-doped DFB and DBR lasers were demonstrated at wavelengths near 1020 nm with output powers of 55 mW and a slope efficiency of 67% versus launched pump power. An Yb-doped dualwavelength laser was achieved based on the optical resonances induced by two local phase shifts in the DFB structure. A stable microwave signal at ~15 GHz with a -3-dB width of 9 kHz and a long-term frequency stability of +/- 2.5 MHz was created via the heterodyne photo-detection of the two laser wavelengths. By measuring changes in the microwave beat signal as the intra-cavity evanescent laser field interacts with micro-particles on the waveguide surface, we achieved real-time detection and accurate size measurement of single micro-particles with diameters ranging between 1 ?m and 20 ?m, which represents the typical size of many fungal and bacterial pathogens. A limit of detection of ~500 nm was deduced.

Bernhardi, E. H.; de Ridder, R. M.; Wörhoff, K.; Pollnau, M.

2013-03-01

300

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

PubMed

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

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

2015-01-14

301

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

302

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

303

The effect of doping rare-earth chloride dopant on the dehydrogenation properties of NaAlH 4 and its catalytic mechanism  

Microsoft Academic Search

A series of rare-earth chlorides has been adopted to catalyze dehydrogenation reaction of NaAlH4. X-ray diffraction analysis and isothermal dehydrogenation measurement have proved that these chlorides enhance the dehydrogenation kinetics and lower the decomposition temperature of NaAlH4. The catalytic effect from high to low is in following order: SmCl3>CeCl3>TiCl3>NdCl3>GdCl3>LaCl3>ErCl3. In order to reveal the catalytic mechanism of the rare-earth chlorides

T. Sun; B. Zhou; H. Wang; M. Zhu

2008-01-01

304

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

305

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

306

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

307

EarthLabs: Teacher's Guide  

NSDL National Science Digital Library

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

308

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.

309

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

310

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

311

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

312

Integrating land management into Earth system models: the importance of land use transitions at sub-grid-scale  

NASA Astrophysics Data System (ADS)

Recent studies indicate that changes in surface climate and carbon fluxes caused by land management (i.e., modifications of vegetation structure without changing the type of land cover) can be as large as those caused by land cover change. Further, such effects may occur on substantial areas: while about one quarter of the land surface has undergone land cover change, another fifty percent are managed. This calls for integration of management processes in Earth system models (ESMs). This integration increases the importance of awareness and agreement on how to diagnose effects of land use in ESMs to avoid additional model spread and thus unnecessary uncertainties in carbon budget estimates. Process understanding of management effects, their model implementation, as well as data availability on management type and extent pose challenges. In this respect, a significant step forward has been done in the framework of the current IPCC's CMIP5 simulations (Coupled Model Intercomparison Project Phase 5): The climate simulations were driven with the same harmonized land use dataset that, different from most datasets commonly used before, included information on two important types of management: wood harvest and shifting cultivation. However, these new aspects were employed by only part of the CMIP5 models, while most models continued to use the associated land cover maps. Here, we explore the consequences for the carbon cycle of including subgrid-scale land transformations ("gross transitions"), such as shifting cultivation, as example of the current state of implementation of land management in ESMs. Accounting for gross transitions is expected to increase land use emissions because it represents simultaneous clearing and regrowth of natural vegetation in different parts of the grid cell, reducing standing carbon stocks. This process cannot be captured by prescribing land cover maps ("net transitions"). Using the MPI-ESM we find that ignoring gross transitions underestimates emissions substantially, for historical times by about 40%. Implementation of land management such as gross transitions is a step forward in terms of comprehensiveness of simulated processes. However, it has increased model spread in carbon fluxes, because land management processes have been considered by only a subset of recent ESMs contributing to major projects such as IPCC or the Global Carbon Project. This model spread still causes the net land use flux to be the most uncertain component in the global carbon budget. Other causes have previously been identified as differences in land use datasets, differing types of vegetation model, accounting of nutrient limitation, the inclusion of land use feedbacks (increase in atmospheric CO2 due to land use emissions causing terrestrial carbon uptake), and a confusion of whether the net land use flux in ESMs should be reported as instantaneous emissions, or also account for delayed carbon responses and regrowth. These differences explain a factor 2-6 difference between model estimates and are expected to be further affected by interactions with land management. This highlights the importance of an accurate protocol for future model intercomparisons of carbon fluxes from land cover change and land management to ensure comparison of the same processes and fluxes.

Pongratz, Julia; Wilkenskjeld, Stiig; Kloster, Silvia; Reick, Christian

2014-05-01

313

Defect Clustering and Nano-phase Structure Characterization of Multicomponent Rare Earth-Oxide-Doped Zirconia-Yttria Thermal Barrier Coatings  

NASA Technical Reports Server (NTRS)

Advanced thermal barrier coatings (TBCs) have been developed by incorporating multicomponent rare earth oxide dopants into zirconia-based thermal barrier coatings to promote the creation of the thermodynamically stable, immobile oxide defect clusters and/or nanophases within the coating systems. In this paper, the defect clusters, induced by Nd, Gd, and Yb rare earth dopants in the zirconia-yttria thermal barrier coatings, were characterized by high-resolution transmission electron microscopy (TEM). The TEM lattice imaging, selected area diffraction (SAD), and electron energy-loss spectroscopy (EELS) analyses demonstrated that the extensive nanoscale rare earth dopant segregation exists in the plasma-sprayed and electron-physical-vapor-deposited (EB PVD) thermal barrier coatings. The nanoscale concentration heterogeneity and the resulting large lattice distortion promoted the formation of parallel and rotational defective lattice clusters in the coating systems. The presence of the 5-to 100-nm-sized defect clusters and nanophases is believed to be responsible for the significant reduction of thermal conductivity, improved sintering resistance, and long-term high temperature stability of the advanced thermal barrier coating systems.

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

2004-01-01

314

Energies of 4f^N and 4f^N-15d States Relative to Host Bands in Rare-earth-doped Fluorides  

NASA Astrophysics Data System (ADS)

Energies of 4f^N states relative to crystal band states were measured for rare-earth ions in the optical host materials LiYF4, Na0.4Y0.6F2.2, and LaF3 using x-ray photoemission spectroscopy. Spectra were modeled to determine the valence band maximum and 4f^ electron binding energies in each material. These results were combined with 4f^N to 4f^N-15d transition energies to determine 5d binding energies for the lowest levels of excited 4f^N-15d configurations. While 4f^N ground-state energies vary within several eV of the valence band maximum for different rare-earth ions in each host, the lowest 4f^N-15d states have similar energies and are several eV below the bottom of the conduction band. A simple model accurately described 4f^N and 4f^N-15d binding energies across the entire series of rare-earth ions. These results improve the understanding of optical materials for lasers, phosphors, and spectral hole burning applications for optical signal processing and data storage.

Thiel, C. W.; Joubert, M.-F.; Tkachuk, A.

2005-03-01

315

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.

316

Rare-earth-doped HfO2 nanoparticles embedded in SiO2-HfO2 planar waveguides: preparation and optical, structural, and spectroscopic characterization  

NASA Astrophysics Data System (ADS)

In this work we present result on the preparation of planar waveguides based on HfO2 and HfO2-SiO$2). Stable sols containing europium and erbium doped HfO2 nanoparticles have been prepared and characterized. The nanosized sol was either deposited on quartz substrates or embedded in (3-glycidoxipropil)trimethoxisilane used as a hybrid host for posterior deposition. The refractive index dispersion and luminescence characteristics were determined for the resulting HfO2 films. The optical parameters of the waveguides such as refractive index, thickness and propagation losses were measured for the hybrid composite. The planar waveguides present thickness of a few micra and support well confined propagating modes.

Ribeiro, Sidney J. L.; Goncalves, Rogeria R.; Messaddeq, Younes; Aegerter, Michel A.; Montagna, Maurizio; Duverger, Claire; Ferrari, Maurizio

2000-05-01

317

Effects of PbF2 doping on structure and spectroscopic properties of Ga2O3-GeO2-Bi2O3-PbO glasses doped with rare earths  

NASA Astrophysics Data System (ADS)

We report an intense room-temperature blue upconversion in Tm3+/Yb+3-codoped Ga2O3-GeO2-Bi2O3-PbO(PbF2) glasses upon excitation with a convenient 980 nm laser diode. Effects of PbF2 doping on the thermal stability, structure, and upconversion properties of Tm3+/Yb3+-codoped gallate-germanium-bismuth-lead glasses have been investigated. We find that the presence of PbF2 provides two potentials: shortening the ultraviolet cutoff band and decreasing the phonon energy of host glasses. The blue-upconversion intensity has a cubelike dependence on incident pump-laser power, indicating a three-photon process. Energy-transfer process and nonradiative phonon-assisted decay could be responsible for the population of the 1G4 emitting level of the Tm3+. The results indicate the potential possibility towards the development of an oxide-based blue-upconversion glass-fiber laser.

Zhang, Q. Y.; Li, T.; Shi, D. M.; Yang, G. F.; Yang, Z. M.; Jiang, Z. H.; Buddhudu, S.

2006-02-01

318

Practicing ESD at School: Integration of Formal and Nonformal Education Methods Based on the Earth Charter (Belarusian Experience)  

ERIC Educational Resources Information Center

The Earth Charter represents the philosophy and ethics necessary to create a new period of human civilization. Understanding and adoption of this new vision is the most important mission of education for sustainable development (ESD). This article argues that for successful implementation of ESD principles at school, the school education system…

Savelava, Sofia; Savelau, Dmitry; Cary, Marina Bakhnova

2010-01-01

319

Superconductivity in rare-earth-doped oxygen-defect perovskites La 2-x-yLn ySr xCuO 4-z  

NASA Astrophysics Data System (ADS)

The structural, magnetic, and electronic properties of the mixed compounds La 2-x-yLn ySr xCuO 4 for 0.15earths are present in these materials as trivalent ions. DC resistance, ac susceptibility, Meissner and shielding measurements have shown that superconductivity persists among several members of the series. The magnetic rare earth ions depress T c but do not destroy superconductivity. Within the series x=0.2 and y=0.3, the superconductivity transition temperatures, taken at the midpoint in resistivity, decrease from a maximum value at La (36.8K) to a minimum value at Gd (18.5K). It is suggested that the unit cell volume contraction observed through the lanthanide sequence, rather than magnetic interactions, is responsible for the observed depression in T c.

Tarascon, J. M.; Greene, L. H.; McKinnon, W. R.; Hull, G. W.

1987-08-01

320

Earth Institute  

NSDL National Science Digital Library

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

321

Oxygen vacancy ordering in strontium doped rare earth cobaltate perovskites Ln{sub 1-x}Sr {sub x}CoO{sub 3-{delta}} (Ln = La, Pr and Nd; x > 0.60)  

SciTech Connect

A family of Sr-doped perovskite compounds Ln{sub 1-x}Sr {sub x}CoO{sub 3-{delta}} (Ln = La{sup 3+}, Pr{sup 3+} and Nd{sup 3+}; x > 0.60), were prepared by sol-gel chemistry and reaction at 1100 deg. C under 1 atm of oxygen. This structural family has been shown to be present only for rare earth ions larger than Sm{sup 3+} and an upper limit of Sr{sup 2+} solubility in these phases was found to exist between x = 0.90 and 0.95. X-ray diffraction shows oxygen-deficient, simple cubic (Pm-3m) perovskite crystal structures. The combination of electron and powder neutron diffraction reveals that oxygen vacancy ordering occurs, leading to a tetragonal (P4/mmm) superstructure and a doubling of the basic perovskite unit along the crystallographic c-axis. No additional Ln{sup 3+}/Sr{sup 2+} cation ordering was observed.

James, M. [Bragg Institute, Australian Nuclear Science and Technology Organisation, Building 58, ANSTO, PMB 1, Menai NSW 2234 (Australia)]. E-mail: mja@ansto.gov.au; Tedesco, T. [Bragg Institute, Australian Nuclear Science and Technology Organisation, Building 58, ANSTO, PMB 1, Menai NSW 2234 (Australia); Cassidy, D.J. [Materials and Engineering Sciences, Australian Nuclear Science and Technology Organisation, PMB 1, Menai NSW 2234 (Australia); Withers, R.L. [Research School of Chemistry, Australian National University, Canberra, ACT 0200 (Australia)

2005-06-15

322

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

323

Earth Science Week  

NSDL National Science Digital Library

Each year, Earth Science Week focuses on a different facet of earth science to help people gain a better understanding and appreciation of the natural world. This website contains information about ways for classrooms to integrate Earth Science Week into their curriculum each year. This includes ways to involve the community, contests, and grade-level appropriate activities surrounding the year's theme. The site also includes a list of links to educational resources related to the current theme.

324

Mapping of integrated radon emanation for detection of long-distance migration of gases within the earth: Techniques and principles  

Microsoft Academic Search

Integrated measurements of radon concentrations within the ground but close to the surface are being used extensively in search for premonitory signals from earthquakes and in exploration for uranium. We present a description of the different components of the radon signals that may be present and describe methods for separating them. We also show quantitatively what signals the different radon-integrating

Robert L. Fleischer; Antonio Mogro-Campero

1978-01-01

325

Synthesis and characterization of visible emission from rare-earth doped aluminum nitride, gallium nitride and gallium aluminum nitride powders and thin films  

NASA Astrophysics Data System (ADS)

A three-step solution-based process had been used synthesize powders of GaN, AlN and their alloys. The complete solid solubility and tunable nature of these nitride band gaps in the visible spectrum were the motivation of these studies due to their application in solid state lighting. Energy dispersive X-ray spectroscopy confirmed the reduction in oxygen content for the GaN powders to as low as 4 atom % with an 8 % oxygen to nitrogen ratio. Relative to commercial GaN powders, the bandedge of the powders synthesized by such approach also shifted to higher energy, which indicated fewer defects, as observed from reflectance measurements. Inspired by the use of rare-earth elements as color emitters in fluorescent lamp phosphors, these elements were also used as activators in our nitride material. Visible emission was demonstrated through photoluminescence measurements in AlN powders activated with rare-earth elements Eu3+, Tb3+, Tm3+. These ions showed emission in the red, green and blue regions of the visible spectrum, respectively. Eu3+ and Tb3+ co-activation was also observed in an AlN sample that indicated successful energy transfer from the host to sensitizer, and subsequently to another activator. Tb3+ emission was observed under cathodoluminescence in GaN powders synthesized by the same method, and a concentration study showed no effect of concentration quenching up to 8 atom %. Using the same source powder, a pulsed-laser deposited thin film was fabricated that showed both band gap emission and activator-related emission, suggesting a reduction of defects when the powders were deposited as thin films. Additionally, GaN:Tb3+ films were also fabricated using metallorganic vapor phase epitaxy using precursors with and without oxygen ligands. Tb3+ emission was only observed in the sample fabricated from the precursor with oxygen ligand, suggestion that oxygen may be required for effective rare earth luminescence. Finally, Ga1-xAl xN alloy powders (x=0.5) and Ga1-x-yAlxDy yN (x=0.10, 0.30, y=0.01) powders were synthesized using the solution method while incorporating a stainless steel pressure vessel, which increased the synthesis pressure and aided the formation of a single phase hydroxide precursor. This in turn produced a single phase alloy nitride in the final step. Dy3+ emission that was not observed in GaN powders was also observed in the Ga1-x-yAlxDyyN powder. This suggested that the incorporation of aluminum enabled rare-earth emission in the nitrides synthesized for these experiments. However, attempts to sputter nitride alloy thin films via radio frequency sputtering were unsuccessful; only very minor peak shifts in the X-ray diffraction patterns were observed. Nevertheless, energy dispersive X-ray spectroscopy indicates the presence of Al in the Ga0.5Al0.5N film deposited on a Si substrate. This suggested that Al atoms may have segregated from the alloy lattice during the deposition process, with only a small amount of Al atoms incorporated into the GaN lattice.

Tao, Jonathan Huai-Tse

326

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

327

Correlation between rare-earth oscillator strengths and rare-earth-valence-band interactions in neodymium-doped YMO4 (M=V, P, As), Y3Al5O12, and LiYF4 matrices  

NASA Astrophysics Data System (ADS)

Nd3+:YVO4 is one of the more promising laser hosts for micro and diode-pumped solid-state lasers. At room temperature, Nd3+ ions in this matrix exhibit strong absorption cross sections sixfold higher than in Y3Al5O12. The neodymium oscillator strengths are measured in YMO4 (M=V, P, As), Y3Al5O12, and LiYF4 hosts, and they increase in the sequence Y3Al5O12earth occurs via the valence-band levels. This model shows that the oscillator strengths increase with the Nd 4f-valence-band interactions.

Guillot-Noel, O.; Bellamy, B.; Viana, B.; Gourier, D.

1999-07-01

328

Polar Misunderstandings: Earth's Dynamic Dynamo  

ERIC Educational Resources Information Center

This article discusses the movement of Earth's north and south poles. The Earth's poles may be a bit more complex and dynamic than what many students and teachers believe. With better understanding, offer them up as a rich landscape for higher-level critical analysis and subject integration. Possible curriculum tie-ins include magnets, Earth

DiSpezio, Michael A.

2011-01-01

329

Expedition Earth and Beyond: Engaging Classrooms in Student-Led Research Using NASA Data, Access to Scientists, and Integrated Educational Strategies  

NASA Technical Reports Server (NTRS)

Classroom teachers are challenged with engaging and preparing today s students for the future. Activities are driven by state required skills, education standards, and high-stakes testing. Providing educators with standards-aligned, inquiry-based activities that will help them engage their students in student-led research in the classroom will help them teach required standards, essential skills, and help inspire their students to become motivated learners. The Astromaterials Research and Exploration Science (ARES) Education Program, classroom educators, and ARES scientists at the NASA Johnson Space Center created the Expedition Earth and Beyond education program to help teachers promote student-led research in their classrooms (grades 5-14) by using NASA data, providing access to scientists, and using integrated educational strategies.

Graff, P. V.; Stefanov, W. L.; Willis, K. J.; Runco, S.; McCollum, T.; Baker, M.; Lindgren, C.; Mailhot, M.

2011-01-01

330

The need and potential for building a integrated knowledge-base of the Earth-Human system  

NASA Astrophysics Data System (ADS)

The pursuit of scientific understanding is increasingly based on interdisciplinary research. To understand more deeply the planet and its interactions requires a progressively more holistic approach, exploring knowledge coming from all scientific and engineering disciplines including but not limited to, biology, chemistry, computer sciences, geosciences, material sciences, mathematics, physics, cyberinfrastucture, and social sciences. Nowhere is such an approach more critical than in the study of global climate change in which one of the major challenges is the development of next-generation Earth System Models that include coupled and interactive representations of ecosystems, agricultural working lands and forests, urban environments, biogeochemistry, atmospheric chemistry, ocean and atmospheric currents, the water cycle, land ice, and human activities.

Jacobs, Clifford

2011-03-01

331

Ray-tracing studies and path-integrated gains of ELF unducted whistler mode waves in the earth's magnetosphere  

NASA Technical Reports Server (NTRS)

Gyroresonance and Landau resonance interactions between unducted low-frequency whistler waves and trapped electrons in the earth's plasmasphere have been studied. Ray paths for waves launched near the plasmapause have been traced. In agreement with recent findings by Thorne et al. (1979), waves have been found which return through the equatorial zone with field-aligned wave normal angles. However, when the growth along the ray path is calculated for such waves, assuming an electron distribution function of the form E exp -n sin exp m alpha, it is found that for all the waves considered, the local growth rate becomes negative before plasmapause reflection, limiting the total gain to small values. Most waves reach zero gain before reflection. This is the result of Landau damping at oblique propagation angles, which necessarily occurs before reflection can take place. It is concluded that the concept of cyclic ray paths does not provide an explanation for the generation of unguided plasmaspheric hiss.

Huang, C. Y.; Goertz, C. K.

1983-01-01

332

The EarthCARE space-borne Doppler 94 GHz radar simulator: correction of multiple scattering, aliasing and NUBF and effects of variable along track integration  

NASA Astrophysics Data System (ADS)

The primary goal of this work is to address several challenges related to spaceborne Doppler radars like future the EarthCARE mission and recent developments of data simulation, correction and processing. The 94 GHz Cloud Profiling Radar onboard the ESA EarthCARE mission will be the first radar in space with Doppler capability allowing mean Doppler velocity measurements. This will enable more accurate characterization of clouds and precipitation (classification, retrieval accuracy, dynamics). It is the only instrument of this kind planned for the immediate post-CloudSat era and represents an irreplaceable asset in regards to climate change studies. Meeting the scientific accuracy requirements of vertical motions of 1 m/s, with a horizontal resolution of 1 km, is very challenging. The five key factors that control the performance of spaceborne radar will be discussed, such as: contribution of multiple scattering (MS), attenuation, velocity folding, non uniform beam filling (NUBF) and effects of along track integration of the signal. The research utilizes an end-to-end simulator for spaceborne Doppler radars. The simulator uses a Monte Carlo module which accounts for MS and produces ideal Doppler spectra as measured by a spaceborne radar flying over 3D highly resolved scenes produced via WRF Model simulations. The estimates of the Doppler moments (reflectivity, mean Doppler velocity and spectrum width) are achieved via the pulse pair technique. The objective method for identification of MS-contaminated range-bins based purely on the reflectivity-derived variables is described, with most important one, cumulative integrated reflectivity, found to be 41 dBZ_int which serves as the threshold value for identification of radar range gates contaminated by MS. This is further demonstrated in a CloudSat case study with the threshold value for CloudSat is found to be 41.9 dBZ_int. The unfolding procedure of Doppler velocities will be presented. Then we will describe the effects of the along track integration and achieved accuracy and biases of Doppler velocity for integration distance of 0.5, 1, 5 and 10 km. This will be complemented by correction of NUBF effect utilizing the along tract reflectivity gradient and velocity bias dependence.

Augustynek, T.; Battaglia, A.; Kollias, P.

2011-12-01

333

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

334

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.

335

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

336

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) and among the most research-intensive in Europe. Features * The Department of Earth and Environmental

Brierley, Andrew

337

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

338

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

339

An integrated simulation method for flash-flood risk assessment :2. Effect of historical changes in land use Hydrology and Earth System Sciences, 6(3), 285294 (2002) EGS  

E-print Network

in land use 285 Hydrology and Earth System Sciences, 6(3), 285­294 (2002) © EGS An integrated simulation method for flash-flood risk assessment: 2. Effects of changes in land-use under a historical perspective-mail for corresponding author: cristina.rulli@polimi.it Abstract The influence of land use changes on flood occurrence

Paris-Sud XI, Université de

340

From land use to land cover: Restoring the afforestation signal in a coupled integrated assessment - earth system model and the implications for CMIP5 RCP simulations  

SciTech Connect

Climate projections depend on scenarios of fossil fuel emissions and land use change, and the IPCC AR5 parallel process assumes consistent climate scenarios across Integrated Assessment and Earth System Models (IAMs and ESMs). To facilitate consistency, CMIP5 used a novel land use harmonization to provide ESMs with seamless, 1500-2100 land use trajectories generated by historical data and four IAMs. However, we have identified and partially addressed a major gap in the CMIP5 land coupling design. The CMIP5 Community ESM (CESM) global afforestation is only 22% of RCP4.5 afforestation from 2005 to 2100. Likewise, only 17% of the Global Change Assessment Model’s (GCAM’s) 2040 RCP4.5 afforestation signal, and none of the pasture loss, were transmitted to CESM within a newly integrated model. This is a critical problem because afforestation is necessary for achieving the RCP4.5 climate stabilization. We attempted to rectify this problem by modifying only the ESM component of the integrated model, enabling CESM to simulate 66% of GCAM’s afforestation in 2040, and 94% of GCAM’s pasture loss as grassland and shrubland losses. This additional afforestation increases vegetation carbon gain by 19 PgC and decreases atmospheric CO2 gain by 8 ppmv from 2005 to 2040, implying different climate scenarios between CMIP5 GCAM and CESM. Similar inconsistencies likely exist in other CMIP5 model results, primarily because land cover information is not shared between models, with possible contributions from afforestation exceeding model-specific, potentially viable forest area. Further work to harmonize land cover among models will be required to adequately rectify this problem.

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

2014-11-27

341

From land use to land cover: restoring the afforestation signal in a coupled integrated assessment-earth system model and the implications for CMIP5 RCP simulations  

NASA Astrophysics Data System (ADS)

Climate projections depend on scenarios of fossil fuel emissions and land use change, and the Intergovernmental Panel on Climate Change (IPCC) AR5 parallel process assumes consistent climate scenarios across integrated assessment and earth system models (IAMs and ESMs). The CMIP5 (Coupled Model Intercomparison Project Phase 5) project used a novel "land use harmonization" based on the Global Land use Model (GLM) to provide ESMs with consistent 1500-2100 land use trajectories generated by historical data and four IAMs. A direct coupling of the Global Change Assessment Model (GCAM), GLM, and the Community ESM (CESM) has allowed us to characterize and partially address a major gap in the CMIP5 land coupling design: the lack of a corresponding land cover harmonization. For RCP4.5, CESM global afforestation is only 22% of GCAM's 2005 to 2100 afforestation. Likewise, only 17% of GCAM's 2040 afforestation, and zero pasture loss, were transmitted to CESM within the directly coupled model. This is a problem because GCAM relied on afforestation to achieve RCP4.5 climate stabilization. GLM modifications and sharing forest area between GCAM and GLM within the directly coupled model did not increase CESM afforestation. Modifying the land use translator in addition to GLM, however, enabled CESM to include 66% of GCAM's afforestation in 2040, and 94% of GCAM's pasture loss as grassland and shrubland losses. This additional afforestation increases CESM vegetation carbon gain by 19 PgC and decreases atmospheric CO2 gain by 8 ppmv from 2005 to 2040, which demonstrates that CESM without additional afforestation simulates a different RCP4.5 scenario than prescribed by GCAM. Similar land cover inconsistencies exist in other CMIP5 model results, primarily because land cover information is not shared between models. Further work to harmonize land cover among models will be required to increase fidelity between IAM scenarios and ESM simulations and realize the full potential of scenario-based earth system simulations.

Di Vittorio, A. V.; Chini, L. P.; Bond-Lamberty, B.; Mao, J.; Shi, X.; Truesdale, J.; Craig, A.; Calvin, K.; Jones, A.; Collins, W. D.; Edmonds, J.; Hurtt, G. C.; Thornton, P.; Thomson, A.

2014-11-01

342

Integration  

ERIC Educational Resources Information Center

Integrated learning is an exciting adventure for both teachers and students. It is not uncommon to observe the integration of academic subjects such as math, science, and language arts. However, educators need to recognize that movement experiences in physical education also can be linked to academic curricula and, may even lead the…

Kalyn, Brenda

2006-01-01

343

Assessing environmental drivers of vegetation greenness by integrating multiple earth observation data in the LPJmL dynamic global vegetation model  

NASA Astrophysics Data System (ADS)

Recently produced satellite datasets of vegetation greenness demonstrate a widespread greening of the earth in the last three decades. These positive trends in vegetation greenness are related to changes in leaf area, vegetation cover and photosynthetic activity. Climatic changes, CO2 fertilization, disturbances and other land cover changes are potential drivers of these greening trends. Nevertheless, different satellite datasets show different magnitudes and trends in vegetation greenness. This fact raises the question about the reliability of these datasets. On the other hand, global vegetation models can be potentially used to assess the effects of environmental drivers on vegetation greenness and thus to explore the environmental reliability of these datasets. Unfortunately, current vegetation models have several weaknesses in reproducing observed temporal dynamics in vegetation greenness. Our aim is to integrate multiple earth observation data sets in a dynamic global vegetation model in order to 1) improve the model's capability to reproduce observed dynamics and spatial patterns of vegetation greenness and 2) to assess the spatial and temporal importance of environmental drivers for the seasonal to decadal variability of vegetation greenness. For this purpose, we developed a data integration system for the LPJmL dynamic global vegetation model (LPJmL-DIS). We implemented a new phenology scheme in LPJmL to better represent observed temporal dynamics of FAPAR (fraction of absorbed photosynthetic active radiation). Model parameters were globally optimized using a genetic optimization algorithm. The model optimization was performed globally against 30 year FAPAR time series (GIMMS3g dataset), against 10 year albedo time series (MODIS) and global patterns of gross primary production as up-scaled from FLUXNET eddy covariance measurements. Additionally, we directly prescribed satellite observations of land and tree cover in LPJmL to better represent global vegetation distribution by still keeping major processes of vegetation dynamics like mortality and competition among plant functional types. We prescribed observed burnt areas from the GFED dataset as well as from the Alaskan and Canadian national fire databases in LPJmL to better reproduce observed fire dynamics. We evaluated LPJmL with optimized parameters against independent data streams. LPJmL with a new phenology scheme and optimized parameters better represents spatial patterns of gross primary production, biomass, soil organic carbon, evapotranspiration and tree cover than the original model. LPJmL-DIS is able to reproduce spatial patterns and observed temporal dynamics of FAPAR from seasonal to decadal scales in all major biomes. We performed several model experiments to disentangle the spatial and temporal importance of temperature, radiation, water availability, CO2 fertilization, fire activity and permafrost changes on the seasonal to decadal variability of vegetation greenness. Our results indicate that water availability is a major driver for the seasonal to decadal variability of vegetation greenness in tropical, temperate and boreal biomes. The developed LPJmL data integration system enables to reanalyse recent trends in vegetation greenness and their environmental drivers by combining earth observation data of multiple environmental variables in a consistent process-based global vegetation model framework.

Forkel, Matthias; Carvalhais, Nuno; Schaphoff, Sibyll; von Bloh, Werner; Thurner, Martin; Thonicke, Kirsten

2014-05-01

344

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

345

Multi-kilowatt, all-fiber integrated chirped-pulse amplification system yielding 40x pulse compression using air-core fiber and conventional erbium-doped fiber amplifier.  

PubMed

We present a totally fiber integrated chirped-pulse amplification system using air-core photonic bandgap fiber and a conventional erbium-doped fiber amplifier. ~40-ps input pulses, generated in a Mach-Zehnder modulator, were stretched and spectrally broadened in a dispersion-shifted fiber before being amplified and subsequently compressed in 10 m of anomalously-dispersive photonic bandgap fiber to yield ~960 fs pulses. The system gives multi-kilowatt peak powers while the amplifier nonlinearity threshold is as low as ~150 W. Higher peak powers could be obtained by the use of an amplifier with higher nonlinearity threshold. PMID:19474837

de Matos, C; Taylor, J

2004-02-01

346

Ion implanted optical channel waveguides in Er3+/MgO co-doped near stoichiometric LiNbO3: a new candidate for active integrated photonic devices operating at 1.5 microm.  

PubMed

We report on the fabrication of active optical channel waveguides in Er(3+)/MgO co-doped near stoichiometric lithium niobate crystals by means of selective low-dose oxygen ion implantation through a specially designed photoresist stripe mask. After post-implantation treatment at 260 degrees C for 1 h, the channel waveguides possess a propagation loss of approximately 1.7 dB/cm. The micro-luminescence investigation reveals that fluorescence emissions at approximately 1.5 microm in the waveguides are well preserved with respect to the bulk, exhibiting possible applications for integrated active photonic devices. PMID:18825260

Chen, Feng; Tan, Yang; Ródenas, Airán

2008-09-29

347

Integration of light attenuation measurements from Earth Observation into 3D Geobiochemical models of the North Sea.  

NASA Astrophysics Data System (ADS)

The FP7 CoBiOS project aims to develop a near-real-time information system to diagnose high-biomass blooms in the Baltic Sea and North Sea. The core information in such a system will result from integration of ocean colour remote sensing with 3D geobiochemical modelling. A key parameter is the description of available solar energy in these complex waters, where optically active substances such as silt, algae and dissolved organic material all contribute to the light extinction. A new approach is presented to consistently define the light extinction coefficient Kd of the downward irradiance over PAR from an EO perspective and a numerical modelling perspective. An analysis of a few hundred in-situ Kd-profiles in the North Sea demonstrates that irradiance extinction by the various substances as a function of their PAR-representative absorption and scattering properties works better than a linear model of 'specific extinction' coefficients. In addition to adopting consistent coefficients, it is recommended to apply a nonlinear approach to couple absorption and scattering properties for deriving Kd [1,2]. This approach enables obtaining a consistently defined set of Kd values that will facilitate assimilation of geobiochemical models with ocean colour observations. [1] Lee, Z.P., Du, K.P., Arnone, R. 2005. A model for the diffuse attenuation coefficient of downwelling irradiance J. Geophys. Res., 110, C02016, doi:10.1029/2004JC002275, 2005 [2] Van der Woerd, H.J., Pasterkamp, R. 2008. HYDROPT: A fast and flexible method to retrieve chlorophyll-a from multi-spectral satellite observation of optical-complex coastal waters. Rem. Sens. Env. 112, 1795-1807

van der Woerd, Hans; Blaas, Meinte; Peters, Steef W. M.; Eleveld, Marieke; Garcia Triana, Ivan D. T. F.

2013-04-01

348

Earth's Seasons  

NSDL National Science Digital Library

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

Rochester Museum And Science Center, Strasenburgh P.

349

Edible Earth  

NSDL National Science Digital Library

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

American Museum of Natural History

2011-08-20

350

Earth Flow  

NSDL National Science Digital Library

This Flash animation with accompanying audio exhibits the different stages involved in the formation of an earth flow. A step-like scarp forms along with a flowage zone at the toe of the earth flow. The sequence concludes with the stabilization of the earth flow with vegetation. Expect long loading times.

Wiley

351

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.

352

Earth Calendar  

NSDL National Science Digital Library

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

Barker, Jeffrey

353

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."

354

Integration  

NSDL National Science Digital Library

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

2013-06-21

355

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

356

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

357

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

SciTech Connect

Significant progress has been made in synthesizing and characterizing ultra-pure, rare-earth doped ZIBLAN (ZrF{sub 4}-InF{sub 3}BaF{sub 2}-LaF{sub 3}-AlF{sub 3}-NaF) glass capable of laser refrigeration. The glass was produced from fluorides which were purified and subsequently treated with hydrofluoric gas at elevated temperatures to remove impurities before glass formation. Several Yb3 +-doped samples were studied with degrees of purity and composition with successive iterations producing an improved material. We have developed a non-invasive, spectroscopic technique, two band differential luminescence thermometry (TBDLT), to evaluate the intrinsic quality of the ytterbium doped ZIBLAN used for laser cooling experiments. TBDLT measures local temperature changes within an illuminated volume resulting solely from changes in the relative thermal population of the excited state levels. This TBDLT technique utilizes two commercially available band pass filters to select and integrate the 'difference regions' of interest in the luminescence spectra. The goal is to determine the minimum temperature to which the ytterbium sample can cool on the local scale, unphased by surface heating. This temperature where heating and cooling are exactly balanced is the zero crossing temperature (ZCT) and can be used as a measure for the presence of impurities and the overall quality of the laser cooling material. Overall, favorable results were obtained from 1 % Yb3+-doped glass, indicating our glasses are desirable for laser refrigeration.

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

2009-01-01

358

Dynamic Earth  

NSDL National Science Digital Library

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

Ashlinn Quinn

2007-01-01

359

Celebrate Earth  

NSDL National Science Digital Library

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

Mrs. Rokes

2009-04-23

360

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.

361

Earth Day  

NSDL National Science Digital Library

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

362

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

E-print Network

of the proposed laser at around 810 nm in three different hosts: fluoride glass (ZBLAN), standard silicaTheoretical analysis of fiber lasers emitting around 810 nm based on thulium-doped silica fibers-earth doped fiber lasers are situated around 1, 1.5 and 2 µm. In this paper we investigate thulium-doped fiber

Boyer, Edmond

363

Song of the Earth  

NSDL National Science Digital Library

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

364

From land use to land cover: restoring the afforestation signal in a coupled integrated assessment - earth system model and the implications for CMIP5 RCP simulations  

NASA Astrophysics Data System (ADS)

Climate projections depend on scenarios of fossil fuel emissions and land use change, and the IPCC AR5 parallel process assumes consistent climate scenarios across Integrated Assessment and Earth System Models (IAMs and ESMs). The CMIP5 project used a novel "land use harmonization" based on the Global Land use Model (GLM) to provide ESMs with consistent 1500-2100 land use trajectories generated by historical data and four IAM projections. A direct coupling of the Global Change Assessment Model (GCAM), GLM, and the Community ESM (CESM) has allowed us to characterize and partially address a major gap in the CMIP5 land coupling design: the lack of a corresponding land cover harmonization. The CMIP5 CESM global afforestation is only 22% of GCAM's 2005 to 2100 RCP4.5 afforestation. Likewise, only 17% of GCAM's 2040 RCP4.5 afforestation, and zero pasture loss, were transmitted to CESM within the directly coupled model. This is a problem because afforestation was relied upon to achieve RCP4.5 climate stabilization. GLM modifications within the directly coupled model did not increase CESM afforestation. Modifying the land use translator in addition to GLM, however, enabled CESM to simulate 66% of GCAM's afforestation in 2040, and 94% of GCAM's pasture loss as grassland and shrubland losses. This additional afforestation increases vegetation carbon gain by 19 PgC and decreases atmospheric CO2 gain by 8 ppmv from 2005 to 2040, implying different RCP4.5 climate scenarios between CMIP5 GCAM and CESM. Although the IAMs and ESMs were not expected to have exactly the same climate forcing, due in part to different terrestrial carbon cycles and atmospheric radiation algorithms, the ESMs were expected to project climates representative of the RCP scenarios. Similar land cover inconsistencies exist in other CMIP5 model results, primarily because land cover information is not shared between models. High RCP4.5 afforestation might also contribute to inconsistencies as some ESMs might impose bioclimatic limits to potential forest area and have different rates of forest growth than projected by RCP4.5. Further work to harmonize land cover among models will be required to address this problem.

Di Vittorio, A. V.; Chini, L. P.; Bond-Lamberty, B.; Mao, J.; Shi, X.; Truesdale, J.; Craig, A.; Calvin, K.; Jones, A.; Collins, W. D.; Edmonds, J.; Hurtt, G. C.; Thornton, P.; Thomson, A.

2014-05-01

365

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

366

Earth meandering  

Microsoft Academic Search

In this paper we try to put away current Global Tectonic Model to look the tectonic evolution of the earth from new point of view. Our new dynamic model is based on study of river meandering (RM) which infer new concept as Earth meandering(EM). In a universal gravitational field if we consider a clockwise spiral galaxy model rotate above Ninety

H. Asadiyan; A. Zamani

2009-01-01

367

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

368

Time-delay-and-integration charge coupled devices /CCDs/ applied to the Thematic Mapper. [onboard Landsat  

NASA Technical Reports Server (NTRS)

The visible focal plane of the Thematic Mapper, the next generation sensor system for application to earth resource survey, uses complex hybrid assembly techniques to interface silicon photodiodes to JFET preamplifiers. This complexity can be ameliorated by the use of a 20-channel time-delay-and-integration (TDI) CCD with nine stages of integration per channel. By going to a CCD array operating in a TDI mode, over 700 individual op amps can be replaced with only 48 op amps. Smooth spectral response and 70% quantum efficiency have been provided by using doped tin oxide gates over the imaging region.

Thompson, L. L.; Mccann, D. H.

1978-01-01

369

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

370

Preparation by PVD of Er/Ce-doped PZG fluoride glass channel waveguide for integrated optical amplifiers at 1.5 ?m  

NASA Astrophysics Data System (ADS)

The fabrication by physical vapor deposition (PVD) of Er/Ce-doped fluoride glass channel waveguides using low cost silica on silicon (SiO 2/Si) engraved cleavable substrates was demonstrated. The mean composition of the deposited glass was 38PbF 2-19ZnF 2-43GaF 3 in mol% with Er and Ce concentrations fixed at 1 mol%. The channel waveguides with cross-sectional dimensions 3 × 2 ?m 2 were single-mode at 0.63 ?m. Propagation losses of less than 0.5 dB/cm and loss reduction of 3.3 dB/cm were measured at 1.535 ?m in a 3.2 cm long waveguide with an absorbed power of about 3 mW at 0.98 ?m.

Gao, Youping; Boulard, Brigitte; Couchaud, Maurice; Vasilief, Ion; Guy, Stéphan; Duverger, Claire; Jacquier, Bernard

2006-02-01

371

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.

Houghton Mifflin Science

372

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.

Houghton Mifflin Science

373

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

374

Earth Day  

NSDL National Science Digital Library

The State University of New York at Buffalo presents this History of Earth Day website. The goal of the site is that teachers and students can better understand the development and purpose of Earth Day. In addition to the history, SUNY-Buffalo has compiled a series of websites complete with projects associated with Earth Day, appropriate for children, high school students, and college undergrads. Furthermore, the legal aspect of Earth Day - environmental legislation, EPA standards, and Global Climate Change legislation - are also discussed on the site. A list of further sites is also provided if users want more information on this national effort to help solve environmental issues such as pollution, overpopulation, and global warming. Teachers will find this website both informative and helpful in developing appropriate teaching curricula connected to this holiday, while students can have fun learning and creating projects of their own that contribute to preserving the environment.

2007-04-19

375

Visible Earth  

NSDL National Science Digital Library

This site provides a searchable collection of NASA Earth science images, animations and data visualizations. Most images are available at multiple resolutions, with a description of the image and metadata. Users can search the database using full text; or with advanced searches by topic, keyword, sensor, geographic region, parameter, and dates. Examples of topics represented in this collection are snow and ice, agriculture, oceans, climate, the atmosphere, human dimensions, land surface, the solid earth and more.

NASA

376

Integration of Multiple OGC Standards for Delivery of Earth Science Information - Presentation of Time-Enabled WMS Through KML as Implemented by the PHAiRS Project  

Microsoft Academic Search

Since 2004 the Earth Data Analysis Center has, in collaboration with researchers from the University of Arizona and George Mason University, with funding from NASA, developed a services oriented architecture (SOA) designed for the delivery of historic and current dust forecast data products to the public health user community. This system has generated nearly three years of daily 48-hour dust

W. B. Hudspeth; K. K. Benedict

2008-01-01

377

National Aeronautics and Space Administration Earth Science at NASA  

E-print Network

National Aeronautics and Space Administration Earth Science at NASA November 10, 2009 www­7 Years 16 Appendix A--Earth Science Missions Currently In Operation 21 Appendix B--Earth Science continues to lead the international scientific community to advance global integrated Earth system science

Christian, Eric

378

Erbium-doped nanoparticles in silica-based optical fibres  

E-print Network

Developing of new rare-earth (RE)-doped optical fibres for power amplifiers and lasers requires continuous improvements in the fibre spectroscopic properties (like shape and width of the gain curve, optical quantum efficiency, resistance to spectral hole burning and photodarkening...). Silica glass as a host material for fibres has proved to be very attractive. However, some potential applications of RE-doped fibres suffer from limitations in terms of spectroscopic properties resulting from clustering or inappropriate local environment when doped into silica. To this aim, we present a new route to modify some spectroscopic properties of RE ions in silica-based fibres based on the incorporation of erbium ions in amorphous dielectric nanoparticles, grown in-situ in fibre preforms. By adding alkaline earth elements, in low concentration into silica, one can obtain a glass with an immiscibility gap. Then, phase separation occurs under an appropriate heat treatment. We investigated the role of three alkaline-earth...

Blanc, Wilfried; Dussardier, Bernard; 10.1504/IJNT.2012.045350

2012-01-01

379

Erbium-doped Lithium Niobate waveguide lasers: recent progress  

E-print Network

Erbium-doped Lithium Niobate waveguide lasers: recent progress W. Sohler, D. Dey, B. Das, S. Reza, Warburger Str. 100, 33098 Paderborn, Germany ABSTRACT Erbium diffusion doping of LiNbO3 (e.g. 30 nm / 1130 achieved with an output power up to 150 µW. Keywords: Erbium, Lithium Niobate, integrated optics, waveguide

Mohseni, Hooman

380

Rotation of a Moonless Earth  

NASA Technical Reports Server (NTRS)

We numerically explore the obliquity (axial tilt) variations of a hypothetical moonless Earth. Previous work has shown that the Earth's Moon stabilizes Earth's obliquity such that it remains within a narrow range, between 22.1 deg and 24.5 deg. Without lunar influence, a frequency-map analysis by Laskar et al. showed that the obliquity could vary between 0 deg. and 85 deg. This has left an impression in the astrobiology community that a large moon is necessary to maintain a habitable climate on an Earth-like planet. Using a modified version of the orbital integrator mercury, we calculate the obliquity evolution for moonless Earths with various initial conditions for up to 4 Gyr. We find that while obliquity varies significantly more than that of the actual Earth over 100,000 year timescales, the obliquity remains within a constrained range, typically 20-25 deg. in extent, for timescales of hundreds of millions of years. None of our Solar System integrations in which planetary orbits behave in a typical manner show obliquity accessing more than 65% of the full range allowed by frequency-map analysis. The obliquities of moonless Earths that rotate in the retrograde direction are more stable than those of pro-grade rotators. The total obliquity range explored for moonless Earths with rotation periods shorter than 12 h is much less than that for slower-rotating moonless Earths. A large moon thus does not seem to be needed to stabilize the obliquity of an Earth-like planet on timescales relevant to the development of advanced life.

Lissauer, Jack J.; Barnes, Jason W.; Chambers, John E.

2013-01-01

381

An approach to integrated assessement of reservoir siltation: the Joaqun Costa reservoir as a case study Hydrology and Earth System Sciences, 8(6), 11931199 (2004) EGU  

E-print Network

An approach to integrated assessement of reservoir siltation: the Joaquín Costa reservoir as a case to integrated assessement of reservoir siltation: the Joaquín Costa reservoir as a case study A. Navas1 , B Costa reservoir has been based on detailed sedimentological examination and other analysis of mineralogy

Paris-Sud XI, Université de

382

Discover Earth: Earth's Energy Budget or Can You Spare a Sun?  

NASA Technical Reports Server (NTRS)

Discover Earth is a NASA-sponsored project for teachers of grades 5-12, designed to: enhance understanding of the Earth as an integrated system enhance the interdisciplinary approach to science instruction, and provide classroom materials that focus on those goals. Discover Earth is conducted by the Institute for Global Environmental Strategies in collaboration with Dr. Eric Barron, Director, Earth System Science Center, The Pennsylvania State University; and Dr. Robert Hudson, Chair, the Department of Meteorology, University of Maryland at College Park.

Gates, Tom; Peters, Dale E.; Steeley, Jeanne

1999-01-01

383

Savage Earth  

NSDL National Science Digital Library

The Savage Earth website is the on-line companion to the PBS television series of the same name. This site tells the stories of several great natural disasters, particularly the eruption of Mt. Vesuvius in 79 A.D. that destroyed Pompeii and the 1994 earthquake in Kobe, Japan. It contains articles on the earth's crust and plate tectonics, earthquakes, volcanoes, and tsunamis. Each article features photographs, animated drawings, and video clips. For example, the earthquakes article includes animations of types of faults and three different kinds of seismic waves. There is also a question and answer section and links to related sites about geology and natural hazards.

2002-04-24

384

Ab-initio calculation of magnetic properties of Gd-doped ZnGeN2  

Microsoft Academic Search

The current interest in the field of semiconductor spintronics is mostly focused on transition metal-doped and rare-earth metal-doped binary materials. Recently, however, the explorations of metal-doped ternary semiconductors have gained attention due to experimental confirmations of possible high transition temperature in chalcopyrite compounds. Since the chalcopyrites are ternary materials, there are possibilities of having ferromagnetic or antiferromagnetic configurations, depending on

J. Rufinus

2011-01-01

385

Earth observing system: 1989 reference handbook  

NASA Technical Reports Server (NTRS)

NASA is studying a coordinated effort called the Mission to Planet Earth to understand global change. The goals are to understand the Earth as a system, and to determine those processes that contribute to the environmental balance, as well as those that may result in changes. The Earth Observing System (Eos) is the centerpiece of the program. Eos will create an integrated scientific observing system that will enable multidisciplinary study of the Earth including the atmosphere, oceans, land surface, polar regions, and solid Earth. Science goals, the Eos data and information system, experiments, measuring instruments, and interdisciplinary investigations are described.

1989-01-01

386

Digital Earth - A sustainable Earth  

NASA Astrophysics Data System (ADS)

All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth.

Mahavir

2014-02-01

387

Earth's Water  

NSDL National Science Digital Library

This resource provides an overview of the distribution and occurence of water on Earth. Topics include where and how much water there is, the water cycle, and how water is measured. There is also discussion of characteristics and distribution of surface water, groundwater, glaciers, and icecaps.

388

Earth Structures  

NSDL National Science Digital Library

This web guide explores several natural phenomena that are constantly changing the face of the Earth. These geologic forces not only impact the physical features of our planet but ultimately affect the biosphere in a dramatic way. Historically, the changes have ranged from gradual (such as with the process of mountain building) to the spontaneous (such as with seismic events).

National Science Teachers Association (NSTA)

2005-04-01

389

Earth Movers  

NSDL National Science Digital Library

This lesson explores plate tectonics and helps students understand how mountains, earthquakes, and volcanoes are related to the movements of plates. Students will learn about the idea of continental drift and the theory of plate tectonics to ascertain a fuller picture of how land formations on the surface of the Earth are shaped by plates moving below the surface.

390

Visible Earth  

NSDL National Science Digital Library

This Web site provides a searchable directory of NASA Earth science images, animations and data visualizations. Most resources are available digitally at multiple resolutions, with captions and metadata. Users can search the database using full text and advanced searches by topic, keyword, sensor, location, parameter, and dates.

2001-01-01

391

Impact Earth  

NSDL National Science Digital Library

This planetarium show teaches about meteors, meteorites, asteroids, and comets. It includes results from NASA missions and about the dangers they can pose to life on Earth. It is created for full-dome theaters but can also be shown in flat version for TVs and computer monitors. Shows the effects of the Chixulub and Tungusta events, plus the Pallasite impact that resulted in the Brenham meteorite fall. Describes ways that asteroid hunters seek new objects in the Solar System, and how ground-penetrating radar is used to find meteorites that have reached the Earth's surface and ancient craters under the desert. Narrated by astronaut Tom Jones, it also discusses ways that humans might try to deflect an asteroid or comet that is on a collision course with Earth. Created for informal science venues (digital planetariums), it is also useful as ancillary material for middle school science. Created under NASA Cooperative Agreement NCC5-316 to Rice University in conjunction with the Houston Museum of Natural Science as part of the "Immersive Earth" project, part of the REASoN program.

Reiff, Patricia

2009-05-01

392

Properties of an Earth-Like Planet Orbiting a Sun-Like Star: Earth Observed by the EPOXI Mission  

E-print Network

NASA's EPOXI mission observed the disc-integrated Earth and Moon to test techniques for reconnoitering extrasolar terrestrial planets, using the Deep Impact flyby spacecraft to observe Earth at the beginning and end of ...

Livengood, Timothy A.

393

Orthorhombic superstructures within the rare earth strontium-doped cobaltate perovskites: Ln{sub 1-x}Sr{sub x}CoO{sub 3-{delta}} (Ln=Y{sup 3+}, Dy{sup 3+}-Yb{sup 3+}; 0.750{<=}x{<=}0.875)  

SciTech Connect

A combination of electron, synchrotron X-ray and neutron powder diffraction reveals a new orthorhombic structure type within the Sr-doped rare earth perovskite cobaltates Ln{sub 1-x}Sr{sub x}CoO{sub 3-{delta}} (Ln=Y{sup 3+}, Dy{sup 3+}, Ho{sup 3+}, Er{sup 3+}, Tm{sup 3+}and Yb{sup 3+}). Electron diffraction shows a C-centred cell based on a 2{radical}2a{sub p}x4a{sub p}x4{radical}2a{sub p} superstructure of the basic perovskite unit. Not all of these very weak satellite reflections are evident in the synchrotron X-ray and neutron powder diffraction data and the average structure of each member of this series could only be refined based on Cmma symmetry and a 2{radical}2a{sub p}x4a{sub p}x2{radical}2a{sub p} cell. The nature of structural and magnetic ordering in these phases relies on both oxygen vacancy and cation distribution. A small range of solid solution exists where this orthorhombic structure type is observed, centred roughly around the compositions Ln{sub 0.2}Sr{sub 0.8}CoO{sub 3-{delta}}. In the case of Yb{sup 3+} the pure orthorhombic phase was only observed for 0.850{<=}x{<=}0.875. Tetragonal (I4/mmm; 2a{sub p}x2a{sub p}x4a{sub p}) superstructures were observed for compositions having higher or lower Sr-doping levels, or for compounds with rare earth ions larger than Dy{sup 3+}. These orthorhombic phases show mixed valence (3+/4+) cobalt oxidation states between 3.2+ and 3.3+. DC magnetic susceptibility measurements show an additional magnetic transition for these orthorhombic phases compared to the associated tetragonal compounds with critical temperatures > 330 K. - Graphical abstract: A study using electron, high-resolution synchrotron X-ray and neutron powder diffraction reveals a new family of orthorhombic perovskite superstructures (Ln{sub 0.2}Sr{sub 0.8}CoO{sub 3-{delta}}), that shows A-site (Ln{sup 3+}/Sr{sup 2+}) cation ordering as well as oxygen vacancy ordering.

James, Michael [Bragg Institute, Building 87, Australian Nuclear Science and Technology Organisation, PMB 1, Menai NSW 2234 (Australia)], E-mail: mja@ansto.gov.au; Avdeev, Maxim [Bragg Institute, Building 87, Australian Nuclear Science and Technology Organisation, PMB 1, Menai NSW 2234 (Australia); Barnes, Paris [Materials Science Division, MSD 223, Argonne National Laboratory, Argonne, IL 60439 (United States); Morales, Liliana [Bragg Institute, Building 87, Australian Nuclear Science and Technology Organisation, PMB 1, Menai NSW 2234 (Australia); Wallwork, Kia [Australian Synchrotron, 800 Blackburn Road, Clayton, Vict. 3168 (Australia); Withers, Ray [Research School of Chemistry, Australian National University, Canberra 0200, ACT (Australia)

2007-08-15

394

Coherent properties of single rare-earth spin qubits  

E-print Network

Rare-earth-doped crystals are excellent hardware for quantum storage of optical information. Additional functionality of these materials is added by their waveguiding properties allowing for on-chip photonic networks. However, detection and coherent properties of rare-earth single-spin qubits have not been demonstrated so far. Here, we present experimental results on high-fidelity optical initialization, effcient coherent manipulation, and optical readout of a single electron spin of Ce$^{3+}$ ion in a YAG crystal. Under dynamic decoupling, spin coherence lifetime reaches $T_2$=2 ms and is almost limited by the measured spin-lattice relaxation time $T_1$=3.8 ms. Strong hyperfine coupling to aluminium nuclear spins suggests that cerium electron spins can be exploited as an interface between photons and long-lived nuclear spin memory. Combined with high brightness of Ce$^{3+}$ emission and a possibility of creating photonic circuits out of the host material, this makes cerium spins an interesting option for integrated quantum photonics.

P. Siyushev; K. Xia; R. Reuter; M. Jamali; N. Zhao; N. Yang; C. Duan; N. Kukharchyk; A. D. Wieck; R. Kolesov; J. Wrachtrup

2014-05-20

395

Coherent properties of single rare-earth spin qubits  

NASA Astrophysics Data System (ADS)

Rare-earth-doped crystals are excellent hardware for quantum storage of photons. Additional functionality of these materials is added by their waveguiding properties allowing for on-chip photonic networks. However, detection and coherent properties of rare-earth single-spin qubits have not been demonstrated so far. Here we present experimental results on high-fidelity optical initialization, effcient coherent manipulation and optical readout of a single-electron spin of Ce3+ ion in a yttrium aluminium garnet crystal. Under dynamic decoupling, spin coherence lifetime reaches T2=2?ms and is almost limited by the measured spin-lattice relaxation time T1=4.5?ms. Strong hyperfine coupling to aluminium nuclear spins suggests that cerium electron spins can be exploited as an interface between photons and long-lived nuclear spin memory. Combined with high brightness of Ce3+ emission and a possibility of creating photonic circuits out of the host material, this makes cerium spins an interesting option for integrated quantum photonics.

Siyushev, P.; Xia, K.; Reuter, R.; Jamali, M.; Zhao, N.; Yang, N.; Duan, C.; Kukharchyk, N.; Wieck, A. D.; Kolesov, R.; Wrachtrup, J.

2014-05-01

396

Coherent properties of single rare-earth spin qubits.  

PubMed

Rare-earth-doped crystals are excellent hardware for quantum storage of photons. Additional functionality of these materials is added by their waveguiding properties allowing for on-chip photonic networks. However, detection and coherent properties of rare-earth single-spin qubits have not been demonstrated so far. Here we present experimental results on high-fidelity optical initialization, efficient coherent manipulation and optical readout of a single-electron spin of Ce(3+) ion in a yttrium aluminium garnet crystal. Under dynamic decoupling, spin coherence lifetime reaches T2 = 2 ms and is almost limited by the measured spin-lattice relaxation time T1 = 4.5 ms. Strong hyperfine coupling to aluminium nuclear spins suggests that cerium electron spins can be exploited as an interface between photons and long-lived nuclear spin memory. Combined with high brightness of Ce(3+) emission and a possibility of creating photonic circuits out of the host material, this makes cerium spins an interesting option for integrated quantum photonics. PMID:24826968

Siyushev, P; Xia, K; Reuter, R; Jamali, M; Zhao, N; Yang, N; Duan, C; Kukharchyk, N; Wieck, A D; Kolesov, R; Wrachtrup, J

2014-01-01

397

Earth meandering  

NASA Astrophysics Data System (ADS)

In this paper we try to put away current Global Tectonic Model to look the tectonic evolution of the earth from new point of view. Our new dynamic model is based on study of river meandering (RM) which infer new concept as Earth meandering(EM). In a universal gravitational field if we consider a clockwise spiral galaxy model rotate above Ninety East Ridge (geotectonic axis GA), this system with applying torsion field (likes geomagnetic field) in side direction from Rocky Mt. (west geotectonic pole WGP) to Tibetan plateau TP (east geotectonic pole EGP),it seems that pulled mass from WGP and pushed it in EGP due to it's rolling dynamics. According to this idea we see in topographic map that North America and Green land like a tongue pulled from Pacific mouth toward TP. Actually this system rolled or meander the earth over itself fractaly from small scale to big scale and what we see in the river meandering and Earth meandering are two faces of one coin. River transport water and sediments from high elevation to lower elevation and also in EM, mass transport from high altitude-Rocky Mt. to lower altitude Himalaya Mt. along 'S' shape geodetic line-optimum path which connect points from high altitude to lower altitude as kind of Euler Elastica(EE). These curves are responsible for mass spreading (source) and mass concentration (sink). In this regard, tiltness of earth spin axis plays an important role, 'S' are part of sigmoidal shape which formed due to intersection of Earth rolling with the Earth glob and actual feature of transform fault and river meandering. Longitudinal profile in mature rivers as a part of 'S' curve also is a kind of EE. 'S' which bound the whole earth is named S-1(S order 1) and cube corresponding to this which represent Earth fracturing in global scale named C-1(cube order 1 or side vergence cube SVC), C-1 is a biggest cycle of spiral polygon, so it is not completely closed and it has separation about diameter of C-7. Inside SVC we introduce cone vergence cube (CVC or geotectonic equator GE) which rotate 45 degree counterclockwise with respect to SVC. Every cube from big scale to small scale fractalize in order of 23 and every '8' shape from big scale to small scale also fractalize in the same order. Three dimensional and fractoscopic imagination about understanding the changing on earth is very important so we should imagine '8' as curved surface, sea floor spreading happened in maximum curvature of these surfaces. '8' formed from pair 'S' string with opposite direction. '8' oscillate in Pole-Pole and Side-Side direction and have saddle geometry with two 'U' path along perpendicular saddle (e.g. Lut/Jazmurian and Helmand/Mashkal basin in Iran actually intersection of this saddle shape with the earth surface and Iceland /Black Sea and CapeVerde/Victoria Lake are also In/Out (small scale polygon) of 'U' shape conduit which followed axial saddle of Side-'S-2' and Okhotsk Sea /Balkhash Lake followed axial saddle conduit of Pole-'S-2' actually intersection of this perpendicular conduit with surface make spot-like-lakes/volcanoes or basin. Global EM in Side-S-1 bounded compression region-TP inside and tension region-East African Rift offside).This is a interesting competing between two kinematic geometry - spherical and isometrical geometry by using the interaction of them we can analyze the earth face in past, present and future apart of the forces that cause this face. C-1 in two dimensional look like six sided big tent which speared over Tibet and main rod driven along GA. Pair S-1 curve. have seven component(fold) and six segment in between,S-7 exactly located on TP(center of S-1). Between two successive fold we have complex geology(e.g. eastern Iran and Afghanistan)mass dragged from North America and Siberian and accumulated gradually during six step in Earth Foundation(Tibet),S-7 bounded Takla Makan Desert (in smaller loop) and TP (in bigger loop) S-7 alter the earth balance and responsible for earth disturbing, another sample of 'S' curve we see around Australia and Kermadec/Tonga Trench, Aleutian ri

Asadiyan, H.; Zamani, A.

2009-04-01

398

An Integrative Approach to Improving an Introductory Weather & Climate Course and Developing an Allied NASA Earth & Space Science Certificate Program for Pre-service Secondary Teachers (Invited)  

NASA Astrophysics Data System (ADS)

An Atlanta-based partnership made up of leaders in science, education, and Georgia’s state-wide STEM Education Initiative are creating an enduring legacy of climate science education for pre-service and in-service teachers in Georgia as well as for underrepresented high school students who participate in an "Early College" program with Georgia State University (GSU). The core elements of our NASA-funded program are to infuse NASA global climate change resources and best pedagogical practice into a popular 4-credit lecture/lab course called “Introduction to Weather & Climate” (GEOG 1112) at GSU, and to establish a sustainable academic program for pre-service teachers in the College of Education called the NASA Earth & Space Science (ESS) Teacher Certificate. The NASA ESS Certificate will require candidates to accomplish the following as part of (or in addition to) standard degree and licensure requirements: 1. successfully complete a graduate section of “Introduction to Weather and Climate” (GEOG 7112), which requires lesson planning related to course content and engagement with GSU's new CO2 monitoring station whose research-quality data will provide unique hands-on opportunities for Metro Atlanta students and teachers; 2) complete an additional advanced course in climate change (GEOG 6784) plus elective hours in physical science disciplines (e.g. astronomy and physics); 3) serve as a lab teaching assistant for GEOG 1112 and a coach for a cadre of Carver Early College students who are taking the course; 4) make at least one of two teaching practica at a Georgia-based NASA Explorer School; and 5) participate or co-present in a week-long, residential, field-based, Summer Institute in Earth & Space Science intended to increase the interest, knowledge, and ability of in-service secondary science educators to fulfill climate-related standards in Earth Science and Earth Systems Science. We will evaluate, document, and disseminate (to the University System of Georgia and beyond) our model for the NASA-enhancement of an introductory science course as a focal point for teacher preparation and professional development.

Morrow, C. A.; Martin-Hansen, L.; Diem, J.; Elliott, W.

2009-12-01

399

Save the Earth vs Destroy the Earth  

E-print Network

Abstract. Save the Earth VS Destroy the Earth is an interactive installation. Two structures, built with the skeletons of old monitors, are holding two world globes, plus a sign indicating on one Save the Earth and on the other Destroy the Earth. The audience is invited to mime the action to save or destroy the Earth becoming a part of the artwork. Every action is monitored and photographed, leading to the creation of an image dataset of save-the-earth vs destroy-the-earth actions. Such dataset can be interpreted as sort of sentiment dataset, where actors express a negative or positive sentiment about the "Save the Earth " topic.

Davide Giaccone

400

SolidEarth: a new Digital Earth system for the modeling and visualization of the whole Earth space  

NASA Astrophysics Data System (ADS)

Although many of the first-generation Digital Earth systems have proven to be quite useful for the modeling and visualization of geospatial objects relevant to the Earth's surface and near-surface, they were not designed for the purpose of modeling and application in geological or atmospheric space. There is a pressing need for a new Digital Earth system that can process geospatial information with full dimensionality. In this paper, we present a new Digital Earth system, termed SolidEarth, as an alternative virtual globe for the modeling and visualization of the whole Earth space including its surface, interior, and exterior space. SolidEarth consists of four functional components: modeling in geographical space, modeling in geological space, modeling in atmospheric space, and, integrated visualization and analysis. SolidEarth has a comprehensive treatment to the third spatial dimension and a series of sophisticated 3D spatial analysis functions. Therefore, it is well-suited to the volumetric representation and visual analysis of the inner/ outer spheres in Earth space. SolidEarth can be used in a number of fields such as geoscience research and education, the construction of Digital Earth applications, and other professional practices of Earth science.

Zhu, Liangfeng; Sun, Jianzhong; Li, Changling; Zhang, Bing

2014-12-01

401

Breathing Earth  

NSDL National Science Digital Library

Visual simulation and representation programs and applications have been popping up online in greater numbers, and this recent find is one that will pique the interest of scientists, policy makers, and others who are concerned about carbon dioxide emission rates across the Earth. The Breathing Earth site was created by David Bleja, and he draws on a number of resources (such as the World Factbook and the United Nations) for the data that is utilized to create this site. Visitors can scroll over different countries to learn about their population, their emissions, and their birth and death rate. This interactive map and educational resource also contains a legend in the right-hand corner which explains the various symbols in use here.

Bleja, David

402

Earth Math  

NSDL National Science Digital Library

This text explores a few of the many concepts that frequently come up in the study of Earth systems and global climate change. Students will be exposed to many problems involving unit conversion. Global climate change reports involve terms such as kilowatt-hour, megawatt-hour, and gigawatt-hour, as well as megatons and gigatons. Students will become versed in converting units where appropriate, and through the calculations, will work with the concept of significant figures. Creating linear equations from graphical and tabular information is covered, as well as forecasting. The text is meant to be used as a companion to standard Earth science and mathematics courses, and presents enough application problems to allow students to quantitatively understand typical media reports about global climate change.

2009-01-01

403

Impact: Earth!  

NSDL National Science Digital Library

What would happen if a large meteorite or other object hit the Earth? It's something that has engaged the minds and talents of astrophysicists (and students of all ages) for decades. Now the generally curious can create their own simulated impact with Purdue University's "Impact Earth" website. Visitors can browse the Famous Craters area to get started. This part includes some "classics," such as the Ries Crater and the Tunguska Fireball. Of course, visitors really must use the handy interface to craft their own impact, projectile, and target parameters to get the full effect on how such an event plays out. Also, the site includes a complete Documentation file (a peer-reviewed article) and a detailed glossary.

2013-01-01

404

Earth Lab  

NSDL National Science Digital Library

Earth Lab is a database of fossils, minerals and rocks from the UK. A photograph is displayed for each specimen selected, as well as the scientific name, location and properties or age of the specimen. The fossils can be searched by area, age, and group; minerals by area, element, group, and property; and rocks by area, geological age, and type of rock. A series of questions allows users to identify their own specimens.

405

Earth Observations  

NASA Technical Reports Server (NTRS)

This document is concentrates on a couple of the missions where the Spacelab hardware was used to do Earth science. The Atmospheric Laboratory for Applications and Science (ATLAS) series of missions and the Lidar in-Space Technology Experiment (LITE) mission, the ATLAS being a series of three Shuttle missions that were very much Spacelab missions, are described. A little bit about the history, what the missions were, some of the instruments that were on them, and results are given.

Kaye, Jack

2000-01-01

406

Earth Rocks!  

NSDL National Science Digital Library

The purpose of this lesson is to introduce students to the basic elements of our Earth's crust: rocks, soils and minerals. They learn how we categorize rocks, soils and minerals and how they are literally the foundation for our civilization. Students also explore how engineers use rocks, soils and minerals to create the buildings, roads, vehicles, electronics, chemicals, and other objects we use to enhance our lives.

Integrated Teaching And Learning Program

407

Earth's Biomes  

NSDL National Science Digital Library

What are the characteristics of Earth's biomes? First, open the Biomes Graphic Organizer Now read through Information on Aquatic Biome (Freshwater) and fill in 5 characterestics of a freshwater biome in your graphic organizer. Now read through Information on Desert and fill in 5 characteristics of a desert biome in your graphic organizer. Now read through Information on Rainforest and fill in 5 characteristics of rainforest biome in your graphic organizer. Now ...

Ms. Allman

2012-04-05

408

Earth Observatory  

NSDL National Science Digital Library

This Web site includes shares the images, stories and discoveries that emerge from NASA Earth science research, including its satellite missions, in-the-field research and climate models. View global maps of NASA data, check out the Image of the Day and images of current events, and read feature articles and blogs. Also includes special collections of NASA images, including the World of Change series, which documents how our planetâs land, oceans, atmosphere and Sun are changing over time.

2011-01-01

409

Earth Day  

NSDL National Science Digital Library

Wow! Endagered species are everywhere! Just understanding the needs of animals will help them to survive longer. Find out how much your use of energy leaves a 'carbon' footprint on the earth. We all need to use our limited resources wisely. Reduce your footprint! Find out how and take the carbon footrpint quiz here. Carbon Footprint Watch the following YouTube video to hear a special message from Carl Hiaasen, the ...

Mrs. Datwyler

2010-04-19

410

Computer modelling of the reduction of rare earth dopants in barium aluminate  

SciTech Connect

Long lasting phosphorescence in barium aluminates can be achieved by doping with rare earth ions in divalent charge states. The rare earth ions are initially in a trivalent charge state, but are reduced to a divalent charge state before being doped into the material. In this paper, the reduction of trivalent rare earth ions in the BaAl{sub 2}O{sub 4} lattice is studied by computer simulation, with the energetics of the whole reduction and doping process being modelled by two methods, one based on single ion doping and one which allows dopant concentrations to be taken into account. A range of different reduction schemes are considered and the most energetically favourable schemes identified. - Graphical abstract: The doping and subsequent reduction of a rare earth ion into the barium aluminate lattice. Highlights: > The doping of barium aluminate with rare earth ions reduced in a range of atmospheres has been modelled. > The overall solution energy for the doping process for each ion in each reducing atmosphere is calculated using two methods. > The lowest energy reduction process is predicted and compared with experimental results.

Rezende, Marcos V. dos S; Valerio, Mario E.G. [Department of Physics, Federal University of Sergipe, 49100-000 Sao Cristovao, SE (Brazil); Jackson, Robert A., E-mail: r.a.jackson@chem.keele.ac.uk [School of Physical and Geographical Sciences, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom)

2011-08-15

411

Ferritin protein encapsulated photoluminescent rare earth nanoparticle  

NASA Astrophysics Data System (ADS)

Rare earth (yttrium (Y), europium (Eu), and terbium (Tb)) nanoparticles and Eu and Tb doped Y nanoparticles are synthesized in an apoferritin cavity. They exhibit a narrow size distribution and a high stability in an aqueous solution at pH 8.5. Eu and Eu doped Y (Y:Eu) nanoparticles exhibit red photoluminescence (emission peaks: 590 and 614 nm), while Tb and Tb doped Y (Y:Tb) nanoparticles exhibit green photoluminescence (emission peaks: 488, 544, 582, and 618 nm). High-resolution electron microscopy observations reveal that about 5% of the nanoparticles have a lattice structure, while the remaining nanoparticles are amorphous. Electron diffraction of the Y nanoparticles gives lattice spacings corresponding to the cubic structure of yttrium oxide (Y2O3). The most optimal dopant content for luminescence of Y:Eu and Y:Tb nanoparticles in apoferritin cavity are about 60% and 40%, respectively.

Harada, T.; Yoshimura, H.

2013-07-01

412

Impact Earth  

NSDL National Science Digital Library

This 24 minute planetarium show teaches about meteors, meteorites, asteroids, and comets. The show was created for fulldome theaters, but is also available on DVD to be shown in flat version for TVs and computer monitors, and can be freely viewed online. It shows the effects of the Chixulub and Tungusta events, plus the Pallasite impact that resulted in the Brenham meteorite fall, and describes ways that asteroid hunters seek new objects in the solar system, and how ground penetrating radar is used to find meteorites that have survived to the Earth's surface. Narrated by astronaut Tom Jones, it also discusses ways that humans might try to deflect an asteroid or comet that is on a collision course with Earth. The show was created for informal science venues (digital planetariums); it is also useful as supplemental material for middle school science. Impact Earth is available for free if presented directly from the Space Update site (widescreen or fisheye views linked from YouTube). Otherwise, a DVD of the show can be purchased for $10.

413

Near-infrared down-conversion in rare-earth-doped chloro-sulfide glass GeS{sub 2}-Ga{sub 2}S{sub 3}-CsCl: Er, Yb  

SciTech Connect

Chloro-sulfide glass with low phonon energy, GeS{sub 2}-Ga{sub 2}S{sub 3}-CsCl, is co-doped with Er and Yb. This active glass is a potential downconversion material for modifying the solar spectrum to improve the efficiency of solar cells. Two downconversion processes from visible to near infrared are observed. In the first process, an energy transfer between Er{sup 3+} ions and Yb{sup 3+} ions occurs. In that case, one photon is absorbed by the {sup 4}I{sub 15/2}{yields}{sup 2}H{sub 11/2} (Er{sup 3+}) transition and then two photons are emitted by {sup 2}F{sub 5/2}{yields}{sup 2}F{sub 7/2} (Yb{sup 3+}) and {sup 4}I{sub 13/2}{yields}{sup 4}I{sub 15/2} (Er{sup 3+}), respectively. In the second process, downconversion takes place from the charge-transfer state of Yb{sup 3+}-S{sup 2-} to the 4f states of Yb{sup 3+} ions, which leads to an intense excitation band between 400 nm and 600 nm, and an emission at 1000 nm. Quantum yields for downconversion are measured. The highest quantum yields of emission below 1200 nm and 1650 nm are equal to 51% and 76%, respectively.

Fan Bo; Point, Celine; Adam, Jean-Luc; Zhang Xianghua; Ma Hongli [Equipe Verres et Ceramiques, UMR CNRS 6226 Sciences Chimiques de Rennes, Universite de Rennes 1, Campus de Beaulieu, Rennes 35042 (France); Fan Xianping [Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

2011-12-01

414

NASA's Current Earth Science Program  

NASA Technical Reports Server (NTRS)

NASA's Earth science program is a scientific endeavor whose goal is to provide long-term understanding of the Earth as an integrated system of land, water, air and life. A highly developed scientific knowledge of the Earth system is necessary to understand how the environment affects humanity, and how humanity may be affecting the environment. The remote sensing technologies used to gather the global environmental data used in such research also have numerous practical applications. Current applications of remote sensing data demonstrate their practical benefits in areas such as the monitoring of crop conditions and yields, natural disasters and forest fires; hazardous waste clean up; and tracking of vector-borne diseases. The long-term availability of environmental data is essential for the continuity of important research and applications efforts. NASA's Earth observation program has undergone many changes in the recent past.

Charles, Leslie Bermann

1998-01-01

415

The Effects of Student Multiple Intelligence Preference on Integration of Earth Science Concepts and Knowledge within a Middle Grades Science Classroom.  

ERIC Educational Resources Information Center

This research was conducted in an eastern Tennessee 8th grade science classroom with 99 students participating. The action research project attempted to examine an adolescent science student's integration of science concepts within a project-based setting using the multiple intelligence theory. In an effort to address the national science…

Cutshall, Lisa Christine

416

Laser spectroscopy of rare earth ions  

Microsoft Academic Search

The main part of this thesis reports on the study of a wide range of EuVO4 samples grown from different starting flux materials, and doped with different rare earth ions. Conventional optical absorption and emission spectroscopy was used to measure the energies of the 5D and 7F levels of the Eu(3+) ion in the different growths. Related optical absorption work

Peter C. Hansen

1990-01-01

417

Earth's extensive entropy bound  

E-print Network

The possibility of planetary mass black hole production by crossing entropy limits is addressed. Such a possibility is given by pointing out that two geophysical quantities have comparable values: first, Earth's total negative entropy flux integrated over geological time and, second, its extensive entropy bound, which follows as a tighter bound to the Bekenstein limit when entropy is an extensive function. The similarity between both numbers suggests that the formation of black holes from planets may be possible through a strong fluctuation toward thermodynamic equilibrium which results in gravothermal instability and final collapse. Briefly discussed are implications for the astronomical observation of low mass black holes and for Fermi's paradox.

A. M. Lisewski

2007-10-18