Insights into thermal diffusion of germanium and oxygen atoms in HfO{sub 2}/GeO{sub 2}/Ge gate stacks and their suppressed reaction with atomically thin AlO{sub x} interlayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogawa, Shingo, E-mail: Shingo-Ogawa@trc.toray.co.jp; Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871; Asahara, Ryohei

2015-12-21

The thermal diffusion of germanium and oxygen atoms in HfO{sub 2}/GeO{sub 2}/Ge gate stacks was comprehensively evaluated by x-ray photoelectron spectroscopy and secondary ion mass spectrometry combined with an isotopic labeling technique. It was found that {sup 18}O-tracers composing the GeO{sub 2} underlayers diffuse within the HfO{sub 2} overlayers based on Fick's law with the low activation energy of about 0.5 eV. Although out-diffusion of the germanium atoms through HfO{sub 2} also proceeded at the low temperatures of around 200 °C, the diffusing germanium atoms preferentially segregated on the HfO{sub 2} surfaces, and the reaction was further enhanced at high temperatures withmore » the assistance of GeO desorption. A technique to insert atomically thin AlO{sub x} interlayers between the HfO{sub 2} and GeO{sub 2} layers was proven to effectively suppress both of these independent germanium and oxygen intermixing reactions in the gate stacks.« less

Synthesis and photoluminescence of ultra-pure germanium nanoparticles

NASA Astrophysics Data System (ADS)

Chivas, R.; Yerci, S.; Li, R.; Dal Negro, L.; Morse, T. F.

2011-09-01

We have used aerosol deposition to synthesize defect and micro-strain free, ultra-pure germanium nanoparticles. Transmission electron microscopy images show a core-shell configuration with highly crystalline core material. Powder X-ray diffraction measurements verify the presence of highly pure, nano-scale germanium with average crystallite size of 30 nm and micro-strain of 0.058%. X-ray photoelectron spectroscopy demonstrates that GeO x ( x ⩽ 2) shells cover the surfaces of the nanoparticles. Under optical excitation, these nanoparticles exhibit two separate emission bands at room temperature: a visible emission at 500 nm with 0.5-1 ns decay times and an intense near-infrared emission at 1575 nm with up to ˜20 μs lifetime.

One-Pot Synthesis of GeAs Ultrafine Particles from Coal Fly Ash by Vacuum Dynamic Flash Reduction and Inert Gas Condensation.

PubMed

Zhang, Lingen; Xu, Zhenming

2017-06-16

Ge-monopnictides (GeAs) plays critical role in high-tech industry, especially in the field of advanced optical devices and infrared. As a secondary material, coal fly ash could be further recycled to retrieve germanium and prepare GeAs material with high added values. Hence, the aim of this paper is to propose a one-pot synthesis that uses vacuum flash reduction and inert-gas consolidation method to prepare GeAs ultrafine particles. Germanium in coal fly ash can be successfully recycled; simultaneously, GeAs ultrafine particles were prepared. Separation principle and feasibility of this process was discussed. Temperature, carrier gas flow rate and system pressure were the major factors on formation, morphology and distribution of particle size of GeAs ultrafine particles. A three steps synthetic mechanism was clarified, namely, thermal rupture of coal fly ash and release of GeO 2 and As 2 O 3 , the gas-solid phase reaction of GeO 2 , As 2 O 3 and coke to generate metallic Ge and As in vacuum flash reduction. Meantime, GeAs were produced in the gas phase reaction. Finally, GeAs ultrafine particles were obtained by carrier gas condensation. In short, this research developed a practical and environment-friendly one-pot synthesis to recycle germanium in coal fly ash and prepare GeAs ultrafine particles with high added values.

[Effects of germanium on cell growth, polysaccharide production and cellular redox status in suspension cultures of protocorm-like bodies of Dendrobium huoshanense].

PubMed

Wei, Ming; Yang, Chaoying; Jiang, Shaotong

2010-03-01

To solve the problem of low growth rate and metabolism level in suspension cultures of protocorm-like bodies (PLBs) of Dendrobium huoshanense. The effects of germanium on PLB proliferation and accumulation of polysaccharides together with nutrient utilization were investigated and the contents of reducing sugars, soluble proteins, the activities of antioxidant enzymes and redox status of the cells of PLB were analyzed. The results indicated that the optimum concentration of germanium dioxide (4.0 mg/L) significantly enhanced the cell growth and accumulation of polysaccharides, greatly improved contents of reducing sugars and soluble proteins, increased the activities of superoxide dismutase (SOD) and catalase (CAT) but decreased the activity of peroxidase(POD). The cell dry weight and production of polysaccharides were 32.6 g/L and 3.78 g/L, respectively. The analysis of cellular redox status showed that the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) in cells and the activity of glutathione reductase were significantly increased by the addition of germanium dioxide. The suitable concentration of germanium dioxide was beneficial to the cell growth and the accumulation of polysaccharides.

Thermodynamics Behavior of Germanium During Equilibrium Reactions between FeOx-CaO-SiO2-MgO Slag and Molten Copper

NASA Astrophysics Data System (ADS)

Shuva, M. A. H.; Rhamdhani, M. A.; Brooks, G. A.; Masood, S.; Reuter, M. A.

2016-10-01

The distribution ratio of germanium (Ge), L_{{Ge}}^{s/m} during equilibrium reactions between magnesia-saturated FeOx-CaO-SiO2 (FCS) slag and molten copper has been measured under oxygen partial pressures from 10-10 to 10-7 atm and at temperatures 1473 to 1623 K (1200 to 1350 °C). It was observed that the Ge distribution ratio increases with increasing oxygen partial pressure, and with decreasing temperature. It was also observed that the distribution ratio is strongly dependent on slag basicity. The distribution ratio was observed to increase with increasing optical basicity. At fixed CaO concentration in the slag, the distribution ratio was found to increase with increasing Fe/SiO2 ratio, tending to a plateau at L_{{Ge}}^{s/m} = 0.8. This behavior is consistent with the assessment of ionic bond fraction carried out in this study, and suggested the acidic nature of germanium oxide (GeO2) in the slag system studied. The characterisation results of the quenched slag suggested that Ge is present in the FeOx-CaO-SiO2-MgO slag predominantly as GeO2. At 1573 K (1300 °C) and p_{{{{O}}2 }} = 10-8 atm, the activity coefficient of GeO2 in the slag was calculated to be in the range of 0.24 to 1.50. The results from the current study suggested that less-basic slag, high operating temperature, and low oxygen partial pressure promote a low Ge distribution ratio. These conditions are desired for maximizing Ge recovery, for example, during pyrometallurgical processing of Ge-containing e-waste through secondary copper smelting. Overall, the thermodynamics data generated from this study can be used for process modeling purposes for improving recovery of Ge in primary and secondary copper smelting processes.

Photochemical process of divalent germanium responsible for photorefractive index change in GeO2-SiO2 glasses.

PubMed

Sakoh, Akifumi; Takahashi, Masahide; Yoko, Toshinobu; Nishii, Junji; Nishiyama, Hiroaki; Miyamoto, Isamu

2003-10-20

The photoluminescence spectra of the divalent Ge (Ge2+) center in GeO2-SiO2 glasses with different photosensitivities were investigated by means of excitation-emission energy mapping. The ultraviolet light induced photorefractivity has been correlated with the local structure around the Ge2+ centers. The glasses with a larger photorefractivity tended to exhibit a greater band broadening of the singlet-singlet transition on the higher excitation energy side accompanied by an increase in the Stokes shifts. This strongly suggests the existence of highly photosensitive Ge2+ centers with higher excitation energies. It is also found that the introduction of a hydroxyl group or boron species in GeO2-SiO2 glasses under appropriate conditions modifies the local environment of Ge2+ leading to an enhanced photorefractivity.

Experimental and Theoretical Equation of State of GeO2 to 1.2 Mbars

NASA Astrophysics Data System (ADS)

Dutta, R.; White, C.; Greenberg, E.; Prakapenka, V. B.; Duffy, T. S.

2017-12-01

Germanium dioxide, GeO2, has been used widely as an analog in structural studies of crystalline, amorphous, and liquid SiO2 at high pressures (Micoulaut et al. 2006). Crystalline GeO2 follows a similar sequence of phase transitions as crystalline SiO2 but at substantially lower pressures making it useful as an analog for the behavior of silica in deep interiors of terrestrial and extra-solar planets. However, much of the existing work on GeO2 is fragmentary, and there is limited experimental data above 50 GPa. In this study, we report detailed equation of state (EOS) data for four phases (rutile, CaCl2, α-PbO2 and pyrite-type) of GeO2 using both laser-heated diamond anvil cell experiments and theoretical density functional theory (DFT) calculations. Experiments were conducted at sector 13 of the Advanced Photon Source. The rutile phase was synthesized from α-quartz starting material by laser heating at 4.7 GPa. The pressure-volume data for this phase can be fit using a 3rd order Birch-Murnaghan equation of state (EOS) with V0 = 55.33 Å3 (fixed), K0 = 225(10) GPa, K0' = 5(1), where V0, K0, K0' are the zero-pressure volume, bulk modulus and its pressure derivative respectively. In a separate run, the CaCl2-type phase was synthesized at 35.9 GPa and the sample remained in this structure up to 68.3 GPa. The EOS parameters in this case are V0 = 55.9 (1) Å3, K0 = 238 (4) GPa and K0' = 4 (fixed). The α-PbO2-type phase was examined between 51 and 90 GPa, yielding the following EOS parameters: V0 = 107.6 (2) Å3, K0 = 291 (5) GPa and K0' = 4 (fixed). The pyrite-type phase was then synthesized and examined up to the peak pressure of 119.5 GPa. The best fit to the data is obtained using V0 = 100.7 (1) Å3, K0 = 339 (4) GPa and K0' = 4 (fixed). These values will be compared with the results of theoretical calculations using different exchange correlation functionals. Our results will also be compared with shock wave data for GeO2 to better understand the behavior of this material under dynamic compression. In addition, detailed comparison between GeO2 crystals and glass as well as with SiO2 crystals and glass will provide insights into how structural changes and densification of germanate and silicate glasses at high pressure compare with the corresponding crystalline phases. ReferencesMicoulaut M, Cormier L, Henderson GS (2006) J Phys-Condens Matter 18: R753-R784.

Hydrothermal synthesis of bismuth germanium oxide

DOEpatents

Boyle, Timothy J.

2016-12-13

A method for the hydrothermal synthesis of bismuth germanium oxide comprises dissolving a bismuth precursor (e.g., bismuth nitrate pentahydrate) and a germanium precursor (e.g., germanium dioxide) in water and heating the aqueous solution to an elevated reaction temperature for a length of time sufficient to produce the eulytite phase of bismuth germanium oxide (E-BGO) with high yield. The E-BGO produced can be used as a scintillator material. For example, the air stability and radioluminescence response suggest that the E-BGO can be employed for medical applications.

Size-Tunable Photothermal Germanium Nanocrystals.

PubMed

Sun, Wei; Zhong, Grace; Kübel, Christian; Jelle, Abdinoor A; Qian, Chenxi; Wang, Lu; Ebrahimi, Manuchehr; Reyes, Laura M; Helmy, Amr S; Ozin, Geoffrey A

2017-05-22

Germanium nanocrystals (ncGe) have not received as much attention as silicon nanocrystals (ncSi). However, Ge has demonstrated superiority over Si nanomaterials in some applications. Examples include, high charge-discharge rate lithium-ion batteries, small band-gap opto-electronic devices, and photo-therapeutics. When stabilized in an oxide matrix (ncGe/GeO x ), its high charge-retention has enabled non-volatile memories. It has also found utility as a high-capacity anode material for Li-ion batteries with impressive stability. Herein, we report an organic-free synthesis of size-controlled ncGe in a GeO x matrix as well as freestanding ncGe, via the thermal disproportionation of GeO prepared from thermally induced dehydration of Ge(OH) 2 . The photothermal effect of ncGe, quantified by Raman spectroscopy, is found to be size dependent and superior to ncSi. This advance suggests applications of ncGe in photothermal therapy, desalination, and catalysis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Application of GeO2 nanoparticle as electrically erasable memory and its photo catalytic behaviour

NASA Astrophysics Data System (ADS)

Seal, M.; Bose, N.; Mukherjee, S.

2018-06-01

Germanium oxide nanoparticle is synthesized from bulk GeO2 powder through hydrothermal technique. The structural characterization of the prepared sample is performed with x-ray Diffraction and Transmission Electron Microscope. From the PL emission spectra and x-ray photoelectron spectra, the existence of oxygen defects inside the sample is confirmed. Thermogravimetric (TG) analysis of the sample shows that there is no weight loss with increase in temperature instead of a very little weight gain. An estimation of Oxygen vacancy concentration is made from the amount of weight gain as measured during TG analysis. The sample is also characterized with PE loop tracer, which indicates that GeO2 nanoparticle is able to show hysteresis loop regarding variation of Polarization with electric field. Such phenomenon implies that the sample can be used as electrically erasable memory device. Further, GeO2 nanoparticle is also exploited as photo catalyst to degrade Methylene Blue (MB) solution in the presence of ultraviolet ray. This phenomenon is also explained with oxygen vacancy.

Coordination complex pyrolyzation for the synthesis of nanostructured GeO₂ with high lithium storage properties.

PubMed

Li, Xiaona; Liang, Jianwen; Hou, Zhiguo; Zhu, Yongchun; Wang, Yan; Qian, Yitai

2014-11-21

A new (NH4)3H(Ge7O16)(H2O)2.72 precursor-pyrolyzation approach was designed and developed for the facile synthesis of nanostructured GeO2, avoiding the use of any hazardous or expensive germanium compounds. The products show promising anode application in lithium ion batteries with high capacity and excellent cycling stability.

Water soluble nano-scale transient material germanium oxide for zero toxic waste based environmentally benign nano-manufacturing

NASA Astrophysics Data System (ADS)

Almuslem, A. S.; Hanna, A. N.; Yapici, T.; Wehbe, N.; Diallo, E. M.; Kutbee, A. T.; Bahabry, R. R.; Hussain, M. M.

2017-02-01

In the recent past, with the advent of transient electronics for mostly implantable and secured electronic applications, the whole field effect transistor structure has been dissolved in a variety of chemicals. Here, we show simple water soluble nano-scale (sub-10 nm) germanium oxide (GeO2) as the dissolvable component to remove the functional structures of metal oxide semiconductor devices and then reuse the expensive germanium substrate again for functional device fabrication. This way, in addition to transiency, we also show an environmentally friendly manufacturing process for a complementary metal oxide semiconductor (CMOS) technology. Every year, trillions of complementary metal oxide semiconductor (CMOS) electronics are manufactured and billions are disposed, which extend the harmful impact to our environment. Therefore, this is a key study to show a pragmatic approach for water soluble high performance electronics for environmentally friendly manufacturing and bioresorbable electronic applications.

Pressure-induced coordination changes in alkali-germanate melts - An in situ spectroscopic investigation

NASA Technical Reports Server (NTRS)

Farber, Danial L.; Williams, Quentin

1992-01-01

The structure of liquid Na2Ge2O5-H2O, a silicate melt analog, has been studied with Raman spectroscopy to pressures of 2.2 gigapascals. Upon compression, a peak near more than 240 wavenumbers associated with octahedral GeO6 groups grows relative to a peak near 500 wavenumbers associated with tetrahedral GeO4 groups. This change corresponds to an increase in octahedral germanium in the liquid from near 0 percent at ambient pressures to more than 50 percent at a pressure of 2.2 gigapascals. Silicate liquids pausibly undergo similar coordination changes at depth in the earth. Such structural changes may generate decreases in the fusion slopes of silicates at high pressures as well as neutrally buoyant magmas within the transition zone of the earth's mantle.

[Studies on the role of silicic acid in the development of higher plants].

PubMed

Werner, D

1967-03-01

Germanium acid, a specific inhibitor of the silicic acid metabolism in diatoms, inhibits the growth of Sinapis alba, Lemna minor, Wolffia arrhiza, Nicotiana tabacum, Tradescantia spec, Zinnia elegans, and Secale cereale when applied in the same concentrations as those used in the case of diatoms (15-75 μg GeO2/ml medium). The growth of Aspergillus niger, Phycomyces blakesleanus, Escherichia coli K 12, Euglena gracilis and Pandorina morum is not influenced by these and higher concentrations of Germanium acid. By application of high concentrations of silicic acid, the growth inhibition produced by germanium acid in Lemna minor is partially reduced. Plants of Lemna minor which have been inhibited by germanium acid are essentially smaller than plants grown in a normal medium; their chlorophyll content is significantly decreased. The growth of the roots in Lemna is particularly inhibited. Isolated growing roots of Lycopersicon pimpinellifolium MILL. are inhibited by small concentrations of Ge(OH)4 (ca. 1,5×10(-4) M/l). In contrast to the growth of older plants, the germination of Secale cereale and Sinapis alba is not influenced by Ge(OH)4. The effects of germanium acid are discussed in relation to the physiological role of silicic acid. The results suggest that the element silicon, in the form of silicic acid, is generally essential for the normal development of higher plants.

Preparation of special purity Ge - S - I and Ge - Se - I glasses

NASA Astrophysics Data System (ADS)

Velmuzhov, A. P.; Sukhanov, M. V.; Shiryaev, V. S.; Kotereva, T. V.; Snopatin, G. E.; Churbanov, M. F.

2017-05-01

The paper considers the new approaches for the production of special pure Ge - S - I and Ge - Se - I glasses via the germanium(IV) iodide, germanium(II) sulfide, as well as the Ge2S3, Ge2S3I2 and Ge2Se3I2 glassy alloys. The glass samples containing 0.03-0.17 ppm(wt) hydrogen impurity in the form of SH-group, 0.04-0.15 ppm(wt) hydrogen impurity in the form of SeH-group, and 0.5-7.8 ppm(wt) oxygen impurity in the form of Ge-O were produced. Using a crucible technique, the single-index [GeSe4]95I5 glass fibers of 300-400 μm diameter were drawn. The minimum optical losses in the best fiber were 1.7 dB/m at a wavelength of 5.5 μm; the background optical losses were within 2-3 dB/m in the spectral range of 2.5-8 μm.

Method for carbon dioxide sequestration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yifeng; Bryan, Charles R.; Dewers, Thomas

A method for geo-sequestration of a carbon dioxide includes selection of a target water-laden geological formation with low-permeability interbeds, providing an injection well into the formation and injecting supercritical carbon dioxide (SC-CO.sub.2) and water or bine into the injection well under conditions of temperature, pressure and density selected to cause the fluid to enter the formation and splinter and/or form immobilized ganglia within the formation.

Airborne mapping of Seoul's atmosphere: Trace gas measurements from GeoTASO during KORUS-AQ

NASA Astrophysics Data System (ADS)

Nowlan, C. R.; Al-Saadi, J. A.; Castellanos, P.; Chance, K.; Gonzalez Abad, G.; Janz, S. J.; Judd, L.; Kowalewski, M. G.; Liu, X.

2017-12-01

The Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) instrument is a pushbroom airborne remote sensing instrument capable of making measurements of air quality and ocean color using backscattered UV and visible light. GeoTASO is an airborne test-bed for the upcoming Tropospheric Emissions: Monitoring of Pollution (TEMPO) and Geostationary Environment Monitoring Spectrometer (GEMS) geostationary satellite missions, which will measure air quality over North America and Asia, respectively. GeoTASO also acts as a satellite analogue during field campaigns. GeoTASO flew on the NASA Langley Research Center UC-12 aircraft during the Korea-United States Air Quality Study in May-June 2016, collecting spectra over South Korea during 30 flights over 19 flight days. These observations can be used to derive 2-D maps of tropospheric trace gases including ozone, nitrogen dioxide, sulfur dioxide, formaldehyde, nitrous acid and glyoxal below the aircraft at spatial resolutions between 250 m x 250 m and 1 km x 1 km, depending on the gas. We present spatially resolved trace gas retrievals over Seoul and its surrounding industrial regions, and comparisons with correlative satellite and campaign data.

Genetic algorithm prediction of two-dimensional group-IV dioxides for dielectrics

NASA Astrophysics Data System (ADS)

Singh, Arunima K.; Revard, Benjamin C.; Ramanathan, Rohit; Ashton, Michael; Tavazza, Francesca; Hennig, Richard G.

2017-04-01

Two-dimensional (2D) materials present a new class of materials whose structures and properties can differ from their bulk counterparts. We perform a genetic algorithm structure search using density-functional theory to identify low-energy structures of 2D group-IV dioxides A O2 (A =Si , Ge, Sn, Pb). We find that 2D SiO2 is most stable in the experimentally determined bi-tetrahedral structure, while 2D SnO2 and PbO2 are most stable in the 1 T structure. For 2D GeO2, the genetic algorithm finds a new low-energy 2D structure with monoclinic symmetry. Each system exhibits 2D structures with formation energies ranging from 26 to 151 meV/atom, below those of certain already synthesized 2D materials. The phonon spectra confirm their dynamic stability. Using the HSE06 hybrid functional, we determine that the 2D dioxides are insulators or semiconductors, with a direct band gap of 7.2 eV at Γ for 2D SiO2, and indirect band gaps of 4.8-2.7 eV for the other dioxides. To guide future applications of these 2D materials in nanoelectronic devices, we determine their band-edge alignment with graphene, phosphorene, and single-layer BN and MoS2. An assessment of the dielectric properties and electrochemical stability of the 2D group-IV dioxides shows that 2D GeO2 and SnO2 are particularly promising candidates for gate oxides and 2D SnO2 also as a protective layer in heterostructure nanoelectronic devices.

Trace Gas Measurements from the GeoTASO and GCAS Airborne Instruments: An Instrument and Algorithm Test-Bed for Air Quality Observations from Geostationary Orbit

NASA Astrophysics Data System (ADS)

Nowlan, C. R.; Liu, X.; Janz, S. J.; Leitch, J. W.; Al-Saadi, J. A.; Chance, K.; Cole, J.; Delker, T.; Follette-Cook, M. B.; Gonzalez Abad, G.; Good, W. S.; Kowalewski, M. G.; Loughner, C.; Pickering, K. E.; Ruppert, L.; Soo, D.; Szykman, J.; Valin, L.; Zoogman, P.

2016-12-01

The Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) and the GEO-CAPE Airborne Simulator (GCAS) instruments are pushbroom sensors capable of making remote sensing measurements of air quality and ocean color. Originally developed as test-bed instruments for the Geostationary Coastal and Air Pollution Events (GEO-CAPE) decadal survey, these instruments are now also part of risk reduction for the upcoming Tropospheric Emissions: Monitoring of Pollution (TEMPO) and Geostationary Environment Monitoring Spectrometer (GEMS) geostationary satellite missions, and will provide validation capabilities after the satellite instruments are in orbit. GeoTASO and GCAS flew on two different aircraft in their first intensive air quality field campaigns during the DISCOVER-AQ missions over Texas in 2013 and Colorado in 2014. GeoTASO was also deployed in 2016 during the KORUS-AQ field campaign to make measurements of trace gases and aerosols over Korea. GeoTASO and GCAS collect spectra of backscattered solar radiation in the UV and visible that can be used to derive 2-D maps of trace gas columns below the aircraft at spatial resolutions on the order of 250 x 500 m. We present spatially resolved maps of trace gas retrievals of ozone, nitrogen dioxide, formaldehyde and sulfur dioxide over urban areas and power plants from flights during the field campaigns, and comparisons with data from ground-based spectrometers, in situ monitoring instruments, and satellites.

Structural and thermodynamic consideration of metal oxide doped GeO{sub 2} for gate stack formation on germanium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Cimang, E-mail: cimang@adam.t.u-tokyo.ac.jp; Lee, Choong Hyun; Zhang, Wenfeng

2014-11-07

A systematic investigation was carried out on the material and electrical properties of metal oxide doped germanium dioxide (M-GeO{sub 2}) on Ge. We propose two criteria on the selection of desirable M-GeO{sub 2} for gate stack formation on Ge. First, metal oxides with larger cation radii show stronger ability in modifying GeO{sub 2} network, benefiting the thermal stability and water resistance in M-GeO{sub 2}/Ge stacks. Second, metal oxides with a positive Gibbs free energy for germanidation are required for good interface properties of M-GeO{sub 2}/Ge stacks in terms of preventing the Ge-M metallic bond formation. Aggressive equivalent oxide thickness scalingmore » to 0.5 nm is also demonstrated based on these understandings.« less

Correlation between Optical Properties and Chemical Composition of Sputter-Deposited Germanium Oxide (GEOX) Films (Postprint)

DTIC Science & Technology

2014-03-18

the GeOx films. The measured index of refraction ( n ) at a wavelength (k) of 550 nm is 4.67 for films grown without any oxygen, indicating behavior...in n (k = 550 nm) to 2.62 and occurs at Γ = 0.25. Finally n drops to 1.60 for U = 0.50–1.00, where the films become GeO2. A detailed correlation...between Γ n , k and stoichiometry in DC sputtered GeOx films is presented and discussed. 15. SUBJECT TERMS ellipsometry, reactive sputtering, x-ray

Trace Gas Retrievals from the GeoTASO Aircraft Instrument

NASA Astrophysics Data System (ADS)

Nowlan, C. R.; Liu, X.; Leitch, J. W.; Liu, C.; Gonzalez Abad, G.; Chance, K.; Cole, J.; Delker, T.; Good, W. S.; Murcray, F.; Ruppert, L.; Soo, D.; Loughner, C.; Follette-Cook, M. B.; Janz, S. J.; Kowalewski, M. G.; Pickering, K. E.; Zoogman, P.; Al-Saadi, J. A.

2015-12-01

The Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) instrument is a passive remote sensing instrument capable of making 2-D measurements of trace gases and aerosols from aircraft. The instrument measures backscattered UV and visible radiation, allowing the retrieval of trace gas amounts below the aircraft at horizontal resolutions on the order of 250 m x 250 m. GeoTASO was originally developed under NASA's Instrument Incubator Program as a test-bed instrument for the Geostationary Coastal and Air Pollution Events (GEO-CAPE) decadal survey mission, and is now also part of risk reduction for the upcoming Tropospheric Emissions: Monitoring of Pollution (TEMPO) and Geostationary Environment Monitoring Spectrometer (GEMS) geostationary satellite missions. We present spatially resolved observations of ozone, nitrogen dioxide, formaldehyde and sulfur dioxide over urban areas and power plants from flights during the DISCOVER-AQ field campaigns in Texas and Colorado, as well as comparisons with observations made by ground-based Pandora spectrometers, in situ monitoring instruments and other aircraft instruments deployed during these campaigns. These measurements at various times of day are providing a very useful data set for testing and improving TEMPO and GEMS retrieval algorithms, as well as demonstrating prototype validation strategies.

Nitrogen dioxide observations from the Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) airborne instrument: Retrieval algorithm and measurements during DISCOVER-AQ Texas 2013

EPA Science Inventory

The Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) airborne instrument is a test bed for upcoming air quality satellite instruments that will measure backscattered ultraviolet, visible and near-infrared light from geostationary orbit. GeoTASO flew on the NASA F...

GaN High Power Electronics

DTIC Science & Technology

2011-02-01

ARL) does not yet match the best work being done in Japan, the reasons for this have been identified as the relatively large carbon background...hand, SiC is a compound with a fixed composition. Second phases are formed, as opposed to solid solutions, when the group IV elements, carbon (C...Si, or germanium (Ge), are added to it. In order to form a 2DEG, a dielectric, usually silicon dioxide (SiO2), has to be grown or deposited on the

Kinetics of plasma oxidation of germanium-tin (GeSn)

NASA Astrophysics Data System (ADS)

Wang, Wei; Lei, Dian; Dong, Yuan; Zhang, Zheng; Pan, Jisheng; Gong, Xiao; Tok, Eng-Soon; Yeo, Yee-Chia

2017-12-01

The kinetics of plasma oxidation of GeSn at low temperature is investigated. The oxidation process is described by a power-law model where the oxidation rate decreases rapidly from the initial oxidation rate with increasing time. The oxidation rate of GeSn is higher than that of pure Ge, which can be explained by the higher chemical reaction rate at the GeSn-oxide/GeSn interface. In addition, the Sn atoms at the interface region exchange positions with the underlying Ge atoms during oxidation, leading to a SnO2-rich oxide near the interface. The bandgap of GeSn oxide is extracted to be 5.1 ± 0.2 eV by XPS, and the valence band offset at the GeSn-oxide/GeSn heterojunction is found to be 3.7 ± 0.2 eV. Controlled annealing experiments demonstrate that the GeSn oxide is stable with respect to annealing temperatures up to 400 °C. However, after annealing at 450 °C, the GeO2 is converted to GeO, and desorbs from the GeSn-oxide/GeSn, leaving behind Sn oxide.

Evaluation of GEOS-5 Sulfur Dioxide Simulations During the Frostburg, MD 2010 Field Campaign.

NASA Technical Reports Server (NTRS)

Buchard, V.; Da Silva, A. M.; Colarco, P.; Krotkov, N.; Dickerson, R. R.; Stehr, J. W.; Mount, G.; Spenei, E.; Arkinson, H. L.; He, H.

2013-01-01

Sulfur dioxide (SO2) is a major atmospheric pollutant with a strong anthropogenic component mostly produced by the combustion of fossil fuel and other industrial activities. As a precursor of sulfate aerosols that affect climate, air quality, and human health, this gas needs to be monitored on a global scale. Global climate and chemistry models including aerosol processes along with their radiative effects are important tools for climate and air quality research. Validation of these models against in-situ and satellite measurements is essential to ascertain the credibility of these models and to guide model improvements. In this study the Goddard Chemistry, Aerosol, Radiation, and Transport (GOCART) module running on-line inside the Goddard Earth Observing System version 5 (GEOS-5) model is used to simulate aerosol and SO2 concentrations. Data taken in November 2010 over Frostburg, Maryland during an SO2 field campaign involving ground instrumentation and aircraft are used to evaluate GEOS-5 simulated SO2 concentrations. Preliminary data analysis indicated the model overestimated surface SO2 concentration, which motivated the examination of mixing processes in the model and the specification of SO2 anthropogenic emission rates. As a result of this analysis, a revision of anthropogenic emission inventories in GEOS-5 was implemented, and the vertical placement of SO2 sources was updated. Results show that these revisions improve the model agreement with observations locally and in regions outside the area of this field campaign. In particular, we use the ground-based measurements collected by the United States Environmental Protection Agency (US EPA) for the year 2010 to evaluate the revised model simulations over North America.

Forward Modeling of Atmospheric Carbon Dioxide in GEOS-5: Uncertainties Related to Surface Fluxes and Sub-Grid Transport

NASA Technical Reports Server (NTRS)

Pawson, Steven; Ott, Lesley E.; Zhu, Zhengxin; Bowman, Kevin; Brix, Holger; Collatz, G. James; Dutkiewicz, Stephanie; Fisher, Joshua B.; Gregg, Watson W.; Hill, Chris;

Nitrogen Dioxide Observations from the Geostationary Trace Gas and Aerosol Sensor Optimization (GeoTaso) Airborne Instrument: Retrieval Algorithm and Measurements During DISCOVER-AQ Texas 2013

NASA Technical Reports Server (NTRS)

Nowlan, Caroline R.; Liu, Xiong; Leitch, James W.; Chance, Kelly; Abad, Gonzalo Gonzalez; Liu, Xiaojun; Zoogman, Peter; Cole, Joshua; Delker, Thomas; Good, William;

Shallow V-Shape Nanostructured Pit Arrays in Germanium Using Aqua Regia Electroless Chemical Etching

PubMed Central

Chaabane, Ibtihel; Banerjee, Debika; Touayar, Oualid; Cloutier, Sylvain G.

2017-01-01

Due to its high refractive index, reflectance is often a problem when using Germanium for optoelectronic devices integration. In this work, we propose an effective and low-cost nano-texturing method for considerably reducing the reflectance of bulk Germanium. To do so, uniform V-shape pit arrays are produced by wet electroless chemical etching in a 3:1 volume ratio of highly-concentrated hydrochloridric and nitric acids or so-called aqua regia bath using immersion times ranging from 5 to 60 min. The resulting pit morphology, the crystalline structure of the surface and the changes in surface chemistry after nano-patterning are all investigated. Finally, broadband near-infrared reflectance measurements confirm a significant reduction using this simple wet etching protocol, while maintaining a crystalline, dioxide-free, and hydrogen-passivated surface. It is important to mention that reflectance could be further reduced using deeper pits. However, most optoelectronic applications such as photodetectors and solar cells require relatively shallow patterning of the Germanium to allow formation of a pn-junction close to the surface. PMID:28773215

One-step Ge/Si epitaxial growth.

PubMed

Wu, Hung-Chi; Lin, Bi-Hsuan; Chen, Huang-Chin; Chen, Po-Chin; Sheu, Hwo-Shuenn; Lin, I-Nan; Chiu, Hsin-Tien; Lee, Chi-Young

2011-07-01

Fabricating a low-cost virtual germanium (Ge) template by epitaxial growth of Ge films on silicon wafer with a Ge(x)Si(1-x) (0 < x < 1) graded buffer layer was demonstrated through a facile chemical vapor deposition method in one step by decomposing a hazardousless GeO(2) powder under hydrogen atmosphere without ultra-high vacuum condition and then depositing in a low-temperature region. X-ray diffraction analysis shows that the Ge film with an epitaxial relationship is along the in-plane direction of Si. The successful growth of epitaxial Ge films on Si substrate demonstrates the feasibility of integrating various functional devices on the Ge/Si substrates.

Optical Jitter Effects on Target Detection and Tracking of Overhead Persistent Infrared Systems

DTIC Science & Technology

2015-12-01

infrared CdSe cadmium selenide DSP Defense Support Program FIR far-infrared FPA focal plane array Ge germanium GEO geostationary earth orbit...HBCRT High Energy Laser Beam Control Research Testbed HEL high energy laser HgCdTe mercury cadmium telluride IR infrared InSb indium antimonide...MOD model MTF modulation transfer function MWIR mid-wave infrared NIR near infrared OPIR overhead persistent infrared PbSe lead selenide

Nitrogen dioxide observations from the Geostationary Trace ...

EPA Pesticide Factsheets

The Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) airborne instrument is a test bed for upcoming air quality satellite instruments that will measure backscattered ultraviolet, visible and near-infrared light from geostationary orbit. GeoTASO flew on the NASA Falcon aircraft in its first intensive field measurement campaign during the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) Earth Venture Mission over Houston, Texas, in September 2013. Measurements of backscattered solar radiation between 420 and 465 nm collected on 4 days during the campaign are used to determine slant column amounts of NO2 at 250 m  ×  250 m spatial resolution with a fitting precision of 2.2 × 1015 moleculescm−2. These slant columns are converted to tropospheric NO2 vertical columns using a radiative transfer model and trace gas profiles from the Community Multiscale Air Quality (CMAQ) model. Total column NO2 from GeoTASO is well correlated with ground-based Pandora observations (r = 0.90 on the most polluted and cloud-free day of measurements and r = 0.74 overall), with GeoTASO NO2 slightly higher for the most polluted observations. Surface NO2 mixing ratios inferred from GeoTASO using the CMAQ model show good correlation with NO2 measured in situ at the surface during the campaign (r = 0.85). NO2 slant columns from GeoTASO also agree well with prelim

PCA-based SO2, NO2, and HCHO retrievals from GeoTASO airborne measurements during KORUS-AQ 2016 campaign

NASA Astrophysics Data System (ADS)

Chong, H.; Lee, S.; Jeong, U.; Kim, J.; Li, C.; Krotkov, N. A.; Al-Saadi, J. A.; Janz, S. J.; Kowalewski, M. G.; Nowlan, C. R.; Kang, M.; Joiner, J.; Haffner, D. P.; Koo, J. H.; Hong, H.; Lee, H.

2017-12-01

The Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) is an airborne instrument measuring backscattered radiance with a spectrometer covering the spectral range between 290-695 nm. GeoTASO flew on the B-200 (UC-12B) - LARC aircraft during the KORUS-AQ campaign, of which the spatial resolution is about 250 nm x 250 m. Principal component analysis (PCA) technique is used to retrieve slant column densities (SCD) of sulfur dioxide (SO2), nitrogen dioxide (NO2), and formaldehyde (HCHO). The fitting windows of SO2, NO2, and HCHO are 310-325 nm, 350-380 nm, and 335-357 nm respectively. The clear PCs of each species are collected from rural areas where are found to have less SCDs of each species from prior iteration step. Using the clear sector PCs and the cross section of each species, SCDs of each trace gas are obtained using the multiple linear regression method. Air mass factors (AMF) of each species are obtained using the atmospheric profiles from chemical transport model calculations during the campaign to convert SCDs to vertical column densities (VCD). The retrieved VCDs of each species well capture small point sources on the flight paths and their plumes propagating downwind areas, which was not available from the ground-based in-situ measurements. The retrieved VCDs will be compared and/or validated against other benchmark measurements during the campaign.

Evaluation of Sulfur Dioxide (SO2) Simulations with the GEOS-5/ GOCART Model during the Frostburg/DISCOVER-AQ Field Campaigns

NASA Astrophysics Data System (ADS)

Buchard-Marchant, V.; da Silva, A.; Colarco, P. R.; Krotkov, N. A.; Dickerson, R. R.; Stehr, J. W.; Spinei, E.; Mount, G. H.; Krask, D.

2011-12-01

Sulfur dioxide (SO2) is a major atmospheric pollutant, with a strong anthropogenic component mostly produced by the combustion of fossil fuel and other industrial activities. As a precursor of sulfate aerosols that affect climate, air quality and human health, this gas needs to be monitored on a global scale. Global climate and chemistry models including aerosol processes along with their radiative effects are important tools for climate and air quality research. Validation of these models against in-situ and satellite measurements are essential to ascertain the credibility of these models and to guide model improvements. In this study the Goddard Chemistry, Aerosol, Radiation, and Transport (GOCART) module running on-line inside the Goddard Earth Observing System version 5 (GEOS-5) model is used to simulate aerosol and SO2 concentrations. The global GEOS-5 system runs at a nominal 25 km horizontal resolution with 72 vertical levels; a comprehensive atmospheric data assimilation system is used to constrain the meteorological state of the model. Data taken over Maryland in the UM's Frostburg (November 2010) and NASA DISCOVER-AQ (July 2011) field campaigns are used to evaluate the GEOS-5 SO2 concentrations. In this presentation we show comparisons of simulated and measured SO2 concentration, using airborne and ground-based data sets, as well as data from the space-based OMI instrument. Preliminary data analysis indicated the model's overestimation of SO2 concentration at the surface, leading to a close examination of mixing processes in the model and the specification of SO2 anthropogenic emission rates. As a result of this analysis, we have implemented a revision of anthropogenic emission inventories in GEOS-5, and updated the vertical placement of SO2 sources. In this presentation we show how these revisions improve the model agreement with observations not only locally but also in regions outside the area of these field campaigns. In particular, we use the ground-based measurements from the Environmental Protection Agency (EPA) for the year 2010 to evaluate the revised model simulations over North America.

High-Resolution Electron Energy Loss Studies of Oxygen, Hydrogen, Nitrogen, Nitric Oxide, and Nitrous Oxide Adsorption on Germanium Surfaces.

NASA Astrophysics Data System (ADS)

Entringer, Anthony G.

The first high resolution electron energy loss spectroscopy (HREELS) studies of the oxidation and nitridation of germanium surfaces are reported. Both single crystal Ge(111) and disordered surfaces were studied. Surfaces were exposed to H, O_2, NO, N _2O, and N, after cleaning in ultra-high vacuum. The Ge surfaces were found to be non-reactive to molecular hydrogen (H_2) at room temperature. Exposure to atomic hydrogen (H) resulted hydrogen adsorption as demonstrated by the presence of Ge-H vibrational modes. The HREEL spectrum of the native oxide of Ge characteristic of nu -GeO_2 was obtained by heating the oxide to 200^circC. Three peaks were observed at 33, 62, and 106 meV for molecular oxygen (O_2) adsorbed on clean Ge(111) at room temperature. These peaks are indicative of dissociative bonding and a dominant Ge-O-Ge bridge structure. Subsequent hydrogen exposure resulted in a shift of the Ge-H stretch from its isolated value of 247 meV to 267 meV, indicative of a dominant +3 oxidation state. A high density of dangling bonds and defects and deeper oxygen penetration at the amorphous Ge surface result in a dilute bridge structure with a predominant +1 oxidation state for similar exposures. Molecules of N_2O decompose at the surfaces to desorbed N_2 molecules and chemisorbed oxygen atoms. In contrast, both oxygen and nitrogen are detected at the surfaces following exposure to NO molecules. Both NO and N_2O appear to dissociate and bond at the top surface layer. Molecular nitrogen (N_2) does not react with the Ge surfaces, however, a precursor Ge nitride is observed at room temperature following exposure to nitrogen atoms and ions. Removal of oxygen by heating of the NO-exposed surface to 550^circC enabled the identification of the Ge-N vibrational modes. These modes show a structure similar to that of germanium nitride. This spectrum is also identical to that of the N-exposed surface heated to 550^circC. Surface phonon modes of the narrow-gap semiconducting compounds Mg _2Sn, Mg_2Ge and Mg _2Si were detected at 29, 32, and 40 meV, respectively. The native oxide of all three show a dominant Mg-O mode at 80 meV. Probable Sn-O, Ge-O, and Si-O modes are also identified. Complete removal of the oxide layer was accomplished only on the Mg_2 Si surface but resulted in no noticeable change in the energy of the surface phonon. Results are compared to the known bulk optical properties of these compounds.

Method for carbon dioxide sequestration

DOEpatents

Wang, Yifeng; Bryan, Charles R.; Dewers, Thomas; Heath, Jason E.

2015-09-22

A method for geo-sequestration of a carbon dioxide includes selection of a target water-laden geological formation with low-permeability interbeds, providing an injection well into the formation and injecting supercritical carbon dioxide (SC--CO.sub.2) into the injection well under conditions of temperature, pressure and density selected to cause the fluid to enter the formation and splinter and/or form immobilized ganglia within the formation. This process allows for the immobilization of the injected SC--CO.sub.2 for very long times. The dispersal of scCO2 into small ganglia is accomplished by alternating injection of SC--CO.sub.2 and water. The injection rate is required to be high enough to ensure the SC--CO.sub.2 at the advancing front to be broken into pieces and small enough for immobilization through viscous instability.

Ge nanocrystals formed by furnace annealing of Ge(x)[SiO2](1-x) films: structure and optical properties

NASA Astrophysics Data System (ADS)

Volodin, V. A.; Cherkov, A. G.; Antonenko, A. Kh; Stoffel, M.; Rinnert, H.; Vergnat, M.

2017-07-01

Ge(x)[SiO2](1-x) (0.1  ⩽  x  ⩽  0.4) films were deposited onto Si(0 0 1) or fused quartz substrates using co-evaporation of both Ge and SiO2 in high vacuum. Germanium nanocrystals were synthesized in the SiO2 matrix by furnace annealing of Ge x [SiO2](1-x) films with x  ⩾  0.2. According to electron microscopy and Raman spectroscopy data, the average size of the nanocrystals depends weakly on the annealing temperature (700, 800, or 900 °C) and on the Ge concentration in the films. Neither amorphous Ge clusters nor Ge nanocrystals were observed in as-deposited and annealed Ge0.1[SiO2]0.9 films. Infrared absorption spectroscopy measurements show that the studied films do not contain a noticeable amount of GeO x clusters. After annealing at 900 °C intermixing of germanium and silicon atoms was still negligible thus preventing the formation of GeSi nanocrystals. For annealed samples, we report the observation of infrared photoluminescence at low temperatures, which can be explained by exciton recombination in Ge nanocrystals. Moreover, we report strong photoluminescence in the visible range at room temperature, which is certainly due to Ge-related defect-induced radiative transitions.

Nitrogen dioxide observations from the Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) airborne instrument: Retrieval algorithm and measurements during DISCOVER-AQ Texas 2013

NASA Astrophysics Data System (ADS)

Nowlan, Caroline R.; Liu, Xiong; Leitch, James W.; Chance, Kelly; González Abad, Gonzalo; Liu, Cheng; Zoogman, Peter; Cole, Joshua; Delker, Thomas; Good, William; Murcray, Frank; Ruppert, Lyle; Soo, Daniel; Follette-Cook, Melanie B.; Janz, Scott J.; Kowalewski, Matthew G.; Loughner, Christopher P.; Pickering, Kenneth E.; Herman, Jay R.; Beaver, Melinda R.; Long, Russell W.; Szykman, James J.; Judd, Laura M.; Kelley, Paul; Luke, Winston T.; Ren, Xinrong; Al-Saadi, Jassim A.

2016-06-01

The Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) airborne instrument is a test bed for upcoming air quality satellite instruments that will measure backscattered ultraviolet, visible and near-infrared light from geostationary orbit. GeoTASO flew on the NASA Falcon aircraft in its first intensive field measurement campaign during the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) Earth Venture Mission over Houston, Texas, in September 2013. Measurements of backscattered solar radiation between 420 and 465 nm collected on 4 days during the campaign are used to determine slant column amounts of NO2 at 250 m × 250 m spatial resolution with a fitting precision of 2.2 × 1015 moleculescm-2. These slant columns are converted to tropospheric NO2 vertical columns using a radiative transfer model and trace gas profiles from the Community Multiscale Air Quality (CMAQ) model. Total column NO2 from GeoTASO is well correlated with ground-based Pandora observations (r = 0.90 on the most polluted and cloud-free day of measurements and r = 0.74 overall), with GeoTASO NO2 slightly higher for the most polluted observations. Surface NO2 mixing ratios inferred from GeoTASO using the CMAQ model show good correlation with NO2 measured in situ at the surface during the campaign (r = 0.85). NO2 slant columns from GeoTASO also agree well with preliminary retrievals from the GEO-CAPE Airborne Simulator (GCAS) which flew on the NASA King Air B200 (r = 0.81, slope = 0.91). Enhanced NO2 is resolvable over areas of traffic NOx emissions and near individual petrochemical facilities.

Arsenic transformation and adsorption by iron hydroxide/manganese dioxide doped straw activated carbon

NASA Astrophysics Data System (ADS)

Xiong, Ying; Tong, Qiang; Shan, Weijun; Xing, Zhiqiang; Wang, Yuejiao; Wen, Siqi; Lou, Zhenning

2017-09-01

Iron hydroxide/manganese dioxide doped straw activated carbon was synthesized for As(III) adsorption. The Fe-Mn-SAc adsorbent has two advantages, on the one hand, the straw active carbon has a large surface area (1360.99 m2 g-1) for FeOOH and MnO2 deposition, on the other hand, the manganese dioxide has oxidative property as a redox potential of (MnO2 + H+)/Mn2+, which could convert As(III) into As(V). Combined with the arsenic species after reacting with Fe-Mn-SAc, the As(III) transformation and adsorption mechanism was discussed. H2AsO4-oxidized from As(III) reacts with the Fe-Mn-SAc by electrostatic interaction, and unoxidized As(III) as H3AsO3 reacts with SAc and/or iron oxide surface by chelation effect. The adsorption was well-described by Langmuir isotherms model, and the adsorption capacity of As(III) was 75.82 mg g-1 at pH 3. Therefore, considering the straw as waste biomass material, the biosorbent (Fe-Mn-SAc) is promising to be exploited for applications in the treatment of industrial wastewaters containing a certain ratio of arsenic and germanium.

An 8-year, high-resolution reanalysis of atmospheric carbon dioxide mixing ratios based on OCO-2 and GOSAT-ACOS retrievals

NASA Astrophysics Data System (ADS)

Weir, B.; Chatterjee, A.; Ott, L. E.; Pawson, S.

2017-12-01

This talk presents an overview of results from the GEOS-Carb reanalysis of retrievals of average-column carbon dioxide (XCO2) from the Orbiting Carbon Observatory 2 (OCO-2) and Greenhouse Gases Observing Satellite (GOSAT) satellite missions. The reanalysis is a Level 3 (L3) product: a collection of 3D fields of carbon dioxide (CO2) mixing ratios every 6 hours beginning in April 2009 going until the present on a grid with a 0.5 degree horizontal resolution and 72 vertical levels from the surface to 0.01 hPa. Using an assimilation methodology based on the Goddard Earth Observing System (GEOS) atmospheric data assimilation system (ADAS), the L3 fields are weighted averages of the two satellite retrievals and predictions from the GEOS general circulation model driven by assimilated meteorology from the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2). In places and times where there are a dense number of soundings, the observations dominate the predicted mixing ratios, while the model is used to fill in locations with fewer soundings, e.g., high latitudes and the Amazon. Blending the satellite observations with model predictions has at least two notable benefits. First, it provides a bridge for evaluating the satellite retrievals and their uncertainties against a heterogeneous collection of observations including those from surface sites, towers, aircraft, and soundings from the Total Carbon Column Observing Network (TCCON). Extensive evaluations of the L3 reanalysis clearly demonstrate both the strength and the deficiency of the satellite retrievals. Second, it is possible to estimate variables from the reanalysis without introducing bias due to spatiotemporal variability in sounding coverage. For example, the assimilated product provides robust estimates of the monthly CO2 global growth rate. These monthly growth rate estimates show significant differences from estimates based on in situ observations, which have sparse coverage, and those based on model surface fluxes, which imperfectly represent key processes. This presentation discusses the implications of this finding as well as ongoing strategies to extract more information from the satellite retrievals in future L3 reanalyses.

Blocking germanium diffusion inside silicon dioxide using a co-implanted silicon barrier

NASA Astrophysics Data System (ADS)

Barba, D.; Wang, C.; Nélis, A.; Terwagne, G.; Rosei, F.

2018-04-01

We investigate the effect of co-implanting a silicon sublayer on the thermal diffusion of germanium ions implanted into SiO2 and the growth of Ge nanocrystals (Ge-ncs). High-resolution imaging obtained by transmission electron microscopy and energy dispersive spectroscopy measurements supported by Monte-Carlo calculations shows that the Si-enriched region acts as a diffusion barrier for Ge atoms. This barrier prevents Ge outgassing during thermal annealing at 1100 °C. Both the localization and the reduced size of Ge-ncs formed within the sample region co-implanted with Si are observed, as well as the nucleation of mixed Ge/Si nanocrystals containing structural point defects and stacking faults. Although it was found that the Si co-implantation affects the crystallinity of the formed Ge-ncs, this technique can be implemented to produce size-selective and depth-ordered nanostructured systems by controlling the spatial distribution of diffusing Ge. We illustrate this feature for Ge-ncs embedded within a single SiO2 monolayer, whose diameters were gradually increased from 1 nm to 5 nm over a depth of 100 nm.

Cathodoluminescence of rare earth implanted Ga2O3 and GeO2 nanostructures.

PubMed

Nogales, E; Hidalgo, P; Lorenz, K; Méndez, B; Piqueras, J; Alves, E

2011-07-15

Rare earth (RE) doped gallium oxide and germanium oxide micro- and nanostructures, mostly nanowires, have been obtained and their morphological and optical properties have been characterized. Undoped oxide micro- and nanostructures were grown by a thermal evaporation method and were subsequently doped with gadolinium or europium ions by ion implantation. No significant changes in the morphologies of the nanostructures were observed after ion implantation and thermal annealing. The luminescence emission properties have been studied with cathodoluminescence (CL) in a scanning electron microscope (SEM). Both β-Ga(2)O(3) and GeO(2) structures implanted with Eu show the characteristic red luminescence peak centered at around 610 nm, due to the (5)D(0)-(7)F(2) Eu(3+) intraionic transition. Sharpening of the luminescence peaks after thermal annealing is observed in Eu implanted β-Ga(2)O(3), which is assigned to the lattice recovery. Gd(3+) as-implanted samples do not show rare earth related luminescence. After annealing, optical activation of Gd(3+) is obtained in both matrices and a sharp ultraviolet peak centered at around 315 nm, associated with the Gd(3+) (6)P(7/2)-(8)S(7/2) intraionic transition, is observed. The influence of the Gd ion implantation and the annealing temperature on the gallium oxide broad intrinsic defect band has been analyzed.

Synthesis of dual porous structured germanium anodes with exceptional lithium-ion storage performance

NASA Astrophysics Data System (ADS)

Kwon, Dohyoung; Ryu, Jaegeon; Shin, Myungsoo; Song, Gyujin; Hong, Dongki; Kim, Kwang S.; Park, Soojin

2018-01-01

Dual-porous Ge nanostructures are synthesized via two straightforward steps. Compared with conventional approaches related to porous Ge materials, different types of pores can be readily generated by adjusting the relative ratio of the precursor amounts for GeO2 and SiO2. Unlike using hard templates with different sizes for introducing secondary pores, this system makes a uniformly blended structure of porogen and active sites in the nanoscale range. When GeO2 is subjected to zincothermic reduction, it is selectively converted to pure Ge still connected to unreacted SiO2. During the reduction process, primary pores (larger than 50 nm) are formed by eliminating zinc oxide by-products, while inactive SiO2 with respect to zinc metal could contribute to retaining the overall structure. Finally, the HF treatment completely leaches remaining SiO2 and formed secondary pores (micro/mesopores) to complete the dual-porous Ge structure. The resulting Ge structure is tested as an anode material for lithium-ion batteries. The Ge electrode exhibits an outstanding reversibility and an exceptional cycling stability corresponding to a capacity retention of 100% after 100 cycles at C/5 and of 94.4% after 300 cycles at C/2. Furthermore, multi-scale pores facilitate a facile Li-ion accessibility, resulting in an excellent rate capability delivering ∼740 mAh g-1 at 5C.

First-principles study of the stability of free-standing germanene in oxygen atmosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, G.; College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang 330022; Liu, S. B., E-mail: sbliu@bjut.edu.cn

2015-09-28

The O{sub 2} dissociation and O atoms adsorption on free-standing germanene are studied by using first-principles calculations in this paper. Compared with the extremely active silicene in oxygen atmosphere, germanene is found to be less active due to an energy barrier for dissociation of about 0.57 eV. Moreover, the dissociated oxygen atom follows two opposite migration pathways on the germanene surface, which is quite different from the case of silicene. Furthermore, the migration and desorption of O atoms at room temperature are relatively difficult due to the strong Ge-O bonding, resulting in the formation of germanium oxides. Our results reveal themore » interplay between germanene and O{sub 2} and suggest the enhanced stability of germanene in oxygen atmosphere compared with silicene.« less

SO2 Emissions and Lifetimes: Estimates from Inverse Modeling Using In Situ and Global, Space-Based (SCIAMACHY and OMI) Observations

NASA Technical Reports Server (NTRS)

Lee, Chulkyu; Martin Randall V.; vanDonkelaar, Aaron; Lee, Hanlim; Dickerson, RUssell R.; Hains, Jennifer C.; Krotkov, Nickolay; Richter, Andreas; Vinnikov, Konstantine; Schwab, James J.

2011-01-01

Top-down constraints on global sulfur dioxide (SO2) emissions are inferred through inverse modeling using SO2 column observations from two satellite instruments (SCIAMACHY and OMI). We first evaluated the S02 column observations with surface SO2 measurements by applying local scaling factors from a global chemical transport model (GEOS-Chem) to SO2 columns retrieved from the satellite instruments. The resulting annual mean surface SO2 mixing ratios for 2006 exhibit a significant spatial correlation (r=0.86, slope=0.91 for SCIAMACHY and r=0.80, slope = 0.79 for OMI) with coincident in situ measurements from monitoring networks throughout the United States and Canada. We evaluate the GEOS-Chem simulation of the SO2 lifetime with that inferred from in situ measurements to verity the applicability of GEOS-Chem for inversion of SO2 columns to emissions. The seasonal mean SO2 lifetime calculated with the GEOS-Chem model over the eastern United States is 13 h in summer and 48 h in winter, compared to lifetimes inferred from in situ measurements of 19 +/- 7 h in summer and 58 +/- 20 h in winter. We apply SO2 columns from SCIAMACHY and OMI to derive a top-down anthropogenic SO2 emission inventory over land by using the local GEOS-Chem relationship between SO2 columns and emissions. There is little seasonal variation in the top-down emissions (<15%) over most major industrial regions providing some confidence in the method. Our global estimate for annual land surface anthropogenic SO2 emissions (52.4 Tg S/yr from SCIAMACHY and 49.9 Tg S / yr from OMI) closely agrees with the bottom-up emissions (54.6 Tg S/yr) in the GEOS-Chem model and exhibits consistency in global distributions with the bottom-up emissions (r = 0.78 for SCIAMACHY, and r = 0.77 for OMI). However, there are significant regional differences.

Evaluation of simulated biospheric carbon dioxide fluxes and atmospheric concentrations using global in situ observations

NASA Astrophysics Data System (ADS)

Philip, S.; Johnson, M. S.; Potter, C. S.; Genovese, V. B.

2016-12-01

Atmospheric mixing ratios of carbon dioxide (CO2) are largely controlled by anthropogenic emission sources and biospheric sources/sinks. Global biospheric fluxes of CO2 are controlled by complex processes facilitating the exchange of carbon between terrestrial ecosystems and the atmosphere. These processes which play a key role in these terrestrial ecosystem-atmosphere carbon exchanges are currently not fully understood, resulting in large uncertainties in the quantification of biospheric CO2 fluxes. Current models with these inherent deficiencies have difficulties simulating the global carbon cycle with high accuracy. We are developing a new modeling platform, GEOS-Chem-CASA by integrating the year-specific NASA-CASA (National Aeronautics and Space Administration - Carnegie Ames Stanford Approach) biosphere model with the GEOS-Chem (Goddard Earth Observation System-Chemistry) chemical transport model to improve the simulation of atmosphere-terrestrial ecosystem carbon exchange. We use NASA-CASA to explicitly represent the exchange of CO2 between terrestrial ecosystem and atmosphere by replacing the baseline GEOS-Chem land net CO2 flux and forest biomass burning CO2 emissions. We will present the estimation and evaluation of these "bottom-up" land CO2 fluxes, simulated atmospheric mixing ratios, and forest disturbance changes over the last decade. In addition, we will present our initial comparison of atmospheric column-mean dry air mole fraction of CO2 predicted by the model and those retrieved from NASA's OCO-2 (Orbiting Carbon Observatory-2) satellite instrument and model-predicted surface CO2 mixing ratios with global in situ observations. This evaluation is the first step necessary for our future work planned to constrain the estimates of biospheric carbon fluxes through "top-down" inverse modeling, which will improve our understanding of the processes controlling atmosphere-terrestrial ecosystem greenhouse gas exchanges, especially over regions which lack in situ observations.

B33C-0612: Evaluation of Simulated Biospheric Carbon Dioxide Fluxes and Atmospheric Concentrations Using Global in Situ Observations

NASA Technical Reports Server (NTRS)

Philip, Sajeev; Johnson, Matthew S.; Potter, Christopher S.; Genovese, Vanessa

2016-01-01

Atmospheric mixing ratios of carbon dioxide (CO2) are largely controlled by anthropogenic emission sources and biospheric sources/sinks. Global biospheric fluxes of CO2 are controlled by complex processes facilitating the exchange of carbon between terrestrial ecosystems and the atmosphere. These processes which play a key role in these terrestrial ecosystem-atmosphere carbon exchanges are currently not fully understood, resulting in large uncertainties in the quantification of biospheric CO2 fluxes. Current models with these inherent deficiencies have difficulties simulating the global carbon cycle with high accuracy. We are developing a new modeling platform, GEOS-Chem-CASA by integrating the year-specific NASA-CASA (National Aeronautics and Space Administration - Carnegie Ames Stanford Approach) biosphere model with the GEOS-Chem (Goddard Earth Observation System-Chemistry) chemical transport model to improve the simulation of atmosphere-terrestrial ecosystem carbon exchange. We use NASA-CASA to explicitly represent the exchange of CO2 between terrestrial ecosystem and atmosphere by replacing the baseline GEOS-Chem land net CO2 flux and forest biomass burning CO2 emissions. We will present the estimation and evaluation of these "bottom-up" land CO2 fluxes, simulated atmospheric mixing ratios, and forest disturbance changes over the last decade. In addition, we will present our initial comparison of atmospheric column-mean dry air mole fraction of CO2 predicted by the model and those retrieved from NASA's OCO-2 (Orbiting Carbon Observatory-2) satellite instrument and model-predicted surface CO2 mixing ratios with global in situ observations. This evaluation is the first step necessary for our future work planned to constrain the estimates of biospheric carbon fluxes through "top-down" inverse modeling, which will improve our understanding of the processes controlling atmosphere-terrestrial ecosystem greenhouse gas exchanges, especially over regions which lack in situ observations.

Germanium diffusion with vapor-phase GeAs and oxygen co-incorporation in GaAs

NASA Astrophysics Data System (ADS)

Wang, Wei-Fu; Cheng, Kai-Yuan; Hsieh, Kuang-Chien

2018-01-01

Vapor-phase germanium diffusion has been demonstrated in Zn-doped and semi-insulating GaAs in sealed ampoules with GeAs powders and excess arsenic. Secondary-ion-mass spectroscopy (SIMS) profiles indicate the presence of unintentional co-incorporation of oxygen in high densities (>1017/cm3) along with diffused germanium donors whose concentration (>>1018/cm3) determined by electro-chemical capacitance-voltage (ECV) profiler shows significant compensation near the surface. The source of oxygen mainly originates from the GeAs powder which contains Ge-O surface oxides. Variable-temperature photoluminescence (PL) shows that in GeAs-diffused samples, a broad peak ranging from 0.86-1.38 eV with the peak position around 1.1 eV predominates at low temperatures while the near band-edge luminescence quenches. The broad band is attributed to the GeGa-VGa self-activated (SA) centers possibly associated with nearby oxygen-related defect complex, and its luminescence persists up to 400 K. The configurational-coordinate modeling finds that the SA defect complex has a thermal activation energy of 150-180 meV and a vibrational energy 26.8 meV. The presence of oxygen does not much affect the SA emission intensity but may have influenced the peak position, vibration frequency and activation energy as compared to other common donor-VGa defects in GaAs.

Source Attribution of Near-surface Ozone in the Western US: Improved Estimates by TF HTAP2 Multi-model Experiment and Multi-scale Chemical Data Assimilation

NASA Astrophysics Data System (ADS)

Huang, M.; Bowman, K. W.; Carmichael, G. R.; Lee, M.; Park, R.; Henze, D. K.; Chai, T.; Flemming, J.; Lin, M.; Weinheimer, A. J.; Wisthaler, A.; Jaffe, D. A.

2014-12-01

Near-surface ozone in the western US can be sensitive to transported background pollutants from the free troposphere over the eastern Pacific, as well as various local emissions sources. Accurately estimating ozone source contributions in this region has strong policy-relevant significance as the air quality standards tend to go down. Here we improve modeled contributions from local and non-local sources to western US ozone base on the HTAP2 (Task Force on Hemispheric Transport of Air Pollution) multi-model experiment, along with multi-scale chemical data assimilation. We simulate western US air quality using the STEM regional model on a 12 km horizontal resolution grid, during the NASA ARCTAS field campaign period in June 2008. STEM simulations use time-varying boundary conditions downscaled from global GEOS-Chem model simulations. Standard GEOS-Chem simulation overall underpredicted ozone at 1-5 km in the eastern Pacific, resulting in underestimated contributions from the transported background pollutants to surface ozone inland. These negative biases can be reduced by using the output from several global models that support the HTAP2 experiment, which all ran with the HTAP2 harmonized emission inventory and also calculated the contributions from east Asian anthropogenic emissions. We demonstrate that the biases in GEOS-Chem boundary conditions can be more efficiently reduced via assimilating satellite ozone profiles from the Tropospheric Emission Spectrometer (TES) instrument using the three dimensional variational (3D-Var) approach. Base upon these TES-constrained GEOS-Chem boundary conditions, we then update regional nitrogen dioxide and isoprene emissions in STEM through the four dimensional variational (4D-Var) assimilation of the Ozone Monitoring Instrument (OMI) nitrogen dioxide columns and the NASA DC-8 aircraft isoprene measurements. The 4D-Var assimilation spatially redistributed the emissions of nitrogen oxides and isoprene from various US sources, and in the meantime updated the modeled ozone and its US source contributions. Compared with available independent measurements (e.g., ozone observed on the DC-8 aircraft, and at EPA and Mt. Bachelor monitoring stations) during this period, modeled ozone fields after the multi-scale assimilation show overall improvement.

The Geostationary Fourier Transform Spectrometer

NASA Technical Reports Server (NTRS)

Key, Richard; Sander, Stanley; Eldering, Annmarie; Blavier, Jean-Francois; Bekker, Dmitriy; Manatt, Ken; Rider, David; Wu, Yen-Hung

2012-01-01

The Geostationary Fourier Transform Spectrometer (GeoFTS) is an imaging spectrometer designed for a geostationary orbit (GEO) earth science mission to measure key atmospheric trace gases and process tracers related to climate change and human activity. GEO allows GeoFTS to continuously stare at a region of the earth for frequent sampling to capture the variability of biogenic fluxes and anthropogenic emissions from city to continental spatial scales and temporal scales from diurnal, synoptic, seasonal to interannual. The measurement strategy provides a process based understanding of the carbon cycle from contiguous maps of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), and chlorophyll fluorescence (CF) collected many times per day at high spatial resolution (2.7kmx2.7km at nadir). The CO2/CH4/CO/CF measurement suite in the near infrared spectral region provides the information needed to disentangle natural and anthropogenic contributions to atmospheric carbon concentrations and to minimize uncertainties in the flow of carbon between the atmosphere and surface. The half meter cube size GeoFTS instrument is based on a Michelson interferometer design that uses all high TRL components in a modular configuration to reduce complexity and cost. It is self-contained and as independent of the spacecraft as possible with simple spacecraft interfaces, making it ideal to be a "hosted" payload on a commercial communications satellite mission. The hosted payload approach for measuring the major carbon-containing gases in the atmosphere from the geostationary vantage point will affordably advance the scientific understating of carbon cycle processes and climate change.

Ultra-Pure Water and Extremophilic Bacteria interactions with Germanium Surfaces

NASA Astrophysics Data System (ADS)

Sah, Vasu R.

Supported by a consortium of semiconductor industry sponsors, an international "TIE" project among 5 National Science Foundation (NSF) Industry/university Cooperative Research Centers discovered that a particular extremophilic microbe, Pseudomonas syzygii, persists in the UltraPure Water (UPW) supplies of chip fabrication facilities (FABs) and can bio-corrode germanium wafers to produce microbe-encased optically transparent crystals. Considered as potentially functional "biochips", this investigation explored mechanisms for the efficient and deliberate production of such microbe-germania adducts as a step toward later testing of their properties as sensors or switches in bioelectronic or biophotonic circuits. Recirculating UPW (Ultra-Pure Water) and other purified water, laminar-flow loops were developed across 50X20x1mm germanium (Ge) prisms, followed by subsequent examination of the prism surfaces using Multiple Attenuated Internal Reflection InfraRed (MAIR-IR) spectroscopy, Contact Potential measurements, Differential Interference Contrast Light Microscopy (DICLM), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDS), and Electron Spectroscopy for Chemical Analysis (ESCA; XPS). P. syzygii cultures originally obtained from a working FAB at University of Arizona were successfully grown on R2A minimal nutrient media. They were found to be identical to the microbes in stored UPW from the same facility, such microbes routinely capable of nucleation and entrapment within GeO2 crystals on the Ge flow surfaces. Optimum flow rates and exposure times were 1 ml/minute (3.2 s-1 shear rate) for 4 days at room temperature, producing densest crystal arrays at the prism central zones 2-3 cm from the flow inlets. Other flow rates and exposure times have higher shear rate which induces a different nucleation mechanism and saturation of crystal formation. Nucleation events began with square and circular oxide deposits surrounding active attached bacteria, presumably in response to diffusing or spreading metabolic products. They germinated into amorphous germania moats around square crystalline growths incorporating bacteria in the ring centers, sometimes in multiples. Further distances of UPW flow along the prism faces showed both amorphous phase dissolution and crystal "ripening", followed by some crystal shedding and downstream secondary collections of crystal clusters. Microscopic viewing allowed micromanipulator-directed fine wire contacts with individual crystals to assess their electrical characteristics, with limited data due to the ceramic-like refractory properties of the germania crystals. A schematic is presented for the events of nucleation and crystal growth observed, offering the interpretation that Ge oxidation to GeO2 occurs from UV-dissociated water corroding the Ge surface while releasing protons that can drive the metabolic processes keeping the extremophilic organisms alive. It is likely that other extremophilic microorganisms can be similarly entrapped within semiconductor crystals. Further work is now required to discriminate between nucleation by microbial exudates and by the microbial surfaces directly, and to interrogate the crystals grown with advanced electronic and biophotonic probes.

EPA True NO2 ground site measurements ?? multiple sites, TCEQ ground site measurements of meteorological and air pollution parameters ?? multiple sites ,GeoTASO NO2 Vertical Column

EPA Pesticide Factsheets

EPA True NO2 ground site measurements ?? multiple sites - http://www-air.larc.nasa.gov/cgi-bin/ArcView/discover-aq.tx-2013; TCEQ ground site measurements of meteorological and air pollution parameters ?? multiple sites - http://www-air.larc.nasa.gov/cgi-bin/ArcView/discover-aq.tx-2013; GeoTASO NO2 Vertical Column - http://www-air.larc.nasa.gov/cgi-bin/ArcView/discover-aq.tx-2013?FALCON=1This dataset is associated with the following publication:Nowlan, C., X. Lu, J. Leitch, K. Chance, G. González Abad, C. Lu, P. Zoogman, J. Cole, T. Delker, W. Good, F. Murcray, L. Ruppert, D. Soo, M. Follette-Cook, S. Janz, M. Kowalewski, C. Loughner, K. Pickering, J. Herman, M. Beaver, R. Long, J. Szykman, L. Judd, P. Kelley, W. Luke, X. Ren, and J. Al-Saadi. Nitrogen dioxide observations from the Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) airborne instrument: Retrieval algorithm and measurements during DISCOVER-AQ Texas 2013. Atmospheric Measurement Techniques. Copernicus Publications, Katlenburg-Lindau, GERMANY, 9(6): 2647-2668, (2016).

High-contrast germanium-doped silica-on-silicon waveguides

NASA Astrophysics Data System (ADS)

Dumais, Patrick; Callender, Claire; Blanchetière, Chantal; Ledderhof, Chris

2012-10-01

Silica-on-silicon planar lightwave circuits have a number of advantages including stability and low insertion loss to optical fiber networks. Standard GeO2 doping levels in the waveguide cores lead to a refractive index contrast, n/n, of 0.75%-2%. This range of index contrast requires relatively large bend radii in order to minimize bend losses. This limits the density scaling of these circuits. By using high dopant levels for a Δn/n of 4%, the bend radius can be decreased to less than 1 mm, from which significant gains in optical circuit density can be obtained. In addition, low-loss ring resonators with free spectral ranges of a few tens of gigahertz can be realized, enabling some additional optical signal processing and filtering on that scale. Optical devices with such high dopant levels have been reported by Bellman et al. in 2004 [1] but to the authors' knowledge, no other experimental work on high-delta GeO2-doped waveguides has been reported since. In this paper, we present experimental measurements on high-delta devices including directional couplers, MMI couplers, Mach-Zehnder interferometers, and ring resonators. Device performance, including propagation loss, bend loss, interferometer contrast ratio and birefringence will be presented. We demonstrate that ring resonators with 40 GHz free spectral range can be fabricated for optical signal processing.

Seismicity triggered by the olivine-spinel transition: New insights from combined XRD and acoustic emission monitoring during deformation experiments in Mg2GeO4

NASA Astrophysics Data System (ADS)

Schubnel, A. J.; Hilairet, N.; Gasc, J.; Héripré, E.; Brunet, F.; Wang, Y.

2010-12-01

Polycrystalline Mg2GeO4-olivine has been deformed (strain rates from 2.10-4/s to 10-5/s) in the deformation-DIA in 13-BM-D at GSECARS (Advanced Photon Source) at ca. 2 GPa confining pressure for temperatures between 973 and 1573 K (i.e., in the Mg2GeO4-ringwoodite field). Stress, advancement of transformation, and strain were measured in-situ using X-ray diffraction (XRD) and imaging, and acoustic emissions (AE) full waveforms were recorded simultaneously. When differential stress is applied (ca. 1- to 2 GPa) and temperature is increased, the very beginning of the transformation to the ringwoodite structure (as evidenced by in situ XRD) is accompanied by AE bursts which locate within the sample. At high strain rates (>10-4/s) and low temperatures (800-900 degrees C), the number of AEs is comparable, if not larger, to that observed during the cold compression of quartz grains. The largest events always occur at a temperature slightly below that of appearance of the ringwoodite-structure phase on the XRD images patterns. This suggests that AEs are generated while the transition is still nucleation controlled (pseudo-martensitic stage). During stress-relaxation periods, the rate of AE triggering decreases, but does not completely vanish. The AE production rate increases again as soon as deformation is started again. Importantly, we still observed very large AEs at strain rates as low as approx. 10-5/ s. At these early stages of the transformation, the samples did not show any macroscopic rheological weakening. Focal mechanism analysis of the largest AEs showed that they are all of shear type, some being even pure double couple. They radiate about the same amount of energy as typically recorded during fast crack propagation in amorphous glass material. This suggests that they cannot only originate from the martensitic nucleation of oriented spinel-lamellae within a single germanium olivine crystal. Preliminary microstructural analysis (SEM and EBSD) highlights the presence of thin transformation bands made of incoherent spinel micro-grains which, possibly, run across germanium-olivine grain boundaries. These bands are all oriented near perpendicular to the principal compressive stress. Our observations point out that under high deviatoric stress, the olivine - spinel transition is a source of instability which produces micro-sismicity (no AEs were recorded in a similar experiment performed hydrostatically). These instabilities might eventually be precursor to brittle fracturing as observed by Green and Burnley (1989) in their deformation experiments on very similar samples. Both types of study emphasize the potential of phase transitions (with negative volume variations) in triggering brittle failure. Obviously, this has important consequences for the understanding of deep-focus earthquakes occurring in cold and metastable olivine within the transition zone.

Research Investigation Directed Toward Extending the Useful Range of the Electromagnetic Spectrum.

DTIC Science & Technology

1987-12-31

spectrometer ions photoionic emission threshold low temperature processing low energy ion beam silicon oxidation sputtering of silicon dioxide germanium...Osgood, "Optically-Induced, Room- Temperature Oxidation of Gallium Arsenide," Mat. Res. Soc. Symp. Proc. 75(1987):251-255. P. D. Brewer and R. M. Osgood... oxide films (40-70 A) at room temperature which are suitable for MOSFET devices, has been extensively studied experimentally and theoretically. The

The Germanium Dichotomy in Martian Meteorites

NASA Technical Reports Server (NTRS)

Humayun, M.; Yang, S.; Righter, K.; Zanda, B.; Hewins, R. H.

2016-01-01

Germanium is a moderately volatile and siderophile element that follows silicon in its compatibility during partial melting of planetary mantles. Despite its obvious usefulness in planetary geochemistry germanium is not analyzed routinely, with there being only three prior studies reporting germanium abundances in Martian meteorites. The broad range (1-3 ppm) observed in Martian igneous rocks is in stark contrast to the narrow range of germanium observed in terrestrial basalts (1.5 plus or minus 0.1 ppm). The germanium data from these studies indicates that nakhlites contain 2-3 ppm germanium, while shergottites contain approximately 1 ppm germanium, a dichotomy with important implications for core formation models. There have been no reliable germanium abundances on chassignites. The ancient meteoritic breccia, NWA 7533 (and paired meteorites) contains numerous clasts, some pristine and some impact melt rocks, that are being studied individually. Because germanium is depleted in the Martian crust relative to chondritic impactors, it has proven useful as an indicator of meteoritic contamination of impact melt clasts in NWA 7533. The germanium/silicon ratio can be applied to minerals that might not partition nickel and iridium, like feldspars. We report germanium in minerals from the 3 known chassignites, 2 nakhlites and 5 shergottites by LAICP- MS using a method optimized for precise germanium analysis.

The Geostationary Fourier Transform Spectrometer

NASA Technical Reports Server (NTRS)

Key, Richard; Sander, Stanley; Eldering, Annmarie; Miller, Charles; Frankenberg, Christian; Natra, Vijay; Rider, David; Blavier, Jean-Francois; Bekker, Dmitriy; Wu, Yen-Hung

2012-01-01

The Geostationary Fourier Transform Spectrometer (GeoFTS) is an imaging spectrometer designed for an earth science mission to measure key atmospheric trace gases and process tracers related to climate change and human activity. The GeoFTS instrument is a half meter cube size instrument designed to operate in geostationary orbit as a secondary "hosted" payload on a commercial geostationary satellite mission. The advantage of GEO is the ability to continuously stare at a region of the earth, enabling frequent sampling to capture the diurnal variability of biogenic fluxes and anthropogenic emissions from city to continental scales. The science goal is to obtain a process-based understanding of the carbon cycle from simultaneous high spatial resolution measurements of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), and chlorophyll fluorescence (CF) many times per day in the near infrared spectral region to capture their spatial and temporal variations on diurnal, synoptic, seasonal and interannual time scales. The GeoFTS instrument is based on a Michelson interferometer design with a number of advanced features incorporated. Two of the most important advanced features are the focal plane arrays and the optical path difference mechanism. A breadboard GeoFTS instrument has demonstrated functionality for simultaneous measurements in the visible and IR in the laboratory and subsequently in the field at the California Laboratory for Atmospheric Remote Sensing (CLARS) observatory on Mt. Wilson overlooking the Los Angeles basin. A GeoFTS engineering model instrument is being developed which will make simultaneous visible and IR measurements under space flight like environmental conditions (thermal-vacuum at 180 K). This will demonstrate critical instrument capabilities such as optical alignment stability, interferometer modulation efficiency, and high throughput FPA signal processing. This will reduce flight instrument development risk and show that the GeoFTS design is mature and flight ready.

Air Quality Modeling Using the NASA GEOS-5 Multispecies Data Assimilation System

NASA Technical Reports Server (NTRS)

Keller, Christoph A.; Pawson, Steven; Wargan, Krzysztof; Weir, Brad

2018-01-01

The NASA Goddard Earth Observing System (GEOS) data assimilation system (DAS) has been expanded to include chemically reactive tropospheric trace gases including ozone (O3), nitrogen dioxide (NO2), and carbon monoxide (CO). This system combines model analyses from the GEOS-5 model with detailed atmospheric chemistry and observations from MLS (O3), OMI (O3 and NO2), and MOPITT (CO). We show results from a variety of assimilation test experiments, highlighting the improvements in the representation of model species concentrations by up to 50% compared to an assimilation-free control experiment. Taking into account the rapid chemical cycling of NO2 when applying the assimilation increments greatly improves assimilation skills for NO2 and provides large benefits for model concentrations near the surface. Analysis of the geospatial distribution of the assimilation increments suggest that the free-running model overestimates biomass burning emissions but underestimates lightning NOx emissions by 5-20%. We discuss the capability of the chemical data assimilation system to improve atmospheric composition forecasts through improved initial value and boundary condition inputs, particularly during air pollution events. We find that the current assimilation system meaningfully improves short-term forecasts (1-3 day). For longer-term forecasts more emphasis on updating the emissions instead of initial concentration fields is needed.

An emission-weighted proximity model for air pollution exposure assessment.

PubMed

Zou, Bin; Wilson, J Gaines; Zhan, F Benjamin; Zeng, Yongnian

2009-08-15

Among the most common spatial models for estimating personal exposure are Traditional Proximity Models (TPMs). Though TPMs are straightforward to configure and interpret, they are prone to extensive errors in exposure estimates and do not provide prospective estimates. To resolve these inherent problems with TPMs, we introduce here a novel Emission Weighted Proximity Model (EWPM) to improve the TPM, which takes into consideration the emissions from all sources potentially influencing the receptors. EWPM performance was evaluated by comparing the normalized exposure risk values of sulfur dioxide (SO(2)) calculated by EWPM with those calculated by TPM and monitored observations over a one-year period in two large Texas counties. In order to investigate whether the limitations of TPM in potential exposure risk prediction without recorded incidence can be overcome, we also introduce a hybrid framework, a 'Geo-statistical EWPM'. Geo-statistical EWPM is a synthesis of Ordinary Kriging Geo-statistical interpolation and EWPM. The prediction results are presented as two potential exposure risk prediction maps. The performance of these two exposure maps in predicting individual SO(2) exposure risk was validated with 10 virtual cases in prospective exposure scenarios. Risk values for EWPM were clearly more agreeable with the observed concentrations than those from TPM. Over the entire study area, the mean SO(2) exposure risk from EWPM was higher relative to TPM (1.00 vs. 0.91). The mean bias of the exposure risk values of 10 virtual cases between EWPM and 'Geo-statistical EWPM' are much smaller than those between TPM and 'Geo-statistical TPM' (5.12 vs. 24.63). EWPM appears to more accurately portray individual exposure relative to TPM. The 'Geo-statistical EWPM' effectively augments the role of the standard proximity model and makes it possible to predict individual risk in future exposure scenarios resulting in adverse health effects from environmental pollution.

A COMSOL-GEMS interface for modeling coupled reactive-transport geochemical processes

NASA Astrophysics Data System (ADS)

Azad, Vahid Jafari; Li, Chang; Verba, Circe; Ideker, Jason H.; Isgor, O. Burkan

2016-07-01

An interface was developed between COMSOL MultiphysicsTM finite element analysis software and (geo)chemical modeling platform, GEMS, for the reactive-transport modeling of (geo)chemical processes in variably saturated porous media. The two standalone software packages are managed from the interface that uses a non-iterative operator splitting technique to couple the transport (COMSOL) and reaction (GEMS) processes. The interface allows modeling media with complex chemistry (e.g. cement) using GEMS thermodynamic database formats. Benchmark comparisons show that the developed interface can be used to predict a variety of reactive-transport processes accurately. The full functionality of the interface was demonstrated to model transport processes, governed by extended Nernst-Plank equation, in Class H Portland cement samples in high pressure and temperature autoclaves simulating systems that are used to store captured carbon dioxide (CO2) in geological reservoirs.

Rheology and microstructure of magmatic emulsions - Theory and experiments

NASA Technical Reports Server (NTRS)

Stein, Daniel J.; Spera, Frank J.

1992-01-01

The rheological properties of a dilute mixture of melt plus vapor bubbles, referred to as emulsion, are investigated theoretically and in rheometric experiments on dilute viscous germanium dioxide emulsions at temperatures between 1100 and 1175 C and at 100 kPa pressure in a rotating rod rheometer at shear rates between 0.05/s and 7/s. The results indicate that the emulsions may be described by a power-law constitutive relation when observations cover a sufficient range of shear rates to resolve nonlinear flow.

A Study of the Carbon Cycle Using NASA Observations and the GEOS Model

NASA Technical Reports Server (NTRS)

Pawson, Steven; Gelaro, Ron; Ott, Lesley; Putman, Bill; Chatterjee, Abhishek; Koster, Randy; Lee, Eunjee; Oda, Tom; Weir, Brad; Zeng, Fanwei

2018-01-01

The Goddard Earth Observing System (GEOS) model has been developed in the Global Modeling and Assimilation Office (GMAO) at NASA's Goddard Space Flight Center. From its roots in chemical transport and as a General Circulation Model, the GEOS model has been extended to an Earth System Model based on a modular construction using the Earth System Modeling Framework (ESMF), combining elements developed in house in the GMAO with others that are imported through collaborative research. It is used extensively for research and for product generation, both as a free-running model and as the core of the GMAO's data assimilation system. In recent years, the GMAO's modeling and assimilation efforts have been strongly supported by Piers Sellers, building on both his earlier legacy as an observationally oriented model developer and his post-astronaut career as a dynamic leader into new territory. Piers' long-standing interest in the carbon cycle and the combination of models with observations motivates this presentation, which will focus on the representation of the carbon cycle in the GEOS Earth System Model. Examples will include: (i) the progression from specified land-atmosphere surface fluxes to computations with an interactive model component (Catchment-CN), along with constraints on vegetation distributions using satellite observations; (ii) the use of high-resolution satellite observations to constrain human-generated inputs to the atmosphere; (iii) studies of the consistency of the observed atmospheric carbon dioxide concentrations with those in the model simulations. The presentation will focus on year-to-year variations in elements of the carbon cycle, specifically on how the observations can inform the representation of mechanisms in the model and lead to integrity in global carbon dioxide simulations. Further, applications of the GEOS model to the planning of new carbon-climate observations will be addressed, as an example of the work that was strongly supported by Piers in the last months of his leadership of Earth Science at NASA Goddard.

High-quality photonic crystals with a nearly complete band gap obtained by direct inversion of woodpile templates with titanium dioxide.

PubMed

Marichy, Catherine; Muller, Nicolas; Froufe-Pérez, Luis S; Scheffold, Frank

2016-02-25

Photonic crystal materials are based on a periodic modulation of the dielectric constant on length scales comparable to the wavelength of light. These materials can exhibit photonic band gaps; frequency regions for which the propagation of electromagnetic radiation is forbidden due to the depletion of the density of states. In order to exhibit a full band gap, 3D PCs must present a threshold refractive index contrast that depends on the crystal structure. In the case of the so-called woodpile photonic crystals this threshold is comparably low, approximately 1.9 for the direct structure. Therefore direct or inverted woodpiles made of high refractive index materials like silicon, germanium or titanium dioxide are sought after. Here we show that, by combining multiphoton lithography and atomic layer deposition, we can achieve a direct inversion of polymer templates into TiO2 based photonic crystals. The obtained structures show remarkable optical properties in the near-infrared region with almost perfect specular reflectance, a transmission dip close to the detection limit and a Bragg length comparable to the lattice constant.

Power Satellites, Carbon Dioxide, Synthetic Fuel, Sequestering Carbon as Synthetic Oil and Fresh Water from Seawater

NASA Astrophysics Data System (ADS)

Keith Henson, H.

2010-05-01

A small number of people have been working for the past year on ways to reduce the cost of power from space to the point that it could entirely displace fossil fuels and even put carbon dioxide back in empty oil fields as synthetic oil. The challenging part is reducing the cost of transport to GEO by a factor of ˜200 discussed in another paper in this volume. Given low cost power, synthetic fuels, carbon sequestration, and fresh water from seawater become economical.

Analyzing carbon dioxide and methane emissions in California using airborne measurements and model simulations

NASA Astrophysics Data System (ADS)

Johnson, M. S.; Yates, E. L.; Iraci, L. T.; Jeong, S.; Fischer, M. L.

2013-12-01

Greenhouse gas (GHG) concentrations have increased over the past decades and are linked to global temperature increases and climate change. These changes in climate have been suggested to have varying effects, and uncertain consequences, on agriculture, water supply, weather, sea-level rise, the economy, and energy. To counteract the trend of increasing atmospheric concentrations of GHGs, the state of California has passed the California Global Warming Act of 2006 (AB-32). This requires that by the year 2020, GHG (e.g., carbon dioxide (CO2) and methane (CH4)) emissions will be reduced to 1990 levels. To quantify GHG fluxes, emission inventories are routinely compiled for the State of California (e.g., CH4 emissions from the California Greenhouse Gas Emissions Measurement (CALGEM) Project). The major sources of CO2 and CH4 in the state of California are: transportation, electricity production, oil and gas extraction, cement plants, agriculture, landfills/waste, livestock, and wetlands. However, uncertainties remain in these emission inventories because many factors contributing to these processes are poorly quantified. To alleviate these uncertainties, a synergistic approach of applying air-borne measurements and chemical transport modeling (CTM) efforts to provide a method of quantifying local and regional GHG emissions will be performed during this study. Additionally, in order to further understand the temporal and spatial distributions of GHG fluxes in California and the impact these species have on regional climate, CTM simulations of daily variations and seasonality of total column CO2 and CH4 will be analyzed. To assess the magnitude and spatial variation of GHG emissions and to identify local 'hot spots', airborne measurements of CH4 and CO2 were made by the Alpha Jet Atmospheric eXperiment (AJAX) over the San Francisco Bay Area (SFBA) and San Joaquin Valley (SJV) in January and February 2013 during the Discover-AQ-CA study. High mixing ratios of GHGs were observed in-flight with a high degree of spatial variability. To provide an additional method to quantify GHG emissions, and analyze AJAX measurement data, the GEOS-Chem CTM is used to simulate SFBA/SJV GHG measurements. A nested-grid version of GEOS-Chem will be applied and utilizes varying emission inventories and model parameterizations to simulate GHG fluxes/emissions. The model considers CO2 fluxes from fossil fuel use, biomass/biofuel burning, terrestrial and oceanic biosphere exchanges, shipping and aviation, and production from the oxidation of carbon monoxide, CH4, and non-methane volatile organic carbons. The major sources of CH4 simulated in GEOS-Chem are domesticated animals, rice fields, natural gas leakage, natural gas venting/flaring (oil production), coal mining, wetlands, and biomass burning. Preliminary results from the comparison between available observations (e.g., AJAX and CALGEM CH4 emission maps) and GEOS-Chem results will be presented, along with a discussion of CO2 and CH4 source apportionment and the use of the GEOS-Chem-adjoint to perform inverse GHG modeling.

Explicit and Observation-based Aerosol Treatment in Tropospheric NO2 Retrieval over China from the Ozone Monitoring Instrument

NASA Astrophysics Data System (ADS)

Liu, M.; Lin, J.; Boersma, F.; Pinardi, G.; Wang, Y.; Chimot, J.; Wagner, T.; Xie, P.; Eskes, H.; Van Roozendael, M.; Hendrick, F.

2017-12-01

Satellite retrieval of vertical column densities (VCDs) of tropospheric nitrogen dioxide (NO2) is influenced by aerosols substantially. Aerosols affect the retrieval of "effective cloud fraction (CF)" and "effective cloud top pressure (CP)" that are used in the subsequent NO2 retrieval to account for the presentence of clouds. And aerosol properties and vertical distributions directly affect the NO2 air mass factor (AMF) calculations. Our published POMINO algorithm uses a parallelized LIDORT-driven AMFv6 code to derive CF, CP and NO2 VCD. Daily information on aerosol optical properties are taken from GEOS-Chem simulations, with aerosol optical depth (AOD) further constrained by monthly MODIS AOD. However, the published algorithm does not include an observation-based constraint of aerosol vertical distribution. Here we construct a monthly climatological observation dataset of aerosol extinction profiles, based on Level-2 CALIOP data over 2007-2015, to further constrain aerosol vertical distributions. GEOS-Chem captures the temporal variations of CALIOP aerosol layer heights (ALH) but has an overall underestimate by about 0.3 km. It tends to overestimate the aerosol extinction by 10% below 2 km but with an underestimate by 30% above 2 km, leading to a low bias by 10-30% in the retrieved tropospheric NO2 VCD. After adjusting GEOS-Chem aerosol extinction profiles by the CALIOP monthly ALH climatology, the retrieved NO2 VCDs increase by 4-16% over China on a monthly basis in 2012. The improved NO2 VCDs are better correlated to independent MAX-DOAS observations at three sites than POMINO and DOMINO are - especially for the polluted cases, R2 reaches 0.76 for the adjusted POMINO, much higher than that for the published POMINO (0.68) and DOMINO (0.38). The newly retrieved CP increases by 60 hPa on average, because of a stronger aerosol screening effect. Compared to the CF used in DOMINO, which implicitly includes aerosol information, our improved CF is much lower and can reach a value of zero on actual cloud-free days. Overall, constraining aerosol vertical profiles greatly improves the retrievals of clouds and NO2 VCDs from satellite remote sensing. Our algorithm can be applied, with minimum modifications, to formaldehyde, sulfur dioxide and other species with similar retrieval methodologies.

Developing a Carbon Observing System

NASA Astrophysics Data System (ADS)

Moore, B., III

2015-12-01

There is a clear need to better understand and predict future climate change, so that science can more confidently inform climate policy, including adaptation planning and future mitigation strategies. Understanding carbon cycle feedbacks, and the relationship between emissions (fossil and land use) and the resulting atmospheric carbon dioxide (CO2) and methane (CH4) concentrations in a changing climate has been recognized as an important goal by the IPCC. The existing surface greenhouse gas observing networks provide accurate and precise measurements of background values, but they are not configured to target the extended, complex and dynamic regions of the carbon budget. Space Agencies around the globe are committed to CO2 and CH4 observations: GOSAT-1/2, OCO-2/3, MERLin, TanSat, and CarbonSat. In addition to these Low Earth Orbit (LEO) missions, a new mission in Geostationary Orbit (GEO), geoCARB, which would provide mapping-like measurements of carbon dioxide, methane, and carbon monoxide concentrations over major land areas, has been recently proposed to the NASA Venture Program. These pioneering missions do not provide the spatial/temporal coverage to answer the key carbon-climate questions at process relevant scales nor do they address the distribution and quantification of anthropogenic sources at urban scales. They do demonstrate, however, that a well-planned future system of system integrating space-based LEO and GEO missions with extensive in situ observations could provide the accuracy, spatial resolution, and coverage needed to address critical open issues in the carbon-climate system. Dr. Diana Wickland devoted enormous energy in developing a comprehensive apprioach to understand the global carbon cycle; she understood well that an integrated, coordinated, international approach is needed. This shines through in her recent contribution in co-chairing the team that produced the "CEOS Strategy for Carbon Observations from Space." A NASA-funded community workshop in March 2015 addressed issues and prioritzed a set of research and observational needs in the study of the Carbon-Climate System. This paper will refect upon the past 30 plus years of carbon research supported by NASA and Dr. Wickland's role, and it will conclude with the findings of the March 2015 Workshop.

A new Geoengineering Model Intercomparison Project (GeoMIP) experiment designed for climate and chemistry models

DOE PAGES

Tilmes, S.; Mills, Mike; Niemeier, Ulrike; ...

2015-01-15

A new Geoengineering Model Intercomparison Project (GeoMIP) experiment "G4 specified stratospheric aerosols" (short name: G4SSA) is proposed to investigate the impact of stratospheric aerosol geoengineering on atmosphere, chemistry, dynamics, climate, and the environment. In contrast to the earlier G4 GeoMIP experiment, which requires an emission of sulfur dioxide (SO₂) into the model, a prescribed aerosol forcing file is provided to the community, to be consistently applied to future model experiments between 2020 and 2100. This stratospheric aerosol distribution, with a total burden of about 2 Tg S has been derived using the ECHAM5-HAM microphysical model, based on a continuous annualmore » tropical emission of 8 Tg SO₂ yr⁻¹. A ramp-up of geoengineering in 2020 and a ramp-down in 2070 over a period of 2 years are included in the distribution, while a background aerosol burden should be used for the last 3 decades of the experiment. The performance of this experiment using climate and chemistry models in a multi-model comparison framework will allow us to better understand the impact of geoengineering and its abrupt termination after 50 years in a changing environment. The zonal and monthly mean stratospheric aerosol input data set is available at https://www2.acd.ucar.edu/gcm/geomip-g4-specified-stratospheric-aerosol-data-set.« less

Secondary ion formation during electronic and nuclear sputtering of germanium

NASA Astrophysics Data System (ADS)

Breuer, L.; Ernst, P.; Herder, M.; Meinerzhagen, F.; Bender, M.; Severin, D.; Wucher, A.

2018-06-01

Using a time-of-flight mass spectrometer attached to the UNILAC beamline located at the GSI Helmholtz Centre for Heavy Ion Research, we investigate the formation of secondary ions sputtered from a germanium surface under irradiation by swift heavy ions (SHI) such as 5 MeV/u Au by simultaneously recording the mass spectra of the ejected secondary ions and their neutral counterparts. In these experiments, the sputtered neutral material is post-ionized via single photon absorption from a pulsed, intensive VUV laser. After post-ionization, the instrument cannot distinguish between secondary ions and post-ionized neutrals, so that both signals can be directly compared in order to investigate the ionization probability of different sputtered species. In order to facilitate an in-situ comparison with typical nuclear sputtering conditions, the system is also equipped with a conventional rare gas ion source delivering a 5 keV argon ion beam. For a dynamically sputter cleaned surface, it is found that the ionization probability of Ge atoms and Gen clusters ejected under electronic sputtering conditions is by more than an order of magnitude higher than that measured for keV sputtered particles. In addition, the mass spectra obtained under SHI irradiation show prominent signals of GenOm clusters, which are predominantly detected as positive or negative secondary ions. From the m-distribution for a given Ge nuclearity n, one can deduce that the sputtered material must originate from a germanium oxide matrix with approximate GeO stoichiometry, probably due to residual native oxide patches even at the dynamically cleaned surface. The results clearly demonstrate a fundamental difference between the ejection and ionization mechanisms in both cases, which is interpreted in terms of corresponding model calculations.

Remote Sensing from Geostationary Orbit: GEO TROPSAT, A New Concept for Atmospheric Remote Sensing

NASA Technical Reports Server (NTRS)

Little, Alan D.; Neil, Doreen O.; Sachse, Glen W.; Fishman, Jack; Krueger, Arlin J.

1997-01-01

The Geostationary Tropospheric Pollution Satellite (GEO TROPSAT) mission is a new approach to measuring the critical constituents of tropospheric ozone chemistry: ozone, carbon monoxide, nitrogen dioxide, and aerosols. The GEO TROPSAT mission comprises a constellation of three instruments flying as secondary payloads on geostationary communications satellites around the world. This proposed approach can significantly reduce the cost of getting a science payload to geostationary orbit and also generates revenue for the satellite owners. The geostationary vantage point enables simultaneous high temporal and spatial resolution measurement of tropospheric trace gases, leading to greatly improved atmospheric ozone chemistry knowledge. The science data processing, conducted as a research (not operational) activity, will provide atmospheric trace gas data many times per day over the same region at better than 25 km ground footprint. The high temporal resolution identifies short time scale processes, diurnal variations, seasonal trends, and interannual variation.

Geographical Information Systems (GIS) Mapping of Environmental Samples across College Campuses

ERIC Educational Resources Information Center

Purvis-Roberts, Kathleen L.; Moeur, Harriet P.; Zanella, Andrew

2007-01-01

In this laboratory experiment, students take environmental samples at various locations around the college campuses, take geospatial coordinates with a global position systems (GPS) unit, and map their results on a geo-referenced campus map with geographical information systems (GIS) software. Nitrogen dioxide air pollution sampling is used as an…

Vapor pressure of germanium precursors

NASA Astrophysics Data System (ADS)

Pangrác, J.; Fulem, M.; Hulicius, E.; Melichar, K.; Šimeček, T.; Růžička, K.; Morávek, P.; Růžička, V.; Rushworth, S. A.

2008-11-01

The vapor pressure of two germanium precursors tetrakis(methoxy)germanium (Ge(OCH 3) 4, CASRN 992-91-6) and tetrakis(ethoxy)germanium (Ge(OC 2H 5) 4, CASRN 14165-55-0) was determined using a static method in the temperature range 259-303 K. The experimental vapor pressure data were fit with the Antoine equation. The mass spectra before and after degassing by vacuum distillation at low temperature are also reported and discussed.

Time integrated optical emission studies of the laser produced germanium plasma

NASA Astrophysics Data System (ADS)

Iqbal, Javed; Ahmed, R.; Baig, M. A.

2017-04-01

We present new time integrated data on the optical emission spectra of laser produced germanium plasma using a Q-switched Nd:YAG laser (1064 nm), power density up to about 5  ×  109 W cm-2 in conjunction with a set of five spectrometers covering a spectral range from 200 nm to 720 nm. Well resolved structure due to the 4p5s  →  4p2 transition array of neutral germanium and a few multiplets of singly ionized germanium have been observed. Plasma temperature has been determined in the range (9000-11 000) K using four different techniques; two line ratio method, Boltzmann plot, Saha-Boltzmann plot and Marotta’s technique whereas electron density has been deduced from the Stark broadened line profiles in the range (0.5-5.0)  ×  1017 cm-3, depending on the laser pulse energy to produce the germanium plasma. Full width at half maximum (FWHM) of a number of neutral and singly ionized germanium lines have been extracted by the Lorentzian fit to the experimentally observed line profiles. In addition, we have compared the experimentally measured relative line strengths for the 4p5s 3P0,1,2  →  4p2 3P0,1,2 multiplet with that calculated in the LS-coupling scheme revealing that the intermediate coupling scheme is more appropriate for the level designations in germanium.

Hydrogen Sensor Based on Pd/GeO{sub 2} Using a Low Cost Electrochemical Deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jawad, M. J.; Hashim, M. R.; Ali, N. K.

2011-05-25

This work reports on a synthesis of sub micron germanium dioxide (GeO{sub 2}) on porous silicon (PS) by electrochemical deposition. n-type Si (100) wafer was used to fabricate (PS) using conventional method of electrochemical etching in HF based solution. A GeCl{sub 4} was directly hydrolyzed by hydrogen peroxide to produce pure GeO{sub 2}, and then electrochemically deposited on PS. Followed by palladium (Pd) contact on GeO{sub 2} /PS was achieved by using RF sputtering technique. The grown GeO{sub 2} crystals were characterized using SEM and EDX. I-V characteristics of Pd/ GeO{sub 2} were recorded before and after hydrogen gas exposuremore » as well as with different H{sub 2} concentrations and different applied temperatures. The sensitivity of Pd/ GeO{sub 2} also has been investigated it could be seen to increase significantly with increased hydrogen concentration while it decreased with increase temperature.« less

Terraforming the Planets and Climate Change Mitigation on Earth

NASA Astrophysics Data System (ADS)

Toon, O. B.

2008-12-01

Hopefully, purposeful geo-engineering of the Earth will remain a theoretical concept. Of course, we have already inadvertently changed the Earth, and over geologic history life has left an indelible imprint on our planet. We can learn about geo-engineering schemes by reference to Earth history, for example climate changes after volcanic eruptions provide important clues to using sulfates to modify the climate. The terrestrial planets and Titan offer additional insights. For instance, Mars and Venus both have carbon dioxide dominated greenhouses. Both have more than 10 times as much carbon dioxide in their atmospheres as Earth, and both absorb less sunlight than Earth, yet one is much colder than Earth and one is much hotter. These facts provide important insights into carbon dioxide greenhouses that I will review. Mars cools dramatically following planet wide dust storms, and Titan has what is referred to as an anti- greenhouse climate driven by aerosols. These data can be used to reassure us that we can model aerosol caused changes to the climate of a planet, and also provide examples of aerosols offsetting a gas-driven greenhouse effect. People have long considered whether we might make the other planets habitable. While most of the schemes considered belong in the realm of science fiction, it is possible that some schemes might be practical. Terraforming brings to mind a number of issues that are thought provoking, but not so politically charged as geo-engineering. For example: What criteria define habitability, is it enough for people to live in isolated glass enclosures, or do we need to walk freely on the planet? Different creatures have different needs. Is a planet habitable if plants can thrive in the open, or do animals also need to be free? Are the raw materials present on any planet to make it habitable? If not, can we make the materials, or do we have to import them? Is it ethical to change a planetary climate? What if there are already primitive creatures hidden somewhere, does that change the ethics? Or perhaps, if left alone, the planet would later evolve to have life, is it ethical to alter that path? Many of these questions have parallels to things we need to consider when we talk about geo-engineering Earth. I will touch upon some of these subjects in this talk.

Impact of a regional drought on terrestrial carbon fluxes and atmospheric carbon: results from a coupled carbon cycle model

NASA Astrophysics Data System (ADS)

Lee, E.; Koster, R. D.; Ott, L. E.; Weir, B.; Mahanama, S. P. P.; Chang, Y.; Zeng, F.

2017-12-01

Understanding the underlying processes that control the carbon cycle is key to predicting future global change. Much of the uncertainty in the magnitude and variability of the atmospheric carbon dioxide (CO2) stems from uncertainty in terrestrial carbon fluxes. Budget-based analyses show that such fluxes exhibit substantial interannual variability, but the relative impacts of temperature and moisture variations on regional and global scales are poorly understood. Here we investigate the impact of a regional drought on terrestrial carbon fluxes and CO2 mixing ratios over North America using the NASA Goddard Earth Observing System (GEOS) Model. Two 48-member ensembles of NASA GEOS-5 simulations with fully coupled land and atmosphere carbon components are performed - a control ensemble and an ensemble with an artificially imposed dry land surface anomaly for three months (April-June) over the lower Mississippi River Valley. Comparison of the results using the ensemble approach allows a direct quantification of the impact of the regional drought on local and proximate carbon exchange at the land surface via the carbon-water feedback processes.

Research on Utilization of Geo-Energy

NASA Astrophysics Data System (ADS)

Bock, Michaela; Scheck-Wenderoth, Magdalena; GeoEn Working Group

2013-04-01

The world's energy demand will increase year by year and we have to search for alternative energy resources. New concepts concerning the energy production from geo-resources have to be provided and developed. The joint project GeoEn combines research on the four core themes geothermal energy, shale gas, CO2 capture and CO2 storage. Sustainable energy production from deep geothermal energy resources is addressed including all processes related to geothermal technologies, from reservoir exploitation to energy conversion in the power plant. The research on the unconventional natural gas resource, shale gas, is focussed on the sedimentological, diagenetic and compositional characteristics of gas shales. Technologies and solutions for the prevention of the greenhouse gas carbon dioxide are developed in the research fields CO2 capture technologies, utilization, transport, and CO2 storage. Those four core themes are studied with an integrated approach using the synergy of cross-cutting methodologies. New exploration and reservoir technologies and innovative monitoring methods, e.g. CSMT (controlled-source magnetotellurics) are examined and developed. All disciplines are complemented by numerical simulations of the relevant processes. A particular strength of the project is the availability of large experimental infrastructures where the respective technologies are tested and monitored. These include the power plant Schwarze Pumpe, where the Oxyfuel process is improved, the pilot storage site for CO2 in Ketzin and the geothermal research platform Groß Schönebeck, with two deep wells and an experimental plant overground for research on corrosion. In addition to fundamental research, the acceptance of new technologies, especially in the field of CCS is examined. Another focus addressed is the impact of shale gas production on the environment. A further important goal is the education of young scientists in the new field "geo-energy" to fight skills shortage in this field of growing economic and ecologic relevance.

Germanium: From Its Discovery to SiGe Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haller, E.E.

2006-06-14

Germanium, element No.32, was discovered in 1886 by Clemens Winkler. Its first broad application was in the form of point contact Schottky diodes for radar reception during WWII. The addition of a closely spaced second contact led to the first all-solid-state electronic amplifier device, the transistor. The relatively low bandgap, the lack of a stable oxide and large surface state densities relegated germanium to the number 2 position behind silicon. The discovery of the lithium drift process, which made possible the formation of p-i-n diodes with fully depletable i-regions several centimeters thick, led germanium to new prominence as the premiermore » gamma-ray detector. The development of ultra-pure germanium yielded highly stable detectors which have remained unsurpassed in their performance. New acceptors and donors were discovered and the electrically active role of hydrogen was clearly established several years before similar findings in silicon. Lightly doped germanium has found applications as far infrared detectors and heavily Neutron Transmutation Doped (NTD) germanium is used in thermistor devices operating at a few milliKelvin. Recently germanium has been rediscovered by the silicon device community because of its superior electron and hole mobility and its ability to induce strains when alloyed with silicon. Germanium is again a mainstream electronic material.« less

Germanium recovery from gasification fly ash: evaluation of end-products obtained by precipitation methods.

PubMed

Arroyo, Fátima; Font, Oriol; Fernández-Pereira, Constantino; Querol, Xavier; Juan, Roberto; Ruiz, Carmen; Coca, Pilar

2009-08-15

In this study the purity of the germanium end-products obtained by two different precipitation methods carried out on germanium-bearing solutions was evaluated as a last step of a hydrometallurgy process for the recovery of this valuable element from the Puertollano Integrated Gasification Combined Cycle (IGCC) fly ash. Since H(2)S is produced as a by-product in the gas cleaning system of the Puertollano IGCC plant, precipitation of germanium as GeS(2) was tested by sulfiding the Ge-bearing solutions. The technological and hazardous issues that surround H(2)S handling conducted to investigate a novel precipitation procedure: precipitation as an organic complex by adding 1,2-dihydroxy benzene pyrocatechol (CAT) and cetyltrimethylammonium bromide (CTAB) to the Ge-bearing solutions. Relatively high purity Ge end-products (90 and 93% hexagonal-GeO(2) purity, respectively) were obtained by precipitating Ge from enriched solutions, as GeS(2) sulfiding the solutions with H(2)S, or as organic complex with CAT/CTAB mixtures and subsequent roasting of the precipitates. Both methods showed high efficiency (>99%) to precipitate selectively Ge using a single precipitation stage from germanium-bearing solutions.

System study of the carbon dioxide observational platform system (CO-OPS): Project overview

NASA Technical Reports Server (NTRS)

Stephens, J. Briscoe; Thompson, Wilbur E.

1987-01-01

The resulting options from a system study for a near-space, geo-stationary, observational monitoring platform system for use in the Department of Energy's (DOE) National Carbon Dioxide Observational Platform System (CO-OPS) on the greenhouse effect are discussed. CO-OPS is being designed to operate continuously for periods of up to 3 months in quasi-fixed position over most global regional targets of interest and could make horizon observations over a land-sea area of circular diameter up to about 600 to 800 statute miles. This affords the scientific and engineering community a low-cost means of operating their payloads for monitoring the regional parameters they deem relevant to their investigations of the carbon dioxide greenhouse effect at one-tenth the cost of most currently utilized comparable remote sensing techniques.

Tropospheric Emissions: Monitoring of Pollution (TEMPO)

NASA Technical Reports Server (NTRS)

Zoogman, P.; Liu, X.; Suleiman, R. M.; Pennington, W. F.; Flittner, D. E.; Al-Saadi, J. A.; Hilton, B. B.; Nicks, D. K.; Newchurch, M. J.; Carr, J. L.;

Tropospheric emissions: Monitoring of pollution (TEMPO)

NASA Astrophysics Data System (ADS)

Zoogman, P.; Liu, X.; Suleiman, R. M.; Pennington, W. F.; Flittner, D. E.; Al-Saadi, J. A.; Hilton, B. B.; Nicks, D. K.; Newchurch, M. J.; Carr, J. L.; Janz, S. J.; Andraschko, M. R.; Arola, A.; Baker, B. D.; Canova, B. P.; Chan Miller, C.; Cohen, R. C.; Davis, J. E.; Dussault, M. E.; Edwards, D. P.; Fishman, J.; Ghulam, A.; González Abad, G.; Grutter, M.; Herman, J. R.; Houck, J.; Jacob, D. J.; Joiner, J.; Kerridge, B. J.; Kim, J.; Krotkov, N. A.; Lamsal, L.; Li, C.; Lindfors, A.; Martin, R. V.; McElroy, C. T.; McLinden, C.; Natraj, V.; Neil, D. O.; Nowlan, C. R.; O`Sullivan, E. J.; Palmer, P. I.; Pierce, R. B.; Pippin, M. R.; Saiz-Lopez, A.; Spurr, R. J. D.; Szykman, J. J.; Torres, O.; Veefkind, J. P.; Veihelmann, B.; Wang, H.; Wang, J.; Chance, K.

2017-01-01

TEMPO was selected in 2012 by NASA as the first Earth Venture Instrument, for launch between 2018 and 2021. It will measure atmospheric pollution for greater North America from space using ultraviolet and visible spectroscopy. TEMPO observes from Mexico City, Cuba, and the Bahamas to the Canadian oil sands, and from the Atlantic to the Pacific, hourly and at high spatial resolution ( 2.1 km N/S×4.4 km E/W at 36.5°N, 100°W). TEMPO provides a tropospheric measurement suite that includes the key elements of tropospheric air pollution chemistry, as well as contributing to carbon cycle knowledge. Measurements are made hourly from geostationary (GEO) orbit, to capture the high variability present in the diurnal cycle of emissions and chemistry that are unobservable from current low-Earth orbit (LEO) satellites that measure once per day. The small product spatial footprint resolves pollution sources at sub-urban scale. Together, this temporal and spatial resolution improves emission inventories, monitors population exposure, and enables effective emission-control strategies. TEMPO takes advantage of a commercial GEO host spacecraft to provide a modest cost mission that measures the spectra required to retrieve ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), formaldehyde (H2CO), glyoxal (C2H2O2), bromine monoxide (BrO), IO (iodine monoxide), water vapor, aerosols, cloud parameters, ultraviolet radiation, and foliage properties. TEMPO thus measures the major elements, directly or by proxy, in the tropospheric O3 chemistry cycle. Multi-spectral observations provide sensitivity to O3 in the lowermost troposphere, substantially reducing uncertainty in air quality predictions. TEMPO quantifies and tracks the evolution of aerosol loading. It provides these near-real-time air quality products that will be made publicly available. TEMPO will launch at a prime time to be the North American component of the global geostationary constellation of pollution monitoring together with the European Sentinel-4 (S4) and Korean Geostationary Environment Monitoring Spectrometer (GEMS) instruments.

Influence of Containment on the Growth of Silicon-Germanium: A Materials Science Flight Project

NASA Technical Reports Server (NTRS)

Volz, M. P.; Mazuruk, K.; Croell, A.

2012-01-01

This investigation involves the comparison of results achieved from three types of crystal growth of germanium and germanium-silicon alloys: (1) Float zone growth (2) Bridgman growth (3) Detached Bridgman growth crystal The fundamental goal of the proposed research is to determine the influence of containment on the processing-induced defects and impurity incorporation in germanium-silicon (GeSi) crystals (silicon concentration in the solid up to 5 at%) for three different growth configurations in order to quantitatively assess the improvements of crystal quality possible by detached growth.

Impacts of light shading and nutrient enrichment geo-engineering approaches on the productivity of a stratified, oligotrophic ocean ecosystem.

PubMed

Hardman-Mountford, Nick J; Polimene, Luca; Hirata, Takafumi; Brewin, Robert J W; Aiken, Jim

2013-12-06

Geo-engineering proposals to mitigate global warming have focused either on methods of carbon dioxide removal, particularly nutrient fertilization of plant growth, or on cooling the Earth's surface by reducing incoming solar radiation (shading). Marine phytoplankton contribute half the Earth's biological carbon fixation and carbon export in the ocean is modulated by the actions of microbes and grazing communities in recycling nutrients. Both nutrients and light are essential for photosynthesis, so understanding the relative influence of both these geo-engineering approaches on ocean ecosystem production and processes is critical to the evaluation of their effectiveness. In this paper, we investigate the relationship between light and nutrient availability on productivity in a stratified, oligotrophic subtropical ocean ecosystem using a one-dimensional water column model coupled to a multi-plankton ecosystem model, with the goal of elucidating potential impacts of these geo-engineering approaches on ecosystem production. We find that solar shading approaches can redistribute productivity in the water column but do not change total production. Macronutrient enrichment is able to enhance the export of carbon, although heterotrophic recycling reduces the efficiency of carbon export substantially over time. Our results highlight the requirement for a fuller consideration of marine ecosystem interactions and feedbacks, beyond simply the stimulation of surface blooms, in the evaluation of putative geo-engineering approaches.

Impacts of light shading and nutrient enrichment geo-engineering approaches on the productivity of a stratified, oligotrophic ocean ecosystem

PubMed Central

Hardman-Mountford, Nick J.; Polimene, Luca; Hirata, Takafumi; Brewin, Robert J. W.; Aiken, Jim

2013-01-01

Geo-engineering proposals to mitigate global warming have focused either on methods of carbon dioxide removal, particularly nutrient fertilization of plant growth, or on cooling the Earth's surface by reducing incoming solar radiation (shading). Marine phytoplankton contribute half the Earth's biological carbon fixation and carbon export in the ocean is modulated by the actions of microbes and grazing communities in recycling nutrients. Both nutrients and light are essential for photosynthesis, so understanding the relative influence of both these geo-engineering approaches on ocean ecosystem production and processes is critical to the evaluation of their effectiveness. In this paper, we investigate the relationship between light and nutrient availability on productivity in a stratified, oligotrophic subtropical ocean ecosystem using a one-dimensional water column model coupled to a multi-plankton ecosystem model, with the goal of elucidating potential impacts of these geo-engineering approaches on ecosystem production. We find that solar shading approaches can redistribute productivity in the water column but do not change total production. Macronutrient enrichment is able to enhance the export of carbon, although heterotrophic recycling reduces the efficiency of carbon export substantially over time. Our results highlight the requirement for a fuller consideration of marine ecosystem interactions and feedbacks, beyond simply the stimulation of surface blooms, in the evaluation of putative geo-engineering approaches. PMID:24132201

File Specification for the MERRA Aerosol Reanalysis (MERRAero): MODIS AOD Assimilation based on a MERRA Replay

NASA Technical Reports Server (NTRS)

Da Silva, A. M.; Randles, C. A.; Buchard, V.; Darmenov, A.; Colarco, P. R.; Govindaraju, R.

2015-01-01

This document describes the gridded output files produced by the Goddard Earth Observing System version 5 (GEOS-5) Goddard Aerosol Assimilation System (GAAS) from July 2002 through December 2014. The MERRA Aerosol Reanalysis (MERRAero) is produced with the hydrostatic version of the GEOS-5 Atmospheric Global Climate Model (AGCM). In addition to standard meteorological parameters (wind, temperature, moisture, surface pressure), this simulation includes 15 aerosol tracers (dust, sea-salt, sulfate, black and organic carbon), ozone, carbon monoxide and carbon dioxide. This model simulation is driven by prescribed sea-surface temperature and sea-ice, daily volcanic and biomass burning emissions, as well as high-resolution inventories of anthropogenic emission sources. Meteorology is replayed from the MERRA Reanalysis.

Study of the possibility of growing germanium single crystals under low temperature gradients

NASA Astrophysics Data System (ADS)

Moskovskih, V. A.; Kasimkin, P. V.; Shlegel, V. N.; Vasiliev, Y. V.; Gridchin, V. A.; Podkopaev, O. I.; Zhdankov, V. N.

2014-03-01

The possibility of growing germanium single crystals under low temperature gradients in order to produce a dislocation-free material has been studied. Germanium crystals with a dislocation density of about 100-200 cm-2 have been grown in a system with a weight control of crystal growth at maximum axial gradients of about 1.5 K/cm.

EVALUATION OF THE IMPACT OF THE DEFENSE WASTE PROCESSING FACILITY (DWPF) LABORATORY GERMANIUM OXIDE USE ON RECYCLE TRANSFERS TO THE H-TANK FARM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jantzen, C.; Laurinat, J.

2011-08-15

When processing High Level Waste (HLW) glass, the Defense Waste Processing Facility (DWPF) cannot wait until the melt or waste glass has been made to assess its acceptability, since by then no further changes to the glass composition and acceptability are possible. Therefore, the acceptability decision is made on the upstream feed stream, rather than on the downstream melt or glass product. This strategy is known as 'feed forward statistical process control.' The DWPF depends on chemical analysis of the feed streams from the Sludge Receipt and Adjustment Tank (SRAT) and the Slurry Mix Evaporator (SME) where the frit plusmore » adjusted sludge from the SRAT are mixed. The SME is the last vessel in which any chemical adjustments or frit additions can be made. Once the analyses of the SME product are deemed acceptable, the SME product is transferred to the Melter Feed Tank (MFT) and onto the melter. The SRAT and SME analyses have been analyzed by the DWPF laboratory using a 'Cold Chemical' method but this dissolution did not adequately dissolve all the elemental components. A new dissolution method which fuses the SRAT or SME product with cesium nitrate (CsNO{sub 3}), germanium (IV) oxide (GeO{sub 2}) and cesium carbonate (Cs{sub 2}CO{sub 3}) into a cesium germanate glass at 1050 C in platinum crucibles has been developed. Once the germanium glass is formed in that fusion, it is readily dissolved by concentrated nitric acid (about 1M) to solubilize all the elements in the SRAT and/or SME product for elemental analysis. When the chemical analyses are completed the acidic cesium-germanate solution is transferred from the DWPF analytic laboratory to the Recycle Collection Tank (RCT) where the pH is increased to {approx}12 M to be released back to the tank farm and the 2H evaporator. Therefore, about 2.5 kg/yr of GeO{sub 2}/year will be diluted into 1.4 million gallons of recycle. This 2.5 kg/yr of GeO{sub 2} may increase to 4 kg/yr when improvements are implemented to attain an annual canister production goal of 400 canisters. Since no Waste Acceptance Criteria (WAC) exists for germanium in the Tank Farm, the Effluent Treatment Project, or the Saltstone Production Facility, DWPF has requested an evaluation of the fate of the germanium in the caustic environment of the RCT, the 2H evaporator, and the tank farm. This report evaluates the effect of the addition of germanium to the tank farm based on: (1) the large dilution of Ge in the RCT and tank farm; (2) the solubility of germanium in caustic solutions (pH 12-13); (3) the potential of germanium to precipitate as germanium sodalites in the 2H Evaporator; and (4) the potential of germanium compounds to precipitate in the evaporator feed tank. This study concludes that the impacts of transferring up to 4 kg/yr germanium to the RCT (and subsequently the 2H evaporator feed tank and the 2H evaporator) results in <2 ppm per year (1.834 mg/L) which is the maximum instantaneous concentration expected from DWPF. This concentration is insignificant as most sodium germanates are soluble at the high pH of the feed tank and evaporator solutions. Even if sodium aluminosilicates form in the 2H evaporator, the Ge will likely substitute for some small amount of the Si in these structures and will be insignificant. It is recommended that the DWPF continue with their strategy to add germanium as a laboratory chemical to Attachment 8.2 of the DWPF Waste Compliance Plan (WCP).« less

Slow Crack Growth of Germanium

NASA Technical Reports Server (NTRS)

Salem, Jon

2016-01-01

The fracture toughness and slow crack growth parameters of germanium supplied as single crystal beams and coarse grain disks were measured. Although germanium is anisotropic (A=1.7), it is not as anisotropic as SiC, NiAl, or Cu, as evidence by consistent fracture toughness on the 100, 110, and 111 planes. Germanium does not exhibit significant slow crack growth in distilled water. (n=100). Practical values for engineering design are a fracture toughness of 0.7 MPam and a Weibull modulus of m=6+/-2. For well ground and reasonable handled coupons, fracture strength should be greater than 30 MPa.

The low thermal gradient CZ technique as a way of growing of dislocation-free germanium crystals

NASA Astrophysics Data System (ADS)

Moskovskih, V. A.; Kasimkin, P. V.; Shlegel, V. N.; Vasiliev, Y. V.; Gridchin, V. A.; Podkopaev, O. I.

2014-09-01

This paper considers the possibility of growth of dislocation-free germanium single crystals. This is achieved by reducing the temperature gradients at the level of 1 K/cm and lower. Single germanium crystals 45-48 mm in diameter with a dislocation density of 102 cm-2 were grown by a Low Thermal Gradient Czochralski technique (LTG CZ).

Synthesis, surface properties and antimicrobial activity of some germanium nonionic surfactants.

PubMed

Zaki, Mohamed F; Tawfik, Salah M

2014-01-01

Esterification reaction between different fatty acid namely; lauric, stearic, oleic and linoleic acids and polyethylene glycol-400 were performed. The produced polyethylene glycol ester were reacted with p-amine benzoic acid followed by condensation reaction with germanium dioxide in presence of sodium carbonate to form desired germinate surfactants. The chemical structures of the synthesized surfactants were determined using different spectra tools. The surface parameter including: the critical micelle concentration (CMC), effectiveness (π(cmc)), efficiency (Pc20), maximum surface excess (Γ(max)) and minimum surface area (A(min)), were calculated from the surface tension measurements. The synthesized surfactants showed higher surface activity. The thermodynamic parameters showed that adsorption and micellization processes are spontaneous. It is clear that the synthesized nonionic surfactants showed their tendency towards adsorption at the interfaces and also micellization in the bulk of their solutions. The synthesized surfactants were tested against different strain of bacteria using inhibition zone diameters. The synthesized surfactants showed good antimicrobial activities against the tested microorganisms including Gram positive, Gram negative as well as fungi. The promising inhibition efficiency of these compounds against the sulfate reducing bacteria facilitates them to be applicable as new categories of sulfate reducing bacteria biocides.

Germanium recycling in the United States in 2000

USGS Publications Warehouse

Jorgenson, John D.

2006-01-01

This report describes the recycling flow of germanium in the United States in 2000, as well as other germanium material flow streams. Germanium was recycled mostly from new scrap that was generated during the manufacture of germanium-containing fiber optic cables and from new and old scrap products of germanium-containing infrared imaging devices. In 2000, about 11.5 metric tons of germanium was recycled, about 40 percent of which was derived from old scrap. The germanium recycling rate was estimated to be 50 percent, and germanium scrap recycling efficiency, 76 percent.

Modifications of the Quasi-biennial Oscillation by a Geoengineering Perturbation of the Stratospheric Aerosol Layer

NASA Technical Reports Server (NTRS)

Aquila, V.; Garfinkel, C. I.; Newman, P. A.; Oman, L. D.; Waugh, D. W.

2014-01-01

This paper examines the impact of geoengineering via stratospheric sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System (GEOS-5) Chemistry Climate Model. We performed four 30-year simulations with a continuous injection of sulfur dioxide on the equator at 0 degree longitude. The four simulations differ by the amount of sulfur dioxide injected (5Tg per year and 2.5 Tg per year) and the altitude of the injection (16km-25km and 22km-25km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. In the case of maximum perturbation, i.e. highest stratospheric aerosol burden, the lower tropical stratosphere is locked into a permanent westerly QBO phase. This locked QBO westerly phase is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere.

Changes in the width of the tropical belt due to simple radiative forcing changes in the GeoMIP simulations

NASA Astrophysics Data System (ADS)

Davis, Nicholas A.; Seidel, Dian J.; Birner, Thomas; Davis, Sean M.; Tilmes, Simone

2016-08-01

Model simulations of future climates predict a poleward expansion of subtropical arid climates at the edges of Earth's tropical belt, which would have significant environmental and societal impacts. This expansion may be related to the poleward shift of the Hadley cell edges, where subsidence stabilizes the atmosphere and suppresses precipitation. Understanding the primary drivers of tropical expansion is hampered by the myriad forcing agents in most model projections of future climate. While many previous studies have examined the response of idealized models to simplified climate forcings and the response of comprehensive climate models to more complex climate forcings, few have examined how comprehensive climate models respond to simplified climate forcings. To shed light on robust processes associated with tropical expansion, here we examine how the tropical belt width, as measured by the Hadley cell edges, responds to simplified forcings in the Geoengineering Model Intercomparison Project (GeoMIP). The tropical belt expands in response to a quadrupling of atmospheric carbon dioxide concentrations and contracts in response to a reduction in the solar constant, with a range of a factor of 3 in the response among nine models. Models with more surface warming and an overall stronger temperature response to quadrupled carbon dioxide exhibit greater tropical expansion, a robust result in spite of inter-model differences in the mean Hadley cell width, parameterizations, and numerical schemes. Under a scenario where the solar constant is reduced to offset an instantaneous quadrupling of carbon dioxide, the Hadley cells remain at their preindustrial width, despite the residual stratospheric cooling associated with elevated carbon dioxide levels. Quadrupled carbon dioxide produces greater tropical belt expansion in the Southern Hemisphere than in the Northern Hemisphere. This expansion is strongest in austral summer and autumn. Ozone depletion has been argued to cause this pattern of changes in observations and model experiments, but the results here indicate that seasonally and hemispherically asymmetric tropical expansion can be a basic response of the general circulation to climate forcings.

Application of vacuum reduction and chlorinated distillation to enrich and prepare pure germanium from coal fly ash.

PubMed

Zhang, Lingen; Xu, Zhenming

2017-01-05

Germanium, as strategic reserve metal, plays critical role in high-tech industry. However, a contradiction of increasing consumption and scarcity of germanium resource is becoming more and more prominent. This paper proposed an integrated process to recycle germanium from coal fly ash. This technological process mainly consisted of two procedures: vacuum reduction with the purposes of enriching germanium and chlorinated distillation with the purposes of purifying germanium. Several highlights are summarized as follows: (i) Separation principle and reaction mechanism were discussed to understand this integrated process. (ii) Optimum designs and product analysis were developed to guide industrial recycling. The appropriate parameters for vacuum reduction process on the basis of response surface methodology (RSM) were 920.53°C and 259.63Pa, with 16.64wt.% reductant, and for the chlorinated distillation process, adding 8mol/l HCl and L/S 7, 8wt.% MnO 2 . The global recovery rate of germanium was 83.48±0.36% for the integrated process. (iii) This process overcomes the shortages of traditional process and shows its efficiency and environmental performance. It is significant in accordance with the "Reduce, Reuse and Recycle Principle" for solid waste and further provides a new opportunity for germanium recovery from waste by environment-friendly way. Copyright © 2016. Published by Elsevier B.V.

Germanium layers grown by zone thermal crystallization from a discrete liquid source

NASA Astrophysics Data System (ADS)

Yatsenko, A. N.; Chebotarev, S. N.; Lozovskii, V. N.; Mohamed, A. A. A.; Erimeev, G. A.; Goncharova, L. M.; Varnavskaya, A. A.

2017-11-01

It is proposed and investigated a method for growing thin uniform germanium layers onto large silicon substrates. The technique uses the hexagonally arranged local sources filled with liquid germanium. Germanium evaporates on very close substrate and in these conditions the residual gases vapor pressure highly reduces. It is shown that to achieve uniformity of the deposited layer better than 97% the critical thickness of the vacuum zone must be equal to l cr = 1.2 mm for a hexagonal arranged system of round local sources with the radius of r = 0.75 mm and the distance between the sources of h = 0.5 mm.

[Exposure to nitrogen dioxide and respiratory health at 2 years in the INMA-Valencia cohort].

PubMed

Gutiérrez Oyarce, Alejandra; Ferrero, Amparo; Estarlich, Marisa; Esplugues, Ana; Iñiguez, Carmen; Ballester, Ferran

2017-07-25

To analyze the association between exposure to nitrogen dioxide (NO 2 ) during pregnancy and the postnatal period up to the age of 2 years old and the incidence of respiratory problems in children from the INMA-Valencia cohort. The study population included 624 children from the INMA-Valencia cohort. Individual exposure to NO 2 was estimated in different environments outside the home during pregnancy and up to the age of 2 using empirical measurement and data from geo-statistical methods. Respiratory symptoms were obtained from a questionnaire applied at the age of two. The association between NO 2 exposure and respiratory symptoms was performed using multivariate logistic regression. The cumulative incidence was 16.3% for persistent cough, 34.9% for wheezing and 27.6% for lower respiratory tract infections. No association was found between respiratory symptoms and exposure to NO 2 in any of the children. However an association between NO 2 exposure and persistent cough was found at two years of life in the children with a parental history of allergy. NO 2 exposure would lead to persistent cough in children with a parental history of allergies. Copyright © 2017 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.

A New Global Anthropogenic SO2 Emission Inventory for the Last Decade: A Mosaic of Satellite-derived and Bottom-up Emissions

NASA Astrophysics Data System (ADS)

Liu, F.; Joiner, J.; Choi, S.; Krotkov, N. A.; Li, C.; Fioletov, V. E.; McLinden, C. A.

2017-12-01

Sulfur dioxide (SO2) measurements from the Ozone Monitoring Instrument (OMI) satellite sensor have been used to detect emissions from large point sources using an innovative estimation technique. Emissions from about 500 sources have been quantified individually based on OMI observations, accounting for about a half of total reported anthropogenic SO2 emissions. We developed a new emission inventory, OMI-HTAP, by combining these OMI-based emission estimates and the conventional bottom-up inventory. OMI-HTAP includes OMI-based estimates for over 400 point sources and is gap-filled with the emission grid map of the latest available global bottom-up emission inventory (HTAP v2.2) for the rest of sources. We have evaluated the OMI-HTAP inventory by performing simulations with the Goddard Earth Observing System version 5 (GEOS-5) model. The GEOS-5 simulated SO2 concentrations driven by both the HTAP and the OMI-HTAP inventory were compared against in-situ and satellite measurements. Results show that the OMI-HTAP inventory improves the model agreement with observations, in particular over the US, India and the Middle East. Additionally, simulations with the OMI-HTAP inventory capture the major trends of anthropogenic SO2 emissions over the world and highlight the influence of missing sources in the bottom-up inventory.

Dynamic structural colour using vanadium dioxide thin films

NASA Astrophysics Data System (ADS)

Wilson, K.; Marocico, C. A.; Bradley, A. L.

2018-06-01

A thin film stack consisting of layers of indium tin oxide (ITO) with an intermediate vanadium oxide (VO2) layer on an optically thick silver film has been investigated for dynamic structural colour. The structure benefits from the phase change properties of VO2. Compared with other phase change materials, such as germanium antimony telluride (GST), VO2 can be offered as a lower power consumption alternative. It has been overlooked in the visible spectral range due to its smaller refractive index change below 700 nm. We demonstrate that the sensitivity of the visible reflectance spectrum to the change in phase of a 30 nm VO2 layer is increased after it is incorporated in a thin film stack, with performance comparable to other phase change materials. The extent to which dynamic tuning of the reflectance spectra of ITO–VO2–ITO–Ag thin film stacks can be exploited for colour switching is reported, with approximately 25% change in reflectance demonstrated at 550 nm. Inclusion of a top ITO layer is also shown to improve the chromaticity change on phase transition.

Germanium and Tin Based Anode Materials for Lithium-Ion Batteries

NASA Astrophysics Data System (ADS)

Ji, Dongsheng

The discovery of safe anode materials with high energy density for lithium-ion batteries has always been a significant topic. Group IV elements have been under intensive study for their high capability of alloying with lithium. Batteries with graphite and tin based anode material have already been applied in cell phones and vehicles. In order to apply group IV elements, their dramatic volume change during lithiation and delithiation processes is the key point to work on. Reducing the particle size is the most common method to buffer the volume expansion. This strategy has been applied on both germanium and tin based materials. Germanium based anode material has been made by two different synthesis methods. The amorphous Ge-C-Ti composite material was made by ball milling method and performed much better than other germanium alloy including Ge-Mg, Ge-Fe and Ge-Fe.Germanium sphere nano particles with diameter of around 50 nm have been made by solution method. After ball milled with graphite, the resulted product performed stable capacity over 500 mAh˙g-1 for more than 20 cycles. Ball milled graphite in the composite plays an important role of buffering volume change and stabilizing germanium. Sn-Fe alloy is one of the feasible solutions to stabilize tin. Sn 2Fe-C composite has been made by ball milling method. After optimizations of the ratio of precursors, reaction time, milling balls and electrolyte additives, the electrochemistry performance was improved. The anode performed 420 mAh˙ -1 at 1.0 mA/cm2 and maintained its structure after cycling at 2.0 mA/cm2. At 0.3 mA/cm2 cycling rate, the anode performed 978 mAh/cm3 after 500 cycles, which still exceeds the theoretical capacity of graphite.

Comparison of ultrasonic-assisted and regular leaching of germanium from by-product of zinc metallurgy.

PubMed

Zhang, Libo; Guo, Wenqian; Peng, Jinhui; Li, Jing; Lin, Guo; Yu, Xia

2016-07-01

A major source of germanium recovery and also the source of this research is the by-product of lead and zinc metallurgical process. The primary purpose of the research is to investigate the effects of ultrasonic assisted and regular methods on the leaching yield of germanium from roasted slag containing germanium. In the study, the HCl-CaCl2 mixed solution is adopted as the reacting system and the Ca(ClO)2 used as the oxidant. Through six single factor (leaching time, temperature, amount of Ca(ClO)2, acid concentration, concentration of CaCl2 solution, ultrasonic power) experiments and the comparison of the two methods, it is found the optimum collective of germanium for ultrasonic-assisted method is obtained at temperature 80 °C for a leaching duration of 40 min. The optimum concentration for hydrochloric acid, CaCl2 and oxidizing agent are identified to be 3.5 mol/L, 150 g/L and 58.33 g/L, respectively. In addition, 700 W is the best ultrasonic power and an over-high power is adverse in the leaching process. Under the optimum condition, the recovery of germanium could reach up to 92.7%. While, the optimum leaching condition for regular leaching method is same to ultrasonic-assisted method, except regular method consume 100 min and the leaching rate of Ge 88.35% is lower about 4.35%. All in all, the experiment manifests that the leaching time can be reduced by as much as 60% and the leaching rate of Ge can be increased by 3-5% with the application of ultrasonic tool, which is mainly thanks to the mechanical action of ultrasonic. Copyright © 2015 Elsevier B.V. All rights reserved.

Neutron-transmutation-doped germanium bolometers

NASA Technical Reports Server (NTRS)

Palaio, N. P.; Rodder, M.; Haller, E. E.; Kreysa, E.

1983-01-01

Six slices of ultra-pure germanium were irradiated with thermal neutron fluences between 7.5 x 10 to the 16th and 1.88 x 10 to the 18th per sq cm. After thermal annealing the resistivity was measured down to low temperatures (less than 4.2 K) and found to follow the relationship rho = rho sub 0 exp(Delta/T) in the hopping conduction regime. Also, several junction FETs were tested for noise performance at room temperature and in an insulating housing in a 4.2 K cryostat. These FETs will be used as first stage amplifiers for neutron-transmutation-doped germanium bolometers.

Bottom-up assembly of metallic germanium

NASA Astrophysics Data System (ADS)

Scappucci, Giordano; Klesse, Wolfgang M.; Yeoh, Lareine A.; Carter, Damien J.; Warschkow, Oliver; Marks, Nigel A.; Jaeger, David L.; Capellini, Giovanni; Simmons, Michelle Y.; Hamilton, Alexander R.

2015-08-01

Extending chip performance beyond current limits of miniaturisation requires new materials and functionalities that integrate well with the silicon platform. Germanium fits these requirements and has been proposed as a high-mobility channel material, a light emitting medium in silicon-integrated lasers, and a plasmonic conductor for bio-sensing. Common to these diverse applications is the need for homogeneous, high electron densities in three-dimensions (3D). Here we use a bottom-up approach to demonstrate the 3D assembly of atomically sharp doping profiles in germanium by a repeated stacking of two-dimensional (2D) high-density phosphorus layers. This produces high-density (1019 to 1020 cm-3) low-resistivity (10-4Ω · cm) metallic germanium of precisely defined thickness, beyond the capabilities of diffusion-based doping technologies. We demonstrate that free electrons from distinct 2D dopant layers coalesce into a homogeneous 3D conductor using anisotropic quantum interference measurements, atom probe tomography, and density functional theory.

Caractérisation par résonance paramagnétique électronique (RPE) de quartz naturels issus de différentes sources

NASA Astrophysics Data System (ADS)

Duttine, Mathieu; Villeneuve, Gérard; Bechtel, Françoise; Demazeau, Gérard

2002-10-01

Natural quartz crystals coming from Madagascar, Angola, Brazil, and Spain were studied by EPR after β irradiation in order to characterise the paramagnetic centres due to impurities, and examine in which way their relative proportion could constitute a useful criterion for origin researches. In all our samples, EPR experiments revealed germanium centres [GeO 4/M +]° with M = Li or Na, aluminium ones [AlO 4/h]° and two titanium centres ([TiO 4/H +]° and [TiO 4/M +]°) also appeared, except for samples coming from Spain. The comparison of the relative concentrations of paramagnetic species led us on to draw diagrams that allowed distinguishing the origins of the studied samples using only EPR spectra. To cite this article: M. Duttine et al., C. R. Geoscience 334 (2002) 949-955.

Oxygen Tuned Local Structure and Phase-Change Performance of Germanium Telluride.

PubMed

Zhou, Xilin; Du, Yonghua; Behera, Jitendra K; Wu, Liangcai; Song, Zhitang; Simpson, Robert E

2016-08-10

The effect of oxygen on the local structure of Ge atoms in GeTe-O materials has been investigated. Oxygen leads to a significant modification to the vibrational modes of Ge octahedra, which results from a decrease in its coordination. We find that a defective octahedral Ge network is the crucial fingerprint for rapid and reversible structural transitions in GeTe-based phase change materials. The appearance of oxide Raman modes confirms phase separation into GeO and TeO at high level O doping. Counterintuitively, despite the increase in crystallization temperature of oxygen doped GeTe-O phase change materials, when GeTe-O materials are used in electrical phase change memory cells, the electrical switching energy is lower than the pure GeTe material. This switching energy reduction is ascribed to the smaller change in volume, and therefore smaller enthalpy change, for the oxygen doped GeTe materials.

Insight into unusual impurity absorbability of GeO(2) in GeO(2)∕Ge stacks.

PubMed

Ogawa, Shingo; Suda, Taichi; Yamamoto, Takashi; Kutsuki, Katsuhiro; Hideshima, Iori; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

2011-10-03

Adsorbed species and its diffusion behaviors in GeO(2)∕Ge stacks, which are future alternative metal-oxide-semiconductor (MOS) materials, have been investigated using various physical analyses. We clarified that GeO(2) rapidly absorbs moisture in air just after its exposure. After the absorbed moisture in GeO(2) reaches a certain limit, the GeO(2) starts to absorb some organic molecules, which is accompanied by a structural change in GeO(2) to form a partial carbonate or hydroxide. We also found that the hydrogen distribution in GeO(2) shows intrinsic characteristics, indicative of different diffusion behaviors at the surface and at the GeO(2)∕Ge interface. Because the impurity absorbability of GeO(2) has a great influence on the electrical properties in Ge-MOS devices, these results provide valuable information in realizing high quality GeO(2)∕Ge stacks for the actual use of Ge-MOS technologies.

Variability in impact of air pollution on subjective well-being

NASA Astrophysics Data System (ADS)

Du, Guodong; Shin, Kong Joo; Managi, Shunsuke

2018-06-01

This paper examines the impact of variability in impact of air pollution on life satisfaction (LS). Previous studies have shown robust negative impact of air pollution on subjective well-being (SWB). However, empirical studies that consider variability in air pollution effects through comparative city study are limited. This study provides comparative evaluation of two major Chinese cities: Beijing and Shanghai. We apply a geo-statistical spatial interpolation technique on pollution data from monitoring sites to estimate the Sulfur Dioxide (SO2), Nitrogen Dioxide (NO2), coarse particles with a diameter between 2.5 and 10 μm (PM10) and fine particles with a diameter of 2.5 μm or less (PM2.5) pollution exposure of respondents of a survey conducted in 2016. The results show that all pollutants have robust negative impacts on LS for Beijing residents, whereas only SO2 and NO2 have significant negative impacts on LS for Shanghai residents; Per unit impact of SO2 is greater in Shanghai, and that of NO2 is greater in Beijing. Beijing and Shanghai residents have almost same monetary valuation for SO2 reduction but Beijing residents place approximately 1.5 times valuation on NO2 reduction compared to Shanghai residents. Moreover, the LS of Beijing residents is sensitive to temporal changes in the pollution level, whereas Shanghai residents are unaffected by such changes.

High-resolution imaging gamma-ray spectroscopy with externally segmented germanium detectors

NASA Technical Reports Server (NTRS)

Callas, J. L.; Mahoney, W. A.; Varnell, L. S.; Wheaton, W. A.

1993-01-01

Externally segmented germanium detectors promise a breakthrough in gamma-ray imaging capabilities while retaining the superb energy resolution of germanium spectrometers. An angular resolution of 0.2 deg becomes practical by combining position-sensitive germanium detectors having a segment thickness of a few millimeters with a one-dimensional coded aperture located about a meter from the detectors. Correspondingly higher angular resolutions are possible with larger separations between the detectors and the coded aperture. Two-dimensional images can be obtained by rotating the instrument. Although the basic concept is similar to optical or X-ray coded-aperture imaging techniques, several complicating effects arise because of the penetrating nature of gamma rays. The complications include partial transmission through the coded aperture elements, Compton scattering in the germanium detectors, and high background count rates. Extensive electron-photon Monte Carlo modeling of a realistic detector/coded-aperture/collimator system has been performed. Results show that these complicating effects can be characterized and accounted for with no significant loss in instrument sensitivity.

Stable Organic Monolayers on Oxide-Free Silicon/Germanium in a Supercritical Medium: A New Route to Molecular Electronics.

PubMed

Puniredd, Sreenivasa Reddy; Jayaraman, Sundaramurthy; Yeong, Sai Hooi; Troadec, Cedric; Srinivasan, M P

2013-05-02

Oxide-free Si and Ge surfaces have been passivated and modified with organic molecules by forming covalent bonds between the surfaces and reactive end groups of linear alkanes and aromatic species using single-step deposition in supercritical carbon dioxide (SCCO2). The process is suitable for large-scale manufacturing due to short processing times, simplicity, and high resistance to oxidation. It also allows the formation of monolayers with varying reactive terminal groups, thus enabling formation of nanostructures engineered at the molecular level. Ballistic electron emission microscopy (BEEM) spectra performed on the organic monolayer on oxide-free silicon capped by a thin gold layer reveals for the first time an increase in transmission of the ballistic current through the interface of up to three times compared to a control device, in contrast to similar studies reported in the literature suggestive of oxide-free passivation in SCCO2. The SCCO2 process combined with the preliminary BEEM results opens up new avenues for interface engineering, leading to molecular electronic devices.

Map of critical raw material deposits in Europe

NASA Astrophysics Data System (ADS)

Guillaume, Bertrand

2016-04-01

Map of critical raw material deposits in Europe Guillaume BERTRAND1, Daniel CASSARD1, Nikolaos ARVANITIDIS2, Gerry STANLEY3 and the EuroGeoSurvey Mineral Resources Expert Group4. 1 - Bureau de Recherches Géologiques et Minières (BRGM), Georesources Divison, 3 avenue Claude Guillemin, 45060 Orléans cedex 2, FRANCE. 2 - Sveriges Geologiska Undersökning (SGU), Box 670, SE-751 28, Uppsala, SWEDEN 3 - Geological Survey of Ireland (GSI), Beggars Bush, Haddington Road, Dublin D04 K7X4, IRELAND 4 - EuroGeoSurveys, Rue Joseph II 36-38, 1000 Brussels, BELGIUM The Critical Raw Material (CRM) Deposit Map of Europe, prepared by EuroGeoSurvey's Mineral Resources Expert Group (MREG), shows European mineral deposits from the ProMine Mineral Deposit database containing critical commodities, according to the 2014 list of critical raw materials of the European Commission. EuroGeoSurveys (EGS), The Geological Surveys of Europe, is a not-for-profit organization representing 37 National Geological Surveys and some regional Geological Surveys in Europe. It provides the European Institutions with expert, independent, balanced and practical pan-European advice and information as an aid to problem-solving, policy development, regulatory and programme formulation in areas such as natural resources, energy and geo-hazards. The EGS MREG is actively involved in contributing to policy and strategy-making processes aimed at identifying, characterizing and safeguarding resource potential, especially for critical raw materials through data provision, research, technological development and innovation. The European Union aspires to reducing the import dependency of raw materials, especially CRM, that are essential to Europe's industries. In this respect, mineral resource information, data sharing and networking by European Geological Surveys is crucial. The Strategic Implementation Plan of the European Innovation Partnership on Raw Materials highlights the need for establishing and maintaining a common interoperable EU Geological Knowledge Base. Such a Knowledge Base will support exploration for indigenous mineral resources and strengthen policy and decision making. In 2010, the European Commission identified 14 non energy non-agricultural raw materials as being critical. Criticality is based on both the scarcity of supply and the importance to European industry. This list was updated in 2014 to include 7 new commodities with one being dropped from the original list. The list now comprises: antimony, beryllium, borates, chromium, cobalt, coking coal, fluorspar, gallium, germanium, graphite, indium, magnesite, magnesium, niobium, phosphate rock, platinum group metals, light and heavy rare earth elements (separately), silicon metal and tungsten. ProMine was a European Union (EU) co-funded project, which had as its main objective the stimulation of the extractive industry to deliver new products to manufacturing industry. A major deliverable of the project was the ProMine Mineral Deposit (MD) database that contains information related to almost 13,000 mineral deposits in Europe. In order to extract data to be displayed on the CRM map of Europe, the ProMine MD database was queried for all commodities on the EC CRM list which were in the medium to super-large deposit size. Following this, the dataset was circulated to MREG in order to verify, validate and update the list.

Hydrometallurgical recovery of germanium from coal gasification fly ash: pilot plant scale evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arroyo, F.; Fernandez-Pereira, C.; Olivares, J.

2009-04-15

In this article, a hydrometallurgical method for the selective recovery of germanium from fly ash (FA) has been tested at pilot plant scale. The pilot plant flowsheet comprised a first stage of water leaching of FA, and a subsequent selective recovery of the germanium from the leachate by solvent extraction method. The solvent extraction method was based on Ge complexation with catechol in an aqueous solution followed by the extraction of the Ge-catechol complex (Ge(C{sub 6}H{sub 4}O{sub 2}){sub 3}{sup 2-}) with an extracting organic reagent (trioctylamine) diluted in an organic solvent (kerosene), followed by the subsequent stripping of the organicmore » extract. The process has been tested on a FA generated in an integrated gasification with combined cycle (IGCC) process. The paper describes the designed 5 kg/h pilot plant and the tests performed on it. Under the operational conditions tested, approximately 50% of germanium could be recovered from FA after a water extraction at room temperature. Regarding the solvent extraction method, the best operational conditions for obtaining a concentrated germanium-bearing solution practically free of impurities were as follows: extraction time equal to 20 min; aqueous phase/organic phase volumetric ratio equal to 5; stripping with 1 M NaOH, stripping time equal to 30 min, and stripping phase/organic phase volumetric ratio equal to 5. 95% of germanium were recovered from water leachates using those conditions.« less

Kinetic study of GeO disproportionation into a GeO{sub 2}/Ge system using x-ray photoelectron spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Shengkai; Department of Materials Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656; CREST, Japan Science and Technology Agency

2012-08-06

GeO disproportionation into GeO{sub 2} and Ge is studied through x-ray photoelectron spectroscopy. Direct evidence for the reaction 2GeO {yields} GeO{sub 2} + Ge after annealing in ultra-high vacuum is presented. Activation energy for GeO disproportionation is found to be about 0.7 {+-} 0.2 eV through kinetic and thermodynamic calculations. A kinetic model of GeO disproportionation is established by considering oxygen transfer in the GeO network. The relationship between GeO disproportionation and GeO desorption induced by GeO{sub 2}/Ge interfacial reaction is discussed, and the apparent contradiction between GeO desorption via interfacial redox reaction and GeO disproportionation into Ge and GeO{submore » 2} is explained by considering the oxygen vacancy.« less

Bottom-up assembly of metallic germanium.

PubMed

Scappucci, Giordano; Klesse, Wolfgang M; Yeoh, LaReine A; Carter, Damien J; Warschkow, Oliver; Marks, Nigel A; Jaeger, David L; Capellini, Giovanni; Simmons, Michelle Y; Hamilton, Alexander R

2015-08-10

Extending chip performance beyond current limits of miniaturisation requires new materials and functionalities that integrate well with the silicon platform. Germanium fits these requirements and has been proposed as a high-mobility channel material, a light emitting medium in silicon-integrated lasers, and a plasmonic conductor for bio-sensing. Common to these diverse applications is the need for homogeneous, high electron densities in three-dimensions (3D). Here we use a bottom-up approach to demonstrate the 3D assembly of atomically sharp doping profiles in germanium by a repeated stacking of two-dimensional (2D) high-density phosphorus layers. This produces high-density (10(19) to 10(20) cm(-3)) low-resistivity (10(-4)Ω · cm) metallic germanium of precisely defined thickness, beyond the capabilities of diffusion-based doping technologies. We demonstrate that free electrons from distinct 2D dopant layers coalesce into a homogeneous 3D conductor using anisotropic quantum interference measurements, atom probe tomography, and density functional theory.

Front End Spectroscopy ASIC for Germanium Detectors

NASA Astrophysics Data System (ADS)

Wulf, Eric

Large-area, tracking, semiconductor detectors with excellent spatial and spectral resolution enable exciting new access to soft (0.2-5 MeV) gamma-ray astrophysics. The improvements from semiconductor tracking detectors come with the burden of high density of strips and/or pixels that require high-density, low-power, spectroscopy quality readout electronics. CMOS ASIC technologies are a natural fit to this requirement and have led to high-quality readout systems for all current semiconducting tracking detectors except for germanium detectors. The Compton Spectrometer and Imager (COSI), formerly NCT, at University of California Berkeley and the Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) at Goddard Space Flight Center utilize germanium cross-strip detectors and are on the forefront of NASA's Compton telescope research with funded missions of long duration balloon flights. The development of a readout ASIC for germanium detectors would allow COSI to replace their discrete electronics readout and would enable the proposed Gamma-Ray Explorer (GRX) mission utilizing germanium strip-detectors. We propose a 3-year program to develop and test a germanium readout ASIC to TRL 5 and to integrate the ASIC readout onto a COSI detector allowing a TRL 6 demonstration for the following COSI balloon flight. Our group at NRL led a program, sponsored by another government agency, to produce and integrate a cross-strip silicon detector ASIC, designed and fabricated by Dr. De Geronimo at Brookhaven National Laboratory. The ASIC was designed to handle the large (>30 pF) capacitance of three 10 cm^2 detectors daisy-chained together. The front-end preamplifier, selectable inverter, shaping times, and gains make this ASIC compatible with a germanium cross-strip detector as well. We therefore have the opportunity and expertise to leverage the previous investment in the silicon ASIC for a new mission. A germanium strip detector ASIC will also require precise timing of the signals at the anode and cathode of the device to allow the depth of the interaction within the crystal to be determined. Dr. De Geronimo has developed similar timing circuits for CZT detector ASICs. Furthermore, the timing circuitry of the ASIC is at the very end of the analog section, simplifying and mitigating risks in the redesign. In the first year, we propose to tweak the gain settings and to add timing to the silicon ASIC to match the requirements of a germanium detector. The design specifications of the ASIC will include advice from our collaborators Dr. Boggs from COSI and Dr. Shih from GRIPS. By using a master ASIC designer to integrate his proven front-end and back-end with only minor modifications, we are maximizing the probability of success. NRL has a commercial cross-strip germanium detector with 30 pF of capacitance per strip, including the flex circuit from the detector to the outside of the cryostat. The COSI and GRIPS detectors have a similar capacitance per strip on the outside of their mechanically cooled cryostat. The second year of the program will be devoted to testing the newly fabricated germanium cross-strip ASIC with the NRL germanium detector. At the end of the second year, NASA will have a TRL 5 ASIC for germanium detectors, allowing future missions, including COSI, GRX, and GRIPS, to operate within their thermal and electrical envelopes. At the end of the third year, a detector on COSI will be instrumented with the new ASIC allowing for a TRL 6 demonstration during the following COSI balloon flight.

Fabrication and characterization of active nanostructures

NASA Astrophysics Data System (ADS)

Opondo, Noah F.

Three different nanostructure active devices have been designed, fabricated and characterized. Junctionless transistors based on highly-doped silicon nanowires fabricated using a bottom-up fabrication approach are first discussed. The fabrication avoids the ion implantation step since silicon nanowires are doped in-situ during growth. Germanium junctionless transistors fabricated with a top down approach starting from a germanium on insulator substrate and using a gate stack of high-k dielectrics and GeO2 are also presented. The levels and origin of low-frequency noise in junctionless transistor devices fabricated from silicon nanowires and also from GeOI devices are reported. Low-frequency noise is an indicator of the quality of the material, hence its characterization can reveal the quality and perhaps reliability of fabricated transistors. A novel method based on low-frequency noise measurement to envisage trap density in the semiconductor bandgap near the semiconductor/oxide interface of nanoscale silicon junctionless transistors (JLTs) is presented. Low-frequency noise characterization of JLTs biased in saturation is conducted at different gate biases. The noise spectrum indicates either a Lorentzian or 1/f. A simple analysis of the low-frequency noise data leads to the density of traps and their energy within the semiconductor bandgap. The level of noise in silicon JLT devices is lower than reported values on transistors fabricated using a top-down approach. This noise level can be significantly improved by improving the quality of dielectric and the channel interface. A micro-vacuum electron device based on silicon field emitters for cold cathode emission is also presented. The presented work utilizes vertical Si nanowires fabricated by means of self-assembly, standard lithography and etching techniques as field emitters in this dissertation. To obtain a high nanowire density, hence a high current density, a simple and inexpensive Langmuir Blodgett technique to deposit silica nanoparticles as a mask to etch Si is adopted. Fabrication and characterization of a metal-gated microtriode with a high current density and low operating voltage are presented.

Effect of ion-plated films of germanium and silicon on friction, wear, and oxidation of 52100 bearing steel

NASA Technical Reports Server (NTRS)

Buckley, D. H.; Spalvins, T.

1977-01-01

Friction and wear experiments were conducted with ion plated films of germanium and silicon on the surface of 52100 bearing steel both dry and in the presence of mineral oil. Both silicon and germanium were found to reduce wear, with germanium being more effective than silicon. An optimum film thickness of germanium for minimum wear without surface crack formation was found to be approximately 400 nanometers (4000 A). The presence of silicon and germanium on the 52100 bearing steel surface improved resistance to oxidation.

Deformation potentials for band-to-band tunneling in silicon and germanium from first principles

NASA Astrophysics Data System (ADS)

Vandenberghe, William G.; Fischetti, Massimo V.

2015-01-01

The deformation potentials for phonon-assisted band-to-band tunneling (BTBT) in silicon and germanium are calculated using a plane-wave density functional theory code. Using hybrid functionals, we obtain: DTA = 4.1 × 108 eV/cm, DTO = 1.2 × 109 eV/cm, and DLO = 2.2 × 109 eV/cm for BTBT in silicon and DTA = 7.8 × 108 eV/cm and DLO = 1.3 × 109 eV/cm for BTBT in germanium. These values agree with experimentally measured values and we explain why in diodes, the TA/TO phonon-assisted BTBT dominates over LO phonon-assisted BTBT despite the larger deformation potential for the latter. We also explain why LO phonon-assisted BTBT can nevertheless dominate in many practical applications.

Multidimensional Germanium-Based Materials as Anodes for Lithium-Ion Batteries.

PubMed

Qin, Jinwen; Cao, Minhua

2016-04-20

Metallic germanium is an ideal anode for lithium-ion batteries (LIBs), owing to its high theoretical capacity (1624 mA h g(-1) ) and low operating voltage. Herein, we highlight recent advances in the development of Ge-based anodes in LIBs, although improvements in their coulombic efficiency (CE), capacity retention, and rate performance are still required. One of the major concerns facing the development of Ge anodes is the controlled formation of microstructures. In this Focus Review, we summarize Ge-based materials with different structural dimensions, that is, zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), three-dimensional (3D), and even monolithic and macroscale structures. Moreover, the design of Ge-based oxide materials, as an effective route for achieving higher Li-storage capacities and cycling performance, is also discussed. Finally, we briefly summarize new types of Ge-based materials, such as ternary germanium oxides, germanium sulfides, and germanium phosphides, and predict that they will bring about a reformation in the field of LIBs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

ISCCP-D2like-GEO Ed3A

Atmospheric Science Data Center

2018-05-16

ISCCP-D2like-GEO Ed3A Project Title:  CERES Discipline:  ... Order Data Guide Documents:  GEO Description/Abstract Detailed CERES ISCCP-D2like Product ... Data Products Catalog:  DPC_ISCCP-D2like-GEO_R5V3  (PDF) Readme Files:  Readme GEO R5-987 ...

High Precision Metal Thin Film Liftoff Technique

NASA Technical Reports Server (NTRS)

Brown, Ari D. (Inventor); Patel, Amil A. (Inventor)

2015-01-01

A metal film liftoff process includes applying a polymer layer onto a silicon substrate, applying a germanium layer over the polymer layer to create a bilayer lift off mask, applying a patterned photoresist layer over the germanium layer, removing an exposed portion of the germanium layer, removing the photoresist layer and a portion of the polymer layer to expose a portion of the substrate and create an overhanging structure of the germanium layer, depositing a metal film over the exposed portion of the substrate and the germanium layer, and removing the polymer and germanium layers along with the overlaying metal film.

Red-luminescence band: A tool for the quality assessment of germanium and silicon nanocrystals

NASA Astrophysics Data System (ADS)

Fraj, I.; Favre, L.; David, T.; Abbarchi, M.; Liu, K.; Claude, J. B.; Ronda, A.; Naffouti, M.; Saidi, F.; Hassen, F.; Maaref, H.; Aqua, J. N.; Berbezier, I.

2017-10-01

We present the photoluminescence (PL) emission of Silicon and Germanium nanocrystals (NCs) of different sizes embedded in two different matrices. Formation of the NCs is achieved via solid-state dewetting during annealing in a molecular beam epitaxy ultra-high vacuum system of ultrathin amorphous Si and Ge layers deposited at room temperature on SiO2. During the dewetting process, the bi-dimensional amorphous layers transform into small pseudo-spherical islands whose mean size can be tuned directly with the deposited thickness. The nanocrystals are capped either ex situ by silicon dioxide or in situ by amorphous Silicon. The surface-state dependent emission (typically in the range 1.74 eV-1.79 eV) exhibited higher relative PL quantum yields compared to the emission originating from the band gap transition. This red-PL emission comes from the radiative transitions between a Si band and an interface level. It is mainly ascribed to the NCs and environment features deduced from morphological and structural analyses. Power dependent analysis of the photoluminescence intensity under continuous excitation reveals a conventional power law with an exponent close to 1, in agreement with the type II nature of the emission. We show that Ge-NCs exhibit much lower quantum efficiency than Si-NCs due to non-radiative interface states. Low quantum efficiency is also obtained when NCs have been exposed to air before capping, even if the exposure time is very short. Our results indicate that a reduction of the non-radiative surface states is a key strategy step in producing small NCs with increased PL emission for a variety of applications. The red-PL band is then an effective tool for the quality assessment of NCs based structures.

Crystal growth from the vapor phase experiment MA-085

NASA Technical Reports Server (NTRS)

Wiedemeir, H.; Sadeek, H.; Klaessig, F. C.; Norek, M.

1976-01-01

Three vapor transport experiments on multicomponent systems were performed during the Apollo Soyuz mission to determine the effects of microgravity forces on crystal morphology and mass transport rates. The mixed systems used germanium selenide, tellurium, germanium tetraiodide (transport agent), germanium monosulfide, germanium tetrachloride (transport agent), and argon (inert atmosphere). The materials were enclosed in evacuated sealed ampoules of fused silica and were transported in a temperature gradient of the multipurpose electric furnace onboard the Apollo Soyuz spacecraft. Preliminary evaluation of 2 systems shows improved quality of space grown crystals in terms of growth morphology and bulk perfection. This conclusion is based on a direct comparison of space grown and ground based crystals by means of X-ray diffraction, microscopic, and chemical etching techniques. The observation of greater mass transport rates than predicted for a microgravity environment by existing vapor transport models indicates the existence of nongravity caused transport effects in a reactive solid/gas phase system.

Single-Crystal Germanium Core Optoelectronic Fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ji, Xiaoyu; Page, Ryan L.; Chaudhuri, Subhasis

Synthesis and fabrication of high-quality, small-core single-crystal germanium fibers that are photosensitive at the near-infrared and have low optical losses ≈1 dB cm-1 at 2 μm are reported. These fibers have potential applications in fiber-based spectroscopic imaging, nonlinear optical devices, and photodetection at the telecommunication wavelengths.

Impact of a Regional Drought on Terrestrial Carbon Fluxes and Atmospheric Carbon: Results from a Coupled Carbon Cycle Model

NASA Technical Reports Server (NTRS)

Lee, Eunjee; Koster, Randal D.; Ott, Lesley E.; Weir, Brad; Mahanama, Sarith; Chang, Yehui; Zeng, Fan-Wei

2017-01-01

Understanding the underlying processes that control the carbon cycle is key to predicting future global change. Much of the uncertainty in the magnitude and variability of the atmospheric carbon dioxide (CO2) stems from uncertainty in terrestrial carbon fluxes, and the relative impacts of temperature and moisture variations on regional and global scales are poorly understood. Here we investigate the impact of a regional drought on terrestrial carbon fluxes and CO2 mixing ratios over North America using the NASA Goddard Earth Observing System (GEOS) Model. Results show a sequence of changes in carbon fluxes and atmospheric CO2, induced by the drought. The relative contributions of meteorological changes to the neighboring carbon dynamics are also presented. The coupled modeling approach allows a direct quantification of the impact of the regional drought on local and proximate carbon exchange at the land surface via the carbon-water feedback processes.

Mineral resource of the month: germanium

USGS Publications Warehouse

Guberman, David

2010-01-01

The article provides information on germanium, an element with electrical properties between those of a metal and an insulator. Applications of germanium include its use as a component of the glass in fiber-optic cable, in infrared optics devices and as a semiconductor and substrate used in electronic and solar applications. Germanium was first isolated by German chemist Clemens Winkler in 1886 and was named after Winkler's native country. In 2008, the leading sources of primary germanium from coal or zinc include Canada, China and Russia.

Paramagnetic defects and charge trapping behavior of ZrO2 films deposited on germanium by plasma-enhanced CVD

NASA Astrophysics Data System (ADS)

Mahata, C.; Bera, M. K.; Bose, P. K.; Maiti, C. K.

2009-02-01

Internal photoemission and magnetic resonance studies have been performed to investigate the charge trapping behavior and chemical nature of defects in ultrathin (~14 nm) high-k ZrO2 dielectric films deposited on p-Ge (1 0 0) substrates at low temperature (<200 °C) by plasma-enhanced chemical vapor deposition (PECVD) in a microwave (700 W, 2.45 GHz) plasma at a pressure of ~65 Pa. Both the band and defect-related electron states have been characterized using electron paramagnetic resonance, internal photoemission, capacitance-voltage and current-voltage measurements under UV illumination. Capacitance-voltage and photocurrent-voltage measurements were used to determine the centroid of oxide charge within the high-k gate stack. The observed shifts in photocurrent response of the Al/ZrO2/GeO2/p-Ge metal-insulator-semiconductor (MIS) capacitors indicate the location of the centroids to be within the ZrO2 dielectric near to the gate electrode. Moreover, the measured flat band voltage and photocurrent shifts also indicate a large density of traps in the dielectric. The impact of plasma nitridation on the interfacial quality of the oxides has been investigated. Different N sources, such as NO and NH3, have been used for nitrogen engineering. Oxynitride samples show a lower defect density and trapping over the non-nitrided samples. The charge trapping and detrapping properties of MIS capacitors under stressing in constant current and voltage modes have been investigated in detail.

Structural studies of gels and gel-glasses in the SiO2-GeO2 system using vibrational spectroscopy

NASA Technical Reports Server (NTRS)

Mukherjee, Shyama P.; Sharma, Shiv K.

1986-01-01

GeO2 gel and gels in the SiO2-GeO2 system synthesized by the hydrolytic polycondensation of metal alkoxides have been studied by infrared and Raman spectroscopic techniques. The molecular structures, hydroxyl contents, and crystallinity of gels and gel-glasses in relation to the thermal history and GeO2 concentration were investigated. The binary compositions having up to 70 mol percent GeO2 were examined.

Remote interfacial dipole scattering and electron mobility degradation in Ge field-effect transistors with GeO x /Al2O3 gate dielectrics

NASA Astrophysics Data System (ADS)

Wang, Xiaolei; Xiang, Jinjuan; Wang, Shengkai; Wang, Wenwu; Zhao, Chao; Ye, Tianchun; Xiong, Yuhua; Zhang, Jing

2016-06-01

Remote Coulomb scattering (RCS) on electron mobility degradation is investigated experimentally in Ge-based metal-oxide-semiconductor field-effect-transistors (MOSFETs) with GeO x /Al2O3 gate stacks. It is found that the mobility increases with greater GeO x thickness (7.8-20.8 Å). The physical origin of this mobility dependence on GeO x thickness is explored. The following factors are excluded: Coulomb scattering due to interfacial traps at GeO x /Ge, phonon scattering, and surface roughness scattering. Therefore, the RCS from charges in gate stacks is studied. The charge distributions in GeO x /Al2O3 gate stacks are evaluated experimentally. The bulk charges in Al2O3 and GeO x are found to be negligible. The density of the interfacial charge is  +3.2  ×  1012 cm-2 at the GeO x /Ge interface and  -2.3  ×  1012 cm-2 at the Al2O3/GeO x interface. The electric dipole at the Al2O3/GeO x interface is found to be  +0.15 V, which corresponds to an areal charge density of 1.9  ×  1013 cm-2. The origin of this mobility dependence on GeO x thickness is attributed to the RCS due to the electric dipole at the Al2O3/GeO x interface. This remote dipole scattering is found to play a significant role in mobility degradation. The discovery of this new scattering mechanism indicates that the engineering of the Al2O3/GeO x interface is key for mobility enhancement and device performance improvement. These results are helpful for understanding and engineering Ge mobility enhancement.

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... primary and secondary germanium and gallium subcategory. 421.180 Section 421.180 Protection of Environment... POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180 Applicability: Description of the primary and secondary germanium and gallium subcategory. The provisions of this subpart are...

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... primary and secondary germanium and gallium subcategory. 421.180 Section 421.180 Protection of Environment... POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180 Applicability: Description of the primary and secondary germanium and gallium subcategory. The provisions of this subpart are...

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... primary and secondary germanium and gallium subcategory. 421.180 Section 421.180 Protection of Environment... POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180 Applicability: Description of the primary and secondary germanium and gallium subcategory. The provisions of this subpart are...

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... primary and secondary germanium and gallium subcategory. 421.180 Section 421.180 Protection of Environment... POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180 Applicability: Description of the primary and secondary germanium and gallium subcategory. The provisions of this subpart are...

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... primary and secondary germanium and gallium subcategory. 421.180 Section 421.180 Protection of Environment... POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180 Applicability: Description of the primary and secondary germanium and gallium subcategory. The provisions of this subpart are...

Tunable conductivity in mesoporous germanium

NASA Astrophysics Data System (ADS)

Beattie, Meghan N.; Bioud, Youcef A.; Hobson, David G.; Boucherif, Abderraouf; Valdivia, Christopher E.; Drouin, Dominique; Arès, Richard; Hinzer, Karin

2018-05-01

Germanium-based nanostructures have attracted increasing attention due to favourable electrical and optical properties, which are tunable on the nanoscale. High densities of germanium nanocrystals are synthesized via electrochemical etching, making porous germanium an appealing nanostructured material for a variety of applications. In this work, we have demonstrated highly tunable electrical conductivity in mesoporous germanium layers by conducting a systematic study varying crystallite size using thermal annealing, with experimental conductivities ranging from 0.6 to 33 (×10‑3) Ω‑1 cm‑1. The conductivity of as-prepared mesoporous germanium with 70% porosity and crystallite size between 4 and 10 nm is shown to be ∼0.9 × 10‑3 Ω‑1 cm‑1, 5 orders of magnitude smaller than that of bulk p-type germanium. Thermal annealing for 10 min at 400 °C further reduced the conductivity; however, annealing at 450 °C caused a morphological transformation from columnar crystallites to interconnecting granular crystallites and an increase in conductivity by two orders of magnitude relative to as-prepared mesoporous germanium caused by reduced influence of surface states. We developed an electrostatic model relating the carrier concentration and mobility of p-type mesoporous germanium to the nanoscale morphology. Correlation within an order of magnitude was found between modelled and experimental conductivities, limited by variation in sample uniformity and uncertainty in void size and fraction after annealing. Furthermore, theoretical results suggest that mesoporous germanium conductivity could be tuned over four orders of magnitude, leading to optimized hybrid devices.

Gallium-doped germanium, evaluation of photoconductors, part 1

NASA Technical Reports Server (NTRS)

Moore, W. J.

1979-01-01

Gallium-doped germanium far infrared detectors were evaluated at low temperatures and low background simulating the space environment. Signal and noise characteristics were determined for detector temperatures in the 2K to 4K range. Optimum performance occurs at about 2.5K for all devices tested. The minimum average NEP in the 40-130 micron region was found to be approximately 4 x 10 to the minus 17th power watt Hz(-1/2) at a frequency of 1 Hz.

Divacancy-hydrogen complexes in dislocation-free high-purity germanium. [Annealing, Hall effect, steady-state concentration energy dependence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haller, E.E.; Hubbard, G.S.; Hansen, W.L.

1976-09-01

A defect center with a single acceptor level at E/sub v/ + 0.08 eV appears in H/sub 2/-grown dislocation-free high-purity germanium. Its concentration changes reversibly upon annealing up to 650 K. By means of Hall-effect and conductivity measurements over a large temperature range the temperature dependence of the steady-state concentration between 450 and 720 K as well as the transients following changes in temperature were determined. The observed acceptor level is attributed to the divacancy-hydrogen complex V/sub 2/H. The complex reacts with hydrogen, dissolved in the Ge lattice or stored in traps, according to V/sub 2/H + H reversible V/submore » 2/H/sub 2/. An energy level associated with the divacancy-dihydrogen complex was not observed. These results are in good agreement with the idea that hydrogen in germanium forms a ''very deep donor'' (i.e., the energy level lies inside the valence band).« less

TID Simulation of Advanced CMOS Devices for Space Applications

NASA Astrophysics Data System (ADS)

Sajid, Muhammad

2016-07-01

This paper focuses on Total Ionizing Dose (TID) effects caused by accumulation of charges at silicon dioxide, substrate/silicon dioxide interface, Shallow Trench Isolation (STI) for scaled CMOS bulk devices as well as at Buried Oxide (BOX) layer in devices based on Silicon-On-Insulator (SOI) technology to be operated in space radiation environment. The radiation induced leakage current and corresponding density/concentration electrons in leakage current path was presented/depicted for 180nm, 130nm and 65nm NMOS, PMOS transistors based on CMOS bulk as well as SOI process technologies on-board LEO and GEO satellites. On the basis of simulation results, the TID robustness analysis for advanced deep sub-micron technologies was accomplished up to 500 Krad. The correlation between the impact of technology scaling and magnitude of leakage current with corresponding total dose was established utilizing Visual TCAD Genius program.

(Zn, Mg)2GeO4:Mn2+ submicrorods as promising green phosphors for field emission displays: hydrothermal synthesis and luminescence properties.

PubMed

Shang, Mengmeng; Li, Guogang; Yang, Dongmei; Kang, Xiaojiao; Peng, Chong; Cheng, Ziyong; Lin, Jun

2011-10-07

(Zn(1-x-y)Mg(y))(2)GeO(4): xMn(2+) (y = 0-0.30; x = 0-0.035) phosphors with uniform submicrorod morphology were synthesized through a facile hydrothermal process. X-Ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence (PL), and cathodoluminescence (CL) spectroscopy were utilized to characterize the samples. SEM and TEM images indicate that Zn(2)GeO(4):Mn(2+) samples consist of submicrorods with lengths around 1-2 μm and diameters around 200-250 nm, respectively. The possible formation mechanism for Zn(2)GeO(4) submicrorods has been presented. PL and CL spectroscopic characterizations show that pure Zn(2)GeO(4) sample shows a blue emission due to defects, while Zn(2)GeO(4):Mn(2+) phosphors exhibit a green emission corresponding to the characteristic transition of Mn(2+) ((4)T(1)→(6)A(1)) under the excitation of UV and low-voltage electron beam. Compared with Zn(2)GeO(4):Mn(2+) sample prepared by solid-state reaction, Zn(2)GeO(4):Mn(2+) phosphors obtained by hydrothermal process followed by high temperature annealing show better luminescence properties. In addition, codoping Mg(2+) ions into the lattice to substitute for Zn(2+) ions can enhance both the PL and CL intensity of Zn(2)GeO(4):Mn(2+) phosphors. Furthermore, Zn(2)GeO(4):Mn(2+) phosphors exhibit more saturated green emission than the commercial FEDs phosphor ZnO:Zn, and it is expected that these phosphors are promising for application in field-emission displays.

Structure and Stability of GeAu{sub n}, n = 1-10 clusters: A Density Functional Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Priyanka,; Dharamvir, Keya; Sharma, Hitesh

2011-12-12

The structures of Germanium doped gold clusters GeAu{sub n} (n = 1-10) have been investigated using ab initio calculations based on density functional theory (DFT). We have obtained ground state geometries of GeAu{sub n} clusters and have it compared with Silicon doped gold clusters and pure gold clusters. The ground state geometries of the GeAu{sub n} clusters show patterns similar to silicon doped gold clusters except for n = 5, 6 and 9. The introduction of germanium atom increases the binding energy of gold clusters. The binding energy per atom of germanium doped cluster is smaller than the corresponding siliconmore » doped gold cluster. The HUMO-LOMO gap for Au{sub n}Ge clusters have been found to vary between 0.46 eV-2.09 eV. The mullikan charge analysis indicates that charge of order of 0.1e always transfers from germanium atom to gold atom.« less

Bandgap-customizable germanium using lithographically determined biaxial tensile strain for silicon-compatible optoelectronics.

PubMed

Sukhdeo, David S; Nam, Donguk; Kang, Ju-Hyung; Brongersma, Mark L; Saraswat, Krishna C

2015-06-29

Strain engineering has proven to be vital for germanium-based photonics, in particular light emission. However, applying a large permanent biaxial tensile strain to germanium has been a challenge. We present a simple, CMOS-compatible technique to conveniently induce a large, spatially homogenous strain in circular structures patterned within germanium nanomembranes. Our technique works by concentrating and amplifying a pre-existing small strain into a circular region. Biaxial tensile strains as large as 1.11% are observed by Raman spectroscopy and are further confirmed by photoluminescence measurements, which show enhanced and redshifted light emission from the strained germanium. Our technique allows the amount of biaxial strain to be customized lithographically, allowing the bandgaps of different germanium structures to be independently customized in a single mask process.

MAJORANA Collaboration's experience with germanium detectors

DOE PAGES

Mertens, S.; Abgrall, N.; Avignone, F. T.; ...

2015-05-01

The goal of the Majorana Demonstrator project is to search for 0νββ decay in 76Ge. Of all candidate isotopes for 0νββ, 76Ge has some of the most favorable characteristics. Germanium detectors are a well established technology, and in searches for 0νββ, the high purity germanium crystal acts simultaneously as source and detector. Furthermore, p-type germanium detectors provide excellent energy resolution and a specially designed point contact geometry allows for sensitive pulse shape discrimination. This paper will summarize the experiences the MAJORANA collaboration made with enriched germanium detectors manufactured by ORTEC®®. The process from production, to characterization and integration in MAJORANAmore » mounting structure will be described. A summary of the performance of all enriched germanium detectors will be given.« less

Probing the structural evolution of ruthenium doped germanium clusters: Photoelectron spectroscopy and density functional theory calculations

PubMed Central

Jin, Yuanyuan; Lu, Shengjie; Hermann, Andreas; Kuang, Xiaoyu; Zhang, Chuanzhao; Lu, Cheng; Xu, Hongguang; Zheng, Weijun

2016-01-01

We present a combined experimental and theoretical study of ruthenium doped germanium clusters, RuGen− (n = 3–12), and their corresponding neutral species. Photoelectron spectra of RuGen− clusters are measured at 266 nm. The vertical detachment energies (VDEs) and adiabatic detachment energies (ADEs) are obtained. Unbiased CALYPSO structure searches confirm the low-lying structures of anionic and neutral ruthenium doped germanium clusters in the size range of 3 ≤ n ≤ 12. Subsequent geometry optimizations using density functional theory (DFT) at PW91/LANL2DZ level are carried out to determine the relative stability and electronic properties of ruthenium doped germanium clusters. It is found that most of the anionic and neutral clusters have very similar global features. Although the global minimum structures of the anionic and neutral clusters are different, their respective geometries are observed as the low-lying isomers in either case. In addition, for n > 8, the Ru atom in RuGen−/0 clusters is absorbed endohedrally in the Ge cage. The theoretically predicted vertical and adiabatic detachment energies are in good agreement with the experimental measurements. The excellent agreement between DFT calculations and experiment enables a comprehensive evaluation of the geometrical and electronic structures of ruthenium doped germanium clusters. PMID:27439955

GeoEye(TradeMark) Corporate Overview

NASA Technical Reports Server (NTRS)

Jones, Dennis

2007-01-01

This viewgraph presentation gives a corporate overview of GeoEye, the world's largest commercial remote sensing company. The contents include: 1) About GeoEye; 2) GeoEye Mission; 3) The Company; 4) Com,pany Summary; 5) U.S. Government Commitment; 6) GeoEye Constellation; 7) Other Imaging Resources; 8) OrbView-3 & OrbView-2; 9) OrbView-3 System Architecture; 10) OrbView-3; 11) OrbView-2; 12) IKONOS; 13) Largest Image Archive in the World; 14) GeoEye-1; 15) Best-In-Class Development Team; 16) Highest Performance Available in the Commercial Market; and 17) Key Themes

An Injectable Glass Polyalkenoate Cement Engineered for Fracture Fixation and Stabilization

PubMed Central

Peel, Sean A. F.; Towler, Mark R.

2017-01-01

Glass polyalkenoate cements (GPCs) have potential as bio-adhesives due to their ease of application, appropriate mechanical properties, radiopacity and chemical adhesion to bone. Aluminium (Al)-free GPCs have been discussed in the literature, but have proven difficult to balance injectability with mechanical integrity. For example, zinc-based, Al-free GPCs reported compressive strengths of 63 MPa, but set in under 2 min. Here, the authors design injectable GPCs (IGPCs) based on zinc-containing, Al-free silicate compositions containing GeO2, substituted for ZnO at 3% increments through the series. The setting reactions, injectability and mechanical properties of these GPCs were evaluated using both a hand-mix (h) technique, using a spatula for sample preparation and application and an injection (i) technique, using a 16-gauge needle, post mixing, for application. GPCs ability to act as a carrier for bovine serum albumin (BSA) was also evaluated. Germanium (Ge) and BSA containing IGPCs were produced and reported to have working times between 26 and 44 min and setting times between 37 and 55 min; the extended handling properties being as a result of less Ge. The incorporation of BSA into the cement had no effect on the handling and mechanical properties, but the latter were found to have increased compression strength with the addition of Ge from between 27 and 37 MPa after 30 days maturation. PMID:28678157

Epitaxial Deposition Of Germanium Doped With Gallium

NASA Technical Reports Server (NTRS)

Huffman, James E.

1994-01-01

Epitaxial layers of germanium doped with gallium made by chemical vapor deposition. Method involves combination of techniques and materials used in chemical vapor deposition with GeH4 or GeCl4 as source of germanium and GaCl3 as source of gallium. Resulting epitaxial layers of germanium doped with gallium expected to be highly pure, with high crystalline quality. High-quality material useful in infrared sensors.

Zn2GeO4 nanowires as efficient electron injection material for electroluminescent devices.

PubMed

Wang, Jiangxin; Yan, Chaoyi; Magdassi, Shlomo; Lee, Pooi See

2013-08-14

Pure phase Zn2GeO4 nanowires (NWs) were grown by the chemical vapor transport method on p-GaN: Mg/Al2O3 substrate. The as-grown Zn2GeO4 NWs exhibited n-type characteristic due to native defects and formed a p-n heterojunction with the p-GaN substrate. The unique energy level of Zn2GeO4 NWs promotes electron injection into GaN active region while suppressing hole injection into Zn2GeO4 NWs. The device exhibited an emission centered at 426 nm and a low turn-on voltage around 4 V. Zn2GeO4 NWs are first reported in this paper as promising electron transport and injection material for electroluminescent devices.

GEO2Enrichr: browser extension and server app to extract gene sets from GEO and analyze them for biological functions.

PubMed

Gundersen, Gregory W; Jones, Matthew R; Rouillard, Andrew D; Kou, Yan; Monteiro, Caroline D; Feldmann, Axel S; Hu, Kevin S; Ma'ayan, Avi

2015-09-15

Identification of differentially expressed genes is an important step in extracting knowledge from gene expression profiling studies. The raw expression data from microarray and other high-throughput technologies is deposited into the Gene Expression Omnibus (GEO) and served as Simple Omnibus Format in Text (SOFT) files. However, to extract and analyze differentially expressed genes from GEO requires significant computational skills. Here we introduce GEO2Enrichr, a browser extension for extracting differentially expressed gene sets from GEO and analyzing those sets with Enrichr, an independent gene set enrichment analysis tool containing over 70 000 annotated gene sets organized into 75 gene-set libraries. GEO2Enrichr adds JavaScript code to GEO web-pages; this code scrapes user selected accession numbers and metadata, and then, with one click, users can submit this information to a web-server application that downloads the SOFT files, parses, cleans and normalizes the data, identifies the differentially expressed genes, and then pipes the resulting gene lists to Enrichr for downstream functional analysis. GEO2Enrichr opens a new avenue for adding functionality to major bioinformatics resources such GEO by integrating tools and resources without the need for a plug-in architecture. Importantly, GEO2Enrichr helps researchers to quickly explore hypotheses with little technical overhead, lowering the barrier of entry for biologists by automating data processing steps needed for knowledge extraction from the major repository GEO. GEO2Enrichr is an open source tool, freely available for installation as browser extensions at the Chrome Web Store and FireFox Add-ons. Documentation and a browser independent web application can be found at http://amp.pharm.mssm.edu/g2e/. avi.maayan@mssm.edu. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Germanium resistance thermometer calibration at superfluid helium temperatures

NASA Technical Reports Server (NTRS)

Mason, F. C.

1985-01-01

The rapid increase in resistance of high purity semi-conducting germanium with decreasing temperature in the superfluid helium range of temperatures makes this material highly adaptable as a very sensitive thermometer. Also, a germanium thermometer exhibits a highly reproducible resistance versus temperature characteristic curve upon cycling between liquid helium temperatures and room temperature. These two factors combine to make germanium thermometers ideally suited for measuring temperatures in many cryogenic studies at superfluid helium temperatures. One disadvantage, however, is the relatively high cost of calibrated germanium thermometers. In space helium cryogenic systems, many such thermometers are often required, leading to a high cost for calibrated thermometers. The construction of a thermometer calibration cryostat and probe which will allow for calibrating six germanium thermometers at one time, thus effecting substantial savings in the purchase of thermometers is considered.

Adhesion and friction behavior of group 4 elements germanium, silicon, tin, and lead

NASA Technical Reports Server (NTRS)

Buckley, D. H.

1975-01-01

Adhesion and friction studies were conducted with thin films of the group IV elements silicon, germanium, tin, and lead ion plated on the nickel (011) substrate. The mating surface was gold (111). Contacts were made for the elements in the clean state and with oxygen present. Adhesion and friction experiments were conducted at very light loads of 1 to 10 g. Sliding was at a speed of 0.7 mm/min. Friction results indicate that the more covalently bonded elements silicon and germanium exhibit lower adhesion and friction than the more metallic bonded tin and lead. The adhesion of gold to germanium was observed, and recrystallization of the transferred gold occurred. Plastic flow of germanium was seen with sliding. Oxygen reduced, but did not eliminate, the adhesion observed with germanium and silicon.

Black Silicon Germanium (SiGe) for Extended Wavelength Near Infrared Electro-optical Applications

DTIC Science & Technology

2010-05-01

samples were dipped in an aqueous solution of iodine (I) and potassium iodide (KI) (25 gm I and 100 gm KI per liter of water [H2O] ) (16). The samples...Satterfield, C. N.; Wentworth, R. L. in Hydrogen Peroxide , Reinhold Publishing, New York, 1955, p. 370. 12 19. Kishioka, K.; Horita, S.; Ohdaria, K...germanium H2O water HBT heterojunction bipolar transistor I iodine IPA isopropal alcohol KI potassium iodide MEE metal enhanced etching

Crystal growth of HVPE-GaN doped with germanium

NASA Astrophysics Data System (ADS)

Iwinska, M.; Takekawa, N.; Ivanov, V. Yu.; Amilusik, M.; Kruszewski, P.; Piotrzkowski, R.; Litwin-Staszewska, E.; Lucznik, B.; Fijalkowski, M.; Sochacki, T.; Teisseyre, H.; Murakami, H.; Bockowski, M.

2017-12-01

Crystallization by hydride vapor phase epitaxy method of gallium nitride single crystals doped with germanium and properties of the obtained material are described in this paper. Growth was performed in hydrogen and nitrogen carrier gas. The results were studied and compared. Influence of different flows of germanium tetrachloride, precursor of germanium, on the grown crystals was investigated. Ammonothermal GaN substrates were used as seeds for crystallization. Structural, electrical, and optical properties of HVPE-GaN doped with germanium are presented and discussed in detail. They were compared to properties of HVPE-GaN doped with silicon and also grown on native seeds of high quality.

A Low-Noise Germanium Ionization Spectrometer for Low-Background Science

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aalseth, Craig E.; Colaresi, Jim; Collar, Juan I.

2016-12-01

Recent progress on the development of very low energy threshold high purity germanium ionization spectrometers has produced an instrument of 1.2 kg mass and excellent noise performance. The detector was installed in a low-background cryostat intended for use in a low mass, WIMP dark matter direct detection search. The integrated detector and low background cryostat achieved noise performance of 98 eV full-width half-maximum of an input electronic pulse generator peak and gamma-ray energy resolution of 1.9 keV full-width half-maximum at the 60Co gamma-ray energy of 1332 keV. This Transaction reports the thermal characterization of the low-background cryostat, specifications of themore » newly prepared 1.2 kg p-type point contact germanium detector, and the ionization spectroscopy – energy resolution and energy threshold – performance of the integrated system.« less

Evaluation of Space-Based Constraints on Global Nitrogen Oxide Emissions with Regional Aircraft Measurements over and Downwind of Eastern North America

NASA Technical Reports Server (NTRS)

Martin, Randall V.; Sioris, Christopher E.; Chance, Kelly; Ryerson, Thomas B.; Flocke, Frank M.; Bertram, Timothy H.; Wooldridge, Paul J.; Cohen, Ronald C.; Neuman, J. Andy; Swanson, Aaron

2006-01-01

We retrieve tropospheric nitrogen dioxide (NO 2) columns for May 2004 to April 2005 from the SCIAMACHY satellite instrument to derive top-down emissions of nitrogen oxides (NO(x) = NO + NO2) via inverse modeling with a global chemical transport model (GEOS-Chem). Simulated NO 2 vertical profiles used in the retrieval are evaluated with airborne measurements over and downwind of North America (ICARTT); a northern midlatitude lightning source of 1.6 Tg N/yr minimizes bias in the retrieval. Retrieved NO2 columns are validated (r2 = 0.60, slope = 0.82) with coincident airborne in situ measurements. The top-down emissions are combined with a priori information from a bottom-up emission inventory with error weighting to achieve an improved a posteriori estimate of the global distribution of surface NOx emissions. Our a posteriori NOx emission inventory for land surface NOx emissions (46.1 Tg N/yr) is 22% larger than the GEIA-based a priori bottom-up inventory for 1998, a difference that reflects rising anthropogenic emissions, especially from East Asia A posteriori NOx emissions for East Asia (9.8 Tg N/yr) exceed those from other continents. The a posteriori inventory improves the GEOS-Chem simulation of NOx, peroxyacetylnitrate, and nitric acid with respect to airborne in situ measurements over and downwind of New York City. The a posteriori is 7% larger than the EDGAR 3.2FT2000 global inventory, 3% larger than the NEI99 inventory for the United States, and 68% larger than a regional inventory for 2000 for eastern Asia. SCIAMACHY NO2 columns over the North Atlantic show a weak plume from lightning NO(x).

Nucleation of the diamond phase in aluminium-solid solutions

NASA Technical Reports Server (NTRS)

Hornbogen, E.; Mukhopadhyay, A. K.; Starke, E. A., Jr.

1993-01-01

Precipitation was studied from fcc solid solutions with silicon, germanium, copper and magnesium. Of all these elements only silicon and germanium form diamond cubic (DC) precipitates in fcc Al. Nucleation of the DC structure is enhanced if both types of atom are dissolved in the fcc lattice. This is interpreted as due to atomic size effects in the prenucleation stage. There are two modes of interference of fourth elements with nucleation of the DC phase in Al + Si, Ge. The formation of the DC phase is hardly affected if the atoms (for example, copper) are rejected from the (Si, Ge)-rich clusters. If additional types of atom are attracted by silicon and/or germanium, DC nuclei are replaced by intermetallic compounds (for example Mg2Si).

GEO2D - Two-Dimensional Computer Model of a Ground Source Heat Pump System

DOE Data Explorer

James Menart

2013-06-07

This file contains a zipped file that contains many files required to run GEO2D. GEO2D is a computer code for simulating ground source heat pump (GSHP) systems in two-dimensions. GEO2D performs a detailed finite difference simulation of the heat transfer occurring within the working fluid, the tube wall, the grout, and the ground. Both horizontal and vertical wells can be simulated with this program, but it should be noted that the vertical wall is modeled as a single tube. This program also models the heat pump in conjunction with the heat transfer occurring. GEO2D simulates the heat pump and ground loop as a system. Many results are produced by GEO2D as a function of time and position, such as heat transfer rates, temperatures and heat pump performance. On top of this information from an economic comparison between the geothermal system simulated and a comparable air heat pump systems or a comparable gas, oil or propane heating systems with a vapor compression air conditioner. The version of GEO2D in the attached file has been coupled to the DOE heating and cooling load software called ENERGYPLUS. This is a great convenience for the user because heating and cooling loads are an input to GEO2D. GEO2D is a user friendly program that uses a graphical user interface for inputs and outputs. These make entering data simple and they produce many plotted results that are easy to understand. In order to run GEO2D access to MATLAB is required. If this program is not available on your computer you can download the program MCRInstaller.exe, the 64 bit version, from the MATLAB website or from this geothermal depository. This is a free download which will enable you to run GEO2D..

Modeling uncertainties for tropospheric nitrogen dioxide columns affecting satellite-based inverse modeling of nitrogen oxides emissions

NASA Astrophysics Data System (ADS)

Lin, J.-T.; Liu, Z.; Zhang, Q.; Liu, H.; Mao, J.; Zhuang, G.

2012-12-01

Errors in chemical transport models (CTMs) interpreting the relation between space-retrieved tropospheric column densities of nitrogen dioxide (NO2) and emissions of nitrogen oxides (NOx) have important consequences on the inverse modeling. They are however difficult to quantify due to lack of adequate in situ measurements, particularly over China and other developing countries. This study proposes an alternate approach for model evaluation over East China, by analyzing the sensitivity of modeled NO2 columns to errors in meteorological and chemical parameters/processes important to the nitrogen abundance. As a demonstration, it evaluates the nested version of GEOS-Chem driven by the GEOS-5 meteorology and the INTEX-B anthropogenic emissions and used with retrievals from the Ozone Monitoring Instrument (OMI) to constrain emissions of NOx. The CTM has been used extensively for such applications. Errors are examined for a comprehensive set of meteorological and chemical parameters using measurements and/or uncertainty analysis based on current knowledge. Results are exploited then for sensitivity simulations perturbing the respective parameters, as the basis of the following post-model linearized and localized first-order modification. It is found that the model meteorology likely contains errors of various magnitudes in cloud optical depth, air temperature, water vapor, boundary layer height and many other parameters. Model errors also exist in gaseous and heterogeneous reactions, aerosol optical properties and emissions of non-nitrogen species affecting the nitrogen chemistry. Modifications accounting for quantified errors in 10 selected parameters increase the NO2 columns in most areas with an average positive impact of 18% in July and 8% in January, the most important factor being modified uptake of the hydroperoxyl radical (HO2) on aerosols. This suggests a possible systematic model bias such that the top-down emissions will be overestimated by the same magnitude if the model is used for emission inversion without corrections. The modifications however cannot eliminate the large model underestimates in cities and other extremely polluted areas (particularly in the north) as compared to satellite retrievals, likely pointing to underestimates of the a priori emission inventory in these places with important implications for understanding of atmospheric chemistry and air quality. Note that these modifications are simplified and should be interpreted with caution for error apportionment.

All-inorganic Germanium nanocrystal films by cationic ligand exchange

DOE PAGES

Wheeler, Lance M.; Nichols, Asa W.; Chernomordik, Boris D.; ...

2016-01-21

In this study, we introduce a new paradigm for group IV nanocrystal surface chemistry based on room temperature surface activation that enables ionic ligand exchange. Germanium nanocrystals synthesized in a gas-phase plasma reactor are functionalized with labile, cationic alkylammonium ligands rather than with traditional covalently bound groups. We employ Fourier transform infrared and 1H nuclear magnetic resonance spectroscopies to demonstrate the alkylammonium ligands are freely exchanged on the germanium nanocrystal surface with a variety of cationic ligands, including short inorganic ligands such as ammonium and alkali metal cations. This ionic ligand exchange chemistry is used to demonstrate enhanced transport inmore » germanium nanocrystal films following ligand exchange as well as the first photovoltaic device based on an all-inorganic germanium nanocrystal absorber layer cast from solution. This new ligand chemistry should accelerate progress in utilizing germanium and other group IV nanocrystals for optoelectronic applications.« less

Germanium, Arsenic, and Selenium Abundances in Metal-poor Stars

NASA Astrophysics Data System (ADS)

Roederer, Ian U.

2012-09-01

The elements germanium (Ge, Z = 32), arsenic (As, Z = 33), and selenium (Se, Z = 34) span the transition from charged-particle or explosive synthesis of the iron-group elements to neutron-capture synthesis of heavier elements. Among these three elements, only the chemical evolution of germanium has been studied previously. Here we use archive observations made with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope and observations from several ground-based facilities to study the chemical enrichment histories of seven stars with metallicities -2.6 <= [Fe/H] <= -0.4. We perform a standard abundance analysis of germanium, arsenic, selenium, and several other elements produced by neutron-capture reactions. When combined with previous derivations of germanium abundances in metal-poor stars, our sample reveals an increase in the [Ge/Fe] ratios at higher metallicities. This could mark the onset of the weak s-process contribution to germanium. In contrast, the [As/Fe] and [Se/Fe] ratios remain roughly constant. These data do not directly indicate the origin of germanium, arsenic, and selenium at low metallicity, but they suggest that the weak and main components of the s-process are not likely sources. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. This research made use of StarCAT, hosted by the Mikulski Archive at the Space Telescope Science Institute (MAST). These data are associated with Programs GO-7348, GO-7433, GO-8197, GO-9048, GO-9455, and GO-9804.Based on data obtained from the European Southern Observatory (ESO) Science Archive Facility. These data are associated with Programs 67.D-0439(A), 074.C-0364(A), 076.B-0055(A), and 080.D-0347(A).This research has made use of the Keck Observatory Archive (KOA), which is operated by the W.M. Keck Observatory and the NASA Exoplanet Science Institute (NExScI), under contract with the National Aeronautics and Space Administration. These data are associated with Programs H2aH, H6aH, and H39aH (PI: Boesgaard), N01H (PI: Latham), and U11H (PI: Prochaska).This paper includes data taken at The McDonald Observatory of The University of Texas at Austin.

Organotrichlorogermane synthesis by the reaction of elemental germanium, tetrachlorogermane and organic chloride via dichlorogermylene intermediate.

PubMed

Okamoto, Masaki; Asano, Takuya; Suzuki, Eiichi

2004-08-07

Organotrichlorogermanes were synthesized by the reaction of elemental germanium, tetrachlorogermane and organic chlorides, methyl, propyl, isopropyl and allyl chlorides. Dichlorogermylene formed by the reaction of elemental germanium with tetrachlorogermane was the reaction intermediate, which was inserted into the carbon-chlorine bond of the organic chloride to give organotrichlorogermane. When isopropyl or allyl chloride was used as an organic chloride, organotrichlorogermane was formed also in the absence of tetrachlorogermane. These chlorides were converted to hydrogen chloride, which subsequently reacted with elemental germanium to give the dichlorogermylene intermediate. The reaction of elemental germanium, tetrachlorogermane and organic chlorides provides a simple and easy method for synthesizing organotrichlorogermanes, and all the raw materials are easily available.

Disilane chemisorption on Si(x)Ge(1-x)(100)-(2 x 1): molecular mechanisms and implications for film growth rates.

PubMed

Ng, Rachel Qiao-Ming; Tok, E S; Kang, H Chuan

2009-07-28

At low temperatures, hydrogen desorption is known to be the rate-limiting process in silicon germanium film growth via chemical vapor deposition. Since surface germanium lowers the hydrogen desorption barrier, Si(x)Ge((1-x)) film growth rate increases with the surface germanium fraction. At high temperatures, however, the molecular mechanisms determining the epitaxial growth rate are not well established despite much experimental work. We investigate these mechanisms in the context of disilane adsorption because disilane is an important precursor used in film growth. In particular, we want to understand the molecular steps that lead, in the high temperature regime, to a decrease in growth rate as the surface germanium increases. In addition, there is a need to consider the issue of whether disilane adsorbs via silicon-silicon bond dissociation or via silicon-hydrogen bond dissociation. It is usually assumed that disilane adsorption occurs via silicon-silicon bond dissociation, but in recent work we provided theoretical evidence that silicon-hydrogen bond dissociation is more important. In order to address these issues, we calculate the chemisorption barriers for disilane on silicon germanium using first-principles density functional theory methods. We use the calculated barriers to estimate film growth rates that are then critically compared to the experimental data. This enables us to establish a connection between the dependence of the film growth rate on the surface germanium content and the kinetics of the initial adsorption step. We show that the generally accepted mechanism where disilane chemisorbs via silicon-silicon bond dissociation is not consistent with the data for film growth kinetics. Silicon-hydrogen bond dissociation paths have to be included in order to give good agreement with the experimental data for high temperature film growth rate.

Structural Design Parameters for Germanium

NASA Technical Reports Server (NTRS)

Salem, Jon; Rogers, Richard; Baker, Eric

2017-01-01

The fracture toughness and slow crack growth parameters of germanium supplied as single crystal beams and coarse grain disks were measured. Although germanium is anisotropic (A* 1.7), it is not as anisotropic as SiC, NiAl, or Cu. Thus the fracture toughness was similar on the 100, 110, and 111 planes, however, measurements associated with randomly oriented grinding cracks were 6 to 30 higher. Crack extension in ring loaded disks occurred on the 111 planes due to both the lower fracture energy and the higher stresses on stiff 111 planes. Germanium exhibits a Weibull scale effect, but does not exhibit significant slow crack growth in distilled water. (n 100), implying that design for quasi static loading can be performed with scaled strength statistics. Practical values for engineering design are a fracture toughness of 0.69 0.02 MPam (megapascals per square root meter) and a Weibull modulus of m 6 2. For well ground and reasonable handled coupons, average fracture strength should be greater than 40 megapascals. Aggregate, polycrystalline elastic constants are Epoly 131 gigapascals, vpoly 0.22.

Germanium precipitation from collecting-mains liquor with tannin extract in an alkaline medium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Medvedev, K.P.; Mikhailov, N.F.; Petrapol'skaya, V.M.

1976-01-01

It is proposed to precipitate germanium in a slightly alkaline medium, with a neutral solution of tannin extract in aqueous alkali. The effects of various factors on germanium recovery from collecting-mains liquors have been studied.

Dramatic Changes in Thermoelectric Power of Germanium under Pressure: Printing n–p Junctions by Applied Stress

PubMed Central

Korobeinikov, Igor V.; Morozova, Natalia V.; Shchennikov, Vladimir V.; Ovsyannikov, Sergey V.

2017-01-01

Controlled tuning the electrical, optical, magnetic, mechanical and other characteristics of the leading semiconducting materials is one of the primary technological challenges. Here, we demonstrate that the electronic transport properties of conventional single-crystalline wafers of germanium may be dramatically tuned by application of moderate pressures. We investigated the thermoelectric power (Seebeck coefficient) of p– and n–type germanium under high pressure to 20 GPa. We established that an applied pressure of several GPa drastically shifts the electrical conduction to p–type. The p–type conduction is conserved across the semiconductor-metal phase transition at near 10 GPa. Upon pressure releasing, germanium transformed to a metastable st12 phase (Ge-III) with n–type semiconducting conductivity. We proposed that the unusual electronic properties of germanium in the original cubic-diamond-structured phase could result from a splitting of the “heavy” and “light” holes bands, and a related charge transfer between them. We suggested new innovative applications of germanium, e.g., in technologies of printing of n–p and n–p–n junctions by applied stress. Thus, our work has uncovered a new face of germanium as a ‘smart’ material. PMID:28290495

Influence of Containment on the Growth of Germanium-Silicon in Microgravity

NASA Technical Reports Server (NTRS)

Volz, M. P.; Mazuruk, K.; Croll, A.; Sorgenfrei, T.

2017-01-01

This investigation involves the comparison of results achieved from three types of crystal growth of germanium and germanium-silicon alloys: Float zone growth, Bridgman growth, and Detached Bridgman growth. The fundamental goal of the proposed research is to determine the influence of containment on the processing-induced defects and impurity incorporation in germanium-silicon (GeSi) crystals (silicon concentration in the solid up to 5%) for three different growth configurations in order to quantitatively assess the improvements of crystal quality possible by detached growth.

Germanate Glass Fiber Lasers for High Power

DTIC Science & Technology

2016-01-04

melting in the lab. KGe027: 60GeO2-a PbO-b La2O3-c Na2O (GPLN1) KGe028: 56GeO2-d PbO-e Ga2O3 -f Na2O (GPGN2) KGe029: 55GeO2-g PbO-h BaO-I ZnO-j K2O...Raw materials in the form of powder with high purity (GeO2 – 99.999%, PbO – 99.99%, Ga2O3 – 99.995 and Na2CO3 – 99.997%) were used. Batched samples...analysis techniques, this 18 month project by a team of researchers found that germanate based on 56%GeO2-31%PbO-4% Ga2O3 -9%Na2O (GPGN) had the lowest

Broadband telecom to mid-infrared supercontinuum generation in a dispersion-engineered silicon germanium waveguide.

PubMed

Ettabib, Mohamed A; Xu, Lin; Bogris, Adonis; Kapsalis, Alexandros; Belal, Mohammad; Lorent, Emerick; Labeye, Pierre; Nicoletti, Sergio; Hammani, Kamal; Syvridis, Dimitris; Shepherd, David P; Price, Jonathan H V; Richardson, David J; Petropoulos, Periklis

2015-09-01

We demonstrate broadband supercontinuum generation (SCG) in a dispersion-engineered silicon-germanium waveguide. The 3 cm long waveguide is pumped by femtosecond pulses at 2.4 μm, and the generated supercontinuum extends from 1.45 to 2.79 μm (at the -30  dB point). The broadening is mainly driven by the generation of a dispersive wave in the 1.5-1.8 μm region and soliton fission. The SCG was modeled numerically, and excellent agreement with the experimental results was obtained.

Enhanced photoluminescence and phosphorescence properties of green phosphor Zn2GeO4:Mn(2+)via composition modification with GeO2 and MgF2.

PubMed

Pan, Yuexiao; Li, Li; Lu, Jing; Pang, Ran; Wan, Li; Huang, Shaoming

2016-06-21

A green long-lasting phosphorescence (LLP) phosphor Zn2GeO4:Mn(2+) (ZGOM) has been synthesized by a solid-state method at 1100 °C in air. The luminescence intensity has been improved up to 9 and 6 times through mixing GeO2 and MgF2 into the composition, respectively. The phosphorescence duration of the sample has been prolonged to 5 h. The phosphor, composed of a mixture of Zn2GeO4 (ZGO), GeO2, and MgGeO3 phases, emits enhanced green luminescence with a broad excitation band between 250 nm to 400 nm. Under identical measurement conditions, the optimized phosphor ZGOM has a higher emission intensity and shows longer wavelength emission than those of the commercial green LLP phosphor SrAl2O4:Eu,Dy (SAOED) under an excitation at 336 nm. The quantum yield of the sample modified by GeO2 and MgF2 is as high as 95.0%. Understanding of the formation mechanism for enhancement of emission intensity and prolonging of phosphorescence duration of ZGOM is fundamentally important, which might be extended to other identified solid-state inorganic phosphor materials for advanced properties.

Comparative study of GeO 2/Ge and SiO 2/Si structures on anomalous charging of oxide films upon water adsorption revealed by ambient-pressure X-ray photoelectron spectroscopy

DOE PAGES

Mori, Daichi; Oka, Hiroshi; Hosoi, Takuji; ...

2016-09-02

The energy difference between the oxide and bulk peaks in X-ray photoelectron spectroscopy (XPS) spectra was investigated in this paper for both GeO 2/Ge and SiO 2/Si structures with thickness-controlled water films. This was achieved by obtaining XPS spectra at various values of relative humidity (RH) of up to ~15%. The increase in the energy shift is more significant for thermal GeO 2 on Ge than for thermal SiO 2 on Si above ~10 -4% RH, which is due to the larger amount of water molecules that infiltrate into the GeO 2 film to form hydroxyls. Analyzing the origins ofmore » this energy shift, we propose that the positive charging of a partially hydroxylated GeO 2 film, which is unrelated to X-ray irradiation, causes the larger energy shift for GeO 2/Ge than for SiO 2/Si. A possible microscopic mechanism of this intrinsic positive charging is the emission of electrons from adsorbed water species in the suboxide layer of the GeO 2 film to the Ge bulk, leaving immobile cations or positively charged states in the oxide. Finally, this may be related to the reported negative shift of flat band voltages in metal-oxide-semiconductor diodes with an air-exposed GeO 2 layer.« less

Germanium detector passivated with hydrogenated amorphous germanium

DOEpatents

Hansen, William L.; Haller, Eugene E.

1986-01-01

Passivation of predominantly crystalline semiconductor devices (12) is provided for by a surface coating (21) of sputtered hydrogenated amorphous semiconductor material. Passivation of a radiation detector germanium diode, for example, is realized by sputtering a coating (21) of amorphous germanium onto the etched and quenched diode surface (11) in a low pressure atmosphere of hydrogen and argon. Unlike prior germanium diode semiconductor devices (12), which must be maintained in vacuum at cryogenic temperatures to avoid deterioration, a diode processed in the described manner may be stored in air at room temperature or otherwise exposed to a variety of environmental conditions. The coating (21) compensates for pre-existing undesirable surface states as well as protecting the semiconductor device (12) against future impregnation with impurities.

Passivation of Ge/high-κ interface using RF Plasma nitridation

NASA Astrophysics Data System (ADS)

Dushaq, Ghada; Nayfeh, Ammar; Rasras, Mahmoud

2018-01-01

In this paper, plasma nitridation of a germanium surface using NH3 and N2 gases is performed with a standard RF-PECVD method at a substrate temperature of 250 °C. The structural and optical properties of the Ge surface have been investigated using Atomic Force Microscopy (AFM), Fourier Transform Infrared Spectroscopy (FT-IR), and Variable Angle Spectroscopic Ellipsometery (VASE). Study of the Ge (100) surface revealed that it is nitrated after plasma treatment while the GeO2 regrowth on the surface has been suppressed. Also, stability of the treated surface under air exposure is observed, where all the measurements were performed at room ambient. The electrical characteristics of fabricated Al/Ti/HfO2/GeON/p-Ge capacitors using the proposed surface treatment technique have been investigated. The C-V curves indicated a negligible hysteresis compared to ˜500 mV observed in untreated samples. Additionally, the C-V characteristic is used to extract the high-κ/Ge interface trap density using the most commonly used methods in determining the interface traps. The discussion includes the Dit calculation from the high-low frequency (Castagné-Vapaille) method and Terman (high-frequency) method. The high-low frequency method indicated a low interface trap density of ˜2.5 × 1011 eV-1.cm-2 compared to the Terman method. The J-V measurements revealed more than two orders of magnitude reduction of the gate leakage. This improved Ge interface quality is a promising low-temperature technique for fabricating high-performance Ge MOSFETs.

GeoSciML v3.0 - a significant upgrade of the CGI-IUGS geoscience data model

NASA Astrophysics Data System (ADS)

Raymond, O.; Duclaux, G.; Boisvert, E.; Cipolloni, C.; Cox, S.; Laxton, J.; Letourneau, F.; Richard, S.; Ritchie, A.; Sen, M.; Serrano, J.-J.; Simons, B.; Vuollo, J.

2012-04-01

GeoSciML version 3.0 (http://www.geosciml.org), released in late 2011, is the latest version of the CGI-IUGS* Interoperability Working Group geoscience data interchange standard. The new version is a significant upgrade and refactoring of GeoSciML v2 which was released in 2008. GeoSciML v3 has already been adopted by several major international interoperability initiatives, including OneGeology, the EU INSPIRE program, and the US Geoscience Information Network, as their standard data exchange format for geoscience data. GeoSciML v3 makes use of recently upgraded versions of several Open Geospatial Consortium (OGC) and ISO data transfer standards, including GML v3.2, SWE Common v2.0, and Observations and Measurements v2 (ISO 19156). The GeoSciML v3 data model has been refactored from a single large application schema with many packages, into a number of smaller, but related, application schema modules with individual namespaces. This refactoring allows the use and future development of modules of GeoSciML (eg; GeologicUnit, GeologicStructure, GeologicAge, Borehole) in smaller, more manageable units. As a result of this refactoring and the integration with new OGC and ISO standards, GeoSciML v3 is not backwardly compatible with previous GeoSciML versions. The scope of GeoSciML has been extended in version 3.0 to include new models for geomorphological data (a Geomorphology application schema), and for geological specimens, geochronological interpretations, and metadata for geochemical and geochronological analyses (a LaboratoryAnalysis-Specimen application schema). In addition, there is better support for borehole data, and the PhysicalProperties model now supports a wider range of petrophysical measurements. The previously used CGI_Value data type has been superseded in favour of externally governed data types provided by OGC's SWE Common v2 and GML v3.2 data standards. The GeoSciML v3 release includes worked examples of best practice in delivering geochemical analytical data using the Observations and Measurements (ISO19156) and SWE Common v2 models. The GeoSciML v3 data model does not include vocabularies to support the data model. However, it does provide a standard pattern to reference controlled vocabulary concepts using HTTP-URIs. The international GeoSciML community has developed distributed RDF-based geoscience vocabularies that can be accessed by GeoSciML web services using the standard pattern recommended in GeoSciML v3. GeoSciML v3 is the first version of GeoSciML that will be accompanied by web service validation tools using Schematron rules. For example, these validation tools may check for compliance of a web service to a particular profile of GeoSciML, or for logical consistency of data content that cannot be enforced by the application schemas. This validation process will support accreditation of GeoSciML services and a higher degree of semantic interoperability. * International Union of Geological Sciences Commission for Management and Application of Geoscience Information (CGI-IUGS)

Advances in fractal germanium micro/nanoclusters induced by gold: microstructures and properties.

PubMed

Chen, Zhiwen; Shek, Chan-Hung; Wu, C M Lawrence; Lai, Joseph K L

2014-02-01

Germanium materials are a class of unique semiconductor materials with widespread technological applications because of their valuable semiconducting, electrical, optical, and thermoelectric power properties in the fields of macro/mesoscopic materials and micro/nanodevices. In this review, we describe the efforts toward understanding the microstructures and various properties of the fractal germanium micro/nanoclusters induced by gold prepared by high vacuum thermal evaporation techniques, highlighting contributions from our laboratory. First, we present the integer and non-integer dimensional germanium micro/nanoclusters such as nanoparticles, nanorings, and nanofractals induced by gold and annealing. In particular, the nonlinear electrical behavior of a gold/germanium bilayer film with the interesting nanofractal is discussed in detail. In addition, the third-order optical nonlinearities of the fractal germanium nanocrystals embedded in gold matrix will be summarized by using the sensitive and reliable Z-scan techniques aimed to determine the nonlinear absorption coefficient and nonlinear refractive index. Finally, we emphasize the thermoelectric power properties of the gold/germanium bilayer films. The thermoelectric power measurement is considered to be a more effective method than the conductivity for investigating superlocalization in a percolating system. This research may provide a novel insight to modulate their competent performance and promote rational design of micro/nanodevices. Once mastered, germanium thin films with a variety of fascinating micro/nanoclusters will offer vast and unforeseen opportunities in the semiconductor industry as well as in other fields of science and technology.

Analyses of the solid earth and ocean tidal perturbations on the orbits of the Geos 1 and Geos 2 satellites

NASA Technical Reports Server (NTRS)

Felsentreger, T. L.; Marsh, J. G.; Agreen, R. W.

1976-01-01

Perturbations in the inclination of the Geos 1 and Geos 2 satellite orbits have been analyzed for the solid earth and ocean tide contributions. Precision reduced camera and Tranet Doppler observations spanning periods of over 600 days for each satellite were used to derive mean orbital elements. Perturbations due to the earth's gravity field, solar radiation pressure, and atmospheric drag were modeled, and the resulting inclination residuals were analyzed for tidal effects. The amplitudes of the observed total tidal effects were about 1.2 arc sec (36 m) in the inclination of Geos 1 and 4.5 arc sec (135 m) for Geos 2. The solid earth tides were then modeled by using the Love number 0.30. The resulting inclination residuals were then analyzed for ocean tide spherical harmonic parameters.

Effects of carboxymethyl cellulose incorporated with garlic essential oil composite coatings for improving quality of strawberries.

PubMed

Dong, Feng; Wang, Xiaolin

2017-11-01

The present study was aimed to determine the effects of carboxymethyl cellulose (CMC)/garlic essential oil (GEO) composite coatings in improving the quality of strawberries stored at 20°C and 35-40% RH. To find the effects of CMC/GEO composite coatings, strawberries were coated with CMC, CMC+GEO (1%), CMC+GEO (2%), CMC+GEO (3%) and stored, while the uncoated strawberries were taken as control during storing. The effectiveness of CMC/GEO composite coatings was evaluated by measuring their weight loss, decay percentage, ascorbic acid, total phenols, anthocyanins, titratable acidity, total soluble solids and sensory evaluation. After 6days of storage, CMC+GEO (2%) composite coatings was found very effective in decreasing the senescence and maintaining the nutritional contents of strawberries. Results of this study confirm that CMC/GEO composite coatings can be used to improve the quality of strawberries. Copyright © 2017. Published by Elsevier B.V.

40 CFR 421.186 - Pretreatment standards for new sources.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Germanium and Gallium Subcategory § 421.186 Pretreatment standards for new sources. Except as provided in 40... sources. The mass of wastewater pollutants in primary and secondary germanium and gallium process... Primary and Secondary Germanium and Gallium Subcategory Pollutant or pollutant property Maximum for any 1...

40 CFR 421.184 - Standards of performance for new sources.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Secondary Germanium and Gallium Subcategory § 421.184 Standards of performance for new sources. Any new... liquor. NSPS for the Primary and Secondary Germanium and Gallium Subcategory Pollutant or pollutant... air pollution control. NSPS for the Primary and Secondary Germanium and Gallium Subcategory Pollutant...

40 CFR 421.185 - Pretreatment standards for existing sources.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Secondary Germanium and Gallium Subcategory § 421.185 Pretreatment standards for existing sources. Except as... germanium and gallium process wastewater introduced into a POTW must not exceed the following values: (a) Still liquor. PSES for the Primary and Secondary Germanium and Gallium Subcategory Pollutant or...

40 CFR 421.184 - Standards of performance for new sources.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Secondary Germanium and Gallium Subcategory § 421.184 Standards of performance for new sources. Any new... liquor. NSPS for the Primary and Secondary Germanium and Gallium Subcategory Pollutant or pollutant... air pollution control. NSPS for the Primary and Secondary Germanium and Gallium Subcategory Pollutant...

40 CFR 421.185 - Pretreatment standards for existing sources.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Secondary Germanium and Gallium Subcategory § 421.185 Pretreatment standards for existing sources. Except as... germanium and gallium process wastewater introduced into a POTW must not exceed the following values: (a) Still liquor. PSES for the Primary and Secondary Germanium and Gallium Subcategory Pollutant or...

40 CFR 421.186 - Pretreatment standards for new sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Germanium and Gallium Subcategory § 421.186 Pretreatment standards for new sources. Except as provided in 40... sources. The mass of wastewater pollutants in primary and secondary germanium and gallium process... Primary and Secondary Germanium and Gallium Subcategory Pollutant or pollutant property Maximum for any 1...

40 CFR 421.185 - Pretreatment standards for existing sources.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Secondary Germanium and Gallium Subcategory § 421.185 Pretreatment standards for existing sources. Except as... germanium and gallium process wastewater introduced into a POTW must not exceed the following values: (a) Still liquor. PSES for the Primary and Secondary Germanium and Gallium Subcategory Pollutant or...

40 CFR 421.186 - Pretreatment standards for new sources.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Germanium and Gallium Subcategory § 421.186 Pretreatment standards for new sources. Except as provided in 40... sources. The mass of wastewater pollutants in primary and secondary germanium and gallium process... Primary and Secondary Germanium and Gallium Subcategory Pollutant or pollutant property Maximum for any 1...

40 CFR 421.186 - Pretreatment standards for new sources.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Germanium and Gallium Subcategory § 421.186 Pretreatment standards for new sources. Except as provided in 40... sources. The mass of wastewater pollutants in primary and secondary germanium and gallium process... Primary and Secondary Germanium and Gallium Subcategory Pollutant or pollutant property Maximum for any 1...

40 CFR 421.185 - Pretreatment standards for existing sources.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Secondary Germanium and Gallium Subcategory § 421.185 Pretreatment standards for existing sources. Except as... germanium and gallium process wastewater introduced into a POTW must not exceed the following values: (a) Still liquor. PSES for the Primary and Secondary Germanium and Gallium Subcategory Pollutant or...

40 CFR 421.186 - Pretreatment standards for new sources.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Germanium and Gallium Subcategory § 421.186 Pretreatment standards for new sources. Except as provided in 40... sources. The mass of wastewater pollutants in primary and secondary germanium and gallium process... Primary and Secondary Germanium and Gallium Subcategory Pollutant or pollutant property Maximum for any 1...

40 CFR 421.185 - Pretreatment standards for existing sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Secondary Germanium and Gallium Subcategory § 421.185 Pretreatment standards for existing sources. Except as... germanium and gallium process wastewater introduced into a POTW must not exceed the following values: (a) Still liquor. PSES for the Primary and Secondary Germanium and Gallium Subcategory Pollutant or...

40 CFR 421.184 - Standards of performance for new sources.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Secondary Germanium and Gallium Subcategory § 421.184 Standards of performance for new sources. Any new... liquor. NSPS for the Primary and Secondary Germanium and Gallium Subcategory Pollutant or pollutant... air pollution control. NSPS for the Primary and Secondary Germanium and Gallium Subcategory Pollutant...

40 CFR 421.184 - Standards of performance for new sources.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Secondary Germanium and Gallium Subcategory § 421.184 Standards of performance for new sources. Any new... liquor. NSPS for the Primary and Secondary Germanium and Gallium Subcategory Pollutant or pollutant... air pollution control. NSPS for the Primary and Secondary Germanium and Gallium Subcategory Pollutant...

40 CFR 421.184 - Standards of performance for new sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Secondary Germanium and Gallium Subcategory § 421.184 Standards of performance for new sources. Any new... liquor. NSPS for the Primary and Secondary Germanium and Gallium Subcategory Pollutant or pollutant... air pollution control. NSPS for the Primary and Secondary Germanium and Gallium Subcategory Pollutant...

A new approach for monthly updates of anthropogenic sulfur dioxide emissions from space: Application to China and implications for air quality forecasts

NASA Astrophysics Data System (ADS)

Wang, Yi; Wang, Jun; Xu, Xiaoguang; Henze, Daven K.; Wang, Yuxuan; Qu, Zhen

2016-09-01

SO2 emissions, the largest source of anthropogenic aerosols, can respond rapidly to economic and policy driven changes. However, bottom-up SO2 inventories have inherent limitations owing to 24-48 months latency and lack of month-to-month variation in emissions (especially in developing countries). This study develops a new approach that integrates Ozone Monitoring Instrument (OMI) SO2 satellite measurements and GEOS-Chem adjoint model simulations to constrain monthly anthropogenic SO2 emissions. The approach's effectiveness is demonstrated for 14 months in East Asia; resultant posterior emissions not only capture a 20% SO2 emission reduction in Beijing during the 2008 Olympic Games but also improve agreement between modeled and in situ surface measurements. Further analysis reveals that posterior emissions estimates, compared to the prior, lead to significant improvements in forecasting monthly surface and columnar SO2. With the pending availability of geostationary measurements of tropospheric composition, we show that it may soon be possible to rapidly constrain SO2 emissions and associated air quality predictions at fine spatiotemporal scales.

Foraminiferal calcification and CO2

NASA Astrophysics Data System (ADS)

Nooijer, L. D.; Toyofuku, T.; Reichart, G. J.

2017-12-01

Ongoing burning of fossil fuels increases atmospheric CO2, elevates marine dissolved CO2 and decreases pH and the saturation state with respect to calcium carbonate. Intuitively this should decrease the ability of CaCO3-producing organisms to build their skeletons and shells. Whereas on geological time scales weathering and carbonate deposition removes carbon from the geo-biosphere, on time scales up to thousands of years, carbonate precipitation increases pCO2 because of the associated shift in seawater carbon speciation. Hence reduced calcification provides a potentially important negative feedback on increased pCO2 levels. Here we show that foraminifera form their calcium carbonate by active proton pumping. This elevates the internal pH and acidifies the direct foraminiferal surrounding. This also creates a strong pCO2 gradient and facilitates the uptake of DIC in the form of carbon dioxide. This finding uncouples saturation state from calcification and predicts that the added carbon due to ocean acidification will promote calcification by these organisms. This unknown effect could add substantially to atmospheric pCO2 levels, and might need to be accounted for in future mitigation strategies.

Far-Infrared Magneto-Optical Studies in Germanium and Indium-Antimonide at High Intensities

NASA Astrophysics Data System (ADS)

Leung, Michael

Observations of nonlinear magneto-optical phenomena occurring in p-type Germanium and n-type Indium Antimonide are reported. These include multi-photon ionization of impurity states, and a new observation, the magneto-photon ionization of impurity states, and a new observation, the magneto-photon drag effect. A novel source of far-infrared radiation has been used. This source uses a pulsed CO(,2) LASER to optically pump a super-radiant cell, generating light with intensities up to 100 KW/cm('2) and wavelengths from 66 (mu)m to 496 (mu)m in a pulse of 150 nanoseconds duration. The Germanium samples were doped with Gallium, which is a shallow acceptor with an ionization potential of 11 meV. At liquid Helium temperature virtually all charge carriers are bound to acceptor sites. However, the high intensity radiation unexpectedly ionizes the acceptors. This is demonstrated through measurements of photoconductivity, transmission and the photo-Hall Effect. This observation is unexpected because the photon energy is one-fourth the ionization potential. Rate equations describing sequential multiphoton excitations are in agreement with the experimental results. The intermediate states are postulated to be acceptor exciton band states. Studies of the photoexcited mobility at 496 (mu)m suggest that at non-saturating levels of photoexcitation, the primary scattering mechanism of hot holes in Germanium is by neutral impurities. A new magneto-optical effect, the magneto-photon drag effect, has been studied in both Germanium and Indium Antimonide. This is simply the absorption of momentum by free carriers, from an incident photon field. It has been found that the mechanism for this effect is different in the two materials. In Germanium, the effect occurs when carriers make optical transitions from the heavy hole band to the light hole band. Thus, the magneto-optical behavior depends heavily upon the band structure. On the other hand, a modified Drude model (independent electron) has been found to be reasonably successful in describing the effect in InSb. The inclusion of non-parabolicity and hot electron effects gives a consistent description of the experimental observations.

40 CFR 421.182 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2012 CFR

2012-07-01

... CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.182 Effluent limitations guidelines...) Still liquor. BPT Limitations for the Primary and Secondary Germanium and Gallium Subcategory Pollutant... Secondary Germanium and Gallium Subcategory Pollutant or pollutant property Maximum for any 1 day Maximum...

40 CFR 421.182 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2010 CFR

2010-07-01

... CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.182 Effluent limitations guidelines...) Still liquor. BPT Limitations for the Primary and Secondary Germanium and Gallium Subcategory Pollutant... Secondary Germanium and Gallium Subcategory Pollutant or pollutant property Maximum for any 1 day Maximum...

40 CFR 421.182 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2014 CFR

2014-07-01

... CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.182 Effluent limitations guidelines...) Still liquor. BPT Limitations for the Primary and Secondary Germanium and Gallium Subcategory Pollutant... Secondary Germanium and Gallium Subcategory Pollutant or pollutant property Maximum for any 1 day Maximum...

40 CFR 421.182 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2013 CFR

2013-07-01

... CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.182 Effluent limitations guidelines...) Still liquor. BPT Limitations for the Primary and Secondary Germanium and Gallium Subcategory Pollutant... Secondary Germanium and Gallium Subcategory Pollutant or pollutant property Maximum for any 1 day Maximum...

40 CFR 421.182 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2011 CFR

2011-07-01

... CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.182 Effluent limitations guidelines...) Still liquor. BPT Limitations for the Primary and Secondary Germanium and Gallium Subcategory Pollutant... Secondary Germanium and Gallium Subcategory Pollutant or pollutant property Maximum for any 1 day Maximum...

Electronic considerations for externally segmented germanium detectors

NASA Technical Reports Server (NTRS)

Madden, N. W.; Landis, D. A.; Goulding, F. S.; Pehl, R. H.; Cork, C. P.; Luke, P. N.; Malone, D. F.; Pollard, M. J.

1991-01-01

The dominant background source for germanium gamma ray detector spectrometers used for some astrophysics observations is internal beta decay. Externally segmented germanium gamma ray coaxial detectors can identify beta decay by localizing the event. Energetic gamma rays interact in the germanium detector by multiple Compton interactions while beta decay is a local process. In order to recognize the difference between gamma rays and beta decay events, the external electrode (outside of detector) is electrically partitioned. The instrumentation of these external segments and the consequence with respect to the spectrometer energy signal is examined.

Ge(14)[Ge(SiMe(3))(3)](5)Li(3)(THF)(6): the largest metalloid cluster compound of germanium: on the way to fullerene-like compounds?

PubMed

Schenk, Christian; Schnepf, Andreas

2008-10-14

The reaction of GeBr with LiGe(SiMe(3))(3) yields the largest metalloid cluster compound of germanium Ge(14)[Ge(SiMe(3))(3)](5)Li(3)(THF)(6), in which 14 germanium atoms are arranged as a hollow sphere in the cluster core, showing that in the case of germanium also fullerene-like compounds might be present in the borderland between the molecular and solid states.

Quantum interference magnetoconductance of polycrystalline germanium films in the variable-range hopping regime

NASA Astrophysics Data System (ADS)

Li, Zhaoguo; Peng, Liping; Zhang, Jicheng; Li, Jia; Zeng, Yong; Zhan, Zhiqiang; Wu, Weidong

2018-06-01

Direct evidence of quantum interference magnetotransport in polycrystalline germanium films in the variable-range hopping (VRH) regime is reported. The temperature dependence of the conductivity of germanium films fulfilled the Mott VRH mechanism with the form of ? in the low-temperature regime (?). For the magnetotransport behaviour of our germanium films in the VRH regime, a crossover, from negative magnetoconductance at the low-field to positive magnetoconductance at the high-field, is observed while the zero-field conductivity is higher than the critical value (?). In the regime of ?, the magnetoconductance is positive and quadratic in the field for some germanium films. These features are in agreement with the VRH magnetotransport theory based on the quantum interference effect among random paths in the hopping process.

Formation of Porous Germanium Layers by Silver-Ion Implantation

NASA Astrophysics Data System (ADS)

Stepanov, A. L.; Vorob'ev, V. V.; Nuzhdin, V. I.; Valeev, V. F.; Osin, Yu. N.

2018-04-01

We propose a method for the formation of porous germanium ( P-Ge) layers containing silver nanoparticles by means of high-dose implantation of low-energy Ag+ ions into single-crystalline germanium ( c-Ge). This is demonstrated by implantation of 30-keV Ag+ ions into a polished c-Ge plate to a dose of 1.5 × 1017 ion/cm2 at an ion beam-current density of 5 μA/cm2. Examination by high-resolution scanning electron microscopy (SEM), atomic-force microscopy (AFM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX) microanalysis, and reflection high-energy electron diffraction (RHEED) showed that the implantation of silver ions into c-Ge surface led to the formation of a P-Ge layer with spongy structure comprising a network of interwoven nanofibers with an average diameter of ˜10-20 nm Ag nanoparticles on the ends of fibers. It is also established that the formation of pores during Ag+ ion implantation is accompanied by effective sputtering of the Ge surface.

DLTS analysis of radiation-induced defects in one-MeV electron irradiated germanium and Alsub0.17Gasub0.83As solar cells

NASA Technical Reports Server (NTRS)

Li, S. B.; Choi, C. G.; Loo, R. Y.

1985-01-01

The radiation-induced deep-level defects in one-MeV electron-irradiated germanium and AlxGal-xAs solar cell materials using the deep-level transient spectroscopy (DLTS) and C-V techniques were investigated. Defect and recombination parameters such as defect density and energy levels, capture cross sections and lifetimes for both electron and hole traps were determined. The germanium and AlGaAs p/n junction cells were irradiated by one-MeV electrons. The DLTS, I-V, and C-V measurements were performed on these cells. The results are summarized as follows: (1) for the irradiated germanium samples, the dominant electron trap was due to the E sub - 0.24 eV level with density around 4x10 to the 14th power 1/cu cm, independent of electron fluence, its origin is attributed to the vacancy-donor complex defect formed during the electron irradiation; (2) in the one-MeV electron irradiated Al0.17Ga0.83 as sample, two dominant electron traps with energies of Ec-0.19 and -0.29 eV were observed, the density for both electron traps remained nearly constant, independent of electron fluence. It is shown that one-MeV electron irradiation creates very few or no new deep-level traps in both the germanium and AlxGa1-xAs cells, and are suitable for fabricating the radiation-hard high efficiency multijunction solar cells for space applications.

Performance of Versions 1,2 and 3 of the Goddard Earth Observing System (GEOS) Chemistry-Climate Model (CCM)

NASA Technical Reports Server (NTRS)

Pawson, Steven; Stolarski, Richard S.; Nielsen, J. Eric; Duncan, Bryan N.

2008-01-01

Version 1 of the Goddard Earth Observing System Chemistry-Climate Model (GEOS CCM) was used in the first CCMVa1 model evaluation and forms the basis for several studies of links between ozone and the circulation. That version of the CCM was based on the GEOS-4 GCM. Versions 2 and 3 of the GEOS CCM are based on the GEOS-5 GCM, which retains the "Lin-Rood" dynamical core but has a totally different set of physical parameterizatiOns to GEOS-4. In Version 2 of the GEOS CCM the Goddard stratospheric chemistry module is retained. Difference between Versions 1 and 2 thus reflect the physics changes of the underlying GCMs. Several comparisons between these two models are made, several of which reveal improvements in Version 2 (including a more realistic representation of the interannual variability of the Antarctic vortex). In Version 3 of the GEOS CCM, the stratospheric chemistry mechanism is replaced by the "GMI COMBO" code that includes tropospheric chemistry and different computational approaches. An advantage of this model version. is the reduction of high ozone biases that prevail at low chlorine loadings in Versions 1 and 2. This poster will compare and contrast various aspects of the three model versions that are relevant for understanding interactions between ozone and climate.

Immunomodulatory/inflammatory effects of geopropolis produced by Melipona fasciculata Smith in combination with doxorubicin on THP-1 cells.

PubMed

Oliveira, Lucas Pires Garcia; Conte, Fernanda Lopes; Cardoso, Eliza de Oliveira; Conti, Bruno José; Santiago, Karina Basso; Golim, Marjorie de Assis; Cruz, Maria Teresa; Sforcin, José Maurício

2016-12-01

Geopropolis (GEO) in combination with doxorubicin (DOX) reduced HEp-2 cells viability compared to GEO and DOX alone. A possible effect of this combination on the innate immunity could take place, and its effects were analysed on THP-1 cell - a human leukaemia monocytic cell line used as a model to study monocyte activity and macrophage activity, assessing cell viability, expression of cell markers and cytokine production. THP-1 cells were incubated with GEO, DOX and their combination. Cell viability was assessed by MTT assay, cell markers expression by flow cytometry and cytokine production by ELISA. GEO + DOX did not affect cell viability. GEO alone or in combination increased TLR-4 and CD80 but not HLA-DR and TLR-2 expression. GEO stimulated TNF-α production while DOX alone or in combination did not affect it. GEO alone or in combination inhibited IL-6 production. GEO exerted a pro-inflammatory profile by increasing TLR-4 and CD80 expression and TNF-α production, favouring the activation of the immune/inflammatory response. GEO + DOX did not affect cell viability and presented an immunomodulatory action. Lower concentrations of DOX combined to GEO could be used in cancer patients, avoiding side effects and benefiting from the biological properties of GEO. © 2016 Royal Pharmaceutical Society.

Homodyne BPSK-based optical inter-satellite communication links

NASA Astrophysics Data System (ADS)

Lange, Robert; Smutny, Berry

2007-02-01

Summer 2007, Tesat will verify laser communication terminals based on homodyne BPSK (binary phase shift keying) in-orbit. A 5.625 Gbps LEO-LEO laser communication link, established between the German satellite TerraSAR-X and the US satellite NFIRE, shall demonstrate the performance and advantages of laser communication. End of 2006, a further program has been kicked-off to demonstrate the performance of ~2 Gbps LEO-GEO laser communication links. The link is part of a data relais from the German LEO satellite TanDEM-X via a Geo satellite to ground. The LEO-to-GEO laser commmunication link can be extended to further ~2 Gpbs GEO-GEO, and GEO-to-ground links.

PyGeoTess 0.2.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maccarthy, Jonathan K.

2016-07-28

PyGeoTess is a Python interface module to the GeoTess gridding and earth model library from Sandia National Laboratories. It provides simplified access to a subset of the GeoTess C++ library, and takes advantage of Python's interactive interpreter and inline documentation system.

Variable-Temperature Cryostat For Radiation-Damage Testing Of Germanium Detectors

NASA Technical Reports Server (NTRS)

Floyd, Samuel R.; Puc, Bernard P.

1992-01-01

Variable-temperature cryostats developed to study radiation damage to, and annealing of, germanium gamma-ray detectors. Two styles: one accommodates large single detector and one accommodates two medium-sized detectors. New cryostats allow complete testing of large-volume germanium gamma-ray detectors without breaking cryostat vacuum and removing detectors for annealing.

A novel strategy to prepare Ge@C/rGO hybrids as high-rate anode materials for lithium ion batteries

NASA Astrophysics Data System (ADS)

Wang, Bangrun; Wen, Zhaoyin; Jin, Jun; Hong, Xiaoheng; Zhang, Sanpei; Rui, Kun

2017-02-01

Germanium is considered as a promising anode material for lithium ion batteries (LIBs) due to its high-capacity. However, owing to the huge volume variation during cycling, the batteries based on germanium anodes usually show poor cyclability and inferior rate capability. Herein, we demonstrated a novel strategy to uniformly anchor the core-shell structured germanium@carbon (Ge@C) on the reduced graphene oxide (rGO) nanosheets by the strong adhesion of dopamine. In the resulting Ge@C/rGO hybrid, the amorphous carbon layer and rGO nanosheets can effectively reduce the agglomeration of germanium and provide buffer matrix for the volume change in electrochemical lithium reactions. When used as anode materials for LIBs, Ge@C/rGO hybrids deliver a reversible capacity of 1074.4 mA h g-1 at 2C after 600 cycles (with capacity retention of 96.5%) and high rate capability of 436 mA h g-1 at 20C after 200 cycles. The encouraging electrochemical performance clearly demonstrates that Ge@C/rGO hybrids could be a potential anode material with high capacity, excellent rate capability, and good cycling stability for LIBs.

Searching Neutrinoless Double Beta Decay with GERDA Phase II

NASA Astrophysics Data System (ADS)

Agostini, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Baudis, L.; Bauer, C.; Bellotti, E.; Belogurov, S.; Bettini, A.; Bezrukov, L.; Bode, T.; Brudanin, V.; Brugnera, R.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; Comellato, T.; D’Andrea, V.; Demidova, E. V.; di Marco, N.; Domula, A.; Doroshkevich, E.; Egorov, V.; Falkenstein, R.; Gangapshev, A.; Garfagnini, A.; Giordano, M.; Gooch, C.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hahne, C.; Hakenmüller, J.; Hegai, A.; Heisel, M.; Hemmer, S.; Hiller, R.; Hofmann, W.; Holl, P.; Hult, M.; Inzhechik, L. V.; Ioannucci, L.; Csáthy, J. Janicskó; Jochum, J.; Junker, M.; Kazalov, V.; Kermaidic, Y.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Kish, A.; Klimenko, A.; Kneißl, R.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Marissens, G.; Miloradovic, M.; Mingazheva, R.; Misiaszek, M.; Moseev, P.; Nemchenok, I.; Nisi, S.; Panas, K.; Pandola, L.; Pelczar, K.; Pullia, A.; Ransom, C.; Reissfelder, M.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Sala, E.; Salamida, F.; Schmitt, C.; Schneider, B.; Schreiner, J.; Schulz, O.; Schweisshelm, B.; Schwingenheuer, B.; Schönert, S.; Schütz, A.-K.; Seitz, H.; Selivanenko, O.; Shevchik, E.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Vanhoefer, L.; Vasenko, A. A.; Veresnikova, A.; von Sturm, K.; Wagner, V.; Wegmann, A.; Wester, T.; Wiesinger, C.; Wojcik, M.; Yanovich, E.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zschocke, A.; Zsigmond, A. J.; Zuber, K.; Zuzel, G.

An observation of neutrinoless double beta (0νββ) decay would allow to shed light onto the nature of neutrinos. GERDA (GERmanium Detector Array) aims to discover this process in a background-free search using 76Ge. The experiment is located at the Laboratori Nazionali del Gran Sasso (LNGS) of the Istituto Nazionale di Fisica Nucleare (INFN) in Italy. Bare, isotopically enriched, high purity germanium detectors are operated in liquid argon. GERDA follows a staged approach. In Phase II 35.6 kg of enriched germanium detectors are operated since December 2015. The application of active background rejection methods, such as a liquid argon scintillation light read-out and pulse shape discrimination of germanium detector signals, allows to reduce the background index to the intended level of 10‑3 cts/(keVṡkgṡyr). No evidence for the 0νββ decay has been found in 23.2 kgṡyr of Phase II data, and together with data from Phase I the up-to-date most stringent half-life limit for this process in 76Ge has been established, at a median sensitivity of 5.8ṡ1025yr the 90% C.L. lower limit is 8.0ṡ1025yr.

Recovery of germanium-68 from irradiated targets

DOEpatents

Phillips, Dennis R.; Jamriska, Sr., David J.; Hamilton, Virginia T.

1993-01-01

A process for selective separation of germanium-68 from proton irradiated molybdenum targets is provided and includes dissolving the molybdenum target in a hydrogen peroxide solution to form a first ion-containing solution, contacting the first ion-containing solution with a cationic resin whereby ions selected from the group consisting of molybdenum, niobium, technetium, selenium, vanadium, arsenic, germanium, zirconium and rubidium remain in a second ion-containing solution while ions selected from the group consisting of rubidium, zinc, beryllium, cobalt, iron, manganese, chromium, strontium, yttrium and zirconium are selectively adsorbed by the first resin, adjusting the pH of the second ion-containing solution to within a range of from about 0.7 to about 3.0, adjusting the soluble metal halide concentration in the second ion-containing solution to a level adapted for subsequent separation of germanium, contacting the pH-adjusted, soluble metal halide-containing second ion-containing solution with a dextran-based material whereby germanium ions are separated by the dextran-based material, and recovering the germanium from the dextran-based material, preferably by distillation.

Synthesis of Olive-Like Nitrogen-Doped Carbon with Embedded Ge Nanoparticles for Ultrahigh Stable Lithium Battery Anodes.

PubMed

Ma, Xiaomei; Zhou, Yongning; Chen, Min; Wu, Limin

2017-05-01

The development of environment-friendly and high-performance carbon materials for energy applications has remained a great challenge. Here, a novel and facile method for synthesis of olive-like nitrogen-doped carbon embedded with germanium (Ge) nanoparticles using widespread and nontoxic dopamine as carbon and nitrogen precursors is demonstrated, especially by understanding the tendency of pure GeO 2 nanoparticles forming ellipsoidal aggregation, and the chelating reaction of the catechol structure in dopamine with metal ions. The as-synthesized Ge/N-C composites show an olive-like porous carbon structure with a loading weight of as high as 68.5% Ge nanoparticles. A lithium ion battery using Ge/N-C as the anode shows 1042 mAh g -1 charge capacity after 2000 cycles (125 d) charge/discharge at C/2 (1C = 1600 mA g -1 ) with a capacity maintaining efficiency of 99.6%, significantly exceeding those of the previously reported Ge/C-based anode materials. This prominent cyclic charge/discharge performance of the Ge/N-C anode is attributed to the well-dispersed Ge nanoparticles in graphitic N-doped carbon matrix, which facilitates high rates (0.5-15 C) of charge/discharge and increases the anode structure integrity. The synthesis strategy presented here may be a very promising approach to prepare a series of active nanoparticle-carbon hybrid materials with nitrogen doping for more and important applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Germanium and InGaAs/InP SPADs for single-photon detection in the near-infrared

NASA Astrophysics Data System (ADS)

Tosi, Alberto; Dalla Mora, Alberto; Zappa, Franco; Cova, Sergio

2007-09-01

Single-Photon Avalanche Diodes (SPADs) for near-infrared (800-1700 nm) wavelengths can be manufactured both in InGaAs/InP and in germanium. Recently, new InGaAs/InP SPADs became commercially available with good overall performances, but with the intrinsic bottleneck of strong afterpulsing effect, originated in the InP multiplication layer. At present, germanium technology is not exploited for single-photon detectors, but previous devices demonstrate lower afterpulsing even at very low temperatures and promising dark count rate when employing pure manufacturing process. In this work, we compare germanium and InGaAs/InP SPADs in terms of dark counts, afterpulsing, timing jitter, and quantum efficiency. Eventually, we highlight the motivations for considering germanium as a key material for single-photon counting in the NIR.

CER_SRBAVG_Aqua-FM3-MODIS_Edition2A

Atmospheric Science Data Center

2014-07-24

... Readme Files:  Readme R4-671 UNIX C shell scripts for extracting regional CERES geo and non-geo fluxes from ... Software Files :  Read Package (C) UNIX C shell scripts for extracting regional CERES geo and non-geo fluxes from ...

CERES GEO Ed4 Available Data

Atmospheric Science Data Center

2017-10-11

... Spatial Resolution Temporal Coverage CER_GEO_Ed4_GOE08 Hourly 2-4km observation at nadir, subsampled every 8-9 km 2000-03-01 to 2003-04-01 CER_GEO_Ed4_GOE09 Hourly 2-4km observation at nadir, subsampled ...

Generator for gallium-68 and compositions obtained therefrom

DOEpatents

Neirinckx, Rudi D.; Davis, Michael A.

1981-01-01

A generator for obtaining radioactive gallium-68 from germanium-68 bound in a resin containing unsubstituted phenolic hydroxyl groups. The germanium-68 is loaded into the resin from an aqueous solution of the germanium-68. A physiologically acceptable solution of gallium-68 having an activity of 0.1 to 50 millicuries per milliliter of gallium-68 solution is obtained. The solution is obtained from the bound germanium-68 which forms gallium-68 in situ by eluting the column with a hydrochloric acid solution to form an acidic solution of gallium-68. The acidic solution of gallium-68 can be neutralized.

Five-Year (2004-2009)Observations of Upper Tropospheric Water Vapor and Cloud Ice from MLS and Comparisons with GEOS-5 Analyses

NASA Technical Reports Server (NTRS)

Jiang, Jonathan H.; Su, Hui; Pawson, Steven; Liu, Hui-Chun; Read, William; Waters, Joe W.; Santee, Michelle; Wu, Dong L.; Schwartz, Michael; Lambert, Alyn;

Ultra compact 45 GHz CMOS compatible Germanium waveguide photodiode with low dark current.

PubMed

DeRose, Christopher T; Trotter, Douglas C; Zortman, William A; Starbuck, Andrew L; Fisher, Moz; Watts, Michael R; Davids, Paul S

2011-12-05

We present a compact 1.3 × 4 μm2 Germanium waveguide photodiode, integrated in a CMOS compatible silicon photonics process flow. This photodiode has a best-in-class 3 dB cutoff frequency of 45 GHz, responsivity of 0.8 A/W and dark current of 3 nA. The low intrinsic capacitance of this device may enable the elimination of transimpedance amplifiers in future optical data communication receivers, creating ultra low power consumption optical communications.

Glass Polyalkenoate Cements Designed for Cranioplasty Applications: An Evaluation of Their Physical and Mechanical Properties

PubMed Central

Khader, Basel A.; Curran, Declan J.; Peel, Sean; Towler, Mark R.

2016-01-01

Glass polyalkenoate cements (GPCs) have potential for skeletal cementation. Unfortunately, commercial GPCs all contain, and subsequently release, aluminum ions, which have been implicated in degenerative brain disease. The purpose of this research was to create a series of aluminum-free GPCs constructed from silicate (SiO2), calcium (CaO), zinc (ZnO) and sodium (Na2O)-containing glasses mixed with poly-acrylic acid (PAA) and to evaluate the potential of these cements for cranioplasty applications. Three glasses were formulated based on the SiO2-CaO-ZnO-Na2O parent glass (KBT01) with 0.03 mol % (KBT02) and 0.06 mol % (KBT03) germanium (GeO2) substituted for ZnO. Each glass was then mixed with 50 wt % of a patented SiO2-CaO-ZnO-strontium (SrO) glass composition and the resultant mixtures were subsequently reacted with aqueous PAA (50 wt % addition) to produce three GPCs. The incorporation of Ge in the glass phase was found to result in decreased working (142 s to 112 s) and setting (807 s to 448 s) times for the cements manufactured from them, likely due to the increase in crosslink formation between the Ge-containing glasses and the PAA. Compressive (σc) and biaxial flexural (σf) strengths of the cements were examined at 1, 7 and 30 days post mixing and were found to increase with both maturation and Ge content. The bonding strength of a titanium cylinder (Ti) attached to bone by the cements increased from 0.2 MPa, when placed, to 0.6 MPa, after 14 days maturation. The results of this research indicate that Germano-Silicate based GPCs have suitable handling and mechanical properties for cranioplasty fixation. PMID:27023623

Study of the effect of doping on the temperature stability of the optical properties of germanium single crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Podkopaev, O. I.; Shimanskiy, A. F., E-mail: shimanaf@mail.ru; Kopytkova, S. A.

2016-10-15

The effect of doping on the optical transmittance of germanium single crystals is studied by infrared Fourier spectroscopy. It is established that the introduction of silicon and tellurium additives into germanium doped with antimony provides a means for improving the temperature stability of the optical properties of the crystals.

Mineral resource of the month: germanium

USGS Publications Warehouse

Jorgenson, John D.

2003-01-01

Germanium is a hard, brittle semimetal that first came into use over a half-century ago as a semiconductor material in radar units and in the first transistor ever made. Most germanium is recovered as a byproduct of zinc smelting, but it has also been recovered at some copper smelters and from the fly ash of coal-burning industrial power plants.

Naturally occurring vapor-liquid-solid (VLS) Whisker growth of germanium sulfide

USGS Publications Warehouse

Finkelman, R.B.; Larson, R.R.; Dwornik, E.J.

1974-01-01

The first naturally occurring terrestrial example of vapor-liquid-solid (VLS) growth has been observed in condensates from gases released by burning coal in culm banks. Scanning electron microscopy, X-ray diffraction, and energy dispersive analysis indicate that the crystals consist of elongated rods (??? 100 ??m) of germanium sulfide capped by bulbs depleted in germanium. ?? 1974.

Highly Stable Bonding of Thiol Monolayers to Hydrogen-Terminated Si via Supercritical Carbon Dioxide: Toward a Super Hydrophobic and Bioresistant Surface.

PubMed

Bhartia, Bhavesh; Puniredd, Sreenivasa Reddy; Jayaraman, Sundaramurthy; Gandhimathi, Chinnasamy; Sharma, Mohit; Kuo, Yen-Chien; Chen, Chia-Hao; Reddy, Venugopal Jayarama; Troadec, Cedric; Srinivasan, Madapusi Palavedu

2016-09-21

Oxide-free silicon chemistry has been widely studied using wet-chemistry methods, but for emerging applications such as molecular electronics on silicon, nanowire-based sensors, and biochips, these methods may not be suitable as they can give rise to defects due to surface contamination, residual solvents, which in turn can affect the grafted monolayer devices for practical applications. Therefore, there is a need for a cleaner, reproducible, scalable, and environmentally benign monolayer grafting process. In this work, monolayers of alkylthiols were deposited on oxide-free semiconductor surfaces using supercritical carbon dioxide (SCCO2) as a carrier fluid owing to its favorable physical properties. The identity of grafted monolayers was monitored with Fourier transform infrared (FTIR) spectroscopy, high-resolution X-ray photoelectron spectroscopy (HRXPS), XPS, atomic force microscopy (AFM), contact angle measurements, and ellipsometry. Monolayers on oxide-free silicon were able to passivate the surface for more than 50 days (10 times than the conventional methods) without any oxide formation in ambient atmosphere. Application of the SCCO2 process was further extended by depositing alkylthiol monolayers on fragile and brittle 1D silicon nanowires (SiNWs) and 2D germanium substrates. With the recent interest in SiNWs for biological applications, the thiol-passivated oxide-free silicon nanowire surfaces were also studied for their biological response. Alkylthiol-functionalized SiNWs showed a significant decrease in cell proliferation owing to their superhydrophobicity combined with the rough surface morphology. Furthermore, tribological studies showed a sharp decrease in the coefficient of friction, which was found to be dependent on the alkyl chain length and surface bond. These studies can be used for the development of cost-effective and highly stable monolayers for practical applications such as solar cells, biosensors, molecular electronics, micro- and nano- electromechanical systems, antifouling agents, and drug delivery.

High-temperature specific heat of Bi2GeO5 and SmBiGeO5 compounds

NASA Astrophysics Data System (ADS)

Denisova, L. T.; Belousova, N. V.; Galiakhmetova, N. A.; Denisov, V. M.; Zhereb, V. P.

2017-08-01

The SmBiGeO5 compound is synthesized from Sm2O3, Bi2O3, and GeO2 by solid-state synthesis with subsequent annealing at 1003, 1073, 1123, 1143, 1173, and 1223 K. The metastable Bi2GeO5 compound is prepared from melt. Temperature dependences of specific heat of Bi2GeO5 (350-1000 K) and SmBiGeO5 (370-1000 K) are measured by differential scanning calorimetry. Basing on the experimental dependences C P = f( T), the thermodynamic functions of the oxide compounds are calculated.

The time and temperature dependence of the thermoelectric properties of silicon-germanium alloy

NASA Technical Reports Server (NTRS)

Raag, V.

1975-01-01

Experimental data on the electrical resistivity and Seebeck coefficient of n-type and p-type silicon-germanium alloys are analyzed in terms of a solid-state dopant precipitation model proposed by Lifshitz and Slyozov (1961). Experimental findings on the time and temperature dependence of the thermal conductivity of these two types of alloy indicate that the thermal conductivity of silicon-germanium alloys changes with time, contrary to previous hypothesis. A preliminary model is presented which stipulates that the observed thermal conductivity decrease in silicon-germanium alloys is due partly to dopant precipitation underlying the electrical property changes and partly to enhanced alloying of the material. It is significant that all three properties asymptotically approach equilibrium values with time. Total characterization of these properties will enable the time change to be fully compensated in the design of a thermoelectric device employing silicon-germanium alloys.

Self-assembled asymmetric membrane containing micron-size germanium for high capacity lithium ion batteries

DOE PAGES

Byrd, Ian; Chen, Hao; Webber, Theron; ...

2015-10-23

We report the formation of novel asymmetric membrane electrode containing micron-size (~5 μm) germanium powders through a self-assembly phase inversion method for high capacity lithium ion battery anode. 850 mA h g -1 capacity (70%) can be retained at a current density of 600 mA g -1 after 100 cycles with excellent rate performance. Such a high retention rate has rarely been seen for pristine micron-size germanium anodes. Moreover, scanning electron microscope studies reveal that germanium powders are uniformly embedded in a networking porous structure consisting of both nanopores and macropores. It is believed that such a unique porous structuremore » can efficiently accommodate the ~260% volume change during germanium alloying and de-alloying process, resulting in an enhanced cycling performance. Finally, these porous membrane electrodes can be manufactured in large scale using a roll-to-roll processing method.« less

Removal and deposition efficiencies of the long-lived 222Rn daughters during etching of germanium surfaces

NASA Astrophysics Data System (ADS)

Zuzel, G.; Wójcik, M.; Majorovits, B.; Lampert, M. O.; Wendling, P.

2012-06-01

Removal and deposition efficiencies of the long-lived 222Rn daughters during etching from and onto surfaces of standard and high purity germanium were investigated. The standard etching procedure of Canberra-France used during production of high purity n-type germanium diodes was applied to germanium discs, which have been exposed earlier to a strong radon source for deposition of its progenies. An uncontaminated sample was etched in a solution containing 210Pb, 210Bi and 210Po. All isotopes were measured before and after etching with appropriate detectors. In contrast to copper and stainless steel, they were removed from germanium very efficiently. However, the reverse process was also observed. Considerable amounts of radioactive lead, bismuth and polonium isotopes present initially in the artificially polluted etchant were transferred to the clean high purity surface during processing of the sample.

U(VI) uranyl cation-cation interactions in framework germanates.

PubMed

Morrison, Jessica M; Moore-Shay, Laura J; Burns, Peter C

2011-03-21

The isomorphous compounds NH(4)[(UO(6))(2)(UO(2))(9)(GeO(4))(GeO(3)(OH))] (1), K[(UO(6))(2)(UO(2))(9)(GeO(4))(GeO(3)(OH))] (2), Li(3)O[(UO(6))(2)(UO(2))(9)(GeO(4))(GeO(3)(OH))] (3), and Ba[(UO(6))(2)(UO(2))(9)(GeO(4))(2)] (4) were synthesized by hydrothermal reaction at 220 °C. The structures were determined using single crystal X-ray diffraction and refined to R(1) = 0.0349 (1), 0.0232 (2), 0.0236 (3), 0.0267 (4). Each are trigonal, P(3)1c. 1: a = 10.2525(5), c = 17.3972(13), V = 1583.69(16) Å(3), Z = 2; 2: a = 10.226(4), c = 17.150(9), V = 1553.1(12) Å(3), Z = 2; 3: a = 10.2668(5), c = 17.0558(11), V = 1556.94(15) Å(3), Z = 2; 4: a = 10.2012(5), c = 17.1570(12), V = 1546.23(15) Å(3), Z = 2. There are three symmetrically independent U sites in each structure, two of which correspond to typical (UO(2))(2+) uranyl ions and the other of which is octahedrally coordinated by six O atoms. One of the uranyl ions donates a cation-cation interaction, and accepts a different cation-cation interaction. The linkages between the U-centered polyhedra result in a relatively dense three-dimensional framework. Ge and low-valence sites are located within cavities in the framework of U-polyhedra. Chemical, thermal, and spectroscopic characterizations are provided.

Immobilization of MSWI fly ash through geopolymerization: effects of water-wash.

PubMed

Zheng, Lei; Wang, Chengwen; Wang, Wei; Shi, Yunchun; Gao, Xingbao

2011-02-01

The present research explored the role played by water-wash on geopolymerization for the immobilization and solidification of municipal solid waste incineration (MSWI) fly ash. The water-wash pretreatment substantially promoted the early strength of geopolymer and resulted in a higher ultimate strength compared to the counterpart without water-wash. XRD pattern of water-washed fly ash (WFA) revealed that NaCl and KCl were nearly eliminated in the WFA. Aside from geopolymer, ettringite (Ca(6)Al(2)(SO(4))(3)(OH)(12)·26H(2)O) was formed in MSWI fly ash-based geopolymer (Geo-FA). Meanwhile, calcium aluminate hydrate (Ca(2)Al(OH)(7)·3H(2)O), not ettringite, appeared in geopolymer that was synthesized with water-washed fly ash (Geo-WFA). Leached Geo-WFA (Geo-WFA-L) did not exhibit any signs of deterioration, while there was visual cracking on the surface of leached Geo-FA (Geo-FA-L). The crack may be caused by the migration of K(+), Na(+), and Cl(-) ions outside Geo-FA and the negative effect from crystallization of expansive compounds can not be excluded. Furthermore, transformation of calcium aluminate hydrate in Geo-WFA to ettringite in Geo-WFA-L allowed the reduction of the pore size of the specimen. IR spectrums suggested that Geo-WFA can supply more stable chemical encapsulation for heavy metals. Static monolithic leaching tests were conducted for geopolymers to estimate the immobilization efficiency. Heavy metal leaching was elucidated using the first-order reaction/diffusion model. Combined with the results from compressive strength and microstructure of samples, the effects of water-wash on immobilization were inferred in this study. Copyright © 2010 Elsevier Ltd. All rights reserved.

Fast preparation of flower-like Bi{sub 4}Ge{sub 3}O{sub 12} microstructures via a microwave-assisted hydrothermal process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Zhao-Qian; Zhang, Lei; Chen, Xue-Tai, E-mail: xtchen@netra.nju.edu.cn

In the present paper, we report a facile and fast microwave-assisted solution-phase approach for the preparation of flower-like bismuth germanate (Bi{sub 4}Ge{sub 3}O{sub 12}) microstructures, employing bismuth nitrate pentahydrate (Bi(NO{sub 3}){sub 3}{center_dot}5H{sub 2}O) and germanium dioxide (GeO{sub 2}) as starting materials. The phase and morphology of the products were characterized by powder X-ray diffraction, X-ray photoelectron spectrum, energy dispersive spectrometry, and scanning electron microscopy. Some control experiments have been carried out to reveal the influencing factors involved in the formation, which suggested that reaction time, reaction temperature, the volume of ammonia and glycerol play crucial roles in the formation ofmore » the flower-like Bi{sub 4}Ge{sub 3}O{sub 12}. The optical absorption property of the product has been investigated. - Highlights: Black-Right-Pointing-Pointer Flower-like Bi4Ge3O12 was synthesized via a microwave-assisted solution route. Black-Right-Pointing-Pointer The phases and morphologies of the product have been characterized. Black-Right-Pointing-Pointer The optical property of the product has been studied.« less

Fabrication of MTN-type zeolite by self-assembling of supramolecular compound

NASA Astrophysics Data System (ADS)

Huang, Aisheng; Caro, Jürgen

2009-10-01

MTN-type (Zeolite Socony Mobil Thirty-Nine) zeolite was prepared at 473 K by a novel method through self-assembling of a supramolecular compound called 2,4,6-tris (4-pyridyl) triazine (TPT) in DMF (N,N-dimethylformamide). The effects of fluoride, DMF and germanium on the synthesis of MTN-type zeolite were investigated. The crystallization was facilitated by adding fluoride to the synthesis solution, resulting in the formation of highly crystalline MTN samples, while some amorphous phase was observed in fluoride-free batches. DMF was required to obtain a highly crystalline MTN sample, since TPT dissolves easier in DMF than in water, thus facilitating the self-assembling of TPT into a 3D network to structure the MTN framework. The MTN structure could be synthesized at low germanium content (Ge/Si≤0.18), while AST (AlPO 4-sixteen) as a foreign phase is formed at high germanium substitution (Ge/Si≥0.5).

Rapid Solid-State Metathesis Routes to Nanostructured Silicon-Germainum

NASA Technical Reports Server (NTRS)

Rodriguez, Marc (Inventor); Kaner, Richard B. (Inventor); Bux, Sabah K. (Inventor); Fleurial, Jean-Pierre (Inventor)

2014-01-01

Methods for producing nanostructured silicon and silicon-germanium via solid state metathesis (SSM). The method of forming nanostructured silicon comprises the steps of combining a stoichiometric mixture of silicon tetraiodide (SiI4) and an alkaline earth metal silicide into a homogeneous powder, and initating the reaction between the silicon tetraiodide (SiI4) with the alkaline earth metal silicide. The method of forming nanostructured silicon-germanium comprises the steps of combining a stoichiometric mixture of silicon tetraiodide (SiI4) and a germanium based precursor into a homogeneous powder, and initiating the reaction between the silicon tetraiodide (SiI4) with the germanium based precursors.

Applied Astronomy: An Optical Survey for Space Debris at GEO

NASA Technical Reports Server (NTRS)

Seitzer, Patrick; Barker, Edwin S.; Abercromby, K.; Rodriquez, H.

2007-01-01

A viewgraph is presented to discuss space debris at Geosynchronous Earth Orbit (GEO). The topics include: 1) Syncom1 launched February 14, 1963 Failed on orbit insertion 1st piece of GEO debris!; 2) Example of recent GEO payload: XM-2 Rock satellite for direct broadcast radio; 3) MODEST Michigan Orbital DEbrisSurvey Telescope the telescope formerly known as the Curtis-Schmidt; 4) GEO Debris Survey; 5) Examples of Detections; 6) Brightness Variations Common; 7) Observed Angular Rates; 8) Two Populations at GEO; 9) High Area-to-Mass Ratio Material (A/M); 10) Examples of MLI; 11) Examples of MLI Release in LEO; 12) Liou & Weaver (2005) models; 13) ESA 1-m Telescope Survey; 14) Two Telescopes March 2007 Survey and Follow-up; 15) Final Eccentricity; and 16) How control Space Debris?

Combinatorial effects of geopropolis produced by Melipona fasciculata Smith with anticancer drugs against human laryngeal epidermoid carcinoma (HEp-2) cells.

PubMed

Bartolomeu, Ariane Rocha; Frión-Herrera, Yahima; da Silva, Livia Matsumoto; Romagnoli, Graziela Gorete; de Oliveira, Deilson Elgui; Sforcin, José Maurício

2016-07-01

The identification of natural products exerting a combined effect with therapeutic agents could be an alternative for cancer treatment, reducing the concentration of the drugs and side effects. Geopropolis (Geo) is produced by some stingless bees from a mixture of vegetable resins, gland secretions of the bees and soil. It has been used popularly as an antiseptic agent and to treat respiratory diseases and dermatosis. To determine whether Geo enhances the anticancer effect of carboplatin, methotrexate and doxorubicin (DOX), human laryngeal epidermoid carcinoma (HEp-2) cells were treated with Geo alone or in combination with each drug. Cell growth, cytotoxicity and apoptosis were evaluated using 3-(4,5-dimethyl thiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay, lactate dehydrogenase (LDH) release, and flow cytometry. Scratch assay was used to analyze cell migration and transmission electron microscopy to observe morphologic alterations. The influence of Geo on drug resistance was also investigated assessing P-glycoprotein (P-gp) action. Geo inhibited cell proliferation and migration. The combination Geo+DOX led to the highest cytotoxic activity and induced apoptosis, leading to loss of membrane integrity. Geo had no effect on P-gp-mediated efflux of DOX. Data indicate that Geo combined with DOX could be a potential clinical chemotherapeutic approach for laryngeal cancer treatment. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Nonstoichiometric La(2 - x)GeO(5 - delta) monoclinic oxide as a new fast oxide ion conductor.

PubMed

Ishihara, T; Arikawa, H; Akbay, T; Nishiguchi, H; Takita, Y

2001-01-17

Oxide ion conductivity in La(2)GeO(5)-based oxide was investigated and it was found that La-deficient La(2)GeO(5) exhibits oxide ion conductivity over a wide range of oxygen partial pressure. The crystal structure of La(2)GeO(5) was estimated to be monoclinic with P2(1)/c space group. Conductivity increased with increasing the amount of La deficiency and the maximum value was attained at x = 0.39 in La(2 - x)GeO(5 - delta). The oxide ion transport number in La(2)GeO(5)-based oxide was estimated to be unity by the electromotive force measurement in H(2)-O(2) and N(2)-O(2) gas concentration cells. At a temperature higher than 1000 K, the oxide ion conductivity of La(1.61)GeO(5 - delta) was almost the same as that of La(0.9)Sr(0.1)Ga(0.8)Mg(0.2)O(3 - delta) or Ce(0.85)Gd(0.15)O(2 - delta), which are well-known fast oxide ion conductors. On the other hand, a change in the activation energy for oxide ion conductivity was observed at 973 K, and at intermediate temperature, the oxide ion conductivity of La(1.61)GeO(5 - delta) became much smaller than that of these well-known fast oxide ion conductors. The change in the activation energy of the oxide ion conductivity seems to be caused by a change in the local oxygen vacancy structure. However, doping a small amount of Sr for La in La(2)GeO(5) was effective to stabilize the high-temperature crystal structure to low temperature. Consequently, doping a small amount of Sr increases the oxide ion conductivity of La(2)GeO(5)-based oxide at low temperature.

SiGe-on-insulator fabricated via germanium condensation following high-fluence Ge+ ion implantation

NASA Astrophysics Data System (ADS)

Anthony, R.; Haddara, Y. M.; Crowe, I. F.; Knights, A. P.

2017-08-01

Germanium condensation is demonstrated using a two-step wet oxidation of germanium implanted Silicon-On-Insulator (SOI). Samples of 220 nm thick SOI are implanted with a nominal fluence of 5 × 1016 cm-2 Ge+ at an energy of 33 keV. Primary post-implantation wet oxidation is performed initially at 870 °C for 70 min, with the aim of capping the sample without causing significant dose loss via Ge evaporation through the sample surface. This is followed by a secondary higher temperature wet oxidation at either 900 °C, 1000 °C, or 1080 °C. The germanium retained dose and concentration profile, and the oxide thickness is examined after primary oxidation, and various secondary oxidation times, using Rutherford backscattering analysis. A mixed SiGe oxide is observed to form during the primary oxidation followed by a pure silicon oxide after higher temperature secondary oxidation. The peak germanium concentration, which varies with secondary oxidation condition, is found to range from 43 at. % to 95 at. %, while the FWHM of the Ge profile varies from 13 to 5 nm, respectively. It is also observed that both the diffusion of germanium and the rate of oxidation are enhanced at 870 and 900 °C compared to equilibrium expectations. Transmission electron microscopy of a representative sample with secondary oxidation at 1080 °C for 20 min shows that the SiGe layer is crystalline in nature and seeded from the underlying silicon. Raman spectroscopy is used to determine residual strain in the SiGe region following secondary oxidation. The strain is compressive in nature and increases with Ge concentration to a maximum of approximately 1% in the samples probed. In order to elucidate the physical mechanisms, which govern the implantation-condensation process, we fit the experimental profiles of the samples with a model that uses a modified segregation boundary condition; a modified linear rate constant for the oxidation; and an enhanced diffusion coefficient of germanium where the enhancement is inversely proportional to the temperature and decays with increasing time. Comparison of the modeled and experimental results shows reasonable agreement and allows conclusions to be made regarding the dominant physical mechanisms, despite the semi-empirical nature of the model used.

Evaluation of NASA GEOS-ADAS Modeled Diurnal Warming Through Comparisons to SEVIRI and AMSR2 SST Observations

NASA Astrophysics Data System (ADS)

Gentemann, C. L.; Akella, S.

2018-02-01

An analysis of the ocean skin Sea Surface Temperature (SST) has been included in the Goddard Earth Observing System (GEOS) - Atmospheric Data Assimilation System (ADAS), Version 5 (GEOS-ADAS). This analysis is based on the GEOS atmospheric general circulation model (AGCM) that simulates near-surface diurnal warming and cool skin effects. Analysis for the skin SST is performed along with the atmospheric state, including Advanced Very High Resolution Radiometer (AVHRR) satellite radiance observations as part of the data assimilation system. One month (September, 2015) of GEOS-ADAS SSTs were compared to collocated satellite Spinning Enhanced Visible and InfraRed Imager (SEVIRI) and Advanced Microwave Scanning Radiometer 2 (AMSR2) SSTs to examine how the GEOS-ADAS diurnal warming compares to the satellite measured warming. The spatial distribution of warming compares well to the satellite observed distributions. Specific diurnal events are analyzed to examine variability within a single day. The dependence of diurnal warming on wind speed, time of day, and daily average insolation is also examined. Overall the magnitude of GEOS-ADAS warming is similar to the warming inferred from satellite retrievals, but several weaknesses in the GEOS-AGCM simulated diurnal warming are identified and directly related back to specific features in the formulation of the diurnal warming model.

Inducing tunable host luminescence in Zn2GeO4 tetrahedral materials via doping Cr3+

NASA Astrophysics Data System (ADS)

Bai, Qiongyu; Li, Panlai; Wang, Zhijun; Xu, Shuchao; Li, Ting; Yang, Zhiping; Xu, Zheng

2018-06-01

Zn2GeO4 consisting of tetrahedron, and it is a self-luminescent material due to the presence of the native defects and shows a bluish white emission excited by ultraviolet. Although Cr3+ doped in a tetrahedron generally cannot show luminescence, in this research, new defects are formed as Cr3+ doped in Zn2GeO4, hence a green emission band can be obtained. Meanwhile, the intensity of host emission is also decreased. Therefore, Zn2GeO4:Cr3+ are synthesized using a high-temperature solid-phase method. Thermoluminescence (TL) and luminescence decay curves are used to investigate the variation of native defects. The emission colour can be tuned from bluish white to green when Cr3+ doped in Zn2GeO4. This result has guidance for controlling the native emission of self-luminescent material.

Experience from operating germanium detectors in GERDA

NASA Astrophysics Data System (ADS)

Palioselitis, Dimitrios; GERDA Collaboration

2015-05-01

Phase I of the Germanium Detector Array (GERDA) experiment, searching for the neutrinoless double beta (0νββ) decay of 76Ge, was completed in September 2013. The most competitive half-life lower limit for the 0νββ decay of 76Ge was set (T-0ν1/2 > 2.1 · 1025 yr at 90% C.L.). GERDA operates bare Ge diodes immersed in liquid argon. During Phase I, mainly refurbished semi-coaxial high purity Ge detectors from previous experiments were used. The experience gained with handling and operating bare Ge diodes in liquid argon, as well as the stability and performance of the detectors during GERDA Phase I are presented. Thirty additional new enriched BEGe-type detectors were produced and will be used in Phase II. A subgroup of these detectors has already been used successfully in GERDA Phase I. The present paper gives an overview of the production chain of the new germanium detectors, the steps taken to minimise the exposure to cosmic radiation during manufacturing, and the first results of characterisation measurements in vacuum cryostats.

XAFS and XEOL of tetramesityldigermene - An electronic structure study of a heavy group 14 ethylene analogue

NASA Astrophysics Data System (ADS)

Ward, Matthew J.; Rupar, Paul A.; Murphy, Michael W.; Yiu, Yun-Mui; Baines, Kim M.; Sham, Tsun-Kong

2013-04-01

Digermene, the germanium analogue of ethylene, has a multiple bonding motif that differs greatly from that of alkenes and exhibits no pure σ or π type bonds. The electronic structure of digermenes is difficult to study experimentally due to their reactivity, and is computationally challenging because of their shallow potential energy surfaces. Using X-ray absorption near edge structures at both the germanium K and L edges we have been able to directly probe the unoccupied electronic states, or the lowest unoccupied molecular orbital (LUMO), and LUMO+ etc. in the Ge=Ge bond of tetramesityldigermene. We have demonstrated that the LUMO, LUMO+, etc. are composed of hybrid Ge 4s and 4p orbitals. Additionally, our data suggest that the LUMO exhibits relatively more Ge 4s character, whereas the LUMO+ and LUMO+2 exhibit relatively more Ge 4p character. An X-ray excited optical luminescence study of Ge2Mes4 revealed one broad optical emission band at 620 nm, which is significantly red shifted compared to the known energy gap of this molecular germanium compound.

The biocorrosion of copper by biopolymers as examined in situ, in real time FT-IR/CIR/ATR in conjunction with pre and post XPS/AES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gianotto, A.K.; Wichlacz, P.L.; Jolley, J.G.

1989-01-01

Thin films of copper (2.0 nm on germanium internal reflection elements (IREs) and 3.4 nm on germanium discs) were exposed to 10% gum arabic (aqueous solution), 2% alginic acid (aqueous solution), 1% bacterial culture supernatant (BCS, simulated seawater solution) and 0.5% Pseudomonas atlantica exopolymer (simulated seawater solution). The IREs were monitored in situ, in real time using fourier transform infrared/cylindrical internal reflection/attenuated total reflection spectroscopy as a function of time at ambient conditions. The discs were characterized (pre- and post-exposure) by x-ray photoelectron and Auger electron spectroscopies. Ancillary graphite furnace atomic absorption spectroscopy was used to monitor the removal processmore » of the copper thin film from the germanium substrates. Results indicate that Cu was oxidized by gum arabic, alginic acid and BCS. Furthermore, Cu was removed from the Cu/Ge interface by all four polymers. The Cu was found associated with the polymer solutions. 20 refs., 6 figs., 1 tab.« less

Atomic structure of a metal-supported two-dimensional germania film

NASA Astrophysics Data System (ADS)

Lewandowski, Adrián Leandro; Schlexer, Philomena; Büchner, Christin; Davis, Earl M.; Burrall, Hannah; Burson, Kristen M.; Schneider, Wolf-Dieter; Heyde, Markus; Pacchioni, Gianfranco; Freund, Hans-Joachim

2018-03-01

The growth and microscopic characterization of two-dimensional germania films is presented. Germanium oxide monolayer films were grown on Ru(0001) by physical vapor deposition and subsequent annealing in oxygen. We obtain a comprehensive image of the germania film structure by combining intensity-voltage low-energy electron diffraction (I/V-LEED) and ab initio density functional theory (DFT) analysis with atomic-resolution scanning tunneling microscopy (STM) imaging. For benchmarking purposes, the bare Ru(0001) substrate and the (2 ×2 )3 O covered Ru(0001) were analyzed with I/V-LEED with respect to previous reports. STM topographic images of the germania film reveal a hexagonal network where the oxygen and germanium atom positions appear in different imaging contrasts. For quantitative LEED, the best agreement has been achieved with DFT structures where the germanium atoms are located preferentially on the top and fcc hollow sites of the Ru(0001) substrate. Moreover, in these atomically flat germania films, local site geometries, i.e., tetrahedral building blocks, ring structures, and domain boundaries, have been identified, indicating possible pathways towards two-dimensional amorphous networks.

Results on neutrinoless double beta decay of 76Ge from GERDA Phase I

NASA Astrophysics Data System (ADS)

Palioselitis, Dimitrios; GERDA Collaboration

2015-05-01

The Germanium Detector Array (GERDA) experiment is searching for the neutrinoless double beta (0νββ) decay of 76Ge by operating bare germanium diodes in liquid argon. GERDA is located at the Gran Sasso National Laboratory (LNGS) in Italy. During Phase I, a total exposure of 21.6 kg yrand a background index of 0.01 cts/(keVkg yr) were reached. No signal was observed and a lower limit of T0ν1/2 > 2.1 · 1025 yr(90% C.L.) is derived for the half life of the 0νββ decay of 76Ge.

Low temperature mobility in hafnium-oxide gated germanium p-channel metal-oxide-semiconductor field-effect transistors

NASA Astrophysics Data System (ADS)

Beer, Chris; Whall, Terry; Parker, Evan; Leadley, David; De Jaeger, Brice; Nicholas, Gareth; Zimmerman, Paul; Meuris, Marc; Szostak, Slawomir; Gluszko, Grzegorz; Lukasiak, Lidia

2007-12-01

Effective mobility measurements have been made at 4.2K on high performance high-k gated germanium p-type metal-oxide-semiconductor field effect transistors with a range of Ge/gate dielectric interface state densities. The mobility is successfully modelled by assuming surface roughness and interface charge scattering at the SiO2 interlayer/Ge interface. The deduced interface charge density is approximately equal to the values obtained from the threshold voltage and subthreshold slope measurements on each device. A hydrogen anneal reduces both the interface state density and the surface root mean square roughness by 20%.

Oriented bottom-up growth of armchair graphene nanoribbons on germanium

DOEpatents

Arnold, Michael Scott; Jacobberger, Robert Michael

2016-03-15

Graphene nanoribbon arrays, methods of growing graphene nanoribbon arrays and electronic and photonic devices incorporating the graphene nanoribbon arrays are provided. The graphene nanoribbons in the arrays are formed using a scalable, bottom-up, chemical vapor deposition (CVD) technique in which the (001) facet of the germanium is used to orient the graphene nanoribbon crystals along the [110] directions of the germanium.

Density Functional Theory Calculations Revealing Metal-like Band Structures for Ultrathin Ge {111} and {211} Surface Layers.

PubMed

Tan, Chih-Shan; Huang, Michael Hsuan-Yi

2018-05-21

To find out if germanium should also possess facet-dependent electrical conductivity properties, surface state density functional theory (DFT) calculations were performed on 1-6 layers of Ge (100), (110), (111), and (211) planes. Tunable Ge (100) and (110) planes always present the same semiconducting band structure with a band gap of 0.67 eV expected of bulk germanium. In contrast, 1, 2, 4, and 5 layers of Ge (111) and (211) plane models show metal-like band structures with continuous density of states (DOS) throughout the entire band. For 3 and 6 layers of Ge (111) and (211) plane models, the normal semiconducting band structure was obtained. The plane layers with metal-like band structures also show Ge-Ge bond length deviations and bond distortions, as well as significantly different 4s and 4p frontier orbital electron count and their relative percentages integrated over the valence and conduction bands from those of the semiconducting state. These differences should contribute to strikingly dissimilar band structures. The calculation results suggest observation of facet-dependent electrical conductivity properties of germanium materials, and transistors made of germanium may also need to consider the facet effects with shrinking dimensions approaching 3 nm. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Framework 'interstitial' oxygen in La(10)(GeO(4))(5-)(GeO(5))O(2) apatite electrolyte.

PubMed

Pramana, Stevin S; Klooster, Wim T; White, T J

2007-08-01

Oxygen conduction at low temperatures in apatites make these materials potentially useful as electrolytes in solid-oxide fuel cells, but our understanding of the defect structures enabling ion migration is incomplete. While conduction along [001] channels is dominant, considerable inter-tunnel mobility has been recognized. Using neutron powder diffraction of stoichiometric 'La(10)(GeO(4))(6)O(3)', it has been shown that this compound is more correctly described as an La(10)(GeO(4))(5-)(GeO(5))O(2) apatite, in which high concentrations of interstitial oxygen reside within the channel walls. It is suggested that these framework interstitial O atoms provide a reservoir of ions that can migrate into the conducting channels of apatite, via a mechanism of inter-tunnel oxygen diffusion that transiently converts GeO(4) tetrahedra to GeO(5) distorted trigonal bipyramids. This structural modification is consistent with known crystal chemistry and may occur generally in oxide apatites.

Mode coupling in 340 μm GeO2 doped core-silica clad optical fibers

NASA Astrophysics Data System (ADS)

Djordjevich, Alexandar; Savović, Svetislav

2017-03-01

The state of mode coupling in 340 μm GeO2 doped core-silica clad optical fibers is investigated in this article using the power flow equation. The coupling coefficient in this equation was first tuned such that the equation could correctly reconstruct previously reported measured output power distributions. It was found that the GeO2 doped core-silica clad optical fiber showed stronger mode coupling than both, glass and popular plastic optical fibers. Consequently, the equilibrium as well as steady state mode distributions were achieved at shorter fiber lengths in GeO2 doped core-silica clad optical fibers.

Microtomographic quantification of hydraulic clay mineral displacement effects during a CO2 sequestration experiment with saline aquifer sandstone.

PubMed

Sell, Kathleen; Enzmann, Frieder; Kersten, Michael; Spangenberg, Erik

2013-01-02

We combined a noninvasive tomographic imaging technique with an invasive open-system core-flooding experiment and compared the results of the pre- and postflooded states of an experimental sandstone core sample from an ongoing field trial for carbon dioxide geosequestration. For the experiment, a rock core sample of 80 mL volume was taken from the 629 m Stuttgart Formation storage domain of a saline sandstone aquifer at the CCS research pilot plant Ketzin, Germany. Supercritical carbon dioxide and synthetical brine were injected under in situ reservoir p/T-conditions at an average flow rate of 0.1 mL/min for 256 h. X-ray computed microtomographic imaging was carried out before and after the core-flooding experiment at a spatial voxel resolution of 27 μm. No significant changes in microstructure were found at the tomographic imaging resolution including porosity and pore size distribution, except of an increase of depositional heterogeneous distribution of clay minerals in the pores. The digitized rock data were used as direct real microstructure input to the GeoDict software package, to simulate Navier-Stokes flow by a lattice Boltzmann equation solver. This procedure yielded 3D pressure and flow velocity fields, and revealed that the migration of clay particles decreased the permeability tensor probably due to clogging of pore openings.

Multiphysical simulation analysis of the dislocation structure in germanium single crystals

NASA Astrophysics Data System (ADS)

Podkopaev, O. I.; Artemyev, V. V.; Smirnov, A. D.; Mamedov, V. M.; Sid'ko, A. P.; Kalaev, V. V.; Kravtsova, E. D.; Shimanskii, A. F.

2016-09-01

To grow high-quality germanium crystals is one of the most important problems of growth industry. The dislocation density is an important parameter of the quality of single crystals. The dislocation densities in germanium crystals 100 mm in diameter, which have various shapes of the side surface and are grown by the Czochralski technique, are experimentally measured. The crystal growth is numerically simulated using heat-transfer and hydrodynamics models and the Alexander-Haasen dislocation model in terms of the CGSim software package. A comparison of the experimental and calculated dislocation densities shows that the dislocation model can be applied to study lattice defects in germanium crystals and to improve their quality.

Trace Gas Retrievals from the GeoTASO Aircraft Instrument During the DISCOVER-AQ Campaigns

NASA Astrophysics Data System (ADS)

Nowlan, C. R.; Liu, X.; Leitch, J. W.; Liu, C.; Gonzalez Abad, G.; Chance, K.; Delker, T.; Good, W. S.; Murcray, F.; Ruppert, L.; Kaptchen, P. F.; Loughner, C.; Follette-Cook, M. B.; Pickering, K. E.

2014-12-01

The Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) instrument is a recently-developed passive remote sensing instrument capable of making 2-D measurements of trace gases from aircraft. GeoTASO was developed under NASA's Instrument Incubator program and is a test-bed instrument for the Geostationary Coastal and Air Pollution Events (GEO-CAPE) decadal survey and the upcoming Tropospheric Emissions: Monitoring of Pollution (TEMPO) satellite missions. The instrument collects spectra of backscattered UV-visible radiation for the detection of tropospheric trace gases such as NO2, ozone, formaldehyde and SO2. GeoTASO flew on the NASA HU-25C Falcon aircraft during the 2013 (Texas) and 2014 (Colorado) DISCOVER-AQ field campaigns, making satellite-analog measurements of trace gases at a spatial resolution of approximately 500x500 m over urban areas, power plants and other industrial sources of pollution. We present the GeoTASO retrieval algorithms, trace gas measurement results, and validation comparisons with ground-based observations and other aircraft instruments during these campaigns.

A crystalline germanium flexible thin-film transistor

NASA Astrophysics Data System (ADS)

Higashi, H.; Nakano, M.; Kudo, K.; Fujita, Y.; Yamada, S.; Kanashima, T.; Tsunoda, I.; Nakashima, H.; Hamaya, K.

2017-11-01

We experimentally demonstrate a flexible thin-film transistor (TFT) with (111)-oriented crystalline germanium (Ge) layers grown by a gold-induced crystallization method. Accumulation-mode metal source/drain p-channel Ge TFTs are fabricated on a polyimide film at ≤ 400 ° C . A field-effect mobility (μFE) of 10.7 cm2/Vs is obtained, meaning the highest μFE in the p-TFTs fabricated at ≤ 400 ° C on flexible plastic substrates. This study will lead to high-performance flexible electronics based on an inorganic-semiconductor channel.

Analysis of the X-ray emission spectra of copper, germanium and rubidium plasmas produced at the Phelix laser facility

NASA Astrophysics Data System (ADS)

Comet, M.; Pain, J.-C.; Gilleron, F.; Piron, R.; Denis-Petit, D.; Méot, V.; Gosselin, G.; Morel, P.; Hannachi, F.; Gobet, F.; Tarisien, M.; Versteegen, M.

2017-03-01

We present the analysis of X-ray emission spectra of copper, germanium and rubidium plasmas measured at the Phelix laser facility. The laser intensity was around 6×1014 W.cm-2. The analysis is based on the hypothesis of an homogeneous plasma in local thermodynamic equilibrium using an effective temperature. This temperature is deduced from hydrodynamic simulations and collisional-radiative computations. Spectra are then calculated using the LTE opacity codes OPAMCDF and SCO-RCG and compared to experimental data.

Carbon Capture and Utilization in the Industrial Sector.

PubMed

Psarras, Peter C; Comello, Stephen; Bains, Praveen; Charoensawadpong, Panunya; Reichelstein, Stefan; Wilcox, Jennifer

2017-10-03

The fabrication and manufacturing processes of industrial commodities such as iron, glass, and cement are carbon-intensive, accounting for 23% of global CO 2 emissions. As a climate mitigation strategy, CO 2 capture from flue gases of industrial processes-much like that of the power sector-has not experienced wide adoption given its high associated costs. However, some industrial processes with relatively high CO 2 flue concentration may be viable candidates to cost-competitively supply CO 2 for utilization purposes (e.g., polymer manufacturing, etc.). This work develops a methodology that determines the levelized cost ($/tCO 2 ) of separating, compressing, and transporting carbon dioxide. A top-down model determines the cost of separating and compressing CO 2 across 18 industrial processes. Further, the study calculates the cost of transporting CO 2 via pipeline and tanker truck to appropriately paired sinks using a bottom-up cost model and geo-referencing approach. The results show that truck transportation is generally the low-cost alternative given the relatively small volumes (ca. 100 kt CO 2 /a). We apply our methodology to a regional case study in Pennsylvania, which shows steel and cement manufacturing paired to suitable sinks as having the lowest levelized cost of capture, compression, and transportation.

Filterability of the suspension from germanium precipitation with aqueous tannin extract solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mikhailov, N.F.; Petropol'skii, V.M.; Semenenko, L.E.

1978-01-01

We have already described the use of a neutral aqueous solution of tannin extract to recover germanium from collecting-mains liquor in coking plants. Further pilot commercial trials have encountered problems with the poor filterability of the precipitate obtained when germanium is extracted with this reagent in alkaline media. There are published references to the colloidal nature of the precipitated tannin-germanium complex. It is also known that the alkalinity of the medium influences the degree of association in colloidal systems to a marked extent. Accordingly, special research was needed to establish the relationship between the pH of the precipitation medium andmore » the filterability of the germanium deposit. Samples of collecting-mains liquor were taken from one of the southern coking plants to determine the optimum filtration behavior. The collecting-mains liquor should first be purged of volatile ammonia and then adjusted to pH = 6.5 to 6.7 for precipitation.« less

Enhanced light trapping by focused ion beam (FIB) induced self-organized nanoripples on germanium (100) surface

NASA Astrophysics Data System (ADS)

Kamaliya, Bhaveshkumar; Mote, Rakesh G.; Aslam, Mohammed; Fu, Jing

2018-03-01

In this paper, we demonstrate enhanced light trapping by self-organized nanoripples on the germanium surface. The enhanced light trapping leading to high absorption of light is confirmed by the experimental studies as well as the numerical simulations using the finite-difference time-domain method. We used gallium ion (Ga+) focused ion beam to enable the formation of the self-organized nanoripples on the germanium (100) surface. During the fabrication, the overlap of the scanning beam is varied from zero to negative value and found to influence the orientation of the nanoripples. Evolution of nanostructures with the variation of beam overlap is investigated. Parallel, perpendicular, and randomly aligned nanoripples with respect to the scanning direction are obtained via manipulation of the scanning beam overlap. 95% broadband absorptance is measured in the visible electromagnetic region for the nanorippled germanium surface. The reported light absorption enhancement can significantly improve the efficiency of germanium-silicon based photovoltaic systems.

Silicon and germanium nanowire electronics: physics of conventional and unconventional transistors

NASA Astrophysics Data System (ADS)

Weber, Walter M.; Mikolajick, Thomas

2017-06-01

Research in the field of electronics of 1D group-IV semiconductor structures has attracted increasing attention over the past 15 years. The exceptional combination of the unique 1D electronic transport properties with the mature material know-how of highly integrated silicon and germanium technology holds the promise of enhancing state-of-the-art electronics. In addition of providing conduction channels that can bring conventional field effect transistors to the uttermost scaling limits, the physics of 1D group IV nanowires endows new device principles. Such unconventional silicon and germanium nanowire devices are contenders for beyond complementary metal oxide semiconductor (CMOS) computing by virtue of their distinct switching behavior and higher expressive value. This review conveys to the reader a systematic recapitulation and analysis of the physics of silicon and germanium nanowires and the most relevant CMOS and CMOS-like devices built from silicon and germanium nanowires, including inversion mode, junctionless, steep-slope, quantum well and reconfigurable transistors.

Bioavailable concentrations of germanium and rare earth elements in soil as affected by low molecular weight organic acids and root exudates

NASA Astrophysics Data System (ADS)

Wiche, Oliver; Székely, Balázs; Kummer, Nicolai-Alexeji; Heinemann, Ute; Tesch, Silke; Heilmeier, Hermann

2014-05-01

Availability of elements in soil to plant is generally dependent on the solubility and mobility of elements in soil solution which is controlled by soil, elemental properties and plant-soil interactions. Low molecular organic acids or other root exudates may increase mobility and availability of certain elements for plants as an effect of lowering pH in the rhizosphere and complexation. However, these processes take place in a larger volume in soil, therefore to understand their nature, it is also important to know in which layers of the soil what factors modify these processes. In this work the influence of citric acid and root exudates of white lupin (Lupinus albus L.) on bioavailable concentrations of germanium, lanthan, neodymium, gadolinium and erbium in soil solution and uptake in root and shoot of rape (Brassica napus L.), comfrey (Symphytum officinale L.), common millet (Panicum milliaceum L.) and oat (Avena sativa L.) was investigated. Two different pot experiments were conducted: (1) the mentioned plant species were treated with nutrient solutions containing various amount of citric acid; (2) white lupin was cultivated in mixed culture (0 % lupin, 33 % lupin) with oat (Avena sativa L.) and soil solution was obtained by plastic suction cups placed at various depths. As a result, addition of citric acid significantly increased germanium concentrations in plant tissue of comfrey and rape and increased translocation of germanium, lanthan, neodymium, gadolinium and erbium from root to shoot. The cultivation of white lupin in mixed culture with oat led to significantly higher concentrations of germanium and increasing concentrations of lanthan, neodymium, gadolinium and erbium in soil solution and aboveground plant tissue. In these pots concentrations of citric acid in soil solution were significantly higher than in the control. The results show, that low molecular organic acids exuded by plant roots are of great importance for the mobilization of germanium, lanthan, neodymium, gadolinium and erbium in the rhizosphere and therefore the enhancement of bioavailability of the mentioned elements to plants. Based on the suction cup experiment we conclude that in vertical soil profile the bioavailable germanium is heavily affected by the activity of exudates, as the complexation processes of germanium take place at the root zone and below affected by the interplay of the infiltration of citric acid solutions and the actually produced exudates. These studies have been carried out in the framework of the PhytoGerm project, financed by the Federal Ministry of Education and Research, Germany. BS contributed as an Alexander von Humboldt Research Fellow. The authors are grateful to students and laboratory assistants contributing in the field work and sample preparation.

Study on spectroscopic properties and effects of tungsten ions in 2Bi2O3-3GeO2/SiO2 glasses.

PubMed

Yu, Pingsheng; Su, Liangbi; Cheng, Junhua; Zhang, Xia; Xu, Jun

2017-04-01

The 2Bi 2 O 3 -3GeO 2 /SiO 2 glass samples have been prepared by the conventional melt quenching technique. XRD patterns, absorption spectra, excitation-emission spectra and Raman measurements were utilized to characterize the synthesized glasses. When substitute SiO 2 for GeO 2 , the 0.4Bi 2 O 3 -(0.4-0.1)GeO 2 -(0.2-0.5)SiO 2 glasses exhibit strong emission centered at about 475nm (under 300nm excitation), and the decay constants are within the scope of 20-40ns. W doping into 2Bi 2 O 3 -3SiO 2 glass could increase the emission intensity of 470nm, and the W-doped 2Bi 2 O 3 -3SiO 2 glass has shown another emission at about 433nm with much shorter decay time (near 10ns). The 2Bi 2 O 3 -3GeO 2 /SiO 2 glass system could be the possible candidate for scintillator in high energy physics applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Documentation and Validation of the Goddard Earth Observing System (GEOS) Data Assimilation System, Version 4

NASA Technical Reports Server (NTRS)

Suarez, Max J. (Editor); daSilva, Arlindo; Dee, Dick; Bloom, Stephen; Bosilovich, Michael; Pawson, Steven; Schubert, Siegfried; Wu, Man-Li; Sienkiewicz, Meta; Stajner, Ivanka

2005-01-01

This document describes the structure and validation of a frozen version of the Goddard Earth Observing System Data Assimilation System (GEOS DAS): GEOS-4.0.3. Significant features of GEOS-4 include: version 3 of the Community Climate Model (CCM3) with the addition of a finite volume dynamical core; version two of the Community Land Model (CLM2); the Physical-space Statistical Analysis System (PSAS); and an interactive retrieval system (iRET) for assimilating TOVS radiance data. Upon completion of the GEOS-4 validation in December 2003, GEOS-4 became operational on 15 January 2004. Products from GEOS-4 have been used in supporting field campaigns and for reprocessing several years of data for CERES.

Germanium Resistance Thermometer For Subkelvin Temperatures

NASA Technical Reports Server (NTRS)

Castles, Stephen H.

1993-01-01

Improved germanium resistance thermometer measures temperatures as small as 0.01 K accurately. Design provides large area for electrical connections (to reduce electrical gradients and increase sensitivity to changes in temperatures) and large heat sink (to minimize resistance heating). Gold pads on top and bottom of germanium crystal distribute electrical current and flow of heat nearly uniformly across crystal. Less expensive than magnetic thermometers or superconducting quantum interference devices (SQUID's) otherwise used.

Fermi level de-pinning of aluminium contacts to n-type germanium using thin atomic layer deposited layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gajula, D. R., E-mail: dgajula01@qub.ac.uk; Baine, P.; Armstrong, B. M.

Fermi-level pinning of aluminium on n-type germanium (n-Ge) was reduced by insertion of a thin interfacial dielectric by atomic layer deposition. The barrier height for aluminium contacts on n-Ge was reduced from 0.7 eV to a value of 0.28 eV for a thin Al{sub 2}O{sub 3} interfacial layer (∼2.8 nm). For diodes with an Al{sub 2}O{sub 3} interfacial layer, the contact resistance started to increase for layer thicknesses above 2.8 nm. For diodes with a HfO{sub 2} interfacial layer, the barrier height was also reduced but the contact resistance increased dramatically for layer thicknesses above 1.5 nm.

A sea cucumber-like BiOBr nanosheet/Zn2GeO4 nanorod heterostructure for enhanced visible light driven photocatalytic activity

NASA Astrophysics Data System (ADS)

Zhang, Zhiping; Ge, Xin; Zhang, Xueyu; Duan, Lianfeng; Li, Xuesong; Yang, Yue; Lü, Wei

2018-01-01

In present work, a two-step hydrothermal/solvothermal method was developed to fabricate sea cucumber-like p-n heterojunctions of p-BiOBr/n-Zn2GeO4. The BiOBr nanosheets were grafted onto the surface of Zn2GeO4 nanorods. BiOBr/Zn2GeO4 nanocomposites exhibit remarkable photocatalytic activity under visible-light irradiation, and photocatalytic activity was studied in the catalytic test of rhodamine B decolorization. The mechanism for improved photocatalytic activity is interpreted in terms of the formation of type II band alignment between BiOBr and Zn2GeO4, which is confirmed by UV-vis diffuse absorption and VB-XPS spectra. BiOBr nanosheet as an admirable electron transport medium provide desirable specific surface area for the nanocomposite and a suitable band gap for heterojunction structure. Furthermore, scavenger experiments confirmed that h+ and {{{{O}}}2}\\cdot - were the main oxygen active species in the decolorization process.

Surface Pressure Dependencies in the GEOS-Chem-Adjoint System and the Impact of the GEOS-5 Surface Pressure on CO2 Model Forecast

NASA Technical Reports Server (NTRS)

Lee, Meemong; Weidner, Richard

2016-01-01

In the GEOS-Chem Adjoint (GCA) system, the total (wet) surface pressure of the GEOS meteorology is employed as dry surface pressure, ignoring the presence of water vapor. The Jet Propulsion Laboratory (JPL) Carbon Monitoring System (CMS) research team has been evaluating the impact of the above discrepancy on the CO2 model forecast and the CO2 flux inversion. The JPL CMS research utilizes a multi-mission assimilation framework developed by the Multi-Mission Observation Operator (M2O2) research team at JPL extending the GCA system. The GCA-M2O2 framework facilitates mission-generic 3D and 4D-variational assimilations streamlining the interfaces to the satellite data products and prior emission inventories. The GCA-M2O2 framework currently integrates the GCA system version 35h and provides a dry surface pressure setup to allow the CO2 model forecast to be performed with the GEOS-5 surface pressure directly or after converting it to dry surface pressure.

Surface Pressure Dependencies in the Geos-Chem-Adjoint System and the Impact of the GEOS-5 Surface Pressure on CO2 Model Forecast

NASA Technical Reports Server (NTRS)

Lee, Meemong; Weidner, Richard

2016-01-01

In the GEOS-Chem Adjoint (GCA) system, the total (wet) surface pressure of the GEOS meteorology is employed as dry surface pressure, ignoring the presence of water vapor. The Jet Propulsion Laboratory (JPL) Carbon Monitoring System (CMS) research team has been evaluating the impact of the above discrepancy on the CO2 model forecast and the CO2 flux inversion. The JPL CMS research utilizes a multi-mission assimilation framework developed by the Multi-Mission Observation Operator (M2O2) research team at JPL extending the GCA system. The GCA-M2O2 framework facilitates mission-generic 3D and 4D-variational assimilations streamlining the interfaces to the satellite data products and prior emission inventories. The GCA-M2O2 framework currently integrates the GCA system version 35h and provides a dry surface pressure setup to allow the CO2 model forecast to be performed with the GEOS-5 surface pressure directly or after converting it to dry surface pressure.

Development of a new type of germanium detector for dark matter searches

NASA Astrophysics Data System (ADS)

Wei, Wenzhao

Monte Carlo simulation is an important tool used to develop a better understanding of important physical processes. This thesis describes three Monte Carlo simulations used to understand germanium detector response to low energy nuclear recoils and radiogenic backgrounds for direct dark matter searches. The first simulation is the verification of Barker-Mei model, a theoretical model for calculating the ionization efficiency for germanium detector for the energy range of 1 - 100 keV. Utilizing the shape analysis, a bin-to-bin comparison between simulation and experimental data was performed for verifying the accuracy of the Barker-Mei model. A percentage difference within 4% was achieved between data and simulation, which showed the validity of the Barker-Mei model. The second simulation is the study of a new type of germanium detector for n/gamma discrimination at 77 K with plasma time difference in pulse shape. Due to the poor time resolution, conventional P-type Point Contact (PPC) and coaxial germanium detectors are not capable of discriminating nuclear recoils from electron recoils. In this thesis, a new idea of using great detector granularity and plasma time difference in pulse shape to discriminate nuclear recoils from electron recoils with planar germanium detectors in strings was discussed. The anticipated sensitivity of this new detector array is shown for detecting dark matter. The last simulation is a study of a new type of germanium-detector array serving as a PMT screening facility for ultra-low background dark matter experiments using noble liquid xenon as detector material such LUX/LZ and XENON100/XENON1T. A well-shaped germanium detector array and a PMT were simulated to study the detector response to the signal and background for a better understanding of the radiogenic gamma rays from PMTs. The detector efficiency and other detector performance were presented in this work.

NCBI GEO: archive for functional genomics data sets--update.

PubMed

Barrett, Tanya; Wilhite, Stephen E; Ledoux, Pierre; Evangelista, Carlos; Kim, Irene F; Tomashevsky, Maxim; Marshall, Kimberly A; Phillippy, Katherine H; Sherman, Patti M; Holko, Michelle; Yefanov, Andrey; Lee, Hyeseung; Zhang, Naigong; Robertson, Cynthia L; Serova, Nadezhda; Davis, Sean; Soboleva, Alexandra

2013-01-01

The Gene Expression Omnibus (GEO, http://www.ncbi.nlm.nih.gov/geo/) is an international public repository for high-throughput microarray and next-generation sequence functional genomic data sets submitted by the research community. The resource supports archiving of raw data, processed data and metadata which are indexed, cross-linked and searchable. All data are freely available for download in a variety of formats. GEO also provides several web-based tools and strategies to assist users to query, analyse and visualize data. This article reports current status and recent database developments, including the release of GEO2R, an R-based web application that helps users analyse GEO data.

Novel high-efficiency visible-light responsive Ag 4(GeO 4) photocatalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Xianglin; Wang, Peng; Li, Mengmeng

A novel high-efficiency visible-light responsive Ag 4(GeO 4) photocatalyst was prepared by a facile hydrothermal method. The photocatalytic activity of as-prepared Ag 4(GeO 4) was evaluated by photodegradation of methylene blue (MB) dye and water splitting experiments. The photodegradation efficiency and oxygen production efficiency of Ag 4(GeO 4) were detected to be 2.9 and 1.9 times higher than those of Ag 2O. UVvis diffuse reflectance spectroscopy (DRS), photoluminescence experiment and photoelectric effect experiments prove that the good light response and high carrier separation efficiency facilitated by the internal electric field are the main reasons for Ag 4(GeO 4)'s excellent catalyticmore » activity. Radical-trapping experiments reveal that the photogenerated holes are the main active species. Lastly, first-principles theoretical calculations provide more insight into understanding the photocatalytic mechanism of the Ag 4(GeO 4) catalyst.« less

Novel high-efficiency visible-light responsive Ag 4(GeO 4) photocatalyst

DOE PAGES

Zhu, Xianglin; Wang, Peng; Li, Mengmeng; ...

2017-04-25

A novel high-efficiency visible-light responsive Ag 4(GeO 4) photocatalyst was prepared by a facile hydrothermal method. The photocatalytic activity of as-prepared Ag 4(GeO 4) was evaluated by photodegradation of methylene blue (MB) dye and water splitting experiments. The photodegradation efficiency and oxygen production efficiency of Ag 4(GeO 4) were detected to be 2.9 and 1.9 times higher than those of Ag 2O. UVvis diffuse reflectance spectroscopy (DRS), photoluminescence experiment and photoelectric effect experiments prove that the good light response and high carrier separation efficiency facilitated by the internal electric field are the main reasons for Ag 4(GeO 4)'s excellent catalyticmore » activity. Radical-trapping experiments reveal that the photogenerated holes are the main active species. Lastly, first-principles theoretical calculations provide more insight into understanding the photocatalytic mechanism of the Ag 4(GeO 4) catalyst.« less

Synthesis of ternary oxide for efficient photo catalytic conversion of CO2

NASA Astrophysics Data System (ADS)

Wan, Lijuan

2018-01-01

Zn2GeO4 Nan rods were prepared by solution phase route. The morphology and structure of the as-prepared products were characterized by scanning electron microscopy (SEM) and Bruner-Emmett-Teller (BET) surface area measurements. The results revealed that Zn2GeO4 Nan rods with higher surface area have higher photo catalytic activity in photo reduction of CO2 than Zn2GeO4 prepared through solid-state reaction.

Controlled synthesis of germanium nanoparticles by nonthermal plasmas

NASA Astrophysics Data System (ADS)

Ahadi, Amir Mohammad; Hunter, Katharine I.; Kramer, Nicolaas J.; Strunskus, Thomas; Kersten, Holger; Faupel, Franz; Kortshagen, Uwe R.

2016-02-01

The size, composition, and crystallinity of plasma produced nanoparticles are crucial factors for their physical and chemical properties. Here, we investigate the role of the process gas composition, particularly the hydrogen (H2) flow rate, on germanium (Ge) nanoparticles synthesized from a chlorinated precursor by nonthermal plasma. We demonstrate that the gas composition can significantly change the nanoparticle size and also adjust the surface chemistry by altering the dominant reaction mechanisms. A red shift of the Ge-Clx infrared absorptions with increasing H2 flow indicates a weakening of the Ge-Clx bonds at high H2 content. Furthermore, by changing the gas composition, the nanoparticles microstructure can be controlled from mostly amorphous at high hydrogen flow to diamond cubic crystalline at low hydrogen flow.

Comparing mass balance and adjoint methods for inverse modeling of nitrogen dioxide columns for global nitrogen oxide emissions

NASA Astrophysics Data System (ADS)

Cooper, Matthew; Martin, Randall V.; Padmanabhan, Akhila; Henze, Daven K.

2017-04-01

Satellite observations offer information applicable to top-down constraints on emission inventories through inverse modeling. Here we compare two methods of inverse modeling for emissions of nitrogen oxides (NOx) from nitrogen dioxide (NO2) columns using the GEOS-Chem chemical transport model and its adjoint. We treat the adjoint-based 4D-Var modeling approach for estimating top-down emissions as a benchmark against which to evaluate variations on the mass balance method. We use synthetic NO2 columns generated from known NOx emissions to serve as "truth." We find that error in mass balance inversions can be reduced by up to a factor of 2 with an iterative process that uses finite difference calculations of the local sensitivity of NO2 columns to a change in emissions. In a simplified experiment to recover local emission perturbations, horizontal smearing effects due to NOx transport are better resolved by the adjoint approach than by mass balance. For more complex emission changes, or at finer resolution, the iterative finite difference mass balance and adjoint methods produce similar global top-down inventories when inverting hourly synthetic observations, both reducing the a priori error by factors of 3-4. Inversions of simulated satellite observations from low Earth and geostationary orbits also indicate that both the mass balance and adjoint inversions produce similar results, reducing a priori error by a factor of 3. As the iterative finite difference mass balance method provides similar accuracy as the adjoint method, it offers the prospect of accurately estimating top-down NOx emissions using models that do not have an adjoint.

Ginger Essential Oil Ameliorates Hepatic Injury and Lipid Accumulation in High Fat Diet-Induced Nonalcoholic Fatty Liver Disease.

PubMed

Lai, Yi-Syuan; Lee, Wan-Ching; Lin, Yu-En; Ho, Chi-Tang; Lu, Kuan-Hung; Lin, Shih-Hang; Panyod, Suraphan; Chu, Yung-Lin; Sheen, Lee-Yan

2016-03-16

The objective of this study was to investigate the hepatoprotective efficacy and mechanism of action of ginger essential oil (GEO) against the development of nonalcoholic fatty liver disease (NAFLD). Mice were maintained on either a control diet or high-fat diet (HFD) supplemented with GEO (12.5, 62.5, and 125 mg/kg) or citral (2.5 and 25 mg/kg) for 12 weeks. We demonstrated that GEO and its major component (citral) lowered HFD-induced obesity in a dose-dependent manner, accompanied by anti-hyperlipidemic effects by reducing serum free fatty acid, triglyceride, and total cholesterol levels. Moreover, liver histological results showed that administration of 62.5 and 125 mg/kg GEO and 25 mg/kg citral significantly reduced hepatic lipid accumulation. Further assessment by Western blotting and investigation of the lipid metabolism revealed that hepatic protein expression of sterol regulatory element-binding protein-1c (SREBP-1c), acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), and cytochrome P450 2E1 (CYP2E1) were down-regulated by GEO and citral, indicating that GEO and citral suppressed HFD-stimulated lipid biosynthesis and oxidative stress. Furthermore, GEO and citral effectively enhanced the antioxidant capacities and reduced inflammatory response in mouse liver, which exerted protective effects against steatohepatitis. Collectively, GEO and citral exhibited potent hepatoprotective effects against NAFLD induced by HFD in obese mice. Thus, GEO might be an effective dietary supplement to ameliorate NAFLD-related metabolic diseases, and citral could play a vital role in its management.

Extrinsic germanium Blocked Impurity Bank (BIB) detectors

NASA Technical Reports Server (NTRS)

Krabach, Timothy N.; Huffman, James E.; Watson, Dan M.

1989-01-01

Ge:Ga blocked-impurity-band (BIB) detectors with long wavelength thresholds greater than 190 microns and peak quantum efficiencies of 4 percent, at an operating temperature of 1.8 K, have been fabricated. These proof of concept devices consist of a high purity germanium blocking layer epitaxially grown on a Ga-doped Ge substrate. This demonstration of BIB behavior in germanium enables the development of far infrared detector arrays similar to the current silicon-based devices. Present efforts are focussed on improving the chemical vapor deposition process used to create the blocking layer and on the lithographic processing required to produce monolithic detector arrays in germanium. Approaches to test the impurity levels in both the blocking and active layers are considered.

Electrodeposition at room temperature of amorphous silicon and germanium nanowires in ionic liquid

NASA Astrophysics Data System (ADS)

Martineau, F.; Namur, K.; Mallet, J.; Delavoie, F.; Endres, F.; Troyon, M.; Molinari, M.

2009-11-01

The electrodeposition at room temperature of silicon and germanium nanowires from the air- and water-stable ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P1,4) containing SiCl4 as Si source or GeCl4 as Ge source is investigated by cyclic voltammetry. By using nanoporous polycarbonate membranes as templates, it is possible to reproducibly grow pure silicon and germanium nanowires of different diameters. The nanowires are composed of pure amorphous silicon or germanium. The nanowires have homogeneous cylindrical shape with a roughness of a few nanometres on the wire surfaces. The nanowires' diameters and lengths well match with the initial membrane characteristics. Preliminary photoluminescence experiments exhibit strong emission in the near infrared for the amorphous silicon nanowires.

Liquid-liquid phase transition and anomalous diffusion in simulated liquid GeO 2

NASA Astrophysics Data System (ADS)

Hoang, Vo Van; Anh, Nguyen Huynh Tuan; Zung, Hoang

2007-03-01

We perform molecular dynamics (MD) simulation of diffusion in liquid GeO 2 at the temperatures ranged from 3000 to 5000 K and densities ranged from 3.65 to 7.90 g/cm 3. Simulations were done in a model containing 3000 particles with the new interatomic potentials for liquid and amorphous GeO 2, which have weak Coulomb interaction and Morse-type short-range interaction. We found a liquid-liquid phase transition in simulated liquid GeO 2 from a tetrahedral to an octahedral network structure upon compression. Moreover, such phase transition accompanied with an anomalous diffusion of particles in liquid GeO 2 that the diffusion constant of both Ge and O particles strongly increases with increasing density (e.g. with increasing pressure) and it shows a maximum at the density around 4.95 g/cm 3. The possible relation between anomalous diffusion of particles and structural phase transition in the system has been discussed.

Identification of Nanocrystalline Inclusions in Bismuth-Doped Silica Fibers and Preforms.

PubMed

Iskhakova, Liudmila D; Milovich, Filipp O; Mashinsky, Valery M; Zlenko, Alexander S; Borisovsky, Sergey E; Dianov, Evgeny M

2016-10-01

The nature of nanocrystalline inclusions and dopant distribution in bismuth-doped silicate fibers and preforms are studied by scanning and transmission electron microscopy, and energy and wavelength-dispersive X-ray microanalysis. The core compositions are Bi:SiO2, Bi:Al2O3-SiO2, Bi:GeO2-SiO2, Bi:Al2O3-GeO2-SiO2, and Bi:P2O5-Al2O3-GeO2-SiO2. Nanocrystals of metallic Bi, Bi2O3, SiO2, GeO2, and Bi4(GeO4)3 are observed in these glasses. These inclusions can be the reason for the background optical loss in bismuth-doped optical fibers. The bismuth concentration of 0.0048±0.0006 at% is directly measured in aluminosilicate optical fibers with effective laser generation (slope efficiency of 27% at room temperature).

Assessing Uncertainties in Gridded Emissions: A Case Study for Fossil Fuel Carbon Dioxide (FFCO2) Emission Data

NASA Technical Reports Server (NTRS)

Oda, T.; Ott, L.; Lauvaux, T.; Feng, S.; Bun, R.; Roman, M.; Baker, D. F.; Pawson, S.

2017-01-01

Fossil fuel carbon dioxide (CO2) emissions (FFCO2) are the largest input to the global carbon cycle on a decadal time scale. Because total emissions are assumed to be reasonably well constrained by fuel statistics, FFCO2 often serves as a reference in order to deduce carbon uptake by poorly understood terrestrial and ocean sinks. Conventional atmospheric CO2 flux inversions solve for spatially explicit regional sources and sinks and estimate land and ocean fluxes by subtracting FFCO2. Thus, errors in FFCO2 can propagate into the final inferred flux estimates. Gridded emissions are often based on disaggregation of emissions estimated at national or regional level. Although national and regional total FFCO2 are well known, gridded emission fields are subject to additional uncertainties due to the emission disaggregation. Assessing such uncertainties is often challenging because of the lack of physical measurements for evaluation. We first review difficulties in assessing uncertainties associated with gridded FFCO2 emission data and present several approaches for evaluation of such uncertainties at multiple scales. Given known limitations, inter-emission data differences are often used as a proxy for the uncertainty. The popular approach allows us to characterize differences in emissions, but does not allow us to fully quantify emission disaggregation biases. Our work aims to vicariously evaluate FFCO2 emission data using atmospheric models and measurements. We show a global simulation experiment where uncertainty estimates are propagated as an atmospheric tracer (uncertainty tracer) alongside CO2 in NASA's GEOS model and discuss implications of FFCO2 uncertainties in the context of flux inversions. We also demonstrate the use of high resolution urban CO2 simulations as a tool for objectively evaluating FFCO2 data over intense emission regions. Though this study focuses on FFCO2 emission data, the outcome of this study could also help improve the knowledge of similar gridded emissions data for non-CO2 compounds with similar emission characteristics.

Assessing uncertainties in gridded emissions: A case study for fossil fuel carbon dioxide (FFCO2) emission data

NASA Astrophysics Data System (ADS)

Oda, T.; Ott, L. E.; Lauvaux, T.; Feng, S.; Bun, R.; Roman, M. O.; Baker, D. F.; Pawson, S.

2017-12-01

Fossil fuel carbon dioxide (CO2) emissions (FFCO2) are the largest input to the global carbon cycle on a decadal time scale. Because total emissions are assumed to be reasonably well constrained by fuel statistics, FFCO2 often serves as a reference in order to deduce carbon uptake by poorly understood terrestrial and ocean sinks. Conventional atmospheric CO2 flux inversions solve for spatially explicit regional sources and sinks and estimate land and ocean fluxes by subtracting FFCO2. Thus, errors in FFCO2 can propagate into the final inferred flux estimates. Gridded emissions are often based on disaggregation of emissions estimated at national or regional level. Although national and regional total FFCO2 are well known, gridded emission fields are subject to additional uncertainties due to the emission disaggregation. Assessing such uncertainties is often challenging because of the lack of physical measurements for evaluation. We first review difficulties in assessing uncertainties associated with gridded FFCO2 emission data and present several approaches for evaluation of such uncertainties at multiple scales. Given known limitations, inter-emission data differences are often used as a proxy for the uncertainty. The popular approach allows us to characterize differences in emissions, but does not allow us to fully quantify emission disaggregation biases. Our work aims to vicariously evaluate FFCO2 emission data using atmospheric models and measurements. We show a global simulation experiment where uncertainty estimates are propagated as an atmospheric tracer (uncertainty tracer) alongside CO2 in NASA's GEOS model and discuss implications of FFCO2 uncertainties in the context of flux inversions. We also demonstrate the use of high resolution urban CO2 simulations as a tool for objectively evaluating FFCO2 data over intense emission regions. Though this study focuses on FFCO2 emission data, the outcome of this study could also help improve the knowledge of similar gridded emissions data for non-CO2 compounds that share emission sectors.

Quantum ballistic transport in strained epitaxial germanium

NASA Astrophysics Data System (ADS)

Gul, Y.; Holmes, S. N.; Newton, P. J.; Ellis, D. J. P.; Morrison, C.; Pepper, M.; Barnes, C. H. W.; Myronov, M.

2017-12-01

Large scale fabrication using Complementary Metal Oxide Semiconductor compatible technology of semiconductor nanostructures that operate on the principles of quantum transport is an exciting possibility now due to the recent development of ultra-high mobility hole gases in epitaxial germanium grown on standard silicon substrates. We present here a ballistic transport study of patterned surface gates on strained Ge quantum wells with SiGe barriers, which confirms the quantum characteristics of the Ge heavy hole valence band structure in 1-dimension. Quantised conductance at multiples of 2e2/h is a universal feature of hole transport in Ge up to 10 × (2e2/h). The behaviour of ballistic plateaus with finite source-drain bias and applied magnetic field is elucidated. In addition, a reordering of the ground state is observed.

Combined Recipe for Clinical Target Volume and Planning Target Volume Margins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stroom, Joep, E-mail: joep.stroom@fundacaochampalimaud.pt; Gilhuijs, Kenneth; Vieira, Sandra

2014-03-01

Purpose: To develop a combined recipe for clinical target volume (CTV) and planning target volume (PTV) margins. Methods and Materials: A widely accepted PTV margin recipe is M{sub geo} = aΣ{sub geo} + bσ{sub geo}, with Σ{sub geo} and σ{sub geo} standard deviations (SDs) representing systematic and random geometric uncertainties, respectively. On the basis of histopathology data of breast and lung tumors, we suggest describing the distribution of microscopic islets around the gross tumor volume (GTV) by a half-Gaussian with SD Σ{sub micro}, yielding as possible CTV margin recipe: M{sub micro} = ƒ(N{sub i}) × Σ{sub micro}, with N{sub i}more » the average number of microscopic islets per patient. To determine ƒ(N{sub i}), a computer model was developed that simulated radiation therapy of a spherical GTV with isotropic distribution of microscopic disease in a large group of virtual patients. The minimal margin that yielded D{sub min} <95% in maximally 10% of patients was calculated for various Σ{sub micro} and N{sub i}. Because Σ{sub micro} is independent of Σ{sub geo}, we propose they should be added quadratically, yielding for a combined GTV-to-PTV margin recipe: M{sub GTV-PTV} = √([aΣ{sub geo}]{sup 2} + [ƒ(N{sub i})Σ{sub micro}]{sup 2}) + bσ{sub geo}. This was validated by the computer model through numerous simultaneous simulations of microscopic and geometric uncertainties. Results: The margin factor ƒ(N{sub i}) in a relevant range of Σ{sub micro} and N{sub i} can be given by: ƒ(N{sub i}) = 1.4 + 0.8log(N{sub i}). Filling in the other factors found in our simulations (a = 2.1 and b = 0.8) yields for the combined recipe: M{sub GTV-PTV} = √((2.1Σ{sub geo}){sup 2} + ([1.4 + 0.8log(N{sub i})] × Σ{sub micro}){sup 2}) + 0.8σ{sub geo}. The average margin difference between the simultaneous simulations and the above recipe was 0.2 ± 0.8 mm (1 SD). Calculating M{sub geo} and M{sub micro} separately and adding them linearly overestimated PTVs by on average 5 mm. Margin recipes based on tumor control probability (TCP) instead of D{sub min} criteria yielded similar results. Conclusions: A general recipe for GTV-to-PTV margins is proposed, which shows that CTV and PTV margins should be added in quadrature instead of linearly.« less

POD experiments using real and simulated time-sharing observations for GEO satellites in C-band transfer ranging system

NASA Astrophysics Data System (ADS)

Fen, Cao; XuHai, Yang; ZhiGang, Li; ChuGang, Feng

2016-08-01

The normal consecutive observing model in Chinese Area Positioning System (CAPS) can only supply observations of one GEO satellite in 1 day from one station. However, this can't satisfy the project need for observing many GEO satellites in 1 day. In order to obtain observations of several GEO satellites in 1 day like GPS/GLONASS/Galileo/BeiDou, the time-sharing observing model for GEO satellites in CAPS needs research. The principle of time-sharing observing model is illuminated with subsequent Precise Orbit Determination (POD) experiments using simulated time-sharing observations in 2005 and the real time-sharing observations in 2015. From time-sharing simulation experiments before 2014, the time-sharing observing 6 GEO satellites every 2 h has nearly the same orbit precision with the consecutive observing model. From POD experiments using the real time-sharing observations, POD precision for ZX12# and Yatai7# are about 3.234 m and 2.570 m, respectively, which indicates the time-sharing observing model is appropriate for CBTR system and can realize observing many GEO satellites in 1 day.

The GEOS-5 Data Assimilation System-Documentation of Versions 5.0.1, 5.1.0, and 5.2.0

NASA Technical Reports Server (NTRS)

Suarez, Max J.; Rienecker, M. M.; Todling, R.; Bacmeister, J.; Takacs, L.; Liu, H. C.; Gu, W.; Sienkiewicz, M.; Koster, R. D.; Gelaro, R.;

Assessment of policy impacts on carbon capture and sequestration and bioenergy for U.S.' coal and natural gas power plants

NASA Astrophysics Data System (ADS)

Spokas, K.; Patrizio, P.; Leduc, S.; Mesfun, S.; Kraxner, F.

2017-12-01

Reducing electricity-sector emissions relies heavily on countries' abilities to either transition away from carbon-intensive energy generation or to sequester its resultant emissions with carbon capture and storage (CCS) technologies. The use of biomass energy technologies in conjunction with carbon capture and sequestration (BECCS) presents the opportunity for net reductions in atmospheric carbon dioxide. In this study, we investigate the limitations of several common policy mechanisms to incentivize the deployment of BECCS using the techno-economic spatial optimization model BeWhere (www.iiasa.ac.at/bewhere). We consider a set of coal and natural gas power plants in the United States (U.S.) selected using a screening process that considers capacity, boiler age, and capacity factor for electricity-generation units from the EPA 2014 eGRID database. The set makes up 470 GW of generation, and produces 8,400 PJ and 2.07 GtCO2 annually. Co-firing up to 15% for coal power plants is considered, using woody-biomass residues sourced from certified and managed U.S. forests obtained from the G4M (www.iiasa.ac.at/g4m) and GeoWiki (www.geo-wiki.org) database. Geologic storage is considered with injectivity and geomechanical limitations to ensure safe storage. Costs are minimized under two policy mechanisms: a carbon tax and geologic carbon sequestration credits, such as the Q45 credits. Results show that the carbon tax scenario incentivizes co-firing at low to medium carbon taxes, but is replaced by CCS at higher tax values. Carbon taxes do not strongly incentivize BECCS, as negative emissions associated with sequestering carbon content are not accounted as revenue. On the other hand, carbon credit scenarios result in significant CCS deployment, but lack any incentive for co-firing.

Early Earth Science Activities in the Sanford Underground Science and Engineering Laboratory at Homestake

NASA Astrophysics Data System (ADS)

Wang, J. S.; Glaser, S. D.; Moore, J. R.; Hart, K.; King, G.; Regan, T.; Bang, S. S.; Sani, R. K.; Roggenthen, W. M.

2007-12-01

On July 10, 2007, the former Homestake Mine, Lead, South Dakota, was selected as the development site for the Deep Underground Science and Engineering Laboratory, to become the Sanford Underground Science and Engineering Laboratory at Homestake. Work on refurbishment and certification of the Ross Shaft began in August 2007 to effect pumping of water that had reached the 5000 level in late July. Completion of this work will allow a physics and geosciences laboratory to be constructed on the 4,850 ft level (1,478 m from the surface). Concurrent with reentry operations, several earth science research activities have been initiated. These early activities are as follows: (1) Seismic monitoring system: Accelerometers will be installed in surface boreholes and underground drifts as they become available as a result of the reentry work. (2) Evaluation of the 300 level (91 m), which has multiple locations for horizontal access, is ongoing. This near- surface level, with varying overburden thicknesses, offers excellent opportunities to investigate the "critical zone" in terms of hydrology, ecology, and geochemistry, yielding measurements of both moisture and carbon fluxes to evaluate fluid exchanges with the atmosphere. (3) Water and soil samples were collected in the Ross Shaft as part of the first reentry work. Molecular survey of microbial diversity showed the presence of mesophilic and thermophilic cellulose-degrading microorganisms. (4) Supercritical carbon dioxide injection experiments are being planned that will take advantage of three pairs of existing, nearly vertical, open 8-inch (0.2 m) boreholes that are easily accessible from the Ross Shaft. The candidate holes are located between the 1550 and the 2900 levels and are between 90 to 180 m in length (5) Monitoring of the response of the water during the dewatering operations will be facilitated by the use of existing boreholes. Ultimately, the dewatering operation provide access to the 8000 level (depth of 2,438 m), the deepest level. These five examples of ongoing research activities should provide a basis for many other earth science and engineering investigations at this multilevel facility, which already has extensive underground workings. These examples address different aspects of three main themes identified as important by deep underground research communities: restless earth for geo-science, ground truth for geo-engineering, and dark life for geo-microbiology.

Low-temperature irradiation-induced defects in germanium: In situ analysis

NASA Astrophysics Data System (ADS)

Mesli, A.; Dobaczewski, L.; Nielsen, K. Bonde; Kolkovsky, Vl.; Petersen, M. Christian; Larsen, A. Nylandsted

2008-10-01

The electronic properties of defects resulting from electron irradiation of germanium at low temperatures have been investigated. The recent success in preparing n+p junctions on germanium has opened a new opportunity to address fundamental questions regarding point defects and their related energy levels by allowing an access to the lower half of the band gap. In this work we apply various space-charge capacitance-transient spectroscopy techniques connected on line with the electron-beam facility. In n -type germanium we identify a level at about 0.14 eV below the conduction band whose properties resemble in many respects those of a defect assigned previously to the close vacancy-interstitial or Frenkel pair. This pair seems to annihilate over a small barrier at about 70 K, and its stability is particularly sensitive to the irradiation temperature and energy. We also observe two coupled levels at 0.08 and 0.24 eV below the conduction band stable up to 160 K. Recent independent theoretical work has predicted the existence of the single and double donor of the germanium interstitial with energy levels matching exactly these two values. Given these identifications hold, they mark a major difference with silicon where both the Frenkel pair and self-interstitial have never been caught. In p -type germanium, two levels were found. The shallower one, located at about 0.14 eV above the valence band, is tentatively assigned to the vacancy. It exhibits a field-driven instability at about 80 K making its analysis quite difficult. The application of a reverse bias, required by the space-charge spectroscopy, leads to a strong drift process sweeping this defect out of the observation area without necessarily provoking its annealing. Unlike silicon, in which the vacancy has four charge states, only one vacancy-related level seems to exist in germanium and this level is very likely a double acceptor. Finally, a very peculiar observation is made on a hole midgap trap, which, in many respects, behaves as the boron interstitial in silicon. This has led us to suggest that it may stem from the gallium interstitial, a natural dopant of our germanium materials, whose presence would be the fingerprint of the Watkins replacement mechanism in germanium.

The performance of the Muon Veto of the G erda experiment

NASA Astrophysics Data System (ADS)

Freund, K.; Falkenstein, R.; Grabmayr, P.; Hegai, A.; Jochum, J.; Knapp, M.; Lubsandorzhiev, B.; Ritter, F.; Schmitt, C.; Schütz, A.-K.; Jitnikov, I.; Shevchik, E.; Shirchenko, M.; Zinatulina, D.

2016-05-01

Low background experiments need a suppression of cosmogenically induced events. The Gerda experiment located at Lngs is searching for the 0ν β β decay of ^{76}Ge. It is equipped with an active muon veto the main part of which is a water Cherenkov veto with 66 PMTs in the water tank surrounding the Gerda cryostat. With this system 806 live days have been recorded, 491 days were combined muon-germanium data. A muon detection efficiency of \\varepsilon _\\upmu d=(99.935± 0.015) % was found in a Monte Carlo simulation for the muons depositing energy in the germanium detectors. By examining coincident muon-germanium events a rejection efficiency of \\varepsilon _{\\upmu r}=(99.2_{-0.4}^{+0.3}) % was found. Without veto condition the muons by themselves would cause a background index of {BI}_{μ }=(3.16 ± 0.85)× 10^{-3} cts/(keV\\cdot kg\\cdot year) at Q_{β β }.

Passivation of micro-strip gas chambers with an interstitial germanium coating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyamoto, J.; Knoll, G.F.; Amos, N.

1996-12-31

Micro-strip gas chambers (MSGCs) were constructed in the Solid-State Electronics Laboratory of the University of Michigan and their performance was studied. Many efforts have been made in the past to construct MSGCs that yield high absolute gas gain and stable gas gain. Introducing a thin germanium layer has been effective for passivation but difficulties associated with the poor adhesiveness of the thin layer have been a serious obstacle. This paper reports on a new method used to overcome these difficulties. Unlike the conventional coating method the thin germanium layer was successfully deposited between the strip lines. This technique requires amore » careful geometric alignment of a second photomask with the original micro-strip structure. The resulting detector performance was noteworthy and an absolute gas gain of 2 {center_dot} 10{sup 4} was easily achieved by the new chamber. The chamber`s gain instability was also reduced significantly compared with those without interstitial coating.« less

Multi-keV x-ray sources from metal-lined cylindrical hohlraums

NASA Astrophysics Data System (ADS)

Jacquet, L.; Girard, F.; Primout, M.; Villette, B.; Stemmler, Ph.

2012-08-01

As multi-keV x-ray sources, plastic hohlraums with inner walls coated with titanium, copper, and germanium have been fired on Omega in September 2009. For all the targets, the measured and calculated multi-keV x-ray power time histories are in a good qualitative agreement. In the same irradiation conditions, measured multi-keV x-ray conversion rates are ˜6%-8% for titanium, ˜2% for copper, and ˜0.5% for germanium. For titanium and copper hohlraums, the measured conversion rates are about two times higher than those given by hydroradiative computations. Conversely, for the germanium hohlraum, a rather good agreement is found between measured and computed conversion rates. To explain these findings, multi-keV integrated emissivities calculated with RADIOM [M. Busquet, Phys. Fluids 85, 4191 (1993)], the nonlocal-thermal-equilibrium atomic physics model used in our computations, have been compared to emissivities obtained from different other models. These comparisons provide an attractive way to explain the discrepancies between experimental and calculated quantitative results.

Graded Index Silicon Geranium on Lattice Matched Silicon Geranium Semiconductor Alloy

NASA Technical Reports Server (NTRS)

Park, Yeonjoon (Inventor); Choi, Sang H. (Inventor); King, Glen C. (Inventor); Elliott, James R., Jr. (Inventor); Stoakley, Diane M. (Inventor)

2009-01-01

A lattice matched silicon germanium (SiGe) semiconductive alloy is formed when a {111} crystal plane of a cubic diamond structure SiGe is grown on the {0001} C-plane of a single crystalline Al2O3 substrate such that a <110> orientation of the cubic diamond structure SiGe is aligned with a <1,0,-1,0> orientation of the {0001} C-plane. A lattice match between the substrate and the SiGe is achieved by using a SiGe composition that is 0.7223 atomic percent silicon and 0.2777 atomic percent germanium. A layer of Si(1-x), ,Ge(x) is formed on the cubic diamond structure SiGe. The value of X (i) defines an atomic percent of germanium satisfying 0.2277

Wilcoxon signed-rank-based technique for the pulse-shape analysis of HPGe detectors

NASA Astrophysics Data System (ADS)

Martín, S.; Quintana, B.; Barrientos, D.

2016-07-01

The characterization of the electric response of segmented-contact high-purity germanium detectors requires scanning systems capable of accurately associating each pulse with the position of the interaction that generated it. This process requires an algorithm sensitive to changes above the electronic noise in the pulse shapes produced at different positions, depending on the resolution of the Ge crystal. In this work, a pulse-shape comparison technique based on the Wilcoxon signed-rank test has been developed. It provides a method to distinguish pulses coming from different interaction points in the germanium crystal. Therefore, this technique is a necessary step for building a reliable pulse-shape database that can be used later for the determination of the position of interaction for γ-ray tracking spectrometry devices such as AGATA, GRETA or GERDA. The method was validated by comparison with a χ2 test using simulated and experimental pulses corresponding to a Broad Energy germanium detector (BEGe).

Intrinsic germanium detector used in borehole sonde for uranium exploration

USGS Publications Warehouse

Senftle, F.E.; Moxham, R.M.; Tanner, A.B.; Boynton, G.R.; Philbin, P.W.; Baicker, J.A.

1976-01-01

A borehole sonde (~1.7 m long; 7.3 cm diameter) using a 200 mm2 planar intrinsic germanium detector, mounted in a cryostat cooled by removable canisters of frozen propane, has been constructed and tested. The sonde is especially useful in measuring X- and low-energy gamma-ray spectra (40–400 keV). Laboratory tests in an artificial borehole facility indicate its potential for in-situ uranium analyses in boreholes irrespective of the state of equilibrium in the uranium series. Both natural gamma-ray and neutron-activation gamma-ray spectra have been measured with the sonde. Although the neutron-activation technique yields greater sensitivity, improvements being made in the resolution and efficiency of intrinsic germanium detectors suggest that it will soon be possible to use a similar sonde in the passive mode for measurement of uranium in a borehole down to about 0.1% with acceptable accuracy. Using a similar detector and neutron activation, the sonde can be used to measure uranium down to 0.01%.

NCBI GEO: archive for functional genomics data sets—update

PubMed Central

Barrett, Tanya; Wilhite, Stephen E.; Ledoux, Pierre; Evangelista, Carlos; Kim, Irene F.; Tomashevsky, Maxim; Marshall, Kimberly A.; Phillippy, Katherine H.; Sherman, Patti M.; Holko, Michelle; Yefanov, Andrey; Lee, Hyeseung; Zhang, Naigong; Robertson, Cynthia L.; Serova, Nadezhda; Davis, Sean; Soboleva, Alexandra

2013-01-01

The Gene Expression Omnibus (GEO, http://www.ncbi.nlm.nih.gov/geo/) is an international public repository for high-throughput microarray and next-generation sequence functional genomic data sets submitted by the research community. The resource supports archiving of raw data, processed data and metadata which are indexed, cross-linked and searchable. All data are freely available for download in a variety of formats. GEO also provides several web-based tools and strategies to assist users to query, analyse and visualize data. This article reports current status and recent database developments, including the release of GEO2R, an R-based web application that helps users analyse GEO data. PMID:23193258

Small- Geo Solar Array: New Generation Of Solar Arrays For Commercial Telecom Satellites For Power Ranges Between 2,5 KW And 7,5 KW

NASA Astrophysics Data System (ADS)

Paarmann, Carola; Muller, Jens; Mende, Thomas; Borner, Carsten; Mascher, Rolf

2011-10-01

In the frame of the ESA supported Artes 11 program a new generation of GEO telecommunication satellites is under development. This platform will cover the power range from 2 to 5 kW. ASTRIUM GmbH is contracted to develop and design the Solar Array for this platform. Furthermore the manufacturing and the qualification of a PFM wing for the first flight model is foreseen. The satellite platform, called Small-GEO, is developed under the responsibility of OHB System. This first Small-GEO satellite is designated to be delivered to HISPASAT for operation. The concept of ASTRIUM GmbH is to use all the experiences from the very successful EUROSTAR 2000+, EUROSTAR-3000 and the ALPHABUS platform and to adapt the technologies to the Small- GEO Solar Array. With the benefit of the huge in-orbit heritage of these programs, the remaining risks for the Small-GEO Solar Array can be minimized. The development of the Small-GEO Solar Array extends the ASTRIUM GmbH product portfolio by covering now the complete power range between 2 kW and 31 kW. This paper provides an overview of the different configurations, their main design features and parameters.

MSM-Metal Semiconductor Metal Photo-detector Using Black Silicon Germanium (SiGe) for Extended Wavelength Near Infrared Detection

DTIC Science & Technology

2012-09-01

MSM) photodectors fabricated using black silicon-germanium on silicon substrate (Si1–xGex//Si) for I-V, optical response, external quantum ...material for Si for many applications in low-power and high-speed semiconductor device technologies (4, 5). It is a promising material for quantum well ...MSM-Metal Semiconductor Metal Photo-detector Using Black Silicon Germanium (SiGe) for Extended Wavelength Near Infrared Detection by Fred

Hydrothermal germanium over the southern East pacific rise.

PubMed

Mortlock, R A; Froelich, P N

1986-01-03

Germanium enrichment in the oceanic water column above the southern axis of the East Pacific Rise results from hydrothermal solutions emanating from hot springs along the rise crest. This plume signature provides a new oceanic tracer of reactions between seawater and sea floor basalts during hydrothermal alteration. In contrast to the sharp plumes of (3)He and manganese, the germanium plume is broad and diffuse, suggesting the existence of pervasive venting of low-temperature solutions off the ridge axis.

Near-infrared emission from mesoporous crystalline germanium

NASA Astrophysics Data System (ADS)

Boucherif, Abderraouf; Korinek, Andreas; Aimez, Vincent; Arès, Richard

2014-10-01

Mesoporous crystalline germanium was fabricated by bipolar electrochemical etching of Ge wafer in HF-based electrolyte. It yields uniform mesoporous germanium layers composed of high density of crystallites with an average size 5-7 nm. Subsequent extended chemical etching allows tuning of crystallites size while preserving the same chemical composition. This highly controllable nanostructure exhibits photoluminescence emission above the bulk Ge bandgap, in the near-infrared range (1095-1360nm) with strong evidence of quantum confinement within the crystallites.

The germination of germanium

NASA Astrophysics Data System (ADS)

Burdette, Shawn C.; Thornton, Brett F.

2018-02-01

Shawn C. Burdette and Brett F. Thornton explore how germanium developed from a missing element in Mendeleev's periodic table to an enabler for the information age, while retaining a nomenclature oddity.

Crystal Orientation Effect on the Subsurface Deformation of Monocrystalline Germanium in Nanometric Cutting.

PubMed

Lai, Min; Zhang, Xiaodong; Fang, Fengzhou

2017-12-01

Molecular dynamics simulations of nanometric cutting on monocrystalline germanium are conducted to investigate the subsurface deformation during and after nanometric cutting. The continuous random network model of amorphous germanium is established by molecular dynamics simulation, and its characteristic parameters are extracted to compare with those of the machined deformed layer. The coordination number distribution and radial distribution function (RDF) show that the machined surface presents the similar amorphous state. The anisotropic subsurface deformation is studied by nanometric cutting on the (010), (101), and (111) crystal planes of germanium, respectively. The deformed structures are prone to extend along the 110 slip system, which leads to the difference in the shape and thickness of the deformed layer on various directions and crystal planes. On machined surface, the greater thickness of subsurface deformed layer induces the greater surface recovery height. In order to get the critical thickness limit of deformed layer on machined surface of germanium, the optimized cutting direction on each crystal plane is suggested according to the relevance of the nanometric cutting to the nanoindentation.

Geometrical and band-structure effects on phonon-limited hole mobility in rectangular cross-sectional germanium nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, H., E-mail: tanaka@semicon.kuee.kyoto-u.ac.jp; Mori, S.; Morioka, N.

2014-12-21

We calculated the phonon-limited hole mobility in rectangular cross-sectional [001], [110], [111], and [112]-oriented germanium nanowires, and the hole transport characteristics were investigated. A tight-binding approximation was used for holes, and phonons were described by a valence force field model. Then, scattering probability of holes by phonons was calculated taking account of hole-phonon interaction atomistically, and the linearized Boltzmann's transport equation was solved to calculate the hole mobility at low longitudinal field. The dependence of the hole mobility on nanowire geometry was analyzed in terms of the valence band structure of germanium nanowires, and it was found that the dependencemore » was qualitatively reproduced by considering an average effective mass and the density of states of holes. The calculation revealed that [110] germanium nanowires with large height along the [001] direction show high hole mobility. Germanium nanowires with this geometry are also expected to exhibit high electron mobility in our previous work, and thus they are promising for complementary metal-oxide-semiconductor (CMOS) applications.« less

Enabling Energy Efficiency and Polarity Control in Germanium Nanowire Transistors by Individually Gated Nanojunctions.

PubMed

Trommer, Jens; Heinzig, André; Mühle, Uwe; Löffler, Markus; Winzer, Annett; Jordan, Paul M; Beister, Jürgen; Baldauf, Tim; Geidel, Marion; Adolphi, Barbara; Zschech, Ehrenfried; Mikolajick, Thomas; Weber, Walter M

2017-02-28

Germanium is a promising material for future very large scale integration transistors, due to its superior hole mobility. However, germanium-based devices typically suffer from high reverse junction leakage due to the low band-gap energy of 0.66 eV and therefore are characterized by high static power dissipation. In this paper, we experimentally demonstrate a solution to suppress the off-state leakage in germanium nanowire Schottky barrier transistors. Thereto, a device layout with two independent gates is used to induce an additional energy barrier to the channel that blocks the undesired carrier type. In addition, the polarity of the same doping-free device can be dynamically switched between p- and n-type. The shown germanium nanowire approach is able to outperform previous polarity-controllable device concepts on other material systems in terms of threshold voltages and normalized on-currents. The dielectric and Schottky barrier interface properties of the device are analyzed in detail. Finite-element drift-diffusion simulations reveal that both leakage current suppression and polarity control can also be achieved at highly scaled geometries, providing solutions for future energy-efficient systems.

Fabrication of Ta2O5/GeNx gate insulator stack for Ge metal-insulator-semiconductor structures by electron-cyclotron-resonance plasma nitridation and sputtering deposition techniques

NASA Astrophysics Data System (ADS)

Otani, Yohei; Itayama, Yasuhiro; Tanaka, Takuo; Fukuda, Yukio; Toyota, Hiroshi; Ono, Toshiro; Mitsui, Minoru; Nakagawa, Kiyokazu

2007-04-01

The authors have fabricated germanium (Ge) metal-insulator-semiconductor (MIS) structures with a 7-nm-thick tantalum pentaoxide (Ta2O5)/2-nm-thick germanium nitride (GeNx) gate insulator stack by electron-cyclotron-resonance plasma nitridation and sputtering deposition. They found that pure GeNx ultrathin layers can be formed by the direct plasma nitridation of the Ge surface without substrate heating. X-ray photoelectron spectroscopy revealed no oxidation of the GeNx layer after the Ta2O5 sputtering deposition. The fabricated MIS capacitor with a capacitance equivalent thickness of 4.3nm showed excellent leakage current characteristics. The interface trap density obtained by the modified conductance method was 4×1011cm-2eV-1 at the midgap.

The isotope composition of inorganic germanium in seawater and deep sea sponges

NASA Astrophysics Data System (ADS)

Guillermic, Maxence; Lalonde, Stefan V.; Hendry, Katharine R.; Rouxel, Olivier J.

2017-09-01

Although dissolved concentrations of germanium (Ge) and silicon (Si) in modern seawater are tightly correlated, uncertainties still exist in the modern marine Ge cycle. Germanium stable isotope systematics in marine systems should provide additional constraints on marine Ge sources and sinks, however the low concentration of Ge in seawater presents an analytical challenge for isotopic measurement. Here, we present a new method of pre-concentration of inorganic Ge from seawater which was applied to measure three Ge isotope profiles in the Southern Ocean and deep seawater from the Atlantic and Pacific Oceans. Germanium isotopic measurements were performed on Ge amounts as low as 2.6 ng using a double-spike approach and a hydride generation system coupled to a MC-ICP-MS. Germanium was co-precipitated with iron hydroxide and then purified through anion-exchange chromatography. Results for the deep (i.e. >1000 m depth) Pacific Ocean off Hawaii (nearby Loihi Seamount) and the deep Atlantic off Bermuda (BATS station) showed nearly identical δ74/70Ge values at 3.19 ± 0.31‰ (2SD, n = 9) and 2.93 ± 0.10‰ (2SD, n = 2), respectively. Vertical distributions of Ge concentration and isotope composition in the deep Southern Ocean for water depth > 1300 m yielded an average δ74/70Ge = 3.13 ± 0.25‰ (2SD, n = 14) and Ge/Si = 0.80 ± 0.09 μmol/mol (2SD, n = 12). Significant variations in δ74/70Ge, from 2.62 to 3.71‰, were measured in the first 1000 m in one station of the Southern Ocean near Sars Seamount in the Drake Passage, with the heaviest values measured in surface waters. Isotope fractionation by diatoms during opal biomineralization may explain the enrichment in heavy isotopes for both Ge and Si in surface seawater. However, examination of both oceanographic parameters and δ74/70Ge values suggest also that water mass mixing and potential contribution of shelf-derived Ge also could contribute to the variations. Combining these results with new Ge isotope data for deep-sea sponges sampled nearby allowed us to determine a Ge isotope fractionation factor of -0.87 ± 0.37‰ (2SD, n = 12) during Ge uptake by sponges. Although Ge has long been considered as a geochemical twin of Si, this work underpins fundamental differences in their isotopic behaviors both during biomineralization processes and in their oceanic distributions. This suggests that combined with Si isotopes, Ge isotopes hold significant promise as a complementary proxy for delineating biological versus source effects in the evolution of the marine silicon cycle through time.

Thermodynamics of Alloys: Studies of Nickel-Gallium, Nickel-Germanium and Nickel-Rhodium Alloys.

DTIC Science & Technology

NICKEL ALLOYS, *GALLIUM ALLOYS, *GERMANIUM ALLOYS, * RHODIUM ALLOYS, *PHASE STUDIES, THERMODYNAMICS, INTERMETALLIC COMPOUNDS, FREE ENERGY, ENTROPY, HEAT OF FORMATION, CRYSTAL STRUCTURE, UNITED KINGDOM.

Atomic Scale Structure of (001) Hydrogen-Induced Platelets in Germanium

NASA Astrophysics Data System (ADS)

David, Marie-Laure; Pizzagalli, Laurent; Pailloux, Fréderic; Barbot, Jean François

2009-04-01

An accurate characterization of the structure of hydrogen-induced platelets is a prerequisite for investigating both hydrogen aggregation and formation of larger defects. On the basis of quantitative high resolution transmission electron microscopy experiments combined with extensive first principles calculations, we present a model for the atomic structure of (001) hydrogen-induced platelets in germanium. It involves broken Ge-Ge bonds in the [001] direction that are dihydride passivated, vacancies, and trapped H2 molecules, showing that the species involved in platelet formation depend on the habit plane. This model explains all previous experimental observations.

Germanium CMOS potential from material and process perspectives: Be more positive about germanium

NASA Astrophysics Data System (ADS)

Toriumi, Akira; Nishimura, Tomonori

2018-01-01

CMOS miniaturization is now approaching the sub-10 nm level, and further downscaling is expected. This size scaling will end sooner or later, however, because the typical size is approaching the atomic distance level in crystalline Si. In addition, it is said that electron transport in FETs is ballistic or nearly ballistic, which means that the injection velocity at the virtual source is a physical parameter relevant for estimating the driving current. Channel-materials with higher carrier mobility than Si are nonetheless needed, and the carrier mobility in the channels is a parameter important with regard to increasing the injection velocity. Although the density of states in the channel has not been discussed often, it too is relevant for estimating the channel current. Both the mobility and the density of states are in principle related to the effective mass of the carrier. From this device physics viewpoint, we expect germanium (Ge) CMOS to be promising for scaling beyond the Si CMOS limit because the bulk mobility values of electrons and holes in Ge are much higher than those of electrons and holes in Si, and the electron effective mass in Ge is not much less than that in III-V compounds. There is a debate that Ge should be used for p-MOSFETs and III-V compounds for n-MOSFETs, but considering that the variability or nonuniformity of the FET performance in today’s CMOS LSIs is a big challenge, it seems that much more attention should be paid to the simplicity of the material design and of the processing steps. Nevertheless, Ge faces a number of challenges even in case that only the FET level is concerned. One of the big problems with Ge CMOS technology has been its poor performance in n-MOSFETs. While the hole mobility in p-FETs has been improved, the electron mobility in the inversion layer of Ge FETs remains a serious concern. If this is due to the inherent properties of Ge, only p-MOSFETs might be used for device applications. To make Ge CMOS devices practically viable, we need to understand why electron mobility is severely degraded in the inversion layer in Ge n-channel MOSFETs and to find out how it can be increased. In the Si CMOS technology, the SiO2/Si interface has long been investigated and cannot be ignored even after the introduction of high-k gate stack technology. In that sense, the GeO2/Ge interface should be intensively studied to make the best of Ge’s advantages. Therefore we first discuss the GeO2/Ge interface with regard to its physical and electrical characteristics. When we regard Ge as a channel material beyond Si for high performance ULSIs, we also have to seriously consider the gate stack scalability and reliability. The source/drain engineering, as well as the gate stack formation, is another challenge in Ge MOSFET design. Both the higher metal/Ge contact resistance and the larger p/n junction leakage current may be the consequences of Ge’s intrinsic properties because they are derived from the strong Fermi-level pinning and the narrow energy band gap, respectively. Even if the carrier transport in the channel may be ideally ballistic, these properties should degrade FET properties. The narrower energy band gap of Ge is often addressed, but the higher dielectric constant of Ge is rarely discussed. This is also the case for most of the other high-mobility materials. The dielectric constant is directly and negatively related to short-channel effects, and we have not been able to provide a substantial solution to overcome this hardship. We have to keep this in mind for the short-channel FET operation. Although a number of problems remain to be solved, in this paper, we view the current status of Ge FET technology positively. A number of (but not all) Ge-related challenges have been overcome in the past 10 years, which seems to be a good time to summarize the status of Ge technology, particularly materials engineering aspects rather than device integration issues. Since we cannot cover all of the results published to date, we mainly discuss fundamental aspects based on our experimental results. Remaining challenges are also addressed but not comprehensively. Integration issues are not discussed in this review. Finally, new types of electron devices utilizing Ge’s advantages are briefly introduced on the basis of our experimental results.

Cosmogenic activation of germanium used for tonne-scale rare event search experiments

NASA Astrophysics Data System (ADS)

Wei, W.-Z.; Mei, D.-M.; Zhang, C.

2017-11-01

We report a comprehensive study of cosmogenic activation of germanium used for tonne-scale rare event search experiments. The germanium exposure to cosmic rays on the Earth's surface are simulated with and without a shielding container using Geant4 for a given cosmic muon, neutron, and proton energy spectrum. The production rates of various radioactive isotopes are obtained for different sources separately. We find that fast neutron induced interactions dominate the production rate of cosmogenic activation. Geant4-based simulation results are compared with the calculation of ACTIVIA and the available experimental data. A reasonable agreement between Geant4 simulations and several experimental data sets is presented. We predict that cosmogenic activation of germanium can set limits to the sensitivity of the next generation of tonne-scale experiments.

Characteristics of signals originating near the lithium-diffused N+ contact of high purity germanium p-type point contact detectors

DOE PAGES

Aguayo, E.; Amman, M.; Avignone, F. T.; ...

2012-11-09

A study of signals originating near the lithium-diffused n+ contact of p-type point contact (PPC) high purity germanium detectors (HPGe) is presented. The transition region between the active germanium and the fully dead layer of the n+ contact is examined. Energy depositions in this transition region are shown to result in partial charge collection. This provides a mechanism for events with a well defined energy to contribute to the continuum of the energy spectrum at lower energies. A novel technique to quantify the contribution from this source of background is introduced. Furthermore, experiments that operate germanium detectors with a verymore » low energy threshold may benefit from the methods presented herein.« less

Modeling of dislocation dynamics in germanium Czochralski growth

NASA Astrophysics Data System (ADS)

Artemyev, V. V.; Smirnov, A. D.; Kalaev, V. V.; Mamedov, V. M.; Sidko, A. P.; Podkopaev, O. I.; Kravtsova, E. D.; Shimansky, A. F.

2017-06-01

Obtaining very high-purity germanium crystals with low dislocation density is a practically difficult problem, which requires knowledge and experience in growth processes. Dislocation density is one of the most important parameters defining the quality of germanium crystal. In this paper, we have performed experimental study of dislocation density during 4-in. germanium crystal growth using the Czochralski method and comprehensive unsteady modeling of the same crystal growth processes, taking into account global heat transfer, melt flow and melt/crystal interface shape evolution. Thermal stresses in the crystal and their relaxation with generation of dislocations within the Alexander-Haasen model have been calculated simultaneously with crystallization dynamics. Comparison to experimental data showed reasonable agreement for the temperature, interface shape and dislocation density in the crystal between calculation and experiment.

Thermal, structural and optical properties of new TeO2sbnd Sb2O3sbnd GeO2 ternary glasses

NASA Astrophysics Data System (ADS)

Pereira, C.; Barbosa, J.; Cassanjes, F. C.; Gonçalves, R. R.; Ribeiro, S. J. L.; Poirier, G.

2016-12-01

In this work the novel glass system TeO2sbnd Sb2O3sbnd GeO2 was investigated and promising glass compositions were selected for further specific studies. Glass samples in the (80-0.8x)TeO2-(20-0.2x)Sb2O3-xGeO2 molar composition were prepared by the melt-quenching method with a glass-forming domain from x = 10 to x = 90. Samples were investigated by XRD, DSC, FTIR, Raman spectroscopy and UV-visible absorption. The XRD and DSC results bring informations about the non-crystalline state and thermal properties of these materials. It has been observed that higher GeO2 contents lead to higher glass transition temperatures and thermal stabilities against crystallization. FTIR and Raman spectroscopies suggest a progressive incorporation of GeO2 in the covalent network of TeO2 with conversion of structural units TeO4 to TeO3. Absorption spectra revealed the high visible transparency of these samples and an increase of the optical band gap with GeO2 addition, in agreement with a decreasing polarizability of the glass network. Er3+ doped and Er3+/Yb3+ codoped samples were also studied with respect to their infrared emission properties and higher GeO2 contents lead to an increase in IR emission intensity at 1,5 μm as well as longer radiative lifetimes. Finally, upconversion emission in the visible were also recorded and were shown to be strongly dependent of the composition.

Preparation of Ho3+/Tm3+ Co-doped Lanthanum Tungsten Germanium Tellurite Glass Fiber and Its Laser Performance for 2.0 μm.

PubMed

Zhou, Dechun; Bai, Xuemei; Zhou, Hang

2017-03-17

Ho 3+ /Tm 3+ co-doped 50TeO 2 -25GeO 2 -3WO 3 -5La 2 O 3 -3Nb 2 O 5 -5Li 2 O-9BaF 2 glass fiber is prepared with the rod-tube drawing method of 15 μm core diameter and 125 μm inner cladding diameter applied in the 2.0 μm-infrared laser. The 2.0 μm luminescence properties of the core glass are researched and the fluorescence intensity variation for different Tm 3+ doping concentration is systematically analyzed. The results show that the 2.0 μm luminescence of Ho 3+ is greatly influenced by the doping concentration ratio of Ho 3+ to Tm 3+ and that the maximum fluorescence intensity of the core glass can be obtained and its emission cross section can reach 0.933 × 10 -21  cm 2 when the sensitized proportion of holmium to thulium is 0.3 to 0.7 (mol%). Simultaneously, the maximum phonon energy of the core glass sample is 753 cm -1 , which is significantly lower than that of silicate, gallate and germanate glass and the smaller matrix phonon energy can be conductive to the increase 2.0 μm-band emission intensity. The continuous laser with the maximum laser output power of 0.993 W and 2051 nm -wavelength of 31.9%-slope efficiency is output within the 0.5 m glass fiber and the experiment adopts 1560 nm erbium-doped fiber laser(EDFL) as the pump source and the self-built all-fiber laser. Therefore, the glass fiber has excellent laser characteristics and it is suitable for the 2.0 μm-band laser.

Preparation of Ho3+/Tm3+ Co-doped Lanthanum Tungsten Germanium Tellurite Glass Fiber and Its Laser Performance for 2.0 μm

NASA Astrophysics Data System (ADS)

Zhou, Dechun; Bai, Xuemei; Zhou, Hang

2017-03-01

Ho3+/Tm3+ co-doped 50TeO2-25GeO2-3WO3-5La2O3-3Nb2O5-5Li2O-9BaF2 glass fiber is prepared with the rod-tube drawing method of 15 μm core diameter and 125 μm inner cladding diameter applied in the 2.0 μm-infrared laser. The 2.0 μm luminescence properties of the core glass are researched and the fluorescence intensity variation for different Tm3+ doping concentration is systematically analyzed. The results show that the 2.0 μm luminescence of Ho3+ is greatly influenced by the doping concentration ratio of Ho3+ to Tm3+ and that the maximum fluorescence intensity of the core glass can be obtained and its emission cross section can reach 0.933 × 10-21 cm2 when the sensitized proportion of holmium to thulium is 0.3 to 0.7 (mol%). Simultaneously, the maximum phonon energy of the core glass sample is 753 cm-1, which is significantly lower than that of silicate, gallate and germanate glass and the smaller matrix phonon energy can be conductive to the increase 2.0 μm-band emission intensity. The continuous laser with the maximum laser output power of 0.993 W and 2051 nm -wavelength of 31.9%-slope efficiency is output within the 0.5 m glass fiber and the experiment adopts 1560 nm erbium-doped fiber laser(EDFL) as the pump source and the self-built all-fiber laser. Therefore, the glass fiber has excellent laser characteristics and it is suitable for the 2.0 μm-band laser.

Preparation of Ho3+/Tm3+ Co-doped Lanthanum Tungsten Germanium Tellurite Glass Fiber and Its Laser Performance for 2.0 μm

PubMed Central

Zhou, Dechun; Bai, Xuemei; Zhou, Hang

2017-01-01

Ho3+/Tm3+ co-doped 50TeO2-25GeO2-3WO3-5La2O3-3Nb2O5-5Li2O-9BaF2 glass fiber is prepared with the rod-tube drawing method of 15 μm core diameter and 125 μm inner cladding diameter applied in the 2.0 μm-infrared laser. The 2.0 μm luminescence properties of the core glass are researched and the fluorescence intensity variation for different Tm3+ doping concentration is systematically analyzed. The results show that the 2.0 μm luminescence of Ho3+ is greatly influenced by the doping concentration ratio of Ho3+ to Tm3+ and that the maximum fluorescence intensity of the core glass can be obtained and its emission cross section can reach 0.933 × 10−21 cm2 when the sensitized proportion of holmium to thulium is 0.3 to 0.7 (mol%). Simultaneously, the maximum phonon energy of the core glass sample is 753 cm−1, which is significantly lower than that of silicate, gallate and germanate glass and the smaller matrix phonon energy can be conductive to the increase 2.0 μm-band emission intensity. The continuous laser with the maximum laser output power of 0.993 W and 2051 nm -wavelength of 31.9%-slope efficiency is output within the 0.5 m glass fiber and the experiment adopts 1560 nm erbium-doped fiber laser(EDFL) as the pump source and the self-built all-fiber laser. Therefore, the glass fiber has excellent laser characteristics and it is suitable for the 2.0 μm-band laser. PMID:28303946

GeoEn -Research on Geo-Energy

NASA Astrophysics Data System (ADS)

Liebscher, A.; Scheck-Wenderoth, M.; GeoEn Research Group

2012-04-01

Axel Liebscher1, Magdalena Scheck-Wenderoth1 and the GeoEn Research Group1, 2,3 1 Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany 2 University Potsdam, Germany 3 BTU Cottbus, Germany One of the pressing challenges for the 21st century is a secure, sustainable and economical energy supply at simultaneous mitigation of its climate impact. Besides a switch to renewable energy resources, the exploration and exploitation of new, unconventional energy resources will play a major role as will the further use of fossil fuels. With the switch to renewable energies the question of geological energy storage will become an important topic whereas further use of fossil fuels requires strategies like CCS to reduce its negative climate impacts. These different aspects of geo-energy make complementary or competitive demands on the subsurface and its use. It is therefore essential to treat the subsurface as a geo-resource of its own right. So far, geo-resource related research has often focused on specific resource systems, e.g. ore forming systems, hydrocarbon systems or geothermal systems, providing results largely applicable only to the restricted range of physicochemical properties of the respective geo-resource systems. However, with the increasing use of the subsurface as important geo-resource, the different geo-resource systems tend to overlap and interact and also become much more complex due to the additional use or presence of artificial and technical matter, as is the case in geological CO2 storage. On the other hand, the combined use of the subsurface for different purposes may also create synergetic effects. GeoEn is a joint research project explicitly addressing the fundamental questions related to the sustainable and holistic use of the geo-resource subsurface with a special focus on geo-energy. Project partners are the German Research Centre for Geosciences (GFZ), the University of Potsdam (UP) and the Brandenburg University of Technology (BTU). GeoEn research addresses CO2 capture, transport and utilization, CO2 storage, the unconventional energy resource shale gas and geothermal technologies. These four core topics are studied in an integrated approach using the synergy of cross-cutting themes. The latter encompass new exploration and reservoir technologies as well as innovative monitoring methods, both complemented by numerical simulations of the relevant processes including flow dynamics or heat transfer in the subsurface and along the technological process chains. Accordingly, synergies derived from the cross-cutting topics improve both methodological development applicable in equal measure to the utilization of geothermal energy and of shale gas as well as to the use and monitoring of CO2 storage. Complementary, new modelling approaches are developed that allow the simulation of involved processes to predict the occurrence and physical properties of potential reservoirs and the changes that may be induced by their utilization. We present first results with respect to exploration strategies, monitoring technologies and modeling approaches for the pilot storage site for CO2 in Ketzin and the geothermal research platform Groß-Schönebeck, where the respective technologies are tested and monitored.

An unexpected epoxidation of benzil derivatives in their reaction with a germene.

PubMed

El Kettani, Sakina Ech-Cherif; Lazraq, Mohamed; Ouhsaine, Fatima; Gornitzka, Heinz; Ranaivonjatovo, Henri; Escudié, Jean

2008-11-07

The germene Mes(2)Ge=CR(2) (Mes = 2,4,6-trimethylphenyl, CR(2) = fluorenylidene) reacts with various benzil derivatives to lead to germanium-containing bicyclic epoxides by an unexpected new type of epoxidation reaction.

Remote plasma enhanced chemical deposition of non-crystalline GeO2 on Ge and Si substrates.

PubMed

Lucovsky, Gerald; Zeller, Daniel

2011-09-01

Non-crystalline GeO2 films remote were plasma deposited at 300 degrees C onto Ge substrates after a final rinse in NH4OH. The reactant precursors gas were: (i) down-stream injected 2% GeH4 in He as the Ge precursor, and (ii) up-stream, plasma excited O2-He mixtures as the O precursor. Films annealed at 400 degrees C displayed no evidence for loss of O resulting in Ge sub-oxide formation, and for a 5-6 eV mid-gap absorption associated with formation of GeOx suboxide bonding, x < 2. These films were stable in normal laboratory ambients with no evidence for reaction with atmospheric water. Films deposited on Ge and annealed at 600 degrees C and 700 degrees C display spectra indicative of loss of O-atoms, accompanied with a 5.5 eV absorption. X-ray absorption spectroscopy and many-electron theory are combined to describe symmetries and degeneracies for O-vacancy bonding defects. These include comparisons with remote plasma-deposited non-crystalline SiO2 on Si substrates with SiON interfacial layers. Three different properties of remote plasma GeO2 films are addressed comparisons between (i) conduction band and band edge states of GeO2 and SiO2, and (ii) electronic structure of O-atom vacancy defects in GeO2 and SiO2, and differences between (iii) annealing of GeO2 films on Ge substrates, and Si substrates passivated with SiON interfacial transition regions important for device applications.

Molecular mechanisms of water table lowering and nitrogen deposition in affecting greenhouse gas emissions from a Tibetan alpine wetland.

PubMed

Wang, Hao; Yu, Lingfei; Zhang, Zhenhua; Liu, Wei; Chen, Litong; Cao, Guangmin; Yue, Haowei; Zhou, Jizhong; Yang, Yunfeng; Tang, Yanhong; He, Jin-Sheng

2017-02-01

Rapid climate change and intensified human activities have resulted in water table lowering (WTL) and enhanced nitrogen (N) deposition in Tibetan alpine wetlands. These changes may alter the magnitude and direction of greenhouse gas (GHG) emissions, affecting the climate impact of these fragile ecosystems. We conducted a mesocosm experiment combined with a metagenomics approach (GeoChip 5.0) to elucidate the effects of WTL (-20 cm relative to control) and N deposition (30 kg N ha -1  yr -1 ) on carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O) fluxes as well as the underlying mechanisms. Our results showed that WTL reduced CH 4 emissions by 57.4% averaged over three growing seasons compared with no-WTL plots, but had no significant effect on net CO 2 uptake or N 2 O flux. N deposition increased net CO 2 uptake by 25.2% in comparison with no-N deposition plots and turned the mesocosms from N 2 O sinks to N 2 O sources, but had little influence on CH 4 emissions. The interactions between WTL and N deposition were not detected in all GHG emissions. As a result, WTL and N deposition both reduced the global warming potential (GWP) of growing season GHG budgets on a 100-year time horizon, but via different mechanisms. WTL reduced GWP from 337.3 to -480.1 g CO 2 -eq m -2 mostly because of decreased CH 4 emissions, while N deposition reduced GWP from 21.0 to -163.8 g CO 2 -eq m -2 , mainly owing to increased net CO 2 uptake. GeoChip analysis revealed that decreased CH 4 production potential, rather than increased CH 4 oxidation potential, may lead to the reduction in net CH 4 emissions, and decreased nitrification potential and increased denitrification potential affected N 2 O fluxes under WTL conditions. Our study highlights the importance of microbial mechanisms in regulating ecosystem-scale GHG responses to environmental changes. © 2016 John Wiley & Sons Ltd.

Alternations of Structure and Functional Activity of Below Ground Microbial Communities at Elevated Atmospheric Carbon Dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Zhili; Xu, Meiying; Deng, Ye

2010-05-17

The global atmospheric concentration of CO2 has increased by more than 30percent since the industrial revolution. Although the stimulating effects of elevated CO2 (eCO2) on plant growth and primary productivity have been well studied, its influences on belowground microbial communities are poorly understood and controversial. In this study, we showed a significant change in the structure and functional potential of soil microbial communities at eCO2 in a grassland ecosystem, the BioCON (Biodiversity, CO2 and Nitrogen) experimental site (http://www.biocon.umn.edu/) using a comprehensive functional gene array, GeoChip 3.0, which contains about 28,0000 probes and covers approximately 57,000 gene variants from 292 functionalmore » gene families involved in carbon, nitrogen, phosphorus and sulfur cycles as well as other functional processes. GeoChip data indicated that the functional structure of microbial communities was markedly different between ambient CO2 (aCO2) and eCO2 by detrended correspondence analysis (DCA) of all 5001 detected functional gene probes although no significant differences were detected in the overall microbial diversity. A further analysis of 1503 detected functional genes involved in C, N, P, and S cycles showed that a considerable portion (39percent) of them were only detected under either aCO2 (14percent) or eCO2 (25percent), indicating that the functional characteristics of the microbial community were significantly altered by eCO2. Also, for those shared genes (61percent) detected, some significantly (p<0.05) changed their abundance at eCO2. Especially, genes involved in labile C degradation, such as amyA, egl, and ara for starch, cellulose, and hemicelluloses, respectively, C fixation (e.g., rbcL, pcc/acc), N fixation (nifH), and phosphorus utilization (ppx) were significantly increased under eCO2, while those involved in decomposing recalcitrant C, such as glx, lip, and mnp for lignin degradation remained unchanged. This study provides insights into our understanding of belowground microbial communities and their feedbacks to terrestrial ecosystems at eCO2.« less

Measurements of Unexpected Ozone Loss in a Nighttime Space Shuttle Exhaust Plume: Implications for Geo-Engineering Projects

NASA Astrophysics Data System (ADS)

Avallone, L. M.; Kalnajs, L. E.; Toohey, D. W.; Ross, M. N.

2008-12-01

Measurements of ozone, carbon dioxide and particulate water were made in the nighttime exhaust plume of the Space Shuttle (STS-116) on 9 December 2006 as part of the PUMA/WAVE campaign (Plume Ultrafast Measurements Acquisition/WB-57F Ascent Video Experiment). The launch took place from Kennedy Space Center at 8:47 pm (local time) on a moonless night and the WB-57F aircraft penetrated the shuttle plume approximately 25 minutes after launch in the lowermost stratosphere. Ozone loss is not predicted to occur in a nighttime Space Shuttle plume since it has long been assumed that the main ozone loss mechanism associated with rocket emissions requires solar photolysis to drive several chlorine-based catalytic cycles. However, the nighttime in situ observations show an unexpected loss of ozone of approximately 250 ppb in the evolving exhaust plume, inconsistent with model predictions. We will present the observations of the shuttle exhaust plume composition and the results of photochemical models of the Space Shuttle plume. We will show that models constrained by known rocket emission kinetics, including afterburning, and reasonable plume dispersion rates, based on the CO2 observations, cannot explain the observed ozone loss. We will propose potential explanations for the lack of agreement between models and the observations, and will discuss the implications of these explanations for our understanding of the composition of rocket emissions. We will describe the potential consequences of the observed ozone loss for long-term damage to the stratospheric ozone layer should geo-engineering projects based on rocket launches be employed.

Rapid growth in nitrogen dioxide pollution over Western China, 2005-2013

NASA Astrophysics Data System (ADS)

Cui, Y.-Z.; Lin, J.-T.; Song, C.; Liu, M.-Y.; Yan, Y.-Y.; Xu, Y.; Huang, B.

2015-12-01

Western China has experienced rapid industrialization and urbanization since the implementation of the National Western Development Strategies (the "Go West" movement) in 1999. This transition has affected the spatial and temporal characteristics of nitrogen dioxide (NO2) pollution. In this study, we analyze the trends and variability of tropospheric NO2 vertical column densities (VCDs) from 2005 to 2013 over Western China, based on a wavelet analysis on monthly mean NO2 data derived from the Ozone Monitoring Instrument (OMI) measurements. We focus on the anthropogenic NO2 by subtracting region-specific "background" values dominated by natural sources. We find significant NO2 growth over Western China between 2005 and 2013 (8.6 ± 0.9 % yr-1 on average, relative to 2005), with the largest increments (15 % yr-1 or more) over parts of several city clusters. The NO2 pollution in most provincial regions rose rapidly from 2005 to 2011 but stabilized or declined afterwards. The NO2 trends were driven mainly by changes in anthropogenic emissions, as confirmed by a nested GEOS-Chem model simulation and a comparison with Chinese official emission statistics. The rate of NO2 growth during 2005-2013 reaches 11.3 ± 1.0 % yr-1 over Northwestern China, exceeding the rates over Southwestern China (5.9 ± 0.6 % yr-1) and the three well-known polluted regions in the east (5.3 ± 0.8 % yr-1 over Beijing-Tianjin-Hebei, 4.0 ± 0.6 % yr-1} over the Yangtze River Delta, and -3.3 ± 0.3 % yr-1 over the Pearl River Delta). Additional socioeconomic analyses suggest that the rapid NO2 growth in Northwestern China is likely related to the fast developing resource- and pollution-intensive industries along with the "Go West" movement as well as relatively weak emission controls. Further efforts should be made to alleviate NOx pollution to achieve sustainable development in Western China.

Rapid growth in nitrogen dioxide pollution over Western China, 2005-2013

NASA Astrophysics Data System (ADS)

Cui, Yuanzheng; Lin, Jintai; Song, Chunqiao; Liu, Mengyao; Yan, Yingying; Xu, Yuan; Huang, Bo

2016-05-01

Western China has experienced rapid industrialization and urbanization since the implementation of the National Western Development Strategies (the "Go West" movement) in 1999. This transition has affected the spatial and temporal characteristics of nitrogen dioxide (NO2) pollution. In this study, we analyze the trends and variability of tropospheric NO2 vertical column densities (VCDs) from 2005 to 2013 over Western China, based on a wavelet analysis on monthly mean NO2 data derived from the Ozone Monitoring Instrument (OMI) measurements. We focus on the anthropogenic NO2 by subtracting region-specific "background" values dominated by natural sources. After removing the background influences, we find significant anthropogenic NO2 growth over Western China between 2005 and 2013 (8.6 ± 0.9 % yr-1 on average, relative to 2005), with the largest increments (15 % yr-1 or more) over parts of several city clusters. The NO2 pollution in most provincial-level regions rose rapidly from 2005 to 2011 but stabilized or declined afterwards. The NO2 trends were driven mainly by changes in anthropogenic emissions, as confirmed by a nested GEOS-Chem model simulation and a comparison with Chinese official emission statistics. The rate of NO2 growth during 2005-2013 reaches 11.3 ± 1.0 % yr-1 over Northwestern China, exceeding the rates over Southwestern China (5.9 ± 0.6 % yr-1) and the three well-known polluted regions in the east (5.3 ± 0.8 % yr-1 over Beijing-Tianjin-Hebei, 4.0 ± 0.6 % yr-1 over the Yangtze River Delta, and -3.3 ± 0.3 % yr-1 over the Pearl River Delta). Subsequent socioeconomic analyses suggest that the rapid NO2 growth over Northwestern China is likely related to the fast developing resource- and pollution-intensive industries along with the "Go West" movement as well as relatively weak emission controls. Further efforts should be made to alleviate NOx pollution to achieve sustainable development in Western China.

Space based inverse modeling of seasonal variations of anthropogenic and natural emissions of nitrogen oxides over China and effects of uncertainties in model meteorology and chemistry

NASA Astrophysics Data System (ADS)

Lin, J.

2011-12-01

Nitrogen oxides (NOx ≡ NO + NO2) are important atmospheric constituents affecting the tropospheric chemistry, surface air quality and climatic forcing. They are emitted both from anthropogenic and from natural (soil, lightning, biomass burning, etc.) sources, which can be estimated inversely from satellite remote sensing of the vertical column densities (VCDs) of nitrogen dioxide (NO2) in the troposphere. Based on VCDs of NO2 retrieved from OMI, a novel approach is developed in this study to separate anthropogenic emissions of NOx from natural sources over East China for 2006. It exploits the fact that anthropogenic and natural emissions vary with seasons with distinctive patterns. The global chemical transport model (CTM) GEOS-Chem is used to establish the relationship between VCDs of NO2 and emissions of NOx for individual sources. Derived soil emissions are compared to results from a newly developed bottom-up approach. Effects of uncertainties in model meteorology and chemistry over China, an important source of errors in the emission inversion, are evaluated systematically for the first time. Meteorological measurements from space and the ground are used to analyze errors in meteorological parameters driving the CTM.

The Hydrological Impact of Geoengineering in the Geoengineering Model Intercomparison Project (GeoMIP)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tilmes, S.; Fasullo, John; Lamarque, J.-F.

2013-10-14

Abstract: The hydrologic impact of enhancing Earth’s albedo due to solar radiation management (SRM) is investigated using simulations from 12 models contributing to the Geoengineering Model Intercomparison Project (GeoMIP). An artificial experiment is investigated, where global mean temperature is preserved at pre-industrial conditions, while atmospheric carbon dioxide concentrations are quadrupled. The associated reduction of downwelling surface solar radiation in a high CO2 environment leads to a reduction of global evaporation of 10% and 4% and precipitation of 6.1% and 6.3% over land and ocean, respectively. An initial reduction of latent heat flux at the surface is largely driven by reducedmore » evapotranspiration over land with instantly increasing CO2 concentrations in both experiments. A warming surface associated with the transient adjustment in the 4xCO2 experiment further generates an increase of global precipitation, with considerable regional changes, such as a significant precipitation reduction of 7% for the North American summer monsoon. Reduced global precipitation persists in the geoengineered experiment where temperatures are stabilized, with considerable regional rainfall deficits. Precipitation reductions that are consistent in sign across models are identified in the geoengineered experiment over monsoonal land regions of East Asia (6%), North America (7%), South America (6%) and South Africa (5%). In contrast to the 4xCO2 experiment, where the frequency of months with heavy precipitation intensity is increased by over 50%, it is reduced by up to 20% in the geoengineering scenario . The reduction in heavy precipitation is more pronounced over land than over the ocean, and accompanies a stronger reduction in evaporation over land. For northern mid-latitudes, maximum precipitation reduction over land ranges from 1 to 16% for individual models. For 45-65°N, the frequency of median to high intensity precipitation in summer is strongly reduced. These changes in precipitation in both total amount and frequency of extremes, point to a considerable weakening of the hydrological cycle in a geoengineered world.« less

Energy transport, polar amplification, and ITCZ shifts in the GeoMIP G1 ensemble

NASA Astrophysics Data System (ADS)

Russotto, Rick D.; Ackerman, Thomas P.

2018-02-01

The polar amplification of warming and the ability of the Intertropical Convergence Zone (ITCZ) to shift to the north or south are two very important problems in climate science. Examining these behaviors in global climate models (GCMs) running solar geoengineering experiments is helpful not only for predicting the effects of solar geoengineering but also for understanding how these processes work under increased carbon dioxide (CO2). Both polar amplification and ITCZ shifts are closely related to the meridional transport of moist static energy (MSE) by the atmosphere. This study examines changes in MSE transport in 10 fully coupled GCMs in experiment G1 of the Geoengineering Model Intercomparison Project (GeoMIP), in which the solar constant is reduced to compensate for the radiative forcing from abruptly quadrupled CO2 concentrations. In G1, poleward MSE transport decreases relative to preindustrial conditions in all models, in contrast to the Coupled Model Intercomparison Project phase 5 (CMIP5) abrupt4xCO2 experiment, in which poleward MSE transport increases. We show that since poleward energy transport decreases rather than increases, and local feedbacks cannot change the sign of an initial temperature change, the residual polar amplification in the G1 experiment must be due to the net positive forcing in the polar regions and net negative forcing in the tropics, which arise from the different spatial patterns of the simultaneously imposed solar and CO2 forcings. However, the reduction in poleward energy transport likely plays a role in limiting the polar warming in G1. An attribution study with a moist energy balance model shows that cloud feedbacks are the largest source of uncertainty regarding changes in poleward energy transport in midlatitudes in G1, as well as for changes in cross-equatorial energy transport, which are anticorrelated with ITCZ shifts.

Germanium: giving microelectronics an efficiency boost

USGS Publications Warehouse

Mercer, Celestine N.

2015-07-30

Germanium is an essentially nontoxic element, with the exception of only a few compounds. However, if dissolved concentrations in drinking water are as high as one or more parts per million chronic diseases may occur.

Determining orbital particle parameters of impacts into germanium using morphology analysis and calibration data from hypervelocity impact experiments in the laboratory

NASA Technical Reports Server (NTRS)

Paul, Klaus G.

1995-01-01

This paper describes the work that is done at the Lehrstuhl fur Raumfahrttechnik (lrt) at the Technische Universitat Munchen to examine particle impacts into germanium surfaces which were flown on board the LDEF satellite. Besides the description of the processing of the samples, a brief overview of the particle launchers at our institute is given together with descriptions of impact morphology of high- and hypervelocity particles into germanium. Since germanium is a brittle, almost glass-like material, the impact morphology may also be interesting for anyone dealing with materials such as optics and solar cells. The main focus of our investigations is to learn about the impacting particle's properties, for example mass, velocity and direction. This is done by examining the morphology, various geometry parameters, crater obliqueness and crater volume.

Alternating gradient photodetector

NASA Technical Reports Server (NTRS)

Overhauser, Albert W. (Inventor); Maserjian, Joseph (Inventor)

1989-01-01

A far infrared (FIR) range responsive photodetector is disclosed. There is a substrate of degenerate germanium. A plurality of alternating impurity-band and high resistivity layers of germanium are disposed on the substrate. The impurity-band layers have a doping concentration therein sufficiently high to include donor bands which can release electrons upon impingement by FIR photons of energy hv greater than an energy gap epsilon. The high resistivity layers have a doping concentration therein sufficiently low as to not include conducting donor bands and are depleted of electrons. Metal contacts are provided for applying an electrical field across the substrate and the plurality of layers. In the preferred embodiment as shown, the substrate is degenerate n-type (N++) germanium; the impurity-band layers are n+ layers of germanium doped to approximately the low 10(exp 16)/cu cm range; and, the high resistivity layers are n-layers of germanium doped to a maximum of approximately 10(exp)/cu cm. Additionally, the impurity-band layers have a thickness less than a conduction-electron diffusion length in germanium and likely to be in the range of 0.1 to 1.0 micron, the plurality of impurity-bands is of a number such that the flux of FIR photons passing therethrough will be substantially totally absorbed therein, the thickness of the high resistivity layers is such compared to the voltage applied that the voltage drop in each the high resistivity layers controls the occurence of impact ionization in the impurity-band layers to a desired level.

GEO Collisional Risk Assessment Based on Analysis of NASA-WISE Data and Modeling

DTIC Science & Technology

2015-10-18

GEO Collisional Risk Assessment Based on Analysis of NASA -WISE Data and Modeling Jeremy Murray Krezan1, Samantha Howard1, Phan D. Dao1, Derek...Surka2 1AFRL Space Vehicles Directorate,2Applied Technology Associates Incorporated From December 2009 through 2011 the NASA Wide-Field Infrared...of known debris. The NASA -WISE GEO belt debris population adds potentially thousands previously uncataloged objects. This paper describes

Measurement of Geo-neutrinos with KamLAND

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamada, Satoru

2011-11-23

Radioactive isotopes inside the Earth produce geo-neutrinos through beta decays. Geo-neutrinos could be direct probes to investigate the interior of the Earth as a supplement to the current geophysical survey that mainly relies on an indirect seismic approach. After the Kamioka liquid scintillator antineutrino detector (KamLAND) reported the first indication of geo-neutrinos in 2005, we have accumulated data for a total of 2,135 days of live-time and achieved a lower background level by purifying liquid scintillator. The number of obtained geo-neutrino events is 106{sub -28}{sup +29} corresponding to an electron antineutrino flux of 4.3{sub -1.1}{sup +1.2}x10{sup 6} cm{sup -2} s{supmore » -1} from {sup 238}U and {sup 232}Th series at the Earth's surface. The null hypothesis for the existence of geo-neutrinos is excluded at the 99.997% confidence level. We combined this precise result with that of the Borexino experiment to obtain 20.0{sub -8.6}{sup +8.8} TW as a contribution of {sup 238}U and {sup 232}Th to the Earth heat flow.« less

Impact of Planetary Boundary Layer Depth on Climatological Tracer Transport in the GEOS-5 AGCM

NASA Astrophysics Data System (ADS)

McGrath-Spangler, E. L.; Molod, A.

2013-12-01

Planetary boundary layer (PBL) processes have large implications for tropospheric tracer transport since surface fluxes are diluted by the depth of the PBL through vertical mixing. However, no consensus on PBL depth definition currently exists and various methods for estimating this parameter can give results that differ by hundreds of meters or more. In order to facilitate comparisons between the Goddard Earth Observation System (GEOS-5) and other modeling and observational systems, seven PBL depth estimation methods are used to diagnose PBL depth and produce climatologies that are evaluated here. All seven methods evaluate a single atmosphere so differences are related solely to the definition chosen. PBL depths that are estimated using a Richardson number are shallower than those given by methods based on the scalar diffusivity during warm, moist conditions at midday and collapse to lower values at night. In GEOS-5, the PBL depth is used in the estimation of the turbulent length scale and so impacts vertical mixing. Changing the method used to determine the PBL depth for this length scale thus changes the tracer transport. Using a bulk Richardson number method instead of a scalar diffusivity method produces changes in the quantity of Saharan dust lofted into the free troposphere and advected to North America, with more surface dust in North America during boreal summer and less in boreal winter. Additionally, greenhouse gases are considerably impacted. During boreal winter, changing the PBL depth definition produces carbon dioxide differences of nearly 5 ppm over Siberia and gradients of about 5 ppm over 1000 km in Europe. PBL depth changes are responsible for surface carbon monoxide changes of 20 ppb or more over the biomass burning regions of Africa.

Confined in-fiber solidification and structural control of silicon and silicon−germanium microparticles

PubMed Central

Gumennik, Alexander; Levy, Etgar C.; Grena, Benjamin; Hou, Chong; Rein, Michael; Abouraddy, Ayman F.; Joannopoulos, John D.; Fink, Yoel

2017-01-01

Crystallization of microdroplets of molten alloys could, in principle, present a number of possible morphological outcomes, depending on the symmetry of the propagating solidification front and its velocity, such as axial or spherically symmetric species segregation. However, because of thermal or constitutional supercooling, resulting droplets often only display dendritic morphologies. Here we report on the crystallization of alloyed droplets of controlled micrometer dimensions comprising silicon and germanium, leading to a number of surprising outcomes. We first produce an array of silicon−germanium particles embedded in silica, through capillary breakup of an alloy-core silica-cladding fiber. Heating and subsequent controlled cooling of individual particles with a two-wavelength laser setup allows us to realize two different morphologies, the first being a silicon−germanium compositionally segregated Janus particle oriented with respect to the illumination axis and the second being a sphere made of dendrites of germanium in silicon. Gigapascal-level compressive stresses are measured within pure silicon solidified in silica as a direct consequence of volume-constrained solidification of a material undergoing anomalous expansion. The ability to generate microspheres with controlled morphology and unusual stresses could pave the way toward advanced integrated in-fiber electronic or optoelectronic devices. PMID:28642348

Confined in-fiber solidification and structural control of silicon and silicon-germanium microparticles.

PubMed

Gumennik, Alexander; Levy, Etgar C; Grena, Benjamin; Hou, Chong; Rein, Michael; Abouraddy, Ayman F; Joannopoulos, John D; Fink, Yoel

2017-07-11

Crystallization of microdroplets of molten alloys could, in principle, present a number of possible morphological outcomes, depending on the symmetry of the propagating solidification front and its velocity, such as axial or spherically symmetric species segregation. However, because of thermal or constitutional supercooling, resulting droplets often only display dendritic morphologies. Here we report on the crystallization of alloyed droplets of controlled micrometer dimensions comprising silicon and germanium, leading to a number of surprising outcomes. We first produce an array of silicon-germanium particles embedded in silica, through capillary breakup of an alloy-core silica-cladding fiber. Heating and subsequent controlled cooling of individual particles with a two-wavelength laser setup allows us to realize two different morphologies, the first being a silicon-germanium compositionally segregated Janus particle oriented with respect to the illumination axis and the second being a sphere made of dendrites of germanium in silicon. Gigapascal-level compressive stresses are measured within pure silicon solidified in silica as a direct consequence of volume-constrained solidification of a material undergoing anomalous expansion. The ability to generate microspheres with controlled morphology and unusual stresses could pave the way toward advanced integrated in-fiber electronic or optoelectronic devices.

Origin of flatband voltage shift and unusual minority carrier generation in thermally grown GeO2/Ge metal-oxide-semiconductor devices

NASA Astrophysics Data System (ADS)

Hosoi, Takuji; Kutsuki, Katsuhiro; Okamoto, Gaku; Saito, Marina; Shimura, Takayoshi; Watanabe, Heiji

2009-05-01

Improvement in electrical properties of thermally grown GeO2/Ge metal-oxide-semiconductor (MOS) capacitors, such as significantly reduced flatband voltage (VFB) shift, small hysteresis, and minimized minority carrier response in capacitance-voltage (C-V) characteristics, has been demonstrated by in situ low temperature vacuum annealing prior to gate electrode deposition. Thermal desorption analysis has revealed that not only water but also hydrocarbons are easily infiltrated into GeO2 layers during air exposure and desorbed at around 300 °C, indicating that organic molecules within GeO2/Ge MOS structures are possible origins of electrical defects. The inversion capacitance, indicative of minority carrier generation, increases with air exposure time for Au/GeO2/Ge MOS capacitors, while maintaining an interface state density (Dit) of about a few 1011 cm-2 eV-1. Unusual increase in inversion capacitance was found to be suppressed by Al2O3 capping (Au/Al2O3/GeO2/Ge structures). This suggests that electrical defects induced outside the Au electrode by infiltrated molecules may enhance the minority carrier generation, and thus acting as a minority carrier source just like MOS field-effect transistors.

Solution synthesis of germanium nanowires using a Ge+2 alkoxide precursor.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyle, Timothy J.; Tribby, Louis, J; Bunge, Scott D.

2006-02-01

A simple solution synthesis of germanium (Ge{sup 0}) nanowires under mild conditions (<400 C and 1 atm) was demonstrated using germanium 2,6 dibutylphenoxide Ge(DBP){sub 2} (1) as the precursor where DBP = OC{sub 6}H{sub 3}(C(CH{sub 3}){sub 3}){sub 2}-2,6. Compound 1, synthesized from Ge(NR{sub 2}){sub 2} where R = SiMe{sub 3} and two equivalents of DBP-H, was characterized as a mononuclear species by single crystal X-ray diffraction. Dissolution of 1 in oleylamine, followed by rapid injection into a 1-octadecene solution heated to 300 C under an atmosphere of Ar, led to the formation of Ge{sup 0} nanowires. The Ge{sup 0} nanowiresmore » were characterized by transmission electron microscopy (TEM), X-ray diffraction analysis, and Fourier transform infrared spectroscopy. These characterizations revealed that the nanowires are single crystalline in the cubic phase and coated with oleylamine surfactant. We also observed that the nanowire length (0.1 to 10 {micro}m) increases with increasing temperature (285 to 315 C) and time (5 to 60 min). Two growth mechanisms are proposed based on the TEM images intermittently taken during the growth process as a function of time: (1) self-seeding mechanism where one of two overlapping nanowires serves as a seed, while the other continues to grow as a wire and (2) self-assembly mechanism where an aggregate of small rods (< 50 nm in diameter) recrystallize on the tip of a longer wire, extending its length.« less

Acquisition of a High-Resolution High-Intensity X-ray Diffractometer for Research and Education

DTIC Science & Technology

2015-07-20

NAME(S) AND ADDRESS (ES) U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 X-ray diffraction; germanium- tin alloys...is in progress for others. Comprehensive data were acquired for pseudomorphic germanium- tin alloys grown on germanium by molecular beam epitaxy...Research  100+  2000  Federal grant  Germanium‐ tin  alloys  Tech transfer  9  180  Startup company  Metallurgy  Research  5  100  Federal grant  SAXS  Total

Regimes of laser-induced periodic surface structure on germanium: radiation remnants and surface plasmons.

PubMed

Young, J F; Sipe, J E; van Driel, H M

1983-08-01

We present experimental evidence showing that the period of the rippled surface structure induced on germanium by 1.06-microm laser pulses undergoes a discontinuous shift above a certain threshold intensity. The measured shift, as a angle of incidence of the damaging beam, is quantitatively interpreted as a transition between a regime of inhomogeneous melting controlled by radiation-remnant field structures and a regime of ripple formation surface plasmons in an optically thick layer of liquid, metallic germanium formed at the surface.

Doping of germanium and silicon crystals with non-hydrogenic acceptors for far infrared lasers

DOEpatents

Haller, Eugene E.; Brundermann, Erik

2000-01-01

A method for doping semiconductors used for far infrared lasers with non-hydrogenic acceptors having binding energies larger than the energy of the laser photons. Doping of germanium or silicon crystals with beryllium, zinc or copper. A far infrared laser comprising germanium crystals doped with double or triple acceptor dopants permitting the doped laser to be tuned continuously from 1 to 4 terahertz and to operate in continuous mode. A method for operating semiconductor hole population inversion lasers with a closed cycle refrigerator.

Geostationary Coastal and Air Pollution Events (GeoCAPE) Filter Radiometer (FR)

NASA Technical Reports Server (NTRS)

Kotecki, Carl; Chu, Martha; Wilson, Mark; Clark, Mike; Nanan, Bobby; Matson, Liz; McBirney, Dick; Smith, Jay; Earle, Paul; Choi, Mike;

Germanium and indium

USGS Publications Warehouse

Shanks, W.C. Pat; Kimball, Bryn E.; Tolcin, Amy C.; Guberman, David E.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

2017-12-19

Germanium and indium are two important elements used in electronics devices, flat-panel display screens, light-emitting diodes, night vision devices, optical fiber, optical lens systems, and solar power arrays. Germanium and indium are treated together in this chapter because they have similar technological uses and because both are recovered as byproducts, mainly from copper and zinc sulfides.The world’s total production of germanium in 2011 was estimated to be 118 metric tons. This total comprised germanium recovered from zinc concentrates, from fly ash residues from coal burning, and from recycled material. Worldwide, primary germanium was recovered in Canada from zinc concentrates shipped from the United States; in China from zinc residues and coal from multiple sources in China and elsewhere; in Finland from zinc concentrates from the Democratic Republic of the Congo; and in Russia from coal.World production of indium metal was estimated to be about 723 metric tons in 2011; more than one-half of the total was produced in China. Other leading producers included Belgium, Canada, Japan, and the Republic of Korea. These five countries accounted for nearly 95 percent of primary indium production.Deposit types that contain significant amounts of germanium include volcanogenic massive sulfide (VMS) deposits, sedimentary exhalative (SEDEX) deposits, Mississippi Valley-type (MVT) lead-zinc deposits (including Irish-type zinc-lead deposits), Kipushi-type zinc-lead-copper replacement bodies in carbonate rocks, and coal deposits.More than one-half of the byproduct indium in the world is produced in southern China from VMS and SEDEX deposits, and much of the remainder is produced from zinc concentrates from MVT deposits. The Laochang deposit in Yunnan Province, China, and the VMS deposits of the Murchison greenstone belt in Limpopo Province, South Africa, provide excellent examples of indium-enriched deposits. The SEDEX deposits at Bainiuchang, China (located in southeastern Yunnan Province), and the Dabaoshan SEDEX deposit (located in the Nanling region of China) contain indium-enriched sphalerite. Another major potential source of indium occurs in the polymetallic tin-tungsten belt in the Eastern Cordillera of the Andes Mountains of Bolivia. Deposits there occur as dense arrays of narrow, elongate, indium-enriched tin oxide-polymetallic sulfide veins in volcanic rocks and porphyry stocks.Information about the behavior of germanium and indium in the environment is limited. In surface weathering environments, germanium and indium may dissolve from host minerals and form complexes with chloride, fluoride, hydroxide, organic matter, phosphate, or sulfate compounds. The tendency for germanium and indium to be dissolved and transported largely depends upon the pH and temperature of the weathering solutions. Because both elements are commonly concentrated in sulfide minerals, they can be expected to be relatively mobile in acid mine drainage where oxidative dissolution of sulfide minerals releases metals and sulfuric acid, resulting in acidic pH values that allow higher concentrations of metals to be dissolved into solution.

Limit on the radiative neutrinoless double electron capture of ^{36}Ar from GERDA Phase I

NASA Astrophysics Data System (ADS)

Agostini, M.; Allardt, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Barros, N.; Baudis, L.; Bauer, C.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Benato, G.; Bettini, A.; Bezrukov, L.; Bode, T.; Borowicz, D.; Brudanin, V.; Brugnera, R.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; D'Andrea, V.; Demidova, E. V.; di Vacri, A.; Domula, A.; Doroshkevich, E.; Egorov, V.; Falkenstein, R.; Fedorova, O.; Freund, K.; Frodyma, N.; Gangapshev, A.; Garfagnini, A.; Gooch, C.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hakenmüller, J.; Hegai, A.; Heisel, M.; Hemmer, S.; Heusser, G.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Csáthy, J. Janicskó; Jochum, J.; Junker, M.; Kazalov, V.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Kish, A.; Klimenko, A.; Kneißl, R.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lebedev, V. I.; Lehnert, B.; Liao, H. Y.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Medinaceli, E.; Miloradovic, M.; Mingazheva, R.; Misiaszek, M.; Moseev, P.; Nemchenok, I.; Palioselitis, D.; Panas, K.; Pandola, L.; Pelczar, K.; Pullia, A.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salamida, F.; Salathe, M.; Schmitt, C.; Schneider, B.; Schönert, S.; Schreiner, J.; Schütz, A.-K.; Schulz, O.; Schwingenheuer, B.; Selivanenko, O.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Stepaniuk, M.; Vanhoefer, L.; Vasenko, A. A.; Veresnikova, A.; von Sturm, K.; Wagner, V.; Walter, M.; Wegmann, A.; Wester, T.; Wiesinger, C.; Wilsenach, H.; Wojcik, M.; Yanovich, E.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zuber, K.; Zuzel, G.

2016-12-01

Neutrinoless double electron capture is a process that, if detected, would give evidence of lepton number violation and the Majorana nature of neutrinos. A search for neutrinoless double electron capture of ^{36}Ar has been performed with germanium detectors installed in liquid argon using data from Phase I of the GERmanium Detector Array ( Gerda) experiment at the Gran Sasso Laboratory of INFN, Italy. No signal was observed and an experimental lower limit on the half-life of the radiative neutrinoless double electron capture of ^{36}Ar was established: T_{1/2} > 3.6 × 10^{21} years at 90% CI.

Limit on the radiative neutrinoless double electron capture of 36Ar from GERDA Phase I

DOE PAGES

Agostini, M.; Allardt, M.; Bakalyarov, A. M.; ...

2016-11-28

Neutrinoless double electron capture is a process that, if detected, would give evidence of lepton number violation and the Majorana nature of neutrinos. Here, a search for neutrinoless double electron capture of 36Ar has been performed with germanium detectors installed in liquid argon using data from Phase I of the GERmanium Detector Array (Gerda) experiment at the Gran Sasso Laboratory of INFN, Italy. No signal was observed and an experimental lower limit on the half-life of the radiative neutrinoless double electron capture of 36 Ar was established: T 1/2 > 3.6 × 10 21 years at 90% CI.

Auger electron and X-ray photoelectron spectroscopic study of the biocorrosion of copper by alginic acid polysaccharide

NASA Astrophysics Data System (ADS)

Jolley, John G.; Geesey, Gill G.; Hankins, Michael R.; Wright, Randy B.; Wichlacz, Paul L.

1989-08-01

Thin films (3.4 nm) of copper on germanium substrates were exposed to 2% alginic acid polysaccharide aqueous solution. Pre- and post-exposure characterization were done by Auger electron spectroscopy and X-ray photoelectron spectroscopy. Ancillary graphite furnace atomic absorption spectroscopy was used to monitor the removal process of the copper thin film from the germanium substrate. Results indicate that some of the copper was oxidized by the alginic acid solution. Some of the copper was removed from the Cu/Ge interface and incorporated into the polymer matrix. Thus, biocorrosion of copper was exhibited by the alginic acid polysaccharide.

Ge14 Br8 (PEt3 )4 : A Subhalide Cluster of Germanium.

PubMed

Kunz, Tanja; Schrenk, Claudio; Schnepf, Andreas

2018-04-03

Heating a metastable solution of Ge I Br to room temperature led to the first structurally characterized metalloid subhalide cluster Ge 14 Br 8 (PEt 3 ) 4 (1). Furthermore 1 can be seen as the first isolated binary halide cluster on the way from Ge I Br to elemental germanium, giving insight into the complex reaction mechanism of its disproportionation reaction. Quantum chemical calculations further indicate that a classical bonding situation is realized within 1 and that the last step of the formation of 1 might include the trapping of GeBr 2 units. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Control of spontaneous combustion of coal in goaf at high geotemperatureby injecting liquid carbon dioxide: inertand cooling characteristics of coal

NASA Astrophysics Data System (ADS)

Liu, Zhenling; Wen, Hu; Yu, Zhijin; Wang, Chao; Ma, Li

2018-02-01

The spontaneous combustion of coal in goaf at high geo temperatures is threatening safety production in coalmine. The TG-DSC is employed to study the variation of mass and energy at 4 atmospheres (mixed gases of N2, O2 and CO2) and heating rates (10°C/min) during oxidation of coal samples. The apparent activation energy and pre-exponential factor of coal oxidation decrease rapidly with increasing theCO2 concentration. Furthermore, its reaction rate is slow, its heat released reduces. Based on the conditions of 1301 face in the Longgucoalmine, a three-dimensional geometry model is developed to simulate the distributions stream field and temperature field and the variation characteristics ofCO2 concentration field after injecting liquidCO2. The results indicate that oxygen reached to depths of˜120m in goaf, 100m in the side of inlet air, and 10m in the side of outlet air before injecting liquidCO2. After injecting liquidCO2for 28.8min, the width of oxidation and heat accumulation zone is shortened by 20m, and the distance is 80m in the side of working face and 40˜60m in goafin the direction of dip affected by temperature.

Improved retention of phosphorus donors in germanium using a non-amorphizing fluorine co-implantation technique

NASA Astrophysics Data System (ADS)

Monmeyran, Corentin; Crowe, Iain F.; Gwilliam, Russell M.; Heidelberger, Christopher; Napolitani, Enrico; Pastor, David; Gandhi, Hemi H.; Mazur, Eric; Michel, Jürgen; Agarwal, Anuradha M.; Kimerling, Lionel C.

2018-04-01

Co-doping with fluorine is a potentially promising method for defect passivation to increase the donor electrical activation in highly doped n-type germanium. However, regular high dose donor-fluorine co-implants, followed by conventional thermal treatment of the germanium, typically result in a dramatic loss of the fluorine, as a result of the extremely large diffusivity at elevated temperatures, partly mediated by the solid phase epitaxial regrowth. To circumvent this problem, we propose and experimentally demonstrate two non-amorphizing co-implantation methods; one involving consecutive, low dose fluorine implants, intertwined with rapid thermal annealing and the second, involving heating of the target wafer during implantation. Our study confirms that the fluorine solubility in germanium is defect-mediated and we reveal the extent to which both of these strategies can be effective in retaining large fractions of both the implanted fluorine and, critically, phosphorus donors.

Solder for oxide layer-building metals and alloys

DOEpatents

Kronberg, James W.

1992-01-01

A low temperature solder and method for soldering an oxide layer-building metal such as aluminum, titanium, tantalum or stainless steel. The comosition comprises tin and zinc; germanium as a wetting agent; preferably small amounts of copper and antimony; and a grit, such as silicon carbide. The grit abrades any oxide layer formed on the surface of the metal as the germanium penetrates beneath and loosens the oxide layer to provide good metal-to-metal contact. The germanium comprises less than aproximatley 10% by weight of the solder composition so that it provides sufficient wetting action but does not result in a melting temperature above approximately 300.degree. C. The method comprises the steps rubbing the solder against the metal surface so the grit in the solder abrades the surface while heating the surface until the solder begins to melt and the germanium penetrates the oxide layer, then brushing aside any oxide layer loosened by the solder.

Solder for oxide layer-building metals and alloys

DOEpatents

Kronberg, J.W.

1992-09-15

A low temperature solder and method for soldering an oxide layer-building metal such as aluminum, titanium, tantalum or stainless steel is disclosed. The composition comprises tin and zinc; germanium as a wetting agent; preferably small amounts of copper and antimony; and a grit, such as silicon carbide. The grit abrades any oxide layer formed on the surface of the metal as the germanium penetrates beneath and loosens the oxide layer to provide good metal-to-metal contact. The germanium comprises less than approximately 10% by weight of the solder composition so that it provides sufficient wetting action but does not result in a melting temperature above approximately 300 C. The method comprises the steps rubbing the solder against the metal surface so the grit in the solder abrades the surface while heating the surface until the solder begins to melt and the germanium penetrates the oxide layer, then brushing aside any oxide layer loosened by the solder.

Two-Dimensional Spatial Imaging of Charge Transport in Germanium Crystals at Cryogenic Temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moffatt, Robert

2016-03-01

In this dissertation, I describe a novel apparatus for studying the transport of charge in semiconductors at cryogenic temperatures. The motivation to conduct this experiment originated from an asymmetry observed between the behavior of electrons and holes in the germanium detector crystals used by the Cryogenic Dark Matter Search (CDMS). This asymmetry is a consequence of the anisotropic propagation of electrons in germanium at cryogenic temperatures. To better model our detectors, we incorporated this effect into our Monte Carlo simulations of charge transport. The purpose of the experiment described in this dissertation is to test those models in detail. Ourmore » measurements have allowed us to discover a shortcoming in our most recent Monte Carlo simulations of electrons in germanium. This discovery would not have been possible without the measurement of the full, two-dimensional charge distribution, which our experimental apparatus has allowed for the first time at cryogenic temperatures.« less

Argon–germane in situ plasma clean for reduced temperature Ge on Si epitaxy by high density plasma chemical vapor deposition

DOE PAGES

Douglas, Erica A.; Sheng, Josephine J.; Verley, Jason C.; ...

2015-06-04

We found that the demand for integration of near infrared optoelectronic functionality with silicon complementary metal oxide semiconductor (CMOS) technology has for many years motivated the investigation of low temperature germanium on silicon deposition processes. Our work describes the development of a high density plasma chemical vapor deposition process that uses a low temperature (<460 °C) in situ germane/argon plasma surface preparation step for epitaxial growth of germanium on silicon. It is shown that the germane/argon plasma treatment sufficiently removes SiO x and carbon at the surface to enable germanium epitaxy. Finally, the use of this surface preparation step demonstratesmore » an alternative way to produce germanium epitaxy at reduced temperatures, a key enabler for increased flexibility of integration with CMOS back-end-of-line fabrication.« less

Measurement of the quantum conductance of germanium by an electrochemical scanning tunneling microscope break junction based on a jump-to-contact mechanism.

PubMed

Xie, Xufen; Yan, Jiawei; Liang, Jinghong; Li, Jijun; Zhang, Meng; Mao, Bingwei

2013-10-01

We present quantum conductance measurements of germanium by means of an electrochemical scanning tunneling microscope (STM) break junction based on a jump-to-contact mechanism. Germanium nanowires between a platinum/iridium tip and different substrates were constructed to measure the quantum conductance. By applying appropriate potentials to the substrate and the tip, the process of heterogeneous contact and homogeneous breakage was realized. Typical conductance traces exhibit steps at 0.025 and 0.05 G0. The conductance histogram indicates that the conductance of germanium nanowires is located between 0.02 and 0.15 G0 in the low-conductance region and is free from the influence of substrate materials. However, the distribution of conductance plateaus is too discrete to display distinct peaks in the conductance histogram of the high-conductance region. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Molybdenum blue reaction and determination of phosphorus in waters containing arsenic, silicon, and germanium

USGS Publications Warehouse

Levine, H.; Rowe, J.J.; Grimaldi, F.S.

1955-01-01

Microgram amounts of phosphate are usually determined by the molybdenum blue reaction, but this reaction is not specific for phosphorus. The research established the range of conditions under which phosphate, arsenate, silicate, and germanate give the molybdenum blue reaction for differentiating these elements, and developed a method for the determination of phosphate in waters containing up to 10 p.p.m. of the oxides of germanium, arsenic(V), and silicon. With stannous chloride or 1-amino-2-naphthol-4-sulfonic acid as the reducing agent no conditions were found for distinguishing silicate from germanate and phosphate from arsenate. In the recommended procedure the phosphate is concentrated by coprecipitation on aluminum hydroxide, and coprecipitated arsenic, germanium, and silicon are volatilized by a mixture of hydrofluoric, hydrochloric, and hydrobromic acids prior to the determination of phosphate. The authors are able to report that the total phosphorus content of several samples of sea water from the Gulf of Mexico ranged from 0.018 to 0.059 mg. of phosphorus pentoxide per liter of water.

Sensitivity of Assimilated Tropical Tropospheric Ozone to the Meteorological Analyses

NASA Technical Reports Server (NTRS)

Hayashi, Hiroo; Stajner, Ivanka; Pawson, Steven; Thompson, Anne M.

2002-01-01

Tropical tropospheric ozone fields from two different experiments performed with an off-line ozone assimilation system developed in NASA's Data Assimilation Office (DAO) are examined. Assimilated ozone fields from the two experiments are compared with the collocated ozone profiles from the Southern Hemispheric Additional Ozonesondes (SHADOZ) network. Results are presented for 1998. The ozone assimilation system includes a chemistry-transport model, which uses analyzed winds from the Goddard Earth Observing System (GEOS) Data Assimilation System (DAS). The two experiments use wind fields from different versions of GEOS DAS: an operational version of the GEOS-2 system and a prototype of the GEOS-4 system. While both versions of the DAS utilize the Physical-space Statistical Analysis System and use comparable observations, they use entirely different general circulation models and data insertion techniques. The shape of the annual-mean vertical profile of the assimilated ozone fields is sensitive to the meteorological analyses, with the GEOS-4-based ozone being closest to the observations. This indicates that the resolved transport in GEOS-4 is more realistic than in GEOS-2. Remaining uncertainties include quantification of the representation of sub-grid-scale processes in the transport calculations, which plays an important role in the locations and seasons where convection dominates the transport.

GERDA: Recent results and future plans

NASA Astrophysics Data System (ADS)

Lehnert, Björn

2014-04-01

The GERmanium Detector Array (GERDA) is an experiment designed to investigate the neutrinoless double beta decay (0 νββ) in 76Ge. An array of high purity germanium detectors isotopically enriched to 87% of 76Ge is operated within 64 m3 of liquid argon (LAr) at the Laboratori Nazionali del Gran Sasso (LNGS). The experiment aims to explore the 0 νββ half-life up to 1.4×1026 yr with a collected exposure of 100 kg yr separated into two physics phases. The data taking of Phase I started in November 2011 and finished in May 2013 with 21.6 kg yr of exposure and a background index (BI) of 2×10-2cts/(kg yr keV) around the Q-value of 2039 keV before pulse shape cuts. Phase II of the experiment is being prepared with additional 30 Broad Energy Germanium (BEGe) detectors and an instrumentation of the LAr, aiming at a BI reduction by a factor of 10 w.r. to Phase I. This paper will present the GERDA setup and the latest results of the experiment including a new measurement of the 2 νββ spectrum of 76Ge and the decomposition of the background spectrum. The 0 νββ analysis, finished in the meanwhile, will be briefly mentioned. Furthermore, the major improvements planned for Phase II will be discussed.

Unique Urchin-like Ca2Ge7O16 Hierarchical Hollow Microspheres as Anode Material for the Lithium Ion Battery.

PubMed

Li, Dan; Feng, Chuanqi; Liu, Hua Kun; Guo, Zaiping

2015-06-10

Germanium is an outstanding anode material in terms of electrochemical performance, especially rate capability, but its developments are hindered by its high price because it is rare in the crust of earth, and its huge volume variation during the lithium insertion and extraction. Introducing other cheaper elements into the germanium-based material is an efficient way to dilute the high price, but normally sacrifice its electrochemical performance. By the combination of nanostructure design and cheap element (calcium) introduction, urchin-like Ca2Ge7O16 hierarchical hollow microspheres have been successfully developed in order to reduce the price and maintain the good electrochemical properties of germanium-based material. The electrochemical test results in different electrolytes show that ethylene carbonate/dimethyl carbonate/diethyl carbonate (3/4/3 by volume) with 5 wt% fluoroethylene carbonate additive is the most suitable solvent for the electrolyte. From the electrochemical evaluation, the as-synthesized Ca2Ge7O16 hollow microspheres exhibit high reversible specific capacity of up to 804.6 mA h g(-1) at a current density of 100 mA g(-1) after 100 cycles and remarkable rate capability of 341.3 mA h g(-1) at a current density of 4 A g(-1). The growth mechanism is proposed based on our experimental results on the growth process.

GeoCorps America

NASA Astrophysics Data System (ADS)

Dawson, M.

2011-12-01

GeoCorps America, a program of the Geological Society of America's (GSA) Education and Outreach Department, provides short-term geoscience jobs in America's most amazing public lands. These jobs are hosted on federal lands managed by GeoCorps' three partner agencies: the National Park Service (NPS), the U.S. Forest Service (USFS), and the Bureau of Land Management (BLM). Agency staff submit to GSA position descriptions that help meet their geoscience needs. GSA advertises the positions online, recruits applicants from its 24,000+ members, and coordinates the placement of the candidates selected by agency staff. The typical GeoCorps position lasts for three months, pays a stipend of $2,750, and provides either free housing or a housing allowance. Some GeoCorps positions are classified as "Guest Scientist" positions, which generally last longer, involve larger payments, and require a higher level of expertise. Most GeoCorps positions occur during the spring/summer, but an increasing number of positions are being offered during the fall/winter. GeoCorps positions are open to geoscientists of all levels, from undergraduates through retired professionals. GeoCorps projects involve field and laboratory-based geoscience research, but some projects focus on developing educational programs and materials for staff, volunteers, and the public. The subject areas covered by GeoCorps projects include geology, hydrology, paleontology, mapping/GIS, soils, geo-hazards, cave/karst science, and more. GeoCorps positions have taken place at over 125 different locations nationwide, including Grand Canyon National Park, Sierra National Forest, and Craters of the Moon National Monument. In 2011, GeoCorps began offering GeoCorps Diversity Internships and GeoCorps American Indian Internships. The introduction of these programs doubled the level of diversity among GeoCorps participants. This increase in diversity is helping GSA and its partner agencies in meeting its mutual goal of broadening participation in the field of geoscience. Over the next few years, GeoCorps aims to further increase its diversity, add more partner groups (such as USGS), and continue to provide inspiring educational and professional development opportunities for geoscientists of all levels.

Ultrafast carrier thermalization and trapping in silicon-germanium alloy probed by extreme ultraviolet transient absorption spectroscopy

PubMed Central

Zürch, Michael; Chang, Hung-Tzu; Kraus, Peter M.; Cushing, Scott K.; Borja, Lauren J.; Gandman, Andrey; Kaplan, Christopher J.; Oh, Myoung Hwan; Prell, James S.; Prendergast, David; Pemmaraju, Chaitanya D.; Neumark, Daniel M.; Leone, Stephen R.

2017-01-01

Semiconductor alloys containing silicon and germanium are of growing importance for compact and highly efficient photonic devices due to their favorable properties for direct integration into silicon platforms and wide tunability of optical parameters. Here, we report the simultaneous direct and energy-resolved probing of ultrafast electron and hole dynamics in a silicon-germanium alloy with the stoichiometry Si0.25Ge0.75 by extreme ultraviolet transient absorption spectroscopy. Probing the photoinduced dynamics of charge carriers at the germanium M4,5-edge (∼30 eV) allows the germanium atoms to be used as reporter atoms for carrier dynamics in the alloy. The photoexcitation of electrons across the direct and indirect band gap into conduction band (CB) valleys and their subsequent hot carrier relaxation are observed and compared to pure germanium, where the Ge direct (ΔEgap,Ge,direct=0.8 eV) and Si0.25Ge0.75 indirect gaps (ΔEgap,Si0.25Ge0.75,indirect=0.95 eV) are comparable in energy. In the alloy, comparable carrier lifetimes are observed for the X, L, and Γ valleys in the conduction band. A midgap feature associated with electrons accumulating in trap states near the CB edge following intraband thermalization is observed in the Si0.25Ge0.75 alloy. The successful implementation of the reporter atom concept for capturing the dynamics of the electronic bands by site-specific probing in solids opens a route to study carrier dynamics in more complex materials with femtosecond and sub-femtosecond temporal resolution. PMID:28653020

Induced Radioactivity Measured in a Germanium Detector After a Long Duration Balloon Flight

NASA Technical Reports Server (NTRS)

Starr, R.; Evans, L. G.; Floyed, S. R.; Drake, D. M.; Feldman, W. C.; Squyres, S. W.; Rester, A. C.

1997-01-01

A 13-day long duration balloon flight carrying a germanium detector was flown from Williams Field, Antartica in December 1992. After recovery of the payload the activity induced in the detector was measured.

Evaluating a 3-D transport model of atmospheric CO2 using ground-based, aircraft, and space-borne data

NASA Astrophysics Data System (ADS)

Feng, L.; Palmer, P. I.; Yang, Y.; Yantosca, R. M.; Kawa, S. R.; Paris, J.-D.; Matsueda, H.; Machida, T.

2011-03-01

We evaluate the GEOS-Chem atmospheric transport model (v8-02-01) of CO2 over 2003-2006, driven by GEOS-4 and GEOS-5 meteorology from the NASA Goddard Global Modeling and Assimilation Office, using surface, aircraft and space-borne concentration measurements of CO2. We use an established ensemble Kalman Filter to estimate a posteriori biospheric+biomass burning (BS + BB) and oceanic (OC) CO2 fluxes from 22 geographical regions, following the TransCom-3 protocol, using boundary layer CO2 data from a subset of GLOBALVIEW surface sites. Global annual net BS + BB + OC CO2 fluxes over 2004-2006 for GEOS-4 (GEOS-5) meteorology are -4.4 ± 0.9 (-4.2 ± 0.9), -3.9 ± 0.9 (-4.5 ± 0.9), and -5.2 ± 0.9 (-4.9 ± 0.9) PgC yr-1, respectively. After taking into account anthropogenic fossil fuel and bio-fuel emissions, the global annual net CO2 emissions for 2004-2006 are estimated to be 4.0 ± 0.9 (4.2 ± 0.9), 4.8 ± 0.9 (4.2 ± 0.9), and 3.8 ± 0.9 (4.1 ± 0.9) PgC yr-1, respectively. The estimated 3-yr total net emission for GEOS-4 (GEOS-5) meteorology is equal to 12.5 (12.4) PgC, agreeing with other recent top-down estimates (12-13 PgC). The regional a posteriori fluxes are broadly consistent in the sign and magnitude of the TransCom-3 study for 1992-1996, but we find larger net sinks over northern and southern continents. We find large departures from our a priori over Europe during summer 2003, over temperate Eurasia during 2004, and over North America during 2005, reflecting an incomplete description of terrestrial carbon dynamics. We find GEOS-4 (GEOS-5) a posteriori CO2 concentrations reproduce the observed surface trend of 1.91-2.43 ppm yr-1 (parts per million per year), depending on latitude, within 0.15 ppm yr-1 (0.2 ppm yr-1) and the seasonal cycle within 0.2 ppm (0.2 ppm) at all latitudes. We find the a posteriori model reproduces the aircraft vertical profile measurements of CO2 over North America and Siberia generally within 1.5 ppm in the free and upper troposphere but can be biased by up to 4-5 ppm in the boundary layer at the start and end of the growing season. The model has a small negative bias in the free troposphere CO2 trend (1.95-2.19 ppm yr-1) compared to AIRS data which has a trend of 2.21-2.63 ppm yr-1 during 2004-2006, consistent with surface data. Model CO2 concentrations in the upper troposphere, evaluated using CONTRAIL (Comprehensive Observation Network for TRace gases by AIrLiner) aircraft measurements, reproduce the magnitude and phase of the seasonal cycle of CO2 in both hemispheres. We generally find that the GEOS meteorology reproduces much of the observed tropospheric CO2 variability, suggesting that these meteorological fields will help make significant progress in understanding carbon fluxes as more data become available.

Impact of aerosol microphysics on cloud optical properties and implications to atmospheric oxidation capacity

NASA Astrophysics Data System (ADS)

Luo, G.; Yu, F.

2016-12-01

GEOS-Chem, presently used by many research groups, is a state-of-the-art global 3-D model of atmospheric composition driven by assimilated meteorology from the Goddard Earth Observing System. Our comparisons of GEOS-5 cloud properties, used in photolysis rate calculation, with MODIS retrievals show that GEOS-5 underestimates cloud optical depth (COD) by a factor of more than 2 over most regions. Our further analysis indicates that the COD underestimation in the released GEOS-5 meteorology products is likely to be associated with the fact that the GEOS-5 doesn't take into account the impact of aerosol on cloud microphysics and optical properties. A new COD parameterization (called NewC thereafter), which re-calculates COD from GEOS-5 water content and GEOS-Chem simulated size-resolved particle properties, cloud condensation nuclei abundance, and cloud droplet number concentration, has been developed and incorporated into GEOS-Chem. The NewC increases the GEOS-5 derived annual mean CODs averaged between 60ºS and 60ºN from 2.0 to 4.3, in much better agreement with corresponding MODIS value of 4.3. The enhanced COD based on NewC scheme reduces global average boundary layer OH concentration by 9.8%. Zonal averaged OH is increased 3-7% above clouds due to backscattering and decreased 10-15% below clouds due to the attenuation of solar radiation. The global mean OH concentration simulated by GEOS-Chem driven by GEOS-5 COD and NewC COD are respectively12.9 × 105molec cm-3 and 12.2 × 105molec cm-3, with the latter closer to the ACCMIP multi-model estimation (11.7±1 105molec cm-3). Surface OH concentrations over major anthropogenic regions such as Eastern US, Europe, and East Asia decrease by up to -18.6%, -14.4%, and -19.9%, respectively. The relative change of surface OH concentration appears to be the largest over the Amazon rainforest, reaching up to -30%. After switching from old COD to NewC COD, GEOS-Chem simulated column HCHO and surface isoprene over Amazon region are enhanced 12% and 20%, respectively. At the Eastern United States, column HCHO and surface isoprene are enhanced 5% and 15%, respectively. Seasonal variation and regional characteristics of the impact of aerosol microphysics on cloud properties and implications to atmospheric oxidation capacity and tropospheric compositions will be discussed.

GeoSciML and EarthResourceML Update, 2012

NASA Astrophysics Data System (ADS)

Richard, S. M.; Commissionthe Management; Application Inte, I.

2012-12-01

CGI Interoperability Working Group activities during 2012 include deployment of services using the GeoSciML-Portrayal schema, addition of new vocabularies to support properties added in version 3.0, improvements to server software for deploying services, introduction of EarthResourceML v.2 for mineral resources, and collaboration with the IUSS on a markup language for soils information. GeoSciML and EarthResourceML have been used as the basis for the INSPIRE Geology and Mineral Resources specifications respectively. GeoSciML-Portrayal is an OGC GML simple-feature application schema for presentation of geologic map unit, contact, and shear displacement structure (fault and ductile shear zone) descriptions in web map services. Use of standard vocabularies for geologic age and lithology enables map services using shared legends to achieve visual harmonization of maps provided by different services. New vocabularies have been added to the collection of CGI vocabularies provided to support interoperable GeoSciML services, and can be accessed through http://resource.geosciml.org. Concept URIs can be dereferenced to obtain SKOS rdf or html representations using the SISSVoc vocabulary service. New releases of the FOSS GeoServer application greatly improve support for complex XML feature schemas like GeoSciML, and the ArcGIS for INSPIRE extension implements similar complex feature support for ArcGIS Server. These improved server implementations greatly facilitate deploying GeoSciML services. EarthResourceML v2 adds features for information related to mining activities. SoilML provides an interchange format for soil material, soil profile, and terrain information. Work is underway to add GeoSciML to the portfolio of Open Geospatial Consortium (OGC) specifications.

Sensitivity of Photolysis Frequencies and Key Tropospheric Oxidants in a Global Model to Cloud Vertical Distributions and Optical Properties

NASA Technical Reports Server (NTRS)

Liu, Hongyu; Crawford, James H.; Considine, David B.; Platnick, Steven; Norris, Peter M.; Duncan, Bryan N.; Pierce, Robert B.; Chen, Gao; Yantosca, Robert M.

2009-01-01

Clouds affect tropospheric photochemistry through modification of solar radiation that determines photolysis frequencies. As a follow-up study to our recent assessment of the radiative effects of clouds on tropospheric chemistry, this paper presents an analysis of the sensitivity of such effects to cloud vertical distributions and optical properties (cloud optical depths (CODs) and cloud single scattering albedo), in a global 3-D chemical transport model (GEOS-Chem). GEOS-Chem was driven with a series of meteorological archives (GEOS1- STRAT, GEOS-3 and GEOS-4) generated by the NASA Goddard Earth Observing System data assimilation system. Clouds in GEOS1-STRAT and GEOS-3 have more similar vertical distributions (with substantially smaller CODs in GEOS1-STRAT) while those in GEOS-4 are optically much thinner in the tropical upper troposphere. We find that the radiative impact of clouds on global photolysis frequencies and hydroxyl radical (OH) is more sensitive to the vertical distribution of clouds than to the magnitude of column CODs. With random vertical overlap for clouds, the model calculated changes in global mean OH (J(O1D), J(NO2)) due to the radiative effects of clouds in June are about 0.0% (0.4%, 0.9%), 0.8% (1.7%, 3.1%), and 7.3% (4.1%, 6.0%), for GEOS1-STRAT, GEOS-3 and GEOS-4, respectively; the geographic distributions of these quantities show much larger changes, with maximum decrease in OH concentrations of approx.15-35% near the midlatitude surface. The much larger global impact of clouds in GEOS-4 reflects the fact that more solar radiation is able to penetrate through the optically thin upper-tropospheric clouds, increasing backscattering from low-level clouds. Model simulations with each of the three cloud distributions all show that the change in the global burden of ozone due to clouds is less than 5%. Model perturbation experiments with GEOS-3, where the magnitude of 3-D CODs are progressively varied from -100% to 100%, predict only modest changes (<5%) in global mean OH concentrations. J(O1D), J(NO2) and OH3 concentrations show the strongest sensitivity for small CODs and become insensitive at large CODs due to saturation effects. Caution should be exercised not to use in photochemical models a value for cloud single scattering albedo lower than about 0.999 in order to be consistent with the current knowledge of cloud absorption at the ultraviolet wavelengths.

Behaviors of Zn2GeO4 under high pressure and high temperature

NASA Astrophysics Data System (ADS)

Shu-Wen, Yang; Fang, Peng; Wen-Tao, Li; Qi-Wei, Hu; Xiao-Zhi, Yan; Li, Lei; Xiao-Dong, Li; Duan-Wei, He

2016-07-01

The structural stability of Zn2GeO4 was investigated by in-situ synchrotron radiation angle dispersive x-ray diffraction. The pressure-induced amorphization is observed up to 10 GPa at room temperature. The high-pressure and high-temperature sintering experiments and the Raman spectrum measurement firstly were performed to suggest that the amorphization is caused by insufficient thermal energy and tilting Zn-O-Ge and Ge-O-Ge bond angles with increasing pressure, respectively. The calculated bulk modulus of Zn2GeO4 is 117.8 GPa from the pressure-volume data. In general, insights into the mechanical behavior and structure evolution of Zn2GeO4 will shed light on the micro-mechanism of the materials variation under high pressure and high temperature. Project supported by the Joint Fund of the National Natural Science Foundation of China and Chinese Academy of Sciences (Grant No. U1332104).

Satellite thermal storage systems using metallic phase-change materials

NASA Astrophysics Data System (ADS)

Lauf, R. J.; Hamby, C.

Solar (thermal) dynamic power systems for satellites require a heat storage system capable of operating the engine during eclipse. A system is described in which the phase-change material (PCM) is a metal rather than the more conventional fluoride salts. Thermal storage modules consisting of germanium contained in graphite have good thermal conductivity, low parasitic mass, and are physically and chemically stable. The result is described for thermal cycle testing of graphite capsules containing germanium and several germanium- and silicon-based alloys, as well as some initial tests of the compatibility of graphite with Nb-1 percent Zr structural materials.

Multiple-step preparation and physicochemical characterization of crystalline α-germanium hydrogenphosphate

NASA Astrophysics Data System (ADS)

Romano, Ricardo; Ruiz, Ana I.; Alves, Oswaldo L.

2004-04-01

The reaction between germanium oxide and phosphoric acid has previously been described and led to impure germanium hydrogenphosphate samples with low crystallinity. A new multiple-step route involving the same reaction under refluxing and soft hydrothermal conditions is described for the preparation of pure and crystalline α-GeP. The physicochemical characterization of the samples allows accompaniment of the reaction evolution as well as determining short- and long-range structural organization. The phase purity of the α-GeP sample was confirmed by applying Rietveld's profile analysis, which also determined the cell parameters of its crystals.

Ultrasmall Fe2GeO4 nanodots anchored on interconnected carbon nanosheets as high-performance anode materials for lithium and sodium ion batteries

NASA Astrophysics Data System (ADS)

Han, Jinzhi; Qin, Jian; Guo, Lichao; Qin, Kaiqiang; Zhao, Naiqin; Shi, Chunsheng; Liu, Enzuo; He, Fang; Ma, Liying; He, Chunnian

2018-01-01

Poor intrinsic conductivity and huge volume expansion during charge/discharge process greatly limit the development of Ge-based ternary oxide as anode material for both lithium-ion batteries and sodium-ion batteries. To alleviate these issues, an ideal strategy is developed to achieve active particle nanocrystallization and composite with conductive carbon materials, simultaneously. Therefore, ultrasmall Fe2GeO4 nanodots (∼4.6 nm) uniformly and tightly anchored on 3D interconnected N-doped ultrathin carbon nanosheets (3D Fe2GeO4/N-CNSs) were constructed via one-step high temperature calcination process. This unique hybrid nanostructure can not only effectively enhance electron conductivity but also restrict the aggregation and volume fluctuation of Fe2GeO4 during the charge/discharge process. As a result, the 3D Fe2GeO4/N-CNSs electrode exhibited excellent electrochemical performances for both lithium-ion and sodium-ion battery anodes. When utilized for lithium-ion battery anode, the electrode delivered a highly reversible specific capacity (1280 mA h g-1 at 0.4 A g-1 after 180 cycles). It is the first time that Fe2GeO4 was applied for sodium-ion battery anode, which showed a remarkable rate capability (350 mA h g-1 at 0.1 A g-1 and 180 mA h g-1 at 22.8 A g-1), and ultralong cycling stability (∼86% reversible capacity retention after 6000 cycles).

ExoGeoLab Pilot Project for Landers, Rovers and Instruments

NASA Astrophysics Data System (ADS)

Foing, Bernard

2010-05-01

We have developed a pilot facility with a Robotic Test Bench (ExoGeoLab) and a Mobile Lab Habitat (ExoHab). They can be used to validate concepts and external instruments from partner institutes. The ExoGeoLab research incubator project, has started in the frame of a collaboration between ILEWG (International Lunar Exploration working Group http://sci.esa.int/ilewg), ESTEC, NASA and academic partners, supported by a design and control desk in the European Space Incubator (ESI), as well as infrastructure. ExoGeoLab includes a sequence of technology and research pilot project activities: - Data analysis and interpretation of remote sensing and in-situ data, and merging of multi-scale data sets - Procurement and integration of geophysical, geo-chemical and astrobiological breadboard instruments on a surface station and rovers - Integration of cameras, environment and solar sensors, Visible and near IR spectrometer, Raman spectrometer, sample handling, cooperative rovers - Delivery of a generic small planetary lander demonstrator (ExoGeoLab lander, Sept 2009) as a platform for multi-instruments tests - Research operations and exploitation of ExoGeoLab test bench for various conceptual configurations, and support for definition and design of science surface packages (Moon, Mars, NEOs, outer moons) - Field tests of lander, rovers and instruments in analogue sites (Utah MDRS 2009 & 2010, Eifel volcanic park in Sept 2009, and future campaigns). Co-authors, ILEWG ExoGeoLab & ExoHab Team: B.H. Foing(1,11)*#, C. Stoker(2,11)*, P. Ehrenfreund(10,11), L. Boche-Sauvan(1,11)*, L. Wendt(8)*, C. Gross(8, 11)*, C. Thiel(9)*, S. Peters(1,6)*, A. Borst(1,6)*, J. Zavaleta(2)*, P. Sarrazin(2)*, D. Blake(2), J. Page(1,4,11), V. Pletser(5,11)*, E. Monaghan(1)*, P. Mahapatra(1)#, A. Noroozi(3), P. Giannopoulos(1,11) , A. Calzada(1,6,11), R. Walker(7), T. Zegers(1, 15) #, G. Groemer(12)# , W. Stumptner(12)#, B. Foing(2,5), J. K. Blom(3)#, A. Perrin(14)#, M. Mikolajczak(14)#, S. Chevrier(14)#, S. Direito(6)#, S. Voute (15)#, A. Olmedo-Soler(17)#, T. E. Zegers(1, 15)#, D. Scheer(12)#, K. Bickert(12)#, D. Schildhammer(12)#, B. Jantscher(1, 11, 12)#, MECA Team(6)#, ExoGeoLab ILEWG ExoHab teams(1,4,11) EuroGeoMars team(1,4,5); 1)ESTEC/SRE-S Postbus 299, 2200 AG Noordwijk, NL, 2)NASA Ames , 3)Delft TU , 4)ESTEC TEC Technology Dir., 5)ESTEC HSF Human Spaceflight, 6)VU Amsterdam, 7)ESTEC Education Office, 8)FU Berlin, 9)Max Planck Goettingen, 10)Leiden/GWU , 11)ILEWG ExoHab Team, 12)Austrian Space Forum (OEWF Innsbruck); 14) Ecole de l'Air, Salons de Provence, 15) Utrecht U., 16) MECA Team, 17) Olmedo Knowledge Systems S.L.; * EuroGeoMars Utah crew , # ILEWG Eifel crew, EuroMoonMars/DOMMEX Utah crew.

Arcing in Leo and Geo Simulated Environments: Comparative Analysis

NASA Technical Reports Server (NTRS)

Vayner, Boris V.; Ferguson, Dale C.; Galofaro, Joel TY.

2006-01-01

Comprehensive tests of two solar array samples in simulated Low Earth Orbit (LEO) and Geosynchronous Orbit (GEO) environments have demonstrated that the arc inception voltage was 2-3 times lower in the LEO plasma than in the GEO vacuum. Arc current pulse wave forms are also essentially different in these environments. Moreover, the wide variations of pulse forms do not allow introducing the definition of a "standard arc wave form" even in GEO conditions. Visual inspection of the samples after testing in a GEO environment revealed considerable damage on coverglass surfaces and interconnects. These harmful consequences can be explained by the discharge energy being one order of magnitude higher in vacuum than in background plasma. The tests also revealed a potential danger of powerful electrostatic discharges that could be initiated on the solar array surface of a satellite in GEO during the ignition of an arcjet thruster.

The Small Size Debris Population at GEO from Optical Observations

NASA Technical Reports Server (NTRS)

Seitzer, Patrick; Barker, Ed; Buckalew, Brent; Burkhardt, Andrew; Cowardin, Heather; Frith, James; Kaleida, Catherine; Lederer, Susan M.; Lee, Chris H.

2017-01-01

We have observed the geosynchronous orbit (GEO) debris population at sizes smaller than 10 cm using optical observations with the 6.5-m Magellan telescope 'Walter Baade' at the Las Campanas Observatory in Chile. The IMACS f/2 imaging camera with a 0.5-degree diameter field of view has been used in small area surveys of the GEO regime to study the population of optically faint GEO debris. The goal is to estimate the population of GEO debris that is fainter than can be studied with 1-meter class telescopes. A significant population of objects fainter than R = 19th magnitude has been found. These objects have observed with angular rates consistent with circular orbits and orbital inclinations up to 15 degrees at GEO. A sizeable number of these objects have significant brightness variations ("flashes") during the 5-second exposure, which suggest rapid changes in the albedo-projected size product.

Interfacial band alignment and structural properties of nanoscale TiO2 thin films for integration with epitaxial crystallographic oriented germanium

NASA Astrophysics Data System (ADS)

Jain, N.; Zhu, Y.; Maurya, D.; Varghese, R.; Priya, S.; Hudait, M. K.

2014-01-01

We have investigated the structural and band alignment properties of nanoscale titanium dioxide (TiO2) thin films deposited on epitaxial crystallographic oriented Ge layers grown on (100), (110), and (111)A GaAs substrates by molecular beam epitaxy. The TiO2 thin films deposited at low temperature by physical vapor deposition were found to be amorphous in nature, and high-resolution transmission electron microscopy confirmed a sharp heterointerface between the TiO2 thin film and the epitaxially grown Ge with no traceable interfacial layer. A comprehensive assessment on the effect of substrate orientation on the band alignment at the TiO2/Ge heterointerface is presented by utilizing x-ray photoelectron spectroscopy and spectroscopic ellipsometry. A band-gap of 3.33 ± 0.02 eV was determined for the amorphous TiO2 thin film from the Tauc plot. Irrespective of the crystallographic orientation of the epitaxial Ge layer, a sufficient valence band-offset of greater than 2 eV was obtained at the TiO2/Ge heterointerface while the corresponding conduction band-offsets for the aforementioned TiO2/Ge system were found to be smaller than 1 eV. A comparative assessment on the effect of Ge substrate orientation revealed a valence band-offset relation of ΔEV(100) > ΔEV(111) > ΔEV(110) and a conduction band-offset relation of ΔEC(110) > ΔEC(111) > ΔEC(100). These band-offset parameters are of critical importance and will provide key insight for the design and performance analysis of TiO2 for potential high-κ dielectric integration and for future metal-insulator-semiconductor contact applications with next generation of Ge based metal-oxide field-effect transistors.

GeSn Based Near and Mid Infrared Heterostructure Detectors

DTIC Science & Technology

2018-02-07

prestigious journals. 15.  SUBJECT TERMS Plasmonic Enhancement, Metal Nanostructures, CMOS, Photodetectors, Germanium- Tin Diode, IR Focal Plane Array...can be achieved by using current developed chemical vapor deposition technique. Optical properties of germanium tin (Ge1-xSnx) alloys have been

Electron tunnelling into amorphous germanium and silicon.

NASA Technical Reports Server (NTRS)

Smith, C. W.; Clark, A. H.

1972-01-01

Measurements of tunnel conductance versus bias, capacitance versus bias, and internal photoemission were made in the systems aluminum-oxide-amorphous germanium and aluminium-oxide-amorphous silicon. A function was extracted which expresses the deviation of these systems from the aluminium-oxide-aluminium system.

Electron beam recrystallization of amorphous semiconductor materials

NASA Technical Reports Server (NTRS)

Evans, J. C., Jr.

1968-01-01

Nucleation and growth of crystalline films of silicon, germanium, and cadmium sulfide on substrates of plastic and glass were investigated. Amorphous films of germanium, silicon, and cadmium sulfide on amorphous substrates of glass and plastic were converted to the crystalline condition by electron bombardment.

Design, Implementation and Applications of 3d Web-Services in DB4GEO

NASA Astrophysics Data System (ADS)

Breunig, M.; Kuper, P. V.; Dittrich, A.; Wild, P.; Butwilowski, E.; Al-Doori, M.

2013-09-01

The object-oriented database architecture DB4GeO was originally designed to support sub-surface applications in the geo-sciences. This is reflected in DB4GeO's geometric data model as well as in its import and export functions. Initially, these functions were designed for communication with 3D geological modeling and visualization tools such as GOCAD or MeshLab. However, it soon became clear that DB4GeO was suitable for a much wider range of applications. Therefore it is natural to move away from a standalone solution and to open the access to DB4GeO data by standardized OGC web-services. Though REST and OGC services seem incompatible at first sight, the implementation in DB4GeO shows that OGC-based implementation of web-services may use parts of the DB4GeO-REST implementation. Starting with initial solutions in the history of DB4GeO, this paper will introduce the design, adaptation (i.e. model transformation), and first steps in the implementation of OGC Web Feature (WFS) and Web Processing Services (WPS), as new interfaces to DB4GeO data and operations. Among its capabilities, DB4GeO can provide data in different data formats like GML, GOCAD, or DB3D XML through a WFS, as well as its ability to run operations like a 3D-to-2D service, or mesh-simplification (Progressive Meshes) through a WPS. We then demonstrate, an Android-based mobile 3D augmented reality viewer for DB4GeO that uses the Web Feature Service to visualize 3D geo-database query results. Finally, we explore future research work considering DB4GeO in the framework of the research group "Computer-Aided Collaborative Subway Track Planning in Multi-Scale 3D City and Building Models".

Using GeoRePORT to report socio-economic potential for geothermal development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, Katherine R.; Levine, Aaron

The Geothermal Resource Portfolio Optimization and Reporting Tool (GeoRePORT, http://en.openei.org/wiki/GeoRePORT) was developed for reporting resource grades and project readiness levels, providing the U.S. Department of Energy a consistent and comprehensible means of evaluating projects. The tool helps funding organizations (1) quantitatively identify barriers, (2) develop measureable goals, (3) objectively evaluate proposals, including contribution to goals, (4) monitor progress, and (5) report portfolio performance. GeoRePORT assesses three categories: geological, technical, and socio-economic. Here, we describe GeoRePORT, then focus on the socio-economic assessment and its applications for assessing deployment potential in the U.S. Socio-economic attributes include land access, permitting, transmission, and market.

Air pollution and asthma severity in adults

PubMed Central

Rage, Estelle; Siroux, Valérie; Künzli, Nino; Pin, Isabelle; Kauffmann, Francine

2009-01-01

Objectives There is evidence that exposure to air pollution affects asthma, but the effect of air pollution on asthma severity has not been addressed. The aim was to assess the relation between asthma severity during the past 12 months and home outdoor concentrations of air pollution. Methods Asthma severity over the last 12 months was assessed in two complementary ways among 328 adult asthmatics from the French Epidemiological study on the Genetics and Environment of Asthma (EGEA) examined between 1991 and 1995. The 4-class severity score integrated clinical events and type of treatment. The 5-level asthma score is based only on the occurrence of symptoms. Nitrogen dioxide (NO2), sulphur dioxide (SO2) and ozone (O3) concentrations were assigned to each residence using two different methods. The first was based on the closest monitor data from 1991–1995. The second consisted in spatial models that used geostatistical interpolations and then assigned air pollutants to the geo-coded residences (1998). Results Higher asthma severity score was significantly related to the 8-hour average of ozone during April-September (O3-8hr) and the number of days (O3-days) with 8-hour ozone averages above 110 μg.m−3 (for a 36-day increase, equivalent to the inter quartile range, in O3-days, odds ratio (95% confidence interval) 2.22 (1.61–3.07) for one class difference in score). Adjustment for age, sex, smoking habits, occupational exposure, and educational level did not alter results. Asthma severity was unrelated to NO2. Both exposure assessment methods and severity scores resulted in very similar findings. SO2 correlated with severity but reached statistical significance only for the model based assignment of exposure. Conclusions The observed associations between asthma severity and air pollution, in particular O3, support the hypothesis that air pollution at levels far below current standards increases asthma severity. PMID:19017701

Technical Report Series on Global Modeling and Data Assimilation. Volume 14; A Comparison of GEOS Assimilated Data with FIFE Observations

NASA Technical Reports Server (NTRS)

Bosilovich, Michael G.; Suarez, Max J. (Editor); Schubert, Siegfried D.

1998-01-01

First ISLSCP Field Experiment (FIFE) observations have been used to validate the near-surface proper- ties of various versions of the Goddard Earth Observing System (GEOS) Data Assimilation System. The site- averaged FIFE data set extends from May 1987 through November 1989, allowing the investigation of several time scales, including the annual cycle, daily means and diurnal cycles. Furthermore, the development of the daytime convective planetary boundary layer is presented for several days. Monthly variations of the surface energy budget during the summer of 1988 demonstrate the affect of the prescribed surface soil wetness boundary conditions. GEOS data comes from the first frozen version of the assimilation system (GEOS-1 DAS) and two experimental versions of GEOS (v. 2.0 and 2.1) with substantially greater vertical resolution and other changes that influence the boundary layer. This report provides a baseline for future versions of the GEOS data assimilation system that will incorporate a state-of-the-art land surface parameterization. Several suggestions are proposed to improve the generality of future comparisons. These include the use of more diverse field experiment observations and an estimate of gridpoint heterogeneity from the new land surface parameterization.

Effect of Ge-GeO2 co-doping on non-ohmic behaviour of TiO2-V2O5-Y2O3 varistor ceramics

NASA Astrophysics Data System (ADS)

Kunyong, Kang; Guoyou, Gan; Jikang, Yan; Jianhong, Yi; Jiamin, Zhang; Jinghong, Du; Wenchao, Zhao; Xuequan, Rong

2015-07-01

An investigation was made into the effect of doping with the elemental crystal Ge or/and GeO2 on the TiO2-V2O5-Y2O3 varistor ceramics. The result shows that as the doping contents of V2O5 and Y2O3 are 0.5 mol%, respectively, co-doping with 0.3 mol% Ge and 0.9 mol% GeO2 makes the highest α value (α = 12.8), the lowest breakdown voltage V1mA (V1mA = 15.8 V/mm) and the highest grain boundary barrier ΦB (ΦB = 1.48 eV), which is remarkably superior to the TiO2-V2O5-Y2O3 varistor ceramics undoped with Ge and GeO2 and mono-doped with Ge or GeO2. The TiO2-V2O5-Y2O3-Ge-GeO2 ceramic has the prospect of becoming a novel varistor ceramic with excellent electrical properties. Project supported by the National Natural Science Foundation of China (Nos. 51262017, 51362017).

Ultrafast carrier thermalization and trapping in silicon-germanium alloy probed by extreme ultraviolet transient absorption spectroscopy

DOE PAGES

Zürch, Michael; Chang, Hung-Tzu; Kraus, Peter M.; ...

2017-06-06

Semiconductor alloys containing silicon and germanium are of growing importance for compact and highly efficient photonic devices due to their favorable properties for direct integration into silicon platforms and wide tunability of optical parameters. Here, we report the simultaneous direct and energy-resolved probing of ultrafast electron and hole dynamics in a silicon-germanium alloy with the stoichiometry Si 0.25Ge 0.75 by extreme ultraviolet transient absorption spectroscopy. Probing the photoinduced dynamics of charge carriers at the germanium M 4,5-edge (~30 eV) allows the germanium atoms to be used as reporter atoms for carrier dynamics in the alloy. The photoexcitation of electrons acrossmore » the direct and indirect band gap into conduction band (CB) valleys and their subsequent hot carrier relaxation are observed and compared to pure germanium, where the Ge direct (ΔE gap,Ge,direct = 0.8 eV) and Si 0.25Ge 0.75 indirect gaps (ΔE gap,Si0.25Ge0.75,indirect = 0.95 eV) are comparable in energy. In the alloy, comparable carrier lifetimes are observed for the X, L, and Γ valleys in the conduction band. A midgap feature associated with electrons accumulating in trap states near the CB edge following intraband thermalization is observed in the Si 0.25Ge 0.75 alloy. The successful implementation of the reporter atom concept for capturing the dynamics of the electronic bands by site-specific probing in solids opens a route to study carrier dynamics in more complex materials with femtosecond and sub-femtosecond temporal resolution.« less

Ultrafast carrier thermalization and trapping in silicon-germanium alloy probed by extreme ultraviolet transient absorption spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zürch, Michael; Chang, Hung-Tzu; Kraus, Peter M.

Semiconductor alloys containing silicon and germanium are of growing importance for compact and highly efficient photonic devices due to their favorable properties for direct integration into silicon platforms and wide tunability of optical parameters. Here, we report the simultaneous direct and energy-resolved probing of ultrafast electron and hole dynamics in a silicon-germanium alloy with the stoichiometry Si 0.25Ge 0.75 by extreme ultraviolet transient absorption spectroscopy. Probing the photoinduced dynamics of charge carriers at the germanium M 4,5-edge (~30 eV) allows the germanium atoms to be used as reporter atoms for carrier dynamics in the alloy. The photoexcitation of electrons acrossmore » the direct and indirect band gap into conduction band (CB) valleys and their subsequent hot carrier relaxation are observed and compared to pure germanium, where the Ge direct (ΔE gap,Ge,direct = 0.8 eV) and Si 0.25Ge 0.75 indirect gaps (ΔE gap,Si0.25Ge0.75,indirect = 0.95 eV) are comparable in energy. In the alloy, comparable carrier lifetimes are observed for the X, L, and Γ valleys in the conduction band. A midgap feature associated with electrons accumulating in trap states near the CB edge following intraband thermalization is observed in the Si 0.25Ge 0.75 alloy. The successful implementation of the reporter atom concept for capturing the dynamics of the electronic bands by site-specific probing in solids opens a route to study carrier dynamics in more complex materials with femtosecond and sub-femtosecond temporal resolution.« less

The total switch time of silicon bipolar transistors with base doping gradients or with germanium gradients in the base

NASA Astrophysics Data System (ADS)

Karlsteen, M.; Willander, M.

1993-11-01

In this paper the total switch time for a transistor in a Direct Coupled Transistor Logic (DCTL) circuit is simulated by using Laplace transformations of the Ebers-Moll equations. The influence of doping gradients and germanium gradients in the base is investigated and their relative importance and their limitations are established. In a well designed bipolar transistor only a minor enhancement of the total switch time is obtained with the use of a doping gradient in the base. However, for bipolar transistors with base thickness over 500 Å, an improperly selected doping profile could be devastating for the total switch time. For a bipolar transistor the improvement of the total switch time due to a linear germanium gradient in the base could be up to about 30% compared with an ordinary silicon bipolar transistor. Still, a too high germanium gradient forces the normal transistor current gain (α N) to grow and the total switch time is thereby increased. Further enhancement could be achieved by the use of a second degree polynomial germanium profile in the base. Also in this case, care must be taken not to enlarge the germanium gradient too much as the total switch time then starts to increase. In all cases the betterment of the base transit time that is introduced by the electric field will not be directly used to reduce the base transit time. Instead the improvement is mostly used to lower the emitter transition charging time. However, the most important parameter to control is the normal transistor current gain (α N) that has to be kept within a narrow range to keep the total switch time low.

Evaluating a 3-D transport model of atmospheric CO2 using ground-based, aircraft, and space-borne data

NASA Astrophysics Data System (ADS)

Feng, L.; Palmer, P. I.; Yang, Y.; Yantosca, R. M.; Kawa, S. R.; Paris, J.-D.; Matsueda, H.; Machida, T.

2010-07-01

We evaluate the GEOS-Chem atmospheric transport model (v8-02-01) of CO2 over 2003-2006, driven by GEOS-4 and GEOS-5 meteorology from the NASA Goddard Global Modelling and Assimilation Office, using surface, aircraft and space-borne concentration measurements of CO2. We use an established ensemble Kalman filter to estimate a posteriori biospheric+biomass burning (BS+BB) and oceanic (OC) CO2 fluxes from 22 geographical regions, following the TransCom 3 protocol, using boundary layer CO2 data from a subset of GLOBALVIEW surface sites. Global annual net BS+BB+OC CO2 fluxes over 2004-2006 for GEOS-4 (GEOS-5) meteorology are -4.4±0.9 (-4.2±0.9), -3.9±0.9 (-4.5±0.9), and -5.2±0.9 (-4.9±0.9) Pg C yr-1 , respectively. The regional a posteriori fluxes are broadly consistent in the sign and magnitude of the TransCom-3 study for 1992-1996, but we find larger net sinks over northern and southern continents. We find large departures from our a priori over Europe during summer 2003, over temperate Eurasia during 2004, and over North America during 2005, reflecting an incomplete description of terrestrial carbon dynamics. We find GEOS-4 (GEOS-5) a posteriori CO2 concentrations reproduce the observed surface trend of 1.91-2.43 ppm yr-1, depending on latitude, within 0.15 ppm yr-1 (0.2 ppm yr-1) and the seasonal cycle within 0.2 ppm (0.2 ppm) at all latitudes. We find the a posteriori model reproduces the aircraft vertical profile measurements of CO2 over North America and Siberia generally within 1.5 ppm in the free and upper troposphere but can be biased by up to 4-5 ppm in the boundary layer at the start and end of the growing season. The model has a small negative bias in the free troposphere CO2 trend (1.95-2.19 ppm yr-1) compared to AIRS data which has a trend of 2.21-2.63 ppm yr-1 during 2004-2006, consistent with surface data. Model CO2 concentrations in the upper troposphere, evaluated using CONTRAIL (Comprehensive Observation Network for TRace gases by AIrLiner) aircraft measurements, reproduce the magnitude and phase of the seasonal cycle of CO2 in both hemispheres. We generally find that the GEOS meteorology reproduces much of the observed tropospheric CO2 variability, suggesting that these meteorological fields will help make significant progress in understanding carbon fluxes as more data become available.

Search of low-mass WIMPs with a p -type point contact germanium detector in the CDEX-1 experiment

NASA Astrophysics Data System (ADS)

Zhao, W.; Yue, Q.; Kang, K. J.; Cheng, J. P.; Li, Y. J.; Wong, H. T.; Lin, S. T.; Chang, J. P.; Chen, J. H.; Chen, Q. H.; Chen, Y. H.; Deng, Z.; Du, Q.; Gong, H.; Hao, X. Q.; He, H. J.; He, Q. J.; Huang, H. X.; Huang, T. R.; Jiang, H.; Li, H. B.; Li, J.; Li, J.; Li, J. M.; Li, X.; Li, X. Y.; Li, Y. L.; Lin, F. K.; Liu, S. K.; Lü, L. C.; Ma, H.; Ma, J. L.; Mao, S. J.; Qin, J. Q.; Ren, J.; Ren, J.; Ruan, X. C.; Sharma, V.; Shen, M. B.; Singh, L.; Singh, M. K.; Soma, A. K.; Su, J.; Tang, C. J.; Wang, J. M.; Wang, L.; Wang, Q.; Wu, S. Y.; Wu, Y. C.; Xianyu, Z. Z.; Xiao, R. Q.; Xing, H. Y.; Xu, F. Z.; Xu, Y.; Xu, X. J.; Xue, T.; Yang, L. T.; Yang, S. W.; Yi, N.; Yu, C. X.; Yu, H.; Yu, X. Z.; Zeng, M.; Zeng, X. H.; Zeng, Z.; Zhang, L.; Zhang, Y. H.; Zhao, M. G.; Zhou, Z. Y.; Zhu, J. J.; Zhu, W. B.; Zhu, X. Z.; Zhu, Z. H.; CDEX Collaboration

2016-05-01

The CDEX-1 experiment conducted a search of low-mass (<10 GeV /c2 ) weakly interacting massive particles dark matter at the China Jinping Underground Laboratory using a p-type point-contact germanium detector with a fiducial mass of 915 g at a physics analysis threshold of 475 eVee. We report the hardware setup, detector characterization, data acquisition, and analysis procedures of this experiment. No excess of unidentified events is observed after the subtraction of the known background. Using 335.6 kg-days of data, exclusion constraints on the weakly interacting massive particle-nucleon spin-independent and spin-dependent couplings are derived.

Structural and optical properties of axial silicon-germanium nanowire heterojunctions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, X.; Tsybeskov, L., E-mail: tsybesko@njit.edu; Kamins, T. I.

2015-12-21

Detailed studies of the structural and optical properties of axial silicon-germanium nanowire heterojunctions show that despite the 4.2% lattice mismatch between Si and Ge they can be grown without a significant density of structural defects. The lattice mismatch induced strain is partially relieved due to spontaneous SiGe intermixing at the heterointerface during growth and lateral expansion of the Ge segment of the nanowire. The mismatch in Ge and Si coefficients of thermal expansion and low thermal conductivity of Si/Ge nanowire heterojunctions are proposed to be responsible for the thermally induced stress detected under intense laser radiation in photoluminescence and Ramanmore » scattering measurements.« less

Acoustic phonon dispersion at hypersonic frequencies in Si and Ge

NASA Astrophysics Data System (ADS)

Kuok, M. H.; Ng, S. C.; Rang, Z. L.; Lockwood, D. J.

2000-11-01

Brillouin spectra of the longitudinal acoustic (LA) mode, traveling along the [001] direction, in silicon and germanium have been recorded in 180° backscattering using 457.9-514.5-nm laser lines. The wave velocity of the LA phonon propagating in the [001] direction was determined at hypersonic frequencies, from the measured acoustic phonon dispersion in silicon and germanium. The elastic modulus c11 of the two semiconductors has been calculated from the respective measured hypersonic wave velocities and the results are compared with values determined from lower-frequency ultrasonic and other measurements. Interestingly, the hypersonic velocities are consistently lower by ~1-2 % than the ultrasonic ones, but they generally agree within the present experimental accuracy.

High-Resolution Gamma-Ray Imaging Measurements Using Externally Segmented Germanium Detectors

NASA Technical Reports Server (NTRS)

Callas, J.; Mahoney, W.; Skelton, R.; Varnell, L.; Wheaton, W.

1994-01-01

Fully two-dimensional gamma-ray imaging with simultaneous high-resolution spectroscopy has been demonstrated using an externally segmented germanium sensor. The system employs a single high-purity coaxial detector with its outer electrode segmented into 5 distinct charge collection regions and a lead coded aperture with a uniformly redundant array (URA) pattern. A series of one-dimensional responses was collected around 511 keV while the system was rotated in steps through 180 degrees. A non-negative, linear least-squares algorithm was then employed to reconstruct a 2-dimensional image. Corrections for multiple scattering in the detector, and the finite distance of source and detector are made in the reconstruction process.

Detached Bridgman Growth of Germanium and Germanium-Silicon Alloy Crystals

NASA Technical Reports Server (NTRS)

Szofran, F. R.; Volz, M. P.; Schweizer, M.; Cobb, S. D.; Motakef, S.; Croell, A.; Dold, P.; Curreri, Peter A. (Technical Monitor)

2002-01-01

Earth based experiments on the science of detached crystal growth are being conducted on germanium and germanium-silicon alloys (2 at% Si average composition) in preparation for a series of experiments aboard the International Space Station (ISS). The purpose of the microgravity experiments includes differentiating among proposed mechanisms contributing to detachment, and confirming or refining our understanding of the detachment mechanism. Because large contact angle are critical to detachment, sessile drop measurements were used to determine the contact angles as a function of temperature and composition for a large number of substrates made of potential ampoule materials. Growth experiments have used pyrolytic boron nitride (pBN) and fused silica ampoules with the majority of the detached results occurring predictably in the pBN. The contact angles were 173 deg (Ge) and 165 deg (GeSi) for pBN. For fused silica, the contact angle decreases from 150 deg to an equilibrium value of 117 deg (Ge) or from 129 deg to an equilibrium value of 100 deg (GeSi) over the duration of the experiment. The nature and extent of detachment is determined by using profilometry in conjunction with optical and electron microscopy. The stability of detachment has been analyzed, and an empirical model for the conditions necessary to achieve sufficient stability to maintain detached growth for extended periods has been developed. Results in this presentation will show that we have established the effects on detachment of ampoule material, pressure difference above and below the melt, and silicon concentration; samples that are nearly completely detached can be grown repeatedly in pBN.

Establishing a National 3d Geo-Data Model for Building Data Compliant to Citygml: Case of Turkey

NASA Astrophysics Data System (ADS)

Ates Aydar, S.; Stoter, J.; Ledoux, H.; Demir Ozbek, E.; Yomralioglu, T.

2016-06-01

This paper presents the generation of the 3D national building geo-data model of Turkey, which is compatible with the international OGC CityGML Encoding Standard. We prepare an ADE named CityGML-TRKBIS.BI that is produced by extending existing thematic modules of CityGML according to TRKBIS needs. All thematic data groups in TRKBIS geo-data model have been remodelled in order to generate the national large scale 3D geo-data model for Turkey. Specific attention has been paid to data groups that have different class structure according to related CityGML data themes such as building data model. Current 2D geo-information model for building data theme of Turkey (TRKBIS.BI) was established based on INSPIRE specifications for building (Core 2D and Extended 2D profiles), ISO/TC 211 standards and OGC web services. New version of TRKBIS.BI which is established according to semantic and geometric rules of CityGML will represent 2D-2.5D and 3D objects. After a short overview on generic approach, this paper describes extending CityGML building data theme according to TRKBIS.BI through several steps. First, building models of both standards were compared according to their data structure, classes and attributes. Second, CityGML building model was extended with respect to TRKBIS needs and CityGML-TRKBIS Building ADE was established in UML. This study provides new insights into 3D applications in Turkey. The generated 3D geo-data model for building thematic class will be used as a common exchange format that meets 2D, 2.5D and 3D implementation needs at national level.

Effect of the microstructure on electrical properties of high-purity germanium

NASA Astrophysics Data System (ADS)

Podkopaev, O. I.; Shimanskii, A. F.; Molotkovskaya, N. O.; Kulakovskaya, T. V.

2013-05-01

The interrelation between the electrical properties and the microstructure of high-purity germanium crystals has been revealed. The electrical conductivity of polycrystalline samples increases and the life-time of nonequilibrium charge carriers in them decreases with a decrease in the crystallite sizes.

Production, characterization and operation of Ge enriched BEGe detectors in GERDA

NASA Astrophysics Data System (ADS)

Agostini, M.; Allardt, M.; Andreotti, E.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Barros, N.; Baudis, L.; Bauer, C.; Becerici-Schmidt, N.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Benato, G.; Bettini, A.; Bezrukov, L.; Bode, T.; Borowicz, D.; Brudanin, V.; Brugnera, R.; Budjáš, D.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; D'Andrea, V.; Demidova, E. V.; Domula, A.; Egorov, V.; Falkenstein, R.; Freund, K.; Frodyma, N.; Gangapshev, A.; Garfagnini, A.; Gotti, C.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hegai, A.; Heisel, M.; Hemmer, S.; Heusser, G.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Ioannucci, L.; Janicskó Csáthy, J.; Jochum, J.; Junker, M.; Kazalov, V.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Klimenko, A.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lebedev, V. I.; Lehnert, B.; Liao, H. Y.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Misiaszek, M.; Nemchenok, I.; Nisi, S.; O'Shaughnessy, C.; Palioselitis, D.; Pandola, L.; Pelczar, K.; Pessina, G.; Pullia, A.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salathe, M.; Schmitt, C.; Schreiner, J.; Schulz, O.; Schütz, A.-K.; Schwingenheuer, B.; Schönert, S.; Shevchik, E.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Strecker, H.; Ur, C. A.; Vanhoefer, L.; Vasenko, A. A.; von Sturm, K.; Wagner, V.; Walter, M.; Wegmann, A.; Wester, T.; Wilsenach, H.; Wojcik, M.; Yanovich, E.; Zavarise, P.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zuber, K.; Zuzel, G.

2015-02-01

The GERmanium Detector Array ( Gerda) at the Gran Sasso Underground Laboratory (LNGS) searches for the neutrinoless double beta decay () of Ge. Germanium detectors made of material with an enriched Ge fraction act simultaneously as sources and detectors for this decay. During Phase I of theexperiment mainly refurbished semi-coaxial Ge detectors from former experiments were used. For the upcoming Phase II, 30 new Ge enriched detectors of broad energy germanium (BEGe)-type were produced. A subgroup of these detectors has already been deployed in Gerda during Phase I. The present paper reviews the complete production chain of these BEGe detectors including isotopic enrichment, purification, crystal growth and diode production. The efforts in optimizing the mass yield and in minimizing the exposure of the Ge enriched germanium to cosmic radiation during processing are described. Furthermore, characterization measurements in vacuum cryostats of the first subgroup of seven BEGe detectors and their long-term behavior in liquid argon are discussed. The detector performance fulfills the requirements needed for the physics goals of Gerda Phase II.

Dosimetric properties of germanium doped calcium borate glass subjected to 6 MV and 10 MV X-ray irradiations

NASA Astrophysics Data System (ADS)

Tengku Kamarul Bahri, T. N. H.; Wagiran, H.; Hussin, R.; Saeed, M. A.; Hossain, I.; Ali, H.

2014-10-01

Germanium doped calcium borate glasses are investigated in term of thermoluminescence properties to seek their possibility to use as glass radiation dosimeter. The samples were exposed to 6 MV, and 10 MV photon beams in a dose range of 0.5-4.0 Gy. There is a single and broad thermoluminescence glow curve that exhibits its maximum intensity at about 300 °C. Linear dose response behavior has been found in this dose range for the both photon energies. Effective atomic number, TL sensitivity, and reproducibility have also been studied. It is found that the sensitivity of germanium doped sample at 6 MV is only 1.28% and it is superior to the sensitivity at 10 MV. The reproducibility of germanium doped sample is good with a percentage of relative error less than 10%. The results indicate that this glass has a potential to be used as a radiation dosimetry, especially for application in radiotherapy.

Determination of the Wetting Angle of Germanium and Germanium-Silicon Melts on Different Substrate Materials

NASA Technical Reports Server (NTRS)

Kaiser, Natalie; Croell, Arne; Szofran, F. R.; Cobb. S. D.; Dold, P.; Benz, K. W.

1999-01-01

During Bridgman growth of semiconductors detachment of the crystal and the melt meniscus has occasionally been observed, mainly under microgravity (microg) conditions. An important factor for detached growth is the wetting angle of the melt with the crucible material. High contact angles are more likely to result in detachment of the growing crystal from the ampoule wall. In order to achieve detached growth of germanium (Ge) and germanium-silicon (GeSi) crystals under 1g and microg conditions, sessile drop measurements were performed to determine the most suitable ampoule material as well as temperature dependence of the surface tension for GeSi. Sapphire, fused quartz, glassy carbon, graphite, SiC, pyrolytic Boron Nitride (pBN), AIN, and diamond were used as substrates. Furthermore, different cleaning procedures and surface treatments (etching, sandblasting, etc.) of the same substrate material and their effect on the wetting behavior were studied during these experiments. pBN and AIN substrates exhibited the highest contact angles with values around 170 deg.

Method of Fabricating Schottky Barrier solar cell

NASA Technical Reports Server (NTRS)

Stirn, R. J.; Yeh, Y. C. M. (Inventor)

1982-01-01

On a thin substrate of low cost material with at least the top surface of the substrate being electrically conductive is deposited a thin layer of heavily doped n-type polycrystalline germanium, with crystalline sizes in the submicron range. A passivation layer may be deposited on the substrate to prevent migration of impurities into the polycrystalline germanium. The polycrystalline germanium is recrystallized to increase the crystal sizes in the germanium layer to not less than 5 micros to serve as a base layer on which a thin layer of gallium arsenide is vapor epitaxially grown to a selected thickness. A thermally-grown oxide layer of a thickness of several tens of angstroms is formed on the gallium arsenide layer. A metal layer, of not more about 100 angstroms thick, is deposited on the oxide layer, and a grid electrode is deposited to be in electrical contact with the top surface of the metal layer. An antireflection coating may be deposited on the exposed top surface of the metal layer.

Arene-Inserted Extended Germa[n]pericyclynes: Synthesis, Structure, and Phosphorescence Properties.

PubMed

Tanimoto, Hiroki; Mori, Junta; Ito, Shunichiro; Nishiyama, Yasuhiro; Morimoto, Tsumoru; Tanaka, Kazuo; Chujo, Yoshiki; Kakiuchi, Kiyomi

2017-07-26

This report describes the synthesis and characterization of arene-inserted extended (ArEx) germa[n]pericyclynes composed of germanium and 1,4-diethynylbenzene units. These novel cyclic germanium-π unit materials were synthesized with diethynylbenzene and germanium dichloride. X-ray crystallographic analysis revealed their structures, and the planar conformation of ArEx germa[4]pericyclyne along with the regular aromatic rings. UV/Vis absorption spectra and fluorescence emission spectra showed considerably unique and highly improved character compared to previously reported germa[n]pericyclynes. Even in the absence of transition metal components, phosphorescence emissions were observed, and the emission lifetimes were dramatically improved. ArEx germa[n]pericyclynes showed high photoluminescence quantum yields, whereas low photoluminescence quantum yields were observed for acyclic compounds. Density functional theory calculations show delocalized orbitals between skipped alkyne units through a germanium tether, and an increase in the HOMO energy level, leading to a small HOMO-LUMO energy gap. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gallium arsenide single crystal solar cell structure and method of making

NASA Technical Reports Server (NTRS)

Stirn, Richard J. (Inventor)

1983-01-01

A production method and structure for a thin-film GaAs crystal for a solar cell on a single-crystal silicon substrate (10) comprising the steps of growing a single-crystal interlayer (12) of material having a closer match in lattice and thermal expansion with single-crystal GaAs than the single-crystal silicon of the substrate, and epitaxially growing a single-crystal film (14) on the interlayer. The material of the interlayer may be germanium or graded germanium-silicon alloy, with low germanium content at the silicon substrate interface, and high germanium content at the upper surface. The surface of the interface layer (12) is annealed for recrystallization by a pulsed beam of energy (laser or electron) prior to growing the interlayer. The solar cell structure may be grown as a single-crystal n.sup.+ /p shallow homojunction film or as a p/n or n/p junction film. A Ga(Al)AS heteroface film may be grown over the GaAs film.

The MAJORANA DEMONSTRATOR: A search for neutrinoless double-beta decay of germanium-76

NASA Astrophysics Data System (ADS)

Schubert, Alexis; Majorana Collaboration

2011-04-01

Observation of neutrinoless double-beta decay (0 νββ) could determine whether the neutrino is a Majorana particle and may provide information on neutrino mass. The MAJORANA Collaboration will search for 0 νββ of 76Ge in an array of germanium detectors enriched to 86% in 76Ge. Germanium detectors are a well-understood technology and have the benefits of excellent energy resolution, a high Q-value, and the ability to act as source and detector. The p-type point contact germanium detectors chosen by the MAJORANA Collaboration provide low noise, low energy threshold, and some ability to distinguish between the signal and background events. MAJORANA is constructing the DEMONSTRATOR, which will be used to conduct research and development toward a tonne-scale Ge experiment. The DEMONSTRATOR will be installed deep underground and will contain 40 kg of Ge deployed in an ultra-low-background shielded environment. Research supported by DOE under contracts DE-AC05-00OR22725 and DE-FG02-97ER41020.

Errors and improvements in the use of archived meteorological data for chemical transport modeling: an analysis using GEOS-Chem v11-01 driven by GEOS-5 meteorology

NASA Astrophysics Data System (ADS)

Yu, Karen; Keller, Christoph A.; Jacob, Daniel J.; Molod, Andrea M.; Eastham, Sebastian D.; Long, Michael S.

2018-01-01

Global simulations of atmospheric chemistry are commonly conducted with off-line chemical transport models (CTMs) driven by archived meteorological data from general circulation models (GCMs). The off-line approach has the advantages of simplicity and expediency, but it incurs errors due to temporal averaging in the meteorological archive and the inability to reproduce the GCM transport algorithms exactly. The CTM simulation is also often conducted at coarser grid resolution than the parent GCM. Here we investigate this cascade of CTM errors by using 222Rn-210Pb-7Be chemical tracer simulations off-line in the GEOS-Chem CTM at rectilinear 0.25° × 0.3125° (≈ 25 km) and 2° × 2.5° (≈ 200 km) resolutions and online in the parent GEOS-5 GCM at cubed-sphere c360 (≈ 25 km) and c48 (≈ 200 km) horizontal resolutions. The c360 GEOS-5 GCM meteorological archive, updated every 3 h and remapped to 0.25° × 0.3125°, is the standard operational product generated by the NASA Global Modeling and Assimilation Office (GMAO) and used as input by GEOS-Chem. We find that the GEOS-Chem 222Rn simulation at native 0.25° × 0.3125° resolution is affected by vertical transport errors of up to 20 % relative to the GEOS-5 c360 online simulation, in part due to loss of transient organized vertical motions in the GCM (resolved convection) that are temporally averaged out in the 3 h meteorological archive. There is also significant error caused by operational remapping of the meteorological archive from a cubed-sphere to a rectilinear grid. Decreasing the GEOS-Chem resolution from 0.25° × 0.3125° to 2° × 2.5° induces further weakening of vertical transport as transient vertical motions are averaged out spatially and temporally. The resulting 222Rn concentrations simulated by the coarse-resolution GEOS-Chem are overestimated by up to 40 % in surface air relative to the online c360 simulations and underestimated by up to 40 % in the upper troposphere, while the tropospheric lifetimes of 210Pb and 7Be against aerosol deposition are affected by 5-10 %. The lost vertical transport in the coarse-resolution GEOS-Chem simulation can be partly restored by recomputing the convective mass fluxes at the appropriate resolution to replace the archived convective mass fluxes and by correcting for bias in the spatial averaging of boundary layer mixing depths.

Ultrahigh-pressure polyamorphism in GeO2 glass with coordination number >6

NASA Astrophysics Data System (ADS)

Kono, Yoshio; Kenney-Benson, Curtis; Ikuta, Daijo; Shibazaki, Yuki; Wang, Yanbin; Shen, Guoyin

2016-03-01

Knowledge of pressure-induced structural changes in glasses is important in various scientific fields as well as in engineering and industry. However, polyamorphism in glasses under high pressure remains poorly understood because of experimental challenges. Here we report new experimental findings of ultrahigh-pressure polyamorphism in GeO2 glass, investigated using a newly developed double-stage large-volume cell. The Ge-O coordination number (CN) is found to remain constant at ∼6 between 22.6 and 37.9 GPa. At higher pressures, CN begins to increase rapidly and reaches 7.4 at 91.7 GPa. This transformation begins when the oxygen-packing fraction in GeO2 glass is close to the maximal dense-packing state (the Kepler conjecture = ∼0.74), which provides new insights into structural changes in network-forming glasses and liquids with CN higher than 6 at ultrahigh-pressure conditions.

Geostationary Coastal and Air Pollution Events (GeoCAPE) Wide Angle Spectrometer (WAS)

NASA Technical Reports Server (NTRS)

Kotecki, Carl; Chu, Martha; Mannino, Antonio; Marx, Catherine Trout; Bowers, Gregory A.; Bolognese, Jeffrey A.; Matson, Elizabeth A.; McBirney, Thomas R.; Earle, Cleland P.; Choi, Michael K.;

Low temperature solution synthesis of silicon, germanium and Si-Ge axial heterostructures in nanorod and nanowire form.

PubMed

Flynn, G; Stokes, K; Ryan, K M

2018-05-31

Herein, we report the formation of silicon, germanium and more complex Si-SixGe1-x and Si-Ge axial 1D heterostructures, at low temperatures in solution. These nanorods/nanowires are grown using phenylated compounds of silicon and germanium as reagents, with precursor decomposition achieved at substantially reduced temperatures (200 °C for single crystal nanostructures and 300 °C for heterostructures), through the addition of a reducing agent. This low energy route for the production of these functional nanostructures as a wet chemical in high yield is attractive to meet the processing needs for next generation photovoltaics, batteries and electronics.

Ultrafast All-Optical Switching of Germanium-Based Flexible Metaphotonic Devices.

PubMed

Lim, Wen Xiang; Manjappa, Manukumara; Srivastava, Yogesh Kumar; Cong, Longqing; Kumar, Abhishek; MacDonald, Kevin F; Singh, Ranjan

2018-03-01

Incorporating semiconductors as active media into metamaterials offers opportunities for a wide range of dynamically switchable/tunable, technologically relevant optical functionalities enabled by strong, resonant light-matter interactions within the semiconductor. Here, a germanium-thin-film-based flexible metaphotonic device for ultrafast optical switching of terahertz radiation is experimentally demonstrated. A resonant transmission modulation depth of 90% is achieved, with an ultrafast full recovery time of 17 ps. An observed sub-picosecond decay constant of 670 fs is attributed to the presence of trap-assisted recombination sites in the thermally evaporated germanium film. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interfacial Properties of Germanium Nitride Dielectric Layers on Germanium.

DTIC Science & Technology

1986-09-30

choice or a process for growing Ge N , layers on germa - nium. a number of workers have employed various de. mum. posited layers on germanium. While...N00014-84-K-0459 V6 Office of Naval Research (Mr. Max N . Yoder, Electronic Division) 4: 800 North Quincy Street Arlington, Virginia 22217 Interfacial...z4) 3 Co0 C14 CM- Lfl n X sj E 𔃺 01 N S) Li (m* m n1 Ln m CU OT X)-(, (L 0IX) D/13si E- 1 0n CtZ) 4-4C ~ IN I- I L L0tX Cd) JN N in - Growth of

Refractive index profiles of Ge-doped optical fibers with nanometer spatial resolution using atomic force microscopy.

PubMed

Pace, P; Huntington, Shane; Lyytikäinen, K; Roberts, A; Love, J

2004-04-05

We show a quantitative connection between Refractive Index Profiles (RIP) and measurements made by an Atomic Force Microscope (AFM). Germanium doped fibers were chemically etched in hydrofluoric acid solution (HF) and the wet etching characteristics of germanium were studied using an AFM. The AFM profiles were compared to both a concentration profile of the preform determined using a Scanning Electron Microscope (SEM) and a RIP of the fiber measured using a commercial profiling instrument, and were found to be in excellent agreement. It is now possible to calculate the RIP of a germanium doped fiber directly from an AFM profile.

Mapping the electromagnetic field confinement in the gap of germanium nanoantennas with plasma wavelength of 4.5 micrometers

NASA Astrophysics Data System (ADS)

Calandrini, Eugenio; Venanzi, Tommaso; Appugliese, Felice; Badioli, Michela; Giliberti, Valeria; Baldassarre, Leonetta; Biagioni, Paolo; De Angelis, Francesco; Klesse, Wolfgang M.; Scappucci, Giordano; Ortolani, Michele

2016-09-01

We study plasmonic nanoantennas for molecular sensing in the mid-infrared made of heavily doped germanium, epitaxially grown with a bottom-up doping process and featuring free carrier density in excess of 1020 cm-3. The dielectric function of the 250 nm thick germanium film is determined, and bow-tie antennas are designed, fabricated, and embedded in a polymer. By using a near-field photoexpansion mapping technique at λ = 5.8 μm, we demonstrate the existence in the antenna gap of an electromagnetic energy density hotspot of diameter below 100 nm and confinement volume 105 times smaller than λ3.

Technical, analytical and computer support

NASA Technical Reports Server (NTRS)

1972-01-01

The development of a rigorous mathematical model for the design and performance analysis of cylindrical silicon-germanium thermoelectric generators is reported that consists of two parts, a steady-state (static) and a transient (dynamic) part. The material study task involves the definition and implementation of a material study that aims to experimentally characterize the long term behavior of the thermoelectric properties of silicon-germanium alloys as a function of temperature. Analytical and experimental efforts are aimed at the determination of the sublimation characteristics of silicon germanium alloys and the study of sublimation effects on RTG performance. Studies are also performed on a variety of specific topics on thermoelectric energy conversion.

The GeoEye Satellite Constellation

NASA Technical Reports Server (NTRS)

Dial, Gene; Cole, Aaron; Lutes, James; McKune, John; Martinez, Mike; Rao, R. S.; Taylor, Martin

2007-01-01

The GeoEye Constellation consists of: a) IKONOS and OrbView-3 for high resolution; b) GeoEye with higher resolution 1Q2007; c) RESOUCESAT-1 for global crop assessment; d) OrbView-2 for ocean research and fish. IKONOS performance in 2005 included stable image quality, radiometry and geometric accuracy. reliability is 80% to 2008. Demonstrated capacity for high-volume, quick-response collection and production.

A Study of Seventh Grade Geometry Posttest Scores after Using the GeoLeg Manipulative Tool

ERIC Educational Resources Information Center

Pacilli, Phyllis T.

2010-01-01

The purpose of this research was to identify if (1) there is a difference in student achievement between students who use the GeoLeg manipulative tool and students who use a traditional compass, protractor, and ruler on the same geometry unit; (2) there is a difference in student achievement between the genders between those who use the GeoLeg…

Germanium ``hexa'' detector: production and testing

NASA Astrophysics Data System (ADS)

Sarajlić, M.; Pennicard, D.; Smoljanin, S.; Hirsemann, H.; Struth, B.; Fritzsch, T.; Rothermund, M.; Zuvic, M.; Lampert, M. O.; Askar, M.; Graafsma, H.

2017-01-01

Here we present new result on the testing of a Germanium sensor for X-ray radiation. The system is made of 3 × 2 Medipix3RX chips, bump-bonded to a monolithic sensor, and is called ``hexa''. Its dimensions are 45 × 30 mm2 and the sensor thickness was 1.5 mm. The total number of the pixels is 393216 in the matrix 768 × 512 with pixel pitch 55 μ m. Medipix3RX read-out chip provides photon counting read-out with single photon sensitivity. The sensor is cooled to -126°C and noise levels together with flat field response are measured. For -200 V polarization bias, leakage current was 4.4 mA (3.2 μ A/mm2). Due to higher leakage around 2.5% of all pixels stay non-responsive. More than 99% of all pixels are bump bonded correctly. In this paper we present the experimental set-up, threshold equalization procedure, image acquisition and the technique for bump bond quality estimate.

Improved WIMP-search reach of the CDMS II germanium data

DOE PAGES

Agnese, R.

2015-10-12

CDMS II data from the five-tower runs at the Soudan Underground Laboratory were reprocessed with an improved charge-pulse fitting algorithm. Two new analysis techniques to reject surface-event backgrounds were applied to the 612 kg days germanium-detector weakly interacting massive particle (WIMP)-search exposure. An extended analysis was also completed by decreasing the 10 keV analysis threshold to ~5 keV, to increase sensitivity near a WIMP mass of 8 GeV/c 2. After unblinding, there were zero candidate events above a deposited energy of 10 keV and six events in the lower-threshold analysis. This yielded minimum WIMP-nucleon spin-independent scattering cross-section limits of 1.8×10more » –44 and 1.18×10 –41 at 90% confidence for 60 and 8.6 GeV/c 2 WIMPs, respectively. This improves the previous CDMS II result by a factor of 2.4 (2.7) for 60 (8.6) GeV/c 2 WIMPs.« less

Improved WIMP-search reach of the CDMS II germanium data

DOE PAGES

Agnese, R.

2015-10-12

CDMS II data from the five-tower runs at the Soudan Underground Laboratory were reprocessed with an improved charge-pulse fitting algorithm. Two new analysis techniques to reject surface-event backgrounds were applied to the 612 kg days germanium-detector weakly interacting massive particle (WIMP)-search exposure. An extended analysis was also completed by decreasing the 10 keV analysis threshold to ~5 keV, to increase sensitivity near a WIMP mass of 8 GeV/c 2. After unblinding, there were zero candidate events above a deposited energy of 10 keV and six events in the lower-threshold analysis. This yielded minimum WIMP-nucleon spin-independent scattering cross-section limits of 1.8×10more » –44 and 1.18×10 –41 at 90% confidence for 60 and 8.6 GeV/c 2 WIMPs, respectively. Furthermore, this improves the previous CDMS II result by a factor of 2.4 (2.7) for 60 (8.6) GeV/c 2 WIMPs.« less

Segmentation and pulse shape discrimination techniques for rejecting background in germanium detectors

NASA Technical Reports Server (NTRS)

Roth, J.; Primbsch, J. H.; Lin, R. P.

1984-01-01

The possibility of rejecting the internal beta-decay background in coaxial germanium detectors by distinguishing between the multi-site energy losses characteristic of photons and the single-site energy losses of electrons in the range 0.2 - 2 MeV is examined. The photon transport was modeled with a Monte Carlo routine. Background rejection by both multiple segmentation and pulse shape discrimination techniques is investigated. The efficiency of a six 1 cm-thick segment coaxial detector operating in coincidence mode alone is compared to that of a two-segment (1 cm and 5 cm) detector employing both front-rear coincidence and PSD in the rear segment to isolate photon events. Both techniques can provide at least 95 percent rejection of single-site events while accepting at least 80 percent of the multi-site events above 500 keV.

Multifunctional ligand for use as a diagnostic or therapeutic pharmaceutical

DOEpatents

Katti, Kattesh V.; Volkert, Wynn A.; Ketring, Alan R.; Singh, Prahlad R.

1996-01-01

A compound and method of making a compound for use as a diagnostic or therapeutic pharmaceutical comprises either a phosphorous or germanium core and at least two hydrazine groups forming a ligand for bonding to a metal extending from the phosphorous or germanium core.

Growth Behavior and Electronic Structure of Noble Metal-Doped Germanium Clusters.

PubMed

Mahtout, Sofiane; Siouani, Chaouki; Rabilloud, Franck

2018-01-18

Structures, energetics, and electronic properties of noble metal-doped germanium (MGe n with M = Cu, Ag, Au; n = 1-19) clusters are systematically investigated by using the density functional theory (DFT) approach. The endohedral structures in which the metal atom is encapsulated inside of a germanium cage appear at n = 10 when the dopant is Cu and n = 12 for M = Ag and Au. While Cu doping enhances the stability of the corresponding germanium frame, the binding energies of AgGe n and AuGe n are always lower than those of pure germanium clusters. Our results highlight the great stability of the CuGe 10 cluster in a D 4d structure and, to a lesser extent, that of AgGe 15 and AuGe 15 , which exhibits a hollow cage-like geometry. The sphere-type geometries obtained for n = 10-15 present a peculiar electronic structure in which the valence electrons of the noble metal and Ge atoms are delocalized and exhibit a shell structure associated with the quasi-spherical geometry. It is found that the coinage metal is able to give both s- and d-type electrons to be reorganized together with the valence electrons of Ge atoms through a pooling of electrons. The cluster size dependence of the stability, the frontier orbital energy gap, the vertical ionization potentials, and electron affinities are given.

Reduced graphene oxide-germanium quantum dot nanocomposite: electronic, optical and magnetic properties

NASA Astrophysics Data System (ADS)

Amollo, Tabitha A.; Mola, Genene T.; Nyamori, Vincent O.

2017-12-01

Graphene provides numerous possibilities for structural modification and functionalization of its carbon backbone. Localized magnetic moments can, as well, be induced in graphene by the formation of structural defects which include vacancies, edges, and adatoms. In this work, graphene was functionalized using germanium atoms, we report the effect of the Ge ad atoms on the structural, electrical, optical and magnetic properties of graphene. Reduced graphene oxide (rGO)-germanium quantum dot nanocomposites of high crystalline quality were synthesized by the microwave-assisted solvothermal reaction. Highly crystalline spherical shaped germanium quantum dots, of diameter ranging between 1.6-9.0 nm, are anchored on the basal planes of rGO. The nanocomposites exhibit high electrical conductivity with a sheet resistance of up to 16 Ω sq-1. The electrical conductivity is observed to increase with the increase in Ge content in the nanocomposites. High defect-induced magnetization is attained in the composites via germanium adatoms. The evolution of the magnetic moments in the nanocomposites and the coercivity showed marked dependence on the Ge quantum dots size and concentration. Quantum confinement effects is evidenced in the UV-vis absorbance spectra and photoluminescence emission spectra of the nanocomposites which show marked size-dependence. The composites manifest strong absorption in the UV region, strong luminescence in the near UV region, and a moderate luminescence in the visible region.

Application of CCD drift-scan photoelectric technique on monitoring GEO satellites

NASA Astrophysics Data System (ADS)

Yu, Yong; Zhao, Xiao-Fen; Luo, Hao; Mao, Yin-Dun; Tang, Zheng-Hong

2018-05-01

Geosynchronous Earth Orbit (GEO) satellites are widely used because of their unique characteristics of high-orbit and remaining permanently in the same area of the sky. Precise monitoring of GEO satellites can provide a key reference for the judgment of satellite operation status, the capture and identification of targets, and the analysis of collision warning. The observation using ground-based optical telescopes plays an important role in the field of monitoring GEO targets. Different from distant celestial bodies, there is a relative movement between the GEO target and the background reference stars, which makes the conventional observation method limited for long focal length telescopes. CCD drift-scan photoelectric technique is applied on monitoring GEO targets. In the case of parking the telescope, the good round images of the background reference stars and the GEO target at the same sky region can be obtained through the alternating observation of CCD drift-scan mode and CCD stare mode, so as to improve the precision of celestial positioning for the GEO target. Observation experiments of GEO targets were carried out with 1.56-meter telescope of Shanghai Astronomical Observatory. The results show that the application of CCD drift-scan photoelectric technique makes the precision of observing the GEO target reach the level of 0.2″, which gives full play to the advantage of the long focal length of the telescope. The effect of orbit improvement based on multi-pass of observations is obvious and the prediction precision of extrapolating to 72-h is in the order of several arc seconds in azimuth and elevation.

US GeoData

USGS Publications Warehouse

,

1992-01-01

US GeoData tapes are computer tapes which contain cartographic data in digital form. The 1:2,000,000-scale data are available in two forms. The graphic form can be used to generate computer-plotted maps. The content and scale of the maps can be varied to meet your needs. The topologically-structured form of US GeoData is suitable for input to geographic information systems for use in spatial analysis and geographic studies. Both forms must be used in conjunction with appropriate software. US GeoData tapes offer convenience, accuracy, flexibility, and cost effectiveness to many map users. Business, industry, and government users who are involved in network planning and analysis, transportation, demography, land use, or any activity where data can be related to, or plotted on a map will find US GeoData a valuable resource.

Ion beam modification of structural and optical properties of GeO2 thin films deposited at various substrate temperatures using pulsed laser deposition

NASA Astrophysics Data System (ADS)

Rathore, Mahendra Singh; Vinod, Arun; Angalakurthi, Rambabu; Pathak, A. P.; Singh, Fouran; Thatikonda, Santhosh Kumar; Nelamarri, Srinivasa Rao

2017-11-01

High energy heavy ion irradiation-induced modification of high quality crystalline GeO2 thin films grown at different substrate temperatures ranging from 100 to 500 °C using pulsed laser deposition has been investigated. The pristine films were irradiated with 100 MeV Ag7+ ions at fixed fluence of 1 × 1013 ions/cm2. These pristine and irradiated films have been characterized using X-ray diffraction, atomic force microscopy, Raman spectroscopy, Fourier transform infrared and photoluminescence spectroscopy. The XRD and Raman results of pristine films confirm the formation of hexagonal structure of GeO2 films, whereas the irradiation eliminates all the peaks except major GeO2 peak of (101) plane. It is evident from the XRD results that crystallite size changes with substrate temperature and SHI irradiation. The surface morphology of films was studied by AFM. The functional group of pristine and irradiated films was investigated by IR transmission spectra. Pristine films exhibited strong photoluminescence around 342 and 470 nm due to oxygen defects and a red shift in the PL bands is observed after irradiation. Possible mechanism of tuning structural and optical properties of pristine as well as irradiated GeO2 films with substrate temperature and ion beam irradiation has been reported in detail.

Germanium geochemistry and mineralogy

USGS Publications Warehouse

Bernstein, L.R.

1985-01-01

Germanium is enriched in the following geologic environments: 1. (1) iron meteorites and terrestrial iron-nickel; 2. (2) sulfide ore deposits, particularly those hosted by sedimentary rocks; 3. (3) iron oxide deposits; 4. (4) oxidized zones of Ge-bearing sulfide deposits; 5. (5) pegmatites, greisens, and skarns; and 6. (6) coal and lignitized wood. In silicate melts, Ge is highly siderophile in the presence of native iron-nickel; otherwise, it is highly lithophile. Among silicate minerals, Ge is concentrated in those having less polymerized silicate tetrahedra such as olivine and topaz. In deposits formed from hydrothermal solutions, Ge tends to be enriched mostly in either sulfides or in fluorine-bearing phases; it is thus concentrated both in some hydrothermal sulfide deposits and in pegmatites, greisens, and skarns. In sulfide deposits that formed from solutions having low to moderate sulfur activity, Ge is concentrated in sphalerite in amounts up to 3000 ppm. Sulfide deposits that formed from solutions having higher sulfur activity allowed Ge to either form its own sulfides, particularly with Cu, or to substitute for As, Sn, or other metals in sulfosalts. The Ge in hydrothermal fluids probably derives from enrichment during the fractional crystallization of igneous fluids, or is due to the incorporation of Ge from the country rocks, particularly from those containing organic material. Germanium bonds to lignin-derivative organic compounds that are found in peat and lignite, accounting for its common concentration in coals and related organic material. Germanium is precipitated from water together with iron hydroxide, accounting for its concentration in some sedimentary and supergene iron oxide deposits. It also is able to substitute for Fe in magnetite in a variety of geologic environments. In the oxidized zone of Ge-bearing sulfide deposits, Ge is concentrated in oxides, hydroxides, and hydroxy-sulfates, sometimes forming its own minerals. It is particularly enriched in some iron- and manganese-bearing oxides and hydroxides, including goethite (up to 5300 ppm) and hematite (up to 7000 ppm). ?? 1985.

Solar neutrinos as a signal and background in direct-detection experiments searching for sub-GeV dark matter with electron recoils

NASA Astrophysics Data System (ADS)

Essig, Rouven; Sholapurkar, Mukul; Yu, Tien-Tien

2018-05-01

Direct-detection experiments sensitive to low-energy electron recoils from sub-GeV dark matter interactions will also be sensitive to solar neutrinos via coherent neutrino-nucleus scattering (CNS), since the recoiling nucleus can produce a small ionization signal. Solar neutrinos constitute both an interesting signal in their own right and a potential background to a dark matter search that cannot be controlled or reduced by improved shielding, material purification and handling, or improved detector design. We explore these two possibilities in detail for semiconductor (silicon and germanium) and xenon targets, considering several possibilities for the unmeasured ionization efficiency at low energies. For dark-matter-electron-scattering searches, neutrinos start being an important background for exposures larger than ˜1 - 10 kg -years in silicon and germanium, and for exposures larger than ˜0.1 - 1 kg -year in xenon. For the absorption of bosonic dark matter (dark photons and axion-like particles) by electrons, neutrinos are most relevant for masses below ˜1 keV and again slightly more important in xenon. Treating the neutrinos as a signal, we find that the CNS of 8B neutrinos can be observed with ˜2 σ significance with exposures of ˜2 , 7, and 20 kg-years in xenon, germanium, and silicon, respectively, assuming there are no other backgrounds. We give an example for how this would constrain nonstandard neutrino interactions. Neutrino components at lower energy can only be detected if the ionization efficiency is sufficiently large. In this case, observing pep neutrinos via CNS requires exposures ≳10 - 100 kg -years in silicon or germanium (˜1000 kg -years in xenon), and observing CNO neutrinos would require an order of magnitude more exposure. Only silicon could potentially detect 7Be neutrinos. These measurements would allow for a direct measurement of the electron-neutrino survival probability over a wide energy range.

GeoSciML version 3: A GML application for geologic information

NASA Astrophysics Data System (ADS)

International Union of Geological Sciences., I. C.; Richard, S. M.

2011-12-01

After 2 years of testing and development, XML schema for GeoSciML version 3 are now ready for application deployment. GeoSciML draws from many geoscience data modelling efforts to establish a common suite of feature types to represent information associated with geologic maps (materials, structures, and geologic units) and observations including structure data, samples, and chemical analyses. After extensive testing and use case analysis, in December 2008 the CGI Interoperability Working Group (IWG) released GeoSciML 2.0 as an application schema for basic geological information. GeoSciML 2.0 is in use to deliver geologic data by the OneGeology Europe portal, the Geological Survey of Canada Groundwater Information Network (wet GIN), and the Auscope Mineral Resources portal. GeoSciML to version 3.0 is updated to OGC Geography Markup Language v3.2, re-engineered patterns for association of element values with controlled vocabulary concepts, incorporation of ISO19156 Observation and Measurement constructs for representing numeric and categorical values and for representing analytical data, incorporation of EarthResourceML to represent mineral occurrences and mines, incorporation of the GeoTime model to represent GSSP and stratigraphic time scale, and refactoring of the GeoSciML namespace to follow emerging ISO practices for decoupling of dependencies between standardized namespaces. These changes will make it easier for data providers to link to standard vocabulary and registry services. The depth and breadth of GeoSciML remains largely unchanged, covering the representation of geologic units, earth materials and geologic structures. ISO19156 elements and patterns are used to represent sampling features such as boreholes and rock samples, as well as geochemical and geochronologic measurements. Geologic structures include shear displacement structures (brittle faults and ductile shears), contacts, folds, foliations, lineations and structures with no preferred orientation (e.g. 'miarolitic cavities'). The Earth material package allows for the description of both individual components, such as minerals, and compound materials, such as rocks or unconsolidated materials. Provision is made for alteration, weathering, metamorphism, particle geometry, fabric, and petrophysical descriptions. Mapped features describe the shape of the geological features using standard GML geometries, such as polygons, lines, points or 3D volumes. Geological events provide the age, process and environment of formation of geological features. The Earth Resource section includes features to represent mineral occurrences and mines and associated human activities independently. This addition allows description of resources and reserves that can comply with national and internationally accepted reporting codes. GeoSciML v3 is under consideration as the data model for INSPIRE annex 2 geologic reporting in Europe.

Extreme ultraviolet probing of nonequilibrium dynamics in high energy density germanium

NASA Astrophysics Data System (ADS)

Principi, E.; Giangrisostomi, E.; Mincigrucci, R.; Beye, M.; Kurdi, G.; Cucini, R.; Gessini, A.; Bencivenga, F.; Masciovecchio, C.

2018-05-01

Intense femtosecond infrared laser pulses induce a nonequilibrium between thousands of Kelvin hot valence electrons and room-temperature ions in a germanium sample foil. The evolution of this exotic state of matter is monitored with time-resolved extreme ultraviolet absorption spectroscopy across the Ge M2 ,3 edge (≃30 eV ) using the FERMI free-electron laser. We analyze two distinct regimes in the ultrafast dynamics in laser-excited Ge: First, on a subpicosecond time scale, the electron energy distribution thermalizes to an extreme temperature unreachable in equilibrium solid germanium; then, during the following picoseconds, the lattice reacts strongly altering the electronic structure and resulting in melting to a metallic state alongside a breakdown of the local atomic order. Data analysis, based on a hybrid approach including both numerical and analytical calculations, provides an estimation of the electron and ion temperatures, the electron density of states, the carrier-phonon relaxation time, as well as the carrier density and lattice heat capacity under those extreme nonequilibrium conditions. Related structural anomalies, such as the occurrence of a transient low-density liquid phase and the possible drop in lattice heat capacity are discussed.

Neutrinoless double beta decay in Gerda

NASA Astrophysics Data System (ADS)

Grabmayr, Peter; Gerda Collaboration

2015-10-01

The Germanium Detector Array (Gerda) experiment searches for the neutrinoless double beta decay in 76Ge. This lepton number violating process is predicted by extensions of the standard model. Gerda follows a staged approach by increasing mass and lowering the background level from phase to phase. Gerda is setup at the Gran Sasso underground laboratory of INFN, Italy. An array of high-purity germanium detectors is lowered directly in liquid argon for shielding and cooling. Further background reduction is achieved by an instrumented water buffer. In Phase I an exposure of 21.6 kg yr was collected at a background level of 10-2 cts/(keV kg yr). The lower limit on the half-life of 76Ge > 2 . 1 .1025 yr (90% C.L.) has been published. Further analyses search for decay into excited states or the accompanied Majoron decay. Presently, Phase II is in preparation which intends to reach a background level of 10-3 cts/(keV kg yr) and to increase the exposure to 100 kg yr. About 20 kg of novel thick-window BEGe (Broad Energy Germanium) detectors will be added and the liquid argon will be instrumented. The status of Phase II preparation and results from the commissioning runs will be presented as well as some further results from Phase I.

LArGe: active background suppression using argon scintillation for the Gerda 0ν β β -experiment

NASA Astrophysics Data System (ADS)

Agostini, M.; Barnabé-Heider, M.; Budjáš, D.; Cattadori, C.; Gangapshev, A.; Gusev, K.; Heisel, M.; Junker, M.; Klimenko, A.; Lubashevskiy, A.; Pelczar, K.; Schönert, S.; Smolnikov, A.; Zuzel, G.

2015-10-01

LArGe is a Gerda low-background test facility to study novel background suppression methods in a low-background environment, for future application in the Gerda experiment. Similar to Gerda, LArGe operates bare germanium detectors submersed into liquid argon (1 m^3, 1.4 tons), which in addition is instrumented with photomultipliers to detect argon scintillation light. The scintillation signals are used in anti-coincidence with the germanium detectors to effectively suppress background events that deposit energy in the liquid argon. The background suppression efficiency was studied in combination with a pulse shape discrimination (PSD) technique using a BEGe detector for various sources, which represent characteristic backgrounds to Gerda. Suppression factors of a few times 10^3 have been achieved. First background data of LArGe with a coaxial HPGe detector (without PSD) yield a background index of (0.12-4.6)× 10^{-2} cts/(keV kg year) (90 % C.L.), which is at the level of Gerda Phase I. Furthermore, for the first time we monitor the natural ^{42}Ar abundance (parallel to Gerda), and have indication for the 2ν β β -decay in natural germanium. These results show the effectivity of an active liquid argon veto in an ultra-low background environment. As a consequence, the implementation of a liquid argon veto in Gerda Phase II is pursued.

Stable and selective self-assembly of α-lipoic acid on Ge(001) for biomolecule immobilization

NASA Astrophysics Data System (ADS)

Kazmierczak, M.; Flesch, J.; Mitzloff, J.; Capellini, G.; Klesse, W. M.; Skibitzki, O.; You, C.; Bettenhausen, M.; Witzigmann, B.; Piehler, J.; Schroeder, T.; Guha, S.

2018-05-01

We demonstrate a novel method for the stable and selective surface functionalization of germanium (Ge) embedded in silicon dioxide. The Ge(001) surface is functionalized using α-lipoic acid (ALA), which can potentially be utilized for the immobilization of a wide range of biomolecules. We present a detailed pH-dependence study to establish the effect of the incubation pH value on the adsorption layer of the ALA molecules. A threshold pH value for functionalization is identified, dividing the examined pH range into two regions. Below a pH value of 7, the formation of a disordered ALA multilayer is observed, whereas a stable well-ordered ALA mono- to bi-layer on Ge(001) is achieved at higher pH values. Furthermore, we analyze the stability of the ALA layer under ambient conditions, revealing the most stable functionalized Ge(001) surface to effectively resist oxidation for up to one week. Our established functionalization method paves the way towards the successful immobilization of biomolecules in future Ge-based biosensors.

Assessment of GeB doped SiO2 optical fiber for the application of remote radiation sensing system

NASA Astrophysics Data System (ADS)

Alawiah, A.; Fadhli, M. M.; Bauk, S.; Abdul-Rashid, H. A.; Maah, M. J.

2013-12-01

The research and development efforts on the silica (SiO2) optical fiber for application in radiation sensing and other dosimetry field have become quite active. The widely used LiF based dosimeter (TLD) has shown a relatively low reproducibility and there is a time delay in dose assessment which loses its capability as direct real-time dose assessment dosimeters unlike diodes. The macroscopic size of the optical fiber generally does not allow direct in vivo dose sensing in the inner organ for radiotherapy and medical imaging. A flat optical fiber (FF) with nominal dimensions of (0.08 x10 x 10) mm3 of pure silica SiO2 and GeO2 with Boron doped silica fiber SiO2 was selected for this research. The Germanium was used a dopant to enhance the flat optical fiber to reach much higher responsiveness and dose sensitivity in high energy and high dose irradiation. Together with this combination, both TLD dimension and dose assessment issues was hoped to be overcome. The research conducted by comparing the response of pure silica SiO2 flat optical fiber with a GeO2 with Boron doped silica SiO2 flat optical fiber. The FF sample was annealed at 400°C for one hour before irradiated. Kinetic parameters and dosimetric glow curve of TL response and sensitivity were studied with respect to the electron beam of high dose of micro beam irradiation of 1.0 kGy, 5.0 kGy, 10.0 kGy, 50.0 kGy, 100.0 kGy, 500.0 kGy, and 1.0 MGy using Singapore Synchrotron Light Source's (PCIT) beamline. The PCIT operates at 500mA current with real time current range from 90-100mA, dose rate of 3.03 MGy/hour and energy at 8.9KeV. The source to Source Surface Distance (SSD) was at 6.0 cm, with a field size of 20mm × 8mm diameter of a half circle. The TL response was measured using a TLD reader Harshaw Model 3500. The Time-Temperature-Profile (TTP) of the reader was obtained to a preheat temperature of 150 °C for 5 s, the output signal being acquired at a temperature ramprate of 35 °Cs-1, acquisition time of 10 s and a maximum temperature of 400 °C each of the FF samples. All reading was taken under N2 gas flow, suppressing oxidation and potential triboluminescence. The proposed FF shows the excellent TL response for high energy irradiation and good reproducibility and exhibits a very low rate of fading and low variation background signal. From these results, the proposed FF can be used as a radiation dosimeter in remote radiation sensing and favorably compares with the widely used of LiF based dosimeter on common medical radiotherapy application.

The Population of Optically Faint GEO Debris

NASA Technical Reports Server (NTRS)

Seitzer, Patrick; Barker, Ed; Buckalew, Brent; Burkhardt, Andrew; Cowardin, Heather; Frith, James; Gomez, Juan; Kaleida, Catherine; Lederer, Susan M.; Lee, Chris H.

2016-01-01

The 6.5-m Magellan telescope 'Walter Baade' at the Las Campanas Observatory in Chile has been used for spot surveys of the GEO orbital regime to study the population of optically faint GEO debris. The goal is to estimate the size of the population of GEO debris at sizes much smaller than can be studied with 1-meter class telescopes. Despite the small size of the field of view of the Magellan instrument (diameter 0.5-degree), a significant population of objects fainter than R = 19th magnitude have been found with angular rates consistent with circular orbits at GEO. We compare the size of this population with the numbers of GEO objects found at brighter magnitudes by smaller telescopes. The observed detections have a wide range in characteristics starting with those appearing as short uniform streaks. But there are a substantial number of detections with variations in brightness, flashers, during the 5-second exposure. The duration of each of these flashes can be extremely brief: sometimes less than half a second. This is characteristic of a rapidly tumbling object with a quite variable projected size times albedo. If the albedo is of the order of 0.2, then the largest projected size of these objects is around 10-cm. The data in this paper was collected over the last several years using Magellan's IMACS camera in f/2 mode. The analysis shows the brightness bins for the observed GEO population as well as the periodicity of the flashers. All objects presented are correlated with the catalog: the focus of the paper will be on the uncorrelated, optically faint, objects. The goal of this project is to better characterize the faint debris population in GEO that access to a 6.5-m optical telescope in a superb site can provide.

Active noise canceling system for mechanically cooled germanium radiation detectors

DOEpatents

Nelson, Karl Einar; Burks, Morgan T

2014-04-22

A microphonics noise cancellation system and method for improving the energy resolution for mechanically cooled high-purity Germanium (HPGe) detector systems. A classical adaptive noise canceling digital processing system using an adaptive predictor is used in an MCA to attenuate the microphonics noise source making the system more deployable.

40 CFR 421.183 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2010 CFR

2010-07-01

... and Secondary Germanium and Gallium Subcategory § 421.183 Effluent limitations guidelines representing... liquor. BAT Limitations for the Primary and Secondary Germanium and Gallium Subcategory Pollutant or... and Gallium Subcategory Pollutant or pollutant property Maximum for any 1 day Maximum for monthly...

40 CFR 421.183 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2012 CFR

2012-07-01

... and Secondary Germanium and Gallium Subcategory § 421.183 Effluent limitations guidelines representing... liquor. BAT Limitations for the Primary and Secondary Germanium and Gallium Subcategory Pollutant or... and Gallium Subcategory Pollutant or pollutant property Maximum for any 1 day Maximum for monthly...

40 CFR 421.183 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2013 CFR

2013-07-01

... and Secondary Germanium and Gallium Subcategory § 421.183 Effluent limitations guidelines representing... liquor. BAT Limitations for the Primary and Secondary Germanium and Gallium Subcategory Pollutant or... and Gallium Subcategory Pollutant or pollutant property Maximum for any 1 day Maximum for monthly...

40 CFR 421.183 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2014 CFR

2014-07-01

... and Secondary Germanium and Gallium Subcategory § 421.183 Effluent limitations guidelines representing... liquor. BAT Limitations for the Primary and Secondary Germanium and Gallium Subcategory Pollutant or... and Gallium Subcategory Pollutant or pollutant property Maximum for any 1 day Maximum for monthly...

40 CFR 421.183 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2011 CFR

2011-07-01

... and Secondary Germanium and Gallium Subcategory § 421.183 Effluent limitations guidelines representing... liquor. BAT Limitations for the Primary and Secondary Germanium and Gallium Subcategory Pollutant or... and Gallium Subcategory Pollutant or pollutant property Maximum for any 1 day Maximum for monthly...

Multifunctional ligand for use as a diagnostic or therapeutic pharmaceutical

DOEpatents

Katti, K.V.; Volkert, W.A.; Ketring, A.R.; Singh, P.R.

1996-05-14

A compound and method of making a compound for use as a diagnostic or therapeutic pharmaceutical are revealed. The ligand comprises either a phosphorous or germanium core and at least two hydrazine groups forming a ligand for bonding to a metal extending from the phosphorous or germanium core.

Germanium soup

NASA Astrophysics Data System (ADS)

Palmer, Troy A.; Alexay, Christopher C.

2006-05-01

This paper addresses the variety and impact of dispersive model variations for infrared materials and, in particular, the level to which certain optical designs are affected by this potential variation in germanium. This work offers a method for anticipating and/or minimizing the pitfalls such potential model variations may have on a candidate optical design.

Mesoporous Hollow Ge Microspheres Prepared via Molten-Salt Metallothermic Reaction for High-Performance Li-Storage Anode.

PubMed

Lin, Ning; Li, Tieqiang; Han, Ying; Zhang, Qianliang; Xu, Tianjun; Qian, Yitai

2018-03-14

Generally, Ge-based anodes are prepared by metallothermic reduction of GeO 2 with Mg at 650 °C. Herein, a molten-salt system is developed a low-temperature metallothermic reduction of GeO 2 to prepare nanostructured Ge based anode materials. Typically, mesoporous hollow Ge microspheres are prepared by reduction of GeO 2 with metallic Mg in molten ZnCl 2 (mp 292) at 350 °C. Monodispersed Ge particles are synthesized through reduction of GeO 2 with Mg in molten AlCl 3 (mp 192 °C) at 250 °C. The meso-porous Ge anode delivers the reversible capacity of 1291 mA h g -1 at 0.2 C after 150 cycles with a retention of 97.3%, 1217 mA h g -1 at 0.8 C after 400 cycles with a retention of 91.9%, and superior rate capability with a capacity of 673 mA h g -1 even at 10 C. Then, the reaction mechanism and full-cell performance of as-prepared Ge anodes are studied systemically.

Assessing microbial responses to iron enrichment in the Subarctic Northeast Pacific: Do microcosms reproduce the in situ condition?

NASA Astrophysics Data System (ADS)

Scarratt, M. G.; Marchetti, A.; Hale, M. S.; Rivkin, R. B.; Michaud, S.; Matthews, P.; Levasseur, M.; Sherry, N.; Merzouk, A.; Li, W. K. W.; Kiyosawa, H.

2006-10-01

A microcosm experiment was conducted in the NE Pacific in July 2002 to compare the microbial response between microcosms and the Subarctic Ecosystem Response to Iron-Enrichment Study (SERIES) in situ iron-enrichment experiment. Seawater microcosms (20 L) were incubated aboard ship under natural light using three treatments: (1) low-iron seawater amended with 4 nmol l -1 FeSO 4 (+Fe); (2) low-iron seawater amended with 4 nmol l -1 FeSO 4 and 86 nmol l -1 GeO 2 (+Fe+Ge); (3) seawater collected from the in situ Fe-enriched patch (PW). The +Fe+Ge treatment used germanium to control diatom growth to assess the role of diatoms in dimethylsulfoniopropionate (DMSP) production. The following variables were measured in the microcosms and in situ: chlorophyll a (chl a), nitrate ( NO3-), silicic acid (Si(OH) 4), phytoplankton abundance and species identification, bacterial abundance (including estimates of low- and high-DNA bacteria), bacterial production, bacterial specific growth rate, particulate and dissolved DMSP and dimethylsulfide (DMS) concentrations. There was little or no significant difference (ANCOVA) in the response of most variables between the +Fe and PW microcosms, but large differences were observed between both these treatments and the in situ data from the enriched patch. Chl a in all microcosms increased from ambient levels (approx. 0.5-1 μg l -1) to approx. 4.5-6.2 μg l -1 after 11 d incubation, when NO3- was fully depleted from all microcosms. During this same period, in situ chl a increased more slowly to a maximum of 2.9 μg l -1 on day 11. Nanophytoplankton and picophytoplankton were more abundant in the microcosms relative to the in situ community, which became dominated by large diatoms. Bacterial abundance was similar in the microcosms and in situ, but bacterial production was significantly higher in the microcosms. While neither DMSP d nor DMS accumulation showed significant differences between the microcosms and in situ , particulate DMSP concentrations increased significantly faster in the +Fe and PW treatments. These differences represent bottle effects resulting from the containment of the microcosms, which suppresses grazing, alters community and food web structure, enhances iron and nutrient regeneration, and isolates the community from physical transport and export processes including sinking. Thus during this experiment, the microcosms were not a good model for the in situ system in terms of the effects of iron on the phytoplankton biomass, nutrient uptake, bacterial dynamics and DMSP p production. In the germanium-amended treatment, the inhibition of diatom growth resulted in enhanced growth of other taxa and a suppression of bacterial production, leading to increased production of DMSP and DMS and strong correlations between DMSP, DMS and non-diatom phytoplankton taxa. Diatoms did not contribute significantly to particulate DMSP concentrations.

Simulation of how a geo-engineering intervention to restore arctic sea ice might work in practice

NASA Astrophysics Data System (ADS)

Jackson, L. S.; Crook, J. A.; Forster, P.; Jarvis, A.; Leedal, D.; Ridgwell, A. J.; Vaughan, N.

2013-12-01

The declining trend in annual minimum Arctic sea ice coverage and years of more pronounced drops like 2007 and 2012 raise the prospect of an Arctic Ocean largely free of sea ice in late summer and the potential for a climate crisis or emergency. In a novel computer simulation, we treated one realisation of a climate model (HadGEM2) as the real world and tried to restore its Arctic sea ice by the rapid deployment of geo-engineering with emission of SO2 into the Arctic stratosphere. The objective was to restore the annual minimum Arctic sea ice coverage to levels seen in the late twentieth century using as little geo-engineering as possible. We took intervention decisions as one might do in the real world: by committee, using a limited set of uncertain 'observations' from our simulated world and using models and control theory to plan the best intervention strategy for the coming year - so learning as we went and being thrown off course by future volcanoes and technological breakdowns. Uncertainties in real world observations were simulated by applying noise to emerging results from the climate model. Volcanic forcing of twenty-first century climate was included with the timing and magnitude of the simulated eruptions unknown by the 'geo-engineers' until after the year of the eruption. Monitoring of Arctic sea ice with the option to intervene with SO2 emissions started from 2018 and continued to 2075. Simulated SO2 emissions were made in January-May each year at a latitude of 79o N and an altitude within the range of contemporary tanker aircraft. The magnitude of emissions was chosen annually using a model predictive control process calibrated using results from CMIP5 models (excluding HadGEM2), using the simplified climate model MAGICC and assimilation of emerging annual results from the HadGEM2 'real world'. We found that doubts in the minds of the 'geo-engineers' of the effectiveness and the side effects of their past intervention, and the veracity of the models used for planning intervention were a constant feature of the simulation. As a result, their assumptions and intervention approaches were considerably revised as the simulation progressed. Side effects of the geo-engineering were difficult to explicitly determine without a control experiment. Nevertheless, we found wide spread changes in precipitation that were believed to be due to the geo-engineering - a later control experiment confirmed this belief. On termination of the SO2 geo-engineering, northern hemisphere temperatures rose sharply and Arctic sea ice area dropped dramatically. These termination effects were so large that attribution to the geo-engineering cessation was unambiguous.

Comparative Analysis of NOAA REFM and SNB3GEO Tools for the Forecast of the Fluxes of High-Energy Electrons at GEO

NASA Technical Reports Server (NTRS)

Balikhin, M. A.; Rodriguez, J. V.; Boynton, R. J.; Walker, S. N.; Aryan, Homayon; Sibeck, D. G.; Billings, S. A.

2016-01-01

Reliable forecasts of relativistic electrons at geostationary orbit (GEO) are important for the mitigation of their hazardous effects on spacecraft at GEO. For a number of years the Space Weather Prediction Center at NOAA has provided advanced online forecasts of the fluence of electrons with energy >2 MeV at GEO using the Relativistic Electron Forecast Model (REFM). The REFM forecasts are based on real-time solar wind speed observations at L1. The high reliability of this forecasting tool serves as a benchmark for the assessment of other forecasting tools. Since 2012 the Sheffield SNB3GEO model has been operating online, providing a 24 h ahead forecast of the same fluxes. In addition to solar wind speed, the SNB3GEO forecasts use solar wind density and interplanetary magnetic field B(sub z) observations at L1. The period of joint operation of both of these forecasts has been used to compare their accuracy. Daily averaged measurements of electron fluxes by GOES 13 have been used to estimate the prediction efficiency of both forecasting tools. To assess the reliability of both models to forecast infrequent events of very high fluxes, the Heidke skill score was employed. The results obtained indicate that SNB3GEO provides a more accurate 1 day ahead forecast when compared to REFM. It is shown that the correction methodology utilized by REFM potentially can improve the SNB3GEO forecast.

Comparative analysis of NOAA REFM and SNB3GEO tools for the forecast of the fluxes of high-energy electrons at GEO.

PubMed

Balikhin, M A; Rodriguez, J V; Boynton, R J; Walker, S N; Aryan, H; Sibeck, D G; Billings, S A

2016-01-01

Reliable forecasts of relativistic electrons at geostationary orbit (GEO) are important for the mitigation of their hazardous effects on spacecraft at GEO. For a number of years the Space Weather Prediction Center at NOAA has provided advanced online forecasts of the fluence of electrons with energy >2 MeV at GEO using the Relativistic Electron Forecast Model (REFM). The REFM forecasts are based on real-time solar wind speed observations at L1. The high reliability of this forecasting tool serves as a benchmark for the assessment of other forecasting tools. Since 2012 the Sheffield SNB 3 GEO model has been operating online, providing a 24 h ahead forecast of the same fluxes. In addition to solar wind speed, the SNB 3 GEO forecasts use solar wind density and interplanetary magnetic field B z observations at L1.The period of joint operation of both of these forecasts has been used to compare their accuracy. Daily averaged measurements of electron fluxes by GOES 13 have been used to estimate the prediction efficiency of both forecasting tools. To assess the reliability of both models to forecast infrequent events of very high fluxes, the Heidke skill score was employed. The results obtained indicate that SNB 3 GEO provides a more accurate 1 day ahead forecast when compared to REFM. It is shown that the correction methodology utilized by REFM potentially can improve the SNB 3 GEO forecast.

Two Model-Based Methods for Policy Analyses of Fine Particulate Matter Control in China: Source Apportionment and Source Sensitivity

NASA Astrophysics Data System (ADS)

Li, X.; Zhang, Y.; Zheng, B.; Zhang, Q.; He, K.

2013-12-01

Anthropogenic emissions have been controlled in recent years in China to mitigate fine particulate matter (PM2.5) pollution. Recent studies show that sulfate dioxide (SO2)-only control cannot reduce total PM2.5 levels efficiently. Other species such as nitrogen oxide, ammonia, black carbon, and organic carbon may be equally important during particular seasons. Furthermore, each species is emitted from several anthropogenic sectors (e.g., industry, power plant, transportation, residential and agriculture). On the other hand, contribution of one emission sector to PM2.5 represents contributions of all species in this sector. In this work, two model-based methods are used to identify the most influential emission sectors and areas to PM2.5. The first method is the source apportionment (SA) based on the Particulate Source Apportionment Technology (PSAT) available in the Comprehensive Air Quality Model with extensions (CAMx) driven by meteorological predictions of the Weather Research and Forecast (WRF) model. The second method is the source sensitivity (SS) based on an adjoint integration technique (AIT) available in the GEOS-Chem model. The SA method attributes simulated PM2.5 concentrations to each emission group, while the SS method calculates their sensitivity to each emission group, accounting for the non-linear relationship between PM2.5 and its precursors. Despite their differences, the complementary nature of the two methods enables a complete analysis of source-receptor relationships to support emission control policies. Our objectives are to quantify the contributions of each emission group/area to PM2.5 in the receptor areas and to intercompare results from the two methods to gain a comprehensive understanding of the role of emission sources in PM2.5 formation. The results will be compared in terms of the magnitudes and rankings of SS or SA of emitted species and emission groups/areas. GEOS-Chem with AIT is applied over East Asia at a horizontal grid resolution of 0.5° (Lat) × 0.67° (Lon). WRF/CAMx with PSAT is applied to nested grids: 36-km × 36-km over China and 12-km × 12-km over northern China. These simulations are performed for 2006 and 2011. Beijing and northern Hebei are selected as representative receptor areas. Simulated surface concentrations by both models are evaluated with available observations in China. Focusing on inorganic aerosols (sulfate, nitrate and ammonium), preliminary SS results from GEOS-Chem/AIT at Beijing identify the top three major emission sectors to be agriculture, residential, and transportation in winter and agriculture, industry and power plant in summer. The top four source areas are northern Hebei, local, Neimenggu, and Liaoning in winter and northern Hebei, local, Shandong, and southern Hebei in summer. The synthesis of SS and SA for influential emission groups or areas from this work will provide a quantitative basis for emission control strategy development and policy making for PM2.5 control in China.

Effect of Germanium on the TiO2 Photoanode for Dye Sensitized Solar Cell Applications. A Potential Sintering Aid

NASA Astrophysics Data System (ADS)

Ahmad, M. S.; Pandey, AK; Rahim, N. A.

2018-05-01

Anatase titanium-germanium (TiO2-Ge) nanocomposite has been prepared by using colloidal suspension process and investigated for photoanode to be used in dye sensitized solar cell. Ge possesses lower band gap energy compared to TiO2 and has the capability to absorb infrared region of solar spectrum. Its remarkable absorption and good electron transfer ability due to lower band gap energy makes it a potential candidate material in the field of DSSCs to counter important disadvantages such as high probability of electron recombination reactions and absorption of small region (UV region) of solar spectrum. Another advantage is its low sintering temperature which proved to be an added advantage to increase inter-particle contact which in turn leads to improved electron transfer. Scanning electron microscopy (SEM), uv-vis spectroscopy and electron impedance spectroscopy (EIS) have been employed to evaluate the effect of Ge on TiO2photoanode.

Detached Bridgman Growth of Germanium and Germanium-Silicon Alloy Crystals

NASA Technical Reports Server (NTRS)

Szofran, F. R.; Volz, M. P.; Schweizer, M.; Kaiser, N.; Cobb, S. D.; Motakef, S.; Vujisic, L. J.; Croell, A.; Dold, P.; Rose, M. Franklin (Technical Monitor)

2001-01-01

Earth based experiments on the science of detached crystal growth are being conducted on germanium and germanium-silicon alloys (2at% Si average composition) in preparation for a series of experiments aboard the International Space Station (ISS) to differentiate among proposed mechanisms contributing to detachment. Sessile drop measurements were first carried out for a large number of substrates made of potential ampoule materials to determine the contact angles and the surface tension as a function of temperature and composition. The process atmosphere and duration of the experiment (for some cases) were also found to have significant influence on the wetting angle. Growth experiments have used pyrolytic boron nitride (pBN) and fused silica ampoules with the majority of the detached results occurring predictably in the pBN. The contact angles were 173 deg (Ge) and 165 deg (GeSi) for pBN. For fused silica, the contact angle decreases to an equilibrium value with duration of measurement ranging from 150 to 117 deg (Ge), 129 to 100 deg (GeSi). Forming gas (Ar + 2% H2) and vacuum have been used in the growth ampoules. With gas in the ampoule, a variation of the temperature profile during growth has been used to control the pressure difference between the top of the melt and the volume below the melt caused by detachment of the growing crystal. The stability of detachment has been modeled and substantial insight has been gained into the reasons that detachment has most often been observed in reduced gravity but nonetheless has occurred randomly even there. An empirical model for the conditions necessary to achieve sufficient stability to maintain detached growth for extended periods has been developed and will be presented. Methods for determining the nature and extent of detachment include profilometry and optical and electron microscopy. This surface study is the subject of another presentation at this Congress. Results in this presentation will show that we have established the effects of different ampoule materials, temperature profiles, pressure differences, and silicon concentrations and that samples that are nearly completely detached can be grown repeatedly.

Synthesis of germanium nanocrystals in high temperature supercritical CO2

NASA Astrophysics Data System (ADS)

Lu, Xianmao; Korgel, Brian A.; Johnston, Keith P.

2005-07-01

Germanium nanocrystals were synthesized in supercritical (sc) CO2 by thermolysis of diphenylgermane (DPG) or tetraethylgermane (TEG) with octanol as a capping ligand at 500 °C and 27.6 MPa. The Ge nanocrystals were characterized with high resolution transmission electron microscopy (HRTEM), energy-dispersive x-ray spectroscopy (EDS), and x-ray diffraction (XRD). On the basis of TEM, the mean diameters of the nanocrystals made from DPG and TEG were 10.1 and 5.6 nm, respectively. The synthesis in sc-CO2 produced much less organic contamination compared with similar reactions in organic supercritical fluids. When the same reaction of DPG with octanol was performed in the gas phase without CO2 present, bulk Ge crystals were formed instead of nanocrystals. Thus, the solvation of the hydrocarbon ligands by CO2 was sufficient to provide steric stabilization. The presence of steric stabilization in CO2 at a reduced temperature of 2.5, with a reduced solvent density of only 0.4, may be attributed to a reduction in the differences between ligand-ligand interactions and ligand-CO2 interactions relative to thermal energy.

Improvement of the GEOS-5 AGCM upon Updating the Air-Sea Roughness Parameterization

NASA Technical Reports Server (NTRS)

Garfinkel, C. I.; Molod, A.; Oman, L. D.; Song, I.-S.

2011-01-01

The impact of an air-sea roughness parameterization over the ocean that more closely matches recent observations of air-sea exchange is examined in the NASA Goddard Earth Observing System, version 5 (GEOS-5) atmospheric general circulation model. Surface wind biases in the GEOS-5 AGCM are decreased by up to 1.2m/s. The new parameterization also has implications aloft as improvements extend into the stratosphere. Many other GCMs (both for operational weather forecasting and climate) use a similar class of parameterization for their air-sea roughness scheme. We therefore expect that results from GEOS-5 are relevant to other models as well.

Dissolution chemistry and biocompatibility of silicon- and germanium-based semiconductors for transient electronics.

PubMed

Kang, Seung-Kyun; Park, Gayoung; Kim, Kyungmin; Hwang, Suk-Won; Cheng, Huanyu; Shin, Jiho; Chung, Sangjin; Kim, Minjin; Yin, Lan; Lee, Jeong Chul; Lee, Kyung-Mi; Rogers, John A

2015-05-06

Semiconducting materials are central to the development of high-performance electronics that are capable of dissolving completely when immersed in aqueous solutions, groundwater, or biofluids, for applications in temporary biomedical implants, environmentally degradable sensors, and other systems. The results reported here include comprehensive studies of the dissolution by hydrolysis of polycrystalline silicon, amorphous silicon, silicon-germanium, and germanium in aqueous solutions of various pH values and temperatures. In vitro cellular toxicity evaluations demonstrate the biocompatibility of the materials and end products of dissolution, thereby supporting their potential for use in biodegradable electronics. A fully dissolvable thin-film solar cell illustrates the ability to integrate these semiconductors into functional systems.

Removal of the long-lived {sup 222}Rn daughters from steel and germanium surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wojcik, Marcin; Zuzel, Grzegorz; Majorovits, Bela

Removal of the long-lived {sup 222}Rn daughters ({sup 210}Pb, {sup 210}Bi and {sup 210}Po) from stainless steel and germanium surfaces was investigated. As cleaning technique etching was applied to samples in a form of discs exposed earlier to a strong radon source. Reduction of the {sup 210}Pb activity was tested using a HPGe spectrometer, for {sup 210}Bi a beta spectrometer and for {sup 210}Po an alpha spectrometer was used. According to the conducted measurements all the isotopes were removed very efficiently from germanium. Results obtained for stainless steel were worse but still better than those achieved for copper.

A self-aligned dry etching method for mechanical strain enhancement of germanium and its uniformity improvement for photonic applications

NASA Astrophysics Data System (ADS)

Lin, Yiding; Ma, Danhao; Lee, Kwang Hong; Michel, Jurgen; Tan, Chuan Seng

2018-02-01

A self-aligned dry etching method was proposed and verified theoretically to enhance the magnitude and simultaneously improve the uniformity of the tensile strain in a germanium (Ge) wave-guide (WG), with the help of tensile-stressed SiN stressor at the WG sidewalls. The SiN-strained germanium-on-insulator (GOI) WG was also experimentally demonstrated. Significant tensile strain was observed in the Ge material via micro-Raman measurements. This method could potentially facilitate a Ge photodetector with its optical detection range extended further towards longer wavelength and to be comparable with that of state-of-the-art InGaAs detectors.

Effect of germanium concentrations on tunnelling current calculation of Si/Si1-xGex/Si heterojunction bipolar transistor

NASA Astrophysics Data System (ADS)

Hasanah, L.; Suhendi, E.; Khairrurijal

2018-05-01

Tunelling current calculation on Si/Si1-xGex/Si heterojunction bipolar transistor was carried out by including the coupling between transversal and longitudinal components of electron motion. The calculation results indicated that the coupling between kinetic energy in parallel and perpendicular to S1-xGex barrier surface affected tunneling current significantly when electron velocity was faster than 1x105 m/s. This analytical tunneling current model was then used to study how the germanium concentration in base to Si/Si1-xGex/Si heterojunction bipolar transistor influenced the tunneling current. It is obtained that tunneling current increased as the germanium concentration given in base decreased.

High temperature material interactions of thermoelectric systems using silicon germanium.

NASA Technical Reports Server (NTRS)

Stapfer, G.; Truscello, V. C.

1973-01-01

The efficient use of silicon germanium thermoelectric material for radioisotope thermoelectric generators (RTG) is achieved by operation at relatively high temperatures. The insulation technique which is most appropriate for this application uses multiple layers of molybdenum foil and astroquartz. Even so, the long term operation of these materials at elevated temperatures can cause material interaction to occur within the system. To investigate these material interactions, the Jet Propulsion Laboratory is currently testing a number of thermoelectric modules which use four silicon germanium thermoelectric couples in conjunction with the multifoil thermal insulation. The paper discusses the results of the ongoing four-couple module test program and correlates test results with those of a basic material test program.

Activity measurements of 55Fe by two different methods

NASA Astrophysics Data System (ADS)

da Cruz, Paulo A. L.; Iwahara, Akira; da Silva, Carlos J.; Poledna, Roberto; Loureiro, Jamir S.; da Silva, Monica A. L.; Ruzzarin, Anelise

2018-03-01

A calibrated germanium detector and CIEMAT/NIST liquid scintillation method were used in the standardization of solution of 55Fe coming from a key-comparison BIPM. Commercial cocktails were used in source preparation for activity measurements in CIEMAT/NIST method. Measurements were performed in Liquid Scintillation Counter. In the germanium counting method standard point sources were prepared for obtaining atomic number versus efficiency curve of the detector in order to obtain the efficiency of 5.9 keV KX-ray of 55Fe by interpolation. The activity concentrations obtained were 508.17 ± 3.56 and 509.95 ± 16.20 kBq/g for CIEMAT/NIST and germanium methods, respectively.

GeoLab: A Geological Workstation for Future Missions

NASA Technical Reports Server (NTRS)

Evans, Cynthia; Calaway, Michael; Bell, Mary Sue; Li, Zheng; Tong, Shuo; Zhong, Ye; Dahiwala, Ravi

2014-01-01

The GeoLab glovebox was, until November 2012, fully integrated into NASA's Deep Space Habitat (DSH) Analog Testbed. The conceptual design for GeoLab came from several sources, including current research instruments (Microgravity Science Glovebox) used on the International Space Station, existing Astromaterials Curation Laboratory hardware and clean room procedures, and mission scenarios developed for earlier programs. GeoLab allowed NASA scientists to test science operations related to contained sample examination during simulated exploration missions. The team demonstrated science operations that enhance theThe GeoLab glovebox was, until November 2012, fully integrated into NASA's Deep Space Habitat (DSH) Analog Testbed. The conceptual design for GeoLab came from several sources, including current research instruments (Microgravity Science Glovebox) used on the International Space Station, existing Astromaterials Curation Laboratory hardware and clean room procedures, and mission scenarios developed for earlier programs. GeoLab allowed NASA scientists to test science operations related to contained sample examination during simulated exploration missions. The team demonstrated science operations that enhance the early scientific returns from future missions and ensure that the best samples are selected for Earth return. The facility was also designed to foster the development of instrument technology. Since 2009, when GeoLab design and construction began, the GeoLab team [a group of scientists from the Astromaterials Acquisition and Curation Office within the Astromaterials Research and Exploration Science (ARES) Directorate at JSC] has progressively developed and reconfigured the GeoLab hardware and software interfaces and developed test objectives, which were to 1) determine requirements and strategies for sample handling and prioritization for geological operations on other planetary surfaces, 2) assess the scientific contribution of selective in-situ sample characterization for mission planning, operations, and sample prioritization, 3) evaluate analytical instruments and tools for providing efficient and meaningful data in advance of sample return and 4) identify science operations that leverage human presence with robotic tools. In the first year of tests (2010), GeoLab examined basic glovebox operations performed by one and two crewmembers and science operations performed by a remote science team. The 2010 tests also examined the efficacy of basic sample characterization [descriptions, microscopic imagery, X-ray fluorescence (XRF) analyses] and feedback to the science team. In year 2 (2011), the GeoLab team tested enhanced software and interfaces for the crew and science team (including Web-based and mobile device displays) and demonstrated laboratory configurability with a new diagnostic instrument (the Multispectral Microscopic Imager from the JPL and Arizona State University). In year 3 (2012), the GeoLab team installed and tested a robotic sample manipulator and evaluated robotic-human interfaces for science operations.

The GMAO Hybrid Ensemble-Variational Atmospheric Data Assimilation System: Version 2.0

NASA Technical Reports Server (NTRS)

Todling, Ricardo; El Akkraoui, Amal

2018-01-01

This document describes the implementation and usage of the Goddard Earth Observing System (GEOS) Hybrid Ensemble-Variational Atmospheric Data Assimilation System (Hybrid EVADAS). Its aim is to provide comprehensive guidance to users of GEOS ADAS interested in experimenting with its hybrid functionalities. The document is also aimed at providing a short summary of the state-of-science in this release of the hybrid system. As explained here, the ensemble data assimilation system (EnADAS) mechanism added to GEOS ADAS to enable hybrid data assimilation applications has been introduced to the pre-existing machinery of GEOS in the most non-intrusive possible way. Only very minor changes have been made to the original scripts controlling GEOS ADAS with the objective of facilitating its usage by both researchers and the GMAO's near-real-time Forward Processing applications. In a hybrid scenario two data assimilation systems run concurrently in a two-way feedback mode such that: the ensemble provides background ensemble perturbations required by the ADAS deterministic (typically high resolution) hybrid analysis; and the deterministic ADAS provides analysis information for recentering of the EnADAS analyses and information necessary to ensure that observation bias correction procedures are consistent between both the deterministic ADAS and the EnADAS. The nonintrusive approach to introducing hybrid capability to GEOS ADAS means, in particular, that previously existing features continue to be available. Thus, not only is this upgraded version of GEOS ADAS capable of supporting new applications such as Hybrid 3D-Var, 3D-EnVar, 4D-EnVar and Hybrid 4D-EnVar, it remains possible to use GEOS ADAS in its traditional 3D-Var mode which has been used in both MERRA and MERRA-2. Furthermore, as described in this document, GEOS ADAS also supports a configuration for exercising a purely ensemble-based assimilation strategy which can be fully decoupled from its variational component. We should point out that Release 1.0 of this document was made available to GMAO in mid-2013, when we introduced Hybrid 3D-Var capability to GEOS ADAS. This initial version of the documentation included a considerably different state-of-science introductory section but many of the same detailed description of the mechanisms of GEOS EnADAS. We are glad to report that a few of the desirable Future Works listed in Release 1.0 have now been added to the present version of GEOS EnADAS. These include the ability to exercise an Ensemble Prediction System that uses the ensemble analyses of GEOS EnADAS and (a very early, but functional version of) a tool to support Ensemble Forecast Sensitivity and Observation Impact applications.

Cationic aza-macrocyclic complexes of germanium(II) and silicon(IV).

PubMed

Everett, Matthew; Jolleys, Andrew; Levason, William; Light, Mark E; Pugh, David; Reid, Gillian

2015-12-28

[GeCl2(dioxane)] reacts with the neutral aza-macrocyclic ligands L, L = Me3tacn (1,4,7-trimethyl-1,4,7-triazacyclononane), Me4cyclen (1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane) or Me4cyclam (1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) and two mol. equiv. of Me3SiO3SCF3 in thf solution to yield the unusual and hydrolytically very sensitive [Ge(L)][O3SCF3]2 as white solids in moderate yield. Using shorter reaction times [Ge(Me3tacn)]Cl2 and [Ge(Me3tacn)]Cl[O3SCF3] were also isolated; the preparation of [Ge(Me4cyclen)][GeCl3]2 is also described. The structures of the Me3tacn complexes show κ(3)-coordination of the macrocycle, with the anions interacting only weakly to produce very distorted five- or six-coordination at germanium. In contrast, the structure of [Ge(Me4cyclen)][O3SCF3]2 shows no anion interactions, and a distorted square planar geometry at germanium from coordination to the tetra-aza macrocycle. Crystal structures of the Si(iv) complexes, [SiCl3(Me3tacn)]Y (Y = O3SCF3, BAr(F); [B{3,5-(CF3)2C6H3}4]) and [SiHCl2(Me3tacn)][BAr(F)], obtained from reaction of SiCl4 or SiHCl3 with Me3tacn, followed by addition of either Me3SiO3SCF3 or Na[BAr(F)], contain distorted octahedral cations, with facialκ(3)-coordinated Me3tacn. The open-chain triamine, Me2NCH2CH2N(Me)CH2CH2NMe2 (pmdta), forms [SiCl3(pmdta)][BAr(F)] and [SiBr3(pmdta)][BAr(F)] under similar conditions, containing mer-octahedral cations.

Assessment of the magnitude and recent trends in satellite-derived ground-level nitrogen dioxide over North America

NASA Astrophysics Data System (ADS)

Kharol, S. K.; Martin, R. V.; Philip, S.; Boys, B.; Lamsal, L. N.; Jerrett, M.; Brauer, M.; Crouse, D. L.; McLinden, C.; Burnett, R. T.

2015-10-01

We estimate ground-level nitrogen dioxide (NO2) concentrations from the OMI (Ozone Monitoring Instrument) over North America for the period 2005-2012. A chemical transport model (GEOS-Chem) is used to account for effects of the NO2 profile on the column retrieval, and to relate OMI NO2 columns to ground-level concentrations. The magnitude of the period-mean OMI-derived NO2 concentrations is evaluated versus in situ measurements from air quality networks yielding a significant spatial correlation (r = 0.81) but OMI-derived values are lower with a slope of 0.4. Comparison of the in situ concentrations versus spatially resolved concentrations estimated from land use regression models reveals that this difference partially arises from representativeness difference due to preferential placement of in situ monitors at locations with enhanced NO2, coupled with the OMI horizontal resolution. In situ observations provide information about local concentrations while OMI offers area-averaged information. The remaining difference is less readily explained and appears to include a combination of the effects of local unresolved geophysical processes affecting both the NO2 retrieval and the vertical profile used to relate the column to ground level. We also evaluate trends over North America from OMI and in situ measurements for the period of 2005-2012. OMI derived ground-level NO2 well reproduces the spatial pattern of the in situ trends (r = 0.77) and the slope of 0.4 versus the trend from in situ monitors is consistent with the slope versus mean concentrations. Absolute regional trends inferred from in situ measurements alone may overestimate area average changes. Nonetheless coincidently sampled ground-level NO2 concentrations from OMI and in situ measurements for 2005-2012 exhibit similar relative decreases over Eastern (-6.5 ± 2.0%/yr, -7.1 ± 1.3%/yr), Western (-4.5 ± 1.1%/yr, -6.5 ± 0.7%/yr) and Central (-3.3 ± 2.3%/yr, -4.1 ± 0.8%/yr) North America.

Potential impacts on groundwater resources of deep CO2 storage: natural analogues for assessing potential chemical effects

NASA Astrophysics Data System (ADS)

Lions, J.; Gale, I.; May, F.; Nygaard, E.; Ruetters, H.; Beaubien, S.; Sohrabi, M.; Hatzignatiou, D. G.; CO2GeoNet Members involved in the present study Team

2011-12-01

Carbon dioxide Capture and Storage (CCS) is considered as one of the promising options for reducing atmospheric emissions of CO2 related to human activities. One of the main concerns associated with the geological storage of CO2 is that the CO2 may leak from the intended storage formation, migrate to the near-surface environment and, eventually, escape from the ground. This is a concern because such leakage may affect aquifers overlying the storage site and containing freshwater that may be used for drinking, industry and agriculture. The IEA Greenhouse Gas R&D Programme (IEAGHG) recently commissioned the CO2GeoNet Association to undertake a review of published and unpublished literature on this topic with the aim of summarizing 'state of the art' knowledge and identifying knowledge gaps and research priorities in this field. Work carried out by various CO2GeoNet members was also used in this study. This study identifies possible areas of conflict by combining available datasets to map the global and regional superposition of deep saline formations (DSF) suitable for CO2 storage and overlying fresh groundwater resources. A scenario classification is developed for the various geological settings where conflict could occur. The study proposes two approaches to address the potential impact mechanisms of CO2 storage projects on the hydrodynamics and chemistry of shallow groundwater. The first classifies and synthesizes changes of water quality observed in natural/industrial analogues and in laboratory experiments. The second reviews hydrodynamic and geochemical models, including coupled multiphase flow and reactive transport. Various models are discussed in terms of their advantages and limitations, with conclusions on possible impacts on groundwater resources. Possible mitigation options to stop or control CO2 leakage are assessed. The effect of CO2 pressure in the host DSF and the potential effects on shallow aquifers are also examined. The study provides a review of CO2 storage-specific regulations in the main countries undertaking CCS evaluation and research. It aims to identify the constraints imposed by existing regulations on the protection of groundwater resources and highlight the inconsistencies and gaps between CCS regulations and Water Protection regulations. The present paper focuses specifically on potential risks on groundwater quality caused by CO2 storage in DSF assessed via natural CO2 analogues from both the literature and detailed European case studies.

Temperature-Dependent Compensation and Optical Quenching by Thermal Oxygen Donors in Germanium

NASA Technical Reports Server (NTRS)

Watson, D.; Guptill, M.; Huffman, J.; Krabach, T.; Raines, S.

1994-01-01

Photothermal ionization spectroscopy of germanium, doped in the impurity-band conduction range with gallium acceptors and with thermal oxygen donors, reveals that the donors and acceptors compensate each other at temperatures higher than about 5K, but that the impurities coexist as neutral donors and acceptors at lower temperatures.

Hall Effect Spintronics

DTIC Science & Technology

2014-01-01

ferromagnetic films with perpendicular anisotropy were examined, and finally, the magnetoresistance and Hall effect in Manganese- doped Germanium was...interest in ferromagnetic semiconductors. Germanium doped with Mn is particularly interesting Distribution A: Approved for public release...unavoidable, and doped films are strongly inhomogeneous with GexMny, metallic precipitates coexisting with Mn-rich regions and Mn dilute matrix

A Modified Monte Carlo Method for Carrier Transport in Germanium, Free of Isotropic Rates

NASA Astrophysics Data System (ADS)

Sundqvist, Kyle

2010-03-01

We present a new method for carrier transport simulation, relevant for high-purity germanium < 100 > at a temperature of 40 mK. In this system, the scattering of electrons and holes is dominated by spontaneous phonon emission. Free carriers are always out of equilibrium with the lattice. We must also properly account for directional effects due to band structure, but there are many cautions in the literature about treating germanium in particular. These objections arise because the germanium electron system is anisotropic to an extreme degree, while standard Monte Carlo algorithms maintain a reliance on isotropic, integrated rates. We re-examine Fermi's Golden Rule to produce a Monte Carlo method free of isotropic rates. Traditional Monte Carlo codes implement particle scattering based on an isotropically averaged rate, followed by a separate selection of the particle's final state via a momentum-dependent probability. In our method, the kernel of Fermi's Golden Rule produces analytical, bivariate rates which allow for the simultaneous choice of scatter and final state selection. Energy and momentum are automatically conserved. We compare our results to experimental data.

Advances and Directions for the Intelligent Systems for Geosciences Research Community: Updates and Opportunities from the NSF EarthCube IS-GEO RCN

NASA Astrophysics Data System (ADS)

Pierce, S. A.

2017-12-01

The Earthcube Intelligent Systems for Geosciences Research Collaboration Network (IS-GEO RCN) represents an emerging community of interdisciplinary researchers aiming to create fundamental new capabilities for understanding Earth systems. Collaborative efforts across IS-GEO fields of study offer opportunities to accelerate scientific discovery and understanding. The IS-GEO community has an active membership of approximately 65 researchers and includes researchers from across the US, international members, and an early career committee. Current working groups are open to new participants and are focused on four thematic areas with regular coordination meetings and upcoming sessions at professional conferences. (1) The Sensor-based data Collection and Integration Working group looks at techniques for analyzing and integrating of information from heterogeneous sources, with a possible application for early warning systems. (2) The Geoscience Case Studies Working group is creating benchmark data sets to enable new collaborations between geoscientists and data scientists. (3) The Geo-Simulations Working group is evaluating the state of the art in practices for parametrizations, scales, and model integration. (4) The Education Working group is gathering, organizing and collecting all the materials from the different IS-GEO courses. Innovative IS-GEO applications will help researchers overcome common challenges while will redefining the frontiers of discovery across fields and disciplines. (Visit IS-GEO.org for more information or to sign up for any of the working groups.)

How can LCA approaches contribute to improve geo-cycles management

NASA Astrophysics Data System (ADS)

Carreiras, M.; Ferreira, A. J. D.; Esteves, T. C. J.; Delgado, F.; Andrade, F.; Franco, J.; Pereira, C. D.

2012-04-01

Climate change and land use have become a major challenge for mankind and the natural environment. Greenhouse gas (GHG) emissions released into the atmosphere in ever rapidly growing volumes are most likely to be responsible for this change. Carbon dioxide gas (CO2) is suggested to be the main cause of global warming. Carbon reduction is the key to preventing this, for example, by enhancing energy efficiency and mitigating carbon emissions by means of green energy and adjusting the use of natural resources. Different activities produce distinguish impacts, and each product generates specific impacts on nature. The impact of man activities in the geo-cycles is of paramount importance in what concerns long term sustainability. Nevertheless, the environmental and sustainability impacts of different approaches and techniques of ecosystem management is a difficult question that can be assessed using LCA techniques LCA is a technique to assess environmental impacts associated with all the stages of a product's life from-cradle-to-grave. Based on that, LCA can be effective in supporting the assessment of decision making on complex sustainability issues because it can integrate the diversity of impacts categories guise and it can be adapted to a large variety of contexts. By incorporating quantitative data LCA allows decision makers to include a full range of economic, environmental, social and technical criteria. The integrated framework is configured such that the pros and cons of alternative environmental and energy strategies can be measured in terms of their ability to achieve the overall goals and objectives of the sustainable development, while satisfying the pollution control requirements. Because it is holistic, integrate and dynamic, this approach represents a state of the art tool for enhance the sustainable development of a sector, allowing a more transparent and participated management, a basic instrument for improved competitiveness. This approach may serve as a basis for prioritizing industrial technologies, procedures or materials, based on the reduction of impacts. The ECODEEP project intents to contribute to the competitiveness of the national agri-food sector in particular the Central Region of Portugal. Through the development of eco-efficiency tools it allows a more careful management of inputs, optimizing consumption energy and raw materials. ECODEEP seeks to improve the performance of the sector, allowing an improvement of production processes and a reduction of the investment on end-of-line solutions, therefore reducing products costs, which become more competitive, while reducing the impact on geo-cycles and the ecosystems. The overall purpose of this paper is, based on a case study, discuss the use of LCA approach to improve overall competitiveness while reducing the impact over the geo-cycles and the environment in general.

Assessing the potential roles of silicon and germanium phthalocyanines in planar heterojunction organic photovoltaic devices and how pentafluoro phenoxylation can enhance π-π interactions and device performance.

PubMed

Lessard, Benoît H; White, Robin T; Al-Amar, Mohammad; Plint, Trevor; Castrucci, Jeffrey S; Josey, David S; Lu, Zheng-Hong; Bender, Timothy P

2015-03-11

In this study, we have assessed the potential application of dichloro silicon phthalocyanine (Cl2-SiPc) and dichloro germanium phthalocyanine (Cl2-GePc) in modern planar heterojunction organic photovoltaic (PHJ OPV) devices. We have determined that Cl2-SiPc can act as an electron donating material when paired with C60 and that Cl2-SiPc or Cl2-GePc can also act as an electron acceptor material when paired with pentacene. These two materials enabled the harvesting of triplet energy resulting from the singlet fission process in pentacene. However, contributions to the generation of photocurrent were observed for Cl2-SiPc with no evidence of photocurrent contribution from Cl2-GePc. The result of our initial assessment established the potential for the application of SiPc and GePc in PHJ OPV devices. Thereafter, bis(pentafluoro phenoxy) silicon phthalocyanine (F10-SiPc) and bis(pentafluoro phenoxy) germanium phthalocyanine (F10-GePc) were synthesized and characterized. During thermal processing, it was discovered that F10-SiPc and F10-GePc underwent a reaction forming small amounts of difluoro SiPc (F2-SiPc) and difluoro GePc (F2-GePc). This undesirable reaction could be circumvented for F10-SiPc but not for F10-GePc. Using single crystal X-ray diffraction, it was determined that F10-SiPc has significantly enhanced π-π interactions compared with that of Cl2-SiPc, which had little to none. Unoptimized PHJ OPV devices based on F10-SiPc were fabricated and directly compared to those constructed from Cl2-SiPc, and in all cases, PHJ OPV devices based on F10-SiPc had significantly improved device characteristics compared to Cl2-SiPc.

A model for the high-temperature transport properties of heavily doped n-type silicon-germanium alloys

NASA Technical Reports Server (NTRS)

Vining, Cronin B.

1991-01-01

A model is presented for the high-temperature transport properties of large-grain-size, heavily doped n-type silicon-germanium alloys. Electron and phonon transport coefficients are calculated using standard Boltzmann equation expressions in the relaxation time approximation. Good agreement with experiment is found by considering acoustic phonon and ionized impurity scattering for electrons, and phonon-phonon, point defect, and electron-phonon scattering for phonons. The parameters describing electron transport in heavily doped and lightly doped materials are significantly different and suggest that most carriers in heavily doped materials are in a band formed largely from impurity states. The maximum dimensionless thermoelectric figure of merit for single-crystal, n-type Si(0.8)Ge(0.2) at 1300 K is estimated at ZT about 1.13 with an optimum carrier concentration of n about 2.9 x 10 to the 20th/cu cm.

Application of gamma imaging techniques for the characterisation of position sensitive gamma detectors

NASA Astrophysics Data System (ADS)

Habermann, T.; Didierjean, F.; Duchêne, G.; Filliger, M.; Gerl, J.; Kojouharov, I.; Li, G.; Pietralla, N.; Schaffner, H.; Sigward, M.-H.

2017-11-01

A device to characterize position-sensitive germanium detectors has been implemented at GSI. The main component of this so called scanning table is a gamma camera that is capable of producing online 2D images of the scanned detector by means of a PET technique. To calibrate the gamma camera Compton imaging is employed. The 2D data can be processed further offline to obtain depth information. Of main interest is the response of the scanned detector in terms of the digitized pulse shapes from the preamplifier. This is an important input for pulse-shape analysis algorithms as they are in use for gamma tracking arrays in gamma spectroscopy. To validate the scanning table, a comparison of its results with a second scanning table implemented at the IPHC Strasbourg is envisaged. For this purpose a pixelated germanium detector has been scanned.

Ultra-low energy photoreceivers for optical interconnects

NASA Astrophysics Data System (ADS)

Going, Ryan Wayne

Optical interconnects are increasingly important for our communication and data center systems, and are forecasted to be an essential component of future computers. In order to meet these future demands, optical interconnects must be improved to consume less power than they do today. To do this, both more efficient transmitters and more sensitive receivers must be developed. This work addresses the latter, focusing on device level improvements to tightly couple a low capacitance photodiode with the first stage transistor of the receiver as a single phototransistor device. First I motivate the need for a coupled phototransistor using a simple circuit model which shows how receiver sensitivity is determined by photodiode capacitance and the length of wire connecting it to the first transistor in a receiver amplifier. Then I describe our use of the unique rapid melt growth technique, which is used to integrate crystalline germanium on silicon photonics substrates without an epitaxial reactor. The resulting material quality is demonstrated with high quality (0.95 A/W, 40+ GHz) germanium photodiodes on silicon waveguides. Next I describe two germanium phototransistors I have developed. One is a germanium- gated MOSFET on silicon photonics which has up to 18 A/W gate-controlled responsivity at 1550 nm. Simulations show how MOSFET scaling rules can be easily applied to increase both speed and sensitivity. The second is a floating base germanium bipolar phototransistor on silicon photonics with a 15 GHz gain x bandwidth product. The photoBJT also has a clear scaling path, and it is proposed to create a separate gain and absorption region photoBJT to realize the maximum benefit of scaling the BJT without negatively affecting its absorption and photocarrier collection. Following this design a 120 GHz gain x bandwidth photoBJT is simulated. Finally I present a metal-cavity, which can have over 50% quantum efficiency absorption in sub-100 aF germanium photodiodes, which addresses the issue of absorption in photodiodes which have been scaled to near sub-wavelength dimensions.

Coastline change and marine geo-hazards in the Yellow River Delta (China)

NASA Astrophysics Data System (ADS)

Zhou, L.; Liu, J.; Liu, X.

2003-04-01

COASTLINE CHANGE AND MARINE GEO-HAZARDS IN THE YELLOW RIVER DELTA (CHINA) Zhou Liangyong(1,2), Liu Jian(1,3), Liu Xiqing(1) (1)Qingdao Institute of Marine Geology,(2)Ocean University of China,(3)Research Centre for Coastal Geology, CGS qdzliangyong@cgs.gov.cn/Fax: +86-532-5720553 Satellite remote sensing, bathymetry and high-resolution seismic data have been used to examine the coastline change during the period from 1976 to 2001 and the offshore marine geo-hazards in the modern Yellow River Delta. Trends in the temporal sequence of the eight coastlines derived from Landsat images were used in the definition of erosional classes of the coastline. Four classes were distinguished, including rapid erosion (>100 m/yr), moderate erosion (20-100 m/yr), no detectable erosion (-1 - 20 m/yr), and accretion (-200--1 m/yr). We revealed the subtle variations in sea floor morphology and sediment geometries using high-resolution acoustic survey. Many kinds of geo-hazards were identified in the active subaqueous delta lobe and abandoned delta lobes, such as seabed erosions, gas-charged sediments, listric faults, synsedimentary rises, incised palaeo-valleys, infilled gullies, diapirs, active slope failures and sediment collapses. The resultant map of geo-envrionment and geo-hazards presents the coastline change and distribution of geo-hazards mentioned above in the Yellow River Delta. The gas-charged sediment distributes mainly in the abandoned delta lobes. The synsedimentary rise outside of the modern river mouth is a new evidence for the seabed mass-movement which modifies the progradational subaquaeous slopes of modern Yellow River Delta.

Photometrical research geostationary satellite "SBIRS GEO-2"

NASA Astrophysics Data System (ADS)

Sukhov, P. P.; Epishev, V. P; Sukhov, K. P; Kudak, V. I.

The multicolor photometrical observations GSS "Sbirs Geo-2" were carried in B,V,R filters out during the autumn equinox 2014 and spring 2015 y. Periodic appearance of many light curves and dips of mirror reflections suggests that the GSS was not in orbit in a static position, predetermined three-axis orientation and in dynamic motion. On the basis of computer modeling suggests the following dynamics GSS "Sbirs Geo-2" in orbit. Helically scanning the visible Earth's surface infrared satellite sensors come with period P1 = 15.66 sec. and the rocking of the GSS about the direction of the motion vector of the satellite in orbit with P2 = 62.64 sec., most likely with the purpose to survey the greatest possible portion of the earth's surface.

The analysis of behavior in orbit GSS two series of US early-warning system

NASA Astrophysics Data System (ADS)

Sukhov, P. P.; Epishev, V. P.; Sukhov, K. P.; Motrunych, I. I.

2016-09-01

Satellites Early Warning System Series class SBIRS US Air Force must replace on GEO early series DSP Series. During 2014-2016 the authors received more than 30 light curves "DSP-18 and "Sbirs-Geo 2". The analysis of the behavior of these satellites in orbit by a coordinate and photometric data. It is shown that for the monitoring of the Earth's surface is enough to place GEO 4 unit SBIRS across 90 deg.

Bridgman Growth of Germanium

NASA Technical Reports Server (NTRS)

Szofran, F. R.; Volz, M. P.; Cobb, S. D.; Motakef, S.

1997-01-01

The high-magnetic-field crystal growth facility at the Marshall Space Flight Center will be briefly described. This facility has been used to grow bulk germanium by the Bridgman technique in magnetic fields up to 5 Tesla. The results of investigations of ampoule material on the interface shape and thermal field applied to the melt on stability against convection will be discussed.

Alloys of clathrate allotropes for rechargeable batteries

DOEpatents

Chan, Candace K; Miller, Michael A; Chan, Kwai S

2014-12-09

The present disclosure is directed at an electrode for a battery wherein the electrode comprises clathrate alloys of silicon, germanium or tin. In method form, the present disclosure is directed at methods of forming clathrate alloys of silicon, germanium or tin which methods lead to the formation of empty cage structures suitable for use as electrodes in rechargeable type batteries.

Schottky barrier solar cell

NASA Technical Reports Server (NTRS)

Stirn, R. J.; Yeh, Y. C. M. (Inventor)

1981-01-01

A method of fabricating a Schottky barrier solar cell is described. The cell consists of a thin substrate of low cost material with at least the top surface of the substrate being electrically conductive. A thin layer of heavily doped n-type polycrystalling germanium is deposited on the substrate after a passivation layer is deposited to prevent migration of impurities into the polycrystalline germanium. The polycrystalline germanium is recrystallized to increase the crystal sizes to serve as a base layer on which a thin layer of gallium arsenide is vapor-epitaxilly grown followed by a thermally-grown oxide layer. A metal layer is deposited on the oxide layer and a grid electrode is deposited to be in electrical contact with the top surface of the metal layer.

OPTOELECTRONIC PROPERTIES AND THE GAP STATE DISTRIBUTION IN a-Si, Ge ALLOYS

NASA Astrophysics Data System (ADS)

Aljishi, S.; Smith, Z. E.; Wagner, S.

In this article we review optical and electronic transport data measured in amorphous silicon-germanium alloys with the goal of identifying the density of states as a function of alloy composition. The results show that while alloying a-Si:H with germanium has little effect on the valence band tail, the conduction band tail density of states is increased dramatically. Defect distributions both above and below midgap are detected and identified with the dangling bond D+/° and D°/- states. The density of deep defects below midgap increases exponentially with germanium content. Above midgap, a large concentration of defects lying between 0.3 and 0.5 eV below the conduction band edge has a strong effect on transient electron transport.

Semiconductor with protective surface coating and method of manufacture thereof. [Patent application

DOEpatents

Hansen, W.L.; Haller, E.E.

1980-09-19

Passivation of predominantly crystalline semiconductor devices is provided for by a surface coating of sputtered hydrogenated amorphous semiconductor material. Passivation of a radiation detector germanium diode, for example, is realized by sputtering a coating of amorphous germanium onto the etched and quenched diode surface in a low pressure atmosphere of hydrogen and argon. Unlike prior germanium diode semiconductor devices, which must be maintained in vacuum at cryogenic temperatures to avoid deterioration, a diode processed in the described manner may be stored in air at room temperature or otherwise exposed to a variety of environmental conditions. The coating compensates for pre-existing undesirable surface states as well as protecting the semiconductor device against future impregnation with impurities.

Time-resolved measurements of the angular distribution of lasing at 23.6 nm in Ne-like germanium

NASA Astrophysics Data System (ADS)

Kodama, R.; Neely, D.; Dwivedi, L.; Key, M. H.; Krishnan, J.; Lewis, C. L. S.; O'Neill, D.; Norreys, P.; Pert, G. J.; Ramsden, S. A.; Tallents, G. J.; Uhomoibhi, J.; Zhang, J.

1992-06-01

The time dependence of the angular distribution of soft X-ray lasing at 23.6 nm in Ne-like germanium has been measured using a streak camera. Slabs of germanium have been irradiated over ≈ 22 mm length × 100 μm width with three line focussed beams of the SERC Rutherford Appleton Laboratory VULCAN laser at 1.06 μm wavelength. The laser beam sweeps in time towards the target surface plane and the divergence broadens with time. The change of the peak intensity pointing and the broadening of the profile with time are consistent with expectations of the time dependence of refraction and divergence due to density gradients in the plasma.

On the introduction of a measurement standard for high-purity germanium crystals to be used in radiation detectors

NASA Astrophysics Data System (ADS)

Darken, L.

1994-02-01

The IEEE and ANSI have recently approved "Standard Test Procedures for High-Purity Germanium Crystals for Radiation Detectors" proposed by the IEEE/NPSS/Nuclear Instruments and Detectors Committee. The standard addresses three aspects of the characterisation of high-purity germanium: (i) the determination by the van der Pauw method of the net carrier concentration and type; (ii) the measurement by capacitance transient techniques of the concentration of trapping levels; (iii) the description of the crystallographic properties revealed by preferential etching. In addition to describing the contents of this standard, the purpose of this work is also to place the issues faced in the context of professional consensus: points of agreement, points of disagreement, and subjects poorly understood.

High performance geospatial and climate data visualization using GeoJS

NASA Astrophysics Data System (ADS)

Chaudhary, A.; Beezley, J. D.

2015-12-01

GeoJS (https://github.com/OpenGeoscience/geojs) is an open-source library developed to support interactive scientific and geospatial visualization of climate and earth science datasets in a web environment. GeoJS has a convenient application programming interface (API) that enables users to harness the fast performance of WebGL and Canvas 2D APIs with sophisticated Scalable Vector Graphics (SVG) features in a consistent and convenient manner. We started the project in response to the need for an open-source JavaScript library that can combine traditional geographic information systems (GIS) and scientific visualization on the web. Many libraries, some of which are open source, support mapping or other GIS capabilities, but lack the features required to visualize scientific and other geospatial datasets. For instance, such libraries are not be capable of rendering climate plots from NetCDF files, and some libraries are limited in regards to geoinformatics (infovis in a geospatial environment). While libraries such as d3.js are extremely powerful for these kinds of plots, in order to integrate them into other GIS libraries, the construction of geoinformatics visualizations must be completed manually and separately, or the code must somehow be mixed in an unintuitive way.We developed GeoJS with the following motivations:• To create an open-source geovisualization and GIS library that combines scientific visualization with GIS and informatics• To develop an extensible library that can combine data from multiple sources and render them using multiple backends• To build a library that works well with existing scientific visualizations tools such as VTKWe have successfully deployed GeoJS-based applications for multiple domains across various projects. The ClimatePipes project funded by the Department of Energy, for example, used GeoJS to visualize NetCDF datasets from climate data archives. Other projects built visualizations using GeoJS for interactively exploring data and analysis regarding 1) the human trafficking domain, 2) New York City taxi drop-offs and pick-ups, and 3) the Ebola outbreak. GeoJS supports advanced visualization features such as picking and selecting, as well as clustering. It also supports 2D contour plots, vector plots, heat maps, and geospatial graphs.

Representations of the Stratospheric Polar Vortices in Versions 1 and 2 of the Goddard Earth Observing System Chemistry-Climate Model (GEOS CCM)

NASA Technical Reports Server (NTRS)

Pawson, S.; Stolarski, R.S.; Nielsen, J.E.; Perlwitz, J.; Oman, L.; Waugh, D.

2009-01-01

This study will document the behavior of the polar vortices in two versions of the GEOS CCM. Both versions of the model include the same stratospheric chemistry, They differ in the underlying circulation model. Version 1 of the GEOS CCM is based on the Goddard Earth Observing System, Version 4, general circulation model which includes the finite-volume (Lin-Rood) dynamical core and physical parameterizations from Community Climate Model, Version 3. GEOS CCM Version 2 is based on the GEOS-5 GCM that includes a different tropospheric physics package. Baseline simulations of both models, performed at two-degree spatial resolution, show some improvements in Version 2, but also some degradation, In the Antarctic, both models show an over-persistent stratospheric polar vortex with late breakdown, but the year-to-year variations that are overestimated in Version I are more realistic in Version 2. The implications of this for the interactions with tropospheric climate, the Southern Annular Mode, will be discussed. In the Arctic both model versions show a dominant dynamically forced variabi;ity, but Version 2 has a persistent warm bias in the low stratosphere and there are seasonal differences in the simulations. These differences will be quantified in terms of climate change and ozone loss. Impacts of model resolution, using simulations at one-degree and half-degree, and changes in physical parameterizations (especially the gravity wave drag) will be discussed.

Femtosecond tracking of carrier relaxation in germanium with extreme ultraviolet transient reflectivity

NASA Astrophysics Data System (ADS)

Kaplan, Christopher J.; Kraus, Peter M.; Ross, Andrew D.; Zürch, Michael; Cushing, Scott K.; Jager, Marieke F.; Chang, Hung-Tzu; Gullikson, Eric M.; Neumark, Daniel M.; Leone, Stephen R.

2018-05-01

Extreme ultraviolet (XUV) transient reflectivity around the germanium M4 ,5 edge (3 d core-level to valence transition) at 30 eV is advanced to obtain the transient dielectric function of crystalline germanium [100] on femtosecond to picosecond time scales following photoexcitation by broadband visible-to-infrared (VIS/NIR) pulses. By fitting the transient dielectric function, carrier-phonon induced relaxations are extracted for the excited carrier distribution. The measurements reveal a hot electron relaxation rate of 3.2 ±0.2 ps attributed to the X -L intervalley scattering and a hot hole relaxation rate of 600 ±300 fs ascribed to intravalley scattering within the heavy hole (HH) band, both in good agreement with previous work. An overall energy shift of the XUV dielectric function is assigned to a thermally induced band gap shrinkage by formation of acoustic phonons, which is observed to be on a timescale of 4-5 ps, in agreement with previously measured optical phonon lifetimes. The results reveal that the transient reflectivity signal at an angle of 66∘ with respect to the surface normal is dominated by changes to the real part of the dielectric function, due to the near critical angle of incidence of the experiment (66∘-70∘) for the range of XUV energies used. This work provides a methodology for interpreting XUV transient reflectivity near core-level transitions, and it demonstrates the power of the XUV spectral region for measuring ultrafast excitation dynamics in solids.

Optimization of chemical and instrumental parameters in hydride generation laser-induced breakdown spectrometry for the determination of arsenic, antimony, lead and germanium in aqueous samples.

PubMed

Yeşiller, Semira Unal; Yalçın, Serife

2013-04-03

A laser induced breakdown spectrometry hyphenated with on-line continuous flow hydride generation sample introduction system, HG-LIBS, has been used for the determination of arsenic, antimony, lead and germanium in aqueous environments. Optimum chemical and instrumental parameters governing chemical hydride generation, laser plasma formation and detection were investigated for each element under argon and nitrogen atmosphere. Arsenic, antimony and germanium have presented strong enhancement in signal strength under argon atmosphere while lead has shown no sensitivity to ambient gas type. Detection limits of 1.1 mg L(-1), 1.0 mg L(-1), 1.3 mg L(-1) and 0.2 mg L(-1) were obtained for As, Sb, Pb and Ge, respectively. Up to 77 times enhancement in detection limit of Pb were obtained, compared to the result obtained from the direct analysis of liquids by LIBS. Applicability of the technique to real water samples was tested through spiking experiments and recoveries higher than 80% were obtained. Results demonstrate that, HG-LIBS approach is suitable for quantitative analysis of toxic elements and sufficiently fast for real time continuous monitoring in aqueous environments. Copyright © 2013 Elsevier B.V. All rights reserved.

Performance of the THS4302 and the Class V Radiation-Tolerant THS4304-SP Silicon Germanium Wideband Amplifiers at Extreme Temperatures

NASA Technical Reports Server (NTRS)

Patterson, Richard L.; Elbuluk, Malik; Hammoud, Ahmad; VanKeuls, Frederick W.

2009-01-01

This report discusses the performance of silicon germanium, wideband gain amplifiers under extreme temperatures. The investigated devices include Texas Instruments THS4304-SP and THS4302 amplifiers. Both chips are manufactured using the BiCom3 process based on silicon germanium technology along with silicon-on-insulator (SOI) buried oxide layers. The THS4304-SP device was chosen because it is a Class V radiation-tolerant (150 kRad, TID silicon), voltage-feedback operational amplifier designed for use in high-speed analog signal applications and is very desirable for NASA missions. It operates with a single 5 V power supply [1]. It comes in a 10-pin ceramic flatpack package, and it provides balanced inputs, low offset voltage and offset current, and high common mode rejection ratio. The fixed-gain THS4302 chip, which comes in a 16-pin leadless package, offers high bandwidth, high slew rate, low noise, and low distortion [2]. Such features have made the amplifier useful in a number of applications such as wideband signal processing, wireless transceivers, intermediate frequency (IF) amplifier, analog-to-digital converter (ADC) preamplifier, digital-to-analog converter (DAC) output buffer, measurement instrumentation, and medical and industrial imaging.

Analysis of Faint Glints from Stabilized GEO Satellites

NASA Astrophysics Data System (ADS)

Hall, D.; Kervin, P.

2013-09-01

Ground-based telescopes routinely acquire temporal brightness measurements of satellites in geo-stationary and geo-synchronous orbit that provide valuable characterization information. For instance, GEO satellites that are not stabilized tend to rotate, and produce brightnesses that vary in time with frequencies corresponding to rotation rates. Temporal brightness patterns can also be exploited to characterize stabilized GEO satellites. For example, many operational GEO satellites have solar panels that glint when they reflect sunlight towards an observer in a mirror-like fashion. These well-known solar panel glints can be remarkably bright, often exceeding several stellar magnitudes in amplitude. Measured brightnesses and times of these glints can be exploited to estimate the size, segmentation, and alignment of the solar array, valuable information about the satellite's power generation and consumption capabilities. However, satellites can produce other glints in addition to those originating from solar panels. These glints can be much fainter, with amplitudes as small as 0.2 magnitudes. Several observations of GEO satellites show several such glints occurring during the span of a single night. Furthermore, many of these recur from night to night when observed from a single ground-based site, but with subtle, incremental changes in both peak times and brightnesses. These fainter glints must originate from reflective elements mounted on the satellite's main bus, solar panel structure, or other peripheral structures that might be stationary or moving with respect to the main bus. Our analysis indicates that such glints can be exploited for GEO satellite characterization.

Magnetocrystalline anisotropy of Fe2 + ion in silicon- or germanium-substituted yttrium iron garnet at zero temperature

NASA Astrophysics Data System (ADS)

Rudowicz, Czeslaw

1982-01-01

The present work reports the theoretical considerations of the magnetocrystalline anisotropy of ferrous ions induced by tetravalent dopants in yttrium iron garnet. Using the spin Hamiltonian developed earlier by us and the molecular field (h) approximation we derive the cubic anisotropy constants K1 and K2 at zero temperature. We adopt the Alben's et al. model of twelve inequivalent Fe2+ sites in silicon-substituted yttrium iron garnet. Results are given for h = 400, 300, 200 and the spin Hamiltonian parameters with the trigonal Δ = 300, 400, 500, 600, 700 and the nontrigonal crystal field parameter Γ = 200, 300 cm-1. The agreement with the experimental K1 and K2 is quite good. The discussion reveals that the properties of the far and near sites in the two-center model can now be theoretically explained. The theoretical ratios of K1(far) to K1(near) agree well with experiment. Thus our results speak in favor of the orbital singlet rather than the doublet model assumed previously for Fe2+ in silicon- or germanium-substituted yttrium iron garnets.

Structural, mechanical and optical investigations in the TeO2-rich part of the TeO2-GeO2-ZnO ternary glass system

NASA Astrophysics Data System (ADS)

Ghribi, N.; Dutreilh-Colas, M.; Duclère, J.-R.; Gouraud, F.; Chotard, T.; Karray, R.; Kabadou, A.; Thomas, P.

2015-02-01

Stable glasses are successfully synthesized in the TeO2-GeO2-ZnO system at 850 °C by the melt-quenching method and the glass forming domain is determined in the TeO2-rich part of the diagram. The thermal study, carried out using differential scanning calorimetry, reveals that the glass transition temperature, as well as the thermal stability, increases with the addition of ZnO or GeO2. Bulk glass samples are elaborated within two series of compositions, corresponding to fixed concentrations in GeO2 (respectively 5 or 10 mol. %), and to various contents in ZnO. Structural changes caused by the ZnO addition are discussed based on Raman spectroscopy data. A progressive but very moderate network depolymerization is shown with increasing amount of ZnO. However, two different regimes can be identified, depending on the ZnO content. It is believed that ZnO acts as a network modifier for compositions below 20 mol. %, and starts to participate as a glass network former over such concentration. It is well evidenced that GeO2 contributes to the increase in Young's modulus E, evaluated from ultrasonic echography measurements. In addition, this oxide favors the network reticulation detected by the decrease of the Poisson ratio and the increase of the fractal bond connectivity. However, the role of ZnO is more complicated and will be extensively discussed. The decrease in the atomic packing density Cg probably explains the global evolution of E as a function of ZnO content. The refractive indices and optical band gap energies are extracted from UV-Visible-NIR optical transmission data. For the studied glasses, it is found that the transmission threshold decreases with larger ZnO contents, reflecting the increase in the optical band gap value. Refractive index is finally seen to decrease as a function of both ZnO and GeO2 contents. Such variation is explained by the decrease of the molar electronic polarizability, and by the lower optical basicity values known for TeO3 entities in comparison to TeO4 units.